References of "De Pauw, Edwin"
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See detailData quality of the serum analysis of PCDD, PCDF and PCB in the French dioxin and incinerators study
Pascal, M.; Eppe, Gauthier ULg; Zeghnoun, A. et al

in Organohalogen Compounds (2007), 69

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See detailTHE DIOXIN FUNCTION AS A USEFUL TOOL FOR ASSESSING DIOXIN LABORATORY PERFORMANCES IN PROFICIENCY TESTS
Eppe, Gauthier ULg; Van Cleuvenbergen, Rudy; Smastuen Haug, Line et al

in Organohalogen Compounds (2007)

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See detailAnalysis of furan by GC/MS
Scholl, Georges ULg; Eppe, Gauthier ULg; Scippo, Marie-Louise ULg et al

Poster (2007)

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See detailPROTEOMIC ANALYSIS OF WILD TYPE AND LUCIFERASE REPORTER HEPG2 CELLS EXPOSED TO TCDD
Lambert, Damien; Mazzucchelli, Gabriel ULg; De Pauw, Edwin ULg et al

in Organohalogen Compounds (2007), 69

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See detailCharge distribution in 3'-deoxythymidine-fullerene: Mass spectrometry, laser excitation, and computational studies
Greisch, Jean-François ULg; Weinkauf, R.; De Pauw, Edwin ULg et al

in Israel Journal of Chemistry (2007), 47(1), 25-35

Electrospray ionization of the donor-spacer-acceptor model system 3'-imino[60]fulleryl-3'-deoxythymidine molecule (FdT) produces deprotonated negatively charged species (dFdT). In this paper, we ... [more ▼]

Electrospray ionization of the donor-spacer-acceptor model system 3'-imino[60]fulleryl-3'-deoxythymidine molecule (FdT) produces deprotonated negatively charged species (dFdT). In this paper, we investigate where the negative charge is localized and whether its location can be manipulated. The fragmentation of dFdT is studied experimentally by mass spectrometry using both collisional and photoactivation. Besides fragmentation, photoexcitation of anions stored in an ion trap leads to electron photodetachment. The competition between the two channels is studied as a function of the excitation wavelength. Starting from the neutral parents, two families of dFdT molecules are computationally identified. Deprotonation takes place on the 3'-deoxythymidine (dT) subunit, either on the thymine at N3 or on the deoxyribose residue at O5'. Deprotonation in N3 leads to negatively charged molecules with an extended geometry and the excess charge largely localized on the dT. The O5'-deprotonation leads to lower-energy folded conformers stabilized by an additional bond (C-O or C-H) with the nearby C-60-N acceptor part, and the negative charge is mostly localized on the fullerene. The calculated electron detachment energies are higher for the extended N3dFdT conformers than for the O5'dFdT ones. Multiphoton photodetachment experiments at 1064 nm indicate the negative charge to be on the C-60 unit. No indication for a photoinduced charge transfer was found. In MS beside the C-60 anion a C60NH, - fragment is observed, which implies a double intramolecular H transfer. The computed energy of the corresponding dFdT, stabilized by two H-C-60 bonds, is intermediate between N3 and O5' deprotonated molecules. [less ▲]

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See detailStabilization and structure of telomeric and c-myc region intramolecular G-quadruplexes: The role of central cations and small planar ligands
Gabelica, Valérie ULg; Baker, Erin Shammel; Teulade-Fichou, Marie-Paule et al

in Journal of the American Chemical Society (2007), 129(4), 895-904

A promising approach for anticancer strategies is the stabilization of telomeric DNA into a G-quadruplex structure. To explore the intrinsic stabilization of folded G-quadruplexes, we combined ... [more ▼]

A promising approach for anticancer strategies is the stabilization of telomeric DNA into a G-quadruplex structure. To explore the intrinsic stabilization of folded G-quadruplexes, we combined electrospray ionization mass spectrometry, ion mobility spectrometry, and molecular modeling studies to study different DNA sequences known to form quadruplexes. Two telomeric DNA sequences of different lengths and two DNA sequences derived from the NHE III1 region of the c-myc oncogene (Pu22 and Pu27) were studied. NH4+ and the ligands PIPER, TMPyP4, and the three quinacridines MMQ1, MMQ3, and BOQ1 were complexed with the DNA sequences to determine their effect on the stability of the G-quadruplexes. Our results demonstrate that G-quadruplex intramolecular folds are stabilized by NH4+ cations and the ligands listed. Furthermore, the ligands can be classified according to their ability to stabilize the quadruplexes and end stacking is shown to be the dominant mode for ligand attachment. In all cases our solvent-free experimental observations and theoretical modeling reveal structures that are highly relevant to the solution-phase structures. [less ▲]

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See detailBase-dependent electron photodetachment from negatively charged DNA strands upon 260-nm laser irradiation
Gabelica, Valérie ULg; Rosu, Frédéric ULg; Tabarin, Thibault et al

in Journal of the American Chemical Society (2007), 129(15), 4706-4713

DNA multiply charged anions stored in a quadrupole ion trap undergo one-photon electron ejection (oxidation) when subjected to laser irradiation at 260 nm (4.77 eV). Electron photodetachment is likely a ... [more ▼]

DNA multiply charged anions stored in a quadrupole ion trap undergo one-photon electron ejection (oxidation) when subjected to laser irradiation at 260 nm (4.77 eV). Electron photodetachment is likely a fast process, given that photodetachment is able to compete with internal conversion or radiative relaxation to the ground state. The DNA [6-mer](3-) ions studied here show a marked sequence dependence of electron photodetachment yield. Remarkably, the photodetachment yield (dG(6) > dA(6) > dC(6) > dT(6)) is inversely correlated with the base ionization potentials (G < A < C < T). Sequences with guanine runs show increased photodetachment yield as the number of guanine increases, in line with the fact that positive holes are the most stable in guanine runs. This correlation between photodetachment yield and the stability of the base radical may be explained by tunneling of the electron through the repulsive Coulomb barrier. Theoretical calculations on dinucleotide monophosphates show that the HOMO and HOMO-1 orbitals are localized on the bases. The wavelength dependence of electron detachment yield was studied for dG(6)(3-). Maximum electron photodetachment is observed in the wavelength range corresponding to base absorption (260-270 nm). This demonstrates the feasibility of gas-phase UV spectroscopy on large DNA anions. The calculations and the wavelength dependence suggest that the electron photodetachment is initiated at the bases and not at the phosphates. This also indicates that, although direct photodetachment could also occur, autodetachment from excited states, presumably corresponding to base excitation, is the dominant process at 260 nm. Excited-state dynamics of large DNA strands still remains largely unexplored, and photo-oxidation studies on trapped DNA multiply charged anions can help in bridging the gap between gas-phase studies on isolated bases or base pairs and solution-phase studies on full DNA strands. [less ▲]

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See detailElectron photodetachment dissociation of DNA anions with covalently or noncovalently bound chromophores
Gabelica, Valérie ULg; Rosu, Frédéric ULg; De Pauw, Edwin ULg et al

in Journal of the American Society for Mass Spectrometry (2007), 18(11), 1990-2000

Double stranded DNA multiply charged anions coupled to chromophores were subjected to UV-Vis photoactivation. in a quadrupole ion trap mass spectrometer. The chromophores included noncovalently bound ... [more ▼]

Double stranded DNA multiply charged anions coupled to chromophores were subjected to UV-Vis photoactivation. in a quadrupole ion trap mass spectrometer. The chromophores included noncovalently bound minor groove binders (activated in the near UV), noncovalently bound intercalators (activated with visible light), and covalently linked fluorophores and quenchers (activated at their maximum absorption wavelength). We found that the activation of only chromophores having long fluorescence lifetimes did result in efficient electron photodetachment from the DNA complexes. In the case of ethidium-dsDNA complex excited at 500 nm, photodetachment is a multiphoton process. The MS3 fragmentation of radicals produced by photodetachment at lambda = 260 nm (DNA excitation) and by photodetachment at lambda > 300 nm (chromophore excitation) were compared. The radicals keep no memory of the way they were produced. A weakly bound noncovalent ligand (m-amsacrine) allowed probing experimentally that a fraction of the electronic internal energy was converted into vibrational internal energy. This fragmentation channel was used to demonstrate that excitation of the quencher DABSYL resulted in internal conversion, unlike the fluorophore 6-FAM. Altogether, photodetachment of the DNA complexes upon chromophore excitation can be interpreted by the following mechanism: (1) ligands with sufficiently long excited-state lifetime undergo resonant two-photon excitation to reach the level of the DNA excited states, then (2) the excited-state must be coupled to the DNA excited states for photodetachment to occur. Our experiments also pave the way towards photodissociation probes of biomolecule conformation in the gas-phase by Forster resonance energy transfer (FRET). [less ▲]

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See detailLigand binding mode to duplex and triplex DNA assessed by combining electrospray tandem mass spectrometry and molecular modeling
Rosu, Frédéric ULg; Nguyen, Chi-Hung; De Pauw, Edwin ULg et al

in Journal of the American Society for Mass Spectrometry (2007), 18(6), 1052-1062

In this paper, we report the analysis of seven benzopyridoindole and benzopyridoquinoxaline drugs binding to different duplex DNA and triple helical DNA, using an approach combining electrospray ... [more ▼]

In this paper, we report the analysis of seven benzopyridoindole and benzopyridoquinoxaline drugs binding to different duplex DNA and triple helical DNA, using an approach combining electrospray ionization mass spectrometry (ESI-MS), tandem mass spectrometry (MS/MS), and molecular modeling. The ligands were ranked according to the collision energy (CE(50)) necessary to dissociate 50% of the complex with the duplex or the triplex in tandem MS. To determine the probable ligand binding site and binding mode, molecular modeling was used to calculate relative ligand binding energies in different binding sites and binding modes. For duplex DNA binding, the ligand-DNA interaction energies are roughly correlated with the experimental CE(50), with the two benzopyridoindole ligands more tightly bound than the benzopyridoquinoxaline ligands. There is, however, no marked AT versus GC base preference in binding, as supported both by the ESI-MS and the calculated ligand binding energies. Product ion spectra of the complexes with triplex DNA show only loss of neutral ligand for the benzopyridoquinoxalines, and loss of the third strand for the benzopyridoindoles, the ligand remaining on the duplex part. This indicates a higher binding energy of the benzopyridoindoles, and also shows that the ligands interact with the triplex via the duplex. The ranking of the ligand interaction energies compared with the CE(50) values obtained by MS/MS on the complexes with the triplex clearly indicates that the ligands intercalate via the minor groove of the Watson-Crick duplex. Regarding triplex versus duplex selectivity, our experiments have demonstrated that the most selective drugs for triplex share the same heteroaromatic core. [less ▲]

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See detailImpact of iron and steel industry and waste incinerators on human exposure to dioxins, PCBs, and heavy metals: results of a cross-sectional study in Belgium.
Fierens, Sebastien; Mairesse, Helene; Heilier, Jean-Francois et al

in Journal of Toxicology and Environmental Health. Part A (2007), 70(3-4), 222-6

We evaluated the impact of two iron and steel plants and two municipal solid waste incinerators (MSWI) in Wallonia (Belgium) on the exposure of residents to dioxins, polychlorinated biphenyls (PCBs), and ... [more ▼]

We evaluated the impact of two iron and steel plants and two municipal solid waste incinerators (MSWI) in Wallonia (Belgium) on the exposure of residents to dioxins, polychlorinated biphenyls (PCBs), and heavy metals. In total, 142 volunteers living around these facilities were recruited and compared with 63 referents from a rural area with no industrial source of pollution. Information about smoking habits, dietary habits, anthropometric characteristics, residential history, and health status was obtained from a self-administered questionnaire. The volunteers provided blood under fasting conditions in order to evaluate the body burden of dioxins (17 polychlorinated dibenzo-p-dioxins/dibenzofurans [PCDD/Fs] congeners) and PCBs. Samples of blood and urine were also taken for the determination of cadmium, mercury, and lead. After adjustment for covariates, concentrations of cadmium, mercury, and lead in urine or blood were not increased in subjects living in the vicinity of MSWIs or sinter plants by comparison with referents. Residents around the sinter plants and the MSWI located in the industrial area had concentrations of dioxins and PCBs in serum similar to that of referents. By contrast, subjects living in the vicinity of the MSWI in the rural area showed significantly higher serum levels of dioxins (geometric mean, 38 vs. 24 pg TEQ/g fat) and coplanar PCBs (geometric mean, 10.8 vs. 7.0 pg TEQ/g fat). Although age-adjusted dioxin levels in referents did not vary with local animal fat consumption, concentrations of dioxins in subjects living around the incinerators correlated positively with their intake of local animal fat, with almost a doubling in subjects with the highest fat intake. These results indicate that dioxins and coplanar PCBs emitted by MSWIs can indeed accumulate in the body of residents who regularly consume animal products of local origin. [less ▲]

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See detailMethodologies for Measurement of Dioxins in Food
Focant, Jean-François ULg; Eppe, Gauthier ULg; Scippo, Marie-Louise ULg et al

in van Peteghem; de Saeger; Daeseleire (Eds.) Platform for Scientific Concertation: Food Safety (2007)

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See detailDevelopment of an absolute quantification method targeting growth hormone biomarkers using liquid chromatography coupled to isotope dilution mass spectrometry.
Kirsch, Stéphanie ULg; Widart, Joëlle ULg; Louette, Joel et al

in Journal of Chromatography. A (2007), 1153(1-2), 300-6

A method to perform absolute quantification of two biomarkers (IGF-1 and IGFBP-3) of growth hormone abuse has been developed. Isotope dilution is used with synthetically labelled peptides as internal ... [more ▼]

A method to perform absolute quantification of two biomarkers (IGF-1 and IGFBP-3) of growth hormone abuse has been developed. Isotope dilution is used with synthetically labelled peptides as internal standards. Peptide selection and multiple reaction monitoring design are discussed. A simple sample preparation based on the reduction and alkylation of cysteine residues followed by tryptic digestion provides a sufficient digestion of proteins. Serum samples fortified with increasing amounts of target proteins are analysed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) on a triple quadrupole mass spectrometer. Specificity is ensured by the selection of sequences with no homology in BLAST, as well as retention time deviation check, and ion ratio monitoring. Linearity is studied in terms of calibration curves. These curves for IGFBP-3 and IGF-1 are generated with mean slopes of 0.055 and 0.065, intercepts of 0.107 and -0.011, and with coefficients of correlation of 0.95 and 0.98, respectively. These curves result from the addition of proteins to the serum. Risks of variations related to potential matrix effects are therefore reduced, as well as probable variations related to the digestion steps. The working concentration ranges are 4-10 ng/microl for IGFBP-3 and 2-8 ng/microl for IGF-1. Preliminary data regarding repeatability show that relative standard deviations (RSDs) range between 13 and 32% for IGFBP-3 and between 7 and 29% for IGF-1. [less ▲]

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See detailVALAPODYN: Validated Predictive Dynamic Model of Complex Intracellular Pathways Related to Cell Death and Survival
Depaulis, Antoine; Vafiadaki, Elizabeth; Jackers, Pascale ULg et al

in European Journal of Human Genetics (2007), 15(Suppl. 1),

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See detailDépérissement de nos abeilles?
Nguyen, Bach Kim ULg; Widart, Joëlle ULg; De Pauw, Edwin ULg et al

Article for general public (2007)

Detailed reference viewed: 53 (15 ULg)