Topic
Oxidative stress
About: Oxidative stress is a research topic. Over the lifetime, 86513 publications have been published within this topic receiving 3845790 citations. The topic is also known as: oxydative stress.
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TL;DR: Transgenic mice that overexpress human catalase localized to the peroxisome, the nucleus, or mitochondria were generated and the importance of mitochondria as a source of radicals was reinforced.
Abstract: To determine the role of reactive oxygen species in mammalian longevity, we generated transgenic mice that overexpress human catalase localized to the peroxisome, the nucleus, or mitochondria (MCAT). Median and maximum life spans were maximally increased (averages of 5 months and 5.5 months, respectively) in MCAT animals. Cardiac pathology and cataract development were delayed, oxidative damage was reduced, H2O2 production and H2O2-induced aconitase inactivation were attenuated, and the development of mitochondrial deletions was reduced. These results support the free radical theory of aging and reinforce the importance of mitochondria as a source of these radicals.
1,629 citations
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01 Jun 2001TL;DR: The alternative oxidase and possibly NDin(NADH) function to limit mitochondrial ROS production by keeping the ETC relatively oxidized, together with small antioxidants such as glutathione, that help remove ROS.
Abstract: The production of reactive oxygen species (ROS), such as O2- and H2O2, is an unavoidable consequence of aerobic metabolism. In plant cells the mitochondrial electron transport chain (ETC) is a major site of ROS production. In addition to complexes I-IV, the plant mitochondrial ETC contains a non-proton-pumping alternative oxidase as well as two rotenone-insensitive, non-proton-pumping NAD(P)H dehydrogenases on each side of the inner membrane: NDex on the outer surface and NDin on the inner surface. Because of their dependence on Ca2+, the two NDex may be active only when the plant cell is stressed. Complex I is the main enzyme oxidizing NADH under normal conditions and is also a major site of ROS production, together with complex III. The alternative oxidase and possibly NDin(NADH) function to limit mitochondrial ROS production by keeping the ETC relatively oxidized. Several enzymes are found in the matrix that, together with small antioxidants such as glutathione, help remove ROS. The antioxidants are kept in a reduced state by matrix NADPH produced by NADP-isocitrate dehydrogenase and non-proton-pumping transhydrogenase activities. When these defenses are overwhelmed, as occurs during both biotic and abiotic stress, the mitochondria are damaged by oxidative stress.
1,583 citations
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TL;DR: Recent results confirm the prominent role of astrocytes in glutathione metabolism and the defense against reactive oxygen species in brain and suggest an involvement of a compromised astroglial glutATHione system in the oxidative stress reported for neurological disorders.
1,582 citations
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TL;DR: Assessment of oxidativedamage to biomolecules by means of emerging technologies based on products of oxidative damage to DNA, lipids, and proteins would not only advance the understanding of the underlying mechanisms but also facilitate supplementation and intervention studies designed and conducted to test antioxidant efficacy in human health and disease.
Abstract: Free radicals and other reactive oxygen species (ROS) are constantly formed in the human body. Free-radical mechanisms have been implicated in the pathology of several human diseases, including cancer, atherosclerosis, malaria, and rheumatoid arthritis and neurodegenerative diseases. For example, the superoxide radical (O2·−) and hydrogen peroxide (H2O2) are known to be generated in the brain and nervous system in vivo, and several areas of the human brain are rich in iron, which appears to be easily mobilizable in a form that can stimulate free-radical reactions. Antioxidant defenses to remove O2·− and H2O2 exist. Superoxide dismutases (SOD) remove O2·− by greatly accelerating its conversion to H2O2. Catalases in peroxisomes convert H2O2 into water and O2 and help to dispose of H2O2 generated by the action of the oxidase enzymes that are located in these organelles. Other important H2O2-removing enzymes in human cells are the glutathione peroxidases. When produced in excess, ROS can cause tissue injury. However, tissue injury can itself cause ROS generation (e.g., by causing activation of phagocytes or releasing transition metal ions from damaged cells), which may (or may not, depending on the situation) contribute to a worsening of the injury. Assessment of oxidative damage to biomolecules by means of emerging technologies based on products of oxidative damage to DNA (e.g., 8-hydroxydeoxyguanosine), lipids (e.g., isoprostanes), and proteins (altered amino acids) would not only advance our understanding of the underlying mechanisms but also facilitate supplementation and intervention studies designed and conducted to test antioxidant efficacy in human health and disease.
1,557 citations
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TL;DR: Observation of the role of different oxygen‐derived species in DNA cleavage reactions has been used to determine the extent of oxidative damage to DNA in vivo and to investigate the mechanism of DNA damage by ionizing radiation and chemical carcinogens.
1,555 citations