5. Bush Stem-Cell Estimate Cut From 64 to Fewer Than 10
In August of last year, President George W. Bush announced that scientists who received public research money could use only the human embryonic stem-cell lines that already exist—a decision that dismayed many researchers. At the time, Bush's advisers estimated there were 64 such populations. This year researchers discovered the actual number is "certainly less than 10" and probably no more than six, says Doug Melton, a molecular biologist at Harvard University and one of the scientists the president consulted before his decision. Melton had argued for unlimited stem-cell generation and use. The limited number of permissible cell lines left, Melton says, cannot meet the medical needs of a population as genetically diverse as the human race. Furthermore, stem-cell lines from mice begin to lose their ability to produce many types of cells after as few as 20 generations, and researchers assume the same will prove true for stem cells from humans. The policy, Melton says, "is like setting out on a cross-country trip and someone saying, 'OK, here are six gallons of gas.' You know immediately you are not going to get to the end." In April an administrative ruling from the National Institutes of Health offered some relief. The NIH announced that it would not penalize those who are using private funds to study stem cells by denying them public funds for other kinds of research. Melton and other researchers have already begun generating new cell lines. He says the ruling will ease the problem but is far from a panacea, especially because the vast majority of research is funded by the federal government. In September the British Parliament funded an embryonic-stem-cell bank that may eventually store thousands of cell lines, which will help make Britain a leader in embryonic-stem-cell research. Meanwhile, some scientists in the United States are moving to Britain. — Rabiya S. Tuma
40. Finally, a Test for Alzheimer's The symptoms of Alzheimer's disease creep slowly into a patient's life, gradually erasing thoughts and memories. Definitive proof of the disease, however, has been elusive. Until last year, both patient and doctor could only guess at what was happening inside the brain because they had no way—short of an autopsy—to see the damage. In July William Klunk and Chet Mathis, researchers at the University of Pittsburgh, and their collaborators in Uppsala, Sweden, announced that they had developed a radioactive compound that, when injected into the veins of a patient, travels to the brain and sticks to plaques of beta-amyloid protein, the telltale evidence of Alzheimer's disease. The compound, tested so far in only nine patients and five controls, can be detected by positron emission tomography, an imaging system similar to a CT scan. If the brain contains no clumps of beta-amyloid protein, the tracer molecules flush out quickly, and the researchers know that the affliction is not Alzheimer's. This discovery is more than a clinical tool, says Klunk, because it may ultimately allow doctors not only to map the extent of the damage but also determine if treatments are working. "I sometimes think of the ability to see amyloid in the brain as seeing the enemy. If you can see the enemy, then you can tell if the shots being fired are hitting their target and having an effect." — Rabiya S. Tuma
