By RONI CARYN RABIN Nearly a decade ago, researchers in Boston decided to see whether older men who were not in very good shape could benefit from daily doses of testosterone. The scientists recruited several hundred volunteers and gave them the hormone or a placebo. Those taking testosterone got stronger, compared with those taking the placebo, and they could carry a load up stairs faster. But they also had nearly five times the number of cardiovascular problems, including heart attacks and strokes, and safety monitors ended the trial early. Since those findings were published in 2010, studies of testosterone treatment have produced mixed results. A 2012 study of veterans aged 40 and over with low testosterone found that those treated with the hormone were less likely to die, but more recent reports, including one published last week, have documented an increase in cardiovascular risk in men over age 65 taking testosterone, as well as in younger men with a history of heart disease. Officials at the Food and Drug Administration said on Friday that they were reassessing the safety of testosterone products in light of the recent studies, and will investigate rates of stroke, heart attack and death in men using the drugs. In recent years, testosterone has been heavily promoted as a cure-all for low energy, low libido, depression and other ills among middle-aged men. “Low T” is a ubiquitous diagnosis, heard in television commercials and locker rooms. Between 2001 and 2011, hormone use by men 40 and over nearly quadrupled. By the end of that period, nearly one in 25 men in their 60s was taking testosterone. Though the drug is indicated for men with abnormally low testosterone levels, a condition called hypogonadism, doctors have been prescribing it to many men with normal levels. © 2014 The New York Times Company

Keyword: Hormones & Behavior; Sexual Behavior
Link ID: 19199 - Posted: 02.04.2014

Alice Roberts Just how special do you think you are? How different do you think you are from other animals? Do you think of yourself as an animal or do you see yourself, and your fellow humans, as somehow set apart from the rest of the animal kingdom? Most of us – and I would unashamedly label us as the sensible majority of the population – accept that evolution is the best explanation for the pattern of life that we observe on the planet, both living and fossilised. However much creationists bang on about evolution being "just a theory", it beautifully explains all the evidence we have to hand (and there's masses of that: anatomical, genetic, palaeontological, embryological), without a single piece of evidence having turned up that threatens to bring the whole edifice tumbling down around our ears. So, I'm hoping you're a sensible sort of person and that you consider evolution to be as true as the spherical nature of the Earth, or the fact that the Earth orbits the sun and not vice versa. But just how comfortable are you with the idea of being a product of evolution? I think it's still, even among the most enlightened of us, really hard to come to terms with the idea that we are just another animal. A naked ape. The third chimpanzee, even. You have to admit, science has done a very good job at bringing us down a peg or two, at knocking us off the pedestal of our own construction. We can no longer view ourselves as a special creation, something created in the image of a deity and close to angels (whatever they are or look like). We can no longer see ourselves as the ultimate destination, as the pinnacle of evolution, either. Our species is just a tiny twig on the massive, dense tree of life. But that's so difficult to stomach! © 2014 Guardian News and Media Limited

Keyword: Emotions; Evolution
Link ID: 19198 - Posted: 02.04.2014

By ABIGAIL ZUGER, M.D. In history’s long parade of pushy mothers and miserably obedient children, no episode beats Dr. Frank H. Netter’s for a happy ending. Both parties got the last laugh. Netter was born to immigrant parents in New York in 1906. He was an artist from the time he could grab a pencil, doodling through high school, winning a scholarship to art school, and enunciating intentions of making his living as an illustrator. Then his mother stepped in, and with an iron hand, deflected him to medicine. Frank’s siblings and cousins all had respectable careers, she informed him, and he would, too. To his credit, he lasted quite a while: through medical school, hospital training and almost an entire year as a qualified doctor. But he continued drawing the whole time, making sketches in his lecture notes to clarify abstruse medical concepts for himself, then doing the same for classmates and even professors. Then, fatefully, his work attracted the notice of advertising departments at pharmaceutical companies. In the midst of the Depression, he demanded and received $7,500 for a series of five drawings, many times what he might expect to earn from a full year of medical practice. He put down his scalpel for good. Thanks to a five-decade exclusive contract with Ciba (now Novartis), he ultimately became possibly the best-known medical illustrator in the world, creating thousands of watercolor plates depicting every aspect of 20th-century medicine. His illustrations were virtually never used to market specific products, but distributed free of charge to doctors as a public service, and collected into popular textbooks. © 2014 The New York Times Company

Keyword: Brain imaging
Link ID: 19197 - Posted: 02.04.2014

by Aviva Rutkin "He moistened his lips uneasily." It sounds like a cheap romance novel, but this line is actually lifted from quite a different type of prose: a neuroscience study. Along with other sentences, including "Have you got enough blankets?" and "And what eyes they were", it was used to build the first map of how the brain processes the building blocks of speech – distinct units of sound known as phonemes. The map reveals that the brain devotes distinct areas to processing different types of phonemes. It might one day help efforts to read off what someone is hearing from a brain scan. "If you could see the brain of someone who is listening to speech, there is a rapid activation of different areas, each responding specifically to a particular feature the speaker is producing," says Nima Mesgarani, an electrical engineer at Columbia University in New York City. Snakes on a brain To build the map, Mesgarani's team turned to a group of volunteers who already had electrodes implanted in their brains as part of an unrelated treatment for epilepsy. The invasive electrodes sit directly on the surface of the brain, providing a unique and detailed view of neural activity. The researchers got the volunteers to listen to hundreds of snippets of speech taken from a database designed to provide an efficient way to cycle through a wide variety of phonemes, while monitoring the signals from the electrodes. As well as those already mentioned, sentences ran the gamut from "It had gone like clockwork" to "Junior, what on Earth's the matter with you?" to "Nobody likes snakes". © Copyright Reed Business Information Ltd.

Keyword: Language; Brain imaging
Link ID: 19196 - Posted: 02.01.2014

by Laura Sanders Despite seeming like a bystander, your baby is attuned to your social life (assuming you have one, which, with a baby, would be amazing). Every time you interact with someone, your wee babe is watching, eagerly slurping up social conventions. Scientists already know that babies expect some social graces: They expect people in a conversation to look at each other and talk to other people, not objects, and are eager to see good guys rewarded and bad guys punished, scientists have found. Now, a new study shows that babies are also attuned to other people’s relationships, even when those relationships have nothing to do with them. Babies are pretty good at figuring out who they want to interact with. The answer in most cases: Nice people. And that makes sense. The helpless wailers need someone reliable around to feed, change and entertain them. So to find out how good babies are at reading other people’s social relationships, University of Chicago psychologists showed 64 9-month-old babies a video of two women eating. Sometimes the women ate from the same bowl and agreed that the food was delicious, or agreed that it was gross. Sometimes the women disagreed. Later, the women interacted again, either warmly greeting each other and smiling, or giving each other the cold shoulder, arms crossed with a “hmph.” Researchers then timed how long the babies spent looking at this last scene, with the idea that the longer the baby spent looking, the more surprising the scene was. © Society for Science & the Public 2000 - 2014.

Keyword: Development of the Brain; Emotions
Link ID: 19195 - Posted: 02.01.2014

By Molly Sharlach Reader, be proud. You’re a perceptual expert. As you read, your eyes alternately focus and move along each line of text in a seamless sequence honed over years of practice. Reading, recognizing faces and distinguishing colors or musical tones are all forms of perceptual expertise. To appreciate the visual skill involved in reading, turn a text upside down. You’ll stumble along in fits and starts, your eyes pausing longer and more often, each movement bringing less information to your brain. To assess how such neuro-ocular blundering might be improved, researchers at the University of British Columbia asked seven volunteers to practice reading novels upside down. After 30 half-hour sessions over a period of 10 weeks, they gained an average of 35 words per minute in reading speed on inverted text. This could be promising news for people with right hemianopia (hemi-uh-NOH-pee-uh), a condition that erases part of the right field of vision in both eyes. Any damage to the left occipital lobe of the brain, or the pathways connecting it to the eyes, can cause this disorder. Hemianopia, from the Greek for “half sight,” most often results from a stroke, but can also befall patients with multiple sclerosis, brain tumors or traumatic injuries. When we read, we see only three or four letters to the left of our eyes’ fixation point, but we pick up information 10 to 15 letters to the right. So in a society that reads from left to right, left hemianopia has little effect on reading ability, but right hemianopia can be devastating. Brain injury patients rank the inability to read among the most significant effects on their quality of life. © 2014 Scientific America

Keyword: Vision; Attention
Link ID: 19194 - Posted: 02.01.2014

By James Gallagher Health and science reporter, BBC News Cells taken from the donated eyes of dead people may be able to give sight to the blind, researchers suggest. Tests in rats, reported in Stem Cells Translational Medicine, showed the human cells could restore some vision to completely blind rats. The team at University College London said similar results in humans would improve quality of life, but would not give enough vision to read. Human trials should begin within three years. Donated corneas are already used to improve some people's sight, but the team at the Institute for Ophthalmology, at UCL, extracted a special kind of cell from the back of the eye. These Muller glia cells are a type of adult stem cell capable of transforming into the specialised cells in the back of the eye and may be useful for treating a wide range of sight disorders. In the laboratory, these cells were chemically charmed into becoming rod cells which detect light in the retina. Injecting the rods into the backs of the eyes of completely blind rats partially restored their vision. Brain scans showed that 50% of the electrical signals between the eye and the brain were recovered by the treatment. One of the researchers, Prof Astrid Limb, told the BBC what such a change would mean in people: "They probably wouldn't be able to read, but they could move around and detect a table in a room. BBC © 2014

Keyword: Vision; Glia
Link ID: 19193 - Posted: 02.01.2014

By LAUREN BRADY When I was 18 I watched my father perform what would be his final surgery. It was the summer of 2007 and I had just returned to Colorado after surviving my freshman year of film school at New York University. One day my dad invited me to observe a vitrectomy. And while I hadn’t a clue what this would entail I immediately accepted, honored by the invitation and determined not to faint. My father’s 21 years as an ophthalmologist produced over 15,000 operations, a private practice spanning three offices, and very little vacation time. While I sensed from an early age that the long hours were taxing on him I never felt an absence. In fact, my childhood was picturesque: two loving parents, a rowdy little brother whom I pushed around until he was big enough to push back, family trips in the Jeep to the Rocky Mountains. He was the dad with the Handycam at every soccer game and school play. He worked as a surgeon, but he lived for his children. The morning of the vitrectomy we left extra early because of a limp in my dad’s right leg that had appeared a few months earlier and had gradually worsened. He suspected it was a pinched nerve and had been meaning to get it checked out. In the interim, he had started using a chair during surgery. Walking toward the hospital entrance we encountered a fellow doctor who greeted me with the familiarity of someone who’d been exposed to years of my father’s wallet photos. He asked how I liked Greenwich Village, whether I had directed any films yet and if I had tried a bialy. We walked and talked until I noticed at one point that my dad was no longer part of the conversation. Turning around I realized he was a half block back pushing himself up from the ground. © 2014 The New York Times Company

Keyword: ALS-Lou Gehrig's Disease
Link ID: 19192 - Posted: 02.01.2014

By Jennifer Ouellette It was a brisk October day in a Greenwich Village café when New York University neuroscientist David Poeppel crushed my dream of writing the definitive book on the science of the self. I had naively thought I could take a light-hearted romp through genotyping, brain scans, and a few personality tests and explain how a fully conscious unique individual emerges from the genetic primordial ooze. Instead, I found myself scrambling to navigate bumpy empirical ground that was constantly shifting beneath my feet. How could a humble science writer possibly make sense of something so elusively complex when the world’s most brilliant thinkers are still grappling with this marvelous integration that makes us us? “You can’t. Why should you?” Poeppel asked bluntly when I poured out my woes. “We work for years and years on seemingly simple problems, so why should a very complicated problem yield an intuition? It’s not going to happen that way. You’re not going to find the answer.” Well, he was right. Darn it. But while I might not have found the Ultimate Answer to the source of the self, it proved to be an exciting journey and I learned some fascinating things along the way. 1. Genes are deterministic but they are not destiny. Except for earwax consistency. My earwax is my destiny. We tend to think of our genome as following a “one gene for one trait” model, but the real story is far more complicated. True, there is one gene that codes for a protein that determines whether you will have wet or dry earwax, but most genes serve many more than one function and do not act alone. Height is a simple trait that is almost entirely hereditary, but there is no single gene helpfully labeled height. Rather, there are several genes interacting with one another that determine how tall we will be. Ditto for eye color. It’s even more complicated for personality traits, health risk factors, and behaviors, where traits are influenced, to varying degrees, by parenting, peer pressure, cultural influences, unique life experiences, and even the hormones churning around us as we develop in the womb.

Keyword: Brain imaging; Genes & Behavior
Link ID: 19191 - Posted: 02.01.2014

Madhusree Mukerjee By displaying images on an iPad, researchers tested patients' ability to detect contrast after their vision was restored by cataract surgery. In a study of congenitally blind children who underwent surgery to restore vision, researchers have found that the brain can still learn to use the newly acquired sense much later in life than previously thought. Healthy infants start learning to discern objects, typically by their form and colour, from the moment they open their eyes. By the time a baby is a year old vision development is more or less complete, although refinements continue through childhood. But as the brain grows older, it becomes less adaptable, neuroscientists generally believe. "The dogma is that after a certain age the brain is unable to process visual inputs it has never received before," explains cognitive scientist Amy Kalia of the Massachusetts Institute of Technology (MIT) in Cambridge. Consequently, eye surgeons in India often refuse to treat children blinded by cataracts since infancy if they are over the age of seven. Such children are not usually found in wealthier countries such as the United States — where cataracts are treated as early as possible — but are tragically plentiful in India. In the study, which was published last week in Proceedings of the National Academy of Sciences1, Kalia and her collaborators followed 11 children enrolled in Project Prakash2, a humanitarian and scientific effort in India that provides corrective surgery to children with treatable cataracts and subsequently studies their visual abilities. ('Prakash' is Sanskrit for light.) © 2014 Nature Publishing Group

Keyword: Development of the Brain; Vision
Link ID: 19190 - Posted: 01.30.2014

Controversy delights Dick Swaab; brains delight him; complexity delights him, though I don't know if you'd get that from reading his book, We Are Our Brains, in which causal links are made quite casually, like a man doing a crossword with a pencil. The Dutch neurologist is, after a 50-year career, a giant in the field. He is a professor of neurobiology at the University of Amsterdam. His directorship of the Dutch Institute for Brain Research yielded material that has been sent to 500 other research groups in 25 countries. He has propounded groundbreaking theories in his specialist area: the impact on brain development in the womb. Nonetheless, his book, despite directing itself squarely to the layperson, has been miles more successful than he thought, selling 100,000 copies ("the publishers say they knew it would be a hit. But at the start, they only printed 3,000 copies. So I know that is not true."). There are a number of lines you might file under, "Well, there's a curiosity" (for instance: "In professional violinists, the part of the cerebral cortex that directs the fingers of the left hand is five times as large as it is in people who don't play a stringed instrument"). And yet the real fireworks of the book are both more predictable and more profound: Swaab says hormones and chemical substances in utero affect the development of our sexual orientation or, put more simply, you have a gay brain by the time you are born. Male and female brains have "hundreds of differences", which explain all the ways in which men and women are different; "phobia, impulsiveness, ADHD and depression later in life" can be traced back to a mother's fearfulness during pregnancy, which activates her baby's "fear axis". © 2014 Guardian News

Keyword: Sexual Behavior
Link ID: 19189 - Posted: 01.30.2014

By Meeri Kim, Neanderthal genes lurk among us. Small traces of Neanderthal DNA have been confirmed in the areas of the genome that affect skin and hair of modern humans, according to two new studies that also give clues as to which Neanderthal traits may have been helpful — or harmful — to the survival of our species. The studies, published online Wednesday in the journals Nature and Science, came to similar conclusions despite using vastly different methods of genomic analysis. For East Asian and European populations, genes that provide the physical characteristics of skin and hair have a high incidence of Neanderthal DNA — possibly lending toughness and insulation to weather the cold as early man emerged from Africa, the studies conclude. Neanderthals were thought to have already been adapted to a chillier, more northern environment. Perhaps most notably, Neanderthal DNA was not found in genes that influence testicles or the X chromosome, according to the Nature study, hinting that when the Neanderthal ventured outside his species for sex, the introduction of his DNA may have reduced male fertility in early humans. As a result, evolution wiped away the Neanderthal DNA that negatively affected procreation. “There’s strong evidence that when the two met and mixed, they were at the edge of biological compatibility,” said Nature study author and Harvard University geneticist David Reich. “The people who eventually survived and thrived had quite a bit of hurdles to overcome.” This is consistent with what is seen in nature: When two species mate that are sufficiently far away biologically, the resulting hybrids tend to have lowered fertility. Early humans and Neanderthals interbred about 40,000 to 80,000 years ago around the Middle East, during man’s migration out of Africa. © 1996-2014 The Washington Post

Keyword: Evolution; Genes & Behavior
Link ID: 19188 - Posted: 01.30.2014

By GINA KOLATA For many obese adults, the die was cast by the time they were 5 years old. A major new study of more than 7,000 children has found that a third of children who were overweight in kindergarten were obese by eighth grade. And almost every child who was very obese remained that way. Some obese or overweight kindergartners lost their excess weight, and some children of normal weight got fat over the years. But every year, the chances that a child would slide into or out of being overweight or obese diminished. By age 11, there were few additional changes: Those who were obese or overweight stayed that way, and those whose weight was normal did not become fat. “The main message is that obesity is established very early in life, and that it basically tracks through adolescence to adulthood,” said Ruth Loos, a professor of preventive medicine at the Icahn School of Medicine at Mount Sinai in New York, who was not involved in the study. These results, surprising to many experts, arose from a rare study that tracked children’s body weight for years, from kindergarten through eighth grade. Experts say they may reshape approaches to combating the nation’s obesity epidemic, suggesting that efforts must start much earlier and focus more on the children at greatest risk. The findings, to be published Thursday in The New England Journal of Medicine, do not explain why the effect occurs. Researchers say it may be a combination of genetic predispositions to being heavy and environments that encourage overeating in those prone to it. But the results do provide a possible explanation for why efforts to help children lose weight have often had disappointing results. The steps may have aimed too broadly at all schoolchildren, rather than starting before children enrolled in kindergarten and concentrating on those who were already fat at very young ages. © 2014 The New York Times Company

Keyword: Obesity; Development of the Brain
Link ID: 19187 - Posted: 01.30.2014

by Susan Milius Male bee flies fooled into trying to copulate with a daisy may learn from the awkward incident. Certain orchids and several forms of South Africa’s Gorteria diffusa daisy lure pollinators by mimicking female insects. The most effective daisy seducers row a dark, somewhat fly-shaped bump on one of their otherwise yellow-to-orange petals. Males of small, dark Megapalpus capensis bee flies go wild. But tests show the daisy’s victims waste less time trying to mate with a second deceptive daisy than with the first. “Far from being slow and stupid, these males are actually quite keen observers and fairly perceptive for a fly,” says Marinus L. de Jager of Stellenbosch University in South Africa. Males’ success locating a female bee fly drops in the presence of deceitful daisies, de Jager and Stellenbosch University colleague Allan Ellis say January 29 in the Proceedings of the Royal Society B. That’s the first clear demonstration of sexual deceit’s cost to a pollinator, Ellis says. Such evolutionary costs might push the bee fly to learn from mating mistakes. How long bee flies stay daisy-wary remains unknown. In other studies, wasps tricked by an Australian orchid forgot their lesson after about 24 hours. © Society for Science & the Public 2000 - 2014

Keyword: Learning & Memory; Evolution
Link ID: 19186 - Posted: 01.30.2014

|By Roni Jacobson There is nothing like a good night's sleep to help you feel your best the next day. Now scientists are finding that good sleep habits may do more than restore cognitive function on a nightly basis—they may also fortify the brain over the long term, according to a new study in the Journal of Neuroscience. Researchers at the University of Wisconsin–Madison found that during sleep, activity ramps up in genes that are involved in producing oligodendrocytes—brain cells responsible for coating neurons with myelin. Myelin is the brain's insulating material. The fatty substance surrounds the signal-transmitting tail that extends from every neuron, enabling electrical communications to travel quickly and efficiently to other neurons. Myelin deficiency is at the root of the neurodegenerative disease multiple sclerosis and can contribute to symptoms such as fatigue, vision and hearing impairment, and a loss of coordination. In this study, sleeping mice had heightened activity in the genes responsible for creating oligodendrocytes, but awake or sleep-deprived rodents showed greater activity in genes involved in cellular stress and death. Chiara Cirelli, a neuroscientist and author on the paper, suggests that sleep helps cells regenerate and repair themselves, by enabling the body to produce new myelin after it has deteriorated. Cellular repair probably takes weeks or even months, however, so pulling an occasional all-nighter is unlikely to disrupt the process. © 2014 Scientific American

Keyword: Sleep
Link ID: 19185 - Posted: 01.30.2014

by Ashley Yeager Monkeys may have rudimentary brain wiring that later evolved into the connections that gave humans the ability to understand language, think flexibly and make decisions. Brain scans of 25 humans and 25 macaques show that 11 components of the ventrolateral frontal cortex, located behind the temples, were similarly wired in both species. The results suggest that humans did not develop completely new and specialized brain systems for certain types of complex thought, researchers report January 28 in Neuron. The scans also show that macaques do not have the lateral frontal pole, which helps humans with strategic planning, decision-making and multitasking. © Society for Science & the Public 2000 - 2014.

Keyword: Evolution
Link ID: 19184 - Posted: 01.30.2014

Alison Abbott By slicing up and reconstructing the brain of Henry Gustav Molaison, researchers have confirmed predictions about a patient that has already contributed more than most to neuroscience. No big scientific surprises emerge from the anatomical analysis, which was carried out by Jacopo Annese of the Brain Observatory at the University of California, San Diego, and his colleagues, and published today in Nature Communications1. But it has confirmed scientists’ deductions about the parts of the brain involved in learning and memory. “The confirmation is surely important,” says Richard Morris, who studies learning and memory at the University of Edinburgh, UK. “The patient is a classic case, and so the paper will be extensively cited.” Molaison, known in the scientific literature as patient H.M., lost his ability to store new memories in 1953 after surgeon William Scoville removed part of his brain — including a large swathe of the hippocampus — to treat his epilepsy. That provided the first conclusive evidence that the hippocampus is fundamental for memory. H.M. was studied extensively by cognitive neuroscientists during his life. After H.M. died in 2008, Annese set out to discover exactly what Scoville had excised. The surgeon had made sketches during the operation, and brain-imaging studies in the 1990s confirmed that the lesion corresponded to the sketches, although was slightly smaller. But whereas brain imaging is relatively low-resolution, Annese and his colleagues were able to carry out an analysis at the micrometre scale. © 2014 Nature Publishing Group

Keyword: Learning & Memory; Brain imaging
Link ID: 19183 - Posted: 01.29.2014

Henry Molaison, the famous amnesic patient better known as “H.M.,” was unable to form new long-term memories following brain surgery to treat his epilepsy. Scientists who studied his condition made groundbreaking discoveries that revealed how memory works, and before his 2008 death, H.M. and his guardian agreed that his brain would be donated to science. One year after his death, H.M.’s brain was sliced into 2,401 70-micron-thick sections for further study. MIT neuroscience professor emerita Suzanne Corkin studied H.M. during his life and is now part of a team that is analyzing his brain. She is an author of a paper appearing in Nature Communications today reporting preliminary results of the postmortem study. The research team was led by Jacopo Annese at the University of California at San Diego (UCSD). Q: What can we learn from studying H.M.’s brain after his death? And when did you begin laying the groundwork for these postmortem studies? A: It was important to get H.M.’s brain after he died, for three reasons: first of all, to document the exact locus and extent of his lesions, in order to identify the neural substrate for declarative memory. Second, to evaluate the status of the intact brain tissue, revealing the possible brain substrates for the many cognitive functions that H.M. performed normally, including nondeclarative learning without awareness. The third reason was to identify any new abnormalities that occurred as a result of his getting old and were unrelated to the operation. In 1992, I explained to H.M. and his conservator that it would be extremely valuable to have his brain after he died. I told them how important he was to the science of memory, and that he had already made amazing contributions. It would make those even more significant to actually have his brain and see exactly where the damage was. That year, they signed a brain donation form leaving his brain to Massachusetts General Hospital [MGH] and MIT.

Keyword: Learning & Memory
Link ID: 19182 - Posted: 01.29.2014

A food poisoning bacterium may be implicated in MS, say US researchers. Lab tests in mice by the team from Weill Cornell Medical College revealed a toxin made by a rare strain of Clostridium perfringens caused MS-like damage in the brain. And earlier work by the same team, published in PLoS ONE, identified the toxin-producing strain of C. perfringens in a young woman with MS. But experts urge caution, saying more work is needed to explore the link. No-one knows the exact cause of Multiple sclerosis (MS), but it is likely that a mixture of genetic and environmental factors play a role. It's a neurological condition which affects around 100,000 people in the UK. Most cases of human infection occur as food poisoning - diarrhoea and stomach cramps that usually resolve within a day or so. More rarely, the bacterium can cause gas gangrene. And a particular strain of C. perfringens, Type B, which the Weill team says it identified in a human for the first time, makes a toxin that can travel through blood to the brain. In their lab studies on rodents the researchers found that the toxin, called epsilon, crossed the blood-brain barrier and killed myelin-producing cells - the typical damage seen in MS. BBC © 2014

Keyword: Multiple Sclerosis; Neuroimmunology
Link ID: 19181 - Posted: 01.29.2014

Parasites don’t just cause nasty infections; they can also take over the minds of their hosts. The Ophiocordyceps fungus, for example, forces ants to climb up the stems of plants, where they die and release the fungus’s spores into the air to infect more ants. Likewise, it would make sense for sexually transmitted parasites to force their hosts to have sex more. But biologists have found very few examples of this in nature. A new study may explain why. To figure out why there isn’t more “sexual mind control” in nature, theoretical ecologist Ludek Berec, of the Biology Centre of the Academy of Sciences of the Czech Republic, and biological mathematician Daniel Maxin, of Valparaiso University in Indiana, turned to mathematical modeling. They created two strains of a hypothetical parasite species: an “ancestor” that did not make its hosts have sex more, and a mutant that did. Then they turned the two strains loose in a hypothetical host population and watched the parasites compete until the mutant strain either died out or replaced its ancestor. If the mutant strain replaced its ancestor, the researchers introduced a new mutant that had even more power over its host’s sex life. They then watched the two strains compete again, introduced yet another, stronger mutant when the old one outcompeted its predecessor, and so on. In this way, the species as a whole could “evolve” to exert more or less sexual mind control over its host. © 2014 American Association for the Advancement of Science.

Keyword: Sexual Behavior
Link ID: 19180 - Posted: 01.29.2014