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STEM CELLS If 2001 was the year of the embryonic stem cell, 2002 was the adult stem cell's turn. When President Bush stopped government funding for the creation of new stem-cell lines from embryos, researchers turned their attention to the next best thing--stem cells extracted from adult sources like bone marrow. Exactly how useful these adult cells will be for therapeutic purposes is a matter of intense debate. A Minnesota scientist reported that she was able to coax bone-marrow stem cells to act like embryonic stem cells, which in theory can give rise to any of the 200 cell types in the body. Other scientists fear that the apparent breakthrough may have been the result of laboratory contamination: in order to get the marrow cells to develop into other cell types, they needed to be mixed with embryonic stem cells.
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TAMOXIFEN Most women treated for breast cancer take tamoxifen to prevent the cancer from recurring, but it seems that for the drug to be most effective, timing is key. Until last year, most women with early-stage, estrogen-sensitive breast cancer had surgery followed by chemotherapy and tamoxifen. Tamoxifen blocks estrogen's cancer-promoting effects, but it turns out that the drug keeps chemotherapy agents from penetrating cancer cells and destroying them. An eight-year study of breast-cancer patients showed that women who waited to take tamoxifen until after their chemotherapy cycles were complete were 18% more likely to survive without a recurrence of cancer than women who took the two treatments together.
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VACCINES Why is autism 10 times as prevalent among young children today as it was in the 1980s? Many parents, noting that the onset of symptoms coincided with their child's vaccination against measles, mumps and rubella (MMR), are convinced that the mercury used as a preservative in the vaccine is to blame. But doctors have not been able to find a link, and now the results of a Danish survey of more than 500,000 children should finally put the theory to rest. The researchers found no difference in the incidence of autism between children who received MMR shots and those who did not. The more likely reasons for the increase: a broader definition of autism and greater awareness of its symptoms among doctors and parents.
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WEST NILE VIRUS Carried by birds on the wing, the West Nile virus continued its westward flight across the U.S. in 2002, killing more than 200 people in the largest outbreak of West Nile encephalitis in the world. Mosquitoes have been infecting birds and following them on their seasonal migration paths to 40 states. Even more worrisome, doctors learned for the first time that the virus can be passed from an infected mother to her unborn child. A girl born in November with brain abnormalities was the first in the U.S. to acquire West Nile encephalitis through intrauterine transmission.
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