No abstract

To investigate the pathophysiology of diabetic osteopenia, circulating levels and bone contents of bone gamma-carboxyglutamic acid-containing protein (BGP) were measured in streptozocin-induced diabetic rats . Plasma calcium and total protein were significantly decreased (P less than .01) in the diabetic group, and the plasma level of BGP in diabetic rats was 19.6 +/- 2.8 (mean +/- SE) ng/ml, which is significantly lower than the value of 89.2 +/- 14.0 ng/ml in control rats (P less than .01). Bone contents of calcium and hydroxyproline per femur were significantly decreased in the diabetic group (P less than .01), and the ratios of bone calcium to hydroxyproline were not different. Bone BGP content per femur in the diabetic group was 669 +/- 58 micrograms, which was also significantly lower compared with 1241 +/- 126 micrograms in control rats (P less than .01). The decreased bone content of BGP is consistent with the hypothesis that BGP synthesis is impaired in insulin-deficient diabetes. Because a relationship between plasma levels of BGP and bone turnover has been established, the low plasma BGP value suggests there is a decrease in bone turnover in diabetic rats. Therefore, we postulate that the low bone turnover is one of the pathological features of diabetic osteopenia and is at least partly responsible for the occurrence of this complication in diabetes mellitus.

No abstract

No abstract

No abstract

We measured bone gamma-carboxyglutamic acid-containing protein (BGP), calcium (Ca), phosphorus (P), and alkaline phosphatase (Al-P) in paired maternal and cord sera, and urinary gamma-carboxyglutamic acid (gamma-Gla) in neonates. The circulating BGP was 41.21 +/- 2.47 ng/ml and 7.44 +/- 0.87 ng/ml in the cord (n = 15) and the maternal (n = 14) sera, respectively. The urinary gamma-Gla in the neonates was 147.68 +/- 10.75 mumol/g creatinine (n = 15). The cord serum BGP was significantly higher than the normal adult level. The maternal serum BGP was at the same level as in other adults. It is conceivable that the fetus may produce BGP during gestation, as the cord serum BGP level was significantly higher than the maternal level and there was no correlation between the cord and maternal serum BGP concentrations. The reason for the elevated circulating BGP level in the cord serum is not known, but increased bone turnover may be a factor. The cord serum BGP may include not only carboxylated but also non-gamma-carboxylated GP because of fetal vitamin K deficiency.

SummaryCharacteristics of early appearing free isomaltase in the soluble fraction were investigated in rat intestinal mucosa . Soluble isomaltase and membrane-bound sucrase-isomaltase complex were pre pared from 15-day-old rat intestine. Immunochemical properties, optimal pH and heat sensitivity of soluble isomaltase were compared with those of membrane-bound isomaltase. Optimal pH of free isomaltase in the soluble fraction was lower than that of membrane-bound isomaltase. Soluble and membrane-bound isomalt ase showed different sensitivities for temperature . Furthermore, membrane-bound isomaltase in 15-day-old suckling rat intestine gave a single line with antiserum. However, soluble isomaltase gave no precipitin line. From these results, it could be concluded that soluble isomaltase is not derived from the isomaltase moiety of membrane-bound sucrase isomaltase complex as a result of mechanical fragility and rather it would be lysosomal in origin.

No abstract