21 research outputs found

    Response of a multi-domain continental margin to compression: study from seismic reflection-refraction and numerical modelling in the Tagus Abyssal Plain

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    The effects of the Miocene through Present compression in the Tagus Abyssal Plain are mapped using the most up to date available to scientific community multi-channel seismic reflection and refraction data. Correlation of the rift basin fault pattern with the deep crustal structure is presented along seismic line IAM-5. Four structural domains were recognized. In the oceanic realm mild deformation concentrates in Domain I adjacent to the Tore-Madeira Rise. Domain 2 is characterized by the absence of shortening structures, except near the ocean-continent transition (OCT), implying that Miocene deformation did not propagate into the Abyssal Plain, In Domain 3 we distinguish three sub-domains: Sub-domain 3A which coincides with the OCT, Sub-domain 3B which is a highly deformed adjacent continental segment, and Sub-domain 3C. The Miocene tectonic inversion is mainly accommodated in Domain 3 by oceanwards directed thrusting at the ocean-continent transition and continentwards on the continental slope. Domain 4 corresponds to the non-rifted continental margin where only minor extensional and shortening deformation structures are observed. Finite element numerical models address the response of the various domains to the Miocene compression, emphasizing the long-wavelength differential vertical movements and the role of possible rheologic contrasts. The concentration of the Miocene deformation in the transitional zone (TC), which is the addition of Sub-domain 3A and part of 3B, is a result of two main factors: (1) focusing of compression in an already stressed region due to plate curvature and sediment loading; and (2) theological weakening. We estimate that the frictional strength in the TC is reduced in 30% relative to the surrounding regions. A model of compressive deformation propagation by means of horizontal impingement of the middle continental crust rift wedge and horizontal shearing on serpentinized mantle in the oceanic realm is presented. This model is consistent with both the geological interpretation of seismic data and the results of numerical modelling. (C) 2008 Elsevier B.V. All rights reserved.Instituto Nacional de Engenharia, Tecnologia e Inovacao(INETI); Landmark Graphics Corporation; Landmark University Grant Program; LATTEX/IDL [ISLF-5-32]; FEDERinfo:eu-repo/semantics/publishedVersio

    Invasive candidiasis

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    Contains fulltext : 193079.pdf (publisher's version ) (Closed access

    Bacteria-triggered CD4+ T regulatory cells suppress Helicobacter hepaticus-induced colitis

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    We have previously demonstrated that interleukin (IL)-10–deficient (IL-10 knockout [KO]) but not wild-type (WT) mice develop colitis after infection with Helicobacter hepaticus. Here, we show that infected recombination activating gene (RAG) KO mice develop intestinal inflammation after reconstitution with CD4+ T cells from IL-10 KO animals and that the cotransfer of CD4+ T cells from H. hepaticus–infected but not uninfected WT mice prevents this colitis. The disease-protective WT CD4+ cells are contained within the CD45RBlow fraction and unexpectedly were found in both the CD25+ and the CD25- subpopulations of these cells, their frequency being higher in the latter. The mechanism by which CD25+ and CD25- CD45RBlow CD4+ cells block colitis involves IL-10 and not transforming growth factor (TGF)-ß, as treatment with anti–IL-10R but not anti–TGF-ß monoclonal antibody abrogated their protective effect. In vitro, CD45RBlow CD4+ cells from infected WT mice were shown to produce IL-10 and suppress interferon-{gamma} production by IL-10 KO CD4+ cells in an H. hepaticus antigen–specific manner. Together, our data support the concept that H. hepaticus infection results in the induction in WT mice of regulatory T cells that prevent bacteria-induced colitis. The induction of such cells in response to gut flora may be a mechanism protecting normal individuals against inflammatory bowel disease

    The Janus face of Bartonella quintana recognition by Toll-like receptors (TLRs): a review.

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    Contains fulltext : 70849.pdf (publisher's version ) (Closed access)Bartonella quintana (B. quintana) is a facultative, intracellular bacterium, which causes trench fever, chronic bacteraemia and bacillary angiomatosis. Little is known about the recognition of B. quintana by the innate immune system. In this review, we address the impact of Toll-like receptors (TLRs) on the recognition of B. quintana and the activation of the host defense. When experimental models using human mononuclear cells, transfected CHO cells, or TLR2-/- and TLR4-/- mice were used, differential effects of TLR2 and TLR4 have been observed. B. quintana micro-organisms stimulated cytokine production through TLR2-mediated signals, whereas no role for TLR4 in the recognition of this pathogen was observed. When single, water-phenol extraction was performed, B. quintana LPS, stimulated cytokine production in a TLR2-dependent manner. However, when double extraction was performed in order to generate highly purified LPS, B. quintana LPS entirely lost its capacity to stimulate cytokines, demonstrating that non-LPS components of B. quintana are responsible for the recognition through TLR2. Moreover, B. quintana LPS was shown to be a potent antagonist of Toll-like receptor 4 (TLR4). In conclusion, B. quintana is an inducer of cytokines through TLR2-, but not TLR4-, dependent mechanisms. This stimulation is induced by bacterial components other than lipopolysaccharide. B. quintana LPS is a naturally occurring antagonist of Toll-like receptor 4 (TLR4). In view of the role played by TLR4 in inflammation, B. quintana LPS may be useful as an anti-TLR4 agent with therapeutic potential in both infections and autoimmune inflammation
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