References of "2003"
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See detailNew disruption cassettes for rapid gene disruption and marker rescue in the yeast Yarrowia lipolytica
Fickers, Patrick ULiege; Le Dall, M. T.; Gaillardin, C. et al

in Journal of Microbiological Methods (2003), 55(3), 727-737

Yarrowia lipolytica is one of the most extensively studied nonconventional yeasts. Unfortunately, few methods for gene disruption have been reported for this yeast, and all of them are time-consuming and ... [more ▼]

Yarrowia lipolytica is one of the most extensively studied nonconventional yeasts. Unfortunately, few methods for gene disruption have been reported for this yeast, and all of them are time-consuming and laborious. The functional analysis of unknown genes requires powerful disruption methods. Here, we describe such a new method for rapid gene disruption in Y lipolytica. This knockout system combines SEP method and the Cre-lox recombination system, facilitating efficient marker rescue. Versatility was increased by using both auxotrophic markers like ylURA3 and ylLEU2, as well as the antibiotic resistance marker hph. The hph marker, which confers resistance to hygromycin-B, allows gene disruption in a strain lacking any conventional auxothrophic marker. The disruption cassette was shown to integrate at the correct locus at an average frequency of 45%. Upon expression of Cre recombinase, the marker was excised at a frequency of 98%, by recombination between the two lox sites. This new method for gene disruption is an ideal tool for the functional analysis of gene families, or for creating large-scale mutant collections in general. (C) 2003 Elsevier B.V. All rights reserved. [less ▲]

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See detailOverproduction of lipase by Yarrowia lipolytica mutants
Fickers, Patrick ULiege; Nicaud, J. M.; Destain, Jacqueline ULiege et al

in Applied Microbiology & Biotechnology (2003), 63(2), 136-142

Non-genetically modified mutants with increased capacities of extracellular lipase production were obtained from Yarrowia lipolytica strain CBS6303 by chemical mutagenesis. Of the 400 mutants isolated ... [more ▼]

Non-genetically modified mutants with increased capacities of extracellular lipase production were obtained from Yarrowia lipolytica strain CBS6303 by chemical mutagenesis. Of the 400 mutants isolated, LgX64.81 had the highest potential for the development of an industrial lipase production process. This mutant exhibits lipase production uncoupled from catabolite repression by glucose, and a 10-fold increased productivity upon addition of oleic acid. Using a LIP2-LacZ reporter gene, we demonstrate that the mutant phenotype originates from a trans-acting mutation. The glucose uptake capacity of LgX64.81 is reduced 2.5-fold compared to the wild-type-strain, and it exhibits high lipase production on glucose medium. A trans-acting mutation in a gene involved in glucose transport could thus explain this mutant phenotype. [less ▲]

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See detailPsychrophilic enzymes: Hot topics in cold adaptation
Feller, Georges ULiege; Gerday, Charles ULiege

in Nature Reviews Microbiology (2003), 1(3), 200-208

More than three-quarters of the Earth's surface is occupied by cold ecosystems, including the ocean depths, and polar and alpine regions. These permanently cold environments have been successfully ... [more ▼]

More than three-quarters of the Earth's surface is occupied by cold ecosystems, including the ocean depths, and polar and alpine regions. These permanently cold environments have been successfully colonized by a class of extremophilic microorganisms that are known as psychrophiles (which literally means cold-loving). The ability to thrive at temperatures that are close to, or below, the freezing point of water requires a vast array of adaptations to maintain the metabolic rates and sustained growth compatible with life in these severe environmental conditions. [less ▲]

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See detailQuantitative analysis of strychnine and brucine in Strychnos nux-vomica using H-1-NMR
Frederich, Michel ULiege; Choi, Y. H.; Verpoorte, R.

in Planta Medica (2003), 69(12), 1169-1171

A quantitative analysis using H-1-NMR (Q-NMR) has been developed for the determination of strychnine and brucine in Strychnos nux-vomica seeds and stems. The advantages of the method are that no reference ... [more ▼]

A quantitative analysis using H-1-NMR (Q-NMR) has been developed for the determination of strychnine and brucine in Strychnos nux-vomica seeds and stems. The advantages of the method are that no reference alkaloids are needed for calibration curves, the quantification could be directly realized on a crude extract, strychnine and brucine could easily be distinguished, an overall profile of the preparation (including non alkaloid compounds) could be directly obtained, and a very significant time-gain could be achieved, in comparison to conventional HPLC methods, for instance. [less ▲]

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See detailRise and survival of bovine herpesvirus 1 recombinants after primary infection and reactivation from latency
Schynts, F.; Meurens, F.; Detry, Bruno et al

in Journal of Virology (2003), 77(23), 12535-12542

Recombination is thought to be an important source of genetic variation in herpesviruses. Several studies, performed in vitro or in vivo, detected recombinant viruses after the coinoculation of two ... [more ▼]

Recombination is thought to be an important source of genetic variation in herpesviruses. Several studies, performed in vitro or in vivo, detected recombinant viruses after the coinoculation of two distinguishable strains of the same herpesvirus species. However, none of these studies investigated the evolution of the relative proportions of parental versus recombinant progeny populations after coinoculation of the natural host, both during the excretion and the reexcretion period. In the present study, we address this by studying the infection of cattle with bovine herpesvirus 1 (BoHV-1). The recombination of two BoHV-1 mutants lacking either glycoprotein C (gC(-)/gE(+)) or E (gC(+)/gE(-)) was investigated after inoculation of cattle by the natural route of infection. The results demonstrated that (i) recombination is a frequent event in vivo since recombinants (gC(+)/gE(+) and gC(-)/gE(-)) were detected in all coinoculated calves, (ii) relative proportions of progeny populations evolved during the excretion period toward a situation where two populations (gC(+)/gE(+) and gC(-)/gE(+)) predominated without fully outcompeting the presence of the two other detected populations (gC(+)/gE(-) and gC(-)/gE(-)), and (iii) after reactivation from latency, no gC(+)/gE(-) and gC(-)/gE(-) progeny viruses were detected, although gC(+)/gE(-) mutants, when inoculated alone, were detected after reactivation treatment. In view of these data, the importance of gE in the biology of BoHV-1 infection and the role of recombination in herpesvirus evolution are discussed. [less ▲]

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See detailThe aromatase knockout (ArKO) mouse provides new evidence that estrogens are required for the development of the female brain
Bakker, Julie ULiege; Honda, S.; Harada, N. et al

in Annals of the New York Academy of Sciences (2003), 1007

The classic view of sexual differentiation is that the male brain develops under the influence of testicular secretions, whereas the female brain develops in the absence of any hormonal stimulation ... [more ▼]

The classic view of sexual differentiation is that the male brain develops under the influence of testicular secretions, whereas the female brain develops in the absence of any hormonal stimulation. However, several studies have suggested a possible role of estradiol in female neural development, although they did not provide unequivocal evidence that estradiol is indispensable for the development of the female brain and behavior. As a result, the hypothesis subsequently languished because of the lack of a suitable animal model to test estrogen's possible contribution to female differentiation. The recent introduction of the aromatase knockout (ArKO) mouse, which is deficient in aromatase activity because of a targeted mutation in the CYP19 gene and therefore cannot aromatize androgen to estrogen, has provided a new opportunity to reopen the debate of whether estradiol contributes to the development of the female brain. Female ArKO mice showed reduced levels of lordosis behavior after adult treatment with estradiol and progesterone, suggesting that estradiol is required for the development of the neural mechanisms controlling this behavior in female mice. The neural systems affected may include the olfactory systems in that ArKO females also showed impairments in olfactory investigation of odors from conspecifics. Thus, the classic view of sexual differentiation, that is, the female brain develops in the absence of any hormonal secretion, needs to be re-examined. [less ▲]

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See detailThe influence of an acid-base-equilibrium on the adsorption behaviour of a weak polyampholyte
Mahltig, Boris; Jérôme, Robert ULiege; Stamm, Manfred

in Journal of Polymer Research (2003), 10(4), 219-223

A weak diblock polyampholyte PMAA-b-PDMAEMA, poly(methacrylic acid)-block-poly((dimethylamino)ethyl methacrylate), was investigated as a model system for the influence of an acid-base-equilibrium of a ... [more ▼]

A weak diblock polyampholyte PMAA-b-PDMAEMA, poly(methacrylic acid)-block-poly((dimethylamino)ethyl methacrylate), was investigated as a model system for the influence of an acid-base-equilibrium of a phthalic acid buffer system on the polyelectrolyte adsorption behaviour. The adsorption of polyampholyte from aqueous solution onto silicon surfaces is known to be strongly influenced by the parameters of the polymer solution and the properties of the polyampholyte itself like block ratio or molecular weight. In the case of the investigated polyampholytes, the main parameter with the most significant influence on the adsorption is the pH. The big influence of pH on adsorption results from the charges of the polymer chains and the substrate, which are determined by the pH. Therefore, it should be useful to investigate the influence of a buffer system on the polyampholyte adsorption. On the one hand the buffer system enables to determine the pH of the aqueous polyampholyte solution more precisely. On the other hand the concentrations of different phthalic species like the phthalic acid, the hydrogen phthalate and the phthalate are strongly influenced by pH. These different species were observed to have a strong influence on the adsorption behaviour of the polyampholyte, so the adsorption as function of pH was observed to be also determined by the acid-base-equilibrium of the buffer system. The adsorbed amount of polyampholyte dried after the adsorption process was determined using ellipsometry, while the surface topography of these adsorbed layers were characterized by atomic force microscopy (AFM). [less ▲]

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See detailEOF calculations and data filling from incomplete oceanographic datasets
Beckers, Jean-Marie ULiege; Rixen, M.

in Journal of Atmospheric and Oceanic Technology (2003), 20(12), 1839-1856

The paper presents a new self-consistent method to infer missing data from oceanographic data series and to extract the relevant empirical orthogonal functions. As a by-product, the new method allows for ... [more ▼]

The paper presents a new self-consistent method to infer missing data from oceanographic data series and to extract the relevant empirical orthogonal functions. As a by-product, the new method allows for the detection of the number of statistically significant EOFs by a cross-validation procedure for a complete or incomplete dataset, as well as the noise level and interpolation error. Since the proposed filling and analysis method does not need a priori information about the error covariance structure, the method is self-consistent and parameter free. [less ▲]

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See detailPharmacological evaluation of BM-573, a dual thromboxane A2 receptor antagonist and thromboxane synthase inhibitor, as potential anti-metastatic agent
De Leval, X.; Dassesse, T.; Benoît, V. et al

Poster (2003, December)

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See detailBM-613, a new thromboxane A2 antagonist, is characterized by a preferential activity on platelet thromboxane A2 receptors
Hanson, Julien ULiege; Rolin, S.; De Leval, X. et al

Poster (2003, December)

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See detailSoft tissue attachment formation at titanium abutments in humans: a new model
Rompen, Eric ULiege; Domken, Olivier ULiege; Lamy, Marc ULiege et al

in Journal of Dental Research (2003, December), 82(Sp. Iss. C), 510

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See detailPreventive assessment and enhancement of power system voltage stability: an integrated approach of thermal and voltage security
Capitanescu, Florin ULiege

Doctoral thesis (2003)

This thesis is devoted to the preventive assessment and enhancement of voltage stability and security in electric power systems. However, in the course of deriving all the proposed methods we have paid ... [more ▼]

This thesis is devoted to the preventive assessment and enhancement of voltage stability and security in electric power systems. However, in the course of deriving all the proposed methods we have paid attention to keeping them compatible with the (more traditional) handling of thermal overloads, thereby providing a unified treatment of voltage and thermal security. The approaches presented in this work apply to both deregulated environments and classical, vertically integrated ones. The heart of most methods developed in this thesis is : (i) the derivation of sensitivities indicating the relative efficiency of the various bus injections to restore voltage stability or increase an insufficient voltage security margin, and (ii) the use of these sensitivities in linearized security constraints that can be incorporated to various optimization problems. Using this formulation, we deal with three different problems of interest in preventive security analysis: 1) Congestion management. We propose two optimization-based approaches to manage congestions due to voltage instability and/or thermal overload. The control variables are either power injections (generation rescheduling and load curtailment) or power transactions; 2) Computation of Available Transfer Capabilities (ATCs). We determine the simultaneous ATCs of multiple transactions by means of a single optimization-based computation; 3) evaluation of security margins interval. To face the uncertainty affecting power transfers, we present an optimization-based computation of the minimal and maximal margins under the assumption that individual injections vary within specified bounds. Besides this main theme, the thesis offers additional reflections on the: 1) Filtering of contingencies. We propose a simple and reliable technique to filter out harmless contingencies when computing voltage security margins of a large set of contingencies; 2) Evaluation of reactive reserves with respect to a contingency, an important topic for voltage security reasons as well as within the context of a deregulated market where providing reactive reserves is an ancillary service which should be properly paid. Most of the methods proposed in this thesis were successfully tested on realistic power system models. From a practical viewpoint all the above computations have been coupled to the fast time-domain quasi steady-state simulation used in the ASTRE software developed at the University of Liège. [less ▲]

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See detailMale hypogonadism caused by isolated LH deficiency : From pathology to gene, from gene to physiology
Valdes Socin, Hernan Gonzalo ULiege; Salvi, R.; Pralong, F. et al

in Meeting of the Belgian Endocrine Society : December 2003 (2003, December)

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See detailSegmentation by adaptive prediction and region merging
Van Droogenbroeck, Marc ULiege; Talbot, Hugues

in Digital Image Computing Techniques and Applications, Volume II (2003, December)

This paper presents a segmentation technique based on prediction and adaptive region merging. While many techniques for segmentation exist, few of them are suited for the segmentation of natural images ... [more ▼]

This paper presents a segmentation technique based on prediction and adaptive region merging. While many techniques for segmentation exist, few of them are suited for the segmentation of natural images containing regular textures defined on non-rectangular segments. In this paper, we propose a description of regions based on a deconvolution algorithm whose purpose is to remove the influence of the shape on region contents. The decoupling of shape and texture information is achieved either by adapting waveforms to the segment shape, which is a time-consuming task that needs to be repeated for each segment shape, or by the extrapolation of a signal to fit a rectangular window, which is the chosen path. The deconvolution algorithm is the key of a new segmentation technique that uses extrapolation as a prediction of neighbouring regions. When the prediction of a region fits the actual content of a connected region reasonably well, both regions are merged. The segmentation process starts with an over-segmented image. It progressively merges neighbouring regions whose extrapolations fit according to an energy criterion. After each merge, the algorithm updates the values of the merging criterion for regions connected to the merged region pair. It stops when no further gain is achieved in merging regions or when mean values of adjacent regions are too different. Simulation results indicate that, although our technique is tailored for natural images containing periodic signals and flat regions, it is in fact usable for a large set of natural images. [less ▲]

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See detailEffect of hemodiafiltration on pulmonary hemodynamics in endotoxic shock
Lambermont, Bernard ULiege; Kolh, Philippe ULiege; Ghuysen, Alexandre ULiege et al

in Artificial Organs (2003), 27(12), 1128-1133

Hemofiltration can improve pulmonary hemodynamics during septic shock. The main objective of the study was to determine whether hemodiafiltration (HDF) would also have beneficial effects on pulmonary ... [more ▼]

Hemofiltration can improve pulmonary hemodynamics during septic shock. The main objective of the study was to determine whether hemodiafiltration (HDF) would also have beneficial effects on pulmonary hemodynamics during septic shock. In the Endo group, six anesthetized pigs received a 0.5 mg/kg endotoxin infusion over 30 min. In the HDF group (n = 6), HDF was started 30 min after the end of the endotoxin infusion, while in the Control group (n = 4) they received HDF but no endotoxin infusion. Pulmonary hemodynamics were analyzed in detail with a four-element windkessel model. Although in the Control group, HDF did not alter pulmonary hemodynamic parameters, in the HDF group, it was responsible for an amplification of the deleterious pulmonary vascular response to endotoxin insult. Our results show that HDF must be used cautiously in septic shock since it can precipitate right heart failure by increasing pulmonary vascular resistance. [less ▲]

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See detailSystemic and pulmonary hemodynamics assessed with a lumped-parameter heart-arterial interaction model
Segers, P.; Stergiopulos, N.; Westerhof, N. et al

in Journal of Engineering Mathematics (2003), 47(3-4), 185-199

Arterial pressure and flow result from the interaction between the ( actively) ejecting ventricle and the ( passive) arterial circulation. The main objective was to construct a model, accounting for this ... [more ▼]

Arterial pressure and flow result from the interaction between the ( actively) ejecting ventricle and the ( passive) arterial circulation. The main objective was to construct a model, accounting for this interaction, that is simple enough so that (i) model parameters can be derived from data measured in experimental and/or clinical conditions, and (ii) the model can be applied to support the analysis and interpretation of these data. It is demonstrated how an established conceptual model of ventricular function ( the time-varying elastance) can be coupled to a four-element windkessel model of the arterial system to yield an elegant model of heart-arterial interaction. The coupling leads to a set of three ordinary differential equations. The model allows the study of the effect of changes in cardiac and/or arterial properties on arterial pressure and flow. As an illustration, cardiac and arterial model parameters are derived from measured experimental data in the systemic circulation of a pig and in the pulmonary circulation of a dog. It is evaluated how well measured cardiac and arterial function actually adhere to their assumed theoretical models (time-varying elastance and four-element windkessel model). It is further assessed how well the simple model of heart-arterial interaction describes systemic and pulmonary hemodynamics by comparing simulated and measured experimental data. The limitations and pitfalls of the model, as well as possible applications in the clinical field, are discussed. [less ▲]

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See detailUn élément Epontilles pour LBR5-Report R&D5
Rigo, Philippe ULiege

Report (2003)

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