No abstract

No abstract

Although menaquinones are biologically active forms of vitamin K, factors that influence their production by bacteria or their absorption from the gut are not well understood. Germ-free rats were inoculated with four different strains of organisms and fecal and tissue menaquinone concentrations were determined. No menaquinones were detected in the tissues or feces of rats colonized with Bifidobacterium longum or Clostridium ramosum, two organisms that have not been reported to produce menaquinones when grown in pure cultures. Rats colonized with Bacteroides vulgatus had high levels of fecal MK-10 with significant amounts of MK-9 and MK-11, whereas rats colonized with Escherichia coli had high levels of fecal MK-8 and small amounts of MK-7. The same menaquinones are produced in pure cultures of these organisms. The predominant fecal menaquinones were also detected in liver and were present in higher concentrations in the liver of those rats not maintained in coprophagy-preventing cages.

No abstract

We developed a novel method for measuring glycated (glc) proteins in biological samples, based on the colorimetry of 2-keto-glucose which is released from the glc protein (ketoamine) on heating with hydrazine. The ketoamine-induced coloration remained constant at room temperature (25-27 degrees C) for 1 h. The method gave reliable precision and accuracy. However, high concentrations of serum pigments caused positive interference, suggesting that hemolytic or hyperbilirubinemic serum would give false-positive results. The concentration of glc protein in clinical serum samples measured by the present method (y) correlated well with those (fructosamine values, x) measured by the nitroblue tetrazolium-reducing method: y = 1.27x-1.69 (r = 0.92, n = 93). The concentrations (microM, mean +/- S.D.) of glc protein in sera from normal and diabetic subjects were 275 +/- 37 (n = 32) and 403 +/- 98 (n = 32), respectively, and the concentrations (nmol/mg hair, mean +/- S.D.) of glc protein in back hairs from non-diabetic and diabetic rats were 3.7 +/- 0.3 (n = 10) and 8.6 +/- 1.5 (n = 10), respectively. Thus, the technique gave reasonable concentrations of glc proteins in humans and rats with diabetes mellitus, indicating it to be reliable and diagnostically useful.