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See detailLa ceinture de Kuiper fête ses 10 ans
Jancart, Sylvie ULg

in Ciel et Terre (2003), 119

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See detailCelebrazione del quotidiano
Nys-Mazure, Colette; Benzoni, Pietro ULg

Book published by Servitium (1999)

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See detailCélébrer Noël en investissant dans des choses qui ont du sens
Ozer, Pierre ULg; Perrin, Dominique ULg

Article for general public (2011)

Le contexte de crises financière et environnementale préoccupantes que nous traversons devrait nous convaincre de modifier nos comportements d’achat. Les fêtes de fin d’année peuvent être l’occasion de ... [more ▼]

Le contexte de crises financière et environnementale préoccupantes que nous traversons devrait nous convaincre de modifier nos comportements d’achat. Les fêtes de fin d’année peuvent être l’occasion de consommer différemment, en considérant d’abord la « valeur » des choses avant leur « prix ». [less ▲]

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See detail« La Célestine, médiatrice temporelle de ses réécritures »
Francois, Jeromine ULg

Conference (2015)

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See detailCELINE : CELestial Infrared Nulling Experiment
Hanot, Charles ULg

Scientific conference (2010, February)

The small angular distance (<100 mas) and the huge flux ratio (10^7) between an Earth-like exoplanet in the so-called habitable zone and its host star makes it very difficult to direct image such systems ... [more ▼]

The small angular distance (<100 mas) and the huge flux ratio (10^7) between an Earth-like exoplanet in the so-called habitable zone and its host star makes it very difficult to direct image such systems. Nulling interferometry consists of a very powerful technique that combines destructively the light from two or more collectors to dim the starlight and to reveal faint companions in its vicinity. We have developed a new nulling experiment based on the fiber nuller principle (Serabyn et al. 2006 , Martin et al. 2008). This fully symmetric reflective nulling bench aims at testing broadband nulling in both H and K bands as well as characterizing photonic fibers for modal filtering. We present in this paper the design, the development as well as preliminary results of the experiment. [less ▲]

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See detailCell "circadian" cycle: new role for mammalian core clock genes.
Borgs, Laurence ULg; Beukelaers, Pierre ULg; Vandenbosch, Renaud ULg et al

in Cell Cycle (Georgetown, Tex.) (2009), 8(6), 832-7

In mammals, 24 hours rhythms are organized as a biochemical network of molecular clocks that are operative in all tissues, with the master clock residing in the hypothalamic suprachiasmatic nucleus (SCN ... [more ▼]

In mammals, 24 hours rhythms are organized as a biochemical network of molecular clocks that are operative in all tissues, with the master clock residing in the hypothalamic suprachiasmatic nucleus (SCN). The core pacemakers of these clocks consist of auto-regulatory transcriptional/post-transcriptional feedback loops. Several lines of evidence suggest the existence of a crosstalk between molecules that are responsible for the generation of circadian rhythms and molecules that control the cell cycle progression. In addition, highly specialized cell cycle checkpoints involved in DNA repair after damage seem also, at least in part, mediated by clock proteins. Recent studies have also highlighted a putative connection between clock protein dysfunction and cancer progression. This review discusses the intimate relation that exists between cell cycle progression and components of the circadian machinery. [less ▲]

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See detailCell based advanced therapeutic medicinal products for bone repair: Keep it simple?
Leijten, J.; Chai, Y. C.; Papantoniou, I. et al

in Advanced drug delivery reviews (2015), 84

The development of cell based advanced therapeutic medicinal products (ATMPs) for bone repair has been expected to revolutionize the health care system for the clinical treatment of bone defects. Despite ... [more ▼]

The development of cell based advanced therapeutic medicinal products (ATMPs) for bone repair has been expected to revolutionize the health care system for the clinical treatment of bone defects. Despite this great promise, the clinical outcomes of the few cell based ATMPs that have been translated into clinical treatments have been far from impressive. In part, the clinical outcomes have been hampered because of the simplicity of the first wave of products. In response the field has set-out and amassed a plethora of complexities to alleviate the simplicity induced limitations. Many of these potential second wave products have remained "stuck" in the development pipeline. This is due to a number of reasons including the lack of a regulatory framework that has been evolving in the last years and the shortage of enabling technologies for industrial manufacturing to deal with these novel complexities. In this review, we reflect on the current ATMPs and give special attention to novel approaches that are able to provide complexity to ATMPs in a straightforward manner. Moreover, we discuss the potential tools able to produce or predict 'goldilocks' ATMPs, which are neither too simple nor too complex. [less ▲]

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See detailA cell based modelling framework for skeletal tissue engineering applications
Geris, Liesbet ULg; Van Liedekerke, Paul; Smeets, Bart et al

in Journal of Biomechanics (2010), 43(5), 887-892

In this study, a cell based lattice free modelling framework is proposed to study cell aggregate behaviour in bone tissue engineering applications. The model encompasses cell-to-cell and cell environment ... [more ▼]

In this study, a cell based lattice free modelling framework is proposed to study cell aggregate behaviour in bone tissue engineering applications. The model encompasses cell-to-cell and cell environment interactions such as adhesion, repulsion and drag forces. Oxygen, nutrients, waste products, growth factors and inhibitors are explicitly represented in the model influencing cellular behaviour. Furthermore, a model for cell metabolism is incorporated representing the basic enzymic reactions of glycolysis and the Krebs cycle. Various types of cell death such as necrosis, apoptosis and anoikis are implemented. Finally, an explicit model of the cell cycle controls the proliferation process, taking into account the presence or absence of various metabolites, sufficient space and mechanical stress. Several examples are presented demonstrating the potential of the modelling framework. The behaviour of a synchronised cell aggregate under ideal circumstances is simulated, clearly showing the different stages of the cell cycle and the resulting growth of the aggregate. Also the difference in aggregate development under ideal (normoxic) and hypoxic conditions is simulated, showing hypoxia induced necrosis mainly in the centre of the aggregate grown under hypoxic conditions. The next step in this research will be the application of this modelling framework to specific experimental set-ups for bone tissue engineering applications. (C) 2009 Elsevier Ltd. All rights reserved. [less ▲]

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See detailCell cholesterol modulates metalloproteinase-dependent shedding of low-density lipoprotein receptor-related protein-1 (LRP-1) and clearance function.
Selvais, C.; D'Auria, L.; Tyteca, D. et al

in FASEB Journal (2011), 25(8), 2770-2781

Low-density lipoprotein receptor-related protein-1 (LRP-1) is a plasma membrane scavenger and signaling receptor, composed of a large ligand-binding subunit (515-kDa α-chain) linked to a shorter ... [more ▼]

Low-density lipoprotein receptor-related protein-1 (LRP-1) is a plasma membrane scavenger and signaling receptor, composed of a large ligand-binding subunit (515-kDa α-chain) linked to a shorter transmembrane subunit (85-kDa β-chain). LRP-1 cell-surface level and function are controlled by proteolytic shedding of its ectodomain. Here, we identified ectodomain sheddases in human HT1080 cells and demonstrated regulation of the cleavage by cholesterol by comparing the classical fibroblastoid type with a spontaneous epithelioid variant, enriched ∼2-fold in cholesterol. Two membrane-associated metalloproteinases were involved in LRP-1 shedding: a disintegrin and metalloproteinase-12 (ADAM-12) and membrane-type 1 matrix metalloproteinase (MT1-MMP). Although both variants expressed similar levels of LRP-1, ADAM-12, MT1-MMP, and specific tissue inhibitor of metalloproteinases-2 (TIMP-2), LRP-1 shedding from epithelioid cells was ∼4-fold lower than from fibroblastoid cells. Release of the ectodomain was triggered by cholesterol depletion in epithelioid cells and impaired by cholesterol overload in fibroblastoid cells. Modulation of LRP-1 shedding on clearance was reflected by accumulation of gelatinases (MMP-2 and MMP-9) in the medium. We conclude that cholesterol exerts an important control on LRP-1 levels and function at the plasma membrane by modulating shedding of its ectodomain, and therefore represents a novel regulator of extracellular proteolytic activities.-Selvais, C., D'Auria, L., Tyteca, D., Perrot, G, Lemoine, P., Troeberg, L., Dedieu, S., Noël, A., Nagase, H., Henriet, P., Courtoy, P. J., Marbaix, E., Emonard, H. Cell cholesterol modulates metalloproteinase-dependent shedding of low-density lipoprotein receptor-related protein-1 (LRP-1) and clearance function. [less ▲]

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See detailCell cultivation in chitosan alginate hydrogel beads
Henrotin, Yves ULg; Kesteloot, Frédéric; Sanchez, Christelle ULg

Patent (2014)

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See detailCell cultivation in chitosan alginate hydrogel beads
Henrotin, Yves ULg; Kesteloot, Frédéric; Sanchez, Christelle ULg

Patent (2011)

The present invention relates to a method of producing a hydrogel matrix comprising cartilage-forming cells wherein alginate, chitosan and cartilage-forming cells are mixed and subsequently polymerised ... [more ▼]

The present invention relates to a method of producing a hydrogel matrix comprising cartilage-forming cells wherein alginate, chitosan and cartilage-forming cells are mixed and subsequently polymerised into beads. [less ▲]

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See detailCELL CULTIVATION IN CHITOSAN ALGINATE HYDROGEL BEADS
Henrotin, Yves ULg; Kesteloot, Frédéric; Sanchez, Christelle ULg

Patent (2011)

The present invention relates to a method of producing a hydrogel matrix comprising cartilage-forming cells wherein alginate, chitosan and cartilage- forming cells are mixed and subsequently polymerised ... [more ▼]

The present invention relates to a method of producing a hydrogel matrix comprising cartilage-forming cells wherein alginate, chitosan and cartilage- forming cells are mixed and subsequently polymerised into beads. [less ▲]

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See detailCell cycle activation of hematopoietic progenitor cells increases very late antigen-5-mediated adhesion to fibronectin.
Giet, Olivier ULg; Huygen, Sandra; Beguin, Yves ULg et al

in Experimental hematology (2001), 29(4), 515-24

Recent studies suggested that trafficking of hematopoietic progenitor cells is related to cell cycle status. We studied whether adhesion of progenitor cells to extracellular matrix proteins was modulated ... [more ▼]

Recent studies suggested that trafficking of hematopoietic progenitor cells is related to cell cycle status. We studied whether adhesion of progenitor cells to extracellular matrix proteins was modulated by cell cycle transit.Mobilized peripheral blood CD34+ cells were stimulated ex vivo for 48 hours with stem cell factor, flt-3 ligand, and thrombopoietin and fractionated by adhesion to fibronectin or vascular cell adhesion molecule-1 (VCAM-1). Adherent and nonadherent cells were assayed for cell cycle status, long-term culture-initiating cell frequency, and integrin function. Binding to fibronectin, but not to VCAM-1, displayed a cell cycle selectivity as the adherent fraction to fibronectin was enriched in cycling CD34+ cells and in cycling long-term culture-initiating cells compared to the nonadherent fraction. Combined cell cycle and phenotypic analysis showed that the expression of VLA-5 was upregulated during S/G2+M but that of VLA-4 remained constant. The selective binding of cycling CD34+ cells to fibronectin was reverted by anti-VLA-5 but not by anti-VLA-4 blocking antibodies. Also, cycling CD34+ cells preferentially adhered to the VLA-5 binding domain but not to the VLA-4 binding domain of fibronectin. Adhesion of cycling CD34+ cells to fibronectin was a reversible process modulated by cell cycle progression, because adherent cells could exit the cell cycle and return to a nonadhesive state within an additional 48-hour culture period.The results indicate that the enhanced binding capacity of cycling progenitor cells to fibronectin is mediated by VLA-5. [less ▲]

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See detailCell cycle duration at the time of maternal zygotic transition for in vitro produced bovine embryos: effect of oxygen tension and transcription inhibition.
Lequarré, Anne-Sophie ULg; Marchandise, J.; Massip, A. et al

in Biology of Reproduction (2003), 69(5), 1707-13

Early embryonic cleavages are mostly regulated by maternal components then control of development progressively depends on newly synthesized zygotic products. The timing of the first cleavages is a way to ... [more ▼]

Early embryonic cleavages are mostly regulated by maternal components then control of development progressively depends on newly synthesized zygotic products. The timing of the first cleavages is a way to assess embryo quality. The goal of this study was to evaluate the duration of the fourth cell cycle, at the time of maternal-to-zygotic transition (MZT) in in vitro-produced bovine embryos by means of cinematographic analysis. We found that 75% of the embryos displayed a long fourth cycle (43.5 +/- 5.4 h) whereas the remaining embryos had a very short fourth cell cycle (8.9 +/- 2.9 h). Both groups did not differ in cleavage rhythm up to the eight-cell stage and timing of cavitation and blastocyst expansion was identical. However, embryos with a short fourth cell cycle had a better blastocyst rate than embryos with a long cycle (59% versus 38%, P < 0.01). Total cell number, inner cell mass (ICM):total cell ratio, and hatching rate were identical for blastocysts produced from embryos with either a long or a short fourth cell cycle. In a second experiment, we showed that increasing the oxygen tension, from 5% to 20%, decreased the percentage of embryos with a short fourth cell cycle, from 25% to 11% (P < 0.01), indicating that suboptimal culture conditions can influence the length of this cycle. Finally, we investigated whether fourth cell cycle duration could be influenced by transcription inhibition. With alpha-amanitin added at 18 h postinsemination (HPI), cleavage was reduced (66% versus 79%) and, at 70 HPI, the 9- to 16-cell rate increased (50% versus 25%) concomitantly with a 5- to 8-cell rate decrease (16% versus 47%). A similar pattern was observed when the drug was added at 6 HPI or 42 HPI but not at 0 HPI. Cinematographic analysis revealed that alpha-amanitin increased the first cell cycle duration whereas the second and third cell cycles were not affected. With the drug, one third of the embryos could develop up to the 9- to 16-cell stage and they all had a short fourth cell cycle (11.2 +/- 3.7 h) with a good synchrony of cleavage between blastomeres. These results suggest that duration of the fourth cell cycle of bovine embryo, during the MZT, is under a zygotic transcriptional control that can be affected by oxidative conditions. [less ▲]

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See detailCell cycle-related changes in repopulating capacity of human mobilized peripheral blood CD34(+) cells in non-obese diabetic/severe combined immune-deficient mice.
GOTHOT, André ULg; Van der loo, J. C. M.; Clapp, D. W. et al

in Blood (1998), 92(8), 2641-9

Most primitive hematopoietic progenitor cells reside in vivo within the G0/G1 phase of the cell cycle. By simultaneous DNA/RNA staining it is possible to distinguish G0 and G1 states and to isolate cells ... [more ▼]

Most primitive hematopoietic progenitor cells reside in vivo within the G0/G1 phase of the cell cycle. By simultaneous DNA/RNA staining it is possible to distinguish G0 and G1 states and to isolate cells in defined phases of the cell cycle. We report here the use of cell cycle fractionation to separate human mobilized peripheral blood (MPB) CD34(+) cells capable of repopulating the bone marrow (BM) of non-obese diabetic/severe combined immune-deficient (NOD/SCID) mice. In freshly isolated MPB, repopulating cells were predominant within the G0 phase, because transplantation of CD34(+) cells residing in G0 (G0CD34(+)) resulted on average in a 16.6- +/- 3.2-fold higher BM chimerism than infusion of equal numbers of CD34(+) cells isolated in G1. We then investigated the effect of ex vivo cell cycle progression, in the absence of cell division, on engraftment capacity. Freshly isolated G0CD34(+) cells were activated by interleukin-3 (IL-3), stem cell factor (SCF), and flt3-ligand (FL) for a 36-hour incubation period during which a fraction of cells progressed from G0 into G1 but did not complete a cell cycle. The repopulating capacity of stimulated cells was markedly diminished compared with that of unmanipulated G0CD34(+) cells. Cells that remained in G0 during the 36-hour incubation period and those that traversed into G1 were sorted and assayed separately in NOD/SCID recipients. The repopulating ability of cells remaining in G0 was insignificantly reduced compared with that of unstimulated G0CD34(+) cells. On the contrary, CD34(+) cells traversing from G0 into G1 were largely depleted of repopulating capacity. Similar results were obtained when G0CD34(+) cells were activated by the combination of thrombopoietin-SCF-FL. These studies provide direct evidence of the quiescent nature of cells capable of repopulating the BM of NOD/SCID mice. Furthermore, these data also demonstrate that G0-G1 progression in vitro is associated with a decrease in engraftment capacity. [less ▲]

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See detailCell death and growth arrest in response to photodynamic therapy with membrane-bound photosensitizers
Piette, Jacques ULg; Volanti, Cédric ULg; Vantieghem, Annelies et al

in Biochemical Pharmacology (2003), 66(8), 1651-1659

Photodynamic therapy (PDT) is a treatment for cancer and for certain benign conditions that is based on the use of a photosensitizer and light to produce reactive oxygen species in cells. Many of the ... [more ▼]

Photodynamic therapy (PDT) is a treatment for cancer and for certain benign conditions that is based on the use of a photosensitizer and light to produce reactive oxygen species in cells. Many of the photosensitizers currently used in PDT localize in different cell compartments such as mitochondria, lysosomes, endoplasmic reticulum and generate cell death by triggering necrosis and/or apoptosis. Efficient cell death is observed when light, oxygen and the photosensitizer are not limiting ("high dose PDT"). When one of these components is limiting ("low dose PDT"), most of the cells do not immediately undergo apoptosis or necrosis but are growth arrested with several transduction pathways activated. This commentary will review the mechanism of apoptosis and growth arrest mediated by two important PDT agents. i.e. pyropheophorbide and hypericin. (C) 2003 Elsevier Inc. All rights reserved. [less ▲]

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See detailCell dynamics and immune response to BLV infection: a unifying model
Florins, Arnaud-Francois ULg; Gillet, Nicolas ULg; Asquith, Becca et al

in Frontiers in Bioscience : A Journal and Virtual Library (2007), 12

Bovine Leukemia virus (BLV) is the natural etiological agent of a lymphoproliferative disease in cattle. BLV can also be transmitted experimentally to a related ruminant species, sheep, in which the ... [more ▼]

Bovine Leukemia virus (BLV) is the natural etiological agent of a lymphoproliferative disease in cattle. BLV can also be transmitted experimentally to a related ruminant species, sheep, in which the pathogenesis is more acute. Although both susceptible species develop a strong anti-viral immune response, the virus persists indefinitely throughout life, apparently at a transcriptionally silent stage, at least in a proportion of infected cells. Soon after infection, these humoral and cytotoxic activities very efficiently abolish the viral replicative cycle, permitting only mitotic expansion of provirus-carrying cells. Short term cultures of these infected cells initially indicated that viral expression protects against spontaneous apoptosis, suggesting that leukemia is a process of accumulation of long-lived cells. This conclusion was recently reconsidered following in vivo dynamic studies based on perfusions of nucleoside (bromodeoxyuridine) or fluorescent protein markers (CFSE). In sheep, the turnover rate of infected cells is increased, suggesting that a permanent clearance process is exerted by the immune system. Lymphocyte trafficking from and to the secondary lymphoid organs is a key component in the maintenance of cell homeostasis. The net outcome of the immune selective pressure is that only cells in which the virus is transcriptionally silenced survive and accumulate, ultimately leading to lymphocytosis. Activation of viral and/or cellular expression in this silent reservoir with deacetylase inhibitors causes the collapse of the proviral loads. In other words, modulation of viral expression appears to be curative in lymphocytic sheep, an approach that might also be efficient in patients infected with the related Human T-lymphotropic virus type 1. In summary, a dynamic interplay between BLV and the host immune response modulates a complex equilibrium between (i) viral expression driving (or) favoring proliferation and (ii) viral silencing preventing apoptosis. As conclusion, we propose a hypothetical model unifying all these mechanisms. [less ▲]

Detailed reference viewed: 246 (45 ULg)