Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học quốc tế cung cấp cho các bạn kiến thức về ngành y đề tài: Clinical review: Oxygen as a signaling molecule. | Bartz and Piantadosi Critical Care 2010 14 234 http content 14 5 234 CRITICAL CARE REVIEW L_ Clinical review Oxygen as a signaling molecule Raquel R Bartz - 2 and Claude A Piantadosi1-2-3 Abstract Molecular oxygen is obviously essential for conserving energy in a form useable for aerobic life however its utilization comes at a cost - the production of reactive oxygen species ROS . ROS can be highly damaging to a range of biological macromolecules- and in the past the overproduction of these short-lived molecules in a variety of disease states was thought to be exclusively toxic to cells and tissues such as the lung. Recent basic research- however has indicated that ROS production - in particular- the production of hydrogen peroxide - plays an important role in both intracellular and extracellular signal transduction that involves diverse functions from vascular health to host defense. The present review summarizes oxygen s capacityacting through its reactive intermediates- to recruit the enzymatic antioxidant defenses- to stimulate cell repair processes- and to mitigate cellular damage. Oxygen as a biological molecule Oxygen O2 is perhaps the single most important molecule for the maintenance of life on Earth. The geological record indicates that our planet s atmospheric O2 concentration has fluctuated substantially and this is thought to be involved in the evolution of a broad array of antioxidant defenses. This important and reactive molecule first appeared in our atmosphere over billion years ago and millions of years ago may have been as high as 35 of the atmospheric composition. Not until atmospheric O2 levels had stabilized at around 21 more than 500 million years ago and intracellular mechanisms evolved to utilize O2 efficiently and to contain its reactivity however did complex multicellular organisms began to proliferate. Because O2 has a high standard oxidation-reduction redox potential it is an ideal electron acceptor - and is .
