VOA慢速英语 2007 0502a

This is the VOA Special English Health Report.

Scientists may have found a way to reduce shortages¹ of type O blood. Type O is the kind of blood that hospitals most often need. What the researchers are testing is an easier way to make type O blood out of other kinds of blood. 

Health worker collects freshly donated blood

There are four main blood types. Most people are born with one of these four: type A, type B, type AB or type O.

Type O is known as the universal blood type. It can be safely given to anyone. So it is commonly used when a person is injured or sick and has to have a blood transfusion².

Type O is the most common blood group. But the supplies of it available in hospitals and blood banks are usually limited. This is because of high demand. Type O blood is used in emergencies when there is no time to identify the patient's blood type.

Giving A, B or AB to someone with a different blood type, including O, can cause a bad reaction by the person's defense³ system. Their immune⁴ system can reject the blood. This immune reaction can be deadly. For example, people may die if they receive transplanted⁵ organs from someone with the wrong blood type.

The difference between blood types is related to whether or not red blood cells contain certain kinds of sugar molecules⁶. These molecules are found on the surface of the cells. They are known as antigens. These antigens are found with type A, B and AB blood but not with type O.

More than twenty-five years ago, scientists found that the antigens could be removed to create universal-type cells. They could be removed with chemicals called enzymes⁷. But large amounts of enzymes were required to make the change.

Now, a report published in Nature Biotechnology describes two formerly⁸ unknown bacterial⁹ enzymes. The scientists say these enzymes remove the antigens more easily. To find these enzymes, the researchers examined more than two thousand five hundred kinds of bacteria and fungi¹⁰.

Doctor Henrik Clausen of the University of Copenhagen in Denmark led the study. He worked with researchers from France, Sweden and the United States.

The next step, they say, is to complete safety tests. The team is working with the American company ZymeQuest to test the new method. If it meets safety requirements and is not too costly¹¹, it could become a widely used life-saving tool to increase the supply of universal blood.

And that's the VOA Special English Health Report, written by Brianna Blake. For more health news, go to voaspecialenglish.com. I'm Steve Ember.

1 shortages   

n.不足( shortage的名词复数 )；缺少；缺少量；不足额

参考例句：

• Food shortages often occur in time of war. 在战争期间常常发生粮食短缺的情形。 来自《现代汉英综合大词典》
• At the same time, worldwide food and fuel shortages eased. 同时，世界性粮食和石油短缺的现象终止了。 来自英汉非文学 - 政府文件

2 transfusion   

n.输血，输液

参考例句：

• She soon came to her senses after a blood transfusion.输血后不久她就苏醒了。
• The doctor kept him alive by a blood transfusion.医生靠输血使他仍然活着。

3 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。

4 immune   

adj.免疫的，有免疫力的，不受影响的，免除的

参考例句：

• I am immune from the disease,for I had it once.我对这病有免疫力，因为我已得过一次了。
• Be immune from corruption.拒腐蚀，永不沾。

5 transplanted   

vt.移植（transplant的过去式与过去分词形式）

参考例句：

• Surgeons have successfully transplanted a liver into a four-year-old boy. 外科医生成功地给一个四岁的男孩移植了肝脏。
• A group of farmers were transplanted to the island by the government. 一批农民被政府迁到这个岛上居住。 来自《简明英汉词典》

6 molecules   

分子( molecule的名词复数 )

参考例句：

• The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
• Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。

7 enzymes   

n. 酶，酵素

参考例句：

• It was said that washing powders containing enzymes remove stains more efficiently. 据说加酶洗衣粉除污更有效。
• Among the enzymes which are particularly effective are pepsin, papain. 在酶当中特别有效的是胃朊酶、木瓜酶。

8 formerly   

adv.从前，以前

参考例句：

• We now enjoy these comforts of which formerly we had only heard.我们现在享受到了过去只是听说过的那些舒适条件。
• This boat was formerly used on the rivers of China.这船从前航行在中国内河里。

9 bacterial   

a.细菌的

参考例句：

• Bacterial reproduction is accelerated in weightless space. 在失重的空间，细菌繁殖加快了。
• Brain lesions can be caused by bacterial infections. 大脑损伤可能由细菌感染引起。

10 fungi   

n.真菌，霉菌

参考例句：

• Students practice to apply the study of genetics to multicellular plants and fungi.学生们练习把基因学应用到多细胞植物和真菌中。
• The lawn was covered with fungi.草地上到处都是蘑菇。

11 costly   

adj.昂贵的，价值高的，豪华的

参考例句：

• It must be very costly to keep up a house like this.维修这么一幢房子一定很昂贵。
• This dictionary is very useful,only it is a bit costly.这本词典很有用，左不过贵了些。