The Protective Effects of Acetylsalicylic Acid on Free Radical Production in Cisplatin Induced Nephrotoxicity: An Experimental Rat Model

Cisplatin-induced nephrotoxicity is closely associated with an increase in lipid peroxidation. In several previous reports it was claimed that acetylsalicylic acid (ASA) shows its therapeutic potential as a free radical scavenger. The aim of the study was to investigate effects of ASA on cisplatin induced nephrotoxicity in an experimental rat model. Control animals (n:7) were administered 1 mL saline solution intraperitoneal (i.p.). Cisplatin group (n:7) was treated with a single dose of cisplatin i.p. (6 mg/kg), ASA group (n:7) was treated with i.p. (2.5 mg/kg) per day during the study, cisplatin plus ASA group (n:7) was administered single dose cisplatin i.p. (6 mg/kg) plus ASA (2.5 mg/kg) during 5 days. At the end of the study, Catalase (CAT), Glutathione Peroxidase (GSH-Px), Superoxide Dismutase (SOD), Nitric Oxide Synthase (NOS) enzymes activities and Malondialdehyde (MDA), Antioxidant Potential (AOP) levels were measured in both erythrocytes and renal tissues. Urea and creatinine levels and renal tissue necrosis in cisplatin plus ASA group were significantly lower than cisplatin group (p = 0.000, p = 0.014, p = 0.015). SODr activities and MDAr levels of cisplatin plus ASA group were also significantly lower than cisplatin group (p = 0.000, p = 0.029). These results show that cisplatin and ASA combination decreases the levels of urea and creatinine, reduces necrosis and improves antioxidant enzyme activities, MDA and AOP in rat kidney.

Erythrocyte nitric oxide metabolism in patients with chronic renal failure

AIMS

This study aims to investigate arginine-nitric oxide pathway in chronic renal failure (CRF) and to establish erythrocyte nitric oxide synthase (NOS) and arginase (ARG) activities in patients with CRF.

MATERIALS AND METHODS

NOS and ARG activities were measured in erythrocytes from 30 patients with CRF and 12-control subjects.

RESULTS

Erythrocyte NOS activity was found to be significantly lower and ARG activity higher in patients with CRF compared with controls. No differences were, however, found between patients with and without hemodialysis. A negative correlation (r = -0.7) was established between ARG and NOS activities in erythrocytes from patients.

CONCLUSIONS

Results suggest that erythrocyte NO production is diminished in patients with CRF, possibly due to decreased NOS and increased ARG activities.

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.

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.

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.

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.

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.

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.

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.

Mucosal antioxidant defense is not impaired in ulcerative colitis

BACKGROUND/AIMS

In this study, mucosal antioxidant defense was investigated in the biopsy samples from 12 patients with active ulcerative colitis and from 13 patients under remission.

METHODOLOGY

Biopsy samples obtained from healthy colon parts of the same subjects were used as control.

RESULTS

No changes were observed between superoxide dismutase, glutathione peroxidase and catalase enzyme activities of control or inflamed biopsy samples. However, antioxidant potential values were found to be higher and malondialdehyde levels lower in inflamed samples compared with controls.

CONCLUSIONS

Our results show that in contrast to previous suggestions, mucosal antioxidant defense is not impaired in ulcerative colitis.

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.

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.

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.

High-temperature effects on antioxidant systems and toxic product formation in nutritional oils

In this study, effects of high-temperature heating on antioxidant defense potential (AOP) and malondialdehyde (MDA) levels were investigated in several types of oils ingested by humans. Natural olive oil, refined olive oil, sunflower oil, and soy oil were examined. High-temperature heating to 180 degrees C significantly decreased AOP. This was accompanied by a significant increase in MDA levels. The observed changes were quantitatively greater in soy and sunflower oil compared to olive oil. The loss in antioxidant defense potential and elevation in peroxidation products may be associated with enhanced disease processes.

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.

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.

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.

Antioxidant potential of cancerous human kidney tissues

Antioxidant potentials (AOP) of cancerous and noncancerous adjacent human kidney tissues from 12 patients were measured. AOP of the cancerous tissues was found to be significantly lower than that of noncancerous ones. However, tissue malondialdehyde (MDA) levels were significantly higher in the cancerous tissues compared with noncancerous ones. In the intra-correlation analysis, carried out between AOP and MDA levels, significant correlation was found in the cancerous tissues (r = 0.9) but no correlation observed in the noncancerous ones. In the inter-correlation analysis, negative correlation was found between AOP's of cancerous and noncancerous tissues (r = -0.49) and positive correlation between MDA levels (r = 0.51). Results suggest that antioxidant potential of cancerous kidney tissues is significantly reduced compared with noncancerous ones. Therefore, they expose to high oxidant stress and free radical-induced peroxidative attacks, the results of which are cellular deformations.