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SCIENCE&HEALTH: Surveying the damage of AIDS in the brain Computer imaging based on 3-D MRI scans shows decline of gray matter DAILY BRUIN REPORTER jguner@media.ucla.edu A recent imaging study by UCLA and University of Pittsburgh researchers, which revealed the areas of the brain damaged by the AIDS virus, may be used to determine which drugs better target the AIDS virus in the brain. The study, published by the Proceedings of the National Academy of Science online on Oct. 10, used magnetic resonance images to create 3-D scans depicting the motor and sensory regions of the brain that are selectively attacked by the AIDS virus. "There's really two main findings. One of them is a big surprise that HIV is very selective in how it damages the brain," said Paul Thompson, associate professor in the department of neurology at the UCLA David Geffen School of Medicine and a lead researcher. "The second surprise is that the drugs don't save brain tissue," he said. The researchers found no difference in tissue loss between AIDS patients taking antiretroviral drugs and AIDS patients who were not taking the drugs. Although antiretroviral drugs are effective in regulating the AIDS virus, the virus is still able to kill neurons in the brain. About 15 percent of gray matter in regions related to motor, language and sensory function were destroyed in the patients that were studied. This gray matter is the location of the neurons that the AIDS virus kills. Other regions of the brain generally remained intact. This loss in gray matter can result in mild cognitive damage such as difficulty concentrating and slower reaction times. About 40 percent of AIDS patients experience such cognitive impairment, Thompson said. However, the imaging technique designed by the research group can be used in drug trials to view how effective new drugs will be in minimizing brain tissue damage. "There is hope. Now that patients are living much longer with HIV the focus turns to saving brain tissue from damage ... Even if you lose about 1 percent brain tissue per year we might be able to prevent the damage with better drugs along the way," Thompson said. The research group developed a new method of measuring the thickness of gray matter. A computer is used to measure the thickness of gray matter based on 3-D MRI scans, which use radio frequency waves and magnetic fields to excite atoms and generate an image. Color images of the scans are then produced to show which areas of the brain are targeted by the virus. "The brain is thinner in parts of the brain that control motor skills and sensory functions," said Oscar Lopez, associate professor of neurology at the University of Pittsburgh and a member of the research team. "These imaging techniques can be used to track the progress of AIDS and in evaluating the effects of new drugs," he said. Although antiretroviral drugs are able to eliminate the majority of the HIV/AIDS virus in the bloodstream, some of these drugs have trouble passing the blood-brain barrier which is inhibitory to most drugs. Certain drugs can, however, pass the barrier. "When you put people on potent viral drug therapies, the virus is hiding in the central nervous system of the brain ... We could get rid of 99.9 percent of the virus in people's blood and they still wouldn't be cured," said Edwin Bayrd, executive director of the UCLA AIDS Institute. The imaging technique developed by the research group will allow scientists to determine which drugs are most effective at targeting the viruses residing in the brain. "These are really the first pictures of where the virus does damage," said Thompson. The first incidence of AIDS in the United States was documented in Los Angeles in 1981. The first patients diagnosed with AIDS were treated at UCLA Medical Center. The virus spread throughout the country by 1982. About 40 million people worldwide are infected with HIV or AIDS. |
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