| 1. |
- Schael, S., et al.
(författare)
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Electroweak measurements in electron positron collisions at W-boson-pair energies at LEP
- 2013
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Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 532:4, s. 119-244
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Forskningsöversikt (refereegranskat)abstract
- Electroweak measurements performed with data taken at the electron positron collider LEP at CERN from 1995 to 2000 are reported. The combined data set considered in this report corresponds to a total luminosity of about 3 fb(-1) collected by the four LEP experiments ALEPH, DELPHI, 13 and OPAL, at centre-of-mass energies ranging from 130 GeV to 209 GeV. Combining the published results of the four LEP experiments, the measurements include total and differential cross-sections in photon-pair, fermion-pair and four-fermion production, the latter resulting from both double-resonant WW and ZZ production as well as singly resonant production. Total and differential cross-sections are measured precisely, providing a stringent test of the Standard Model at centre-of-mass energies never explored before in electron positron collisions. Final-state interaction effects in four-fermion production, such as those arising from colour reconnection and Bose Einstein correlations between the two W decay systems arising in WW production, are searched for and upper limits on the strength of possible effects are obtained. The data are used to determine fundamental properties of the W boson and the electroweak theory. Among others, the mass and width of the W boson, m(w) and Gamma(w), the branching fraction of W decays to hadrons, B(W -> had), and the trilinear gauge-boson self-couplings g(1)(Z), K-gamma and lambda(gamma), are determined to be: m(w) = 80.376 +/- 0.033 GeV Gamma(w) = 2.195 +/- 0.083 GeV B(W -> had) = 67.41 +/- 0.27% g(1)(Z) = 0.984(-0.020)(+0.018) K-gamma - 0.982 +/- 0.042 lambda(gamma) = 0.022 +/- 0.019. (C) 2013 Elsevier B.V. All rights reserved.
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| 2. |
- Schael, S, et al.
(författare)
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Precision electroweak measurements on the Z resonance
- 2006
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Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
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Forskningsöversikt (refereegranskat)abstract
- We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLID experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, m(Z) and Gamma(Z), and its couplings to fermions, for example the p parameter and the effective electroweak mixing angle for leptons, are precisely measured: m(Z) = 91.1875 +/- 0.0021 GeV, Gamma(Z) = 2.4952 +/- 0.0023 GeV, rho(l) = 1.0050 +/- 0.0010, sin(2)theta(eff)(lept) = 0.23153 +/- 0.00016. The number of light neutrino species is determined to be 2.9840 +/- 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, m(t) = 173(+10)(+13) GeV, and the mass of the W boson, m(W) = 80.363 +/- 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of m(t) and m(W), the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level. (c) 2006 Elsevier B.V. All rights reserved.
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| 3. |
- Droguerre, Marine, et al.
(författare)
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A New Tool for In Vivo Study of Astrocyte Connexin 43 in Brain.
- 2019
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- Astrocytes are glial cells organized in dynamic and structured networks in the brain. These plastic networks, involving key proteins such as connexin 43 (Cx43), are engaged in fine neuronal tuning and have recently been considered as emerging therapeutic targets in central nervous system disorders. We developed and validated a new application of the manganese-enhanced magnetic resonance imaging (MEMRI) technique allowing in vivo investigations of astrocyte-neuron interactions through quantification of brain Cx43 functional activity. The proof of concept has been achieved by quantification of MEMRI signals in brain after either local astrocyte-specific Cx43 knockdown with shRNA or systemic administration of Cx43 blockers. Unilateral hippocampal Cx43 genetical silencing was associated with an ipsilateral local increase of MEMRI signal. Furthermore, Cx43 blockers also enhanced MEMRI signal responses in hippocampus. Altogether, these data reveal the MEMRI technique as a tool for quantitative imaging of in vivo Cx43-dependent function in astrocytes under physiological and pathological conditions.
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| 4. |
- Droguerre, Marine, et al.
(författare)
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Efficacy of THN201, a Combination of Donepezil and Mefloquine, to Reverse Neurocognitive Deficits in Alzheimer's Disease.
- 2020
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Ingår i: Frontiers in Neuroscience. - : Frontiers Media SA. - 1662-4548 .- 1662-453X. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- Donepezil (DPZ) is an acetylcholinesterase inhibitor used in Alzheimer's disease to restore cognitive functions but is endowed with limited efficacy. Recent studies pointed out the implication of astroglial networks in cognitive processes, notably via astrocyte connexins (Cxs), proteins involved in gap junction intercellular communications. Hence, we investigated the impact on cognition of pharmacological or genetic modulations of those astrocyte Cxs during DPZ challenge in two rodent models of Alzheimer's disease-like memory deficits. We demonstrated that the Cx modulator mefloquine (MEF) significantly enhanced the procognitive effect of DPZ in both models. In parallel, we determined that MEF potentiated DPZ-induced release of acetylcholine in hippocampus. Finally, local genetic silencing of astrocyte Cxs in the hippocampus was also found to enhance the procognitive effect of DPZ, pointing out the importance of Cx-dependent astrocyte networks in memory processes.
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| 5. |
- Portal, Benjamin, et al.
(författare)
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Genetic and pharmacological inactivation of astroglial connexin 43 differentially influences the acute response of antidepressant and anxiolytic drugs.
- 2020
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Ingår i: Acta Physiologica. - : Wiley. - 1748-1708 .- 1748-1716. ; 229:1
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Tidskriftsartikel (refereegranskat)abstract
- AIM: Astroglial connexins (Cxs) 30 and 43 are engaged in gap junction and hemichannel activities. Evidence suggests that these functional entities contribute to regulating neurotransmission, thereby influencing brain functions. In particular, preclinical and clinical findings highlight a role of Cx43 in animal models of depression. However, the role of these proteins in response to currently available psychotropic drugs is still unknown.METHODS: To investigate this, we evaluated the behavioural effects of the genetic and pharmacological inactivation of Cx43 on the antidepressant- and anxiolytic-like activities of the selective serotonin reuptake inhibitor fluoxetine and the benzodiazepine diazepam, respectively.RESULTS: A single administration of fluoxetine (18 mg/kg; i.p.) produced a higher increase in hippocampal extracellular serotonin levels, and a greater antidepressant-like effect in the tail suspension test in Cx43 knock-down (KD) mice bred on a C57BL/6 background compared to their wild-type littermates. Similarly, in outbred Swiss wild-type mice, the intra-hippocampal injection of a shRNA-Cx43 or the acute systemic injection of the Cxs inhibitor carbenoxolone (CBX: 10 mg/kg; i.p.) potentiated the antidepressant-like effects of fluoxetine. Evaluating the effects of such strategies on diazepam (0.5 mg/kg; i.p.), the results indicate that Cx43 KD mice or wild-types injected with a shRNA-Cx43 in the amygdala, but not in the hippocampus, attenuated the anxiolytic-like effects of this benzodiazepine in the elevated plus maze. The chronic systemic administration of CBX mimicked the latter observations.CONCLUSION: Collectively, these data pave the way to the development of potentiating strategies in the field of psychiatry based on the modulation of astroglial Cx43.
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| 6. |
- Quesseveur, Gaël, et al.
(författare)
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Attenuated Levels of Hippocampal Connexin 43 and its Phosphorylation Correlate with Antidepressant- and Anxiolytic-Like Activities in Mice.
- 2015
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Ingår i: Frontiers in Cellular Neuroscience. - : Frontiers Media SA. - 1662-5102. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Clinical and preclinical studies have implicated glial anomalies in major depression. Conversely, evidence suggests that the activity of antidepressant drugs is based, at least in part, on their ability to stimulate density and/or activity of astrocytes, a major glial cell population. Despite this recent evidence, little is known about the mechanism(s) by which astrocytes regulate emotionality. Glial cells communicate with each other through gap junction channels (GJCs), while they can also directly interact with neurons by releasing gliotransmitters in the extracellular compartment via an hemichannels (HCs)-dependent process. Both GJCs and HCs are formed by two main protein subunits: connexins (Cx) 30 and 43 (Cx30 and Cx43). Here we investigate the role of hippocampal Cx43 in the regulation of depression-like symptoms using genetic and pharmacological approaches. The first aim of this study was to evaluate the impact of the constitutive knock-down of Cx43 on a set of behaviors known to be affected in depression. Conversely, the expression of Cx43 was assessed in the hippocampus of mice subjected to prolonged corticosterone (CORT) exposure, given either alone or in combination with an antidepressant drug, the selective serotonin reuptake inhibitor fluoxetine. Our results indicate that the constitutive deficiency of Cx43 resulted in the expression of some characteristic hallmarks of antidepressant-/anxiolytic-like behavioral activities along with an improvement of cognitive performances. Moreover, in a new cohort of wild-type mice, we showed that CORT exposure elicited anxiety and depression-like abnormalities that were reversed by chronic administration of fluoxetine. Remarkably, CORT also increased hippocampal amounts of phosphorylated form of Cx43 whereas fluoxetine treatment normalized this parameter. From these results, we envision that antidepressant drugs may exert their therapeutic activity by decreasing the expression and/or activity of Cx43 resulting from a lower level of phosphorylation in the hippocampus.
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