Basic Surgery MCQ Answer 002

Answer: ABCD

DISCUSSION:

Oxidants are reactive oxygen metabolites that have both physiologic and pathophysiologic roles. As potent oxidizing agents, oxidants are involved in cytochrome P 450–mediated oxidations, for example. In pathophysiologic processes associated with inflammation, injury, and infection, oxidants may be generated by activated neutrophils and in ischemia-reperfusion injury. During ischemia, the enzyme xanthine oxidase accumulates. When oxygen availability increases during reperfusion, O2• is formed in a reaction catalyzed by xanthine oxidase. Further oxidant formation ensues, causing the production of H2O2 and the extremely reactive hydroxyl ion (OH•). Oxidants may cause direct cell damage by the mechanisms of lipid peroxidation and cell membrane disruption, inhibition of ATP synthesis, reduction of cellular nicotinamide adenine dinucleotide (NAD), and oxidative damage to DNA and amino acids. In addition, oxidants may have a chemotactic role, leading to leukocyte infiltration and activation, causing further tissue damage by the release of cytotoxic proteases.

Category: Surgery MCQs