Biomedical subjects

R Staffolani

Publications and source records attributed to R Staffolani.

38 records · Page 3Linked to original sources

PubMedDate not supplied

Effects of diabetes mellitus on structural and functional properties of erythrocyte membranes.

Diabetic patients present alterations in the activity of a number of enzymes of the plasma membrane. The aim of this study was to verify if the modifications of the enzymatic activities in diabetes mellitus are associated with structural alterations of the cellular membrane. By means of the freeze-fracturing technique, we studied the structure of erythrocyte membranes from 15 insulin-dependent diabetic patients (24-43 years) and 15 age-matched healthy subjects (26-47 years). The kinetic properties of the Na+/K(+)-ATPase of the same membranes were also investigated. The Na+/K(+)-ATPase of the erythrocyte plasma membrane shows an uncompetitive inhibition in the diabetic subjects. As for the freeze-fracturing results, the intramembrane particles of the erythrocyte membranes from diabetic patients appear more clustered with respect to those obtained from controls. The uncompetitive inhibition of the enzyme suggests the presence of conformational modifications of the protein. This hypothesis is supported by the freeze-fracture results which indicate that the integral protein constituents of the membrane in diabetes tend to aggregate. Modifications of the interactions between the enzymatic subunits and the membrane lipid environment might be at the basis of the Na+/K(+)-ATPase alteration in diabetes.

Adult↗

PubMedDate not supplied

Functional platelet modifications induced by oral magnesium supplementation in normotensive and hypertensive pregnancy.

Platelet functionality alterations have been correlated to the onset of hypertension in pregnancy and oral Mg++ supplementation has been clinically postulated to counteract such alterations. We, therefore tested the effect of 4 weeks oral Mg++ pyrrolidone carboxylate supplementation on platelet function. Forty-eight pregnant women were enrolled in the study at the beginning of the third trimester (30-32 weeks). Twenty women were preeclamptic, while 28 remained normotensive and served as controls. All the women received 360 mg/day magnesium pyrrolidone carboxylate for 4 weeks. DPH fluorescence, Na+/K(+)-ATPase and Ca(++)-ATPase activity, intracellular free Ca++ concentrations were determined prior and after the 4-weeks supplementation. Oral Mg++ supplementation significantly increased platelet DPH fluorescence in both normotensive and preeclamptic women. In normotensive pregnant women, it also significantly increased the activity of Na+/K(+)-ATPase, the activity of Ca(++)-ATPase and reduced the concentration of intraplatelet free Ca++. In hypertensive pregnant women, Mg supplementation increases Na+/K(+)-ATPase activity and decreases intracellular free Ca++; this, in turn, contributes to reducing the activity of Ca(++)-ATPase. Magnesium supplementation to preventing hypertension in pregnancy seems to have a consistent biochemical and clinical background.

Administration, Oral↗