【英语语言学习】鼠类的觅药行为

From VOA Learning English, this is Science In The News. I’m Mario Ritter.

 

And I’m Jeri Watson. Today we tell about an experimental way to cure drug dependency in rats. We also tell about a health threat to one third of all adults. We have a report on a gene¹ that controls the ability of the heart to repair itself. And we report on a competition for researchers with expertise² in neurobiology.

 

Drug addiction⁴ might be cured with a simple treatment to awaken⁵ a part of the brain of the addict³ – the person who has grown dependent on the drug. Recently, researchers reported they were able to end drug-seeking behavior in rats addicted⁶ to cocaine⁷. They said they did this with laser light by activating⁸ a part of the animals’ brains known as the prefrontal cortex.

 

Cocaine is used widely as a drug. It comes from a substance, an alkaloid, in the coca plant. For several weeks, the researchers gave the drug to a group of rats. The animals quickly became dependent on cocaine.

 

For four days, the rats received a mild but unpleasant electric shock to a foot when they attempted to get more cocaine.

 

Antonello Bonci is scientific director at the United States National Institute on Drug Abuse. He was involved in the study. He says that after the shocks, 70 percent of the rats stopped looking for more cocaine. But the remaining 30 percent continued to show an addictive⁹ hunger for the drug.

 

The researchers compared nerve-cell firing action in both groups of rats by examining cells from a brain area known as the prefrontal cortex. This area is involved in higher brain activity. This includes the making of decisions, controlling unplanned behavior and unwillingness¹⁰ to change one’s mind.

 

Scientists discovered that the addicted rats had reduced activity in a part of the brain cortex called the prelimbic region. The area showed weakness in the self-control processes needed to resist the drug. So, the scientists developed a plan to increase the animal’s ability to control itself.

 

The first step was to inject the brain area with a harmless virus carrying a protein that responds to light. After several weeks, the scientists placed a very small fiber¹¹ optic device into the prefrontal cortex, and sent light to wake up the sleepy area.

 

Antonello Bonci praised the results.

 

“When we turned on some activity in this prefrontal cortex, we could see that the compulsive cocaine seeking was gone.”

 

He says researchers then turned the process around. The rats that had changed their behavior because of the shocks again became cocaine seekers. This happened because the researchers used the fiberoptic method to reduce neuronal firing in the prefrontal cortex.

 

Dr. Bonci says investigators¹² are now designing human clinical tests for electromagnetic brain stimulation¹³ that is non-invasive. He says they are doing this to increase the hypoactive, or inactive, prefrontal cortex of volunteer drug users.

 

He says the plan is to set up testing in the near future. In those trials, he says, cocaine addicts¹⁴ ideally should lose their interest and need for the drug.

 

The heart is our life force. It pumps blood, carrying oxygen to every organ in the body. As the blood flows through the blood vessels¹⁶, it puts pressure on the vessel¹⁵ walls.

 

That pressure is often measured when you go to see a doctor or a health care worker. Blood pressure readings are often taken with a cuff¹⁷, or restraint, tightened¹⁸ around the upper arm.

 

George Thomas is with the Cleveland Clinic in Ohio.

 

“When you go to the doctor, you may see that the blood pressure is reported as two numbers. So there’s an upper number, which is called a systolic blood pressure, and there’s a lower number that is called a diastolic pressure.”

 

The upper number shows the pressure inside the blood vessels when the heart is pumping. The lower number shows the pressure when the heart rests between beats.

 

Stephen Havas is with the University of Maryland School of Medicine. He says both numbers are important.

 

“Any level above 115 systolic or 75 diastolic increases risk. Each 20 millimeters systolic that you go above that 115, your risk doubles.”

 

Higher numbers are evidence of hypertension, the word that doctors use for high blood pressure. Hypertension is a major cause of heart disease, stroke and death.

 

The World Health Organization recently urged the medical community to strengthen efforts to prevent and control high blood pressure. World Health Organization officials say one-third of people over the age of 25 have the condition. Yet many of them do not know they have it.

 

With high blood pressure, the heart must pump harder. That weakens the heart muscle and can lead to heart attack or heart failure. There is no identifiable cause for 95 percent of those with high blood pressure, but there are clues. With age, blood vessels can become harder. Genetics also has an influence, as does family history.

 

Being overweight can also cause blood pressure to rise. Stephen Havas says so can smoking and eating food that contains a lot of salt.

 

“When I ask people about salt in their diet, they usually say they don’t add salt. That’s a good thing. But, you should also remember that most salt or sodium¹⁹ comes from processed foods.”

 

The human body needs only 150 milligrams of salt a day. But most Americans take in between three thousand and four thousand milligrams a day!

 

“The deaths attributed to excess salt consumption represent a huge toll²⁰ – the equivalent of a jumbo jet with more than 400 adults crashing every day of the year, year after year.”

 

Doctors say a good diet can help control high blood pressure. Losing weight and not smoking also can help to control hypertension. Finally, experts say regular medical visits are the best protection against this silent killer²¹.

 

Researchers say they have identified a gene that controls the ability of the heart to repair itself after a heart attack or other injury. The announcement came from scientists at the University of Texas. They had shown earlier that a newborn mammal could regenerate²² heart cells and repair injuries through cell division. But they found the heart lost that ability as the animal developed.

 

The scientists found that a gene called Meis1 became very active in heart cells soon after birth, when the heart muscles stop dividing. They soon began wondering about Meis1 and its importance.

 

The research team removed Meis1 from the heart of newborn mice. They then showed that the period for regenerating²³ cells was lengthened²⁴. The researchers were also able to re-activate this regenerative process in adult mouse hearts by removing the gene.

 

Hesham Sadek led the University of Texas team. He says Meis1 controls several genes²⁵ that normally stop cell division. He compared this to an on-off switch for making adult heart cells divide.

 

The researchers say the finding could provide a new way to study heart regeneration. In Dr. Sadek’s words, “it could introduce a new era in treatment for heart failure.” Many researchers currently are studying the possible use of stem cells to replace damaged heart cells.

 

A report on the University of Texas study was published in the journal Nature.

 

Eppendorf and the journal Science have begun accepting nominations²⁶ for the 2013 Eppendorf & Science Prize for Neurobiology. The prize is presented each year for research in neurobiology.

 

The competition is open to scientists who are 35 years old or younger. A committee of experts will choose the grand prize winner. All nominations must be received by June 15. The winner will receive 25 thousand dollars.

 

An American scientist won the Eppendorf & Science Prize for Neurobiology last year. Marlene Cohen is an assistant professor in the Department of Neuroscience and the Center for the Neural²⁷ Basis of Cognition at the University of Pittsburgh. She studies how we use visual images to gather information about the world.

 

The Eppendorf award committee praised her work. The committee said it provided a new way to study how our mental activity affects what we observe and how mental processes such as attention are controlled.

 

Marlene Cohen and other researchers trained animals to take a test. The test measured their ability to recognize small changes taking place around them. The animals could see these changes if they examined nearby objects carefully.

 

The researchers studied nerve cells called neurons in the animals. Neurons process and send information through electrical and chemical signals. The researchers noted²⁸ changes in the cells when the animals lost interest in an object. They said that when these changes took place, the animals did not perform well and the effect was huge.

 

As Marlene Cohen noted, “when the animals paid attention to the correct location, they could recognize a change about 75 percent of the time. When their attention wandered, they detected the change less than 10 percent of the time.”

 

Her report was published last year in the journal Science. The magazine’s senior editor, Peter Stern, is leading the committee that will choose the 2013 Eppendorf & Science Prize for Neurobiology. Eppendorf is based in Germany. The company develops and manufactures laboratory equipment.

 

This Science In The News was written by Jerilyn Watson and George Grow and. Our producer was June Simms. I’m Mario Ritter.

 

And I’m Jerilyn Watson. Join us again next week for more news about science in Special English on the Voice of America.

1 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。

2 expertise   

n.专门知识(或技能等)，专长

参考例句：

• We were amazed at his expertise on the ski slopes.他斜坡滑雪的技能使我们赞叹不已。
• You really have the technical expertise in a new breakthrough.让你真正在专业技术上有一个全新的突破。

3 addict   

v.使沉溺；使上瘾；n.沉溺于不良嗜好的人

参考例句：

• He became gambling addict,and lost all his possessions.他习染上了赌博，最终输掉了全部家产。
• He assisted a drug addict to escape from drug but failed firstly.一开始他帮助一个吸毒者戒毒但失败了。

4 addiction   

n.上瘾入迷，嗜好

参考例句：

• He stole money from his parents to feed his addiction.他从父母那儿偷钱以满足自己的嗜好。
• Areas of drug dealing are hellholes of addiction,poverty and murder.贩卖毒品的地区往往是吸毒上瘾、贫困和发生谋杀的地方。

5 awaken   

vi.醒，觉醒；vt.唤醒，使觉醒，唤起，激起

参考例句：

• Old people awaken early in the morning.老年人早晨醒得早。
• Please awaken me at six.请于六点叫醒我。

6 addicted   

adj.沉溺于....的，对...上瘾的

参考例句：

• He was addicted to heroin at the age of 17.他17岁的时候对海洛因上了瘾。
• She's become addicted to love stories.她迷上了爱情小说。

7 cocaine   

n.可卡因，古柯碱（用作局部麻醉剂）

参考例句：

• That young man is a cocaine addict.那个年轻人吸食可卡因成瘾。
• Don't have cocaine abusively.不可滥服古柯碱。

8 activating   

活动的，活性的

参考例句：

• "I didn't say we'd got to stop activating the masses! “我并没说就此不发动！ 来自子夜部分
• Presumably both the very small size and activating influence of fluorine atoms contribute to this exception. 这大概是由于氟原子半径小和活性高这两个原因的影响，氟原子对这种例外做出了贡献。

9 addictive   

adj.(吸毒等)使成瘾的，成为习惯的

参考例句：

• The problem with video game is that they're addictive.电子游戏机的问题在于它们会使人上瘾。
• Cigarettes are highly addictive.香烟很容易使人上瘾。

10 unwillingness   

n. 不愿意，不情愿

参考例句：

• Her unwillingness to answer questions undermined the strength of her position. 她不愿回答问题，这不利于她所处的形势。
• His apparent unwillingness would disappear if we paid him enough. 如果我们付足了钱，他露出的那副不乐意的神情就会消失。

11 fiber   

n.纤维，纤维质

参考例句：

• The basic structural unit of yarn is the fiber.纤维是纱的基本结构单元。
• The material must be free of fiber clumps.这种材料必须无纤维块。

12 investigators   

n.调查者，审查者( investigator的名词复数 )

参考例句：

• This memo could be the smoking gun that investigators have been looking for. 这份备忘录可能是调查人员一直在寻找的证据。
• The team consisted of six investigators and two secretaries. 这个团队由六个调查人员和两个秘书组成。 来自《简明英汉词典》

13 stimulation   

n.刺激，激励，鼓舞

参考例句：

• The playgroup provides plenty of stimulation for the children.幼儿游戏组给孩子很多启发。
• You don't get any intellectual stimulation in this job.你不能从这份工作中获得任何智力启发。

14 addicts   

有…瘾的人( addict的名词复数 )； 入迷的人

参考例句：

• a unit for rehabilitating drug addicts 帮助吸毒者恢复正常生活的机构
• There is counseling to help Internet addicts?even online. 有咨询机构帮助网络沉迷者。 来自超越目标英语 第3册

15 vessel   

n.船舶；容器，器皿；管，导管，血管

参考例句：

• The vessel is fully loaded with cargo for Shanghai.这艘船满载货物驶往上海。
• You should put the water into a vessel.你应该把水装入容器中。

16 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》

17 cuff   

n.袖口；手铐；护腕；vt.用手铐铐；上袖口

参考例句：

• She hoped they wouldn't cuff her hands behind her back.她希望他们不要把她反铐起来。
• Would you please draw together the snag in my cuff?请你把我袖口上的裂口缝上好吗？

18 tightened   

收紧( tighten的过去式和过去分词 )； （使）变紧； （使）绷紧； 加紧

参考例句：

• The rope holding the boat suddenly tightened and broke. 系船的绳子突然绷断了。
• His index finger tightened on the trigger but then relaxed again. 他的食指扣住扳机，然后又松开了。

19 sodium   

n.（化）钠

参考例句：

• Out over the town the sodium lights were lit.在外面，全城的钠光灯都亮了。
• Common salt is a compound of sodium and chlorine.食盐是钠和氯的复合物。

20 toll   

n.过路(桥)费；损失，伤亡人数；v.敲(钟)

参考例句：

• The hailstone took a heavy toll of the crops in our village last night.昨晚那场冰雹损坏了我们村的庄稼。
• The war took a heavy toll of human life.这次战争夺去了许多人的生命。

21 killer   

n.杀人者，杀人犯，杀手，屠杀者

参考例句：

• Heart attacks have become Britain's No.1 killer disease.心脏病已成为英国的头号致命疾病。
• The bulk of the evidence points to him as her killer.大量证据证明是他杀死她的。

22 regenerate   

vt.使恢复，使新生；vi.恢复，再生；adj.恢复的

参考例句：

• Their aim is to regenerate British industry.他们的目的是复兴英国的工业。
• Although it is not easy,you have the power to regenerate your life.尽管这不容易，但你有使生活重获新生的能力。

23 regenerating   

v.新生，再生( regenerate的现在分词 )；正反馈

参考例句：

• It is not proposed to deal with the detailed histology of regenerating tissues here. 这里未提出详细的再生组织的组织学。 来自辞典例句
• This is accomplished by using a thermocompressor to recycle regenerating steam through the absorber. 它用热压机使再生蒸汽经吸附器循环完成解吸过程。 来自辞典例句

24 lengthened   

（时间或空间）延长，伸长( lengthen的过去式和过去分词 )

参考例句：

• The afternoon shadows lengthened. 下午影子渐渐变长了。
• He wanted to have his coat lengthened a bit. 他要把上衣放长一些。

25 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

26 nominations   

n.提名，任命( nomination的名词复数 )

参考例句：

• Nominations are invited for the post of party chairman. 为党主席职位征集候选人。 来自《简明英汉词典》
• Much coverage surrounded his abortive bids for the 1960,1964, and 1968 Republican Presidential nominations. 许多消息报道都围绕着1960年、1964年和1968年他为争取提名为共和党总统候选人所做努力的失败。 来自辞典例句

27 neural   

adj.神经的，神经系统的

参考例句：

• The neural network can preferably solve the non- linear problem.利用神经网络建模可以较好地解决非线性问题。
• The information transmission in neural system depends on neurotransmitters.信息传递的神经途径有赖于神经递质。

28 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。