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  • 1
    ISSN: 1619-7089
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In order to study “in vivo” the distribution kinetics of (-)-nicotine in animals, this molecule was labeled with carbon-11. Two synthesis methods are described. Immediately after intravenous administration of (-)-nicotine-methyl-11C in rabbits the gamma-camera shows a strong radioactivity build-up in the brain and kidneys. The biological interest of this carbon-11 labeled molecule is discussed.
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  • 2
    ISSN: 1619-7089
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Carbon 11 which is a 20.4 minutes half life isotope emitting positrons was used for methionine labelling on the methyl group by action of 11C-methyl-iodide on DL or L homocysteine. With the method described, 20 to 30 mCi of 11C-methyl-methionine (Specific activity 50 mCi/μM) may be obtained within 25 minutes. The 20 Mev proton beam used for 11C production was 10 μA. The metabolism of 11C methionine studied on mice shows a high uptake in pancreas and to a smaller extent in brain. On humans sequential images were obtained at the head level which allowed measurement of the uptake of the radio-labelled compound in the brain so as to study the radioactivity curve in different parts of the organ.
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  • 3
    ISSN: 1573-2800
    Keywords: POSITRON EMISSION TOMOGRAPHY ; VISUALSTIMULATION ; SEXUAL AROUSAL ; INFERIOR TEMPORAL CORTEX ; INSULA ; INFERIOR FRONTAL CORTEX ; CINGULATECORTEX ; PARALIMBIC CORTEX ; TESTOSTERONE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Psychology
    Notes: Abstract Brain areas activated in human male sexualbehavior have not been characterized precisely. For thefirst time, positron emission tomography (PET) was usedto identify the brain areas activated in healthy males experiencing visually evoked sexualarousal. Eight male subjects underwent six measurementsof regional brain activity following the administrationof [15O]H2O as they viewedthree categories of film clips: sexually explicit clips,emotionally neutral control clips, and humorous controlclips inducing positive but nonsexual emotions.Statistical Parametric Mapping was used to identifybrain regions demonstrating an increased activity associatedwith the sexual response to the visual stimulus.Visually evoked sexual arousal was characterized by athreefold pattern of activation: the bilateralactivation of the inferior temporal cortex, a visualassociation area; the activation of the right insula andright inferior frontal cortex, which are two paralimbicareas relating highly processed sensory information with motivational states; and the activation ofthe left anterior cingulate cortex, another paralimbicarea known to control autonomic and neuroendocrinefunctions. Activation of some of these areas was positively correlated with plasma testosteronelevels. Although this study should be consideredpreliminary, it identified brain regions whoseactivation was correlated with visually evoked sexualarousal in males.
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  • 4
    ISSN: 1619-7089
    Keywords: Melanoma ; radionuclide imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Seventy Syrian golden hamsters bearing SC transplants of Greene melanoma were used to evaluate the degree of tumour uptake of several 11C-radiopharmaceuticals selected for their potential specificity for melanoma. Tissue distribution studies were performed at 30 and 60 min after IV injection of 11C-compounds and compared with the 24-h uptake of 67Ga-citrate. Gamma camera images were also compared. The highest tumour uptake at 1 h was observed with 11C-methionine (2.42%±0.72%) and although activity in liver, spleen and kidney exceeded that in melanoma the tumour was demonstrated on gamma camera imaging. Melanoma localisation of 11C-chlorpromazine, 11C-flunitrazepam and 11C-ketanserine was comparable at 1% of the dose injected per gram of tumour. High activity in other organs, particularly liver, exceeded uptake in melanoma and attempts at tumour imaging were unsuccessful. Tumour accumulation of 11C-methiodide quinuclidinyl benzylate (MQNB), an 11C-imidazobenzodiazepine (Ro-15-1788) and 14C-pimozide was low and imaging studies were not attempted. None of the 11C-radiopharmaceuticals evaluated for melanoma affinity matched that of 67Ga-citrate. The 24-h tumour uptake of 67Ga-citrate was 4.07%±1.37% dose injected per gram which allowed delineation of the melanoma by gamma camera imaging.
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  • 5
    ISSN: 1619-7089
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A methylated derivative of serotonin, O-methyl-bufotenine has been labeled with 11C on the two methyl groups of the amine function. In order to avoid the cyclization which occurs during the Eschweiler-Clarke synthesis, we adopted a milder methylation procedure, based on Borch's method using [11C]formaldehyde and sodium cyanoborohydride. Several tens of millicuries of injectable product could be obtained in 50 min in a perfectly pure state and having a specific radioactivity of 50 to 100mCi/μmol. The distribution study of O-methyl-bufotenine in the mouse and rabbit showed an accumulation of significant quantities of the compound in the brain, kidneys, lungs and liver. The study of the rapid kinetics of this hallucinogenic molecule is compatible with labeling by 11C, having a period of 20 min. The use of O-methyl-[11C]bufotenine to detect serotonin receptors in vivo in mental diseases, is considered.
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