Alteration of Interendothelial Adherens Junctions Following Tumor Cell-Endothelial Cell Interaction in Vitro

in Experimental Cell Research (1997), 237(2), 347-56

The integrity of the vascular endothelium is mainly dependent upon the organization of interendothelial adherens junctions (AJ). These junctions are formed by the homotypic interaction of a transmembrane ... [more ▼]

The integrity of the vascular endothelium is mainly dependent upon the organization of interendothelial adherens junctions (AJ). These junctions are formed by the homotypic interaction of a transmembrane protein, vascular endothelial cadherin (VE-cadherin), which is complexed to an intracellular protein network including alpha-, beta-, and gamma-catenin. Additional proteins such as vinculin and alpha-actinin have been suggested to link the VE-cadherin/catenin complex to the actin-based cytoskeleton. During the process of hematogenous metastasis, circulating tumor cells must disrupt these intercellular junctions in order to extravasate. In the present study, we have investigated the influence of tumor cell-endothelial cell interaction upon interendothelial AJ. We show that human breast adenocarcinoma cells (MCF-7), but not normal human mammary epithelial cells, induce a rapid endothelial cell (EC) dissociation which correlates with the loss of VE-cadherin expression at the site of tumor cell-EC contact and with profound changes in vinculin distribution and organization. This process could not be inhibited by metalloproteinase nor serine protease inhibitors. Immunoprecipitations and Western blot analysis demonstrate that the overall expression of VE-cadherin and vinculin as well as the composition of the VE-cadherin/catenins complex are not affected by tumor cells while the tyrosine phosphorylation status of proteins within the complex is significantly altered. Our data suggest that tumor cells modulate AJ protein distribution and phosphorylation in EC and may, thereby, facilitate EC dissociation. [less ▲]

Influence de l'évolution de la phytotechnie du blé sur le raisonnement de la protection fongicide

in Conférence internationale sur les maladies des plantes (1997, December 03)

Au cours de la dernière décennie, le rendement des cultures de blé a largement progressé essentiellement grâce à l'amélioration génétique et aux performances accrues en matière de fertilisation et de ... [more ▼]

Au cours de la dernière décennie, le rendement des cultures de blé a largement progressé essentiellement grâce à l'amélioration génétique et aux performances accrues en matière de fertilisation et de protection de la culture. L'amélioration génétique a petit à petit transformé la plante de blé: l'accroissement du potentiel de rendement repose principalement sur l'amélioration des composantes du rendement déterminées tardivement: fertilité des épis et capacité de remplissage des grains. La part de matière sèche produite à partir du stade dernière feuille devient prépondérante. La fertilisation azotée de la culture s'adapte à cette évolution: report d'une partie de la fumure en cours de montaison (France), renforcement de la fraction de la fumure apportée au stade dernière feuille (Belgique). Le glissement d'une part de la fumure azotée vers des stades plus avancés de la culture modifie les données de l'interaction entre les maladies cryptogamiques et la fumure la pression des maladie diminue en début de montaison mais s'accentue en fin de végétation. Dès lors, les programmes de protection fongicides devraient privilégier la protection des organes supérieurs de la plante: dernière feuille et épi. Les nouveaux fongicides de la famille des strobilurines sont dans cette optique des outils très intéressants. [less ▲]

Spectroscopic analysis of the Alpha Centauri system

in Astronomy and Astrophysics (1997), 328

A detailed spectroscopic analysis of the two components of the binary system alpha Centauri has been carried out on the basis of extensive high resolution and high signal-to-noise spectra. The ... [more ▼]

A detailed spectroscopic analysis of the two components of the binary system alpha Centauri has been carried out on the basis of extensive high resolution and high signal-to-noise spectra. The temperatures of the stars have been determined from the Fei excitation equilibrium and checked from the H_alpha line wings. The abundances of 17 elements have been obtained and indicate a general overabundance of 0.24 dex relative to the Sun, with no significant difference between the two stars. All elements analysed, from CNO to the iron peak, show basically the same overabundance. Only nickel seems to be significantly more overabundant, while the neutron capture elements appear less enhanced. Based on observations carried out at the European Southern Observatory (La Silla, Chile) [less ▲]

Small-angle X-ray scattering and small-angle neutron scattering studies of liquid-crystalline halato(semi)telechelic polymers

in Journal of Applied Crystallography (1997), 30(6), 1075-1083

Model liquid-crystalline ionomers have been synthesized, which consist of low molecular weight (700-49000) linear ω- and α,ω-sodium sulfonate- and carboxylato-poly(styrenes or isoprenes) selectively end ... [more ▼]

Model liquid-crystalline ionomers have been synthesized, which consist of low molecular weight (700-49000) linear ω- and α,ω-sodium sulfonate- and carboxylato-poly(styrenes or isoprenes) selectively end-capped at one or both end(s) with an ionic mesogenic group. These compounds are referred to as liquid-crystalline halato(semi)telechelic polymers [LC H(S)TPs] A combination of small-angle X-ray scattering and small-angle neutron scattering studies on these LC H(S)TPs clearly shows the usual ionic peak related to interparticle interference between the ionic aggregates and a peak which can be related to the organization of a smectic mesophase. This mesogenic peak is generally masked by the foot of the broad ionic peak. The ionic peak Bragg spacing is much larger in the LC H(S)TP than in the H(S)TP precursor; This increased interaggregate distance results from the hindrance due to the mesogenic organization and from the restricted mobility experienced by the chains closely attached to the mesogen layers. As a rule, the lower the glass transition temperature of the polymeric matrix, the better the definition of the ionic peak, The ionic peak is well defined as long as the temperature is lower than the temperature of transition from solid to smectic phase (32.3 K). At higher temperatures, the ionic peak intensity decreases with increasing temperature. [less ▲]

Characterization of polyacrylonitrile films grafted onto nickel by ellipsometry, atomic force microscopy and X-ray reflectivity

in Thin Solid Films (1997), 310(1-2), 148-155

The thickness and roughness of polyacrylonitrile films electrografted on a nickel surface have been measured by ellipsometry, atomic force microscopy and X-ray reflectivity. From combined ellipsometry and ... [more ▼]

The thickness and roughness of polyacrylonitrile films electrografted on a nickel surface have been measured by ellipsometry, atomic force microscopy and X-ray reflectivity. From combined ellipsometry and X-ray reflectivity measurements, accurate values for the refractive indices of polyacrylonitrile and nickel have been derived at a 6328-Åwavelength. Dependence of the film thickness on the monomer concentration has been quantified for the first time. Furthermore, the thickness of the polyacrylonitrile (PAN) film is related to the nature of the solvent, depending on whether it is a good solvent for PAN (dimethylformamide; DMF) or not (acetonitrile; ACN). [less ▲]

"Théories du texte et apprentissage des langues : les grands axes d'une approche interdisciplinaire"

in Travaux de linguistique : revue internationale de linguistique Française (1997), 34

HST confirmation of the lensed quasar J03.13.

in Astronomy and Astrophysics (1997), 327

In order to definitely prove the claim by Claeskens et al. (1996A&A...305L...9C) that J03.13 is a doubly imaged quasar, WFPC2 direct imaging and FOS spectroscopy of this compact system have been obtained ... [more ▼]

In order to definitely prove the claim by Claeskens et al. (1996A&A...305L...9C) that J03.13 is a doubly imaged quasar, WFPC2 direct imaging and FOS spectroscopy of this compact system have been obtained with HST. These textbook case observations clearly show that J03.13 consists of two point-like images separated by 0.849"+/-0.001" with a magnitude difference of 2.14+/-0.03 in V and I. We see no trace of a lensing galaxy. From the FOS observations, we find that J03.13 A and B have identical spectra within the measurement uncertainties. The data also show that spectroscopic contamination of B by A is negligible. We do confirm the redshift z=2.545 for J03.13 A and B (emission-lines due to Ly-beta lambda1025 and O VI lambdalambda1031, 1037 are also detected), first derived from an unresolved ground-based spectrum of the two components by Claeskens et al. We also find that the absorption line system at z=2.344 (CIV and Ly-alpha) is present in the spectra of A and B. On the contrary, the absorption line system at z=1.085 (MgII) is only present in the spectrum of J03.13 A. If this latter system is associated with the lens, we may expect that image A consists of two radially merging images with a very small angular separation. From the WFPC2 imagery, we can rule out the presence of a third component fainter than A by up to 5.2mag. with an angular separation >=0.13". [less ▲]

The use of a food frequency questionnaire in a adolescent population

in Gaceta Sanitaria (1997, November), 11(suppl 2), 37

Etude morphologique du petit sésamoïde du cheval. Relations éventuelles avec la pathologie.

Doctoral thesis (1997)

Pinch Point Method in Optimization of Advanced Combined Cycles

Poster (1997, October 05)

The pinch point method has been developed to identify energy saving opportunities in industrial processes, The use of the composite curves allows to compute the minimum energy requirement of a process and ... [more ▼]

The pinch point method has been developed to identify energy saving opportunities in industrial processes, The use of the composite curves allows to compute the minimum energy requirement of a process and to determine optimal heat exchange between hot urd cold streams. The use of MILP (Mixed Integer Linear Programming) optimisation method allows to extend the approach to solve combined heat and power problems. The method is applied here to determine the optimal configuration of combined cycles, It allows to maximize the mechanical power production without having to consider the heat exchangersc onfiguration in the boiler nor in the preheating section. The method is also used to compute the steam extractions or productions and their optimal pressure levels that maximize the mechanical power produced From these results, the heat exchangers network structure is then determined. Three situations are analyzed: l) the heat recovery in a classical boiler using air preheating, 2) the gas turbine combined cycle and. 3) the " isothermal" gas turbine. The " isothermal" gas turbine is an innovative promising technology that uses a partial oxydation reactor followed by a staged combustion between the expansion stages to reach a quasi isothermal profile during the expansion. This allows to reduce the exergy losses in the gas turbine. The resulting flue gases are used in a combined cycle optimized with the method presented here. Diffirent configurations are discussed We show that the structure of combined cycles may strongly differ from one to another. [less ▲]