Role of glutathione in augmenting the anticancer activity of pyrroloquinoline quinone (PQQ)

Abstract

Pyrroloquinoline quinone (PQQ), a bacterial redox co-factor and antioxidant, is highly reactive with nucleophilic compounds present in biological fluids. PQQ induced apoptosis in human promonocytic leukemia U937 cells and this was accompanied by depletion of the major cellular antioxidant glutathione and increase in intracellular reactive oxygen species (ROS). Treatment with glutathione (GSH) or N-acetyl-L-cysteine (NAC) did not spare PQQ toxicity but resulted in a 2–5-fold increase in PQQ-induced apoptosis in U937 cells. Cellular GSH levels increased following treatment by NAC alone but were severely depleted by co-treatment with NAC and PQQ. This was accompanied by an increase in intracellular ROS. Alternatively, depletion of glutathione also resulted in increased PQQ cytotoxicity. However, the cells underwent necrosis as evidenced by dual labeling with annexin V and propidium iodide. PQQ-induced cytotoxicity is thus critically regulated by the cellular redox status. An increase in GSH can augment apoptosis and its depletion can switch the mode of cell death to necrosis in the presence of PQQ. Our data suggest that modulation of intracellular GSH can be used as an effective strategy to potentiate cytotoxicity of quinones like PQQ.     

Redox status in workers occupationally exposed to long-term low levels of ionizing radiation: A pilot study

Objectives: Reactive oxygen species (ROS), including superoxide (O₂^??), play an important role in the biological effects of ionizing radiation. The human body has developed different antioxidant systems to defend against excessive levels of ROS. The aim of the present study is to investigate the redox status changes in the blood of radiologic technologists and compare these changes to control individuals.

Methods: We enrolled 60 medical workers: 20 occupationally exposed to ionizing radiation (all radiologic technologists), divided in three subgroups: conventional radiography (CR), computerized tomography (CT), and interventional radiography (IR) and 40 age- and gender-matched unexposed controls. Levels of O₂^?? and malondialdehyde (MDA) in blood were measured as an index of redox status, as were the activities of antioxidant enzymes superoxide dismutase (SOD) and catalase. Redox status was also assessed by measuring levels of reduced and oxidized glutathione (GSH, GSSG, respectively).

Results: Levels of O₂^?? and MDA, and SOD activity in the blood of IR and CT-exposed subjects were significantly higher than both the CR-exposed subjects and control individuals. However, there were no statistically significant differences in the levels of catalase, GSH and ratio of GSH/GSSG between exposed workers and control individuals.

Discussion: This study suggests that healthcare workers in CT and IR occupationally exposed to radiation have an elevated circulating redox status as compared to unexposed individuals.     

Hydrogen treatment reduces tendon adhesion and inflammatory response

A rat model of tendon repair was established to investigate the effects of hydrogen water on tendon adhesion reduction. Thirty-six Sprague Dawley rats were randomly divided into a normal saline (NS) group and a hydrogen water (HS) group according to the processing reagents after a tendon repairing operation. Pre- and postoperative superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione (GSH) in subjects’ serum were observed. Skin fibroblasts were grouped into an NS group, H₂O₂ group, H₂ group, and H₂O₂ H₂ group. Expressions of Nrf2, CATA, and γ-GCS were also tested by Western blot analysis. 8-OHdG, GSH, MDA, and SOD of the cells were analyzed by the enzyme-linked immunosorbent assay method. The postoperative SOD activity and GSH contents were significantly reduced (P < 0.05), whereas the postoperative MDA level was significantly increased (P < 0.05). Similarly, the postoperative HS group showed significantly higher SOD activity and GSH contents (P < 0.05) but lower MDA (P < 0.05) compared with the postoperative NS group. MDA and 8-OHdG were significantly decreased in hydrogen-rich medium, while SOD and GSH were increased. The expression of Nrf2, CATA, and γ-GCS in antioxidant system were reduced after H₂O₂ processing, which were restored after the application of hydrogen-rich medium. Hydrogen water can reduce tendon adhesion after tendon repairing and prohibit excessive inflammatory response, which could be associated with the activation of the Nrf2 pathway.     

Prooxidant and cytotoxic action of N-acetylcysteine and glutathione in combinations with vitamin B12b

Prooxidant and cytotoxic effects of thiols N-acetylcysteine (NAC) and glutathione (GSH) were studied in combinations with vitamin B_12b. Both GSH and NAC at physiological doses when combined with B_12b were shown to cause initiation of apoptosis. It was established that the prooxidant action of NAC (or GSH) combined with B_12b, i.e., generation and accumulation of hydrogen peroxide in culture medium, led to intractellular oxidative stress and cell redox imbalance. These effects are completely prevented by nonthiol antioxidants catalase and pyruvate. The chelators of iron phenanthroline and deferoxamine do not suppress the H₂O₂ accumulation in culture medium, but inhibit cell death induced by NAC combined with B_12b or by GSH combined with B_12b. Therefore, the thiols GSH or NAC in combination with vitamin B_12b reveal prooxidant properties and induce, with participation of intracellular iron, apoptotic HEp-2 cell death.     

In Vitro Coinfection and Replication of Classical Swine Fever Virus and Porcine Circovirus Type 2 in PK15 Cells

Increasing clinical lines of evidence have shown the coinfection/superinfection of porcine circovirus type 2 (PCV2) and classical swine fever virus (CSFV). Here, we investigated whether PCV2 and CSFV could infect the same cell productively by constructing an in vitro coinfection model. Our results indicated that PCV2-free PK15 cells but not ST cells were more sensitive to PCV2, and the PK15 cell line could stably harbor replicating CSFV (PK15-CSFV cells) with a high infection rate. Confocal and super-resolution microscopic analysis showed that PCV2 and CSFV colocalized in the same PK15-CSFV cell, and the CSFV E2 protein translocated from the cytoplasm to the nucleus in PK15-CSFV cells infected with PCV2. Moreover, PCV2-CSFV dual-positive cells increased gradually in PK15-CSFV cells in a PCV2 dose-dependent manner. In PK15-CSFV cells, PCV2 replicated well, and the production of PCV2 progeny was not influenced by CSFV infection. However, CSFV reproduction decreased in a PCV2 dose-dependent manner. In addition, cellular apoptosis was not strengthened in PK15-CSFV cells infected with PCV2 in comparison with PCV2-infected PK15 cells. Moreover, using this coinfection model we further demonstrated PCV2-induced apoptosis might contribute to the impairment of CSFV HCLV strain replication in coinfected cells. Taken together, our results demonstrate for the first time the coinfection/superinfection of PCV2 and CSFV within the same cell, providing an in vitro model to facilitate further investigation of the underlying mechanism of CSFV and PCV2 coinfection.     

Pycnogenol enhances endothelial cell antioxidant defenses

Summary

Reactive oxygen species (ROS) such as hydrogen peroxide (H₂O₂), superoxide anion (O₂^?), and hydroxyl radical (OH^?) have been implicated in mediating various pathological events such as cancer, atherosclerosis, diabetes, ischemia, inflammatory diseases, and the aging process. The glutathione (GSH) redox cycle and antioxidant enzymes—superoxide dismutase (SOD) and catalase (CAT)—play an important role in scavenging ROS and preventing cell injury. Pycnogenol has been shown to protect endothelial cells against oxidant-induced injury. The present study determined the effects of pycnogenol on cellular metabolism of H₂O₂ and O₂^? and on glutathione-dependent and -independent antioxidant enzymes in bovine pulmonary artery endothelial cells (PAEC). Confluent monolayers of PAEC were incubated with pycnogenol, and oxidative stress was triggered by hypoxanthine and xanthine oxidase or H₂O₂. Pycnogenol caused a concentration-dependent enhancement of H₂O₂ and O₂^? clearance. It increased the intracellular GSH content and the activities of GSH peroxidase and GSH disulfide reductase. It also increased the activities of SOD and CAT. The results suggest that pycnogenol promotes a protective antioxidant state by upregulating important enzymatic and nonenzymatic oxidant scavenging systems.     

Can we reduce oxidative stress with liver transplantation?

BackgroundThe aim of this study was to determine the levels of lipid peroxidation (MDA) and antioxidants such as reduced glutathione (GSH), catalase (CAT) and superoxide dismutase (SOD) in the blood serum of patients with cirrhosis and liver transplantation.MethodsIn this study, serum malondialdehyde acid (MDA) levels, superoxide dismutase (SOD), reduced glutathione (GSH), and catalase (CAT) activities were measured spectrophotometrically and compared to the results of the healthy control group.ResultsSOD, CAT and GSH activities were significantly decreased in the patient groups compared to the healthy control group (p<0.05). MDA levels were significantly higher in the patient group compared to the healthy control group (p <0.05).ConclusionsIn conclusion, this study demonstrated that oxidative stress may play an important role in the development of liver cirrhosis and in liver transplantation. This study is the first one to show how MDA, SOD, CAT and GSH levels change in liver cirrhosis and liver transplantation, while further studies are essential to investigate antioxidant enzymes and oxidative stress status in patients with cirrhosis and liver transplantation.     

Spermidine pretreatment enhances heat tolerance in rice seedlings through modulating antioxidative and glyoxalase systems

This study was undertaken to investigate the possible involvement of the antioxidant defense and glyoxalase systems in protecting rice seedlings from heat-induced damage in the presence of spermidine (Spd). Hydroponically grown 14-day-old seedlings were subjected to foliar spray with Spd (1 mM, 24 h) prior to heat stress (42 °C, 48 h) followed by subsequent recovery (27 °C, 48 h). Lipoxygenase activity, malondialdehyde (MDA), hydrogen peroxide (H₂O₂) and proline (Pro) content increased significantly whereas fresh weight (FW) and chlorophyll (Chl) content decreased during heat stress and after recovery, indicating unrecoverable damage to rice seedlings. Heat-induced damage was also evident in decreased levels of ascorbate (AsA), glutathione (GSH), and AsA and GSH redox ratios. Superoxide dismutase (SOD) and catalase (CAT) activities increased during heat stress but declined after recovery. Activities of glutathione peroxidase (GPX), ascorbate peroxidase (APX), monodehydroascorbate reductase, dehydroascorbate reductase (DHAR) and glutathione reductase (GR) decreased during heat stress but an opposite trend for most of these enzymes was observed after recovery. Heat stress also resulted in significant increases in the activities of glyoxalase enzymes (Gly I and Gly II). In contrast, exogenous Spd protected rice seedlings from heat-induced damage as marked by lower levels of MDA, H₂O₂, and Pro content coupled with increased levels of AsA, GSH, FW, Chl, and AsA and GSH redox status. After recovery, Spd-pretreated heat-exposed seedlings displayed higher activities of SOD, CAT, GPX, GST APX, DHAR and GR as well as of Gly I and Gly II. In addition, polyamine analysis revealed that exogenously applied Spd significantly elevated the levels of free and soluble conjugated Spd. Therefore, we conclude from our results that heat exposure provoked an oxidative burden while enhancement of the antioxidative and glyoxalase systems by Spd rendered rice seedlings more tolerant to heat stress. Further, co-induction of the antioxidative and glyoxalase systems was closely associated with Spd mediated enhanced level of GSH.     

Acrylamide induces mitochondrial dysfunction and apoptosis in BV-2 microglial cells

Acrylamide (ACR), a potent neurotoxin, can be produced during food processing at high temperature. This study examined the redox-dependent apoptotic and inflammatory responses of ACR in an immortalized mouse microglia cell line BV2. The exposure of BV2 cells to ACR reduced cell viability and induced apoptosis in a concentration-dependent manner. ACR impaired cell energy metabolism by decreasing mitochondrial respiration, anaerobic glycolysis, and lowering expression of the complex I, III, and IV subunits. Mitochondrial dysfunction was associated with a decrease of the mitochondrial membrane potential and the Bcl-2/Bax ratio, thus resulting in activation of the mitochondrion-driven apoptotic signaling. This was accompanied by (a) the modulation of redox-sensitive signaling, suppressed Akt activation and increased JNK and p38 activation, and (b) increased expression of NFκB and downstream inducible nitric oxide synthase (iNOS) and nitric oxide generation, thus supporting indirectly a proinflammatory effect of ACR. Nrf2 expression was also increased but not its translocation to the nucleus. Expectedly, the electrophilic attack of ACR on GSH resulted in substantial loss of GSH with a minor GSSG formation. These changes in the cell׳s redox status elicited by ACR resulted in increased H₂O₂ formation. The changes in mitochondrial functionality and complex subunit expression caused by ACR were reversed by N-acetyl-L-cysteine (NAC). Likewise, NAC restored the cell׳s redox status by increasing GSH levels with concomitant attenuation of H₂O₂ generation; these effects resulted in decreased apoptotic cell death and inflammatory responses. ACR-mediated mitochondrial dysfunction along with a more oxidized redox status seems to be critical events leading to activation of the intrinsic apoptotic pathway and inflammatory responses.     

Select cyclopentenone prostaglandins trigger glutathione efflux and the role of ABCG2 transport

Electrophilic cyclopentenone prostaglandins (cyPGs), such as 15-deoxy-Δ^12,14-prostaglandin J₂ (15dPGJ₂), initiate redox-based cell signaling responses including increased intracellular glutathione (GSH) synthesis. We investigated whether cyPGs facilitated GSH efflux and if members of the ATP-binding cassette (ABC) protein family mediated the efflux. Four human cell lines were treated with 1–6 μM cyPGs for 48 h. Media and cells were harvested for GSH measurements using HPLC-EC. CyPG treatment increased extracellular GSH levels two- to threefold over controls in HN4 and C38 cells and five- to sixfold in SAEC and MDA 1586 cells and was dependent on increased GSH synthesis. Our studies show that prostaglandin D₂ and its metabolites, prostaglandin J₂ and 15dPGJ₂, specifically induce GSH efflux compared to other eicosanoids. These higher extracellular GSH levels were associated with protection from tert-butylhydroperoxide. Superarray analysis of ABC transporters suggested only ABCG2 expression had a positive relationship in the four cell types compared with extracellular GSH increases after cyPG treatment. The ABCG2 substrate Hoechst 33342 inhibited extracellular GSH increase after 15dPGJ₂ treatment. We report for the first time that ABCG2 may play a role in GSH efflux in response to cyPG treatment and may link inflammatory signaling with antioxidant adaptive responses.     

Glutathione oxidation correlates with one-lung ventilation time and PO2/FiO2 ratio during pulmonary lobectomy

Objectives: During lung lobectomy, the operated lung completely collapses with simultaneous hypoxic pulmonary vasoconstriction, followed by expansion and reperfusion. Here, we investigated glutathione oxidation and lipoperoxidation in patients undergoing lung lobectomy, during one-lung ventilation (OLV) and after resuming two-lung ventilation (TLV), and examined the relationship with OLV duration.

Methods: We performed a single-centre, observational, prospective study in 32 patients undergoing lung lobectomy. Blood samples were collected at five time-points: T0, pre-operatively; T1, during OLV, 5 minutes before resuming TLV; and T2, T3, and T4, respectively, 5, 60, and 180 minutes after resuming TLV. Samples were tested for reduced glutathione (GSH), oxidized glutathione (GSSG), glutathione redox potential, and malondialdehyde (MDA).

Results: GSSG and MDA blood levels increased at T1, and increased further at T2. OLV duration directly correlated with marker levels at T1 and T2. Blood levels of GSH and glutathione redox potential decreased at T1?T3. GSSG, oxidized glutathione/total glutathione ratio, and MDA levels were inversely correlated with arterial blood PO₂/FiO₂ at T1 and T2.

Discussion: During lung lobectomy and OLV, glutathione oxidation, and lipoperoxidation marker blood levels increase, with further increases after resuming TLV. Oxidative stress degree was directly correlated with OLV duration, and inversely correlated with arterial blood PO₂/FiO₂.     

Comparison of intracellular glutathione and related antioxidant enzymes: Impact of two glycosylated whey hydrolysates

The effects of two glycosylated whey hydrolysates (GWH-Gal A and GWH-Gal B) on glutathione (GSH) and related antioxidant enzymes in SGC-7901 cells were evaluated. Two whey glycosylated hydrolysates promoted an increase in reduced glutathione (GSH) in normal SGC-7901 cells. GSH, glutathione peroxidase (GPx), γ-glutamine cysteine synthetaase (γ-GCS), and catalase (CAT) at 1.0 and 2.0 mg/mL in normal SGC-7901 cells were higher in the GWH-Gal A group than in the GWH-Gal B group (P < 0.05). Compared with GWH-Gal B, GWH-Gal A more strongly inhibited decreases in intracellular GSH, GPx, γ-GCS, CAT, and superoxide dismutase (SOD) in H₂O₂-induced SGC-7901 cells. Compared with GWH-Gal B, GWH-Gal A at 1.0 and 2.0 mg/mL effectively inhibited increases in lactate dehydrogenase (LDH) and malondialdehyde (MDA) in H₂O₂-induced SGC-7901 cells (P < 0.05). Therefore, GSH content and related antioxidant enzyme activity levels (GPx, γ-GCS, CAT, SOD) in both normal and H₂O₂-induced SGC-7901 cells were considerably stronger in the GWH-Gal A group than in the GWH-Gal B group.     

Suppression of arsenic trioxide-induced apoptosis in HeLa cells by N-acetylcysteine

Arsenic trioxide (ATO) can affect many biological functions such as apoptosis and differentiation in various cells. We investigated the involvement of ROS and GSH in ATO-induced HeLa cell death using ROS scavengers, especially N-acetylcysteine (NAC). ATO increased intracellular O(2)(*-) levels and reduced intracellular GSH content. The ROS scavengers, Tempol, Tiron and Trimetazidine, did not significantly reduce levels of ROS or GSH depletion in ATO-treated HeLa cells. Nor did they reduce the apoptosis induced by ATO. In contrast, treatment with NAC reduced ROS levels and GSH depletion in the ATO-treated HeLa cells and prevented ATO-induced apoptosis. Treatment with exogenous SOD and catalase reduced the depletion of GSH content in ATO-treated cells. Catalase strongly protected the cells from ATO-induced apoptosis. In addition, treatment with SOD, catalase and NAC slightly inhibited the G1 phase accumulation induced by ATO. In conclusion, NAC protects HeLa cells from apoptosis induced by ATO by up-regulating intracellular GSH content and partially reducing the production of O(2)(*-).     

Ozone alleviates ischemia/reperfusion injury by inhibiting mitochondrion‐mediated apoptosis pathway in SH‐SY5Y cells

Cerebral ischemia/reperfusion (I/R) injuries are common and often cause severe complications. Ozone has been applied for protecting I/R injury in animal models of several organs including cerebra, but the detailed mechanism remains unclear. 3‐(4,5‐Dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay and lactate dehydrogenase measurement were used to determine the influence of ozone on cell activity and damage of SH‐SY5Y cells. Some redox items such as catalase (CAT), malondialdehyde (MDA), glutathione peroxidase (GSH‐Px), and superoxide dismutase (SOD) were measured by enzyme‐linked immunosorbent assay. The mitochondrial membrane potential (ΔΨ_m) was determined by JC‐1 assay. Cytochrome‐c (cyt‐c) level in the cytoplasm and mitochondrion was measured by western blotting. Apoptosis was determined by flow cytometry, and some apoptosis‐related molecules were detected by quantitative real‐time polymerase chain reaction and western blotting. Ozone alleviated oxidative damage by increasing GSH‐Px, SOD, CAT, and decreasing MDA. Ozone decreased mitochondrial damage caused by I/R injury and inhibited the release of cyt‐c from mitochondrion to cytoplasm in SH‐SY5Y cells. The cell apoptosis caused by I/R was inhibited by ozone, and ozone could decrease apoptosis by increasing the ratio of Bcl‐2/Bax and inhibiting caspase signaling pathway in SH‐SY5Y cells. Ozone has the ability of maintaining redox homeostasis, decreasing mitochondrion damage, and inhibiting neurocytes apoptosis induced by I/R. Therefore, ozone may be a promising protective strategy against cerebral I/R injury.     

The Role of Intracellular Glutathione in Inorganic Mercury-Induced Toxicity in Neuroblastoma Cells

It is well known that antioxidants containing sulfhydryl (−SH) groups are protective against the toxic effects of mercury. The current study was designed to elucidate the mechanism(s) of the cytoprotective effects of glutathione (GSH) and N-acetylcysteine (NAC) against the toxicity of inorganic mercury (HgCl₂) in neuroblastoma cells (N-2A). The obtained results demonstrated the protective effects of these compounds in a dose dependant manner up to 95 and 74% cell viability, respectively as compared to the control of HgCl₂ of 10%. The administration of buthionine sulfoximine (BSO), an inhibitor of GSH synthesis, increased the toxicity of HgCl₂ in a dose dependent manner. Moreover, BSO treatment attenuated the levels of the cellular free −SH concentrations at low concentrations (1–100 μM) of HgCl₂. The data also show that cellular thiol concentrations were augmented in the presence of GSH and NAC and these compounds were cytoprotective against HgCl₂ and this is due to up regulating of GSH synthesis. A reduction in intracellular levels of GSH was observed with treatment of HgCl₂. In addition, the ratio of GSH/GSSG increased from 16:1 to 50:1 from 1 to 10 μM concentration of HgCl_2. The ratio of GSH/GSSG then decreased from 4:1 to 0.5:1 with the increase of concentration of HgCl₂ between 100 μM and 1 mM due to the collapse of the N-2A cells. It was of interest to note that the synthesis of GSH was stimulated in cells exposed to low concentration of HgCl₂ when extra GSH is available. These data support the idea that the loss of GSH plays a contributing role to the toxic effects of HgCl₂ and that inorganic mercury adversely affects viability, through altering intracellular −SH concentrations. The data further indicate that the availability of GSH to the cells may not be sufficient to provide protection against mercury toxicity and the de novo synthesis of intracellular GSH is required to prevent the damaging effects of mercury.     

Alterations of the glutathione redox cycle status in fumonisin B1-treated pig kidney cells

Fumonisin B₁ (FB₁) causes equine leukoencephalomalacia, porcine pulmonary edema, and liver tumors and chronic nephritis in rats. To investigate mechanisms by which FB₁ induces toxicity, effects of FB₁ on cellular glutathione (GSH) redox status and GSH depletion on FB₁ toxicity in pig kidney (LLC-PK₁) cells were studied. Treatment of LLC-PK₁ cells with 50 μM FB₁ for 24 hours significantly decreased cellular GSH contents from 56 ± 3.2 to 42.7 ± 4.4 nmol/mg protein (p < 0.05) and increased the activities of glutathione reductase (GR) from 25.7 ± 2.4 to 35.7 ± 5.0 μmol NADPH/mg protein (p < 0.05). The activities of glutathione peroxidase (GSHpx), catalase, and Cu,Zn-superoxide dismutase (SOD) were not changed by this treatment. Treatment of LLC-PK₁ cells for 12 hours with 0.1. mM buthionine sulfoximine (BSO), a selective inhibitor of the enzyme γ-glutamylcysteine synthetase that catalyzes the rate-limiting reaction in de novo GSH synthesis, decreased cellular GSH levels to about 20% of that found in the control cells. The cells pretreated with 0.1 mM BSO for 12 hours were significantly sensitized to the FB₁ cytotoxicity as determined by a long-term survival assay (p < 0.05). The results demonstrate that FB₁ changes GSH redox cycle status in LLC-PK₁ cells, and GSH may play a role in cytoprotection against FB₁ toxicity. © 1997 John Wiley & Sons, Inc.     

Proline and functioning of the antioxidant system in Thellungiella salsuginea plants and cultured cells subjected to oxidative stress

The effects of proline on the functioning of antioxidant enzymes — superoxide dismutase (SOD) and ascorbate peroxidase (APO) — in Thellungiella salsuginea plants and cultured cells under normal conditions of culturing and under the influence of hydrogen peroxide (500 μM) were studied. Proline addition (0.2, 2, or 5 mM) to the medium for suspension culture or nutrient medium for plant growing resulted in the increase in the content of intracellular proline in both cultured cells and intact plant leaves and also in the activation of proline dehydrogenase, i.e., the enzyme degrading proline. Under normal conditions, treatment with proline exerted prooxidant action on both cellular and organismal levels. This was manifested in MDA accumulation and changes in APO and SOD activities. The amino acid alanine, used as a control, did not exert similar strong effect as proline. Application of 500 μM H₂O₂ on plant leaves resulted in the development of oxidative stress, whereas hydrogen peroxide addition into the culture medium — to the death of 50% of suspension cells. When plants and cultured cells were treated with 2 mM proline and than with H₂O₂, the number of dead cells in suspension was 35%, the content of MDA was decreased, APO was activated, and SOD activity was decreased in both cell culture and plant leaves. Thus, an increase in the intracellular proline concentration changed the redox balance and induced functioning of APO and SOD at both normal conditions of plant growing and cell culturing and under stress.     

Effect of cadmium on lipid peroxidation and activities of antioxidant enzymes in growing pigs

Malondialdehyde (MDA), glutathione (GSH) content, total antioxidant capacity (T-AOC) levels, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and glutathione transferase (GST) activities were studied in serum, liver, and kidney of growing pigs after graded doses of cadmium administration in diets. One hundred ninety-two barrows (Duroc x Landrace x Yorkshire), with similar initial body weight 27.67±1.33 kg, were randomly allotted into 4 different treatments with 3 replications (16 pigs per replication). The treatments received the same basal diet added with 0, 0.5, 5.0, and 10.0 mg/kg cadmium (as CdCl₂), respectively. The results showed pigs treated with 10 mg/kg cadmium significantly decreased average daily gain (ADG) (p<0.05) and increased feed/gain ratio (F/G) (p<0.05) compared to the control. In this treatment, the contents of MDA increased significantly (p<0.05), GSH concentrations, T-AOC levels, and the activities of SOD, GSH-PX, and GST decreased significantly (p<0.05). The results indicate 10 mg/kg cadmium could decrease pig antioxidant capacity after extended exposure and cadmium-induced increase lipid peroxidation might not be only the result of the possibility of lower level of GSH but could also be as a result of direct action of cadmium on peroxidation reaction.     

Effects of N-acetyl-l-cysteine on bleomycin induced oxidative stress in malignant testicular germ cell tumors

Testicular cancer is a very common cancer in males aged 15–44 years. Bleomycin is used in chemotherapy regimens in the treatment of patients having testicular germ-cell tumor. Bleomycin generates oxygen radicals, induces oxidative cleavage of DNA strand and induces apoptosis in cancer cells. There is no study in the literature investigating effects of N-Acetyl-l-Cysteine (NAC) on bleomycin-induced oxidative stress in testicular germ cell tumors. For this reason, we studied effects of NAC on oxidative stress produced in wild-type NTera-2 and p53-mutant NCCIT testis cancer cells incubated with bleomycin and compared the results with H₂O₂ which directly produces oxidative stress. We determined protein carbonyl content, thiobarbituric acid reactive substances (TBARS), glutathione (GSH), 8-isoprostane, lipid hydroperoxide levels and total antioxidant capacity in both testicular cancer cells. Bleomycin and H₂O₂ significantly increased 8-isoprostane, TBARS, protein carbonyl and lipid hydroperoxide levels in NTera-2 and NCCIT cells. Bleomycin and H₂O₂ significantly decreased antioxidant capacity and GSH levels in both cell lines. Co-incubation with NAC significantly decreased lipid hydroperoxide, 8-isoprostane, protein carbonyl content and TBARS levels increased by bleomycin and H₂O₂. NAC enhanced GSH levels and antioxidant capacity in the NTera-2 and NCCIT cells. It can be concluded that NAC diminishes oxidative stress in human testicular cancer cells induced by bleomycin and H₂O₂.