Identification of differential pattern of protein expression in canine osteoarthritis serum after anterior cruciate ligament transection: a proteomic analysis

Osteoarthritis (OA) management remains a great challenge and there is considerable effort to understand its pathophysiology and to identify new therapeutic targets and biomarkers. Canine OA surgically induced by the transection of the anterior cruciate ligament (ACLT) is a widely used and relevant model. This study reports a proteome mapping of dog serum and an analysis of the differentially expressed proteins between before and after ACLT. In the first part of the study, 261 picked protein spots were identified from preparative 2D gels and 71 different proteins were identified among the 261 spots present on the reference map. Canine serum proteome mapping reveals the presence of proteins of interest, such as fetuin B, complement C3 and C1s and pregnancy zone protein. The comparison between serum from dogs before and after ACLT reveals the differential expression of several proteins that could play a key role in the pathogenesis of OA. A number of proteins, such as fetuin B and complement C3, were increased in dog OA serum whereas others, such as hyaluronan binding protein 2, inter-alpha-trypsin inhibitor H4 (ITIH4), complement C1s and C4 and haptoglobin were decreased. Some of these proteins could be candidate biomarkers for diagnosis, prognosis and treatment evaluation. The results of the study also reinforced the similarities between dog experimental OA and human cases of OA.

Dye-Sensitized Nanostructured Crystalline Mesoporous Tin-doped Indium Oxide Films with Tunable Thickness for Photoelectrochemical Applications

A simple route towards nanostructured mesoporous Indium-Tin Oxide (templated nano-ITO) electrodes exhibiting both high conductivities and optimized bicontinuous pore-solid network is reported. The ITO films are first produced as an X-ray-amorphous, high surface area material, by adapting recently established template-directed sol-gel methods using Sn(IV) and In(III) salts. Carefully controlled temperature/atmosphere treatments convert the as-synthesized ITO films into nano-crystalline coatings with the cubic bixbyite structure. Specially, a multi-layered synthesis was successfully undertaken for tuning the film thickness. In order to evaluate the performances of templated nano-ITO as an electrode substrate for photoelectrochemical applications, photoelectrodes were prepared by covalent grafting of a redox-active dye, the complex [Ru(bpy)₂(4,4'-(CH₂PO₃H₂)₂-bpy)]Cl₂1 (bpy=bipyridine). Surface coverage was shown to increase with the film thickness, from 0.7 × 10^-9 mol.cm^-2 (one layer, 45 nm) to 3.5 × 10^-9 mol.cm^-2 (ten layers, 470 nm), the latter value being ~ 100 times larger than that for commercially available planar ITO. In the presence of an electron mediator, photocurrents up to 50 μA.cm^-2 have been measured under visible light irradiation, demonstrating the potential of this new templated nano-ITO preparation for the construction of efficient photoelectrochemical devices.

Subchondral bone and osteoarthritis: biological and cellular aspects

The subchondral bone is involved in the pathophysiology of osteoarthritis (OA), both by biochemical and mechanical pathways. Overloaded OA subchondral bone osteoblasts express a pro-angiogenic and pro-inflammatory phenotype which contributes to explain the structural changes (sclerosis and bone marrow lesion) visible in OA subchondral bone. Further, microfractures and conjonctivo-vascular structures constitute exchange routes between bone and the overlying cartilage for mediators produced by osteoblasts. This narrative review describes these physiopathological mechanisms and identifies possible therapeutic targets for pharmacological modalities.

Structure of arabinogalactan-protein from Acacia gum: from porous ellipsoids to supramolecular architectures

The structure of the arabinogalactan-protein (AGP) fraction of the gum exudate of Acacia senegal (gum Arabic) isolated from hydrophobic interaction chromatography was investigated using HPSEC-MALLS, small angle neutron scattering and TEM observations. Literature reported that the AGP structure of gum Arabic adopts a very compact conformation in solution due to the attachment of short arabinoside side chains and much larger blocks of carbohydrate to the polypeptidic backbone. The present study revealed that AGP in solution had a weight average molecular weight Mw of 1.86×10(6) g mol(-1) and a radius of gyration Rg of 30 nm. In addition, two exponent values were identified in the Rg, [η], Rh and ρ vs. Mw relationships highlighting two types of conformations depending on the molecular weight range considered: a low molar mass population with long-chain branching and a compact conformation and a high molar mass population with short-chain branching and an elongated conformation. AGP would behave in solution as a branched or hyper-branched polymer with conformations ranging from globular to elongated shape depending on the size of the carbohydrate branches. Small angle scattering form factor revealed an elongated average conformation corresponding to a triaxial ellipsoid while inverse Fourier transform of the scattering form factor gave a maximum dimension for AGP of 64 nm. Transmission electron microscopy highlighted the existence of two types of flat objects with thicknesses below 3-5 nm, single particles with a more or less anisotropic spheroidal shape and aggregated structures with a more elongated shape. A remarkable feature of all particle morphologies was the presence of an outer structure combined to an inner more or less porous network of interspersed chains or interacting structural blocks, as previously found for the arabinogalactan (AG) main molecular fraction of Acacia gum. However, clear differences were observed in the density and morphology of the inner porous network, probably highlighting differences in the degree of branching. The existence of assembled AG as part of the AGP family was confirmed using TEM micrographs at high resolution. Fused AGP dimers, trimers, tetramers and multimers were also identified. These molecular assemblies questioned about the nature of interactions involved.

Molecular Structure Of Metal Alkoxide Precursors

Oxo-alkoxides and allied derivatives are the organic counter part of polyanions and polycations. Most of them do not lead to further polymerization and are therefore dead endswhich are grnerally not directly involved in the formation of macromolecular oxide networks. However their well defined structure make them good models for the basic understanding of the first steps of hydrolysis- condensation reactions. The structural characterization of a new metal oxo species Ce6(μ3-O)4(μ3-OH)4(acac)12 obtained via the hydrolysis of acetylacetone modified cerium isopropoxide is presented. Possible mechanisms of formation of this compound as well as for some other titanium Ti6(μ2-O)2(μ3-O)2(μ2-OAc)4(μ2-OPri)6(OPri)6 and niobium Nb8O10(OEt)20 based oxo-alkoxides will be discussed.

The Gel Route to TiO2 Photoanodes

Cr3+ and Al3+ doped TiO2 can be easily made via the sol-gel process. Mixing the metal-organic solutions give rise to a random dispersion of the doping ions into the TiO2 network. Amorphous and crystalline phases have been characterized all the way from the gel to the crystalline products by thermal analysis, X-ray diffraction, vibrational spectroscopy and E.S.R. Organic groups appear to be involved in the formation of the gel network and could lead to a better control of the morphology of the xerogel. A thermal stabilization of the anatase phase, up to 900°C, is observed when Cr3+ is introduced as a dopant. This would lead to the preparation of anatase TiO2 photoanodes.

Synthesis and Characterization of Vanadium Oxide Gels from Alkoxy-Vanadate Precursors

Vanadium oxide gels are synthesized through vanadium oxo-alkoxide hydrolysis condensation processes. Different precursors and hydrolysis conditions lead to different sorts of gels. V0(0Amt)3 hydrolyzed with a large excess of water results in red jammy gels with a layered structure. They exhibit electronic and ionic behavior comparable to vanadium pentoxide gels from inorganic precursors. Hydrolysis of VO(OPrn)3 in an alcoholic medium, leads to orange transparent monolithic gels. They have a highly branched polymeric structure. Controlled hydrolysis of vanadium oxo-alkoxide precursors has the further advantage of giving good adherent thin films.

Hydrolysis-Condensation of Alkyltin-Trialkoxides

BuSn(OPri)3 and BuSn(OAmt)3 have been synthesized according to a literature procedure. Their hydrolysis have been studied by 119Sn and 1H NMR spectroscopy. The former precursor yields only a closo-type oxo-hydroxo cation of formula [(BuSn)12O14(OH)6]2+. Investigation of the hydrolysis-condensation products of BuSn(OAmt)3 reveals expanded coordinenceabout the tin atoms from 4 to 5 and 6 when H2O/Sn>l. For butyltin tri-tert-amyloxide, condensation also promotes the formation of a cluster whose structure is as yet unknown.

Tailoring of Transition Metal Alkoxides Via complexation For The Synthesis of Hybrid Organic-Inorganic Sols and Gels

The chemical control of hydrolysis-condensation reactions of transition metal alkoxides can be performed through the modification of the transition metal coordination sphere by using strong complexing ligands (SCL). Complexing organic groups can be bonded to the transition metal oxide network in two different ways, as network modifiers or network formers. Different illustrations of the role of complexing ligands on Ti(IV) and Zr(IV) alkoxides are presented. As a network modifier, SCL act as termination agents for condensation reactions allowing a control of particle growth. The complexing ligands being located at the periphery of the oxo core open many opportunities for colloid surface protection. SCL carrying organofunctional groups which exhibit non linear optical (NLO) properties have also been used as probes to study sol-gel transformations. SCL functionalized with organic polymerizable functions act as network formers. Hybrid organic-inorganic copolymers intimately interpenetrated on a nanometer size scale were synthesized from zirconium oxo polymers chemically bonded to polymeric methacrylate chains via a complexing function.

Synthesis of Hybrid Inorganic-Organic Sol-Gel Coatings for Optics

The synthesis of transparent hybrid organic-inorganic coatings obtained from condensation between alkoxysilane containing grafted dyes (azo dyes or phthalocyanines) and metal alkoxides precursors has been performed. The Red 17 azo dye, known for its high second order polarisability, was bonded to the silicon oxide network following two procedures: a silylation reaction between Red 17 and triethoxysilane; a coupling reaction between Red 17 and 3-isocyanatopropyltriethoxysilane. Silicon phthalocyanines (known for their third order polarisability and inverse saturable absorption properties) were incorporated into the silicon oxide network by a silylation reaction. Phthalocyanine doped transparent hybrid organic-inorganic coatings were obtained from condensation between diethoxymethylsilane and zirconium propoxide precursors.

Sol-Gel Synthesis of Hybrid Organic-Inorganic Tin Oxide Based Materials

RSn(OAmt)3 with R = n-butyl, n-butenyl or para-styryl, which are monomeric precursors, have been hydrolyzed. The so-obtained products have been characterized mainly by 119Sn NMR. In every cases, tin expands its coordination from 4 to 5 and 6, and hydrolysis yields tin oxo-hydroxo species of small size. For n-butyl and n-butenyl, a cage-like tin oxo-hydroxo cluster, {(RSn)12(μ3–O)14(μ2-OH)6}2+, was evidenced as the major compound formed. Organic polymerization of the unsaturated organic groups linked to tin was initiated on the hydrolysis products and yielded hybrid systems which can be pictured as tin oxo-hydroxo oligomers attached together by polymeric chains.