The Experts below are selected from a list of 14589 Experts worldwide ranked by ideXlab platform
Hideo Utsumi - One of the best experts on this subject based on the ideXlab platform.
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Are Free Radical Reactions increased in the diabetic eye
Antioxidants & redox signaling, 2007Co-Authors: Mayumi Yamato, Ken-ichi Yamada, Shingo Matsumoto, Katsuaki Ura, Tatsuya Naganuma, Toyoshi Inoguchi, Toshiaki Watanabe, Hideo UtsumiAbstract:Reactive oxygen species (ROS) are thought to play a significant role in the development of diabetic retinopathy; however, no direct evidence supports ROS generation in vivo. This study used in vivo electron spin resonance (ESR) spectroscopy with a surface resonator to detect local Free Radical Reactions. The ESR signal decay of carbamoyl-PROXYL was enhanced in the eyes of streptozotocin (STZ)-induced diabetic mice. This enhanced signal decay was suppressed by the administration of SOD or the pretreatment with aminoguanidine. We demonstrate, for the first time, specific Free Radical Reactions in the eyes of mice with STZ-induced diabetes.
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Enhanced intraarticular Free Radical Reactions in adjuvant arthritis rats.
Free radical research, 2006Co-Authors: Ken-ichi Yamada, Toshitaka Nakamura, Hideo UtsumiAbstract:One of the reasons of rheumatoid arthritis (RA) development is widely recognized the relation of Free Radical Reactions in tissue injuries. The aim of this study was to evaluate the location where in vivo Free Radical Reactions was enhanced in adjuvant arthritis (AA) model rats using in vivo electron spin resonance (ESR)/nitroxyl spin probe technique. The signal decay after intravenous injection of spin probe was enhanced in AA than that in control and suppressed by the pre-treatment of dexamethasone (DXT). Interestingly, the decay in joint cavity occurred prior to paw swelling of AA and suppressed by a simultaneous injection of Free Radical scavengers, indicating that the enhancement of Free Radical Reactions in joint cavity of AA rats. This technique would be useful tool to determine the location of the enhanced Free Radical Reactions and evaluate the activity of antioxidant medicine with non-invasive real-time measurement.
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In vivo ESR measurements of Free Radical Reactions in living mice
Toxicology letters, 1995Co-Authors: Hideo Utsumi, Kazuhiro Ichikawa, K. TakeshitaAbstract:In vivo ESR measurements were carried out to estimate Free Radical Reactions in living mice using nitroxyl Radicals as probes. The ESR signal of nitroxyl Radical which was intravenously or intramuscularly injected to living female ddY mice decreased gradually by reducing to the corresponding hydroxylamine. The reduction rate was enhanced by oxidative stress, and pre-treatment of antioxidants suppressed the enhancement of signal decay. Oral administration of carbon tetrachloride enhanced signal decay in upper abdomen but not in thorax. These results indicated that Free Radicals, which can reduce nitroxyl Radical, were produced in the upper abdomen by oral administration of carbon tetrachloride.
K. Takeshita - One of the best experts on this subject based on the ideXlab platform.
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In vivo ESR measurement of Free Radical Reactions in living animals using nitroxyl probes
Bioradicals Detected by ESR Spectroscopy, 1995Co-Authors: H. Utsumi, K. TakeshitaAbstract:This chapter covers the in vivo ESR measurement methods to estimate Free Radical Reactions in living mice using nitroxyl Radicals as probes. One of the following nitroxyl Radicals, 2,2,6,6-tetramethylpiperidine-1 -oxyl (TEMPO), 2,2,5,5-tetramethylpyrrolidine-1-oxyl (PROXYL), 4,4-dimethyloxazolidine-3-oxyl (DOXYL), and their derivatives, was dissolved in isotonic buffer and was intravenously, intramuscularly, transtracheally or intra-peritoneally injected into female ddY mice. The ESR signal of nitroxyl Radical in living mice decreased gradually by reducing to the corresponding hydroxylamine. The reduction rate depended on physiological and pathological conditions such as aging, γ-irradiation, and oxidative stress. Pre-treatment of antioxidants reduced Che enhancement of signal decay by oxidative stress. Alveolar cell membrane had reducing system for nitroxyl Radicals, and the activity was regulated by lipophilic SH modifying reagents. These results clearly demonstrate that in vivo ESR measurement with nitroxyl Radical as a probe is very useful technique to estimate in vivo Free Radical Reactions and to evaluate their relation to physiological and pathological phenomena.
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In vivo ESR measurements of Free Radical Reactions in living mice
Toxicology letters, 1995Co-Authors: Hideo Utsumi, Kazuhiro Ichikawa, K. TakeshitaAbstract:In vivo ESR measurements were carried out to estimate Free Radical Reactions in living mice using nitroxyl Radicals as probes. The ESR signal of nitroxyl Radical which was intravenously or intramuscularly injected to living female ddY mice decreased gradually by reducing to the corresponding hydroxylamine. The reduction rate was enhanced by oxidative stress, and pre-treatment of antioxidants suppressed the enhancement of signal decay. Oral administration of carbon tetrachloride enhanced signal decay in upper abdomen but not in thorax. These results indicated that Free Radicals, which can reduce nitroxyl Radical, were produced in the upper abdomen by oral administration of carbon tetrachloride.
K. U. Ingold - One of the best experts on this subject based on the ideXlab platform.
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Kinetic and mechanistic studies of Free Radical Reactions in the 21st century
Pure and Applied Chemistry, 1997Co-Authors: K. U. IngoldAbstract:The past 50 years has seen an incredible growth in our understanding of Free Radical Reactions in homogeneous gaseous and liquid systems. Fifty years ago, so far as the vast majority of chemists were concerned, Radicals were overly reactive species of no practical value or interest since all Radical-mediated Reactions were presumed to give gunk and tars. This negative view of Radical Reactions persisted even long after the successful commercialization of the Free Radical polymerization of vinyl monomers. Half a century ago the prevailing view of an organic or physical organic chemist about any of their colleagues who expressed an interest in research into Free Radical Reactions can best be summarized by a joking remark once made by the father of physical organic chemistry:
Laszlo Wojnarovits - One of the best experts on this subject based on the ideXlab platform.
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Mechanistic study on thiacloprid transformation: Free Radical Reactions
Journal of Photochemistry and Photobiology A-chemistry, 2017Co-Authors: Georgina Rózsa, Krisztina Schrantz, László Szabó, Erzsebet Takacs, Laszlo WojnarovitsAbstract:Abstract Free Radical induced oxidation/reduction mechanisms of the hazardous water contaminant thiacloprid have been unravelled using pulse radiolysis techniques involving transient spectral analysis and redox titration experiments. The OH-induced oxidation of thiacloprid proceeds with appreciable rate, the reaction rate constant has been determined to be k OH = 4.8 × 10 9 mol −1 L s −1 . The OH attack leaves behind a rather complex Free Radical system consisting of ∼9% α-aminoalkyl Radicals, ∼31% aminyl + aminium nitrogen centred Radicals, ∼46% Radicals at the sulfur and ∼14% hydroxycyclohexadienyl Radical of the pyridyl moiety. Since ∼86% of Radicals are formed on the key cyanoiminothiazolidine pharmacophore, OH is anticipated to be an appropriate candidate for inactivation of this biologically active pollutant. The one-electron reduction exerted by e aq − occurs at a diffusion controlled rate. As a result of the e aq − attack pyridinyl Radical forms that takes part in subsequent protonation and dechlorination processes. The course of events is anticipated to lead to the destruction of another important part of the molecule in respect to insecticidal activity.
Che‐ping Chuang - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of highly substituted pyrroles via oxidative Free Radical Reactions of β-aminocinnamates
Tetrahedron, 2006Co-Authors: An I Tsai, Che‐ping ChuangAbstract:Abstract Oxidative Free Radical Reactions of β-aminocinnamates are described. Imine Radicals produced by tetra- n -butylammonium cerium(IV) nitrate (TBACN) oxidation of enamines undergo efficient addition to the C–C double bond of β-aminocinnamates. This TBACN mediated Free Radical reaction between β-aminocinnamates and enamines provides a novel method for the synthesis of highly substituted pyrroles. The direct TBACN oxidation of β-aminocinnamates gave the dimerization products effectively.
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Oxidative Free Radical Reactions of enamino esters
Tetrahedron, 2004Co-Authors: Che‐ping ChuangAbstract:Abstract Oxidative Free Radical Reactions of enamino esters are described. Electrophilic carbon-centered Radicals produced by the cerium(IV) ammonium nitrate (CAN) oxidation of β-dicarbonyl compounds undergo efficient addition to the C–C double bond of enamino esters. This CAN mediated Free Radical reaction between enamino esters and β-dicarbonyl compounds provides a novel method for the synthesis of highly substituted pyrroles. The direct CAN oxidation of β-enaminocinnamates gave the dimerization products effectively.
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Solvent effects on the oxidative Free Radical Reactions of 2-amino-1,4-naphthoquinones
Tetrahedron, 2004Co-Authors: Chao Ming Tseng, Che‐ping ChuangAbstract:Abstract Solvent effects on the manganese (III) initiated oxidative Free Radical Reactions of 2-amino-1,4-naphthoquinones are described. This Free Radical reaction provides a novel method for the synthesis of benzo[f]indole-4,9-diones, benzo[f]indole-2,4,9-triones, benzo[b]carbazole-6,11-diones and benzo[b]acridine-6,11-diones. High chemoselectivity was observed in different solvents.
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Cerium salts in the oxidative Free Radical Reactions between 2-amino-1,4-naphthoquinones and β-dicarbonyl compounds
Tetrahedron, 2002Co-Authors: Chih Chung Tseng, Che‐ping ChuangAbstract:The oxidative Free Radical Reactions between 2-amino-1,4-naphthoquinones and β-dicarbonyl compounds mediated by cerium(IV) salts are described. In contrast to those mediated by manganese(III) acetate, the cerium(IV) mediated Free Radical reaction provides a novel method for the synthesis of benzo[f]indole-4,9-diones exclusively. This high selectivity is due to the strong oxaphilicity of the cerium salts.
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Oxidative Free Radical Reactions between 2-benzyl-1,4-naphthoquinones and β-dicarbonyl compounds
Tetrahedron, 2001Co-Authors: An I Tsai, Che‐ping ChuangAbstract:Abstract Oxidative Free Radical Reactions between 2-benzyl-1,4-naphthoquinones and β-dicarbonyl compounds are described. Electrophilic carbon-centered Radicals produced by the manganese(III) acetate or cerium(IV) ammonium nitrate oxidation of β-dicarbonyl compounds undergo efficient addition to a C–C double bond of quinone ring. This Free Radical reaction provides a novel method for the synthesis of naphthacene-5,12-diones.
