This is
SCIENCE IN THE NEWS, in VOA Special English.
I'm Barbara Klein.
VOICE TWO:
And I'm Bob
Doughty. On our program this week, we tell
about medical transplant (移植) operations.
Doctors perform transplant operations to
replace tissue or organs in a person who is
sick or injured. Organ transplants help save
thousands of lives each year.
(MUSIC)
VOICE ONE:
Last year
marked the fiftieth anniversary of the first
successful transplant of a human organ. An
American medical team performed the first
successful organ transplant (器官移植) on
December twenty-third, nineteen fifty-four.
The operation took place at what is now
Brigham and Women's Hospital in Boston,
Massachusetts.
The patient,
Richard Herrick, was dying from a kidney
infection (腎臟發炎). Doctor Joseph Murray led
the team that gave Richard a kidney from his
twin brother, Ronald. Ronald had the same
genes (基因)as Richard, but was in excellent
health. Richard survived for eight more
years with the kidney. In nineteen-ninety,
Doctor Murray was given the Nobel Prize in
Medicine for his work.
VOICE TWO:
Experts say
the first transplant operation was carried
out in eighteen twenty-three. A German
doctor placed skin from a woman's leg on her
nose. By eighteen sixty-three, a French
scientist showed that the body rejects
(排斥)tissue transplants from one person to
another. Forty years later, a German
scientist found that this rejection was
carried out by the body's defense system
(防衛系統) attacking the foreign (外來) 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.
VOICE ONE:
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 (菌) 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. American
officials say a record number of organ
transplants were performed in the United
States last year. Nearly twenty-seven
thousand people received one or more organs.
These people can be expected to survive for
many years.
(MUSIC)
VOICE TWO:
More than
twenty different organs and tissues can be
transplanted from one person to another. The
organ most commonly transplanted is the
kidney. The success rate of kidney
transplants is very high. Some kidney
transplant patients have survived for more
than forty years.
Another
commonly transplanted organ is the liver. It
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.
VOICE ONE:
The South
African doctor Christiaan Barnard performed
the first successful heart transplant in
nineteen sixty-seven. Many more heart
transplants have been done since
cyclosporine was approved for use.
Experts say
the number of heart transplants decreased
last year. They say the demand for heart
transplants has slowed because of
improvements in medical processes and better
treatments for heart disease.
Sometimes,
lung disease damages the heart. So doctors
must replace both the heart and the lungs.
The pancreas (胰腺) and the intestines (腸) are
two other organs that can be transplanted.
VOICE TWO:
Doctors also
perform tissue transplants. The most common
is a blood transfusion. People may receive
blood after an operation or accident. Blood
is considered a tissue. Other tissue
transplants involve skin, bone marrow(骨髓),
blood vessels and corneas.
Corneal (角膜的)
transplants improve the sight of people
whose eyes have been damaged by injury or
infection. Such operations have a success
rate of more than ninety percent.
VOICE ONE:
Skin
transplants reduce the chance of infection
in severely burned areas of skin. These
transplants remain on the body for several
weeks. This is done until skin from another
part of the patient's body can be used for a
permanent transplant.
Bone marrow
transplants are for people who have diseases
such as leukemia (血癌), a cancer of the
blood. Doctors remove marrow from 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. In some countries,
doctors have even transplanted arms and
hands.
(MUSIC)
VOICE TWO:
A transplant
operation is successful 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 tissue or
organ is known as the donor. The one
receiving it is the recipient.
Both the donor
(捐贈者) and recipient must have similar blood.
For some transplants, they also must have
some of the same proteins called H.L.A.
antigens (抗原). 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.
VOICE ONE:
Family members
are often the best choice for a donor 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 use machines to keep the other
organs working. This continues until a
transplant recipient is found.
In the United
States, a private group keeps a national
list of persons who need a transplant. It is
called the United Network for Organ Sharing,
or UNOS. It says the number of persons
waiting for organ transplants has risen
sharply in the past fifteen years.
At the time,
there were about twenty thousand people on
the waiting list. There are about eighty
nine thousand now. Each year, more than six
thousand Americans die before the organ they
need is found.
VOICE TWO:
Efforts to increase the
number of organ donors have helped to reduce
the waiting time. UNOS says transplant
operations in the United States last year
used almost as many organs from living
donors as from people who had died.
Kidneys can
come from a living donor because a person
can live with only one. Living donors can
also give part of their liver, pancreas,
intestine or a piece of a lung.
(MUSIC)
VOICE ONE:
Organ and
tissue shortages are a worldwide problem.
The shortage of organs has led health
officials to begin easing rules about who
can give an organ. Some doctors have started
accepting organs once considered unusable.
Not
surprisingly, some people see a chance for
profit. Each year, hundreds of poor people
illegally sell their kidneys for later use
in transplant operations.
VOICE TWO:
Some animal
organs have been experimentally transplanted
into people. Doctors began to perform such
operations because of the lack of human
organs. Those who continue the experiments
say they believe there will never be enough
human organs to meet the need.
Many
scientists say pigs are the best animals for
transplants. Heart valves (瓣膜) from pigs are
being used to replace diseased or damaged
heart valves in people. Scientists say
animal tissue could also be useful in
countries where human-to-human transplants
are not permitted.
VOICE ONE:
Health care
workers around the world say organ and
tissue transplants save thousands of lives.
Some officials call organ donation the gift
of life. They urge people to consider giving
permission to use their organs for
transplant operations if they should die
unexpectedly.
In the United
States, people who wish to donate their
organs if they die in an accident can state
so on their driving permit. A medical
organization will then do a computer search
for people who need organs and have similar
tissue.
(MUSIC)
VOICE TWO:
This SCIENCE
IN THE NEWS was written and produced by
Cynthia Kirk. I'm Bob Doughty.
VOICE ONE:
And I'm
Barbara Klein. Join us again next week for
more news about science in Special English
on the Voice of America.
