Marijana Vučić

Superoxide Dismutase Activity in Lymphocytes and Polymorphonuclear Cells of Diabetic Patients

Copper-zinc superoxide dismutase (Cu,Zn-superoxide dismutase) activity was evaluated in lymphocytes and polymorphonuclear cells of insulin-dependent (n = 33) and non-insulin-dependent (n = 34) diabetic patients. A commercial method for the measurement of superoxide dismutase activity was adapted for use on a discrete analyser and evaluated for interference by other antioxidants with superoxide anion-scavenging properties. In comparison to healthy control subjects (n = 32), a significantly lower Cu,Zn-superoxide dismutase activity was found in both lymphocytes and polymorphonuclear cells of insulin-dependent (2.08 +/- 0.58 vs. 1.70 +/- 0.46 U/mg protein, p < 0.05, and 1.06 +/- 0.46 vs. 0.64 +/- 0.40 U/mg protein, p < 0.001, respectively) and non-insulin-dependent diabetic patients (2.08 +/- 0.58 vs. 1.61 +/- 0.48 U/mg protein, p < 0.01, and 1.06 +/- 0.46 vs. 0.53 +/- 0.24 U/mg protein, p < 0.001, respectively). There was a week, but significant negative correlation between age and Cu,Zn-superoxide dismutase activity in lymphocytes and polymorphonuclear cells (r = -0.22 and r = -0.28, p < 0.05, respectively), whereas no influence of gender, diabetes duration and glycaemic control was observed. The results indicate that diabetes mellitus could elicit a significant disturbance in superoxide anion-scavenging potential of lymphocytes and polymorphonuclear cells.

Relationship of sperm superoxide dismutase-like activity with other sperm-specific enzymes and experimentally induced lipid peroxidation in infertile men

Summary. Superoxide dismutase‐like activity (SOD‐like), isoenzyme lactate dehydrogenase‐C4 (LDH‐C4) and NADH‐diaphorase activities in spermatozoa have been investigated from 58 normozoospermic and 27 oligozoospermic men. Significantly higher SOD‐like, LDH‐C4 and diaphorase activities (P<0.01, P<0.005 and P<0.0001, respectively) were detected in spermatozoa from oligozoospermic men, compared to the activities found in normozoospermic samples. SOD‐like activity (mean±SE) in oligozoospermic samples amounted to 8.3±1.6 U 10−8 spermatozoa, while in spermatozoa in normozoospermic men with a sperm concentration above 20 million of spermatozoa per ml amounted to 4.2±0.5 U 10−8. There was a close correlation between the SOD‐like activity and biochemical indicators of the presence of residual cytoplasm i.e. isoenzyme LDH‐C4 and NADH‐diaphorase (r = 0.53 and r = 0.66 in normozoospermic and r = 0.63 and r = 0.54 in oligozoospermic men, respectively). A positive relationship between SOD‐like activity and experimentally‐induced lipid peroxidation was detected in 54 infertile men (r = 0.30; P<0.05). These findings suggest that a higher level of superoxide dismutase‐like activity may reflect a defect in the development or maturation of spermatozoa and, thereby, a decreased fertility potential. Hence, determination of SOD‐like activity may give information on the state of maturity of human spermatozoa, while its role in the antioxidative protection remains to be determined.

Evaluation of ascorbate and urate antioxidant capacity in human semen

Summary. The ascorbate/urate ratio in the seminal plasma was studied in 76 randomly chosen infertile men. The levels of ascorbate and urate were found to vary widely (range: 93–954 μmol 1−1 and 127–670 μmol 1−1, respectively), while the ascorbate/urate ratio was 1.03 ± 0.63 (mean ± SD), indicating almost equimolar concentrations of both compounds in more than 60% of the subjects investigated. No relationship of ascorbate with any biochemical marker of accessory sex gland secretions was observed, whereas an inverse correlation of urate with some prostatic markers, acid phosphatase (−0.37; P<0.001), zinc (−0.35; P<0.002) and citric acid (−0.33; P<0.003), was found. In vitro experiments were conducted on an artificial suspension containing ascorbate and urate at physiological levels and activated polymorphonuclear leukocytes in the normal range (as proposed by WHO) to determine the extent to which the presence of superoxide anion‐generating leukocytes contribute to the depletion of ascorbate and urate. The ascorbate level did not change in the presence of 0.2 × 106 leukocytes ml−1 while higher amounts of activated polymorphonuclear leukocytes initiated ascorbate oxidation, the intensity of which was in correlation with the extent of leukocyte contamination. After incubation (37 °C, 30 min) in the presence of 0.4, 1.0 and 1.5 × 106 cells ml−1, the average decline from the initial ascorbic acid level was 24, 43 and 49%, respectively. However, exposure of whole semen, instead of buffer, to oxidants released from the same amount of activated polymorphonuclears led to only 2.6, 11 and 22% decrease of the ascorbic acid, most probably due to the action of other superoxide anion scavenger compounds present in semen. Excessive superoxide anion production due to the presence of activated leukocytes had no influence on urate level either in the artificial suspension or in semen. The ability of ascorbate to afford protection against leukocyte‐associated superoxide anions in not hampered in the semen of infertile men, provided that leukocyte contamination does not exceed 1 × 106 cells ml−1. The possible role of urate in stabilizing the ascorbate antioxidant activity in seminal plasma should be further investigated.

Serum sialic acid in subjects with impaired glucose tolerance and in newly diagnosed type 2 diabetic patients

Abstract. Several general population studies and those carried out in diabetic patients with complications have pointed to serum sialic acid as a marker of inflammation in atherosclerosis. In this study we examined whether total sialic acid (TSA) was changed in the sera of 28 newly diagnosed subjects with type 2 diabetes (type 2 DM), 47 subjects with impaired glucose tolerance (IGT) and 72 subjects with normal glucose tolerance (NGT). The associations between sialic acid and other atherosclerotic risk factors such as lipid profile, baseline diene conjugates in low-density lipoproteins (LDL-BDC) and fasting insulin were also investigated. We found a trend to TSA increase in subjects with impaired glucose tolerance and a significant increase in TSA in newly diagnosed patients with type 2 DM (2.2±0.3 vs. 1.9±0.3 mmol/l; p<0.03) when compared to subjects with NGT. Lipid profile and LDL-BDC, as a marker of circulating oxidized LDL, did not differ among glucose tolerance categories. Significant associations between total sialic acid and 2-h post-load glucose level, fasting insulin, insulin sensitivity, HDL-cholesterol and log of triglycerides were found in the examined subjects. Multiple regression analysis showed significant correlations between serum sialic acid and 2-h post-load glucose levels and insulin sensitivity. This study indicates that measurement of TSA as a marker of subclinical inflammation may be valuable as an independent parameter in identifying subjects at higher risk of developing type 2 diabetes and those who might benefit from anti-inflammatory treatment.