Akira Ohtahara

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BACKGROUND Structural changes in the number, size, and shape of mitochondria (mt) have been observed in the atrial muscles of patients with atrial fibrillation (AF) and of animals with rapid atrial pacing, however, it is not known whether the mitochondrial function is impaired in human atrium with AF. MATERIALS AND METHODS We determined adenine(More)
BACKGROUND The angiotensin receptor blocker losartan inhibited urate transporter 1 (URAT1) according to in vitro experiments. However, it is still unknown whether the inhibitory effect of losartan on URAT1 contributes to its uricosuric action in humans. METHODS Thirty-two patients with hypertension and nine patients with idiopathic renal hypouricemia(More)
BACKGROUND The relationship between plasma uridine levels and blood pressure (BP), and indicators of muscular purine degradation and insulin resistance (IR) has been evaluated in hypertensive (HT) patients. METHODS AND RESULTS In 36 HT patients and 10 normotensive subjects, seated BP was measured, and blood samples were drawn after overnight fast. In 18(More)
AMP deaminase (AMPD) plays a central role in preserving the adenylate energy charge in myocytes following exercise and in producing intermediates for the citric acid cycle in muscle. Prior studies have demonstrated that AMPD1 binds to myosin heavy chain (MHC) in vitro; binding to the myofibril varies with the state of muscle contraction in vivo, and binding(More)
The characteristics of urate metabolism in renal hypouricemic patients with hematuria were studied to clarify the risk factors for hematuria in patients with renal hypouricemia. In 16 Japanese patients with isolated renal hypouricemia, urate metabolism was measured using the urate clearance study and the subtype of renal hypouricemia [defective presecretory(More)
OBJECTIVE To compare the effects of amlodipine and nifedipine on heart rate and parameters of sympathetic nerve activity during the acute and chronic treatment periods in order to elucidate their influence on cardiovascular outcome. DESIGN A randomized and single-blind study. METHODS We performed 24 h ambulatory electrocardiography and blood pressure(More)
BACKGROUND A relationship between constitutional signs in patients with cardiac myxoma and interleukin-6 has been noted. However, there is little information about characteristics of cardiac myxomas associated with constitutional signs. HYPOTHESIS The objective of this study was to clarify the characteristics of myxoma patients who had constitutional(More)
OBJECTIVE Hyperuricemia is associated with the vascular injury of hypertension, and purine oxidation may play a pivotal role in this association, but the pathophysiology is not fully understood. We tested the hypothesis that in hypertensive patients, the excess amount of the purine metabolite, hypoxanthine, derived from skeletal muscles, would be oxidized(More)
Few potassium channel genes have been isolated in the guinea-pig despite detailed electrophysiological characterization of potassium channels in the guinea-pig heart. We obtained partial clones of Shaker-type potassium channel genes in the guinea-pig and demonstrated their tissue distribution. Partial clones of the Shaker-type potassium channel genes were(More)
Recently, clinical diagnostic methods for heart disease, especially echocardiography, have remarkably progressed and the incidence of cardiac tumors increased. This study investigated the characteristics of tumors in 115 patients with primary cardiac tumor, diagnosed histologically in 1993-1994, in collaboration with 126 university hospitals in Japan.(More)