References of "Minet, Arlette"
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See detailUnusual Amino Acids and Monofluoroacetate from Dichapetalum michelsonii (Umutambasha), a Toxic Plant from Rwanda
Esters, Virginie ULg; Karangwa, Charles; Tits, Monique ULg et al

in Planta Medica (2013), 79

In the course of our investigations on Umutambasha in order to identify its convulsant principles, small quantities of monofluoroacetate were observed in stem bark, leaves, and fruits of this plant newly ... [more ▼]

In the course of our investigations on Umutambasha in order to identify its convulsant principles, small quantities of monofluoroacetate were observed in stem bark, leaves, and fruits of this plant newly identified as Dichapetalum michelsonii Hauman. Conclusive evidence for a monofluoroacetate presence came from its isolation from the freeze-dried extract of stem bark. Three free unusual amino acids, named N-methyl-α-alanine, N-methyl-β-alanine, and 2,7-diaminooctan-1,8-dioic acid, described for the first time in a plant, and known trigonelline were also isolated from the stem bark of D. michelsonii. Structure elucidations were mainly achieved by spectroscopic methods (1H-NMR, 2D-NMR, MS) and by comparison with authentic references. These unusual amino acids were detected by a fast, reliable TLC analysis in all our batches of Umutambasha, suggesting that they could be used for identification purposes in case of human or livestock intoxications. Finally, EEG recordings and behavioural observations performed in mice suggested that the convulsive patterns produced by Umutambasha are the consequence of monofluoroacetate presence in D. michelsonii. [less ▲]

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See detailCharacterization of the neurotoxicity induced by the extract of Magnistipula butayei (Chrysobalanaceae) in rat: Effects of a new natural convulsive agent
Karangwa, Charles; Esters, Virginie ULg; Tits, Monique ULg et al

in Toxicon (2007), 49(8), 1109-1119

This study was designed to document convulsant and neurotoxic properties of extracts of a tropical tree, Magnistipula butayei subsp. Montana, and to investigate the involvement of the glutamatergic system ... [more ▼]

This study was designed to document convulsant and neurotoxic properties of extracts of a tropical tree, Magnistipula butayei subsp. Montana, and to investigate the involvement of the glutamatergic system in these effects. Continuous behavioral observations and electroencephalographic (EEG) records were obtained after per os administration of an aqueous extract of Magnistipula (MBMAE) in rats. MBMAE (800 mg/kg) induced behavioral changes resembling motor limbic seizures: staring and head tremor, automatisms, forelimb clonic movements and violent tonic-clonic seizures leading to death in all animals. Concomitantly, important seizure activity that gradually evolved to epileptiform activity was recorded on the EEG. Moreover, c-Fos immunohistochemistry has revealed an increased c-Fos expression in the dentate gyrus and in piriform, peri- and entorhinal cortices 2 and 4h after treatment. This expression pattern suggested that the mechanism of action for the MBMAE is similar to that observed in glutamate-induced models of epilepsy. The MBMAE increased cell death also in hippocampal cell cultures. Furthermore, the build-up of convulsive activity and epileptic discharges induced by MBMAE in rat were abolished by MK-801, an NMDA receptor antagonist. Our study suggests that MBMAE contains a potent toxin, with a powerful neurotoxic activity in rat, and corresponding to a new natural component(s) that act as an NMDA-mediated convulsant molecule. [less ▲]

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See detailDisrupting the melanin-concentrating hormone receptor 1 in mice leads to cognitive and NMDA response deficit
Grisar, Thierry ULg; Adamantidis, Antoine ULg; Thomas, Elizabeth et al

in Journal of the Neurological Sciences (2005, November 15), 238(Suppl. 1), 288

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See detailDisrupting the melanin-concentrating hormone receptor 1 in mice leads to cognitive deficits and alterations of NMDA receptor function.
Adamantidis, Antoine ULg; Thomas, Elizabeth; Foidart, Agnès ULg et al

in European Journal of Neuroscience (2005), 21(10), 2837-44

In order to investigate the physiological properties of the melanin-concentrating hormone (MCH) we have generated and used mice from which the MCH receptor 1 gene was deleted (MCHR1(Neo/Neo) mice ... [more ▼]

In order to investigate the physiological properties of the melanin-concentrating hormone (MCH) we have generated and used mice from which the MCH receptor 1 gene was deleted (MCHR1(Neo/Neo) mice). Complementary experimental approaches were used to investigate alterations in the learning and memory processes of our transgenic model. The ability of the knockout strain to carry out the inhibitory passive avoidance test was found to be considerably impaired although no significant differences were observed in anxiety levels. This impaired cognitive property prompted us to explore modifications in N-methyl D-aspartate (NMDA) responses in the hippocampus. Intracellular recordings of CA1 pyramidal neurons in hippocampal slices from the MCHR1(Neo/Neo) mice revealed significantly decreased NMDA responses. Finally, using in situ hybridization we found a 15% reduction in NMDAR1 subunit in the CA1 region. These results show for the first time a possible role for MCH in the control of the function of the NMDA receptor. [less ▲]

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See detailThe genetic absence epilepsy rat from Strasbourg (GAERS), a rat model of absence epilepsy: Computer modeling and differential gene expression
Lakaye, Bernard ULg; Thomas, E.; Minet, Arlette ULg et al

in Epilepsia (2002), 43(Suppl. 5), 123-129

Purpose: We present results obtained by computer modeling of the thalamic network and differential gene expression analysis in a rat strain with absence epilepsy, the genetic absence epilepsy rat from ... [more ▼]

Purpose: We present results obtained by computer modeling of the thalamic network and differential gene expression analysis in a rat strain with absence epilepsy, the genetic absence epilepsy rat from Strasbourg (GAERS). Methods: (a) Computer modeling used equations from the Hodgking-Huxley model with a circuit of 13 reticular thalamic (nRt) and 39 thalamocortical (TC) neurons; (b) gene-expression analysis using differential mRNA display (DD), in situ hybridization, Northern blotting, and competitive reverse transcriptase-polymerase chain reaction (RT-PCR). Results: (a) Computer modeling showed an increased network synchrony in the thalamic circuit as the value of conductance of low-voltage activated calcium channel (LVACC) is increased. (b) Using differential mRNA display, a 40% upregulation of the H-ferritin mRNA in the hippocampus was demonstrated. Looking for some candidate genes of the VACC family, no difference was found in the alpha1G mRNA expression between GAERS and control animals, whereas a decreased expression of the alpha1E subunit was observed in the cerebellum and the brainstem of the GAERS. This phenomenon was not observed in young animals when the epileptic phenotype is not expressed. Conclusions: The use of computer modeling appeared to be an efficient way to evaluate the impacts of electrophysiologic findings in vivo from single cells on an entire circuit. No clear single gene defect was revealed so far in GAERS. More information could arise from linkage analysis. However, some brain structures like hippocampus or cerebellum classically not known to be involved in the production of absence spike-and-wave discharges could in fact participate in the development of this phenotype. [less ▲]

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See detailIncreased Expression of mRNA Encoding Ferritin Heavy Chain in Brain Structures of a Rat Model of Absence Epilepsy
Lakaye, Bernard ULg; de Borman, B.; Minet, Arlette ULg et al

in Experimental Neurology (2000), 162(1), 112-20

Differential mRNA display was carried out to find genes that are differentially regulated in the brain of a rat strain with absence epilepsy, the genetic absence epilepsy rats from Strasbourg (GAERS ... [more ▼]

Differential mRNA display was carried out to find genes that are differentially regulated in the brain of a rat strain with absence epilepsy, the genetic absence epilepsy rats from Strasbourg (GAERS). Among the 32 differentially displayed cDNA fragments actually cloned and sequenced, one shows 100% identity with the rat heavy chain ferritin (H-ferritin) mRNA. Northern blot analysis confirmed the up-regulation of the H-ferritin mRNA. Using dot blotting, a 40% increase in expression was reported in the subcortical forebrain of the adult GAERS, while cortex, brain stem, and cerebellum appeared unmodified. This change was not observed in the brain of 25-day-old rats, an age at which the epileptic phenotype is not present. By in situ hybridization, the enhanced expression was localized in the hippocampus. The increase in mRNA encoding H-ferritin was not immunodetected at the protein level by Western blotting. These results are not apparently related to the neural substrate of SWD or to the distribution of local increase in glucose metabolism previously described in the GAERS. It is hypothesized that the up-regulation of the H-ferritin mRNA is part of a mechanism protecting the hippocampus, a seizure-prone area, against a possible overactivation during absence seizures. [less ▲]

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See detailImmunocytochemical localization of ionotropic glutamate receptors subunits in the adult quail forebrain
Cornil, Charlotte ULg; Foidart, Agnès ULg; Minet, Arlette ULg et al

in Journal of Comparative Neurology (The) (2000), 428

The excitatory amino acid glutamate is implicated in the central control of many neuroendocrine and behavioral processes. The ionotropic glutamate receptors are usually divided into the N-methyl-D ... [more ▼]

The excitatory amino acid glutamate is implicated in the central control of many neuroendocrine and behavioral processes. The ionotropic glutamate receptors are usually divided into the N-methyl-D-aspartate (NMDA) and non-NMDA (kainate and AMPA) subtypes. Subunits of these receptors have been cloned in a few mammalian species. Information available in birds is more limited. In quail, we recently demonstrated that glutamate agonists (kainate, AMPA, and NMDA) rapidly (within minutes) and reversibly decrease in vitro aromatase activity like several other manipulations affecting intracellular HCa21 pools. Aromatase catalyzes the conversion of androgens into estrogens which is a limiting step in the control by testosterone of many behavioral and physiologic processes. Therefore, glutamate could control estrogen production in the brain, but the anatomic substrate supporting this effect is poorly understood. In quail, aromatase is mainly localized in the preoptic-hypothalamic-limbic system. We visualized here the distribution of the major ionotropic glutamate receptors in quail by immunocytochemical methods by using commercial primary antibodies raised against rat glutamate receptor 1 and receptors 2-3 (GluR1, GluR2/3: AMPA subtype, Chemicon, CA), rat glutamate receptors 5-7 (GluR5-7: kainate subtype, Pharmingen, CA), and rat NMDA receptors (NMDAR1, Pharmingen, CA). Dense and specific signals were obtained with all antibodies. The four types of receptors are broadly distributed in the brain, and, in particular, immunoreactive cells are identified within the major aromatase cell groups located in the medial preoptic nucleus, ventromedial hypothalamus, nucleus striae terminalis, and nucleus taeniae. Dense specific populations of glutamate receptor immunoreactive cells are also present with a receptor subtype-specific distribution in broad areas of the telencephalon. The distribution of glutamate receptors, therefore, is consistent with the idea that these receptors could be located at the surface of aromatase-containing cells and mediate the rapid regulation of aromatase activity in a direct manner. [less ▲]

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See detailExpression of Mrna Encoding Alpha1e and Alpha1g Subunit in the Brain of a Rat Model of Absence Epilepsy
de Borman, B.; Lakaye, Bernard ULg; Minet, Arlette ULg et al

in Neuroreport (1999), 10(3), 569-74

Low voltage-activated calcium channels are thought to play a key role in the generation of spike and waves discharges characteristic of absence epilepsy. Therefore, the expression level of mRNA encoding ... [more ▼]

Low voltage-activated calcium channels are thought to play a key role in the generation of spike and waves discharges characteristic of absence epilepsy. Therefore, the expression level of mRNA encoding calcium channel alpha1E and alpha1G subunits was measured in the brain of genetic absence epilepsy rats from Strasbourg (GAERS). Using quantitative RT-PCR and in situ hybridization, no difference was found in alpha1G mRNA expression between GAERS and control animals, while a decreased expression of alpha1E was seen in the cerebellum and the brain stem of the GAERS. This phenomenon was not observed in young animals when the epileptic phenotype is not expressed. [less ▲]

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See detailThe Molecular Neuron-Glia Couple and Epileptogenesis
Grisar, Thierry ULg; Lakaye, Bernard ULg; Thomas, E. et al

in Advances in Neurology (1999), 79

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See detailThe molecular neuron-glia couple and epileptogenesis
Grisar, Thierry ULg; Lakaye, Bernard ULg; Thomas, Elizabeth et al

in Delgado-Escueta, A. V.; Wilson, W. A.; Olsen, R. W. (Eds.) et al Jasper's Basic Mechanisms of the Epilepsies, 3rd edition (1999)

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See detailCloning of the Rat Brain Cdna Encoding for the Slc-1 G Protein-Coupled Receptor Reveals the Presence of an Intron in the Gene
Lakaye, Bernard ULg; Minet, Arlette ULg; Zorzi, Willy ULg et al

in Biochimica et Biophysica Acta (1998), 1401(2), 216-20

In order to isolate new G protein-coupled receptors expressed in the cerebral cortex, a set of degenerate oligonucleotides corresponding to the third and seventh transmembrane segment were synthetized ... [more ▼]

In order to isolate new G protein-coupled receptors expressed in the cerebral cortex, a set of degenerate oligonucleotides corresponding to the third and seventh transmembrane segment were synthetized. Their use in PCR on rat brain cortex mRNA amplified several cDNA fragments. One of them, a 526 bp sequence, encoded for what was at that time an unknown G protein-coupled receptor. An oligonucleotide derived from the sequence was then used as a probe to isolate the receptor cDNA from a rat brain cDNA library. It encodes for a 353aa protein with seven transmembrane segments, three consensus N-glycosylation sites at the amino terminus and several potential phosphorylation sites in the intracellular loops. This protein shares 91% overall identity with a recently cloned human somatostatin-like receptor of 402aa named SLC-1. This suggests that we have cloned the rat orthologue of the human SLC-1. However, the extracellular N-terminus of the human receptor is 49 amino acids longer and shows 50% identity with the rat one. Because the human sequence was deduced from genomic DNA, we suspected the presence of an intron in the gene. This was confirmed by PCR using primers spanning the intron. On the basis of the sequence of a 128 kb fragment of chromosome 22 encompassing the SLC-1 gene, we were able to deduce a corrected amino acids sequence for the human receptor. So both rat and human SLC-1 receptors are 353aa long, with three consensus N-glycosylation sites. They share 96% identity at the amino acid level and are encoded by a gene containing one intron in the coding sequence. [less ▲]

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See detailThe Fate of Mitochondrial Dnas of Mt+ and Mt- Origin in Gametes and Zygotes of Chlamydomonas
Beckers, M. C.; Munaut, Carine ULg; Minet, Arlette ULg et al

in Current Genetics (1991), 20(3), 239-43

In order to study the mechanism responsible for the uniparental transmission of the mitochondrial genome in crosses between Chlamydomonas reinhardtii and C. smithii, we have analyzed the fate of ... [more ▼]

In order to study the mechanism responsible for the uniparental transmission of the mitochondrial genome in crosses between Chlamydomonas reinhardtii and C. smithii, we have analyzed the fate of mitochondrial DNA during gametogenesis, zygospore differentiation and sporulation by hybridization experiments. Both mt+ and mt- gametes contain the same amount of mitochondrial DNA and the two parental genomes persist for several days in the zygotes. The DNA of mt+ origin is slowly eliminated during the period of zygote maturation. Light is required for total elimination of mt+ mitochondrial DNA in the zygospores. Using appropriate restriction enzymes, we have been unable to detect methylation of the mitochondrial DNA during gametogenesis or zygospore formation. The possibility that the mt+ mitochondria themselves are specifically eliminated in the course of zygote maturation is discussed. [less ▲]

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