英语听力文摘 English Digest 565、什么是儿童早衰症？

 　　What Is Progeria?

 

　　Progeria was first described in the nineteenth century. The mysterious disease is often thought of as premature¹ aging.

 

　　Children with progeria are normal for their first year of life, but then develop medical problems normally seen in the elderly.

 

　　Their bones weaken. Their skin wrinkles. They lose their hair. They die from heart attacks or strokes brought on by hardened arteries² and high blood pressure. None lives past their early teens.

 

　　In 2003, researchers discovered what causes progeria: a genetic⁴ point mutation⁵. That means that when genes⁶ are being copied to make egg or sperm⁷, just one position in one DNA⁸ strand⁹ is copied wrong. It is like copying a pancake recipe and replacing baking powder with salt. The pancake is not going to rise.

 

　　For children with progeria, the gene³ that encodes lamin A, a protein in the cell’s nucleus¹⁰, is faulty. When the lamin A protein is normally made, a chemical piece called farnesyl is lopped off. In the progeria cell, the farnesyl stays attached. The mutant protein remains¹¹ sticky and piles up in the nucleus, altering the cell’s function.

 

　　Progeria research is moving in two complementary directions. Some scientists are working to find treatments for the disease with anti cancer, cholesterol¹² lowering, bone strengthening, and immune suppressing drugs. Others are interested in progeria’s similarity to aging.

 

　　Progeria like changes have been found in unaffected older people’s skin cells. A protein called prelamin A, which is similar to the mutant protein, increases at low levels and may contribute to hardening of the arteries and other problems that come with aging.

 

　　Though progeria is extremely rare, it may in fact hold the key to aging in all individuals.

 

　　什么是儿童早衰症？

 

　　最早记载的儿童早衰症发生在19世纪。人们通常认为这种神秘的疾病是过早衰老。

 

　　患有早衰症的儿童一岁之前都非常正常，但之后他们会患上通常老年人才会罹患的疾病。

 

　　他们的骨骼变得脆弱，皮肤变得松弛，头发脱落。他们会死于由动脉硬化以及高血压引发的心脏病或中风。没有患者能够活过少年早期。

 

　　2003年，研究者发现了少年早衰症的病因：基因点突变。这表示当基因复制形成卵细胞和精子时，DNA单链上的某处的复制出现错误。这就好像你照着食谱做煎饼，却把盐错当发酵粉用。煎饼当然发不起来。

 

　　患有早衰症的儿童体内编译核纤层蛋白A（细胞核内的一种蛋白质）的基因出现了错误。当核纤层蛋白A被正常编译时，人体内一种名叫法呢基的化学物质会从细胞 核内脱落。而在早衰细胞中，这种化学物质仍然附着在细胞核上。发生突变的蛋白质黏着、堆积在细胞核内，从而影响了细胞的功能。

 

　　对儿童早衰症的研究已经开始往两个互补的方向发展。一些科学家通过对抗癌药、降脂药、健骨药、免疫抑制药的研究，努力寻找治疗该疾病的方法。另一些科学家则对早衰症与自然老化的相似性很感兴趣。

 

　　科学家发现，在一些未患早衰症的老年人的皮肤细胞中也出现了类似早衰症的变化。在这些细胞内，一种叫做前层细胞A的蛋白质与发生突变的蛋白质相似，其数量以较慢的速度增加。这种蛋白可能会导致骨骼脆弱以及其他老化所带来的问题。

1 premature   

adj.比预期时间早的；不成熟的，仓促的

参考例句：

• It is yet premature to predict the possible outcome of the dialogue.预言这次对话可能有什么结果为时尚早。
• The premature baby is doing well.那个早产的婴儿很健康。

2 arteries   

n.动脉( artery的名词复数 )；干线，要道

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。 来自《简明英汉词典》
• This is the place where the three main arteries of West London traffic met. 这就是伦敦西部三条主要交通干线的交汇处。 来自《简明英汉词典》

3 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。

4 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。

5 mutation   

n.变化，变异，转变

参考例句：

• People who have this mutation need less sleep than others.有这种突变的人需要的睡眠比其他人少。
• So far the discussion has centered entirely around mutation in the strict sense.到目前为止，严格来讲，讨论完全集中于围绕突变问题上。

6 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

7 sperm   

n.精子，精液

参考例句：

• Only one sperm fertilises an egg.只有一个精子使卵子受精。
• In human reproduction,one female egg is usually fertilized by one sperm.在人体生殖过程中，一个精子使一个卵子受精。

8 DNA   

(缩)deoxyribonucleic acid 脱氧核糖核酸

参考例句：

• DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
• Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。

9 strand   

vt.使（船）搁浅，使（某人）困于（某地）

参考例句：

• She tucked a loose strand of hair behind her ears.她把一缕散发夹到了耳后。
• The climbers had been stranded by a storm.登山者被暴风雨困住了。

10 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。

11 remains   

n.剩余物，残留物；遗体，遗迹

参考例句：

• He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
• The remains of the meal were fed to the dog.残羹剩饭喂狗了。

12 cholesterol   

n.（U）胆固醇

参考例句：

• There is cholesterol in the cell of body.人体细胞里有胆固醇。
• They are determining the serum-protein and cholesterol levels.他们正在测定血清蛋白和胆固醇的浓度。