![]() Microwave improved synthesis of p-[18F]MPPF, 5-HT1A antagonist and PET sudies on cat brain.; ; Lemaire, Christian et alin Journal of Labelled Compounds & Radiopharmaceuticals (1997), 40 Detailed reference viewed: 6 (0 ULg)![]() Synthesis of a fluorinated analogue of L-threo-3-(3,4-dihydroxyphenyl)serine: 6-fluoro-L-threo-DOPS.; Lemaire, Christian ; Plenevaux, Alain et alin Journal of Labelled Compounds & Radiopharmaceuticals (1997), 40 Detailed reference viewed: 2 (1 ULg)![]() Synthesis of [18F]FDG with alkaline hydrolysis on a low polarity solid phase support.Lemaire, Christian ; ; Lauricella, Benjamino et alin Journal of Labelled Compounds & Radiopharmaceuticals (1997), 40 Detailed reference viewed: 16 (4 ULg)![]() Metabolism of no carrier added 2-[18F]fluoro-L-tyrosine in free moving rats.Aerts, Joël ; Plenevaux, Alain ; Lemaire, Christian et alin Journal of Labelled Compounds & Radiopharmaceuticals (1997), 40 Detailed reference viewed: 3 (0 ULg)![]() Tissue distribution, autoradiography and metabolism in rats of p-[18F]MPPF: 5-HT1A antagonist.Plenevaux, Alain ; Aerts, Joël ; Lemaire, Christian et alin Journal of Labelled Compounds & Radiopharmaceuticals (1997), 40 Detailed reference viewed: 4 (0 ULg)![]() High yield radiosynthesis of p-[F-18]MPPF, 5-HT1A antagonist, and PET studies in cat brain.; Lemaire, Christian ; Plenevaux, Alain et alin Journal of Nuclear Medicine : Official Publication, Society of Nuclear Medicine (1997), 38 Detailed reference viewed: 13 (0 ULg) Evaluation of p-[18F]MPPF, 5-HT1A antagonist, a potential radiopharmaceutical for PET: tissue distribution, autoradiography and metabolism in rats.Plenevaux, Alain ; Aerts, Joël ; Lemaire, Christian et alin Society for Neuroscience / Abstracts (1997), 23 Detailed reference viewed: 5 (1 ULg)![]() Evaluation of p-[F-18]MPPF, 5-HT1A antagonist, in rats: tissue distribution, autoradiography and metabolism.Plenevaux, Alain ; Aerts, Joël ; Lemaire, Christian et alin Journal of Nuclear Medicine : Official Publication, Society of Nuclear Medicine (1997), 38 Detailed reference viewed: 8 (1 ULg) No-carrier-added asymmetric synthesis of alpha-methyl-alpha-amino acids labelled with fluorine-18; Lemaire, Christian ; Plenevaux, Alain et alin Tetrahedron (1997), 53(16), 5785-5796 Various [18F]fluoro aromatic α-methyl-L-amino acids 11 have been synthesized with high enantiomeric purity (ee > 97%). These new radiopharmaceuticals for Positron Emission Tomography (PET), potential ... [more ▼] Various [18F]fluoro aromatic α-methyl-L-amino acids 11 have been synthesized with high enantiomeric purity (ee > 97%). These new radiopharmaceuticals for Positron Emission Tomography (PET), potential inhibitors of enzymatic functions, were regiospecifically labelled by nucleophilic substitution on trimethylammoniumbenzaldehyde triflate precursors 9. The [18F]fluoro aromatic aldehydes 12 obtained were easily converted to the corresponding [18F]fluorobenzyl halides [13 (X = 1)]. After alkylation of the lithium enolate of (2S,5S)-l-tert-Boc-2-tert-butyl-3,5-dimethyl-imidazolidin-4-one 2, the adducts were cleaved to give, after HPLC purification, various [18F]fluoro-α-methyl amino acid analogs with radiochemical yields of 10% (End of Bombardment, EOB) after a synthesis time of 120 min. The corresponding [19F]fluorinated amino acids 4 and [19F]fluoro intermediates were also prepared. [less ▲] Detailed reference viewed: 16 (2 ULg) Combined study of cerebral glucose metabolism and [11C] methionine accumulation in probable Alzheimer's disease using positron emission tomographySalmon, Eric ; ; et alin Journal of Cerebral Blood Flow & Metabolism (1996), 16(3), 399-408 There is a characteristic decrease in glucose metabolism in associative frontal and temporo-parietal cortices of patients suffering from Alzheimer's disease (AD). The decrease in metabolism might result ... [more ▼] There is a characteristic decrease in glucose metabolism in associative frontal and temporo-parietal cortices of patients suffering from Alzheimer's disease (AD). The decrease in metabolism might result from local neuronal loss or from a decrease of synaptic activity. We measured in vivo [11C]methionine accumulation into proteins with positron emission tomography (PET) to assess cortical tissue loss in AD. Both global regional activity and compartmental analysis were used to express [11C]methionine accumulation into brain tissue. Glucose metabolism was measures with [18F]fluorodeoxyglucose and autoradiographic method. Combined studies were performed in 10 patients with probable AD, compared to age-matched healthy volunteers. There was a significant 45% decrease of temporo-parietal glucose metabolism in patients with AD, and frontal metabolism was lowered in most patients. Temporo-parietal metabolism correlated to dementia severity. [11C]methionine incorporation into temporo-parietal and frontal cortices was not significantly decreased in AD. There was no correlation with clinical symptoms. Data suggest that regional tissue loss, assessed by the decrease of [11C]methionine accumulation, is not sufficient to explain cortical glucose hypometabolism, which reflects, rather, reduced synaptic connectivity. [less ▲] Detailed reference viewed: 7 (0 ULg) Enantioselective syntheses of no-carrier-added (nca) (S)-4-chloro-2 F-18 fluorophenylalanine and (S)-(alpha-methyl)-4-chloro-2 F-18 fluorophenylalanine; Plenevaux, Alain ; Lemaire, Christian et alin Journal of Fluorine Chemistry (1996), 80(2), 117-124 (S)-4-Chloro-2-fluorophenylalanine and (S)-( a-methyl)-4-chloro-2-fluorophenylalanine were synthesized and labeled with no carrier added (n.c.a.) fluorine-18 through a radiochemical synthesis relying on ... [more ▼] (S)-4-Chloro-2-fluorophenylalanine and (S)-( a-methyl)-4-chloro-2-fluorophenylalanine were synthesized and labeled with no carrier added (n.c.a.) fluorine-18 through a radiochemical synthesis relying on the highly enantioselective reaction between 4-chloro-2-[18F] fluorobenzyl iodide and the lithium enolate of (2s) -1-( tert-butyloxycarbonyl) -2-( tert-butyl)-3-methyl- 1,3-imidazolidine-4-one for (S) -4-chloro-2- [18F] fluorophenylalanine and (2S,5S)-1-( tert-butyloxycarbonyl) -2-( tert-butyl) -3,5-dimethyl- 1,3-imidazolidine-4-one for (S) -( a-methyl) -4-chloro-2- [18F] fluorophenylalanine. Quantities of about 20-25 mCi were obtained at the end of synthesis, ready for injection after hydrolysis and high performance liquid chromatography (HPLC) purification, with a radiochemical yield of 17%-20% corrected to the end of bombardment after a total synthesis time of 90-105 min from [18F] fluoride. The enantiomeric excesses were shown to be 97% or more for both molecules without chiral separation and the radiochemical and chemical purities were 98% or better. [less ▲] Detailed reference viewed: 46 (6 ULg) Fluorine-18 labeling of radiopharmaceuticals for PET studies: main aspects and problems encountered in chemical synthesesLemaire, Christian ![]() in Emran, A (Ed.) Chemists' Views of Imaging Centers (1995) Detailed reference viewed: 1 (0 ULg)![]() S-, N- and O-[11C]methylations of a Nor precursor adsorbed on Al2O3/KF.; Plenevaux, Alain ; et alin Journal of Labelled Compounds & Radiopharmaceuticals (1995), 37 Detailed reference viewed: 4 (0 ULg)![]() [1-11C]Bromoethane: an alternative to the use of [1-11C]iodoethane.; ; Plenevaux, Alain et alin Journal of Labelled Compounds & Radiopharmaceuticals (1995), 37 Detailed reference viewed: 63 (4 ULg)![]() Fast quality control of short-lived radiopharmaceutical compounds with a photodiode array detector.Plenevaux, Alain ; Lemaire, Christian ; Aerts, Joël et alin Journal of Labelled Compounds & Radiopharmaceuticals (1995), 37 Detailed reference viewed: 6 (1 ULg)![]() Fast routine production of L-[11C-methyl]methionine with Al2O3/KF in a disposable unit.; ; Plenevaux, Alain et alin Journal of Labelled Compounds & Radiopharmaceuticals (1995), 37 ![]() Sep Pak as alternative to rotary evaporators for radiopharmaceutical formulations.Lemaire, Christian ; Plenevaux, Alain ; et alin Journal of Labelled Compounds & Radiopharmaceuticals (1995), 37 Detailed reference viewed: 23 (3 ULg)![]() Glucose hypometabolism in Alzheimer's disease is not related to loss of cortical interneurons bearing 5HT2 receptors.Salmon, Eric ; Lemaire, Christian ; Degueldre, Christian et alin Acta Neurologica Belgica (1995), 95 Detailed reference viewed: 14 (3 ULg) Fast Routine Production of L-[11C-methyl]methionine with Al2O3KF; Plenevaux, Alain ; et alin 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 ▲] Detailed reference viewed: 68 (1 ULg) Serotonin 5HT2 receptor imaging in the human brain using positron emission tomography and a new radioligand, [18F]altanserin: results in young normal controls.Sadzot, Bernard ; Lemaire, Christian ; Maquet, Pierre et alin 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 ▲] Detailed reference viewed: 37 (5 ULg) |
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