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Kuroda H, Yamamoto D, Koizumi H, Shimizu S, Kumabe T. Cortical Neural Damage Associated with Cerebral Hyperperfusion after Reperfusion Therapy for Acute Ischemic Stroke: 123I-iomazenil Single-photon Emission Computed Tomography Findings. NMC Case Rep J 2022; 8:367-370. [PMID: 35079490 PMCID: PMC8769473 DOI: 10.2176/nmccrj.cr.2020-0284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 10/28/2020] [Indexed: 12/04/2022] Open
Abstract
We present an 88-year-old man with cerebral hyperperfusion (CH) after acute reperfusion therapy. He developed acute cerebral ischemia as a result of occluded middle cerebral artery that was subsequently recanalized with endovascular thrombectomy. I-123 N-isopropyl-p-iodoamphetamine single-photon emission computed tomography (SPECT) after reperfusion therapy showed increased cerebral blood flow (CBF) in brain areas that exhibited no abnormal findings on magnetic resonance imaging (MRI). Follow-up MRI did not demonstrate structural brain damage associated with CH. However, later I-123 iomazenil SPECT imaging showed a reduction in benzodiazepine receptor binding potential (BRBP) in these areas, a finding that correlates with cortical neural damage. CH is being increasingly observed after endovascular treatment for acute stroke. However, little is known about CH when not associated with cerebral hemorrhage or infarction. The role of CH after reperfusion therapy in causing brain damage remains unclear. BRBP on I-123 iomazenil SPECT images is useful to evaluate brain neural density: a reduction in cortical BRBP indicates cortical neural damage or loss. Our findings suggest that post-reperfusion hyperperfusion induces cortical neural damage even in the absence of associated brain infarction or hemorrhage on MRI. Early postoperative SPECT is recommended to detect CH after acute reperfusion therapy. CH should be considered when the recovery from stroke is unexpectedly poor for a patient.
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Affiliation(s)
- Hiroki Kuroda
- Department of Neurosurgery, Yokohama Brain and Spine Center, Yokohama, Kanagawa, Japan.,Department of Neurosurgery, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
| | - Daisuke Yamamoto
- Department of Neurosurgery, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
| | - Hiroyuki Koizumi
- Department of Neurosurgery, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
| | - Satoru Shimizu
- Department of Neurosurgery, Yokohama Brain and Spine Center, Yokohama, Kanagawa, Japan
| | - Toshihiro Kumabe
- Department of Neurosurgery, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
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Szöllősi D, Hegedűs N, Veres DS, Futó I, Horváth I, Kovács N, Martinecz B, Dénes Á, Seifert D, Bergmann R, Lebeda O, Varga Z, Kaleta Z, Szigeti K, Máthé D. Evaluation of Brain Nuclear Medicine Imaging Tracers in a Murine Model of Sepsis-Associated Encephalopathy. Mol Imaging Biol 2019; 20:952-962. [PMID: 29736562 PMCID: PMC6244542 DOI: 10.1007/s11307-018-1201-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Purpose The purpose of this study was to evaluate a set of widely used nuclear medicine imaging agents as possible methods to study the early effects of systemic inflammation on the living brain in a mouse model of sepsis-associated encephalopathy (SAE). The lipopolysaccharide (LPS)-induced murine systemic inflammation model was selected as a model of SAE. Procedures C57BL/6 mice were used. A multimodal imaging protocol was carried out on each animal 4 h following the intravenous administration of LPS using the following tracers: [99mTc][2,2-dimethyl-3-[(3E)-3-oxidoiminobutan-2-yl]azanidylpropyl]-[(3E)-3-hydroxyiminobutan-2-yl]azanide ([99mTc]HMPAO) and ethyl-7-[125I]iodo-5-methyl-6-oxo-4H-imidazo[1,5-a][1,4]benzodiazepine-3-carboxylate ([125I]iomazenil) to measure brain perfusion and neuronal damage, respectively; 2-deoxy-2-[18F]fluoro-d-glucose ([18F]FDG) to measure cerebral glucose uptake. We assessed microglia activity on another group of mice using 2-[6-chloro-2-(4-[125I]iodophenyl)-imidazo[1,2-a]pyridin-3-yl]-N-ethyl-N-methyl-acetamide ([125I]CLINME). Radiotracer uptakes were measured in different brain regions and correlated. Microglia activity was also assessed using immunohistochemistry. Brain glutathione levels were measured to investigate oxidative stress. Results Significantly reduced perfusion values and significantly enhanced [18F]FDG and [125I]CLINME uptake was measured in the LPS-treated group. Following perfusion compensation, enhanced [125I]iomazenil uptake was measured in the LPS-treated group’s hippocampus and cerebellum. In this group, both [18F]FDG and [125I]iomazenil uptake showed highly negative correlation to perfusion measured with ([99mTc]HMPAO uptake in all brain regions. No significant differences were detected in brain glutathione levels between the groups. The CD45 and P2Y12 double-labeling immunohistochemistry showed widespread microglia activation in the LPS-treated group. Conclusions Our results suggest that [125I]CLINME and [99mTc]HMPAO SPECT can be used to detect microglia activation and brain hypoperfusion, respectively, in the early phase (4 h post injection) of systemic inflammation. We suspect that the enhancement of [18F]FDG and [125I]iomazenil uptake in the LPS-treated group does not necessarily reflect neural hypermetabolism and the lack of neuronal damage. They are most likely caused by processes emerging during neuroinflammation, e.g., microglia activation and/or immune cell infiltration. Electronic supplementary material The online version of this article (10.1007/s11307-018-1201-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Dávid Szöllősi
- Department of Biophysics and Radiation Biology, Semmelweis Univ, Budapest, H-1094, Hungary
| | - Nikolett Hegedűs
- Department of Biophysics and Radiation Biology, Semmelweis Univ, Budapest, H-1094, Hungary
| | - Dániel S Veres
- Department of Biophysics and Radiation Biology, Semmelweis Univ, Budapest, H-1094, Hungary
| | - Ildikó Futó
- Department of Biophysics and Radiation Biology, Semmelweis Univ, Budapest, H-1094, Hungary
| | - Ildikó Horváth
- Department of Biophysics and Radiation Biology, Semmelweis Univ, Budapest, H-1094, Hungary
| | - Noémi Kovács
- CROmed Translational Research Centers, Budapest, H-1047, Hungary
| | - Bernadett Martinecz
- Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary
| | - Ádám Dénes
- Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary
| | - Daniel Seifert
- Nuclear Physics Institute of the CAS, CZ 250 68, Rez, Czech Republic
| | - Ralf Bergmann
- Helmholz-Zentrum Dresden-Rossendorf, Radiopharmazie Radiopharmaceutische Biologie, Dresden, Germany
| | - Ondřej Lebeda
- Nuclear Physics Institute of the CAS, CZ 250 68, Rez, Czech Republic
| | - Zoltán Varga
- Department of Biophysics and Radiation Biology, Semmelweis Univ, Budapest, H-1094, Hungary.,Biological Nanochemistry Research Group, Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - Zoltán Kaleta
- Progressio Fine Chemical Engineering Ltd, Székesfehérvár, Hungary
| | - Krisztián Szigeti
- Department of Biophysics and Radiation Biology, Semmelweis Univ, Budapest, H-1094, Hungary.
| | - Domokos Máthé
- CROmed Translational Research Centers, Budapest, H-1047, Hungary
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Desrues L, Lefebvre T, Lecointre C, Schouft MT, Leprince J, Compère V, Morin F, Proust F, Gandolfo P, Tonon MC, Castel H. Down-regulation of GABA(A) receptor via promiscuity with the vasoactive peptide urotensin II receptor. Potential involvement in astrocyte plasticity. PLoS One 2012; 7:e36319. [PMID: 22563490 PMCID: PMC3341351 DOI: 10.1371/journal.pone.0036319] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 04/02/2012] [Indexed: 02/07/2023] Open
Abstract
GABAA receptor (GABAAR) expression level is inversely correlated with the proliferation rate of astrocytes after stroke or during malignancy of astrocytoma, leading to the hypothesis that GABAAR expression/activation may work as a cell proliferation repressor. A number of vasoactive peptides exhibit the potential to modulate astrocyte proliferation, and the question whether these mechanisms may imply alteration in GABAAR-mediated functions and/or plasma membrane densities is open. The peptide urotensin II (UII) activates a G protein-coupled receptor named UT, and mediates potent vasoconstriction or vasodilation in mammalian vasculature. We have previously demonstrated that UII activates a PLC/PIPs/Ca2+ transduction pathway, via both Gq and Gi/o proteins and stimulates astrocyte proliferation in culture. It was also shown that UT/Gq/IP3 coupling is regulated by the GABAAR in rat cultured astrocytes. Here we report that UT and GABAAR are co-expressed in cerebellar glial cells from rat brain slices, in human native astrocytes and in glioma cell line, and that UII inhibited the GABAergic activity in rat cultured astrocytes. In CHO cell line co-expressing human UT and combinations of GABAAR subunits, UII markedly depressed the GABA current (β3γ2>α2β3γ2>α2β1γ2). This effect, characterized by a fast short-term inhibition followed by drastic and irreversible run-down, is not relayed by G proteins. The run-down partially involves Ca2+ and phosphorylation processes, requires dynamin, and results from GABAAR internalization. Thus, activation of the vasoactive G protein-coupled receptor UT triggers functional inhibition and endocytosis of GABAAR in CHO and human astrocytes, via its receptor C-terminus. This UII-induced disappearance of the repressor activity of GABAAR, may play a key role in the initiation of astrocyte proliferation.
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Affiliation(s)
- Laurence Desrues
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, Astrocyte and Vascular Niche, University of Rouen, Mont-Saint-Aignan, France
- Institute of Research and Biomedical Innovation (IRIB), Normandy University PRES, University of Rouen, Mont-Saint-Aignan, France
| | - Thomas Lefebvre
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, Astrocyte and Vascular Niche, University of Rouen, Mont-Saint-Aignan, France
- Institute of Research and Biomedical Innovation (IRIB), Normandy University PRES, University of Rouen, Mont-Saint-Aignan, France
| | - Céline Lecointre
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, Astrocyte and Vascular Niche, University of Rouen, Mont-Saint-Aignan, France
- Institute of Research and Biomedical Innovation (IRIB), Normandy University PRES, University of Rouen, Mont-Saint-Aignan, France
| | - Marie-Thérèse Schouft
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, Astrocyte and Vascular Niche, University of Rouen, Mont-Saint-Aignan, France
- Institute of Research and Biomedical Innovation (IRIB), Normandy University PRES, University of Rouen, Mont-Saint-Aignan, France
| | - Jérôme Leprince
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, Astrocyte and Vascular Niche, University of Rouen, Mont-Saint-Aignan, France
- Institute of Research and Biomedical Innovation (IRIB), Normandy University PRES, University of Rouen, Mont-Saint-Aignan, France
| | - Vincent Compère
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, Astrocyte and Vascular Niche, University of Rouen, Mont-Saint-Aignan, France
- Institute of Research and Biomedical Innovation (IRIB), Normandy University PRES, University of Rouen, Mont-Saint-Aignan, France
- Department of Anesthesiology and Critical Care, Rouen University Hospital, Rouen, France
| | - Fabrice Morin
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, Astrocyte and Vascular Niche, University of Rouen, Mont-Saint-Aignan, France
- Institute of Research and Biomedical Innovation (IRIB), Normandy University PRES, University of Rouen, Mont-Saint-Aignan, France
| | - François Proust
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, Astrocyte and Vascular Niche, University of Rouen, Mont-Saint-Aignan, France
- Institute of Research and Biomedical Innovation (IRIB), Normandy University PRES, University of Rouen, Mont-Saint-Aignan, France
- Department of Neurosurgery, Rouen University Hospital, Rouen, France
| | - Pierrick Gandolfo
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, Astrocyte and Vascular Niche, University of Rouen, Mont-Saint-Aignan, France
- Institute of Research and Biomedical Innovation (IRIB), Normandy University PRES, University of Rouen, Mont-Saint-Aignan, France
| | - Marie-Christine Tonon
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, Astrocyte and Vascular Niche, University of Rouen, Mont-Saint-Aignan, France
- Institute of Research and Biomedical Innovation (IRIB), Normandy University PRES, University of Rouen, Mont-Saint-Aignan, France
| | - Hélène Castel
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, Astrocyte and Vascular Niche, University of Rouen, Mont-Saint-Aignan, France
- Institute of Research and Biomedical Innovation (IRIB), Normandy University PRES, University of Rouen, Mont-Saint-Aignan, France
- * E-mail:
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Recovered neuronal viability revealed by Iodine-123-iomazenil SPECT following traumatic brain injury. J Cereb Blood Flow Metab 2010; 30:1673-81. [PMID: 20683454 PMCID: PMC3023407 DOI: 10.1038/jcbfm.2010.75] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We evaluated cortical damages following traumatic brain injury (TBI) in the acute phase with [(123)I] iomazenil (IMZ) single photon emission computed tomography (SPECT). In all, 12 patients with cerebral contusion following TBI were recruited. All patients underwent IMZ SPECT within 1 week after TBI. To investigate the changes in distribution of IMZ in the cortex in the chronic phase, after conventional treatment, patients underwent IMZ SPECT again. A decrease in the accumulation of radioligand for the central benzodiazepine receptor in the cortex corresponding to the contusion revealed with computed tomography (CT) scans and magnetic resonance imaging (MRI) were shown on IMZ SPECT in the acute phase in all patients. In 9 of 12 patients (75%), images of IMZ SPECT obtained in the chronic phase of TBI showed that areas with a decreased distribution of IMZ were remarkably reduced in comparison with those obtained in the acute phase. Both CT scans and MRI showed a normal appearance of the cortex morphologically, where the binding potential of IMZ recovered in the chronic phase. Reduced binding potential of radioligand for the central benzodiazepine receptor is considered to be an irreversible reaction; however, in this study, IMZ accumulation in the cortex following TBI was recovered in the chronic phase in several patients. [(123)I] iomazenil SPECT may have a potential to disclose a reversible vulnerability of neurons following TBI.
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Mathieu A, Vacca A, Serra A, Cauli A, Piga M, Porru G, Marrosu F, Sanna G, Piga M. Defective cerebral gamma-aminobutyric acid-A receptor density in patients with systemic lupus erythematosus and central nervous system involvement. An observational study. Lupus 2010; 19:918-26. [DOI: 10.1177/0961203310364398] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Gamma-aminobutyric acid-A (GABA-A) receptors play a crucial role in regulating neuronal excitability and cognitive functions. Single-photon emission computerized tomography (SPECT) analysis of GABA-A receptors binding by 123I-labelled Iomazenil (123I-IMZ) has been applied in some neuropsychiatric disorders to investigate conditions where GABA-A receptor density can be detected in several pathophysiological conditions. In this study we investigate cerebral GABA-A receptor density in a small series of patients with systemic lupus erythematosus (SLE) and cognitive impairment characterized by recurrent, episodic memory loss. Nine female patients with SLE and cognitive alterations underwent to a clinical neuropsychiatric evaluation including digital video-EEG, brain MRI, 99mTc-ECD brain SPECT and 123I-IMZ brain SPECT. All patients tested showed diffuse or focal GABA-A receptor density reduction. This is, to our knowledge, the first report on GABA-A receptor density abnormalities associated with cognitive defects in SLE patients. We hypothesize that in our series a decrease in GABA-A receptor density might be related to the neurological manifestations. Further studies are needed to clarify this aspect and the possible mechanisms. GABA-A receptor density impairment might be due to the SLE-related cerebral vasculopathy, or to neuronal-reacting auto-antibodies or drugs which could interfere with GABA-A receptors expression/binding. This study may support the concept that cognitive impairment in systemic lupus erythematosus could be the outcome of fine-tuned neurotransmission alterations.
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Affiliation(s)
- A. Mathieu
- Chair and AOU Unit of Rheumatology, University of Cagliari, Italy,
| | - A. Vacca
- Chair and AOU Unit of Rheumatology, University of Cagliari, Italy
| | - A. Serra
- Chair and AOU Unit of Nuclear Medicine, University of Cagliari, Italy
| | - A. Cauli
- Chair and AOU Unit of Rheumatology, University of Cagliari, Italy
| | - M. Piga
- Chair and AOU Unit of Rheumatology, University of Cagliari, Italy
| | - G. Porru
- Chair and AOU Unit of Rheumatology, University of Cagliari, Italy
| | - F. Marrosu
- Department of Neurological and Cardiovascular Sciences, University of Cagliari, Italy
| | - G. Sanna
- Lupus Research Unit The Rayne Institute, St Thomas' Hospital, London, UK
| | - M. Piga
- Chair and AOU Unit of Nuclear Medicine, University of Cagliari, Italy
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Spontaneous recovery of reduced cortical central benzodiazepine receptor binding potential on I-123 Iomazenil SPECT in a patient with status epilepticus. Clin Nucl Med 2010; 35:126-7. [PMID: 20090466 DOI: 10.1097/rlu.0b013e3181c7c168] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Eliassen JC, Boespflug EL, Lamy M, Allendorfer J, Chu WJ, Szaflarski JP. Brain-mapping techniques for evaluating poststroke recovery and rehabilitation: a review. Top Stroke Rehabil 2008; 15:427-50. [PMID: 19008203 DOI: 10.1310/tsr1505-427] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Brain-mapping techniques have proven to be vital in understanding the molecular, cellular, and functional mechanisms of recovery after stroke. This article briefly summarizes the current molecular and functional concepts of stroke recovery and addresses how various neuroimaging techniques can be used to observe these changes. The authors provide an overview of various techniques including diffusion-tensor imaging (DTI), magnetic resonance spectroscopy (MRS), ligand-based positron emission tomography (PET), single-photon emission computed tomography (SPECT), regional cerebral blood flow (rCBF) and regional metabolic rate of glucose (rCMRglc) PET and SPECT, functional magnetic resonance imaging (fMRI), near infrared spectroscopy (NIRS), electroencephalography (EEG), magnetoencephalography (MEG), and transcranial magnetic stimulation (TMS). Discussion in the context of poststroke recovery research informs about the applications and limitations of the techniques in the area of rehabilitation research. The authors also provide suggestions on using these techniques in tandem to more thoroughly address the outstanding questions in the field.
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Affiliation(s)
- James C Eliassen
- Center for Imaging Research, University of Cincinnati Academic Health Center, Cincinnati, Ohio, USA
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Tateishi N, Shimoda T, Manako JI, Katsumata S, Shinagawa R, Ohno H. Relevance of astrocytic activation to reductions of astrocytic GABAA receptors. Brain Res 2006; 1089:79-91. [PMID: 16643860 DOI: 10.1016/j.brainres.2006.02.139] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2005] [Revised: 02/15/2006] [Accepted: 02/24/2006] [Indexed: 11/22/2022]
Abstract
Although astrocytes express gamma-aminobutyric acid subtype-A (GABAA) receptors in the mature brain, GABAA receptor expression in a cultivation state remains controversial. In this study, we investigated the alteration of astrocytic GABAA receptor expression in in vitro and in vivo studies to elucidate the relevance of astrocytic activation to reductions of astrocytic GABAA receptors. The GABA-evoked Cl- current (GABAA response) in cultured astrocytes was determined by recording in the whole-cell mode using a conventional patch-clamp technique under voltage-clamp conditions. The respective amplitudes of GABAA responses on days in vitro 1, 3-5, 7-10, and 12-15 were 1019+/-97, 512+/-76, 84+/-21, and 22+/-9 pA, respectively, suggesting that the GABAA response subsequently diminished with in vitro aging. In immunohistochemical and biochemical analyses, the expression of GABAA receptor beta-subunit decreased, whereas expressions of glial fibrillary acidic protein (GFAP) and S100B, hallmarks of astrocytic activation, increased dramatically in the cultured astrocytes with in vitro aging. With the use of [3H]SR95531, a GABAA-specific ligand, at 24 h after transient focal ischemia, binding was significantly reduced in the astrocytic fractions without affecting the synaptosomal fractions, and decreases in the mRNA expression level of GABAA receptor beta-subunits were concurrently observed. Interestingly, the loss of GABAA response in cultured astrocytes was mitigated by co-culturing with neurons or treatments with monoclonal S100B antibodies. These results indicate that astrocytic GABAA receptors are reduced with in vitro aging and cerebral ischemia, presumably through the overproduction of S100B in activated astrocytes.
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Affiliation(s)
- Narito Tateishi
- Minase Research Institute, Ono Pharmaceutical Co., Ltd., 3-1-1 Sakurai, Shimamoto-cho, Mishima-gun, Osaka 618-8585, Japan.
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Shiga T, Ikoma K, Katoh C, Isoyama H, Matsuyama T, Kuge Y, Kageyama H, Kohno T, Terae S, Tamaki N. Loss of neuronal integrity: a cause of hypometabolism in patients with traumatic brain injury without MRI abnormality in the chronic stage. Eur J Nucl Med Mol Imaging 2006; 33:817-22. [PMID: 16565846 DOI: 10.1007/s00259-005-0033-y] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2005] [Accepted: 10/26/2005] [Indexed: 12/01/2022]
Abstract
PURPOSE Traumatic brain injury (TBI) causes brain dysfunction in many patients. However, some patients have severe brain dysfunction but display no abnormalities on magnetic resonance imaging (MRI). There have been some reports of hypometabolism even in such patients. The purpose of this study was to investigate the relationship between metabolic abnormality and loss of neuronal integrity in TBI patients with some symptoms but without MRI abnormalities. METHODS The study population comprised ten patients with TBI and ten normal volunteers. All of the patients were examined at least 1 year after the injury. ( 15)O-labelled gas PET and [(11)C]flumazenil (FMZ) positron emission tomography (PET) were carried out. The cerebral metabolic rate of oxygen (CMRO(2)) and binding potential (BP) images of FMZ were calculated. Axial T2WI, T2*WI and FLAIR images were obtained. Coronal images were added in some cases. RESULTS All of the patients had normal MRI findings, and all showed areas with abnormally low CMRO(2). Low uptake on BP images was observed in six patients (60%). No lesions that showed low uptake on BP images were without low CMRO(2). On the other hand, there were 14 lesions with low CMRO(2) but without BP abnormalities. CONCLUSION These results indicate that there are metabolic abnormalities in TBI patients with some symptoms after brain injury but without abnormalities on MRI. Some of the hypometabolic lesions showed low BP, indicating a loss of neuronal integrity. Thus, FMZ PET may have potential to distinguish hypometabolism caused by neuronal loss from that caused by other factors.
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Affiliation(s)
- Tohru Shiga
- Department of Nuclear Medicine, Hokkaido University School of Medicine, North 15th, West 7th, Kitaku Sapporo 060-8638, Japan.
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Chang YS, Jeong JM, Yoon YH, Kang WJ, Lee SJ, Lee DS, Chung JK, Lee MC. Biological properties of 2′-[18F]fluoroflumazenil for central benzodiazepine receptor imaging. Nucl Med Biol 2005; 32:263-8. [PMID: 15820761 DOI: 10.1016/j.nucmedbio.2004.12.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2004] [Revised: 12/23/2004] [Accepted: 12/23/2004] [Indexed: 11/15/2022]
Abstract
A novel positron emitting agent, 2'-[18F]fluoroflumazenil (fluoroethyl 8-fluoro-5-methyl-6-oxo-5,6-dihydro-4H-benzo-[f]imidazo[1,5-a][1,4]diazepine-3-carboxylate, FFMZ), has been reported for benzodiazepine imaging. In the present study, biological properties of [18F]FFMZ were investigated. Stability tests of [18F]FFMZ in human and rat sera were performed. Biodistribution was investigated in mice and phosphorimages of brains were obtained from rats. A receptor binding assay was performed using rat brain (mixture of cortex and cerebellum) homogenate. A static positron emission tomography (PET) image was obtained from a normal human volunteer. Although [18F]FFMZ was stable in human serum, it was rapidly hydrolyzed in rat serum. The hydrolysis was 39%, 63% and 92% at 10, 30 and 60 min, respectively. According to the biodistribution study in mice, somewhat even distribution (between 2 approximately 3% ID/g) was observed in most organs. Intestinal uptake increased up to 6% ID/g at 1 h due to biliary excretion. Bone uptake slowly increased from 1.5% to 3.5% ID/g at 1 h. High uptakes in the cortex, thalamus and cerebellum, which could be completely blocked by coinjection of cold FMZ, were observed by phosphorimaging study using rats. Determination of Kd value and Bmax using rat brain tissue was performed by Scatchard plotting and found 1.45+/-0.26 nM and 1.08+/-0.03 pmol/mg protein, respectively. The PET image of the normal human volunteer showed high uptake in the following decreasing order: frontal cortex, temporal cortex, occipital cortex, cerebellum, parietal cortex and thalamus. In conclusion, the new FMZ derivative, [18F]FFMZ appears to be a promising PET agent for central benzodiazepine receptor imaging with a convenient labeling procedure and a specific binding property.
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Affiliation(s)
- Young Soo Chang
- Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul 110-744, South Korea
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