MBA联考英语二模拟试题附答案详解(三)

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　　Ethosuzimide, which was developed in the 1950s, is commonly used to treat epilepsy, though it is no known precisely how the drug controls convulsions. There is no anecdotal evidence that it has had an anti-aglng effect in people. The next step, Komfeld says, is to test if the drugs have an anti-aging effect on animal like flies and mice.

　　Very little is known about the aging process. From genetic analysis, researchers have found that an in sulin-like signaling system regulates aging and longevity. A good diet can delay aging and extend a person life span. But scientists know virtually nothing about the effect of drugs on aging. “It’s a big void, ” Konfeld said.

　　In addition to delaying age-related degenerative changes, the drugs also increased neuromuscular activty, suggesting a link between the neuromuscular system and the aging process.

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　　There may also be other targets not yet explored that affect aging and neuromuscular function. Said Kornfeld: “The process of aging remains mysterious. ”

　　A. But Komfeld said scientists will not know about the applicability of the drugs in humans until a similar study is done on humans. “What’s very encouraging is that these drugs were developed to treat humans, and they are well understood, because they’ve been used for a long time, ” he said.

　　B. Later the scientists discovered that two related anticonvulsant drugs also lengthened the lives of the worms-in the case of one drug, by almost 50 percent. “This was a big surprise to use, Komfeld said. ”“We didn’t think anticonvulsant drugs had any particular relationship to aging. That connection was completely unexpected. ”

　　C. Roundworms are a poor subject for experiments, because they are not like humans, even though their molecules are similar. For example, they have no bones, nor do they show emotions, making it difficult to know how exactly human subjects would react to these drugs in large quantities. However, using the worms allows experiments to be conducted quickly, because they do not live for long.

　　D. “Somehow the neural activity seems to regulate the aging of all of the body the skin, musculature, and reproductive tract, ” Kornfeld said. “Somehow the nervous system coordinates the progress of all these tissues, evidently, though the life stages. But we don’t know how it does that. ”

　　E. The discovery may also shed light on the little-understood aging process. Since the drugs act on the neuromuscular systems of both humans and worms, the findings hint at a link between neural activity and aging.

　　F. Unlike vertebrates, the worms are ideal subjects for the study of aging because of their short life spans, which last only a couple of weeks in a laboratory. The worm is well known in genetics, and the worm’s genome has been sequenced.

　　G. Use of this drug has been permitted by law since 1998 and wider use is now expected as a result of the studies. “We can clearly link this drug with human aging, but we still need to find proof, says Kornfeld optimistically. ”

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