VOA Special English 慢速英语听力材料

SCIENCE IN THE NEWS - January 8, 2002: Top stories of 2001
By Nancy Steinbach

VOICE ONE:

This is Bob Doughty.

VOICE TWO:

And this is Doug Johnson with the Special English program SCIENCE IN THE NEWS. Today, we tell about some major science stories of the year two-thousand-one. We tell about stem cell research, anthrax bacteria and the disease AIDS.

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VOICE ONE:

Last year, President Bush approved limited federal government support of research on special human cells. The research involves stem cells taken from fertilized human eggs called embryos.

Scientists believe stem cells may be highly useful in the treatment and possible cure of many diseases. The most useful are stem cells from embryos. They are able to develop into all the kinds of tissues of the body.

Embryonic stem cells are taken from embryos created in laboratories to help women become pregnant. Scientists use embryonic stem cells from embryos that are four or five days old.

During those first days, the cells in the embryo divide quickly. For a short period of time, each of the embryo's cells is able to become any one of more than two-hundred different kinds of cells in the body.

The great value of embryonic stem cells appears to be their ability to reproduce in large numbers in the laboratory before they become specialized cells. Researchers believe that embryonic stem cells may be used to help diseased organs develop healthy cells again.

They hope these stem cells can be used to treat diseases of the brain, heart, liver, pancreas and kidneys. These include diabetes, Parkinson's disease and Alzheimer's disease.

VOICE TWO:

However, the Bush Administration has only permitted research on about sixty groups of existing stem cells. Medical researchers have noted that these groups of stem cells are not useful for treating disease.

Also, treatments developed from existing stem cells might be rejected by the bodies of possible patients. This is because the genetic material is different.

Some scientists say the best way to make stem cells for treatment is to grow them from embryos that are exact copies of patients.

Late last year, scientists working for the company Advanced Cell Technology announced that they had made the first genetic copies of human embryos. The process of making genetic copies is called cloning.

Cloning involves the creation of an embryo from a single adult cell. Genetic material from the adult cell is joined with an egg cell whose genetic material has been removed. Scientists have used cloning to create animals.

Scientists from Advanced Cell Technology performed the experiments in an effort to create cloned human embryonic stem cells. However, the experiments did not produce stem cells because the embryos did not live long enough.

Company officials said the research on human embryos is designed only to produce embryonic stem cells to treat disease. They have strongly stated that the company has no interest in cloning human beings.

VOICE ONE:

American lawmakers have been preparing legislation that could ban or limit cloning. President Bush said he strongly opposes human cloning. He said it is wrong to use embryos for cloning. The Catholic Church opposes all kinds of stem cell research.

Many other religious groups also oppose all embryonic stem cell research. They consider it the same as taking a human life. Other religious groups accept the research with several restrictions because it may lead to cures for some diseases.

Experts say the debate about embryonic stem cell research is complex and will continue for some time.

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VOICE TWO:

Another major scientific story of Two-Thousand-One involved the disease anthrax. The deadly bacterium that causes the disease was found in letters mailed within the United States.

These letters were sent to several places, including major news organizations and congressional offices. This led to the closing of several government buildings and mail centers. Federal investigators say the anthrax was sent through the mail in an organized act of biological terrorism.

Letter to Senator Tom Daschle
Several people died as a result of breathing the anthrax bacteria into their lungs. Many other people are still taking medicines to protect against the disease if anthrax was found in buildings where they work.

Most recently, federal health officials have offered anthrax vaccine and more medicine to thousands of affected people. The fear is that the anthrax bacteria may still be present in their lungs even after taking antibiotic medicines for sixty days. The vaccine treatment is designed to prevent the disease. It is considered experimental because it has not been approved for use by people who already have breathed the anthrax bacteria.

VOICE ONE:

These incidents have spread fear and confusion across the country. They are also leading scientists to learn more about anthrax.Until the recent attacks, American scientists believed that particles of anthrax bacteria settled on a surface and did not move about in the air again.

But results from tests inside some affected buildings found that a number of particles entered the air again when investigators re-entered the buildings. And a test of mail-handling equipment found that even a machine that was partly cleaned still released anthrax into the air.

Officials from the Centers for Disease Control want to test different drugs for the disease. Other agencies are planning still more investigations. They want to learn how many particles it takes to infect a person with anthrax. They want to learn what health conditions make a person more likely than others to develop the disease.

They also want to know what drugs are the most effective treatments. And they want to know what would happen if the bacteria were released in an area where there are many people instead of through the mail.

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VOICE TWO:

Another major science story of last year was the continued struggle against the H-I-V virus and the disease it causes, AIDS. The United Nations says about forty-million people are living with H-I-V and AIDS around the world. That is an increase of about four-million from the year before. Officials say about three-million people died from the disease last year.

African countries have been most seriously affected. About seventy percent of all people infected with the disease live in Africa. More than three-million people in Africa were infected last year. Were it not for AIDS, life expectancy among Africans would be about sixty-two years instead of forty-seven.

AIDS victims in Burundi
The United Nations recently reported that AIDS is now spreading fastest in eastern Europe, especially Ukraine. The number of infections in Russia also has greatly increased. AIDS rates also have risen in Asia and the Middle East. An increase in dangerous sexual activities is leading to higher infection rates in some industrial countries.

However, some nations have reduced their number of AIDS cases. For example, Thailand, Brazil and Uganda have led successful treatment and prevention campaigns. These efforts also have reduced the number of babies born with the virus.

VOICE ONE:

The U-N General Assembly held it first conference about AIDS last year. More than three-thousand government leaders, health experts, activists and patients took part. At the meeting, the U-N established an international program to finance treatment and prevention efforts. Countries have promised about two-thousand-million dollars so far. Secretary-General Kofi Annan says the program needs at least seven-thousand-million dollars.

Some of the world's largest drug companies have sharply reduced the prices of powerful AIDS drugs for developing countries. But AIDS experts say this will have a limited effect until other problems are solved. For example, may Africans are not tested for the disease.

Many African countries do not have the necessary medical equipment to carry out needed blood tests. And few doctors know how to give AIDS drugs and supervise their use. But other experts say enough medical centers do exist to support AIDS drug programs in Africa. They say these problems can be solved.

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VOICE TWO:

This SCIENCE IN THE NEWS program was written by Cynthia Kirk, Mario Ritter and Nancy Steinbach. It was produced by Caty Weaver. This is Doug Johnson.

VOICE ONE:

And this is Bob Doughty. Join us again next week for more news about science in Special English on the Voice of America.