weeks. The genetic rejuvenation won't reverse other damage caused by time for the mouse, but could help its liver metabolize drugs or get rid of toxins.
Spindler's team fed three mice a normal diet for their whole lives, and fed another three on half-rations. Three more mice were switched from the normal diet to half-feed for a month when they were 34 months old—equivalent to about 70 human years.
The researchers checked the activity of 11,000 genes from the mouse livers, and found that 46 changed with age in the normally fed mice. The changes were associated with things like inflammation and free radical production—probably bad news for mouse health. In the mice that had dieted all their lives, 27 of those 46 genes continued to behave like young genes. But the most surprising finding was that the mice that only started dieting in old age also benefited from 70 per cent of these gene changes.
―This is the first indication that thee effects kick in pretty quickly,‖ says Huber Warner from the National Institute on Aging near Washington, D. C.
No one yet knows if calorie works in people as it does in mice, bus Spindler is hopeful. ―There's attracting and tempting evidence out there that it will work,‖ he says.
If it does work in people, there might be good reasons for rejuvenating the liver. As we get older, out bodies are les efficient at metabolizing drugs, for example. A brief period of time of dieting, says Spindler, could be enough to make sure a drug is effective.
But Spindler isn't sure the trade-off is worth it. ―The mice get less disease, they live longer but they're hungry,‖ he says. ―Even seeing what a diet does, it's still hard to go to a restaurant and say: 'I can only eat half of that'.‖
Spindler hopes we soon won't need to diet at all. His company, Life Span Genetics in California, is looking for drugs that have the effects of calorie restriction. 1. According to the passage, which of the following is NOT true? A. Eating less than usual might make us live longer. B. If we go on a diet when old, we may keep healthy. C. Dieting might not be needed.
D. We have to begin dieting from childhood.
2. Why does the author mention an elderly mouse in paragraph 2? A. To describe the influence of old age on mice. B. To illustrate the effect of meager food on mice. C. To tell us how mice's liver genes behave.
D. To inform us of the process of metabolizing drugs.
3. What can be inferred about completely normally fed mice mentioned in the passage?
A. They will not experience free radical production.
B. They will experience more genetic rejuvenation in their lifetime. C. They have more old liver genes to behave like young genes. D. They are more likely to suffer from inflammation.
4.According to the author, which of the following most interested the researchers?
A. The mice that started dieting in old age.
B. 27 of those 46 old genes that continued to behave like young genes. C. Calorie restriction that works in people. D. Dieting that makes sure a drug is effective.
5.According to the last two paragraphs, Spindler believes that A. calorie restriction is very important to young people
B. seeing the effect of a diet, people will eat less than normal. C. dieting is not a go0d method to give us health and a long life. D. drugs do not have the effects of calorie restriction.
第40篇New US Plan for Disease Prevention
Urging说服Americans to take responsibility for their health1 , Health and Human Services Secretary Tommy Thompson on Tuesday launched a$15 million program to try to encourage communities to do more to prevent chronic慢性的diseases like heart disease，cancer恶性肿瘤and diabetes.
The initiative highlights强调 the cost of chronic diseases - the leading causes of death in the United States—and outlines ways that people can prevent them，including better diet and increased exercise.
“In the United States today, 7 of 10 deaths and the vast majority of serious illness，disability残疾and health care costs are caused by chronic diseases, \and Human Services Department said in a statement.
The causes are often behavioral——smoking，poor eating habits and a lack of exercise.
“I am convinced确信 that preventing disease by promoting促进better health is a smart policy choice明智的选择for our future，”Thompson told a conference held to launch the initiative.
“Our current health care system is not structured构造 to deal with the escalating costs of treating diseases that are largely preventable through changes in our lifestyle choices.\
Thompson said heart disease and strokes will cost the country more than $351 billion in 2003.
“These leading causes of death for men and women are largely preventable，yet we as a nation are not taking the steps necessary for US to lead healthier, longer lives，”he said.
The $15 million is slated预定 to go to communities to promote促进prevention，pushing for changes as simple as building sidewalks to encourage people to walk more.
Daily exercise such as walking can prevent and even reverse heart disease and diabetes，and prevent cancer and strokes.
The money will also go to community organizations，clinics and nutritionists who are being encouraged to work together to educate people at risk of diabetes about what they can do to prevent it and encourage more cancer screening.
The American Cancer Society estimates估计 that half of all cancers can be caught by screening，including Pap tests for cervical cancer, mammograms for breast cancer, colonoscopies, and prostate checks.
If such cancers were all caught by early screening.the group estimates that the survival生存rate for cancer would rise to 95 percent.
词汇：diabetes [?dai?'bi:ti:z,-ti:s] 糖尿病 initiative [i'ni∫i?tiv] n.主动的行动，倡议 behavioral [b?'he?vj?r(?)l] adj.行为方面的 escalate ['esk?leit] vi.逐步上升;逐步增强 slate [sleit] vt.预定，规划
nutritionist [nju:`tr?∫?n?st] n.营养学家 cervical 's?:vik?l] adj.子宫颈的
mammogram ['m?m??ɡr?m] n. 乳房X射线照片 colonoscopy [,k??l?`n?sk?p?] n.结肠镜检查 prostate ['pr?steit] adj. 前列腺的
注释：1.take responsibility for their health ：承担起确保自己健康的责任 2.The initiative highlights the cost of chronic diseases ? ：这一行动强调了慢
性病所造成的损失??
3.Pap test (= Papanicolaou test):巴氏试验(一种检查早期癌变的方法) 练习：
1. Which of the following is NOT true of chronic diseases in the US?
A)They account for 70% of all deaths.
B)They are responsible for most of the health care costs. C)They often result in unhealthy lifestyles. D)They are largely preventable.
2.The author mentions all the following as ways of disease prevention EXCEPT A)better diet.
B)increased exercise. C)reduction on smoking.
D)higher survival rate for cancer.
3.The article indicates that more money spent on disease prevention will mean A)greater responsibility of the government.
B)much less money needed for disease treatment. C)higher costs of health care.
D)more 1ifestyle choices for people. 4.The $15 million program is aimed at A)promoting disease prevention. B)building more sidewalks. C)helping needy communities. D)wiping out chronic diseases.
5. Early cancer screening can help reduce significantly显著 A)the death rates for all chronic diseases. B)the kinds of cancer attacking people. C)the cancer incidence rate. D)cancer death rate.
答案与题解：
1. C 从文章的第三、六段分别可以看出，在美国，70%的死亡时由慢性病造成的，绝大多数医疗费用也花在慢性病的治疗上，而不健康的生活方式会引发慢性病，而不是慢性病引发不健康的生活方式。慢性病很大程度上是可以预防的。
2. D 从文章的第二、四段可以排除A、B和C三个选项。
3. B 从文章的第三、六、七段可以看出，慢性病的治疗花费极高。适当投资于疾病的预防可以大大减少这种花费。
4. A 从文章第一段可以看出，该项目的主要目的是促进疾病的预防。
5. D 从文章的最后一段可以看出，早期癌症检查有助于大大提高癌症存
第41篇 The Operation of International Airlines
International airlines have rediscovered the business traveler, the man or woman who regularly jets from country to country as part of the job. This does not necessarily mean that airlines ever abandoned their business travelers. Instead, companies like Lufthansa and Swissair would right argue that they have always catered best for the executive class passengers. But many airlines could be accused of concentrating too heavily in the recent past on attracting passengers by volume, often at the expense of the regular traveler. Too often, they have seemed geared for quantity rather than quality.
Operating a major airline is essentially a matter of finding the right mix of passengers. The airlines need to fill up the back end of their wide-bodied jets with low fare passengers, without forgetting that the front end should be filled with people who pay substantially more for their tickets.
It is no coincidence that the two major airline bankruptcies were among the companies specializing in cheap flights. But low fares require consistently full aircraft to make flights economically viable, and in the recent recession the volume of traffic has not grown. Equally the large number of airlines jostling for the available passengers has created a huge excess of capacity. The net result of excess capacity and cut-throat competition driving down fares had been to push some airlines into collapse and leave many others hovering on the brink.
Against this grim background, it is no surprise that airlines are turning increasingly towards the business travelers to improve their rates of return, They have invested much time and effort to establish exactly what the executive demands for sitting apart from the tourists.
High on the list of priorities is punctuality; an executive's time is money. In-flight service is another area where the airlines are jostling for the executive's attention. The free drinks and headsets and better food are all part of the lure.