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See detailTranscription factor Pit-1 expression is modulated upon seasonal acclimatization of eurythermal ectotherms: Identification of two Pit-1 genes in the carp
Kausel, Gudrun; Vera, María Inés; San Martin, Rody et al

in Journal of Cellular Biochemistry (1999), 75(4), 598-609

A second Pit-1 gene in carp (Cyprinus carpio), including the complete structural gene and 1.1 kb of promoter region, was identified and completely sequenced. The exon-intron structure was determined, and ... [more ▼]

A second Pit-1 gene in carp (Cyprinus carpio), including the complete structural gene and 1.1 kb of promoter region, was identified and completely sequenced. The exon-intron structure was determined, and reverse transcription-polymerase chain reaction (RT-PCR) experiments suggest that only one Pit-1 splice variant is present in carp pituitary. The effect of seasonal acclimatization on the extent of Pit-1 gene expression was studied in summer- and winter-acclimatized carp. Quantitative RT-PCR analysis revealed a clear increase of Pit-1 mRNA in the pituitaries from summer-acclimatized carp compared with the winter-adapted fish. In situ hybridization of pituitary gland sections with riboprobes representing the complete 5-transactivating region of carp Pit-1 depicted a significantly higher Pit-1 mRNA level in the rostral pars distalis of the summer-acclimatized fish where prolactin is expressed in a manner that resembles the seasonal increase observed in the proximal pars distalis and the pars intermedia. The cell- and temporal-specific transcription of Pit-1 supports its role in the molecular mechanisms that underly the acclimatization process undergone by eurythermal fish as a result of the physical effects of seasonal changes on their habitat. J. Cell. Biochem. 75:598-609, 1999. © 1999 Wiley-Liss, Inc. [less ▲]

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See detailLe collage structural : Préparation de surface et durabilité (Corrosion et durabilité des assemblages collés) - Journée d'étude organisée par la SRBII (société Royale Belge des ingénieurs et des Industriels) et le CRIF
Lecomte-Beckers, Jacqueline ULg

Conference (1999, November 03)

L'exposé s'attachera à définir les principaux problèmes liés au phénomène de corrosion dans les métaux. On abordera les différents types de corrosion (corrosion aqueuse, corrosion atmosphérique, corrosion ... [more ▼]

L'exposé s'attachera à définir les principaux problèmes liés au phénomène de corrosion dans les métaux. On abordera les différents types de corrosion (corrosion aqueuse, corrosion atmosphérique, corrosion sèche et corrosion bactérienne). L'accent sera mis sur les phénomènes électrochimiques de base liés à la corrosion aqueuse. On abordera les réactions d'électrodes et de piles du point de vue thermodynamique (diagramme de Pourbaix) et cinétique. On rappellera les différentes formes de corrosion (généralisée, par piqûres, galvanique, caverneuse, intergranulaire, sélective) ainsi que les problèmes couplés de corrosion érosion et de corrosion sous tension. Certains problèmes spécifiques liés aux assemblages collés seront abordés. L'exposé reprendra les différentes possibilités de lutte contre la corrosion. [less ▲]

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See detailEvolution on trees: a brief review about the extinctions of species, and the case of genocide in a Darwinistic punctuated equilibrium evolution model
Ausloos, Marcel ULg; Kramer, M.; Vandewalle, Nicolas ULg

in Physica A: Statistical Mechanics and its Applications (1999), 273(1-2), 33-45

Numerical and theoretical investigations of species evolution in presence of extinction rules are recalled in the framework of punctuated equilibrium evolution models. Previous results, on the Bak-Sneppen ... [more ▼]

Numerical and theoretical investigations of species evolution in presence of extinction rules are recalled in the framework of punctuated equilibrium evolution models. Previous results, on the Bak-Sneppen model are mentioned together with extensions taking into account a variable number of species. Conditions for limited growth due to species interactions, external fields, or intrinsic population density conditions have already been considered. An original genocide model is presented as a step towards describing effects due to the extinction of species. Critical exponents for (i) the avalanche distribution. (ii) the teady-state approach, and (iii) the tree size are given. A mean-field approximation is shown to be quite accurate for describing the critical state. The screening of species from the evolution process is not numerically studied. [less ▲]

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See detailInflammatory Effect of Intratracheal Instillation of Ultrafine Particles in the Rabbit: Role of C-Fiber and Mast Cells
Nemmar, A.; Delaunois, Annie ULg; Nemery, B. et al

in Toxicology and Applied Pharmacology (1999), 160(3), 250-61

The effects of ultrafine polystyrene carboxylate-modified (fluorospheres) on inflammatory processes are being investigated in rabbit lungs. One milliliter of sterile NaCl (0.9%) containing 4 mg of ... [more ▼]

The effects of ultrafine polystyrene carboxylate-modified (fluorospheres) on inflammatory processes are being investigated in rabbit lungs. One milliliter of sterile NaCl (0.9%) containing 4 mg of ultrafine particles (UFP) was intratracheally instilled into anesthetized rabbits. The control animals were only instilled with sterile NaCl (0.9%). Twenty hours after being instilled, the rabbits were killed and their lungs were excised and then tracheally perfused with phosphate-buffered physiological solution (PBS). The lung effluents, collected from small holes made in the pleura, were analyzed for substance P (SP) and histamine content by radioimmunoassay (RIA) methods, after administration of drugs. In addition, in other groups of rabbits, the lung wet/dry (W/D) weight ratio was monitored, as were the cellular and protein contents in bronchoalveolar lavage (BAL). Electron microscopy examination was also performed. In tracheally superfused experiments, UFP induced a significant enhancement of both SP and histamine releases after administration of capsaicin (10(-4) M), to stimulate C-fiber, and carbachol (10(-4) M), a cholinergic agonist. A significant increase in histamine release was also recorded in the UFP-instilled group following the administration of both SP (10(-6) M) plus thiorphan (10(-5) M) and compound 48/80 (C48/80) (10(-3) M) to stimulate mast cells. In addition, the BAL fluid analysis of UFP groups showed an influx of neutrophils and an increase in total protein concentration. An increase in the lung WW/DW ratio was also recorded. Both epithelial and endothelial injuries were observed in the lungs of UFP-instilled rabbits. The pretreatment of rabbits in vivo with a mixture of either SR 140333 and SR 48368, a tachykinin NK(1) and NK(2) receptor antagonist, or a mixture of terfenadine and cimetidine, a histamine H(1) and H(2) receptor antagonist, prevented UFP- induced neutrophil influx and increased total proteins and lung WW/DW ratio. Therefore, it can be concluded that chemicaly inert, electrically charged UFP induce a pulmonary inflammatory process during which the release of SP and histamine from C-fibers and mast cells was enhanced after various stimuli. These latter mediators can also modulate the inflammatory process. [less ▲]

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See detailL'approche expérimentale est-elle adaptée à l'évaluation des actions d'éducation pour la santé ?
Liesse, Anne; Vandoorne, Chantal ULg

in Education Santé (1999), (143), 5-8

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See detailLe cas clinique du mois. Le cerebral salt wasting syndrome: a propos d'un cas
Llabres, V.; Canivet, Jean-Luc ULg; Hennuy, V. et al

in Revue Médicale de Liège (1999), 54(11), 850-853

A 75 year old woman was found to have a posterior cerebellar lesion which after surgical removal was shown to be a meningioma. Her postoperative course was complicated by a MRSA meningitis and on day 23 ... [more ▼]

A 75 year old woman was found to have a posterior cerebellar lesion which after surgical removal was shown to be a meningioma. Her postoperative course was complicated by a MRSA meningitis and on day 23 after resection, a polyuria up to 11.7 1/24 h became apparent. The diagnosis of cerebral wasting syndrome (CSWS) was made based on biological and clinical features such as an excessive natriuresis (143 mmol/l) resulting in hyponatremia (130 mmol/l) and an osmolarity higher in urine than in blood. A low central venous pressure and a low wedge pressure confirming a volumic depletion indicated the diagnosis of CSWS. This syndrome has marked similarities with the Inappropriate Secretion of Antidiuretic Hormone Syndrome (SIADH) in terms of biological finding with regards to clinical context and presentation. Without an adequate assessment, a patient with CSWS may be misdiagnosed as SIADH. However recognition is important, as water restriction which is part of SIADH treatment, is detrimental to patients with CSWS and can possibly be lethal. [less ▲]

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See detailQuelle(s) correction(s) géométrique(s) pour la très haute résolution ?
Billen, Roland ULg; Cornélis, Bernard; Donnay, Jean-Paul ULg et al

Poster (1999, November)

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See detailConfrontation anatomo-clinique. A propos d'un cas de carcinome renal a cellules claires
Daloze, A.; Delbecque, Katty ULg; Delvenne, Philippe ULg et al

in Revue Médicale de Liège (1999), 54(11), 859-63

The authors report the case of a patient with a history of hypertension and multiple intracerebral hemorrhages who was found at post mortem examination to have a renal cell carcinoma. The relationship ... [more ▼]

The authors report the case of a patient with a history of hypertension and multiple intracerebral hemorrhages who was found at post mortem examination to have a renal cell carcinoma. The relationship between renal carcinoma and hypertensive intracerebral hemorrhages is discussed. [less ▲]

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See detailEvolution régressive récente de la végétation des tourbières hautes à sphaignes en Haute Ardenne (Hautes-Fagnes, Belgique)
Hindryckx, Marie-Noëlle ULg

Doctoral thesis (1999)

In temperate Europe, intact raised bogs from Northern Germany to the French Massif Central are part of rare postglacial ecosystems that one can consider as natural or very close to the natural state ... [more ▼]

In temperate Europe, intact raised bogs from Northern Germany to the French Massif Central are part of rare postglacial ecosystems that one can consider as natural or very close to the natural state. Unfortunately, many of them have been degraded or highly disturbed by intense human activities. Some of them, however, kept a subintact central part. This is the case for the three big raised bogs situated in the Hautes-Fagnes plateau in Belgium: the fagne Wallonne, the fagne de Clefaye and the Misten raised bogs. Their vegetation belongs to the Vaccinio oxycocci-Sphagnetea magellanici Br.-Bl. & Tx. 43 and Eriophoro vaginati-Sphagnetalia papillosi Tx. 70. But the legal conservation measures are not sufficient to guarantee their protection : in the course of the last 30 years, 10 to 25% of the area covered with intact raised bogs of the Hautes-Fagnes plateau have been degraded, mainly invaded by Molinia caerulea. Although it is important to bring forward such alarming observations, it is more essential to understand exactly the origin of the factors causing the degradation, if suitable measures to thwart the factors that condition them, and try to attenuate if not suppress their harmful effects, and thereby restore the conditions that will enable the natural vegetation from these environments to recover the lost areas. Here are the main objectives of this work: • To highlight the current and recent ecological and phytodynamic consequences of the degradation of the raised bogs; • To identify and date the causes of the degradation that struck the intact parts of the raised bogs present on the Hautes-Fagnes plateau; • To examine the practical management measures in the short-, medium-, and long-term taken in Belgium and abroad in order to restore the natural evolution of the peatlands. Studies of the vegetation The vegetation maps, on a scale of 1/250, indicate that, despite some differences, the degradation phenomenon seems to begin in the same way in the three bogs. We can notice: • an invasion by Molinia caerulea of the intact peat areas (in sometimes very high tussocks) but also its presence, in a more diffuse form, within the -narrowzones of transition and even among typical bog species; • a soil draining, resulting in the proliferation of Ericaceae, especially around relatively intact zones; • the existence of Deschampsia flexuosa, which seems to be linked to rather steep slopes at the edge of zones exclusively colonised by Molinia caerulea,; • the poor representation, both in terms of quality as quantity, of bryophytes; fewer than 10 species of peatmosses occur in these peatlands, where they are often little or ill-developed; • the occupation of peat bogs by relatively exclusive species (Empetrum nigrum, Molinia caerulea and other very thick Ericaceae bushes) which prevent other peat forming communities from developing. The analysis of the vegetation releves taken along three transects shows that the Misten bog appears as the most intact one (or the best preserved one) based on the cover, distribution and vitality of peatmosses, although as indicated by the vegetation map, Molinia caerulea surrounds this raised bog. The fagne de Clefaye peat bog seems much drier and the percentage of peatmosses cover is lower compared to the Misten bog. Some Empetrum nigrum clumps no longer contain any mosses. On the other hand, this bog holds more Sphagnum species than either of the other two bogs investigated. The raised bog of the fagne Wallonne is the most degraded one (at least the north-west part of it). The complexity of the problem composed already the focus of several studies as part of a graduate work. In order to have some idea of the evolution of the vegetation, all the releves which have been carried out along the transects of the three bogs have been the subject of an observation follow-up. Even if six or seven years between the vegetation releves is too short a time to show some significant evolution in a peat bog, the results nonetheless enable to bring to the fore some trends in the evolution of the vegetation present in the main bogs of the haut-plateau, Along the itemised transect, the vegetation of the peat bog seems to be stable and optimal for a peat forming activity typical of an ombrotrophic raised bog, to develop. The northern part of the fagne Wallonne bog shows much more worrying signs of evolution (heaths developing quickly) or signs of degradation of its vegetation (reduction of the number of peatmosses, increasing density of Molinia caerulea, and invasion by Betula alba subsp. glutinosa). The vegetation of the fagne de Cléfaye bog clearly evolves towards a drier phase (high intensification of heaths development) without leading to the rarefaction of peatmosses. We wanted to put these evolutional studies in a broader context and take advantage of previous studies carried out on the haut-plateau in similar conditions. Despite the interpretation difficulties that were met, the different studies allow to assert that there has been a quick change in the vegetation of the raised bogs in the last forty years. Are we in the presence of a Natural evolution or a degradation process? The ground cover in the northern part of the fagne Wallonne bog shows obvious signs of degradation. The southern part of it as well as the fagne de Cléfaye bog show instead an evolution of the vegetation towards a stage heavily composed of heaths, with, however, a strong reduction of peatmosses. The Misten bog seems to experience the slowest evolution: is this a former evolution stage of the vegetation or is the balance achieved? Hydrological studies In natural conditions, the fluctuations of the water table of an ombrotrophic bog on a one-year scale remain modest: about 10 centimetres from one season to the other. It is thus interesting to check if the variations of the water table level are of the same nature in different spots of the three studied bogs or if the alteration phenomena, that are visible at the vegetation level and are present on the three bogs also appear in the behaviour of water tables at the surface of these bogs. Based on the follow-up of the 148 dip wells scattered on the three peat bogs, it appears that the Misten bog water table level is the most stable one. This means that the peat forming species, present on the fagne de Clefaye and especially in the studied part of the fagne Wallonne, are constantly subjected to fluctuations (which are sometimes significant) of the water table level. Now, if the peatmosses usually spread according to a humidity gradient, some of them tolerating a greater distance of the water table level than others, it does not mean however that a same species can survive such variations. The dip wells maps and the 3-dimensional representations of the water table enable to better understand the spreading of the vegetation at the surface of the bog. But these measures also reveal the presence of pedological phenomena, natural or not, such as drainage ditches, outlet, exploitation scar, fissures in the peat mass and others, that very much influence the variation of the water table level and thereby the surface vegetation in the short-, medium-, and long-term Paleo-ecological studies In order to better understand the evolution of raised bogs and especially try to find signs of their degradation, it is essential to investigate the peat lying right under the present vegetation. All the steps that have been set about within this context tried to answer the following questions: Is there a link between the vegetation present at the surface and the recent peat composition lying right under? Is there a link between the recently formed peat composition and the water table level observed on the peat bog? Are the microfossils, that are contained in the peat, affected by variations of the water table? Can we draw differences in the composition of the peat according to how far the boring has been carried out from the current active central zone of the peat bog? It clearly appears that the composition of the peat varies according to the type of present vegetation under which the sample was taken and the range of fluctuations of the water table level recorded on this spot. On the Misten peat bog, the palynological study of peat borings 10 m away from one another allowed to show that peat layers representing the same paleobotanical event(s) do not have the same thickness in each boring and can even be absent. In the same way, at a constant rate of pollen, the accumulation speed of the peat is higher in the bog centre compared to its margins. If one considers a same paleo-botanical event, and thus a same period of time, one can see that the pollen concentration is inversely proportional to the thickness of the peat. Two distinct parts are visible on the borings of the Misten peat bog surface: the upper part, the most recent one, characterised by the influence of the topographic position of the boring on the peat forming speed; the lower part, the oldest one, in which the influence is less pronounced. Thanks to different dating techniques (l4C, pollen concentrations and reference borings), this boundary between the two parts can approximately be dated back to the middle of the 14th century. This phenomenon should be related to an anthropogenic phenomenon rather than to a climatic one, given the short distance separating the borings. It would rather be the result of the manual exploitation of the peat than the harmful effects of the Eupen ditch which was dug much later (1774). A lot of microfossils, identifiable or not, present in the borings (rhizopodes, conidia ...) can doubtless be used as degradation indicators. Of course, these studies need to be deepened and systematised before going any further. What emerges especially from these studies is that when one undertakes regeneration attempts on a peat bog, one should not only take the present vegetation and hydrological parameters into account, but also the peat structure and composition, in at least the upper part of the deposits. Research and management Although acting on the current evolution of the Belgian bogs appears essential in order to prevent them from disappearing, it is clear that restoration measures that were appropriate elsewhere, cannot be applied to other areas without some thorough knowledge of the ecological parameters that govern them. The obvious result of this work is that the scientific follow-up of the management measures that have been taken is not only imperative, but that prior study measures of the sites and their characteristics are indispensable. This type of study is heavy because it requires an important investment from the researcher and often causes a lot of damage to the studied flora and fauna. However, these studies are necessary to understand the peatland systems and should even be complemented by further studies (lysimetric, structural or chemical...) . The standardisation of the data gathering system, the improvement of the information techniques and the management of the results organised in a way that allows all the researchers to consult them should contribute towards some lightening of the work. The computer science and the miniaturised electronic technology could improve the efficiency of the measures implemented, thereby benefiting the researcher and the reserve. Given the implied advanced technologies, these modern studies and data gathering processes would be expensive but it is cheap in comparison to the costs of the heavy works that are to be undertaken in the hope of preserving the raised bogs. Moreover, such a preparation of management measures can only improve their efficiency. If, despite all the efforts, the preservation of the jewels of the state nature reserve of the Haute-Fagnes is jeopardised, these studies will at least allow to go further in the understanding of the raised bogs systems. [less ▲]

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See detailHémoglobine glyquée décentralisée
Gillery, P.; Bordas-Fonfrère, M.; Chapelle, Jean-Paul ULg et al

Poster (1999, November)

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See detailPerspective and limit of candidate gene marker’s technology in animal breeding.
Renaville, Robert ULg; Parmentier, Isabelle; Gengler, Nicolas ULg et al

in Congresso de Melhoramento Genetico (1999, November)

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See detailCompact and Portable Photorefractive Holographic Camera in View of High Accuracy and Dynamic Objects Displacements and Deformations Measurement
Georges, Marc ULg; Lemaire, Philippe

in Proceedings of the PHOTOMEC'99-ETE'99 European Workshop (1999, November)

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See detailChirurgie, radiotherapie ou hormonotherapie dans le traitement du cancer de la prostate
Bonnet, Pierre ULg; Coppens, Luc ULg; Andrianne, Robert ULg et al

in Revue Médicale de Liège (1999), 54(11), 875-85

Prostatic cancer (PC) became the first diagnosed cancer in western men and is the second leading cause of cancer death in men. Wide utilisation of serum PSA and free PSA measurements, identifies patients ... [more ▼]

Prostatic cancer (PC) became the first diagnosed cancer in western men and is the second leading cause of cancer death in men. Wide utilisation of serum PSA and free PSA measurements, identifies patients requiring transrectalultrasonography (TRUS) and TRUS guided biopsies. Most prostatic cancers diagnosed today are locally limited and may be treated by radical surgery or radiotherapy. In case of disseminated disease, hormonal manipulations remain the treatment of choice. In that field, many new drugs have been designed to allow medical castration with less complications, especially regarding sexual potency. [less ▲]

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See detailExperimental Infection of Specific Pathogen-Free New Zealand White Rabbits with Five Strains of Amyxomatous Myxoma Virus
Marlier, Didier ULg; Cassart, Dominique ULg; Boucraut-Baralon, C. et al

in Journal of Comparative Pathology (1999), 121(4), 369-84

Myxomatosis is a specific disease of the European rabbit (Oryctolagus cuniculus) due to a virus belonging to the genus Leporipoxvirus. Forty-seven years after its deliberate introduction into Europe, the ... [more ▼]

Myxomatosis is a specific disease of the European rabbit (Oryctolagus cuniculus) due to a virus belonging to the genus Leporipoxvirus. Forty-seven years after its deliberate introduction into Europe, the clinical aspects and the epizootiology of myxomatosis have changed. Two forms (nodular and amyxomatous) of the disease have been identified to date. A comparative study was made of the clinical signs, pathogenesis and gross lesions observed in male specific pathogen-free New Zealand White rabbits inoculated with five strains of amyxomatous myxoma virus. All five strains induced the characteristic amyxomatous myxomatosis clinical syndrome with clinical signs that differed only in intensity. The varying clinical intensity, together with the results of virological examination question the virulence of at least three of the five strains. Genomic analysis confirmed that the five strains came from the Lausanne strain introduced in 1952 in France and not from an unnoticed introduction of a Californian strain of myxoma virus. No link was found between the amyxomatous myxoma virus strains and the SG33 vaccine strain. 1999 Harcourt Publishers Ltd. [less ▲]

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See detailInfluence of human anti-lipopolysaccharide immunoglobulins on tissue distribution and clearance of lipopolysaccharide in rats
Nys, Monique ULg; Damas, Jacques ULg; Damas, Pierre ULg et al

in Medical Microbiology & Immunology (1999), 188(2), 65-71

To examine the influence of passive immunization on the biological fate of injected lipopolysaccharide (LPS), we used a human IgG preparation (anti-LPS IgG) rich in antibodies to a large panel of smooth ... [more ▼]

To examine the influence of passive immunization on the biological fate of injected lipopolysaccharide (LPS), we used a human IgG preparation (anti-LPS IgG) rich in antibodies to a large panel of smooth and rough purified LPS extracts as well as a normal IgG preparation (standard IgG). Our approach was to compare the uptake of 125I-labeled LPS by the tissues of saline or IgG-treated rats. After intravenous injection, one fraction of 125I-labeled Escherichia coli O55:B5 LPS is rapidly taken up by tissues, while another fraction remained in the blood. Uptake of 125I-labeled LPS was principally observed into the liver and spleen. In rats treated prophylactically with standard IgG, these tissues accumulated significantly larger amount of LPS than the tissues of rats treated with anti-LPS IgG. Nevertheless, both IgG preparations increased the specific binding of LPS by the liver and spleen. High levels of homologous unlabeled LPS decreased the uptake of LPS by the liver, presumably by occupying tissue receptors, whereas in the presence of E. coli O127:B8 LPS, an increase of the uptake of 125I-labeled LPS by the liver and lungs was observed. The pharmacokinetics and tissue distribution of LPS-IgG complexes pre-formed in vitro were compared. In the presence of standard IgG, a unexpected increase of the uptake of LPS by the tissues was recorded, whereas LPS-anti-LPS IgG complexes decreased the binding of 125I-labeled LPS to the tissues. On the other hand, the vascular effects induced by LPS did not appear to be modified in rats pretreated with either IgG preparation. In conclusion, although passive immunization against LPS slightly modified the uptake and clearance of LPS, neither in vitro nor in vivo formation of LPS-anti-LPS IgG complexes afforded a very significant protection against the toxic effects of LPS. [less ▲]

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See detailDéfinir la jeunesse ? D'un bout à l'autre du monde
Gauthier, Madeleine; Guillaume, Jean-François ULg

Book published by Les Presses de l'Université Laval (1999)

Cet ouvrage réunit des chercheurs d'un bout à l'autre du monde autour d'une même question, l'étude de la jeunesse. De quelle manière faut-il aborder cette période du cycle de vie dont on parle avec ... [more ▼]

Cet ouvrage réunit des chercheurs d'un bout à l'autre du monde autour d'une même question, l'étude de la jeunesse. De quelle manière faut-il aborder cette période du cycle de vie dont on parle avec abondance sans bien savoir comment la définir ? Les mots sont non seulement porteurs de sens, mais servent aussi à orienter l'action. Les notions d'insertion, d'intégration ou de socialisation héritées de la tradition sociologique sont aujourd'hui récupérées dans des politiques où les jeunes se sentent souvent happés. Le statut d'acteurs qu'on leur a reconnu au beau temps de l'action étudiante ne continue-t-il à s'appliquer que dans les sociétés où les jeunes sont majoritaires ? Les sociétés vieillissantes laissent-elles un peu de place aux jeunes pour l'élaboration de stratégies ? Les études qui portent aujourd'hui sur la jeunesse impliquent de démêler les intentions derrière les discours. Dans un contexte de mutation ou de (ré)invention du lien social, le pari à relever n'en est que plus passionnant. [less ▲]

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See detailStudy of the protective effects of hyperimmune immunoglobulins G and M against endotoxin in mice and rats
Nys, Monique ULg; Damas, Jacques ULg; Damas, Pierre ULg et al

in Medical Microbiology & Immunology (1999), 188(2), 55-64

We prepared solutions of human IgM and IgG to various lipopolysaccharide (LPS) species. These were then tested, along with solutions of non-LPS specific human IgG or IgM, for their ability to confer ... [more ▼]

We prepared solutions of human IgM and IgG to various lipopolysaccharide (LPS) species. These were then tested, along with solutions of non-LPS specific human IgG or IgM, for their ability to confer passive immunity against experimental endotoxemia in two animal models. The immunoglobulins were first tested for an effect on the lethality induced by seven different LPSs in actinomycin-D sensitized mice, or by three different bacteria in normal mice. When the immunoglobulins were administered 1 h before challenge, a small protective effect was observed. This protection was dependent upon both the anti-LPS agent, the chemical composition of the LPS, or the strain of gram-negative bacteria used for injection. The anti-LPS IgM and IgG preparations reduced the mortality induced by Escherichia coli but not by Serratia marcescens or Klebsiella pneumoniae, indicating protection by strain-specific antibodies. When the antibodies were preincubated with LPS or bacteria for 30 min before administration, almost complete protection was seen. The influence of these immunoglobulin preparations or of human albumin (as a control) on the hypotensive and vascular-permeabilizing effects of LPS in rats was then studied. A dose-dependent inhibitory effect was observed with IgG preparations and albumin. At 200 mg/kg, anti-LPS IgG reduced the effects of LPS, while at 400 mg/kg, both anti-LPS and normal IgG preparations showed protection, as did human albumin used at the same dose. The IgM-enriched preparation worsened the initial hypotensive phase after LPS, whereas the anti-LPS IgM significantly reduced the second phase of the hypotension, but only at the largest dose of 400 mg/kg. In this second model using the rat, a clear difference between the activity of IgG and IgM was thus observed. We conclude that pretreatment with human immunoglobulins from large plasma pools modestly, but significantly, attenuated the effects of murine and rat Gram-negative sepsis, but that protection was incomplete. Our results suggest that single regimen intervention strategies may not be sufficient to influence the course of the disease. [less ▲]

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See detailA Cell Type-Specific and Gap Junction-Independent Mechanism for the Herpes Simplex Virus-1 Thymidine Kinase Gene/Ganciclovir-Mediated Bystander Effect
Princen, Frederic; Robe, Pierre ULg; Lechanteur, Chantal ULg et al

in Clinical Cancer Research : An Official Journal of the American Association for Cancer Research (1999), 5(11), 3639-44

Tumor cells expressing the herpes simplex virus type 1 thymidine kinase (HSV-tk) gene are killed by nucleoside analogues such as ganciclovir (GCV). GCV affects not only the cells expressing HSV-tk but ... [more ▼]

Tumor cells expressing the herpes simplex virus type 1 thymidine kinase (HSV-tk) gene are killed by nucleoside analogues such as ganciclovir (GCV). GCV affects not only the cells expressing HSV-tk but also neighboring cells that do not express the gene; this phenomenon commonly is called "bystander effect." GCV metabolites transfer via gap junctional intercellular communication (GJIC) accounts for the bystander effect in different cell lines, but other mechanisms have also been described. In this study, we analyzed the mechanisms of the bystander effect in two cell lines exhibiting different capacities of communication (DHD/K12 and 9L). The 9L cells exhibited a very good bystander effect, which was completely blocked by a long-term inhibitor of GJIC, 18 alpha-glycyrrhetinic acid. DHD/K12 cells exhibited a moderate bystander effect that was not abolished by 18 alpha-glycyrrhetinic acid or 1-octanol, another strong inhibitor of GJIC. Interestingly, we also observed a bystander effect in cultures where HSV-tk-expressing DHD/K12 cells were physically separated from their untransfected counterparts but grown in the same medium. Moreover, the transfer of filtered conditioned medium from GCV-treated HSV-tk-expressing DHD/K12 cells to DHD/K12 parental cells induced a decrease of survival in a concentration-dependent manner, suggesting that the bystander effect in this cell line was mediated by a soluble factor. [less ▲]

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