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Briard A.,CNRS Jean Le Rond dAlembert Institute | Gomez T.,USTL | Mons V.,CNRS Jean Le Rond dAlembert Institute | Sagaut P.,Aix - Marseille University
Journal of Turbulence | Year: 2016

ABSTRACT: Homogeneous anisotropic turbulence has been widely studied in the past decades, both numerically and experimentally. Shear flows have received a particular attention because of the numerous physical phenomena they exhibit. In the present paper, both the decay and growth of anisotropy in homogeneous shear flows at high Reynolds numbers are revisited thanks to a recent eddy-damped quasi-normal Markovian closure adapted to homogeneous anisotropic turbulence. The emphasis is put on several aspects: an asymptotic model for the slow part of the pressure–strain tensor is derived for the return to isotropy process when mean velocity gradients are released. Then, a general decay law for purely anisotropic quantities in Batchelor turbulence is proposed. At last, a discussion is proposed to explain the scattering of global quantities obtained in DNS and experiments in sustained shear flows: the emphasis is put on the exponential growth rate of the kinetic energy and on the shear parameter. © 2016 Informa UK Limited, trading as Taylor & Francis Group.

Vert R.,French Atomic Energy Commission | Chicot D.,USTL | Decoopman X.,Lille Laboratory of Mechanics | Gruescu I.C.,University of Lille Nord de France | And 3 more authors.
Thin Solid Films | Year: 2011

In order to characterize the adhesion of nanostructured plasma-sprayed Y2O3-ZrO2 coatings presenting some geometrical specificities, it is here suggested to apply the Vickers Indentation Cracking (VIC) technique, which is capable of initiating a crack at the interface by performing the indentation test close to the interface within the substrate. This method renders it possible to overcome the difficulties concerning the characterization of the adhesion of nanostructured Y2O 3-ZrO2 (YSZ) coatings. It was suggested to calculate an adhesive stress parameter by employing two physical parameters, i.e., the critical load to initiate the crack and the indentation distance measured between the interface and the indent center. In addition, for the case of brittle coatings, the crack was found to deviate from the interface toward the coating. Under such conditions and on the basis of the critical point (given by the two parameters: load and indentation distance), a stress parameter representative of the cohesive properties of the coating was defined according to the crack deviation conditions. © 2011 Elsevier B.V. All rights reseved.

Verbeke S.,French Institute of Health and Medical Research | Verbeke S.,University of Lille Nord de France | Meignan S.,French Institute of Health and Medical Research | Meignan S.,University of Lille Nord de France | And 11 more authors.
Cellular Signalling | Year: 2010

The p75 neurotrophin receptor (p75NTR) plays a critical role in various neuronal and non-neuronal cell types by regulating cell survival, differentiation and proliferation. To evaluate the influence of p75NTR in breast cancer development, we have established and characterized breast cancer cells which stably overexpress p75NTR. We showed that p75NTR overexpression per se promoted cell survival to apoptogens with a concomitant slowdown of cell growth. The pro-survival effect is associated with an increased expression of the inhibitor of apoptosis protein-1 (c-IAP1), a decrease of TRAIL-induced cleavage of PARP, procaspase 9 and procaspase 3, and a decrease of cytochrome C release from the mitochondria. The anti-proliferative effect is due to a cell accumulation in G0/G1, associated with a decrease of Rb phosphorylation and an increase of p21waf1. Interestingly, inhibition of p21waf1 with siRNA not only restores proliferation but also abolishes the pro-survival effect of p75NTR, indicating the key role of p21waf1 in the biological functions of p75NTR. Finally, using a SCID mice xenograft model, we showed that p75NTR overexpression favors tumor growth and strongly increases tumor resistance to anti-tumoral treatment.Together, our findings suggest that p75NTR overexpression in breast tumor cells could favor tumor survival and contribute to tumor resistance to drugs. This provides a rationale to consider p75NTR as a potential target for the future design of innovative therapeutic strategies. © 2010 Elsevier Inc.

Romon R.,French Institute of Health and Medical Research | Romon R.,University of Lille Nord de France | Adriaenssens E.,USTL | Adriaenssens E.,French National Center for Scientific Research | And 9 more authors.
Molecular Cancer | Year: 2010

Background: Although several anti-angiogenic therapies have been approved in the treatment of cancer, the survival benefits of such therapies are relatively modest. Discovering new molecules and/or better understating signaling pathways of angiogenesis is therefore essential for therapeutic improvements. The objective of the present study was to determine the involvement of nerve growth factor (NGF) in breast cancer angiogenesis and the underlying molecular mechanisms.Results: We showed that both recombinant NGF and NGF produced by breast cancer cells stimulated angiogenesis in Matrigel plugs in immunodeficient mice. NGF strongly increased invasion, cord formation and the monolayer permeability of endothelial cells. Moreover, NGF-stimulated invasion was under the control of its tyrosine kinase receptor (TrkA) and downstream signaling pathways such as PI3K and ERK, leading to the activation of matrix metalloprotease 2 and nitric oxide synthase. Interestingly, NGF increased the secretion of VEGF in both endothelial and breast cancer cells. Inhibition of VEGF, with a neutralizing antibody, reduced about half of NGF-induced endothelial cell invasion and angiogenesis in vivo.Conclusions: Our findings provided direct evidence that NGF could be an important stimulator for breast cancer angiogenesis. Thus, NGF, as well as the activated signaling pathways, should be regarded as potential new targets for anti-angiogenic therapy against breast cancer. © 2010 Romon et al; licensee BioMed Central Ltd.

Lequette Y.,French National Institute for Agricultural Research | Garenaux E.,USTL | Garenaux E.,French National Center for Scientific Research | Tauveron G.,French National Institute for Agricultural Research | And 7 more authors.
Applied and Environmental Microbiology | Year: 2011

Bacillus cereus spores are surrounded by a loose-fitting layer called the exosporium, whose distal part is mainly formed from glycoproteins. The role played by the exosporium glycoproteins of B. cereus ATCC 14579 (BclA and ExsH) was investigated by considering hydrophobicity and charge, as well as the properties of spore adhesion to stainless steel. The absence of BclA increased both the isoelectric point (IEP) and hydrophobicity of whole spores while simultaneously reducing the interaction between spores and stainless steel. However, neither the hydrophobicity nor the charge associated with BclA could explain the differences in the adhesion properties. Conversely, ExsH, another exosporium glycoprotein, did not play a significant role in spore surface properties. The monosaccharide analysis of B. cereus ATCC 14579 showed different glycosylation patterns on ExsH and BclA. Moreover, two specific glycosyl residues, namely, 2-O-methyl-rhamnose (2-Me-Rha) and 2,4-O-methyl-rhamnose (2,4-Me-Rha), were attached to BclA, in addition to the glycosyl residues already reported in B. anthracis. © 2011, American Society for Microbiology.

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