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健康新发现:医学新测试 更快的判断肺结核的类型

kira86 于2009-03-25发布 l 已有人浏览
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New Test Could Speed Tuberculosis Results This is the VOA Special English Health Report.Tuberculosis killed on
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New Test Could Speed Tuberculosis Results




This is the VOA Special English Health Report.

Tuberculosis killed one million three hundred thousand people around the world in two thousand seven. In addition, almost half a million people who were infected with tuberculosis and with H.I.V. also died. Those were listed as H.I.V. deaths.

An estimated one-third of all people are infected with tuberculosis. But the body's natural defenses are usually strong enough to prevent an active case. Even so, the bacteria remain in the body. If the immune system weakens at any point, they begin to spread and then attack.

The bacteria that cause TB usually settle in the lungs. They spread through the air when the person coughs or sneezes or even sings and talks.

One of the most important things is to identify cases quickly -- especially drug-resistant cases, which are increasing. The patients need to be kept away from other people and begin treatment as soon as possible.

Multidrug resistant tuberculosis, or MDR-TB, will not get better with antibiotics normally used for tuberculosis. So doctors must use stronger, "second line" drugs when the first ones fail. Extensively drug-resistant tuberculosis, or XDR-TB, will not respond to any of those drugs but might still be treatable.

Now, researchers say they have found a much faster way to identify drug-resistant TB. The study's lead author is Graham Hatfull at the University of Pittsburgh in Pennsylvania. He says current tests can sometimes take weeks in rural and poor areas of the world. By that time, the patient may already be dead.

The scientists used viruses called bacteriophages to speed the process. These viruses attack bacteria. The researchers injected them with a gene that produces a green glow of light. They also injected some with first line antibiotics and others with second line drugs.

Then they combined the bacteriophages with TB bacteria. If the bacteria glow, it means they are drug resistant. The researchers say a clinic worker could identify the glow with equipment available in many clinics. Test results would not have to wait for the bacteria to grow in a laboratory far away.

For now, the test itself needs more testing. But Professor Hatfull is hopeful this will take months and not years.

Researchers from the Albert Einstein College of Medicine in New York also took part in the study, financed by the Howard Hughes Medical Institute. The findings appear in the journal PLoS ONE, published by the Public Library of Science.

And that's the VOA Special English Health Report, written by Caty Weaver. I'm Steve Ember.

结核病的类型
  
 结核病分原发和继发性,初染时多为原发(Ⅰ型);而原发性感染后遗留的病兆,在人抵抗力下降时,可能重新感染,通过血循环播散或直接蔓延而致继发感染(Ⅱ型~Ⅳ型)。
  
(1)原发性肺结核(Ⅰ型):常见于小儿,多无症状,有时表现为低热、轻咳、出汗、心跳快、食欲差等;少数有呼吸音减弱,偶可闻及干性或湿性罗音。
  
(2)血行播散型肺结核(Ⅱ型):急性粟粒型肺结核起病急剧,有寒战、高热,体温可达40℃以上,多呈弛张热或稽留热,血白细胞可减少,血沉加速。亚急性与慢性血行播散性肺结核病程较缓慢。
  
(3)浸润型肺结核(Ⅲ型):肺部有渗出、浸润及不同程度的干酷样病变。多数发病缓慢,早期无明显症状,后渐出现发热、咳嗽、盗汗、胸痛、消瘦、咳痰及咯血。血常规检查可见血沉增快,痰结核菌培养为阳性。
  (4)慢性纤维空洞型肺结核(Ⅳ型):反复出现发热、咳嗽、咯血、胸痛、盗汗、食欲减退等,胸廓变形,病侧胸廓下陷,肋间隙变窄,
呼吸运动受限,气管向患侧移位,呼吸减弱。血常规检查可见血沉值增快,痰结核菌培养为阳性,X线显示空洞、纤维化、支气管播散三大特征。

病因和发病机理:
  
一、结核菌
  
属于分支杆菌,涂片染色具有抗酸性,亦称抗酸杆菌。对外抵抗力强,在阴湿处能生存5个小时有以上,但在烈日曝晒下2小时,5-12%来苏水接触2-12小时,70%酒精接触2分钟,或煮沸1分钟,能被杀死。而最简单的杀菌方法是将痰吐在纸上直接烧掉。
  
二、感染途径
  
结核菌主要通过呼吸道传播。传染源主要是排菌的肺结核病人的痰。传染的次要途径是经消化道进入体内,此外还可经皮肤传播。
  
三、人体的反应性
  
结核病的免疫主要是细胞免疫,表现在淋巴细胞的致敏和细胞吞噬作用的增强。入侵的结核菌被吞噬后,经处理加工,将抗原信息传递给T淋巴细胞,使之致敏。当致敏的T淋巴细胞再次遇到结核菌时,便释放出一系列的淋巴。因子使巨噬细胞聚集在细菌周围,吞噬杀死细菌,然后变为类上皮细胞和郎罕巨细胞,最后形成结核结节。
  
病理:结核菌侵入人体后引起炎症反应,细菌与人体抵抗力之间的较量互有消长,病变过程复杂,但其基本病变主要有渗出、增生、变质。

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