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See detailOrigin of the counterintuitive dynamic charge in the transition metal dichalcogenides
Pike, Nicholas ULg; Van Troeye, Benoit; Dewandre, Antoine ULg et al

in Physical Review B (2017), 95

Despite numerous studies of transition metal dichalcogenides, the diversity of their chemical bonding characteristics and charge transfer is not well understood. Based on density functional theory we ... [more ▼]

Despite numerous studies of transition metal dichalcogenides, the diversity of their chemical bonding characteristics and charge transfer is not well understood. Based on density functional theory we investigate their static and dynamic charges. The dynamic charge of the transition metal dichalcogenides with trigonal symmetry are anomalously large, while in their hexagonally symmetric counterparts, we even observe a counterintuitive sign, i.e., the transition metal takes a negative charge, opposite to its static charge. This phenomenon, so far never remarked on or analyzed, is understood by investigating the perturbative response of the system and by investigating the hybridization of the molecular orbitals near the Fermi level. Furthermore, a link is established between the sign of the Born effective charge and the process of π backbonding from organic chemistry. Experiments are proposed to verify the calculated sign of the dynamical charge in these materials. Employing a high-throughput search we also identify other materials that present counterintuitive dynamic charges. [less ▲]

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See detailLes épreuves multiples chez les jeunes. Réflexion sur un programme développemental à long terme.
Jidovtseff, Boris ULg

Learning material (2017)

Réflexion personnelle sur une proposition de modèle développemental à long terme spécifique aux épreuves multiples en athlétisme.

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See detailRégimes matrimoniaux et effets patrimoniaux des partenariats enregistrés en Europe. Propos introductifs
Wautelet, Patrick ULg

in Droit de la famille (2017), 22(5), 10-13

Ce bref texte présente quelques propos introductifs destinés à situer les règlements 2016/1103 et 2016/1104. Le texte s'attarde sur l'histoire de ces règlements, leur plus-value et esquisse certaines des ... [more ▼]

Ce bref texte présente quelques propos introductifs destinés à situer les règlements 2016/1103 et 2016/1104. Le texte s'attarde sur l'histoire de ces règlements, leur plus-value et esquisse certaines des questions ouvertes qu'ils posent [less ▲]

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See detailTranscriptome wide analysis of natural antisense transcripts shows potential role in breast cancer
Wenric, Stéphane ULg; El Guendi, Sonia; CABERG, Jean-Hubert ULg et al

Poster (2017, May)

Non-coding RNAs (ncRNA) represent at least 1/5 of the mammalian transcript amount, and about 90% of the genome length is actively transcribed. Many ncRNAs have been demonstrated to play a role in cancer ... [more ▼]

Non-coding RNAs (ncRNA) represent at least 1/5 of the mammalian transcript amount, and about 90% of the genome length is actively transcribed. Many ncRNAs have been demonstrated to play a role in cancer. Among them, natural antisense transcripts (NAT) are RNA sequences which are complementary and overlapping to those of protein-coding transcripts (PCT). NATs were punctually described as regulating gene expression, and are expected to act more frequently in cis than other ncRNAs that commonly function in trans. In this work, 22 breast cancers expressing estrogen receptors and their paired healthy tissues were analyzed by strand-specific RNA sequencing. To highlight the potential role of NATs in gene regulations occurring in breast cancer, three different gene extraction methods were used: differential expression analysis of NATs between tumor and healthy tissues, differential correlation analysis of paired NAT/PCT between tumor and healthy tissues, and NAT/PCT read count ratio variation between tumor and healthy tissues. Each of these methods yielded lists of NAT/PCT pairs that were demonstrated to be enriched in survival-associated genes on an independent cohort (TCGA). This work allows to highlight NAT lists that display a strong potential to affect the expression of genes involved in the breast cancer pathology. [less ▲]

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See detailDeciphering the role of dendritic sodium channels on action potential dynamics in substantia nigra dopaminergic neurons
Moubarak, Estelle; Engel, Dominique ULg; Dufour, Martial et al

Poster (2017, May)

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See detailAdvanced method optimization for volatile aroma profiling of beer using two-dimensional gas chromatography time-of-flight mass spectrometry
Stefanuto, Pierre-Hugues ULg; Perrault, Katelynn ULg; Dubois, Lena ULg et al

in Journal of Chromatography. A (2017)

The complex mixture of volatile organic compounds (VOCs) present in the headspace of Trappist and craft beers was studied to illustrate the efficiency of thermal desorption (TD) comprehensive two ... [more ▼]

The complex mixture of volatile organic compounds (VOCs) present in the headspace of Trappist and craft beers was studied to illustrate the efficiency of thermal desorption (TD) comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-TOFMS) for highlighting subtle differences between highly complex mixtures of VOCs. Headspace solid-phase microextraction (HS-SPME), multiple (and classical) stir bar sorptive extraction (mSBSE), static headspace (SHS), and dynamic headspace (DHS) were compared for the extraction of a set of 21 representative flavor compounds of beer aroma. A Box-Behnken surface response methodology experimental design optimization (DOE) was used for convex hull calculation (Delaunay’s triangulation algorithms) of peak dispersion in the chromatographic space. The predicted value of 0.5 for the ratio between the convex hull and the available space was 10% higher than the experimental value, demonstrating the usefulness of the approach to improve optimization of the GC × GC separation. Chemical variations amongst aligned chromatograms were studied by means of Fisher Ratio (FR) determination and F‐distribution threshold filtration at different significance levels (α = 0.05 and 0.01) and based on z‐score normalized area for data reduction. Statistically significant compounds were highlighted following principal component analysis (PCA) and hierarchical cluster analysis (HCA). The dendrogram structure not only provided clear visual information about similarities between products but also permitted direct identification of the chemicals and their relative weight in clustering. The effective coupling of DHS-TD-GC × GC-TOFMS with PCA and HCA was able to highlight the differences and common typical VOC patterns among 24 samples of different Trappist and selected Canadian craft beers. [less ▲]

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See detailDiscovery and pharmacological characterization of succinate receptor (SUCNR1/GPR91) agonists
Geubelle, Pierre ULg; Gilissen, Julie; Dilly, Sebastien et al

in British Journal of Pharmacology (2017), 174(9), 796-808

Background and Purpose The succinate receptor (SUCNR1 or GPR91) has been described as a metabolic sensor that may be involved in homeostasis. Notwithstanding its implication in important (patho ... [more ▼]

Background and Purpose The succinate receptor (SUCNR1 or GPR91) has been described as a metabolic sensor that may be involved in homeostasis. Notwithstanding its implication in important (patho)physiological processes, the function of SUCNR1 has remained elusive because no pharmacological tools were available. We report on the discovery of the first family of synthetic potent agonists. Experimental Approach We screened a library of succinate analogues and analysed their activity on SUCNR1. In addition, we modelled a pharmacophore and a binding site for the receptor. New agonists were identified based on the information provided by these two approaches. Their activity was studied in various bioassays, including measurement of cAMP levels, [Ca2+]i mobilisation, TGF-α shedding and recruitment of arrestin 3. The in vivo impact of SUCNR1 activation by these new agonists was evaluated on rat blood pressure. Key Results We identified cis-epoxysuccinic acid and cis-1,2-cyclopropanedicarboxylic acid as agonists with an efficacy similar to the one of succinic acid. Interestingly, cis-epoxysuccinic acid was characterized by a 10 to 20 fold higher potency than succinate on the receptor. For example, cis-epoxysuccinic acid reduced cAMP levels with a pEC50 = 5.57 ± 0.02 (EC50 = 2.7 μM) as compared to succinate pEC50 = 4.54 ± 0.08 (EC50 = 29 μM). The rank order of potency of the three agonists was the same in all bioassays tested. In vivo, cis-epoxysuccinic and cis-1,2-cyclopropanedicarboxylic acid increased rat blood pressure to the same extent as succinate did. Conclusions and Implications We provide new agonist tools for SUCNR1 that should facilitate further research on this understudied receptor. [less ▲]

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See detailInfluence qualitative et quantitative du mode de séchage sur l'huile essentielle de Thymus fontanesii de l'Algérie
Sidali, Lamia; Brada, Moussa; Fauconnier, Marie-Laure ULg et al

Poster (2017, May)

Cette étude a pour but d`étudier l`influence du mode de séchage (à l’ombre et au soleil) sur le rendement et la composition chimique de l`huile essentielle de Thymus fontanesii de l`Algérie obtenue par ... [more ▼]

Cette étude a pour but d`étudier l`influence du mode de séchage (à l’ombre et au soleil) sur le rendement et la composition chimique de l`huile essentielle de Thymus fontanesii de l`Algérie obtenue par extraction assistée par induction électromagnétique. Les résultats ont montré que le séchage à l`ombre a donné un meilleur rendement de (1.12%) après une période de séchage de 10 jours jusqu`à la stabilisation de teneur en eau, alors que le séchage au soleil pendant 8 jours donne un rendement de (0.89%). La composition chimique de l`huile essentielle de Thymus fontanesii (TF) a été analysé par la chromatographie en phase gazeuse couplée à la spectrométrie de masse (GC/MS) et la chromatographie en phase gazeuse a ionisation de flamme (GC/FID). [less ▲]

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See detailIntroduction aux doctrines et aux idées politiques: une approche structurale
Claisse, Frédéric ULg; Counet, Maxime ULg; Verjans, Pierre ULg

Book published by De Boeck Supérieur (2017)

Comment s’articulent les grandes doctrines et idées politiques ? En quoi des auteurs comme Machiavel ou La Boétie peuvent-ils nous aider à comprendre l’exercice du pouvoir et la résistance à la domination ... [more ▼]

Comment s’articulent les grandes doctrines et idées politiques ? En quoi des auteurs comme Machiavel ou La Boétie peuvent-ils nous aider à comprendre l’exercice du pouvoir et la résistance à la domination ? Quels sont les clivages qui constituent la toile de fond de la vie politique ? De Bodin à Maurras et Renan, de Condorcet à Sen, de Montesquieu à Hayek et de Marx à Rawls et Piketty, en passant par Hobbes, Locke et Bossuet, les grands auteurs ont apporté des réponses à quatre questions fondamentales auxquelles toute société se trouve confrontée : Qui sommes-nous ? Pourquoi vivons-nous ensemble ? Comment produisons-nous ? Comment distribuons-nous nos richesses ? Ces réponses continuent d’influencer en profondeur les débats politiques. Plutôt que de présenter les doctrines politiques en familles idéologiques homogènes (libéralisme, socialisme, conservatisme), cet ouvrage met en évidence les unités de base qui sous-tendent les principaux énoncés politiques, quelle que soit l’étiquette sous laquelle ils circulent. Fruit de nombreuses années d’analyse et d’enseignement, ce manuel offre un point de vue original sur les doctrines et idées politiques, à travers une approche structurale qui insiste sur les jeux d’oppositions et de priorités, tout en passant en revue des œuvres fondatrices de notre imaginaire politique. Pour les étudiants, qui trouveront dans cet ouvrage une introduction aux doctrines et idées politiques, ainsi qu’une approche analytique des grands auteurs. Pour les citoyens, à qui il fournira des ressources pour mieux s’orienter parmi les positionnements politiques et en comprendre la logique. [less ▲]

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See detailExperimental and Numerical Study of Mini-UAV Propeller Performance in Oblique Flow
Theys, Bart; Dimitriadis, Grigorios ULg; Hendrick, Patrick et al

in Journal of Aircraft (2017), 54(3), 1076-1084

This paper presents the modelling of the performance of small propellers used for Vertical Take Off and Landing Micro Aerial Vehicles (VTOL MAVs) operating at low Reynolds numbers and in oblique flow ... [more ▼]

This paper presents the modelling of the performance of small propellers used for Vertical Take Off and Landing Micro Aerial Vehicles (VTOL MAVs) operating at low Reynolds numbers and in oblique flow. Blade Element Momentum Theory (BEMT), Vortex Lattice Method (VLM) and momentum theory for oblique flow are used to predict propeller performance. For validation, the predictions for a commonly used propeller for VTOL MAVs are compared to a set of wind tunnel experiments. Both BEMT and VLM succeed in predicting correct trends of the forces and moments acting upon the propeller shaft, although accuracy decreases significantly in oblique flow. For the dataset analysed here, combining the available data of the propeller in purely axial flow with momentum theory for oblique flow and applying a correction factor for the wake skew angle results in more accurate performance estimates at all elevation angles. [less ▲]

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See detailExperimental passive flutter suppression using a linear tuned vibration absorber
Verstraelen, Edouard ULg; Habib, Giuseppe ULg; Kerschen, Gaëtan ULg et al

in AIAA Journal (2017), 55(5), 1707-1722

The current drive for increased efficiency in aeronautic structures such as aircraft, wind turbine blades and helicopter blades often leads to weight reduction. A con- sequence of this tendency can be ... [more ▼]

The current drive for increased efficiency in aeronautic structures such as aircraft, wind turbine blades and helicopter blades often leads to weight reduction. A con- sequence of this tendency can be increased flexibility, which in turn can lead to un- favourable aeroelastic phenomena involving large amplitude oscillations and non- linear effects such as geometric hardening and stall flutter. Vibration mitigation is one of the approaches currently under study for avoiding these phenomena. In the present work, passive vibration mitigation is applied to a nonlinear experimental aeroelastic system by means of a linear tuned vibration absorber. The aeroelastic apparatus is a pitch and flap wing that features a continuously hardening restoring torque in pitch and a linear restoring torque in flap. Extensive analysis of the sys- tem with and without absorber at pre-critical and post-critical airspeeds showed an improvement in flutter speed of around 36%, a suppression of a jump due to stall flutter, and a reduction in LCO amplitude. Mathematical modelling of the exper- imental system is used to demonstrate that optimal flutter delay is achieved when two of the system modes flutter at the same flight condition. Nevertheless, even this optimal absorber quickly loses effectiveness as it is detuned. The wind tunnel mea- surements showed that the tested absorbers were much slower to lose effectiveness than those of the mathematical predictions. [less ▲]

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See detailTransparent Electrodes Based on Silver Nanowire Networks: From Physical Considerations towards Device Integration
Bellet, Daniel; Lagrange, Mélanie; Sannicolo, Thomas et al

in Materials (2017), 10

The past few years have seen a considerable amount of research devoted to nanostructured transparent conducting materials (TCM), which play a pivotal role in many modern devices such as solar cells ... [more ▼]

The past few years have seen a considerable amount of research devoted to nanostructured transparent conducting materials (TCM), which play a pivotal role in many modern devices such as solar cells, flexible light-emitting devices, touch screens, electromagnetic devices, and flexible transparent thin film heaters. Currently, the most commonly used TCM for such applications (ITO: Indium Tin oxide) suffers from two major drawbacks: brittleness and indium scarcity. Among emerging transparent electrodes, silver nanowire (AgNW) networks appear to be a promising substitute to ITO since such electrically percolating networks exhibit excellent properties with sheet resistance lower than 10 Ω/sq and optical transparency of 90%, fulfilling the requirements of most applications. In addition, AgNW networks also exhibit very good mechanical flexibility. The fabrication of these electrodes involves low-temperature processing steps and scalable methods, thus making them appropriate for future use as low-cost transparent electrodes in flexible electronic devices. This contribution aims to briefly present the main properties of AgNW based transparent electrodes as well as some considerations relating to their efficient integration in devices. The influence of network density, nanowire sizes, and post treatments on the properties of AgNW networks will also be evaluated. In addition to a general overview of AgNW networks, we focus on two important aspects: (i) network instabilities as well as an efficient Atomic Layer Deposition (ALD) coating which clearly enhances AgNW network stability and (ii) modelling to better understand the physical properties of these networks. [less ▲]

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See detailThe exclusion of competing one-way essential complements: implications for net neutrality
Broos, Sébastien ULg; Gautier, Axel ULg

in International Journal of Industrial Organization (2017), 52

We analyze the incentives of internet service providers (ISPs) to break net neutrality by excluding competing one-way essential complements, i.e. internet applications competing with their own products. A ... [more ▼]

We analyze the incentives of internet service providers (ISPs) to break net neutrality by excluding competing one-way essential complements, i.e. internet applications competing with their own products. A typical example is the exclusion of VoIP applications by telecom companies offering internet and voice services. A monopoly ISP may want to exclude a competing internet app if it is of inferior quality and the ISP cannot ask for a surcharge for its use. Competition between ISPs never leads to full app exclusion but it may lead to a fragmented internet where only one ISP offers the application. We show that, both in monopoly and duopoly, prohibiting the exclusion of the app and surcharges for its use does not always improve welfare. [less ▲]

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See detailInvestigation of the glycolytic switch induced by saturated fatty acid in human macrophages
Colonval, Megan ULg; Fettweis, Grégory; L'homme, Laurent et al

Poster (2017, May)

Detailed reference viewed: 15 (2 ULg)
See detailIntegrated Geological-Geophysical Models of Unstable Slopes in Seismic Areas
Mreyen, Anne-Sophie ULg; Micu, Mihai; Onaca, Alexandru et al

in Mikos, Matjaz (Ed.) Advancing Culture of Living with Landslides (2017, May)

We will present a series of new integrated 3D models of landslide sites that were investigated in distinctive seismotectonic and climatic contexts: (1) along the Hockai Fault Zone in Belgium and (2) in ... [more ▼]

We will present a series of new integrated 3D models of landslide sites that were investigated in distinctive seismotectonic and climatic contexts: (1) along the Hockai Fault Zone in Belgium and (2) in the seismic region of Vrancea, Romania. Both sites are deep-seated failures located in more or less seismically active areas. In such areas, slope stability analyses have to take into account the possible contributions to ground failure. Our investigation methods had to be adapted to capture the deep structure as well as the physico-mechanical characteristics that influence the dynamic behaviour of the landslide body. Field surveys included electrical resistivity tomography profiles, seismic refraction profiles (analysed in terms of both seismic P-wave tomography and surface waves), ambient noise measurements to determine the soil resonance frequencies through H/V analysis, complemented by geological and geomorphic mapping. The H/V method, in particular, is more and more used for landslide investigations or sites marked by topographic relief (in addition to the more classical applications on flat sites). Results of data interpretation were compiled in 3D geological-geophysical models supported by high resolution remote sensing data of the ground surface. Data and results were not only analysed in parallel or successively; to ensure full integration of all inputs-outputs, some data fusion and geostatistical techniques were applied to establish closer links between them. Inside the 3D models, material boundaries were defined in terms of surfaces and volumes. Those were implemented in 2D and 3D numerical dynamic models (presented in a companion paper). [less ▲]

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See detailPrincipes de contentieux administratif
Pâques, Michel ULg

Book published by Larcier - 1re édition (2017)

L’importance du contentieux administratif n’échappe à personne. La qualité de son traitement donne au droit administratif sa consistance. L’obligation faite à l’administration de s’incliner devant la ... [more ▼]

L’importance du contentieux administratif n’échappe à personne. La qualité de son traitement donne au droit administratif sa consistance. L’obligation faite à l’administration de s’incliner devant la décision du juge permet l’État de droit. Du projet à la pratique, le trajet n’est bien entendu pas toujours rectiligne. La tension entre efficacité, sécurité juridique et légalité est constante, tout comme est ininterrompue la quête d’un meilleur système. En cette matière, les tendances sont longues, mais la réforme est permanente. L’ouvrage a été conçu pour les étudiants de la troisième année du baccalauréat en droit à qui il s’agit de présenter les principes du contentieux, mais aussi les éléments forts du droit positif. Le plan est celui d’un cours, en vue de l’acquisition progressive des connaissances nécessaires à ce qui vient ensuite. La pratique, pour sa part, doit bien entendu tout mettre en œuvre en même temps. L’utilisation de deux types de caractères et de notes permet de viser l’objectif d’une présentation structurante tout en présentant déjà les nuances, les exemples et parfois les conseils immédiatement utiles à la pratique contemporaine. Quelques développements sont consacrés à la manière concrète d’exercer certains recours, comme la formulation d’un moyen dans une requête en annulation. Questions clés : recours administratif, droit au juge et limitations, compétence fédérale, régionale et communautaire en matière de juridiction, droits subjectifs de l’administré, responsabilité de l’administration, faute et illégalité, censure de l’acte illégal, séparation des pouvoirs, pouvoir d’injonction contre l’administration, contentieux objectif et subjectif, Conseil d’État, autorité administrative, recours en annulation, compétence et incompétence du Conseil d’État en raison de l’objet véritable du litige, recevabilité, délais, intérêt au recours et au moyen, référé administratif, annuler ou ne pas annuler l’acte illégal ou limiter les effets de l’annulation, indemnité réparatrice. [less ▲]

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See detailIdentifying novel biomarkers for the rapid diagnosis of invasive aspergillosis using GC×GC-TOFMS
Stefanuto, Pierre-Hugues ULg; Rees, Christiaan A.; Beattie, Sarah R. et al

Conference (2017, May)

Aspergillus fumigatus is a filamentous fungus responsible for the life-threatening infection, invasive aspergillosis (IA), in immunocompromised individuals. Currently, IA diagnostic methods take days to ... [more ▼]

Aspergillus fumigatus is a filamentous fungus responsible for the life-threatening infection, invasive aspergillosis (IA), in immunocompromised individuals. Currently, IA diagnostic methods take days to produce a result and methods to obtain samples are invasive. One approach to improve the time-to-diagnosis is based on utilizing our knowledge of fungal metabolism during pathogenesis. Recent studies have demonstrated the importance of oxygen availability during IA, which presents a potential diagnostic opportunity. In this study, we analyzed the early (1 hr) and late (8 hr) volatile profile of A. fumigatus strain CEA1o under oxygen replete (~20% O2) and deplete (0.2% O2) conditions. In order to comprehensively screen the headspace of these cultures, we applied headspace solid phase microextraction (HS-SPME) associated with comprehensive two-dimensional gas chromatography coupled to time of flight mass spectrometry (GC×GC-TOFMS). Comparing the headspace of the four culture conditions, we were able to identify specific volatile biomarkers of low oxygen fungal growth: ethanol, acetaldehyde, 2-propanol, 2,3-butanedione, and 3-hydroxy-2-butanone. Based on the putative identifications of these compounds, we identified potential metabolic pathways that are responsible for their production. The two first compounds are known to be produced during hypoxia metabolism of glucose, however, the three others suggest that previously uncharacterized metabolic pathways may be utilized by A. fumigatus in low oxygen conditions. Validation of these biomarker identities and translation into patients may generate metabolic insight into these organisms during IA pathogenesis. [less ▲]

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See detailIdentifying infectious agents from lung transplant patients using GC×GC-TOFMS
Stefanuto, Pierre-Hugues ULg; Rees, Christiaan A.; Romamno, Rosalba et al

Poster (2017, May)

During the first year post-surgery, bacterial and fungal infections are the main causes of death in lung transplant recipients. Contributing substantially to the high mortality rate (35%) is the lengthy ... [more ▼]

During the first year post-surgery, bacterial and fungal infections are the main causes of death in lung transplant recipients. Contributing substantially to the high mortality rate (35%) is the lengthy time-to-diagnosis, which includes both pathogen identification and antibiotic resistance profiling. A novel diagnostic strategy based on the detection of volatile compounds in breath seems a promising option to improve these patients’ outcomes. In order to demonstrate the feasibility of this approach, we characterized the volatile fraction of different clinical matrices (i.e., bronchoalveolar lavage (BAL) and blind bronchial aspirate (BBA)). Due to the complexity of the mixture and high dynamic range of the concentrations, we applied headspace solid phase microextraction (HS-SPME) combined with comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC-TOFMS) to obtain a comprehensive overview of the sample headspace composition. Following the analytical step, we applied various univariate and multivariate statistical methods (e.g. random forest, principal component analysis, and hierarchical cluster analysis) in order to extract required information from the data. Based on the composition of the volatile fraction, we were able to differentiate between BAL and BBA with a classification accuracy of 88.4 %. Furthermore, we could correctly distinguish between individuals with active respiratory infections and those without infection with a 72.2 % classification accuracy. In some cases, it was also possible to differentiate between pathogens at the species level. These results are preliminary evidence to suggest the possibility of detecting infections in these patient without the use of time-consuming culture techniques. [less ▲]

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See detailSniffing Out the Hypoxia Volatile Metabolic Signature of Aspergillus fumigatus
Stefanuto, Pierre-Hugues ULg; Rees, Christiaan A.; Beattie, Sarah R. et al

Poster (2017, May)

Background: Aspergillus fumigatus is responsible for the life-threatening infection invasive aspergillosis (IA) that is associated with high mortality in immunocompromised individuals. Current diagnostics ... [more ▼]

Background: Aspergillus fumigatus is responsible for the life-threatening infection invasive aspergillosis (IA) that is associated with high mortality in immunocompromised individuals. Current diagnostics for IA are either highly invasive or suffer from inadequate sensitivity and/or specificity. Improvement of IA diagnostic assays requires a better understanding of fungal metabolism inside the host. The infection microenvironment becomes progressively depleted of oxygen during IA. Thus, metabolites associated with hypoxia metabolism may yield to novel diagnostic biomarkers. Here, we report on the volatile metabolites emitted from A. fumigatus batch cultures under normoxia and hypoxia conditions. Methods: A. fumigatus strain CEA10 was incubated in glucose minimal medium at 37 °C under either normoxia (21% O2, 0.04% CO2) or hypoxia (0.2% O2, 5% CO2) growth conditions. Volatile molecules from the supernatants of early (1 h) and late (8 h) cultures were collected using headspace solid-phase microextraction (HS-SPME) and analyzed using two-dimensional gas chromatography-time-of-flight mass spectrometry (GCxGC-TOFMS). Results: We identified 10 volatile compounds that are significantly more abundant in late hypoxia cultures compared with all other experimental conditions. Among these compounds, we identified ethanol and acetaldehyde, which are known to result from hypoxia metabolism of glucose by A. fumigatus. In addition, we detected 2-propanol, which can be generated by the reduction of acetone via alcohol dehydrogenase, as well as 2,3-butanedione (diacetyl) and 3-hydroxy-2-butanone (acetoin), which results from the catabolism of acetolactate. Transcriptomic data collected from normoxia and hypoxia cultures validates our volatilomic findings through the identification of putative catabolic pathways that are upregulated during hypoxia growth. Diacetyl is known to be produced by bacteria as a pH-neutral fermentative byproduct to prevent lethal acidification, and we speculate that A. fumigatus may use the same pathway. Conclusion: The composition of A. fumigatus’ volatile metabolome changes according to the oxygen tension in the environment. We measured hypoxia-associated compounds, ethanol and acetaldehyde which have been previously identified as byproducts of hypoxia metabolism in this organism. 2-propanol, 2, 3-butanedione and 3-hydroxy-2-butanone represent novel metabolites that suggests the existence of other catabolic pathways activated in A. fumigatus under hypoxia growth conditions. [less ▲]

Detailed reference viewed: 36 (2 ULg)