2010
|
Striking Inflammation from Both Sides: Manganese(II) Pentaazamacrocyclic SOD Mimics Act Also as Nitric Oxide Dismutases: A Single-Cell Study Article de journal Milos R Filipovic; Alaric C W Koh; Stephane Arbault; Vesna Niketic; Andrea Debus; Ulrike Schleicher; Christian Bogdan; Manon Guille; Frederic Lemaitre; Christian Amatore; Ivana Ivanovic-Burmazovic Angewandte Chemie-International Edition, 49 (25), p. 4228-4232, 2010, ISSN: 1433-7851. @article{RN23b,
title = {Striking Inflammation from Both Sides: Manganese(II) Pentaazamacrocyclic SOD Mimics Act Also as Nitric Oxide Dismutases: A Single-Cell Study},
author = {Milos R Filipovic and Alaric C W Koh and Stephane Arbault and Vesna Niketic and Andrea Debus and Ulrike Schleicher and Christian Bogdan and Manon Guille and Frederic Lemaitre and Christian Amatore and Ivana {Ivanovic-Burmazovic}},
doi = {10.1002/anie.200905936},
issn = {1433-7851},
year = {2010},
date = {2010-01-01},
journal = {Angewandte Chemie-International Edition},
volume = {49},
number = {25},
pages = {4228-4232},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
2009
|
Invariance of exocytotic events detected by amperometry as a function of the carbon fiber microelectrode diameter Article de journal C Amatore; S Arbault; Y Bouret; M Guille; F Lemaître; Y Verchier Analytical Chemistry, 81 (8), p. 3087–3093, 2009. @article{Amatore:2009e,
title = {Invariance of exocytotic events detected by amperometry as a function of the carbon fiber microelectrode diameter},
author = {C Amatore and S Arbault and Y Bouret and M Guille and F Lema\^{i}tre and Y Verchier},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-65249125788&doi=10.1021%2fac900059s&partnerID=40&md5=3a9131b641fb9496ef04b7576ed24617},
doi = {10.1021/ac900059s},
year = {2009},
date = {2009-01-01},
journal = {Analytical Chemistry},
volume = {81},
number = {8},
pages = {3087--3093},
abstract = {Etched carbon fiber microelectrodes of different radii have been used for amperometric measurements of single exocytotic events occurring at adrenal chromaffin cells. Frequency, kinetic, and quantitative information on exo-cytosis provided by amperometric spikes were analyzed as a function of the surface area of the microelectrodes. Interestingly, the percentage of spikes with foot (as well as their own characteristics), a category revealing the existence of sufficient long-lasting fusion pores, was found to be constant whatever the microelectrode diameter was, whereas the probability of overlapping spikes decreased with the electrode size. This confirmed that the prespike foot could not feature accidental superimposition of separated events occurring at different places. Moreover, the features of amperometric spikes investigated here (charge, intensity and kinetics) were found constant for all microelectrode diameters. This demonstrated that the electrochemical measurement does not introduce significant bias onto the kinetics and thermodynamics of release during individual exocytotic events. All in all, this work evidences that information on exocytosis amperometri-cally recorded with the usual 7 μm diameter carbon fiber electrodes is biologically relevant, although the frequent overlap between spikes requires a censorship of the data during the analytical treatment. © 2009 American Chemical Society.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Etched carbon fiber microelectrodes of different radii have been used for amperometric measurements of single exocytotic events occurring at adrenal chromaffin cells. Frequency, kinetic, and quantitative information on exo-cytosis provided by amperometric spikes were analyzed as a function of the surface area of the microelectrodes. Interestingly, the percentage of spikes with foot (as well as their own characteristics), a category revealing the existence of sufficient long-lasting fusion pores, was found to be constant whatever the microelectrode diameter was, whereas the probability of overlapping spikes decreased with the electrode size. This confirmed that the prespike foot could not feature accidental superimposition of separated events occurring at different places. Moreover, the features of amperometric spikes investigated here (charge, intensity and kinetics) were found constant for all microelectrode diameters. This demonstrated that the electrochemical measurement does not introduce significant bias onto the kinetics and thermodynamics of release during individual exocytotic events. All in all, this work evidences that information on exocytosis amperometri-cally recorded with the usual 7 μm diameter carbon fiber electrodes is biologically relevant, although the frequent overlap between spikes requires a censorship of the data during the analytical treatment. © 2009 American Chemical Society. |
2008
|
Electrochemical monitoring of single cell secretion: Vesicular exocytosis and oxidative stress Article de journal C Amatore; S Arbault; M Guille; F Lemaître Chemical Reviews, 108 (7), p. 2585–2621, 2008. @article{Amatore:2008a,
title = {Electrochemical monitoring of single cell secretion: Vesicular exocytosis and oxidative stress},
author = {C Amatore and S Arbault and M Guille and F Lema\^{i}tre},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-49049112285&doi=10.1021%2fcr068062g&partnerID=40&md5=ae6a20b01b9ae57f75d37389b0ebe3ec},
doi = {10.1021/cr068062g},
year = {2008},
date = {2008-01-01},
journal = {Chemical Reviews},
volume = {108},
number = {7},
pages = {2585--2621},
abstract = {Several important contributions of electroanalytical techniques over the past 20 years for investigating three major biological processes at the single cell level: vesicular exocytosis, oxidative stress, and nitric oxide metabolism in brain have been reported. It is evident that molecular electrochemistry at microelectrodes enhances the understanding of central processes of cellular biology including cellular metabolism either at a single cell stage or in living tissues. Since cells have highly variable metabolism even among single genetic lines, studies performed at the single cell level allow delineating precisely the extent and limits of these variabilities.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Several important contributions of electroanalytical techniques over the past 20 years for investigating three major biological processes at the single cell level: vesicular exocytosis, oxidative stress, and nitric oxide metabolism in brain have been reported. It is evident that molecular electrochemistry at microelectrodes enhances the understanding of central processes of cellular biology including cellular metabolism either at a single cell stage or in living tissues. Since cells have highly variable metabolism even among single genetic lines, studies performed at the single cell level allow delineating precisely the extent and limits of these variabilities. |
2007
|
Comparison of apex and bottom secretion efficiency at chromaffin cells as measured by amperometry Article de journal C Amatore; S Arbault; F Lemaître; Y Verchier Biophysical Chemistry, 127 (3), p. 165–171, 2007. @article{Amatore:2007a,
title = {Comparison of apex and bottom secretion efficiency at chromaffin cells as measured by amperometry},
author = {C Amatore and S Arbault and F Lema\^{i}tre and Y Verchier},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33947329500&doi=10.1016%2fj.bpc.2007.01.007&partnerID=40&md5=2cf451e422357961982f90bcbe7697e3},
doi = {10.1016/j.bpc.2007.01.007},
year = {2007},
date = {2007-01-01},
journal = {Biophysical Chemistry},
volume = {127},
number = {3},
pages = {165--171},
abstract = {In chromaffin cells, the exocytosis of neuromediators involves the fusion between a secretory vesicle and the cell membrane. Many techniques based on electrophysiology, electrochemistry and fluorescence microscopy allow the study of such a complex process at active zones of single immobilized cells. These techniques can provide an effective analysis either at the apex, either at the base of the cell adhering onto a substrate. For instance, patch-clamp (electrophysiology) and amperometry (electrochemistry) deal with detection at the exposed top of the cell, whereas evanescent field microscopy concerns mainly its bottom, i.e., the zone on which the cell rests onto the surface. However, in chromaffin cells, comparison between the two sets of methods remains to be established and whether apex fusion events are comparable or not to those observed at the base of the cell is an open question. In this work, we compare both active zones upon using the same measurement method, viz., by performing electrochemical detection at these both poles (top and bottom) of bovine chromaffin cells. This is performed upon using carbon fiber microelectrodes (apical analysis) and planar ITO transparent (basal analysis) electrodes, respectively. Our results indicate that the processes monitored at each pole differ though the same technique is used. © 2007 Elsevier B.V. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In chromaffin cells, the exocytosis of neuromediators involves the fusion between a secretory vesicle and the cell membrane. Many techniques based on electrophysiology, electrochemistry and fluorescence microscopy allow the study of such a complex process at active zones of single immobilized cells. These techniques can provide an effective analysis either at the apex, either at the base of the cell adhering onto a substrate. For instance, patch-clamp (electrophysiology) and amperometry (electrochemistry) deal with detection at the exposed top of the cell, whereas evanescent field microscopy concerns mainly its bottom, i.e., the zone on which the cell rests onto the surface. However, in chromaffin cells, comparison between the two sets of methods remains to be established and whether apex fusion events are comparable or not to those observed at the base of the cell is an open question. In this work, we compare both active zones upon using the same measurement method, viz., by performing electrochemical detection at these both poles (top and bottom) of bovine chromaffin cells. This is performed upon using carbon fiber microelectrodes (apical analysis) and planar ITO transparent (basal analysis) electrodes, respectively. Our results indicate that the processes monitored at each pole differ though the same technique is used. © 2007 Elsevier B.V. All rights reserved. |
Rate and mechanism of the Heck reactions of arylpalladium complexes ligated by a bidentate P,P ligand with an electron-rich alkene (isobutyl vinyl ether) Article de journal C Amatore; B Godin; A Jutand; F Lemaître Organometallics, 26 (7), p. 1757–1761, 2007. @article{Amatore:2007m,
title = {Rate and mechanism of the Heck reactions of arylpalladium complexes ligated by a bidentate P,P ligand with an electron-rich alkene (isobutyl vinyl ether)},
author = {C Amatore and B Godin and A Jutand and F Lema\^{i}tre},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34047269783&doi=10.1021%2fom0610849&partnerID=40&md5=2a491d504169e86693a654879673a004},
doi = {10.1021/om0610849},
year = {2007},
date = {2007-01-01},
journal = {Organometallics},
volume = {26},
number = {7},
pages = {1757--1761},
abstract = {Two main intermediate complexes, PhPd(OAc)(dppp) and PhPdI(dppp), are generated in palladium-catalyzed Heck reactions performed from Phi and an acetate salt used as a base, in DMF. Both complexes react with the electron-rich alkene isobutyl vinyl ether (CH2=CHOiBu) exclusively by an ionic mechanism, i.e., via the cationic complex [PhPd(dppp)(DMF)]+ formed by dissociation of AcO- or I- from the parent complexes, as already established for the reaction of PhPd(OAc)(dppp) with styrene and methyl acrylate and the reaction of PhPdI(dppp) with styrene. A mechanism is proposed which rationalizes the regioselectivity observed when reacting the electron-rich isobutylvinyl ether in palladium-catalyzed Heck reactions. © 2007 American Chemical Society.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Two main intermediate complexes, PhPd(OAc)(dppp) and PhPdI(dppp), are generated in palladium-catalyzed Heck reactions performed from Phi and an acetate salt used as a base, in DMF. Both complexes react with the electron-rich alkene isobutyl vinyl ether (CH2=CHOiBu) exclusively by an ionic mechanism, i.e., via the cationic complex [PhPd(dppp)(DMF)]+ formed by dissociation of AcO- or I- from the parent complexes, as already established for the reaction of PhPd(OAc)(dppp) with styrene and methyl acrylate and the reaction of PhPdI(dppp) with styrene. A mechanism is proposed which rationalizes the regioselectivity observed when reacting the electron-rich isobutylvinyl ether in palladium-catalyzed Heck reactions. © 2007 American Chemical Society. |
Rate and mechanism of the reaction of alkenes with aryl palladium complexes ligated by a bidentate P,P ligand in heck reactions Article de journal C Amatore; B Godin; A Jutand; F Lemaître Chemistry - A European Journal, 13 (7), p. 2002–2011, 2007. @article{Amatore:2007l,
title = {Rate and mechanism of the reaction of alkenes with aryl palladium complexes ligated by a bidentate P,P ligand in heck reactions},
author = {C Amatore and B Godin and A Jutand and F Lema\^{i}tre},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34047255523&doi=10.1002%2fchem.200600153&partnerID=40&md5=e35f1944755f6ed53bb8c914de847d02},
doi = {10.1002/chem.200600153},
year = {2007},
date = {2007-01-01},
journal = {Chemistry - A European Journal},
volume = {13},
number = {7},
pages = {2002--2011},
abstract = {The regioselectivity of the Heck reaction is supposed to be highly affected by the electronic properties of the alkene and the ionic or neutral character of the aryl palladium(II) complexes involved in the reaction with alkenes. In Heck reactions performed in dmf. [Pd(dppp)-(dppp(O))Ph]+ (dppp= 1,2-bis(diphenylphosphino)propane) is generated in the oxidative addition of Phi with [Pd0-(dppp)(OAc)] formed in situ from Pd(OAc): associated to two equivalents of dppp. [Pd(dppp)jdppp(O))Ph]+ is not very reactive with alkenes (styrene or methyl acrylate); however, it reacts with iodide ions (released in the catalytic reactions) to give [Pd(dppp)IPh) and with acetate ions (used as base) to give [Pd(dppp)(OAc)Ph]. [Pd(dppp)-(OAc)Ph] reacts with styrene and methyl acrylate exclusively by an ionic mechanism, that is. via the cationic complex [Pd(dppp)(dmf)Ph]+ formed by dissociation of the acetate ion. The reaction of [Pd(dppp)IPh] is more complex and substrate dependent. It reacts with styrene exclusively by the ionic mechanism via [Pd(dppp)-(dmf)Ph]+. [Pd(dppp)IPh] (neutral mechanism) and [Pd(dppp)(dmf)Ph]+ (ionic mechanism) react in parallel with methyl acrylate. [Pd(dppp)-(dmf)Ph]+ is more reactive than [Pd-(dppp)IPh) but is always generated at lower concentration. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The regioselectivity of the Heck reaction is supposed to be highly affected by the electronic properties of the alkene and the ionic or neutral character of the aryl palladium(II) complexes involved in the reaction with alkenes. In Heck reactions performed in dmf. [Pd(dppp)-(dppp(O))Ph]+ (dppp= 1,2-bis(diphenylphosphino)propane) is generated in the oxidative addition of Phi with [Pd0-(dppp)(OAc)] formed in situ from Pd(OAc): associated to two equivalents of dppp. [Pd(dppp)jdppp(O))Ph]+ is not very reactive with alkenes (styrene or methyl acrylate); however, it reacts with iodide ions (released in the catalytic reactions) to give [Pd(dppp)IPh) and with acetate ions (used as base) to give [Pd(dppp)(OAc)Ph]. [Pd(dppp)-(OAc)Ph] reacts with styrene and methyl acrylate exclusively by an ionic mechanism, that is. via the cationic complex [Pd(dppp)(dmf)Ph]+ formed by dissociation of the acetate ion. The reaction of [Pd(dppp)IPh] is more complex and substrate dependent. It reacts with styrene exclusively by the ionic mechanism via [Pd(dppp)-(dmf)Ph]+. [Pd(dppp)IPh] (neutral mechanism) and [Pd(dppp)(dmf)Ph]+ (ionic mechanism) react in parallel with methyl acrylate. [Pd(dppp)-(dmf)Ph]+ is more reactive than [Pd-(dppp)IPh) but is always generated at lower concentration. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA. |
Relationship between amperometric pre-spike feet and secretion granule composition in Chromaffin cells: An overview Article de journal C Amatore; S Arbault; I Bonifas; M Guille; F Lemaître; Y Verchier Biophysical Chemistry, 129 (2-3), p. 181–189, 2007. @article{Amatore:2007n,
title = {Relationship between amperometric pre-spike feet and secretion granule composition in Chromaffin cells: An overview},
author = {C Amatore and S Arbault and I Bonifas and M Guille and F Lema\^{i}tre and Y Verchier},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34547560678&doi=10.1016%2fj.bpc.2007.05.018&partnerID=40&md5=c92376d4195c4dfec6edfd9e5eb98173},
doi = {10.1016/j.bpc.2007.05.018},
year = {2007},
date = {2007-01-01},
journal = {Biophysical Chemistry},
volume = {129},
number = {2-3},
pages = {181--189},
abstract = {Amperometry is a simple and powerful technique to study exocytosis at the single cell level. By positioning and polarizing (at an appropriate potential at which the molecules released by the cell can be oxidized) a carbon fiber microelectrode at the top of the cell, each exocytotic event is detected as an amperometric spike. More particularly, a portion of these spikes has previously been shown to present a foot, i.e. a small pedestal of current that precedes the spike itself. Among the important number of works dealing with the monitoring of exocytosis by amperometry under different conditions, only a few studies focus on amperometric spikes with a foot. In this work, by coupling our previous and recent experiments on chromaffin cells (that release catecholamines after stimulation) with literature data, we bring more light on what an amperometric foot and particularly its features, represents. © 2007.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Amperometry is a simple and powerful technique to study exocytosis at the single cell level. By positioning and polarizing (at an appropriate potential at which the molecules released by the cell can be oxidized) a carbon fiber microelectrode at the top of the cell, each exocytotic event is detected as an amperometric spike. More particularly, a portion of these spikes has previously been shown to present a foot, i.e. a small pedestal of current that precedes the spike itself. Among the important number of works dealing with the monitoring of exocytosis by amperometry under different conditions, only a few studies focus on amperometric spikes with a foot. In this work, by coupling our previous and recent experiments on chromaffin cells (that release catecholamines after stimulation) with literature data, we bring more light on what an amperometric foot and particularly its features, represents. © 2007. |
The Nature and Efficiency of Neurotransmitter Exocytosis Also Depend on Physicochemical Parameters Article de journal Christian Amatore; Stephane Arbault; Manon Guille; Frederic Lemaitre Chemphyschem, 8 (11), p. 1597-1605, 2007, ISSN: 1439-4235. @article{RN21b,
title = {The Nature and Efficiency of Neurotransmitter Exocytosis Also Depend on Physicochemical Parameters},
author = {Christian Amatore and Stephane Arbault and Manon Guille and Frederic Lemaitre},
doi = {10.1002/cphc.200700225},
issn = {1439-4235},
year = {2007},
date = {2007-01-01},
journal = {Chemphyschem},
volume = {8},
number = {11},
pages = {1597-1605},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
Vesicular exocytosis under hypotonic conditions shows two distinct populations of dense core vesicles in bovine chromaffin cells Article de journal C Amatore; S Arbault; I Bonifas; F Lemaître; Y Verchier ChemPhysChem, 8 (4), p. 578–585, 2007. @article{Amatore:2007p,
title = {Vesicular exocytosis under hypotonic conditions shows two distinct populations of dense core vesicles in bovine chromaffin cells},
author = {C Amatore and S Arbault and I Bonifas and F Lema\^{i}tre and Y Verchier},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33947203763&doi=10.1002%2fcphc.200600607&partnerID=40&md5=b2b8413df28dc06b218792682443845e},
doi = {10.1002/cphc.200600607},
year = {2007},
date = {2007-01-01},
journal = {ChemPhysChem},
volume = {8},
number = {4},
pages = {578--585},
abstract = {Several previous reports have discussed the effects of external osmolarity on vesicular exocytotic processes. However, few of these studies considered hypotonic conditions on chromaffin cells. Herein, the exocytosis of catecholamines by chromaffin cells was investigated in a medium of low osmolarity (200 mOsm) by amperometry at carbon fiber microelectrodes. It is observed that the frequency of the exocytotic events is significantly higher under hypotonic conditions than under physiological conditions (315 mOsm). This further confirms that the swelling of the polyelectrolytic matrix (which follows ionic exchanges) contained in dense core vesicles is the energetic driving force of the exocytotic phenomenon, being favored by a lower osmolarity. The mean amount of catecholamines released during secretory events also increases importantly under the hypotonic condition. This may be rationalized by the coexistence of two distinct populations of dense core vesicles with a relative content ratio of 4.7. The larger content population is favored under hypotonic conditions but plays only a side role under isotonic conditions. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Several previous reports have discussed the effects of external osmolarity on vesicular exocytotic processes. However, few of these studies considered hypotonic conditions on chromaffin cells. Herein, the exocytosis of catecholamines by chromaffin cells was investigated in a medium of low osmolarity (200 mOsm) by amperometry at carbon fiber microelectrodes. It is observed that the frequency of the exocytotic events is significantly higher under hypotonic conditions than under physiological conditions (315 mOsm). This further confirms that the swelling of the polyelectrolytic matrix (which follows ionic exchanges) contained in dense core vesicles is the energetic driving force of the exocytotic phenomenon, being favored by a lower osmolarity. The mean amount of catecholamines released during secretory events also increases importantly under the hypotonic condition. This may be rationalized by the coexistence of two distinct populations of dense core vesicles with a relative content ratio of 4.7. The larger content population is favored under hypotonic conditions but plays only a side role under isotonic conditions. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA. |
2006
|
Coupling of electrochemistry and fluorescence microscopy at indium tin oxide microelectrodes for the analysis of single exocytotic events Article de journal C Amatore; S Arbault; Y Chen; C Crozatier; F Lemaître; Y Verchier Angewandte Chemie - International Edition, 45 (24), p. 4000–4003, 2006. @article{Amatore:2006,
title = {Coupling of electrochemistry and fluorescence microscopy at indium tin oxide microelectrodes for the analysis of single exocytotic events},
author = {C Amatore and S Arbault and Y Chen and C Crozatier and F Lema\^{i}tre and Y Verchier},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33746309503&doi=10.1002%2fanie.200600510&partnerID=40&md5=6db1449bc0c22c777137713c0df11dc1},
doi = {10.1002/anie.200600510},
year = {2006},
date = {2006-01-01},
journal = {Angewandte Chemie - International Edition},
volume = {45},
number = {24},
pages = {4000--4003},
abstract = {(Figure Presented) One-off analysis: Quantitative, kinetic, and spatial monitoring of single biological events involving vesicular secretion such as exocytosis may be achieved by combining electrochemistry with fluorescence microscopy at indium tin oxide (ITO) transparent microelectrodes. This method paves the way for real-time tracking of the intracellular fate of vesicles while monitoring precisely their dynamics of fusion. © 2006 Wiley-VCH Verlag GmbH & Co. KGaA.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
(Figure Presented) One-off analysis: Quantitative, kinetic, and spatial monitoring of single biological events involving vesicular secretion such as exocytosis may be achieved by combining electrochemistry with fluorescence microscopy at indium tin oxide (ITO) transparent microelectrodes. This method paves the way for real-time tracking of the intracellular fate of vesicles while monitoring precisely their dynamics of fusion. © 2006 Wiley-VCH Verlag GmbH & Co. KGaA. |
Regulation of exocytosis in chromaffin cells by Trans-insertion of lysophosphatidylcholine and arachidonic acid into the outer leaflet of the cell membrane Article de journal C Amatore; S Arbault; Y Bouret; M Guille; F Lemaître; Y Verchier ChemBioChem, 7 (12), p. 1998–2003, 2006. @article{Amatore:2006i,
title = {Regulation of exocytosis in chromaffin cells by Trans-insertion of lysophosphatidylcholine and arachidonic acid into the outer leaflet of the cell membrane},
author = {C Amatore and S Arbault and Y Bouret and M Guille and F Lema\^{i}tre and Y Verchier},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33845431788&doi=10.1002%2fcbic.200600194&partnerID=40&md5=ee09aa44f07bb791da49cab4b5ce936a},
doi = {10.1002/cbic.200600194},
year = {2006},
date = {2006-01-01},
journal = {ChemBioChem},
volume = {7},
number = {12},
pages = {1998--2003},
abstract = {Vesicular exocytosis is an important complex process in the communication between cells in organisms. It controls the release of chemical and biochemical messengers stored in an emitting cell. In this report, exocytosis is studied amperometrically (at carbon fiber ultramicroelectrodes) at adrenal chromaffin cells, which release catecholamines after appropriate stimulation, while testing the effects due to trans-insertion of two exogenous compounds (lysophosphatidylcholine (LPC) and arachidonic acid (AA)) on the kinetics of exocytotic events. Amperometric analyses showed that, under the present conditions (short incubation times and micromolar LPC or AA solutions), LPC favors catecholamine release (rate, event frequency, charge released) while AA disfavors the exocytotic processes. The observed kinetic features are rationalized quantitatively by considering a stalk model, for the fusion pore formation, and the physical constraints applied to the cell membrane by the presence of small fractions of LPC and AA diluted in its external leaflet (trans-insertion). We also observed that the detected amount of neurotransmitters in the presence of LPC was larger than under control conditions, while the opposite trend is observed with AA. © 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Vesicular exocytosis is an important complex process in the communication between cells in organisms. It controls the release of chemical and biochemical messengers stored in an emitting cell. In this report, exocytosis is studied amperometrically (at carbon fiber ultramicroelectrodes) at adrenal chromaffin cells, which release catecholamines after appropriate stimulation, while testing the effects due to trans-insertion of two exogenous compounds (lysophosphatidylcholine (LPC) and arachidonic acid (AA)) on the kinetics of exocytotic events. Amperometric analyses showed that, under the present conditions (short incubation times and micromolar LPC or AA solutions), LPC favors catecholamine release (rate, event frequency, charge released) while AA disfavors the exocytotic processes. The observed kinetic features are rationalized quantitatively by considering a stalk model, for the fusion pore formation, and the physical constraints applied to the cell membrane by the presence of small fractions of LPC and AA diluted in its external leaflet (trans-insertion). We also observed that the detected amount of neurotransmitters in the presence of LPC was larger than under control conditions, while the opposite trend is observed with AA. © 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. |
2004
|
Formation of anionic palladium(0) complexes ligated by the trifluoroacetate ion and their reactivity in oxidative addition Article de journal C Amatore; A Jutand; F Lemaître; J L Ricard; S Kozuch; S Shaik Journal of Organometallic Chemistry, 689 (23), p. 3728–3734, 2004. @article{Amatore:2004a,
title = {Formation of anionic palladium(0) complexes ligated by the trifluoroacetate ion and their reactivity in oxidative addition},
author = {C Amatore and A Jutand and F Lema\^{i}tre and J L Ricard and S Kozuch and S Shaik},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-18844439358&doi=10.1016%2fj.jorganchem.2004.05.012&partnerID=40&md5=959081b6968f83e014ddf0cca8a963ce},
doi = {10.1016/j.jorganchem.2004.05.012},
year = {2004},
date = {2004-01-01},
journal = {Journal of Organometallic Chemistry},
volume = {689},
number = {23},
pages = {3728--3734},
abstract = {As established previously for Pd(OAc)2, Pd0 complexes are formed in situ from Pd(OCOCF3)2 and n equiv. triarylphosphines (4-Z-C6H4)3P (Z = CF 3, F, Cl, H, CH3; n ≥ 3). The phosphines are the intramolecular reducing agents and are oxidized to triarylphosphine oxides. The generated Pd0 complexes are anionic species ligated by the trifluoroacetate anion: Pd0(PAr3)n(OCOCF 3)- (n = 2 or 3). Pd0(PAr3) 2(OCOCF3)- is the reactive species involved in the oxidative addition to PhI. This leads to trans-PhPd(OCOCF 3)(PPh3)2, involved in equilibrium with the cationic complex trans-[PhPd(PPh3)2(DMF)]+, instead of the expected trans-PhPdI(PPh3)2 complex. The existence of anionic Pd0 complexes ligated by the acetate or trifluoroacetate ions delivered by the precursors Pd(OAc)2 or Pd(OCOCF3)2, respectively, as well as their comparative reactivity in oxidative additions are consistent with theoretical DFT calculations. © 2004 Elsevier B.V. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
As established previously for Pd(OAc)2, Pd0 complexes are formed in situ from Pd(OCOCF3)2 and n equiv. triarylphosphines (4-Z-C6H4)3P (Z = CF 3, F, Cl, H, CH3; n ≥ 3). The phosphines are the intramolecular reducing agents and are oxidized to triarylphosphine oxides. The generated Pd0 complexes are anionic species ligated by the trifluoroacetate anion: Pd0(PAr3)n(OCOCF 3)- (n = 2 or 3). Pd0(PAr3) 2(OCOCF3)- is the reactive species involved in the oxidative addition to PhI. This leads to trans-PhPd(OCOCF 3)(PPh3)2, involved in equilibrium with the cationic complex trans-[PhPd(PPh3)2(DMF)]+, instead of the expected trans-PhPdI(PPh3)2 complex. The existence of anionic Pd0 complexes ligated by the acetate or trifluoroacetate ions delivered by the precursors Pd(OAc)2 or Pd(OCOCF3)2, respectively, as well as their comparative reactivity in oxidative additions are consistent with theoretical DFT calculations. © 2004 Elsevier B.V. All rights reserved. |
