Science News Digest

This is Sarah Long. And this is Bob Doughty with SCIENCE IN THE NEWS, a VOA Special English program about recent developments in science. Today, we tell about new treatments for cancer … a way to prevent a baby from having a terrible disease … new research about an ancient dinosaur … and how to become a space tourist.

The United States Food and Drug Administration has approved a new kind of drug that uses radiation to kill cancer cells. Current chemotherapy drugs are effective at killing cancer cells. But they also kill healthy, normal cells. This leads to pain, organ damage and other physical problems for cancer patients.

The new kind of drug affects only cancer cells. Doctors say the drugs could someday end the unwanted side effects of cancer treatment. Patients would feel better and be able to take even more anti-cancer drugs that would improve their chances for survival.

One new kind of drug works by placing a radioactive substance onto a genetically engineered protein, or antibody. The antibody moves through the patient's blood, attaches to cancer cells and kills them. This treatment is called radioimmunotherapy. Researchers say such drugs can be developed to fight many kinds of cancer.

The newest such drug to be approved is called Zevalin. It is for people who have a cancer of the white blood cells called non-Hodgkin's lymphoma and have not been helped by other drug treatments. Zevalin carries radioactive particles to the cancer cells and kills them. Doctors say the patient's body then develops healthy, new white blood cells. The treatment particles lose their radioactivity after several days or weeks.

Tests have showed that Zevalin reduced cancer tumors in about seventy-five percent of patients. The cancer completely disappeared in as many as thirty percent of the people treated with Zevalin in the tests.

Zevalin does cause other effects on the body, however. These include stomach problems and reduction of while blood cells. This makes the patient more likely to suffer infections. However, some researchers say these effects are less harmful than those caused by drugs now used to treat cancer.

A similar kind of treatment uses powerful magnets to pull drug particles into cancerous growths. Researchers from drug companies are testing this treatment on patients with liver cancer in China. They are also planning a larger international test.

Another kind of cancer treatment uses laser light to cause chemical reactions in drugs that kill cancer cells. This light treatment does not affect nearby healthy tissue.

Doctors in Chicago, Illinois, have helped a woman have a baby who is free of the risk of developing early Alzheimer's disease.

The medical name for this kind of genetic engineering is pre-implantation genetic diagnosis. It has been done to prevent diseases that are passed from parents to their children. These diseases include hemophilia, sickle cell anemia, muscular dystrophy, Tay-Sachs disease, cystic fibrosis and Huntington's disease.

In this process, doctors test a woman's eggs or embryos for genes that carry the disease. Only those embryos without the genes are placed in the woman's uterus to develop into a baby.

The woman in the latest example of pre-implantation diagnosis is an expert in genetics. She is thirty years old. Her family carries a gene that causes an extremely rare form of Alzheimer's disease. It causes severe memory loss and mental disability at an early age. The woman's father, sister and brother all developed this early Alzheimer's disease when they were in their thirties. Her father died at the age of forty-two.

The woman also carries the gene. She did not want to pass it on to her children. She also did not want to become pregnant and then have the fetus tested for the early Alzheimer's gene.

The woman and her husband sought help from Yury Verlinsky and his team at the Reproductive Genetics Institute in Chicago. The doctors treated her with hormones. She produced twenty-three eggs. Tests showed which were free of the early Alzheimer's gene. These were fertilized with her husband's sperm and placed in her uterus.

She gave birth to a healthy baby girl about eighteen months ago. The baby does not have the gene for the disease. The doctors reported the work in the Journal of the American Medical Association. They say it is the first use of genetic engineering to prevent early Alzheimer's disease in a family.

Some doctors have praised the work as a way to end the continuing tragedy of a disease passed from parents to children. Other experts have criticized it as a step toward designing babies. Critics also noted that the woman would soon be unable to care for her child and would die before the child has grown up. However, Doctor Verlinsky said many children have only one parent.

Experts say this process would not be used for most people who have a family member with Alzheimer's disease. The more common kinds of Alzheimer's disease happen much later in life. And they are not caused by only one gene.

Ancient animals called dinosaurs have captured the imagination of millions of people around the world. The huge dinosaur Tyrannosaurus rex has even been in popular American movies like "Jurassic Park." In some movies, Tyrannosaurus rex is shown running at top speed after cars and helicopters. The Tyrannosaurus in the movies is a terrible combination of speed and power.

Yet two biological scientists say this is probably wrong. They are John Hutchinson of Stanford University in California and Mariano Garcia of Cornell University in Ithaca, New York. Their research suggests that Tyrannosaurus rex could only walk slowly.

Mr. Hutchinson and Mr. Garcia used a biological computer model to study the bones of the ancient creature. They found that the legs of Tyrannosaurus were not strong enough for the animal to be able to run fast.

The meat-eating dinosaur weighed almost six-thousand kilograms. Mr. Hutchinson says the animal's legs would have had to be huge to enable the creature to run fast. He says its leg muscles would have had to be eighty-five percent of its total weight.

The findings of the two biological scientists conflict with current scientific information about Tyrannosaurus. Until now, many scientists believed that the huge dinosaur could run up to seventy kilometers an hour.

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Would you like to orbit the Earth inside the International Space Station? Now you can take a space holiday—for a price. This is due to a recent decision by top space officials of the United States, Russia, Canada, Japan and the European Space Agency.

Last April, American businessman Dennis Tito reportedly paid between twelve-million and twenty-million dollars to spend one week on the International Space Station. The American Space Agency had strongly objected to the Russian plan to permit a civilian on the costly research vehicle.

After two years of negotiations, however, space officials have agreed on a process to train private citizens to take trips to the International Space Station.

NASA recently agreed to conditions that will permit Russia to sell trips to the space station. An American company called Space Adventures Limited of Arlington, Virginia, is planning the trips. The company has sold a space trip to Mark Shuttleworth, a South African businessman. Next month, Mr. Shuttleworth will be launched into space from the Baikonur Cosmodrome in Kazakhstan.

Experts say the change in policy at NASA shows a new desire to use space vehicles for business and industrial purposes. Yet, the average citizen will not be able to travel into space in the near future. Space Adventures Limited sells a training program for space flight that costs two-hundred-thousand dollars. That price does not include the cost of the trip to the International Space Station. That holiday in space costs twenty-million dollars.

This SCIENCE IN THE NEWS program was written by Nancy Steinbach and Mario Ritter. It was produced by Cynthia Kirk. This is Sarah Long. And this is Bob Doughty. Join us again next week for more news about science in Special English on the Voice of America.