Hiroyuki Okumura

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Ghrelin is an acylated peptide with growth-hormone-releasing activity (1). It was first isolated from rat and human stomach during the search for an endogenous ligand to the " orphan " G-protein-coupled receptor, growth hormone secretagogue receptor (2). The peptide contains 28 amino acids, and n-octanoylation of the Ser-3 hydroxyl group is necessary for(More)
Insulin-like growth factor (IGF)-1 appears to play an important role in cardiac hypertrophy or remodeling. However, the role of endogenous IGF-1 in the growth of cardiac myocytes and fibroblasts remains unclear. This study investigated the major site of the production of cardiac IGF-1 and the local effects of endogenous IGF-1 secreted from cardiac cells. A(More)
This study proposes a method to decompose a signal into a set of periodic signals with time-varying amplitude. The proposed method imposes a penalty on the resultant periodic subsignals in order to improve the sparsity of the decomposition. This penalty is defined as the sum of the l 2 norms of the resultant periodic subsignals to find the shortest path to(More)
In this paper, we propose a single-channel speech separation method by using a sparse decomposition with a periodic signal model. In our separation method, a mixture of speeches is approximated with periodic signals with time-varying amplitude. The decomposition with the periodic signal model is performed under a sparsity penalty. Due to the sparsity(More)
Background—Infusion of adrenomedullin (AM) has beneficial hemodynamic effects in patients with heart failure. However, the effect of AM on myocardial ischemia/reperfusion remains unknown. Methods and Results—Male Sprague-Dawley rats were exposed to a 30-minute period of ischemia induced by ligation of the left coronary artery. They were randomized to(More)
Background—Ghrelin is a novel growth hormone (GH)-releasing peptide, isolated from the stomach, that may also cause a positive energy balance by stimulating food intake and inducing adiposity. We sought to investigate the pathophysiology of ghrelin in the cachexia associated with chronic heart failure (CHF). Methods and Results—Plasma ghrelin was measured(More)
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