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See detailPeut-on utiliser l'auto-estimation à l'école ? Qu'en aurait dit DESCARTES ?
Leclercq, Dieudonné ULg

in Enjeux : Revue de Formation Continuée et de Didactique du Français (1991), 22

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See detailPeut-on vivre avec le ragondin ? Les représentations sociales reliées à un animal envahissant
Mougenot, Catherine ULg; Roussel, Laurence

in Natures Sciences Sociétés (2006), 14(suppl.), 22-31

Aujourd'hui les introductions d'espèces exotiques, souvent qualifiées d'espèces invasives, sont vues comme une menace pour les écosystèmes. En menant une enquête sur les représentations liées au ragondin ... [more ▼]

Aujourd'hui les introductions d'espèces exotiques, souvent qualifiées d'espèces invasives, sont vues comme une menace pour les écosystèmes. En menant une enquête sur les représentations liées au ragondin, introduit en Europe depuis près de 100 ans, nous avons découvert que cet animal a aussi une nature domestique, sauvage et nuisible. De notre étude, il ressort également que ces représentations sont liées aux actions menées contre lui. En effet elles supposent des formes d'organisation et des choix techniques qui ont des impacts sur la nature et les hommes eux-mêmes. De là découle qu'il n'y a pas de clivages simples entre humains et espèces animales, mais de nombreuses lignes de partage, fortement contextualisées, inscrites dans des lieux et des moments. Les représentations de la nature sont aussi liées à celles des territoires, aux risques sanitaires acceptables et au profil des acteurs qui doivent mener les actions de lutte. On comprend alors qu'il est bien difficile aujourd'hui d'aligner tous ces points de manière satisfaisante. [less ▲]

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See detailPeuvent ils s'adapter ?
Libois, Roland ULg

Learning material (1983)

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See detailPex, Analytical Tools For Pdb Files. I. Gf-Pex: Basic File To Describe A Protein
Thomas, Annick ULg; Bouffioux, O.; Geeurickx, D. et al

in Proteins-Structure Function and Genetics (2001), 43(1), 28-36

Pex are created to extract numeric and string descriptions of protein structures from PDB files. This concerns covalent bond lengths and angles, secondary structures, residues in interaction, H-bond ... [more ▼]

Pex are created to extract numeric and string descriptions of protein structures from PDB files. This concerns covalent bond lengths and angles, secondary structures, residues in interaction, H-bond lengths and geometry, etc. Several kinds of Pex are generated: (1) general feature (GF-Pex); (2) H-bond (H-Pex); and (3) accessible surface (AS-Pex) and force potential (FP-Pex). We describe the general principles of Pex and detail the GF-Pex files. Using the GF-Pex of 131 proteins, we analyze the mean residue frequencies, the straight phi/psi distribution and the major kinds of secondary structures in proteins. Thomas et al. (this issue) analyzes the main chain H-bonds in those proteins. The GF-Pex and H-Pex files of the 131 proteins can be downloaded from the CBMN site (http://www.fsagx.ac.be/bp/). [less ▲]

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See detailPex, Analytical Tools For Pdb Files. II. H-Pex: Noncanonical H-Bonds In Alpha-Helices
Thomas, Annick ULg; Benhabiles, N.; Meurisse, R. et al

in Proteins-Structure Function and Genetics (2001), 43(1), 37-44

We use the H-Pex (Thomas et al., this issue) to analyze the main chain interactions in 131 proteins. In antiparallel beta-sheets, the geometry of the N...O bond is: median N...O distances, 2.9 SA, C==O ... [more ▼]

We use the H-Pex (Thomas et al., this issue) to analyze the main chain interactions in 131 proteins. In antiparallel beta-sheets, the geometry of the N...O bond is: median N...O distances, 2.9 SA, C==O...N angles at 154 degrees and the C alpha--C==O...H angles are dispersed around 3 degrees. In some instances, the other side of the C==O axis is occupied by a HC alpha. As recently supported by Vargas et al. (J Am Chem Soc 2000;122:4750-4755) C alpha H...O and NH...O could cooperate to sheet stability. In alpha-helices, the main chain C==O interact with the NH of their n + 4 neighbor on one side, and with a C beta H or C gamma H on the other side. The median O...N distance (3.0 A) and C==N angle (147 degrees) suggest a canonical H-bond, but the C alpha--C==O...H dihedral angle invalidates this option, since the hydrogen attacks the oxygen at 122 degrees, i.e., between the sp(2) and pi orbitals. This supports that the H-bond is noncanonical. In many instances, the C gamma H or the C beta H of the n + 4 residue stands opposite to the NH with respect to the oxygen. Therefore, we propose that, in alpha-helices, the C gamma H or C beta H and the NH of the n + 4 residue hold the oxygen like an electrostatic pincher. [less ▲]

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See detailPeyer's Patches in Murine Aids: Dissociation between Lymphoproliferation and Anergy
Colombi, S.; Moutschen, Michel ULg; de Leval, Laurence ULg et al

in Scandinavian Journal of Immunology (1997), 45(2), 175-81

RadLV-Rs infection induces a murine immunodeficiency syndrome associated with a dramatic enlargement of spleen and lymph nodes. Surprisingly, the lymphoproliferation excludes thymus and Peyer's patches ... [more ▼]

RadLV-Rs infection induces a murine immunodeficiency syndrome associated with a dramatic enlargement of spleen and lymph nodes. Surprisingly, the lymphoproliferation excludes thymus and Peyer's patches (PP). To understand the cellular interactions underlying lymphoproliferation further, the authors investigated the fate of PP in RadLV-Rs infected mice. The atrophy of PP was mostly due to the depletion of B cells, while the proportion of CD4+ and CD8+ T cells was increased. Nevertheless, B cell phenotype was modified with the emergence of lymphocytes with a low expression of B220 in infected PP. T cells characterized by a memory/activated phenotype in control PP did not undergo phenotypical changes after viral infection (i.e. regarding Thy-1 and CD44 expression). Despite the absence of lymphoproliferation, PP T and B cells displayed altered responses to mitogens in vitro. Finally, alterations of the expression of adhesion molecules and vascular addressins could not explain the atrophy of PP by a reduced homing to this lymphoid site. B cells and T cells from normal PP are clearly different from lymph nodes (LN) lymphocytes. The authors propose that the particular functional state which characterizes PP lymphocytes influences the B cell/T cell crosstalk necessary for RadLV-Rs-induced lymphoproliferation. [less ▲]

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See detailPGPR-induced systemic resistance: activity of amphiphilic elicitors and structural analogues on different plant species
Jourdan, Emmanuel ULg; Ongena, MARC ULg; Adam, Akram et al

in Bulletin OILB/SROP = IOBC/WPRS Bulletin (2007), 30

Some non pathogenic microorganisms can induce disease resistance mechanisms expressed systemically in the host plant thereby rendering it less susceptible to further attack by pathogens. In this study, we ... [more ▼]

Some non pathogenic microorganisms can induce disease resistance mechanisms expressed systemically in the host plant thereby rendering it less susceptible to further attack by pathogens. In this study, we have investigated the role of bacterial compounds as elicitors of the induced systemic resistance. Lipopeptides, especially surfactin and fengycin, produced by Bacillus subtilis strains are able to stimulate bean and tomato plants and decrease the impact of subsequent pathogen infection. Preliminary experiments on tobacco cells showed that surfactine induces some modifications in the phenylpropanoid pathway. Amphiphilic properties of lipopeptides and NABD, the elicitor isolated from Pseudomonas putida strain BTP1, could be responsible for their activities on plant cells [less ▲]

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See detailpH and redox responsive hydrogels and nanogels made from poly(2-ethyl-2-oxazoline)
Legros, Camille ULg; De Pauw-Gillet, Marie-Claire ULg; Tam, Kam Chiu et al

in Polymer Chemistry (2013)

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See detailThe pH dependence of rat liver RNA polymerases I and II.
Bull, P.; Martial, Joseph ULg; Téllez, R. et al

in Archivos de Biologia y Medicina Experimentales (1980), (13), 265-269

The effect of pH on the stability and activity of rat liver RNA polymerases I (A) and II (B) has been studied. Both enzymes are irreversibly inactivated in buffer solutions below pH 5.0. Km values of the ... [more ▼]

The effect of pH on the stability and activity of rat liver RNA polymerases I (A) and II (B) has been studied. Both enzymes are irreversibly inactivated in buffer solutions below pH 5.0. Km values of the two enzymes are constant between pH 6.5 and 8.7 but a two -to three- fold increase is observed between pH 8.7 and 9.7. The Vmax versus pH profiles are bell-shaped curves indicating the participation of two ionizing groups with apparent pKa values of 6.5 and 9.8 for enzyme I and 6.7 and 9.9 for enzyme II. Both enzymes are inactivated by photooxidation in the presence of Rose Bengal. It is suggested that the above pKa corresponds to the imidazole of a histidine residue and a amino group of a lysine residue. [less ▲]

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See detailThe pH dependence of the active-site serine DD-peptidase of Streptomyces R61
Varetto, Louis; Frère, Jean-Marie ULg; Nguyen-Distèche, Martine ULg et al

in European Journal of Biochemistry (1987), 162(3), 525-531

Titration of the active-site serine DD-peptidase of Streptomyces R61 shows that formation of acyl enzyme during hydrolysis of the substrate Ac2-L-Lys-D-Ala-D-Ala and enzyme inactivation by the beta-lactam ... [more ▼]

Titration of the active-site serine DD-peptidase of Streptomyces R61 shows that formation of acyl enzyme during hydrolysis of the substrate Ac2-L-Lys-D-Ala-D-Ala and enzyme inactivation by the beta-lactam compounds benzylpenicillin, N-acetylampicillin and ampicillin relies on the acidic form of an enzyme's group of pK approximately equal to 9.5. It is proposed that protonation of a lysine epsilon-amino group facilitates initial binding by charge pairing with the free carboxylate of the substrate and the beta-lactam molecules. Lowering the pH from 7 to 5 has no effect on the second-order rate constant of enzyme acylation by benzylpenicillin and N-acetylampicillin but results in a decreased rate constant of acylation by ampicillin and Ac2-L-Lys-D-Ala-D-Ala. Protonation of the side-chain amino group of ampicillin and a decreased efficacy of the initial binding of the peptide to the enzyme seem to be responsible for the observed effects. Whatever the molecule bound to the enzyme, there is no sign for the active involvement of an enzyme's histidine residue of pK 6.5-7.0 in the hydrolysis pathway. [less ▲]

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See detailpH Dependence of the morphology of aqueous micelles formed by polystyrene-block-poly(2-vinylpyridine)-block-poly(ethylene oxide) copolymers
Gohy, Jean-François; Willet, Nicolas ULg; Varshney, Sunil K et al

in e-Polymers (2002), (35), 1-10

The morphology of micelles formed by two polystyrene-block-poly(2-vinylpyridine)- block-poly(ethylene oxide) (PS-b-P2VP-b-PEO) copolymers was studied in water by dynamic light scattering and transmission ... [more ▼]

The morphology of micelles formed by two polystyrene-block-poly(2-vinylpyridine)- block-poly(ethylene oxide) (PS-b-P2VP-b-PEO) copolymers was studied in water by dynamic light scattering and transmission electron microscopy. Spherical micelles were observed that consist of a PS core, a P2VP shell and a PEO corona. The characteristic size of core, shell and corona depends on the copolymer composition. An important increase in micellar size occurs at pH < 5 as a result of P2VP block protonation. The reversibility of this pH effect depends on copolymer composition, too. The conformation of the PEO block plays an important role in this pH driven morphological transition. [less ▲]

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See detailPh Ib/II study of BKM120 plus trastuzumab in patients with trastuzumab-resistant HER2+ advanced breast cancer
Pistilli, Barbara; Urruticoechea, Ander; Chan Stephen et al

in Annals of Oncology (2012), 23(supplément 9), 116

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See detailpH-Dependence of the morphology of micelles formed by poly(2-vinylpyridine)-block-poly(ethylene oxide) copolymers in water
Gohy, Jean-François; Mores, Sandrine; Varshney, Sunil K et al

in e-Polymers (2002), (21), 1-8

The morphology of micelles formed by two poly(2-vinylpyridine)-block-poly(ethylene oxide) (P2VP-b-PEO) copolymers has been studied in phosphate-buffered water by dynamic light scattering and transmission ... [more ▼]

The morphology of micelles formed by two poly(2-vinylpyridine)-block-poly(ethylene oxide) (P2VP-b-PEO) copolymers has been studied in phosphate-buffered water by dynamic light scattering and transmission electron microscopy. Spherical micelles are observed when the P2VP block is the minor component of the diblock copolymer. When P2VP dominates the composition, transition from spheres-to-rods-to-vesicles takes place in a narrow pH range that straddles the pKa of P2VP. This transition is controlled by the degree of protonation of the P2VP blocks. At high pH, the copolymer precipitates from the solution. [less ▲]

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See detailpH-dependent micellization of poly(2-vinylpyridine)-block-poly((dimethylamino) ethyl methacrylate) diblock copolymers
Gohy, Jean-François; Antoun, Sayed; Jérôme, Robert ULg

in Macromolecules (2001), 34(21), 7435-7440

A series of poly(2-vinylpyridine)-block-poly((dimethylamino)ethyl methacrylate) diblock copolymers (P2VP-b-PDMAEMA) have been synthesized by living anionic polymerization of the comonomers. Dynamic light ... [more ▼]

A series of poly(2-vinylpyridine)-block-poly((dimethylamino)ethyl methacrylate) diblock copolymers (P2VP-b-PDMAEMA) have been synthesized by living anionic polymerization of the comonomers. Dynamic light scattering (DLS) has been used to study the associative behavior of these copolymers in water as a function of copolymer composition, pH, ionic strength, and temperature. Three association regimes are observed. At low pH, loose aggregates are formed, although both the P2VP and PDMAEMA blocks are protonated. At intermediate pH, micelles are observed that consist of an uncharged hydrophobic P2VP core surrounded by a protonated PDMAEMA corona. At higher pH, the PDMAEMA corona is essentially uncharged and collapses at temperatures higher than 40 °C, which results in unstable micelles. The micelles observed by transmission electron microscopy are spherical. [less ▲]

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See detailpH-Programmable DNA Logic Arrays Powered by Modular DNAzyme Libraries
Elbaz, J.; Wang, F.; Remacle, Françoise ULg et al

in Nano Letters (2012)

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See detailPH-responsive biodegradable amphiphilic networks
Zednik, Jiri; Riva, Raphaël ULg; Lussis, Perrine ULg et al

in Polymer (2008), 49(3), 697-702

Copper-mediated azide - alkyne Huisgen's 1,3-dipolar cycloaddition is a "click" reaction that was successfully used to prepare pH-responsive, amphiphilic and biodegradable networks. Indeed, this reaction ... [more ▼]

Copper-mediated azide - alkyne Huisgen's 1,3-dipolar cycloaddition is a "click" reaction that was successfully used to prepare pH-responsive, amphiphilic and biodegradable networks. Indeed, this reaction proved to be very efficient in the "one pot" grafting of amino alkyne onto azide containing poly(epsilon-caprolactone) and the cross-linking of these chains by alpha,omega-dialkynyl poly(ethylene oxide). The pH-controlled release of guests hosted during the cross-linking step was illustrated with an entrapped model dye. [less ▲]

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See detailpH-Responsive diblock copolymers prepared by the dual initiator strategy
Bernaerts, Katrien V.; Willet, Nicolas ULg; Van Camp, Wim et al

in Macromolecules (2006), 39(11), 3760-3769

Diblock copolymers poly(tetrahydrofuran-b-tert-butyl acrylate) (PTHF-b-PtBA) and poly(tetrahydrofuranb- 1-ethoxyethyl acrylate) (PTHF-b-PEEA) were successfully synthesized by the dual initiator 4 ... [more ▼]

Diblock copolymers poly(tetrahydrofuran-b-tert-butyl acrylate) (PTHF-b-PtBA) and poly(tetrahydrofuranb- 1-ethoxyethyl acrylate) (PTHF-b-PEEA) were successfully synthesized by the dual initiator 4-hydroxybutyl-2- bromoisobutyrate (HBBIB). The isobutyrate and alcohol function of HBBIB were used for the atom transfer radical polymerization of tBA ( or EEA) and the living cationic ring-opening polymerization of THF, respectively. Hydrolysis or thermolysis of the aforementioned diblock copolymers results in amphiphilic pH-responsive copolymers PTHF-b-poly( acrylic acid) ( PTHF-b-PAA). Matrix-assisted laser desorption/ ionization time-of-flight (MALDI-TOF) and nuclear magnetic resonance spectroscopy (H-1 NMR) were used to analyze the PTHF macroinitiator, while clear evidence for the formation of well-defined block copolymer structures was obtained by 1H NMR, gel permeation chromatography (GPC), and infrared spectroscopy (FT-IR). The amorphous PtBA block in PTHF-b-PtBA resulted in a decrease of the crystallinity and the melting point of PTHF, as shown by differential scanning calorimetry (DSC). Self-assembly of PTHF-b-PAA copolymers in water into aggregates and micelles when exposed to specific pH values was confirmed by dynamic light scattering, infrared, and NMR spectroscopies. [less ▲]

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See detailpH-responsive flower-type micelles formed by a biotinylated poly(2-vinylpyridine)-block-poly(ethylene-oxide)-block-poly(ε-caprolactone) triblock copolymer
Van Butsele, Kathy ULg; Cajot, Sébastien ULg; Van Vlierberghe, Sandra et al

in Advanced Functional Materials (2009), 19(9), 1416-1425

In the present work, a method is proposed to assemble pH-responsive, flower-like micelles that can expose a targeting unit at their periphery upon a decrease in pH. The micelles are composed of a novel ... [more ▼]

In the present work, a method is proposed to assemble pH-responsive, flower-like micelles that can expose a targeting unit at their periphery upon a decrease in pH. The micelles are composed of a novel biotinylated triblock copolymer of poly(-caprolactone)-block-poly(ethylene oxide)-block-poly(2-vinylpyridine) (PCL-b-PEO-b-P2VP) and the non-biotinylated analogue. The block copolymers are synthesized by sequential anionic and ring-opening polymerization. The pH-dependent micellization behaviour in aqueous solution of the triblock copolymers developed is studied using dynamic light scattering, zeta potential, transmission electron microscopy (TEM), and fluorimetric measurements. The shielding of the biotin at neutral pH and their availability at the micelle surface upon protonation is established by TEM and surface plasmon resonance with avidin and streptavidin-coated gold surfaces. The preliminary stealthy behavior of these pH-responsive micelles is examined using the complement activation (CH50) test. [less ▲]

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