Was ist oxidativer Stress?

Abstract

Oxidative stress is defined as an overflow of oxidative metabolites either in the human body or in a compartment of the body. Today this chemical definition has been slightly modified and encompasses an elevation of oxidative metabolites or a relative deficiency of anti-oxidants. Molecular oxygen is the basis of many highly reactive oxidative species which are able to directly damage or lead to the generation of secondary reactions which then initiate oxidative processes. The cell has established numerous mechanisms and strategies to antagonise those oxidative processes at different steps. Many diseases have been shown to be either related to or even be initiated by oxidative processes. The eye is at high risk to be damaged by oxidative mechanisms. One major reason is its permanent exposition to oxidative stimuli. The biochemical composition of ocular structures, especially that of the retina (unsaturated fatty acids), is an important factor making the eye more susceptible as compared to other organs. Ocular ischaemia, ischaemia or hypoxia of the retina, diabetic retinopathy and glaucoma are important disease entities that are initiated or propagated by oxidative processes. Ischaemic processes lead to classical reactions of the oxidative pathway. This is no longer believed to be the case in diabetic retinopathy. Here, advanced glycation end products (AGE's) and related species are able to induce oxidative reactions and the expression of growth factors. In age-related macular degeneration, photodynamic processes that already occur in childhood are believed to be a major factor contributing to the pathogenesis of the disease process. In addition, the expression of growth factors and new vessel growth can be initiated via inflammatory reactions or oxidative metabolites.

The state of the reticulated and vascular eye membranes of rabbit with diabetes mellitus, modeled by Dithi-zone. Information 2. Antioxidant enzymes and su¬peroxide oxygen

“…Ýòî, åñòåñòâåííî, ïðèâîäèò ê íàêîïëåíèþ â òêàíè ïåðåêèñè âîäîðîäà, íå îáåçâðåaeåííîé íè ïóòåì åå âîññòàíîâëåíèÿ ïåðîêñèäàçîé äî âîäû çà ñ÷åò îêèñëåíèÿ ãëóòàòèîíà, íè ðàñùåïëåíèåì íà âîäó è êèñëîðîä êàòàëàçîé è, êàê ñëåäñòâèå ýòîãî,ê îêèñëèòåëüíîìó ñòðåññó. Ïîñëåäíèé åùå áîëåå àêòèâèçèðóåòñÿ â ðåçóëüòàòå ïðèñîåäèíåíèÿ òðåòüåãî ýëåêòðîíà ìîëåêóëîé ïåðîêñèäà âîäîðîäà è îáðàçîâàíèÿ ïðè ýòîì âûñîêî ðåàêöèîííî-ñïîñîáíîãî ãèäðîêñèëüíîãî ðàäèêàëà, äðóãèõ ïðîèçâîäíûõ ñóïåðîêñèäà è ïîâðåaeäåíèÿ èìè ìàêðîìîëåêóë êëåòîê, èíèöèèðîâàíèÿ öåïíîé ðåàêöèè ïåðîêñèäíîãî îêèñëåíèÿ íåíàñûùåííûõ aeèðíûõ êèñëîò ëèïèäîâ ñ ïîâðåaeäåíèåì ñòðóêòóðû è ôóíêöèè ìåìáðàí [14,24,25] Êîíå÷íî, âîçìîaeíû è êàêèå-òî äðóãèå, äîïîëíèòåëüíûå ê ðàññìîòðåííîìó âûøå, ôàêòîðû òàêîãî íåãàòèâíîãî äëÿ ñåò÷àòêè âëèÿíèÿ õåëàòèðîâàíèÿ öèíêà. Íàïðèìåð, òàêèå êàê íàðóøåíèå òðàíñïîðòà ìîëåêóë öèíêà åãî ïåðåíîñ÷èêàìè, ýêñïðåññèðóþùèìèñÿ â êëåòêàõ ïèãìåíòíîãî ýïèòåëèÿ ñåò÷àòêè, ÷òî ñëåäóåò èç ïóáëèêàöèè Leung K. W. et al, 2008 [42].…”

“…Íî îñîáî îòìå-òèì, ÷òî äëÿ ñåò÷àòêè, ÿâëÿþùåéñÿ ìåòàáîëè÷åñêè íàèáîëåå àêòèâíîé ñòðóêòóðîé â îðãàíèçìå ÷åëîâåêà [23], ýòîò ñòðåññ îñîáåííî îïàñåí. Âåäü èìåííî äëÿ íåå õàðàêòåðíû âûñîêîå ñîäåðaeàíèå ïîëèíåíàñûùåííûõ aeèðíûõ êèñëîò [24], î÷åíü âûñîêèé óðîâåíü îêèñëåíèÿ ãëþêîçû è ïîòðåáëåíèÿ êèñëîðîäà [8,31,33,34].  ëèòåðàòóðå [56] îòìå÷àåòñÿ, ÷òî óñâîåíèå êèñëîðîäà òêàíüþ ñåò÷àòêè âîîáùå ÿâëÿåòñÿ íàèáîëåå âûðàaeåííûì ñðåäè âñåõ ñòðóêòóð îðãàíèçìà, âêëþ÷àÿ ìîçã.…”

Relationship of Uric Acid with Superoxide Dismutase (Sod) in Induced Hyperuricemic Rat Model

“…Superoxide dismutase is believed to serve as first line of defense against toxicity of superoxide radicals. Also takes part in cell signaling regarding to reactive oxygen species levels [4]. Superoxide is one of the main reactive oxygen species in the cell and as such, SOD serves a key antioxidant role.…”