VOA慢速英语2013 Researchers Hunt for Clues about Parkinson’s Disease

 

Researchers Hunt for Clues about Parkinson’s Disease

This is SCIENCE IN THE NEWS, in VOA Special English. I’m Faith Lapidus.

And I’m Bob Doughty¹. Today we tell about Parkinson’s disease. We also report on treatments for the disease.

Parkinson’s is a disease of the central nervous system. It is a progressive disorder², meaning it gets worse over time. The disease affects a small area of cells in the middle of the brain. This area is called the substantia nigra. The cells slowly lose their ability to produce a chemical called dopamine.

The decrease in the amount of dopamine can result in one or more general symptoms of Parkinson’s disease. These include shaking of the hands, arms and legs. Other signs can include difficulty moving or keeping balanced while walking or standing⁴. There might be emotional changes, like feeling depressed⁵ or worried. The symptoms of Parkinson's differ from person to person. They also differ in their intensity⁶.

The disease is named after James Parkinson. He was a British doctor who first described this condition in 1817. During the 1960s, researchers discovered changes in the brains of people with Parkinson’s. These discoveries led to medicines to treat the effects of the disease. There is no cure for Parkinson's and no way to prevent it. And doctors still are not sure what causes the disease.

America’s National Institutes of Health says at least 500 thousand people in the United States have Parkinson’s disease. About 50 thousand new cases are reported each year. That number is expected to grow as the average age of the population increases.

Parkinson’s often affects people around the age of 60. Some researchers believe that almost everyone would develop Parkinson’s eventually if they lived long enough.

Most patients have what is called idiopathic Parkinson’s disease. Idiopathic means the cause is unknown. People who develop the disease often want to link it to something they can identify. This might be a medical operation or extreme emotional tension.

Many doctors reject this idea of a direct link to Parkinson’s. They point to people who have similar experiences and do not develop the disease.

There are several theories about the cause of Parkinson’s, but none have been confirmed. Studies have shown a link between the disease and some chemical products. In early 2013, a United Nations study found that man-made chemicals in everyday products are to blame. Other researchers say the disease could result from having contact with chemical pesticides⁸, like those used for killing⁹ insects.

Scientists say it is difficult to show a direct link between diseases like Parkinson’s and the environment. But in 2007, a European study found a link between Parkinson’s and pesticide⁷ use. The study also showed that serious head injuries increased a person's risk of the disease.

Scientists at Aberdeen University in Scotland collected information about more than 900 people with Parkinson's or similar conditions. They compared this group to almost two thousand people without the disorder. All the people were asked about their use of pesticides, chemical fluids and metals like iron. The researchers also collected information about family history of the disease and head injuries.

Farm workers and people who said they often used pesticides had a 41 percent greater risk of Parkinson's than others. The disease was also two and one-half times more common among people who had been knocked unconscious more than once in their lives. These people temporarily lost consciousness after suffering a blow to the head.

Another area of study is family genetics. There are examples of members of a family having Parkinson’s disease. The National Institutes of Health says about 15 percent of Parkinson’s patients are related to others with the disease.

About 10 percent of Parkinson’s cases are said to result from genetic¹⁰ mutations, changes within specific genes¹². One such mutation¹¹ is called parkin. Recently, German scientists reported finding what they call a signal transduction pathway that activates¹³ the parkin gene³. They said it also prevents stress-induced death of dopamine-producing neuron cells.

American scientists reported finding how the most common genetic mutations in familial Parkinson’s damage brain cells. They said these mutations prevent an intracellular system from operating normally. This system prevents a protein called alpha-synuclein from reaching harmful levels in dopamine-producing neurons.

The report came from researchers at the Columbia University School of Medicine and the Albert Einstein College of Medicine of Yeshiva University in New York. Their findings were published in the journal Nature Neuroscience.

There is no cure for Parkinson’s disease. But improved treatments to ease the effects of the disease make it possible for many patients to live almost normal lives. People who have lost their ability to do many things sometimes are able to regain¹⁴ some of these abilities with treatment.

The most commonly used drug is levodopa combined with carbidopa. The National Institutes of Health says levodopa is a chemical found naturally in plants and animals. When it reaches the brain, levodopa is changed into dopamine, the chemical that is lacking in people with the disease. Carbidopa delays the change in levodopa until after it reaches the brain.

Levodopa helps ease symptoms of Parkinson's. But it does not prevent more changes in the brain that are caused by the disease. Other drugs used to treat Parkinson’s disease act like dopamine. They produce reactions in the nerve cells in the brain. They can be given alone or in combination with levodopa. Many of the possible side effects are similar to those linked with the use of levodopa. They include sleepiness, feeling sick or having bad dreams.

An operation called deep-brain stimulation¹⁵ also is used to treat Parkinson’s disease. Doctors use this treatment to shock the brain in areas that help send messages to the body. These areas can become blocked in Parkinson’s patients. When this happens, the messages give misinformation to the body.

In deep brain stimulation, doctors make two small holes in the patient’s head. Next, two thin, electrical wires are then placed in the brain. They are connected under the skin to another wire that leads to a small battery placed in the chest. The device supplies electricity.

Deep brain stimulation can reduce the need for levodopa and other drugs. It also helps to reduce symptoms such as shaking and slowness of movement. But brain stimulation has been shown to have more side effects than drug treatments. In one study, about 40 percent of the patients who had the operation experienced problems, including infection.

Deep brain stimulation is not the answer for all Parkinson's patients. Doctors say it is best for patients whose medicines cause side effects or are not working. The treatment is not new. It was first approved for use in the United States in 1997.

Some American researchers think they have found a way to slow the progression of Parkinson’s disease. Scientists at Northwestern University looked at the brain cells that were most at risk of getting the disease.

The cells reportedly permitted lots of calcium¹⁶ to enter their cell bodies. The calcium killed dopamine-producing cells and led to signs of Parkinson’s disease. The scientists say they found a drug that limited the ability of the brain cells to take in calcium, without causing harmful side effects. More tests are planned.

Scientists are also exploring experimental treatments. Since taking office, President Obama ended restrictions¹⁷ on the use of federal money for studies of human embryonic¹⁸ stem cells. Stem cells from very early embryos¹⁹ are able to grow into any tissue in the body.

Scientists say such cells might be able to cure or treat diseases like Parkinson’s. But opponents say stem cell experiments are wrong because human embryos are destroyed. They say this is just like destroying a human life. 

1 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。

2 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。

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 standing   

n.持续，地位；adj.永久的，不动的，直立的，不流动的

参考例句：

• After the earthquake only a few houses were left standing.地震过后只有几幢房屋还立着。
• They're standing out against any change in the law.他们坚决反对对法律做任何修改。

5 depressed   

adj.沮丧的，抑郁的，不景气的，萧条的

参考例句：

• When he was depressed,he felt utterly divorced from reality.他心情沮丧时就感到完全脱离了现实。
• His mother was depressed by the sad news.这个坏消息使他的母亲意志消沉。

6 intensity   

n.强烈，剧烈；强度；烈度

参考例句：

• I didn't realize the intensity of people's feelings on this issue.我没有意识到这一问题能引起群情激奋。
• The strike is growing in intensity.罢工日益加剧。

7 pesticide   

n.杀虫剂，农药

参考例句：

• The pesticide was spread over the vegetable plot.菜田里撒上了农药。
• This pesticide is diluted with water and applied directly to the fields.这种杀虫剂用水稀释后直接施用在田里。

8 pesticides   

n.杀虫剂( pesticide的名词复数 )；除害药物

参考例句：

• vegetables grown without the use of pesticides 未用杀虫剂种植的蔬菜
• There is a lot of concern over the amount of herbicides and pesticides used in farming. 人们对农业上灭草剂和杀虫剂的用量非常担忧。 来自《简明英汉词典》

9 killing   

n.巨额利润；突然赚大钱，发大财

参考例句：

• Investors are set to make a killing from the sell-off.投资者准备清仓以便大赚一笔。
• Last week my brother made a killing on Wall Street.上个周我兄弟在华尔街赚了一大笔。

10 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。

11 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。

12 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

13 activates   

使活动，起动，触发( activate的第三人称单数 )

参考例句：

• Activates the window and displays it in its current size and position. 激活窗口，保持当前的大小及位置不变。
• Pulling out the alarm switch activates alarm and pushing it deactivates it. 闹钟的开和关是通过拔出和按入闹铃开关实现的。

14 regain   

vt.重新获得，收复，恢复

参考例句：

• He is making a bid to regain his World No.1 ranking.他正为重登世界排名第一位而努力。
• The government is desperate to regain credibility with the public.政府急于重新获取公众的信任。

15 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。

16 calcium   

n.钙(化学符号Ca)

参考例句：

• We need calcium to make bones.我们需要钙来壮骨。
• Calcium is found most abundantly in milk.奶含钙最丰富。

17 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

18 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。

19 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