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See detailCharacterization and regulation of the angiotensin II type-1 receptor (binding and mRNA) in human adrenal fasciculata-reticularis cells.
Naville, D.; LEBRETHON, Marie-Christine ULg; Kermabon, A. Y. et al

in FEBS letters (1993), 321(2-3), 184-8

The classical concept of human adrenal physiology indicates that only glomerulosa cells are the target of A-II. Herein, we demonstrated that cultured human adrenal fasciculata-reticularis cells were also ... [more ▼]

The classical concept of human adrenal physiology indicates that only glomerulosa cells are the target of A-II. Herein, we demonstrated that cultured human adrenal fasciculata-reticularis cells were also responsive to this hormone. Indeed, these cells contained high affinity (Kd = 0.9-1.1 nM) and low capacity (8,000-13,000 sites/cell) A-II receptors, and more than 95% of them were of the type-1. These AT1 receptors are functional since A-II was able to increase cortisol production after 48 h of treatment. These effects were inhibited by losartan, an AT1 antagonist, but not by CGP42112A, an AT2 antagonist. The expression of the type-1 A-II receptor mRNA was detected in the whole adrenal in both adult and fetus, and in cultured human adrenal fasciculata-reticularis cells. In these cells A-II negatively regulated AT1 receptor mRNA, and this effect was also mediated through the AT1 receptor subtype. [less ▲]

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See detailCharacterization and regulation of the hb9/mnx1 beta-cell progenitor specific enhancer in zebrafish.
Arkhipova, Valeriya; Wendik, Bjorn; Devos, Nathalie et al

in Developmental Biology (2012), 365(1), 290-302

Differentiation of insulin producing beta-cells is a genetically well defined process that involves functions of various conserved transcription factors. Still, the transcriptional mechanisms underlying ... [more ▼]

Differentiation of insulin producing beta-cells is a genetically well defined process that involves functions of various conserved transcription factors. Still, the transcriptional mechanisms underlying specification and determination of beta-cell fate are poorly defined. Here we provide the description of a beta-cell progenitor specific enhancer as a model to study initial steps of beta-cell differentiation. We show that evolutionary non-conserved upstream sequences of the zebrafish hb9 gene are required and sufficient for regulating expression in beta-cells prior to the onset of insulin expression. This enhancer contains binding sites for paired-box transcription factors and two E-boxes that in EMSA studies show interaction with Pax6b and NeuroD, respectively. We show that Pax6b is a potent activator of endodermal hb9 expression and that this activation depends on the beta-cell enhancer. Using genetic approaches we show that pax6b is crucial for maintenance but not induction of pancreatic hb9 transcription. As loss of Pax6b or Hb9 independently results in the loss of insulin expression, the data reveal a novel cross-talk between the two essential regulators of early beta-cell differentiation. While we find that the known pancreatic E-box binding proteins NeuroD and Ngn3 are not required for hb9 expression we also show that removal of both E-boxes selectively eliminates pancreatic specific reporter expression. The data provide evidence for an Ngn3 independent pathway of beta-cell specification that requires function of currently not specified E-box binding factors. [less ▲]

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See detailCharacterization and tissue-specific expression of two lepidopteran farnesyl diphosphate synthase homologs: Implications for the biosynthesis of ethyl-substituted juvenile hormones
Cusson, M.; Beliveau, C.; Sen, Se. et al

in Proteins-Structure Function and Bioinformatics (2006), 65(3), 742758

The sesquiterpenoid juvenile hormone (JH) regulates insect development and reproduction. Most insects produce only one chemical form of JH, but the Lepidoptera produce four derivatives featuring ethyl ... [more ▼]

The sesquiterpenoid juvenile hormone (JH) regulates insect development and reproduction. Most insects produce only one chemical form of JH, but the Lepidoptera produce four derivatives featuring ethyl branches. The biogenesis of these JHs requires the synthesis of ethyl-substituted farnesyl diphosphate (FPP) by FPP synthase (FPPS). To determine if there exist more than one lepidopteran FPPS, and whether one FPPS homolog is better adapted for binding the builder ethyl-branched substrates/products, we cloned three lepidopteran FPPS cDNAs, two from Choristoneura fumiferana and one from Pseudaletia unipuncta. Amino acid sequence comparisons among these and other eukaryotic FPPSs led to the recognition of two lepidopteran FPPS types. Type-I FPPSs display unique active site substitutions, including several in and near the first aspartaterich motif, whereas type-II proteins have a more "conventional" catalytic cavity. In a yeast assay, a Drosophila FPPS clone provided full complementation of an FPPS mutation, but lepidopteran FPPS clones of either type yielded only partial complementation, suggesting unusual catalytic features and/or requirements of these enzymes. Although a structural analysis of lepidopteran FPPS active sites suggested that type-I enzymes are better suited than type-II for generating ethyl-substituted products, a quantitative real-time PCR assessment of their relative abundance in insect tissues indicated that type-I expression is ubiquitous whereas that of type-II is essentially confined to the JH-producing glands, where its transcripts are ∼20 times more abundant than those of type-I. These results suggest that type-II FPPS plays a leading role in lepidopteran JH biosynthesis in spite of its apparently more conventional catalytic cavity [less ▲]

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See detailCharacterization and transfection experiments of polyplexes targeting HDAC7
Frère, Antoine ULg; Kawalec, Michal; Collard, Laurence ULg et al

Poster (2012, October 22)

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See detailCharacterization and Tumorigenicity of Spheroids Composed of Pigmented or Non Pigmented B16 Melanoma Cells
Coucke, P. H.; De Pauw-Gillet, Marie-Claire ULg; Bonjean, K. A. et al

in In Vivo (Athens, Greece) (1994), 8(3, May-Jun), 333-8

A parental line of mouse B16 melanoma cells (B16) and two derived cloned lines, either pigmented (B16P) or non pigmented (B16NP), were cultured in vitro as spheroids. After 48 hrs, the pigmented cells ... [more ▼]

A parental line of mouse B16 melanoma cells (B16) and two derived cloned lines, either pigmented (B16P) or non pigmented (B16NP), were cultured in vitro as spheroids. After 48 hrs, the pigmented cells (B16, B16P) formed smaller and looser aggregates, with higher rates of cell proliferation and lower amounts of extracellular matrix as compared to B16NP spheroids. The three lines were more tumorigenic when inoculated subcutaneously as spheroids than as isolated cells. Furthermore, B16P or B16 spheroids developed richly vascularized subcutaneous tumors and metastases more rapidly than B16NP aggregates. After intravenous injection of spheroids, the measurement with an image analyzer of the area of sections in lung colonies indicated that B16P colonies were larger and more numerous than those induced by B16NP cells. [less ▲]

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See detailCharacterization at nanometric scale of the interaction between fluoroquinolones (ciprofloxacin) and membrane lipids
Bensikaddour, Helmet; Fa, Nathalie; Deleu, Magali ULg et al

Poster (2006)

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See detailCHARACTERIZATION OF 3 LABDANE DITERPENES FROM AFRAMOMUM-ALBOVIOLACEUM
Marlier, Michel; LEGUELLEC, G.; Lognay, Georges ULg et al

in Planta Medica (1993), 59(5), 455-457

Two labdane diterpenes were isolated from the seeds and the rhizomes of Aframomum alboviolaceum (Ridley) K. Schum (Zingiberaceae) and identified by GC-MS, H-1-, and C-13-NMR as (E)-labda-8(17),12-diene-15 ... [more ▼]

Two labdane diterpenes were isolated from the seeds and the rhizomes of Aframomum alboviolaceum (Ridley) K. Schum (Zingiberaceae) and identified by GC-MS, H-1-, and C-13-NMR as (E)-labda-8(17),12-diene-15,16-dial (1) and (E)-8beta,17-epoxylabd-12-ene-15,16-dial (2). A third minor compound could be the methyl (E)-14xi,15-epoxylabd-8(17), 12-dien-16-oate. The simultaneous occurrence of these three molecules has been mentioned only in one other species of the same genus, Aframomum daniellii (1). [less ▲]

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See detailCharacterization of 4-(2-hydroxyphenyl)-1-[2 '-[N-(2 ''-pyridinyl)-p-fluorobenzamido]ethyl]piperazine (p-DMPPF) as a new potent 5-HT1A antagonist
Defraiteur, Caroline ULg; Plenevaux, Alain ULg; Scuvée-Moreau, Jacqueline ULg et al

in British Journal of Pharmacology (2007), 152(6), 952-958

Background and purpose: The identification of potent and selective radioligands for the mapping of 5-HT receptors is interesting both for clinical and experimental research. The aim of this study was to ... [more ▼]

Background and purpose: The identification of potent and selective radioligands for the mapping of 5-HT receptors is interesting both for clinical and experimental research. The aim of this study was to compare the potency of a new putative 5-HT1A receptor antagonist, p-DMPPF, (4-(2-hydroxyphenyl)-1-[2'-[N-(2''-pyridinyl)-p-fluorobenzamido]-ethyl] piperazine) with that of the well-known 5-HT1A antagonists, WAY-100635(N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]-ethyl]-N-(2-pyridinyl) cyclohexanecarboxamide) and its fluorobenzoyl analogue, p-MPPF (4-(2-methoxyphenyl)-1-[2'-[N-(2''-pyridinyl)p-fluorobenzamido] ethyl] piperazine). Experimental approach: Single cell extracellular recordings of dorsal raphe (DR) neurones were performed in rat brain slices. The potency of each compound at antagonizing the effect of the 5-HT1A agonist, 8-OH-DPAT [8-hydroxy-2-(di-npropylamino)tetraline], was quantified using the Schild equation. The pharmacological profile of p-DMPPF was defined using competition binding assays. Key results: Consistently with a 5-HT1A receptor antagonist profile, incubation of slices with an equimolar (10 nM) concentration of each compound markedly reduced the inhibitory effect of 8-OH-DPAT on the firing rate of DR neurones, causing a significant rightward shift in its concentration-response curve. The rank order of potency of the antagonists was WAY-100635 > p-DMPPF >= p-MPPF. The sensitivity of DR neurones to the inhibitory effect of 8-OH-DPAT was found to be heterogeneous. The binding experiments demonstrated that p-DMPPF is highly selective for 5-HT1A receptors, with a K-i value of 7 nM on these receptors. Conclusions and implications: The potency of the new compound, p-DMPPF, as a 5-HT1A antagonist is similar to that of p-MPPF in our electrophysiological assay. Its selectivity towards 5-HT1A receptors makes it a good candidate for clinical development. [less ▲]

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See detailCharacterization of a cavern conduit system in Vietnam by time series correlation, cross-spectrum and wavelet analyses
Tam, V. T.; De Smedt, F.; Batelaan, Okke et al

in Hydrological Sciences Journal = Journal des Sciences Hydrologiques (2004), 49(5), 879-900

Time series analyses are applied to characterize the transient flow regimes of the Nam La cavern conduit, northwest Vietnam. The conduit transforms the input signal to an output signal, and the degree of ... [more ▼]

Time series analyses are applied to characterize the transient flow regimes of the Nam La cavern conduit, northwest Vietnam. The conduit transforms the input signal to an output signal, and the degree of transformation provides information on the nature of the flow system. The input for the analysis is net precipitation and the flow hydrograph at the cave entrance, while the output series is the flow hydrograph at the resurgence. Cross-correlation and cross-spectrum analysis are used to investigate the stationarity and linearity of the input-output transformation of the system, resulting in hydrodynamic properties such as system memory, response time, and mean delay between input and output. It is shown that during high flow periods, the flow in the conduit is pressurized. Consequently, the linear input-output assumption holds only for low flows. To highlight the hydrodynamics of the cavern conduit for the high flow periods, wavelet spectrum and wavelet cross-spectrum analyses are applied. [less ▲]

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See detailCharacterization of a cDNA encoding the mitochondrial alternative oxidase (AOX) in Chlamydomonas reinhardtii and assays of AOX inactivation by the antisense strategy
Dinant, Monique; Baurain, Denis ULg; Matagne, René-Fernand ULg

in Møller, I. M.; Gardeström, P.; Glimelius, K. (Eds.) et al Plant Mitochondria: From Gene to Function (1998)

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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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