Archive for January 2010
Many of the health benefits of aerobic exercise are due to the most recent exercise session (rather than weeks, months and even years of exercise training), and the nature of these benefits can be greatly affected by the food we eat afterwards, according to a study published in the Journal of Applied Physiology (http://jap.physiology.org).
“Differences in what you eat after exercise produce different effects on the body’s metabolism,” said the study’s senior author, Jeffrey F. Horowitz of the University of Michigan. This study follows up on several previous studies that demonstrate that many health benefits of exercise are transient: one exercise session produces benefits to the body that taper off, generally within hours or a few days. Read the rest of this entry »
Investigators at Sanford-Burnham Medical Research Institute (Sanford-Burnham) have discovered a new way the cell surface protein, CD44, helps specific T helper (Th1) cells develop immunologic memory. Linda Bradley, Ph.D., Bas Baaten, Ph.D., and colleagues determined that without CD44, Th1 cells died off during their initial immune response and were unable to generate immunologic memory. This is the first time scientists have identified this unique CD44 function on Th1 cells, making the protein a potential target to treat a variety of diseases. The study was published online on January 14 in the journal Immunity. Read the rest of this entry »
The antiaging power of blood might not be just the stuff of vampire stories. According to new research from Harvard University, an unspecified factor in the blood of young mice can reverse signs of aging in the circulatory system of older ones. It’s not yet clear how these changes affect the animals’ overall health or longevity. But the research provides hope that some aspects of aging, such as the age-related decline in the ability to fight infection, might be avoidable. Read the rest of this entry »
Posted January 30, 2010on:
Ever since Cicero’s De Natura Deorum ii.34., humans have been intrigued by the origin and mechanisms underlying complexity in nature. Darwin suggested that adaptation and complexity could evolve by natural selection acting successively on numerous small, heritable modifications. But is this enough? Here, we describe selected studies of experimental evolution with robots to illustrate how the process of natural selection can lead to the evolution of complex traits such as adaptive behaviours. Just a few hundred generations of selection are sufficient to allow robots to evolve collision-free movement, homing, sophisticated predator versus prey strategies, coadaptation of brains and bodies, cooperation, and even altruism. In all cases this occurred via selection in robots controlled by a simple neural network, which mutated randomly
Children exposed in the womb to chemicals in cosmetics and fragrances are more likely to develop behavioral problems commonly found in children with attention deficit disorders, according to a study of New York City school-age children published Thursday.
Scientists at Mount Sinai School of Medicine reported that mothers who had high levels of phthalates during their pregnancies were more likely to have children with poorer scores in the areas of attention, aggression and conduct.
Children were 2.5 times more likely to have attention problems that were “clinically significant” if their mothers were among those highest exposed to phthalates, the study found. The types of behavior that increased are found in children with Attention Deficit Hyperactivity Disorder and other so-called disruptive behavior disorders.
C. elegans, a tiny worm about a millimeter long, doesn’t have much of a brain, but it has a nervous system — one that comprises 302 nerve cells, or neurons, to be exact. In the 1970s, a team of researchers at Cambridge University decided to create a complete “wiring diagram” of how each of those neurons are connected to one another. Such wiring diagrams have recently been christened “connectomes,” drawing on their similarity to the genome, the total DNA sequence of an organism. The C. elegans connectome, reported in 1986, took more than a dozen years of tedious labor to find.
Now a handful of researchers scattered across the globe are tackling a much more ambitious project: to find connectomes of brains more like our own. The scientists, including several at MIT, are working on technologies needed to accelerate the slow and laborious process that the C. elegans researchers originally applied to worms. With these technologies, they intend to map the connectomes of our animal cousins, and eventually perhaps even those of humans. Their results could fundamentally alter our understanding of the brain.
via Mapping the brain.
People with atrial fibrillation, a common type of irregular heartbeat, should be referred for a surgical treatment called catheter ablation if an oral medication is not effective, said the authors of a study released Tuesday.
In a head-to-head comparison of the two forms of treatment, catheter ablation was so superior in resolving the disorder and helping patients to feel better that the study was halted early. The results will be published today in the Journal of the American Medical Assn.
Atrial fibrillation, which affects more than 2 million Americans, occurs when the heart’s two small upper chambers quiver instead of beating effectively. It can cause blood to pool and clot, raising the risk of a stroke. The condition can go undetected indefinitely, though many people have symptoms such as palpitations, dizziness, chest pain, fatigue and shortness of breath. Once considered a nuisance, the condition is now recognized as a potential precursor to stroke that should be treated.
Skin cells called fibroblasts can be transformed into neurons quickly and efficiently with just a few genetic tweaks, according to new research. The surprisingly simple conversion, which doesn’t require the cells to be returned to an embryonic state, suggests that differentiated adult cells are much more flexible than previously thought.
Cellular transformation: A cocktail of three genes can transform skin cells into neurons (shown here in red).
Credit: Thomas Vierbuchen
If the research, published in the journal Nature yesterday, can be repeated in human cells, it would provide an easier method for generating replacement neurons from individual patients. Brain cells derived from a skin graft would be genetically identical to the patient and therefore remove the risk of immune rejection–such an approach might one day be used to treat Parkinson’s or other neurodegenerative diseases.
“It’s almost scary to see how flexible these cell fates are,” says Marius Wernig, a biologist at the Institute for Stem Cell Biology and Regenerative Medicine at Stanford, who led the research. “You just need a few factors, and within four to five days you see signs of neuronal properties in these cells.”
New research finds that an increase in brain magnesium improves learning and memory in young and old rats. The study, published by Cell Press in the January 28th issue of the journal Neuron, suggests that increasing magnesium intake may be a valid strategy to enhance cognitive abilities and supports speculation that inadequate levels of magnesium impair cognitive function, leading to faster deterioration of memory in aging humans.
Diet can have a significant impact on cognitive capacity. Identification of dietary factors which have a positive influence on synapses, the sites of communication between neurons, might help to enhance learning and memory and prevent their decline with age and disease. Read the rest of this entry »
By combining a research technique that dates back 136 years with modern molecular genetics, a Johns Hopkins neuroscientist has been able to see how a mammal’s brain shrewdly revisits and reuses the same molecular cues to control the complex design of its circuits.
Details of the observation in lab mice, published Dec. 24 in Nature, reveal that semaphorin, a protein found in the developing nervous system that guides filament-like processes, called axons, from nerve cells to their appropriate targets during embryonic life, apparently assumes an entirely different role later on, once axons reach their targets. In postnatal development and adulthood, semaphorins appear to be regulating the creation of synapses — those connections that chemically link nerve cells.
People profoundly deficient in human growth hormone (HGH) due to a genetic mutation appear to live just as long as people who make normal amounts of the hormone, a new study shows. The findings suggest that HGH may not be the “fountain of youth” that some researchers have suggested.
“Without HGH, these people still live long, healthy lives, and our results don’t seem to support the notion that lack of HGH slows or accelerates the aging process,” says Roberto Salvatori, M.D.,associate professor in the Department of Endocrinology at the Johns Hopkins University School of Medicine.
The researchers, working with an unusual population of dwarves residing in Itabaianinha county, a rural area in the northeastern Brazilian state of Sergipe, and led by Salvatori, sought to sort out conflicting results of previous studies on the effects of HGH on human aging. Read the rest of this entry »
Ever since RNA interference was discovered, in 1998, scientists have been pursuing the tantalizing ability to shut off any gene in the body — in particular, malfunctioning genes that cause diseases such as cancer.
This week, researchers at MIT and Alnylam Pharmaceuticals report that they have successfully used RNA interference to turn off multiple genes in the livers of mice, an advance that could lead to new treatments for diseases of the liver and other organs.
The new delivery method, described in the Proceedings of the National Academy of Sciences, is orders of magnitude more effective than previous methods, says Daniel Anderson, senior author of the paper and a biomedical engineer at the David H. Koch Institute for Integrative Cancer Research at MIT. It’s also the first method that can deliver as many as five genes — previous delivery vehicles could carry only one or two genes.
Learning and memory — abilities associated with a brain or, at the very least, neuronal activity — have been observed in protoplasmic slime, a unicellular organism with multiple nuclei.
When the amoeba Physarum polycephalum is subjected to a series of shocks at regular intervals, it learns the pattern and changes its behaviour in anticipation of the next one to come1, according to a team of researchers in Japan. Remarkably, this memory stays in the slime mould for hours, even when the shocks themselves stop. A single renewed shock after a ‘silent’ period will leave the mould expecting another to follow in the rhythm it learned previously. Toshiyuki Nakagaki of Hokkaido University in Sapporo and his colleagues say that their findings “hint at the cellular origins of primitive intelligence”.
Slime moulds demonstrate primitive learning and memory.EYE OF SCIENCE/SPL
An efficient new method of making endothelial cells, which give rise to blood vessels, could prove a huge boost for tissue engineering and regenerative medicine. By first finding a way to effectively tag endothelial cells, researchers at Weill Cornell Medical College developed a simple way to increase production of these cells by more than 30-fold. The cells might one day by used to create blood vessels in engineered tissue or administered to patients directly to repair injury after heart attack or stroke, resupplying blood to damaged organs.
“[Eventually], we want to be able to inject slurries of these cells into people who have suffered heart attacks, and allow those tissues to recuperate by renewed blood flow,” says Daylon James, assistant research professor in the department of reproductive medicine at Weill Cornell Medical College, who led the research.
Sex isn’t just good, it’s good for your heart, a new study of men indicates.
Reporting in the American Journal of Cardiology, researchers say they’ve found that men with a low frequency of sexual activity have an increased risk of cardiovascular disease.
Men who reported sexual activity of once a month or less had a higher risk of cardiovascular disease than men who reported having sex twice a week or more, writes study researcher Susan A. Hall, PhD, of the department of epidemiology at the New England Research Institutes.
Previous studies have examined the link between erectile dysfunction (ED) and cardiovascular disease (CVD), but the new study is the first to look at frequency of sexual activity and heart risk independently from ED, the researchers say.
Even with the best of available treatments, over a third of patients with depression may not achieve a satisfactory antidepressant response. Deep brain stimulation (DBS), a form of targeted electrical stimulation in the brain via implanted electrodes, is now undergoing careful testing to determine whether it could play a role in the treatment of patients who have not sufficiently improved during more traditional forms of treatment. Read the rest of this entry »
A low-carbohydrate diet may have health benefits that go beyond weight loss.
A new study shows that a low-carbohydrate diet was equally good as the weight loss drug orlistat (the active ingredient in Alli and Xenical) at helping overweight and obese people lose weight, but people who followed the low-carb diet also experienced a healthy drop in their blood pressure levels.
“I expected the weight loss to be considerable with both therapies but we were surprised to see blood pressure improve so much more with the low-carbohydrate diet than with orlistat,” researcher William S. Yancy, Jr., MD, an associate professor of medicine at Duke University Medical Center, says in a news release. “If people have high blood pressure and a weight problem, a low-carbohydrate diet might be a better option than a weight loss medication.”
Researchers say studies have already shown that the two weight loss methods are effective at promoting weight loss, but it’s the first time the health effects of each have been compared head to head.
Researchers at Hurel Corporation have reached a major milestone in their quest to create a chip to replace skin allergy testing on animals. Working with cosmetics firm L’Oreal, Hurel has developed a working microfluidic portion of the chip. While there is still much work to be done before they have a whole chip ready for commercial use, the researchers say this is a major step toward eliminating allergy testing on animals.
Scientists are reporting the first evidence from human research that blueberries — one of the richest sources of healthful antioxidants and other so-called phytochemicals — improve memory. They said the study establishes a basis for comprehensive human clinical trials to determine whether blueberries really deserve their growing reputation as a memory enhancer.
Bonn researchers have discovered an elementary mechanism which regulates vital immune functions in healthy people. In situations of hunger which mean stress for the body’s cells, the body releases more antimicrobial peptides in order to protect itself. The scientists will publish their results in the journal Nature.
Posted January 24, 2010on:
New video footage of a virus infecting cells is challenging what researchers have long believed about how viruses spread, suggesting that scientists may be able to create new drugs to tackle some viruses.
Previously, viruses were thought to spread by entering a cell, replicating there, and then being released to infect new cells, so that the rate of spread of a virus would be limited by how quickly it could replicate in each cell.
However, a virus called vaccinia spreads in a different and much faster way, according to a new study in the journal Science by researchers from Imperial College London, funded by the Medical Research Council. Read the rest of this entry »
amaican sprinter Usain Bolt’s record-setting performances have unleashed a wave of interest in the ultimate limits to human running speed. A new study published in the Journal of Applied Physiology offers intriguing insights into the biology and perhaps even the future of human running speed.
The newly published evidence identifies the critical variable imposing the biological limit to running speed, and offers an enticing view of how the biological limits might be pushed back beyond the nearly 28 miles per hour speeds achieved by Bolt to speeds of perhaps 35 or even 40 miles per hour. Read the rest of this entry »
Posted January 24, 2010on:
A team of scientists led by Professor Adrian Krainer, Ph.D., of Cold Spring Harbor Laboratory has discovered molecular factors in cancer cells that boost the production of an enzyme that helps alter the cells’ glucose metabolism. The altered metabolic state, called the Warburg effect, promotes extremely rapid cell proliferation and tumor growth.
Last month, Madison, WI-based Cellular Dynamics International (CDI) began shipping heart cells derived from a person’s own stem cells. The cells could be useful to researchers studying everything from the toxicity of new or existing drugs to the electrodynamics of both healthy and diseased cardiac cells.
CDI’s scientists create their heart cells–called iCell Cardiomyocytes–by taking cells from a person’s own blood (or other tissue) and chemically reversing them back to a pluripotent state. This means they are able to grow or can be programmed to grow into any cell in the body.
The science comes from the lab of CDI cofounder and stem-cell pioneer James Thomson of the University of Wisconsin. In 2007, his lab published a study led by postdoc Junying Yu in the journal Science that detailed how to reverse virtually any human cell back to an undifferentiated state known as an induced pluripotent stem cell, or IPS cell. (Japanese physician and geneticist Shinya Yamanaka also created IPS cells from humans and published details in the journal Cell in 2007.)
Cutting U.S. salt intake by just half a teaspoon a day would prevent up to 92,000 deaths, 99,000 heart attacks, and 66,000 strokes — a benefit as big as smoking cessation.
That’s the prediction from computer models that used real clinical data to predict the effects of small reductions in salt intake.
“The [ heart] benefits of reduced salt intake are on par with the benefits of population-wide reductions in tobacco use, obesity, and cholesterol levels,” says Kirsten Bibbins-Domingo, PhD.
Cutting daily salt intake by a half teaspoon — about 3 grams — would not be enough to bring most Americans down to the goal of 3.7 grams a day recommended for about 70% of adults. It wouldn’t even get us down to the 5.8 grams a day recommended for lowest-risk adults.
That’s because the average U.S. man gets about 10.4 grams a day and the average U.S. woman gets about 7.3 grams a day.
But cutting back by 3 grams, or even just 1 gram, would have huge effects across the population, Bibbins-Domingo and colleagues find.
Soaking in more sunlight and drinking more dairy may help you ward off colon cancer.Researchers in Europe have found that people with abundant levels of vitamin D — the so-called sunshine vitamin — have a much lower risk of colon cancer. The findings add to a growing body of evidence that suggest vitamin D may have the power to help prevent colon cancer and possibly even improve survival in those who have the disease. The body makes vitamin D after the skin absorbs some of the suns rays. You can also get vitamin D by consuming certain foods and beverages, such as milk and cereal, which have been fortified with the vitamin, but few foods naturally contain it.
If you are reading this while sitting down, you might want to stand up for moment.A new editorial published in the British Journal of Sports Medicine suggests that people who sit still for prolonged periods of time — such as desk workers or coach potatoes — have a higher risk of disease than those who move a muscle every now and then in a non-exercise manner, such as walking up the stairs to grab a cup of coffee.
Prolonged sitting promotes a lack of whole-body muscle movement, which the Swedish-based researchers say is the more correct way to define sedentary behavior. Many people mistakenly believe the term “sedentary” refers to people who do not exercise. But the research team proposes that sedentary behavior is instead a distinct class of behaviors, unrelated to a lack of exercise, that boost bad health. Behaviors can include habits like TV watching. For example, recent evidence has shown that sitting in front of the TV for hours on end can raise your risk of early death from heart disease. A woman’s risk of metabolic syndrome, a precursor to diabetes and heart disease, jumps 26% for every extra hour she sits in front of the TV, according to one cited study. Whole-body muscular inactivity associated with prolonged sitting has also been strongly linked to obesity and even certain types of cancer.
A new lung cancer drug that disrupts blood vessels within the tumor and inhibits blood flow to it looks promising, say researchers who are slated to report their findings Thursday at a cancer meeting in California.
When added to traditional chemotherapy, the new drug, called vadimezan and also known as ASA404 or DMXAA, extended survival time, says Mark McKeage, PhD, an associate professor in clinical pharmacology at the University of Auckland, New Zealand, who is presenting the findings at the American Association for Cancer Research — International Association for the Study of Lung Cancer meeting in Coronado, Calif.
In 1796, English physician Edward Jenner decided to investigate a tale he had often heard — that milkmaids infected with cowpox became immune to smallpox, a much more dangerous affliction. To test this theory, Jenner inoculated an eight-year-old boy with pus from the blisters of a milkmaid who had caught cowpox. Two months later, Jenner injected the boy with material from a smallpox lesion. The boy did not become ill, nor did the 22 people on whom Jenner later performed the same procedure.
Jenner had just made one of the most significant discoveries in medical history — a vaccine against smallpox, one of the greatest scourges humans have faced. But, his methodology would not make it past the ethical review boards that now govern research on human subjects.
Today, scientists testing experimental vaccines usually rely on laboratory experiments, measuring the immune responses of cells grown in Petri dishes, or animal studies, which dont always offer an accurate picture of the human immune response. Once vaccines become promising enough to test in humans, researchers can vaccinate volunteer subjects but cant purposely expose them to the pathogen. For example, in a recent study of an AIDS vaccine, researchers administered either the vaccine or a placebo to more than 16,000 volunteers in Thailand, then followed them for three years to see how many became infected.
That kind of study is useful but doesnt allow researchers to fully control the experimental conditions. Now, researchers at MIT and elsewhere are trying a new tactic — recreating the human immune system in a mouse. With mice that have human immune cells, you can “study immune response to pathogens that you cant give to people,” says Jianzhu Chen, the MIT biology professor leading this effort
Pear trumps apple when it comes to body shape and your health.A new review suggests that having body fat stored in your thighs and backside may actually be good for you. Especially compared with the risks of storing excess fat around the mid-section.Researchers reviewed recent studies on the health effects of body fat distribution and found that having body fat in the thighs and backside, known as gluteofemoral fat, helps protect against heart disease and diabetes.It’s not the first time experts have said that body fat distribution may play a significant role in health and disease risk. Previous studies have already shown that belly or abdominal fat raises the risk of heart disease by increasing blood pressure and cholesterol levels and is also an independent risk factor for type 2 diabetes.
In the early stages of Alzheimer’s disease, patients typically suffer a major loss of the brain connections necessary for memory and information processing. Now, a combination of nutrients that was developed at MIT has shown the potential to improve memory in Alzheimer’s patients by stimulating growth of new brain connections.
In a clinical trial of 225 Alzheimer’s patients, researchers found that a cocktail of three naturally occurring nutrients believed to promote growth of those connections, known as synapses, plus other ingredients (B vitamins, phosopholipids and antioxidants), improved verbal memory in patients with mild Alzheimer’s.
Many experiments in biology rely on manipulating cells: adding a gene, protein, or other molecule, for instance, to study its effects on the cell. But getting a molecule into a cell is much like breaking into a fortress; it often relies on biological tricks such as infecting a cell with a virus or attaching a protein to another one that will sneak it through the cell’s membrane. Many of these methods are specific to certain types of cells and only work with specific molecules. A paper in this week’s Proceedings of the National Academy of Sciences offers a surprisingly simple and direct alternative: using nanowires as needles to poke molecules into cells.
The so-called “longevity gene” may do more than add years to your life. It may also help stave off age-related cognitive decline, and this discovery is paving the way for new drugs to treat Alzheimer’s disease, a study shows.
The longevity gene is a variant of the cholesteryl ester transfer protein (CETP) gene, which was discovered in 2003. This variant has been shown to improve cholesterol levels by increasing HDL “good” cholesterol and regulating the size of cholesterol particles. As a result, it has been linked to longevity and lower heart disease risk, but how or if this variant affects the cognitive decline that is known to occur with aging was not known — until now.
Eating pomegranates or drinking pomegranate juice may help prevent and slow the growth of some types of breast cancer.
A new study shows a group of phytochemicals called ellagitannins found in abundance in pomegranates inhibited the growth of estrogen-responsive breast cancer in laboratory tests.