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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.
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This Science Report is published courtesy
of VOAnews.com
