Electron microscopy study on the cardiac muscle of rats after adriamycin administration

A delayed cardiomyopathy, similar to that observed in cancer patients treated with the anthracycline antibiotic, adriamycin, was produced in the rat. Thirty animals were employed, divided into control and experimental groups which include the recovery period. A single dose of 6 mg/kg and cumulative dose of 15 mg/kg [six injections of 2.5 mg/ kg over two weeks] were administered intraperitoneally to the rats. In both doses, this syndrome was characterized by congestion of the myocardial vessels and focal to disseminated myofiber degeneration and necrosis. Alterations in myocardial cells were characterized by degeneration of mitochondria accompanied by myofibrillar breakdown and myolysis. The spectrum of myofiber alterations observed suggests two possible mechanisms which might explain the pathogenesis of the lesions observed in myocardial cells of the treated animals. The interference of anthracycline antibiotic with DNA-dependent RNA synthesis and the presence of nucleolar alterations suggest that the mycoardial lesions may be related to abnormal subcellular necrobiosis and a subsequent failure of the cell to renew mitochondrial and myofibrillar proteins. The similarity of these lesions to those produced by a wide variety of myocardial and general cellular toxins also suggests that more direct injury to sarcoplasmic components may be important in the pathogenesis of adriamycin cardiomyopathy

Catecholamine induced myocardial necrosis an experimental study with potential clinical implications [part 1]

Myocardial necrosis does not imply only coronary artery disease. It might be due to accelerated O2 consumption due to heightened sympathetic activity with consequent depletion of ATP and creatine phosphate. This study induced myocardial necrosis in rats through excessive beta-adrenergic stimulation using isoprenaline [Iso] infusion, aiming at establishing the validity of an experimental model. 54 adult albino rats with an average weight 115 g were studied. The animals were divided into a control group [10 rats] and Isop. treated group [44 rats]. In conclusion, isoprenaline could induce myocardial necrosis in rats in a dose dependent fashion without ligating the coronary arteries. An attempt has been made to draw analogy between necrosis lesions that IV catecholamines could induce in experimental animals and possible similar lesions that excessive and ogenous catecholamines can produce in human beings

Endomyocardial biopsy in schistosomiasis: an immunological and histopathological study

To study left ventricular affection in schistosomiasis, left ventricular endomyocardial biopsies from 24 patients with schistosomal hepatic fibrosis - half of them had schistosomal cor pulmonale - were examined under light microscopy for histopathologic alteration and under fluorescent microscopy for the presence of immunofluorescence for Schistosoma mansoni egg antigen, IgG and complement C3. Serologic tests for the quantitation of IgG, IgM and complement C3 and ELISA test for antischistosoma mansoni antibodies were done. The endomyocardial biopsies revealed increased endocardial thickness and endocardial smooth muscle cell content, myocardial fiber hypertrophy, variable degrees of interstitial fibrosis and signs of myocardial fiber damage. Statistical analysis confirmed that these pathologic alterations correlated well with both cardiac immunofluorescence and serologic data. The level of pulmonary artery pressure had no relation to any of these abnormalities in patients with schistosomal cor pulmonale

Experimental dilating cardiomyopathy and verapamil therapy in the mice

The effects of verapamil, a calcium channel blocker were examined on the norepinephrine and tyramine induced changes in mice myocardium. Tyramine but not norepinephrine [5 mg/kg/day, s.c. for 5 days] caused significant increase in cardiac mass reflected by increase ratios of heart wet and dry weights to body weight. The histopathological changes seen by light microscopy include cell necrosis and fibrosis with hypertrophied nuclei. Simultaneous treatment of the animals with verapamil [1 mg/kg/day, s.c. for 5 days] attenuated the above mentioned changes that were induced by catecholamines. Based on the data obtained in this study, it is proposed that catecholamines induced changes in the myocardium may involve facilitation of calcium entry which induce cell necrosis and lead to the development of dilated cardiomyopathy and verapamil is capable to attenuate these changes

Efecto de la reinfeccion sobre la evalucion de ratas infectadas con Trypanosoma cruzi / Effect of reinfection on the evolution of rats infected with Trypanosoma cruzi

El objetivo de este trabajo fue comprobar si una de las variables medio-ambientales, la reinfeccion, puede modificar el comportamiento observado en un modelo de rata a nivel de parasitemia, anticuerpos sericos, manifestaciones electrocardiograficas y/o lesion miocardica. Los grupos experimentales fueron: GI: ratas infectadas al destete com 1 x "10 POT 6" T. cruzi; GR: igual a GI mas reinfecciones cada 30 dias hasta los 150 dias post-infeccion inicial (p.i.i.); "GI IND 1". Los xenodiagnosticos fueron negativos en los tres grupos. Los anticuerpos sericos no se modificaron significativamente en GR respecto de GI, salvo en los anticuerpos 7S, pues los del GR presentaron titulos superiores en algunos de los dias estudiados. Los ECG basales no mostraron cambios distintivos en las ratas infectadas. La pruieba de ajmalina mostro una disminucion de la FC independiente del tratamiento; el PR, QaT y QRS se prolongaron significativamente en todos los grupos respecto del basal (p < 0.05), salvo el QaT en el GT; ademas el cambio de PR y QaT fue mayor en los infectados (p < 0.05). En los grupos infectados hubo tambien una amplia variacion en la orientacion del eje electrico respecto del valor basal, acompanado de cambios morfologicos mas manifiestos emGR. La proporcion de lesion cardiaca detectada histologicamente en los grupos