Masashi Inoue

The University of Tokyo, 白山, Tōkyō, Japan

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Publications (10)25.62 Total impact

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    ABSTRACT: Dilated cardiomyopathy (DCM), characterized by dilatation and dysfunction of the left ventricle, is an important cause of heart failure. Many mutations in various genes, including cytoskeletal protein genes and contractile protein genes, have been identified in DCM patients, but the mechanisms of how such mutations lead to DCM remain unknown. We established the mouse model of DCM by expressing a mutated cardiac alpha-actin gene, which has been reported in patients with DCM, in the heart (mActin-Tg). mActin-Tg mice showed gradual dilatation and dysfunction of the left ventricle, resulting in death by heart failure. The number of apoptotic cardiomyocytes and protein levels of p53 were increased in the hearts of mActin-Tg mice. Overexpression of Bcl-2 or downregulation of p53 decreased the number of apoptotic cardiomyocytes and improved cardiac function. This mouse model showed a decrease in myofilament calcium sensitivity and activation of calcium/calmodulin-dependent kinase IIdelta (CaMKIIdelta). The inhibition of CaMKIIdelta prevented the increase in p53 and apoptotic cardiomyocytes and ameliorated cardiac function. CaMKIIdelta plays a critical role in the development of heart failure in part by accumulation of p53 and induction of cardiomyocyte apoptosis in the DCM mouse model.
    Full-text · Article · Aug 2010 · Circulation
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    ABSTRACT: Purpose The aim of this study was to evaluate the validity and reliability of the Seattle Angina Questionnaire, Japanese version (SAQ-J) as a disease-specific health outcome scale in patients with coronary artery disease. Methods Patients with coronary artery disease were recruited from a university hospital in Tokyo. The patients completed self-administered questionnaires, and medical information was obtained from the subjects' medical records. Face validity, concurrent validity evaluated using Short Form 36 (SF-36), known group differences, internal consistency, and test-retest reliability were statistically analyzed. Results A total of 354 patients gave informed consent, and 331 of them responded (93.5%). The concurrent validity was mostly supported by the pattern of association between SAQ-J and SF-36. The patients without chest symptoms showed significantly higher SAQ-J scores than did the patients with chest symptoms in 4 domains. Cronbach's alpha ranged from .51 to .96, meaning that internal consistency was confirmed to a certain extent. The intraclass correlation coefficient of most domains was higher than the recommended value of 0.70. The weighted kappa ranged from .24 to .57, and it was greater than .4 for 14 of the 19 items. Conclusions The SAQ-J could be a valid and reliable disease-specific scale in some part for measuring health outcomes in patients with coronary artery disease, and requires cautious use.
    Full-text · Article · Jun 2010 · Asian Nursing Research
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    ABSTRACT: Assessing the health related quality of life (HRQOL) in patients with a disease specific scale is essential. The purpose of this study was to develop the Japanese version of the coronary revascularisation outcome questionnaire (CROQ), a disease-specific scale to measure HRQOL before and after coronary revascularisation. The English version of the questionnaire was translated into Japanese; some terms were revised, and some items were eliminated to suit the Japanese medical environment. Eight patients filled out the questionnaire, which was then analyzed for face validity. In the field study, subjects were recruited from a university hospital in Tokyo, and questionnaires were given to fill out. In terms of statistical analysis, factor analysis, internal consistency, known-groups validity, concurrent validity with using Short-Form36 (SF-36) and Seattle Angina Questionnaire-Japanese version (SAQ-J), and test-retest reliability were assessed. Informed consents were obtained from 356 patients, and out of 325 patients responded in the field study (91.3%). The factor structure of CROQ-Japanese version (CROQ-J) was similar to that of the original version. Cronbach's α ranged from 0.78 to 0.92. The concurrent validity was mostly supported by the pattern of association between CROQ-J, SAQ-J, and SF-36. Patients without chest symptoms had significantly higher scores of CROQ-J than those with chest symptoms. On the basis of analysis of the test-retest reliability, intra-class correlation coefficients were close to 0.70. The Japanese translation of CROQ is a valid and reliable scale for assessing the patient's HRQOL in CAD.
    Full-text · Article · May 2010 · European Journal of Cardiovascular Nursing

  • No preview · Article · Aug 2006 · Journal of Cardiac Failure
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    ABSTRACT: In a patient with Wolff-Parkinson-White syndrome whose accessory pathway was primarily capable of bidirectional conduction, antegrade conduction over the accessory pathway was transiently inhibited after rapid atrial or ventricular pacing or after spontaneous termination of atrioventricular reentrant tachycardia. Pacing rate and duration of tachycardia were related to the duration of the suppression of preexcitation, while the coupling interval of the first sinus beat to the last driven or tachycardia beat was irrelevant to the phenomenon. Thus, overdrive suppression of conduction may be the most likely mechanism of this phenomenon.
    No preview · Article · Dec 2000 · Japanese Heart Journal
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    ABSTRACT: We present a 57-year-old man with Wolff-Parkinson-White syndrome who exhibited a wide "gap" in retrograde conduction through a concealed atrioventricular accessory pathway. The appearance of the wide "gap" depended on the ventricular pacing sites. While ventricular extrastimuli at a basic cycle length of 600 msec from the right ventricular outflow tract consistently conducted to the atria, retrogradely through the accessory pathway, those from the right ventricular apex repeatedly revealed disappearance of the retrograde conduction at the wide coupling intervals from 550 to 380 msec. The mechanisms of this rare "gap"-like phenomenon are discussed in this paper.
    No preview · Article · Jul 1999 · Japanese Heart Journal
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    ABSTRACT: We report a 50-year-old man with a right ventricular structure causing an intraventricular pressure gradient. He had been diagnosed as vasculo-Behçet with a history of aphthous stomatitis and thrombophlebitis. He had also been suffering from atrial flutter and mild right-side heart failure. Echocardiography showed that there was an abnormal structure attached to the right ventricular free wall and protruding into the cavity, and that it caused the pressure gradient estimated to be approximately 19 mmHg. Chest X-ray computed tomography demonstrated that the structure was partially calcified. Magnetic resonance imaging depicted the structure separating the right ventricle into two chambers. Angiographic study revealed a markedly enlarged right atrium and a filling defect at the mid-portion of the right ventricle, which divided the right ventricular cavity into two parts. Hemodynamic study showed a slightly elevated right atrial pressure (mean 7 mmHg) and a peak-to-peak intraventricular pressure difference of 18 mmHg in the right ventricle. The diastolic pressure tracing of the right ventricular low pressure chamber showed a 'dip and plateau' pattern. Although the pathological features of the abnormal right ventricular structure in this case were not fully clarified, abnormal muscle bundle and/or endocardial fibrosis, which were reported to be associated with Behçet's disease, may have contributed to its generation.
    No preview · Article · Jul 1999 · Japanese Heart Journal
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    ABSTRACT: The purpose of this study was to determine whether aging influences the circadian variation of nonvalvular paroxysmal atrial fibrillation (AF). Among 31,200 consecutive Holter monitorings recorded between January 1988 and March 1997, we detected 212 patients who had paroxysmal AF in a drug-free state. These patients were divided into 2 groups according to their age: < or = 60 years old (94 patients) and >60 years old (118 patients). In each group, the sum of the duration of each AF episode and the probability of onset, maintenance, and termination of AF were determined as hourly data and compared between the 2 groups. The time distribution of AF showed remarkable age dependence, with a well-modulated and monophasic circadian rhythm in the younger group in contrast to a toneless triphasic rhythm in the older group. Among the onset, maintenance, and termination of the arrhythmia, the most obvious age-dependence was observed in the circadian variation of onset. In the younger group, there were triple peaks with the highest one in the night, whereas the older group exhibited a single peak in the daytime. In contrast, the probabilities of maintenance and termination showed similar circadian patterns between the groups, although their amplitudes were significantly reduced in the older group. Thus, aging significantly influenced the circadian variation of paroxysmal AF, with the most prominent effect on its onset, leading to more random time-distribution of AF with increasing age. These results extend to paroxysmal AF the concept that aging disrupts rhythmicity, suggesting age-dependent differences in its pathophysiology.
    No preview · Article · Jan 1999 · The American Journal of Cardiology
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    ABSTRACT: Pilsicainide, a class Ic agent, is known to be an effective drug particularly for treating atrial tachyarrhythmias. However, its electrophysiological effects on the atrium have not been well studied. To characterize the electrophysiologic effects of pilsicainide on atrial myocytes in class Ic drugs, we examined the effects of this drug on membrane currents in single rabbit atrial myocytes using the tight-seal whole cell voltage-clamp technique. Under the current-clamp condition, pilsicainide did not affect the action potential duration at therapeutic ranges (< or = 3 microM) and slightly shortened it at higher concentrations (> or = 10 microM). These observations were quite different from those with other class Ic agents including flecainide and propafenone which prolong the atrial action potential duration. The drug did not affect the resting membrane potential. Under the voltage-clamp condition, pilsicainide inhibited the transient outward current (Ito) that is more prominent in the atrium than in the ventricle in a concentration-dependent manner. However, in contrast to other class Ic agents, the inhibition to Ito by pilsicainide was observed only at much higher concentrations (IC50-300 microM) and did not affect the inactivation time-course of Ito. Moreover, the drug (10 microM) did not significantly affect the Ca2+, delayed rectifier K+, inward rectifying K+, acetylcholine-induced K+ or ATP-sensitive K+ currents. From these results pilsicainide could be differentiated as a pure Na+ channel blocker from other class Ic agents with diverse effects on membrane currents and should be recognized accordingly in clinical situations.
    No preview · Article · May 1998 · Japanese Heart Journal
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    ABSTRACT: ACE (angiotensin converting enzyme) gene genotypes have been shown to be a risk factor for development of left ventricular hypertrophy and cardiomyopathy, upon the assumption that the DD genotype is linked to higher cellular ACE activity leading to myocardial fibrosis. To test an analogous hypothesis that the DD genotype favors myocardial fibrosis in the atrium and thus promotes atrial fibrillation without any structural heart diseases, we determined the distribution of the ACE gene genotypes in 77 patients with lone atrial fibrillation and investigated the effects of the ACE genotypes on the clinical characteristics of atrial fibrillation. The distribution of ACE genotypes was not significantly different between the patients and healthy volunteers. Also, the ACE gene genotypes did not affect the types of atrial fibrillation and the age at the onset of atrial fibrillation. Thus, these results refuted the hypothesis of possible relationships between ACE genotypes and lone atrial fibrillation through myocardial fibrosis, and indicated some unknown differences between the atrium and ventricle.
    No preview · Article · Oct 1997 · Japanese Heart Journal