Clinica chimica acta; international journal of clinical chemistry
-
2,3-Diphosphoglycerate (2,3-DPG) modifies platelet function; it diminishes aggregation and the release reaction. The hypothesis that this occurs through a modification of the intracellular level of cyclic AMP or through an alteration in the synthesis of prostaglandins has been proposed. ⋯ It was observed that 2,3-DPG diminishes oxygen consumption induced by thrombin. This mechanism alters the platelet membrane function.
-
Comparative Study
A modified inactivation-inhibition method for determining the serum activity of alkaline phosphatase isoenzymes.
A procedure using heat inactivation and L-phenylalanine inhibition to quantitate the activities of bone, liver and intestinal alkaline phosphatase isoenzymes in human serum was confirmed by alkaline phosphatase isoenzyme analysis using an electrophoretic procedure. The results of this assay were compared with the radionuclear 85Sr test, and gamma-glutamyl transpeptidase activity in a group of patients with hepatobiliary and bone diseases.
-
The primary metabolic defect in 5-oxoprolinuria (pyroglutamic aciduria) is the lack of glutathione synthetase. The mechanism of the concomitant overproduction of 5-oxoproline was studied using cell-free extracts of erythrocytes from control individuals and from patients with 5-oxoprolinuria. Such extracts catalyzed the synthesis of 5-oxoproline from L-glutamate. ⋯ The following mechanism is postulated for the overproduction of 5-oxoproline in 5-oxoprolinuria: the deficiency of glutathione synthetase causes a lack of glutathione which is an essential feed-back inhibitor in the initial step of its biosynthesis. Therefore gamma-glutamyl-cysteine is produced in excessive amounts and it is subsequently converted to 5-oxoproline (and cysteine) by gamma-glutamyl cyclotransferase. This overproduction of 5-oxoproline exceeds the capacity of the 5-oxoprolinase and 5-oxoproline accumulates in body fluids.