The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform
Dean P Jones - One of the best experts on this subject based on the ideXlab platform.
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Redox Systems biology of nutrition and oxidative stress
Journal of Nutrition, 2019Co-Authors: Kristine K Dennis, Dean P JonesAbstract:Diet and nutrition contribute to both beneficial and harmful aspects of oxidative processes. The harmful processes, termed oxidative stress, occur with many human diseases. Major advances in understanding oxidative stress and nutrition have occurred with broad characterization of dietary oxidants and antioxidants, and with mechanistic studies showing antioxidant efficacy. However, randomized controlled trials in humans with free-radical-scavenging antioxidants and the glutathione precursor N-acetylcysteine have provided limited or inconsistent evidence for health benefits. This, combined with emerging Redox theory, indicates that holistic models are needed to understand the interplay of nutrition and oxidative stress. The purpose of this article is to highlight how recent advances in Redox theory and the development of new omics tools and data-driven approaches provide a framework for future nutrition and oxidative stress research. Here we describe why a holistic approach is needed to understand the impact of nutrition on oxidative stress and how recent advances in omics and data analysis methods are viable tools for Systems nutrition approaches. Based on the extensive research on glutathione and related thiol antioxidant Systems, we summarize the advancing framework for diet and oxidative stress in which antioxidant Systems are a component of a larger Redox network that serves as a responsive interface between the environment and an individual. The feasibility for Redox network analysis has been established by experimental models in which dietary factors are systematically varied and oxidative stress markers are linked through integrated omics (metabolome, transcriptome, proteome). With this framework, integrated Redox network models will support optimization of diet to protect against oxidative stress and disease.
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selective targeting of the cysteine proteome by thioRedoxin and glutathione Redox Systems
Molecular & Cellular Proteomics, 2013Co-Authors: James R Roede, Douglas I Walker, Duc M Duong, Nicholas T Seyfried, Michael Orr, Yongliang Liang, Kurt D Pennell, Dean P JonesAbstract:ThioRedoxin (Trx) and GSH are the major thiol antioxidants protecting cells from oxidative stress-induced cytotoxicity. Redox states of Trx and GSH have been used as indicators of oxidative stress. Accumulating studies suggest that Trx and GSH Redox Systems regulate cell signaling and metabolic pathways differently and independently during diverse stressful conditions. In the current study, we used a mass spectrometry-based Redox proteomics approach to test responses of the cysteine (Cys) proteome to selective disruption of the Trx- and GSH-dependent Systems. Auranofin (ARF) was used to inhibit Trx reductase without detectable oxidation of the GSH/GSSG couple, and buthionine sulfoximine (BSO) was used to deplete GSH without detectable oxidation of Trx1. Results for 606 Cys-containing peptides (peptidyl Cys) showed that 36% were oxidized more than 1.3-fold by ARF, whereas BSO-induced oxidation of peptidyl Cys was only 10%. Mean fold oxidation of these peptides was also higher by ARF than BSO treatment. Analysis of potential functional pathways showed that ARF oxidized peptides associated with glycolysis, cytoskeleton remodeling, translation and cell adhesion. Of 60 peptidyl Cys oxidized due to depletion of GSH, 41 were also oxidized by ARF and included proteins of translation and cell adhesion but not glycolysis or cytoskeletal remodeling. Studies to test functional correlates showed that pyruvate kinase activity and lactate levels were decreased with ARF but not BSO, confirming the effects on glycolysis-associated proteins are sensitive to oxidation by ARF. These data show that the Trx system regulates a broader range of proteins than the GSH system, support distinct function of Trx and GSH in cellular Redox control, and show for the first time in mammalian cells selective targeting peptidyl Cys and biological pathways due to deficient function of the Trx system.
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nonequilibrium thermodynamics of thiol disulfide Redox Systems a perspective on Redox Systems biology
Free Radical Biology and Medicine, 2008Co-Authors: Melissa L Kemp, Dean P JonesAbstract:Understanding the dynamics of Redox elements in biologic Systems remains a major challenge for Redox signaling and oxidative stress research. Central Redox elements include evolutionarily conserved subsets of cysteines and methionines of proteins which function as sulfur switches and labile reactive oxygen species (ROS) and reactive nitrogen species (RNS) which function in Redox signaling. The sulfur switches depend on Redox environments in which rates of oxidation are balanced with rates of reduction through the thioRedoxins, glutathione/glutathione disulfide, and cysteine/cystine Redox couples. These central couples, which we term Redox control nodes, are maintained at stable but nonequilibrium steady states, are largely independently regulated in different subcellular compartments, and are quasi-independent from each other within compartments. Disruption of the Redox control nodes can differentially affect sulfur switches, thereby creating a diversity of oxidative stress responses. Systems biology provides approaches to address the complexity of these responses. In the present review, we summarize thiol/disulfide pathway, Redox potential, and rate information as a basis for kinetic modeling of sulfur switches. The summary identifies gaps in knowledge especially related to Redox communication between compartments, definition of Redox pathways, and discrimination between types of sulfur switches. A formulation for kinetic modeling of GSH/GSSG Redox control indicates that Systems biology could encourage novel therapeutic approaches to protect against oxidative stress by identifying specific Redox-sensitive sites which could be targeted for intervention.
Lars Kloo - One of the best experts on this subject based on the ideXlab platform.
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Electrolytes Based on TEMPO–Co Tandem Redox Systems Outperform Single Redox Systems in Dye‐sensitized Solar Cells
ChemSusChem, 2014Co-Authors: Jiayan Cong, Yan Hao, Gerrit Boschloo, Lars KlooAbstract:A new TEMPO-Co tandem Redox system with TEMPO and Co(bpy)(3)(2+/3+) has been investigated for the use in dye-sensitized solar cells (DSSCs). A large open-circuit voltage (V-OC) increase, from 862 mV to 965 mV, was observed in the tandem Redox system, while the short-circuit current density (J(SC)) was maintained. The conversion efficiency was observed to increase from 7.1% for cells containing the single Co(bpy)(3)(2+/3+) Redox couple, to 8.4% for cells containing the TEMPO-Co tandem Redox system. The reason for the increase in V-OC and overall efficiency is ascribed to the involvement of partial regeneration of the sensitizing dye molecules by TEMPO. This assumption can be verified through the observed much faster regeneration dynamics exhibited in the presence of the tandem system. Using the tandem Redox system, the faster recombination problem of the single TEMPO Redox couple is resolved and the mass-transport of the metal-complex-based electrolyte is also improved. This TEMPO-Co tandem system is so far the most effienct tandem Redox electrolyte reported not involving iodine. The current results show a promising future for tandem system as replacements for single Redox Systems in electrolytes for DSSCs.
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Strategies to improve the performance of one- electron Redox Systems in electrolytes for dyes-sensitized solar cells
2014Co-Authors: Lars Kloo, Jiajia Gao, Muthuraaman Bhagavathiachari, Jiayan CongAbstract:Strategies to improve the performance of one- electron Redox Systems in electrolytes for dyes-sensitized solar cells
Max M. Hansmann - One of the best experts on this subject based on the ideXlab platform.
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Organic Redox Systems Based on Pyridinium-Carbene Hybrids.
Journal of the American Chemical Society, 2019Co-Authors: Patrick W. Antoni, Tim Bruckhoff, Max M. HansmannAbstract:New Redox Systems with three oxidation states are highly sought-after, for example, for Redox-flow battery applications, selective reducing agents, or organic electronics. Herein, we describe a str...
Frank Marken - One of the best experts on this subject based on the ideXlab platform.
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Biphasic Voltammetry and Spectroelectrochemistry in Polymer of Intrinsic Microporosity—4-(3-Phenylpropyl)-Pyridine Organogel/Aqueous Electrolyte Systems: Reactivity of MnPc Versus MnTPP
Electrocatalysis, 2019Co-Authors: Vellaichamy Ganesan, Elena Madrid, Richard Malpass-evans, Mariolino Carta, Neil B. Mckeown, Frank MarkenAbstract:A hydrophobic polymer of intrinsic microporosity (PIM-EA-TB) is employed to stabilize an organogel/aqueous electrolyte phase boundary based on an organic water-insoluble 4-(3-phenylpropyl)-pyridine phase. The organogel with electrocatalytic metal complexes embedded is immobilized on glassy carbon or on transparent mesoporous tin-doped indium oxide (ITO) electrodes. Liquid/liquid ion transfer voltammetry is investigated for a 4-(3-phenylpropyl)-pyridine organogel/aqueous electrolyte interface for two types of Redox Systems: tetraphenylporphyrinato-Mn(III/II) (MnTPP) and phthalocyanato-Mn(III/II) (MnPc). Electron transfer is shown to be coupled to reversible liquid/liquid anion transfer processes for PF_6^−, ClO_4^−, SCN^−, and NO_3^−, with a change in mechanism for the more hydrophilic anions Cl^−, F^−, and SO_4^2−. In situ UV-Vis spectroelectrochemistry reveals reversible Mn(III/II) Redox processes coupled to ion transfer for MnTPP. But further complexity and a detrimental side reaction are observed for MnPc causing gradual loss of the electrochemical response in the presence of dioxygen. Graphical Abstract ᅟ
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ITO-ITO Dual-Plate Microgap Electrodes: E and EC′ Generator-Collector Processes
Electroanalysis, 2015Co-Authors: Andrew James Gross, Frank MarkenAbstract:Tin-doped indium oxide electrodes are fabricated and employed in a dual-plate microtrench geometry with the inter-electrode gap controlling the mass transport conditions in generator-collector mode. Electrodes are fabricated with 2–50 µm gap sizes and variable trench depths by controlling assembly parameters. Non-ideal behaviour is observed for three aqueous Redox Systems: Ru(bpy) equation image, 1,1′-ferrocenedimethanol and Ru(NH3). Under fast mass transport conditions, the former two Systems exhibit slower oxidation features. For Ru(NH3), non-steady-state behaviour is observed due to irreversible (ECirrev′) consumption of oxygen in the microtrench. A mechanism leading to hydrogen peroxide formation via superoxide in Ru(NH3) solution is proposed. Under optimised conditions all three Redox Systems provide reliable trench depth calibration information.
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Electro-deposition of thin cellulose films at boron-doped diamond substrates
Electrochemistry Communications, 2006Co-Authors: Michael J. Bonné, Matthew Helton, Karen J Edler, Frank MarkenAbstract:Cellulose films of variable thickness are electro-deposited from aqueous alkaline thiourea solution onto polished boron-doped diamond substrates in an anodic process. Films with “net-like” topography are formed and shown to consist of both cellulose-I and cellulose-II components. Properties of these films are investigated. When immersed in aqueous electrolyte solution, ion partitioning into the electro-deposited cellulose films occurs. The accumulation and release of two aqueous Redox Systems, Ru(NH3)63+/2+ and methylviologen2+/+, is reported. Relatively slow diffusion of these cations is observed within cellulose (approximately 5 orders of magnitude slower when compared to diffusion in aqueous media). For the methylviologen2+/+ Redox system partitioning leads to irreversibility in the voltammetric response and to the preferred formation of aggregates immobilized within the cellulose film.
Akira Fujishima - One of the best experts on this subject based on the ideXlab platform.
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Electrochemical selectivity for Redox Systems at oxygen-terminated diamond electrodes
Journal of Electroanalytical Chemistry, 1999Co-Authors: Ichizo Yagi, Hideo Notsu, Donald A. Tryk, Takeshi Kondo, Akira FujishimaAbstract:Oxygen-terminated diamond electrodes were prepared by exposing as-grown hydrogen-terminated diamond thin films to oxygen plasma. The as-grown surfaces, which were highly hydrophobic, become hydrophilic after the oxygen plasma treatment. The apparent surface conductivity was not significantly changed after the oxygen plasma treatment. However, the electrochemical responses to several Redox Systems became remarkably different. For example, the cyclic voltammetric anodic-cathodic peak separations for the oxygen-terminated diamond electrodes became extremely large compared to those for the as-grown electrodes. This behavior was examined in comparison with as-grown diamond and glassy carbon electrodes.
