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See detailThe Chemistry of New Garlic-Derived Organosulfur Compounds and the Molecular Basis of Olfaction »
Dethier, Bérénice ULg

Doctoral thesis (2016)

Garlic is a very popular condiment that has been used around the world for centuries. It is also a source of a remarkably extensive range of organosulfur compounds, whose chemistry is the focus of this ... [more ▼]

Garlic is a very popular condiment that has been used around the world for centuries. It is also a source of a remarkably extensive range of organosulfur compounds, whose chemistry is the focus of this thesis. The central reaction in formation of these compounds is the enzymatic cleavage of alk(en)yl cysteine sulfoxides by alliinases, which leads to sulfenic acids. The latter can then undergo condensation and rearrangement into various organosulfur compounds. Three aspects of the chemistry of garlic have been investigated in this thesis. First, little studied, minor organosulfur compounds in extracts of freshly chopped garlic were studied. These higher molecular weight compounds (MW 150–550) can be conveniently studied using state-of-the-art Liquid Chromatography-Mass Spectrometry (LC-MS) and Direct Analysis in Real Time-Mass Spectrometry (DART-MS) techniques. Novel garlic-derived compounds were studied and the structure of one representative compound containing a five-membered thiolane ring, ajothiolane, was determined by spectroscopic methods, using synthetic analogues as spectroscopic standards. The fate of compounds in a garlic extract over time was also studied, since the new, higher mass sulfur compounds are slowly formed by rearrangement of smaller metabolites a few days after maceration of the garlic. A second part of this thesis provides hands-on methods for the analysis and preparation of key garlic metabolites. The isolation and/or synthesis of alliin, alliinase and vinyldithiins have been optimized, and are proposed as turnkey procedures for future work. Finally, in an effort to explain the unique odor of garlic-related thiols and sulfides (in garlic breath, sweat, etc.), the interactions between odorants and olfactory receptors have been studied. Work described in this thesis contributed to this larger project by designing and synthesizing model macrocyclic odorants to resolve the mechanism of olfaction at the receptor level. The conclusions, arguing against the plausibility of the so-called “vibration theory of olfaction”, have been published as a foundation for future work on olfactory detection of thiols and other sulfur-containing compounds. [less ▲]

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See detailChemistry of silica at different concentrations of non-ionic surfactant solutions: Effect of pH of the synthesis gel on the preparation of mesoporous silicas
Léonard, Alexandre ULg; Blin, J. L.; Jacobs, P. A. et al

in Microporous and Mesoporous Materials (2003), 63(1-3), 59-73

Ordered and disordered mesoporous silicas have been synthesized through an assembly of non-ionic decaoxyethylene cetyl ether [C 16(EO) 10] and a tetramethoxysilane silica source by variation of the pH ... [more ▼]

Ordered and disordered mesoporous silicas have been synthesized through an assembly of non-ionic decaoxyethylene cetyl ether [C 16(EO) 10] and a tetramethoxysilane silica source by variation of the pH value of the synthesis gel. The structure, texture and morphology of the mesoporous silicas, synthesized with concentrated and diluted surfactant solutions, have been discussed from the perspective of silica's chemistry upon a variation of pH values of the synthesis gel (micellar solution). With concentrated surfactant solutions (50 wt%), disordered compounds are obtained in a range of pH from 2.0 to 7.0 (micellar solution). As the pH increases, however, the pore size distributions (PSD) become broader and bimodality appears due to the micelle-templated silica (MTS) mesopores and openings arising from silica dissolution-reprecipitation processes. Also, the MTS pores expand due to a change in conformation of the surfactant hydrophilic head upon pH increase. On the other hand, diluted surfactant solutions (10 wt%) lead to ordered materials in a pH range from 2.0 to 7.0 (synthesis gel). The PSD remain very narrow but interparticular porosity appears and the morphologies undergo deep changes from toroids, gyroids and ropes to aggregates of very small particles with increasing pH. © 2003 Elsevier Inc. All rights reserved. [less ▲]

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See detailChemo- and enantio-selective method for the analysis of amino acids by capillary electrophoresis with in-capillary derivatization.
Fradi, Ines ULg; Servais, Anne-Catherine ULg; Lamalle, Caroline ULg et al

in Journal of Chromatography. A (2012), 1267

A novel dual chiral CE method was developed for the separation of l- and d-amino acids (AAs), using in-capillary derivatization with 9-fluoroenylmethyl chloroformate (FMOC). Firstly, using pre-column ... [more ▼]

A novel dual chiral CE method was developed for the separation of l- and d-amino acids (AAs), using in-capillary derivatization with 9-fluoroenylmethyl chloroformate (FMOC). Firstly, using pre-column derivatization, the enantioseparation of FMOC-AAs was optimized according to the nature of cyclodextrins (CD). A background electrolyte (BGE) composed of 30mM beta-CD, 30mM octakis(2,3-dihydroxy-6-O-sulfo)-gamma-CD (OS-gamma-CD), 40mM tetraborate and 15% isopropanol (IPA) was selected and led to 17 baseline resolved pairs (R(s)=1.7-5.8) and two partially resolved pairs (Lys, R(s)=0.5 and Arg, R(s)=1.2). Experimental conditions for in-capillary derivatization were then optimized. Several parameters, such as mixing voltage and time, concentration of labeling solution and the length of the spacer plug were studied. The optimal conditions for in-capillary derivatization procedure were obtained using successive hydrodynamic injections (30mbar) of AAs for 2s, borate buffer for 4s and 10mM FMOC solution for 6s, followed by a mixing at 3kV for 72s and wait time of 1min. Moreover, a particular attention was paid to improve separation chemoselectivity. The effect on stereoselectivity and chemoselectivity of different factors, such as decrease of pH and tetraborate concentration and the addition of sodium dodecyl sulfate (SDS), was investigated using the in-capillary derivatization procedure. The best separation of a standard mixture of ten AA racemates was observed using a BGE containing 30mM beta-CD, 30mM OS-gamma-CD, 25mM SDS, 40mM sodium tetraborate and 17% IPA. [less ▲]

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See detailChemo-mechanical interactions in clay: a correlation between clay mineralogy and Atterberg limits
Schmitz, R. M.; Schroeder, Christian ULg; Charlier, Robert ULg

in Applied Clay Science (2004), 26(1-4), 351-358

Among some few others tests, the evaluation of the Atterberg limits is a very basic soil mechanical test allowing a first insight into the chemical reactivity of clays. Basically, the liquid limit and the ... [more ▼]

Among some few others tests, the evaluation of the Atterberg limits is a very basic soil mechanical test allowing a first insight into the chemical reactivity of clays. Basically, the liquid limit and the plasticity index are highly and mainly influenced by the ability of clay minerals to interact with liquids. In this contribution, a correlation between the Atterberg limits and clay mineralogy is proposed. This correlation increases the understanding between clay mineralogists and engineers in soil mechanics; additionally a wealth of information in clay mineralogy literature is now available to predict the mechanical behaviour of clays via index tests. (C) 2003 Elsevier B.V. All rights reserved. [less ▲]

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See detailChemo-mechanical interactions in clay: are the Atterberg limits useful?
Schmitz, R.; Hiligsmann, M.; Schroeder, Christian ULg et al

in Clays in Natural and Engineered Barriers of Radioactive Waste Confinement - Int. Meeting Reims (2002, December)

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See detailChemo-Mechanical Modelling of Soil or Rock Degradation
Charlier, Robert ULg; Boukpeti, N.

in 2nd Int. Symposium on Continuous and Discontinuous Modelling of Cohesive Frictional Materials. (2004, September)

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See detailChemoautotrophy and anoxygenic photosynthesis within the water column of a large meromictic tropical lake (Lake Kivu, East Africa)
Morana, Cédric; Roland, Fleur ULg; Crowe, Sean A. et al

in Limnology and Oceanography (2016)

We quantified chemoautotrophic and anoxygenic photosynthetic microbial production in the water column of Lake Kivu, a permanently stratified tropical lake situated amidst volcanic activity, and aimed to ... [more ▼]

We quantified chemoautotrophic and anoxygenic photosynthetic microbial production in the water column of Lake Kivu, a permanently stratified tropical lake situated amidst volcanic activity, and aimed to identify the microorganisms involved in these processes through the analysis of their phospholipid fatty acid (PLFA) content and stable isotope (13C) labelling of PLFA in a set of incubation experiments. Data demonstrate the existence of a biogeochemically active chemoautotrophic bacterial community in the redoxcline of Lake Kivu (50–70 m). PLFA data indicate that the bacterial communities are structured vertically in the water column, with a large dissimilarity between the oxic and anoxic waters. Maximum volumetric dark CO2 fixation rates measured in Lake Kivu were in the same range as values reported from H2S-rich marine redoxclines, such as the Black and Baltic Seas, and the Cariaco Basin. Similarly, maximal chemoautotrophic activities in Lake Kivu were observed in sulfidic waters, just below the oxycline. Anoxygenic photosynthetic production was never observed in the main basin of Lake Kivu. However, anoxygenic phototrophs largely dominated CO2 fixation in the illuminated redoxcline of Kabuno Bay, a shallower ferruginous sub-basin. Overall, this study supports the idea that chemoautotrophs and/or anoxygenic photoautotrophs might play an important role in the flow of carbon and energy in permanently stratified tropical ecosystems. In Lake Kivu, these processes significantly contribute to organic matter biosynthesis and exert an indirect control on oxygenic photoautotrophs by shortcircuiting the vertical transport of nutrients to the illuminated and oxygenated surface waters. [less ▲]

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See detailCHEMOKINE (CC-MOTIF) LIGAND 2 AS A PROGNOSTIC SERUM MARKER IN CANINE IDIOPATHIC PULMONARY FIBROSIS
Roels, Elodie ULg; Holopainen, S.; Teske, Erik ULg et al

Poster (2015, September 11)

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See detailLes chémokines et leurs récepteurs : rôle dans les infections virales et dans les pathologies cancéreuses
Burteau, C.; Willems, Luc ULg; Kettmann, Richard ULg

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2007)

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See detailChemometric tools for NIRS and NIR hyperspectral imaging
Dale, Laura ULg; Thewis, André ULg; Rotar, Ioan et al

in Bulletin of USAVM Cluj Napoca, Agriculture (2012, September 27), 69(1), 70-76

Nowadays in agriculture, new analytical tools based on spectroscopic technologies are developed. Near Infrared Spectroscopy (NIRS) is a well known technology in the agricultural sector allowing the ... [more ▼]

Nowadays in agriculture, new analytical tools based on spectroscopic technologies are developed. Near Infrared Spectroscopy (NIRS) is a well known technology in the agricultural sector allowing the acquisition of chemical information from the samples with a large number of advantages, such as: easy to use tool, fast and simultaneous analysis of several components, non-polluting, non-invasive and non destructive technology, and possibility of online or field implementation. Recently, NIRS system was combined with imaging technologies creating the Near Infrared Hyperspectral Imaging system (NIR-HSI). This technology provides simultaneously spectral and spatial information from an object. The main differences between NIR-HSI and NIRS is that many spectra can be recorded simultaneously from a large area of an object with the former while with NIRS only one spectrum was recorded for analysis on a small area. In this work, both technologies are presented with special focus on the main spectrum and images analysis methods. Several qualitative and quantitative applications of NIRS and NIR-HSI in agricultural products are listed. Developments of NIRS and NIR-HSI will enhance progress in the field of agriculture by providing high quality and safe agricultural products, better plant and grain selection techniques or compound feed industry’s productivity among others. [less ▲]

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See detailChemometrics and chromatographic fingerprints to discriminate and classify counterfeit medicines containing PDE-5 inhibitors.
Deconinck, Eric; Sacre, Pierre-Yves ULg; Courselle, Patricia et al

in Talanta (2012), 100

Chromatographic fingerprints recorded for a set of genuine and counterfeit samples of Viagra® and Cialis® were evaluated for their use in the detection and classification of counterfeit samples of these ... [more ▼]

Chromatographic fingerprints recorded for a set of genuine and counterfeit samples of Viagra® and Cialis® were evaluated for their use in the detection and classification of counterfeit samples of these groups of medicines. Therefore several exploratory chemometric techniques were applied to reveal structures in the data sets as well as differences among the samples. The focus was on the differentiation between genuine and counterfeit samples and on the differences between the samples of the different classes of counterfeits as defined by the Dutch National Institute for Public Health and the Environment (RIVM). In a second part the revealed differences between the samples were modelled to obtain a predictive model for both the differentiation between genuine and counterfeit samples as well as the classification of the counterfeit samples. The exploratory analysis clearly revealed differences in the data for the genuine and the counterfeit samples and with projection pursuit and hierarchical clustering differences among the different groups of counterfeits could be revealed, especially for the Viagra® data set. For both data sets predictive models were obtained with 100% correct classification rates for the differentiation between genuine and counterfeit medicines and high correct classification rates for the classification in the different classes of counterfeit medicines. For both data sets the best performing models were obtained with Least Square-Support Vector Machines (LS-SVM) and Soft Independent Modelling by Class Analogy (SIMCA). [less ▲]

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See detailChemometrics and vibrational spectroscopy for the detection of melamine levels in milk
Fernandez Pierna, Juan; Vincke, Damien; Baeten, Vincent et al

Poster (2016, January 19)

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See detailChemometrics methods for the identification and the monitoring of an odour in the environement with an electronic nose
Nicolas, Jacques ULg; Romain, Anne-Claude ULg; Maternova, J.

in Ramirez-Silva, Maria Theresa (Ed.) Sensors and chemometrics (2001)

The purpose of the paper is to briefly review some researches regarding the adaptation of the electronic nose principle to recognise some malodour sources in the environment, if possible directly in the ... [more ▼]

The purpose of the paper is to briefly review some researches regarding the adaptation of the electronic nose principle to recognise some malodour sources in the environment, if possible directly in the field, and to monitor the odour intensity continuously. Research aims at improving the portability and the user-friendliness of the instrument, together with testing what kind of signal may be used to monitor the odour. A laboratory-made electronic nose, constituted of an array of tin-oxide sensors, is used in different configurations. The ambient air is either sampled around environmental sources (landfill, urban waste composting facilities, …), or directly transferred into the sensor chamber in the field. Two main options are considered : firstly, identifying the source of odour in the background and among interfering odours and, secondly, when the malodour is recognised, trying to monitor it continuously in order, for example, to assess the nuisance or to control an odour abatement system. Chemometrics methods are generally used for both purposes. They provide quick answers and allow to evaluate the relationships between variables and between observations at a glance. They are applied on the sensor signals, eventually preprocessed by a suitable algorithm. Non-supervised analyses, such as Principal Component Analysis (PCA), provide basically a performance evaluation of the system during the development phase. On the contrary, supervised analyses, such as Discriminant Analysis (DA), or some Neural Networks algorithms are quite appropriate to make a reliable recognition in real time, when the system is developed. To predict the odour intensity, different techniques are tested : either using only one of the sensor elements, or applying different chemometrics techniques, such as Multilinear Regression (MLR) on the original measured sensor signals, Principal Component Regression (PCR), or Partial Least Squares regression (PLS). The latter seems to be the most adapted model for the intensity prediction. [less ▲]

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See detailChemoresistance to Valproate Treatment of Bovine Leukemia Virus-Infected Sheep; Identification of Improved HDAC Inhibitors
Gillet, Nicolas ULg; Vandermeers, Fabian ULg; De Brogniez, Alix ULg et al

in Pathogens (2012), (2012-1), 65-82

We previously proved that a histone deacetylase inhibitor (valproate, VPA) decreases the number of leukemic cells in bovine leukemia virus (BLV)-infected sheep. Here, we characterize the mechanisms ... [more ▼]

We previously proved that a histone deacetylase inhibitor (valproate, VPA) decreases the number of leukemic cells in bovine leukemia virus (BLV)-infected sheep. Here, we characterize the mechanisms initiated upon interruption of treatment. We observed that VPA treatment is followed by a decrease of the B cell counts and proviral loads (copies per blood volume). However, all sheep eventually relapsed after different periods of time and became refractory to further VPA treatment. Sheep remained persistently infected with BLV. B lymphocytes isolated throughout treatment and relapse were responsive to VPA-induced apoptosis in cell culture. B cell proliferation is only marginally affected by VPA ex vivo. Interestingly, in four out of five sheep, ex vivo viral expression was nearly undetectable at the time of relapse. In two sheep, a new tumoral clone arose, most likely revealing a selection process exerted by VPA in vivo. We conclude that the interruption of VPA treatment leads to the resurgence of the leukemia in BLV-infected sheep and hypothesize that resistance to further treatment might be due to the failure of viral expression induction. The development of more potent HDAC inhibitors and/or the combination with other compounds can overcome chemoresistance. These observations in the BLV model may be important for therapies against the related Human T-lymphotropic virus type 1. [less ▲]

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See detailA Chemoselective Ligation For The Synthesis Of Amino Acid Derivatives Of Virginiamycin M-1
Nott, Katherine ULg; Dufour, Samuel; Gossele, Francis et al

in Tetrahedron Letters (2005), 46(43),

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See detailChemotaxis-Promoting and Adhesion Properties of Human Tonsillar Follicular Dendritic Cell Clusters
Bouzahzah, F.; Antoine, Nadine ULg; Simar, Léon ULg et al

in Research in Immunology (1996), 147(3, Mar-Apr), 165-73

Lymph follicles are globular and compact due to aggregation of lymphoid cells on follicular dendritic cells (FDC). To probe the mechanisms underlying this accumulation of cells, we analyse here the role ... [more ▼]

Lymph follicles are globular and compact due to aggregation of lymphoid cells on follicular dendritic cells (FDC). To probe the mechanisms underlying this accumulation of cells, we analyse here the role played by FDCs in attracting and binding cells. FDCs prepared from human tonsils by mild separation techniques appeared in the form of clusters (FDC clusters), where, via cytoplasmic extensions, they enveloped lymphoid cells. Using Boyden's chambers, we demonstrated that these FDC clusters produced one or more chemoattractants capable of inducing chemotaxis of lymphoid cells. Supernatants of FDC cluster cultures also exerted a chemotaxis-promoting effect. FDC clusters induced true chemotaxis, not merely chemokinesis due to cell activation. They secreted a substance or substances that stuck to the substrate (a cellulose filter) and thus induced haptotaxis. B as well as T cells were attracted, but B cells apparently required the presence of T cells to respond fully to the chemoattractant(s). Subtypes of B cells (IgD+ and IgD-) and T cells (CD4+, CD8+, CD57+ AND CD57-) were tested and all were attracted. Since purified lymphoid cells did not induce these phenomena, FDCs were suspected to do so. FDCs have been shown to establish contact with lymphoid cells. Here we have determined that CD4+ T cells adhere in greater number to FDC clusters than do CD8+ T cells. We thus propose that FDCs specifically contribute to construction of lymph follicles by attracting and determining their cell composition. [less ▲]

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See detailChemotherapy options for patients suffering from heavily pretreated metastatic breast cancer.
Jerusalem, Guy ULg; RORIVE, Andrée ULg; COLLIGNON, Joëlle ULg

in Future oncology (London, England) (2015), 11(12), 1775-89

ABSTRACT The identification of additional chemotherapy agents for anthracycline- and taxane-pretreated advanced breast cancer (ABC) is an urgent medical need. Single agent chemotherapy is most times ... [more ▼]

ABSTRACT The identification of additional chemotherapy agents for anthracycline- and taxane-pretreated advanced breast cancer (ABC) is an urgent medical need. Single agent chemotherapy is most times administered because combined therapy is only associated with modest, if any, improvement in median progression-free survival. Randomized trials failed to show overall survival benefit compared with single agent chemotherapy. We hope to modify the natural history of ABC by the consecutive use of treatments with documented activity in heavily pretreated patients. Quality of life remains an important end point as cure is in general not possible. We first review the activity of the approved and the most frequently used agents in heavily pretreated ABC. Thereafter, the potential role and safety profile of etirinotecan pegol is discussed given the results recently released of a Phase III trial comparing this agent to Treatment of Physician's Choice. [less ▲]

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See detailChemotherapy-driven dysbiosis in the intestinal microbiome
Montassier, E.; Gastinne, T.; Vangay, P. et al

in Alimentary Pharmacology & Therapeutics (2015)

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