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Dive into the research topics where Namio Higa is active.

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Featured researches published by Namio Higa.


Diabetic Medicine | 2004

A single dose of nateglinide improves post‐challenge glucose metabolism and endothelial dysfunction in Type 2 diabetic patients

Michio Shimabukuro; Namio Higa; Nobuyuki Takasu; Tatsuya Tagawa; Shinichiro Ueda

Aims  This randomized crossover placebo‐controlled study aimed to assess the efficacy of nateglinide, a phenylalanine‐derived insulin secretagogue, on forearm endothelial function in diabetic subjects before and after an oral glucose load.


Diabetes Care | 2011

Impaired Glucose Tolerance, but Not Impaired Fasting Glucose, Underlies Left Ventricular Diastolic Dysfunction

Michio Shimabukuro; Namio Higa; Tomohiro Asahi; Ken Yamakawa; Yoshito Oshiro; Moritake Higa; Hiroaki Masuzaki

OBJECTIVE Glucose intolerance is recognized as a predictor of congestive heart failure (CHF). However, the association of postprandial hyperglycemia or fasting hyperglycemia with CHF has not been clarified. We determined the impact of the total spectrum of glucose abnormalities on left ventricular (LV) geometry and diastolic function. RESEARCH DESIGN AND METHODS Two hundred and eighty-seven Japanese subjects who visited the university hospital to be checked for glucose intolerance or known type 2 diabetes were consecutively recruited. Participants underwent an oral glucose tolerance test if they had no history of diabetes, and LV geometry and LV systolic and diastolic function were analyzed by Doppler echocardiography. RESULTS The frequency of LV diastolic dysfunction in subjects with normal glucose tolerance, impaired fasting glucose (IFG), impaired glucose tolerance (IGT), newly detected diabetes, and known diabetes were 13, 22, 50, 51, and 61%, respectively (χ2 = 54.2, P < 0.0001). IGT was a predictor for LV diastolic dysfunction after adjusting for age, sex, systolic blood pressure, and heart rate (odds ratio 3.43 [95% CI 1.09–11.2]), but IFG was not (0.49 [0.06–3.08]). IGT was a predictor after adjusting for established CHF risk factors but was no longer significant after adjusting for BMI and homeostasis model assessment of insulin resistance. CONCLUSIONS In this hospital-based registry of subjects without CHF, the prevalence of LV diastolic dysfunction was higher in subjects with IGT but not in those with IFG. Results suggest that IGT, as well as newly detected and known diabetes, could be linked to an increased risk of cardiovascular events, partly through LV diastolic dysfunction.


Diabetes, Obesity and Metabolism | 2007

Diagnostic utility of brain-natriuretic peptide for left ventricular diastolic dysfunction in asymptomatic type 2 diabetic patients

Michio Shimabukuro; Namio Higa; Yoshito Oshiro; Tomohiro Asahi; Nobuyuki Takasu

Aim:  Left ventricular (LV) diastolic dysfunction has been reported to be prevalent in diabetic subjects, but this recognition could often be missed. We evaluated prevalence of LV diastolic dysfunction and diagnostic utility of brain‐natriuretic peptide (BNP) in asymptomatic patients with type 2 diabetes mellitus.


Cardiology Research and Practice | 2012

Eicosapentaenoic Acid Supplementation Changes Fatty Acid Composition and Corrects Endothelial Dysfunction in Hyperlipidemic Patients

Ken Yamakawa; Michio Shimabukuro; Namio Higa; Tomohiro Asahi; Kageyuki Ohba; Osamu Arasaki; Moritake Higa; Yoshito Oshiro; Hisashi Yoshida; Tohru Higa; Taro Saito; Shinichiro Ueda; Hiroaki Masuzaki; Masataka Sata

We investigated the effects of purified eicosapentaenoic acid (EPA) on vascular endothelial function and free fatty acid composition in Japanese hyperlipidemic subjects. In subjects with hyperlipidemia (total cholesterol ≥220 mg/dL and/or triglycerides ≥150 mg/dL), lipid profile and forearm blood flow (FBF) during reactive hyperemia were determined before and 3 months after supplementation with 1800 mg/day EPA. Peak FBF during reactive hyperemia was lower in the hyperlipidemic group than the normolipidemic group. EPA supplementation did not change serum levels of total, HDL, or LDL cholesterol, apolipoproteins, remnant-like particle (RLP) cholesterol, RLP triglycerides, or malondialdehyde-modified LDL cholesterol. EPA supplementation did not change total free fatty acid levels in serum, but changed the fatty acid composition, with increased EPA and decreased linoleic acid, γ-linolenic acid, and dihomo-γ-linolenic acid. EPA supplementation recovered peak FBF after 3 months. Peak FBF recovery was correlated positively with EPA and EPA/arachidonic acid levels and correlated inversely with dihomo-γ-linolenic acid. EPA supplementation restores endothelium-dependent vasodilatation in hyperlipidemic patients despite having no effect on serum cholesterol and triglyceride patterns. These results suggest that EPA supplementation may improve vascular function at least partly via changes in fatty acid composition.


International Journal of Cardiology | 2013

Defects of vascular nitric oxide bioavailability in subjects with impaired glucose tolerance: a potential link to insulin resistance.

Michio Shimabukuro; Namio Higa; Tatsuya Tagawa; Ken Yamakawa; Masataka Sata; Shinichiro Ueda

tolerance: A potential link to insulin resistance Michio Shimabukuro ⁎, Namio Higa , Tatsuya Tagawa , Ken Yamakawa , Masataka Sata , Shinichiro Ueda d a Department of Cardio-Diabetes Medicine, The University of Tokushima Graduate School of Health Biosciences, Tokushima, Japan b Department of Cardiovascular Medicine, The University of Tokushima Graduate School of Health Biosciences, Tokushima, Japan c Division of Endocrinology, Diabetes and Metabolism, Hematology, Rheumatology, Second Department of Internal Medicine, University of the Ryukyus Graduate School of Medicine, Okinawa, Japan d Department of Clinical Pharmacology and Therapeutics, University of the Ryukyus Graduate School of Medicine, Okinawa, Japan


Circulation | 2016

Respiratory Collapse of the Inferior Vena Cava Reflects Volume Shift and Subsequent Fluid Refill in Acute Heart Failure Syndrome.

Tomohiro Asahi; Marohito Nakata; Namio Higa; Mamoru Manita; Kazuhiko Tabata; Michio Shimabukuro

BACKGROUND Fluid redistribution rather than fluid accumulation plays an important role in the development of acute heart failure (HF) syndrome. Patients with fluid redistribution develop acute HF without prominent volume overload. We investigated volume status by measuring the diameter of the inferior vena cava (IVC) and examining variations in hemoglobin and hematocrit. METHODSANDRESULTS Seventy-four consecutive patients admitted for acute HF syndrome were analyzed. Blood tests and measurement of IVC diameter after stabilization of respiratory distress were performed on admission and were repeated after 24 h. IVC collapsibility index (IVC-CI) was calculated as (maximum IVC-minimum IVC)/maximum IVC. According to the initial IVC-CI, the patients were divided into the collapse group (IVC-CI ≥0.5: n=34) and the non-collapse group (IVC-CI <0.5: n=40). Initial blood pressure was higher in the collapse group (P<0.001). Although 24-h urine volume did not differ between the groups, hemoglobin (P<0.001) and hematocrit (P<0.001) decreased significantly in the collapse group but not in the non-collapse group after 24 h. Furthermore, IVC-CI significantly decreased in the collapse group after 24 h (P=0.003). CONCLUSIONS In acute HF syndrome, IVC-CI ≥0.5 on admission suggests a volume shift from the central vein into the pulmonary vasculature. Fluid refill occurs within 24 h after admission. This observation could be helpful in selecting strategies for diuretic use. (Circ J 2016; 80: 1171-1177).


The Journal of Clinical Endocrinology and Metabolism | 2003

Hypoadiponectinemia Is Closely Linked to Endothelial Dysfunction in Man

Michio Shimabukuro; Namio Higa; Tomohiro Asahi; Yoshito Oshiro; Nobuyuki Takasu; Tatsuya Tagawa; Shinichiro Ueda; Iichiro Shimomura; Tohru Funahashi; Yuji Matsuzawa


Endocrinology | 2007

Vascular Lipotoxicity: Endothelial Dysfunction via Fatty-Acid-Induced Reactive Oxygen Species Overproduction in Obese Zucker Diabetic Fatty Rats

Ichiro Chinen; Michio Shimabukuro; Ken Yamakawa; Namio Higa; Toshihiro Matsuzaki; Katsuhiko Noguchi; Shinichiro Ueda; Matao Sakanashi; Nobuyuki Takasu


The Journal of Clinical Endocrinology and Metabolism | 2006

Effects of a Single Administration of Acarbose on Postprandial Glucose Excursion and Endothelial Dysfunction in Type 2 Diabetic Patients: A Randomized Crossover Study

Michio Shimabukuro; Namio Higa; Ichiro Chinen; Ken Yamakawa; Nobuyuki Takasu


The American Journal of Clinical Nutrition | 2007

Effects of dietary composition on postprandial endothelial function and adiponectin concentrations in healthy humans: a crossover controlled study

Michio Shimabukuro; Ichiro Chinen; Namio Higa; Nobuyuki Takasu; Ken Yamakawa; Shinichiro Ueda

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Nobuyuki Takasu

University of the Ryukyus

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Ken Yamakawa

University of the Ryukyus

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Shinichiro Ueda

University of the Ryukyus

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Tomohiro Asahi

University of the Ryukyus

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Ichiro Chinen

University of the Ryukyus

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Yoshito Oshiro

University of the Ryukyus

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