Circulating extracellular vesicles are associated with lipid and insulin metabolism.

We have reported that hypertrophic adipocytes release extracellular vesicles (EVs) and the number of circulating adipocyte-derived EVs correlated with insulin and homeostasis model assessment-insulin resistance (HOMA-IR) in a pilot study using obese patients. Here, we explored the association between circulating EV level and various metabolic parameters, including obesity and lipid and glucose metabolisms, among 203 subjects (76 men and 127 women; median age, 54 yr) with or without risk factor for metabolic diseases, who received a 75-g oral glucose tolerance test (OGTT). Circulating EV number was significantly higher in men than in women ( P < 0.001). Circulating EV number in individuals with impaired OGTT pattern was significantly higher compared with those with normal OGTT patterns ( P < 0.05). Multiple regression analysis revealed that circulating EV number correlated most strongly and significantly with elevated triglyceride (TG; t = 8.55, P < 0.001). Additionally, circulating EV number correlated significantly with homeostasis model assessment-ß-cell function (HOMA-ß; t = 2.38, P < 0.05). Receiver operating characteristic curve revealed that the cutoff value of EV numbers in individuals with elevated serum TG levels (≧150 mg/dl) was identified (136,738 EVs/µl of plasma, P < 0.001, sensitivity 0.842, false-positive rate of 0.257). Perilipin and asialoglycoprotein receptor 1 were detected on a part of isolated circulating EVs, indicating EV release from adipocytes and hepatocytes, which were related to lipid and glucose metabolism. Circulating EVs represent a promising metabolic biomarker for lipid and glucose metabolism and have potential for monitoring metabolic status in humans, including individuals without metabolic risk factors.

Impact of renal function on the underlying pathophysiology of coronary plaque composition in patients with type 2 diabetes mellitus.

BACKGROUND: Both the progression of diabetic kidney disease and increased glycemic variability play important roles in the pathogenesis of coronary plaque formation via inflammatory pathways in patients with type 2 diabetes mellitus (T2DM). Therefore we evaluated the role of renal function in the contributory effects of blood glucose fluctuations and blood levels of inflammatory cytokine concentrations on the tissue characteristics of coronary plaques in patients with T2DM. METHODS: We prospectively enrolled 71 T2DM patients (mean age: 68 ± 9, male 79%) with 153 coronary artery lesions. Patients were divided into 2 groups according to their estimated glomerular filtration rate (eGFR) levels: Group 1 (≥ 60 mL/min/1.73 m2, n = 40) and Group 2 (< 60 mL/min/1.73 m2, n = 31). All patients underwent continuous glucose monitoring (CGM) for 120 h and the mean amplitude of glycemic excursions (MAGE) was calculated. Serum tumor necrosis factor (TNF)-α was also measured. In addition, gray-scale coronary intravascular ultrasound (IVUS) and iMap-IVUS were performed in the coronary lesions with < 50% luminal reduction. RESULTS: In Group 1, MAGE correlated with percent lipidic volume (%LV) (r = 0.477, p = 0.002). In this group, stepwise multivariate linear regression analyses showed that only MAGE was independently associated with %LV (ß = 0.477, p = 0.002). In contrast, in Group 2, only serum TNF-α correlated with percent fibrotic volume (%FV) (r = - 0.471, p = 0.007), %LV (r = 0.496, p = 0.005) and percent necrotic volume (%NV) (r = 0.426, p = 0.017). In this group, stepwise multivariate linear regression analyses showed that only serum TNF-α was independently associated with each tissue characteristic (%FV ß = - 0.471 and p = 0.007, %LV ß = 0.496 and p = 0.005, %NV: ß = 0.426 and p = 0.017). CONCLUSIONS: In T2DM patients, the tissue characteristics of coronary plaques were associated with MAGE in patients with eGFR ≥ 60 mL/min/1.73 m2 and with serum TNF-α in those with eGFR < 60 mL/min/1.73 m2.

Presence of thrombin-activatable fibrinolysis inhibitor in Helicobacter pylori-associated gastroduodenal disease.

Thrombin-activatable fibrinolysis inhibitor (TAFI) plays a role in the regulation of coagulation and inflammation. In addition to inhibiting the fibrinolytic system, TAFI may also regulate the bradykinin and complement systems. We hypothesized that TAFI also plays a role in defense mechanisms of the gastric mucosa during Helicobacter pylori infection. This study comprised 65 patients with gastroduodenal disorders: 41 patients with H. pylori infection, 13 without, and 11 patients with cured H. pylori infection. The gastric intramucosal concentrations of TAFI were measured by enzyme immunoassay. The gastric levels of TAFI and plasminogen activator inhibitor-1 were significantly increased in patients with H. pylori compared to those without infection or cured H. pylori. The presence of TAFI was detected in gastric mucosal epithelial cells. The concentration of TAFI was correlated with the degree of gastric mucosal atrophy, inflammation, and disease activity. These results show that TAFI is present in the gastric mucosa and that it may play a role in the pathogenesis of H. pylori infection-associated gastroduodenal disorders.

Role of the coagulation system in allergic inflammation in the upper airways.

Thrombin has been detected and demonstrated to play a role in the airways of patients with bronchial asthma, but its role in the upper airways including during allergic rhinitis is unknown. This study was conducted to explore whether thrombin is presence in the upper airways and, if so, whether it affects mucin secretion. Fifteen patients with allergic rhinitis were enrolled in the clinical study; primary nasal septum epithelial cells and normal bronchial epithelial cells were used for in vitro evaluation, and rats as animal models. Significant concentrations of thrombin were found in nasal secretion after allergic provocation in allergic patients, and thrombin and its agonistic receptor peptide induced significant secretion of mucin in primary nasal cells and normal bronchial epithelial cells as compared to non-stimulated cells. Increased mucosubstance secretion in septum epithelial cells was also induced after nasal instillation of thrombin in rats. Further, the anticoagulant, activated protein C, significantly inhibited thrombin-induced mucin secretion from septum epithelial cells in rats. The results of this study suggest that activation of the coagulation system occurs during the allergic response and that thrombin plays a crucial role in the regulation of mucin production in the upper airways.

The tetraspanin CD151 regulates cell morphology and intracellular signaling on laminin-511.

The tetraspanin CD151 forms a stable complex with integrin alpha3beta1, a widely expressed laminin receptor, and is implicated in the regulation of integrin alpha3beta1-mediated cellular responses, including cell attachment, spreading and migration. However, the molecular mechanism by which CD151 regulates integrin alpha3beta1 functions remains unclear. To address this issue, we knocked down CD151 expression in A549 human lung adenocarcinoma cells by RNA interference. When plated on laminin-511 (laminin-10), the CD151-knocked-down cells showed aberrant membrane protrusions and exhibited reductions in the tyrosine phosphorylation of focal adhesion kinase, Src, p130Cas and paxillin. The formation of membrane protrusions was attenuated when the cells were either plated on surfaces coated with higher concentrations of laminin-511 or treated with the integrin beta1-activating mAb TS2/16; however, neither treatment could rescue the reduced tyrosine phosphorylation. These results indicate that CD151 knockdown weakens the integrin alpha3beta1-mediated adhesion to laminin-511 and thereby provokes an aberrant morphology, but this reduced adhesive activity is not involved in the decline of signaling events in CD151-knocked-down cells. Thus, our results suggest that CD151 regulates integrin alpha3beta1 functions in two independent aspects: potentiation of integrin alpha3beta1-mediated cell adhesion and promotion of integrin alpha3beta1-stimulated signaling events involving tyrosine phosphorylation.

Immune complex-mediated glomerulonephritis is ameliorated by thrombin-activatable fibrinolysis inhibitor deficiency.

The activity of plasmin plays a critical role in the development of chronic glomerulonephritis. Thrombin-activatable fibrinolysis inhibitor (TAFI) is a potent inhibitor of plasmin generation. We hypothesized that TAFI is involved in the pathogenesis of glomerulonephritis because it inhibits plasmin generation. To demonstrate this hypothesis, we compared the development of immune complex-mediated glomerulonephritis in wild-type and TAFI-deficient mice. After six weeks of treatment with horse spleen apoferritin and lipoplysaccharide to induce glomerulonephritis, mice deficient in TAFI had significantly better renal function as shown by lower concentrations of albumin in urine and blood urea nitrogen compared to wild-type mice. In addition, the activity of plasmin and matrix metalloproteinases was significantly increased, and mesangial matrix expansion and the deposition of collagen and fibrin in kidney tissues were significantly decreased in TAFI-knockout mice as compared to their wild-type counterparts. Depletion of fibrinogen by batroxobin (Defibrase) treatment led to equalization of the renal function and the amount of collagen deposition in the kidneys of TAFI-knockout and wild-type mice with immune complex-mediated glomerulonephritis. Together these observations suggest that TAFI-mediated inhibition of plasmin generation plays a role in the pathogenesis of glomerulonephritis, and that it may constitute a novel molecular target for the therapy of this disease.

Inhibition of nuclear factor-kappaB in T cells suppresses lung fibrosis.

RATIONALE: Cytokines secreted by T cells play a pivotal role in the pathogenesis of lung injury and fibrosis, and the transcription factors nuclear factor (NF)-kappaB and activator protein (AP)-1 are involved in the expression of cytokines from T cells during lung injury. OBJECTIVES: We assessed the potential therapeutic effect of SP100030, a specific inhibitor of T-cell NF-kappaB and AP-1 in lung fibrosis. METHODS: The effect of SP100030 was evaluated using a mouse model of chronic lung fibrosis. MEASUREMENTS AND MAIN RESULTS: Mice treated with SP100030, as compared with untreated mice, had significantly less cachexia and less lung injury and had decreased levels of inflammatory cytokines and growth factors, decreased activation of coagulation activation, and decreased collagen deposition in the lung. The inhibitory activity of SP100030 was dose dependent and was effective in acute and chronic phases of lung fibrosis. SP100030 inhibited the activation of the protein kinase C-isoform in T-cell lines and suppressed NF-kappaB-driven cytokine expression in CD4(+) and CD8(+) T cells. CONCLUSIONS: These results suggest that the specific inhibition of NF-kappaB could be useful for the treatment of lung fibrosis.

Monocyte chemoattractant protein-1 promoter -2518 polymorphism is associated with post-challenge insulin and glucose levels in non-diabetic Japanese subjects.

We investigated that the association of MCP-1 polymorphism at position -2518 with insulin sensitivity and insulin secretion by measuring the fasting and post-challenge glucose and insulin levels during 75g OGTT in 409 non-diabetic Japanese subjects. The blood sampling was performed before glucose loading and after 30 and 120 min. Polymorphism was evaluated by PCR-RFLP method by genomic DNA isolated from peripheral blood leukocytes. The genotype distribution was 44.8% for G/G, 46.0% for G/A and 9.2% for A/A. The plasma glucose levels were significantly increased in A/A as compared to G/G (p<0.05), but it was not compared with G/A at 120 min. The serum insulin levels were significantly increased in A/A as compared to G/A (p<0.05) or G/G (p<0.05) at 30 min. Moreover, the serum insulin levels in A/A were significantly increased compared with G/A (p<0.02) or G/G (p<0.005) at 120 min. Elevation in post-challenge glucose (120 min) and insulin levels (30 and 120 min) suggests that reduced insulin sensitivity during glucose loading occurs in subjects with A/A polymorphism. The present study demonstrates that the A/A polymorphism of the MCP-1 gene at position -2518 is associated with insulin resistance during glucose loading in non-diabetic Japanese subjects.

Increased oxidative stress is associated with decreased circulating levels of adiponectin in Japanese metabolically obese, normal-weight men with normal glucose tolerance.

To investigate the relationship between oxidative stress and circulating levels of adiponectin in Japanese metabolically obese, normal-weight [MONW; BMI<25 and visceral fat area; VFA > or =100 cm2 by abdominal computed tomography (CT) scanning] men with normal glucose tolerance (NGT), we measured the plasma levels of free 8-epi-prostaglandin F2alpha (8-epi-PGF2alpha) and adiponectin in 28 MONW and 23 normal men. The plasma levels of free 8-epi-PGF2alpha were measured using a commercially available enzyme immunoassay (EIA) kit (Cayman Chemical, Ann Arbor, MI). The plasma levels of adiponectin were measured using a radioimmunoassay kit (LINCO Research, St. Charles, MO). Plasma levels of 8-epi-PGF2alpha in MONW subjects (30.4+/-4.0 pg/ml; P<0.01) were significantly increased compared to controls (8.1+/-1.3 pg/ml). The plasma levels of adiponectin were significantly decreased in MONW subjects (8.6+/-0.9 microg/ml; P<0.01) as compared to normal subjects (11.6+/-0.6 microg/ml). The plasma levels of 8-epi-PGF2alpha and adiponectin were significantly correlated in MONW (r=-0.617, P<0.01) and in all (MONW+normal) (r=-0.620, P<0.01) subjects. The plasma levels of 8-epi-PGF2alpha and adiponectin were significantly correlated after adjustment for VFA in MONW subjects (F=11.042, P<0.01). The present study showed that systemic increase in oxidative stress correlates with decreased circulating levels of adiponectin in Japanese MONW men with NGT. Although correlation does not prove causation, this observation suggests that increased oxidative stress may decrease the production of adiponectin in Japanese MONW men with NGT.

Different metabolic correlations of thrombin-activatable fibrinolysis inhibitor and plasminogen activator inhibitor-1 in non-obese type 2 diabetic patients.

We investigated the plasma levels of thrombin-activatable fibrinolysis inhibitor (TAFI), plasminogen activator inhibitor-1 (PAI-1) and their relation with clinical and metabolic parameters in non-obese type 2 diabetic patients. The plasma levels of TAFI and PAI-1 were evaluated in 47 non-obese type 2 diabetic patients and 31 normal subjects. The intra-abdominal visceral and subcutaneous fat areas were measured by computed tomography (CT). The degree of insulin resistance was evaluated by the euglycemic-hyperinsulinemic clamp technique using artificial pancreas. The plasma levels of TAFI (169.0+/-108.8% versus 103.7+/-52.3%; p<0.001, mean+/-S.D.) and PAI-1 (82.7+/-54.5ng/ml versus 52.9+/-51.7ng/ml; p<0.05) were significantly higher in non-obese type 2 diabetic patients than in normal subjects. Univariate analysis showed that the plasma TAFI levels are significantly and inversely correlated with the glucose infusion rate (GIR) (r=-0.42, p<0.005) in all diabetic patients. Moreover, the plasma levels of TAFI were significantly correlated with fasting plasma glucose levels (r=0.47, p<0.001) and HbA(1c) (r=0.38, p<0.005) in all subjects. The plasma levels of PAI-1 were significantly and proportionally correlated with the visceral fat area (r=0.42, p<0.005) and body mass index (r=0.33, p<0.05). There was no significant correlation between plasma levels of TAFI and PAI-1 (r=0.04). These results show that the plasma levels of TAFI and PAI-1 differently correlate with insulin resistance and visceral fat accumulation, suggesting that different factors are implicated in the plasma elevation of TAFI and PAI-1 in non-obese type 2 diabetes mellitus.

Associations among circulating branched-chain amino acids and tyrosine with muscle volume and glucose metabolism in individuals without diabetes.

OBJECTIVES: Amino acid metabolites, including branched-chain amino acids (BCAA) and tyrosine (Tyr), affect glucose metabolism. The effects of BCAA on insulin resistance in patients with diabetes seem to conflict with mechanisms determined in animal models and cultured cells. The aim of this study was to clarify the controversy surrounding the effects of BCAA by investigating the physiological effects of BCAA and Tyr on glucose metabolism in healthy community dwellers. METHODS: We investigated associations among BCAA and Tyr and metabolic parameters in 78 residents (median age, 52 y) of Mie, Japan, who did not have prediabetes, diabetes, or a body mass index >30 kg/m(2). RESULTS: Muscle volume, serum BCAA, and Tyr levels were higher in men than in women (n = 32 and 46, respectively; all P < 0.0001). Stepwise multiple regression analysis associated BCAA positively with muscle volume (regression coefficient/t/p/95% confidence interval, 281.8/3.7/0.0004/129.7-433.8), fasting blood glucose (FBG; 12699.4/3.22/0.0020/4830.9-20567.8), fasting immunoreactive insulin (IRI; 8505.1/2.75/0.0078/2322.5-14687.6), and homeostasis model assessment of ß-cell function (HOMA-ß; 893.6/2.58/0.0122/201.8-1585.5), and negatively with the HOMA-insulin resistance (HOMA-IR; -9294.1/-2.89/0.0052/-15711.0 to -2877.1). Tyr positively correlated with fasting IRI (26/2.77/0.0072/7.3-44.7). CONCLUSIONS: Insulin sensitivity and muscle volume are positively associated with BCAA in individuals without diabetes. In turn, BCAA correlate with increased FBG and fasting IRI levels. Tyr correlated with fasting IRI, but not with insulin sensitivity.

Association of Waist Circumference and Body Fat Weight with Insulin Resistance in Male Subjects with Normal Body Mass Index and Normal Glucose Tolerance.

Objective We investigated the relationship of the waist circumference (WC) and body fat weight (BF) with insulin resistance in subjects with normal body mass index (BMI) and normal glucose tolerance (NGT) during a routine medical check-up. Methods We categorized 167 male subjects in three groups as follows: a group with normal BMI but high WC (normal-BMI/high-WC group; 22≤BMI<25 kg/m(2), waist ≥85 cm; n=31), a group with normal BMI and normal WC (normal-BMI/normal-WC group, waist <85 cm; n=68), and a group with low normal BMI and normal WC (low normal-BMI/normal-WC group; 18.5≤BMI<22 kg/m(2) and waist<85 cm; n=68). We measured the plasma glucose and serum insulin levels before glucose loading and after 30 and 120 minutes and calculated several indexes of insulin secretion and sensitivity. Results Subjects from the normal-BMI/high-WC group showed significantly decreased Matsuda index and increased homeostasis model assessment for insulin resistance (HOMA-IR) compared with normal-BMI/normal-WC group. Univariate regression analyses showed significant correlation of HOMA-IR with WC (r=0.39) and BF (r=0.37). Matsuda index was significantly correlated with WC (r=-0.39) and BF (r=-0.47). The multiple regression analysis showed that the BF is significantly correlated with HOMA-IR (p<0.05) and Masuda index (p<0.005) among the clinical variables and with HOMA-IR (p<0.05) and Masuda index (p<0.0001) among the anthropometric variables but not with WC in either analysis. Conclusion Decreased Matsuda index and increased HOMA-IR were observed in subjects from the normal-BMI/high-WC group. Multivariate analysis showed that BF is associated with decreased Matsuda index and increased HOMA-IR and that WC is not associated with either factors.

Decreased circulating levels of active ghrelin are associated with increased oxidative stress in obese subjects.

OBJECTIVE: To investigate the relationship between active ghrelin and oxidative stress in obese subjects. DESIGN: We measured the plasma levels of free 8-epi-prostaglandin F(2alpha) (8-epi-PGF(2alpha), a reliable and systemic marker of oxidative stress) and the active form of ghrelin in 17 obese and 17 normal subjects. The biologically active forms of ghrelin were measured using a commercially available radio-immunoassay kit and free 8-epi-PGF(2alpha) was measured using an enzyme immunoassay kit. RESULTS: The circulating level of active ghrelin was significantly decreased (20.4 +/- 2.6 vs 40.9 +/- 3.9 fmol/ml, P < 0.01) while that of 8-epi-PGF(2alpha) was significantly increased (61.5 +/- 9.6 vs 17.3 +/- 3.4 pg/ml, P < 0.01) in obese subjects compared with normal subjects. The plasma levels of active ghrelin and 8-epi-PGF(2alpha) were significantly correlated in obese (r = -0.507, P < 0.05) and in all (r = -0.577, P < 0.01) subjects. Multivariate analysis showed that the plasma levels of active ghrelin and 8-epi-PGF(2alpha) were significantly and independently correlated in all subjects (F = 7.888, P < 0.01). CONCLUSIONS: There is an inverse correlation between circulating levels of active ghrelin and oxidative stress in obesity. Low circulating levels of active ghrelin may enhance oxidative stress and the process of atherosclerosis in obese subjects.

C-514T polymorphism in hepatic lipase gene promoter is associated with elevated triglyceride levels and decreasing insulin sensitivity in nondiabetic Japanese subjects.

Hepatic lipase (HL) is synthesized in the liver and hydrolyses triglyceride and phospholipids. C-514T polymorphism in HL gene promoter was reported to associate with hepatic lipase activity and plasma lipid levels. We examined whether C-514T polymorphism affects glucose metabolism beyond its effect on plasma lipid levels in nondiabetic Japanese subjects. Gene frequencies of C/C homozygote, C/T heterozygote and T/T homozygote were 18, 51 and 31%, respectively. The allelic frequencies of C and T were 44 and 56%, respectively. T allele frequency was much higher than in Caucasian subjects. Moreover, -514T allele carriers had higher levels of triglyceride (P=0.027), fasting insulin (P=0.016) and HOMA-IR (P=0.033) than non-carriers. In contrast to some former studies, -514T allele affected triglyceride levels and insulin sensitivity. Taken together, HL gene might be one of the important susceptibility genes of type 2 diabetes and the high incidence of type 2 diabetes could be explained by high frequency of -514T allele in the Japanese population. Moreover, since HL and adiponectin showed an additive effect on insulin sensitivity, these genetic variations can be independently associated with insulin sensitivity.

Insulin enhanced thrombin-activable fibrinolysis inhibitor expression through PI3 kinase/Akt pathway.

Thrombin-activable fibrinolysis inhibitor (TAFI) is a key modulator of fibrinolysis. We have reported the elevated levels of plasma TAFI and their correlation with visceral fat area and insulin resistance in the patients with type 2 diabetes. Furthermore, the expression of TAFI was demonstrated in adipose tissues. Thus, we hypothesized that TAFI secreted from adipose tissues might be an important causative factor of hypofibrinolysis in patients with insulin resistance and that insulin was a modulator of the gene expression of TAFI. To evaluate this hypothesis, we examined the regulation of TAFI expression by insulin in adipocytes. TAFI mRNA was induced dose-dependently by insulin in 3T3-L1 adipocytes. PI3 kinase inhibitor wortmannin inhibited insulin-induced expression, but MEK1 inhibitor PD98059 had no effects. These data suggested that the gene expression of TAFI was regulated by PI3 kinase signaling pathway. Moreover, activated Akt induced the expression of TAFI mRNA to a similar extent by insulin in 3T3-L1 adipocytes expressing tamoxifen-regulatable Akt. In conclusion, TAFI was induced by insulin through PI3 kinase/Akt pathway in adipocytes. It is supposed that plasma TAFI levels are regulated at least in part by transcription levels in adipose tissues of patients with insulin resistance.

Adiponectin gene variation associates with the increasing risk of type 2 diabetes in non-diabetic Japanese subjects.

Adiponectin is an adipocyte-secreted protein that is known to modulate insulin sensitivity and glucose homeostasis. A number of genetic variations have been studied. Among them, two single-nucleotide polymorphisms (SNP45T>G, SNP276G>T) showed an association with type 2 diabetes in the Japanese population. In this study, we examined the association between these SNPs and risk factors of type 2 diabetes in 194 non-diabetic Japanese subjects. SNP45 was associated with insulin sensitivity (determined by HOMA-IR, p=0.046) and obesity (body mass index; BMI, p=0.043). SNP276 showed a stronger association with HOMA-IR (p=0.018) and BMI (p=0.017). However, neither SNP had an association with insulin secretion (insulinogenic index) and plasma lipid levels. Moreover, a linkage dis-equilibrium was observed between SNP45 and SNP276. Carriers with SNP45G-SNP276G haplotype had higher BMI (p=0.034) and carriers with SNP45T-SNP276T haplotype had lower BMI (p=0.005) and HOMA-IR (p=0.037). Adiponectin gene variations showed an association with obesity and insulin sensitivity, and adiponectin genotypes may predict the increasing risk for type 2 diabetes in non-diabetic subjects.

Metformin-induced suppression of glucose-6-phosphatase expression is independent of insulin signaling in rat hepatoma cells.

Metformin is thought to decrease blood glucose levels by reducing hepatic glucose output. To elucidate the pharmacological action of metformin on hepatic glucose production, we examined its effect on the gene expression of glucose-6-phosphatase (G6Pase), a key enzyme of gluconeogenesis, in H4IIE rat hepatoma cell line by RT-PCR and quantitative real-time PCR. Metformin suppressed dexamethasone/cAMP-induced expression of G6Pase mRNA in a dose dependent manner, its maximum effect being observed at 2 mM (79.3% inhibition, P<0.05). Pretreatment with the PI3-kinase inhibitor wortmannin, the MEK-1 inhibitor PD98059 or the protein kinase C inhibitor GF109203X had no effect on suppressed G6Pase expression by metformin. Moreover, metformin did not stimulate Akt phosphorylation. In the present study, we demonstrate that metformin suppresses G6Pase mRNA expression by a mechanism that is independent of the activation of PI3-kinase, Akt, MAP kinase and protein kinase C pathway in hepatocytes.

Increased visceral fat and serum levels of triglyceride are associated with insulin resistance in Japanese metabolically obese, normal weight subjects with normal glucose tolerance.

OBJECTIVE: The purpose of this study was to investigate the association between visceral adiposity or triglyceride (TG) metabolism and insulin resistance in metabolically obese, normal weight (MONW) Japanese individuals with normal glucose tolerance. RESEARCH DESIGN AND METHODS: We evaluated body fat areas, lipid profiles, and the glucose infusion rate (GIR) during a euglycemic-hyperinsulinemic clamp study in 20 MONW subjects (BMI <25 kg/m(2)and visceral fat areas 100 cm(2)) with normal glucose tolerance. Body fat areas were measured by computed tomography scans. Control data were obtained from 20 normal subjects (BMI <25 kg/m(2) and visceral fat areas <100 cm(2)). RESULTS: MONW subjects showed a significant increase in fasting serum levels of TG (P < 0.01) and a decrease in GIR (P < 0.01) compared with normal subjects. There were significant correlations between visceral fat areas (r = -0.563, P < 0.01) or serum levels of TG (r = -0.474, P < 0.05) and GIR in MONW subjects. Multiple regression analyses showed that visceral fat areas (F = 7.702, P < 0.02) and serum levels of TG (F = 7.114, P < 0.05) were significantly associated with GIR in all (MONW and normal) subjects. CONCLUSIONS: Increased visceral fat and serum levels of TG are associated with insulin resistance in Japanese MONW subjects with normal glucose tolerance. Excess visceral fat and elevated TG levels may play important roles in the development of insulin resistance in Japanese MONW subjects with normal glucose tolerance.

Influence of dietary intake of fish oil, magnesium, and zinc on metabolic parameters among individuals tested for diabetes.

OBJECTIVE: The aim of this study was to assess the significance and degree of correlation between the intake of fish oil, magnesium (Mg), and zinc (Zn) and metabolic parameters. METHODS: Correlation coefficients among nutrient intake and physical and laboratory parameters were determined using Spearman's rho (ρ) test or a multiple regression model among Japanese individuals (male:female, 37:66; median age, 55 y) who completed a semiquantitative food questionnaire and underwent testing for diabetes. Individuals with diabetes were excluded. RESULTS: Spearman's test revealed several weak but significant correlations between intake of fish oil including ω-3 polyunsaturated fatty acids (PUFAs) and various metabolic parameters. The test showed that Zn intake in women significantly correlated with reduced systolic blood pressure (SBP), alanine aminotransferase (ALT), γ-glutamyl transpeptidase (γ-GPT), and homeostasis model assessment-insulin resistance (HOMA-IR). Multivariate analysis revealed that intake of fish oil, eicosapentaenoic acid (EPA), and Zn was significantly associated with increased serum levels of high-density lipoprotein cholesterol (HDL-C; fish oil versus HDL-C, P = 0.0438; 95% confidence interval [CI], 0.0055-0.3724; EPA versus HDL-C, P = 0.0439; 95% CI, 0.0053-0.3724; Zn versus HDL-C, P = 0.0041; 95% CI, 0.0890-0.4609). Multivariate analysis revealed that ω-3 PUFAs were associated with decreased serum ALT levels (P = 0.0240; 95% CI, -5.000 to -0.0367) and that Zn correlated with SBP (P = 0.0239; 95% CI, -0.5149 to -0.0377) in women. CONCLUSION: Intake of fish oil, Mg, and Zn was associated with some metabolic parameters. Abundant intake of fish oil including ω-3 PUFAs and Zn can exert antiarteriosclerotic effects through increasing serum levels of HDL-C. ω-3 PUFAs can reduce liver inflammation and Zn can reduce SBP in women.

Effects of sugar-sweetened beverage intake on the development of type 2 diabetes mellitus in subjects with impaired glucose tolerance: the Mihama diabetes prevention study.

In Japan, the incidence of type 2 diabetes mellitus (T2DM) is increasing for several reasons, including increased consumption of sugar-sweetened beverages (SSBs). However, whether SSBs cause T2DM by excess of energy production resulting in obesity remains unclear. Therefore, the present study was designed to evaluate the effects of SSB intake on the development of T2DM in subjects with impaired glucose tolerance (IGT). Ninety-three subjects (30 males and 63 females) with IGT aged 40-69 y and residing in the Mihama district (southern Mie Prefecture, Japan) were included in the study. The mean observational period was 3.6 y. All subjects underwent the 75-g oral glucose tolerance test (OGTT) and completed a lifestyle questionnaire survey related to SSB intake. OGTT results and SSB intake were evaluated before and after the observational period. In addition, the correlation between SSB intake and development of T2DM was investigated. Of the 93 subjects, 20 (21.5%) developed T2DM (T2DM group) and demonstrated a significantly high SSB intake compared with the group that did not develop the disease (non-T2DM group). The odds ratio for the incidence of T2DM based on SSB intake was 3.26 (95% confidence interval, 1.17-9.06). The body mass index (BMI; kg/m(2)) and the homeostasis model assessment for insulin resistance (HOMA-R) values was significantly higher in the T2DM group than in the non-T2DM group, while the insulinogenic indices were significantly lower in the former than in the latter group. The sum of insulin secretion levels during OGTT was not significantly different between groups. SSB intake correlated with the predisposition for developing T2DM, possibly by influencing body weight, insulin resistance, and the ability of the pancreatic beta cells to effectively compensate for the insulin resistance.