Crystal formation in kidney tissue is increasingly recognized as a major cause of severe or acute renal failure. Kidney biopsies are currently performed and analyzed using different staining procedures. Unfortunately, none of these techniques are able to distinguish the different Ca phosphates (e.g., amorphous or nanostructured Ca phosphate apatite, octacalcium phosphate, brushite…) or Ca oxalates (whewellite and weddellite). Moreover, the crystal’s morphology, a structural parameter proven as a major information to the clinician regarding kidney stones, is not taken into account. Such major limitations call for a different research approach, based on physicochemical techniques. Here we propose classical observations through field-emission scanning electron microscopy experiments combined with energy dispersive spectroscopy as well as measurements through Raman and μFourier transform Infra-Red Spectroscopy. If necessary, in the case of microcrystals, observations using cutting edge technology such as Synchrotron Radiation (SR) – FTIR or SR-UV visible spectroscopy can be subsequently performed on the same sample. Taken together this set of diagnostic tools will help clinicians gather information regarding the nature and the spatial distribution at the subcellular scale of different chemical phases present in kidney biopsies as well as on the crystal morphology and therefore obtain more precise diagnosis.
L'émail est un tissu unique chez les vertébrés, acellulaire, formé sur un échafaudage matriciel labile et hyperminéralisé. Les cellules épithéliales responsables de sa formation sont les améloblastes. Ces derniers sécrètent des protéines matricielles, secondairement détruites pendant la minéralisation. Cette séquence ordonnée implique que toute perturbation génétique ou environnementale produira une anomalie de l'émail indélébile et reconnaissable, dont la spécificité permettra d'identifier le processus cellulaire affecté. Les dents touchées permettront donc un diagnostic rétrospectif de l'évènement tératogène. Les avancées du domaine font des défauts de l'émail un outil pour les diagnostics moléculaires. Les multiples fonctions des peptides amélaires sont identifiées pas à pas, des mécanismes physico-chimiques de la minéralisation à la signalisation cellulaire, constituant une source d'innovations en médecine régénérative.
Dentin differs in composition and morphology depending on its anatomical location and circumstances of formation (1). Circumpulpal dentinogenesis patterns, either in a physiological or reparative c...
Background basic calcium phosphate (BCP) crystals are commonly found in osteoarthritis (OA) and are associated with cartilage destruction. BCP crystals induce in vitro catabolic responses with the production of metalloproteases and inflammatory cytokines such as interleukin-1 (IL-1). In vivo, IL-1 production induced by BCP crystals is both dependant and independent of NLRP3 inflammasome. We aimed to clarify 1/ the role of BCP crystals in cartilage destruction and 2/ the role of IL-1 and NLRP3 inflammasome in cartilage degradation related to BCP crystals. Methodology/ Principal Findings synovial membranes isolated from OA knees were analysed by alizarin Red and FTIR. Pyrogen free BCP crystals were injected into right knees of WT, NLRP3 -/-, ASC -/-, IL-1α -/- and IL-1β-/- mice and PBS was injected into left knees. To assess the role of IL-1, WT mice were treated by intra-peritoneal injections of anakinra, the IL-1Ra recombinant protein, or PBS. Articular destruction was studied at d4, d17 and d30 assessing synovial inflammation, proteoglycan loss and chondrocyte apoptosis. BCP crystals were frequently found in OA synovial membranes including low grade OA. BCP crystals injected into murine knee joints provoked synovial inflammation characterized by synovial macrophage infiltration that persisted at day 30, cartilage degradation as evidenced by loss of proteoglycan staining by Safranin-O and concomitant expression of VDIPEN epitopes, and increased chondrocyte apoptosis. BCP crystal-induced synovitis was totally independent of IL-1α and IL-1β signalling and no alterations of inflammation were observed in mice deficient for components of the NLRP3-inflammasome, IL-1α or IL-1β. Similarly, treatment with anakinra did not prevent BCP crystal effects. In vitro, BCP crystals elicited enhanced transcription of matrix degrading and pro-inflammatory genes in macrophages. Conclusions/ Significance intra-articular BCP crystals can elicit synovial inflammation and cartilage degradation suggesting that BCP crystals have a direct pathogenic role in OA. The effects are independent of IL-1 and NLRP3 inflammasome.
Background and objective:FAM20A gene mutations result in enamel renal syndrome (ERS) associated with amelogenesis imperfecta (AI), nephrocalcinosis, gingival fibromatosis, and impaired tooth eruption. FAM20A would control the phosphorylation of enamel peptides and thus enamel mineralization. Here, we characterized the structure and chemical composition of unerupted tooth enamel from ERS patients and healthy subjects. Methods: Tooth sections were analyzed by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), X-Ray Diffraction (XRD), and X-Ray Fluorescence (XRF). Results: SEM revealed that prisms were restricted to the inner-most enamel zones. The bulk of the mineralized matter covering the crown was formed by layers with varying electron-densities organized into lamellae and micronodules. Tissue porosity progressively increased at the periphery, ending with loose and unfused nanonodules also observed in the adjoining soft tissues. Thus, the enamel layer covering the dentin in all ERS patients (except a limited layer of enamel at the dentino-enamel junction) displayed an ultrastructural globular pattern similar to one observed in ectopic mineralization of soft tissue, notably in the gingiva of Fam20a knockout mice. XRD analysis confirmed the existence of alterations in crystallinity and composition (vs. sound enamel). XRF identified lower levels of calcium and phosphorus in ERS enamel. Finally, EDS confirmed the reduced amount of calcium in ERS enamel, which appeared similar to dentin. Conclusion: This study suggests that, after an initial normal start to amelogenesis, the bulk of the tissue covering coronal dentin would be formed by different mechanisms based on nano- to micro-nodule aggregation. This evocated ectopic mineralization process is known to intervene in several soft tissues in FAM20A gene mutant.
Spinodal decomposition in the TiO 2 – SnO 2 system produces TiO 2 rich/ SnO 2 rich nano‐wide lamellae. The high density of coherent interfaces is expected to reduce thermal conductivity of the ceramic without blocking electron transport. These semiconductors could therefore be candidates for environmental friendly oxide thermo‐electrics. However, dense materials are difficult to obtain by conventional sintering from a mixture of TiO 2 and SnO 2 powders due to evaporation of tin oxide. The article presents a novel route to produce, by aqueous co‐precipitation, Ti 0.5 Sn 0.5 O 2 nanopowders as precursors for dense ceramics. The nanostructure developed by spinodal decomposition inside the grains of the as obtained dense Ti 0.5 Sn 0.5 O 2 ceramic is shown to be comparable to that of porous Ti 0.5 Sn 0.5 O 2 ceramic obtained by conventional method.
The JJ stent constitutes a medical device extensively used nowadays by urologists in more than 40,000 patients per year in France. In this investigation, we characterize the surface state and the elastic properties of a set of JJ stents on which pathological calcifications are present. These encrustations have been identified by Fourier transform infrared spectroscopy. A surface examination by scanning electron microscopy indicates the existence of defects. The striking point of these observations is that black marks, present at the surface to help urologists during the operation, significantly alter the surface and may serve as nucleation centers. Moreover, elastic properties are not preserved when the indwelling time of JJ stents is longer than 12 wk. Such data may help industrial companies to develop new JJ stents, which avoid the formation of encrustations and help the clinician to optimize the lifetime of JJ stents in patients. Les sondes JJ constituent un dispositif médical largement utilisé de nos jours par les urologues chez plus de 40 000 patients par an en France. Dans cette étude, nous caractérisons l'état de surface et les propriétés élastiques d'un ensemble de sondes JJ sur lesquelles des calcifications pathologiques sont présentes. Ces incrustations ont été identifiées par spectrophotométrie infrarouge à transformée de Fourier. Un examen de surface par microscopie électronique à balayage indique l'existence de défauts. Le point marquant de ces observations vient du fait que les marques noires présentes à la surface pour aider les urologues pendant l'opération modifient de manière significative la surface et peuvent servir de sites de nucléation. De plus, les propriétés élastiques ne sont pas conservées lorsque le temps de séjour de ces sondes chez le patient est supérieur à 12 semaines. Ces données peuvent donc aider les industriels à développer de nouvelles sondes JJ évitant la formation d'incrustations et aider le clinicien à optimiser la durée de vie des sondes JJ chez les patients.
