China 
Africa 
Explore chapters and articles related to this topic
The No-Reflow Phenomenon: A Misnomer?
Published in Samuel Sideman, Rafael Beyar, Analysis and Simulation of the Cardiac System — Ischemia, 2020
Lewis C. Becker, Giuseppe Ambrosio, John Manissi, Harlan F. Weisman
Those are complicated questions. First of all, with respect to SOD being used alone, one answer to the question of why you might not need catalase is that there is enough catalase activity or related enzyme activity, such as glutathione peroxidase in the myocardium, even during ischemia. Another answer is that in order to produce the hydroxyl radicals by way of the Fenton reaction you have to have superoxide. If you detoxify the superoxide fast enough by exogenous SOD, you won’t make much hydroxyl radical. That is not saying, however, that SOD is the only way to prevent free radical injury. Sopping up hydroxyl radicals by specific scavengers may turn out to be even more effective. Also, the binding of free iron with chelators such as desferroxamine might be an effective way of preventing hydroxyl radical formation. With respect to the human heart not having xanthine oxidase, that is, of course, not a problem with the dog study, but there are other known sources of free radicals besides xanthine oxidase. Drs. Lucchesi and Mullane have emphasized neutrophils as an important source of free radical formation. Also, cellular energy-producing processes normally lead to free radical production, and metabolism of catecholamines and prostaglandins may also lead to formation of free radicals.
Histoplasmosis
Published in Rebecca A. Cox, Immunology of the Fungal Diseases, 2020
A number of antimicrobial systems operative within PMNL have been described.43,61,62 It is convenient to divide such mechanisms into two types: oxidative and nonoxidative.62 The oxidative systems derive from the presence in PMNL of an activatable, membrane-associated enzyme system, NAD(P)H oxidase.62 Phagocytosis of particles or certain other membrane disturbances activate this oxidase which catalyzes the following reaction: . The superoxide anions ) are unstable and undergo dismutation to hydrogen peroxide and oxygen: . Dismutation occurs spontaneously, an event favored by low pH, or is enzymatically catalyzed by superoxide dismutase.62 Hydrogen peroxide and superoxide anions undergo additional reactions, especially when transition metals are present. For example, hydroxyl radicals (OH.) are generated in the Fenton reaction: H2O2 + Fe2+ → OH. + OH− + Fe3+. Iron bound to lactoferrin can support hydroxyl radical generation.
The Use of Brain Slices in the Study of Free Radical Actions
Published in Avital Schurr, Benjamin M. Rigor, BRAIN SLICES in BASIC and CLINICAL RESEARCH, 2020
During cellular respiration, oxygen is reduced to water by the acceptance of four electrons. Because of spin restriction on the electrons, however, oxygen usually accepts a single electron at a time. Addition of a single electron to oxygen produces the superoxide radical anion, . Fridovich11 has proposed that superoxide is a major factor in the toxicity of oxygen. Addition of a second electron results in the formation of hydrogen peroxide, H2O2. The dismutation of superoxide to hydrogen peroxide can occur spontaneously or can be catalyzed by the enzyme superoxide dismutase. Since peroxide has no unpaired electrons, it is not technically a free radical. It is a stable compound that can diffuse for long distances in a cellular system. However, when peroxide encounters transition metals such as ferrous or cuprous ions, it readily accepts an electron to produce the hydroxyl free radical, OH. The reaction of peroxide with iron to produce hydroxyl radicals is known as the Fenton reaction. The hydroxyl radical is an extremely reactive compound that quickly oxidizes almost any organic molecule it encounters and is considered to be the most damaging of the reactive oxygen intermediates.
Psidium cattleianum fruit extract prevents systemic alterations in an animal model of type 2 diabetes mellitus: comparison with metformin effects
Published in Biomarkers, 2023
Juliane De Souza Cardoso, Fernanda Cardoso Teixeira, Julia Eisenhardt De Mello, Mayara Sandrielly Soares De Aguiar, Pathise Souto Oliveira, Juliane Torchelsen Saraiva, Marcia Vizzotto, Fabiane Borelli Grecco, Claiton Leoneti Lencina, Roselia Maria Spanevello, Rejane Giacomelli Tavares, Francieli Moro Stefanello
Ferroptosis has recently been identified as a possible cause of pancreatic β-cell death. It is characterised by a decrease in mitochondrial volume, reduction or disappearance of mitochondrial cristae, and rupture of the outer membrane, and is usually associated with oxidative stress and increased iron deposition in the serum and islets (Li et al.2020). Iron is a potentially toxic molecule because it can accept and donate electrons. Therefore, the Fenton reaction involves the oxidation of an iron molecule using H2O2 to form a hydroxyl radical (OH.), one of the most potent free radicals capable of reacting with various cellular constituents (Imam et al.2017). Extracts obtained from fruits rich in phenolic compounds, such as orange, bergamot, grape, and chokeberry, or even isolated compounds, such as anthocyanins, curcumin, quercetin, and resveratrol, are effective in protecting different cells from ferroptosis (Imam et al.2017). Among the mechanisms involved, we highlight iron chelation, decreased iron absorption, prevention of oxidative stress, reduction in ROS levels and lipoperoxidation, increase in the activity and expression of antioxidant enzymes, and reduction of inflammation (Imam et al.2017).
Impact of nonionizing electromagnetic radiation on male infertility: an assessment of the mechanism and consequences
Published in International Journal of Radiation Biology, 2022
Rohit Gautam, Eepsita Priyadarshini, JayPrakash Nirala, Paulraj Rajamani
Fenton reaction can be summarized in three different steps and explained in form of chemical equations as follows:The interaction of Fe 2+ salt with hydrogen peroxide results in the generation of free hydroxyl ions (•OH). Any trace iron (Fe3+) present further reacts with hydrogen peroxide leading to the formation of hydrogen ion and superoxides, given by the following formula Thereafter, hydrogen peroxide interacts with the superoxide ion leading to the formation of •OH
Targetting ferroptosis for blood cell-related diseases
Published in Journal of Drug Targeting, 2022
Zhe Chen, Jinyong Jiang, Nian Fu, Linxi Chen
Ferroptosis is caused by increased cellular iron level. In detail, accumulated cellular iron level and lipoxygenase (LOX) enzymes catalyse the lipid peroxidation of unsaturated fatty acids which are highly expressed on the cell membrane via Fenton reactions, thereby inducing the occurrence of ferroptosis. Fenton reaction is a chemical reaction in which many known organic compounds, such as carboxylic acids, alcohols, esters, etc. are oxidised into inorganic states after the mixed solution of hydrogen peroxide (H2O2) and ferrous ions, thus producing a large number of OH· free radicals with strong oxidation capacity [5]. In addition to increased cellular iron level, ferroptosis is induced by glutathione (GSH) depletion and antioxidant enzyme glutathione peroxidase 4 (Gpx4) deficiency.