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Biomedical subjects

M Condorelli

Publications and source records attributed to M Condorelli.

At least 235 records · Page 13Linked to original sources
PubMed1982

Activation of human basophils by staphylococcal protein A. I. The role of cyclic AMP, arachidonic acid metabolites, microtubules and microfilaments.

Protein A from Staphylococcus aureus (Staph A) induces histamine secretion from human basophil leucocytes in the concentration range 10(-4) - 10 micrograms/ml. This reaction has great similarities to that of antigen or anti-IgE-induced release. It is characterized by a two stage reaction, requires extracellular calcium and is optimal at 37 degrees C. The rate of release is similar to that of IgE-mediated reactions. Histamine release induced by Staph A is inhibited by metabolic inhibitors, drugs which increase intracellular cyclic AMP levels, inhibitors of lipoxygenase pathways and a phospholipase A2 inhibitor. D2O and cytochalasin B which affect microtubules and microfilaments respectively, enhance histamine release induced by Staph A. These results suggest that Staph A-induced release is modulated by intracellular cyclic AMP, arachidonic acid metabolites, requires energy and is enhanced by the disruption of microfilaments and stabilization of microtubules.

Arachidonic Acids↗
PubMed1982

[Closed chest interruption of A-V conduction in the treatment of refractory supraventricular tachyarrhythmias. A clinical contribution].

The AA. describe a technique for interrupting the A-V conduction using a direct-current shock delivered from a cardioversion unit to the A-V junctional tissue by means of a conventional electrode-catheter. The method was used in 2 patients with refractory supraventricular tachycardias. After the procedure both patients received a programmable A-V sequential pacemaker. The first patient, with cardiomyopathy and intermittent W-P-W syndrome, had a 2-year history of iterative reciprocating tachycardia and occasional episodes of atrial flutter-fibrillation. The second patient, with coronary heart disease, had recurrent episodes of atrial flutter for at least 2 years. In patient 1 the shock caused a suprahisian first-degree block. Atrial pacing at 580 ms cycle length provoked a 2:1 block and ventricular pacing showed no retrograde conduction. The patient, who is not pacemaker-dependent, is now free from reciprocating tachycardia and, during atrial flutter-fibrillation episodes, the ventricular rate varies from 62 to 75 bpm. In patient 2 the shock caused a persistent complete A-V block and neither antegrade nor retrograde conduction was observed during atrial and ventricular pacing. During a long episode of atrial flutter, there was a complete A-V block with a ventricular rate between 40 and 48 bpm. The follow-up is 9 months in both patients. We conclude that the technique used, which does not require open heart surgery, can be effectively used in patients with disabling supraventricular tachyarrhythmias resistant to drug treatment.

Amiodarone↗
PubMed1982

[Mexiletine in the treatment of lidocaine-resistant ventricular tachycardia. Preliminary results].

Intravenous mexiletine (3 mg/Kg as bolus) was given to 7 patients with sustained ventricular tachycardia. Previous lidocaine administration in standard doses failed to suppress ventricular tachycardia. Mexiletine successfully suppressed the episodes of ventricular tachycardia in 6 of the 7 patients at a dose of 250 mg. Minimal non-cardiac toxicity occurred after mexiletine administration in the majority of patients. Mexiletine appears to be a promising alternative to lidocaine in the management of ventricular arrhythmias.

Drug Resistance↗
PubMed1981

His bundle electrogram recording using a multipolar electrode catheter via the arm veins.

In eighteen patients with atrioventricular conduction disturbance, His bundle electrograms were studied via the arm vein. A 6F Berkovits-Castellanos USCI hexapolar electrode catheter was introduced into the right atrium and looped across the tricuspid valve in a "golf club" shape. The main aim was to leave the two distal electrodes in contact with the atrial endocardium to perform atrial pacing, while displaying the other four electrodes along the superior angle of the tricuspid valve for proximal and distal His bundle recordings. His bundle electrograms were successfully obtained in all cases. The arm approach provides an alternate route whenever the femoral approach is not feasible. Moreover, the use of an hexapolar electrode catheter provides some practical advantages: 1) it enables atrial pacing to be performed, as well as proximal and distal His bundle recording to be obtained, by using the same multipolar electrode catheter; and 2) it allows long-term monitoring of His bundle potentials, in view of the stability of His bundle recordings. Finally, the arm approach could be the method of choice for the study of His bundle electrograms during leg supine exercise in selected patients.

Arm↗
PubMed1981

Development of cardiac hypertrophy in rats exposed to acute hypobaric hypoxia. - Studies with protein synthesis inhibitors.

The study is based on the experimental model of myocardial hypertrophy in rats. Male Sprague-Dawley adult rats were exposed to acute hypoxia in a hypobaric chamber (0.40 atmospheres of air for 24 hours). Myocardial hypertrophy was detected by wet and dry heart weight values when calculated on the basis of total body weight; i.e., ratio heart weight in mg to body weight in 100 g. The behaviour of myocardial hypertrophy was assessed after treatment of intact animals with Puromycin (10 mg/rat i.p.) or Actinomycin-D (100 micrograms/rat i.p.). The experimental results showed the following dry heart weight values (mean +/- SEM): room pressure 60.5 +/- 1.5; hypoxia 69.2 +/- 0.9; Actinomycin-D + hypoxia 63.5 +/- 0.6; Puromycin + hypoxia 62.4 +/- 1.5, (P less than 0.001). From the comparison of data reveals that inhibitors of protein synthesis completely inhibit the myocardial hypertrophy due to hypoxia. Thus it is documented that acute hypobaric hypoxia is able to induce in the rat an actual myocardial hypertrophy condition as expressed of the enhanced protein synthesis.

Animals↗
PubMed1981

The reflex control of arginine-vasopressin release in essential hypertension.

1. The reflex control of arginine-vasopressin release was studied in 12 essential established hypertensive patients and in 12 age-matched normal subjects by comparing the effects of head-up tilt and a variable-pressure neck-chamber. 2. After 45 min 85 degrees head-up tilt, normal subjects showed an increase in plasma arginine-vasopressin and in plasma renin activity, while plasma volume decreased. In hypertensive patients, plasma arginine-vasopressin showed changes after tilt opposite to those of controls, while the changes in plasma renin activity and plasma volume were similar to those observed in the normal group. In both groups the changes in systolic and diastolic blood pressure were not statistically significant. A reduction in carotid sinus transmural pressure obtained by increasing neck-tissue pressure (+50 mmHg) by means of a neck-chamber, evoked different responses in mean blood pressure in the two groups, but failed to induce any significant change in plasma arginine-vasopressin concentration both in the normal and in the hypertensive subjects. 3. These results seem to suggest that carotid sinus baroreceptors, though active in blood pressure control, do not play a direct role in arginine-vasopressin release and, therefore, the opposite response of arginine-vasopressin observed after tilt in the two groups of subjects should be ascribed to more complex mechanisms.

Adolescent↗
PubMed1981

Baroreflex responsiveness in borderline hypertensives: a study with neostigmine.

The baroreflex response to changes in transmural pressure throughout the arterial tree or limited to the carotid sinus was evaluated in ten borderline hypertensives and compared with that observed in ten normal subjects and in ten established hypertensives. Baroreceptor sensitivity was tested by evaluating both heart rate response to phenylephrine-induced increase in arterial pressure and heart rate and blood pressure changes induced by increased neck tissue pressure by means of a neck chamber. The heart rate response to phenylephrine (evaluated by the regression of the R-R interval versus the systolic blood pressure) was depressed both in borderline and established hypertensives as compared with controls. Similarly, the heart rate and the pressor response to increased neck tissue pressure were depressed in both groups of hypertensives. In borderline, but not in established hypertensives, neostigmine administration improved consistently the pressor baroreflex response to increased neck tissue pressure and the heart rate reflex response to both the employed stimuli. These findings indicate that a reduced parasympathetic activity is one of the components involved in the altered baroreflex sensitivity in borderline hypertensives.

Adult↗
PubMed1981

Echocardiographic evaluation of acute administration of oxyfedrine in patients with coronary artery disease.

In order to assess the effects of oxyfedrine in ischaemic heart disease, echocardiographic evaluation of left ventricular function was performed 2,5,10,15 and 20 minutes after the intravenous administration of 12 mg oxyfedrine in 15 patients with coronary artery disease without angiographic abnormalities of left ventricular wall motion. The following parameters were measured: heart rate, mean arterial blood pressure, internal dimension in diastole (LVIDd) and in systole (LVIDs) of the left ventricule and the percentage shortening of the LVID (%LVID). There was a significant increase in %LVID (peak 10 minutes after drug administration; p less than 0.001) indicating improved left ventricular function, associated with slight changes in pre-load (LVIDd) and in heart rate, and no variation in mean blood pressure. No abnormalities of contraction were observed after the administration of oxyfedrine. These results suggest that oxyfedrine exerts a direct positive inotropic effect of the myocardium in patients with significant coronary artery stenoses.

Aged↗
PubMed1981

Non-invasive evaluation by thermistor plethysmography of left ventricular performance during dynamic exercise. Comparison with echocardiography.

The purpose of this study was to evaluate the reliability of two non-invasive techniques (STI and echocardiography) in assessing cardiovascular response during exercise. STI were obtained using a new carotid pulse transducer (thermistor pulse) proved to be reliable in exercise recording. The study population included 12 male rowers (age 15-20 years), who performed supine bicycle exercise; STI and echocardiographic recording of left ventricle were simultaneously obtained at rest and continuously throughout the exercise period. A negative linear correlation (r=-0.782; p less than 0.001) was found between PEP (pre-ejection period) and %LVID (fractional shortening of left ventricle), reliable indexes of cardiac contractility measured by the two techniques. A lower, but significant correlation (r=0.643; p less than 0.001) was present between ETI (left ventricular ejection time corrected by heart rate) and SV (stroke volume) indexes of pump function. The present study shows that STI measured with this new technique, can be employed in evaluating left ventricular function in those patients in whom a good echocardiogram is difficult to record during exercise.

Adolescent↗
PubMed1981

Mechanisms underlying systemic hemodynamic responses to experimental coronary artery occlusion. A preliminary study with hexamethonium.

The hemodynamic changes induced by coronary occlusion were investigated in anesthetized dogs. Coronary occlusion elicited an immediate but transient increase in the systemic blood pressure and in the vascular resistance of the hind limb perfused at constant flow. Thereafter, systemic hypotension and vasodilatation in the perfused region were observed. Vagotomy abolished the initial increase of the systemic and perfusion pressure and reduced significantly the late vasodilator response both systemically and in the perfused hind limb. After the subsequent administration of hexamethonium the vasodilatation in the hind limb was no longer manifest but the fall in blood pressure was unmodified. These results seem to suggest that multiple mechanisms are involved in the hemodynamic response to coronary occlusion.

Animals↗