E.High-DensityLipoproteins (HDL):These newlyformed HDL are devoid ofany cholesteroland ChETheprimary apoproteinsofHDLareapoAI、CI、CII、E.Infact,amajor function of HDL is to act as circulating stores of apo CI、CIEPITheHDL are secretedby liver and intestineMuch of the lipid in HDL comes from theIrtestinalmucosasurface monolayers of chylomicrons and VLDLduring lipolysis.HDL also acquire cholesterolChIPLfromperipheral tissues in apathwaythatFAChEPLLCATprotects the cholesterol homeostasis of cellsLiverThe cholesterol isthenesterified by LCATPLleading tothe formationof largerHDL species.hULDThe cholesteryl estersaretransferredto VLDLIDL,LDL,and chylomicronremnantswiththeaid of cholesteryl ester transfer protein (CETP)MuchofthecholesterylesterthustransferredisA.:apo-A-lTG : triacylglycerolsultimately delivered to the liver by endocytosisapo-C-landapo-C-llSCh :cholesterol and cholesterol estersoftheacceptorlipoproteins.Eapo-EPL:phospholipidsLPL:lipoprotein lipaseFA :free fatty acids
16 E. High-Density Lipoproteins (HDL): These newly formed HDL are devoid of any cholesterol and ChE. The primary apoproteins of HDL are apo AI、 CI、 CII 、E. In fact, a major function of HDL is to act as circulating stores of apo CI、 CII 、E. The HDL are secreted by liver and intestine. Much of the lipid in HDL comes from the surface monolayers of chylomicrons and VLDL during lipolysis. HDL also acquire cholesterol from peripheral tissues in a pathway that protects the cholesterol homeostasis of cells. The cholesterol is then esterified by LCAT, leading to the formation of larger HDL species. The cholesteryl esters are transferred to VLDL, IDL, LDL, and chylomicron remnants with the aid of cholesteryl ester transfer protein (CETP). Much of the cholesteryl ester thus transferred is ultimately delivered to the liver by endocytosis of the acceptor lipoproteins
IL.LIPOPROTEINDISORDERSDiagnosis:Lipoprotein disorders are detected by measuring thecontent of lipids in serum after a 10-hour fastNational Cholesterol Education Program:Adult TreatmentGuidelines(1993)Total CholesterolLDL Cholesterol(mg/dL)(mg/dL)<200Desirable<130130-159Borderlinetohigh200-239>240High>160Consider as high if coronary heart disease ormore than two risk factors arepresent. A level of HDL cholesterol below 35 mg/dL is considered a major risk factorTheLDLcholesterol goal inpatients withcoronaryarterydisease is1oomg/dLorlessIdeally,triglyceridelevels should bebelow150mg/dl17
17 II. LIPOPROTEIN DISORDERS Diagnosis: Lipoprotein disorders are detected by measuring the content of lipids in serum after a 10-hour fast. Total Cholesterol LDL Cholesterol (mg/dL) (mg/dL) Desirable <200 <130 Borderline to high1 200-239 130-159 High >240 >160 National Cholesterol Education Program: Adult Treatment Guidelines (1993). Consider as high if coronary heart disease or more than two risk factors are present. A level of HDL cholesterol below 35 mg/dL is considered a major risk factor. The LDL cholesterol goal in patients with coronary artery disease is 100 mg/dL or less. Ideally, triglyceride levels should be below 150 mg/dL