الدهون

? Cholesterol is an essential lipid constituent of cell membranes
? Cholesterol is a precursor of steroid hormones and of bile acids
? Intermediates of cholesterol biosynthesis are required to make vitamin D and for posttranslational modification of membrane proteins
? High plasma cholesterol promotes atherosclerosis
? intestinal uptake of dietary cholesterol
? de novo cholesterol synthesis
? synthesis of steroid hormones from cholesterol
? synthesis of bile acids from cholesterol, and their biliary secretion
? biliary secretion of surplus cholesterol in unmodified form
? cholesterol uptake, synthesis and degradation
? cholesterol transport in the circulation: LDL (low density lipoprotein) and HDL (high density lipoprotein)
? biochemical changes that turn physiological, benign LDL into an atherogenic agent
? inhibition of cholesterol synthesis
? inhibition of cholesterol uptake
? inhibition of cholesterol ester transfer protein
? inhibition of bile acid reuptake
? LDL apheresis
? Blood is diverted through an extra-corporeal filtration device
? cells are separated from plasma
? LDL is removed from plasma by affinity methods or size-based filtration
? The remaining plasma and cells are returned to the circulation
? The procedure is repeated in weekly or biweekly intervals
? triparanol—an old drug, inhibits some CYP450 enzymes in the conversion from lanosterol to cholesterol; withdrawn due to toxicity
? bezafibrate—a PPAR? agonist
? nicotinic acid—activates hormone-sensitive lipase through a G protein coupled receptor named HM74A; 5 likely additional mechanisms
? probucol and succinobucol—supposedly antioxidants that prevent LDL oxidation, but also cause unrelated changes in other laboratory parameters
? guar gum and other carbohydrate fibers —absorb and prevent intestinal uptake of cholesterol and bile acids with variable efficiency
? thyroid hormone analogs—promote LDL utilization