Oxidative stress agent

Isol. from Brevibacterium ammoniagenes. Oxidative stress metab. of various nocar-dioform bacteria inch Corynebacterium and Micrococcus spp. Oxidative stress agent. 

SECM can be used to probe transport activity of biological systems, such as single cells, ion transport across channels, and enzyme activity. Experimentally, cells, enzymes, or ion channels are immobilized and a small size electrode (micron to nanometer size) is positioned a few microns above. By stimulating these samples with an oxidative stress agent (by the action of the substrate and cofactors, or by the presence of ions), biological... 

Although it is widely accepted that ischaemia/ reperfusion-induced oxidant stress is associated with a reduction of Na/K ATPase activity, it is difficult to determine which features of this process are responsible for this effect. A classical approach to this type of problem has been to determine the effect of the application of selected metabolites or agents on the activity of the enzyme of interest, an approach that has been exploited for the sarcolemmal Na/K ATPase and glutathione (Haddock et al., 1990). The application of GSH (O.l-l.OmM) induces a concentration-dependent increase in the activity of a bovine isolated ventricular Na/K ATPase preparation (determined by the ouabain-sensitive hydrolysis of ATP to release inorganic phosphate). In the presence of 1 mM GSH there was a 38% stimulation of activity compared to untreated control... 

These two mechanisms (DNA damage by OH or by activation of nucleases) are not mutually exclusive, i.e. they could both take place (Fig. 13.1). Indeed, there is evidence consistent with the existence of both mechanisms. Their relative importance may depend on the cell type used and on how the oxidative stress is imposed (Halliwell and Aruoma, 1991). For example, chelating agents that bind iron ions into chelates unable to generate OH (such as desferrioxamine. 

The development of nontransmittable chronic illnesses is associated with the presence of oxidative agents in the body. These agents are found in air, water, or food or can be produced in the body s cells. Their high content in body cells causes an imbalance that results in oxidative stress damaging proteins, DNA, and others. As a result of this deterioration, an increase in the risk of nontransmittable chronic illnesses has been noted. In order to prevent or decrease oxidative stress, the consumption of foods rich in antioxidants, such as fruits and vegetables, is recommended (van Dokkum and others 2008 Liu 2003). 

It has been suggested that tamoxifen, one of the most effective therapeutic and chemopreventive agent for breast cancer, modulates protein kinase C through oxidative stress in breast cancer cells [194], Unfortunately, most breast cancers initially responsive to tamoxifen treatment later become resistant. Schiff et al. [195] suggested that the conversion of breast tumors to a tamoxifen-resistant phenotype is associated with oxidative stress and depends on significantly enhanced SOD activity in tumors. 

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