Word: hdl
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Dates: during 1980-1989
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...hopeful development is that scientists have learned how to derive synthetic HDL particles from natural HDL made in the body. At the Rogosin Institute, researchers are injecting this compound into rabbits to see if raising HDL protects them against atherosclerosis. Should such experiments succeed, it is conceivable that synthetic HDL could one day become an effective treatment for heart patients. Rogosin's Gordon notes, however, that this research "is still years away from clinical application...
...Just how HDL plays its apparently vital role in ridding the body of excess cholesterol is not entirely clear. The substance is, after all, only one element in an alphabet soup of particles that make up the so-called lipid transport system, which moves cholesterol through the bloodstream. Though individual cells can make their own cholesterol, much of their supply comes from the bloodstream, arriving from the liver aboard macromolecular ferryboats, known as very-low-density lipoproteins, or VLDLs. These carrier particles are loaded in the liver with cholesterol and dietary fats known as triglycerides, which are used by cells...
...Fred may be able to counter the effects of his gastric binges if he has enough of the HDL vigilantes in his blood. Largely produced in the liver and the intestines, these flat, disklike particles resemble "empty envelopes waiting to be filled," says Dr. Norman Miller, head of endocrinology at North Carolina's Bowman-Gray School of Medicine. As the VLDL and chylomicron particles unload their triglyceride cargoes into the body's cells, the particles become wrinkled like prunes. In the process, fragments containing proteins, fats and cholesterol break away. It is at this point that the unfilled HDL particles...
Once filled, the HDL particles must get their load of cholesterol back to the liver for excretion. Some researchers theorize that cholesterol collected in the HDL particle is transferred to a VLDL ferryboat circulating in the bloodstream; the VLDL then metamorphoses into an LDL, which is picked up by an LDL receptor in the liver. Others think HDL may in fact be a passive player -- a sort of biological signal light that indicates how efficiently excess cholesterol is being removed, without necessarily taking any direct role...
...HDL actually does have the ability to pull cholesterol out of artery walls, can high levels of HDL reverse the buildup of plaque? There are indications that this may be the case. Last year Dr. David Blankenhorn, director of atherosclerosis research at the University of Southern California, reported on a study in which 162 nonsmoking men who had undergone coronary- bypass surgery were put on a low-fat diet; 80 of them were also treated with niacin and colestipol. Among the drug-treated group, HDL levels increased 37%, while LDL decreased 43% and triglycerides went down 22%. Blankenhorn found evidence...