Chapter 9. Homeostasis: Active Regulation of the Internal Environment

Follow us on Facebook and Twitter, or subscribe to our mailing list, to receive news updates. Learn more.


Links 1 - 20 of 1828

By Lisa Sanders, M.D. The pain woke the 52-year-old physician from a dead sleep. It was as if all the muscles in his right leg, from those in the buttock down his thigh to the very bottom of his calf, were on fire. He shifted slightly to see if he could find a more comfortable position. There was a jag of pain, and he almost cried out. He glanced at the clock: 4 a.m. In just three hours he would have to get up. He had a full day of patients to see. Massage didn’t help. He couldn’t get comfortable lying flat, so finally he moved to the living room, to a recliner. Only then, and only by lying completely still, did he manage to get the pain to abate. He drifted off, but never for long. The searing pain in his leg and buttock slowly eased, and by the time his alarm went off, he could stand and walk — though his muscles still ached and he had to baby his right leg, causing a limp. Between patients, he arranged to see his own doctor. He’d had pain off and on in his buttocks, one side or the other, for more than a year. The pain was in the middle of each cheek and was worse when he was sitting and at the end of the day. Walking to and from his car on the way home was brutal. And then, as mysteriously as it came, it would disappear — only to come back a week or two later. When he first told his doctor about his pain, the exam didn’t show much. He was a little tender at the bottom of the bones you sit on, called the ischia. His doctor thought it was ischial bursitis. Between the tips of the ischia and the largest muscles of the buttocks, there are little pads called bursae. Sometimes these pads become inflamed. The man’s doctor recommended stretching exercises for the muscles around the bursae. He did them regularly, though he wasn’t sure they helped. The pain he had that night, though, was different, and a whole lot worse. Again, his doctor couldn’t find much. Maybe it was a kind of nerve pain, like sciatica, the patient suggested. The doctor agreed and ordered an M.R.I. to look for a pinched nerve. The result was normal. © 2020 The New York Times Company

Keyword: Pain & Touch; Neuroimmunology
Link ID: 27474 - Posted: 09.16.2020

By Linda Searing If you’re obese, losing just 5 percent of your weight starts you on the path to better health, but new research finds that losing 13 percent of your weight may make a good-size dent in your chances of developing several unhealthy conditions. For instance, the odds of developing Type 2 diabetes were at least 42 percent lower among obese people who lost that much weight than for those who did not lose weight, according to a report from the European and International Congress on Obesity. The research was based on eight years of data on 552,953 middle-aged adults who were obese and intentionally lost weight (meaning their weight loss did not occur because of an illness). Besides the diabetes effect, losing 13 percent of their weight also made people 25 percent less likely to develop high blood pressure or sleep apnea, and it correlated to a 22 percent risk reduction for high cholesterol and a 20 percent lower risk for osteoarthritis. Obesity, defined as excessive fat accumulation that presents a risk to health, is often determined by a person’s body mass index (BMI), a calculation of body fatness based on weight and height. The simplest way to figure your BMI is to plug your height and weight into an online calculator. A BMI of 30 or above is considered obese. Treatment for obesity usually starts with a modest weight-loss goal of 5 to 10 percent (10 to 20 pounds for someone weighing 200) and includes a change in eating habits and an increase in physical activity.

Keyword: Obesity
Link ID: 27470 - Posted: 09.14.2020

Primatologists observed that different groups of bonobos have different dietary preferences — indicating a form of "culture" among the animals. AILSA CHANG, HOST: Bonobos, like chimpanzees, are one of our closest living relatives. We share about 99% of our DNA. These endangered apes are covered in incredibly black hair. LIRAN SAMUNI: And what's very nice is that they have extremely pink lips, almost as if they put the lipstick on. SACHA PFEIFFER, HOST: That's Liran Samuni, a primatologist at Harvard University. Now her team has discovered that wild bonobos share more than just DNA with humans and chimps. They also appear to share our penchant for culture. SAMUNI: We already had some information about chimpanzees that they have the ability for culture. But it was always this kind of a puzzle about bonobos. CHANG: So for more than four years, the researchers tracked two bonobo groups in the Democratic Republic of Congo, documenting the apes' social interactions and what they hunted. And they found a striking dietary difference. SAMUNI: So we had one group which specialized on the hunting of a small antelope called duiker, while the other bonobo group specialized on the hunting of anomalure, which is a gliding rodent. PFEIFFER: Samuni says think about it in the context of humans. You might have two cultures living near or among each other, but one prefers chicken; the other prefers beef. CHANG: Samuni's colleague at Harvard Martin Surbeck says that's important because it shows that the two groups of bonobos have different preferences despite their overlapping range. © 2020 npr

Keyword: Evolution
Link ID: 27465 - Posted: 09.12.2020

By Veronique Greenwood Hummingbirds live a life of extremes. The flitting creatures famously have the fastest metabolisms among vertebrates, and to fuel their zippy lifestyle, they sometimes drink their own body weight in nectar each day. But the hummingbirds of the Andes in South America take that extreme lifestyle a step further. Not only must they work even harder to hover at altitude, but during chilly nights, they save energy by going into exceptionally deep torpor, a physiological state similar to hibernation in which their body temperature falls by as much as 50 degrees Fahrenheit. Then, as dawn approaches, they start to shiver, sending their temperatures rocketing back up to 96 degrees. It’s an intense process, says Andrew McKechnie, a professor of zoology at the University of Pretoria in South Africa. “You’ve got a bird perching on a branch, whose body temp might be 20 degrees Celsius,” or 68 Fahrenheit, he said. “And it’s cranking out the same amount of heat as when it is hovering in front of a flower.” Now, Dr. McKechnie and colleagues reported on Wednesday in Biology Letters that the body temperatures of Andean hummingbirds in torpor and the amount of time they spend in this suspended animation vary among species, with one particular set of species, particularly numerous in the Andes, tending to get colder and go longer than others. They also report one of the lowest body temperatures ever seen in hummingbirds: just under 38 degrees Fahrenheit. On a trip to the Andes about five years ago, Blair Wolf, a professor of biology at the University of New Mexico and an author of the new paper, and his colleagues captured 26 of the little birds for overnight observation. They measured the hummingbirds’ body temperatures as they roosted for the night and found that almost all of them entered torpor, showing a steep decline in temperature partway through the night. © 2020 The New York Times Company

Keyword: Sleep; Miscellaneous
Link ID: 27463 - Posted: 09.09.2020

By Nicholas Bakalar Being overweight may be linked to an increased risk for dementia. British researchers used data on 6,582 men and women, age 50 and older, who were cognitively healthy at the start of the study. The analysis, in the International Journal of Epidemiology, tracked the population for an average of 11 years, recording incidents of physician-diagnosed dementia. Almost 7 percent of the group developed dementia. Compared with people of normal weight (body mass index between 18.5 and 24.9), overweight people with a B.M.I. of 25 to 29.9 were 27 percent more likely to develop dementia, and the obese, with a B.M.I. of 30 or higher, were 31 percent more likely to become demented. The researchers also found that women with central obesity — a waist size larger than 34.6 inches — were 39 percent more likely to develop dementia than those with normal waist size. Fat around the middle was not associated with a higher dementia risk in men. The study controlled for age, sex, APOE4 (a gene known to increase the risk of Alzheimer’s disease, the most common form of dementia), education, marital status, smoking and other known dementia risks. The lead author, Yixuan Ma, a student at University College London, said that this observational study does not prove cause and effect. “Being overweight is just a risk,” she said. “It doesn’t mean that an overweight person will necessarily get dementia. But for many reasons, it’s good to maintain a normal weight and engage in vigorous physical activity over a lifetime.” © 2020 The New York Times Company

Keyword: Alzheimers; Obesity
Link ID: 27449 - Posted: 09.05.2020

By Michelle Konstantinovsky Rosey has lived with bulimia for more than a decade. The 31-year-old resident of Melbourne, Australia, started therapy for her eating disorder six years ago. Although she says she had never considered herself “cured,” she had reached a point in her recovery that felt hopeful and manageable. Then along came the novel coronavirus. When mandatory COVID-19 lockdowns began in Australia in March, Rosey’s anxiety went into overdrive. “I’m single, I live alone, my family lives in another state, and I’m not able to see friends,” she says, adding that her need for control—something she has now lost in almost every area of her life—has played a major role in the resurgence of symptoms: “To have everything I knew and had control over, including how I managed my illness, ripped away has been one of the hardest things.” Rosey is living an experience that may be familiar to anyone dealing with an eating disorder while weathering the unexpected storms of 2020. Recent research indicates that pandemic-related stay-at-home orders have ramped up anorexia, bulimia and binge-eating disorder symptoms. A study published last month in the International Journal of Eating Disorders revealed that during the first few months of the pandemic, many individuals with anorexia reported restricting their eating more. Meanwhile others with bulimia and binge-eating disorder reported more bingeing urges and episodes. Respondents also noted increased anxiety and concern about COVID-19’s impact on their mental health. More than one third of the 1,021 participants (511 in the U.S. and 510 in the Netherlands) said their eating disorder had worsened—and they attributed this change to issues such as a lack of structure, a triggering environment, the absence of social support and an inability to obtain foods that fit their meal plans. © 2020 Scientific American,

Keyword: Anorexia & Bulimia; Stress
Link ID: 27439 - Posted: 08.29.2020

By Anahad O’Connor Artificial sweeteners hold the promise of satisfying your sweet tooth without the downside of excess calories, and they are increasingly used in products ranging from diet sodas and powdered drink mixes to yogurt and baked goods. But whether using them can prevent weight gain — a problem many people are struggling with during the coronavirus lockdowns — has long been an open question. Now some studies are providing answers. Researchers have found that artificial sweeteners can be useful as a tool to help people kick their sugar habits, and that for some people, replacing sugar with nonnutritive sweeteners can indeed help stave off weight gain. But they can also have effects on hormones, blood sugar and other aspects of metabolism that some experts say are concerning, and they caution against consuming them routinely for long periods of time. “The idea we need to get rid of is that because they have zero calories they have zero metabolic effects,” said Marta Yanina Pepino, an assistant professor in the department of food science and human nutrition at the University of Illinois at Urbana-Champaign. “Our data suggests that they are metabolically active, and depending on how frequently you use them, some people can see more effects than others.” Purchases of foods and beverages containing sugar substitutes have risen as health-conscious consumers cut back on sugar. Diet beverages account for the largest source of these sweeteners in the American diet. Among the most popular sugar substitutes are sucralose, also known as Splenda, and aspartame, which is found in Diet Coke, Diet Pepsi and thousands of other foods. Stevia, a zero-calorie plant extract that is marketed as natural, is also widely used in many products as a sugar substitute. In a report published recently in the Journal of the American Heart Association, researchers at Boston Children’s Hospital studied what happened when soda drinkers switched to drinking water or beverages that were artificially sweetened. The researchers recruited 203 adults who consumed at least one sugary beverage daily; only some of them were overweight. © 2020 The New York Times Company

Keyword: Obesity
Link ID: 27429 - Posted: 08.22.2020

By Priyanka Runwal Everyone needs to cool off on a scorching summer day, even chimpanzees. Where do the primates go on sizzling days when woodlands and forests don’t provide respite from the heat? But not just any chimps. New research shows that on Senegal’s savannas, home to a population of chimpanzees that has long fascinated scientists for their distinct behaviors, you’re more likely to find mama chimps than adult males or non-lactating females hiding out in cool caves. Their visits coincided with the hottest times of day and became more frequent during the hottest months of the year, according to the study published last month in the International Journal of Primatology. They also made these visits despite the risks of encounters with predators, showing how important the locations are for helping them survive and bring up babies in a challenging landscape that is threatened by human activities. In southeastern Senegal, temperatures spike to 110 degrees Fahrenheit and fires burn large parts of the landscape over a seven-month dry season. Several natural cave formations pock the terrain, and they can be up to 55 degrees cooler than the surrounding grasslands. The region is also home to the northernmost population of western chimpanzees, a critically endangered subspecies that mostly lives in large swathes of open grasslands and woodlands in this area. In 2001, Jill Pruetz, a primatologist then at Iowa State University, gathered evidence of western chimpanzees using caves in the area, suspecting that they used them to escape the heat and possibly avoid heat stroke and other ill health effects of the dry season. But she reached few conclusions about whether all of the chimps used the caves as often as others. Kelly Boyer Ontl, a primatologist at Ball State University in Indiana and lead author of the new study, said, “I was really interested in finding out what chimpanzees are doing in caves, when are they using it and who’s going in there.” © 2020 The New York Times Company

Keyword: Evolution
Link ID: 27409 - Posted: 08.08.2020

Obesity should be defined by a person's health - not just their weight, says a new Canadian clinical guideline. It also advises doctors to go beyond simply recommending diet and exercise. Instead, they should focus on the root causes of weight gain and take a holistic approach to health. The guideline, which was published in the Canadian Medical Association Journal on Tuesday, specifically admonished weight-related stigma against patients in the health system. "The dominant cultural narrative regarding obesity fuels assumptions about personal irresponsibility and lack of willpower and casts blame and shame upon people living with obesity," the guideline, which is intended to be used by primary care physicians in diagnosing and treating obesity in their daily practice, states. Ximena Ramos-Salas, the director of research and policy at Obesity Canada and one of the guideline's authors, said research shows many doctors discriminate against obese patients, and that can lead to worse health outcomes irrespective of their weight. "Weight bias is not just about believing the wrong thing about obesity," she told the BBC. "Weight bias actually has an effect on the behaviour of healthcare practitioners." The rate of obesity has tripled over the past three decades in Canada, and now about one in four Canadians is obese according to Statistics Canada. The guideline had not been updated since 2006. The new version was funded by Obesity Canada, the Canadian Association of Bariatric Physicians and Surgeons and the Canadian Institutes of Health Research through a Strategy for Patient-Oriented Research grant. Although the latest advice still recommends using diagnostic criteria like the body mass index (BMI) and waist circumference, it acknowledges their clinical limitations and says doctors should focus more on how weight impacts a person's health. Small reductions in weight, of about 3-5%, can lead to health improvements and an obese person's "best weight" might not be their "ideal weight" according to BMI, the guideline says. It emphasises that obesity is a complex, chronic condition that needs lifelong management. © 2020 BBC.

Keyword: Obesity
Link ID: 27400 - Posted: 08.06.2020

By Jane E. Brody Appearances, as I’m sure you know, can be deceiving. In one all-too-common example, adolescents and young adults with disordered eating habits or outright eating disorders often go unrecognized by both parents and physicians because their appearance defies common beliefs: they don’t look like they have an eating problem. One such belief is that people with anorexia always look scrawny and malnourished when in fact they may be of normal weight or even overweight, according to recent research at the University of California, San Francisco. The researchers, led by Dr. Jason M. Nagata, a specialist in adolescent medicine at the university’s Benioff Children’s Hospital, found in a national survey that distorted eating behaviors occur in young people irrespective of their weight, gender, race, ethnicity or sexual orientation. And it’s not just about losing weight. The survey revealed that among young adults aged 18 to 24, 22 percent of males and 5 percent of females were striving to gain weight or build muscle by relying on eating habits that may appear to be healthy but that the researchers categorized as risky. These practices include overconsuming protein and avoiding fats and carbohydrates. The use of poorly tested dietary supplements and anabolic steroids was also common among those surveyed. The Covid-19 pandemic has likely exacerbated the problem for many teenagers whose daily routines have been disrupted and who now find themselves at home all day with lots of food being hoarded in kitchens and pantries, Dr. Nagata said in an interview. “We’re seeing more patients and referrals for eating disorders and their complications,” he said. © 2020 The New York Times Company

Keyword: Anorexia & Bulimia
Link ID: 27389 - Posted: 07.29.2020

Laura P.W. Ranum An FDA-approved diabetes drug shows early signs of promise against the most common genetic form of amyotrophic lateral sclerosis, a devastating neurological condition that causes paralysis. ALS is a progressive disease that affects neurons in the brain and spinal cord. Motor neurons transmit signals from our brain to our muscles and allow us to move. ALS causes these motor neurons to die, resulting in the loss of a patient’s ability to speak, eat, move and breathe. Notable ALS patients include New York Yankees baseball star Lou Gehrig (the disease is often called Lou Gehrig’s disease), physicist Stephen Hawking and New Orleans Saints football star Steve Gleason. There are currently more than 30,000 cases of ALS in the United States, and life expectancy after diagnosis is typically 2 to 5 years. There is currently no cure for ALS. I am a scientist who studies neurological diseases that run in families, and I have been working hard to find a treatment to stop ALS. Our team has made a discovery, detailed in a scientific study, that paves the way for further research for improving disease in a genetic type of ALS caused by a mutation in a gene with the unwieldy name chromosome 9 open reading frame 72 (C9orf72), based on its location on chromosome 9. In addition to ALS, mutations in this gene can also cause frontotemporal dementia, which can cause apathy, loss of emotional control and cognitive decline. Some patients with the C9orf72 mutation develop ALS, others develop frontotemporal dementia and some develop both. Together, these diseases are referred to here as C9-ALS/FTD. I have been focusing on C9-ALS, which is the most common genetic type of ALS which is caused by a mutation in the C9orf72 gene. The mutation occurs when six letters of DNA that make up part of the gene’s genetic code – GGGGCC – are repeated hundreds of extra times. It is as if a single word is repeated hundreds of times in the same sentence. © 2010–2020, The Conversation US, Inc.

Keyword: ALS-Lou Gehrig's Disease
Link ID: 27379 - Posted: 07.21.2020

By Lisa Sanders, M.D. The early-morning light wakened the middle-aged man early on a Saturday morning in 2003. He felt his 51-year-old wife move behind him and turned to see her whole body jerking erratically. He was a physician, a psychiatrist, and knew immediately that she was having a seizure. He grabbed his phone and dialed 911. His healthy, active wife had never had a seizure before. But this was only the most recent strange episode his wife had been through over the past 18 months. A year and a half earlier, the man returned to his suburban Pittsburgh home after a day of seeing patients and found his wife sitting in the kitchen, her hair soaking wet. He asked if she had just taken a shower. No, she answered vaguely, without offering anything more. Before he could ask her why she was so sweaty, their teenage son voiced his own observations. Earlier that day, the boy reported, “She wasn’t making any sense.” That wasn’t like her. Weeks later, his daughter reported that when she arrived home from school, she heard a banging sound in a room in the attic. She found her mother under a futon bed, trying to sit up and hitting her head on the wooden slats underneath. Her mother said she was looking for something, but she was obviously confused. The daughter helped her mother up and brought her some juice, which seemed to help. With both episodes, the children reported that their mother didn’t seem upset or distressed. The woman, who had trained as a psychiatrist before giving up her practice to stay with the kids, had no recollection of these odd events. The Problem Is Sugar Her husband persuaded her to see her primary-care doctor. Upon hearing about these strange spells, the physician said she suspected that her patient was having episodes of hypoglycemia. Very low blood sugar sends the body into a panicked mode of profuse sweating, shaking, weakness and, in severe cases, confusion. She referred her to a local endocrinologist. © 2020 The New York Times Company

Keyword: Epilepsy
Link ID: 27341 - Posted: 07.02.2020

By Abigail Zuger, M.D. Do I dare to eat a Cheeto? I do not; I can’t even let one into the house. The same goes for its delectably plump twin, the Cheez Doodle; its tasty rotund cousin, the Cheez Ball; and its heavenly brother by another mother, that sandwich of two Cheezy crackers glued together with peanut butter. I dare not even walk down the supermarket aisle where this neon orange family lives, for while others may succumb to chocolate or pastry, my Waterloo is this cheesy goodness — let’s call it Cheez. One Cheez Doodle would lead to a bag, then to more bags, and then to the certain catastrophe of a larger, sicker me. I know these delicacies are terrible for a person’s health. How exactly do I know that? It’s not because I’m a medical professional, that’s for sure; there were zero discussions of Cheez in our pre- or post-graduate training. I know because I just know, is all. Overprocessed chemical-laden stuff is bad for you; it’s pure malevolent junk. Everyone knows that. George Zaidan, an MIT-trained chemist of contrarian bent, knows it too. That is, he knows it to be piously reiterated received wisdom, and thus legitimate fodder for dissection, examination, refutation, and cheerfully self-indulgent obscenity-laden riffs. Further, he has chosen this junk food truth as an excellent starting point for “Ingredients: The Strange Chemistry of What We Put in Us and On Us,” an entertaining and enlightening jaunt around the perimeters of exactly what we can ever hope science can teach us about stuff that is good and bad for us. And it all begins with a single Cheeto, the putative first brick on the winding golden road to nutritional hell.

Keyword: Obesity
Link ID: 27329 - Posted: 06.27.2020

By Susan Burton “Diet” is a strange word, used to describe both a deviation from the norm and the norm itself: the foods that make up a day, a week, a lifetime. From the beginning, my diet was a big part of my story, even the one that others told about me. “All babies like rice cereal,” my mother will say. “But you didn’t.” In the high chair, I would tighten my lips and turn away. When I was two, at the first preschool parent-teacher conference, they told my mother, “Susan never eats snack.” Recalling encounters with foods I disliked as a small child raises an old alarm in me. A sip of a soda at the zoo one afternoon, the prickling shock of the bubbles. It would be more than a decade before I would try something fizzy again. Melba toast at a white-tablecloth restaurant in Chicago. The next day, I vomited. The bright yellow worm of mustard on a hot dog at a public beach. The jagged chopped nuts on a hot-fudge sundae, even though I’d asked for it plain. In any choice related to food, I always preferred plain. I went through primary school never eating a salad or a single bite of fruit. The term “picky eater” didn’t apply to me. Picky eaters had to be reminded to pay attention to their plates. But I never forgot about food, in the way you never forget about anything you fear. I was scared of feeling sick. I was scared of not liking tastes. I was scared of something getting in me that I could never get out. I was scared of something happening to my body that would make me not me. In many ways, my adolescence was stereotypical. I was an awkward middle-schooler who transformed herself with the help of Seventeen magazine. I stood in bleachers at Friday-night football games. I read Sylvia Plath and wrote furiously in my journal. I learned to smoke cigarettes on a weekday afternoon in a wood-panelled car. I signed the notes I passed in class “Love, Susan.” I tried to be the perfect teen-age girl. But I was also a troubled one, and the dark part of my adolescence became its heart. © 2020 Condé Nast.

Keyword: Anorexia & Bulimia
Link ID: 27306 - Posted: 06.17.2020

Natalie Dombois for Quanta Magazine It’s not surprising that the fruit fly larva in the laboratory of Jimena Berni crawls across its large plate of agar in search of food. “A Drosophila larva is either eating or not eating, and if it’s not eating, it wants to eat,” she said. The surprise is that this larva can search for food at all. Owing to a suite of genetic tricks performed by Berni, it has no functional brain. In fact, the systems that normally relay sensations of touch and feedback from its muscles have also been shut down. Berni, an Argentinian neuroscientist whose investigations of fruit fly nervous systems recently earned her a group leader position at the University of Sussex, is learning what the tiny cluster of neurons that directly controls the larva’s muscles does when it’s allowed to run free, entirely without input from the brain or senses. How does the animal forage when it’s cut off from information about the outside world? The answer is that it moves according to a very particular pattern of random movements, a finding that thrilled Berni and her collaborator David Sims, a professor of marine ecology at the Marine Biological Association in Plymouth, U.K. For in its prowl for food, this insensate maggot behaves exactly like an animal Sims has studied for more than 25 years — a shark. In neuroscience, the usual schema for considering behavior has it that the brain receives inputs, combines them with stored information, then decides what to do next. This corresponds to our own intuitions and experiences, because we humans are almost always responding to what we sense and remember. But for many creatures, useful information isn’t always available, and for them something else may also be going on. When searching their environment, sharks and a diverse array of other species, now including fruit fly larvae, sometimes default to the same pattern of movement, a specific type of random motion called a Lévy walk. All Rights Reserved © 2020

Keyword: Learning & Memory; Aggression
Link ID: 27301 - Posted: 06.13.2020

Ruth Williams Research teams in the US and Japan have each discovered independently and by unrelated routes a population of hypothalamic neurons in mice that induce the low body temperature, reduced metabolism, and inactivity characteristic of hibernation and torpor. The two papers are published today (June 11) in Nature. “Trying to pin down which neurons are involved with initiating torpor and hibernation . . . is certainly something that biologists have been interested in for several years now,” says biologist Steven Swoap of Williams College who was not involved in the research. “Both of [the teams] come at it from a different angle and almost end up in the same place, so they complement each other in that way, which is pretty nice,” he adds. Hibernation and daily torpor are both forms of mammalian suspended animation and share a number of features. Both involve significant, but regulated, drops in body temperature, metabolism, heart rate, breathing rate, and activity, and both are thought to be ways of preserving energy when food is scarce. While hibernation lasts for weeks or months, however, daily torpor lasts several hours each day. Why some mammals such as bears and certain primates and rodents have the ability to enter periods of dormancy while others don’t is unknown. But the diversity of hibernator species suggests that the biological mechanisms controlling such states may also be preserved, albeit unused, in non-hibernating species. This tantalizing possibility sparks ideas of sending dormant astronauts on extended space journeys as well as more down-to-earth notions of temporarily lowering body temperature and metabolism to preserve tissues in patients with, for example, traumatic injuries. © 1986–2020 The Scientist.

Keyword: Sleep
Link ID: 27300 - Posted: 06.13.2020

By David Templeton For much of the 20th century, most people thought that stress caused stomach ulcers. But that belief was largely dismissed 38 years ago when a study, which led to a Nobel Prize in 2016, described the bacterium that generates inflammation in the gastrointestinal tract and causes peptic ulcers and gastritis. “The history of the idea that stress causes ulcers took a side step with the discovery of Helicobacter pylori,” said Dr. David Levinthal, director of the University of Pittsburgh Neurogastroenterology & Motility Center. “For the longest time — most of the 20th century — the dominant idea was that stress was the cause of ulcers until the early 1980s with discovery of Helicobacter pylori that was tightly linked to the risk of ulcers. That discovery was critical but maybe over-generalized as the only cause of ulcers.” Now in an important world first, a study co-authored by Levinthal and Peter Strick, both from the Pitt School of Medicine, has explained what parts of the brain’s cerebral cortex influence stomach function and how it can affect health. “Our study shows that the activity of neurons in the cerebral cortex, the site of conscious mental function, can impact the ability of bacteria to colonize the stomach and make the person more sensitive to it or more likely to harbor the bacteria,” Levinthal said. The study goes far beyond ulcers by also providing evidence against the longstanding belief that the brain’s influence on the stomach was more reflexive and with limited, if any, involvement of the thinking brain. And for the first time, the study also provides a general blueprint of neural wiring that controls the gastrointestinal tract. © 2020 StarTribune.

Keyword: Obesity
Link ID: 27286 - Posted: 06.06.2020

In a nationwide study, NIH funded researchers found that the presence of abnormal bundles of brittle blood vessels in the brain or spinal cord, called cavernous angiomas (CA), are linked to the composition of a person’s gut bacteria. Also known as cerebral cavernous malformations, these lesions which contain slow moving or stagnant blood, can often cause hemorrhagic strokes, seizures, or headaches. Current treatment involves surgical removal of lesions when it is safe to do so. Previous studies in mice and a small number of patients suggested a link between CA and gut bacteria. This study is the first to examine the role the gut microbiome may play in a larger population of CA patients. Led by scientists at the University of Chicago, the researchers used advanced genomic analysis techniques to compare stool samples from 122 people who had at least one CA as seen on brain scans, with those from age- and sex-matched, control non-CA participants, including samples collected through the American Gut Project(link is external). Initially, they found that on average the CA patients had more gram-negative bacteria whereas the controls had more gram-positive bacteria, and that the relative abundance of three gut bacterial species distinguished CA patients from controls regardless of a person’s sex, geographic location, or genetic predisposition to the disease. Moreover, gut bacteria from the CA patients appeared to produce more lipopolysaccharide molecules which have been shown to drive CA formation in mice. According to the authors, these results provided the first demonstration in humans of a “permissive microbiome” associated with the formation of neurovascular lesions in the brain.

Keyword: Stroke
Link ID: 27280 - Posted: 06.04.2020

Ruth Williams Experiments in mice and observations in humans have suggested the bone protein osteocalcin acts as a hormone regulating, among other things, metabolism, fertility, exercise capacity and acute stress. That interpretation is now partially in doubt. Two independent papers published yesterday (May 28) in PLOS Genetics, each of which presents a new osteocalcin knockout mouse strain, report that glucose metabolism and fertility were unaffected in the animals. While some researchers praise the studies, others highlight weaknesses. “I thought they were very good papers. I think the authors should be congratulated for very comprehensive studies of both skeletal and extraskeletal functions of osteocalcin,” says emeritus bone researcher Caren Gundberg of Yale School of Medicine who was not involved in the research. Skeletal biologist Gerard Karsenty of Columbia University disagrees. “There have been 25 laboratories in the world . . . that have shown osteocalcin is a hormone,” says Karsenty. These two papers “do not affect the work of [those] groups,” he adds, “because they are . . . technically flawed.” This tiny protein, one of the most abundant in the body, is produced and secreted by bone-forming osteoblast cells. In the 40 or so years since osteocalcin’s discovery, its precise function, or functions—whether in the bone or endocrine system—have not been fully pinned down. Studies from Karsenty’s lab more than 10 years ago were the first to indicate that osteocalcin could act as a hormone, regulating glucose metabolism. But the suggested hormonal function has been questioned for its relevance to humans. For example, while studies in people have shown that levels of osteocalcin in the blood are correlated with diabetes, whether this is a cause or effect is unclear. © 1986–2020 The Scientist.

Keyword: Hormones & Behavior; Obesity
Link ID: 27275 - Posted: 06.03.2020

By Nicholas Bakalar Eating foods high in flavonoids — a group of nutrients found in many fruits and vegetables — may lower your risk for dementia, researchers report. The study, in the American Journal of Clinical Nutrition, looked at 2,801 men and women who were 50 and older and free of dementia at the start. Over an average of 20 years of follow-up, researchers gathered diet information at five periodic health examinations; during that time, 193 of the participants developed Alzheimer’s disease or other forms of dementia. Compared with those in the 15th percentile or lower for flavonoid intake, those in the 60th or higher had a 42 to 68 percent lower risk for dementia, depending on the type of flavonoid consumed. Intake of one type of flavonoid, anthocyanins, abundant in blueberries, strawberries and red wine, had the strongest association with lowered risk. Apples, pears, oranges, bananas and tea also contributed. The study controlled for many health and behavioral characteristics, including how strongly participants adhered to the government’s Dietary Guidelines for Americans, which in addition to fruits and vegetables emphasize whole grains, lean meats and other heart-healthy foods. The senior author, Paul F. Jacques, a scientist with the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, said that the amount consumed by those who benefited the most was not large. Their monthly average was about seven half-cup servings of strawberries or blueberries, eight apples or pears, and 17 cups of tea. “It doesn’t take much,” he said. “A couple of servings of berries a week, maybe an apple or two.” © 2020 The New York Times Company

Keyword: Alzheimers
Link ID: 27255 - Posted: 05.20.2020