Does dialysis modality influence the oxidative stress of uremic patients?

BACKGROUND/AIMS: Since peritoneal membrane is more compatible and residual renal function better preserved during peritoneal dialysis, we questioned whether the oxidative burden in chronic kidney disease (CKD) is influenced by dialysis modality. METHODS: 49 stable CKD patients, 17 on continuous ambulatory peritoneal dialysis (CAPD), 16 on hemodialysis (HD), and 16 non-dialyzed, and 13 healthy subjects were enrolled. Plasma thiobarbituric acid-reactive substances (TBARS; nmol/g protein), serum total antioxidant activity (TAA), total plasma-free thiols (Pt-SH; µmol/g protein), albumin and uric acid were measured by spectrophotometry. Serum residual antioxidant activity (RAA) was calculated. RESULTS: TBARS were higher in HD (78.3 ± 20.3) versus both non-dialyzed (53.1 ± 27.9, p = 0.007) and CAPD groups (58.3 ± 19.8, p = 0.008). Pt-SH was reduced in CKD patients, but showed comparable values between dialysis groups. TAA and RAA were similarly increased in HD and CAPD patients than in the other two groups. CONCLUSION: Oxidative stress occurs in all CKD patients and worsens as renal function declines. Lipid peroxidation seems more augmented during chronic HD as compared to CAPD, but the plasma antioxidant status did not differ between the investigated dialysis methods. Therefore, dialysis modality appears to influence lipid peroxidation without changing the extracellular antioxidant defense of CKD patients.

Free radical activity in obese patients with type 2 diabetes mellitus.

UNLABELLED: Oxidative stress plays critical roles in the pathogenesis of various diseases. The aim of the present study was to investigate the relationship between oxidative stress, measured by plasma dicarbonyls and plasma antioxidant defence, measured by reduced glutathione (G-SH) in the whole blood, protein thiols in the plasma and erythrocyte superoxide dismutase activity in obese and obese with type-2 diabetes mellitus subjects, clinically free of complications. Twenty obese patients with type-2 diabetes mellitus and twenty nondiabetic obese patients were examined and compared with twenty healthy controls (matched for age and sex against the obese patients with or without diabetes). RESULTS: Obese patients and obese diabetic patients had lower blood glutathione than control subjects (p<0.02 and respectively p<0.04) and higher plasma MDA, an end product of lipid peroxidation (p<0.004 and respectively p<0.01). There was a significant difference between plasma MDA from obese and obese diabetic subjects (p<0.05). Plasma thiols (expressed as micromol/mg protein) did not differ between the three groups. Plasma dicarbonyls concentrations were significantly increased in obese (p<0.043) and obese diabetic patients (p<0.047) and SOD activity (U/g Hb) was significantly decreased in obese (p<0.0 ) and obese diabetic patients (p<0.05) compared to controls. Analysing the results of our study, which show that most of the markers of oxidative stress are modified in the same way in obesity and obesity with diabetes mellitus type 2, we suppose that obesity leads to oxidative stress which can contribute to obesity-associated diseases such as diabetes mellitus.

A comparative oxidative stress study--obesity with and without diabetes mellitus.

Oxidative stress and inflammation are involved in the initiation and progression of obesity and diabetes mellitus. The aim of our study was to find out some markers of oxidative stress in twenty obese patients with type 2 diabetes mellitus (group D) and twenty age-matched obese subjects (group O) and compare the results with the control values from twenty matched healthiy subjects (group H). Spectrophotometric methods were used. For the following plasma parameters: ceruloplasmin, d-ROM (determinable Reactive Oxygen Metabolites), alpha-dicarbonyls, the values were modified in the same way for the groups of patients versus healthy subjects. The patients had higher alpha-dicarbonyls levels than the controls (for D versus H, p<0.047 and for O versus H, p<0.043). There were not significant differences for plasma ceruloplasmin and d-ROM levels. Comparing group O versus D, all the above parameters had very close values. The antioxidant capacity (AC) was higher in group O versus group H (p<0.001) and higher in group O versus D (p<0.02). The high AC for obese patients may be due to hyperuricemia. A negative correlation between AC and d-ROM concentrations and a positive correlation between ceruloplasmin and AC levels was observed for group D. Our data underline that in type 2 diabetes mellitus and obesity, the plasma markers of oxidative stress are modified in the same way. Oxidative stress may be a "connector" between these two diseases. Probably body fat reduction (for obese individuals) diminishes oxidant formation and, in its turn, the incidence of obesity related diseases, such as diabetes mellitus.