Inside this issueCover storiesQuick study, big hearted contributorVan will bring much-needed mammography to Uganda's poorVessel researcher is appointed as new cardiovascular chiefPeopleExpert on RNA splicing wins Albany Medical Center PrizeLifelines: Richard Flavell
Doctor who stays in touch wins prize for clinical excellenceGenetics researcher is named inaugural Cohen ProfessorGenome authority is awarded Connecticut Medal of ScienceProfessor emeritus of public health is winner of Ivy AwardYale Medical Group physicians shine on latest ‘top docs’ listOut & aboutScienceType 1 diabetes: is prevention finally in sight?Yale lab hones virus that selectively kills brain tumor cellsAdvances: Lyme disease has European roots | Secrets of a stowaway bug | Testing neurons’ crossover potentialHealthOn-the-spot blood tests make surgery quicker
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AdvancesHealth and science news from YaleLyme disease has European roots
More than 20,000 cases of Lyme disease, a bacterial infection transmitted by deer ticks, are diagnosed each year in the U.S. Researchers have speculated that Borrelia burgdorferi, the spirochete that causes the clinical symptoms of Lyme disease seen in this country, originated in North America. But a new study published in the June 24 issue of Proceedings of the National Academy of Sciences traces the bacterium’s pedigree to Europe. Durland Fish, Ph.D., professor of epidemiology at the Yale School of Public Health, worked with an international team that analyzed 64 different samples of bacterial DNA from ticks and infected human patients in both the U.S. and Europe. By looking at mutations in a group of genes essential to basic metabolism, the scientists determined that European strains are more closely related to a common ancestor than are North American strains, indicating a European origin for the bacterium. “Understanding the evolution of pathogens is a key epidemiological tool,” says Fish. “By understanding the evolutionary history of pathogens, we can better predict their evolutionary future.” Secrets of a stowaway bugWhen harmful bacteria enter the body, white blood cells known as macrophages engulf them and sequester them in capsules called phagosomes. These capsules then fuse with lysosomes, spheres packed with enzymes that destroy the bacterium. But some bacteria can survive and continue to cause illness by blocking this process. Scientists have long known that pathogens like Legionella pneumophila, the cause of Legionnaire’s disease, secrete proteins into macrophages, but it has been unclear what those proteins do. In the June 20 issue of Science, a School of Medicine team led by Craig R. Roy, Ph.D., associate professor of microbial pathogenesis, reported that L. pneumophila proteins known as Anks disrupt the transport of endosomes—vesicles that eventually develop into bacteria-killing lysosomes—along intracellular conduits known as microtubules. Because L. pneumophila and related bacteria behave somewhat like viruses, in that they inject Ank proteins into cells, Roy says they might be vulnerable to a vaccine that targets Anks, allowing macrophages to do their job. Testing neurons’ crossover potential
As an embryo develops, wire-like axons sprout from cells, elongating to form networks of neurons in the brain and spinal cord. Some axons cross from one side of the body to the other, while others stay put. But how do axons know whether to cross? Scientists have shown that axons are prompted to cross the midline by an attractant protein known as netrin-1. Now a team led by Elke Stein, Ph.D., assistant professor of molecular, cellular and developmental biology and of cell biology, has shown that DSCAM (Down syndrome cell adhesion molecule), a protein that has been linked to mental retardation, is essential for netrin-1 to exert its effects on spinal axons. By suppressing the DSCAM gene in axons that normally cross at the midline of the mouse (see photo) and rat spinal cord during development, the Stein lab, in collaboration with Marc Tessier-Lavigne, Ph.D., of California-based Genentech, found that axons that lack DSCAM lose their “sense of direction”; they fail to grow and reach the midline. The Stein lab is now investigating whether DSCAM plays this essential role in wiring up other parts of the nervous system and the nature of its contribution to Down syndrome. A decline in fallsWhen taught how to prevent falls, clinicians and their older patients can significantly reduce the likelihood of one occurring. In an article published in The New England Journal of Medicine in July, Yale researchers reported an 11 percent reduction in the rate of older adults visiting an emergency department or being hospitalized because of a fall. The researchers compared injury rates in a 58-zip code area in and around Hartford—in which clinicians were encouraged to incorporate evidence-based fall risk assessment and management into their practices—to a control region elsewhere in Connecticut. Their analysis also showed 10 percent fewer fall-related hip fractures and head injuries, some 1,800 fewer emergency department visits or hospitalizations and overall health care savings in the study region estimated at $21 million over the two-year study period. “The research is done,” said senior author Mary E. Tinetti, M.D., the Gladys Phillips Crofoot Professor of Medicine and Epidemiology and Public Health. “The next step is to put it into practice, by making physicians, nurses and physical therapists everywhere more conscious of fall risks among their patients and of what can be done to prevent falls.”  |
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