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R Zini

Publications and source records attributed to R Zini.

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

Low glucocorticoid concentrations decrease oxidative phosphorylation of isolated rat brain mitochondria: an additional effect of dexamethasone.

The effects of hydrocortisone, triamcinolone, prednisolone and dexamethasone have been investigated in vitro using mitochondria isolated from rat brain. Respiratory control ratio (RCR), oxygen consumption, ATP synthesis, enzymatic activities of involved complexes and superoxide anion generation have been measured to assess the effects of these drugs. Our data showed that the decrease of RCR induced by glucocorticoids was due to a common inhibition of oxidative phosphorylation (State 3) and of complex V activity and a modification of the proton-fluxes through the mitochondrial inner membrane. These effects were quantitatively limited, since they occurred at concentrations lower than 2 nM. Dexamethasone was the only one able to induce a specific inhibition of complex I activity and to decrease the superoxide anion radical generation. Inhibition of complex V and partial reversion of uncoupling seem to be common properties of glucocorticoids. The theoretical consequence of these inhibitions could be the modulation of the mitochondrial function, oxygen consumption rate, ATP synthase activity and superoxide anion radical production, involved in many patho-physiological phenomena.

Animals↗
PubMedDate not supplied

Thermodynamic study of iodocyanopindolol beta-adrenoceptors interactions with rat lung and cerebral cortex.

(+/-)125 I-cyanopindolol ((+/-) I CYP) was used to characterize beta-adrenoceptors on rat lung and cerebral cortex membranes. The affinity of (+/-) ICYP was higher for lung (Kd = 64.3 pM) at 37 degrees C. The association reaction of (+/-) ICYP was faster with lung (k+1 = 1.52 X 10(9) M-1.min-1) than with cerebral cortex beta-adrenoceptors (k+1 = 1.75 X 10(8) M-1.min-1). In both tissues, the dissociation reaction followed a biphasic process with a fast (t 1/2 = 15.4 min and 5.6 min for lung and cerebral cortex respectively) and a slow component (t 1/2 = 474 min and 255 min for lung and cerebral cortex respectively). The thermodynamic parameters for (+/-) ICYP - beta-adrenoceptors binding have been determined from kinetics and equilibrium studies, for the two tissues, at several temperatures between 0 degrees and 44 degrees C. For lung and cerebral cortex, Arrhenius plots were linear with different energies of activation. Van't Hoff plot was not linear for lung and the standard enthalpy and entropy changes of (+/-) ICYP - beta-adrenoceptors interaction decreased linearly with temperature: the binding occurred with a negative heat capacity change (delta Cp degrees = -368.9 cal. moles-1.K-1) at 25 degrees C. Thermodynamic and kinetic results show that binding of (+/-) ICYP to lung beta-adrenoceptors could involve two successive equilibria with a conformational change of the beta-adrenergic receptor.

Animals↗
PubMedDate not supplied

[Transvaginal sonography as a screening method for the identification of patients at risk of postmenopausal endometrial pathology].

Starting from the anatomopathological assumption that endometrial thickness in postmenopausal women never exceeds 3 mm, and in view of the reliability of measurements made using an echographic probe, the authors evaluated the value of transvaginosonography (TVS) as a mass screening method for postmenopausal endometrial pathologies. A group of 74 patients were examined who were recruited from those attending the out-patient menopause clinic. All subjects conformed to the following admission criteria: amenorrhea for the past two years; absence of oestroprogestin therapy for at least six months; absence of vaginal blood loss. A 5 MHz probe was used to measure maximum endometrial thickness on the longitudinal plane; values were divided by two if the surfaces were adjacent. Patients were monitored according to the following protocol: endometrial thickness under 1 mm control every 12 months; thickness between 1-3 mm--control every 3 months; thickness equal to or over 4 mm--hysteroscopy, targeted biopsy, possible scraping and TVS control after 3 months. The group was subdivided as follows: 65 patients (87.8%) were without risk; 3 patients (4%) belonged to the intermediate risk group; 6 patients (8.2%) belonged to the high risk group. Of the latter, 4 revealed an endometrial polyp, one presented uterine polymyomatosis and one a proliferative-type endometrium. The authors' experience is still limited but the absence of false positives encourages them to continue their research using this simple and well tolerated method. It might represent a valid alternative to hysteroscopy as a screening method in the asymptomatic population at risk for endometrial carcinoma.

Biopsy↗