雅思閱讀真題模擬_Why did a promising heart drug fail?

中國教育在線小編為大家收集整理了雅思閱讀真題模擬：Why did a promising heart drug fail?，那么接下來就跟著小編一起來看看，相信你通過以下的文章內(nèi)容就會(huì)有更深入的了解。

Why did a promising heart drug fail?

Doomed drug highlights complications of meddling with cholesterol.

1. The failure of a high-profile cholesterol drug has thrown a spotlight on the complicated machinery that regulates cholesterol levels. But many researchers remain confident that drugs to boost levels of 'good' cholesterol are still one of the most promising means to combat spiralling heart disease.

2. Drug company Pfizer announced on 2 December that it was cancelling all clinical trials of torcetrapib, a drug designed to raise heart-protective high-density lipoproteins (HDLs). In a trial of 15000 patients, a safety board found that more people died or suffered cardiovascular problems after taking the drug plus a cholesterol-lowering statin than those in a control group who took the statin alone.

3. The news came as a kick in the teeth to many cardiologists because earlier tests in animals and people suggested it would lower rates of cardiovascular disease. There have been no red flags to my knowledge, says John Chapman, a specialist in lipoproteins and atherosclerosis at the National Institute for Health and Medical Research (INSERM) in Paris who has also studied torcetrapib. This cancellation came as a complete shock.

4. Torcetrapib is one of the most advanced of a new breed of drugs designed to raise levels of HDLs, which ferry cholesterol out of artery-clogging plaques to the liver for removal from the body. Specifically, torcetrapib blocks a protein called cholesterol ester transfer protein (CETP), which normally transfers the cholesterol from high-density lipoproteins to low density, plaque-promoting ones. Statins, in contrast, mainly work by lowering the 'bad' low-density lipoproteins.

Under pressure

5. Researchers are now trying to work out why and how the drug backfired, something that will not become clear until the clinical details are released by Pfizer. One hint lies in evidence from earlier trials that it slightly raises blood pressure in some patients. It was thought that this mild problem would be offset by the heart benefits of the drug. But it is possible that it actually proved fatal in some patients who already suffered high blood pressure. If blood pressure is the explanation, it would actually be good news for drug developers because it suggests that the problems are specific to this compound. Other prototype drugs that are being developed to block CETP work in a slightly different way and might not suffer the same downfall.

6. But it is also possible that the whole idea of blocking CETP is flawed, says Moti Kashyap, who directs atherosclerosis research at the VA Medical Center in Long Beach, California. When HDLs excrete cholesterol in the liver, they actually rely on LDLs for part of this process. So inhibiting CETP, which prevents the transfer of cholesterol from HDL to LDL, might actually cause an abnormal and irreversible accumulation of cholesterol in the body. You're blocking a physiologic mechanism to eliminate cholesterol and effectively constipating the pathway, says Kashyap.

Going up

7. Most researchers remain confident that elevating high density lipoproteins levels by one means or another is one of the best routes for helping heart disease patients. But HDLs are complex and not entirely understood. One approved drug, called niacin, is known to both raise HDL and reduce cardiovascular risk but also causes an unpleasant sensation of heat and tingling. Researchers are exploring whether they can bypass this side effect and whether niacin can lower disease risk more than statins alone. Scientists are also working on several other means to bump up high-density lipoproteins by, for example, introducing synthetic HDLs. The only thing we know is dead in the water is torcetrapib, not the whole idea of raising HDL, says Michael Miller, director of preventive cardiology at the University of Maryland Medical Center, Baltimore.

(613 words nature)

通過上文的內(nèi)容介紹，大家對(duì)“雅思閱讀真題模擬：Why did a promising heart drug fail?”大家是不是有了一個(gè)大致的了解呢？如果大家還想了解更詳細(xì)、更多的相關(guān)內(nèi)容，則可以繼續(xù)關(guān)注本頻道，也可以向本頻道咨詢。

>> 雅思 托福 免費(fèi)測(cè)試、量身規(guī)劃、讓英語學(xué)習(xí)不再困難<<