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Biomedical subjects

Y Kitaura

Publications and source records attributed to Y Kitaura.

At least 55 records · Page 3Linked to original sources
PubMed1990

Experimental influenza A virus myocarditis in mice. Light and electron microscopic, virologic, and hemodynamic study.

To elucidate the heart involvement associated with influenza virus infection, the authors studied the hearts of influenza A/PR/8/34 virus-inoculated ICR mice by light and electron microscopy, cardiac catheterization, virus assay, and indirect immunofluorescence. Light microscopy showed small necrotic foci with inflammatory cell infiltration spreading in the myocardium on days 3 to 7 and evidence of healing by day 9 after inoculation. Electron microscopy demonstrated that necrotic cell debris was phagocytosed by macrophages, and that degenerating cardiocytes, macrophages, and lymphocytes were often in close contact, suggesting immunologic interactions, and that platelet thrombi were present in some capillaries on days 3 to 5. Both systolic and diastolic functions of the left ventricle (LV) were impaired on days 3 to 9 and recovered almost to normal by day 14. The virus could be isolated from the heart on days 3 to 7. Immunofluorescent preparations showed virus antigens in the vascular walls and cardiocytes until day 7. These results suggest that the acute cardiac injury was related to cytotoxic immunologic interactions, virus-induced cytolysis and, at least in part, to ischemia due to intracapillary thrombosis. Compared with coxsackie B3 myocarditis in mice, the influenza myocarditis was mild in degree and short in duration, but the influenza infection is a most common and repetitive disease in humans. The clinical implications of this animal model with myocarditis are discussed.

Animals↗
PubMed1989

Cell-mediated immune cardiocyte injury in viral myocarditis of mice and patients.

The cellular immune mechanism of cardiocyte injury in viral myocarditis was investigated by observing and analyzing the interactions among cardiocytes, T cells, B cells, natural killer (NK) cells and macrophages in situ in the myocardium of our murine model (C3H/He mice) and of human patients. In murine coxsackie B3 virus myocarditis, lymphocyte subsets were identified by light and electron microscopic immunohistochemical techniques with antibodies against specific antigens of pan T (Thy 1.2), helper/inducer T (Th/i) (Lyt 1+), cytotoxic/suppressor T (Tc/s) (Lyt 2+), B (Ig+) and asialo GM1+ cells in the myocardium. In the acute phase of myocarditis, asialo GM1+ (mostly NK) cells predominated over pan T cells and peaked on day 9. Pan T cells then reached a peak on day 14. The T4/T8 (Lyt 1+/Lyt 2+) ratio was 1.3 +/- 0.5 on day 5 and reached a peak of 9.1 +/- 3.6 with an increase of Lyt 1+ cells on day 14. Thereafter, NK cells and T cells gradually decreased and could still be seen in fibrotic foci even 3 and 12 months later. B cells were so scarce that no quantitative evaluation could be made. Electron microscopy revealed that macrophages were in close contact with Th/i cells, target cardiocytes and less commonly, B cells; Tc/s and NK cells also occasionally conjugated with apparently viable or degenerated cardiocytes. Some lymphocytes were located in widened intercellular spaces of dissociated intercalated discs, and in intracytoplasmic widened confines of some cardiocytes (emperipolesis). These results suggest that in the acute phase of myocarditis, NK cells initiate the reaction, and then sensitized cytotoxic T cells and activated macrophages aggravate cell-mediated injury by their close contacts with target cardiocytes; close contacts among macrophages; Th/i cells and a few B cells, and the increased T4/T8 ratio may facilitate regulation of the complex immune network; in the chronic phase, residual but active NK and cytotoxic T cells may sustain cytotoxicity. In the endomyocardial biopsies obtained from 8 patients with viral or idiopathic myocarditis from 3 to 48 days after the clinical onset, conventional electron microscopy revealed actual contacts among cardiocytes, macrophages and lymphocytes. As in our murine model, some lymphocytes had emperipolesed in cardiocytes or were located in widened spaces of dissociated intercalated discs. In 4 of these 8 patients infiltration of Leu 2a+ Tc/s, Leu 3+ Th/i and Leu 7+ cells was identified immunohistochemically, and T4/T8 ratios varied widely from 0.1 to 3.8 in the endomyocardial biopsides.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1987

Functional and histopathologic correlation in patients with dilated cardiomyopathy: an integrated evaluation by multivariate analysis.

To correlate left ventricular function and histologic features in patients with dilated cardiomyopathy, precise indexes of hemodynamics and semiquantitative histologic data were combined for multivariate analysis. Right endomyocardial biopsy was performed at the time of cardiac catheterization. Five hemodynamic indexes were used for functional assessment: ejection fraction, ratio of end-systolic stress to volume index, end-diastolic stress, time constant (T) of left ventricular pressure fall, and end-systolic stress. Six histologic findings (disarray of myofibers, hypertrophy of myofibers, scarcity of myofibrils, nuclear changes of myofibers, vacuolization of myofibers and proliferation of collagen fibers) were graded from (-) to (4+). Each finding was assigned to category (-) or (+) according to the absence or presence of significant abnormality. Ordinary statistical analysis revealed that, although ejection fraction was lower in category (+) for proliferation of collagen fibers, ratio of end-systolic to volume index was reduced for category (+) of hypertrophy of myofibers. A significant correlation was present between hypertrophy of myofibers and proliferation of collagen fibers by Spearman rank correlation. When principal component analysis was applied to the hemodynamic data, two principal components could be extracted. Fisher's discriminant analysis could clearly differentiate two categories (-) and (+) in the semiquantitative histologic finding of proliferation of collagen fibers. The analysis indicated that contractility was reduced with elevated afterload in that category (+). Thus, proliferation of collagen fibers may play a pivotal role in deteriorating contractility in patients with dilated cardiomyopathy.

Cardiomyopathy, Dilated↗
PubMed1987

In situ analysis with monoclonal antibodies of lymphocyte subsets in myocardial biopsies from patients with dilated cardiomyopathy and idiopathic (viral) myocarditis.

This light- and electron-microscopic immunohistochemical study using monoclonal antibodies analyzes of the in situ lymphocyte subsets in endomyocardial biopsies from 11 patients with dilated cardiomyopathy (DCM) and three patients with idiopathic (viral) myocarditis (MYO). In the DCM patients both Leu 2a+ cytotoxic/suppressor T cells (Tc/s) and Leu 3+ helper/inducer T cells (Th/i) were identifiable in the myocardial lesions, and mean Th/i/Tc/s (T4/T8) ratio was 0.7 +/- 0.6 (mean +/- SD). In 9 of the 11 DCM patients, Tc/s were more numerous than Th/i cells, so the T4/T8 ratio was less than 1.0. On the other hand, the T4/T8 ratios varied widely in the three MYO patients; one of them had marked mononuclear cell infiltrates with many Th/i in the inflammatory foci and a T4/T8 ratio of 2.6. Immunoelectron microscopy revealed some Th/i in close contact with macrophages. These T cells in the myocardium of DCM and MYO patients appeared to be in vivo effector cells playing an important role in cell-mediated immune responses.

Adult↗
PubMed1987

Intravenous isosorbide dinitrate infusion in the management of unstable angina pectoris refractory to conventional medical therapy.

During the past 2 years, 102 patients were treated for unstable angina pectoris (AP) in our department. Fifteen of them had recurrent chest pain at rest despite treatment with various anti-anginal agents, or prolonged chest pain unresponsive to sublingual nitroglycerin; they received intravenous isosorbide dinitrate (ISDN) infusion. A rapid bolus injection of 2 to 6 mg followed by an infusion of 2 to 5 mg/hr was given to 10 patients with acute chest pain, and 5 patients, who were free of chest pain at the time, but had repeated episodes of angina in the past 24 hours, were given ISDN infusion without a bolus injection. Chest pain disappeared completely in 13 patients, but recurred in 2 of them when the dose was tapered. Two other patients experienced recurrent chest pain during ISDN infusion, and additional boluses were given. The hospital course was uneventful in 11 patients. Four patients who had recurrent anginal attacks underwent emergency coronary cineangiography under intraaortic ballon counterpulsation and aorto-coronary bypass surgery. There were no hospital deaths, no one had subsequent acute myocardial infarctions, and only 2 patients had mild to moderate headache as a side effect. Although the patient population is small, intravenous ISDN infusion is useful in the management of severe unstable AP.

Acute Disease↗
PubMed1986

Small hepatocellular carcinomas in chronic liver disease: detection with SPECT.

Single-photon emission computed tomography (SPECT) performed using a rotating gamma camera was compared with alpha 1-fetoprotein (AFP) assay, conventional liver scintigraphy, ultrasound (US) imaging, computed tomography (CT), and selective celiac angiography in 40 patients with a total of 50 small hepatocellular carcinomas (HCCs; less than 5 cm). The detection rates of US and CT were determined on an initial screening study and on a second, more precisely focused study. The detection rate of small HCCs by the various modalities was as follows: AFP, 13%; liver scintigraphy, 36%; SPECT, 72%; initial screening US, 80%; second, more precise US studies, 94%; initial screening CT, 64%; second, more precise CT study, 82%; angiography, 88%. Although SPECT was inferior to the initial screening US examination in detecting HCCs less than 2 cm in size, its sensitivity was identical to that of the initial screening US study for detecting HCCs of 2-5 cm. The combination of SPECT and US was an excellent method for the early detection of HCCs, yielding a detection rate of 94%.

Aged↗
PubMed1986

Immunohistochemical study of the myocardium in murine Coxsackie B3 virus myocarditis using monoclonal antibodies--significance of Lyt 1 antigen-bearing lymphocytes in cell-mediated immunity.

This light- and electron-microscopic study using monoclonal antibodies provides an immunohistochemical demonstration of lymphocytes in situ in the myocardium in murine coxsackie B3 virus myocarditis. On the 7th and 9th days after virus inoculation, we observed many necrotic cardiocyte foci infiltrated with numerous inflammatory cells including macrophages and T lymphocytes. There were only a few Lyt 1-bearing lymphocytes in this phase of inoculation. On the 14th day there were many Lyt 1-bearing cells among the T cells in the foci. By immuno-electron microscopy, some Lyt 1-bearing T lymphocytes were seen in close contact with macrophages and/or other lymphocytes. These Lyt 1-bearing lymphocytes appeared to represent helper T cells, although Lyt 2.3+ lymphocytes were not examined. It is well known that activation of helper T cells leads to stimulation of B cells and cytotoxic T cells. It is assumed, therefore, that Lyt 1-bearing T lymphocytes that infiltrated into the myocardial foci play an important role in immune responsiveness at this stage of viral myocarditis.

Animals↗
PubMed1986

Histological findings of the right and left ventricular myocardium and clinical follow up in idiopathic ventricular tachycardia.

In order to evaluate the etiology of so-called idiopathic ventricular tachycardia, endomyocardial biopsies were performed in four patients with electrocardiographically documented recurrent and sustained ventricular tachycardia. During the episodes of ventricular tachycardia, standard ECG showed a QRS pattern of right bundle branch block with left axis deviation in two patients and left bundle branch block in two patients. The episodes were associated with palpitation, dyspnea and hypotension in all cases. No organic heart disease was detected by physical examination, chest X-ray films, echocardiograms, left ventriculograms or coronary cineangiograms. His bundle electrograms showed blocks at various sites in the atrioventricular conduction system. The biopsy specimens revealed nonspecific myocardial degeneration in the right and left ventricles. These findings suggest mild but wide-spread myocardial damage in both the working myocardium and the conduction system. The clinical course of these patients appeared benign according to follow-up data of one to nine years' duration. None developed overt clinical signs of dilated, hypertrophic or restrictive cardiomyopathy.

Adult↗
PubMed1985

Viral and idiopathic myocarditis in Japan: a questionnaire survey.

In order to study the current clinical status of viral and idiopathic myocarditis in Japan, we conducted a questionnaire survey and collected data for 218 cases from 62 institutions. The diagnosis was based on clinical and laboratory findings alone in 45% of the cases, and it included endomyocardial biopsy in 24% and autopsy in 9% of the patients. Endomyocardial biopsies were available in 40% of the patients; definite cellular infiltrations were identified in half the cases. Regardless of the biopsy findings or availability of biopsy, males predominated in the patient population; the mean age range was 30-39 years for both sexes. Cardiac symptoms and signs were common in addition to "common cold" symptoms; ECG abnormalities, leukocytosis, accelerated erythrocyte sedimentation rate, positive CRP, and increased cardiac enzyme levels were also very common in the acute phase of the disease. Serologic tests for virus titers, performed in 80% of the cases, were positive in 21%. There was no apparent correlation between serologic results and endomyocardial biopsy findings. In this survey, complete recovery occurred in 43%, cure with sequelae in 40%, recurrences in 3%, and death in 13% of the total patient population.

Adolescent↗
PubMed1985

Cell-mediated immunity in Coxsackie B3 virus myocarditis in mice--in situ characterization by monoclonal antibody of mononuclear cell infiltrates.

This light- and electron-microscopic study using monoclonal antibody and anti-immunoglobulin antibodies in murine Coxsackie B3 virus myocarditis provides an immunohistochemical demonstration of surface antigens of lymphocytes. On the 7th and 9th days after inoculation, many necrotic cardiocytes were surrounded by numerous cellular infiltrates, in which macrophages and T lymphocytes predominated, whereas immunoglobulin-bearing B lymphocytes represented a minority. Immuno-electron microscopy showed some T lymphocytes in close contact with other lymphocytes, macrophages, and the sarcolemma of cardiocytes. After the 30th day, significant numbers of T lymphocytes and macrophages were still identifiable in and around the fibrotic foci. Our study suggests that cell-mediated immunity plays a protective role by lysing and scavenging virus-infected cardiocytes and cell debris at least in the early stage of myocarditis. The residual T lymphocytes in the chronic stage suggest their involvement in sustained cardiocyte injury.

Animals↗
PubMed1985

Electron-microscopic and immunohistochemical studies on endomyocardial biopsies from a patient with eosinophilic endomyocardial disease.

Light- and electron-microscopic studies and immunohistochemical procedures were carried out on blood eosinophils and left ventricular endomyocardial biopsies from a 68-year-old man with an eosinophilia of 8.2 X 10(9)/l and congestive cardiac failure due to eosinophilic endomyocardial disease. Some blood eosinophils were vacuolated and degranulated, and reversal of the normal staining pattern of eosinophil granules was seen by means of electron microscopy. The biopsies showed degenerative changes in the cardiac myocytes, with interstitial fibrosis and infiltration by numerous eosinophils, mast cells, and macrophages. Eosinophils infiltrating the myocardium showed a decrease in the number of granules, many of which were indistinct or contained dissolving crystalloids, which occasionally were seen to be discharged onto the surface of adjacent cardiac myocytes. Immunohistochemical studies of the endomyocardial biopsies with a monoclonal antibody, which is specific for activated eosinophils and binds to the secreted forms of eosinophil cationic protein (ECP) and eosinophil protein-X (EP-X), demonstrated that the lesions contained numerous activated eosinophils and secreted ECP and EP-X. These findings support the concept that in eosinophilic endomyocardial disease, activated eosinophils infiltrate and degranulate in the myocardium, releasing eosinophil cationic proteins which then damage adjacent myocardial cells.

Aged↗
PubMed1985

Factors discriminating survivors and nonsurvivors in alcoholic heart disease.

Eighteen patients with dilated cardiomyopathy and a history of excessive ethanol intake were monitored for 3-98 months (mean 23 months). Six patients died (mean age 43.7 +/- 9.2 years) and 12 patients survived (mean age 48.8 +/- 9.5 years). Of the echocardiographic findings taken during heart failure, only the relative wall thickness to the internal dimension of the left ventricle (t/r ratio) differed significantly (survivors 0.33 +/- 0.77 vs. nonsurvivors 0.25 +/- 0.04, P less than 0.05). Of the hemodynamic data obtained after treatment of heart failure, left ventricular end-diastolic pressure differed significantly (survivors 6 +/- 2 vs. nonsurvivors 12 +/- 4 mmHg, P less than 0.001). The two groups could not be differentiated by ejection fraction, cardiac output, end-diastolic or end-systolic volumes, or semi-quantitative analysis of histologic findings obtained by right ventricular endomyocardial biopsy (light microscopy). Only two of six nonsurvivors (33%) succeeded in abstaining from alcohol, while eight of twelve survivors (67%) became teetotalers (P less than 0.05). Total abstinence from alcohol seems to be essential but was not necessarily followed by recovery in the most severe cases. Thus, the absence of adequate hypertrophy and high left ventricular filling pressure may predict the prognosis in alcoholic heart disease.

Adult↗