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

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.

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

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.

Activities of DNA turnover and free radical metabolizing enzymes in cancerous human prostate tissue

Activities of adenosine deaminase (ADA), 5'nucleotidase (5'NT), xanthine oxidase (XO), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) and levels of thiobarbituric acid reagent substances (TBARS) were measured in 10 cancerous and 10 noncancerous human prostate tissues. Decreased activities of DNA turnover enzymes (ADA and 5'NT), increased activities of GSH-Px and CAT, and unchanged activities of SOD and XO were observed in cancerous prostate tissues compared with those of noncancerous ones. TBARS levels were found to be higher in cancerous tissues than noncancerous ones. In correlation analysis, mostly positive correlations were established between enzyme activities of the cancerous tissues, whereas no meaningful correlations were found between enzyme activities of the noncancerous tissues except for a positive correlation between XO and SOD. The results indicate that the activities of DNA turnover enzymes were reduced, which was possibly an attempt to lower the rate of purine catabolism, and the activities of GSH-Px and CAT enzymes were increased, probably in response to increased free radical stress occurring in cancerous prostate tissues. Increased concentrations of TBARS suggested oxidant stress and thus accelerated peroxidative reactions in the cancerous tissues, even though antioxidant defense mechanisms were activated. These findings suggest that enzymatic antioxidant systems of cancerous prostate tissues cannot sufficiently eliminate oxidant factors and prevent cellular peroxidative reactions occurring during the carcinogenic process.

Reduced antioxidant defense capacity in myocardial tissue from guinea pigs treated with 5-fluorouracil

Antioxidant defense capacity was investigated in myocardial tissue from guinea pigs treated with 5-fluorouracil (5-FU) at a dose of 400 mg/kg/d daily for 5 d administered intraperitonally. Treatment with 5-FU lowered the activities of cardiac superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) accompanied by higher catalase (CAT) activity. Further, antioxidant potential (AOP) values were lower but oxidation resistance (OR) and malondialdehyde (MDA) levels were higher in the 5-FU-treated tissue. With regard to myocardial iron (Fe) and copper (Cu) levels, no significant differences were found between the groups. Results suggest that 5-FU treatment causes impairment in the myocardial antioxidant defense system and leads to cardiac peroxidation. It has been postulated that these changes might be responsible for the 5-FU cardiotoxicity seen in some patients, and antioxidant therapy might provide a therapeutic advantage.

Effects of isoflurane on nitric oxide metabolism and oxidant status of guinea pig myocardium

BACKGROUND

Volatile anesthetics (VAs) have been shown to enhance myocardial recovery during reperfusion, the mechanism of which has not been clarified yet. It has been supposed that this effect of VAs may appear through antioxidative mechanisms.

METHODS

Thirty guinea pigs were used in the study. There were three groups with 10 animals in each: I - control, II - isoflurane+oxygen and III - oxygen. Isoflurane (2.0% v/v) and oxygen (100%) mixture was given to the animals via a face mask in the isoflurane+oxygen group at the rate of 21 per min for 30 min a day for three consecutive days. In the oxygen group, oxygen alone (100%) was given under the same conditions as in the isoflurane+oxygen group. At the end of the experiments, the animals were killed and their hearts were removed. In the heart tissues, nitric oxide synthase (NOS) activity, nitric oxide (NO) pool (NO*+NO2-) and malondialdehyde (MDA) levels were measured.

RESULTS

NOS activity was found to be higher and the NO pool lower in the isoflurane+oxygen group compared with those of control and oxygen groups. In the oxygen group, MDA level was found to be higher compared to the other groups. There was, however, no significant difference between MDA levels of the control and isoflurane+oxygen groups.

CONCLUSION

Our results suggest that isoflurane prevents peroxidation reactions in heart tissue, possibly by scavenging toxic oxygen radicals produced under hyperoxygenation conditions as occurs with general anesthesia.

Peroxidation in muscle and liver tissues from fish in a contaminated river due to a petroleum refinery industry

In this study, we aimed to investigate the possible effects of the wastewater water contamination of a petroleum industry on the oxidant/antioxidant status of muscle and liver tissues from fish in the Kizilirmak River, Kirikkale, Turkey. The antioxidant/oxidant parameters were analyzed in the muscle and liver tissues from fish in 10 km of the river above and below the industry. Malondialdehyde (MDA) and susceptibility to oxidation (SO) values were measured in the liver and muscle tissues as indexes of oxidation, and antioxidant potential (AOP), superoxide dismutase (SOD), glutathion peroxidase (GSH-Px), and catalase(CAT) activities were measured as indexes of antioxidant status. There was significant oxidation in the muscle tissue of the fish obtained in the river downstream of the industry compared to those obtained upstream of the industry. Although there were no meaningful differences between the SOD and GSH-Px activities, the AOP value and CAT activities were found to be reduced in the muscle tissues from the fish obtained downstream. In the liver tissues, the SOD and GSH-Px activities were found to be increased in the fish obtained downstream but no differences were observed in the MDA, SO, AOP, and CAT values. Our results suggest that some contaminants from the petrochemical industry cause oxidation in fish muscle tissues by impairing the antioxidant system. However, because no peroxidation was observed in the liver tissue from the downstream fish, it is possible that liver tissues have a stronger antioxidant capacity than muscle.

Antioxidant defense potential of rabbit renal tissues after ESWL: protective effects of antioxidant vitamins

Antioxidant defense potential, malondialdehyde (MDA) levels, and relative hydroxyl radical (OH.) concentrations were measured in order to establish the effects of extracorporeal shock wave lithotripsy (ESWL) on free radical production and antioxidant defense potential of the rabbit kidney tissues. Electron microscopic examination was also performed to observe ultrastructural changes. The antioxidant defense potential of the ESWL-treated tissues was found to be reduced, and the MDA levels increased as compared with controls. Vitamin (vitamin E plus C combination) pretreatment ameliorated antioxidant defense potential in part, prevented increases in MDA levels in the ESWL-treated tissues, and increased the antioxidant defense potential in the control kidney tissues. After ESWL, a significant amount of OH. radical was measured in the affected tissue. This revealed the source of oxidant stress and peroxidation reactions in the ESWL-treated kidney tissue. Vitamin pretreatment caused significant reduction in the OH. radical concentration. In the electron microscopic investigation, some significant subcellular changes, such as endothelial injury, loss of foot processes, damage of glomerular basal membrane, etc., were observed in the ESWL-treated renal tissue slices. Vitamin pretreatment to a great extent prevented formation of these subcellular changes. Our results suggest that the antioxidant capacity of the kidney tissue was reduced after ESWL treatment and that the tissue was exposed to oxidant stress. Vitamin pretreatment exerted significant protection against the radical damage.

Halothane hepatotoxicity and hepatic free radical metabolism in guinea pigs; the effects of vitamin E

PURPOSE

The aim of this study was to investigate the relation between halothane hepatotoxicity and hepatic free radical metabolism and to establish a possible protective role of vitamin E against halothane hepatotoxicity.

METHODS

Twenty-eight guinea pigs were used in the experiments. Halothane (1.5% v/v) in oxygen (100%) was given to the animals for 90 min over three days. Livers from animals were then taken and prepared for the assays. In the enzymatic study, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) activities were measured. As a peroxidation index, the malondialdehyde (MDA) concentration was determined. Also, electron spin resonance (ESR) analysis and electron microscopy (EM) were performed.

RESULTS

Superoxide dismutase (1168.3 +/- 78.2 U.mg-1) and glutathione peroxidase (14.9 +/- 6.2 mIU.mg-1) activities were decreased, but catalase activity (1260.0 +/- 250.6 IU.mg-1) and malondialdehyde concentration (11.5 +/- 1.8 ppb) were increased in liver tissues exposed to halothane compared with control values (1382.2 +/- 91.8 U.mg-1 for SOD, 27.8 +/- 5.2 mIU.mg-1 for GSH-Px, 840.2 +/- 252.4 IU.mg-1 for CAT and 10.0 +/- 1.0 ppb for MDA). Electron spin resonance analysis revealed a peak of CF3CHCl. radical in the exposed tissue. Electron microscopy indicated ultrastructural changes in the hepatic cells of both halothane groups with and without vitamin E treatment.

CONCLUSION

Halothane causes impairment in the hepatic antioxidant defense system and accelerates peroxidation reactions. As a result, some ultrastructural changes in hepatic tissues occur due to halothane treatment. Although vitamin E prevents peroxidative damage, it does not ameliorate ultrastructural changes caused by halothane treatment. This shows that halothane toxicity results not only from impaired hepatic antioxidant defense system but also from other, unknown causes.

Acute effects of smoking of cigarettes with different tar content on plasma oxidant/antioxidant status

In this study, acute effects of two different types of cigarette smoking on plasma oxidant/antioxidant status were investigated. For this purpose, malondialdehyde (MDA) levels and antioxidant potential (AOP) values were measured in the plasma samples before and after cigarette smoking at fasting. After the first blood sample was obtained, second and third samples were withdrawn at 1.5 h and 3 h. In the first group, subjects smoked five cigarettes with full flavor (FF), and in the second group, five cigarettes with full-flavor low tar (FFLT). Quality classification is made mainly on the basis of tar content of the products. The cigarette with 23 mg tar is defined as FF and that with 12 mg tar as FFLT. MDA level was found to be significantly increased in the 1.5-h plasma samples of both groups, but the increase was greater in the FF group. AOP values, however, were found to be lower in the 3-h plasma samples of both groups, but the decrease was greater in the FF group compared with the FFLT group. It appears that acute smoking causes oxidant stress in blood plasma once exposed to smoke, and then this effect (MDA) begins to decrease. On the other hand, AOP is lowered due to oxidant stress created by smoke. With regard to the types of cigarettes, the FF product seems to be more oxidant than the FFLT product. Our results suggest that antioxidant supplementation might be beneficial for the smokers to cope with the oxidant load derived from cigarette smoke. It is also clearly seen from these results that cigarette manufacturers should reduce tar/nicotine ratio in their products in order to lessen the toxic effects of smoking without causing increased need to smoke.

Oxidant status increased during fracture healing in rats

We evaluated oxidant status during bone healing in 50 rats. In 40 rats, the right tibia was fractured and fixed intramedullarly (study leg) and the left tibia was pinned but not fractured (control leg). Rats were killed on days 1, 3, 7, 14, 28 and malondialdehyde (MDA) levels were determined in tibial bone tissue. The MDA levels of study and control legs were compared with basal MDA levels in bone in 10 rats. There was no apparent difference between the basal level and control legs, but the study legs showed a statistically significant increase in MDA levels on days 7 and 14. We conclude that no oxidative stress injury occurs during the ischemic period of fracture healing, but it may be significant during inflammation and the formation of callus.

Effects of cigarette smoking with different tar content on erythrocyte oxidant/antioxidant status

In this study, the effects of cigarettes with differing tar content on erythrocyte oxidant/antioxidant status was investigated. Malondialdehyde (MDA) as an indicator of oxidant status and superoxide radical scavenger activity (SSA) as an indicator of antioxidant status were measured in erythrocytes from 20 smokers and 10 non-smoker controls. Ten of the 20 smoking subjects smoked five cigarettes with full flavour low tar (FFLT with 12 mg tar) and the others smoked five cigarettes with full flavour high tar (FF with 23 mg tar) over 1 hour. Initial blood samples from both groups at fasting, followed by further samples from smokers at 1.5 hours and 3 hours after smoking. Initial erythrocyte MDA level and SSA activity were found to be higher in the smoking groups compared to non-smokers. Furthermore, both parameters were significantly higher at the 1.5-hour and 3-hour erythrocyte samples when compared to initial values in the FFLT group. However, there were no statistically significant differences between SSA values established at different times in FF group. Results suggest that smoking causes oxidant load in the erythrocytes. Although a compensatory mechanism (i.e. increased SSA activities) develops in the FFLT group after smoking, this cannot prevent peroxidation reactions (i.e. increased MDA levels) in the erythrocytes. As to the types of cigarettes, both seem to have oxidant potential, but oxidation degree in the FFLT group is higher than that of FF group. These results suggest that antioxidant supplementation to smokers might be beneficial to decrease cellular oxidation damages.

Aspirin impairs antioxidant system and causes peroxidation in human erythrocytes and guinea pig myocardial tissue

This study aims to investigate possible effects of aspirin treatment on cellular oxidant/antioxidant system. In the first part of the study, 15 guinea pigs were given aspirin at three different doses (2200, 440 and 10 mg/kg/day) for 30 days and five were fed on the same diet without aspirin. After a month, animals were killed and their hearts were removed for use in analyses. In the other part, after fasting blood samples were obtained from 11 volunteer subjects, they were given aspirin (approximately 10 mg/kg/day) for 30 days and second blood samples were obtained after 1 month. Five volunteer subjects also participated as placebo control. Oxidant/antioxidant parameters, namely superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), malondialdehyde (MDA), nonenzymatic superoxide scavenger activity (NSSA), susceptibility to oxidation (SO) and antioxidant potential (AOP) values, were assayed in the samples. Antioxidant system was found to be impaired in the heart tissue from guinea pigs and in the erythrocytes from volunteer subjects. AOP and NSSA values were lower and MDA higher after aspirin treatment in both heart tissues and erythrocytes. In guinea pig heart tissue, SO was lower, but GSH-Px and CAT were unchanged after aspirin treatment. In human erythrocytes, SO was unchanged, but GSH-Px and CAT activities were increased after aspirin treatment. Changes in guinea pig heart tissues from animals treated with higher aspirin doses were more drastic relative to those of human erythrocytes, but no meaningful differences were observed between analysis parameters of control and lower-dose (10 mg/kg/day) aspirin-treated animals. Our results suggest that high-dose aspirin exerts significant toxicity to guinea pig myocardium and normal dose aspirin may cause peroxidation in the human erythrocytes due to its oxidant potential. We suppose that antioxidant supplementation may be beneficial for the people using aspirin for longer periods in order to prevent peroxidation damages.

Effects of smoking on plasma and erythrocyte antioxidant defense systems

In this study, activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) enzymes were measured in the erythrocytes, and levels of thiobarbituric acid-reactive substances (TBARS) and antioxidant potential (AOP) values were measured in both erythrocyte and plasma samples from smokerS and nonsmokers. No significant differences were observed in erythrocyte parameters, serum triglycerides, and total cholesterol. AOP was significantly lower and TBARS level higher in the plasma samples from smokers compared with those of nonsmokers. Results suggest that smoking causes no impairment in the enzymatic antioxidant defense system and does not lead to oxidant stress in the erythrocytes, possibly because these cells have potent antioxidant defense capacity.

The effects of cyclosporine on antioxidant enzyme activities and malondialdehyde levels in rabbit hepatic tissues

Possible molecular mechanisms leading to cyclosporine-induced hepatotoxicity has not been cleared yet. Therefore, investigation of antioxidant status of hepatic tissues exposed to cyclosporine A (CsA) and of free radical involvement in the CsA-induced hepatotoxicity seems of importance. For this aim, 20 rabbits were used in the study. In each group (control, CsA, CsA plus vitamin and, vitamin only) there were 5 animals. CsA was given orally (25 mg/kg/day) for 10 days. Vitamins E (100 mg/kg/ day) and C (200 mg/kg/day) combination was injected intramuscularly. After 10th day, animals were killed, and livers were prepared for the enzymatic assays. Activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) and, malondialdehyde (MDA) levels were determined in the supernatant fractions. Lowered SOD, unchanged GSH-Px and, increased CAT activities and MDA levels were detected in hepatic tissues of rabbits treated with CsA as compared with controls. In the CsA plus vitamin group, SOD activity was found to be higher, GSH-Px and CAT activities unchanged and MDA levels lower than the CsA group. In the vitamin-treated group, all of the enzyme activities were higher than the controls but MDA levels were unchanged. Correlation analysis revealed some significant differences between the groups. Results suggest that cyclosporine impairs the antioxidant defense system and thus, leads to oxidant stress and peroxidation in rabbit hepatic tissues. It has been established that this process can be prevented by antioxidant vitamin supplementation.

Comparison of antioxidant potentials of red wine, white wine, grape juice and alcohol

Antioxidant potential (AOP) and non-enzymatic superoxide radical scavenger activity (NSSA) values of red wine, white wine, grape juice and ethyl alcohol were assessed and values were compared. The effects of these beverages on serum AOP and NSSA values were also measured in vitro. Red wine, white wine and grape juice exert strong antioxidant activity in similar degrees and all produce significant effects on serum AOP and NSSA values. However, ethyl alcohol does not have either AOP or NSSA, nor does it have an effect on serum AOP or NSSA values. AOP values (nmol/ml h) of red wine, white wine and grape juice were 20.8 +/- 4.2, 23.2 +/- 4.0 and 24.6 +/- 4.8, respectively. NSSA values (U/ml) of red wine, white wine and grape juice were 30.4 +/- 6.8, 26.8 +/- 5.6 and 32.6 +/- 5.8, respectively. There were no statistically meaningful differences between AOP and NSSA values of the groups (p > 0.05 for all). Results suggest that red wine, white wine and grape juice all have high antioxidant potential to protect cellular structures against peroxidation reaction owing to their rich phenolic contents.

Isoflurane impairs antioxidant defence system in guinea pig kidney

PURPOSE

To investigate whether free radical metabolism is changed due to isoflurane treatment and, if so, to elucidate the role of changed free radical metabolism in the nephrotoxicity.

MATERIALS AND METHODS

Fifteen guinea pigs were used in the study. Five were treated with isoflurane in oxygen, five with oxygen and five were controls. Animals were exposed to isoflurane and oxygen three times. Each treatment was performed for 30 min once a day for three consecutive days. Activities of free radical enzymes, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px); values of antioxidant parameters, antioxidant potential (AOP), non-enzymatic superoxide radical scavenger activity (NSSA) and oxidation resistance (OR) and, level of an oxidant parameter namely, malondialdehyde (MDA) were determined in the renal tissues of the groups. Blood was also obtained for serum creatinine and urea analyses.

RESULTS

AOP, NSSA, SOD and CAT activities were decreased; (0.0188 +/- 0.0026 vs 0.0156 +/- 0.0015, P < 0.025; 8.72 +/- 1.80 vs 6.40 +/- 1.22, P < 0.05; 76.71 +/- 18.54 vs 52.79 +/- 11.68, P < 0.025; 71.26 +/- 15.58 vs 55.39 +/- 8.83; P < 0.05, respectively) but, MDA level, OR value and GSH-Px activities increased (10.89 +/- 1.57 vs 15.87 +/- 2.97, P < 0.01; 0.84 +/- 0.34 vs 2.28 +/- 1.39, P < 0.05; 1.45 +/- 0.83 vs 3.45 +/- 1.20, P < 0.01, respectively) in kidney tissues from isoflurane-treated group compared with controls. No differences were observed between control and oxygen groups with regard to all analysis parameters except GSH-Px.

CONCLUSION

Isoflurane impairs the antioxidant defence system and this oxidant stress may play a part in the isoflurane-induced renal toxicity.

Blood oxidant/antioxidant status of atherosclerotic patients

In the present study, it is aimed to investigate oxidant/antioxidant status of plasma and erythrocytes from atherosclerotic patients and to establish the possible role of oxidant stress in the formation and progression of atherosclerosis. Antioxidant potential (AOP) values and malondialdehyde (MDA) levels were studied in erythrocyte and plasma samples from 40 atherosclerotic patients and 38 healthy controls. A total of 13 subjects in each group were smokers. AOP was found unchanged in erythrocytes but lower in plasma samples (P<0.0005) from atherosclerotic patients as compared with those of the controls. MDA levels were however higher in erythrocyte hemolysate (P<0.025), erythrocyte membrane (P<0.0005) and blood plasma samples (P<0.0005) from atherosclerotic patients than those of the controls. Moreover, AOP was found to be lower in plasma samples of smoker patients than that of non-smoker patients (P<0.05). In the control group, erythrocyte MDA level was higher in smoker group than that of non-smoker group (P<0.05). Results reveal the presence of oxidant stress in the blood samples from patients with atherosclerosis. It seems antioxidant therapy might give beneficial results for atherosclerotic patients.

The effect of red wine on blood antioxidant potential

We investigated the effects of red wine on blood antioxidant potential in an attempt to elucidate molecular mechanisms concerning the possible protective role of red wine in atherosclerosis. Volunteer subjects in the study group consumed a standard meal and drank red wine (5 mg/kg) while controls consumed the same meal and drank water. Over 4 1/2 hours, blood samples were taken, and malondialdehyde (MDA) and antioxidant potential (AOP, obtained from MDA levels before and after superoxide radical attack) values were measured in the plasma and erythrocytes. We found that AOP values of plasma and erythrocyte samples from the study group were at their highest after 1 1/2 hours and then declined to basal values at 4 1/2 hours. There were no statistically significant differences between the basal AOP values of the study group and the control group. With regard to MDA levels, gradual increases were seen in the plasma of the control group during the 3 hours after food, but no changes were seen in the plasma of the study group in this period. Although there were increases in erythrocyte MDA levels of both groups over 3 hours, the MDA production rate was significantly higher in the control group. Our results suggest that red wine causes significant increases in AOP values of plasma and erythrocytes, which may prevent cellular peroxidation reactions and lessen atherosclerotic complications through inhibition of LDL.

Erythrocyte oxidant/antioxidant status of diabetic patients

Present study aims to establish erythrocyte oxidant/antioxidant status in diabetic patients with and without atherosclerotic complications. Fasting blood samples were obtained from 23 diabetic and 12 control subjects. Thirteen patients had no disease other than diabetes mellitus and 10 patients had also atherosclerosis in addition to diabetes mellitus. Erythrocyte antioxidant potential (AOP) and thiobarbituric acid reagent substances (TBARS) levels were measured in these patients and results were compared with those of controls, who were chosen among healthy subjects. Results suggest that although there is an oxidant stress in the erythrocytes of diabetics, this is not due to reduced erythrocyte antioxidant defence potential but, rather, increased free radical production possibly due to hyperglycemia.

Seminal arginase activity in infertility

Arginase (Arg) activity in seminal plasma and sperm cells from infertile men and healthy fertile donors was measured. There were no statistically meaningful differences in seminal plasma Arg activity between the two groups whereas sperm cells from oligospermic infertile men had a higher Arg activity compared with the controls. Some important correlations were established between sperm count and Arg activity (negative values) and sperm motility and Arg activity (positive values) in both sperm cells and plasma samples from infertile men. Results suggest that the arginine-nitric oxide pathway within sperm cells from oligospermic infertile men is disturbed by enhanced Arg activity. We think that this may play a part in sperm dysfunction and male infertility.

The effects of gentamicin on the activities of glutathione peroxidase and superoxide dismutase enzymes and malondialdehyde levels in heart tissues of guinea pigs

In this study, superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities and malondialdehyde (MDA) levels were measured in heart tissues from guinea pigs treated with gentamicin and gentamicin plus vitamin E combination. Mean values were compared with those of the controls treated with only physiological saline solution. The activities of SOD and GSH-Px were found to be lower and the MDA level higher in the hearts from gentamicin-treated animals compared with those of the controls. In the gentamicin plus vitamin E group, however, tissue SOD activity was found to be increased and MDA level decreased significantly relative to the gentamicin group. GSH-Px activity was lowest in this group. Results suggest that gentamicin suppresses SOD and GSH-Px activities in heart tissue, thereby making the tissue more vulnerable to oxidative stress and peroxidative attacks, an important indicator of which is increased MDA level in the heart tissues from gentamicin-treated guinea pigs. This effect might be deleterious when gentamicin is used after cardiac surgery since a potential risk of free radical injury exists in the heart tissue during and/or after cardiac surgery owing to ischaemia and reperfusion processes, and, possibly, in the management of the patients with certain types of heart disease. Our results showed that vitamin E given concomitantly with gentamicin could protect the heart tissue against free radical injury.

Oxidative stress in patients with chronic renal failure: effects of hemodialysis

OBJECTIVE

To investigate blood oxidative status of patients with chronic renal failure (CRF) and possible effects of hemodialysis on the development of oxidative stress in blood.

MATERIALS AND METHODS

The levels of malondialdehyde (MDA) and oxidation resistance (OR) values were measured in blood plasma, erythrocyte hemolysate and erythrocyte membrane fractions of 33 patients with CRF and of 12 healthy controls. Of the 33 patients, 17 subjects were under hemodialysis treatment.

RESULTS

MDA levels were found to be increased in all blood fractions of the patients. OR values were unchanged in erythrocyte hemolysates but decreased in plasma and erythrocyte membrane fractions of the CRF patients. Moreover, erythrocyte MDA levels were determined to be higher in hemodialyzed patients compared with both controls and non-hemodialyzed patients. OR values were lower in all blood fractions of the hemodialyzed patients relative to controls and non-hemodialyzed patients.

CONCLUSION

Results suggest that there is a significant oxidative stress (expressed as peroxidation) in blood samples from patients with CRF, which is further exacerbated by hemodialysis.