The 2015 Nobel prizes: Physiology or
medicine- 2015年諾貝爾獎-生理醫學獎得主-
Researchers share honour for
finding ways that nature can provide solutions to its own problems-本年度由美、中、日三國科學家分享殊榮- 用大自然的力量征服大自然的危害(以毒攻毒法)。
DESPITE what the romantic
poets would have you believe, the natural world is not
a friendly place. It is full of dangerous creatures, and some of the
most dangerous are the smallest: the bacteria,
viruses and parasites that
between them debilitate (weaken) and
kill millions of people every year. But it is possible, with a bit of cunning,
a bit of luck and a lot of hard work, to turn a bit
of nature against itself—to humanity's benefit. And it is for
exactly this sort of work that Sweden's Royal Academy of Sciences has awarded
the 2015 Nobel prize in physiology or medicine.
The three winners are
William Campbell, Satoshi Omura (大村) and Tu Youyou. (杜友友) Drs Campbell and Omura were honoured for their
discovery of avermectin, a drug that kills the parasitic worms (寄生菌) responsible for river blindness and lymphatic
filariasis (淋巴絲蟲病), and which between them infect about 125m people
worldwide. Dr Tu—who originally trained in traditional Chinese
medicine—discovered artemisinin,(苦艾草類屬) a drug that helps kill the parasite that causes
malaria (瘧疾). Around 200m people are thought to be infected
with malaria, and about half a million die each year.
Dr Omura is a microbiologist(微生物學家) by training. His research at Kitasato University, in
Japan, focused on a genus of bacteria (細菌屬類) called Streptomyces,(鏈球菌) which were known to produce
complex chemicals that seemed to be able to weaken and kill rival
micro-organisms. (微生物) Streptomycin,(鏈球菌抗生素) an early antibiotic and
one of the first effective treatments for tuberculosis (肺結核), is, as its name suggests, derived from Streptomyces.
Selman Waksman, its discoverer, won the Nobel prize for medicine in 1952. Dr
Omura developed ways of growing Streptomyces bacteria in the
lab, allowing him to systematically culture (培養) thousands of strains(菌屬) and screen(過篩分級) them to see whether any of
those compounds(化合物) might hold medical promise.(醫療用這的遠景)
鏈球菌 avermectin(獸醫用-除寄生菌注射劑
Dr Campbell, then of Drew
University in New Jersey, heard of Dr Omura's work and managed to obtain
samples of his most promising bugs. An expert in parasite physiology, he was
able to demonstrate that a certain chemical extracted from Dr Omura's bacteria
was indeed effective at killing parasites in animals. It was isolated and
dubbed(轉錄)avermectin; after further lab work, a slightly
chemically modified version called ivermectin was produced for human
consumption. These days ivermectin is listed by the World Health Organisation (WHO) on its List of Essential Medicines, which
catalogues the drugs that even the most basic medical system needs.
Whereas avermectin is derived from bacteria, artemisinin
comes from plants. Its discovery was the consequence of Project 523, a
secretive military operation run by the Chinese government at the request of Ho
Chi Minh(胡志明)during the Vietnam War. The hope was to find new
treatments for malaria, which is thought to have killed more soldiers than the
bullets and bombs of the war itself. Artemisia annua,(苦艾草)or sweet wormwood, was one of the plants screened by the
programme's scientists, using a list of thousands of compounds used in
traditional medicine.
苦艾草
Folk doctors had long
suspected the plant had anti-malarial properties(抗瘧疾特性): the first record of its use dates back to "The
Handbook of Prescriptions for Emergencies", (急救手冊) written in 340 BC by an alchemist(煉丹士) and writer called Ge Hong.(葛洪)
Dr Tu helped to confirm that
the plant did indeed have anti-malarial properties, was able to isolate the
compound responsible, and developed a way to extract it in bulk. Anti-malarial
drugs derived from artemisinin became available just as the malaria parasite
was beginning to evolve resistance to chloroquine (奎因-抗瘧疾藥) and quinine, (奎寧) two older treatments.
These days it and its derivatives are the treatment of choice for the disease.
左：奎寧植物 右：瘧疾症狀(乾咳、全身發冷發熱、噁心、嘔吐、脾臟擴大等)
Even today, and even with
drugs readily available, millions of people, mostly in poor countries, are dogged (受侵襲) by parasitic infections. Malaria in particular remains a
public health disaster, killing half a million people a year and burdening
hundreds of millions more with a debilitating, painful disease. Yet the outlook
is better than is often supposed: the WHO says that by 2013, malaria deaths had
fallen by 47% compared with 2000. Some
countries, notably India, talk of eliminating the disease entirely from within
their borders. Similarly, river blindness used to be one of the leading causes
of preventable blindness; these days doctors talk cautiously, but optimistically, of the possibility of extirpating (澈底消滅) the disease entirely from the Earth. Doing that will
take money, determination and political will—but it would not be possible at
all without the drugs that Drs Campbell, Omura and Tu helped to discover.
Justin Lai 加注中文及圖示
10/06/2015/全
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