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自考英语二阅读辅导8
发布日期:2012/2/22 来源:广东自考网 阅读: 【字体:

快乐扑克三开奖结果 www.fw7g8.cn Sacrificed to Science?

  Professor Colin Blakemore works at Oxford University Medical School doing research into eye problems and believes that animal research has given humans many benefits:The use of animals has been central to the development of anaesthetics, vaccines and treatments for diabetes, cancer, developmental disorders…most of the major medical advances have been based on a background of animal research and development.

  There are those who think the tests are simply unnecessary. The International Association Against Painful Experiments on Animals is an organization that promotes the use of alternative methods of research which do not make animals suffer. Their spokesman Colin Smith says:

  Animal research is irrelevant to our health and it can often produce misleading results. People and animals are different in their reactions to drugs and in the way their bodies work. We only have to look at some of the medical mistakes to see this is so.

  But Professor Blackmore stresses:It would be completely irresponsible and unethical to use drugs on people that had not been thoroughly tested on animals. The famous example of thalidomide is a case for more animal testing, not less.

  The birth defects that the drug produced were a result of inadequate testing. If thalidomide were invented today, it would never be released for human use because new tests on pregnant animals would reveal the dangers.

  Another organization that is developing other methods of research is FRAME. This is the Fund for the Replacement of Animals in Medical Experiments. It recognises that many experiments still have to be done on animals and is aiming for Reduction, Refinement and Replacement of animals in experiments. In 1981, it established a research programme to improve and expand non-animal testing. Increasingly, new technology is making it easier for us to find alternative methods of testing.

  Computer models can be used to simulate the way that cells work and to try to predict the toxicity of chemicals. Data from previous animal experiments is used to develop a computer model which will predict what will happen if you add a chemical with an unknown biological effect to a substance. The eventual aim of computer modeling is to reduce the number of animals used in experiments.

  The Lethal Dose 50 test (LD50) may also be replaced. In the original test, all the animals in a test group are given a substance until half of them die. The test indicates toxicity. A method using a fixed amount, which gives the same eventual information but uses fewer animals and does not require that they die, may replace the LD50. Many other new techniques are now available that enable more research to be done in the test tube to see if chemicals produce harmful biological effects.

  The number of animals used in laboratory tests has declined over the last 20 years. This is partly due to alternatives and partly to the fact that experiments are better disigned so fewer need to be used - healthier animals provide better experimental results. For example, it used to take 36 monkeys to test a sample of polio vaccine, now it takes only 22. Also, lack of money has reduced the number of animals used - they are expensive to buy and expensive to keep.

  Birmingham University now has Britain's first department of Biomedical Ethics. Professor David Morton of the department is involved in animal research and is concerned with reducing animal suffering as much as possible. Animals spend 95% of their time in their cages and refinement also means making their lives better when not undergoing tests. This includes keeping them in more suitable cages, allowing social animals like dogs to live together and trying to reduce the boredom that these animals can experience.

  In Professor Morton's laboratory, rabbits live together in large runs, filled with deep litter and boxes that they can hide in. The researchers have also refined some experiments. In the US, one experiment in nerve regeneration involves cutting a big nerve in a rat's leg, leaving its leg paralysed. In Morton's lab, the researcher cuts a small nerve in the foot. He can see if it can regrow and the rat can still run around its cage.

  Even with these new developments in research, only a tiny proportion of all tests are done without using animals at some stage. The use of animals in experiments cannot stop immediately if medical research is to continue and consumer products are to be properly tested, and Professor Blakemore believes that sometimes there are no alternatives:

  Wherever possible, for both ethical and scientific reasons, we do not use animals. But cells live in animals and we can only really see how they behave when they are inside animals. We cannot possibly reproduce in a test tube or a computer model all the complex reactions of the body to a drug or a disease. When it comes to research into heart disease and its effects on the body, or diseases of the brain for example, we do not have adequate substitutes for the use of animals.

  As research techniques become more advanced, the number of animals used in experiments may decrease, but stopping testing on animals altogether is a long way away.

  

为科学而献身

  科林布莱克默教授在牛津大学医学院工作,从事眼睛疾病的研究。他相信对动物的研究已使人类获益匪浅。

  使用动物对于麻醉学和疫苗的发展,对糖尿病、癌症和紊乱的治疗等极其重要。多数重要的医学都是以动物研究和开发的背景为基础的。

  有些人认为这些实验毫无必要。国际反动物痉实验协会是一个提倡使用不使动物痉的替代方法的组织。他们的发言人科林史密斯说:对动物的研究和我们的健康无关,它常常产生令人误入歧途的结果。人和动物对药物的反应及他们身体运作的方式都不同。我们只要看一看医疗失误就会明白。但布莱克默说:没有认真在动物身上实验的药物大人身上使用,是完全不负责和不合道理的。萨力多胺就是一个著名的例子。它证明需要更多的动物实验而不是更少的动物实验。这种药物引起的先天性畸形是缺乏实验的结果。如果萨力多胺是现在发明的,它就不会被批准为人类使用,因为在有孕的动物身上实验会提示其危险。

  另一个开发其他研究办法的组织是FRAME,"替代动物医学实验基金会"的简称。它认识到许多实验仍然不得不使用动物,该基金会旨在减少使用动物,改良使用动物,甚至替代动物。在1981年,它们设立了一个改进和扩大无动物实验的研究项目。渐渐地,新科技使我们更易于找到进行实验可供选择的办法。电脑模型可以用来模拟细胞的活动方式和预测化学制品的毒性。以前的动物数据用来开发一个电脑模型,它能预测如果一种物质中加入某种未知生物作用的化学药品会发生什么。电脑模型的最终目标是减少用于实验的动物数量。

  致死计量50实验(LD50)也可以被代替。在过去的实验中,实验群中所有的动物被喂给一种物质,直到其中一半死亡。这个实验表明其毒性。一种用固定的数量可以得到相同的结论,但是使用较少动物而且不使它们死亡的方法可能代替LD50。现在已有许多其他的技术,可使更多的研究工作在试管中进行,从而发现化学药品是否产生有害的生物作用。

  过去的20年里,实验室里实验中使用的动物数量减少;其部分原因是由于可供选择的方法多了,另外部分是由于实验设计得更好,因为使用更健康的动物能产生更好的实验结果,所以用的动物减少了。例如,过去常用36只猴子来实验脊髓质炎疫苗样本,现在只用22只。缺少资料已使所使用的动物数量减少了 ――购买和使用动物都很昂贵。

  伯明翰大学现在设有英国首家生物医学伦里学系。系里的大卫莫顿教授从事动物研究,并对尽可能地减少动物的痉很关心。动物们在笼子里度过了他们 95%的时间,改良也意味阒不进行实验时使它和得更好些。这包括在更舒适的笼子里喂养它们,允许像狗那类喜欢合群的动物生活在一起,尽量减少这些动物可能经历的烦恼。

  在莫顿教授的实验室里,大批兔子一起生活,到处是厚厚的干草和箱子供它们躲藏。者们还改进了一些实验。在美国,神经再生方面的发切断鼠脚里的一条小神经。他可以看到神经是否可以再生,而老鼠仍在笼子里四处跑。

  尽管这些研究有了新成果,所有的裕只有极少数在某一阶段不使用动物。

  如果医学实验研究还要继续,消费性门牌号学要严格地进行检验,这样在实验中使用动物就不会立即停止。布莱克莫教授相信有时是无可选择的。

  无论在何处,有可能的话,基于伦理和科学的原因,我们不应使用动物做实验。但是细胞生活在动物体内,只有当细胞在动物体内时我们才能真正看清它们是如何活动的。我们不可能在试管中或电脑模型里复制出身体对疾病或芗的所有复杂反应。涉及到研究心脏病和它对身体的影响时,例如脑内疾病,我们没有代替使用动物的合适的替代物。

  随着研究技术变得更先进,实验中使用的动物数量可能会减少,但完全停止在动物身上实验还有很长的路要走。

 

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