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Auvity S, Vodovar D, Goutal S, Cisternino S, Chevillard L, Soyer A, Bottlaender M, Caillé F, Mégarbane B, Tournier N. Brain PET imaging using 11C-flumazenil and 11C-buprenorphine does not support the hypothesis of a mutual interaction between buprenorphine and benzodiazepines at the neuroreceptor level. J Cereb Blood Flow Metab 2024; 44:449-458. [PMID: 38097513 PMCID: PMC10870960 DOI: 10.1177/0271678x231221040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 11/20/2023] [Accepted: 11/20/2023] [Indexed: 02/16/2024]
Abstract
Among opioids, buprenorphine presents a favorable safety profile with a limited risk of respiratory depression. However, fatalities have been reported when buprenorphine is combined to a benzodiazepine. Potentiation of buprenorphine interaction with opioid receptors (ORs) with benzodiazepines, and/or vice versa, is hypothesized to explain this drug-drug interaction (DDI). The mutual DDI between buprenorphine and benzodiazepines was investigated at the neuroreceptor level in nonhuman primates (n = 4 individuals) using brain PET imaging and kinetic modelling. The binding potential (BPND) of benzodiazepine receptor (BzR) was assessed using 11C-flumazenil PET imaging before and after administration of buprenorphine (0.2 mg, i.v.). Moreover, the brain kinetics and receptor binding of buprenorphine were investigated in the same individuals using 11C-buprenorphine PET imaging before and after administration of diazepam (10 mg, i.v.). Outcome parameters were compared using a two-way ANOVA. Buprenorphine did not impact the plasma nor brain kinetics of 11C-flumazenil. 11C-flumazenil BPND was unchanged following buprenorphine exposure, in any brain region (p > 0.05). Similarly, diazepam did not impact the plasma or brain kinetics of 11C-buprenorphine. 11C-buprenorphine volume of distribution (VT) was unchanged following diazepam exposure, in any brain region (p > 0.05). To conclude, our PET imaging findings do not support a neuropharmacokinetic or neuroreceptor-related mechanism of the buprenorphine/benzodiazepine interaction.
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Affiliation(s)
- Sylvain Auvity
- Faculté de Pharmacie, Université Paris Cité, Inserm, UMRS-1144, Optimisation Thérapeutique en Neuropsychopharmacologie, 75006 Paris, France
| | - Dominique Vodovar
- Faculté de Pharmacie, Université Paris Cité, Inserm, UMRS-1144, Optimisation Thérapeutique en Neuropsychopharmacologie, 75006 Paris, France
- Réanimation Médicale et Toxicologique, Hôpital Lariboisière, Fédération de Toxicologie (APHP), 75010, Paris
| | - Sébastien Goutal
- Université Paris-Saclay, Inserm, CNRS, CEA, Laboratoire d’Imagerie Biomédicale Multimodale (BioMaps), Orsay, France
| | - Salvatore Cisternino
- Faculté de Pharmacie, Université Paris Cité, Inserm, UMRS-1144, Optimisation Thérapeutique en Neuropsychopharmacologie, 75006 Paris, France
| | - Lucie Chevillard
- Faculté de Pharmacie, Université Paris Cité, Inserm, UMRS-1144, Optimisation Thérapeutique en Neuropsychopharmacologie, 75006 Paris, France
| | - Amélie Soyer
- Université Paris-Saclay, Inserm, CNRS, CEA, Laboratoire d’Imagerie Biomédicale Multimodale (BioMaps), Orsay, France
| | - Michel Bottlaender
- Université Paris-Saclay, Inserm, CNRS, CEA, Laboratoire d’Imagerie Biomédicale Multimodale (BioMaps), Orsay, France
| | - Fabien Caillé
- Université Paris-Saclay, Inserm, CNRS, CEA, Laboratoire d’Imagerie Biomédicale Multimodale (BioMaps), Orsay, France
| | - Bruno Mégarbane
- Faculté de Pharmacie, Université Paris Cité, Inserm, UMRS-1144, Optimisation Thérapeutique en Neuropsychopharmacologie, 75006 Paris, France
- Réanimation Médicale et Toxicologique, Hôpital Lariboisière, Fédération de Toxicologie (APHP), 75010, Paris
| | - Nicolas Tournier
- Université Paris-Saclay, Inserm, CNRS, CEA, Laboratoire d’Imagerie Biomédicale Multimodale (BioMaps), Orsay, France
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Nagle VL, Ikotun OF, Henry KE. A Highlight on Dr. Julie C. Price: an Exceptional Career and a Candid Conversation on Diversity, Equity, and Inclusion. Mol Imaging Biol 2023; 25:265-270. [PMID: 35982280 DOI: 10.1007/s11307-022-01765-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Revised: 07/24/2022] [Accepted: 08/03/2022] [Indexed: 10/15/2022]
Affiliation(s)
- Veronica L Nagle
- Memorial Sloan Kettering Cancer Center, New York, NY, USA.,Weill Cornell Medical College, New York, NY, USA
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Caution!! Reappearance of remimazolam effect after a flumazenil bolus: a larger bolus of flumazenil and a lower total remimazolam clearance are higher risks. J Anesth 2023; 37:1-5. [PMID: 36114320 DOI: 10.1007/s00540-022-03107-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Accepted: 09/07/2022] [Indexed: 01/26/2023]
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Frankle WG, Robertson B, Maier G, Paris J, Asmonga D, May M, Himes ML, Mason NS, Mathis CA, Narendran R. An open-label positron emission tomography study to evaluate serotonin transporter occupancy following escalating dosing regimens of (R
)-(-)-O
-desmethylvenlafaxine and racemic O
-desmethylvenlafaxine. Synapse 2017; 72. [DOI: 10.1002/syn.22021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 11/30/2017] [Accepted: 12/04/2017] [Indexed: 11/09/2022]
Affiliation(s)
- W. Gordon Frankle
- Department of Psychiatry; NYU Langone Medical Center; New York New York
| | | | - Gary Maier
- MaierMetrics and Associates, LLC; Boston Massachusetts
| | - Jennifer Paris
- Department of Psychiatry; University of Pittsburgh; Pittsburgh Pennsylvania
| | - Deanna Asmonga
- Department of Psychiatry; University of Pittsburgh; Pittsburgh Pennsylvania
| | - Maureen May
- Department of Psychiatry; University of Pittsburgh; Pittsburgh Pennsylvania
| | - Michael L. Himes
- Department of Psychiatry; University of Pittsburgh; Pittsburgh Pennsylvania
| | - N. Scott Mason
- Department of Radiology; University of Pittsburgh; Pittsburgh Pennsylvania
| | - Chester A. Mathis
- Department of Radiology; University of Pittsburgh; Pittsburgh Pennsylvania
| | - Rajesh Narendran
- Department of Psychiatry; University of Pittsburgh; Pittsburgh Pennsylvania
- Department of Radiology; University of Pittsburgh; Pittsburgh Pennsylvania
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Vraka C, Mijailovic S, Fröhlich V, Zeilinger M, Klebermass EM, Wadsak W, Wagner KH, Hacker M, Mitterhauser M. Expanding LogP: Present possibilities. Nucl Med Biol 2017; 58:20-32. [PMID: 29309919 DOI: 10.1016/j.nucmedbio.2017.11.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 11/16/2017] [Accepted: 11/22/2017] [Indexed: 01/01/2023]
Abstract
INTRODUCTION Due to the high candidate exclusion rate during a drug development process, an early prediction of the pharmacokinetic behavior would be needed. Accordingly, high performance bioaffinity chromatography (HPBAC) approaches are growing in popularity, however, there is a lack of knowledge and no consensus about the relation between HPBAC measurements, in vivo distribution and blood brain barrier (BBB) penetration behavior. With respect to radiotracers, there is almost no reference data available for plasma protein binding (PPB), permeability (Pm) and the membrane coefficient (KIAM). Thus, this study was aimed at exploring the relevance of measuring PPB, Pm and KIAM for the prediction of BBB penetration. METHODS Measurements of %PPB, Pm and KIAM were performed using HPBAC. In total, 113 compounds were tested, 43 with brain uptake, 30 not showing brain uptake and 40 with known interactions with efflux transporters. Additionally, ClogP and HPLC logPowpH7.4 data were collected. RESULTS %PPB, KIAM, Pm and ClogP values were in the same range for each of the three groups. A significant difference was observed for the HPLC logPowpH7.4 between CNS penetrating drug group (CNSpos) and the non-penetrating drug group (CNSneg), as well as for the CNSneg towards the drug group interacting with efflux transporters (DRUGefflux). However, as the other experimental data, also the HPLC logPowpH7.4 showed a broad overlapping of the single values between the groupings. CONCLUSION Experimental reference values (logP, Pm, KIAM & PPB) of commonly used PET tracers and drugs showing different BBB penetration behavior are provided. The influence of the logP on brain uptake depends strongly on the selected method. However, using a single parameter (experimental or calculated) to predict BBB penetration or for the classification of drug groups is inexpedient.
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Affiliation(s)
- Chrysoula Vraka
- Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Vienna, Austria; Department for Nutritional Science, University of Vienna, Vienna, Austria
| | - Sanja Mijailovic
- Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Vienna, Austria; Ludwig Boltzmann Institute Applied Diagnostics, Vienna, Austria
| | - Vanessa Fröhlich
- Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Vienna, Austria
| | - Markus Zeilinger
- Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Vienna, Austria; Faculty of Engineering, University of Applied Sciences Wiener Neustadt, Wiener Neustadt, Austria
| | - Eva-Maria Klebermass
- Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Vienna, Austria
| | - Wolfgang Wadsak
- Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Vienna, Austria; Department of Inorganic Chemistry, University of Vienna, Vienna, Austria; CBmed, Graz, Austria
| | - Karl-Heinz Wagner
- Department for Nutritional Science, University of Vienna, Vienna, Austria
| | - Marcus Hacker
- Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Vienna, Austria
| | - Markus Mitterhauser
- Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Vienna, Austria; Ludwig Boltzmann Institute Applied Diagnostics, Vienna, Austria.
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Lopes Alves I, Vállez García D, Parente A, Doorduin J, Dierckx R, Marques da Silva AM, Koole M, Willemsen A, Boellaard R. Pharmacokinetic modeling of [ 11C]flumazenil kinetics in the rat brain. EJNMMI Res 2017; 7:17. [PMID: 28229437 PMCID: PMC5321646 DOI: 10.1186/s13550-017-0265-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Accepted: 02/15/2017] [Indexed: 11/12/2022] Open
Abstract
Background Preferred models for the pharmacokinetic analysis of [11C]flumazenil human studies have been previously established. However, direct translation of these models and settings to animal studies might be sub-optimal. Therefore, this study evaluates pharmacokinetic models for the quantification of [11C]flumazenil binding in the rat brain. Dynamic (60 min) [11C]flumazenil brain PET scans were performed in two groups of male Wistar rats (tracer dose (TD), n = 10 and pre-saturated (PS), n = 2). Time-activity curves from five regions were analyzed, including the pons (pseudo-reference region). Distribution volume (VT) was calculated using one- and two-tissue compartment models (1TCM and 2TCM) and spectral analysis (SA). Binding potential (BPND) was determined from full and simplified reference tissue models with one or two compartments for the reference tissue (FRTM, SRTM, and SRTM-2C). Model preference was determined by Akaike information criterion (AIC), while parameter agreement was assessed by linear regression, repeated measurements ANOVA and Bland-Altman plots. Results 1TCM and 2TCM fits of regions with high specific binding showed similar AIC, a preference for the 1TCM, and good VT agreement (0.1% difference). In contrast, the 2TCM was markedly preferred and necessary for fitting low specific-binding regions, where a worse VT agreement (17.6% difference) and significant VT differences between the models (p < 0.005) were seen. The PS group displayed results similar to those of low specific-binding regions. All reference models (FRTM, SRTM, and SRTM-2C) resulted in at least 13% underestimation of BPND. Conclusions Although the 1TCM was sufficient for the quantification of high specific-binding regions, the 2TCM was found to be the most adequate for the quantification of [11C]flumazenil in the rat brain based on (1) higher fit quality, (2) lower AIC values, and (3) ability to provide reliable fits for all regions. Reference models resulted in negatively biased BPND and were affected by specific binding in the pons of the rat.
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Affiliation(s)
- Isadora Lopes Alves
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - David Vállez García
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Andrea Parente
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Janine Doorduin
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Rudi Dierckx
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Ana Maria Marques da Silva
- Laboratory of Medical Imaging, School of Physics, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil
| | - Michel Koole
- Department of Nuclear Medicine and Molecular Imaging, KU Leuven, Leuven, Belgium
| | - Antoon Willemsen
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Ronald Boellaard
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
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Shaywitz BA, Shaywitz SE, Pugh KR, Skudlarski P, Fulbright RK, Constable R, Fletcher JM, Liberman AM, Shankweiler DP, Katz L, Bronen RA, Marchione KE, Lacadie C, Gore JC. The Functional Organization of Brain for Reading and Reading Disability (Dyslexia. Neuroscientist 2016. [DOI: 10.1177/107385849600200413] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Converging evidence from many lines of investigation now indicates that dyslexia (reading disability) represents a disorder affecting linguistic systems in brain. Furthermore, these studies point to deficits in one particular component of the language system—phonological processing—as the most severe, robust, and consistent findings in children and adults with dyslexia (the "phonological deficit" hypothesis). Until recently, the cerebral localization of those processes related to reading have been elusive, in no small measure because as uniquely human activities, language and reading can be studied only in humans. Within the last year, it has become possible to use functional magnetic resonance imaging (fMRI) to localize the component processes used in reading: orthography, phonology, and lexical-semantic processing. We found that in men phonological processing was lateralized to the left inferior frontal gyrus (IFG, Broca's area); in contrast, in women performance of a phonological task produced bilateral activation of this region. These findings provide the first clear evidence of sex differences in the functional organization of the brain for language and indicate that these differences exist at the level of phonological processing. Not only do these findings support and extend a long-held hypothesis suggesting that language functions are more likely to be highly lateralized in males, but, of particular relevance to the scientific study of reading and reading disability, these data suggest that the activation of the IFG region during the performance of a rhyming task may provide a neural "signature" for phonological processing, the core cognitive component in reading and reading disability. NEUROSCIENTIST 2:245-255, 1996
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Affiliation(s)
| | | | - Kenneth R. Pugh
- Department of Pediatrics, Haskins Laboratories, Department of Diagnostic Radiology (PS, RKF, RTC, RAB,
CL, JCG); Yale Umversity School of Medicine
| | - Pawel Skudlarski
- Haskins Laboratories, Department of Diagnostic Radiology (PS, RKF, RTC, RAB,
CL, JCG); Yale Umversity School of Medicine
| | - Robert K. Fulbright
- Haskins Laboratories, Department of Diagnostic Radiology (PS, RKF, RTC, RAB,
CL, JCG); Yale Umversity School of Medicine
| | - R.Todd Constable
- Haskins Laboratories, Department of Diagnostic Radiology (PS, RKF, RTC, RAB,
CL, JCG); Yale Umversity School of Medicine
| | - Jack M. Fletcher
- Department of Diagnostic Radiology (PS, RKF, RTC, RAB,
CL, JCG); Yale Umversity School of Medicine, Department of Pediatrics, University of Texas Medical
School-Houston
| | - Alvin M. Liberman
- Department of Diagnostic Radiology (PS, RKF, RTC, RAB,
CL, JCG); Yale Umversity School of Medicine
| | - Donald P. Shankweiler
- Department of Diagnostic Radiology (PS, RKF, RTC, RAB,
CL, JCG); Yale Umversity School of Medicine
| | - Leonard Katz
- Department of Diagnostic Radiology (PS, RKF, RTC, RAB,
CL, JCG); Yale Umversity School of Medicine
| | - Richard A. Bronen
- Haskins Laboratories, Department of Diagnostic Radiology (PS, RKF, RTC, RAB,
CL, JCG); Yale Umversity School of Medicine
| | | | - Cheryl Lacadie
- Haskins Laboratories, Department of Diagnostic Radiology (PS, RKF, RTC, RAB,
CL, JCG); Yale Umversity School of Medicine
| | - John C. Gore
- Haskins Laboratories, Department of Diagnostic Radiology (PS, RKF, RTC, RAB,
CL, JCG); Yale Umversity School of Medicine, Department of Applied Physics, Yale University
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Assmus F, Seelig A, Gobbi L, Borroni E, Glaentzlin P, Fischer H. Label-free assay for the assessment of nonspecific binding of positron emission tomography tracer candidates. Eur J Pharm Sci 2015; 79:27-35. [DOI: 10.1016/j.ejps.2015.08.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Revised: 08/02/2015] [Accepted: 08/25/2015] [Indexed: 10/23/2022]
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Frankle WG, Cho RY, Prasad KM, Mason NS, Paris J, Himes ML, Walker C, Lewis DA, Narendran R. In vivo measurement of GABA transmission in healthy subjects and schizophrenia patients. Am J Psychiatry 2015; 172:1148-59. [PMID: 26133962 PMCID: PMC5070491 DOI: 10.1176/appi.ajp.2015.14081031] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Postmortem studies in schizophrenia reveal alterations in gene products that regulate the release and extracellular persistence of GABA. However, results of in vivo studies of schizophrenia measuring total tissue GABA with magnetic resonance spectroscopy (MRS) have been inconsistent. Neither the postmortem nor the MRS studies directly address the physiological properties of GABA neurotransmission. The present study addresses this question through an innovative positron emission tomography (PET) paradigm. METHOD The binding of [(11)C]flumazenil, a benzodiazepine-specific PET radiotracer, was measured before and after administration of tiagabine (0.2 mg/kg of body weight), a GABA membrane transporter (GAT1) blocker, in 17 off-medication patients with schizophrenia and 22 healthy comparison subjects. Increased extracellular GABA, through GAT1 blockade, enhances the affinity of GABAA receptors for benzodiazepine ligands, detected as an increase in [(11)C]flumazenil tissue distribution volume (VT). RESULTS [(11)C]Flumazenil VT was significantly increased across all cortical brain regions in the healthy comparison group but not in the schizophrenia group. This lack of effect was most prominent in the antipsychotic-naive schizophrenia group. In this subgroup, [(11)C]flumazenil ΔVT in the medial temporal lobe was correlated with positive symptoms, and baseline [(11)C]flumazenil VT in the medial temporal lobe was negatively correlated with visual learning. In the healthy comparison group but not the schizophrenia group, [(11)C]flumazenil ΔVT was positively associated with gamma-band oscillation power. CONCLUSIONS This study demonstrates, for the first time, an in vivo impairment in GABA transmission in schizophrenia, most prominent in antipsychotic-naive individuals. The impairment in GABA transmission appears to be linked to clinical symptoms, disturbances in cortical oscillations, and cognition.
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Rami-Mark C, Berroterán-Infante N, Philippe C, Foltin S, Vraka C, Hoepping A, Lanzenberger R, Hacker M, Mitterhauser M, Wadsak W. Radiosynthesis and first preclinical evaluation of the novel norepinephrine transporter pet-ligand [(11)C]ME@HAPTHI. EJNMMI Res 2015; 5:113. [PMID: 26061602 PMCID: PMC4467816 DOI: 10.1186/s13550-015-0113-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 05/22/2015] [Indexed: 11/16/2022] Open
Abstract
Background The norepinephrine transporter (NET) has been demonstrated to be relevant to a multitude of neurological, psychiatric and cardiovascular pathologies. Due to the wide range of possible applications for PET imaging of the NET together with the limitations of currently available radioligands, novel PET tracers for imaging of the cerebral NET with improved pharmacological and pharmacodynamic properties are needed. Methods The present study addresses the radiosynthesis and first preclinical evaluation of the novel NET PET tracer [11C]Me@HAPTHI by describing its affinity, selectivity, metabolic stability, plasma free fraction, blood–brain barrier (BBB) penetration and binding behaviour in in vitro autoradiography. Results [11C]Me@HAPTHI was prepared and displayed outstanding affinity and selectivity as well as excellent in vitro metabolic stability, and it is likely to penetrate the BBB. Moreover, selective NET binding in in vitro autoradiography was observed in human brain and rat heart tissue samples. Conclusions All preclinical results and radiosynthetic key-parameters indicate that the novel benzothiadiazole dioxide-based PET tracer [11C]Me@HAPTHI is a feasible and improved NET radioligand and might prospectively facilitate clinical NET imaging. Electronic supplementary material The online version of this article (doi:10.1186/s13550-015-0113-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Christina Rami-Mark
- Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Vienna, Austria,
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Sahdeo S, Tomilov A, Komachi K, Iwahashi C, Datta S, Hughes O, Hagerman P, Cortopassi G. High-throughput screening of FDA-approved drugs using oxygen biosensor plates reveals secondary mitofunctional effects. Mitochondrion 2014; 17:116-25. [PMID: 25034306 DOI: 10.1016/j.mito.2014.07.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Revised: 06/11/2014] [Accepted: 07/01/2014] [Indexed: 10/25/2022]
Abstract
Repurposing of FDA-approved drugs with effects on mitochondrial function might shorten the critical path to mitochondrial disease drug development. We improved a biosensor-based assay of mitochondrial O2 consumption, and identified mitofunctional defects in cell models of LHON and FXTAS. Using this platform, we screened a 1600-compound library of clinically used drugs. The assay identified drugs known to affect mitochondrial function, such as metformin and decoquinate. We also identified several drugs not previously known to affect mitochondrial respiration including acarbose, metaraminol, gallamine triethiodide, and acamprosate. These previously unknown 'mitoactives' represent novel links to targets for mitochondrial regulation and potentially therapy, for mitochondrial disease.
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Affiliation(s)
- Sunil Sahdeo
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, 1089 Veterinary Medicine Drive, Davis, CA 95616, United States
| | - Alexey Tomilov
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, 1089 Veterinary Medicine Drive, Davis, CA 95616, United States
| | - Kelly Komachi
- Eon Research, 707 4th Street, Suite 305, Davis, CA 95616, United States
| | - Christine Iwahashi
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, 4455 Tupper Hall, Davis, CA 95616, United States
| | - Sandipan Datta
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, 1089 Veterinary Medicine Drive, Davis, CA 95616, United States
| | - Owen Hughes
- Eon Research, 707 4th Street, Suite 305, Davis, CA 95616, United States
| | - Paul Hagerman
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, 4455 Tupper Hall, Davis, CA 95616, United States
| | - Gino Cortopassi
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, 1089 Veterinary Medicine Drive, Davis, CA 95616, United States
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Zhu W, Li Q, Bai B, Conti PS, Leahy RM. Patlak image estimation from dual time-point list-mode PET data. IEEE TRANSACTIONS ON MEDICAL IMAGING 2014; 33:913-924. [PMID: 24710160 PMCID: PMC4209255 DOI: 10.1109/tmi.2014.2298868] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We investigate using dual time-point PET data to perform Patlak modeling. This approach can be used for whole body dynamic PET studies in which we compute voxel-wise estimates of Patlak parameters using two frames of data for each bed position. Our approach directly uses list-mode arrival times for each event to estimate the Patlak parametric image. We use a penalized likelihood method in which the penalty function uses spatially variant weighting to ensure a count independent local impulse response. We evaluate performance of the method in comparison to fractional changes in SUV values (%DSUV) between the two frames using Cramer Rao analysis and Monte Carlo simulation. Receiver operating characteristic (ROC) curves are used to compare performance in differentiating tumors relative to background based on the dynamic data sets. Using area under the ROC curve as a performance metric, we show superior performance of Patlak relative to %DSUV over a range of dynamic data sets and parameters. These results suggest that Patlak analysis may be appropriate for analysis of dual time-point whole body PET data and could lead to superior detection of tumors relative to %DSUV metrics.
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Affiliation(s)
- Wentao Zhu
- Signal and Image Processing Institute, University of Southern California, LA, CA 90089 USA
| | - Quanzheng Li
- Massachusetts General Hospital, Boston, MA, 02114 USA
| | - Bing Bai
- Department of Radiology, University of Southern California, LA, CA 90089 USA
| | - Peter S. Conti
- Department of Radiology, University of Southern California, LA, CA 90089 USA
| | - Richard M. Leahy
- Signal and Image Processing Institute, University of Southern California, LA, CA 90089 USA
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13
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Vivash L, Gregoire MC, Bouilleret V, Berard A, Wimberley C, Binns D, Roselt P, Katsifis A, Myers DE, Hicks RJ, O'Brien TJ, Dedeurwaerdere S. In vivo measurement of hippocampal GABAA/cBZR density with [18F]-flumazenil PET for the study of disease progression in an animal model of temporal lobe epilepsy. PLoS One 2014; 9:e86722. [PMID: 24466212 PMCID: PMC3897736 DOI: 10.1371/journal.pone.0086722] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 12/15/2013] [Indexed: 11/18/2022] Open
Abstract
Purpose Imbalance of inhibitory GABAergic neurotransmission has been proposed to play a role in the pathogenesis of temporal lobe epilepsy (TLE). This study aimed to investigate whether [18F]-flumazenil ([18F]-FMZ) PET could be used to non-invasively characterise GABAA/central benzodiazepine receptor (GABAA/cBZR) density and affinity in vivo in the post-kainic acid status epilepticus (SE) model of TLE. Methods Dynamic [18F]-FMZ -PET scans using a multi-injection protocol were acquired in four male wistar rats for validation of the partial saturation model (PSM). SE was induced in eight male Wistar rats (10 weeks of age) by i.p. injection of kainic acid (7.5–25 mg/kg), while control rats (n = 7) received saline injections. Five weeks post-SE, an anatomic MRI scan was acquired and the following week an [18F]-FMZ PET scan (3.6–4.6 nmol). The PET data was co-registered to the MRI and regions of interest drawn on the MRI for selected structures. A PSM was used to derive receptor density and apparent affinity from the [18F]-FMZ PET data. Key Findings The PSM was found to adequately model [18F]-FMZ binding in vivo. There was a significant decrease in hippocampal receptor density in the SE group (p<0.01), accompanied by an increase in apparent affinity (p<0.05) compared to controls. No change in cortical receptor binding was observed. Hippocampal volume reduction and cell loss was only seen in a subset of animals. Histological assessment of hippocampal cell loss was significantly correlated with hippocampal volume measured by MRI (p<0.05), but did not correlate with [18F]-FMZ binding. Significance Alterations to hippocampal GABAA/cBZR density and affinity in the post-kainic acid SE model of TLE are detectable in vivo with [18F]-FMZ PET and a PSM. These changes are independent from hippocampal cell and volume loss. [18F]-FMZ PET is useful for investigating the role that changes GABAA/cBZR density and binding affinity play in the pathogenesis of TLE.
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Affiliation(s)
- Lucy Vivash
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
| | - Marie-Claude Gregoire
- Department of LifeSciences, Australian Nuclear Science and Technology Organisation, Sydney, New South Wales, Australia
| | - Viviane Bouilleret
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
| | - Alexis Berard
- Department of LifeSciences, Australian Nuclear Science and Technology Organisation, Sydney, New South Wales, Australia
| | - Catriona Wimberley
- Department of LifeSciences, Australian Nuclear Science and Technology Organisation, Sydney, New South Wales, Australia
| | - David Binns
- The Centre for Molecular Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Peter Roselt
- The Centre for Molecular Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Andrew Katsifis
- Department of LifeSciences, Australian Nuclear Science and Technology Organisation, Sydney, New South Wales, Australia
| | - Damian E. Myers
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
| | - Rodney J. Hicks
- The Centre for Molecular Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Terence J. O'Brien
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
- * E-mail:
| | - Stefanie Dedeurwaerdere
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
- Department of Translational Neurosciences, University of Antwerp, Wilrijk, Belgium
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Wilson AA, Hicks JW, Sadovski O, Parkes J, Tong J, Houle S, Fowler CJ, Vasdev N. Radiosynthesis and evaluation of [¹¹C-carbonyl]-labeled carbamates as fatty acid amide hydrolase radiotracers for positron emission tomography. J Med Chem 2012; 56:201-9. [PMID: 23214511 PMCID: PMC3544278 DOI: 10.1021/jm301492y] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
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Fatty acid amide hydrolase (FAAH) plays a key role in
regulating
the tone of the endocannabinoid system. Radiotracers are required
to image and quantify FAAH activity in vivo. We have synthesized a
series of potent FAAH inhibitors encompassing two classes of N-alkyl-O-arylcarbamates and radiolabeled
eight of them with carbon-11. The [11C-carbonyl]-radiotracers were evaluated in vitro and ex vivo in rats as potential
FAAH imaging agents for positron emission tomography (PET). Both sets
of [11C]O-arylcarbamates showed good to
excellent brain penetration and an appropriate regional distribution.
Pretreatments with a FAAH inhibitor demonstrated that 80–95%
of brain uptake of radioactivity constituted binding of the radiotracers
to FAAH. Brain extraction measurements showed that binding to FAAH
was irreversible and kinetically different for the two classes of
carbamates. These promising results are discussed in terms of the
requirements of a suitable radiotracer for the in vivo imaging of
FAAH using PET.
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Affiliation(s)
- Alan A Wilson
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario M5T 1R8, Canada.
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15
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Harada N, Ohba H, Kakiuchi T, Tsukada H. Application of feedback-controlled bolus plus infusion (FC-B/I) method for quantitative PET imaging of dopamine transporters with [(18)F]β-CFT-FE in conscious monkey brain. Synapse 2012; 67:42-50. [PMID: 23042662 DOI: 10.1002/syn.21614] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Accepted: 10/03/2012] [Indexed: 01/03/2023]
Abstract
The competitive inhibition of dopamine transporters (DAT) with cocaine, a specific DAT inhibitor, was evaluated with a feedback-controlled bolus plus infusion (FC-B/I) method using animal positron emission tomography (PET) in the living brain of conscious monkey. 2β-Carbomethoxy-3β-(4-fluorophenyl)-8-(2-[(18)F]fluoroethyl) nortropane ([(18)F]β-CFT-FE; Harada et al. [2004] Synapse 54:37-45) was used for this study because it provided specific, fast, and reversible kinetic properties to DAT in the striatum. In FC-B/I method, the real-time image reconstruction was started just after intravenous bolus injection of [(18)F]β-CFT-FE to generate a time-activity curve in the striatum, and the infusion rate was adjusted to achieve an equilibrium state of the striatal radioactivity concentrations by means of a feedback-control algorithm. The first equilibrium state in the brain was reached within 20 min after the infusion start. Intravenous administration of cocaine at the doses of 0.02, 0.1, and 0.5 mg/kg shifted the equilibrium radioactivity level to the second equilibrium state in a dose-dependent manner, while no significant alterations was observed in the cerebellum. The present results demonstrated that the combined use of FC-B/I method and PET probe with fast kinetics like [(18)F]β-CFT-FE could be useful to assess the occupancy of drugs in the living brain with PET.
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Affiliation(s)
- Norihiro Harada
- Central Research Laboratory, Hamamatsu Photonics KK, 5000 Hirakuchi, Hamakita, Hamamatsu, Shizuoka 434-8601, Japan
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Laymon CM, Narendran R, Mason NS, Carney JP, Lopresti BJ, Mathis CA, Mountz JM, Sashin D, Frankle WG. Human biodistribution and dosimetry of the PET radioligand [¹¹C]flumazenil (FMZ). Mol Imaging Biol 2012; 14:115-22. [PMID: 21365327 DOI: 10.1007/s11307-011-0478-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
PURPOSE We measure the whole-body distribution of IV injected [¹¹C]Flumazenil (FMZ) as a function of time in adult subjects and determine the absorbed radiation doses. PROCEDURES After injection with 770 MBq of [¹¹C]FMZ (nominal), each of six subjects underwent nine consecutive whole body PET scans. Twelve source organs were identified using PET attenuation and emission images. Activity within each organ as a function of time was determined from the sequence of the nine PET scans. Source organ time activity curves were integrated and normalized by the injected dose to yield source organ residence times for the no voiding situation. Separate bladder residence-time calculations were performed for the cases of a 1- and a 2-h voiding interval. Using the source organ residence times as input, the program OLINDA/EXM (Stabin et al. in J Nucl Med. 46:1023-1027, 2005) was used to perform dosimetry calculations for the various body organs and for the whole body. RESULTS For the no voiding situation, the average whole-body radiation equivalent dose was 3.02 × 10⁻³ mSv/MBq of injected [¹¹C]FMZ. The average effective dose and effective dose equivalent was 7.57 × 10⁻³ and 1.12 × 10⁻² mSv MBq⁻¹, respectively. The organ receiving the highest equivalent dose was the urinary bladder wall with an average of 6.32 × 10⁻² mSv MBq⁻¹. CONCLUSION On average, the administration of less than 790 MBq (21 mCi) of [¹¹C]FMZ yields (no voiding model) an organ equivalent dose of under 50 mSv [the single dose limit for research studies under US regulations (21CFR361.1) to body organs other than blood forming organs, gonads or the lens of the eye] to all organs. Equivalent dose to the blood forming organs and gonads from a 790 MBq administered FMZ dose is well under the 30 mSv limit provided under 21CFR361.1. Additionally, administration of less than 1320 MBq (35.7 mCi) yields an effective dose [International Commission on Radiation Protection (ICRP) 60 tissue weighting scheme] of under 10 mSv, which is the ICRP IIb (minor to intermediate) risk category limit.
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Affiliation(s)
- Charles M Laymon
- Department of Radiology, UPMC/Presbyterian Hospital, University of Pittsburgh, Room B-938, 200 Lothrop St., Pittsburgh, PA 15213, USA.
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Frisch K, Jakobsen S, Sørensen M, Munk OL, Alstrup AKO, Ott P, Hofmann AF, Keiding S. [N-methyl-11C]cholylsarcosine, a novel bile acid tracer for PET/CT of hepatic excretory function: radiosynthesis and proof-of-concept studies in pigs. J Nucl Med 2012; 53:772-8. [PMID: 22454486 PMCID: PMC3390910 DOI: 10.2967/jnumed.111.098731] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
UNLABELLED Excretion of conjugated bile acids into bile is an essential function of the liver, and impairment of canalicular bile acid secretion leads to cholestatic liver injury. However, hepatic excretory function cannot be quantified in vivo because of the lack of suitable methods. Cholylsarcosine is an analog of the endogenous bile acid conjugate cholylglycine and exhibits characteristics in vivo that led us to hypothesize that the (11)C-labeled form, that is, [N-methyl-(11)C]cholylsarcosine ((11)C-cholylsarcosine), would be a suitable PET tracer for quantification of hepatic excretory function. METHODS A method for radiosynthesis of (11)C-cholylsarcosine was developed involving (11)C-methylation of glycine followed by conjugation with cholic acid. Blood-to-liver uptake and liver-to-bile excretion were investigated in vivo by dynamic (11)C-cholylsarcosine PET/CT of 2 anesthetized pigs. In pig 1, a second dynamic (11)C-cholylsarcosine PET/CT examination was preceded by a high dose of the endogenous bile acid conjugate cholyltaurine to investigate possible inhibition of the transhepatocellular transport of (11)C-cholylsarcosine. In pig 2, a second (11)C-cholylsarcosine administration was given to determine the biodistribution of the tracer by means of 5 successive whole-body PET/CT recordings. Possible formation of (11)C-metabolites was investigated by analysis of blood and bile samples from a third pig. RESULTS The radiochemical yield was 13% ± 3% (n = 7, decay-corrected) and up to 1.1 GBq of (11)C-cholylsarcosine was produced with a radiochemical purity greater than 99%. PET/CT studies showed rapid blood-to-liver uptake and liver-to-bile excretion of (11)C-cholylsarcosine, with radioactivity concentrations being more than 90 times higher in the bile ducts than in liver tissue. Cholyltaurine inhibited the transhepatocellular transport of (11)C-cholylsarcosine, indicating that the tracer is transported by one or more of the same hepatic transporters as cholyltaurine. (11)C-cholylsarcosine underwent an enterohepatic circulation and reappeared in liver tissue and bile ducts after approximately 70 min. There were no detectable (11)C-metabolites in the plasma or bile samples, indicating that the novel conjugated bile acid (11)C-cholylsarcosine was not metabolized in the liver or in the intestines. The effective absorbed dose of (11)C-cholylsarcosine was 4.4 μSv/MBq. CONCLUSION We have synthesized a novel conjugated bile acid analog, (11)C-cholylsarcosine, and PET/CT studies on anesthetized pigs showed that the hepatic handling of tracer uptake from blood and excretion into the bile was comparable to that for the endogenous bile acid cholyltaurine. This tracer may be valuable for future studies of normal and pathologic hepatic excretory functions in humans.
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Affiliation(s)
- Kim Frisch
- PET Center, Aarhus University Hospital, Aarhus, Denmark.
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18
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Frankle WG, Cho RY, Mason NS, Chen CM, Himes M, Walker C, Lewis DA, Mathis CA, Narendran R. [11C]flumazenil binding is increased in a dose-dependent manner with tiagabine-induced elevations in GABA levels. PLoS One 2012; 7:e32443. [PMID: 22384252 PMCID: PMC3288104 DOI: 10.1371/journal.pone.0032443] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Accepted: 01/26/2012] [Indexed: 01/14/2023] Open
Abstract
Evidence indicates that synchronization of cortical activity at gamma-band frequencies, mediated through GABA-A receptors, is important for perceptual/cognitive processes. To study GABA signaling in vivo, we recently used a novel positron emission tomography (PET) paradigm measuring the change in binding of the benzodiazepine (BDZ) site radiotracer [11C]flumazenil associated with increases in extracellular GABA induced via GABA membrane transporter (GAT1) blockade with tiagabine. GAT1 blockade resulted in significant increases in [11C]flumazenil binding potential (BPND) over baseline in the major functional domains of the cortex, consistent with preclinical studies showing that increased GABA levels enhance the affinity of GABA-A receptors for BDZ ligands. In the current study we sought to replicate our previous results and to further validate this approach by demonstrating that the magnitude of increase in [11C]flumazenil binding observed with PET is directly correlated with tiagabine dose. [11C]flumazenil distribution volume (VT) was measured in 18 healthy volunteers before and after GAT1 blockade with tiagabine. Two dose groups were studied (n = 9 per group; Group I: tiagabine 0.15 mg/kg; Group II: tiagabine 0.25 mg/kg). GAT1 blockade resulted in increases in mean (± SD) [11C]flumazenil VT in Group II in association cortices (6.8±0.8 mL g−1 vs. 7.3±0.4 mL g−1;p = 0.03), sensory cortices (6.7±0.8 mL g−1 vs. 7.3±0.5 mL g−1;p = 0.02) and limbic regions (5.2±0.6 mL g−1 vs. 5.7±0.3 mL g−1;p = 0.03). No change was observed at the low dose (Group I). Increased orbital frontal cortex binding of [11C]flumazenil in Group II correlated with the ability to entrain cortical networks (r = 0.67, p = 0.05) measured via EEG during a cognitive control task. These data provide a replication of our previous study demonstrating the ability to measure in vivo, with PET, acute shifts in extracellular GABA.
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Affiliation(s)
- W Gordon Frankle
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
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19
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Frankle WG, Cho RY, Narendran R, Mason NS, Vora S, Litschge M, Price JC, Lewis DA, Mathis CA. Tiagabine increases [11C]flumazenil binding in cortical brain regions in healthy control subjects. Neuropsychopharmacology 2009; 34:624-33. [PMID: 18615011 PMCID: PMC2754778 DOI: 10.1038/npp.2008.104] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Accumulating evidence indicates that synchronization of cortical neuronal activity at gamma-band frequencies is important for various types of perceptual and cognitive processes and that GABA-A receptor-mediated transmission is required for the induction of these network oscillations. In turn, the abnormalities in GABA transmission postulated to play a role in psychiatric conditions such as schizophrenia might contribute to the cognitive deficits seen in this illness. We measured the ability to increase GABA in eight healthy subjects by comparing the binding of [(11)C]flumazenil, a positron emission tomography (PET) radiotracer specific for the benzodiazepine (BDZ) site, at baseline and in the presence of an acute elevation in GABA levels through the blockade of the GABA membrane transporter (GAT1). Preclinical work suggests that increased GABA levels enhance the affinity of GABA-A receptors for BDZ ligands (termed 'GABA shift'). Theoretically, such an increase in the affinity of GABA-A receptors should be detected as an increase in the binding of a GABA-A BDZ-receptor site-specific PET radioligand. GAT1 blockade resulted in significant increases in mean (+/- SD) [(11)C]flumazenil-binding potential (BP(ND)) over baseline in brain regions representing the major functional domains of the cerebral cortex: association cortex +15.2+/-20.2% (p=0.05), sensory cortex +13.5+/-15.5% (p=0.03) and limbic (medial temporal lobe, MTL) +16.4+/-20.2% (p=0.03). The increase in [(11)C]flumazenil-BP(ND) was not accounted for by differences in the plasma-free fraction (f(P); paired t-test p=0.24) or changes in the nonspecific binding (pons V(T), p=0.73). Moreover, the ability to increase GABA strongly predicted (r=0.85, p=0.015) the ability to entrain cortical networks, measured through EEG gamma synchrony during a cognitive control task in these same subjects. Although additional studies are necessary to further validate this technique, these data provide preliminary evidence of the ability to measure in vivo, with PET, acute fluctuations in extracellular GABA levels and provide the first in vivo documentation of a relationship between GABA neurotransmission and EEG gamma-band power in humans.
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Affiliation(s)
- W Gordon Frankle
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA 15213, USA.
| | - Raymond Y Cho
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
| | - Rajesh Narendran
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA,Department of Radiology, University of Pittsburgh, Pittsburgh, PA, USA
| | - N Scott Mason
- Department of Radiology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Shivangi Vora
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
| | - Maralee Litschge
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
| | - Julie C Price
- Department of Radiology, University of Pittsburgh, Pittsburgh, PA, USA
| | - David A Lewis
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA,Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
| | - Chester A Mathis
- Department of Radiology, University of Pittsburgh, Pittsburgh, PA, USA
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Odano I, Halldin C, Karlsson P, Varrone A, Airaksinen AJ, Krasikova RN, Farde L. [18F]flumazenil binding to central benzodiazepine receptor studies by PET--quantitative analysis and comparisons with [11C]flumazenil. Neuroimage 2008; 45:891-902. [PMID: 19136064 DOI: 10.1016/j.neuroimage.2008.12.005] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2008] [Revised: 11/25/2008] [Accepted: 12/01/2008] [Indexed: 12/13/2022] Open
Abstract
[(11)C]flumazenil is the reference radioligand for Positron Emission Tomography (PET) studies of central benzodiazepine (BZ) receptors. Fluorine is available in the flumazenil molecule and [(18)F]flumazenil has recently been prepared. The aim of the present PET-study in 8 male subjects was to examine the binding of [(18)F]flumazenil in the human brain by direct comparison with [(11)C]flumazenil. Each subject participated in two 93-minute PET-measurements with [(11)C]flumazenil and [(18)F]flumazenil, respectively. Data were analyzed using compartment models with metabolite-corrected arterial plasma input and reference tissue models using the pons as reference region. There was no evident difference between the kinetic behaviors of the two ligands. Overall, the noise in the time activity curves for [(18)F]flumazenil was lower at late time points, and the variance of the kinetic parameters was lower than for [(11)C]flumazenil. In BZ receptor rich regions, such as the neocortex, the 3-compartment model was statistically favored, whereas the 2-compartment model was favored in the pons. Binding potential values obtained by the reference tissue models were in good agreement with those obtained by the kinetic analysis. There was no support for the presence of specific binding in the pons. In conclusion, the binding and the kinetic behavior of [(11)C]flumazenil and [(18)F]flumazenil were similar. The present analysis supports the use of pons as reference region in simplified protocols without arterial blood sampling. [(18)F]flumazenil should thus be an excellent choice for applied studies at centers not having a cyclotron.
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Affiliation(s)
- Ikuo Odano
- Department of Clinical Neuroscience, Karolinska Institute, Stockholm, Sweden.
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Summerfield SG, Lucas AJ, Porter RA, Jeffrey P, Gunn RN, Read KR, Stevens AJ, Metcalf AC, Osuna MC, Kilford PJ, Passchier J, Ruffo AD. Toward an improved prediction of humanin vivobrain penetration. Xenobiotica 2008; 38:1518-35. [DOI: 10.1080/00498250802499459] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Rosso L, Gee AD, Gould IR. Ab initiocomputational study of positron emission tomography ligands interacting with lipid molecule for the prediction of nonspecific binding. J Comput Chem 2008; 29:2397-405. [DOI: 10.1002/jcc.20972] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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23
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Klumpers UMH, Veltman DJ, Boellaard R, Comans EF, Zuketto C, Yaqub M, Mourik JEM, Lubberink M, Hoogendijk WJG, Lammertsma AA. Comparison of plasma input and reference tissue models for analysing [(11)C]flumazenil studies. J Cereb Blood Flow Metab 2008; 28:579-87. [PMID: 17928801 DOI: 10.1038/sj.jcbfm.9600554] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A single-tissue compartment model with plasma input is the established method for analysing [(11)C]flumazenil ([(11)C]FMZ) studies. However, arterial cannulation and measurement of metabolites are time-consuming. Therefore, a reference tissue approach is appealing, but this approach has not been fully validated for [(11)C]FMZ. Dynamic [(11)C]FMZ positron emission tomography scans with arterial blood sampling were performed in nine drug-free depressive patients and eight healthy subjects. Regions of interest were defined on co-registered magnetic resonance imaging scans and projected onto dynamic [(11)C]FMZ images. Using a Hill-type metabolite function, single (1T) and reversible two-tissue (2T) compartmental models were compared. Simplified reference tissue model (SRTM) and full reference tissue model (FRTM) were investigated using both pons and (centrum semiovale) white matter as reference tissue. The 2T model provided the best fit in 59% of cases. Two-tissue V(T) values were on average 1.6% higher than 1T V(T) values. Owing to the higher rejection rate of 2T fits (7.3%), the 1T model was selected as plasma input method of choice. SRTM was superior to FRTM, irrespective whether pons or white matter was used as reference tissue. BP(ND) values obtained with SRTM correlated strongly with 1T V(T) (r=0.998 and 0.995 for pons and white matter, respectively). Use of white matter as reference tissue resulted in 5.5% rejected fits, primarily in areas with intermediate receptor density. No fits were rejected using pons as reference tissue. Pons produced 23% higher BP(ND) values than white matter. In conclusion, for most clinical studies, SRTM with pons as reference tissue can be used for quantifying [(11)C]FMZ binding.
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Affiliation(s)
- Ursula M H Klumpers
- Department of Psychiatry, VU University Medical Centre, Amsterdam, The Netherlands.
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Weerts EM, Kim YK, Wand GS, Dannals RF, Lee JS, Frost JJ, McCaul ME. Differences in delta- and mu-opioid receptor blockade measured by positron emission tomography in naltrexone-treated recently abstinent alcohol-dependent subjects. Neuropsychopharmacology 2008; 33:653-65. [PMID: 17487229 DOI: 10.1038/sj.npp.1301440] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Blockade of brain mu-opioid receptor (mu-OR) and delta-opioid receptor (delta-OR) was investigated in recently abstinent alcohol-dependent subjects (N=21) maintained on naltrexone. Subjects completed a 19-day inpatient protocol, which included alcohol abstinence followed by naltrexone treatment (50 mg) on days 15-19. Blood samples were collected after the first administration of naltrexone to evaluate serum levels of naltrexone and 6-beta-naltrexol. Regional brain mu-OR binding potential (BP) and delta-OR Ki was measured using [11C]carfentanil (CAR) positron emission tomography (PET) and [11C]methyl naltrindole ([11C]MeNTI) PET, respectively, before (day 5) and during naltrexone treatment (day 18). Naltrexone inhibition of [11C]CAR BP was near maximal across all brain regions of interest with little variability across subjects (mean+SD% inhibition=94.9+4.9%). Naltrexone only partially inhibited the [11C]MeNTI Ki and there was more variability across subjects (mean+SD% inhibition=21.1+14.49%). Peak serum levels of naltrexone were positively correlated with % inhibition of delta-OR Ki in neocortex and basal ganglia. Peak serum levels of naltrexone were not correlated with % inhibition of mu-OR BP. Peak levels of 6-beta-naltrexol were not significantly correlated with % inhibition of mu-OR BP or delta-OR Ki. Thus, the FDA recommended therapeutic dose of naltrexone was sufficient to produce near complete inhibition of the mu-OR in recently abstinent alcohol dependent subjects. The lower percent inhibition of delta-OR and greater variability in delta-OR blockade by naltrexone across subjects may contribute to individual differences in treatment outcomes to naltrexone. Further investigations on the relationship between individual differences in delta-OR blockade by naltrexone and clinical outcomes should be explored.
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Affiliation(s)
- Elise M Weerts
- Department of Radiology, The Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA.
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Ginovart N, Meyer JH, Boovariwala A, Hussey D, Rabiner EA, Houle S, Wilson AA. Positron emission tomography quantification of [11C]-harmine binding to monoamine oxidase-A in the human brain. J Cereb Blood Flow Metab 2006; 26:330-44. [PMID: 16079787 DOI: 10.1038/sj.jcbfm.9600197] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This article describes the kinetic modeling of [(11)C]-harmine binding to monoamine oxidase A (MAO-A) binding sites in the human brain using positron emission tomography (PET). Positron emission tomography studies were performed in healthy volunteers at placebo conditions and after treatment with clinical doses of moclobemide. In either condition, a two-tissue compartment model (2CM) provided better fits to the data than a one-tissue model. Estimates of k(3)/k(4) values from an unconstrained 2CM were highly variable. In contrast, estimates of the specifically bound radioligand distribution volume (DV(B)) from an unconstrained 2CM were exceptionally stable, correlated well with the known distribution of MAO-A in the brain (cerebellum <frontal cortex approximately putamen <temporal cortex approximately cingulate <thalamus) and thus provided reliable indices of MAO-A density. Total distribution volume (DV) values were also highly stable and not different from those estimated with the Logan approach. Fixing the DV of free and nonspecifically bound radiotracer (DV(F + NS)) or coupling DV(F + NS) between brain regions enabled more stable estimates of k(3)/k(4) as compared with an unconstrained 2CM. Moclobemide treatment leads to a 64% to 79% MAO-A blockade across brain regions, a result that supports the specificity of [(11)C]-harmine binding to MAO-A. The stability and reliability of DV(B) values obtained from an unconstrained 2CM, together with the computational simplicity associated with this method, support the use of DV(B) as an appropriate outcome measure for [(11)C]-harmine. These results indicate the suitability of using [(11)C]-harmine for quantitative evaluation of MAO-A densities using PET and should enable further studies of potential MAO-A dysregulation in several psychiatric and neurologic illnesses.
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Affiliation(s)
- Nathalie Ginovart
- PET Centre, Centre for Addiction and Mental Health, Toronto, Canada.
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Liefaard LC, Ploeger BA, Molthoff CFM, Boellaard R, Lammertsma AA, Danhof M, Voskuyl RA. Population Pharmacokinetic Analysis for Simultaneous Determination of B max and K D In Vivo by Positron Emission Tomography. Mol Imaging Biol 2005; 7:411-21. [PMID: 16328648 DOI: 10.1007/s11307-005-0022-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
PURPOSE Changes in GABA(A)-receptor density and affinity play an important role in many forms of epilepsy. A novel approach, using positron emission tomography (PET) and [C-11]flumazenil ([C-11]FMZ), was developed for simultaneous estimation of GABA(A)-receptor properties, characterized by B (max) and K (D). PROCEDURES Following an injection of [C-11]FMZ (dose range: 1-2,000 mug) to 21 rats, concentration time curves of FMZ in brain (using PET) and blood (using HPLC-UV) were analyzed simultaneously using a population pharmacokinetic (PK) model, containing expressions to describe the time course of the plasma concentration (including distribution to the body), the brain distribution, and the specific binding within the brain. RESULTS Application of this method in control rats resulted in estimates of B (max) and K (D) (14.5 +/- 3.7 ng/ml and 4.68 +/- 1.5 ng/ml, respectively). CONCLUSIONS The proposed population PK model allowed for simultaneous estimation of B (max) and K (D) for a group of animals using single injection PET experiments per animal.
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Affiliation(s)
- Lia C Liefaard
- Division of Pharmacology, LACDR, Leiden University, P.O. Box 9502, 2300 RA, Leiden, The Netherlands
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Wilson AA, McCormick P, Kapur S, Willeit M, Garcia A, Hussey D, Houle S, Seeman P, Ginovart N. Radiosynthesis and evaluation of [11C]-(+)-4-propyl-3,4,4a,5,6,10b-hexahydro-2H-naphtho[1,2-b][1,4]oxazin-9-ol as a potential radiotracer for in vivo imaging of the dopamine D2 high-affinity state with positron emission tomography. J Med Chem 2005; 48:4153-60. [PMID: 15943487 DOI: 10.1021/jm050155n] [Citation(s) in RCA: 199] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In vivo imaging of dopamine D2 receptors with agonist (as opposed to the more commonly employed antagonist) radiotracers could provide important information on the high-affinity (functional) state of the D2 receptor in illnesses such as schizophrenia, movement disorders, and addictions. We report here the radiosynthesis and evaluation of the potent D2 agonist (+)-4-propyl-3,4,4a,5,6,10b-hexahydro-2H-naphtho[1,2-b][1,4]oxazin-9-ol, (+)-3, labeled with carbon-11, as a potential radiotracer for imaging the high-affinity state of dopamine D2 receptors with positron emission tomography (PET). [(11)C]-(+)-3 was reliably synthesized in the quantities and at the specific activities and radiochemical purities required for human PET studies. Ex vivo biodistribution studies in rat brain demonstrated that [(11)C]-(+)-3 crossed the blood-brain barrier readily and had an appropriate regional brain distribution for a radiotracer that maps dopamine D2 receptors. The binding of [(11)C]-(+)-3 was saturable and demonstrated an excellent signal-to-noise ratio as measured by its striatum-to-cerebellum ratio of 5.6, 60 min postinjection. The binding was highly stereospecific, and blocking and displacement studies were consistent with selective and specific binding to the dopamine D2 receptors. Further, [(11)C]-(+)-3 showed marked and appropriate sensitivity to both increases and decreases in the levels of endogenous dopamine. Brain radioactive metabolite and physicochemical measurements are in full accord with the desired properties of a neuroreceptor imaging agent for PET. All of the above, coupled with the documented full D2 agonistic properties of (+)-3, strongly indicate that [(11)C]-(+)-3 is a leading candidate radiotracer for the imaging of the dopamine D2 high-affinity state using PET in human subjects.
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Affiliation(s)
- Alan A Wilson
- PET Centre, Centre for Addiction and Mental Health and Department of Psychiatry, University of Toronto, Ontario, Canada.
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28
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Slifstein M, Hwang DR, Huang Y, Guo N, Sudo Y, Narendran R, Talbot P, Laruelle M. In vivo affinity of [18F]fallypride for striatal and extrastriatal dopamine D2 receptors in nonhuman primates. Psychopharmacology (Berl) 2004; 175:274-86. [PMID: 15024551 DOI: 10.1007/s00213-004-1830-x] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
RATIONALE [18F]Fallypride is a new and promising radiotracer, suitable for imaging D2 receptors with Positron Emission Tomography (PET) in both striatal and extrastriatal regions. The high signal to noise ratio of [18F]fallypride has been attributed to its high affinity for D2 receptors (K(D) of 0.03 nM, measured in vitro at room temperature). OBJECTIVES We sought to further characterize this tracer in terms of its in vivo affinity, possible affinity differences between brain regions and dependence of in vitro affinity on temperature. METHODS PET scans were performed in baboons over a wide range of concentrations to measure the in vivo K(D) of [18F]fallypride in striatal and extrastriatal regions. Several analytical approaches were used, including nonlinear kinetic modeling and equilibrium methods. Also, in vitro assays were performed at 22 and 37 degrees C. RESULTS No significant differences in the in vivo K(D) were detected between regions. In vivo K(D) of [18F]fallypride was 0.22+/-0.05 nM in striatum, 0.17+/-0.05 nM in thalamus, and 0.21+/-0.07 nM in hippocampus. These values were intermediate between in vitro K(D) measured at 22 (0.04+/-0.03 nM) and 37 degrees (2.03+/-1.07 nM). CONCLUSION The in vivo affinity of [18F]fallypride was not as high as previously estimated from in vitro values. This property might contribute to the favorable kinetic properties of the tracer. The in vivo affinity was similar between striatal and extrastriatal regions. This result indicates that the measured regional in vivo affinities of this tracer are not affected by putative regional differences in endogenous dopamine, and that [18F]fallypride is an appropriate tool to provide unbiased estimates of the occupancy of D2 receptors by antipsychotic drugs in striatal and extrastriatal regions.
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Affiliation(s)
- Mark Slifstein
- Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York, NY, USA.
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29
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Bailer UF, Price JC, Meltzer CC, Mathis CA, Frank GK, Weissfeld L, McConaha CW, Henry SE, Brooks-Achenbach S, Barbarich NC, Kaye WH. Altered 5-HT(2A) receptor binding after recovery from bulimia-type anorexia nervosa: relationships to harm avoidance and drive for thinness. Neuropsychopharmacology 2004; 29:1143-55. [PMID: 15054474 PMCID: PMC4301578 DOI: 10.1038/sj.npp.1300430] [Citation(s) in RCA: 130] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Several lines of evidence suggest that a disturbance of serotonin neuronal pathways may contribute to the pathogenesis of anorexia nervosa (AN) and bulimia nervosa (BN). This study applied positron emission tomography (PET) to investigate the brain serotonin 2A (5-HT(2A)) receptor, which could contribute to disturbances of appetite and behavior in AN and BN. To avoid the confounding effects of malnutrition, we studied 10 women recovered from bulimia-type AN (REC AN-BN, > 1 year normal weight, regular menstrual cycles, no binging, or purging) compared with 16 healthy control women (CW) using PET imaging and a specific 5-HT(2A) receptor antagonist, [18F]altanserin. REC AN-BN women had significantly reduced [18F]altanserin binding potential relative to CW in the left subgenual cingulate, the left parietal cortex, and the right occipital cortex. [18F]altanserin binding potential was positively related to harm avoidance and negatively related to novelty seeking in cingulate and temporal regions only in REC AN-BN subjects. In addition, REC AN-BN had negative relationships between [18F]altanserin binding potential and drive for thinness in several cortical regions. In conclusion, this study extends research suggesting that altered 5-HT neuronal system activity persists after recovery from bulimia-type AN, particularly in subgenual cingulate regions. Altered 5-HT neurotransmission after recovery also supports the possibility that this may be a trait-related disturbance that contributes to the pathophysiology of eating disorders. It is possible that subgenual cingulate findings are not specific for AN-BN, but may be related to the high incidence of lifetime major depressive disorder diagnosis in these subjects.
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Affiliation(s)
- Ursula F Bailer
- Department of Psychiatry, School of Medicine, University of Pittsburgh, Western Psychiatric Institute and Clinic, Pittsburgh, PA, USA
- Department of General Psychiatry, University Hospital of Psychiatry, Medical University of Vienna, Vienna, Austria
| | - Julie C Price
- Department of Radiology, School of Medicine, Presbyterian University Hospital, University of Pittsburgh, Pittsburgh, PA, USA
| | - Carolyn C Meltzer
- Department of Psychiatry, School of Medicine, University of Pittsburgh, Western Psychiatric Institute and Clinic, Pittsburgh, PA, USA
- Department of Radiology, School of Medicine, Presbyterian University Hospital, University of Pittsburgh, Pittsburgh, PA, USA
| | - Chester A Mathis
- Department of Radiology, School of Medicine, Presbyterian University Hospital, University of Pittsburgh, Pittsburgh, PA, USA
| | - Guido K Frank
- Department of Psychiatry, School of Medicine, University of Pittsburgh, Western Psychiatric Institute and Clinic, Pittsburgh, PA, USA
| | - Lisa Weissfeld
- Department of Biostatistics, University of Pittsburgh, Pittsburgh, PA, USA
| | - Claire W McConaha
- Department of Psychiatry, School of Medicine, University of Pittsburgh, Western Psychiatric Institute and Clinic, Pittsburgh, PA, USA
| | - Shannan E Henry
- Department of Psychiatry, School of Medicine, University of Pittsburgh, Western Psychiatric Institute and Clinic, Pittsburgh, PA, USA
| | - Sarah Brooks-Achenbach
- Department of Psychiatry, School of Medicine, University of Pittsburgh, Western Psychiatric Institute and Clinic, Pittsburgh, PA, USA
| | - Nicole C Barbarich
- Department of Psychiatry, School of Medicine, University of Pittsburgh, Western Psychiatric Institute and Clinic, Pittsburgh, PA, USA
| | - Walter H Kaye
- Department of Psychiatry, School of Medicine, University of Pittsburgh, Western Psychiatric Institute and Clinic, Pittsburgh, PA, USA
- Correspondence: WH Kaye, Western Psychiatric Institute and Clinic, University of Pittsburgh, Iroquois Building, Suite 600, 3811 O’Hara Street, Pittsburgh, PA 15213, USA, Tel: + 1-412-647-9845, Fax: + 1-412-647-9740,
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Lucignani G, Panzacchi A, Bosio L, Moresco RM, Ravasi L, Coppa I, Chiumello G, Frey K, Koeppe R, Fazio F. GABAA receptor abnormalities in Prader–Willi syndrome assessed with positron emission tomography and [11C]flumazenil. Neuroimage 2004; 22:22-8. [PMID: 15109994 DOI: 10.1016/j.neuroimage.2003.10.050] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2003] [Revised: 10/02/2003] [Accepted: 10/02/2003] [Indexed: 10/26/2022] Open
Abstract
Prader-Willi syndrome (PWS) is a multi-system disorder characterized clinically by abnormal mental and physical development. PWS patients have a deletion in an imprinted region on paternal chromosome 15 (15q11-13), maternal disomy for this segment, or rarely, a chromosomal imprinting center deletion that gives rise to suppression of the equivalent paternal genes. Within the affected segment of chromosome 15 are genes encoding the alpha(5), beta(3) and gamma(3) subunits of the gamma-aminobutyric acid type-A (GABA(A)) receptor. Therefore, altered neurobehavioral function could arise in PWS due directly to altered GABA(A) receptor composition and expression, or alternatively, from brain developmental and maturational effects of these or other genes in the imprinted region. The aim of the present study was to assess cerebral GABA(A) receptors in PWS with the use of positron emission tomography of the benzodiazepine binding site employing [11C]flumazenil ([11C]FMZ). A reduction in [11C]FMZ binding was found predominantly in the cingulate, frontal and temporal neocortices and insula in six adult PWS patients compared to nine normal subjects. A possible role for the deleted beta(3) subunit gene in PWS is supported in part by the wide cortical distribution of its mRNA expression and the effects of experimental knockouts on benzodiazepine binding described in prior studies. Altered GABA(A) receptor composition or number in these cortical regions may account for neurobehavioral abnormalities in PWS including mild mental retardation, poor impulse control, and impaired responses to somatic pain.
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Affiliation(s)
- Giovanni Lucignani
- Istituto Europeo di Oncologia, Radiotherapy Department, Università degli Studi di Milano, via Ripamonti 435, 20141 Milan, Italy.
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31
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Zhou Y, Endres CJ, Brasić JR, Huang SC, Wong DF. Linear regression with spatial constraint to generate parametric images of ligand-receptor dynamic PET studies with a simplified reference tissue model. Neuroimage 2003; 18:975-89. [PMID: 12725772 DOI: 10.1016/s1053-8119(03)00017-x] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
For the quantitative analysis of ligand-receptor dynamic positron emission tomography (PET) studies, it is often desirable to apply reference tissue methods that eliminate the need for arterial blood sampling. A common technique is to apply a simplified reference tissue model (SRTM). Applications of this method are generally based on an analytical solution of the SRTM equation with parameters estimated by nonlinear regression. In this study, we derive, based on the same assumptions used to derive the SRTM, a new set of operational equations of integral form with parameters directly estimated by conventional weighted linear regression (WLR). In addition, a linear regression with spatial constraint (LRSC) algorithm is developed for parametric imaging to reduce the effects of high noise levels in pixel time activity curves that are typical of PET dynamic data. For comparison, conventional weighted nonlinear regression with the Marquardt algorithm (WNLRM) and nonlinear ridge regression with spatial constraint (NLRRSC) were also implemented using the nonlinear analytical solution of the SRTM equation. In contrast to the other three methods, LRSC reduces the percent root mean square error of the estimated parameters, especially at higher noise levels. For estimation of binding potential (BP), WLR and LRSC show similar variance even at high noise levels, but LRSC yields a smaller bias. Results from human studies demonstrate that LRSC produces high-quality parametric images. The variance of R(1) and k(2) images generated by WLR, WNLRM, and NLRRSC can be decreased 30%-60% by using LRSC. The quality of the BP images generated by WLR and LRSC is visually comparable, and the variance of BP images generated by WNLRM can be reduced 10%-40% by WLR or LRSC. The BP estimates obtained using WLR are 3%-5% lower than those estimated by LRSC. We conclude that the new linear equations yield a reliable, computationally efficient, and robust LRSC algorithm to generate parametric images of ligand-receptor dynamic PET studies.
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Affiliation(s)
- Yun Zhou
- Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
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32
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McLeod M, Pralong D, Copolov D, Dean B. [(3)H]Flumazenil binding in the human hippocampal formation, frontal cortex and cerebellum detected by high-resolution phosphorimaging. Brain Res 2002; 926:27-32. [PMID: 11814403 DOI: 10.1016/s0006-8993(01)03285-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The pharmacological characterisation of the benzodiazepine binding site associated with the gamma-aminobutyric acid (GABA(A)) receptor in human brain has been demonstrated using in situ radioligand binding and autoradiography. The use of high-resolution phosphorimaging has allowed both the affinity (K(d)) and density (B(max)) of [(3)H]flumazenil binding to be measured within regions of the hippocampal formation as well as the cerebellum and frontal cortex. The Scatchard plots of data from all brain regions were linear with Hill coefficients close to unity consistent with the presence of a single binding site for [(3)H]flumazenil. The affinities of [(3)H]flumazenil binding within all the brain regions were similar (K(d) 1.57+/-0.20-3.08+/-0.01 nM), while the density of [(3)H]flumazenil binding varied significantly between the brain regions analysed (B(max) 182.7+/-7.3-596.7+/-34.0 fmol/mg ETE; P<0.0001). In conclusion, the present results indicate that in situ radioligand binding and high-resolution phosphorimaging techniques can be utilized to measure the distribution, density and affinity of [(3)H]flumazenil to the GABA(A) receptor within the human frontal cortex, cerebellum and hippocampal formation.
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Affiliation(s)
- Mark McLeod
- The Rebecca L. Cooper Research Laboratories, The Mental Health Research Institute, Locked Bag 11, Parkville, Victoria, Australia
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33
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Ginovart N, Wilson AA, Meyer JH, Hussey D, Houle S. Positron emission tomography quantification of [(11)C]-DASB binding to the human serotonin transporter: modeling strategies. J Cereb Blood Flow Metab 2001; 21:1342-53. [PMID: 11702049 DOI: 10.1097/00004647-200111000-00010] [Citation(s) in RCA: 170] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
[(11) C]-DASB, namely [(11) C]-3-amino-4-(2-dimethylaminomethyl-phenylsulfanyl)-benzonitrile, is a new highly selective radioligand for the in vivo visualization of the serotonin transporter (SERT) using positron emission tomography (PET). The current study evaluates different kinetic modeling strategies for quantification of [(11)C]-DASB binding in five healthy humans. Kinetic analyses of tissue data were performed with a one-tissue (1CM) and a two-tissue (2CM) compartment model. Time-activity curves were well described by a 1CM for all regions. A 2CM model with four parameters failed to converge reliably. Reliable fits of the data were obtained only if no more than three parameters were allowed to vary. However, even then, the rate constants k(3) and k(4) were estimated with poor precision. Only the ratio k(3)/k(4) was stable. Goodness of fit was not improved by using a 2CM as compared with a 1CM. The minimal study duration required to obtain stable k(3)/k(4) estimates was 80 minutes. For routine use of [(11)C]-DASB, several simplified methods using the cerebellum as a reference region to estimate nonspecific binding were also evaluated. The transient equilibrium, the linear graphical analysis, the ratio of target to reference region, and the simplified reference tissue methods all gave binding potential values consistent with those obtained with the 2CM. The suitability of [(11)C]-DASB for research on the SERT using PET is thus supported by the observations that tissue data can be described using a kinetic analysis and that simplified quantitative methods, using the cerebellum as reference, provide reliable estimates of SERT binding parameters.
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Affiliation(s)
- N Ginovart
- PET Center, Center for Addiction and Mental Health, and University of Toronto, Toronto, Ontario, Canada
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34
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Chugani DC, Muzik O, Juhász C, Janisse JJ, Ager J, Chugani HT. Postnatal maturation of human GABAAreceptors measured with positron emission tomography. Ann Neurol 2001. [DOI: 10.1002/ana.1003] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Hara Y, Kobayashi H, Ooshiro S, Futamura K, Nishino T, Chugun A, Temma K, Kondo H. Negative inotropic effect of diazepam in isolated guinea pig heart. J Vet Med Sci 2001; 63:135-43. [PMID: 11258448 DOI: 10.1292/jvms.63.135] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The inotropic effect of diazepam, a benzodiazepine derivative, and its mechanism of action were examined using guinea pig heart and single ventricular cell preparations. In Langendorff hearts and right ventricular free-wall preparations, diazepam (10 to 100 microM) produced a monophasic negative inotropic effect in a concentration dependent manner. Neither a central type (flumazenil 1 microM) nor a peripheral type (PK11195 10 microM) of benzodiazepine receptor antagonist antagonized the monophasic negative inotropic effects of diazepam. Diazepam (10 to 100 microM) shortened action potential duration of papillary muscle in a concentration dependent manner. In isolated single ventricular cells, diazepam (30 and 100 microM) inhibited the calcium current (I(Ca)) in a concentration dependent manner. Diazepam produced a significant decrease in I(Ca) elicited by first depolarizing pulses, however, the decrease of I(Ca) was not augmented during a train of depolarizing pulses. Thus, diazepam appears to produce a tonic block of cardiac calcium channels and the mode of inhibition is clearly different from the use-dependent block of verapamil. From these results, it was concluded that diazepam produces a monophasic negative inotropic effect that is independent of the benzodiazepine receptor, and is probably mediated through an inhibition of I(Ca) in guinea pig heart preparations.
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Affiliation(s)
- Y Hara
- Department of Veterinary Pharmacology, School of Veterinary Medicine and Animal Sciences, Kitasato University, Aomori, Japan
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36
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Sanabria-Bohórquez SM, Arno P, Sibomana M, Coppens A, Michel C, Veraart C. Decreased benzodiazepine receptor density in the cerebellum of early blind human subjects. Brain Res 2001; 888:203-211. [PMID: 11150476 DOI: 10.1016/s0006-8993(00)03049-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
As a first approach to study the effect of early visual deprivation in the GABA-ergic inhibitory system, the distribution of benzodiazepine receptors (BZR) was accurately estimated using [11C]flumazenil ([11C]FMZ). Measurements were carried out in five subjects who became blind early in life and in five sighted control subjects. The interactions between [11C]FMZ and BZR were described using a non-linear compartmental analysis which permitted to estimate the BZR synaptic density independently of other model parameters. The distribution of BZR in the visual areas and other cortical regions of blind subjects was qualitatively and quantitatively similar to that of controls. However, the BZR density in the cerebellum was significantly lower in blind than in control subjects (P<0.01). Our findings suggest that modifications of the cerebellar neural circuitry may be concomitant to the already observed compensatory reorganization in cerebral areas of blind subjects.
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Affiliation(s)
- S M Sanabria-Bohórquez
- Neural Rehabilitation Engineering Laboratory, GREN-5446, Université Catholique de Louvain, Avenue Hippocrate, 54, B-1200, Brussels, Belgium
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37
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Millet P, Graf C, Buck A, Walder B, Westera G, Broggini C, Arigoni M, Slosman D, Bouras C, Ibáñez V. Similarity and robustness of PET and SPECT binding parameters for benzodiazepine receptors. J Cereb Blood Flow Metab 2000; 20:1587-603. [PMID: 11083234 DOI: 10.1097/00004647-200011000-00009] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The single photon emission computed tomography (SPECT) radiotracer [123I]iomazenil is used to assess benzodiazepine receptor binding parameters. These measurements are relative indices of benzodiazepine receptor concentration (B'max). To evaluate the ability of such indices in accurately accessing the B'max the authors compared them with absolute values of B'max, measured using positron emission tomography (PET). The authors performed SPECT, PET, and magnetic resonance imaging (MRI) studies on a group composed of seven subjects. For SPECT studies, the authors administered a single injection of [123I]iomazenil and estimated the total and specific distribution volumes (DV(T SPECT), DV(S SPECT)) and the binding potential (BP) using unconstrained (BP(SPECT)) and constrained (BP(C SPECT)) compartmental models. For PET studies, the authors used a multiinjection approach with [11C]flumazenil and unlabeled flumazenil to estimate absolute values of receptor concentration, B'max, and some other binding parameters. The authors studied the correlation of different binding parameters with B'max. To study the robustness of the binding parameter measurements at the pixel level, the authors applied a wavelet-based filter to improve signal-to-noise ratio of time-concentration curves, and the calculated kinetic parameters were used to build up parametric images. For PET data, the B'max and the DV(PET) were highly correlated (r = 0.988). This confirms that it is possible to use the DV(PET) to access benzodiazepine receptor density. For SPECT data, the correlation between DV(SPECT) estimated using a two- and three-compartment model was also high (r = 0.999). The DV(T SPECT) and BP(C SPECT) parameters estimated with a constrained three-compartment model or the DV(T''SPECT) parameter estimated with a two-compartment model were also highly correlated to the B'max parameter estimated with PET. Finally, the robustness of the binding parameters allowed the authors to build pixel-by-pixel parametric images using SPECT data.
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Affiliation(s)
- P Millet
- Department of Psychiatry, University Hospital of Geneva, Switzerland
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Mishina M, Senda M, Kimura Y, Toyama H, Ishiwata K, Ohyama M, Nariai T, Ishii K, Oda K, Sasaki T, Kitamura S, Katayama Y. Intrasubject correlation between static scan and distribution volume images for [11C]flumazenil PET. Ann Nucl Med 2000; 14:193-8. [PMID: 10921484 DOI: 10.1007/bf02987859] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Accumulation of [11C]flumazenil (FMZ) reflects central nervous system benzodiazepine receptor (BZR). We searched for the optimal time for a static PET scan with FMZ as semi-quantitative imaging of BZR distribution. In 10 normal subjects, a dynamic series of decay-corrected PET scans was performed for 60 minutes, and the arterial blood was sampled during the scan to measure radioactivity and labeled metabolites. We generated 13 kinds of "static scan" images from the dynamic scan in each subject, and analyzed the pixel correlation for these images versus distribution volume (DV) images. We also analyzed the time for the [11C]FMZ in plasma and tissue to reach the equilibrium. The intra-subject pixel correlation demonstrated that the "static scan" images for the period centering around 30 minutes post-injection had the strongest linear correlation with the DV image. The ratio of radioactivity in the cortex to that in the plasma reached a peak at 40 minutes after injection. Considering the physical decay and patient burden, we conclude that the decay corrected static scan for [11C]FMZ PET as semi-quantitative imaging of BZR distribution is to be optimally acquired from 20 to 40 minutes after injection.
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Affiliation(s)
- M Mishina
- Second Department of Internal Medicine, Nippon Medical School, Japan.
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39
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Bremner JD, Horti A, Staib LH, Zea-Ponce Y, Soufer R, Charney DS, Baldwin R. Kinetic modeling of benzodiazepine receptor binding with PET and high specific activity [(11)C]Iomazenil in healthy human subjects. Synapse 2000; 35:68-77. [PMID: 10579810 DOI: 10.1002/(sici)1098-2396(200001)35:1<68::aid-syn9>3.0.co;2-h] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Quantitation of the PET benzodiazepine receptor antagonist, [(11)C]Iomazenil, using low specific activity radioligand was recently described. The purpose of this study was to quantitate benzodiazepine receptor binding in human subjects using PET and high specific activity [(11)C]Iomazenil. Six healthy human subjects underwent PET imaging following a bolus injection of high specific activity (>100 Ci/mmol) [(11)C]iomazenil. Arterial samples were collected at multiple time points after injection for measurement of unmetabolized total and nonprotein-bound parent compound in plasma. Time activity curves of radioligand concentration in brain and plasma were analyzed using two and three compartment model. Kinetic rate constants of transfer of radioligand between plasma, nonspecifically bound brain tissue, and specifically bound brain tissue compartments were fitted to the model. Values for fitted kinetic rate constants were used in the calculation of measures of benzodiazepine receptor binding, including binding potential (the ratio of receptor density to affinity), and product of BP and the fraction of free nonprotein-bound parent compound (V(3)'). Use of the three compartment model improved the goodness of fit in comparison to the two compartment model. Values for kinetic rate constants and measures of benzodiazepine receptor binding, including BP and V(3)', were similar to results obtained with the SPECT radioligand [(123)I]iomazenil, and a prior report with low specific activity [(11)C]Iomazenil. Kinetic modeling using the three compartment model with PET and high specific activity [(11)C]Iomazenil provides a reliable measure of benzodiazepine receptor binding. Synapse 35:68-77, 2000. Published 2000 Wiley-Liss, Inc.
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Affiliation(s)
- J D Bremner
- Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, Connecticut 06250, USA.
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40
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Smith JS, Zubieta JK, Price JC, Flesher JE, Madar I, Lever JR, Kinter CM, Dannals RF, Frost JJ. Quantification of delta-opioid receptors in human brain with N1'-([11C]methyl) naltrindole and positron emission tomography. J Cereb Blood Flow Metab 1999; 19:956-66. [PMID: 10478647 DOI: 10.1097/00004647-199909000-00003] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The regional binding of N1'-([11C]methyl)naltrindole (MeNTI), a selective delta-opioid antagonist, was studied in healthy human subjects with positron emission tomography (PET). After the bolus intravenous administration of high specific activity [11C]MeNTI, PET was performed over 90 minutes. Arterial plasma samples were obtained during the scanning period and assayed for the presence of radiolabeled metabolites. The data were analyzed with various kinetic (two- and three-compartment models, Patlak graphical analysis) and nonkinetic (apparent volume of distribution and activity at a late scanning time) approaches. This tracer showed irreversible binding characteristics during the scanning period used. The results of the analyses also were compared with the density and distribution of delta-opioid receptors in the human brain in vitro. Additionally, computer simulations were performed to assess the effects of changes in receptor binding and tracer transport changes on the perceived binding parameters obtained with the models. A constrained three-compartment kinetic model was demonstrated to be superior to other quantification models for the description of MeNTI kinetics and quantification of delta receptor binding in the human brain with 11C-labeled MeNTI.
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Affiliation(s)
- J S Smith
- Department of Radiology, Johns Hopkins Medical Institutions, Baltimore, Maryland, USA
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41
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Bremner JD, Baldwin R, Horti A, Staib LH, Ng CK, Tan PZ, Zea-Ponce Y, Zoghbi S, Seibyl JP, Soufer R, Charney DS, Innis RB. Quantitation of benzodiazepine receptor binding with PET [11C]iomazenil and SPECT [123I]iomazenil: preliminary results of a direct comparison in healthy human subjects. Psychiatry Res 1999; 91:79-91. [PMID: 10515463 DOI: 10.1016/s0925-4927(99)00015-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Although positron emission tomography (PET) and single photon emission computed tomography (SPECT) are increasingly used for quantitation of neuroreceptor binding, almost no studies to date have involved a direct comparison of the two. One study found a high level of agreement between the two techniques, although there was a systematic 30% increase in measures of benzodiazepine receptor binding in SPECT compared with PET. The purpose of the current study was to directly compare quantitation of benzodiazepine receptor binding in the same human subjects using PET and SPECT with high specific activity [11C]iomazenil and [123I]iomazenil, respectively. All subjects were administered a single bolus of high specific activity iomazenil labeled with 11C or 123I followed by dynamic PET or SPECT imaging of the brain. Arterial blood samples were obtained for measurement of metabolite-corrected radioligand in plasma. Compartmental modeling was used to fit values for kinetic rate constants of transfer of radioligand between plasma and brain compartments. These values were used for calculation of binding potential (BP = Bmax/Kd) and product of BP and the fraction of free non-protein-bound parent compound (V3'). Mean values for V3' in PET and SPECT were as follows: temporal cortex 23+/-5 and 22+/-3 ml/g, frontal cortex23+/-6 and 22+/-3 ml/g, occipital cortex 28+/-3 and 31+/-5 ml/g, and striatum 4+/-4 and 7+/-4 ml/g. These preliminary findings indicate that PET and SPECT provide comparable results in quantitation of neuroreceptor binding in the human brain.
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Affiliation(s)
- J D Bremner
- Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, CT 06520, USA.
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42
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Ito H, Hietala J, Blomqvist G, Halldin C, Farde L. Comparison of the transient equilibrium and continuous infusion method for quantitative PET analysis of [11C]raclopride binding. J Cereb Blood Flow Metab 1998; 18:941-50. [PMID: 9740097 DOI: 10.1097/00004647-199809000-00003] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Several approaches have been applied for quantification of D2 dopamine receptors in positron emission tomography studies using [11C]raclopride. Initial approaches were based on analyses of data obtained after rapid bolus injection of [11C]raclopride. A continuous infusion paradigm has more recently been applied. The current study compares these approaches in healthy men. Two positron emission tomography measurements were performed in each of six healthy men, the first with rapid bolus injection and the second with continuous infusion of [11C]raclopride. In rapid bolus injection, the binding potential was calculated by the following methods. One approach is the kinetic analysis using the standard three-compartment model. Another is to define a transient equilibrium at the moment when the specific binding reaches its maximum. In continuous infusion, binding potential was calculated by using time-activity data at equilibrium condition. All methods gave almost identical binding potential, representing cross-validation of these methods. The continuous infusion method can provide "true" equilibrium condition. The kinetic analysis is a sophisticated approach but requires determination of an arterial input function. The transient equilibrium method thus is suitable for routine clinical research, since it does not require determination of an arterial input function.
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Affiliation(s)
- H Ito
- Karolinska Institutet, Department of Clinical Neuroscience, Karolinska Hospital, Stockholm, Sweden
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43
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Savic I, Blomqvist G, Halldin C, Litton JE, Gulyas B. Regional increases in [11C]flumazenil binding after epilepsy surgery. Acta Neurol Scand 1998; 97:279-86. [PMID: 9613555 DOI: 10.1111/j.1600-0404.1998.tb05953.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Animal experiments suggest that epileptic seizures alter the expression of mRNA for neuro-receptors. PET measurements with [11C]flumazenil show that patients with partial seizures have a reduced density of benzodiazepine (BZ) receptors in the epileptogenic regions (ER) and some of the target areas for seizure activity, the so called projection areas. Recent data suggest that the degree of BZ receptor reduction in ER is correlated to seizure frequency. We therefore hypothesized that seizure activity can alter the BZ receptor binding, and that some of these changes could normalize when the seizures disappeared. METHODS In 4 patients whose seizures were generated by mesial temporal lobe structures, BZ receptor density was measured with [11C]flumazenil PET before, and 1 year after the epilepsy surgery and cessation of seizures. By use of a computerized anatomical brain atlas the same regions were analyzed in both PET scans, and the results related to data from 7 healthy controls. RESULTS Presurgical PET scans showed reductions in BZ receptor density in the epileptogenic region and some of its primary projection areas. Other cortical regions had normal values. Postsurgically, the calculated BZ receptor density normalized (29+/-17% increase) in several of the affected projection areas, whereas the values in other cortical regions remained unaltered. CONCLUSION Regional reductions in BZ receptor density may be dynamic and related to seizures. The present preliminary observations encourage further studies on seizure-related changes in regional receptor binding in humans.
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Affiliation(s)
- I Savic
- Karolinska Institute, Dept of Neurology, Huddinge Hospital, Sweden
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44
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Gifford AN, Gatley SJ, Volkow ND. Evaluation of the importance of rebinding to receptors in slowing the approach to equilibrium of high-affinity PET and SPECT radiotracers. Synapse 1998; 28:167-75. [PMID: 9450517 DOI: 10.1002/(sici)1098-2396(199802)28:2<167::aid-syn7>3.0.co;2-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The importance of rebinding to receptors in influencing the kinetics of in vivo binding of PET and SPECT radiotracers was evaluated by examining the binding of a high-affinity D1 receptor radiotracer, [3H]SCH 23390, in tissue homogenates, living brain slices, and in vivo. In rat striatal homogenates, [3H]SCH 23390 binding reached equilibrium with a half-time of 6 min. By contrast, in striatal brain slices incubated in [3H] SCH 23390, the radioactivity levels in the slice increased in a linear fashion over the 4-h incubation, with no indication of an approach to equilibrium at the termination of the experiment. In in vivo experiments, [3H]SCH 23390 was given as a slow intravenous infusion to mice, using a paradigm that kept the plasma concentration at a constant level. Under these conditions, striatal [3H] SCH 23390 levels increased in a linear fashion over the 4-h infusion period, similar to what was observed in the brain slices, and as in the slices there was no indication of approach to a steady state. However, when given instead as a single-bolus intravenous dose, the striatal [3H]SCH 23390 levels reached a peak only 15 min after injection. Calculations based on the slice experiments, in which the blood-brain barrier is absent, suggested that the rate-limiting step accounting for the failure of [3H]SCH 23390 levels to reach equilibrium was its hindered diffusion as a result of repeated rebinding to receptors. This phenomenon may also be important in vivo and should be considered as a factor in determining the time-course of binding of radiotracers in PET and SPECT experiments where either the receptor density or radiotracer affinity is high.
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Affiliation(s)
- A N Gifford
- Medical Department, Brookhaven National Laboratory, Upton, New York 11973, USA
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45
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A612 DOSE-DEPENDENT EFFECTS OF ISOFLURANE ON GABA sub A -RECEPTOR CONFORMATION IN VIVO IN HUMANS. Anesthesiology 1997. [DOI: 10.1097/00000542-199709001-00612] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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46
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Ito H, Kawashima R, Koyama M, Goto R, Sato K, Ono S, Fukuda H. A method for the quantification of benzodiazepine receptors by using 123I-iomazenil and SPECT with one scan and one blood sampling. Ann Nucl Med 1997; 11:101-8. [PMID: 9212889 DOI: 10.1007/bf03164817] [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: 02/04/2023]
Abstract
Iodine-123-iomazenil (Iomazenil) is a ligand of central type benzodiazepine receptors for single photon emission computed tomography (SPECT). Previously we reported a simple, table look-up method for quantification of its binding potential (BP) by using two SPECT scans and calibrated standard input function with one blood sampling. This method is based on a two-compartment model (K1: influx rate constant; k2: efflux rate constant; Vd (= K1/k2): the total distribution volume corresponding BP), and requires two SPECT scans for calculating both K1 and Vd values. If the K1 value in the two-compartment model can be assumed to be constant, the radioactivity of one SPECT scan at 180 min after injection can be considered to tabulate as a function of Vd for a given K1 value and a given input function, and a table look-up procedure provides the corresponding Vd value. The purpose of this study was to develop a simple, autoradiographic method for quantification of BP by using one SPECT scan and calibrated standard input function with one blood sampling. SPECT studies were performed on 14 patients. A dynamic SPECT scan was initiated following an intravenous bolus injection of Iomazenil. A static SPECT scan was performed at 180 min after the injection. Frequent blood sampling from the brachial artery was performed on all subjects to determine the arterial input function. Simulation studies revealed that errors in calculated Vd values were around +/-10-15% for varied K1 values. A good correlation was observed between total distribution volume values calculated by three-compartment model analysis and those calculated by the present method (r = 0.90), supporting the validity of this method. The present method is simple and applicable for clinical use, and will be able to provide images of BP.
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Affiliation(s)
- H Ito
- Department of Nuclear Medicine and Radiology, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan
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47
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Delforge J, Spelle L, Bendriem B, Samson Y, Syrota A. Parametric images of benzodiazepine receptor concentration using a partial-saturation injection. J Cereb Blood Flow Metab 1997; 17:343-55. [PMID: 9119907 DOI: 10.1097/00004647-199703000-00011] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The in vivo quantification of the benzodiazepine receptor concentration in human brain using positron emission tomography (PET) and 11C-flumazenil (11C-FMZ), is usually based on a three-compartment model and on PET curves measured in a small number of large regions of interest; however, it should be interesting to estimate the receptor concentration for each pixel and to build quantified images of the receptor concentration. The main advantage is to allow screening of the receptor site localization and visual observation of the possible abnormalities. Up to now, all the methods described include complex experimental protocols, difficult to use in routine examinations. In this paper, we propose the partial-saturation approach to obtain parametric images of benzodiazepine receptor concentration and FMZ affinity. It consists of a single FMZ injection with a low specific activity, followed by Scatchard analysis. Like other parametric imaging methods, this partial-saturation approach can lead to a small percentage (< 1%) of unrealistic values in receptor-poor regions; however, it is the only method that allows receptor concentration and affinity images to be obtained from a single-injection 40-min experiment without blood sampling. We also propose a second method in which the receptor concentration map is directly deduced from the PET image acquired 5 to 10 min after a partial-saturation injection. This method assumes a known and constant FMZ affinity value but requires only very simple corrections of this PET image. It is robust (negative values are never found) and quite simple to use in routine examination of patients (no blood sampling, single injection, only 10-min experiment).
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Affiliation(s)
- J Delforge
- Commissariat à l'Energie Atomique, Service Hospitalier F. Joliot, Orsay, France
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48
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Pauli S, Sedvall G. Three-dimensional visualization and quantification of the benzodiazepine receptor population within a living human brain using PET and MRI. Eur Arch Psychiatry Clin Neurosci 1997; 247:61-70. [PMID: 9177951 DOI: 10.1007/bf02900195] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Positron emission tomography (PET) in combination with receptor-selective high-affinity radioligands allows the characterization of neuroreceptor distributions in the living human brain. Thus far, the visualization and quantification of receptors with PET have been limited to series of two-dimensional (2D) image planes of the anatomic receptor distribution. The development of high-resolution PET has increased the number of planes to approximately 50, supplying an excessive amount of image information from a single experiment. The inherent limitations of 2D techniques make them insufficient to apprehend and efficiently analyze this cumbersome amount of data. In the present communication we describe procedures to visualize and quantify in three dimensions (3D) the total image information from the compound set of 47 2D planes of a PET experiment using commercially available software. Three-dimensional computer graphic and volume rendering techniques were used to analyze and display the results. For the experimental application the benzodiazepine (BZ) antagonist [11C]flumazenil was used as radioligand to visualize the BZ receptor (BZR) population in the brain of a healthy human subject. Three-dimensional images of the radioligand binding receptor population were displayed with regard to volume and form in relation to the corresponding anatomic structures in the brain reconstructed from MR images. The volume-rendering technique allowed the inspection of PET signals representing BZR populations in the interior of the hemisphere as viewed from the medial projection. Thresholding and seeding techniques were used to define volumes and quantities. Using the PET data and volume rendering, the total amount of cerebral BZRs (NCerebrum) and the apparent volume they take into account (V(BZR, Cerebrum)app) could he calculated for the first time using an automated procedure. The cerebrum of the healthy subject contained 17.6 nmol of BZRs in a volume of approximately 1.25 L. The principles and application of the technical development described offer new dimensions to clinical neuroscience and should be practically useful for automated quantitative determination of neuroreceptor number in brain regions of patients with neuropsychiatric disorders and in relation to drug treatment.
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Affiliation(s)
- S Pauli
- Department of Clinical Neuroscience, Karolinska Institute and Hospital, Stockholm, Sweden.
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49
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Millet P, Delforge J, Pappata S, Syrota A, Cinotti L. Error analysis on parameter estimates in the ligand-receptor model: application to parameter imaging using PET data. Phys Med Biol 1996; 41:2739-56. [PMID: 8971966 DOI: 10.1088/0031-9155/41/12/012] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Positron emission tomography and compartmental models allow the in vivo analysis of radioligand binding to receptor sites in the human brain. Benzodiazepine receptor binding was studied using a three-compartmental model and [11C]flumazenil. Four and five parameters were estimated from a single kinetic curve obtained with a multi-injection protocol, and parametric maps of receptor density and of the individual kinetic parameters were created with four-pixel sampling of the experimental images. The coefficient of variation on each estimated model parameter was calculated using the diagonal elements of the covariance matrix. However, these estimates are valid only under some statistical hypotheses which are not always verified with PET data. Thus, in order to verify the validity of the coefficient of variation of each parameter calculated with the covariance matrix, these results have been compared with the more rigorous statistical results provided by a Monte Carlo simulation. The study showed a negligible difference between the results obtained by the two methods for a low noise level in time-concentration curves encountered using large ROIs. However, this bias becomes less negligible when the noise level is high and some estimations of the coefficients of variation were unacceptable (> 100%) with the five-parameter model. Such difficulties did not occur with the four-parameter model which led to parametric images with good quality and acceptable estimates of coefficients of variation (less than 20% in about 75% of the ROIs).
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Affiliation(s)
- P Millet
- CEA, Service Hospitalier Frédéric Joliot, Commissariat à l'Energie Atomique, Orsay, France
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50
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Ito H, Goto R, Koyama M, Kawashima R, Ono S, Sato K, Fukuda H. A simple method for the quantification of benzodiazepine receptors using iodine-123 iomazenil and single-photon emission tomography. EUROPEAN JOURNAL OF NUCLEAR MEDICINE 1996; 23:782-91. [PMID: 8662117 DOI: 10.1007/bf00843707] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Iodine-123 iomazenil (Iomazenil) is a ligand for central type benzodiazepine receptors that is suitable for single-photon emission tomography (SPET). The purpose of this study was to develop a simple method for the quantification of its binding potential (BP). The method is based on a two-compartment model (K1, influx rate constant; k2', efflux rate constant; VT' (=K1/k2'), the total distribution volumes relative to the total arterial tracer concentration), and requires two SPET scans and one blood sampling. For a given input function, the radioactivity ratio of the early to delayed scans can be considered to tabulate as a function of k2', and a table look-up procedure provides the corresponding k2' value, from which K1 and VT' values are then calculated. The arterial input function is obtained by calibration of the standard input function by the single blood sampling. SPET studies were performed on 14 patients with cerebrovascular diseases, dementia or brain tumours (mean age+/-SD, 56.0+/-12.2). None of the patients had any heart, renal or liver disease. A dynamic SPET scan was performed following intravenous bolus injection of Iomazenil. A static SPET scan was performed at 180 min after injection. Frequent blood sampling from the brachial artery was performed on all subjects for determination of the arterial input function. Two-compartment model analysis was validated for calculation of the VT' value of Iomazenil. Good correlations were observed between VT' values calculated by three-compartment model analysis and those calculated by the present method, in which the scan time combinations (early scan/delayed scan) used were 15/180 min, 30/180 min or 45/180 min (all combinations: r=0.92), supporting the validity of this method. The present method is simple and applicable for clinical use.
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Affiliation(s)
- H Ito
- Department of Nuclear Medicine and Radiology, Division of Brain Sciences, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan
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