Wine: does the colour count?

The objective of this study was to determine whether phenolic constituents present in red wine and grape juice modulate plasma lipid and lipoprotein concentrations in healthy human subjects. All subjects consumed in random order 375 ml of red or white wine per day or 500 ml of two different grape juices (high and low phenols) per day for periods of 4 weeks separated by 2-week periods of abstention while continuing normal activity and food intake, and their normal lives in a community setting. The subjects were 24 healthy males aged 26-45 years screened by clinical examination and laboratory tests to exclude hypertension, diabetes mellitus, hyperlipidemia and obesity, among others. Fasting blood was collected at the beginning and end of each beverage schedule for analysis of lipids and lipoproteins. Changes in plasma lipids and lipoproteins in response to each beverage were measured to determine whether these were altered by red wine and grape juice phenolics independently of the effects of ethanol. Both grape juices had virtually no effect. Red and white wines raised plasma HDL-cholesterol and apo A-I and apo A-II concentrations as well as the apo A-I:apo B ratio to a similar extent. Red wine also raised plasma triglyceride and total cholesterol concentrations. Neither wine affected plasma apo B or apo (a) concentrations. The favourable effects of wines in modulating plasma lipid and lipoprotein concentrations are probably due to their alcohol content and cannot be reproduced by grape juices.

Methionine auxotrophy in inborn errors of cobalamin metabolism.

Several of the inborn errors of vitamin B12 (cobalamin, Cbl) metabolism (cblC, cblD, cblE, cblF, cblG) are associated with homocystinuria and hypomethioninemia due to a functional deficiency of the cytoplasmic enzyme methionine synthase which requires methylcobalamin (MeCbl) as a cofactor. We compared the growth of cultured fibroblasts from controls, from patients with a selective deficiency of MeCbl (cblE and cblG), with those with a defect in both MeCbl and adenosylcobalamin (AdoCbl) (cblC, cblD and cblF), in methionine and folic acid-free media to their growth in fully supplemented medium. Control cells were able to grow in deficient medium supplied with homocysteine, cobalamin and folate, while mutant cells were not, due to their inability to synthesize methionine from its immediate metabolic precursor, homocysteine. This differential growth is useful in screening for genetic defects of methionine biosynthesis.