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  • 1
    ISSN: 1432-1041
    Keywords: Key words Positron emission tomography ; Esuprone; antidepressive drugs ; MAO-A ; moclobemide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: The aim of the study was to investigate whether or not esuprone binds substantially to MAO-A in the human brain. Methods: In a randomised double-blind placebo-controlled study 16 male healthy volunteers were examined␣with positron emission tomography (PET) with [11C]harmine. Eight of the volunteers were given daily doses of 800 mg esuprone, four were given bi-daily doses of 300 mg moclobemide, and four volunteers were given placebo tablets. PET was performed before initiation of a 7-day treatment period. On day 7, one investigation was made immediately before administration of the drug, representing 23 h after the previous day's treatment for esuprone and 11 h after the last tablets of moclobemide. Further investigations were made 4 h and 8 h after the morning dose on day 7. Results: PET showed a high degree of binding of [11C]harmine, a high-affinity ligand for MAO-A, before the start of treatment, and a marked and similar reduction after treatment with esuprone and moclobemide. A slight tendency for normalisation of enzyme binding was observed at the last time point. In the placebo group no change was observed. Plasma kinetics of esuprone showed a rapid elimination with a half-life of about 4 h. Conclusion: The study demonstrates that esuprone was comparable to moclobemide in its effect on MAO-A inhibition in the brain at the doses given. This is an illustration of the potential of PET to monitor drug effects directly on target biochemical systems in the brain in human volunteers, and the possibility of using these data, rather than pharmacokinetic data, for the determination of dosing intervals.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0942-0940
    Keywords: Computer tomography ; titanium clips ; artefacts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To eliminate the occurrence of artefacts produced by clips on the CT images, the use of titanium clips is suggested. Testsin vitro andin vivo indicate that clips manufactured from 0.2 mm thick 99.9 per cent titanium do not cause artefacts. They are resistant to corrosion, nontoxic, effective, easy to handle, relatively cheap, and are visible on plain X-ray films.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1435-1463
    Keywords: Keywords: NMDA-receptor ; cyano-dizocilpine ; positron emission tomography ; in vitro investigation ; in vivo investigation.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary. (+)-3-[11C]Cyano-5-methyl-10,11-dihydro-5H-dibenzo[a,d]-cyclohepten-5,10-imine ([11C]MKC) was successfully synthesized as a potential radiotracer for PET studies on the NMDA receptor channel complex. In vitro binding properties of [11C]MKC were investigated with newly developed techniques for efficient evaluation of 11C-labeled compounds. The association curve of [11C]MKC binding in rat forebrain membranes showed that the specific binding reached an equilibrium within 30 min. Specific binding was saturable with affinity constant KD = 8.2 ± 0.4 nM and Bmax = 1.62 ± 0.04 pmol/mg protein with glutamate and glycine included in the incubation medium. The binding of [11C]MKC was decreased by extensive washing of the membrane preparation. (+)- and (−)-Dizocilpine, 3-cyano-dizocilpine, and ketamine inhibited the specific binding of [11C]MKC with IC50 values of 37.3, 445.0, 65.8 nM and 3.91 μM, respectively. High specific binding in in vitro autoradiography was distributed predominantly in telencephalic regions (the hippocampus, cerebral cortex, and striatum) followed by thalamus. PET studies using rhesus monkeys under anesthesia showed high uptake of [11C]MKC in the temporoparietal and frontal cerebral cortices, striatum, and thalamic regions, although it is problematic to verify the specific binding in vivo by PET.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1435-1463
    Keywords: Keywords: Brain slice ; positron emitting tracer ; triazolam ; muscarinic acetylcholine receptor ; amnesia.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary. The effect of triazolam, a potent benzodiazepine (BZ) agonist, on muscarinic acetylcholinergic receptor (mAChR) binding was investigated in living brain slices by use of a novel positron-based imaging technique. Fresh rat brain slices were incubated with [11C]N-methyl-4-piperidylbenzilate ([11C]NMPB), a mAChR antagonist, in oxygenated Krebs-Ringer solution at 37°C. During incubation, time-resolved imaging of [11C]NMPB binding in the slices was constructed on the storage phosphor screens. Addition of triazolam (1 μM) plus muscimol (30 μM), a GABAA receptor agonist, to the incubation mixture decreased the specific binding of [11C]NMPB. Ro15-1788, a BZ receptor antagonist, prevented this effect, indicating that the effect was exerted through the GABAA/BZ receptor complex. These results demonstrated that stimulation of the GABAA/BZ receptor lowers the affinity of the mAChR for its ligand, which may underlie the BZ-induced amnesia, a serious clinical side effect of BZ. No such effect in the P2-fraction instead implies that the integrity of the neuronal cells and/or their environment is prerequisite for the modulation of mAChR by GABAA/BZ stimulation.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1434-601X
    Keywords: PACS:21.10.Re Collective levels – 27.60+j 90 ≤ A ≤ 149
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: Excited states of the nucleus ν123Xe have been investigated with the fusion–evaporation-reaction ν110Pd(ν18O,5n)ν123Xe at 86 MeV beam energy, using the compton-suppressed Nordball-multidetector-system at the Niels-Bohr-Institute in Risø, Denmark. The level scheme of ν123Xe was extended up to a level of tentative 53/2+ħ. Four excited bands of 3-quasiparticle-character were observed. Analyzing the directional correlation information, we could assign spin- and parity-values to all observed bands in ν123Xe. The observed band structures fit well into systematics of the neighboring nuclei ν125Xe and ν127Xe.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Neuroradiology 11 (1976), S. 35-40 
    ISSN: 1432-1920
    Keywords: Intravenous angiography ; Computerized axial tomography ; Limitations contrast enhancement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Using a polystyrene phantom and various concentrations of iodine contrast material, the discrimination of blood vessels by the EMI scanner was studied. Although a 2 mm tube can be delineated using high concentrations of iodine, smaller tubes are not seen due to noise inherent in the system.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-1920
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A ring detector positron camera system for CT of the brain is described. The system uses 95 NaI (Tl) detectors, arranged with cylindrical geometry, for the simultaneous detection of coincidences from 1900 detector combinations. With a new sampling technique an experimental system resolution of 7 mm FWHM has been obtained. The sensitivity was found to be 5300 c/s with a 100-keV energy threshold and using a 19.2-cm-diameter cylindrical phantom with a homogeneous specific activity of 1 μCi/cm3. A clinical study of blood-brain barrier damage using 68Ga-EDTA is reported.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Neuroradiology 17 (1978), S. 31-33 
    ISSN: 1432-1920
    Keywords: Computed tomography ; Contrast medium enhancement ; Acoustic neuroma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The changes of the enhancement of the lesion with time after intravenous administration of contrast medium were measured with computed tomography (CT) in 23 cases of acoustic neuroma. The pattern of high initial enhancement followed by a fairly rapid decrease is confirmed. A more rigorous study of the enhancement pattern using a mathematical description of the enhancement curve of the tumor as well as a measurement of the individual blood enhancement curve is discussed.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Neuroradiology 15 (1978), S. 165-166 
    ISSN: 1432-1920
    Keywords: Computed tomography ; Cerebrospinal fluid ; Attenuation value
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The attenuation value of CSF, obtained by lumbar puncture, was determined with computed tomography in 25 patients. Measurement of the protein content in the same samples showed no correlation with the attenuation value. It is concluded that in the normal range of protein concentrations, the effect on the attenuation is insignificant and that the attenuation value of the CSF might be used to check large deviations in the CT numbers due to artifacts.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Neuroradiology 18 (1979), S. 249-258 
    ISSN: 1432-1920
    Keywords: Computed tomography, head ; Pituitary gland, neoplasms ; Sella turcica, anatomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Suspected lesions in and around the sella were examined by CT in 129 cases. The diagnostic accuracy and various technical aspects of the method are described. The mean attenuation and enhancement after administration of contrast material are evaluated in craniopharyngiomas, chromophobe adenomas, meningiomas, aneurysms, dermoid cysts, an arachnoid cyst and a glioma. The choice of collimator and its use in relation to sellar dimensions, particularly the sellar depths, are emphasized.
    Type of Medium: Electronic Resource
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