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Biomedical subjects

P Mazzone

Publications and source records attributed to P Mazzone.

At least 73 records · Page 4Linked to original sources
PubMed1998

Atrial fibrillation in elite athletes.

INTRODUCTION: Atrial fibrillation (AF) is a rare event in people younger than 25 years of age, but is probably more frequent in competitive athletes. We analyzed the presence of AF, paroxysmal or chronic, in a population of young elite athletes, including previous Olympic and World champions, who were studied for arrhythmias that endangered their athletic careers. METHODS AND RESULTS: From 1974 to June 1977, 1,772 athletes identified with arrhythmias (1,464 males and 308 females; mean age 21 years) underwent individualized work-ups. Among these, 146 (122 males and 24 females; mean age 24 years) were young elite athletes. They were studied from 1985 to 1997, with a mean follow-up of 62 months. Of the 146 young elite athletes, 13 (9%) had AF (paroxysmal in 11 and chronic in 2); all were male. The paroxysmal AF occurred during effort (n = 7), after effort (n = 1), or at rest (n = 3) and was reinduced by transesophageal pacing or endocavitary electrophysiologic testing under the same clinical circumstances. AF was the cause of symptoms in 13 (40%) of 22 young elite athletes with long-lasting palpitations. Five young elite athletes had a substrate for AF: Wolff-Parkinson-White syndrome (WPW) in 3, arrhythmogenic right ventricular dysplasia (ARVD) in 1, healed myocarditis in 1, and was considered idiopathic in 8. All elite athletes are alive with a mean follow-up of 62 months and 7 continue in their sports: 3 after radiofrequency catheter ablation (of WPW in 2 and AF with maze-type nonfluoroscopic approach in 1) and 4 after a period of de-training. CONCLUSIONS: AF, occurring in young elite athletes and affecting only males, is one of the most frequent causes of prolonged palpitations and is reproduced easily by transesophageal atrial pacing or electrophysiologic testing. AF may be a cause of disqualification from sports eligibility, but may disappear if the athletic activity is stopped for an adequate period of time, if trigger mechanisms are corrected (i.e., WPW), or if the substrate is modified.

Adult↗
PubMed1997

Effects of increasing doses of apomorphine during stereotaxic neurosurgery in Parkinson's disease: clinical score and internal globus pallidus activity. Short communication.

We analysed the firing activity of internal globus pallidus cells in two Parkinson's disease patients undergoing stereotaxic surgery. Both patients showed an advanced rigid-akinetic syndrome with disabling levodopa induced dyskinesias. Apomorphine, intraoperatively administered at doses (1-2 mg) inducing a short but clear clinical improvement without involuntary movements, reduced the pallidal discharge rate by > 50% in both patients. An higher apomorphine dose (2.5 mg), tested in one hemisphere, blocked the firing activity with a time course independent from the occurrence of dyskinesias. These finding suggest that the reduction of internal pallidus excitability is one of the mechanisms underlying the efficacy of dopaminergic therapy, but also that changes in other basal ganglia stations are likely to be involved in dyskinesias.

Antiparkinson Agents↗
PubMed1997

Inappropriate sinus tachycardia after radiofrequency ablation of para-Hisian accessory pathways.

INTRODUCTION: Inappropriate sinus tachycardia (IST) has been observed following radiofrequency ablation (RFA) of the AV nodal fast pathway. This study was aimed to prospectively analyze the incidence and clinical significance of IST following RFA of para-Hisian accessory pathways (APs). METHODS AND RESULTS: Twenty-eight patients (pts) with para-Hisian APs underwent RFA. An AP was defined as para-Hisian whenever its atrial and ventricular insertions were associated with a His-bundle potential > or = 0.1 mV. RF current was always delivered at the atrial aspect of the tricuspid annulus, to a site where the His-bundle potential was < 0.15 mV. Time- and frequency-domain analysis of heart rate variability was performed in 22 patients, before and after RFA. Abolition of AP conduction was obtained in all pts, and no AV conduction alteration occurred. Six pts (21.4%) presented with IST 45 to 240 minutes after the ablation procedure. In 5 of them, IST disappeared spontaneously within 72 hours, whereas in 1 pt beta-blockers were required for 2 months. The atrial potential amplitude (1.217 +/- 0.264 mV vs 0.882 +/- 0.173 mV, P = 0.009) and A/V potential amplitude ratio (2.633 vs 1.686, P = 0.05) were significantly higher in pts who developed IST than in those who did not. A marked decrease in heart rate variability was observed only in pts who developed IST. CONCLUSION: IST is a relatively frequent complication after RFA of para-Hisian APs: it is generally short-lasting and usually does not require any treatment. IST after catheter ablation is likely to depend upon transient parasympathetic denervation of the sinus node.

Adolescent↗
PubMed1996

Cerebral haemodynamic changes induced by spinal cord stimulation in man.

Spinal cord stimulation (SCS) has been shown to influence cerebral perfusion in both experimental models and humans. With the aim of further verifying such an effect, twelve patients had an epidural (cervical or dorsal) lead inserted percutaneously and underwent regional cerebral blood flow (rCBF) examinations (133-Xenon inhalation method) before and during SCS. Mean blood velocity (MBV) in the middle cerebral artery was also measured in seven cases by means of transcranial Doppler. In the patients with a cervical lead, a symmetrical increase in rCBF was found, mainly in the anterior regions (from +8% to +21%). MBV increased in four cervical lead implants (from +16% to +20%) and in one case with a dorsal lead (+15%). These results suggest that cerebral perfusion may increase in patients undergoing SCS through a cervical lead. Although the mechanism involved in the increase in rCBF remains to be clarified, frontal lobe functional activation by the ascending reticular pathways through the thalamo-cortical projections might be hypothesised.

Adolescent↗
PubMed1996

Structure-activity studies on monoamine oxidase inhibitors by calorimetric and quantum mechanical calculations.

Structure-activity relationship studies were carried out on a new series of hydrazino-thiosemicarbazide derivatives, which inhibit monoamino oxidase (MAO). Fifty-five compounds were synthesized and tested "in vitro" for their inhibitory effects on rat liver mitochondrial MAO. The most efficient MAO inhibitors were the benzylidene derivatives (sequence: see text] where R is the piperonyl radical and ethyl or isopropyl substituents are in R1 position. Correlation of MAO activity with hydrophobic, electronic and steric properties of tested compounds, evaluated by means of Quantum Mechanical calculations and calorimetric analysis (DSC) suggest that electronic and steric parameters give a better fit than hydrophobicity with the biological activity.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1996

[Radiofrequency catheter ablation of atrial tachycardia: technique, results and follow-up].

BACKGROUND: Recently radiofrequency (RF) catheter ablation (CA) of atrial tachycardia (AT) showed to be highly effective with a low incidence of compliance. Aim of our study was to report the results and follow-up of RFCA of drug-refractory AT in 59 consecutive patients (pts). METHODS: Two mapping techniques were used to localize the ablation site of AT: the earliest atrial activation and the pace-mapping. Traumatic interruption of AT was used to verify the ablation site identified by the previous procedures. Moreover we evaluated the sensitivity, specificity and the positive predictive value of the three mapping techniques. RESULTS: AT was successfully treated in 55/59 (93.2%) pts with a mean of 4.0 +/- 3.8 (range 1-16) RF pulses for patient. The mean procedure time was 185.2 +/- 48.5 min with a mean rx-time of 41.5 +/- 21.3 min. An interval between the onset of the intracavitary atrial deflection and the onset of the P-wave, during atrial tachycardia, (AP interval) > or = 30 ms and pace-mapping concordant sequence were highly sensitive (90.9% and 89.1%) but less specific (49.2% and 33.9%) in identifying the site of ablation. By using atrial tachycardia traumatic interruption combined with the AP interval > 30 ms or the pace-mapping concordant sequence we obtained a specificity of 78.7% and 77.0% respectively and a positive predictive value of 48.0% and 46.8% respectively. Four recurrences (7.3%) were observed during a mean follow-up of 23.4 +/- 13.3 months. In the 22 (37.3%) pts with dilated cardiomyopathy, chest Xr and echocardiography showed a significant decrease of cardiothoracic index (0.56 +/- 0.08 pre ablation, 0.43 +/- 0.07 post ablation, p < 0.001) and end-diastolic diameter (64 +/- 8 mm pre ablation, 52 +/- 8 mm post ablation, p < 0.001) and a significant improvement of left ventricular ejection fraction (37 +/- 9% pre ablation, 48 +/- 11% post ablation, p < 0.05). CONCLUSION: The RFCA of AT was effective and safe. Moreover we observed a hemodynamic improvement in patients with reduced ejection fraction and increased cardiac volumes. An AP interval > or = 30 ms and the pace-mapping concordant sequence were reliable features to predict the outcome of the ablation procedure. Traumatic ablation of atrial tachycardia improved the specificity and the positive predictive value of these two mapping techniques and was able to predict the response to radiofrequency with a high specificity.

Catheter Ablation↗
PubMed1996

Multi-layer neural network analysis of cerebrospinal fluid pressure patterns in idiopathic normal-pressure hydrocephalus.

The cerebrospinal fluid (CSF) pressure patterns have been reported as one of the most relevant indexes for the diagnosis and treatment of idiopathic normal-pressure hydrocephalus (INPH). Forty consecutive patients coming from our observations with the classic Hakim's triad underwent continuous CSF pressure monitoring via lumbar puncture for at least 12 hours. Twenty-eight patients were diagnosed as having INPH and underwent CSF shunt. A multi-layer neural network (perceptron) was employed to study the pressure patterns in order to try an alternative classification to the "expert" neurosurgeon one. Differences between expert and neural network classifications were indeed observed. Such differences may depend on the small group studied or on the inadequacy of CFS pressure patterns in correctly individuating those INPH patients who benefit from shunt surgery. The authors think that neural network processing of INPH could add relevant information to select the "responder" patients to surgery: in fact neural networks represent a powerful methodology for aiding the expert to select the proper choice on the basis of "what learnt" by the networks themselves.

Cerebrospinal Fluid↗
PubMed1995

Inhibition of rat liver mitochondrial monoamine oxidase by hydrazine-thiazole derivatives: structure-activity relationships.

The purpose of this research is to study the relationship between chemical structure and inhibitory activity of some hydrazine-thiazole derivatives on rat liver mitochondria monoamine oxidase (MAO). Forty-five compounds belonging to three series of hydrazine-thiazole derivatives, with either alkylic or arylic substituents in the thiazole ring, were tested. The highest inhibitory activity was observed with piperonyl derivatives 25 and 40, which contain a 4-methyl group in the thiazole nucleus. The structure-activity relationship of MAO inhibitors was established in relation to hydrophobic, electronic and steric hindrance parameters. A mechanism of enzyme inhibition was proposed based on the calculation of HOMO energies.

Animals↗
PubMed1995

Assessment of regional cerebral blood flow during spinal cord stimulation in humans.

Increased cerebral perfusion has been reported in both animal models and humans undergoing spinal cord stimulation (SCS). However, this was an inconsistent finding and variables able to influence regional cerebral blood flow (rCBF) following SCS are poorly investigated. We report our experience on rCBF measurements by the xenon-133 inhalation technique in 20 patients receiving acute and chronic SCS for different pathologies in basal conditions. Neither acute nor chronic SCS induced significant rCBF changes in the group of patients as a whole. However females, non-atherosclerotic patients and patients with a cervical SCS lead, showed a trend (borderline statistical significance) toward a redistribution of rCBF with increased values in frontoprerolandic and decreased values in postrolandic regions. Although SCS appears to influence intracerebral distribution more than absolute changes in blood flow, the mechanisms underlying such a phenomenon remain unknown. Functional activation of frontal lobes by the ascending reticular pathways through the thalamofrontal projections could be one possible hypothesis which has to be confirmed by further studies.

Administration, Inhalation↗
PubMed1994

Correlation between monoamino oxidase inhibitor activity of some thiazol-2-ylhydrazines and their interaction with dipalmitoylphosphatidylcholine liposomes.

A calorimetric investigation has been carried out on the influence exerted by some 1-(alkoxybenzoyl)-2-(4-substituted thiazolyl-2-yl)hydrazines, possessing monoamine oxidase inhibitory (MAOI) activity, on the thermotropic behavior of model membranes constituted by dipalmitoylphosphatidylcholine (DPPC) vesicles. Attention was paid to evaluate how structural variations of drugs may influence drug-lipid interaction. The examined drugs were found to modify the gel to liquid-crystal phase transition of DPPC liposomes, by causing a shift of the transition temperature (Tm) toward lower values and a negligible variation in the enthalpy changes (delta H). The different effects on DPPC thermotropic behavior of these MAOI drugs could be considered in terms of different substituents on the molecule's backbone. The calorimetric results were related to drug's MAO inhibitory activity measured by fluorescence techniques and the apparent distribution coefficient of the compounds in water/n-octanol. A hypothesis on a correlation between a drug's structure, inhibitory activity, and membrane interaction has been suggested.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1994

Monitoring of the discrimination threshold for interocclusal thicknesses in rehabilitated edentulous patients.

Thirty-seven white Caucasian subjects with unsatisfactory dentures were tested for interocclusal thickness discrimination threshold. New dentures were prepared and the test was repeated on days 1, 4 and 90 (from delivery). Eight patients whose situation was still unsatisfactory were given osseointegrated implant anchored dentures and the test repeated at the same intervals. Results were analysed statistically. Improved denture fit was found to increase interocclusal sensitivity. Decreased sensitivity during follow-up might indicate the need to check denture fit.

Aged↗
PubMed1994

Cerebral blood flow and somatosensory evoked response changes induced by spinal cord stimulation: preliminary follow-up observations.

A group of 6 patients undergoing cervical spinal cord stimulation (SCS) because of different pathologies was studied. Multipolar leads (QUAD-Medtronic) were inserted percutaneously; following an SCS test period, leads were connected to a multiprogrammable, fully implantable generator (ITREL II). Neither surgical nor other side effects were found. Regional cerebral blood flow (rCBF) (xenon-133 inhalation) was determined in the basal condition and after 30 min of SCS. Somatosensory-evoked potential (SSERs) from the legs were recorded in basal conditions and after 45 min of SCS. In 2 patients SSERs could not be evaluated due to electrical noise from SCS. CBF increased mainly in anterior regions in 4/6 patients (P300 improved in 1 of them and in another case), and was unchanged in 2 patients. rCBF was retested after a mean of 9.5 months of continuous SCS with the same parameters. rCBF returned to basal values in the 4 patients showing an early flow increase; in contrast, rCBF increased in the other 2 cases without early flow changes. These preliminary data seem to support the view of an acute effect of SCS on rCBF as well as on SSER, at least in some patients. Differences in long-term rCBF modifications might depend on either the underlying pathology or on the different neuronal system involved by SCS.

Adolescent↗
PubMed1994

MAOI activity of thiosemicarbazides and related 2-thiazolylhydrazines.

The preparation is described of hydrazides I, thiosemicarbazides II, III, IV and hydrazinothiazoles VIII, which can be considered as "precursors" or "open models" for the synthesized benzoyl-, benzilidene- and benzyl-hydrazinothiazoles V, VI and VII, analogous to 4-methyl and 4-phenyl substituted derivatives A, B and C, described and tested for their MAOI activity in a previous paper. Biochemical assay on the new prepared compounds allowed us to better clarify the structure-activity relationship also of compounds A, B and C of the precedent note. Moreover, on a group of derivatives, which showed a higher activity, a further test was performed to observe the possible correlation between MAOI activity and both their lipophilicity and ability in interacting with liposome bilayers, taken as a model of cell membrane.

Animals↗
PubMed1993

Synthesis and local anesthetic activity of alkylaminoacyl derivatives of 2-amino-1,3,4-thiadiazole.

We prepared some series of 2-(alkylaminoacyl) derivatives of 2-amino-1,3,4-thiadiazoles. Most terms were subjected to a biological screening showing a local anesthetic activity both in infiltration and trunkular tests. For some of the assayed derivatives, the activity was comparable to that of lidocaine, taken as the reference molecule. From the obtained results an acceptable relationship between some structural features and activity was drawn.

Anesthetics, Local↗
PubMed1992

MAOI activity of some novel series of substituted thiazol-2-yl-hydrazines.

Three series of 2-thiazolylhydrazines were synthetized and evaluated for their MAO inhibitory (MAOI) activity, both by in vivo tests, to assay their influence on several MAOI activity-related parameters (the variation on blood pressure induced by tyramine and clonidine and L-amfetamine-induced hypermotility) and in vitro tests, to assay their effect on rat brain mitochondria by a kinuramine fluorimetric assay. In vivo, all the tested compounds significatively influenced the evaluative parameters used. As regards in vitro test, all compounds displayed MAOI activity at a concentration of 1.10(-4) mol.l-1, which was significant in several cases. In the discussion of the results, the influence of the structure on the biological activity of the prepared compounds was delineated.

Amphetamine↗
PubMed1988

Treatment of severe renovascular hypertension by percutaneous transluminal renal angioplasty in patients with solitary functioning kidney. Effects on blood pressure and renal function.

In this study the effects of percutaneous transluminal renal angioplasty on blood pressure and renal function were studied in 9 hypertensive patients with stenosis of the main artery of a solitary functioning kidney. The outcome of the percutaneous dilatation of the renal artery stenosis, and the effects on blood pressure and renal function were evaluated for a mean period of 16.4 +/- 2.13 (SE) months (ranging from 3 to 65 months). A successful dilatation of the renal artery stenosis was shown in all the patients by the aortography performed 1 h after the procedure. At the discharge (7.8 +/- 0.9 days after dilatation), blood pressure was 'cured' in 2 patients and 'improved' in the remaining patients; renal function was improved in all patients who had reduced renal function. At the last follow-up, no restenosis was found in patients who repeated the follow-up angiography; blood pressure was 'cured' in 3 patients and 'improved' in 6 patients, and renal function appeared steadly improved. In contrast with other reports, our results demonstrate that percutaneous renal angioplasty is a safe and effective procedure and should be attempted before considering surgical intervention in patients with artery stenosis of a solitary functioning kidney.

Adult↗