VOA慢速英语 2007 1030b（在线收听）

VOICE ONE:

This is SCIENCE IN THE NEWS in VOA Special English.  I'm Bob Doughty.

VOICE TWO:

 
Researchers at Ohio State University studied exercise-induced asthma among top athletes at the school. Ohio State football players practice earlier this year.
And I'm Faith Lapidus.  On our program this week, we will tell about the winners of the Nobel Prize in medicine.  We will tell about a health problem resulting from physical exercise.  We also report on depression in young people and genetic studies of an ancient animal. 

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The two thousand seven Nobel Prize in medicine will go to three men who found a way to learn about the duties of individual genes.  They discovered how to inactivate, or knock out, single genes in laboratory animals.  The result is known as "knockout mice." 

 
Mario Capecchi holds a laboratory mouse
The Karolinska Institute named the winners earlier this month.  They are Martin Evans of Britain and two Americans, Mario Capecchi and .  They will receive what is officially called the Nobel Prize in Physiology or Medicine at a ceremony in Sweden on December tenth.  They also will share about one million five hundred thousand dollars in prize money. 

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In the nineteen eighties, Mario Capecchi and Oliver Smithies both studied cells in mice.  They wanted to find how to cause changes in individual genes.  But the kinds of cells they independently studied could not be used to create gene-targeted animals.

Martin Evans had the solution.  He worked with embryonic stem cells to produce mice that carried new genetic material.

 
Oliver Smithies
The research greatly expanded knowledge about embryonic development, aging and disease.  It also led to a new technology -- gene targeting.  This has already produced five hundred mouse models of human conditions.  Knockout mice are used for general research and for the development of new treatments. 

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VOICE ONE:

A new study shows the breathing disorder asthma is common among students who take part in college athletic programs.  Researchers studied American college athletes for signs of breathing problems.  Athletes need skill and strength to compete in a sport.  Yet test results suggested that more than one-third of those studied had a condition called exercise-induced asthma.  In other words, physical exercise caused their asthma.  This was true even among college athletes who had no history of the disorder. 

Exercise-induced asthma happens when exercise restricts the flow of air to the lungs.  The narrowing and closing of the airway usually begins just after heavy exercise.  One sign of exercise-induced asthma is increased amounts of sticky fluid, or mucus, in the airway.  Other signs include difficulty breathing and tightness in the chest.  Two dangers of the condition are reduced athletic performance and serious breathing problems. 

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Researchers at Ohio State University Medical Center organized the study.  They examined one hundred seven student athletes at the university.  The athletes were from Ohio State’s top sports teams. 

Forty-two of those tested showed signs of exercise-induced asthma.  Thirty-six members of that group had no earlier history of the breathing disorder.  The researchers say the sex of the athlete and the breathing demands of the sport did not affect the rate of exercise-induced asthma.

Jonathan Parsons was the lead writer of the report.  He says college students were tested because many of the reported severe cases of asthma after exercise have involved athletes twenty years of age or younger. 

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Doctor Parsons says the findings suggest that many athletes do not know they have exercise-induced asthma.  He says many parents, trainers and even athletes accept signs of the disorder as normal effects of physical activity. 

Other athletes in the study showed signs of breathing problems after exercise.  But the researchers say they were not common cases of exercise-induced asthma. 

Doctor Parsons says the signs of exercise-induced asthma are not always clear.  He says linking the condition to all breathing problems tied to exercise will result in wrong findings.  This, he says, is why testing is so important.

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VOICE TWO:

You are listening to the VOA Special English program SCIENCE IN THE NEWS.  With Bob Doughty, I'm Faith Lapidus in Washington. 

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Depression can cause long periods of sadness and hopelessness, feelings of low self-worth, even physical pain.  It is the leading cause of suicide.  The World Health Organization says more than one hundred twenty million people worldwide suffer from depression.  But many people may not know it can start at a young age. 

Recently, researchers in the United States reported on a study of more than three hundred young people.  All the patients were twelve to seventeen years of age.  They suffered from major depression disorder, the most common form of the disease.

The researchers divided them into three groups.  One group received the antidepressant drug Prozac.  Another received cognitive behavioral therapy.  This kind of treatment teaches patients to recognize and deal with the thoughts that can result from depression.  The third group received both cognitive behavioral therapy and the antidepressant drug.

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The study found that the combination of treatments was most effective.  At twelve weeks, the researchers found reduced levels of depression in all three groups.  But they say the group receiving the combined treatments had the greatest reduction.  This continued through the end of the nine-month study.

The study did not include an untreated control group.  So there is no way to know for sure if it was the treatment that eased the depression.

The findings by Duke University researchers appear in the Archives of General Psychiatry.  America's National Institute of Mental Health paid for the study. 

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VOICE TWO:

An international team of scientists has recovered genetic information from hairs of ancient wooly mammoths.  The scientists say the genetic material will provide valuable information about an animal alive today -- the elephant.  They say it may also help in the study of mammoths and other ancient animals.   

Mammoths lived on Earth thirty thousand to sixty thousand years ago.  They are ancestors of modern African and Indian elephants. 

Most of the hairs in the study came from a frozen mammoth.  Its remains were found in the Siberia area of Russia in seventeen ninety-nine.  For the past two centuries, the hair remains were stored at room temperature at the Zoological Museum in Saint Petersburg.

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Stephan Schuster was part of the team that made a genetic map from the mammoth hair remains.  He works at Pennsylvania State University in the United States. 

Professor Schuster says no team member thought it would be possible to get usable genetic material from the hair remains.  He says the scientists had thought that removing the hairs from a cold climate would have destroyed every gene.  Yet the scientists found genetic information in even the smallest piece of hair.

Professor Schuster notes that scientists are able to collect genes from the bones of dinosaurs.  That is how they know about the age and development of the ancient creatures.  But he adds that genetic studies of dinosaur bones are costly and difficult.  The bones have very small holes.  It is difficult to separate the genes scientists want to study from bacteria, plant and other material. 

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Professor Schuster says genetic testing of hair is simple and does not cost much.  He says his team found the bacteria on the outer end of the hair remains.  The scientists were able to the outer end whiter while the other end remained undamaged.  After removing the bacteria, the scientists were able to observe very pure genetic material from the mammoth. 

Professor Schuster says this kind of test can be performed on something as small as a single hair.  And he says the scientists found usable genes along the complete hair, not just the hair root closest to the skin.

Professor Schuster says the genetic map will tell scientists a lot about the development of Indian and African elephants.  He says it may provide clues about how long it took before they separated and their last common ancestor.  A report describing the study was published in Science magazine.

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VOICE ONE:

This SCIENCE IN THE NEWS was written by Lawan Davis, SooJee Han and Caty Weaver.  Brianna Blake was our producer.  I'm Bob Doughty.

VOICE TWO:

And I'm Faith Lapidus.