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See detailNew alginate-chitosan hydrogel to repair cartilage
Henrotin, Yves ULg

Conference (2012, April 18)

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See detailInfluence of protein context on the propensity of polyglutamine tracts to induce protein aggregation into amyloid fibrils
Huynen, Céline ULg

Poster (2012, April 18)

Nine neurodegenerative diseases, referred to as polyglutamine diseases, are associated with nine proteins containing an expanded polyglutamine (polyQ) tract. PolyQ tracts are encoded by a repetition of ... [more ▼]

Nine neurodegenerative diseases, referred to as polyglutamine diseases, are associated with nine proteins containing an expanded polyglutamine (polyQ) tract. PolyQ tracts are encoded by a repetition of the CAG codon in the corresponding genes, and are present in proteins of healthy people. They are however pathogenic when their length, due to mutations, becomes higher than a threshold generally comprised between 35 and 45Q. Such pathogenic tracts trigger the aggregation of the proteins into amyloid-like aggregates that could play an important role in the disease. It is therefore necessary to investigate at a molecular level the aggregation process of polyQ proteins. Since proteins associated with polyQ diseases are generally big and relatively insoluble, they are difficult to produce and manipulate. We have therefore decided to study the aggregating properties of polyQ proteins by designing and characterizing model proteins made of a well-characterized host protein, the β-lactamase BlaP, and polyQ tracts of different lengths (23 to 79Q) inserted at position 197 of BlaP. The aggregating properties of these BlaP chimeras recapitulate those of proteins associated with polyQ diseases. We indeed observed that there is a minimal number of glutamines (threshold) required for chimeras aggregation into amyloid-like fibrils and that the kinetics of aggregation are faster with longer glutamine repeats. Most importantly, the value of the threshold for amyloid-like fibril formation seems to critically depend on the structural integrity of BlaP and thus on the constraints applied to the polyQ tract. In the present work, we investigate more deeply the role of the protein context and the role of oligomers in the process of aggregation of BlaP chimeras. This study is mainly based on the use of two techniques: the quartz crystal microbalance with dissipation (QCM-D) in combination with atomic force microscopy (AFM), and the dynamic light scattering (DLS). Preliminary QCM-D results indicate that in native condition there is a minimal number of glutamines required for the elongation of BlaP197(Gln)79 fibrils by BlaP chimeras. This threshold is different to that observed for the aggregation monitored in solution in absence of seed. Most interestingly it corresponds to the threshold observed in denaturing conditions. These observations suggest that the conformation of BlaP is the limiting step for amyloid fibril formation by interfering with the nucleation step. Preliminary DLS experiments indicate that the oligomers formed by BlaP197(Gln)79 in native condition are on the pathway of amyloid fibril formation and could act as aggregation nuclei. [less ▲]

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See detailMolecular biomimetics applied to medical devices
Van de Weerdt, Cécile ULg; Vreuls, Christelle ULg; Genin, Alexis ULg et al

Poster (2012, April 18)

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See detail1-84 PTH and KDIGO Guidelines
CAVALIER, Etienne ULg

Conference (2012, April 18)

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See detailNew Advances for In Situ Protein Identification by MALDI In-Source Decay FTMS Imaging
Calligaris, David ULg; Zimmerman, Tyler ULg; Debois, Delphine ULg et al

Poster (2012, April 18)

MALDI imaging mass spectrometry has proven to be effective for the discovery and the monitoring of disease-related proteins. With this technique a molecular analysis could be performed directly from ... [more ▼]

MALDI imaging mass spectrometry has proven to be effective for the discovery and the monitoring of disease-related proteins. With this technique a molecular analysis could be performed directly from tissue sections in the region of the diseased area. The use of in-source decay (ISD), allowing fast and reliable sequences assignments of proteins termini, has proven to be a crucial tool for proteins identification in solution and tissue slices. However, it is necessary to develop additional tools that allow unambiguous assignment of proteins sequences in complex tissue slices. The development of bioinformatic tools and the use of ultra-high mass resolution and high mass accuracy of Fourier transform ion-cyclotron (FTICR) mass spectrometry are ideal for this purpose. In this study, we show that FTICR mass spectrometry combined with data filtering with a software that subtracts matrix peaks aid protein identification. All measurements were carried out on a SolariX FTMS (9.4 Tesla) equipped with a Dual Source with a smartbeamTMII laser (Bruker Daltonics). Mouse brain tissue slices of 14 µm thickness were rinsed to obtain optimal sensitivity and high-quality ions. Before matrix application, a spot of myelin was deposited near mouse brain. 1,5-Diaminionaphtalene was sprayed using an ImagePrep (Bruker Daltonics). Results were interpreted using BioToolsTM 3.2 in combination with MascotTM (Matrix Science) for ISD spectra and FlexImagingTM 3.0 for MALDI-ISD imaging experiments. Matrix peaks were subtracted using an in-house written Java code that sequentially scans all peak lists from acquired spectra against the DAN mass list. Then, another Java code allows to create 2D ion images at selected m/z ratios. The studies were carried out by MALDI-ISD imaging to create interest on FTICR mass spectrometer for proteins identification in the field of biomarkers characterization. It is demonstrated that protein ISD leads to the same pattern of fragmentation observed during MALDI-TOF analyzes. Fragmentation generates cn- and zn-series ions of myelin in presence of DAN. The internal calibration of all the data provides a mass accuracy neighboring 2.5 ppm over the m/z range of interest (300-2500 Da) and a mass resolution of 70000 at m/z 400 Da. It allows the assignment of ISD fragments of proteins in the low mass range (m/z between 300 and 900) that is unambiguously validated by the “ISD signal” recorded from the spots of pure protein solution (myelin) near tissue slice. Moreover, the use of our software “cleans” MS imaging data by reducing/eliminating MALDI matrix peaks that are isobaric to an analyte peak. Novel aspect This study evidences the main input of FTICR mass spectrometer for pathologies diagnosis based on biomarkers localization and identification by MALDI-ISD imaging. [less ▲]

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See detailDegradation of recombinant IgG by root-secreted proteases of Arabidopsis thaliana and Nicotiana tabacum
Désiron, Carole ULg; Lallemand, Jérôme ULg; Périlleux, Claire ULg et al

Poster (2012, April 18)

Plants are promising hosts for the production of complex recombinant pharmaceuticals, such as antibodies (mAbs), because they offer an inexpensive and safer alternative to traditional production systems ... [more ▼]

Plants are promising hosts for the production of complex recombinant pharmaceuticals, such as antibodies (mAbs), because they offer an inexpensive and safer alternative to traditional production systems. The plant-based production of mAbs, which are multimeric glycoproteins, require their targeting to the secretory pathaway where they are properly folded and matured. However, co-secretion of endogenous proteases, which can represent up to 10% of the extracellular proteins (secretome), is known to significantly alter the yield and quality of secreted mAbs. In this study, we analyzed the proteolytic activities in root-secretome of Arabidopsis thaliana and Nicotiana tabacum. Root-secretomes were recovered by salt extraction and the protease activity was assayed in vitro or by zymography, in a range of pH. The relative contribution of protease classes was evaluated with specific inhibitors. [less ▲]

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See detailNeuropeptides and endogenous opioids expression during silent chronic inflammation
Chavarria Bolanos, D; de Jesus Pozos Guillén, A; Grandfils, Christian ULg et al

Poster (2012, April 18)

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See detailSynthesis and evaluation of boronic acids as inhibitors of Penicillin Binding Proteins of classes A, B and C
Zervosen, Astrid ULg; Sauvage, Eric ULg; Bouillez, André ULg et al

Poster (2012, April 18)

The widespread use of beta-lactam antibiotics has lead to the worldwide appearance of drug-resistant strains. Bacteria have developed resistance to beta-lactams by three main mechanisms: the production of ... [more ▼]

The widespread use of beta-lactam antibiotics has lead to the worldwide appearance of drug-resistant strains. Bacteria have developed resistance to beta-lactams by three main mechanisms: the production of beta-lactamases that catalyze hydrolysis of beta-lactams, the production of low-affinity, drug resistant Penicillin Binding Proteins (PBPs) and the over expression of resistant PBPs. PBPs are interesting targets because they catalyse the last steps of the biosynthesis of peptidoglycan, which is unique in bacteria and has no mammalian analogs, outside the cytoplasmic membrane. Various non-ß-lactam inhibitors of PBPs have been developed with the objective of attempting to stall the development of ß-lactam resistance. Boronic acids are potent beta-lactamase inhibitors and have been shown to display some specificity for soluble transpeptidases and PBPs, but their potential as inhibitors of the latter enzymes is yet to be widely explored. Recently, a (2, 6-dimethoxybenzamido)methylboronic acid was identified as being a potent inhibitor of Actinomadura sp. R39 transpeptidase (IC50: 1.3 µM). Here, we will discuss the synthesis of a number of acylaminomethylboronic acids, analogs of (2, 6-dimethoxybenzamido)methylboronic acid, and their potential as inhibitors of PBPs. Several boronic acids of this library were able to inhibit PBPs of classes A, B and C from penicillin sensitive strains. Thus (2-nitrobenzamido)methylboronic acid was identified as a good inhibitor of class A PBP (PBP1b from S. pneumoniae, IC50 = 26 µM), class B PBP (PBP2xR6 from S. pneumoniae, IC50 = 138 µM) and class C PBP (R39 from Actinomadura sp., IC50 = 0.6 µM). Crystal structures of complexes of R39 and PBP1b with boronic acid analogs of our library have already been solved and allowed an interpretation of results. We believe that this work opens new avenues towards the development of molecules that will inhibit PBPs, and eventually display bactericidal effect, on distinct bacterial species. [less ▲]

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See detailPossible intracellular effect of the new water-soluble form of curcumin (NDS27) on the oxidant response of stimulated neutrophils
Derochette, Sandrine ULg; Mouithys-Mickalad, Ange ULg; Deby-Dupont, Ginette et al

Poster (2012, April 18)

Neutrophils (PMNs) are involved in host defense against infections through the production of reactive oxygen species (ROS) to kill pathologic agents. But, an excessive ROS production, called “oxidative ... [more ▼]

Neutrophils (PMNs) are involved in host defense against infections through the production of reactive oxygen species (ROS) to kill pathologic agents. But, an excessive ROS production, called “oxidative stress” is associated with tissue damages and development of chronic or acute inflammatory diseases. PMNs are prime therapeutic targets to control inflammatory events associated to ROS production. Nowadays, there is a growing interest for the use of polyphenolic molecules to modulate the inflammatory response. The aim of this work was to study the antioxidant effect of NDS27 (1), a new highly water-soluble form of the polyphenolic molecule curcumin, on in vitro stimulated equine PMNs. NDS27 (10-6 to 10-4 M) was pre-incubated with cells and eliminated before their activation. The ability of NDS27 to enter into the cells was checked by HPLC from the cellular extracts. The intracellular ROS production by phorbol myristate acetate (PMA) stimulated PMNs was measured by fluorescence using 2’,7’-dichlorofluorescin diacetate. Lucigenin dependent chemiluminescence was used to measure extracellular ROS production. Additionally, the effect of NDS27 was tested on the activity of myeloperoxidase (MPO), a hemic enzyme contributing to the oxidant response of neutrophils. The activity of the released MPO by cytochalazine B (CB) and N-formyl-methionyl-leucyl-phenylalanine (fMLP) stimulated PMNs was measured by SIEFED (“Specific Immunologic Extraction Followed by Enzymatic Detection”) (2). The HPLC results showed that NDS27 enters into PMNs and interacts with their membrane. NDS27 significantly and dose-dependently inhibited the ROS production in neutrophils without affecting their viability. Likewise, the activity of MPO released by PMNs was lowered by NDS27. Overall, our findings demonstrate that the membrane of neutrophils is permeable to NDS27 or interacts with the drug, suggesting that its inhibitory effect on ROS production is mainly associated to an intracellular effect probably by acting on the enzymes implied in respiratory burst like NADPH oxidase and MPO. The modulatory effect of NDS27 towards the oxidant activity of cells involved in immune and inflammatory response open therapeutic perspectives to control equine or human pathologies with excessive inflammatory reactions. 1. Neven et al. 2011, Patent Application Publication: US2011/0257126 A1 2. Serteyn et al. 2005, European Patent Specification : EP1711817 B1 [less ▲]

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See detailInnovative multilayered nanofibers for wound dressing application
Croisier, Florence ULg; Detrembleur, Christophe ULg; Jérôme, Christine ULg

Poster (2012, April 18)

Chitosan is a natural polymer derived from the chitin of crustacean or mushroom shells, that intrinsically presents haemostatic, mucoadhesive, antimicrobial and immunostimulant properties. This ... [more ▼]

Chitosan is a natural polymer derived from the chitin of crustacean or mushroom shells, that intrinsically presents haemostatic, mucoadhesive, antimicrobial and immunostimulant properties. This polysaccharide has shown a great potential for biomedical and pharmaceutical applications, on account of its remarkable compatibility with physiological medium. Besides, it is degraded in a physiological environment into non-toxic products, which make chitosan an outstanding candidate for short- to medium-term applications. In this respect, nanometric fibers are highly interesting as their assembly mimics the skin extracellular matrix structure. Such nanofibrous materials can be prepared by electrospinning (ESP). This technique uses a high voltage to create an electrically charged jet of polymer solution or melt which leads to fibers formation. Depending on the polymer characteristics (a.o. molecular weight, solution viscosity and conductivity) and processing conditions (electric potential, distance between syringe-capillary and collection plate, concentration, flow rate), polymer fibers ranging from nanometers to a few microns in diameter can be obtained and subsequently used as potential scaffolds, a.o. to form a temporary, artificial extracellular matrix. In the present study, electrospinning technique was combined with layer-by-layer deposition method (LBL) - a well-known method for surface coating, based on electrostatic interactions - in order to prepare multilayered chitosan-based nanofibers. The antibacterial properties of the obtained material were then assessed, and the presence of a multilayered deposit was confirmed by several techniques. (Future) possibilities for valorization: These multilayered chitosan-based nanofibers present great prospects for the preparation of new biomedical scaffolds - such as wound dressings that could improve skin regeneration. [less ▲]

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See detailWhat is new in anemia treatment in CKD since 2010?
Krzesinski, Jean-Marie ULg

Conference (2012, April 18)

•Partial correction (Hb in the range of 10-11.5 g/dL) of CKD-related anemia appears a safer strategy during the last 5y. So recommendation is to start ESA only when Hb <10 and to avoid too high ESA dose ... [more ▼]

•Partial correction (Hb in the range of 10-11.5 g/dL) of CKD-related anemia appears a safer strategy during the last 5y. So recommendation is to start ESA only when Hb <10 and to avoid too high ESA dose (CE DOSE study ongoing in HD)! •Identify resistant patients and try to improve it. •Importance of adequate iron management and of hepcidin role in the all-mortality risk in CKD. Newer strategies for correcting anemia are currently explored [less ▲]

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See detailClinicopathologic significance of DNA methyltransferase 1, 3a, and 3b overexpression in Tunisian breast cancers.
Ben Gacem, Riadh; Hachana, Mohamed Ridha ULg; Ziadi, Sonia et al

in Human Pathology (2012)

DNA methyltransferase 1, 3a, and 3b affect DNA methylation, and it is thought that they play an important role in the malignant transformation of various cancers. The current study was designed to analyze ... [more ▼]

DNA methyltransferase 1, 3a, and 3b affect DNA methylation, and it is thought that they play an important role in the malignant transformation of various cancers. The current study was designed to analyze DNA methyltransferase expression by immunohistochemistry in a series of 94 Tunisian sporadic breast carcinomas. Results were correlated to clinicopathologic parameters and promoter methylation status of 8 tumor suppressor genes (BRCA1, BRCA2, RASSFA1, TIMP3, CDH1, P16, RARβ2, and DAPK). Overexpression of DNA methyltransferase 1, 3a, and 3b was detected in 46.8%, 32%, and 44.7% of cases, respectively. A significant correlation was found between DNA methyltransferase 1 overexpression and Scarff-Bloom-Richardson histologic grade III (P = .01). DNA methyltransferase 3a overexpression was significantly associated with menopausal status (P = .01), Scarff-Bloom-Richardson histologic grade III (P = .0001), estrogen (P = .04) and progesterone (P = .007) receptor negativity, and HER2 overexpression (P = .004). However, DNA methyltransferase 3a overexpression was found less frequently in the luminal A intrinsic breast cancer subtype (9.7%) than in luminal B (53%), HER2 (41%), and triple-negative (50%) subtypes (P = .001). DNA methyltransferase 3b overexpression shows significant correlation with promoter hypermethylation of BRCA1 (P = .03) and RASSFA1 (P = .04) and with the hypermethylator phenotype (more than 4 methylated genes, P = .01). These data suggest that overexpression of various DNA methyltransferases might represent a critical event responsible for the epigenetic inactivation of multiple tumor suppressor genes, leading to the development of aggressive forms of sporadic breast cancer. [less ▲]

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See detailPhysical Fitness and Mitochondrial Respiratory Capacity in Horse Skeletal Muscle
Votion, Dominique ULg; Gnaiger, Erich; Lemieux, Hélène et al

in PLoS ONE (2012), 7(4), 1-12

We applied high-resolution respirometry and multiple substrate-uncoupler-inhibitor titration protocols to study mitochondrial physiology in small (1.0–2.5 mg) permeabilized muscle fibres sampled from ... [more ▼]

We applied high-resolution respirometry and multiple substrate-uncoupler-inhibitor titration protocols to study mitochondrial physiology in small (1.0–2.5 mg) permeabilized muscle fibres sampled from triceps brachii of healthy horses. The present investigation on horse skeletal muscle has tested the methodology used to study mitochondrial function in muscle microbiopsies by high-resolution respirometry to define reference protocols for horses (from sampling procedure to data analysis). [less ▲]

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See detailMaterial Aspects of Bone Tissue Engineering
Ozhukil Kollath, Vinayaraj ULg; Cloots, Rudi ULg

Diverse speeche and writing (2012)

Bone tissue engineering is a highly studied topic in material science in the recent decades. Basic principles of chemistry and biology along with advanced material science techniques should be used in ... [more ▼]

Bone tissue engineering is a highly studied topic in material science in the recent decades. Basic principles of chemistry and biology along with advanced material science techniques should be used in order to elucidate the parameters which may influence the bone tissue growth on artificial implants. Progress has been made to an advanced level but still there is room for improvements. Especially in case of large bone defects, finding a ‘universal’ replacement implant is difficult. Patient specific data have to be taken in to account to get a good osteointegration. Metal and ceramic implants are commonly tested in case of large bone defects, but a good mimic of natural bone is hard due to various reasons. However fine tuning these materials and combination of these materials are finding good results. Addition of polymer materials in such implants is a recent effective attempt. Different combinations of these materials along with functionalisation using bioactive molecules make the bone tissue engineering nearly perfect. This presentation will discuss about the recent trends in the materials used in bone tissue engineering. [less ▲]

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See detailConstruire son langage, une nouvelle conception de l’acquisition langagière: données développementales et approche en pathologie langagière
Leroy, Sandrine ULg; Maillart, Christelle ULg

Scientific conference (2012, April 17)

Cette conférence traite des répercussions sur notre pratique logopédique d’une nouvelle conception du développement langagier. Celle-ci s’intéresse à la construction du langage oral chez l’enfant. Elle ... [more ▼]

Cette conférence traite des répercussions sur notre pratique logopédique d’une nouvelle conception du développement langagier. Celle-ci s’intéresse à la construction du langage oral chez l’enfant. Elle considère que l’enfant est l’acteur de son développement langagier ; il construit progressivement son langage à partir de ses propres productions antérieures. Cette nouvelle conception issue de la linguistique cognitivo-fonctionnelle s’oppose donc à la conception innéiste (ou générativiste) qui considère que l’enfant dispose de connaissances langagières innées. Cette approche constructiviste nous offre des perspectives théoriques et thérapeutiques très intéressantes pour étudier la pathologie langagière. Des données récentes récoltées auprès d’enfants tout-venant sont présentées. Par la suite, nous abordons plus spécifiquement la dysphasie. Nous tentons de comprendre comment ces théories permettent d'expliquer les difficultés langagières des enfants dysphasiques. Enfin, nous envisageons quels sont les éléments dont il faut tenir compte dans notre pratique logopédique, à la lumière de cette nouvelle conception développementale. [less ▲]

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See detailAnémies et insuffisance rénale : quoi de neuf?
Krzesinski, Jean-Marie ULg

Conference (2012, April 17)

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