References of "Moonen, Gustave"
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See detailIdentification of factors that maintain mammalian outer hair cells in adult organ of Corti explants
Malgrange, Brigitte ULg; Rigo, Jean-Michel; Coucke, Paul et al

in Hearing Research (2002), 170(1-2), 48-58

Both outer hair cells (OHCs) and inner hair cells (IHCs) survive and mature in 3 days old rat organ of Corti explants cultured for I month in a minimal essential medium. In contrast. under the same ... [more ▼]

Both outer hair cells (OHCs) and inner hair cells (IHCs) survive and mature in 3 days old rat organ of Corti explants cultured for I month in a minimal essential medium. In contrast. under the same culture conditions, only IHCs survive in explants from adult guinea pig organ of Corti while many of the OHCs are lost within the first 48 It. Hair cell Count,, show OHCs loss to be greater in the lower portion (i.e. middle turn) of the cochlea than Lit the apex. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) indicates that there is DNA damage in adult OHCs, within 8 h of explantation. Treatment of the adult organ of Corti explants with either actinomycin D (10(-7) M) or cycloheximide (10(-6) M) prevents most OHC losses . According to these results apoptosis may be the mechanism of OHC loss in adult organ of Corti explants, Stable membrane potentials recorded from the OHCs in both uncultured and actinomycin D-treated organ of Corti explants cultured for 72 h demonstrate the functional integrity of these hair cells. OHC losses in the adult guinea pig, organ of Corti cultures can also be prevented by treatment with several of the growth factors tested. i.e. acidic fibroblast growth factor (aFGF), insulin-like growth factor-1 (IGF-1), epidermal growth factor (EGF), transforming growth factor-beta1 (TGF-beta1). and glial cell-derived neurotrophic factor (GDNF). The results of this study suggest that growth factor therapy may be applicable to the treatment of some hearing disorders. (C) 2002 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailThe anti-epileptic drug levetiracetam reverses the inhibition by negative allosteric modulators of neuronal GABA- and glycine-gated currents
Rigo, Jean-Michel; Hans, Grégory ULg; Nguyen, Laurent ULg et al

in British Journal of Pharmacology (2002), 136(5), 659-672

1 In this study in vitro and in vivo approaches were combined in order to investigate if the anti-epileptic mechanism(s) of action of levetiracetam (LEV; Keppra(R)) may involve modulation of inhibitory ... [more ▼]

1 In this study in vitro and in vivo approaches were combined in order to investigate if the anti-epileptic mechanism(s) of action of levetiracetam (LEV; Keppra(R)) may involve modulation of inhibitory neurotransmission. 2 GABA- and glycine-gated currents were studied in vitro using whole-cell patch-clamp techniques applied on cultured cerebellar granule, hippocampal and spinal neurons. Protection against clonic convulsions was assessed in vivo in sound-susceptible mice. The effect of LEV was compared with reference anti-epileptic drugs (AEDs): carbamazepine, phenytoin, valproate, clonazepam, phenobarbital and ethosuximide. 3 LEV contrasted the reference AEDs by an absence of any direct effect on glycine-gated currents. At high concentrations, beyond therapeutic relevance, it induced a small reduction in the peak amplitude and a prolongation of the decay phase of GABA-gated currents. A similar action on GABA-elicited currents was observed with the reference AEDs, except ethosuximide. 4 These minor direct effects contrasted with a potent ability of LEV (EC50 = 1-10 muM) to reverse the inhibitory effects of the negative allosteric modulators zinc and beta-carbolines on both GABA(A) and glycine receptor-mediated responses. 5 Clonazepam, phenobarbital and valproate showed a similar ability to reverse the inhibition of beta-carbolines on GABA-gated currents. Blockade of zinc inhibition of GABA responses was observed with clonazepam and ethosuximide. Phenytoin was the only AED together with LEV that inhibited the antagonism of zinc on glycine-gated currents and only clonazepam and phenobarbital inhibited the action of DMCM. 6 LEV (17 mg kg(-1)) produced a potent suppression of sound-induced clonic convulsions in mice. This protective effect was significantly abolished by co-administration of the beta-carboline FG 7142, from a dose of 5 mg kg(-1). In contrast, the benzodiazepine receptor antagonist flumazenil (up to 10 mg kg(-1)) was without any effect on the protection afforded by LEV. 7 The results of the present study suggest that a novel ability to oppose the action of negative modulators on the two main inhibitory ionotropic receptors may be of relevance for the anti-epileptic mechanism(s) of action of LEV. [less ▲]

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See detailNestin expression in cultivated mesenchymal stem cells: Regulation and potential role in their neural differentiation
Wislet-Gendebien, Sabine ULg; Leprince, Pierre ULg; Moonen, Gustave ULg et al

in Glia (2002, May), (Suppl. 1), 87

Bone marrow stromal cells can differentiate into many types of mesenchymal cells, i.e. osteocyte, chondrocyte, fibroblast and adipocyte, but can also differentiate into non-mesenchymal cell, i.e. neural ... [more ▼]

Bone marrow stromal cells can differentiate into many types of mesenchymal cells, i.e. osteocyte, chondrocyte, fibroblast and adipocyte, but can also differentiate into non-mesenchymal cell, i.e. neural cells in appropriate in vivo experimental conditions (Kopen and al.,PNAS,96, 10711,1999, Brazelton and al, Science, 290,1175, 2000, Mezey and al, Science, 290,1179, 2000). In neurological disorders, such as Alzheimer's and Parkinson's diseases, auto-transplantation of neural cell types derived from mesenchymal stem cells offers the potential of replacing lost cells and recovering lost functions. Nestin is an intermediate filament protein predominantly expressed by neural stem cells and is used to identify neural progenitor. In this study, we demonstrate that cultured rat mesenchymal stem cells (rMSC) can express nestin in appropriate conditions. Two factors contribute to the regulation of nestin expression by rMSC : 1) the presence of serum-derived components in the culture medium which repress nestin expression and 2) the cell’s number of passages. LPA and thrombin mimic this serum effect. Furthermore, when nestin- positive cells are trypsinized and resuspended into culture conditions used for neural stem cells (NSC), sphere formation is observed. Likewise, by co-cultivating nestin-positive rMSC with NSC derived from green mouse, heterogenous spheres were obtained. When those heterogenous spheres are placed on polyornithine-coated surfaces, a differentiation of some rMSC into GFAP-positive cells occurs. These results indicate that nestin expression might be a pre-requisite for the acquisition by rMSC of the capacity to differentiate into some neural cell types. [less ▲]

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See detailFunctional glycine receptors are expressed by postnatal nestin-positive neural stem/progenitor cells
Nguyen, Laurent ULg; Malgrange, Brigitte ULg; Belachew, Shibeshih ULg et al

in European Journal of Neuroscience (2002), 15(8), 1299-1305

Multipotent neural stem and progenitor cells (NS/PCs) are well-established cell subpopulations occurring in the developing, and also in the mature mammalian nervous systems. Trophic and transcription ... [more ▼]

Multipotent neural stem and progenitor cells (NS/PCs) are well-established cell subpopulations occurring in the developing, and also in the mature mammalian nervous systems. Trophic and transcription factors are currently the main signals known to influence the development and the commitment of NS/PCs and their progeny. However, recent studies suggest that neurotransmitters could also contribute to neural development. In that respect, rodent-cultured embryonic NS/PCs have been reported to express functional neurotransmitter receptors. No similar investigation has, however, been made in postnatal and/or in adult rodent brain stem cells. In this study, using RT-PCR and immunocytochemical methods, we show that alpha(1) -, alpha(2) - and beta-subunit mRNAs and alpha-subunit proteins of the glycine ionotropic receptor are expressed by 80.5 +/- 0.9% of postnatal rat striatum-derived, nestin-positive cells within cultured neurospheres. Whole-cell patch-clamp experiments further demonstrated that glycine triggers in 33.5% of these cells currents that can be reversibly blocked by strychnine and picrotoxin. This demonstrates that NS/PCs express functional glycine receptors, the consequence(s) of their activation remaining unknown. [less ▲]

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See detailProliferative generation of mammalian auditory hair cells in culture
Malgrange, Brigitte ULg; Belachew, Shibeshih ULg; Thiry, Marc ULg et al

in Mechanisms of Development (2002), 112(1-2), 79-88

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See detailModulation of neuronal survival and excitability by an astroglia-derived factor.
HANS, Grégory ULg; Moonen, Gustave ULg; Rigo, Jean-Michel

in Journal of physiology, Paris (2002), 96(3-4), 323-8

We summarize here currently available data related to an astroglia-secreted factor that induces neuronal apoptosis and behaves as an inhibitor of ionotropic inhibitory GABA(A) and glycine receptors.

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See detailProliferation generation of auditory hair cells in culture
Malgrange, B; Belachew, S; Thiry, Marc ULg et al

in Acta Oto-Rhino-Laryngologica Belgica (2002), 56

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See detailPharmacologic treatment of inner ear: from basic science to the patient.
Lefèbvre, Philippe ULg; Staecker, H.; Van de Water, T. et al

in Acta Oto-Rhino-Laryngologica Belgica (2002), 56(1), 45-9

Most of the deafness are of sensorineural origin and are characterized by a loss of hair cells and of spiral ganglion neurons. At the present time, hearing aids are the only treatment. However, in some ... [more ▼]

Most of the deafness are of sensorineural origin and are characterized by a loss of hair cells and of spiral ganglion neurons. At the present time, hearing aids are the only treatment. However, in some diseases of the inner ear, pharmacological treatment have been proposed and used successfully. In this paper, we will review some basic science aspects of the biology of the neurosensory structures of the inner ear, in particular of the auditory neurons, that lead to the rationale of some treatments for the inner ear diseases. Developmental studies, neuronal cell culture experiments, and analyses of gene knockout animals reveal a number of growth factors which are important for the rescue and repair of injured auditory neurons in the inner ear. These factors rescue the injured auditory neurons in vivo. Furthermore, perfusion of antioxydant to the cochlea prevented the hearing loss induced by cisplatin. These in vitro and in vivo experiments demonstrate that it is possible to manipulate the neurosensory structures of the inner ear and provide an effective treatment to prevent the degeneration of the neurons. The molecules or drugs can be administered locally to the inner ear through a direct perilymphatic perfusion or through the round window membrane. As an example, we will discuss the treatment of patients suffering from idiopathic sensorineural hearing loss which can be treated successfully by a perfusion through the round window membrane, improving their hearing threshold and their speech discrimination. [less ▲]

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See detailMechanisms of cell death in the injured auditory system: Otoprotective strategies
Lefèbvre, Philippe ULg; Malgrange, Brigitte ULg; Lallemend, François et al

in Audiology & Neuro-otology (2002), 7(3, May-Jun), 165-170

Oxidative stress insults such as neurotrophin withdrawal, sound trauma, hypoxia/ischemia, ototoxic antibiotics, and chemotherapeutic agents have been shown to induce apoptosis of both auditory hair cells ... [more ▼]

Oxidative stress insults such as neurotrophin withdrawal, sound trauma, hypoxia/ischemia, ototoxic antibiotics, and chemotherapeutic agents have been shown to induce apoptosis of both auditory hair cells and neurons. In this paper, we review some components of the apoptotic pathways leading to the death of hair cells and auditory induced by growth factor withdrawal or cisplatin intoxication: (1) reactive oxygen species and free radicals are formed as by-products of several metabolic pathways and these molecules can themselves cause cell damage by reacting with cellular proteins; (2) activation of caspases, and (3) activation of calpain. These mechanisms have several different points at which inhibitors could be targeted to protect cells from programmed cell death, including the prevention of oxidative stress-induced apoptosis and the activation of caspases and calpains. Copyright (C) 2002 S. Karger AG, Basel. [less ▲]

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See detailEffects of incidental and intentional feature binding on recognition: a behavioural and PET activation study
Lekeu, Françoise ULg; Van der Linden, Martial ULg; Collette, Fabienne ULg et al

in Neuropsychologia (2002), 40(2), 131-144

Using Positron Emission Tomography (PET), we investigated cerebral regions associated with the episodic recognition of words alone and words bound to contextual colours. Two modes of colour encoding were ... [more ▼]

Using Positron Emission Tomography (PET), we investigated cerebral regions associated with the episodic recognition of words alone and words bound to contextual colours. Two modes of colour encoding were tested: incidental and intentional word-to-colour binding. Word-only recognition was associated with brain activation in a lexico-semantic left middle temporal region and in the cerebellum following an incidental colour encoding, and with brain activation in the left posterior middle frontal gyrus, right anterior cingulate and right inferior frontal gyrus following an intentional encoding. Recognition of bound features was associated with activation in left prefrontal and superior parietal regions following an incidental colour encoding, and with preferential right prefrontal cortex activation following an intentional colour encoding. Our results are in line with the hypothesis of a parietal involvement in context processing, and prefrontal areas in monitoring retrieval processes. Our results also support the hypothesis of a 'cortical asymmetry for reflective activity' (CARA). [less ▲]

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See detailNeural and cognitive bases of upper limb apraxia in corticobasal degeneration
Peigneux, Philippe ULg; Salmon, Eric ULg; Garraux, Gaëtan ULg et al

in Neurology (2001), 57(7), 1259-1268

OBJECTIVE: To investigate the neural and cognitive bases of upper limb apraxia in corticobasal degeneration (CBD). METHODS: Eighteen patients with CBD underwent a cognitive neuropsychological assessment ... [more ▼]

OBJECTIVE: To investigate the neural and cognitive bases of upper limb apraxia in corticobasal degeneration (CBD). METHODS: Eighteen patients with CBD underwent a cognitive neuropsychological assessment of apraxia and resting [(18)F]-fluorodeoxyglucose PET scanning. Two complementary measures of apraxia were computed for each modality of gesture production. First, a performance score measured error frequency during gesture execution. Second, as a more stringent test of the integrity of the praxis system, the correction score measured the patient's ability to correct his or her errors on a second attempt. For each measure type, a cut-off score for the presence of apraxia was defined with regard to healthy controls. Using each cut-off score, the regional cerebral glucose metabolism of patients with CBD with apraxia (i.e., performing below cut-off score) was compared with that of patients with CBD without apraxia. RESULTS: Mean performance scores were below normal values in all modalities. Anterior cingulate hypometabolism predominated in patients with CBD who performed below the cut-off performance score. At variance, mean correction scores were below normal values for gesture imitation only. Hypometabolism in superior parietal lobule and supplementary motor area characterized patients with CBD who were unable to correct their errors at the same rate as control subjects did. CONCLUSIONS: Distinct neural networks underlie distinct aspects of the upper limb apraxic deficits in CBD. Extending previous findings of gesture production deficits in CBD, the use of complementary measures of apraxic behavior discloses a visuoimitative upper limb apraxia in CBD, underlain by a metabolic decrease in a parietofrontal neural network. [less ▲]

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See detailNeurotransmitters as Early Signals for Central Nervous System Development
Nguyen, Laurent ULg; Rigo, Jean-Michel; Rocher, Véronique et al

in Cell & Tissue Research (2001), 305(2), 187-202

During brain ontogenesis, the temporal and spatial generation of the different types of neuronal and glial cells from precursors occurs as a sequence of successive progenitor stages whose proliferation ... [more ▼]

During brain ontogenesis, the temporal and spatial generation of the different types of neuronal and glial cells from precursors occurs as a sequence of successive progenitor stages whose proliferation, survival and cell-fate choice are controlled by environmental and cellular regulatory molecules. Neurotransmitters belong to the chemical microenvironment of neural cells, even at the earliest stages of brain development. It is now established that specific neurotransmitter receptors are present on progenitor cells of the developing central nervous system and could play, during neural development, a role that has remained unsuspected until recently. The present review focuses on the occurrence of neurotransmitters and their corresponding ligand-gated ion channel receptors in immature cells, including neural stem cells of specific embryonic and neonatal brain regions. We summarize in vitro and in vivo data arguing that neurotransmitters could regulate morphogenetic events such as proliferation, growth, migration, differentiation and survival of neural precursor cells. The understanding of neurotransmitter function during early neural maturation could lead to the development of pharmacological tools aimed at improving adult brain repair strategies. [less ▲]

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See detailLe cas clinique du mois. A propos d'un cas de syndrome des antiphospholipides
Fumal, Arnaud ULg; Belachew, Shibeshih ULg; Moonen, Gustave ULg et al

in Revue Médicale de Liège (2001), 56(7), 480-3

This article reports a case of Anton-Babinski syndrome, due to right middle cerebral artery thrombosis and attributed to a likely primary antiphospholipid syndrome. It is always difficult to diagnose the ... [more ▼]

This article reports a case of Anton-Babinski syndrome, due to right middle cerebral artery thrombosis and attributed to a likely primary antiphospholipid syndrome. It is always difficult to diagnose the latter, especially in the case of our patient who had a past history of multiple venous thromboses but also a heterozygosity for the mutation of the factor V of Leyden. We reviewed the literature dedicated to the prothrombotic events linked to the presence of these antiphospholipid antibodies: the lupus anticoagulant and the anticardiolipin antibodies. [less ▲]

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See detailPoly(D,L-lactide) foams modified by poly(ethylene oxide)-block-poly(D,L-lactide) copolymers and a-FGF: in vitro and in vivo evaluation for spinal cord regeneration
Maquet, Véronique; Martin, Didier ULg; Scholtes, Félix ULg et al

in Biomaterials (2001), 22(10), 1137-1146

The first goal of this study was to examine the influence that poly(ethylene oxide)-block-poly(D,L-lactide) (PELA) copolymer can have on the wettability, the in vitro controlled delivery capability, and ... [more ▼]

The first goal of this study was to examine the influence that poly(ethylene oxide)-block-poly(D,L-lactide) (PELA) copolymer can have on the wettability, the in vitro controlled delivery capability, and the degradation of poly(D,L-lactide) (PDLLA) foams. These foams were prepared by freeze-drying and contain micropores (10 μm) in addition of macropores (100 μm) organized longitudinally. Weight loss, water absorption, changes in molecular weight, polymolecularity (Mw/Mn) and glass transition temperature ( Tg) of PDLLA foams mixed with various amounts of PELA were followed with time. It was found that 10 wt% of PELA increased the wettability and the degradation rate of the polymer foams. The release of sulforhodamine (SR) was compared for PDLLA and PDLLA-PELA foams in relation with the foam porosity. An initial burst release was observed only in the case of the 90:10 PDLLA/PELA foam. The ability of the foam of this composition to be integrated and to promote tissue repair and axonal regeneration in the transected rat spinal cord was investigated. After implantation of ca. 20 polymer rods assembled with fibrin-glue, the polymer construct was able to bridge the cord stumps by forming a permissive support for cellular migration, angiogenesis and axonal regrowth. [less ▲]

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See detailL'image du mois. Une thrombose veineuse cerebrale
Garraux, Gaëtan ULg; Sadzot, Bernard ULg; Flandroy, Pierre et al

in Revue Médicale de Liège (2001), 56(2), 61-2

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See detailSupernumerary outer hair cells arise external to the last row of sensory cells in the organ of corti.
Lefèbvre, Philippe ULg; Malgrange, Brigitte ULg; Thiry, Marc ULg et al

in Acta Oto-Laryngologica (2001), 121(2), 164-8

During the development of the mammalian inner ear, the number of hair cells produced is highly regulated and remains constant throughout life. The mechanism underlying this regulation is beginning to be ... [more ▼]

During the development of the mammalian inner ear, the number of hair cells produced is highly regulated and remains constant throughout life. The mechanism underlying this regulation is beginning to be understood although many aspects still remain obscure. When late embryonic or early postnatal rat organs of Corti were cultured, the production of supernumerary hair cells was observed. This overproduction of sensory cells could be modulated by the addition of several growth factors. In this study, we examined explants of rat organs of Corti that produced supernumerary hair cells. In the supernumerary hair cell region, up to two rows of inner hair cells and five rows of outer hair cells were observed. Morphological evaluation of these specimens revealed that less mature hair cells were located in the most external rows of these sensory cells. When a supernumerary hair cell was produced, a supporting cell (i.e. Deiters' cell) was also produced, strongly suggesting that the conversion of a Deiters' cell into a hair cell was not the mechanism that produced these extra hair cells. Based on these results, we propose that prosensory cells located at the external edge of the organ of Corti retain a capacity to form hair cells and that it is these prosensory cells that differentiate into supernumerary hair cells and Deiters' cells. [less ▲]

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See detailHensen's cells acquire specific hair cell markers in vitro, strengthening their role as precursors of supernumerary OHCs
Lefèbvre, P; Malgrange, B; Thiry, Marc ULg et al

Conference (2001)

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See detailHensen's cells as precursors of supernumerary OHCs
Malgrange, B; Lefèbvre, P; Thiry, Marc ULg et al

Poster (2001)

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See detailPhenotypic plasticity of cerebellar radial glia
Leprince, P; Chanas-Sacré, G; Nguyen, L et al

Poster (2001)

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