Active Oxygen Damage Effect of Chlorophyll Degradation in Rice Seedlings Under Osmotic Stress

The changes of chlorophyll (Chl) content and contents of protochlorophyllide (Pchl), superoxide radical (O2-) and hydrogen peroxide (H2O2), malondialdehyde (MDA), ascorbic acid (ASA), glutathione (GSH), carotenoid (CAR) and the binding capacity of chlorophyll-protein (Chl-Pro) in rice (Oryza sativa L. ) seedlings exposed to osmotic stress induced by PEG 6000 (–0. 5 MPa, –0.8 MPa) were investigated to explore the relationship between Chl degradation and active oxygen effect. Under osmotic stress, Chl degradation was accompanied by the increase of contents of O2-, H2O2 and MDA and the decrease of contents of antioxidants AsA, GSH and CAR. The binding of Chl-Pro was loosened with the change of time and intensity of osmotic stress. Pretreatment with scavengers for active oxygen, such as AsA, α-tocopherol and mannitol retarded lipid peroxidation and reduced the oxidative injury of Chl, but Fe2+, H2O2 and Fenton reaction promoted the formation of MDA. The Fenton reaction accelerated the degradation of Chl. The results indicate that Chl degradation in rice seedlings induced by osmotic stress may be mainly due to the formation of more active hydroxyl radicals ('OH) through Fenton reaction and Haber-Weiss reaction.     

Protective effect of alpha-tocopherol on oxidative stress in experimental pulmonary fibrosis in rats

The study was undertaken to investigate the influence of alpha-tocopherol (vitamin E) on malondialdehyde (MDA) and glutathione (GSH) levels and catalase (CAT) activity in lung of rats with bleomycin-induced pulmonary fibrosis (PF). Fourteen Wistar-albino rats were randomly divided into two groups of seven animals each. The first group was treated intra-tracheally with bleomycin hydrochloride (BM group); the second group was also instilled with BM but received injections of alpha-tocopherol twice a week (BM + E group). The third group was treated in the same manner with saline solution only, acting as controls (C). There were decreases in GSH level and CAT activity while an increase in MDA level in BM group was found compared to the control group (p < 0.05). Vitamin E had a regulator effect on these parameters. After administration of alpha-tocopherol, the increase in GSH level and CAT activity and the decrease in MDA level were seen in BM + E group compared to BM group (p < 0.05). Distinct histopathological changes were found in the BM group compared to the untreated rats. Less severe fibrotic lesions were also observed in the BM + E group. The results show that vitamin E is effective on the prevention of BM-induced PF, as indicated by differences in the lung levels of oxidants and antioxidants.     

Intermittent hypobaric hypoxia-induced oxidative stress in rat erythrocytes: protective effects of vitamin E, vitamin C, and carnitine

This study was aimed at determining the effect of vitamin E, vitamin C, and carnitine on intermittent hypobaric-hypoxia-induced oxidative stress (OS) in erythrocytes. For this purpose, male Wistar rats of 4 months of age were orally supplemented with one of the antioxidants prior to exposure to altitudes of 5700 m or 6300 m. Hemoglobin (Hb) and OS indices such as osmotic fragility and hemolysis were measured together with lipid peroxidation (LPO) and protein oxidation. The increase in Hb was accompanied by increase in activities of antioxidant enzymes, superoxide dismutase (SOD), and catalase (CAT) during exposure to both the altitudes without any further elevation by supplements. The extent of reduction in osmotic fragility and hemolysis by vitamin E and carnitine was greater at 6300 m than at 5700 m. Increase in LPO products, for example, malondialdehyde (MDA) and lipofuscin-like autofluorescent substances (AFS) was noticeable at both the altitudes, and vitamin E and carnitine were effective in reducing LPO. While protein oxidation products such as carbonyl content (PrC) and advanced oxidation protein products (AOPP) increased at 6300 m, protein sulphydryl (P-SH) content decreased. P-SH levels were restored on supplementation of antioxidants. Hence, our results indicate that vitamin E, vitamin C, and carnitine may be beneficial in overcoming OS and hemolysis under situations such as intermittent hypobaric hypoxia (IHH) and hypobarotherapy wherein hypoxia is used to correct many pathological situations in humans. Further, this study suggests that supplementation of vitamin E, vitamin C, and L-carnitine alone and not in combination can be beneficial in attenuating the OS associated with IHH compared to the unsupplemented rats exposed to two different altitudes.     

The use of ELISA to monitor amplified hemolysis by the combined action of osmotic stress and radiation: potential applications

A new assay has been developed to study the osmotic fragility of red blood cells (RBCs) and the involvement of oxygen-derived free radicals and other oxidant species in causing human red blood cell hemolysis. The amount of hemoglobin released into the supernatant, which is a measure of human red blood cell hemolysis, is monitored using an ELISA reader. This ELISA-based osmotic fragility test compared well with the established osmotic fragility test, with the added advantage of significantly reduced time and the requirement of only 60 mul of blood. This small amount of blood was collected fresh by finger puncture and was immediately diluted 50 times with PBS, thus eliminating the use of anticoagulants and the subsequent washings. Since exposure of RBCs to 400 Gy gamma radiation caused less than 5% hemolysis 24 h after irradiation, the RBC hemolysis induced by gamma radiation was amplified by irradiating the cell in hypotonic saline. The method was validated by examining the protective effect of Trolox, an analog of vitamin E and reduced glutathione (GSH), a well-known radioprotector, against human RBC hemolysis caused by the combined action of radiation and osmotic stress. Trolox, a known membrane stabilizer and an antioxidant, and GSH offered significant protection. This new method, which is simple and requires significantly less time and fewer RBCs, may offer the ability to study the effects of antioxidants and membrane stabilizers on human red blood cell hemolysis induced by radiation and oxidative stress and assess the osmotic fragility of erythrocytes.     

Effect of vitamin C and zinc on osmotic fragility and lipid peroxidation in zinc-deficient haemodialysis patients

Peroxidation of the membrane lipid structure of red blood cell leads to haemolysis and anaemia in haemodialysis patients. Dietary constituents of antioxidant vitamins and trace elements may play an important role in protecting against oxidant damage. In this study, the effects of supplementation of vitamin C and zinc on osmotic fragility and lipid peroxidation of erythrocytes were investigated in 34 zinc-deficient haemodialysis patients. Sixteen sex- and age-matched normal volunteers acted as controls. Patients were randomized to receive vitamin C (250 mg day(-1)), zinc (20 mg day(-1)) or a placebo treatment for 3 months. The levels of vitamin C, zinc, malondialdehyde (MDA) and osmotic fragility were measured initially and 3 months after supplementation. Mean serum concentration of vitamin C and zinc increased significantly in the groups at the end of the respective study periods. Supplementation with vitamin C and zinc improved osmotic fragility, and decreased the level of MDA in the groups, but some side-effects (i.e. nausea, vomiting, fever, muscle pain, weakness) were observed during the zinc treatment. The results showed that the supplementation of both treatments decreased osmotic fragilty and MDA in zinc-deficient haemodialysis patients. However, vitamin C treatment was found to be safer than zinc supplementation.     

Antioxidant Status and Susceptibility of Sickle Erythrocytes to Oxidative and Osmotic Stress

The purpose of this study was to determine if differences in antioxidant status between the red blood cells (RBCs) of sickle cell anemia (SCA) patients and controls are responsible for the differential responses to oxidative and osmotic stress-induced hemolysis. Susceptibility to hemolysis was examined by incubating oxygenated and deoxygenated RBCs at 37°C with 73 mM 2,2' azobis (2-amidinopropane) HC1 (AAPH), a peroxyl radical generator, for up to 3.5 hours. The ability of RBCs to maintain membrane integrity under osmotic stress was determined over a range of diluted saline-phosphate buffer. Sickled RBCs showed a lesser degree of AAPH-induced hemolysis than control groups and were more resistant to osmotic stress-induced hemolysis. SCA patients had higher levels of RBC vitamin E and RBC lipids, but lower RBC GSH, plasma lipids and plasma carotenes than those of the hospital controls. No significant differences were observed in the levels of retinol, vitamin C, vitamin E, MDA and conjugated dienes in plasma, or the levels of MDA and conjugated dienes in RBCs. The results obtained suggest that the differences in antioxidant status between sickled RBCs and controls do not appear to be responsible for their different susceptibility to oxidative or osmotic stress-induced hemolysis observed.     

Absent effect of zinc deficiency on the oxidative stress of erythrocytes in chronic uremic rats

Both anemia and zinc deficiency are commonly observed in patients with chronic uremia. Oxidative stress of red blood cells (RBC) has been suggested to participate in the development of anemia in these patients with chronic uremia due to reduced life span of RBC. Whether zinc deficiency aggravates the effect of oxidative stress on RBC of chronic uremia is still not understood. We thus performed the study to determine the influence of zinc deficiency on the oxidative stress of RBC in uremic rats. Zinc deficiency was induced by long-term dietary zinc deficiency. Five-sixth nephrectomy (5/6 Nx) was used to produce chronic uremia. Experiment was carried out in the following five groups: normal control (NL), chronic uremia (Nx), chronic uremia + dietary zinc deficiency (Nx-D), Nx-D + zinc supplement (Nx-DZ) and Chronic uremia + pair-fed (Nx-PF). Osmotic fragility and lipid peroxidation of RBC were used to evaluate the oxidative stress of RBC. Five weeks after 5/6 nephrectomy (Nx), 5/6 Nx rats present a syndrome of uremia to elevate the levels of plasma creatinine and urea, and reduce the level of plasma zinc (1.12 +/- 0.08 vs 1.35 +/- 0.05 ug/ml). But they does not find to produce anemia and to increase osmotic fragility and lipid peroxidation in RBC. Dietary zinc deficiency in Nx-D group produced severe anorexia and reduced plasma zinc and selenium levels and the activity of RBC-GPX. Yet in Nx-D rats, osmotic fragility and susceptibility of lipid peroxidation in red cells did not increase, because of the increase of plasma copper level (1.85 +/- 0.3 vs 1.41 +/- 0.05 microg/ml) and RBC-SOD activity (1.95 +/- 0.27 vs 0.78 +/- 0.05 unit/g Hb). Zinc supplement in Nx-D rats (Nx-DZ group) recovered the appetite and normalized the levels of plasma zinc, copper and selenium. Food restriction in 5/6 Nx rats (Nx-PF group) decreased plasma copper level and increased osmotic fragility of RBC and elevated the susceptibility of lipid peroxidation after stressing RBC with H2O2 Because Nx-PF rats presented a lower RBC-SOD activity (0.44 +/- 0.11 vs 0.78 +/- 0.05 unit/g Hb) and a lower plasma copper level. We further found a positive relationship (r=0. 802,p<0.01) between plasma copper level and RBC-SOD activity in normal and uremic rats. This study suggests that RBC-SOD activity may play an important role in preventing RBC oxidative stress. Plasma copper level may be a marker of RBC-SOD activity. We conclude, in chronic uremia, zinc deficiency doses not result in RBC oxidative stress as plasma copper level is normal, but may affect the absorption of intestinal nutrition.     

17β-Estradiol and Vitamin E Modulates Oxidative Stress-Induced Kidney Toxicity in Diabetic Ovariectomized Rat

The aim of this study was to investigate the effects of vitamin E (alpha-tocopherol) and 17β-estradiol (E(2)) supplementation on malondialdehyde (MDA), glutathione (GSH), vitamin A, beta carotene, selenium-dependent glutathione peroxidase (GSH-Px), zinc-dependent superoxide dismutase (SOD), and copper/zinc-dependent catalase (CAT) values in the kidney of ovariectomized (OVX) diabetic rats. Forty-two female rats were randomly divided into seven equal groups as follows: group I, control; group II, OVX; group III, OVX+E(2); group IV, OVX+E(2)+alpha-tocopherol; group V, OVX+diabetic; group VI, OVX+diabetic+E(2); and group VII, OVX+diabetic+E(2)+alpha-tocopherol. E(2) (40?μg?kg(-1)/day) and alpha-tocopherol (100?μg?kg(-1)/day) were given. Bilateral ovariectomy was performed in all groups except group I. After 4?weeks, antioxidant and MDA levels in the kidney for all groups were analyzed. GSH-Px, CAT, SOD, GSH levels, vitamin A, and beta carotene levels were decreased in OVX group compared to those in the control group but MDA level was elevated via ovariectomy. However, E(2) and E(2)+alpha-tocopherol supplementations in OVX group was associated with an increase in the GSH-Px, GSH, CAT and Zn-SOD values, vitamin A, and beta carotene levels but a decrease in MDA levels in kidney. The MDA levels in the kidney of diabetic OVX rats were found higher than those in the control and OVX groups. However, GSH, GSH-Px, CAT, SOD, vitamin A, and beta carotene levels in kidney were lower in OVX diabetic rats. On the other hand, E(2) and E(2)+alpha-tocopherol supplementations to OVX diabetic rats have caused an increase in GSH-Px, CAT and SOD, GSH, vitamin A, and beta carotene levels but a decrease in MDA levels. In conclusion, the E(2) and E(2)+alpha-tocopherol supplementations to diabetic OVX and OVX rats may strengthen the antioxidant defense system by reducing lipid peroxidation, and therefore they may play a role in preventing renal disorders.     

Lithium-Induced Hypothyroidism: Oxidative Stress and Osmotic Fragility Status in Rats

The present study was conducted to explore the possible effects of different doses of lithium carbonate on thyroid functions, erythrocyte oxidant–antioxidant status, and osmotic fragility. Twenty-four Wistar-type male rats were equally divided into three groups: groups I and II received 0.1 and0.2 % lithium carbonate in their drinking water, respectively, for 30 days. The rats in group III served as controls, drinking tap water without added lithium. At the end of the experimental period, the erythrocyte osmotic fragility and the levels of triiodothyronine (T₃), thyroxine (T₄), thyroid-stimulating hormone (TSH), malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione (GSH) were measured in blood samples. Compared to controls, there was a statistically significant increase of TSH but decreases of the T₃ and T₄ levels in group II. Both experimental groups showed a statistically significant increase of the maximum osmotic fragility limit. The minimum osmotic fragility values of the animals in group II were statistically higher than those of controls. The standard hemolytic increment curve of both experimental groups was shifted to the right when compared to the curve obtained from the controls. Also, relative to controls, the activities of MDA and SOD were significantly higher and the GSH level lower in group II, but not so in group I. The results of the present study show that treatment with lithium carbonate may result in thyroid function abnormalities, increased oxidative damage, and possible compromise of the erythrocyte membrane integrity resulting from increased osmotic fragility.     

Effect of vitamin E on the degradation of hydrogen peroxide in cultured human umbilical vein endothelial cells

Vitamin E reacts with radicals such as lipid peroxyl radical (LOO*) and singlet oxygen ((1)O2), and plays a role in inhibiting lipid peroxidation in cell membranes and preventing the oxidation of low-density lipoproteins (LDL). However, only a few studies have investigated the effect of vitamin E on the degradation of hydrogen peroxide (H2O2). Therefore, we examined the effect of vitamin E on glutathione redox cycle-dependent H2O2 degradation activity in human umbilical vein endothelial cells (HUVEC). Confluent HUVEC were cultured for seven days in media containing various concentrations of vitamin E (alpha-tocopherol). The level of glutathione redox cycle-dependent H2O2 degradation activity and the intracellular glutathione level were determined. HUVEC that had been cultured in the presence of higher concentrations of vitamin E had a higher level of H2O2 degradation activity and a higher intracellular content of the reduced form of glutathione (GSH). Therefore, it is suggested that the vitamin E-induced increase in H2O2 degradation activity in HUVEC results from an increase in intracellular GSH level.     

Trypanosoma evansi: Effect of experimental infection on the osmotic fragility, lipid peroxidation and calcium-ATPase activity of rat red blood cells

Trypanosoma evansi is the causative agent of equine trypanosomoses. The disease is characterized by fever, anemia, and cachexia. Peroxidative damage of the red blood cells caused by the parasite, may contribute to the pathogenesis of the anemia seen in trypanosomoses. Consequently, we evaluated the hematocrit, the osmotic fragility of the red blood cells, the level of lipid peroxidation and the activity of the Ca-ATPase of red blood cell ghosts from rats experimentally infected with T. evansi. After 72 h inoculation, the hematocrit decreased from 49.5% to 33%; the osmotic fragility of the red blood cells was approximately 40% higher as compared to the healthy animals; and the red blood cell ghosts showed a higher level of lipid peroxidation and a lower Ca-ATPase activity than the red cell ghosts from the healthy animals. In vitro incubations of red blood cells from healthy animals with T. evansi, produced also a significant increase of the osmotic fragility of the red blood cells.     

Efficacy of piperine, an alkaloidal constituent from Piper nigrum on erythrocyte antioxidant status in high fat diet and antithyroid drug induced hyperlipidemic rats

The main aim of this study was to investigate the effect of piperine on erythrocyte antioxidant status in high fat diet (HFD) and antithyroid drug induced hyperlipidemic rats. Male Wistar rats were divided into eight groups. The first four groups were fed a control diet and in addition were given respectively 1% carboxymethyl cellulose (CMC); 10 mg/kg body weight carbimazole (CM); 10 mg CM + 40 mg/kg body weight piperine and 10 mg CM + 2 mg/kg body weight atorvastatin (ATV). A similar pattern was followed for the next four groups except that they were all fed HFD instead of the control diet. Erythrocyte osmotic fragility, total cholesterol, phospholipids, lipid peroxidation products, enzymic and non-enzymic antioxidant status were studied in all experimental groups. Significantly increased osmotic fragility, total cholesterol/phospholipid ratio, thiobarbituric acid reactive substances and lipid hydroperoxides were observed in the plasma and erythrocytes of HFD fed and CM treated rats compared to the control. Superoxide dismutase, catalase, glutathione peroxidase, vitamin E and reduced glutathione in erythrocytes and vitamin C in the plasma were also significantly lowered in HFD fed, antithyroid drug treated rats compared to control animals. Concurrent piperine supplementation along with HFD and antithyroid drug administration normalized erythrocyte osmotic fragility, reduced lipid peroxidation, and improved the enzymic and non-enzymic antioxidant status compared to those rats that did not receive piperine. Thus, our results indicate that piperine supplementation markedly protects erythrocytes from oxidative stress by improving the antioxidant status in HFD fed antithyroid drug treated rats.     

The influence of dietary selenium and vitamin E on glutathione peroxidase and glutathione in the rat

The effect of dietary selenium (Se) and vitamin E supplementation on tissue reduced glutathione (GSH) and glutathione peroxidase activity has been studied in the rat. Increasing Se intake by 0.4 ppm gave significantly higher enzyme levels in all tissues studied, an effect not influenced by vitamin E intake. Further increasing Se to 4 ppm gave higher enzyme levels in red blood cells only, while in liver was there was a significant decrease in enzyme activity probably reflecting Se hepatotoxicity. In the absence of Se supplements increasing dietary vitamin E to 100 mg/kg diet significantly increased enzyme activity but this effect was modified by simultaneous Se supplementation.Se intake had no effect on GSH levels. Rats on high vitamin E intake 500 mg/kg had a significantly higher tissue GSH level. Dietary Se had a sparing effect on vitamin E, rats supplemented with Se having significantly raised plasma vitamin E levels.These results confirm the role of selenium in glutathione peroxidase and also show that vitamin E influences the activity of the enzyme.     

Enhanced testicular antioxidant capacity in streptozotocin-induced diabetic rats: protective role of vitamins C and E and selenium

Diabetes mellitus is associated with diabetic impairment of testicular function, ultimately leading to reduced fertility. Its etiology may involve oxidative damage by reactive oxygen substances, and protection against this damage can be offered by antioxidant supplementation. The aim of this study was to investigate the effects of intraperitoneal administration of vitamin C and E, selenium (Se), and vitamin E plus Se (COM) on concentrations of lipid peroxide (as malondialdehyde; MDA), reduced glutathione (GSH), and vitamin E concentrations and glutathione peroxidase (GSH-Px) activity in the testes of rats with diabetes induced by streptozotocin (STZ). Sixty groups were used (10 animals each) and these animals were initially allocated to two groups: control group and diabetic group. The diabetic group was subdivided into five groups as follows: diabetic control (DC), vitamin E, Se, COM, and vitamin C. Animals in the DC group and vitamin C, vitamin E, Se, and COM groups were made diabetic by the injection of STZ on 4 d after an injection of vitamins C and E, Se, and COM. Those vitamins and Se were also administered for 21 consecutive days. The MDA, vitamin E, GSH levels, and GSH-Px activities in testes were determined. Although the vitamin E concentration was higher in the control than in the DC group, the MDA levels were found to be lower in the control than in the DC group. The MDA levels in the testes samples of vitamin C, vitamin E, Se, and COM groups were lower than the DC group. However, GSH-Px activity and GSH levels in the testes were not significantly different between the control and DC groups. Vitamin E concentrations in the vitamin C, vitamin E, Se, and COM groups and GSH levels and GSH-Px activities in the Se, COM, and vitamin C groups were higher than either the control or DC group. The results indicate that reactive oxygen substances may be involved in possible testicular complications in diabetes of rats. Administration of vitamins C and E and Se reduced the testicular lipid peroxidation; these vitamins and Se had significant protective effects on testes of rats against oxidative damage in diabetes.     

Exercise-induced oxidative stress affects erythrocytes in sedentary rats but not exercise-trained rats.

Oxidant stress is one of the factors proposed to be responsible for damaged erythrocytes observed during and after exercise. The impact of exertional oxidant stress after acute exhaustive treadmill running on erythrocyte damage was investigated in sedentary (Sed) and exercise-trained (ET) rats treated with or without antioxidant vitamins C and E. Exhaustive exercise led to statistically significant increments in the levels of thiobarbituric acid-reactive substance (TBARS) and H2O2-induced TBARS in Sed rats and resulted in functional and structural alterations in erythrocytes (plasma hemoglobin concentrations, methemoglobin levels, and rise in osmotic fragility of erythrocytes with decrease in erythrocyte deformability). Administration of antioxidant vitamin for 1 mo before exhaustive exercises prevented lipid peroxidation (TBARS, H2O2-induced TBARS) in Sed rats without any functional or structural alterations in erythrocytes. Parameters indicating erythrocyte lipid peroxidation and deterioration after exhaustive exercise in rats trained regularly with treadmill running for 1 mo were not different from those in Sed controls. Erythrocyte lipid peroxidation (TBARS) increased in exhausted-ET rats compared with ET controls; however, the plasma hemoglobin, methemoglobin levels, and erythrocyte osmotic fragility and deformability did not differ. Exhaustive exercise-induced lipid peroxidation in ET rats on antioxidant vitamin treatment was prevented, whereas functional and structural parameters of erythrocytes were not different from those of the ET controls. We conclude that exertional oxidant stress contributed to erythrocyte deterioration due to exercise in Sed but not in ET rats.     

Vitamin E supplementation and glutathione peroxidase activity.

Both excess dietary vitamin E and vitamin E deficiency in rats can significantly depress the activity of GSH peroxidase in liver and plasma of rats. Of all the six levels of vitamin E tested in this study, the dietary level of vitamin E found to maintain the maximum activity of GSH peroxidase in tissues of rats was somewhere between 25 and 250 IU/kg diet. This study conclusively indicates that the excess dietary vitamin E represses GSH peroxidase activity.     

Enhanced testicular antioxidant capacity in streptozotocin-induced diabetic rats

Diabetes mellitus is associated with diabetic impairment of testicular function, ultimately leading to reduced fertility. Its etiology may involve oxidative damage by reactive oxygen substances, and protection against this damage can be offered by antioxidant supplementation. The aim of this study was to investigate the effects of intraperitoneal administration of vitamin C and E, selenium (Se), and vitamin E plus Se (COM) on concentrations of lipid peroxide (as malondialdehyde; MDA), reduced glutathione (GSH), and vitamin E concentrations and glutathione peroxidase (GSH-Px) activity in the testes of rats with diabetes induced by streptozotocin (STZ). Sixty groups were used (10 animals each) and these animals were initially allocated to two groups: control group and diabetic group. The diabetic group was subdivided into five groups as follows: diabetic control (DC), vitamin E, Se, COM, and vitamin C. Animals in the DC group and vitamin C, vitamin E, Se, and COM groups were made diabetic by the injection of STZ on 4 d after an injection of vitamins C and E, Se, and COM. Those vitamins and Se were also administered for 21 consecutive days. The MDA, vitamin E, GSH levels, and GSH-Px activities in testes were determined. Although the vitamin E concentration was higher in the control than in the DC group, the MDA levels were found to be lower in the control than in the DC group. The MDA levels in the testes samples of vitamin C, vitamin E, Se, and COM groups were lower than the DC group. However, GSH-Px activity and GSH levels in the testes were not significantly different between the control and DC groups. Vitamin E concentrations in the vitamin C, vitamin E, Se, and COM groups and GSH levels and GSH-Px activities in the Se, COM, and vitamin C groups were higher than either the control or DC group. The results indicate that reactive oxygen substances may be involved in possible testicular complications in diabetes of rats. Administration of vitamins C and E and Se reduced the testicular lipid peroxidation; these vitamins and Se had significant protective effects on testes of rats against oxidative damage in diabetes. Abstract of the study was presented at the conference Trace Elements in Men and Animals-11. June 2–6, 2002; Dr. Naziroğlu has been awarded a TEMA11 Investigative Scientist Award.     

渗透胁迫对杧果叶片活性氧伤害的影响

杧果叶片经渗透胁迫处理后,叶水势Ψ_L下降,O₂^·产生速率和MDA含量增加,SOD、POD和CAT的活性水平与O₂^·和MDA的变化相一致。结果表明,杧果叶片的渗透胁迫损伤,是由O₂^·引发的膜脂过氧化,致使MDA含量增加,破坏细胞膜系统所致。渗透胁迫处理过程中,GSH和AsA含量下降。     

Vitamin C and vitamin E restore the resistance of GSH-depleted lens cells to H2O2

A decline in reduced glutathione (GSH) levels is associated with aging and many age-related diseases. The objective of this study was to determine whether other antioxidants can compensate for GSH depletion in protection against oxidative insults. Rabbit lens epithelial cells were depleted of > 75% of intracellular GSH by 25-200 microM buthionine sulfoximine (BSO). Depletion of GSH by BSO alone had little direct effect on cell viability, but resulted in an approximately 30-fold increase in susceptibility to H(2)O(2)-induced cell death. Experimentally enhanced levels of nonprotein sulfhydryls other than GSH (i.e., N-acetylcysteine) did not protect GSH-depleted cells from H(2)O(2)-induced cell death. In contrast, pretreatment of cells with vitamin C (25-50 microM) or vitamin E (5-40 microM), restored the resistance of GSH-depleted cells to H(2)O(2). However, concentrations of vitamin C > 400 microM and vitamin E > 80 microM enhanced the toxic effect of H(2)O(2). Although levels of GSH actually decreased by 10-20% in cells supplemented with vitamin C or vitamin E, the protective effects of vitamin C and vitamin E on BSO-treated cells were associated with significant ( approximately 70%) decreases in oxidized glutathione (GSSG) and concomitant restoration of the cellular redox status (as indicated by GSH:GSSG ratio) to levels detected in cells not treated with BSO. These results demonstrate a role for vitamin C and vitamin E in maintaining glutathione in its reduced form. The ability of vitamin C and vitamin E in compensations for GSH depletion to protect against H(2)O(2)-induced cell death suggests that GSH, vitamin C, and vitamin E have common targets in their actions against oxidative damage, and supports the preventive or therapeutic use of vitamin C and E to combat age- and pathology-associated declines in GSH. Moreover, levels of these nutrients must be optimized to achieve the maximal benefit.     

Chronic depletion of glutathione (GSH) and minimal modification of LDL in vivo: its prevention by glutathione mono ester (GME) therapy

A decline in reduced glutathione (GSH) level is associated with aging and free radical mediated diseases. The objective of this study was to determine whether the chronic depletion of extra cellular GSH causes oxidative damage to the circulating macromolecules such as lipoproteins. Decreased concentrations of plasma glutathione, vitamin E and ascorbic acid were recorded in the rats treated with buthionine sulfoximine (BSO), a selective GSH inhibitor. In LDL isolated from BSO-treated animals, the concentration of malondialdehyde (MDA) and conjugated dienes were significantly increased (P<0.01), whereas the levels of vitamin E were decreased (P<0.01). The analysis of total and LDL cholesterol revealed significant changes between the control and experimental groups. Of interest, altered concentrations of lyso-phosphatidyl choline (Lyso-PC) and phosphatidyl choline (PC) were recorded from the BSO mediated minimally modified LDL. A negative correlation between LDL-BDC/MDA and its antioxidant capacity was noted. Upon in vitro oxidation with CuSO(4), the electrophoretic behavior of purified LDL-apoprotein-B on agarose gel showed an increased mobility in BSO-treated rats, indicative of in vivo modification of LDL to become susceptible for in vitro oxidation. The increased mobility of LDL (after in vitro oxidation) isolated from the BSO-treated animals correlates with a decrease in its amino groups, as determined by the trinitrobenzene sulfonic acid (TNBS) reactants. However, the mobility of LDL molecule was not altered due to BSO treatment in vivo. Interestingly, the minimal modification on LDL does not lead to any vascular damage in the dorsal aorta of the rats injected with BSO. The administration of glutathione monoester (GME), at a dose of 5 mmol/kg body weight, twice a day, for 30 days, to animals treated with l-buthionine-SR-sulfoximine (BSO, 4 mmol/kg body weight, twice a day, for 30 days) normalized the antioxidant status and prevented the minimal modifications on LDL. Thus, increasing the cellular GSH levels may trigger beneficial effects against oxidative stress.