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See detailS-, N- and O-[11C]methylations of a Nor precursor adsorbed on Al2O3/KF.
Schmitz, F.; Plenevaux, Alain ULg; Del Fiore, G. et al

in Journal of Labelled Compounds & Radiopharmaceuticals (1995), 37

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See detail[1-11C]Bromoethane: an alternative to the use of [1-11C]iodoethane.
Schmitz, F.; Del Fiore, G.; Plenevaux, Alain ULg et al

in Journal of Labelled Compounds & Radiopharmaceuticals (1995), 37

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See detailFast quality control of short-lived radiopharmaceutical compounds with a photodiode array detector.
Plenevaux, Alain ULg; Lemaire, Christian ULg; Aerts, Joël ULg et al

in Journal of Labelled Compounds & Radiopharmaceuticals (1995), 37

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See detailFast routine production of L-[11C-methyl]methionine with Al2O3/KF in a disposable unit.
Del Fiore, G.; Schmitz, F.; Plenevaux, Alain ULg et al

in Journal of Labelled Compounds & Radiopharmaceuticals (1995), 37

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See detailSep Pak as alternative to rotary evaporators for radiopharmaceutical formulations.
Lemaire, Christian ULg; Plenevaux, Alain ULg; Del Fiore, G. et al

in Journal of Labelled Compounds & Radiopharmaceuticals (1995), 37

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See detailFast Routine Production of L-[11C-methyl]methionine with Al2O3KF
Schmitz, Frédéric; Plenevaux, Alain ULg; Del-Fiore, Guy et al

in Applied Radiation & Isotopes (1995), 46(9), 893-897

No-carrier-added (nca) L-[11C-methyl]methionine was prepared via the very fast S-alkylation of L-homocysteine adsorbed on AI203/KF with [11C]iodomethane at room temperature in ethanol. The alkylation was ... [more ▼]

No-carrier-added (nca) L-[11C-methyl]methionine was prepared via the very fast S-alkylation of L-homocysteine adsorbed on AI203/KF with [11C]iodomethane at room temperature in ethanol. The alkylation was realized with a radiochemical yield of 94 +/- 4% EOB (n = 20). More than 90% (n = 20) of the precursor L-homocysteine remained adsorbed on the solid support and was eliminated by a simple filtration. After reaction, neither racemization nor by-product were detected. The purification process was thus limited to a C18 Sep-Pak followed by an alumina Sep-Pak. The radiochemical purity measured on the final solution was shown to be > 99%. The only chemical contaminant was L-homocysteine (+ 10 µg). With this new technique, L-[11C-methyl]methionine was ready for injection within 10 min from [11C]CO2 with a specific activity ranging around 37 + 5.6 GBq (1 +/- 0.15 Ci)//tmol EOB. Through this procedure L-[11C-methyl]methionine can be prepared without preparative HPLC purification, This is an important simplification for the fast routine production of one of the most widely used radiopharmaceutical compounds for PET. [less ▲]

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See detailSerotonin 5HT2 receptor imaging in the human brain using positron emission tomography and a new radioligand, [18F]altanserin: results in young normal controls.
Sadzot, Bernard ULg; Lemaire, Christian ULg; Maquet, Pierre ULg et al

in Journal of Cerebral Blood Flow & Metabolism (1995), 15(5), 787-97

Changes in serotonin-2 receptors have been demonstrated in brain autopsy material from patients with various neurodegenerative and affective disorders. It would be desirable to locate a ligand for the ... [more ▼]

Changes in serotonin-2 receptors have been demonstrated in brain autopsy material from patients with various neurodegenerative and affective disorders. It would be desirable to locate a ligand for the study of these receptors in vivo with positron emission tomography (PET). Altanserin is a 4-benzoylpiperidine derivative with a high affinity and selectivity for S2 receptors in vitro. Dynamic PET studies were carried out in nine normal volunteers with high-specific activity (376-1,680 mCi/mumol) [18F]altanserin. Arterial blood samples were obtained and the plasma time-activity curves were corrected for the presence of labeled metabolites. Thirty minutes after injection, selective retention of the radioligand was observed in cortical areas, while the cerebellum, caudate, and thalamus had low radioactivity levels. Specific binding reached a plateau between 30 and 65 min postinjection at 1.8% of the injected dose/L of brain and then decreased, indicating the reversibility of the binding. The total/nonspecific binding ratio reached 2.6 for times between 50 and 70 min postinjection. The graphical analysis proposed by Logan et al. allowed us to estimate the binding potential (Bmax/KD). Pretreatment with ketanserin was given to three volunteers and brain activity remained uniformly low. An additional study in one volunteer showed that [18F]altanserin can be displaced from the receptors by large doses of ketanserin. At the end of the study, unchanged altanserin was 57% of the total plasma activity. These results suggest that [18F]altanserin is selective for S2 receptors in vivo as it is in vitro. They indicate that [18F]altanserin is suitable for imaging and quantifying S2 receptors with PET in humans. [less ▲]

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See detailDifferential diagnosis of Alzheimer's disease with PET.
Salmon, Eric ULg; Sadzot, Bernard ULg; Maquet, Pierre ULg et al

in Journal of Nuclear Medicine : Official Publication, Society of Nuclear Medicine (1994), 35(3), 391-8

PET studies have demonstrated bilateral temporo-parietal hypoperfusion and hypometabolism in probable and definite Alzheimer's disease (AD), a pattern that may help differentiate AD from other dementias ... [more ▼]

PET studies have demonstrated bilateral temporo-parietal hypoperfusion and hypometabolism in probable and definite Alzheimer's disease (AD), a pattern that may help differentiate AD from other dementias. METHODS: To evaluate the diagnostic power of cerebral metabolic distribution patterns for "cortical" degenerative dementias, PET scans obtained from 129 patients referred for differential diagnosis of dementia were analyzed visually. RESULTS: Sixty-five patients had a final clinical diagnosis of probable AD. Ninety-seven percent (97%) of those had abnormal metabolic scans and 94% showed a suggestive pattern of bilateral or unilateral temporo-parietal hypometabolism (with or without frontal involvement). Hypometabolism was unilateral in 23% of patients. Five subjects with a neuropathologically proven diagnosis of Alzheimer's disease had a suggestive metabolic pattern. One of those was an early case with frontal hypometabolism exceeding temporo-parietal involvement. Two patients with Alzheimer's-type dementia had isolated bilateral frontal hypometabolism. CONCLUSIONS: This alternative metabolic pattern may correspond to a non-Alzheimer pathology occurring in 10%-20% of patients suffering from clinically probable Alzheimer's disease. Most of the patients with possible but atypical Alzheimer's-type dementia showed isolated bilateral frontal involvement. This metabolic pattern probably corresponds to different diseases, such as Pick's disease, frontal lobe dementia or progressive subcortical gliosis. [less ▲]

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See detailEnantioselective syntheses of n.c.a. L-(a-methyl)-[b-11C]-4-chlorophenylalanine and L-(a-[11C]methyl-tryptophan.
Plenevaux, Alain ULg; Al-Darwich, M. J.; Lemaire, Christian ULg et al

in Journal of Labelled Compounds & Radiopharmaceuticals (1994), 35

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See detailN.C.A. asymmetric syntheses of a-methyl and b-hydroxy a-amino acid labelled with fluorine-18 for probing enzymatic function.
Damhaut, Ph.; Lemaire, Christian ULg; Plenevaux, Alain ULg et al

in Journal of Labelled Compounds & Radiopharmaceuticals (1994), 35

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See detail11C-alkylation on Al2O3/MF: a useful method for rapid labelling.
Schmitz, F.; Plenevaux, Alain ULg; Del Fiore, G. et al

in Journal of Labelled Compounds & Radiopharmaceuticals (1994), 35

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See detailRobot-assisted synthesis of [18F]altanserin, 4-[18F]fluorotropapride, 6-[18F]fluoro-L-dopa and 2-[18F]fluoro-L-tyrosine.
Brihaye, C.; Lemaire, Christian ULg; Damhaut, Ph. et al

in Journal of Labelled Compounds & Radiopharmaceuticals (1994), 35

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See detailEnantioselective synhteses of n.c.a. L-2-[18F]fluoro-4-chlorophenylalanine and of L-(a-methyl)-2-[18F]fluoro-4-chlorophenylalanine.
Al-Darwich, M. J.; Plenevaux, Alain ULg; Lemaire, Christian ULg et al

in Journal of Nuclear Medicine : Official Publication, Society of Nuclear Medicine (1994), 35

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See detailAl2O3/KF in radiochemistry: fast preparation of L-[11C-methyl]methionine without HPLC.
Schmitz, F.; Plenevaux, Alain ULg; Del Fiore, G. et al

in Journal of Nuclear Medicine : Official Publication, Society of Nuclear Medicine (1994), 35

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See detailENANTIOSELECTIVE SYNTHESES OF NCA (S)-L-[BETA-C-11]-4-CHLOROPHENYLALANINE AND (S)-L-(ALPHA-METHYL)-[BETA-C-11]-4-CHLOROPHENYLALANINE
Plenevaux, Alain ULg; Al-Darwich, M. J.; Lemaire, Christian ULg et al

in Applied Radiation & Isotopes (1994), 45(3), 361-369

The radiolabeling of (S)-L-4-chlorophenylalanine and (S)-L-(alpha-methyl)-4-chlorophenylalanine were realized with carbon-11 at position beta through a radiochemical synthesis relying on the highly ... [more ▼]

The radiolabeling of (S)-L-4-chlorophenylalanine and (S)-L-(alpha-methyl)-4-chlorophenylalanine were realized with carbon-11 at position beta through a radiochemical synthesis relying on the highly enantioselective reaction between 4-chloro[alpha-C-11]benzyl bromide and the lithium enolate of (S)-1-(t-butyloxycarbonyl)-2-(t-butyl)-3-methyl-1,3-imidazolidine-4-one for (S)-L-[beta-C-11]-4-chlorophenylalanine and of (2S,5S)-1-(t-butyloxycarbonyl)-2-(t-butyl)-3,5-dimethyl-1,3-imidazolidin e-4-one for (S)-L-(alpha-methyl)-[beta-C-11]-4-chlorophenylalanine. Quantities of about 25-35 mCi were obtained at the end of synthesis, ready for injection, after hydrolysis and HPLC purification with a radiochemical yield of 19% corrected to EOB within 45 min. The enantiomeric excesses were shown to be greater than or equal to 97% for both molecules without chiral separation. The radiochemical and the chemical purities of the final compounds were greater than or equal to 98% and the specific activity at the end of synthesis ranged between 250-800 mCi/mu mol. [less ▲]

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See detailENANTIOSELECTIVE SYNTHESIS OF NCA (S)-L-([ALPHA-C-11]METHYL)-TRYPTOPHAN
Plenevaux, Alain ULg; Lemaire, Christian ULg; Delfiore, Guy et al

in Applied Radiation & Isotopes (1994), 45(6), 651-653

N.c.a. (S)-L-([alpha-C-11]methyl)-tryptophan was prepared by treatment at -78-degrees-C of (2S,3aR,8aS)-1,2-bis(-methoxycarbonyl)-1,2,3,3a,8,8a-hexahydropyrrolo[2, 3-b]-indole with lithium ... [more ▼]

N.c.a. (S)-L-([alpha-C-11]methyl)-tryptophan was prepared by treatment at -78-degrees-C of (2S,3aR,8aS)-1,2-bis(-methoxycarbonyl)-1,2,3,3a,8,8a-hexahydropyrrolo[2, 3-b]-indole with lithium diisopropylamide and [C-11]CH3I. After hydrolysis with HI and HPLC purification, the title compound was isolated with a radiochemical yield of 36% (EOB corrected) within 22 min; e.e. was shown > 97% (n = 20); specific activity was ranging between 0.8 and 1.2 Ci (30-45 GBq)/mu mol EOB. [less ▲]

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See detailEnantioselective synthesis of 6-[fluorine-18]-fluoro-L-dopa from no-carrier-added fluorine-18-fluoride.
Lemaire, Christian ULg; Damhaut, Philippe; Plenevaux, Alain ULg et al

in Journal of Nuclear Medicine : Official Publication, Society of Nuclear Medicine (1994), 35(12), 1996-2002

METHODS: A trimethylammonium veratraldehyde triflate was synthesized and used as a precursor for the asymmetric synthesis of 6-[18F]fluoro-L-dopa. RESULTS: Its nucleophilic fluorination with 18F-fluoride ... [more ▼]

METHODS: A trimethylammonium veratraldehyde triflate was synthesized and used as a precursor for the asymmetric synthesis of 6-[18F]fluoro-L-dopa. RESULTS: Its nucleophilic fluorination with 18F-fluoride produced by the 18O(p,n)18F nuclear reaction on enriched 18O-water led to the corresponding no-carrier-added [18F]fluoroveratraldehyde (45 +/- 5% EOB). Diiodosilane was used to prepare the corresponding [18F]fluorobenzyl iodide (36.5 +/- 5.3% EOB). Akylation of (S)-1-tert-boc-2-tert-butyl-3-methyl-4-imidazolidinone with this electrophilic agent, hydrolysis and purification by preparative high-pressure liquid chromatography made 6-[18F]fluoro-L-dopa ready for human injection, in a 23% +/- 6% decay-corrected radiochemical yield. The enantiomeric purity and the specific activity were above 96% and 1 Ci/mumole respectively. CONCLUSION: Through this procedure, starting from 250 mCi of 18F-fluoride, multimillicurie amounts (32 +/- 8.5 mCi) of no-carrier-added 6-[18F]fluoro-L-dopa are now available at the end of synthesis (90 min) with a good radiochemical purity (more than 98%). [less ▲]

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See detailSynthesis and biodistribution of [5-131I]iodotropapride: a potential D2 dopamine receptor imaging agent.
Cantineau, Robert; Guillaume, Marcel; Damhaut, Philippe et al

in Nuclear Medicine & Biology (1994), 21(2), 255-62

[5-131I]Iodotropapride is a benzamidic compound which displays high affinity and selectivity for dopaminergic receptors. It was prepared from the corresponding brominated compound by a nucleophilic ... [more ▼]

[5-131I]Iodotropapride is a benzamidic compound which displays high affinity and selectivity for dopaminergic receptors. It was prepared from the corresponding brominated compound by a nucleophilic substitution with [131I]iodine (t1/2 = 8.02 days, E gamma = 364 keV) based on the use of Cu(I) as catalyst and high specific activity of [131I]NaI. After i.v. injection in rats the tracer crosses the blood-brain barrier (0.42 +/- 0.06% of injected dose in the total brain) and demonstrates a high affinity binding to the striatum. The striatum-to-cerebellum ratio increases with time and reaches values of 9 and 22 at 30 and 120 min after injection, respectively. This specific uptake in the striatum is saturable and can be blocked by pretreatment with different D2 antagonists. When labeled with 123I (t1/2 = 13 h, E1 = 159 keV), the corresponding [123I]iodotropapride may be useful for the investigation of the D2 dopamine receptors in humans with single photon emission computer tomography (SPECT). [less ▲]

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