Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1432-1920
    Keywords: Positron emission tomography ; Brain metabolism ; Amino acids ; Stereospecificity ; Pituitary gland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Neuroradiology 29 (1987), S. 585-587 
    ISSN: 1432-1920
    Keywords: Stereotaxic techniques ; Digital radiography ; Leksell instrument
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Special perspex adaptors with radiopaque reference structures have been constructed to fit to the Leksell stereotaxic instrument. These structures are visualized on X-ray film in a radiographic examination like angiography or encephalography. The films obtained in two projections at arbitrary angles and focus-film-distances are placed on a digitizing table for the determination of the stereotaxic coordinates of selected targets. The reference structures and the targets are marked with a cursor whereupon a desk top computer performs the calculation of the stereotaxic coordinates. The system allows a rapid, simple and accurate coordinate determination in stereotaxic radiography using the Leksell stereotaxic instrument.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Neuroradiology 28 (1986), S. 100-104 
    ISSN: 1432-1920
    Keywords: Stereotaxic techniques ; Brain imaging ; Angiography ; Radiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A method for the determination of stereotaxic coordinates in radiography, e.g. angiography, pneumoencephalography or digital vascular radiography, is described. A special localization frame containing radiopaque structures and scales defines a diagnostic coordinate system. This frame is fixed to the X-ray-table prior to the radiographic procedure and two projections are obtained at arbitrary angles to each other. The focus-film distances do not how to be fixed. The target coordinates are then determined either by a simple graphical procedure or with the use of a digitizing x-y-table, by a computer. With the computer method the films are placed on the digitizing table and the target and a few reference points are marked using a cursor. From the relative positions the computer calculates the coordinates. With the special head fixation system, coordinates of structures visualized in radiographic examinations can be transferred to various therapeutic or diagnostic stereotaxic devices.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1432-2072
    Keywords: Key words PET ; Pharmacokinetics ; Dopamine D2 receptor ; Serotonin 5HT2 receptor ; Atypical antipsychotic ; Quetiapine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Quetiapine (Seroquel) is a novel antipsychotic with an atypical profile in animal models and a relatively short plasma half-life of 2.5–5 h. In the present study, we used PET to compare the time course of blockade of dopamine D2 and serotonin 5HT2 receptors of quetiapine using C11-raclopride and C11-N-methyl-spiperone as ligands, parallel to monitoring plasma drug concentrations. It was an open study in 11 schizophrenic men using a fixed dose of 450 mg quetiapine. Eight men completed the 29 days treatment, followed by four PET scans performed over a 26-h period after withdrawal of the compound. Quetiapine was shown to bind to dopamine D2 receptors in striatum and 2 h (tmax) after the last dose, 44% receptor occupancy was calculated. After 26 h it had dropped to the same level as was found in untreated healthy volunteers. Serotonin 5HT2 receptor blockade in the frontal cortex was 72% after 2 h, which declined to 50% after 26 h. The terminal plasma half-life of quetiapine was 5.3 h. Clinically, our eight patients had good antipsychotic effect without any extrapyramidal side-effects. Our data shows that quetiapine has a relatively low affinity for dopamine D2 receptors, with an occupancy half-life (10 h), which was about twice as long as that for plasma. A more prolonged blockade of the serotonin 5HT2 receptors was found in the frontal cortex, with receptor occupancy half-life of 27 h. Compared to clozapine, as demonstrated in other studies, quetiapine has much the same ratio of D2/5HT2 occupancy. This could suggest that the combination of D2/5HT2 receptor blockade contributes to the antipsychotic effect and a low incidence of EPS seen with quetiapine in comparative phase three trials. Our results also confirm the clinical data that quetiapine can be administered twice daily.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1432-2161
    Keywords: Key words Skeletal metastases ; PET ; Fluoride ; CT
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Objective. To characterise the uptake of 18F in skeletal metastases from breast cancer using positron emission tomography (PET) and to relate these findings to the appearance on CT. Patients and design. PET with 18F and CT were performed in five patients with multiple skeletal metastases from breast cancer. The CT characteristics were analysed in areas with high uptake on the PET study. Dynamic PET imaging of the skeletal kinetics of the 18F-fluoride ion were included. Results. The areas of abnormal high accumulation of 18F correlated well with the pathological appearance on CT. Lytic as well as sclerotic lesions had markedly higher uptake than normal bone, with a 5–10 times higher transport rate constant for trapping of the tracer in the metastatic lesions than in normal bone. Conclusion. PET with 18F-fluoride demonstrates very high uptake in lytic and sclerotic breast cancer metastases.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    ISSN: 1434-601X
    Keywords: PACS:21.10.Tg Lifetimes – 25.70.Gh Compound nucleus – 27.60.+j 90 ≤ A ≤ 149
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. A new high-spin isomer in 145Sm was observed by in-beam γ-ray spectroscopy with the reaction 122Sn(27Al,3np) at 127 MeV performed at the Nordball multi-detector array in Roskilde. The excitation energy of the isomer was determined to be E x= 11147 keV, and using the generalized centroid-shift method its half-life was found to be T 1/2= (7.4 ± 1.0) ns.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...