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Smoking causes wrinkles by upsetting the body" s mechanism for renewing skin, say scientists in Japan. Dermatologists say the finding confirms the long-held view that smoking ages skin prematurely. Skin stays healthy and young-looking because of a fine balance between two processes that are constantly at work. The first breaks-down old skin while the second makes new skin. The body breaks down the old skin with enzymes called matrix metalloproteinases, or MMPs, They chop up the fibers that form collagen(胶原质)—the connective tissue that makes up around 80 percent of normal skin. Akimichi Morita and his colleagues at Nagoya City University Medical School suspected that smoking disrupted the body" s natural process of breaking down old skin and renewing it. To test their idea, they first made a solution of cigarette smoke by pumping smoke through a saline(盐的)solution. Smoke was sucked from cigarettes for two seconds every minute. Tiny drops of this smoke solution were added to dishes of human fibroblasts, the skin cells that produce collagen. After a day in contact with smoke solution, the researchers tested the skin cells, to see how much collagen-degrading MMP they were making. Morita found that cells exposed to cigarette smoke had produced far more MMP than normal skin cells. Morita also tested the skin cells to see how much new collagen they were producing. He found that the smoke caused a drop in the production of fresh collagen by up to 40 percent. He says that this combined effect of degrading collagen more rapidly and producing less new collagen is probably what causes premature skin ageing in smokers, in both cases, the more concentrated the smoke solution the greater the effect on collagen. " This suggests the amount of collagen is important for skin ageing," he says. "It looks like less collagen means more wrinkle formation". Morita doesn" t know if this is the whole story of why smokers have more wrinkles. But he plans to confirm his findings by testing skin samples from smokers and non-smokers of various ages to see if the smoking has the same effect on collagen. "So far we" ve only done this in the lab. " he says. " We don"t know exactly what happens in the body yet that might take some time. " Other dermatologists are impressed by file work. "This is fascinating," says Lawrence Parish. Director of the Centre for International Dermatology at Thomas Jefferson University Hospital in Philadelphia. This confirms scientifically what we"ve long expected, he says. "Tobacco smoke is injurious to skin. " For the Japanese scientists, to test their idea is______.
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Are some people born clever and others born stupid Or is intelligence developed by our environment and our experiences Strangely【C1】______, the answer to both these questions is yes. To some extent our intelligence is given us at birth, and no amount of special education can make a genius【C2】______a child born with low intelligence. On the other hand, a child who lives in boring environment will develop his intelligence less than the one who lives in rich and varied surroundings. Thus the【C3】______of a person" s intelligence are fixed at birth, but whether or not he reaches those limits will depend on his【C4】______This view, not held by most experts, can be supported in a number of ways. It is easy to show that intelligence is to some extent【C5】______we are born with. The closer the blood relationship between two people, the closer they are likely to be in intelligence. Thus if we take two unrelated people【C6】______, it is likely that their degrees of intelligence will be completely different. If on the other hand we take two identical twins they will likely be as intelligent as each other. Relations like brothers and sisters, parents and children, usually have【C7】______intelligence and this clearly suggests that intelligence depends on birth. 【C8】______now that we take identical twins and put them in different environments. We might send one, for example to a university and the other to a factory where the work is boring. We would soon find differences in intelligence developing, and this indicates that environment【C9】______birth plays a part. This conclusion is also suggested by the【C10】______that people who live in close contact with each other,but who are not related at all, are likely to have similar degrees of intelligence. 【C3】
Smoking causes wrinkles by upsetting the body" s mechanism for renewing skin, say scientists in Japan. Dermatologists say the finding confirms the long-held view that smoking ages skin prematurely. Skin stays healthy and young-looking because of a fine balance between two processes that are constantly at work. The first breaks-down old skin while the second makes new skin. The body breaks down the old skin with enzymes called matrix metalloproteinases, or MMPs, They chop up the fibers that form collagen(胶原质)—the connective tissue that makes up around 80 percent of normal skin. Akimichi Morita and his colleagues at Nagoya City University Medical School suspected that smoking disrupted the body" s natural process of breaking down old skin and renewing it. To test their idea, they first made a solution of cigarette smoke by pumping smoke through a saline(盐的)solution. Smoke was sucked from cigarettes for two seconds every minute. Tiny drops of this smoke solution were added to dishes of human fibroblasts, the skin cells that produce collagen. After a day in contact with smoke solution, the researchers tested the skin cells, to see how much collagen-degrading MMP they were making. Morita found that cells exposed to cigarette smoke had produced far more MMP than normal skin cells. Morita also tested the skin cells to see how much new collagen they were producing. He found that the smoke caused a drop in the production of fresh collagen by up to 40 percent. He says that this combined effect of degrading collagen more rapidly and producing less new collagen is probably what causes premature skin ageing in smokers, in both cases, the more concentrated the smoke solution the greater the effect on collagen. " This suggests the amount of collagen is important for skin ageing," he says. "It looks like less collagen means more wrinkle formation". Morita doesn" t know if this is the whole story of why smokers have more wrinkles. But he plans to confirm his findings by testing skin samples from smokers and non-smokers of various ages to see if the smoking has the same effect on collagen. "So far we" ve only done this in the lab. " he says. " We don"t know exactly what happens in the body yet that might take some time. " Other dermatologists are impressed by file work. "This is fascinating," says Lawrence Parish. Director of the Centre for International Dermatology at Thomas Jefferson University Hospital in Philadelphia. This confirms scientifically what we"ve long expected, he says. "Tobacco smoke is injurious to skin. " Healthy skin lies in______.
Women find a masculine face—with a large jaw and a prominent brow—-more attractive when they are most likely to attractive, according to a study published in the June 24 NATURE. Before, during, and use after menstruation, however, they seem to be drawn to less angular, more "feminine" male faces, the researchers report. " Other studies of female preference, mainly for odors, show changes across the menstrual cycle ," says lead author Ian Penton-Voak of the University of St. Andrews in Scotland. " We thought it would be interesting to look at visual preferences and see if they changed also". The researchers showed 39 Japanese women composite male faces that emphasized masculine or feminine facial features to differing degrees. The women preferred images with more masculine features when they were in the fertile phase of their menses but favored more feminine features during their less fertile phase. The type of face women find attractive also seems to depend on the kind of relationship they wish to pursue, according to another experiment. The cyclic preference for muscular faces was evident among 23 British women asked to choose the most attractive face for a short-term relationship, Penton-Voak says. The 26 women asked to choose an attractive face for a long-term relationship, however, preferred the more feminine features throughout their menstrual cycle. Another 22 women who were using oral contraceptives did not show monthly changes in the faces they preferred even for short-term relationships, indicating that hormones might play a role in determining attractiveness, Penton-Voak says. Men whose faces have some feminine softness are perceived as " kinder" men who may make better husbands and partners, he adds, while macho features may be associated with higher testosterone(睾丸素)levels and good genes. He cautions, however, that research hasn"t yet shown a link between a woman" s preferences in such tests and her actual behavior. Women are drawn to a masculine face, according to the researchers, when they______.
Fourteen-year-old Sean MeCallum lay in a hospital bed waiting for a new heart. Without it, Scan would die. Sean" s case is not unusual. Everyday many people die because there just aren" t enough human organs to go around. Now scientists say they can alter the genetic make-up of certain animals so that their organs may be acceptable to humans. With this gene-altering technique to overcome our immune rejection to foreign organs, scientists hope to use pig hearts for transplants by the year 2008. That prospect, however, has stirred up strong opposition among animal fight activists. They protest that the whole idea of using animal organs is cruel and unjust; some scientists also fear such transplants may transform unknown diseases to humans. Others believe transplanting animal organs into humans is unnecessary. Millions of dollars spent on breeding pigs for their organs could be better spent on health education programs. They believe seventy-five percent of the heart disease cases that lead to a need for organ transplant are preventable. The key is to convince people to eat healthfully, and not to smoke or drink alcohol. Scientists could also use research funds to improve artificial organs. Still others believe that though new inventions and prevention programs may help, spending money to encourage more people to donate their organs is an even better idea. If enough people were educated about organ donations, everyone who needed an organ could be taken off the waiting list in a year. Doubtful of the necessity of using animal organs, some scientists______.
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