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Failure of pancreatic beta-cells is the common characteristic of type 1 and type 2 diabetes. Type 1 diabetes mellitus is induced by destruction of pancreatic beta-cells which is mediated by an autoimmune mechanism and consequent inflammatory process. Various inflammatory cytokines and oxidative stress are produced during this process, which has been proposed to play an important role in mediating beta-cell destruction. The JNK pathway is also activated by such cytokines and oxidative stress, and is involved in beta-cell destruction. Type 2 diabetes is the most prevalent and serious metabolic disease, and beta-cell dysfunction and insulin resistance are the hallmark of type 2 diabetes. Under diabetic conditions, chronic hyperglycemia gradually deteriorates beta-cell function and aggravates insulin resistance. This process is called "glucose toxicity". Under such conditions, oxidative stress is provoked and the JNK pathway is activated, which is likely involved in pancreatic beta-cells dysfunction and insulin resistance. In addition, oxidative stress and activation of the JNK pathway are also involved in the progression of atherosclerosis which is often observed under diabetic conditions. Taken together, it is likely that oxidative stress and subsequent activation of the JNK pathway are involved in the pathogenesis of type 1 and type 2 diabetes.

It is well known that pancreatic and duodenal homeobox gene-1 (PDX-1) plays a crucial role in beta-cell differentiation, and maintaining mature beta-cell function. Thus, it is important to understand how pdx-1 gene is regulated under various pathophysiological conditions in vivo. In this study, to non-invasively and quantitatively monitor pdx-1 promoter activity in vivo, we constructed a pdx-1 promoter-SEAP-IRES-GFP reporter plasmid. In this construct, the -4.6kb pdx-1 promoter region sufficient for driving beta-cell-selective PDX-1 expression was inserted to the upstream of the secreted alkaline phosphatase (SEAP) reporter gene. It is noted here that the pdx-1 promoter-mediated SEAP activity can be distinguished from endogenous alkaline phosphatase activity. First, we transfected the construct in mouse beta-cell line MIN6 and human hepatocellular carcinoma cell line HepG2. SEAP activity was readily detected in the media of MIN6 cells, but not in HepG2 cells. These results indicate that this construct specifically reports beta-cell-specific pdx-1 promoter activity in a cell culture system. Based on these in vitro findings, we next generated transgenic mice using the same construct. SEAP activity was readily detected in serum of the transgenic mice, but not in their littermate mice. Furthermore, SEAP activity was detected in protein extract from the transgenic pancreas and slightly from the transgenic duodenum, but not from the liver, and brain. These results indicate that serum SEAP activity likely represents in vivo pdx-1 promoter activity. This transgenic mouse model would be useful to non-invasively monitor in vivo pdx-1 promoter activity and to screen new molecules which regulate PDX-1 expression.

Insulin resistance is the principal cause of glucose intolerance and type 2 diabetes and induces progression of severe atherosclerosis in these patients. Adiponectin, the adipose-specific proteins, is known to correlate negatively with insulin resistance in patients with obesity and type 2 diabetes. The purpose of this study was to evaluate the potential of using serum adiponectin levels as a marker of insulin resistance in various states of insulin resistance. Furthermore, we attempted to establish a modified index of the homeostasis model assessment index (HOMA-IR), calculated from the product of serum insulin and plasma glucose levels divided by serum adiponectin levels (HOMA-AD). We recruited 117 Japanese subjects with various degrees of glucose tolerance and determined serum adiponectin levels and insulin sensitivity (M-value) by using the euglycemic hyperinsulinemic clamp technique. M-value, the gold standard index of insulin resistance, correlates significantly and independently with fasting insulin (r=-0.313, P<0.001), glucose (r=-0.319, P<0.001), and adiponectin (r=0.241, P<0.002) levels. M-values were more significantly correlated with HOMA-AD (r=-0.643, P<0.001) than HOMA-IR values (r=-0.591, P<0.001). In subjects with moderate hyperglycemia (fasting glucose levels>8.0mmol/L, n=30), HOMA-AD showed a more significant correlation with the M-value than HOMA-IR (r=-0.535, P=0.005 versus r=-0.461, P=0.010). We would therefore like to propose a novel index, HOMA-AD, as a simple and adequate index for determining insulin resistance even in diabetic patients with overt hyperglycemia.

Pancreatic beta-cell failure is the common characteristic of type 1 and type 2 diabetes. Type 1 diabetes is induced by pancreatic beta-cell destruction, which is mediated by an autoimmune mechanism and consequent inflammatory process. Various inflammatory cytokines and oxidative stress produced by islet-infiltrating immune cells have been proposed to play an important role in mediating the destruction of beta cells. The JNK pathway is also activated by such cytokines and oxidative stress and is involved in beta-cell destruction. Type 2 diabetes is the most prevalent and serious metabolic disease affecting people all over the world. Pancreatic beta-cell dysfunction and insulin resistance are the hallmark of type 2 diabetes. Once hyperglycemia becomes apparent, beta-cell function gradually deteriorates, and insulin resistance is aggravated. This process is called "glucose toxicity." Under such conditions, oxidative stress is provoked, and the JNK pathway is activated, which is likely involved in pancreatic beta-cell dysfunction and insulin resistance. In addition, oxidative stress and activation of the JNK pathway are involved in the progression of atherosclerosis, which is often observed under diabetic conditions. Taken together, it is likely that oxidative stress and subsequent activation of the JNK pathway are involved in the pathogenesis of type 1 and type 2 diabetes.

The hallmarks of type 2 diabetes are pancreatic beta-cell dysfunction and insulin resistance. It has been suggested that Rho/Rho-kinase is a mediator of insulin signaling, and thereby involved in the development of insulin resistance, regulation of insulin action, and glucose homeostasis, but the role of Rho/Rho-kinase in beta-cells remained unknown. The aim of this study was to examine the possible role of Rho/Rho-kinase in beta-cell function. Immunostaining showed that RhoA was expressed in mature beta-cells, with higher expression observed in beta-cells of diabetic C57BL/KsJ-db/db mice compared to non-diabetic mice. In addition, to examine the functional role of Rho/Rho-kinase in beta-cells, we evaluated the effect of Rho-kinase inhibitors on insulin biosynthesis. Northern blot analysis showed that insulin mRNA levels were markedly increased by Rho-kinase inhibitors, Y-27632 and fasudil, in beta-cell-derived HIT-T15 cells. Furthermore, using the luciferase reporter gene assay, insulin promoter activity was also dramatically increased by Y-27632, which was associated with an increase in the insulin mRNA level. These results suggest that suppression of Rho/Rho-kinase increases insulin promoter activity, which leads to an increase in insulin mRNA level. Taken together, Rho/Rho-kinase is activated in beta-cells under diabetic conditions and suppression of the Rho/Rho-kinase pathway increases insulin gene transcription. These results imply that Rho/Rho-kinase activation is involved in the suppression of insulin expression found in diabetes and that suppression of the Rho/Rho-kinase pathway could be a useful tool to augment insulin gene transcription.

Objective: Several genetic risk factors, such as single nucleotide polymorphisms (SNPs), in candidate genes have been reported to be responsible for intima-media thickness (IMT), which is one of the surrogate end points of cardiovascular events. However, the synergistic effects of SNPs have not been evaluated in detail., Research Design and Methods: We measured the average IMT of the common and internal carotid artery in Japanese type 2 diabetic patients (n = 690) (>50 years old) using ultrasonography. We also determined their genotypes regarding 106 SNPs in candidate genes responsible for cardiovascular diseases. Among the 106 SNPs, we selected 40 common (frequency of minor allele >/=10%) SNPs. We compared the average IMT of subjects with and without any pairs of four genotypes selected from the 40 common SNPs., Results: The combination of methylen-tetrahydrofolate reductase 677 TT genotype and lymphotoxin-alpha (LTA) 252 GG genotype and that of ACE DD genotype and LTA 252 GG genotype were evaluated as responsible for a statistically significant (P = 2.7 x 10(-9) and 3.5 x 10(-6), respectively) increase in average IMT (mean [+/-SD] 1.54 +/- 0.60 and 1.43 +/- 0.58 mm, respectively) compared with those of the subjects without these combinations (1.04 +/- 0.34 and 1.04 +/- 0.34 mm, respectively). No single genotype was shown to be responsible for the statistically significant difference in average IMT after Bonferroni's multiple comparison procedure., Conclusions: The present analysis demonstrates an approach to evaluate combinations of multiple genetic risk factors that are synergistically associated with carotid atherosclerosis.

Nateglinide, a rapid insulin secretagogue, is known to facilitate the early phase of insulin secretion and has been used for the treatment of type 2 diabetic patients with postprandial hyperglycemia. The aim of this study is to evaluate the effect of nateglinide on insulin resistance as well as insulin secretory defects in type 2 diabetic patients. Insulin secretion ability was evaluated by the hyperglycemic clamp test, and insulin sensitivity was evaluated by the euglycemic hyperinsulinemic clamp test, using an artificial pancreas. The hyperglycemic clamp test showed that a 7-day treatment with nateglinide significantly increased insulin secretion in response to high glucose. Interestingly, although nateglinide is known to facilitate insulin secretion, daily urinary C-peptide excretion was decreased after nateglinide treatment. Moreover, in the euglycemic hyperinsulinemic clamp test, glucose infusion rate was significantly increased by nateglinide treatment, indicating that nateglinide functions to decrease insulin resistance. Nateglinide ameliorates insulin resistance as well as insulin secretory defects in type 2 diabetic patients.

It has been shown that oxidative stress and activation of the c-Jun N-terminal kinase (JNK) pathway induce the nucleocytoplasmic translocation of the pancreatic transcription factor PDX-1, which leads to pancreatic beta-cell dysfunction. In this study, we have shown that the forkhead transcription factor Foxo1/FKHR plays a role as a mediator between the JNK pathway and PDX-1. Under oxidative stress conditions, Foxo1 changed its intracellular localization from the cytoplasm to the nucleus in the pancreatic beta-cell line HIT-T15. The overexpression of JNK also induced the nuclear localization of Foxo1, but in contrast, suppression of JNK reduced the oxidative stress-induced nuclear localization of Foxo1, suggesting the involvement of the JNK pathway in Foxo1 translocation. In addition, oxidative stress or activation of the JNK pathway decreased the activity of Akt in HIT cells, leading to the decreased phosphorylation of Foxo1 following nuclear localization. Furthermore, adenovirus-mediated Foxo1 overexpression reduced the nuclear expression of PDX-1, whereas repression of Foxo1 by Foxo1-specific small interfering RNA retained the nuclear expression of PDX-1 under oxidative stress conditions. Taken together, Foxo1 is involved in the nucleocytoplasmic translocation of PDX-1 by oxidative stress and the JNK pathway.

Type 2 diabetes is the most prevalent and serious metabolic disease affecting people all over the world. Pancreatic beta-cell dysfunction and insulin resistance are the hallmark of type 2 diabetes. Normal beta-cells can compensate for insulin resistance by increasing insulin secretion and/or beta-cell mass, but insufficient compensation leads to the onset of glucose intolerance. Once hyperglycemia becomes apparent, beta-cell function gradually deteriorates and insulin resistance aggravates. Under diabetic conditions, oxidative stress and endoplasmic reticulum stress are induced in various tissues, leading to activation of the c-Jun N-terminal kinase pathway. The activation of c-Jun N-terminal kinase suppresses insulin biosynthesis and interferes with insulin action. Indeed, suppression of c-Jun N-terminal kinase in diabetic mice improves insulin resistance and ameliorates glucose tolerance. Thus, the c-Jun N-terminal kinase pathway plays a central role in pathogenesis of type 2 diabetes and could be a potential target for diabetes therapy.

Objective: The binding of advanced glycation end products (AGEs) to their receptor (RAGE) plays an important role in the development of diabetic vascular complications. In the present study, we examined circulating endogenous secretory RAGE (esRAGE) levels in subjects with type 1 diabetes and explored the possible association between esRAGE levels and the severity of diabetic vascular complications., Research Design and Methods: Circulating esRAGE levels in serum were examined in 67 Japanese type 1 diabetic patients (22 men and 45 women, age 24.0 +/- 4.4 years [means +/- SD]) and 23 age-matched healthy nondiabetic subjects (10 men and 13 women aged 24.9 +/- 1.4 years). Daily urinary albumin excretion, the presence of retinopathy, and intima-media thickness (IMT) of the carotid artery were also evaluated. We further explored the association between esRAGE levels and severity of diabetic vascular complications., Results: Circulating esRAGE levels were significantly lower in subjects with type 1 diabetes than in nondiabetic subjects (0.266 +/- 0.089 vs. 0.436 +/- 0.121 ng/ml, respectively, P < 0.0001) and was inversely correlated with HbA(1c) (A1C) levels (r = -0.614, P < 0.0001). In addition, multivariate regression analysis demonstrated that A1C was an independent risk factor for a low esRAGE value. Furthermore, circulating esRAGE levels were inversely correlated with carotid IMT (r = -0.325, P = 0.0017) and was one of the independent risk factors for IMT thickening. Furthermore, there was a significant difference (P = 0.0124) in esRAGE levels between patients without retinopathy (0.286 +/- 0.092 ng/ml) and those with retinopathy (0.230 +/- 0.074 ng/ml)., Conclusions: Circulating esRAGE levels were significantly lower in type 1 diabetic patients than in nondiabetic subjects and were inversely associated with the severity of some diabetic vascular complications.

Diabetic microangiopathy is often observed in diabetic patients, but there is little evidence regarding the relationship between post-prandial glycemia or insulinemia and the incidence of diabetic microangiopathy. In this study, to elucidate the relationship between post-prandial glycemia (or insulinemia) and diabetic microangiopathy, we performed a cross-sectional study of 232 subjects with type 2 diabetes mellitus who were not being treated with insulin injections. A multiple regression analysis showed that post-prandial hyperglycemia independently correlated with the incidence of diabetic retinopathy and neuropathy. Post-prandial hyperglycemia also correlated, although not independently, with the incidence of diabetic nephropathy. In addition, interestingly, post-prandial hypoinsulinemia independently correlated with the incidence of diabetic retinopathy, although not correlated with diabetic neuropathy or nephropathy. In conclusion, post-prandial hyperglycemia, rather than fasting glycemia or hemoglobin A1c levels, is an important predictor of the incidence of diabetic microangiopathy in Japanese type 2 diabetic patients.

Peripheral vascular disease (PVD) has been reported to cause deterioration in insulin sensitivity. The precise mechanism of insulin resistance induced by PVD has not been clarified. To elucidate the mechanism causing impaired insulin action and glucose metabolism under peripheral ischemic conditions, we determined glucose turnover and glucose tolerance in hindlimb-ischemic (FAL) rats. The right femoral artery was ligated in hindlimb-ischemic (FAL) rats, while the artery was only exposed in the Sham operated (Sham) rats used as a control. Two weeks after the ligation, glucose tolerance was impaired and plasma insulin levels were significantly increased in FAL rats compared with Sham rats after intraperitoneal glucose loading (2 g kg(-1)). Under euglycemic hyperinsulinemic clamp conditions, the glucose infusion rate was significantly lower in FAL rats compared with Sham rats, but there was no significant difference in the glucose disappearance rate between the two groups. Hyperinsulinemia suppressed endogenous glucose production by 50% in Sham rats, while the suppression was 20% in FAL rats, indicating hepatic insulin resistance in FAL rats. mRNA analysis of isolated liver after the clamp experiment revealed that glucokinase mRNA, but not PEPCK and glucose-6-phosphatase mRNA, was significantly lower in FAL rats compared with Sham rats. In conclusion, chronic hindlimb ischemia impaired glucose tolerance associated with insulin resistance in the liver rather than the peripheral tissues.

Type 2 diabetes is the most prevalent and serious metabolic disease affecting people all over the world. Pancreatic beta-cell dysfunction and insulin resistance are the hallmark of type 2 diabetes. Normal beta-cells can compensate for insulin resistance by increasing insulin secretion and/or beta-cell mass, but insufficient compensation leads to the onset of glucose intolerance. Once hyperglycemia becomes apparent, beta-cell function gradually deteriorates and insulin resistance aggravates. Under diabetic conditions, oxidative stress and endoplasmic reticulum stress are induced in various tissues, leading to activation of the c-Jun N-terminal kinase pathway. The activation of c-Jun N-terminal kinase suppresses insulin biosynthesis and interferes with insulin action. Indeed, suppression of c-Jun N-terminal kinase in diabetic mice improves insulin resistance and ameliorates glucose tolerance. Thus, the c-Jun N-terminal kinase pathway plays a central role in pathogenesis of type 2 diabetes and could be a potential target for diabetes therapy.

The hallmark of type 2 diabetes is insulin resistance and insufficient insulin secretion, and appropriate therapy should be selected for each patient. In this study, to establish some index to select suitable therapy for each patient, we evaluated insulin sensitivity and insulin secretion with euglycemic hyperinsulinemic clamp and hyperglycemic clamp tests, respectively, and found that specific GIR index (GIRxIRI (90)) could be a useful marker to select suitable therapy for each type 2 diabetic patient (GIR: glucose infusion rate in euglycemic hyperinsulinemic clamp test; IRI (90): plasma insulin level 90 min after starting the hyperglycemic clamp test).

Pancreatic beta-cell dysfunction and insulin resistance are observed in type 2 diabetes. Under diabetic conditions, oxidative stress and ER stress are induced in various tissues, leading to activation of the JNK pathway. This JNK activation suppresses insulin biosynthesis and interferes with insulin action. Indeed, suppression of the JNK pathway in diabetic mice improves insulin resistance and ameliorates glucose tolerance. Thus, the JNK pathway plays a central role in pathogenesis of type 2 diabetes and may be a potential target for diabetes therapy.

The insulin resistance found in diabetes is influenced by vascular tone and local blood flow. Endothelial-derived hyperpolarizing factor (EDHF) functions as a potent vasodilator to regulate vascular tone, and its production is regulated by soluble epoxide hydrolase (sEH). In this study, we examined the genotype distribution and allele frequency of sEH gene G860A (Arg287Gln) polymorphism in Japanese subjects (n=499) (non-diabetic subjects, n=205; type 2 diabetic patients, n=294). Also, to accurately evaluate insulin resistance, we performed the euglycemic hyperinsulinemic clamp test for each type 2 diabetic patient (n=86) from whom agreement was obtained, and then examined a possible association of sEH gene G860A polymorphism with insulin resistance status. There was no significant difference in genotype distribution and allele frequency between non-diabetic subjects and type 2 diabetic patients. Interestingly, however, there was close association of sEH gene G860A (Arg287Gln) polymorphism with insulin resistance in type 2 diabetic patients, which was not observed in non-diabetic subjects. These results suggest that sEH and EDHF play some important role in the pathogenesis of insulin resistance found in type 2 diabetes.

MafA, a recently isolated pancreatic beta-cell-specific transcription factor, is a potent activator of insulin gene transcription. In this study, we show that MafA overexpression, together with PDX-1 (pancreatic and duodenal homeobox factor-1) and NeuroD, markedly increases insulin gene expression in the liver. Consequently, substantial amounts of insulin protein were induced by such combination. Furthermore, in streptozotocin-induced diabetic mice, MafA overexpression in the liver, together with PDX-1 and NeuroD, dramatically ameliorated glucose tolerance, while combination of PDX-1 and NeuroD was much less effective. These results suggest a crucial role of MafA as a novel therapeutic target for diabetes.

Diabetes is the most prevalent and serious metabolic disease, and the number of diabetic patients worldwide is increasing. The reduction of insulin biosynthesis in pancreatic beta-cells is closely associated with the onset and progression of diabetes, and thus it is important to search for ways to induce insulin-producing cells in non-beta-cells. In this study, we showed that a modified form of the pancreatic and duodenal homeobox factor 1 (PDX-1) carrying the VP16 transcriptional activation domain (PDX-1/VP16) markedly increases insulin biosynthesis and induces various pancreas-related factors in the liver, especially in the presence of NeuroD or neurogenin 3 (Ngn3). Furthermore, in streptozotocin-induced diabetic mice, PDX-1/VP16 overexpression, together with NeuroD or Ngn3, drastically ameliorated glucose tolerance. Thus PDX-1/VP16 expression, together with NeuroD or Ngn3, markedly induces insulin gene transcription and ameliorates glucose tolerance. This approach warrants further investigation and may have utility in the treatment of diabetes.

To determine the role of the endoplasmic reticulum (ER) in diabetes, Akita mice, a mouse model of type 2 diabetes, were mated with either heterozygous knockout mice or two types of transgenic mice of 150-kDa oxygen-regulated protein (ORP150), a molecular chaperone located in the ER. Systemic expression of ORP150 in Akita mice improves insulin intolerance, whereas the exclusive overexpression of ORP150 in pancreatic beta-cells of Akita mice did not change their glucose tolerance. Both an insulin tolerance test and hyperinsulinemic-euglycemic clamp revealed that ORP150 enhanced glucose uptake, accompanied by suppression of oxidized protein. Furthermore, ORP150 enhanced the insulin sensitivity of myoblast cells treated with hydrogen peroxide. These data suggest that ORP150 plays an important role in insulin sensitivity and is a potential target for the treatment of diabetes.

Objective: An open randomized prospective study was performed to elucidate the effect of an alpha-glucosidase inhibitor, voglibose, on the progression of atherosclerosis in subjects with type 2 diabetes., Research Design and Methods: Voglibose at a dose of 0.4-0.6 mg/day was added on 51 subjects out of 101 type 2 diabetic patients being treated with diet, sulphonylurea (SU) or insulin injections, and the average (AveIMT) and maximum intima-media thickness (MaxIMT) of their carotid arteries were examined for 3 years., Results: Irrespective of the differences in treatments, addition of voglibose reduced the progression of AveIMT and MaxIMT to -0.024 +/- 0.047 (+/-S.D.) and -0.021 +/- 0.144 mm/year, respectively. Without voglibose, diabetic patients showed significant (P < 0.0001) progression of AveIMT and MaxIMT (0.056 +/- 0.046 and 0.098 +/- 0.122 mm/year, respectively). The administration of voglibose resulted in a significant reduction of hemoglobin A1c (HbA1c), total cholesterol and triglyceride concentrations, as well as an increase in HDL cholesterol concentration. Multivariate regression analysis showed that administration of voglibose independently reduced the progression of AveIMT by 0.069 mm/year (P < 0.0001)., Conclusions: These results suggest that voglibose reduces the progression of IMT and may be a candidate for an anti-atherosclerotic drug for type 2 diabetic patients.

Under diabetic conditions, oxidative stress is induced and the JNK pathway is activated, which is involved in deterioration of pancreatic beta-cell function found in diabetes. Oxidative stress and/or activation of the JNK pathway suppress insulin gene expression, accompanied by reduction of PDX-1 DNA binding activity. Treatment with antioxidants and/or suppression of the JNK pathway protect beta-cells from some of the toxic effects of hyperglycemia. The JNK pathway is also involved in the progression of insulin resistance; suppression of the JNK pathway in obese diabetic mice markedly improves insulin resistance and ameliorates glucose tolerance. The phosphorylation state of key molecules for insulin signaling is altered upon modification of the JNK pathway. Taken together, the JNK pathway plays a crucial role in progression of insulin resistance as well as beta-cell dysfunction found in diabetes and thus could be a potential therapeutic target for diabetes.

Type 2 diabetes is one of the most prevalent and serious metabolic diseases in the world, and insulin resistance and pancreatic beta-cell dysfunction are the hallmarks of the disease. In this study, we have shown that endoplasmic reticulum (ER) stress, which is provoked under diabetic conditions, plays a crucial role in the insulin resistance found in diabetes by modifying the expression of oxygen-regulated protein 150 (ORP150), a molecular chaperone that protects cells from ER stress. Sense ORP overexpression in the liver of obese diabetic mice significantly improved insulin resistance and markedly ameliorated glucose tolerance. Conversely, expression of antisense ORP150 in the liver of normal mice decreased insulin sensitivity. The phosphorylation state of IRS-1 and Akt, which are key molecules for insulin signaling, and the expression levels of phosphoenolpyruvate carboxykinase and glucose-6-phosphatase, key enzymes of gluconeogenesis, were also altered by ORP150 overexpression. This is the first report showing that ER stress plays a crucial role in the insulin resistance found in diabetes and thus could be a potential therapeutic target for diabetes.

The proliferation of vascular smooth muscle cells (VSMCs) and alterations of their phenotype are implicated in the pathogenesis of atherosclerosis. Arterial wall injury induces the expression of proto-oncogenes, leading to the proliferation of VSMCs. In particular, c-Myc and c-Myb play a central role in cell cycle progression and are essential for VSMC replication. The protooncogene Pim-1 cooperates with c-Myc and enhances the transcriptional activity of c-Myb in hematopoietic cells, suggesting that Pim-1 is involved in cell cycle regulation. The aim of this study was to examine the possible involvement of Pim-1 in VSMC proliferation. Pim-1 was substantially induced in neointimal VSMCs of balloon-injured rat carotid arteries, and in vivo infection with a dominant negative Pim-1-expressing adenovirus (Ad-DN-Pim-1) markedly suppressed neointima formation and cell cycle progression in the balloon-injured arteries. In cultured VSMCs, treatment with serum or H(2)O(2) induced Pim-1 expression, and H(2)O(2)- or serum-stimulated cell cycle progression and DNA synthesis were almost completely inhibited by DN-Pim-1 overexpression. Furthermore, we performed immunohisto-chemical staining for Pim-1 in human thoracic aortas and coronary arteries obtained from six individuals at autopsy and found that Pim-1-positive cells are observed predominantly in the thickened intima of the aortas and coronary arteries. To the best of our knowledge, this is the first report showing Pim-1 expression in rodent and human arterial walls. To summarize, Pim-1 expression was observed in the neointima of balloon-injured rat carotid arteries and in human thoracic aortas and coronary arteries showing intimal thickening, and the specific inhibition of Pim-1 function markedly suppressed neointima formation after balloon injury and the proliferation of cultured VSMCs, suggesting that Pim-1 plays a role in VSMC proliferation.

To investigate the dose-dependent effect of free fatty acid (FFA) on the hepatic glucose uptake (HGU), we determined hepatic glucose fluxes by a dual tracer technique during the basal state and euglycemic hyperinsulinemic clamp combined with a portal glucose load in three groups of rats given saline (saline), low-dose lipid (lipid-L), or high-dose lipid infusion (lipid-H). In the basal state, lipid infusion dose-dependently increased plasma FFA (saline, 400 +/- 50; lipid-L, 550 +/- 30; lipid-H, 1700 +/- 270 micromol l(-1); mean +/- S.E). Endogenous glucose production (EGP) in lipid-H was 63.5 +/- 5.5 micromol kg(-1) min(-1) and significantly higher than in the saline and lipid-L (40.2 +/- 2.9, 47.6 +/- 3.1 micromol kg(-1) min(-1), respectively). During euglycemic hyperinsulinemic clamp, plasma FFA decreased to 130 +/- 30 micromol l(-1) in saline, but remained at basal levels in lipid-L and lipid-H (470 +/- 30 and 1110 +/- 180 micromol l(-1), respectively). Insulin-suppressed EGP was complete in saline and lipid-L, but impaired in lipid-H (38.0 +/- 6.4 micromol kg(-1) min(-1)). Elevated FFA dose-dependently reduced HGU (saline, 12.2 +/- 0.9; lipid-L, 8.6 +/- 0.6; lipid-H, 4.7 +/- 1.4 micromol kg(-1) min(-1)). In conclusion, acutely elevated FFA impairs HGU as well as insulin-mediated suppression of EGP during hyperinsulinemic clamp with portal glucose loading. Impaired hepatic glucose uptake associated with elevated FFA may contribute to the development of insulin resistance in obesity and type 2 diabetes.

The c-Jun N-terminal kinase (JNK) pathway is known to be activated under diabetic conditions and to possibly be involved in the progression of insulin resistance. In this study, we examined the effects of modulation of the JNK pathway in liver on insulin resistance and glucose tolerance. Overexpression of dominant-negative type JNK in the liver of obese diabetic mice dramatically improved insulin resistance and markedly decreased blood glucose levels. Conversely, expression of wild type JNK in the liver of normal mice decreased insulin sensitivity. The phosphorylation state of crucial molecules for insulin signaling was altered upon modification of the JNK pathway. Furthermore, suppression of the JNK pathway resulted in a dramatic decrease in the expression levels of the key gluconeogenic enzymes, and endogenous hepatic glucose production was also greatly reduced. Similar effects were observed in high fat, high sucrose diet-induced diabetic mice. Taken together, these findings suggest that suppression of the JNK pathway in liver exerts greatly beneficial effects on insulin resistance status and glucose tolerance in both genetic and dietary models of diabetes.

The JNK pathway is known to be activated in several tissues in the diabetic state, and is possibly involved in the development of insulin resistance and suppression of insulin biosynthesis. Here we show a potential new therapy for diabetes using cell-permeable JNK-inhibitory peptide. Intraperitoneal administration of the peptide led to its transduction into various tissues in vivo, and this treatment markedly improved insulin resistance and ameliorated glucose tolerance in diabetic mice. These data indicate that the JNK pathway is critically involved in diabetes and that the cell-permeable JNK-inhibitory peptide may have promise as a new therapeutic agent for diabetes.

We previously reported that insulin receptor substrate-2 (IRS-2)-deficient mice develop diabetes as a result of insulin resistance in the liver and failure of beta-cell hyperplasia. In this study we introduced the IRS-2 gene specifically into the liver of Irs2(-/-) mice with adenovirus vectors. Glucose tolerance tests revealed that the IRS-2 restoration in the liver ameliorated the hyperglycemia, but the improvement in hyperinsulinemia was only partial. Endogenous glucose production (EGP) and the rate of glucose disappearance (Rd) were measured during hyperinsulinemic-euglycemic clamp studies: EGP was increased 2-fold in the Irs2(-/-) mice, while Rd decreased by 50%. Restoration of IRS-2 in the liver suppressed EGP to a level similar to that in wild-type mice, but Rd remained decreased in the Adeno-IRS-2-infected Irs2(-/-) mice. Irs2(-/-) mice also exhibit obesity and hyperleptinemia associated with impairment of hypothalamic phosphatidylinositol 3-kinase activation. Continuous intracerebroventricular leptin infusion or caloric restriction yielded Irs2(-/-) mice whose adiposity was comparable to that of Irs2(+/+) mice, and both the hyperglycemia and the hyperinsulinemia of these mice improved with increased Rd albeit partially. Finally combination treatment consisting of adenovirus-mediated gene transfer of IRS-2 and continuous intracerebroventricular leptin infusion completely reversed the hyperglycemia and hyperinsulinemia in Irs2(-/-) mice. EGP and Rd also became normal in these mice as well as in mice treated by caloric restriction plus adenoviral gene transfer. We therefore concluded that a combination of increased EGP due to insulin signaling defects in the liver and reduced Rd due to obesity accounts for the systemic insulin resistance in Irs2(-/-) mice.

Objective: This study was conducted to examine whether tissue characterization of the carotid artery wall by determining integrated backscatter (IBS) can identify subjects with a recent history of acute coronary syndrome (ACS) or atherothrombotic infarction (ATI)., Research Design and Methods: The maximum thickness (Max-IMT) and IBS value (corrected-IBS) of the carotid artery intima-media complex were measured ultrasonographically for 132 type 2 diabetic subjects (62.9+/-8.5 (+/-S.D.) years old, 87 men and 45 women) with or without cardiovascular diseases., Results: The diabetic patients with recent ACS or ATI had a significantly lower corrected-IBS and higher Max-IMT than those with Max-IMT > or = 1.1mm but without cardiovascular diseases. The product of Max-IMT and corrected-IBS (IMT-IBS product) of the patients with recent ACS was significantly lower than that of the patients with chronic stable angina. The multiple logistic model showed that only the IMT-IBS product was associated with a recent history of ACS (odds ratio 0.94, P<0.05) and ATI (odds ratio 0.90, P<0.005)., Conclusions: Diabetic patients who had a recent history of ACS or ATI showed a lower IBS value and higher IMT for their carotid artery. Both the size and tissue characteristics of the carotid plaque may identify subjects with a high risk of cardiovascular disease.

We report a rare case of psoas abscess caused by Candida albicans. A 59-year-old man with diabetes mellitis presented with right flank mass. Computed tomography (CT) showed a psoas abscess. Needle aspiration of the right flank mass revealed pus which was proved to be C. albicans by culture. The literature is briefly reviewed.

Brain-derived neurotrophic factor (BDNF), a member of the neurotrophins, has been reported to ameliorate hyperglycemia in obese diabetic animal models. To elucidate the mechanism of BDNF on glucose metabolism, we determined the glucose turnover under basal and euglycemic hyperinsulinemic (insulin infusion rate, 54 pmol. kg(-1). min(-1)) clamp conditions in obese insulin-resistant rats, male Zucker fatty rats, which had been acutely administered a subcutaneous injection of BDNF (20 mg/kg) (n = 9, BDNF) or vehicle (n = 8, vehicle). Under the basal condition, acute administration of BDNF did not affect the blood glucose level, plasma insulin level, rate of glucose disappearance (Rd), and endogenous glucose production (EGP). Under the clamp condition, the glucose infusion rate (GIR) was significantly higher in BDNF than in vehicle (mean +/- SD, 61.4 +/- 19.1 v 41.4 +/- 4.9 micromol. kg(-1). min(-1), P <.05). There was no significant difference in Rd and EGP between the 2 groups under the clamp condition, but the insulin-mediated suppression ratio of endogenous glucose production in BDNF was significantly greater than in vehicle (48.9 +/- 22.2 v 22.4% +/- 20.6%, P <.05). In BDNF, mRNA expressions of hepatic phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) were comparable to those of vehicle, while hepatic glucokinase (GK) mRNA expression was significantly higher (1.57 +/- 0.33 v 1.03 +/- 0.17, P <.05). We conclude that BDNF mainly improves hepatic insulin resistance in obese insulin-resistant rats, probably by affecting the hepatic GK flux., (Copyright 2003, Elsevier Science (USA). All rights reserved.)

Objective: To evaluate whether low-grade inflammation contributes to early-stage advanced carotid atherosclerosis in young subjects with type 1 diabetes., Research Design and Methods: The mean and maximum (max) intima-media thicknesses (IMT) of the carotid artery were assessed using ultrasound B-mode imaging in 55 patients with type 1 diabetes (22 men and 33 women, aged 22.1 +/- 3.6 years (+/- SD), duration of diabetes 14.2 +/- 5.7 years) and 75 age-matched healthy nondiabetic subjects (28 men and 47 women). High-sensitive C-reactive protein (hs-CRP) levels were measured with a latex-enhanced immunonephelometer., Results: The patients with type 1 diabetes had significantly higher hs-CRP levels (median 0.35, range 0.05-1.47 mg/l vs. median 0.14, range 0.05-1.44 mg/l; P = 0.001) as well as significantly higher mean IMT and max IMT than the nondiabetic subjects (mean IMT 0.76 +/- 0.09 vs. 0.72 +/- 0.04 mm, P = 0.003; max IMT 0.84 +/- 0.11 vs. 0.77 +/- 0.06 mm, P < 0.0001). Hs-CRP levels were significantly correlated with the mean and max IMT of patients with type 1 diabetes and with the max IMT of nondiabetic patients. Multivariate regression analyses for both diabetic and nondiabetic subjects as a single group showed that hs-CRP levels are independently correlated with the mean IMT and max IMT levels (P = 0.002 and P = 0.023, respectively) as well as with diastolic blood pressure, sex, and duration of diabetes., Conclusions: Our data indicate that hs-CRP levels are elevated in young patients with type 1 diabetes, possibly corresponding with early-stage advanced carotid atherosclerosis.

Oxidative stress is induced under diabetic conditions and causes various forms of tissue damage in patients with diabetes. Recently, pancreatic beta-cells have emerged as a putative target of oxidative stress-induced tissue damage and this seems to explain in part the progressive deterioration of beta-cell function in type 2 diabetes. As a step toward clinical trial of antioxidant for type 2 diabetes, we investigated the possible anti-diabetic effects of probucol, an antioxidant widely used as an anti-hyperlipidemic agent, on preservation of beta-cell function in diabetic C57BL/KsJ-db/db mice. Probucol-containing diet was given to mice from 6 to 16 weeks of age. Immunostaining for oxidative stress markers such as 4-hydroxy-2-nonenal (HNE)-modified proteins and heme oxygenase-1 revealed that probucol treatment decreased reactive oxygen species (ROS) in pancreatic islets of diabetic animals. Oxidative stress is known to enhance apoptosis of beta-cells and to suppress insulin biosynthesis, but probucol treatment led to preservation of beta-cell mass and the insulin content. According to intraperitoneal glucose tolerance tests, the probucol treatment preserved glucose-stimulated insulin secretion and improved glucose tolerance at 10 and 16 weeks: insulin, 280+/-82 vs. 914+/-238 pmol/l (120 min, at 16 weeks; P<0.05); glucose, 44.6+/-2.4 vs. 35.2+/-2.6 mmol/l (120 min, at 16 weeks; P<0.05). Thus, our present observations demonstrate the potential usefulness of probucol for treatment of type 2 diabetes.

A paired homeodomain transcription factor, PAX6, is a well-known regulator of eye development, and its heterozygous mutations in humans cause congenital eye anomalies such as aniridia. Because it was recently shown that PAX6 also plays an indispensable role in islet cell development, a PAX6 gene mutation in humans may lead to a defect of the endocrine pancreas. Whereas heterozygous mutations in islet-cell transcription factors such as IPF1/IDX-1/STF-1/PDX-1 and NEUROD1/BETA2 serve as a genetic cause of diabetes or glucose intolerance, we investigated the possibility of PAX6 gene mutations being a genetic factor common to aniridia and diabetes. In five aniridia and one Peters' anomaly patients, all of the coding exons and their flanking exon-intron junctions of the PAX6 gene were surveyed for mutations. The results of direct DNA sequencing revealed three different mutations in four aniridia patients: one previously reported type of mutation and two unreported types. In agreement with polypeptide truncation and a lack of the carboxyl-terminal transactivation domain in all of the mutated PAX6 proteins, no transcriptional activity was found in the reporter gene analyses. Oral glucose tolerance tests revealed that all of the patients with a PAX6 gene mutation had glucose intolerance characterized by impaired insulin secretion. Although we did not detect a mutation within the characterized portion of the PAX6 gene in one of the five aniridia patients, diabetes was cosegregated with aniridia in her family, and a single nucleotide polymorphism in intron 9 of the PAX6 gene was correlated with the disorders, suggesting that a mutation, possibly located in an uncharacterized portion of the PAX6 gene, can explain both diabetes and aniridia in this family. In contrast, the patient with Peters' anomaly, for which a PAX6 gene mutation is a relatively rare cause, showed normal glucose tolerance (NGT) and did not show a Pax6 gene mutation. Taken together, our present observations suggest that heterozygous mutations in the PAX6 gene can induce eye anomaly and glucose intolerance in individuals harboring these mutations.