Kazunori Koyama

International University of Health and Welfare, Otahara, Tochigi, Japan

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Publications (5)16.61 Total impact

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    ABSTRACT: Serum amyloid A low-density lipoprotein (SAA-LDL) is formed by an oxidative interaction and is considered to be a new marker related to oxidative modification of LDL. As the effect of smoking on oxidized LDL is of concern, this study investigated the association between SAA-LDL and smoking status. A total of 578 Japanese obese outpatients (mean ± SD age 50.5 ± 14.3 years) were studied. Smoking status was examined via a self-reported questionnaire. Cardio metabolic variables, including high-sensitivity Creactive protein (hsCRP), were analysed in addition to SAA-LDL. There was an increasing trend in SAA-LDL levels from non- to ex- to current smokers, and significantly higher SAA-LDL levels were observed in current smokers versus non-smokers (median SAA-LDL level 36 μg/ml versus 28 μg/ml, respectively). This significant difference was reduced after adjusting for multiple confounders, including lipid levels. Smoking may be associated with increased levels of SAA-LDL in an obese Japanese population, but further studies are needed.
    Full-text · Article · Oct 2011 · The Journal of international medical research
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    ABSTRACT: Although the circulating levels of remnant-like particle cholesterol (RLP-C) or serum amyloid A-low-density lipoprotein (SAA-LDL) can individually be increased in subjects with metabolic syndrome (MetS), the correlation between the two markers has not yet been previously studied. In the present study, we aimed to investigate the correlation between RLP-C and SAA-LDL in obese subjects with MetS in comparison to those without MetS. A total of 436 obese subjects were divided into groups with MetS and without MetS (male/female 75/143, mean age 49 years, current smokers 16% in both groups) by applying the age-, gender-, and smoking habit-matching method based on the database in the multicenter Japan Obesity and Metabolic Syndrome Study (JOMS). The data, including RLP-C and SAA-LDL, were compared in each group. Significantly greater levels of RLP-C or SAA-LDL were observed in subjects with MetS in comparison with those without MetS. There was a significantly positive correlation between RLP-C and SAA-LDL, with a relatively greater correlation in subjects with MetS (coefficient = 0.290, P < .01) in comparison with those without MetS (coefficient = 0.181, P < .01). Multivariate-adjusted correlation analyses showed a greater correlation between RLP-C and SAA-LDL in subjects with MetS, relative to those without MetS, although the significant correlation decreased in both groups when the hypertriglyceridemic states were taken into account. A relatively greater and positive correlation between greater levels of RLP-C and SAA-LDL in obese subjects with MetS, in comparison with those without MetS, may be linked to the development of MetS-related cardiovascular disease.
    No preview · Article · Sep 2011 · Journal of Clinical Lipidology
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    ABSTRACT: Obesity and metabolic syndrome (MS) increase the risk of cardiovascular disease (CVD), chronic kidney disease (CKD), and all-cause mortality. Serum cystatin C (S-CysC), a marker of GFR, has been shown to be associated with CVD and CKD. This study was designed to elucidate the association of urinary CysC (U-CysC), a marker of renal tubular dysfunction, with CVD and CKD risk factors in patients with obesity and MS. The U-CysC-creatinine ratio (UCCR) was examined in 343 Japanese obese outpatients enrolled in the multi-centered Japan Obesity and Metabolic Syndrome Study. UCCR was positively correlated with urine albumin-creatinine ratio (UACR) and S-CysC and negatively correlated with estimated GFR (eGFR). Among obese patients, UCCR was significantly higher in MS patients than in non-MS patients. UCCR had significant correlations with the number of components of MS and arterial stiffness, all of which are CVD predictors, similarly to UACR (P<0.05). Interestingly, diet- and exercise-induced weight reduction for 3 months significantly decreased only UCCR among all of the renal markers examined (P<0.01), in parallel with the decrease in BMI, HbA1c, and arterial stiffness, suggesting the beneficial effect of weight reduction on renal tubular dysfunction. This study demonstrates that UCCR is significantly associated with renal dysfunction, the severity of MS, arterial stiffness, and weight change in obese patients. The data of this study suggest that U-CysC could serve as a CVD and CKD risk factor in patients with obesity and MS.
    Preview · Article · Nov 2010 · Clinical Journal of the American Society of Nephrology
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    ABSTRACT: Aortic stiffness is predictive of cardiovascular diseases (CVD) and mortality in lifestyle-related diseases. The cardio-ankle vascular index (CAVI), a new index of arterial stiffness, was recently developed by measuring of pulse wave velocity (PWV) and blood pressure (BP). CAVI is adjusted for BP based on stiffness parameter beta and is less influenced by BP, suggesting its superiority over brachial-ankle PWV (baPWV). However, there are currently no reports on the usefulness of CAVI as an atherogenic index in obesity and metabolic syndrome (MS). Among the 325 obese Japanese outpatients enrolled in the multi-centered Japan Obesity and Metabolic Syndrome Study, 216 patients (67%) met the criteria of MS according to the modified National Cholesterol Education Program-Adult Treatment Panel III. CAVI values were significantly higher in MS than in non-MS patients, whereas there was no significant difference in body mass index, total cholesterol, and low-density lipoprotein-cholesterol between both groups. CAVI values were weakly correlated with BP but closely correlated with the severity of MS and MS-related parameters such as hypoadiponectinemia, relative to baPWV. Furthermore, weight-reduction therapy through diet and exercise over a 3-month period significantly decreased CAVI values in parallel with increasing adiponectin. This study demonstrates for the first time that CAVI is a good indicator of arterial stiffness. It is closely correlated with the severity of MS and CVD risks in obesity and independent of BP, and is thus superior to baPWV. Therefore, the determination of arterial stiffness by CAVI may be useful for evaluating and managing the CVD risks of MS patients.
    Full-text · Article · Nov 2008 · Hypertension Research
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    ABSTRACT: The putative association between the novel oxidized low-density lipoprotein markers, serum amyloid A-LDL (SAA-LDL) and alpha1-antitrypsin-LDL (AT-LDL), and obesity and the metabolic syndrome (MetS) has not been previously studied. In the present report, we investigated the levels of SAA-LDL and AT-LDL in relation to the components of the MetS. We also assessed the effect of weight reduction therapy on serum SAA-LDL and AT-LDL levels among obese subjects. The study population included 421 obese Japanese outpatients (185 men and 236 women, mean age: 51.1 years) enrolled in the multicenter Japan Obesity and Metabolic Syndrome Study (JOMS). The novel oxidized low-density lipoprotein markers, serum SAA-LDL and AT-LDL, were measured in all participants. Circulating SAA-LDL levels were independently associated with the presence and the number of components of the MetS. SAA-LDL levels were also significantly and independently correlated with high-sensitivity C-reactive protein. Notably, successful weight reduction resulted in a significant decrease in circulating SAA-LDL concentrations. Levels of AT-LDL were not associated with the MetS. We documented, for the first time, that serum SAA-LDL levels correlate positively with the number of components of the MetS and weight reduction. Whether SAA-LDL may be involved in the pathophysiology of MetS and atherosclerosis deserves further investigation.
    No preview · Article · Oct 2008 · Atherosclerosis

Publication Stats

104 Citations
16.61 Total Impact Points


  • 2008-2011
    • International University of Health and Welfare
      Otahara, Tochigi, Japan
    • Nho Tokyo Medical Center
      Edo, Tōkyō, Japan
  • 2010
    • Niigata University of Health and Welfare
      Niahi-niigata, Niigata, Japan