Evidence for Indoxyl Sulfate as an Inducer of Oxidative Stress in Patients With Diabetes.

BACKGROUND/AIM: Indoxyl sulfate is a metabolite of tryptophan and its urinary level reflects the status of bacterial flora in the intestine. Indoxyl sulfate possesses prooxidant properties and is implicated in various diseases including chronic kidney disease and cardiovascular diseases. However, the relation of urinary indoxyl sulfate to oxidative stress is not known. PATIENTS AND METHODS: The association of urinary indoxyl sulfate levels with urinary levels of oxidative stress markers, 15-isoprostane F2t and pteridine derivatives, was investigated in 255 patients with type 2 diabetes. Indoxyl sulfate and pteridine derivatives were measured by using spectrofluorometry. RESULTS: Urinary levels of indoxyl sulfate, pteridines, and 15-isoprostane F2t showed a normal distribution after logarithmic transformation but not before it, and they were thus used for parametric analysis after logarithmic transformation. Urinary indoxyl sulfate levels were significantly correlated (p<0.01) with urinary 15-isoprostane F2t and pteridine levels [Pearson's correlation coefficients: 0.503 (15-isoprostane F2t) and 0.562 (pteridines)]. These associations were also found in multivariable analysis after adjusting for age, sex, insulin therapy for diabetes, body mass index, mean arterial pressure, hemoglobin A1c, estimated glomerular filtration rate, urinary albumin, and histories of smoking and alcohol drinking. CONCLUSION: Urinary indoxyl sulfate levels showed associations with urinary levels of oxidative stress markers, and the associations were independent of age, sex, insulin therapy for diabetes, body mass index, blood pressure, glycemic status, renal function, smoking, and alcohol drinking. Indoxyl sulfate appears to be an important determinant of redox balance in patients with diabetes.

Data on urinary pteridines as a discriminator of atherosclerotic risk in patients with diabetes.

Presented here are the supplemental data of the research article "Urinary pteridines as a discriminator of atherosclerotic risk in patients with diabetes" [1]. These data provide the first information on variables that affect urinary levels of pteridines (oxidized-form pteridine derivatives) in patients with diabetes mellitus. In linear regression analysis, gender (women vs. men), current history of smoking and urinary albumin showed significant positive correlations with pteridines, while there were significant inverse correlations of pteridines with a history of alcohol drinking and body mass index. The above associations were confirmed by using analysis of covariance and logistic regression analysis. Among the eight variables (age, gender, medication therapy for diabetes, smoking, alcohol drinking, body mass index, hemoglobin A1c and urinary albumin) tested, smoking showed the strongest association with urinary pteridines.

Urinary pteridines as a discriminator of atherosclerotic risk in patients with diabetes.

Background and aims: We have recently proposed urinary pteridine level as a useful biomarker of oxidative stress in a general population. However, the significance of urinary pteridines in patients with diabetes is unknown. Methods: The relationships of the level of urinary pteridine derivatives with d-dimer, ankle-brachial pressure index (ABI), and known cardiovascular risk factors were investigated in patients with type 2 diabetes. Results: Urinary pteridine level showed significant positive correlations with urinary15-isoprostane F2t, female gender, history of smoking and d-dimer and significant inverse correlations with history of alcohol drinking, body mass index (BMI) and ABI. ABI was significantly lower and d-dimer was significantly higher in the highest tertile group of pteridines than in the lowest tertile group. The odds ratios of the highest vs. lowest tertiles for low ABI and high d-dimer were significantly higher than the reference level. The above relationships of urinary pteridines with ABI and d-dimer were not altered when age, gender, BMI, hemoglobin A1c and history of alcohol drinking were used as explanatory variables in multivariable analyses. History of smoking confounded the relation of pteridines with ABI but not that with d-dimer. However, in logistic regression analysis, the association between pteridines and ABI remained significant with adjustment for history of smoking. Conclusion: Urinary pteridine level was associated with d-dimer and ABI, which reflect blood coagulability and arterial flow to the lower extremities, respectively, and is thus thought to be a useful discriminator of thromboatherosclerotic risk in patients with diabetes.

Inverse association between habitual alcohol drinking and d-dimer in patients with type 2 diabetes mellitus.

Alcohol is known to inhibit blood coagulation. Patients with diabetes mellitus are prone to show hypercoagulability. However, it remains to be clarified whether and how habitual alcohol drinking affects coagulability in patients with diabetes. The purpose of this study was to determine the relationship between alcohol intake and d-dimer, a sensitive marker of blood coagulation, in patients with diabetes. We investigated the relationship between alcohol intake and d-dimer in plasma of 269 patients with type 2 diabetes by using analysis of covariance and logistic regression analysis after adjustment for age, gender, body mass index, hemoglobin A1c, and histories of smoking and anti-coagulation therapy. Log-transformed d-dimer and HDL cholesterol were significantly lower and higher, respectively, in regular drinkers than in nondrinkers, while there were no significant differences in log-transformed d-dimer and HDL cholesterol in occasional drinkers and nondrinkers. Odds ratios of regular drinkers vs. nondrinkers for high d-dimer (0.46 [0.21-0.98]) and low HDL cholesterol (0.20 [0.08-0.50]) were significantly lower than the reference level, while the odds ratios of occasional drinkers for high d-dimer (1.24 [0.41-3.73]) and low HDL cholesterol (0.43 [0.15-1.25]) were not significantly different from the reference level. HDL cholesterol showed a significant inverse correlation with log-transformed d-dimer both in overall subjects and in nondrinkers. Regular drinking, but not occasional drinking, was associated with lower d-dimer levels, suggesting that habitual alcohol drinking suppresses hypercoagulability in patients with diabetes. There is an alcohol intake-independent inverse association between HDL cholesterol and d-dimer.

Relationships of oxidized HDL with blood coagulation and fibrinolysis in patients with type 2 diabetes mellitus.

Although oxidization of LDL is known to be a crucial step for atherosclerotic progression, the significance of oxidized HDL remains to be clarified. The purpose of this study was to determine the relationships of oxidized HDL with blood coagulation and fibrinolysis in patients with diabetes. The subjects were outpatients with type 2 diabetes (n = 163; median hemoglobin A1c, 6.9%). Activities of blood coagulation and fibrinolysis were evaluated by levels of thrombin-anti-thrombin complex (TAT) and plasmin-α2 plasmin inhibitor complex (PIC), respectively. Relationships of oxidized HDL with TAT and PIC were investigated by using linear regression analysis and logistic regression analysis. Oxidized HDL showed a significant inverse correlation with TAT and a marginally significant correlation with PIC (Spearman's rank correlation coefficient: TAT, - 0.205 [p < 0.01]; PIC, - 0.135 [p = 0.087]). Prevalence of high TAT was significantly lower in the 3rd tertile group for oxidized HDL than in its 1st tertile (20.4 vs. 5.6%, p < 0.05), and prevalence of high PIC was marginally significantly lower in the 3rd tertile group for oxidized HDL than in its 1st tertile (40.7 vs. 24.1%, p = 0.099). In multivariate logistic regression analysis using age, gender, smoking, alcohol drinking, BMI, hemoglobin A1c, therapy for dyslipidemia, therapy for diabetes and anti-coagulation therapy as explanatory variables, odds ratios for high TAT and high PIC in the 3rd tertile group for oxidized HDL versus its 1st tertile group were significantly lower than the reference level of 1.00 (high TAT: 0.19 [0.04-0.99], p < 0.05; high PIC: 0.33 [0.12-0.95], p < 0.05). The frequency of high TAT or high PIC was lower in the higher tertile group for oxidized HDL than in its lower tertile group. Thus, oxidized HDL is thought to be inversely associated with both blood coagulation and fibrinolysis in patients with type 2 diabetes.

Detection of Subclinical Peripheral Artery Ischemia in Healthy Male Smokers by an Ankle-Brachial Index After Exercise: Sasayama Study.

We investigated the relationship between smoking and the risk of nonnormal (≤0.99) ankle-brachial index (ABI) at rest and after ankle plantar flexion exercise in healthy male community dwellers. A cross-sectional study was performed including 228 Japanese men aged 40 to 64 years without a history of cardiovascular diseases. Participants were classified as never, ex-, and current smokers. We estimated the multivariate-adjusted odds ratios (ORs) for nonnormal ABI of ex- and current smokers in relation to never smokers after adjusting for age and other confounding factors. At rest, the prevalence of nonnormal ABI was not significantly different by smoking status. After exercise, the prevalence of nonnormal ABI increased from 1.8% to 11.5% in ex-smokers and from 3.8% to 17.0% in current smokers, while the prevalence did not significantly change in never smokers. The multivariate-adjusted OR for nonnormal ABI after ankle plantar flexion exercise, in relation to never smokers, was 3.85 (95% confidence interval [CI]: 0.79-18.9) for ex-smokers and 6.97 (95% CI: 1.32-36.7) for current smokers. Our results suggest that ABI after ankle plantar flexion exercise is useful for early detection of subclinical peripheral artery ischemia in male smokers without typical symptoms.

Cysteinylated transthyretin as a discriminator of cardiovascular risk in patients with diabetes mellitus.

BACKGROUND: The cysteine residue on transthyretin (TTR) is susceptible to be oxidized, and serum cysteinylated TTR (Cys-TTR) level is thought to reflect oxidative stress. The purpose of this study was to elucidate the relationship between Cys-TTR and arterial stiffness, a known predictor of cardiovascular disease, in patients with type 2 diabetes. METHODS: The subjects were 105 male outpatients with type 2 diabetes. Arterial stiffness was evaluated by measuring cardio-ankle vascular index (CAVI). The relationship between CAVI and ratio of Cys-TTR to total TTR (Cys-TTR ratio) was analyzed. RESULTS: Cys-TTR ratio was significantly correlated with CAVI (Pearson's correlation coefficient: 0.316, p<0.01), and CAVI was significantly higher in the 3rd tertile group for Cys-TTR ratio than in its 1st tertile group. These relationships were also significant after adjusting for age, smoking, alcohol drinking, body mass index, mean arterial pressure, hemoglobin A1c, LDL cholesterol-to-HDL cholesterol ratio and eGFR. Prevalence of high CAVI (≥10.0) was significantly higher in the 3rd tertile for Cys-TTR ratio than in its 1st tertile and tended to be higher with an increase in tertile (28.6% in the 1st tertile, 42.9% in the 2nd tertile and 60.0% in the 3rd tertile). Odds ratio (OR) for high CAVI of the 3rd vs. 1st tertile groups for Cys-TTR ratio was significantly higher than the reference level of 1.00 both before and after adjustment for the above cardiovascular risk factors (crude OR, 3.75 [1.38-10.17]; adjusted OR, 5.09 [1.39-18.64]). CONCLUSIONS: Cys-TTR ratio is associated with arterial stiffness in patients with diabetes and is proposed as a new discriminator of cardiovascular risk.

Association between serum long-chain n-3 and n-6 polyunsaturated fatty acid profiles and glomerular filtration rate assessed by serum creatinine and cystatin C levels in Japanese community-dwellers.

BACKGROUND: Plasma concentration of n-3 polyunsaturated fatty acids (PUFAs) has been reported to be associated with renal function in Western populations. However, few studies have investigated the association between serum long-chain n-3 and n-6 PUFA profiles and renal function in a Japanese population with high marine-derived long-chain n-3 PUFA intake. METHODS: A cross-sectional study was performed in 549 Japanese rural community-dwellers aged 40 to 64 years. In adjusted analysis of covariance, we assessed the relationship between estimated glomerular filtration rate (eGFR) and tertiles of serum long-chain n-3 and n-6 PUFA profiles ([eicosapentaenoic acid {EPA} + docosahexaenoic acid {DHA}]:arachidonic acid [AA]). GFR was estimated by Japanese specific equations using serum creatinine and cystatin C (eGFRcre and eGFRcys). Using multivariate-adjusted linear regression models, we also assessed the relationships between eGFRs and several n-3 and n-6 PUFAs, which have been suggested to be associated with renal function. RESULTS: In all participants, higher dietary fish intake as assessed by a semi-quantitative questionnaire was associated with higher serum value of (EPA+DHA):AA. Participants in the higher (EPA+DHA):AA tertiles had non-significantly higher eGFRcre and significantly higher eGFRcys (P = 0.016). In addition, eGFRcys in T2+T3 of (EPA+DHA):AA was significantly higher than that in T1 (adjusted mean eGFRcys, T1: 87 ml/min/1.73 m(2), T2+T3: 91 ml/min/1.73 m(2); P < 0.01). Among the PUFAs, only (EPA+DHA) was significantly associated with eGFRcys. CONCLUSIONS: Serum (EPA+DHA):AA, which reflects an individual's fish intake, might be associated with eGFRcys in Japanese community-dwellers.

Hairy cell leukemia accompanied by Evans syndrome.

We report a case of Western type hairy cell leukemia (HCL), a very rare leukemia in Japan. In this malignancy, leukemic cells in a peripheral blood film may be missed due in part to accompanying pancytopenia and in part to loss of typical cytoplasmic projections if prepared in a conventional Japanese way using forced air-drying. Our present patient also had a variety of autoantibodies and the clinical picture was primarily that of Evans syndrome (ES), suggesting disturbed immune responses associated with the HCL. Although HCL accompanied by either AIHA or ITP has been reported, the occurrence of ES in HCL is extremely rare.

Intracellular alkalinization augments capacitative Ca2+ entry in vascular smooth muscle cells.

Agonist-induced Ca2+ influx of vascular smooth muscle cells is thought to be triggered by depletion of intracellular Ca2+ stores. This study investigated the effects of intracellular alkalinization on capacitative Ca2+ entry in A7r5 rat aortic smooth muscle cells. Intracellular alkalinization was induced by NH(4)Cl. Transplasmalemmal Ca2+ influx due to Ca2+ store depletion induced by thapsigargin, which was abolished by pretreatment of the cells with SKF-96365 but not affected by that with verapamil, was significantly increased by pretreatment with NH(4)Cl. Neither 5-hydroxytryptamine-induced inositol monophosphate accumulation nor intracellular Ca2+ release from its stores was affected by NH(4)Cl. These results suggest that intracellular alkalinization acts on the process(es) after depletion of Ca2+ stores and facilitates capacitative Ca2+ entry in vascular smooth muscle cells.