Archive for August 2011
RNA molecules have long been known for their role in translating genes to proteins inside a cell, but more recently, scientists have found large numbers of RNA molecules that don’t code for proteins but seem to have other cellular roles. Most research in mammals has focused on tiny RNA molecules called microRNAs, but a new study, published this week in Nature, describes the far-reaching effects of much larger and relatively unstudied RNA molecules called lincRNAs (short for large intergenic noncoding RNAs). The study identifies lincRNAs that play a role in the function of embryonic stem cells, and suggests trying to use lincRNAs to manipulate these cells to spawn other cell types.
An experimental pill to prevent blood clots exceeded already high expectations as a better therapy for millions of people with atrial fibrillation, according to final results of a worldwide study released Sunday.
The study was featured at the European Society of Cardiology in Paris and simultaneously published on the Web site of The New England Journal of Medicine.
“It’s a remarkable achievement,” said Dr. Valentin Fuster, a past president of American and world heart associations, who was not involved with the trial. “This is one of the most significant advances in cardiovascular medicine in the last five years, no question,” Dr. Fuster, chairman of federal and medical panels on atrial fibrillation and director of the heart center at Mount Sinai Medical Center in New York, said in an interview.
The twice-daily pill, to be called Eliquis, prevented 21 percent more strokes than the blood thinner warfarin, a standard treatment for heart arrhythmia, and resulted in 31 percent fewer incidents of major bleeding over an average of 1.8 years in the study.
A diet that incorporates cholesterol-lowering foods like soy, nuts, and plant sterols may work better at lowering cholesterol levels than a traditional low-fat diet.
A new study shows that people with high cholesterol who followed the portfolio diet, which includes a combination of cholesterol-lowering foods, lowered their low-density lipoprotein (LDL) cholesterol levels by about 13% after six months on the diet. That’s compared with a 3% LDL reduction among those who followed a traditional diet low in saturated fat.
“Given that cardiovascular disease is our major killer, we feel that a lot of people will benefit to a greater or lesser extent by adopting this diet, which is basically a plant-based approach,” says researcher David Jenkins, MD, Canada Research Chair at the University of Toronto. “Those who may want to follow the diet more specifically are those who are on the cusp for statin treatment.”
Researchers in Canada have shown that a special cholesterol-lowering diet works well – even with only two nutritional counseling sessions over six months.
Making dietary changes like eating oat bran for breakfast, drinking soy milk instead of dairy, soy burgers in place of hamburgers, and fruit and nuts instead of a full lunch prompted a double-digit drop in both total cholesterol and LDL or “bad” cholesterol.
The study was published Tuesday in the Journal of the American Medical Association.
Lead author Dr. David Jenkins, Canada research chair in nutrition and metabolism at the University of Toronto and St. Michael’s Hospital, had previously shown the effectiveness of a cholesterol-lowering diet when all the meals were provided to participants.
Nine years after getting gene therapy for a rare, inherited immune system disorder often called “bubble boy disease,” 14 out of 16 children are doing well, researchers report.
The children were born with severe combined immunodeficiency disease (SCID). They got an experimental gene therapy in the U.K.
A new report shows that nine years later, 14 of the 16 children had working immune systems and were leading normal lives.
“These children, who would have died very young without treatment, are participating in life as fully as their brothers and sisters,” researcher H. Bobby Gaspar, MD, PhD, tells WebMD. “Most of them are going to school, playing ball, and going to parties.”
A new atlas of gene expression in the mouse brain provides insight into how genes work in the outer part of the brain called the cerebral cortex. In humans, the cerebral cortex is the largest part of the brain, and the region responsible for memory, sensory perception and language.
Mice and people share 90 percent of their genes so the atlas, which is based on the study of normal mice, lays a foundation for future studies of mouse models for human diseases and, eventually, the development of treatments. Researchers from the National Human Genome Research Institute (NHGRI), part of the National Institutes of Health, and from Oxford University in the United Kingdom, published a description of the new atlas in the Aug. 25, 2011, journal Neuron. The study describes the activity of more than 11,000 genes in the six layers of brain cells that make up the cerebral cortex.
“This study shows the power of genomic technologies for making unexpected discoveries about the basic biology of life,” said NHGRI Director Eric D. Green, M.D., Ph.D. “The brain is our most complex organ. Until we understand how it is built and how it functions based on our genetic blueprint, we will be hampered in keeping the brain healthy or dealing with its terrible diseases.”
To map gene activity in all six layers of the mouse cerebral cortex, the research team first micro-dissected the brains of eight adult mice, separating the layers of the cortex. They then purified processed RNAs, including messenger RNA, from each cortical layer.
The cell creates messenger RNA (mRNA) when genes are switched on and the DNA code is read out to make proteins. The presence of an mRNA indicates that a gene is turned on, and the amount of mRNA shows the extent to which the gene is active.
To determine which genes were turned on and to what extent, the researchers used a relatively new sequencing technology called RNA-seq. The technique depends on two steps. The researchers first copy processed RNA into a form of DNA, and then sequence the resulting DNA on a second-generation, DNA sequencing instrument. The resulting massive data set must then be analyzed by a cluster of computers to determine which genes have been turned on in the brain cells and to what extent.
The international collaborators have made the new atlas freely available at http://genserv.anat.ox.ac.uk/layers.
By determining the gene activity in each layer, researchers believe it will be possible to connect brain anatomy, genetics and disease processes with greater precision. The research team found that more than half of the genes expressed in the mouse cerebral cortex showed different levels of activity in different layers. These differences point to the areas where specific genes play important roles.
“We found that genes associated with some human diseases were more active in certain layers. For example, we detected genes previously associated with Parkinson’s disease in layer five and Alzheimer’s disease in layers two and three. These are correlations, not necessarily causal, but they do suggest directions for future research,” said T. Grant Belgard, lead author of the paper and an NIH-Oxford fellow in NHGRI’s Genome Technology Branch. “Knowing the detailed pattern of expression of all genes in the cortex and how this fits into the overall brain architecture will help us understand how genes act together to sustain the cells and circuits that underlie behavior and disease.”
Using the technique, researchers detected a vast array of noncoding RNAs. These are RNAs produced from DNA that do not encode proteins, but probably play a critical role in regulating genes and controlling biological processes. Some of these were active in specific layers, and many had not previously been discovered.
The study also further demonstrated the importance of alternative splicing in gene function within the brain. Messenger RNA includes segments called exons that can be stitched together in different ways to produce a mature message that the cell uses to produce proteins. The alternative splicing process allows a single gene to produce many different proteins that can have different functions in different cells or at different times in a cell’s life.
Many alternatively spliced genes showed different distributions of the alternative forms between layers. This includes the Mtap4 gene, whose activity is altered in Alzheimer’s disease.
Next year, Belgard and others will be involved in an effort to replicate the mouse brain atlas for parts of the human brain.
A relatively simple combination of naturally occurring sugars and amino acids offers a plausible route to the building blocks of life, according to a paper published in Nature Chemistry co-authored by a professor at the University of California, Merced.
The study, “A Route to Enantiopure RNA Precursors from Nearly Racemic Starting Materials,” shows how the precursors to RNA could have formed on Earth before any life existed. It was authored by Jason E. Hein, Eric Tse and Donna G. Blackmond, a team of researchers with the Scripps Research Institute. Hein is now a chemistry professor with UC Merced. The paper was published online Sunday.
Biological molecules, such as RNA and proteins, can exist in either a natural or unnatural form, called enantiomers. By studying the chemical reactions carefully, the research team found that it was possible to generate only the natural form of the necessary RNA precursors by including simple amino acids.
“These amino acids changed how the reactions work and allowed only the naturally occurring RNA precursors to be generated in a stable form,” said Hein. “In the end, we showed that an amazingly simple result emerged from some very complex and interconnected chemistry.”
The natural enantiomer of the RNA precursor molecules formed a crystal structure visible to the naked eye. The crystals are stable and avoid normal chemical breakdown. They can exist until the conditions are right for them to change into RNA.
Tiny particles made of polymers hold great promise for targeted delivery of drugs and as structural scaffolds for building artificial tissues. However, current production methods for such microparticles yield a limited array of shapes and can only be made with certain materials, restricting their usefulness.
In an advance that could broadly expand the possible applications for such particles, MIT engineers have developed a way to make microparticles of nearly any shape, using a micromold that changes shape in response to temperature. They can also precisely place drugs into different compartments of the particles, making it easier to control the timing of drug release, or arrange different cells into layers to create tissue that closely mimics the structure of natural tissues.
The new technique, described in a paper published online July 18 in the Journal of the American Chemical Society, also allows researchers to create microparticles from a much more diverse range of materials, says Halil Tekin, an MIT graduate student in electrical engineering and computer science and lead author of the paper.
Working closely with a team of researchers from Duke University, scientists from the Florida campus of The Scripps Research Institute have helped identify a molecular pathway that plays a key role in stress-related damage to the genome, the entirety of an organism’s hereditary information.
The new findings, published in the journal Nature on August 21, 2011, could not only explain the development of certain human disorders, they could also offer a potential model for prevention and therapy. Read the rest of this entry »
Aneuploidy—when the cells of an organism contain more or fewer than the standard number of chromosomes for its species—is found in greater than 90 percent of all human cancers. But how exactly it relates to cancer, and whether it is a cause or merely a consequence of genomic instability, has long been a mystery. Two new studies published today (August 18) in Science show that it’s probably both, pointing to a gene defect that can cause aneuploidy, and elucidating the disastrous effects of aneuploidy on a cell’s genome.
“Aneuploidy is found in virtually all cancers, yet very little is known about its origins or its effects,” said a cancer biologist Bert Vogelstein at Johns Hopkins Medicine, who was not involved in the research. “These two papers provide some really excellent clues to what’s going on.”
A new microscope has allowed researchers to watch molecules move within a cell on a millisecond-by-millisecond time scale for the first time. The novel method, which combines two preëxisting microscopic techniques, opens a window onto cellular processes that had previously been undetectable, unveiling molecular activity within a cell at a much finer level than ever before possible.
“This allows us to look at interactions of molecules, and their mobility,” says Malte Wachsmuth, a cell biophysicist at the European Molecular Biology Laboratory in Heidelberg, Germany, who helped develop the new microscope. Current microscopy techniques can home in on a single spot within a cell, but they can miss vital information when the focus moves from one spot to another. “A typical protein might spend one to two milliseconds in such a spot,” Wachsmuth says. “Molecules are quite mobile, diffusing all around, and it’s a very fast process. A lot can happen in a few tens of milliseconds.”
Obese people who are otherwise healthy live as long as normal-weight people, new research from Canada suggests.
Some obese but healthy people actually are less likely to die of heart problems than normal-weight people who have some medical conditions, the researchers found.
“You shouldn’t just look at body weight alone,” says researcher Jennifer Kuk, PhD, assistant professor of kinesiology and health science at York University in Toronto.
“A healthy lifestyle, including being physically active and eating a healthy diet, is probably more important than your body weight and focusing on weight loss, if you are otherwise healthy,” she tells WebMD.
Kuk and her colleagues used a new tool that helps identify which people would benefit from weight loss and from weight loss surgery. Called the Edmonton Obesity Staging System (EOSS), it grades or stages obese people depending on whether they have diseases such as heart disease or cancer.
The study was led by Lori Daiello, PharmD, a research scientist at the Rhode Island Hospital Alzheimer’s Disease and Memory Disorders Center. Data for the analyses was obtained from the Alzheimer’s Disease Neuroimaging Initiative (ADNI), a large multi-center, NIH-funded study that followed older adults with normal cognition, mild cognitive impairment, and Alzheimer’s Disease for over three years with periodic memory testing and brain MRIs.
The study included 819 individuals, 117 of whom reported regular use of fish oil supplements before entry and during study follow-up. The researchers compared cognitive functioning and brain atrophy for patients who reported routinely using these supplements to those who were not using fish oil supplements.
Daiello reports that compared to non-users, use of fish oil supplements was associated with better cognitive functioning during the study. However, this association was significant only in those individuals who had a normal baseline cognitive function and in individuals who tested negative for a genetic risk factor for Alzheimer’s Disease known as APOE4. This is consistent with previous research.
Read the rest of this entry »
Continuity of sleep, not just the total hours of nightly slumber, is crucial to forming and retaining memories, a new study in mice suggests.
Mice couldn’t remember objects they’d seen before after a night of interrupted sleep, Asya Rolls of Stanford and her colleagues report online July 25 in the Proceedings of the National Academy of Sciences. Even though the mice got just as much sleep as normal and slept as intensely as usual, breaking that sleep into one-minute chunks was enough to erase the memory of toys the animal had seen before.
The results emphasize that sleep is a process, says Paul Shaw, a neuroscientist at Washington University in St. Louis who was not involved in the study. “Whatever biological function sleep serves takes time,” he says. “So if you wake up, you disrupt that process and have to start from scratch again.”
For the last decade cancer research has been guided by a common vision of how a single cell, outcompeting its neighbors, evolves into a malignant tumor.
Through a series of random mutations, genes that encourage cellular division are pushed into overdrive, while genes that normally send growth-restraining signals are taken offline.
With the accelerator floored and the brake lines cut, the cell and its progeny are free to rapidly multiply. More mutations accumulate, allowing the cancer cells to elude other safeguards and to invade neighboring tissue and metastasize.
These basic principles — laid out 11 years ago in a landmark paper, “The Hallmarks of Cancer,” by Douglas Hanahan and Robert A. Weinberg, and revisited in a follow-up article this year — still serve as the reigning paradigm, a kind of Big Bang theory for the field.
But recent discoveries have been complicating the picture with tangles of new detail. Cancer appears to be even more willful and calculating than previously imagined.
Scientists have pinpointed a rare gene variant that increases a woman’s risk of developing ovarian cancer six-fold. The discovery will lead to new diagnostic tests to identify the cancer earlier and provides better information to help doctors choose targeted anti-cancer drugs.
Ovarian cancer can develop without many clear symptoms and is the fifth most common cancer in women. In the UK, 6,500 cases are diagnosed every year and, of those, almost 4,000 end in death.
In the latest study, scientists found that, in around 60 cases of ovarian cancer every year in the UK, the women had faults in a gene called RAD51D. Anyone who inherits a faulty version of this gene, they calculated, therefore had a one in 11 chance of developing ovarian cancer, compared with one in 70 for the general population.
Sleep apnea, a fairly common, treatable disorder that causes people to stop breathing momentarily while they sleep, may lead to cognitive impairment and even dementia, according to a new study of elderly women.
Women in the study with sleep apnea or other sleep disorders that affected their breathing were much more likely than those with normal sleep habits to develop cognition problems within five years, said researchers at UCSF and California Pacific Medical Center, who published the results in the Journal of the American Medical Association today.
German and Spanish mice have rapidly evolved the trait by breeding with an Algerian species from which they have been separate for over a million years.
The researchers say this type of gene transfer is highly unusual and normally found in plants and bacteria.
The Current Biology report says this process could yield mice resistant to almost any form of pest control.
Warfarin is a drug widely used in medicine as an anti-coagulant to prevent the build-up of harmful blood clots. It works through inhibiting a protein called VKORC1. This protein turns on our ability to produce vitamin K, which is essential for clotting.
The newly approved drug Xarelto appears to prevent strokes at least as well as the standard treatment warfarin in people who have a heart condition that puts them at high risk for blood clots, a study shows.
Xarelto was approved by the FDA in July to prevent dangerous blood clots in people having hip and knee replacement surgery.
Next month, a panel of experts will consider whether the agency should also approve its use as a once-daily treatment for atrial fibrillation.
Atrial fibrillation causes the heart to pump in an irregular, uncoordinated way that may allow blood to pool and clot in its upper chambers. Those clots can travel to the brain, causing a stroke.
Patients with atrial fibrillation are commonly prescribed the blood-thinning drug warfarin, which is also sold under the brand names Coumadin and Jantoven.
Red meat, particularly processed red meats like bacon, sausage, and hot dogs, may increase a person’s risk of developing type 2 diabetes. The more processed or unprocessed red meat a person eats, the greater the risk, according to a new study in the American Journal of Clinical Nutrition.
Type 2 diabetes is linked with obesity. It occurs when they body does not produce enough of the hormone insulin, or the cells do not use insulin properly. Insulin helps the body use glucose or blood sugar for energy. When blood sugar remains elevated with diabetes, complications such as heart disease, blindness, and nerve and kidney damage can occur.
In the study, participants who ate one 3.5-ounce serving of non-processed red meat a day, such as steak or hamburger, were almost 20% more likely to develop type 2 diabetes.
Those who ate half of this amount of processed meat, such as two slices of bacon or one hot dog, had a 51% increased risk for developing diabetes.
“The amount is not huge, but the risk is pretty high,” says Frank B. Hu, MD, PhD, a professor of nutrition and epidemiology at Harvard School of Public Health in Boston. “Regular consumption of red meat, especially processed, is associated with an increased risk for type 2 diabetes. The findings are important given the rising epidemic of diabetes and the increasing consumption of red meat.”
But an industry group disputes the findings of the study.
A biochemical pathway long associated with diarrhea and intestinal function may provide a new therapeutic target for treating ADHD (Attention Deficit Hyperactivity Disorder) other neuropsychiatric disorders, according to a team of scientists from China and the United States reporting Aug. 11 in Science.
Scientists have for the last quarter century studied the intestinal membrane receptor protein, guanylyl cyclase-C (GC-C) for its role in diarrheal disease and other intestinal functions, according to Mitchell Cohen, M.D., U.S. author on the study and director of Gastroenterology, Hepatology and Nutrition at Cincinnati Children’s Hospital Medical Center. In fact, it had been thought that GC-C was found primarily in the intestine.
In the current study, scientists in China who collaborated with Dr. Cohen discovered that the receptor is also expressed in critical areas of the brain. Read the rest of this entry »
New measurement technologies and techniques provide researchers more complete look at neurological activity
In 1991, Carl Lewis was both the fastest man on earth and a profound long jumper, perhaps the greatest track-and-field star of all time in the prime of his career. On June 14th of that year, however, Carl Lewis was human. Leroy Burrell blazed through the 100-meters, besting him by a razor-thin margin of three-hundredths of a second. In the time it takes the shutter to capture a single frame of video, Lewis’s three-year-old world record was gone.
In a paper just published in the journal Neuron, a team at the Stanford School of Engineering, led by electrical engineers Krishna Shenoy and Maneesh Sahani, explored the neurological explanations for why Lewis may have lost that day. The team, which included graduate students Afsheen Afshar, Gopal Santhanam, Byron Yu, and post-doctoral researcher Stephen Ryu, studied how the brain plans for and executes movements in reaction to a “go” signal.
The advent of new measurement technologies that permit researchers to monitor up to hundreds of individual neurons simultaneously, combined with new analytical mathematics, are providing a revealing look inside the brain and a better understanding of the neurological processes behind the planning and execution of motion.
“This research holds great promise in many areas of neuroscience, in particular human prostheses that can be controlled by the brain,” said Shenoy. Read the rest of this entry »
Posted August 10, 2011on:
The discovery of a fundamental, previously unknown property of microbial nanowires in the bacterium Geobacter sulfurreducens that allows electron transport across long distances could revolutionize nanotechnology and bioelectronics, says a team of physicists and microbiologists at the University of Massachusetts Amherst.
Their findings reported in the Aug. 7 advance online issue of Nature Nanotechnology may one day lead to cheaper, nontoxic nanomaterials for biosensors and solid state electronics that interface with biological systems.
Read the rest of this entry »
Discovery has implications for autoimmune diseases, HIV infection and possibly in cancer as a biomarker and in the development of new treatments
New research led by Derya Unutmaz, MD associate professor, the Departments of Pathology, Medicine, and Microbiology at NYU School of Medicine and Mark Sundrud, PhD, of Tempero Pharmaceuticals, Inc., has identified a novel sensory pathway that modulates the potency of Th17 cell responses. The new research is highlighted in the August 8th online edition of the Journal of Experimental Medicine. The study has found that when memory Th17 cells are exposed to a class of secreted proteins called gamma-c cytokines (IL-2, IL-15 or IL-7), they become armed to release their potent immune mediators, which are also a family of cytokines (such as IL-17 and IL-22).
The immune system has evolved to respond to external threats such as viral and bacterial infections. However, the immune response is also tightly regulated to prevent excessive tissue damage or autoimmune diseases, resulting from a reaction produced by white blood cells or antibodies acting on the body. A subset of T lymphocytes called Th17 cells has powerful functions to sustain and mediate protective immune responses against some bacterial and fungal infections. Th17 cells are also implicated in excessive inflammatory autoimmune diseases such as psoriasis and multiple sclerosis. How Th17 cells regulate their potent immune functions has not been fully understood. Read the rest of this entry »
Squishy, doughnut-shaped disks can make the difference between a pain-free, active lifestyle or years of back discomfort. When the disks that normally cushion each vertebra in the spine start to degenerate, due to aging or injury, nerves can be pinched and movement impeded. But degenerating disks may soon be replaceable with bioengineered disk implants grown in the laboratory. A research team has implanted living, biologically based disks into rats’ spines and found that they allow for as much movement as native, healthy disks.
“This is, in my opinion, in a whole different league than tissues that have been engineered before,” says University of Pennsylvania orthopedic bioengineer Robert Mauck, who was not involved in the study. “This is essentially opening the door for replacement of a tissue that’s central to humans walking.”
Posted August 7, 2011on:
Anyone who follows science has read enthusiastic stories about medical breakthroughs that include the standard disclaimer that the results were obtained in mice and might not carry over to humans.
Much later, there might be reports that a drug has been abandoned because clinical trials turned up unforeseen side effects or responses in humans. Given the delay, most readers probably don’t connect the initial success and the eventual failure.
But Igor Efimov, PhD, a biomedical engineer at Washington University in St. Louis who studies the biophysical and physiological mechanisms that underlie heart rhythm disorders, is acutely aware of the failure of once-promising drugs to pass clinical trials.
FINDINGS: A man-made fat called Intralipid, which is currently used as a component of intravenous nutrition and to treat rare overdoses of local anesthetics, may also offer protection for patients suffering from heart attacks.
Read the rest of this entry »
Columbia University Medical Center researchers have for the first time directly converted human skin cells into functional forebrain neurons, without the need for stem cells of any kind. The findings offer a new and potentially more direct way to produce replacement cell therapies for Alzheimer’s and other neurodegenerative diseases. Such cells may prove especially useful for testing new therapeutic leads. The study was published in the August 4 online issue of the journal Cell.
In another first, the researchers used this method — called direct reprogramming — to generate neurons from skin cells of patients with familial (early-onset) Alzheimer’s disease. The induced neurons were found to differ significantly from those made from healthy individuals, providing new insights into the development of the disease, reports study leader Asa Abeliovich, MD, PhD, associate professor of pathology & cell biology and neurology in the Taub Institute for Research on Alzheimer’s Disease and the Aging Brain at Columbia University Medical Center (CUMC). Read the rest of this entry »
French scientists have developed a novel hepatitis C vaccine that may offer the first effective way to prevent an infection that can cause chronic liver disease and cancer.
There is currently no available vaccine for hepatitis C, though some companies are developing so-called “therapeutic vaccines,” which are designed to help patients who are already infected.
The latest experimental shot has been tested successfully on mice and monkeys, but not humans, and has been shown to activate a broad response from immune system proteins called neutralizing antibodies.
The antibodies fought off multiple variants of the hepatitis C virus in tests, suggesting the new vaccine should be effective even after the virus mutates, the researchers reported on Wednesday.
Neutralizing antibodies play a central role in most existing vaccines against other diseases, but harnessing them in hepatitis C has previously proved elusive. Work to date on therapeutic vaccines has focused on another immune system mechanism known as T-cells.
Plaque buildup in the arteries is a major risk factor for strokes and heart attack, but some plaques are far more dangerous than others.
The problem is there is no good way to distinguish relatively benign plaque on artery walls from plaque that will break off and cause harm, but that may soon change.
Researchers in Italy say they have identified a genetic “signature” seen in unstable plaque from patients who had a stroke, but not in plaque that is not likely to rupture.
If the findings from the small study are confirmed, the discovery could lead to better ways to identify people with clogged arteries at risk for stroke and even new treatments to prevent and treat artery disease.
The study was reported today in the online issue of the American Heart Association journal Stroke.
Elsevier, a world-leading provider of scientific, technical and medical information products and services, introduces the Genome Viewer, a new interactive feature on SciVerse ScienceDirect for applicable life sciences journals. The Genome Viewer is a SciVerse application that displays detailed gene or genomic sequence information on the genes mentioned in an article.
The Genome Viewer utilizes a genome browser developed by NCBI (the National Center for Biotechnology Information at the National Institutes of Health). Elsevier collaborated with the NCBI as it was developing the browser, and is the first publisher to incorporate the technology into an application for viewing detailed information about the gene sequences that are mentioned in articles.
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Posted August 4, 2011on:
Female cognitive ability can limit how melodious or handsome males become over evolutionary time, biologists from The University of Texas at Austin, Louisiana State University Health Sciences Center and the Smithsonian Tropical Research Institute have observed.
Males across the animal world have evolved elaborate traits to attract females, from huge peacock tails to complex bird songs and frog calls. But what keeps them from getting more colorful feathers, longer tails, or more melodious songs? Predators, for one. Increased elaboration can draw predators in, placing an enormous cost to males with these sexy traits.
In a new paper appearing this week in Science, a group of biologists have shown that females themselves can also limit the evolution of increased elaboration.
Read the rest of this entry »
n 1758 the Swedish taxonomist Carolus Linnaeus dubbed our species Homo sapiens, Latin for “wise man.” It’s a matter of open debate whether we actually live up to that moniker. If Linnaeus had wanted to stand on more solid ground, he could have instead called us Homo megalencephalus: “man with a giant brain.
”Regardless of how wisely we may use our brains, there’s no disputing that they are extraordinarily big. The average human brain weighs in at about three pounds, or 1,350 grams. Our closest living relatives, the chimpanzees, have less than one-third as much brain—just 384 grams. And if you compare the relative size of brains to bodies, our brains are even more impressive.
Posted August 4, 2011on:
Rejoice ye vampires, the pursuit of an endless supply of blood took a major leap forward this month. Researchers at the Ontario Cancer Institute, led by John Dick, have found a way to hunt down and isolate the stem cells from which your entire blood supply is derived. Until now, these hematopoietic stem cells (HSC) have been remarkably hard to track and isolate – they represent just one in every 100,000 blood cells. Yet these HSC are remarkably potent – a single cell placed in a mouse was able to differentiate itself into every type of human blood cell – from just one cell essentially came an entire blood supply! John Dick’s team was able to identify the protein code on their surface which marks the HSC as different from other blood cells. With the knowledge of how to find HSC, scientists may be able to create huge quantities of blood stem cells for research, rocketing their work ahead. Doctors may one day be able to use similar techniques to produce vast supplies of blood for patients. After fifty years of stem cell experiments, and twenty three long years of Dr. Dick working with blood stem cells, we’ve finally isolated where they all come from. It’s an exciting time in science.
The human brain is adept at recognizing similar items and placing them into categories — for example, dog versus cat, or chair versus table. In a new study, MIT neuroscientists have identified the brain activity that appears to control this skill.
The findings, published in the July 27 issue of the journal Neuron, suggest a potential explanation for why autistic children focus intently on details, but often seem unable to group things into broad categories, says Earl Miller, the Picower Professor of Neuroscience and senior author of the paper.
“We think what may happen in autism is the system may get out of balance … and as a result, the details overwhelm the category. Then you have a brain that’s not only too good at memorizing details, it can’t help but memorize the details,” says Miller, a principal investigator at the Picower Institute for Learning and Memory at MIT.
If one is good, two can sometimes be better. Researchers at the California Institute of Technology (Caltech) have certainly found this to be the case when it comes to a small HIV-fighting protein.
The protein, called cyanovirin-N (CV-N), is produced by a type of blue-green algae and has gained attention for its ability to ward off several diseases caused by viruses, including HIV and influenza. Now Caltech researchers have found that a relatively simple engineering technique can boost the protein’s battling prowess.
“By linking two cyanovirins, we were able to make significantly more potent HIV-fighting molecules,” says Jennifer Keeffe, a staff scientist at Caltech and first author of a new paper describing the study in the Proceedings of the National Academy of Sciences (PNAS). “One of our linked molecules was 18 times more effective at preventing infection than the naturally occurring, single protein.” Read the rest of this entry »
Regenerating blood vessels is important for combating the aftereffects of a heart attack or peripheral arterial disease, and for ensuring that transplanted organs receive a sufficient supply of blood. Now researchers at Northwestern University have created a nanomaterial that could help the body to grow new blood vessels.
Samuel Stupp and his colleagues developed a liquid that, when injected into patients, forms a matrix of loosely tangled nanofibers. Each of these fibers is covered in microscopic protuberances that mimic vascular endothelial growth factor, or VEGF—a protein that occurs naturally in the body and causes chemical reactions that result in the growth of new blood vessels. By mimicking VEGF, the nanofiber has the same biological effect.
Jeff Karp, director of the Laboratory for Advanced Biomaterials and Stem-Cell-Based Therapeutics at Brigham & Women’s Hospital, says, “this is an elegant approach to rationally design engineered materials to stimulate specific biological pathways.” Karp was not involved with the project.
Capillary action: The transparent circle in the center of this image is a nanomaterial designed to mimic the protein VEGF. Here, it has enhanced the growth of blood vessels in the membrane from a chicken egg after three days.
Credit: Matthew Webbe
People who smoke, are overweight, and have other health problems in middle age may be at increased risk of developing signs of brain shrinkage and diminished planning and organization skills as they age, new research indicates.
Other health problems linked to brain shrinkage and mental decline include high blood pressure and diabetes.
“Our findings provide evidence that identifying these risk factors early in people of middle age could be useful in screening people for at-risk dementia and encouraging people to make changes to their lifestyle before it’s too late,” Charles DeCarli, MD, of the University of California-Davis in Sacramento, says in a news release.
Colon cleansing, promoted as a natural way to boost well-being, has no proven benefits and may be risky, according to a new report.
Ranit Mishori, MD, a family medicine doctor at Georgetown University School of Medicine, looked at studies that evaluated colon hydrotherapy or irrigation. She also looked at studies of cleansing by the use of laxatives, teas, and other products taken by mouth or inserted into the rectum.
“If you are a healthy human being, there is no reason to detoxify yourself using these concoctions or colon hydrotherapy,” Mishori tells WebMD.
“The body is designed to detoxify itself,” she says. “There is no need to help the body do that. If you are not a healthy person and have heart disease, diabetes, or kidney disease, definitely don’t do that.”
The study is published in The Journal of Family Practice.
A spokesman from the International Association for Colon Hydrotherapy (IACT) took issue with the report. “Colon hydrotherapy when performed by a trained therapist using FDA registered equipment and disposable speculums or rectal nozzles is safe,” says A.R. “Dick” Hoenninger, executive director of the association.
When most people hear the word amyloid, they immediately think of Alzheimer’s disease. And indeed, it was in the brains of Alzheimer’s patients that these dense protein masses were first identified. But it turns out that besides playing a role in a number of diseases, amyloids also play an important structural role in many organisms from bacteria to mammals, and might point the way to a whole new category of biologically inspired synthetic materials.
Each protein normally folds itself into a specific shape that governs many aspects of its interactions with other materials and organisms. But almost all proteins and peptides (organic molecules that are similar to proteins but shorter) can alternatively form amyloids, which all have the same essential structure but form dense, concentrated masses instead of precisely folded shapes. These densely packed cores consist of stacks of molecular structures called beta sheets, tightly bound together by hydrogen bonds; a single “seed” of amyloid can induce many of the nearby proteins to collapse into similar amyloid structures.
A close-up view of an amyloid plaque model, showing the entangled structure of amyloid fibrils that form a sticky plaque.
Image: M. Solar, MIT