Xanthine Oxidase Activity in Type 2 Diabetes Mellitus Patients with and without Diabetic Peripheral Neuropathy.

This study investigated the relationship between serum xanthine oxidase (XOD) activity and the occurrence of diabetic peripheral neuropathy (DPN) in type 2 diabetes mellitus (T2DM) patients. Serum XOD activity, ischemia-modified albumin (IMA), uric acid (UA), albumin, glycated hemoglobin (HbA1c), advanced glycation end products (AGE), total free thiols, atherogenic index of plasma (AIP), and body mass index (BMI) were measured in 80 T2DM patients (29 with and 51 without DPN), and 30 nondiabetic control subjects. Duration of diabetes, hypertension, medication, and microalbuminuria was recorded. Serum XOD activities in controls, non-DPN, and DPN were 5.7 ± 2.4 U/L, 20.3 ± 8.6 U/L, and 27.5 ± 10.6 U/L (p < 0.01), respectively. XOD activity was directly correlated to IMA, UA, BMI, HbA1c, and AGE, while inversely correlated to serum total free thiols. A multivariable logistic regression model, which included duration of diabetes, hypertension, AIP, HbA1c, UA, and XOD activity, revealed HbA1c [OR = 1.03 (1.00-1.05); p = 0.034] and XOD activity [OR = 1.07 (1.00-1.14); p = 0.036] as independent predictors of DPN. Serum XOD activity was well correlated to several other risk factors. These results indicate the role of XOD in the development of DPN among T2DM patients.

Sequential analysis of oxidative stress markers and vitamin C status in acute bacterial osteomyelitis.

In bacterial bone infections, excessively formed oxidants may result in local and systemic oxidative stress. Vitamin C is the major extracellular nonenzymatic antioxidant, also implicated in bone cells metabolism and viability. The physiological functions of vitamin C largely depend on its redox status. We sequentially assessed oxidative stress markers, hydroperoxides and malondialdehyde (MDA), total antioxidant activity (AOA), total vitamin C, ascorbic acid (Asc), and oxidized/reduced vitamin C ratio in 137 patients with acute osteomyelitis (OM). Compared to 52 healthy controls, in OM group baseline serum hydroperoxides, MDA and oxidized/reduced vitamin C ratio were higher whilst Asc and AOA were lower (P < 0.05, resp.). On the other side, total vitamin C levels in patients and controls were similar (P > 0.05), thereby suggesting a relative rather than absolute vitamin C deficiency in OM. During the follow-up, oxidative stress markers, AOA, and oxidizedreduced vitamin C ratio were gradually returned to normal, while there was no apparent change of total vitamin C concentrations. Persistently high values of oxidized/reduced vitamin C ratio and serum MDA were found in subacute OM. In conclusion, acute OM was associated with enhanced systemic oxidative stress and the shift of vitamin C redox status towards oxidized forms.

Predictive value of serum myeloperoxidase activity for thrombosis of arteriovenous fistulas.

Myeloperoxidase is a proinflammatory protein that appears as a result of increased oxidative stress. It plays an important role in the promotion and progression of atherosclerosis. The aim of this study was to determine the importance of MPO as a predictive parameter for thrombosis of arteriovenous fistula (AVF). The study involved monitoring patients with AVFs for hemodialysis over a period of 2 years. There were 41 patients, 19 (46%) men and 22 (54%) women, with mean age of 65 ± 12.7 years. Routine laboratory analyses were carried out in all respondents, including determination of MPO concentration. Gender, demographic and anthropometrical characteristics, smoking, alcohol consumption, as well as the presence of diabetic nephropathy, as an etiological factor of kidney disease, were recorded. The group of patients who developed initial thrombosis of the AVFs had significantly different values for leukocytes (8.5 ± 3.8 vs. 7.3 ± 2.1, P = 0.024), erythrocytes (2.8 ± 0.27 vs. 3.2 ± 0.65; P = 0.019), hemoglobin (88.5 ± 81 vs. 99.1 ± 6.02; P = 0.041), and myeloperoxidase (19.3 ± 4.67 vs. 11.1 ± 4.43; P = 0.007) when compared with the group without fistula thrombosis. Diabetic nephropathy (P = 0.02) characterized the group of patients with thrombosis of the fistula. Diabetic nephropathy (B = 2.53, P = 0.049) and MPO (B = 0.03, P = 0.029) were statistically significant predictors of fistula thrombosis. In our study, MPO and diabetic nephropathy were predictors of thrombosis of the AVF.

Arteriovenous fistulas and digital hypoperfusion ischemic syndrome in patients on hemodialysis.

AIM: To determine survival parameters as well as characteristics of patients with this syndrome. METHODS: The investigation was conducted over a period of eight years, as a prospective, non-randomized, clinical study which included 204 patients, treated by chronic hemodialysis. Most patients received hemodialysis 12 h per week. As vascular access for hemodialysis all subjects had an arteriovenous fistulae. Based on surveys the respondents were divided into groups of patients with and without digital hypoperfusion ischemic syndrome. Gender, demographic and anthropometric characteristics, together with comorbidity and certain habits, were recorded. During this period 34.8% patients died. RESULTS: Patients with digital hypoperfusion ischemic syndrome were older than those without ischemia (P = 0.01). Hemodialysis treatment lasted significantly longer in the patients with digital hypoperfusion ischemic syndrome (P = 0.02). The incidence of cardiovascular disease (P < 0.001) and diabetes mellitus (P = 0.01), as well as blood flow through the arteriovenous fistula (P = 0.036), were higher in patients with digital hypoperfusion ischemic syndrome. Statistically significant differences also existed in relation to oxygen saturation (P = 0.04). Predictive parameters of survival for patients with digital hypoperfusion ischemic syndrome were: adequacy of hemodialysis (B = -3.604, P < 0.001), hypertension (B = -0.920, P = 0.018), smoking (B = -0.901, P = 0.049), diabetes mellitus (B = 1.227, P = 0.005), erythropoietin therapy (B = 1.274, P = 0.002) and hemodiafiltration (B = -1.242, P = 0.033). Kaplan-Meier survival analysis indicated that subjects with and without digital hypoperfusion ischemic syndrome differed regarding the length of survival (P < 0.001), i.e., patients with confirmed digital hypoperfusion ischemic syndrome died earlier. CONCLUSION: Survival was significantly longer in the patients without digital hypoperfusion ischemic syndrome.

Xanthine oxidase and lens oxidative stress markers in diabetic and senile cataract patients.

Xanthine oxidase (XOD) is a prooxidant enzyme possibly implicated in diabetic lens injury and genesis of senile cataract (SC). We evaluated the impact of diabetes on XOD activity and its relationships with lens oxidative stress markers in patients operated on for SC. Serum and lens XOD activities, lens malondialdehyde (MDA), conjugated dienes, superoxide dismutase (SOD), glutathione peroxidase (GPx) and reduced glutathione (GSH) levels were measured in 62 non-diabetic and 29 diabetic patients operated on for SC. Lens XOD, SOD, GPx and GSH levels were gradually declining, while MDA and serum XOD were increasing with patient's age. Lens XOD activity was positively correlated with conjugated dienes concentration (rho=0.316; p=0.003) while being inversely correlated with age (rho=-0.371; p<0.001), indicating that low ocular expression of XOD could be related to lower intensity of oxidative stress and delayed occurrence of SC. When samples were adjusted for confounding factors, serum XOD (p<0.001), lens XOD (p=0.003) and conjugated dienes (p=0.002) were significantly higher in diabetic than in non-diabetic group. Lens SOD and GPx were moderately increased while MDA and GSH were unchanged in diabetic, compared with non-diabetic SC group. Blood HbA1C concentration was positively correlated with lens XOD (rho=0.346; p<0.001) as well as serum XOD activity (rho=0.485; p<0.001). These results suggest that poor glycemic control may upregulate systemic and ocular XOD activities contributing to lens oxidative stress and possibly to earlier onset of cataract.