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  • 1
    Electronic Resource
    Electronic Resource
    Initial human studies with single-photon emission tomography using iodine-123 labelled 3-(5-cyclopropyl-1,2,4-oxadiazo-3-yl)-7-iodo-5,6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5-a][1,4]-benzodiazepine (NNC 13-8241) (1996)
    Springer
    European journal of nuclear medicine 23 (1996), S. 798-803 
    Details
    ISSN: 1619-7089
    Keywords: Benzodiazepine ; Dynamic single-photon emission tomography ; Iodine-123-3-(5-cyclopropyl1,2,4-oxadiazo-3-yl)-7-iodo-5,6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5-a][1,4]-benzodiazepine ; Receptors ; NNC 13-8241
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The iodine-123 labelled ligand 3-(5-cyclopropyl-1,2,4-oxadiazo-3-yl)-7-iodo-5,6-dihydro-5-methyl-6oxo-4H-imidazo[1,5-a][1,4]-benzodiazepine ([123I]NNC 13-8241) was evaluated as a probe for in vivo imaging of benzodiazepine receptor sites in the human brain. Four healthy volunteers were imaged with a high-resolution single-photon emission tomography (SPET) scanner. The metabolism of [123I]NNC 13-8241 in plasma was slow. The total brain uptake was about 1.5-fold higher than that of [123I]iomazenil. The specific binding in the cortical areas was high and less intense in the thalamus. The most intense uptake was seen in the occipital cortex. The peak cortical uptake of [123I]NNC 13-8241 was observed 6–10 h after the injection of tracer. The radiation burden to the patient was moderate, being 2.5·10−2 mSv/MBq (effective dose equivalent). A slow metabolism together with favourable kinetics indicates that [123I]NNC 13-8241 is a specific and promising SPET ligand for imaging benzodiazepine receptor sites in the living human brain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00843709
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  • 2
    Electronic Resource
    Electronic Resource
    Preparation of a potential positron emission tomographic radioligand for the dopamine transporter (1994)
    Springer
    European journal of nuclear medicine 21 (1994), S. 131-137 
    Details
    ISSN: 1619-7089
    Keywords: Dopamine transporter ; NNC 12-0722 ; Carbon-11 ; Positron emission tomography ; In vitro autoradiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract NNC 12-0722 (1-[2-(bis(4-fluorophenyl)methoxy)ethyl]-4-methyl piperazine) is a new selective inhibitor of the dopamine transporter. [11C]NNC 12-0722 was prepared by N-methylation of the desmethyl compound with [11C]methyl iodide. The total radiochemical yield of [11C]NNC 12-0722 was 40%–50% with an overall synthesis time of 30–35 min. The radiochemical purity was higher than 99% and the specific radioactivity about 1500 Ci/mmol (55 GBq/μmol). Autoradiographic examination of [11C]NNC 12-0722 binding on whole hemisphere cryosections from human brain post mortem demonstrated specific binding in the caudate nucleus and putamen. In a positron emission tomographic examination of [11C]NNC 12-0722 in a cynomolgus monkey there was a rapid uptake of radioactivity in the brain. In the striatum, a region with a high density of dopamine transporters, the radioactivity was two times higher than in the cerebellum. These results indicate that [11C]NNC 12-0722 may be a useful radioligand for labelling of the dopamine transporter in man.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00175760
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  • 3
    Electronic Resource
    Electronic Resource
    Bromine-76 and carbon-11 labelled NNC 13-8199, metabolically stable benzodiazepine receptor agonists as radioligands for positron emission tomography (PET) (1997)
    Springer
    European journal of nuclear medicine 24 (1997), S. 1261-1267 
    Details
    ISSN: 1619-7089
    Keywords: Key words: NNC 13-8199 ; Benzodiazepine receptor agonist ; Positron emission tomography ; Carbon-11 ; Bromine-76
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. NNC 13-8241 has recently been labelled with iodine-123 and developed as a metabolically stable benzodiazepine receptor ligand for single-photon emission computed tomography (SPECT) in monkeys and man. NNC 13-8199 is a bromo-analogue of NNC 13-8241. This partial agonist binds selectively and with subnanomolar affinity to the benzodiazepine receptors. We prepared 76Br labelled NNC 13-8199 from the trimethyltin precursor by the chloramine-T method. Carbon-11 labelled NNC 13-8199 was synthesised by N-alkylation of the nitrogen of the amide group with [11C]methyl iodide. Positron emission tomography (PET) examination with the two radioligands in monkeys demonstrated a high uptake of radioactivity in the occipital, temporal and frontal cortex. In the study with [76Br]NNC 13-8199, the monkey brain uptake continued to increase until the time of displacement with flumazenil at 215 min after injection. For both radioligands the radioactivity in the cortical brain regions was markedly reduced after displacement with flumazenil. More than 98% of the radioactivity in monkey plasma represented unchanged radioligand 40 min after injection. The low degree of metabolism indicates that NNC 13-8199 is metabolically much more stable than hitherto developed PET radioligands for imaging of benzodiazepine receptors in the primate brain. [76Br]NNC 13-8199 has potential as a radioligand in human PET studies using models where a slow metabolism is an advantage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002590050150
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  • 4
    Electronic Resource
    Electronic Resource
    PET examination of [11C]NNC 687 and [11C]NNC 756 as new radioligands for the D1-dopamine receptor (1993)
    Springer
    Psychopharmacology 113 (1993), S. 149-156 
    Details
    ISSN: 1432-2072
    Keywords: Positron emission tomography ; D1-dopamine receptors ; NNC 687 ; NNC 756 ; Cynomolgus monkey ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The benzazepines NNC 687 and NNC 756 have in animal studies been described as selective D1-dopamine receptor antagonists. Both compounds have been labeled with11C for examination by positron emission tomography (PET). In the present study central receptor binding was studied in monkeys and healthy men. After IV injection of both radioligands in Cynomolgus monkeys radioactivity accumulated markedly in the striatum, a region with a high density of D1-dopamine receptors. This striatal uptake was displaced by high doses of the selective D1-antagonist SCH 23390 (2 mg/kg) but not by the 5HT2-antagonist ketanserin (1.5 mg/kg) or the selective D2-antagonist raclopride (3 mg/kg). The cortical uptake after injection of [11C]NNC 687 was not reduced in displacement experiments with ketanserin. The cortical uptake of [11C]NNC 756 was reduced in displacement and protection experiments with ketanserin by 24–28% (1.5 mg/kg), whereas no reduction could be demonstrated on striatal uptake. In healthy males both compounds accumulated markedly in the striatum. For [11C]NNC 687 the ratio of radioactivity in the putamen to cerebellum was about 1.5. For [11C]NNC 756 the ratio was about 5. This ratio of 5 for [11C]NNC 756 is the highest obtained so far for PET radioligands for the D1-dopamine receptor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245691
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