References of "Peulen, Olivier"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailTransferts graisseux au niveau du sein: implications oncologiques.
NIZET, Jean-Luc ULg; Gonzalez, Arnaud ULg; Peulen, Olivier ULg et al

in Revue Médicale de Liège (2011), 66(5-6), 362-6

Autologous fat grafting for breast is increasing dramatically. This fat injection needs accurate technical conditions, and shows very good and long-lasting clinical results. Nevertheless, in breast ... [more ▼]

Autologous fat grafting for breast is increasing dramatically. This fat injection needs accurate technical conditions, and shows very good and long-lasting clinical results. Nevertheless, in breast conservative treatment sequellae, fat injection could lead to difficulties in breast imaging, but also there is some concerns about the potential oncologic risks of these procedures. [less ▲]

Detailed reference viewed: 81 (10 ULg)
Full Text
Peer Reviewed
See detailCellular uptake of liposomes monitored by confocal microscopy and flow cytometry
Ducat, Emilie ULg; Evrard, Brigitte ULg; Peulen, Olivier ULg et al

in Journal of Drug Delivery Science and Technology [=JDDST] (2011), 21(6), 469-477

Detailed reference viewed: 130 (29 ULg)
Full Text
Peer Reviewed
See detailCellular uptake of long-circulating pH-sensitive liposomes: evaluation of the liposome and its encapsulated material penetration in cancer cells
Ducat, Emilie ULg; Deprez, Julie ULg; Peulen, Olivier ULg et al

in Drug Discovery Today (2010, December), 15(23-24), 1079-1114

Print 3G, a peptidic antagonist of oncoprotein involved in breast cancer, could reduce the angiogenic development of breast tumors, leading to tumor dormancy. The necessity of intravenous administration ... [more ▼]

Print 3G, a peptidic antagonist of oncoprotein involved in breast cancer, could reduce the angiogenic development of breast tumors, leading to tumor dormancy. The necessity of intravenous administration of Print 3G led to the development of long-circulating liposomes as drug carriers. Pegylated liposomes, too large to be collected by fenestrated organs, accumulate passively in solid tumors thanks to the EPR effect. The strategy was to combine the protective properties of PEG with the transfection properties of pH-sensitive lipids which could promote the uptake of liposomes by cells and avoid lysosomal sequestration and degradation of entrapped materials such as peptides. In this study, we compare two formulations in terms of cellular uptake using confocal microscopy. The first one is composed of SPC:CHOL:mPEG-750-DSPE (47:47:6), used as "standard" liposomes, and the second one of DOPE:CHEMS:CHOL:mPEG750-DSPE (43:21:30:6), used as pH-sensitive liposomes. First, we evaluated the penetration of an encapsulated model molecule, calcein, in Hs578t human breast cancer epithelial cells. When calcein was encapsulated in standard liposomes, its penetration was effective only in few cells. On the contrary, a majority of cells were fluorescent when calcein-loaded pH-sensitive liposomes were applied for 3 hours on cells. Secondly, we studied the penetration of liposomes themselves in Hs578t cells using 25-[(nitrobenzoxadiazolyl)methylamino]nor-cholesterol (NBD-CHOL) as a fluorescent marker of the phospholipid membrane. The obtained results were comparable to those obtained with calcein: a higher penetration of liposome was observed for pH-sensitive liposomes. Finally, the cellular uptake of liposomes using both NBD-CHOL and rhodamine encapsulated in the inner cavity of vesicles was evaluated with Hs578t cells and compared with WI26 human diploid lung fibroblast cells. Thanks to this experiment, we could follow simultaneously the cell distribution of the encapsulated material and of the liposome itself. Confocal pictures obtained with pH-sensitive liposomes on both WI26 and Hs578t cells allow us to visualize the co-localized red and green colors of rhodamine and NBD-CHOL, with a higher concentrated area near the nucleus. In comparison with "standard" liposomes, we observed a higher penetration of the encapsulated material and of the liposome itself in breast cancer cells. Moreover, we visualized a colocalization near the nucleus of liposomes components. Concerning results obtained with fibroblastic cells, there was no difference in terms of cellular uptake between the two formulations. In perspective, we would like to compare these results, obtained with model molecules, with experiments performed with biotinylated Print 3G to assess its cellular distribution. Moreover, it would be interesting to correlate results obtained with confocal microscopy with a possible increase of the peptide efficacy against cancer cells when it is encapsulated in long-circulating pH-sensitive liposomes. [less ▲]

Detailed reference viewed: 175 (37 ULg)
Full Text
Peer Reviewed
See detailPEPTIDE-LOADED LIPOSOMES AGAINST BREAST CANCER: EFFECTIVE PENETRATION IN CELLS OF LONG CIRCULATING pH-SENSITIVE VESICLES
Ducat, Emilie ULg; Deprez, Julie ULg; Peulen, Olivier ULg et al

Poster (2010, October)

Purpose: Print3G, a peptidic antagonist of oncoprotein involved in breast cancer, could reduce the angiogenic development of breast tumors. The necessity of intravenous administration of Print3G led to ... [more ▼]

Purpose: Print3G, a peptidic antagonist of oncoprotein involved in breast cancer, could reduce the angiogenic development of breast tumors. The necessity of intravenous administration of Print3G led to the development of liposomes as drug carriers, combining the protective properties of PEG with the transfection properties of pH-sensitive lipids. The purpose of this work is to compare pegylated pH-sensitive liposomes with a classical formulation of long-circulating liposomes in terms of cellular uptake. Methods: Classical liposomes (SPC:CHOL:mPEG-750-DSPE (47:47:6 mol/mol)) and pH-sensitive liposomes (DOPE:CHEMS:CHOL: mPEG750-DSPE (43:21:30:6 mol/mol)) were compared in terms of size, charge, stability, pH-sensitivity and toxicity by inhibition of cell proliferation. Finally, confocal microscopy was used to study the cellular uptake of liposomes by three cell lines (Hs578t, WI-26 and MDA-MB-231), using 25-nitrobenzoxydiazol-cholesterol as a fluorescent marker of the vesicular membrane and rhodamine in the inner cavity of liposomes. Results: Sizes of 162.8 ± 4.6 nm and zeta potential of -9.3 ± 1.2 mV were obtained for standard liposomes (n=3) while the obtained values for pH-sensitive liposomes (n=3) were respectively of 184.8 ± 3.2 nm and -19.5 ± 2.6 mV. The two formulations were comparable in terms of shape and stability. Concerning the pH-sensitivity study, a significantly higher leakage of the encapsulated material was observed at pH 5 for pH-sensitive liposomes. Confocal pictures obtained with these vesicles on the three cell lines allowed us to visualize the colocalized red and green color with a higher concentration near the nucleus. Conclusion: Long circulating pH-sensitive liposomes are promising drug delivery systems in terms of cellular uptake. Experiments will be performed with biotinylated Print3G to assess its cellular distribution. Moreover, the accumulation of this formulation in breast tumor will be evaluated by in vivo studies. [less ▲]

Detailed reference viewed: 62 (8 ULg)
Full Text
Peer Reviewed
See detailSoluble forms of VEGF receptor-1 and -2 promote vascular maturation via mural cell recruitment.
LORQUET, Sophie ULg; Berndt, Sarah; Blacher, Silvia ULg et al

in FASEB Journal (2010), 24(10), 3782-95

Two soluble forms of vascular endothelial growth factor (VEGF) receptors, sVEGFR-1 and sVEGFR-2, are physiologically released and overproduced in some pathologies. They are known to act as anti-VEGF ... [more ▼]

Two soluble forms of vascular endothelial growth factor (VEGF) receptors, sVEGFR-1 and sVEGFR-2, are physiologically released and overproduced in some pathologies. They are known to act as anti-VEGF agents. Here, we report that these soluble receptors contribute to vessel maturation by mediating a dialogue between endothelial cells (EC) and mural cells that leads to blood vessel stabilization. Through a multidisciplinary approach, we provide evidences that these soluble VEGF receptors promote mural cell migration through a paracrine mechanism involving interplay in EC between VEGF/VEGFR-2 and sphingosine-1- phosphate type-1 (S1P)/S1P1 pathways that leads to endothelial nitric oxyde synthase (eNOS) activation. This new paradigm is supported by the finding that sVEGFR-1 and -2: 1) induce an eNOS-dependent outgrowth of a mural cell network in an ex vivo model of angiogenesis, 2) increase the mural cell coverage of neovessels in vitro and in vivo, 3) promote mural cell migration towards EC, 4) stimulate endothelial S1P1 overproduction and eNOS activation that promote the migration and the recruitment of neighboring mural cells. These findings provide new insights into mechanisms regulating physiological and pathological angiogenesis and vessel stabilization. [less ▲]

Detailed reference viewed: 144 (44 ULg)
See detailPhysiologie Digestive
Khan, Naim Akhtar; Roman, Sabine; Peulen, Olivier ULg et al

in Guénard, Hervé (Ed.) Physiologie Humaine (2009)

Detailed reference viewed: 111 (3 ULg)
See detailGuide des Travaux Pratiques de Biologie
Peulen, Olivier ULg; Detry, Cédric ULg; Lamour, Virginie ULg et al

Learning material (2009)

Detailed reference viewed: 306 (70 ULg)
Peer Reviewed
See detail1H NMR metabolomic approach of the laser-induced choroidal neovascularization in mice
Lambert, Vincent ULg; Frederich, Michel ULg; Rousseau, Rousseau et al

Poster (2008, August)

Detailed reference viewed: 65 (33 ULg)
Full Text
Peer Reviewed
See detailThe lymphatic ring assay: a 3D-culture model of lymphangiogenesis.
Bruyere, Françoise ULg; Melen-Lamalle, Laurence ULg; Berndt, Sarah ULg et al

in Nature Protocols (2008)

Lymphangiogenesis, the formation of new lymphatic vessels, is associated to numerous pathologies1 and understanding the molecular and cellular basis of this complex process is essential for the ... [more ▼]

Lymphangiogenesis, the formation of new lymphatic vessels, is associated to numerous pathologies1 and understanding the molecular and cellular basis of this complex process is essential for the development of novel therapeutic strategies. Studies on lymphangiogenesis have been hampered by difficulties in culturing lymphatic capillaries as three-dimensional (3D) structures in vitro that mimic the in vivo features of lymphatic vessels and lymphangiogenesis. The lymphatic ring assay described here phenocopies the different steps of lymphangiogenesis, including the spreading from a preexisting vessel, cell proliferation, migration and differentiation into capillaries. It consists on the adaptation of the aortic ring assay that has proved to be useful to investigate the molecular basis of angiogenesis2-4. The lymphatic ring model is an ideal assay for testing the activity of lymphangiogenic agonists or antagonists. The absence of inflammatory cells allows a simple interpretation of results and the determination of direct effects of compounds on lymphatic endothelial cell properties. Another advantage of the lymphatic ring assay is that cell outgrowing are primary cells which have not been modified by repeated passages or immortalization. This culture model bridges the gap between in vitro and in vivo studies and allows genetic analysis by using thoracic ducts from genetically modified mice. [less ▲]

Detailed reference viewed: 212 (31 ULg)
Full Text
Peer Reviewed
See detailStudy on the effects of laminarin, a polysaccharide from seaweed, on gut characteristics
Deville, Christelle ULg; Gharbi, Myriam ULg; Dandrifosse, Guy ULg et al

in Journal of the Science of Food and Agriculture (2007), 87(9), 1717-1725

This study investigates whether laminarin (beta 1-3,beta 1-6-glucan), a polysaccharide from seaweed, exhibits beneficial properties for human health by analysing its effects on intestinal parameters ... [more ▼]

This study investigates whether laminarin (beta 1-3,beta 1-6-glucan), a polysaccharide from seaweed, exhibits beneficial properties for human health by analysing its effects on intestinal parameters. Anaerobic batch culture fermenters were used for the screening of the in vitro utilization of laminarin by the human gut microflora through the monitoring of biochemical and microbiological parameters. Additionally, the influence of laminarin ingestion on the composition of intestinal mucus (neutral mucins, sialomucins and sulphomucins) was studied in rats. Laminarin was almost totally (more than 90% used) fermented after 24 h of incubation with human intestinal bacteria. It was not selectively used by bifidobacteria and lactobacilli, but increased the production of propionate and butyrate. Variations of mucus composition were observed in jejunum, ileum, caecum and colon, both in lumen content and in intestinal wall, of rats after ingestion of this polysaccharide. Due to its effects on mucus composition, laminarin could influence the adherence and the translocation of bacteria across the epithelial wall. In conclusion, laminarin seems to be a modulator of the intestinal metabolism by its effects on mucus composition, intestinal pH and short chain fatty acid (SCFA) production, especially butyrate. (c) 2007 Society of Chemical Industry. [less ▲]

Detailed reference viewed: 175 (9 ULg)
Full Text
Peer Reviewed
See detailApoptosis and cytolysis induced by giganteosides and hederacolchisides in HL-60 cells
Gerkens, Pascal; Dobson, Rowan ULg; tabatadze, Nino et al

in Anticancer Research (2007), 27

The viability, cytolysis and apoptosis-mediated cellular death induced by giganteosides D and E (Gig-D and Gig-E) and hederacolchisides A and A1 (Hcol-A and Hcol- A1) were analysed in HL-60 cells ... [more ▼]

The viability, cytolysis and apoptosis-mediated cellular death induced by giganteosides D and E (Gig-D and Gig-E) and hederacolchisides A and A1 (Hcol-A and Hcol- A1) were analysed in HL-60 cells. Materials and Methods: the end-point metabolic (WST1) and lactate dehydrogenase (LDH) assays were used. Cell cycle analysis and apoptosis were measured by flow cytometry, DNA laddering and caspase 3 analyses. Results: the HL-60 cell line was more sensitive to Hcol-A1 and Gig-D (IC50 3-5 ÌM) than to Gig-E and Hcol-A (IC50 8-13 ÌM; WST1 assay). This was related to LDH release. The induction of apoptosis could be detected without caspase 3 activation after 24 h of treatment. DNA fragmentation could be detected only with Gig-D. With Hcol- A1 and Gig-D, an accumulation of cells in the S-phase and an increase of cells in sub-G1 peak were observed. By the annexinV-fluorescein isothiocyanate (FITC)/7-aminoactinomycin D (AAD) assay, the majority of cells were in late apoptosis with Gig-D, and in necrosis with Hcol-A1. Conclusion: Hcol-A1 is more cytotoxic than Gig-D, followed by Gig-E and finally Hcol-A. This is related to a membrane permeabilization effect, leading to cytolysis [less ▲]

Detailed reference viewed: 55 (11 ULg)
See detailEléments de bioinformatique v3.0
Peulen, Olivier ULg

Learning material (2007)

Detailed reference viewed: 23 (9 ULg)
See detailBiologie du système digestif et nutrition
Peulen, Olivier ULg

Learning material (2007)

Detailed reference viewed: 31 (2 ULg)
Full Text
Peer Reviewed
See detailDevelopment of a serum-free co-culture of human intestinal epithelium cell-lines (Caco-2/HT29-5M21)
Nollevaux, Géraldine; Deville, Christelle ULg; Elmoualij, Benaïssa ULg et al

in BMC Cell Biology (2006), 7

Background: The absorptive and goblet cells are the main cellular types encountered in the intestine epithelium. The cell lineage Caco-2 is a model commonly used to reproduce the features of the bowel ... [more ▼]

Background: The absorptive and goblet cells are the main cellular types encountered in the intestine epithelium. The cell lineage Caco-2 is a model commonly used to reproduce the features of the bowel epithelium. However, there is a strong debate regarding the value of Caco-2 cell culture to mimick in vivo situation. Indeed, some authors report in Caco-2 a low paracellular permeability and an ease of access of highly diffusible small molecules to the microvilli, due to an almost complete lack of mucus. The HT29-5M21 intestinal cell lineage is a mucin-secreting cellular population. A co-culture system carried out in a serum-free medium and comprising both Caco-2 and HT29-5M21 cells was developed. The systematic use of a co-culture system requires the characterization of the monolayer under a given experimental procedure. Results: In this study, we investigated the activity and localization of the alkaline phosphatase and the expression of IAP and MUC5AC genes to determine a correlation between these markers and the cellular composition of a differentiated monolayer obtained from a mixture of Caco-2 and HT29-5M21 cells. We observed that the culture conditions used ( serum-free medium) did not change the phenotype of each cell type, and produced a reproducible model. The alkaline phosphatase expression characterizing Caco-2 cells was influenced by the presence of HT29-5M21 cells. Conclusion: The culture formed by 75% Caco-2 and 25% HT29-5M21 produce a monolayer containing the two main cell types of human intestinal epithelium and characterized by a reduced permeability to macromolecules. [less ▲]

Detailed reference viewed: 56 (8 ULg)
Peer Reviewed
See detailIn vitro transport studies of nifedipine nanoparticles across Caco-2/HT29- 5M21 cultures and co-cultures
Hecq, Julien; Nollevaux, Géraldine; Deleers, M. et al

Poster (2006)

Detailed reference viewed: 42 (6 ULg)
Full Text
Peer Reviewed
See detailNifedipine nanocrystals: pharmacokinetic evaluation in the rat and permeability studies in Caco-2/HT29-5M21 (co)-cultures
Hecq, Julien; Nollevaux, Géraldine; Deleers, M. et al

in Journal of Drug Delivery Science and Technology (2006), 16(6, NOV-DEC), 437-442

Poorly water-soluble drugs such as nifedipine (NIF) (similar to 20 mu g/mL) offer challenging problems in drug formulation as poor solubility is generally associated with poor dissolution characteristics ... [more ▼]

Poorly water-soluble drugs such as nifedipine (NIF) (similar to 20 mu g/mL) offer challenging problems in drug formulation as poor solubility is generally associated with poor dissolution characteristics and thus with poor oral bioavailability (BCS class H drugs). In order to enhance these characteristics, formulation of NIF as nanocrystals was carried out. NIF nanoparticles (NP) were prepared using high-pressure homogenization (HPH). Solubility and dissolution characteristics have been reported in previous work to be significantly enhanced for NIF NP. Influence of NIF particle size on NIF permeation rate across intestinal cell models (Caco-2 and HT29-5M21 cultures and co-cultures) was investigated in order to complement these promising in vitro data. Apical to basolateral transfer studies were carried out across Caco-2 and HT29-5M21 cultures and co-cultures. Caco-2/HT29-5M21 co-cultures (seeding ratio 3: 1) were evaluated to better represent in vivo intestinal conditions. The influence of chitosan in the NIF NP formulation with regard to in vitro NIF permeation rate was also evaluated. These studies showed that NIF permeation rate across the different in vitro models evaluated can be significantly enhanced (approximate to 6-fold) by formulation of NIF as nanoparticles. No significant difference was observed either in the presence of chitosan in the formulation or between the three cell models evaluated. To complement these observations, preliminary in vivo pharmacokinetic evaluations in Sprague-Dawley rats, in the fed and fasted states, were also carried out for both un-milled NIF and NIF NP. [less ▲]

Detailed reference viewed: 191 (34 ULg)
Full Text
Peer Reviewed
See detailImmunochemical, biomolecular and biochemical characterization of bovine epithelial intestinal primocultures
Rusu, D.; Loret, S.; Peulen, Olivier ULg et al

in BMC Cell Biology (2005), 6

Background: Cultures of enterocytes and colonocytes represent valuable tools to study growth and differentiation of epithelial cells. In vitro models may be used to evaluate passage or toxicity of drugs ... [more ▼]

Background: Cultures of enterocytes and colonocytes represent valuable tools to study growth and differentiation of epithelial cells. In vitro models may be used to evaluate passage or toxicity of drugs, interactions of enteropathogenes bacteria strains with intestinal epithelium and other physiologic or pathologic phenomenon involving the digestive tract. Results: Cultures of bovine colonocytes and jejunocytes were obtained from organoid-enriched preparations, using a combination of enzymatic and mechanical disruption of the intestine epithelium, followed by an isopicnic centrifugation discarding most single cells. Confluent cell monolayers arising from plated organoids exhibited epithelium typical features, such as the pavement-like structure, the presence of apical microvilli and tight junctions. Accordingly, cells expressed several markers of enterocyte brush border (i.e. maltase, alkaline phosphatase and fatty acid binding protein) as well as an epithelial cytoskeleton component (cytokeratin 18). However, enterocyte primocultures were also positive for the vimentin immunostaining (mesenchyme marker). Vimentin expression studies showed that this gene is constitutively expressed in bovine enterocytes. Comparison of the vimentin expression profile with the pattern of brush border enzymes activities, suggested that the decrease of cell differentiation level observed during the enterocyte isolation procedure and early passages of the primoculture could result from a post-transcriptional de-repression of vimentin synthesis. The low differentiation level of bovine enterocytes in vitro could partly be counteracted adding butyrate (1-2 mM) or using a glucose-deprived culture medium. Conclusion: The present study describes several complementary approaches to characterize bovine primary cultures of intestinal cells. Cultured cells kept their morphologic and functional characteristics during several generations. [less ▲]

Detailed reference viewed: 20 (1 ULg)
Full Text
Peer Reviewed
See detailModulation of intestinal urea cycle by dietary spermine in suckling rat
Gharbi, Myriam ULg; Powroznik, Brigitte; Mazzucchelli, Gabriel ULg et al

in Biochemical and Biophysical Research Communications (2005), 336(4), 1119-1124

Argininosuccinate synthetase, an ubiquitous enzyme in mammals, catalyses the formation of argininosuccinate, the precursor of arginine. Arginine is recognised as an essential amino acid in foetuses and ... [more ▼]

Argininosuccinate synthetase, an ubiquitous enzyme in mammals, catalyses the formation of argininosuccinate, the precursor of arginine. Arginine is recognised as an essential amino acid in foetuses and neonates, but also as a conditionally essential amino acid in adults. Argininosuccinate synthetase is initially expressed in enterocytes during the developmental period, it disappeared from this organ then appeared in the kidneys. Although the importance of both intestinal and renal argininosuccinate synthetases has been recognised for a long time, nutrients have not yet been identified as inducers of the gene expression. In the context of a proteomic screening of intestinal modifications induced by dietary spermine in suckling rats, we showed that argininosuccinate synthetase and carbamoyl phosphate synthase disappeared from enterocytes after this treatment. The disappearance of argininosuccinate synthetase in small intestine was confirmed by immunodetection. Expression of carbamoyl phosphate synthase and argininosuccinate synthetase coding genes decreased also after spermine administration. Expression of other urea cycle enzyme coding genes was modulated by spermine administration: argininosuccinate lyase decreased and arginase increased. Our results fit with the developmental variation of argininosuccinate synthetase and carbamoyl phosphate synthase. Modulation of the gene expression for several urea cycle enzymes suggests a coordination between all the pathway steps and switch toward polyamine (or proline and glutamate) biosynthesis from ornithine. (c) 2005 Elsevier Inc. All rights reserved. [less ▲]

Detailed reference viewed: 73 (10 ULg)