Michiaki Fukui

Supplementation of hydrogen-rich water improves lipid and glucose metabolism in patients with type 2 diabetes or impaired glucose tolerance.

Oxidative stress is recognized widely as being associated with various disorders including diabetes, hypertension, and atherosclerosis. It is well established that hydrogen has a reducing action. We therefore investigated the effects of hydrogen-rich water intake on lipid and glucose metabolism in patients with either type 2 diabetes mellitus (T2DM) or impaired glucose tolerance (IGT). We performed a randomized, double-blind, placebo-controlled, crossover study in 30 patients with T2DM controlled by diet and exercise therapy and 6 patients with IGT. The patients consumed either 900 mL/d of hydrogen-rich pure water or 900 mL of placebo pure water for 8 weeks, with a 12-week washout period. Several biomarkers of oxidative stress, insulin resistance, and glucose metabolism, assessed by an oral glucose tolerance test, were evaluated at baseline and at 8 weeks. Intake of hydrogen-rich water was associated with significant decreases in the levels of modified low-density lipoprotein (LDL) cholesterol (ie, modifications that increase the net negative charge of LDL), small dense LDL, and urinary 8-isoprostanes by 15.5% (P < .01), 5.7% (P < .05), and 6.6% (P < .05), respectively. Hydrogen-rich water intake was also associated with a trend of decreased serum concentrations of oxidized LDL and free fatty acids, and increased plasma levels of adiponectin and extracellular-superoxide dismutase. In 4 of 6 patients with IGT, intake of hydrogen-rich water normalized the oral glucose tolerance test. In conclusion, these results suggest that supplementation with hydrogen-rich water may have a beneficial role in prevention of T2DM and insulin resistance.

Hydrogen-rich pure water prevents superoxide formation in brain slices of vitamin C-depleted SMP30/GNL knockout mice.

Hydrogen is an established anti-oxidant that prevents acute oxidative stress. To clarify the mechanism of hydrogens effect in the brain, we administered hydrogen-rich pure water (H(2)) to senescence marker protein-30 (SMP30)/gluconolactonase (GNL) knockout (KO) mice, which cannot synthesize vitamin C (VC), also a well-known anti-oxidant. These KO mice were divided into three groups; recipients of H(2), VC, or pure water (H(2)O), administered for 33 days. VC levels in H(2) and H(2)O groups were <6% of those in the VC group. Subsequently, superoxide formation during hypoxia-reoxygenation treatment of brain slices from these groups was estimated by a real-time biography imaging system, which models living brain tissues, with Lucigenin used as chemiluminescence probe for superoxide. A significant 27.2% less superoxide formed in the H(2) group subjected to ischemia-reperfusion than in the H(2)O group. Thus hydrogen-rich pure water acts as an anti-oxidant in the brain slices and prevents superoxide formation.

Relationship between serum bilirubin and albuminuria in patients with type 2 diabetes

Previous studies showed that low serum bilirubin concentrations are associated with increased risk of cardiovascular disease. To explore this further, we evaluated the relationships between serum bilirubin concentrations and the degree of urinary albumin excretion and other markers of subclinical atherosclerosis in 633 consecutive patients with type 2 diabetes. Multiple regression analysis showed that the serum bilirubin concentration was an independent determinant of and had a significant inverse correlation to the log urinary albumin excretion. Serum bilirubin concentrations were significantly lower in patients with than in those without cardiovascular disease. A significant inverse correlation was found between the serum bilirubin concentration and pulse wave velocity, while a significant positive correlation was found to the ankle-brachial index in a subgroup of 386 patients. Our study shows that the serum bilirubin level is associated with microalbuminuria and subclinical atherosclerosis in patients with type 2 diabetes.

Serum uric acid is associated with microalbuminuria and subclinical atherosclerosis in men with type 2 diabetes mellitus

Hyperuricemia has been reported to be associated with increased risk of renal insufficiency as well as cardiovascular events. The aim of this study was to evaluate the relationships between serum uric acid concentration and degree of urinary albumin excretion as well as markers of subclinical atherosclerosis in men with type 2 diabetes mellitus. Serum uric acid concentrations were measured in 343 men with type 2 diabetes mellitus. We then evaluated relationships of serum uric acid concentrations to degree of urinary albumin excretion as well as to major cardiovascular risk factors, including age, blood pressure, serum lipid concentration, and glycemic control (hemoglobin A1c). The relationships between serum uric acid concentration and pulse wave velocity or ankle-brachial index (n=236) and between serum uric acid concentration and carotid intima-media thickness or plaque score (n=125) were investigated additionally in a subgroup of patients. Serum uric acid concentration correlated positively with logarithm of urinary albumin excretion (r=0.302, P<.0001). Positive correlation was found between serum uric acid concentration and intima-media thickness (r=0.233, P=.0087), whereas inverse correlation was found between serum uric acid concentration and ankle-brachial index (r=-0.150, P=.0207). Multiple regression analysis demonstrated that serum uric acid concentration (beta=.281, P<.0001), duration of diabetes (beta=.253, P<.0001), hemoglobin A1c (beta=.166, P=.0034), serum triglyceride concentration (beta=.125, P=.0472), and systolic blood pressure (beta=.275, P=.0013) were independent determinants of logarithm of urinary albumin excretion. In conclusion, serum uric acid concentration is associated with microalbuminuria and subclinical atherosclerosis in men with type 2 diabetes mellitus.

Visit-to-visit variability in systolic blood pressure is correlated with diabetic nephropathy and atherosclerosis in patients with type 2 diabetes

OBJECTIVE Recent studies make remarks on the effect of variability in systolic blood pressure (SBP) on the development of cardiovascular disease. The aim of this study was to investigate the relationship between the variability in SBP and the degree of diabetic nephropathy and atherosclerosis in patients with type 2 diabetes. METHODS We measured SBP in 422 consecutive patients with type 2 diabetes at every visit during a year, and we calculated the coefficient of variation (CV) of SBP. Then, we evaluated relationships of variability of SBP to degree of urinary albumin excretion (UAE), which is a useful marker for cardiovascular disease as well as diabetic nephropathy, ankle-brachial index (ABI) and pulse wave velocity (PWV). RESULTS CV of SBP positively correlated with logUAE (r=0.210, P<0.0001) or PWV (r=0.409, P<0.0001), whereas CV of SBP inversely correlated with ABI (r=-0.098, P=0.0463). Multiple regression analysis demonstrated that CV of SBP independently correlated with logUAE (β=0.149, P=0.0072), PWV (β=0.337, P<0.0001) or ABI (β=-0.162, P=0.0101). CONCLUSIONS Not only average SBP but also variability in SBP is correlated with diabetic nephropathy and atherosclerosis in patients with type 2 diabetes.

Short-term exposure of high glucose concentration induces generation of reactive oxygen species in endothelial cells: implication for the oxidative stress associated with postprandial hyperglycemia

Abstract Recent studies demonstrating a close relationship between postprandial hyperglycemia and the incidence of atherosclerotic cardiovascular disease prompted us to investigate the generation and source of reactive oxygen species (ROS) in endothelial cells stimulated by short-term exposure to a high glucose concentration. In addition, we investigated the effect of insulin on ROS production induced by high glucose concentration. Cultured bovine aortic endothelial cells demonstrated a significant increase in intracellular ROS generation after a 3-h exposure to 25 mM glucose (131.4% versus 5 mM glucose). This increased generation of ROS was suppressed by an inhibitor of NAD(P)H oxidase. Intracellular ROS production in cells exposed to 3 h of high glucose concentration was increased significantly by the presence of a physiological concentration of insulin. However, after a 1-h exposure to high glucose levels, ROS generation in cells incubated with insulin was only about 80% of that measured in cells incubated without insulin. The generation of intracellular nitric oxide (NO) resulting from an acute insulin effect may account for this difference. In conclusion, acute hyperglycemia itself may possibly cause endothelial oxidative stress in patients with postprandial hyperglycemia. Endothelial oxidative stress may be determined by the interaction between NO and superoxide generation.

Protective effect of alcohol consumption for fatty liver but not metabolic syndrome.

AIM To investigate the effect of alcohol on the metabolic syndrome (MS) and fatty liver in Japanese men and women. METHODS A cross-sectional study was conducted in a medical health checkup program at a general hospital. This study involved 18 571 Japanese men and women, 18-88 years of age, with a mean body mass index of 22.6 kg/m(2). A standardized questionnaire was administered. The total amount of alcohol consumed per week was calculated, and categorized into four grades. Fatty liver was examined by ultrasound modified criteria of the revised National Cholesterol Education Program Adult Treatment Panel III and the new International Diabetes Federation. RESULTS The prevalence of fatty liver decreased in men and women with light to moderate alcohol consumption, whereas the prevalence of MS was not so changed. The prevalence of fatty liver of any grade in men was lower than that in those with no or minimal alcohol consumption. In women with light to moderate alcohol consumption, prevalence of fatty liver was lower than that in women with no or minimal alcohol consumption. By logistic regression analysis, the odds ratio (OR) for MS in women with light alcohol consumption was decreased to < 1.0, but this change was not clear in men. The OR for fatty liver was clearly < 1.0 in men with any level of alcohol consumption and in women with light to moderate consumption. CONCLUSION Light to moderate alcohol consumption has a favorable effect for fatty liver, but not for MS in Japanese men and women.

Low serum bilirubin concentration is associated with coronary artery calcification (CAC).

BACKGROUND Bilirubin is a potent antioxidant and previous studies have reported the relationship between low serum bilirubin concentration and atherosclerosis. The purpose of this study was to assess the correlation between serum bilirubin concentration and coronary artery calcification (CAC). METHODS This study consisted of 637 participants and we evaluated the relationship between CAC score determined by multislice computed tomography and serum bilirubin concentration. RESULTS An inverse correlation was found between serum bilirubin concentration and log(CAC+1) (r=-0.361, P<0.0001). Multiple regression analysis also demonstrated that age (beta=0.261, P=0.0125), systolic blood pressure (beta=0.153, P=0.0237), uric acid (beta=0.126, P=0.0441), estimated glomerular filtration rate (beta=-0.139, P=0.0416) and serum bilirubin concentration (beta=-0.281, P<0.0001) were independent determinants of log(CAC+1). An increment of 1 micromol/L in serum bilirubin concentration was associated with 14% decrease in the odds for CAC score > or =400 after adjustment for several risk factors. Both age and SBP were also positively associated with CAC score > or =400, but the odds ratio for CAC score > or =400 was greater for every 1 micromol/L increment in serum bilirubin concentration than for every 1-year increment in age and 1-mmHg increment in SBP. CONCLUSIONS Low serum bilirubin concentration is associated with coronary artery calcification. Serum bilirubin concentration can be measured easily in the clinical laboratory and applied in medical practice, and low serum bilirubin concentration would be useful as a provisional new risk factor of CAC.

Increased serum resistin levels in patients with type 2 diabetes are not linked with markers of insulin resistance and adiposity.

The role of resistin in human biology remains uncertain. We measured serum resistin levels in Japanese patients with (n=111) and without (n=98) type 2 diabetes mellitus and investigated the significance of this hormone in the pathophysiology of diabetes. The levels of serum adiponectin and leptin were also measured. Resistin levels were increased significantly in patients with type 2 diabetes compared with non-diabetic subjects (24.7±2.6 vs. 15.0±1.2 ng/ml, p=0.0013). However, there was no correlation in either patient group between serum resistin levels and markers of insulin resistance, obesity or hyperlipidaemia. These results were in direct contrast to the data of leptin or adiponectin, both of which were closely related to these clinical markers of diabetes. Multivariate regression analysis on the combined data of the two groups demonstrated that the presence of diabetes and HDL cholesterol levels were significant predictors of serum resistin levels (diabetes: β=0.159, p=0.035; HDL: β=-0.172, p=0.039). No correlation was observed between C-reactive protein and resistin adjusted for BMI. Taken together, these findings demonstrate that serum resistin levels are increased in patients with type 2 diabetes, but this increase is not linked to markers of insulin resistance or adiposity. Further studies are necessary to elucidate the significance of serum resistin concentration in human pathophysiology.

Induction of aldose reductase in cultured human microvascular endothelial cells by advanced glycation end products.

Accelerated formation and accumulation of advanced glycation end products, as well as increased flux of glucose through polyol pathway, have been implicated in the pathogenesis of diabetic vascular complications. We investigated effects of advanced glycation end products on the levels of aldose reductase mRNA, protein, and activity in human microvascular endothelial cells. When endothelial cells were cultured with highly glycated bovine serum albumin, aldose reductase mRNA in endothelial cells demonstrated concentration-dependent elevation. The increase in aldose reductase mRNA was accompanied by elevated protein expression and enzyme activity. Significant increase in the enzyme expression was also observed when endothelial cells were cultured with serum obtained from diabetic patients with end-stage renal disease. Pretreatment of the endothelial cells with probucol or vitamin E prevented the advanced glycation end products-induced increases in aldose reductase mRNA and protein. Electrophoretic mobility shift assays using the nuclear extracts of the endothelial cells treated with advanced glycation end products showed enhancement of specific DNA binding activity for AP-1 consensus sequence. These results indicate that accelerated formation of advanced glycation end products in vivo may elicit activation of the polyol pathway, possibly via augmented oxidative stress, and amplify endothelial cell damage leading to diabetic microvascular dysfunction.