The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Michael A Rogawski - One of the best experts on this subject based on the ideXlab platform.
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ALLOSTERIC REGULATION OF Æ-AMINO-3-HYDROXY-5-METHYL-4-ISOXAZOLE-PROPIONATE RECEPTORS BY THIOCYANATE AND CYCLOTHIAZIDE AT A COMMON MODULATORY SITE DISTINCT FROM THAT OF 2,3-BENZODIAZEPINES
2016Co-Authors: Sean D Donevan, Michael A RogawskiAbstract:Abstract––Allosteric regulators of Æ-amino-3-hydroxy-5-methyl-4-isoxazole-propionate (AMPA) recep-tors include 2,3-benzodiazepines such as GYKI 52466 and GYKI 53655 and the chaotropic anion thiocyanate that inhibit, and benzothiadiazines such as cyclothiazide that potentiate AMPA receptor currents. Here we sought to determine whether the allosteric regulators modulate AMPA receptors at a common or distinct allosteric sites by comparing their actions on AMPA- and kainate-evoked currents in cultured rat hippocampal neurons and Xenopus oocytes expressing recombinant AMPA receptor subunits. GYKI 52466 and thiocyanate blocked AMPA-evoked currents in a concentration-dependent manner (IC50 values, 8.2 µM and 1.1 mM, respectively); in contrast, kainate-evoked currents were blocked by GYKI 52466, but were potentiated by high concentrations of thiocyanate (§3 mM). Thiocyanate enhanced the rate of desensitization and slowed recovery from desensitization of AMPA-evoked currents, whereas GYKI 52466 failed to aVect desensitization. Among neurons in the hippocampal cultures, there was cell-to-cell variability in the sensitivity to block of AMPA-evoked currents by thiocyanate that was correlated with the degree of potentiation by cyclothiazide. Moreover, cyclothiazide caused a parallel rightward shift in the concentration–response curve for thiocyanate block, and slowed the onset of thiocyanate block to a rate that was similar to that of cyclothiazide dissociation. Together, thes
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allosteric regulation of α amino 3 hydroxy 5 methyl 4 isoxazole propionate receptors by thiocyanate and cyclothiazide at a common modulatory site distinct from that of 2 3 benzodiazepines
Neuroscience, 1998Co-Authors: Sean D Donevan, Michael A RogawskiAbstract:Abstract Allosteric regulators of α-amino-3-hydroxy-5-methyl-4-isoxazole-propionate (AMPA) receptors include 2,3-benzodiazepines such as GYKI 52466 and GYKI 53655 and the chaotropic anion thiocyanate that inhibit, and benzothiadiazines such as cyclothiazide that potentiate AMPA receptor currents. Here we sought to determine whether the allosteric regulators modulate AMPA receptors at a common or distinct allosteric sites by comparing their actions on AMPA- and kainate-evoked currents in cultured rat hippocampal neurons and Xenopus oocytes expressing recombinant AMPA receptor subunits. GYKI 52466 and thiocyanate blocked AMPA-evoked currents in a concentration-dependent manner (IC 50 values, 8.2 μM and 1.1 mM, respectively); in contrast, kainate-evoked currents were blocked by GYKI 52466, but were potentiated by high concentrations of thiocyanate (≥3 mM). Thiocyanate enhanced the rate of desensitization and slowed recovery from desensitization of AMPA-evoked currents, whereas GYKI 52466 failed to affect desensitization. Among neurons in the hippocampal cultures, there was cell-to-cell variability in the sensitivity to block of AMPA-evoked currents by thiocyanate that was correlated with the degree of potentiation by cyclothiazide. Moreover, cyclothiazide caused a parallel rightward shift in the concentration–response curve for thiocyanate block, and slowed the onset of thiocyanate block to a rate that was similar to that of cyclothiazide dissociation. Together, these observations suggest that thiocyanate and cyclothiazide act at non-distinct allosteric sites. GYKI 52466 blocked AMPA receptor responses to a similar extent, irrespective of the degree of cyclothiazide potentiation. Moreover, the kinetics of GYKI 53655 block in the presence of cyclothiazide were not consistent with a competitive interaction. As is the case for cyclothiazide, SCN − exhibited greater affinity for flip than for flop AMPA receptor splice variants. In particular, GluR1 flip /GluR2 flip was especially sensitive to thiocyanate block. We conclude that thiocyanate, a flip -preferring allosteric modulator like cyclothiazide, appears to act by enhancing desensitization at a site that may overlap the site where cyclothiazide reduces desensitization, whereas 2,3-benzodiazepines act at a distinct site and the block does not involve a modification of desensitization.
Saaid Karimian - One of the best experts on this subject based on the ideXlab platform.
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1 methyl 3 2 sulfooxy ethyl 1h imidazol 3 ium thiocyanate as a novel green and efficient bronsted acidic ionic liquid promoted regioselective thiocyanation of aromatic and heteroaromatic compounds at room temperature
Phosphorus Sulfur and Silicon and The Related Elements, 2014Co-Authors: Sami Sajjadifar, Saied Ahmadaghaee, Eshagh Rezaee Nezhad, Hossein Hosseinzadeh, Saaid KarimianAbstract:Abstract An efficient and simple method for the preparation of 1-methyl-3-(2-(sulfooxy)ethyl)-1H-imidazol-3-ium thiocyanate ([Msei]SCN) as a Bronsted acidic ionic liquid (BAIL) is described, and it is used in the highly efficient regioselective thiocyanation of aromatic and heteroaromatic compounds via a green and simple protocol. [Msei]SCN as a novel IL and thiocyanation agent, H2O2 as a mild and environmentally friendly oxidant, and H2O:ethanol(1:4) as a solvent were used. This procedure provided the target Thiocyanates in high yield and very short reaction time. [Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental files: Additional figures.]
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1 methyl 3 2 sulfooxy ethyl 1h imidazol 3 ium thiocyanate as a novel green and efficient bronsted acidic ionic liquid promoted regioselective thiocyanation of aromatic and heteroaromatic compounds at room temperature
Phosphorus Sulfur and Silicon and The Related Elements, 2014Co-Authors: Sami Sajjadifar, Saied Ahmadaghaee, Eshagh Rezaee Nezhad, Hossein Hosseinzadeh, Saaid KarimianAbstract:Abstract An efficient and simple method for the preparation of 1-methyl-3-(2-(sulfooxy)ethyl)-1H-imidazol-3-ium thiocyanate ([Msei]SCN) as a Bronsted acidic ionic liquid (BAIL) is described, and it is used in the highly efficient regioselective thiocyanation of aromatic and heteroaromatic compounds via a green and simple protocol. [Msei]SCN as a novel IL and thiocyanation agent, H2O2 as a mild and environmentally friendly oxidant, and H2O:ethanol(1:4) as a solvent were used. This procedure provided the target Thiocyanates in high yield and very short reaction time. [Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental files: Additional figures.]
Sean D Donevan - One of the best experts on this subject based on the ideXlab platform.
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ALLOSTERIC REGULATION OF Æ-AMINO-3-HYDROXY-5-METHYL-4-ISOXAZOLE-PROPIONATE RECEPTORS BY THIOCYANATE AND CYCLOTHIAZIDE AT A COMMON MODULATORY SITE DISTINCT FROM THAT OF 2,3-BENZODIAZEPINES
2016Co-Authors: Sean D Donevan, Michael A RogawskiAbstract:Abstract––Allosteric regulators of Æ-amino-3-hydroxy-5-methyl-4-isoxazole-propionate (AMPA) recep-tors include 2,3-benzodiazepines such as GYKI 52466 and GYKI 53655 and the chaotropic anion thiocyanate that inhibit, and benzothiadiazines such as cyclothiazide that potentiate AMPA receptor currents. Here we sought to determine whether the allosteric regulators modulate AMPA receptors at a common or distinct allosteric sites by comparing their actions on AMPA- and kainate-evoked currents in cultured rat hippocampal neurons and Xenopus oocytes expressing recombinant AMPA receptor subunits. GYKI 52466 and thiocyanate blocked AMPA-evoked currents in a concentration-dependent manner (IC50 values, 8.2 µM and 1.1 mM, respectively); in contrast, kainate-evoked currents were blocked by GYKI 52466, but were potentiated by high concentrations of thiocyanate (§3 mM). Thiocyanate enhanced the rate of desensitization and slowed recovery from desensitization of AMPA-evoked currents, whereas GYKI 52466 failed to aVect desensitization. Among neurons in the hippocampal cultures, there was cell-to-cell variability in the sensitivity to block of AMPA-evoked currents by thiocyanate that was correlated with the degree of potentiation by cyclothiazide. Moreover, cyclothiazide caused a parallel rightward shift in the concentration–response curve for thiocyanate block, and slowed the onset of thiocyanate block to a rate that was similar to that of cyclothiazide dissociation. Together, thes
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allosteric regulation of α amino 3 hydroxy 5 methyl 4 isoxazole propionate receptors by thiocyanate and cyclothiazide at a common modulatory site distinct from that of 2 3 benzodiazepines
Neuroscience, 1998Co-Authors: Sean D Donevan, Michael A RogawskiAbstract:Abstract Allosteric regulators of α-amino-3-hydroxy-5-methyl-4-isoxazole-propionate (AMPA) receptors include 2,3-benzodiazepines such as GYKI 52466 and GYKI 53655 and the chaotropic anion thiocyanate that inhibit, and benzothiadiazines such as cyclothiazide that potentiate AMPA receptor currents. Here we sought to determine whether the allosteric regulators modulate AMPA receptors at a common or distinct allosteric sites by comparing their actions on AMPA- and kainate-evoked currents in cultured rat hippocampal neurons and Xenopus oocytes expressing recombinant AMPA receptor subunits. GYKI 52466 and thiocyanate blocked AMPA-evoked currents in a concentration-dependent manner (IC 50 values, 8.2 μM and 1.1 mM, respectively); in contrast, kainate-evoked currents were blocked by GYKI 52466, but were potentiated by high concentrations of thiocyanate (≥3 mM). Thiocyanate enhanced the rate of desensitization and slowed recovery from desensitization of AMPA-evoked currents, whereas GYKI 52466 failed to affect desensitization. Among neurons in the hippocampal cultures, there was cell-to-cell variability in the sensitivity to block of AMPA-evoked currents by thiocyanate that was correlated with the degree of potentiation by cyclothiazide. Moreover, cyclothiazide caused a parallel rightward shift in the concentration–response curve for thiocyanate block, and slowed the onset of thiocyanate block to a rate that was similar to that of cyclothiazide dissociation. Together, these observations suggest that thiocyanate and cyclothiazide act at non-distinct allosteric sites. GYKI 52466 blocked AMPA receptor responses to a similar extent, irrespective of the degree of cyclothiazide potentiation. Moreover, the kinetics of GYKI 53655 block in the presence of cyclothiazide were not consistent with a competitive interaction. As is the case for cyclothiazide, SCN − exhibited greater affinity for flip than for flop AMPA receptor splice variants. In particular, GluR1 flip /GluR2 flip was especially sensitive to thiocyanate block. We conclude that thiocyanate, a flip -preferring allosteric modulator like cyclothiazide, appears to act by enhancing desensitization at a site that may overlap the site where cyclothiazide reduces desensitization, whereas 2,3-benzodiazepines act at a distinct site and the block does not involve a modification of desensitization.
Witold Danikiewicz - One of the best experts on this subject based on the ideXlab platform.
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gas phase reactions of methyl thiocyanate with aliphatic carbanions a mass spectrometry and computational study
Rapid Communications in Mass Spectrometry, 2016Co-Authors: Barbara Repec, Kacper Blaziak, Witold DanikiewiczAbstract:Rationale Methyl thiocyanate, like other organic Thiocyanates, is a molecule with many electrophilic reactive sites and it has many synthetic applications. For better understanding of the intrinsic reactivity of alkyl Thiocyanates against nucleophiles it was important to study gas-phase reactions of methyl thiocyanate with carbanions differing by structure and proton affinity values. Methods All experiments were performed using a modified API 365 triple quadrupole mass spectrometer equipped with a TurboIonSpray electrospray ionization (ESI) source. Carbanions were generated in the ESI source by decarboxylation of the respective carboxylic acid anions. Methyl thiocyanate was delivered as a vapor with nitrogen used as a collision gas to the collision cell where the reactions take place. Results Mass spectra recorded for the gas-phase reactions of five aliphatic carbanions with methyl thiocyanate showed a variety of product ions formed via different reaction mechanisms, depending on the structure and proton affinity of the carbanion. The pathways considered are: SN2 nucleophilic substitution, cyanophilic reaction, thiophilic reaction and proton transfer, followed in some instances by subsequent transformations. The proposed reaction pathways are supported by density functional theory (DFT) calculations. Conclusions Our preliminary experiments showed that mass spectrometry together with quantum chemical calculations is a good tool for studying gas-phase reactions of alkyl Thiocyanates with carbanions. In the gas phase all four theoretically possible products can be observed and their formation can be rationalized by the results of the modelling of the reaction energy profiles. Copyright © 2016 John Wiley & Sons, Ltd.
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gas phase reactions of methyl thiocyanate with aliphatic carbanions a mass spectrometry and computational study
Rapid Communications in Mass Spectrometry, 2016Co-Authors: Barbara Repec, Kacper Blaziak, Witold DanikiewiczAbstract:Rationale Methyl thiocyanate, like other organic Thiocyanates, is a molecule with many electrophilic reactive sites and it has many synthetic applications. For better understanding of the intrinsic reactivity of alkyl Thiocyanates against nucleophiles it was important to study gas-phase reactions of methyl thiocyanate with carbanions differing by structure and proton affinity values. Methods All experiments were performed using a modified API 365 triple quadrupole mass spectrometer equipped with a TurboIonSpray electrospray ionization (ESI) source. Carbanions were generated in the ESI source by decarboxylation of the respective carboxylic acid anions. Methyl thiocyanate was delivered as a vapor with nitrogen used as a collision gas to the collision cell where the reactions take place. Results Mass spectra recorded for the gas-phase reactions of five aliphatic carbanions with methyl thiocyanate showed a variety of product ions formed via different reaction mechanisms, depending on the structure and proton affinity of the carbanion. The pathways considered are: SN2 nucleophilic substitution, cyanophilic reaction, thiophilic reaction and proton transfer, followed in some instances by subsequent transformations. The proposed reaction pathways are supported by density functional theory (DFT) calculations. Conclusions Our preliminary experiments showed that mass spectrometry together with quantum chemical calculations is a good tool for studying gas-phase reactions of alkyl Thiocyanates with carbanions. In the gas phase all four theoretically possible products can be observed and their formation can be rationalized by the results of the modelling of the reaction energy profiles. Copyright © 2016 John Wiley & Sons, Ltd.
Sami Sajjadifar - One of the best experts on this subject based on the ideXlab platform.
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1 methyl 3 2 sulfooxy ethyl 1h imidazol 3 ium thiocyanate as a novel green and efficient bronsted acidic ionic liquid promoted regioselective thiocyanation of aromatic and heteroaromatic compounds at room temperature
Phosphorus Sulfur and Silicon and The Related Elements, 2014Co-Authors: Sami Sajjadifar, Saied Ahmadaghaee, Eshagh Rezaee Nezhad, Hossein Hosseinzadeh, Saaid KarimianAbstract:Abstract An efficient and simple method for the preparation of 1-methyl-3-(2-(sulfooxy)ethyl)-1H-imidazol-3-ium thiocyanate ([Msei]SCN) as a Bronsted acidic ionic liquid (BAIL) is described, and it is used in the highly efficient regioselective thiocyanation of aromatic and heteroaromatic compounds via a green and simple protocol. [Msei]SCN as a novel IL and thiocyanation agent, H2O2 as a mild and environmentally friendly oxidant, and H2O:ethanol(1:4) as a solvent were used. This procedure provided the target Thiocyanates in high yield and very short reaction time. [Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental files: Additional figures.]
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1 methyl 3 2 sulfooxy ethyl 1h imidazol 3 ium thiocyanate as a novel green and efficient bronsted acidic ionic liquid promoted regioselective thiocyanation of aromatic and heteroaromatic compounds at room temperature
Phosphorus Sulfur and Silicon and The Related Elements, 2014Co-Authors: Sami Sajjadifar, Saied Ahmadaghaee, Eshagh Rezaee Nezhad, Hossein Hosseinzadeh, Saaid KarimianAbstract:Abstract An efficient and simple method for the preparation of 1-methyl-3-(2-(sulfooxy)ethyl)-1H-imidazol-3-ium thiocyanate ([Msei]SCN) as a Bronsted acidic ionic liquid (BAIL) is described, and it is used in the highly efficient regioselective thiocyanation of aromatic and heteroaromatic compounds via a green and simple protocol. [Msei]SCN as a novel IL and thiocyanation agent, H2O2 as a mild and environmentally friendly oxidant, and H2O:ethanol(1:4) as a solvent were used. This procedure provided the target Thiocyanates in high yield and very short reaction time. [Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental files: Additional figures.]
