Scanning electron microscopy (SEM) with secondary electron emissions is useful for the study of cardiomyocyte architecture, however, the information is limited from the cell surface. Whereas backscattered electron (BSE) emission can give a high-resolution image of the specimen's intracellular structure after heavy metal staining. In this study, we applied BSE imaging analysis to the study of the arrangement of cardiomyocytes in the myocardium. The tissue specimens from a normal fresh monkey heart, normal human heart obtained at autopsy, and surgically resected tissue from a patient with old myocardial infarction in the left ventricular aneurysmectomy were used. The tissue specimens were fixed in neutral formalin, treated with NaOH and then stained with Gomori's silver methenamine reagent followed by tannic acid and osmium tetroxide. After dehydration and drying, the specimens were coated with carbon and examined by SEM with a BSE detector. In the tissue preparations, the A bands of sarcomeres were selectively stained with silver so that the arrangements of subsarcolemmal myofibrils and the intercalated discs were clearly seen in the BSE images. In the left ventricular aneurysmal walls of old myocardial infarction, atrophied cardiomyocytes with disarray of subsarcolemmal myofibrils were observed. The results strongly suggest that BSE images are further applicable to the study of the architecture of cardiac myocytes and their branches, and the arrangement of intracellular myofibrils in various diseased myocardium.

Animals↗

PubMedDate not supplied

Myocardial inflammatory cell infiltrates in cases of dilated cardiomyopathy: light microscopic, immunohistochemical, and virological analyses of myocardium specimens obtained by partial left ventriculectomy.

OBJECTIVE: Partial left ventriculectomy was introduced for the treatment of refractory dilated cardiomyopathy (DCM). To determine the presence and degree of inflammatory cell infiltrates in DCM and the correlation between the underlying myocardial injury and early clinical outcomes after the operation, we performed histopathological, immunohistochemical, and virological studies of the resected myocardium. METHODS: Posterolateral walls of the left ventricle from 13 idiopathic DCM patients (9 males and 4 females; mean age = 53+/-14 years) were examined. Qualitative and quantitative analyses of the interstitial fibrosis and of the infiltrating inflammatory cells were conducted. For the immunohistochemistry, leukocyte surface markers and antibodies to adhesion molecules and cytokines were used. The histopathological findings were compared with the clinical results, including outcome within 1 year, and pre- and postoperative hemodynamic data. Genomic analysis of the myocardium with polymerase chain reaction was performed for enterovirus, mumps, influenza A, cytomegalovirus, and hepatitis C virus. RESULTS: (1) The three patients who died of cardiac insufficiency after surgery had a higher count of infiltrating inflammatory cells than the eight survivors (32.1+/-10.4 vs 16.3+/-11.9 cells/mm2, p = 0.07). The severity of interstitial fibrosis (percent fibrosis) did not differ significantly between these two groups (28.3+/-15.0 vs 24.0+/-11.7%). (2) In patients who died of myocardial dysfunction, focal accumulations of lymphocytes were common, in which cytotoxic/suppressor T cells and helper/inducer T cells were observed. (3) Enterovirus genome was detected in the myocardium of two patients, both of them died after surgery. CONCLUSIONS: Inflammatory cell infiltrates or active myocarditis appear in some cases to play an important role in the etiology and pathophysiology of clinically diagnosed DCM. There is a possibility that those patients with a more severe or ongoing inflammatory process might have poor outcomes after partial left ventriculectomy.

Adult↗

PubMedDate not supplied

Enterovirus RNA replication in cases of dilated cardiomyopathy: light microscopic in situ hybridization and virological analyses of myocardial specimens obtained at partial left ventriculectomy.

OBJECTIVE: Recently, attention has been focused on enteroviral infection of the heart in the genesis of dilated cardiomyopathy (DCM). To determine the location of enteroviral RNA in the myocardium, we performed light microscopic in situ hybridization (ISH) and virological analyses of myocardial specimens obtained at partial left ventriculectomy (PLV). METHODS: Posterolateral walls of the left ventricle from 26 DCM patients were examined. Myocardial specimens were tested for the presence of enteroviral genomes by polymerase chain reaction (PCR). We selected two age-matched groups (10 patients each) in which enteroviruses were either present (EV-plus group) or not (EV-minus group). For both groups, we examined in situ localization of enteroviral RNA in the myocardium by ISH. RESULTS: In PCR studies, both sense and antisense enteroviral RNA were detected in the myocardium of seven patients in the EV-plus group. The presence of this RNA indicates active viral replication in the myocardium. Five of seven patients who exhibited both sense and antisense enteroviral RNA died early after surgery. On ISH, three patients had evidence of active replication of enteroviral genomes. Viral genomes were present in myocardial lesions, especially in endocardial sites. Viral signals were found in degenerating myocardial cells, interstitial inflammatory cells, and endothelial cells of small vessels. These positive signals were not detected in the myocardium of the EV-negative group. CONCLUSIONS: We detected both sense and antisense enteroviral RNA in various myocardial lesions. This suggests that active enteroviral replication plays a role in the development of myocardial lesions in DCM patients. Active viral replication appears to be a prognostic factor for DCM after PLV. Further study of active viral replication in myocardial lesions will provide information useful for evaluating different therapeutic strategies for DCM.

Adolescent↗

PubMedDate not supplied

Three dimensional configuration of mitochondria in left ventricular myocyte in mitochondrial cardiomyopathy: scanning electron microscopy by the osmium-DMSO-osmium method.

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Cardiomyopathies↗