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Biomedical subjects

M Varricchio

Publications and source records attributed to M Varricchio.

At least 181 records · Page 10Linked to original sources
PubMedDate not supplied

Modulation by verapamil of insulin and glucagon secretion in man.

The present investigation was designed to evaluate the effect of acute and protracted verapamil administration on insulin and glucagon secretion in man. For this purpose, 14 normal subjects received two consecutive glucose pulses (5 g.i.v. in less than 20 sec or 20 g.i.v. in less than 1 min, 7 subjects for each group), 70 or 90 min apart, before and during an infusion of verapamil (160 microgram/min). Seven additional normal subjects received two consecutive arginine pulses (5 g i.v.), 70 min apart. In 14 inpatients with coronary heart disease, we investigated the effect of protracted verapamil administration. Seven of these subjects underwent two oral glucose tolerance tests (100 g) and the other 7 two arginine tests (30 g) before and after a 10-day treatment with verapamil, 240 mg/die p.o. divided into three doses; the last dose, 80 mg, was given orally 1 h before the performance of the post-treatment test. Verapamil significantly inhibited the acute insulin response (AIR, mean change from 3-10 min) to glucose (5 g), as well as the AIR and AGR (acute glucagon response) to arginine (5 g). By contrast, verapamil failed to alter significantly the AIR to the higher glucose pulse. There was no significant change of oral glucose tolerance after verapamil, nor was there a change in insulin response to oral glucose. By contrast, insulin and glucagon responses to arginine infusion were significantly reduced by the drug.

Adult↗
PubMedDate not supplied

Hemodynamic effects of somatostatin in insulin-dependent diabetic subjects.

The aim of the present study was to evaluate possible hemodynamic effects of somatostatin in insulin-dependent diabetic subjects. For this purpose, 7 insulin-requiring juvenile-onset diabetics were submitted to a short-term infusion of cyclic somatostatin (250 micrograms/h, over 2 h) or saline in randomized order. Somatostatin infusion resulted in a progressive and significant decrease in heart rate, stroke volume, cardiac index and velocity circumferential fiber; on the other hand, left ventricular ejection time was augmented by somatostatin. None of these effects was seen in the saline control study. We conclude that somatostatin exerts a negative inotropic effect in insulin-dependent diabetes.

Adult↗
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

Glucose intolerance in the elderly: an open debate.

The presence of glucose intolerance in aged people is a well known physio-pathological condition. Nevertheless, the mechanisms by which it takes place are still unclear. In the present report we have reviewed the possible mechanisms (impaired insulin secretion and action, role of the environmental factors) which may contribute to the impaired glucose handling of aging. Moreover, we have also pointed out that not all aged subjects are glucose intolerant; in fact it seems clear that only aged subjects who present more than one of the pathological findings reported above may develop impaired glucose handling.

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Changes in glucose turnover parameters during muscular exercise: role of age.

In a study of ten young and seven elderly healthy men we have performed an oral glucose tolerance test (75 g) and employed a euglycemic hyperinsulinemic (0.25 mUx kg/min) glucose clamp technique in order to determine insulin sensitivity. This latter experimental protocol consisted of 120 min of euglycemic clamp followed by 60 min in which the clamp and a mild muscular exercise (35% VO(2) (max)) were combined. D-[(3)H]glucose infusion allowed a determination of the glucose turnover parameters. Our results show that in elderly subjects glucose disappearance rate and glucose metabolic clearance rate are significantly lower during both clamp, and clamp + muscular exercise studies. On the contrary, hepatic glucose production was similar under both conditions and was independent of age.

Journal Article↗
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Insulin resistance as cause of increased blood pressure in the elderly: effects on intracellular ion contents.

Previous reports have evidenced a strong relationship between high plasma insulin levels and blood pressure in diabetic and obese subjects but not in the elderly. During aging many patho-physiological changes in cardiovascular functions and autonomic nervous system occur, so that aging per se might be a cause of a 'physiological' increase in blood pressure. Nevertheless, an insulin resistance also develops during aging. The present study investigates the possible role of age-dependent insulin resistance in the genesis of increased blood pressure. Our data show that insulin resistance calculated by the glucose infusion rate during a euglycemic hyperinsulinemic glucose clamp procedure is significantly correlated with the insulin-mediated net decrease in erythrocyte Na+ content (r = 0.58, P < 0.05), as well as with net increase in erythrocyte K+ (r = 0.64, P < 0.05) and Mg2+ (r = 0.67, P < 0.01) content and to basal diastolic blood pressure (r = -0.63, P < 0.05). We conclude that in elderly subjects the age-related and normally occurring insulin resistance might contribute to the increase of arterial blood pressure through its effect on cell cation content.

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The combined insulin and sulfonylurea therapy in diabetes of elderly people.

The usefulness and safety of the combined insulin-sulfonylurea (gliclazide) therapy were investigated in 70 elderly diabetic patients poorly controlled by insulin alone. More than half (45 diabetics, 64% of total) ameliorated significantly their metabolic control after six months of the combined treatment: not only the glycemic profile and glycated hemoglobin Alc were significantly decreased, but the daily insulin dose was reduced by approx. 35% (p < 0.01). These positive results in terms of improved glycemic control as well as reduction of daily insulin needs were still present after a mean period of follow-up of 5 years. The good percentage of positive results, the small incidence of hypoglycemic episodes and the consistent reduction of peripheral hyperinsulinism make this intervention (insulin-gliclazide) a safe strategy that can be adopted in a population of elderly diabetics, poorly controlled on insulin alone.

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Metabolic effects of nitrendipine.

A randomized, double-blind, placebo-controlled study was conducted to evaluate the safety and clinical efficacy of nitrendipine in the treatment of isolated systolic hypertension in elderly patients. The subjects were 20 elderly patients with isolated systolic hypertension who received 20 mg of nitrendipine or placebo daily for 60 days. In the nitrendipine-treated patients, both systolic and diastolic blood pressures were reduced significantly during treatment (from a mean of 180 to 155 mmHg and 92 to 80 mmHg); heart rate did not change significantly. Standard laboratory test results did not change in either group during treatment and results of a posttreatment oral glucose tolerance test were similar in the two treatment groups.

Aged↗
PubMedDate not supplied

Impaired insulin-mediated erythrocyte magnesium accumulation is correlated to impaired insulin-mediated glucose diposal in aged non-diabetic obese patients.

Basal erythrocyte magnesium levels were significantly lower in obese than lean subjects. In vitro incubation in the presence of 100 mU/l insulin significantly increased magnesium erythrocyte levels in both groups of subjects. However, even in the presence of 100 mU/l, the erythrocyte magnesium content of obese patients was lower than that of control subjects. The in vitro dose-response curve of the effect of insulin on magnesium erythrocyte accumulation was shifted to the right when the red cells of obese were used, with a highly significant reduction of the maximal effect. Such reduction of the maximal effect of insulin suggests that the impairment of insulin-induced erythrocyte magnesium accumulation observed in obese patients results essentially from a post-receptor defect. In obese patients, net increase in erythrocyte magnesium levels (calculated as the difference between basal and 100 mU/l insulin-induced erythrocyte magnesium levels) was negatively correlated with basal plasma insulin levels (r = 0.79 p less than 0.01), and with body mass index (r = 0.81 p less than 0.01) while it was positively correlated with the glucose disappearance rate after glucose load (r = 0.67 p less than 0.05) and glucose metabolic clearance rate (r = 0.71 p less than 0.01). These results demonstrate that insulin-induced erythrocyte magnesium accumulation is impaired in patients with obesity and that such defect is correlated to impaired -- mediated glucosal disposal in the patients.

Aged↗
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

[Behavior of hemodynamic and blood-gas parameters after intravenous salbutamol].

The haemodynamic effects of salbutamol were studied in 14 patients with chronic obstructive lung disease with a single dose of 100 and 200 gamma, administered by i.v. injection. The results of study revealed salbutamol intravenous injection significantly increases heart rate, cardiac index and decreases vascular systemic resistance. There was no significant change in blood gas tensions. This study indicates that salbutamol produces variation in preload and afterload by a direct action on vascular smooth muscle.

Albuterol↗