A study of free radical chemistry: their role and pathophysiological significance.

Abstract

Oxygen is one of the most important molecules on Earth mainly because of the biochemical symmetry of oxygenic photosynthesis and aerobic respiration that can maintain homeostasis within our planet's biosphere. Oxygen can also produce toxic molecules, reactive oxygen species (ROS). ROS play a dual role in biological systems, since they can be either harmful or beneficial to living systems. They can be considered a double-edged sword because at moderate concentrations, nitric oxide (NO•), superoxide anion, and related reactive oxygen species play an important role as regulatory mediators in signalling processes. Many of the ROS-mediated responses actually protect the cells against oxidative stress and re-establish "redox homeostasis". On the other hand, overproduction of ROS has the potential to cause damage. In the recent decades, ROS has become a focus of interest in most biomedical disciplines and many types of clinical research. Increasing evidence from research on several diseases shows that oxidative stress is associated with the pathogenesis of diabetes mellitus, obesity, cancer, cardiovascular diseases, inflammation, ischaemia/reperfusion injury, obstructive sleep apnea, neurodegenerative disorders, hypertension and ageing.

The inverted CD4:CD8 ratio is associated with gender-related changes in oxidative stress during aging

“…We hypothesized here that the OS can be particularly associated with immunosenescence phenotype, including the inverted CD4:CD8 ratio and increased CMV serology. This hypothesis is supported by previous studies that have associated OS with the inflammatory status [24][25][26][27] as well as with CMV reactivation [28]. Furthermore, the OS can regulate viral replication and increased levels of oxidant markers were associated with latent CMV infection [29,30].…”

Oxidative Stress during HIV Infection: Mechanisms and Consequences

“…They include hydroxyl radical (HO • ), singlet oxygen ( 1 O 2 ), superoxide anion (O 2 •− ), hydrogen peroxide (H 2 O 2 ), and other reactive species [1, 2]. ROS are produced in various cellular processes and organelles: electron leakage from the mitochondrial electron transport chain (ETC), degradation of lipids, amino acids, and biogenic polyamines, protein folding in the lumen of endoplasmic reticulum (ER), and so forth [3–7].…”

“…The most reactive ROS is the hydroxyl radical, HO • , the one-electron oxidized form of the hydroxide ion (HO − ) [1, 13]. It can oxidize almost any molecule in its proximity including DNA, phospholipids, and proteins [13, 14].…”

Functional interplay between ATM/ATR-mediated DNA damage response and DNA repair pathways in oxidative stress

“…However, ROS generation periodically exceeds antioxidant defense capacity, leading to oxidative stress in cells. Oxidative stress is implicated in the pathogeneses of cancer, aging, neurodegenerative disorders, diabetes mellitus, obesity, heart failure, cardiovascular diseases, inflammation, ischemia/reper-fusion injury, kidney injury/failure, obstructive sleep apnea, and hypertension [14, 15]. Research into oxidative stress is attracting attention of most biomedical disciplines, including both basic and translational research, as evidenced by approximately 121,000 search results in PubMed ® using “oxidative stress” as key words.…”