References of "Lemaire, Christian"
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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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See detailEpimerization study on [18F]FDG produced by an alkaline hydrolysis on solid support under stringent conditions
Mosdzianowski, C.; Lemaire, Christian ULg; Simoens, F. et al

in Applied Radiation & Isotopes (2002), 56(6), 871-875

Since 1998, routine [18F]FDG syntheses are being carried out by alkaline hydrolysis on a solid support, i.e. the labeled intermediate is trapped on a tC18 solid phase extraction cartridge, purified and ... [more ▼]

Since 1998, routine [18F]FDG syntheses are being carried out by alkaline hydrolysis on a solid support, i.e. the labeled intermediate is trapped on a tC18 solid phase extraction cartridge, purified and finally hydrolyzed within the cartridge, at room temperature, using sodium hydroxide. The present study demonstrated that no epimerization of [18F]FDG to [18F]FDM occurs even when 12 N NaOH is used and when the hydrolysis time is extended up to 1 h. The alkaline hydrolysis on solid support appears to be a simple method leading to [18F]FDG with high purity. [less ▲]

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See detailInfluence of P-glycoprotein on the tissue distribution in rats of the 5-HT1A antagonist p-[18F]MPPF.
Plenevaux, Alain ULg; Lacan, G.; Defraiteur, C. et al

in Society for Neuroscience / Abstracts (2002)

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See detailFast F-18 FDG synthesis by alkaline hydrolysis on a low polarity solid phase supports
Lemaire, Christian ULg; Damhaut, P.; Lauricella, Benjamino ULg et al

in Journal of Labelled Compounds & Radiopharmaceuticals (2002), 45(5), 435-447

The synthesis of 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) has been simplified by the use of a tC18 Sep Pak cartridge to effect purification and hydrolysis of the tetraacetylated [18F]fluoro-glucose ... [more ▼]

The synthesis of 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) has been simplified by the use of a tC18 Sep Pak cartridge to effect purification and hydrolysis of the tetraacetylated [18F]fluoro-glucose compound ([18F]TAG). After radiolabelling, this derivative was trapped on a solid phase extraction (SPE) cartridge and the residual reaction solvent (CH3CN), reagents (K222, K2CO3,) and by-products removed by washing the support with water. After this cleaning step, the acetyl groups were cleaved on the same tC18 column using 2N sodium hydroxide. This fast reaction proceeded near quantitatively (>98%) at room temperature in less than 2 min. The [18F]FDG was then recovered with a small amount of water, neutralized with a slight excess of 2N hydrochloric acid, buffered for pH with a citrate solution and finally purified on a neutral alumina oxide and a second tC18 column. After filtration, the radiochemical yield of this [18F]FDG isotonic solution after more than 100 production runs was found to be very reliable and reproducible (70±6% decay corrected). The synthesis time was about 22 min. Quality controls showed that the radiochemical purity was higher than 98% and in any case no [18F]FDM was detected. Only traces of 2-chloro-2-deoxy-glucose (ClDG) were found in the final sample (64±9 g/ batch of 16 ml). [18F]FDG specific activity averaged between 1 and 20 Ci/µmol (EOS). No evaporation and use of ion retardation resin (AG11A8) are required. Moreover, this new approach is suitable for complete remote operation using available single use medical components. Copyright © 2002 John Wiley [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 detailEtudes par tomographie à émission de positons chez des patients en coma, en état végétatif ou de conscience minimale, en «locked-in syndrome» et en mort cérébrale
Laureys, Steven ULg; Faymonville, Marie-Elisabeth ULg; Berre, Jacques et al

in L'évaluation neurophysiologique des comas, de la mort encéphalique et des états végétatifs (2001)

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See detailEnantioselective synthesis of 2-[18F]fluoro-L-Tyrosine by catalytic phase-transfer alkylation.
Lemaire, Christian ULg; Gillet, S.; Ooi, T. et al

in Journal of Labelled Compounds & Radiopharmaceuticals (2001), 44

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See detailModeling p-18FMPPF pet kinetics for the detremination of local 5-HT1A receptor concentration.
Costes, N.; Le Bars, D.; Merlet, I. et al

in Journal of Nuclear Medicine : Official Publication, Society of Nuclear Medicine (2001), 42(S1), 209

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See detailVoxel-based distribution of metabolic impairment in corticobasal degeneration
Garraux, Gaëtan ULg; Salmon, Eric ULg; Peigneux, Philippe ULg et al

in Movement Disorders (2000), 15(5), 894-904

This report emphasizes the precise topographic distribution of cerebral metabolic impairment in corticobasal degeneration (CBD) and the pathophysiological differences between CBD and progressive ... [more ▼]

This report emphasizes the precise topographic distribution of cerebral metabolic impairment in corticobasal degeneration (CBD) and the pathophysiological differences between CBD and progressive supranuclear palsy (PSP). Statistical parametric mapping (SPM96) analysis of 18FDG positron emission tomography (PET) data was performed in 22 patients with CBD compared with 46 healthy subjects (HS) and 21 patients with PSP who were studied at rest. A statistical threshold of p <0.001 was fixed, further corrected for multiple or independent comparisons (p <0.05). In comparison with HS, the metabolic impairment in CBD was asymmetrically distributed in the putamen, thalamus, precentral (Brodmann's area, BA 4), lateral premotor (BA 6/44) and supplementary motor areas (SMA, BA 6), dorsolateral prefrontal (8/9/46) cortex, and the anterior part of the inferior parietal lobe (BA 40) including the intraparietal sulcus (BA 7/40). A similar hypometabolic pattern was observed for most individual analyses. When PSP was compared with CBD, metabolic impairment predominated in the midbrain, anterior cingulate (BA 24/32), and orbitofrontal regions (BA 10). The reverse contrast showed more posterior involvement in CBD (BA 6 and 5/7/40) including SMA. Our data suggest that multiple components of neural networks related to both movement execution and production of skilled movements are functionally disturbed in CBD compared with both HS and PSP. [less ▲]

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See detail[(18)F]p-MPPF: A radiolabeled antagonist for the study of 5-HT(1A) receptors with PET
Plenevaux, Alain ULg; Lemaire, Christian ULg; Aerts, Joël ULg et al

in Nuclear Medicine & Biology (2000), 27(5), 467-71

This paper summarizes the present status of the researches conducted with [(18)F]4-(2'-methoxyphenyl)-1-[2'-[N-(2"-pyridinyl)-p-fluorobenzamido ]ethyl]-piperazine known as [(18)F]p-MPPF, a new 5-HT(1A ... [more ▼]

This paper summarizes the present status of the researches conducted with [(18)F]4-(2'-methoxyphenyl)-1-[2'-[N-(2"-pyridinyl)-p-fluorobenzamido ]ethyl]-piperazine known as [(18)F]p-MPPF, a new 5-HT(1A) antagonist for the study of the serotonergic neurotransmission with positron emission tomography (PET). This includes chemistry, radiochemistry, animal data (rats, cats, and monkeys) with autoradiography and PET, human data with PET, toxicity, and metabolism. [less ▲]

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See detailSynthèse du 6-fluoro-a-méthyl-L-tryptophane et de ses principaux métabolites
Lambin, D.; Tadino, V.; Olynyk, Ch et al

Poster (2000, May 12)

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See detailVoxel-based analysis of confounding effects of age and dementia severity on cerebral metabolism in Alzheimer's disease
Salmon, Eric ULg; Collette, Fabienne ULg; Degueldre, Christian ULg et al

in Human brain mapping (2000), 10(1), 39-48

Alzheimer's disease is characterized by early hippocampal lesions, but neuropathological and functional imaging studies have also demonstrated involvement of associative cortices in patients suffering ... [more ▼]

Alzheimer's disease is characterized by early hippocampal lesions, but neuropathological and functional imaging studies have also demonstrated involvement of associative cortices in patients suffering from this illness. New image-processing technologies have led to demonstration of predominant posteromedial cortical metabolic impairment in the disease. Confounding effects of both age and dementia severity on brain metabolism were assessed using categorical and correlational analyses performed with Statistical Parametric Mapping. Posterior cingulate and precuneus metabolism, assessed by positron emission tomography, was significantly correlated with age in a population of 46 patients with probable Alzheimer's disease. Metabolism in posterior cingulate and precuneus was higher in elderly than in younger patients with a diagnosis of Alzheimer's disease, even when dementia severity was taken as a confounding covariate. The data suggest that the sensitivity of positron emission tomography for the diagnosis of Alzheimer's disease is reduced in elderly cases, where less severe pathology is sufficient to induce clinical symptoms of dementia. Conversely, higher posteromedial metabolic impairment in early onset cases may reflect greater density of regional cerebral lesions or major decrease of functional afferences in a richly connected multimodal associative area. Posterior cingulate metabolism was also correlated to dementia severity, even when age was taken as a confounding covariate, whereas metabolism in the hippocampal formation was not shown to correlate with global cognitive deficit. Functional correlation was maintained between posterior cingulate and middle frontal cortex in demented patients as in elderly controls. The key role of posteromedial cortex in cognitive dysfunction assessed in Alzheimer's disease is probably related to its highly integrated position within attentional, visuospatial and memory neuronal networks. [less ▲]

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See detailTissue distribution, autoradiography, and metabolism of 4-(2'-methoxyphenyl)-1-[2' -[N-2"-pyridinyl)-p-[(18)F]fluorobenzamido]ethyl]piperazine (p-[(18)F]MPPF), a new serotonin 5-HT(1A) antagonist for positron emission tomography: An In vivo study in rats.
Plenevaux, Alain ULg; Weissmann, D.; Aerts, Joël ULg et al

in Journal of Neurochemistry (2000), 75(2), 803-11

The in vivo behavior of 4-(2'-methoxyphenyl)-1-[2'-[N-(2"-pyridinyl)-p-[(18)F]fluorobenzamido ]ethyl]-piperazine (p-[(18)F]MPPF), a new serotonin 5-HT(1A) antagonist, was studied in awake, freely moving ... [more ▼]

The in vivo behavior of 4-(2'-methoxyphenyl)-1-[2'-[N-(2"-pyridinyl)-p-[(18)F]fluorobenzamido ]ethyl]-piperazine (p-[(18)F]MPPF), a new serotonin 5-HT(1A) antagonist, was studied in awake, freely moving rats. Biodistribution studies showed that the carbon-fluorine bond was stable in vivo, that this compound was able to cross the blood-brain barrier, and that a general diffusion equilibrium could account for the availability of the tracer. The great quantity of highly polar metabolites found in plasma did not contribute to the small amounts of metabolites found in hippocampus, frontal cortex, and cerebellum. Exvivo p-[(18)F]MPPF and in vitro 8-hydroxy-2-(di-n-[(3)H]propylamino)tetralin autoradiography were compared both qualitatively and quantitatively. Qualitative evaluation proved that the same brain regions were labeled and that the p-[(18)F]MPPF labeling is (a) in total agreement with the known distribution of 5-HT(1A) receptors in rats and (b) characterized by very low nonspecific binding. Quantitative comparison demonstrated that the in vivo labeling pattern obtained with p-[(18)F]MPPF cannot be explained by differences in regional blood flow, capillary density, or permeability. The 5-HT(1A) specificity of p-[(18)F]MPPF and binding reversibility were confirmed in vivo with displacement experiments. Thus, this compound can be used to evaluate parameters characterizing 5-HT(1A) binding sites in the brain. [less ▲]

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See detailMedial temporal lobe metabolic impairment in dementia associated with motor neuron disease
Garraux, Gaëtan ULg; Salmon, Eric ULg; Degueldre, Christian ULg et al

in Journal of the Neurological Sciences (1999), 168(2), 145-150

In the course of their disease certain patients with frontotemporal dementia (FTD) develop clinical features compatible with a motor neuron disease (FTD-MND). Previous reports have suggested that the ... [more ▼]

In the course of their disease certain patients with frontotemporal dementia (FTD) develop clinical features compatible with a motor neuron disease (FTD-MND). Previous reports have suggested that the functional pattern is similar in FTD and FTD-MND. However, some neuropathological studies suggest greater involvement of medial temporal regions in FTD-MND than in FTD. Using statistical parametric mapping (SPM96), we compared the metabolic patterns obtained at rest with positron emission tomography in 10 FTD patients and three FTD-MND patients with those obtained from 46 healthy subjects (HS). Mean age, duration of illness and dementia stage did not differ statistically between the FTD and FTD-MND groups. In comparison with HS, both groups showed frontal and anterior temporal hypometabolism at P<0.001. When the FTD-MND group was compared to the FTD group, significant hypometabolism was only observed in bilateral amygdala, bilateral hippocampus, and bilateral enthorinal and parahippocampal regions (Brodmann's areas, BA 28/36) at P<0.005. We found no significant differences in regional glucose uptake when FTD patients were contrasted to FTD-MND patients. Our results suggest statistically comparable frontal and lateral temporal hypometabolism in both conditions but greater impairment of medial temporal lobe activity in FTD-MND. Our results and a review of the literature support the hypothesis that there is a functional continuum between classical motor neuron disease (cMND), FTD-MND, and FTD. [less ▲]

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See detailComparison of impaired subcortico-frontal metabolic networks in normal aging, subcortico-frontal dementia, and cortical frontal demential
Garraux, Gaëtan ULg; Salmon, Eric ULg; Degueldre, Christian ULg et al

in Neuroimage (1999), 10(2), 149-162

Normal aging, progressive supranuclear palsy (PSP), and frontotemporal dementia (FTD) are characterized by different degrees of decline in frontal lobe functions. We used (18)FDG-PET and statistical ... [more ▼]

Normal aging, progressive supranuclear palsy (PSP), and frontotemporal dementia (FTD) are characterized by different degrees of decline in frontal lobe functions. We used (18)FDG-PET and statistical parametric mapping (SPM96) to compare relative subcorticofrontal metabolic impairment at rest in 21 healthy elderly subjects (HES), 20 PSP patients, and 6 FTD patients. When HES were compared to 22 healthy young subjects, widespread decrease in metabolism was observed in bilateral medial prefrontal areas including anterior cingulate cortices, in dorsolateral prefrontal areas, in left lateral premotor area, in Broca's area, and in left insula. In PSP compared to the 43 healthy subjects (HS), we observed subcorticofrontal metabolic impairment including both motor and cognitive neural networks. Impairment of functional connections between midbrain tegmentum and cerebellar, temporal and pallidal regions was demonstrated in PSP as compared to HS. When comparing FTD to HS, glucose uptake was primarily reduced in dorsolateral and ventrolateral prefrontal cortices and in frontopolar and anterior cingulate regions. There was also bilateral anterior temporal, right inferior parietal, and bilateral striatal hypometabolism. Finally, FTD showed more severe striatofrontal metabolic impairment than PSP, while mesencephalothalamic involvement was only observed in PSP. Our data suggest that subcorticofrontal metabolic impairment is distributed in distinct subcorticocortical networks in normal aging, PSP, and FTD. Subcorticofrontal dementia in PSP is related to hypometabolism in discrete frontal areas, which are probably disconnected from certain subcortical structures. The concept of subcortical dementia is reinforced by our data, which show disrupted functional connections between mesencephalon and cerebellar cortex, inferior and medial temporal regions, and pallidum. [less ▲]

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See detailSynthèse du 6-fluoro-a-méthyl-L-tryptophane et d'un de ses métabolites
Lambin, D.; Tadino, V.; Olynyk, Ch et al

Poster (1999, May 03)

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See detailFluorodopa uptake and glucose metabolism in early stages of corticobasal degeneration.
Laureys, Steven ULg; Salmon, Eric ULg; Garraux, Gaëtan ULg et al

in Journal of Neurology (1999), 246(12), 1151-8

Fluorodopa (FDOPA) and fluorodeoxyglucose (FDG) PET was performed in six patients in early stages of corticobasal degeneration (CBD) and compared to Parkinson's disease (PD) patients with a similar degree ... [more ▼]

Fluorodopa (FDOPA) and fluorodeoxyglucose (FDG) PET was performed in six patients in early stages of corticobasal degeneration (CBD) and compared to Parkinson's disease (PD) patients with a similar degree of bradykinesia and rigidity and to healthy controls. Statistical parametric mapping analysis comparing CBD to controls showed metabolic decrease in premotor, primary motor, supplementary motor, primary sensory, prefrontal, and parietal associative cortices, and in caudate and thalamus contralateral to the side of clinical signs. Except for the prefrontal regions a similar metabolic pattern was observed when CBD was compared to PD. Putamen FDOPA uptake was decreased in both CBD and PD. Caudate FDOPA uptake in CBD patients was decreased contralateral to clinical signs when compared to controls, but was higher than in PD. In early stages of CBD, FDOPA and FDG PET patterns differed from those observed in PD. In CBD the asymmetry in FDOPA uptake was less pronounced than that of clinical signs or metabolic impairment. [less ▲]

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See detailCerebral metabolism during vegetative state and after recovery to consciousness
Laureys, Steven ULg; Lemaire, Christian ULg; Maquet, Pierre ULg et al

in Journal of Neurology, Neurosurgery & Psychiatry (1999), 67(1), 121-122

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See detail5-HT1A Receptors visualization with p-[18F]MPPF in healthy volunteers.
Plenevaux, Alain ULg; Lemaire, Christian ULg; Salmon, Eric ULg et al

in Journal of Labelled Compounds & Radiopharmaceuticals (1999), 42

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See detailp-[18F]MPPF, a fluoro analog of WAY-100635 for visualisation of 5-HT1A receptors in cat.
Le Bars, D.; Ginovart, N.; Hassoun, W. et al

in Journal of Labelled Compounds & Radiopharmaceuticals (1999), 42

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