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【medical-news】科学家挑战艾滋病痴呆症
Scientists battle HIV dementia
Doctors can't predict which patients will suffer from 'neuroAIDS'
By Lauran Neergaard
Associated Press
WASHINGTON -- It's an Achilles' heel of HIV therapy: The AIDS virus can sneak into the brain to cause dementia despite today's best medicines.
Scientists are beginning to test drugs that may protect against the memory loss and other symptoms of so-called neuroAIDS, which afflicts at least one in five people with HIV and is becoming more common as patients live longer.
With almost 1 million Americans, and almost 40 million people worldwide living with HIV, that's a large and underrecognized toll.
"That means HIV is the commonest cause of cognitive dysfunction in young people worldwide," says Dr. Justin McArthur, vice chairman of neurology at Baltimore's Johns Hopkins University, who treats neuroAIDS. "There's no question it's a major public health issue."
While today's most powerful anti-HIV drugs do help by suppressing levels of the virus in blood -- so that there's less to continually bathe the brain -- they can't cure neuroAIDS. Why? HIV seeps into the brain very soon after someone is infected, and few anti-HIV drugs can penetrate the brain to chase it down.
Today, anti-HIV medication has resulted in a more subtle dementia that strikes four years or more before death: At first, patients forget phone numbers and their movements slow.
Some worsen until they can't hold a job or perform other activities, but not everyone worsens -- and doctors can't predict who will. In a vicious cycle, the memory loss makes many forget their anti-HIV pills, so the virus rebounds.
If HIV patients live long enough, many specialists worry, nearly all of them may suffer at least some brain symptoms.
"They're living longer with HIV in the brain," explains Kathy Kopnisky of the National Institute of Health's National Institute of Mental Health, which is spending about $60 million investigating neuroAIDS. "And they're aging, so they're going through the normal brain aging-related processes" that can make people vulnerable to Alzheimer's and other brain diseases.
The government-funded attack has two fronts:
First, figure out which of the powerful anti-HIV cocktails are the best bet for HIV patients with memory problems.
A few of today's HIV-suppressing drugs, such as nevirapine, abacavir, AZT and indinavir, can penetrate the blood-brain barrier, says Dr. Ron Ellis of the University of California-San Diego.
But no one knows whether using those drugs instead of others will slow the brain damage once neuroAIDS symptoms begin.
Second, find drugs that protect nerve cells from the inflammation-triggered toxic chain reaction that seems to be how HIV wreaks its damage.
Topping the candidates are the epilepsy drug valproic acid and lithium, a drug long used in manic-depression. Both inhibit an enzyme called GSK-3b. The body makes the enzyme, but too much is poisonous. In the brain, HIV knocks that careful balancing act out of whack.
http://www.indystar.com/apps/pbcs.dll/article?AID=/20061015/LOCAL17/610150415/1083/LIVING01 认领了 交稿，有两句不会，大家共同看看，附上了英语。
2006，10，15
科学家挑战艾滋病痴呆
医生们无法预言哪位患者会出现“艾滋病引起的神经功能障碍”
华盛顿—艾滋病治疗的致命弱点：即使运用当今最好的药物，艾滋病毒仍然会潜入大脑，导致痴呆。
对于记忆丧失和其它可以命名为艾滋病引起的神经功能障碍的症状，科学家们已经开始试验能够阻止它们发生的药物。艾滋病患者中至少有20%的患者遭受着这种神经功能障碍的折磨，并且随着患者声生存期延长，这些症状越来越常见了。
在几乎一百万的美国人和全球四千万人为艾滋患者，这是一个巨大且无法估量的人数。
从事对艾滋病引起的神经功能障碍的治疗的 Justin McArthur博士（巴尔的摩市约翰•霍普金斯大學的神经学副主席）说，这意味着艾滋病是全球年轻人中出现认知障碍的最普遍的原因。毫无疑问这是公共卫生的主要问题。
虽然当今最有效的抗艾滋药物确实能够帮助抑制血液中的病毒水平，从而减少不断侵袭大脑的病毒，但是它们不能治疗艾滋病引起的神经功能障碍。为什么？某人感染艾滋病毒后不久病毒就会渗入大脑，然而很少有药物能穿通薛敖屏障对病毒进行追捕。
今天，抗艾滋药物已经使得患者出现更细微的痴呆现象在去世前四年或更长的时间里：首先，患者们忘记电话号码，他们的行动变得迟缓，有些出现加重甚至不能胜任工作或从事其它的活动，但不是每个人都会加重—医生们不能预言谁会出现那些情况。记忆减退使得很多患者忘记服用抗艾滋药物，形成恶性循环，病毒量反弹。
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作者:admin@医学,生命科学 2011-03-31 05:11
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