文章来源:未知 文章作者:meng 发布时间:2010-05-27 06:14 字体: [ ]  进入论坛

Researchers at Northwestern University Feinberg School of Medicine have identified in mice a previously1 unknown protective mechanism2 by which the smallest blood vessels4(血管) remove blood clots5(血凝块,血栓) and other blockages7 from the brain. The findings provide insights into mechanisms8 that may be involved in age-related cognitive9(认知的,认识的) decline, Alzheimer's disease and recovery from stroke. These findings were described in the May 27 issue of Nature by Jaime Grutzendler, M.D., and colleagues. The study was supported by the National Institute on Aging (NIA), part of the National Institutes of Health.

Uninterrupted blood flow is critical for brain function, and the brain has developed various mechanisms to maintain it. Blockages(堵塞,妨碍) in the smallest blood vessels can be cleared by processes that disintegrate10(破碎,瓦解) or wash them out. However, not all blockages are cleared completely. Persistent11 blockage6 can reduce or stop blood flow, limiting the supply of oxygen and nutrients12 to the surrounding tissue and nerve cells. This, in turn, can lead to impaired13(受损的) communications between nerve cells and ultimately cell death.

The researchers used a newly developed imaging technique that can view the smallest blood vessels, known as microvessels(微脉管) , in the brains of living mice. They found that two to seven days after a blockage in brain microvessels, the cells lining14 the blood vessel3 wall engulf15(吞没) the remaining portion of the blockage, encapsulate(压缩,封装) it, seal it off from the interior of the blood vessel and finally expel the blocking material outside of the vessel. As a result of this process, blood flow is restored to the affected16 area.

"These are intriguing17(米人的,有趣的) findings," said NIA Director Richard J. Hodes, M.D. "They open new avenues of basic research that may increase our understanding of how microvessels are maintained in the brain and throughout the body."

The research team demonstrated that this complex protective mechanism involves the activity of an enzyme18(酶) , matrix metalloprotease 2/9, which breaks down large proteins and is known to play a role in blood vessel development and in stroke.

The researchers also found that the ability to move the blockage out of the blood vessel diminished(减少,削弱) with age. Young mice (age 4 months) were able to clear blockages more quickly and thoroughly19 than older mice (age 22 months). The incomplete removal of blockages in the brains of older mice led to a prolonged(延长的,拖延的) shortage of oxygen to the surrounding nerve cells and damaged the connections between nerve cells in the vicinity of(在……附近) the obstructed20 blood vessels.

"The reduced efficiency of this protective mechanism in the older brain and its effect on the function of nerve cells in the brain may significantly contribute to age-related cognitive decline," said Suzana Petanceska, Ph.D., of the Neurobiology of Aging Branch in NIA's Division of Neuroscience, which funded the research. "This may also be part of the mechanism by which vascular21(血管的) risk factors such as high blood pressure and diabetes22(糖尿病) increase the risk of Alzheimer's disease with age."


1 previously bkzzzC     
  • The bicycle tyre blew out at a previously damaged point.自行车胎在以前损坏过的地方又爆开了。
  • Let me digress for a moment and explain what had happened previously.让我岔开一会儿,解释原先发生了什么。
2 mechanism zCWxr     
  • The bones and muscles are parts of the mechanism of the body.骨骼和肌肉是人体的组成部件。
  • The mechanism of the machine is very complicated.这台机器的结构是非常复杂的。
3 vessel 4L1zi     
  • 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。
4 vessels fc9307c2593b522954eadb3ee6c57480     
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
  • 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》
5 clots fc228b79d0fbd8618ecc4cda442af0dd     
n.凝块( clot的名词复数 );血块;蠢人;傻瓜v.凝固( clot的第三人称单数 )
  • When you cut yourself, blood clots and forms a scab. 你割破了,血会凝固、结痂。 来自《简明英汉词典》
  • Milk clots when it turns sour. 奶变酸就凝块。 来自《现代英汉综合大词典》
6 blockage XRxyc     
  • The logical treatment is to remove this blockage.合理的治疗方法就是清除堵塞物。
  • If the blockage worked,they could retreat with dignity.如果封锁发生作用,他们可以体面地撤退。
7 blockages 7a8ce9c923a54dedf91f0485f41f78a8     
n.堵塞物( blockage的名词复数 );堵塞,阻塞
  • The storms could increase the risks posed by river blockages. 暴风雨会增加因河道堵塞所造成的危险。 来自互联网
  • An angiogram shows the location and severity of blockages in blood vessels. 冠状动脉造影能够显示血管内的阻塞位置以及阻塞的严重程度。 来自互联网
8 mechanisms d0db71d70348ef1c49f05f59097917b8     
n.机械( mechanism的名词复数 );机械装置;[生物学] 机制;机械作用
  • The research will provide direct insight into molecular mechanisms. 这项研究将使人能够直接地了解分子的机理。 来自《简明英汉词典》
  • He explained how the two mechanisms worked. 他解释这两台机械装置是如何工作的。 来自《简明英汉词典》
9 cognitive Uqwz0     
  • As children grow older,their cognitive processes become sharper.孩子们越长越大,他们的认知过程变得更为敏锐。
  • The cognitive psychologist is like the tinker who wants to know how a clock works.认知心理学者倒很像一个需要通晓钟表如何运转的钟表修理匠。
10 disintegrate ftmxi     
  • The older strata gradually disintegrate.较老的岩层渐渐风化。
  • The plane would probably disintegrate at that high speed.飞机以那么高速飞行也许会四分五裂。
11 persistent BSUzg     
  • Albert had a persistent headache that lasted for three days.艾伯特连续头痛了三天。
  • She felt embarrassed by his persistent attentions.他不时地向她大献殷勤,使她很难为情。
12 nutrients 6a1e1ed248a3ac49744c39cc962fb607     
n.(食品或化学品)营养物,营养品( nutrient的名词复数 )
  • a lack of essential nutrients 基本营养的缺乏
  • Nutrients are absorbed into the bloodstream. 营养素被吸收进血液。 来自《简明英汉词典》
13 impaired sqtzdr     
adj.受损的;出毛病的;有(身体或智力)缺陷的v.损害,削弱( impair的过去式和过去分词 )
  • Much reading has impaired his vision. 大量读书损害了他的视力。 来自《现代汉英综合大词典》
  • His hearing is somewhat impaired. 他的听觉已受到一定程度的损害。 来自《现代汉英综合大词典》
14 lining kpgzTO     
  • The lining of my coat is torn.我的外套衬里破了。
  • Moss makes an attractive lining to wire baskets.用苔藓垫在铁丝篮里很漂亮。
15 engulf GPgzD     
  • Floodwaters engulf a housing project in the Bajo Yuna community in central Dominican Republic.洪水吞没了多米尼加中部巴杰优那社区的一处在建的住房工程项目。
  • If we are not strong enough to cover all the minds up,then they will engulf us,and we are in danger.如果我们不够坚强来抵挡大众的意念,就会有被他们吞没的危险。
16 affected TzUzg0     
  • She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
  • His manners are affected.他的态度不自然。
17 intriguing vqyzM1     
  • These discoveries raise intriguing questions. 这些发现带来了非常有趣的问题。
  • It all sounds very intriguing. 这些听起来都很有趣。 来自《简明英汉词典》
18 enzyme cPozF     
  • Above a certain temperature,the enzyme molecule will become unfolded.超过一定温度,酶分子将会展开。
  • An enzyme that dissolves the fibrin of blood clots.能溶解血凝块中的纤维的酶。
19 thoroughly sgmz0J     
  • The soil must be thoroughly turned over before planting.一定要先把土地深翻一遍再下种。
  • The soldiers have been thoroughly instructed in the care of their weapons.士兵们都系统地接受过保护武器的训练。
20 obstructed 5b709055bfd182f94d70e3e16debb3a4     
阻塞( obstruct的过去式和过去分词 ); 堵塞; 阻碍; 阻止
  • Tall trees obstructed his view of the road. 有大树挡着,他看不到道路。
  • The Irish and Bristol Channels were closed or grievously obstructed. 爱尔兰海峡和布里斯托尔海峡或遭受封锁,或受到了严重阻碍。
21 vascular cidw6     
  • The mechanism of this anomalous vascular response is unknown.此种不规则的血管反应的机制尚不清楚。
  • The vascular changes interfere with diffusion of nutrients from plasma into adjacent perivascular tissue and cells.这些血管变化干扰了营养物质从血浆中向血管周围邻接的组织和细胞扩散。
22 diabetes uPnzu     
  • 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。
TAG标签: cells brain blood nerve vessels