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71.
Libouban H Blouin S Moreau MF Baslé MF Audran M Chappard D 《Micron (Oxford, England : 1993)》2008,39(7):998-1007
Dual energy X-ray absorptiometry (DXA), histomorphometry and X-ray microtomography (microCT) were used to assess effects of risedronate and testosterone in a combined rat model of orchidectomy (ORX) and local paralysis induced by botulinum neurotoxin (BTX). Four groups of mature rats were studied for 1 month: SHAM operated; ORX and right hindlimb immobilization (BTX); ORX+BTX+risedronate or testosterone. Changes in bone and body composition were measured by DXA (BMC, lean and fat mass), histomorphometry (BV/TV(2D), Tb.Th and microarchitectural parameters) and microCT (BV/TV(3D), SMI and cortical parameters). ORX and BTX had additive effects on bone loss since differences were maximized on the immobilized bone. The decrease in BMC on the tibial metaphysis reached -33.6% vs. -11.3% in the non-immobilized limb. BV/TV and Tb.N decreased and Tb.Sp increased in both hindlimbs whereas Tb.Th was significantly lower only in the immobilized limb. Decrease of tibial cortical area and thickness was greater in the immobilized limb. Risedronate prevented BMC, BV/TV and architecture loss but not reduction in Tb.Th. Cortical bone was preserved only in the non-immobilized limb. Testosterone was unable to prevent trabecular and cortical bone loss, but it prevents loss of whole body lean mass. In conclusion, ORX and BTX resulted in additive effects on bone loss. Risedronate had protective effects on trabecular bone loss but was less effective on cortical bone. 相似文献
72.
Léo Birbaum Dr. Laurent Gillard Prof. Hélène Gérard Prof. Hassan Oulyadi Dr. Guillaume Vincent Prof. Xavier Moreau Dr. Michael De Paolis Prof. Isabelle Chataigner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(60):13688-13693
3-Nitroindoles are easily reacted with highly substituted γ-allenoates in the presence of a commercially available phosphine catalyst. For instance, allenoates derived from biomolecules such as amino and deoxycholic acids are combined for the first time with 3-nitroindole. The corresponding dearomatized (3+2) tricyclic cycloadducts are obtained as α-regioisomers exclusively. DFT computations shed light on this multi-step reaction mechanism and on the selectivities observed in the sequence. 相似文献
73.
74.
P. Etienne P. Coudray Y. Moreau J. Porque 《Journal of Sol-Gel Science and Technology》1998,13(1-3):523-527
The development and characterization of channel waveguides using wet-process, low temperature sol-gel chemistry is described. Two structures have been developed. The first one is a one-layer structure, composed of a sol-gel solution which is a mixture of photopolymerizable organosilicate and organozirconate precursors. The other is a multilayer structure with a buffer under the guide and a protective coating. The layers are deposited by the dipping technique. The devices are obtained by UV light exposure of the coating through a predefined mask (channel waveguides). The refractive index increase is sufficient enough to allow the use of waveguides in the 1.55 m telecommunication window.These waveguides are thick enough to reduce the coupling losses with an optical fiber below 0.5 dB. Also, because of our sandwich structure, the propagation losses are less than 0.1 dB. 相似文献
75.
L. Davoust R. Moreau M. D. Cowley P. A. Tanguy F. Bertrand 《Journal of Crystal Growth》1997,180(3-4):422-432
We present analytical and numerical models of magnetohydrodynamic(MHD) buoyancy-driven flow within the liquid pool of a horizontal Bridgman crystal growth furnace, under the influence of a uniform vertical magnetic field B0. A horizontal differentially heated cylinder, whose aspect ratio (radius to length) is small enough for a fully developed regime to be established in the central core, is considered. With Hartmann layers remaining electrically inactive, a modified Rayleigh number RaG, which is the ration of the ordinary Rayleigh number to the square of the Hartmann number, is found to control the MHD reorganisation of the flow. This modified Rayleigh number is a measure of the importance of thermal convection relative to diffusion if velocity is estimated from the balance between the torques of buoyancy and the Laplace force. When RaG is much smaller than unity (quasi-diffusive regime), an analytical modelling of the flow, based on a power series of RaG, demonstrates that this balance requires secondary vortices within vertical mid-planes of the cylinder, both within the core flow and near the end walls. A 3-D numerical calculation of the flow provides evidence of the transition from a convective MHD flow (when RaG is still of the order of unity) to the quasi-diffusive flow, analytically studied. Indeed, this transition takes the form of a rather complex 3-D MHD organisation of the flow which is due to the nonuniformity of the axial temperature gradient along the cylinder. 相似文献
76.
Heme degradation by heme oxygenase (HO) enzymes is important in maintaining iron homeostasis and prevention of oxidative stress, etc. In response to mechanistic uncertainties, we performed quantum mechanical/molecular mechanical investigations of the heme hydroxylation by HO, in the native route and with the oxygen surrogate donor H2O2. It is demonstrated that H2O2 cannot be deprotonated to yield Fe(III)OOH, and hence the surrogate reaction starts from the FeHOOH complex. The calculations show that, when starting from either Fe(III)OOH or Fe(III)HOOH, the fully concerted mechanism involving O-O bond breakage and O-C(meso) bond formation is highly disfavored. The low-energy mechanism involves a nonsynchronous, effectively concerted pathway, in which the active species undergoes first O-O bond homolysis followed by a barrier-free (small with Fe(III)HOOH) hydroxyl radical attack on the meso position of the porphyrin. During the reaction of Fe(III)HOOH, formation of the Por+*FeIV=O species, compound I, competes with heme hydroxylation, thereby reducing the efficiency of the surrogate route. All these conclusions are in accord with experimental findings (Chu, G. C.; Katakura, K.; Zhang, X.; Yoshida, T.; Ikeda-Saito, M. J. Biol. Chem. 1999, 274, 21319). The study highlights the role of the water cluster in the distal pocket in creating "function" for the enzyme; this cluster affects the O-O cleavage and the O-Cmeso formation, but more so it is responsible for the orientation of the hydroxyl radical and for the observed alpha-meso regioselectivity of hydroxylation (Ortiz de Montellano, P. R. Acc. Chem. Res. 1998, 31, 543). Differences/similarities with P450 and HRP are discussed. 相似文献
77.
Guanqi Wang Dr. Yohann Moreau Dr. Florian Berthiol Dr. Christian Philouze Dr. Olivier Jarjayes Prof. Fabrice Thomas 《欧洲无机化学杂志》2023,26(15):e202300223
The copper and nickel complexes of two tetradentate ligands derived from bis(aminophenol) and bis(phenol) architectures connected by an oxamate linker were isolated. Depending on the metal and ligand, the complex is isolated with either an intact (deprotonated) ligand ( 12− ), one-electron oxidized ligand ( 2− ) or quinone form ( 3 ). Surprisingly, the Mannich base is easier to oxidize than the amidophenol derivatives. The complexes were characterized by X-ray diffraction, cyclic voltammetry, UV-Vis-NIR and EPR spectroscopies. Complex 1 shows two reversible oxidation waves assigned to the successive iminosemiquinone/aminophenolate redox systems. Complex 2− shows an intense NIR feature, as well as an EPR signal at giso=2.043, consistent with a metallic contribution to the main ligand radical SOMO. Complex 3 shows the typical feature of an isolated Cu(II) complex. Spectro-electrochemistry coupled to DFT calculations demonstrate a ligand-centered oxidative redox chemistry for all the complexes. 相似文献
78.
Patrick Cancouët Elodie Daudet Grard Hlary Michel Moreau Georges Sauvet 《Journal of polymer science. Part A, Polymer chemistry》2000,38(5):826-836
Poly(hydrogenmethylsiloxane‐co‐dimethylsiloxane)s of various compositions have been prepared by cationic ring‐opening polymerization of octamethylcyclotetrasiloxane (D4) and 1,3,5,7‐tetramethylcyclotetrasiloxane (D) in the presence of hexamethyldisiloxane as end‐blocker or by rearrangement of poly(hydrogenmethylsiloxane) in the presence of D4. These copolymers were examined by high resolution 1H NMR (500.13 MHz) and 29Si NMR (99.37 MHz) spectroscopies. Triad effects were observed by 1H and up to heptad effects by 29Si NMR. The chemical shifts were assigned for these stereosequences. The intensities of the triad signals were used to calculate the quantitative parameters describing the microstructure of the copolymer chains: number‐average block length (L̄) and persistence ratio (η). The values of these parameters for copolymers prepared in various experimental conditions show that the time necessary for redistribution reactions (backbiting) is much larger than the time required to establish the equilibrium between linear polymer and cyclic oligomers. However, redistribution is fast enough to prevent the formation of block copolymers even in the case of the rearrangement of poly(hydrogenmethylsiloxane) in the presence of D4. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 826–836, 2000 相似文献
79.
Bernadette Charleux Michel Moreau Jean-Pierre Vairon Savvas Hadjikyriacou Rudolf Faust 《Macromolecular Symposia》1998,132(1):25-35
The use of non-homopolymerizable monomers such as 1,1-diphenylethylene (DPE) in the synthesis of functional polymers and block copolymers by cationic polymerization has been recently reported. The most important parameters in this process, the kinetics and extent of ionization and capping as well as the stability of the cation, were investigated by studying the reaction with TiCl4 of 1-methoxy-1,1-diphenyl-3,3,5,5-tetramethylhexane, a model for DPE-capped polyisobutene chain-end. This study was performed using 1H NMR and the high-purity stopped-flow device coupled with UV-visible spectroscopy. 相似文献
80.
Rmi Martinent Salman Tawffik Javier Lpez-Andarias Dimitri Moreau Quentin Laurent Stefan Matile 《Chemical science》2021,12(41):13922
The cytosolic delivery of various substrates in 3D multicellular spheroids by thiol-mediated uptake is reported. This is important because most orthodox systems, including polycationic cell-penetrating peptides, fail to deliver efficiently into deep tissue. The grand principles of supramolecular chemistry, that is the pH dependence of dynamic covalent disulfide exchange with known thiols on the transferrin receptor, are proposed to account for transcytosis into deep tissue, while the known but elusive exchange cascades along the same or other partners assure cytosolic delivery in kinetic competition. For quantitative detection in the cytosol, the 2D chloroalkane penetration assay (CAPA) is translated to 3D deep tissue. The targeted delivery of quantum dots, otherwise already troublesome in 2D culture, and the controlled release of mechanophores are realized to exemplify the power of thiol-mediated uptake into spheroids. As transporters, dithiolane quartets on streptavidin templates are introduced as modular motifs. Built from two amino acids only, the varied stereochemistry and peptide sequence are shown to cover maximal functional space with minimal structural change, i.e., constitutional isomers. Reviving a classic in peptide chemistry, this templated assembly of β quartets promises to expand streptavidin biotechnology in new directions, while the discovery of general cytosolic delivery in deep tissue as an intrinsic advantage further enhances the significance and usefulness of thiol-mediated uptake.Cytosolic delivery in multicellular 3D spheroids is shown to be an intrinsic advantage of thiol-mediated uptake, which is compatible with proteins and QDs, achieving targeting and controlled release. 相似文献