References of "Lemaire, Christian"
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See detailRadiochemistry automation for PET
Crouzel, Christian; Clark, John; Brihaye, Claude et al

in Stöcklin, G; Pike, V (Eds.) Radiopharmaceuticals for Positron Emission Tomography (1993)

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See detailProduction of L-[18F]fluoroamino acids for protein synthesis: overview and recent developments in nucleophilic synthesis
Lemaire, Christian ULg

in PET studies on Amino Acid Metabolism and Protein Synthesis (1993)

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See detailNCA asymmetric synthesis of 2-[18F]fluoro-L-tyrosine.
Lemaire, Christian ULg; Plenevaux, Alain ULg; Damhaut, Ph. et al

in Journal of Labelled Compounds & Radiopharmaceuticals (1993), 32

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See detailAsymmetric synthesis of n.c.a. L-[2-11C]-4-chlorophenylalanine.
Plenevaux, Alain ULg; Al-Darwich, M. J.; Lemaire, Christian ULg et al

in Journal of Labelled Compounds & Radiopharmaceuticals (1993), 32

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See detailNon-activated 18F-fluorinated aromatic compounds through nucleophilic substitution and decarbonylation reactions using RhCl[P(C6H5)3]3.
Plenevaux, Alain ULg; Lemaire, Christian ULg; Palmer, A. J. et al

in Journal of Labelled Compounds & Radiopharmaceuticals (1993), 32

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See detailNUCLEOPHILIC ENANTIOSELECTIVE SYNTHESIS OF 6-[F-18]FLUORO-L-DOPA VIA 2 CHIRAL AUXILIARIES
Lemaire, Christian ULg; Plenevaux, Alain ULg; Cantineau, Robert et al

in Applied Radiation & Isotopes (1993), 44(4), 737-744

Asymmetric nucleophilic synthesis of 6-[F-18]fluoro-L-dopa was investigated in order to reach an enantiomeric excess of close to 100% of the L form of this amino acid. The radiochemical synthesis required ... [more ▼]

Asymmetric nucleophilic synthesis of 6-[F-18]fluoro-L-dopa was investigated in order to reach an enantiomeric excess of close to 100% of the L form of this amino acid. The radiochemical synthesis required [F-18]fluoride as fluorinating agent and regioselective nucleophilic substitution of commercially available 6-nitroveratraldehyde. The [F-18]fluorobenzaldehyde thus obtained was easily converted to the corresponding 2-[F-18]fluoro-4,5-dimethoxybenzyl bromide. This alkylating agent was added to the lithium enolates of 1-(S)-(-)camphor imine of t-butyl glycinate (1) and (S)-(-)- 1 -Boc-2-t-butyl-3-methyl-4-imidazolidinone [(S)- Boc-BMI] (2) in order to compare the enantiomeric excess of the L form obtained in each case with these two chiral inductors. The L-isomer of fluorodopa was isolated after H1 hydrolysis and HPLC purification in 5-10% radiochemical yield (decay corrected). The overall synthesis time was of 110 min. Through this synthetic pathway, the L-isomer of fluorodopa was obtained in 83% e.e with 1 and 96% e.e with 2 respectively, as determined by chiral HPLC. A practical three step preparative scale synthesis of 6-[F-19]fluoro-D,L-dopa is also presented. [less ▲]

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See detailSYNTHESIS OF F-18 SUBSTITUTED AROMATIC-ALDEHYDES AND BENZYL BROMIDES, NEW INTERMEDIATES FOR NCA [F-18] FLUORINATION
Lemaire, Christian ULg; Damhaut, Philippe; Plenevaux, Alain ULg et al

in Applied Radiation & Isotopes (1992), 43(4), 485-494

The synthesis of various [F-18]fluoroaromatic aldehydes using activated nitro precursors and aminopolyether supported nucleophilic substitution with F-18(-) is reported. These radiolabelled fluorinated ... [more ▼]

The synthesis of various [F-18]fluoroaromatic aldehydes using activated nitro precursors and aminopolyether supported nucleophilic substitution with F-18(-) is reported. These radiolabelled fluorinated aldehydes (radiochemical yields: 50-75%) are powerful key intermediates leading after treatment with NaBH4 and SOBr2 (SOCl2) to further active intermediates for example substituted [F-18]fluorobenzyl bromides (yields 30-50% EOB). These benzaldehydes and bromides are particularly useful for the preparation of new radiopharmaceuticals (e.g. fluorotroprapride, fluorodexetimide) either by reductive amination or by aromatic N-alkylation. The preparation of various amino acids in D, L (50:50) or enriched L form by asymmetric synthesis is also possible (e.g. L-6-[F-18]fluorodopa, L-4-[F-18]fluoro-m-tyrosine). It can be anticipated that the F-18-labelled fluoroaldehydes will find widespread application in radiopharmaceutical chemistry. [less ▲]

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See detailLigands and tracers for PET studies of the 5-HT system--current status.
Crouzel, C.; Guillaume, Marcel ULg; Barre, L. et al

in International Journal of Radiation Applications and Instrumentation. Part B : Nuclear Medicine and Biology (1992), 19(8), 857-70

The status of the radiochemical development and biological evaluation of radioligands and tracers for PET studies of the serotonergic system is reviewed, indicating those agents with present value and ... [more ▼]

The status of the radiochemical development and biological evaluation of radioligands and tracers for PET studies of the serotonergic system is reviewed, indicating those agents with present value and those with future potential. Practical recommendations are given for the preparation of two useful radioligands for PET studies of central 5-HT2 receptors, namely [18F]setoperone and [18F]altanserin. Though, it has not proved possible to recommend tracers or radioligands for the study of other aspects of serotonergic system, prospects for future radiochemical development are indicated, especially for developing radioligands for the 5-HT re-uptake site, and for the 5-HT1 and 5-HT3 receptors. [less ▲]

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See detailAmino acids for the measurement of protein synthesis in vivo by PET.
Vaalburg, W.; Coenen, H. H.; Crouzel, C. et al

in International Journal of Radiation Applications and Instrumentation. Part B : Nuclear Medicine and Biology (1992), 19(2), 227-37

In principle, PET in combination with amino acids labelled with positron-emitting radionuclides and kinetic metabolic models, can quantify local protein synthesis rates in tissue in vivo. These PET ... [more ▼]

In principle, PET in combination with amino acids labelled with positron-emitting radionuclides and kinetic metabolic models, can quantify local protein synthesis rates in tissue in vivo. These PET measurements have clinical potential in, for example, oncology, neurology and psychiatry. An optimal positron-emitting amino acid for the measurement of PSR has a high protein incorporation, can easily be prepared by automated equipment and has minimal non-protein radioactive metabolites. Presently L-[methyl-11C]methionine, L-[1-11C]leucine, L-[1-11C]tyrosine, L-[1-11C]phenylalanine, L-[1-11C]methionine and L-[2-18F]fluorotyrosine are under evaluation in normal volunteers and/or in patients. Several other amino acids are suggested. No comparison of the clinical usefulness of the different amino acids in man is yet available. Because of the longer half life of 18F compared to 11C, [18F]fluoro amino acids may have advantages over [11C]amino acids for the investigation of tissue with relative slow protein synthesis, such as brain, and for application in institutions with an off site, but nearby cyclotron. The half life of [13N]amino acids is considered to be too short for flexible clinical application. As yet no metabolic compartmental model has been investigated for [13N]amino acids. For routine application reliable preparation of the radiopharmaceutical is essential. Of all the amino acids under evaluation, a reliable, high yield, easy to automate production procedure is available for L-[methyl-11C]methionine only. It is however unlikely that this tracer can accurately measure PSR because of its non-protein metabolism. For the other amino acids the main problems in production are associated with complex multistep syntheses and/or low radiochemical yields, complex purification methods and the need to isolate the L-enantiomer. The kinetic metabolic models under investigation, consist of 4 or 5 compartments depending on the necessity to compensate for labelled metabolites. The metabolic profile of the amino acids is mainly extracted from animal experiments. Because of the number and amount of labelled metabolites in plasma, [11C]carboxylic labelled amino acids are preferred to amino acids with carbon-11 in another position. As yet no recommendation can be given on the optimal labelled amino acid(s) for PSR measurement in vivo nor on the methods to prepare the amino acids reported for this purpose. [less ▲]

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See detailFeasibility of multumillicurie preparation of L-6-[18F]fluorodopa by nucleophilic asymmetric synthesis.
Lemaire, Christian ULg; Plenevaux, Alain ULg; Comar, D.

in European Journal of Nuclear Medicine (1992), 19

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See detailSYNTHESIS OF NONACTIVATED F-18 FLUORINATED AROMATIC-COMPOUNDS THROUGH NUCLEOPHILIC-SUBSTITUTION AND DECARBOXYLATION REACTIONS
Plenevaux, Alain ULg; Lemaire, Christian ULg; Palmer, Anthtony J. et al

in Applied Radiation & Isotopes (1992), 43(8), 1035-1040

The synthesis of no-carrier-added 3-[F-18]fluoroanisole, 2-[F-18]fluoroanisole, [F-18]fluorobenzene and 4-[F-18]fluoroveratrole are reported. The strategy consists of amino-polyether supported ... [more ▼]

The synthesis of no-carrier-added 3-[F-18]fluoroanisole, 2-[F-18]fluoroanisole, [F-18]fluorobenzene and 4-[F-18]fluoroveratrole are reported. The strategy consists of amino-polyether supported nucleophilic substitution with [F-18]F- on activated nitro aromatic aldehyde precursors followed by decarbonylation using Tris(triphenylphosphine) rhodium (I) chloride. The experimental parameters for this reaction have been studied and optimized with 2-[F-18]fluoro-4-methoxybenzaldehyde and then successfully applied to four other F-18-fluorinated aromatic aldehydes. The decarbonylation yields obtained were 84 +/- 5% (corrected for decay) within 15 min at 150-degrees-C in 1,4-dioxan. [less ▲]

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See detail2- and 4-[18F]fluorotropapride, two specific D2 receptor ligands for positron emission tomography: N.C.A. syntheses and animal studies.
Damhaut, Philippe; Cantineau, Robert; Lemaire, Christian ULg et al

in International Journal of Radiation Applications and Instrumentation. Part A : Applied Radiation and Isotopes (1992), 43(10), 1265-74

Tropapride, (exo)-2,3-dimethoxy-N-[8-(phenylmethyl)-8- azabicyclo[3.2.1]oct-3-yl]benzamide hydrochloride, has been labeled with fluorine-18 at the 2- and 4-positions of its benzylic group. Two synthetic ... [more ▼]

Tropapride, (exo)-2,3-dimethoxy-N-[8-(phenylmethyl)-8- azabicyclo[3.2.1]oct-3-yl]benzamide hydrochloride, has been labeled with fluorine-18 at the 2- and 4-positions of its benzylic group. Two synthetic pathways were investigated: the first one required the alkylation of the norbenzyl precursor with 2- or 4-[18F]fluorobenzyl bromide (radiochemical yield of 5% EOB, 180 min); the second method consisted of a reductive amination of norbenzyl tropapride with 2- or 4-[18F]fluorobenzaldehyde (20% EOB, 110 min). In both cases, the specific activity was found to be greater than 1 Ci/mumol (EOS). Animal studies in rats showed the percentage of the injected dose localizing in the whole brain to be 0.6 +/- 0.09 and 0.2 +/- 0.03 at 2 h post injection for the para- and the ortho-[18F]fluoro analogs of tropapride respectively. Cerebral biodistribution studies showed at 4 h a striatum uptake of 5 +/- 0.7% of the injected dose per gram of striatum for the para derivative with a low fixation into the frontal cortex and the cerebellum (% ID/g FC < 0.4 and % ID/g Cb < 0.3). The selectivity of 4-[18F]fluorotropapride for D2 dopaminergic sites was demonstrated through blocking experiments with ketanserin, spiperone and halopemide. The saturability was confirmed by the use of variable specific activities. These preliminary results showed that 4-[18F]fluorotropapride can be considered as a potent radiopharmaceutical for the study of the dopaminergic system with PET. [less ▲]

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See detailDecrease of frontal metabolism demonstrated by positron emission tomography in a population of healthy elderly volunteers.
Salmon, Eric ULg; Maquet, Pierre ULg; Sadzot, Bernard ULg et al

in Acta Neurologica Belgica (1991), 91(5), 288-95

Frontal metabolism measured with positron emission tomography is shown to be decreased relatively to that in other cortical or sub-cortical areas, in a population of healthy elderly compared to young ... [more ▼]

Frontal metabolism measured with positron emission tomography is shown to be decreased relatively to that in other cortical or sub-cortical areas, in a population of healthy elderly compared to young volunteers. Cortical atrophy or neuronal depopulation are unlikely to entirely explain this physiological phenomenon, and sub-cortico-cortical deactivation should play a role, analogous to that proposed in subcortical diseases. [less ▲]

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See detailChemical processing for the production of carrier free selenium-73 from germanium and arsenic targets and synthesis of L-[73Se]selenomethionine.
Plenevaux, Alain ULg; Guillaume, M.; Brihaye, C. et al

in Journal of Labelled Compounds & Radiopharmaceuticals (1991), 30

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See detailNCA synthesis of an N-w-[18F]fluoroethyl analog of altanserine, a serotonine S2 receptor ligand.
Lemaire, Christian ULg; Damhaut, Ph.; Cantineau, R. et al

in Journal of Labelled Compounds & Radiopharmaceuticals (1991), 30

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See detailRoutine production and improvement in the purification of 3-N-(2'-[18F]fluoroethyl)spiperone for clinical use.
Plenevaux, Alain ULg; Cantineau, R.; Labar, D. et al

in Journal of Labelled Compounds & Radiopharmaceuticals (1991), 30

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See detailNCA asymmetric synthesis of 6-[18F]fluoro-L-dopa.
Lemaire, Christian ULg; Guillaume, M.; Cantineau, R. et al

in Journal of Labelled Compounds & Radiopharmaceuticals (1991), 30

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See detail18F-substituted aromatic aldehydes, key intermediates for nca radiosyntheses.
Lemaire, Christian ULg; Guillaume, M.; Plenevaux, Alain ULg et al

in Journal of Labelled Compounds & Radiopharmaceuticals (1991), 30

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See detailSynthesis and preliminary animal studies of [131I]iodotropapride: a cerebral dopamine D2 receptor ligand.
Cantineau, R.; Damhaut, Ph.; Plenevaux, Alain ULg et al

in Journal of Labelled Compounds & Radiopharmaceuticals (1991), 30

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See detailAsymmetric synthesis of 4-[18F]fluoro-L-m-tyrosine via aromatic fluorination.
Lemaire, Christian ULg; Damhaut, Ph.; Plenevaux, Alain ULg et al

in Journal of Nuclear Medicine : Official Publication, Society of Nuclear Medicine (1991), 32

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