評論
打印
Science and technology
科學技術
Drug research
藥物研究
Toxic medicine
毒類藥品
Snake venom is being used to cure, rather than kill
蛇毒用于治病，不是殺傷
THERE are no poisons, only poisonous doses.Thus did Paracelsus, the greatest of the alchemists, encapsulate an important piece of medical wisdom.
曾經最偉大的煉金術士帕拉塞爾蘇斯創立的一條重要的醫學名言如是說：沒有毒藥，只有毒劑。
In fact, that is only half the story,
然而，這只說對了一半。
for many materials which are toxic at high doses, when used sparingly and directed at specific targets, are not merely harmless, but actually beneficial.
很多物質量大了以后就有毒性了。當計量后專用時，不僅無害，而且有益。
Plant poisons, from digitalis to curare, are routinely employed as drugs.
一些植物的汁液，都可用作常規藥物。
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.
而現在研究人員轉向研究動物的毒液―蛇和蜥蜴分泌的毒汁，檢驗它們是否可用來治病。
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.
圈養的蛇可收集蛇毒。幾十年來，人們一直用蛇毒制作抗血清4治療毒蛇咬傷，還把它注射到綿羊和馬這樣哺乳動物體內，收取抗體。
Making drugs from the venom itself, however, is a fairly new idea.
雖然蛇毒制藥是一個全新的概念，
But that is what Stefan Hailey of the University of Delaware and his colleagues hope to do.
但特拉華州大學的史蒂芬?哈利和他們同事希望如此。
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，他們發表了一篇名為《毒素》的論文，介紹了從亞洲沙蝰的毒液中可以提取蛇毒蛋白質，這種蛋白質可激發人類免疫系統對抗惡性腫瘤。
Previous studies have shown that eristostatin stops melanoma cells colonising the liver and lungs in mice.
先前的研究發現蛇毒蛋白質能阻止黑色瘤細胞5在肝臟和肺的擴散。
Dr Hailey is trying to work out how this happens.
哈利正解密這一過程。
Eristostatin's day job is to stop victims' blood clotting and thus plugging up damaged blood vessels after a bite.
蛇毒蛋白質的功效是人被蛇咬傷后防止血液凝固堵塞血管。
By increasing blood loss, it weakens victims.
受傷者失血過多，逐漸虛弱。
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這種在血凝過程中起關鍵作用的細胞碎片，使其失效。
Dr Hailey hopes to make use of this tendency to encourage the immune system to attack melanoma cells.
哈利希望利用這種性質趨向激發免疫系統對抗黑色瘤細胞。
His idea requires eristostatin to be as attracted to cancer cells as it is to platelets.
他的理論需要蛇毒蛋白像抑制血小板那樣吸引癌細胞。
Two observations suggest it could be.
兩項研究結果證實了其可能性。
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.
一是蛇毒蛋白與黑素瘤細胞有一定的親和性，黑素瘤細胞表面可能有一種蛋白質，類似于讓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.
另一項是蛇毒蛋白附于細胞表面時，可吸引T形淋巴細胞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.
這些免疫系統細胞能吞噬被細菌感染的細胞或是癌化細胞。
If melanoma cells could, in this way, be made especially attractive to T-lymphocytes, that might clear away the tumour completely.
假如能讓黑素瘤細胞像這樣吸引T形淋巴細胞，那么就可能完全消除腫瘤。
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顯微鏡7技術研究黑素次瘤癌細胞與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.
這種技術可以調節原子力把兩者分開進行精確測量，看看是否真的存在吸引―經他證實是存在的。
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療癌癥，就會把它歸到不斷擴大的蛇毒提取藥類里。
Tirofiban, for instance, is a modified version of another anticoagulant—in this case from the venom of the African saw-scaled viper.
例如，欣維寧是從鋸鱗8的毒液中提取的，是改良了的抗凝劑。
It is given to people with angina, and also to those who have had heart attacks.
欣維寧針對心絞痛患者以及心臟病患者。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.
自然狀態下，存在于北美一種毒蜥―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可用于治療2型糖尿病10，因為它能增高高血糖患者體內的胰島素含量。
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―血管放松劑，廣泛用于治療高血壓。它由替普羅肽組成，從巴西箭頭毒蛇12提取，能加速毒液中毒素循環，迅速到達患處。
The year of the snake
蛇年
There are other venom-based drugs in the pipeline, too.
還有其它蛇毒提取藥物在研發。
Crotoxin, a protein from the South American rattlesnake, though not yet approved for use, may one day be employed to treat cancers.
響尾蛇蛋白是從南美響尾蛇中提取的一種蛋白質，雖然還沒有證實臨床效果，但有一天會用來治療癌癥。
Crotoxin seems particularly attracted to cancer cells.
響尾蛇蛋白表面看來特別能吸引癌細胞。
One portion of the molecule recognises a protein on the cell's membrane, and links to it.
響尾蛇蛋白分子的一部分能識別細胞膜，并依附其上。
The other portion damages the membrane, triggering a mechanism called apoptosis which causes the cell to kill itself.
另一部分能破壞細胞膜，產生一種讓細胞死亡13的機制。
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.
位于都柏林的凱爾特生物技術人員正進行一系列的實驗，用這種分子來治療巴黎皮蓬杜歐洲醫院的癌癥患者。
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.
今年他們計劃對患有不同種癌癥的患者進行治療，因為公司的研究人員相信治療固體腫瘤很有效果。
If those trials are successful, though, they then plan to concentrate on lung cancer, the largest market.
假如成功，他們就會專攻肺癌的治療。
Perhaps the most astonishing toxin-derived drug of all, however, is hannalgesin, which is made from king-cobra venom.
這是從眼鏡蛇王毒素中提取，可能是蛇毒提取藥中最療效最神奇的。
Kini Manjunatha of the National University of Singapore is developing this substance as a pain-relieving agent.
新加坡國大的齊尼教授正把這種物質研發成鎮痛劑。
He claims it is between 20 and 200 times more effective than morphine.
他說作用是嗎啡的20到200 多倍不等。
Moreover, unlike morphine, which is usually injected, hannalgesin can be taken by mouth.
再者，Hannalgesin不像嗎啡通過注射，可口服。
He is planning to run the first clinical trials at the end of 2013 or in early 2014.
他計劃于2013年底或2014年初進行首次臨床試驗。
Venom, then, is proving to be a trove of useful molecules.
經證實毒素就是有用的分子的集合。
At a time when drug companies are struggling to develop new products,
讓制藥公司通過自然選擇對原料進行驗證，研發新藥。
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.
這個新方法肯定受歡迎，因為不需要創新，而只是轉換了藥性。
It is not turning base metals into gold, as Paracelsus and his kind once attempted.
這個過程并不是像帕拉塞爾蘇斯這樣的術士們把賤金屬轉換成黃金，
But as a transformation of matter, it is surely a far more valuable trick.
但從物質轉換的角度來講，一定是價值連成。
