Nobuhiko Akazawa
University of Tsukuba
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Featured researches published by Nobuhiko Akazawa.
Nutrition Research | 2012
Nobuhiko Akazawa; Youngju Choi; Asako Miyaki; Yoko Tanabe; Jun Sugawara; Ryuichi Ajisaka; Seiji Maeda
Vascular endothelial function is declines with aging and is associated with an increased risk of cardiovascular disease. Lifestyle modification, particularly aerobic exercise and dietary adjustment, has a favorable effect on vascular aging. Curcumin is a major component of turmeric with known anti-inflammatory and anti-oxidative effects. We investigated the effects of curcumin ingestion and aerobic exercise training on flow-mediated dilation as an indicator endothelial function in postmenopausal women. A total of 32 postmenopausal women were assigned to 3 groups: control, exercise, and curcumin groups. The curcumin group ingested curcumin orally for 8 weeks. The exercise group underwent moderate aerobic exercise training for 8 weeks. Before and after each intervention, flow-mediated dilation was measured. No difference in baseline flow-mediated dilation or other key dependent variables were detected among the groups. Flow-mediated dilation increased significantly and equally in the curcumin and exercise groups, whereas no changes were observed in the control group. Our results indicated that curcumin ingestion and aerobic exercise training can increase flow-mediated dilation in postmenopausal women, suggesting that both can potentially improve the age-related decline in endothelial function.
American Journal of Physiology-heart and Circulatory Physiology | 2014
Tomoko Matsubara; Asako Miyaki; Nobuhiko Akazawa; Youngju Choi; Song-Gyu Ra; Koichiro Tanahashi; Hiroshi Kumagai; Satoshi Oikawa; Seiji Maeda
The Klotho gene is a suppressor of the aging phenomena, and the secretion as well as the circulation of Klotho proteins decrease with aging. Although habitual exercise has antiaging effects (e.g., a decrease in arterial stiffness), the relationship between Klotho and habitual exercise remains unclear. In the present study, we investigated the effect of habitual exercise on Klotho, with a particular focus on arterial stiffness. First, we examined the correlation between plasma Klotho concentration and arterial stiffness (carotid artery compliance and β-stiffness index) or aerobic exercise capacity [oxygen uptake at ventilatory threshold (VT)] in 69 healthy, postmenopausal women (50-76 years old) by conducting a cross-sectional study. Second, we tested the effects of aerobic exercise training on plasma Klotho concentrations and arterial stiffness. A total of 19 healthy, postmenopausal women (50-76 years old) were divided into two groups: control group and exercise group. The exercise group completed 12 wk of moderate aerobic exercise training. In the cross-sectional study, plasma Klotho concentrations positively correlated with carotid artery compliance and VT and negatively correlated with the β-stiffness index. In the interventional study, aerobic exercise training increased plasma Klotho concentrations and carotid artery compliance and decreased the β-stiffness index. Moreover, the changes in plasma Klotho concentration and arterial stiffness were found to be correlated. These results suggest a possible role for secreted Klotho in the exercise-induced modulation of arterial stiffness.
Applied Physiology, Nutrition, and Metabolism | 2012
Asako Miyaki; Seiji Maeda; Youngju Choi; Nobuhiko Akazawa; Yoko Tanabe; Ryuichi Ajisaka
Chronic inflammation that occurs with aging is one of the risk factors for cardiovascular disease. Regular exercise may prevent cardiovascular morbidity by decreasing chronic systematic inflammation. Additionally, excess inflammation can be reduced by the anti-inflammatory protein pentraxin 3 (PTX3). Thus, both habitual exercise and PTX3 have an anti-inflammatory effect. However, it is unclear whether regular exercise leads to increased plasma PTX3 concentration. In the present study, we investigated the effects of regular aerobic exercise on plasma PTX3 concentration in middle-aged and elderly women. Twenty-two postmenopausal women (60 ± 6 years) were randomly divided evenly into 2 groups (i.e., exercise intervention and control). Subjects in the exercise group completed 2 months of regular aerobic exercise training (walking and cycling, 30-45 min, 3-5 days·week⁻¹). Before and after the intervention, we evaluated plasma PTX3 concentration, peak oxygen uptake, blood chemistry, and arterial distensibility (carotid arterial compliance and β-stiffness) in all participants. There were no significant differences in baseline parameters between the 2 groups. Plasma PTX3 concentration was significantly increased in the exercise group after the intervention (p < 0.05). High-density lipoprotein cholesterol, peak oxygen uptake, and arterial compliance were also significantly increased (p < 0.05), while β-stiffness was markedly decreased (p < 0.01) after the intervention. On the other hand, there was no change in the parameters tested in the control group. This study demonstrates that regular aerobic exercise increases plasma PTX3 concentration with improvement of high-density lipoprotein cholesterol, peak oxygen uptake, and arterial distensibility in postmenopausal women.
American Journal of Hypertension | 2013
Asako Miyaki; Seiji Maeda; Youngju Choi; Nobuhiko Akazawa; Miki Eto; Kiyoji Tanaka; Ryuichi Ajisaka
BACKGROUND Obesity and increased arterial stiffness are independent risk factors for cardiovascular disease. The degree of arterial stiffness in obese individuals is greater than that in normal-weight subjects. Pentraxin 3 (PTX3) is mainly produced by vascular tissues and exerts a cardioprotective effect. However, the relationship between PTX3 and arterial stiffness in obese individuals has not yet been clarified. In this study, we examined the relationships between obesity, arterial stiffness, and PTX3 levels in 282 subjects. METHODS All participants were classified as normal weight, overweight, or obese on the basis of their body mass index. We measured the brachial-ankle pulse wave velocity (baPWV; an index of arterial stiffness) and plasma PTX3 concentrations in all subjects. Additionally, the carotid-femoral PWV (cfPWV) was measured in 173 subjects. RESULTS We found that baPWV and cfPWV in overweight and obese subjects were significantly higher than those in normal-weight subjects. Plasma PTX3 concentrations in normal-weight subjects were significantly higher than those in overweight and obese subjects. Moreover, PTX3 had a significant negative correlation with baPWV. However, stepwise multivariable linear regression analysis did not indicate any associations between these parameters. CONCLUSIONS Arterial stiffness is increased in overweight and obese individuals. The increase in arterial stiffness may, at least in part, be associated with an obesity-related reduction in plasma PTX3 concentrations.
American Journal of Hypertension | 2014
Koichiro Tanahashi; Nobuhiko Akazawa; Asako Miyaki; Youngju Choi; Song-Gyu Ra; Tomoko Matsubara; Hiroshi Kumagai; Satoshi Oikawa; Seiji Maeda
BACKGROUND Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase, increase with advancing age and menopausal status. ADMA plays a role in endothelial dysfunction and increasing arterial stiffness. Regular aerobic exercise has a positive effect on arterial function (i.e., arterial compliance). This study investigated the effects of aerobic exercise training on plasma ADMA concentrations and arterial compliance in postmenopausal women. METHODS Thirty postmenopausal women were divided into 2 groups: an exercise group (n = 20) and a control group (n = 10). Subjects in the exercise group completed 12 weeks of aerobic exercise training (65%-80% of maximal heart rate, 40-60 min/day, 3-6 days/week). Before and after each intervention, plasma ADMA concentrations and carotid arterial compliance were measured in all participants. RESULTS The baseline plasma ADMA concentrations, carotid arterial compliance, and most other key dependent variables did not differ between the 2 groups. In the exercise group, carotid arterial compliance significantly increased after exercise intervention (P < 0.01), and plasma ADMA concentrations significantly decreased (P < 0.05). In addition, changes in carotid arterial compliance after the exercise intervention were inversely correlated with changes in plasma ADMA concentrations (r = -0.367; P < 0.05). CONCLUSIONS We demonstrated that aerobic exercise training significantly decreased plasma ADMA concentrations with increase in carotid arterial compliance in postmenopausal women. These results suggest that reduction in ADMA may play an important role in the aerobic exercise training-induced increase in arterial compliance.
Blood Pressure Monitoring | 2013
Ryota Higashino; Asako Miyaki; Hiroshi Kumagai; Youngju Choi; Nobuhiko Akazawa; Song-Gyu Ra; Yoko Tanabe; Miki Eto; Rina So; Kiyoji Tanaka; Ryuichi Ajisaka; Seiji Maeda
ObjectiveIt has recently been recognized that increased central blood pressure is a predictor of cardiovascular disease. Central blood pressure is higher in obese individuals than in nonobese individuals. However, the effect of lifestyle modification on central systolic blood pressure in obese individuals is unclear. The aim of this study was to determine whether lifestyle modification decreases central blood pressure in overweight and obese men. MethodsThirty-nine overweight and obese men (age, 49±2 years; BMI, 30±1 kg/m2) were recruited into our study. We measured central systolic blood pressure and brachial-ankle pulse wave velocity (baPWV), an index of arterial stiffness, before and after a 12-week lifestyle modification that included aerobic exercise and dietary modification. ResultsAfter the 12-week program, body mass, BMI, and waist circumstance decreased significantly. Central systolic blood pressure and baPWV were significantly decreased after the lifestyle modification in overweight and obese men. Furthermore, there was a significant correlation between the lifestyle modification-induced change in central systolic blood pressure and that in baPWV. ConclusionThis study showed for the first time that lifestyle modification-induced weight loss decreases central systolic blood pressure in overweight and obese men. The decrease in central systolic blood pressure was associated with the reduction in arterial stiffness. These results suggest that lifestyle modification-induced reduction in arterial stiffness may contribute toward the decreased central systolic blood pressure in overweight and obese men.
Journal of Strength and Conditioning Research | 2016
Youngju Choi; Nobuhiko Akazawa; Asako Zempo-Miyaki; Song-Gyu Ra; Hitoshi Shiraki; Ryuichi Ajisaka; Seiji Maeda
Abstract Choi, Y, Akazawa, N, Zempo-Miyaki, A, Ra, S-G, Shiraki, H, Ajisaka, R, and Maeda, S. Acute effect of high-intensity eccentric exercise on vascular endothelial function in young men. J Strength Cond Res 30(8): 2279–2285, 2016—Increased central arterial stiffness is as an independent risk factor for cardiovascular disease. Evidence regarding the effects of high-intensity resistance exercise on vascular endothelial function and central arterial stiffness is conflicting. The purpose of this study was to examine the effects of acute high-intensity eccentric exercise on vascular endothelial function and central arterial stiffness. We evaluated the acute changes in endothelium-dependent flow-mediated dilation (FMD), low-flow–mediated constriction (L-FMC), and arterial stiffness after high-intensity eccentric exercise. Seven healthy, sedentary men (age, 24 ± 1 year) performed maximal eccentric elbow flexor exercise using their nondominant arm. Before and 45 minutes after eccentric exercise, carotid arterial compliance and brachial artery FMD and L-FMC in the nonexercised arm were measured. Carotid arterial compliance was significantly decreased, and &bgr;-stiffness index significantly increased after eccentric exercise. Brachial FMD was significantly reduced after eccentric exercise, whereas there was no significant difference in brachial L-FMC before and after eccentric exercise. A positive correlation was detected between change in arterial compliance and change in FMD (r = 0.779; p ⩽ 0.05), and a negative correlation was detected between change in &bgr;-stiffness index and change in FMD (r = −0.891; p < 0.01) with eccentric exercise. In this study, acute high-intensity eccentric exercise increased central arterial stiffness; this increase was accompanied by a decrease in endothelial function caused by reduced endothelium-dependent vasodilation but not by a change in endothelium-dependent vasoconstriction.
Frontiers in Physiology | 2015
Nobuhiko Akazawa; Song-Gyu Ra; Jun Sugawara; Seiji Maeda
Central arterial blood pressure (BP) is more predictive of future cardiovascular events than is brachial BP because it reflects the BP load imposed on the left ventricle with greater accuracy. However, little is known about the effects of exercise training on central hemodynamic response to acute exercise. The purpose of the present study was to determine the influence of an aerobic exercise regimen on the response of aortic BP after a single aerobic exercise in postmenopausal women. Nine healthy postmenopausal women (age: 61 ± 2 years) participated in a 12-week aerobic exercise training regimen. Before and after the training, each subjects performed a single bout of cycling at ventilatory thresholds for 30 min. We evaluated the post-exercise aortic BP response, which was estimated via the general transfer function from applanation tonometry. After the initial pre-training aerobic exercise session, aortic BP did not change significantly: however, aortic pulse pressure and augmentation pressure were significantly attenuated after the single aerobic exercise session following the 12-week training regimen. The present study demonstrated that a regular aerobic exercise training regimen induced the post-exercise reduction of aortic pulse pressure and augmentation pressure. Regular aerobic exercise training may enhance post-exercise reduction in aortic BP.
Advances in Experimental Medicine and Biology | 2015
Song-Gyu Ra; Nobuhiko Akazawa; Youngju Choi; Tomoko Matsubara; Satoshi Oikawa; Hiroshi Kumagai; Koichiro Tanahashi; Hajime Ohmori; Seiji Maeda
The purpose of the present study was to clarify the effects of taurine supplementation on delayed onset muscle soreness (DOMS) and muscle damage after high-intensity eccentric exercise (ECC) in healthy young men. Twenty-nine healthy young men were recruited and randomly assigned to receive either placebo (n = 14) or taurine supplementation (n = 15) in a double-blind manner. Participants ingested either 2.0 g of placebo or taurine supplement three times a day for 2 weeks before and 3 days after high-intensity ECC. Two weeks after starting supplementation, participants performed two sets of unilateral maximal-effort ECC of the elbow flexors on a Biodex isokinetic dynamometer. Each set consisted of 20 contractions with each contraction lasting 3 s and repeated every 9 s, and a 4 min period of rest in between sets. DOMS (evaluated by the visual analogue scale), upper arm circumference (CIR), elbow range of motion (ROM), and parameters of muscle damage including serum myoglobin (Mb) and creatine kinase (CK) levels, were measured before exercise and for 4 days after ECC. The severity of DOMS 2 days after ECC was significantly less in the taurine group than in the placebo group. The area under the curve for DOMS was also significantly smaller in the taurine group. However, taurine supplementation did not affect muscle damage (CIR, ROM, and serum Mb level and CK activity) after ECC. These results suggest that taurine supplementation effectively decreases DOMS after high-intensity ECC in young healthy men.
Life Sciences | 2014
Koichiro Tanahashi; Nobuhiko Akazawa; Asako Miyaki; Youngju Choi; Song-Gyu Ra; Tomoko Matsubara; Hiroshi Kumagai; Satoshi Oikawa; Takashi Miyauchi; Seiji Maeda
AIMS Asymmetric dimethylarginine (ADMA) is an endogenous competitive inhibitor of nitric oxide (NO) synthase, an enzyme responsible for the generation of NO. Plasma concentrations of ADMA increase in the elderly and in postmenopausal women. In fact, an elevated ADMA level is a risk factor of cardiovascular disease. Aerobic exercise has a beneficial effect on cardiovascular disease. However, the relationship between ADMA and aerobic fitness is unknown. The aim of this study was to determine whether plasma ADMA concentrations correlate with aerobic fitness levels in postmenopausal women. MAIN METHODS Thirty healthy postmenopausal women aged 50-76 years participated in this study. We measured plasma concentrations of ADMA and oxygen consumption at the ventilatory threshold (VO2VT) as an index of aerobic fitness. Subjects were divided into the low aerobic fitness (Low fitness) and high aerobic fitness (High fitness) groups, and the dividing line was set at the median VO2VT value. KEY FINDINGS VO2VT was significantly higher in the High fitness group than in the Low fitness group (P<0.01). The plasma ADMA concentrations in the High fitness group were significantly lower than those in the Low fitness group (P<0.05). There was a negative correlation between plasma ADMA concentrations and VO2VT (r=-0.532, P<0.01). SIGNIFICANCE We found that plasma ADMA concentrations were associated with aerobic fitness in postmenopausal women. The results of this study suggest that habitual aerobic exercise may decrease plasma ADMA concentrations.
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National Institute of Advanced Industrial Science and Technology
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