alpha-cyclodextrin and Hyperlipidemias

We have developed a fully automated method for measuring LDL-cholesterol (LDL-C) in human serum without the need for prior separation, using a nonionic surfactant, polyoxyethylene-polyoxypropylene block copolyether (POE-POP), and a sodium salt of sulfated cyclic maltohexaose, alpha-cyclodextrin sulfate. Of the surfactants tested, POE-POP with a higher molecular mass of the POP block and a greater hydrophobicity reduced the reactivity of cholesterol in lipoprotein fractions; the reactivity in descending order was LDL >> VLDL > chylomicron approximately HDL. Gel filtration chromatographic studies revealed that POE-POP removed lipids selectively from the LDL fraction and allowed them to participate in the cholesterol esterase-cholesterol oxidase coupling reaction system. By contrast, alpha-cyclodextrin sulfate reduced the reactivity of cholesterol, especially in chylomicrons and VLDL. A combination of POE-POP with alpha-cyclodextrin sulfate provided the required selectivity for the determination of LDL-C in serum in the presence of magnesium ions and a small amount of dextran sulfate without precipitating lipoprotein aggregates. There was a good correlation between the results of LDL-C assayed by the proposed method and the beta-quantification reference method involving 161 sera with triglyceride concentrations ranging from 0.3 to 22.6 mmol/L.

Topics: alpha-Cyclodextrins; Automation; Cholesterol; Cholesterol Oxidase; Cholesterol, LDL; Chromatography, Gel; Cyclodextrins; Humans; Hyperlipidemias; Indicators and Reagents; Lipoproteins, HDL; Lipoproteins, LDL; Lipoproteins, VLDL; Phospholipids; Poloxalene; Pseudomonas; Reference Values; Reproducibility of Results; Sensitivity and Specificity; Sterol Esterase; Surface-Active Agents; Triglycerides

The optical aberrations due to the presence of the turbidity caused by hyperlipidemia has been eliminated in two serum glucose procedures. This has been accomplished by incorporating lipase and alpha-cyclodextrin into the two glucose reagents. The hydrolytic action of the lipase generates water soluble glycerol and insoluble fatty acids. By including the chemical scavenger alpha-cyclodextrin into the reagent the fatty acids are solubilized and thus the production of a second turbidity is avoided. Because the clearing reagents are incorporated into the glucose reagents, this is an on-line process and no additional labor is required to clear the sample-reagent mixture. Furthermore, no additional time is required as the clearing occurs in the same period of time that it takes for the indicator reactions to reach equilibrium.

Topics: alpha-Cyclodextrins; Blood Glucose; Cyclodextrins; Fatty Acids, Nonesterified; Glucose Oxidase; Hexokinase; Humans; Hyperlipidemias; Indicators and Reagents; Lipase; Spectrophotometry; Triglycerides