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Biomedical subjects

R Giunta

Publications and source records attributed to R Giunta.

At least 19 recordsLinked to original sources
PubMed1992

Decreased insulin clearance as a feature of essential hypertension.

Several studies report that essential hypertension is associated with hyperinsulinemia. This condition may depend on enhanced pancreatic insulin secretion and/or a decreased MCR of the circulating hormone. Twenty-five nonobese glucose-normotolerant patients with primary hypertension were divided into 5 groups, each consisting of 5 subjects. Each group was submitted to continuous 120-min double infusion of different doses of insulin (group I, 0.025; II, 0.05; III, 0.1; IV, 0.2; V, 0.4 U/kg.h) and glucose (I, 2; II, 3.5; III, 6; IV, 8; V, 10 mg/kg.min). The same procedures were applied to 25 healthy normotensive volunteers. Basal and steady state plasma levels of glucose, insulin, and C-peptide were significantly (P less than 0.05 or less) higher in hypertensive patients than in control subjects of all groups. The MCR of insulin (milliliters per kg/min) at all insulin-glucose infusion rates was significantly (P less than 0.05 or less) lower in hypertensive than normotensive subjects. Despite the significantly higher steady state plasma insulin levels in hypertensives, the MCR of glucose (milliliters per kg/min) was significantly (P less than 0.05 or less) lower in hypertensive than normotensive subjects. These results suggest that an altered insulin removal may contribute to the hyperinsulinemia found in the essential hypertensive subjects. In addition, a defect in insulin-stimulated glucose uptake which persists at supraphysiological insulin concentrations is confirmed in this population.

Blood Glucose↗
PubMed1992

Glutathione (GSH) improved haemostatic and haemorheological parameters in atherosclerotic subjects.

Blood samples from ten patients with clinically evident manifestations of atherosclerotic disease were used to evaluate in vitro the effects of exogenous glutathione (GSH) on platelet aggregation and on blood filtration and viscosity. In two groups, each of ten atherosclerotic patients, matched for sex, age, prevalent localization, duration and gravity of disease, the effects of GSH infusion (600 mg every day for seven days) on the haemocoagulative pattern, platelet aggregation and blood filtration and viscosity were evaluated in a double-blind, placebo cross-over trial. The GSH in vitro addition resulted in a significant increase in blood filtration and a significant decrease in blood viscosity and platelet aggregation. The venous GSH infusion both significantly decreased blood viscosity and increased blood filtration. Partial thromboplastin time was lengthened after GSH infusion even thought it remained in the normal range.

Aged↗
PubMed1989

Dietary magnesium supplements improve B-cell response to glucose and arginine in elderly non-insulin dependent diabetic subjects.

Hypomagnesemia and low erythrocyte magnesium content are both common findings in non-insulin-dependent diabetic subjects. Moreover, intracellular magnesium may play a crucial role in modulating B-cell response to glucose by interfering with potassium permeability. Eight elderly, moderately obese, non-insulin-dependent diabetic subjects were treated with either magnesium supplementation (3 g/day) to the diet or placebo. Both treatment schemes lasted 4-weeks and were separated by a 'wash-out' of 3 weeks. At the end of each treatment period, in glucose test (0.33 g/kg for 3 min) and an iv arginine (5 g) test were performed to determine the B-and A-cell responses. Dietary magnesium supplementation vs placebo produced a slight but significant decrease in basal plasma glucose (8.6 +/- 0.3 vs 8.0 +/- 0.1 mmol/l, p less than 0.05) and an increase in acute insulin response after iv glucose (3.7 +/- 2.3 vs - 14.7 +/- 0.9 pmol.l 1. (10 min)-1, p less than 0.01) and after iv arginine (151 +/- vs 81 +/- 15 pmol.l-1. (10 min)-1, p less than 0.01), respectively. Plasma glucagon levels were unaffected by chronic dietary magnesium supplementation as well under basal conditions as in response to arginine. Net increase in acute insulin response after iv glucose and after iv arginine was significantly correlated to the net increase in erythrocyte magnesium content after dietary magnesium supplementation. We conclude that magnesium administration may be a useful adjuvant to the classic hypoglycemic agents in the treatment of non-insulin-dependent diabetic subjects.

Aged↗
PubMed1988

Theophylline prevents the inhibitory effect of prostaglandin E2 on glucose-induced insulin secretion in man.

This study was undertaken to assess the mechanism by which prostaglandins of the E series inhibit glucose-induced insulin secretion in man. Acute insulin response (mean change 3-10 min) to iv glucose (0.33 g/kg) was decreased by 40% during the infusion of prostaglandin E2 (10 micrograms/min) and glucose disappearance rates were reduced (P less than 0.05). Insulin response to arginine (5 g iv) and tolbutamide (1 g iv) were not affected by the same rate of prostaglandin E2 infusion. The inhibitory effect of prostaglandin E2 on glucose-induced insulin secretion was prevented by theophylline (100 mg as a loading dose followed by a 5 mg/min infusion), a drug that increases the intracellular cAMP concentrations by inhibiting phosphodiesterase activity. Our data suggest the involvement of the adenylate cyclase system in the inhibitory action of prostaglandin E2 on glucose-induced insulin secretion in man.

Adult↗
PubMedDate not supplied

Is the common presence of glucose intolerance in old age a reliable index for the subsequent occurrence of fasting hyperglycemia?

The aim of the present study was to verify the validity of diagnostic criteria developed by the NDDG for the diagnosis of diabetes mellitus in old age. One hundred and fifty-one ambulatory old (range: 66-77 years) subjects (group A) underwent OGTT showing the following results: 33% normal, 12% non-diagnostic, 23% impaired glucose tolerance (IGT), 32% diabetic-type tolerance (DT). In addition, 84 subjects (group B) selected from 1978 to 1982 (42 aged 51-60 years, 30 aged 61-70, and 12 aged 71-80) with abnormalities of glucose tolerance during OGTT (IGT or DT) were asked to control their fasting plasma glucose every month during 1984. In group B a significant correlation between DT and subsequent development of fasting hyperglycemia was observed only in the subjects of the 6th and 7th decades of age. On the contrary, no subjects aged 71-80 years developed fasting hyperglycemia. The authors suggest that a high prevalence of abnormalities in glucose tolerance according to NDDG exists in old age which cannot be considered evidence of a true diabetes mellitus being unpredictive of a progression towards fasting hyperglycemia.

Aged↗
PubMedDate not supplied

Exaggerated orthostatic hypotension as first sign of diabetic autonomic neuropathy in the elderly.

Long-standing diabetic subjects have an impaired sympathetic nervous system activity as a consequence of autonomic neuropathy. Moreover, in this latter group of subjects the parasympathetic rather than the sympathetic nervous system seems firstly impaired by glucose metabolism derangements. In the present study we show that, in aged diabetic subjects with a short duration of the disease (less than 5 years), and who are free from diabetic complications, it is possible to evidence a primary compromise of sympathetic rather than parasympathetic nervous system activity since a greater rate of orthostatic hypotension occurred. In the light of the well-known age-related changes in the physiopathology of cardiovascular activity, we hypothesize that in aged diabetic patients, even after a short duration of disease, sympathetic compromise precedes the derangement of parasympathetic nervous system activity.

Adult↗
PubMedDate not supplied

Restoration of sensitivity to sulfonylurea after strict glycaemic control with insulin in non-obese type 2 diabetic subjects.

Ten non-obese type 2 diabetic patients with secondary failure to sulfonylureas received an intensive insulin therapy (four doses schedule) for 90 days. The glycaemic control was poor at entry (HbA1c = 11.7 +/- 1.2%) and ameliorated significantly after insulin (HbA1c = 7.1 +/- 0.7%, p less than 0.01). The reintroduction of the sulfonylurea after insulin withdrawal resulted in a persistent satisfactory long-term control (300 days) in all, but two diabetics responded no more after about 3 and 4 months of clinical remission (good control on sulfonylurea). Both basal and stimulated (iv glucagon and mixed meal) beta-cell secretory activity increased significantly at 3 months and declined thereafter without falling below baseline values. Three months of strict metabolic control seem to restore the sensitivity to sulfonylurea by enhancing beta-cell secretory activity in non-obese type 2 diabetic patients.

Blood Glucose↗
PubMedDate not supplied

Pulsatile rather than continuous glucagon infusion leads to greater metabolic derangements in insulin-dependent diabetic subjects.

The present study aimed at investigating the respective effects of continuous and pulsatile intravenous delivery of glucagon in insulin-dependent diabetic subjects. The study was performed in seven insulin-dependent diabetic subjects proven to have no residual insulin secretion. In random order and in different days each subject was submitted to glucagon delivery given continuously (58 ng/min) and in a pulsatile (377 ng/min during 2 min followed by 11 min during which no glucagon was infused) manner. In this conditions plasma glucose levels were significantly higher during pulsatile glucagon delivery. In particular in the last 65 min plasma glucose levels reached 10.8 +/- 0.3 vs 12.9 +/- 0.4 mmol/l (p less than 0.05) during continuous and pulsatile glucagon delivery respectively. Similarly plasma lipid changes also evidenced a greater effects of pulsatile rather than continuous hormone administration in producing the metabolic derangements classically encountered in insulin-dependent diabetic subjects. In conclusion, pulsatile glucagon delivery seem to produce greater metabolic effects than continuous hormone delivery.

3-Hydroxybutyric Acid↗
PubMedDate not supplied

Air pollution by gasoline exhaust fumes: effect on platelet function and blood viscosity.

Air pollution induced by automobile exhaust fumes seems to be involved in increased cardiovascular and respiratory morbidity. The effects of inhalation of such pollutant gases on platelet function and blood viscosity have not been sufficiently investigated, even if these parameters seem to be in strict correlation with cardiovascular function. Twelve healthy non-smoking volunteers were exposed for 30 minutes in a closed room to air polluted by automobile fumes. Platelet aggregation, blood viscosity, HbCO levels and P50 STD were determined before and after exposure. Cardiovascular parameters (blood pressure, heart rate and ECG) were also measured. At the end of the test, HbCO levels were significantly increased, but P50 STD was significantly reduced; an impairment of both platelet function and blood viscosity was observed. No significant changes in cardiovascular parameters were recorded. The decreases in platelet aggregation and blood viscosity were not directly correlated with either the increase in carbon monoxide levels or with the reduced P50 STD levels. It can be reasonably concluded that gasoline exhaust fumes could have been responsible for the observed alterations.

Adult↗
PubMedDate not supplied

Beta-endorphin and islet hormone release in type-2 diabetes mellitus the effects of normoglycemia, enkephalin, naloxone and somatostatin.

The present study was aimed at characterizing the effects of beta-endorphin on plasma glucose, insulin and glucagon plasma levels in subjects with type-2 diabetes mellitus. Infusion of 0.5 mg/h human beta-endorphin produced significant and simultaneous increments in both insulin and glucagon concentrations and decreased plasma glucose levels (-18 +/- 4 mg/dl, 60 min level, p less than 0.01). When the same diabetics were rendered euglycemic by an insulin infusion (1 mU/kg/min), beta-endorphin did not produce the expected decrease in plasma glucose concentrations nor raise plasma insulin levels; only the response of glucagon was preserved. Normal subjects were rendered hyperglycemic by an intravenous glucose infusion to match the plasma glucose levels of diabetic subjects. In this condition, beta-endorphin produced a significant increase of insulin concentrations, whereas glucagon remained suppressed. The intravenous administration of the long-acting met-enkephalin analogue DAMME (0.25 mg) blunted the hormonal responses to the subsequent beta-endorphin infusion in diabetic patients, although the inhibition was short-lived (30-40 min). Naloxone (5 mg), an opiate antagonist, did not produce any significant change in the insulin and glucagon responses to beta-endorphin, while somatostatin (0.25 mg/h) completely abolished the hormonal responses to the opioid.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Glucose↗