Ryoichi Nagatomi

Ryoichi Nagatomi


Research Focus & Metrics

Academic Career Length

37Years (1990-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 February 2006 in The American Journal of Clinical Nutrition
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Journal Article
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SKShinichi Kuriyama
Shinichi Kuriyama
AHAtsushi Hozawa
Atsushi Hozawa
KOKaori Ohmori
Kaori Ohmori
TSTaichi Shimazu
Taichi Shimazu
TMToshifumi Matsui
Toshifumi Matsui
ITIchiro Tsuji
Ichiro Tsuji
Background: Although considerable experimental and animal evidence shows that green tea may possess potent activities of neuroprotection, neurorescue, and amyloid precursor protein processing that may lead to cognitive enhancement, no human data are available. Objective: The objective was to examine the association between green tea consumption and cognitive function in humans. Design: We analyzed cross-sectional data from a community-based Comprehensive Geriatric Assessment (CGA) conducted in 2002. The subjects were 1003 Japanese subjects aged ≥70 y. They completed a self-administered questionnaire that included questions about the frequency of green tea consumption. We evaluated cognitive function by using the Mini-Mental State Examination with cutoffs of <28, <26, and <24 and calculated multivariate-adjusted odds ratios (ORs) of cognitive impairment. Results: Higher consumption of green tea was associated with a lower prevalence of cognitive impairment. At the <26 cutoff, after adjustment for potential confounders, the ORs for the cognitive impairment associated with different frequencies of green tea consumption were 1.00 (reference) for ≤3 cups/wk, 0.62 (95% CI: 0.33, 1.19) for 4–6 cups/wk or 1 cup/d, and 0.46 (95% CI: 0.30, 0.72) for ≥2 cups/d (P for trend = 0.0006). Corresponding ORs were 1.00 (reference), 0.60 (95% CI: 0.35, 1.02), and 0.87 (95% CI: 0.55, 1.38) (P for trend = 0.33) for black or oolong tea and 1.00 (reference), 1.16 (95% CI: 0.78, 1.73), and 1.03 (95% CI: 0.59, 1.80) (P for trend = 0.70) for coffee. The results were essentially the same at cutoffs of <28 and <24. Conclusion: A higher consumption of green tea is associated with a lower prevalence of cognitive impairment in humans.

1 October 2010 in Journal of Urology
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Journal Article
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HNHaruo Nakagawa
Haruo Nakagawa
Kaijun NiuKaijun Niu
Kaijun Niu
AHAtsushi Hozawa
Atsushi Hozawa
YIYoshihiro Ikeda
Yoshihiro Ikeda
YKYasuhiro Kaiho
Yasuhiro Kaiho
YAYoichi Arai
Yoichi Arai
We evaluated the association of nocturia with fracture and death in a large, community based sample of Japanese individuals 70 years old or older. The baseline in this population based study was determined in 2003 by an extensive health interview with each participant. In this study we followed 784 individuals with a mean ± SD age of 76.0 ± 4.6 years (range 70 to 97). Information on mortality and fracture during the study period was provided by the National Health Insurance system and details on fractures were collected from medical records. We compared the risk of bone fracture and death with or without nocturia in a multivariate Cox proportional hazard model. Nocturia (2 or greater voids per night) was present in 359 of the 784 participants (45.7%). Fracture was observed in 41 cases, including 32 fall related cases. For all fractures and fall related fractures with nocturia the HR was 2.01 (95% CI 1.04-3.87) and 2.20 (95% CI 1.04-4.68, each p = 0.04). Death occurred in 53 cases. The mortality rate in individuals with nocturia was significantly higher than in those without nocturia. For mortality in patients with nocturia the age-gender adjusted HR was 1.91 (95% CI 1.07-3.43, p = 0.03). Even when further adjusted for diabetes, smoking status, history of coronary disease, renal disease and stroke, tranquilizers, hypnotics and diuretics, the positive relationship was unchanged (HR 1.98, 95% CI 1.09-3.59, p = 0.03). During a 5-year observation period elderly individuals with nocturia were at greater risk for fracture and death than those without nocturia.

1 June 2015 in Games for Health Journal
Verified
Journal Article
Closed access
KSKeizo Sato
Keizo Sato
KKKaoru Kuroki
Kaoru Kuroki
SSSyuko Saiki
Syuko Saiki
RNRyoichi Nagatomi
Ryoichi Nagatomi
Many issues prevent elderly individuals from exercising in daily life. There is a need for a system that allows elderly individuals to engage in exercise regularly at a low cost. We developed an exergame that uses a Kinect(®) sensor (Microsoft Corp., Redmond, WA) and conducted a randomized controlled trial of the effects of using this exergame on muscle strength and balance in healthy elderly individuals. We enrolled 57 healthy elderly individuals and randomly divided them into an intervention group (n=29) and a control group (n=28) using a table of random numbers. All participants underwent gait analyses and were examined using the Berg Balance Scale (BBS), Functional Reach Test (FRT), and the 30-second chair-stand (CS-30) test before the intervention. Participants in the intervention group played the exergame once or twice a week, up to a total of 24 times. The tests were repeated after intervention, and the scores were compared with those obtained before intervention. Our results indicated that walking, muscle strength, and motor function improved in participants in the intervention group. Decreased double standing time (P=0.03), minimum foot clearance (P=0.04), BBS scores (P<0.01), CS-30 scores (P<0.01), and FRT scores (P<0.01) significantly improved in the intervention group compared with values in the control group. The Kinect-based exergame developed in this study was found to be effective in improving walking, muscular strength, and balance in elderly people.

1 June 2016 in Molecular and Cellular Biology
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Journal Article
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AUAkira Uruno
Akira Uruno
YYYoko Yagishita
Yoko Yagishita
FKFumiki Katsuoka
Fumiki Katsuoka
YKYasuo Kitajima
Yasuo Kitajima
ANAki Nunomiya
Aki Nunomiya
MYMasayuki Yamamoto
Masayuki Yamamoto
Nrf2 (NF-E2-related-factor-2) contributes to the maintenance of glucose homeostasis in vivo. Nrf2 suppresses blood glucose levels by protecting pancreatic β-cells from oxidative stress and improving peripheral tissue glucose utilization. To elucidate the molecular mechanisms by which Nrf2 contributes to the maintenance of glucose homeostasis, we generated skeletal muscle (SkM)-specific Keap1-knockout (Keap1MuKO) mice that express abundant Nrf2 in SkM and then examined Nrf2-target gene expression in this tissue. In Keap1MuKO mice, blood glucose levels were significantly downregulated, and the levels of glycogen branching enzyme (Gbe1) and muscle-type phosphorylase-b kinase α-subunit (Phka1) mRNAs, along with those of glycogen branching enzyme (GBE) and the phosphorylase-b kinase α-subunit (PhKα) protein, were significantly upregulated in mouse SkM. Consistent with this result, chemical Nrf2-inducers promoted Gbe1 and Phka1 mRNA expression in both mouse SkM and C2C12 myotubes. Chromatin-immunoprecipitation analysis demonstrated that Nrf2 binds the Gbe1 and Phka1 upstream promoter regions. In Keap1MuKO mice, muscle glycogen content was strongly reduced, and forced GBE expression in C2C12 myotubes promoted glucose uptake. Therefore, our results demonstrate that Nrf2-induction in SkM increases GBE and PhKα expression and reduces muscle glycogen content, resulting in improved glucose tolerance. Our results also indicate that Nrf2 differentially regulates glycogen metabolism in SkM and liver.

1 December 2009 in The American Journal of Clinical Nutrition
Verified
Journal Article
Open access
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Kaijun NiuKaijun Niu
Kaijun Niu
AHAtsushi Hozawa
Atsushi Hozawa
SKShinichi Kuriyama
Shinichi Kuriyama
SESatoru Ebihara
Satoru Ebihara
HGHui Guo
Hui Guo
ITIchiro Tsuji
Ichiro Tsuji
Background: Green tea is reported to have various beneficial effects (eg, anti–stress response and antiinflammatory effects) on human health. Although

16 May 2005 in Psychiatry and Clinical Neurosciences
Verified
Journal Article
Open access
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SAShuichi Awata
Shuichi Awata
TSToru Seki
Toru Seki
YKYayoi Koizumi
Yayoi Koizumi
SSSoichiro Sato
Soichiro Sato
AHAtsushi Hozawa
Atsushi Hozawa
ITIchiro Tsuji
Ichiro Tsuji
Abstract  The objective of the present study was to evaluate the association between suicidal ideation and potentially related factors in an elderly urban Japanese population. This was a community‐based, cross‐sectional study. Urban community residents aged 70 years or more were interviewed regarding suicidal ideation and sociodemographic and health‐related variables. Subjects with depressive symptoms underwent further evaluation by psychiatrists using criteria of the Diagnostic and Statistical Manual of Mental Disorders, 4th edition. Associations were evaluated using univariate and multivariate logistic regression analyses. Of the 1145 eligible participants, 52 (4.5%) reported thoughts of suicide. Of 143 subjects with depressive symptoms (Geriatric Depression Scale, 14+), 22 (15.4%) reported suicidal ideation over a 2‐week period. After controlling for depressive symptoms, lack of social support and impaired instrumental activities of daily living were significantly associated with thoughts of suicide. After controlling for the potentially associated factors detected in the univariate analysis, depressive symptoms were strongly associated with thoughts of suicide. In the elderly with depressive symptoms, mental disorders, including depressive and alcohol‐related disorders, were significantly associated with suicidal ideation over a 2‐week period. In the urban community setting, screening for lack of social support, impaired instrumental activities of daily living, and depressive symptoms, followed by diagnostic evaluation for mental disorders, particularly for depressive syndromes and alcohol‐related disorders, may provide a practical and effective means of identifying elders at high risk of suicide.