tag:theconversation.com,2011:/ca-fr/topics/blood-2517/articles
Blood – La Conversation
2024-03-07T18:23:33Z
tag:theconversation.com,2011:article/225094
2024-03-07T18:23:33Z
2024-03-07T18:23:33Z
We’re working out how to solve crimes in space – the final frontier of forensic science
<p>Nasa’s Artemis program is scheduled to <a href="https://www.nasa.gov/specials/artemis/">return astronauts to the Moon</a> and establish a permanent orbiting laboratory by the end of the decade. </p>
<p>Meanwhile, private companies are making significant steps in taking paying customers further into space. As humanity’s footprint expands beyond the familiar terrains of Earth to the Moon and possibly beyond, an intriguing new field emerges from the final frontier: astroforensics. </p>
<p>This discipline, still in its infancy, is propelled by the inevitability of human nature. Space presents a unique and harsh environment for forensic investigations. Settings that present altered gravity, cosmic radiation, extremes in temperature, and the need for oxygen-providing climate systems provide a few examples of the unearthly variables that are faced by future explorers. </p>
<p>Unlike Earth, where gravity, a constant force, shapes many aspects of our reality, the <a href="https://www.nasa.gov/centers-and-facilities/glenn/what-is-microgravity/">significant reduction of gravity in space</a> introduces novel challenges in understanding how evidence behaves. This shift is crucial for forensic sciences like bloodstain pattern analysis, which relies heavily on gravitational effects to determine the circumstances under which blood stains are formed.</p>
<p>The thought of gravity in space immediately conjures images of astronauts hauntingly suspended in the void of space or floating gymnastics in the <a href="https://www.nasa.gov/international-space-station/">International Space Station (ISS)</a>. </p>
<p>However, true zero gravity exists far away from any celestial bodies. When close to a body such as a Moon or a planet, there will be a gravitational influence, including when in orbit around a planet like Earth. </p>
<p>Therefore, most environments in space have low or microgravity rather than zero gravity. Given that gravity is ubiquitous and largely constant, we pay very little attention to it, usually automatically factoring it in to calculations as a constant without a second thought. </p>
<h2>Altered gravity</h2>
<p>But for a forensic science discipline like bloodstain pattern analysis, gravity
plays a critical role in how airborne liquid blood interacts with a surface and creates stain patterns. <a href="https://en.wikipedia.org/wiki/Bloodstain_pattern_analysis">Bloodstain pattern analysis</a> is the use of fluid dynamics, physics, and mathematics to understand the flight and origin of blood and interpret how it was deposited on a surface in criminal investigations.</p>
<p><a href="https://www.sciencedirect.com/science/article/pii/S2665910724000070">In a recently published study</a>, we and our colleagues sought to understand the beginning principles of how the altered gravity environment of space will affect future forensic science disciplines. </p>
<p>For this study, published in Forensic Science International: Reports, we used a <a href="https://www.nasa.gov/mission/parabolic-flight/">parabolic flight research plane</a> that induces short periods of microgravity because of its up-and-down flight path. This type of flight has colloquially been referred to as the “vomit comet”. </p>
<p>During this period of freefalling microgravity, a number of blood drops would be projected onto a piece of paper, and the resulting bloodstain was then analysed using routine earthbound protocols. While the concept sounds simple, there was a challenge in creating a safe and controllable area to conduct experiments in a plane that was basically falling to Earth for 20 seconds. </p>
<p>Therefore, the experimental environment had to be attached to the cabin of the
research plane, and all bloodstain generation and documentation made easily controllable. Experiments were conducted inside a repurposed paediatric incubation chamber, referred to as a glove box. This chamber is used in space medicine research for studying haemorrhage control. </p>
<p>A synthetic analogue of blood was used instead of real blood due to biohazard concerns in the cabin of the plane. This analogue substitute mimicked the physical properties of blood’s viscosity and surface tension. To initiate the experiment, the analogue blood was loaded into a syringe, and once microgravity was induced in free-fall, the syringe was manually depressed to project the blood across 20cm onto a sheet of white paper. </p>
<p>While this bears little resemblance to true criminal scenarios, it is the interaction between the blood and the surface that is of interest to the forensic investigator –- rather than the actual mechanism of projection. The blood-stained papers were then photographed and analysed as per normal procedures.</p>
<p>We found that microgravity does indeed change the behaviour of the blood
drops and the stains they create. On Earth, blood tends to fall in a parabolic manner, with gravity pulling down on it until it strikes a surface. But in this case, the blood continued to travel in a straight line until it hit the surface.</p>
<p>This straight-line flight path is a fluid example of inertia in action. However, with a distance of only 20cm, this had minimal effect on the subsequent pattern. </p>
<p>This difference would become more apparent over larger distances, but the operational limitation of the parabolic research aircraft means it would be difficult to recreate effectively. The second key observation was the spreading action of the blood upon striking the surface. </p>
<p>In the typical gravity environment of Earth, liquid blood drops will undergo a series of stages in the stain creation process. This entails the droplet’s collapse, the formation of a small wave, and the spread into a final stain shape. </p>
<p>However, when gravity is eliminated from this action, the spreading action is inhibited by the dominating force of surface tension and cohesion, resulting in a stain shape and size that is smaller than its terrestrial twin.</p>
<p>We are at the beginning of a new research era, exploring the impact of the extra-
terrestrial environment upon the behaviour of forensic evidence. Still, the impact of this research is not only limited to forensic sciences but more traditional natural sciences as well, such as <a href="https://ntrs.nasa.gov/citations/19890015838">fluid dynamics in spacecraft design</a> and analysing faults in space forensic engineering following a spacecraft malfunction. </p>
<p>In order to expand research in this new forensic discipline, larger microgravity environments will be required and the authors would be more than happy to operate the galaxy’s first extraterrestrial forensic science laboratory.</p><img src="https://counter.theconversation.com/content/225094/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Zack Kowalske received funding from the International Association of Bloodstain Pattern Analysts' Dan Rahn Research Grant. </span></em></p><p class="fine-print"><em><span>Graham Williams does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
If we need to use forensic techniques in space, we’ll need to understand how things behave differently in microgravity.
Graham Williams, Professor of Forensic Science, University of Hull
Zack Kowalske, PhD Researcher, Staffordshire University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/223246
2024-02-19T12:48:31Z
2024-02-19T12:48:31Z
What bodily secretions like blood, wax and tears can tell us about our health
<figure><img src="https://images.theconversation.com/files/575648/original/file-20240214-22-kbj0it.jpg?ixlib=rb-1.1.0&rect=5%2C7%2C1242%2C823&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/caitlinator/">Caitlin Regan/flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Dry scalp? Blocked ears? Crusted eyes? Our bodies produce many different unusual, sometimes repellent secretions, and their function doesn’t always seem entirely clear. But each has their own important role, which often goes unappreciated. </p>
<p><a href="https://pubmed.ncbi.nlm.nih.gov/27148560/">Flaky or dry scalp is an extremely common condition</a>, but in severe cases it certainly doesn’t feel trivial. Put aside notions that it’s a factor of poor hygiene – the underlying cause is not completely clear, but it may be exacerbated by hair care regimes which dry or irritate the scalp. What is known is that flakes of dandruff are comprised of cell complexes, arising from sloughed off skin. </p>
<p>The outermost layer of the skin (the epidermis) is comprised in part of dead cells, that act as an <a href="https://pubmed.ncbi.nlm.nih.gov/22515370/">essential protective barrier</a>. Dead cells shed more easily, and will be replaced with new ones as skin constantly regenerates and grows. If this happens at too great a rate, the result is dandruff.</p>
<p>The first measure is to try an over the counter anti-dandruff shampoo. These contain antifungal and anti-inflammatory compounds both understood to have dandruff healing properties since fungi and inflammation are believed to be potential factors in the development of a crusty scalp. These compounds – selenium and coal tar for instance – can also help relieve the symptoms of itch which may often prove worse than the flaking. </p>
<p>It’s worthwhile trialling a different formula if the first doesn’t work. Certain conditions like <a href="https://jddonline.com/articles/treatment-of-scalp-psoriasis-S1545961622P0833X/">psoriasis</a> and eczema can also be the underlying cause, and may require alternative treatment. </p>
<h2>Scabs may be unsightly – but they function beautifully</h2>
<p>Scabs are the body’s natural response to being wounded. Cuts, punctures or breaks in the skin open up blood vessels to the atmosphere around us. In response, the bloodstream recruits its clotting agents – the platelets – to help plug the gap. Platelets bring blood cells together to form a clot, creating a bung to stop bleeding, and prevent bacteria shifting from the skin into the circulation, where they can do more damage. When the clot dries out, a scab is formed. </p>
<p>Scabs can look horrible, but don’t worry – they’re meant to. Sometimes pus forms which can give scabs a yellow rather than reddish-brown colour, and might suggest that an infection is brewing. <a href="https://www.nhs.uk/conditions/cuts-and-grazes/">Redness of the uninjured skin</a> around and tracking away from the scab is another telltale sign of possible infection too. </p>
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<p>Resist the temptation to pick off a scab from the skin, no matter how tempting it may seem. They may be unsightly, or itchy, but they’re performing the job they’re supposed to – keeping out bugs and allowing wounds to heal. Take good care of them instead, by keeping them untouched and clean, and wait for them to shed themselves. </p>
<h2>The eyes have it</h2>
<p>Sleep sand. Eye bogies. Doze dust. The debris we find in the corners of our eyes each morning goes by many different names. Few of us know exactly what it is, why it’s there, or its scientific name, rheum. </p>
<p>Tears lubricate the exposed surface of the eyes, stopping them from getting dry and sore. They also hose away grit and dust and have <a href="https://www.sciencedirect.com/science/article/pii/S0014483513002121?via%3Dihub">natural antibacterial properties</a> to fight infections. </p>
<p>But our eyes make more than just tears. The lids have many little glands which discharge <a href="https://pubmed.ncbi.nlm.nih.gov/28669846/">natural oily substances</a> allowing tears to spread evenly across the eye and prevent them evaporating away. In addition, <a href="https://pubmed.ncbi.nlm.nih.gov/32667250/">mucus-secreting glands</a>, much like those in the nose that make snot, make a thin mucus which also helps to trap and eliminate rogue particles. </p>
<p>In large amounts, oil and mucus can irritate the eyes, but normally get swept away by tears and blinking during the day. By night, our eyes remain shut and rheum builds up. Whether they take on the appearance of sticky bogies or crusts depends on how dry they get overnight, and may be proportional to how long you sleep.</p>
<h2>(Ear) waxing lyrical</h2>
<p>Ear wax is a largely invisible entity – more often felt than seen. Notice a feeling of blocked or congested ears, or a smothered sense of hearing, and the wax in your ears might be becoming problematic. </p>
<p>It also has a clinical name – cerumen. In part, <a href="https://academic.oup.com/qjmed/article/97/8/477/1588624?login=true">it’s made of oils and sweat</a> from glands lining the ear canal. The majority of ear wax though is keratin, the natural protein that toughens skin, hair and nails. This is because the <a href="https://pubmed.ncbi.nlm.nih.gov/37517877/">ear canal is lined with skin</a>, all the way up to the ear drum. In mixing with the secretions, shed skin produces a waxy substance ranging in colours across the brown spectrum. </p>
<p>Fresh, healthy earwax tends to be yellow to honey-brown in colour, whereas older, thicker earwax becomes darker brown, sometimes even black. Notice red or green staining, then blood or bacteria may be mixing with the wax. Among other diagnoses, this raises the possibility of an ear infection, especially if there’s also a runny or foul-smelling discharge. </p>
<p>Like many of the other bodily secretions, cerumen also traps debris and other nasties (<a href="https://www.medicalnewstoday.com/articles/322064">even insects</a>) that could irritate or damage the delicate ear drum. But problems arise if the wax builds up or hardens too much, blocking conduction of sound to the drum, and dampening your hearing.</p>
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<p>Nothing smaller than an index finger (with well-trimmed nails) should ever go in your ear canal. Stop cleaning with cotton buds too. All this does is compress cerumen into little impacted cakes. Instead, medicinal olive oil from the pharmacy can help soften it down, <a href="https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD012171.pub2/full">making it easier for the ear to clear it naturally</a>. </p>
<p>Blood, sweat and tears – and wax, skin and mucus – can cause many commonplace issues. But look beyond these minor ailments and be grateful that they’re there. You’d be sorry if they weren’t.</p><img src="https://counter.theconversation.com/content/223246/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dan Baumgardt does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Scabs, ear wax and eye crusts might sound, and even look, gross but they do essential work keeping our bodies clear of infection
Dan Baumgardt, Senior Lecturer, School of Physiology, Pharmacology and Neuroscience, University of Bristol
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/216341
2024-02-05T13:30:15Z
2024-02-05T13:30:15Z
What do your blood test results mean? A toxicologist explains the basics of how to interpret them
<figure><img src="https://images.theconversation.com/files/570974/original/file-20240123-19-h34bd4.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2120%2C1414&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">From CBC to CMP and beyond, blood test panels provide essential information to health practitioners.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/workplace-of-laboratory-with-blood-tubes-samples-royalty-free-image/1389684965">angelp/iStock via Getty Images Plus</a></span></figcaption></figure><p>Your blood <a href="https://www.ncbi.nlm.nih.gov/books/NBK279392/">serves numerous roles</a> to maintain your health. To carry out these functions, blood contains a multitude of components, including red blood cells that transport oxygen, nutrients and hormones; white blood cells that remove waste products and support the immune system; plasma that regulates temperature; and platelets that help with clotting.</p>
<p>Within the blood are also numerous molecules formed as byproducts of normal biochemical functions. When these molecules indicate how your cells are responding to disease, injury or stress, scientists often refer to them as <a href="https://doi.org/10.1097/COH.0b013e32833ed177">biological markers, or biomarkers</a>. Thus, biomarkers in a blood sample can represent a snapshot of the current biochemical state of your body, and analyzing them can provide information about various aspects of your health.</p>
<p><a href="https://www.researchgate.net/profile/Brad-Reisfeld">As a toxicologist</a>, I study the effects of drugs and environmental contaminants on human health. As part of my work, I rely on various health-related biomarkers, many of which are measured using conventional blood tests.</p>
<p>Understanding what <a href="https://www.nhlbi.nih.gov/health/blood-tests">common blood tests</a> are intended to measure can help you better interpret the results. If you have results from a recent blood test handy, please follow along.</p>
<figure>
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<figcaption><span class="caption">Blood samples go through several processing steps after they’re drawn.</span></figcaption>
</figure>
<h2>Normal blood test ranges</h2>
<p><a href="https://theconversation.com/how-do-blood-tests-work-medical-laboratory-scientists-explain-the-pathway-from-blood-draw-to-diagnosis-and-treatment-196874">Depending on the lab</a> that analyzed your sample, the results from your blood test may be broken down into individual tests or collections of <a href="https://www.testing.com/tests/chemistry-panels/">related tests called panels</a>. Results from these panels can allow a health care professional to recommend preventive care, detect potential diseases and monitor ongoing health conditions.</p>
<p>For each of the tests listed in your report, there will typically be a number corresponding to your test result and a <a href="https://www.testing.com/articles/laboratory-test-reference-ranges/">reference range or interval</a>. This range is essentially the upper and lower limits within which most healthy people’s test results are expected to fall.</p>
<p>Sometimes called a normal range, a reference interval is based on <a href="https://webstore.ansi.org/preview-pages/CLSI/preview_CLSI+C28-A3.pdf">statistical analyses</a> of tests from a large number of patients in a <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4975205/">reference population</a>. Normal levels of some biomarkers are expected to vary across a group of people, depending on their age, sex, ethnicity and other attributes. </p>
<p>So, separate reference populations are often created from people with a particular attribute. For example, a reference population could comprise all women or all children. A patient’s test value can then be appropriately compared with results from the reference population that fits them best.</p>
<p>Reference intervals <a href="https://doi.org/10.1001/archinternmed.2007.131">vary from lab to lab</a> because each may use different testing methods or reference populations. This means you might not be able to compare your results with reference intervals from other labs. To determine how your test results compare with the normal range, you need to check the reference interval listed on your lab report.</p>
<p>If you have results for a given test from different labs, your clinician will likely focus on test trends relative to their reference intervals and not the numerical results themselves.</p>
<h2>Interpreting your blood test results</h2>
<p>There are <a href="https://kidshealth.org/en/parents/blood-test-types.html">numerous blood panels</a> intended to test specific aspects of your health. These include panels that look at the cellular components of your blood, biomarkers of kidney and liver function, and many more.</p>
<p>Rather than describe each panel, let’s look at a hypothetical case study that requires using several panels to diagnose a disease.</p>
<p>In this situation, a patient visits their health care provider for fatigue that has lasted several months. <a href="https://www.merckmanuals.com/professional/special-subjects/nonspecific-symptoms/fatigue">Numerous factors and disorders</a> can result in prolonged or chronic fatigue.</p>
<p>Based on a physical examination, other symptoms and medical history, the health practitioner suspects that the patient could be suffering from any of the following: anemia, an underactive thyroid or diabetes.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/570977/original/file-20240123-21-rfgobx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Close-up of a person holding gauze against the crook of their arm while another person holds up two heparin tubes of blood" src="https://images.theconversation.com/files/570977/original/file-20240123-21-rfgobx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/570977/original/file-20240123-21-rfgobx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/570977/original/file-20240123-21-rfgobx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/570977/original/file-20240123-21-rfgobx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/570977/original/file-20240123-21-rfgobx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/570977/original/file-20240123-21-rfgobx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/570977/original/file-20240123-21-rfgobx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Blood tests provide clinicians with more information to guide diagnoses and treatment decisions.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/female-nurse-holding-blood-collection-tubes-royalty-free-image/1463489972">FluxFactory/E+ via Getty Images</a></span>
</figcaption>
</figure>
<p>Blood tests would help further narrow down the cause of fatigue.</p>
<p><a href="https://www.nhlbi.nih.gov/health/anemia">Anemia</a> is a condition involving reduced blood capacity to transport oxygen. This results from either lower than normal levels of red blood cells or a decrease in the quantity or quality of <a href="https://theconversation.com/why-do-we-bleed-a-hematologist-explains-how-the-body-prevents-blood-loss-after-injury-174581">hemoglobin</a>, the protein that allows these cells to transport oxygen. </p>
<p>A <a href="https://medlineplus.gov/lab-tests/complete-blood-count-cbc/">complete blood count panel</a> measures various components of the blood to provide a comprehensive overview of the cells that make it up. <a href="https://www.nhlbi.nih.gov/health/anemia/diagnosis">Low values</a> of red blood cell count, or RBC, hemoglobin, or Hb, and hematocrit, or HCT, would indicate that the patient is suffering from anemia.</p>
<p><a href="https://www.niddk.nih.gov/health-information/endocrine-diseases/hypothyroidism">Hypothyroidism</a> is a disorder in which the thyroid gland does not produce enough thyroid hormones. These include thyroid-stimulating hormone, or TSH, which stimulates the thyroid gland to release two other hormones: triiodothyronine, or T3, and thyroxine, or T4. The <a href="https://medlineplus.gov/thyroidtests.html">thyroid function panel</a> measures the levels of these hormones to assess thyroid-related health.</p>
<p><a href="https://www.cdc.gov/diabetes/basics/diabetes.html">Diabetes</a> is a disease that occurs when blood sugar levels are too high. Excessive glucose molecules in the bloodstream can bind to hemoglobin and form what’s called glycated hemoglobin, or HbA1c. A <a href="https://doi.org/10.4137/BMI.S38440">hemoglobin A1c test</a> measures the percentage of HbA1c present relative to the total amount of hemoglobin. This provides a history of glucose levels in the bloodstream over a period of about three months prior to the test.</p>
<p>Providing additional information is the <a href="https://medlineplus.gov/lab-tests/basic-metabolic-panel-bmp/">basic metabolic panel, or BMP</a>, which measures the amount various substances in your blood. These include:</p>
<ul>
<li>Glucose, a type of sugar that provides energy for your body and brain. Relevant to diabetes, the BMP measures the blood glucose levels at the time of the test.</li>
<li>Calcium, a mineral essential for proper functioning of your nerves, muscles and heart.</li>
<li>Creatinine, a byproduct of muscle activity.</li>
<li>Blood urea nitrogen, or BUN, the amount of the waste product urea your kidneys help remove from your blood. These indicate the status of a person’s metabolism, kidney health and electrolyte balance.</li>
</ul>
<p>With results from each of these panels, the health professional would assess the patient’s values relative to their reference intervals and determine which condition they most likely have.</p>
<p>Understanding the purpose of blood tests and how to interpret them can help patients partner with their health care providers and become more informed about their health.</p><img src="https://counter.theconversation.com/content/216341/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Brad Reisfeld does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Your blood contains a wealth of information about the state of your health. Analyzing the levels of each component is an important part of diagnosis.
Brad Reisfeld, Professor of Chemical and Biological Engineering, Biomedical Engineering, and Public Health, Colorado State University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/219169
2024-02-05T13:30:00Z
2024-02-05T13:30:00Z
Why do people and animals need to breathe? A biologist explains why you need a constant source of oxygen
<figure><img src="https://images.theconversation.com/files/567973/original/file-20240104-26-jrvms0.jpg?ixlib=rb-1.1.0&rect=419%2C364%2C3255%2C2085&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Your blood's natural limit to how much oxygen it can hold means you can't stockpile it.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/girl-swimming-in-idyllic-caribbean-sea-take-a-royalty-free-image/1394071551">Lisa520/E+ via Getty Images</a></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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</figcaption>
</figure>
<p><em><a href="https://theconversation.com/us/topics/curious-kids-us-74795">Curious Kids</a> is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">curiouskidsus@theconversation.com</a>.</em></p>
<hr>
<blockquote>
<p><strong>Why do humans and animals have to breathe? – Tennessee, age 7, Hartford, Kentucky</strong></p>
</blockquote>
<hr>
<p>You need to breathe for the same reason you need to eat: It helps you make the energy your body requires. </p>
<p>You probably already know that food is fuel for your body. When you eat, food gets broken down in your stomach and <a href="https://www.vattenhallen.lu.se/english/experiences/from-mouth-to-rectum/">enters your bloodstream</a>.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/568258/original/file-20240108-16-q7f3ve.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A plastic object on a stand that is tube shaped with part of it cut off showing an interior space with fuzzy looking walls with dividers." src="https://images.theconversation.com/files/568258/original/file-20240108-16-q7f3ve.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/568258/original/file-20240108-16-q7f3ve.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=801&fit=crop&dpr=1 600w, https://images.theconversation.com/files/568258/original/file-20240108-16-q7f3ve.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=801&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/568258/original/file-20240108-16-q7f3ve.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=801&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/568258/original/file-20240108-16-q7f3ve.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1006&fit=crop&dpr=1 754w, https://images.theconversation.com/files/568258/original/file-20240108-16-q7f3ve.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1006&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/568258/original/file-20240108-16-q7f3ve.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1006&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A plastic model of a mitochondrion.</span>
<span class="attribution"><a class="source" href="https://coimages.sciencemuseumgroup.org.uk/images/24/460/large_2010_0084__0001_.jpg">Science Museum Group Collection © The Board of Trustees of the Science Museum</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
</figcaption>
</figure>
<p>From there, it gets delivered to your cells. Inside your cells are even <a href="https://collection.sciencemuseumgroup.org.uk/objects/co505977/plastic-organelle-model-of-a-mitochondrion-from-a-cell-model-representation">tinier structures called mitochondria</a>, which are the engines that power your entire body. Your mitochondria use the nutrients from food as fuel. But to turn it into energy, they need one more ingredient – oxygen.</p>
<p><a href="https://scholar.google.com/citations?hl=en&user=tuuK7xcAAAAJ">I am a biologist who studies</a> animals and plants. All living things need oxygen, except for <a href="https://en.wikipedia.org/wiki/Obligate_anaerobe">some bacteria</a> and <a href="https://www.doi.org/10.1186/1741-7007-8-30">a few tiny animals</a> that don’t. You might be surprised to learn how many ways there are to get oxygen – breathing is only one of them.</p>
<h2>Lungs and their linings</h2>
<p>When you breathe in, your lungs temporarily trap oxygen, allowing it to pass through very <a href="https://www.britannica.com/science/pulmonary-alveolus">thin surfaces in your lungs</a> into your bloodstream. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/567972/original/file-20240104-19-n4vt7u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A central tube comes down, which then branches and rebranches over and over." src="https://images.theconversation.com/files/567972/original/file-20240104-19-n4vt7u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/567972/original/file-20240104-19-n4vt7u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=603&fit=crop&dpr=1 600w, https://images.theconversation.com/files/567972/original/file-20240104-19-n4vt7u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=603&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/567972/original/file-20240104-19-n4vt7u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=603&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/567972/original/file-20240104-19-n4vt7u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=758&fit=crop&dpr=1 754w, https://images.theconversation.com/files/567972/original/file-20240104-19-n4vt7u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=758&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/567972/original/file-20240104-19-n4vt7u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=758&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A CT scan of healthy lungs.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/healthy-lungs-ct-scan-royalty-free-image/1786377109">RAJAAISYA/Science Photo Library via Getty Images</a></span>
</figcaption>
</figure>
<p>Because you need a lot of oxygen, your lungs need a lot of surface area to do their job. They achieve this by having millions of <a href="https://upload.wikimedia.org/wikipedia/commons/b/bb/Lung_structure_normal.jpg">little air sacs</a> lined with tiny blood vessels called capillaries.</p>
<p>If you could somehow flatten out all the capillary surface area in your lungs, it would more than cover the floor of <a href="https://seatingchartmaker.app/articles/average-classroom-size-square-feet/#classroom-size-by-us-state">an average classroom</a> – around <a href="https://www.sciencedirect.com/topics/engineering/pulmonary-capillary">1,350 square feet (125 square meters)</a>. </p>
<h2>Getting enough oxygen</h2>
<p>If breathing is kind of like eating, why can’t you just take three breaths a day?</p>
<p>One reason is that <a href="https://climate.nasa.gov/news/2915/the-atmosphere-getting-a-handle-on-carbon-dioxide/">air on Earth</a> is only 21% oxygen – the rest is mostly nitrogen. That means you need to take five breaths just to get the equivalent of one complete lungful of oxygen. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/567971/original/file-20240104-14-2jppnf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An illustration depicting the tunnel-like inside of a blood vessel, with vaguely donut-shaped spheres flowing through it." src="https://images.theconversation.com/files/567971/original/file-20240104-14-2jppnf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/567971/original/file-20240104-14-2jppnf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/567971/original/file-20240104-14-2jppnf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/567971/original/file-20240104-14-2jppnf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/567971/original/file-20240104-14-2jppnf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/567971/original/file-20240104-14-2jppnf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/567971/original/file-20240104-14-2jppnf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Your blood can carry only so much oxygen.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/3d-render-of-red-blood-cells-or-corpuscle-flowing-royalty-free-image/1144992100">libre de droit/iStock via Getty Images</a></span>
</figcaption>
</figure>
<p>Also, when you take a breath, only some of the oxygen makes it into your bloodstream. Even though people and many animals make specialized <a href="https://teachchemistry.org/chemmatters/february-2010/the-many-colors-of-blood">proteins to grab and carry oxygen</a>, there’s a limit to how much they can hold at once. To keep your body’s oxygen levels high enough to power all your cells, you need to keep breathing.</p>
<p>Of course, once you breathe in, you also have to breathe out. The gas you breathe out is called <a href="https://learningzone.oumnh.ox.ac.uk/respiration">carbon dioxide</a>. You can think of it as the exhaust from your mitochondria engines, the leftovers once the mitochondria burn oxygen and nutrients to release energy.</p>
<h2>Other animals and plants</h2>
<p>Most living things get oxygen without lungs. </p>
<p>Many aquatic animals use gills, which are sort of like lungs turned inside out. Instead of a bunch of capillaries wrapped around air sacs, <a href="https://theconversation.com/curious-kids-how-do-gills-work-150375">gills are a bunch of capillaries</a> sticking out into the water. Just like in your lungs, the blood vessels take in oxygen from the water and release carbon dioxide.</p>
<p>Insects take in oxygen through a network of little <a href="https://askabiologist.asu.edu/how-insects-breathe">air tubes just under their skin</a>, sort of like the chimneys of a building. This system works because insects are small, so the tubes are already close enough to their cells to give them oxygen. When large insects need extra energy, they <a href="https://askabiologist.asu.edu/how-insects-breathe">pump air through the tubes</a> with their muscles.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/567945/original/file-20240104-28-4qdii8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A microscopic photo showing a green mouth shape." src="https://images.theconversation.com/files/567945/original/file-20240104-28-4qdii8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/567945/original/file-20240104-28-4qdii8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=507&fit=crop&dpr=1 600w, https://images.theconversation.com/files/567945/original/file-20240104-28-4qdii8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=507&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/567945/original/file-20240104-28-4qdii8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=507&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/567945/original/file-20240104-28-4qdii8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=637&fit=crop&dpr=1 754w, https://images.theconversation.com/files/567945/original/file-20240104-28-4qdii8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=637&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/567945/original/file-20240104-28-4qdii8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=637&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A close-up look at the underside of this tomato leaf shows where the air goes in and out.</span>
<span class="attribution"><a class="source" href="https://upload.wikimedia.org/wikipedia/commons/8/85/Tomato_leaf_stomate_cropped_and_scaled.jpg">Vojtěch Dostál</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Plants have <a href="https://www.rhs.org.uk/advice/understanding-plants/how-plants-breathe">little holes in their leaves called stomata</a>. They open and close to let in air when plants need it. Plant roots need oxygen, too, which they usually get from the soil.</p>
<p>You may have heard that plants are the opposite of people: They <a href="https://www.britannica.com/story/do-plants-emit-oxygen-and-carbon-dioxide-at-night">breathe in carbon dioxide and breathe out oxygen</a>. That’s true because carbon dioxide is a crucial ingredient in <a href="https://www.britannica.com/science/photosynthesis">photosynthesis</a> – the process plants use to make their own sugar fuel – and oxygen is a byproduct. But plants’ mitochondria also need oxygen to make energy, just like yours do.</p>
<p>Even though most animals and plants don’t breathe in and out the way people do, they all have ways of getting enough oxygen. Learning how organisms solve the same problem in different ways is one of my favorite things about biology.</p>
<hr>
<p><em>Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to <a href="mailto:curiouskidsus@theconversation.com">CuriousKidsUS@theconversation.com</a>. Please tell us your name, age and the city where you live.</em></p>
<p><em>And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.</em></p><img src="https://counter.theconversation.com/content/219169/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christina S. Baer does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Inhaling air is how you get the oxygen your body needs to turn your food into energy. Other living things use different strategies.
Christina S. Baer, Assistant Professor of Biological Sciences, Binghamton University, State University of New York
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/217025
2023-11-13T21:44:00Z
2023-11-13T21:44:00Z
Gulf of St. Lawrence: Analyzing fish blood can show us how healthy they are
<figure><img src="https://images.theconversation.com/files/557461/original/file-20231003-21-bibw4p.jpeg?ixlib=rb-1.1.0&rect=30%2C12%2C3995%2C3005&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The industrialization of the fishing industry and changes in the environment have raised many issues about the management of our fisheries.</span> <span class="attribution"><span class="source">(Fanny Fronton)</span>, <span class="license">Fourni par l'auteur</span></span></figcaption></figure><p>The Gulf of St. Lawrence is an invaluable resource for Canada. Fish and shellfish fisheries that date to the 16th century have remained an essential source of income for many communities, including those on the North Shore and Gaspésie or the Îles-de-la-Madeleine.</p>
<p>For example, in <a href="https://publications.gc.ca/collections/collection_2019/mpo-dfo/Fs124-10-2018-eng.pdf">Îles-de-la-Madeleine</a>, nearly 1,800 jobs (for a total of 12,500 inhabitants) were linked to fishing in 2015.</p>
<p>But the industrialization of fishing, and changes in the environment, have brought about many new problems in the management of our fisheries. The abundance of different fish species in the Gulf has fluctuated greatly over the last 20 years.</p>
<hr>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><em>This article is part of our series, <a href="https://theconversation.com/ca-fr/topics/fleuve-saint-laurent-116908">The St. Lawrence River: In depth</a>.
Don’t miss new articles on this mythical river of remarkable beauty. Our experts look at its fauna, flora and history, and the issues it faces. This series is brought to you by <a href="https://theconversation.com/ca-fr">La Conversation</a>.</em></p>
<hr>
<p>A case in point: the number of Greenland halibut has declined drastically. This year, <a href="https://www.hi.no/hi/nettrapporter/imr-pinro-en-2023-6">landings</a> are six times lower for fishermen compared to last year.</p>
<p>But other species are benefiting from the situation. This is the case for the population of Atlantic halibut, which is at record levels today.</p>
<p>What is causing these changes? And can we predict further changes?</p>
<p>As a doctoral student in biology at the Institut national de la recherche scientifique (INRS), I am trying to find possible answers to these questions as part of my research work.</p>
<h2>A new health monitoring technique</h2>
<p>The means available for studying the health of fish at the individual level are limited. On the one hand, we can calculate indicators from the weight and height of individual fish. But these measurements are too vague and don’t tell us much.</p>
<p>The logistics of performing biopsies on the tissue of fish — which requires taking samples from their muscle or organs — are complex. To carry them out, researchers must have to travel to the ocean, physically collect samples and bring them back to a laboratory. And then there are ethical considerations, since obviously fish must be sacrificed to achieve this.</p>
<p>Even so, these methods are not very effective for detecting stress induced by environmental changes, and are not effective for detecting stress at early stages, before the physical effects can become manifest.</p>
<p>Yet in a context where the abundance of certain fish species is in rapid decline, an analysis of their overall health is necessary. Fortunately, a new tool is being developed: the <a href="https://www.nature.com/articles/s41598-023-32690-6">circulating microbiome</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/551779/original/file-20231003-15-6ou9xh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="viruses in the blood" src="https://images.theconversation.com/files/551779/original/file-20231003-15-6ou9xh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/551779/original/file-20231003-15-6ou9xh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=343&fit=crop&dpr=1 600w, https://images.theconversation.com/files/551779/original/file-20231003-15-6ou9xh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=343&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/551779/original/file-20231003-15-6ou9xh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=343&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/551779/original/file-20231003-15-6ou9xh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=431&fit=crop&dpr=1 754w, https://images.theconversation.com/files/551779/original/file-20231003-15-6ou9xh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=431&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/551779/original/file-20231003-15-6ou9xh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=431&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">It is often wrongly believed that blood is sterile.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<h2>A little-known practice</h2>
<p>The circulating microbiome is a biomarker, an alarm signal that can be detected in fish even before their health begins to deteriorate. A good biomarker is sensitive, easy to sample, and inexpensive.</p>
<p>The analysis of the circulating microbiome, made up of the DNA of bacteria found in the blood, is directly inspired by <a href="https://theconversation.com/ladn-%20circulating-a-new-simple-and-rapid-weapon-in-the-diagnosis-and-monitoring-of-cancers-206786">similar analyses performed on humans</a>, which provide a great deal of information.</p>
<p>In particular, these analyses make it possible to detect anomalies resulting from the effect of a stress factor on the body, or the development of a disease.</p>
<p>Changes in the environment can also be detected from studying the circulating microbiome. But a major problem emerges here: a fish is not a human. Humans are studied in such detail that knowledge about their health can then be used for an infinite amount of further research. However, sampling fish blood is not a common practice. So there is a great deal that needs to be done before we can properly evaluate the health of fish.</p>
<p>Since the analysis of the circulating microbiome in fish has never been studied before, a lot of work needs to be done to develop the technique.</p>
<h2>Traces of bacteria in the blood?</h2>
<p>As blood circulates throughout the body, it comes into contact specifically with bacteria that make up the other microbiomes (intestinal, oral, dermal). Both in fish and humans, these bacteria are essential for good health.</p>
<p>When we analyze bacterial DNA in the blood, it is therefore possible to find bacteria from the intestine, mouth, or skin. But the hypothesis that these are bacteria specific to the blood cannot be completely ruled out either.</p>
<p>While some continue to believe that blood is sterile, and therefore does not contain any bacteria, we have known since the 1970s that this hypothesis is false — it was confirmed <a href="https://doi.org/10.1128/jcm.39.5.1956-1959.2001">in the 2000s by genomic studies</a>. It’s possible that in 1674, the Dutch microbiologist Antonie Van Leeuwenhoek may even have observed bacteria in salmon blood <a href="https://doi.org/10.3389/fcimb.2019.00148">under a microscope</a>.</p>
<p>Today, we can analyze these bacteria in detail by targeting a very specific bacterial gene, the 16S ribosomal RNA gene. Present in all bacteria around the world, this gene varies slightly from one species to another. That makes it possible to identify and analyze the biodiversity of the microbiome.</p>
<h2>I eat, therefore I am</h2>
<p>Our recent work has made it possible to characterize, for the first time, the <a href="https://www.nature.com/articles/s41598-023-32690-6">circulating microbiomes of turbot and halibut</a>. We have demonstrated that the two fish species have circulating microbiomes dominated by the presence of the species <em>Pseudoalteromonas</em> and <em>Psychrobacter</em>. These bacteria are known to colonize cold environments, for example the bottom of the Gulf of St. Lawrence, which is around 5°C. They are also known to produce bioactive compounds (antibacterials and antifungals). They are more tenacious than other bacteria.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/551768/original/file-20231003-29-qhulgz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="person with blue gloves holds a fish" src="https://images.theconversation.com/files/551768/original/file-20231003-29-qhulgz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/551768/original/file-20231003-29-qhulgz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/551768/original/file-20231003-29-qhulgz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/551768/original/file-20231003-29-qhulgz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/551768/original/file-20231003-29-qhulgz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/551768/original/file-20231003-29-qhulgz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/551768/original/file-20231003-29-qhulgz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Greenland halibut.</span>
<span class="attribution"><span class="source">(Fanny Fronton)</span>, <span class="license">Fourni par l'auteur</span></span>
</figcaption>
</figure>
<p>However, differences can be observed between the two species. Turbot has more bacteria called <em>Vibrio</em>, some of which metabolize chitin, a molecule that makes up the shells of the invertebrates on which it feeds. Atlantic halibut, for its part, presents more <em>Acinetobacter</em> bacteria, typical of piscivorous (fish-eating) diets in the intestinal microbiomes. The circulating microbiome in these two fish species therefore seems to be influenced by intestinal bacteria, as is the case in humans. We could therefore potentially link a blood microbiome to the fish’s diet, which is often difficult to estimate.</p>
<h2>An embryonic, but promising technique</h2>
<p>So this first bacterial mapping of the blood of these two species probably reflects their respective intestinal microbiome. From this characterization, detection of a variation in the composition of bacteria could be linked to stress, a change in the environment or a physiological change in the animal.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/540859/original/file-20230802-23891-ctgz3u.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="comic strip" src="https://images.theconversation.com/files/540859/original/file-20230802-23891-ctgz3u.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/540859/original/file-20230802-23891-ctgz3u.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=907&fit=crop&dpr=1 600w, https://images.theconversation.com/files/540859/original/file-20230802-23891-ctgz3u.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=907&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/540859/original/file-20230802-23891-ctgz3u.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=907&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/540859/original/file-20230802-23891-ctgz3u.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1140&fit=crop&dpr=1 754w, https://images.theconversation.com/files/540859/original/file-20230802-23891-ctgz3u.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1140&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/540859/original/file-20230802-23891-ctgz3u.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1140&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Comic strip illustrating the principle of analyzing the circulating microbiome.</span>
<span class="attribution"><span class="source">(Fanny Fronton)</span>, <span class="license">Fourni par l'auteur</span></span>
</figcaption>
</figure>
<p>For example, we know that in humans, the loss of <em>Actinobacteria</em> in the circulating microbiome is associated with severe acute <a href="https://doi.org/10.3389/fcimb.2018.00005">pancreatitis</a>. And there are dozens of examples like this in humans.</p>
<p>This study, the result of a collaboration between university researchers from INRS, the University of Québec at Rimouski and the Department of Fisheries and Oceans Canada, provides a small overview of the informative potential offered by the blood microbiomes of fish from the Gulf of St. Lawrence.</p>
<p>Further research will make it possible to estimate their health and better predict the evolution of their population. The dramatic collapse of the cod stock in the late 1980s had a major impact on fishermen. Several of them even fear that this situation will happen again with another species. As turbot remains a species at risk, it is essential to ensure better management of St. Lawrence species.</p>
<p>Only by refining our analysis techniques and deepening our scientific knowledge can we prevent this type of collapse from happening again in the future.</p><img src="https://counter.theconversation.com/content/217025/count.gif" alt="La Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Fanny Fronton received a grant from the Fondation Armand Frappier.</span></em></p>
Blood isn’t sterile, and analyzing the bacteria in it could help assess the health of fish and prevent the collapse of their populations.
Fanny Fronton, Doctorante en Écologie halieutique et biologie moléculaire, Institut national de la recherche scientifique (INRS)
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/214622
2023-10-12T12:31:00Z
2023-10-12T12:31:00Z
Horseshoe crab blood is vital for testing intravenous drugs, but new synthetic alternatives could mean pharma won’t bleed this unique species dry
<figure><img src="https://images.theconversation.com/files/552874/original/file-20231010-19-onfdw4.jpg?ixlib=rb-1.1.0&rect=33%2C8%2C5579%2C3728&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Horseshoe crabs in spawning season at Reeds Beach, N.J., on June 13, 2023.</span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/HorseshoeCrabHarvest/053d4f924f9c453f808a4d3724a87e73/photo">AP Photo/Matt Rourke</a></span></figcaption></figure><p>If you have ever gotten a vaccine or received an intravenous drug and did not come down with a potentially life-threatening fever, you can thank a horseshoe crab (<em>Limulus polyphemus</em>).</p>
<p>How can animals that are <a href="https://www.britannica.com/animal/horseshoe-crab">often called living fossils</a>, because they have barely changed over millions of years, be so important in modern medicine? Horseshoe crab blood is used to produce a substance called limulus amebocyte lysate, or LAL, which scientists use to test for <a href="https://www.britannica.com/science/endotoxin">toxic substances called endotoxins</a> in intravenous drugs. </p>
<p>These toxins, produced by bacteria, are ubiquitous in the environment and can’t be removed simply through sterilization. They can cause a reaction historically referred to as “<a href="https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/inspection-technical-guides/pyrogens-still-danger">injection fever</a>.” A strong concentration can lead to shock and even death. </p>
<p>Identifying LAL as a highly sensitive detector of endotoxins was a 20th-century medical safety breakthrough. Now, however, critics are raising questions about environmental impacts and the process for reviewing and approving synthetic alternatives to horseshoe crab blood.</p>
<p>We study <a href="https://scholar.google.com/citations?user=Dd_T980AAAAJ&hl=en&authuser=1&oi=ao">science, technology</a> and <a href="https://www.linkedin.com/in/jolie-crunelle/%20student">public policy</a>, and recently published a <a href="https://osf.io/3tm9g/">white paper</a> examining social, political and economic issues associated with using horseshoe crabs to produce LAL. We see this issue as a test case for complicated problems that cut across multiple agencies and require attention to both nature and human health.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/CgRn3T7vcMw?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Protecting horseshoe crabs will require persuading the heavily regulated pharmaceutical industry to embrace change.</span></figcaption>
</figure>
<h2>An ocean solution</h2>
<p>Doctors began injecting patients with various solutions <a href="https://doi.org/10.1016/j.socscimed.2004.06.044">in the mid-1800s</a>, but it was not until the 1920s that biochemist <a href="https://lemelson.mit.edu/resources/florence-seibert">Florence Seibert</a> discovered that febrile reactions were due to contaminated water in these solutions. She created a method for detecting and removing the substances that caused this reaction, and it became the medical standard in the 1940s.</p>
<p>Known as the <a href="https://www.matresearch.com/pyrogen-testing/">rabbit pyrogen test</a>, it required scientists to inject intravenous drugs into rabbits, then monitor the animals. A feverish rabbit meant that a batch of drugs was contaminated.</p>
<p>The LAL method was discovered by accident. Working with horseshoe crabs at the <a href="https://www.mbl.edu/">Marine Biological Laboratory</a> at Woods Hole, Massachusetts, in the 1950s and ’60s, <a href="https://www.goldengooseaward.org/01awardees/horseshoe-crab-blood">pathobiologist Frederik Bang and medical researcher Jack Levin</a> noticed that the animals’ <a href="https://hub.jhu.edu/magazine/2021/summer/horseshoe-crabs-covid19-medical-uses/">blue blood</a> coagulated in a curious manner. Through a series of experiments, they isolated endotoxin as the coagulant and devised a method for extracting LAL from the blood. This compound would gel or clot nearly instantaneously in the presence of fever-inducing toxins.</p>
<p>Academic researchers, biomedical companies and the U.S. Food and Drug Administration refined LAL production and measured it against the rabbit test. By the 1990s, LAL was the <a href="https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/inspection-technical-guides/bacterial-endotoxinspyrogens">FDA-approved method</a> for testing medicines for endotoxin, largely replacing rabbits.</p>
<p>Producing LAL requires harvesting horseshoe crabs from oceans and beaches, <a href="https://www.theatlantic.com/technology/archive/2014/02/the-blood-harvest/284078/">draining up to 30% of their blood</a> in a laboratory and returning the live crabs to the ocean. There’s dispute about <a href="https://www.scientificamerican.com/article/medical-labs-may-be-killing-horseshoe-crabs/">how many crabs die in the process</a> – estimates range from a few percent to 30% or more – and about possible harmful effects on survivors. </p>
<p>Today there are five FDA-licensed <a href="https://asmfc.org/uploads/file/645bf065HSC_Biomedical_BMPs_2023.pdf">LAL producers</a> along the U.S. East Coast. The amount of LAL they produce, and its sales value, are proprietary. </p>
<h2>Bait versus biotech</h2>
<p>As biomedical LAL production ramped up in the 1990s, so did harvesting horseshoe crabs to use as bait for other species, particularly eel and whelk for foreign seafood markets. Over the past 25 years, hundreds of thousands – and in the early years, millions – of horseshoe crabs have been harvested each year for these purposes. Combined, the two fisheries kill <a href="https://asmfc.org/species/horseshoe-crab">over half a million</a> horseshoe crabs every year.</p>
<p>There’s no agreed total population estimate for <em>Limulus</em>, but the most recent <a href="https://asmfc.org/uploads/file/63d2ed62HSCAssessment_PeerReviewReport_May2019.pdf">federal assessment of horseshoe crab fisheries</a> found the population was neither strongly growing nor declining.</p>
<p>Conservationists are worried, and not just about the crabs. Millions of shorebirds <a href="https://atlanticflywayshorebirds.org/">migrate along the Atlantic coast</a>, and many stop in spring, when horseshoe crabs spawn on mid-Atlantic beaches, to feed on the crabs’ eggs. Particularly for <a href="https://www.allaboutbirds.org/guide/Red_Knot/overview">red knots</a> – a species that can migrate up to 9,000 miles between the tip of South America and the Canadian Arctic – gorging on horseshoe crab eggs provides a critical energy-rich boost on their grueling journey.</p>
<p>Red knots were <a href="https://www.federalregister.gov/documents/2014/12/11/2014-28338/endangered-and-threatened-wildlife-and-plants-threatened-species-status-for-the-rufa-red-knot">listed as threatened</a> under the Endangered Species Act in 2015, largely because horseshoe crab fishing threatened this key food source. As biomedical crab harvests came to equal or <a href="https://asmfc.org/species/horseshoe-crab">surpass bait harvests</a>, conservation groups began calling on the LAL industry to find new sources.</p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/Ct2Aji4xcPJ/?utm_source=ig_web_copy_link\u0026igshid=MzRlODBiNWFlZA==","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<h2>Biomedical alternatives</h2>
<p>Many important medicines are derived from living organisms. Penicillin, the first important antibiotic, was <a href="https://www.sciencemuseum.org.uk/objects-and-stories/how-was-penicillin-developed">originally produced from molds</a>. Other medicines currently in use come from sources including <a href="https://www.goodrx.com/well-being/diet-nutrition/medications-that-contain-animal-byproducts">cows, pigs, chickens and fish</a>. The ocean is a <a href="https://oceanexplorer.noaa.gov/facts/medicinesfromsea.html">promising source</a> for such products.</p>
<p>When possible, synthesizing these substances in laboratories – especially widely used medications like <a href="https://www.cityofhope.org/breakthroughs/art-riggs-tribute">insulin</a> – offers many benefits. It’s typically cheaper and more efficient, and it avoids putting species at risk, as well as addressing <a href="https://www.uspharmacist.com/article/animal-derived-medications-can-be-problematic-for-some-patients">concerns some patients have</a> about using animal-derived medical products.</p>
<p>In the 1990s, researchers at the National University of Singapore <a href="https://patents.google.com/patent/WO1999015676A1/en?inventor=Jeak+Ling+Ding">invented and patented</a> the first process for creating a synthetic, endotoxin-detecting compound using horseshoe crab DNA and <a href="https://www.genome.gov/genetics-glossary/Recombinant-DNA-Technology">recombinant DNA technology</a>. The result, dubbed recombinant Factor C (rFC), mimicked the first step in the three-part cascade reaction that occurs when LAL is exposed to endotoxin. </p>
<p>Later, several biomedical firms <a href="https://www.americanpharmaceuticalreview.com/Featured-Articles/569887-Historical-Milestones-and-Industry-Drivers-in-the-Development-of-Recombinant-Lysate-for-Bacterial-Endotoxin-Testing/">produced their own versions</a> of rFC and compounds called recombinant cascade reagents (rCRs), which reproduce the entire LAL reaction without using horseshoe crab blood. Yet, today, LAL remains the dominant technology for detecting endotoxins in medicine. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/552876/original/file-20231010-22-ilv12l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A vial partly filled with pale blue fluid" src="https://images.theconversation.com/files/552876/original/file-20231010-22-ilv12l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/552876/original/file-20231010-22-ilv12l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/552876/original/file-20231010-22-ilv12l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/552876/original/file-20231010-22-ilv12l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/552876/original/file-20231010-22-ilv12l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/552876/original/file-20231010-22-ilv12l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/552876/original/file-20231010-22-ilv12l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A sample of horseshoe crab blood.</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/riAZsU">Florida Fish and Wildlife Commission</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>The main reason is that the <a href="https://www.usp.org/">U.S. Pharmacopeia</a>, a quasi-regulatory organization that sets safety standards for medical products, considers rFC and rCR as “alternative” methods for detecting endotoxins, so they require case-by-case validation for use – a potentially lengthy and expensive process. The FDA generally defers to the U.S. Pharmacopeia.</p>
<p>A few large pharmaceutical companies with deep pockets have committed to <a href="https://www.esg.lilly.com/environmental/biodiversity?redirect-referrer=https%3A%2F%2Fwww.google.com%2F#case-studies">switching from LAL to rFC</a>. But most drug producers are sticking with the tried-and-true method. </p>
<p>Conservation groups want the U.S. Pharmacopeia to <a href="https://www.audubon.org/magazine/summer-2018/inside-biomedical-revolution-save-horseshoe-crabs">fully certify rFC</a> for use in industry with no extra testing or validation. In their view, LAL producers are stalling rFC and rCR approval to protect their <a href="https://www.npr.org/2023/06/10/1180761446/coastal-biomedical-labs-are-bleeding-more-horseshoe-crabs-with-little-accountabi">market in endotoxin detection</a>. The U.S. Pharmacopeia and LAL producers counter that they are doing due diligence to <a href="https://hsc.criver.com/#lal-endo">protect public health</a>.</p>
<h2>Change in the offing</h2>
<p>Change may be coming. All major LAL producers now have their own recombinant products – a tacit acknowledgment that markets and regulations are moving toward <em>Limulus</em>-free ways to test for endotoxins. </p>
<p>Atlantic fisheries regulators are currently considering <a href="https://www.asmfc.org/home/2023-annual-meeting">new harvest limits for horseshoe crabs</a>, and the U.S. Pharmacopeia is <a href="https://www.uspnf.com/notices/86-bet-using-recombinant-tests-gen-annc-20230822">weighing guidance</a> on recombinant alternatives to LAL. Public comments will be solicited over the winter of 2024, followed by U.S. Pharmacopeia and FDA review. </p>
<p>Even if rFC and rCR don’t win immediate approval, we believe that collecting more complete data on horseshoe crab populations and requiring more transparency from the LAL industry on <a href="https://asmfc.org/uploads/file/645bf065HSC_Biomedical_BMPs_2023.pdf">how it handles the crabs</a> would represent progress. So would directing medical companies to use recombinant products for testing during the manufacturing process, while saving LAL solely for final product testing. </p>
<p>Making policy on complex scientific issues across diverse agencies is never easy. But in our view, incremental actions that protect both human health and the environment could be important steps forward.</p><img src="https://counter.theconversation.com/content/214622/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>This material is based upon work supported by the National Science Foundation under Award No. 2121146, as well as the Leverhulme Trust through a Leverhulme Trust Research Project Grant. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation or the Leverhulme Trust.</span></em></p><p class="fine-print"><em><span>Jolie Crunelle receives funding from the Aberg Family Fellowship at Rochester Institute of Technology. </span></em></p>
Horseshoe crabs play a unique role in medicine, but they’re also ecologically important in their home waters along the Atlantic coast. Can regulators balance the needs of humans and nature?
Kristoffer Whitney, Associate Professor of Science, Technology and Society, Rochester Institute of Technology
Jolie Crunelle, Master's Degree Student in Science, Technology, and Public Policy, Rochester Institute of Technology
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/215166
2023-10-09T12:17:28Z
2023-10-09T12:17:28Z
Centenarian blood tests give hints of the secrets to longevity
<figure><img src="https://images.theconversation.com/files/552718/original/file-20231009-28-ftpqy8.jpg?ixlib=rb-1.1.0&rect=103%2C17%2C3725%2C2132&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/portrait-hundred-years-old-woman-centenarian-1022974105">Dan Negureanu/Shutterstock</a></span></figcaption></figure><p>Centenarians, once considered rare, have become commonplace. Indeed, they are the <a href="https://www.weforum.org/agenda/2021/02/living-to-one-hundred-life-expectancy/">fastest-growing demographic group</a> of the world’s population, with numbers roughly doubling every ten years since the 1970s.</p>
<p>How long humans can live, and what determines a long and healthy life, have been of interest for as long as we know. Plato and Aristotle discussed and <a href="https://pubmed.ncbi.nlm.nih.gov/12092789/">wrote about the ageing process</a> over 2,300 years ago. </p>
<p>The pursuit of understanding the secrets behind exceptional longevity isn’t easy, however. It involves <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7105197/">unravelling the complex interplay</a> of genetic predisposition and lifestyle factors and how they interact throughout a person’s life. Now our recent study, <a href="https://link.springer.com/article/10.1007/s11357-023-00936-w">published in GeroScience</a>, has unveiled some common biomarkers, including levels of cholesterol and glucose, in people who live past 90.</p>
<p>Nonagenarians and centenarians have long been of intense interest to scientists as they may help us understand how to live longer, and perhaps also how to age in better health. So far, studies of centenarians have often been small scale and focused on a selected group, for example, excluding centenarians who live in care homes. </p>
<h2>Huge dataset</h2>
<p>Ours is the largest study comparing biomarker profiles measured throughout life among exceptionally long-lived people and their shorter-lived peers to date. </p>
<p>We compared the biomarker profiles of people who went on to live past the age of 100, and their shorter-lived peers, and investigated the link between the profiles and the chance of becoming a centenarian. </p>
<p>Our research included data from 44,000 Swedes who underwent health assessments at ages 64-99 - they were a sample of <a href="https://pubmed.ncbi.nlm.nih.gov/28158674/">the so-called Amoris cohort</a>. These participants were then followed through Swedish register data for up to 35 years. Of these people, 1,224, or 2.7%, lived to be 100 years old. The vast majority (85%) of the centenarians were female. </p>
<p>Twelve blood-based biomarkers related to inflammation, metabolism, liver and kidney function, as well as potential malnutrition and anaemia, were included. All of these <a href="https://www.nature.com/articles/s41591-019-0719-5">have been associated</a> with ageing or mortality in previous studies.</p>
<p>The biomarker related to inflammation was uric acid – a waste product in the body caused by the digestion of certain foods. We also looked at markers linked to metabolic status and function including total cholesterol and glucose, and ones related to liver function, such as alanine aminotransferase (Alat), aspartate aminotransferase (Asat), albumin, gamma-glutamyl transferase (GGT), alkaline phosphatase (Alp) and lactate dehydrogenase (LD). </p>
<p>We also looked at creatinine, which is linked to kidney function, and iron and total iron-binding capacity (TIBC), which is linked to anaemia. Finally, we also investigated albumin, a biomarker associated with nutrition. </p>
<h2>Findings</h2>
<p>We found that, on the whole, those who made it to their hundredth birthday tended to have lower levels of glucose, creatinine and uric acid from their sixties onwards. Although the median values didn’t differ significantly between centenarians and non-centenarians for most biomarkers, centenarians seldom displayed extremely high or low values.</p>
<p>For example, very few of the centenarians had a glucose level above 6.5 earlier in life, or a creatinine level above 125.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/552719/original/file-20231009-27-cn0vqz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Image of Villagrande Strisaili in the Ogliastra Province of Sardinia, Italy, which has the world's highest population of centenarian men." src="https://images.theconversation.com/files/552719/original/file-20231009-27-cn0vqz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/552719/original/file-20231009-27-cn0vqz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/552719/original/file-20231009-27-cn0vqz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/552719/original/file-20231009-27-cn0vqz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/552719/original/file-20231009-27-cn0vqz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/552719/original/file-20231009-27-cn0vqz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/552719/original/file-20231009-27-cn0vqz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Villagrande Strisaili in the Ogliastra Province of Sardinia, Italy, has the world’s highest population of centenarian men.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/villagrande-strisaili-italy-october-2019-scenic-1543489556">Sabino Parente/Shutterstock</a></span>
</figcaption>
</figure>
<p>For many of the biomarkers, both centenarians and non-centenarians had values outside of the range considered normal in clinical guidelines. This is probably because these guidelines are set based on a younger and healthier population. </p>
<p>When exploring which biomarkers were linked to the likelihood of reaching 100, we found that all but two (alat and albumin) of the 12 biomarkers showed a connection to the likelihood of turning 100. This was even after accounting for age, sex and disease burden. </p>
<p>The people in the lowest out of five groups for levels of total cholesterol and iron had a lower chance of reaching 100 years as compared to those with higher levels. Meanwhile, people with higher levels of glucose, creatinine, uric acid and markers for liver function also decreased the chance of becoming a centenarian. </p>
<p>In absolute terms, the differences were rather small for some of the biomarkers, while for others the differences were somewhat more substantial.</p>
<p>For uric acid, for instance, the absolute difference was 2.5 percentage points. This means that people in the group with the lowest uric acid had a 4% chance of turning 100 while in the group with the highest uric acid levels only 1.5% made it to age 100.</p>
<p>Even if the differences we discovered were overall rather small, they suggest a potential link between metabolic health, nutrition and exceptional longevity. </p>
<p>The study, however, does not allow any conclusions about which lifestyle factors or genes are responsible for the biomarker values. However, it is reasonable to think that factors such as nutrition and alcohol intake play a role. Keeping track of your kidney and liver values, as well as glucose and uric acid as you get older, is probably not a bad idea.</p>
<p>That said, chance probably plays a role at some point in reaching an exceptional age. But the fact that differences in biomarkers could be observed a long time before death suggests that genes and lifestyle may also play a role.</p><img src="https://counter.theconversation.com/content/215166/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Karin Modig receives funding from The Swedish Research Council and Swedish Research Council for Health, Working Life, and Welfare.</span></em></p>
Centenarians tend to have lower levels of glucose, creatinine and uric acid from their sixties onwards.
Karin Modig, Associate Professor, Epidemiology, Karolinska Institutet
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/201871
2023-06-27T02:14:36Z
2023-06-27T02:14:36Z
How do I insert a tampon?
<figure><img src="https://images.theconversation.com/files/532313/original/file-20230616-19-ay9uyd.jpg?ixlib=rb-1.1.0&rect=10%2C0%2C3320%2C1705&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">pexels sora shimazaki</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>If you’ve just decided to start using tampons and you’re finding it tricky, you’re not alone! Lots of young teens and first-time tampon users have told me they experience “tampon trauma” – meaning it hurts, won’t go in or gets stuck coming out. But with a little bit of practice, it’s super easy.</p>
<p>Tampons are safe and convenient, especially if you’re going to the beach, swimming or doing something physically active. You can’t feel a tampon once it’s inserted properly, which is why some people prefer tampons to pads or period undies. Tampons are used by <a href="https://www.nationalgeographic.com/environment/article/how-tampons-pads-became-unsustainable-story-of-plastic#:%7E:text=Did%20You%20Know%3F,-Usage&text=Recycling-,5.8%20billion%20tampons%20were%20sold%20in%20the%20U.S.%20in%202018,ocean%20when%20sewer%20systems%20fail.">millions of people</a> around the world. They’re made from natural cotton, rayon fibre or both, and absorb fluid, including menstrual blood. </p>
<p>In Australia, tampons are classified as “medical devices” which means they have to meet certain safety standards. So even though there’s a confusing array of brands available in Australia it’s good to know they all pass the safety test.</p>
<p>Just like pads and period undies, tampons come with different absorbencies, such as “mini” or “light”, “regular” and “super”. As you get to know your own periods and cycle, you’ll also get to know which tampons suit you best over the course of your period. It’s common for the first couple of days of a period to be heavier, meaning you might need a tampon with higher absorbency.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/menstrual-cups-vs-tampons-heres-how-they-compare-120499">Menstrual cups vs tampons – here's how they compare</a>
</strong>
</em>
</p>
<hr>
<h2>How to insert</h2>
<p>A tampon is designed to sit inside the vagina, right up high against the cervix. The vagina is a stretchy muscular tube and has plenty of room to accommodate a tampon. </p>
<p>The vagina slopes upward and backward, towards the spine. A common difficulty first-time tampon users encounter is pushing the tampon straight up rather than slightly backwards, so it hits the front wall of the vagina and feels like it can’t go up any further. The same can happen in reverse when pulling a tampon out – it needs to be pulled slightly forward, not straight down, or it could hit the back wall of the vagina and feel stuck.</p>
<p>If you want to, you can practise using a tampon between your periods, or when your flow is light. Wash your hands first, then get a mini-sized tampon and make it slippery by putting some water-based lubricant on it. Some people might dab a tiny bit of Vaseline on the tip of the tampon instead. Vaseline shouldn’t be put on tampons during a period, as it reduces absorbency. </p>
<p>Pull the string so it reaches its full length before you insert it. Stand in front of a mirror and have a look at where the opening of your vagina is by pulling the vaginal lips apart. Then either squat, or put one leg up on a stool, shelf, or side of the bath, which gets you in a comfortable position to practise. </p>
<p>Gently put the tip of the tampon into the opening and then push it up and back with your finger. You can put your fingers inside your vagina first, to get a feel of the way your vagina slopes. (If you have long nails, take care not to scratch yourself!)</p>
<p><iframe id="tc-infographic-879" class="tc-infographic" height="400px" src="https://cdn.theconversation.com/infographics/879/daa47e958c4391e8fa586f1fc90bb0554872c2d7/site/index.html" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>Some tampons come with an “applicator”. This is made of two cardboard or plastic tubes, one inside the other. The larger tube has the tampon inside it, and the smaller one sits just below the tampon. When inserting, you hold the smaller part and push the applicator inside your vagina rather than putting your fingers inside. When the applicator has gone all the way in, you push the tampon out by “plunging” the smaller tube up, pushing the tampon out. </p>
<p>It’s virtually impossible to put a tampon into the wrong hole! There are three holes in that part of the body – the vagina, the urethra (where wee comes out) and the anus, or bum hole, where poo comes out. Most people are familiar with where the bum hole is, because (hopefully) they wipe their bums a lot! </p>
<p>The urethra is very small, and you wouldn’t be able to fit a tampon into it. It sits high up towards the top of the vulva – where your inner vaginal lips meet in the middle, and just below the tip of the clitoris.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/533054/original/file-20230621-20-ocbi2q.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Diagram showing a vulva" src="https://images.theconversation.com/files/533054/original/file-20230621-20-ocbi2q.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/533054/original/file-20230621-20-ocbi2q.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=561&fit=crop&dpr=1 600w, https://images.theconversation.com/files/533054/original/file-20230621-20-ocbi2q.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=561&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/533054/original/file-20230621-20-ocbi2q.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=561&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/533054/original/file-20230621-20-ocbi2q.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=704&fit=crop&dpr=1 754w, https://images.theconversation.com/files/533054/original/file-20230621-20-ocbi2q.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=704&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/533054/original/file-20230621-20-ocbi2q.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=704&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Vulva diagram.</span>
<span class="attribution"><span class="source">The Conversation</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Tampons can be left in for up to six hours. If your period is heavier than anticipated and the tampon has become “soaked”, you might have to change it earlier. You’ll know when that happens because some menstrual fluid will leak onto your undies. </p>
<p>Don’t panic though – it’s something you’ll be able to feel and deal with before anyone else notices! If you know you have heavy flow days and want to take extra precautions, you can wear a light pad on your undies (or period undies) as well as using a tampon. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/heavy-periods-are-common-what-can-you-do-and-when-should-you-seek-help-191511">Heavy periods are common. What can you do, and when should you seek help?</a>
</strong>
</em>
</p>
<hr>
<h2>Toxic shock syndrome</h2>
<p>You might have heard about something called Toxic Shock Syndrome. This is caused by a bacterial infection that releases toxins into the blood and is a serious condition. </p>
<p>It can happen anywhere in the body but is known to be associated with the use of ultra super absorbency tampons. There are now guidelines and regulations worldwide for tampon manufacturing to reduce the risk of infections. </p>
<p>These days toxic shock syndrome is extremely rare (about <a href="https://my.clevelandclinic.org/health/diseases/15437-toxic-shock-syndrome#:%7E:text=Toxic%20shock%20syndrome%20affects%201,absorbent%20tampons%20during%20their%20period.">0.001%</a> of people), and still only occurs if tampons are left in for several hours, allowing the bacteria to multiply. </p>
<p>Symptoms are high fever, vomiting, diarrhoea, muscle aches, headaches and a rash.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/from-sharp-butt-pains-to-period-poos-5-lesser-known-menstrual-cycle-symptoms-191352">From sharp butt pains to period poos: 5 lesser-known menstrual cycle symptoms</a>
</strong>
</em>
</p>
<hr>
<h2>Environmentally friendly options</h2>
<p>It’s important to NEVER flush a tampon down the toilet. If you’re in a public toilet, there should be bins inside toilet cubicles for all disposable period products. At home, you could wrap it in tissue and put it in a rubbish bin. You might also be aware people are now looking at environmentally friendly alternatives to disposable pads and tampons. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/532314/original/file-20230616-21-1p38kv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Woman throwing a used tampon into a bin" src="https://images.theconversation.com/files/532314/original/file-20230616-21-1p38kv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532314/original/file-20230616-21-1p38kv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532314/original/file-20230616-21-1p38kv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532314/original/file-20230616-21-1p38kv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532314/original/file-20230616-21-1p38kv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532314/original/file-20230616-21-1p38kv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532314/original/file-20230616-21-1p38kv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Never flush a tampon down the toilet, put it in a bin.</span>
<span class="attribution"><span class="source">Pexels/Karolina Grabowska</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Reusable pads and period undies were designed to help reduce waste from disposable pads. There’s now also an alternative to tampons, which is the modern “menstrual cup”. These are made of medical grade silicone that you fold over, push up inside your vagina using two fingers, and then pop! It springs open inside the vagina and catches any menstrual fluid. </p>
<p>Unlike a tampon, they sit a little lower down in the vagina, and just like tampons, they can take practice getting used to. These can be used for up to 12 hours which makes them super convenient. You can try a menstrual cup anytime – and some people might switch between tampons and a cup or pads or period undies, depending on what feels right on the day.</p>
<p>Managing periods is something almost half the population deals with. It can feel scary, but it might help to know that just about everyone who has periods goes through the same process of figuring it out! The more you arm yourself with information and know how much choice is out there, the more confident you’ll feel. And don’t forget there are always adults out there who are willing and able to give you advice and help. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-queues-for-womens-toilets-are-longer-than-mens-99763">Why queues for women's toilets are longer than men's</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/201871/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Melissa Kang has received funding from the National Health and Medical Research Councill, Australian Research Council and Medical Research Futures Fund. She is affiliated with the Australian Association for Adolescent Health and the International Association for Adolescent Health. She has co-authored Welcome to Your Period, Welcome to Consent, Welcome to Your Boobs and Welcome to Sex.</span></em></p>
Lots of young teens and first-time tampon users are intimidated by tampons. But they’re easy once you get the hang of it.
Melissa Kang, Associate Professor, University of Sydney
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/205556
2023-06-14T12:35:28Z
2023-06-14T12:35:28Z
Forensic evidence suggests Paleo-Americans hunted mastodons, mammoths and other megafauna in eastern North America 13,000 years ago
<figure><img src="https://images.theconversation.com/files/528316/original/file-20230525-21-no8djo.jpg?ixlib=rb-1.1.0&rect=556%2C160%2C3570%2C2456&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Animals that shared the landscape with humans disappeared as the ice age ended.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Ice_age_fauna_of_northern_Spain_-_Mauricio_Antón.jpg">Mauricio Antón/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>The earliest people who lived in North America shared the landscape with huge animals. On any day these hunter-gatherers might encounter a giant, snarling saber-toothed cat ready to pounce, or a group of elephantlike mammoths stripping tree branches. Maybe a herd of giant bison would stampede past.</p>
<p>Obviously, you can’t see any of these ice age megafauna now. They’ve all been extinct for about 12,800 years. Mammoths, mastodons, huge bison, horses, camels, very large ground sloths and giant short-faced bears all died out as the huge continental ice sheets disappeared at the end of the ice age. What happened to them?</p>
<p>Scientists have pointed to various potential causes for the extinctions. Some suggest <a href="https://doi.org/10.1038/s41467-021-21201-8">environmental changes happened faster</a> than the animals could adapt to them. Others posit a <a href="https://doi.org/10.1073/pnas.0706977104">catastrophic impact of a fragmented comet</a>. Maybe it was <a href="https://doi.org/10.1073/pnas.0501947102">overhunting on the part of humans</a>, or <a href="https://doi.org/10.1146/annurev.ecolsys.34.011802.132415">some combination of all these factors</a>.</p>
<p><a href="https://sc.edu/study/colleges_schools/artsandsciences/sc_institute_archeology_and_anthropology/faculty-staff/moore_christopher.php">One of my major interests as an archaeologist</a> has been to understand how the earliest Paleo-Americans lived and interacted with megafauna species. Just how implicated should humans be in the extinction of these ice age animals? In a new study, my colleagues and I used a forensic technique more commonly used to identify blood on objects at crime scenes <a href="https://doi.org/10.1038/s41598-023-36617-z">to investigate this question</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/528320/original/file-20230525-19-5p0no3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Artist's rendition of Paleoamerican Clovis encampment with people sitting around campfire under night sky" src="https://images.theconversation.com/files/528320/original/file-20230525-19-5p0no3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/528320/original/file-20230525-19-5p0no3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=420&fit=crop&dpr=1 600w, https://images.theconversation.com/files/528320/original/file-20230525-19-5p0no3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=420&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/528320/original/file-20230525-19-5p0no3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=420&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/528320/original/file-20230525-19-5p0no3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=528&fit=crop&dpr=1 754w, https://images.theconversation.com/files/528320/original/file-20230525-19-5p0no3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=528&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/528320/original/file-20230525-19-5p0no3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=528&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Clovis hunter-gatherers lived in small, mobile groups, likely following animal migrations over long distances.</span>
<span class="attribution"><span class="source">Martin Pate/Southeast Archeological Center, National Park Service</span></span>
</figcaption>
</figure>
<h2>Testing stone tools like murder weapons</h2>
<p>Archaeologists have uncovered a sparse scattering of stone tools left at the campsites of Paleo-American Clovis hunter-gatherers who lived around the time of the megafauna extinctions. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/531835/original/file-20230614-25-wuuy96.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="line drawing of two stone points" src="https://images.theconversation.com/files/531835/original/file-20230614-25-wuuy96.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/531835/original/file-20230614-25-wuuy96.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=682&fit=crop&dpr=1 600w, https://images.theconversation.com/files/531835/original/file-20230614-25-wuuy96.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=682&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/531835/original/file-20230614-25-wuuy96.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=682&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/531835/original/file-20230614-25-wuuy96.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=857&fit=crop&dpr=1 754w, https://images.theconversation.com/files/531835/original/file-20230614-25-wuuy96.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=857&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/531835/original/file-20230614-25-wuuy96.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=857&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Early Paleo-American Clovis points (left) and Middle Paleo-American redstone points (right) have a distinct fluted shape, highlighted in yellow, likely designed to facilitate hafting onto a spear or knife handle for use in hunting and butchery.</span>
<span class="attribution"><span class="source">Darby Erd</span></span>
</figcaption>
</figure>
<p>These include iconic <a href="https://www.britannica.com/topic/Clovis-complex">Clovis spearpoints</a> with their distinctive flutes – concave areas left behind by removed stone flakes that extend from the base to the middle of the point. People most likely made the points this way so they could easily affix them to a spear shaft.</p>
<p>Based on <a href="https://www.heritagedaily.com/2016/02/an-afternoon-walk-and-a-mammoth-find-second-clovis-people-kill-site-found-in-new-mexico/109750">sites excavated in the western United States</a>, archaeologists know Paleo-American Clovis hunter-gatherers who lived around the time of the extinctions at least occasionally killed or scavenged ice age megafauna such as mammoths. There they’ve found preserved bones of megafauna together with the stone tools used for killing and butchering these animals. These sites are crucial for understanding the possible role that early Paleo-Americans played in the extinction event.</p>
<p>Unfortunately, many areas in the Southeastern United States lack sites with preserved bone and associated stone tools that might indicate whether megafauna were hunted there by Clovis or other Paleo-American cultures. Without evidence of preserved bones of megafauna, archaeologists have to find other ways to examine this question.</p>
<p>Forensic scientists have used an <a href="https://www.ojp.gov/ncjrs/virtual-library/abstracts/use-crossover-immunoelectrophoresis-detect-human-blood-protein-soil">immunological blood residue analysis</a> technique called <a href="https://doi.org/10.1016/0379-0738(78)90025-7">immunoelectrophoresis</a> for over 50 years to identify blood residue sticking to objects found at crime scenes. In recent years, researchers have applied this method to identify <a href="https://doi.org/10.1016/j.jasrep.2022.103785">animal blood proteins preserved within ancient stone tools</a>. They compare aspects of the ancient blood with blood antigens derived from modern relatives of extinct animals.</p>
<p>Residue analysis does not rely on the presence of nuclear DNA, but rather on preserved, identifiable proteins that sometimes survive <a href="https://doi.org/10.1006/jasc.2000.0628">within the microscopic fractures and flaws of stone tools</a> created during their manufacture and use. Typically, only a small percentage of artifacts produce <a href="https://library-archives.canada.ca/eng/services/services-libraries/theses/Pages/item.aspx?idNumber=27681369">positive blood residue results</a>, indicating a match between the ancient residue and antiserum molecules from modern animals.</p>
<p><a href="https://www.postandcourier.com/aikenstandard/news/a-lot-of-unknowns/article_95d93585-8455-5af6-b9e1-536b629f49ee.html">A previous blood residue study</a> of a small number of Paleo-American artifacts in South Carolina and Georgia failed to provide evidence that these people had hunted or scavenged extinct megafauna. The researchers found evidence of bison and other animals such as deer, bear and rabbit, but no evidence of Proboscidean (mammoth or mastodon) or of an extinct species of North American horse.</p>
<h2>Identifying ancient prey of human hunters</h2>
<p>My colleagues and I realized we needed a much larger sample of Paleo-American stone tools for testing. Since Clovis points and other Paleo-American artifacts are rare, I relied heavily on local museums, private collectors, collections housed at state universities and even military installations to amass a sample of 120 Paleo-American stone tools from all over North Carolina and South Carolina.</p>
<p>Because these artifacts are irreplaceable, I personally carried all 120 Clovis spearpoints and tools inside a protective case on a flight from South Carolina to the blood residue lab in Portland, Oregon. I coordinated in advance with the Transportation Security Administration so my collection of 13,000-year-old weaponry would make it through the screening process.</p>
<p>The blood residue analysis provided unambiguous proof that the tools had had contact with ancient animal blood proteins. The results included the first direct evidence on ancient stone tools of the blood of extinct mammoth or mastodon (Proboscidean) and the extinct North American horse (Equidae) on Paleo-American artifacts in eastern North America. This evidence is significant because it proves that these animals were present in the Carolinas, and they were hunted or scavenged by early Paleo-Americans.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/528323/original/file-20230525-23-9vbnei.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="artist's rendition of prehistoric people hitting a mastodon with spears" src="https://images.theconversation.com/files/528323/original/file-20230525-23-9vbnei.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/528323/original/file-20230525-23-9vbnei.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=417&fit=crop&dpr=1 600w, https://images.theconversation.com/files/528323/original/file-20230525-23-9vbnei.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=417&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/528323/original/file-20230525-23-9vbnei.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=417&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/528323/original/file-20230525-23-9vbnei.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=524&fit=crop&dpr=1 754w, https://images.theconversation.com/files/528323/original/file-20230525-23-9vbnei.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=524&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/528323/original/file-20230525-23-9vbnei.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=524&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">It likely would have taken a group of hunters to take down a mastodon.</span>
<span class="attribution"><a class="source" href="https://georgiainfo.galileo.usg.edu/gastudiesimages/Mastodon%20Hunt%201.htm">Ed Jackson</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>In addition to Proboscidean and horse, bison (Bovidae) blood residues were most common, adding to earlier blood residue research <a href="https://doi.org/10.7183/0002-7316.81.1.132">suggesting a focus on bison hunting</a> by Clovis and other Paleo-American cultures. Bison in North America did not go extinct but <a href="https://en.wikipedia.org/wiki/Bison_antiquus">instead became smaller</a>, most likely as a result of climate change as the last ice age ended and the climate warmed.</p>
<p>So, what do these results suggest for the extinction debate? While this study does not prove humans were responsible for the extinctions, it does show that early Paleo-Americans across the continent likely hunted or scavenged these animals, at least occasionally. The results also indicate that Proboscideans and horses were around when Clovis people were here – only a few hundred years before their eventual extinction in North America.</p>
<p>Another interesting finding is that while Proboscidean blood residues are found on Clovis artifacts, blood residues for horses (Equidae) are found on both Clovis and Paleo-American points that are slightly more recent younger than Clovis. This may suggest the extinction of Proboscidean was complete in the Carolinas by the end of the Clovis period, and the extinction of ice age horse species took longer.</p>
<p>Testing an even larger sample of Paleo-American stone tools from different regions of North America could help pin down the timing and geographic variability in the extinction of megafauna species and provide more clues about why these animals disappeared when they did.</p><img src="https://counter.theconversation.com/content/205556/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christopher R. Moore is affiliated with the the non-profit Comet Research Group (CRG).</span></em></p>
A forensic technique more often used at modern crime scenes identified blood residue from large extinct animals on spearpoints and stone tools used by people who lived in the Carolinas millennia ago.
Christopher R. Moore, Research Professor and Director of the Southeastern Paleoamerican Survey (SEPAS) at the South Carolina Institute for Archaeology and Anthropology, University of South Carolina
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/205544
2023-05-16T12:41:13Z
2023-05-16T12:41:13Z
Gay men can now donate blood after FDA changes decades-old rule – a health policy researcher explains the benefits
<figure><img src="https://images.theconversation.com/files/525731/original/file-20230511-941-a7vrz0.jpg?ixlib=rb-1.1.0&rect=0%2C20%2C6709%2C4446&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Allowing gay and bisexual men to donate blood would help alleviate chronic blood supply shortages in the U.S.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/donating-blood-royalty-free-image/1093904562?phrase=blood+donation&adppopup=true">Petri Oeschger/Moment via Getty Images</a></span></figcaption></figure><p><em>The U.S. Food and Drug Administration announced on May 11, 2023, that it has officially <a href="https://www.npr.org/2023/05/11/1175622785/fda-blood-donations-gay-bisexual-men">dropped restrictions that prohibit gay and bisexual men</a> from donating blood under many circumstances on May 11, 2023. The ban was <a href="https://doi.org/10.1111/1468-0009.12114">initially put in place</a> in the early days of the AIDS epidemic, but for years medical professionals and gay rights advocates have argued that the ban was no longer medically justifiable and that it unnecessarily discriminated against <a href="https://theconversation.com/men-who-have-sex-with-men-originated-during-the-hiv-pandemic-to-focus-on-behavior-rather-than-identity-but-not-everyone-thinks-the-term-helps-189619">men who have sex with men</a>.</em></p>
<p><em><a href="https://luskin.ucla.edu/person/ayako-miyashita-ochoa">Ayako Miyashita</a> is a health policy researcher at the University of California, Los Angeles, who studies HIV treatment and prevention. She explains the history of the ban and the reasoning behind its long-awaited reversal.</em></p>
<h2>1. When and why did the ban begin?</h2>
<p>When the FDA <a href="https://doi.org/10.1111/1468-0009.12114">first implemented the blood donation ban</a> in 1983 for men who have sex with men, there were good reasons for broad regulations to ensure the safety of the blood supply. At the start of the AIDS epidemic, public health officials were dealing with an unknown virus that was spread through unknown means. Researchers <a href="https://doi.org/10.1126/science.6200936">formally identified HIV as the cause of AIDS</a> a year later, in 1984, and it took another year to approve the first test to screen blood donations for HIV in 1985.</p>
<p>Despite the ban on blood donations from men who have sex with men, there was some small risk that failures in <a href="https://doi.org/10.1111/trf.14195">donor screening</a> and <a href="https://www.federalregister.gov/documents/2011/07/19/2011-18093/quarantine-release-errors-in-blood-establishments-public-workshop">blood screening protocols</a> could lead to transmission of HIV or other diseases from blood transfusion. But over the years, scientific advancements and strict protocols have helped to nearly <a href="https://doi.org/10.1111/trf.12423">eliminate HIV transmission</a> through blood. In fact, the last documented transmission of HIV through the a U.S. donor’s blood product <a href="https://www.cdc.gov/mmwr/preview/mmwrhtml/mm5941a3.htm">occurred nearly 15 years ago</a>.</p>
<p>Starting in 2013, the U.S. government began implementing a nationwide <a href="https://doi.org/10.1111/trf.13632">system to monitor</a> the safety of the U.S. blood supply for a variety of different pathogens, including HIV. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/526324/original/file-20230515-31713-uevzio.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A bag of donated blood." src="https://images.theconversation.com/files/526324/original/file-20230515-31713-uevzio.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/526324/original/file-20230515-31713-uevzio.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/526324/original/file-20230515-31713-uevzio.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/526324/original/file-20230515-31713-uevzio.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/526324/original/file-20230515-31713-uevzio.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/526324/original/file-20230515-31713-uevzio.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/526324/original/file-20230515-31713-uevzio.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Modern tests and screening protocols prevent blood of people with HIV or other diseases from getting into the U.S. blood supply.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/phlebotomist-adel-velasco-prepares-a-blood-donation-at-a-news-photo/1308846819?adppopup=true">MediaNews Group/Los Angeles Daily News via Getty Images</a></span>
</figcaption>
</figure>
<h2>2. Why lift the ban now?</h2>
<p>While the blood donation ban – as well as many other <a href="https://www.cdc.gov/hiv/policies/law/states/exposure.html">laws passed in the 1980s regarding HIV exposure and spread</a> – were reasonable at the time, the science has changed. Researchers and public health officials have gained a better understanding of how HIV is transmitted and the risks associated with different activities. Given today’s knowledge, many <a href="https://www.ama-assn.org/about/leadership/fda-must-lift-its-discriminatory-blood-donor-policy">medical experts believe</a> that the benefits of the ban no longer outweigh the hit to the blood supply or the harm caused by what is a discriminatory rule. </p>
<p>The FDA has been slowly working toward this change. In December 2015, the organization took a big step by allowing men who have sex with men to donate blood if they hadn’t had <a href="https://www.federalregister.gov/documents/2020/06/17/2020-13051/revised-recommendations-for-reducing-the-risk-of-human-immunodeficiency-virus-transmission-by-blood">sexual contact in one year</a>. That period was <a href="https://www.govinfo.gov/content/pkg/FR-2020-06-17/pdf/2020-13051.pdf">further reduced to three months</a> in April 2020, during the height of the COVID-19 pandemic, to help fight a <a href="https://www.redcross.org/about-us/news-and-events/press-release/2020/american-red-cross-faces-severe-blood-shortage-as-coronavirus-outbreak-threatens-availability-of-nations-supply.html">critical blood shortage</a>. </p>
<p>While a step in the right direction, these updates didn’t change the blunt assessment by the FDA that men who have sex with men are performing high-risk sexual behaviors and are themselves high-risk donors. Researchers and gay rights advocates have long argued that <a href="https://doi.org/10.1056/NEJMp2112329">time-based deferrals lack nuance</a> and fail to realistically consider the differences in risk associated with the type of sex, type of relationship, number of partners and frequency of sexual encounters.</p>
<p>The FDA’s latest <a href="https://www.fda.gov/regulatory-information/search-fda-guidance-documents/recommendations-evaluating-donor-eligibility-using-individual-risk-based-questions-reduce-risk-human">draft recommendations</a> go a long way toward improving clarity about what makes a person a high-risk donor and removes the blanket categorization of prospective donors based on their gender and sexual orientation alone.</p>
<p>Under the new guidelines, there is a way to differentiate between individuals who are monogamous and those who are not, as well as between those who have not engaged in anal sex in the prior three months and those who have. The recommendation now suggests that blood donor history questionnaires be used to evaluate an individual’s risk rather than a reliance on broad categorizations. If the assessment finds an individual to be high-risk, then the guidelines recommend that person be prevented from donating blood for three months.</p>
<h2>3. What effect could this have on the blood supply?</h2>
<p>The FDA’s latest move represents a seismic shift for men who have sex with men as well as for the <a href="https://theconversation.com/heading-into-the-third-year-of-the-pandemic-the-us-blood-supply-is-at-a-10-year-low-175906">critically low U.S. blood supply</a>. </p>
<p>According to recent research, a conservative estimate suggests that the lifting of the ban will lead to a <a href="https://williamsinstitute.law.ucla.edu/publications/blood-donation-ban-msm/">2% to 4% increase in the blood supply</a>. With the ongoing blood shortage, that increase could help save more than a million lives. In addition, removing gender and sexual orientation from the risk assessment for blood donation will take the U.S. one step further in addressing stigma and discrimination against men who have sex with men.</p><img src="https://counter.theconversation.com/content/205544/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ayako Miyashita does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
In 1983, during the early days of the AIDS epidemic, the US Food and Drug Administration made the decision to ban gay men from donating blood. Now, 40 years later, it is dropping that rule.
Ayako Miyashita, Adjunct Professor of Public Policy and Social Welfare, University of California, Los Angeles
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/201354
2023-03-23T17:33:36Z
2023-03-23T17:33:36Z
Why sitting with crossed legs could be bad for you
<figure><img src="https://images.theconversation.com/files/516946/original/file-20230322-427-il74jk.jpg?ixlib=rb-1.1.0&rect=22%2C8%2C2973%2C1980&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sitting with legs crossed for prolonged periods may have negative health effects, expert warns.</span> <span class="attribution"><a class="source" href="https://www.pexels.com/photo/a-man-using-a-laptop-8553844/">Polina Tankilevitch/Shutterstock</a></span></figcaption></figure><p>Are you sitting comfortably? Just pause for a moment and without adjusting, notice your posture. What are your legs doing? Are they crossed? And are you a right or left crosser? Some <a href="https://pubmed.ncbi.nlm.nih.gov/8084429/">62% of people</a> cross right over left, 26% go the other way and 12% have no preference. </p>
<p>There are typically two ways to sit in a chair and cross your legs, one is at the knee and the other is at the ankle. But as comfy as it may be to sit with your legs crossed, is it bad for your health and posture? Let’s take a look at the evidence.</p>
<p>For a start, research shows that sitting cross-legged can increase the <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7370107/">misalignment of the hips</a>, with one being higher than the other. </p>
<p>And it <a href="https://cdnsciencepub.com/doi/10.1139/apnm-2018-0339">changes the speed</a> at which blood moves through the blood vessels in the lower limbs, which can increase the risk of blood clots.</p>
<p>Most of the research suggests crossing at the knees is worse than the ankles. Indeed, sitting this way can cause an increase in your blood pressure due to the pooling of blood in the veins and your heart having to work against this. And this can increase the risk of damage to your blood vessels, which is why when you get your blood pressure taken you should have your <a href="https://www.tandfonline.com/doi/abs/10.1080/08037050410000903">feet flat on the floor</a>.</p>
<h2>Effect on the body</h2>
<p>The longer and more often you sit cross-legged, the more likely it is that you’ll have long-term changes in the muscle lengths and bone arrangements in your pelvis. And due to the way your skeleton is linked together, leg crossing can also cause misalignment of the spine and shoulders. </p>
<p>Your head position can potentially become out of alignment due to changes in the <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4905931/">bones of the neck</a>, as the spine compensates to keep your centre of gravity above the pelvis.</p>
<p>Your neck can also be affected due to one side of the body being weaker than the other. The same imbalance can be seen in the muscles of the pelvis and lower back as a result of poor posture and stresses and strains caused by sitting cross-legged.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/we-have-weaker-bones-than-our-hunter-gatherer-ancestors-this-is-what-you-can-do-about-it-105016">We have weaker bones than our hunter-gatherer ancestors – this is what you can do about it</a>
</strong>
</em>
</p>
<hr>
<p>The pelvis may also become misaligned due to the prolonged stretching of the gluteal (bum) muscles on one side, meaning that they become weaker.</p>
<p>Sitting with the legs crossed for a long time increases the likelihood of scoliosis (<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5140821/">abnormal alignment of the spine</a>) and other deformities. It can also cause <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5604828/">greater trochanteric pain syndrome</a>, a common and painful condition that affects the outer side of the hip and thigh.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/516950/original/file-20230322-1056-e3oozo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/516950/original/file-20230322-1056-e3oozo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/516950/original/file-20230322-1056-e3oozo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/516950/original/file-20230322-1056-e3oozo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/516950/original/file-20230322-1056-e3oozo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/516950/original/file-20230322-1056-e3oozo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/516950/original/file-20230322-1056-e3oozo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Say goodbye to leg-crossing.</span>
<span class="attribution"><a class="source" href="https://www.pexels.com/photo/a-dog-sitting-under-the-table-5990704/">Pexels/Cottonbro studio</a></span>
</figcaption>
</figure>
<p>Research also shows that sitting with legs crossed can put the peroneal nerve, also known as the fibular nerve, in your lower leg at risk of <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3730027/">compression and injury</a>. This typically manifests as a weakness when trying to lift the little-toe side of the foot as well as the more <a href="https://www.ncbi.nlm.nih.gov/books/NBK549859/">concerning foot drop</a> – where the whole of the foot <a href="https://www.bmj.com/content/350/bmj.h1736">hangs down</a>. Though in most cases, this is short-lived and returns to normal within a few minutes.</p>
<p>There’s also evidence that crossing the legs could affect sperm production. This is because the temperature of the testicles needs to be between <a href="https://www.tandfonline.com/doi/full/10.1080/19396368.2022.2074325">2°C and 6°C</a> below standard body temperature. Being seated increases the temperature of the testicles by 2°C and crossing your legs can increase the temperature of the testes by as much as <a href="https://onlinelibrary.wiley.com/doi/pdf/10.2164/jandrol.106.000646">3.5°C</a>. And <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4737001/">studies suggest</a> that an <a href="https://pubmed.ncbi.nlm.nih.gov/31841801/">increase in scrotum or testicle temperature</a> can reduce both sperm count and quality.</p>
<p>It’s also worth noting that due to differences in the <a href="https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.23552">anatomy</a> <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3407338/">of men and women</a> it’s probably much easier for women to sit cross-legged – particularly because men have a reduced <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5425325/">range of motion</a> at the hip.</p>
<h2>Legs and joints</h2>
<p>But research does indicate that sitting with legs crossed can be beneficial for some people. One small study from 2016, for example, found that for people who have <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8687568/">one leg longer than the other</a>, sitting crossed-legged can help to adjust the height of the two sides of the pelvis, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5140821/">improving alignment</a>. </p>
<p>Sitting with legs crossed also appears to <a href="https://pubmed.ncbi.nlm.nih.gov/8578373/">reduce the activity</a> of some muscles, particularly the oblique muscles (those beneath the skin where you put your hands on your hips) compared to sitting with legs forward. This may help relax your core muscles and prevent over-exertion. </p>
<figure class="align-center ">
<img alt="Woman sitting in meditation pose." src="https://images.theconversation.com/files/516953/original/file-20230322-1527-1ribfs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/516953/original/file-20230322-1527-1ribfs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/516953/original/file-20230322-1527-1ribfs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/516953/original/file-20230322-1527-1ribfs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/516953/original/file-20230322-1527-1ribfs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/516953/original/file-20230322-1527-1ribfs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/516953/original/file-20230322-1527-1ribfs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">But what about the lotus position?</span>
<span class="attribution"><a class="source" href="https://www.pexels.com/photo/photo-of-woman-doing-yoga-while-sitting-on-rock-3820380/">Pexels/Rfstudio</a></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/sitting-on-the-floor-vs-sitting-on-a-chair-which-is-better-for-you-141164">Sitting on the floor vs sitting on a chair – which is better for you?</a>
</strong>
</em>
</p>
<hr>
<p>Similarly, there is evidence that sitting cross-legged <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7370107/">improves</a> the stability of the sacroiliac joints (responsible for transferring weight between the spine and legs).</p>
<p>And of course, the famous yoga or meditation pose (lotus position) sees people sitting on the floor with legs crossed. Though there is limited data as to whether long periods of time spent in this position may lead to some of the issues that sitting cross-legged in a chair causes. Indeed, for many people <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6081169/">yoga offers huge benefits</a> – even those who already have knee issues.</p>
<p>So the verdict? It’s probably better to avoid crossing your legs if you can. Though that said, many of the risk factors associated with crossing your legs are likely exacerbated by other underlying issues such as <a href="https://theconversation.com/sitting-on-the-floor-vs-sitting-on-a-chair-which-is-better-for-you-141164">sedentary lifestyles</a> and obesity. So with this in mind, the main advice is to not sit still in the same position for too long and to keep regularly active.</p><img src="https://counter.theconversation.com/content/201354/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Adam Taylor does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
The science behind why crossing your legs while sitting could be detrimental to your health.
Adam Taylor, Professor and Director of the Clinical Anatomy Learning Centre, Lancaster University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/196016
2022-12-13T22:56:16Z
2022-12-13T22:56:16Z
Why does the Alzheimer’s brain become insulin-resistant?
<figure><img src="https://images.theconversation.com/files/499100/original/file-20221205-26-1etuem.jpg?ixlib=rb-1.1.0&rect=7%2C7%2C988%2C555&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Type 2 diabetes, characterised in its advanced stages by insulin resistance, is an important risk factor for Alzheimer's disease.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>As the population ages, the number of people with <a href="https://braininstitute.ca/research-data-sharing/neurodegenerative-disorders">neurodegenerative diseases</a>, such as <a href="https://alzheimer.ca/en/about-dementia/what-alzheimers-disease">Alzheimer’s disease</a>, increases. Approximately <a href="https://www.canada.ca/en/public-health/services/publications/diseases-conditions/dementia-highlights-canadian-chronic-disease-surveillance.html">75,000 Canadians</a> are diagnosed with Alzheimer’s disease each year and experience a decline in their cognitive abilities. The ordeal usually lasts for several years while their family members watch helplessly.</p>
<p>Neurodegenerative diseases are characterized by <a href="https://www.sciencedirect.com/science/article/abs/pii/S0924977X13001107">proteinopathies</a> — abnormal accumulations of proteins in the brain that impair the functioning of <a href="https://cancer.ca/en/cancer-information/resources/glossary/n/neuron">neurons</a>. The most widely studied therapeutic approach to developing drugs for Alzheimer’s is to try to reduce the aggregation of <a href="https://canjhealthtechnol.ca/index.php/cjht/article/view/eh0103/683">amyloid-beta peptide</a> and <a href="https://nouvelles.umontreal.ca/en/article/2022/10/20/unlocking-the-mysteries-of-tauopathies-a-protein-that-gives-hope/">tau protein</a> in neurons.</p>
<p>However, in order to reach their targets, the drugs must first cross the <a href="https://www.theglobeandmail.com/canada/article-toronto-researchers-look-at-new-approach-for-treating-alzheimers/">blood-brain barrier</a> (BBB) from the blood to the brain. This is because <a href="https://www.biorxiv.org/content/10.1101/2020.12.10.419598v1.full">endothelial cells</a>, cells that line the tiniest blood vessels in the brain, regulate the exchange between blood and the brain. They maintain a balance that allows access to essential molecules such as glucose, but restrict the passage of <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3494002/">most pharmaceuticals</a>, including the new and <a href="https://www.ft.com/content/32478dbf-7270-4eb6-a576-663a47a3603e">much-hyped</a> drug <a href="https://www.nejm.org/doi/full/10.1056/NEJMoa2212948">lecanemab</a>.</p>
<p>When these brain endothelial cells become diseased, the balance is upset. The brain struggles to get the substances it needs back into the circulation and rejects those that might harm it.</p>
<p>The brain and the other organs of the body are thus in constant communication, while in health or in disease.</p>
<p>As experts in neurodegenerative diseases and the BBB, we have conducted a study on insulin receptor dysfunction in Alzheimer’s disease.</p>
<h2>Insulin and the brain</h2>
<p><a href="https://www.healthlinkbc.ca/health-topics/types-insulin">Insulin</a> is an essential hormone for life. It is best known for its effect on the regulation of <a href="https://www.diabetescarecommunity.ca/living-well-with-diabetes-articles/blood-sugar-levels-in-canada/?gclid=Cj0KCQiAyracBhDoARIsACGFcS4fee8N8dfBJj9HKxpUiGlNO6RANNF9BiZN52dsd6oxqgLCW7Od_WsaArF9EALw_wcB">blood sugar</a> and remains an essential part of the pharmaceutical treatment of <a href="https://www.healthlinkbc.ca/health-topics/types-insulin">diabetes</a>. In recent decades, researchers have noted vascular and metabolic abnormalities <a href="https://pubmed.ncbi.nlm.nih.gov/30022099/">in a high proportion of patients with dementia</a>.</p>
<p>Indeed, Type 2 diabetes, characterized in the later stages by <a href="http://www.diabetesclinic.ca/en/diab/1basics/insulin_resistance.htm">insulin resistance</a>, is a major risk factor for Alzheimer’s disease. There is some evidence to suggest that the <a href="https://pubmed.ncbi.nlm.nih.gov/29377010/">Alzheimer’s brain is less responsive to insulin</a>. Conversely, studies have shown that insulin can <a href="https://pubmed.ncbi.nlm.nih.gov/32730766/">improve memory</a>, prompting the development of clinical trials on the effect of insulin on Alzheimer’s disease.</p>
<p>Yet we still don’t know what cell types and mechanisms are involved in the action — and loss of action — of insulin in the brain. The vast majority of insulin is produced by the <a href="https://pancreaticcancercanada.ca/the-pancreas/">pancreas</a> and secreted into the bloodstream. Therefore, to affect the brain, insulin must first interact with the BBB and its endothelial cells, which are in contact with the blood and can take up insulin through <a href="https://pubmed.ncbi.nlm.nih.gov/36280236/">receptors</a>.</p>
<h2>Alzheimer’s and the insulin receptor</h2>
<p>In order to measure the amount of these insulin receptors in the brain, <a href="https://doi.org/10.1093/brain/awac309">we performed analyses directly in human tissues</a>. These samples came from a <a href="https://www.rushu.rush.edu/research/departmental-research/religious-orders-study">cohort</a> of over a thousand people who agreed to donate their brains after death. We have access to them through a partnership with researchers at Rush University in Chicago.</p>
<p>We found that the <a href="https://healthenews.mcgill.ca/new-insights-into-how-insulin-interacts-with-its-receptor/">insulin-binding receptor</a> is predominantly located in the microvessels, so, within the BBB itself. Moreover, the abundance of this receptor is decreased in Alzheimer’s patients. This decrease could lead to the loss of insulin response in the Alzheimer brain.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/499093/original/file-20221205-15238-9izujo.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="schematic" src="https://images.theconversation.com/files/499093/original/file-20221205-15238-9izujo.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/499093/original/file-20221205-15238-9izujo.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=781&fit=crop&dpr=1 600w, https://images.theconversation.com/files/499093/original/file-20221205-15238-9izujo.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=781&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/499093/original/file-20221205-15238-9izujo.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=781&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/499093/original/file-20221205-15238-9izujo.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=982&fit=crop&dpr=1 754w, https://images.theconversation.com/files/499093/original/file-20221205-15238-9izujo.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=982&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/499093/original/file-20221205-15238-9izujo.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=982&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The brain insulin receptor is located mainly at the BBB, and its ability to respond to blood insulin is diminished in Alzheimer’s disease.</span>
<span class="attribution"><span class="source">(Manon Leclerc)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Insulin receptor dysfunction</h2>
<p>In order to better control the experimental variables and measure the response of the insulin receptor, we then tested our hypotheses in mice. The <em>in situ</em> cerebral perfusion technique consists of injecting insulin directly into the carotid artery (an artery located in the neck) so that it reaches the brain in its entirety. We have shown that circulating insulin mainly activates receptors located on the cerebral microvessels.</p>
<p>Although it was generally accepted that insulin crosses the BBB to reach cells such as neurons deeper in the brain tissue, our results show that the proportion of insulin that crosses the BBB is low.</p>
<p>These two observations thus confirm that the majority of insulin must interact with cells in the BBB before it can exert an action on the brain.</p>
<p>We then applied the same method to <a href="https://www.criver.com/products-services/research-models-services/genetically-engineered-model-services/transgenic-mouse-rat-model-creation/transgenic-mice?region=3601">transgenic mice</a>, which were genetically modified to model Alzheimer’s disease. We found that the response to insulin at the BBB was dysfunctional, with no activation of the insulin receptor in these diseased mice.</p>
<p>Thus, in both humans and rodents, the brain insulin receptor is located primarily at the BBB, and its ability to respond to blood insulin is impaired in Alzheimer’s disease.</p>
<h2>A significant breakthrough</h2>
<p>In sum, our results suggest that alterations in the number, structure and function of insulin receptors at the level of BBB endothelial cells may contribute to the cerebral insulin resistance observed in Alzheimer’s disease.</p>
<p>Alzheimer’s research efforts are currently focused on drugs that, in order to reach their therapeutic target, the neurons, must first cross the BBB, which severely restricts their passage. By targeting the metabolic dysfunction of the brain instead, we propose a research alternative that has two major advantages.</p>
<p>The first is that we can use treatments that do not have to cross the BBB barrier, since it is the endothelial cells themselves that become the therapeutic target. The second involves <a href="https://www.nature.com/articles/nrd.2018.168">“drug repurposing,”</a> which consists of taking advantage of the phenomenal therapeutic arsenal already approved to fight diabetes and obesity, but using this in the context of Alzheimer’s.</p>
<p>It should be remembered that the few drugs available to us provide only a modest improvement in symptoms. Combating insulin resistance in the brain would make it possible to break the vicious circle between neuropathology (disease that affects the brain) and diabetes, and in theory slow down the progression of the disease.</p>
<h2>The work is not finished</h2>
<p>On the basic research side, we will continue to study the mechanisms downstream from the microvessels to understand the action of insulin on the deep layers of the brain.</p>
<p>We hope that clinical research will follow suit with human studies to repurpose drugs that target certain metabolic diseases, such as diabetes, towards fighting Alzheimer’s.</p>
<p>In the meantime, while waiting for pharmaceutical solutions, each of us would do well to adopt the preventive cocktail that we all know well: a healthy diet combined with frequent physical and mental exercise.</p><img src="https://counter.theconversation.com/content/196016/count.gif" alt="La Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Frederic Calon has received funding from: Canadian Institutes of Health Research (CIHR), Natural Sciences and Engineering Research Council of Canada (NSERC), Fonds de la recherche du Québec en santé (FRQS), Alzheimer Society of Canada.</span></em></p><p class="fine-print"><em><span>Manon Leclerc has received scholarships from the Fondation du CHU de Québec and the Fonds de Recherche du Québec - Santé (FRQS).</span></em></p><p class="fine-print"><em><span>Vincent Emond ne travaille pas, ne conseille pas, ne possède pas de parts, ne reçoit pas de fonds d'une organisation qui pourrait tirer profit de cet article, et n'a déclaré aucune autre affiliation que son organisme de recherche.</span></em></p>
Impaired insulin receptors in the blood vessels between the blood and the brain may contribute to the insulin resistance observed in Alzheimer’s disease.
Frederic Calon, Professeur, Université Laval
Manon Leclerc, PhD student, Université Laval
Vincent Emond, Professionnel de recherche, Université Laval
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/194207
2022-12-12T14:15:37Z
2022-12-12T14:15:37Z
Lab-grown blood used in transfusion for first time – here are three other ways that making organs could change healthcare
<figure><img src="https://images.theconversation.com/files/500027/original/file-20221209-24-lf5dp9.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5000%2C3742&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The red blood cells were made by extracting stem cells from a blood sample.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/3d-rendering-red-blood-cells-vein-516112096">Phonlamai Photo/ Shutterstock</a></span></figcaption></figure><p>Human volunteers have received the first-ever transfusion of <a href="https://www.nhsbt.nhs.uk/news/first-ever-clinical-trial-of-laboratory-grown-red-blood-cells-being-transfused-into-another-person/">lab grown red blood cells</a> in a groundbreaking scientific first. Volunteers received about 5ml-10ml of blood (around 1-2 teaspoons), which contained around 15 billion red blood cells. So far, volunteers who received the lab-grown blood cells are reported to be in good health. </p>
<p>To grow these red blood cells, researchers first extracted stem cells from a blood sample. They then directed these stem cells to grow into red blood cells in the laboratory. It’s hoped that these lab-grown blood cells may be used in the treatment of disorders that affect red blood cells – such as <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6142434/">sickle cell anaemia</a> and <a href="https://www.nhs.uk/conditions/thalassaemia/treatment/">thalassemia</a>.</p>
<p>While this is the first time blood has ever been grown in the lab, it certainly isn’t the first lab-grown innovation. Scientists have used laboratory-based models for years to investigate everything from organ and tissue function, to understand disease processes and to test new treatments. </p>
<p>Here are some of the other most promising lab-grown innovations to date. </p>
<h2>Organoids</h2>
<p>In recent years organoids, derived from various types of <a href="https://www.nature.com/articles/s41580-020-0259-3">stem cells</a>, have become more common in research. Organoids closely match the structure and function of full-size human organs. This allows researchers to study how many different diseases or viruses may affect human health. They also allow researchers to better understand stem cells (which they grown from), which can become almost any cell in the body. </p>
<p>For instance, organoid brains have helped scientists understand the devastating effect of <a href="https://www.science.org/content/article/zika-virus-kills-developing-brain-cells">Zika virus</a> on brain development. They’re also playing a wider key role in understanding different <a href="https://www.nature.com/articles/s41593-021-00923-4">neurological conditions</a>, such as <a href="https://www.ninds.nih.gov/amyotrophic-lateral-sclerosis-als-fact-sheet">ALS</a>. Organoid brains are extremely advantageous because they allow researchers to observe, in real-time, any changes that may occur in the brain as they happen – something not possible with humans. This will help us better know when and how to treat certain diseases.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/lab-grown-brain-cells-can-play-pong-so-should-they-have-legal-rights-192549">Lab-grown brain cells can play Pong – so should they have legal rights?</a>
</strong>
</em>
</p>
<hr>
<p><a href="https://www.science.org/content/article/lab-grown-minihearts-beat-real-thing">Organoid hearts</a> have also been successfully grown in the lab. After a week of development, they’re functionally equivalent to the heart of a 25-day-old embryo, able to beat between 60-100 times per minute. Recent advances have also enabled <a href="https://elifesciences.org/articles/69028">heart cells</a> to be grown from stem cells, paving the way to be able to grow larger and more efficient cardiac organs.</p>
<p>The cells from these organoids have also been shown to improve the performance of <a href="https://link.springer.com/article/10.1007/s00018-012-1078-2">damaged heart muscle</a> when given to animals. Similar work shows that they are also providing <a href="https://stemcellres.biomedcentral.com/articles/10.1186/s13287-021-02340-7">valuable information</a> in what happens in heart attack, heart failure and a number of genetic heart conditions. </p>
<figure class="align-center ">
<img alt="A stem cell researcher in a lab coat and mask looks through a microscope." src="https://images.theconversation.com/files/500029/original/file-20221209-33096-p9c7zt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/500029/original/file-20221209-33096-p9c7zt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/500029/original/file-20221209-33096-p9c7zt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/500029/original/file-20221209-33096-p9c7zt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/500029/original/file-20221209-33096-p9c7zt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/500029/original/file-20221209-33096-p9c7zt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/500029/original/file-20221209-33096-p9c7zt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Lab-grown organoids are made using stem cells.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/stem-cell-researcher-working-laboratory-1126848905">Microgen/ Shutterstock</a></span>
</figcaption>
</figure>
<p><a href="https://elifesciences.org/articles/66417">Organoid lungs</a> are also proving useful in understanding COVID-19 and testing new therapies, alongside helping scientists <a href="https://www.frontiersin.org/articles/10.3389/fcell.2022.899368/full">understand other diseases</a>, such as chronic obstructive pulmonary disease, asthma and certain types of pulmonary fibrosis. These kind of human lung organoids take approximately <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6531049/">eight weeks</a> to grow in the lab.</p>
<h2>Fully-grown organs</h2>
<p>Scientists have also been able to successfully grow fully-functioning organs in the lab.</p>
<p>For example, a small number of people are actually walking around with <a href="https://www.bbc.co.uk/news/business-45470799">fully-grown, functioning bladders</a> made from their own cells. These are produced in a lab by growing the <a href="https://academic.oup.com/bmb/article/97/1/81/360794#5208779">patient’s own bladder cells</a> and then 3D-printing them into the correct shape. It’s then surgically implanted into the patient. This process takes around two months to complete. But since these are grown from the patient’s own cells, it removes the risk of the body rejecting the new organ.</p>
<p>Lab-grown vaginas are another example. These are usually grown and implanted into women who are born without a vagina – such as those suffering from a rare disease called <a href="https://rarediseases.org/rare-diseases/mayer-rokitansky-kuster-hauser-syndrome/">Mayer-Rokitansky-Küster-Hauser Syndrome</a>. The process is somewhat similar as with bladders, whereby cells from their external genitalia are used to grow the vagina in a bio-reactor. </p>
<p>One of the biggest challenges that researchers now face is developing lab-grown skin. Skin is the largest organ in the body and is composed of three distinct layers. But finding a way of integrating these layers in the same way as they are in the body is proving difficult for scientists. </p>
<p>While skin cells have been successfully grown in labs for many years, it still takes between <a href="https://www.nature.com/articles/eye198831.pdf?origin=ppub">2-3 weeks</a> to grow enough skin cells to fill the area they’re being grafted onto. However, co-culturing them with cells from the underlying dermis (one of the skin’s three layers) has shown to <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3217074/">improve yield and performance</a> of lab-grown skin cells. Another challenge researchers face is growing skin which contains elements such as <a href="https://onlinelibrary.wiley.com/doi/full/10.1002/adhm.202201626">sweat glands and hairs</a>. These are essential as they help the skin perform one of its many important functions: regulating body temperature. </p>
<h2>Ears</h2>
<p>Scientists have successfully grown and 3D-printed <a href="https://www.independent.co.uk/news/science/children-new-ears-grown-own-cells-china-scientists-worlds-first-operation-transplant-a8187776.html">a human ear</a> using a patient’s cartilage cells. </p>
<p>It’s hoped that this development will help in treating people born with <a href="https://www.cdc.gov/ncbddd/birthdefects/anotia-microtia.html">microtia or anotia</a> – a birth defect that causes the ear not to form properly, or not form at all. The condition effects approximately one in every 2,000-10,000 births. But while the external ear improves appearance, there’s still the challenge of overcoming hearing loss due to the initial absence of the ear, which can also impact speech. </p>
<p>Almost <a href="https://www.organdonation.nhs.uk/helping-you-to-decide/about-organ-donation/statistics-about-organ-donation/">6,800 people</a> are waiting for an organ transplant in the UK and more than <a href="https://www.aier.org/article/the-organ-shortage/">15 times</a> that in the US. Advances in lab grown organs may provide an alternative for those waiting for transplants, and can be produced from a patient’s own cells. </p>
<p>Future innovations are looking towards other lab grown organs such as <a href="https://www.nature.com/articles/s41467-022-28226-7">kidneys</a> and <a href="https://www.nihr.ac.uk/news/human-liver-repaired-using-cells-grown-in-a-laboratory-for-the-first-time/27016">livers</a>, as these represent a large portion of the organs that people waiting for transplants need.</p><img src="https://counter.theconversation.com/content/194207/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Adam Taylor is affiliated with the Anatomical Society. </span></em></p>
Lab-grown technologies may help change the way certain human diseases are studied and treated.
Adam Taylor, Professor and Director of the Clinical Anatomy Learning Centre, Lancaster University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/191987
2022-11-08T16:48:53Z
2022-11-08T16:48:53Z
Blood groups: there are way more than you think – here’s why they matter
<figure><img src="https://images.theconversation.com/files/490359/original/file-20221018-7218-yoxe8v.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4382%2C2899&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/blood-transfusion-icu-1270878085">Kiryl Lis/Shutterstock</a></span></figcaption></figure><p>You are probably aware of the two main blood group systems: the AB system and the rhesus system. Under the AB system, there are four main blood types A, B, AB and O. And each of these four types can be “rhesus positive” or “rhesus negative”. It may surprise you to hear, though, that there are many more blood group systems than just these two. Indeed, researchers at the University of Bristol recently completed the <a href="https://www.bristol.ac.uk/news/2022/september/er-blood.html">44th blood group system</a> called Er.</p>
<p>Blood comprises white blood cells, plasma, platelets and red blood cells. It is the red blood cells that define these classification systems. </p>
<p>Although healthy red blood cells all appear the same down the microscope, close-up inspection shows they have crucial differences in the form of “antigens” – proteins and sugars that coat the red blood cells’ surfaces. It is these antigens that determine which blood group a person belongs to.</p>
<p>Most people go through life not really thinking about their blood group, but there are two stages in life when blood groups are fundamentally important: during pregnancy and when a blood transfusion is needed. </p>
<p>The <a href="https://www.nhs.uk/conditions/blood-groups/">ABO blood groups</a> are the most widely recognised. Austrian physician and biologist Karl Landsteiner discovered them in 1900. He noticed that when he mixed blood from different people in his lab, it sometimes <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3595629/">tended to clump</a>. </p>
<p>Landsteiner found three blood group types, which he named A, B and O (for the <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3595629/">German <em>ohne</em>, meaning without or null, because it didn’t clump at all</a>). Researchers at Landsteiner’s lab later discovered a fourth blood group: AB. </p>
<p>Today, we know the reason people with, say, blood group A can’t donate blood to people with blood group B is because of antigens. Someone with A has the A antigen on their red blood cell surface and antibodies in their plasma that attack B red blood cells, which are seen as invaders. (Antibodies are Y-shaped proteins that neutralise things that don’t belong in the body, such as harmful bacteria and viruses.) </p>
<p>The reason Landsteiner noticed that O blood never clumped is because it has no antigens on the red blood cells, so antibodies have no reason to attack it. This blood group remains the most important when it comes to transfusion. People with AB can receive blood from any other group (their plasma has no anti-A, anti-B antibodies). People with O can donate to any other group and are hence known as “universal donors”. It is also, fortunately, the most common blood type – about <a href="https://www.nhs.uk/conditions/blood-groups/">48% of people in the UK</a> have it.</p>
<p>Giving people the wrong blood used to cause a significant number of deaths. However, since our understanding of blood and blood groups has increased, this number has <a href="https://pubmed.ncbi.nlm.nih.gov/33064880/">declined</a> substantially.</p>
<h2>Many other blood groups besides</h2>
<p>After the ABO grouping, the next most commonly recognised group is rhesus. It relates to the presence of another protein on the surface of red blood cells and is also one of the most complex blood groups. People are either positive or negative. Being rhesus (Rh) positive is more common than negative, with <a href="https://www.nhs.uk/conditions/rhesus-disease/causes/">85% of the UK population</a> being Rh positive.</p>
<p>Rh status can cause significant risk in pregnancy, particularly during labour, when there is potential for maternal and foetal blood to mix. Mixing of blood can cause <a href="https://www.nhs.uk/conditions/rhesus-disease/">rhesus disease</a>, where the mother has Rh-negative blood and the baby has Rh-positive blood. This leads to the mother making antibodies to the baby’s Rh-positive blood cells. (Blood type is inherited. A woman with Rh-negative blood can have an Rh-positive baby if her partner’s blood type is Rh positive.)</p>
<p>While this is not usually an issue in the first pregnancy, it poses a greater risk to subsequent pregnancies where the foetus is Rh positive, as the mother retains a low level of circulating Rh antibodies. In any subsequent pregnancy, there is a risk to a Rh-positive foetus that these maternal antibodies will cross the placenta and begin to destroy the foetus’s red blood cells.</p>
<p>When these different blood groups go undetected, it can cause an immune reaction that has the potential to kill the foetus. This was the case in the most recent discovery of the 44th blood group (specifically, two new antigen variations called Er4 and Er5), where the baby suffered a haemorrhage and sadly passed away. It can take as little as <a href="https://www.ncbi.nlm.nih.gov/books/NBK430876/">0.01ml of blood</a> to mix between the foetus and mother to cause death. </p>
<p>Thankfully, there are treatments available, such as intrauterine blood transfusions for the foetus, that can stop this from happening.</p>
<p>The next group, which is one of the most complex blood groups, is the <a href="https://www.ncbi.nlm.nih.gov/books/NBK2270/">Kell</a> group. It was discovered in 1946 and named after “Mrs Kellacher”. This mother expressed anti-K(ell) antibodies to her K-positive foetus. In Kell haemolytic disease, the precursor cells to red blood cells are destroyed, causing extreme and sometimes fatal anaemia in the foetus.</p>
<p>There are many other blood groups, too, including Duffy, MNS, Lutheran, Kidd, P and Lewis systems, which, like those described above, have the potential to trigger an immune reaction, particularly between mother and foetus. </p>
<p>These are some of the more common blood groups that are recognised and need to be considered when planning for any type of blood transfusion to minimise the risk of <a href="https://bestpractice.bmj.com/topics/en-gb/1048">reaction</a>. Thankfully, there are protocols in place to ensure that blood is suitably matched and checked before being given to minimise any risks.</p>
<p>The rarer your blood group, though, the harder it can be to get blood for a transfusion, should you need one. Spare a thought for those people who are described as having “<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6305262/">golden blood</a>”. It is so rare that fewer than 50 people in the world are thought to possess it.</p><img src="https://counter.theconversation.com/content/191987/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Adam Taylor is affiliated with the Anatomical Society. </span></em></p>
A 44th blood group was recently discovered by researchers at Bristol University.
Adam Taylor, Professor and Director of the Clinical Anatomy Learning Centre, Lancaster University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/192746
2022-10-23T12:30:32Z
2022-10-23T12:30:32Z
Paying for plasma is the new normal: Why policy has changed decades after Canada’s tainted blood scandal
<figure><img src="https://images.theconversation.com/files/491135/original/file-20221021-20-u4i9xy.JPG?ixlib=rb-1.1.0&rect=102%2C54%2C4449%2C2756&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Blood plasma and products made from it are used to treat conditions ranging from blood clotting disorders to immunodeficiencies to Rh-negative pregnancies.</span> <span class="attribution"><span class="source">THE CANADIAN PRESS/AP-Arnulfo Franco</span></span></figcaption></figure><iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/paying-for-plasma-is-the-new-normal--why-policy-has-changed-decades-after-canada-s-tainted-blood-scandal" width="100%" height="400"></iframe>
<p>There has been a monumental policy shift in paying plasma donors in Canada.</p>
<p>In September, <a href="https://www.blood.ca/en/about-us/publications-and-reports/annual-reports">Canadian Blood Services</a> (CBS) made a <a href="https://www.grifols.com/en/view-news/-/news/grifols-enters-into-agreement-with-canadian-blood-services-to-accelerate-self-sufficiency-in-immunoglobulins-for-canada">15-year deal</a> with Spanish health-care giant Grifols for blood plasma collection and products. The deal upends the 1997 recommendations from the <a href="https://publications.gc.ca/site/eng/9.698032/publication.html?wbdisable=true">commission of inquiry into the tainted blood scandal</a> that urged no paid donations of blood or blood products.</p>
<p>More than 30,000 Canadians were infected with hepatitis C and another 2,000 contracted HIV from tainted blood and blood products during the ‘70s and ‘80s, resulting in more than <a href="https://www.thecanadianencyclopedia.ca/en/article/krever-inquiry">8,000 deaths</a>. </p>
<p>“The hemophilia community was decimated by HIV and hepatitis C through tainted blood,” David Page, national director of health policy at the <a href="https://www.chscontact.ca/">Canadian Hemophilia Society</a>, said at a <a href="https://sencanada.ca/en/Content/Sen/Committee/421/SOCI/53ev-54542-e">2019 Senate hearing</a>. </p>
<p>The <a href="https://publications.gc.ca/site/eng/9.698032/publication.html?wbdisable=true">Commission of Inquiry on the Blood System in Canada</a> released its final report in 1997. The recommendations were clear: do not pay blood donors, including those who donate plasma, “except in rare circumstances.” </p>
<h2>Policy shift</h2>
<p>Fast forward almost three decades and paying plasma donors is standard practice for <a href="https://giveplasma.ca/donors/compensation/">private plasma collection sites</a>. It’s supported by CBS (although it does not pay donors directly at its own sites), Health Canada and many of the groups most adversely affected by the tainted blood scandal, including <a href="https://chscontact.ca/chs-strongly-supports-cbs-plasma-initiative/">hemophiliacs</a> and those with <a href="http://www.cipo.ca/2022/08/15/update-on-canadian-blood-services-news/">primary immunodeficiency disorders</a> whose lives rely on plasma products.</p>
<figure class="align-center ">
<img alt="A window with the logo of Canadian Blood Services" src="https://images.theconversation.com/files/491136/original/file-20221021-3368-m4mvdw.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/491136/original/file-20221021-3368-m4mvdw.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/491136/original/file-20221021-3368-m4mvdw.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/491136/original/file-20221021-3368-m4mvdw.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/491136/original/file-20221021-3368-m4mvdw.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/491136/original/file-20221021-3368-m4mvdw.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/491136/original/file-20221021-3368-m4mvdw.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">In September, Canadian Blood Services made a deal with Spanish-based health-care giant Grifols for blood plasma collection and products.</span>
<span class="attribution"><span class="source">THE CANADIAN PRESS/Jeff McIntosh</span></span>
</figcaption>
</figure>
<p>Paid plasma donors can donate up to twice per week and can earn in excess of $500 per month by donating at the maximum frequency and volume of plasma collected, according to <a href="https://giveplasma.ca/donors/compensation/">Canadian Plasma Resources</a>, a company with plasma collection centres in the <a href="https://giveplasma.ca">Prairie provinces as well as New Brunswick</a>. </p>
<p>What caused this policy shift? Essentially: enhanced donor screening, rigorous regulation by both <a href="https://www.canada.ca/en/health-canada/services/drugs-health-products/biologics-radiopharmaceuticals-genetic-therapies/activities/fact-sheets/plasma-donation-canada.html">Health Canada</a> and the U.S. Food and Drug Administration, viral inactivation by heat or solvent processes and synthetic methods to produce some plasma products, namely clotting factors. </p>
<p>Page’s opinion has changed. In an interview, he said he feels that sufficient measures have been put in place to make plasma products safe, and supports using plasma from paid donors as a necessity to meet the health-care needs of Canadians. </p>
<p>In the quarter of a century since the tainted blood scandal there has not been a single case of disease transmission via a blood product in Canada, Page pointed out. He attributed this to enhanced regulatory and safety measures. </p>
<h2>Canada’s plasma supply</h2>
<p>The change in policy reflects a little-recognized truth about Canada’s blood system: It doesn’t come close to meeting the nation’s need.</p>
<p>In 2017 Health Canada established an expert <a href="https://www.canada.ca/en/health-canada/programs/expert-panel-immune-globulin-product-supply-related-impacts-canada/protecting-access-immune-globulins-canadians.html">panel on Immune Globulin Product Supply and Related Impacts</a>. It reported that more than 80 per cent of fractionated plasma products, namely immunoglobulins, comes from imported product, almost all from paid donors in the United States. It has cost CBS more than <a href="https://www.blood.ca/en/about-us/publications-and-reports/annual-reports">$700 million</a> a year. </p>
<p>CBS has set an objective of reducing dependence on imports of plasma-derived immunoglobulins to at least 50 per cent, and must do so “with a degree of urgency” <a href="https://drive.google.com/file/d/1_H5PI2JZFqmD_VP7z1ESDrO5AZmAa0sO/view">says Graham Sher</a>, CEO of CBS. </p>
<p>The new <a href="https://www.grifols.com/en/view-news/-/news/grifols-enters-into-agreement-with-canadian-blood-services-to-accelerate-self-sufficiency-in-immunoglobulins-for-canada">deal with Grifols</a> will provide 2.4 million grams of plasma-derived immunoglobulins, collected from Canadian donors, helping CBS reach its targets. </p>
<p>The company entered the Canadian market in 2011 and has a plasma fractionation plant in Montréal and a plasma collection site in Winnipeg. In addition, Grifols plans to expand paid plasma donor sites in Ontario and British Columbia as agents of CBS. </p>
<p>Neither side will reveal the contract details.</p>
<p>The deal with Grifols, by itself, will not meet CBS’s 50-per-cent target. To make up the difference <a href="https://www.blood.ca/en/about-us/media/newsroom/securing-canadas-plasma-supply">CBS plans</a> to increase its own dedicated plasma collection sites from five to 11 by 2024. CBS’s own plasma donation sites will remain uncompensated. </p>
<h2>Plasma and plasma products</h2>
<figure class="align-center ">
<img alt="Gloved hands holding up an IV bag filled with yellow fluid" src="https://images.theconversation.com/files/491134/original/file-20221021-13-d4alyq.jpg?ixlib=rb-1.1.0&rect=154%2C32%2C5280%2C3837&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/491134/original/file-20221021-13-d4alyq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=428&fit=crop&dpr=1 600w, https://images.theconversation.com/files/491134/original/file-20221021-13-d4alyq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=428&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/491134/original/file-20221021-13-d4alyq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=428&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/491134/original/file-20221021-13-d4alyq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=538&fit=crop&dpr=1 754w, https://images.theconversation.com/files/491134/original/file-20221021-13-d4alyq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=538&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/491134/original/file-20221021-13-d4alyq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=538&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Plasma donation can take up to two hours, significantly longer than donating whole blood.</span>
<span class="attribution"><span class="source">(AP Photo/Juan Karita)</span></span>
</figcaption>
</figure>
<p>Plasma differs from the whole blood that is collected for transfusion at donor clinics across the country. </p>
<p>During plasma collection, red and white blood cells and platelets are returned to the donor, leaving a straw-coloured liquid called plasma. This process is called <a href="https://www.canada.ca/en/health-canada/services/drugs-health-products/biologics-radiopharmaceuticals-genetic-therapies/activities/fact-sheets/plasma-donation-canada.html">plasmapheresis</a>. </p>
<p>Essential proteins, such as albumin, clotting factors and immunoglobulins, are recovered from the plasma through <a href="https://www.blood.ca/en/about-us/media/newsroom/plasma-and-blood-system-supply-chain">fractionation</a>.</p>
<p>Such plasma is called “source plasma” and is used only after it has been treated to remove or inactivate viruses and other pathogens. CBS cannot supply sufficient source plasma products, namely immunoglobulins, from unpaid donors, to meet the needs of Canadians and has been buying fractionated plasma products since its inception in 1998. It spent more than $200 million on plasma in 2000 and within the last five years has spent more than <a href="https://annual2019.blood.ca/?_ga=2.139020853.760828163.1666374799-375334784.1662912652&_gl=1*1ba3sb6*_ga*Mzc1MzM0Nzg0LjE2NjI5MTI2NTI.*_ga_YHMRKTXXVD*MTY2NjM3NDc5OS44LjEuMTY2NjM3NTEzNy4wLjAuMA">$700 million per year</a>. </p>
<p>For patients with <a href="https://www.canada.ca/en/health-canada/programs/expert-panel-immune-globulin-product-supply-related-impacts-canada/protecting-access-immune-globulins-canadians.html">immunodeficiencies, those requiring protection from diseases such as rabies or tetanus or Rh-negative pregnant patients</a>, there are no other treatment options. </p>
<h2>Opposition</h2>
<p>Meanwhile, there is still opposition to paying plasma donors. <a href="https://bloodwatch.org/">BloodWatch</a>, a not-for-profit organization, opposes paying donors for plasma or other human tissues. It is a strong proponent of a fully public blood collection system, as is the <a href="https://www.healthcoalition.ca/">Canadian Health Coalition</a>. </p>
<p>BloodWatch cites safety, profit making and potential exploitation of plasma donors as reasons to reject the Grifols deal. A hybrid system of paid and unpaid donors competes with, and compromises, Canada’s ability to become self-sufficient, it argues.</p>
<p>The Canadian Hemophilia Society’s Page disagrees.</p>
<p>“We generally do not make drugs with our public health-care system,” he says, likening fractionated plasma products to drugs. Not least, he adds, plasma collection takes up to two hours, more than twice as long as conventional blood donation. </p>
<p><em>Dr. Sandor Demeter is Fellow of the Dalla Lana Fellowship in Global Journalism</em></p><img src="https://counter.theconversation.com/content/192746/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sandor Demeter does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
There has been a monumental policy shift in paying blood plasma donors in Canada.
Sandor Demeter, Associate Professor, Community Health Sciences, Rady Faculty of Health Sciences, University of Manitoba
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/191053
2022-10-21T12:39:05Z
2022-10-21T12:39:05Z
Why are so many people delighted by disgusting things?
<figure><img src="https://images.theconversation.com/files/490728/original/file-20221019-19-xxwcfm.jpg?ixlib=rb-1.1.0&rect=140%2C60%2C6569%2C4406&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">In what's called 'benign masochism,' some people find the feeling of disgust pleasurable.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/folliculitis-on-human-skin-royalty-free-image/1289667569?phrase=popping pimple close-up&adppopup=true">Ocskaymark/iStock via Getty Images.</a></span></figcaption></figure><p>Halloween is a time to embrace all that is disgusting, from bloody slasher films to haunted houses full of fake guts and gore. </p>
<p>But the attraction to stuff that grosses us out goes beyond this annual holiday. </p>
<p>Flip through TV channels and you’ll come across <a href="https://deepblue.lib.umich.edu/handle/2027.42/97960">“adventurous eating” programs</a>, in which hosts and contestants are served all manner of stomach-clenching foods; reality shows that take a deep dive into the work of <a href="https://www.youtube.com/watch?v=1MFlKkanI6Q">pimple-popping dermatologists</a>; and <a href="https://www.manchesterhive.com/view/9781526130525/9781526130525.00017.xml">gross-out comedies</a> that deploy tasteless humor – think vomiting and urination – to make viewers laugh. </p>
<p>You can see this in other forms of media, as well. In romance novels, for example, you can find portrayals of consensual <a href="https://link.springer.com/article/10.1007/s12119-016-9386-6">sibling incest</a> that are designed to titillate the reader. And, most extreme of all, there are internet <a href="https://link.springer.com/chapter/10.1007/978-3-319-53856-3_13">shock sites</a> that host real footage of death and dismemberment for those who want to seek it out. </p>
<p>It isn’t just a recent media phenomenon, either. Early modern England has a similar culture of disgust, which I’ve <a href="https://www.bloomsbury.com/us/shakespeare-and-disgust-9781350213982/">written about in a forthcoming book</a>.</p>
<p>Why are so many people drawn to things that should, by all rights, compel them to turn away in horror? Modern science has an answer, and it has everything to do with how the emotion of disgust fundamentally works.</p>
<h2>What is disgust?</h2>
<p>Disgust is fundamentally an <a href="https://www.google.com/books/edition/Handbook_of_Emotions_Fourth_Edition/WBlKDwAAQBAJ?hl=en&gbpv=1&dq=Handbook+of+Emotions,+Fourth+Edition&printsec=frontcover">emotion of avoidance</a>: It signals that something might be harmful to your body, and encourages you to avoid it.</p>
<p>Scientists believe that disgust originally concerned food; <a href="https://www.google.com/books/edition/The_Expression_of_the_Emotions_in_Man_an/NWAJAAAAQAAJ?hl=en&gbpv=1&dq=%22how+readily+this+feeling+is+excited+by+anything+unusual%22&pg=PA257&printsec=frontcover">Charles Darwin noted</a> “how readily this feeling is excited by anything unusual in the appearance, odour, or nature of our food.” According to this theory, it slowly evolved to guard over all sorts of things that might put you in contact with dangerous pathogens, whether via disease, animals, bodily injury, corpses or sex. </p>
<p>What’s more, disgust seems to have evolved further to regulate things that are symbolically harmful: violations of morals, cultural rules and cherished values. This is why some people might say they’re “disgusted” by an act of racism.</p>
<p>Because of these regulatory functions, disgust is often known as the “<a href="https://www.google.com/books/edition/Disgust/91AGYNrUBDMC?hl=en&gbpv=1&dq=Disgust:+The+Gatekeeper+Emotion&printsec=frontcover">gatekeeper emotion</a>,” the “<a href="https://journals.sagepub.com/doi/10.1177/1368430212471738">exclusionary emotion</a>” or the “<a href="https://www.researchgate.net/publication/326223791_The_body_and_soul_emotion_-_The_role_of_Disgust_in_intergroup_relations">body and soul emotion</a>.”</p>
<h2>The allure of disgust</h2>
<p>How, then, do we account for the fact that disgusting things can sometimes captivate us? </p>
<p>Psychological research suggests that <a href="https://www.doi.org/10.1111/jcom.12094">disgusting stimuli both capture and retain your attention</a> more effectively than emotionally neutral stimuli do. </p>
<p><a href="https://www.doi.org/10.1111/jcom.12094">According to media scholars Bridget Rubenking and Annie Lang</a>, this likely happens because, from an evolutionary perspective, it seems that “an attentional bias toward disgust – no matter how aversive – would better equip humans to avoid harmful substances.” So although disgust can be an unpleasant feeling, the emotion has evolved to simultaneously seize people’s attention. </p>
<p>But disgusting things don’t just capture your attention; you can even enjoy them.</p>
<p>Psychologist <a href="https://deepblue.lib.umich.edu/handle/2027.42/97960">Nina Strohminger suggests</a> that the pleasurable features of disgust may be an instance of what has been called “<a href="https://www.doi.org/10.1007/BF00995932">benign masochism</a>” – the human tendency to seek out seemingly “negative” experiences for the purposes of enjoying “constrained risks,” such as riding a roller coaster or eating extremely spicy foods. </p>
<p>According to Strohminger, it seems “possible that any negative feeling has the potential to be enjoyable when it is stripped of the belief that what is happening is actually bad, leaving behind physiological arousal that is, in itself, exhilarating or interesting.”</p>
<p>So not only are you predisposed to be captivated by disgusting things, there’s also a psychological mechanism that enables you, in the right circumstances, to enjoy them.</p>
<h2>Shakespearean disgust</h2>
<p>Celebrating and profiting off this attraction isn’t a product of the digital age. It was even happening in Shakespeare’s time.</p>
<p>The playwright’s notorious tragedy “<a href="https://www.folger.edu/titus-andronicus">Titus Andronicus</a>” contains as much gore as today’s slasher movies. According to <a href="https://www.jstor.org/stable/23102751">one estimate</a>, the play stages “14 killings, 9 of them on stage, 6 severed members, 1 rape (or 2 or 3, depending on how you count), 1 live burial, 1 case of insanity, and 1 of cannibalism – an average of 5.2 atrocities per act, or one for every 97 lines.”</p>
<p>When exploring the “problematic appeal of this play’s violence,” <a href="https://www.google.com/books/edition/The_Shattering_of_the_Self/UQtRzswqR58C?hl=en&gbpv=1&dq=Cynthia+Marshall,+The+Shattering+of+the+Self:+Violence,+Subjectivity,+and+Early+Modern+Texts&printsec=frontcover">literary critic Cynthia Marshall asks</a>, “Why would an audience, any audience, enjoy Titus’s reiteration of violence against the human body?” </p>
<figure class="align-center ">
<img alt="Woman in a white dress covered in blood." src="https://images.theconversation.com/files/490729/original/file-20221019-14-3mizfu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/490729/original/file-20221019-14-3mizfu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/490729/original/file-20221019-14-3mizfu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/490729/original/file-20221019-14-3mizfu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/490729/original/file-20221019-14-3mizfu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/490729/original/file-20221019-14-3mizfu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/490729/original/file-20221019-14-3mizfu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=377&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">‘Titus Andronicus’ is the most gruesome work in Shakespeare’s canon.</span>
<span class="attribution"><a class="source" href="https://cloudimages.broadwayworld.com/columnpiccloud/1250-f243b9ac7d5c86f64d892f42f22b6734.jpg">Broadway World</a></span>
</figcaption>
</figure>
<p>The answer, I believe, owes to the alluring nature of disgust that psychologists have documented. In early modern England, in fact, there was a cottage industry of disgust. </p>
<p>Large crowds viewed <a href="https://www.google.com/books/edition/Making_Murder_Public/iuCGDwAAQBAJ?hl=en&gbpv=1&dq=">public executions</a>, and the corpses of criminals were left hanged by chains for the public to gawk at. In open anatomy theaters, curious onlookers could watch doctors <a href="https://www.google.com/books/edition/Staging_Anatomies/5-VADgAAQBAJ?hl=en&gbpv=1&dq=Staging+Anatomies:+Dissection+and+Spectacle+in+Early+Stuart&pg=PT7&printsec=frontcover">perform autopsies</a>. In their shops, apothecaries displayed dismembered <a href="https://www.google.com/books/edition/Medicinal_Cannibalism_in_Early_Modern_En/ptTHAAAAQBAJ?hl=en&gbpv=1&dq=Noble,+Medicinal+Cannibalism&printsec=frontcover">human body parts</a>, before eventually mixing them into medicines – a practice scholars today call “medicinal cannibalism.” </p>
<p>And it is not simply that Elizabethans were desensitized, possessed of a different threshold for disgust. <a href="https://www.bloomsbury.com/us/shakespeare-and-disgust-9781350213982/">Contemporaries expressed</a> their revulsion, even as they found themselves drawn to them. After seeing a charred body hanging in a merchant’s warehouse, the <a href="https://www.google.com/books/edition/Diary_and_correspondance_of_Samuel_Pepys/Y28rNpS4FwIC?hl=en&gbpv=1&dq=I+never+saw+any+before,+and+there,+it+pleased+me+much,+though+an+ill+sight&pg=PA278&printsec=frontcover">diarist Samuel Pepys noted</a> that “it pleased me much, though an ill sight.”</p>
<p>Then, as now, disgusting things captivate our attention and can even give us enjoyment – and the horrors of a play like “Titus Andronicus” reflect the fact that Elizabethans lived in a culture that encouraged people to gaze upon disgusting objects, even as they felt the urge to turn away. Shakespeare’s audience, I think, embraced the repulsive pleasure, just as modern audiences do when viewing the latest film in the “<a href="https://www.halloweenmovie.com/">Halloween</a>” franchise.</p>
<p>The human emotion that shields you from harm equally allows you to take a perverse pleasure in the very things from which you need to be protected.</p><img src="https://counter.theconversation.com/content/191053/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Bradley J. Irish does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Going out of your way to get grossed out might seem like a contradiction of human nature. But it serves a strong evolutionary purpose.
Bradley J. Irish, Associate Professor of English, Arizona State University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/183521
2022-07-24T20:01:44Z
2022-07-24T20:01:44Z
People who lived in the UK in the ‘mad cow disease’ years may now be able to give blood. The risk of vCJD is tiny
<figure><img src="https://images.theconversation.com/files/466871/original/file-20220603-20-xfv97z.jpg?ixlib=rb-1.1.0&rect=0%2C2%2C998%2C444&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/woman-medical-mask-sits-chair-donates-2123764988">Shutterstock</a></span></figcaption></figure><p>From today, eligible people who were in the United Kingdom in the 80s and 90s will be able to donate blood in Australia again.</p>
<p>That’s because the risk of acquiring variant Creutzfeldt-Jakob disease (vCJD) from blood transfusions in Australia is incredibly tiny. </p>
<p>We calculated that risk was about one in 1.4 billion, <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/vox.13290">publishing our research</a> in the journal <em>Vox Sanguinis</em>.</p>
<p>The removal of restrictions, which have been in place for more than 20 years, means about 750,000 more Australians can now potentially donate blood.</p>
<p>This is at a time when there is a <a href="https://www.abc.net.au/news/2022-05-31/australia-blood-stocks-plummet-due-to-covid-flu/101113510">shortage of blood donations</a> due to donors sick with COVID or flu.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1531493334165823490"}"></div></p>
<h2>Remind me again, what is vCJD?</h2>
<p>Researchers identified vCJD as a new and emerging fatal neurological disease <a href="https://pubmed.ncbi.nlm.nih.gov/8598754/">in 1996</a>. It has since been associated with 233 cases <a href="https://pubmed.ncbi.nlm.nih.gov/11283320/">worldwide</a>, with 178 of those in the UK. </p>
<p>Once infected, people show no symptoms for many years. But when they do, there are psychiatric symptoms, such as depression. Then there are sensory symptoms, such as pain, followed by neurological abnormalities. People usually die about a year after symptoms start.</p>
<p>Transmission has been mainly via eating beef from cattle with bovine spongiform encephalitis (or BSE, commonly referred to as “mad cow disease”) in the UK during the 80s and 90s. </p>
<p>Mad cow disease had been spread by contaminated stock feed (cattle had been fed with contaminated beef products) before regulations were tightened and implemented, from 1996.</p>
<p>Over this time, an estimated <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7130755/">180,000</a> infected cattle had entered the UK human food chain.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/rare-and-deadly-creutzfeldt-jakob-disease-remains-a-bit-of-a-medical-mystery-44408">Rare and deadly, Creutzfeldt-Jakob disease remains a bit of a medical mystery</a>
</strong>
</em>
</p>
<hr>
<h2>How is this connected to giving blood?</h2>
<p>There is no easy test for vCJD and infected people don’t know they have it until they have symptoms. This pre-symptomatic phase can be as long as <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3310634/">several decades</a>. So there was speculation there could be unidentified people with vCJD, but exactly how many was unclear.</p>
<p>This is a potential public health issue as people who don’t know they have vCJD could transmit to others through blood, or tissue and organ donations.</p>
<p>This is why people who were in the UK between 1980 and 1996 for six months or more have been unable to give blood in Australia, since December 2000. Other countries had similar bans.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/466879/original/file-20220603-24-1esy45.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Blood bag hanging in operating theatre while surgeons operating" src="https://images.theconversation.com/files/466879/original/file-20220603-24-1esy45.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/466879/original/file-20220603-24-1esy45.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/466879/original/file-20220603-24-1esy45.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/466879/original/file-20220603-24-1esy45.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/466879/original/file-20220603-24-1esy45.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/466879/original/file-20220603-24-1esy45.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/466879/original/file-20220603-24-1esy45.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">People who didn’t know they had vCJD could have transmitted to others via a blood transfusion.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/giving-blood-during-operation-222697294">Shutterstock</a></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/from-animal-experiments-to-saving-lives-a-history-of-blood-transfusions-80391">From animal experiments to saving lives: a history of blood transfusions</a>
</strong>
</em>
</p>
<hr>
<h2>So what’s changed?</h2>
<p>Since the peak of the vCJD epidemic in 2000, when there were <a href="http://www.cjd.ed.ac.uk/sites/default/files/figs.pdf">28 deaths in the UK</a>, there has been a rapid decline in recorded cases, with only two worldwide since 2015. These numbers are much lower than modelled predictions. </p>
<p>Because there have been no BSE or vCJD cases in Australia, lower-than-predicted vCJD case numbers generally, and the ongoing change in the proportion of people in Australia who were exposed to vCJD, we recently reassessed the risk of vCJD in Australian blood donors.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/australias-ethnic-face-is-changing-and-so-are-our-blood-types-113454">Australia’s ethnic face is changing, and so are our blood types</a>
</strong>
</em>
</p>
<hr>
<h2>The risk is tiny, the benefits large</h2>
<p>We looked at a range of scenarios, including different assumptions about the numbers of people with vCJD, infectiousness and incubation periods.</p>
<p>Using modelling, we predicted a blood donation from an Australian with vCJD would occur once every 65 years, but this rate decreases over time.</p>
<p>If that donated blood was used in a transfusion today, there would be about a one in 1.4 billion chance of the recipient developing vCJD.</p>
<p>In other words, there is virtually no increased risk of vCJD transmission via transfusion (and this is decreasing). Lifting the ban on UK donors would increase the donor pool by 750,000 newly eligible people. </p>
<p>Assuming donation at the current rate, this would result in a gain of around 58,000 blood donations annually.</p>
<p>Our research was instrumental in supporting today’s opening up of blood donations, <a href="https://www.lifeblood.com.au/news-and-stories/media-centre/media-releases/tga-approval-lift-mad-cow-blood-donation-ban-people-who-lived-in-uk">as approved</a> by the Therapeutic Goods Administration earlier this year and subsequently supported by Australian governments.</p>
<p>The Food and Drug Administration has also <a href="https://www.fda.gov/regulatory-information/search-fda-guidance-documents/recommendations-reduce-possible-risk-transmission-creutzfeldt-jakob-disease-and-variant-creutzfeldt">recommended</a> removing similar restrictions on blood donors in the United States.</p>
<hr>
<p><em>The authors acknowledge the assistance of Veronica Hoad and Alison Gould from Lifeblood in drafting and reviewing the article.</em></p>
<p><em>Contact <a href="https://www.lifeblood.com.au">Lifeblood</a> to donate blood in Australia.</em></p><img src="https://counter.theconversation.com/content/183521/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Clive Seed is Senior Blood Safety Analyst, Clinical Services and Research, Australian Red Cross Lifeblood.</span></em></p><p class="fine-print"><em><span>This work was funded by and NH&MRC Partnership Grant (APP1151959)</span></em></p><p class="fine-print"><em><span>Hamish McManus does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
We calculated there was a one in 1.4 billion chance of someone contracting vCJD from a blood transfusion. And that risk will get even smaller with time.
Hamish McManus, Biostatistician, Kirby Institute, UNSW Sydney
Clive Seed, Adjunct lecturer in allograft transmissible infections, medical school (surgery), The University of Western Australia
Matthew Law, Professor and Program Head, Biostatistics and Databases Program, Kirby Institute, UNSW Sydney
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/179430
2022-06-03T12:17:46Z
2022-06-03T12:17:46Z
Bed bugs’ biggest impact may be on mental health after an infestation of these bloodsucking parasites
<figure><img src="https://images.theconversation.com/files/466798/original/file-20220602-24-e1ajb7.jpg?ixlib=rb-1.1.0&rect=597%2C134%2C1546%2C704&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Dozens of bed bugs and their eggs and fecal material on a metal bed frame.</span> <span class="attribution"><span class="source">Jerome Goddard</span></span></figcaption></figure><p>Bed bugs are back with a vengeance. After an absence of around 70 years, thanks to effective pesticides such as DDT, they’ve been popping up in fancy hotels, spas, department stores, subway trains, movie theaters – and, of course, people’s homes.</p>
<p><a href="https://scholar.google.com/citations?user=JVfeckwAAAAJ&hl=en&oi=ao">I’m a public health entomologist</a>. In the course of my work, I’ve studied these little bloodsuckers, even letting bed bugs feast on my own appendages in the name of science. <a href="https://www.cc.com/video/5klha6/the-colbert-report-threatdown-bedbugs-environmentalists-jerome-goddard">No one likes dealing with bed bugs</a> – and there are ways to minimize your chances of needing to.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/466795/original/file-20220602-22-q1mksl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="closeup of the front underside of a brown insect" src="https://images.theconversation.com/files/466795/original/file-20220602-22-q1mksl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/466795/original/file-20220602-22-q1mksl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=408&fit=crop&dpr=1 600w, https://images.theconversation.com/files/466795/original/file-20220602-22-q1mksl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=408&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/466795/original/file-20220602-22-q1mksl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=408&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/466795/original/file-20220602-22-q1mksl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=513&fit=crop&dpr=1 754w, https://images.theconversation.com/files/466795/original/file-20220602-22-q1mksl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=513&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/466795/original/file-20220602-22-q1mksl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=513&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Colorized scanning electron microscopic image reveals the underside of a bed bug, including the proboscis (purple) and two eyes (red).</span>
<span class="attribution"><a class="source" href="https://phil.cdc.gov/Details.aspx?pid=11739">CDC/Janice Haney Carr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Know thy bed bug enemy</h2>
<p>The common bed bug, <em>Cimex lectularius</em>, has been a parasite of humans for thousands of years. Historically, these tiny bloodsuckers were common in human dwellings worldwide, giving the old saying “sleep tight, don’t let the bed bugs bite” real meaning. They had nearly disappeared in developing countries until the mid-1990s, when they began <a href="https://doi.org/10.1093/ae/52.2.102">making a comeback</a> because of restriction or loss of certain pesticides, changes in pest control practices and increased international travel. <a href="https://medent.usyd.edu.au/bedbug/papers/doggett_icup2008.pdf">In many areas</a> around the world, they are now <a href="https://npmapestworld.org/default/assets/File/publicpolicy/executivesummaryreleasetomembersFINAL.pdf">a major urban pest</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/455860/original/file-20220401-30316-7hdfi7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="brown insect on white human skin, eating" src="https://images.theconversation.com/files/455860/original/file-20220401-30316-7hdfi7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/455860/original/file-20220401-30316-7hdfi7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/455860/original/file-20220401-30316-7hdfi7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/455860/original/file-20220401-30316-7hdfi7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/455860/original/file-20220401-30316-7hdfi7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/455860/original/file-20220401-30316-7hdfi7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/455860/original/file-20220401-30316-7hdfi7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A bed bug extends its beaklike proboscis to feed on human blood.</span>
<span class="attribution"><span class="source">Jerome Goddard</span></span>
</figcaption>
</figure>
<p>Adult bed bugs are less than a quarter-inch long (about 5 mm), oval-shaped and flattened, resembling unfed ticks or small cockroaches. Tucked backward underneath their head they have a long proboscis – a tubular mouthpart they can extend to take a blood meal. A bed bug needs only between three and 10 minutes to <a href="http://ipm.ucanr.edu/PMG/PESTNOTES/pn7454.html">consume up to six times its weight in blood</a> in a single meal.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/455865/original/file-20220401-11604-l3fugz.gif?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Small insect sits on a dime" src="https://images.theconversation.com/files/455865/original/file-20220401-11604-l3fugz.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/455865/original/file-20220401-11604-l3fugz.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=537&fit=crop&dpr=1 600w, https://images.theconversation.com/files/455865/original/file-20220401-11604-l3fugz.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=537&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/455865/original/file-20220401-11604-l3fugz.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=537&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/455865/original/file-20220401-11604-l3fugz.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=675&fit=crop&dpr=1 754w, https://images.theconversation.com/files/455865/original/file-20220401-11604-l3fugz.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=675&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/455865/original/file-20220401-11604-l3fugz.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=675&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A yellowish-white first-stage bed bug nymph is tiny.</span>
<span class="attribution"><span class="source">Jerome Goddard</span></span>
</figcaption>
</figure>
<p>Adults are reddish brown, while the babies are extremely tiny and yellowish-white in color. They hide in cracks and crevices, generally within a few feet of a bed, coming out only to feed on an unsuspecting host. Then they run back to their hiding places, where they mate and lay eggs. </p>
<p>Houses can become infested with thousands of the little bloodthirsty pests in the mattress and box spring, where they leave telltale black fecal spots. In severe infestations there may be thick feces, hundreds of shed skins and eggs several millimeters thick.</p>
<h2>Biggest health impacts may be psychological</h2>
<p>Bed bugs have been <a href="https://doi.org/10.2307/4591852">suspected in the transmission</a> of more than 40 disease organisms, but there is <a href="https://doi.org/10.1001/jama.2009.405">little evidence bed bugs transmit human pathogens</a>, with the <a href="https://doi.org/10.4269/ajtmh.14-0483">possible exception of the microorganism that causes Chagas disease</a>. Extreme infestations can, in rare cases, lead to <a href="https://doi.org/10.1503/cmaj.090482">blood loss severe enough to cause anemia</a>.</p>
<p>Their <a href="https://www.cdc.gov/parasites/bedbugs/faqs.html">principal medical impacts</a> are related to nuisance biting and the associated itching and inflammation. The most common bite reactions are <a href="https://doi.org/10.1016/j.parint.2006.12.002">itchy red spots at feeding sites</a> that usually go away in a week or so. Some people have <a href="https://pubmed.ncbi.nlm.nih.gov/11534921/">complex skin</a> <a href="https://doi.org/10.1007/978-1-4471-1356-0">reactions</a>, <a href="https://doi.org/10.4314/wajm.v21i4.27994">including hives</a> and <a href="https://doi.org/10.1016/j.amjmed.2011.11.020">blisters</a>, or allergic responses.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/455870/original/file-20220401-11-2vzeac.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="pink irritated patch on white skin of an arm" src="https://images.theconversation.com/files/455870/original/file-20220401-11-2vzeac.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/455870/original/file-20220401-11-2vzeac.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/455870/original/file-20220401-11-2vzeac.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/455870/original/file-20220401-11-2vzeac.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/455870/original/file-20220401-11-2vzeac.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/455870/original/file-20220401-11-2vzeac.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/455870/original/file-20220401-11-2vzeac.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The marks from bed bug bites can persist on human skin for several days.</span>
<span class="attribution"><span class="source">Jerome Goddard and Kristine T. Edwards</span></span>
</figcaption>
</figure>
<p>Then there’s bed bugs’ <a href="http://dx.doi.org/10.1136/bmjopen-2012-000838">emotional and</a> <a href="https://doi.org/10.1016/j.amjmed.2011.08.010">psychological effects on their victims</a>. Run-ins with these parasites can trigger nervousness, anxiety and insomnia. Bed bugs commonly come with a side effect of constant worrying and feelings of shame. <a href="http://habitatservices.org/wp-content/uploads/PDF3-Bed-Bugs-Are-Back-Report.pdf">One distressed Canadian expressed it this way</a>:</p>
<blockquote>
<p>“To be honest, until you go through [an infestation], you have no idea just how horrifying it really is. It is just natural for you to become paranoid; you lose sleep, you end up dreaming and thinking about bed bugs – they just consume every fiber of your being.”</p>
</blockquote>
<p><a href="http://hdl.handle.net/1866/10783">One study of people exposed to bed bugs</a> found about half reported sleep difficulties and social isolation associated with the infestation.</p>
<p>My colleague and I analyzed <a href="https://doi.org/10.1016/j.amjmed.2011.08.010">135 internet posts concerning bed bug infestations</a>. The majority, 81% of the posts, reported three or more behaviors commonly associated with post-traumatic stress disorder – reactions like reexperiencing the event through intrusive memories and nightmares, startle responses and hypervigilance. Six posts detailed intense and repeated cleanings of homes or offices. Five posts reported persistent avoidance of people, activities and places that might lead to transmission of insects or arouse recollections of the original encounter. And five posts detailed suicidal thoughts or attempts. There are other anecdotal reports of <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3700489/">suicides</a> or drug overdoses by people struggling with bed bugs.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/455868/original/file-20220401-19-26i6dl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Bed bugs and fecal spots on a bed sheet." src="https://images.theconversation.com/files/455868/original/file-20220401-19-26i6dl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/455868/original/file-20220401-19-26i6dl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/455868/original/file-20220401-19-26i6dl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/455868/original/file-20220401-19-26i6dl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/455868/original/file-20220401-19-26i6dl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/455868/original/file-20220401-19-26i6dl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/455868/original/file-20220401-19-26i6dl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">You can check for the telltale marks of a bed bug infestation on a bed’s mattress and box spring.</span>
<span class="attribution"><a class="source" href="https://www.acq.osd.mil/eie/afpmb/docs/techguides/tg44.pdf">H.J. Harlan, U.S. Armed Forces Pest Management Board</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>How to protect yourself from bed bugs</h2>
<p>Not every hotel room has bed bugs, but some do. Simple precautions can help protect you and your belongings from infestation. </p>
<p>Leave all unnecessary items in your vehicle, such as extra clothing, gear and equipment. When first entering your hotel room, place luggage in the bathroom until you have had a chance to inspect the place. Pull back sheets and check the mattress and box spring for live bed bugs or black fecal spots. If any bugs or suspicious signs of infestation are found, go to the front desk and request another room. Because bed bugs don’t usually travel far on their own, other nonadjacent rooms may be perfectly clean of the parasites.</p>
<p>Keeping bed bugs out of houses and apartments can be difficult, especially if you travel a lot. After traveling, unpack luggage outside or in the garage, and wash all clothing from the luggage in hot water and dry on high heat if possible. A dryer is a great tool in the fight against bed bugs. Bed bugs can also hitch a ride into your home on used furniture or items purchased at secondhand stores or garage sales. Be sure to disinfect – more precisely “dis-insect” – those kinds of items. It’s a good idea to never purchase used mattresses or beds, no matter how good a bargain. </p>
<p>What can you do if you are forced to confront these bloodsuckers? A bed bug infestation found in a hotel room should immediately be reported to management. If you find bed bugs in your home, or in secondhand purchases, it’s best not to try to spray them yourself with over-the-counter pesticides. My recommendation is to contact a competent pest exterminator, who will treat the space with pesticides, use complex heat systems or both to kill the bugs.</p>
<p>Try not to panic. Keep in mind that bed bugs are only insects. They’re not magic. Believe me, they can be killed and eliminated from a dwelling.</p><img src="https://counter.theconversation.com/content/179430/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jerome Goddard does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Bed bugs are pretty much universally reviled. But a public health entomologist explains how – while potentially traumatizing to deal with – they aren’t likely to make you sick.
Jerome Goddard, Extension Professor of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/182112
2022-05-06T12:33:22Z
2022-05-06T12:33:22Z
COVID-19 official counts can miss mild cases – here’s how serosurveys that analyze blood for signs of past infection can help
<figure><img src="https://images.theconversation.com/files/461644/original/file-20220505-17-7g5jqg.jpg?ixlib=rb-1.1.0&rect=50%2C62%2C2413%2C1584&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Researchers can test blood samples taken for other reasons to see if patients have previously had COVID-19.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/leila-kohbodi-and-melvin-narciso-prepare-viles-of-blood-news-photo/563577159">Don Bartletti/Los Angeles Times via Getty Images</a></span></figcaption></figure><p><em>It’s an eye-catching statistic: <a href="http://dx.doi.org/10.15585/mmwr.mm7117e3">58% of the whole population and 75% of kids</a> in the U.S. <a href="https://covid.cdc.gov/covid-data-tracker/#national-lab">had been infected by the coronavirus</a> by the end of February 2022. That’s a pretty big jump from the official case count that hovered <a href="https://www.cdc.gov/coronavirus/2019-ncov/covid-data/covidview/past-reports/03042022.html">around a quarter of Americans</a> having been diagnosed with COVID-19. A report from the U.S. Centers for Disease Control and Prevention based these higher proportions on what’s called a <a href="https://www.cdc.gov/coronavirus/2019-ncov/cases-updates/about-serology-surveillance.html">serosurvey: a study that looks at people’s blood</a> to see if they’ve had a particular illness.</em></p>
<p><em><a href="https://scholar.google.com/citations?user=eNuipnQAAAAJ&hl=en&oi=ao">Isobel Routledge</a> is an infectious disease epidemiologist <a href="https://doi.org/10.1038/s41467-021-23651-6">who uses serosurveys</a> <a href="https://doi.org/10.1038/s41467-022-30051-x">in her own research</a>. Here she explains the science behind the approach and what a serosurvey can – and can’t – tell you.</em></p>
<h2>What does a serosurvey look for?</h2>
<p>When you’re infected by or vaccinated against a pathogen, like the SARS-CoV-2 virus that causes COVID-19, your body produces antibodies to fight it. Some types of antibodies remain in your blood long after you’ve recovered. During a serosurvey, researchers look in blood samples for these long-lasting antibodies. They act as markers of past exposure to the pathogen.</p>
<p>The power of this type of study is that it can reveal whether someone was previously infected with a particular pathogen, even if they didn’t have symptoms or take a test. Having specific antibodies in your blood can also mean you’re immune to a certain disease – scientists are still investigating what the <a href="https://doi.org/10.1038/s41591-021-01432-4">markers of protection against COVID-19</a> might be, though.</p>
<p>If they test enough blood samples – ideally through a random sample of the population – researchers can use a serosurvey to estimate the proportion of a population that has been previously infected or vaccinated, and in some cases <a href="https://doi.org/10.1128/CVI.00131-10">estimate the proportion of the population that is immune</a> to a particular disease.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/461646/original/file-20220505-23-zgjut1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="person holds up a vaccination sticker next to arm with bandaid" src="https://images.theconversation.com/files/461646/original/file-20220505-23-zgjut1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/461646/original/file-20220505-23-zgjut1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/461646/original/file-20220505-23-zgjut1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/461646/original/file-20220505-23-zgjut1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/461646/original/file-20220505-23-zgjut1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/461646/original/file-20220505-23-zgjut1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/461646/original/file-20220505-23-zgjut1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Researchers can focus on specific antibodies that your body makes after catching COVID-19 that are different from the ones triggered by vaccination.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/year-old-newly-vaccinateda-against-covid-19-holds-up-a-news-photo/1233291434">Scott Heins/Getty Images</a></span>
</figcaption>
</figure>
<h2>Can serosurveys tell the difference between an infection and vaccination?</h2>
<p>Yes. In a recent study, my colleagues and I wanted to separate out those who had been previously infected with SARS-CoV-2 and those who had been vaccinated. So we looked for <a href="https://doi.org/10.1038/s41467-022-30051-x">two different bio-markers</a> in the blood samples.</p>
<p>Vaccines administered in the U.S. <a href="https://theconversation.com/what-happens-when-the-covid-19-vaccines-enter-the-body-a-road-map-for-kids-and-grown-ups-164624">trigger your body to produce antibodies</a> to a particular part of the SARS-CoV-2 virus called the spike protein. If we identified antibodies to the spike protein, that means a person could have been vaccinated, been previously infected with SARS-CoV-2, or both.</p>
<p>When people are naturally infected with SARS-CoV-2, they produce antibodies to another part of the coronavirus called the nucleocapsid protein. If we identified antibodies to the nucleocapsid protein, then we knew the patient had previously contracted COVID-19. Vaccination doesn’t trigger these particular antibodies. The CDC study used this type of test to separate out only those who were previously infected. </p>
<h2>How far back in time can this method ‘see’?</h2>
<p>Antibodies take a few weeks to build up to their maximum level. Then their concentration wanes in the weeks and months after exposure to an infectious disease.</p>
<p>Colleagues of mine at the University of California, San Francisco are currently studying the dynamics of this process for COVID-19 in the <a href="https://doi.org/10.1126/sciadv.abh3409">Long-term Impact of Infection With Novel Coronavirus (LIINC)</a> study. Since March 2020, they’ve been following volunteers who’ve recovered from COVID-19, collecting blood and saliva samples at regular intervals to monitor changes in antibody levels.</p>
<p>Based on over a year of observations, the team estimated that someone who had previously had COVID-19 could test negative on an antibody test on average anywhere between 96 and 925 days after their infection. It seems to depend a lot on disease severity and the specific test used.</p>
<p>Several tests, including the <a href="http://dx.doi.org/10.15585/mmwr.mm7117e3">one used in the recent CDC study</a>, showed no evidence of any decrease in detecting antibodies over six months of observation. Additional studies using a different test found that the majority of patients had detectable levels of nucleocapsid antibodies in the blood at <a href="https://doi.org/10.1016/S0140-6736(21)00238-5">a year</a> and at <a href="https://doi.org/10.3389/fimmu.2022.829665">16 months</a> after infection.</p>
<p>The CDC study looked at blood samples collected between September 2021 and February 2022, which was at most two years after anyone would have contracted COVID-19. Based on current evidence, I’d not too concerned about a lot of false negatives based on how long ago people were infected. However, if there were some missed infections in this study, that would mean that the true proportion of the population that was previously infected is slightly more than the estimated 58%. </p>
<h2>Why are serosurveys important to do?</h2>
<p>Traditional disease surveillance measures, such as counts of reported cases or positive tests, are super important for monitoring the spread and burden of infectious diseases. But for a disease like COVID-19 that can cause lots of asymptomatic and mild infections, the numbers of reported cases may represent only the tip of the iceberg.</p>
<p>Case counts often miss asymptomatic infections, as well as infections in those who do not have access to health care or testing. It can also be tricky to compare data from disease surveillance systems over time and in different places.</p>
<p>Serosurveys are a way of capturing asymptomatic and unreported infections, and a well-designed serosurvey can often provide a “truer” picture of infection history in a population than case counts. But serosurveys have their own, separate biases.</p>
<h2>What factors make a serosurvey tricky to do well?</h2>
<p>You need to consider who is in the group you’ve taken your samples from and whether they’re representative of the wider U.S. in terms of demographics, including location, age, biological sex, race/ethnicity, socioeconomic status, occupation and so on. Otherwise your finding might not be generalizable to the population as a whole.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/461647/original/file-20220505-22-k709u8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="people donating blood at a blood drive" src="https://images.theconversation.com/files/461647/original/file-20220505-22-k709u8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/461647/original/file-20220505-22-k709u8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/461647/original/file-20220505-22-k709u8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/461647/original/file-20220505-22-k709u8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/461647/original/file-20220505-22-k709u8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/461647/original/file-20220505-22-k709u8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/461647/original/file-20220505-22-k709u8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The people who donate blood may be different from the population as a whole, so a survey based largely on their samples may not be representative of the larger population.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/phlebotomist-herbert-collins-draws-blood-from-victoria-news-photo/1224220324">Scott Olson/Getty Images</a></span>
</figcaption>
</figure>
<p>Many studies, including the CDC report and my own work, rely on what’s called convenience sampling. We piggyback on blood samples that were initially collected for clinical testing or blood donation and then reuse them for the serosurvey. This means we’re only including people who are getting blood tests for health conditions or checkups, or those donating blood. We’re missing out on parts of the U.S. population who don’t access health care or donate blood. </p>
<p><a href="https://doi.org/10.1038/d41586-022-00336-8">Randomly selecting a representative sample</a> of the entire population can get around those biases. However, this kind of study is extremely expensive and time-consuming to carry out. Just a small number have been <a href="https://doi.org/10.1371/journal.pone.0267322">conducted at the state level</a>.</p>
<p>A further challenge is defining the threshold for considering an antibody test as positive or negative. These tests measure the concentration of a particular antibody in the sample. Antibody responses can vary depending on the <a href="https://doi.org/10.1093/infdis/jiaa523">severity of illness and time since infection</a>. If researchers set the cutoff for a positive result too high, it can lead to more false negatives.</p>
<p>The recent CDC serosurvey acknowledged some limitations in how generalizable it really is. No data on race/ethnicity was available to weight the study results, and the study was likely to have over-represented people who could seek health care. If the antibody test was less accurate with mild or older infections, the true proportion of the population that was previously exposed could have been even higher than the 58% estimate. Despite these limitations, this study does provide hugely valuable data for tracking changes in SARS-CoV-2 transmission over time.</p><img src="https://counter.theconversation.com/content/182112/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Isobel Routledge receives funding from the National Institutes of Health. </span></em></p>
Your blood can hold a record of past illnesses. That information can reveal how many people have had a certain infection – like 58% of Americans having had COVID-19 by the end of February 2022.
Isobel Routledge, Postdoctoral Scholar in Medicine, University of California, San Francisco
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/175906
2022-02-03T13:11:31Z
2022-02-03T13:11:31Z
Heading into the third year of the pandemic, the US blood supply is at a 10-year low
<figure><img src="https://images.theconversation.com/files/443904/original/file-20220201-21-1mjhmc5.jpg?ixlib=rb-1.1.0&rect=209%2C83%2C6779%2C3845&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Blood donations have dropped at the same time that the need for blood is soaring. </span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/red-blood-cells-flowing-through-the-blood-stream-royalty-free-image/1280727099?adppopup=true">ExperienceInteriors/E+ via Getty Images</a></span></figcaption></figure><p>The blood supply in the U.S. is now at its lowest level in <a href="https://www.keyc.com/2022/01/05/nations-blood-supply-reaches-10-year-low/">over a decade</a>.</p>
<p>Many of the nation’s blood centers currently have only a <a href="https://www.npr.org/2022/01/17/1073661375/red-cross-declares-a-blood-crisis-as-supply-runs-out-at-hospitals-and-blood-bank">one-day supply of some blood types in inventory</a>. This is dangerous because blood transfusions are needed for many surgeries. Blood is also used in the treatment of diseases like sickle cell anemia and certain cancers – and is critical to help those who suffer injuries from accidents or disasters.</p>
<p>In January 2022, the American Red Cross declared its <a href="https://thehill.com/policy/healthcare/public-global-health/589152-red-cross-declares-first-national-blood-crisis">first-ever national blood crisis</a>. A <a href="https://www.ama-assn.org/press-center/press-releases/aha-ama-ana-joint-statement-blood-shortages">joint statement</a> by the American Hospital Association, the American Medical Association and the American Nurses Association said that the “severity and duration of this shortage could significantly jeopardize the ability of health care providers to meet the many urgent needs of our patients and communities.”</p>
<p>A consistent supply of blood is essential to the nation’s health. Blood is a precious lifesaving product that cannot be manufactured but must be donated. No substitute for blood exists. </p>
<p>Each day the U.S. needs about 29,000 units of red blood cells, 5,000 units of platelets and <a href="https://dx.doi.org/10.1016%2Fj.ajem.2020.06.058">6,500 units of plasma</a>, according to the <a href="https://www.redcrossblood.org/donate-blood/how-to-donate/how-blood-donations-help/blood-needs-blood-supply.html">American Red Cross</a>. The average blood transfusion is for three units, with a victim of a car accident requiring as many as 100. A single donation can help more than one patient. Convalescent plasma may even be used as <a href="https://www.washingtonpost.com/health/2021/12/21/covid-treatment-convalescent-plasma/">a treatment against COVID-19</a>, a possibility <a href="https://doi.org/10.1007/s43069-021-00072-1">our team has been researching</a>.</p>
<p><a href="https://people.umass.edu/nagurney/">I am a professor and director</a> of the Virtual Center for Supernetworks at the University of Massachusetts Amherst. <a href="https://scholar.google.com/citations?user=ecFsBp0AAAAJ&hl=en">My expertise is supply chains</a>, including <a href="https://link.springer.com/book/10.1007/978-1-4614-6277-4">perishable product supply chains</a> such as blood. The COVID-19 pandemic, heading into its third year, has exacerbated the challenges associated with the nation’s blood supply chains. Let me explain.</p>
<h2>Two years of dramatic change</h2>
<p>At the <a href="https://theconversation.com/how-coronavirus-is-upsetting-the-blood-supply-chain-133424">onset of the pandemic</a> in the winter of 2020, with growing fear and uncertainty, blood collections at many schools and other sites that traditionally hosted mobile blood drives closed. Throughout the nation, elective surgeries were canceled and procedures <a href="https://dx.doi.org/10.1016%2Fj.cll.2020.08.013">to preserve blood put into place</a>. </p>
<p>Even before the pandemic, blood service organizations faced many challenges – including economic ones – and the U.S. blood supply chain was going through major shifts. In pre-pandemic times, less than 10% of the U.S. population would donate blood in a given year, although 38% were eligible. Moreover, blood is perishable,<a href="https://supernet.isenberg.umass.edu/articles/CompetitionforBloodDonations.pdf"> with red blood cells lasting 42 days, and platelets only five days</a>, so regular replenishment is essential. </p>
<p>But in the past two years, since the World Health Organization <a href="https://www.who.int/director-general/speeches/detail/who-director-general-s-opening-remarks-at-the-media-briefing-on-covid-19---11-march-2020">declared the COVID-19 pandemic</a>, unforeseen ripple effects have resulted in an <a href="https://www.boston.com/news/health/2022/01/14/an-unprecedented-shortage-hospitals-in-massachusetts-are-desperate-for-blood-donors/">immense demand for blood</a>. Many people delayed medical treatment and may now be <a href="https://www.mskcc.org/news/covid-19-has-caused-national-blood-shortage-people-cancer-need-your-help">suffering from more advanced disease</a>. An increase in <a href="https://doi.org/10.1038/s41598-021-98813-z">gun violence</a>, <a href="https://www.ama-assn.org/system/files/issue-brief-increases-in-opioid-related-overdose.pdf">drug overdoses</a>, <a href="https://www.latimes.com/world-nation/story/2021-12-08/traffic-deaths-surged-during-covid-19-pandemic-heres-why">automobile accidents</a> – some due to driving under the influence as a consequence of pandemic-induced stress and challenges – and <a href="https://doi.org/10.1186/s12888-021-03570-y">other trauma</a> during the pandemic have also led to escalating demand for blood. </p>
<p>The American Red Cross <a href="https://www.boston.com/news/health/2022/01/14/an-unprecedented-shortage-hospitals-in-massachusetts-are-desperate-for-blood-donors/">reports that</a> since March 2020, blood donations have decreased by 10%, with a decrease of 62% in college and high school blood drives as many of those locations went remote. This age group represented about a quarter of all the donors in 2019, with a drop to about 10% of all donors during the pandemic. </p>
<p>Most recently, donors who have tested positive with the <a href="https://theconversation.com/alpha-then-delta-and-now-omicron-6-questions-answered-as-covid-19-cases-once-again-surge-across-the-globe-174703">highly transmissible omicron variant</a> have had to cancel <a href="https://news.wttw.com/2022/01/17/red-cross-warns-national-blood-crisis-due-supply-shortage">scheduled appointments for donating blood</a>. The U.S. Food and Drug Administration recently released guidelines with updated information for blood establishments regarding <a href="https://www.fda.gov/vaccines-blood-biologics/safety-availability-biologics/updated-information-blood-establishments-regarding-covid-19-pandemic-and-blood-donation">blood donations in the pandemic</a>. Donating blood is itself safe and, importantly, according to the FDA, globally there have been “no reported cases of transfusion-transmitted coronavirus, including SARS-CoV-2.”</p>
<p>The American Red Cross provides about 40% of the <a href="https://www.redcrossblood.org/donate-blood/how-to-donate/how-blood-donations-help/blood-needs-blood-supply.html">blood and blood components that are needed in the U.S.</a>. Donors can also donate blood at local community blood centers or hospitals, at <a href="https://www.vitalant.org/#">Vitalant</a> – formerly United Blood Services – or at member organizations of <a href="https://americasblood.org/">America’s Blood Centers</a>. These make up North America’s largest network of nonprofit community blood centers and operate more than 600 blood donation collection sites.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/443908/original/file-20220201-13-z8dv3z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A person holds an I Love You sign and small blood bag, with nurses and blood donors in the background." src="https://images.theconversation.com/files/443908/original/file-20220201-13-z8dv3z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/443908/original/file-20220201-13-z8dv3z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/443908/original/file-20220201-13-z8dv3z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/443908/original/file-20220201-13-z8dv3z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/443908/original/file-20220201-13-z8dv3z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/443908/original/file-20220201-13-z8dv3z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/443908/original/file-20220201-13-z8dv3z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Blood donations have dropped by 10% since the beginning of the pandemic, according to the American Red Cross.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/blood-donation-royalty-free-image/1180246381?adppopup=true">Kmatta/Moment via Getty Images</a></span>
</figcaption>
</figure>
<h2>Not just numbers</h2>
<p>When it comes to blood shortages, people’s lives are on the line, and the stories are very personal. </p>
<p>A young pregnant mother in Louisiana who was suffering from COVID-19 and internal bleeding survived just long enough to see her <a href="https://www.knoe.com/2022/01/28/west-monroe-woman-loses-daughter-speaks-about-importance-blood-donation/">newborn daughter, thanks to blood donations</a>. An 11-year-old girl in West Virginia who is battling bone cancer <a href="https://www.wtrf.com/news/local-news/11-year-old-girl-battling-bone-cancer-during-nationwide-blood-shortage-crisis/">has received 18 blood transfusions</a>. An 8-year-old girl in Texas <a href="https://www.ksat.com/news/local/2022/01/13/doctors-and-patients-worry-during-nationwide-blood-crisis/">is suffering from T-cell leukemia </a> and relies on blood donations, but numerous blood drives in her area were canceled. These are just a few examples.</p>
<p>And the ability to receive regular transfusions is a <a href="https://wtop.com/local/2022/01/donated-blood-thats-direly-needed-who-does-it-help/">matter of life or death for those with certain illnesses</a>. </p>
<h2>The many links involved in blood supply</h2>
<p>The <a href="https://doi.org/10.1007/s10287-011-0133-z">blood supply chain is incredibly complex</a>. It consists of the collection of donations, testing, processing and distribution, with ultimate transfusion to recipients at health care facilities. Along with “getting blood from donor to recipient,” ample supplies are needed for collection, testing and transfusion.</p>
<p>Less well recognized, but of immense importance, is the labor required in this supply chain, which, along with the donors, serves as the backbone. Throughout the pandemic, <a href="https://theconversation.com/the-omicron-variant-is-deepening-severe-staffing-shortages-in-medical-laboratories-across-the-us-174459">workers have been getting sick</a> from COVID-19 and many have, sadly, lost their lives. The reduction in labor availability, along with decreases in productivity, have affected supply chains from <a href="https://www.springerprofessional.de/en/perishable-food-supply-chain-networks-with-labor-in-the-covid-19/18944940">food</a> to <a href="https://doi.org/10.1016/j.ijpe.2021.108080">health care</a>.</p>
<p>With COVID-19 infection rates <a href="https://www.cnn.com/2022/01/17/health/us-coronavirus-monday/index.html">surging across the nation</a>, blood collection services are also suffering from labor shortfalls, including of <a href="https://www.opb.org/article/2021/12/20/blood-collectors-phlebotomist-shortage-red-cross-donation-oregon-washington/">blood collection specialists</a>. The Red Cross is reporting that staffing shortages in parts of the country <a href="https://www.kmvt.com/2022/01/21/local-hospitals-feeling-effects-national-blood-shortage/">are among the biggest hurdles now</a>, with higher wages being offered in this health care sector to attract workers.</p>
<p>[<em>Over 140,000 readers rely on The Conversation’s newsletters to understand the world.</em> <a href="https://memberservices.theconversation.com/newsletters/?source=inline-140ksignup">Sign up today</a>.]</p>
<p>Easing restrictions – such as <a href="https://www.tmj4.com/news/local-news/national-blood-shortage-sparks-renewed-call-to-lift-restrictions-on-gay-men-to-donate">those on gay and bisexual men</a> – could increase the availability of blood by about 2% to 4%. <a href="https://www.cbsnews.com/news/blood-shortage-gay-bisexual-men-donations-fda/">This is now being considered</a>. As we approach the third year of the pandemic, the need for blood donations and for supporting this complex supply chain is even greater than at the onset of the pandemic.</p><img src="https://counter.theconversation.com/content/175906/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Anna Nagurney does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Life-saving blood is needed for everything from treating cancers and chronic conditions to helping trauma victims. But blood donations have dropped to crisis levels during the pandemic.
Anna Nagurney, Professor and Chair in Integrative Studies, UMass Amherst
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/174770
2022-01-31T15:49:59Z
2022-01-31T15:49:59Z
How sweat sensors could play a critical role in monitoring our health
<figure><img src="https://images.theconversation.com/files/443001/original/file-20220127-22-9eyjrs.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C6000%2C3988&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sweat contains information on the condition of our bodies.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>Sweat is a biological fluid — like blood, saliva and urine — that contains metabolites, electrolytes, proteins and hormones. The levels of these vary depending on a person’s health. Wearable sweat sensors have been developed to <a href="https://doi.org/10.1007/s42242-021-00171-2">track users’ health condition and monitor the levels of these substances (known as analytes) in sweat</a>. </p>
<p>Lactate is considered an important biomarker thanks to its involvement in anaerobic metabolism. The undesired accumulation of lactate in muscles can result in fatigue, so changes in the concentration of lactate in sweat can be used to monitor fatigue. At Simon Fraser University’s Additive Manufacturing Laboratory, we have developed <a href="https://doi.org/10.1038/srep30565">a flexible sensor for sweat lactate</a>. </p>
<p>The benefit of using wearable sweat sensors is the capability for real-time, non-invasive and continuous monitoring of sweat. However, there are still challenges that must be overcome for practical biomedical applications such as diagnosis of health conditions.</p>
<h2>Sweat challenges</h2>
<p>One of the first hurdles in developing a reliable sweat sensor is the difficulty of collecting and routing of sweat. There are various methods for sampling sweat for sensing. One of the most representative approaches for collecting sweat is using <a href="https://doi.org/10.1021/acssensors.0c02446">microfluidic systems with channels that deliver sweat</a>. </p>
<p>Absorbent materials like cloth can also be <a href="https://doi.org/10.1007/s10570-019-02396-y">used for sweat sampling for sensing</a>. However, sampling sweat takes time, and how to handle the sweat sample and supply it in the sensing region in a continuous and stable manner remains a challenge for real-time measurement through continuous sensing of freshly generated sweat. </p>
<p>One of the most recent demonstrations used an <a href="https://doi.org/10.1038/s41467-020-18238-6">integrated microfluidic system with thermo-responsive hydrogels</a>. This system demonstrated significant potential for programmable control of sweat routing and sensing, which will improve the sweat handling for future sweat sensors.</p>
<p>Secondly, there is no single representative analyte in sweat. <a href="https://doi.org/10.1039/c9lc00103d">Sweat sensors can detect analytes</a> such as <a href="https://doi.org/10.1039/c9lc01045a">ammonia, ethanol</a>, ions, glucose, lactate, sweat chloride, pH, urea and creatinine, but there isn’t a single analyte that can independently provide a significant picture of an individual’s health. This means that sweat sensors must be able to measure many different substances in sweat to provide a useful report.</p>
<p>There are several sweat sensor products coming to market <a href="https://newsroom.ucla.edu/releases/adhesive-turns-smartwatch-into-biomedical-system">that measure analytes like the protein cytokine</a> and <a href="https://www.epicorebiosystems.com/">glucose and lactate</a>. </p>
<p>A third challenge is the reliability and accuracy of sweat sensors. If we measure the level of a target analyte from sweat, can we determine how reliable the result is in terms of judging the level of the same analyte in subject’s blood?</p>
<p>We still need to determine the relationship between <a href="https://doi.org/10.1039/c8lc01082j">levels of analyte in sweat and blood</a>, and <a href="https://doi.org/10.1126/sciadv.aaw9906">the relationship between sweats from different parts of body</a>. This recent study demonstrated that sweat bio-sensing can provide blood-correlated ethanol concentration data, which gives us hope that it may be possible to find blood-correlated concentrations for other analytes as well.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/443009/original/file-20220127-4399-1jj7vig.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A woman wearing a red t-shirt checks her blood glucose level" src="https://images.theconversation.com/files/443009/original/file-20220127-4399-1jj7vig.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/443009/original/file-20220127-4399-1jj7vig.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=409&fit=crop&dpr=1 600w, https://images.theconversation.com/files/443009/original/file-20220127-4399-1jj7vig.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=409&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/443009/original/file-20220127-4399-1jj7vig.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=409&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/443009/original/file-20220127-4399-1jj7vig.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=514&fit=crop&dpr=1 754w, https://images.theconversation.com/files/443009/original/file-20220127-4399-1jj7vig.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=514&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/443009/original/file-20220127-4399-1jj7vig.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=514&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">People living with diseases like diabetes can benefit from non-invasive and real-time monitoring.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<h2>Powerful solutions</h2>
<p>Users can specifically monitor targeted analytes in real-time by non-invasive sweat sensing. This can save time, energy and resources by helping people avoid painful and inconvenient invasive tests, improving health and living standards, and receiving medical assistance in a timely manner. </p>
<p>Wearable sweat sensors are a powerful solution for monitoring daily health, and could support the prevention, diagnosis, treatment and prognosis of diseases. Technological applications may come earlier than we expected through close collaboration between clinical doctors, scientists and engineers.</p><img src="https://counter.theconversation.com/content/174770/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dr. Woo Soo Kim at Simon Fraser University received funding from Natural Sciences and Engineering Research Council of Canada (NSERC). </span></em></p><p class="fine-print"><em><span>Taeil Kim does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Sensors that measure sweat could be coming to the market soon, but for them to be useful, we’ll need to understand more about this fluid that our body produces.
Woo Soo Kim, Associate Professor, Mechatronic Systems Engineering, Simon Fraser University
Taeil Kim, Postdoctoral fellow, Applied Sciences, Simon Fraser University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/174581
2022-01-31T13:00:06Z
2022-01-31T13:00:06Z
Why do we bleed? A hematologist explains how the body prevents blood loss after injury
<figure><img src="https://images.theconversation.com/files/441609/original/file-20220119-25-1kfjasu.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2039%2C1471&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The body starts plugging up wounds as quickly as it can to prevent blood loss and infection.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/finger-with-a-bead-of-blood-royalty-free-image/545247995"> Jonathan Knowles/Stone via Getty Images</a></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
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</figure>
<p><em><a href="https://theconversation.com/us/topics/curious-kids-us-74795">Curious Kids</a> is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">curiouskidsus@theconversation.com</a>.</em></p>
<hr>
<blockquote>
<p><strong>Why do we bleed? – Michael, age 9, Seattle, Washington</strong></p>
</blockquote>
<hr>
<p>“Ouch!” I cried out, looking down at where my family’s puppy, Hercules, had just bitten me. Two tiny dots of red started to bloom where he had sunk his canine teeth into my finger.</p>
<p>“Bad dog,” I said to him. He looked up at me sheepishly. “Well, I guess I’m a bad human for putting my finger near your mouth,” I admitted. He wagged his tail and licked my arm.</p>
<p>I put pressure on my finger until the bleeding stopped. Three weeks later the area had healed, and we had taught Hercules to heel, too!</p>
<p><a href="https://scholar.google.com/citations?user=n2R5Ow4AAAAJ&hl=en">I am a doctor</a> who specializes in <a href="https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/hematology">hematology</a> – the study of blood. Here, I’ll share with you how blood travels through the body, how we bleed and, more importantly, how we stop bleeding.</p>
<h2>What’s inside blood?</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/441790/original/file-20220120-9299-1mqm0vp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Diagram showing normal blood composition" src="https://images.theconversation.com/files/441790/original/file-20220120-9299-1mqm0vp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/441790/original/file-20220120-9299-1mqm0vp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=731&fit=crop&dpr=1 600w, https://images.theconversation.com/files/441790/original/file-20220120-9299-1mqm0vp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=731&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/441790/original/file-20220120-9299-1mqm0vp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=731&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/441790/original/file-20220120-9299-1mqm0vp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=919&fit=crop&dpr=1 754w, https://images.theconversation.com/files/441790/original/file-20220120-9299-1mqm0vp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=919&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/441790/original/file-20220120-9299-1mqm0vp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=919&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Blood is a mix of red and white blood cells, platelets and plasma.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:1901_Composition_of_Blood.jpg">OpenStax College/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>The blood in our bodies is a <a href="https://training.seer.cancer.gov/leukemia/anatomy/composition.html">complex fluid</a>. It contains red blood cells, which bring oxygen to our body’s tissues; white blood cells, our body’s infection-fighting army; and platelets, which clump together to help stop bleeding. A special protein called <a href="https://kidshealth.org/en/kids/blood.html">hemoglobin</a> in red blood cells is what gives our blood its beautiful red color.</p>
<p>The yellowy, liquid portion of blood is called <a href="https://www.redcrossblood.org/donate-blood/dlp/plasma-information.html">plasma</a>. Most of it – <a href="https://www.britannica.com/science/plasma-biology">over 90% of it</a> – is water, but the remaining portion contains molecules that help our blood clot and stop bleeding.</p>
<h2>Where does blood live and where does it travel?</h2>
<p>The <a href="https://emedicine.medscape.com/article/1968326-overview">bone marrow</a>, located in the center of our bones, is the factory that makes the cells circulating in our bloodstream.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/1Qfmkd6C8u8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Bone marrow transplants are given to patients with blood cancers like leukemia and lymphoma.</span></figcaption>
</figure>
<p>Once blood cells are made, they move into <a href="https://www.ncbi.nlm.nih.gov/books/NBK279250/">blood vessels</a> – rubbery tubes that form roads traveling through our entire body. Veins are the vessels that carry blood to the heart, while arteries carry blood to the rest of the body. The biggest vessels can be the width of a garden hose, while the smallest can be tinier than a human hair. Blood <a href="https://www.pbs.org/wgbh/nova/heart/heartfacts.html">travels 12,000 miles</a> through the vessels of an adult every single day!</p>
<p>The heart is the powerful engine that pushes blood through those tubes to deliver oxygen and nutrients to our organs and skin. First, the right side of the heart pumps the blood into the lungs, which contains oxygen from the air we breathe. Here, the <a href="https://doi.org/10.1002/cphy.c080113">hemoglobin</a> in red blood cells grabs oxygen and take it back to the heart. </p>
<p>The left side of the heart then pumps that oxygen-rich blood to the rest of the body. After red blood cells drop off their oxygen cargo, they are pumped back to the right side of the heart to get more oxygen and repeat their tour of the body again. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/441612/original/file-20220119-15-h5wzp6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Diagram of human circulatory system" src="https://images.theconversation.com/files/441612/original/file-20220119-15-h5wzp6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/441612/original/file-20220119-15-h5wzp6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/441612/original/file-20220119-15-h5wzp6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/441612/original/file-20220119-15-h5wzp6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/441612/original/file-20220119-15-h5wzp6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/441612/original/file-20220119-15-h5wzp6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/441612/original/file-20220119-15-h5wzp6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Blood delivers oxygen to the body by flowing through the circulatory system using a system of vessels.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/flat-design-circulatory-system-infographic-royalty-free-illustration/1286314341">Nadezhda Ivanova/iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<h2>Why do we bleed?</h2>
<p>The skin forms a protective layer over our bodies. When that layer is damaged, the blood vessels immediately underneath it are torn, allowing blood to leak out. </p>
<p>A small cut tears just the small vessels near the skin, and only a tiny amount of blood drips out. A deep cut might tear larger vessels and cause more bleeding. When we bang an arm or a leg, tearing the smaller vessels without damaging our skin, blood collects under the unbroken skin to form a <a href="https://medlineplus.gov/bruises.html">bruise</a>.</p>
<p>Because the heart is still pumping blood throughout the body, more blood will continue to leak out until the damage is patched up. To stop the leaking, a torn blood vessel releases chemicals that <a href="https://doi.org/10.1161/01.ATV.0000130465.23430.74">activate proteins</a> that clump together and form a plug to <a href="https://medlineplus.gov/ency/imagepages/19462.htm">fill the hole</a>. This seals up the blood vessel and prevents more blood from getting out. You’ve seen the results of this on your skin before: the scab that forms on top of a scrape or cut.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/441613/original/file-20220119-23-1hvgipb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Diagram showing process of platelet and fibrin clumping to close a wound to a blood vessel." src="https://images.theconversation.com/files/441613/original/file-20220119-23-1hvgipb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/441613/original/file-20220119-23-1hvgipb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=652&fit=crop&dpr=1 600w, https://images.theconversation.com/files/441613/original/file-20220119-23-1hvgipb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=652&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/441613/original/file-20220119-23-1hvgipb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=652&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/441613/original/file-20220119-23-1hvgipb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=819&fit=crop&dpr=1 754w, https://images.theconversation.com/files/441613/original/file-20220119-23-1hvgipb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=819&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/441613/original/file-20220119-23-1hvgipb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=819&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Platelets and proteins called fibrin plug the hole in a blood vessel to stop bleeding.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/hemostasis-basic-steps-of-wound-healing-royalty-free-illustration/1179785857">ttsz/iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<p>Applying pressure to a wound helps stop bleeding because it pushes the walls of the vessel together to slow the flow of blood. This helps form a clot to plug the tear, starting the healing process.</p>
<hr>
<p><em>Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to <a href="mailto:curiouskidsus@theconversation.com">CuriousKidsUS@theconversation.com</a>. Please tell us your name, age and the city where you live.</em></p>
<p><em>And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.</em></p><img src="https://counter.theconversation.com/content/174581/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mikkael A. Sekeres does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Blood plays a vital role in keeping us alive, from delivering oxygen to the body’s organs to fighting off infections.
Mikkael A. Sekeres, Professor of Medicine and Chief, Division of Hematology, Sylvester Cancer Center, University of Miami
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/158812
2021-04-14T13:46:11Z
2021-04-14T13:46:11Z
What is capillary leak syndrome and is it linked to the AstraZeneca vaccine?
<figure><img src="https://images.theconversation.com/files/395041/original/file-20210414-13-y5ib5v.jpg?ixlib=rb-1.1.0&rect=263%2C30%2C3433%2C1949&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Capillaries are the body's smallest blood vessels, and allow oxygen, nutrients and waste products to be delivered and removed from tissues.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/system-many-small-capillaries-branch-out-1748988446">hareluya/Shutterstock</a></span></figcaption></figure><p>Following the <a href="https://www.ema.europa.eu/en/news/astrazenecas-covid-19-vaccine-ema-finds-possible-link-very-rare-cases-unusual-blood-clots-low-blood">announcement</a> of a possible link between the AstraZeneca vaccine and rare blood clots, the European Medicines Agency (EMA) is now investigating whether the vaccine is linked to a second very rare blood disorder: systemic capillary leak syndrome (SCLS). </p>
<p>To date, <a href="https://www.ema.europa.eu/en/news/meeting-highlights-pharmacovigilance-risk-assessment-committee-prac-6-9-april-2021">five cases</a> of SCLS in recently vaccinated people have been reported to the EMA. The regulator’s Pharmacovigilance Risk Assessment Committee is now working to see if a causal link with the AstraZeneca vaccine can be established – as it did following reports of blood clots – and whether new safety guidelines for the vaccine are needed.</p>
<p>This investigation is a response to what the EMA calls a “safety signal”. These are unusual events that have been flagged up as possible side-effects of a given medicine, but which need researching in-depth for this to be confirmed. </p>
<p>As the <a href="https://www.ema.europa.eu/en/human-regulatory/post-authorisation/pharmacovigilance/signal-management">EMA notes</a>, receiving safety signals doesn’t itself prove that a medicine causes the adverse events being reported – illness or other medicines could also be the cause. This is why every case needs to be thoroughly investigated, and we should avoid jumping to conclusions. </p>
<p>However, with tens of millions of vaccines having been given, it’s very difficult to tease out whether such rare events can be attributed to the vaccine or are appearing as part of the normal course of events in a population.</p>
<h2>A mysterious condition</h2>
<p>We also don’t know a lot about SCLS in the first place. There have been <a href="https://rarediseases.org/rare-diseases/systemic-capillary-leak-syndrome/">fewer than 500 cases reported</a> since it was first described by researchers in 1960 (it is also known as Clarkson’s disease, after one of these scientists). </p>
<p>In this disorder, the blood plasma, the yellowish liquid part of the blood, leaks out from the smallest blood vessels, the capillaries, into the surrounding tissues, potentially causing great damage. It can lead to organ failure and death if untreated.</p>
<p>Sufferers have irregular episodes that are different in their intensity depending on the individual. This means that making a diagnosis can be difficult. Sufferers may also feel tired and have <a href="https://www.nhs.uk/conditions/oedema/">water retention</a> (also known as oedema, where fluid builds up in the body), both of which are relatively common – particularly in the elderly – and may be caused by many things. This can delay people reporting such symptoms to their GP. </p>
<figure class="align-center ">
<img alt="A patient with water retention (oedema) in one of their hands" src="https://images.theconversation.com/files/395043/original/file-20210414-21-s6llzm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/395043/original/file-20210414-21-s6llzm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=510&fit=crop&dpr=1 600w, https://images.theconversation.com/files/395043/original/file-20210414-21-s6llzm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=510&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/395043/original/file-20210414-21-s6llzm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=510&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/395043/original/file-20210414-21-s6llzm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=640&fit=crop&dpr=1 754w, https://images.theconversation.com/files/395043/original/file-20210414-21-s6llzm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=640&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/395043/original/file-20210414-21-s6llzm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=640&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Water retention can cause parts of the body to swell as fluid builds up.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/comparison-normal-right-hand-left-swollen-1395702005">Zay Nyi Nyi/Shutterstock</a></span>
</figcaption>
</figure>
<p>Unsurprisingly, SCLS can be misdiagnosed. Its symptoms are similar to those seen in sepsis, which also <a href="https://pubmed.ncbi.nlm.nih.gov/12803259/">causes the capillaries to leak</a>. SCLS also <a href="https://rarediseases.info.nih.gov/diseases/1084/systemic-capillary-leak-syndrome">causes</a> low blood pressure, low levels of albumin (a protein found in the blood plasma) and a high red blood cell concentration – all signs of other, more common disorders. </p>
<p>Together, these factors may have led to cases of the condition being missed in the past, which in turn may have hampered efforts to understand it better. It’s also plausible that they might make it harder for people to spot instances of SCLS now. However, this may be counterbalanced by the fact that people are now <a href="https://www.theguardian.com/society/2021/apr/09/ae-swamped-with-patients-seeking-help-for-mild-covid-jab-side-effects">highly alert</a> to the possibility of vaccine side-effects, and so may be more vigilant in picking them up – a recognised phenomenon known as “<a href="https://journals.sagepub.com/doi/abs/10.1177/0018578719882323">notoriety bias</a>”.</p>
<p>There’s also a common feature of SCLS that could be useful for identification: the production of an abnormal immune protein, known as M protein. This <a href="https://www.jacionline.org/article/S0091-6749(16)32460-5/pdf">occurs in up to 85%</a> of patients who are diagnosed with the condition. However, the production of M protein also occurs in some types of blood cancer, such as <a href="https://www.cancer.net/cancer-types/multiple-myeloma/stages">myeloma</a>, a much more common disease among the elderly (who have predominantly taken the vaccine).</p>
<h2>What do we know about its causes?</h2>
<p>Studies show that during SCLS there seem to be changes in the <a href="https://pubmed.ncbi.nlm.nih.gov/11591575/">integrity of blood vessel walls</a>, accompanied by a disordered immune response. It’s possible therefore that the immune system is directly affecting the blood vessels; we know from another condition – <a href="https://www.nhs.uk/conditions/vasculitis/">vasculitis</a> – that an autoimmune reaction to the blood vessels can happen.</p>
<p>Patients who have been diagnosed with SCLS tend to be <a href="https://rarediseases.org/rare-diseases/systemic-capillary-leak-syndrome/">carefully given fluids</a> to manage their symptoms, and some patients have improved after <a href="https://www.amjmed.com/article/S0002-9343(17)30602-2/pdf">being given intravenous immunoglobulin</a> (the protein from which antibodies are made). This seems to prevent further episodes, highlighting the immune system’s likely role in the disease. But the specific causes of SCLS are <a href="https://rarediseases.info.nih.gov/diseases/1084/systemic-capillary-leak-syndrome">unknown</a>.</p>
<p>The EMA will be looking closely at whether a possible mechanism is the AstraZeneca vaccine causing the immune system to attack blood vessels. A single similar incidence of this was <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4690641/">reported in 2015</a>, when a dialysis patient developed SCLS after an influenza vaccine. Although researchers were unable to link this occurrence of SCLS to the vaccine, they nevertheless reported it to the Netherlands Pharmacovigilance Centre as a possible side-effect.</p>
<p>Another question for the EMA is whether this rare blood disorder can be linked to the <a href="https://theconversation.com/blood-clot-risks-comparing-the-astrazeneca-vaccine-and-the-contraceptive-pill-158652">other recently reported safety signal</a>: blood clots with low platelet counts. While it may be tempting to link the two conditions with each other and the vaccine rollout, there’s no evidence yet to suggest they are connected. Even if both disorders are proven to be linked to the vaccine, they could still be completely unconnected. </p>
<p>It’s important to remember that there have been very few cases of this syndrome reported so far. If the regulators do establish that there’s a causal relationship between SCLS and the vaccine, the benefits of taking it still need to be weighed correctly against the risks, with this being reflected in any future guidance and communications.</p><img src="https://counter.theconversation.com/content/158812/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Peter Abel does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
European regulators are investigating a possible link between the vaccine and a second rare blood disorder.
Peter Abel, Senior Lecturer in Haematology, Immunolgy, Genetics and Evolution, University of Central Lancashire
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/151586
2021-01-20T05:33:29Z
2021-01-20T05:33:29Z
Curious Kids: how do scabs form?
<figure><img src="https://images.theconversation.com/files/379651/original/file-20210120-17-1osee28.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4368%2C2903&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p><strong>How do scabs form? — Talila, aged 8</strong></p>
<p><a href="https://theconversation.com/au/topics/curious-kids-36782"><img src="https://images.theconversation.com/files/291898/original/file-20190911-190031-enlxbk.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=90&fit=crop&dpr=1" width="100%"></a></p>
<p>Great question, Talila! </p>
<p>Our skin has many different jobs. One is to act as a barrier, protecting us from harmful things in the outside world. </p>
<p>Sometimes when we cut or graze ourselves, we tear away some layers of our skin. When the skin is damaged, it can’t do its job of protecting us quite as well. What’s underneath the skin, called tissue, can be left exposed, and germs and other nasty things may get in.</p>
<p>So when we get a cut or a graze, it’s a race against time for our bodies to stop any bleeding, protect the area, and start the repair process. And this is where scabs come in.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-how-do-wounds-heal-118603">Curious Kids: how do wounds heal?</a>
</strong>
</em>
</p>
<hr>
<h2>What happens when you cut yourself?</h2>
<p>To understand how this all works, let’s look at what would happen if you were to, say, graze the skin on your knee. You’ve probably done it before!</p>
<p>When you graze or cut yourself, blood vessels near the wound burst, causing you to bleed (blood vessels are the tubes which transport blood around your body).</p>
<p>Usually, if the wound isn’t too serious, it won’t be long before the bleeding stops. That’s because fortunately, our bodies have some clever ways of healing themselves.</p>
<figure class="align-center ">
<img alt="A girl with a bandage on her forearm." src="https://images.theconversation.com/files/379652/original/file-20210120-21-15jp5g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/379652/original/file-20210120-21-15jp5g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/379652/original/file-20210120-21-15jp5g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/379652/original/file-20210120-21-15jp5g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/379652/original/file-20210120-21-15jp5g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/379652/original/file-20210120-21-15jp5g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/379652/original/file-20210120-21-15jp5g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">There’s a lot happening under that bandage: your body is working to heal itself.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>After you cut yourself, any damaged blood vessels quickly contract, closing some of their openings so that less blood flows out.</p>
<p>Next, tiny cells in your blood called “<a href="https://pubmed.ncbi.nlm.nih.gov/16799372">platelets</a>” kick into gear. These platelets start to stick together, making a sort of plug that helps stop the bleeding and seal the cut. Other good guys in your blood also <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3428147">step in to help</a>, working with the platelets to make the plug stronger. </p>
<p>Something called a “clot” then forms. This can block the damaged blood vessels completely for some time, giving the body a chance to start the healing process for both the skin and the vessels.</p>
<p>White blood cells, which help our bodies fight infections and diseases, also <a href="https://www.ncbi.nlm.nih.gov/books/NBK554402">move into</a> the damaged area. These cells work to kill any invading bad guys that may have entered your body through the wound, and help clean up the area.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-why-do-our-toes-and-fingers-get-wrinkly-in-the-bath-120229">Curious Kids: why do our toes and fingers get wrinkly in the bath?</a>
</strong>
</em>
</p>
<hr>
<h2>Forming the scab</h2>
<p>The clotted blood at the surface of the wound starts to <a href="https://pubmed.ncbi.nlm.nih.gov/11110286">dry out</a> and forms a hardened scab. This may happen quickly, or take a few days. </p>
<p>This scab forms a protective layer, while allowing cells to move around underneath it so they can continue repairing the skin.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/378977/original/file-20210115-19-1x8yaaw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/378977/original/file-20210115-19-1x8yaaw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=429&fit=crop&dpr=1 600w, https://images.theconversation.com/files/378977/original/file-20210115-19-1x8yaaw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=429&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/378977/original/file-20210115-19-1x8yaaw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=429&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/378977/original/file-20210115-19-1x8yaaw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=539&fit=crop&dpr=1 754w, https://images.theconversation.com/files/378977/original/file-20210115-19-1x8yaaw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=539&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/378977/original/file-20210115-19-1x8yaaw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=539&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">As part of health-care training, scabs and scars can be painted on the skin using special effects makeup. This process is called ‘moulage’.</span>
<span class="attribution"><span class="source">Christian Moro</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>If you have a scab, it’s best not to pick it or scratch it off. If you remove the scab while it’s still doing its work, you could expose the wound to the outside world, increasing the risk of infection or slowing down healing.</p>
<p>If you leave it alone, after about one to two weeks the scab will eventually fall off and reveal the new, repaired skin underneath.</p>
<p>Sometimes, depending on the type of tissue damaged or how serious the injury is, a cut to the skin can <a href="https://www.youtube.com/watch?v=T-FnAH9y1N4&feature=emb_title">leave a scar</a>. This is normal.</p>
<h2>Scabs are good</h2>
<p>So Talila, don’t worry if you have a small scab on your skin after a cut or graze. Scabs are one of the good guys; they protect your body and help your wound to heal.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-why-do-we-have-boogers-133351">Curious Kids: why do we have boogers?</a>
</strong>
</em>
</p>
<hr>
<p><em>Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to curiouskids@theconversation.edu.au</em></p><img src="https://counter.theconversation.com/content/151586/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Our bodies heal in some amazing ways. Scabs can be an important part of the healing process after we get a cut or a graze.
Christian Moro, Associate Professor of Science & Medicine, Bond University
Charlotte Phelps, PhD Student, Bond University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/152113
2021-01-06T14:20:15Z
2021-01-06T14:20:15Z
Why blood donation rules have finally been relaxed for gay and bisexual men
<figure><img src="https://images.theconversation.com/files/376977/original/file-20210104-21-1un6uw5.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C6016%2C4016&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">UK transfusion services are world-leading in being the first to take an approach based on the sexual behaviour of all donors.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/close-nurse-disinfecting-male-arm-before-510475060">Olena Yakobchuk/Shutterstock</a></span></figcaption></figure><p>It can not be underestimated just how important blood is for effective healthcare provision. Of the numerous treatments people rely on for their wellbeing, blood is critical for as many as 22 different treatments, including surgery, child-birth, emergencies, end-of-life care, and treatments for <a href="https://www.donateblood.com.au/learn#how-your-blood-is-use">various diseases</a>.</p>
<p>To meet this need, 5,000 daily donations <a href="https://www.nhsbt.nhs.uk/what-we-do/blood-services/blood-donation/">are needed</a> from blood donors in the UK. The target is achieved through a small number of generous blood donors (approximately <a href="https://www.bbc.co.uk/news/health-13748004#:%7E:text=Research%20by%20NHS%20Blood%20and,above%20the%20age%20of%2040">3-4% of the eligible population</a> donates blood at any one time). </p>
<p>But as well as retaining existing regular donors, there is an ongoing need to recruit new ones. Analysis suggests that there could be potential shortfalls in blood because of increasing demand from an ageing population and a <a href="https://pubmed.ncbi.nlm.nih.gov/20849411/">reduction in the number of young donors</a>.</p>
<p>Expanding the number of potential blood donors to groups who have historically been deferred – such as men who have sex with men (MSM) – will not only create a fairer and more inclusive blood donation system but also help to address demand. </p>
<h2>The current position: who can give blood?</h2>
<p>In an important move away from the current three-month deferral on MSM giving blood, new rules due to come into play this summer will allow MSM who have had the same partner for three months or more to give blood. MSM are currently deferred from donating blood unless they have abstained from sex for three months (down from 12 months <a href="https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/809909/sabto-donor-selection-criteria-report-2017-v2.pdf">in 2017</a>
).</p>
<p>While the UK transfusion services were the first in the world to move to a three-month deferral from 12 months, the rules have historically been perceived as unfair. People have argued that it is the behaviours that people engage in, irrespective of gender and sexuality, that should be the focus of decisions to defer potential donors.</p>
<figure class="align-center ">
<img alt="Medical blood bag from blood donation" src="https://images.theconversation.com/files/377354/original/file-20210106-15-1dxmv9f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/377354/original/file-20210106-15-1dxmv9f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/377354/original/file-20210106-15-1dxmv9f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/377354/original/file-20210106-15-1dxmv9f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/377354/original/file-20210106-15-1dxmv9f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/377354/original/file-20210106-15-1dxmv9f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/377354/original/file-20210106-15-1dxmv9f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Questions about sexual behaviour will be asked of everyone volunteering to give blood when the new rules come into force.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/blood-bag-obtained-donation-603724493">NaMo Stock/Shutterstock</a></span>
</figcaption>
</figure>
<p>Though the initial relaxation of rules, to a three-month deferral, was a big step forward, the Department of Health and Social Care requested yet more progress: a selection approach based on the sexual behaviour of donors (rather than the sex of their partner). As such, the <a href="https://www.blood.co.uk/news-and-campaigns/news-and-statements/fair-steering-group/">FAIR</a> (For the Assessment of Individual Risk) steering group was set up by the <a href="https://www.nottingham.ac.uk/edi/edi-blog/blog-039.aspx">UKFORUM</a> (which represents the four UK transfusion services). </p>
<p>With a focus on individuals’ sexual behaviour, the group’s aim was to assess risks to the safety of the blood supply. It was also tasked with identifying key questions to ask donors with the aim of making recommendations to the government about changing the rules on blood donation.</p>
<h2>System based on behaviour, not sexuality</h2>
<p>To provide evidence for a potential move to rules based on assessing sexual behaviour, the FAIR group looked at a combination of epidemiological and behavioural evidence. Epidemiologists advised on the objective risk of infection for different sexual behaviours while behavioural scientists provided advice on the perceived risk of different sexual behaviours, the frequency of those behaviours and how acceptable people might find each question on their sexual behaviour. </p>
<figure class="align-center ">
<img alt="Person in red T-shirt wearing a criss-cross plaster and a red heart symbol over it on their arm" src="https://images.theconversation.com/files/376979/original/file-20210104-21-9u491u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/376979/original/file-20210104-21-9u491u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/376979/original/file-20210104-21-9u491u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/376979/original/file-20210104-21-9u491u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/376979/original/file-20210104-21-9u491u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/376979/original/file-20210104-21-9u491u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/376979/original/file-20210104-21-9u491u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Participants in the research considered the proposed change fair, needed and unlikely to increase risk to patients.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/partial-view-patient-red-tshirt-plasters-1307440612">LightField Studios/Shutterstock</a></span>
</figcaption>
</figure>
<p>The epidemiology team was comprised of Dr Su Brailsford (chair of the FAIR Steering group), Katy Davison, Claire Reynolds and Joe Flannagan from NHS Blood and Transplant and Public Health England. Together, they considered evidence on the objective risk of blood-borne infection from different sexual behaviours, infection rates in the UK and the sexual behaviour of blood donors. </p>
<p>The behavioural science work was led by the team at the School of Psychology, University of Nottingham: myself, Dr Claire Lawrence (now at <a href="https://www.lawrencepsychadvisory.com/">Lawrence PsychAdvisory</a>), Dr Naomi Pierce and Erin Dawe-Lane (now at Kings College London). </p>
<p>We explored how often people reported engaging in a series of sexual behaviours, how accurately people felt they and others could recall their sexual behaviour, how acceptable it would be for people to be asked questions about sexual behaviour, and if asking about sexual behaviour could potentially deter donors.</p>
<p>We also looked at whether sexual behaviours are reported reliably in general, and perceptions of risk to patient safety when donors are selected based on sexual behaviour. These questions were considered among the non-donors, blood donors, MSM, donor staff and patients. </p>
<p>By gathering this data, we were able to identify a set of gender-neutral questions that were perceived as acceptable to ask, unlikely to deter donors, and were associated with both a higher objective and subjective risk of infection. </p>
<p>These questions about sexual behaviour will be asked of every person volunteering to give blood when the new rules come into force in the summer of 2021. Participants in the research also considered the proposed changes to be fair, thought they were needed and were a potential way to encourage more new donors. They were considered unlikely to increase risk to patients.</p>
<p>Evidence and <a href="https://www.blood.co.uk/news-and-campaigns/news-and-statements/fair-steering-group/">recommendations for a new approach</a> were presented to the government’s Advisory Committee on the Safety of Blood, Tissues and Organs (<a href="https://www.gov.uk/government/groups/advisory-committee-on-the-safety-of-blood-tissues-and-organs">SaBTO</a>) for evaluation on October 2020. They were subsequently accepted by the <a href="https://www.gov.uk/government/news/landmark-change-to-blood-donation-criteria">Department of Health and Social Care</a> in December 2020.</p>
<p>UK transfusion services are world-leading in being the first to take an approach based on the sexual behaviour of all donors. Other countries <a href="https://www.aabb.org/news-resources/news/article/2020/12/18/advance-study-designed-to-assess-feasibility-of-updating-msm-deferral-policy-begins-enrolling-participants">including the US</a>, <a href="https://www.blood.ca/en/about-us/media/men-who-have-sex-men/msm-research-projects">Canada</a> and New Zealand are also considering a similar shift in their rules. </p>
<p>Relaxing the rules is a major step forward towards creating a fair blood donor system for all and we are very proud of this achievement and our involvement in it. The power of the FAIR project to provide evidence to support this landmark change lay in part in combining epidemiology, behavioural science and engaging wider stakeholder groups. Other countries that wish to support similar change may also now adopt such an approach.</p><img src="https://counter.theconversation.com/content/152113/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Eamonn Ferguson receives funding from UKFORUM, NHSBT, Versus Arthritis, BBSRC, Pfizer </span></em></p>
New laws due this summer will allow gay men who have had the same partner for three months or more to give blood
Eamonn Ferguson, Professor of Health Psychology, University of Nottingham
Licensed as Creative Commons – attribution, no derivatives.