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  劍6Test3雅思閱讀Passage3原文翻譯-尋找抗衰老藥

  The Search for the Anti-aging Pill

  尋找抗衰老藥

  In government laboratories and elsewhere, scientists are seeking a drug able to prolong life and youthful vigor. Studies of caloric restriction are showing the way

  在政府實(shí)驗(yàn)室等地，科學(xué)家們正在尋找能夠延長生命和保持青春活力的藥物。有關(guān)熱量限制的研究為我們指明了出路。

  As researchers on aging noted recently, no treatment on the market today has been proved to slow human aging — the build-up of molecular and cellular damage that increases vulnerability to infirmity as we grow older. But one intervention, consumption of a low-calorie*yet nutritionally balanced diet, works incredibly well in a broad range of animals, increasing longevity and prolonging good health. Those findings suggest that caloric restriction could delay aging and increase longevity in humans, too.

  衰老問題的研究者們最近指出，目前市面上還沒有任何療法證明可以延緩人類衰老。衰老是一種隨著年齡增長，人體內(nèi)分子與細(xì)胞損傷的累積導(dǎo)致人越來越虛弱的現(xiàn)象。然而，有一種干預(yù)措施對(duì)許多動(dòng)物都十分有效，那就是低熱量且營養(yǎng)均衡的飲食，它會(huì)延長實(shí)驗(yàn)動(dòng)物的壽命并維系健康。這些研究結(jié)果表明，限制熱量的攝取可能也會(huì)延緩衰老，延長人類的壽命。

  Unfortunately, for maximum benefit, people would probably have to reduce their caloric intake by roughly thirty per cent, equivalent to dropping from 2,500 calories a day to 1,750. Few mortals could stick to that harsh a regimen, especially for years on end. But what if someone could create a pill that mimicked the physiological effects of eating less without actually forcing people to eat less? Could such a ‘caloric-restriction mimetic’, as we call it, enable people to stay healthy longer, postponing age-related disorders (such as diabetes, arteriosclerosis, heart disease and cancer) until very late in life? Scientists first posed this question in the mid-1990s, after researchers came upon a chemical agent that in rodents seemed to reproduce many of caloric restriction’s benefits. No compound that would safely achieve the same feat in people has been found yet, but the search has been informative and has fanned hope that caloric-restriction (CR) mimetics can indeed be developed eventually.

  不幸的是，若想達(dá)到最佳效果，人們大概需要減少約30%卡路里的攝人量，相當(dāng)于從每天2500大卡降低到1750大卡。很少有人能夠堅(jiān)持這樣嚴(yán)格的養(yǎng)生之道，尤其是年復(fù)一年這樣做。但能不能制造出一種藥來模擬限食的生理效應(yīng)，而又不需要強(qiáng)迫人們少吃東西呢?這種被我們稱為“限食擬藥”的藥片是否能讓人們長久保持健康，延緩老年疾病(比如糖尿病、動(dòng)脈硬化癥、心臟病及癌癥)的發(fā)生，直到更老的時(shí)候?科學(xué)家們?cè)缭?0世紀(jì)90年代中期就提出了這個(gè)問題，此前研究者們偶然發(fā)現(xiàn)了一種化學(xué)藥劑，該藥劑似乎可以在嚙齒動(dòng)物身上產(chǎn)生限制熱量攝取的許多好處。至今我們還沒有發(fā)現(xiàn)能夠安全應(yīng)用到人類身上并達(dá)到同樣功效的藥物，但研究經(jīng)驗(yàn)助燃了希望之火，令我們相信，限食擬藥終究會(huì)研制出來的。

  The benefits of caloric restriction

  限制能量攝入的好處

  The hunt for CR mimetics grew out of a desire to better understand caloric restriction’s many effects on the body. Scientists first recognized the value of the practice more than 60 years ago, when they found that rats fed a low-calorie diet lived longer on average than free-feeding rats and also had a reduced incidence of conditions that become increasingly common in old age. What is more, some of the treated animals survived longer than the oldest-living animals in the control group, which means that the maximum lifespan (the oldest attainable age), not merely the normal lifespan, increased. Various interventions, such as infection-fighting drugs, can increase a population’s average survival time, but only approaches that slow the body’s rate of aging will increase the maximum lifespan.

  尋找限食擬藥的動(dòng)機(jī)是我們想更多地了解限制熱量攝取對(duì)身體的影響?？茖W(xué)家們?cè)缭?0多年前就已經(jīng)認(rèn)識(shí)到限制熱量攝人的益處。當(dāng)時(shí)，他們發(fā)現(xiàn)被喂食低熱量食物的鼠類平均壽命長于自由攝取食物的鼠類，而且也更少患鼠類衰老時(shí)的常見病。除此之外，食用低熱食物的鼠類活得比對(duì)照組中最老的鼠類還要長，這表明不僅是平均壽命，連最大壽命(可活的最大年齡)也增加了。盡管抗感染藥物等各種干預(yù)方法也可以增加種群的平均壽命，但只有通過降低身體衰老速率才能增加最大壽命。

  The rat findings have been replicated many times and extended to creatures ranging from yeast to fruit flies, worms, fish, spiders, mice and hamsters. Until fairly recently, the studies were limited to short-lived creatures genetically distant from humans. But caloric-restriction projects underway in two species more closely related to humans — rhesus and squirrel monkeys — have made scientists optimistic that CR mimetics could help people.

  鼠類的實(shí)驗(yàn)結(jié)果已經(jīng)重復(fù)過多次，而且對(duì)酵母菌、果蠅、蠕蟲、魚、蜘蛛、小鼠及倉鼠的實(shí)驗(yàn)也都有同樣的結(jié)果。迄今，這類研究針對(duì)的都只是與人類基因相去甚遠(yuǎn)的短命生物，然而，正在進(jìn)行中的研究采用了恒河猴與松鼠猴這兩種更接近人類的物種做實(shí)驗(yàn)對(duì)象，這使科學(xué)家們樂觀地相信限食擬藥可以幫助人類。

  The monkey projects demonstrate that, compared with control animals that eat normally, caloric-restricted monkeys have lower body temperatures and levels of the pancreatic hormone insulin, and they retain more youthful levels of certain hormones that tend to fall with age.

  對(duì)這些猴類的研究證實(shí)，比起正常飲食的對(duì)照組動(dòng)物，限制熱量攝人組猴子的體溫和胰島素濃度都較低，而且某些隨年齡增長而降低的荷爾蒙在他們體內(nèi)仍維持在年輕時(shí)的水平。

  The caloric-restricted animals also look better on indicators of risk for age-related diseases. For example, they have lower blood pressure and triglyceride levels (signifying a decreased likelihood of heart disease), and they have more normal blood glucose levels (pointing to a reduced risk for diabetes, which is marked by unusually high blood glucose levels). Further, it has recently been shown that rhesus monkeys kept on caloric-restricted diets for an extended time (nearly 15 years) have less chronic disease. They and the other monkeys must be followed still longer, however, to know whether low-calorie intake can increase both average and maximum life spans in monkeys. Unlike the multitude of elixirs being touted as the latest anti-aging cure, CR mimetics would alter fundamental processes that underlie aging. We aim to develop compounds that fool cells into activating maintenance and repair.

  在與衰老有關(guān)的疾病風(fēng)險(xiǎn)指數(shù)方面，這些熱量攝人受限的動(dòng)物看起來也更加健康。例如，它們的血壓與甘油三酸酷含量都比較低(表示得心臟病的可能性較小)，血糖濃度也比較正常(表示得糖尿病的風(fēng)險(xiǎn)較低，糖尿病的特征是高于常規(guī)的血糖濃度)。此外，有關(guān)研究最近指出，長期限制熱量攝人(將近15年)的恒河猴患慢性病的幾率也較低。但想要知道限制熱量攝人是否會(huì)延長猴類的平均壽命和最長壽命，我們還必須對(duì)這些恒河猴以及其他猴類做更長時(shí)間的跟蹤研究。與眾多被吹捧為最新抗衰老療法的長生不老藥不同，限食擬藥會(huì)改變衰老的基本進(jìn)程。我們的目標(biāo)是研制出能夠欺騙細(xì)胞進(jìn)人保養(yǎng)與修復(fù)狀態(tài)的藥物。

  How a prototype caloric-restriction mimetic works

  限食擬藥如何完成任務(wù)

  The best-studied candidate for a caloric-restriction mimetic, 2DG (2-deoxy-D-glucose), works by interfering with the way cells process glucose. It has proved toxic at some doses in animals and so cannot be used in humans. But it has demonstrated that chemicals can replicate the effects of caloric restriction; the trick is finding the right one.

  研究得最多、也是最有可能的限食擬藥是2DG(2-去氧-D-葡萄糖)，它是通過影響細(xì)胞中葡萄糖的代謝過程而發(fā)揮作用的。實(shí)驗(yàn)發(fā)現(xiàn)，達(dá)到某一劑量時(shí)，2DG會(huì)對(duì)動(dòng)物產(chǎn)生毒性，所以無法應(yīng)用到人類身上。盡管如此，這表明有些化學(xué)藥物的確可以模擬熱量攝人受限的效果;關(guān)鍵在于如何找到合適的藥物。

  Cells use the glucose from food to generate ATP (adenosine triphosphate), the molecule that powers many activities in the body. By limiting food intake, caloric restriction minimizes the amount of glucose entering cells and decreases ATP generation. When 2DG is administered to animals that eat normally, glucose reaches cells in abundance but the drug prevents most of it from being processed and thus reduces ATP synthesis. Researchers have proposed several explanations for why interruption of glucose processing and ATP production might retard aging. One possibility relates to the ATP-making machinery’s emission of free radicals, which are thought to contribute to aging and to such age-related diseases as cancer by damaging cells. Reduced operation of the machinery should limit their production and thereby constrain the damage. Another hypothesis suggests that decreased processing of glucose could indicate to cells that food is scarce (even if it isn’t) and induce them to shift into an anti-aging mode that emphasizes preservation of the organism over such ‘luxuries’ as growth and reproduction.

  細(xì)胞利用食物中的葡萄糖制造ATP(三磷酸腺苷)，該分子為身體的許多活動(dòng)提供能量。通過限制食物的攝取量，可使進(jìn)人細(xì)胞的葡萄糖降到最低，因此減少ATP的生成量。當(dāng)食量正常的實(shí)驗(yàn)動(dòng)物服用2DG時(shí)，葡萄糖大量進(jìn)人細(xì)胞，但2DG會(huì)阻止大部分葡萄糖的代謝，因而降低ATP的合成量。研究人員提出了幾種說法，解釋為什么妨礙葡萄糖代謝與ATP合成可以延級(jí)衰老。其中一種說法與ATP生成過程中自由基的釋放有關(guān)，人們認(rèn)為自由基會(huì)損傷細(xì)胞，因此導(dǎo)致衰老以及像癌癥這類與衰老有關(guān)的疾病。減少ATP生成機(jī)制的運(yùn)作次數(shù)可以限制自由基的數(shù)量，從而減少細(xì)胞受到的傷害。另一種假設(shè)認(rèn)為，葡萄糖代謝的降低讓細(xì)胞以為食物不足(即使事實(shí)并非如此)，而促使細(xì)胞進(jìn)人抗衰老的狀態(tài)，這種狀態(tài)著重的是機(jī)體本身的維持，而不是生長或繁殖這類“奢侈活動(dòng)”。

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