Free radicals and other active derivatives of oxygen are inevitable by-products of biological redox reactions. Reactive oxygen species inactivate enzymes and damage important cellular components. The increased production of toxic oxygen derivatives is considered to be a universal or common feature of stress conditions. Plant and other organisms have evolved a wide range of mechanisms to contend...

Besides fluorine, oxygen is the most electronegative element with the highest reduction potential in biological systems. Metabolic pathways in mammalian cells utilize oxygen as the ultimate oxidizing agent to harvest free energy. They are very efficient, but not without risk of generating various oxygen radicals. These cells have good antioxidative defense mechanisms to neutralize these radical...

Atlantic cod, Gadus morhua, were exposed to a progressive stepwise decline in water oxygen pressure ð19:9; 13:2; 10:5; 8:4; 6:2 and 4:3 kPa PO2Þ: Fish swimming speed and indicators of primary and secondary stress (e.g. blood cortisol and lactate) were measured to assess whether a severe shift in physiological homeostasis (i.e. stress) preceded any change in behaviour or vice versa. Swimming spe...

All cells produce reactive oxygen species (ROS) as by-products of their metabolism. In addition to being cytotoxic, ROS act as regulators of a wide range of developmental and physiological processes. Little is known about the molecular mechanisms underlying the perception of ROS and initiation of cellular responses in eukaryotes. Using the unicellular green alga Chlamydomonas reinhardtii, we de...

introduction: endoscopy is an invasive and painful procedure in children. since children can not tolerate pain and stress, sedation is necessary in pediatric endoscopy. the aim of this study was comparison of propofol versus intravenous midazolam for reducing anxiety in children.   materials and methods: in this study, 103 patients (2-14 years old) in whom endoscopy was indicated were divided i...

septicaemia caused by gram-negative pathogens is a dangerous infection which is associated with high incidence of liver dysfunction. the severe and acute hepatotoxicity is presumably due to massive release of endotoxin into systemic circulation after bacterial killing. the direct toxic effect of endotoxin is probably due to the increased production of reactive oxygen intermediates as o 2 - , pe...

amodiaquine is an antimalarial drug used in the prophylaxis and treatment of this disease. however, hepatotoxicity as a life‑threatening adverse effect is associated with its clinical use. we evaluated amodiaquine-induced toxicity in isolated rat hepatocytes as an in vitro model for studying drug‑induced hepatotoxicity. this study attempts to investigate the protective effects of taurine and n-...

Oxidative stress has been widely implicated as an important factor in the aging process. Because mitochondrial respiration is the principal source of reactive oxygen within cells, the mitochondrially localized superoxide dismutase (SOD) 2 is thought to play an important front-line defensive role against aging-related oxidative stress. Although genetic studies with mutants deficient in SOD1, the...

All cells produce reactive oxygen species (ROS) as by-products of their metabolism. In addition to being cytotoxic, ROS act as regulators of a wide range of developmental and physiological processes. Little is known about the molecular mechanisms underlying the perception of ROS and initiation of cellular responses in eukaryotes. Using the unicellular green algaChlamydomonas reinhardtii, we dev...

OBJECTIVES In response to endoplasmic reticulum (ER) stress, endothelial cells initiate corrective pathways such as the unfolded protein response. Recent studies suggest that reactive oxygen species produced on the ER may participate in homeostatic signaling through Ras in response to ER stress. We sought to identify mechanisms responsible for this focal signaling pathway. APPROACH AND RESULT...