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Biomedical subjects

A Valerio

Publications and source records attributed to A Valerio.

101 records · Page 6Linked to original sources
PubMedDate not supplied

Bromocriptine acute effect on insulin, glucagon and growth hormone levels in acromegalic patients.

It has been shown that L-dopa or dopamine administration influences glucose metabolism, as well as insulin and glucagon release in man. In the present study, the effect of bromocriptine (CB-154), a long-acting dopamine agonist, on insulin, glucagon and growth hormone secretion in 32 acromegalic patients was investigated. Glucose, insulin and plasma glucagon levels were not modified following administration of bromocriptine or placebo. Moreover, plasma GH levels were decreased by more than 50% in 18 of the 32 acromegalics. Mean GH levels were significantly lower with respect to levels observed following placebo at 60 min to the end of the test (p less than 0.001). Administration of a double dose of CB-154 (5 mg po) one hour before arginine test did not affect insulin or glucagon secretion with respect to levels observed during arginine alone. In addition, there was a fall in GH levels similar to that observed following administration of bromocriptine alone. These findings suggest that bromocriptine in itself does not exert a direct action on insulin and glucagon release. Improvement in glucose tolerance and reduction in insulin secretion observed following prolonged CB-154 treatment in acromegalic patients are probably due to a simultaneous inhibition of GH secretion or to other peripheral effects of bromocriptine.

Acromegaly↗
PubMedDate not supplied

Dopamine D2, D3, and D4 receptor mRNA levels in rat brain and pituitary during aging.

Reverse Transcriptase-Polymerase Chain Reaction technique was used to determine the levels of the mRNAs encoding different receptors belonging to the D2 family in various brain areas of 6-, 12-, 18-, and 24-month-old rats. We found a progressive, age-dependent reduction in the mRNA levels of D2 short and D2 long receptors in corpus striatum, substantia nigra, and frontal cortex. D2 short and D2 long receptor mRNA levels were unchanged in hippocampus and olfactory tubercle, while they increased in pituitary. D3 receptor mRNA levels were reduced in olfactory tubercle and unchanged in striatum. D4 receptor mRNA levels were unmodified in pituitary gland. These data suggest that the molecular mechanisms responsible for regulating the pattern of expression of the various dopamine receptors are differentially regulated by aging.

Aging↗
PubMedDate not supplied

Type I insulin-dependent diabetic patients show an impaired renal hemodynamic response to protein intake.

Human kidney responds to a meat meal with an increase in glomerular filtration rate (GFR), but the mechanisms regulating kidney hemodynamics following protein intake are poorly understood in Type I insulin-dependent diabetes. In the present study we investigated GFR response to protein intake (600 gr/1.73 m2 meat meal) in nine normal subjects and 21 Type I insulin-dependent diabetic patients with normal albumin excretion rates as well as proximal tubular sodium reabsorption rates and distal sodium delivery (PRNa and DDNa). The same study was reperformed in normal subjects and diabetic patients, with less than a 5 year diabetes duration, following one week of indomethacin treatment. Normal subjects showed a 38% increase in GFR following protein intake, whereas diabetic patients showed a significantly lower response (18%, p less than 0.01). The response of GFR to protein challenge was negatively related to diabetes duration but not to baseline glomerular filtration rate. Indomethacin treatment completely prevented the protein induced GFR increase in normal subjects but not in diabetic patients. Sodium reabsorption rate was increased following protein challenge both at the proximal and distal tubular level, as was net natriuresis.(ABSTRACT TRUNCATED AT 250 WORDS)

Diabetes Mellitus, Type 1↗
PubMedDate not supplied

Effect of metformin on insulin-stimulated glucose turnover and insulin binding to receptors in type II diabetes.

Euglycemic insulin glucose-clamp and insulin-binding studies on erythrocytes and monocytes were performed in seven type II (non-insulin-dependent) diabetic subjects before and after 4 wk of metformin treatment (850 mg 3 times/day) and in five obese subjects with normal glucose tolerance. Glucose turnover was also measured at basal insulin concentrations and during hyperinsulinemic euglycemic clamps. During euglycemic insulin-glucose clamps, diabetic subjects showed glucose disposal rates of 3.44 +/- 0.42 and 7.34 +/- 0.34 mg X kg-1 X min-1 (means +/- SD) before metformin at insulin infusion rates of 0.80 and 15.37 mU X kg-1 X min-1, respectively. With the same insulin infusion rates, glucose disposal was 4.94 +/- 0.55 (P less than .01) and 8.99 +/- 0.66 (P less than .01), respectively, after metformin treatment. Glucose disposal rates in normal obese subjects were 5.76 +/- 0.63 (P less than .01) and 10.92 +/- 1.11 (P less than .01) at 0.80 and 15.37 mU X kg-1 X min-1, respectively. Insulin maximum binding to erythrocytes in diabetics was 9.6 +/- 4.2 and 5.8 +/- 2.6 X 10(9) cells (means +/- SD) before and after metformin treatment, respectively (NS). Insulin maximum binding to monocytes in diabetics was 6.2 +/- 2.3 X 10(7) cells before and 5.0 +/- 1.6% after metformin. Hepatic glucose production was higher in the diabetic patients at basal insulin levels, but not at higher insulin concentrations, and was not significantly changed by drug treatment. Basal glucose and insulin concentrations decreased with metformin. Thus, metformin treatment improved glucose disposal rate without significant effect on insulin-binding capacity on circulating cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Resection in chronic pancreatitis: anastomosis with the jejunum or with the stomach?

Even in centers where the first choice in the surgical treatment of chronic pancreatitis is a derivative procedure some selected patients require resection. The most popular solution of gastrointestinal reconstruction still seems to be pancreaticojejunostomy but, the review of the reported experiences, suggests a general trend towards anastomosis with the stomach as a recent policy. A reliable comparison between pancreaticogastrostomy and pancreaticojejunostomy is difficult because the reported series are seldom related to chronic pancreatitis patients only, but are reporting mixed date concerning mainly periampullary cancer. Moreover with only one exception no prospective randomised clinical trails are available; unfortunately the positive trend in favour of pancreaticogastrostomy reported in uncontrolled studies is not confirmed in the randomized setting. Also the comparison between the experiences achieved by the present authors working in centers with different approach to the pancreatic anastomosis does not show statistical significant difference for both morbidity and mortality. In conclusion nowadays the best confidence and experience with any of the two methods represents the basis of choice.

Anastomosis, Surgical↗
PubMedDate not supplied

[Effects of ticlopidine on platelet function at rest and after exercise in patients with previous myocardial infarct. An acute crossover double-blind study].

The effects of Ticlopidine on platelet function at rest and after exercise test in 12 patients with a history of myocardial infarction but no risk factors and/or residual angina, were investigated. The patients were treated with 500 mg per diem Ticlopidine or placebo for 15 days in a crossover double-blind study. Blood samples were taken before and 3 minutes after maximum effort exercise cycle tests. Blood samples from 25 healthy volunteers of comparable age and sex were used for control purposes. The parameters examined were: platelet aggregation induced by ADP (1 and 3 mumol/l), Arachidonic Acid (AA) (1.3 mmol/l) and collagen (2 micrograms/ml); the presence of circulating platelet aggregates and plasmatic fibrinogen levels. When compared with the controls, the patients showed higher levels of aggregation caused by ADP, AA and collagen as well as circulating aggregates. Exercise produced a statistically significant increase in platelet activation, while Ticlopidine significantly inhibited the platelet aggregation induced by ADP, AA and collagen as well as circulating aggregates both at rest and after the exercise test. Fibrinogen levels were higher in the heart attack patients than the controls especially after exercise, but not to a statistically significant degree. Treatment with Ticlopidine did not influence plasma fibrinogen levels. It is not known whether the patients with signs of effort-induced platelet aggregation run a higher risk of ischaemic cardiopathy or whether drug treatment could prevent this eventuality.

Adult↗
PubMedDate not supplied

[Pheochromocytoma].

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Adolescent↗