This is Doug Johnson. And this is Bob Doughty with SCIENCE IN THE NEWS, a VOA Special English program about recent developments in science. Today, we tell about medical transplant operations.
Doctors perform medical transplant operations to place tissue or organs into the body of an injured or sick person.
Medical history experts say the first transplant operation was carried out in Eighteen-Twenty-Three. A German doctor placed skin from a woman's leg onto her nose. By Eighteen-Sixty-Three, French scientist Paul Bert showed that the body rejects tissue transplants from one person to another. Forty years later, German scientist Carl Jensen found that this rejection was carried out by the body's defense system attacking the foreign tissue.
Rejection continued to be a problem well into the twentieth century. In Nineteen-Fifty-Eight, French doctor Jean Dausset discovered a system for tissue matching. This is a way to make sure that the tissue to be transplanted is as similar as possible to the patient's own tissue.
In Nineteen-Seventy-Two, Swiss scientist Jean Borel discovered that the drug cyclosporine could stop the body from rejecting the new organ or tissue. Cyclosporine is a natural product made from a fungus found in soil.
Cyclosporine was approved for use in the United States in Nineteen-Eighty-Three. Experts say the use of this drug is the most important reason for the success of transplant operations today.
Doctors around the world now can save thousands of lives with transplant operations. Each year, more than twenty-thousand organs are successfully transplanted into patients in the United States alone. These people can be expected to survive for many years.
At least twenty-one different organs and tissues can be successfully transplanted into the bodies of patients. The most common organ transplanted is a kidney. A scientific report on transplants said more than twenty-four-thousand kidney transplants are performed around the world each year. The success rate of these transplants is very high.
Some kidney transplant patients have survived for more than thirty years. A family member often can provide a kidney for transplant because people have two kidneys but need only one.
The liver is the only human internal organ that can grow to normal size from a small piece. That is why it is possible to remove part of a liver from a living person and place it in the body of a person suffering liver failure. After the operation, both livers will grow to full size. More than seven-thousand liver transplants are performed around the world each year.
The first successful heart transplant was done in Nineteen-Sixty-Seven by South African doctor Christiaan Barnard. Many more heart transplant operations have been done since Nineteen-Eighty-Three, when cyclosporine was approved for use in the United States. About three-thousand heart transplants are performed around the world each year.
Lung transplants can replace a single diseased lung or both lungs. About one-thousand lung transplants are performed each year.
Sometimes, lung disease has also damaged the heart, and both organs must be replaced.
Tissue also can be transplanted. The most common tissue transplant is a blood transfusion when a patient receives blood after an operation or accident. Other tissues that are transplanted include corneas of the eye, skin, bone marrow, bone and blood vessels.
Corneal transplants improve the sight of people whose corneas have been damaged or destroyed 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, until skin from another part of the patient's body can be used for a permanent transplant.
A bone marrow transplant treats people suffering from cancer of the blood and other diseases. Doctors remove the substance inside the hip bone of a healthy person and place the bone marrow in a sick person's body. The marrow then begins producing healthy blood cells.
Bones can be transplanted, too. Recently, doctors have even transplanted hands and arms onto several patients in Europe and the United States.
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. The patient also must receive tissue that is similar to his or her own. The person providing the organ or tissue is known as the donor. The one receiving 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. H-L-A antigens 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.
Family members are the best possible organ donors. Other healthy people also can provide organs. However, most transplanted organs come from people who have died or are brain dead. People who are brain dead usually were in a serious accident that injured the head. After the brain dies, doctors keep the other parts of the body alive with machines.
The family of the accident victim must give permission for transplanting the victim's organs. Then a local medical organization makes a computerized search for a person who needs the organ and who has tissue similar to the victim. Doctors remove the organs from the body and send them to the recipient's hospital.
Animal organs also have been transplanted into people. In Nineteen-Sixty-Three and Nineteen-Sixty-Four, doctors in the United States placed kidneys from chimpanzees into six people. All the people died from infections. However, one patient survived for nine months.
Doctors began performing such operations because of the lack of human organs. Those who continue the research today say they believe there never will be enough human organs for transplant operations.
Many researchers now 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 are continuing 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 transplantation could be very useful in countries where human-to-human transplants are not permitted.
However, some medical experts are concerned about the possible dangers of animal transplants. These include the possibility of releasing a virus like the one that causes the disease AIDS. Medical organizations all over the world have developed rules about animal transplants. In some nations, animal rights groups strongly protest transplants of animals to humans.
The United Network for Organ Sharing is the organization in the United States that keeps the national list of patients needing transplants.
The organization says about seventy-thousand people are waiting for organ transplants in the United States. It says more than six-thousand people died while waiting for an organ transplant in the United States last year.
Health care workers around the world say organ and tissue transplants save thousands of lives. They urge people to consider giving permission to use their organs for transplant operations if they should die unexpectedly in an accident.
This SCIENCE IN THE NEWS program was written by Nancy Steinbach. This is Doug Johnson. And this is Bob Doughty. Join us again next week for more news about science in Special English on the Voice of America.