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HEALTH
American researchers discover gene preventing the regeneration of inner ear cells WASHINGTON- Researchers have identified a gene that prevents the regeneration of inner ear cells that are critical to hearing, a discovery experts say is the first step toward finding a way to correct the most common form of deafness among the elderly. In laboratory mouse studies at Massachusetts General Hospital, researchers found that by eliminating the effects of a single gene they could cause inner ear cells vital to hearing to regrow. The regrowth replaces nerve endings, called hair cells, that are often lost to injury or age. Most deafness is caused by the loss of these hair cells," said Zheng-Yi Chen, leader of the hospital research team. "Now we have the means to regenerate these cells." The goal, said Chen, is to find a way to turn off this gene in the inner ear of humans, probably with a drug, and allow the regrowth of hair cells. "That would lead to recovery of hearing," said Chen. He is senior author of the study appearing this week in the journal Science. Dr. James Battey, director of the U.S. National Institute of Deafness and Other Communication Disorders, one of the National Institutes of Health, said the discovery by Chen's team "is a very important first step toward learning" how to restore hearing in human patients. The hair cells are a key link in the signal chain that makes hearing possible. The cells line the cochlea, part of the inner ear that sends the sensation of sound to the brain. Sonic vibrations from the eardrum and bones of the middle ear are relayed to the cochlea where they excite the hair cells. This energy is converted to electrical signals that are carried by nerves to the brain and interpreted as sound. Humans are born with about 50,000 inner ear hair cells, but the cells decline over time due to injury, disease or age. Once enough of the cells die, then the hearing begins to fade because the cells do not naturally regenerate, said Stefan Heller, a hearing researcher at the Massachusetts Eye and Ear Infirmary. "Once these cells are lost they are lost for good," he said. "In profound deafness, you can get down to almost zero cells." Heller said the study by Chen's group is exciting to hearing researchers because "it shows for the first time that you can regenerate adult hair cells in the inner ear. If this leads to a drug that will do that, then it could be the cure (for deafness.)" The inner ear organ that controls balance also uses the hair cells and the gradual loss of these cells leads to balance disorders that are also common among the elderly. In the study, the research team surveyed all the genes that are active during the embryonic development of the inner ear. The researchers discovered that a protein made by the retinoblastoma, or Rb1, gene halted the growth of hair cells. In effect, they found that the Rb1 protein was a molecular switch that turned off hair cell proliferation. They then studied a mouse developed by Philip Hinds of the Tufts-New England Medical Center that did not express Rb1 protein in the inner ear. Mice lacking this gene tended to run in circles, suggesting an abnormality in the balance system. Researchers found that the animals had more hair cells in their inner ears than did mice with normal Rb1 genes and that the surplus cells were functional, capable of relaying electrical signals to the brain.
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Chen said he cultured hair cells that lacked the Rb1 gene and found that they did divide, growing new hair cells, and that the process stopped when the Rb1 protein was added. Although the studies were only in mice, Chen said the ear structure of the mouse is very similar to that of humans. The researchers now are screening chemicals that would neutralize the Rb1 protein and, thus, cause hair cells to grow.-Paul Rercer. Music can reduce pain MONTREAL, CANADA- Even the head-bobbing beat of a hip-hop track can offer pain relief to the genre's fans, suggests a study on the analgesic properties of music. Music has long been known to calm and relax. But a University of Montreal study suggests it doesn't merely provide a distraction from pain. It induces an emotional reaction among listeners that can diminish their pain by up to 15 per cent, the study found. The impact reflects an individual's musical tastes. Jazz fans may be best soothed by the trumpet sounds of legend Miles Davis while classical aficionados may find comfort in an orchestral masterpiece. "Our analyses showed that music the subjects liked had a significant effect on reducing their pain," said Mathieu Roy, 24, a doctoral student in neuropsychology. Roy exposed 80 university students to pain by attaching hot electrodes to their forearms. Various levels of discomfort were applied while subjects listened to six pre-selected instrumental musical pieces. The students said the pain diminished most in songs they liked and least when songs with harsh sounds were played or no music was played at all. "We think that by having a better understanding of the way by which music influences pain, it might help to be integrated into the clinical setting," said Roy, who next wants to study the impact of music on brain activity. Music therapy is just one of many efforts being undertaken to study non-pharmaceutical ways to help provide relief to the millions of Canadians who suffer chronic and acute pain. "Pain is a silent epidemic," said Celeste Johnston, past president of the Canadian Pain Society and associate director for research at the McGill School of Nursing. Canadians spent more than $2 billion last year on over-the-counter, herbal and prescription pain relief medication, say industry experts. About 17 per cent of Canadians suffer chronic pain from such ailments as osteoarthritis, lower pack pain, fibromyalgia, migraines and menstruation. Up to half of hospital patients are exposed to moderate to severe discomfort. Recent reports about the side-effects of COX-2 inhibitors like Vioxx and Celebrex and the addictive potential of OxyContin have spurred a public interest in alternatives, she said. "People are starting to realize that they can't take a pill that's going to fix everything." Researchers are also studying alternatives that were once considered taboo by the medical community, said Dr. Marc Ware of the McGill University Pain Centre. "There is unlikely to be a magic bullet," he said in an interview. "The approach for chronic pain is likely to be multidisciplinary and indeed integrative." In addition to drug therapy, alternatives include psychotherapy, relaxation techniques, physiotherapy, acupuncture, massage and yoga. A study of 170 patients at the Montreal pain centre points to the alternatives people are seeking. About 35 per cent use nutritional supplements including vitamins, 11 per cent turn to massage, 7.2 per cent to meditation, 6.5 per cent to glucosamine and five per cent to cannabis. While acupuncture was once considered experimental, recent studies confirm its usefulness for arthritis and migraines. Ware said physicians need to ensure natural remedies don't interfere with prescribed drugs. But they also need to further study alternatives to ensure nothing is overlooked in the quest to help patients. "With an aging population and with the demographics of our society, chronic pain is only going to continue to become a problem or to become a bigger problem, so we need to recognize it and tackle it," he said.-Ross Marrovitz.
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