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Osteogenesis imperfecta

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Osteogenesis imperfecta

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Osteogenesis imperfecta is caused by genetic defects of type-1collagen.These defects lead to abnormalities of the bone matrix organization which result clinically in a high fracture rate, skeleton deformities and short stature in patients suffering from this disease. Drug treatments that inhibit bone resorption or stimulate osteogenesis are currently being used/tested in order to preserve or improve the bone capital in these patients. ln this paper, we used the oim-1- mouse,a murine model of osteogenesis imperfecta, to investigate the effects of neutralizing sclerostin, which is a powerful endogenous inhibitor of osteoblasts by antagonization of Wnt and BMP growth factors.Starting from the premise that the use of an antisclerostin antibody may help stimulate osteogenesis,we attempted to demonstrate that it could improve skeletal parameters and increase growth.Methods. Four groups were studied: untreated oim-1- mice, oim_,_ mice treated with the sclerostin antibody and untreated and treated wild-type mice. We investigated the effects in vivo of the treatment on the entire mouse by clinimetric measurements and dual-energy X­ ray absorptiometry (DXA). After euthanasia, long bones were radiographed in order to perform a fracture count and a tibial length measurement; they were then analyzed by peripheral Quantitative Computed Tomography (pQCT) to analyze the bone minerai density (BMD) and biomechanical properties. Subsequently, non-decalcified cross-sections through the tibias were used, on the one hand, to obtain microradiographies, fluorescence images and classical stained sections, and, on the other hand, to perform a Fourier transform infrared spectroscopy in order to semi-quantitatively assess the chemical composition of the tibial bone cortex. The BMD and the length of the lumbar vertebrae were also assessed by pQCT, and these vertebrae were used for histomorphometrical measurements.Results. Weight and stature of the oim-/- mice, lower than the wild-type ones, were not increased with the treatment. This latter did not increase the length of the tibia and lumbar vertebrae, likely because the antisclereostin antibody was administered in the late growth. However, ail data concerning bone mass and, subsequently, bone strength, in both tibia and lumbal vertebrae, showed that antisclerotin antibody allowed the oim-1- mice to obtain values significantly higher than their untreated littermates and similar to the wild-type mice. Evaluation of the bone matrix quality by infrared spectroscopy gave mitigated results with respect to the expected results. As fracture counting showed a positive effect of the treatment by a decreased fracture rate, sclerostin antibody is a promising therapeutic approach for patients suffering from osteopenia. L'ostéogenèse imparfaite est due à des défauts génétiques du collagène de type 1. Il en résulte des anomalies de l'organisation de la matrice osseuse qui se traduisent cliniquement par une incidence élevée des fractures, des déformations squelettiques ainsi qu'une taille réduite des patients atteints. Les traitements médicamenteux inhibant la résorption osseuse ou stimulant l'ostéogenèse sont actuellement utilisés ou testés afin de préserver le capital osseux de ces patients, voire de l'augmenter. Dans ce mémoire, nous avons utilisé la souris oim-1-, modèle murin de l'ostéogenèse imparfaite, pour y étudier les effets de la neutralisation de la sclérostine, qui est un puissant inhibiteur endogène des ostéoblastes par antagonisme avec les facteurs de croissance Wnt et BMP. Partant du postulat qu'un anticorps anti-sclérostine permettra it de stimuler l'ostéogenèse, nous avons cherché à démontrer qu'il était susceptible d'améliorer les propriétés du squelette et d'augmenter la croissance des souris oim·J.Méthodes. Quatre groupes ont été étudiés : des souris oim-1- non-traitées, des souris oim-1- traitées à l'anticorps anti-sclérost ine, des souris wild-type non traitées et des souris wild­ type traitées. Ces souris ont été soumises in vivo à des mesures clinimétriques et à une ostéodensitométrie. Après euthanasie,les os longs ont été radiographiés afin de compter les fractures et de mesurer la longueur des tibias, puis analysés par pQCT (peripheral Quantitative Computed Tomography) pour l'estimation des propriétés biomécaniques et de la BMD (bone minerai density). Des coupes transversales non décalcifiées dans les tibias ont été microradiographiées, observées en fluorescence et colorées pour l'observation en lumière ordinaire. Certaines d'entre elles ont fait l'objet d'une analyse spectroscopique infrarouge à transformée de Fourier afin d'évaluer de manière semi-quantitative la composition chimique du cortex osseux tibial. Les vertèbres lombaires ont fait l'objet d'une mesure de la BMD et de leur longueur pQCT, ainsi que d'une analyse histomorphométrique.Résultats. Le poids et la taille des souris oim·1-, inférieurs à ceux des souris wild-type, ne sont pas augmentés avec le traitement. Celui-ci n'a pas entraîné de différence de longueur des tibias ni des vertèbres lombaires, vraisemblablement en raison de l'administration de l'anticorps anti-sclérosine en fin de croissance. Par contre, tous les paramètres reflétant la masse osseuse et, par extension, sa résistance mécanique, tant au niveau du tibia que des vertèbres lombaires, ont montré que l'anticorps anti-sclérostine permet aux souris oim-/­ d'atteindre des va leurs significativement supérieures à celles de leurs congénères non traitées et similaires à celles des souris wild-type. Les mesures préliminaires de la qualité de la matrice osseuse (spectroscopie infrarouge) ont donné lieu à des résultats mitigés. a diminution du nombre des fractures associée à ce gain de masse osseuse chez les sour is traitées suggère que l'anticorps anti-sclérostine constitue une approche thérapeutique prometteuse pour les personnes atteintes d'ostéopénie.

Sost protein, mouse --- Osteogenesis Imperfecta

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Osteogenesis Imperfecta is the first translational reference professionals can turn to for a source of comprehensive information on this disorder. Although several reviews of the field have been published in various journals, there is no other single source for a compendium of current information. Separate chapters discuss each of the several clinical features of OI. Ethical issues related to OI are discussed, as is the importance of nutrition in managing the OI child and the OI adult. The role of physical medicine and rehabilitation for OI patients is also presented, along with the

Osteogenesis imperfecta. --- Brittle bones --- Fragilitas ossium --- Lobstein's disease --- Osteogenesis imperfecta congenita --- Osteogenesis imperfecta tarda --- Osteopsathyrosis --- Bones --- Cartilage --- Collagen diseases --- Dwarfism --- Muscle hypotonia --- Osteoporosis --- Diseases

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This book illustrates the exciting possibilities being opened up by X-ray computed tomography (CT) to follow the behavior of materials under conditions as close as possible to those encountered during their manufacture or in operation.The scientific chapters selected for this book describe results obtained using synchrotron or laboratory devices during in situ or ex situ experiments. They characterize microstructures across length scales ranging from tens of nanometers to a few tens of micrometers.In this collection, X-ray CT shines a light on the mechanical properties of engineering materials, such as aluminum or magnesium alloys, stainless steel, aluminum, polymer composites, or ceramic foam. In these experiments, X-ray CT is able to image and quantify the damage occurring during tensile, compression, indentation, or fatigue tests.Of course, X-ray CT can illuminate the structure and behavior of natural materials too. Here it is applied to bone or natural snow to study their mechanical behavior, as well as materials from the agri-food sector. Its versatility is exemplified by analyses of topics as diverse as the removal of olive oil from kitchen sponges by squeezing and rinsing, to the effect of temperature changes on the structure of ice cream.

in-situ X-ray computed tomography --- thermal-mechanical loading --- polymer bonded explosives --- mesoscale characterization --- structure evolution --- particle morphology --- heat treatment --- aluminum cast alloy --- mechanical properties --- Ostwald ripening --- nanotomography --- phase-contrast imaging --- tomographic reconstruction --- dynamic tomography --- motion compensation --- projection-based digital volume correlation --- X-ray μCT --- in-situ experiments --- flow cell --- alkaline manganese batteries --- X-ray tomography --- in operando --- in situ --- zinc powder --- laser powder bed fusion --- additive manufacturing --- in-situ imaging --- Ti6Al4V --- lattice structures --- mechanics --- corrosion --- biomaterial --- battery --- aluminum foams --- intermetallics --- finite element analysis --- damage --- polycrystal plasticity --- X-ray diffraction imaging --- topotomography --- in situ experiment --- finite element simulation --- lattice curvature --- rocking curve --- ice cream --- microstructure --- tomography --- ice crystals --- coarsening --- soft solids --- bone --- X-ray radiation --- tissue damage --- SR-microCT --- digital volume correlation --- temperature control --- electrochemical cell design --- batteries --- helical CT --- contrast agent --- high cycle fatigue (HCF) --- fibre break --- fibre tows --- Freeze Foaming --- in situ computed tomography --- non-destructive testing --- bioceramics --- aging --- crack initiation and propagation --- damage modes --- osteoporosis --- osteogenesis imperfecta --- porosity --- bone matrix quality --- micro-CT --- snow grains --- snow microstructure --- snow properties --- pore morphology --- voids --- fiber-reinforced concrete --- CT scan technology --- DIP software --- X-ray tomography (X-ray CT) --- 3D image analysis --- hydrogen embrittlement --- stainless steel --- in-situ X-ray computed tomography --- thermal-mechanical loading --- polymer bonded explosives --- mesoscale characterization --- structure evolution --- particle morphology --- heat treatment --- aluminum cast alloy --- mechanical properties --- Ostwald ripening --- nanotomography --- phase-contrast imaging --- tomographic reconstruction --- dynamic tomography --- motion compensation --- projection-based digital volume correlation --- X-ray μCT --- in-situ experiments --- flow cell --- alkaline manganese batteries --- X-ray tomography --- in operando --- in situ --- zinc powder --- laser powder bed fusion --- additive manufacturing --- in-situ imaging --- Ti6Al4V --- lattice structures --- mechanics --- corrosion --- biomaterial --- battery --- aluminum foams --- intermetallics --- finite element analysis --- damage --- polycrystal plasticity --- X-ray diffraction imaging --- topotomography --- in situ experiment --- finite element simulation --- lattice curvature --- rocking curve --- ice cream --- microstructure --- tomography --- ice crystals --- coarsening --- soft solids --- bone --- X-ray radiation --- tissue damage --- SR-microCT --- digital volume correlation --- temperature control --- electrochemical cell design --- batteries --- helical CT --- contrast agent --- high cycle fatigue (HCF) --- fibre break --- fibre tows --- Freeze Foaming --- in situ computed tomography --- non-destructive testing --- bioceramics --- aging --- crack initiation and propagation --- damage modes --- osteoporosis --- osteogenesis imperfecta --- porosity --- bone matrix quality --- micro-CT --- snow grains --- snow microstructure --- snow properties --- pore morphology --- voids --- fiber-reinforced concrete --- CT scan technology --- DIP software --- X-ray tomography (X-ray CT) --- 3D image analysis --- hydrogen embrittlement --- stainless steel