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See detailThe exocellular β-lactamase of Streptomyces albus G. Purification, properties and comparison with the exocellular DD-carboxypeptidase
Duez, Colette ULg; Frère, Jean-Marie ULg; Klein, Daniel et al

in Biochemical Journal (1981), 193(1), 75-82

The exocellular β-lactamase of Streptomyces albus G has been purified to near protein homogeneity. It consists of one single polypeptide chain of mol.wt. 30 000-31 000, has a rather low isoelectric point ... [more ▼]

The exocellular β-lactamase of Streptomyces albus G has been purified to near protein homogeneity. It consists of one single polypeptide chain of mol.wt. 30 000-31 000, has a rather low isoelectric point (at pH 6.0) and contains less lysine (2.1%) and more half-cystine residues than most β-lactamases from other Gram-positive bacteria. Penicillins are much better substrates than ∆3-cephalosporins; the catalytic-centre activity of good penicillin substrates is 333-500s-1. The exocellular, mol.wt. 17000 DD-carboxypeptidase of S. albus G [previously purified to protein homogeneity; Duez, Frère, Geurts, Ghuysen, Dierickx & Delcambe (1978) Biochem. J. 175, 793-800] behaves as an exceedingly poor β-lactamase, hydrolysing benzylpenicillin into benzylpenicilloate 5 × 10-6-fold less rapidly than does the exocellular β-lactamase. To all appearances, the β-lactamase has no bivalent cation requirement whereas, as shown elsewhere [Dideberg, Charlier, Dupont, Vermeire, Frère & Ghuysen (1980) FEBS Lett. 117, 212-214, and Dideberg, Joris, Frère, Ghuysen, Weber, Robaye, Delbrouck & Roelands (1980) FEBS Lett. 117, 215-218], the DD-carboxypeptidase possesses one essential Zn2+ ion per molecule. Peptide 'mapping' and immunological studies suggest that the two Streptomyces enzymes probably have very different structural and mechanistic properties. [less ▲]

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See detailExocellular β-lactamases of Streptomyces albus G and strains R39 and K11
Johnson, Kenneth; Dusart, Jean; Campbell, James N. et al

in Antimicrobial Agents and Chemotherapy (1973), 3(2), 289-298

The beta-lactamases excreted by the highly benzylpenicillin-susceptible Streptomyces strain R39 and the highly benzylpenicillin-resistant Streptomyces albus G were isolated and purified. Neither beta ... [more ▼]

The beta-lactamases excreted by the highly benzylpenicillin-susceptible Streptomyces strain R39 and the highly benzylpenicillin-resistant Streptomyces albus G were isolated and purified. Neither beta-lactamase exhibited dd-carboxypeptidase activity. Both were anionic at pH 8.3, did not require metal ions, and were not sensitive to iodine, but were inhibited by Cu(2+) and readily inactivated by heat. p-Chloromercuribenzoate, iodoacetate, p-aminobenzoate, and substrates and inhibitors of dd-carboxypeptidase had no effect on beta-lactamase activity. The K(m) and V(max) values for beta-lactamase activity were studied with 6-aminopenicillanic acid and with various penicillins and cephalosporins. The beta-lactamase from the related strain K11 of Streptomyces, which is intermediate in its susceptibility to benzylpenicillin, was partially purified, and its activity was compared on the various substrates. [less ▲]

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See detailExogenous glucose oxidation during exercise in relation to the power output.
Pirnay, Freddy ULg; Scheen, André ULg; Gautier, J. F. et al

in International Journal of Sports Medicine (1995), 16(7), 456-60

In order to study the influence of the power output on the oxidation rate of exogenous glucose and on the contribution of the various substrates to the energy demand, we combined the use of artificially ... [more ▼]

In order to study the influence of the power output on the oxidation rate of exogenous glucose and on the contribution of the various substrates to the energy demand, we combined the use of artificially enriched 13C-glucose with classical indirect calorimetry during uphill treadmill exercise. Six young male healthy subjects underwent three exercise bouts, in a randomized order and at least two weeks apart, at a low (45% VO2max, 1822 +/- 194 ml O2/min for 4 hours), moderate (60% VO2max, 2582 +/- 226 ml O2/min for 3 hours), and high intensity (75% VO2max, 3036 +/- 287 ml O2/min for 2 hours). After 10 min of exercise, each subject ingested 100 g of artificially 13C-labelled glucose dissolved in 400 ml of water. Over the four hours of the exercise at 45% VO2max, the amount of exogenous glucose oxidized was 89.5 +/- 5.9 g from the 100 g ingested. In all exercise bouts, the oxidation of exogenous glucose already began during the first 30 min after ingestion and peaked at 120 min. The maximum oxidation rates averaged 0.64 +/- 0.07, 0.75 +/- 0.04, and 0.63 +/- 0.08 g/min, and the mean amounts of exogenous glucose oxidized over the first two hours averaged 51.7 +/- 8.0, 61.5 +/- 6.6 and 50.9 +/- 8.45 g, at 45, 60 and 75% VO2max respectively. The contribution of the oxidation of exogenous glucose to the total energy supply progressively decreased when the power output increased, from 19.6 to 12.2%. In the meantime, the contribution of total carbohydrates (exogenous+endogenous) progressively increased from 55.1 to 77.8% while the contribution of lipids decreased from 35.5 to 16.6%. In conclusion, exogenous glucose ingested during exercise is largely oxidized and strongly contributes to the energy supply. The oxidation rate first increases with the power output, but levels off or even decreases at high intensity exercise. [less ▲]

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See detailExogenous prostaglandin administration and pseudo-bartter syndrome
Battisti, Oreste ULg; Langhendries, J. P.; Thiry, E. et al

in European Journal of Pediatrics (1989), 149

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See detailDie exokrine Pankreasfunktion beim kranken Pferd
Sandersen, Charlotte ULg; Serteyn, Didier ULg; Grulke, Sigrid ULg

in Vervuert; Achenbach; Gäbel (Eds.) et al LBH, Proccedings 5. Leipziger Tieraerzte Tag (2009)

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See detail"Exolysosomes", Enzyme-Containing Vesicles in the Ecdysial Space of Molting Crabs
Compère, Philippe ULg; Bouchtia, Hicham; Thiry, Marc ULg et al

in Journal of Structural Biology (1997), 119(3), 247-59

Free vesicle-like bodies (VLBs) present in the ecdysial space of cuticle regions undergoing degradation during preecdysis of the Atlantic shore crab Carcinus maenas have been interpreted either as ... [more ▼]

Free vesicle-like bodies (VLBs) present in the ecdysial space of cuticle regions undergoing degradation during preecdysis of the Atlantic shore crab Carcinus maenas have been interpreted either as infectious organisms or as secretion structures associated with degradation of the old cuticle. Ultrastructural, cytochemical, and immunocytological investigations were performed to test these hypotheses and to see whether VLBs are peculiar to this crab species. Similar VLBs were systematically found in two other preecdysial crabs, Cancer pagurus and Macropipus puber. In Car, maenas, they originate during early premolt inside Golgi buddings and are often gathered into large vacuoles in epidermal cells. The histochemical azo-dye technique and a cerium-based cytochemical method revealed acid phosphatase activity in both the ecdysial space and the VLBs, while Feulgen's method and immunocytological labeling always failed to reveal any DNA or RNA in either the ecdysial space or the VLBs. We conclude that VLBs are not infectious organisms but "extracellular" cuticle-degrading organelles of lysosomal origin and propose to coin them "exolysosomes." [less ▲]

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See detailExome sequencing in Brown-Vialetto-van Laere syndrome.
Johnson, Janel O; Gibbs, J Raphael; Van Maldergem, Lionel ULg et al

in American Journal of Human Genetics (2010), 87(4), 567-9569-70

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See detailExome sequencing of tumors: relevance in copy-number alteration (CNA) analysis and fixed tissue samples.
Wenric, Stéphane ULg; JOSSE, Claire ULg; Fasquelle, Corinne ULg et al

Poster (2013, March 15)

Genomic DNA has been extracted from both cryopreserved and formalin-fixed paraffin-embedded forms of 2 different tumor samples (triple negative, and Her2+). Exome sequencing has been performed on all 4 ... [more ▼]

Genomic DNA has been extracted from both cryopreserved and formalin-fixed paraffin-embedded forms of 2 different tumor samples (triple negative, and Her2+). Exome sequencing has been performed on all 4 forms, as well as SNP and CNA detection. A comparison of the various metrics and results related to the sequencing, mapping, and variants detection has been done, outlining what can, and can’t be done with exome data sequenced from cryopreserved and FFPE tissue. [less ▲]

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See detailExonic deletions in AUTS2 cause a syndromic form of intellectual disability and suggest a critical role for the C terminus.
Beunders, Gea; Voorhoeve, Els; Golzio, Christelle et al

in American journal of human genetics (2013), 92(2), 210-20

Genomic rearrangements involving AUTS2 (7q11.22) are associated with autism and intellectual disability (ID), although evidence for causality is limited. By combining the results of diagnostic testing of ... [more ▼]

Genomic rearrangements involving AUTS2 (7q11.22) are associated with autism and intellectual disability (ID), although evidence for causality is limited. By combining the results of diagnostic testing of 49,684 individuals, we identified 24 microdeletions that affect at least one exon of AUTS2, as well as one translocation and one inversion each with a breakpoint within the AUTS2 locus. Comparison of 17 well-characterized individuals enabled identification of a variable syndromic phenotype including ID, autism, short stature, microcephaly, cerebral palsy, and facial dysmorphisms. The dysmorphic features were more pronounced in persons with 3'AUTS2 deletions. This part of the gene is shown to encode a C-terminal isoform (with an alternative transcription start site) expressed in the human brain. Consistent with our genetic data, suppression of auts2 in zebrafish embryos caused microcephaly that could be rescued by either the full-length or the C-terminal isoform of AUTS2. Our observations demonstrate a causal role of AUTS2 in neurocognitive disorders, establish a hitherto unappreciated syndromic phenotype at this locus, and show how transcriptional complexity can underpin human pathology. The zebrafish model provides a valuable tool for investigating the etiology of AUTS2 syndrome and facilitating gene-function analysis in the future. [less ▲]

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See detailExophthalmos and strabismus associated with a frontal mucocele in a 6-month-old puppy
Monclin, Sébastien ULg; Saulnier-Troff F.; Bolen, Géraldine ULg et al

Poster (2008, May)

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See detailExoplanet Characterization and the Search for Life
Kasting, James; Traub, W.; Roberge, A. et al

E-print/Working paper (2009)

Over 300 extrasolar planets (exoplanets) have been detected orbiting nearby stars. We now hope to conduct a census of all planets around nearby stars and to characterize their atmospheres and surfaces ... [more ▼]

Over 300 extrasolar planets (exoplanets) have been detected orbiting nearby stars. We now hope to conduct a census of all planets around nearby stars and to characterize their atmospheres and surfaces with spectroscopy. Rocky planets within their star's habitable zones have the highest priority, as these have the potential to harbor life. Our science goal is to find and characterize all nearby exoplanets; this requires that we measure the mass, orbit, and spectroscopic signature of each one at visible and infrared wavelengths. The techniques for doing this are at hand today. Within the decade we could answer long-standing questions about the evolution and nature of other planetary systems, and we could search for clues as to whether life exists elsewhere in our galactic neighborhood. [less ▲]

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See detailExoplanet discoveries with the CoRoT space observatory
Lammer, H.; Dvorak, R.; Deleuil, M. et al

in Solar System Research (2010), 44

The CoRoT space observatory is a project which is led by the French space agency CNES and leading space research institutes in Austria, Brazil, Belgium, Germany and Spain and also the European Space ... [more ▼]

The CoRoT space observatory is a project which is led by the French space agency CNES and leading space research institutes in Austria, Brazil, Belgium, Germany and Spain and also the European Space Agency ESA. CoRoT observed since its launch in December 27, 2006 about 100 000 stars for the exoplanet channel, during 150 days uninterrupted high-precision photometry. Since the The CoRoT-team has several exoplanet candidates which are currently analyzed under its study, we report here the discoveries of nine exoplanets which were observed by CoRoT. Discovered exoplanets such as CoRoT-3b populate the brown dwarf desert and close the gap of measured physical properties between usual gas giants and very low mass stars. CoRoT discoveries extended the known range of planet masses down to about 4.8 Earth-masses (CoRoT-7b) and up to 21 Jupiter masses (CoRoT-3b), the radii to about 1.68 × 0.09 R [SUB]Earth[/SUB] (CoRoT-7b) and up to the most inflated hot Jupiter with 1.49 × 0.09 R [SUB]Earth[/SUB] found so far (CoRoT-1b), and the transiting exoplanet with the longest period of 95.274 days (CoRoT-9b). Giant exoplanets have been detected at low metallicity, rapidly rotating and active, spotted stars. Two CoRoT planets have host stars with the lowest content of heavy elements known to show a transit hinting towards a different planethost-star-metallicity relation then the one found by radial-velocity search programs. Finally the properties of the CoRoT-7b prove that rocky planets with a density close to Earth exist outside the Solar System. Finally the detection of the secondary transit of CoRoT-1b at a sensitivity level of 10[SUP]-5[/SUP] and the very clear detection of the "super-Earth" CoRoT-7b at 3.5 × 10[SUP]-4[/SUP] relative flux are promising evidence that the space observatory is being able to detect even smaller exoplanets with the size of the Earth. [less ▲]

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See detailExoplanet imaging with mid-infrared vector vortex coronagraphs: design, manufacture, validation and first light of the annular groove phase mask
Delacroix, Christian ULg

Doctoral thesis (2013)

During the past twenty years, detections of extrasolar planets have flourished and grown expo- nentially, reaching almost 900 confirmed exoplanets so far. This number is doubling every two or three years ... [more ▼]

During the past twenty years, detections of extrasolar planets have flourished and grown expo- nentially, reaching almost 900 confirmed exoplanets so far. This number is doubling every two or three years. The most recent discoveries made by the Kepler mission have revealed two Earth- size exoplanets orbiting the same star, and fulfilling all the required conditions to be habitable. Imaging techniques have also come a long way. Since the first direct detection in 2004, some stunning exoplanet pictures have been captured at the telescope under special circumstances of moderate contrast and/or angular separation, thanks to the advent and continuous improvement of adaptive optics systems and data reduction methods. In this broad context, the need for high contrast imaging techniques with very small inner working angles has never been so strong. Coro- nagraphy has a key role to play in order to provide the means necessary for imaging Earth-size planets, and try to answer the recurring question of the possible presence of life outside the solar system. The present thesis is dedicated to the development of the annular groove phase mask (AGPM), a specific type of broadband vector vortex coronagraph based on subwavelength gratings. Consid- ered for several years as one of the best solutions for building high-performance mid-infrared coron- agraphs with small inner working angles, the AGPM has never been validated up to now. Although various fabrication processes are available, depending on the substrates and micro-lithography techniques considered, they often face extremely challenging constraints. In the present work, we explored the feasibility of achromatic micro-components made out of subwavelength gratings, for which two technological solutions are followed: quartz and diamond. As we focussed on the diamond option, its unique material properties making it a prime candidate for mid-infrared ap- plications, we managed to develop mid-infrared broadband half-wave plates, ideally optimized to enable the manufacturing of charge-2 vortices. Following this success, we continued our devel- opments leading to the fabrication of several AGPMs for two astronomic windows, the L and N bands, and we successfully validated several L-band AGPMs on a coronagraphic test bench at the Observatoire de Paris. In the last chapter, we expose the recent installation of our components on three world-class infrared cameras, VISIR and NACO at the Very Large Telescope in Chile, and LMIRCam at the Large Binocular Telescope in Arizona. We conclude with the very first on-sky results of both N-band and L-band AGPMs, and the discovery and successful imaging of a faint stellar companion at two beamwidths from an F-type star. [less ▲]

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See detailExopolysaccharides production by selected bacteria
Valepyn, Emmanuel ULg; Paquot, Michel ULg; Nys, Joël

Poster (2011, August)

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See detailExosites Mediate The Anti-Inflammatory Effects Of A Multifunctional Serpin From The Saliva Of The Tick Ixodes Ricinus
Prevot, Pp.; Beschin, A.; Lins, Laurence ULg et al

in Febs Journal (2009), 276(12),

Serine protease inhibitors (serpins) are a structurally related but functionally diverse family of ubiquitous proteins. We previously described Ixodes ricinus immunosuppressor (Iris) as a serpin from the ... [more ▼]

Serine protease inhibitors (serpins) are a structurally related but functionally diverse family of ubiquitous proteins. We previously described Ixodes ricinus immunosuppressor (Iris) as a serpin from the saliva of the tick I. ricinus displaying high affinity for human leukocyte elastase. Iris also displays pleotropic effects because it interferes with both the immune response and hemostasis of the host. It thus inhibits lymphocyte proliferation and the secretion of interferon-gamma or tumor necrosis factor-alpha by peripheral blood mononuclear cells, and also platelet adhesion, coagulation and fibrinolysis. Its ability to interfere with coagulation and fibrinolysis, but not platelet adhesion, depends on the integrity of its antiproteolytic reactive center loop domain. Here, we dissect the mechanisms underlying the interaction of recombinant Iris with peripheral blood mononuclear cells. We show that Iris binds to monocytes/macrophages and inhibits their ability to secrete tumor necrosis factor-alpha. Recombinant Iris also has a protective role in endotoxemic shock. The anti-inflammatory ability of Iris does not depend on its antiprotease activity. Moreover, we pinpoint the exosites involved in this activity. [less ▲]

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