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See detailCharacterization of a chimaeric plasminogen activator obtained by insertion of the second kringle structure of tissue-type plasminogen activator (amino acids 173 through 262) between residues Asp130 and Ser139 of urokinase-type plasminogen activator.
Lijnen, H. R.; Pierard, Luc ULg; Reff, M. E. et al

in Thrombosis research (1988), 52(5), 431-41

A chimaeric recombinant plasminogen activator (rscu-PA- K2) obtained by insertion of the second kringle (K2) of tissue-type plasminogen activator (t-PA) (amino acids 173-262) between residues Asp130 and ... [more ▼]

A chimaeric recombinant plasminogen activator (rscu-PA- K2) obtained by insertion of the second kringle (K2) of tissue-type plasminogen activator (t-PA) (amino acids 173-262) between residues Asp130 and Ser139 of single chain urokinase-type plasminogen activator (scu-PA) was purified from the conditioned medium of mouse myeloma cells transfected with the previously described plasmid pULB9137 (Pierard et al., J. Biol. Chem. 262, 11771-11778, 1987). Approximately 22 micrograms of purified protein was obtained per liter of conditioned medium with a yield of approximately 25 percent. On sodium dodecylsulfate gel electrophoresis under reducing conditions, rscu-PA- K2 migrated with an apparent Mr of 65,000. Plasmin caused a time- and concentration-dependent conversion to an amidolytically active two chain derivative (rtcu-PA- K2) with a specific activity of 45,000 IU/mg. Both rscu-PA- K2 and rtcu-PA- K2 activated plasminogen directly with Km = 2.0 microM and k2 = 0.00063 s-1 and Km = 100 microM and k2 = 4.1 s-1 respectively. rscu-PA- K2 did not bind extensively to fibrin. It caused concentration-dependent lysis of 125I-fibrin-labeled plasma clots immersed in human plasma with a comparable specific activity and fibrin-specificity as rscu-PA. It is concluded that insertion in scu-PA of the second kringle of t-PA, which is believed to be involved in its fibrin affinity, does not significantly alter the enzymatic properties of scu-PA, but does not confer marked fibrin-affinity to the molecule. [less ▲]

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See detailCharacterization of a family harboring a novel LHBéta subunit mutation associated with hypogonadism
Burlacu, M. C.; Daly, Adrian ULg; Salvi, R. et al

in 17th Meeting of the Belgian Endocrine Society : Bruxelles, 25 novembre 2007 (2007, November)

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See detailCHARACTERIZATION OF A HIGHLY PHOTOACTIVE MOLECULAR SEMICONDUCTOR - OXOTITANIUM PHTHALOCYANINE
Ghosez, Philippe ULg; COTE, R.; GASTONGUAY, L. et al

in Chemistry of Materials (1993), 5(10), 1581-1590

Oxotitanium phthalocyanine (OTiPc) thin films have been sublimed at various thicknesses on SnO2 and glass substrates. The morphology, crystallinity, and photoelectrochemical activity of the films have ... [more ▼]

Oxotitanium phthalocyanine (OTiPc) thin films have been sublimed at various thicknesses on SnO2 and glass substrates. The morphology, crystallinity, and photoelectrochemical activity of the films have been studied. It was found that the physical and photoelectrochemical properties of the films are greatly influenced by the temperature reached by the substrate during the sublimation. Below 80-degrees-C, amorphous films are obtained while the films are partially crystalline when the substrate is allowed to reach about 140-degrees-C. Amorphous films are made of tightly packed aggregates of circular section while partially crystalline films consists of platelets. All films are porous and permeable to the I3-/I- redox system. The dominant polymorph in partially crystalline films is not the same for all film thicknesses. It is phase IV OTiPc (as deduced by electron diffraction) for films thinner than about 2000 angstrom. On the other hand, for films thicker than about 8000 angstrom, phase I OTiPc becomes the dominant polymorph (as deduced by X-ray diffraction). It is replaced by phase II for 20 000-angstrom-thick films of OTiPc. Partially crystalline films are the only ones to absorb in the near-infrared (NIR) region. This typical absorption is going along with an improvement of the photoactivity of the films. In partially crystalline films, energy is transferred from the amorphous to the crystalline regions where most of the charges are generated. Quantum yields for electron collection per incident photon may reach over 25% in short circuit conditions, at 850 nm, the Q-band absorption maximum for 8000-angstrom-thick films. Those films are phase I OTiPc. Under 35 MW CM-2 polychromatic illumination, the same films are characterized by short circuit photocurrents of 1.5 mA cm-2. A NIR absorbance is an important factor required to obtain a high photoactivity, but it is not the only one. Interaction of OTiPc with oxygen at the purification level of the crude material is very important as well. [less ▲]

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See detailCharacterization of a knock-down mutant deficient for isocitrate lyase in Chlamydomonas reinhardtii
Remacle, Claire ULg

in Microorganisms for bio-fuel production from sunlight, ESF conference (2011)

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See detailCharacterization of a mechanical motion amplifier applied to a MEMS accelerometer
Zeimpekis, Ioannis; Sari, Ibrahim; Kraft, Michaël ULg

in Journal of Microelectromechanical Systems (2012), 21(5), 1032-1042

In this paper, a mechanical amplification concept for microelectromechanical systems (MEMS) physical sensors is proposed with the aim to improve their sensitivity. The scheme is implemented using a system ... [more ▼]

In this paper, a mechanical amplification concept for microelectromechanical systems (MEMS) physical sensors is proposed with the aim to improve their sensitivity. The scheme is implemented using a system of micromachined levers (microlevers) as a deflection amplifying mechanism. The effectiveness of the mechanism is demonstrated for a capacitive accelerometer. A proof-of-concept single-axis mechanically amplified accelerometer with an amplification factor of 40 has been designed, simulated, and fabricated, and results from its evaluation are presented in this paper. The sensor's amplified output has a sensitivity of 2.39 V/g using an open-loop capacitive pick-off circuit based on charge amplifiers. Experimental results show that the addition of the mechanical amplifier does not alter the noise floor of the sensor. The measured natural frequency of the first mode of the sensor is at 734 Hz, and the full-scale measurement range is up to 7 g with a maximum nonlinearity of 2\%. It is shown, through comparison with a conventional design, that the mechanically amplified accelerometer provides higher deflection without sacrificing bandwidth. [less ▲]

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See detailCharacterization of a new efflux pump, MexGHI-OpmD, from Pseudomonas aeruginosa that confers resistance to vanadium.
Aendekerk, Severine; Ghysels, Bart ULg; Cornelis, Pierre et al

in Microbiology (Reading, England) (2002), 148(Pt 8), 2371-81

Vanadium has an antibacterial activity against Pseudomonas aeruginosa, especially under conditions of iron limitation. Some degree of resistance to V is inducible by prior exposure to the metal. One ... [more ▼]

Vanadium has an antibacterial activity against Pseudomonas aeruginosa, especially under conditions of iron limitation. Some degree of resistance to V is inducible by prior exposure to the metal. One mutant (VS1) with a higher sensitivity to V was obtained by transposon mutagenesis of P. aeruginosa PA 59.20, a clinical isolate. This mutant had an insertion in a non-coding region, upstream of a cluster of four genes. Three of them show similarities to genes corresponding to known P. aeruginosa antibiotic efflux systems, including an efflux protein, a membrane fusion protein and an outer-membrane porin. This cluster was named mexGHI-opmD. By allelic exchange, three mutants, ncr (for non-coding region), mexI and opmD were constructed in P. aeruginosa PAO1. Next to V sensitivity, the ncr, mexI and opmD mutants also showed reduced production of elastase, rhamnolipids, pyocyanine, pyoverdine and had reduced swarming motility, phenotypes that are known to be regulated by quorum sensing. All wild-type phenotypes, including growth in the presence of V, were restored by complementation with the complete cluster. The production of N-acyl-homoserine lactones (AHLs) was detected using the Chromobacter violaceum bioassay. Total extracts from the three mutants failed to induce the production of violacein by C. violaceum, although AHLs were detected by TLC and C. violaceum overlay. Violacein production was restored by complementation with mexGHI-opmD. The opmD mutant grew very slowly in LB or CAA medium, indicating that OpmD has an important physiological function for the cell. In conclusion, it is believed that the MexGHI-OpmD pump is probably involved in AHL homeostasis in P. aeruginosa. [less ▲]

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See detailCharacterization of a new potential virulence factor of Microsporum canis, the secreted subtilisin Sub6
Mathy, Anne ULg; Baldo, Aline ULg; Salamin, K. et al

in Mycoses (2011), 54(suppl 2), 112-113

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See detailCharacterization of a novel aphid prenyltransferase displaying dual geranyl/farnesyl diphosphate synthase activity
Vandermoten, Sophie ULg; Charloteaux, Benoît ULg; Santini, S. et al

in FEBS Letters (2008), 582(16), 19281934

We report on the cDNA cloning and characterization of a novel short-chain isoprenyl diphosphate synthase from the aphid Myzus persicae. Of the three IPPS cDNAs we cloned, two yielded prenyltransferase ... [more ▼]

We report on the cDNA cloning and characterization of a novel short-chain isoprenyl diphosphate synthase from the aphid Myzus persicae. Of the three IPPS cDNAs we cloned, two yielded prenyltransferase activity following expression in Escherichia coli; these cDNAs encode identical proteins except for the presence, in one of them, of an N-terminal mitochondrial targeting peptide. Although the aphid enzyme was predicted to be a farnesyl diphosphate synthase by BLASTP analysis, rMpIPPS, when isopentenyl diphosphate and dimethylallyl diphosphate are supplied as substrates, typically generated geranyl diphosphate (C10) as its main product, along with significant quantities of farnesyl diphosphate (C15). Analysis of an MpIPPS homology model pointed to substitutions that could confer GPP/FPP synthase activity to the aphid enzyme. [less ▲]

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See detailCharacterization of a novel chitinase from a moderately halophilic bacterium, Virgibacillus marismortui strain M3-23
Essghaier, Badiaa; Hedi, Abdeljabbar; Bajji, Mohammed et al

in Annals of Microbiology (2012), 62(2), 835-841

A new chitinase produced by the moderately halophilic bacterium Virgibacillus marismortui strain M3- 23 was identified and characterized. Distinguishable characteristics of high activity and stability at ... [more ▼]

A new chitinase produced by the moderately halophilic bacterium Virgibacillus marismortui strain M3- 23 was identified and characterized. Distinguishable characteristics of high activity and stability at different pH, temperatures and salinity of M3-23 chitinase are reported. Analysis of the catalytic domain sequence from the enzyme highlighted its relationship to glycosyl hydrolase family 18. Comparison of the deduced chitinase sequence from strain M3-23 to known chitinases from Bacillus species showed low similarity (82%), suggested its novelty. This is the first report of the characterization of chitinase from the species V. marismortui. The halo- and thermo-tolerant nature of the chitinolytic enzyme allows its potential use in agricultural and industrial applications. [less ▲]

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See detailCharacterization of a novel circo-like virus in Aedes vexans mosquitoes from Germany: evidence for a new genus within the Circoviridae family.
Garigliany, Mutien-Marie ULg; Borstler, Jessica; Jost, Hanna et al

in The Journal of general virology (2014)

During the last decades, metagenomic studies expanded the numbers of newly described, often unclassified, viruses within the Circoviridae family. Using broad-spectrum circo-/cyclovirus PCRs, we ... [more ▼]

During the last decades, metagenomic studies expanded the numbers of newly described, often unclassified, viruses within the Circoviridae family. Using broad-spectrum circo-/cyclovirus PCRs, we characterized a novel circo-like virus in Aedes vexans mosquitoes from Germany whose main putative open reading frames (ORFs) shared very low amino acid identity with those of previously characterized circo-/cycloviruses. Phylogenetic and genetic distance analysis revealed that this new virus species defines, with previously described mosquito- and bat feces-derived circo-like viruses, a different genus, tentatively called "krikovirus", within Circoviridae. We further demonstrated that viruses of the putative krikovirus genus all share a genomic organization which is unique among Circoviridae. Further investigations are needed to determine the host range, tissue tropism and transmission route(s). This report increases the current knowledge of the genetic diversity and evolution of the members of the Circoviridae family. [less ▲]

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See detailCharacterization of a novel extended-spectrum TEM-type beta-lactamase, TEM-164, in a clinical strain of Klebsiella pneumoniae in Tunisia.
Ben Achour, Nahed; Mercuri, Paola ULg; Ben Moussa, Mohamed et al

in Microbial drug resistance (Larchmont, N.Y.) (2009), 15(3), 195-9

Klebsiella pneumoniae ML1708 exhibited a multiresistance phenotype, including resistance to all beta-lactams tested, chloramphenicol, ciprofloxacin, nalidixic acid, tetracycline, and streptomycin. The ... [more ▼]

Klebsiella pneumoniae ML1708 exhibited a multiresistance phenotype, including resistance to all beta-lactams tested, chloramphenicol, ciprofloxacin, nalidixic acid, tetracycline, and streptomycin. The double-disk synergy test was positive. ML1708 harbored a 50 kb conjugative plasmid that encoded a beta-lactamase of pI 5.5. The corresponding bla gene was identified by polymerase chain reaction and sequencing as a bla(TEM) gene. The deduced protein sequence revealed a new variant of TEM-1 beta-lactamase designated TEM-164. TEM-164 contains the unusual following mutations: L40V and I279T. These modifications may result in a change of the pI to 5.5 and hydrolyze cefotaxime and ceftazidime. [less ▲]

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See detailCharacterization of a novel freshwater gigartinalean red alga from Belize, with description of Sterrocladia belizeana sp. nov
Sherwood, AR; Necchi Jr, O; Carlile, AL et al

in Phycologia (2012), 51(6), 627-635

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See detailCharacterization of a novel IMP-28 metallo-β-lactamase from a Spanish Klebsiella oxytoca clinical isolate
Pérez-Llarena, FJ; Fernández, A; Zamorano, L et al

in Antimicrobial Agents and Chemotherapy (2012), 56(8), 4540-3

An isolate of Klebsiella oxytoca carrying a novel IMP metallo-β-lactamase was discovered in Madrid, Spain. The bla(IMP-28) gene is part of a chromosomally located class I integron. The IMP-28 k(cat)/K(m ... [more ▼]

An isolate of Klebsiella oxytoca carrying a novel IMP metallo-β-lactamase was discovered in Madrid, Spain. The bla(IMP-28) gene is part of a chromosomally located class I integron. The IMP-28 k(cat)/K(m) values for ampicillin, ceftazidime, and cefepime and, to a lesser extent, imipenem and meropenem, are clearly lower than those of IMP-1. The His306Gln mutation may induce important modifications of the L3 loop and thus of substrate accessibility and hydrolysis and be the main reason for this behavior. [less ▲]

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See detailCHARACTERIZATION OF A NOVEL RADIOTRACER TARGETING SYNAPTIC VESICLE PROTEIN 2A (SV2A)
Warnock, Geoffrey ULg; Aerts, Joël ULg; Bahri, Mohamed Ali ULg et al

Poster (2012, September)

Synaptic vesicle protein 2A (SV2A) has been identified as the binding site of the antiepileptic levetiracetam (Keppra) [1]. SV2 proteins are critical for proper nervous system function and have been ... [more ▼]

Synaptic vesicle protein 2A (SV2A) has been identified as the binding site of the antiepileptic levetiracetam (Keppra) [1]. SV2 proteins are critical for proper nervous system function and have been demonstrated to be involved in vesicle trafficking. Their implication in epilepsy makes them an interesting therapeutic target, and the widespread distribution of SV2A in particular may provide an opportunity to develop a PET-based measure of neuronal function in brain diseases. [18F]UCB-H is a fluorine-18 radiolabelled PET imaging agent with a nanomolar affinity for the human SV2A protein. Preclinical PET studies in rodents were carried out using male SD rats, imaged under isoflurane anaesthesia in a Siemens Concorde Focus 120 microPET scanner. Arterial input function was measured using an arteriovenous shunt method and beta microprobe system. [18F]UCB-H was injected IV (3.8 ± 0.54 mCi bolus, specific activity 8.5 ± 0.86 Ci/Emol immediately after synthesis) and dynamic PET data acquired in list mode for 90 min. Images were reconstructed using filtered back projection with correction for all physical effects except scatter. These scans revealed high uptake of [18F]UCB-H in brain and spinal cord, matching the expected homogeneous distribution of SV2A in the rodent brain [2]. Notably, the kinetics of [18F]UCB-H uptake in the brain were fast, peaking at up to 30 % ID/cm3 before a rapid decline. Metabolism of [18F]UCB-H in vivo followed a typical pattern of rapid initial metabolism followed by a reducing rate of metabolism over time, with less than 20% of the activity in plasma attributable to the parent compound after 30 minutes, and was highly reproducible between subjects. One major metabolite was identified. The uptake of [18F]UCB-H in the brain over time was well fitted by a classical 1-tissue compartment model. Mean parameter estimates (mean ± SD, n=7, whole brain VOI) were K1: 3.58 ± 0.65 ml/cm3/min, k2: 0.21 ± 0.03 min-1, Vt: 17.21 ± 2.52 ml/cm3. Uptake of [18F]UCB-H was blocked by pretreatment with brivaracetam (21 mg/kg IV, 10 min prior to [18F]UCB-H), a recently described high affinity SV2A ligand with a 20-fold higher affinity for SV2A than levetiracetam [3]. In contrast, pretreatment with ucb-100230-1, a diastereoisomer of brivaracetam with 3200-fold lower affinity for SV2A [3], had no clear effect of the brain uptake of [18F]UCB-H. Our results indicate that [18F]UCB-H is a suitable radiotracer for the quantification of SV2A proteins in vivo and for estimating target occupancy of drugs targeting SV2A. This is the first PET tracer for in vivo quantification of SV2A. The necessary steps for implementation of [18F]UCB-H production under GMP conditions have been completed and first in human studies are planned. References [1] Lynch, B.A. et al. (2004) PNAS 101(26):9861-6. [2] Janz, R. & Sudhof, T.C. (1999) Neuroscience 94(4):1279-1290.[3] Gillard, M. et al. (2011) Eur J Pharmacol 664:36-44. [less ▲]

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See detailCharacterization of a population of the Harlequin crab, Lissocarcinus orbicularis Dana, 1852, an obligate symbiont of holothuroids, in Toliara bay (Madagascar)
Caulier, Guillaume; Parmentier, Eric ULg; Lepoint, Gilles ULg et al

in Zoosymposia (2012), 7

Harlequin crabs, Lissocarcinus orbicularis, are commensals found on the integument and in the buccal/cloacal cavity of several species of holothuroids. The population of these crabs was investigated on ... [more ▼]

Harlequin crabs, Lissocarcinus orbicularis, are commensals found on the integument and in the buccal/cloacal cavity of several species of holothuroids. The population of these crabs was investigated on holothuroids of the barrier reef of Toliara (South-West of Madagascar) from 2002 to 2008. Seventeen holothuroid species were observed and eight were crab hosts. There is generally one adult crab or a heterosexual pair per infested holothuroid but up to ten juveniles were recorded on a Thelenota ananas. Carapace length of the observed L. orbicularis was from 0.3 to 1.4 cm from the tip of the rostrum to the end of the cephalothorax, with a mean length of 0.85 cm. L. orbicularis is characterized by a weak sexual dimorphism (females are bigger than males) and the presence of pereiopods morphologically adapted to fixation on the host integument. Gravid females were observed at each month of the survey indicating that the crab reproduces all the year. Considering our results and personal observations, we also discuss the monogamy mating system of the Harlequin crab. [less ▲]

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