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Abstract: Fish inhabiting polluted estuaries are highly exposed to severe stress characterized by an oxidant–antioxidant imbalance. The aim of the study was to explore the use of stress parameters such as adenosine triphosphate/adenosine diphosphate (ATP/ADP) ratio, mitochondrial membrane potential (∆ψm) and total protein expression patterns as biomarkers against oxidant exposures in hepatocytes of Mugil cephalus living in either a contaminated (Test; Ennore) or uncontaminated (Control; Kovalam) estuary. Earlier, the pollutant stress impact was determined through light and electron microscopy studies. The ATP/ADP ratio was measured using high performance liquid chromatography; ∆ψm by fluorescent probe 5, 5′, 6, 6′-tetrachloro-1, 1′, 3, 3′-tetraethyl benzimidazolcarbocyanine iodide (JC-1) dye and total protein expression patterns by protein profiling. The preponderance of stress impact was confirmed through microscopy studies that featured cytological alterations, disturbances in the surface morphology and in the cell organelles at the ultrastructural levels. Hepatocytes of test fish demonstrated a decrease in ATP and an increase in ADP and thereby alteration in ATP/ADP ratio (p <0.05; 20.75%). A significant disturbance (p <0.05; 26.57%) in ∆ψm with a ratio of J-aggregates/JC-1 monomer of 1 was observed for test fish hepatocytes compared to control group with a J-aggregates/JC-1 monomer ratio of 1.5. Quantitative assessment of protein expression levels also revealed enhanced induction of both low and high molecular weight proteins in test fish hepatocytes. The findings highlight the use of these parameters as the highly sensitive biomarkers in response to contaminant exposure compared to the routinely used antioxidant and oxidant stress parameters in biomonitoring programs. Among the measured parameters, the determination of ∆ψm may be suggested as a novel candidate as a biomarker because of its greater specificity and rapid quantitative risk assessment of pollutant exposures. [Copyright &y& Elsevier]

Abstract: Induction of antioxidant proteins like thioredoxin (Trx) and heat shock protein 90α (HSP90α) is a crucial step in the cellular response to oxidative stress. Here, we report the impact of environmental stress on Trx and HSP90α expressions in freshly isolated hepatocytes of Mugil cephalus living in either a contaminated (Test; Ennore) or uncontaminated (Control; Kovalam) estuary. Modulation in the activities of signal transduction molecules like apoptosis signal-regulating kinase 1 (ASK1) and c-Jun NH2-terminal kinase 1/2 (JNK1/2) were also investigated to understand their functional role under natural stressed condition. The expression pattern of the proteins was determined by immunoblotting and the relationship between the proteins was identified by regression analysis. Test fish hepatocytes demonstrated significant upregulation (P <0.05) in the levels of Trx and HSP90α and insignificant inductions in the expression pattern of ASK1 and JNK1/2 than control fish hepatocytes. These findings provide direct evidence that Trx and HSP90α induction in fish hepatocytes under stress may aid cell survival by negatively regulating ASK1 expression and thereby functionally antagonizing the apoptotic role of JNK1/2 in natural aquatic systems. [Copyright &y& Elsevier]

Background: Evidence is accumulating that mitochondrial (Mt) oxidative stress plays a role in the pathogenesis of preeclampsia. The current study analyzes the stress levels, energy status and associated enzymatic alteration in placental mitochondria of preeclamptic (n=30) and normotensive (n=35) subjects. Methods: Total Mt stress was measured using dichlorofluorescin (DCFH) oxidant analysis, malondialdehyde (MDA) concentrations, protein carbonyl (PC) concentrations and measurement of nitrite (NO2−) and nitrate (NO3−). Activity of antioxidant enzymes including superoxide dismutase (SOD), glutathione peroxidase (GPx) and the glutathione redox ratio (GRR) were measured. The ATP/ADP (adenosine triphosphate/adenosine diphosphate) concentrations and respiratory chain enzyme activities were also analyzed. The expression of heat shock protein 70 (HSP70) was measured in mitochondria. Results: The DCFH oxidants, MDA, PC concentrations, and concentrations of NO2− and NO3− were significantly higher in the preeclamptic group (p<0.01) compared with the control group. The activities of SOD, GPx, GRR [glutathione (GSH)/glutathione disulfate (GSSG)] (p<0.01, p<0.001), ATP/ADP and respiratory chain enzyme activities were reduced significantly (p<0.001) in preeclamptic conditions. The placental mitochondrial HSP70 (mtHSP70) showed significant over expression in the preeclamptic group (p<0.001) compared with the control group. Conclusions: These results provide the first line of evidence for accumulated Mt stress demonstrated by increased stress markers, decreased antioxidants and enhanced mtHSP70. The study illustrates the probable protective mechanism of mtHSP70 against the generated stress. This is primarily to combat the enzymatic and free radical mediated damage produced in preeclampsia. Clin Chem Lab Med 2009;47:1073–80. [ABSTRACT FROM AUTHOR]

The antioxidant properties of plants could be correlated with oxidative stress defence in different human diseases. The present study was undertaken to evaluate and compare the antioxidant potential and the phytochemical composition in the aqueous extracts of mint leaves, black tea and black tea enriched with mint extract. All the three preparations exhibited free radical-scavenging potential for nitric oxide (NO) radical, superoxide anion radical and hydroxyl radical, and the values were lesser than those of the antioxidants which acted as standards. In comparison, the mint extract exhibited higher free radical and NO scavenging effect. Hydroxyl radical and superoxide scavenging effects were more pronounced in tea with the mint extract, while the reducing power was exhibited more significantly by the black tea extract. The phytochemical compounds were identified and the total phenols and flavonoids were quantified and compared between these extracts. [ABSTRACT FROM AUTHOR]

Aims: Preeclampsia is a hypertensive disorder of human pregnancy and a leading cause of premature delivery and fetal growth retardation. The purpose of this study was to evaluate the expression of heat shock protein 70 (HSP70), both constitutive (HSC70) and induced (HSP70) forms, along with oxidative stress status in the placental tissues of normotensive (control group) and preeclamptic pregnancies. Materials and Methods: Placental samples were collected after delivery from normotensive pregnancies and preeclamptic patients (n = 20, each). Lipid peroxidation product malondialdehyde (MDA) and nitrite and nitrate levels, along with antioxidants such as superoxide dismutase (SOD) and glutathione peroxidase (GPx) and glutathione were estimated in the placental homogenate to evaluate the oxidative stress. Results: Placental tissue MDA levels and concentrations of nitrite and nitrate were significantly higher in the preeclamptic group (P < 0.001) than the control group. Placental SOD and GPx activities and the reduced glutathione (GSH)/oxidized glutathione (GSSG) ratio were significantly lowered in the preeclamptic (P < 0.001) group than the control group. Both placental HSC70 and HSP70 were in significantly higher concentrations in the preeclamptic (7.25 ± 0.76, 27.67 ± 2.32 ng/mg protein; P < 0.001) than the control (5.23 ± 0.64, 17.47 ± 1.22 ng/mg protein) group, respectively. Conclusions: The above data provide the first evidence that high levels of HSP70 are associated in the placenta of pre-eclamptic women. This enhanced expression is probably to exhibit its multiple protective effects on the cell's response to stress. [ABSTRACT FROM AUTHOR]