单选题
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 protection 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 than "Th1" response. As
Th1 in mice is thought to trigger the inflammation that helps cerebral malaria
to kill its victims, Depoix speculates that the Th2 response might be protecting
the 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 the mice to
better cope with parasite infection. Andrew Prentice of the
London School of Hygiene and Tropical Medicine says that figuring out how the
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."
单选题
The first paragraph suggests that obesity
A. has negative effect on the people.
B. appears helpful in protecting mice from cerebral malaria.
C. leads to new medical treatments for sick people.
D. does more good than harm to people.
【正确答案】
B
【答案解析】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。
单选题
Few people have conducted research on the relations between malaria and
obesity because
A. more and more people suffer from obesity in the developing world.
B. only a small number of the rich suffer from malaria.
C. both malaria and obesity are not prevalent in the world.
D. they were seen as the disease of the poor and of the rich
respectively.
【正确答案】
D
【答案解析】事实细节题。考查因果细节。第二段讲到由于两种疾病被看成两个不同群体(富人与穷人)所特有的疾病，所以很少有人关注肥胖与疟疾之间的联系，故D项正确。A项并非原因，仅是一个现象；B项并非原因，且only a small number是对原文内容的过度引申；C项not prevalent与文意“肥胖呈上升趋势”相悖，且与主干不构成因果关系。
单选题
After being injected with malaria parasite Plasmodium berghei, the
obese mice
A. died from cerebral malaria.
B. died from the destruction of their red blood cells caused by severe
anemia.
C. died from infection without showing signs of cerebral malaria.
D. were still alive thanks to the useful protection of obesity.
单选题
To which of the following statements would Delphine Depoix most
probably agree?
A. The obese mice are likely to give reaction to infections with a
"Th1"response.
B. The obese mice with the leptin mutation might be protected by "Th2"
response.
C. The inflammation triggered by Th2 helps cerebral malaria to kill its
victims.
D. Th1 in mice kills mice in a direct way.
【正确答案】
B
【答案解析】观点态度题。根据Delphine Depoix定位到第四段。研究发现，瘦素突变的肥胖老鼠经常对传染病做出Th2反应，而Th2反应可能保护肥胖的老鼠，故B项与之相符。A项“Th1”response与“通常对传染病做出Th2反应，而不是Th1反应”相悖；C项triggered by Th2与“Th1会诱发炎症”不符；文中提到，老鼠的Th1会诱发炎症，从而促使脑型疟置患者于死地，因此D项in a direct way错误。