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

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And I'm Faith Lapidus. Our subject this week is medicaltransplant operations.

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

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

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

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Rejection continued to be a problem for transplants well into thetwentieth century. In nineteen-fifty-eight, the French doctor JeanDausset discovered a system to match tissue. This is a way to makesure that the tissue to be transplanted is closely similar to thepatient's own.

In nineteen-seventy-two, the Swiss scientist Jean Boreldiscovered that the drug cyclosporine could stop the rejection.Cyclosporine is made from a fungus that lives in soil. Experts saythis drug is the most important reason for the success of transplantoperations today.

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

They say doctors performed more than fifty-thousand successfultransplant operations in two-thousand-three. Close tothirty-thousand of these were kidney transplants. Kidneys are theorgan most commonly transplanted.

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

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

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

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

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

Many more heart transplants have been done sincenineteen-eighty-three. That was the year when the anti-rejectiondrug cyclosporine was approved for use in the United States. Morethan three-thousand heart transplants were performed around theworld in two-thousand-three.

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

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

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

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

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

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

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

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

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

Both the donor and recipient must have the same blood type. Forsome transplants, they also must have some of the same proteinscalled H.L.A antigens. These are found on the outside of cells. Eachperson has many different H.L.A. antigens. The donor and recipientmust have several of the same antigens for the transplant to have achance to succeed.

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Family members are often the best possible choice for donors whena person needs a transplant. However, most transplanted organs comefrom people who have died or been declared brain dead. People whoare brain dead usually suffered a head injury. After brain activityends, doctors can keep the other organs alive with machines. Thiscontinues until transplant recipients are found.

In the United States, people who wish to donate their organs ifthey die in an accident can say so on their driving permit. Theirfamilies may also be asked for permission. A local medicalorganization will then do a computer search for people who needorgans and have similar tissue.

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Transplants do not always have to come from other humans. Animalorgans have also been transplanted into people. Innineteen-sixty-three and sixty-four, doctors in the United Statesplaced kidneys from chimpanzees into six people. All the people diedfrom infections. But one patient survived for nine months.

Doctors began to perform such operations because of the lack ofhuman organs. Those who continue the research say they believe therewill 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 damagedheart valves in people.

And scientists continue research to find ways to use pig cells totreat several diseases. These include diabetes, Parkinson's diseaseand Huntington's disease. Doctors say animal tissue could also beuseful in countries where human-to-human transplants are notpermitted.

One risk of human-to-human transplants is the spread of viruses.But some medical experts have similar concerns about the possibledangers of transplants from animals. Medical organizations aroundthe world have developed rules about animal transplants. And thereare moral issues. In some nations, animal rights groups stronglyprotest transplants from animals to humans.

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In the United States, there is a national list of people who needtransplants. An organization called the United Network for OrganSharing is responsible for this list.

The organization says about eighty-four-thousand people in theUnited States are waiting for transplants. It says more thanfive-thousand people each year die before a donor is found. Thegovernment has a Web site for people to learn more about organdonation. The address is organdonor-dot-g-o-v.

Organ and tissue shortages are a worldwide problem. Notsurprisingly, some people see a chance to profit. There are illegalsellers of body parts.

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

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VOICE ONE:

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

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