《经济学人》杂志原版英文(整理完整版)

1、.Digest Of The. Economist. 2006(6-7)Hard to digestA wealth of genetic information is to be found in the human gutBACTERIA, like people, can be divided into friend and foe. Inspired by evidence that the friendly sort may help with a range of ailments, many people consume bacteria in the form of yogur

2、ts and dietary supplements. Such a smattering of artificial additions, however, represents but a drop in the ocean. There are at least 800 types of bacteria living in the human gut. And research by Steven Gill of the Institute for Genomic Research in Rockville, Maryland, and his colleagues, publishe

3、d in this weeks Science, suggests that the collective genome of these organisms is so large that it contains 100 times as many genes as the human genome itself. Dr Gill and his team were able to come to this conclusion by extracting bacterial DNA from the faeces of two volunteers. Because of the com

4、plexity of the samples, they were not able to reconstruct the entire genomes of each of the gut bacteria, just the individual genes. But that allowed them to make an estimate of numbers. What all these bacteria are doing is tricky to identifythe bacteria themselves are difficult to cultivate. So the

5、 researchers guessed at what they might be up to by comparing the genes they discovered with published databases of genes whose functions are already known. This comparison helped Dr Gill identify for the first time the probable enzymatic processes by which bacteria help humans to digest the complex

6、 carbohydrates in plants. The bacteria also contain a plentiful supply of genes involved in the synthesis of chemicals essential to human lifeincluding two B vitamins and certain essential amino acidsalthough the team merely showed that these metabolic pathways exist rather than proving that they ar

7、e used. Nevertheless, the pathways they found leave humans looking more like ruminants: animals such as goats and sheep that use bacteria to break down otherwise indigestible matter in the plants they eat. The broader conclusion Dr Gill draws is that people are superorganisms whose metabolism repres

8、ents an amalgamation of human and microbial attributes. The notion of a superorganism has emerged before, as researchers in other fields have come to view humans as having a diverse internal ecosystem. This, suggest some, will be crucial to the success of personalised medicine, as different people w

9、ill have different responses to drugs, depending on their microbial flora. Accordingly, the next step, says Dr Gill, is to see how microbial populations vary between people of different ages, backgrounds and diets. Another area of research is the process by which these helpful bacteria first colonis

10、e the digestive tract. Babies acquire their gut flora as they pass down the birth canal and take a gene-filled gulp of their mothers vaginal and faecal flora. It might not be the most delicious of first meals, but it could well be an important one.Zapping the bluesThe rebirth of electric-shock treat

11、ment ELECTRICITY has long been used to treat medical disorders. As early as the second century AD, Galen, a Greek physician, recommended the use of electric eels for treating headaches and facial pain. In the 1930s Ugo Cerletti and Lucio Bini, two Italian psychiatrists, used electroconvulsive therap

12、y to treat schizophrenia. These days, such rigorous techniques are practised less widely. But researchers are still investigating how a gentler electric therapy appears to treat depression. Vagus-nerve stimulation, to give it its proper name, was originally developed to treat severe epilepsy. It req

13、uires a pacemaker-like device to be implanted in a patients chest and wires from it threaded up to the vagus nerve on the left side of his neck. In the normal course of events, this provides an electrical pulse to the vagus nerve for 30 seconds every five minutes. This treatment does not always work

14、, but in some cases where it failed (the number of epileptic seizures experienced by a patient remaining the same), that patient nevertheless reported feeling much better after receiving the implant. This secondary effect led to trials for treating depression and, in 2005, Americas Food and Drug Adm

15、inistration approved the therapy for depression that fails to respond to all conventional treatments, including drugs and psychotherapy. Not only does the treatment work, but its effects appear to be long lasting. A study led by Charles Conway of Saint Louis University in Missouri, and presented to

16、a recent meeting of the American Psychiatric Association, has found that 70% of patients who are better after one year stay better after two years as well.The technique builds on a procedure called deep-brain stimulation, in which electrodes are implanted deep into the white matter of patients brain

17、s and used to “reboot” faulty neural circuitry. Such an operation is a big undertaking, requiring a full day of surgery and carrying a risk of the patient suffering a stroke. Only a small number of people have been treated this way. In contrast, the device that stimulates the vagus nerve can be impl

18、anted in 45 minutes without a stay in hospital. The trouble is that vagus-nerve stimulation can take a long time to produce its full beneficial effect. According to Dr Conway, scans taken using a technique called positron-emission tomography show significant changes in brain activity starting three

19、months after treatment begins. The changes are similar to the improvements seen in patients who undergo other forms of antidepression treatment. The brain continues to change over the following 21 months. Dr Conway says that patients should be told that the antidepressant effects could be slow in co

20、ming. However, Richard Selway of Kings College Hospital, London, found that his patients moods improved just weeks after the implant. Although brain scans are useful in determining the longevity of the treatment, Mr Selway notes that visible changes in the brain do not necessarily correlate perfectl

21、y with changes in mood. Nobody knows why stimulating the vagus nerve improves the mood of depressed patients, but Mr Selway has a theory. He believes that the electrical stimulation causes a region in the brain stem called the locus caeruleus (Latin, ironically, for “blue place”) to flood the brain

22、with norepinephrine, a neurotransmitter implicated in alertness, concentration and motivationthat is, the mood states missing in depressed patients. Whatever the mechanism, for the depressed a therapy that is relatively safe and long lasting is rare cause for cheer.The shape of things to comeHow tom

23、orrows nuclear power stations will differ from todaysTHE agency in charge of promoting nuclear power in America describes a new generation of reactors that will be “highly economical” with “enhanced safety”, that “minimise wastes” and will prove “proliferation resistant”. No doubt they will bake a m

24、ean apple pie, too. Unfortunately, in the world of nuclear energy, fine words are not enough. America got away lightly with its nuclear accident. When the Three Mile Island plant in Pennsylvania overheated in 1979 very little radiation leaked, and there were no injuries. Europe was not so lucky. The

25、 accident at Chernobyl in Ukraine in 1986 killed dozens immediately and has affected (sometimes fatally) the health of tens of thousands at the least. Even discounting the association of nuclear power with nuclear weaponry, people have good reason to be suspicious of claims that reactors are safe. Y

26、et political interest in nuclear power is reviving across the world, thanks in part to concerns about global warming and energy security. Already, some 441 commercial reactors operate in 31 countries and provide 17% of the planets electricity, according to Americas Department of Energy. Until recent

27、ly, the talk was of how to retire these reactors gracefully. Now it is of how to extend their lives. In addition, another 32 reactors are being built, mostly in India, China and their neighbours. These new power stations belong to what has been called the third generation of reactors, designs that h

28、ave been informed by experience and that are considered by their creators to be advanced. But will these new stations really be safer than their predecessors? Clearly, modern designs need to be less accident prone. The most important feature of a safe design is that it “fails safe”. For a reactor, t

29、his means that if its control systems stop working it shuts down automatically, safely dissipates the heat produced by the reactions in its core, and stops both the fuel and the radioactive waste produced by nuclear reactions from escaping by keeping them within some sort of containment vessel. Reac

30、tors that follow such rules are called “passive”. Most modern designs are passive to some extent and some newer ones are truly so. However, some of the genuinely passive reactors are also likely to be more expensive to run.Nuclear energy is produced by atomic fission. A large atom (usually uranium o

31、r plutonium) breaks into two smaller ones, releasing energy and neutrons. The neutrons then trigger further break-ups. And so on. If this “chain reaction” can be controlled, the energy released can be used to boil water, produce steam and drive a turbine that generates electricity. If it runs away,

32、the result is a meltdown and an accident (or, in extreme circumstances, a nuclear explosionthough circumstances are never that extreme in a reactor because the fuel is less fissile than the material in a bomb). In many new designs the neutrons, and thus the chain reaction, are kept under control by

33、passing them through water to slow them down. (Slow neutrons trigger more break ups than fast ones.) This water is exposed to a pressure of about 150 atmospheresa pressure that means it remains liquid even at high temperatures. When nuclear reactions warm the water, its density drops, and the neutro

34、ns passing through it are no longer slowed enough to trigger further reactions. That negative feedback stabilises the reaction rate.Can business be cool?Why a growing number of firms are taking global warming seriouslyRUPERT MURDOCH is no green activist. But in Pebble Beach later this summer, the an

35、nual gathering of executives of Mr Murdochs News Corporationwhich last year led to a dramatic shift in the media conglomerates attitude to the internetwill be addressed by several leading environmentalists, including a vice-president turned climatechange movie star. Last month BSkyB, a British satel

36、lite-television company chaired by Mr Murdoch and run by his son, James, declared itself “carbon-neutral”, having taken various steps to cut or offset its discharges of carbon into the atmosphere.The army of corporate greens is growing fast. Late last year HSBC became the first big bank to announce

37、that it was carbon-neutral, joining other financial institutions, including Swiss Re, a reinsurer, and Goldman Sachs, an investment bank, in waging war on climate-warming gases (of which carbon dioxide is the main culprit). Last year General Electric (GE), an industrial powerhouse, launched its “Eco

38、magination” strategy, aiming to cut its output of greenhouse gases and to invest heavily in clean (ie, carbon-free) technologies. In October Wal-Mart announced a series of environmental schemes, including doubling the fuel-efficiency of its fleet of vehicles within a decade. Tesco and Sainsbury, two

39、 of Britains biggest retailers, are competing fiercely to be the greenest. And on June 7th some leading British bosses lobbied Tony Blair for a more ambitious policy on climate change, even if that involves harsher regulation.The greening of business is by no means universal, however. Money from Exx

40、on Mobil, Ford and General Motors helped pay for television advertisements aired recently in America by the Competitive Enterprise Institute, with the daft slogan “Carbon dioxide: they call it pollution; we call it life”. Besides, environmentalist critics say, some firms are engaged in superficial “

41、greenwash” to boost the image of essentially climate-hurting businesses. Take BP, the most prominent corporate advocate of action on climate change, with its “Beyond Petroleum” ad campaign, highprofile investments in green energy, and even a “carbon calculator” on its website that helps consumers me

42、asure their personal “carbon footprint”, or overall emissions of carbon. Yet, critics complain, BPs recent record profits are largely thanks to sales of huge amounts of carbon-packed oil and gas.On the other hand, some free-market thinkers see the support of firms for regulation of carbon as the lat

43、est attempt at “regulatory capture”, by those who stand to profit from new rules. Max Schulz of the Manhattan Institute, a conservative think tank, notes darkly that “Enron was into pushing the idea of climate change, because it was good for its business”.Others argue that climate change has no more

44、 place in corporate boardrooms than do discussions of other partisan political issues, such as Darfur or gay marriage. That criticism, at least, is surely wrong. Most of the corporate converts say they are acting not out of some vague sense of social responsibility, or even personal angst, but becau

45、se climate change creates real business risks and opportunitiesfrom regulatory compliance to insuring clients on flood plains. And although these concerns vary hugely from one company to the next, few firms can be sure of remaining unaffected.Testing timesResearchers are working on ways to reduce th

46、e need for animal experiments, but new laws mayincrease the number of experiments neededIN AN ideal world, people would not perform experiments on animals. For the people, they are expensive. For the animals, they are stressful and often painful.That ideal world, sadly, is still some way away. Peopl

47、e need new drugs and vaccines. They want protection from the toxicity of chemicals. The search for basic scientific answers goes on. Indeed, the European Commission is forging ahead with proposals that will increase the number of animal experiments carried out in the European Union, by requiring tox

48、icity tests on every chemical approved for use within the unions borders in the past 25 years.Already, the commission has identified 140,000 chemicals that have not yet been tested. It wants 30,000 of these to be examined right away, and plans to spend between 4 billion-8 billion ($5 billion-10 bill

49、ion) doing so. The number of animals used for toxicity testing in Europe will thus, experts reckon, quintuple from just over 1m a year to about 5m, unless they are saved by some dramatic advances in non-animal testing technology. At the moment, roughly 10% of European animal tests are for general to

50、xicity, 35% for basic research, 45% for drugs and vaccines, and the remaining 10% a variety of uses such as diagnosing diseases.Animal experimentation will therefore be around for some time yet. But the hunt for substitutes continues, and last weekend the Middle European Society for Alternative Meth

51、ods to Animal Testing met in Linz, Austria, to review progress.A good place to start finding alternatives for toxicity tests is the liverthe organ responsible for breaking toxic chemicals down into safer molecules that can then be excreted. Two firms, one large and one small, told the meeting how th

52、ey were using human liver cells removed incidentally during surgery to test various substances for long-term toxic effects.PrimeCyte, the small firm, grows its cells in cultures over a few weeks and doses them regularly with the substance under investigation. The characteristics of the cells are car

53、efully monitored, to look for changes in their microanatomy.Pfizer, the big firm, also doses its cultures regularly, but rather than studying individual cells in detail, it counts cell numbers. If the number of cells in a culture changes after a sample is added, that suggests the chemical in questio

54、n is bad for the liver.In principle, these techniques could be applied to any chemical. In practice, drugs (and, in the case of PrimeCyte, food supplements) are top of the list. But that might change if the commission has its way: those 140,000 screenings look like a lucrative market, although nobod

55、y knows whether the new tests will be ready for use by 2009, when the commission proposes that testing should start.Other tissues, too, can be tested independently of animals. Epithelix, a small firm in Geneva, has developed an artificial version of the lining of the lungs. According to Huang Song,

56、one of Epithelixs researchers, the firms cultured cells have similar microanatomy to those found in natural lung linings, and respond in the same way to various chemical messengers. Dr Huang says that they could be used in long-term toxicity tests of airborne chemicals and could also help identify t

57、reatments for lung diseases.The immune system can be mimicked and tested, too. ProBioGen, a company based in Berlin, is developing an artificial human lymph node which, it reckons, could have prevented the near-disastrous consequences of a drug trial held in Britain three months ago, in which (despi

58、te the drug having passed animal tests) six men suffered multiple organ failure and nearly died. The drug the men were given made their immune systems hyperactive. Such a response would, the firms scientists reckon, have been identified by their lymph node, which is made from cells that provoke the

59、immune system into a response. ProBioGens lymph node could thus work better than animal testing.Another way of cutting the number of animal experiments would be to change the way that vaccines are tested, according to Coenraad Hendriksen of the Netherlands Vaccine Institute. At the moment, all batches of vaccine are subject to the same battery of tests. Dr Hendriksen argues that this is over-rigorous. When new vaccine cultures are made, belt-and-braces te