title: Direct isolation of labeled low density lipoproteins for the determination of cholesteryl ester transfer protein activity.
abstract: The measurement of the activity of cholesteryl ester transfer protein (CETP), is of high clinical interest and this study reports the use of a direct LDL isolation (d-LDL) technique to determine in one step the amount of radiolabeled cholesteryls esters ([3H]-CE) transferred from exogenous HDL3 to LDL, avoiding the conveniences of the usually used ultracentrifugation or precipitation of apo-B containing lipoproteins in the CETP methodologies. The d-LDL technique providing a specific immunoprecipitation of VLDL, IDL and HDL allowed to directly determine the [3H]-CE transferred on LDL (d-[3H]-CE-LDL). Two methodologies were assayed for the CETP activity using either exogenous or endogenous lipoproteins, and the results with the d-LDL technique were compared with those obtained using the ultracentrifugation (u-[3H]-CE-LDL) considered as the reference method. The intra- and inter-assays were similar in both techniques for the two CETP activity assays. Strong positive correlations were established between values obtained with d-[3H]-CE-LDL and u-[3H]-CE-LDL isolation procedures for CETP activities with exogenous or endogenous lipoproteins (r = 0.972; p = 0.0001 and r = 0.965; p = 0.0001 respectively). In conclusion, the d-LDL technique represents an easy and accurate procedure to measure directly, in normotriglyceridemic plasmas, the amount of [3H]-CE transferred from HDL to LDL by the CETP.
authors.affiliation: Laboratoire de Biochemie des Lipides, Hôpital de la Pitìé, Paris, France.
authors.forename: D
authors.initials: D
authors.lastname: Sich
authors.forename: Y
authors.initials: Y
authors.lastname: Saïdi
authors.forename: M
authors.initials: M
authors.lastname: Egloff
authors.forename: P
authors.initials: P
authors.lastname: Giral
authors.forename: V
authors.initials: V
authors.lastname: Gautier
authors.forename: M C
authors.initials: MC
authors.lastname: Federspiel
authors.forename: G
authors.initials: G
authors.lastname: Turpin
authors.forename: I
authors.initials: I
authors.lastname: Beucler
mesh_terms: D002352:Carrier Proteins / Q000097:blood*; D053480:Cholesterol Ester Transfer Proteins; D002788:Cholesterol Esters / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D006023:Glycoproteins; D006801:Humans; D006937:Hypercholesterolemia / Q000097:blood; D008077:Lipoproteins, LDL / Q000097:blood* / Q000302:isolation & purification*; D012016:Reference Values; D014316:Tritium; D014461:Ultracentrifugation
chemical_list: C506642:CETP protein, human; D002352:Carrier Proteins; D053480:Cholesterol Ester Transfer Proteins; D002788:Cholesterol Esters; D008078:Cholesterol, LDL; D006023:Glycoproteins; D008077:Lipoproteins, LDL; D014316:Tritium