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GABAB (gamma-aminobutyric acid)-receptors have been implicated in central nervous system (CNS) functions, e.g. cognition and pain perception, and dysfunctions including spasticity and absence epilepsy. To permit an analysis of the two known GABAB-receptor splice variants GABAB-R1a (GB1a) and GABAB-R1b (GB1b), their distribution pattern has been(More)
The subunit architecture of gamma-aminobutyric acid, type B (GABA(B)), receptors in situ is largely unknown. The GABA(B) receptor variants, characterized by the constituents GBR1a and GBR1b, were therefore analyzed with regard to their subunit composition as well as their regional and subcellular distribution in situ. The analysis was based on the use of(More)
UNLABELLED (11)C-ABP688 (3-(6-methyl-pyridin-2-ylethynyl)-cyclohex-2-enone-O-(11)C-methyl-oxime), a noncompetitive and highly selective antagonist for the metabotropic glutamate receptor subtype 5 (mGluR5), was evaluated for its potential as a PET agent. METHODS ABP688 was radiolabeled with (11)C by reacting (11)C-methyl iodide with the sodium salt of(More)
Native GABAA receptors containing different gamma-subunit variants were distinguished immunobiochemically with antisera selectively recognizing the gamma 1-, gamma 2- and gamma 3-subunits. While GABAA receptors containing the gamma 2-subunits were confirmed to be rather ubiquitous in the adult brain, receptors characterized by the gamma 1- or gamma(More)
The binding site for the co-agonist glycine on N-methyl-D-aspartate (NMDA) receptors has been mapped to the NR1 subunit whereas binding of the principal agonist glutamate is mediated by the NR2 subunits. Using the novel glycine site antagonist and photoaffinity label CGP 61594, distinct contributions of the NR2 subunit variants to the glycine antagonist(More)
UNLABELLED The novel, dedicated small animal PET tomograph, quad-HIDAC, offers submillimeter resolution in instrumental characterization experiments. The aim of this study was to establish the tomograph's utility in a biologic application and to demonstrate the feasibility of rapid dynamic neuroreceptor imaging in mice. METHODS We used the(More)
PURPOSE The combined treatment modality of ionizing radiation with inhibitors of angiogenesis is effective despite the supposition that inhibition of angiogenesis might increase tumor hypoxia and thereby negatively affect radiation sensitivity. To directly assess this still controversial issue, we analyzed treatment-dependent alterations of tumor(More)
Bombesin receptors are under intense investigation as molecular targets since they are overexpressed in several prevalent solid tumors. We rationally designed and synthesized a series of modified bombesin (BN) peptide analogs to study the influence of charge and spacers at the N-terminus, as well as amino acid substitutions, on both receptor binding(More)
BACKGROUND Noninvasive preclinical imaging methodologies such as small animal positron emission tomography (PET) allow the repeated measurement of the same subject which is generally assumed to reduce the variability of the experimental outcome parameter and to produce more robust results. In this study, the variability of tracer uptake in the rodent brain(More)
INTRODUCTION The clinically established positron emission tomography (PET) tracers 6-[(18)F]-fluoro-l-DOPA ([(18)F]FDOPA), 6-[(18)F]-fluoro-l-m-tyrosine ([(18)F]FMT) and 2beta-carbomethoxy-3beta-(4-chlorophenyl)-8-(2-[(18)F]-fluoroethyl)-nortropane ([(18)F]FECNT) serve as markers of presynaptic integrity of dopaminergic nerve terminals in humans. This study(More)