雅思练习总结（二十一）

雅思练习总结（二十一）

本文章是雅思练习总结（二十一），总结了文章《The Search for the Anti-aging Pill》，内容包括原文精翻，文章脉络总结，单词扩展学习3个部分

1 文章原文及翻译

The Search for the Anti-aging Pill

翻译：抗衰老药片的研究进展

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

翻译：在政府实验室等研究机构中，科学家们正在寻找一种能够延长寿命和青春活力的药物。他们的研究表明，限制卡路里很有效

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.

翻译：正如衰老情况的研究人员最近指出的那样，目前市场上没有一种治疗方法能够减缓人类衰老，也就是分子和细胞损伤的累积，会导致我们随着年龄的增长而更容易患病。但有一种干预措施，即摄入较低水平的卡路里（食物能量值的量度）但营养均衡的饮食，对各种动物都非常有效，可以延长寿命并保持身体健康。这些发现表明，热量限制也可以延缓衰老并延长人类的寿命。

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.

翻译：不幸的是，为了获得最大益处，人们可能必须将热量摄入量减少约 30%，相当于从每天 2,500 卡路里减少到 1,750 卡路里。但是很少有人能坚持如此严苛的饮食方案，尤其是连续多年如此。但如果有人能制造出这么一种药丸，能模仿少吃的生理效果，而实际上又不强迫人们少吃，那会怎样？这种我们称之为“热量限制模拟药物”的东西能否使人们保持更长时间的健康，将与年龄相关的疾病（如糖尿病、动脉硬化、心脏病和癌症）推迟到晚年？科学家们在 20 世纪 90 年代中期首次提出了这个问题，当时研究人员偶然发现了一种化学物质，这种化学物质似乎可以在啮齿动物身上复现热量摄入限制的许多好处。目前还没有发现任何可以安全地在人类身上实现同样效果的化合物，但这一研究已经获得了丰富的信息，并让热量限制 (CR) 模拟物最终确实可以开发出来。

The benefits of caloric restriction

翻译：卡路里限制的优势

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.

翻译：寻找 CR 类似物的热忱，源于人们希望更好地了解热量限制对人体的诸多影响。科学家们在 60 多年前首次认识到这种方法的价值，当时他们发现，喂食低热量饮食的老鼠平均寿命比自由喂养的老鼠长，并且老年时越来越常见的疾病发病率也较低。更重要的是，一些接受治疗的动物比对照组中寿命最长的动物存活时间更长，这意味着不仅仅是这些动物的正常寿命增加了，它们的最大寿命也增加了。各种干预措施（例如抗感染药物）可以增加人群的平均存活时间，但只有减缓身体衰老速度的方法才能增加最大寿命。

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.

翻译：关于大鼠研究的结果已被多次重复，此外，这些研究已经被扩展到酵母、果蝇、蠕虫、鱼、蜘蛛、老鼠和仓鼠等各种生物。直到最近，这些研究还仅限于与人类基因上相距甚远的短命生物。但与人类关系更密切的两个物种——恒河猴和松鼠猴——身上进行的热量限制药物研究项目让科学家们乐观地认为热量限制模拟药物可以帮助人类。

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.

翻译：关于猴子的研究项目表明，与正常饮食的对照动物相比，热量摄入被限制的猴子们的体温和胰腺激素胰岛素水平较低，且它们可将某些会随着年龄的增长而下降的激素保持在更加活跃的水平。

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 lifespans 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.

翻译：被限制卡路里摄入的动物在与年龄有关的疾病风险指标方面也表现得更好。例如，它们的血压和甘油三酯水平较低（表明患心脏病的可能性降低），血糖水平也更正常（表明患糖尿病的风险降低，糖尿病的特点是血糖水平异常高）。此外，最近有研究表明，长期（近 15 年）限制热量饮食的恒河猴患慢性病的几率较低。而限制卡路里摄入量是否能增加猴子的平均寿命和最大寿命，还需要对限制组和对照组的其他猴子进行更长时间的跟踪观察。与被吹捧为最新抗衰老疗法的众多灵丹妙药不同，热量受限模拟药物会改变衰老的基本过程。研究人员的目标是开发出能够欺骗细胞激活维护和修复机制的化合物。

How a prototype caloric-restriction mimetic works

翻译：热量受限模拟药物的工作原理

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.

翻译：研究最为深入的热量受限模拟药物是 2DG（2-脱氧-D-葡萄糖），其作用机理是干扰细胞处理葡萄糖的方式。研究表明，某些剂量的 2DG 对动物有毒性，因此不能用于人类。但这一化合物的发现表明，化学物质具备热量限制的效果，因此目前问题的关键在于找到正确的化学物质。

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.

翻译：细胞利用食物中的葡萄糖来生成 ATP（三磷酸腺苷），这种分子为身体的许多活动提供能量。通过限制食物的摄入，卡路里的限制也可最大限度地减少进入细胞的葡萄糖量，并减少 ATP 的生成。当给正常饮食的动物服用 2DG 时，葡萄糖会大量进入细胞，但这种药物会阻止大部分葡萄糖被加工，从而减少 ATP 的合成。研究人员提出了几种解释，说明为什么中断葡萄糖加工和 ATP 生成可能会延缓衰老。一种可能的说法是：与 ATP 制造机制释放的自由基有关，人们认为，自由基会通过破坏细胞而导致衰老和癌症等与年龄有关的疾病。减少机器的运转应该会限制 ATP 的合成，从而抑制这种损害。另一种假设则认为，葡萄糖加工的减少可能向细胞发出食物稀缺的信息（即使事实并非如此），并诱导它们转向抗衰老模式，强调保存身体内的有机物，而不是发展生长和繁殖模式等饥饿状态下的奢侈品。

2 文章结构分析

文章的主要内容可总结为

1. 第一段、第二段是说，目前市场上没有一种治疗方法能够减缓人类衰老，摄入较低水平的卡路里（食物能量值的量度）但营养均衡的饮食，对各种动物都非常有效，可以延长寿命并保持身体健康，但是直接节食是很少有人能够坚持下来的，不过如果我们能通过合成一种化合物，让身体复现热量摄入限制的优势，就太好了

2. 第三段、第四段是说，人们一开始是在动物的身上发现了降低卡路里摄入水平对生物的优势的，在大鼠身上的研究表明，低卡路里摄入组的大鼠的老年病发病率更低，而且在平均寿命、最大寿命方面都有所增加。这一研究的意义在于发现，找到减缓身体衰老速度的方法才能增加人的最大寿命。而在其他动物，以及恒河猴和松鼠猴等人类近亲身上对于大鼠研究成果的复现，让此研究在人的身上起效出见曙光

3. 第五段、第六段是详细介绍了在猴子们身上的复现试验的成果：1 是热量摄入被限制的猴子们的体温和胰腺激素胰岛素水平较低，且它们可将某些会随着年龄的增长而下降的激素保持在更加活跃的水平；2 是血压和甘油三酯水平较低（表明患心脏病的可能性降低）；3 是血糖水平也更正常（表明患糖尿病的风险降低，糖尿病的特点是血糖水平异常高）；4 是长期（近 15 年）限制热量饮食的恒河猴患慢性病的几率较低；5 是限制卡路里摄入量是否能增加猴子的平均寿命和最大寿命，还需要对限制组和对照组的其他猴子进行更长时间的跟踪观察

4. 第七段、第八段是通过 2DG 这种研究最为深入的药物，介绍了这种机制背后的作用原理：1 总体来说，如果药物能干扰细胞处理葡萄糖的方式，就会有效。虽然这种物质达到一定剂量后，会有毒性，但这也表明，距离我们找到正确的化合物，不远了。2 细胞主要利用吸收的葡萄糖来合成 ATP，而 ATP 是身体主要的能量来源， 2DG 类似的化合物作用就是限制这种化合物的合成；3 阻止 ATP 的合成为什么会减缓衰老，有 2 种可能的说法，一是 ATP 制造的自由基会破坏细胞而导致衰老和癌症等与年龄有关的疾病，如果能限制 ATP 的合成，就可以抑制这种损害，二是葡萄糖加工的减少可能向细胞发出这具身体的食物稀缺的信息（即使事实并非如此），并诱导它们转向抗衰老模式，并专注于存储有机物，而不是生长和繁殖

文章整体结构如下