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  • Electronic Resource  (4)
  • nicotinic receptors  (3)
  • 5-Hydroxy-(β-11 C)-L-tryptophan  (1)
  • 1
    ISSN: 1435-1463
    Keywords: Positron emission tomography ; PET ; Alzheimer's disease ; (+) (R) N-11C-methyl nicotine ; (−) (S) N-11C-methyl nicotine ; brain ; nicotinic receptors ; cholinergic receptors ; diagnostic marker
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Positron emission tomography of the brain following intravenous injection of (+) (R) and (−) (S) N-[11C-methyl]nicotine showed a marked reduced uptake of both isomers, especially the (R) form, in Alzheimer patients as compared to age-matched controls. The significantly larger difference between the uptake values of the (S)- and (R)-enantiomers of11C-nicotine in Azheimer brains may be of diagnostic value.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1435-1463
    Keywords: Alzheimer's disease ; nerve growth factor ; positron emission tomography ; nicotine binding ; cerebral blood flow ; episodic memory ; EEG ; nicotinic receptors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Based on animal research suggesting that nerve growth factor (NGF) can stimulate central cholinergic neurons, the known losses of cholinergic innervation of the cortices in Alzheimer's disease (AD), and our experience of infusing NGF to support adrenal grafts in parkinsonian patients, we have initiated clinical trials of NGF infusions into the brain of patients with AD. Here we report a follow-up of our first case, a 69-year-old woman, with symptoms of dementia since 8 years. Intraventricular infusion of 6.6 mg NGF during three months resulted in a marked transient increase in uptake and binding of11C-nicotine in frontal and temporal cortex and a persistent increase in cortical blood flow as measured by PET as well as progressive decreases of slow wave EEG activity. After one month of NGF, tests of verbal episodic memory were improved whereas other cognitive tests were not. No adverse effects could be ascribed to the NGF infusion. Taken together, the results of this case study indicate that NGF may counteract cholinergic deficits in AD, and suggest that further clinical trials of NGF infusion in AD are warranted.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1435-1463
    Keywords: 5-Hydroxy-(β-11 C)-L-tryptophan ; monkey ; positron emission tomography ; enzyme inhibition ; decarboxylation rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 5-Hydroxy-L-tryptophan labelled with 11 C is introduced as a tracer for the in vivo assessment of brain serotonin synthesis in the Rhesus monkey using positron emission tomography, PET. Increasing radioactivities were seen in the striatal area in contrast to that seen in other brain regions. Following 11 C-labelled L-tryptophan an even spread of brain radioactivity was seen. This selective increase most probably results from the decarboxylation of tracer and retention of formed products since no striatal increase of radioactivity was seen when 5-hydroxy-L-tryptophan labelled with 11 C in the carboxy-position was administered. Furthermore, pretreatment of the monkey with a centrally active decarboxylase inhibitor (NSD 1015,10 mg/kg) did not lead to increased striatal radioactivities after the administration of 5-hydroxy-(β-11C)-L-tryptophan. The selective utilization of the radiotracer in the striatal area increased with a rate constant calculated to be 0.0055 ± 0.0015 min−1 (n = 5) using the surrounding brain as reference area. A non-significant influence of radiolabelled metabolites to the rate constants measured was shown after pretreatment of the monkeys with selective and non-selective monoamine oxidase inhibitors, respectively. These results may give a basis for the use of the new tracer 5-hydroxy-(β-11 C)-L-tryptophan in PET-studies of brain serotonin metabolism in health and disease.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1435-1463
    Keywords: Monkey ; positron emission tomography ; 11C-nicotine ; optic enantiomers ; nicotinic receptors ; brain ; regional distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary N-[methyl-11C] nicotine (11C-nicotine) was given intravenously to monkeys and the uptake and regional distribution of radioactivity was followed in the brain using positron emission tomography (PET). The11C-radioactivity in the brain peaked within 1–2 min and then rapidly declined. Pretreatment with unlabelled nicotine (10 μg/kg) reduced the uptake of11C-radioactivity to the brain by 30%. The uptake of radioactivity was higher following (+)11C-nicotine than (−)11C-nicotine. Both enantiomers were distributed in a similar manner within the brain. When animals were infused with a peripheral nicotinic blocker (trimetaphan) the uptake of radioactivity to the brain was lower following (+)11C-nicotine compared to (−)11C-nicotine. The amount of radioactivity was high in the occipital cortex, thalamus, intermediate in the frontal cortex and low in white matter in (−)11C injected monkeys while no regional difference in distribution of11C-radioactivity was observed after injection of (+)11C-nicotine.
    Type of Medium: Electronic Resource
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