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See detailIn Vitro Stimulation of the Prepubertal Rat Gonadotropin-Releasing Hormone Pulse Generator by Leptin and Neuropeptide Y through Distinct Mechanisms
LEBRETHON, Marie-Christine ULg; Vandersmissen, E.; Gerard, Arlette ULg et al

in Endocrinology (2000), 141(4), 1464-9

Leptin may act as a negative feedback signal to the brain in the control of appetite through suppression of neuropeptide Y (NPY) secretion and stimulation of cocaine- and amphetamine-regulated transcript ... [more ▼]

Leptin may act as a negative feedback signal to the brain in the control of appetite through suppression of neuropeptide Y (NPY) secretion and stimulation of cocaine- and amphetamine-regulated transcript (CART), a new anorectic peptide. We aimed at studying whether leptin, NPY, and CART have related effects on the hypothalamic control of the pituitary-gonadal system and the developmental changes in NPY and CART effects. Using retrochiasmatic hypothalamic explants from prepubertal 15-day-old male rats, the GnRH interpulse interval (mean +/- SD: 62 +/- 5 min) was significantly reduced by 10(-7) M of leptin (46 +/- 3.3 min) as well as 10(-7) M of NPY (47 +/- 4.4 min) and 10(-6) M of CART (46 +/- 2.7 min), whereas the GnRH pulse amplitude was not affected. The stimulatory effects of different NPY receptor agonists [human PYY 3-36, porcine NPY 13-36, human (D-Trp 32) NPY, porcine (Leu 31 Pro 34) NPY, human pancreatic polypeptide (PP)], as well as the absent effects of rat PP were consistent with the involvement of the Y5-receptor subtype in mediation of NPY effects. Incubation with 10(-7) M of a Y5-receptor selective antagonist prevented the effect of NPY (61 +/- 4 vs. 46 +/- 2 min), whereas leptin and CART effects were not (47 +/- 3 vs. 46 +/- 3 min and 46 +/- 3 vs. 46 +/- 2 min, respectively), suggesting that NPY was not involved in leptin and CART effects. Using an anti-CART antiserum (1:1000), the reduction of GnRH interpulse interval caused by leptin was partially prevented (56.2 +/- 4 vs. 47.9 +/- 3.8 min), whereas the reduction of GnRH interval caused by NPY was not affected (45.9 +/-2.5 vs. 47.8 +/- 3.7). The GnRH interpulse interval was decreased by 10(-7) M of NPY at 5 days (72 +/- 3.8 vs. 91.9 +/- 3.5) as well as at 15 days, whereas such an effect was not observed anymore at 25 and 50 days. Similar effects were observed using 10(-6) M of CART-peptide. Using 10(-6) M of the Y5-receptor antagonist, the GnRH interpulse interval was significantly increased at 15 days (66.6 +/- 2.7 min), 25 days (56.5 +/- 39.9 min), and 50 days (52.5 vs. 38.2 min), whereas no change was observed at 5 days. Using the anti-CART antiserum, a significant increase of GnRH interpulse interval was observed at 25 days only. In conclusion, the stimulatory effects of leptin and NPY on the frequency of pulsatile GnRH secretion before puberty involve two distinct mechanisms. NPY causes acceleration of GnRH pulsatility via the Y5-receptor subtype, which is not involved in leptin effects while the CART is involved in leptin effects on GnRH secretion but not in NPY effects. The reduction of pulsatility by the Y5 antagonist provides evidence of endogenous NPY involvement in the control of GnRH secretion from the time of onset of puberty. [less ▲]

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See detailIn vitro studies on the Fc-receptor function of mononuclear phagocytes in rheumatoid arthritis: relation between the Fc-receptor blockade and the concanavalin A-binding capacity of autologous immunoglobulin G
Malaise, Michel ULg; Franchimont, P.; Houssier, C. et al

in Journal of Clinical Immunology (1986), 6(6), 442-456

The Fc-receptor (Fc-R) function of monocytes isolated from 19 control subjects and from 30 patients presenting with a rheumatoid arthritis (RA) was assessed in vitro by a classical rosette assay using IgG ... [more ▼]

The Fc-receptor (Fc-R) function of monocytes isolated from 19 control subjects and from 30 patients presenting with a rheumatoid arthritis (RA) was assessed in vitro by a classical rosette assay using IgG-coated sheep red blood cells. In RA patients, the percentage of monocytes forming rosettes was significantly lower than in controls (34.4 +/- 20.4 versus 67.4 +/- 4.5%; P less than 0.001). The blockade observed was reversed by a prior trypsin treatment of RA monocytes, the percentage of recovery being correlated with the IgG plasma levels. Besides, IgG purified from the serum of four RA patients bound a mean of 7.3, 5.2, 1.6, and 1.6 times more than normal IgG did onto concanavalin A (Con A), peanut agglutinin (PNA), phytohemagglutinin (PHA), and pokeweed mitogen (PWM), respectively. Although similar amounts of 125I-labeled normal and RA IgG were bound to normal monocytes, RA IgG inhibited more efficiently than normal IgG the Fc-R function of normal monocytes, for all concentrations tested (10 to 100 micrograms/100 microliters). A prior treatment of RA IgG by alpha-mannosidase, but not by beta-galactosidase, significantly reduced their inhibitory properties. The incubation of monocytes with D-mannose or mannan reduced their capacity to form rosettes. The percentage of monocytes forming rosettes in the presence of both mannan and normal IgG was significantly lower than that measured in the presence of normal IgG only. On the contrary, the rosetting capacity of monocytes in the presence of both RA IgG and mannan was the same as that calculated in the presence of RA IgG only. The inhibitory effect of RA IgG was not related to their abnormal circular dichroism. Our data suggest that the greater ability of RA IgG to block the Fc-R function of monocytes probably depends on the presence of a greater number of accessible mannosyl residues on the glycosidic side chains located in the Fc domain of the molecules. [less ▲]

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See detailIN VITRO STUDY OF A FIBER NETWORK TAILORED AS 3D-CELL MODEL
Sevrin, Chantal ULg; Lombart, François ULg; Godino, Miguel et al

Poster (2014, June 17)

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See detailIn vitro study of coinfection/superinfection parameters which can influence recombination events in noroviruses
Di Felice, Elisabetta; Ceci, Chiara; Toffoli, Barbara et al

Poster (2014, October 17)

Noroviruses (NoVs) are non-enveloped, single-stranded, positive-sense RNA viruses. They are important causes of acute non-bacterial gastroenteritis in humans worldwide but their study is currently yet ... [more ▼]

Noroviruses (NoVs) are non-enveloped, single-stranded, positive-sense RNA viruses. They are important causes of acute non-bacterial gastroenteritis in humans worldwide but their study is currently yet hampered by the lack of a cell culture system. NoVs genetically evolve by both point mutations and recombination and the murine norovirus (MuNoV) is considered as the best model for human NoVs. The aim of this study was to develop an experimental model based on the MuNoV in order to investigate coinfection/superinfection parameters that could impact recombination events. Monolayers of RAW264.7 cells were coinfected or superinfected with two MuNoV strains (CW1 and WU20) using different multiplicity of infection (0.1/1; 1/1 and 10/1 for CW1 and Wu20 , respectively) and time delays (0h; 0.5h; 1h; 2h; 4h; 8h; 12h and 24h) for infection. Supernatants were collected at 24 and 48 hours post-infection. Genomic copies of both viruses were first quantified by RT-QPCR. Then, viruses from the supernatants were plaque purified (36 clones per condition) and their recombinant status was checked by a real-time PCR discriminating method using primers targeting both extremity of the MuNoV genome. Results of quantitative and plaque picking assays are compared. Together, the results confirm that recombination does not frequently occur, at least in vitro and raise the issue on why these events are however so usual with in silico detection methods. The data also showed that superinfection exclusion seems to be triggered from 4h post infection with the first MuNoV. The mechanisms of the later should be still studied. [less ▲]

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See detailIn vitro study of fibroblasts (L929) and osteoblasts (MG-63) within networks differing in fiber density.
Lombart, François ULg; Alexandre, Diane ULg; de Bien, Charlotte ULg et al

Poster (2013, June 18)

Animal cells are typically cultivated in vitro on 2D surfaces therefore in conditions totally differing from their 3D in vivo environments. It is therefore really attractive to generate better in vitro ... [more ▼]

Animal cells are typically cultivated in vitro on 2D surfaces therefore in conditions totally differing from their 3D in vivo environments. It is therefore really attractive to generate better in vitro animal cell models where animal cells can adhere and proliferate within a 3D networks. When facing to a third dimension, the design of the scaffolds tailored to support the organization and communication of cells should favor at least cell adhesion, proliferation and differentiation, while promoting nutrient, gas (O2 / CO2) and waste product diffusion. In order to construct this in vitro model, we have compared the cell reactivity of two model cell lines fibroblaste L 929 and osteoblaste MG-63 within three 3D networks differing in fiber density. This parameter has been altered in order to increase progressively the total surface exposed to the cells, whilst increasing correspondingly the mean pore size and total porosity of the network, whilst keeping the same architecture and surface chemistry of the fibers within the scaffold. [less ▲]

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See detailIn Vitro Study of the Antioxidant Properties of Nimesulide and 4-Oh Nimesulide: Effects on Hrp- and Luminol-Dependent Chemiluminescence Produced by Human Chondrocytes
Zheng, S. X.; Mouithys-Mickalad, Ange ULg; Deby-Dupont, G. P. et al

in Osteoarthritis and Cartilage (2000), 8(6), 419-25

OBJECTIVES: Reactive oxygen species (ROS) are now recognized to play an important role in the pathogenesis of rheumatic diseases and constitute an interesting therapeutic target for drugs. This in vitro ... [more ▼]

OBJECTIVES: Reactive oxygen species (ROS) are now recognized to play an important role in the pathogenesis of rheumatic diseases and constitute an interesting therapeutic target for drugs. This in vitro study was designed to evaluate the antioxidant properties of nimesulide (NIM), a nonsteroidal antiinflammatory drug of the sulfonanilide class, and its main metabolite 4-OH nimesulide (4-OHNIM). METHODS: The scavenging effects of NIM and 4-OH NIM on hydroxyl radical ((.)OH) and superoxide anions (O(minusd)(2)) were investigated by electron spin resonance (ESR), using 5, 5-dimethylpyrroline-N-oxide (DMPO) as the spin trap agent. The quenching properties of these drugs on hypochlorite anion was studied by luminol enhanced chemiluminescence. Finally, the effects of NIM and 4-OHNIM on the reactive oxygen species production by human articular chondrocytes were recorded by HRP and luminol-enhanced chemiluminescence. RESULTS: By this method it has been demonstrated that NIM and 4-OHNIM, at concentrations ranging from 10 to 100 microM, are potent scavengers of(.)OH whereas only 4-OHNIM was capable to scavenge O(minusd)(2). Chemiluminescence generated by HOCl was also significantly and dose-dependently inhibited by both NIM and 4-OHNIM. Nevertheless, at each concentration tested, the inhibitory effect of 4-OHNIM was significantly more marked, even at the highest concentration (100 microM). Furthermore, when chondrocytes were pre-incubated for 48-96 h with NIM or 4-OHNIM, the luminol- and HRP-dependent CL produced by the cells was significantly inhibited in a dose-dependent manner. CONCLUSIONS: NIM and 4-OHNIM may protect cartilage against oxidative stress, not only by scavenging ROS but also by inhibiting their production by chondrocytes. [less ▲]

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See detailIn vitro study of the antioxidant properties of non steroidal anti-inflammatory drugs by chemiluminescence and electron spin resonance (ESR).
Mouithys-Mickalad, Ange ULg; Zheng, S. X.; Deby-Dupont, G. P. et al

in Free Radical Research (2000), 33(5), 607-21

OBJECTIVES: To determine the antioxidant activities of nonsteroidal anti-inflammatory drugs (NSAIDS), we examined by chemiluminescence (CL) and electron spin resonance (ESR) their scavenging properties ... [more ▼]

OBJECTIVES: To determine the antioxidant activities of nonsteroidal anti-inflammatory drugs (NSAIDS), we examined by chemiluminescence (CL) and electron spin resonance (ESR) their scavenging properties towards lipid peroxides, hypochlorous acid and peroxynitrite. METHODS: The antioxidant properties of nimesulide (NIM), 4-hydroxynimesulide (4-HONIM), aceclofenac (ACLO), 4-hydroxyaceclofenac (4-HOA-CLO), diclofenac (DICLO) and indomethacin (INDO) were tested on four different reactive oxygen species (ROS) generating systems: (I) phorbol-myristate acetate (PMA)-activated neutrophils, (II) Fe2+/ascorbate-induced lipid peroxidation, (III) HOCl-induced light emission, (IV) the kinetics of ONOO- decomposition followed by spectrophotometry. ROS production was monitored by luminol-enhanced CL or by ESR using two different spin traps. RESULTS: At 10 microM, ACLO, NIM, 4-HONIM, 4-HOA-CLO, and DICLO decreased luminol-enhanced CL generated by PMA-activated neutrophils. Inversely, INDO increased the luminol enhanced CL. Interestingly, hydroxylated metabolites were more potent antioxidants than the parent drugs. Furthermore, all drugs tested, excepted ACLO, lowered lipid peroxidation induced by Fe2+/ascorbate system. ACLO and DICLO, even at the highest concentration tested (100 microM), did not significantly lower HOCl induced CL, whereas the other drugs were potent scavengers. Finally, all the NSAIDS accelerated decomposition of ONOO-, suggesting a potential capacity of the molecules to scavenge peroxynitrite. CONCLUSION: The NSAIDs possess variable degrees of antioxidant activities, linked to their ability to react with HOCl, lipid peroxides or ONOO-. These antioxidant activities could offer interesting targeted side-effects in the treatment of joint inflammatory diseases. [less ▲]

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See detailIn vitro study of the influence of temperature, pH and Aw on the growth rate of trichoderma aspergillum
Begoude, B. A. D.; Lahlali, R.; Friel, D. et al

in Bulletin OILB/SROP = IOBC/WPRS Bulletin (2007), 30

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See detailIn vitro study of the interactions between bovine herpesvirus 4 and the bovine host cells
Vanderplasschen, Alain ULg

in Bulletin et Mémoires de l'Académie Royale de Médecine de Belgique (1999), 154

This work was devoted to the study of the interactions between bovine herpesvirus 4 (BHV-4) and bovine cells in vitro. It led to the discovery of two interesting properties of BVH-4 replication cycle ... [more ▼]

This work was devoted to the study of the interactions between bovine herpesvirus 4 (BHV-4) and bovine cells in vitro. It led to the discovery of two interesting properties of BVH-4 replication cycle: first, the cellular receptor heparan sulfate was proven to mediate BVH-4 binding to target cells. This is the first description of the implication of heparan sulfate in the binding process of a gammaherpesvirus. Second, using synchronised cells, the replication of BVH-4 DNA was proven to be dependent on the S phase of the cell cycle. This dependence could explain some properties of BVH-4 infection in vitro and could play an important role in the biology of the infection in vivo. Finally, in order to produce monoclonal antibodies against BVH-4 IE1 and IE2 proteins, the genes coding for these proteins were cloned and expressed in prokaryotic cells. [less ▲]

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See detailIn vitro study of the specific interaction between poly (2-dimethylamino ethylmethacrylate) based polymers with platelets and red blood cells.
Flebus, Luca ULg; Lombart, François ULg; Martinez-Jothar, L et al

in International Journal of Pharmaceutics (2015), 492

Poly(2-dimethylamino)ethyl methacrylate (PDMAEMA) is an attractive polycation frequently proposed as a non-viral vector for gene therapy. As expected for other cationic carriers, intravenous ... [more ▼]

Poly(2-dimethylamino)ethyl methacrylate (PDMAEMA) is an attractive polycation frequently proposed as a non-viral vector for gene therapy. As expected for other cationic carriers, intravenous administration of PDMAEMA can result in its ionic complexation with various negatively charged domains found within the blood. To gain more insight into this polycation hemoreactivity, we followed the binding kinetics of a free form (FF) of fluorescein labelled PDMAEMA (below 15 kDa) in normal human blood using flow cytometry. This in vitro study highlighted that platelets display higher affinity for this polycation compared to red blood cells (RBCs), with an adsorption isotherm characteristics of a specific saturable binding site. PDMAEMA (1-20μg/mL) exerted a concentration dependent proaggregant effect with a biphasic aggregation of washed platelets. Activation of platelets was also noticed in whole blood with the expression of P-selectin and fibrinogen on platelet surface. Although additional studies would be needed in order to elucidate the mechanism of PDMAEMA mediated activation of platelets, our manuscript provides important information on the hemoreactivity of FF PDMAEMA. [less ▲]

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See detailIn vitro study on the effects of aceclofenac on proteoglycan and type II collagen production by human chondrocytes
Henrotin, Yves ULg; Labasse, A; Degroote, D et al

in Osteoarthritis and Cartilage (1997), 5

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See detailIn vitro study toward the endocrine activity and the genotoxic potential of migration products from plastic baby bottles
Simon, Coraline ULg; Onghena, M.; Covaci, A. et al

Poster (2014, November 20)

Bisphenol A (BPA) is used since 1960 as a primary raw material for the production of polycarbonate (PC) plastic and epoxy resin, widely used in a variety of common products including digital media (e.g ... [more ▼]

Bisphenol A (BPA) is used since 1960 as a primary raw material for the production of polycarbonate (PC) plastic and epoxy resin, widely used in a variety of common products including digital media (e.g., CDs, DVDs), electrical and electronic equipment, automobiles, sports safety equipment, reusable food and drink containers , as well as baby bottle. During the last decades, in several studies, the migration of BPA is documented to be a well-known source of food contamination. Some studies have shown that BPA, which is able to mimic the action of and hormone and to disrupt normal endocrine function, may be associated to several health problems and diseases. Recently, the European Union took a series of measures, including a ban for the import and sale PC baby bottles to reduce BPA exposure to infants. Plastic alternatives to polycarbonate have massively appeared on Belgium market. Although there are several studies on BPA migration from polycarbonate into foodstuff under a variety of conditions, there is a small amount of information about consequences on human health of the potential exposure to chemicals migrating from PC alternatives, including bottles commonly labelled “free BPA”. In a recent opinion (No. 8697, 11.03.2010), the Belgium Superior Health Council's issued its concern regarding the currently used alternatives to PC. Furthermore, they asked to investigate the possible risks associated with the use of these alternatives. In order to evaluate the safety of these alternatives, the genotoxicity and the activity on several receptors of chemical compounds migrating from PC alternatives, identified by Simoneau & al, 2012 , were evaluated using reporter gene assays. Receptor agonistic and antagonistic activities of 39 pure compounds were measured. After the first screening, certain substances clearly showed an activity on several receptors such as BPA, and Bisphenol S, while only a few substances showed no reaction on the different receptor. None of the 39 components was genotoxic as identified in the Vitotox test. However, further experiments will be performed to characterize their activity and confirm the result for the genotoxicity. [less ▲]

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See detailIn vitro study toward the endocrine activity and the genotoxic potential of migration products from plastic baby bottles
Simon, Coraline ULg; Onghena, M.; Covaci, A. et al

in Organohalogen Compounds (2014), 76

Bisphenol A (BPA) is documented in several studies to be a well-known source of food contamination. Recently, the European Union took a series of measures, including a ban for the import and sale of ... [more ▼]

Bisphenol A (BPA) is documented in several studies to be a well-known source of food contamination. Recently, the European Union took a series of measures, including a ban for the import and sale of polycarbonate (PC) baby bottles to reduce BPA exposure of infants. Plastic alternatives to PC, which have massively appeared on the Belgian market, include polypropylene (PP), silicone, polyamide (PA) and polyethersulfone (PES). In a recent opinion (No. 8697, 11.03.2010), the Belgian Superior Health Council issued its concern regarding the alternatives to PC currently used. Furthermore, they asked to investigate the possible risks associated with the use of these alternatives. In this study, a screening towards the endocrine activity of chemicals migrating from PC alternatives, identified by the group of Simoneau, was performed by using different reporter gene assays. Furthermore, the genotoxic potential of these compounds was also assessed with the Vitotox assay, an indicator test for DNA damage. The aim of the screening was to select the substances that may present a risk for human health and thus require further characterization. [less ▲]

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See detailIn vitro survival of vitrified goat embryos: comparison of two vitrification methods
Guignot, F.; Baril, G.; Pougnard, J. L. et al

in Proceedings: 17e Réunion A.E.T.E. (2001)

Detailed reference viewed: 12 (1 ULg)