VOA慢速英语20060919b

（单词翻译）

SCIENCE IN THE NEWS - Study Finds Older Fathers Are More Likely to Have Autistic ChildrenBy Caty Weaver¹ and Jerilyn Watson

Broadcast: Tuesday, September 19, 2006

VOICE ONE:

This is SCIENCE IN THE NEWS in VOA Special English. I'm Bob Doughty².

VOICE TWO:

And I'm Faith Lapidus. This week -- a report on the link found between older fathers and the risk of autism in children ...

VOICE ONE:

And the story of how scientists genetically⁵ engineered normal cells to fight cancer.

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VOICE TWO:

Findings from a new study suggest a link between a man's age and the chances that his children will develop autism. Researchers found that men age forty and older had autistic children almost six times as often as fathers under the age of thirty.

Men in their thirties were about one and one-half times more likely to father an autistic child as dads in their twenties and teen years.

The study found no link between autism and older mothers.

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The study involved children born in Israel in the nineteen eighties. The findings come from the records of medical examinations for seventeen-year-olds for required military service.

The records for more than one hundred thirty thousand teenagers included the ages of both their father and their mother.

Within this group, the records showed that there were one hundred ten cases of autism spectrum⁶ disorder⁷. Autism spectrum disorder is the name for autism and related conditions. The rate of cases was eight out of ten thousand people.

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The scientists discuss several possible genetic⁴ causes for the age effect they documented in fathers. They say people should keep in mind, however, that social environments influence the age when a man fathers children. It differs across societies and can change as conditions change over time.

Abraham Reichenberg of Mount Sinai School of Medicine in New York and the Institute of Psychiatry⁸ at King's College, London, led the study. The findings appeared earlier this month in the Archives of General Psychiatry, published by the American Medical Association.

In the last twenty years, more and more children have been identified as autistic. The researchers say the increase is partly the result of more knowledge about autism and changes in how doctors identify it. But they note that it could also represent an increase in this disorder.

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Ryan Taylor was diagnosed with autism in 2004; he is shown with his father, Craig, at their home in Connecticut

What exactly is autism? This is not an easy question even for experts to answer. A recent press release from the National Institute of Mental Health, in the United States, described it as a mental disorder. Some people, though, object to such a description. Other materials from the institute have called it a brain disorder.

Autism appears in early childhood. Autistic children experience delays in the development of social and communication skills. These social and language problems usually appear around three years of age.

The disorder is found more often in boys than girls, but girls often have more severe effects.

Autistic children often appear emotionally withdrawn⁹ from other people. They may also show limited interests and repeat the same actions over and over again, like rocking back and forth¹⁰.

Scientists are trying to better understand autism as they search for its causes and for effective treatments.

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On September seventh, the National Institute of Mental Health announced the start of three major studies of autism. These are being done at its research program at the National Institutes of Health in Bethesda, Maryland.

One study aims to define differences in autistic children with different developmental histories. Another study will measure the effectiveness of an antibiotic¹¹ medicine as a treatment for one kind of autism. And the third study will try to find out if chelation [pronounced key-LAY-shun] treatment is effective against autism.

Chelation removes heavy metals from the blood. This treatment is used for children with lead poisoning. But many parents seek it for autistic children to try to remove mercury from their blood. They believe that many cases of autism were caused by vaccines¹³ that contained thimerosal, a mercury-based preservative¹⁴. That theory is debated.

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Researchers will carry out a controlled study to test the effectiveness and safety of chelation for children with autism spectrum disorders¹⁵. Institute officials note that chelation does not target mercury alone. It can also remove minerals that the body needs, such as calcium¹⁶, iron and zinc¹⁷.

Federal officials say most vaccines for children age six and younger now contain either no thimerosal or very small amounts. This has been true since two thousand one, they say, but an exception is inactivated¹⁸ flu vaccine¹². Currently there is a limited supply of thimerosal-free vaccine against influenza¹⁹, for use in children six months to twenty-three months old.

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The National Institute of Mental Health says autism may represent several different diseases. Autism presents itself in different ways and is part of a larger group of disorders. These are often called autism spectrum disorders. They also include Asperger's syndrome²⁰ and pervasive²¹ developmental disorder.

Institute officials say autism spectrum disorders are currently reported to affect as many as six out of every one thousand children.

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VOICE ONE:

You are listening to SCIENCE IN THE NEWS in VOA Special English.

Researchers at the National Institutes of Health have successfully used genetic engineering to treat the deadliest form of skin cancer.

The journal Science reported the results of a study of patients with advanced melanoma. Steven Rosenberg led a team at the National Cancer Institute. The study involved seventeen patients. The disease had spread through their bodies. Other treatments had failed.

The researchers changed the genetic structure of the patients' own white blood cells to get them to recognize and attack cancer cells. Two patients are now free of melanoma. They are alive a year and a half after the experimental treatment began. All of the other patients have since died.

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Using a person's own white blood cells to treat melanoma is not a new idea. But what doctors have done until now is to look for the most aggressive cancer-killing cells that a patient already has. They grow more of them in the laboratory and return them to the patient's body.

But this treatment is said to work only for melanoma. And it can only be used for patients who already have specialized²² cells that can recognize cancers.

Not very many patients with advanced melanoma produce enough cancer-fighting T-cells naturally in their blood. So Doctor Rosenberg and his team decided²³ to make cancer-fighting cells in their laboratory.

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To do this, the scientists removed normal T-cells from the blood of the patients. Then they infected the cells with a retrovirus.

The retrovirus carried special genes²⁴. These genes produce T-cell receptors. Once inside the body, the receptors are able to seek out and work against the melanoma cells.

The team also has found T-cell receptors that can find other common cancers. The head of the National Institutes of Health, Elias Zerhouni, said the results represent the first time gene³ therapy has been used successfully to treat cancer. Scientists say they hope this kind of gene therapy could also be used for breast and lung cancer, among others.

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The study showed that engineered cells can stay in the body and, in some cases, shrink large cancers.

Other scientists praised the work of Doctor Rosenberg and his team. But they also said the rate of survival with this method must be improved. Studies continue toward that goal, including the use of total-body radiation to improve the effectiveness.

In the late nineteen eighties, many scientists believed genetic engineering might help fight a number of cancers. Laboratory studies appeared to offer hope. But most human tests were unsuccessful.

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VOICE ONE:

SCIENCE IN THE NEWS was written by Caty Weaver and Jerilyn Watson and produced by Brianna Blake. I'm Bob Doughty.

VOICE TWO:

And I'm Faith Lapidus. Transcripts²⁵ and audio files of our programs can be found at www.unsv.com. Listen again next week for more news about science in Special English on the Voice of America.