Search PubMed⌕ Search

Biomedical subjects

G Gelmini

Publications and source records attributed to G Gelmini.

At least 19 recordsLinked to original sources
PubMed2000

Unstable superheavy relic particles as a source of neutrinos responsible for ultrahigh-energy cosmic rays

Decays of superheavy relic particles may produce extremely energetic neutrinos. Their annihilations on the relic neutrinos can be the origin of the cosmic rays with energies beyond the Greisen-Zatsepin-Kuzmin cutoff. The redshift acts as a cosmological filter selecting the sources at some particular value z(e)+/-deltaz, for which the present neutrino energy is close to the Z pole of the annihilation cross section. We predict no directional correlation of the ultrahigh-energy cosmic rays with the galactic halo. At the same time, there can be some directional correlations in the data, reflecting the distribution of matter at redshift z = z(e)+/-deltaz. Both of these features are manifest in the existing data. Our scenario is consistent with the neutrino mass reported by super-Kamiokande and requires no lepton asymmetry or clustering of the background neutrinos.

Journal Article↗
PubMed1996

Left ventricular diastolic function during adrenergic stress in essential hypertension: acute and chronic effects of ACE inhibition.

We studied the changes in left ventricular (LV) diastolic function induced by angiotensin-converting enzyme (ACE) inhibition at rest and during adrenergic stimulation and their relation to blood pressure (BP) variations to determine whether reductions in the renin-angiotensin system may improve diastolic function irrespective of BP reduction. Echocardiographic indices of systolic and diastolic function, plasma catecholamines as estimated by high-pressure liquid chromatography, and BP variations (Dynamap) were determined at rest and during the cold pressor test (CPT) before and 6 hours and 20 days after ACE inhibition (lisinopril), 20 mg/day by mouth in 10 subjects with uncomplicated essential hypertension. Blood Pressure was significantly reduced after both 6 hours and 20 days of therapy. The cold pressor test induced similar increases in BP in both basal conditions and after acute and chronic treatment. Catecholamine levels were unchanged by the therapy. Systolic function, evaluated by fractional shortening, ejection fraction, and systolic dV/dt, was normal and unchanged during CPT and after treatment. Diastolic function, assessed by volume curve analysis, showed a reduced percentage contribution of rapid filling to total diastolic filling, an increase in the contribution of the atrial systole, and an increase in the isovolumetric relaxation time. During CPT these parameters deteriorated further in response to increased afterload. Lisinopril therapy induced significant increases in end-diastolic volume (p < 0.005) with a progressive increase in the rapid filling dV/dt (p < 0.005 at rest; p < 0.001 during CPT) and a reduction in isovolumetric relaxation (p < 0.0001 at rest and p < 0.01 during CPT). The correlation between systolic BP (afterload) and the rapid filling dV/dt, both at rest and during CPT, was modified by treatment with the ACE inhibitor, with significantly higher rapid filling dV/dt values, and with the pressure loads equal (reduction of the slope and rightward shift of the correlation line). The improvement in diastolic function achieved by ACE inhibition at rest and during CPT appears unrelated to plasma catecholamines and only partly ascribable to the reduced pressure load. The tissue angiotensin II reduction might by itself improve the myocardial response to the pressure load and adrenergic stimulation.

Adult↗
PubMed1989

Effects of ovariectomy on blood and plasma viscosity, fibrinogen and whole blood filterability.

Blood and plasma viscosity, fibrinogen concentrations and whole blood filterability (VB) were evaluated before surgery and 7 and 30 days postoperatively in 2 groups of subjects, one of which comprised 10 hysterectomized women and the other 14 women who had undergone both hysterectomy and ovariectomy. Oestrogens and various metabolic haematological parameters were measured and correlated with the haemorrheological data. By day 7 after surgery fibrinogen concentrations and plasma viscosity had increased, while VB had decreased. Plasma viscosity and fibrinogen levels correlated negatively with VB in the non-ovariectomized women. Three weeks later almost complete normalization of all parameters was observed in all of the subjects, except for the persistence of low oestrogen concentrations and a further decrease in VB values in the ovariectomized patients, these parameters showing a positive correlation. This study demonstrates that haemorrheological alterations occur after hysterectomy (with or without ovariectomy) in the early post-operative period. The striking decrease in VB values and its correlation with the oestrogen concentrations observed 1 mth after ovariectomy suggest that the fall in oestrogen levels might be responsible for the decrease in whole blood filterability.

Adult↗
PubMed1989

[Etiopathogenetic role of metabolic, circulatory, sex factors and type and duration of diabetes in diabetic retinopathy. Investigation with vitreofluorophotometry].

We have studied metabolic, circulatory and vascular parameters in a group of 57 diabetics (37 affected by IDDM, 20 affected by NIDDM; 35 were males, 22 were females). Goals of present study were: 1) quantitative evaluation of the blood retinal barrier; 2) influence of the metabolic state, blood pressure, sex, type and duration of the diabetes on the ocular conditions; 3) relationship between ophthalmoscopic appearance of the retina and vitreous fluorophotometric recordings. We concluded that: a) ocular alterations depend by lipidic metabolism, blood pressure, sex, type and duration of the diabetes; b) vitreous fluorophotometry has proved a good device for early detection of retinal damages in the diabetic retinopathy.

Blood Pressure↗
PubMed1988

Hepatic alterations in indomethacin-treated rabbits.

Indomethacin was parenterally administered (6 mg/Kg/day) for 30 days to rabbits, to evaluate changes in serum biochemical parameters and any ultrastructural alterations induced by the drug at the hepatic level. An analysis of the results demonstrated that when the group of rabbits, a statistically significant increase in the serum ALT was found in the treated rabbits. Ultrastructural observations showed the following hepatocyte alterations: 1) minimum mitochondrial alterations 2) mild signs of cholestasis (pericanalicular osmophilic bodies) 3) Smooth endoplasmic reticulum hyperplasia. These findings suggest that indomethacin has the capacity to induce hepatic lesions in the rabbit and this is probably due to the surfactant mechanism.

Alanine Transaminase↗
PubMed1988

Oxytocin response to insulin-induced hypoglycemia in obese subjects before and after weight loss.

The response of plasma oxytocin to an iv bolus injection of crystalline insulin (0.15 U/kg) was evaluated in 14 normal weight [mean body mass index (BMI) = 23] and in 9 obese (mean BMI = 42) men. Similar blood glucose decrements after insulin injection were observed in the two groups. Obese and normal weight subjects presented similar basal oxytocin levels. In both groups, oxytocin rose significantly during the insulin tolerance test (ITT); however, the peak oxytocin response in the obese men was significantly lower than in the normal weight subjects. Obese men were restudied after substantial weight loss. Basal oxytocin levels and glucose response to insulin did not change after weight reduction. The oxytocin response to the ITT was significantly higher than before slimming and did not differ from that observed in the normal weight subjects. A significant negative correlation between BMI values and oxytocin peak levels during ITT was observed in the lean controls and obese subjects (r = 0.516, p less than 0.02). These results demonstrate that in obese subjects the oxytocin secretory response during an insulin tolerance test is reduced, suggesting the existence of a hypothalamic-pituitary disorder in obesity.

Adult↗
PubMed1987

Evaluation of erythrocyte deformability in pre-menopausal and post-menopausal women.

Whole blood filterability expressed as volume of red blood cells filtered per minute (VRBC) was evaluated in 10 pre-menopausal and 10 post-menopausal women. In addition, blood concentrations of total and high-density lipoprotein (HDL), cholesterol, triglycerides, uric acid, fasting glucose and fibrinogen were measured and correlated with VRBC values. Whole blood filterability was significantly lower in the post-menopausal than in the pre-menopausal women. All the other parameters examined were higher after the menopause, except for HDL-cholesterol levels, which were found to be lower. The VRBC values correlated strongly with fibrinogen, triglyceride and HDL concentrations. These findings indicate that the higher plasma fibrinogen and triglyceride concentrations and the lower HDL-cholesterol levels observed in women after the menopause might be associated with haemorrheological changes. These might be partly responsible for the increased incidence of cardiovascular diseases in post-menopausal women.

Adult↗
PubMed1987

Nicotinic and M1-, M2-muscarinic cholinergic control of ACTH response to insulin-induced hypoglycaemia in man.

The possible mediation of muscarinic and/or nicotinic-cholinergic receptors in the response of ACTH to insulin-induced hypoglycaemia was evaluated in 18 normal men. Subjects were tested with the insulin (0.15 U/kg) tolerance test (ITT) in basal conditions and in the presence of the M1- and M2-muscarinic antagonist atropine (600 micrograms iv just before insulin injection (time 0) plus 600 micrograms 20 min later in 6 subjects) or the M1-muscarinic receptor blocker pirenzepine (40 mg iv 10 min before ITT or 20 mg at time 0 plus 30 mg at time 20 in 6 subjects). The remaining 6 men were treated with the nicotinic receptor antagonist trimethaphan (0.3 mg/min x 30 min before ITT). ACTH rose 4.7 times in response to hypoglycaemia. The ACTH response to hypoglycaemia did not change after pirenzepine administration, whereas it was significantly increased by atropine and decreased by trimethaphan treatment. These data indicate that nicotinic and muscarinic (M2 but not M1) receptors participate in a different manner in the regulation of the hypoglycaemia-induced ACTH release.

Adrenocorticotropic Hormone↗