Effects of radiation on protein oxidation and lipid peroxidation in the brain tissue.

Radiation produces reactive oxygen species that modify macromolecules such as protein and lipid by oxidation and act in many pathological processes, causing serious damage to the brain. This study sought to evaluate the effects of radiation and the protective effect of N-acetylcysteine (NAC) on the brain tissue of guinea pigs based on the levels of lipid peroxidation and protein oxidation. Thirty-two guinea pigs were divided into groups of eight animals each: control group (group I); radiation group (group II); NAC group (group III), and NAC administered before radiation exposure group; (group IV). Guinea pigs in groups II and IV were exposed to Co(60) radiotherapy using the Source-Axis-Distance = 80 technique. The levels of protein carbonyl content and malondialdehyde (MDA), which is a marker for lipid peroxidation, were investigated by the Evans-Levine and Uchiyama-Mihara methods, respectively. The protein carbonyl and MDA levels of group II were significantly greater than those of group I (P < .01). The protein carbonyl and MDA levels of group IV were lower than those of group II. The difference between the MDA levels of group IV and group II was significant (P < .01); however, the difference in protein carbonyl levels between the two groups was not significant. The results indicated that radiation increased protein oxidation and lipid peroxidation in the brain, and NAC administration before radiation exposure may aid in the treatment by decreasing protein and lipid oxidation.

Changes in serum carbonyl and malondialdehyde levels following colchicine and vitamin E treatment in Behcet's disease.

Behcet's disease (BD) is an inflammatory disorder of an unknown cause, but growing evidence indicates that the oxidative stress is increased in BD, owing to the overproduction of reactive oxygen species (ROS) and decreased efficiency of antioxidant defenses. ROS affect proteins and lipids and cause their oxidation, therefore, contributing to the formation of oxidation products: carbonyl, a marker of protein oxidation, and malondialdehyde (MDA), a marker of lipid peroxidation. The investigation was undertaken to evaluate protein oxidation (carbonyl group) levels and lipid peroxidation (MDA) levels, and the role of colchicine and vitamin E therapy on protein carbonyl group and MDA levels in serum samples of patients with BD. In this study, subjects were classified as control group, colchicine therapy group alone and colchicine and vitamin E therapy group. Protein carbonyl and MDA levels at the beginning of the study were significantly (p < 0.05) higher in both therapy groups compared with those of the control group. We found that the protein carbonyl and MDA levels at the end of the study showed no significant (p > 0.05) differences between the therapy groups and control group. These results provide some evidence for a potential effect of colchicine and vitamin E therapies on increased protein oxidation and lipid peroxidation in BD.

Effects of static and 50 Hz alternating electric fields on superoxide dismutase activity and TBARS levels in guinea pigs.

The toxic oxygen free radicals are extremely reactive and can cause considerable damage to biomolecules, such as RNA, enzymes, membranes, proteins, and lipids, which may in turn lead to various pathological consequences. Lipid peroxidation, evaluated by determination of thiobarbituric acid reactive substances (TBARS) is the free radical-induced oxidation of polyunsaturated fatty acids. Normally, the oxygen free radicals are neutralized by highly efficient systems in the body. These include antioxidant enzymes like superoxide dismutase (SOD). In a healthy subject, there is a balance between free radicals and levels of antioxidants. The aim of this study was to determine lipid peroxidation and SOD levels in plasma, liver, lung and kidney tissues exposed to different intensities, directions and exposure periods of static and 50 Hz alternating electric fields. Electric field intensities ranging from 0.3 kV/m to 1.8 kV/m were applied in vertical or horizontal direction in exposure periods of 1, 3, 5, 7, and 10 days. The increase in SOD and TBARS levels of plasma, liver, lung, and kidney tissues was found to depend significantly on the type of electric field and the exposure period.

Assessment of protein oxidation in women using raloxifene.

OBJECTIVES: To assess the oxidative effects of raloxifene use in postmenopausal women by investigating protein carbonyl levels in the plasma. METHODS: Nineteen osteoporotic postmenopausal women treated with raloxifene for 12 months were included in the study. Another seventeen postmenopausal women matched for age and postmenopausal years, without any medication were chosen as a control group. Protein carbonyl levels were determined as oxidative stress markers by the use of Levine's method in the plasma of these women. RESULTS: Serum protein carbonyl levels of postmenopausal women treated with raloxifene (1.27 +/- 0.32 nmol/mg protein) were significantly lower than the control group (2.18 +/- 0.27 nmol/mg protein) (p < 0.05). CONCLUSIONS: Oxidative stress has been found responsible for several diseases including cancer. Protein carbonyl levels, which are the products of protein oxidation, are one of the indicators of oxidative stress. Therefore, the decline in protein carbonyl levels in this study revealed the decreasing oxidative stress. According to our results, it might be interpreted that raloxifene does not cause oxidative stress, and it may even have protective effects in long-term use.

Changes in zinc levels and superoxide dismutase activities in the skin of acute, ultraviolet-B-irradiated mice after treatment with ginkgo biloba extract.

Acute ultraviolet-B (UV-B) irradiation is known to act as an initiator in the formation of reactive oxygen species. These oxygen products are highly reactive and they are able to cause irreversible damage to cellular components. Oxygen free radicals are normally neutralized by very efficient systems in the body. These include antioxidant enzymes like superoxide dismutase (SOD). In a healthy subject, there is a balance between free radicals and the levels of antioxidants. In some pathological conditions such as oxidative stress, the level of antioxidants is significantly reduced. The skin contains relatively high levels of zinc (Zn), an essential element known to be a cofactor in some metabolic pathways. Zinc has also been reported to have antioxidant properties. In the present study, we investigated the effect of ginkgo biloba extract (Gbe), a potent free-radical scavenger, on UV-B-irradiated skin by measuring SOD activity and Zn levels in the skin, before and after treatment. The SOD activity was decreased after UV-B exposure, in comparison with the control group (p < 0.05). After Gbe treatment, the SOD activity increased (p < 0.05) as compared with the untreated UV-B irradiated group. The Zn levels changed in the same pattern as the SOD activity values.

Taurine and calcium interaction in protection of myocardium exposed to ischemic reperfusion injury.

We aimed to investigate the cardio-protective role of taurine with low calcium level against reperfusion damage by adding taurine to extracellular fluid. Guinea-pig hearts were mounted on Langendorf perfusion apparatus and different compositions of perfusion solutions were prepared for each experimental group. After 20 min of normothermic ischemia the hearts were reperfused. Pre-ischemic, post-ischemic and post-reperfusion percentage changes of heart rate and contractile force were compared. Post-reperfusion tissue weight, malondialdehyde (MDA) and prostaglandin E-like activity (PGE-like activity) were assessed. Taurine-added low-calcium perfusion solution significantly decreased the postischemic myocardial injury.

The effect of EGb 761 on the doxorubicin cardiomyopathy.

Doxorubicin (Dx) is used to treat a number of types of cancer. The drug produces many toxic reactions and cardiomyopathy. Many drugs have been used to prevent this myocardial damage caused by peroxidative alterations. EGb 761 is being used to prevent arrhythmias in ischemic myocardium. We decided to establish the tissue protective effect of EGb 761 against myocardial toxic effects of Dx in three groups of rats. Cardiotoxicity signs of Dx were found to be dose-related, beginning at 30 mg/kg dose and being apparent at 45 mg/kg dose. 48 hr after a single i.v. injection, myocardial tissues showed a marked edema, vacuolization and fragmentation. We compared the changes in heart tissue biochemically and histopathologically among the control, Dx treated and EGb 761 (100 mg/kg/d.x 4, i.p.) + Dx treated groups. Biochemical results of CK-MB and MDA values showed a significant decrease in Dx + EGb 761 group when compared with Dx treated group. Histopathologically, myocardial tissues of Dx + EGb 761 treated group were found to have diminished vacuolization and fragmentation. These results suggest that EGb 761 might have the same therapeutic potential in Dx related cardiomyopathy.

Changes in blood haemorheological parameters after submaximal exercise in trained and untrained subjects.

The blood stream is affected by viscosity and many other haemorheological factors such as lipid peroxidation in the plasma and red blood cells. The aim of this study was to investigate the changes of haemorheological parameters after submaximal exercise in trained and untrained subjects. The results indicated that heart rate, lymphocyte count, erythrocyte deformability, plasma lipid peroxide levels and erythrocyte glutathione peroxidase activity are increased after submaximal exercise.

Effects of EGF and allopurinol on prostaglandin and lipid peroxide levels in mucosa of stomach in restraint cold stress.

The cold and restraint gastric stress models were used in rats. Mucosal levels of prostaglandins, which have a protective effect on cells, and lipid peroxidation, a possible etiological factor in stress-induced gastric mucosal injuries, were investigated. Epidermal growth factor (EGF), which protects the gastric tissue from stress-induced lesions, and allopurinol, which inhibits xanthine oxidase, were given intraperitoneally. Both EGF and allopurinol decreased lipid peroxidation at the mucosal surface of the stomach. At the same time, allopurinol increased the serum gastrin levels and decreased the mucosal prostaglandin levels. It is concluded that EGF protects the gastric mucosal surface by way of increased tissue prostaglandin levels. EGF also decreased both serum gastrin and tissue malondialdehyde, an indicator of lipid peroxidation.

Antioxidative role of ocular melanin pigment in the model of lens induced uveitis.

Ocular melanin pigment has antioxidant effect against excess of dispersed light. To investigate whether it has a similar effect in ocular inflammations, we used albino and pigmented guinea pigs and measured retinal glutathione peroxidase activities and lipid peroxide levels (expressed as thiobarbituric acid reactive substances) in a model of lens induced uveitis. Although the increase in the levels of the retinal lipid peroxides were higher in the albino group (204%, p < 0.05), the decrease in the activities of glutathione peroxidase were higher in pigmented guinea pigs (26%, p < 0.005). The results of the study suggest that pigmentless animals are more sensitive to the ocular inflammations, and ocular melanin pigment may act as an endojen antioxidant in lens induced uveitis.

The effect of allopurinol on the liver ultrastructure, reduced glutathione and lipid peroxide levels during liver ischemia in guinea pigs.

1. The preventive effect of allopurinol on reduced glutathione and lipid peroxide levels of the liver and the accompanying ultrastructural changes during liver ischemia was investigated in guinea pigs. 2. Liver glutathione levels decreased significantly while lipid peroxide levels increased slightly in the ischemic group. 3. Allopurinol administered before ischemia resulted in a reverse significant increase in liver glutathione levels and a significant decrease in lipid peroxide levels indicating a protective effect upon cell membrane during ischemia. 4. On the other hand, electron microscopic changes in the liver associated with ischemia could not be altered by allopurinol.

The effect of deferoxamine on brain lipid peroxide levels and Na-K ATPase activity following experimental subarachnoid hemorrhage.

1. In the present study we have studied the effects of deferoxamine treatment on lipid peroxidation and Na-K ATPase activity after experimental induction of subarachnoid haemorrhage (SAH) in guinea pigs. 2. We assessed the extent of lipid peroxidation by measuring the level of malondialdehyde and Na-K ATPase activity in 3 different groups (sham-operated, SAH, SAH + deferoxamine). 3. There was no significant difference in lipid peroxide content between sham-operated and haemorrhagic animals, but Na-K ATPase activity decreased after SAH. 4. Deferoxamine treatment reduced the malondialdehyde content and induced the recovery of Na-K ATPase activity, exerting a brain protective role against the detrimental effects of the haemorrhage.

The effect of allopurinol on Na+K+ATPase related lipid peroxidation in ischemic and reperfused rabbit kidney.

1. Na+K+ATPase is a membrane bound enzyme whose activity is essential for maintenance of cell viability. Lipid peroxidation changes membrane fluidity and enzyme activity. 2. The purpose of this study was to investigate the effect of allopurinol (free radical scavenger) on Na+K+ATPase activity in rabbit kidney cortex membrane. In this in vivo study we created ischemia and reperfusion in rabbit kidneys. 3. Enzyme activity were low in ischemic and reperfused kidneys, compared to the controls. In allopurinol treated ischemic and reperfused groups, the levels of Na+K+ATPase activity were high compared to the untreated group. 4. It has been concluded that allopurinol may protect this enzyme activity.

The effect of EGb 761 on retinal lipid peroxidation and glutathione peroxidase level in experimental lens induced uveitis.

An acute lens-induced necrotizing intraocular inflammation was produced in pigmented guinea pigs. Treatment of these animals by 100 mg/kg/day EGb 761 a free oxygen radical scavenger for 10 days, reduced retinal lipid peroxidation (p > 0.05) and increased the retinal glutathione peroxidase level (p > 0.05). Although not significantly, these findings suggest that EGb 761 could be combined with other antiinflammatory drugs and may be beneficial in the treatment of uveitis.

The effects of taurine on perfused heart muscle malondialdehyde levels.

1. Taurine is found as a free amino acid in plasma and many tissues such as heart, muscle, brain and blood. Its exact role is not fully defined but it appears to have an important effect on the function of the heart. 2. The purpose of this study was to investigate the effects of taurine (10(-3) M and 10(-2) M) on malondialdehyde levels in perfused heart muscle. 3. In this study we found that administrated taurine before anoxia and reperfusion increased the malondialdehyde levels but administrated taurine after anoxia decreased the malondialdehyde levels in perfused heart muscle compared to the taurine administrated group before anoxia. 4. Anoxia did not change the perfused heart muscle malondialdehyde levels.

Effect of diethylnitrosamine on prostaglandin E and lipid peroxidation levels in rat's liver, lung and renal tissue.

We have investigated the generation of a prooxidant state and effect on prostaglandin E (PGE) levels after administration of diethylnitrosamine (DENA) to rats. Lipid peroxides were assayed by monitoring thiobarbituric acid (TBA) a reactive material. PGE--like activity was assayed by using bioassay procedure. Our results demonstrate that increased lipid peroxide and decreased PGE levels were found in a dose dependent manner in DENA injected groups when compared to control groups. According to these findings, it is suggested that there is a negative correlation between carcinogenic DENA induced lipid peroxidation and PGE in rat's liver, lung, and renal tissue.

Free radicals and antioxidant systems.

Free radicals are undesirable peroxides that have long been implicated in several deleterious effects in our body including aging process. They also play an important role in many physiological processes. For they are very reactive in nature, there are some anti-oxidant systems to scavenge or to quench them.

Na+,K(+)-ATPase activity of rabbit kidney cortex membranes in ischemia and reperfusion.

The activity of Na+,K(+)-ATPase in the microsomal fraction of rabbit kidney cortex was strongly decreased by ischemia and increased slightly, but not significantly, after reperfusion. These changes were correlated with a dramatic increase in lipid peroxidation in microsomes isolated from both ischemic and reperfused kidneys. This correlation may point to irreversible impairment of the enzymatic function under the influence of either oxygen free radicals or lipid peroxidation.

Effects of acute swimming exercise on muscle and erythrocyte malondialdehyde, serum myoglobin, and plasma ascorbic acid concentrations.

Acute exercise may induce free-radical production in mitochondria during basal metabolism of aerobic cells. Ascorbic acid is a strong antioxidant agent, whereas myoglobin is known to act as an oxygen reservoir. The purpose of this study was to investigate the effects of acute exercise on malondialdehyde levels in gastrocnemius, vastus medialis, and triceps brachi muscles and erythrocytes. In addition, we investigated the ascorbic acid levels and serum myoglobin concentrations in rats, following acute swimming exercise. We found that the levels of muscle malondialdehyde and serum myoglobin increased and the levels of plasma ascorbic acid decreased, in proportion to the duration of exercise; however, the levels of erythrocyte malondialdehyde did not change.

The effect of epidermal growth factor on liver lipid peroxidation and glutathione levels in lobectomized rats.

Epidermal growth factor (EGF) is a growth-promoting polypeptide which is found in highest levels in male mice in the submaxillary gland. It may also be a key factor in regeneration of the liver. We performed experiments with 18 male Wistar rats, divided into three groups. Hepatic left lobectomy (%30) was performed on the first group of rats. This group received an intraperitoneal injection of EGF for 7 days. The second group was the control group into which normal saline was injected for 7 days. The third group was sham-operated. On days 5 and 7 tomographic studies of liver were performed. On day 7 EGF levels, lipid peroxidation, and glutathione in liver were measured in all of the rats. While serum EGF levels did not show any significant change, the levels of lipid peroxide were decreased and glutathione was increased. Tomographic measurements indicated that administration of EGF increased the amount of regeneration.