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  3. Modern offices may scorn the stuff, but paper has found a new use in the laboratory — as the basis for 3D models of tumours and

Modern offices may scorn the stuff, but paper has found a new use in the laboratory — as the basis for 3D models of tumours and

admin2012-06-20  33
问题     Modern offices may scorn the stuff, but paper has found a new use in the laboratory — as the basis for 3D models of tumours and damaged hearts.
    Chemist George Whitesides and his colleagues at Harvard University reckon that the balls of cells they have grown at the centre of stacked paper could help us better understand how tumours and damaged hearts respond to drugs, and even to select therapies most suited to individuals.
    Cells tend to be grown on flat plates in the lab, which isn’t representative of the 3D structure of cells in the body. "It’s nothing like human tissue," says Whitesides. In our bodies, cells are exposed to natural concentration gradients: the further away they are from major blood vessels, the less oxygen and nutrients they get. But in 2D cell cultures, such gradients aren’t present. "We need to move away from those boring flatlands that cell culture dishes represent," says cell biologist Emmanuel Reynaud who was not involved in the research.
    Although techniques for growing cells in 3D exist, many are time-consuming and far from perfect. For example, once the cells have grown, the cultures need to be sliced with a knife to be analysed. "Not only does this kill some cells, it’s extremely difficult to do," Whitesides says. His group has now developed a cheap alternative.
    The team start by spraying a gel containing their cells onto small sheets of sterile chromatography paper (无菌色谱纸). The cells they used included human lung cancer cells, human fibroblasts (纤维原细胞), which make up connective tissue, and mouse immune cells. "I tried everything I could get my hands on," says Whitesides.
    The cells seeped through the paper "like coffee through a napkin (餐巾)", he says. When the researchers stacked up eight sheets of cell-infused paper and suspended them in an oxygen and nutrient-rich broth (液体培养基), they found that the cells grew into a ball.
    To analyse how these cells behaved, the researchers simply peeled off the layers one at a time and analysed them individually. It seemed that the outer cells closer to the medium were nourished while the cells on the inside showed signs of being starved, which is what you would expect to happen to a tumour inside the body.
The phrase "seeped through" (Line 1, Para. 6) is closest in meaning to______.
选项 A、disappeared gradually
B、spread and leaked through
C、broke through
D、passed and vanished gradually
答案B
解析 根据第六段中的like coffee through a napkin可知这里将细胞比作了咖啡，纸比作了纸巾。根据常识，咖啡洒在纸巾上应该扩散并渗入其中。选项中能表达这层含义的为[B]，故答案为[B]。
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