Реферат по предмету "Иностранный язык"


Blood Of Children Sampling Essay Research Paper

Should parents pay a blood bank to store the blood from their newborn baby’s

umbilical cord and placenta, in case that child or another family member ever

needs it to treat cancer or leukemia? Expectant parents are being urged to do so

by companies that have sprung up during the past few years to sell cord-blood

banking as a form of "biological insurance" against such dreaded

diseases. The pitch is based on reports in medical journals, such as a major

study published last week in the New England Journal of Medicine, showing that

cord blood can sometimes be used in place of a bone marrow transplant. Like bone

marrow, cord blood is rich in stem cells, which can churn out many different

types of cells to rebuild a patient’s blood supply and immune system after high

doses of radiation and chemotherapy. And a patient’s own cord blood, or that

from a relative, is more likely than cord blood from an unrelated donor to be a

good tissue match and to be accepted by the recipient’s body. Some experts in

bone-marrow transplantation and blood banking frown on the cord-blood business,

arguing that people are being frightened into wasting money on a service they

will probably never need. Moreover, private companies are growing in tandem with

public banks, and some scientists worry that private banking will limit public

access to cord blood. They are concerned because the cord blood in private banks

remains the property of the donor family and is not available to patients

seeking a compatible donor. But the companies say that however remote the

possibility that the blood will be needed, people who choose to bank their own

cord blood have a right to do so. In most cases their cord blood would be thrown

away in the delivery room if they did not pay to bank it. There are only a few

cord-blood banks in the United States, and most hospitals do not have specially

trained staff members to collect the blood. Like bone marrow, cord blood must be

matched to the recipient by tests for six inherited traits that determine an

individual’s tissue type. Cord blood does not have to be as precisely matched as

bone marrow, but still, the closer the match, the better the odds of success.

The weaker the match, the more likely it is that the recipient’s body will

reject the transplant, or the transplant will attack the recipient’s tissues, in

a life-threatening reaction called graft versus host disease. The companies that

freeze cord blood and bank it point out that a person’s own cord blood is a

perfect match, and a sibling’s cord blood a more likely match than a specimen

from a stranger. And so, the argument goes, the best way to protect an entire

family from the unthinkable is to save the newborns’ cord blood. Promotional

literature for one company, Cord Blood Registry, in San Bruno, Calif.,

emphasizes that people with cancer in the family may have a special interest in

cord-blood banking, along with those who have the hardest time finding matches,

which includes members of racial minorities, especially families in which the

parents are of different races. According to a spokeswoman, Scoti Kaesshaefer,

the company reaches parents-to-be by promoting itself to doctors, nurses and

childbirth educators, and by leaving information at hospitals. Among the

promotional materials the company provided to the New York Times were copies of

articles from other newspapers suggesting that cancer among children is on the

rise. The company also has a Web site and an 800 number with a recorded greeting

that instructs callers to have their credit cards ready. The idea of saving

one’s own cord blood seems to be catching on. Cord Blood Registry, which

describes itself as the largest private cord-blood banking firm in the United

States, has stored 10,000 samples during the past three years: 1,500 in 1995,

3,000 in 1996 and 6,000 in 1997. The company charges an initial fee of $1,200 to

collect a sample and freeze it, and then $95 a year to keep it stored in liquid

nitrogen at the blood bank at the University of Arizona. Customers include

people with perfectly healthy children, who just want extra peace of mind, as

well as some families who have lost a child to leukemia or another disease and

fear for the health of their other children. In its three years of operation,

eight customers have retrieved their cord blood for use in medical treatment,

said Kaesshaefer. All eight samples were used for siblings or relatives, she

said. By contrast, the largest public-access bank of cord blood, at the New York

Blood Center in Manhattan, has collected only 8,686 specimens in six years. But

nearly 800 of those samples have been used to treat patients, many of them

children, in the United States and overseas. Critics of private cord-blood

companies point out that even if a person with banked cord blood does need a

transplant later, the stored blood may not be the best choice. Dr. Pablo

Rubinstein, who directs the cord-blood program at the New York Blood Center,

said there was a compelling medical argument against using a patient’s own cord

blood in some cases. In some young children with leukemia, he said, malignant

cells were already present at birth in the cord blood, and transfusing those

cells back into the child later might contribute to a relapse. In addition, he

said, bone marrow from a donor could help destroy diseased cells, an effect

known as graft versus leukemia. A person’s own cord blood might not have that

effect, and in some cases even a sibling’s might not. Dr. John Wagner, associate

director of bone marrow transplantation at the University of Minnesota in

Minneapolis, said that for a child being treated recently, he deliberately

rejected cord blood from a sibling in favor of a well-matched unit from an

unrelated donor, hoping to take advantage of its antileukemic effect. Dr.

Robertson Parkman, director of bone marrow transplantation at Children’s

Hospital in Los Angeles, said he saw no point in banking cord blood for most

families. "It’s motivated by fear," he said. But in families with an

ill child who might need a bone-marrow transplant, he said, it makes sense to

collect cord blood from any siblings born later and save it. Medical centers

with transplant programs will often perform that service, he said. So will some

of the private companies, without a fee. When a bone-marrow donor could not be

found for 4-year-old Joshua Kelton, who was suffering from leukemia, his

parents, stationed at a military base in Honolulu, conceived another child in

the hope that the baby’s tissues would match Joshua’s. They did, and Cord Blood

Registry collected the cord blood at birth, stored it in Arizona for a month,

and then, when Joshua was ready for the procedure, transported it to a medical

center at Stanford University. Joshua was treated with his infant brother’s cord

blood in August, and has been declared free of leukemia. "Right now, he’s

100 percent," his father said in a telephone interview, "a normal

child, the way he was before this happened." But the Keltons’ experience is

hardly representative. That the family was certain it would need the cord blood

sets it apart from most families that store the blood. Wagner is wary of the

hard sell of some of the cord-blood companies. "My concern is that it be

presented fairly to expectant mothers, who are already fairly vulnerable,"

he said. "I have a lot of obstetricians and parents calling me and

complaining it’s too late, they missed the opportunity. Others call saying,

‘Should I do this?’ It’s hard to answer. I don’t want to bias them. We have

someone now who takes the calls for me because it got to be overwhelming."




Не сдавайте скачаную работу преподавателю!
Данный реферат Вы можете использовать для подготовки курсовых проектов.

Поделись с друзьями, за репост + 100 мильонов к студенческой карме :

Пишем реферат самостоятельно:
! Как писать рефераты
Практические рекомендации по написанию студенческих рефератов.
! План реферата Краткий список разделов, отражающий структура и порядок работы над будующим рефератом.
! Введение реферата Вводная часть работы, в которой отражается цель и обозначается список задач.
! Заключение реферата В заключении подводятся итоги, описывается была ли достигнута поставленная цель, каковы результаты.
! Оформление рефератов Методические рекомендации по грамотному оформлению работы по ГОСТ.

Читайте также:
Виды рефератов Какими бывают рефераты по своему назначению и структуре.