Browsing
     by title


0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

or enter first few letters:   
OK
Peer Reviewed
See detailEngery-filtering transmission electron microscopy of biological specimens.
de Bruijn, W. C.; Sorber, C. W.; Gelsema, E. S. et al

in Scanning Microscopy (1993), 7(2), 693-708709

By energy-filtering transmission electron microscopy (EFTEM) electrons can be separated by their energy losses. An electron-energy filter, added to the microscope column allows the measurement of the ... [more ▼]

By energy-filtering transmission electron microscopy (EFTEM) electrons can be separated by their energy losses. An electron-energy filter, added to the microscope column allows the measurement of the energy distribution of transmitted electrons that have lost energy (< 2,000 eV, with an energy resolution of approximately 1 eV). These filtered electrons, recorded either as a spectrum or as an image, are composed of two parts superimposed on top of each other: (a) the unspecific energy-loss population (= the continuum) and (b) the specific element-related energy-loss population (= the edges). At the edges, electron data in spectra and images are mathematically processed, to obtain the desired element-related net-intensity values or images. These data are related to the total transmitted electron intensity, from the zero- and low-loss spectral region giving the relative spectralor image intensity rations ((S)R*x, (I)R*x), which can be related to the element concentration. The acquisition of the zero-loss and low-loss data is hampered by the restricted dynamic range of the TV camera. By improvements through the introduction of calibrated attenuation filters in the optical path to the TV-camera, more reliable values for (S)R*x and (I)R*x can be acquired. By addition of Bio-standards adjacent to the tissue, a "known" and "unknown" concentration of the element present in the same ultrathin section and the "bias" in the concentration estimation, can be obtained. Some practical examples are given for the estimation of the iron cencentration in siderosomes, boron in melasosomes and calcium in calcium oxalate monohydrate crystals. [less ▲]

Detailed reference viewed: 13 (0 ULg)
Full Text
See detailEnghien, rempart Saint-Christophe
Frankignoulle, Pierre ULg

in Frankignoulle, Pierre; Dawance, Sophie; Malherbe, Alain (Eds.) Habiter la Ville (2001)

Detailed reference viewed: 6 (0 ULg)
Full Text
Peer Reviewed
See detailEngineering a camelid antibody fragment that binds to the active site of human lysozyme and inhibits its conversion into amyloid fibrils
Chan, Pak Ho; Pardon, Els; Menzer, Linda ULg et al

in Biochemistry (2008), 47

single-domain fragment, cAb-HuL22, of a camelid heavy-chain antibody specific for the active site of human lysozyme has been generated, and its effects on the properties of the I56T and D67H amyloidogenic ... [more ▼]

single-domain fragment, cAb-HuL22, of a camelid heavy-chain antibody specific for the active site of human lysozyme has been generated, and its effects on the properties of the I56T and D67H amyloidogenic variants of human lysozyme, which are associated with a form of systemic amyloidosis, have been investigated by a wide range of biophysical techniques. Pulse-labeling hydrogen-deuterium exchange experiments monitored by mass spectrometry reveal that binding of the antibody fragment strongly inhibits the locally cooperative unfolding of the I56T and D67H variants and restores their global cooperativity to that characteristic of the wild-type protein. The antibody fragment was, however, not stable enough under the conditions used to explore its ability to perturb the aggregation behavior of the lysozyme amyloidogenic variants. We therefore engineered a more stable version of cAb-HuL22 by adding a disulfide bridge between the two beta-sheets in the hydrophobic core of the protein. The binding of this engineered antibody fragment to the amyloidogenic variants of lysozyme inhibited their aggregation into fibrils. These findings support the premise that the reduction in global cooperativity caused by the pathogenic mutations in the lysozyme gene is the determining feature underlying their amyloidogenicity. These observations indicate further that molecular targeting of enzyme active sites, and of protein binding sites in general, is an effective strategy for inhibiting or preventing the aberrant self-assembly process that is often a consequence of protein mutation and the origin of pathogenicity. Moreover, this work further demonstrates the unique properties of camelid single-domain antibody fragments as structural probes for studying the mechanism of aggregation and as potential inhibitors of fibril formation. [less ▲]

Detailed reference viewed: 111 (22 ULg)
Full Text
Peer Reviewed
See detailEngineering a Novel β-Lactamase by a Single Point Mutation
Jacob, F.; Joris, Bernard ULg; Dideberg, O. et al

in Protein Engineering (1990), 4(1), 79-86

beta-Lactamases are widespread and efficient bacterial enzymes which play a major role in bacterial resistance to penicillins and cephalosporins. In order to elucidate the role of the residues lying in a ... [more ▼]

beta-Lactamases are widespread and efficient bacterial enzymes which play a major role in bacterial resistance to penicillins and cephalosporins. In order to elucidate the role of the residues lying in a conserved loop of the enzymatic cavity of the active-site serine Streptomyces albus G beta-lactamase, modified proteins were produced by oligo-directed mutagenesis. Mutation of Asn116, which lies on one side of the active site cavity pointing to the substrate-binding site, into a serine residue resulted in spectacular modifications of the specificity profile of the enzyme. That replacement yielded an enzyme with a nearly unchanged activity towards good penicillin substrates. In sharp contrast its efficiency in hydrolysing cephalosporins was drastically reduced, the best substrates suffering the largest decrease in the second-order rate constant for serine acylation. In fact that single mutation generated a truly new enzyme behaving exclusively as a penicillinase, a situation which is never encountered to the same degree in any of the numerous naturally occurring variants of class A beta-lactamases. [less ▲]

Detailed reference viewed: 16 (3 ULg)
Full Text
See detailEngineering and characterisation of chimeric CXCR4 and CXCR7 chemokine receptors
Szpakowska, Martyna ULg; Fievez, Virginie; Counson, Manuel et al

Poster (2012, January)

Detailed reference viewed: 17 (0 ULg)
Full Text
See detailEngineering and manufacturing for biotechnology
Hofman, M.; Thonart, Philippe ULg

Book published by Kluwer academic publishers (2001)

Detailed reference viewed: 8 (2 ULg)
Full Text
Peer Reviewed
See detailEngineering and Overexpression of Periplasmic Forms of the Penicillin-Binding Protein 3 of Escherichia Coli
Fraipont, Claudine ULg; Adam, Maggy; Nguyen-Disteche, Martine et al

in Biochemical Journal (1994), 298(1), 189-195

Replacement of the 36 and 56 N-terminal amino acid residues of the 588-amino-acid-residue membrane-bound penicillin-binding protein 3 (PBP3) of Escherichia coli by the OmpA signal peptide allows export of ... [more ▼]

Replacement of the 36 and 56 N-terminal amino acid residues of the 588-amino-acid-residue membrane-bound penicillin-binding protein 3 (PBP3) of Escherichia coli by the OmpA signal peptide allows export of F37-V577 PBP3 and G57-V577 PBP3 respectively into the periplasm. The modified ftsI genes were placed under the control of the fused lpp promoter and lac promoter/operator; expression of the truncated PBP3s was optimized by varying the copy number of the recombinant plasmids and the amount of LacI repressor, and export was facilitated by increasing the SecB content of the producing strain. The periplasmic PBP3s (yield 8 mg/l of culture) were purified to 70% protein homogeneity. They require the presence of 0.25 M NaCl to remain soluble. Like the membrane-bound PBP3, they undergo processing by elimination of the C-terminal decapeptide I578-S588, they bind penicillin in a 1:1 molar ratio and they catalyse hydrolysis and aminolysis of acyclic thioesters that are analogues of penicillin. The membrane-anchor-free PBP3s have ragged N-termini. The G57-V577 PBP3, however, is less prone to proteolytic degradation than the F37-V577 PBP3. [less ▲]

Detailed reference viewed: 35 (1 ULg)
Full Text
Peer Reviewed
See detailEngineering geological conditions in the central area of Shanghai
Schroeder, Christian ULg; Dassargues, Alain ULg; Li, Xiang Lin

in Bulletin of Engineering Geology & the Environment (1992), 46

Detailed reference viewed: 19 (4 ULg)
Full Text
See detailEngineering geological mapping in Wallonia (Belgium) : present state and recent computerized approach
Delvoie, Simon ULg; Radu, Jean-Pol ULg; Ruthy, Ingrid ULg et al

Poster (2012, April)

An engineering geological map can be defined as a geological map with a generalized representation of all the components of a geological environment which are strongly required for spatial planning ... [more ▼]

An engineering geological map can be defined as a geological map with a generalized representation of all the components of a geological environment which are strongly required for spatial planning, design, construction and maintenance of civil engineering buildings. In Wallonia (Belgium) 24 engineering geological maps have been developed between the 70s and the 90s at 1/5,000 or 1/10,000 scale covering some areas of the most industrialized and urbanized cities (Liège, Charleroi and Mons). They were based on soil and subsoil data point (boring, drilling, penetration test, geophysical test, outcrop. . . ). Some displayed data present the depth (with isoheights) or the thickness (with isopachs) of the different subsoil layers up to about 50 m depth. Information about geomechanical properties of each subsoil layer,useful for engineers and urban planners, is also synthesized. However, these maps were built up only on paper and progressively needed to be updated with new soil and subsoil data. The Public Service of Wallonia and the University of Liège have recently initiated a study to evaluate the feasibility to develop engineering geological mapping with a computerized approach. Numerous and various data (about soil and subsoil) are stored into a georelational database (the geotechnical database – using Access, Microsoft®). All the data are geographically referenced. The database is linked to a GIS project (using ArcGIS, ESRI®). Both the database and GIS project consist of a powerful tool for spatial data management and analysis. This approach involves a methodology using interpolation methods to update the previous maps and to extent the coverage to new areas. The location (x, y, z) of each subsoil layer is then computed from data point. The geomechanical data of these layers are synthesized in an explanatory booklet joined to maps. [less ▲]

Detailed reference viewed: 22 (3 ULg)
Full Text
See detailEngineering Geology Conditions of the Central Area of Shanghai : Preparation of the data for subsidence modelling
Dassargues, Alain ULg; Schroeder, Christian ULg; Monjoie, Albéric ULg

in Sixth International Congress of the International Association of Engineering Geology, Amsterdam (1990, August)

Detailed reference viewed: 69 (4 ULg)
Full Text
Peer Reviewed
See detailEngineering Multiferroism in CaMnO3
Bhattacharjee, Satadeep; Bousquet, Eric ULg; Ghosez, Philippe ULg

in Physical Review Letters (2009), 102

Structural instabilities of CaMnO3 are investigated from first principles. We point out that, on top of a strong antiferrodistortive instability responsible for its orthorhombic ground state, the cubic ... [more ▼]

Structural instabilities of CaMnO3 are investigated from first principles. We point out that, on top of a strong antiferrodistortive instability responsible for its orthorhombic ground state, the cubic perovskite structure of CaMnO3 also exhibits a weak ferroelectric instability. Although ferroelectricity is suppressed by antiferrodistortive motions, we show that it can be favored using strain or chemical engineering in order to make CaMnO3 multiferroic. We finally highlight that the ferroelectric instability of CaMnO3 is Mn-dominated. This illustrates that, contrary to common belief, ferroelectricity and magnetism are not necessarily exclusive but can be driven by the same cation. [less ▲]

Detailed reference viewed: 49 (1 ULg)
Full Text
See detailEngineering of poly(2-oxazoline)s for a potential use in biomedical applications
Legros, Camille ULg

Doctoral thesis (2014)

This PhD work is based on the design of poly(2-oxazoline) (POx) hydrogels and nanogels, by chemical or physical cross-linking, aimed to be used for biomedical applications. Nanogels were first prepared in ... [more ▼]

This PhD work is based on the design of poly(2-oxazoline) (POx) hydrogels and nanogels, by chemical or physical cross-linking, aimed to be used for biomedical applications. Nanogels were first prepared in dilute media and in inverse emulsion based on a statistical copolymer made of 2-ethyl-2-oxazoline and ethylene imine units. These stimuli-responsive nanogels were swelling in acidic media and were cleaved in reductive environment. They proved to be non-cytotoxic and act as protein repellent. Second, a reactive platform based on a statistical POx polymer bearing aldehyde functionalities was engineered, enabling the synthesis of graft and cross-linked POx. Last, a block copolymer made of 2-methyl- and 2-isopropyl-2- oxazoline units, proved to self-assemble into micelles when heated above its LCST, for a short period of time (< 1h30). When annealed for a longer time (> 1h30), crystallization-driven self-assembly led to the formation of different morphologies (fiber rods and cross-linked micelles). [less ▲]

Detailed reference viewed: 10 (3 ULg)
Full Text
Peer Reviewed
See detailEngineering resistance to geminiviruses--review and perspectives.
Vanderschuren, Hervé ULg; Stupak, Martin; Futterer, Johannes et al

in Plant biotechnology journal (2007), 5(2), 207-20

Following the conceptual development of virus resistance strategies ranging from coat protein-mediated interference of virus propagation to RNA-mediated virus gene silencing, much progress has been ... [more ▼]

Following the conceptual development of virus resistance strategies ranging from coat protein-mediated interference of virus propagation to RNA-mediated virus gene silencing, much progress has been achieved to protect plants against RNA and DNA virus infections. Geminiviruses are a major threat to world agriculture, and breeding resistant crops against these DNA viruses is one of the major challenges faced by plant virologists and biotechnologists. In this article, we review the most recent transgene-based approaches that have been developed to achieve durable geminivirus resistance. Although most of the strategies have been tested in model plant systems, they are ready to be adopted for the protection of crop plants. Furthermore, a better understanding of geminivirus gene and protein functions, as well as the native immune system which protects plants against viruses, will allow us to develop novel tools to expand our current capacity to stabilize crop production in geminivirus epidemic zones. [less ▲]

Detailed reference viewed: 6 (0 ULg)
See detailEngineering RNA-mediated resistance to geminiviruses in cassava
Vanderschuren, Hervé ULg

Doctoral thesis (2007)

Cassava mosaic disease (CMD) is the most important disease affecting cassava in Africa. The disease is caused by several whitefly-transmitted geminivirus species. The increasing impact of geminivirus ... [more ▼]

Cassava mosaic disease (CMD) is the most important disease affecting cassava in Africa. The disease is caused by several whitefly-transmitted geminivirus species. The increasing impact of geminivirus-caused diseases on cassava production due to the recent pandemics has urged the scientific community to provide stable virus resistance in cassava. Advances in engineering virus resistance via RNA-based strategies have opened promising perspectives for the production of transgenic geminivirus resistant plants. In this thesis, three RNA-based strategies are developed to improve the resistance to African cassava mosaic virus (ACMV) in transgenic cassava. The first strategy was based on expression of antisense viral sequences. Three different viral coding sequences were targeted and several transgenic cassava lines expressing antisense viral sequences were ACMV resistant. The second strategy was to express intron hairpin double-stranded RNAs (dsRNAs) homologous to ACMV bidirectional Promoter. Transgenic cassava lines expressing small dsRNAs homologous to the ACMV promoter were not completely immune to ACMV infection but showed an enhanced recovery phenotype as cornpared to the infected wild-type cassava plants. The third strategy relied on the expression of intron hairpin dsRNAs homologousto viral coding sequences. Transgenic cassava lines expressing high levels of small RNAs homologous to the viral coding sequences were immune under ACMV infection tests in which virus load had been sufficient to break resistance elaborated with the first two strategies. This work demonstrated that ACMV resistance could be achieved in cassava via an RNA-based approach and that the strategy used (i.e. antisense RNA, hairpin dsRNA against non-coding viral sequence, hairpin dsRNA against viral coding sequences) had an impact on the resistance level. [less ▲]

Detailed reference viewed: 22 (1 ULg)
Peer Reviewed
See detailEngineering the stability of a cold-active alpha-amylase
D'Amico, Salvino; Gerday, Charles ULg; Feller, Georges ULg

Poster (1999)

Detailed reference viewed: 8 (0 ULg)