Astroglia-released factor with negative allosteric modulatory properties at the GABA A receptor.
; Belachew, Shibeshih ; et al
in Biochemical Pharmacology (1996), 52(3), 465-473
We have previously shown, using whole-cell patch-clamp techniques, that astrocytes release a negative allosteric modulator of the gamma-aminobutyric acid type A receptor (GABAA receptor) with beta ... [more ▼]
We have previously shown, using whole-cell patch-clamp techniques, that astrocytes release a negative allosteric modulator of the gamma-aminobutyric acid type A receptor (GABAA receptor) with beta-carboline-like properties, thus, likely to act at the benzodiazepine site. Here, using patch-clamp and binding techniques, we confirm that the low-molecular-weight fraction of astroglia-conditioned medium (ACM lmf) contains a factor(s) that negatively modulates GABAA-receptor function. This factor, like beta-carbolines, enhances the specific binding of [35S]t-butyl bicyclophosphorothionate (TBPS) to adult rat cortical membranes in the presence of GABA. However, it fails to interact with various ligands of the benzodiazepine (BZD) site of the GABAA receptor ([3H]flunitrazepam, [3H]Ro 15-1788 and [3H]Ro 15-4513). The question of the actual binding site of the astroglia-derived factor on the GABAA receptor, thus, remains open and can be addressed only after the purification of the active molecule(s) of ACM Imf has been completed, and a labeled form of the endogenous ligand becomes available. Taken together, however, the data suggest that type 1 astrocytes are able to modulate the effects of the main inhibitory neurotransmission in the central nervous system. [less ▲]Detailed reference viewed: 18 (1 ULg)
Quantitative assessment by western-blot of proteins expressed by different cell types involved in inhibition and promotion of regeneration in the lesioned spinal cord.
; Martin, Didier ; Leprince, Pierre et al
Conference (1995, September 21)Detailed reference viewed: 1 (0 ULg)
Effects of macrophage grafts on the expression of glial and neuronal markers in the lesioned adult rat spinal cord: a combined immunocytochemical and biochemical study.
; Martin, Didier ; Leprince, Pierre et al
Conference (1995, May 09)Detailed reference viewed: 3 (0 ULg)
Septicemies et endocardites sur sondes endocavitaires de stimulateur cardiaque; indications chirurgicales et resultats.
Leprince, Pierre ; ; et al
in Archives des Maladies du Coeur et des Vaisseaux (1995), 88(2), 241-6
Endocarditis of transvenous pacing leads is a rare condition. The authors review a series of 15 patients who developed bacteriologically proven septicaemia and/or endocarditis related to transvenous ... [more ▼]
Endocarditis of transvenous pacing leads is a rare condition. The authors review a series of 15 patients who developed bacteriologically proven septicaemia and/or endocarditis related to transvenous pacing leads, operated between 1988 and 1993. The interval between the last manipulation of the pacemaker and the onset of endocarditis was about 6 months. Six patients had had haematoma and/or infection of the pacemaker site. Endocarditis presented with chronic pyrexia (14 cases) associated with septicaemia (6 cases) and chronic local suppuration (1 case). The interval between the beginning of the pyrexia and the diagnosis was 3.4 months. Echocardiography showed a mass attached to the pacing lead in 8 cases and tricuspid valve vegetations in 4 cases. Blood cultures were positive in 13 patients and local wound swabs identified the organism in 1 patient. The commonest causal agent was the staphylococcus (epidermis in 7 cases, aureus in 4 cases). Appropriate antibiotic therapy was only effective in 1 case. The surgical indication in 13 cases was persistence of infection associated with pulmonary embolism (3) or tricuspid regurgitation (2). Complete ablation of the prosthetic material was performed by a peripheral vascular approach (2 cases), by a right atrial approach (1 case) and under cardiopulmonary bypass in 12 cases. The peroperative findings were of tricuspid valve vegetations (4 cases), thrombi on the pacing lead (7 cases) or in the right heart chambers (2 cases) or pulmonary artery (2 cases). The associated procedures performed under cardiopulmonary bypass were tricuspid valve repair (2 cases) and pulmonary thrombectomy (2 cases). Temporary and permanent epicardial leads were implanted in 10 patients.(ABSTRACT TRUNCATED AT 250 WORDS) [less ▲]Detailed reference viewed: 3 (0 ULg)
Astroglia-Released Factor Shows Similar Effects as Benzodiazepine Inverse Agonists
; Belachew, Shibeshih ; et al
in Journal of Neuroscience Research (1994), 39(4), 364-76
Media conditioned by cultured neonatal cerebral cortex microexplants (CCM) or astrocytes (ACM) contain low molecular weight (< 1,000 Da) substance(s) which inhibits the gamma aminobutyric acid (GABA ... [more ▼]
Media conditioned by cultured neonatal cerebral cortex microexplants (CCM) or astrocytes (ACM) contain low molecular weight (< 1,000 Da) substance(s) which inhibits the gamma aminobutyric acid (GABA)-induced inward current recorded in cerebellar granule cells and hippocampal neurons in culture using the whole-cell patch-clamp technique. This effect is specific for CCM and ACM, as medium conditioned by PC12 cells (PC12CM) does not affect the GABA response of these cells. It is also specific for GABA-induced currents because glutamate-induced currents do not change either in amplitude or in shape in the presence of CCM or ACM. The inhibitory effect on the GABA response in cerebellar granule cells of both ACM and CCM could be suppressed by flumazenil, a specific benzodiazepine (BZD) antagonist and could be mimicked by two BZD inverse agonists. These data thus demonstrate the presence of a BZD inverse agonist-like activity in CCM and ACM. This effect of ACM on different neuronal cell types was heterogenous since no detectable effect could be observed on the GABA-induced current in GABA-responsive dorsal root ganglion (DRG) neurons, presumably reflecting a functional heterogeneity of the GABAA receptors present in these different neuronal subsets. By the release of such an endogenous BZD inverse agonist-like activity, glia cells could possibly modulate GABAA receptor-mediated responses. [less ▲]Detailed reference viewed: 17 (5 ULg)
Hypothèses étiopathologiques récentes dans la maladie d'Alzheimer: apports de la biologie moléculaire
Moonen, Gustave ; Rogister, Bernard ; Leprince, Pierre
in Revue Médicale de Liège (1994), 49(2), 78-83Detailed reference viewed: 5 (1 ULg)
Metalloproteinases and serine proteases activities in mixed spheroids of mouse B16 melanoma cells and fibroblasts
; ; Leprince, Pierre et al
in International Journal of Oncology (1994), 5Detailed reference viewed: 5 (0 ULg)
Evaluation of Matrix Metalloproteinases and Serine Proteases Activities in Three B16 Melanoma Cell Lines with Distinct Tumorigenic Potential
; ; Leprince, Pierre et al
in Anticancer Research (1994), 14(3A, May-Jun), 841-6
Mouse B16 melanoma cells (B16, parental line) and two derived clones either pigmented (B16P) or non pigmented (B16NP) were cultured as monolayers (2D) or on agar, as aggregates (3D). The productions of ... [more ▼]
Mouse B16 melanoma cells (B16, parental line) and two derived clones either pigmented (B16P) or non pigmented (B16NP) were cultured as monolayers (2D) or on agar, as aggregates (3D). The productions of gelatinases A and B (72 kDa and 92 kDa type IV collagenases) and their inhibitors (TIMP1 and TIMP2), plasminogen activators (PAs) and plasminogen activator inhibitors (PAI) were investigated. The B16 cell lines did not secrete any gelatinase, but they secreted TIMP2, tissue-type (t-PA), urokinase-type (u-PA) plasminogen activators and PAI-1 like activities. High levels of PAI activity were determined in conditioned media and cellular extracts of B16NP, which could account for the lower tumorigenic potential of these cells. In 3D cultures, the cellular extracts of the three cell lines contained essentially u-PA activity. This activity could contribute to the greater tumorigenic and invasive capacities of B16, B16P and B16NP when cultured in 3D. [less ▲]Detailed reference viewed: 10 (3 ULg)
Transforming growth factor ß as a neuronoglial signal during peripheral nervous sytem response to injury.
Rogister, Bernard ; ; Leprince, Pierre et al
in Journal of Neuroscience Research (1993), 34Detailed reference viewed: 56 (25 ULg)
Syngeneic Grafting of Adult Rat Drg-Derived Schwann Cells to the Injured Spinal Cord
Martin, Didier ; Schoenen, Jean ; et al
in Brain Research Bulletin (1993), 30(3-4), 507-14
A subdural inflatable micro-balloon was used to induce closed traumatic contusion to adult rat spinal cord. This spinal cord injury model was associated with reproducible and graded neurological deficits ... [more ▼]
A subdural inflatable micro-balloon was used to induce closed traumatic contusion to adult rat spinal cord. This spinal cord injury model was associated with reproducible and graded neurological deficits and histopathological alterations. At various delays after injury, transplantations of syngeneic adult cultured dorsal root ganglion-derived Schwann cells were performed into the spinal cord lesion. The transplants were well integrated and reduced the microcystic posttraumatic cavitation as well as the gliosis. Schwann cells transplants were invaded by numerous regenerating neurites most of which, based upon their neurotransmitter contents, seem to originate from the dorsal root ganglion. [less ▲]Detailed reference viewed: 12 (2 ULg)
Plasticity of Developing and Adult Dorsal Root Ganglion Neurons as Revealed in Vitro
; Ribbens, Clio ; Martin, Didier et al
in Brain Research Bulletin (1993), 30(3-4), 231-7
We review recent data on the plasticity of dorsal root ganglion (DRG) neurons as revealed during cultivation in vitro. Some experiments on cultured developing DRG neurons and on adult DRG neurons in vivo ... [more ▼]
We review recent data on the plasticity of dorsal root ganglion (DRG) neurons as revealed during cultivation in vitro. Some experiments on cultured developing DRG neurons and on adult DRG neurons in vivo are also mentioned. Cultured developing and adult DRG neurons can be switched from an apolar to a multipolar phenotype by fetal calf serum or fibronectin. The effect is concentration dependent and occurs through an early modification of cell-substratum interaction. Adult DRG neurons synthesize and release within hours after injury TGF beta-1, which is a mitogen and a differentiation factor for Schwann cells. Finally, adult DRG neurons express in vitro neurotransmitters that are not expressed in vivo. This neurotransmitter plasticity can be modulated in vitro by some growth factors and in vivo by distal or proximal axotomy. [less ▲]Detailed reference viewed: 32 (3 ULg)
In Vitro and in Vivo Modulation of 5-Hydroxytryptamine-, Thyrotropin-Releasing Hormone- and Calcitonin-Gene Related Peptide-Like Immunoreactivities in Adult Rat Sensory Neurons
; Martin, Didier ; Sadzot-Delvaux, Catherine et al
in Neuroscience (1992), 51(2), 401-10
In a previous work we have shown that culturing adult rat dorsal root ganglia neurons modifies their neurotransmitter phenotype in such a way that cultured neurons synthesize transmitters that are not ... [more ▼]
In a previous work we have shown that culturing adult rat dorsal root ganglia neurons modifies their neurotransmitter phenotype in such a way that cultured neurons synthesize transmitters that are not found in situ, while several other transmitters are expressed in a much higher percentage of neurons in culture than in situ [Schoenen J. et al. (1989) J. Neurosci. Res. 22, 473-487]. The aim of the present study was to investigate the origin and the nature of the relevant environmental signals that allow this plasticity to be expressed, focusing on three neurotransmitters: 5-hydroxytryptamine, thyrotropin-releasing hormone and calcitonin-gene related peptide. The main results can be summarized as follows: (1) culturing cells in fetal calf serum or on feeder layers of astrocytes, Schwann cells or fibroblasts partially inhibits the serotoninergic phenotype of dorsal root ganglia neurons; (2) in vivo disconnection of dorsal root ganglia from their spinal targets but not from their peripheral or supraspinal targets induces a significant increase of the percentage of 5-hydroxytryptamine- and thyrotropin-releasing hormone-positive neurons in disconnected ganglia; (3) growth factors such as ciliary neuronotrophic factor or basic fibroblast growth factor but not nerve growth factor repress 5-hydroxytryptamine and calcitonin gene-related peptide immunoreactivity in cultured sensory neurons. In conclusion, neurotransmitter gene expression of adult dorsal root ganglia neurons is controlled by complex influences. Our data suggest that thyrotropin-releasing hormone and 5-hydroxytryptamine gene expression are tonically repressed in vivo by factors originating from the spinal segmental level and that growth factors such as ciliary neurotrophic factor or basic fibroblast growth factor could be potential vectors of this repressing effect. [less ▲]Detailed reference viewed: 44 (25 ULg)
Experimental Acute Traumatic Injury of the Adult Rat Spinal Cord by a Subdural Inflatable Balloon: Methodology, Behavioral Analysis, and Histopathology
Martin, Didier ; Schoenen, Jean ; et al
in Journal of Neuroscience Research (1992), 32(4), 539-50
We describe an experimental model to produce closed traumatic injuries to the spinal cord of adult rats. This model uses an inflatable balloon that is introduced in the dorsal subdural space and moved to ... [more ▼]
We describe an experimental model to produce closed traumatic injuries to the spinal cord of adult rats. This model uses an inflatable balloon that is introduced in the dorsal subdural space and moved to a location rostral to the laminectomy site. The spinal cord trauma can be graded by varying either the duration of compression or the volume of saline used to inflate the balloon. The locomotor deficit of animals with various degrees of injury has been assessed at increasing delays after trauma. The parameters generating transient or definitive deficits of varying intensity were defined. Some injured animals underwent nuclear magnetic resonance imaging. Detailed histopathological studies demonstrated that the extent of the spinal lesion was significantly correlated with the physical parameters of compression and with the severity of the behavioral deficit. [less ▲]Detailed reference viewed: 18 (3 ULg)
Mécanismes de communication cellulaire dans le système nerveux périphérique en régénération
Leprince, Pierre ; ; Rogister, Bernard et al
in Revue Médicale de Liège (1992), 47(3), 115-8Detailed reference viewed: 29 (2 ULg)
Etude des activateurs du plasminogène et de leurs inhibiteurs dans le système nerveux en développement.
Schoenen, Jean ; ; et al
Conference (1992)Detailed reference viewed: 6 (1 ULg)
Plasticité des neurones sensoriels primaires chez le rat adulte. Etude in vitro et in vivo.
Moonen, Gustave ; ; Martin, Didier et al
Conference (1991, November 16)
In vitro and in vivo modulation of transmitter phenotype in adult rat DRG neurons.
Moonen, Gustave ; Schoenen, Jean ; et al
Conference (1991, August 11)Detailed reference viewed: 1 (0 ULg)
A model of traumatic paraplegia in the rat : behavioral and anatomical studies; preliminary results of neuronal and non-neuronal transplants.
Schoenen, Jean ; Moonen, Gustave ; Martin, Didier et al
Conference (1991, August 11)Detailed reference viewed: 2 (0 ULg)