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Sumi K, Yamazaki K, Nishii R, Sakuda M, Nakamura K, Ashida K, Tamura K, Higashi T. Unique advantages of dynamic l-[11C]methionine PET/CT for assessing the rate of skeletal muscle protein synthesis: A pilot trial in young men. PLoS One 2024; 19:e0305620. [PMID: 39078822 PMCID: PMC11288433 DOI: 10.1371/journal.pone.0305620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Accepted: 06/03/2024] [Indexed: 08/02/2024] Open
Abstract
Although the standard method to evaluate skeletal muscle protein synthesis (MPS) is muscle biopsy, the method is invasive and problematic for multisite use. We conducted a small pilot study in volunteers to investigate changes in MPS according to skeletal muscle site using a noninvasive method in which 6 healthy young men were given yogurt (containing 20 g milk protein) or water, and 1 h later, l-[11C]methionine ([11C]Met) was administered intravenously. Dynamic PET/CT imaging of their thighs was performed for 60 min. The influx constant Ki of [11C]Met in skeletal muscle protein was calculated as an index of MPS using a Patlak plot, and found to be 0.6%-28% higher after ingesting yogurt than after water in 5 of the 6 volunteer participants, but it was 34% lower in the remaining participant. Overall, this indicated no significant increase in Ki after ingesting milk protein. However, when the quadriceps and hamstring muscles were analyzed separately, we found a significant difference in Ki. This demonstrates the potential of visualizing MPS by calculating the Ki for each voxel and reconstructing it as an image, which presents unique advantages of [11C]Met PET/CT for evaluating MPS, such as site-specificity and visualization.
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Affiliation(s)
- Koichiro Sumi
- R&D Division, Meiji Co., Ltd., Hachiouji, Tokyo, Japan
| | - Kana Yamazaki
- Department of Molecular Imaging and Theranostics, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Inage, Chiba, Japan
| | - Ryuichi Nishii
- Department of Molecular Imaging and Theranostics, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Inage, Chiba, Japan
- Biomedical Imaging Sciences, Department of Integrated Health Sciences, Nagoya University Graduate School of Medicine, Tokai National Education and Research System, Higashi-ku, Nagoya, Japan
| | - Misato Sakuda
- R&D Division, Meiji Co., Ltd., Hachiouji, Tokyo, Japan
| | | | - Kinya Ashida
- R&D Division, Meiji Co., Ltd., Hachiouji, Tokyo, Japan
| | - Kentaro Tamura
- Department of Molecular Imaging and Theranostics, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Inage, Chiba, Japan
| | - Tatsuya Higashi
- Department of Molecular Imaging and Theranostics, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Inage, Chiba, Japan
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Li J, Ni B, Yu X, Wang C, Li L, Zhou Y, Gu Y, Huang G, Hou J, Liu J, Chen Y. Metabolic kinetic modeling of [ 11C]methionine based on total-body PET in multiple myeloma. Eur J Nucl Med Mol Imaging 2023; 50:2683-2691. [PMID: 37039900 DOI: 10.1007/s00259-023-06219-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 04/02/2023] [Indexed: 04/12/2023]
Abstract
PURPOSE Multiple myeloma (MM) is a malignant disease characterized by the secretion of monoclonal immunoglobulins and has a high demand for amino acids. [11C]methionine total-body PET is capable of noninvasive dynamic monitoring of radiotracer in vivo, thus providing a way to reveal the dynamic changes of myeloma metabolism. This study aims to analyze the metabolic process of [11C]methionine based on kinetic modeling, and to preliminary reveal its application value in MM. METHODS Dynamic total-body [11C]methionine PET/CT was conducted with uEXPLORER in 12 subjects (9 MM patients and 3 controls). The tissue time activity curves (TACs) of organs and bone marrows were extracted. Model fitting of TACs was operated using PMOD Kinetic Modeling. After validation by Goodness of fit (GOF), the reversible two-tissue compartment model (2T4k) was used to further analysis. R software was used to analyze the correlation between kinetic parameters and clinical indicators. RESULTS The 2T4k has passed the criterion of GOF and was used to fit the data of 0-20 minutes. The [11C]methionine net uptake rate (Ki) was significantly higher in the MM lesions than in the non-myeloma controls (control: 0.040±0.007 mL/g/min, MM: 0.171±0.108 mL/g/min, p=0.009). The Ki values were found to be correlated with M protein levels in MM patients. MM patients with t(4;14) translocations had an elevated k4 value compared with t(4;14) negative patients. CONCLUSION MM lesions have a propensity for uptake of [11C]methionine. The serum levels of M protein are correlated with [11C]methionine uptake rate in myeloma. Metabolic classification based on the k4 value may be a promising strategy for risk stratification in MM.
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Affiliation(s)
- Jiajin Li
- Department of Nuclear Medicine, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China
| | - Beiwen Ni
- Department of Hematology, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China
| | - Xiaofeng Yu
- Department of Nuclear Medicine, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China
| | - Cheng Wang
- Department of Nuclear Medicine, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China
| | - Lianghua Li
- Department of Nuclear Medicine, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China
| | - Yun Zhou
- Central Research Institute, United Imaging Healthcare Group Co., Ltd, Shanghai, 200032, China
| | - Yue Gu
- Central Research Institute, United Imaging Healthcare Group Co., Ltd, Shanghai, 200032, China
| | - Gang Huang
- Department of Nuclear Medicine, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China
- Shanghai Key Laboratory of Molecular Imaging, Shanghai University of Medicine and Health Sciences, Shanghai, 201318, China
| | - Jian Hou
- Department of Hematology, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China.
| | - Jianjun Liu
- Department of Nuclear Medicine, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China.
| | - Yumei Chen
- Department of Nuclear Medicine, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China.
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Serum Metabolites Associated with Muscle Hypertrophy after 8 Weeks of High- and Low-Load Resistance Training. Metabolites 2023; 13:metabo13030335. [PMID: 36984775 PMCID: PMC10058868 DOI: 10.3390/metabo13030335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 02/13/2023] [Accepted: 02/18/2023] [Indexed: 02/26/2023] Open
Abstract
The mechanisms responsible for the similar muscle growth attained with high- and low-load resistance training (RT) have not yet been fully elucidated. One mechanism is related to the mechanical stimulus and the level of motor unit recruitment; another mechanism is related to the metabolic response. We investigated the electromyographic signal amplitude (sEMG) and the general metabolic response to high-load RT (HL) and low-load resistance training (LL). We measured muscle thickness by ultrasound, sEMG amplitude by electromyography, and analysis of metabolites expressed through metabolomics. No differences were observed between the HL and LL groups for metabolic response and muscle thickness. A greater amplitude of sEMG was observed in the HL group. In addition, a correlation was observed between changes in muscle thickness of the vastus lateralis muscle in the HL group and levels of the metabolites carnitine, creatine, 3-hydroxyisovalerate, phenylalanine, asparagine, creatine phosphate, and methionine. In the LL group, a correlation was observed between changes in muscle thickness of the vastus lateralis muscle and levels of the metabolites acetoacetate, creatine phosphate, and oxypurinol. These correlations seem to be related to the characteristics of activated muscle fibers, the metabolic demand of the training protocols used, and the process of protein synthesis.
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Goodenough CG, Partin RE, Ness KK. Skeletal Muscle and Childhood Cancer: Where are we now and where we go from here. AGING AND CANCER 2021; 2:13-35. [PMID: 34541550 PMCID: PMC8445321 DOI: 10.1002/aac2.12027] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 05/03/2021] [Indexed: 12/22/2022]
Abstract
Skeletal muscle (muscle) is essential for physical health and for metabolic integrity, with sarcopenia (progressive muscle mass loss and weakness), a pre-curser of aging and chronic disease. Loss of lean mass and muscle quality (force generation per unit of muscle) in the general population are associated with fatigue, weakness, and slowed walking speed, eventually interfering with the ability to maintain physical independence, and impacting participation in social roles and quality of life. Muscle mass and strength impairments are also documented during childhood cancer treatment, which often persist into adult survivorship, and contribute to an aging phenotype in this vulnerable population. Although several treatment exposures appear to confer increased risk for loss of mass and strength that persists after therapy, the pathophysiology responsible for poor muscle quantity and quality is not well understood in the childhood cancer survivor population. This is partly due to limited access to both pediatric and adult survivor muscle tissue samples, and to difficulties surrounding non-invasive investigative approaches for muscle assessment. Because muscle accounts for just under half of the body's mass, and is essential for movement, metabolism and metabolic health, understanding mechanisms of injury responsible for both initial and persistent dysfunction is important, and will provide a foundation for intervention. The purpose of this review is to provide an overview of the available evidence describing associations between childhood cancer, its treatment, and muscle outcomes, identifying gaps in current knowledge.
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Affiliation(s)
- Chelsea G. Goodenough
- Epidemiology and Cancer Control Department, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Robyn E. Partin
- Epidemiology and Cancer Control Department, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Kirsten K. Ness
- Epidemiology and Cancer Control Department, St. Jude Children’s Research Hospital, Memphis, TN, USA
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Chaudhari AJ, Raynor WY, Gholamrezanezhad A, Werner TJ, Rajapakse CS, Alavi A. Total-Body PET Imaging of Musculoskeletal Disorders. PET Clin 2021; 16:99-117. [PMID: 33218607 PMCID: PMC7684980 DOI: 10.1016/j.cpet.2020.09.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Imaging of musculoskeletal disorders, including arthritis, infection, osteoporosis, sarcopenia, and malignancies, is often limited when using conventional modalities such as radiography, computed tomography (CT), and MR imaging. As a result of recent advances in Positron Emission Tomography (PET) instrumentation, total-body PET/CT offers a longer axial field-of-view, higher geometric sensitivity, and higher spatial resolution compared with standard PET systems. This article discusses the potential applications of total-body PET/CT imaging in the assessment of musculoskeletal disorders.
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Affiliation(s)
- Abhijit J Chaudhari
- Department of Radiology, University of California Davis, 4860 Y Street, Sacramento, CA 95825, USA.
| | - William Y Raynor
- Department of Radiology, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA; Drexel University College of Medicine, 2900 West Queen Lane, Philadelphia, PA 19129, USA
| | - Ali Gholamrezanezhad
- Keck School of Medicine, University of Southern California, 1520 San Pablo Street, Los Angeles, CA 90033, USA
| | - Thomas J Werner
- Department of Radiology, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA
| | - Chamith S Rajapakse
- Department of Radiology, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA
| | - Abass Alavi
- Department of Radiology, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA
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de Meer K, van den Akker JT, Smulders Y, Stam F, Stehouwer CD, Finglas P. In Vivo Stable Isotope Measurements of Methyl Metabolism: Applications in Pathophysiology and Interventions. Food Nutr Bull 2018. [DOI: 10.1177/15648265020233s122] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
With intravenous infusion of doubly-labeled [2H3C-1-13C-] methionine and stable isotope enrichments in plasma free methionine and carbon dioxide in breath air, whole body transmethylation, transsulfuration, and remethylation rates can be calculated. This technique demonstrated impaired recycling as the major disturbance to explain hyperhomocysteinemia in patients with end-stage renal failure, and can be used to optimize interventions with folate, B6, and B12 supplementation in this patient group. Intravenous infusion of [2,3,3-2H3] serine has also been applied to demonstrate the appearance of [2H2]- as well as [2H1]-methionine in plasma and protein, suggesting transfer of a one-carbon group from serine via 5,10-methylenetetrahydrofolate in human hepatocyte cytosol and mitochondria, respectively. In sheep, tissue free methionine enrichments after infusion of universally labeled [U-13C] methionine showed the highest remethylation activity in postmortem investigation of jejunum, liver, and kidney tissue samples, but no such activity in muscle and brain samples. Methods to quantitate one-carbon acceptor metabolism pathways and folate metabolism have recently become available.
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Affiliation(s)
- Kees de Meer
- Institute for Cardiovascular Research (ICar-VU), Vrije Universiteit Medical Center in Amsterdam, Netherlands
| | - Johana T. van den Akker
- Institute for Cardiovascular Research (ICar-VU), Vrije Universiteit Medical Center in Amsterdam, Netherlands
| | - Yvo Smulders
- Institute for Cardiovascular Research (ICar-VU), Vrije Universiteit Medical Center in Amsterdam, Netherlands
| | - Frank Stam
- Institute for Cardiovascular Research (ICar-VU), Vrije Universiteit Medical Center in Amsterdam, Netherlands
| | - Coen D.A. Stehouwer
- Institute for Cardiovascular Research (ICar-VU), Vrije Universiteit Medical Center in Amsterdam, Netherlands
| | - Paul Finglas
- Nutrition & Consumer Science Division, Institute of Food Research in Norwich, United Kingdom
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Kinetic Modelling of Infection Tracers [ 18F]FDG, [ 68Ga]Ga-Citrate, [ 11C]Methionine, and [ 11C]Donepezil in a Porcine Osteomyelitis Model. CONTRAST MEDIA & MOLECULAR IMAGING 2017; 2017:9256858. [PMID: 29114181 PMCID: PMC5654273 DOI: 10.1155/2017/9256858] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 08/24/2017] [Indexed: 12/28/2022]
Abstract
Introduction Positron emission tomography (PET) is increasingly applied for infection imaging using [18F]FDG as tracer, but uptake is unspecific. The present study compares the kinetics of [18F]FDG and three other PET tracers with relevance for infection imaging. Methods A juvenile porcine osteomyelitis model was used. Eleven pigs underwent PET/CT with 60-minute dynamic PET imaging of [18F]FDG, [68Ga]Ga-citrate, [11C]methionine, and/or [11C]donepezil, along with blood sampling. For infectious lesions, kinetic modelling with one- and two-tissue-compartment models was conducted for each tracer. Results Irreversible uptake was found for [18F]FDG and [68Ga]Ga-citrate; reversible uptake was found for [11C]methionine (two-tissue model) and [11C]donepezil (one-tissue model). The uptake rate for [68Ga]Ga-citrate was slow and diffusion-limited. For the other tracers, the uptake rate was primarily determined by perfusion (flow-limited uptake). Net uptake rate for [18F]FDG and distribution volume for [11C]methionine were significantly higher for infectious lesions than for correspondingly noninfected tissue. For [11C]donepezil in pigs, labelled metabolite products appeared to be important for the analysis. Conclusions The kinetics of the four studied tracers in infection was characterized. For clinical applications, [18F]FDG remains the first-choice PET tracer. [11C]methionine may have a potential for detecting soft tissue infections. [68Ga]Ga-citrate and [11C]donepezil were not found useful for imaging of osteomyelitis.
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Horsager J, Lausten SB, Bender D, Munk OL, Keiding S. Hepatic metabolism of 11C-methionine and secretion of 11C-protein measured by PET in pigs. AMERICAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING 2017; 7:167-173. [PMID: 28913155 PMCID: PMC5596319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 08/17/2017] [Indexed: 06/07/2023]
Abstract
Hepatic amino acid metabolism and protein secretion are essential liver functions that may be altered during metabolic stress, e.g. after surgery. We wished to develop a dynamic liver PET method using the radiolabeled amino acid 11C-methionine to examine this question. Eleven 40-kg pigs were allocated to either laparotomy or pneumoperitoneum. 24 hours after surgery a 70-min dynamic PET scanning of the liver with arterial blood sampling was performed immediately after intravenous injection of 11C-methionine. Time course of arterial plasma 11C-methionine concentration was used as input function and that of liver tissue 11C-concentration as output function in an extended Patlak analysis that accounted for irreversible metabolism of 11C-methionine (hepatic systemic metabolic clearance Kmet) and secretion of 11C-protein + 11C-metabolites into blood (rate constant kloss). Appearance of 11C-proteins in arterial plasma was measured during the experiment. There were no statistically significant differences between the laparotomy group and the pneumoperitoneum group in any of the calculated parameters. Average mean hepatic systemic metabolic clearance Kmet was 0.212 mL plasma/mL liver tissue/min, secretion rate constant from liver to blood kloss 0.0054 min-1, flux of methionine Fflux 3.59 μmol methionine/mL liver tissue/min, and the appearance rate of 11C-proteins in plasma Rprot 0.048 kBq/mL plasma/min. There was significant correlation between Kmet and Rprot. In conclusion, the hepatic systemic metabolic clearance of 11C-methionine was significantly correlated to the appearance rate of 11C-proteins in plasma. It would be interesting to translate the present method to human studies for the development of a clinical quantitative test of hepatic protein secretion.
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Affiliation(s)
- Jacob Horsager
- Department of Nuclear Medicine and PET Centre, Aarhus University HospitalAarhus, Denmark
| | | | - Dirk Bender
- Department of Nuclear Medicine and PET Centre, Aarhus University HospitalAarhus, Denmark
| | - Ole Lajord Munk
- Department of Nuclear Medicine and PET Centre, Aarhus University HospitalAarhus, Denmark
| | - Susanne Keiding
- Department of Nuclear Medicine and PET Centre, Aarhus University HospitalAarhus, Denmark
- Department of Hepatology and Gastroenterology, Aarhus University HospitalAarhus, Denmark
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11C-L-methyl methionine dynamic PET/CT of skeletal muscle: response to protein supplementation compared to L-[ring 13C 6] phenylalanine infusion with serial muscle biopsy. Ann Nucl Med 2017; 31:295-303. [PMID: 28260185 PMCID: PMC5397459 DOI: 10.1007/s12149-017-1157-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 02/01/2017] [Indexed: 01/12/2023]
Abstract
Objective The objective of this study was to determine if clinical dynamic PET/CT imaging with 11C-L-methyl-methionine (11C-MET) in healthy older women can provide an estimate of tissue-level post-absorptive and post-prandial skeletal muscle protein synthesis that is consistent with the more traditional method of calculating fractional synthesis rate (FSR) of muscle protein synthesis from skeletal muscle biopsies obtained during an infusion of L-[ring 13C6] phenylalanine (13C6-Phe). Methods Healthy older women (73 ± 5 years) completed both dynamic PET/CT imaging with 11C-MET and a stable isotope infusion of 13C6-Phe with biopsies to measure the skeletal muscle protein synthetic response to 25 g of a whey protein supplement. Graphical estimation of the Patlak coefficient Ki from analysis of the dynamic PET/CT images was employed as a measure of incorporation of 11 C-MET in the mid-thigh muscle bundle. Results Post-prandial values [mean ± standard error of the mean (SEM)] were higher than post-absorptive values for both Ki (0.0095 ± 0.001 vs. 0.00785 ± 0.001 min−1, p < 0.05) and FSR (0.083 ± 0.008 vs. 0.049 ± 0.006%/h, p < 0.001) in response to the whey protein supplement. The percent increase in Ki and FSR in response to the whey protein supplement was significantly correlated (r = 0.79, p = 0.015). Conclusions Dynamic PET/CT imaging with 11C-MET provides an estimate of the post-prandial anabolic response that is consistent with a traditional, invasive stable isotope, and muscle biopsy approach. These results support the potential future use of 11C-MET imaging as a non-invasive method for assessing conditions affecting skeletal muscle protein synthesis.
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Abstract
Positron emission tomography (PET) is an extraordinarily sensitive clinical imaging modality for interrogating tumor metabolism. Radiolabeled PET substrates can be traced at subphysiological concentrations, allowing noninvasive imaging of metabolism and intratumoral heterogeneity in systems ranging from advanced cancer models to patients in the clinic. There are a wide range of novel and more established PET radiotracers, which can be used to investigate various aspects of the tumor, including carbohydrate, amino acid, and fatty acid metabolism. In this review, we briefly discuss the more established metabolic tracers and describe recent work on the development of new tracers. Some of the unanswered questions in tumor metabolism are considered alongside new technical developments, such as combined PET/magnetic resonance imaging scanners, which could provide new imaging solutions to some of the outstanding diagnostic challenges facing modern cancer medicine.
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Affiliation(s)
- David Y. Lewis
- Cancer Research UK - Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Cambridge, UK
| | - Dmitry Soloviev
- Cancer Research UK - Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Cambridge, UK
| | - Kevin M. Brindle
- Cancer Research UK - Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Cambridge, UK
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Abstract
Over recent years, there has been a rapid expansion in our knowledge of the factors that regulate tumor growth; this has resulted in the identification of new therapeutic targets and improvements in the long-term survival of cancer patients. New noninvasive biomarkers of drug targets and pathway modulation in vivo are needed to guide therapy selection and detect drug resistance early so that alternative, more effective treatments can be offered. The translation of new therapeutics into the clinic is disappointingly slow, expensive, and subject to high rates of attrition often occurring at late stages (phase 3) of development. In an attempt to mitigate these delays and failures, there has been resurgence in the development of new molecular imaging probes for studies with positron emission tomography (PET) to characterize tumor biology. In the assessment of therapeutic effects, PET allows imaging of entire tumor burden in a noninvasive repeatable manner. This chapter focuses on the clinical translation of PET imaging agents from bench to bedside. New probes are being used to study a diverse range of processes such as angiogenesis, apoptosis, fatty acid metabolism, and growth factor receptor expression. In the future, validation of these novel imaging probes could allow more innovative therapies to be adapted earlier in the clinic leading to improved patient outcomes.
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Affiliation(s)
- Laura M Kenny
- Comprehensive Cancer Imaging Centre, Department of Surgery & Cancer, Imperial College London, London, United Kingdom
| | - Eric O Aboagye
- Comprehensive Cancer Imaging Centre, Department of Surgery & Cancer, Imperial College London, London, United Kingdom.
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Xu H, Yu YM, Ma H, Carter EA, Fagan S, Tompkins RG, Fischman AJ. Glucose metabolism during the early "flow phase" after burn injury. J Surg Res 2012; 179:e83-90. [PMID: 22459295 DOI: 10.1016/j.jss.2012.02.037] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Revised: 01/06/2012] [Accepted: 02/17/2012] [Indexed: 12/28/2022]
Abstract
BACKGROUND Burn injury (BI) is associated with insulin resistance (IR) and hyperglycemia which complicate clinical management. We investigated the impact of BI on glucose metabolism in a rabbit model of BI using a combination of positron emission tomography (PET) and stable isotope studies under euglycemic insulin clamp (EIC) conditions. MATERIALS AND METHODS Twelve male rabbits were subjected to either full-thickness BI (B) or sham burn. An EIC condition was established by constant infusion of insulin, concomitantly with a variable rate of dextrose infusion 3 d after treatment. PET imaging of the hind limbs was conducted to determine the rates of peripheral O(2) and glucose utilization. Each animal also received a primed constant infusion of [6,6-(2)H(2)] glucose to determine endogenous glucose production. RESULTS The fasting blood glucose in the burned rabbits was higher than that in the sham group. Under EIC conditions, the sham burn group required more exogenous dextrose than the B group to maintain blood glucose at physiological levels (22.2 ± 2.6 versus 13.3 ± 2.9 mg/min, P < 0.05), indicating a state of IR. PET imaging demonstrated that the rates of O(2) consumption and (18)F 2-fluoro-2-deoxy-D-glucose utilization by skeletal muscle remained at similar levels in both groups. Hepatic gluconeogenesis determined by the stable isotope tracer study was found significantly increased in the B group. CONCLUSIONS These findings demonstrated that hyperglycemia and IR develop during the early "flow phase" after BI. Unsuppressed hepatic gluconeogenesis, but not peripheral skeletal muscular utilization of glucose, contributes to hyperglycemia at this stage.
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Affiliation(s)
- Hongzhi Xu
- Department of Surgery, Massachusetts General Hospital, Harvard Medical School and Shriners Hospitals for Children, Boston, Massachusetts, USA.
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Body distribution of C-methionine and FDG in rat measured by microPET. Interdiscip Toxicol 2011; 4:52-5. [PMID: 21577285 PMCID: PMC3090055 DOI: 10.2478/v10102-011-0010-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2011] [Revised: 03/10/2011] [Accepted: 03/13/2011] [Indexed: 11/20/2022] Open
Abstract
Compounds 18F-fluorodeoxyglucose (18FDG) and 11C-methionine (11C-MET) are radiodiagnostics frequently used in clinical Positron Emission Tomography (PET) as well in preclinical studies of various pathologies. The present study was focused on the comparison of biodistribution of both radiotracers in intact Wistar rats. The animals were scanned by microPET twice. The first scanning was done after 11C-MET administration, the second scan followed 5–7 days later using 18FDG. The radiotracers were injected into the tail vein of animals in isoflurane anesthesia. After a redistribution period, whole body scans were obtained using eXplore Vista SrT GE tomograph. Accumulation of the drugs in tissues was expressed in relative values (% ID/g) in selected regions of interest. As arbitrary reference tissue for drug accumulation, the sternoclavicular area was used. 18C-MET was found remarkably cumulating especially in the liver, spleen and distal part of the gastrointestinal tract. The compound was accumulated in the liver 6.9±0.92 (mean±SEM) times more intensively than in the reference tissue. The respective value for spleen and cecum/colon was 5.62±0.81 and 3.56±0.14 times. Accumulation of 11C-MET in other body parts including the brain and heart was very low and was apparently equal to the arbitrary tissue (0.13±0.01% ID/g). In the same animals 18FDG (biontFDG) was remarkably cumulated especially in Harderian glands compared to arbitrary tissue background (11.02±1.00 times), heart (7.52±1.70 times), brain (6.14±0.37 times), and colon (5.68±0.31 times). 18FDG accumulation in the liver, spleen and other organs was apparently not different from that found in the background (0.14±0.02% ID/g). The data obtained may serve as reference values in further microPET preclinical studies with 11C-MET and 18FDG under the given conditions.
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Skovgaard D, Kjaer A, Heinemeier KM, Brandt-Larsen M, Madsen J, Kjaer M. Use of cis-[18F]fluoro-proline for assessment of exercise-related collagen synthesis in musculoskeletal connective tissue. PLoS One 2011; 6:e16678. [PMID: 21347251 PMCID: PMC3037959 DOI: 10.1371/journal.pone.0016678] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Accepted: 12/23/2010] [Indexed: 01/28/2023] Open
Abstract
Protein turnover in collagen rich tissue is influenced by exercise, but can only with difficulty be studied in vivo due to use of invasive procedure. The present study was done to investigate the possibility of applying the PET-tracer, cis-[18F]fluoro-proline (cis-Fpro), for non-invasive assessment of collagen synthesis in rat musculoskeletal tissues at rest and following short-term (3 days) treadmill running. Musculoskeletal collagen synthesis was studied in rats at rest and 24 h post-exercise. At each session, rats were PET scanned at two time points following injection of cis-FPro: (60 and 240 min p.i). SUV were calculated for Achilles tendon, calf muscle and tibial bone. The PET-derived results were compared to mRNA expression of collagen type I and III. Tibial bone had the highest SUV that increased significantly (p<0.001) from the early (60 min) to the late (240 min) PET scan, while SUV in tendon and muscle decreased (p<0.001). Exercise had no influence on SUV, which was contradicted by an increased gene expression of collagen type I and III in muscle and tendon. The clearly, visible uptake of cis-Fpro in the collagen-rich musculoskeletal tissues is promising for multi-tissue studies in vivo. The tissue-specific differences with the highest basal uptake in bone are in accordance with earlier studies relying on tissue incorporation of isotopic-labelled proline. A possible explanation of the failure to demonstrate enhanced collagen synthesis following exercise, despite augmented collagen type I and III transcription, is that SUV calculations are not sensitive enough to detect minor changes in collagen synthesis. Further studies including kinetic compartment modeling must be performed to establish whether cis-Fpro can be used for non-invasive in-vivo assessment of exercise-induced changes in musculoskeletal collagen synthesis.
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Affiliation(s)
- Dorthe Skovgaard
- Institute of Sports Medicine Copenhagen, Bispebjerg Hospital and Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
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15
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Deng H, Tang X, Wang H, Tang G, Wen F, Shi X, Yi C, Wu K, Meng Q. S-11C-Methyl-L-Cysteine: A New Amino Acid PET Tracer for Cancer Imaging. J Nucl Med 2011; 52:287-93. [DOI: 10.2967/jnumed.110.081349] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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16
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Lang T, Streeper T, Cawthon P, Baldwin K, Taaffe DR, Harris TB. Sarcopenia: etiology, clinical consequences, intervention, and assessment. Osteoporos Int 2010; 21:543-59. [PMID: 19779761 PMCID: PMC2832869 DOI: 10.1007/s00198-009-1059-y] [Citation(s) in RCA: 470] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2009] [Accepted: 08/18/2009] [Indexed: 02/07/2023]
Abstract
The aging process is associated with loss of muscle mass and strength and decline in physical functioning. The term sarcopenia is primarily defined as low level of muscle mass resulting from age-related muscle loss, but its definition is often broadened to include the underlying cellular processes involved in skeletal muscle loss as well as their clinical manifestations. The underlying cellular changes involve weakening of factors promoting muscle anabolism and increased expression of inflammatory factors and other agents which contribute to skeletal muscle catabolism. At the cellular level, these molecular processes are manifested in a loss of muscle fiber cross-sectional area, loss of innervation, and adaptive changes in the proportions of slow and fast motor units in muscle tissue. Ultimately, these alterations translate to bulk changes in muscle mass, strength, and function which lead to reduced physical performance, disability, increased risk of fall-related injury, and, often, frailty. In this review, we summarize current understanding of the mechanisms underlying sarcopenia and age-related changes in muscle tissue morphology and function. We also discuss the resulting long-term outcomes in terms of loss of function, which causes increased risk of musculoskeletal injuries and other morbidities, leading to frailty and loss of independence.
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Affiliation(s)
- T Lang
- Department of Radiology and Biomedical Imaging, University of California, UCSF, San Francisco, CA 94143-0946, USA.
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17
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Smith GI, Villareal DT, Lambert CP, Reeds DN, Mohammed BS, Mittendorfer B. Timing of the initial muscle biopsy does not affect the measured muscle protein fractional synthesis rate during basal, postabsorptive conditions. J Appl Physiol (1985) 2009; 108:363-8. [PMID: 19940095 DOI: 10.1152/japplphysiol.00957.2009] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The muscle protein fractional synthesis rate (FSR) is determined by monitoring the incorporation of an amino acid tracer into muscle protein during a constant-rate intravenous tracer infusion. Commonly two sequential muscle biopsies are obtained some time after starting the tracer infusion. However, other protocols, including those with an initial biopsy before starting the tracer infusion to measure the background enrichment and those with only a single biopsy after several hours of tracer infusion have been used. To assess the validity of these approaches, we compared the muscle protein FSR obtained by calculating the difference in [ring-(2)H(5)]phenylalanine and [5,5,5-(2)H(3)]leucine incorporation into muscle protein at approximately 3.5 h after starting the tracer infusion and 1) at 60 min; 2) before starting the tracer infusion (background enrichment); 3) a population average muscle protein background enrichment; and 4) by measuring the tracer incorporation into muscle protein at approximately 3.5 h assuming essentially no background enrichment. Irrespective of the tracer used, the muscle protein FSR calculated from the difference in the muscle protein labeling several hours after starting the tracer infusion and either the labeling at 60 min or the background enrichment were not different (e.g., 0.049 +/- 0.007%/h vs. 0.049 +/- 0.007%/h, respectively, with [(2)H(5)]phenylalanine; P = 0.99). However, omitting the initial biopsy and assuming no background enrichment yielded average FSR values that were approximately 15% (with [(2)H(5)]phenylalanine) to 80% (with [(2)H(3)]leucine) greater (P < or = 0.059); using a population average background enrichment reduced the difference to approximately 3% (P = 0.76) and 22% (P = 0.52) with [(2)H(5)]phenylalanine and [(2)H(3)]leucine, respectively. We conclude that during basal, postabsorptive conditions, valid muscle protein FSR values can be obtained irrespective of the timing of the initial biopsy so long as the protein labeling in two sequential biopsies is measured whereas the single biopsy approach should be avoided.
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Affiliation(s)
- Gordon I Smith
- Washington Univ. School of Medicine, 660 South Euclid Ave., Campus Box 8031, St. Louis, MO 63110, USA
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18
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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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19
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Amino-acid-based peritoneal dialysis solution improves amino-acid transport into skeletal muscle. Kidney Int 2008:S131-6. [PMID: 18379536 DOI: 10.1038/sj.ki.5002614] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Abnormalities of amino-acid (AA) and protein metabolism are known to occur in chronic kidney disease (CKD). Protein malnutrition may contribute to impaired prognosis of dialysis patients. A crucial step in protein metabolism is AA transport into the cells. We compared the effects of an AA-containing peritoneal dialysis (PD) solution to glucose-based solutions on skeletal muscle AA uptake. Thirteen nondiabetic PD patients were studied twice in a random order and in a crossover manner both in the fasting state and during euglycemic insulin stimulation using [(11)C]methylaminoisobutyrate ([(11)C]MeAIB) and positron emission tomography (PET). Before both PET study days, patients had been using either glucose-based PD solutions only or one daily bag of AA solution in addition to glucose-based PD solutions for at least 6 weeks. Skeletal muscle AA uptake was calculated with graphical analysis. AA-containing PD solution increased plasma AA concentrations from 2.18+/-0.34 to 3.08+/-0.55 mmol l(-1) in the fasting state (P=0.0002) and from 1.88+/-0.15 to 2.42+/-0.30 mmol l(-1) during insulin stimulation (P<0.0001). As compared to PD treatment using glucose-based solutions only, skeletal muscle AA uptake was significantly higher during treatment containing AA solution both in the fasting state (15.2+/-5.8 vs 20.0+/-5.6 micromol kg(-1) min(-1), respectively, P=0.0057) and during insulin stimulation (16.8+/-4.5 vs 21.1+/-4.9 micromol kg(-1) min(-1), respectively, P=0.0046). In conclusion, PD treatment with an AA-containing PD solution is associated with a significant increase in skeletal muscle AA uptake both in the fasting state and during insulin stimulation.
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Buus S, Grau C, Munk OL, Bender D, Jensen K, Keiding S. 11C-methionine PET, a novel method for measuring regional salivary gland function after radiotherapy of head and neck cancer. Radiother Oncol 2005; 73:289-96. [PMID: 15588873 DOI: 10.1016/j.radonc.2004.09.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2004] [Revised: 09/15/2004] [Accepted: 09/17/2004] [Indexed: 10/26/2022]
Abstract
BACKGROUND AND PURPOSE Loss of salivary gland function is a distressing side-effect of radiotherapy (RT) for head and neck cancer. The aim of this study was to develop a positron emission tomography (PET) method for measuring regional salivary gland function in the major salivary glands irradiated during RT. PATIENTS AND METHODS Eight head and neck cancer patients were included; two were examined before RT and six after parotid sparing RT. Patients were examined by dynamic 11C-methionine PET of the major salivary glands and parotid gland salivary flow measurements. PET data were analysed using a kinetic model of salivary gland 11C-methionine metabolism, in which salivary gland function was quantified by the net metabolic clearance of 11C-methionine, K. Functional voxel-wise images of K were calculated and matched with the CT-dose-plan for comparing regional salivary gland function with the regional radiation dose. RESULTS Parotid gland K correlated positively with parotid gland salivary flow, indicating that K can be used as an index of salivary gland function. K of parotid and submandibular glands was reduced dependent on the median radiation dose. In one patient, receiving a heterogeneous radiation dose to the parotid glands, regional salivary gland function was inversely correlated to the regional radiation dose. CONCLUSIONS Salivary gland function can be measured by dynamic 11C-methionine PET. The net metabolic clearance of 11C-methionine of salivary glands was reduced dependent on the radiation dose. Dynamic 11C-methionine PET offers a method for studying the individual response of the major salivary glands to irradiation.
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Affiliation(s)
- Simon Buus
- PET Centre, Aarhus University Hospital, Noerrebrogade 44, 8000 Aarhus C, Denmark
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21
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Abstract
This review is divided into two parts, the first dealing with the cell and molecular biology of muscle in terms of growth and wasting and the second being an account of current knowledge of physiological mechanisms involved in the alteration of size of the human muscle mass. Wherever possible, attempts have been made to interrelate the information in each part and to provide the most likely explanation for phenomena that are currently only partially understood. The review should be of interest to cell and molecular biologists who know little of human muscle physiology and to physicians, physiotherapists, and kinesiologists who may be familiar with the gross behavior of human muscle but wish to understand more about the underlying mechanisms of change.
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Affiliation(s)
- Michael J Rennie
- Division of Molecular Physiology, School of Life Sciences, University of Dundee, Dundee, DD1 4HN, Scotland, United Kingdom.
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22
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Ionescu AA, Nixon LS, Luzio S, Lewis-Jenkins V, Evans WD, Stone MD, Owens DR, Routledge PA, Shale DJ. Pulmonary function, body composition, and protein catabolism in adults with cystic fibrosis. Am J Respir Crit Care Med 2002; 165:495-500. [PMID: 11850342 DOI: 10.1164/ajrccm.165.4.2104065] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Increased survival in cystic fibrosis (CF) is associated with bone thinning and fat-free mass (FFM) loss. We hypothesized that the severity of lung disease would be associated with increased protein catabolism and systemic inflammatory status in clinically stable patients. Forty adults with CF and 22 age-matched healthy subjects were studied. Body composition was determined by dual-energy X-ray absorptiometry. Urinary pseudouridine (PSU), a marker of protein breakdown, and cross-linked N-telopeptides of type I collagen (NTx), a marker of bone connective tissue breakdown, serum tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, and their soluble receptors were measured. A 3-d food intake diary revealed 21 patients had a low energy intake. Excretion of PSU (p = 0.019) and NTx (p < 0.01) was increased in patients and was inversely related to FEV(1); PSU (r = - 0.53, p = 0.001) and NTx (r = - 0.43, p < 0.01). Increased excretion of PSU and NTx (p < 0.05 for both) was also related to a low FFM. All inflammatory mediators were greater in patients and were related to PSU and NTx. Clinically stable adults were catabolic with both cellular and connective tissue protein breakdown, which was related to lung disease severity, systemic inflammation, and body composition.
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Affiliation(s)
- Alina A Ionescu
- Section of Respiratory Medicine, Bone Research Unit, Department of Geriatrics, University of Wales College of Medicine, Academic Centre, University Hospital of Wales and Llandough Hospital NHS Trust, Penarth, South Glamorgan, United Kingdom
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Young VR, Ajami A. The Rudolf Schoenheimer Centenary Lecture. Isotopes in nutrition research. Proc Nutr Soc 1999; 58:15-32. [PMID: 10343336 DOI: 10.1079/pns19990004] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The present lecture begins with a brief overview of the professional and scientific journey taken by Rudolf Schoenheimer, before turning to a discussion of the power of isotopic tracers in nutrition research. Schoenheimer's remarkable contributions to the study of intermediary metabolism and the turnover of body constituents, based initially on compounds tagged with 2H and later with 15N, spanned a mere decade. It is difficult, however, to overestimate the enormous impact of Schoenheimer's research on the evolution of biological science. After a relative hiatus, following Schoenheimer's death in 1941, in the use of stable nuclides as tracers in metabolism and nutrition, especially in human subjects, there is now an expanded and exciting range of techniques, experimental protocols and stable-isotope tracer compounds that are helping to probe the dynamic aspects of the metabolism of the major energy-yielding substrates, amino acids and other N-containing compounds, vitamins and mineral elements in human subjects. Various aspects of the contemporary applications of these tracers in nutrition research are covered in the present lecture.
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Affiliation(s)
- V R Young
- Laboratory of Human Nutrition, School of Science, Massachusetts Institute of Technology, Cambridge 02139, USA.
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