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Visualizing the dynamics of cesium (Cs) is desirable to understand the impact of radiocesium when accidentally ingested or inhaled by humans. However, visualization of radiocesium in vivo is currently limited to plants. Herein, we describe a method for the production and purification of 127Cs and its use in visualizing Cs dynamics in a living animal. The positron-emitting nuclide 127Cs was produced using the 127I (α, 4n) 127Cs reaction, which was induced by irradiation of sodium iodide with a 4He2+ beam from a cyclotron. We excluded sodium ions by using a material that specifically adsorbs Cs as a purification column and successfully eluted 127Cs by flowing a solution of ammonium sulfate into the column. We injected the purified 127Cs tracer solution into living rats and the dynamics of Cs were visualized using positron emission tomography; the distributional images showed the same tendency as the results of previous studies using disruptive methods. Thus, this method is useful for the non-invasive investigation of radiocesium in a living animal.

Introduction: We aimed to determine whether in vivo tau deposits and monoamine oxidase B (MAO-B) detection using 18F-THK5351 positron emission tomography (PET) can assist in the differential distribution in patients with corticobasal syndrome (CBS), progressive supranuclear palsy (PSP), and Alzheimer’s disease (AD) and whether 18F-THK5351 retention of lesion sites in CBS and PSP can correlate with clinical parameters.Methods:18F-THK5351 PET was performed in 35 participants, including 7, 9, and 10 patients with CBS, PSP, and AD, respectively, and 9 age-matched normal controls. In CBS and PSP, cognitive and motor functions were assessed using the Montreal Cognitive Assessment, Addenbrooke’s Cognitive Examination–Revised, and Frontal Assessment Battery, Unified Parkinson’s Disease Rating Scale Motor Score, and PSP Rating Scale.Results:18F-THK5351 retention was observed in sites susceptible to disease-related pathologies in CBS, PSP, and AD. 18F-THK5351 uptake in the precentral gyrus clearly differentiated patients with CBS from those with PSP and AD. Furthermore, 18F-THK5351 uptake in the inferior temporal gyrus clearly differentiated patients with AD from those with CBS and PSP. Regional 18F-THK5351 retention was associated with the cognitive function in CBS and PSP.Conclusion: Measurement of the tau deposits and MAO-B density in the brain using 18F-THK5351 may be helpful for the differential diagnosis of tauopathies and for understanding disease stages.

Background and purpose Corticobasal syndrome (CBS) is pathologically characterized by tau deposits in neuronal and glial cells and by reactive astrogliosis. In several neurodegenerative disorders, 18 F-THK5351 has been observed to bind to reactive astrocytes expressing monoamine oxidase B. In this study, the aim was to investigate the progression of disease-related pathology in the brains of patients with CBS using positron emission tomography with 18 F-THK5351. Methods Baseline and 1-year follow-up imaging were acquired using magnetic resonance imaging and positron emission tomography with 18 F-THK5351 in 10 subjects: five patients with CBS and five age-matched normal controls (NCs). Results The 1-year follow-up scan images revealed that 18 F-THK5351 retention had significantly increased in the superior parietal gyrus of the patients with CBS compared with the NCs. The median increases in 18 F-THK5351 accumulation in the patients with CBS were 6.53% in the superior parietal gyrus, 4.34% in the precentral gyrus and 4.33% in the postcentral gyrus. In contrast, there was no significant increase in the regional 18 F-THK5351 retention in the NCs. Conclusions Longitudinal increases in 18 F-THK5351 binding can be detected over a short interval in the cortical sites of patients with CBS. A monoamine oxidase B binding radiotracer could be useful in monitoring the progression of astrogliosis in CBS.

Small animal PET provides the biodistribution of administrated radiotracer in vivo and have a potential to contribute on dosimetry study. The aim of this study is to investigate the effect of region-of-interest (ROI)-delineation in whole-body rat PET image toward non-invasive estimation of human dosimetry ofAfter administration ofAveraged effective doses ofThe use of small animal PET scanner, which allows repeatedly PET scans, have a potential to contribute on the reduction of the number of experimental animals. However, the ways of ROI drawing influences on the estimated effective dose and safe-side ROI definition may be preferred.

This study aimed to examine the dynamic change in bone metabolism by immediate loading in several sites around implants using high-resolution Na18F-PET scan. Two titanium implants (O 1.2 mm) were inserted parallel to each other in the right tibiae of Wistar rats (n = 4). The left tibia was set as control side. One day after insertion, closed coil springs of 4.0 N were attached to the expose superior portions of the implants to apply a continuous mechanical stress. The rats with fluorine-18 (18F) ion (5 mCi/rat) intravenously injected were scanned by PET scanner at 4, 7, 14, 28 days after load application. Round region of interests (ROIs) were set around the distal implant of the right tibia (loaded side) and same site (control) of the left tibia. Furthermore, four rectangular ROIs were set at the superior and inferior parts of traction side (mesial) and opposite side (distal) of the distal implant. Longitudinal dynamic changes in bone metabolism were evaluated by examination of the accumulation count of 18F ion at each ROI. The uptake values of ROIs (loaded side) initially increased until 7 days, and they gradually decreased from the peak level to the pre-loading level despite a static force being applied to the implants. In cancellous bone, the uptake values at the superior part of traction side and inferior part of opposite side showed significantly high value compared with those at other parts. In conclusion, immediate loading to the implant initially enhanced bone metabolism around it, especially at the part with compressive stress. Peri-implant bone metabolism varies according to different loading conditions.

Objective— Drug-eluting stent–induced coronary hyperconstricting responses remain an important issue. The adventitia harbors a variety of components that potently modulate vascular tone, including sympathetic nerve fibers (SNF) and vasa vasorum. Catheter-based renal denervation (RDN) inhibits sympathetic nerve activity. We, thus, examined whether RDN suppresses drug-eluting stent–induced coronary hyperconstricting responses, and if so, what mechanisms are involved. Approach and Results— Protocol 1: pigs implanted with everolimus-eluting stents into the left coronary arteries underwent coronary angiography at 1 month after implantation for assessment of coronary vasomotion and adventitial SNF formation. Drug-eluting stent–induced coronary hyperconstricting responses were significantly enhanced associated with enhanced coronary adventitial SNF and vasa vasorum formation. Protocol 2: pigs implanted with everolimus-eluting stents were randomly assigned to the RDN or sham group. The RDN group underwent renal ablation. At 1 month, RDN significantly caused marked damage of the SNF at the renal arteries without any stenosis, thrombus, or dissections. Notably, RDN significantly upregulated the expression of α 2 -adrenergic receptor–binding sites in the nucleus tractus solitarius, attenuated muscle sympathetic nerve activity, and decreased systolic blood pressure and plasma renin activity. In addition, RDN attenuated coronary hyperconstricting responses to intracoronary serotonin at the proximal and distal stent edges associated with decreases in SNF and vasa vasorum formation, inflammatory cell infiltration, and Rho-kinase expression/activation. Furthermore, there were significant positive correlations between SNF and vasa vasorum and between SNF and coronary vasoconstricting responses. Conclusions— These results provide the first evidence that RDN ameliorates drug-eluting stent–induced coronary hyperconstricting responses in pigs in vivo through the kidney–brain–heart axis.

Objective— Although coronary perivascular adipose tissue (PVAT) may play important roles as a source of inflammation, the association of coronary PVAT inflammation and coronary hyperconstricting responses remains to be examined. We addressed this important issue in a porcine model of coronary hyperconstricting responses after drug-eluting stent implantation with 18 F-fluorodeoxyglucose ( 18 F-FDG) positron emission tomographic imaging. Approach and Results— An everolimus-eluting stent (EES) was randomly implanted in pigs into the left anterior descending or the left circumflex coronary artery while nonstented coronary artery was used as a control. After 1 month, coronary vasoconstricting responses to intracoronary serotonin (10 and 100 μg/kg) were examined by coronary angiography in vivo, followed by in vivo and ex vivo 18 F-FDG positron emission tomographic/computed tomographic imaging. Coronary vasoconstricting responses to serotonin were significantly enhanced at the EES edges compared with the control site ( P 18 F-FDG positron emission tomographic/computed tomographic imaging and autoradiography showed enhanced 18 F-FDG uptake and its accumulation in PVAT at the EES edges compared with the control site, respectively (both P P Conclusions— These results indicate for the first time that inflammatory changes of coronary PVAT are associated with drug-eluting stent–induced coronary hyperconstricting responses in pigs in vivo and that 18 F-FDG positron emission tomographic imaging is useful for assessment of coronary PVAT inflammation.

Clinical PET studies using 18F-THK5351 have demonstrated significant tracer retention in sites susceptible to tau burden in Alzheimer disease (AD). However, the in vivo PET signal to reflect tau aggregates remains controversial. Methods: We examined the spatial pattern of tracer binding, amyloid-β, tau, and gliosis in an autopsy-confirmed AD patient who underwent 18F-THK5351 and 11C-Pittsburgh compound B PET before death. Results: Regional in vivo 18F-THK5351 retention was significantly correlated with the density of tau aggregates in the neocortex and monoamine oxidase-B in the whole brain, but not correlated with that of insoluble amyloid-β. Furthermore, significant association was observed between the density of tau aggregates, monoamine oxidase-B, and glial fibrillary acidic protein, suggesting that neocortical tau would strongly influence the formation of reactive astrocytes. Conclusion:18F-THK5351 PET may have limited utility as a biomarker of tau pathology in AD; however, it could be used to monitor the neuroinflammatory processes in the living brain.

Moving a patient between a bed and a wheel-chair is one of the most burdensome nursing-care tasks for caregivers. Various kinds of transfer assistant robots have been proposed previously. However, designing comfortable transfer motions for individuals has not been intensively studied due to the difficulty of modeling such physical human-robot interactions in conjunction with user preference. To lift a patient from a bed, a robot should raise the patient’s body from the supine posture to a holding posture. In this research, we proposed two different methods for generating lifting motions comfortable for users: (1) a model-based method for estimating the holding posture, and (2) a model-free method based on Bayesian optimization for generating the raising motion. A comfortable holding posture can be generated using human-robot interactive models by reducing the load and pain sensation in simulation, without user trials. To reduce the load, a musculoskeletal model is developed to estimate muscle force considering human-robot physical interactions. To reduce pain, a softness distribution model of the human body is also created to control the robot to contact the human body at a softer place. The motion for raising the human body from the supine posture to the estimated holding posture can be generated with the model-free method from the user’s feedback (scalar value) in terms of the comfort level. Using Bayesian optimization, the number of required trials with physical interactions between user and robot can be reduced to ease the user’s burden. To verify the effectiveness of the proposed methods, we conducted experiments with a dual arm robotic system and human subjects. We search for the most comfortable holding posture based on the developed human models and compare it with the measured value of subjects in the experiment. To generate the raising motion, the experimental result shows that our method can optimize a user-comfortable care motion controller for each individual efficiently.

Some histamine H1 receptor (H1R) antagonists induce adverse sedative reactions caused by blockade of histamine transmission in the brain. Desloratadine is a second‐generation antihistamine for treatment of allergic disorders. Its binding to brain H1Rs, which is the basis of sedative property of antihistamines, has not been examined previously in the human brain by positron emission tomography (PET). We examined brain H1R binding potential ratio (BPR), H1R occupancy (H1RO), and subjective sleepiness after oral desloratadine administration in comparison to loratadine. Eight healthy male volunteers underwent PET imaging with [11C]‐doxepin, a PET tracer for H1Rs, after a single oral administration of desloratadine (5 mg), loratadine (10 mg), or placebo in a double‐blind crossover study. BPR and H1RO in the cerebral cortex were calculated, and plasma concentrations of loratadine and desloratadine were measured. Subjective sleepiness was quantified by the Line Analogue Rating Scale (LARS) and the Stanford Sleepiness Scale (SSS). BPR was significantly lower after loratadine administration than after placebo (0.504 ± 0.074 vs 0.584 ± 0.059 [mean ± SD], P

Visualizing the dynamics of cesium (Cs) is desirable to understand the impact of radiocesium when accidentally ingested or inhaled by humans. However, visualization of radiocesium in vivo is currently limited to plants. Herein, we describe a method for the production and purification of 127Cs and its use in visualizing Cs dynamics in a living animal. The positron-emitting nuclide 127Cs was produced using the 127I (α, 4n) 127Cs reaction, which was induced by irradiation of sodium iodide with a 4He2+ beam from a cyclotron. We excluded sodium ions by using a material that specifically adsorbs Cs as a purification column and successfully eluted 127Cs by flowing a solution of ammonium sulfate into the column. We injected the purified 127Cs tracer solution into living rats and the dynamics of Cs were visualized using positron emission tomography; the distributional images showed the same tendency as the results of previous studies using disruptive methods. Thus, this method is useful for the non-invasive investigation of radiocesium in a living animal.

Recent positron emission tomography (PET) studies have demonstrated the accumulation of tau PET tracer in the affected region of progressive supranuclear palsy (PSP) cases. To confirm the binding target of radiotracer in PSP, we performed an imaging-pathology correlation study in two autopsy-confirmed PSP patients who underwent [18F]THK5351 PET before death. One patient with PSP Richardson syndrome showed elevated tracer retention in the globus pallidus and midbrain. In a patient with PSP-progressive nonfluent aphasia, [18F]THK5351 retention also was observed in the cortical areas, particularly the temporal cortex. Neuropathological examination confirmed PSP in both patients. Regional [18F]THK5351 standardized uptake value ratio (SUVR) in antemortem PET was significantly correlated with monoamine oxidase-B (MAO-B) level, reactive astrocytes density, and tau pathology at postmortem examination. In in vitro autoradiography, specific THK5351 binding was detected in the area of antemortem [18F]THK5351 retention, and binding was blocked completely by a reversible selective MAO-B inhibitor, lazabemide, in brain samples from these patients. In conclusion, [18F]THK5351 PET signals reflect MAO-B expressing reactive astrocytes, which may be associated with tau accumulation in PSP.

Recent positron emission tomography (PET) studies have demonstrated the accumulation of tau PET tracer in the affected region of progressive supranuclear palsy (PSP) cases. To confirm the binding target of radiotracer in PSP, we performed an imaging-pathology correlation study in two autopsy-confirmed PSP patients who underwent [18F]THK5351 PET before death. One patient with PSP Richardson syndrome showed elevated tracer retention in the globus pallidus and midbrain. In a patient with PSP-progressive nonfluent aphasia, [18F]THK5351 retention also was observed in the cortical areas, particularly the temporal cortex. Neuropathological examination confirmed PSP in both patients. Regional [18F]THK5351 standardized uptake value ratio (SUVR) in antemortem PET was significantly correlated with monoamine oxidase-B (MAO-B) level, reactive astrocytes density, and tau pathology at postmortem examination. In in vitro autoradiography, specific THK5351 binding was detected in the area of antemortem [18F]THK5351 retention, and binding was blocked completely by a reversible selective MAO-B inhibitor, lazabemide, in brain samples from these patients. In conclusion, [18F]THK5351 PET signals reflect MAO-B expressing reactive astrocytes, which may be associated with tau accumulation in PSP. Electronic supplementary material The online version of this article (10.1186/s40478-018-0556-7) contains supplementary material, which is available to authorized users.

Visualization of the spatial distribution of neurofibrillary tangles would help in the diagnosis, prevention and treatment of dementia. The purpose of the study was to evaluate the clinical utility of [(18)F]THK-5117 as a highly selective tau imaging radiotracer.We initially evaluated in vitro binding of [(3)H]THK-5117 in post-mortem brain tissues from patients with Alzheimer's disease (AD). In clinical PET studies, [(18)F]THK-5117 retention in eight patients with AD was compared with that in six healthy elderly controls. Ten subjects underwent an additional [(11)C]PiB PET scan within 2 weeks.In post-mortem brain samples, THK-5117 bound selectively to neurofibrillary deposits, which differed from the binding target of PiB. In clinical PET studies, [(18)F]THK-5117 binding in the temporal lobe clearly distinguished patients with AD from healthy elderly subjects. Compared with [(11)C]PiB, [(18)F]THK-5117 retention was higher in the medial temporal cortex.These findings suggest that [(18)F]THK-5117 provides regional information on neurofibrillary pathology in living subjects.

Clinical PET studies using

Although coronary perivascular adipose tissue (PVAT) may play important roles as a source of inflammation, the association of coronary PVAT inflammation and coronary hyperconstricting responses remains to be examined. We addressed this important issue in a porcine model of coronary hyperconstricting responses after drug-eluting stent implantation withAn everolimus-eluting stent (EES) was randomly implanted in pigs into the left anterior descending or the left circumflex coronary artery while nonstented coronary artery was used as a control. After 1 month, coronary vasoconstricting responses to intracoronary serotonin (10 and 100 μg/kg) were examined by coronary angiography in vivo, followed by in vivo and ex vivoThese results indicate for the first time that inflammatory changes of coronary PVAT are associated with drug-eluting stent-induced coronary hyperconstricting responses in pigs in vivo and that

This study aimed to examine the dynamic change in bone metabolism by immediate loading in several sites around implants using high-resolution Na

We report an elemental analysis of murine solid tumors treated with cisplatin-incorporated polymeric micelles (NC-6004) to evaluate the concentration of the drug in the tumor tissue using conventional particle-induced X-ray emission (PIXE) analysis, as well as the spatial distribution in the tumor section using sub-millimeter PIXE analysis. The results reveal that the platinum concentration in the tumor treated with NC-6004 was higher than in that treated with cisplatin, whereas no significant difference was found in platinum concentration between NC-6004 and cisplatin samples in the normal tissue. This suggests that NC-6004 can both provide therapeutic efficacy and reduce the side effects caused by conventional treatment using cisplatin. These results show that PIXE analysis is a powerful tool for research into drug delivery systems.

The effects of the vascular disrupting agent AVE8062 on tumor and normal tissue samples were investigated by particle-induced X-ray emission (PIXE) analysis using quantum dots (QDs). We investigated fibrosarcoma tumors in mice, and used kidney tissue as a control. Non-targeted QDs were used to characterize the tissue regions where blood flow is interrupted by AVE8062. We found that the concentration of the QDs in the tumors and kidneys exposed to AVE8062 was lower than that of the control group. Sub-millimeter PIXE analysis (with a beam size of 0.5 [Formula: see text] 0.5 mm2) was used to investigate the spatial distribution of QDs in the tissue samples. We found that the QDs were accumulated in localized regions of the kidney section of the AVE8062-treated group whereas the QDs were uniformly distributed in the control kidney. This suggests that AVE8062 caused blood flow interruption not only in the tumor samples but also in the normal blood vessels in the kidneys.

Histamine H1 antagonists have hypnotic, appetite-promoting, and sedative effects. The affinities of various antidepressants for histamine receptors have only been partially determined in vitro and animal study. Positron emission tomography (PET) can clarify the in vivo dynamics of antidepressants at histamine receptors. We performed human PET imaging with [11C]doxepin, a selective PET ligand of the histamine H1 receptor (H1R), to study the in vivo affinities of fluvoxamine and mirtazapine for the H1R. The subjects were five male healthy Japanese volunteers. We performed cross-randomized PET imaging after single oral administration of fluvoxamine (25 mg), mirtazapine (15 mg), or placebo. PET data were analyzed by region-of-interest and voxel-by-voxel analysis. We concurrently measured plasma drug concentrations, using liquid chromatography/tandem mass spectrometry and subjective sleepiness. The binding potential ratio of mirtazapine in brain cortex was significantly lower than that of fluvoxamine or placebo. Fluvoxamine did not occupy the H1R, whereas H1R occupancy (H1RO) of mirtazapine reached 80–90 % in the cerebral neocortex. In the voxel-by-voxel analysis, the binding potential of mirtazapine was significantly lower than placebo in the dorsolateral prefrontal cortex, lateral temporal cortex, anterior cingulate gyrus, and posterior cingulate gyrus. The H1RO of mirtazapine depended on the plasma drug concentration (AUC0–180 min) and was related to subjective sleepiness. Our results demonstrate a low affinity of fluvoxamine and a very high affinity of mirtazapine for the human brain H1R in vivo. This study provides a basis for investigating the efficacy of new-generation antidepressants in central histamine systems.

Objective:To determine whether 18F-THK5351 PET can be used to visualize tau deposits in brain lesions in live patients with corticobasal syndrome (CBS).Methods:We evaluated the in vitro binding of 3H-THK5351 in postmortem brain tissues from a patient with corticobasal degeneration (CBD). In clinical PET studies, 18F-THK5351 retention in 5 patients with CBS was compared to that in 8 age-matched normal controls and 8 patients with Alzheimer disease (AD).Results:3H-THK5351 was able to bind to tau deposits in the postmortem brain with CBD. In clinical PET studies, the 5 patients with CBS showed significantly higher 18F-THK5351 retention in the frontal, parietal, and globus pallidus than the 8 age-matched normal controls and patients with AD. Higher 18F-THK5351 retention was observed contralaterally to the side associated with greater cortical dysfunction and parkinsonism.Conclusions:18F-THK5351 PET demonstrated high tracer signal in sites susceptible to tau deposition in patients with CBS. 18F-THK5351 should be considered as a promising candidate radiotracer for the in vivo imaging of tau deposits in CBS.

Transferring is one of care motions for transferring a patient between a bed and a wheelchair, which is a heavy burden task for caregivers. Various kinds of transferring assistant robots have been proposed previously. However, designing comfortable transfer motions for individuals has not been intensively studied maybe due to its difficulty in modeling of such physical human-robot interactions and user's preference. In this paper, we propose a novel framework for generating comfortable transfer motion for individuals. We find the comfortable motion from the user feedback (scalar value) through human-robot physical interactions. To make such an approach practical, it is critical to reduce the number of required experiments with physical interactions between the user and the robot for reducing user's burden. We formulate the task as a black-box optimization problem of a unknown noisy function; Bayesian optimization, a data-efficient black-box optimization method, is utilized for quickly searching the optimal care motion. In our experiment, a dual-arm human transfer assistant robot is used for the raising upper body task in lift-up state. Experimental results demonstrate that our method can optimize a user-comfortable care motion controller for each individual efficiently. Moreover, the relationship between the user feedback and the sensor data associated with the robot care motions are analyzed using linear regression analysis.

To separate (90)Y from the fission product (90)Sr-(90)Y group, a silica-based TODGA/SiO(2)-P adsorbent was prepared by impregnating N,N,N',N'-tetraoctyl-3-oxapentane-1,5-diamide (TODGA) extractant into the macroporous SiO(2)-P support with a mean diameter of 60 μm. The adsorption behavior of Sr(II) and Y(III) onto TODGA/SiO(2)-P adsorbent from HNO(3) solution and their mutual separation were investigated. Under the experimental conditions, this adsorbent showed high adsorption affinity to Y(III) and weak adsorption to Sr(II). It was found that the adsorption process of Y(III) could be expressed by both of Langmuir monomolecular layer adsorption mode and the pseudo-second order model. From the results of stability experiments, it became clear that TODGA/SiO(2)-P adsorbent is stable in 3M HNO(3) solution for 1 month contact time at 298 K. Using a column packed with TODGA/SiO(2)-P adsorbent, Sr(II) and Y(III) were eluted by distilled water and diethylenetriamine pentaacetic acid (DTPA) solution, respectively. The separation of Y(III) from Sr(II)-Y(III) group was achieved successfully.

The aim of the study was to predict donepezil responders among patients with Alzheimer disease (AD) based on cognitive tests and positron emission tomography. The Mini-Mental State Examination, Digit Symbol subtest (DigSm) of Wechsler Adult Intelligence Scale Revised, and Trail-Making Test A were administered for 80 patients with AD to assess global function, attention, and executive function, respectively. The same tests and the Clinical Global Impression (CGI) scale were conducted after treatment with oral donepezil (5 mg/d) for 6 months (study 1). [C]-Donepezil positron emission tomography examinations were conducted before and after treatment for 30 randomly selected patients. The distribution volume (DV), which indicates the density of donepezil-binding sites, was calculated using Logan graphical analysis (study 2). In study 1, 35 patients were identified as responders based on the CGI and Mini-Mental State Examination changes. These patients had higher baseline DigSm scores compared with nonresponders. In study 2, 15 patients were responders. DigSm correlated with DV at baseline. DV at baseline and %DV change in responders were higher than in nonresponders, and these variables correlated with ΔDigSm and CGI scores. Higher baseline attention may predict responsiveness to donepezil in patients with AD, and higher acetylcholinesterase levels result in a greater clinical effect.

Platinum concentration in a murine solid tumor treated with proton therapy combined with the platinum-based chemotherapeutic agent cisplatin [cis-diamminedichloro-platinum(II) (CDDP)] was investigated with conventional and submilli-PIXE (particle-induced X-ray emission) analyses. An enhanced therapeutic effect on tumor growth was observed in NFSa fibrosarcoma tumors in mice when proton therapy with a single dose of 30 Gy and CDDP treatment (10 mg/kg) were combined. The conventional PIXE analysis based on an internal standard method showed that the platinum concentration was 2.6 ± 0.3 µg/g for the tumor samples excised from the mice 6 h after the CDDP administration. The submilli-PIXE analysis of the tumor sections showed that spatial distribution of CDDP may be more or less uniform in the tumor. Copyright © 2011 John Wiley & Sons, Ltd.

Spatial distributions of principal elements in a NFSa fibrosarcoma tumor treated with a vascular disruption agent, AVE8062 (a derivative of combretastatin A-4) at a single dose of 40 mg/kg were evaluated on the basis of particle-induced X-ray emission (PIXE) analysis using a submillimeter-sized proton beam. We found not only potassium and sulfur concentrations at the periphery of the treated tumor but also a ring-shaped calcium distribution in the area between the inner necrotic region and the periphery. These observations were supported by results for quantitative evaluation of elemental concentrations in the tumor samples obtained from conventional PIXE analysis based on the internal standard method. It is suggested that the potassium and sulfur concentrations are related to residual viable cells at the tumor periphery which are commonly observed in VDA treatments whereas the ring of calcium concentration just inside the tumor periphery is possibly derived from hypoxia-induced response.

The development of nonviral gene delivery systems is essential in gene therapy, and the use of a minimally invasive imaging methodology can provide important clinical endpoints. In the current study, we present a new methodology for gene therapy—a delivery system using nanobubbles and ultrasound as a nonviral gene delivery method. We assessed whether the gene transfer allowed by this methodology was detectable by PET and bioluminescence imaging. Methods: Two kinds of reported vectors (luciferase and human Na/I symporter [hNIS]) were transfected or cotransfected into the skeletal muscles of normal mice (BALB/c) using the ultrasound–nanobubbles method. The kinetics of luciferase gene expression were analyzed in vivo using bioluminescence imaging. At the peak of gene transfer, PET of hNIS expression was performed using our recently developed PET scanner, after 124I injection. The imaging data were confirmed using reverse-transcriptase polymerase chain reaction amplification, biodistribution, and a blocking study. The imaging potential of the 2 methodologies was evaluated in 2 mouse models of human pathology (McH/lpr-RA1 mice showing vascular disease and C57BL/10-mdx Jic mice showing muscular dystrophy). Results: Peak luciferase gene activity was observed in the skeletal muscle 4 d after transfection. On day 2 after hNIS and luciferase cotransfection, the expression of these genes was confirmed by reverse-transcriptase polymerase chain reaction on a muscle biopsy. PET of the hNIS gene, biodistribution, the blocking study, and autoradiography were performed on day 4 after transfection, and it was indicated that hNIS expression was restricted to the site of plasmid administration (skeletal muscle). Similar localized PET and 124I accumulation were successfully obtained in the disease-model mice. Conclusion: The hNIS gene was delivered into the skeletal muscle of healthy and disease-model mice by the ultrasound–nanobubbles method, and gene expression was successfully visualized with PET. The combination of ultrasound–nanobubble gene transfer and PET may be applied to gene therapy clinical protocols.

The histopathological hallmark of multiple system atrophy is the appearance of intracellular inclusion bodies, named glial cytoplasmic inclusions, which are mainly composed of alpha-synuclein fibrils. In vivo visualization of alpha-synuclein deposition should be used for the diagnosis and assessment of therapy and severity of pathological progression in multiple system atrophy. Because 2-[2-(2-dimethylaminothiazol-5-yl)ethenyl]-6-[2-(fluoro)ethoxy] benzoxazole could stain alpha-synuclein-containing glial cytoplasmic inclusions in post-mortem brains, we compared the carbon-11-labelled 2-[2-(2-dimethylaminothiazol-5-yl)ethenyl]-6-[2-(fluoro)ethoxy] benzoxazole positron emission tomography findings of eight multiple system atrophy cases to those of age-matched normal controls. The positron emission tomography data demonstrated high distribution volumes in the subcortical white matter (uncorrected P < 0.001), putamen and posterior cingulate cortex (uncorrected P < 0.005), globus pallidus, primary motor cortex and anterior cingulate cortex (uncorrected P < 0.01), and substantia nigra (uncorrected P < 0.05) in multiple system atrophy cases compared to the normal controls. They were coincident with glial cytoplasmic inclusion-rich brain areas in multiple system atrophy and thus, carbon-11-labelled 2-[2-(2-dimethylaminothiazol-5-yl)ethenyl]-6-[2-(fluoro)ethoxy] benzoxazole positron emission tomography is a promising surrogate marker for monitoring intracellular alpha-synuclein deposition in living brains.

Concentrations of the chemotherapeutic agent, cis-diamminedichloro-platinum(II) (CDDP) in NFSa fibrosarcoma tumors were investigated using a conventional PIXE analysis on the basis of an internal standard method to study enhancement of antitumor effects caused by proton therapy combined with CDDP treatment. Results of the PIXE analysis showed that platinum concentration of the tumors treated with CDDP at a single dose of 10 mg/kg was 2.0±0.1 µg/g and persisted at the level at least 6 hours after the administration. The present study demonstrated that the presence of CDDP in the tumor caused an enhanced therapeutic effect on tumor growth delay when CDDP treatment was combined with post proton-irradiation in comparison with CDDP treatment alone or proton therapy alone.

Two techniques employed for the early diagnosis of dementia are the imaging of amyloid-beta protein using positron emission tomography (PET) and voxel-based morphometry analysis of MRI (VBM-MRI). The purpose of this study was to evaluate the clinical utility of amyloid PET and VBM-MRI for the early diagnosis and tracking of the severity of Alzheimer's disease (AD). The neuritic plaque burden and gray matter losses were evaluated using [11C]BF-227-PET and VBM-MRI in 12 healthy controls, 13 subjects with mild cognitive impairment (MCI), including 6 who converted to AD and 7 who did not convert, and 15 AD patients. The AD patients and the MCI converters exhibited a neocortical retention of BF-227 and parahippocampal gray matter loss shown by VBM-MRI. The MCI converters were more clearly distinguished from the MCI non-converters in BF-227-PET than VBM-MRI. The combined sample of the MCI converters and AD patients showed a significant correlation of MMSE scores with the global gray matter loss, but not with the BF-227 retention. These findings suggest that amyloid PET using [11C]BF-227 is better suited for the prediction of conversion from MCI to AD, while VBM-MRI appears to be better suited for tracking the severity of dementia.

Aims The strength of sedation due to antihistamines can be evaluated using positron emission tomography (PET). The purpose of the present study is to measure histamine H1 receptor (H1R) occupancy following oral administration of cetirizine (10 and 20 mg) in order to examine dose dependency. Methods Fifteen healthy male volunteers (age range, 20–35 years) were divided into 3 subgroups and were studied following single oral administration of cetirizine at 10 mg (n = 5) and 20 mg (n = 5) or hydroxyzine at 30 mg (n = 5) using PET with 11C-doxepin. Each subject was scanned also following the administration of placebo. Binding potential and H1RO values were calculated in the prefrontal and anterior cingulate cortices. Subjective sleepiness was also measured, and the correlation to H1RO was examined for each antihistamine. Results The averaged H1ROs of cetirizine 10 mg, 20 mg, and hydroxyzine 30 mg in the prefrontal and cingulate cortices was 12.6%, 25.2%, and 67.6%, respectively. The H1RO of hydroxyzine 30 mg correlated well with subjective sleepiness (p

The aim of this study was to establish kinetic analysis of [5-(11)C-methoxy]donepezil ([(11)C]donepezil), which was developed for the in-vivo visualization of donepezil binding to acetylcholinesterase (AChE) using positron emission tomography (PET). Donepezil is an AChE inhibitor that is widely prescribed to ameliorate the cognitive impairment of patients with dementia. Six healthy subjects took part in a dynamic study involving a 60-min PET scan after intravenous injection of [(11)C]donepezil. The total distribution volume (tDV) of [(11)C]donepezil was quantified by compartmental kinetic analysis and Logan graphical analysis. A one-tissue compartment model (1TCM) and a two-tissue compartment model (2TCM) were applied in the kinetic analysis. Goodness of fit was assessed with chi(2) criterion and Akaike's Information Criterion (AIC). Compared with a 1TCM, goodness of fit was significantly improved by a 2TCM. The tDVs provided by Logan graphical analysis were slightly lower than those provided by a 2TCM. The rank order of the mean tDVs in 10 regions was in line with the AChE activity reported in a previous post-mortem study. Logan graphical analysis generated voxel-wise images of tDV, revealing the overall distribution pattern of AChE in individual brains. Significant correlation was observed between tDVs calculated with and without metabolite correction for plasma time-activity curves, indicating that metabolite correction could be omitted. In conclusion, this method enables quantitative analysis of AChE and direct investigation of the pharmacokinetics of donepezil in the human brain.

What is already known about this subject • Deficit in central cholinergic neurotransmission is a consistent change associated with Alzheimer's disease (AD). • Donepezil hydrochloride exhibits selective inhibition of acetylcholinesterase (AChE) and is widely used for the treatment of AD. • The biodistribution of donepezil in the brain after administration is not precisely understood in vivo. • There is no method to measure the amount of binding of orally administered donepezil to AChE. What this study adds • This study clearly visualizes the distribution of donepezil in human brain using [11C]-donepezil and positron emission tomography. • This study demonstrates prominent reduction of the donepezil binding site in the AD brain. • This study provides methodology to measure the AChE binding occupancy of orally administered donepezil and provides a new surrogate marker for evaluation and prediction of response to donepezil treatment. Aims The aims of this study were to visualize in vivo binding of donepezil to acetylcholinesterase (AChE) in the brain and to establish a method for measuring the amount of binding of orally administered donepezil. Methods [5-11C-methoxy]-donepezil ([11C]-donepezil) was radiolabelled as a positron emission tomography (PET) tracer. The biodistribution of [11C]-donepezil was measured by PET in 10 AD patients and six elderly normal subjects. Two AD patients underwent additional PET measurements after oral administration of donepezil for 6 months. Results [11C]-donepezil-PET images demonstrated high densities of tracer distribution in AChE-rich brain regions such as the striatum, thalamus, and cerebellum. Compared with elderly normal subjects, patients with mild AD exhibited about 18–20% reduction of donepezil binding in the neocortex and hippocampus, while patients with moderate AD exhibited about 24–30% reduction of donepezil binding throughout the brain. Orally administered donepezil (5 mg day−1) induced 61.6–63.3% reduction of donepezil binding in AD brains. The distribution volume of [11C]-donepezil in the hippocampus was significantly correlated with MMSE scores in AD patients. Conclusions [11C]-donepezil-PET enables quantitative measurement of donepezil binding in the brain. AD patients exhibited reduction of donepezil binding in the brain, even in the early stage of disease. Longitudinal evaluation by this technique enables determination of AChE binding occupancy of orally administered donepezil.

Background: In vivo detection of amyloid deposits in the brain is potentially useful for early diagnosis of Alzheimer's disease (AD) and tracking the efficacy of anti-amyloid therapy. Methods: To develop an amyloid-binding agent for positron emission tomography, we screened over 2600 compounds. Results: We found benzoxazole derivatives as candidate compounds for in vivo amyloid imaging probes. One of these agents, 2-(2-[2-dimethylaminothiazol-5-yl]ethenyl)-6-(2-[fluoro]ethoxy)benzoxazole (BF-227), displays high binding affinity to Aβ fibrils. BF-227 binding increased linearly with increasing Aβ fibril formation. In temporal and hippocampal AD brain sections, BF-227 selectively bound to amyloid plaques. In contrast, no staining was evident in the cerebellum. Compared with the previously reported compound BF-168, 18F-labeled BF-227 displayed selective in vivo labeling of amyloid fibrils and rapid washout from white matter areas in an Aβ-injected rat model. An acute and subacute toxicity study of BF-227 indicated sufficient safety for clinical use as a positron emission tomography probe. Conclusions: These findings suggest that BF-227 is feasible as an in vivo imaging probe of amyloid deposits in AD patients.

An animal PET scanner using CdTe detectors was developed for the purpose of biomedical study using mice and rats. A spatial resolution of 0.8 mm FWHM within the central 20 mm-diameter of the field of view (FOV) was obtained by small CdTe elements of 1.1 mm×5.0 mm×1.0 mm. This spatial resolution is the first achievement of a practical semiconductor animal PET scanner. The determination of the depth of the γ interaction in the detector was carried out by the use of two detector layers. The FOV is 64 mm in diameter and 26 mm in axis. Fine [ 18 F]FDG images of the heads of a mouse and a rat, where the cerebral cortex, the gray matter and the corpus striatum could be respectively distinguished, were successfully obtained. This work inspires the dawn of the high resolution semiconductor PET scanner age as the next generation.

The formation of neurofibrillary tangles is believed to contribute to the neurodegeneration observed in Alzheimer's disease (AD). Postmortem studies have shown strong associations between the neurofibrillary pathology and both neuronal loss and the severity of cognitive impairment. However, the temporal changes in the neurofibrillary pathology and its association with the progression of the disease are not well understood. Tau positron emission tomography (PET) imaging is expected to be useful for the longitudinal assessment of neurofibrillary pathology in the living brain. Here, we performed a longitudinal PET study using the tau-selective PET tracer [18F]THK-5117 in patients with AD and in healthy control subjects. Annual changes in [18F]THK-5117 binding were significantly elevated in the middle and inferior temporal gyri and in the fusiform gyrus of patients with AD. Compared to patients with mild AD, patients with moderate AD showed greater changes in the tau load that were more widely distributed across the cortical regions. Furthermore, a significant correlation was observed between the annual changes in cognitive decline and regional [18F]THK-5117 binding. These results suggest that the cognitive decline observed in patients with AD is attributable to the progression of neurofibrillary pathology. Longitudinal assessment of tau pathology will contribute to the assessment of disease progression and treatment efficacy.

Histamine H1 antagonists have hypnotic, appetite-promoting, and sedative side effects. Most second-generation antipsychotics have potent antagonistic effects on histamine H1 receptor (H1R). Positron emission tomography (PET) can measure the H1R occupancy (H1RO) in vivo, although there are no reports regarding antipsychotics. We studied the H1RO of olanzapine and quetiapine in vivo with respect to their plasma concentrations and subjective drowsiness by performing human PET imaging studies with [11C]doxepin, a potent PET ligand of H1R. Six healthy Japanese male volunteers were enrolled. Cross-randomized PET imaging was performed after a single oral administration of olanzapine (2.5 mg), quetiapine (25 mg), or placebo. PET data were analyzed by region of interest and voxel-by-voxel analysis. We concurrently measured plasma drug concentrations by liquid chromatography/tandem mass spectrometry and evaluated subjective sleepiness. The binding potential ratios of olanzapine and quetiapine in the cerebral cortex were significantly lower than that of the placebo. The H1RO values of olanzapine and quetiapine in the cortex were approximately 61–80 and 56–81 %, respectively. The binding potential ratios of the drugs were significantly lower than that of the placebo in the dorsolateral prefrontal and lateral temporal cortices, and anterior and posterior cingulate gyri. The H1RO values in the cortex were significantly correlated with subjective sleepiness but not plasma drug concentrations. Olanzapine and quetiapine have high H1RO values in the human brain under their clinical minimum doses. This study provides a foundation of the properties by which new-generation antipsychotics block the central histaminergic system in humans.

The purpose of this study was to compare two amyloid imaging agents, [(11)C]BF227 and [(18)F]FACT (derivative from [(11)C]BF227) through quantitative pharmacokinetics analysis in human brain.Positron emission tomography studies were performed on six elderly healthy control (HC) subjects and seven probable Alzheimer's disease (AD) patients with [(11)C]BF227 and 10 HC subjects and 10 probable AD patients with [(18)F]FACT. Data from nine regions of interest were analyzed by several approaches, namely non-linear least-squared fitting methods with arterial input functions (one-tissue compartment model(1TCM), two-tissue compartment model (2TCM)), Logan plot, and linearized methods with reference region (Reference Logan plot (RefLogan), MRTM0, MRTM2). We also evaluated SUV and SUVR for both tracers. The parameters estimated by several approaches were compared between two tracers for detectability of differences between HC and AD patients.For [(11)C]BF227, there were no significant difference of VT (2TCM, 1TCM) and SUV in all regions (Student t-test; p0.05) and significant differences in the DVRs (Logan, RefLogan, and MRTM2) and SUVRs in six neocortical regions (p0.05) between the HC and AD groups. For [(18)F]FACT, significant differences in DVRs (RefLogan, MRTM0, and MRTM2) were observed in more than four neocortical regions between the HC and AD groups (p0.05), and the significant differences were found in SUVRs for two neocortical regions (inferior frontal coretex and lateral temporal coretex). Our results showed that both tracers can clearly distinguish between HC and AD groups although the pharmacokinetics and distribution patterns in brain for two tracers were substantially different.This study revealed that although the PET amyloid imaging agents [(11)C]BF227 and [(18)F]FACT have similar chemical and biological properties, they have different pharmacokinetics, and caution must be paid for usage of the tracers.

Histamine H1-receptor (H1R) antagonists, or antihistamines, often induce sedative side effects when used for the treatment of allergic disorders. This study compared the sedative profiles of the second-generation antihistamines, fexofenadine and cetirizine, using 3 different criteria: subjective sleepiness evaluated by the Stanford Sleepiness Scale, objective psychomotor tests (simple and choice reaction time tests and visual discrimination tests at 4 different exposure durations), and measurement of histamine H1-receptor occupancy (H1RO) in the brain. Subjective sleepiness and psychomotor performance were measured in 20 healthy Japanese volunteers at baseline and 90 min after administration of fexofenadine 120 mg or cetirizine 20 mg in a double-blind, placebo-controlled crossover study. Hydroxyzine 30 mg was included as a positive control. H1RO was measured using positron emission tomography (PET) with (11)C-doxepin in 12 of the 20 subjects, and a further 11 volunteers were recruited to act as controls. In psychomotor tests, fexofenadine was not significantly different from placebo and significantly less impairing than cetirizine on some tasks, as well as significantly less impairing than hydroxyzine on all tasks. For subjective sleepiness, fexofenadine was not significantly different from placebo, whereas cetirizine showed a trend toward increased sleepiness compared with fexofenadine and placebo. H1RO was negligible with fexofenadine (-0.1%) but moderately high with cetirizine (26.0%). In conclusion, fexofenadine 120 mg is distinguishable from cetirizine 20 mg, as assessed by H1RO and psychomotor testing.

Donepezil, an acetylcholinesterase (AChE) inhibitor, has not been evaluated for its binding characteristics using a radioactive tracer, although its inhibitory action on AChE has been studied. The aim of this research is to examine whether AChE can be visualized in vivo and in vitro with [(11)C]donepezil. [5-(11)C-methoxy]Donepezil was synthesized by O-methylation using [(11)C]methyl triflate. The binding of [(11)C]donepezil to brain homogenates was higher in the brain stem and striatum, and it was lowest in the cerebellum. The in vitro autoradiographic study successfully demonstrated the specific binding of [(11)C]donepezil to AChE in the rat brain. The IC(50) value of binding was approximately 10 nM, which is comparable to the reported value for inhibiting enzyme activity (6 nM). Saturation experiments revealed that the B(max) and K(d) of [(11)C]donepezil binding in vitro are 65 fmol/mg tissue and 39.8 nM, respectively. In accordance with the in vitro bindings, the in vivo distribution of [(11)C]donepezil was heterogeneous in the rat brain. In the blocking experiments, the heterogeneous distribution disappeared in the presence of a large amount of unlabeled donepezil. These data suggest that [5-(11)C-methoxy]donepezil can be potentially useful to image AChE non-invasively in the human brain by positron emission tomography.

Histamine H₁ antagonists have hypnotic, appetite-promoting, and sedative effects. The affinities of various antidepressants for histamine receptors have only been partially determined in vitro and animal study. Positron emission tomography (PET) can clarify the in vivo dynamics of antidepressants at histamine receptors.We performed human PET imaging with [¹¹C]doxepin, a selective PET ligand of the histamine H₁ receptor (H₁R), to study the in vivo affinities of fluvoxamine and mirtazapine for the H₁R.The subjects were five male healthy Japanese volunteers. We performed cross-randomized PET imaging after single oral administration of fluvoxamine (25mg), mirtazapine (15 mg), or placebo. PET data were analyzed by region-of-interest and voxel-by-voxel analysis. We concurrently measured plasma drug concentrations, using liquid chromatography/tandem mass spectrometry and subjective sleepiness.The binding potential ratio of mirtazapine in brain cortex was significantly lower than that of fluvoxamine or placebo. Fluvoxamine did not occupy the H₁R, whereas H₁R occupancy (H₁RO) of mirtazapine reached 80-90 % in the cerebral neocortex. In the voxel-by-voxel analysis, the binding potential of mirtazapine was significantly lower than placebo in the dorsolateral prefrontal cortex, lateral temporal cortex, anterior cingulate gyrus, and posterior cingulate gyrus. The H₁RO of mirtazapine depended on the plasma drug concentration (AUC(0-180 min)) and was related to subjective sleepiness.Our results demonstrate a low affinity of fluvoxamine and a very high affinity of mirtazapine for the human brain H₁R in vivo. This study provides a basis for investigating the efficacy of new-generation antidepressants in central histamine systems.

SUMMARY We newly prepared a MAP-sensitized dog by repeated MAP treatment and studied the brain distribution of [11C]MAP in the normal and the MAP-sensitized dog using PET. The maximal level of accumulation of [11C]MAP in the sensitized dog brain was 1.4 times higher than that in the control. No difference was found in the metabolism of MAP between the two conditions. The significant increase of [11C]MAP in the MAP-sensitized brain indicates that subchronic MAP administration causes some functional change in the uptake site of MAP. The pharmacokinetic change may, in part, account for behavioral sensitization.

[11C]Methamphetamine ([11C]MAP) was synthesized by an automated on-line [11C]methylation system for positron emission tomography (PET) study. We newly produced a MAP sensitized dog by repeated MAP treatment and studied the brain distribution of [11C]MAP in the normal and the MAP sensitized dog. The maximal level of accumulation of [11C]MAP in the sensitized dog brain was 1.4 times higher than that in the control. No difference was found in the metabolism of MAP between the two conditions. The significant increase of [11C]MAP in the MAP sensitized brain indicates that subchronic MAP administration causes some functional change in uptake site of MAP.

Molecular imaging in neuroscience is a new research field that enables visualization of the impact of molecular events on brain structure and function in humans. While magnetic resonance-based imaging techniques can provide complex information at the level of system, positron emission tomography (PET) enables determination of the distribution and density of receptor and enzyme in the human brain. Previous studies using [11C]raclopride revealed that the release of neuronal dopamine was increased in human brain by psychostimulants or reward stimuli. Following on from these previous studies, we examined whether the levels of neuronal release of histamine might change [11C]doxepin binding to the H1 receptors under the influence of physiological stimuli. The purpose of the present study was to evaluate the test-retest reliability of quantitative measurement of [11C]doxepin binding between morning and afternoon and between resting and attentive waking conditions in healthy human subjects. There was a trend for a decrease in [11C]doxepin binding during attentive calculation tasks compared with that in resting conditions, but the difference (approximately 10%) was not significant. In contrast, the binding potential of [11C]doxepin in the anterior cingulate gyrus was significantly higher in the morning than that in the afternoon (approximately 19%), suggesting that higher histamine release in the morning would decrease the [11C]doxepin binding in the afternoon. This study suggests that non-invasive measurement of neuronal histamine release is feasible in humans by PET ligand-activation study, although the development of a tracer with better signal-to-noise properties is needed.

This article reviewed the bone metabolic activity around titanium implants in rat tibia under the mechanical loading condition on the implant.

There are a few findings between reduced sensory input from mastication and neurochemical denaturation of the brain. The aim of this study was to investigate the effect of different mastication on the dopaminergic system in the rat striatum using brain microdialysis (MD) and positron emission tomography (PET).

Background: Although donepezil, an acetylcholinesterase inhibitor, has been proved to be effective in ameliorating cognitive impairment in Parkinson’s disease with dementia (PDD), the responsiveness of patients to donepezil therapy varies. [5-11C-methoxy]donepezil, the radiolabeled form of donepezil, is a ligand for positron emission tomography (PET), which can be exploited for the quantitative analysis of donepezil binding to acetylcholinesterase and for cholinergic imaging. Objectives: To investigate the deficits of the cholinergic system in the brain in PDD and its association with response to donepezil therapy. Methods: Twelve patients with PDD and 13 normal control subjects underwent [5-11C-methoxy]donepezil-PET imaging. For patients with PDD, daily administration of donepezil was started after [5-11C-methoxy]donepezil-PET imaging and continued for 3 months. Results: In the PDD group, the mean total distribution volume of the cerebral cortices was 22.7% lower than that of the normal control group. The mean total distribution volume of the patients with PDD was significantly correlated with improvement of visuoperceptual function after 3 months of donepezil therapy. Conclusion: The results suggest that donepezil therapy is more effective in patients with less decrease in acetylcholinesterase, a binding site of donepezil, at least in the specific cognitive domain.