If this is not your name, click here.
| | If this is not your name, click here. | | |
| | Contact Us | Order Now | Journals | Bookstore | Register a colleague | | |
| |  Obscure Enzyme May Play Major Role In Heart Disease NEW YORK, NY and HAIFA, ISRAEL -- April 15, 1998 -- A little-known enzyme may play a significant role in preventing heart attack. A paper appearing today’s Journal of Clinical Investigation reports that paraoxonase, an enzyme present in the blood, prevents the oxidation of low-density lipoprotein or LDL, the bad cholesterol that is deposited in blood vessels and leads to coronary heart disease. The paper is written by Michael Aviram, a biochemist, head of the Lipid Research Laboratory, faculty of medicine at the Technion-Israel Institute of Technology and at Rambam Medical Center in Haifa, Israel. "Paraoxonase is located in the blood on the HDL, the good cholesterol, and it can break down oxidised LDL to non-harmful products," explained Aviram, adding that the discovery of this enzyme's activity opens a possible new route to prevention of heart diseases. The real function of the enzyme has been something of a mystery since it was discovered more than 40 years ago. Its previously known function was to break down organophosphates, chemicals that are used as insecticides and poison gases. That activity was obviously not the complete story of paraoxonase, as humans do not normally contain these substances in their blood, Aviram explained. Since the major focus of his past research has been the study of the mechanisms by which oxidised cholesterol and other oxidised lipids accumulate in arterial wall cells, leading to blockage of arteries and formation of atherosclerotic lesions, he decided to study the effect of the enzyme on oxidised lipids. Researchers had previously found a very strong inverse relationship between the activity of paraoxonase in the blood and the risk of heart disease. Lower activity is associated with higher risk. The present study helps us understand the mechanism behind that relationship. In experiments with a strain of mice that are vulnerable to atherosclerosis, an inverse relationship between cholesterol oxidation and paraoxonase activity was shown. In addition, an increase in the size of the atherosclerotic lesions in the blood vessels of these mice was found to be related to the reduction in paraoxonase activity. The next step is to find out how to regulate the activity of paraoxonase and to increase its level in human blood, the Aviram write. "If we can find means of changing the enzyme activity, we can look for methods of intervention," he said. "This could have very strong implications for heart disease therapy."
|
