SCIENCE IN THE NEWS - U.S. Scientists Find a Way to Create E

SCIENCE IN THE NEWS - U.S. Scientists Find a Way to Create Embryonic¹ Stem Cells With Adult Skin Cells
By Cynthia Kirk, Nancy Steinbach, and Caty Weaver²

Broadcast: Tuesday, August 30, 2005

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VOICE ONE:

This is SCIENCE IN THE NEWS in V.O.A. Special English. I'm Bob Doughty³.

VOICE TWO:

And I'm Barbara Klein. This week, we tell how blood from crocodiles could help people. We also will describe an experimental treatment for burn victims.

VOICE ONE:

 
 
But first, we tell how American scientists turned human skin cells into what appear to be embryonic stem cells.

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VOICE ONE:

Last week, scientists at Harvard University in Massachusetts reported progress in embryonic stem cell research. The scientists said they joined an embryonic stem cell with a normal skin cell to create a new embryonic stem cell. They said their method could provide a way to make embryonic stem cells without having to destroy fertilized⁴ human eggs called embryos⁵.

The destruction of human embryos is hotly debated in a number of countries, including the United States. Many people object to experiments using human embryos for religious or moral reasons. American law restricts the use of federal money for research involving embryos.

VOICE TWO:

Stem cells are able to develop into any other kind of cell or tissue. Those taken from embryos are considered the most useful. Researchers believe they could use embryonic stem cells to treat some diseases and even injuries.

The Harvard University said they joined, or fused, a skin cell with an embryonic stem cell. They said the fusing process caused the stem cell to reset⁶ the genes⁷ in the skin cell. In simple terms, the skin cell was changed into an embryonic stem cell.

Chad Cowan took part in the Harvard study. He says it should be possible to develop replacement⁸ cells or even grow organs from the newly created stem cells. But, he and other members of the Harvard team say such possible uses are many years away.

VOICE ONE:

The scientists said they grew embryos from human eggs they received from a private organization. They also said they got similar results in experiments when they used embryonic stem cells federally approved for research. Mister Cowan said he believes most people will find this way of producing embryonic stem cells morally acceptable.

The scientists still face a major problem. The cell contains two groups, or sets, of genetic⁹ information. One set is from the skin cell. The other is from the starter embryonic stem cell. For any medical purpose, doctors would only want the genetic material of the patient to remain.

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VOICE TWO:

Scientists in Switzerland say they have used skin cells grown from a fetus¹⁰ to treat burns in children. The scientists say their method can produce a quicker and more complete recovery than current treatments.

The British medical publication, The Lancet, reported the findings.

The burn patients were eight children between the ages of fourteen months and nine years. All eight had either burns of the highest severity or what experts call deep partial-thickness burns. The fetal cells came from a woman whose pregnancy¹¹ was ended at fourteen weeks. The woman gave the scientists permission to use four centimeters of skin from her fetus.

VOICE ONE:

The scientists let the fetal cells divide in a laboratory. Then they mixed the cells with the protein collagen. Collagen is a substance that enables skin to stretch. The scientists say this process can provide many small pieces of skin tissue.

The scientists placed some of the pieces on top of the wounds of the children. As the tissue cells weakened, they were replaced with other pieces of tissue every three to four days. The scientists say the process was not difficult. They simply covered the wound with a piece of cloth.

VOICE TWO:

Usually, doctors use skin from other parts of a patient's body to repair damage from burns. However, those skin cells reproduce slowly and sometimes painfully. And, the new skin often looks strange. That process is called grafting¹³.

Patrick Hohlfeld of the University Hospital of Lausanne led the study. He said his team expected the fetal tissue to work much the same way. But, he said they were surprised by how much better it treated the wounds.

VOICE ONE:

The report says the wounds on the young burn patients healed in about fifteen days. Most graft¹² treatments take six times longer. And, the scientists say the repairs were complete. Most patients recovered full use of their damaged body parts. Their progress was observed for up to two years after being treated.

Other researchers say the results of the Swiss experiment still need to be compared to current medical treatments for burns. They noted¹⁴ that no one knows if the burns on the children would have healed on their own without the fetal cell treatment.

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VOICE TWO:

Scientists in northern Australia hope to use blood from crocodiles to develop new medicines for people. The scientists have been collecting blood from live crocodiles after capturing them and tying their mouths closed. They put a small instrument in the back of the animal's neck to get the blood.

The scientists hope to separate antibodies from the blood and develop drugs for human use. Antibodies are proteins that attack diseases inside the body. The scientists say they hope their work leads to development of antibiotic¹⁵ pills and liquids that you could put on wounds.

VOICE ONE:

Earlier studies found that several proteins in crocodile blood killed bacteria that resist the drug penicillin¹⁶. Recent tests have shown that the proteins also can kill the virus that causes AIDS.

The scientists say a crocodile's defense¹⁷ system against disease is much more powerful than that of the human body's defense system. They say the defense system of the crocodile attacks bacteria immediately when the body is infected. The defense system reportedly joins with the bacteria and tears it apart.

VOICE TWO:

Scientist Adam Britton has been collecting blood from both salt-water and freshwater crocodiles. He says scientists might need years to create any medicine for people because the animal's defense system is so powerful.

However, other scientists say the human defense system will recognize the crocodile antibodies as foreign and attack them. They say this could cause serious health problems.

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VOICE ONE:

Scientists say they have developed a new cancer drug. They have tested it in only in laboratory animals. The drug is designed to invade and kill cancer cells but not healthy cells. First, the drug enters the cancer and destroys the supply of blood. Then it releases poison to destroy the cancer cells.

Researchers at the Massachusetts Institute of Technology in Cambridge carried out the study. The results appeared in Nature magazine.

VOICE TWO:

Ram¹⁸ Sasisekharan is a professor at M.I.T. He says his team had to solve three problems. They had to find a way to destroy the blood passages, then to prevent the growth of new ones. But they also needed the blood passages to supply chemicals to destroy the cancer.

So, the researchers designed a two-part "nanocell." The cell is measured in nanometers, or one thousand-millionth of a meter. The particle used was two hundred nanometers -- much, much smaller than a human hair.

The researchers say it was small enough to pass through the blood vessels¹⁹ of the cancer. But it was too big to enter normal blood vessels. The surface of the nanocells also helped them to avoid natural defenses.

VOICE ONE:

The scientists designed the cell as a balloon inside a balloon. They loaded the outer part with a drug that caused the blood vessels to fall in on themselves. That cut off the blood supply and trapped the nanocell inside the cancer. Then, the nanocell slowly released chemotherapy drugs to kill the cancer cells.

The team says the treatment reduced the size of the cancer and avoided healthy cells better than other treatments. The scientists say mice with the best current treatments lived thirty days. But they say eighty percent of the mice treated with the nanocells lived more than sixty-five days.

The study involved two different forms of cancer. The team says the treatment worked better against melanoma, a deadly skin cancer, than against lung cancer. However, more studies are needed before the new drug can be tested in humans.

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VOICE TWO:

This SCIENCE IN THE NEWS program was written by Cynthia Kirk, Nancy Steinbach, and Caty Weaver. Cynthia Kirk was our producer. I'm Barbara Klein.

VOICE ONE:

And I'm Bob Doughty. Join us again next week at this time for more news about science on the Voice of America.

1 embryonic   

adj.胚胎的

参考例句：

• It is still in an embryonic stage.它还处于萌芽阶段。
• The plan,as yet,only exists in embryonic form.这个计划迄今为止还只是在酝酿之中。

2 weaver   

n.织布工；编织者

参考例句：

• She was a fast weaver and the cloth was very good.她织布织得很快，而且布的质量很好。
• The eager weaver did not notice my confusion.热心的纺织工人没有注意到我的狼狈相。

3 doughty   

adj.勇猛的，坚强的

参考例句：

• Most of successful men have the characteristics of contumacy and doughty.绝大多数成功人士都有共同的特质：脾气倔强，性格刚强。
• The doughty old man battled his illness with fierce determination.坚强的老人用巨大毅力与疾病作斗争。

4 Fertilized   

v.施肥( fertilize的过去式和过去分词 )

参考例句：

• The study of psychology has recently been widely cross-fertilized by new discoveries in genetics. 心理学研究最近从遗传学的新发现中受益匪浅。
• Flowers are often fertilized by bees as they gather nectar. 花常在蜜蜂采蜜时受粉。

5 embryos   

n.晶胚；胚，胚胎( embryo的名词复数 )

参考例句：

• Somatic cells of angiosperms enter a regenerative phase and behave like embryos. 被子植物体细胞进入一个生殖阶段，而且其行为象胚。 来自辞典例句
• Evolution can explain why human embryos look like gilled fishes. 进化论能够解释为什么人类的胚胎看起来象除去了内脏的鱼一样。 来自辞典例句

6 reset   

v.重新安排，复位；n.重新放置；重放之物

参考例句：

• As soon as you arrive at your destination,step out of the aircraft and reset your wristwatch.你一到达目的地，就走出飞机并重新设置手表时间。
• He is recovering from an operation to reset his arm.他做了一个手臂复位手术，正在恢复。

7 genes   

n.基因( gene的名词复数 )

参考例句：

• You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因，所以能够活得很长。 来自《简明英汉词典》
• Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪

8 replacement   

n.取代，替换，交换；替代品，代用品

参考例句：

• We are hard put to find a replacement for our assistant.我们很难找到一个人来代替我们的助手。
• They put all the students through the replacement examination.他们让所有的学生参加分班考试。

9 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。

10 fetus   

n.胎，胎儿

参考例句：

• In the fetus,blood cells are formed in different sites at different ages.胎儿的血细胞在不同时期生成在不同的部位。
• No one knows why a fetus is not automatically rejected by the mother's immune system. 没有人知道为什么母亲的免疫系统不会自动排斥胎儿。

11 pregnancy   

n.怀孕，怀孕期

参考例句：

• Early pregnancy is often accompanied by nausea.怀孕早期常有恶心的现象。
• Smoking during pregnancy increases the risk of miscarriage.怀孕期吸烟会增加流产的危险。

12 graft   

n.移植，嫁接，艰苦工作，贪污；v.移植，嫁接

参考例句：

• I am having a skin graft on my arm soon.我马上就要接受手臂的皮肤移植手术。
• The minister became rich through graft.这位部长透过贪污受贿致富。

13 grafting   

嫁接法，移植法

参考例句：

• Even grafting new blood vessels in place of the diseased coronary arteries has been tried. 甚至移植新血管代替不健康的冠状动脉的方法都已经试过。
• Burns can often be cured by grafting on skin from another part of the same body. 烧伤常常可以用移植身体其它部位的皮肤来治愈。

14 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。

15 antibiotic   

adj.抗菌的；n.抗生素

参考例句：

• The doctor said that I should take some antibiotic.医生说我应该服些用抗生素。
• Antibiotic can be used against infection.抗菌素可以用来防止感染。

16 penicillin   

n.青霉素，盘尼西林

参考例句：

• I should have asked him for a shot of penicillin.我应当让他给我打一针青霉素的。
• Penicillin was an extremely significant medical discovery.青霉素是极其重要的医学发现。

17 defense   

n.防御，保卫；[pl.]防务工事；辩护，答辩

参考例句：

• The accused has the right to defense.被告人有权获得辩护。
• The war has impacted the area with military and defense workers.战争使那个地区挤满了军队和防御工程人员。

18 ram   

(random access memory)随机存取存储器

参考例句：

• 512k RAM is recommended and 640k RAM is preferred.推荐配置为512K内存，640K内存则更佳。

19 vessels   

n.血管( vessel的名词复数 )；船；容器；（具有特殊品质或接受特殊品质的）人

参考例句：

• The river is navigable by vessels of up to 90 tons. 90 吨以下的船只可以从这条河通过。 来自《简明英汉词典》
• All modern vessels of any size are fitted with radar installations. 所有现代化船只都有雷达装置。 来自《现代汉英综合大词典》