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Biomedical subjects

T Guarnieri

Publications and source records attributed to T Guarnieri.

11 recordsLinked to original sources
PubMed1992

Anti-Ro/SS-A antibodies in the pathophysiology of congenital heart block in neonatal lupus syndrome, an experimental model. In vitro electrophysiologic and immunocytochemical studies.

OBJECTIVE: To determine whether anti-Ro/SS-A antibodies selectively bind to neonatal cardiac cells and alter membrane repolarization. METHODS: An in vitro electrophysiologic and immunocytochemical experimental model contrasting neonatal and rabbit cardiac tissue was employed. RESULTS: Sera and IgG-enriched fractions from anti-Ro/SS-A antibody-positive mothers of infants with neonatal lupus erythematosus and congenital heart block bind to neonatal, rather than adult, rabbit cardiac tissue and alter the transmembrane action potential (i.e., inhibit repolarization). The additional presence of anti-La/SS-B antibodies was not additive or synergistic for these immunocytochemical and electrophysiologic features. Sera containing other antibody specificities (i.e., anti-native DNA, cardiolipin, Sm, and nuclear RNP) failed to stain the neonatal cardiac tissue or produced alterations in membrane repolarization. CONCLUSION: Anti-Ro/SS-A antibodies may play a pathophysiologic role in the development of congenital heart block in neonatal lupus.

Action Potentials↗
PubMed1991

Testicular dysfunction with amiodarone use.

Amiodarone, an antiarrhythmic drug approved for use in patients who survive cardiac arrest, has been associated with infiltration of or inflammatory changes in various tissues. To date thyroid dysfunction has been the only endocrine disturbance noted. In an initial group of seven amiodarone-treated men undergoing evaluation for sexual dysfunction, an elevation in serum gonadotropin concentration was detected, suggesting testicular dysfunction. Because of this finding, gonadal function was prospectively evaluated in 44 men (18 who had been treated with amiodarone for greater than 1 year and 26 survivors of cardiac arrest who had been treated with antiarrhythmic drugs other than amiodarone). Amiodarone-treated men had higher serum follicle-stimulating hormone (41.8 +/- 22.8 vs. 14.4 +/- 10.4 mIU/ml, p less than 0.001) and luteinizing hormone (34.8 +/- 26.4 vs. 10.1 +/- 5.2 mIU/ml, p less than 0.001) concentrations compared with control subjects. Although serum total and free testosterone levels were comparable between the two patient groups, these levels were inversely correlated (r = -0.53, p less than 0.05; r = -0.62, p less than 0.01, respectively) with cumulative amiodarone dose. Hyperresponsiveness to the administration of gonadotropin-releasing hormone was noted in the 10 amiodarone-treated men evaluated by this diagnostic test. Sexual dysfunction was common in both groups (70% of control subjects and 82% of amiodarone-treated subjects), although atrophic testes were more commonly observed in amiodarone-treated men (p less than 0.05). Because of the elevated serum gonadotropin level, it is concluded that testicular dysfunction may result from prolonged amiodarone treatment.

Adult↗
PubMed1991

Substance P in the habenulo-interpeduncular system of the goldfish.

The distribution of substance P (SP)-like immunoreactivity has been studied in the habenulo-interpeduncular system of the goldfish in normal conditions and after habenular ablation. In normal conditions intense SP-like immunoreactivity was observed in the neuropilar structure of the interpeduncular nucleus (IPN). No SP-like immunoreactive cell bodies were observed in the habenular nuclei (HBN), but some SP-like immunoreactive fibres were localized in the central core of the nucleus. Following surgical habenular ablation SP-like immunoreactivity was reduced in the IPN. The image analysis performed on the IPN showed clear-cut transmittance changes in the area examined. The results suggest that SP is involved in connecting HBN and IPN in goldfish, and are consistent with the data of mammals and other vertebrates.

Animals↗
PubMed1991

Long-term follow-up of patients with nonischemic dilated cardiomyopathy and ventricular tachyarrhythmias treated with implantable cardioverter defibrillators.

We analyzed our 10-year cumulative experience of 40 consecutive patients with idiopathic dilated cardiomyopathy and associated ventricular tachyarrhythmias, treated with implantable cardioverter defibrillators. Dilated cardiomyopathy was defined as left ventricular ejection fraction (EF) less than or equal to 50% with no defineable etiology. Patient characteristics included: 24 male, mean age 52 years, mean EF = 33%, New York Heart Association Class I-III, presenting syndrome--cardiac arrest (n = 28), syncope/near syncope (n = 12). At 2.5 years mean follow-up, there were 16 deaths: one operative, three sudden, two incessant ventricular tachycardia/ventricular fibrillation (VT/VF), six heart failure, and four noncardiac. The actuarial mortality at 1 and 4 years was 0% and 14% for sudden death, 11% and 34% for cardiac death. The projected mortality was 52% and 78% for same time intervals (P less than 0.01). No useful baseline variable predicted who would or would not receive an ICD shock in follow-up. ICD therapy appears effective in reducing sudden death mortality in this high risk population.

Cardiomyopathy, Dilated↗
PubMed1991

The interaction of antiarrhythmic drugs and the energy for cardioversion of chronic atrial fibrillation.

Antiarrhythmic drugs may alter the energy for cardioversion of ventricular arrhythmias. This study compares the energy necessary for cardioverting chronic atrial fibrillation in 57 patients taking type Ia, Ic, or type III antiarrhythmic drugs. Patients taking Ia (n = 22) or III (n = 14) drugs had a median energy for cardioversion of 100 joules, while the patients taking Ic (n = 17) drugs had a median energy of 200 joules (P = 0.03). There were no differences in the frequency of unsuccessful cardioversion. There were no serious adverse events in any of the three groups, although three patients in the Ic group had greater than 3 second pauses after the shock. The data suggest that the use of Ic antiarrhythmic drugs results in a higher energy for cardioversion of atrial fibrillation. However with higher energies, conversion is as successful as for type Ia and type III.

Amiodarone↗
PubMed1991

Predictors of first discharge and subsequent survival in patients with automatic implantable cardioverter-defibrillators.

BACKGROUND: Two hundred eighteen patients were evaluated in a two-phase approach (time to first appropriate discharge, survival after discharge) to identify factors that may be related to maximal benefit derived from use of an automatic implantable cardioverter-defibrillator (AICD). METHODS AND RESULTS: One hundred ninety-seven patients survived implantation of AICD, with or without concomitant cardiac surgery. One hundred five patients had an AICD discharge associated with syncope, presyncope, documented sustained ventricular tachycardia or fibrillation, or sleep at 9.1 +/- 11.1 months after implantation. Patients survived 23.8 +/- 18.0 months after AICD discharge. Left ventricular dysfunction (p = 0.008 for ejection fraction less than 25%) was associated with earlier AICD discharge and shortened survival after AICD discharge (p = 0.008 for ejection fraction less than 25%; p = 0.01 for New York Heart Association functional class III and IV). beta-Blocker administration (p = 0.006) and coronary bypass surgery (p = 0.06) were associated with later AICD discharge. Coronary bypass surgery (p = 0.035) but not beta-blockers was associated with more prolonged survival after AICD discharge. CONCLUSIONS: These data suggest that a relatively easy algorithm can be applied to predict which patient will benefit most from AICD implantation.

Electric Countershock↗
PubMed1991

Cardiac disturbances during the administration of taxol.

The clinical development of taxol, a new antimicrotubule agent with a unique mechanism of cytotoxic action, has proceeded slowly due to serious hypersensitivity reactions (HSRs) and shortages in its supply. Nevertheless, large-scale phase II trials have been initiated as taxol has recently demonstrated impressive activity in advanced and cisplatin-refractory ovarian carcinoma. Furthermore, the incidence of HSRs has been reduced substantially with premedications and modifications in the administration schedule. However, various manifestations of potential cardiotoxicity have been observed in several patients who participated in four phase I and II studies of taxol. Asymptomatic bradycardia has occurred in a high proportion of patients, including 29% of ovarian cancer patients who were treated with maximally tolerated doses of taxol in a phase II study. More profound cardiac disturbances, including a range of atrioventricular conduction blocks, left bundle branch block, ventricular tachycardia (VT), and manifestations of cardiac ischemia, have been observed in seven of 140 patients (5%) who received taxol. Descriptions of these events are presented in this report to alert investigators to the potential for these adverse effects. Although these disturbances did not result in serious sequelae in most patients, investigators should continue to maintain a high degree of caution until precise risk factors, frequency, and clinical significance of these adverse cardiac effects are determined.

Aged↗
PubMed1990

Effect of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in goldfish brain.

The neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), which selectively damages dopaminergic neurons in mammals, caused a marked depletion of tyrosine hydroxylase (TH) immunoreactivity in the goldfish brain. The concomitant ultrastructural observations showed the neurotoxic effect of MPTP on telencephalic, diencephalic and medullar neurons. The affected neurons revealed darkening of the cytoplasm and swelling of the mitochondria and the endoplasmic reticulum. Concomitant significant decreases in dopamine (DA) and noradrenaline (NA) levels were determined in the brain areas where morphological observations were performed. The loss of catecholamine levels was completely prevented by the treatment with the monoamine oxidase (MAO) inhibitor pargyline to prevent MPTP oxidation. The results indicate that in goldfish brain, acute MPTP administration causes selective catecholamine depletion, without altering the serotoninergic system.

Animals↗
PubMed1978

Effect of tris(hydroxymethyl)aminomethane on ischemic myocardium.

Intracellular acidosis may depress myocardial function and metabolism during ischemia. In the present study, the function and metabolism of a globally ischemic, isovolumic cat left ventricle preparation, perfused with oxygenated Krebs-Ringer biocarbonate solution, was examined. Addition of tris(hydroxymethyl)-aminomethane (Tris) (15 mM) to the perfusate at physiologic pH and PCO2 increased performance during ischemia to a greater extent and for a longer period than low PCO2 )15 mmHg), alkalotic (pH, 7.8) perfusate and a control sucrose perfusate. Under nonischemic conditions the inotropic effect of Tris was only briefly greater than sucrose perfusate. The inotropic effect of Tris during ischemia did not appear to depend on changes in coronary flow, oxygen consumption, sodium concentration, perfusate osmolality, or catecholamine release. During ischemia, lactate production was unchanged with Tris, but increased with low PCO2-alkalosis. Tissue levels of ATP and creatine phosphate for control ischemic hearts did not differ from Tris-perfused or low PCO2-alkalosis hearts. Thus, Tris appears to exert an inotropic effect that is more prominent in ischemic than nonischemic myocardium. The results are consistent with the possibility that Tris acts as an intracellular buffer to increase the efficiency of energy production and/or utilization during ischemia.

Adenosine Triphosphate↗