Word: bloodstream
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Dates: during 1980-1989
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...polygamy, while in other regions men commonly have multiple sexual partners. Moreover, the continent is rife with other sexually transmitted maladies, such as genital ulcers and lesions caused by syphilis. Such breaks in the skin make it easier for the AIDS virus to penetrate the body and enter the bloodstream. As many as 5 million Africans are thought to harbor the virus, and at least 175,000 have developed AIDS...
...VLDL boats unload their triglycerides into body tissues, the carriers get progressively smaller, denser and proportionately more cholesterol-rich, ultimately becoming particles of LDL. The LDLs are then pulled out of the bloodstream by special protein receptors on the surface of cells. "These receptors reach out and grab cholesterol like a first baseman catching a ball thrown by a shortstop," says Dr. Michael Brown of the University of Texas Southwestern Medical Center, who, with his colleague Dr. Joseph Goldstein, won a Nobel Prize in 1985 for discovering LDL receptors. What happens to excess LDLs that are not taken...
...transport system's delicate balance can be upset by dietary indulgence. Take the case of a mythical glutton called Fred, who regularly gorges on porterhouse steak, French fries, ice cream and other foods high in saturated fats and cholesterol. Fred may feel great, but every time he eats, his bloodstream is flooded with fatty particles called chylomicrons, which transport triglycerides and cholesterol out of the intestines to the rest of | his body. Soon Fred's liver is busy mopping up chylomicrons and is unable to cope with excess LDL in the blood. The surfeit of cholesterol particles then begins circulating...
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...
Although the overall objective is to decrease the amount of total cholesterol in the bloodstream, best results are achieved by lowering levels of LDL, the "bad" cholesterol, while maintaining or increasing levels of HDL, the "good" cholesterol. The basic approach: cut down on cholesterol and saturated fats in the diet, both of which raise LDL levels, and get regular aerobic exercise, which tends to raise HDL counts. Here...