The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
Shulin Chen - One of the best experts on this subject based on the ideXlab platform.
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tetramethylammonium hydroxide tmah thermochemolysis for probing in situ softwood lignin modification in each gut segment of the termite
Journal of Agricultural and Food Chemistry, 2013Co-Authors: Dhrubojyoti D Laskar, Shulin ChenAbstract:Termites are highly effective in lignocellulose degradation; however, the process of lignin deconstruction along the alimentary canal is not well understood. In this study, the wood metabolites in each gut segment were tentatively analyzed using pyrolysis–gas chromatography–mass spectrometry in the presence of tetramethylammonium hydroxide. Collectively, the significant differences in the pyrolysate distribution among each sample established (1) conservation of the major β-O-4′ bonds of lignin during termite digestion, although a selective lignin substructure modification was observed across the whole gut; (2) initiation of lignin–polysaccharide dissociation, aliphatic oxidation/Carboxylation, phenolic dehydroxylation in the foregut, and linkage modification of the 5-5′, β-5′, and β-1′ substructures; (3) the continuation of foregut reactions into the midgut with further phenolic Carboxylation/demethoxylation/carbonylation; and (4) phenolic/aliphatic esterifications in the hindgut. Overall, elucidation of ...
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Tetramethylammonium hydroxide (TMAH) thermochemolysis for probing in situ softwood lignin modification in each gut segment of the termite.
Journal of agricultural and food chemistry, 2013Co-Authors: Dhrubojyoti D Laskar, Shulin ChenAbstract:Termites are highly effective in lignocellulose degradation; however, the process of lignin deconstruction along the alimentary canal is not well understood. In this study, the wood metabolites in each gut segment were tentatively analyzed using pyrolysis-gas chromatography-mass spectrometry in the presence of tetramethylammonium hydroxide. Collectively, the significant differences in the pyrolysate distribution among each sample established (1) conservation of the major β-O-4' bonds of lignin during termite digestion, although a selective lignin substructure modification was observed across the whole gut; (2) initiation of lignin-polysaccharide dissociation, aliphatic oxidation/Carboxylation, phenolic dehydroxylation in the foregut, and linkage modification of the 5-5', β-5', and β-1' substructures; (3) the continuation of foregut reactions into the midgut with further phenolic Carboxylation/demethoxylation/carbonylation; and (4) phenolic/aliphatic esterifications in the hindgut. Overall, elucidation of the stepwise lignin unlocking mechanism in termites provides a valuable insight for understanding plant cell wall structure and its recalcitrance.
Jianhai Du - One of the best experts on this subject based on the ideXlab platform.
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reductive Carboxylation is a major metabolic pathway in the retinal pigment epithelium
Proceedings of the National Academy of Sciences of the United States of America, 2016Co-Authors: Jianhai Du, Aya Yanagida, Kaitlen Knight, Abbi L Engel, Anh Huan Vo, Connor Jankowski, Martin Sadilek, Van Tran, Megan MansonAbstract:The retinal pigment epithelium (RPE) is a monolayer of pigmented cells that requires an active metabolism to maintain outer retinal homeostasis and compensate for oxidative stress. Using 13C metabolic flux analysis in human RPE cells, we found that RPE has an exceptionally high capacity for reductive Carboxylation, a metabolic pathway that has recently garnered significant interest because of its role in cancer cell survival. The capacity for reductive Carboxylation in RPE exceeds that of all other cells tested, including retina, neural tissue, glial cells, and a cancer cell line. Loss of reductive Carboxylation disrupts redox balance and increases RPE sensitivity to oxidative damage, suggesting that deficiencies of reductive Carboxylation may contribute to RPE cell death. Supporting reductive Carboxylation by supplementation with an NAD+ precursor or its substrate α-ketoglutarate or treatment with a poly(ADP ribose) polymerase inhibitor protects reductive Carboxylation and RPE viability from excessive oxidative stress. The ability of these treatments to rescue RPE could be the basis for an effective strategy to treat blinding diseases caused by RPE dysfunction.
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reductive Carboxylation is a major metabolic pathway in the retinal pigment epithelium
Proceedings of the National Academy of Sciences of the United States of America, 2016Co-Authors: Jianhai Du, Aya Yanagida, Kaitlen Knight, Abbi L Engel, Anh Huan Vo, Connor Jankowski, Martin Sadilek, Van Tran, Megan MansonAbstract:The retinal pigment epithelium (RPE) is a monolayer of pigmented cells that requires an active metabolism to maintain outer retinal homeostasis and compensate for oxidative stress. Using 13C metabolic flux analysis in human RPE cells, we found that RPE has an exceptionally high capacity for reductive Carboxylation, a metabolic pathway that has recently garnered significant interest because of its role in cancer cell survival. The capacity for reductive Carboxylation in RPE exceeds that of all other cells tested, including retina, neural tissue, glial cells, and a cancer cell line. Loss of reductive Carboxylation disrupts redox balance and increases RPE sensitivity to oxidative damage, suggesting that deficiencies of reductive Carboxylation may contribute to RPE cell death. Supporting reductive Carboxylation by supplementation with an NAD+ precursor or its substrate α-ketoglutarate or treatment with a poly(ADP ribose) polymerase inhibitor protects reductive Carboxylation and RPE viability from excessive oxidative stress. The ability of these treatments to rescue RPE could be the basis for an effective strategy to treat blinding diseases caused by RPE dysfunction.
Arantxa Eceiza - One of the best experts on this subject based on the ideXlab platform.
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The effect of the Carboxylation degree on cellulose nanofibers and waterborne polyurethane/cellulose nanofiber nanocomposites properties
Polymer Degradation and Stability, 2020Co-Authors: Izaskun Larraza, Julen Vadillo, Arantzazu Santamaria-echart, Alvaro Tejado, Maider Azpeitia, Eneritz Vesga, Ander Orue, Ainara Saralegi, Aitor Arbelaiz, Arantxa EceizaAbstract:There has been an exponential rise in the interest for waterborne polyurethanes (WBPU), due to the easy customizability of their properties and their ecofriendly nature. Moreover, their aqueous state facilitates the incorporation of hydrophilic reinforcements. Cellulose nanofibers (CNFs) have shown great potential, thanks to their renewability, large natural availability, low cost and great specific properties. However, CNFs often require some modification to obtain optimal compatibility. In this work, standard bleached hardwood kraft pulp has been subjected to a Carboxylation process followed by mechanical disintegration. Varying treatment times and passes, CNF samples with different Carboxylation degrees have been obtained. WBPU/CNF nanocomposites with different CNF content have been prepared. The effect of the Carboxylation degree on the CNFs and on the nanocomposites properties has been studied. Although Carboxylation damaged the cellulose structure, decreasing the crystallinity degree of CNF and reducing the thermal stability of fibers, composites showed better thermal and thermomechanical stability and improved mechanical properties than the unreinforced matrix counterpart. A maximum increase of 1670% in modulus, 377% in stress at yield and 86% in stress at break has been achieved for composites reinforced with carboxylated fibers. Therefore, it was observed that Carboxylation improved matrix/reinforcement interactions.
Megan Manson - One of the best experts on this subject based on the ideXlab platform.
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reductive Carboxylation is a major metabolic pathway in the retinal pigment epithelium
Proceedings of the National Academy of Sciences of the United States of America, 2016Co-Authors: Jianhai Du, Aya Yanagida, Kaitlen Knight, Abbi L Engel, Anh Huan Vo, Connor Jankowski, Martin Sadilek, Van Tran, Megan MansonAbstract:The retinal pigment epithelium (RPE) is a monolayer of pigmented cells that requires an active metabolism to maintain outer retinal homeostasis and compensate for oxidative stress. Using 13C metabolic flux analysis in human RPE cells, we found that RPE has an exceptionally high capacity for reductive Carboxylation, a metabolic pathway that has recently garnered significant interest because of its role in cancer cell survival. The capacity for reductive Carboxylation in RPE exceeds that of all other cells tested, including retina, neural tissue, glial cells, and a cancer cell line. Loss of reductive Carboxylation disrupts redox balance and increases RPE sensitivity to oxidative damage, suggesting that deficiencies of reductive Carboxylation may contribute to RPE cell death. Supporting reductive Carboxylation by supplementation with an NAD+ precursor or its substrate α-ketoglutarate or treatment with a poly(ADP ribose) polymerase inhibitor protects reductive Carboxylation and RPE viability from excessive oxidative stress. The ability of these treatments to rescue RPE could be the basis for an effective strategy to treat blinding diseases caused by RPE dysfunction.
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reductive Carboxylation is a major metabolic pathway in the retinal pigment epithelium
Proceedings of the National Academy of Sciences of the United States of America, 2016Co-Authors: Jianhai Du, Aya Yanagida, Kaitlen Knight, Abbi L Engel, Anh Huan Vo, Connor Jankowski, Martin Sadilek, Van Tran, Megan MansonAbstract:The retinal pigment epithelium (RPE) is a monolayer of pigmented cells that requires an active metabolism to maintain outer retinal homeostasis and compensate for oxidative stress. Using 13C metabolic flux analysis in human RPE cells, we found that RPE has an exceptionally high capacity for reductive Carboxylation, a metabolic pathway that has recently garnered significant interest because of its role in cancer cell survival. The capacity for reductive Carboxylation in RPE exceeds that of all other cells tested, including retina, neural tissue, glial cells, and a cancer cell line. Loss of reductive Carboxylation disrupts redox balance and increases RPE sensitivity to oxidative damage, suggesting that deficiencies of reductive Carboxylation may contribute to RPE cell death. Supporting reductive Carboxylation by supplementation with an NAD+ precursor or its substrate α-ketoglutarate or treatment with a poly(ADP ribose) polymerase inhibitor protects reductive Carboxylation and RPE viability from excessive oxidative stress. The ability of these treatments to rescue RPE could be the basis for an effective strategy to treat blinding diseases caused by RPE dysfunction.
Marilyn A Huestis - One of the best experts on this subject based on the ideXlab platform.
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First metabolic profile of PV8, a novel synthetic cathinone, in human hepatocytes and urine by high-resolution mass spectrometry
Analytical and Bioanalytical Chemistry, 2016Co-Authors: Madeleine J Swortwood, Kayla N Ellefsen, Ariane Wohlfarth, Xingxing Diao, Robert Kronstrand, Marta Concheiro-guisan, Marilyn A HuestisAbstract:Novel psychoactive substances (NPS) are ever changing on the drug market, making it difficult for toxicology laboratory methods to stay current with so many new drugs. Recently, PV8, a synthetic pyrrolidinophenone, was detected in seized products in Japan (2013), The Netherlands (2014), and Germany (2014). There are no controlled PV8 administration studies, and no pharmacodynamic and pharmacokinetic data. The objective was to determine PV8’s metabolic stability in human liver microsome (HLM) incubation and its metabolism following human hepatocyte incubation and high-resolution mass spectrometry (HRMS) with a Thermo Scientific Q-Exactive. Data were acquired with a full-scan data-dependent mass spectrometry method. Scans were thoroughly data mined with different data processing algorithms and analyzed in WebMetaBase. PV8 exhibited a relatively short 28.8 min half-life, with an intrinsic 24.2 μL/min/mg microsomal clearance. This compound is predicted to be an intermediate clearance drug with an estimated human 22.7 mL/min/kg hepatic clearance. Metabolic pathways identified in vitro included: hydroxylation, ketone reduction, Carboxylation, N -dealkylation, iminium formation, dehydrogenation, N -oxidation, and carbonylation. The top three in vitro metabolic pathways were di-hydroxylation > ketone reduction > γ-lactam formation. Authentic urine specimen analyses revealed the top three metabolic pathways were aliphatic hydroxylation > ketone reduction + aliphatic hydroxylation > aliphatic Carboxylation, although the most prominent peak was parent PV8. These data provide useful urinary metabolite targets (aliphatic hydroxylation, aliphatic hydroxylation + ketone reduction, aliphatic Carboxylation, and di-hydroxylation) for forensic and clinical testing, and focus reference standard companies’ synthetic efforts to provide commercially available standards needed for PV8 biological specimen testing. Graphical Abstract Top four PV8 metabolites identified in vitro. Biotransformations highlighted in blue. Markush structures presented when exact location of biotransformation is unknown
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first metabolic profile of pv8 a novel synthetic cathinone in human hepatocytes and urine by high resolution mass spectrometry
Analytical and Bioanalytical Chemistry, 2016Co-Authors: Madeleine J Swortwood, Kayla N Ellefsen, Ariane Wohlfarth, Xingxing Diao, Marta Concheiroguisan, Robert Kronstrand, Marilyn A HuestisAbstract:Novel psychoactive substances (NPS) are ever changing on the drug market, making it difficult for toxicology laboratory methods to stay current with so many new drugs. Recently, PV8, a synthetic pyrrolidinophenone, was detected in seized products in Japan (2013), The Netherlands (2014), and Germany (2014). There are no controlled PV8 administration studies, and no pharmacodynamic and pharmacokinetic data. The objective was to determine PV8’s metabolic stability in human liver microsome (HLM) incubation and its metabolism following human hepatocyte incubation and high-resolution mass spectrometry (HRMS) with a Thermo Scientific Q-Exactive. Data were acquired with a full-scan data-dependent mass spectrometry method. Scans were thoroughly data mined with different data processing algorithms and analyzed in WebMetaBase. PV8 exhibited a relatively short 28.8 min half-life, with an intrinsic 24.2 μL/min/mg microsomal clearance. This compound is predicted to be an intermediate clearance drug with an estimated human 22.7 mL/min/kg hepatic clearance. Metabolic pathways identified in vitro included: hydroxylation, ketone reduction, Carboxylation, N-dealkylation, iminium formation, dehydrogenation, N-oxidation, and carbonylation. The top three in vitro metabolic pathways were di-hydroxylation > ketone reduction > γ-lactam formation. Authentic urine specimen analyses revealed the top three metabolic pathways were aliphatic hydroxylation > ketone reduction + aliphatic hydroxylation > aliphatic Carboxylation, although the most prominent peak was parent PV8. These data provide useful urinary metabolite targets (aliphatic hydroxylation, aliphatic hydroxylation + ketone reduction, aliphatic Carboxylation, and di-hydroxylation) for forensic and clinical testing, and focus reference standard companies’ synthetic efforts to provide commercially available standards needed for PV8 biological specimen testing.