I'd like to tell you a curious story. Jane was a 52 year old woman in need of a kidney transplant. Thankfully she had three loving sons who were all very happy to give her one of theirs. So Jane's doctors performed tests to find out which of the three boys would be the best match, but the results surprised everyone. In the words of Jeremy Kyle, the DNA test showed that Jane was not the mother of two of the boys... Hang on, said Jane, child birth is not something you easily forget. They're definitely mine. And she was right. It turns out Jane was a chimera. Chimerism is the existence of two genetically different cell lines in one organism. This can arise for a number of reasons- it can be iatrogenic, like when someone has an organ transplant, or it can be naturally occurring. In Jane's case, it began in her mum's womb, with two eggs that had been fertilised by different sperm creating two embryos. Ordinarily, they would develop into two non-identical twins. However in Jane's case the two balls of cells fused early in development creating one person with both cell lines. Thus when doctors did the first tissue typing tests on Jane, just by chance they had only sampled the 'yellow' cell line which was responsible for one of her sons. When they went back again they found the 'pink' cell line which had given rise to the other two boys. This particular type of human chimerism is thought to be pretty rare- there are only 30 case reports in the literature. (Though remarkably both House and CSI's Gil Grissom have encountered cases.) What happens far more frequently is fetal microchimerism- which occurs in pregnant women when cells cross the placenta from baby to mum. This is awesome because we used to think the placenta was this barrier which prevented any cells crossing over. Now we've found both cells and free floating DNA cross the placenta, and that the cells can hang around for decades after the baby was born. Why? As is often the case in medicine we're not sure but one theory is that the fetal cells might have healing properties for mum. In pregnant mice who've had a heart attack, fetal cells can travel to the mum's heart where the develop into new heart muscle to repair the damage. Whilst we're still in the early stages of understanding why this happens, we already have a practical application. In the United States today, a pregnant woman can have a blood test which isn't looking for abnormalities in her DNA but in that of her fetus. The DNA test isn't conclusive enough to be used to diagnose genetic conditions, but it is a good screening test for certain trisomies including Down's syndrome. Now, we started with a curious tale, so lets close with a curious fact, and one that's appropriate for Mother's Day: This exchange of cells across the placenta is a two way process. So you may well have some of your mum's cells rushing through your veins right now. In my case they're probably the ones that tell me to put on sensible shoes and put that boy down... (FYI: This is a story I originally posted on my own blog)
Dr Catherine Carver
over 4 years ago
The fourth edition of NMS Physiology, a well respected and heavily used text, is written in an outline format useful to medical students who require a physiology course review and a comprehensive study tool for USMLE preparation. This one-volume, portable text contains 300 USMLE-style questions with answers and explanations. New to the edition are more questions, updated case studies in clinical decision making, concise outlines, and expanded diagrams. Sections devoted to endocrinology, acid-base, and pathophysiology also are especially helpful to students.
over 2 years ago
Printed from STUDENT CONSULT: Berne and Levy Physiology 6E - The Online Medical Library for Students plus USMLE Steps 123 (ver. 2.9)
A library of electronic medical textbooks for students and instructors, with additional interactive features (questions, case studies, animations). Free chapters, questions, and animations available.
over 2 years ago
The second edition of Bedside Obstetrics & Gynecology brings postgraduate trainees fully up to date with the most recent advances in the field. The first section covers obstetrics, discussing normal and abnormal presentations (such as normal labour versus breech presentation), complications in pregnancy (including early pregnancy bleeding and ante- and postpartum haemorrhage), and medical disorders related to pregnancy (such as preeclampsia and gestational diabetes). Section two covers numerous gynaecological abnormalities. This new edition has been fully revised but continues to emphasise the importance of history taking and clinical examination. New chapters have been added to cover topics such as preterm pregnancy, post-dated pregnancy and intrauterine death, bleeding due to miscarriage, menopause and contraception. Nearly 1100 images, illustrations and tables enhance learning, and each chapter includes questions and answers related to case studies. Key points Fully revised, new edition providing recent advances in obstetrics and gynaecology Many new chapters added Includes 1100 images, illustrations and tables Previous edition published in 2010
about 2 years ago
Education in South Africa is characterised by historical inequalities that may lead to poor learning experiences and performance, especially amongst groups that experience isolation and disaffection. The perspective of alienated and engaged experiences of learning, taking into account the student’s social and cultural context may be more valuable to study than only focusing on approaches to learning. Aims of project: To determine the factors that have an impact on a student’s perceptions of engagement and alienation in the postgraduate pathology environment at Stellenbosch University. A cross-sectional case study through semi-structured interviews, investigating 17 postgraduate students in Pathology selected by purposive sampling, were undertaken, exploring aspects of alienation and engagement. Conclusion Factors can change have been identified and support systems that may impact on students’ learning experiences and throughput can be developed. With a view to addressing the intellectual capacity and health care needs in the country, it is crucial that these issues be investigated and adressed.
over 7 years ago
Platelet satellitism can easily catch you unawares, if you are not careful. In this video, the mechanisms and implication of the presence of platelet satellitism is described making use of a case study.
over 4 years ago
New case study in the Annals of Global Health assesses the immediate and ongoing response to the 9/11 disaster and explores the implications for future disastersFourteen years...
about 2 years ago
When is it medically advisable to eat some one else's poo? When you need a poo transplant. Poo transplants could be the solution to one of the biggest problems facing the NHS today- the bacterial infection Clostridium difficile. C.diff, as it's known to its friends, infects about 18,000 people in England and Wales every year and is involved in the deaths of about 2000 people. C.diff typically arises due to imbalances in the normal gut bacteria. The gut is like a city, a city with about 100 trillion bacterial residents happily munching away on a banquet of bowel contents. The average person has about 1000 different types of bacteria in their gut, and about 3% of healthy adults have C.diff in that mix. The C.diff doesn't cause them any problems because its numbers are kept in check by the other gut bacteria. However treatment with broad spectrum antibiotics such as clindamycin, cephalosporins, ciprofloxacin and co-amoxiclav, can disrupt this happy community- killing off vast swathes of bacteria but crucially not the C.diff. Given free rein the C.diff multiplies rapidly and produces toxins which damage the gut. In some people this causes mild diarrhoea and abdominal pain, in others it can lead to torrential diarrhoea, perforation of the colon and death. Traditional treatment includes stopping any broad spectrum antibiotics and possibly prescribing antibiotics which target the C.diff such as metronidazole or vancomycin. However with antibiotic use comes the risk of resistance. Moreover our current approach isn't entirely effective and about 22% of patients treated suffer a recurrence. This can result in a cycle of illness and hospital admission which is costly to the patient and the hospital. So it's time to start thinking outside of the box. Cue the poo transplant. The thinking goes like this- if the cause of the problem is disruption to the normal community of gut bacteria, why not just pop those bacteria back in to crowd out the C.diff? Simples. Practically, the first step is to identify a donor, usually a close relative of the patient, and screen them for a range of infectious diseases and parasites. It's also advisable to make sure they haven't recently consumed anything the intended recipient is allergic to, before asking them to make their "donation". You then pop it in a household blender and blitz it down, adding saline or milk to achieve a slurry consistency. Next you need to strain your concoction to remove large materials- one medic in the UK uses coffee filters. Top tip. Then you're ready to administer it- about 25ml from above (e.g. via nasogastric tube), or 250ml from below. Now, its important to note that poo transplants are still an experimental treatment. To date only small case studies have been carried out, but with 200 total reported cases, an average cure rate of 96% and no serious adverse events reported to date, it's worth carrying out a large trial to assess it thoroughly. Poo transplants- arguably the ideal treatment for a cash strapped NHS. It's cheap, plentiful and it seems to work. Now to convince people to consume someone else's poo... Bottoms up! FYI: This was first posted on my own blog. Image Courtesy of Marcus007 at de.wikipedia [Public domain], from Wikimedia Commons
Dr Catherine Carver
about 4 years ago