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Lopresti BJ, Stehouwer J, Reese AC, Mason NS, Royse SK, Narendran R, Laymon CM, Lopez OL, Cohen AD, Mathis CA, Villemagne VL. Kinetic modeling of the monoamine oxidase-B radioligand [ 18F]SMBT-1 in human brain with positron emission tomography. J Cereb Blood Flow Metab 2024:271678X241254679. [PMID: 38735059 DOI: 10.1177/0271678x241254679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 05/14/2024]
Abstract
This paper describes pharmacokinetic analyses of the monoamine-oxidase-B (MAO-B) radiotracer [18F](S)-(2-methylpyrid-5-yl)-6-[(3-fluoro-2-hydroxy)propoxy]quinoline ([18F]SMBT-1) for positron emission tomography (PET) brain imaging. Brain MAO-B expression is widespread, predominantly within astrocytes. Reactive astrogliosis in response to neurodegenerative disease pathology is associated with MAO-B overexpression. Fourteen elderly subjects (8 control, 5 mild cognitive impairment, 1 Alzheimer's disease) with amyloid ([11C]PiB) and tau ([18F]flortaucipir) imaging assessments underwent dynamic [18F]SMBT-1 PET imaging with arterial input function determination. [18F]SMBT-1 showed high brain uptake and a retention pattern consistent with the known MAO-B distribution. A two-tissue compartment (2TC) model where the K1/k2 ratio was fixed to a whole brain value best described [18F]SMBT-1 kinetics. The 2TC total volume of distribution (VT) was well identified and highly correlated (r2∼0.8) with post-mortem MAO-B indices. Cerebellar grey matter (CGM) showed the lowest mean VT of any region and is considered the optimal pseudo-reference region. Simplified analysis methods including reference tissue models, non-compartmental models, and standard uptake value ratios (SUVR) agreed with 2TC outcomes (r2 > 0.9) but with varying bias. We found the CGM-normalized 70-90 min SUVR to be highly correlated (r2 = 0.93) with the 2TC distribution volume ratio (DVR) with acceptable bias (∼10%), representing a practical alternative for [18F]SMBT-1 analyses.
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Affiliation(s)
- Brian J Lopresti
- Department of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Jeffrey Stehouwer
- Department of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Alexandria C Reese
- Department of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Neale S Mason
- Department of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Sarah K Royse
- Department of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Rajesh Narendran
- Department of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Charles M Laymon
- Department of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Dept. of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Oscar L Lopez
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Clinical and Translational Sciences Institute, University of Pittsburgh, Pittsburgh, PA, USA
| | - Ann D Cohen
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Chester A Mathis
- Department of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Victor L Villemagne
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
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2
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Emvalomenos GM, Kang JWM, Jupp B, Mychasiuk R, Keay KA, Henderson LA. Recent developments and challenges in positron emission tomography imaging of gliosis in chronic neuropathic pain. Pain 2024:00006396-990000000-00597. [PMID: 38713812 DOI: 10.1097/j.pain.0000000000003247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 03/05/2024] [Indexed: 05/09/2024]
Abstract
ABSTRACT Understanding the mechanisms that underpin the transition from acute to chronic pain is critical for the development of more effective and targeted treatments. There is growing interest in the contribution of glial cells to this process, with cross-sectional preclinical studies demonstrating specific changes in these cell types capturing targeted timepoints from the acute phase and the chronic phase. In vivo longitudinal assessment of the development and evolution of these changes in experimental animals and humans has presented a significant challenge. Recent technological advances in preclinical and clinical positron emission tomography, including the development of specific radiotracers for gliosis, offer great promise for the field. These advances now permit tracking of glial changes over time and provide the ability to relate these changes to pain-relevant symptomology, comorbid psychiatric conditions, and treatment outcomes at both a group and an individual level. In this article, we summarize evidence for gliosis in the transition from acute to chronic pain and provide an overview of the specific radiotracers available to measure this process, highlighting their potential, particularly when combined with ex vivo/in vitro techniques, to understand the pathophysiology of chronic neuropathic pain. These complementary investigations can be used to bridge the existing gap in the field concerning the contribution of gliosis to neuropathic pain and identify potential targets for interventions.
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Affiliation(s)
- Gaelle M Emvalomenos
- School of Medical Sciences [Neuroscience], and the Brain and Mind Centre, The University of Sydney, Sydney, Australia
| | - James W M Kang
- School of Medical Sciences [Neuroscience], and the Brain and Mind Centre, The University of Sydney, Sydney, Australia
| | - Bianca Jupp
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Australia
| | - Richelle Mychasiuk
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Australia
| | - Kevin A Keay
- School of Medical Sciences [Neuroscience], and the Brain and Mind Centre, The University of Sydney, Sydney, Australia
| | - Luke A Henderson
- School of Medical Sciences [Neuroscience], and the Brain and Mind Centre, The University of Sydney, Sydney, Australia
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3
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Fontana IC, Kumar A, Okamura N, Nordberg A. Multitracer Approach to Understanding the Complexity of Reactive Astrogliosis in Alzheimer's Brains. ACS Chem Neurosci 2024; 15:328-336. [PMID: 38133820 PMCID: PMC10797624 DOI: 10.1021/acschemneuro.3c00646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 11/28/2023] [Accepted: 12/04/2023] [Indexed: 12/23/2023] Open
Abstract
A monoamine oxidase B (MAO-B) selective positron emission tomography (PET) tracer [11C]-deuterium-l-deprenyl holds promise for imaging reactive astrogliosis in neurodegenerative diseases, such as Alzheimer's disease (AD). Two novel PET tracers ([11C]-BU99008 and [18F]-SMBT-1) have recently been developed to assess the complexity of reactive astrogliosis in the AD continuum. We have investigated the binding properties of SMBT-1, l-deprenyl, and BU99008 in AD and cognitively normal control (CN) brains. Competition binding assays with [3H]-l-deprenyl and [3H]-BU99008 versus unlabeled SMBT-1 in postmortem AD and CN temporal and frontal cortex brains demonstrated that SMBT-1 interacted with [3H]-deprenyl at a single binding site (nM range) and with [3H]-BU99008 at multiple binding sites (from nM to μM). Autoradiography studies on large frozen postmortem AD and CN hemisphere brain sections demonstrated that 1 μM SMBT-1 almost completely displaced the [3H]-l-deprenyl binding (>90%), while SMBT-1 only partly displaced the [3H]-BU99008 binding (50-60% displacement) in cortical regions. In conclusion, SMBT-1, l-deprenyl, and BU99008 interact at the same MAO-B binding site, while BU99008 shows an additional independent binding site in AD and CN brains. The high translational power of our studies in human AD and CN brains suggests that the multitracer approach with SMBT-1, l-deprenyl, and BU99008 could be useful for imaging reactive astrogliosis.
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Affiliation(s)
- Igor C. Fontana
- Division
of Clinical Geriatrics, Center for Alzheimer Research, Department
of Neurobiology, Care Sciences and Society, Karolinska Institutet, S-141 83 Stockholm, Sweden
| | - Amit Kumar
- Division
of Clinical Geriatrics, Center for Alzheimer Research, Department
of Neurobiology, Care Sciences and Society, Karolinska Institutet, S-141 83 Stockholm, Sweden
| | - Nobuyuki Okamura
- Department
of Pharmacology, Tohoku Medical and Pharmaceutical
University, Sendai 983-8536, Japan
| | - Agneta Nordberg
- Division
of Clinical Geriatrics, Center for Alzheimer Research, Department
of Neurobiology, Care Sciences and Society, Karolinska Institutet, S-141 83 Stockholm, Sweden
- Theme
Inflammation and Aging, Karolinska University
Hospital, S-141 57 Stockholm, Sweden
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4
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Harada R, Lerdsirisuk P, Shimizu Y, Yokoyama Y, Du Y, Kudo K, Ezura M, Ishikawa Y, Iwata R, Shidahara M, Ishiki A, Kikuchi A, Hatano Y, Ishihara T, Onodera O, Iwasaki Y, Yoshida M, Taki Y, Arai H, Kudo Y, Yanai K, Furumoto S, Okamura N. Preclinical Characterization of the Tau PET Tracer [ 18F]SNFT-1: Comparison of Tau PET Tracers. J Nucl Med 2023; 64:1495-1501. [PMID: 37321821 DOI: 10.2967/jnumed.123.265593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 05/03/2023] [Indexed: 06/17/2023] Open
Abstract
Tau PET tracers are expected to be sufficiently sensitive to track the progression of age-related tau pathology in the medial temporal cortex. The tau PET tracer N-(4-[18F]fluoro-5-methylpyridin-2-yl)-7-aminoimidazo[1,2-a]pyridine ([18F]SNFT-1) has been successfully developed by optimizing imidazo[1,2-a]pyridine derivatives. We characterized the binding properties of [18F]SNFT-1 using a head-to-head comparison with other reported 18F-labeled tau tracers. Methods: The binding affinity of SNFT-1 to tau, amyloid, and monoamine oxidase A and B was compared with that of the second-generation tau tracers MK-6240, PM-PBB3, PI-2620, RO6958948, JNJ-64326067, and flortaucipir. In vitro binding properties of 18F-labeled tau tracers were evaluated through the autoradiography of frozen human brain tissues from patients with diverse neurodegenerative disease spectra. Pharmacokinetics, metabolism, and radiation dosimetry were assessed in normal mice after intravenous administration of [18F]SNFT-1. Results: In vitro binding assays demonstrated that [18F]SNFT-1 possesses high selectivity and high affinity for tau aggregates in Alzheimer disease (AD) brains. Autoradiographic analysis of tau deposits in medial temporal brain sections from patients with AD showed a higher signal-to-background ratio for [18F]SNFT-1 than for the other tau PET tracers and no significant binding with non-AD tau, α-synuclein, transactiviation response DNA-binding protein-43, and transmembrane protein 106B aggregates in human brain sections. Furthermore, [18F]SNFT-1 did not bind significantly to various receptors, ion channels, or transporters. [18F]SNFT-1 showed a high initial brain uptake and rapid washout from the brains of normal mice without radiolabeled metabolites. Conclusion: These preclinical data suggest that [18F]SNFT-1 is a promising and selective tau radiotracer candidate that allows the quantitative monitoring of age-related accumulation of tau aggregates in the human brain.
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Affiliation(s)
- Ryuichi Harada
- Department of Pharmacology, Tohoku University Graduate School of Medicine, Sendai, Japan;
- Division of Brain Science, Department of Aging Research and Geriatric Medicine, Institute of Development, Aging, and Cancer, Tohoku University, Sendai, Japan
| | | | - Yuki Shimizu
- Cyclotron and Radioisotope Center, Tohoku University, Sendai, Japan
| | - Yuka Yokoyama
- Cyclotron and Radioisotope Center, Tohoku University, Sendai, Japan
| | - Yiqing Du
- Department of Pharmacology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Kaede Kudo
- Division of Brain Science, Department of Aging Research and Geriatric Medicine, Institute of Development, Aging, and Cancer, Tohoku University, Sendai, Japan
| | - Michinori Ezura
- Department of Neurology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Yoichi Ishikawa
- Cyclotron and Radioisotope Center, Tohoku University, Sendai, Japan
| | - Ren Iwata
- Cyclotron and Radioisotope Center, Tohoku University, Sendai, Japan
| | - Miho Shidahara
- Department of Quantum Science and Energy Engineering, Tohoku University, Sendai, Japan
| | - Aiko Ishiki
- Division of Brain Science, Department of Aging Research and Geriatric Medicine, Institute of Development, Aging, and Cancer, Tohoku University, Sendai, Japan
- Division of Community Medicine, Tohoku Medical and Pharmaceutical University, Sendai, Japan
| | - Akio Kikuchi
- Department of Neurology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Yuya Hatano
- Department of Neurology, Brain Research Institute, Niigata University, Niigata, Japan
| | - Tomohiko Ishihara
- Department of Neurology, Brain Research Institute, Niigata University, Niigata, Japan
| | - Osamu Onodera
- Department of Neurology, Brain Research Institute, Niigata University, Niigata, Japan
| | - Yasushi Iwasaki
- Department of Neuropathology, Institute for Medical Science of Aging, Aichi Medical University, Nagakute, Japan; and
| | - Mari Yoshida
- Department of Neuropathology, Institute for Medical Science of Aging, Aichi Medical University, Nagakute, Japan; and
| | - Yasuyuki Taki
- Division of Brain Science, Department of Aging Research and Geriatric Medicine, Institute of Development, Aging, and Cancer, Tohoku University, Sendai, Japan
| | - Hiroyuki Arai
- Division of Brain Science, Department of Aging Research and Geriatric Medicine, Institute of Development, Aging, and Cancer, Tohoku University, Sendai, Japan
| | - Yukitsuka Kudo
- Division of Brain Science, Department of Aging Research and Geriatric Medicine, Institute of Development, Aging, and Cancer, Tohoku University, Sendai, Japan
| | - Kazuhiko Yanai
- Cyclotron and Radioisotope Center, Tohoku University, Sendai, Japan
| | - Shozo Furumoto
- Cyclotron and Radioisotope Center, Tohoku University, Sendai, Japan
| | - Nobuyuki Okamura
- Division of Brain Science, Department of Aging Research and Geriatric Medicine, Institute of Development, Aging, and Cancer, Tohoku University, Sendai, Japan
- Division of Pharmacology, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, Sendai, Japan
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Fontana IC, Scarpa M, Malarte ML, Rocha FM, Ausellé-Bosch S, Bluma M, Bucci M, Chiotis K, Kumar A, Nordberg A. Astrocyte Signature in Alzheimer's Disease Continuum through a Multi-PET Tracer Imaging Perspective. Cells 2023; 12:1469. [PMID: 37296589 PMCID: PMC10253101 DOI: 10.3390/cells12111469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 05/02/2023] [Accepted: 05/19/2023] [Indexed: 06/12/2023] Open
Abstract
Reactive astrogliosis is an early event in the continuum of Alzheimer's disease (AD). Current advances in positron emission tomography (PET) imaging provide ways of assessing reactive astrogliosis in the living brain. In this review, we revisit clinical PET imaging and in vitro findings using the multi-tracer approach, and point out that reactive astrogliosis precedes the deposition of Aβ plaques, tau pathology, and neurodegeneration in AD. Furthermore, considering the current view of reactive astrogliosis heterogeneity-more than one subtype of astrocyte involved-in AD, we discuss how astrocytic body fluid biomarkers might fit into trajectories different from that of astrocytic PET imaging. Future research focusing on the development of innovative astrocytic PET radiotracers and fluid biomarkers may provide further insights into the heterogeneity of reactive astrogliosis and improve the detection of AD in its early stages.
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Affiliation(s)
- Igor C. Fontana
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm, Sweden
| | - Miriam Scarpa
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm, Sweden
| | - Mona-Lisa Malarte
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm, Sweden
| | - Filipa M. Rocha
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm, Sweden
- Instituto de Ciência Biomédicas Abel Salazar da Universidade do Porto, 4050-313 Porto, Portugal
- Faculdade de Engenharia, Universidade do Porto, 4200-465 Porto, Portugal
| | - Sira Ausellé-Bosch
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm, Sweden
- Faculty of Health and Life Sciences, Pompeu Fabra University, 08003 Barcelona, Spain
| | - Marina Bluma
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm, Sweden
| | - Marco Bucci
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm, Sweden
| | - Konstantinos Chiotis
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm, Sweden
| | - Amit Kumar
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm, Sweden
| | - Agneta Nordberg
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm, Sweden
- Theme Inflammation and Aging, Karolinska University Hospital, 141 57 Stockholm, Sweden
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6
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Fujinaga M, Ohkubo T, Yamasaki T, Kumata K, Nengaki N, Zhang MR. Scandium Triflate-Catalyzed N-[ 18F]Fluoroalkylation of Aryl- Or Heteroaryl-Amines with [ 18F]Epifluorohydrin under Mild Conditions. Org Lett 2022; 24:4024-4028. [PMID: 35613453 DOI: 10.1021/acs.orglett.2c01459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The scandium triflate-catalyzed N-[18F]fluoroalkylation of aryl- or heteroaryl-amines with [18F]epifluorohydrin ([18F]2) was investigated. This reaction is mild and provides one-step access to N-[18F]fluoroalkylated aryl- or heteroaryl-amines, which are used for positron emission tomography imaging. The use of 2,2,2-trifluoroethanol as a cosolvent improved the reaction efficiency. The use of (S)- and (R)-[18F]2 produced the corresponding enantiomeric N-[18F]fluoroalkylated anilines.
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Affiliation(s)
- Masayuki Fujinaga
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, Chiba 263-8555, Japan
| | - Takayuki Ohkubo
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, Chiba 263-8555, Japan.,SHI Accelerator Service Ltd., 1-17-6 Osaki, Shinagawa-ku, Tokyo 141-0032, Japan
| | - Tomoteru Yamasaki
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, Chiba 263-8555, Japan
| | - Katsushi Kumata
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, Chiba 263-8555, Japan
| | - Nobuki Nengaki
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, Chiba 263-8555, Japan.,SHI Accelerator Service Ltd., 1-17-6 Osaki, Shinagawa-ku, Tokyo 141-0032, Japan
| | - Ming-Rong Zhang
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, Chiba 263-8555, Japan
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7
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Harada R. [Imaging of neuropathology by PET tracers]. Nihon Yakurigaku Zasshi 2022; 157:453-457. [PMID: 36328560 DOI: 10.1254/fpj.22061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Alzheimer's disease (AD) is one of the most common causes of dementia in the world. Neurodegeneration, gliosis, and misfolded proteins such as amyloid plaques and tau tangles are neuropathological hallmarks in AD. In vivo imaging of these neuropathological lesions would be good biomarkers to understand pathophysiology as well as surrogate markers for clinical trials. We developed THK tau radiotracers including [18F]THK-5351 and tested them in humans. Validations studies identified monoamine oxidase-B (MAO-B) as the off-target binding substrate of [18F]THK-5351. Since the elevation of MAO-B, which is highly expressed in reactive astrocytes, were observed in various neurological conditions, MAO-B would be a promising target for imaging reactive astrogliosis. In fact, [18F]THK-5351 PET studies demonstrated that high tracer uptake in site susceptible regions to occur astrogliosis in various neurological disorders. However, the lack of binding selectivity affects the interpretation of PET images. Therefore, we performed lead optimization from [18F]THK-5351 generating a selective and reversible MAO-B PET tracer, [18F]SMBT-1. These translational and reverse translational studies, from the development of PET tracers to validation of PET images, led to the generation of new biomarkers. In this review, we will introduce the development of [18F]THK-5351, identification of off-target binding substrates, imaging-autopsy validations, new tracer development ([18F]SMBT-1), and finally recent clinical studies of [18F]SMBT-1.
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Affiliation(s)
- Ryuichi Harada
- Department of Pharmacology, Tohoku University Graduate School of Medicine
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