Chapter 13. Homeostasis: Active Regulation of the Internal Environment

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By Meredith Wadman The hallmark brain damage in Parkinson’s disease is thought to be the work of a misfolded, rogue protein that spreads from brain cell to brain cell like an infection. Now, researchers have found that the normal form of the protein—α-synuclein (αS)—may actually defend the intestines against invaders by marshaling key immune cells. But chronic intestinal infections could ultimately cause Parkinson’s, the scientists suggest, if αS migrates from overloaded nerves in the gut wall to the brain. “The gut-brain immune axis seems to be on a cusp of an explosion of new insights, and this work offers an exceptionally exciting new hypothesis,” says Charles Bevins, an expert in intestinal immunity at the University of California, Davis, who was not involved with the study. The normal function of αS has long been a mystery. Though the protein is known to accumulate in toxic clumps in the brain and the nerves of the gut wall in patients with Parkinson’s disease, no one was sure what it did in healthy people. Noting that a region of the αS molecule behaves similarly to small, microbe-targeting proteins that are part of the body’s immune defenses, Michael Zasloff, an immunologist at Georgetown University Medical Center in Washington, D.C., set out to find whether αS, too, might help fend off microbial invaders. © 2017 American Association for the Advancement of Science

Keyword: Parkinsons
Link ID: 23784 - Posted: 06.28.2017

Cassie Martin Long typecast as the strong silent type, bones are speaking up. In addition to providing structural support, the skeleton is a versatile conversationalist. Bones make hormones that chat with other organs and tissues, including the brain, kidneys and pancreas, experiments in mice have shown. “The bone, which was considered a dead organ, has really become a gland almost,” says Beate Lanske, a bone and mineral researcher at Harvard School of Dental Medicine. “There’s so much going on between bone and brain and all the other organs, it has become one of the most prominent tissues being studied at the moment.” At least four bone hormones moonlight as couriers, recent studies show, and there could be more. Scientists have only just begun to decipher what this messaging means for health. But cataloging and investigating the hormones should offer a more nuanced understanding of how the body regulates sugar, energy and fat, among other things. Of the hormones on the list of bones’ messengers — osteocalcin, sclerostin, fibroblast growth factor 23 and lipocalin 2 — the last is the latest to attract attention. Lipocalin 2, which bones unleash to stem bacterial infections, also works in the brain to control appetite, physiologist Stavroula Kousteni of Columbia University Medical Center and colleagues reported in the March 16 Nature. After mice eat, their bone-forming cells absorb nutrients and release a hormone called lipocalin 2 (LCN2) into the blood. LCN2 travels to the brain, where it gloms on to appetite-regulating nerve cells, which tell the brain to stop eating, a recent study suggests. © Society for Science & the Public 2000 - 2017.

Keyword: Hormones & Behavior
Link ID: 23762 - Posted: 06.22.2017

By GRETCHEN REYNOLDS Better grades might be found on the playground. A new study of elementary-age children shows that those who were not part of an after-school exercise program tended to pack on a particular type of body fat that can have deleterious impacts on brain health and thinking. But prevention and treatment could be as simple as playing more games of tag. Most children do not meet the federal health guidelines for exercise, which call for at least an hour of it a day for anyone under the age of 18. Physical inactivity can result in weight gain, especially around the midsection — including visceral fat, a type of tissue deep inside the abdomen that is known to increase inflammation throughout the body. It is also linked to heightened risks for diabetes and cardiovascular complications, even in children, and may contribute to declining brain function: Obese adults often perform worse than people of normal weight on tests of thinking skills. But little has been known about visceral fat and brain health in children. For a soon-to-be-published study, researchers from Northeastern University in Boston and the University of Illinois at Urbana-Champaign tracked hundreds of 8-to-10-year-old children in a nine-month after-school exercise program in Urbana. Every day, one group of children played tag and other active games for about 70 minutes. The subjects in a control group continued with their normal lives, with the promise that they could join the program the following year. All the children completed tests of fitness, body composition and cognitive skills at the start and end of the program. The researchers did not ask the children to change their diets. © 2017 The New York Times Company

Keyword: Obesity
Link ID: 23747 - Posted: 06.17.2017

By MATT RICHTEL More than 10 percent of the world’s population is now obese, a marked rise over the last 30 years that is leading to widespread health problems and millions of premature deaths, according to a new study, the most comprehensive research done on the subject. Published Monday in The New England Journal of Medicine, the study showed that the problem had swept the globe, including regions that have historically had food shortages, like Africa. The study, compiled by the Institute for Health Metrics and Evaluation at the University of Washington and funded by the Gates Foundation, looked at 195 countries, essentially the world’s population, finding that rates of obesity at least doubled in 73 countries — including Turkey, Venezuela and Bhutan — from 1980 to 2015, and “continuously increased in most other countries.” Analyzing some 1,800 data sets from around the world, researchers found that excess weight played a role in four million deaths in 2015, from heart disease, diabetes, kidney disease and other factors. The per capita death rate was up 28 percent since 1990 and, notably, 40 percent of the deaths were among people who were overweight but not heavy enough to be classified as obese. The study defined obese as a body mass index of 30 or higher and overweight as a B.M.I. from 25 to 29. By those measures, nearly 604 million adults worldwide are obese and 108 million children, the authors reported. Obesity rates among children are rising faster in many countries than among adults. In the United States, 12.5 percent of children were obese, up from 5 percent in 1980. Combining children and adults, the United States had the dubious distinction of having the largest increase in percentile points of any country, a jump of 16 percentage points to 26.5 percent of the overall population. © 2017 The New York Times Company

Keyword: Obesity
Link ID: 23734 - Posted: 06.13.2017

Children born to women with gestational diabetes whose diet included high proportions of refined grains may have a higher risk of obesity by age 7, compared to children born to women with gestational diabetes who ate low proportions of refined grains, according to results from a National Institutes of Health study. These findings, which appear online in the American Journal of Clinical Nutrition, were part of the Diabetes & Women’s Health Study, a research project led by NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). Gestational diabetes, or high blood sugar during pregnancy, affects about 5 percent of all pregnancies in the United States and may lead to health problems for mothers and newborns. The authors noted that previous studies have linked diets high in refined grains — such as white rice — to obesity, type 2 diabetes and heart disease. The researchers compared records from 918 mother-child pairs who took part in the Danish National Birth Cohort, a study that followed the pregnancies of more than 91,000 women in Denmark. They found that children born to women with gestational diabetes who consumed the most refined grain (more than 156 grams per day) were twice as likely to be obese at age 7, compared to children born to women with gestational diabetes who ate the least amount of refined grain (less than 37 grams per day). The link between maternal grain consumption during pregnancy and obesity by age 7 still persisted when the researchers controlled for factors that could potentially influence the children’s weight — such as physical activity level and consumption of vegetables, fruit and sweets. The authors called for additional studies to confirm their results and to follow children through later childhood, adolescence and adulthood to see if the obesity risk persists later in life.

Keyword: Obesity; Development of the Brain
Link ID: 23720 - Posted: 06.08.2017

Children born to women who had gestational diabetes and drank at least one artificially sweetened beverage per day during pregnancy were more likely to be overweight or obese at age 7, compared to children born to women who had gestational diabetes and drank water instead of artificially sweetened beverages, according to a study led by researchers at the National Institutes of Health. Childhood obesity is known to increase the risk for certain health problems later in life, such as diabetes, heart disease, stroke and some cancers. The study appears online in the International Journal of Epidemiology. According to the study authors, as the volume of amniotic fluid increases, pregnant women tend to increase their consumption of fluids. To avoid extra calories, many pregnant women replace sugar-sweetened soft drinks and juices with beverages containing artificial sweeteners. Citing prior research implicating artificially sweetened beverages in weight gain, the study authors sought to determine if diet beverage consumption during pregnancy could influence the weight of children. “Our findings suggest that artificially sweetened beverages during pregnancy are not likely to be any better at reducing the risk for later childhood obesity than sugar-sweetened beverages,” said the study’s senior author, Cuilin Zhang, Ph.D., in the Epidemiology Branch at NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). “Not surprisingly, we also observed that children born to women who drank water instead of sweetened beverages were less likely to be obese by age 7.”

Keyword: Obesity; Development of the Brain
Link ID: 23717 - Posted: 06.07.2017

By JANE E. BRODY Harding Senior High, a public school in St. Paul, Minn., has long been known as a 90-90-90 school: 90 percent of students are minorities, nearly 90 percent come from poor or struggling families and, until recently, 90 percent graduate (now about 80 percent) to go on to college or a career. Impressive statistics, to be sure. But perhaps most amazing about this school is that it recognizes and acts on the critical contribution that adequate food and good nutrition make to academic success. Accordingly, it provides three balanced meals a day to all its students, some of whom might otherwise have little else to eat on school days. For those who can’t get to school in time for early breakfast, a substitute meal is offered after first period, to be eaten during the second period. Every student can pick up dinner at the end of the school day, and those who play sports after school can take the dinner with them to practices and games. To Jennifer Funkhauser, a French teacher at Harding and hands-on participant in the meal program, making sure the students are well fed is paramount to their ability to succeed academically. Ms. Funkhauser and the staff at Harding are well aware of the many studies showing that children who are hungry or malnourished have a hard time learning. After she noticed that some youngsters were uncomfortable eating with hundreds of others in a large, noisy lunchroom, Ms. Funkhauser created a more private, quieter “lunch bunch” option for them. The attitude and atmosphere at Harding are in stark contrast to the humiliating lunchroom experiences suffered by students at some schools, where youngsters are sometimes shamed in front of their classmates and their meals confiscated and dumped in the garbage when parents have an unpaid lunch bill. © 2017 The New York Times Company

Keyword: Development of the Brain
Link ID: 23706 - Posted: 06.05.2017

By Amina Zafar, CBC News When men postpone meal times, it delays one of the body's clocks, British researchers say, a finding that sheds light on a potential way to overcome jet lag and health harms for shift workers. Our bodies run a roughly 24-hour cycle called the circadian or sleep/wake rhythm. It is controlled by a master "clock" in the brain that responds to light signals from the retina, synchronizing other clocks throughout the body. Now investigators have discovered that a five-hour delay in meal time causes a five-hour delay in blood glucose rhythms. "We think this is due to changes in clocks in our metabolic tissues but not the 'master' clock in the brain," said Jonathan Johnston of the University of Surrey, one of the authors of the study published in Thursday's issue of the journal Current Biology. "This work is important because it demonstrates for the first time that a relatively subtle change of standard human feeding pattern re-synchronizes key metabolic rhythms in the body." Currently, people disoriented by the sluggish time warp of jet lag may take melatonin supplements and time their light exposure to help synchronize their clocks. While the study introduces the idea of adding meal timing to the clock reset toolkit, the practical details of how to do so still need to be worked out. In the experiment, 10 healthy young men came to a specialized sleep lab for 13 days. At first, breakfast was set for 30 minutes after waking. Then, after the men got used ©2017 CBC/Radio-Canada.

Keyword: Biological Rhythms; Obesity
Link ID: 23695 - Posted: 06.02.2017

Alexandra Sifferlin Like most people, Kevin Hall used to think the reason people get fat is simple. "Why don't they just eat less and exercise more?" he remembers thinking. Trained as a physicist, the calories-in-vs.-calories-burned equation for weight loss always made sense to him. But then his own research--and the contestants on a smash reality-TV show--proved him wrong. Hall, a scientist at the National Institutes of Health (NIH), started watching The Biggest Loser a few years ago on the recommendation of a friend. "I saw these folks stepping on scales, and they lost 20 lb. in a week," he says. On the one hand, it tracked with widespread beliefs about weight loss: the workouts were punishing and the diets restrictive, so it stood to reason the men and women on the show would slim down. Still, 20 lb. in a week was a lot. To understand how they were doing it, he decided to study 14 of the contestants for a scientific paper. Hall quickly learned that in reality-TV-land, a week doesn't always translate into a precise seven days, but no matter: the weight being lost was real, speedy and huge. Over the course of the season, the contestants lost an average of 127 lb. each and about 64% of their body fat. If his study could uncover what was happening in their bodies on a physiological level, he thought, maybe he'd be able to help the staggering 71% of American adults who are overweight. © 2017 Time Inc.

Keyword: Obesity
Link ID: 23670 - Posted: 05.29.2017

Laura Sanders Nerve cells in a poorly understood part of the brain have the power to prompt voracious eating in already well-fed mice. Two to three seconds after blue light activated cells in the zona incerta, a patch of neurons just underneath the thalamus and above the hypothalamus, mice dropped everything and began shoveling food into their mouths. This dramatic response, described May 26 in Science, suggests a role in eating behavior for a part of the brain that hasn’t received much scrutiny. Scientists have previously proposed a range of jobs for the zona incerta, linking it to attention, movement and even posture. The new study suggests another job — controlling eating behavior, perhaps even in humans. “Being able to include the zona incerta in models of feeding is going to help us understand it better,” says study coauthor Anthony van den Pol, a neuroscientist at Yale University. The new results may also help explain why a small number of Parkinson’s disease patients develop binge-eating behavior when electrodes are implanted in their brains to ease their symptoms. Those electrodes may be stimulating zona incerta nerve cells, van den Pol suspects. He and his collaborator Xiaobing Zhang, also of Yale, studied the mice with a technique called optogenetics. Mice were engineered so that some nerve cells in the zona incerta fired off signals when hit with blue light. When the light activated these cells, the mice immediately found the food and began eating, the researchers reported. “It’s really quick,” van den Pol says. |© Society for Science & the Public 2000 - 2017.

Keyword: Obesity
Link ID: 23664 - Posted: 05.26.2017

Claude Messier, Alexandria Béland-Millar, The short answer is yes: certain brain regions do indeed consume more energy when engaged in particular tasks. Yet the specific regions involved and the amount of energy each consumes depend on the person’s experiences as well as each brain’s individual properties. Before we delve into the answer, it is important to understand how we measure a brain’s energy expenditure. Picture the colorful brain images researchers use to display neural activity. The colors typically represent the amount of oxygen or glucose various brain regions use during a task. Our brain is always active on some level—even when we are not engaged in a task—but it requires more energy to accomplish something that demands concentration such as moving, seeing or thinking. A simple example is that our primary visual cortex lights up more in brain scans—consuming more energy—when our eyes are open than when they are closed. Similarly, our primary motor cortex uses more energy if we move our hands than if we keep them still. Say you are learning a new skill—how to juggle or speak Spanish. Neuroscientists have made the fascinating observation that when we do something completely novel, a broad range of brain areas becomes active. As we become more skilled at the task, however, our brain becomes more focused: we require only the essential brain regions and need increasingly less energy to perform that task. Once we have mastered a skill—we become fluent in Spanish—only the brain areas directly involved remain active. Thus, learning a new skill requires more brainpower than a well-practiced activity. © 2017 Scientific American

Keyword: Brain imaging
Link ID: 23647 - Posted: 05.23.2017

By Catherine Caruso If you give a mouse a beer, he is going to want a cookie—and another, and another. If you give a person enough beer, she might find herself wolfing down a plate of greasy nachos or some other caloric snack. A study published in January in Nature Communications helps to explain why binge drinking, in both mice and humans, so often leads to binge eating even though alcohol is, itself, high in calories. In the first part of the study, neuroscientists Craig Blomeley and Sarah Cains, both at the Francis Crick Institute Mill Hill Laboratory in London, injected mice with the equivalent of roughly two bottles of wine once a day for three consecutive days, mimicking a weekend of heavy drinking. Sure enough, the inebriated mice ate far more than sober mice in a control group. To figure out why, the researchers then exposed thin-sliced postmortem mouse brains to alcohol and measured the resulting neural activity using fluorescent tags and electrodes. They found that ethanol exposure alters calcium exchange in the cells, causing specialized nerve cells called agouti-related protein (AgRP) neurons to fire more frequently and easily. These neurons normally fire when our body needs calories, and research has shown that activating them artificially will cause mice to chow down even when they are full. The study results suggest that alcohol activates AgRP neurons in the brain, giving drunk mice the munchies. The same is likely true for humans because this brain circuitry has been highly conserved across mammal species, Cains says: “I don't doubt that AgRP neurons are activated in humans, and that's why you see this effect.” © 2017 Scientific American

Keyword: Drug Abuse; Obesity
Link ID: 23645 - Posted: 05.22.2017

Sarah Boseley in Porto A crinkly plate, designed with ridges that cunningly reduce the amount of food it holds, may be heading for the market to help people concerned about their weight to eat less. The plate is the brainchild of a Latvian graphic designer, Nauris Cinovics, from the Art Academy of Latvia, who is working with a Latvian government agency to develop the idea and hopes to trial it soon. It may look like just another arty designer plate, but it is intended to play tricks with the mind. “My idea is to make food appear bigger than it is. If you make the plate three-dimensional [with the ridges and troughs] it actually looks like there is the same amount of food as on a normal plate – but there is less of it,” said Cinovics. “You are tricking the brain into thinking you are eating more.” The plate will be made of clear glass and could turn eating dinner into a more complex and longer process than it is usually for most of us. Negotiating the folds in the glass where pieces of fish or stray carrots may lurk will slow down the speed with which people get through their meal. Cinovics has also designed heavy cutlery, with the idea of making eating more of a labour – that therefore lasts longer. His knife, fork and spoon weigh 1.3kg each. “We tested this and it took 11 minutes to finish a meal with this cutlery rather than seven minutes,” he said.

Keyword: Obesity; Attention
Link ID: 23639 - Posted: 05.20.2017

By: Ted Dinan, M.D., Ph.D, and John F. Cryan, Ph.D. O ver the past few years, the gut microbiota has been implicated in developmental disorders such as schizophrenia and autism, neurodegenerative disorders such as Alzheimer’s disease and Parkinson’s disease, mood disorders such as depression, and even addiction disorders. It now seems strange that for so many decades we viewed the gut microbiota as bacteria that did us no harm but were of little benefit. This erroneous view has been radically transformed into the belief that the gut microbiota is, in effect, a virtual organ of immense importance. What we’ve learned is that what is commonly referred to as “the brain-gut-microbiota axis” is a bidirectional system that enables gut microbes to communicate with the brain and the brain to communicate back to the gut. It may be hard to believe that the microbes in the gut collectively weigh around three pounds—the approximate weight of the adult human brain—and contain ten times the number of cells in our bodies and over 100 times as many genes as our genome. 1 If the essential microbial genes were to be incorporated into our genomes, it is likely that our cells would not be large enough for the extra DNA. Many of those genes in our microbiota are important for brain development and function; they enable gut bacteria to synthesize numerous neurotransmitters and neuromodulators such as γ-aminobutyric acid (GABA), serotonin, dopamine, and short-chain fatty acids. While some of these compounds act locally in the gut, many products of the microbiota are transported widely and are necessary for the proper functioning of diverse organs. This is a two-way interaction: gut microbes are dependent on us for their nourishment. Any pathological process that reduces or increases food intake has implications for our microbes. © 2017 The Dana Foundation. All Rights Reserved.

Keyword: Parkinsons
Link ID: 23636 - Posted: 05.19.2017

By RONI CARYN RABIN Q. How can a blood test determine if I have prediabetes? How much weight do I need to lose to bring my numbers down? A. Doctors typically perform one of three blood tests to diagnose prediabetes, a condition marked by blood sugar (glucose) levels that are higher than normal but not high enough to qualify as diabetes. While prediabetes often leads to full-fledged Type 2 diabetes, many people can hold the condition in check if they lose a relatively small amount of weight and increase their physical activity, said Dr. Rhonda Bentley-Lewis, an assistant professor of medicine at Harvard Medical School. “I stress to my patients that we’re not talking about a huge amount of weight,” she said, “just 5 to 7 percent of one’s body weight” — or 10 to 14 pounds for someone who weighs 200 pounds. Two of the tests require fasting, which helps prevent results being distorted by a prior meal and provides “an even baseline,” Dr. Bentley-Lewis said. One, the fasting plasma glucose test, checks blood glucose levels after an 8 to 10 hour fast; results of 100 to 125 milligrams per deciliter indicate prediabetes. The other, the oral glucose tolerance test, is the most sensitive. It checks blood glucose levels after fasting and then two hours after you consume a sweetened drink; levels of 140 to 199 after the drink indicate prediabetes. A third test, the A1C test, may be the most convenient because it doesn’t require fasting. It measures your average blood glucose levels over the past two to three months; results of 5.7 percent to 6.4 percent, which indicate the percentage of red blood cells that have glucose attached to them, indicate prediabetes. Though doctors often repeat a test to confirm a diabetes diagnosis, they do not always do so for a prediabetes diagnosis, Dr. Bentley-Lewis said. Doctors can treat prediabetes with medication, but many patients prefer to try weight loss and exercise first, Dr. Bentley-Lewis said. Among thousands of people with prediabetes who participated in a national study called the Diabetes Prevention Program, 58 percent of those who adopted lifestyle changes, like losing a modest amount of weight, stepping up physical activity and reducing the amount of fat and calories in their diets, were able to prevent progression to full-blown diabetes. © 2017 The New York Times Company

Keyword: Obesity
Link ID: 23634 - Posted: 05.19.2017

Sarah Boseley in Porto A balloon that can be swallowed and then filled with water while in the stomach can help obese people to lose large amounts of weight without invasive surgery, a new study has shown. Bariatric surgery to reduce the size of the stomach is highly effective, but anaesthesia for somebody who is very overweight can be risky. Those who want to undergo the surgery must also undergo a long period of preparation to ready them physically and psychologically. It is expensive, and there is a long waiting list in the UK, even though NHS guidance recommends it be considered. The balloon is swallowed like a pill, but with a long thin tube attached. Ultrasound is used to determine when the balloon is in place in the stomach, and it is then filled with water through the tube. The tube then detaches and is pulled back up the throat and out. Unlike gastric surgery, the balloon is a temporary measure. After 16 weeks, it bursts in the stomach, the water is released and the balloon itself is excreted. A small study presented at the European Congress on Obesity in Porto, Portugal, showed that the 38 patients enrolled in the trial had lost a mean 15.2kg (33.5 lbs) by the end of the 16 weeks, which amounted to about a third (mean 31%) of their excess weight.

Keyword: Obesity
Link ID: 23629 - Posted: 05.18.2017

Sarah Boseley People who are obese run an increased risk of heart failure and stroke even if they appear healthy, without the obvious warning signs such as high blood pressure or diabetes, according to a major new study. The findings, presented at the European Congress on Obesity in Porto, Portugal, may be the final death knell for the claim that it is possible to be obese but still metabolically healthy – or “fat but fit” – say scientists. Several studies in the past have suggested that the idea of “metabolically healthy” obese individuals is an illusion, but they have been smaller than this one. The new study, from the University of Birmingham, involved 3.5 million people, approximately 61,000 of whom developed coronary heart disease. Is it possible to be healthy and obese? The issue has been controversial. Obesity is usually measured by body mass index (BMI) – a ratio of weight against height. It is generally agreed to be imperfect because athletes and very fit people with dense muscle can have the same BMI as somebody who is obese. The scientists examined electronic health records from 1995 to 2015 in the Health Improvement Network – a large UK general practice database. They found records for 3.5 million people who were free of coronary heart disease at the starting point of the study and divided them into groups according to their BMI and whether they had diabetes, high blood pressure [hypertension], and abnormal blood fats [hyperlipidemia], which are all classed as metabolic abnormalities. Anyone who had none of those was classed as “metabolically healthy obese”.

Keyword: Obesity
Link ID: 23623 - Posted: 05.17.2017

By ROXANNE KHAMSI What lengths will a dog go to for a bite of sausage? Last November, scientists at the University of Cambridge in Britain persuaded several dozen pet owners to bring their Labrador retrievers to its veterinary school for a true test of will. Inside a mostly empty white room, a research associate let each dog sniff a hot dog before demonstratively placing it inside a small plastic hamster cage on the floor and sealing it shut with black duct tape. Some of the Labs showed only passing interest in the trapped sausage and spent more time exploring the rest of the room. But others stayed laser-focused on the treat. One in particular, a black Labrador named Ash, went into a tizzy, banging the cage around and not giving up until he pried the tape loose with his teeth and ate the hot dog. As it turns out, Ash has more than just determination and a precise tooth grip. He also has a gene mutation linked to obesity. Ash is not overweight, perhaps because his owner keeps him on a rigid diet. But Eleanor Raffan, the researcher who designed the study, suspects his underlying gene mutation and his food-induced frenzy in the experiment are linked. She hasn’t yet analyzed all the data from this latest study, but it has become a mission of hers to understand what makes some canines so voracious. Raffan’s curiosity about this traces back 15 years, to when she became a veterinary surgeon and saw firsthand that certain breeds are more likely than others to put on extra weight. Shortly afterward, when scientists published the first complete dog genome, Raffan decided she wanted to search for DNA mutations that might contribute to heaviness. She got a doctorate in genetics and in 2013 began the GOdogs Project — short for the genetics of obesity in dogs — at Cambridge. She notes that because of the way people have bred dogs, there’s a small gene pool within each breed, making the animals simpler to study: “The way the jiggery-pokery of genetics works means that it’s remarkably easy to get to map the sites where disease-​causing genes are in dogs,” Raffan says. © 2017 The New York Times Company

Keyword: Obesity; Genes & Behavior
Link ID: 23619 - Posted: 05.16.2017

By GINA KOLATA Researchers have traced the cause of a baffling brain disorder to a surprising source: a particular type of bacteria living in the gut. Scientists increasingly suspect that the body’s vast community of bacteria — the microbiome — may play a role in the development of a wide variety of diseases, from obesity to perhaps even autism. The new study, published on Wednesday in Nature, is among the first to suggest convincingly that these bacteria may initiate disease in seemingly unrelated organs, and in completely unexpected ways. Researchers “need to be thinking more broadly about the indirect role of the microbiome” in influencing even diseases that have no obvious link to the gut, said Dr. David Relman, professor of microbiology and immunology at Stanford. The researchers studied hereditary cerebral cavernous malformations — blood-filled bubbles that protrude from veins in the brain and can leak blood or burst at any time. The findings do not point to a cure, but they do suggest a way to prevent these brain defects in children who inherit a mutated gene that can cause them. Researchers warned, though, that it is too soon to say whether the potential treatment — antibiotics, followed by a fecal transplant — will work. “Caution, caution, caution,” urged Dr. Mark Ginsberg, a professor of medicine at the University of California, San Diego, who was not involved in the new study. Still, he added, “The findings are very convincing.” When Dr. Mark Kahn, professor of cardiovascular medicine at the University of Pennsylvania’s Perelman School of Medicine, began this work, the microbiome was the last thing on his mind. © 2017 The New York Times Company

Keyword: Stroke; Epilepsy
Link ID: 23603 - Posted: 05.11.2017

Have you ever found yourself craving a steak or a burger? The brain controls our feelings of hunger and also determines the types of nutrients we should be seeking out. Not much is understood about the brain’s regulation of nutrient-specific hunger, but in a new study published in Science, researchers identified the brain cells in fruit flies that regulate protein hunger and were able to control those cells, affecting what the animals ate. The study, was funded by the National Institute of Neurological Disorders and Stroke (NINDS), part of the National Institutes of Health. To study protein hunger, a team of researchers led by Mark Wu, M.D., Ph.D., associate professor of neurology at Johns Hopkins University in Baltimore, starved flies of yeast (the animal’s protein source) for one week. Afterwards, they discovered that the flies ate more yeast and less sugar than flies that ate a control diet. “Flies have been a great model system for brain research so we can learn a lot about how our own brain circuits work by peeking inside the heads of flies,” said Janet He, Ph.D., program director at the NINDS. “A better understanding of the basic mechanisms that regulate the consumption of different nutrients may help to provide clues to addressing the obesity epidemic.” Using novel genetic tools, Dr. Wu’s team identified a specific circuit, a set of brain cells that communicate with one another, which controls protein-seeking behavior. When the circuit was stimulated, flies ate more yeast than normal. In contrast, when the researchers turned off the circuit, the flies ate less yeast. The cells in the circuit were more active, which was demonstrated by increased firing activity, when the flies were starved of yeast. Turning the circuit on or off did not affect the animals’ general hunger or thirst.

Keyword: Obesity
Link ID: 23601 - Posted: 05.11.2017