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  • 1
    Digitale Medien
    Digitale Medien
    The normal pituitary examined with positron emission tomography and (methyl-11C)-L-methionine and (methyl-11C)-D-methionine (1987)
    Springer
    Neuroradiology 29 (1987), S. 221-225 
    Details
    ISSN: 1432-1920
    Schlagwort(e): Positron emission tomography ; Brain metabolism ; Amino acids ; Stereospecificity ; Pituitary gland
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Four patients with radiologically normal pituitary gland were examined with positron emission tomography after the administration of (methyl-11C)-L-methionine. On a following day the examination was repeated with (methyl-11c)-D-methionine. The accumulation rate of L-methionine in the pituitary was measured, giving a value that was about twice that of normal brain tissue. The accumulation rate of D-methionine in the pituitary was almost a factor of 10 lower than that of L-methionine. In the normal brain tissue that ratio was 2.3. The study clearly indicates that the methionine uptake in the pituitary is stereospecific. 11C-D-methionine is freely distributed in the tissue without entrapment, whereas 11C-L-methionine is irreversibly bound. It is concluded that PET with 11C-L-methionine can be used to study amino acid utilization in the pituitary.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00451757
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  • 2
    Digitale Medien
    Digitale Medien
    Decreased uptake and binding of11C-nicotine in brain of Alzheimer patients as visualized by positron emission tomography (1990)
    Springer
    Journal of neural transmission 2 (1990), S. 215-224 
    Details
    ISSN: 1435-1463
    Schlagwort(e): Positron emission tomography ; PET ; Alzheimer's disease ; (+) (R) N-11C-methyl nicotine ; (−) (S) N-11C-methyl nicotine ; brain ; nicotinic receptors ; cholinergic receptors ; diagnostic marker
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02257652
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  • 3
    Digitale Medien
    Digitale Medien
    Striatal [11C]-N-methyl-spiperone binding in patients with focal dystonia (torticollis) using positron emission tomography (1993)
    Springer
    Journal of neural transmission 5 (1993), S. 79-87 
    Details
    ISSN: 1435-1463
    Schlagwort(e): Positron emission tomography ; PET ; focal dystonia ; torticollis ; [11C]-N-methyl-spiperone ; dopamine receptors
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Specific binding of [11C]-N-methyl-spiperone to striatal dopamine D2 receptors was assessed using positron emission tomography (PET) in 6 patients with adult-onset focal dystonia (predominantly spasmodic torticollis) and in 5 healthy subjects. No significant difference in average specific striatal tracer uptake between patients and healthy subjects was found. However, in the 5 patients showing lateralisation of clinical signs a trend to higher striatal tracer uptake in the contralateral hemisphere was observed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02251198
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  • 4
    Digitale Medien
    Digitale Medien
    Regional brain kinetics of 6-fluoro-(β-11C)-L-dopa and (β-11C)-L-dopa following COMT inhibition. A study in vivo using positron emission tomography (1992)
    Springer
    Journal of neural transmission 87 (1992), S. 15-22 
    Details
    ISSN: 1435-1463
    Schlagwort(e): (β-11C)-L-dopa ; 6-fluoro-(β-11C)-L-dopa ; positron emission tomography ; catechol-O-methyl transferase ; monkeys
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The regional brain kinetics of (β-11C)-L-dopa and 6-fluoro-(β-11C)-L-dopa was measured in six Rhesus monkeys using positron emission tomography (PET). Radioactivity accumulated specifically in the striatal region and the increase in L-dopa-derived radioactivity utilization with time was calculated using surrounding brain as a reference area, this being devoid of dopaminergic activity. The rate constant for selective striatal utilization i.e. grossly decarboxylation was 0.0110 ± 0.0007 (S.D) and 0.0057 ± 0.0006 min1 for (β-11C)-L-dopa and 6-fluoro-(β-11C)-L-dopa, respectively. After pre-treatment of the monkeys with the peripherally and centrally active catecholamine-O-methyl transferase (COMT) inhibitor Ro 40-7592 10 mg/kg, the decarboxylation rate remained unchanged (0.0112 ± 0.0015 min-1) for (β11C)-L-dopa, whereas an increase in rate was measured for 6-fluoro-(β-11C)L-dopa (0.0092 ± 0.0015 min−1). Differences in the distribution of radiolabelled metabolites i.e. the corresponding O-methyl-L-dopa in the reference area is most probably the reason for the difference in calculated decarboxylation rate seen between the radiotracers. The higher decarboxylation rate measured for 6-fluoro-(β-11C)-L-dopa after blockade of COMT shows that the radiolabelled metabolites i.e. 6-fluoro-O-methyl-(β-11C)-L-dopa significantly contributes to background radioactivity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01253107
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  • 5
    Digitale Medien
    Digitale Medien
    Positron emission tomographic studies on aromatic L-amino acid decarboxylase activity in vivo for L-dopa and 5-hydroxy-L-tryptophan in the monkey brain (1993)
    Springer
    Journal of neural transmission 94 (1993), S. 127-135 
    Details
    ISSN: 1435-1463
    Schlagwort(e): 5-Hydroxy-L-(β-11 C)tryptophan ; L-(β-11 C)DOPA ; positron emission tomography ; aromatic amino acid decarboxylase ; monkeys
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The regional brain kinetics following 5-hydroxy-L-(β-11 C)tryptophan and L-(β-11 C)DOPA intravenous injection was measured in twelve Rhesus monkeys using positron emission tomography (PET). The radiolabelled compounds were also injected together with various doses of unlabelled 5-hydroxy-L-tryptophan or L-DOPA. The radioactivity accumulated in the striatal region and the rate of increased utilization with time was calculated using a graphical method with back of the brain as a reference region. The rate constants for decarboxylation were 0.0070 ± 0.0007 (S. D) and 0.0121±0.0010min−1 for 5-hydroxy-L-(β-11C)tryptophan and L-(β-11 C)DOPA, respectively. After concomitant injection with unlabelled 5-hydroxy-L-tryptophan, the rate constant of 5-hydroxy-L-(β-11 C)tryptophan decreased dose-dependently and a 50 percent reduction was seen with a dose of about 4mg/kg of unlabelled compound. A decreased utilization rate of L-(β-11 C)DOPA was seen only after simultaneous injection of 30 mg/kg of either L-DOPA or 5-hydroxy-L-tryptophan. This capacity limitation was most likely interpreted as different affinity of the striatal aromatic amino acid decarboxylase for L-DOPA and 5-hydroxy-L-tryptophan, respectively.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01245006
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  • 6
    Digitale Medien
    Digitale Medien
    PET radiopharmaceuticals in Europe: Current use and data relevant for the formulation of summaries of product characteristics (SPCs) (1995)
    Springer
    European journal of nuclear medicine 22 (1995), S. 1420-1432 
    Details
    ISSN: 1619-7089
    Schlagwort(e): Positron emission tomography ; PET ; Radiopharmaceuticals ; Quality criteria ; Toxicology ; Dosimetry ; Survey
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The increasing use of radiopharmaceuticals for positron emission tomography (PET) has come to the attention of regulatory bodies. In order to help authorities in all aspects, the EANM has formed a task group for licensing PET radiopharmaceuticals; this group has surveyed the use of these compounds in Europe by a questionnaire. The number of PET centres that responded to the questionnaire was 26, which included more than 90% of the larger European PET centres. The survey showed that 2-[18F]fluoro-2-deoxyglucose is by far the most important PET radiopharmaceutical with more than 200 applications per week, followed by [15O]water, [15O]carbonmonoxide, [13N]ammonia, [11C]-l-methionine, andl-6-[18F]fluoro-DOPA. More than 25 other PET radiopharmaceuticals are in regular use, however, at rather low application frequencies. The data were used by the European Pharmacopoeia Commission for its priority rating for requesting the formulation of monographs. Since it is likely that group registrations will be issued by authorities for the PET radiopharmaceuticals, relevant data on toxicity and dosimetry for the formulation of summaries of product characteristics have been collected by the task group as well.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01791152
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  • 7
    Digitale Medien
    Digitale Medien
    Amphetamine effects on dopamine release and synthesis rate studied in the Rhesus monkey brain by positron emission tomography (1997)
    Springer
    Journal of neural transmission 104 (1997), S. 329-339 
    Details
    ISSN: 1435-1463
    Schlagwort(e): Amphetamine ; [11C] ; L-DOPA ; raclopride ; N-methylspiperone ; CBF ; PET ; monkeys
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Positron emission tomography (PET) was used in a multitracer protocol to evaluate D-amphetamine induced effects on dopamine biosynthesis rate and release in propofol anesthetized Rhesus monkeys.l-[β-11C]DOPA was used as biochemical probe to study the brain dopamine biosynthesis rate whilst dopamine release was followed by the binding displacement of the [11C]-radiolabelled dopamine receptor antagonists, raclopride and N-methylspiperone. Studies were performed with either a constant rate intravenous infusion of D-amphetamine aiming at plasma concentrations of 0.2 to 25 ng/ml or with intravenous bolus doses of 0.1 and 0.4 mg/ kg. Decreased binding of the dopamine receptor antagonists was measured in both modes of D-amphetamine administration but notably [11C]N-methylspiperone was less able to sense D-amphetamine induced release of dopamine. At plasma concentrations aimed above 1 ng/ml a levelling off of the binding of [11C]raclopride at 68 ± 8.1% of the baseline value indicated that displacement was only possible from a fraction of the binding sites. Amphetamine was observed to increase the rate constant forl-[β-11C]DOPA utilization in the brain. This was most likely due to an acutely induced subsensitivity of presynaptic dopamine receptors.l-[β-11C]DOPA and [11C]raclopride were found suitable to indicate changes in dopamine synthesis rate and release respectively using PET and can be used to mirror drug-induced changes of brain dopaminergic function.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01277655
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