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Recent reports have suggested that SDF (Stromal cell-derived factor)-1α- CXCR4 axis has a direct effect on stem and progenitor cell recruitment in muscle and neural tissue repair after injury. No information is available about SDF-1α or CXCR4 in dental tissues. The aim of this study was to assess the expression of SDF-1α and its receptor, CXCR4, in healthy or inflamed human dental pulp and to evaluate the effects of SDF-1α on dental pulp cells (DPCs) in both proliferation and migration in vitro. Immunohistochemical staining and RT-PCR detected weak expression of SDF-1α and CXCR4 in healthy dental pulp and strong expression of SDF-1a and CXCR4 in inflamed dental pulp. An MTT assay demonstrated that SDF-1α could not promote DPCs proliferation. A transmigration assay, however, indicated that SDF-1α enhanced DPCs migration, and which could be abolished by anti-CXCR4 antibodies. Taken together, these results imply that the SDF-1α-CXCR4 axis may play a role in the recruitment of CXCR4-positive DPCs toward the damaged sites

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The transcription factor hypoxia-inducible factor (HIF)-1 plays a central physiological role in oxygen and energy homeostasis, and is activated during hypoxia by stabilization of the subunit HIF-1α. Recent studies have demonstrated that non-hypoxic stimuli can also activate HIF-1α in a cell-specific manner. Here, we demonstrate that stimulation of BEAS-2B cells and primary human bronchial epithelial cells by proinflammatory cytokines TNFα/IL-4 strongly induced expression and transcriptional activity of HIF-1α under normoxic conditions and amplified hypoxic HIF-1α activation. TNFα/IL-4 stimulated de novo HIF-1α gene transcription and translation rather than affected HIF-1α protein degradation and mRNA decay process. The activation of HIF-1α by TNFα/IL-4 was countered by the phosphoinositol 3-kinase (PI3K) inhibitor LY-294002 and rapamycin, an antagonist of mammalian target of rapamycin (mTOR), but not by inhibition of the MAPK pathway. In line, TNFα/IL-4 also activated NF-κB, whereas blocking of NF-κB by an inhibitor or silencing NF-κB subunit p65 attenuated HIF-1α activation by TNFα/IL-4. We also found the collaborative induction of VEGF, a potent angiogenic factor required for airway remodeling, by TNFα/IL-4 and hypoxia partially via HIF-1α pathway in BEAS-2B cells. This study reports the previously unsuspected collaborative regulation of HIF-1α by TNFα/IL-4 and hypoxia in bronchial epithelial cells partially via PI3K-mTOR and NF-κB pathway, and thereby will lead to the elucidation of the importance of HIF-1 in integrating inflammatory and hypoxic response in the pathogenesis of airway diseases.

Isoflurane preconditioning can attenuate pulmonary proinflammatory cytokine release and decrease the mortality induced by severe sepsis. Early protection seems to be mediated partly through inhibition of iNOS-NO pathway activation.

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International audienceThe problem of the finite axisymmetric deformation of a thick-walled circular cylindrical elastic tube subject to pressure on its external lateral boundaries and zero displacement on its ends is formulated for an incompressible isotropic neo-Hookean material. The formulation is fully nonlinear and can accommodate large strains and large displacements. The governing system of nonlinear partial differential equations is derived and then solved numerically using the Cþþ based object-oriented finite element library Libmesh. The weighted residual-Galerkin method and the Newton-Krylov nonlinear solver are adopted for solving the governing equations. Since the nonlinear problem is highly sensitive to small changes in the numerical scheme, convergence was obtained only when the analytical Jacobian matrix was used. A Lagrangian mesh is used to discretize the governing partial differential equations. Results are presented for different parameters, such as wall thickness and aspect ratio, and comparison is made with the corresponding linear elasticity formulation of the problem, the results of which agree with those of the nonlinear formulation only for small external pressure. Not surprisingly, the nonlinear results depart significantly from the linear ones for larger values of the pressure and when the strains in the tube wall become large. Typical nonlinear characteristics exhibited are the ''corner bulging'' of short tubes, and multiple modes of deformation for longer tubes

International audienceIn this paper, we consider bifurcation from a circular cylindrical deformed configuration of a thick-walled circular cylindrical tube of incompressible isotropic elastic material subject to combined axial loading and external pressure. In particular , we examine both axisymmetric and asymmetric modes of bifurcation. The analysis is based on the three-dimensional incremental equilibrium equations, which are derived and then solved numerically for a specific material model using the Adams–Moulton method. We assess the effects of wall thickness and the ratio of length to (external) radius on the bifur-cation behaviour