Muneyuki Sakata

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BACKGROUND Sigma-1 receptors might be implicated in the pathophysiology of psychiatric diseases, as well as in the mechanisms of action of some selective serotonin reuptake inhibitors (SSRIs). Among the several SSRIs, fluvoxamine has the highest affinity for sigma-1 receptors (Ki = 36 nM), whereas paroxetine shows low affinity (Ki = 1893 nM). The present(More)
OBJECTIVE To reduce variance of the total volume of distribution (V (T)) image, we improved likelihood estimation in graphical analysis (LEGA) for dynamic positron emission tomography (PET) images using maximum a posteriori (MAP). METHODS In our proposed MAP estimation in graphical analysis (MEGA), a set of time-activity curves (TACs) was formed with V(More)
The acetylcholinesterase (AChE) inhibitor donepezil is also a sigma1 receptor agonist. We examined whether donepezil binds to sigma1 receptors in the living human brain after a single oral administration. Dynamic positron emission tomography (PET) data acquisition using the selective sigma1 receptor ligand [11C]SA4503 was performed to evaluate(More)
Adenosine A(2A) receptors (A2ARs) are thought to interact negatively with the dopamine D(2) receptor (D2R), so selective A2AR antagonists have attracted attention as novel treatments for Parkinson's disease (PD). However, no information about the receptor in living patients with PD is available. The purpose of this study was to investigate the relationship(More)
Cerebral blood flow (CBF) during dynamic exercise has never been examined quantitatively using positron emission tomography (PET). This study investigated changes in CBF that occur over the course of a moderate, steady-state cycling exercise. Global and regional CBF (gCBF and rCBF, respectively) were measured using oxygen-15-labeled water (H(2)(15)O) and(More)
The objective of this study was to establish the kinetic analysis for mapping sigma(1) receptors (sigma1Rs) in the human brain by positron emission tomography (PET) with [(11)C]SA4503. The sigma1Rs are considered to be involved in various neurological and psychiatric diseases. [(11)C]SA4503 is a recently developed radioligand with high and selective(More)
The aim of this study was to investigate the effect of age on the distribution of adenosine A₁ receptors (A₁Rs) and adenosine A(2A) receptors (A(2A)Rs) in the striatum of healthy subjects using PET imaging with 8-dicyclopropylmethyl-1-[¹¹C]methyl-3-propylxanthine ([¹¹C]MPDX) and [7-methyl-¹¹C]-(E)-8-(3,4,5-trimethoxystyryl)-1,3,7-trimethylxanthine(More)
BACKGROUND The objective of this study was to investigate the relationship between normalized regional cerebral metabolic rates of glucose (normalized-rCMRglc) and gait function in physically and mentally high-functioning older women. METHODS One hundred eighty-two community-dwelling older women (mean age [SD], 69.4 [6.6] years) without disability in(More)
For evaluating a newly developed radioligand for positron emission tomography (PET), successive measurements of regional cerebral blood flow (rCBF) and the kinetics of the radioligand in the same subject are preferable in the first clinical trial. In this study, we demonstrate an example for the study of (11)C-labeled(More)
Sigma(1) receptors were imaged in living human brain by positron emission tomography (PET) using [(11)C] SA4503. A dynamic 90-min scan and kinetic analysis enabled quantification of receptor density in the brain. The sigma(1) receptors were distributed throughout the brain in normal subjects, but decreased in the frontal, temporal, and occipital lobes,(More)