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  3. Fat: what is it good for? Absolutely nothing, or so you might think. But obesity seems to protect mice against a fatal form of m

Fat: what is it good for? Absolutely nothing, or so you might think. But obesity seems to protect mice against a fatal form of m

admin2015-12-23  81
问题     Fat: what is it good for? Absolutely nothing, or so you might think. But obesity seems to protect mice against a fatal form of malaria—cerebral malaria. Working out how it has this effect might lead to new treatments for people.
    Although obesity is now on the rise in the developing world, it has traditionally been seen as a malaise of the rich. In contrast, malaria tends to be regarded as a disease of the poor, so few people have studied how the two conditions affect each other. In mice meanwhile, there are signs that diabetes, which often affects obese people, might offer some protectioa against malaria.
    To find out more about how obesity affects malaria in mice, Vincent Robert at the Institute for Development Research(IRD)in Paris, France, and colleagues injected 14 obese and 14 non-obese mice with the malaria parasite Plasmodium berghei. After six days, eight of the non-obese mice died from cerebral malaria, which causes coma and death in humans, and the rest died about two weeks later from severe anemia because the parasite had destroyed their red blood cells. In contrast, none of the obese mice showed signs of cerebral malaria. Although they all eventually succumbed to severe anemia and died 18 to 25 days after infection, anemia can be treated—so obesity did seem to offer mice some useful protection.
    Exactly how the obese mice resist malaria is not clear, says Delphine Depoix from the Museum of Natural History in Paris, but there are several possibilities. One clue lies in a mutation in the gene coding for the leptin, a hormone produced by fat cells, which makes the mice obese, but also controls the immune response. Previous research has shown that obese mice with the leptin mutation often react to infections with a "Th2" rather man "Thl" response. As Thl in mice is thought to trigger the inflammation mat helps cerebral malaria to kill its victims, Depoix speculates mat me Th2 response might be protecting me obese mice. Another possible explanation is that the abnormally high blood sugar associated with obesity in both mice and people "might compensate" for the low blood sugar caused by severe malaria, says Depoix, allowing me mice to better cope with parasite infection.
    Andrew Prentice of the London School of Hygiene and Tropical Medicine says that figuring out how me mice resist malaria will be crucial to developing new treatments for people with malaria. His colleague Christopher Whitty warns that any insights drawn from these results are preliminary: "Mouse models are always useful in raising hypotheses but cannot settle them as far as cerebral malaria is concerned."
The first paragraph suggests that obesity
选项 A、has negative effect on me people.
B、appears helpful in protecting mice from cerebral malaria.
C、leads to new medical treatments for sick people.
D、does more good man harm to people.
答案B
解析 推理判断题。第一段提到肥胖似乎使老鼠免于感染脑型疟，故B项与之相符。A项“肥胖有负面影响”，与文意obesity seems to protect相悖；C项leads to逻辑混乱，并非是“肥胖能够导致新的治疗药物的产生”，而是通过研究肥胖为何能使老鼠免于感染疟疾，来找到治疗的药物；D项中的“益处多于害处”在该段找不到原文依据。
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