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Archive - Jul 2011 - Story

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July 21st

Genes of Endangered River Turtle Reveal Ancient Influence of Maya Indians

A genetic study focusing on the Central American river turtle (Dermatemys mawii) recently turned up surprising results for a team of Smithsonian scientists involved in the conservation of this critically endangered species. Small tissue samples collected from 238 wild turtles at 15 different locations across their range in Southern Mexico, Belize, and Guatemala revealed a "surprising lack" of genetic structure, the scientists write in a paper published online on May 17, 2011, in the journal Conservation Genetics. The turtles, which are entirely aquatic, represent populations from three different river basins that are geographically isolated by significant distance and high mountain chains. "We were expecting to find a different genetic lineage in each drainage basin," explains the paper's main author Dr. Gracia González-Porter of the Center for Conservation and Evolutionary Genetics at the Smithsonian Conservation Biology Institute. "Instead, we found the mixing of lineages. It was all over the place." Despite appearing isolated, the genetic data showed the different turtle populations had been in close contact for years. "But how?" the researchers wondered. The best possible explanation, Dr. González-Porter and her colleagues say, is that for centuries humans have been bringing the turtles together. The turtles have been used as food, in trade, and in rituals for millennia, widely transported and customarily kept in holding ponds until they were needed. “For centuries, this species has been part of the diet of the Mayans and other indigenous people who lived in its historic distribution range," the scientists point out in their paper. "D.

July 16th

New Gene Mutation Discovered for Familial Parkinson’s Disease

Researchers have discovered a new gene mutation they say causes Parkinson's disease. The mutation was identified in a large Swiss family with Parkinson's disease, using advanced DNA sequencing technology. The study, published July 15, 2011, in the American Journal of Human Genetics, was led by neuroscientists at the Mayo Clinic campus in Florida and included collaborators from the U.S., Canada, Europe, United Kingdom, Asia, and the Middle East. "This finding provides an exciting new direction for Parkinson's disease research," says co-author Dr. Zbigniew Wszolek, a Mayo Clinic neuroscientist. "Every new gene we discover for Parkinson's disease opens up new ways to understand this complex disease, as well as potential ways of clinically managing it." The team found that mutation in VPS35, a protein responsible for recycling other proteins within cells, caused Parkinson's disease in the Swiss family. Mutated VPS35 may impair the ability of a cell to recycle proteins as needed, which could lead to the kind of errant buildup of protein seen in some Parkinson's disease brains and in other diseases like Alzheimer's disease, says co-author Dr. Owen Ross, a neuroscientist at Mayo Clinic in Florida. "In fact, expression of this gene has been shown to be reduced in Alzheimer's disease, and faulty recycling of proteins within cells has been linked to other neurodegenerative diseases," he says. So far, mutations in six genes have been linked to familial forms of Parkinson's disease, with many mutations identified as a direct result of Mayo Clinic's collaborative research efforts. Dr. Wszolek has built a worldwide network of Parkinson's disease investigators, many of whom have conducted research at Mayo Clinic. The study's first author, Dr. Carles Vilariño-Güell, and the senior investigator, Dr.

Scientists Discover New Role for Vitamin C in Retina, Posssibly Brain

Nerve cells in the eye require vitamin C in order to function properly — a surprising discovery that may mean vitamin C is required elsewhere in the brain for its proper functioning, according to a study by scientists at Oregon Health & Science University, and collaborators, published in the June 29, 2011 issue of the Journal of Neuroscience. "We found that cells in the retina need to be 'bathed' in relatively high doses of vitamin C, inside and out, to function properly," said Dr. Henrique von Gersdorff, a senior scientist at OHSU's Vollum Institute and a co-author of the study. "Because the retina is part of the central nervous system, this suggests there's likely an important role for vitamin C throughout our brains, to a degree we had not realized before." The brain has special receptors, called GABA-type receptors, that help modulate the rapid communication between cells in the brain. GABA receptors in the brain act as an inhibitory "brake" on excitatory neurons in the brain. The OHSU researchers found that these GABA-type receptors in the retinal cells stopped functioning properly when vitamin C was removed. Because retinal cells are a kind of very accessible brain cell, it's likely that GABA receptors elsewhere in the brain also require vitamin C to function properly, Dr. von Gersdorff said. And because vitamin C is a major natural antioxidant, it may be that it essentially 'preserves' the receptors and cells from premature breakdown, Dr. von Gersdorff said. The function of vitamin C in the brain is not well understood. In fact, when the human body is deprived of vitamin C, the vitamin stays in the brain longer than anyplace else in the body. "Perhaps the brain is the last place you want to lose vitamin C," Dr. von Gersdorff said.

July 8th

Discovery May Lead to New Treatment for Malignant Glioma

Cleveland Clinic researchers have identified a cellular pathway that cancer stem cells use to promote tumor growth in malignant glioma, an aggressive brain tumor. The research – published in the July 8, 2011 issue of Cell – also found that existing medications block this cancer-promoting pathway and delay glioma growth in animal models, suggesting a new treatment option for these often fatal brain tumors. Malignant gliomas account for more than half of the 35,000-plus primary malignant brain tumors diagnosed each year in the United States. Unfortunately, the outlook for patients with malignant gliomas is poor. For patients with the most severe, aggressive form of malignant glioma (grade IV glioma or glioblastoma multiforme), median survival is 9 to 15 months with the best available therapies. These treatments include surgery followed by radiation therapy with the chemotherapy temozolomide followed by additional temozolomide treatment. Although differences in tumors between people were known to exist, researchers have only recently begun to understand the importance of differences between cancer cells within the same patient. Groups of cells within a glioma which promote brain tumor formation in animal models – called cancer stem cells – have been identified. These cancer stem cells are often resistant to radiation and chemotherapy, making them an important target for developing new and effective disease treatments. In the recently published manuscript, a team of Cleveland Clinic researchers – led by Dr. Jeremy Rich, Chairman, and Dr. Anita Hjelmeland, of the Department of Stem Cell Biology and Regenerative Medicine of the Lerner Research Institute of Cleveland Clinic – define a novel molecular pathway that cancer stem cells use to promote tumor growth.

July 4th

Scientists Sequence Genome of Long-Lived, Cancer-Resistant Naked Mole-Rat

The naked mole-rat is native to the deserts of East Africa and has unique physical traits that allow it to survive in harsh environments for many years. It has a lack of pain sensation in its skin and has a low metabolic rate that allows it to live underground with limited oxygen supply. For the first time, scientists from the University of Liverpool and The Genome Analysis Centre (TGAC) in Norwich, UK, have sequenced the genome of the naked mole-rat to understand its longevity and resistance to diseases of aging. Researchers will use the genomic information to study the mechanisms thought to protect against the causes of aging, such as DNA repair and genes associated with these processes. To date, cancer has not been detected in the naked mole-rat. Recent studies have suggested that its cells possess anti-tumor capabilities that are not present in other rodents or in humans. Researchers at Liverpool are analyzing the genomic data and making it available to researchers in health sciences, providing information that could be relevant to studies in human aging and cancer. Dr. Joao Pedro Magalhaes, from the University of Liverpool's Institute of Integrative Biology, said: "The naked mole-rat has fascinated scientists for many years, but it wasn't until a few years ago that we discovered that it could live for such a long period of time. It is not much bigger than a mouse, which normally lives up to four years, and yet this particular underground rodent lives for three decades in good health. It is an interesting example of how much we still have to learn about the mechanisms of aging. We aim to use the naked mole-rat genome to understand the level of resistance it has to disease, particularly cancer, as this might give us more clues as to why some animals and humans are more prone to disease than others.

July 2nd

New Treatment Strategy for Usher Syndrome

Usher syndrome is the most common form of combined congenital deafness-blindness in humans and affects 1 in 6,000 of the population. It is a recessive inherited disease that is both clinically and genetically heterogeneous. In the most severe cases, patients are born deaf and begin to suffer from a degeneration of the retina in puberty, ultimately resulting in complete blindness. These patients experience major problems in their day-to-day lives. While hearing loss can be compensated for with hearing aids and cochlea implants, it has not proven possible to develop a treatment for the associated sight loss to date. Researchers at Johannes Gutenberg University Mainz (JGU) in Germany have now developed a new treatment approach to this disease. In previously conducted research into this subject, the research team headed by Professor Uwe Wolfrum of the Institute of Zoology at Mainz University had already gained insight into some of the fundamental molecular processes and mechanisms causing this debilitating syndrome. Using the results of this successful basic research, the Usher treatment team in Mainz headed by Dr. Kerstin Nagel-Wolfrum has now evaluated potential ocular treatment options. Their attention was focused on a mutation identified in a specific German family known to develop the most severe form of Usher syndrome. This mutation is a so-called nonsense mutation in the USH1C gene, which leads to the generation of a stop signal in a DNA sequence, resulting in premature termination of protein synthesis. The Mainz research team has now published its latest work on pharmacogenetic strategies for the treatment of Usher syndrome patients with nonsense mutations in the May edition of the journal Human Gene Therapy.

July 1st

New Class of Anti-Angiogenesis Drugs Identified

Massachusetts General Hospital (MGH) researchers and colleagues have discovered the first of an entirely new class of anti-angiogenesis drugs – agents that interfere with the development of blood vessels. In a June 27, 2011 report in Proceedings of the National Academy of Sciences/Early Edition, the investigators describe how a compound derived from a South American tree was able, through a novel mechanism, to interfere with blood vessel formation in animal models of normal development, wound healing, and tumor growth. "Most of the FDA-approved anti-angiogenesis drugs inhibit the pathway controlled by vascular endothelial growth factor or VEGF, which directly stimulates blood vessel development," says Dr. Igor Garkavtsev, of the Steele Laboratory for Tumor Biology at MGH, lead author of the study. "Although these drugs have become standard treatments for several types of cancer, they only provide modest benefit in terms of extending patient survival, so more effective drugs targeting tumor vasculature are needed." While tumors need to generate and maintain their own blood supply to keep growing, tumor vasculature tends to be highly disorganized, which interferes with the effectiveness of traditional treatments like radiation and chemotherapy. Drugs that target the VEGF pathway can "normalize" tumor vasculature and improve the effectiveness of other therapies, but in addition to their limited effect on patient survival, such agents also can generate resistance or have toxic effects. In their search for drugs that block blood vessel growth in different ways, Dr. Garkavtsev and his colleagues focused on pathways involved with the adhesion of endothelial cells that line blood vessels to the outer vessel wall.