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Oxidative stress mechanisms in tissue injury. Free radical toxicity induced by xenobiotics and the subsequent detoxification by cellular enzymes (termination).. Oxidative stress reflects an imbalance between the systemic manifestation of reactive oxygen species and a biological system's ability to readily detoxify the reactive intermediates or to repair the resulting damage. [1]
Oxidative stress is the most controllable risk factor and is the best understood. The online Merriam-Webster Medical Dictionary defines oxidative stress as, "physiological stress on the body that is caused by the cumulative damage done by free radicals inadequately neutralized by antioxidants and that is held to be associated with aging."
As a result, the increased concentration of Ca 2+ directly increases the stress on mitochondria, resulting in excessive oxidative phosphorylation and production of reactive oxygen species (ROS) via the activation of nitric oxide synthase, ultimately leading to cell death. Aβ was also found aiding this route to neurotoxicity by enhancing neuron ...
Oxidative free radicals, such as the hydroxyl radical and the superoxide radical, can cause DNA damages, and such damages have been proposed to play a key role in the aging of crucial tissues. [20] DNA damage can result in reduced gene expression , cell death and ultimately tissue dysfunction.
XthA (exonuclease III, a DNA repair enzyme) and KatE (catalase) are known to play important roles in the defense against oxidative stress but KatF regulon genes are not induced by oxidative stress. [2] There is an overlap between oxidative stress response and other regulatory networks like heat shock response, SOS response.
In cultured human neurons, these gene promoters are selectively damaged by oxidative stress. Thus Lu et al. [36] concluded that DNA damage may reduce the expression of selectively vulnerable genes involved in learning, memory and neuronal survival, initiating a program of brain aging that starts early in adult life. [citation needed]
The main reason for the acute phase of ischemia-reperfusion injury is oxygen deprivation and, therefore, arrest of generation of ATP (cellular energy currency) by mitochondria oxidative phosphorylation. Tissue damage due to the general energy deficit during ischemia is followed by reperfusion (increase of oxygen level) when the injury is enhanced.
Biological psychiatry or biopsychiatry is an approach to psychiatry that aims to understand mental disorder in terms of the biological function of the nervous system.It is interdisciplinary in its approach and draws on sciences such as neuroscience, psychopharmacology, biochemistry, genetics, epigenetics and physiology to investigate the biological bases of behavior and psychopathology.