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Biomedical subjects

M Hiroe

Publications and source records attributed to M Hiroe.

At least 145 records · Page 8Linked to original sources
PubMed1991

Endothelin-1 induces hypertrophy with enhanced expression of muscle-specific genes in cultured neonatal rat cardiomyocytes.

To determine whether endothelin-1 (ET-1) induces hypertrophy of cardiomyocytes, the effects of ET-1 on the expression of muscle-specific genes and a proto-oncogene, c-fos, in cultured neonatal rat cardiomyocytes were examined by Northern blot analysis. ET-1 (10(-7) M) induced about twofold to fourfold increases in the gene expression of myosin light chain 2, alpha-actin, and troponin I after 6 hours, which continued up to 24 hours. The ET-1-induced increases in mRNA levels for these muscle-specific genes were dose dependent (10(-9) to 10(-7) M). Run-on transcriptional assay showed that the changes in mRNA level for three muscle-specific genes were regulated, at least in part, at the transcriptional level. 12-O-Tetradecanoylphorbol 13-acetate (TPA), a potent protein kinase C activator, and the Ca2+ ionophore ionomycin also increased mRNA levels of three muscle-specific genes. ET-1, TPA, and ionomycin similarly induced the expression of c-fos after 30 minutes, which returned to an undetectable level after 6 hours. ET-1 remarkably and dose-dependently stimulated accumulation of total inositol phosphates in cardiomyocytes. Morphometrical evaluation showed that ET-1 significantly increased surface area of cardiomyocytes without cell proliferation. ET-1 also dose-dependently stimulated the synthesis of protein and DNA, which was unaffected by the L-type calcium channel blocker nicardipine. These data suggest that ET-1 induces hypertrophy of cardiomyocytes associated with the induction of muscle-specific gene transcripts through the possible involvement of protein kinase C activation or intracellular Ca2+ mobilization.

Animals↗
PubMed1991

Reduced high harmonic power spectra in patients with old myocardial infarction.

Acceleration of blood flow ejected from the ventricle into the aorta and the hydraulic power state of blood flow in the aorta may be affected by asynchronous or locally depressed contraction of the left ventricle as well as by arterial impedance. In order to evaluate the effect of an infarcted heart on the hydraulic power state of blood flow, the aortic input impedance spectrum and the hydraulic power spectrum were calculated from simultaneous recordings of pulsatile aortic pressure and flow velocity at the aortic root in 6 normal controls (group 1), 6 patients with old myocardial infarction (OMI) without aneurysm (group 2), and 6 patients of OMI with aneurysm (group 3). The ratios (Rh) of power in high harmonics to that of fundamental harmonics, that is, Rh = (E2 + E3 + ...E10)/E1, where E represents hydraulic power and the numbers represent harmonic numbers, were 0.64 +/- 0.17, 0.23 +/- 0.09, and 0.22 +/- 0.10 in groups 1, 2, and respectively (p less than 0.001 between groups 1 and 2; p less than 0.001, between groups 1 and 3). As the acceleration of ejecting flow of blood by the left ventricle is inversely related with arterial impedance, Rh will be also inversely related with arterial impedance. Then, the product of Rh and the characteristic impedance (Zc) would be an indicator of the left ventricular contractility. In fact, the products were 64 +/- 15, 32 +/- 14, and 31 +/- 13 dyne.sec.cm-5 in groups 1, 2, and 3 respectively (p less than 0.005, between groups 1 and 2; p less than 0.005, between groups 1 and 3). These results suggest that asynchronous or locally depressed contractions of the left ventricular wall are closely related to depressed Rh and further to depressed values of the products of Rh and Zc. It is concluded that analysis of the power spectrum of blood flow in the root of the aorta provides information of the left ventricular contractility in connection with arterial impedance.

Blood Flow Velocity↗
PubMed1991

[Right ventricular infarction following acute inferior myocardial infarction confirmed by dual isotope single photon emission computed tomography (SPECT) of [99mTc] pyrophosphate and [201Tl] chloride].

A 56-year-old man, complaining of severe substernal chest pain, was admitted. In this patient, right ventricular infarction following by acute inferior myocardial infarction was suggested by serial enzymes, electrocardiogram, echocardiogram, and hemodynamic data, but it was not confirmed. A dual isotope SPECT with 99mTc-pyrophosphate and 201Tl-Cl was performed and color-coded tomograms were obtained. It showed a characteristic image of right ventricular infarction, especially in the short axis view right ventricular infarction looked like shape of a tongue which protruded from left ventricle. We concluded that though the diagnosis of right ventricular infarction is difficult, a dual isotope SPECT is a useful method because it shows a characteristic image.

Diphosphates↗
PubMed1990

Beat-to-beat evaluation of cardiac function during recovery from upright bicycle exercise in patients with coronary artery disease.

The purpose of this study was to evaluate the time course of cardiac function during recovery from upright bicycle exercise in patients with coronary artery disease. Twelve patients with coronary artery disease performed a symptom-limited exercise test on a cycle ergometer. Left ventricular function was continuously monitored during exercise and recovery with a computerized cadmium telluride detector following the intravenous injection of technetium-labeled red blood cells. Although the end-diastolic volume (153.4 +/- 76.1 ml) and end-systolic volume (100.5 +/- 67.3 ml) at the end of exercise were significantly higher than the respective resting values, stroke volume (52.8 +/- 16.1 ml) and ejection fraction (38.0 +/- 12.2%) were not different from the respective resting values. The recovery of cardiac output was relatively slow compared with that of heart rate, because stroke volume rose sharply early in recovery. The rise in stroke volume was chiefly a result of a significant decrease in end-systolic volume between 1 and 4 minutes of recovery. These changes may result from an immediate afterload reduction coupled with a relatively slow decrease in sympathetic stimulation. The time course of cardiac function during recovery from exercise in cardiac patients is substantially different from that of normal subjects and may be a sensitive way to evaluate the peripheral vascular function and deteriorated cardiac function in cardiac patients.

Adult↗
PubMed1990

Increased levels of beta-human atrial natriuretic peptide-like immunoreactivity in chronically overloaded atrial tissue.

The levels and molecular form of atrial natriuretic peptide-like immunoreactivity (ANP-LI) in human atrial tissue were investigated. The levels of right atrial ANP-LI were significantly higher in mitral disease than in other cardiac or noncardiac diseases. The increased ANP-LI was mainly accounted for by an increase in beta-human ANP-LI (beta-hANP-LI). Both total ANP-LI and beta-hANP-LI levels were associated with the presence of atrial fibrillation and with increased atrial pressure. Plasma beta-hANP-LI levels were also increased in mitral disease. These results suggest that human atrium with hemodynamic overloads is characterized by increased tissue levels of ANP and by a shift to the beta-hANP form.

Adult↗
PubMed1990

Myocardial perfusion after aortic implantation for anomalous origin of the left coronary artery from the pulmonary artery.

Postoperative myocardial perfusion and function were evaluated using thallium-201 myocardial imaging and technetium-99m cardiac pool imaging in five patients with an anomalous left coronary artery arising from the pulmonary artery. The patients underwent reimplantation of the left coronary artery at an age ranging from 10 months to 13 years. Postoperative electrocardiographic and radionuclide studies were performed both at rest and during stress 1 to 4 years after the operation. Electrocardiograms which were abnormal preoperatively returned to normal after surgery except that the T wave in lead aVL remained negative. Postoperatively, left ventricular ejection fraction measured by technetium-99m cardiac pool imaging was normal in all patients. Postoperative thallium-201 myocardial imaging, however, showed a perfusion defect with incomplete redistribution at the high-lateral or antero-lateral segment in all patients after a stress test. These data suggest that although myocardial ischaemic change decreases and global cardiac function improves after establishment of a dual coronary artery system, severe myocardial damage remains at the high-lateral or antero-lateral segment.

Adolescent↗
PubMed1990

Effects of isosorbide dinitrate on exercise capacity in cardiac patients--relationship between oxygen uptake responses and hemodynamic effects.

Acute effects of oral isosorbide dinitrate on exercise capacity were evaluated in 14 patients with chronic heart disease measuring the anaerobic threshold and left ventricular function during exercise. A symptom-limited exercise test was performed on a bicycle ergometer with work rates increased by 1W every 6 seconds. Left ventricular function was continuously monitored with a computerized cadmium telluride detector following the intravenous injection of technetium-labeled red blood cells. Thirty minutes after the control exercise test, patients were given isosorbide dinitrate, 5 mg orally. The second exercise test was performed 30 min later. Isosorbide dinitrate improved the anaerobic threshold from 715.4 +/- 172.9 to 774.9 +/- 173.5 ml/min (p less than 0.01) and ejection fraction at peak exercise from 36.7 +/- 11.6 to 39.9 +/- 12.3% (p less than 0.05). However, there was no significant change in maximum work rate or peak oxygen uptake. Those patients for whom isosorbide dinitrate resulted in a 10% or greater improvement in the anaerobic threshold had both higher pre-treatment ejection fractions and greater increases in peak exercise ejection fraction following isosorbide dinitrate. Measurements of the anaerobic threshold and left ventricular function during exercise may be useful in the evaluation of the efficacy of vasodilators in cardiac patients.

Anaerobiosis↗
PubMed1990

Arrhythmogenic right ventricular dysplasia with sick sinus syndrome and atrioventricular conduction disturbance.

Although arrhythmogenic right ventricular dysplasia (ARVD) is believed to involve primarily the right ventricle, left ventricular abnormalities have also been described. We report a case of ARVD with abnormalities of the sinus node, right atrium and atrioventricular node. The biopsies taken from the right atrium and the right ventricle showed replacement of myocardium by fibrous tissue. The pathologic changes of this disease process may extend into the atrium and atrioventricular node.

Atrioventricular Node↗
PubMed1990

Significant myocardial pathology and increase of alpha 1-adrenergic receptor number affecting the arrhythmogenic condition in cases with ventricular tachycardia.

To study the pathogenesis of idiopathic ventricular tachycardia with left bundle branch block morphology (LBBB-VT), histopathological findings in 34 patients and adrenergic receptor (AR) density obtained by micro-autoradiography in 11 patients were analyzed, using endomyocardial biopsy samples. According to the ventricular volume, we divided the patients into 3 groups. Group A patients (n = 8) were diagnosed as having arrhythmogenic right ventricular dysplasia (ARVD) showing right ventricular enlargement, group B patients (n = 7) showed decreased left ventricular function and/or enlarged left ventricle, and group C (n = 19) included patients with idiopathic ventricular tachycardia (VT) without enlargement or dysfunction of either ventricle. Histologically, there was a high incidence of significant pathology showing myocardial hypertrophy, degeneration, abnormal branching, and interstitial fibrosis in all groups (group A, 100%; group B, 86%; group C, 56%). There was a higher incidence of fatty tissue infiltration in groups A (100%), B (71%), C (48%) than in the control groups. As for AR, specific grains of alpha 1- and beta-AR were 23.0, and 18.3 (grains/25 x 25 mm square) respectively, in patients with LBBB-VT. The number of alpha 1 grains in patients with LBBB-VT was apparently higher than in the control group, sick sinus syndrome (SSS; 11.2), and the beta-AR density in the LBBB-VT group was the same as in the control group (SSS; 15.4). We concluded that the significant pathology in cases with VT might affect the arrhythmogenic condition. Moreover, these results suggested that the increase in the number of alpha 1-AR might have a great influence in idiopathic VT.

Adult↗
PubMed1990

Clinicopathological analysis of a patient with hypereosinophilic syndrome who demonstrated disseminated eosinophilic infiltration in various organs at autopsy.

A case (41 year old man) of idiopathic hypereosinophilic syndrome is presented. Typical eosinophilic endocarditis with restrictive cardiac failure and ventricular thrombosis was demonstrated by various clinical investigations, including cardiac pool scan and biopsy. The patient died after 22 months, and an autopsy revealed disseminated eosinophilic infiltration in the pancardium of the whole heart, aorta, main pulmonary artery, liver, and spleen.

Adult↗
PubMed1990

High incidence of significant pathology in endomyocardial biopsy and familial occurrence in cases with arrhythmia and/or conduction disturbance.

In our series of studies of cardiomyopathy with endomyocardial biopsy in 1500 cases, we have noticed that there were a certain number of patients with arrhythmias and/or conduction disturbance who showed no evidence of hypertrophic or dilated form of caridiomyopathy but showed significant pathology in the biopsy. Significant pathology was determined when the biopsy findings from the right atrium and the right ventricle showed apparent pathology such as interstitial fibrosis, myocyte degeneration, and fragmentation of muscle bundles. Among 226 biopsied patients in whom arrhythmia and/or conduction disturbance were the main clinical feature, 85 patients (38%) demonstrated significant pathology in their biopsy. Familial occurrence was note-worthy among these patients. We propose that these cases should be grouped as nonhypertrophic, nondilated, and nonrestrictive cardiomyopathy, and suggest the term electric disturbance type of cardiomyopathy (ECM).

Arrhythmias, Cardiac↗
PubMed1990

Usefulness of electrophysiologic study and endomyocardial biopsy in differentiating arrhythmogenic right ventricular dysplasia from idiopathic right ventricular tachycardia.

Fifteen patients with right ventricular tachycardia without evidence of coronary artery disease or dilated or hypertrophic cardiomyopathy were evaluated, by means of electrophysiologic study and right ventricular endomyocardial biopsy. Six cases were diagnosed as definite arrhythmogenic right ventricular dysplasia (ARVD), while 2 cases without characteristic findings of ARVD by noninvasive studies and angiography were diagnosed as probable ARVD on the basis of their electrophysiologic and histopathologic data. In conclusion, ARVD is relatively common as an etiology of right ventricular tachycardia, and detailed electrophysiologic study and endomyocardial biopsy appear to be useful for diagnosis of ARVD.

Adolescent↗
PubMed1990

Hemodynamic and scintigraphic improvement after steroid therapy in a case with acute eosinophilic heart disease.

A 70-year-old woman with active hypereosinophilic myocarditis presented with high fever and heart failure. Repeated right ventricular endomyocardial biopsies and 201-T1 myocardial scans before and after steroid therapy suggested that this treatment reversed the cardiac injury. Patients with hypereosinophilia may die from complications of eosinophilic infiltration and fibrosis in target organs, especially the heart. The findings in this patient suggest that steroids have benefit in this disease, at least in the short term.

Acute Disease↗
PubMed1990

Immunohistochemical study on human atrial natriuretic polypeptide in the ventricle of hearts with endocardial fibroelastosis.

The presence and distribution of human atrial natriuretic polypeptide (ANP) were investigated immunohistochemically in the ventricles of hearts of 14 cases with endocardial fibroelastosis and 15 cases with noncardiac disease in children. Paraffin sections of autopsied hearts with endocardial fibroelastosis were stained with polyclonal antibodies against human alpha-ANP. Immunoreactive myocytes were clearly demonstrated in the ventricles of 10 hearts with endocardial fibroelastosis. The distribution of ANP-positive cells was most frequent in the inner one-third of the left ventricle. No ANP immunoreactivity was detected in any heart in cases with noncardiac disease. The left ventricular volume index of hearts with ANP-positive cells was larger than that with ANP-negative cells. The mean diameter of ANP-positive myocytes was greater than that of ANP-negative myocytes. These results suggest that ANP expression in ventricular myocytes is related to severe dilatation of the ventricular cavity and to development of myocardial hypertrophy in endocardial fibroelastosis.

Atrial Natriuretic Factor↗
PubMed1990

[Radionuclide assessment of cardiac involvement in patients with sarcoidosis].

This study was aimed to determine whether nuclear methods were useful for examining cardiac pathology and for making a decision of corticosteroid therapy in patients with sarcoidosis. Thirty six patients were divided into two groups; GpA consisted of 19 patients with cardiac sarcoidosis and abnormal ECG findings, and GpB of 17 patients with sarcoidosis without ECG abnormalities. Cardiac uptake of 67Ga-citrate in 2 and 99mTc-PYP in one of GpA was observed and steroid therapy resulted in the disappearance of the uptake. 201Tl-CL cardiac tomograms disclosed perfusion defects in 10 of 14 patients (71%) in GpA, including defects with redistribution in 8 of the 10 pts, but only one case in GpB. Radionuclide ventriculography using 99mTc-RBC revealed abnormal response of left ventricular (LV) function to exercise and LV dysfunction in GpA. These data suggest that nuclear study is a useful tool for diagnosing cardiac sarcoidosis, evaluating therapeutic effectiveness and long-term follow-up in patients with sarcoidosis.

Adult↗
PubMed1990

Histopathological assessment of endomyocardial biopsy in children: I. Semiquantitative study on the hypertrophy of cardiac myocytes.

Over 200 endomyocardial biopsies in pediatric patients have been performed since 1962, and an appropriate interpretation of myocardial hypertrophy in biopsy specimens at different ages is now necessary. The diameter of myocytes was measured in 108 biopsy specimens and 209 autopsy specimens from pediatric cases. There was a gradual increase in the myocyte diameter according to age in the biopsy and autopsy specimens. The diameter became adult size at 13 to 15 years of age in the right ventricle and at 9 to 15 years in the left ventricle. The myocyte size of diseased hearts was greater than that of normal hearts at each age. The coefficient of variance of the mean myocyte diameter in heart muscle disease, including hypertrophic cardiomyopathy and dilated cardiomyopathy, was greater than in other hearts. These results suggested that it is possible to ascertain myocardial hypertrophy by measuring the diameter of cardiac myocytes. A proposed grading system of the degree of myocyte hypertrophy for the biopsy specimens at various pediatric ages is reported.

Adolescent↗