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Picchioni D, Schmidt KC, Loutaev I, Pavletic AJ, Sheeler C, Bishu S, Balkin TJ, Smith CB. Increased rates of brain protein synthesis during [N1,N2] sleep: L-[1- 11C]leucine PET studies in human subjects. J Cereb Blood Flow Metab 2023; 43:59-71. [PMID: 36071616 PMCID: PMC9875345 DOI: 10.1177/0271678x221121873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 06/30/2022] [Accepted: 07/24/2022] [Indexed: 01/28/2023]
Abstract
During sleep, reduced brain energy demands provide an opportunity for biosynthetic processes like protein synthesis. Sleep is required for some forms of memory consolidation which requires de novo protein synthesis. We measured regional cerebral protein synthesis rates (rCPS) in human subjects to ascertain how rCPS is affected during sleep. Subjects underwent three consecutive L-[1-11C]leucine PET scans with simultaneous polysomnography: 1. rested awake, 2. sleep-deprived awake, 3. sleep. Measured rCPS were similar across the three conditions. Variations in sleep stage times during sleep scans were used to estimate rCPS in sleep stages under the assumption that measured rCPS is the weighted sum of rCPS in each stage, with weights reflecting time and availability of [11C]leucine in that stage. During sleep scans, subjects spent most of the time in N2, N3, and awake and very little time in N1 and REM; rCPS in N1 and REM could not be reliably estimated. When stages N1 and N2 were combined [N1,N2], estimates of rCPS were more robust. In selective regions, estimated rCPS were statistically significantly higher (30-39%) in [N1,N2] compared with N3; estimated rCPS in N3 were similar to values measured in sleep-deprived awake scans. Results indicate increased rates of protein synthesis linked to [N1,N2] sleep.
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Affiliation(s)
- Dante Picchioni
- Section on Neuroadaptation and Protein Metabolism, National
Institute of Mental Health, Bethesda, MD, USA
- Advanced Magnetic Resonance Imaging Section, National Institute
of Neurological Disorders and Stroke, Bethesda, MD, USA
- Behavioral Biology Branch, Walter Reed Army Institute of
Research, Silver Spring, MD, USA
| | - Kathleen C Schmidt
- Section on Neuroadaptation and Protein Metabolism, National
Institute of Mental Health, Bethesda, MD, USA
| | - Inna Loutaev
- Section on Neuroadaptation and Protein Metabolism, National
Institute of Mental Health, Bethesda, MD, USA
| | - Adriana J Pavletic
- Office of the Clinical Director, National Institute of Mental
Health, Bethesda, MD, USA
| | - Carrie Sheeler
- Section on Neuroadaptation and Protein Metabolism, National
Institute of Mental Health, Bethesda, MD, USA
| | - Shrinivas Bishu
- Section on Neuroadaptation and Protein Metabolism, National
Institute of Mental Health, Bethesda, MD, USA
| | - Thomas J Balkin
- Behavioral Biology Branch, Walter Reed Army Institute of
Research, Silver Spring, MD, USA
| | - Carolyn B Smith
- Section on Neuroadaptation and Protein Metabolism, National
Institute of Mental Health, Bethesda, MD, USA
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2
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Measurement of Protein Synthesis Rate in Rat by [11C]Leucine PET Imaging: Application to the TgF344-AD Model of Alzheimer’s Disease. Mol Imaging Biol 2022; 25:596-605. [PMID: 36538180 PMCID: PMC10172255 DOI: 10.1007/s11307-022-01796-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 12/03/2022] [Accepted: 12/05/2022] [Indexed: 12/24/2022]
Abstract
AbstractLong-term memory requires stable protein synthesis and is altered in Alzheimer’s disease (AD). This study aimed to implement a method to measure the cerebral protein synthesis rate (PSR) with [11C]leucine PET in vivo in rats and evaluate potential PSR alterations longitudinally (6, 12 and 18 months old) in the TgF344-AD rat model of AD. Wistar, wild-type (WT) and TgF344-AD rats (TG) were scanned for 60 min with [11C]leucine. Arterial blood activity was monitored online and with discrete whole blood and plasma samples by γ-counting in Wistar rats, WT (n = 4) and TG (n = 5). Unlabelled amino acids were measured in plasma. The sensitivity of [11C]leucine PET to measure alterations in PSR was assessed in Wistar rats by injection of PSR inhibitor anisomycin before PET acquisition. Anisomycin administration significantly reduced the net uptake rate constant (Kcplx) of [11C]leucine and PSR, proving the suitability of the method. For the longitudinal study, averaged population-based input functions were used to calculate PSR. We found a significant genotype effect on PSR (decrease in TG vs WT) only in the globus pallidus. This study suggests that [11C]leucine PET is sensitive enough to measure brain PSR in rat but that cross-sectional design with individual input function should be preferred.
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Shegani A, Kealey S, Luzi F, Basagni F, Machado JDM, Ekici SD, Ferocino A, Gee AD, Bongarzone S. Radiosynthesis, Preclinical, and Clinical Positron Emission Tomography Studies of Carbon-11 Labeled Endogenous and Natural Exogenous Compounds. Chem Rev 2022; 123:105-229. [PMID: 36399832 PMCID: PMC9837829 DOI: 10.1021/acs.chemrev.2c00398] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The presence of positron emission tomography (PET) centers at most major hospitals worldwide, along with the improvement of PET scanner sensitivity and the introduction of total body PET systems, has increased the interest in the PET tracer development using the short-lived radionuclides carbon-11. In the last few decades, methodological improvements and fully automated modules have allowed the development of carbon-11 tracers for clinical use. Radiolabeling natural compounds with carbon-11 by substituting one of the backbone carbons with the radionuclide has provided important information on the biochemistry of the authentic compounds and increased the understanding of their in vivo behavior in healthy and diseased states. The number of endogenous and natural compounds essential for human life is staggering, ranging from simple alcohols to vitamins and peptides. This review collates all the carbon-11 radiolabeled endogenous and natural exogenous compounds synthesised to date, including essential information on their radiochemistry methodologies and preclinical and clinical studies in healthy subjects.
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Affiliation(s)
- Antonio Shegani
- School
of Biomedical Engineering & Imaging Sciences, King’s College London, King’s Health Partners, St Thomas’ Hospital, London SE1 7EH, United Kingdom
| | - Steven Kealey
- School
of Biomedical Engineering & Imaging Sciences, King’s College London, King’s Health Partners, St Thomas’ Hospital, London SE1 7EH, United Kingdom
| | - Federico Luzi
- School
of Biomedical Engineering & Imaging Sciences, King’s College London, King’s Health Partners, St Thomas’ Hospital, London SE1 7EH, United Kingdom
| | - Filippo Basagni
- Department
of Pharmacy and Biotechnology, Alma Mater
Studiorum−University of Bologna, via Belmeloro 6, 40126 Bologna, Italy
| | - Joana do Mar Machado
- School
of Biomedical Engineering & Imaging Sciences, King’s College London, King’s Health Partners, St Thomas’ Hospital, London SE1 7EH, United Kingdom
| | - Sevban Doğan Ekici
- School
of Biomedical Engineering & Imaging Sciences, King’s College London, King’s Health Partners, St Thomas’ Hospital, London SE1 7EH, United Kingdom
| | - Alessandra Ferocino
- Institute
of Organic Synthesis and Photoreactivity, Italian National Research Council, via Piero Gobetti 101, 40129 Bologna, Italy
| | - Antony D. Gee
- School
of Biomedical Engineering & Imaging Sciences, King’s College London, King’s Health Partners, St Thomas’ Hospital, London SE1 7EH, United Kingdom,A.G.: email,
| | - Salvatore Bongarzone
- School
of Biomedical Engineering & Imaging Sciences, King’s College London, King’s Health Partners, St Thomas’ Hospital, London SE1 7EH, United Kingdom,S.B.:
email,
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4
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Schmidt KC, Loutaev I, Burlin TV, Thurm A, Sheeler C, Smith CB. Decreased rates of cerebral protein synthesis in conscious young adults with fragile X syndrome demonstrated by L-[1- 11C]leucine PET. J Cereb Blood Flow Metab 2022; 42:1666-1675. [PMID: 35350914 PMCID: PMC9441731 DOI: 10.1177/0271678x221090997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Fragile X syndrome (FXS) is the most common inherited cause of intellectual disability. Fragile X mental retardation protein, a putative translation suppressor, is significantly reduced in FXS. The prevailing hypothesis is that rates of cerebral protein synthesis (rCPS) are increased by the absence of this regulatory protein. We have previously reported increased rCPS in the Fmr1 knockout mouse model of FXS. To address the hypothesis in human subjects, we measured rCPS in young men with FXS with L-[1-11C]leucine PET. In previous studies we had used sedation during imaging, and we did not find increases in rCPS as had been seen in the mouse model. Since mouse measurements were conducted in awake animals, we considered the possibility that sedation may have confounded our results. In the present study we used a modified and validated PET protocol that made it easier for participants with FXS to undergo the study awake. We compared rCPS in 10 fragile X participants and 16 healthy controls all studied while awake. Contrary to the prevailing hypothesis and findings in Fmr1 knockout mice, results indicate that rCPS in awake participants with FXS are decreased in whole brain and most brain regions by 13-21% compared to healthy controls.
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Affiliation(s)
- Kathleen C Schmidt
- Section on Neuroadaptation & Protein Metabolism, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Inna Loutaev
- Section on Neuroadaptation & Protein Metabolism, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Thomas V Burlin
- Section on Neuroadaptation & Protein Metabolism, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Audrey Thurm
- Neurodevelopmental and Behavioral Phenotyping Service, Office of the Clinical Director, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Carrie Sheeler
- Section on Neuroadaptation & Protein Metabolism, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Carolyn Beebe Smith
- Section on Neuroadaptation & Protein Metabolism, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
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Takatani S, Tahara T, Tsuji M, Ozaki D, Shibata N, Hashizume Y, Suzuki M, Onoe H, Watanabe Y, Doi H. Synthesis of L-[5- 11 C]Leucine and L-α-[5- 11 C]Methylleucine via Pd 0 -mediated 11 C-Methylation and Microfluidic Hydrogenation: Potentiality of Leucine PET Probes for Tumor Imaging. ChemMedChem 2021; 16:3271-3279. [PMID: 34128324 DOI: 10.1002/cmdc.202100255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Indexed: 11/06/2022]
Abstract
The efficient synthesis of L-[5-11 C]leucine and L-α-[5-11 C]methylleucine has been investigated using a continuous two-step sequence of rapid reactions consisting of Pd0 -mediated 11 C-methylation and microfluidic hydrogenation. The synthesis of L-[5-11 C]leucine and L-α-[5-11 C]methylleucine was accomplished within 40 min with a decay-corrected radiochemical yield of 15-38 % based on [11 C]CH3 I, radiochemical purity of 95-99 %, and chemical purity of 95-99 %. The Pd impurities in the injectable solution measured using inductively coupled plasma mass spectrometry met the international criteria for human use. Positron emission tomography scanning after an intravenous injection of L-[5-11 C]leucine or L-α-[5-11 C]methyl leucine in A431 tumor-bearing mice was performed. As a result, L-α-[5-11 C]methylleucine was found to be a potentially useful probe for visualizing the tumor. Tissue distribution analysis showed that the accumulation value of L-α-[5-11 C]methylleucine in tumor tissue was high [12±3% injected dose/g tissue (%ID/g)].
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Affiliation(s)
- Shuhei Takatani
- Laboratory for Labeling Chemistry, RIKEN Center for Biosystems Dynamics Research, 6-7-3 Minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo, 650-0047, Japan.,Division of Bio-Function Dynamics Imaging, RIKEN Center for Life Science Technologies, 6-7-3 Minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo, 650-0047, Japan
| | - Tsuyoshi Tahara
- Laboratory for Biofunction Dynamics Imaging, RIKEN Center for Biosystems Dynamics Research, 6-7-3 Minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo, 650-0047, Japan.,Division of Bio-Function Dynamics Imaging, RIKEN Center for Life Science Technologies, 6-7-3 Minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo, 650-0047, Japan
| | - Mieko Tsuji
- Division of Bio-Function Dynamics Imaging, RIKEN Center for Life Science Technologies, 6-7-3 Minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo, 650-0047, Japan
| | - Daiki Ozaki
- Division of Bio-Function Dynamics Imaging, RIKEN Center for Life Science Technologies, 6-7-3 Minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo, 650-0047, Japan
| | - Nina Shibata
- Division of Bio-Function Dynamics Imaging, RIKEN Center for Life Science Technologies, 6-7-3 Minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo, 650-0047, Japan
| | - Yoshinobu Hashizume
- RIKEN Program for Drug Discovery and Medical Technology Platforms, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Masaaki Suzuki
- Division of Bio-Function Dynamics Imaging, RIKEN Center for Life Science Technologies, 6-7-3 Minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo, 650-0047, Japan.,National Center for Geriatrics and Gerontology 35 Gengo, Morioka Obu, Aichi, 474-8511, Japan
| | - Hirotaka Onoe
- Human Brain Research Center, Graduate School of Medicine, Kyoto University, 54 Shogoin-kawahara-cho, Sakyo-ku, Kyoto, 606-8507, (Japan)
| | - Yasuyoshi Watanabe
- Laboratory for Pathophysiological and Health Science, RIKEN Center for Biosystems Dynamics Research, 6-7-3 Minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo, 650-0047, Japan.,Division of Bio-Function Dynamics Imaging, RIKEN Center for Life Science Technologies, 6-7-3 Minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo, 650-0047, Japan
| | - Hisashi Doi
- Laboratory for Labeling Chemistry, RIKEN Center for Biosystems Dynamics Research, 6-7-3 Minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo, 650-0047, Japan.,Division of Bio-Function Dynamics Imaging, RIKEN Center for Life Science Technologies, 6-7-3 Minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo, 650-0047, Japan
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6
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Validation technique and improvements introduced in a new dedicated brain positron emission tomograph (CareMiBrain). Rev Esp Med Nucl Imagen Mol 2021. [PMID: 34059483 DOI: 10.1016/j.remn.2021.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The goal of developing a PET dedicated to the brain (CareMiBrain) has evolved from its initial approach to diagnosis and monitoring of dementias, to the more ambitious of creating a revolutionary clinical pathway for the knowledge and personalized treatment of multiple neurological diseases. The main innovative feature of CareMiBrain is the use of detectors with continuous crystals, which allow a high resolution determination of the depth of annihilation photons interaction within the thickness of the scintillation crystal. The technical validation phase of the equipment consisted of a pilot, prospective and observational study whose objective was to obtain the first images (40 patients), analyze them and make adjustments in the acquisition, reconstruction and correction parameters, comparing the image quality of the CareMiBrain equipment with that of the whole-body PET-CT. Thanks to the team meetings and the joint analysis of the images, it was possible to detect its weak points and some of its causes. The calibration, acquisition and processing processes, as well as the reconstruction, were optimized, the number of iterations was set to achieve the best signal-to-noise ratio, the random correction was optimized and a post-processing algorithm was included in the reconstruction algorithm. The main technical improvements implemented in this phase of technical validation carried out through collaboration of the Services of Nuclear Medicine and Neurology of the Hospital Clínico San Carlos with the Spanish company Oncovision will be exposed in a project financed with funds from the European Union (Horizon 2020 innovation program, 713323).
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7
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Cabrera-Martín MN, González-Pavón G, Sanchís Hernández M, Morera-Ballester C, Matías-Guiu JA, Carreras Delgado JL. Validation technique and improvements introduced in a new dedicated brain positron emission tomograph (CareMiBrain). Rev Esp Med Nucl Imagen Mol 2021; 40:239-248. [PMID: 34218886 DOI: 10.1016/j.remnie.2021.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 04/08/2021] [Indexed: 11/30/2022]
Abstract
The goal of developing a PET dedicated to the brain (CareMiBrain) has evolved from its initial approach to diagnosis and monitoring of dementias, to the more ambitious of creating a revolutionary clinical pathway for the knowledge and personalized treatment of multiple neurological diseases. The main innovative feature of CareMiBrain is the use of detectors with continuous crystals, which allow a high resolution determination of the depth of annihilation photons interaction within the thickness of the scintillation crystal. The technical validation phase of the equipment consisted of a pilot, prospective and observational study whose objective was to obtain the first images (40 patients), analyze them and make adjustments in the acquisition, reconstruction and correction parameters, comparing the image quality of the CareMiBrain equipment with that of the whole-body PET/CT. Thanks to the team meetings and the joint analysis of the images, it was possible to detect its weak points and some of its causes. The calibration, acquisition and processing processes, as well as the reconstruction, were optimized, the number of iterations was set to achieve the best signal-to-noise ratio, the random correction was optimized and a post-processing algorithm was included in the reconstruction algorithm. The main technical improvements implemented in this phase of technical validation carried out through collaboration of the Services of Nuclear Medicine and Neurology of the Hospital Clínico San Carlos with the Spanish company Oncovision will be exposed in a project financed with funds from the European Union (Horizon 2020 innovation program, 713323).
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Affiliation(s)
- María Nieves Cabrera-Martín
- Servicio de Medicina Nuclear, Hospital Clínico San Carlos, Instituto de Investigación Sanitaria San Carlos (IdISSC), Universidad Complutense, Madrid, Spain.
| | | | | | | | - Jordi A Matías-Guiu
- Servicio de Neurología, Hospital Clínico San Carlos, Instituto de Investigación Sanitaria San Carlos (IdISSC), Universidad Complutense, Madrid, Spain
| | - José Luis Carreras Delgado
- Servicio de Medicina Nuclear, Hospital Clínico San Carlos, Instituto de Investigación Sanitaria San Carlos (IdISSC), Universidad Complutense, Madrid, Spain
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Schmidt KC, Loutaev I, Quezado Z, Sheeler C, Smith CB. Regional rates of brain protein synthesis are unaltered in dexmedetomidine sedated young men with fragile X syndrome: A L-[1- 11C]leucine PET study. Neurobiol Dis 2020; 143:104978. [PMID: 32569795 PMCID: PMC7425798 DOI: 10.1016/j.nbd.2020.104978] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 06/01/2020] [Accepted: 06/15/2020] [Indexed: 02/06/2023] Open
Abstract
Fragile X syndrome (FXS) is the most common inherited cause of intellectual disability. Fragile X mental retardation protein (FMRP), a putative translation suppressor, is absent or significantly reduced in FXS. One prevailing hypothesis is that rates of protein synthesis are increased by the absence of this regulatory protein. In accord with this hypothesis, we have previously reported increased rates of cerebral protein synthesis (rCPS) in the Fmr1 knockout mouse model of FXS and others have reported similar effects in hippocampal slices. To address the hypothesis in human subjects, we applied the L[1-11C]leucine PET method to measure rCPS in adults with FXS and healthy controls. All subjects were males between the ages of 18 and 24 years and free of psychotropic medication. As most fragile X participants were not able to undergo the PET study awake, we used dexmedetomidine for sedation during the imaging studies. We found no differences between rCPS measured during dexmedetomidine-sedation and the awake state in ten healthy controls. In the comparison of rCPS in dexmedetomidine-sedated fragile X participants (n = 9) and healthy controls (n = 14) we found no statistically significant differences. Our results from in vivo measurements in human brain do not support the hypothesis that rCPS are elevated due to the absence of FMRP. This hypothesis is based on findings in animal models and in vitro measurements in human peripheral cells. The absence of a translation suppressor may produce a more complex response in pathways regulating translation than previously thought. We may need to revise our working hypotheses regarding FXS and our thinking about potential therapeutics.
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Affiliation(s)
- Kathleen C Schmidt
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, 10 Center Drive, Room 2D54, Bethesda, MD 20892-1298, United States of America
| | - Inna Loutaev
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, 10 Center Drive, Room 2D54, Bethesda, MD 20892-1298, United States of America
| | - Zenaide Quezado
- Department of Perioperative Medicine, Clinical Center, National Institutes of Health, 10 Center Drive, Bethesda, MD 20892-1512, United States of America
| | - Carrie Sheeler
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, 10 Center Drive, Room 2D54, Bethesda, MD 20892-1298, United States of America
| | - Carolyn Beebe Smith
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, 10 Center Drive, Room 2D54, Bethesda, MD 20892-1298, United States of America.
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9
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Tomasi G, Veronese M, Bertoldo A, Smith CB, Schmidt KC. Substitution of venous for arterial blood sampling in the determination of regional rates of cerebral protein synthesis with L-[1- 11C]leucine PET: A validation study. J Cereb Blood Flow Metab 2019; 39:1849-1863. [PMID: 29664322 PMCID: PMC6727135 DOI: 10.1177/0271678x18771242] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
We developed and validated a method to estimate input functions for determination of regional rates of cerebral protein synthesis (rCPS) with L-[1-11C]leucine PET without arterial sampling. The method is based on a population-derived input function (PDIF) approach, with venous samples for calibration. Population input functions were constructed from arterial blood data measured in 25 healthy 18-24-year-old males who underwent L-[1-11C]leucine PET scans while awake. To validate the approach, three additional groups of 18-27-year-old males underwent L-[1-11C]leucine PET scans with both arterial and venous blood sampling: 13 awake healthy volunteers, 10 sedated healthy volunteers, and 5 sedated subjects with fragile X syndrome. Rate constants of the L-[1-11C]leucine kinetic model were estimated voxel-wise with measured arterial input functions and with venous-calibrated PDIFs. Venous plasma leucine measurements were used with venous-calibrated PDIFs for rCPS computation. rCPS determined with PDIFs calibrated with 30-60 min venous samples had small errors (RMSE: 4-9%), and no statistically significant differences were found in any group when compared to rCPS determined with arterial input functions. We conclude that in young adult males, PDIFs calibrated with 30-60 min venous samples can be used in place of arterial input functions for determination of rCPS with L-[1-11C]leucine PET.
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Affiliation(s)
- Giampaolo Tomasi
- Section on Neuroadaptation & Protein
Metabolism, National Institute of Mental Health, Bethesda, MD, USA
| | - Mattia Veronese
- Department of Neuroimaging, IoPPN,
King’s College London, London, UK
| | | | - Carolyn B Smith
- Section on Neuroadaptation & Protein
Metabolism, National Institute of Mental Health, Bethesda, MD, USA
| | - Kathleen C Schmidt
- Section on Neuroadaptation & Protein
Metabolism, National Institute of Mental Health, Bethesda, MD, USA
- Kathleen C Schmidt, Section on
Neuroadaptation & Protein Metabolism, National Institute of Mental Health,
Bldg 10, Room 2D54, 10 Center Drive, Bethesda, MD 20892-1298, USA.
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10
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Catana C. Development of Dedicated Brain PET Imaging Devices: Recent Advances and Future Perspectives. J Nucl Med 2019; 60:1044-1052. [PMID: 31028166 DOI: 10.2967/jnumed.118.217901] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Accepted: 04/16/2019] [Indexed: 12/12/2022] Open
Abstract
Whole-body PET scanners are not optimized for imaging small structures in the human brain. Several PET devices specifically designed for this task have been proposed either for stand-alone operation or as MR-compatible inserts. The main distinctive features of some of the most recent concepts and their performance characteristics, with a focus on spatial resolution and sensitivity, are reviewed. The trade-offs between the various performance characteristics, desired capabilities, and cost that need to be considered when designing a dedicated brain scanner are presented. Finally, the aspirational goals for future-generation scanners, some of the factors that have contributed to the current status, and how recent advances may affect future developments in dedicated brain PET instrumentation are briefly discussed.
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Affiliation(s)
- Ciprian Catana
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts
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11
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Picchioni D, Schmidt KC, McWhirter KK, Loutaev I, Pavletic AJ, Speer AM, Zametkin AJ, Miao N, Bishu S, Turetsky KM, Morrow AS, Nadel JL, Evans BC, Vesselinovitch DM, Sheeler CA, Balkin TJ, Smith CB. Rates of cerebral protein synthesis in primary visual cortex during sleep-dependent memory consolidation, a study in human subjects. Sleep 2018; 41:4996371. [PMID: 29771362 PMCID: PMC6251561 DOI: 10.1093/sleep/zsy088] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 03/01/2018] [Indexed: 11/14/2022] Open
Abstract
If protein synthesis during sleep is required for sleep-dependent memory consolidation, we might expect rates of cerebral protein synthesis (rCPS) to increase during sleep in the local brain circuits that support performance on a particular task following training on that task. To measure circuit-specific brain protein synthesis during a daytime nap opportunity, we used the L-[1-(11)C]leucine positron emission tomography (PET) method with simultaneous polysomnography. We trained subjects on the visual texture discrimination task (TDT). This was followed by a nap opportunity during the PET scan, and we retested them later in the day after the scan. The TDT is considered retinotopically specific, so we hypothesized that higher rCPS in primary visual cortex would be observed in the trained hemisphere compared to the untrained hemisphere in subjects who were randomized to a sleep condition. Our results indicate that the changes in rCPS in primary visual cortex depended on whether subjects were in the wakefulness or sleep condition but were independent of the side of the visual field trained. That is, only in the subjects randomized to sleep, rCPS in the right primary visual cortex was higher than the left regardless of side trained. Other brain regions examined were not so affected. In the subjects who slept, performance on the TDT improved similarly regardless of the side trained. Results indicate a regionally selective and sleep-dependent effect that occurs with improved performance on the TDT.
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Affiliation(s)
- Dante Picchioni
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, Bethesda, MD
- Advanced Magnetic Resonance Imaging Section, National Institute of Neurological Disorders and Stroke, Bethesda, MD
- Behavioral Biology Branch, Walter Reed Army Institute of Research, Silver Spring, MD
| | - Kathleen C Schmidt
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, Bethesda, MD
| | - Kelly K McWhirter
- Behavioral Biology Branch, Walter Reed Army Institute of Research, Silver Spring, MD
| | - Inna Loutaev
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, Bethesda, MD
| | - Adriana J Pavletic
- Office of the Clinical Director, National Institute of Mental Health, Bethesda, MD
| | - Andrew M Speer
- Office of the Clinical Director, National Institute of Mental Health, Bethesda, MD
| | - Alan J Zametkin
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, Bethesda, MD
| | - Ning Miao
- Department of Perioperative Medicine, National Institutes of Health Clinical Center, Bethesda, MD
| | - Shrinivas Bishu
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, Bethesda, MD
| | - Kate M Turetsky
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, Bethesda, MD
| | - Anne S Morrow
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, Bethesda, MD
| | - Jeffrey L Nadel
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, Bethesda, MD
| | - Brittney C Evans
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, Bethesda, MD
| | - Diana M Vesselinovitch
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, Bethesda, MD
| | - Carrie A Sheeler
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, Bethesda, MD
| | - Thomas J Balkin
- Behavioral Biology Branch, Walter Reed Army Institute of Research, Silver Spring, MD
| | - Carolyn B Smith
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, Bethesda, MD
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12
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Tomasi G, Veronese M, Bertoldo A, Beebe Smith C, Schmidt KC. Effects of shortened scanning intervals on calculated regional rates of cerebral protein synthesis determined with the L-[1-11C]leucine PET method. PLoS One 2018; 13:e0195580. [PMID: 29659612 PMCID: PMC5901930 DOI: 10.1371/journal.pone.0195580] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 03/26/2018] [Indexed: 11/19/2022] Open
Abstract
To examine effects of scan duration on estimates of regional rates of cerebral protein synthesis (rCPS), we reanalyzed data from thirty-nine previously reported L-[1-11C]leucine PET studies. Subjects consisted of 12 healthy volunteers studied twice, awake and under propofol sedation, and 15 subjects with fragile X syndrome (FXS) studied once under propofol sedation. All scans were acquired on a high resolution scanner. We used a basis function method for voxelwise estimation of parameters of the kinetic model of L-[1-11C]leucine and rCPS over the interval beginning at the time of tracer injection and ending 30, 45, 60, 75 or 90 min later. For each study and scan interval, regional estimates in nine regions and whole brain were obtained by averaging voxelwise estimates over all voxels in the region. In all three groups rCPS was only slightly affected by scan interval length and was very stable between 60 and 90 min. Furthermore, statistical comparisons of rCPS between awake and sedated healthy volunteers provided almost identical results when they were based on 60 min scan data as when they were based on data from the full 90 min interval. Statistical comparisons between sedated healthy volunteers and sedated subjects with FXS also yielded almost identical results when based on 60 and 90 min scan intervals. We conclude that, under the conditions of our studies, scan duration can be shortened to 60 min without loss of precision.
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Affiliation(s)
- Giampaolo Tomasi
- Section on Neuroadaptation & Protein Metabolism, National Institute of Mental Health, Bethesda, Maryland, United States of America
| | - Mattia Veronese
- Department of Neuroimaging, IoPPN, King’s College London, London, United Kingdom
| | | | - Carolyn Beebe Smith
- Section on Neuroadaptation & Protein Metabolism, National Institute of Mental Health, Bethesda, Maryland, United States of America
| | - Kathleen C. Schmidt
- Section on Neuroadaptation & Protein Metabolism, National Institute of Mental Health, Bethesda, Maryland, United States of America
- * E-mail:
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13
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Veronese M, Bertoldo A, Tomasi G, Smith CB, Schmidt KC. Impact of tissue kinetic heterogeneity on PET quantification: case study with the L-[1- 11C]leucine PET method for cerebral protein synthesis rates. Sci Rep 2018; 8:931. [PMID: 29343731 PMCID: PMC5772379 DOI: 10.1038/s41598-017-18890-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 12/16/2017] [Indexed: 11/09/2022] Open
Abstract
Functional quantification with PET is generally based on modeling that assumes tissue regions are kinetically homogeneous. Even in regions sufficiently small to approach homogeneity, spillover due to resolution limitations of PET scanners may introduce heterogeneous kinetics into measured data. Herein we consider effects of kinetic heterogeneity at the smallest volume accessible, the single image voxel. We used L-[1-11C]leucine PET and compared rates of cerebral protein synthesis (rCPS) estimated voxelwise with methods that do (Spectral Analysis Iterative Filter, SAIF) and do not (Basis Function Method, BFM) allow for kinetic heterogeneity. In high resolution PET data with good counting statistics BFM produced estimates of rCPS comparable to SAIF, but at lower computational cost; thus the simpler, less costly method can be applied. With poorer counting statistics (lower injected radiotracer doses), BFM estimates were more biased. In data smoothed to simulate lower resolution PET, BFM produced estimates of rCPS 9-14% higher than SAIF, overestimation consistent with applying a homogeneous tissue model to kinetically heterogeneous data. Hence with lower resolution data it is necessary to account for kinetic heterogeneity in the analysis. Kinetic heterogeneity may impact analyses of other tracers and scanning protocols differently; assessments should be made on a case by case basis.
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Affiliation(s)
- Mattia Veronese
- Section on Neuroadaptation & Protein Metabolism, National Institute of Mental Health, Bethesda, Maryland, USA.,Department of Neuroimaging, IoPPN, King's college London, London, UK
| | - Alessandra Bertoldo
- Department of Information Engineering, University of Padova, Padova, Italy.,Padua Neuroscience Center, University of Padova, Padova, Italy
| | - Giampaolo Tomasi
- Section on Neuroadaptation & Protein Metabolism, National Institute of Mental Health, Bethesda, Maryland, USA
| | - Carolyn Beebe Smith
- Section on Neuroadaptation & Protein Metabolism, National Institute of Mental Health, Bethesda, Maryland, USA
| | - Kathleen C Schmidt
- Section on Neuroadaptation & Protein Metabolism, National Institute of Mental Health, Bethesda, Maryland, USA.
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14
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Zlatopolskiy BD, Zischler J, Schäfer D, Urusova EA, Guliyev M, Bannykh O, Endepols H, Neumaier B. Discovery of 7-[18F]Fluorotryptophan as a Novel Positron Emission Tomography (PET) Probe for the Visualization of Tryptophan Metabolism in Vivo. J Med Chem 2017; 61:189-206. [DOI: 10.1021/acs.jmedchem.7b01245] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Boris D. Zlatopolskiy
- Institute
of Neuroscience and Medicine, INM-5: Nuclear Chemistry, Forschungszentrum Jülich GmbH, Jülich 52428, Germany
- Institute
of Radiochemistry and Experimental Molecular Imaging, University Clinic Cologne, Cologne 50937, Germany
- Max Planck Institute for Metabolism Research, Cologne 50931, Germany
| | - Johannes Zischler
- Institute
of Neuroscience and Medicine, INM-5: Nuclear Chemistry, Forschungszentrum Jülich GmbH, Jülich 52428, Germany
- Institute
of Radiochemistry and Experimental Molecular Imaging, University Clinic Cologne, Cologne 50937, Germany
| | - Dominique Schäfer
- Institute
of Neuroscience and Medicine, INM-5: Nuclear Chemistry, Forschungszentrum Jülich GmbH, Jülich 52428, Germany
| | - Elizaveta A. Urusova
- Institute
of Neuroscience and Medicine, INM-5: Nuclear Chemistry, Forschungszentrum Jülich GmbH, Jülich 52428, Germany
- Institute
of Radiochemistry and Experimental Molecular Imaging, University Clinic Cologne, Cologne 50937, Germany
- Max Planck Institute for Metabolism Research, Cologne 50931, Germany
| | - Mehrab Guliyev
- Institute
of Neuroscience and Medicine, INM-5: Nuclear Chemistry, Forschungszentrum Jülich GmbH, Jülich 52428, Germany
- Institute
of Radiochemistry and Experimental Molecular Imaging, University Clinic Cologne, Cologne 50937, Germany
| | - Olesia Bannykh
- Institute
of Neuroscience and Medicine, INM-5: Nuclear Chemistry, Forschungszentrum Jülich GmbH, Jülich 52428, Germany
- Institute
of Radiochemistry and Experimental Molecular Imaging, University Clinic Cologne, Cologne 50937, Germany
| | - Heike Endepols
- Institute
of Neuroscience and Medicine, INM-5: Nuclear Chemistry, Forschungszentrum Jülich GmbH, Jülich 52428, Germany
- Institute
of Radiochemistry and Experimental Molecular Imaging, University Clinic Cologne, Cologne 50937, Germany
- Max Planck Institute for Metabolism Research, Cologne 50931, Germany
- Department
of Nuclear Medicine, University Clinic Cologne, Cologne 50937, Germany
| | - Bernd Neumaier
- Institute
of Neuroscience and Medicine, INM-5: Nuclear Chemistry, Forschungszentrum Jülich GmbH, Jülich 52428, Germany
- Institute
of Radiochemistry and Experimental Molecular Imaging, University Clinic Cologne, Cologne 50937, Germany
- Max Planck Institute for Metabolism Research, Cologne 50931, Germany
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15
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Hellyer PJ, Barry EF, Pellizzon A, Veronese M, Rizzo G, Tonietto M, Schütze M, Brammer M, Aurélio Romano-Silva M, Bertoldo A, Turkheimer FE. Protein synthesis is associated with high-speed dynamics and broad-band stability of functional hubs in the brain. Neuroimage 2017; 155:209-216. [PMID: 28465163 PMCID: PMC5519503 DOI: 10.1016/j.neuroimage.2017.04.062] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 04/10/2017] [Accepted: 04/26/2017] [Indexed: 01/30/2023] Open
Abstract
L-[1-11C]leucine PET can be used to measure in vivo protein synthesis in the brain. However, the relationship between regional protein synthesis and on-going neural dynamics is unclear. We use a graph theoretical approach to examine the relationship between cerebral protein synthesis (rCPS) and both static and dynamical measures of functional connectivity (measured using resting state functional MRI, R-fMRI). Our graph theoretical analysis demonstrates a significant positive relationship between protein turnover and static measures of functional connectivity. We compared these results to simple measures of metabolism in the cortex using [18F]FDG PET). Whilst some relationships between [18F]FDG binding and graph theoretical measures was present, there remained a significant relationship between protein turnover and graph theoretical measures, which were more robustly explained by L-[1-11C]Leucine than [18F]FDG PET. This relationship was stronger in dynamics at a faster temporal resolution relative to dynamics measured over a longer epoch. Using a Dynamic connectivity approach, we also demonstrate that broad-band dynamic measures of Functional Connectivity (FC), are inversely correlated with protein turnover, suggesting greater stability of FC in highly interconnected hub regions is supported by protein synthesis. Overall, we demonstrate that cerebral protein synthesis has a strong relationship independent of tissue metabolism to neural dynamics at the macroscopic scale. Spontaneous, neural dynamics are fundamental for information processing & function We combine L-[1-11C]leucine PET with Static and Dynamic measures of network topology ‘Hub’ brain regions are linked to increased protein synthesis, independent of tissue metabolism Stability of network hubs is inversely correlated with protein turnover Strong, stable hubs are supported by protein synthesis
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Affiliation(s)
- Peter J Hellyer
- Centre for Neuroimaging Sciences, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK; Department of Bioengineering, Imperial College London, Royal School of Mines, Room 4.35, South Kensington Campus, SW7 2AZ, UK
| | - Erica F Barry
- Centre for Neuroimaging Sciences, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Alberto Pellizzon
- Department of Information Engineering, University of Padova, Padova, Italy
| | - Mattia Veronese
- Centre for Neuroimaging Sciences, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Gaia Rizzo
- Department of Information Engineering, University of Padova, Padova, Italy
| | - Matteo Tonietto
- Department of Information Engineering, University of Padova, Padova, Italy
| | - Manuel Schütze
- Instituto Nacional de Ciência e Tecnologia em Medicina Molecular, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Michael Brammer
- Centre for Neuroimaging Sciences, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK; Instituto Nacional de Ciência e Tecnologia em Medicina Molecular, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Marco Aurélio Romano-Silva
- Instituto Nacional de Ciência e Tecnologia em Medicina Molecular, Federal University of Minas Gerais, Belo Horizonte, Brazil; Mental Health Department, Faculty of Medicine, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | | | - Federico E Turkheimer
- Centre for Neuroimaging Sciences, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK.
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16
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Castellaro M, Rizzo G, Tonietto M, Veronese M, Turkheimer FE, Chappell MA, Bertoldo A. A Variational Bayesian inference method for parametric imaging of PET data. Neuroimage 2017; 150:136-149. [PMID: 28213113 DOI: 10.1016/j.neuroimage.2017.02.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 01/22/2017] [Accepted: 02/04/2017] [Indexed: 12/15/2022] Open
Abstract
In dynamic Positron Emission Tomography (PET) studies, compartmental models provide the richest information on the tracer kinetics of the tissue. Inverting such models at the voxel level is however quite challenging due to the low signal-to-noise ratio of the time activity curves. In this study, we propose the use of a Variational Bayesian (VB) approach to efficiently solve this issue and thus obtain robust quantitative parametric maps. VB was adapted to the non-uniform noise distribution of PET data. Moreover, we propose a novel hierarchical scheme to define the model parameter priors directly from the images in case such information are not available from the literature, as often happens with new PET tracers. VB was initially tested on synthetic data generated using compartmental models of increasing complexity, providing accurate (%bias<2%±2%, root mean square error<15%±5%) parameter estimates. When applied to real data on a paradigmatic set of PET tracers (L-[1-11C]leucine, [11C]WAY100635 and [18F]FDG), VB was able to generate reliable parametric maps even in presence of high noise in the data (unreliable estimates<11%±5%).
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Affiliation(s)
- M Castellaro
- Department of Information Engineering, University of Padova, Italy
| | - G Rizzo
- Department of Information Engineering, University of Padova, Italy
| | - M Tonietto
- Department of Information Engineering, University of Padova, Italy
| | - M Veronese
- Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - F E Turkheimer
- Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - M A Chappell
- Institute of Biomedical Engineering, University of Oxford, Old Road Campus Research Building, Old Road Campus, Headington, Oxford, United Kingdom
| | - A Bertoldo
- Department of Information Engineering, University of Padova, Italy.
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17
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Milicevic Sephton S, Aigbirhio FI. Radiosynthesis of Carbon-11 Labeled Puromycin as a Potential PET Candidate for Imaging Protein Synthesis in Vivo. ACS Med Chem Lett 2016; 7:647-51. [PMID: 27326342 PMCID: PMC4904265 DOI: 10.1021/acsmedchemlett.6b00093] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 04/12/2016] [Indexed: 11/28/2022] Open
Abstract
In order to address the limitations associated with the present range of PET radiotracers used for imaging protein synthesis in vivo we have synthesized a candidate PET radiotracer based on Puromycin (3, PURO), a protein synthesis inhibitor. The desmethylPURO 9 precursor for radiolabeling with carbon-11 radioisotope was synthesized in two steps employing EDC/HOBt amide coupling in overall 76% yield. Optimal conditions for radiolabeling were then established via methylation/deprotection sequence. Under these conditions as determined by NMR analysis 9 showed partial stability (ca. 80%) under acidic conditions. Limited evidence of stereochemical stability of 3 was also found. The radiolabeling of intermediate [(11)C]12 was accomplished with up to 57% conversion from [(11)C]iodomethane. An automated method was then developed for high radioactivity radiosynthesis to produce [(11)C]3 ([(11)C]PURO) in 16 ± 6% (n = 3) decay corrected radiochemical yields.
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Affiliation(s)
- Selena Milicevic Sephton
- Molecular Imaging Chemistry
Laboratory, Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, Box 65, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0QQ, U.K.
| | - Franklin I. Aigbirhio
- Molecular Imaging Chemistry
Laboratory, Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, Box 65, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0QQ, U.K.
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18
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FDG-PET Contributions to the Pathophysiology of Memory Impairment. Neuropsychol Rev 2015; 25:326-55. [PMID: 26319237 DOI: 10.1007/s11065-015-9297-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 08/04/2015] [Indexed: 10/23/2022]
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19
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de Esch CE, Zeidler S, Willemsen R. Translational endpoints in fragile X syndrome. Neurosci Biobehav Rev 2014; 46 Pt 2:256-69. [DOI: 10.1016/j.neubiorev.2013.10.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 10/07/2013] [Accepted: 10/09/2013] [Indexed: 01/01/2023]
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20
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Picchioni D, Reith RM, Nadel JL, Smith CB. Sleep, plasticity and the pathophysiology of neurodevelopmental disorders: the potential roles of protein synthesis and other cellular processes. Brain Sci 2014; 4:150-201. [PMID: 24839550 PMCID: PMC4020186 DOI: 10.3390/brainsci4010150] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 02/26/2014] [Accepted: 03/07/2014] [Indexed: 12/28/2022] Open
Abstract
Sleep is important for neural plasticity, and plasticity underlies sleep-dependent memory consolidation. It is widely appreciated that protein synthesis plays an essential role in neural plasticity. Studies of sleep-dependent memory and sleep-dependent plasticity have begun to examine alterations in these functions in populations with neurological and psychiatric disorders. Such an approach acknowledges that disordered sleep may have functional consequences during wakefulness. Although neurodevelopmental disorders are not considered to be sleep disorders per se, recent data has revealed that sleep abnormalities are among the most prevalent and common symptoms and may contribute to the progression of these disorders. The main goal of this review is to highlight the role of disordered sleep in the pathology of neurodevelopmental disorders and to examine some potential mechanisms by which sleep-dependent plasticity may be altered. We will also briefly attempt to extend the same logic to the other end of the developmental spectrum and describe a potential role of disordered sleep in the pathology of neurodegenerative diseases. We conclude by discussing ongoing studies that might provide a more integrative approach to the study of sleep, plasticity, and neurodevelopmental disorders.
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Affiliation(s)
- Dante Picchioni
- Behavioral Biology Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA; E-Mail:
- Advanced MRI Section, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, Bethesda, MD 20892, USA; E-Mails: (R.M.R.); (J.L.N.)
| | - R. Michelle Reith
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, Bethesda, MD 20892, USA; E-Mails: (R.M.R.); (J.L.N.)
| | - Jeffrey L. Nadel
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, Bethesda, MD 20892, USA; E-Mails: (R.M.R.); (J.L.N.)
| | - Carolyn B. Smith
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, Bethesda, MD 20892, USA; E-Mails: (R.M.R.); (J.L.N.)
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21
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Altered cerebral protein synthesis in fragile X syndrome: studies in human subjects and knockout mice. J Cereb Blood Flow Metab 2013; 33:499-507. [PMID: 23299245 PMCID: PMC3618394 DOI: 10.1038/jcbfm.2012.205] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Dysregulated protein synthesis is thought to be a core phenotype of fragile X syndrome (FXS). In a mouse model (Fmr1 knockout (KO)) of FXS, rates of cerebral protein synthesis (rCPS) are increased in selective brain regions. We hypothesized that rCPS are also increased in FXS subjects. We measured rCPS with the L-[1-(11)C]leucine positron emission tomography (PET) method in whole brain and 10 regions in 15 FXS subjects who, because of their impairments, were studied under deep sedation with propofol. We compared results with those of 12 age-matched controls studied both awake and sedated. In controls, we found no differences in rCPS between awake and propofol sedation. Contrary to our hypothesis, FXS subjects under propofol sedation had reduced rCPS in whole brain, cerebellum, and cortex compared with sedated controls. To investigate whether propofol could have a disparate effect in FXS subjects masking usually elevated rCPS, we measured rCPS in C57Bl/6 wild-type (WT) and KO mice awake or under propofol sedation. Propofol decreased rCPS substantially in most regions examined in KO mice, but in WT mice caused few discrete changes. Propofol acts by decreasing neuronal activity either directly or by increasing inhibitory synaptic activity. Our results suggest that changes in synaptic signaling can correct increased rCPS in FXS.
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22
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Rizzo G, Turkheimer FE, Bertoldo A. Multi-scale hierarchical approach for parametric mapping: Assessment on multi-compartmental models. Neuroimage 2013; 67:344-53. [DOI: 10.1016/j.neuroimage.2012.11.045] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Revised: 10/03/2012] [Accepted: 11/19/2012] [Indexed: 11/28/2022] Open
Affiliation(s)
- G Rizzo
- Department of Information Engineering, University of Padova, via Gradenigo 6/b, 35131, Padova, Italy
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23
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Use of spectral analysis with iterative filter for voxelwise determination of regional rates of cerebral protein synthesis with L-[1-11C]leucine PET. J Cereb Blood Flow Metab 2012; 32:1073-85. [PMID: 22395209 PMCID: PMC3367224 DOI: 10.1038/jcbfm.2012.27] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A spectral analysis approach was used to estimate kinetic parameters of the L-[1-(11)C]leucine positron emission tomography (PET) method and regional rates of cerebral protein synthesis (rCPS) on a voxel-by-voxel basis. Spectral analysis applies to both heterogeneous and homogeneous tissues; it does not require prior assumptions concerning number of tissue compartments. Parameters estimated with spectral analysis can be strongly affected by noise, but numerical filters improve estimation performance. Spectral analysis with iterative filter (SAIF) was originally developed to improve estimation of leucine kinetic parameters and rCPS in region-of-interest (ROI) data analyses. In the present study, we optimized SAIF for application at the voxel level. In measured L-[1-(11)C]leucine PET data, voxel-level SAIF parameter estimates averaged over all voxels within a ROI (mean voxel-SAIF) generally agreed well with corresponding estimates derived by applying the originally developed SAIF to ROI time-activity curves (ROI-SAIF). Region-of-interest-SAIF and mean voxel-SAIF estimates of rCPS were highly correlated. Simulations showed that mean voxel-SAIF rCPS estimates were less biased and less variable than ROI-SAIF estimates in the whole brain and cortex; biases were similar in white matter. We conclude that estimation of rCPS with SAIF is improved when the method is applied at voxel level than in ROI analysis.
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24
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Bhakar AL, Dölen G, Bear MF. The pathophysiology of fragile X (and what it teaches us about synapses). Annu Rev Neurosci 2012; 35:417-43. [PMID: 22483044 DOI: 10.1146/annurev-neuro-060909-153138] [Citation(s) in RCA: 275] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Fragile X is the most common known inherited cause of intellectual disability and autism, and it typically results from transcriptional silencing of FMR1 and loss of the encoded protein, FMRP (fragile X mental retardation protein). FMRP is an mRNA-binding protein that functions at many synapses to inhibit local translation stimulated by metabotropic glutamate receptors (mGluRs) 1 and 5. Recent studies on the biology of FMRP and the signaling pathways downstream of mGluR1/5 have yielded deeper insight into how synaptic protein synthesis and plasticity are regulated by experience. This new knowledge has also suggested ways that altered signaling and synaptic function can be corrected in fragile X, and human clinical trials based on this information are under way.
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Affiliation(s)
- Asha L Bhakar
- Howard Hughes Medical Institute, Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
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25
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The Assay of Enzyme Activity by Positron Emission Tomography. MOLECULAR IMAGING IN THE CLINICAL NEUROSCIENCES 2012. [DOI: 10.1007/7657_2012_53] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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26
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Shandal V, Sundaram SK, Chugani DC, Kumar A, Behen ME, Chugani HT. Abnormal brain protein synthesis in language areas of children with pervasive developmental disorder: a L-[1-11C]-leucine PET study. J Child Neurol 2011; 26:1347-54. [PMID: 21636781 DOI: 10.1177/0883073811405200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This study was performed to evaluate the cerebral protein synthesis rate of language brain regions in children with developmental delay with and without pervasive developmental disorder. The authors performed L-[1-(11)C]-leucine positron emission tomography (PET) on 8 developmental delay children with pervasive developmental disorder (mean age, 76.25 months) and 8 developmental delay children without pervasive developmental disorder (mean age, 77.63 months). They found a higher protein synthesis rate in developmental delay children with pervasive developmental disorder in the left posterior middle temporal region (P = .014). There was a significant correlation of the Gilliam Autism Rating Scale autism index score with the protein synthesis rate of the left posterior middle temporal region (r = .496, P = .05). In addition, significant asymmetric protein synthesis (right > left) was observed in developmental delay children without pervasive developmental disorder in the middle frontal and posterior middle temporal regions (P = .03 and P = .04, respectively). In conclusion, abnormal language area protein synthesis in developmentally delayed children may be related to pervasive symptoms.
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Affiliation(s)
- Varun Shandal
- Department of Pediatrics, Wayne State University School of Medicine, Detroit, Michigan, USA
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27
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Alkonyi B, Chugani HT, Muzik O, Chugani DC, Sundaram SK, Kupsky WJ, Batista CE, Juhász C. Increased L-[1-11 C] leucine uptake in the leptomeningeal angioma of sturge-weber syndrome: a PET study. J Neuroimaging 2011; 22:177-83. [PMID: 21223431 DOI: 10.1111/j.1552-6569.2010.00565.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSE We used L-[1-(11) C]leucine (LEU) positron emission tomography (PET) to measure amino acid uptake in children with Sturge-Weber syndrome (SWS), and to relate amino acid uptake measures with glucose metabolism. METHODS LEU and 2-deoxy-2[(18) F]fluoro-D-glucose (FDG) PET were performed in 7 children (age: 5 months-13 years) with unilateral SWS. Asymmetries of LEU uptake in the posterior brain region, underlying the angioma and in frontal cortex, were measured and correlated with glucose hypometabolism. Kinetic analysis of LEU uptake was performed in 4 patients. RESULTS Increased LEU standard uptake value (SUV, mean: 15.1%) was found in the angioma region in 6 patients, and smaller increases in LEU SUV (11.5%) were seen in frontal cortex in 4 of the 6 patients, despite normal glucose metabolism in frontal regions. High LEU SUV was due to both increased tracer transport (3/4 patients) and high protein synthesis rates (2/4). FDG SUV asymmetries in the angioma region were inversely related to LEU SUV asymmetries (r=-.83, P= .042). CONCLUSIONS Increased amino acid uptake in the angioma region and also in less affected frontal regions may provide a marker of pathological mechanisms contributing to chronic brain damage in children with SWS.
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Affiliation(s)
- Bálint Alkonyi
- Carman and Ann Adams Department of Pediatrics, Children's Hospital of Michigan, Wayne State University School of Medicine, Detroit, MI, USA
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Veronese M, Bertoldo A, Bishu S, Unterman A, Tomasi G, Smith CB, Schmidt KC. A spectral analysis approach for determination of regional rates of cerebral protein synthesis with the L-[1-(11)C]leucine PET method. J Cereb Blood Flow Metab 2010; 30:1460-76. [PMID: 20197782 PMCID: PMC2907431 DOI: 10.1038/jcbfm.2010.26] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A spectral analysis approach was used to estimate kinetic model parameters of the L-[1-(11)C]leucine positron emission tomography (PET) method and regional rates of cerebral protein synthesis (rCPS) in predefined regions of interest (ROIs). Unlike analyses based on the assumption that tissue ROIs are kinetically homogeneous, spectral analysis allows for heterogeneity within a region. To improve estimation performance, a new approach was developed-spectral analysis with iterative filter (SAIF). In simulation SAIF produced low bias, low variance estimates of the influx rate constant for leucine (K(1)), blood volume fraction (V(b)), fraction of unlabeled leucine in the tissue precursor pool for protein synthesis derived from arterial plasma (lambda), and rCPS. Simulation of normal count rate studies showed that SAIF applied to ROI time-activity curves (TACs) performed comparably to the basis function method (BFM) applied to voxel TACs when voxelwise estimates were averaged over all voxels in the ROI. At low count rates, however, SAIF performed better. In measured L-[1-(11)C]leucine PET data, there was good agreement between ROI-based SAIF estimates and average voxelwise BFM estimates of K(1), V(b), lambda, and rCPS. We conclude that SAIF sufficiently addresses the problem of tissue heterogeneity in ROI data and provides a valid tool for estimation of rCPS, even in low count rate studies.
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Affiliation(s)
- Mattia Veronese
- Department of Information Engineering, University of Padova, Padova, Italy
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Dölen G, Carpenter RL, Ocain TD, Bear MF. Mechanism-based approaches to treating fragile X. Pharmacol Ther 2010; 127:78-93. [DOI: 10.1016/j.pharmthera.2010.02.008] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Accepted: 02/26/2010] [Indexed: 11/17/2022]
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Voxel-based estimation of kinetic model parameters of the L-[1-(11)C]leucine PET method for determination of regional rates of cerebral protein synthesis: validation and comparison with region-of-interest-based methods. J Cereb Blood Flow Metab 2009; 29:1317-31. [PMID: 19436319 PMCID: PMC2818563 DOI: 10.1038/jcbfm.2009.52] [Citation(s) in RCA: 24] [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 adapted and validated a basis function method (BFM) to estimate at the voxel level parameters of the kinetic model of the L-[1-(11)C]leucine positron emission tomography (PET) method and regional rates of cerebral protein synthesis (rCPS). In simulation at noise levels typical of voxel data, BFM yielded low-bias estimates of rCPS; in measured data, BFM and nonlinear least-squares parameter estimates were in good agreement. We also examined whether there are advantages to using voxel-level estimates averaged over regions of interest (ROIs) in place of estimates obtained by directly fitting ROI time-activity curves (TACs). In both simulated and measured data, fits of ROI TACs were poor, likely because of tissue heterogeneity not taken into account in the kinetic model. In simulation, rCPS determined from fitting ROI TACs was substantially overestimated and BFM-estimated rCPS averaged over all voxels in an ROI was slightly underestimated. In measured data, rCPS determined by regional averaging of voxel estimates was lower than rCPS determined from ROI TACs, consistent with simulation. In both simulated and measured data, intersubject variability of BFM-estimated rCPS averaged over all voxels in a ROI was low. We conclude that voxelwise estimation is preferable to fitting ROI TACs using a homogeneous tissue model.
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Bishu S, Schmidt KC, Burlin TV, Channing MA, Horowitz L, Huang T, Liu ZH, Qin M, Vuong BK, Unterman AJ, Xia Z, Zametkin A, Herscovitch P, Quezado Z, Smith CB. Propofol anesthesia does not alter regional rates of cerebral protein synthesis measured with L-[1-(11)C]leucine and PET in healthy male subjects. J Cereb Blood Flow Metab 2009; 29:1035-47. [PMID: 19223912 PMCID: PMC3150740 DOI: 10.1038/jcbfm.2009.7] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We report regional rates of cerebral protein synthesis (rCPS) in 10 healthy young males, each studied under two conditions: awake and anesthetized with propofol. We used the quantitative L-[1-(11)C]leucine positron emission tomography (PET) method to measure rCPS. The method accounts for the fraction (lambda) of unlabeled leucine in the precursor pool for protein synthesis that is derived from arterial plasma; the remainder comes from proteolysis of tissue proteins. Across 18 regions and whole brain, mean differences in rCPS between studies ranged from -5% to 5% and were within the variability of rCPS in awake studies (coefficient of variation range: 7% to 14%). Similarly, differences in lambda (range: 1% to 4%) were typically within the variability of lambda (coefficient of variation range: 3% to 6%). Intersubject variances and patterns of regional variation were also similar under both conditions. In propofol-anesthetized subjects, rCPS varied regionally from 0.98+/-0.12 to 2.39+/-0.23 nmol g(-1) min(-1) in the corona radiata and in the cerebellum, respectively. Our data indicate that the values, variances, and patterns of regional variation in rCPS and lambda measured by the L-[1-(11)C]leucine PET method are not significantly altered by anesthesia with propofol.
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Affiliation(s)
- Shrinivas Bishu
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, Bethesda, Maryland 20892-1298, USA.
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Dupont P, Warwick J. Kinetic modelling in small animal imaging with PET. Methods 2009; 48:98-103. [PMID: 19318124 DOI: 10.1016/j.ymeth.2009.03.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2009] [Accepted: 03/11/2009] [Indexed: 10/21/2022] Open
Abstract
Small animal imaging with positron emission tomography has undergone a major evolution. This has been driven by technical improvements and the development of dedicated PET camera's for small animals. The focus has shifted from detection of tracer uptake and visualization of the tracer distribution towards the quantification of the physiological parameters necessary to use this technique for kinetic modelling of tracers. At the moment there are still several issues which need further research and evaluation before we can fully employ the possibilities of PET as an in-vivo measurement of underlying molecular biology. These issues relate to improved quantification of measurements, improved image reconstruction and processing, and the use of blood plasma data in combination with kinetic models. Besides the more technical issues, there are two more issues which need further clarification: the effect of the anaesthesia, and the effect of radiation on the experiment itself. In this review, we will give an overview of how the technique can be used but we will also discuss the issues mentioned above. The focus will be on the three major parts of the imaging procedure: acquisition, reconstruction of images, and kinetic modelling of the data.
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Affiliation(s)
- Patrick Dupont
- Laboratory for Cognitive Neurology, KU Leuven, O&N II, Herestraat 49, Bus 1022, 3000 Leuven, Belgium.
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