90 research outputs found
Sclerostin does not play a major role in the pathogenesis of skeletal complications in type 2 diabetes mellitus
In contrast to previously reported elevations in serum sclerostin levels in diabetic patients, the present study shows that the impaired bone microarchitecture and cellular turnover associated with type 2 diabetes mellitus (T2DM)-like conditions in ZDF rats are not correlated with changes in serum and bone sclerostin expression. INTRODUCTION: T2DM is associated with impaired skeletal structure and a higher prevalence of bone fractures. Sclerostin, a negative regulator of bone formation, is elevated in serum of diabetic patients. We aimed to relate changes in bone architecture and cellular activities to sclerostin production in the Zucker diabetic fatty (ZDF) rat. METHODS: Bone density and architecture were measured by micro-CT and bone remodelling by histomorphometry in tibiae and femurs of 14-week-old male ZDF rats and lean Zucker controls (n = 6/group). RESULTS: ZDF rats showed lower trabecular bone mineral density and bone mass compared to controls, due to decreases in bone volume and thickness, along with impaired bone connectivity and cortical bone geometry. Bone remodelling was impaired in diabetic rats, demonstrated by decreased bone formation rate and increased percentage of tartrate-resistant acid phosphatase-positive osteoclastic surfaces. Serum sclerostin levels (ELISA) were higher in ZDF compared to lean rats at 9 weeks (+40 %, p < 0.01), but this difference disappeared as their glucose control deteriorated and by week 14, ZDF rats had lower sclerostin levels than control rats (-44 %, p < 0.0001). Bone sclerostin mRNA (qPCR) and protein (immunohistochemistry) were similar in ZDF, and lean rats at 14 weeks and genotype did not affect the number of empty osteocytic lacunae in cortical and trabecular bone. CONCLUSION: T2DM results in impaired skeletal architecture through altered remodelling pathways, but despite altered serum levels, it does not appear that sclerostin contributes to the deleterious effect of T2DM in rat bone
First order isotropic - smectic-A transition in liquid crystal-aerosil gels
The short-range order which remains when the isotropic to smectic-A
transition is perturbed by a gel of silica nanoparticles (aerosils) has been
studied using high-resolution synchrotron x-ray diffraction. The gels have been
created \textit{in situ} in decylcyanobiphenyl (10CB), which has a strongly
first-order isotropic to smectic-A transition. The effects are determined by
detailed analysis of the temperature and gel density dependence of the smectic
structure factor. In previous studies of the continuous nematic to smectic-A
transition in a variety of thermotropic liquid crystals the aerosil gel
appeared to pin, at random, the phase of the smectic density modulation. For
the isotropic to smectic-A transition the same gel perturbation yields
different results. The smectic correlation length decreases more slowly with
increasing random field variance in good quantitative agreement with the effect
of a random pinning field at a transition from a uniform phase directly to a
phase with one-dimensional translational order. We thus compare the influence
of random fields on a \textit{freezing} transition with and without an
intervening orientationally ordered phase.Comment: 8 pages, 8 figure
Lasting organ-level bone mechanoadaptation is unrelated to local strain
Bones adapt to mechanical forces according to strict principles predicting straight shape. Most bones are, however, paradoxically curved. To solve this paradox, we used computed tomographyâbased, four-dimensional imaging methods and computational analysis to monitor acute and chronic whole-bone shape adaptation and remodeling in vivo. We first confirmed that some acute load-induced structural changes are reversible, adhere to the linear strain magnitude regulation of remodeling activities, and are restricted to bone regions in which marked antiresorptive actions are evident. We make the novel observation that loading exerts significant lasting modifications in tibial shape and mass across extensive bone regions, underpinned by (re)modeling independent of local strain magnitude, occurring at sites where the initial response to load is principally osteogenic. This is the first report to demonstrate that bone loading stimulates nonlinear remodeling responses to strain that culminate in greater curvature adjusted for load predictability without sacrificing strength
Use of satellite observations for operational oceanography: recent achievements and future prospects
The paper gives an overview of the development of satellite oceanography over the past five years focusing on the most relevant issues for operational oceanography. Satellites provide key essential variables to constrain ocean models and/or serve downstream applications. New and improved satellite data sets have been developed and have directly improved the quality of operational products. The status of the satellite constellation for the last five years was, however, not optimal. Review of future missions shows clear progress and new research and development missions with a potentially large impact for operational oceanography should be demonstrated. Improvement of data assimilation techniques and developing synergetic use of high resolution satellite observations are important future priorities
Evaluating the performance of the OC5 algorithm of IFREMER for the highly turbid waters of RĂo de la Plata
An Approach to Developing Numeric Water Quality Criteria for Coastal Waters Using the SeaWiFS Satellite Data Record
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