Chapter 9. Homeostasis: Active Regulation of the Internal Environment
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A substance made by the body when it uses fat as fuel could provide a new way of treating epilepsy, experts hope. Researchers in London who have been carrying out preliminary tests of the fatty acid treatment, report their findings in Neuropharmacology journal. They came up with the idea because of a special diet used by some children with severe, drug resistant epilepsy to help manage their condition. The ketogenic diet is high in fat and low in carbohydrate. The high fat, low carbohydrate diet is thought to mimic aspects of starvation by forcing the body to burn fats rather than carbohydrates. Although often effective, the diet has attracted criticism, as side-effects can be significant and potentially lead to constipation, hypoglycaemia, retarded growth and bone fractures. By pinpointing fatty acids in the ketogenic diet that are effective in controlling epilepsy, researchers hope they can develop a pill for children and adults that could provide similar epilepsy control without the side-effects. In early trials, the scientists, from Royal Holloway and University College London, say they have identified fatty acids that look like good candidates for the job. They found that not only did some of the fatty acids outperform a regular epilepsy medication called valproate in controlling seizures in animals, they also had fewer side-effects. BBC © 2012
The search for genes predisposing people to depression has taken an unexpected twist, according to Canadian researchers who found a clue in an obesity gene. Studies on families and twins suggest depression has a genetic component, but for 15 years, scientists haven't been able to find genes associated with the illness. Researchers at McMaster University in Hamilton, Ont., took a different approach by testing how obesity genes may be linked with depression. "We found the first gene predisposing to depression with consistent results," said David Meyre, an associate professor in clinical epidemiology and biostatistics at McMaster and a Canada Research Chair in genetic epidemiology. In Monday's issue of the journal Molecular Psychiatry, Meyre and his co-authors reported that a variant of the FTO gene may be associated with a lower risk of depression independent of the gene's effect on obesity. The common perception is that obese people become depressed because of their appearance and poor self-esteem or discrimination. Another common thought is that those who are depressed are less likely to be physically active or follow healthy eating habits. Taking antidepressants can also lead to weight gain. But the genetic findings challenge that thinking, Meyre said, since those with the genetic mutation predisposing to obesity were protected from depression. "This suggests that the FTO gene may have a broader role than initially thought with an effect on depression and other common psychiatric disorders," the researchers wrote. © CBC 2012
By Lindsey Emery, Men’s Health When most people finish a hard workout, they want a reward — possibly a sandwich, or some pancakes, or maybe even a burger and fries. What they don’t want? To not eat anything. And yet, a few recent studies found that moderate intensity aerobic training could actually decrease your appetite or increase your feelings of fullness or satiety. Strange, right? Previous research has shown that people who exercise often reward themselves with food, increasing overall calorie consumption, and often sabotaging their weight loss goals. So, what gives? “Exercise can definitely suppress hunger,” says Barry Braun, director of the Energy Metabolism Laboratory at the University of Massachusetts, Amherst, who has co-authored multiple studies on the subject. How, why, and for how long afterward is something researchers are still working out. They do know that workouts trigger changes in the hunger hormone ghrelin and the satiety hormones, PYY and GLP-1 — though research has yet to establish the exact relationship. A recent study published in the journal Metabolism found that perceived fullness — both while fasting and after eating — was higher among participants after 12 weeks of aerobic training, but not after resistance training for the same amount of time. And another study out of Brigham Young University revealed that women appeared to be less interested in food on mornings when they walked on a treadmill for 45 minutes than on days they didn’t. © 2012 NBCNews.com
Link ID: 17473 - Posted: 11.10.2012
By GRETCHEN REYNOLDS In recent years, some research has suggested that a high-fat diet may be bad for the brain, at least in lab animals. Can exercise protect against such damage? That question may have particular relevance now, with the butter-and cream-laden holidays fast approaching. And it has prompted several new and important studies. The most captivating of these, presented last month at the annual meeting of the Society for Neuroscience in New Orleans, began with scientists at the University of Minnesota teaching a group of rats to scamper from one chamber to another when they heard a musical tone, an accepted measure of the animals’ ability to learn and remember. For the next four months, half of the rats ate normal chow. The others happily consumed a much greasier diet, consisting of at least 40 percent fat. Total calories were the same in both diets. After four months, the animals repeated the memory test. Those on a normal diet performed about the same as they had before; their cognitive ability was the same. The high-fat eaters, though, did much worse. Then, half of the animals in each group were given access to running wheels. Their diets didn’t change. So, some of the rats on the high-fat diet were now exercising. Some were not. Ditto for the animals eating the normal diet. For the next seven weeks, the memory test was repeated weekly in all of the groups. During that time, the performance of the rats eating a high-fat diet continued to decline so long as they didn’t exercise. Copyright 2012 The New York Times Company
By ANDREW POLLACK Allergan said Tuesday that it was looking to divest itself of its Lap-Band, the once-popular weight-loss device that has experienced several years of falling sales, loss of market share and controversies about its safety and effectiveness. The falling sales “do not fit the profile of a high-growth company like Allergan,” David E. I. Pyott, the company’s chief executive, told analysts Tuesday morning on a call announcing the company’s third-quarter financial results. In an interview, Mr. Pyott said Allergan had already hired an investment banking firm, which he would not name, and was sending letters to other medical device companies and private equity firms seeking a buyer for its obesity business, which also includes a balloonlike device that is not approved in the United States but is used in some other countries. The Lap-Band, a silicone ring that is wrapped around the stomach and can be inserted in an outpatient procedure, once appeared to have a bright future as a less drastic, if less effective, alternative to gastric bypass, which involves rerouting the digestive tract. But Allergan’s obesity business sales have fallen from a peak of $296 million in 2008 to an expected $160 million this year. In the third quarter, the sales fell by 25 percent to $37.4 million from a year earlier. The obesity business, while still profitable, represents less than 3 percent of total product sales for Allergan, which is known most for its Botox treatment for wrinkles, migraine headaches and other conditions. © 2012 The New York Times Company
Link ID: 17440 - Posted: 10.31.2012
People often don't know how many calories they're eating, how many they burn off, or what they need, say doctors who are calling for prominent calorie labels at the point of sale. The Canadian Obesity Network, a group of obesity experts, showed people examples of foods and asked them to guess how many calories the items contained. Many people don't know their recommended daily intake of calories.Many people don't know their recommended daily intake of calories. (Lee Jae Won/Reuters) "A lot of Canadians were quite off the mark," said Dr. Arya Sharma, chair in obesity research and management at the University of Alberta in Edmonton. "When we showed people food labels and asked them to calculate how many calories they'd be getting if they consumed say a can of soup, very few Canadians were able to figure out that number." Sharma is concerned about the consequences of caloric illiteracy considering two-thirds of Canadians are carrying extra pounds and a quarter of adults are considered to be medically obese, according to Statistics Canada. "Ultimately calories are the currency of weight management," Sharma said. "If you don't know how many calories you're eating, you don't know what your body's doing with the calories, you don't know where the calories are going. That's like trying to manage your bank account without knowing how much money you make or how much money things cost." © CBC 2012
Link ID: 17431 - Posted: 10.29.2012
By Katherine Harmon Getting seven to eight solid hours of sleep each night might seem an almost impossible luxury to many people. But not getting enough sleep is known to impair mental function and increase the risk for heart disease, among other ill effects. Accumulating evidence also suggests that even short-term, partial sleep deprivation could pave the way for weight gain and other negative metabolic consequences. More than 28 percent of adults in the U.S. report that they get less than six hours of sleep a night, with this cumulative deprivation becoming more common in the past three decades. And now that more than 35 percent of U.S. adults are currently obese, researchers have been searching for potential links between the two conditions, in hopes of reducing the increasing health and economic burden of obesity. Establishing lack of sleep as a risk factor for weight gain could have important clinical and public health effects, possibly allowing people to make simple lifestyle changes to improve their metabolic health. A new report, published online October 24 in the Journal of the Academy of Nutrition and Dietetics, reviews 18 carefully controlled laboratory studies that tested human subjects' physiological and behavioral responses to sleep deprivation as they relate to metabolic health. Reena Mehra, an associate professor of medicine who studies sleep and health at Case Western Reserve University School of Medicine and who was not involved in the new analysis, notes that the new paper is "a well done review of the experimental data." © 2012 Scientific American
by Shaoni Bhattacharya Talk about having your cake and eating it. Fasting might not be the only route to a longer life – a hormone seems to work just as well, for mice at least. We know that some animals can extend their lifespan by consuming fewer calories. Engineered mice can get the same effect by simply pumping out high levels of a hormone normally produced during a fast, according to Steven Kliewer and David Mangelsdorf at the University of Texas Southwestern Medical Center in Dallas. Their team found that mice engineered to make higher levels of the hormone, FGF21, increased their lifespan on average by over a third. "What we are seeing is the benefit of caloric restriction without having to diet," he says. Humans have the hormone too, and Kliewer believes FGF21 has the potential to extend the human "health-span" – the time we live healthy lives. The researchers believe FGF21 may act to prolong life by affecting pathways such as the insulin-like growth factor-1 (IGF-1) pathway implicated in ageing. "It blocks growth hormones promoting pathways which are associated with diseases, including cancers and metabolic diseases, and as a consequence these animals live longer," says Kliewer. © Copyright Reed Business Information Ltd.
By JANE E. BRODY I recently met a slender, health-conscious young woman who insisted that the size of sugar-sweetened drinks should not be legislated. “Getting people to drink less of them should be done through education,” she said. It is an opinion shared by many others. Some may be unaware of the role that these beverages are playing in the nation’s burgeoning epidemics of obesity and Type 2 diabetes. Few know the disappointing history of efforts to change human behavior solely through education. The young woman was reacting to a New York City regulation, to take effect on March 12, limiting to 16 ounces the size of sugar-sweetened soft drinks available for purchase at restaurants, street carts, movie theaters and sporting events. The Barclays Center in Brooklyn, the new home of the Nets, has already imposed this limit. Convenience stores, vending machines and some newsstands are exempted from the regulation. Several new studies underscore the public health potential of the restriction. If it succeeds in curbing the consumption of sweet liquid calories, it is likely to be copied elsewhere, because the nation’s love affair with super-size sugary soft drinks is costing cities and states billions of dollars annually in medical care. We are all born with a natural preference for sweetness, which through evolution enabled us to know when fruits and berries were ripe and ready to eat. But as Gary K. Beauchamp, a biopsychologist and director of the Monell Chemical Senses Center in Philadelphia, has put it, “We’ve separated the good taste from the good food.” Our sweet tooth is no longer working to our advantage. Copyright 2012 The New York Times Company
Link ID: 17400 - Posted: 10.22.2012
By Tina Hesman Saey New work suggests that a hormone that makes the body think it’s starving could prolong life about as long as severely cutting calories does but without the denial. A hormone called fibroblast growth factor-21, or FGF21, lengthened the lives of mice that had been genetically engineered to constantly produce large amounts of the protein, researchers at the University of Texas Southwestern Medical Center at Dallas report online October 15 in eLife. The hormone is normally made by the liver during fasting and may tap into some of the same life-extending biochemical processes as does caloric restriction, a proven longevity booster. Caloric restriction — usually defined as cutting calorie intake to 75 to 80 percent of the amount needed to maintain normal body weight, while still maintaining good nutrition — has been shown lengthen life in a wide variety of species, such as fruit flies and dogs. Minimal calorie consumption turns on many different biological processes that slow aging, says Cynthia Kenyon, a developmental biologist at the University of California, San Francisco. The hormone in the study somehow interferes with a chain reaction anchored by insulin-like growth factor-1 (IGF-1), a process that is also shut down by caloric restriction and thought to be responsible for many of its life-extending effects. In the study, researchers led by UT Southwestern’s David Mangelsdorf and Steven Kliewer genetically engineered mice to constantly make five to 10 times as much FGF21 as normal. These engineered mice lived 30 to 40 percent longer than normal mice on a standard diet. Female mice benefitted from the hormone even more than males; about a third of the FGF21-producing female mice still were alive at 44 months old. Average survival for normal mice in the study was about 28 months. © Society for Science & the Public 2000 - 2012
By Nick Triggle Health correspondent, BBC News Obesity surgery is often seen as a quick fix, without proper consideration of the risks, a review says. The National Confidential Enquiry into Patient Outcome and Death looked at the care given to more than 300 patients at NHS and private hospitals in England, Wales and Northern Ireland. It found that many were given insufficient time or information to properly consent to the operations. Post-surgery care was also found to be lacking, the watchdog said. In particular, it highlighted the fact patients were not always given access to dieticians and psychologists. The report also suggested the failings could be contributing to the high number of readmissions - nearly a fifth of the patients had to return within six months. Weight loss operations, such as the fitting of gastric bands, have been growing in popularity. There were more than 8,000 of these operations, sometimes called bariatric surgery, carried out by the NHS last year - and the number is rising by about 10% a year. BBC © 2012
Link ID: 17387 - Posted: 10.18.2012
By Janet Raloff Carbon dioxide has been vilified for decades as a driver of global warming. A new study finds signs that CO2, exhaled in every breath, can exert an equally worrisome threat — impaired cognition — in nearly every energy-efficient classroom, meeting hall or office space. The work assessed decision-making in 22 healthy young adults. Their performance on six of nine tests dropped notably when researchers raised indoor carbon dioxide levels to 1,000 parts per million from a baseline of 600 ppm. On seven tests, performance fell substantially more when the room’s CO2 was boosted to 2,500 ppm, scientists report in a paper to be published in Environmental Health Perspectives. These data are surprising, says Roger Hedrick of Architectural Energy Corp. in Boulder, Colo., because “1,000 ppm of CO2 used to be considered a benchmark of good ventilation.” Hedrick, an environmental engineer, chairs the committee that drafts commercial ventilation standards through the American Society of Heating, Refrigerating, & Air-Conditioning Engineers. Carbon dioxide levels are often substantially higher in buildings than the 350 to 400 ppm typically found outdoors. Indoor values of 600 ppm are considered very good. But depending on how many people inhabit a room and how many times per hour its air is exchanged with outdoor air through ventilation, “there are plenty of buildings where you could easily see 2,500 ppm of CO2 — or close to it — even with ventilation designs that are fully compliant with current standards,” Hedrick says. © Society for Science & the Public 2000 - 2012
Keyword: Learning & Memory
Link ID: 17380 - Posted: 10.17.2012
by Jessica Hamzelou Never underestimate the value of a good night's sleep. Not only does a lack of shut-eye leave you irritable, it has been linked to diabetes and weight gain, though no one understood why. To investigate, Matthew Brady at the University of Chicago and his colleagues tested fat cells taken from the bellies of seven adults after four nights of sleeping up to 8 and a half hours, and then again after four nights on a measly 4 and a half hours. The team found that after sleep deprivation fat cells from the same person were on average 30 per cent less responsive to insulin – a hormone that makes muscle, liver and fat cells take up glucose after a meal. High blood glucose levels are linked to diabetes. Fat cells also normally release the appetite-regulating hormone leptin. Brady suggests that if sleep-deprived cells are generally malfunctioning, this mechanism may also be disrupted, affecting weight gain. "We were surprised at how robust the response was," says Brady. "Four nights of sleep curtailment represents a real-world situation, such as sitting for final exams or having a newborn in the house." Journal reference: Annals of Internal Medicine, DOI: 10.7326/0003-4819-157-8-201210160-00005 © Copyright Reed Business Information Ltd.
By LAURA GEGGEL For years, young people — often girls and young women — have frequented Web sites promoting anorexia and bulimia as a source of inspiration and tips on staying thin, even as online companies have worked to ban such content. Now, groups and Web sites focused on recovery from eating disorders are fighting back. “We need to be looking at these communities and see what we can learn from them, and what we can provide as a positive alternative,” said Claire Mysko, manager of Proud2Bme.org, a Web site and online community focused on healthy recovery that is financed by the nonprofit National Eating Disorders Association. “That’s what we’re trying to do here.” This Saturday, the group is taking its message to the University of South Florida in Tampa for its free annual Proud2Bme Summit. Attendees will be encouraged to engage in activities like taking a stand on Twitter against “body snarking,” a bullying tactic that draws attention to a person’s body or weight gain, and hear from speakers including Julia Bluhm, a 14-year-old who collected more than 86,000 signatures to petition Seventeen magazine to print one unaltered photo spread a month. “Our goal here is to make it a space where people can connect,” Ms. Mysko said. The site began in 2011 after the success of its Dutch counterpart, Proud2Bme.nl, whose co-founder Scarlet Hemkes struggled with anorexia and bulimia as a teenager and young adult and was horrified to find countless sites where girls competed to lose weight or shared tips on how to lie to parents about weight loss. Inspired by France’s move in 2008 to ban such sites — commonly called pro-ana (for pro-anorexia) sites — Ms. Hemkes collected 10,000 signatures with the hopes of inspiring similar Dutch legislation. When that didn’t work, she created a community on Hyves, a Facebook-like social network for girls with eating disorders, before founding Proud2Bme with a psychologist, Eric van Furth, in 2009. Copyright 2012 The New York Times Company
Keyword: Anorexia & Bulimia
Link ID: 17368 - Posted: 10.13.2012
By LISA SANDERS, M.D. On Thursday, we challenged Well readers to try their hand at solving the case of a comatose young woman dropped off at the emergency room by her friends after attending a concert the previous night. More than 350 people wrote in, and more than 90 of you were able to figure it out. The Correct Diagnosis Is … … Ecstasy-induced hyponatremia. Over the past 20 years there have been many reports of young people, mostly young women, who have had seizures or become unconscious after taking the illegal drug Ecstasy, also known as MDMA. The cause is a dangerously low level of sodium in the bloodstream. The brain is exquisitely sensitive to the exact right balance of sodium and water, and when they are out of whack, nausea, confusion and seizures can follow. It’s a rare but dangerous side effect of the drug. Nearly one in five patients reported to have this complication died. Others had permanent brain damage. When this complication was first observed, it was thought to be because of an overconsumption of water. The drug was used widely at concerts or “raves,” and attendees were told to drink lots of water to replace what was sweated out in the crowded, hot concert and dance floors. Further research revealed that the drug actually alters the way the brain and the kidney work so that the body holds on to water and dumps sodium. This change is exaggerated by the presence of estrogen, so women are far more likely to be affected than men. Why the drug can have this effect on any given individual is not well understood, but it is clear that it is not because of an overdose or a contaminant. It appears to be a response to the drug itself. Copyright 2012 The New York Times Company
Keyword: Drug Abuse
Link ID: 17338 - Posted: 10.06.2012
by Marissa Miley A virus that may encourage the body to grow more fat cells could, paradoxically, lower diabetes risk. Nikhil Dhurandhar at the Pennington Biomedical Research Center in Baton Rouge, Louisiana, and colleagues examined the long-term effects of a common virus – adenovirus-36 (Ad-36) – on humans. The team analysed blood samples made available from 1400 volunteers in a decades-long epidemiological study. The researchers detected antibodies to Ad-36 in 14.5 per cent of the subjects when they first joined the study – a prevalence in line with studies on the US adult population. Ten years later, those individuals naturally infected with Ad-36 had a higher body mass index and body fat percentage than those who were not infected – but their blood sugar and insulin levels were healthier. Animal and cell studies offer an explanation, says Dhurandhar. They suggest that Ad-36 increases the number and size of fat cells, or adipocytes, providing additional "depots" for any fat coming from excessive calorie consumption. Under normal circumstances, the number of these fat storage cells stays constant in adulthood, no matter what dietary choices people make. The extra cells from Ad-36 may make the body more likely to store excess fat, but that means less fat is left to travel to other areas, like the liver, where it can have toxic effects. The adipocytes may also store more sugar, helping to keep blood sugar levels under control and maintaining insulin sensitivity to glucose. © Copyright Reed Business Information Ltd.
Link ID: 17329 - Posted: 10.04.2012
By Deborah Kotz, Globe Staff Is Alzheimer’s disease really a form of diabetes? Let’s call it type 3, because that’s what a Brown Medical School researcher dubbed it back in 2005 when she autopsied the brains of Alzheimer’s patients and found that they had signs of insulin resistance -- an early indicator of diabetes. Since then, however, we haven’t seen a sea-change in preventive treatments based on this idea. Those who carry the gene for hereditary Alzheimer’s aren’t given diabetes drugs to help stave off dementia. Nor are Alzheimer’s patients given insulin injections. What has been getting attention, however, is whether we should make extra efforts to eat a low glycemic diet -- which is low in processed foods, sugar, and starchy carbohydrates that cause quick spikes in blood sugar -- to help protect our brains from developing those gunky amyloid plaques associated with Alzheimer’s. The September issue of the New Scientist advocates for changing our eating patterns with a frightening image of a cracked chocolate brain on its cover. (Chocolate consumption, though, hasn’t been linked to cognitive decline, much to my relief.) New York Times food columnist Mark Bittman pointed out in a recent post that the latest studies provide some persuasive evidence linking diet to the development of Alzheimer’s. I’ve covered those studies too, including this one that measured a smaller Alzheimer’s risk in people who eat a diet rich in fish, veggies, and fruit compared with those who eat a diet centered on processed foods containing trans fats. © 2012 NY Times Co.
Link ID: 17328 - Posted: 10.03.2012
By Janet Raloff Most people would never equate downing a well-dressed salad or a fried chicken thigh with toking a joint of marijuana. But to Joseph Hibbeln of the National Institutes of Health, the comparison isn’t a big stretch. New animal experiments by Hibbeln and his colleagues have recently shown that the body uses a major constituent in most vegetable oils to make its own versions of the psychoactive ingredient in marijuana. Called endocannabinoids, these natural compounds play a role in heightening appetite. So overproducing them unnecessarily boosts hunger, similarly to how pot triggers the munchies (SN: 6/19/10, p. 16). If what happens in people mirrors what happens in animals, then the prevalence of soybean oil, corn oil and other polyunsaturated vegetable oils in today’s Western diet means your body is “dumping out a lot of these marijuana-like molecules into your brain,” explains Hibbeln, a nutritional neuroscientist. “You’re chronically a little bit stoned.” Vegetable oil’s link to endocannabinoids is just one example of newfound and surprising ways that foods can confuse calorie-sensing networks and foster obesity — in some cases by damaging the brain. Especially troubling: Excess body weight itself can exaggerate the risk of the brain telling a well-fueled body that it is running on empty. By understanding what messes with the body’s satiety meters and why, scientists hope to identify tactics for reducing a diner’s likelihood of becoming another statistic in the obesity epidemic. © Society for Science & the Public 2000 - 2012
By RONI CARYN RABIN Amid fervid criticism that New York City risks becoming a nanny state, city health officials this month banned the sale of supersize sugar-laden drinks in restaurants and movie theaters. Now scientists have handed the ban’s advocates a potent weapon: strong evidence that replacing sugared drinks with sugar-free substitutes or water really can slow weight gain in children. Two-thirds of all American adults and one-third of children in the United States are overweight or obese. The contribution of sugary sodas and fruit drinks to this epidemic has been hotly disputed. But two new randomized clinical trials published on Friday in The New England Journal of Medicine lend credence to the idea that limiting access to these beverages may help reduce obesity. Beverage industry officials denounced the research, which may fuel wider efforts to curb consumption through taxes or other restrictions. In one of the new trials, researchers at Boston Children’s Hospital randomly assigned 224 overweight or obese teenagers to receive home deliveries of bottled water and diet drinks for one year. The children also were regularly encouraged to avoid sugary drinks. Those who received the shipments gained only 3.5 pounds on average during that year, while a comparison group of similar teenagers gained 7.7 pounds. The differences between the groups evaporated after the deliveries stopped. In the second trial, researchers at VU University Amsterdam randomly assigned 641 normal-weight schoolchildren ages 4 to 11 to drink eight ounces of a 104-calorie sugar-sweetened or noncaloric sugar-free fruit-flavored drink every day from identical cans. Over 18 months, children in the sugar-free group gained 13.9 pounds on average, while those drinking the sugar-added version gained 16.2 pounds. © 2012 The New York Times Company
Children and teens with higher levels of BPA, a chemical used in canned foods, are more likely to be overweight and obese but whether the chemical caused the weight gain can’t be answered. The issue of obesity is addressed in Tuesday's online edition of the Journal of the American Medical Association. In one U.S. study, researchers wanted to test the idea that hormone-like chemicals like bisphenol A, also called BPA, could be contributing to childhood obesity by disrupting kids' metabolism. BPA is used to make hard plastics for food and beverage containers. It also found in the lining of many metal cans. Dr. Leonardo Trasande of the New York University School of Medicine and his co-authors looked at BPA concentrations in the urine of 2,838 Americans aged six to 19 as well as body mass index scores. "Urinary BPA concentrations was significantly associated with obesity in this cross-sectional study of children and adolescents," the study's authors concluded. The researchers weren't able to tell which came first, the obesity or BPA concentrations. © CBC 2012