Ken-ichiro Okada

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BACKGROUND The endoplasmic reticulum (ER) is recognized as an organelle that participates in folding secretory and membrane proteins. The ER responds to stress by upregulating ER chaperones, but prolonged and/or excess ER stress leads to apoptosis. However, the potential role of ER stress in pathophysiological hearts remains unclear. METHODS AND RESULTS(More)
The ubiquitin-proteasome system contributes to regulation of apoptosis degrading apoptosis-regulatory proteins. Marked accumulation of ubiquitinated proteins in cardiomyocytes of human failing hearts suggested impaired ubiquitin-proteasome system in heart failure. Since cardiomyocyte apoptosis contributes to the progression of cardiac dysfunction in(More)
BACKGROUND The endoplasmic reticulum (ER) responds to various stresses by upregulation of ER chaperones, but prolonged ER stress eventually causes apoptosis. Although apoptosis is considered to be essential for the progression and rupture of atherosclerotic plaques, the influence of ER stress and apoptosis on rupture of unstable coronary plaques remains(More)
OBJECTIVES We investigated the effects of erythropoietin (EPO) on neovascularization and cardiac function after myocardial infarction (MI). BACKGROUND Erythropoietin exerts antiapoptotic effects and mobilizes endothelial progenitor cells (EPCs). METHODS We intravenously administered EPO (1,000 IU/kg) immediately [EPO(0) group], 6 h [EPO(6h) group], or 1(More)
BACKGROUND Adenosine inhibits proliferation of cardiac fibroblasts and hypertrophy of cardiomyocytes, both of which may play crucial roles in cardiac remodeling. In the present study, we investigated whether chronic stimulation of adenosine receptors begun after myocardial infarction (MI) prevents cardiac remodeling. METHODS AND RESULTS MI was produced in(More)
BACKGROUND Apoptosis may contribute to the development of heart failure, but the role of apoptotic signaling initiated by the endoplasmic reticulum in this condition has not been well clarified. METHODS AND RESULTS In myocardial samples from patients with heart failure, quantitative real-time polymerase chain reaction revealed an increase in messenger RNA(More)
The prevalence of atrial fibrillation (AF) increases in patients with hypertension. Angiotensin II is involved in structural atrial remodeling, which contributes to the onset and maintenance of AF in paced animal models. We investigated the role of angiotensin II in atrial structural remodeling in rats with hypertension. Ten-week-old male Wistar-Kyoto rats(More)
The unfolded protein response (UPR) is triggered to assist protein folding when endoplasmic reticulum (ER) function is impaired. Recent studies demonstrated that ER stress can also induce cell-specific genes. In this study, we examined whether X-box binding protein 1 (XBP1), a major UPR-linked transcriptional factor, regulates the expression of brain(More)
BACKGROUND Migration, proliferation, and matrix-degrading protease expression of smooth muscle cells (SMCs) are major features of intimal hyperplasia after vascular injury. Although MEK kinase 1 (MEKK1) has been shown to regulate cell migration and urokinase plasminogen activator (uPA) expression, the precise role of MEKK1 in this process remains unknown.(More)
BACKGROUND Extracorporeal circulation induces a systemic inflammatory response, which may adversely affect organ function. One manifestation of this response is increased fibrinolysis. Antifibrinolytic drugs such as aprotinin and epsilon-aminocaproic acid have been effective in reducing fibrinolysis and blood loss after extracorporeal circulation; however,(More)