I. Durak

Role of Oxidative Stress in Intrauterine Growth Restriction

Aims: The objectives of this study were to determine the role of oxidative stress in intrauterine growth restriction (IUGR) and to investigate the possible molecular mechanism(s) leading to oxidant stress in IUGR. Methods: Parameters of the oxidative and antioxidant system were evaluated in maternal plasma, umbilical cord blood, and placental tissue of pregnant women with IUGR fetuses. The same samples were obtained from women with normal pregnancies and were evaluated. Results: The results of this study indicate that while the levels of malondialdehyde (MDA) and xanthine oxidase (XO) were higher in maternal plasma, umbilical cord plasma, and placental tissues of the patients with IUGR when compared to the control group [MDA: 142.8 ± 18.0 vs. 86.4 ± 22.5 nmol/ml, 151.6 ± 25.8 vs. 93.3 ± 7.4 nmol/ml, and 0.72 ± 0.19 vs. 0.42 ± 0.09 nmol/mg protein, respectively (for all p < 0.0005); XO: 1.251 ± 0.674 vs. 0.20 ± 0.019 mIU/ml (p < 0.0005), 1.97 ± 0.73 vs. 0.237 ± 0.143 mIU/ml (p < 0.0005), and 0.023 ± 0.0012 vs. 0.012 ± 0.004 mIU/ml (p < 0.025), respectively], the levels of antioxidant potential were identified to be lower in maternal plasma, umbilical cord plasma, and placental tissues of the patients with IUGR: 63.3 ± 11.9 vs. 198.0 ± 31.9 U/ml (p < 0.0005), 32.6 ± 3.7 vs. 206.5 ± 27.1 U/ml (p < 0.0005), and 0.56 ± 0.23 vs. 1.16 ± 0.29 U/ml (p < 0.0005), respectively. On the other hand, the activities of adenosine deaminase of the IUGR patients were higher than those of the control group in maternal plasma (204.8 ± 103.5 vs. 115.6 ± 31.8 U/l, p < 0.01) and umbilical cord blood samples (584.2 ± 285.2 vs. 147.9 ± 44.8 U/l, p < 0.0005) which may suggest that oxidative stress has a role in IUGR. Moreover, an increased superoxide dismutase activity in maternal plasma (128.2 ± 37.4 vs. 88.8 ± 16.6 U/ml, p < 0.005) and cord blood (162.1 ± 37.0 vs. 116.6 ± 20.7 U/ml, p < 0.005) and an increased glutathione peroxidase activity in maternal plasma (1.83 ± 0.26 vs. 1.47 ± 0.31 IU/ml, p < 0.01) and placental tissue (0.007 ± 0.0015 vs. 0.003 ± 0.0012 IU/ml, p < 0.0005) were detected, while decreased catalase activities in cord blood (23,717 ± 3,538 vs. 16,397 ± 2,771 IU/ml, p < 0.0005) and placental tissue (47.2 ± 17.2 vs. 70.7 ± 11.3 IU/ml, p < 0.005) were identified in IUGR groups. Conclusions: In the light of the results of this study, it can be stated that the oxidative stress increases in patients with IUGR. Providing high-risk patients with an antioxidant may be useful in the prevention or treatment of IUGR, although it is a condition with no certain treatment outcome.

ACTIVITIES OF TOTAL, CYTOPLASMIC, AND MITOCHONDRIAL SUPEROXIDE DISMUTASE ENZYMES IN SERA AND PLEURAL FLUIDS FROM PATIENTS WITH LUNG CANCER

In this study, total cytoplasmic (Cu, Zn‐SOD) and mitochondrial (Mn‐SOD) superoxide dismutase activities were measured in sera and pleural fluids from patients with squamous cell carcinoma of the lung. The results were compared with those of control subjects and those of patients with tuberculosis and chronic heart failure. Serum activities were found higher in all patient groups compared to control group. Highest values were however in tuberculosis group. In the correlation analysis, meaningful intra‐ and inter‐correlations were established between enzyme activities in the samples.

Reduced Erythrocyte Defense Mechanisms against Free Radical Toxicity in Patients with Chronic Renal Failure

In this study, activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) enzymes were determined in the erythrocytes from patients with chronic renal failure (CRF) and from healthy subjects. In the conservative drug management group and intermittent ambulatory peritoneal dialysis group, CAT activity was lower than in the control group. However, SOD and GSH-Px activities of these groups were not statistically different from the control values. In the continuous ambulatory peritoneal dialysis group and the hemodialysis group, SOD, GSH-Px and CAT activities were lower than control values. In the patient groups, correlation coefficients between the enzyme activities were also found to be different from the control values. Results suggested that enzymatic antioxidant defense mechanisms were suppressed in the erythrocytes from the patients with CRF, in particular in the erythrocytes from those who were under hemodialysis and continuous ambulatory peritoneal dialysis management. It is proposed that reduced antioxidant defense mechanisms in the erythrocytes is one of the important factors leading to peroxidation in the membrane lipid structure of the erythrocytes and thereby to hemolysis and anemia in the patients with CRF.

Impaired antioxidant defense system in the kidney tissues from rabbits treated with cyclosporine. Protective effects of vitamins E and C.

Enzymatic antioxidant defense system and antioxidant defense potential (AOP) were studied in kidney tissue from rabbits treated with cyclosporine (CsA, 25 mg/kg/day), antioxidant vitamins (E, 100 mg/kg/day plus C, 200 mg/kg/day), and CsA plus antioxidant vitamins, and in kidney tissue from control animals. Although no change was observed in superoxide dismutase (SOD) activity, glutathione peroxidase (GSH-Px) and catalase (CAT) activities were found decreased in kidney tissue exposed to CsA for 10 days compared with control tissue. The level of thiobarbituric acid-reagent substances (TBARS) was higher and antioxidant defense potential (AOP) lower in the CsA-treated group compared with the other groups. Histopathological examination reveals important subcellular damage in the renal tissue from the animals treated with CsA. Antioxidant vitamin therapy caused full improvement in the enzyme activities, TBARS levels and AOP, but the subcellular damage was partly ameliorated in the CsA plus vitamin group. Results suggest that CsA impairs the antioxidant defense system and reduces the antioxidant defense potential in the renal tissue. Antioxidant vitamin treatment protects the tissue in part against toxic effects of the drug.

Oxidant/antioxidant status of plasma samples from patients with rheumatoid arthritis.

Abstract This study aims to elucidate plasma oxidant/antioxidant status in patients with rheumatoid arthritis (RA). Fasting blood samples were obtained from 24 patients with RA and 20 control subjects. Antioxidant potential (AOP) value, nonenzymatic superoxide radical scavenger activity (NSSA), and malondialdehyde (MDA) levels were measured to establish plasma oxidant/antioxidant status in the patient and control groups. Patients with RA had lower AOP and NSSA but higher MDA levels than those of the control subjects, which was an indication of reduced antioxidant capacity and oxidant stress in these patients. Results suggest that the antioxidant system is impaired and peroxidation reactions are accelerated in patients with RA. We suppose that therapeutic use of some antioxidants may be beneficial in this regard.

Effects of Mobile Phones on Oxidant/Antioxidant Balance in Cornea and Lens of Rats

Purpose: To investigate the effects of mobile-phone-emitted radiation on the oxidant/antioxidant balance in corneal and lens tissues and to observe any protective effects of vitamin C in this setting. Methods: Forty female albino Wistar rats were assigned to one of four groups containing 10 rats each. One group received a standardized daily dose of mobile phone radiation for 4 weeks. The second group received this same treatment along with a daily oral dose of vitamin C (250 mg/kg). The third group received this dose of vitamin C alone, while the fourth group received standard laboratory care and served as a control. In corneal and lens tissues, malondialdehyde (MDA) levels and activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) were measured with spectrophotometric methods. Results: In corneal tissue, MDA level and CAT activity significantly increased in the mobile phone group compared with the mobile phone plus vitamin C group and the control group (p < 0.05), whereas SOD activity was significantly decreased (p < 0.05). In the lens tissues, only the MDA level significantly increased in the mobile phone group relative to mobile phone plus vitamin C group and the control groups (p < 0.05). In lens tissue, significant differences were not found between the groups in terms of SOD, GSH-Px, or CAT (p > 0.05). Conclusions: The results of this study suggest that mobile telephone radiation leads to oxidative stress in corneal and lens tissues and that antioxidants such as vitamin C can help to prevent these effects.

Oxidant/antioxidant status of the erythrocytes from patients with rheumatoid arthritis.

Abstract: It has been suggested that enzymatic and/or non-enzymatic antioxidant systems are impaired in rheumatoid arthritis (RA) and hence patients are exposed to oxidant stress. This study aimed to establish whether this is really the case. Fasting blood samples were obtained from 24 patients with rheumatoid arthritis and 20 controls. The activities of erythrocyte superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and xanthine oxidase (XO) enzymes and malondialdehyde (MDA), oxidant resistant (OR) and non-enzymatic superoxide radical scavenger activity (NSSA) values were measured in both groups. Patients with RA had higher SOD and XO activities and MDA levels than did the controls. However, NSSA and OR levels were found to be decreased, and CAT and GSH-Px activities unchanged in the study group. Results suggest that excessive free radical production through the xanthine–xanthine oxidase system is the primary factor in rheumatoid arthritis, rather than an impaired antioxidant system. The therapeutic use of XO enzyme inhibitors and some antioxidants can be beneficial in this regard.

Reduced enzymatic antioxidant defense mechanism in kidney tissues from gentamicin-treated guinea pigs : effects of vitamins E and C

In this study, the activities of major enzymes participating in free radical metabolism (xanthine oxidase, XO; Cu,Zn and Mn superoxide dismutases, SOD; glutathione peroxidase, GSH-Px; catalase, CAT) were measured in kidney tissues from guinea pigs treated with gentamicin alone (200 mg/kg/day), gentamicin plus vitamin C (600 mg/kg/day), gentamicin plus vitamin E (400 mg/kg/day), and gentamicin plus vitamins C and E together for 10 days, and from animals treated with physiological saline solution alone during this period. We found no significant differences between control and gentamicin groups with respect to XO and Cu,Zn-SOD activities. However, the activities of Mn-SOD, GSH-Px, and CAT were found to be significantly depressed in the gentamicin-treated group relative to controls. In the gentamicin plus vitamin C group, the renal tissue Mn-SOD activity was found to be higher as compared with control and gentamicin groups. In this group, XO, GSH-Px and CAT activities were also higher than in the gentamicin-treated group, but no statistically significant differences existed between the values of this group and controls. Similar results were also observed in the gentamicin plus vitamin E group for Mn-SOD, GSH-Px, CAT, and XO. In this group, the Cu,Zn-SOD activity was found to be decreased as compared with control and gentamicin groups. In the gentamicin plus vitamins C and E group, the Cu,Zn-SOD activity was found to be decreased, the XO activity to be unchanged, and Mn-SOD, GSH-Px, and CAT activities to be increased as compared with the gentamicin and control groups. The results suggest that the enzymatic antioxidant defense system was significantly disturbed because of the suppressed activities of Mn-SOD, GSH-Px, and CAT in the kidney tissues from animals treated with gentamicin. However, vitamins C and E given concurrently with gentamicin completely abrogated this enzymatic suppression.

CISPLATIN INDUCES ACUTE RENAL FAILURE BY IMPAIRING ANTIOXIDANT SYSTEM IN GUINEA PIGS: EFFECTS OF ANTIOXIDANT SUPPLEMENTATION ON THE CISPLATIN NEPHROTOXICITY

This study aims to investigate the role of oxidants in cisplatin-induced nephrotoxicity. Cisplatin was administered intraperitoneally (i.p.) in a single dose (5 mg/kg) and guinea pigs were killed either after 24 h or 7 days. The same experiment was performed using animals treated with vitamins C and E combination and a natural antioxidant extract (SARMEX®). The kidneys were then removed to be used in the analyses. Blood samples were also obtained from the animals to be used in routine biochemical assays. Twenty-four hours after treatment there was a significant decrease in the renal activities of total superoxide scavenger activity (TSSA), superoxide dismutase (SOD) and catalase (CAT) accompanied by a rise in malondialdehyde (MDA) levels. After 7 days, the fall in kidney enzymatic activities was far greater, while the increase in blood urea (BUN) and creatinine (CRE) was marked. Treatment with antioxidants causes significant increases in renal TSSA (7 day), non-enzymatic superoxide scavenger activity (NSSA) (24 h and 7 day) and SOD (7 day) activities, does not change glutathione peroxidase (GSH-Px) activity and decreases renal MDA (24 h and 7 day), blood BUN (7 day) and CRE (7 day) levels. Our results suggest that cisplatin treatment impairs both enzymatic and non-enzymatic antioxidant systems and causes peroxidation in the renal tissue, which leads to kidney failure. Antioxidant supplementation strengthens the renal antioxidant system, eliminates oxidation reactions, and prevents cisplatin-induced kidney failure.

Activities of adenosine deaminase, 5'-nucleotidase, guanase, and cytidine deaminase enzymes in cancerous and non-cancerous human breast tissues.

We measured activities of some DNA turnover enzymes in 9 breast tissues with stage II cancer, 6 breast tissues with stage IIIa cancer, and 9 non-cancerous adjacent breast tissues from the same patients with stage II cancer. We found higher Adenosine Deaminase (ADA) and 5′-Nucleotidase (5′NT) and lower Guanase (GUA) activities in the cancerous tissues compared with the non-cancerous ones. No meaningful differences were however found between Cytidine Deaminase (CD) activities. Regarding the correlation analysis, positive correlations were established between ADA and 5′NT activities of the cancerous tissues (r = 0.45 for the tissues with stage II and r = 0.60 for the tissues with stage IIIa cancer). No meaningful correlations were however found between other enzyme activities. Relating to activity ratios, no meaningful differences were found between ADA/5′NT values in the tissues. GUA/CD ratios were however lower and the other ratios higher in the cancerous tissues.Results indicated that ADA and 5′NT activities increased and GUA activity decreased in the cancerous breast tissues but CD activities did not change in the tissues affected. It has been suggested that increased ADA and 5′NT together with decreased GUA activities might be a physiologic attempt of the cancer cells to provide more substrates needed by cancer cells to accelerate the salvage pathway activity. Furthermore, high ADA activity might also play part in the detoxication process of high amounts of toxic adenosine and deoxyadenosine substrates produced from accelerated purine metabolism in the cancerous tissues.