Short-Term Efficacy (at 12 Weeks) and Long-Term Safety (up to 52 Weeks) of Omega-3 Free Fatty Acids (AZD0585) for the Treatment of Japanese Patients With Dyslipidemia　- A Randomized, Double-Blind, Placebo-Controlled, Phase III Study.

BACKGROUND: This study is the first to evaluate the short-term efficacy and long-term safety of AZD0585, a mixture of omega-3 free fatty acids, in Japanese patients with dyslipidemia.Methods and Results:In this randomized double-blind placebo-controlled Phase III study, 383 patients were randomized to 2 g AZD0585, 4 g AZD0585, or placebo once daily for 52 weeks. Eligible patients had low-density lipoprotein cholesterol (LDL-C) levels controlled regardless of statin use, and triglyceride levels between 150 and 499 mg/dL. The least-squares (LS) mean percentage changes in triglyceride concentrations from baseline to the 12-week endpoint (mean of measurements at Weeks 10 and 12) in the 2 and 4 g AZD0585 and placebo groups were -15.57%, -21.75%, and 11.15% respectively (P<0.0001 for both AZD0585 doses vs. placebo). No clinically significant changes from baseline to the 12-week endpoint in total cholesterol, LDL-C, and LDL-C/apolipoprotein (Apo) B were found with AZD0585. High-density lipoprotein cholesterol (HDL-C) was slightly increased and very low-density lipoprotein cholesterol, non-HDL-C, ApoC-II, and ApoC-III were decreased with AZD0585 compared with placebo at the 12-week endpoint. Lipid profiles up to Week 52 were consistent with those up to the 12-week endpoint. No clinically important safety concerns were raised. CONCLUSIONS: AZD0585 significantly decreased serum triglyceride levels compared with placebo at the 12-week endpoint and was generally safe and well tolerated in Japanese patients with dyslipidemia.

Possible novel therapy for diabetes with cell-permeable JNK-inhibitory peptide.

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.

Vinegar intake enhances flow-mediated vasodilatation via upregulation of endothelial nitric oxide synthase activity.

This study examined the effect of acetate on endothelial nitric oxide synthase (eNOS) in human umbilical vein endothelial cells (HUVECs) by immunoblotting assay and the ability of acetic acid to upregulate flow-mediated vasodilatation in humans. In HUVECs, acetate induced a biphasic increase in the phosphorylated form of eNOS. The amount of phosphorylated eNOS was significantly increased by exposure to 200 mumol/l acetate for 20 min (early phase) and for 4 h (late phase). The inhibitors of cAMP-dependent protein kinase (PKA) and AMP-activated protein kinase (AMPK) blocked acetate-induced eNOS phosphorylation in the early and the late phase respectively. Furthermore, in postmenopausal women, maximum forearm blood flow (FBF) in response to shear stress increased in the vinegar (acetic acid) administered group compared to the placebo group. These results suggest that acetic acid-induced eNOS phosphorylation contributes to upregulation of flow-mediated vasodilatation in humans.

Mental and physical fatigue-related biochemical alterations.

OBJECTIVE: To confirm fatigue-related biochemical alterations, we measured various parameters just before and after relaxation and fatigue-inducing mental or physical sessions. METHODS: Fifty-four healthy volunteers were randomized to perform relaxation and fatigue-inducing mental and physical sessions for 4 h in a double-blind, three-crossover design. Before and after each session, subjects were asked to rate their subjective sensations of fatigue, and blood, saliva, and urine samples were taken. RESULTS: After the fatigue-inducing mental and physical sessions, subjective scores of fatigue were increased. After the fatigue-inducing mental session, the vanillylmandelic acid level in urine was higher and plasma valine level was lower than after the relaxation session. In contrast, after the fatigue-inducing physical session, serum citric acid, triacylglycerol, free fatty acid, ketone bodies, total carnitine, acylcarnitine, uric acid, creatine kinase, aspartate aminotransferase, lactate dehydrogenase, cortisol, dehydroepiandrosterone, dehydroepiandrosterone sulfate, plasma branched-chain amino acids, transforming growth factor-beta1 and -beta2, white blood cell and neutrophil counts, saliva cortisol and amylase, and urine vanillylmandelic acid levels were higher and serum free carnitine and plasma total amino acids and alanine levels were lower than those after the relaxation session. CONCLUSION: Some mental or physical fatigue-related biochemical changes were determined. Various biochemical alterations reflecting homeostatic perturbation and its responses might be shown. We believe that our results contribute to clarifying the mechanism of fatigue, developing evaluation methods, and establishing a basis for treatment.

Antifatigue effects of coenzyme Q10 during physical fatigue.

OBJECTIVE: This study examined the effects of coenzyme Q10 administration on physical fatigue. METHODS: In a double-blinded, placebo-controlled, three crossover design, 17 healthy volunteers were randomized to oral coenzyme Q10 (100 or 300 mg/d) or placebo administration for 8 d. As a fatigue-inducing physical task, subjects performed workload trials on a bicycle ergometer at fixed workloads twice for 2 h and then rested for 4 h. During the physical tasks, subjects performed non-workload trials with maximum velocity for 10 s at 30 min (30-min trial) after the start of physical tasks and 30 min before the end of the tasks (210-min trial). RESULTS: The change in maximum velocity from the 30- to the 210-min trial in the 300-mg coenzyme Q10-administered group was higher than that in the placebo group. In addition, subjective fatigue sensation measured on a visual analog scale in the 300-mg coenzyme Q10-administered group after the fatigue-inducing physical task and recovery period was alleviated when compared with that in the placebo group. CONCLUSION: Oral administration of coenzyme Q10 improved subjective fatigue sensation and physical performance during fatigue-inducing workload trials and might prevent unfavorable conditions as a result of physical fatigue.

Effects of oral administration of caffeine and D-ribose on mental fatigue.

OBJECTIVE: We examined the effects of administering two different candidate antifatigue substances, caffeine and D-ribose, on mental fatigue. METHODS: In a double-blinded, placebo-controlled, three-way crossover design, 17 healthy volunteers were randomized to oral caffeine (200 mg/d), D-ribose (2000 mg/d), or placebo for 8 d. As fatigue-inducing mental tasks, subjects performed a 30-min Uchida-Kraepelin psychodiagnostic test and a 30-min advanced trail-making test on four occasions. RESULTS: During the tasks, the task performance of the caffeine group was better than that of the placebo group. However, after the fatigue-inducing tasks, although subjective perception of fatigue, motivation, or sleepiness was not significantly different, plasma branched-chain amino acid levels in the caffeine group were lower than those of the placebo group. Administration of D-ribose had no effect. CONCLUSION: Because plasma branched-chain amino acid levels are decreased by mental fatigue, these results suggest that administration of caffeine improved task performance through the enhancement of central nervous system activity without increasing the sensation of fatigue. However, further decreases in branched-chain amino acid levels indicate that caffeine might promote deeper fatigue than placebo. Unfortunately, research subsequent to our study design has shown that D-ribose dosing higher than we used is needed to see a clinical effect and therefore no conclusions can be made from this study as to the efficacy of D-ribose.

Casein hydrolysate containing the antihypertensive tripeptides Val-Pro-Pro and Ile-Pro-Pro improves vascular endothelial function independent of blood pressure-lowering effects: contribution of the inhibitory action of angiotensin-converting enzyme.

Accumulating evidence shows that deterioration of vascular endothelial function underlies the pathophysiology of cardiovascular diseases following lifestyle-related diseases. Both Val-Pro-Pro (VPP) and Ile-Pro-Pro (IPP), which are tripeptides derived from proteolytic hydrolysate of milk casein, inhibit angiotensin-converting enzyme (ACE), suggesting that both VPP and IPP may improve vascular endothelial function, because many ACE inhibitors are known to improve endothelial function. We investigated the effects of ACE-inhibitory food component in humans with mild hypertension, since there has been no report on such effects. The study was conducted by the placebo-controlled, double-blind crossover method in 25 male subjects with mild hypertension. After casein hydrolysate containing both VPP and IPP were administered for 1 week, reactive hyperemia of the left upper forearm was measured using plethysmography as an index of vascular endothelial function. Since one subject dropped out, we analyzed the data of 24 subjects. The reactive hyperemia of the left upper forearm was produced by a 5 min occlusion using inflation of a cuff. The maximum blood flow during reactive hyperemia was 20.8+/-6.7 mL/min/100 mL tissue in the placebo group, whereas it increased remarkably to 30.0+/-10.4 mL/min/100 mL tissue in the group administered casein hydrolysate containing both VPP and IPP (p<0.001). There was no change in systemic blood pressure, indicating that the improvement of the vascular endothelial function attributable to VPP and IPP is independent of hemodynamic changes. We conclude that casein hydrolysate containing VPP and IPP improves the vascular endothelial dysfunction in subjects with mild hypertension. The continuous intake of VPP and IPP could help to prevent cardiovascular diseases in hypertensive subjects.

Effects of Applephenon and ascorbic acid on physical fatigue.

OBJECTIVE: We examined the effects of Applephenon and ascorbic acid administration on physical fatigue. METHODS: In a double-blinded, placebo-controlled, three-way crossover design, 18 healthy volunteers were randomized to oral Applephenon (1200 mg/d), ascorbic acid (1000 mg/d), or placebo for 8 d. The fatigue-inducing physical task consisted of workload trials on a bicycle ergometer at fixed workloads for 2 h on two occasions. During the test, subjects performed non-workload trials with maximum velocity for 10 s at 30 min (30-min trial) after the start of the test and 30 min before the end of the test (210-min trial). RESULTS: The change in maximum velocity between the 30- and 210-min trials was higher in the group given Applephenon than in the group given placebo; ascorbic acid had no effect. CONCLUSION: These results suggest that Applephenon attenuates physical fatigue, whereas ascorbic acid does not.

Effects of Citric Acid and l-Carnitine on Physical Fatigue.

We examined the effects of citric acid and l-carnitine administration on physical fatigue. In a double-blind, placebo-controlled, 3-way crossover study, 18 healthy volunteers were randomized to oral citric acid (2,700 mg/day), l-carnitine (1,000 mg/day), or placebo for 8 days. The fatigue-inducing physical task consisted of workload trials on a cycle ergometer at fixed workloads for 2 h on 2 occasions. Before the physical load, salivary chromogranin A, measured as a physiological stress marker, was lower in the group given citric acid than in the group given placebo. Also, after the physical load, the subjective feeling of fatigue assessed with a visual analogue scale was lower in the citric acid group than in the placebo group. In contrast, l-carnitine had no effect on chromogranin A or subjective fatigue. These results suggest that citric acid reduces physiological stress and attenuates physical fatigue, whereas l-carnitine does not.

Plasma aldosterone level within the normal range is less associated with cardiovascular and cerebrovascular risk in primary aldosteronism.

BACKGROUND: Previous studies showed higher risk of cardiovascular and cerebrovascular (CCV) events in primary aldosteronism compared with essential hypertension, but the patients of these studies were limited to primary aldosteronism patients with high plasma aldosterone concentration (PAC). The introduction of the aldosterone-renin ratio as the screening test for primary aldosteronism led to the recognition of primary aldosteronism patients with normal PAC (nPA). However, there is no information on the risk of primary aldosteronism including nPA. METHOD: In this retrospectively and cross-sectional study, the clinical features and CCV event risk of primary aldosteronism at diagnosis including nPA were investigated and compared with essential hypertension. The study included 292 consecutive primary aldosteronism patients and 498 essential hypertension outpatients. All primary aldosteronism patients were diagnosed by autonomous aldosterone secretion using confirmatory tests, and then divided into nPA (n = 130) and primary aldosteronism patients with high PAC (hPA: n = 162) using a PAC cutoff level of less than 443 pmol/l (16 ng/dl), representing the normal upper limit of PAC. RESULTS: nPA patients were significantly older at diagnosis of primary aldosteronism and at onset of hypertension compared with hPA patients. They had milder hypokalemia and easier-to-control blood pressure. The results suggested that nPA could be considered a mild type of primary aldosteronism but not an early-stage hPA. Moreover, the risk of all CCV events in nPA was significantly lower than that in hPA (odds ratio 0.42, 95% confidence interval 0.18-0.90, P < 0.05) and not significantly higher than that in essential hypertension (odds ratio 0.95, 95% confidence interval 0.43-1.94, P = 0.899). CONCLUSION: This study suggests that aggressive diagnostic workout for nPA is less effective to prevent CCV events.

PDX-1 induces differentiation of intestinal epithelioid IEC-6 into insulin-producing cells.

A homeodomain containing transcription factor PDX-1 can induce beta-cell-specific gene expressions in some non-beta-cells and may therefore be useful for future diabetes gene/cell therapy. Among the potential target organs or tissues for transcription factor-mediated induction of beta-cell-like differentiation are the intestinal epithelial cells. They have certain merits over other tissues and organs in terms of accessibility for gene delivery and of similarity in developmental background to the pancreatic primordium. In this study, we used an intestinal epithelium-derived cell line, IEC-6 cells, and investigated the possible effects of PDX-1 expression in those cells. By exogenous expression of the PDX-1 gene, IEC-6 cells started expressing multiple beta-cell-specific genes such as amylin, glucokinase, and Nkx6.1, which were not found in the original IEC-6 cells. Insulin gene expression, which was missing initially even in the PDX-1-transfected IEC-6 cells, became detectable when the cells were transplanted under the renal capsule of a rat. When the PDX-1(+) IEC-6 cells were kept in vitro, treatment with betacellulin could also confer insulin gene expression to them. Although insulin secretory granules became visible by electron microscopy, they were secreted regardless of glucose concentration. The in vivo or in vitro inductions of the insulin gene expression were not observed in the PDX-1(-) IEC-6 cells. Thus, our present observations demonstrate the potency of intestinal epithelial cells as a tool for diabetes gene/cell therapy and provide further support for the potency of PDX-1 in driving beta-cell-like differentiation in non-beta-cells.

Oxidative stress induces nucleo-cytoplasmic translocation of pancreatic transcription factor PDX-1 through activation of c-Jun NH(2)-terminal kinase.

Oxidative stress is induced in pancreatic beta-cells under diabetic conditions and causes beta-cell dysfunction. Antioxidant treatment of diabetic animals leads to recovery of insulin biosynthesis and increases the expression of its controlling transcription factor, pancreatic duodenal homeobox-1 (PDX-1), in pancreatic beta-cells. Here, we show that PDX-1 is translocated from the nuclei to the cytoplasm of pancreatic beta-cells in response to oxidative stress. When oxidative stress was charged upon beta-cell-derived HIT-T15 cells, both endogenous PDX-1 and exogenously introduced green fluorescent protein-tagged PDX-1 moved from the nuclei to the cytoplasm. The addition of a dominant negative form of c-Jun NH(2)-terminal kinase (JNK) inhibited oxidative stress-induced PDX-1 translocation, suggesting an essential role of JNK in mediating this phenomenon. Whereas the nuclear localization signal (NLS) in PDX-1 was not affected by oxidative stress, leptomycin B, a specific inhibitor of the classical leucine-rich nuclear export signal (NES), inhibited nucleo-cytoplasmic translocation of PDX-1 induced by oxidative stress. Moreover, we identified an NES at position 82-94 of the mouse PDX-1 protein. Thus, our present results revealed a novel mechanism that negatively regulates PDX-1 function. The identification of the NES, which overrides the function of the NLS in an oxidative stress-responsive, JNK-dependent manner, supports the complicated regulation of PDX-1 function in vivo and may further the understanding of beta-cell pathophysiology in diabetes.

PAX6 mutation as a genetic factor common to aniridia and glucose intolerance.

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.

alpha-Glucosidase inhibitor reduces the progression of carotid intima-media thickness.

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.

Effect of casein hydrolysate, prepared with protease derived from Aspergillus oryzae, on subjects with high-normal blood pressure or mild hypertension.

Casein hydrolysate, prepared with Aspergillus oryzae protease, contains angiotensin I-converting enzyme inhibitory peptides, such as Val-Pro-Pro and Ile-Pro-Pro. We conducted a randomized, double-blind, placebo-controlled study to evaluate the effect of casein hydrolysate on the blood pressure of 144 subjects with high-normal blood pressure (n = 104) and mild hypertension (n = 40). Subjects were randomly assigned to two groups for a 12-week intake period. In the test group, both systolic (SBP) and diastolic (DBP) blood pressure decreased significantly compared with the placebo group: SBP/DBP significantly decreased from 138.2 +/- 6.5/84.4 +/- 5.3 mm Hg at week 0 to 132.3 +/- 7.3 (P < .001)/81.2 +/- 4.8 mm Hg (P < .001) at week 12. In the stratified analysis, the test product showed an antihypertensive effect in both the subject group with high-normal blood pressure and that with mild hypertension. No side effect was observed in any subjects in this study. These results demonstrate that the casein hydrolysate, prepared with A. oryzae protease, produced a significant reduction in blood pressure in a population of subjects with high-normal blood pressure or mild hypertension without an adverse event.

Association of NAD(P)H oxidase p22 phox gene variation with advanced carotid atherosclerosis in Japanese type 2 diabetes.

OBJECTIVE: To evaluate the association between the C242T polymorphism of the p22 phox gene, an essential component of NAD(P)H oxidase in the vasculature, with intima-media thickness (IMT) of the carotid artery and risk factors for atherosclerosis in type 2 diabetic subjects. RESEARCH DESIGN AND METHODS: C242T polymorphism of the p22 phox gene was detected by polymerase chain reaction-restriction fragment-length polymorphism in 200 Japanese type 2 diabetic subjects and 215 nondiabetic subjects. We examined the association with this mutation and carotid atherosclerosis as well as the patients' clinical characteristics and the level of 8-hydroxy-2'deoxyguanosine (8-OHdG) as an index of oxidative DNA damage. RESULTS: The diabetic subjects with the TC+TT genotypes displayed a significantly lower average IMT (1.13 +/- 0.31 vs. 1.31 +/- 0.34 mm; P = 0.0099) and a not significantly lower serum 8-OHdG level than those with the CC genotype, despite no difference in the risk factors. Stepwise multiple regression analysis showed that the risk factors for increased IMT in the diabetic subjects were systolic blood pressure (P = 0.0042) and p22 phox CC genotype (P = 0.0151). In nondiabetic subjects, the average IMT of the TC+TT group was not different from that of the CC group (0.85 +/- 0.14 vs. 0.94 +/- 0.30 mm, P = 0.417). Fasting plasma insulin concentration (41.4 +/- 15.6 vs. 64.2 +/- 59.4 pmol/l, P = 0.0098) and insulin resistance index of homeostasis model assessment (HOMA-R) (1.58 +/- 0.66 vs. 2.60 +/- 2.56, P = 0.0066) were significantly lower in the TC+TT group than in the CC group. CONCLUSIONS: These results show that the C242T mutation in the p22 phox gene is associated with progression of asymptomatic atherosclerosis in the subjects with type 2 diabetes and is also associated with insulin resistance in nondiabetic subjects.

Elevated C-reactive protein associates with early-stage carotid atherosclerosis in young subjects with type 1 diabetes.

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.

Role of oxidative stress in pancreatic beta-cell dysfunction.

Oxidative stress is produced under diabetic conditions and is likely involved in progression of pancreatic beta-cell dysfunction found in diabetes. Possibly caused by low levels of antioxidant enzyme expressions, pancreatic beta-cells are vulnerable to oxidative stress. When beta-cell-derived HIT-T15 cells or isolated rat islets were exposed to oxidative stress, insulin gene expression was markedly decreased. To investigate the significance of oxidative stress in the progression of pancreatic beta-cell dysfunction in type 2 diabetes, we evaluated the effects of antioxidants in diabetic C57BL/KsJ-db/db mice. According to an intraperitoneal glucose tolerance test, the treatment with antioxidants retained glucose-stimulated insulin secretion and moderately decreased blood glucose levels. Histological analyses of the pancreata revealed that the beta-cell mass was significantly larger in the mice treated with the antioxidants, and the antioxidant treatment suppressed apoptosis in beta-cells without changing the rate of beta-cell proliferation. The antioxidant treatment also preserved the amounts of insulin content and insulin mRNA, making the extent of insulin degranulation less evident. As possible mechanism underlying the phenomena, expression of pancreatic and duodenal homeobox factor-1 (also known as IDX-1/STF-1/IPF1), an important transcription factor for the insulin gene, was more clearly visible in the nuclei of islet cells after the antioxidant treatment. Under diabetic conditions, JNK is activated by oxidative stress and involved in the suppression of insulin gene expression. This JNK effect appears to be mediated in part by nucleocytoplasmic translocation of PDX-1, which is also downstream of JNK activation. Taken together, oxidative stress and consequent activation of the JNK pathway are involved in progression of beta-cell dysfunction found in diabetes. Antioxidants may serve as a novel mechanism-based therapy for type 2 diabetes.

Brain-derived neurotrophic factor ameliorates hepatic insulin resistance in Zucker fatty rats.

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.

NAD (P) H oxidase p22 phox C242T polymorphism affects LDL particle size and insulin resistance in Japanese subjects.

Elevated cardiovascular risk is associated with an increased number of small, dense low-density lipoprotein (LDL) particles, which exhibit increased susceptibility to lipid oxidation, however, the mechanism determining LDL particle size has never been fully elucidated. We have examined the association between the C242T polymorphism of the p22 phox gene, which is a small subunit of vascular NAD(P)H oxidase, and both LDL particle size and clinical characteristics in 260 healthy subjects. Peak LDL particle diameter (LDL-PPD) was measured by continuous disk polyacrylamide gel electrophoresis. Twenty-one of the 217 subjects with the CC genotype showed pattern B (median LDL-PPD under 25.5 nm), whereas, none of the 43 subjects with TC + TT genotypes showed pattern B. The pattern B fraction was significantly larger in the CC group than in the TC + TT group (p = 0.030). The subjects with the CC genotype also showed a significantly higher fasting glucose level, plasma insulin level, and insulin resistance index of homeostasis model assessment (HOMA-R) than those with the TC + TT genotype. Our data demonstrate that variation in the small NAD(P)H oxidase subunit p22 phox gene substantially influences LDL particle size and may also reflect differences in the insulin sensitivity of non-diabetic subjects.