Cholesterol oxidase-based determination, by continuous-flow analysis, of total and free cholesterol in serum.

Abstract

We describe a continuous-flow, automated determination of total cholesterol in serum, which is based on enzymatic hydrolysis of cholesterol esters, oxidation of cholesterol by cholesterol oxidase, and colorimetric measurement of liberated perioxide with 4-aminoantipyrine, phenol, and peroxidase. Free cholesterol is determined with the same AutoAnalyzer II manifold and reagents, except that cholesterol esterase is omitted from the reagent. Cholesterol-in-serum materials that have been assayed by an established method are used for calibration. We found this approach to be necessary because primary cholesterol standards in organic solvents are incompatible with the aqueous reagent. Results of the enzymatic total cholesterol method correlated well with those by an AutoAnalyzer II method which involves an extraction with isopropanol and the Liebermann-Burchard color reaction (total cholesterol, g/liter, yenz= 0991xlb +0.05;r=0.996). Results of the enzymatic free cholesterol procedure agreed satisfactorily with one in which free cholesterol is precipitated as the digitonide and subsequently analyzed colorimetrically with the Liebermann-Burchard reaction (free cholesterol, %, yenz = 0.982xdig -0.7;r= 0.956).

Measurement of free fatty acid kinetics during non‐equilibrium tracer conditions in man: implications for the estimation of the rate of appearance of free fatty acids

“…Lipids were measured in unfrozen serum and in the high-density lipoprotein (HDL) containing supernatant fraction after precipitation of apolipoprotein B-containing lipoproteins with sodium phosphotungstate and magnesium chloride [19]. Cholesterol and triglyceride were measured enzymatically using automated methods [20,21]. Haemoglobin A 1c (HbA 1c ) was measured by high-performance liquid chromatography (Bio-Rad, Veenendaal, The Netherlands; normal range 4·6-6·1%).…”

“…Ten minutes after stopping the infusion, the SA 20 will still be higher than SA 0 , making (SA 20 -SA 10 ) ¼ x 2 × (SA x -SA 0 ), and the AUC during the decline from SA 10 to SA 20…”

Composition du liquide seminal de Sparus aurata au cours d'une saison de spermiation

“…Elles portent sur les protkines totales, le glucose, les triglyctrides, le cholesterol et le calcium. Les methodes de dosage utilisees reposent respectivement sur les travaux de Skeggs et Hochstrasser (1964), Trinder (1969), Fossati et Prencipe (1982), Lie et al (1976) et Gitelman (1967, adaptes aux analyseurs Technicon R.A.…”

Do the MN and Jk systems influence environmental variability in serum lipid levels?

“…Plasma total cholesterol and triglycerides were measured on a Technicon SMAC by enzymatic methods (Lie et al 1976, Bucolo & David 1973. HDL cholesterol was measured on plasma samples to which EDTA had been added, by enzymatic assay after polyethylene glycol precipitation .…”