Vladimir Stepanov

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Only recently the first successful serotonin 2A (5-HT2A) receptor agonist PET radioligands have been described, with [(11)C]Cimbi-36 reported as the most promising in the pig brain so far. Agonist radioligands may target specifically the G protein-coupled state of the receptors and thereby provide a more meaningful assessment of available receptors than(More)
Phosphodiesterase 10A (PDE10A) is considered to be a key target for the treatment of several neuropsychiatric diseases. The characteristics of [(11) C]T-773, a novel positron emission tomography (PET) radioligand with high binding affinity and selectivity for PDE10A, were evaluated in autoradiography and in nonhuman primate (NHP) PET. Brain PET measurements(More)
INTRODUCTION Phosphodiesterase 10A (PDE10A) is a dual-substrate PDE that hydrolyzes both cAMP and cGMP and is selectively expressed in striatal medium spiny neurons. Recent studies have suggested that PDE10A inhibition is a novel approach for the treatment of disorders such as schizophrenia and Huntington's disease. A positron emission tomography (PET)(More)
[11C]T-773 is a new radioligand for positron emission tomography (PET) targeting the phosphodiesterase 10A enzyme (PDE10A). PDE10A is highly expressed in the striatum by medium spiny neurons, and it has been demonstrated to be involved in the regulation of striatal signaling through the reduction of medium spiny neuronal sensitivity towards glutamatergic(More)
Phosphodiesterase 10A (PDE10A) is a member of the PDE family of enzymes that degrades cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). Our aim was to label a series of structurally related PDE10A inhibitors with carbon-11 and evaluate them as potential positron emission tomography (PET) radioligands for PDE10A using nonhuman(More)
Fourteen airworthy men, aged 19-20 yrs., participated in the experiments aimed at studying a prognostic significance of biochemical and hormonal parameters in evaluation of human tolerance to acute hypoxic hypoxia. Altitude chamber experiments were performed to study the tolerance to hypoxia by "ascending" the test subjects to an altitude of 6 to 7 km. It(More)
A study was performed to find informative functional tests for assessing cerebrovascular reactivity. The effects of the hypoxic (breathing a gas mixture containing 10% O2), closed-loop rebreathing, voluntary hyperventilation, and Stange and Hench tests on the cerebral blood flow were compared. Doppler sonography was used to determine the linear velocity of(More)
BACKGROUND The neurotransmitter norepinephrine has been implicated in psychiatric and neurodegenerative disorders. Examination of synaptic norepinephrine concentrations in the living brain may be possible with positron emission tomography (PET), but has been hampered by the lack of suitable radioligands. METHODS We explored the use of the novel(More)
Interaction of piperazine-based dopamine transporter inhibitor GBR12909 with rat dopamine transporters has been studied by means of competition kinetics analysis, employing [(3)H]PE2I as the reporter ligand. It has been found that GBR12909 is capable of inducing so-called "slow isomerization step" upon binding to DAT, probably consisting of a conformational(More)
The kinetics of the association and dissociation of the tritium-labeled selective and potent dopamine transporter inhibitor N-(3-iodoprop-2E-enyl)-2beta-carbo-[3H]methoxy-3beta-(4'-methylphenyl)nortropane ([3H]PE2I) with the transporter of mouse striatal membranes was studied. The analysis revealed that the specific binding of [3H]PE2I occurs within a(More)