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April 11, 2007, 10:27 PM CT
Key Player In Embryonic Muscle Development
Muscle fibers are large cells that contain a number of nuclei. They begin, like all animal cells, as naive embryonic cells. These cells differentiate, producing intermediate cells called myoblasts that are now destined to become muscle. New myoblasts then seek out other myoblasts, and when they find each other, they stick together like best friends. In the final stage of muscle fiber development, the cell membranes of attached myoblasts open up and fuse together, forming one large, unified cell.
How myoblasts identify other myoblasts and how they cling together had been established, but the way that the cell membranes fuse into one has remained a mystery. Now, a study by Weizmann Institute researchers has shed light on this mystery. The study was carried out by research student Rada Massarwa and lab technician Shari Carmon under the guidance of Dr. Eyal Schejter and Prof. Ben-Zion Shilo of the Institute's Molecular Genetics Department, with help from Dr. Vera Shinder of the Electron Microscopy Unit. The cells' system for identifying other myoblasts and sticking to them consists of protein molecules that poke through the outer cell membrane one end pointing out and the other extending into the body of the cell. These recognition proteins anchor the cells together, but what makes myoblasts open their doors to each other and merge into one cell?........
Posted by: Scott Read more Source
April 11, 2007, 10:21 PM CT
Liver regeneration may be simpler
The way the liver renews itself may be simpler than what researchers had been assuming. A new study, appearing in the April 13 issue of The Journal of Biological Chemistry, provides new information on the inner workings of cells from regenerating livers that could significantly affect the way physicians make livers regrow in patients with liver diseases such as cirrhosis, hepatitis, or cancer.
"The human liver is one of the few organs in the body that can regenerate from as little as 25 percent of its tissue," says Seth Karp, assistant professor of surgery at Harvard Medical School, Boston, and main author of the study. "It is not known how the liver does it, but our results provide some details of what makes the liver so unique."
Eventhough organ regeneration has been observed in a number of animals, the details of how it happens at the cellular level are not yet completely understood. So far, researchers have shown that cells that participate in tissue regeneration behave as if they were part of a growing organ in an embryo. In other words, the cells act as if the liver is growing, as do other organs in a developing embryo.
A number of of the proteins that induce organ regeneration have been identified and researchers are now trying to make organs regrow by stimulating these proteins. Regrowing livers this way would be particularly useful for patients whose livers are so damaged say, by a tumor that has spread to most of the liver that a large part would be removed. Unless such patients receive the right amount of liver transplant from an organ donor, they do not always survive. Quickly stimulating the growth of the remaining portion of their liver could be their only chance of survival.........
Posted by: Sue Read more Source
April 10, 2007, 8:42 PM CT
Nanoparticles improve delivery of medicines
Tiny, biodegradable particles filled with medicine may also contain answers to some of the biggest human health problems, including cancer and tuberculosis. The secret is the size of the package.
Using an innovative technique they invented, a Princeton University-led research team has created particles that can deliver medicine deep into the lungs or infiltrate cancer cells while leaving normal ones alone. Only 100 to 300 nanometers wide -- more than 100 times thinner than a human hair -- the particles can be loaded with medicines or imaging agents, like gold and magnetite, that will enhance the detection capabilities of Computerized axial tomography scans and MRIs.
"The intersection of materials science and chemistry is allowing advances that were never before possible," said Robert Prud'homme, a Princeton chemical engineering professor and the director of a National Science Foundation-funded team of scientists at Princeton, the University of Minnesota and Iowa State University. "No one had a good route to incorporate drugs and imaging agents in nanoparticles".
Prud'homme will discuss the work April 11 in a talk titled "How Size Matters in the Retention of Nanomaterials in Tissue," to be given at the National Academy of Sciences meeting on Nanomaterials in Biology and Medicine in Washington, D.C.........
Posted by: Scott Read more Source
April 10, 2007, 6:34 PM CT
Misusing vitamin to foil drug test
Taking excessive doses of a common vitamin in an attempt to defeat drug screening tests may send the user to the hospitalor worse.
Scientists from The Children's Hospital of Philadelphia and The University of Pennsylvania reported on two adults and two adolescents who suffered toxic side effects from taking large amounts of niacin, also known as vitamin B3, in mistaken attempts to foil urine drug tests.
Both adult patients suffered skin irritation, while both adolescents had potentially life-threatening reactions, including liver toxicity and hypoglycemia (low blood sugar), as well as nausea, vomiting and dizziness. One of the teens also had disrupted heart rhythms.
All four patients recovered after therapy in hospital emergency rooms for the adverse effects. The report appeared online in the Annals of Emergency Medicine.
"Testing urine for drugs is becoming increasingly common for job applicants," said study leader Manoj K. Mittal, M.D., a fellow in Emergency Medicine at The Children's Hospital of Philadelphia. "Because niacin is known to affect metabolic processes, there is a completely unfounded claim that it can rapidly clear the body of drugs such as cannabis and cocaine. However, niacin is toxic when taken in large amounts".
Niacin is easily available as an over-the-counter vitamin supplement. As a vitamin, the daily recommended intake is 15 milligrams, but niacin is used in much larger doses to treat vitamin deficiencies and other conditions. "People often assume niacin is completely safe," said Dr. Mittal. "As a water-soluble vitamin, it is easily excreted from the body. However, the body has its limits, and some of these patients took 300 times the daily recommended dose of niacin." Dr. Mittal added that there is a report in the medical literature of a patient who suffered liver failure, requiring a liver transplant, after taking excessive doses of niacin.........
Posted by: Janet Read more Source
April 10, 2007, 6:33 PM CT
Heavy Cost of Type 2 Diabetes Complications
A first-of-its-kind report looking at the prevalence and cost of type 2 diabetes complications shows that an estimated three out of five people (57.9 percent) with type 2 diabetes have at least one of the other serious health problems commonly associated with the disease, and that these health problems are taking a heavy financial toll on the United States. In 2006, the nation spent an estimated $22.9 billion on direct medical costs related to diabetes complications.*.
The new report, titled State of Diabetes Complications in America, also shows that estimated annual healthcare costs for a person with type 2 diabetes complications are about three times higher than that of the average American without diagnosed diabetes. These complications, which can include heart disease, stroke, eye damage, chronic kidney disease and foot problems that can lead to amputations, cost a person with type 2 diabetes almost $10,000 each year.* People with diabetes complications pay nearly $1,600 out of their own pockets for costs that are not reimbursed by insurance, such as co-payments and deductibles.* This amount is significant, considering that according to the National Health Interview Survey, an estimated 40 percent of adults with diabetes reported a family income of less than $35,000 per year in 2005.........
By Kottapurath Kunjumoideen MD Read more Source
April 10, 2007, 6:06 PM CT
Protein Required For Two Neighboring Cells To Fuse
Working with fruit flies, researchers at Johns Hopkins have discovered a protein mandatory for two neighboring cells to fuse and become one "super cell."
Most cells enjoy their singular existence, but the strength and flexibility of muscles relies on hundreds or even thousands of super cells that make large-scale motion smooth and coordinated, such as flexion of a bicep.
The newly discovered protein, dubbed Solitary, coordinates the movement of tiny molecular delivery trucks to a cell's surface. Cells that lack Solitary stay, well, solitary. "They refuse to fuse," says Hopkins assistant professor of molecular biology and genetics Elizabeth Chen, Ph.D., whose report on the work is online this week in Developmental Cell.
Chen and her team studied fruit fly embryo muscles to find the molecular signals that tell two neighboring cells to join as one, plucking out for further study those embryos containing cells that refused to fuse.
They then compared the genetic sequences from healthy embryos with sequences from defective embryos to locate differences and identify the genes responsible for unfused muscle cells. In the process, they identified Solitary.
Chen's team next made a tool to see the Solitary protein, enabling them to track its localization under a fluorescent microscope. At each future fusion point between cells that they examined in the fly muscles, they saw concentrations of glowing clumps of Solitary protein.........
Posted by: Scott Read more Source
April 10, 2007, 6:00 PM CT
Eye diseases for great painters
After writing two books on the topic of artists and eye disease, the Stanford University School of Medicine ophthalmologist decided to go one step further and create images that would show how artists with eye disease actually saw their world and their canvases. Combining computer simulation with his own medical knowledge, Marmor has recreated images of some of the masterpieces of the French impressionistic painters Claude Monet and Edgar Degas who continued to work while they struggled with cataracts and retinal disease.The results are striking:
In Marmor's simulated versions of how the painters would most likely have seen their work, Degas' later paintings of nude bathers become so blurry it's difficult to see any of the artist's brush strokes. Monet's later paintings of the lily pond and the Japanese bridge at Giverny, when adjusted to reflect the typical symptoms of cataracts, appear dark and muddied. The artist's signature vibrant colors are muted, replaced by browns and yellows.
"These simulations may lead one to question whether the artists intended these late works to look exactly as they do," said Marmor who has long had interest in both the mechanics of vision and the vision of artists. "The fact is that these artists weren't painting in this manner totally for artistic reasons".........
Posted by: Mike Read more Source
April 9, 2007, 11:03 PM CT
Chance of hysterectomy predicted
A woman's chance of undergoing a hysterectomy can now be accurately predicted, as per new UCSF study findings.
Results from a four-year study of 762 women with various symptoms of uterine distress, such as chronic pelvic pain, abnormal bleeding or fibroids, are published in the April 2007 issue of the "Journal of the American College of Surgeons." Study findings also are available online at www.journalacs.org
The findings confirm a widely held, but untested, belief in gynecology that the more symptoms of discomfort a woman has, as well as the longer she has tried alternative therapies unsuccessfully, the more likely she is to have a hysterectomy, said lead investigator Lee Learman, MD, a professor in the UCSF Department of Obstetrics, Gynecology and Reproductive Sciences.
"In the past, we were never entirely sure which symptoms were most likely to lead to a hysterectomy and which were most likely to be controlled with conservative therapys, so women received differing advice from individual doctors across the country," he added. "Now, for the first time, we have easily-measured, clinical characteristics that we can assess and use to accurately counsel patients on their options".
That, in turn, means women with a high likelihood of hysterectomy can avoid years of pain and discomfort while trying other options first and women with a low likelihood of hysterectomy can explore other options with more confidence of their success, Learman said.........
Posted by: Emily Read more Source
April 3, 2007, 10:49 PM CT
How Lead Exposure Produces Learning Deficits
Tomas R. Guilarte, PhD
A study of young adult rats by scientists from the Johns Hopkins Bloomberg School of Public Health provides evidence that explains exactly how exposure to lead during brain development produces learning deficits. The study shows that exposure to levels of lead that are similar to those measured in lead-intoxicated children reduces the birth and survival of new neurons (neurogenesis) in the brain. Lead also alters the normal development of newly born neurons in a part of the brain (hippocampus) known to be important for learning and memory. The study is reported in the March 30, 2007, issue of Neuroscience.
"There was a dogma in neuroscience that you were born with all the neurons you would ever have, but that thinking has changed dramatically in the last 20 years," said Tomás R. Guilarte, PhD, senior author of the study and professor of environmental health sciences at the Johns Hopkins Bloomberg School of Public Health. "The exciting idea is that researchers have discovered ways to increase the number of new neurons, and this may facilitate learning in the hippocampus portion of the brain".
The scientists studied young adult rats, using a group of lead-treated and non-treated (control) rats. When they examined the brains of lead-exposed rats, they observed that fewer neurons were born and those neurons that were born survived for a shorter amount of time and had abnormal development.........
Posted by: JoAnn Read more Source
April 3, 2007, 10:46 PM CT
Rabies-based Vaccine Against Hiv
Rabies, a relentless, ancient scourge, may hold a key to defeating another implacable foe: HIV. Researchers at Jefferson Medical College in Philadelphia have used a drastically weakened rabies virus to ferry HIV-related proteins into animals, in essence, vaccinating them against an AIDS-like disease. The early evidence shows that the vaccine which doesnt protect against infection prevents development of disease.
Reporting April 1, 2007 in the Journal of Infectious Diseases, the researchers showed that two years after the initial vaccination, four vaccinated non-human primates were protected from disease, even after being "challenged" with a dangerous animal-human virus. Two control animals developed an AIDS-like disease.
Matthias Schnell, Ph.D., professor of microbiology and immunology at Jefferson Medical College of Thomas Jefferson University, and his co-workers tested the effects of inserting two different viral proteins into the rabies virus genome, and using such viruses-based vaccines in preventing disease in rhesus macaques. One was a glycoprotein on the surface of HIV, while the other was an internal protein from simian immunodeficiency virus (SIV). They used the latter because HIV does not cause disease in monkeys.
The idea was that such rabies vehicles, or "vectors," would help attract a strong response from the animals immune system, though the rabies virus used cannot cause disease. Such vectors are based on a type of rabies vaccine strain that has been used for more than 20 years in oral vaccines against rabies in wildlife in Europe. The study was aimed at studying the safety and effectiveness of the rabies vaccine approach against HIV and related diseases.........
Posted by: Mark Read more Source
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Did you know?
Studies in monkeys and women suggest that unlike traditional estrogen therapy, a diet high in the natural plant estrogens found in soy does not increase the risk of uterine cancer in postmenopausal women, according to Mark Cline, D.V.M., Ph.D., an associate professor of comparative medicine at Wake Forest University Baptist Medical Center.
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