Biomedical subjects
Publications and source records attributed to G Pozza.
60 min after the injection of therapeutic doses of vincristine for cancer chemotherapy, there is a reduction of the total (40%) and of the acute phase (43%) areas of insulin secretion inductedby 5-g i.v glucose load, and the constant of gllcose utilization is reduced by 25%. No differences are observed after 3 5-g i.v. glucose loads given at hourly intervals in control subjects.
Juvenile-onset diabetics (JOD) have a significantly low peripheral T-lymphocyte count. In vitro exposure of diabetic lymphocyte cultures to insulin causes a significant T-cells count increase and thereafter no significant difference is detectable among JOD, maturity-onset diabetics (MOD) and normal subjects (NS) T-cells counts. This finding supports the hypothesis that the T-lymphocyte depressed function present in JOD is a secondary phenomenon due to in vivo insulin deficiency. Possible mechanisms of insulin action in restoring E-rosette function are discussed.
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In seven normal subjects the repeated oral administration of metergoline, a specific antiserotonin agent, has enhanced HGH response to arginine infusion. Following placebo administration, arginine-induced HGH release was slightly but not significantly reduced; similarly, in eight metergoline treated subjects, HGH response to oral L-Dopa was slightly but not significantly reduced. HGH response to i.v. L-Dopa was not modified by the drug. These results suggest that serotonin controls HGH response only in response to arginine, not to L-Dopa.
Histamine is found in most tissues including the central nervous system. Here it reaches the highest concentrations in the hypothalamus and in the median eminence. In order to evaluate the possible role of endogenous histamine in the control of human growth hormone (hGH) secretion, we investigated the effect of two anti-histamine drugs, meclastine and dexchlorpheniramine, on the hGH response to arginine infusion and to insulin hypoglycemia in 30 normal subjects. The oral administration of meclastine for three days or the intravenous infusion of dexchlorpheniramine significantly reduced the hGH response to arginine infusion. Neither drug affected the secretion of hGH following insulin hypoglycemia. These results suggest that histamine is involved in the control of hGH release, at least in response to arginine. Our data are consistent with the finding that histamine stimulates GH release in the baboon (Meyer and Knobil, Endocrinology 80: 163, 1967) and with previous results indicating that the release of hGH in response to different stimuli is subject to different regulatory mechanisms.
The percentage and absolute number per mm.3 of peripheral T-lymphocytes were determined in 11 juvenile-onset diabetics (JOD), in 21 maturity-onset diabetics (MOD), and in 18 normal subjects (NS). The percentage was significantly lower in JOD (38.1) than in MOD (57.2) and NS (56.5). The absolute T-lymphocytes number per mm.3 was significantly lower in JOD (833) than in NS (1,260); this was also true for JOD as against MOD (1,026), even if the difference was not statistically significant. No difference was found between MOD and NS, or between MOD on oral therapy and on insulin treatment. The decrease of peripheral T-lymphocytes in JOD was not related to associated illness or drugs. The data presented suggest the possibility of an altered cell-mediated immunity in juvenile-onset diabetics.
The effect of metergoline on insulin secretion has been evaluated in normal subjects and in patients with chemical diabetes. The repeated administration of metergoline, 2 mg at four-hour intervals to give a total of 24 mg, has enhanced insulin secretion in response to i.v. glucose in normal subjects but not in chemical diabetics. No changes in blood glucose pattern were observed. Under similar conditions, metergoline administration caused a slight but significant decrease in arginine-induced insulin release, both in normal subjects and in chemical diabetics. These results support the concept of a serotoninergic control of insulin secretion and suggest that serotonin exerts different effects on insulin release according to the different stimuli.
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