英語和漢語的表達(dá)方式有很大的區(qū)分點(diǎn)，所以很多考生在接觸到GRE閱讀文章的時(shí)候都需要一個(gè)轉(zhuǎn)換的過程。每天閱讀一篇優(yōu)質(zhì)的GRE雙語閱讀可以大大縮短轉(zhuǎn)換的時(shí)間，提高閱讀速度。下面是小編為大家整理的一篇關(guān)于GRE雙語閱讀：心臟疾病與微生物關(guān)系研究。

Heart disease and the microbiome —— High steaks

心臟疾病與微生物：牛排吃越多，心臟病風(fēng)險(xiǎn)越高

Hardening of the arteries may be caused by a malign interaction of meat-eating and intestinal bacteria

肉食與腸道細(xì)菌的惡性作用可能會(huì)造成動(dòng)脈硬化

THOSE who take part in clinical trials often have to do nasty things, from taking new drugs to forgoing sleep.

參加臨床試驗(yàn)的受試者常常得要做一些令人難受的事兒，從試用新藥到放棄睡眠。

Participants in a trial organised by Stanley Hazen of the Cleveland Clinic, in Ohio, had a decidedly easier task: eating steak.

克里夫蘭醫(yī)學(xué)中心的斯坦利 • 哈森在俄亥俄州組織的臨床試驗(yàn)中的受試者所要做的，相對(duì)來說要簡單的多：吃牛排。

After reading Dr Hazen's conclusions, though, they may be inclined to eat rather less of it.

但要是讀過哈森博士的實(shí)驗(yàn)報(bào)告后，他們或許寧愿自己少吃一些。

A link between red-meat consumption and heart disease was perceived by epidemiologists several decades ago, but the nature of this link has never been properly explained.

幾十年前就有流行病學(xué)家發(fā)現(xiàn)心臟疾病與食用紅肉有關(guān)，但這種關(guān)聯(lián)的原理一直沒有得到合理的解釋。

Blame's finger usually points at saturated fats and cholesterol.

飽和脂肪酸和膽固醇經(jīng)常被指責(zé)為引起心臟疾病的罪魁禍?zhǔn)住?/p>

Red meat contains both.

紅肉中這兩種物質(zhì)都有。

But a big recent study showed no connection between saturated fat and heart disease, so something else is probably involved.

較近一項(xiàng)大型研究發(fā)現(xiàn)飽和脂肪酸并不會(huì)引起心臟疾病，很可能是一些其他物質(zhì)引起的心臟疾病。

Dr Hazen thinks he knows what.

哈森博士認(rèn)為他發(fā)現(xiàn)了這些物質(zhì)是什么。

As he outlines in a paper just published in Nature Medicine, he believes the blame actually lies with the microbiome — the collection of 100 trillion or so bacteria that live in the human gut.

正如他在《自然醫(yī)學(xué)》上剛發(fā)表的文章中所說的那樣，他認(rèn)為罪魁禍?zhǔn)讓?shí)際上是微生物菌群 - 人體腸道中生存著大約 100 萬億細(xì)菌。

Generally, members of the microbiome get on well with their host.

一般來說，腸道菌群可與宿主和諧共處。

They digest complex carbohydrates that human enzymes cannot handle, thus increasing the nutritional value of food.

它們可分解人體中的酶所不能分解的復(fù)雜碳水化合物，因而可進(jìn)一步提高食物的營養(yǎng)價(jià)值。

They also fend off infections by hostile bugs.

它們還可阻擋病原菌對(duì)人體的侵害。

But, as with any partnership, the interests of the partners are not always in perfect alignment, and Dr Hazen thinks the processing of red meat is an example of such misalignment.

不過，像任何合作關(guān)系一樣，雙方的利益并不總是一致的，哈森博士認(rèn)為紅肉的消化吸收過程正是這種不一致的實(shí)例。

The mismatch in question revolves around a molecule called carnitine.

這種失衡主要是由一種叫做肉毒堿的化學(xué)物質(zhì)引起的。

This chemical helps transport fatty acids inside cells, and red meat is rich in it.

肉毒堿可參與運(yùn)輸細(xì)胞內(nèi)的脂肪酸，而紅肉中富含肉毒堿。

Dr Hazen thinks that when it is metabolised by gut bacteria, a chain of events begins that results in atherosclerosis.

哈森博士認(rèn)為腸道細(xì)菌代謝紅肉時(shí)，由此引發(fā)人體內(nèi)一連串的生物化學(xué)反應(yīng)，從而導(dǎo)致動(dòng)脈粥樣硬化。

A gut feeling

腸道感覺

Dr Hazen has already demonstrated, in a paper published in 2011, that parts of the microbiome can promote atherosclerosis.

哈森博士在他 2011 年發(fā)表的文章中驗(yàn)證，部分腸道菌群可促進(jìn)動(dòng)脈硬化。

In that paper he showed that choline, a molecule found in eggs and meat, is digested by some gut bacteria to produce trimethylamine, which is then processed in the liver to create trimethylamine N-oxide, or TMAO — a substance that encourages atherosclerosis.

他在文中指出膽堿—在蛋類和肉類中發(fā)現(xiàn)的一種分子，被腸道細(xì)菌消化吸收后生成三甲胺，三甲胺在肝臟中轉(zhuǎn)化為能夠加速動(dòng)脈硬化的三甲胺 N- 氧化物或氧化三甲胺。

That is bad in general.

這些化學(xué)物質(zhì)通常對(duì)人體是有害的。

And if the arteries in question are the coronary arteries, which supply heart muscle with blood, it is bad in particular because it can lead to a heart attack.

并且如果有損傷的動(dòng)脈是為心肌供血的冠狀動(dòng)脈，情況尤為糟糕，因?yàn)檫@將引起心臟病發(fā)作。

Carnitine is chemically similar to choline so, given its abundance in red meat, Dr Hazen wanted to know if it, too, might be linked with heart disease.

肉毒堿的化學(xué)作用與膽堿相似，由于肉毒堿在紅肉中含量豐富，哈森博士試圖通過實(shí)驗(yàn)探究肉毒堿是否也與心臟疾病有關(guān)聯(lián)。

He also wanted to know how TMAO wreaks its havoc on arteries.

同時(shí)他也想搞清楚氧化三甲胺是如何損傷動(dòng)脈血管的。

Attempting to answer these questions required several studies, on both mice and men.

為了得到答案，哈森博士對(duì)人和老鼠進(jìn)行了多項(xiàng)研究。

The first involved five human volunteers eating 8oz sirloin steaks, plus a carnitine supplement.

第一組實(shí)驗(yàn)的五個(gè)志愿者食用了 8 盎司沙朗牛排以及一片肉毒堿補(bǔ)充劑。

This diet resulted in high levels of both carnitine and TMAO in the volunteers' blood.

實(shí)驗(yàn)結(jié)果是，志愿者血液中都出現(xiàn)了高含量的肉毒堿和氧化三甲胺。

But when the same people were given antibiotics to kill their gut microbes, a subsequent steak meal produced little TMAO, even though their carnitine levels went even higher than before.

但當(dāng)這些志愿者食用可殺死腸道細(xì)菌的抗生素后，食用同樣的牛排卻只產(chǎn)生了少量的氧化三甲胺，盡管之前他們血液中肉毒堿含量升高過。

Production of TMAO, then, seems to need bacteria.

這表明氧化三甲胺的產(chǎn)生似乎確實(shí)需要腸道菌群參與。

Those bacteria are not, however, always present.

然而，這樣的腸道細(xì)菌并不總是存在的。

In the interests of science, Dr Hazen persuaded a vegan volunteer to eat a steak.

出于對(duì)科學(xué)真理的探索，哈森博士說服一名嚴(yán)格素食主義志愿者食用一塊牛排。

He compared this man's subsequent TMAO levels with those of a meat eater after a steak meal.

他將這位志愿者與食肉志愿者吃牛排后的血液中氧化三甲胺含量相比較，

The carnivore's TMAO levels jumped.

肉食志愿者的氧化三甲胺含量飆升，

The vegan's did not.

而素食志愿者的卻沒有。

That suggests the vegan's particular gut flora — adapted to his usual meat-free diet — did not contain species that can digest carnitine.

這表明素食者特有的腸道菌群—已經(jīng)適應(yīng)了他日常的素食飲食—不含可分解肉毒堿的細(xì)菌。

Some vegetarian volunteers, given carnitine pills but spared the steak, showed similar results.

一些素食志愿者沒吃牛排，但服用肉毒堿制劑，實(shí)驗(yàn)結(jié)果與吃牛排相似。

To find out whether all this matters, Dr Hazen looked at the association between heart disease and levels of carnitine and TMAO in more than 2,500 people.

為證實(shí)所有這些因素是否相關(guān)，哈森博士調(diào)查了 2500 多人，試圖發(fā)現(xiàn)心臟疾病與肉毒堿和氧化三甲胺之間的關(guān)系。

He found there was indeed an association between heart disease and carnitine, but only when TMAO levels were also high.

他發(fā)現(xiàn)心臟疾病確實(shí)與肉毒堿的含量有關(guān)，但只有當(dāng)氧化三甲苯含量也同樣很高時(shí)才可以。

Experiments in mice confirmed the broader hypothesis: TMAO production relies on microbes that digest carnitine, and prolonged consumption of that chemical by susceptible mice leads to atherosclerosis.

老鼠實(shí)驗(yàn)證實(shí)了進(jìn)一步的猜想：氧化三甲胺的產(chǎn)生需要分解肉毒堿的腸道細(xì)菌參與，易感小鼠如果長期食用肉毒堿會(huì)導(dǎo)致動(dòng)脈硬化。

Exactly how this happens is still hazy.

確切的作用機(jī)理目前尚不清楚。

Dr Hazen has shown, in yet further experiments on mice,that microbe-generated TMAO interferes with liver enzymes that make bile acids — substances that help remove excess cholesterol.

在接下來的老鼠實(shí)驗(yàn)中，哈森博士指出，細(xì)菌分解產(chǎn)生的氧化三甲胺可干擾產(chǎn)生膽汁酸的肝酶的活性—膽汁酸可幫助轉(zhuǎn)移多余的膽固醇。

TMAO also influences cholesterol metabolism in other parts of the body, including the artery wall.

氧化三甲胺還影響包括動(dòng)脈壁在內(nèi)的身體其他部位中的膽固醇代謝。

But the precise chain of events linking microbes to heart disease is still unclear.

但使得腸道細(xì)菌與心臟疾病有關(guān)的一系列相關(guān)的精確反應(yīng)至今還不清楚。

Another unknown is which of the microbiome's many species are responsible for promoting TMAO production.

腸道菌群中是否有很多種細(xì)菌參與氧化三甲胺的生成目前也并不明確。

Based on an analysis of the faeces of both vegetarians and meat eaters, Dr Hazen suspects bacteria of several genera, including Clostridium and Fusibacterium.

基于對(duì)素食與肉食志愿者的糞便研究，哈森博士猜想有幾種不同屬的細(xì)菌參與反應(yīng)，其中包括梭狀芽胞桿菌屬和梭菌屬。

Regardless of the details, though, this study suggests that people looking for the link between heart disease and the eating of meat have been ignoring two culprits, carnitine and bacteria.

但不論生化反應(yīng)細(xì)節(jié)如何，這項(xiàng)研究表明人們長期以來尋找心臟病與食肉之間的關(guān)聯(lián)，卻忽略了肉毒堿和腸道細(xì)菌這兩大元兇。

That does not absolve cholesterol of blame — on the contrary, carnitine boosts cholesterol's pernicious effect.

不過這并不意味著膽固醇是無害的—相反，肉毒堿的存在大大增長了膽固醇的害處。

But the study is yet another reminder that medical science's past failure to take proper account of humanity's bacterial guests has stopped researchers understanding how bodies actually work.

這項(xiàng)研究同時(shí)也提醒人們，之前醫(yī)學(xué)研究未能把人體腸道內(nèi)的細(xì)菌考慮在內(nèi)，使得研究者們沒能真正搞明白人體是如何運(yùn)轉(zhuǎn)的。

Heart disease is the biggest killer around.

現(xiàn)在心臟疾病是威脅人類健康的頭號(hào)殺手。

Though Dr Hazen's analysis does not change advice about how to prevent atherosclerosis, it may radically revise the treatment of those for whom prevention has failed.

雖然哈森博士的研究未能改變預(yù)防動(dòng)脈硬化的醫(yī)囑，但卻徹底改變了動(dòng)脈硬化患者的治療方案。