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Biomedical subjects

M Muggeo

Publications and source records attributed to M Muggeo.

At least 145 records · Page 8Linked to original sources
PubMed1978

Insulin resistance, acanthosis nigricans, and normal insulin receptors in a young woman: evidence for a postreceptor defect.

We have previously described a group of young females with virilization, acanthosis nigricans, insulin resistance, and markedly decreased binding of insulin to its receptor (syndrome of insulin resistance and acanthosis nigricans type A). The present report concerns a 15-yr-old female with clinical features indistinguishable from the type A patients, including virilization, acanthosis nigricans, and extreme resistance to endogenous and exogenous insulin. Insulin levels were 400-650 microU/ml while fasting and were over 2200 microU/ml when stimulated. Proinsulin was less than 10% of the total immunoassayable insulin. In distinct contrast to the type A patients, insulin receptors on cells from this patient were entirely normal on the basis of specificity, negative cooperativity, affinity, concentration, and interaction with antiinsulin receptor antibodies. These findings suggest the presence of an intracellular defect as the cause of the observed insulin resistance.

Acanthosis Nigricans↗
PubMed1978

The evolving clinical course of patients with insulin receptor autoantibodies: spontaneous remission or receptor proliferation with hypoglycemia.

Three patients with insulin resistance caused by autoantibodies to the insulin receptor were investigated serially over a 3-yr period. Major changes in carbohydrate metabolism, insulin receptor status, and titer of antireceptor antibodies were observed in each case. In one patient, normalization of glucose tolerance, insulin sensitivity, and receptor binding were associated with a spontaneous fall in the titer of antireceptor antibody. A second, more severely affected patient had two entirely distinct phase to her illness. The first, or hyperglycemic phase, was characterized by insulin resistance, negligible insulin binding to receptors on circulating monocytes, and high titers of circulating antireceptor antibodies. The second phase was characterized by refractory hypoglycemia, in association with proliferation of membrance insulin receptors; these occurred despite persistence of high titers of antireceptor antibody. An unusual heptic lesion, diffuse adenomatosis, was observed during this phase. A third patient showed features of both of the other patients, with spontaneous fall in antibody titer as well as a later phase of receptor proliferation. These studies demonstrate that patients with antibodies to insulin receptors may have a fluctuating clinical course. There may be spontaneous changes in antibody titers as well as independent changes in receptor concentration. Hypoglycemia and hepatic proliferation are newly recognized clinical sequelae in patients with this syndrome.

Adult↗
PubMed1977

Change in affinity of insulin receptors following oral glucose in normal adults.

125I-insulin binding to circulating monocytes has been studied in 4 normal volunteers in the basal state as well as at 2 and 5 hours after ingestion of 100 g of glucose. In each study five hours after glucose ingestion, the competition-inhibition curve was shifted to the left and was steeper than that in the basal study; the amount of insulin that caused a 50% decrease in specific binding of 125I-insulin in the basal study was 3-11 fold higher than at 5 hours after glucose. These changes in binding after glucose ingestion were largely due to major alterations of receptor affinity. We conclude that acute changes in receptor affinity occur normally as part of the physiologic regulation of target cell sensitivity to hormonal stimulation.

Adult↗
PubMed1976

[Clinical and metabolic aspects of juvenile myocardial infarct].

A clinical and metabolic study of 61 patients with myoocardial infarct before the age of 40 yr showed a high frequency of familial involvement, particularly in subjects with type IIA and IIB hyperbetalipoproteinaemia. Excess weight and arterial hypertension were rare, while premonitory angina was absent in 59%. Four subjects were diabetic. Oral glucose tolerance was normal in 14 and of diabetic type in 26 of 40 patients examined; the insulin response pointed to insulin-resistance. Dyslipidaemia was noted in 45%, including type IIA and IIB hyperbetalipoproteinaemia in 27%. Distribution of the frequency of infarct in function of cholesterolaemia classes gave a bimodal curve indicative of distinct normo- and hypercholesterolaemic groups within the series. Reduced glucose tolerance was more frequent in patients with low blood cholesterol. This suggests that reduced tolerance and high blood cholesterol are independent risk factors in coronary disease. No relation between the clinical and metabolic data could be ascertained.

Adult↗
PubMed1976

Suppression and stimulation mechanisms controlling glucagon secretion in a case of islet-cell tumor producing glucagon, insulin, and gastrin.

The mechanisms controlling secretion of glucagon and other pancreatic hormones were studied in a patient affected with multihormone-secreting islet-cell tumor. Fasting glucagon levels (3,000 pg./ml.) rose to 10 ng./ml. following arginine stimulation. While oral glucose load and intravenous glucose infusion did not suppress glucagon secretion, insulin administration induced a prompt depression in glucagon levels. Glucagon, insulin, and gastrin levels were suppressed by somatostatin while calcium infusion caused a paradoxical increase. It is suggested that only some of the stimulation-inhibition mechanisms were conserved in this case of glucagon-secreting pancreatic tumor.

Arginine↗
PubMed1976

Hormonal counterregulation in ethanol-induced hypoglycemia-Glucagon and cortisol secretion in pigs.

Plasma glucagon and cortisol levels were determined in pigs during ethanol-induced hypoglycemia. This hypoglycemia is due to an inhibition of gluconeogenesis which could be related to an abnormal secretion of gluconeogenetic hormones. In six pigs the infusion of ethanol for seven hours (6 mg/kg/min) induced a significant decrease of plasma glucose which was associated with a significant increase of plasma glucagon in the portal vein, femoral artery and hepatic vein. Corresponding with the period of maximal hypoglycemia, plasma cortisol in the femoral artery was also significantly increased. On the other hand, plasma insulin levels were consistently reduced during hypoglycemia. In a second group of six pigs ethanol was infused along with a glucose infusion (3 mg/kg/min) in order to obtain a relatively constant glucose concentration. In this group ethanol did not produce any significant modification of plasma glucagon and cortisol. Therefore, glucagon and cortisol hypersecretion is related to hypoglycemia induced by ethanol. Both the increase in plasma glucagon and cortisol and the decrease in plasma insulin could represent a protective mechanism against alcohol-hypoglycemia.

Animals↗
PubMed1976

Tryptophan metabolism "via" nicotimic acid in patients with scleroderma.

The tryptophan metabolism "via" kynurenine was studied in five patients with scleroderma after aminoacid loading. Four of these patients had abnormal tryptophan metabolism, characterized by a large urinary excretion of kynurenine and kynurenic acid in two cases, of kynurenine, 3-hydroxykynurenine and kynurenic acid in one case and of 3-hydroxyanthranilic acid in another case and generally a reduced excretion of xanthurenic acid and its 8-methyl ether in comparison with a group of healthy controls. Only two of the four patients had a normal response to tryptophan loading after pyridoxine administration, while no one of these responded to nicotinamide supplementation. But the simultaneous administration of pyridoxine and nicotinamide to three of these patients normalized the excretory picture after tryptophan loading. This suggested the presence of a combined vitamin deficiency in seleroderma. As four out of five patients showed total excretory values of kynurenine, kynurenic acid and acetylkynurenine higher than that of the controls, the sum of these values might be considered as a characteristic index of scleroderma.

Adult↗
PubMed1976

Hypolipidemic effects of metformin in hyperprebetalipoproteinemia.

Metformin's hypolipidemic effects (2.55 g/day for 3 months) have been studied in 19 subjects with Fredrickson's Type IV hyperprebetalipoproteinemia. The majority of patients were above ideal body weight (relative body weight = 118 +/- 2.7 %). Eleven of the subjects presented chemical diabetes, 5 fasting hyperglycemia, and 3 normal glucose tolerance. After treatment with metformin, body weight showed a slight, but significant reduction (--2.4 +/- 0.3 kg). Glucose tolerence was not substantially altered while basal glucose was significantly reduced in the 5 subjects with fasting hyperglycemia. Basal plasma insulin was significantly reduced in all the patients following metformin treatment. Insulin response to OGTT was slightly reduced in the subjects with fasting hyperglycemia. Independent of the patients' glucose tolerance, metformin treatment induced a marked decrease in plasma triglycerides (-- 40 %) and a reduction in plasma cholesterol (-- 12 %). No correlation was found between triglyceride and cholesterol reduction and body weight, glucose, and plasma insulin variations. Like phenformin, metformin acts not only on glucose metabolism and insulin secretion but on lipid metabolism as well.

Adult↗
PubMed1975

Glucagon secretion in primary endogenous hypertriglyceridemia before and after clofibrate treatment.

Arginine-induced insulin and glucagon secretion preceding and following clofibrate treatment was studied in 13 patients with endogenous hypertriglyceridemia. A positive correlation was demonstrated between fasting insulin and triglyceride levels and between the fasting insulin/glucagon molar ratio and triglyceride levels. In patients with endogenous hypertriglyceridemia, anginine infusion induced a significantly increased glucagon response with respect to that found in controls. No correlation was found to exist between glucagon and free fatty acids (FFA) or between glucagon and triglyceride levels. The same lack of correlation was found in normal subjects rendered hypertriglyceridemic by means of Intralipid infusion, which did not modify the fasting glucagon-like immunoreactivity (GLI) or the GLI response to arginine. Clofibrate treatment induces a triglyceride reduction (incrementTG) which is correlated with the reduction in the insulin/glucagon molar ration (incrementI/G). After clofibrate treatment there is also a significant reduction in fasting GLI levels and in the insulin response to arginine, and an increase in the glucagon response. Clofibrate could exercise its hypolipidemic effect by modifying the relationship between insulin and glucagon levels.

Adult↗
PubMed1975

The influence of plasma triglycerides on human growth hormone response to arginine and insulin: a study in hyperlipemics and normal subjects.

Human growth hormone (HGH) response to arginine (25 gm IV in 30 min) and to insulin (0.1 U/kg B.W.) was studied in 12 male patients (mean age 36 +/- 2 years), with normal glucose tolerance and normal body weight, affected with Fredrickson's Type IV primary hyperlipemia. The patients were examined both when plasma triglycerides (TG) were elevated and following clofibrate (2 gm/die for 30-60 days) induced TG reduction. No variations in glucose or FFA behaviour or in body weight were observed after clofibrate. HGH response to arginine was absent, while that to insulin was only inhibited, when plasma TG were elevated. A significant increase in HGH peaks after arginine (from 1.99 +/- 0.59 to 9.34 +/- 1.58 ng/ml) and a slight increment in HGH peaks after insulin (from 23.09 +/- 7.19 to 31.46 +/- 7.95 ng/ml) were observed following reduction in plasma TG. Arginine test was carried out in 7 normal subjects during saline infusion and at the 3rd hour of lipid infusion (Intralipid 20%). HGH response to arginine was absent in all of the subjects during lipid infusion. The HGH response to insulin test, carried out in 9 other normal subjects during saline infusion and at the 3rd hour of lipid infusion (Lipiphysan 15%) was significantly inhibited during lipid infusion. Since lipid infusion provoked an increment, not only in plasma TG but also in FFA, the inhibition of HGH release could be correlated with the elevated plasma levels of both TG and FFA. The results obtained in both spontaneous and experimental hyperlipemia not only confirm the role played by FFA in the regulation of HGH secretion, but also support the hypothesis that elevated TG levels could inhibit HGH response to some stimuli.

Adult↗
PubMed1975

Human growth hormone and cortisol response to insulin stimulation in aging.

The influence of age on plasma growth hormone (HGH) and cortisol response to i.v. insulin (0.1 U/kg of body weight) was evaluated in 32 healthy subjects whose ages ranged between 20 and 84 years. A significant reduction in HGH response to insulin was observed with aging. In the young (20-34 years), middel-aged (35-49 years), and elderly (53-84 years) groups, average HGH peaks were 46.51 +/- 7.37, 29.95 +/- 5.35, and 14.31 +/- 2.39 ng/ml while average HGH areas were 2.911 +/- 0.484, 1.654 +/- 0.316, and 0.699 +/- 0.149 mug-min, respectively. Since insulin's hypoglycemic effect became less rapid with aging, this could, in part, explain the progressive decline in the HGH response to insulin. This phenomen may also be attributed to histological changes occurring in the pituitary with aging. Moreover, cortisol response was similar to all three age groups. These findings suggest that, while HGH response to insulin is correlated with age, adrenal response does not show any important modifications with aging.

Adult↗
PubMed1975

Relationship between tryptophan metabolism and vitamin B6 and nicotinamide in aged subjects.

The urinary excretion of tryptophan metabolites was studied in 20 aged subjects (over 70 years) after oral tryptophan loading (100 mg/kg body weight). All the subjects considered showed an abnormal excretion of metabolites with mean values of 24.67% in men and 25.83% in women in comparison to 6.77% in young controls. Among the metabolites the highest excretion was from kynurenine; moreover kynurenic acid and N-alpha-acetylkynurenine were also excreted in signficantly high amounts. The other metabolites too showed increased values. As the abnormal tryptophan metabolism in aging seemed to be in connection with vitamin B6 and nicotinamide, in a group of 7 aged sugjects the urinary excretion of tryptophan metabolites was studied after aminoacid loading with or without simultaneous administration of these two vitamins. The results show that the abnormal excretory pattern is normalized after vitamin administration (from 16.49% to 7.42% total mean metabolite values).

Adult↗