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Vezzani A, Ravizza T, Bedner P, Aronica E, Steinhäuser C, Boison D. Astrocytes in the initiation and progression of epilepsy. Nat Rev Neurol 2022; 18:707-722. [PMID: 36280704 PMCID: PMC10368155 DOI: 10.1038/s41582-022-00727-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/16/2022] [Indexed: 11/09/2022]
Abstract
Epilepsy affects ~65 million people worldwide. First-line treatment options include >20 antiseizure medications, but seizure control is not achieved in approximately one-third of patients. Antiseizure medications act primarily on neurons and can provide symptomatic control of seizures, but do not alter the onset and progression of epilepsy and can cause serious adverse effects. Therefore, medications with new cellular and molecular targets and mechanisms of action are needed. Accumulating evidence indicates that astrocytes are crucial to the pathophysiological mechanisms of epilepsy, raising the possibility that these cells could be novel therapeutic targets. In this Review, we discuss how dysregulation of key astrocyte functions - gliotransmission, cell metabolism and immune function - contribute to the development and progression of hyperexcitability in epilepsy. We consider strategies to mitigate astrocyte dysfunction in each of these areas, and provide an overview of how astrocyte activation states can be monitored in vivo not only to assess their contribution to disease but also to identify markers of disease processes and treatment effects. Improved understanding of the roles of astrocytes in epilepsy has the potential to lead to novel therapies to prevent the initiation and progression of epilepsy.
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Affiliation(s)
- Annamaria Vezzani
- Department of Neuroscience, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Milano, Italy.
| | - Teresa Ravizza
- Department of Neuroscience, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Milano, Italy
| | - Peter Bedner
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Eleonora Aronica
- Amsterdam UMC, University of Amsterdam, Department of (Neuro)Pathology, Amsterdam Neuroscience, Amsterdam, Netherlands
- Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, Netherlands
| | - Christian Steinhäuser
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Detlev Boison
- Department of Neurosurgery, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ, USA
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2
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Berlowitz I, Egger K, Cumming P. Monoamine Oxidase Inhibition by Plant-Derived β-Carbolines; Implications for the Psychopharmacology of Tobacco and Ayahuasca. Front Pharmacol 2022; 13:886408. [PMID: 35600851 PMCID: PMC9121195 DOI: 10.3389/fphar.2022.886408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 04/07/2022] [Indexed: 11/13/2022] Open
Abstract
The monoamine oxidases (MAOs) are flavin-containing amine oxidoreductases responsible for metabolism of many biogenic amine molecules in the brain and peripheral tissues. Whereas serotonin is the preferred substrate of MAO-A, phenylethylamine is metabolized by MAO-B, and dopamine and tyramine are nearly ambivalent with respect to the two isozymes. β-Carboline alkaloids such as harmine, harman(e), and norharman(e) are MAO inhibitors present in many plant materials, including foodstuffs, medicinal plants, and intoxicants, notably in tobacco (Nicotiana spp.) and in Banisteriopsis caapi, a vine used in the Amazonian ayahuasca brew. The β-carbolines present in B. caapi may have effects on neurogenesis and intrinsic antidepressant properties, in addition to potentiating the bioavailability of the hallucinogen N,N-dimethyltryptamine (DMT), which is often present in admixture plants of ayahuasca such as Psychotria viridis. Tobacco also contains physiologically relevant concentrations of β-carbolines, which potentially contribute to its psychopharmacology. However, in both cases, the threshold of MAO inhibition sufficient to interact with biogenic amine neurotransmission remains to be established. An important class of antidepressant medications provoke a complete and irreversible inhibition of MAO-A/B, and such complete inhibition is almost unattainable with reversible and competitive inhibitors such as β-carbolines. However, the preclinical and clinical observations with synthetic MAO inhibitors present a background for obtaining a better understanding of the polypharmacologies of tobacco and ayahuasca. Furthermore, MAO inhibitors of diverse structures are present in a wide variety of medicinal plants, but their pharmacological relevance in many instances remains to be established.
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Affiliation(s)
- Ilana Berlowitz
- Department of Nuclear Medicine, Inselspital Bern University Hospital, University of Bern, Bern, Switzerland
- *Correspondence: Ilana Berlowitz,
| | - Klemens Egger
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Paul Cumming
- Department of Nuclear Medicine, Inselspital Bern University Hospital, University of Bern, Bern, Switzerland
- School of Psychology and Counselling, Queensland University of Technology, Brisbane, QLD, Australia
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3
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Chen Z, Haider A, Chen J, Xiao Z, Gobbi L, Honer M, Grether U, Arnold SE, Josephson L, Liang SH. The Repertoire of Small-Molecule PET Probes for Neuroinflammation Imaging: Challenges and Opportunities beyond TSPO. J Med Chem 2021; 64:17656-17689. [PMID: 34905377 PMCID: PMC9094091 DOI: 10.1021/acs.jmedchem.1c01571] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Neuroinflammation is an adaptive response of the central nervous system to diverse potentially injurious stimuli, which is closely associated with neurodegeneration and typically characterized by activation of microglia and astrocytes. As a noninvasive and translational molecular imaging tool, positron emission tomography (PET) could provide a better understanding of neuroinflammation and its role in neurodegenerative diseases. Ligands to translator protein (TSPO), a putative marker of neuroinflammation, have been the most commonly studied in this context, but they suffer from serious limitations. Herein we present a repertoire of different structural chemotypes and novel PET ligand design for classical and emerging neuroinflammatory targets beyond TSPO. We believe that this Perspective will support multidisciplinary collaborations in academic and industrial institutions working on neuroinflammation and facilitate the progress of neuroinflammation PET probe development for clinical use.
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Affiliation(s)
- Zhen Chen
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, United States
| | - Ahmed Haider
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, United States
| | - Jiahui Chen
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, United States
| | - Zhiwei Xiao
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, United States
| | - Luca Gobbi
- Pharma Research and Early Development, F. Hoffmann-La Roche Ltd, CH-4070 Basel, Switzerland
| | - Michael Honer
- Pharma Research and Early Development, F. Hoffmann-La Roche Ltd, CH-4070 Basel, Switzerland
| | - Uwe Grether
- Pharma Research and Early Development, F. Hoffmann-La Roche Ltd, CH-4070 Basel, Switzerland
| | - Steven E. Arnold
- Department of Neurology and the Massachusetts Alzheimer’s Disease Research Center, Massachusetts General Hospital, Harvard Medical School, 114 16th Street, Charlestown, Massachusetts 02129, USA
| | - Lee Josephson
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, United States
| | - Steven H. Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, United States
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Kinetic isotope effects and synthetic strategies for deuterated carbon-11 and fluorine-18 labelled PET radiopharmaceuticals. Nucl Med Biol 2021; 96-97:112-147. [PMID: 33892374 DOI: 10.1016/j.nucmedbio.2021.03.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 03/19/2021] [Accepted: 03/30/2021] [Indexed: 11/22/2022]
Abstract
The deuterium labelling of pharmaceuticals is a useful strategy for altering pharmacokinetic properties, particularly for improving metabolic resistance. The pharmacological effects of such metabolites are often assumed to be negligible during standard drug discovery and are factored in later at the clinical phases of development, where the risks and benefits of the treatment and side-effects can be wholly assessed. This paradigm does not translate to the discovery of radiopharmaceuticals, however, as the confounding effects of radiometabolites can inevitably show in preliminary positron emission tomography (PET) scans and thus complicate interpretation. Consequently, the formation of radiometabolites is crucial to take into consideration, compared to non-radioactive metabolites, and the application of deuterium labelling is a particularly attractive approach to minimise radiometabolite formation. Herein, we provide a comprehensive overview of the deuterated carbon-11 and fluorine-18 radiopharmaceuticals employed in PET imaging experiments. Specifically, we explore six categories of deuterated radiopharmaceuticals used to investigate the activities of monoamine oxygenase (MAO), choline, translocator protein (TSPO), vesicular monoamine transporter 2 (VMAT2), neurotransmission and the diagnosis of Alzheimer's disease; from which we derive four prominent deuteration strategies giving rise to a kinetic isotope effect (KIE) for reducing the rate of metabolism. Synthetic approaches for over thirty of these deuterated radiopharmaceuticals are discussed from the perspective of deuterium and radioisotope incorporation, alongside an evaluation of the deuterium labelling and radiolabelling efficacies across these independent studies. Clinical and manufacturing implications are also discussed to provide a more comprehensive overview of how deuterated radiopharmaceuticals may be introduced to routine practice.
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5
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Neuroinflammatory pathways as treatment targets and biomarkers in epilepsy. Nat Rev Neurol 2019; 15:459-472. [DOI: 10.1038/s41582-019-0217-x] [Citation(s) in RCA: 289] [Impact Index Per Article: 57.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/10/2019] [Indexed: 02/06/2023]
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Ravizza T, Vezzani A. Pharmacological targeting of brain inflammation in epilepsy: Therapeutic perspectives from experimental and clinical studies. Epilepsia Open 2018; 3:133-142. [PMID: 30564772 PMCID: PMC6293065 DOI: 10.1002/epi4.12242] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/02/2018] [Indexed: 12/16/2022] Open
Abstract
Increasing evidence supports a pathogenic role of unabated neuroinflammation in various central nervous system (CNS) diseases, including epilepsy. Neuroinflammation is not a bystander phenomenon of the diseased brain tissue, but it may contribute to neuronal hyperexcitability underlying seizure generation, cell loss, and neurologic comorbidities. Several molecules, which constitute the inflammatory milieu in the epileptogenic area, activate signaling pathways in neurons and glia resulting in pathologic modifications of cell function, which ultimately lead to alterations in synaptic transmission and plasticity. Herein we report the up-to-date experimental and clinical evidence that supports the neuromodulatory role of inflammatory mediators, their related signaling pathways, and involvement in epilepsy. We discuss how these mechanisms can be harnessed to discover and validate targets for novel therapeutics, which may prevent or control pharmacoresistant epilepsies.
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Affiliation(s)
- Teresa Ravizza
- Department of NeuroscienceIRCCS – Mario Negri Institute for Pharmacological ResearchMilanoItaly
| | - Annamaria Vezzani
- Department of NeuroscienceIRCCS – Mario Negri Institute for Pharmacological ResearchMilanoItaly
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Astroglial Responses to Amyloid-Beta Progression in a Mouse Model of Alzheimer’s Disease. Mol Imaging Biol 2018; 20:605-614. [DOI: 10.1007/s11307-017-1153-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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8
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Tong J, Rathitharan G, Meyer JH, Furukawa Y, Ang LC, Boileau I, Guttman M, Hornykiewicz O, Kish SJ. Brain monoamine oxidase B and A in human parkinsonian dopamine deficiency disorders. Brain 2017; 140:2460-2474. [PMID: 29050386 DOI: 10.1093/brain/awx172] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 05/30/2017] [Indexed: 11/13/2022] Open
Abstract
See Jellinger (doi:10.1093/awx190) for a scientific commentary on this article. The enzyme monoamine oxidases (B and A subtypes, encoded by MAOB and MAOA, respectively) are drug targets in the treatment of Parkinson's disease. Inhibitors of MAOB are used clinically in Parkinson's disease for symptomatic purposes whereas the potential disease-modifying effect of monoamine oxidase inhibitors is debated. As astroglial cells express high levels of MAOB, the enzyme has been proposed as a brain imaging marker of astrogliosis, a cellular process possibly involved in Parkinson's disease pathogenesis as elevation of MAOB in astrocytes might be harmful. Since brain monoamine oxidase status in Parkinson's disease is uncertain, our objective was to measure, by quantitative immunoblotting in autopsied brain homogenates, protein levels of both monoamine oxidases in three different degenerative parkinsonian disorders: Parkinson's disease (n = 11), multiple system atrophy (n = 11), and progressive supranuclear palsy (n = 16) and in matched controls (n = 16). We hypothesized that if MAOB is 'substantially' localized to astroglial cells, MAOB levels should be generally associated with standard astroglial protein measures (e.g. glial fibrillary acidic protein). MAOB levels were increased in degenerating putamen (+83%) and substantia nigra (+10%, non-significant) in multiple system atrophy; in caudate (+26%), putamen (+27%), frontal cortex (+31%) and substantia nigra (+23%) of progressive supranuclear palsy; and in frontal cortex (+33%), but not in substantia nigra of Parkinson's disease, a region we previously reported no increase in astrocyte protein markers. Although the magnitude of MAOB increase was less than those of standard astrocytic markers, significant positive correlations were observed amongst the astrocyte proteins and MAOB. Despite suggestions that MAOA (versus MAOB) is primarily responsible for metabolism of dopamine in dopamine neurons, there was no loss of the enzyme in the parkinsonian substantia nigra; instead, increased nigral levels of a MAOA fragment and 'turnover' of the enzyme were observed in the conditions. Our findings provide support that MAOB might serve as a biochemical imaging marker, albeit not entirely specific, for astrocyte activation in human brain. The observation that MAOB protein concentration is generally increased in degenerating brain areas in multiple system atrophy (especially putamen) and in progressive supranuclear palsy, but not in the nigra in Parkinson's disease, also distinguishes astrocyte behaviour in Parkinson's disease from that in the two 'Parkinson-plus' conditions. The question remains whether suppression of either MAOB in astrocytes or MAOA in dopamine neurons might influence progression of the parkinsonian disorders.
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Affiliation(s)
- Junchao Tong
- Preclinical Imaging Unit, Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada.,Human Brain Laboratory, Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - Gausiha Rathitharan
- Human Brain Laboratory, Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - Jeffrey H Meyer
- Research Imaging Centre and Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - Yoshiaki Furukawa
- Department of Neurology, Juntendo Tokyo Koto Geriatric Medical Center, and Faculty of Medicine, University and Post Graduate University of Juntendo, Tokyo, Japan
| | - Lee-Cyn Ang
- Division of Neuropathology, London Health Science Centre, University of Western Ontario, London, Ontario, Canada
| | - Isabelle Boileau
- Addiction Imaging Research Group, Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - Mark Guttman
- Centre for Movement Disorders, Markham, Ontario, Canada
| | - Oleh Hornykiewicz
- Centre for Brain Research, Medical University of Vienna, Spitalgasse 4, A-1090 Vienna, Austria
| | - Stephen J Kish
- Human Brain Laboratory, Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
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9
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Koepp MJ, Årstad E, Bankstahl JP, Dedeurwaerdere S, Friedman A, Potschka H, Ravizza T, Theodore WH, Baram TZ. Neuroinflammation imaging markers for epileptogenesis. Epilepsia 2017; 58 Suppl 3:11-19. [PMID: 28675560 DOI: 10.1111/epi.13778] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/06/2017] [Indexed: 12/23/2022]
Abstract
Epilepsy can be a devastating disorder. In addition to debilitating seizures, epilepsy can cause cognitive and emotional problems with reduced quality of life. Therefore, the major aim is to prevent the disorder in the first place: identify, detect, and reverse the processes responsible for its onset, and monitor and treat its progression. Epilepsy often occurs following a latent period of months to years (epileptogenesis) as a consequence of a brain insult, such as head trauma, stroke, or status epilepticus. Although this latent period clearly represents a therapeutic window, we are not able to stratify patients at risk for long-term epilepsy, which is prerequisite for preventative clinical trials. Moreover, because of the length of the latent period, an early biomarker for treatment response would be of high value. Finally, mechanistic biomarkers of epileptogenesis may provide more profound insight in the process of disease development.
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Affiliation(s)
- Matthias J Koepp
- Institute of Neurology, University College London, London, United Kingdom
| | - Eric Årstad
- Department of Chemistry and Institute of Nuclear Medicine, University College London, London, United Kingdom
| | - Jens P Bankstahl
- Department of Nuclear Medicine, Hannover Medical School, Hannover, Germany
| | | | - Alon Friedman
- Ben-Gurion University of the Negev, Beer-Sheva, Israel.,Dalhousie University, Halifax, Nova Scotia, Canada
| | - Heidrun Potschka
- Institute of Pharmacology, Toxicology, and Pharmacy, Ludwig-Maximilians-University, Munich, Germany
| | - Teresa Ravizza
- Department of Neuroscience, IRCCS-Institute for Pharmacological Research Mario Negri, Milan, Italy
| | | | - Tallie Z Baram
- Departments of Pediatrics, Anatomy/Neurobiology, Neurology, University of California-Irvine, Irvine, California, U.S.A
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10
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Arakawa R, Stenkrona P, Takano A, Nag S, Maior RS, Halldin C. Test-retest reproducibility of [ 11C]-L-deprenyl-D 2 binding to MAO-B in the human brain. EJNMMI Res 2017. [PMID: 28634836 PMCID: PMC5478550 DOI: 10.1186/s13550-017-0301-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Background [11C]-l-deprenyl-D2 is a positron emission tomography (PET) radioligand for measurement of the monoamine oxidase B (MAO-B) activity in vivo brain. The estimation of the test-retest reproducibility is important for accurate interpretation of PET studies. Results We performed two [11C]-l-deprenyl-D2 scans for six healthy subjects and evaluated the test-retest variability of this radioligand. MAO-B binding was quantified by two tissue compartment model (2TCM) with three rate constants (K1, k2, k3) using metabolite-corrected plasma radioactivity. The λk3 defined as (K1/k2) × k3 was also calculated. The correlation between MAO-B binding and age, and the effect of partial volume effect correction (PVEc) for the reproducibility were also estimated. %difference of k3 was 2.6% (medial frontal cortex) to 10.3% (hippocampus), and that of λk3 was 5.0% (thalamus) to 9.2% (cerebellum). Mean %difference of all regions were 5.3 and 7.0% in k3 and λk3, respectively. All regions showed below 10% variabilities except the hippocampus in k3 (10.3%). Intraclass correlation coefficient (ICC) of k3 was 0.78 (hippocampus) to 0.98 (medial frontal cortex), and that of λk3 was 0.78 (hippocampus) to 0.95 (thalamus). Mean ICC were 0.94 and 0.89 in k3 and λk3, respectively. The highest positive correlation with age was observed in the hippocampus, as r = 0.75 in k3 and 0.76 in λk3. After PVEc, mean %difference were 5.6 and 7.2% in k3 and λk3, respectively. Mean ICC were 0.92 and 0.90 for k3 and λk3, respectively. These values were almost the same as those before PVEc. Conclusions The present results indicate that k3 and λk3 of [11C]-l-deprenyl-D2 are reliable parameters for test-retest reproducibility with healthy subjects both before and after PVEc. The studies with patients of larger sample size are required for further clinical applications.
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Affiliation(s)
- Ryosuke Arakawa
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden.
| | - Per Stenkrona
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden
| | - Akihiro Takano
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden
| | - Sangram Nag
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden
| | - Rafael S Maior
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden.,Primate Center and Laboratory of Neurosciences and Behavior, Department of Physiological Sciences, Institute of Biology, University of Brasilia, Brasilia, Brazil
| | - Christer Halldin
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden
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Vezzani A, Pascente R, Ravizza T. Biomarkers of Epileptogenesis: The Focus on Glia and Cognitive Dysfunctions. Neurochem Res 2017; 42:2089-2098. [PMID: 28434163 DOI: 10.1007/s11064-017-2271-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 04/12/2017] [Accepted: 04/17/2017] [Indexed: 12/31/2022]
Abstract
The need to find measures that reliably predict the onset of epilepsy after injurious events or how the patient will respond to anti-seizure drugs led to intensive pre-clinical and clinical research to discover non-invasive biomarkers that could increase the sensitivity of existing clinical indicators. The use of experimental models of epileptogenesis and of drug-resistance is instrumental to select the most promising approaches to explore such biomarkers in the pre-clinical setting for further clinical validation. The approaches most frequently used to find clinically useful biomarkers of epileptogenesis include molecular brain imaging, EEG signal analysis and the measure of soluble molecules in biofluids which may reflect brain intrinsic events involved in epilepsy development. Among those, we focused our attention on proton magnetic resonance imaging (1H-MRS)-based analysis of astrocytic activation, and related blood biomarkers, since this cell population appears to be pivotally involved in various epileptogenesis processes triggered by differing insults. Moreover, we also investigated behavioral biomarkers by focusing on cognitive dysfunctions since this deficit represents a typical co-morbidity in epilepsy which may manifest even before the onset of spontaneous seizures. In this review article, we will report our recently published evidence supporting the utility of measuring astrocyte activation, the soluble molecules they release, and the associated cognitive deficits during epileptogenesis for early stratification of animals developing epilepsy. We will discuss the potential clinical translation of our findings for enriching the patient population in preventive clinical trials designed to study anti-epileptogenic treatments.
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Affiliation(s)
- Annamaria Vezzani
- Department of Neuroscience, IRCCS-Istituto Di Ricerche Farmacologiche Mario Negri, Via G. La Masa, 19, 20156, Milan, Italy.
| | - Rosaria Pascente
- Department of Neuroscience, IRCCS-Istituto Di Ricerche Farmacologiche Mario Negri, Via G. La Masa, 19, 20156, Milan, Italy
| | - Teresa Ravizza
- Department of Neuroscience, IRCCS-Istituto Di Ricerche Farmacologiche Mario Negri, Via G. La Masa, 19, 20156, Milan, Italy
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12
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Garden GA, Campbell BM. Glial biomarkers in human central nervous system disease. Glia 2016; 64:1755-71. [PMID: 27228454 PMCID: PMC5575821 DOI: 10.1002/glia.22998] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 04/07/2016] [Accepted: 04/13/2016] [Indexed: 12/13/2022]
Abstract
There is a growing understanding that aberrant GLIA function is an underlying factor in psychiatric and neurological disorders. As drug discovery efforts begin to focus on glia-related targets, a key gap in knowledge includes the availability of validated biomarkers to help determine which patients suffer from dysfunction of glial cells or who may best respond by targeting glia-related drug mechanisms. Biomarkers are biological variables with a significant relationship to parameters of disease states and can be used as surrogate markers of disease pathology, progression, and/or responses to drug treatment. For example, imaging studies of the CNS enable localization and characterization of anatomical lesions without the need to isolate tissue for biopsy. Many biomarkers of disease pathology in the CNS involve assays of glial cell function and/or response to injury. Each major glia subtype (oligodendroglia, astroglia and microglia) are connected to a number of important and useful biomarkers. Here, we describe current and emerging glial based biomarker approaches for acute CNS injury and the major categories of chronic nervous system dysfunction including neurodegenerative, neuropsychiatric, neoplastic, and autoimmune disorders of the CNS. These descriptions are highlighted in the context of how biomarkers are employed to better understand the role of glia in human CNS disease and in the development of novel therapeutic treatments. GLIA 2016;64:1755-1771.
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Affiliation(s)
- Gwenn A. Garden
- Department of Neurology, University of Washington, Seattle, Washington
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13
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Bañuelos-Cabrera I, Cuéllar-Herrera M, Velasco AL, Velasco F, Alonso-Vanegas M, Carmona F, Guevara R, Arias-Montaño JA, Rocha L. Pharmacoresistant temporal lobe epilepsy modifies histamine turnover and H3receptor function in the human hippocampus and temporal neocortex. Epilepsia 2016; 57:e76-80. [DOI: 10.1111/epi.13329] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/08/2016] [Indexed: 11/29/2022]
Affiliation(s)
- Ivette Bañuelos-Cabrera
- Departamentos de Farmacobiología y; Centro de Investigación y de Estudios Avanzados; Department of Pharmacobiology; Mexico City Mexico
| | | | | | | | - Mario Alonso-Vanegas
- National Institute of Neurology and Neurosurgery; “Manuel Velasco Súrez”; Mexico City Mexico
| | - Francia Carmona
- Departamentos de Farmacobiología y; Centro de Investigación y de Estudios Avanzados; Department of Pharmacobiology; Mexico City Mexico
| | - Rosalinda Guevara
- Department of Physiology; School of Medicine; National Autonomous University of Mexico; Mexico City Mexico
| | - José-Antonio Arias-Montaño
- Physiology; Biophysics and Neuroscience; Center of Research and Advanced Studies; Mexico City Mexico
- del Centro de Investigación y de Estudios Avanzados; México DF México
| | - Luisa Rocha
- Departamentos de Farmacobiología y; Centro de Investigación y de Estudios Avanzados; Department of Pharmacobiology; Mexico City Mexico
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14
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Matthews PM, Datta G. Positron-emission tomography molecular imaging of glia and myelin in drug discovery for multiple sclerosis. Expert Opin Drug Discov 2015; 10:557-70. [PMID: 25843125 DOI: 10.1517/17460441.2015.1032240] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Therapies acting on glial cells are being explored for new drug development for multiple sclerosis. Molecular imaging using positron-emission tomography (PET) could address relevant questions in early phase clinical trials. AREAS COVERED In this article, the authors critically review human PET methods that can be applied in specialised centres for imaging activated microglia and astrocytes and myelin. EXPERT OPINION Strengths of PET lie in the molecular selectivity, sensitivity and potential for absolute quantitation. Even now, translocator protein PET radioligands could be used in exploratory studies for interventions targeting brain microglial activation. The clinical and neuropathological meaningfulness of signal from PET radioligands reporting on astrocyte activation through cellular expression of either monoamine oxidase B or the I2-imidazoline receptor or metabolism of [(11)C]acetate can now explored. [(11)C] N-methyl-4,4'-diaminostilbene, a PET marker for myelin, could soon enter first human trials. However, use of any of these PET glial markers demands a well-focused hypothesis and a commitment to validation in the context of use. Enhanced access to these radioligands, standardisation of analyses and lowering the costs of using them are needed if their full promise is to be realised.
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Affiliation(s)
- Paul M Matthews
- Imperial College London, Division of Brain Sciences, Department of Medicine , E515, Burlington Danes Building, Du Cane Road, W12 0NN London , UK +44 02075942612 ; +44 02075946548 ;
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15
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Fowler JS, Logan J, Shumay E, Alia-Klein N, Wang GJ, Volkow ND. Monoamine oxidase: radiotracer chemistry and human studies. J Labelled Comp Radiopharm 2015; 58:51-64. [PMID: 25678277 DOI: 10.1002/jlcr.3247] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 10/31/2014] [Indexed: 11/09/2022]
Abstract
Monoamine oxidase (MAO) oxidizes amines from both endogenous and exogenous sources thereby regulating the concentration of neurotransmitter amines such as serotonin, norepinephrine, and dopamine as well as many xenobiotics. MAO inhibitor drugs are used in the treatment of Parkinson's disease and in depression stimulating the development of radiotracer tools to probe the role of MAO in normal human biology and in disease. Over the past 30 years since the first radiotracers were developed and the first positron emission tomography (PET) images of MAO in humans were carried out, PET studies of brain MAO in healthy volunteers and in patients have identified different variables that have contributed to different MAO levels in brain and in peripheral organs. MAO radiotracers and PET have also been used to study the current and developing MAO inhibitor drugs including the selection of doses for clinical trials. In this article, we describe the following: (1) the development of MAO radiotracers; (2) human studies including the relationship of brain MAO levels to genotype, personality, neurological, and psychiatric disorders; and (3) examples of the use of MAO radiotracers in drug research and development. We will conclude with outstanding needs to improve the radiotracers that are currently used and possible new applications.
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Affiliation(s)
- Joanna S Fowler
- Biological, Environmental and Climate Sciences Department, Brookhaven National Laboratory, Upton, NY, USA
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16
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Amhaoul H, Staelens S, Dedeurwaerdere S. Imaging brain inflammation in epilepsy. Neuroscience 2014; 279:238-52. [DOI: 10.1016/j.neuroscience.2014.08.044] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 08/27/2014] [Accepted: 08/27/2014] [Indexed: 01/15/2023]
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17
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Tegler G, Estrada S, Hall H, Wanhainen A, Björck M, Sörensen J, Antoni G. Autoradiography screening of potential positron emission tomography tracers for asymptomatic abdominal aortic aneurysms. Ups J Med Sci 2014; 119:229-35. [PMID: 24555564 PMCID: PMC4116762 DOI: 10.3109/03009734.2014.894157] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
OBJECTIVE The aetiology and early pathophysiological mechanisms of aortic aneurysm formation are still unknown and challenging to study in vivo. Positron emission tomography (PET) is a potentially valuable instrument for non-invasive in vivo pathophysiological studies. No specific tracer to identify the pathophysiological process of aneurysmal dilatation is yet available, however. The aim of this study was to explore if different PET tracers could be useful to image aneurysmal disease. METHODS AND RESULTS Human aneurysmal aortic tissue, collected during elective resection of abdominal aortic aneurysm (AAA) of asymptomatic patients, was investigated in vitro by means of autoradiography with [(68)Ga]CRP-binder targeting C-reactive protein, [(11)C]DAA1106 targeting translocator protein (18 kDa), [(11)C]D-deprenyl with unknown target receptor, [(11)C]deuterium-L-deprenyl targeting astrocytes, [(18)F]fluciclatide targeting integrin αVβ3, [(68)Ga]IMP461 and bi-specific antibody TF2 052107 targeting carcinoembryonic antigen, [(18)F]F-metomidate targeting mitochondrial cytochrome P-450 species in the adrenal cortex, and [(18)F]vorozole targeting aromatase. Of the investigated tracers, only [(18)F]fluciclatide exhibited specific binding, whereas the other PET tracers failed to show specific uptake in the investigated tissue and are probably not useful for the intended purpose. CONCLUSION It seems likely that αVβ3 integrin expression in AAA can be visualized with PET and that the αVβ3 selective tracer, [(18)F]fluciclatide, may be suitable for in vivo molecular imaging of asymptomatic AAA. Additional evaluation of [(18)F]fluciclatide and αVβ3 integrin expression in AAA will be performed in vitro as well as in vivo.
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Affiliation(s)
- Gustaf Tegler
- Department of Surgical Sciences, Section of Vascular Surgery, Uppsala University, Uppsala, Sweden
| | - Sergio Estrada
- Platform for Preclinical PET, Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden
| | - Håkan Hall
- Platform for Preclinical PET, Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden
| | - Anders Wanhainen
- Department of Surgical Sciences, Section of Vascular Surgery, Uppsala University, Uppsala, Sweden
| | - Martin Björck
- Department of Surgical Sciences, Section of Vascular Surgery, Uppsala University, Uppsala, Sweden
| | - Jens Sörensen
- Nuclear Medicine and PET, Department of Radiology and Oncology and Radiation Sciences, Uppsala University, Uppsala, Sweden
- PET Centre, Uppsala University, Uppsala, Sweden
| | - Gunnar Antoni
- Platform for Preclinical PET, Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden
- PET Centre, Uppsala University, Uppsala, Sweden
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Abstract
Among various neuroimaging techniques used for the evaluation of children with intractable epilepsy, positron emission tomography (PET) employing various PET tracers plays a very important role, especially in localizing areas of focal cortical dysplasia. This is particularly important in infants, where incomplete myelination may limit the structural information provided by MRI. In children with tuberous sclerosis, PET can differentiate between epileptogenic and nonepileptogenic tubers, previously not thought to be possible with neuroimaging. PET may reveal cortical or subcortical abnormalities in various epilepsy syndromes, such as infantile spasms and Landau-Kleffner syndrome. Various other applications of PET have included the investigation of epileptic networks, secondary epileptic foci, dual pathology, and neuroinflammation. Finally, PET can also be used to evaluate various cognitive processes and their underlying neurological substrates and can help in addressing the issue of brain plasticity and reorganization, related to epilepsy.
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Affiliation(s)
- Ajay Kumar
- Departments of Pediatrics and Neurology, School of Medicine, Wayne State University, and PET Center, Children's Hospital of Michigan, Detroit, MI, USA
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19
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Dopamine abnormalities in the neocortex of patients with temporal lobe epilepsy. Neurobiol Dis 2012; 45:499-507. [DOI: 10.1016/j.nbd.2011.09.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Revised: 09/03/2011] [Accepted: 09/13/2011] [Indexed: 11/20/2022] Open
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20
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Distribution and binding of 18F-labeled and 125I-labeled analogues of ACI-80, a prospective molecular imaging biomarker of disease: a whole hemisphere post mortem autoradiography study in human brains obtained from Alzheimer's disease patients. Neurochem Int 2011; 60:153-62. [PMID: 22100791 DOI: 10.1016/j.neuint.2011.10.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2011] [Revised: 10/23/2011] [Accepted: 10/25/2011] [Indexed: 01/23/2023]
Abstract
One of the major pathological landmarks of Alzheimer's disease and other neurodegenerative diseases is the presence of amyloid deposits in the brain. The early non-invasive visualization of amyloid is a major objective of recent diagnostic neuroimaging approaches, including positron emission tomography (PET), with an eye on follow-up of disease progression and/or therapy efficacy. The development of molecular imaging biomarkers with binding affinity to amyloid in the brain is therefore in the forefront of imaging biomarker and radiochemistry research. Recently, a dodecamer peptide (amino acid sequence=QSHYRHISPAQV; denominated D1 or ACI-80) was identified as a prospective ligand candidate, binding with high ex vivo affinity to L-Aβ-amyloid (K(d): 0.4 μM). In order to assess the ligand's capacity to visualize amyloid in Alzheimer's disease (AD), two (125)I labeled and three (18)F labeled analogues of the peptide were synthesized and tested in post mortem human autoradiography experiments using whole hemisphere brain slices obtained from deceased AD patients and age matched control subjects. The (18)F-labeled radioligands showed more promising visualization capacity of amyloid that the (125)I-labeled radioligands. In the case of each (18)F radioligands the grey matter uptake in the AD brains was significantly higher than that in control brains. Furthermore, the grey matter: white matter uptake ratio was over ~2, the difference being significant for each (18)F-radioligands. The regional distribution of the uptake of the various radioligands systematically shows a congruent pattern between the high uptake regions and spots in the autoradiographic images and the disease specific signals obtained in adjacent or identical brain slices labeled with histological, immunohistochemical or autoradiographic stains for amyloid deposits or activated astrocytes. The present data, using post mortem human brain autoradiography in whole hemisphere human brains obtained from deceased AD patients and age matched control subjects, support the visualization capacity of the radiolabeled ACI-80 analogues of amyloid deposits in the human brain. Further studies are warranted to explore the usefulness of the (18)F-labeled analogues as in vivo molecular imaging biomarkers in diagnostic PET studies.
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Gulyás B, Pavlova E, Kása P, Gulya K, Bakota L, Várszegi S, Keller E, Horváth MC, Nag S, Hermecz I, Magyar K, Halldin C. Activated MAO-B in the brain of Alzheimer patients, demonstrated by [11C]-L-deprenyl using whole hemisphere autoradiography. Neurochem Int 2010; 58:60-8. [PMID: 21075154 DOI: 10.1016/j.neuint.2010.10.013] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Revised: 10/24/2010] [Accepted: 10/26/2010] [Indexed: 11/25/2022]
Abstract
In the human brain the monoaminooxidase-B enzyme or MAO-B is highly abundant in astrocytes. As astrocyte activity and, consequently, the activity of the MAO-B enzyme, is up-regulated in neuroinflammatory processes, radiolabelled analogues of deprenyl may serve as an imaging biomarker in neuroinflammation and neurodegeneration, including Alzheimer's disease. In the present study [(11)C]-L-deprenyl, the PET radioligand version of L-deprenyl or selegiline®, a selective irreversible MAO-B inhibitor was used in whole hemisphere autoradiographic experiments in human brain sections in order to test the radioligand's binding to the MAO-B enzyme in human brain tissue, with an eye on exploring the radioligand's applicability as a molecular imaging biomarker in human PET studies, with special regard to diagnostic detection of reactive astrogliosis. Whole hemisphere brain sections obtained from Alzheimer patients and from age matched control subjects were examined. In control brains the binding of [(11)C]-L-deprenyl was the highest in the hippocampus, in the basal ganglia, the thalamus, the substantia nigra, the corpus geniculatum laterale, the nucleus accumbens and the periventricular grey matter. In Alzheimer brains significantly higher binding was observed in the temporal lobes and the white matter. Furthermore, in the Alzheimer brains in the hippocampus, temporal lobe and white matter the binding negatively correlated with Braak stages. The highest binding was observed in Braak I-II, whereas it decreased with increasing Braak grades. The increased regional binding in Alzheimer brains coincided with the presence of an increased number of activated astrocytes, as demonstrated by correlative immunohistochemical studies with GFAP in adjacent brain slices. Deprenyl itself as well as the MAO-B antagonist rasagiline did effectively block the binding of the radioligand, whereas the MAO-A antagonist pirlindole did not affect it. Compounds with high affinity for the PBR system did not block the radioligand binding either, providing evidence for the specificity of [(11)C]-L-deprenyl for the MAO-B enzyme. In conclusion, the present observations indicate that [(11)C]-L-deprenyl may be a promising and selective imaging biomarker of increased MAO-B activity in the human brain and can therefore serve as a prospective PET tracer targeting neuroinflammation and neurodegeneration.
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Affiliation(s)
- Balázs Gulyás
- Karolinska Institutet, Department of Clinical Neuroscience, Stockholm, Sweden.
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22
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Cascino GD, Theodore WH. EPILEPSY SURGERY AND ELECTRONIC DEVICES. Continuum (Minneap Minn) 2010; 16:179-98. [DOI: 10.1212/01.con.0000368238.49610.77] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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23
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The norepinephrine transporter (NET) radioligand (S,S)-[18F]FMeNER-D2 shows significant decreases in NET density in the human brain in Alzheimer's disease: A post-mortem autoradiographic study. Neurochem Int 2010; 56:789-98. [DOI: 10.1016/j.neuint.2010.03.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2010] [Accepted: 03/01/2010] [Indexed: 11/19/2022]
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Abstract
Studies using positron emission tomography (PET) have advanced our pathophysiological and biochemical understanding of focal and generalized epilepsies. H(2) (15)O PET allows quantification of cerebral blood flow and (18)F-fluorodeoxyglucose-PET quantification of cerebral glucose metabolism. Neurotransmitters are directly responsible for modulating synaptic activity and newer PET tracers can provide information about synaptic activity and specific ligand-receptor relationships, which are important for epileptogenesis and the spread of epileptic activity.
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Affiliation(s)
- Matthias J Koepp
- National Hospital for Neurology and Neurosurgery, Queen Square, London, UK.
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25
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Sood S, Chugani HT. Functional neuroimaging in the preoperative evaluation of children with drug-resistant epilepsy. Childs Nerv Syst 2006; 22:810-20. [PMID: 16799821 DOI: 10.1007/s00381-006-0137-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2006] [Indexed: 10/24/2022]
Abstract
UNLABELLED FUNCTIONAL NEUROIMAGING: Although the primary imaging modality in the management of epilepsy is magnetic resonance imaging MRI, functional neuroimaging with positron-emission tomography (PET) and single photon emission computed tomography (SPECT) often provides complementary information and, in a number of situations, provides unique information that cannot be obtained with MRI. The most commonly used PET tracers used for epilepsy evaluation are 2-deoxy-2-[(18)F]fluoro-D: -glucose (FDG) and [(11)C]flumazenil (FMZ). Recently, interictal PET with alpha-[(11)C]methyl-L: -tryptophan was found to be highly specific for the epileptic focus and can differentiate between epileptogenic and nonepileptogenic lesions in the same patient (e.g., in patients with tuberous sclerosis). DISCUSSION In this review, we discuss clinical applications of these three PET tracers in drug-resistant temporal and extratemporal lobe epilepsy, selected epilepsy syndromes of childhood, lesional and nonlesional epilepsy, and the challenges of imaging secondary epileptic foci. A brief discussion of SPECT applications in epilepsy is also included. With further development of new tracers highly sensitive and specific for epileptogenic brain regions, the presurgical evaluation of refractory epilepsy will be greatly facilitated. Approximately 0.5 to 1.0% of the population suffer from epilepsy, of which 15-20% are intractable. Infants and children, whose seizures have a focal onset are refractory to anticonvulsants and are prolonged, tend to have the worst cognitive outcome [Meador KJ, Neurology 58 (Suppl 5):S21-S26, 2002]. Seizures themselves affect the developing brain and contribute to an adverse neurologic outcome (Holmes, Pediatric Neurology 33:1-110, 2005). CONCLUSION Therefore, in treating children with intractable epilepsy, it is important to consider seizure control and to give allowance for normal cognitive development.
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Affiliation(s)
- Sandeep Sood
- Department of Neurosurgery, Children's Hospital of Michigan, Wayne State University, Detroit, MI, USA
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26
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Abstract
FDG-PET is being increasingly applied to pediatric conditions, particularly in oncology. PET and PET/CT scanning in children are not currently supported by Centers for Medicare and Medicaid Services unless the disease condition coincides with a reimbursed adult condition. The recent merger of the Children's Cancer Group and the Pediatric Oncology Group to form the Children's Oncology Group creates an opportunity to examine the use of FDG-PET in the management of childhood tumors in multi-institutional, cooperative efforts. The interest in incorporating PET imaging technology in pediatric medicine has been evidenced by several recent review articles summarizing the ongoing progress in this area. Future data will show that FDG-PET provides useful diagnostic information and can play a pivotal role in the clinical management and care of children with disease.
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Affiliation(s)
- Hossein Jadvar
- Division of Nuclear Medicine, Department of Radiology, Keck School of Medicine, University of Southern California, 1200 North State Street, GNH 5250, Los Angeles, CA 90033, USA.
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27
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Hammers A. Flumazenil positron emission tomography and other ligands for functional imaging. Neuroimaging Clin N Am 2004; 14:537-51. [PMID: 15324863 DOI: 10.1016/j.nic.2004.04.012] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Most PET receptor studies in idiopathic generalized epilepsy conducted to date include only small numbers of patients and should be interpreted with caution. Differences between earlier and later studies can largely be explained by different inclusion criteria and improving methodology. The finding of some increase of GABAA receptor binding in IGE has a potential pathologic basis in microdysgenesis. Future studies aiming to elucidate the pathophysiology of IGEs may benefit from the use of subtype-specific opioid ligands, available now, and GABAB ligands, if and when they become available.
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Affiliation(s)
- Alexander Hammers
- Department of Clinical and Experimental Epilepsy, Institute of Neurology, University College London, 33 Queen Square, London WC1N 3BG, UK.
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28
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Siegel AM. Presurgical evaluation and surgical treatment of medically refractory epilepsy. Neurosurg Rev 2003; 27:1-18; discussion 19-21. [PMID: 14586764 DOI: 10.1007/s10143-003-0305-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2003] [Accepted: 06/05/2003] [Indexed: 11/29/2022]
Abstract
Thanks to today's modern imaging examination techniques and especially to the common use of intracranial electrodes for localizing seizure foci, more and more patients with partial epilepsy can be treated microsurgically. The results of such neurosurgical therapies are very good, particularly in mesial temporal lobe epilepsy. In recent years, good results (60-70% seizure freedom) have also been achieved in extratemporal epilepsy surgery, so that such procedures can now be recommended for carefully selected patients. In this review, presurgical evaluations and the different surgical approaches are presented.
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Affiliation(s)
- Adrian M Siegel
- Epilepsy Program, Department of Neurology, University Hospital of Zurich, Frauenklinikstrasse 26, 8091, Zurich, Switzerland.
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29
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Trampal C, Engler H. [PET in neurology and psychiatry. II]. REVISTA ESPANOLA DE MEDICINA NUCLEAR 2002; 21:439-55; quiz 456-60. [PMID: 12425894 DOI: 10.1016/s0212-6982(02)72123-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- C Trampal
- Uppsala University PET Centre. Uppsala. Sweden.
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30
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Kumlien E, Nilsson A, Hagberg G, Långström B, Bergström M. PET with 11C-deuterium-deprenyl and 18F-FDG in focal epilepsy. Acta Neurol Scand 2001; 103:360-6. [PMID: 11421848 DOI: 10.1034/j.1600-0404.2001.103006360.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVES This study compares positron emission tomography (PET) using 11C-deuterium-deprenyl (DED) with PET using 18F-fluorodeoxyglucose(18F-FDG) for examining epileptogenic regions in patients with focal epilepsy. MATERIAL AND METHODS Twenty-three patients undergoing evaluation for epilepsy surgery were subjected to PET with DED. Fourteen patients had mesial temporal lobe epilepsy (TLE) and 9 patients had seizures of neocortical origin. In addition, 6 healthy control subjects were examined. Pixel-by-pixel analysis was used to generate graphical images of tracer distribution volume (intercept) and the accumulation rate (slope). Asymmetries with respect to relative intercept and slope were compared in patients with temporal lobe epilepsy (TLE), in patients with extra-temporal lobe epilepsy (exTLE), and in the control subjects. The results were compared with 18F-FDG-PET. RESULTS Among the patients with TLE, significant differences between the epileptogenic and the contralateral lobe were found with DED intercept and FDG-uptake. No significant differences were found with DED slope. The exTLE and the control groups showed no significant differences between sides or lobes. CONCLUSIONS This study indicates that PET with 11C-deuterium-deprenyl is a useful method for identifying TLE and is equivalent to PET with 18F-FDG in this sense. The method has little localizing value in seizures originating from neocortical structures.
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Affiliation(s)
- E Kumlien
- Department of Neuroscience, Neurology and Uppsala University PET Centre, University Hospital, S-751 85 Uppsala, Sweden.
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31
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Richardson MP. CPD - education and self-assessment: functional imaging in epilepsy. Seizure 2001; 10:139-56. [PMID: 11407959 DOI: 10.1053/seiz.2001.0546] [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: 11/11/2022] Open
Abstract
Functional imaging plays a growing role in the clinical assessment and research investigation of patients with epilepsy. This article reviews the literature on functional MRI (fMRI) investigation of EEG activity, fMRI evaluation of cognitive and motor functions, magnetic resonance spectroscopy (MRS), single photon emission computed tomography (SPECT) and positron emission tomography (PET) in epilepsy. The place of these techniques in clinical evaluation and their contribution to a better neurobiological understanding of epilepsy are discussed.
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Affiliation(s)
- M P Richardson
- Medical Research Council Fellow, Institute of Neurology, University College London, UK.
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32
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Juhász C, Chugani DC, Muzik O, Watson C, Shah J, Shah A, Chugani HT. Relationship between EEG and positron emission tomography abnormalities in clinical epilepsy. J Clin Neurophysiol 2000; 17:29-42. [PMID: 10709809 DOI: 10.1097/00004691-200001000-00004] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Positron emission tomography (PET) is a relatively noninvasive neuroimaging method by means of which a large variety of human brain functions can be assessed. Localized neurochemical abnormalities detected by PET were found in patients with partial epilepsy and suggested the use of this modality for localizing epileptogenic regions of the brain. The clinical usefulness of PET is determined by its sensitivity and specificity for identifying epileptogenic areas as defined by ictal surface and intracranial EEG recordings. The findings obtained from comparative EEG and glucose PET data are reviewed with special emphasis on patients undergoing presurgical evaluation because of medically intractable temporal and extratemporal lobe epilepsy. The utility of glucose PET studies for identifying regions of seizure onset is presented, and the limited specificity of glucose metabolic abnormalities for the detection of various EEG patterns in clinical epilepsy is discussed. The authors review the available intracranial EEG and PET comparisons using [11C]flumazenil (FMZ) PET, a tracer for the assessment of tau-amino-butyric acid/benzodiazepine receptor function. They also summarize their experience with [11C]flumazenil PET in identifying cortical regions that show various ictal and interictal cortical EEG abnormalities in patients with extratemporal seizure origin. Finally, the authors demonstrate that further development of new PET tracers, such as alpha-[11C]methyl-L-tryptophan, is feasible and clinically useful and may increase the number of patients in whom PET studies can replace invasive EEG monitoring.
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Affiliation(s)
- C Juhász
- Department of Pediatrics, Children's Hospital of Michigan, Detroit Medical Center, Wayne State University School of Medicine, 48201, USA
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33
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Bergström M, Kumlien E, Lilja A, Tyrefors N, Westerberg G, Långström B. Temporal lobe epilepsy visualized with PET with 11C-L-deuterium-deprenyl--analysis of kinetic data. Acta Neurol Scand 1998; 98:224-31. [PMID: 9808270 DOI: 10.1111/j.1600-0404.1998.tb07300.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVES The purpose of the study was to develop a simplified method for the acquisition and analysis of data from positron emission tomography (PET) using the ligand 11C-L-deuterium-deprenyl. This is motivated by an increased interest in methods to characterize gliosis in neurodegenerative diseases and epilepsy, which can be defined due to an increased expression of the enzyme MAO-B. METHODS Seven patients with temporal lobe epilepsy were investigated with PET. The tracer kinetics in different brain structures was recorded and analyzed using different models with and without a plasma input function. The derived values were correlated to literature values of 3H-deprenyl binding in frozen sections from normal human brains. RESULTS A good correlation was seen between in vivo binding and in vitro data, with the correlation being equally good irrespective of whether metabolite corrected plasma or modified cerebellar uptake values were used as input function. The epileptic lobe was, compared to non-epileptic, characterized by a lower initial distribution and an enhanced late accumulation of the tracer. With the applied method, it was possible to correctly identify the epileptic side in all 6 unilateral patients and I probable bilateral case. CONCLUSIONS PET with 11C-L-deuterium-deprenyl gives a good correlation between calculated in vivo binding and MAO-B activity. The analysis can be simplified and blood sampling avoided if modified cerebellar time-activity data is used as a reference. Separate images of distribution volume and MAO-B binding can be generated.
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Affiliation(s)
- M Bergström
- Uppsala University PET Centre, Uppsala University, Sweden
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34
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Duncan JS. Positron Emission Tomography Receptor Studies. Epilepsia 1997. [DOI: 10.1111/j.1528-1157.1997.tb00093.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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35
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Fowler JS, Volkow ND, Wang GJ, Logan J, Pappas N, Shea C, MacGregor R. Age-related increases in brain monoamine oxidase B in living healthy human subjects. Neurobiol Aging 1997; 18:431-5. [PMID: 9330975 DOI: 10.1016/s0197-4580(97)00037-7] [Citation(s) in RCA: 180] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Several studies of human brain postmortem report that monoamine oxidase B (MAO B) increases with age and it has been proposed that this increase reflects age-associated increases in glial cells. We measured brain MAO B in a group of normal healthy human subjects (n = 21; age range 23-86; 9 females and 12 males; nonsmokers) using [11C]L-deprenyl-D2 and positron emission tomography. Brain glucose metabolism was also measured with 18FDG in 15 of the subjects. MAO B increased (p < 0.004) in all brain regions examined except the cingulate gyrus. In contrast, subjects showed the expected regional age-related decreases in blood flow and metabolism. In the 15 subjects in whom both MAO B and LCMRglu was measured, there was a trend (p < 0.03) toward an inverse association between brain glucose metabolism and MAO B activity in the frontal and parietal cortices. Although the age-related increase in brain MAO B in living subjects is consistent with postmortem reports, the degree of increase is generally lower.
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Affiliation(s)
- J S Fowler
- Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973, USA
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36
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Abstract
Epilepsy research using positron emission tomography (PET) has provided considerable new information about ictal and interictal dysfunctions in human epilepsy. Neuroreceptor mapping with PET ligands has revealed altered central benzodiazepine receptor and opiate receptor densities in partial epilepsies interictally, and regional increases in endogenous opioid peptide concentrations during absence seizures. Imaging of perfusion and glucose metabolism during cognitive processing has shown interictal abnormalities of regional activation in partial and generalized epilepsies. The diagnostically robust patterns of interictal glucose hypometabolism are not adequately explained by macrostructural and microstructural alterations in temporal lobe epilepsy. Current investigations of the pathophysiology of interictal hypometabolism must address ultrastructural and neurochemical factors. Clinical PET in presurgical evaluation of medically refractory epilepsies remains an active area of research, but remarkably little antiepileptic drug research has exploited PET techniques.
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MESH Headings
- Anticonvulsants/pharmacokinetics
- Anticonvulsants/pharmacology
- Brain/diagnostic imaging
- Brain/metabolism
- Brain/physiopathology
- Cerebrovascular Circulation
- Deoxyglucose/analogs & derivatives
- Epilepsy/diagnostic imaging
- Epilepsy/metabolism
- Epilepsy/physiopathology
- Epilepsy, Temporal Lobe/diagnostic imaging
- Epilepsy, Temporal Lobe/metabolism
- Epilepsy, Temporal Lobe/physiopathology
- Flumazenil/metabolism
- Fluorodeoxyglucose F18
- Glucose/metabolism
- Humans
- Oxygen Radioisotopes/metabolism
- Receptors, GABA-A/metabolism
- Receptors, GABA-A/physiology
- Receptors, Muscarinic/metabolism
- Receptors, Muscarinic/physiology
- Receptors, Opioid/metabolism
- Receptors, Opioid/physiology
- Tomography, Emission-Computed
- Water
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Affiliation(s)
- T R Henry
- Department of Neurology, Entory University School of Medicine, Atlanta, Georgia, USA
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37
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Abstract
We studied the distribution of felbamate (FBM) in rat brain using a br ain imaging scanner to analyze thaw-mount autoradiographs. After intravenous injection of 14 C FBM in rats, the autoradiograph distribution of isotope labeling patterns in brain was captured on x-ray film. Densitometric differences on the x-ray film were converted into color-code variations representing the different concentrations of FBM in regions of the brain. We demonstrated that relatively uniform concentrations of FBM were detected throughout the brain. In all brain regions examined, there were no specifically high or low concentrations of FBM. We conclude that the FBM distributes uniformly.
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Affiliation(s)
- E M Cornford
- West Los Angeles Veterans Administration Medical Center, California, USA
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