Word: fragment
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...Some principles are not negotiable: the concept of national unity. If the guerrillas get what they want, it will fragment the country...
...beta amyloid--a generic name for a class of sticky proteins--from the brains of Alzheimer's patients. A short time later, four research teams zeroed in on the gene that encodes the recipe for making the protein. To their great surprise, they discovered that beta amyloid was a fragment of a much larger protein, which came to be known as the amyloid-precursor protein, or APP for short...
...Hospital Medical School screened the DNA of an Alzheimer's family and found what every geneticist in the field had been furiously looking for. The mutant APP gene sat on chromosome 21, and the single change in its DNA sequence occurred in the vicinity of the beta-amyloid fragment...
Then, last year, the Amyloid People staged a surprise attack. First, researchers at Elan Pharmaceuticals of South San Francisco stunned their colleagues by reporting that they had taken mice genetically engineered to develop plaques and vaccinated them with a fragment of beta amyloid. Twelve months later, seven out of nine mice remained plaque free. Then the Elan team vaccinated year-old mice whose brains were riddled with plaques. Result: the plaques started to melt away. Elan quickly drew up plans to test the vaccine in humans...
That same year, other research teams, including one led by Selkoe, created yet another stir. They zeroed in on the elusive enzymes that snip the beta-amyloid fragment from the precursor protein. "We had the paper, and now we had the scissors," says Selkoe. If he is right, one of those scissors, gamma secretase, may actually be the presenilin-1 protein. Whatever the true identity of gamma secretase turns out to be, pharmaceutical companies are rushing to develop drugs that block it. Bristol-Myers Squibb has already started safety tests of one such compound and hopes to expand its study...