References of "Lemaire, Christian"
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See detailDecomposition of metabolic brain clusters in the frontal variant of frontotemporal dementia
Salmon, Eric ULg; Kerrouche, Nacer; Herholz, Karl et al

in NeuroImage (2006), 30(3), 871-878

Previous studies that measured brain activity in frontotemporal dementia (FTD) used univariate analyses, examining each region of interest separately. We explored in a multicenter European research ... [more ▼]

Previous studies that measured brain activity in frontotemporal dementia (FTD) used univariate analyses, examining each region of interest separately. We explored in a multicenter European research program the principal brain clusters characterized by a common variability in cerebral metabolism in FTD. Seventy patients with frontal variant (fv) FTD were selected according to international clinical recommendations; principal component analysis (PCA) was performed on FDG-PET metabolic images, looking for covariance clusters in this large population. A first metabolic cluster included most of the lateral and medial prefrontal cortex, bilaterally; PC1 scores correlated with performances on memory and executive neuropsychological tasks. Moreover, FDG-PET images in fv-FTD were further characterized by a metabolic covariance in two clusters comprising the subcallosal medial frontal region, the temporal pole, medial temporal structures and the striatum, separately in the left and in the right hemisphere. The study provides original data-driven arguments for metabolic involvement of separate brain clusters in the rostral limbic system, corresponding to pathological poles differentially affected in each FTD patient. [less ▲]

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See detailDEVELOPPEMENT D'INHIBITEURS SELECTIFS DE LA TRYPTOPHANE HYDROXYLASE
Giacomelli, Fabrice ULg; Luxen, André ULg; Lemaire, Christian ULg et al

Conference (2006, February 03)

Comprendre la façon dont le cerveau travaille et en particulier le mode de communication de ses cellules est un rêve que beaucoup de chercheurs caressent. A l’heure actuelle, une des rares certitudes à ... [more ▼]

Comprendre la façon dont le cerveau travaille et en particulier le mode de communication de ses cellules est un rêve que beaucoup de chercheurs caressent. A l’heure actuelle, une des rares certitudes à son sujet est qu’un de ses modes de transmission d’informations utilise des « messagers » chimiques appelés neurotransmetteurs. Parmi ceux-ci, la sérotonine (5-HT) revêt une importance particulière. En effet, la 5-HT est impliquée dans de nombreuses fonctions (apprentissage, locomotion, sommeil,…) et pathologies (dépressions, démences, schizophrénies,…). Dès lors, l'étude in vivo chez l'homme des neurones sérotoninergiques ainsi que la quantification de la vitesse de biosynthèse de la 5-HT sont des domaines d'études fondamentaux pour lesquels la tomographie à émission de positons (TEP) constitue un outil de choix. Pour mener à bien ces différentes expérimentations, deux stratégies sont envisageables : - L’emploi d'un traceur capable de suivre la chaîne métabolique du tryptophane conduisant à la 5-HT tout en évitant les autres voies métaboliques. - L’utilisation d'un inhibiteur de la TrpOH (enzyme limitant du processus). Dans le cadre de cette présentation, nous nous intéresserons plus particulièrement à la deuxième stratégie. [less ▲]

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See detailOrbitofrontal dysfunction related to both apathy and disinhibition in frontotemporal dementia
Peters, Frederic; Perani, Daniela; Herholz, Karl et al

in Dementia & Geriatric Cognitive Disorders (2006), 21(5-6), 373-379

Orbitofrontal metabolic impairment is characteristic of the frontal variant of frontotemporal dementia (fv-FTD), as are early changes in emotional and social conduct. Two main types of behavioral ... [more ▼]

Orbitofrontal metabolic impairment is characteristic of the frontal variant of frontotemporal dementia (fv-FTD), as are early changes in emotional and social conduct. Two main types of behavioral disturbances have been distinguished in fv-FTD patients: apathetic and disinhibited manifestations. In this study, we searched for relationships between brain metabolism and presence of apathetic or disinhibited behavior. Metabolic activity and behavioral data were collected in 41 fv-FTD patients from European PET centers. A conjunction analysis of the PET data showed an expected impairment of metabolic activity in the anterior cingulate, ventromedial and orbital prefrontal cortex, the dorsolateral prefrontal cortex and the left anterior insula in fv-FTD subjects compared to matched controls. A correlation was observed between disinhibition scores on the Neuropsychiatric Inventory scale and a cluster of voxels located in the posterior orbitofrontal cortex ( 6, 28, - 24). Comparison of brain activity between apathetic and nonapathetic fv-FTD patients from two centers also revealed a specific involvement of the posterior orbitofrontal cortex in apathetic subjects ( 4, 22, - 22). The results confirm that the main cerebral metabolic impairment in fv-FTD patients affects areas specializing in emotional evaluation and demonstrate that decreased orbitofrontal activity is related to both disinhibited and apathetic syndromes in fv-FTD. Copyright (C) 2006 S. Karger AG, Basel. [less ▲]

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See detailSynthesis of protected meso-diaminopimelic acid.
Teller, N.; Lemaire, Christian ULg; Plenevaux, Alain ULg et al

Poster (2005, October 10)

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See detailSynthesis of anhydro-muranic acid derivatives as substrates for MurNAc amidase.
Mercier, F.; Lemaire, Christian ULg; Plenevaux, Alain ULg et al

Poster (2005, October 10)

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See detailRadiochemical Synthesis of OCH2F-[18F]MPPF a New Analogue of p-[18F]MPPF for the Study of 5-HT1A Receptors.
Defraiteur, C.; Lemaire, Christian ULg; Luxen, André ULg et al

in Journal of Labelled Compounds & Radiopharmaceuticals (2005), 48

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See detailEx Vivo Evaluation of p-[18F]D-MPPF for the Study of 5-HT1A Receptors.
Defraiteur, C.; Lemaire, Christian ULg; Luxen, André ULg et al

in Journal of Labelled Compounds & Radiopharmaceuticals (2005), 48

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See detailNew Methods For Halogenation of [18F]Fluorinated Benzyl Derivatives.
Kech, C.; Lemaire, Christian ULg; Brichard, L. et al

in Journal of Labelled Compounds & Radiopharmaceuticals (2005), 48

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See detailHighly enantioselective synthesis of no-carrier-added 6-[18F]Fluoro-L-dopa by chiral phase-transfer alkylation
Lemaire, Christian ULg; Gillet, Steve; Guillouet, Stéphane et al

in European Journal of Organic Chemistry (2004), (13), 2899-2904

[F-18]Fluoro-L-dopa, an important radiopharmaceutical for positron emission tomography (PET), has been synthesized using a phase-transfer alkylation reaction. A chiral quaternary ammonium salt derived ... [more ▼]

[F-18]Fluoro-L-dopa, an important radiopharmaceutical for positron emission tomography (PET), has been synthesized using a phase-transfer alkylation reaction. A chiral quaternary ammonium salt derived from a Cinchona alkaloid served as phase-transfer catalyst for the enantioselective alkylation of a glycine derivative. The active methylene group of this Schiff-base substrate was deprotonated with cesium hydroxide and rapidly alkylated by the 2-[F-18]fluoro-4,5-dimethoxybenzyl halide (X = Br, I). The reaction proceeded with high yield (> 90%) at 0 degreesC or room temperature in various solvents such as toluene or dichloromethane. Preparation of the [F-18]alkylating agent on a solid support was developed. After labelling, the labeled [F-18]fluoroveratraldehyde was trapped on a (t)C18 cartridge and then converted on the cartridge into the corresponding benzyl halide derivatives by addition of aqueous sodium borohydride and gaseous hydrobromic or -iodic acid. Hydrolysis and purification by preparative HPLC made 6-[F-18]fluoro-L-dopa ready for human injection in a 25-30% decay-corrected radiochemical yield in a synthesis time of 100 min. The product was found to be chemically, radiochemically and enantiomerically pure (ee > 95%). (C) Wiley-VCH Verlag GmbH [less ▲]

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See detailTissue distribution and metabolism of D-p-[18F]MPPF in rats.
Defraiteur, C.; Muroni, S.; Lemaire, Christian ULg et al

in Journal of Nuclear Medicine : Official Publication, Society of Nuclear Medicine (2004), 45(S2), 444

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See detailRadiochemical Synthesis of p-[18F]Desmethyl-MPPF (p-[18F]D-MPPF) for the Study of 5-HT1A Receptors
Defraiteur, Caroline; Plenevaux, Alain ULg; Lemaire, Christian ULg et al

in Journal of Labelled Compounds & Radiopharmaceuticals (2003, August), 46(S1), 157

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See detailRadiosynthèses d'antagonistes des récepteurs 5-HT1A.
Defraiteur, C.; Plenevaux, Alain ULg; Lemaire, Christian ULg et al

Poster (2003, June 13)

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See detailMise au point de sondes pour l'étude du système sérotoninergique par tomographie à émission de positons (TEP)
Giacomelli, Fabrice ULg; Lemaire, Christian ULg; Plenevaux, Alain ULg et al

Poster (2003, June 13)

La quantification de la vitesse de biosynthèse de la sérotonine ainsi que l'étude in vivo chez l'homme sont, du fait de l'implication cruciale des neurones sérotoninergiques dans de nombreuses fonctions ... [more ▼]

La quantification de la vitesse de biosynthèse de la sérotonine ainsi que l'étude in vivo chez l'homme sont, du fait de l'implication cruciale des neurones sérotoninergiques dans de nombreuses fonctions et pathologies cérébrales, des domaines d'études fondamentaux pour lesquels la TEP constitue un outil de choix. Ces différentes expérimentations peuvent être conduites suivant deux optiques: (i) emploi d'un traceur capable de suivre la chaîne métabolique du tryptophane conduisant à la sérotonine tout en évitant les autres voies métaboliques. (ii) utilisation d'un inhibiteur de la tryptophane hydroxylase (TPOH), enzyme limitante du processus. [less ▲]

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See detailRadiosynthèse de dérivés du 7-[18F]fluoroindole
Otabashi, Muhammad ULg; Giacomelli, Fabrice ULg; Lemaire, Christian ULg et al

Poster (2003, June 13)

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See detailWhole-body tumor imaging using PET and 2-18F-fluoro-l-tyrosine: Preliminary evaluation and comparison with 18F-FDG
Hustinx, Roland ULg; Lemaire, Christian ULg; Jerusalem, Guy ULg et al

in Journal of Nuclear Medicine : Official Publication, Society of Nuclear Medicine (2003), 44(4), 533-539

18F-FDG PET imaging is now established as a valuable tool for evaluating cancer patients. However, a limitation of 18F-FDG is its absence of specificity for tumor. Both protein synthesis and amino acid ... [more ▼]

18F-FDG PET imaging is now established as a valuable tool for evaluating cancer patients. However, a limitation of 18F-FDG is its absence of specificity for tumor. Both protein synthesis and amino acid transport are enhanced in most tumor cells, but their metabolism is less affected in inflammation. We therefore decided to evaluate the ability of PET with 2-18F-fluoro-L-tyrosine (18F-TYR) to visualize cancer lesions in patients compared with 18F-FDG PET. Methods: 18F-FDG PET and 18F-TYR PET were performed on 23 patients with histologically proven malignancies (11 non-small cell lung cancers (NSCLCs), 10 lymphomas, and 2 head and neck carcinomas). Fully corrected, whole-body PET studies were obtained on separate days. 18F-FDG studies were performed after routine clinical fashion. 18F-TYR studies were started 36 ± 6 min after tracer injection and a second scan centered over a reference lesion was acquired after completion of the whole-body survey-on average, 87 min after injection. Standardized uptake values (SUVs) were calculated for all abnormal foci and for various normal structures. Results were compared with pathologic or correlative studies. Results: 18F-FDG PET correctly identified 54 malignant lesions, among which 36 were also visualized with 18F-TYR (67%). 18F-TYR did not detect any additional lesion. Tumor SUVs (SUVbw, 5.2 vs. 2.5), tumor-to-muscle (7.4 vs. 2.7), and tumor-to-mediastinum activity ratios (3 vs. 1.4) were higher with 18F-FDG than with 18F-TYR. Two of 11 NSCLCs and 4 of 10 lymphomas were understaged with 18F-TYR compared with 18F-FDG. Although the NSCLC lesions missed by 18F-TYR PET were small, several large lymphoma lesions did not accumulate the tracer. In 4 patients, 18F-TYR-positive lesions coexisted with 18F-TYR-negative lesions. There was a high physiologic 18F-TYR uptake by the pancreas (average SUVbw, 10.3) and the liver (average SUVbw, 6.3). Muscle and bone marrow uptakes were also higher with 18F-TYR than with 18F-FDG: average SUVbw, 1 versus 0.7 and 2.6 versus 1.8, respectively. There was no change over time in the 18F-TYR uptake by the tumors or the normal structures. Conclusion: 18F-TYR PET is not superior to 18F-FDG PET for staging patients with NSCLC and lymphomas. [less ▲]

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See detailEffects of Alzheimer's disease on the recognition of novel versus familiar words : Neuropsychological and clinico-metabolic data
Lekeu, Françoise ULg; Van der Linden, Martial ULg; Degueldre, Christian ULg et al

in Neuropsychology (2003), 17(1), 143-154

This study explored recognition memory performance for novel versus familiar words in Alzheimer's disease (AD) patients and normal controls (NCs), using an adaptation of E. Tulving and N. Kroll's (1995 ... [more ▼]

This study explored recognition memory performance for novel versus familiar words in Alzheimer's disease (AD) patients and normal controls (NCs), using an adaptation of E. Tulving and N. Kroll's (1995) procedure. Results showed that both groups exhibited more hits and more false alarms for familiar than for novel words. The groups did not differ in the recognition of familiar words, reflecting preserved familiarity processes in AD. However, AD patients made more false alarms than NCs in the recognition of novel words, reflecting impairment of recollection processes in AD. A positron emission tomography analysis of clinico-metabolic correlations in AD patients showed a correlation between recognition of novel words and right hippocampal activity, whereas recognition of familiar words was more related to metabolic activity in the left posterior orbitofrontal cortex. [less ▲]

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See detailRadiosynthesis of 7-[18F]fluoroindole derivatives.
Otabashi, Muhammad ULg; Giacomelli, Fabrice ULg; Lemaire, Christian ULg et al

in Journal of Labelled Compounds & Radiopharmaceuticals (2003), 46

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See detailSimple device for the radiosynthesis of [carbonyl-11C]amides, esters and ketones using carbon-11 monoxide.
Brichard, L.; Del Fiore, G.; Lemaire, Christian ULg et al

in Journal of Labelled Compounds & Radiopharmaceuticals (2003), 46

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See detailSynthesis of [18F]fluorinated a-methyl-a-amino acids by phase transfer catalysis for potential PET application.
Wouters, L.; Lemaire, Christian ULg; Plenevaux, Alain ULg et al

in Journal of Labelled Compounds & Radiopharmaceuticals (2003), 46

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