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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 Faith Lapidus. Our subject this week is medical transplant operations.

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Doctors perform transplants to replace organs or tissue in a person who is sick or injured.

There are records of a transplant operation that took place in eighteen-twenty-three. A German doctor, Carl Bunger, removed skin from a woman's leg and used it to rebuild her nose.

Scientists later showed that the defense system in the body tries to reject tissue transplanted from other people.

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Rejection continued to be a problem for transplants well into the twentieth century. In nineteen-fifty-eight, the French doctor Jean Dausset discovered a system to match tissue. This is a way to make sure that the tissue to be transplanted is closely similar to the patient's own.

In nineteen-seventy-two, the Swiss scientist Jean Borel discovered that the drug cyclosporine could stop the rejection. Cyclosporine is made from a fungus that lives in soil. Experts say this drug is the most important reason for the success of transplant operations today.

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More than twenty different organs and tissues can be transplanted from one person to another. Clinical Transplants is a publication that reports each year on the numbers of such operations around the world. It is published by researchers at U.C.L.A., the University of California, Los Angeles.

They say doctors performed more than fifty-thousand successful transplant operations in two-thousand-three. Close to thirty-thousand of these were kidney transplants. Kidneys are the organ most commonly transplanted.

The success rate of such transplants is very high. A family member often can provide a kidney for transplant. People have two kidneys, but usually need only one.

Some kidney transplant patients have survived for more than thirty years. A spokeswoman at U.C.L.A. says one transplanted kidney has been working for forty-one years.

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Another commonly transplanted organ is the liver. The liver is the only organ in the body that can grow to normal size from a small piece. Doctors can remove part of a liver from a person and place it into a patient who has liver failure.

After the operation, both livers will grow to full size. Clinical Transplants says more than ten-thousand liver transplants took place around the world in two-thousand-three.

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The South African doctor Christiaan Barnard did the first successful heart transplant. That happened in nineteen-sixty-seven.

Many more heart transplants have been done since nineteen-eighty-three. That was the year when the anti-rejection drug cyclosporine was approved for use in the United States. More than three-thousand heart transplants were performed around the world in two-thousand-three.

That same year, doctors also performed more than one-thousand lung transplants. Such operations can replace a single diseased lung or both lungs.

Sometimes, lung disease also damages the heart. So doctors must replace both the heart and the lungs.

Other organs that can be transplanted include the pancreas and the intestines.

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Doctors also perform tissue transplants. The most common is a blood transfusion. Blood is considered a tissue. People may receive blood after an operation or accident. Other tissue transplants include skin, bone marrow, blood vessels and corneas.

Corneal transplants improve the sight of people whose eyes have been damaged by injury or infection. Corneal transplants have a success rate of more than ninety percent.

Skin transplants reduce the chance of infection in areas of the body that have been burned. These transplants remain on the body for several weeks. This is done until skin from another part of the patient's own body can be used for a permanent transplant.

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Bone marrow transplants are for people who have disease such as leukemia, cancer of the blood. Doctors remove marrow from inside the hip bone of a healthy person. Then they place it into the sick person where the marrow begins to produce healthy blood cells.

Bones can be transplanted, too. Doctors have even transplanted hands and arms in several cases in Europe and the United States.

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A transplant operation succeeds only if doctors can prevent the body from rejecting the foreign organ or tissue. This is done with drugs like cyclosporine. Patients also must receive tissue that is similar to their own. The person who provides the organ or tissue is called the donor. The one who receives it is the recipient.

Both the donor and recipient must have the same blood type. For some transplants, they also must have some of the same proteins called H.L.A antigens. These are found on the outside of cells. Each person has many different H.L.A. antigens. The donor and recipient must have several of the same antigens for the transplant to have a chance to succeed.

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Family members are often the best possible choice for donors when a person needs a transplant. However, most transplanted organs come from people who have died or been declared brain dead. People who are brain dead usually suffered a head injury. After brain activity ends, doctors can keep the other organs alive with machines. This continues until transplant recipients are found.

In the United States, people who wish to donate their organs if they die in an accident can say so on their driving permit. Their families may also be asked for permission. A local medical organization will then do a computer search for people who need organs and have similar tissue.

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Transplants do not always have to come from other humans. Animal organs have also been transplanted into people. In nineteen-sixty-three and sixty-four, doctors in the United States placed kidneys from chimpanzees into six people. All the people died from infections. But one patient survived for nine months.

Doctors began to perform such operations because of the lack of human organs. Those who continue the research say they believe there will never be enough human organs to meet the need.

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Many researchers say pigs are the best animals for transplants. Heart valves from pigs are being used to replace diseased or damaged heart valves in people.

And scientists continue research to find ways to use pig cells to treat several diseases. These include diabetes, Parkinson's disease and Huntington's disease. Doctors say animal tissue could also be useful in countries where human-to-human transplants are not permitted.

One risk of human-to-human transplants is the spread of viruses. But some medical experts have similar concerns about the possible dangers of transplants from animals. Medical organizations around the world have developed rules about animal transplants. And there are moral issues. In some nations, animal rights groups strongly protest transplants from animals to humans.

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In the United States, there is a national list of people who need transplants. An organization called the United Network for Organ Sharing is responsible for this list.

The organization says about eighty-four-thousand people in the United States are waiting for transplants. It says more than five-thousand people each year die before a donor is found. The government has a Web site for people to learn more about organ donation. The address is organdonor-dot-g-o-v.

Organ and tissue shortages are a worldwide problem. Not surprisingly, some people see a chance to profit. There are illegal sellers of body parts.

Public health officials call organ donation the gift of life. They urge more people to consider giving this gift should they die unexpectedly.

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VOICE ONE:

SCIENCE IN THE NEWS was written by Nancy Steinbach. Cynthia Kirk was our producer. This is Bob Doughty.

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