Unreliability of enzymatic cholesterol analyses for the determination of electrophoretically separated lipoproteins: selective loss of HDL cholesterol.
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Chemical Precipitation↗
Biomedical subjects
J B Ubbink
Publications and source records attributed to J B Ubbink.
Further evidence on the effect of vitamin E on the cholesterol distribution in lipoproteins with special reference to HDL subfractions.
Earlier claims that oral administration of alpha-tocopherol results in significant and considerable increase in the serum total HDL concentration could not be substantiated. The present investigation does, however, show that lipoproteins are affected by alpha-tocopherol in other ways, the main effects being an increase in LDL-cholesterol and also in the HDL3-V cholesterol, an HDL3-subfraction determined by polyacrylamide gel electrophoresis. The established lipoprotein risk indices (LDL/HDL and HDL3/HDL2 ratios) were unfavorably affected as a result of alpha-tocopherol treatment. It is concluded that on the basis of available evidence, there is no reason to believe that alpha-tocopherol has a role to play in the prevention and treatment of atherosclerotic disease.
Adult↗
The direct quantification in whole serum of HDL subfractions.
A method is described for the direct electrophoretic separation in human serum of three HDL subfractions and the quantification of the cholesterol content of these by means of gas-liquid chromatography. Used in conjunction with established procedures for the separation of total HDL, VLDL and LDL on agarose gels (with gas-liquid chromatography quantification of cholesterol in each band) the procedure affords comprehensive information on lipoprotein metabolism in patients. Two technicians can process 10 samples per day, making the method suitable for semi-large scale screening of patients such as may occur in clinical trials or to evaluate in greater detail lipoprotein patterns of patients suspected of having lipoprotein abnormalities on the basis of simpler screening methods. Results obtained by the method correlate well with those obtained by means of ultracentrifugation.
Centrifugation, Density Gradient↗
Homocysteine as atherothrombotic agent: is the bark worse than the bite?
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Arteriosclerosis↗
Relationship between maternal and neonatal vitamin B6 metabolism: perspectives from enzyme studies.
Enzymes involved in vitamin B6 metabolism, i.e., pyridoxal kinase, pyridoxamine (pyridoxine) 5'-phosphate oxidase, and pyridoxal 5'-phosphate phosphatase, were assayed in hemolysates prepared from cord, maternal, and control blood samples. Mean cord and control pyridoxamine (pyridoxine) 5'-phosphate oxidase activities were significantly higher than maternal activities (p less than 0.001 and p less than 0.05, respectively). A significant correlation (p less than 0.001) was observed between maternal and cord vitamin B6-metabolizing enzymes. Cord pyridoxal 5'-phosphate levels correlated significantly with maternal pyridoxal 5'-phosphate levels (p less than 0.001) and with cord pyridoxal kinase activity (p less than 0.05). Maternal pyridoxal 5'-phosphate levels appear to be the most important factor determining fetal vitamin B6 status.
Adolescent↗