医学考博英语阅读 | 感染病毒时宜进食，感染细菌时宜禁食

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读完本文的同学请在留言里回答，“强迫进食” 用英语怎么说？

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Science and technology: Medical treatment: Feed a virus, starve a bacterium

科学与技术：医疗：感染病毒时进食，感染细菌时禁食

An old wives’ tale gets some support from medical science.

无稽之谈获医学证实

Whether it is best to feed a fever and starve a cold, or vice versa, varies with the grandparent being asked. Medicine has decided that it is always a bad idea to deny food to the ill. Now a new study suggests that by ignoring such old wives’ tales, medics may have missed a trick.

是发烧时宜吃，伤风时宜饿呢，还是反之为佳？各家的爷爷奶奶对这个问题的回答是不一样的。医疗界已经判定，生病时拒绝进食总非良策。现有一项新研究表明，若忽视这类无稽之谈，医疗人员可能会错过机会。

A paper just published in Cell by a team of researchers led by Ruslan Medzhitov at Yale University suggest that force-feeding mice infected with influenza keeps them alive—but doing the same to mice with bacterial infections is fatal. Dr Medzhitov was inspired by experiments conducted not by medics, but by zoologists.

由耶鲁大学鲁斯兰·麦哲托夫带领的团队近日在《细胞》上发表的研究表明，患有流感的老鼠受到强行喂食尚能活命，而对有细菌感染的老鼠却是致命的。麦哲托夫博士受到动物学家（而非医生）所做的实验启发。

Most animals instinctively respond to infection by cutting back on food, and a slew of studies in recent years have shown that when diseased animals are force-fed they are more likely to die than if they are allowed to abstain.

大多数动物受到感染后，会本能地减少进食，并且近年来大量研究表明，强制给生病的动物喂食比允许其抑制进食更易致死。

But Dr Medzhitov wondered whether that held true for all types of disease. To investigate, he and his team infected one group of mice with a murine influenza virus, and the other with Listeria monocytogenes, a bacterium that causes food poisoning.

但麦哲托夫博士好奇这是否适用于各类疾病。为了进一步调查，麦哲托夫博士和他的团队使一组老鼠感染流感病毒，另一组感染能引发食物中毒的李斯特菌。

Some mice in each group were force-fed rodent chow, while others were force-fed nutrition-free saline. Every single mouse that was infected with the bacterium died if they were given food, but half survived on the saline.

每组中，给一部分老鼠强迫喂食鼠类饲料，而给另一部分老鼠注射无营养的生理盐水。感染细菌又被强迫喂食物的老鼠全部死亡，而被注射生理盐水的老鼠存活率达到一半。

The results of the viral infection were less stark, but still clear: 77.8% of infected mice survived if given food, but only 10% did so when given saline. One clue as to what might be going on lies in the fact, identified in earlier research, that cells infected with bacteria often prefer to burn fat instead of glucose, their usual fuel.

虽然病毒实验结果不那么残酷，但依然分明：其中被强迫喂食的老鼠存活率 77.8%，而被注射生理盐水的老鼠存活率仅为 10%. 导致这个结果可能的原因之一就在于受细菌感染的细胞通常倾向于燃烧脂肪而非葡萄糖 (平常的燃料)，这也得到早期研究的证实。

Further experiments led the team to confirm that glucose specifically was the key to survival in both viral and bacterial infections. As with the rodent chow, mice with bacterial infections that were fed glucose died.

进一步的实验使团队确定，葡萄糖在病毒感染和细菌感染中起到了性命攸关的作用。对感染细菌的老鼠喂食物或葡萄糖都致死。但当感染细菌的老鼠被喂食一类无法参与新陈代谢的葡萄糖时反而存活。

But infected mice fed a version of glucose that they could not metabolise lived. All of those fed the unusable variant of glucose died within ten days; 40% of those fed the ordinary stuff survived.

然而，受到病毒感染的老鼠结局几乎相反。被喂食无法食用的变异葡萄糖的老鼠在 10 天之内全部死亡，喂食普通食物的老鼠中则有 40% 存活下来。

The glucose seemed to make no difference to the bugs, nor to the immune systems of the mice. Instead, it altered the biology of the infected cells.

葡萄糖似乎对轻微的传染病和老鼠的免疫系统没有什么影响。相反，它转变了受感染细胞的机理。

In viral infections, many infested cells were committing suicide, a cellular scorched-earth strategy designed to slow the spread of the virus. Providing glucose seemed to bolster their ability to fight the infection without resorting to such drastic measures.

在病毒感染中，许多受感染的细胞都在自杀，这种焦土政策旨在减缓病毒的传播。而葡萄糖似乎只想要加强他们对抗感染的能力，而非诉诸于自杀这种极端的措施。

The opposite was true for bacteria. Burning fat protected infected mice. But swamping the cells with glucose caused them to produce prodigious quantities of highly reactive chemicals known as free radicals, which damage cells. That collateral damage made survival less likely.

相反，葡萄糖对细菌感染影响重大。燃烧脂肪保护了受感染的老鼠。但给细胞灌满葡萄糖会使它们产生数量庞大的高度活跃化学物质，即破坏细胞的自由基。这种附带损害使老鼠更难存活。

The precise biological details of why glucose is good for viral infections and bad for bacterial ones are not yet known. And Dr Medzhitov’s results will have to be tested in humans before medics can apply them. But they are a useful reminder that there is sometimes genuine wisdom hidden in folksy homilies.

葡萄糖对病毒感染有益却对细菌感染有害的具体生物学细节还尚未可知。在医护人员运用研究结果之前，麦哲托夫博士仍需要做临床试验。但这些成果依然有效地提醒人们：有时候民间俗语中还是蕴含着大智慧的。