SCIENCE IN THE NEWS - Easier Way to Treat Malaria | Scientis（在线收听）

SCIENCE IN THE NEWS - Easier Way to Treat Malaria | Scientists Grow Human Brain Cells in Mice
By Caty Weaver and Mario Ritter

Broadcast: Tuesday, December 20, 2005

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

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And I'm Pat Bodnar. This week on our show: Treating malaria an easier way ...

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Growing human brain cells in mice ...

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Mapping the genes of cancer ...

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And looking to the sky for the December solstice.

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A new treatment for malaria will combine the most effective drugs currently used. And it will be easier to take. A non-profit group called the Drugs for Neglected Diseases Initiative announced the news. It says the treatment will be ready by late next year, and will cost about half the price of current treatments.

 
Malaria, spread by mosquitoes, claims at least one million lives a year. Most who get sick enough from the infection to die are young children in Africa. 
The new treatment will combine artemisinin with one of two kinds of quinine-based drugs. Artemisinin is made from a Chinese plant. Two drug companies have agreed to produce the new treatment: Sanofi-Aventis of France and Far-Manguinhos of Brazil.

Those companies say they will try to keep the cost below one dollar. They also agreed not to earn a profit or seek patent protection for the new treatments. This means other companies will be able to make their own copies.

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Currently people have to take many pills to treat a malaria infection. The new treatment comes in one pill taken just two times a day for three days. Bernard Pecoul is director of the Drugs for Neglected Diseases Initiative. He says the simpler the treatment, the more likely people are to complete it.

Now, people commonly have to take two different kinds of pills for malaria. Successful treatment requires both. But only one has a pleasant taste. It also makes people feel better quickly. As a result, Doctor Pecoul says, people often take only that pill.

The new treatment avoids the situation. It combines the two drugs. The single pill will also use the newest medicines. Experts say this is important because the malaria parasite has developed resistance to older drugs. Yet those older drugs have often been the only ones priced low enough for poor countries to buy.

Doctor Pecoul says his group is seeking approval for the new combination treatment in countries with the highest rates of malaria. These are in Africa, Asia and Latin America.

Several public and private groups established the Drugs for Neglected Diseases Initiative in two thousand three. They include the World Health Organization and the French group Doctors Without Borders.

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

Scientists in La Jolla, California, say they have grown human brain cells in mice. The researchers at the Salk Institute used human stem cells in the process. Stem cells can develop into other kinds of cells, including brain cells.

The researchers say they placed about one hundred thousand stem cells into the brains of mouse embryos. The embryos were two weeks old. The researchers removed them from pregnant mice temporarily to inject the embryos with the stem cells.

The stem cells came from human embryos very early in their development. They were engineered to produce a green light. This made it easy to see which cells developed from the human material and which came from the mice.

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Professor Fred Gage led the research. He says most of the human stem cells did not survive. Less than one percent became human brain cells in the mice. But Mister Gage says those that did survive developed into fully active brain cells.

The professor says the human brain cells adapted to their new environment. They moved around and settled into different areas of the mouse brain. They grew to the size and shape of the surrounding brain cells.

The scientists say they are not sure how or why this happened. But Professor Gage says it shows that injecting human stem cells into a mouse brain does not restructure the brain.

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Similar studies in the past used older stem cells and adult mice. Many times the cells formed tumor growths. Other times the mouse's body simply rejected the human cells.

The scientists at the Salk Institute in California say no such problems appeared when they injected young stem cells into unborn mice. Researcher Allyson Moutri says the findings could lead to new ways to study human disease. The scientists say their work could help speed the testing of drugs to treat diseases that destroy the brain.

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Each year around December twenty-first the sun reaches its southernmost position in the sky. This event is called a solstice. The December solstice marks the beginning of winter for people in the northern half of the world. And it marks the beginning of summer for people in the southern half.

The word solstice comes from French and Latin. It describes a time when the sun appears to stand still as it moves to the north or south. We usually think of the sun as moving only east to west. That gives us day and night. But a slow movement northward and southward gives us our seasons. Really, to be exact, we should say apparent movement.

People used to think the sun orbited the Earth, not the opposite. And how long does one orbit take? It takes one year.

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Between the south pole and the north pole is an axis. Earth turns around this imaginary line. The axis is fixed in space in one direction. But as our planet moves through space, that direction changes in relation to the sun.

At the June solstice, the southern hemisphere is pointed away from the sun by about twenty-three degrees. At the December solstice, the southern hemisphere is pointed about twenty-three degrees toward the sun.

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People who live near the equator have days and nights of fairly equal length all year. They are said to live in the tropics -- that is, the area between the Tropic of Cancer and the Tropic of Capricorn. These are simply lines of latitude, lines that measure a position on a map in terms of degrees. If you live between the lines, the seasons all seem pretty much the same.

The June solstice takes place when the sun is directly overhead at the Tropic of Cancer. The Tropic of Cancer is about the same northern latitude as Havana, Cuba. On that day, usually June twenty-first, the sun appears at its northernmost position in the sky.

At the December solstice, the sun is directly overhead at the Tropic of Capricorn, the same southern latitude as Sao Paulo, Brazil.

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While the southern half of the world enjoys long days, people in the north have long nights. And the farther north, the longer the nights. Without sunlight, temperatures drop. So our seasons and the length of our days are linked.

The Naval Observatory in Washington says winter solstice will take place at eighteen hours thirty-five Universal Time Wednesday.

Here in Washington, we will have about nine-and-a-half hours of daylight. People in Reykjavik, Iceland, will have less than four hours of sun. If you live in Murmansk, Russia, the sun will not rise at all on the day of the solstice. In fact, you would have last seen the sun on December third. And you will not see it again until January seventh.

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In recent years, scientists have made important progress in studying genetics. In two thousand three, they completed the Human Genome Project -- a map of the genes that make a person.

Now, researchers in the United States plan to do the same with cancer. Experts say more than two hundred different diseases are now defined as cancer. And they say all forms of cancer involve genetic changes.

Last week, the National Institutes of Health announced plans for the Cancer Genome Atlas. Doctor Elias Zerhouni, the director of N.I.H., says maps of cancer genes could lead to major improvements in testing and treatment. He says the atlas could also lead to new methods for cancer prevention.

The effort will begin with a three-year test project at a cost of one hundred million dollars.

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Our program was written by Caty Weaver, Jerilyn Watson and Mario Ritter. Cynthia Kirk was our producer. And our thanks to astronomer Mark Stollberg at the Naval Observatory. I'm Pat Bodnar.

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And I'm Bob Doughty. Internet users can read and listen to our programs at www.tingroom.com. Join us again next week for SCIENCE IN THE NEWS in VOA Special English.