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VOA慢速英语20061212b

时间:2006-12-26 16:00来源:互联网 提供网友:shimianmaifu   字体: [ ]
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VOICE ONE:

This is SCIENCE IN THE NEWS, in VOA Special English. I'm Steve Ember.

VOICE TWO:

And I'm Barbara Klein. This week -- the story of aspirin1.

(MUSIC)

VOICE ONE:

Our story begins with the willow2 tree. Since ancient times, people have known about its ability to reduce pain and high body temperature. More than two thousand years ago, the Greek doctor Hippocrates advised his patients to chew on the bark and leaves of the willow.

The tree contains a chemical called salicin. From salicin, researchers in the eighteen hundreds discovered how to make salicylic acid. And in eighteen ninety-seven, a chemist named Felix Hoffmann at Friedrich Bayer and Company in Germany created acetyl salicylic acid.

Later it became the active substance in a new medicine that Bayer called aspirin. The a came from acetyl. The spir came from the spirea plant, which also produces salicin. And the in? Well, that is a common way to end medicine names.


Aspirin

VOICE TWO:

In nineteen eighty-two, a British scientist shared the Nobel Prize in Medicine in part for discovering how aspirin works. Sir John Vane found that aspirin blocks the body from making natural substances called prostaglandins.

Prostaglandins have several effects on the body. Some cause pain and the expansion, or swelling4, of damaged tissue. Others protect the lining5 of the stomach and small intestine6.

Prostaglandins also make the heart, kidneys and blood vessels7 work well. But there is a problem. Aspirin works against all prostaglandins, good and bad.

(MUSIC)

VOICE ONE:

Scientists learned how aspirin interferes9 with an enzyme10. One form of this enzyme makes the prostaglandin that causes pain and swelling. Another form of the enzyme creates a protective effect. So aspirin can reduce pain and swelling in damaged tissues. But it can also harm the inside of the stomach and small intestine.

Today, aspirin competes with a lot of other medicines for headaches, muscle pain and fever. These include acetaminophen, the active substance in products like Tylenol.

But many people take aspirin to reduce the risk of a heart attack or stroke from blood clots11. Clots can block the flow of blood to the heart or brain and cause a heart attack or stroke. Scientists say aspirin prevents blood cells called platelets from sticking together to form clots.

A California doctor named Lawrence Craven first noted12 this effect more than fifty years ago. He observed unusual bleeding in children who chewed on an aspirin product to ease the pain after a common throat operation.

VOICE TWO:

Doctor Craven believed that the bleeding was because aspirin prevented blood from thickening. He thought that this effect might help prevent heart attacks caused by blood clots.

He examined the medical records of eight thousand aspirin users and found no heart attacks in this group. He invited other scientists to test his ideas. But it was years before large studies took place.

Charles Hennekens of Harvard Medical School led one of the studies. In nineteen eighty-three, he began to study more than twenty-two thousand healthy male doctors over forty years of age. Half took an aspirin every other day. The others took what they thought was aspirin. It was only a placebo13, an inactive substance.

Five years later, Doctor Hennekens reported that those who took aspirin reduced their risk of a heart attack. But they also had a higher risk of bleeding in the brain than the other doctors.

VOICE ONE:

More recently, a group of experts examined studies of aspirin at the request of federal health officials in the United States. The experts said people with an increased risk of a heart attack should take a low-strength aspirin every day.

People who are most likely to suffer a heart attack include men over forty and women over fifty. People who are overweight or smoke are also at greater risk. So are people with heart disease, diabetes14, high blood pressure or high cholesterol15.

VOICE TWO:

In two thousand five, scientists reported the results of a major study that confirmed that aspirin also helps women. But the results were surprising. The study found that aspirin did not reduce the risk of a first heart attack in women.

But women who took aspirin were seventeen percent less likely to have a stroke than women who took a placebo. And they were twenty-four percent less likely to have the most common form of stroke. The effects were greatest in women sixty-five years of age and older.

The results were the opposite of what doctors see in men.

The study lasted ten years. It involved forty thousand women age forty-five to eighty. The women who took aspirin were given one hundred milligrams every other day.

(MUSIC)

VOICE ONE:

Aspirin may help someone who is having a heart attack caused by a blockage16 in an artery17. Aspirin thins the blood, so it may be able to flow past the blockage. But heart experts say people should seek emergency help immediately. They say an aspirin is no substitute for treatment.

And some people should not take aspirin. These include people who take other blood thinners or have bleeding disorders18. Pregnant women are usually told to avoid aspirin. And children who take aspirin can suffer a disease called Reye's syndrome19.

Aspirin can also interfere8 with other medicines, although this is true of many drugs.

A well-known risk of aspirin is stomach bleeding. Acid in the drug can damage the tissue of the stomach or intestines20. Yet some studies have found that aspirin may help prevent cancers of the stomach, intestines and colon21.

VOICE TWO:

A recent study found that aspirin blocks the formation of blood vessels that feed the growth of cancer. Researchers at Newcastle University in England explored a biological process that makes blood vessels grow. The researchers studied how aspirin affects the cells found on the inner surface of blood vessels. They found that a small amount of aspirin suppressed the way the cells form tubes.

But lead researcher Helen Arthur says people with cancer should not take aspirin unless they are advised to do so by a doctor. She warns that large amounts of aspirin over a long period can cause severe stomach bleeding and death.

VOICE ONE:

Aspirin is one of a group of medicines known as NSAIDs [EN-sayds] -- non-steroidal anti-inflammatory drugs. Another example is ibuprofen.

Several studies have found that men who take NSAIDS have a decreased risk of prostate cancer. Researchers at the Mayo Clinic in Minnesota wanted to see how NSAIDS might affect prostates that are enlarged but not cancerous.

They followed the health of two thousand five hundred men for twelve years. One-third were taking NSAIDs daily when they entered the study.

The scientists recently announced that these drugs may delay or prevent the development of an enlarged prostate. They said the risk of an enlarged prostate was fifty percent lower in the NSAID users than the other men. And the risk of bladder problems was thirty-five percent lower.

The prostate gland3 is part of the male reproductive system and is just below the bladder. Growth of the prostate is common as men get older. It can mean repeated visits to the bathroom and other effects on a man's quality of life.

But the scientists say that because of risks like stomach bleeding, they are not advising all men to take aspirin. If men are taking it already, they say, then the findings suggest another way it might help. The reasons are not clear, though, and the findings must be reproduced by other studies

Most of the men were taking aspirin. But the study found that other kinds of NSAIDs appeared to have the same effect. And the amount taken did not seem to make much difference either.

In any case, medical experts say people should not take aspirin for disease prevention without first talking to a doctor. There are risks, and researchers have reported that some people get little or no protection from aspirin. But medical research continues to give new life to one of the oldest and most widely used drugs in the world.

(MUSIC)

VOICE TWO:

SCIENCE IN THE NEWS was written by George Grow and produced by Brianna Blake. For more science news, and MP3 files and transcripts22 of our programs, go to www.unsv.com. I'm Barbara Klein.

VOICE ONE:

And I'm Steve Ember. We hope you can join us again next week for more news about science in Special English on the Voice of America.


点击收听单词发音收听单词发音  

1 aspirin 4yszpM     
n.阿司匹林
参考例句:
  • The aspirin seems to quiet the headache.阿司匹林似乎使头痛减轻了。
  • She went into a chemist's and bought some aspirin.她进了一家药店,买了些阿司匹林。
2 willow bMFz6     
n.柳树
参考例句:
  • The river was sparsely lined with willow trees.河边疏疏落落有几棵柳树。
  • The willow's shadow falls on the lake.垂柳的影子倒映在湖面上。
3 gland qeGzu     
n.腺体,(机)密封压盖,填料盖
参考例句:
  • This is a snake's poison gland.这就是蛇的毒腺。
  • Her mother has an underactive adrenal gland.她的母亲肾上腺机能不全。
4 swelling OUzzd     
n.肿胀
参考例句:
  • Use ice to reduce the swelling. 用冰敷消肿。
  • There is a marked swelling of the lymph nodes. 淋巴结处有明显的肿块。
5 lining kpgzTO     
n.衬里,衬料
参考例句:
  • The lining of my coat is torn.我的外套衬里破了。
  • Moss makes an attractive lining to wire baskets.用苔藓垫在铁丝篮里很漂亮。
6 intestine rbpzY     
adj.内部的;国内的;n.肠
参考例句:
  • This vitamin is absorbed through the walls of the small intestine.这种维生素通过小肠壁被吸收。
  • The service productivity is the function,including external efficiency,intestine efficiency and capacity efficiency.服务业的生产率是一个包含有外部效率、内部效率和能力效率的函数。
7 vessels fc9307c2593b522954eadb3ee6c57480     
n.血管( vessel的名词复数 );船;容器;(具有特殊品质或接受特殊品质的)人
参考例句:
  • The river is navigable by vessels of up to 90 tons. 90 吨以下的船只可以从这条河通过。 来自《简明英汉词典》
  • All modern vessels of any size are fitted with radar installations. 所有现代化船只都有雷达装置。 来自《现代汉英综合大词典》
8 interfere b5lx0     
v.(in)干涉,干预;(with)妨碍,打扰
参考例句:
  • If we interfere, it may do more harm than good.如果我们干预的话,可能弊多利少。
  • When others interfere in the affair,it always makes troubles. 别人一卷入这一事件,棘手的事情就来了。
9 interferes ab8163b252fe52454ada963fa857f890     
vi. 妨碍,冲突,干涉
参考例句:
  • The noise interferes with my work. 这噪音妨碍我的工作。
  • That interferes with my plan. 那干扰了我的计划。
10 enzyme cPozF     
n.酵素,酶
参考例句:
  • Above a certain temperature,the enzyme molecule will become unfolded.超过一定温度,酶分子将会展开。
  • An enzyme that dissolves the fibrin of blood clots.能溶解血凝块中的纤维的酶。
11 clots fc228b79d0fbd8618ecc4cda442af0dd     
n.凝块( clot的名词复数 );血块;蠢人;傻瓜v.凝固( clot的第三人称单数 )
参考例句:
  • When you cut yourself, blood clots and forms a scab. 你割破了,血会凝固、结痂。 来自《简明英汉词典》
  • Milk clots when it turns sour. 奶变酸就凝块。 来自《现代英汉综合大词典》
12 noted 5n4zXc     
adj.著名的,知名的
参考例句:
  • The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
  • Jim is noted for arriving late for work.吉姆上班迟到出了名。
13 placebo placebo     
n.安慰剂;宽慰话
参考例句:
  • The placebo has been found to work with a lot of different cases.人们已发现安慰剂能在很多不同的病例中发挥作用。
  • The placebo effect refers to all the observable behaviors caused by placebo.安慰剂效应是指由安慰剂所引起的可观察的行为。
14 diabetes uPnzu     
n.糖尿病
参考例句:
  • In case of diabetes, physicians advise against the use of sugar.对于糖尿病患者,医生告诫他们不要吃糖。
  • Diabetes is caused by a fault in the insulin production of the body.糖尿病是由体內胰岛素分泌失调引起的。
15 cholesterol qrzzV     
n.(U)胆固醇
参考例句:
  • There is cholesterol in the cell of body.人体细胞里有胆固醇。
  • They are determining the serum-protein and cholesterol levels.他们正在测定血清蛋白和胆固醇的浓度。
16 blockage XRxyc     
n.障碍物;封锁
参考例句:
  • The logical treatment is to remove this blockage.合理的治疗方法就是清除堵塞物。
  • If the blockage worked,they could retreat with dignity.如果封锁发生作用,他们可以体面地撤退。
17 artery 5ekyE     
n.干线,要道;动脉
参考例句:
  • We couldn't feel the changes in the blood pressure within the artery.我们无法感觉到动脉血管内血压的变化。
  • The aorta is the largest artery in the body.主动脉是人体中的最大动脉。
18 disorders 6e49dcafe3638183c823d3aa5b12b010     
n.混乱( disorder的名词复数 );凌乱;骚乱;(身心、机能)失调
参考例句:
  • Reports of anorexia and other eating disorders are on the increase. 据报告,厌食症和其他饮食方面的功能紊乱发生率正在不断增长。 来自《简明英汉词典》
  • The announcement led to violent civil disorders. 这项宣布引起剧烈的骚乱。 来自《简明英汉词典》
19 syndrome uqBwu     
n.综合病症;并存特性
参考例句:
  • The Institute says that an unidentified virus is to blame for the syndrome. 该研究所表示,引起这种综合症的是一种尚未确认的病毒。
  • Results indicated that 11 fetuses had Down syndrome. 结果表明有11个胎儿患有唐氏综合征。
20 intestines e809cc608db249eaf1b13d564503dbca     
n.肠( intestine的名词复数 )
参考例句:
  • Perhaps the most serious problems occur in the stomach and intestines. 最严重的问题或许出现在胃和肠里。 来自辞典例句
  • The traps of carnivorous plants function a little like the stomachs and small intestines of animals. 食肉植物的捕蝇器起着动物的胃和小肠的作用。 来自辞典例句
21 colon jqfzJ     
n.冒号,结肠,直肠
参考例句:
  • Here,too,the colon must be followed by a dash.这里也是一样,应当在冒号后加破折号。
  • The colon is the locus of a large concentration of bacteria.结肠是大浓度的细菌所在地。
22 transcripts 525c0b10bb61e5ddfdd47d7faa92db26     
n.抄本( transcript的名词复数 );转写本;文字本;副本
参考例句:
  • Like mRNA, both tRNA and rRNA are transcripts of chromosomal DNA. tRNA及rRNA同mRNA一样,都是染色体DNA的转录产物。 来自辞典例句
  • You can't take the transfer students'exam without your transcripts. 没有成绩证明书,你就不能参加转学考试。 来自辞典例句
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