Word: livers
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...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 for energy or stored for future...
...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 up by cells? Under normal conditions, these are swept by the bloodstream through the liver, where they are captured by cell receptors. The LDLs are then converted into bile acids, which are ultimately excreted...
...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 freely through the body. Unless it is stopped, it can lead to the formation of deadly plaque...
...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...