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See detailReactivity of penicillin-binding proteins with peptidoglycan-mimetic beta-lactams: what's wrong with these enzymes?
Josephine, Helen R.; Charlier, Paulette ULg; Davies, Christopher et al

in Biochemistry (2006), 45(51), 15873-83

Beta-lactams exert their antibiotic action through their inhibition of bacterial DD-peptidases (penicillin-binding proteins). Bacteria, in general, carry several such enzymes localized on the outside of ... [more ▼]

Beta-lactams exert their antibiotic action through their inhibition of bacterial DD-peptidases (penicillin-binding proteins). Bacteria, in general, carry several such enzymes localized on the outside of their cell membrane to catalyze the final step in cell wall (peptidoglycan) synthesis. They have been classified into two major groups, one of high molecular weight, the other of low. Members of the former group act as transpeptidases in vivo, and their inhibition by beta-lactams leads to cessation of bacterial growth. The latter group consists of DD-carboxypeptidases, and their inhibition by beta-lactams is generally not fatal to bacteria. We have previously shown that representatives of the former group are ineffective at catalyzing the hydrolysis/aminolysis of peptidoglycan-mimetic peptides in vitro [Anderson et al. (2003) Biochem. J. 373, 949-955]. The theme of these experiments is expanded in the present paper where we describe the synthesis of a series of beta-lactams (penicillins and cephalosporins) containing peptidoglycan-mimetic side chains and the kinetics of their inhibition of a panel of penicillin-binding proteins spanning the major classes (Escherichia coli PBP 2 and PBP 5, Streptococcus pneumoniae PBP 1b, PBP 2x and PBP 3, the Actinomadura R39 DD-peptidase, and the Streptomyces R61 DD-peptidase). The results of these experiments mirror and expand the previous results with peptides. Neither peptides nor beta-lactams with appropriate peptidoglycan-mimetic side chains react with the solubilized constructs of membrane-bound penicillin binding proteins (the first five enzymes above) at rates exceeding those of generic analogues. Such peptides and beta-lactams do react at greatly enhanced rates with certain soluble low molecular weight enzymes (R61 and R39 DD-peptidases). The former result is unexpected and interesting. Why do the majority of penicillin-binding proteins not recognize elements of local peptidoglycan structure? Possible answers are discussed. That this question needs to be asked casts fascinating shadows on current studies of penicillin-binding proteins for new drug design. [less ▲]

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See detailRegulation of MAP kinases by the VHR dual-specific phosphatase: implications for cell growth and differentiation.
Cerignoli, Fabio; Rahmouni, Souad ULg; Ronai, Ze'ev et al

in Cell Cycle (Georgetown, Tex.) (2006), 5(19), 2210-5

Although it is well established that a transient activation of the mitogen-activated protein kinases Erk and Jnk is a crucial step in most growth promoting signaling pathways, it has also been ... [more ▼]

Although it is well established that a transient activation of the mitogen-activated protein kinases Erk and Jnk is a crucial step in most growth promoting signaling pathways, it has also been demonstrated that a prolonged activation of these kinases can induce differentiation, cell cycle arrest, and cell senescence. We recently found that the expression of the 21-kDa human Vaccinia H1-related (VHR) dual-specific phosphatase fluctuates during cell cycle progression and affects Erk and Jnk activity in a cell cycle-dependent manner. Cells lacking VHR arrested at the G(1)/S and G(2)/M transitions of the cell cycle and exhibited senescence phenotypes. Cells lacking VHR upregulated p21(Cip/Waf1) and downregulated many genes for cell cycle regulators, DNA replication, transcription, and mRNA processing. In the absence of VHR, the serum-induced activation of Jnk and Erk was further elevated and was required for the G(1)/S and G(2)/M blocks, which were attenuated upon Jnk and Erk inhibition. Collectively, VHR provides a long sought layer in the regulation of Jnk and Erk during cell cycle progression thereby contributing to cell cycle arrest, differentiation or senescence. [less ▲]

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See detailMicrobial ecology of the closed artificial ecosystem MELiSSA (Micro-Ecological Life Support System Alternative): Reinventing and compartmentalizing the Earth's food and oxygen regeneration system for long-haul space exploration missions
Hendrickx, Larissa; De Wever, Heleen; Hermans, Veronik et al

in Research in Microbiology (2006), 157

MELiSSA is a bioregenerative life support system designed by the European Space Agency (ESA) for the complete recycling of gas, liquid and solid wastes during long distance space exploration. The system ... [more ▼]

MELiSSA is a bioregenerative life support system designed by the European Space Agency (ESA) for the complete recycling of gas, liquid and solid wastes during long distance space exploration. The system uses the combined activity of different living organisms: microbial cultures in bioreactors, a plant compartment and a human crew. In this minireview, the development of a short-cut ecological system for the biotransformation of organic waste is discussed from a microorganism's perspective. The artificial ecological model—still in full development—that is inspired by Earth's own geomicrobiological ecosystem serves as an ideal study object on microbial ecology and will become an indispensable travel companion in manned space exploration. [less ▲]

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See detailLes "Ménines" de Vélasquez : une posture didactique
Heins, Pascal ULg

in Cramer, Evelyn; Ricker, Marie-Emilie; Souveryns, Patrick (Eds.) Didactiques de l'histoire et de l'histoire de l'art : divergences, convergences et complémentarités. 3e Journée interuniversitaire des Didactiques d'Histoire de l'Art (2006)

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See detailEvent-related brain potentials in psychopathology: Clinical and cognitive perspectives
Hansenne, Michel ULg

in Psychologica Belgica (2006), 46(1-2), 5-36

Since the discovery of the P300 component, a large number of studies have been conducted with the aim to find abnormalities of this psychophysiological marker among the main psychiatric disorders. The ... [more ▼]

Since the discovery of the P300 component, a large number of studies have been conducted with the aim to find abnormalities of this psychophysiological marker among the main psychiatric disorders. The first studies were very promising, but successive findings were rather controversial resulting in two main positions (the pros and the cons) as regard to the usefulness of P300 in clinical psychopathology. However, P300 studies provide interesting findings concerning information processing in psychopathology. Moreover, other Event-Related Potentials (ERPs), such as the Mismatch Negativity (MMN) and the Error-Related Negativity (ERN) are particularly interesting for the study of cognitive processes in psychopathology. In this review, the author will give an overview of the main findings of P300, MMN and ERN values in psychopathology from a clinical and a cognitive point of view. After a brief description of the rationale of ERPs, the findings in schizophrenia, depression, alcoholism, posttraumatic stress disorder, panic disorder, and obsessive-compulsive disorder will be sequentially reviewed. The diagnostic usefulness of P300 in psychopathology is limited, but could be increased if variables known to influence P300 amplitude or latency are controlled. Doubtless, grouping two or more different ERP components would greatly improve the usefulness of the clinical applications of brain potentials. On the other hand, a growing number of studies have provided evidence of the relevance of ERPs to investigate cognitive processes in psychopathology. [less ▲]

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See detailSuction and time effects on the behaviour of a reservoir chalk
Priol, Grégoire; De Gennaro, Vincenzo; Delage, Pierre et al

in Van Cotthem, Alain; Charlier, Robert; Thimus, Jean-François (Eds.) EUROCK 2006 - Multiphysics Coupling and Long Term Behaviour in Rock Mechanics (2006)

Oil reservoir rocks contain various immiscible fluids (oil, water and gas) and they are submitted to elevated temperatures in the oilfield. Hence, they exhibit a typical coupled behaviour where ... [more ▼]

Oil reservoir rocks contain various immiscible fluids (oil, water and gas) and they are submitted to elevated temperatures in the oilfield. Hence, they exhibit a typical coupled behaviour where multiphysics and coupled Thermo-Hydro-Mechanical aspects are predominant. This paper presents some results from researches carried out within the PASACHALK 2 European funded collaborative research. In this research dedicated to subsidence problems in the North sea Ekofisk oilfield, the behaviour of a reservoir chalk containing two immiscible fluids (an organic non polar fluid and water) is considered within the framework of the mechanics of unsaturated soils (no temperature effects considered). In order to account for the mechanical coupled effects related to the two pore fluids, the oil-water suction was considered as an independent stress variable. The paper presents some experimental results describing the combined effect of suction and time on the isotropic compression behaviour of the chalk. A viscoelastoplastic constitutive model based on one hand on the Barcelona BBM elastoplastic model for unsaturated and on the other hand on Perzina’s approach of viscous behaviour of soils is also presented and validated against experimental evidence. [less ▲]

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See detailAnalyse structurale et syntagmatique des institutions politiques
Verjans, Pierre ULg

in Cahiers de Sciences Politiques de l'ULg (2006)

L'analyse d'un système politique peut s'effectuer à l'aide d'une grille d'analyse structurale croisant les idées, les communications d'un côté et les intérêts, les actions de l'autre, ces matrices donnant ... [more ▼]

L'analyse d'un système politique peut s'effectuer à l'aide d'une grille d'analyse structurale croisant les idées, les communications d'un côté et les intérêts, les actions de l'autre, ces matrices donnant forme à des institutions politiques. Dès lors, la question politique fondamentale devient celle de la succession plutôt que celle de l'opposition, autrement dit celle des glissements syntagmatiques plutôt que celle des affrontements paradigmatiques. [less ▲]

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See detailEffect of surface preparation techniques on the cohesion of superficial concrete: comparison between jack-hammering and water-jetting
Courard, Luc ULg; Bissonnette, Benoît; Belair, Normand

in Beushausen, H.; Dehn, F.; Alexander, M. G. (Eds.) Concrete Repair, Rehabilitation and Retrofitting (2006)

The aim of concrete surface preparation is to obtain a surface with properties similar to those of the bulk concrete. Superficial concrete must be sound, dry, cohesive and contaminant-free. Particularly ... [more ▼]

The aim of concrete surface preparation is to obtain a surface with properties similar to those of the bulk concrete. Superficial concrete must be sound, dry, cohesive and contaminant-free. Particularly, the preparation must be performed in such a way that sound and homogeneous concrete is reached. The most widespread surface preparation techniques are sandblasting, jack-hammering, milling and other water hydro-jetting. Evaluation of the effect of surface preparation is often based upon surface roughness or specific sur-face. It is necessary however to investigate further within the first few centimetres from the surface to verify the concrete homogeneity and soundness. Pull-off test is a destructive method that can be useful for such evaluation, but it only gives an indication; the observation of the failure mode is more instructive. This paper summarizes the results of a microscopy investigation performed to quantify the number and length of cracks. The analysis leads to the comparison of jack-hammering and water-jetting techniques in terms of their poten-tial effect on superficial cohesion of concrete. [less ▲]

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See detailSize and structure characterization of dye flocs during chemical coagulation of Reactive Black 5 dye
Janeczko, Marta; Gaydardzhiev, Stoyan ULg

in Particle & Particle Systems Characterization (2006), 23

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See detailFréquence et importance du charriage dans les rivières du massif ardennais
Houbrechts, Geoffrey ULg; Hallot, Eric ULg; Gob, F. et al

in Géographie physique et Quaternaire (2006)

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See detailEvaluation of dispersant efficiency for aqueous alumina slurries by concurrent techniques
Gaydardzhiev, Stoyan ULg; Ay, Peter

in Journal of Dispersion Science & Technology (2006), 27(3), 413-417

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See detailJustinianus, Institutiones - Libri feudorum
Adam, Renaud ULg

in Bousmanne, Bernard; Thieffry, Sandrine; Wijsman, Hanno (Eds.) Filips de Schone (1478-1506) : schatten van de laatste hertog van Bourgondië : [tentoonstelling : Brussel, Koninklijke Bibliotheek van België, Nassaukapel, van 3 november 2006 tot 27 januari 2007] : catalogus (2006)

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See detailInhomogeneous and anisotropic deformation behavior and strain hardening of ultrafine-grained aluminium by ECAP
Poortmans, Stijn; El Houdaigui, Fouad; Habraken, Anne ULg et al

in Zhu, Y. T.; Langdon, T. G.; Horita, Z. (Eds.) et al Proceedings of the Ultrafine Grained Materials IV Conference (2006)

Hot-rolled AA1050 commercial pure aluminum was deformed by ECAP (Equal Channel Angular Pressing) at room temperature following route BC for 8 passes. Mechanical testing at room temperature on both hot ... [more ▼]

Hot-rolled AA1050 commercial pure aluminum was deformed by ECAP (Equal Channel Angular Pressing) at room temperature following route BC for 8 passes. Mechanical testing at room temperature on both hot-rolled aluminum and aluminum after ECAP consisted of uniaxial tension, axisymmetric compression and shear by torsion. The phenomenological Hill’s criterion identified from texture data accounts for the observed tension-compression asymmetry due to ECAP and predicts torsion yielding close to measurements. FE simulations of the compression tests are performed with a Hill model or a Minty micro-macro model and coupled with an isotropic Voce saturation hardening law. These simulations compute the inhomogeneous behavior due to barreling, the observed sample anisotropy and the force-displacement curve. Comparisons of numerical and experiments results provide a first identification of the hardening parameters and the friction coefficient during compression tests. [less ▲]

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See detailCalculation of the random-incidence scattering coefficients of a sine-shaped surface
Embrechts, Jean-Jacques ULg; De Geetere, L.; Vermeir, G. et al

in Acta Acustica United with Acustica (2006), 92(4, JUL-AUG), 593-603

Random-incidence scattering coefficients obtained by measurement in reverberation chambers (ISO 17497-1) for a particular sine-shaped surface are compared with theoretical results. Holford-Urusovskii's ... [more ▼]

Random-incidence scattering coefficients obtained by measurement in reverberation chambers (ISO 17497-1) for a particular sine-shaped surface are compared with theoretical results. Holford-Urusovskii's method and a hybrid plane wave decomposition - FEM method are applied to an infinite sine-shaped surface having the same profile, while the 3D BEM gives numerical results for the finite-size surface. Perfect rigidity (Neumann boundary condition) is assumed in all computations. The validity of the computations is compared and discussed with regard to the approximations involved. Finally, the measured and calculated values of the scattering coefficients are compared. A good correspondence is found, in particular concerning the overall dependence on frequency. Small deviations have however been observed, at low as well as at high frequencies. They will be explained by uncertainties in the measurements and discretisation errors in the calculations. [less ▲]

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See detailD'une étude de technique narrative aux contes de Voltaire et à l'édition des textes classiques
Tilkin, Françoise ULg

in Herman, Jan; Peckmans, Paul; Kremer, Nathalie (Eds.) Studies rond de Franse literatuur van de XVIIIe eeuw : Belgian Work in progress : Etudes de littérature française du XVIIIe siècle (2006)

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See detailEffects of a single injection of a progesterone receptor antagonist during the third month of gestation in sheep
Taverne, M. A. M.; Regeling, J. I.; Sulon, Joseph ULg et al

in Reproduction in Domestic Animals (2006), 41(4), 310

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See detailJ.B.G. d'Ansse de Villoison. De l'Hellade à la Grèce. Voyage en Grèce et au Levant (1784-1786)
Famerie, Etienne ULg

Book published by Georg Olms Verlag (2006)

Edition with commentary of the works of the French hellenist J.B.G. d'Ansse de Villoison pertaining to his travel in Greece and the Levant (1784-1786) : éditio princeps of the manuscript diary, new ... [more ▼]

Edition with commentary of the works of the French hellenist J.B.G. d'Ansse de Villoison pertaining to his travel in Greece and the Levant (1784-1786) : éditio princeps of the manuscript diary, new edition of a memoir extracted from his notebooks, preparatory notes related to a comparative survey on Ancient and Modern Greece. [less ▲]

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See detailParticle density determination of pellets and briquettes
Rabier, Fabienne; Temmerman, Michaël ULg; Böhm, Thorsten et al

in Biomass & Bioenergy (2006)

Several methods and procedures for the determination of particle density of pellets and briquettes were tested and evaluated. Round robin trials were organized involving five European laboratories, which ... [more ▼]

Several methods and procedures for the determination of particle density of pellets and briquettes were tested and evaluated. Round robin trials were organized involving five European laboratories, which measured the particle densities of 15 pellet and five briquette types. The test included stereometric methods, methods based on liquid displacement (hydrostatic and buoyancy) applying different procedures and one method based on solid displacement. From the results for both pellets and briquettes, it became clear that the application of a method based on either liquid or solid displacement (only tested on pellet samples) leads to an improved reproducibility compared to a stereometric method. For both, pellets and briquettes, the variability of measurements strongly depends on the fuel type itself. For briquettes, the three methods tested based on liquid displacement lead to similar results. A coating of the samples with paraffin did not improve the repeatability and the reproducibility. Determinations with pellets proved to be most reliable when the buoyancy method was applied using a wetting agent to reduce surface tensions without sample coating. This method gave the best values for repeatability and reproducibility, thus less replications are required to reach a given accuracy level. For wood pellets, the method based on solid displacement gave better values of repeatability, however, this instrument was tested at only one laboratory. [less ▲]

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See detailExamination of non-genetic factors affecting the growth performance of Djallonke sheep in soudanian zone at the Okpara Breeding farm of Benin
Gbangboche, A. B.; Youssao, A. K. I.; Adamou-Ndiaye, M. et al

in Tropical Animal Health and Production (2006), 38

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