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By LIDIA WASOWICZ, UPI Senior Science Writer  |  Dec. 11, 2001 at 4:45 AM
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Scientists have used a combination of stem cell and gene therapy to partially regenerate the muscles of mice with Duchenne muscular dystrophy. The disease -- caused by a deficiency of the X chromosome gene dystrophin -- affects nearly solely boys and typically causes death from respiratory failure in the 20s. The research offers hope for some 250,000 Americans with muscular dystrophy, a group of genetic diseases that cause muscle weakness and wasting, said Johnny Huard of the University of Pittsburgh. He and his team isolated stem, or progenitor, cells from diseased mouse muscles, grew them in large numbers, fixed them with a corrective dystrophin gene and put them back into the mice. "If we could develop a similar type of therapy for people with muscular dystrophy -- using their own stem cells to deliver corrective genes to their muscles -- we could largely avoid problems with immune rejection," said Sharon Hesterlee, director of research development at the Muscular Dystrophy Association, which funded the work.


Scientists have long thought the AIDS virus, HIV, depletes its primary target, the immune system's CD4+ T cells, by blocking production of new cells. Two studies show otherwise. HIV does not block such production but instead accelerates the division of existing T cells, the researchers found. Highly active antiretroviral therapy results in a drop in the T-cell production rate and an even greater decrease in the rate of CD4+ T cell death, they said. The cell increases that follow the therapy are due to a slowdown in the loss of existing T cells, the study authors said. "These two studies have come to the same conclusion, namely that the primary cause of the immunodeficiency associated with HIV infection is an increase in the rate of CD4+ T-cell death," said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, which funded the studies. "This research sheds light on how we might best reduce the decline in those cells in the setting of HIV infection and more effectively treat people with HIV."


A protein similar to the blood molecule hemoglobin may offer protection against stroke, researchers say. The protein shares hemoglobin's affinity for oxygen, which the blood molecule helps transport to the body's tissues and organs. The newly found protein, dubbed neuroglobin because it was discovered in the brain, was the subject of a mouse study at the Buck Institute for Aging in Novato, Calif. The researchers grew brain cells and deprived them of oxygen, mimicking what happens in the brain of a stroke victim. They found that neuroglobin levels increased in the oxygen-deprived cells. The scientists blocked blood flow to the brain to simulate stroke in the mice. They found this also increased neuroglobin levels. They found that the stroke-induced cell damage was worse when the level of neuroglobin in the cells was reduced and less when it was increased, said lead author David Greenberg. Neuroglobin may be important in protecting brain cells from damage during a stroke, the authors concluded in the Proceedings of the National Academy of Sciences.


A yeast that preys on AIDS patients and others with compromised immune systems targets the disease-fighting system using what originally evolved as a defense against amoebae, say researchers at the Albert Einstein College of Medicine in New York. The yeast, Cryptococcus neoformans, invades the amoeba Acanthamoeba castellanii, dividing and ultimately killing the cell. It uses the same mechanism to infect amoeba-like cells that patrol the human immune system called macrophages. This helps answer how a fungus found in soil contaminated by pigeon droppings could infect and harm a human, the scientists say in the Proceedings of the National Academy of Sciences. The yeast causes meningitis in about 10 percent of AIDS patients. The results suggest the deadly effects are caused by mechanisms that evolved to protect the yeast against environmental predators such as amoebae, said lead author Arturo Casadevall.

(EDITORS: For more information about STEM, call 520-529-5317; about HIV, call 301-402-1663; about STROKE, 415-209-2087; about AIDS, call 608-262-6632.)

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