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Naoto Nakamura

Publications and source records attributed to Naoto Nakamura.

At least 19 recordsLinked to original sources
PubMed2004

Enzyme-linked immunosorbent assay for circulating human resistin: resistin concentrations in normal subjects and patients with type 2 diabetes.

BACKGROUND: Resistin is a recently identified adipocyte-secreted hormone in rodents, and has been proposed to serve as a link between obesity and insulin resistance. The aim of this study was to develop a sensitive enzyme-linked immunosorbent assay (ELISA) for human resistin and evaluate serum resistin concentrations in normal subjects and patients with type 2 diabetes. METHODS: Using ELISA developed by two polyclonal antibodies, resistin concentrations were measured in 90 patients with type 2 diabetes and compared to 74 healthy control subjects. RESULTS: This ELISA has high specificity and sensitivity over the concentration of range 0.5-100 ng/ml with good percentage recovery (97.1 +/- 4.7%) and reproducibility (within-day assay, CV = 4.8-8.6%; between-day assay, CV = 5.6-9.7%). The mean concentration of resistin in sera from type 2 diabetic patients was significantly higher than that in normal subjects (mean +/- S.E.: 20.8 +/- 0.7 vs. 14.9 +/- 0.5 ng/ml, p < 0.001). A moderate positive correlation was observed between serum resistin levels and body mass indices in both normal subjects (r = 0.412, p < 0.0003) and patients with type 2 diabetes (r = 0.395, p < 0.0001). CONCLUSIONS: Our ELISA will be useful to confirm the physiological and pathophysiological role of resistin in humans.

Adipose Tissue↗
PubMed2003

Two expression vectors for the phage-displayed chicken monoclonal antibody.

We previously reported the development of chicken monoclonal antibodies (mAb) against mammalian-conserved molecules by cell fusion and phage display using the mouse mAb expression vector pPDS. However, chicken hybridomas produce relatively small amounts of antibody when compared with mouse hybridomas, and application of the pPDS may be limited in two-antibody assays with a mouse mAb because it contains mouse Ckappa as a detection tag. To circumvent the above problems, two expression vectors were established and used to produce a functional recombinant chicken mAb. These vectors, which were designed to accommodate a single chain fragment of the variable region (scFv) of the antibody, contained a chicken Clambda and FLAG with or without 6 x histidine sequences in the 3' terminus of the scFv to serve as detection and purification tags. In this study, a prion protein (PrP)-specific chicken mAb (HUC2-13) was expressed as phage-displayed and soluble scFv mAb forms by using these vectors. The scFv mAbs expressed by these vectors exhibited the same antigen-binding specificity to PrP as that of the original HUC2-13, could be purified with ease, and used in combination with a mouse mAb. These results indicate that the methods described herein offer an alternative to chicken mAb production from hybridomas and immunized chicken splenocytes, and may contribute to the use of chicken mAb reagents in numerous fields.

Animals↗
PubMed2003

Preliminary report of association of chronic diseases and erectile dysfunction in middle-aged men in Japan.

OBJECTIVES: To investigate the effect of chronic diseases on erectile dysfunction (ED) in Japanese middle-aged men using the International Index of Erectile Function, 5-item version (IIEF-5). METHODS: The subjects consisted of 640 healthy men and 396 men with chronic disease who responded to the IIEF-5 questionnaire (mean age 43.6 +/- 8.3 years, range 30 to 59). The incidence and severity of ED were calculated in three age groups (30 to 39, 40 to 49, and 50 to 59 years). RESULTS: The incidence of hypertension, cardiac disease, diabetes mellitus, and chronic renal failure was associated with the incidence and severity of ED, as was age. In stepwise multivariate logistic regression analysis, cardiac disease was the strongest independent risk factor (odds ratio [OR] 6.5), followed by diabetes mellitus (OR 5.9), chronic renal failure (OR 3.9), hypertension (OR 2.0), and age (OR 1.8). CONCLUSIONS: The results of this study demonstrated that the risk of ED increases with the presence of cardiac disease, diabetes mellitus, chronic renal failure, and hypertension in middle-aged men in Japan.

Adult↗
PubMed2003

Augmentation of central arterial pressure as a marker of atherosclerosis in patients with type 2 diabetes.

Macrovascular disease is the most common cause of morbidity and mortality in diabetic patients. With the increasing numbers of patients with type 2 diabetes, a simple, noninvasive method is needed to detect atherosclerosis. Augmentation represents the difference between the second and first peaks of the central arterial pressure waveform in systole and is a measure of systemic arterial stiffness, which causes the pressure wave to rebound. We investigated whether augmentation could serve as a marker of atherosclerosis in patients with type 2 diabetes. Central arterial pressure and degree of its augmentation by pulse wave rebound were measured sphygmographically in 208 consecutive patients with type 2 diabetes and 117 healthy control subjects. The relationship between augmentation and carotid atherosclerosis detected by carotid ultrasonography was investigated in a subgroup of 81 diabetic patients. Augmentation was greater in diabetic patients than control subjects (13.2+/-6.9 vs. 9.4+/-5.7 mm Hg, P<0.0001). The positive correlation between augmentation and intima-media thickness (r=0.309, P=0.0051) and between augmentation and plaque score (r=0.304, P=0.0059) were found in patients with type 2 diabetes. Augmentation was greater in diabetic patients with cardiovascular disease (n=47) than without (n=161; 15.1+/-8.4 vs. 12.6+/-6.3 mm Hg, P=0.031). Augmentation of central arterial pressure is a reliable marker for atherosclerosis in patients with type 2 diabetes. This simple, noninvasive determination would permit large-scale, early screening for atherosclerosis in patients with type 2 diabetes, who are at increased risk for cardiovascular disease.

Aged↗
PubMed2003

Increased concentration of pentosidine, an advanced glycation end product, and interleukin-6 in the vitreous of patients with proliferative diabetic retinopathy.

To investigate the relationship between advanced glycation end products (AGEs) and interleukin-6 (IL-6) in the development of diabetic retinopathy, we determined the concentrations of pentosidine, a well-characterized AGE, and IL-6 in the vitreous of 62 patients with proliferative diabetic retinopathy (PDR) and 50 non-diabetic control subjects. We also investigated the effect of AGEs on the production of IL-6 by human retinal Müller cells. The levels of pentosidine and IL-6 in the vitreous of patients with PDR were significantly higher compared with controls. In patients with PDR with vitreous hemorrhage (VH), the mean vitreous concentration of IL-6 was significantly higher than that in PDR patients without VH. There was a strong positive correlation between the vitreous levels of pentosidine and IL-6. Levels of IL-6 were strikingly higher in the vitreous compared with the serum and there was no correlation between IL-6 concentrations in the two fluids. Treatment of Müller cells with AGEs for 48 h resulted in a dose-dependent increase of IL-6 in the culture medium. These results suggest that increased formation of AGEs in the vitreous may be involved in the development of diabetic retinopathy by inducing the production of IL-6 from retinal Müller cells.

Adult↗
PubMed2003

TNF, TNF receptor type 1, and allograft inflammatory factor-1 gene polymorphisms in Japanese patients with type 1 diabetes.

The human leukocyte antigen (HLA) class III region, located on chromosome 6p21, has been regarded as one of the susceptible loci for type 1 diabetes. Because it contains many genes related to inflammatory and immune responses, including tumor necrosis factor (TNF), lymphotoxin-alpha (LT-alpha), and allograft inflammatory factor 1 (AIF-1) genes, it is unclear which gene within the class III region is responsible for the susceptibility to the disease. We sequenced the AIF-1 gene region and detected three novel polymorphisms, all of which were diallelic and localized at introns. Then, we investigated AIF-1, TNF, and LT-alpha gene polymorphisms in 165 patients with type 1 diabetes, consisting of 90 patients with young-onset type 1 diabetes, 75 patients with adult-onset type 1 diabetes, and 200 control patients. We also analyzed TNF receptors type 1 (TNFR1) and type 2 (TNFR2) gene polymorphisms, located on chromosome 12p13 and 1p36, respectively. Although there were significant differences between type 1 diabetes patients and controls in the distributions of TNF promoter polymorphisms at position -1031 and -857, and LT-alpha gene NcoI polymorphism, none of them was independently associated with the disease after two-locus analysis with HLA class II alleles. We detected the significantly increased frequency of the -383C allele, located in the TNFR-1 promoter region, in both young-onset and adult-onset diabetes patients compared with controls. In addition, the -383C allele was found to be associated with higher expression of the TNFR1 gene than that of -383A allele in in vitro expression. These results suggest that the TNFR1 gene region might be a susceptible locus to type 1 diabetes in Japanese.

Adult↗
PubMed2003

Different remodelling against left ventricular overload between diabetic and non-diabetic haemodialysis patients.

1. Diabetes mellitus is significantly associated with the occurrence of congestive heart failure in end-stage renal disease patients undergoing maintenance haemodialysis. In the present study, we asked whether the left ventricular remodelling against sustained pressure and/or volume overload to the left ventricle may be different between diabetic and non-diabetic haemodialysis patients. 2. Left ventricular parameters, including left ventricular mass index (LVMI), interventricular septal wall thickness (IVST) and relative left ventricular wall thickness (rLVWT), were assessed in 486 patients receiving maintenance haemodialysis (145 diabetic and 341 non-diabetic patients) using transthoracic echocardiography. Plasma concentrations of B-type natriuretic peptide (BNP), measured with an immunoradiometric assay, were used as a humoral parameter indicating left ventricular wall stress. 3. In non-diabetic patients, the plasma BNP concentration correlated with LVMI (r = 0.245; P = 0.0001), IVST (r = 0.250; P = 0.0001) and rLVWT (r = 0.149; P = 0.006). Furthermore, LVMI was correlated with mean blood pressure and pulse pressure and IVST and rLVWT were correlated with pulse pressure. 4. In contrast, none of the measured factors was correlated with LVMI and IVST in diabetic patients. Plasma BNP concentrations were positively correlated with end-systolic and end-diastolic left intraventricular dimensions and were inversely correlated with rLVWT and left ventricular fractional shortening in diabetic patients, but not in non-diabetic patients. 5. In conclusion, a sustained increase in left ventricular wall stress is likely to elicit eccentric left ventricular remodelling in diabetic haemodialysis patients, whereas it causes concentric left ventricular remodelling in non-diabetic haemodialysis patients. This difference in left ventricular remodelling against left ventricular overload may be associated with the high incidence of congestive heart failure in diabetic haemodialysis patients.

Aged↗
PubMed2003

Generation of antibodies against prion protein by scrapie-infected cell immunization of PrP(0/0) mice.

Four monoclonal antibodies (MAbs) specific for prion protein (PrP) were generated by using PrP-knockout mice immunized with a scrapie-infected mouse neuroblastoma cell line (N2a/22L). The MAbs reacted with both the cellular form (PrP(C)) and the protease K-treated form (PrP(Sc)) on Western blotting. Of the four MAbs, three recognized mouse and hamster PrP, while the remaining MAb recognized mouse, sheep, and bovine PrPs. In addition, these MAbs were shown to react only with the unglycosylated and monoglycoslated forms of PrP(Sc) in N2a/22L, but reacted with all glycosylated forms of PrP(C) and PrP(Sc) from mouse brain. This study was the first to report the development of anti-PrP MAbs using scrapie-infected cells as an immunogen and provides one approach for the generation of PrP-specific MAbs.

Animals↗
PubMed2003

The high incidence of left atrial appendage thrombosis in patients on maintenance haemodialysis.

BACKGROUND: The incidence of intracardiac thrombosis in haemodialysis patients has not been studied. Here we determined the incidence in end-stage renal disease patients on maintenance haemodialysis. METHODS: Transoesophageal echocardiography was performed in 215 patients (125 males, 90 females; mean age 60 +/- 9 years). Any potential candidate with current or past chronic or intermittent atrial fibrillation or with cardiovascular diseases was excluded from the study. RESULTS: Thrombi were found in the left atrial appendages in 71 out of 215 subjects (33%). Based on multiple logistic regression analyses, the probability of finding a thrombus was found to be increased in patients on chronic antiplatelet therapy (odds ratio 4.268) and in those with diabetes mellitus and a low haematocrit (</=0.3; odds ratio 7.173). Other clinical parameters, including gender, age, duration of haemodialysis, blood pressure, left ventricular dimension, smoking habit or type of anticoagulation during dialysis, were not associated with the incidence of left atrial appendage thrombosis. CONCLUSIONS: Maintenance haemodialysis patients have a high incidence of left atrial appendage thrombosis. Either chronic use of antiplatelet drugs or the background conditions requiring antiplatelet therapy, and the concomitant presence of diabetes mellitus and a low haematocrit may be involved in left atrial appendage thrombosis.

Aged↗
PubMed2003

In vivo functioning and transplantable mature pancreatic islet-like cell clusters differentiated from embryonic stem cell.

INTRODUCTION: Although the differentiation of embryonic stem (ES) cells to islet like clusters using differentiation method without employing gene transfer technique has been recently reported, neither endocrine granules in the cytoplasm nor in vivo function of differentiated islet like clusters has been demonstrated. AIMS: To investigate whether ES cells could be differentiated to mature islet like clusters which show in vivo function after transplantation as well as retain endocrine granules in the cytoplasm by electron microscopic observation. METHODOLOGY: In this experiment, using mouse embryonic stem (mES) cells as a model system for lineage specific differentiation, we tried to differentiate mES cells to pancreatic islet-like cell clusters (PICCs) through a series of treatments (4-step procedure). Differentiated PICCs were analyzed and characterized by various techniques, such as RT-PCR, immunohistochemistry, electron microscopic observation, in vitro static incubation test, and in vivo transplantation to diabetic animals. RESULTS: Differentiated islet-like cell clusters from ES cells using our newly developed method (four-step procedure) showed strong expression of essential specific genes to the endocrine pancreas and also specific genes to the exocrine pancreas demonstrating that these islet-like clusters were mature from the developmental biologic point of view. These differentiated cells clearly revealed many mature insulin secretory granules of pleomorphic shape in the cytoplasm as well as well-developed rough endoplasmic reticulum. In vitro study indicated that differentiated cells retain a potent insulin secretory responsiveness to glucose stimulation. Furthermore, the islet-like cell clusters significantly decreased high blood glucose levels almost to normal levels when grafted to streptozotocin-induced diabetic mice without induction of any teratoma formation after transplantation. CONCLUSION: Our results provide evidence that ES cells could differentiate to functioning and transplantable mature pancreatic islet-like cell clusters using our newly developed differentiation method without employing gene transfer technique. This study may lead to a basis for production of indefinite sources of islets that could be applicable for future clinical trial.

Animals↗
PubMed2003

Serum extracellular superoxide dismutase in patients with type 2 diabetes: relationship to the development of micro- and macrovascular complications.

OBJECTIVE: The aim of this study was to determine the distribution of serum extracellular superoxide dismutase (EC-SOD) concentrations in patients with type 2 diabetes and to assess whether increased EC-SOD concentration is associated with the development of diabetic vascular complications. RESEARCH DESIGN AND METHODS: Serum EC-SOD concentrations were determined in 222 patients with type 2 diabetes and 75 healthy control subjects by an enzyme-linked immunosorbent assay. All subjects had the EC-SOD domain genotyped. RESULTS: The serum EC-SOD concentrations showed a distinct bimodal distribution in both patients with diabetes and control subjects. All subjects with the high-level phenotype carried the Arg213Gly mutation. The frequency of this variant was similar in the diabetes and control groups. Within the group of subjects with the common EC-SOD phenotype, the serum EC-SOD concentration (mean +/- SE) was significantly higher in patients with type 2 diabetes (99.3 +/- 1.3 ng/ml) compared with the control subjects (68.4 +/- 2.3 ng/ml, P < 0.01). Stepwise multiple regression analysis of the data from the diabetic common phenotype group showed a significant relationship between serum EC-SOD concentration and duration of diabetes (F = 5.31), carotid artery intimal-media thickness (F = 8.24), and severity of nephropathy (F = 16.05) and retinopathy (F = 4.43). CONCLUSIONS: We observed a strong relationship between the serum concentration of EC-SOD and the severity of both micro- and macrovascular diabetic complications. These findings suggest that serum EC-SOD concentration levels may be a marker of vascular injury, possibly reflecting hyperglycemia-induced oxidative injury to the vascular endothelium and decreased binding of EC-SOD to the vascular wall.

Amino Acid Substitution↗
PubMed2003

Association between serum testosterone concentration and carotid atherosclerosis in men with type 2 diabetes.

OBJECTIVE: There is evidence to suggest that low concentrations of testosterone are associated with an increased risk of cardiovascular disease in men. The aim of this study was to evaluate the relationship between serum testosterone concentration and carotid atherosclerosis as well as major cardiovascular risk factors in men with type 2 diabetes. RESEARCH DESIGN AND METHODS: Serum free and total testosterone concentrations were measured in 253 consecutive men with type 2 diabetes. The relationships between serum testosterone concentration and carotid atherosclerosis, determined by ultrasonographically evaluated intima-media thickness (IMT) and plaque score (PS) in a subgroup of 154 diabetic patients, as well as major cardiovascular risk factors, including age, blood pressure, and lipid concentrations, were evaluated. RESULTS: Inverse correlations were found between free testosterone (F-tes) concentration and IMT (r = -0.206, P = 0.0103) and between F-tes concentration and PS (r = -0.334, P < 0.001). The IMT and PS were significantly greater in patients with lower concentrations of F-tes (<10 pg/ml) than in patients with higher concentrations of F-tes (1.01 +/- 0.29 vs. 0.91 +/- 0.26 mm, P = 0.038; 4.5 +/- 3.8 vs. 2.4 +/- 3.2, P = 0.0003; respectively). An inverse correlation was found between serum F-tes concentration and age (r = -0.420, P < 0.0001). A positive correlation was found between serum F-tes and total cholesterol concentrations (r = 0.145, P = 0.0238). CONCLUSIONS: Serum F-tes concentration is inversely associated with carotid atherosclerosis determined by ultrasonographically evaluated IMT and PS in men with type 2 diabetes.

Age of Onset↗
PubMed2002

Polymorphisms of interferon-gamma gene CA-repeat and interleukin-10 promoter region (-592A/C) in Japanese type I diabetes.

We investigated the association of the polymorphisms of interferon-gamma gene (IFNG) CA-repeat and IL-10-592A/C with clinical heterogeneity of type I diabetes as well as susceptibility to type I diabetes. Two hundred seven Japanese type I diabetic patients and 160 healthy control subjects were studied in this case-control study. No significant differences of global IFNG allele frequencies were found between controls and type I diabetic patients, and between each subgroup of the patients and controls. When compared with controls, the a12 allele was increased in the patients with age at onset <25 years (p 0.0241, p(c) = 0.1205), and a significant increased frequency of the a12 positive genotype was observed in the patients with age at onset <25 years (p(c) = 0.0121). There were no differences of IL-10-592 genotype and allele frequencies between controls and type I diabetes. However, the frequency of the -592*C allele was significantly increased in the patients with highly positive-GADab compared with controls (p(c) = 0.0060) or compared with the GADab-negative type I patients (p(c) = 0.0276). These results suggest that the IFNG CA-repeat and the IL-10-592A/C polymorphisms are not strong determinants of susceptibility to the development of type I diabetes in Japanese individuals. However, both the IFNG CA-repeat and the IL-10-592A/C polymorphisms are associated with clinical heterogeneity in type I diabetes.

Adult↗
PubMed2002

Association of HLA class I and class II alleles with susceptibility to endometriosis.

Although the exact etiology of endometriosis is unclear, several lines of evidence support roles for both cell-mediated and humoral immunity in its pathogenesis. To assess the association between HLA genotypes and endometriosis, we investigated the frequencies of HLA-A, -B, -C, and -DRB1 antigens or alleles in 123 Japanese patients with endometriosis and 165 healthy women as controls. Significant positive association with endometriosis was observed for HLA-B7 (OR = 2.7, 95% CI = 1.5-5.1, p(u) = 0.0022, p(c) = 0.0440) and for Cw*0702 (OR = 2.1, 95% CI = 1.2-3.3, p(u) = 0.0026, p(c) = 0.0398). An increased frequency of DRB1*0101 was observed in endometriosis patients compared with control subjects (OR = 2.3, 95% CI = 1.2-4.4, p(u) = 0.0143), but was not statistically significant after correction for multiple comparisons. Two-locus analysis indicated that the susceptibility to endometriosis was primarily associated with B7, and that the increased frequencies of Cw*0702 and DRB1*0101 in patients reflected the linkage disequilibrium between B7 and Cw*0702 and DRB1*0101. Most of the B7 antigens were encoded by the B*0702 allele, which was in complete linkage disequilibrium with A24, Cw*0702, and DRB1*0101. Therefore, our results indicated that the HLA-A24-B*0702-Cw*0702-DRB1*0101 haplotype was associated with endometriosis susceptibility. Our findings may provide an important clue to elucidating the pathogenesis of endometriosis.

Adult↗