References of "De Pauw, Edwin"
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See detailNew strategy for comprehensive analysis of polybrominated diphenyl ethers, polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and polychlorinated biphenyls by gas chromatography coupled with mass spectrometry
Pirard, Catherine; De Pauw, Edwin ULg; Focant, Jean-François ULg

in Journal of Chromatography. A (2003), 998(1-2), 169-181

A strategy for determination of polybrominated diphenyl ethers, polychlorinated dibenzodioxins, polychlorinated dibenzofurans and polychlorinated biphenyls on fatty matrices has been established. After ... [more ▼]

A strategy for determination of polybrominated diphenyl ethers, polychlorinated dibenzodioxins, polychlorinated dibenzofurans and polychlorinated biphenyls on fatty matrices has been established. After extraction, the proposed method allows the purification and the fractionation of all target groups of compounds in a simple multi-step automated clean-up. Furthermore, their subsequent analysis is carried out using a single benchtop mass spectrometer, in four separate injections. Required sensitivity considering levels found in the environment is attained using electron impact ionisation followed by tandem in time mass spectrometry. The whole method has been evaluated on standard solution and quality control samples consisting of fortified beef fat. Sensitivity, selectivity, accuracy and repeatability were tested with satisfactory results. (C) 2003 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailMeasurable impact of an old MSWI on the level of dioxins in free-range chickens and eggs grown in its vicinity
Pirard, C.; Focant, Jean-François ULg; Massart, A. C. et al

in Organohalogen Compounds (2003), 60-65

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See detailLevels of selected PBDEs and PCBs in Belgian human milk
Pirard, C.; De Pauw, Edwin ULg; Focant, Jean-François ULg

in Organohalogen Compounds (2003), 61

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See detailIncreased dioxin/PCB body burden in diabetics: findings in a population-based study in Belgium
Fierens, S.; Mairesse, H.; Heilier, H. et al

in Organohalogen Compounds (2003), 60-65

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See detailLevels of PCDDs, PCDFs and PCBs in International Fast Food Samples
Focant, Jean-François ULg; Pirard, Catherine; De Pauw, Edwin ULg

in Organohalogen Compounds (2003), 60-65

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See detailInteractions of cryptolepine and neocryptolepine with unusual DNA structures
Guittat, Lionel; Alberti, Patrizia; Rosu, Frédéric ULg et al

in Biochimie (2003), 85(5), 535-547

Cryptolepine, the main alkaloid present in the roots of Cryptolepis sanguinolenta, presents a large spectrum of biological properties. It has been reported to behave like a DNA intercalator with a ... [more ▼]

Cryptolepine, the main alkaloid present in the roots of Cryptolepis sanguinolenta, presents a large spectrum of biological properties. It has been reported to behave like a DNA intercalator with a preference for GC-rich sequences. In this study, dialysis competition assay and mass spectrometry experiments were used to determine the affinity of cryptolepine and neocryptolepine for DNA structures among duplexes, triplexes, quadruplexes and single strands. Our data confirm that cryptolepine and neocryptolepine prefer GC over AT-rich duplex sequences, but also recognize triplex and quadruplex structures. These compounds are weak telomerase inhibitors and exhibit a significant preference for triplexes over quadruplexes or duplexes. (C) 2003 Editions scientifiques et medicales Elsevier SAS and Societe francaise de biochimie et biologic moleculaire. All rights reserved. [less ▲]

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See detailInfluence of response factors on determining equilibrium association constants of non-covalent complexes by electrospray ionization mass spectrometry
Gabelica, Valérie ULg; Galic, Nives; Rosu, Frédéric ULg et al

in Journal of Mass Spectrometry [=JMS] (2003), 38(5), 491-501

A method for determining the equilibrium association constant of a complexation reaction A + B <=> AB by electrospray ionization mass spectrometry is described. The method consists in measuring the ... [more ▼]

A method for determining the equilibrium association constant of a complexation reaction A + B <=> AB by electrospray ionization mass spectrometry is described. The method consists in measuring the relative intensities of the peaks corresponding to A and to AB in equimolar A–B solutions at different concentrations C0. The results are fitted by a non-linear least-squares procedure, with the two variable parameters being the equilibrium association constant Ka and a factor R, defined by I(AB)/I.A/ = R× [AB]/[A]. The factor R is the ratio between the response factors of AB and A, and corrects for the relative electrospray responses of the complex and the free substrate A, mass discrimination of instrumental origin and/or moderate in-source dissociation. The method is illustrated with the following two systems: complexes between a double-stranded 12-base pair oligonucleotide and minor groove binders, and cyclodextrin complexeswith a,!-dicarboxylic acids. For the oligonucleotide complexes, it is found that the response of the complex is not dramatically different to the response of the free oligonucleotide duplex, as the double helix conformation is disturbed by the drug only to a minor extent. In the case of cyclodextrin complexes, these complexes were found to have a much higher response than free cyclodextrin. This may be due to the fact that cyclodextrin is neutral in solution, whereas the complex is charged, but it can also stem from the fact that a significant proportion of the complex is in a non-inclusion geometry. The present method requires the exact determination of the concentrations of the reactants and is applicable to 1 : 1 complexes. [less ▲]

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See detailValidation and discussion of CALUX analysis for marine samples
Windal, Isabelle; Van Wouwe, Nathalie; Carbonnelle, Sophie et al

in Organohalogen Compounds (2003)

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See detailSelective adsorption of dioxins and PCBs from marine oils on activated carbon
De Meulenaer, Bruno; Maes, Jeroen; Van Heerswynghels, Peter et al

in Organohalogen Compounds (2003)

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See detailAnalysis of PCDD/Fs in human blood plasma using CALUX bioassay and GC-HRMS: a comparison
Van Wouwe, Nathalie; Eppe, Gauthier ULg; Xhrouet, Céline ULg et al

in Organohalogen Compounds (2003)

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See detailDioxins, furans and dioxin-like PCBs in juvenile harbour porpoises (Phocoena Phocoena) from the North sea
Beans, Cristina; Debacker, Virginie ULg; Jauniaux, Thierry ULg et al

in Organohalogen Compounds (2003)

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See detailThermometer ions for matrix-enhanced laser desorption/ionization internal energy calibration
Greisch, Jean-François ULg; Gabelica, Valérie ULg; Remacle, Françoise ULg et al

in Rapid Communications in Mass Spectrometry : RCM (2003), 17(16), 1847-1854

This work describes a method to use relative fragmentation yields to characterize the internal energy distribution of ions produced by matrix-enhanced laser desorption/ionization mass spectrometry (MELDI ... [more ▼]

This work describes a method to use relative fragmentation yields to characterize the internal energy distribution of ions produced by matrix-enhanced laser desorption/ionization mass spectrometry (MELDI-MS, see: Wright LG, Cooks RG, Wood KL. Biomed. Mass Spectrom. 1985; 12:153162). Assuming that the fragmentation proceeds statistically and that the collisions in the source lead to a Boltzmann-like distribution of the internal energy, a characteristic parameter, the effective temperature, is introduced to describe the internal energy distribution of the ions observed. The hypotheses, advantages and drawbacks of the implementation of the method that uses substituted benzylpyridinium salts as thermometer ions are discussed. Use is made of two matrices that produce no matrix cations in MELDI and are suitable for small cationic salts. The actual value of this effective temperature significantly depends on an accurate determination of the threshold dissociation energies and on the time spent in the source, in addition to the statistical hypothesis itself. The method could be applied to normalize spectra in order to compare results issued from different instruments. [less ▲]

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See detailTelomestatin-induced stabilization of the human telomeric DNA quadruplex monitored by electrospray mass spectrometry
Rosu, Frédéric ULg; Gabelica, Valérie ULg; Shin-ya, Kazuo et al

in Chemical Communications (2003), (21), 2702-2703

Electrospray mass spectrometry (ESI-MS) was used to monitor the kinetics of duplex formation between the human telomeric DNA quadruplex and its complementary strand; the complexation of telomestatin to ... [more ▼]

Electrospray mass spectrometry (ESI-MS) was used to monitor the kinetics of duplex formation between the human telomeric DNA quadruplex and its complementary strand; the complexation of telomestatin to the G-quadruplex delays the unwinding of the quadruplex structure and formation of the duplex. [less ▲]

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See detailDioxins, furans and co-planar PCBs in juvenile harbour porpoises (Phocoena phocoena) from the Belgian coasts
Beans, Cristina ULg; Das, Krishna ULg; Jauniaux, Thierry ULg et al

Poster (2003)

Dioxins, furans and PCBs are lipophilic anthropogenic contaminants that have found their way into marine food webs and accumulate in top predators such as marine mammals, adding a stress factor to an ... [more ▼]

Dioxins, furans and PCBs are lipophilic anthropogenic contaminants that have found their way into marine food webs and accumulate in top predators such as marine mammals, adding a stress factor to an already vulnerable population. In this study 7 congeners of dioxins (PCDDs), 10 congeners of furans (PCDFs) and 4 congeners of coplanar PCBs (cPCBs) were determined using high resolution gas chromatography and mass spectrometry in the blubber of 19 juvenile harbour porpoises (Phocoena phocoena) stranded along the Belgian North Sea coastline between 1995 and 2001. These results were contrasted with nutritional status (emaciated or not), sex and trophic level (through stable carbon and nitrogen isotope analysis). Mean blubber concentrations of SPCDD/Fs were 12.8 pg/g lw (lipid weight) and mean related toxicity 1.84 pg TEQs/g lw (TEQs = TCDD toxic equivalents). Mean cPCB concentrations were 223,5 pg/g lw and mean related toxicity 4,47 pg TEQs/g lw. The levels detected in these individuals were of the same order as those found in a previous study in the Wadden Sea (Bruhn, 1999). Both sexes show rather similar levels. No significant relationship was observed between stable carbon or nitrogen isotope values and pollutant levels. Concentrations and toxicity show a tendency to be higher in emaciated ndividuals than in nonemaciated ones. This could indicate a possible relationship between the nutritional status of the animals and dioxinlike pollutants (which could participate in weakening the animal). This situation should be further studied on adult individuals in order to obtain a more global view of the possible effects on the population. [less ▲]

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See detailCalibration of ion effective temperatures achieved by resonant activation in a quadrupole ion trap
Gabelica, Valérie ULg; Karas, Michael; De Pauw, Edwin ULg

in Analytical Chemistry (2003), 75(19), 5152-5159

The present paper describes a calibration of the ion effective temperatures as a function of the resonant activation amplitude in a quadrupole ion trap mass spectrometer. MS/MS experiments are performed ... [more ▼]

The present paper describes a calibration of the ion effective temperatures as a function of the resonant activation amplitude in a quadrupole ion trap mass spectrometer. MS/MS experiments are performed on leucine enkephalin (M + H)(+), bradykinin (M + H)(+), (M + 2H)(2+), and (M + 3H)(3+), and ubiquitin (M + 11H)(11+). For each amplitude, the effective temperature is calculated as the temperature that would give the same dissociation rate constant as the one observed and is calculated using published Arrhenius parameters. The effective temperature is found to be linearly dependent on the activation amplitude on the range investigated. The dependence of the slope and of the intercept of the T-eff = f (amplitude) functions on the parent ion m/z is examined and an equation is derived to calibrate the ion effective temperature between 365 and 600 K Below 365 K, a deviation from linearity is expected. Above 600 1 the validity of the equation will depend on whether the rapid energy exchange limit is still reached. Calculating backward, the Arrhenius parameters from the measured dissociation rates using this calibration show excellent agreement with the published values. The calibration can therefore be used to determine Arrhenius activation parameters from dissociation kinetics under resonant activation in quadrupole ion trap mass spectrometers. [less ▲]

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See detailFast automated extraction and clean-up of biological fluids for polychlorinated dibenzo-p-dioxins, dibenzofurans and coplanar polychlorinated biphenyls analysis
Focant, Jean-François ULg; De Pauw, Edwin ULg

in Journal of Chromatography. B : Analytical Technologies in the Biomedical & Life Sciences (2002), 776(2), 199-212

A fast automated extraction and clean-up procedure for low-level analysis of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and coplanar polychlorinated biphenyls (cPCBs ... [more ▼]

A fast automated extraction and clean-up procedure for low-level analysis of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and coplanar polychlorinated biphenyls (cPCBs) in biological fluids is presented. Online extraction of prepared fluids is carried out using disposable octadecyl bonded (C-18) solid-phase extraction columns. Extracts are then cleaned up through disposable multi-layer silica (acidic, basic and neutral) and dispersed PX-21 carbon columns. This new methodology is compared with classical Soxhlet extraction and manual solid-phase extraction in terms of repeatability, reproducibility, accuracy and recovery rates for reference and certified materials. Robustness is evaluated on different matrices, such as cow's milk, breast milk and human serum. As a consequence of the reduced number of reusable glassware used, as well as lowering of solvent consumption, recorded blank levels are decreased in favor of limits of detection (LODs). Total analysis time and cost are further reduced using simultaneous sample preparation units and the sample throughput is increased compared to classical methods. As a result, this new approach appears to be suitable for the fast sample preparation often required for such fluids in case of emergency foodstuffs analysis or during large epidemiological studies. (C) 2002 Elsevier Science B.V. All rights reserved. [less ▲]

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