经济学人下载:药物研究 毒类药品

Science and technology
科学技术

Drug research
药物研究

Toxic medicine
毒类药品

Snake venom is being used to cure, rather than kill
蛇毒用于治病，不是杀伤

THERE are no poisons, only poisonous doses.Thus did Paracelsus, the greatest of the alchemists, encapsulate an important piece of medical wisdom.
曾经最伟大的炼金术士帕拉塞尔苏斯创立的一条重要的医学名言如是说：没有毒药，只有毒剂。

In fact, that is only half the story,
然而，这只说对了一半。

for many materials which are toxic at high doses, when used sparingly and directed at specific targets, are not merely harmless, but actually beneficial.
很多物质量大了以后就有毒性了。当计量后专用时，不仅无害，而且有益。

Plant poisons, from digitalis to curare, are routinely employed as drugs.
一些植物的汁液，都可用作常规药物。

And now it is the turn of animal toxins, as researchers examine venoms secreted by snakes and lizards, to see if they, too, might be turned into treatments.
而现在研究人员转向研究动物的毒液─蛇和蜥蜴分泌的毒汁，检验它们是否可用来治病。

Snake venom, collected from farmed reptiles, has been used to make antisera for snake bites for decades by injecting it into mammals such as sheep and horses, and collecting the antibodies thus generated.
圈养的蛇可收集蛇毒。几十年来，人们一直用蛇毒制作抗血清4治疗毒蛇咬伤，还把它注射到绵羊和马这样哺乳动物体内，收取抗体。

Making drugs from the venom itself, however, is a fairly new idea.
虽然蛇毒制药是一个全新的概念，

But that is what Stefan Hailey of the University of Delaware and his colleagues hope to do.
但特拉华州大学的史蒂芬?哈利和他们同事希望如此。

In a paper published recently by Toxicon, they report how a protein called eristostatin, which can be extracted from the venom of the Asian sand viper, helps people's immune systems fight malignant melanoma.
最近，他们发表了一篇名为《毒素》的论文，介绍了从亚洲沙蝰的毒液中可以提取蛇毒蛋白质，这种蛋白质可激发人类免疫系统对抗恶性肿瘤。

Previous studies have shown that eristostatin stops melanoma cells colonising the liver and lungs in mice.
先前的研究发现蛇毒蛋白质能阻止黑色瘤细胞5在肝脏和肺的扩散。

Dr Hailey is trying to work out how this happens.
哈利正解密这一过程。

Eristostatin's day job is to stop victims' blood clotting and thus plugging up damaged blood vessels after a bite.
蛇毒蛋白质的功效是人被蛇咬伤后防止血液凝固堵塞血管。

By increasing blood loss, it weakens victims.
受伤者失血过多，逐渐虚弱。

The molecule does this by glomming onto cellular fragments called platelets that are crucial to the process of clotting, thus disabling them.
抗凝分子能抑制血小板这种在血凝过程中起关键作用的细胞碎片，使其失效。

Dr Hailey hopes to make use of this tendency to encourage the immune system to attack melanoma cells.
哈利希望利用这种性质趋向激发免疫系统对抗黑色瘤细胞。

His idea requires eristostatin to be as attracted to cancer cells as it is to platelets.
他的理论需要蛇毒蛋白像抑制血小板那样吸引癌细胞。

Two observations suggest it could be.
两项研究结果证实了其可能性。

One is that eristostatin has a particular affinity for melanoma cells, which presumably have a protein on their surfaces that is similar to the one which attracts eristostatin to platelets.
一是蛇毒蛋白与黑素瘤细胞有一定的亲和性，黑素瘤细胞表面可能有一种蛋白质，类似于让蛇毒蛋白吸附血小板的蛋白。

The other observation is that when eristostatin is attached to a cell's surface it attracts the attention of T-lymphocytes.
另一项是蛇毒蛋白附于细胞表面时，可吸引T形淋巴细胞6。

These are immune-system cells whose job is to kill other body cells that have been infected with viruses, or which have turned cancerous.
这些免疫系统细胞能吞噬被细菌感染的细胞或是癌化细胞。

If melanoma cells could, in this way, be made especially attractive to T-lymphocytes, that might clear away the tumour completely.
假如能让黑素瘤细胞像这样吸引T形淋巴细胞，那么就可能完全消除肿瘤。

Dr Hailey and his colleagues used a technique called atomic-force microscopy to study the interactions between melanoma cancer cells and eristostatin.
哈利和其同事用原子力显微镜7技术研究黑素次瘤癌细胞与蛇毒蛋白的相互作用。

This technique allows the force required to pull the two apart to be measured precisely, to see whether there is a genuine attraction—which he found that there is.
这种技术可以调节原子力把两者分开进行精确测量，看看是否真的存在吸引─经他证实是存在的。

If eristostatin does prove an effective means to treat cancer, it will join a growing stable of medicines derived from reptile toxins.
假如蛇毒蛋白真能有效地治疗癌症，就会把它归到不断扩大的蛇毒提取药类里。

Tirofiban, for instance, is a modified version of another anticoagulant—in this case from the venom of the African saw-scaled viper.
例如，欣维宁是从锯鳞8的毒液中提取的，是改良了的抗凝剂。

It is given to people with angina, and also to those who have had heart attacks.
欣维宁针对心绞痛患者以及心脏病患者。依泰德森是人工的唾液素4。

Exenatide is the synthetic form of a hormone called exendin-4 that occurs naturally in the saliva of the Gila monster, a venomous North American lizard.
自然状态下，存在于北美一种毒蜥─希拉毒蜥的唾液中。

It works as a treatment for type-2 diabetes because it increases insulin production in those whose blood-sugar levels are high.
唾液素4可用于治疗2型糖尿病10，因为它能增高高血糖患者体内的胰岛素含量。

And captopril, a blood-vessel-relaxing agent widely used to treat hypertension, is based on teprotide, from Brazilian arrowhead vipers, which helps the other toxins in the venom circulate quickly, and thus reach their targets rapidly.
卡托普利11─血管放松剂，广泛用于治疗高血压。它由替普罗肽组成，从巴西箭头毒蛇12提取，能加速毒液中毒素循环，迅速到达患处。

The year of the snake
蛇年

There are other venom-based drugs in the pipeline, too.
还有其它蛇毒提取药物在研发。

Crotoxin, a protein from the South American rattlesnake, though not yet approved for use, may one day be employed to treat cancers.
响尾蛇蛋白是从南美响尾蛇中提取的一种蛋白质，虽然还没有证实临床效果，但有一天会用来治疗癌症。

Crotoxin seems particularly attracted to cancer cells.
响尾蛇蛋白表面看来特别能吸引癌细胞。

One portion of the molecule recognises a protein on the cell's membrane, and links to it.
响尾蛇蛋白分子的一部分能识别细胞膜，并依附其上。

The other portion damages the membrane, triggering a mechanism called apoptosis which causes the cell to kill itself.
另一部分能破坏细胞膜，产生一种让细胞死亡13的机制。

Celtic Biotech, based in Dublin, is running a series of tests using this molecule on cancer patients at the Georges Pompidou European Hospital in Paris.
位于都柏林的凯尔特生物技术人员正进行一系列的实验，用这种分子来治疗巴黎皮蓬杜欧洲医院的癌症患者。

This year, Celtic plans to try it on people with several different sorts of cancer, since the firm's researchers believe it should be effective on all solid tumours.
今年他们计划对患有不同种癌症的患者进行治疗，因为公司的研究人员相信治疗固体肿瘤很有效果。

If those trials are successful, though, they then plan to concentrate on lung cancer, the largest market.
假如成功，他们就会专攻肺癌的治疗。

Perhaps the most astonishing toxin-derived drug of all, however, is hannalgesin, which is made from king-cobra venom.
这是从眼镜蛇王毒素中提取，可能是蛇毒提取药中最疗效最神奇的。

Kini Manjunatha of the National University of Singapore is developing this substance as a pain-relieving agent.
新加坡国大的齐尼教授正把这种物质研发成镇痛剂。

He claims it is between 20 and 200 times more effective than morphine.
他说作用是吗啡的20到200 多倍不等。

Moreover, unlike morphine, which is usually injected, hannalgesin can be taken by mouth.
再者，Hannalgesin不像吗啡通过注射，可口服。

He is planning to run the first clinical trials at the end of 2013 or in early 2014.
他计划于2013年底或2014年初进行首次临床试验。

Venom, then, is proving to be a trove of useful molecules.
经证实毒素就是有用的分子的集合。

At a time when drug companies are struggling to develop new products,
让制药公司通过自然选择对原料进行验证，研发新药。

a novel source of raw materials that have been road-tested by natural selection, and merely need to be subverted from their original purposes rather than created afresh, must be welcome.
这个新方法肯定受欢迎，因为不需要创新，而只是转换了药性。

It is not turning base metals into gold, as Paracelsus and his kind once attempted.
这个过程并不是像帕拉塞尔苏斯这样的术士们把贱金属转换成黄金，

But as a transformation of matter, it is surely a far more valuable trick.
但从物质转换的角度来讲，一定是价值连成。