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VOICE ONE:
This is Sarah Long.
VOICE TWO:
And this is Bob Doughty with Science in the News, a VOA Special English program about recent developments in science. Today, we tell about a new vaccine that may prevent a kind of cancer. We tell about a study that says older women can have healthy babies. And we tell about efforts to make silk by using genetic engineering.
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VOICE ONE:
American scientists have developed the first vaccine that appears to prevent cancer of the cervix, the entrance to the uterus. The vaccine works by protecting women from developing a virus infection that causes many cases of cervical cancer.
A new study shows that this experimental vaccine can protect against a form of human papilloma virus, or H-P-V. This virus is called H-P-V Sixteen. The researchers reported that the vaccine proved one-hundred-percent effective against H-P-V Sixteen. H-P-V Sixteen causes about half of all cervical cancers. The H-P-V virus is spread during sex.
VOICE TWO:
The study results appeared in the New England Journal of Medicine. Scientists from Merck Research Laboratories of West Point, Pennsylvania developed the vaccine. They carried out the study with researchers from sixteen universities. More testing will be done to confirm the results. If the results are confirmed, it could mean development of one of the first vaccines to prevent cancer.
The vaccine was tested on more than one-thousand-five-hundred young women. They were between the ages of sixteen and twenty-five years old. About half of the women received three injections of the vaccine over six months. None of these women developed H-P-V-Sixteen infections or pre-cancerous growths on their cervix. The other women were injected with a harmless substance called a placebo. Forty-one women in this group developed H-P-V infections. Nine women developed abnormal cell growths on their cervix.
Researchers made the vaccine from a protein that forms on the outer part of the H-P-V Sixteen virus. This vaccine causes the body to produce large amounts of antibodies that fight the virus. Scientists say the ability to produce so many antibodies is unusual. Women receiving the vaccine showed about sixty times more antibodies in their blood than women who got the H-P-V Sixteen virus.
VOICE ONE:
Infection with the human papilloma virus is very common. There are thirty different forms of this virus. Not all cause cancer. Having the infection does not mean a woman will necessarily develop cervical cancer. This cancer can take many years to develop.
Still, reducing the risk of cervical cancer is a major medical goal. Cervical cancer kills about two-hundred-forty-thousand women in the world each year. Millions of American women have yearly tests for cervical cancer and abnormal growths. So the number of deaths from this cancer in the United States is small. However, most of the deaths from cervical cancer happen in developing countries where women are not tested for the disease. Cervical cancer kills more women than any other cancer in developing nations. Experts say vaccination could be a good way to prevent the disease in many parts of the world.
VOICE TWO:
Merck Research Laboratories says it is trying to produce an improved version of the vaccine. The National Cancer Institute and a private company in Maryland also are working to produce a vaccine. Some experts estimate that the general public may be able to get the vaccine by two-thousand-six.
Only one vaccine currently in use prevents cancer. It protects against hepatitis B, a virus that causes liver disease. Infection with hepatitis B causes many cases of liver cancer in Asia and Africa. Experts say rates of hepatitis B and liver cancer have dropped in areas with vaccination programs.
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VOICE ONE:
An American study has shown that a woman’s age need not stop her from having a baby. It found that women over the age of fifty can have healthy babies. However, older women’s bodies no longer release eggs, so they must use eggs provided by younger women.The findings were published in the Journal of the American Medical Association. The study is said to be the largest of its kind.
Scientists at the University of Southern California organized the study. They used a process called in-vitro fertilization. It was developed for younger women who are unable to have children.
VOICE TWO:
During in-vitro fertilization, scientists combine a woman’s egg and male reproductive fluid in a laboratory dish. Then, they place the fertilized egg in the woman’s uterus. There, the egg grows and develops into a fetus.
The California scientists used in-vitro fertilization in seventy-seven women between the ages of fifty and sixty-three. All of the women were in good health. They received eggs provided by younger women. Forty-two of the older women had babies. For twenty-six of the women, it was their first child.
Richard Paulson led the study. He says the findings provide evidence that women over the age of fifty can become pregnant. He said there is no medical reason for barring such women from attempting pregnancy only because of their age.
VOICE ONE:
However, the study also showed that pregnancies in older women often are linked with health problems. There were no deaths among the mothers or their babies. Yet, many of the women experienced medical problems during their pregnancy. For example, one-third of the women had high blood pressure. One-fifth developed the disease diabetes. Most of the women had their babies delivered by an operation called a cesarean section.
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VOICE TWO:
Silk is a material made mainly by silkworms. It is stronger than steel even though it is very thin. Silk can stretch more than many other materials without breaking. The most common use of silk is for cloth. However, scientists are interested in the possible use of silk for industrial and medical purposes.
Spiders also produce strong silk. They use it to build traps to capture insects. The traps hang in the air in complex designs called webs. Scientists consider some kinds of spider silk to be some of the strongest natural materials on Earth. However, unlike silkworms, spiders cannot be grown in large numbers on farms. This is because they attack and eat each other when put together. So it is almost impossible to get a large amount of spider silk naturally.
VOICE ONE:
Researchers are trying different ways to make spider silk. David Kaplan uses bacteria and genetic engineering. He works in the Department of Chemical and Biological Engineering at Tufts University in Medford, Massachusetts. Mister Kaplan copies or clones a spider gene responsible for producing silk.
He puts the gene copy into a bacterium such as E. coli. The bacterium grows into large numbers of bacteria. Later, small particles of silk are collected from the cells of the bacteria. Water is added to these particles and silk material is made from the mixture.
VOICE TWO:
Mister Kaplan notes that so far only small amounts of silk can be made by this method. However, a company called Nexia Biotechnologies says it can produce a lot more genetically engineered silk. The company is based in Montreal, Canada. It is one of the world’s largest producers of manmade silk.
The head of Nexia, Jeffrey Turner, says his researchers put the spider gene for silk-making into goats. The milk from these goats has silk proteins. Mister Turner says goats can produce a lot of silk because they grow and reproduce quickly.
VOICE ONE:
The main question now is how to get silk of good quality from silk protein. Scientists agree that it is the way silk worms and spiders combine or spin proteins that makes silk so strong. Researchers are trying to find ways to spin genetically produced silk the same way spiders and silkworms spin natural silk. Successful results could lead to stronger ropes, parachutes, and materials for use in medical operations.
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VOICE TWO:
This SCIENCE IN THE NEWS program was written by Jerilyn Watson, George Grow and Doreen Baingana. It was produced by George Grow. This is Bob Doughty.
VOICE ONE:
And this is Sarah Long. Join us again next week for more news about science in Special English on the Voice of America.