oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2020 ( 2 )

2019 ( 206 )

2018 ( 320 )

2017 ( 296 )

Custom range...

Search Results: 1 - 10 of 297486 matches for " J. Dhooghe "
All listed articles are free for downloading (OA Articles)
Page 1 /297486
Display every page Item
MS/MS studies on the selective on-line detection of sesquiterpenes using a flowing afterglow-tandem mass spectrometer
J. Rimetz-Planchon,F. Dhooghe,N. Schoon,F. Vanhaecke
Atmospheric Measurement Techniques Discussions , 2010, DOI: 10.5194/amtd-3-4285-2010
Abstract: A Flowing Afterglow-Tandem Mass Spectrometer (FA-TMS) was used to investigate the feasibility of selective on-line detection of a series of seven sesquiterpenes (SQTs). These SQTs were chemically ionized by either H3O+ or NO+ reagent ions in the FA, resulting among others in protonated SQT and SQT molecular ions, respectively. These and other Chemical Ionization (CI) product ions were subsequently subjected to dissociation by collisions with Ar atoms in the collision cell of the tandem mass spectrometer. The fragmentation spectra show similarities with mass spectra obtained for these compounds with other instruments such as a Proton Transfer Reaction-Linear Ion Trap (PTR-LIT), a Proton Transfer Reaction-Mass Spectrometer (PTR-MS), a Triple Quadrupole-Mass Spectrometer (QqQ-MS) and a Selected Ion Flow Tube-Mass Spectrometer (SIFT-MS). Fragmentation of protonated SQT is characterized by fragment ions at the same masses but with different intensities for the individual SQT. Distinction of SQTs is based on well-chosen intensity ratios and collision energies. The fragmentation patterns of SQT molecular ions show specific fragment ion tracers at m/z 119, m/z 162, m/z 137 and m/z 131 for α-cedrene, δ-neoclovene, isolongifolene and α-humulene, respectively. Consequently, chemical ionization of SQT by NO+, followed by MS/MS of SQT+ seems to open a way for selective quantification of SQTs in mixtures.
MS/MS studies on the selective on-line detection of sesquiterpenes using a Flowing Afterglow–Tandem Mass Spectrometer (FA-TMS)
J. Rimetz-Planchon, F. Dhooghe, N. Schoon, F. Vanhaecke,C. Amelynck
Atmospheric Measurement Techniques (AMT) & Discussions (AMTD) , 2011,
Abstract: A Flowing Afterglow-Tandem Mass Spectrometer (FA-TMS) was used to investigate the feasibility of selective on-line detection of a series of seven sesquiterpenes (SQTs). These SQTs were chemically ionized by either H3O+ or NO+ reagent ions in the FA, resulting among others in protonated SQT and SQT molecular ions, respectively. These and other Chemical Ionization (CI) product ions were subsequently subjected to dissociation by collisions with Ar atoms in the collision cell of the tandem mass spectrometer. The fragmentation spectra show similarities with mass spectra obtained for these compounds with other instruments such as a Proton Transfer Reaction-Linear Ion Trap (PTR-LIT), a Proton Transfer Reaction-Mass Spectrometer (PTR-MS), a Triple Quadrupole-Mass Spectrometer (QqQ-MS) and a Selected Ion Flow Tube-Mass Spectrometer (SIFT-MS). Fragmentation of protonated SQT is characterized by fragment ions at the same masses but with different intensities for the individual SQT. Distinction of SQTs is based on well-chosen intensity ratios and collision energies. The fragmentation patterns of SQT molecular ions show specific fragment ion tracers at m/z 119, m/z162, m/z 137 and m/z 131 for α-cedrene, δ-neoclovene, isolongifolene and α-humulene, respectively. Consequently, chemical ionization of SQT by NO+, followed by MS/MS of SQT+ seems to open a way for selective quantification of SQTs in mixtures.
Multilocal invariants for the classical groups
Paul F. Dhooghe
International Journal of Mathematics and Mathematical Sciences , 2003, DOI: 10.1155/s016117120301233x
Abstract: Multilocal higher-order invariants, which are higher-order invariants defined at distinct points of representation space, for the classical groups are derived in a systematic way. The basic invariants for the classical groups are the well-known polynomial or rational invariants as derived from the Capelli identities. Higher-order invariants are then constructed from the former ones by means of total derivatives. At each order, it appears that the invariants obtained in this way do not generate all invariants. The necessary additional invariants are constructed from the invariant polynomials on the Lie algebra of the Lie transformation groups.
Dysregulated Proinflammatory and Fibrogenic Phenotype of Fibroblasts in Cystic Fibrosis
Fran?ois Huaux, Sabrina Noel, Barbara Dhooghe, Nadtha Panin, Sandra Lo Re, Dominique Lison, Pierre Wallemacq, Etienne Marbaix, Bob J. Scholte, Patrick Lebecque, Teresinha Leal
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0064341
Abstract: Morbi-mortality in cystic fibrosis (CF) is mainly related to chronic lung infection and inflammation, uncontrolled tissue rearrangements and fibrosis, and yet the underlying mechanisms remain largely unknown. We evaluated inflammatory and fibrosis responses to bleomycin in F508del homozygous and wild-type mice, and phenotype of fibroblasts explanted from mouse lungs and skin. The effect of vardenafil, a cGMP-specific phosphodiesterase type 5 inhibitor, was tested in vivo and in culture. Responses of proinflammatory and fibrotic markers to bleomycin were enhanced in lungs and skin of CF mice and were prevented by treatment with vardenafil. Purified lung and skin fibroblasts from CF mice proliferated and differentiated into myofibroblasts more prominently and displayed higher sensitivity to growth factors than those recovered from wild-type littermates. Under inflammatory stimulation, mRNA and protein expression of proinflammatory mediators were higher in CF than in wild-type fibroblasts, in which CFTR expression reached similar levels to those observed in other non-epithelial cells, such as macrophages. Increased proinflammatory responses in CF fibroblasts were reduced by half with submicromolar concentrations of vardenafil. Proinflammatory and fibrogenic functions of fibroblasts are upregulated in CF and are reduced by vardenafil. This study provides compelling new support for targeting cGMP signaling pathway in CF pharmacotherapy.
Comparative Variability of Nasal Potential Difference Measurements in Human and Mice  [PDF]
Anissa Leonard, Bob Lubamba, Barbara Dhooghe, Sabrina Noel, Pierre Wallemacq, Patrick Lebecque, Teresinha Leal
Open Journal of Respiratory Diseases (OJRD) , 2012, DOI: 10.4236/ojrd.2012.22007
Abstract: Background: Nasal potential difference (NPD) test has long been used to assist in the diagnosis of Cystic Fibrosis (CF) and more recently as an outcome measure in clinical trials of new CF therapies. This test has also been adapted to the mouse nose. Objectives: We aimed at evaluating variability of the NPD measurements in CF patients displaying two severe CFTR mutations and in sex-matched healthy controls. NPD recorded from F508del-CF and normal wild-type mice were also compared. Methods and results: In each setting, tests were performed by a single qualified operator. In the clinical setting, the latest standardized operation protocol of the CF foundation was followed. A total of 80 tracings were obtained from 10 patients (23.2 y; range 14 to 32) and 10 healthy subjects (34 y; range 24 to 53), each tested twice, in both nostrils. Two CF and two controls were excluded from the statistical data analysis due to the presence of a single non interpretable NPD tracing (4/80, 5%). To achieve equal sample size, tests were obtained from 8 CF mice and normal wild-type. Comprehensive multivariate analysis of paired data showed a good reproducibility of NPD parameters in the clinical and the preclinical setting; lower variability was observed in mice. However, 95% repeatability limits of NPD parameters were large indicating a large measurement error, poor precision and low within-subject repeatability. In both settings, chloride secretion was shown to be the most reproducible and repeatable parameter. Conclusion: In human as in mice, NPD showed good reproducibility but limited within-subject repeatability.
PDE5 Inhibitors as Potential Tools in the Treatment of Cystic Fibrosis
Sabrina Noel,Barbara Dhooghe,Teresinha Leal
Frontiers in Pharmacology , 2012, DOI: 10.3389/fphar.2012.00167
Abstract: Despite great advances in the understanding of the genetics and pathophysiology of cystic fibrosis (CF), there is still no cure for the disease. Using phosphodiesterase type 5 (PDE5) inhibitors, we and others have provided evidence of rescued F508del-CFTR trafficking and corrected deficient chloride transport activity. Studies using PDE5 inhibitors in mice homozygous for the clinically relevant F508del mutation have been conducted with the aim of restoring F508del-CFTR protein function. We demonstrated, by measuring transepithelial nasal potential difference in F508del mice following intraperitoneal injection of sildenafil, vardenafil, or taladafil at clinical doses are able to restore the decreased CFTR-dependent chloride transport across the nasal mucosa. Moreover, vardenafil, but not sildenafil, stimulates chloride transport through the normal CFTR protein. We developed a specific nebulizer setup for mice, with which we demonstrated, through a single inhalation of PDE5 inhibitors, local activation of CFTR protein in CF. Significant potential advantages of inhalation drug therapy over oral or intravenous routes include rapid onset of pharmacological action, reduced systemic secondary effects, and reduced effective drug doses compared to the drug delivered orally; this underlines the relevance and impact of our work for translational science. More recently, we analyzed the bronchoalveolar lavage of CF and wild-type mice for cell infiltrates and expression of pro-inflammatory cytokines and chemokines; we found that the CFTR activating effect of vardenafil, selected as a representative long-lasting PDE5 inhibitor, breaks the vicious circle of lung inflammation which plays a major role in morbi-mortality in CF. Our data highlight the potential use of PDE5 inhibitors in CF. Therapeutic approaches using clinically approved PDE5 inhibitors to address F508del-CFTR defects could speed up the development of new therapies for CF.
Characterization of the Hamamatsu R11780 12 inch Photomultiplier Tube
J. Brack,B. Delgado,J. Dhooghe,J. Felde,B. Gookin,S. Grullon,J. R. Klein,R. Knapik,A. LaTorre,S. Seibert,K. Shapiro,R. Svoboda,L. Ware,R. Van Berg
Physics , 2012, DOI: 10.1016/j.nima.2013.02.022
Abstract: Future large water Cherenkov and scintillator detectors have been proposed for measurements of long baseline neutrino oscillations, proton decay, supernova and solar neutrinos. To ensure cost-effectiveness and optimize scientific reach, one of the critical requirements for such detectors are large-area, high performance photomultiplier tubes (PMTs). One candidate for such a device is the Hamamatsu R11780, a 12" PMT that is available in both standard and high quantum efficiency versions. Measurements of the single photoelectron response characteristics, relative efficiencies of the standard and high quantum efficiency versions, a preliminary measurement of the absolute quantum efficiency of the standard quantum efficiency version, and a two-dimensional scan of the relative efficiency across the photocathode surface are presented in this paper. All single photoelectron investigations were made using a Cherenkov light source at room temperature at a gain of 1*10^7. These results show that the R11780 PMT is a excellent candidate for such large optical detectors, including the peak-to-valley ratios greater than 2, transit time spreads around 1.3 ns, and late-pulsing probabilities less than 5%.
Correction of Chloride Transport and Mislocalization of CFTR Protein by Vardenafil in the Gastrointestinal Tract of Cystic Fibrosis Mice
Barbara Dhooghe, Sabrina No?l, Caroline Bouzin, Ga?tane Behets-Wydemans, Teresinha Leal
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0077314
Abstract: Although lung disease is the major cause of mortality in cystic fibrosis (CF), gastrointestinal (GI) manifestations are the first hallmarks in 15–20% of affected newborns presenting with meconium ileus, and remain major causes of morbidity throughout life. We have previously shown that cGMP-dependent phosphodiesterase type 5 (PDE5) inhibitors rescue defective CF Transmembrane conductance Regulator (CFTR)-dependent chloride transport across the mouse CF nasal mucosa. Using F508del-CF mice, we examined the transrectal potential difference 1 hour after intraperitoneal injection of the PDE5 inhibitor vardenafil or saline to assess the amiloride-sensitive sodium transport and the chloride gradient and forskolin-dependent chloride transport across the GI tract. In the same conditions, we performed immunohistostaining studies in distal colon to investigate CFTR expression and localization. F508del-CF mice displayed increased sodium transport and reduced chloride transport compared to their wild-type littermates. Vardenafil, applied at a human therapeutic dose (0.14 mg/kg) used to treat erectile dysfunction, increased chloride transport in F508del-CF mice. No effect on sodium transport was detected. In crypt colonocytes of wild-type mice, the immunofluorescence CFTR signal was mostly detected in the apical cell compartment. In F508del-CF mice, a 25% reduced signal was observed, located mostly in the subapical region. Vardenafil increased the peak of intensity of the fluorescence CFTR signal in F508del-CF mice and displaced it towards the apical cell compartment. Our findings point out the intestinal mucosa as a valuable tissue to study CFTR transport function and localization and to evaluate efficacy of therapeutic strategies in CF. From our data we conclude that vardenafil mediates potentiation of the CFTR chloride channel and corrects mislocalization of the mutant protein. The study provides compelling support for targeting the cGMP signaling pathway in CF pharmacotherapy.
Improved measurements of the neutrino mixing angle $θ_{13}$ with the Double Chooz detector
Y. Abe,J. C. dos Anjos,J. C. Barriere,E. Baussan,I. Bekman,M. Bergevin,T. J. C. Bezerra,L. Bezrukov,E. Blucher,C. Buck,J. Busenitz,A. Cabrera,E. Caden,L. Camilleri,R. Carr,M. Cerrada,P. -J. Chang,E. Chauveau,P. Chimenti,A. P. Collin,E. Conover,J. M. Conrad,J. I. Crespo-Anadón,K. Crum,A. S. Cucoanes,E. Damon,J. V. Dawson,J. Dhooghe,D. Dietrich,Z. Djurcic,M. Dracos,M. Elnimr,A. Etenko,M. Fallot,F. von Feilitzsch,J. Felde,S. M. Fernandes,V. Fischer,D. Franco,M. Franke,H. Furuta,I. Gil-Botella,L. Giot,M. G?ger-Neff,L. F. G. Gonzalez,L. Goodenough,M. C. Goodman,C. Grant,N. Haag,T. Hara,J. Haser,M. Hofmann,G. A. Horton-Smith,A. Hourlier,M. Ishitsuka,J. Jochum,C. Jollet,F. Kaether,L. N. Kalousis,Y. Kamyshkov,D. M. Kaplan,T. Kawasaki,E. Kemp,H. de Kerret,D. Kryn,M. Kuze,T. Lachenmaier,C. E. Lane,T. Lasserre,A. Letourneau,D. Lhuillier,H. P. Lima Jr,M. Lindner,J. M. López-Casta?o,J. M. LoSecco,B. Lubsandorzhiev,S. Lucht,J. Maeda,C. Mariani,J. Maricic,J. Martino,T. Matsubara,G. Mention,A. Meregaglia,T. Miletic,R. Milincic,A. Minotti,Y. Nagasaka,Y. Nikitenko,P. Novella,L. Oberauer,M. Obolensky,A. Onillon,A. Osborn,C. Palomares,I. M. Pepe,S. Perasso,P. Pfahler,A. Porta,G. Pronost,J. Reichenbacher,B. Reinhold,M. R?hling,R. Roncin,S. Roth,B. Rybolt,Y. Sakamoto,R. Santorelli,A. C. Schilithz,S. Sch?nert,S. Schoppmann,M. H. Shaevitz,R. Sharankova,S. Shimojima,D. Shrestha,V. Sibille,V. Sinev,M. Skorokhvatov,E. Smith,J. Spitz,A. Stahl,I. Stancu,L. F. F. Stokes,M. Strait,A. Stüken,F. Suekane
Physics , 2014, DOI: 10.1007/JHEP10(2014)086
Abstract: The Double Chooz experiment presents improved measurements of the neutrino mixing angle $\theta_{13}$ using the data collected in 467.90 live days from a detector positioned at an average distance of 1050 m from two reactor cores at the Chooz nuclear power plant. Several novel techniques have been developed to achieve significant reductions of the backgrounds and systematic uncertainties with respect to previous publications, whereas the efficiency of the $\bar\nu_{e}$ signal has increased. The value of $\theta_{13}$ is measured to be $\sin^{2}2\theta_{13} = 0.090 ^{+0.032}_{-0.029}$ from a fit to the observed energy spectrum. Deviations from the reactor $\bar\nu_{e}$ prediction observed above a prompt signal energy of 4 MeV and possible explanations are also reported. A consistent value of $\theta_{13}$ is obtained from a fit to the observed rate as a function of the reactor power independently of the spectrum shape and background estimation, demonstrating the robustness of the $\theta_{13}$ measurement despite the observed distortion.
Ortho-positronium observation in the Double Chooz Experiment
Y. Abe,J. C. dos Anjos,J. C. Barriere,E. Baussan,I. Bekman,M. Bergevin,T. J. C. Bezerra,L. Bezrukov,E. Blucher,C. Buck,J. Busenitz,A. Cabrera,E. Caden,L. Camilleri,R. Carr,M. Cerrada,P. -J. Chang,E. Chauveau,P. Chimenti,A. P. Collin,E. Conover,J. M. Conrad,J. I. Crespo-Anadon,K. Crum,A. S. Cucoanes,E. Damon,J. V. Dawson,J. Dhooghe,D. Dietrich,Z. Djurcic,M. Dracos,M. Elnimr,A. Etenko,M. Fallot,F. von Feilitzsch,J. Felde,S. M. Fernandes,V. Fischer,D. Franco,M. Franke,H. Furuta,I. Gil-Botella,L. Giot,M. Goger-Neff,L. F. G. Gonzalez,L. Goodenough,M. C. Goodman,C. Grant,N. Haag,T. Hara,J. Haser,M. Hofmann,G. A. Horton-Smith,A. Hourlier,M. Ishitsuka,J. Jochum,C. Jollet,F. Kaether,L. N. Kalousis,Y. Kamyshkov,D. M. Kaplan,T. Kawasaki,E. Kemp,H. de Kerret,D. Kryn,M. Kuze,T. Lachenmaier,C. E. Lane,T. Lasserre,A. Letourneau,D. Lhuillier,H. P. Lima Jr,M. Lindner,J. M. Lopez-Castano,J. M. LoSecco,B. Lubsandorzhiev,S. Lucht,J. Maeda,C. Mariani,J. Maricic,J. Martino,T. Matsubara,G. Mention,A. Meregaglia,T. Miletic,R. Milincic,A. Minotti,Y. Nagasaka,Y. Nikitenko,P. Novella,L. Oberauer,M. Obolensky,A. Onillon,A. Osborn,C. Palomares,I. M. Pepe,S. Perasso,P. Pfahler,A. Porta,G. Pronost,J. Reichenbacher,B. Reinhold,M. Rohling,R. Roncin,S. Roth,B. Rybolt,Y. Sakamoto,R. Santorelli,A. C. Schilithz,S. Schonert,S. Schoppmann,M. H. Shaevitz,R. Sharankova,S. Shimojima,D. Shrestha,V. Sibille,V. Sinev,M. Skorokhvatov,E. Smith,J. Spitz,A. Stahl,I. Stancu,L. F. F. Stokes,M. Strait,A. Stuken,F. Suekane
Statistics , 2014, DOI: 10.1007/JHEP10(2014)032
Abstract: The Double Chooz experiment measures the neutrino mixing angle $\theta_{13}$ by detecting reactor $\bar{\nu}_e$ via inverse beta decay. The positron-neutron space and time coincidence allows for a sizable background rejection, nonetheless liquid scintillator detectors would profit from a positron/electron discrimination, if feasible in large detector, to suppress the remaining background. Standard particle identification, based on particle dependent time profile of photon emission in liquid scintillator, can not be used given the identical mass of the two particles. However, the positron annihilation is sometimes delayed by the ortho-positronium (o-Ps) metastable state formation, which induces a pulse shape distortion that could be used for positron identification. In this paper we report on the first observation of positronium formation in a large liquid scintillator detector based on pulse shape analysis of single events. The o-Ps formation fraction and its lifetime were measured, finding the values of 44$\%$ $\pm$ 12$\%$ (sys.) $\pm$ 5$\%$ (stat.) and $3.68$ns $\pm$ 0.17ns (sys.) $\pm$ 0.15ns (stat.) respectively, in agreement with the results obtained with a dedicated positron annihilation lifetime spectroscopy setup.
Page 1 /297486
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.