Search PubMed⌕ Search

Biomedical subjects

A Belloni

Publications and source records attributed to A Belloni.

44 records · Page 3Linked to original sources
PubMed1994

Gene expression, localization, and characterization of endothelin A and B receptors in the human adrenal cortex.

Compelling evidence indicates that the endothelium-derived potent vasoconstrictor endothelin-1 (ET-1) stimulates aldosterone secretion by interacting with specific receptors. Although two different ET-1 receptors have been identified and cloned, the receptor subtype involved in mediating aldosterone secretion is still unknown. Accordingly, we wished to investigate whether the genes of ET-1 and of its receptors A and B are expressed in the normal human adrenal cortex. We designed specific primers for ET-1 and the ETA and ETB receptors genes and developed a reverse transcription polymerase chain reaction (RT-PCR) with chemiluminescent quantitation of the cDNA. In addition, we carried out 125I ET-1 displacement studies with cold ET-1, ET-3 and the specific ETA and ETB ligands BQ123 and sarafotoxin 6C. Localization of each receptor subtype was also investigated by autoradiography. Binding experiments were first individually analyzed by Scatchard and Hofstee plot and then coanalyzed by the nonlinear iterative curve fitting program Ligand. Histologically normal adrenal cortex tissue, obtained from kidney cancer patients (n = 7), and an aldosterone-producing adenoma (APA), which is histogenetically derived from the zona glomerulosa (ZG) cells, were studied. Results showed that the ET-1, ETA and ETB mRNA can be detected by RT-PCR in all adrenal cortices as well as in the APA. The best fitting of the 125I ET-1 displacement binding data was consistently provided by a two-site model both in the normal adrenal cortex (F = 22.1, P < 0.0001) and in the APA (F = 18.4, P < 0.0001). In the former the density (Bmax) of the ETA and ETB subtype was 2.6 +/- 0.5 pmol/mg protein (m +/- SEM) and 1.19 +/- 0.6, respectively. The dissociation constant (Kd) of ET-1, ET-3, S6C, and BQ-123 for each receptor subtype resulted to be within the range reported for human tissue for the ETA and ETB receptors. In the APA tissue the Bmax tended to be lower (1.33 and 0.8 pmol/mg protein, for the ETA and ETB, respectively) but the Kd were similar. Autoradiographic studies confirmed the presence of both receptor subtypes on the ZG as well as on APA cells. Thus, the genes of ET-1 and both its receptor subtypes ETA and ETB are actively transcribed in the human adrenal cortex. Furthermore, both receptor subtypes are translated into proteins in ZG and APA cells.

Adrenal Cortex↗
PubMed1990

Beta-TG and plasma catecholamines levels after sympathetic stimuli in hypertensives and patients with peripheral vascular disease.

The influence of the sympathetic nervous system on platelet functions in vivo is still controversial. The aims of our study were to compare the response to various sympathetic stimuli in normal subjects and in patients with essential hypertension (HT) or peripheral vascular disease (PVD) and to evaluate any correlations among plasma levels of catecholamines, beta-thromboglobulin (beta-TG) and platelet factor 4 (PF4). In basal conditions beta-TG and PF4 values in the HT patients were higher than those observed in the controls of the same age but lower than those of the PVD patients. Although the different sympathetic stimuli (90 degrees tilting, handgrip, treadmill test, bicycle test) caused a significant increase of the plasma epinephrine (E) and norepinephrine (NE) levels, they did not modify the beta-TG and PF4 levels in any of the groups studied. The platelet activation indices, therefore, regardless of the basal values, do not seem to be influenced by sympathetic stimulation.

Adult↗
PubMed1990

Ticlopidine prevents renal disease progression in rats with reduced renal mass.

Functional and morphological studies were done in three groups of male Sprague-Dawley rats after removal of the right kidney and infarction of approximately five-sixths of the left. Group 1 received no specific therapy. Group 2 was treated with ticlopidine, 150 mg/kg per os, for 50 days starting 10 days after surgical ablation. Group 3 was given the thromboxane antagonist, GR 32191, 3 mg/kg b.i.d. orally for 50 days, like ticlopidine. Untreated Group 1 rats developed renal insufficiency, systemic hypertension, progressive proteinuria and glomerulosclerosis. In Group 2 treatment with ticlopidine was associated with less severe impairment of renal function. Proteinuria was significantly lower and animals were partially protected from the development of glomerulosclerosis. These animals had significantly prolonged skin bleeding time. In vitro ADP and arachidonic acid (AA)-induced platelet aggregation was inhibited. Systemic blood pressure was significantly lower than in controls. In Group 3 rats GR 32191 failed to influence progressive proteinuria and severity of glomerulosclerosis which were comparable to those in Group 1. Bleeding time was not prolonged, and in vitro platelet aggregation was inhibited only when AA was used as aggregating agent. Systemic blood pressure was not influenced. These studies suggest that a drug like ticlopidine, which has a broad spectrum of pharmacological actions on platelets and platelet-cell interactions, does retard the development of progressive renal injury when nephron number is reduced. Specific blocking of thromboxane A2 (TxA2) biological activity does not influence progressive renal disease in rats with remnant kidney.

Animals↗
PubMed1990

Thromboxane receptor blockade attenuates the toxic effect of cyclosporine in experimental renal transplantation.

Renal dysfunction, manifested as a dose-dependent reduction in glomerular filtration rate (GFR), is a common complication of cyclosporine A (CyA) administration to laboratory animals and humans. We have recently shown that chronic CyA treatment in normal rats is associated with a selective increase in renal thromboxane A2 (TXA2) synthesis, which may play a role in GFR reduction. The present experiments were designed to investigate whether pharmacological inhibition of TXA2 activity could reduce CyA nephrotoxicity in a rat model of renal transplantation. To discriminate the possible biochemical changes due to rejection episodes from those due to CyA nephrotoxicity, we selected a model of renal isograft free of graft rejection processes. We demonstrated that oral CyA administration for 30 days to rats undergoing renal isograft is associated with the development of renal insufficiency, as indicated by a progressive increase in serum creatinine concentration and reduction in creatinine clearance. In the same animals, a parallel increase in the urinary excretion of TXB2 was found. Combination of the specific thromboxane receptor antagonist GR32191 with CyA treatment partially prevented the deterioration in renal function observed in animals given CyA alone, without modifying the urinary TXB2 excretion. In contrast, renal-isografted rats given GR32191 alone or vehicle alone for 30 days did not show any changes in serum creatinine, creatinine clearance, and urinary TXB2 excretion throughout the experimental period. Mild hypercellularity of the glomerular tuft was observed in isografted kidneys chronically exposed to either CyA or CyA plus GR32191.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Effects of sympathetic activation on ventricular ectopic beats in subjects with and without evidence of organic heart disease.

In a selected group of 10 apparently healthy subjects and 22 patients with organic heart disease, all with frequent ventricular ectopic beats on Holter monitoring, we assessed the influence of sympathetic activation by comparing the arrhythmogenic effects of a symptom-limited bicycle exercise stress test and 90 degree head up tilt. Tilting reduced ventricular arrhythmias in the normal subjects (-48 +/- 18% from 9 +/- 2 beats min-1, P less than 0.05). Exercise stress testing caused small and insignificant changes in arrhythmias during the early (50-75 W) phases and an almost complete suppression of ventricular ectopic beats in the final stages (-99 +/- 1%, P less than 0.01). In six of the 10 subjects, ventricular arrhythmias reappeared in the early recovery phase. In the 22 patients with organic heart disease, tilting increased ventricular ectopic beats (43 +/- 17% from 9 +/- 3 beats min-1, P less than 0.05); augmented repetitive forms in 12 patients (179 +/- 88% from 1.4 +/- 0.6 per 3 min) and produced repetitive forms in six of the 10 remaining patients who did not show repetitive forms during control conditions. Exercise stress testing caused a marked increase in ectopic activity in the early phase (84 +/- 35%) while the response during the maximal phase of exercise as well as during recovery was related to the effort capabilities. Arrhythmias were increased in 12 patients with limited exercise duration and were reduced in 10 patients with good exercise tolerance. These data indicate that sympathetic activation has different effects on ventricular arrhythmias depending on the clinical setting and that tilting is a useful maneuver to evaluate the arrhythmogenic effects of increased sympathetic activity.

Adult↗
PubMed1983

Value of two-dimensional echocardiography in the diagnosis of pericardial cysts.

Four adult patients with pericardial cysts were studied by two-dimensional echocardiography. In all cases echocardiography demonstrated a round echo-free structure, of varying size, related to one of the cardiac chambers, from which it was separated by a definite wall of echoes. M-mode echocardiography in the three cases in which it was performed, failed to yield the diagnosis. This report assesses the importance of two-dimensional echocardiography and its greater reliability and sensitivity compared with: (1) M-mode echo in identifying pericardial tumors and establishing their relationships to nearby cardiac structures, and (2) standard chest X-ray in differentiating solid masses from cysts and in defining the characteristics of cysts walls. Particular stress is laid on the role of two-dimensional echo cardiography leading directly to surgery in patient number 4, who had a teratoma and in whom early surgery was essential. The high sensitivity and the ability of the technique to differentiate solid from cystic masses and to define their relationships with cardiac chambers make it a reliable method for assessing pericardial cysts.

Adult↗
PubMed1981

[Juvenile hypertension. Results of a study in high school in Milan (author's transl)].

Blood pressure has been measured in a cohort of 2300 high school students of Milan (14-15 years old) for two years on end. The prevalence of "borderline hypertension" was 11.5% at the first examination and 8.5% at the second. The values of blood pressure were decreased, in every measurement, after a year from the initial screening especially in "borderline hypertensives". This study has confirmed that the "borderline hypertension" in subjects 14-15 aged is a transient phenomenon, but the incidence of "stable hypertension" as been found higher significantly in "borderline hypertensives" than normotensives. The results are discussed.

Adolescent↗