1
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Kaur T, Brooks AF, Lapsys A, Desmond TJ, Stauff J, Arteaga J, Winton WP, Scott PJH. Synthesis and Evaluation of a Fluorine-18 Radioligand for Imaging Huntingtin Aggregates by Positron Emission Tomographic Imaging. Front Neurosci 2021; 15:766176. [PMID: 34924935 PMCID: PMC8675899 DOI: 10.3389/fnins.2021.766176] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Accepted: 11/01/2021] [Indexed: 11/13/2022] Open
Abstract
Mutations in the huntingtin gene (HTT) triggers aggregation of huntingtin protein (mHTT), which is the hallmark pathology of neurodegenerative Huntington’s disease (HD). Development of a high affinity 18F radiotracer would enable the study of Huntington’s disease pathology using a non-invasive imaging modality, positron emission tomography (PET) imaging. Herein, we report the first synthesis of fluorine-18 imaging agent, 6-(5-((5-(2,2-difluoro-2-(fluoro-18F)ethoxy)pyridin-2-yl)methoxy)benzo[d]oxazol-2-yl)-2-methylpyridazin-3(2H)-one ([18F]1), a radioligand for HD and its preclinical evaluation in vitro (autoradiography of post-mortem HD brains) and in vivo (rodent and non-human primate brain PET). [18F]1 was synthesized in a 4.1% RCY (decay corrected) and in an average molar activity of 16.5 ± 12.5 GBq/μmol (445 ± 339 Ci/mmol). [18F]1 penetrated the blood-brain barrier of both rodents and primates, and specific saturable binding in post-mortem brain slices was observed that correlated to mHTT aggregates identified by immunohistochemistry.
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Affiliation(s)
- Tanpreet Kaur
- Division of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Allen F Brooks
- Division of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Alex Lapsys
- Division of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Timothy J Desmond
- Division of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Jenelle Stauff
- Division of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Janna Arteaga
- Division of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Wade P Winton
- Division of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Peter J H Scott
- Division of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, MI, United States
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2
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Drake LR, Pham JM, Desmond TJ, Mossine AV, Lee SJ, Kilbourn MR, Koeppe RA, Brooks AF, Scott PJ. Identification of AV-1451 as a Weak, Nonselective Inhibitor of Monoamine Oxidase. ACS Chem Neurosci 2019; 10:3839-3846. [PMID: 31339297 DOI: 10.1021/acschemneuro.9b00326] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
[18F]AV-1451 is one of the most widely used radiotracers for positron emission tomography (PET) imaging of tau protein aggregates in neurodegenerative disorders. While the radiotracer binds with high affinity to tau neurofibrillary tangles, extensive clinical studies have simultaneously revealed off-target tracer accumulation in areas of low tau burden such as the basal ganglia and choroid plexus. Though there are a number of possible reasons for this accumulation, it is often attributed to off-target binding to monoamine oxidase (MAO). In this paper, we investigate the association between [18F]AV-1451 and MAO through (i) enzyme inhibition assays, (ii) autoradiography with postmortem tissue samples, and (iii) nonhuman primate PET imaging. We confirm that [18F]AV-1451 is a weak inhibitor of MAO-A and -B and that MAO inhibitors can alter binding of [18F]AV-1451 in autoradiography and in vivo PET imaging.
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Affiliation(s)
- Lindsey R. Drake
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Jonathan M. Pham
- Department of Radiology, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Timothy J. Desmond
- Department of Radiology, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Andrew V. Mossine
- Department of Radiology, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - So Jeong Lee
- Department of Radiology, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Michael R. Kilbourn
- Department of Radiology, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Robert A. Koeppe
- Department of Radiology, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Allen F. Brooks
- Department of Radiology, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Peter J.H. Scott
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department of Radiology, University of Michigan, Ann Arbor, Michigan 48109, United States
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3
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Forrest TJ, Desmond TJ, Issa M, Scott PJH, Basura GJ. Evaluating Cholinergic Receptor Expression in Guinea Pig Primary Auditory and Rostral Belt Cortices After Noise Damage Using [ 3H]Scopolamine and [ 18F]Flubatine Autoradiography. Mol Imaging 2019; 18:1536012119848927. [PMID: 31099304 PMCID: PMC6537085 DOI: 10.1177/1536012119848927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Noise-induced hearing loss leads to anatomic and physiologic changes in primary auditory
cortex (A1) and the adjacent dorsal rostral belt (RB). Since acetylcholine is known to
modulate plasticity in other cortical areas, changes in A1 and RB following noise damage
may be due to changes in cholinergic receptor expression. We used
[3H]scopolamine and [18F]flubatine binding to measure muscarinic
acetylcholine receptor (mAChR) and nicotinic acetylcholine receptor (nAChR) expression,
respectively, in guinea pig A1 and RB 3 weeks following unilateral, left ear noise
exposure, and a temporary threshold shift in hearing. [3H]Scopolamine binding
decreased in right A1 and RB (contralateral to noise) compared to sham controls across all
cortical layers. [18F]Flubatine binding showed a nonsignificant upward trend in
right A1 following noise but only significantly increased in right RB and 2 layers of left
RB (ipsilateral to noise). This selective response may ultimately influence cortical
plasticity and function. The mechanism(s) by which cholinergic receptors are altered
following noise exposure remain unknown. However, these data demonstrate noise exposure
may differentially influence mAChRs that typically populate interneurons in A1 and RB more
than nAChRs that are traditionally located on thalamocortical projections and provide
motivation for cholinergic imaging in clinical patient populations of temporary or
permanent hearing loss.
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Affiliation(s)
- Taylor J Forrest
- 1 Department of Otolaryngology-Head and Neck Surgery, Kresge Hearing Research Institute University of Michigan, Ann Arbor, MI, USA.,2 Kresge Hearing Research Institute University of Michigan, Ann Arbor, MI, USA.,3 Division of Nuclear Medicine, Department of Radiology, University of Michigan, Ann Arbor MI, USA
| | - Timothy J Desmond
- 3 Division of Nuclear Medicine, Department of Radiology, University of Michigan, Ann Arbor MI, USA
| | - Mohamad Issa
- 1 Department of Otolaryngology-Head and Neck Surgery, Kresge Hearing Research Institute University of Michigan, Ann Arbor, MI, USA.,2 Kresge Hearing Research Institute University of Michigan, Ann Arbor, MI, USA
| | - Peter J H Scott
- 3 Division of Nuclear Medicine, Department of Radiology, University of Michigan, Ann Arbor MI, USA
| | - Gregory J Basura
- 1 Department of Otolaryngology-Head and Neck Surgery, Kresge Hearing Research Institute University of Michigan, Ann Arbor, MI, USA.,2 Kresge Hearing Research Institute University of Michigan, Ann Arbor, MI, USA
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4
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Stewart MN, Shao X, Desmond TJ, Forrest TJ, Arteaga J, Stauff J, Scott PJH. Synthesis and pre-clinical evaluation of a potential radiotracer for PET imaging of the dopamine D 3 receptor. Medchemcomm 2018; 9:1315-1322. [PMID: 30151086 PMCID: PMC6097203 DOI: 10.1039/c8md00094h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Accepted: 06/28/2018] [Indexed: 01/11/2023]
Abstract
There is considerable interest in using positron emission tomography (PET) imaging to understand the function of dopamine D3 receptors. Due to high sequence homology with D2 receptors, development of D3-selective PET radiotracers has been challenging. In an effort to overcome this issue, we report the radiosynthesis of a new selective D3 ligand with carbon-11 ([11C]1 ), and its initial preclincial evaluation as a potential PET radiotracer for in vivo imaging of D3 receptors. [11C]1 was prepared via [11C]CO2 fixation in 0.1% non-corrected radiochemical yield, good radiochemical purity (>95%) and high specific activity (>2000 Ci mmol-1). [11C]1 exhibited specific binding to D3 receptors using ex vivo autoradiography experiments with rat brain, but only 14-fold selectivity over D2 receptors which is lower than the 1400-fold value reported previously for cell studies. Rodent PET imaging revealed reasonable uptake of the radiotracer in areas of the brain known to be rich in D3 receptors.
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Affiliation(s)
- Megan N Stewart
- Department of Radiology , University of Michigan Medical School , Ann Arbor , MI 48109 , USA .
- Department of Medicinal Chemistry , University of Michigan , Ann Arbor , MI 48105 , USA
| | - Xia Shao
- Department of Radiology , University of Michigan Medical School , Ann Arbor , MI 48109 , USA .
| | - Timothy J Desmond
- Department of Radiology , University of Michigan Medical School , Ann Arbor , MI 48109 , USA .
| | - Taylor J Forrest
- Department of Radiology , University of Michigan Medical School , Ann Arbor , MI 48109 , USA .
| | - Janna Arteaga
- Department of Radiology , University of Michigan Medical School , Ann Arbor , MI 48109 , USA .
| | - Jenelle Stauff
- Department of Radiology , University of Michigan Medical School , Ann Arbor , MI 48109 , USA .
| | - Peter J H Scott
- Department of Radiology , University of Michigan Medical School , Ann Arbor , MI 48109 , USA .
- Department of Medicinal Chemistry , University of Michigan , Ann Arbor , MI 48105 , USA
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5
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Thompson S, Rodnick ME, Stauff J, Arteaga J, Desmond TJ, Scott PJH, Viglianti BL. Automated synthesis of [ 68Ga]oxine, improved preparation of 68Ga-labeled erythrocytes for blood-pool imaging, and preclinical evaluation in rodents. Medchemcomm 2018; 9:454-459. [PMID: 30108935 PMCID: PMC6071839 DOI: 10.1039/c7md00607a] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 01/31/2018] [Indexed: 01/05/2023]
Abstract
Radiolabeled erythrocytes have multiple applications in nuclear medicine, including blood pool imaging. Historically they have been labeled with SPECT radionuclides. A PET blood pool imaging agent is highly desirable as it would improve clinical applications with better image quality and resolution, higher sensitivity, and dynamic scanning capabilities. With the coming of age of modern 68Ge/68Ga generator systems, gallium-68 is now widely accessible. In this paper we describe an updated method for the preparation of 68Ga-labeled erythrocytes and their preliminary use in rodent blood pool imaging. A novel automated synthesis of [68Ga]oxine using a 68Ga/68Ge generator and automated synthesis module is reported. [68Ga]Oxine was synthesized in 50 ± 5% (n = 3) non-decay corrected radiochemical yield and >99% radiochemical purity. Rat and human erythrocytes were successfully labeled with the complex in 42% RCY, and the 68Ga-labeled erythrocytes have been shown to clearly image the blood pool in a healthy rat. Human erythrocytes labelled with [68Ga]oxine were shown to be viable up to 2 hours post-labelling, and washout of the radiolabel was minimal up to 1 hour post-labelling. Further optimization of the labeling method to translate for use in human cardiac and oncologic blood pool PET imaging studies, is underway.
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Affiliation(s)
- Stephen Thompson
- Department of Radiology , University of Michigan Medical School , Ann Arbor , MI 48109 , USA . ; Tel: (+1) 919 451 0813
| | - Melissa E Rodnick
- Department of Radiology , University of Michigan Medical School , Ann Arbor , MI 48109 , USA . ; Tel: (+1) 919 451 0813
| | - Jenelle Stauff
- Department of Radiology , University of Michigan Medical School , Ann Arbor , MI 48109 , USA . ; Tel: (+1) 919 451 0813
| | - Janna Arteaga
- Department of Radiology , University of Michigan Medical School , Ann Arbor , MI 48109 , USA . ; Tel: (+1) 919 451 0813
| | - Timothy J Desmond
- Department of Radiology , University of Michigan Medical School , Ann Arbor , MI 48109 , USA . ; Tel: (+1) 919 451 0813
| | - Peter J H Scott
- Department of Radiology , University of Michigan Medical School , Ann Arbor , MI 48109 , USA . ; Tel: (+1) 919 451 0813
| | - Benjamin L Viglianti
- Department of Radiology , University of Michigan Medical School , Ann Arbor , MI 48109 , USA . ; Tel: (+1) 919 451 0813
- Department of Veterans Administration , Ann Arbor , MI 48105 , USA
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6
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Scott PJH, Shao X, Desmond TJ, Hockley BG, Sherman P, Quesada CA, Frey KA, Koeppe RA, Kilbourn MR, Bohnen NI. Investigation of Proposed Activity of Clarithromycin at GABAA Receptors Using [(11)C]Flumazenil PET. ACS Med Chem Lett 2016; 7:746-50. [PMID: 27563397 DOI: 10.1021/acsmedchemlett.5b00435] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 06/01/2016] [Indexed: 11/28/2022] Open
Abstract
Clarithromycin is a potential treatment for hypersomnia acting through proposed negative allosteric modulation of GABAA receptors. We were interested whether this therapeutic benefit might extend to Parkinson's disease (PD) patients because GABAergic neurotransmission is implicated in postural control. Prior to initiating clinical studies in PD patients, we wished to better understand clarithromycin's mechanism of action. In this work we investigated whether the proposed activity of clarithromycin at the GABAA receptor is associated with the benzodiazepine binding site using in vivo [(11)C]flumazenil positron emission tomography (PET) in primates and ex vivo [(3)H]flumazenil autoradiography in rat brain. While the studies demonstrate that clarithromycin does not change the K d of FMZ, nor does it competitively displace FMZ, there is preliminary evidence from the primate PET imaging studies that clarithromycin delays dissociation and washout of flumazenil from the primate brain in a dose-dependent fashion. These findings would be consistent with the proposed GABAA allosteric modulator function of clarithromycin. While the results are only preliminary, further investigation of the interaction of clarithromycin with GABA receptors and/or GABAergic medications is warranted, and therapeutic applications of clarithromycin alone or in combination with flumazenil, to treat hyper-GABAergic status in PD at minimally effective doses, should also be pursued.
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Affiliation(s)
- Peter J. H. Scott
- Division of Nuclear Medicine, Department of Radiology, The University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
- The Interdepartmental Program in Medicinal Chemistry, The University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Xia Shao
- Division of Nuclear Medicine, Department of Radiology, The University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Timothy J. Desmond
- Division of Nuclear Medicine, Department of Radiology, The University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Brian G. Hockley
- Division of Nuclear Medicine, Department of Radiology, The University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Phillip Sherman
- Division of Nuclear Medicine, Department of Radiology, The University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Carole A. Quesada
- Division of Nuclear Medicine, Department of Radiology, The University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Kirk A. Frey
- Division of Nuclear Medicine, Department of Radiology, The University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
- Department
of Neurology, The University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Robert A. Koeppe
- Division of Nuclear Medicine, Department of Radiology, The University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Michael R. Kilbourn
- Division of Nuclear Medicine, Department of Radiology, The University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Nicolaas I. Bohnen
- Division of Nuclear Medicine, Department of Radiology, The University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
- Department
of Neurology, The University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
- Neurology Service and Geriatrics Research,
Education, and Clinical Center, Veterans Affairs Ann Arbor Healthcare System, Ann Arbor, Michigan United States
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7
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Cary BP, Brooks AF, Fawaz MV, Drake LR, Desmond TJ, Sherman P, Quesada CA, Scott PJH. Synthesis and Evaluation of [(18)F]RAGER: A First Generation Small-Molecule PET Radioligand Targeting the Receptor for Advanced Glycation Endproducts. ACS Chem Neurosci 2016; 7:391-8. [PMID: 26771209 DOI: 10.1021/acschemneuro.5b00319] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The receptor for advanced glycation endproducts (RAGE) is a 35 kDa transmembrane receptor that belongs to the immunoglobulin superfamily of cell surface molecules. Its role in Alzheimer's disease (AD) is complex, but it is thought to mediate influx of circulating amyloid-β into the brain as well as amplify Aβ-induced pathogenic responses. RAGE is therefore of considerable interest as both a diagnostic and a therapeutic target in AD. Herein we report the synthesis and preliminary preclinical evaluation of [(18)F]RAGER, the first small molecule PET radiotracer for RAGE (Kd = 15 nM). Docking studies proposed a likely binding interaction between RAGE and RAGER, [(18)F]RAGER autoradiography showed colocalization with RAGE identified by immunohistochemistry in AD brain samples, and [(18)F]RAGER microPET confirmed CNS penetration and increased uptake in areas of the brain known to express RAGE. This first generation radiotracer represents initial proof-of-concept and a promising first step toward quantifying CNS RAGE activity using PET. However, there were high levels of nonspecific [(18)F]RAGER binding in vitro, likely due to its high log P (experimental log P = 3.5), and rapid metabolism of [(18)F]RAGER in rat liver microsome studies. Therefore, development of second generation ligands with improved imaging properties would be advantageous prior to anticipated translation into clinical PET imaging studies.
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Affiliation(s)
- Brian P. Cary
- Division
of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Allen F. Brooks
- Division
of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Maria V. Fawaz
- Division
of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
- The
Interdepartmental Program in Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Lindsey R. Drake
- The
Interdepartmental Program in Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Timothy J. Desmond
- Division
of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Phillip Sherman
- Division
of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Carole A. Quesada
- Division
of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Peter J. H. Scott
- Division
of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
- The
Interdepartmental Program in Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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8
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Cary BP, Brooks AF, Fawaz MV, Shao X, Desmond TJ, Carpenter GM, Sherman P, Quesada CA, Albin RL, Scott PJH. Targeting Metal-Aβ Aggregates with Bifunctional Radioligand [ 11C]L2-b and a Fluorine-18 Analogue [ 18F]FL2-b. ACS Med Chem Lett 2015; 6:112-116. [PMID: 25705326 PMCID: PMC4329991 DOI: 10.1021/ml500413d] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 11/09/2014] [Indexed: 11/29/2022] Open
Abstract
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Interest
in quantifying metal-Aβ species in vivo led
to the synthesis and evaluation of [11C]L2-b and [18F]FL2-b as radiopharmaceuticals for studying the metallobiology
of Alzheimer’s disease (AD) using positron emission tomography
(PET) imaging. [11C]L2-b was synthesized in 3.6% radiochemical
yield (nondecay corrected, n = 3), >95% radiochemical
purity, from the corresponding desmethyl precursor. [18F]FL2-b was synthesized in 1.0% radiochemical yield (nondecay corrected, n = 3), >99% radiochemical purity, from a 6-chloro pyridine
precursor. Autoradiography experiments with AD positive and healthy
control brain samples were used to determine the specificity of binding
for the radioligands compared to [11C]PiB, a known imaging
agent for β-amyloid (Aβ) aggregates. The Kd for [11C]L2-b and [18F]FL2-b were
found to be 3.5 and 9.4 nM, respectively, from those tissue studies.
Displacement studies of [11C]L2-b and [18F]FL2-b
with PiB and AV-45 determined that L2-b binds to Aβ aggregates
differently from known radiopharmaceuticals. Finally, brain uptake
of [11C]L2-b was examined through microPET imaging in healthy
rhesus macaque, which revealed a maximum uptake at 2.5 min (peak SUV
= 2.0) followed by rapid egress (n = 2).
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Affiliation(s)
- Brian P. Cary
- Division of Nuclear Medicine, Department of Radiology, The University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Allen F. Brooks
- Division of Nuclear Medicine, Department of Radiology, The University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Maria V. Fawaz
- Division of Nuclear Medicine, Department of Radiology, The University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Xia Shao
- Division of Nuclear Medicine, Department of Radiology, The University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Timothy J. Desmond
- Division of Nuclear Medicine, Department of Radiology, The University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Garrett M. Carpenter
- Division of Nuclear Medicine, Department of Radiology, The University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Phillip Sherman
- Division of Nuclear Medicine, Department of Radiology, The University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Carole A. Quesada
- Division of Nuclear Medicine, Department of Radiology, The University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Roger L. Albin
- Geriatrics Research, Education, and Clinical Center, Veterans Affairs Ann Arbor Healthcare System, Ann Arbor, Michigan 48105, United States
- Department
of Neurology, The University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
- Michigan Alzheimer Disease Center, The University of Michigan, Ann Arbor, Michigan 48105, United States
| | - Peter J. H. Scott
- Division of Nuclear Medicine, Department of Radiology, The University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
- The Interdepartmental
Program in Medicinal Chemistry, The University of Michigan, Ann Arbor, Michigan 48109, United States
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9
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Fawaz M, Brooks AF, Rodnick ME, Carpenter GM, Shao X, Desmond TJ, Sherman P, Quesada CA, Hockley BG, Kilbourn MR, Albin RL, Frey KA, Scott PJH. High affinity radiopharmaceuticals based upon lansoprazole for PET imaging of aggregated tau in Alzheimer's disease and progressive supranuclear palsy: synthesis, preclinical evaluation, and lead selection. ACS Chem Neurosci 2014; 5:718-30. [PMID: 24896980 PMCID: PMC4140593 DOI: 10.1021/cn500103u] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2014] [Revised: 06/04/2014] [Indexed: 01/05/2023] Open
Abstract
Abnormally aggregated tau is the hallmark pathology of tauopathy neurodegenerative disorders and is a target for development of both diagnostic tools and therapeutic strategies across the tauopathy disease spectrum. Development of carbon-11- or fluorine-18-labeled radiotracers with appropriate affinity and specificity for tau would allow noninvasive quantification of tau burden using positron emission tomography (PET) imaging. We have synthesized [(18)F]lansoprazole, [(11)C]N-methyl lansoprazole, and [(18)F]N-methyl lansoprazole and identified them as high affinity radiotracers for tau with low to subnanomolar binding affinities. Herein, we report radiosyntheses and extensive preclinical evaluation with the aim of selecting a lead radiotracer for translation into human PET imaging trials. We demonstrate that [(18)F]N-methyl lansoprazole, on account of the favorable half-life of fluorine-18 and its rapid brain entry in nonhuman primates, favorable kinetics, low white matter binding, and selectivity for binding to tau over amyloid, is the lead compound for progression into clinical trials.
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Affiliation(s)
- Maria
V. Fawaz
- Division
of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Allen F. Brooks
- Division
of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Melissa E. Rodnick
- Division
of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Garrett M. Carpenter
- Division
of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Xia Shao
- Division
of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Timothy J. Desmond
- Division
of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Phillip Sherman
- Division
of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Carole A. Quesada
- Division
of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Brian G. Hockley
- Division
of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Michael R. Kilbourn
- Division
of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Roger L. Albin
- Geriatrics
Research, Education and Clinical Center, Veterans Affairs Ann Arbor Healthcare System, Ann Arbor, Michigan 48105, United States
- Department
of Neurology, The University of Michigan
Medical School, Ann Arbor, Michigan 48109, United States
- Michigan Alzheimer
Disease Center and The Interdepartmental Program in
Medicinal Chemistry, The University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Kirk A. Frey
- Division
of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Peter J. H. Scott
- Division
of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
- Michigan Alzheimer
Disease Center and The Interdepartmental Program in
Medicinal Chemistry, The University of Michigan, Ann Arbor, Michigan 48109, United States
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Cole EL, Shao X, Sherman P, Quesada C, Fawaz MV, Desmond TJ, Scott PJH. Synthesis and evaluation of [(11)C]PyrATP-1, a novel radiotracer for PET imaging of glycogen synthase kinase-3β (GSK-3β). Nucl Med Biol 2014; 41:507-12. [PMID: 24768148 PMCID: PMC4034144 DOI: 10.1016/j.nucmedbio.2014.03.025] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2014] [Revised: 03/23/2014] [Accepted: 03/27/2014] [Indexed: 11/24/2022]
Abstract
INTRODUCTION The dysfunction of glycogen synthase kinase-3β (GSK-3β) has been implicated in a number of diseases, including Alzheimer's disease. The ability to non-invasively quantify GSK-3β activity in vivo is therefore of critical importance, and this work is focused upon development of inhibitors of GSK-3β radiolabeled with carbon-11 to examine quantification of the enzyme using positron emission tomography (PET) imaging. METHODS (11)C PyrATP-1 was prepared from the corresponding desmethyl-piperazine precursor in an automated synthesis module. In vivo rodent and primate imaging studies were conducted on a Concorde MicroPET P4 scanner to evaluate imaging properties and in vitro autoradiography studies with rat brain samples were carried out to examine specific binding. RESULTS 2035±518MBq (55±14mCi) of [(11)C]PyrATP-1 was obtained (1%-2% non-corrected radiochemical yield at end-of-synthesis based upon [(11)C]CO2) with high chemical (>95%) and radiochemical (>99%) purities, and good specific activities (143±52GBq/μmol (3874±1424Ci/mmol)), n=5. In vivo microPET imaging studies revealed poor brain uptake in rodents and non-human primates. Pretreatment of rodents with cyclosporin A resulted in moderately increased brain uptake suggesting Pgp transporter involvement. Autoradiography demonstrated high levels of specific binding in areas of the rodent brain known to be rich in GSK-3β. CONCLUSION (11)C PyrATP-1 is readily synthesized using standard carbon-11 radiochemistry. However the poor brain uptake in rodents and non-human primates indicates that the radiotracer is not suitable for the purposes of quantifying GSK-3β in neurological and psychiatric disorders.
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Affiliation(s)
- Erin L Cole
- Division of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Xia Shao
- Division of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Phillip Sherman
- Division of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Carole Quesada
- Division of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Maria V Fawaz
- Division of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Timothy J Desmond
- Division of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Peter J H Scott
- Division of Nuclear Medicine, Department of Radiology, University of Michigan Medical School, Ann Arbor, MI, USA; The Interdepartmental Program in Medicinal Chemistry, University of Michigan, Ann Arbor, MI, USA.
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11
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Shao X, Carpenter GM, Desmond TJ, Sherman P, Quesada CA, Fawaz M, Brooks AF, Kilbourn MR, Albin RL, Frey KA, Scott PJH. Evaluation of [(11)C]N-Methyl Lansoprazole as a Radiopharmaceutical for PET Imaging of Tau Neurofibrillary Tangles. ACS Med Chem Lett 2012; 3:936-41. [PMID: 24900410 DOI: 10.1021/ml300216t] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 09/25/2012] [Indexed: 01/27/2023] Open
Abstract
[(11)C]N-Methyl lansoprazole ([(11)C]NML, 3) was synthesized and evaluated as a radiopharmaceutical for quantifying tau neurofibrillary tangle (NFT) burden using positron emission tomography (PET) imaging. [(11)C]NML was synthesized from commercially available lansoprazole in 4.6% radiochemical yield (noncorrected RCY, based upon [(11)C]MeI), 99% radiochemical purity, and 16095 Ci/mmol specific activity (n = 5). Log P was determined to be 2.18. A lack of brain uptake in rodent microPET imaging revealed [(11)C]NML to be a substrate for the rodent permeability-glycoprotein 1 (PGP) transporter, but this could be overcome by pretreating with cyclosporin A to block the PGP. Contrastingly, [(11)C]NML was not found to be a substrate for the primate PGP, and microPET imaging in rhesus revealed [(11)C]NML uptake in the healthy primate brain of ∼1600 nCi/cc maximum at 3 min followed by rapid egress to 500 nCi/cc. Comparative autoradiography between wild-type rats and transgenic rats expressing human tau (hTau +/+) revealed 12% higher uptake of [(11)C]NML in the cortex of brains expressing human tau. Further autoradiography with tau positive brain samples from progressive supranuclear palsy (PSP) patients revealed colocalization of [(11)C]NML with tau NFTs identified using modified Bielschowsky staining. Finally, saturation binding experiments with heparin-induced tau confirmed K d and Bmax values of [(11)C]NML as 700 pM and 0.214 fmol/μg, respectively.
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Affiliation(s)
- Xia Shao
- Division of Nuclear Medicine, Department of Radiology, The University of Michigan Medical School, Ann Arbor,
Michigan 48109, United States
| | - Garrett M. Carpenter
- Division of Nuclear Medicine, Department of Radiology, The University of Michigan Medical School, Ann Arbor,
Michigan 48109, United States
| | - Timothy J. Desmond
- Division of Nuclear Medicine, Department of Radiology, The University of Michigan Medical School, Ann Arbor,
Michigan 48109, United States
| | - Phillip Sherman
- Division of Nuclear Medicine, Department of Radiology, The University of Michigan Medical School, Ann Arbor,
Michigan 48109, United States
| | - Carole A. Quesada
- Division of Nuclear Medicine, Department of Radiology, The University of Michigan Medical School, Ann Arbor,
Michigan 48109, United States
| | - Maria Fawaz
- Division of Nuclear Medicine, Department of Radiology, The University of Michigan Medical School, Ann Arbor,
Michigan 48109, United States
| | - Allen F. Brooks
- Division of Nuclear Medicine, Department of Radiology, The University of Michigan Medical School, Ann Arbor,
Michigan 48109, United States
| | - Michael R. Kilbourn
- Division of Nuclear Medicine, Department of Radiology, The University of Michigan Medical School, Ann Arbor,
Michigan 48109, United States
| | - Roger L. Albin
- Geriatrics Research, Education, and Clinical Center, VAAAHS, Ann Arbor, Michigan 48105, United States
- Department of Neurology, The University of Michigan Medical School, Ann Arbor,
Michigan 48109, United States
| | - Kirk A. Frey
- Division of Nuclear Medicine, Department of Radiology, The University of Michigan Medical School, Ann Arbor,
Michigan 48109, United States
- Department of Neurology, The University of Michigan Medical School, Ann Arbor,
Michigan 48109, United States
| | - Peter J. H. Scott
- Division of Nuclear Medicine, Department of Radiology, The University of Michigan Medical School, Ann Arbor,
Michigan 48109, United States
- The Interdepartmental Program in Medicinal Chemistry, The University of Michigan, Ann Arbor, Michigan 48109,
United States
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12
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Corcoran KA, Desmond TJ, Frey KA, Maren S. Hippocampal inactivation disrupts the acquisition and contextual encoding of fear extinction. J Neurosci 2005; 25:8978-87. [PMID: 16192388 PMCID: PMC6725608 DOI: 10.1523/jneurosci.2246-05.2005] [Citation(s) in RCA: 294] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2005] [Revised: 08/15/2005] [Accepted: 08/15/2005] [Indexed: 11/21/2022] Open
Abstract
In recent studies, inactivation of the dorsal hippocampus before the retrieval of extinguished fear memories disrupted the context-dependent expression of these memories. In the present experiments, we examined the role of the dorsal hippocampus in the acquisition of extinction. After pairing an auditory conditional stimulus (CS) with an aversive footshock [unconditional stimulus (US)], rats received an extinction session in which the CS was presented without the US. In experiment 1, infusion of muscimol, a GABAA receptor agonist, into the dorsal hippocampus before the extinction training session decreased the rate of extinction. Moreover, when later tested for fear to the extinguished CS, all rats that had received hippocampal inactivation before extinction training demonstrated renewed fear regardless of the context in which testing took place. This suggests a role for the dorsal hippocampus in both acquiring the extinction memory and encoding the CS-context relationship that yields the context dependence of extinction. In experiment 2, inactivation of the dorsal hippocampus before testing also disrupted the context dependence of fear to the extinguished CS. In experiment 3, quantitative autoradiography revealed the boundaries of muscimol diffusion after infusion into the dorsal hippocampus. Together, these results reveal that the dorsal hippocampus is involved in the acquisition, contextual encoding, and context-dependent retrieval of fear extinction. Learning and remembering when and where aversive events occur is essential for adaptive emotional regulation.
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Affiliation(s)
- Kevin A Corcoran
- Department of Psychology, University of Michigan, Ann Arbor, Michigan 48109-1043, USA
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Hamstra DA, Moffat BA, Hall DE, Young JM, Desmond TJ, Carter J, Pietronigro D, Frey KA, Rehemtulla A, Ross BD. Intratumoral injection of BCNU in ethanol (DTI-015) results in enhanced delivery to tumor – a pharmacokinetic study. J Neurooncol 2005; 73:225-38. [PMID: 15980973 DOI: 10.1007/s11060-004-5675-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2004] [Accepted: 11/01/2004] [Indexed: 10/25/2022]
Abstract
Solvent facilitated perfusion (SFP) has been proposed as a technique to increase the delivery of chemotherapeutic agents to tumors. SFP entails direct injection of the agent into the tumor in a water-miscible organic solvent, and because the solvent moves easily through both aqueous solutions and cellular membranes it drives the penetration of the solubilized anticancer agent throughout the tumor. To test this hypothesis, we compared the pharmacokinetics (PK) of 14C-labeled 1,3-bis-chlorethyl-1-nitrosourea (BCNU) in intra-cerebral 9L rat gliomas after intravenous (IV) infusion in 90% saline--10% ethanol or direct intratumoral (IT) injection of 14C-BCNU in 100% ethanol (DTI-015). Treatment with DTI-015 yielded a peak radioactive count (Cmax) for the 14C label that was 100-1000 fold higher in the tumor than in all other tissues in addition to a concentration in the tumor that was 100-fold higher than that achieved following IV infusion of 14C-BCNU. Pathologic and auto-radiographic analysis of tissue sections following IT injection of 14C-BCNU in ethanol into either tumor or normal rat brain revealed both an enhanced local volume of distribution and an increased concentration of BCNU delivered to tumor compared to non-tumor bearing brain. To investigate the mechanism behind the SFP of BCNU to the tumor both dynamic contrast and perfusion MRI were performed on 9L tumors before and after treatment and demonstrated a decrease in tumor perfusion following IT injection of DTI-015. Finally, initial PK of patient blood samples following administration of DTI-015 into relapsed high-grade glioma indicated a 20-fold decrease in systemic exposure to BCNU compared to IV infusion of BCNU providing further evidence for the enhanced therapeutic ratio observed for DTI-015.
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Affiliation(s)
- Daniel A Hamstra
- The Department of Radiation, The University of Michigan Medical Center, Ann Arbor, MI 48109-0648, USA
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Kilbourn MR, Kemmerer ES, Desmond TJ, Sherman PS, Frey KA. Differential effects of scopolamine on in vivo binding of dopamine transporter and vesicular monoamine transporter radioligands in rat brain. Exp Neurol 2004; 188:387-90. [PMID: 15246838 DOI: 10.1016/j.expneurol.2004.05.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2004] [Revised: 04/27/2004] [Accepted: 05/04/2004] [Indexed: 11/25/2022]
Abstract
The in vivo equilibrium specific binding of d-threo-[3H]methylphenidate, a radioligand for the dopamine transporter (DAT), and +-alpha-[3H]dihydrotetrabenazine, a radioligand for the vesicular monoamine transporter (VMAT2), were examined in rat brain with and without prior administration of 5 mg/kg scopolamine. Drug-treated animals exhibited a 30% increase in d-threo-[3H]methylphenidate binding to the DAT in the striatum relative to controls. No changes in specific binding of +-alpha-[3H]dihydrotetrabenazine were observed in any brain region following scopolamine pretreatment. Cholinergic drugs thus differentially affect in vivo specific binding of DAT and VMAT2 radioligands, suggesting this should be a consideration in selection of in vivo markers for imaging studies of dopaminergic terminals in the brain of animals and humans.
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Affiliation(s)
- Michael R Kilbourn
- Department of Radiology, Division of Nuclear Medicine, University of Michigan Medical School, Ann Arbor 48109, USA.
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Maren S, Ferrario CR, Corcoran KA, Desmond TJ, Frey KA. Protein synthesis in the amygdala, but not the auditory thalamus, is required for consolidation of Pavlovian fear conditioning in rats. Eur J Neurosci 2003; 18:3080-8. [PMID: 14656303 DOI: 10.1111/j.1460-9568.2003.03063.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The amygdala is an essential neural substrate for Pavlovian fear conditioning. Nevertheless, long-term synaptic plasticity in amygdaloid afferents, such as the auditory thalamus, may contribute to the formation of fear memories. We therefore compared the influence of protein synthesis inhibition in the amygdala and the auditory thalamus on the consolidation of Pavlovian fear conditioning in Long-Evans rats. Rats received three tone-footshock trials in a novel conditioning chamber. Immediately after fear conditioning, rats were infused intra-cranially with the protein synthesis inhibitor, anisomycin. Conditional fear to the tone and conditioning context was assessed by measuring freezing behaviour in separate retention tests conducted at least 24 h following conditioning. Post-training infusion of anisomycin into the amygdala impaired conditional freezing to both the auditory and contextual stimuli associated with footshock. In contrast, intra-thalamic infusions of anisomycin or a broad-spectrum protein kinase inhibitor [1-(5'-isoquinolinesulphonyl)-2-methylpiperazine, H7] did not affect conditional freezing during the retention tests. Pre-training intra-thalamic infusion of the NMDA receptor antagonist 2-amino-5-phosphonopentanoic acid (APV), which blocks synaptic transmission in the auditory thalamus, produced a selective deficit in the acquisition of auditory fear conditioning. Autoradiographic assays of cerebral [14C]-leucine incorporation revealed similar levels of protein synthesis inhibition in the amygdala and thalamus following intra-cranial anisomycin infusions. These results reveal that the establishment of long-term fear memories requires protein synthesis in the amygdala, but not the thalamus, after auditory fear conditioning. Forms of synaptic plasticity that depend on protein synthesis, such as long-term potentiation, are likely candidates for the encoding and long-term storage of fear memories in the amygdala.
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Affiliation(s)
- Stephen Maren
- Department of Psychology, University of Michigan, 525 E. University Avenue, Ann Arbor, MI 48109-1109, USA.
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16
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Kemmerer ES, Desmond TJ, Albin RL, Kilbourn MR, Frey KA. Treatment effects on nigrostriatal projection integrity in partial 6-OHDA lesions: comparison of L-DOPA and pramipexole. Exp Neurol 2003; 183:81-6. [PMID: 12957491 DOI: 10.1016/s0014-4886(03)00096-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
There is controversy over potential effects of dopaminergic replacement therapies on the partially lesioned nigrostriatal dopaminergic projection. We evaluated indirect (levodopa, L-DOPA) versus direct (pramipexole, PRA) dopaminergic treatment effects on nigrostriatal lesion severity as measured with vesicular monoamine transporter type-2 (VMAT2) binding. Prior studies have shown that striatal VMAT2 density provides an objective estimate of dopaminergic neuronal integrity, without confounding effects of compensatory regulation. Partial unilateral median forebrain bundle lesions were made by injection of 6-hydroxydopamine in adult male Sprague-Dawley rats. Lesion severity was estimated using rotational behavior after injections of apomorphine and amphetamine. Rats were ranked and matched in pairs by rotation and assigned to receive either PRA (1 mg/kg/day) or L-DOPA/benserazide (100/25 mg/kg/day) ip via osmotic pump. After 4 weeks of drug treatment, in vitro autoradiography was performed with [(3)H]methoxytetrabenazine to measure striatal VMAT2 binding density. Lesion-to-intact VMAT2 density correlated with rotation in both treatment groups. There was no treatment effect on VMAT2 expression in the partially lesioned striatum and thus no differential effect of indirect versus direct dopamimetic treatment on nigrostriatal integrity.
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Affiliation(s)
- Elyse S Kemmerer
- Neuroscience Program, The University of Michigan, Ann Arbor, MI, USA
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17
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Abstract
Vesicular monoamine transporter type 2 and benzodiazepine binding site expressions were examined with quantitative autoradiography in postmortem striata from 19 patients with dementia with Lewy bodies, seven patients with dementia with Lewy bodies and Alzheimer's disease, 12 patients with Alzheimer's disease, and eight neurologically normal subjects. Striatal vesicular monoamine transporter type 2 expression in dementia with Lewy bodies and in dementia with Lewy bodies plus Alzheimer's disease was reduced significantly, indicating degeneration of nigrostriatal projections. Striatal benzodiazepine binding site expression was unchanged, indicating preserved intrinsic striatal neuropil. Vesicular monoamine transporter type 2 and benzodiazepine binding site expressions were each preserved in Alzheimer's disease striatum. We conclude that dementia with Lewy bodies may be distinguished from Alzheimer's disease by postmortem examination or by future in vivo measurements of the striatal vesicular monoamine transporter type 2.
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Affiliation(s)
- Masahiko Suzuki
- Department of Radiology (Nuclear Medicine), University of Michigan, 1500 East Medical Center Drive, Ann Arbor, MI 48109-0028, USA
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18
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Cocivera M, Desmond TJ, Ferguson G, Kaitner B, Lalor FJ, O'Sullivan DJ. Stereochemically nonrigid bis(olefin)rhodium poly(1-pyrazolyl)borato complexes. 1. Synthesis and conversion into new rhodium(I) and rhodium(III) complexes. The crystal and molecular structure of [tetrakis(1-pyrazolyl)borato]diiodocarbonylrhodium(III) methylene chloride solvate. Organometallics 2002. [DOI: 10.1021/om00069a004] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Abstract
OBJECTIVE To determine the status of cholinergic and monoaminergic vesicular transporter binding sites in progressive supranuclear palsy (PSP). METHODS The authors determined autoradiographically the regional expression of acetylcholine vesicular transporter (VAChT) and monoamine vesicular transporter type 2 (VMAT2) binding sites in postmortem basal ganglia samples from subjects with PSP. Comparison neurochemical measures included choline acetyltransferase (ChAT) enzyme activity and benzodiazepine (BZ) binding sites. RESULTS VAChT expressions and ChAT activities in caudate nucleus and putamen were markedly decreased in PSP, whereas BZ binding was unaffected, consistent with selective losses of striatal cholinergic interneurons. VMAT2 density was reduced significantly in the caudate nucleus, putamen, and substantia nigra pars compacta, consistent with degeneration of dopaminergic nigrostriatal projection neurons in PSP. In the globus pallidus, BZ receptor binding sites were reduced, whereas VMAT2 and VAChT binding sites were unchanged, indicating losses of intrinsic pallidal neurons and synapses. CONCLUSIONS These results confirm selective and marked degenerations of basal ganglia cholinergic and dopaminergic terminals in PSP. Striatal VAChT reduction may provide a unique neurochemical imaging marker for distinction of PSP from other types of basal ganglia neurodegeneration.
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Affiliation(s)
- Masahiko Suzuki
- Department of Radiology, Division of Nuclear Medicine, University of Michigan, Ann Arbor, USA
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Suzuki M, Desmond TJ, Albin RL, Frey KA. Vesicular neurotransmitter transporters in Huntington's disease: initial observations and comparison with traditional synaptic markers. Synapse 2001; 41:329-36. [PMID: 11494403 DOI: 10.1002/syn.1089] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Markers of identified neuronal populations have previously suggested selective degeneration of projection neurons in Huntington's disease (HD) striatum. Interpretations are, however, limited by effects of compensatory regulation and atrophy. Studies of the vesicular monoamine transporter type-2 (VMAT2) and of the vesicular acetylcholine transporter (VAChT) in experimental animals indicate that they are robust markers of presynaptic integrity and are not subject to regulation. We measured dopamine and acetylcholine vesicular transporters to characterize the selectivity of degeneration in HD striatum. Brains were obtained at autopsy from four HD patients and five controls. Autoradiography was used to quantify radioligand binding to VMAT2, VAChT, the dopamine plasmalemmal transporter (DAT), benzodiazepine (BZ) binding sites, and D2-type dopamine receptors. The activity of choline acetyltransferase (ChAT) was determined as an additional marker of cholinergic neurons. Autoradiograms were analyzed by video-assisted densitometry and assessment of atrophy was made from regional structural areas in the coronal projection. Striatal VMAT2, DAT, and VAChT concentrations were unchanged or increased, while D2 and BZ binding and ChAT activity were decreased in HD. After atrophy correction, all striatal binding sites were decreased. However, the decrease in ChAT activity was 3-fold greater than that of VAChT binding. In addition to degeneration of striatal projection neurons, there are losses of extrinsic nigrostriatal projections and of striatal cholinergic interneurons in HD on the basis of vesicular transporter measures. There is also markedly reduced expression of ChAT by surviving cholinergic striatal interneurons.
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Affiliation(s)
- M Suzuki
- Department of Radiology (Division of Nuclear Medicine), The University of Michigan, Ann Arbor, Michigan, USA
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21
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Skaddan MB, Kilbourn MR, Snyder SE, Sherman PS, Desmond TJ, Frey KA. Synthesis, (18)F-labeling, and biological evaluation of piperidyl and pyrrolidyl benzilates as in vivo ligands for muscarinic acetylcholine receptors. J Med Chem 2000; 43:4552-62. [PMID: 11087580 DOI: 10.1021/jm000305o] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series of 31 compounds based on the piperidyl or pyrrolidyl benzilate scaffold were prepared from methyl benzilate and 4-piperidinol, (R)-(+)-3-piperidinol, or (R)-(+)-3-pyrrolidinol. Amine substituents included alkyl and aralkyl groups. In vitro K(i) values ranged from 0.05 nM to >100 nM. (R)-N-(2-Fluoroethyl)-3-piperidyl benzilate (3-FEPB, 22, K(i) = 12.1 nM) and N-(2-fluoroethyl)-4-piperidyl benzilate (4-FEPB, 8, K(i) = 1. 83 nM) were selected for radiolabeling with fluorine-18. Using alkylation with 2-[(18)F]fluoroethyl triflate, 3-[(18)F]FEPB (42) and 4-[(18)F]FEPB (43) were produced in 7-9% radiochemical yield and >97% radiochemical purity. For in vivo studies, retention was moderate in mouse brain for 42; however, blocking with scopolamine showed that uptake was not muscarinic cholinergic receptor-mediated. Conversely, 43 exhibited high, receptor-mediated retention in mouse brain, with significant clearance after 1 h. These results suggest that 43 could have applications as an in vivo probe for measuring endogenous acetylcholine levels.
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Affiliation(s)
- M B Skaddan
- Departments of Radiology and Neurology, University of Michigan Medical School, Ann Arbor, Michigan 48109-0028, USA
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22
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Snyder SE, Sherman PS, Desmond TJ, Frey KA, Kilbourn MR. (−)-6′,7′-[11C]Dihydroroten-12α-ol ((−)-[11C]DHROL) forin vivo measurement of mitochondrial Complex I. J Labelled Comp Radiopharm 1999. [DOI: 10.1002/(sici)1099-1344(199907)42:7<641::aid-jlcr226>3.0.co;2-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Vander Borght TM, Sima AA, Kilbourn MR, Desmond TJ, Kuhl DE, Frey KA. [3H]methoxytetrabenazine: a high specific activity ligand for estimating monoaminergic neuronal integrity. Neuroscience 1995; 68:955-62. [PMID: 8577387 DOI: 10.1016/0306-4522(95)00167-h] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The properties as well as the distribution of high specific activity alpha-[O-methyl-3H]methyoxytetrabenazine binding to the synaptic vesicular monoamine transporter were studied autoradiographically in rat brain sections. Saturation analysis revealed [3H]methoxytetrabenazine interaction with a homogeneous population of striatal sites (Hill coefficient 1.00 +/- 0.05), with an apparent equilibrium dissociation binding constant of 3.9 +/- 0.4 nM and a maximal binding capacity of 1.2 +/- 0.1 fmol/micrograms protein. Highest levels of [3H]methoxytetrabenazine binding sites were observed in regions richly innervated by the monoamine systems. In the presence of 1 microM concentrations of a variety of competing drugs, only reserpine significantly inhibited [3H]methoxytetrabenazine binding. The presynaptic nigrostriatal location of [3H]methoxytetrabenazine binding was demonstrated by unilateral lesion of the median forebrain bundle with 6-hydroxydopamine. The resulting decrease of striatal [3H]methoxytetrabenazine binding showed an excellent correlation with tyrosine hydroxylase-positive neuron density in the substantia nigra pars compacta (r2 = 0.96; P < 0.001). The present studies demonstrate that in vitro [3H]methoxytetrabenazine binding is a reliable, quantitative marker of the synaptic vesicular monoamine transporter. Further, it is indicated that [3H]methoxytetrabenazine binding provides an accurate assessment of monoamine neuronal losses and may thus be of great value in future studies of neurodegenerative diseases.
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Affiliation(s)
- T M Vander Borght
- Department of Internal Medicine (Division of Nuclear Medicine), University of Michigan, Ann Arbor 48109-0028, USA
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Lalor FJ, Desmond TJ, Cotter GM, Shanahan CA, Ferguson G, Parvez M, Ruhl B. Formation of η2-aroyl, η1-halogenocarbyne or sterically crowded aryldiazenide ligands in the reactions of ring-substituted tricarbonyl[hydrotris(pyrazolyl)borato]-molybdate and -tungstate anions with arenediazonium cations and related oxidants. ACTA ACUST UNITED AC 1995. [DOI: 10.1039/dt9950001709] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Abstract
A family of receptor subtypes, defined either by molecular (m1-m5) or pharmacological (M1-M4) analysis, mediates muscarinic cholinergic neurotransmission in brain. The distribution and functions of the m3 receptor protein in brain and its relation to M3 ligand binding sites are poorly understood. To better characterize the native brain receptors, subtype-specific antibodies reactive with the putative third inner loops were used: (i) to measure the abundance of m3 protein and its regional distribution in rat brain by immunoprecipitation; (ii) to determine the cellular and subcellular distribution of m3 protein by light microscopic immunocytochemistry; and (iii) to compare the distribution of m3 immunoreactivity with the autoradiographic distribution of M3 binding sites labeled by [3H]4-diphenylacetoxy-N-methyl piperidine methioxide in the presence of antagonists selective for the other receptor binding sites. The m3 protein, measured by immunoprecipitation, accounted for 5-10% of total solubilized receptors in all brain regions studied. Immunocytochemistry also revealed a widespread distribution of m3-like immunoreactivity, and localized the subtype to discrete neuronal populations and distinct subcellular compartments. The distribution of m3 protein was consistent with the messenger RNA expression, and like M3 binding sites, the protein was enriched in limbic cortical regions, striatum, hippocampus, anterior thalamic nuclei, superior colliculus and pontine nuclei. However, m3 immunoreactivity and M3 binding were differentially localized in regions and lamina of cortex and hippocampus. The results confirm the presence of m3 protein in brain, its low abundance compared to other muscarinic receptor subtypes, and provide the first immunocytochemical map of its precise localization. The distribution of m3 suggests that it mediates a wide variety of cholinergic processes in brain, including possible roles in learning and memory, motor function and behavioral state control. However, since the distribution of the molecularly-defined receptor protein is distinct from the pharmacologically-defined M3 binding site, investigations of the functions of m3 in brain must await development of more selective ligands or use of non-pharmacological approaches.
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Affiliation(s)
- A I Levey
- Department of Neurology, Emory University School of Medicine, Atlanta, GA 30322
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26
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Siegel GJ, Desmond TJ. Effects of tetradecyl sulfate on electrophoretic resolution of kidney Na,K-ATPase catalytic subunit isoforms. J Biol Chem 1989; 264:4751-4. [PMID: 2538458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Inclusion of sodium tetradecyl sulfate in the Laemmli polyacrylamide gel electrophoresis system produces resolution of the kidney Na,K-ATPase catalytic subunit into a doublet and sharpens demarcation of catalytic subunit isoforms in NA,K-ATPase from brain.
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Affiliation(s)
- G J Siegel
- Department of Neurology, University of Michigan Medical Center, Ann Arbor 48109
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Siegel GJ, Desmond TJ. Effects of Tetradecyl Sulfate on Electrophoretic Resolution of Kidney Na,K-ATPase Catalytic Subunit Isoforms. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)83651-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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28
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Abstract
The myelin-deficient Shiverer (Shi/Shi) mutant mouse may be a useful model in assessing the dependence of brain (Na+ + K+)-ATPase concentration and composition on myelin membrane formation. Brain microsomal membranes from age-matched control (+/+) and Shiverer (Shi/Shi) mice were fractionated by differential centrifugation and sucrose gradient sedimentation. No reduction in (Na+ + K+)-ATPase specific activity was measured in whole homogenates, high- and low-speed fractions or gradient fractions from brains of Shi/Shi mice as compared to those of +/+ mice. In addition, sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting with antisera specific for mouse brain (Na+ + K+)-ATPase revealed no significant difference in catalytic subunit composition between fractions of +/+ and Shi/Shi brains. The similar results obtained for both +/+ and myelin-deficient Shi/Shi mice suggest that myelin contributes little to total brain (Na+ + K+)-ATPase.
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Affiliation(s)
- H J Sheedlo
- Department of Neurology, University of Michigan, Ann Arbor 48109
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29
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Abstract
The content and distribution of the membrane-bound enzyme (Na+ + K+)-ATPase in a rat cerebral C6 glioma was determined by immunocytochemistry, immunoblots and enzyme assay. In the C6 glioma cell culture (Na+ + K+)-ATPase activity was about 20% of (Mg2+ + Na+ + K+)-ATPase activity. However, (Mg2+ + Na+ + K+)-ATPase activity in the cerebral C6 gliomas was very close to Mg2+ baseline and not significantly increased by Na+ and K+. As shown by immunoblotting, (Na+ + K+)-ATPase catalytic subunit was detected in excised samples of control cerebrum and as a trace in the intracerebral portions of C6 glioma but not at all in the extracranial portions of C6 glioma or in C6 glioma cell culture. (Na+ + K+)-ATPase was not detected immunocytochemically in paraffin sections of the extracranial or intracerebral portions of rat cerebral C6 glioma. The absence of staining for (Na+ + K+)-ATPase clearly demarcated projections of glioma within normal brain. These results suggest that C6 glioma has little if any expression of (Na+ + K+)-ATPase in vitro or in vivo. The small amount of enzyme epitope in the intracerebral portions represents contamination by normal cerebrum in the extracts.
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Lalor FJ, Desmond TJ, Ferguson G, Siew PY. Co-ordination chemistry of arenediazoate anions: synthesis and X-ray crystallographic characterisation of η-cyclopentadienyl-(anti-p-nitrobenzenediazoato-N1)(triphenylphosphine)nickel(II), [Ni(η-C5H5)(PPh3)(ON2C6H4NO2-p)]. ACTA ACUST UNITED AC 1982. [DOI: 10.1039/dt9820001981] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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