2013年12月英語六級外刊閱讀：挺過中風(fēng) 繼續(xù)活著

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　　Science and technology

　　科學(xué)技術(shù)

　　Surviving strokes

　　挺過中風(fēng)

　　Living on

　　繼續(xù)活著

　　Why some cells survive strokes while others don't

　　為什么有些細(xì)胞能幸免于中風(fēng)，而另一些則不能

　　WHEN dealing with a stroke—a loss of blood supply to the brain—time is of the essence.

　　在應(yīng)對由于大腦失去血液供應(yīng)造成的中風(fēng)時，時間是至關(guān)重要的。

　　If the cause is a blocked artery, blood flow can often be restored using clot-busting drugs.

　　如果原因是動脈阻塞，在使用溶栓藥物后，血液流動通常會恢復(fù)正常。

　　If those drugs are swallowed too late, however, they can do more harm than good.

　　然而，如果這些藥物吃得過晚，那么弊大于利。

　　In one of nature's crueller ironies, the metabolic changes that take place in cells after about three hours without oxygen or glucose mean that restoring blood flow becomes damaging in itself.

　　自然的殘酷諷刺是，細(xì)胞在約三個小時沒有氧氣或葡萄糖時所產(chǎn)生的代謝變化意味著恢復(fù)血流本身是具破壞性的。

　　This is called a reperfusion injury.

　　這就是所謂的再灌注損傷。

　　Doctors have long searched for ways to extend the period during which clot-busting pills might help.

　　醫(yī)生一直在尋找延長溶栓藥片作用時間的方法。

　　They have tried drugs and even artificially induced hypothermia to help the brain protect itself from the consequences of oxygen and sugar deprivation.

　　他們曾嘗試過麻醉劑，甚至人為地誘導(dǎo)低體溫以幫助大腦保護(hù)自身由于缺失氧氣和糖所造成的后果。

　　Now, in a paper in Nature Medicine, a group of researchers led by Alastair Buchan, a neurologist at the University of Oxford, describe a new idea.

　　目前，一篇由牛津大學(xué)神經(jīng)學(xué)家阿拉斯泰爾?巴肯所領(lǐng)導(dǎo)的一個研究小組在自然醫(yī)學(xué)雜志中發(fā)表的文章中，描述了一個新的想法。

　　Dr Buchan's team began with an old medical mystery.

　　但巴肯博士的團(tuán)隊是從一個古老的醫(yī)學(xué)之謎開始的。

　　It has been known since the 1920s that some nerve cells, or neurons, are more susceptible to stroke damage than others.

　　自20世紀(jì)20年代以來，就有人知道一些神經(jīng)細(xì)胞或神經(jīng)元比其他的更易遭中風(fēng)損傷。

　　In particular, a group of neurons called CA3 cells that live in the hippocampus—a seahorse-shaped chunk of brain tissue involved in forming memories—are much hardier than another sort called CA1 cells, even though the two types are neighbours.

　　特別是，一組存在于海馬狀突起中稱為CA3的細(xì)胞比另一種叫CA1細(xì)胞更具有耐受性，盡管這兩種細(xì)胞是彼此相鄰的。

　　Medical science is often concerned with working out why cells die, says Dr Buchan.We thought we'd look at why some seem to survive.

　　巴肯博士說：醫(yī)學(xué)經(jīng)常關(guān)注于解決細(xì)胞死亡的原因，我們想看看有些細(xì)胞幸存下來的原因。

　　The researchers compared versions of both types of cells taken from rats, looking for differences in their chemistry after they had been subjected to an artificial stroke.

　　研究人員比較了取自大鼠的這兩種類型細(xì)胞的變體，以找出它們在遭受人為中風(fēng)后化學(xué)成分的差異。

　　One conspicuous difference involved a protein called hamartin, which was present in larger amounts in the hardy CA3 cells than in the fragile CA1 cells.

　　一個顯著的區(qū)別在于一種名為錯構(gòu)瘤的蛋白質(zhì)，耐受性強(qiáng)的CA3細(xì)胞的錯構(gòu)瘤蛋白數(shù)量要比脆弱的CA1細(xì)胞中的多。

　　To check whether hamartin was indeed responsible for the CA3 cells' robustness, the researchers created in a test tube a strain of rat neurons which were unable to produce the protein, and then deprived them of oxygen and sugar for three hours.

　　為了檢驗是否錯構(gòu)瘤真的使CA3細(xì)胞變得更具耐受性，研究人員在試管中放入一株無法產(chǎn)生錯構(gòu)瘤的大鼠神經(jīng)元，然后使它們喪失三個小時的氧氣和糖。

　　Sure enough, cell deaths were about a third higher in the modified group than in the controls.

　　果然，改動組細(xì)胞的死亡率比對照組高出約三分之一。

　　Flipping the experiment around, neurons modified to produce more of the protein than usual had a stroke survival rate 31% higher than their unmodified counterparts.

　　再將該實(shí)驗反過來進(jìn)行，經(jīng)改良比平常產(chǎn)生更多蛋白質(zhì)的神經(jīng)元的中風(fēng)存活率比未經(jīng)改良的高出31%。

　　Experiments in rats themselves showed similar results.

　　在大鼠身上進(jìn)行的實(shí)驗也顯示出類似結(jié)果。

　　Hamartin, which is also known as a tumour suppressant, encourages a cellular recycling mechanism called autophagy.

　　錯構(gòu)瘤，也被稱為腫瘤抑制劑，能促進(jìn)被稱為細(xì)胞自噬的細(xì)胞再生機(jī)理。

　　This breaks down existing bits of cellular machinery so that their chemical components can be reused elsewhere.

　　它能夠分解現(xiàn)有的少量細(xì)胞組織以使這些細(xì)胞的化學(xué)成分可以在其他地方重新使用。

　　Autophagy presumably arose long ago as a way of helping cells survive lean times.

　　自噬大概很早以前就出現(xiàn)，作為一種幫助細(xì)胞在缺氧缺糖時存活下來的方式。

　　The theory is that such austerity measures also help neurons survive the hardscrabble environment of a blood-deprived brain.

　　該理論認(rèn)為，這種緊縮措施還有助于神經(jīng)元在大腦缺乏血液的貧瘠環(huán)境中存活下來。

　　So far, of course, the studies have been on rats rather than people.

　　當(dāng)然，到目前為止，這些研究僅在大鼠而不是人類身上進(jìn)行。

　　But the hippocampus is fairly similar across all of mammaldom.

　　但所有哺乳動物的海馬狀突起都完全類似。

　　Autophagy is a virtually universal property of cells in higher organisms, so it may well be worth investigating this process in other medical conditions in which organs are starved of blood, such as heart attacks.

　　細(xì)胞自噬實(shí)際上是高等生物的普遍特征，因此很值得研究它對缺乏血液的身體器官在其他身體狀況下的作用，比如心臟病發(fā)作時。

　　And because hamartin is already known to oncologists, some preliminary pharmaceutical groundwork has already been done.

　　因為錯構(gòu)瘤已為腫瘤學(xué)家所了解，一些初步的制藥基礎(chǔ)原理已經(jīng)完成。

　　Dr Buchan and his team are a long way from human trials, let alone a usable drug.

　　巴肯博士和他的團(tuán)隊離人體試驗還有很長的路要走，更不必說可用的藥物。

　　But they have turned up a promising lead.

　　但是，他們已經(jīng)找到了一個有希望的線索。

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