SCIENCE IN THE NEWS - Progress Made in Stem Cell Research

SCIENCE IN THE NEWS - Progress Made in Stem Cell Research
By Caty Weaver¹, Jerilyn Watson, ...

Broadcast: Tuesday, May 31, 2005

(MUSIC)

VOICE ONE:

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

VOICE TWO:

And I'm Bob Doughty². On our program this week, we talk about a way to help lung cancer patients. We also report on a treatment that may return sight to damaged eyes.

VOICE ONE:

But first, we tell about a method to produce stem cells that could be used for disease research.

(MUSIC)

VOICE ONE:

Scientists in South Korea have reported major progress in their efforts to copy human embryos⁴. The scientists say they have used the method to produce embryonic⁵ stem cells. Stem cells have the ability to grow into other cells, such as heart, nerve or brain cells. So they might offer new ways to treat injury and disease.

The Korean scientists say their recent work resulted in eleven stem cell groups or lines. Each stem cell line is an exact genetic⁷ copy of a human patient involved in the experiments.

VOICE TWO:

 
Seoul National University professor Hwang Woo-suk
Hwang Woo-suk and Moon Shin-yong led the research effort at Seoul National University. Maybe you recognize those names. We reported on the two men last year. At that time, they were the first scientists to report success in producing a stem cell line from a human embryo³ they had copied, or cloned.

Cloning is reproduction by one parent in which an exact genetic copy is created. A similar process happens in nature. It is called asexual reproduction.

In the laboratory, such a process begins with egg cells. Scientists remove the nucleus⁸ from each cell. The nucleus contains the complete genetic plan for an organism. The last step is to place the nucleus of an adult cell into the egg.

VOICE ONE:

The South Korean study last year involved eggs from sixteen women. The same women also provided the adult cells to be placed into each of their eggs.

Recently, the scientists used eggs from eighteen women. But, the skin cells they placed into the eggs came from eleven other people. Nine of them have spinal⁹ cord injuries. Another has the disease diabetes¹⁰. And the eleventh has a genetic disorder¹¹. The group included men, women and a child as young as two years old.

VOICE TWO:

The scientists developed new methods for their experiments. For example, this time they did not use a needle to pull the nucleus from the egg.

 
 
Instead, they reportedly made a small cut in the egg and pressed the genetic material out through the opening. They used the same hole to place the skin cell into the egg.

The result was eleven stem cell lines from the nine of the people who provided skin cells. Scientists have never before produced stem cells that are genetic copies of people with diseases or injuries. Scientists hope stem cells will be helpful in the treatment of diseases and injuries because they can grow into any kind of cell.

VOICE ONE:

Gerald Schatten is a reproductive biologist at the University of Pittsburgh. He advised the Korean scientists and helped to prepare the English language version of their report. He says the study brings science much closer to use of stem cells in medical treatments. He says the scientists showed that stems cell lines can be established through the use of people of different ages, sexes and health conditions.

Not everyone is as happy about the study. There are many political and moral questions about experiments involving cloning. Lawmakers in many areas are not sure how to supervise such science.

Last week, the United States House of Representatives passed a bill that would ease restrictions¹² on government aid for embryonic stem cell research. President Bush has threatened to veto the bill. He says an embryo is human life and should not be destroyed.

VOICE TWO:

Some people have expressed fear that cloning could one day be used to produce babies. Some scientists have already created animals this way. But, most scientists, politicians and clergy¹³ say the idea of reproductive cloning of humans is un-acceptable.

Doctor Hwang says the goal of his experiments is limited to finding cures for disease and injury. He says it must continue for this reason only. He says his team has no plan of using the new method for making babies.

(MUSIC)

VOICE ONE:

An American research center has reported studies that may some day help return sight to damaged eyes. Scientists at the Schepens Eye Research Institute say they have repaired a damaged optic nerve connection in mice.

Dong Feng Chen reported on the study. She teaches at Harvard Medical School in the state of Massachusetts. The study was published in the magazine, Journal of Cell Science.

The optic nerve connection links the eye to the brain. It makes sight possible. The optic nerve contains millions of nerve cells. When healthy, the cells carry sight messages from the eye to the brain. The brain makes it possible for a person or animal to see the image sent by the eye.

The eye and the optic nerve are part of the central nervous system. Many body parts are able to repair themselves after injury. But this is not true for nerve cells in the central nervous system.

VOICE TWO:

Doctor Chen and her team want to know why tissue from the central nervous system stops repairing itself. A scientist in Doctor Chen's laboratory tested two ways to re-start the process in the optic nerve. One way involved a gene⁶ called BCL-two. BCL-two normally is not active. The scientists thought this lack of activity was blocking nerve restoration. So they developed a mouse in which the gene is always active.

The scientists also believed scar tissue on the brain helped stop a damaged nerve from repairing itself. The scar was created from a healed wound soon after birth. Specialized¹⁴ cells called glial cells create the scar.

VOICE ONE:

The scientists found that the animals with the active BCL-two gene could quickly repair damaged optic-nerve tissue. But this could happen only when the mice were very young. It could happen only before their glial scars developed. Then the scientists carried out another experiment with mice. They again used animals with active BCL-two genes¹⁵. But they added a process to the experiment. They reduced the ability to develop a glial scar in these mice. The optic nerves were restored in the mice, even when they were older.

Doctor Chen said the scientists observed that at least forty percent of the optic nerve in the animals had been repaired. But she said a higher percentage probably was repaired than they could observe. They will now attempt to learn if the restored nerves can operate like undamaged nerves. Doctor Chen says she believes their methods might repair optic nerves and other tissue of the nervous system.

(MUSIC)

VOICE TWO:

A new study suggests that sunlight and vitamin D may help some people with lung cancer live longer. Lung cancer is the most common cancer around the world, with more than one million new cases each year. It kills more people than any other cancer. About sixty percent of those who get lung cancer die within a year. The major preventable cause is the use of tobacco.

Vitamin D helps build strong teeth and bones. Foods such as oily fish and egg yolks are high in vitamin D. But not many foods naturally have high amounts of the vitamin. So extra vitamin D is often added to milk products. Some people take vitamin D pills. Another way to get vitamin D is from sunshine. The body produces it through the skin from the ultraviolet radiation of the sun.

VOICE ONE:

Scientists from Harvard University led a study of more than four hundred fifty people. These men and women had been treated for lung cancer in Massachusetts. Doctors operated to remove their tumors.

Scientists asked the people what they ate, what vitamins they took and what time of year their operations had taken place. Some took high levels of vitamin D and had their operations during the summer, when there is lots of sunshine. Others had low levels of the vitamin, and were operated on in winter.

VOICE TWO:

The scientists found that thirty percent of the people in this second group were alive five years after their operation. Forty-six percent were disease-free. But patients with the highest vitamin D intake¹⁶ and summer operations had higher survival rates. Seventy-two percent were still alive after five years. And eighty-three percent were disease-free.

The findings were presented at a meeting of the American Association for Cancer Research. Other studies are needed to confirm them.

(MUSIC)

VOICE ONE:

This program was written by Cynthia Kirk, Jerilyn Watson and Caty Weaver. Cynthia Kirk was our producer. I'm Barbara Klein.

VOICE ONE:

And I'm Bob Doughty. Join us again next week for SCIENCE IN THE NEWS, in VOA Special English.

(MUSIC)

1 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。

2 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。

3 embryo   

n.胚胎，萌芽的事物

参考例句：

• They are engaging in an embryo research.他们正在进行一项胚胎研究。
• The project was barely in embryo.该计划只是个雏形。

4 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

5 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。

6 gene   

n.遗传因子，基因

参考例句：

• A single gene may have many effects.单一基因可能具有很多种效应。
• The targeting of gene therapy has been paid close attention.其中基因治疗的靶向性是值得密切关注的问题之一。

7 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。

8 nucleus   

n.核，核心，原子核

参考例句：

• These young people formed the nucleus of the club.这些年轻人成了俱乐部的核心。
• These councils would form the nucleus of a future regime.这些委员会将成为一个未来政权的核心。

9 spinal   

adj.针的，尖刺的，尖刺状突起的；adj.脊骨的，脊髓的

参考例句：

• After three days in Japan,the spinal column becomes extraordinarily flexible.在日本三天，就已经使脊椎骨变得富有弹性了。
• Your spinal column is made up of 24 movable vertebrae.你的脊柱由24个活动的脊椎骨构成。

10 diabetes   

n.糖尿病

参考例句：

• In case of diabetes, physicians advise against the use of sugar.对于糖尿病患者，医生告诫他们不要吃糖。
• Diabetes is caused by a fault in the insulin production of the body.糖尿病是由体內胰岛素分泌失调引起的。

11 disorder   

n.紊乱，混乱；骚动，骚乱；疾病，失调

参考例句：

• When returning back,he discovered the room to be in disorder.回家后，他发现屋子里乱七八糟。
• It contained a vast number of letters in great disorder.里面七零八落地装着许多信件。

12 restrictions   

约束( restriction的名词复数 )； 管制； 制约因素； 带限制性的条件（或规则）

参考例句：

• I found the restrictions irksome. 我对那些限制感到很烦。
• a snaggle of restrictions 杂乱无章的种种限制

13 clergy   

n.[总称]牧师，神职人员

参考例句：

• I could heartily wish that more of our country clergy would follow this example.我衷心希望，我国有更多的牧师效法这个榜样。
• All the local clergy attended the ceremony.当地所有的牧师出席了仪式。

14 specialized   

adj.专门的，专业化的

参考例句：

• There are many specialized agencies in the United Nations.联合国有许多专门机构。
• These tools are very specialized.这些是专用工具。

15 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

16 intake   

n.吸入，纳入；进气口，入口

参考例句：

• Reduce your salt intake.减少盐的摄入量。
• There was a horrified intake of breath from every child.所有的孩子都害怕地倒抽了一口凉气。