Ravi Kiran

Oxidative stress in systemic lupus erythematosus: relationship to Th1 cytokine and disease activity.

Imbalance between oxidative stress and helper T-cell (Th1)-derived cytokines is one possible cause for the pathogenesis of systemic lupus erythematosus (SLE). To evaluate the correlation between oxidative stress and Th1 cytokine level with the disease activity of SLE in the North Indian population, oxidative/anti-oxidant profiles: malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione (GSH) and interferon (IFN)-gamma, interleukin (IL)-12 were studied. The estimation of oxidant and anti-oxidant enzymes was done in erythrocyte hemolysate and the levels of IFN-gamma and IL-12 were determined in the culture supernatant of peripheral blood mononuclear cells (PBMC) by a sandwich enzyme-linked immunosorbent assay (ELISA). A significant increase in the level of lipid peroxidation, measured as malondialdehyde (MDA), was found in SLE patients. The activities of anti-oxidant enzymes: SOD, CAT, GPx and anti-oxidant molecule GSH were significantly reduced in SLE patients as compared to controls. Increased levels of IFN-gamma and IL-12 were found in the culture supernatant of PBMC of SLE patients. MDA level was positively correlated with Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) score, IFN-gamma, IL-12 and negatively correlated with GSH in SLE patients. Strong positive correlations of IFN-gamma and MDA with SLEDAI score suggest that lipid peroxidation and pro-inflammatory cytokine, both are involved in the pathogenesis of SLE. Collectively, this study advocates that severity of disease might be enhanced by imbalance between oxidative stress and helper T-cell (Th1)-derived cytokines in SLE.

Effects on antioxidant status of liver following atrazine exposure and its attenuation by vitamin E

In the present investigation, the effect of atrazine on antioxidant enzymes and body weight was studied in male Wistar rats. Atrazine (300 mg/kgbw) was administered by gavage for 7, 14 and 21 days. A significant increase in hepatic lipid peroxidation (LPO) was observed following atrazine administration. Vitamin E treatment (100 mg/kgbw), on the otherhand, attenuated atrazine-induced LPO in liver. In addition, vitamin E treatment restored the GSH content and glucose-6-phosophate dehydrogenase activity that was found to be lowered after atrazine administration. The activities of antioxidant enzymes: superoxide dismutase, catalase, glutathione peroxidase and glutathione-s-transferase were significantly increased following atrazine administration and vitamin E treatment could restore these activities. In conclusion, the results of the study demonstrate that atrazine induces oxidative stress in terms of enhanced lipid peroxidation. However, vitamin E treatment ameliorated the effects of atrazine suggesting it as potential antioxidant against atrazine-induced oxidative stress.

Protective effects of vitamin E against atrazine-induced genotoxicity in rats

Atrazine (2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine) is one of the most commonly used herbicides to control grasses and weeds. The widespread contamination and persistence of atrazine residues in the environment has resulted in human exposure. Vitamin E is a primary antioxidant that plays an important role in protecting cells against toxicity by inactivating free radicals generated following pesticides exposure. The present study was undertaken to investigate the protective effect of vitamin E against atrazine-induced genotoxicity. Three different methods: gel electrophoresis, comet assay and micronucleus test were used to assess the atrazine-induced genotoxicity and to evaluate the protective effects of vitamin E. Atrazine was administered to male rats at a dose of 300 mg/kg body weight for a period of 7, 14 and 21 days. There was a significant increase (P<0.001) in tail length of comets from blood and liver cells treated with atrazine as compared to controls. Co-administration of vitamin E (100 mg/kg body weight) along with atrazine resulted in decrease in tail length of comets as compared to the group treated with atrazine alone. Micronucleus assay revealed a significant increase (P<0.001) in the frequency of micronucleated cells (MNCs) following atrazine administration. In the animals administrated vitamin E along with atrazine there was a significant decrease in percentage of micronuclei as compared to atrazine treated rats. The increase in frequency of micronuclei in liver cells and tail length of comets confirm genotoxicity induced by atrazine in blood and liver cells. In addition, the findings clearly demonstrate protective effect of vitamin E in attenuating atrazine-induced DNA damage.

N-Acetylcysteine ameliorates carbofuran- induced alterations in lipid composition and activity of membrane bound enzymes

The present work investigates the protective effects of N-acetylcysteine (NAC) on carbofuran-induced alterations in lipid composition and activity of membrane bound enzymes (Na+-K+-ATPase and Ca2+-ATPase) in the rat brain. Animals were exposed to carbofuran at a dose of 1 mg/kg body weight, orally, for a period of 28 days. A significant increase in lipid peroxidation in terms of TBARS was observed in brain after carbofuran exposure. NAC administration (200 mg/kg body weight) on the other hand lowered the carbofuran-induced lipid peroxidation to near normal. The increased lipid peroxidation following carbofuran exposure was accompanied by a significant decrease in the levels of total lipids, which is attributed to the reduction in phospholipid levels. Furthermore, NAC administration had a beneficial effect on carbofuran-induced alterations in lipid composition. The ratio of cholesterol to phospholipid, a major determinant of membrane fluidity, was increased in response to carbofuran exposure. This was associated with decreased activity of Na+-K+-ATPase and Ca2+-ATPase. NAC was observed to offer protection by restoring the cholesterol to phospholipid ratio along with the activity of Na+-K+-ATPase and Ca2+-ATPase. The results clearly suggest that carbofuran exerts its neurotoxic effects by increasing lipid peroxidation, altering lipid composition and activity of membrane bound enzymes. NAC administration ameliorated the effects of carbofuran suggesting its potential therapeutic effects in carbofuran neurotoxicity.

Association between T lymphocyte sub-sets apoptosis and peripheral blood mononuclear cells oxidative stress in systemic lupus erythematosus

Abstract Increased oxidative stress and lymphocyte apoptosis are a hallmark of the autoimmune disease systemic lupus erythematosus (SLE). However, the association between oxidative stress and T lymphocytes apoptosis has still to be elucidated in SLE. In order to appraise the interaction between oxidative stress and T lymphocyte apoptosis with the severity of disease, oxidative stress profile and T lymphocytes apoptosis were studied. Increased levels of ROS, MDA and CD4+ lymphocyte apoptosis were positively associated with disease activity while decreased levels of GSH and percentage expression of CD4+ lymphocyte were negatively associated with disease activity. The decrease in intracellular levels of GSH was negatively associated with T lymphocyte, CD4+ lymphocyte, CD8+ lymphocyte apoptosis and intracellular caspase-3 expression. The present study suggests that increased T lymphocyte sub-sets apoptosis may be mediated by decreased intracellular glutathione concentration and severity of disease might be enhanced together by over-production of ROS in SLE.

Atrazine-induced alterations in rat erythrocyte membranes: Ameliorating effect of vitamin E

Erythrocytes are a convenient model to understand oxidative damage to the membranes induced by various xenobiotics. The objective of the present study was to investigate the propensity of atrazine to induce oxidative stress and its possible attenuation by vitamin E. Experimental animals were orally administered atrazine (300 mg kg−1 body weight, daily) and vitamin E (100 mg kg−1 body weight, daily) for a period of 7, 14, and 21 days. Erythrocyte membranes were prepared and analyzed for acetylcholinesterase (AChE) activity, lipid peroxidation (LPO), and lipid composition. Susceptibility of erythrocytes to atrazine exposure was further investigated in terms of morphological alterations by scanning electron microscopy (SEM). Results indicate that atrazine exposure caused a significant inhibition of AChE activity and induction of oxidative stress in terms of increased malondialdehyde (MDA) levels. Atrazine treatment significantly decreased total lipid, cholesterol, and phospholipid content of erythrocyte membranes. SEM revealed varying degrees of distortion depending on duration of atrazine exposure. However, administration of vitamin E ameliorated the oxidative stress and changes in the erythrocyte membranes induced by atrazine.

Oxidative stress induced by atrazine in rat erythrocytes: mitigating effect of vitamin E.

The present study investigates the propensity of atrazine to induce oxidative stress and its possible attenuation by vitamin E in rat erythrocytes, which is a convenient model to understand the oxidative damage induced by various xenobiotics. Experimental animals were administered atrazine (300 mg/kg body weight, daily) and/or vitamin E (100 mg/kg body weight, daily) orally for a period of 7, 14, and 21 days. Results indicated that the reduced glutathione (GSH) content of the erythrocytes of atrazine treated rats was significantly decreased as compared to the control group. Co-administration of vitamin E along with atrazine restored the GSH content of erythrocytes nearly to control levels. The activities of antioxidant enzymes such as superoxide dismutase, catalase, glutathione peroxidase, and glutathione-s-transferase were found to be increased significantly in the erythrocytes accompanied by a decrease in the activity of the glucose-6-phosophate dehydrogenase, following atrazine exposure. On the other hand, when vitamin E was co-administered along with atrazine, activities of these enzymes were found to be restored significantly. In conclusion, results of the study demonstrated that atrazine induced oxidative stress in rat erythrocytes, in terms of increased activities of the various antioxidant enzymes, and decreased content of reduced glutathione. However, vitamin E administration ameliorated the effects of atrazine, suggesting that vitamin E is a potential antioxidant against atrazine-induced oxidative stress.

Role of Biomolecules from human renal stone matrix on COM crystal growth

Human renal calculi surgically removed from kidney stone patients were obtained and chemically analysed. Stones with CaOx (calcium oxalate) as the major component were washed in 0.15 M NaCl with gentle stirring for 48 h and then pulverised to a fine powder. The powder was extracted with 0.05 M EGTA, 1 mM PMSF and 1% β- mercaptoethanol for 4 days at 4°C, the suspensions and the supernatants obtained were filtered through an Amicon Model 200 apparatus (mol. wt. cut off of 10,000 daltons) under nitrogen at 40 p.s.i. and concentrated to a known volume. The method of Nakagawa et al. [7] was employed to study the ability of > 10 kDa fractions to influence COM growth using metastable solution of CaCl2 and Na2C2O2 containing traces of 14C-oxalic acid. Potent biomolecules having the ability to influence CaOx precipitation were subjected to isolation, purification and characterization. Standard biochemical procedures, e.g. ultracentrifugation, ion-exchange chromatography, molecular sieve chromatography and SDS-PAGE, etc., were employed. Results revealed that human renal calculi extract contains biomolecules that can inhibit as well as stimulate the growth of preformed COM (calcium oxalate monohydrate) crystals. Most potent stimulator of CaOx growth was found to have a molecular weight of 66 kDa.

BIOCHEMICAL STUDIES ON ENDOSULFAN TOXICITY IN DIFFERENT AGE GROUPS OF RATS

The effect of oral administration of endosulfan (12.5 mg/kg body weight), daily, for 4 days was investigated in female rats of 4 different age groups, i.e., 15, 30, 70, and 365 days old. Maximum hyperglycemia, maximum depletion of liver glycogen and maximum inhibition of brain acetylcholine esterase activity were observed in 365-day-old (adult) animals whereas these changes were found to be negligible in 15-day-old animals. A decrease in the activity of liver aldolase was observed in rats of all age groups but maximum decrease was observed in adult rats. In contrast to these changes, erythrocyte (Na+, K+)-ATPase was maximally inhibited in 15-day-old rats. These studies indicated that the toxic effects of endosulfan are age-dependent.

Modulation of dopaminergic system and neurobehavioral functions in delayed neuropathy induced by organophosphates.

Acute exposure to organophosphate pesticides (OPs) is associated with the development of a syndrome called organophosphate-induced delayed neuropathy (OPIDN) which is not mediated through hyper-cholinergic crisis. The present study has been designed to examine the role of alterations in dopaminergic system and neurobehavioral deficits in OPIDN. Rats were administered an acute dose of monocrotophos (MCP, 20 mg/kg body weight, orally) or dichlorvos (DDVP, 200 mg/kg body weight, subcutaneously), 15–20 min after treatment with antidotes (atropine (20 mg/kg body weight) and 2-pralidoxime (100 mg/kg body weight) intraperitoneally) to induce OPIDN. At biochemical level, an increase in dopamine, norepinephrine, and homovanillic acid levels were observed in brain of MCP- or DDVP-treated animals compared to controls. This was accompanied by increased intracellular calcium levels and lipid peroxidation in the cerebral cortex of OP-exposed animals. In addition, deficits in locomotor activity and spatial memory were observed in animals exposed to either MCP or DDVP. These results clearly suggest the role of dopaminergic system in memory and motor deficits observed in delayed neuropathy induced by OPs.