Motohisa Osaka

Nippon Veterinary and Life Science University

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Age-adjusted level of circulating elastin as a cardiovascular risk factor in medical check-up individuals

Journal of Cardiovascular Medicine (2013)

Hiroyuki Yamanaka Motohisa Osaka Morimasa Takayama Kazuo Munakata Jun Nejima

The level of circulating soluble elastin (CSE) is reported to increase proportionally with the degree of clinical atherosclerosis; however, its diagnostic use is limited because CSE also increases with age. We aimed to investigate whether alterations in CSE concentrations are implicated in potential cardiovascular dysfunctions (indicated by standard physiological parameters) in medical check-up individuals, taking age into consideration.In a total of 531 individuals (age 20-89 years), CSE levels were correlated most significantly with age. The groups of male and female individuals were each further divided into two subgroups: those with higher and those with lower CSE levels than the reference values determined by polynomial regression.Male participants with lower CSE levels (n = 128) than the age-adjusted reference baseline levels showed higher serum glucose (P < 0.008), uric acid (P < 0.008) and triglyceride (P < 0.02) levels than those with higher CSE levels (n = 126). However, most of the parameters tested in female participants with lower CSE levels (n = 140) were statistically comparable to those with higher CSE levels (n = 137). The ratio of CSE level to the age-adjusted reference level was calculated in each of the male participants, and declines in the ratio were significantly correlated with increases of serum glucose, uric acid and triglyceride levels (P < 0.005, P < 0.02 and P < 0.006, respectively).The decrease in age-adjusted CSE levels is a potential indicator of eventual cardiovascular dysfunction in medical check-up individuals, as predicted by the risk factors dyslipidemia, hyperuricemia or diabetes.

Dyslipidemia

10.2459/jcm.0b013e328360940b

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Citations (10)

Ensho Saisei (2006)

Tomoyuki Yambe Yoshio Hori Y Shiraishi Kazumitsu Sekine Atsushi Iguchi

In artificial internal organs, smaller is better. And an important issue is bio affinity. From these points of view, Regenerative medicine and Nano technology are very useful technology. In Tohoku University, various artificial internal organ research including Artificial esophagus, Artificial Myocardium, and Artificial sphincter based on 21 COE program. Ideal artificial organs may be embodied in future.

Artificial urinary sphincter

Artificial heart

Artificial life

10.2492/jsir.26.35

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AZELNIDIPINE PREVENTED THE REFLEX INCREASES IN HEART RATE AND SYMPATHETIC NERVE ACTIVITY IN CONSCIOUS HYPERTENSIVE RATS

Journal of Hypertension (2004)

Toshiko Onami Hideki Kumagai Kotaro Sakata Chie Takimoto Motohisa Osaka

Onami, Toshiko; Kumagai, H.; Sakata, K.; Takimoto, C.; Osaka, M; ligaya, K.; Saruta, T. Author Information

Sympathetic activity

Sympathetic nerve

Sympathetic nervous system

10.1097/00004872-200402001-00262

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Citations (0)

Probability Theory Predicts That Chunking into Groups of Three or Four Items Increases the Short-Term Memory Capacity

Applied Mathematics (2014)

Motohisa Osaka

Short-term memory allows individuals to recall stimuli, such as numbers or words, for several seconds to several minutes without rehearsal. Although the capacity of short-term memory is considered to be 7 ± 2 items, this can be increased through a process called chunking. For example, in Japan, 11-digit cellular phone numbers and 10-digit toll free numbers are chunked into three groups of three or four digits: 090-XXXX-XXXX and 0120-XXX-XXX, respectively. We use probability theory to predict that the most effective chunking involves groups of three or four items, such as in phone numbers. However, a 16-digit credit card number exceeds the capacity of short-term memory, even when chunked into groups of four digits, such as XXXX-XXXX-XXXX-XXXX. Based on these data, 16-digit credit card numbers should be sufficient for security purposes.

Chunking (psychology)

Numerical digit

10.4236/am.2014.510140

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Depressed Heart Rate Variability and Arterial Baroreflex in Conscious Transgenic Mice With Overexpression of Cardiac G _sα

Circulation Research (1998)

Masami Uechi Kuniya Asai Motohisa Osaka Amelia Smith Naoki Sato

Abstract —Recently, we developed a transgenic mouse with cardiac-specific G sα overexpression (TG mouse), which exhibits enhanced postsynaptic β-adrenergic receptor signaling, ultimately developing a cardiomyopathy. The goal of the present study was to determine whether cardiac G sα overexpression alters autonomic cardiovascular control, which could shed light on the mechanism responsible for the later development of cardiomyopathy. Mean arterial pressure was increased ( P <.05) in conscious, chronically instrumented TG mice (123±1 mm Hg) compared with age-matched wild-type (WT) control mice (103±1 mm Hg). Respiratory frequency was increased ( P <.05) in TG mice (269±26/min) compared with WT mice (210±20/min). By use of telemetric techniques, baseline heart rate (HR) was elevated ( P <.05) in conscious, untethered TG mice (696±13 bpm) compared with WT mice (568±28 bpm). Intrinsic HR, after propranolol and atropine or after ganglionic blockade with hexamethonium, was not different between TG and WT mice. Both the normal minute-to-minute and circadian variations of HR observed in WT mice were markedly blunted in TG mice. HR variability was assessed by the time-domain and frequency-domain methods. At baseline, time-domain analysis indices were reduced ( P <.05) in TG mice compared with WT mice. Although the low frequency (LF) component was higher ( P <.05) than the high frequency (HF) component in WT mice, the LF component was less ( P <.05) than the HF component in TG mice. In addition, arterial baroreflex regulation of HR was markedly blunted in TG mice in response to both nitroglycerin-induced hypotension and phenylephrine-induced hypertension. The reduced LF/HF ratio in TG mice was surprising in view of enhanced β-adrenergic signaling and may be due to reduced neural tone secondary to the elevated arterial pressure or alterations in arterial baroreflex control. Dobutamine infusion in WT mice also resulted in depressed HR variability. The combination of elevated baseline HR, arterial pressure, and respiratory frequency suggests that enhanced β-adrenergic signaling in TG mice results in reduced HR variability, in terms of both minute-to-minute variability and the lack of circadian variations in HR. The lack of normal HR variability in general and the failure of HR to decline, even during sleep, may actually be critical mechanisms contributing to the ultimate development of cardiomyopathy in these animals.

10.1161/01.res.82.4.416

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Citations (150)

α-ADRENERGIC FUNCTION IN THE PATIENTS WITH CARDIAC ARRHYTHMIA : WITH REFFERENCE TO THE SYMPTOMS RELATED TO CEREBRAL ISCHEMIA

Japanese Circulation Journal-english Edition (1994)

Takuya Ono Atsunobu Nomura Shin Matsumoto Kazuko Ohmura Toshihiko Ohara

Cardiac arrhythmia

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Importance of rostral ventrolateral medulla neurons in determining efferent sympathetic nerve activity and blood pressure

Hypertension Research (2011)

Hiroo Kumagai Naoki Oshima Tomokazu Matsuura Kamon Iigaya Masaki Imai

Accentuated sympathetic nerve activity (SNA) is a risk factor for cardiovascular events. In this review, we investigate our working hypothesis that potentiated activity of neurons in the rostral ventrolateral medulla (RVLM) is the primary cause of experimental and essential hypertension. Over the past decade, we have examined how RVLM neurons regulate peripheral SNA, how the sympathetic and renin-angiotensin systems are correlated and how the sympathetic system can be suppressed to prevent cardiovascular events in patients. Based on results of whole-cell patch-clamp studies, we report that angiotensin II (Ang II) potentiated the activity of RVLM neurons, a sympathetic nervous center, whereas Ang II receptor blocker (ARB) reduced RVLM activities. Our optical imaging demonstrated that a longitudinal rostrocaudal column, including the RVLM and the caudal end of ventrolateral medulla, acts as a sympathetic center. By organizing and analyzing these data, we hope to develop therapies for reducing SNA in our patients. Recently, 2-year depressor effects were obtained by a single procedure of renal nerve ablation in patients with essential hypertension. The ablation injured not only the efferent renal sympathetic nerves but also the afferent renal nerves and led to reduced activities of the hypothalamus, RVLM neurons and efferent systemic sympathetic nerves. These clinical results stress the importance of the RVLM neurons in blood pressure regulation. We expect renal nerve ablation to be an effective treatment for congestive heart failure and chronic kidney disease, such as diabetic nephropathy.

Rostral ventrolateral medulla

Sympathetic nervous system

Medulla

Sympatholytics

10.1038/hr.2011.208

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Citations (154)

Fluctuation of heart rate and autonomic nervous system.

Journal of Nippon Medical School (1995)

Motohisa Osaka

ている.

10.1272/jnms1923.62.71

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Citations (3)

Correlation Dimension Analysis of Heart Rate Variability in Nonsustained Ventricular Tachycardia

Japanese Circulation Journal-english Edition (1994)

Motohisa Osaka Hirokazu Saitoh Noriko Sasabe Atsunobu Nomura Hirotsugu Atarashi

Correlation dimension

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Autonomic nervous activity preceding paroxysmal tachycardic arrhythmias.

Japanese Journal of Electrocardiology (1993)

Hirokazu Saitoh Noriko Sasabe Motohisa Osaka Takeshi Ino Hirotsugu Atarashi

交感神経緊張亢進をはじめとする自律神経活動の変化が心室頻拍の発症に重要な役割を果たすといわれている.一方, 発作性心房細動の一部には副交感神経緊張亢進が誘因となるものがあるといわれている.しかし頻脈発症時の自律神経活動につき客観的に検討した報告はない.そこで, 非持続性心室頻拍 (NSVT) , 発作性心房細動 (PAF) を対象に, 頻脈発症前の自律神経活動を心拍変動周波数分析により検討し, 交感神経型 (S群) , 副交感神経型 (P群) , 両神経型 (SP群) に分類し, 比較検討した.NSVTではS群29%, P群34%, SP群17%, PAFではS群36%, P群29%, SP群9%であった.NSVTではS群で発作直前の心拍数, VTレートが速く, 発症時間も昼間に集中しており, 交感神経緊張亢進を反映するものと考えられた.PAFではP群でAF時の心拍数が遅かったのみだが, S群ではβ遮断剤有効例が多く, 本法により薬剤効果の予測が可能と考えられた.

10.5105/jse.13.181

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Citations (3)