Search PubMed⌕ Search

Biomedical subjects

R De Pirro

Publications and source records attributed to R De Pirro.

48 records · Page 3Linked to original sources
PubMed1980

Arginine does not influence insulin binding on circulating monocytes.

Glucose ingestion, food intake or acute exercise produced rapid variations in insulin binding on monocytes. Insulin seems to play a minor or any role in this phenomenon in contrast pancreatic glucagon might be involved since it usually rises when an increase in insulin receptor affinity has been observed. To investigate the role of pancreatic glucagon we have studied the effect of arginine infusion on monocyte insulin receptor in five normal subjects. Results indicate that the aminoacid employed does not induce any change in insulin receptor affinity and concentration suggesting that the simultaneous increase in plasma insulin and pancreatic glucagon levels does not exert any action.

Adult↗
PubMed1979

Aggregation-induced stability of dexamethasone receptors in rat kidney.

The stability of the dexamethasone-receptor complex of rat kidney cytosol was studied using homogenizing media of varying pH and composition. It was found that the complex is less stable with buffers usually employed for the study of steroid receptors such as Tris, EDTA etc., whereas the stability increases considerably with a solution composed of monothioglycerol 12 mmol/l and glycerol 5% in distilled water. Sepharose 4-B column chromatography revealed that the increased stability was associated with a larger form (probably an aggregate) of the receptor-steroid complex.

Animals↗
PubMed1979

The effect of food intake on insulin receptor in man.

Insulin binding to circulating monocytes was studied in 22 normal volunteers before and 1, 3 and 5 h after a 1400 Kcal meal. Results indicate that 3 h after food intake there is an increase in the specific cell binding fraction (P less than 0.001) with a change in receptor affinity. Data emerging from the present study demonstrate that there are rapid changes in insulin receptor properties during the day. These changes probably play a role in the regulation of the hormonal and metabolic pattern in normal subjects.

Adult↗
PubMed1979

Specificities of rabbit anti-human insulin receptor antibodies.

Human insulin receptors obtained from normal human placentae were highly purified by affinity chromatography and used to immunize rabbits. The immunological response was evaluated in order to reveal the presence of antibodies blocking the binding of insulin to monocytes of normal subjects. Since no blocking activity was found IgG from rabbits were coupled to agarose in order to evaluate the presence of antibodies directed to determinant(s) other than the insulin binding site. One rabbit was found to produce antibodies binding the insulin receptor on a site different from the insulin binding site.

Animals↗
PubMed1978

Insulin receptors during the menstrual cycle in normal women.

Specific binding of 125I-insulin to circulating monocytes from eight normal menstruating women, four postmenopausal women and four men were studied four times during a 28-day period (one sample at 7-day intervals). Data indicate the presence of a higher specific cell binding fraction in the follicular phase compared to the luteal phase due to changes in insulin receptor concentration. No changes were observed in men or postmenopausal women during the same period of time suggesting that sex hormones should be included among the factors influencing insulin receptors.

Adult↗
PubMedDate not supplied

Response of insulin receptors to oral glucose in normal subjects.

Insulin binding to circulating monocytes was studied in ten male volunteers before and 1, 2, and 5 hours after the oral intake of 100 g of glucose. Results indicate an increase in the specific cell binding fraction with a change in receptor affinity 5 hours after glucose. Since the same changes appear 3 hours after food intake they are probably not directly induced by insulinemia.

Adult↗
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

[Attempts to characterize dexamethasone receptors present in rat kidney cytosol].

Density gradient centrifugation analysis has been used to study rat kidney receptors for dexamethasone. Density gradients performed with cytosol incubated with 3H-dexamethasone in a Tris 10 mM, EDTA 1.5 mM, glycerol 5%, monothioglycerol 12 mM (pH 7.5) buffer never gave any good evidence of a 85 radioactivity peak probably due to instability of the complex. The stability of the complex for at least 30 h was achieved by homogenizing the tissue and incubating cytosol in a distilled water, glycerol 5% monothioglycerol 12 mM solution. Density gradient centrifugation analysis in this way showed radioactivity peak at the bottom of the tube probably due to the aggregation of the complex. Since this drawback is inherent in the technique it must be concluded that density gradient centrifugation analysis cannot be used to study the dexamethasone-receptor complex of the kidney.

Animals↗