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Armbruster RR, Kumar D, Benyard B, Jacobs P, Khandavilli A, Liu F, Nanga RPR, McCormack S, Cappola AR, Wilson N, Reddy R. Personalized and muscle-specific OXPHOS measurement with integrated CrCEST MRI and proton MR spectroscopy. Nat Commun 2024; 15:5387. [PMID: 38918361 PMCID: PMC11199598 DOI: 10.1038/s41467-024-49253-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Accepted: 05/29/2024] [Indexed: 06/27/2024] Open
Abstract
Creatine chemical exchange saturation transfer (CrCEST) MRI is an emerging high resolution and noninvasive method for measuring muscle specific oxidative phosphorylation (OXPHOS). However, CrCEST measurements are sensitive to changes in muscle pH, which might confound the measurement and interpretation of creatine recovery time (τCr). Even with the same prescribed exercise stimulus, the extent of acidification and hence its impact on τCr is expected to vary between individuals. To address this issue, a method to measure pH pre- and post-exercise and its impact on CrCEST MRI with high temporal resolution is needed. In this work, we integrate carnosine 1H- magnetic resonance spectroscopy (MRS) and 3D CrCEST to establish "mild" and "moderate/intense" exercise stimuli. We then test the dependence of CrCEST recovery time on pH using different exercise stimuli. This comprehensive metabolic imaging protocol will enable personalized, muscle specific OXPHOS measurements in both healthy aging and myriad other disease states impacting muscle mitochondria.
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Affiliation(s)
- Ryan R Armbruster
- Department of Radiology, Center for Advanced Metabolic Imaging in Precision Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Dushyant Kumar
- Department of Radiology, Center for Advanced Metabolic Imaging in Precision Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Blake Benyard
- Department of Radiology, Center for Advanced Metabolic Imaging in Precision Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Paul Jacobs
- Department of Radiology, Center for Advanced Metabolic Imaging in Precision Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Aditi Khandavilli
- Department of Biology, Department of Nutrition and Science, Cornell University, Ithaca, NY, 14850, USA
| | - Fang Liu
- Department of Biostatistics, Epidemiology, and Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Ravi Prakash Reddy Nanga
- Department of Radiology, Center for Advanced Metabolic Imaging in Precision Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Shana McCormack
- Neuroendocrine Center, Division of Endocrinology and Diabetes, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - Anne R Cappola
- Division of Endocrinology, Diabetes, and Metabolism, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Neil Wilson
- Department of Radiology, Center for Advanced Metabolic Imaging in Precision Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Ravinder Reddy
- Department of Radiology, Center for Advanced Metabolic Imaging in Precision Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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Chen X, Huang Y, Liu S, Yi J, Chen W, Wang Y, Pan C. Functional magnetic resonance imaging evaluation of masticatory muscle dysfunction in unilateral exodontia rabbits. Dentomaxillofac Radiol 2022; 51:20220022. [PMID: 35466684 PMCID: PMC10043606 DOI: 10.1259/dmfr.20220022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Objective: Occlusal alteration due to tooth loss may cause overload of masticatory muscle and promote muscle dysfunction. This study explored the feasibility of using functional magnetic resonance imaging (fMRI) to evaluate muscle dysfunction in an established unilateral exodontia animal model. Methods: six rabbits were extracted right maxillary molars. T2 mapping, T2* mapping and Iterative Decomposition of water and fat with Echo Asymmetry and Least Square Estimation (IDEAL-IQ) were performed one day before extraction and every 2 weeks (2th~12th week) after extraction. The T2 and T2* values and fat fraction (FF) of bilateral temporal muscle (TM), masseter muscle (MM) and medial pterygoid muscle (MPM) were measured and compared between the extraction side-and the contralateral side. Parameters of three monitoring time points (0th, sixth, 12th week) were also analyzed. Results: T2 values of MM on extraction side-were significantly higher than those of contralateral side-from fourth week to 12th week after extraction (p < 0.05). T2 values of MM and MPM on extraction side-and TM on contralateral side-were significantly higher in 12th week than those in 0th week (p < 0.05). And FF of bilateral MM was significantly higher in 12th week than those in 0th week (p < 0.05). T2* value showed no significant difference between extraction side-and contralateral side-and also at above three time points. Conclusion: T2 and T2* value and FF can be used as indicators of masticatory muscle dysfunction. fMRI is expected to be a non-invasive method for in vivo and real-time evaluation of masticatory muscle functional abnormality.
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Affiliation(s)
- Xuexia Chen
- Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, PR China
| | - Yi Huang
- Department of Radiology, Hwa Mei Hospital, University of Chinese Academy of Sciences, Ningbo, PR China
| | - Simin Liu
- Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, PR China
| | - Jingru Yi
- Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, PR China
| | - Weiwei Chen
- Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, PR China
| | - Yang Wang
- Department of Orthopaedic Surgery, the Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, PR China
| | - Chu Pan
- Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, PR China
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Dolan E, Warren DE, Harris RC, Sale C, Gualano B, Saunders B. Skeletal muscle histidine-containing dipeptide contents are increased in freshwater turtles (C. picta bellii) with cold-acclimation. Comp Biochem Physiol A Mol Integr Physiol 2021; 262:111071. [PMID: 34492385 DOI: 10.1016/j.cbpa.2021.111071] [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: 06/15/2021] [Revised: 09/01/2021] [Accepted: 09/02/2021] [Indexed: 10/20/2022]
Abstract
Freshwater turtles found in higher latitudes can experience extreme challenges to acid-base homeostasis while overwintering, due to a combination of cold temperatures along with the potential for environmental hypoxia. Histidine-containing dipeptides (HCDs; carnosine, anserine and balenine) may facilitate pH regulation in response to these challenges, through their role as pH buffers. We measured the HCD content of three tissues (liver, cardiac and skeletal muscle) from the anoxia-tolerant painted turtle (C. picta bellii) acclimated to either 3 or 20 °C. HCDs were detected in all tissues, with the highest content shown in the skeletal muscle. Turtles acclimated to 3 °C had more HCD in their skeletal muscle than those acclimated to 20 °C (carnosine = 20.8 ± 4.5 vs 12.5 ± 5.9 mmol·kg DM-1; ES = 1.59 (95%CI: 0.16-3.00), P = 0.013). The higher HCD content shown in the skeletal muscle of the cold-acclimated turtles suggests a role in acid-base regulation in response to physiological challenges associated with living in the cold, with the increase possibly related to the temperature sensitivity of carnosine's dissociation constant.
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Affiliation(s)
- Eimear Dolan
- Applied Physiology and Nutrition Research Group, School of Physical Education and Sport, Rheumatology Division, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, SP, Brazil
| | - Daniel E Warren
- Department of Biology, Saint Louis University, MO, United States.
| | | | - Craig Sale
- Musculoskeletal Physiology Research Group, Sport Health and Performance Enhancement Research Centre, School of Science and Technology, Nottingham Trent University, Nottingham, United Kingdom
| | - Bruno Gualano
- Applied Physiology and Nutrition Research Group, School of Physical Education and Sport, Rheumatology Division, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, SP, Brazil; Food Research Centre, University of Sao Paulo, Sao Paulo, Brazil
| | - Bryan Saunders
- Applied Physiology and Nutrition Research Group, School of Physical Education and Sport, Rheumatology Division, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, SP, Brazil; Institute of Orthopaedics and Traumatology, Faculty of Medicine FMUSP, University of São Paulo, Brazil.
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4
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Anti-cancer actions of carnosine and the restoration of normal cellular homeostasis. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2021; 1868:119117. [PMID: 34384791 DOI: 10.1016/j.bbamcr.2021.119117] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 05/16/2021] [Accepted: 08/05/2021] [Indexed: 12/15/2022]
Abstract
Carnosine is a naturally occurring dipeptide found in meat. Alternatively it can be formed through synthesis from the amino acids, β-alanine and L-histidine. Carnosine has long been advocated for use as an anti-oxidant and anti-glycating agent to facilitate healthy ageing, and there have also been reports of it having anti-proliferative effects that have beneficial actions against the development of a number of different cancers. Carnosine is able to undertake multiple molecular processes, and it's mechanism of action therefore remains controversial - both in healthy tissues and those associated with cancer or metabolic diseases. Here we review current understanding of its mechanistic role in different physiological contexts, and how this relates to cancer. Carnosine turns over rapidly in the body due to the presence of both serum and tissue carnosinase enzymes however, so its use as a dietary supplement would require ingestion of multiple daily doses. Strategies are therefore being developed that are based upon either resistance of carnosine analogs to enzymatic turnover, or else β-alanine supplementation, and the development of these potential therapeutic agents is discussed.
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Krššák M, Lindeboom L, Schrauwen‐Hinderling V, Szczepaniak LS, Derave W, Lundbom J, Befroy D, Schick F, Machann J, Kreis R, Boesch C. Proton magnetic resonance spectroscopy in skeletal muscle: Experts' consensus recommendations. NMR IN BIOMEDICINE 2021; 34:e4266. [PMID: 32022964 PMCID: PMC8244035 DOI: 10.1002/nbm.4266] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 12/21/2019] [Accepted: 01/15/2020] [Indexed: 05/02/2023]
Abstract
1 H-MR spectroscopy of skeletal muscle provides insight into metabolism that is not available noninvasively by other methods. The recommendations given in this article are intended to guide those who have basic experience in general MRS to the special application of 1 H-MRS in skeletal muscle. The highly organized structure of skeletal muscle leads to effects that change spectral features far beyond simple peak heights, depending on the type and orientation of the muscle. Specific recommendations are given for the acquisition of three particular metabolites (intramyocellular lipids, carnosine and acetylcarnitine) and for preconditioning of experiments and instructions to study volunteers.
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Affiliation(s)
- Martin Krššák
- Division of Endocrinology and Metabolism, Department of Internal Medicine III & High Field MR Centre, Department of Biomedical Imaging and Image guided TherapyMedical University of ViennaViennaAustria
| | - Lucas Lindeboom
- Department of Radiology and Nuclear Medicine and Department of Nutrition and Movement ScienceMaastricht University Medical CenterMaastrichtThe Netherlands
| | - Vera Schrauwen‐Hinderling
- Department of Radiology and Nuclear Medicine and Department of Nutrition and Movement ScienceMaastricht University Medical CenterMaastrichtThe Netherlands
| | - Lidia S. Szczepaniak
- Biomedical Research Consulting in Magnetic Resonance SpectroscopyAlbuquerqueNew Mexico
| | - Wim Derave
- Department of Movement and Sports SciencesGhent UniversityGhentBelgium
| | - Jesper Lundbom
- Department of Diagnostics and TherapeuticsUniversity of HelsinkiHelsinkiFinland
| | | | - Fritz Schick
- Section on Experimental Radiology, Department of Diagnostic and Interventional RadiologyUniversity Hospital TübingenTübingenGermany
| | - Jürgen Machann
- Section on Experimental Radiology, Department of Diagnostic and Interventional RadiologyUniversity Hospital TübingenTübingenGermany
- Institute for Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University of TübingenTübingenGermany
- German Center for Diabetes Research (DZD)TübingenGermany
| | - Roland Kreis
- Departments of Radiology and Biomedical ResearchUniversity and InselspitalBernSwitzerland
| | - Chris Boesch
- Departments of Radiology and Biomedical ResearchUniversity and InselspitalBernSwitzerland
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6
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Patel KA, Farias de Oliveira L, Sale C, James RM. The effect of β-alanine supplementation on high intensity cycling capacity in normoxia and hypoxia. J Sports Sci 2021; 39:1295-1301. [PMID: 33491594 DOI: 10.1080/02640414.2020.1867416] [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: 10/22/2022]
Abstract
The availability of dietary beta-alanine (BA) is the limiting factor in carnosine synthesis within human muscle due to its low intramuscular concentration and substrate affinity. Carnosine can accept hydrogen ions (H+), making it an important intramuscular buffer against exercise-induced acidosis. Metabolite accumulation rate increases when exercising in hypoxic conditions, thus an increased carnosine concentration could attenuate H+ build-up when exercising in hypoxic conditions. This study examined the effects of BA supplementation on high intensity cycling capacity in normoxia and hypoxia. In a double-blind design, nineteen males were matched into a BA group (n = 10; 6.4 g·d-1) or a placebo group (PLA; n = 9) and supplemented for 28 days, carrying out two pre- and two post-supplementation cycling capacity trials at 110% of powermax, one in normoxia and one in hypoxia (15.5% O2). Hypoxia led to a 9.1% reduction in exercise capacity, but BA supplementation had no significant effect on exercise capacity in normoxia or hypoxia (P > 0.05). Blood lactate accumulation showed a significant trial x time interaction post-supplementation (P = 0.016), although this was not significantly different between groups. BA supplementation did not increase high intensity cycling capacity in normoxia, nor did it improve cycling capacity in hypoxia even though exercise capacity was reduced under hypoxic conditions.
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Affiliation(s)
- Kiran Akshay Patel
- School of Science and Technology, Nottingham Trent University, Nottingham, UK
| | - Luana Farias de Oliveira
- Applied Physiology & Nutrition Research Group, School of Physical Education and Sport, Rheumatology Division, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, Brazil
| | - Craig Sale
- School of Science and Technology, Nottingham Trent University, Nottingham, UK
| | - Ruth M James
- School of Science and Technology, Nottingham Trent University, Nottingham, UK
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Huber FA, Del Grande F, Rizzo S, Guglielmi G, Guggenberger R. MRI in the assessment of adipose tissues and muscle composition: how to use it. Quant Imaging Med Surg 2020; 10:1636-1649. [PMID: 32742957 DOI: 10.21037/qims.2020.02.06] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Body composition analysis based on the characterization of different tissue compartments is currently experiencing increasing attention by a broad range of medical disciplines for both clinical and research questions. However, body composition profiling (BCP) can be performed utilizing different modalities, which all come along with several technical and diagnostic strengths and limitations, respectively. Magnetic resonance imaging (MRI) demonstrates good soft tissue resolution, high contrast between fat and water, and is free from ionizing radiation. This review article represents an overview of imaging techniques for body composition assessment, focussing on qualitative and quantitative methods of assessing adipose tissue and muscles in MRI.
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Affiliation(s)
- Florian Alexander Huber
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland
| | - Filippo Del Grande
- Istituto di imaging della Svizzera Italiana, Regional Hospital of Lugano, Lugano, Switzerland
| | - Stefania Rizzo
- Istituto di imaging della Svizzera Italiana, Regional Hospital of Lugano, Lugano, Switzerland
| | | | - Roman Guggenberger
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland
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Comparative physiology investigations support a role for histidine-containing dipeptides in intracellular acid–base regulation of skeletal muscle. Comp Biochem Physiol A Mol Integr Physiol 2019; 234:77-86. [DOI: 10.1016/j.cbpa.2019.04.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 04/17/2019] [Accepted: 04/18/2019] [Indexed: 12/17/2022]
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9
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Mankodi A, Azzabou N, Bulea T, Reyngoudt H, Shimellis H, Ren Y, Kim E, Fischbeck KH, Carlier PG. Skeletal muscle water T 2 as a biomarker of disease status and exercise effects in patients with Duchenne muscular dystrophy. Neuromuscul Disord 2017; 27:705-714. [PMID: 28601553 DOI: 10.1016/j.nmd.2017.04.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 04/19/2017] [Accepted: 04/19/2017] [Indexed: 12/16/2022]
Abstract
The purpose of this study was to examine exercise effects on muscle water T2 in patients with Duchenne muscular dystrophy (DMD). In 12 DMD subjects and 19 controls, lower leg muscle fat (%) was measured by Dixon and muscle water T2 and R2 (1/T2) by the tri-exponential model. Muscle water R2 was measured again at 3 hours after an ankle dorsiflexion exercise. The muscle fat fraction was higher in DMD participants than in controls (p < .001) except in the tibialis posterior muscle. Muscle water T2 was measured independent of the degree of fatty degeneration in DMD muscle. At baseline, muscle water T2 was higher in all but the extensor digitorum longus muscles of DMD participants than controls (p < .001). DMD participants had a lower muscle torque (p < .001) and exerted less power (p < .01) during exercise than controls. Nevertheless, muscle water R2 decreased (T2 increased) after exercise from baseline in DMD subjects and controls with greater changes in the target muscles of the exercise than in ankle plantarflexor muscles. Skeletal muscle water T2 is a sensitive biomarker of the disease status in DMD and of the exercise response in DMD patients and controls.
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Affiliation(s)
- Ami Mankodi
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA.
| | - Noura Azzabou
- NMR Laboratory, DRF, I2BM, MIRCen, Institute of Myology, Pitie-Salpetriere University Hospital and CEA, Paris, France
| | - Thomas Bulea
- Functional & Applied Biomechanics Section, Rehabilitation Medicine Department, Clinical Center, National Institutes of Health, Bethesda, MD, USA
| | - Harmen Reyngoudt
- NMR Laboratory, DRF, I2BM, MIRCen, Institute of Myology, Pitie-Salpetriere University Hospital and CEA, Paris, France
| | - Hirity Shimellis
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | | | - Eunhee Kim
- Office of Biostatistics, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Kenneth H Fischbeck
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Pierre G Carlier
- NMR Laboratory, DRF, I2BM, MIRCen, Institute of Myology, Pitie-Salpetriere University Hospital and CEA, Paris, France
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Andrade VLD, Kalva-Filho CA, Zagatto AM, Kaminagakura EI, Papoti M, Santiago PRP. Influência da aptidão aeróbia no running anaerobic sprint test (RAST). MOTRIZ: REVISTA DE EDUCACAO FISICA 2013. [DOI: 10.1590/s1980-65742013000700002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
O objetivo do estudo foi verificar a possível influência de diferentes níveis de aptidão aeróbia (VO2MAX) sobre os parâmetros do running anaerobic sprint test (RAST). Para isso, 38 indivíduos (Idade = 18,1±2,5 anos, Estatura = 173±1 cm e Massa corporal = 65,1±6,5 kg) foram classificados em dois grupos, baixa e elevada aptidão aeróbias (GBA: n=22 e GEA: n=16). O VO2MAX foi determinado por um esforço incremental em esteira rolante até a exaustão voluntária. O RAST foi composto de seis esforços máximos de 35m separados por 10s de intervalo passivo. O VO2MAX foi significativamente diferente entre os grupos (GBA = 51,7±1,9 mL.kg-1.min-1; GEA = 58,6±3,1 mL.kg-1.min-1). A potência média (PM) foi significativamente superior no grupo GBA (552,7±132,1 W) em relação ao grupo GEA (463,6±132,8 W). O impulso (ImP) foi significativamente correlacionado com o VO2MAX no GEA. Pode-se concluir que há um indicativo que o metabolismo aeróbio exerce uma influência na realização do RAST.
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Rizwan A, Serganova I, Khanin R, Karabeber H, Ni X, Thakur S, Zakian KL, Blasberg R, Koutcher JA. Relationships between LDH-A, lactate, and metastases in 4T1 breast tumors. Clin Cancer Res 2013; 19:5158-69. [PMID: 23833310 DOI: 10.1158/1078-0432.ccr-12-3300] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
PURPOSE To investigate the relationship between lactate dehydrogenase A (LDH-A) expression, lactate concentration, cell metabolism, and metastases in murine 4T1 breast tumors. EXPERIMENTAL DESIGN Inhibition of LDH-A expression and protein levels were achieved in a metastatic breast cancer cell line (4T1) using short hairpin RNA (shRNA) technology. The relationship between tumor LDH-A protein levels and lactate concentration (measured by magnetic resonance spectroscopic imaging, MRSI) and metastases was assessed. RESULTS LDH-A knockdown cells (KD9) showed a significant reduction in LDH-A protein and LDH activity, less acid production, decreased transwell migration and invasion, lower proliferation, reduced glucose consumption and glycolysis, and increase in oxygen consumption, reactive oxygen species (ROS), and cellular ATP levels, compared with control (NC) cells cultured in 25 mmol/L glucose. In vivo studies showed lower lactate levels in KD9, KD5, and KD317 tumors than in NC or 4T1 wild-type tumors (P < 0.01), and a linear relationship between tumor LDH-A protein expression and lactate concentration. Metastases were delayed and primary tumor growth rate decreased. CONCLUSIONS We show for the first time that LDH-A knockdown inhibited the formation of metastases, and was accompanied by in vivo changes in tumor cell metabolism. Lactate MRSI can be used as a surrogate to monitor targeted inhibition of LDH-A in a preclinical setting and provides a noninvasive imaging strategy to monitor LDH-A-targeted therapy. This imaging strategy can be translated to the clinic to identify and monitor patients who are at high risk of developing metastatic disease.
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Affiliation(s)
- Asif Rizwan
- Authors' Affiliations: Departments of Medical Physics, Neurology, Radiology, and Medicine, Bioinformatics Core, Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center; and Department of Physiology and Biophysics, Weill Cornell Graduate School of Medical Sciences, New York, New York
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12
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Carnosine: from exercise performance to health. Amino Acids 2013; 44:1477-91. [PMID: 23479117 DOI: 10.1007/s00726-013-1476-2] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Accepted: 02/16/2013] [Indexed: 12/27/2022]
Abstract
Carnosine was first discovered in skeletal muscle, where its concentration is higher than in any other tissue. This, along with an understanding of its role as an intracellular pH buffer has made it a dipeptide of interest for the athletic population with its potential to increase high-intensity exercise performance and capacity. The ability to increase muscle carnosine levels via β-alanine supplementation has spawned a new area of research into its use as an ergogenic aid. The current evidence base relating to the use of β-alanine as an ergogenic aid is reviewed here, alongside our current thoughts on the potential mechanism(s) to support any effect. There is also some emerging evidence for a potential therapeutic role for carnosine, with this potential being, at least theoretically, shown in ageing, neurological diseases, diabetes and cancer. The currently available evidence to support this potential therapeutic role is also reviewed here, as are the potential limitations of its use for these purposes, which mainly focusses on issues surrounding carnosine bioavailability.
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Ren J, Dean Sherry A, Malloy CR. Noninvasive monitoring of lactate dynamics in human forearm muscle after exhaustive exercise by (1)H-magnetic resonance spectroscopy at 7 tesla. Magn Reson Med 2012. [PMID: 23192863 DOI: 10.1002/mrm.24526] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Despite its importance in energy metabolism, lactate in human skeletal muscle has been difficult to detect by noninvasive (1)H-magnetic resonance spectroscopy mainly due to interference from large water and lipid signals. Long echo-time acquisitions at 7 T effectively attenuates the water and lipid signals in forearm muscle allowing direct observation of both lactate resonances, the methine at 4.09 ppm and the methyl at 1.31 ppm. Using this approach, we were able to monitor lactate dynamics at a temporal resolution of 32 s. While lactate was not detectable at rest, immediately after an acute period of exercise to fatigue the forearm muscle, lactate rose to a level comparable to that of creatine (∼30 mmol/kg wet weight). In a typical (1)H-magnetic resonance spectrum collected using a echo-time of 140 ms, the lactate methine and methyl resonances both appear as doublets with an unusually large splitting of ∼20 Hz due to residual dipolar coupling. During muscle recovery following exercise, the lactate signals decay rapidly with a time constant of t½ = 2.0 ± 0.6 min (n = 12 subjects). This fast and simple lactate detection method may prove valuable for monitoring lactate metabolism in cancer and in sports medicine applications.
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Affiliation(s)
- Jimin Ren
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA; Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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14
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Clinical significance of T2 mapping MRI for the evaluation of masseter muscle pain in patients with temporomandibular joint disorders. Oral Radiol 2012. [DOI: 10.1007/s11282-012-0108-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Sale C, Hill CA, Ponte J, Harris RC. β-alanine supplementation improves isometric endurance of the knee extensor muscles. J Int Soc Sports Nutr 2012; 9:26. [PMID: 22697405 PMCID: PMC3420321 DOI: 10.1186/1550-2783-9-26] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Accepted: 05/30/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND We examined the effect of four weeks of β-alanine supplementation on isometric endurance of the knee extensors at 45% maximal voluntary isometric contraction (MVIC). METHODS Thirteen males (age 23 ± 6 y; height 1.80 ± 0.05 m; body mass 81.0 ± 10.5 kg), matched for pre-supplementation isometric endurance, were allocated to either a placebo (n = 6) or β-alanine (n = 7; 6.4 g·d-1 over 4 weeks) supplementation group. Participants completed an isometric knee extension test (IKET) to fatigue, at an intensity of 45% MVIC, before and after supplementation. In addition, two habituation tests were completed in the week prior to the pre-supplementation test and a further practice test was completed in the week prior to the post-supplementation test. MVIC force, IKET hold-time, and impulse generated were recorded. RESULTS IKET hold-time increased by 9.7 ± 9.4 s (13.2%) and impulse by 3.7 ± 1.3 kN·s-1 (13.9%) following β-alanine supplementation. These changes were significantly greater than those in the placebo group (IKET: t(11) = 2.9, p ≤0.05; impulse: t(11) = 3.1, p ≤ 0.05). There were no significant changes in MVIC force in either group. CONCLUSION Four weeks of β-alanine supplementation at 6.4 g·d-1 improved endurance capacity of the knee extensors at 45% MVIC, which most likely results from improved pH regulation within the muscle cell as a result of elevated muscle carnosine levels.
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Affiliation(s)
- Craig Sale
- Biomedical, Life and Health Sciences Research Centre, Nottingham Trent University, Clifton Lane, Nottingham, NG11 8NS, UK.
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16
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Boer VO, Luijten PR, J. Klomp DW. Refocused double-quantum editing for lactate detection at 7 T. Magn Reson Med 2012; 69:1-6. [DOI: 10.1002/mrm.24227] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Revised: 01/13/2012] [Accepted: 02/06/2012] [Indexed: 12/24/2022]
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17
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Meyerspeer M, Robinson S, Nabuurs CI, Scheenen T, Schoisengeier A, Unger E, Kemp GJ, Moser E. Comparing localized and nonlocalized dynamic 31P magnetic resonance spectroscopy in exercising muscle at 7 T. Magn Reson Med 2012; 68:1713-23. [PMID: 22334374 PMCID: PMC3378633 DOI: 10.1002/mrm.24205] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Revised: 01/11/2012] [Accepted: 01/19/2012] [Indexed: 12/31/2022]
Abstract
By improving spatial and anatomical specificity, localized spectroscopy can enhance the power and accuracy of the quantitative analysis of cellular metabolism and bioenergetics. Localized and nonlocalized dynamic (31)P magnetic resonance spectroscopy using a surface coil was compared during aerobic exercise and recovery of human calf muscle. For localization, a short echo time single-voxel magnetic resonance spectroscopy sequence with adiabatic refocusing (semi-LASER) was applied, enabling the quantification of phosphocreatine, inorganic phosphate, and pH value in a single muscle (medial gastrocnemius) in single shots (T(R) = 6 s). All measurements were performed in a 7 T whole body scanner with a nonmagnetic ergometer. From a series of equal exercise bouts we conclude that: (a) with localization, measured phosphocreatine declines in exercise to a lower value (79 ± 7% cf. 53 ± 10%, P = 0.002), (b) phosphocreatine recovery shows shorter half time (t(1/2) = 34 ± 7 s cf. t(1/2) = 42 ± 7 s, nonsignificant) and initial postexercise phosphocreatine resynthesis rate is significantly higher (32 ± 5 mM/min cf. 17 ± 4 mM/min, P = 0.001) and (c) in contrast to nonlocalized (31)P magnetic resonance spectroscopy, no splitting of the inorganic phosphate peak is observed during exercise or recovery, just an increase in line width during exercise. This confirms the absence of contaminating signals originating from weaker-exercising muscle, while an observed inorganic phosphate line broadening most probably reflects variations across fibers in a single muscle.
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Affiliation(s)
- Martin Meyerspeer
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
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18
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Harris RC, Wise JA, Price KA, Kim HJ, Kim CK, Sale C. Determinants of muscle carnosine content. Amino Acids 2012; 43:5-12. [PMID: 22327512 PMCID: PMC3374101 DOI: 10.1007/s00726-012-1233-y] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Accepted: 01/23/2012] [Indexed: 01/05/2023]
Abstract
The main determinant of muscle carnosine (M-Carn) content is undoubtedly species, with, for example, aerobically trained female vegetarian athletes [with circa 13 mmol/kg dry muscle (dm)] having just 1/10th of that found in trained thoroughbred horses. Muscle fibre type is another key determinant, as type II fibres have a higher M-Carn or muscle histidine containing dipeptide (M-HCD) content than type I fibres. In vegetarians, M-Carn is limited by hepatic synthesis of β-alanine, whereas in omnivores this is augmented by the hydrolysis of dietary supplied HCD’s resulting in muscle levels two or more times higher. β-alanine supplementation will increase M-Carn. The same increase in M-Carn occurs with administration of an equal molar quantity of carnosine as an alternative source of β-alanine. Following the cessation of supplementation, M-Carn returns to pre-supplementation levels, with an estimated t1/2 of 5–9 weeks. Higher than normal M-Carn contents have been noted in some chronically weight-trained subjects, but it is unclear if this is due to the training per se, or secondary to changes in muscle fibre composition, an increase in β-alanine intake or even anabolic steroid use. There is no measureable loss of M-Carn with acute exercise, although exercise-induced muscle damage may result in raised plasma concentrations in equines. Animal studies indicate effects of gender and age, but human studies lack sufficient control of the effects of diet and changes in muscle fibre composition.
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Affiliation(s)
- R C Harris
- Junipa Ltd, Newmarket, Suffolk, CB8 8HD, UK.
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SALE CRAIG, SAUNDERS BRYAN, HUDSON SEAN, WISE JOHNA, HARRIS ROGERC, SUNDERLAND CAROLINED. Effect of β-Alanine Plus Sodium Bicarbonate on High-Intensity Cycling Capacity. Med Sci Sports Exerc 2011; 43:1972-8. [DOI: 10.1249/mss.0b013e3182188501] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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20
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Affiliation(s)
- Douglas E. Befroy
- Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, Connecticut
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
- Corresponding author: Douglas E. Befroy, , or Gerald I. Shulman,
| | - Gerald I. Shulman
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut
- Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut
- Corresponding author: Douglas E. Befroy, , or Gerald I. Shulman,
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Chang G, Wang L, Cárdenas-Blanco A, Schweitzer ME, Recht MP, Regatte RR. Biochemical and physiological MR imaging of skeletal muscle at 7 tesla and above. Semin Musculoskelet Radiol 2010; 14:269-78. [PMID: 20486034 DOI: 10.1055/s-0030-1253167] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Ultra-high field (UHF; >or=7 T) magnetic resonance imaging (MRI), with its greater signal-to-noise ratio, offers the potential for increased spatial resolution, faster scanning, and, above all, improved biochemical and physiological imaging of skeletal muscle. The increased spectral resolution and greater sensitivity to low-gamma nuclei available at UHF should allow techniques such as (1)H MR spectroscopy (MRS), (31)P MRS, and (23)Na MRI to be more easily implemented. Numerous technical challenges exist in the performance of UHF MRI, including changes in relaxation values, increased chemical shift and susceptibility artifact, radiofrequency (RF) coil design/B (1)(+) field inhomogeneity, and greater RF energy deposition. Nevertheless, the possibility of improved functional and metabolic imaging at UHF will likely drive research efforts in the near future to overcome these challenges and allow studies of human skeletal muscle physiology and pathophysiology to be possible at >or=7 T.
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Affiliation(s)
- Gregory Chang
- Department of Radiology, Center for Biomedical Imaging, New York University School of Medicine, New York, New York, 10016, USA.
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22
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Muscle LIM protein interacts with cofilin 2 and regulates F-actin dynamics in cardiac and skeletal muscle. Mol Cell Biol 2009; 29:6046-58. [PMID: 19752190 DOI: 10.1128/mcb.00654-09] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The muscle LIM protein (MLP) and cofilin 2 (CFL2) are important regulators of striated myocyte function. Mutations in the corresponding genes have been directly associated with severe human cardiac and skeletal myopathies, and aberrant expression patterns have often been observed in affected muscles. Herein, we have investigated whether MLP and CFL2 are involved in common molecular mechanisms, which would promote our understanding of disease pathogenesis. We have shown for the first time, using a range of biochemical and immunohistochemical methods, that MLP binds directly to CFL2 in human cardiac and skeletal muscles. The interaction involves the inter-LIM domain, amino acids 94 to 105, of MLP and the amino-terminal domain, amino acids 1 to 105, of CFL2, which includes part of the actin depolymerization domain. The MLP/CFL2 complex is stronger in moderately acidic (pH 6.8) environments and upon CFL2 phosphorylation, while it is independent of Ca(2+) levels. This interaction has direct implications in actin cytoskeleton dynamics in regulating CFL2-dependent F-actin depolymerization, with maximal depolymerization enhancement at an MLP/CFL2 molecular ratio of 2:1. Deregulation of this interaction by intracellular pH variations, CFL2 phosphorylation, MLP or CFL2 gene mutations, or expression changes, as observed in a range of cardiac and skeletal myopathies, could impair F-actin depolymerization, leading to sarcomere dysfunction and disease.
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23
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Bishop D, Edge J, Thomas C, Mercier J. Effects of high-intensity training on muscle lactate transporters and postexercise recovery of muscle lactate and hydrogen ions in women. Am J Physiol Regul Integr Comp Physiol 2008; 295:R1991-8. [PMID: 18832090 DOI: 10.1152/ajpregu.00863.2007] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The purpose of this study was to investigate the effects of high-intensity interval training (3 days/wk for 5 wk), provoking large changes in muscle lactate and pH, on changes in intracellular buffer capacity (betam(in vitro)), monocarboxylate transporters (MCTs), and the decrease in muscle lactate and hydrogen ions (H+) after exercise in women. Before and after training, biopsies of the vastus lateralis were obtained at rest and immediately after and 60 s after 45 s of exercise at 190% of maximal O2 uptake. Muscle samples were analyzed for ATP, phosphocreatine (PCr), lactate, and H+; MCT1 and MCT4 relative abundance and betam(in vitro) were also determined in resting muscle only. Training provoked a large decrease in postexercise muscle pH (pH 6.81). After training, there was a significant decrease in betam(in vitro) (-11%) and no significant change in relative abundance of MCT1 (96 +/- 12%) or MCT4 (120 +/- 21%). During the 60-s recovery after exercise, training was associated with no change in the decrease in muscle lactate, a significantly smaller decrease in muscle H+, and increased PCr resynthesis. These results suggest that increases in betam(in vitro) and MCT relative abundance are not linked to the degree of muscle lactate and H+ accumulation during training. Furthermore, training that is very intense may actually lead to decreases in betam(in vitro). The smaller postexercise decrease in muscle H+ after training is a further novel finding and suggests that training that results in a decrease in H+ accumulation and an increase in PCr resynthesis can actually reduce the decrease in muscle H+ during the recovery from supramaximal exercise.
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Affiliation(s)
- David Bishop
- School of Human Movement and Exercise Science, The University of Western Australia, Crawley, Western Australia, Australia.
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24
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Abstract
Magnetic resonance spectroscopy (MRS) of skeletal muscle has been successfully applied by physiologists over several decades, particularly for studies of high-energy phosphates (by (31)P-MRS) and glycogen (by (13)C-MRS). Unfortunately, the observation of these heteronuclei requires equipment that is typically not available on clinical MR scanners, such as broadband capability and a second channel for decoupling and nuclear Overhauser enhancement (NOE). On the other hand, (1)H-MR spectra of skeletal muscle can be acquired on many routine MR systems and also provide a wealth of physiological information. In particular, studies of intramyocellular lipids (IMCL) attract physiologists and endocrinologists because IMCL levels are related to insulin resistance and thus can lead to a better understanding of major health problems in industrial countries. The combination of (1)H-, (13)C-, and (31)P-MRS gives access to the major long- and short-term energy sources of skeletal muscle. This review summarizes the technical aspects and unique MR-methodological features of the different nuclei. It reviews clinical studies that employed MRS of one or more nuclei, or combinations of MRS with other MR modalities. It also illustrates that MR spectra contain additional physiological information that is not yet used in routine clinical applications.
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Affiliation(s)
- Chris Boesch
- Department of Clinical Research, MR-Spectroscopy and Methodology, University of Bern, Bern, Switzerland.
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25
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Prompers JJ, Jeneson JAL, Drost MR, Oomens CCW, Strijkers GJ, Nicolay K. Dynamic MRS and MRI of skeletal muscle function and biomechanics. NMR IN BIOMEDICINE 2006; 19:927-53. [PMID: 17075956 DOI: 10.1002/nbm.1095] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
MR is a powerful technique for studying the biomechanical and functional properties of skeletal muscle in vivo in health and disease. This review focuses on 31P, 1H and 13C MR spectroscopy for assessment of the dynamics of muscle metabolism and on dynamic 1H MRI methods for non-invasive measurement of the biomechanical and functional properties of skeletal muscle. The information thus obtained ranges from the microscopic level of the metabolism of the myocyte to the macroscopic level of the contractile function of muscle complexes. The MR technology presented plays a vital role in achieving a better understanding of many basic aspects of muscle function, including the regulation of mitochondrial activity and the intricate interplay between muscle fiber organization and contractile function. In addition, these tools are increasingly being employed to establish novel diagnostic procedures as well as to monitor the effects of therapeutic and lifestyle interventions for muscle disorders that have an increasing impact in modern society.
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Affiliation(s)
- Jeanine J Prompers
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, The Netherlands
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26
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Seiler S, Hetlelid KJ. The impact of rest duration on work intensity and RPE during interval training. Med Sci Sports Exerc 2006; 37:1601-7. [PMID: 16177614 DOI: 10.1249/01.mss.0000177560.18014.d8] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE To investigate the effect of rest duration on self-selected intensity, physiological responses, and RPE during a standardized, high-intensity interval training prescription. SUBJECTS Nine well-trained male runners (VO(2max) 71 +/- 4 mL.kg(-1).min(-1)) performed three treadmill interval training sessions running at constant 5% incline. Six 4-min work bouts with either 1-, 2-, or 4-min recovery periods were performed in each session. Sessions were prescribed as "high-intensity" workouts with the goal being to achieve the highest possible average running speed for the work intervals. Subjects regulated their work and rest intensity based on these instructions. In a fourth interval session, subjects self-selected recovery time in response to a fixed intensity. RESULTS Running velocity increased slightly (14.7 +/- 0.7 vs 14.4 +/- 0.8 km.h(-1), P = 0.02) when rest increased from 1 to 2 min, but showed no further increase with a 4-min rest (14.7 +/- 0.6 km.h(-1). Work VO(2) was slightly higher with a 2-min rest duration compared with 1 and 4 min (66.2 +/- 4.2 vs 65.1 +/- 4.2 and 64.9 +/- 4.7 mL.kg(-1).min(-1), P < 0.05). Peak blood lactate was similar (6.2 +/- 2.6, 6.8 +/- 2.9, 6.2 +/- 2.6 mmol.L(-1)) across conditions, whereas peak RPE was slightly lower during the 4-min rest condition (17.1 +/- 1.3, 17.7 +/- 1.5, 16.8 +/- 1.5, P < 0.05). With self-selected recovery time and no knowledge of elapsed time, the average rest duration was 118 +/- 23 s. CONCLUSIONS Under self-paced conditions, varying rest duration in a range of 1 to 4 min had limited impact on performance during repeated 4-min high-intensity exercise bouts. Approximately 120 s of active recovery may provide an appropriate balance between intracellular restitution and maintenance of high VO(2) on-kinetics.
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Affiliation(s)
- Stephen Seiler
- Faculty of Health and Sport, Agder University College, Kristiansand, Norway.
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27
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Yoshioka Y, Masuda T, Nakano H, Miura H, Nakaya S, Itazawa SI, Kubokawa M. In vitro 1H-NMR spectroscopic analysis of metabolites in fast- and slow-twitch muscles of young rats. Magn Reson Med Sci 2005; 1:7-13. [PMID: 16037662 DOI: 10.2463/mrms.1.7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The lactate (LAC), creatine (CRN), taurine (TAU), anserine (ANS) and carnosine (CAR) content of the masseter muscles (MM), long extensor muscles of digits (EDL) and soleus muscles (SOL) of young rats were determined using in vitro 1H-NMR spectroscopy to assess the significance of CRN, TAU, ANS and CAR in these muscles. The muscles of Wistar rats at the ages of 6, 12 and 18 weeks were dissected after decapitation and used for the metabolite analyses. The LAC and CAR content of all muscle groups showed no age dependence. The CRN content was increased age-dependently in MM but not in EDL or SOL. The LAC and CRN content was higher in MM and EDL (fast-twitch) than in SOL (slow-twitch) (P<0.01-0.001 at 18 weeks). A significant positive correlation existed between the LAC and CRN content (P<0.00001, r=0.80), suggesting that the CRN content reflects the capacity of the anaerobic glycolysis of the individual muscles. The TAU content was higher in SOL and MM than in EDL (P<0.05) and showed an approximately 1.5-fold increase with age in all three muscle groups. The ANS content was higher in EDL than in SOL and MM (P<0.001), and showed an approximately threefold increase with age in all three muscle groups. The ANS content positively correlated with the LAC content (P<0.001, r=0.41), and the chemical shift of the imidazole proton in ANS showed a correlation with the LAC content (P<0.0001, r>0.76), indicating that ANS would buffer the pH change produced by LAC. These results suggest that 1H-NMR spectroscopy would provide an adjunct method of assessing the muscle types and their development.
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Affiliation(s)
- Yoshichika Yoshioka
- Department of Physiology II, School of Medicine, Iwate Medical University, Morioka, Japan.
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28
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Price TB, Kamen G, Damon BM, Knight CA, Applegate B, Gore JC, Eward K, Signorile JF. Comparison of MRI with EMG to study muscle activity associated with dynamic plantar flexion. Magn Reson Imaging 2004; 21:853-61. [PMID: 14599535 DOI: 10.1016/s0730-725x(03)00183-8] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This study compared magnetic resonance imaging (MRI) and surface electromyography (EMG) to evaluate the effect of knee angle upon plantar flexion activity in the triceps surae muscles [medial & lateral gastrocnemius (MG, LG) and the soleus (SOL)]. Two weight & height matched groups performed identical protocols, twelve (6M, 6F) in the MRI group, twelve (8M, 4F) in the EMG group. Subjects plantar flexed dynamically for 2 min at 25% of 1-repetition maximum voluntary contraction (1-RM). Exercise was performed with the knee extended (0 degrees flexion), flexed (90 degrees ), and partially flexed (45 degrees ). In the MRI group spin-echo images were acquired before and immediately following each exercise session. T(2) times, calculated at rest and after exercise by fitting the echoes to a monoexponential decay pattern with a least-squares algorithm, were compared with EMG data. In the EMG group a bipolar electrode was used to collect samples were from the MG, LG, SOL, and anterior tibialis (TA) during exercise at each knee angle, MRI also examined the peroneus (PER). At 0 degrees flexion MRI demonstrated a significant post-exercise T(2) increase in the MG (p < or = 0.001), LG (p < or = 0.001), and PER (p < or = 0.01), with no T(2) change in the SOL or TA. At 90 degrees flexion there was a significant T(2) increase in the SOL (p < or = 0.001) with no significant T(2) change in the MG, LG, PER, or TA. At 45 degrees T(2) increased significantly in the SOL (p < or = 0.001) and LG (p < or = 0.05), but not the MG, PER, or TA. EMG produced similar results with the exception that there was significant activity in the TA during the relaxation cycle of the 90 degrees protocol. We conclude that: 1) Soleus activity is measurable by MRI; and 2) MRI and EMG produce similar results from different physiological sources, and are therefore complementary tools for evaluating muscle activity.
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Affiliation(s)
- Thomas B Price
- Yale University School of Medicine, Department of Diagnostic Radiology, New Haven, CT 06510, USA.
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29
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Schrauwen-Hinderling VB, van Loon LJC, Koopman R, Nicolay K, Saris WHM, Kooi ME. Intramyocellular lipid content is increased after exercise in nonexercising human skeletal muscle. J Appl Physiol (1985) 2003; 95:2328-32. [PMID: 12923116 DOI: 10.1152/japplphysiol.00304.2003] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Intramyocellular lipid (IMCL) content has been reported to decrease after prolonged submaximal exercise in active muscle and, therefore, seems to form an important local substrate source. Because exercise leads to a substantial increase in plasma free fatty acid (FFA) availability with a concomitant increase in FFA uptake by muscle tissue, we aimed to investigate potential differences in the net changes in IMCL content between contracting and noncontracting skeletal muscle after prolonged endurance exercise. IMCL content was quantified by magnetic resonance spectroscopy in eight trained cyclists before and after a 3-h cycling protocol (55% maximal energy output) in the exercising vastus lateralis and the nonexercising biceps brachii muscle. Blood samples were taken before and after exercise to determine plasma FFA, glycerol, and triglyceride concentrations, and substrate oxidation was measured with indirect calorimetry. Prolonged endurance exercise resulted in a 20.4 +/- 2.8% (P < 0.001) decrease in IMCL content in the vastus lateralis muscle. In contrast, we observed a substantial (37.9 +/- 9.7%; P < 0.01) increase in IMCL content in the less active biceps brachii muscle. Plasma FFA and glycerol concentrations were substantially increased after exercise (from 85 +/- 6 to 1450 +/- 55 and 57 +/- 11 to 474 +/- 54 microM, respectively; P < 0.001), whereas plasma triglyceride concentrations were decreased (from 1498 +/- 39 to 703 +/- 7 microM; P < 0.001). IMCL is an important substrate source during prolonged moderate-intensity exercise and is substantially decreased in the active vastus lateralis muscle. However, prolonged endurance exercise with its concomitant increase in plasma FFA concentration results in a net increase in IMCL content in less active muscle.
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30
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Damon BM, Hsu AC, Stark HJ, Dawson MJ. The carnosine C-2 proton's chemical shift reports intracellular pH in oxidative and glycolytic muscle fibers. Magn Reson Med 2003; 49:233-40. [PMID: 12541242 DOI: 10.1002/mrm.10384] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The appearance of new peaks in the 7.7-8.6 and 6.8-7.4 ppm regions of the postexercise (1)H spectrum of frog muscle is reported. These new peaks result from the splitting of single pre-exercise carnosine C-2 and C-4 peaks into two peaks, representing the intracellular pH (pH(I)) of oxidative and glycolytic fibers. The following data support this conclusion: 1) comparison of means and regression analysis indicates equivalence of the pH(I) measurements by (1)H and (31)P NMR; 2) the pre- and poststimulation concentrations of carnosine are equal; 3) in ischemic rat hindlimb muscles, the presence of a single, more acidic peak in the plantaris; a single, less acidic peak in the soleus; and two peaks (more and less acidic) in the gastrocnemius correspond to published values for the fiber-type composition of these muscles; and 4) in muscles treated with iodoacetate prior to and during stimulation, a second peak never appears. These data indicate that it is feasible to measure separately the pH(I) of oxidative and glycolytic fibers using (1)H NMR spectroscopy.
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Affiliation(s)
- Bruce M Damon
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana-Champaign, Illinois, USA.
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31
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Hu J, Jiang Q, Xia Y, Zuo C. High spatial resolution in vivo 2D (1)H magnetic resonance spectroscopic imaging of human muscles with a band-selective technique. Magn Reson Imaging 2001; 19:1091-6. [PMID: 11711233 DOI: 10.1016/s0730-725x(01)00438-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
This report demonstrates a 2D (1)H magnetic resonance spectroscopic imaging (MRSI) technique that can address some technical difficulties often encountered in MRS studies of human muscles. A preliminary application of this whole-slice technique in human skeletal muscles demonstrates clearly noticeable differences in (1)H metabolite spectra between different human muscles. This observation illustrates the importance of multi-voxel and high spatial resolution in a heterogeneous environment. This technique is robust, can be easily implemented on a commercial MR scanner, and should prove useful for investigators in both basic and clinical (1)H MRS studies.
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Affiliation(s)
- J Hu
- Department of Radiology, Wayne State University, Detroit, MI 48201, USA.
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Kemp GJ, Roussel M, Bendahan D, Le Fur Y, Cozzone PJ. Interrelations of ATP synthesis and proton handling in ischaemically exercising human forearm muscle studied by 31P magnetic resonance spectroscopy. J Physiol 2001; 535:901-28. [PMID: 11559784 PMCID: PMC2278815 DOI: 10.1111/j.1469-7793.2001.00901.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2000] [Accepted: 05/14/2001] [Indexed: 11/26/2022] Open
Abstract
1. In ischaemic exercise ATP is supplied only by glycogenolysis and net splitting of phosphocreatine (PCr). Furthermore, 'proton balance' involves only glycolytic lactate/H+ generation and net H+ 'consumption' by PCr splitting. This work examines the interplay between these, metabolic regulation and the creatine kinase equilibrium. 2. Nine male subjects (age 25-45 years) performed finger flexion (7 % maximal voluntary contraction at 0.67 Hz) under cuff ischaemia. 31P magnetic resonance spectra were acquired from finger flexor muscle in a 4.7 T magnet using a 5 cm surface coil. 3. Initial PCr depletion rate estimates total ATP turnover rate; glycolytic ATP synthesis was obtained from this and changes in [PCr], and then used to obtain flux through 'distal' glycolysis (phosphofructokinase and beyond) to lactate; 'proximal' flux (through phosphorylase) was obtained from this and changes in [phosphomonoester]. Total H+ load (lactate load less H+ consumption) was used to estimate cytosolic buffer capacity (beta). 4. Glycolytic ATP synthesis increased from near zero while PCr splitting declined. Net H+ load was approximately linear with pH, suggesting beta = 20 mmol x l(-1) (pH unit)(-1) at rest, increasing as pH falls. 5. Relationships between glycolytic rate and changes in [PCr] (i.e. the time-integrated mismatch between ATP use and production), and thus also [P(i)] (substrate for phosphorylase), suggest that increase in glycolysis is due partly to 'open-loop' Ca2+-dependent conversion of phosphorylase b to a, and partly to the 'closed loop' increase in P(i) consequent on net PCr splitting. 6. The 'settings' of these mechanisms have a strong influence on changes in pH and metabolite concentrations.
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Affiliation(s)
- G J Kemp
- Department of Musculoskeletal Science, University of Liverpool, Liverpool L69 3GA, UK.
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Affiliation(s)
- I Shrier
- Department of Physiology, McGill University, Centre for Clinical Epidemiology and Community Studies, Lady Davis Institute for Medical Research, SMBD-Jewish General Hospital, Montreal, Quebec, Canada
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Affiliation(s)
- T B Price
- Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, CT 06510, USA
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Medbø JI, Hanem S, Noddeland H, Jebens E. Arterio-venous differences of blood acid-base status and plasma sodium caused by intense bicycling. ACTA PHYSIOLOGICA SCANDINAVICA 2000; 168:311-26. [PMID: 10712569 DOI: 10.1046/j.1365-201x.2000.00650.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
After intense exercise muscle may give off hydrogen ions independently of lactate, perhaps by a mechanism involving sodium ions. To examine this possibility further five healthy young men cycled for 2 min to exhaustion. Blood was drawn from catheters in the femoral artery and vein during exercise and at 1-h intervals after exercise. The blood samples were analysed for pH, blood gases, lactate, haemoglobin, and plasma proteins and electrolytes. Base deficit was calculated directly without using common approximations. The leg blood flow was also measured, thus allowing calculations of the leg's exchange of metabolites. The arterial blood lactate concentration rose to 14.2 +/- 1.0 mmol L-1, the plasma pH fell to 7. 18 +/- 0.02, and the base deficit rose 22% more than the blood lactate concentration did. The femoral-venous minus arterial differences peaked at 1.8 +/- 0.2 mmol L-1 (lactate), -0.24 +/- 0.01 (pH), and 4.5 +/- 0.4 mmol L-1 (base deficit), and -2.5 +/- 0.7 mmol L-1 (plasma sodium concentration corrected for volume changes). Thus, near the end of the exercise and for the first 10 min of the recovery period the leg gave off more hydrogen ions than lactate ions to the blood, and sodium left plasma in proportion to the extra hydrogen ions appearing. The leg's integrated excess release of hydrogen ions of 0.88 +/- 0.45 mmol kg-1 body mass was 67% of the integrated lactate release. Base deficit calculated by the traditional approximate equations underestimated the true value, but the error was less than 10%. We conclude that intense exercise and lactic acidosis may lead to a muscle release of hydrogen ions independent of lactate release, possibly by a Na+,H+ exchange. Hydrogen ions were largely buffered in the red blood cells.
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Affiliation(s)
- J I Medbø
- National Institute of Occupational Health, POB 8149 dep., Oslo, Norway
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Boesch C, Décombaz J, Slotboom J, Kreis R. Observation of intramyocellular lipids by means of 1H magnetic resonance spectroscopy. Proc Nutr Soc 1999; 58:841-50. [PMID: 10817151 DOI: 10.1017/s0029665199001147] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) are being increasingly used for investigations of human muscle physiology. While MRI reveals the morphology of muscles in great detail (e.g. for the determination of muscle volumes), MRS provides information on the chemical composition of the tissue. Depending on the observed nucleus, MRS allows the monitoring of high-energy phosphates (31P MRS), glycogen (13C MRS), or intramyocellular lipids (1H MRS), to give only a few examples. The observation of intramyocellular lipids (IMCL) by means of 1H MRS is non-invasive and, therefore, can be repeated many times and with a high temporal resolution. MRS has the potential to replace the biopsy for the monitoring of IMCL levels; however, the biopsy still has the advantage that other methods such as those used in molecular biology can be applied to the sample. The present study describes variations in the IMCL levels (expressed in mmol/kg wet weight and ml/100 ml) in three different muscles before and after (0, 1, 2, and 5 d) marathon runs for a well-trained individual who followed two different recovery protocols varying mainly in the diet. It was shown that the repletion of IMCL levels is strongly dependent on the diet post exercise. The monitoring of IMCL levels by means of 1H MRS is extremely promising, but several methodological limitations and pitfalls need to be considered, and these are addressed in the present review.
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Affiliation(s)
- C Boesch
- Department of Clinical Research, MR Spectroscopy and Methodology, University of Bern, Switzerland.
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Kreis R, Jung B, Rotman S, Slotboom J, Boesch C. Non-invasive observation of acetyl-group buffering by 1H-MR spectroscopy in exercising human muscle. NMR IN BIOMEDICINE 1999; 12:471-476. [PMID: 10654294 DOI: 10.1002/(sici)1099-1492(199911)12:7<471::aid-nbm591>3.0.co;2-a] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The observation of a previously unidentified peak in localized 1H magnetic resonance (MR) spectra of human muscle during and after a work load is reported. Basic NMR properties of this resonance, as well as physiologic circumstances of its observation, suggest that it is due to the acetyl group of acetylcarnitine. The relatively large pool of muscular carnitine acts as a buffering system stabilizing the ratio of acetylated to free coenzyme A. Free carnitine can be acetylated to a large extent whenever a mismatch occurs between the fluxes through pyruvate dehydrogenase and the TCA cycle. Results of initial applications of 1H MR spectroscopy in several muscles and under different exercise regimens are in agreement with earlier invasive measurements of acetylcarnitine. It is demonstrated that the detailed dynamics of acetyl group formation are now likely to be observable non-invasively in humans by localized 1H magnetic resonance spectroscopy on standard MR imaging systems, and that acetylcarnitine buffering as a function of exercise type, oxygenation states, diet and pathology could thus be studied repeatedly and in various muscle groups with much improved temporal resolution.
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Affiliation(s)
- R Kreis
- Department of Clinical Research, University of Bern, Switzerland.
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Walter G, Vandenborne K, Elliott M, Leigh JS. In vivo ATP synthesis rates in single human muscles during high intensity exercise. J Physiol 1999; 519 Pt 3:901-10. [PMID: 10457099 PMCID: PMC2269548 DOI: 10.1111/j.1469-7793.1999.0901n.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
1. In vivo ATP synthesis rates were measured in the human medial gastrocnemius muscle during high intensity exercise using localized 31P-magnetic resonance spectroscopy (31P-MRS). Six-second localized spectra were acquired during and following a 30 s maximal voluntary rate exercise using a magnetic resonance image-guided spectral localization technique. 2. During 30 s maximal voluntary rate exercise, ATPase fluxes were predominantly met by anaerobic ATP sources. Maximal in vivo glycogenolytic rates of 207 +/- 48 mM ATP min-1 were obtained within 15 s, decreasing to 72 +/- 34 mM ATP min-1 by the end of 30 s. In contrast, aerobic ATP synthesis rates achieved 85 +/- 2 % of their maximal capacity within 9 s and did not change throughout the exercise. The ratio of peak glycolytic ATP synthesis rate to maximal oxidative ATP synthesis was 2.9 +/- 0.9. 3. The non-Pi, non-CO2 buffer capacity was calculated to be 27.0 +/- 6. 2 slykes (millimoles acid added per unit change in pH). At the cessation of exercise, Pi, phosphomonoesters and CO2 were predicted to account for 17.2 +/- 1.5, 5.57 +/- 0.97 and 2.24 +/- 0.34 slykes of the total buffer capacity. 4. Over the approximately linear range of intracellular pH recovery following the post-exercise acidification, pHi recovered at a rate of 0.19 +/- 0.03 pH units min-1. Proton transport capacity was determined to be 16.4 +/- 4.1 mM (pH unit)-1 min-1 and corresponded to a maximal proton efflux rate of 15.3 +/- 2.7 mM min-1. 5. These data support the observation that glycogenolytic and glycolytic rates are elevated in vivo in the presence of elevated Pi levels. The data do not support the hypothesis that glycogenolysis follows Michealis-Menten kinetics with an apparent Km for [Pi] in vivo. 6. In vivo -measured ATP utilization rates and the initial dependence on PCr and glycolysis were similar to those previously reported in in situ studies involving short duration, high intensity exercise. This experimental approach presents a non-invasive, quantitative measure of peak glycolytic rates in human skeletal muscle.
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Affiliation(s)
- G Walter
- Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104-6021, USA.
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Abstract
Magnetic resonance imaging (MRI) is a well known diagnostic tool in radiology that produces unsurpassed images of the human body, in particular of soft tissue. However, the medical community is often not aware that MRI is an important yet limited segment of magnetic resonance (MR) or nuclear magnetic resonance (NMR) as this method is called in basic science. The tremendous morphological information of MR images sometimes conceal the fact that MR signals in general contain much more information, especially on processes on the molecular level. NMR is successfully used in physics, chemistry, and biology to explore and characterize chemical reactions, molecular conformations, biochemical pathways, solid state material, and many other applications that elucidate invisible characteristics of matter and tissue. In medical applications, knowledge of the molecular background of MRI and in particular MR spectroscopy (MRS) is an inevitable basis to understand molecular phenomenon leading to macroscopic effects visible in diagnostic images or spectra. This review shall provide the necessary background to comprehend molecular aspects of magnetic resonance applications in medicine. An introduction into the physical basics aims at an understanding of some of the molecular mechanisms without extended mathematical treatment. The MR typical terminology is explained such that reading of original MR publications could be facilitated for non-MR experts. Applications in MRI and MRS are intended to illustrate the consequences of molecular effects on images and spectra.
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Affiliation(s)
- C Boesch
- Department of Clinical Research, University of Bern, Switzerland
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Binzoni T, Colier W, Hiltbrand E, Hoofd L, Cerretelli P. Muscle O(2) consumption by NIRS: a theoretical model. J Appl Physiol (1985) 1999; 87:683-8. [PMID: 10444628 DOI: 10.1152/jappl.1999.87.2.683] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In the past, the measurement of O(2) consumption ((2)) by the muscle could be carried out noninvasively by near-infrared spectroscopy from oxyhemoglobin and/or deoxyhemoglobin measurements only at rest or during steady isometric contractions. In the present study, a mathematical model is developed allowing calculation, together with steady-state levels of (2), of the kinetics of (2) readjustment in the muscle from the onset of ischemic but aerobic constant-load isotonic exercises. The model, which is based on the known sequence of exoergonic metabolic pathways involved in muscle energetics, allows simultaneous fitting of batched data obtained during exercises performed at different workloads. A Monte Carlo simulation has been carried out to test the quality of the model and to define the most appropriate experimental approach to obtain the best results. The use of a series of experimental protocols obtained at different levels of mechanical power, rather than repetitions of the same load, appears to be the most suitable procedure.
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Affiliation(s)
- T Binzoni
- Departments of Physiology and Radiology, Faculty of Medicine, University of Geneva, 1211 Geneva 4, Switzerland.
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Kreis R, Jung B, Slotboom J, Felblinger J, Boesch C. Effect of exercise on the creatine resonances in 1H MR spectra of human skeletal muscle. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 1999; 137:350-357. [PMID: 10089169 DOI: 10.1006/jmre.1998.1683] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
1H MR spectra of human muscles were recorded before, during, and after fatiguing exercise. In contrast to expectations, it was found that the spectral contributions of creatine/phosphocreatine (Cr/PCr) were subject to change as a function of exercise. In particular, the dipolar-coupled methylene protons of Cr/PCr were found to be reduced in intensity in proportion to the co-registered PCr levels. Recovery after exercise and behavior under ischemic conditions provide further evidence to suggest that the contributions of the CH2 protons of Cr/PCr to 1H MR spectra of human muscle in vivo reflect PCr rather than Cr levels. Variation of experimental parameters showed that this effect is not due to a trivial change in relaxation times. At present it can only be speculated about why the Cr resonances have reduced NMR visibility. If temporary binding to macromolecules should be involved, the free Cr concentration-important for equilibrium calculations of the creatine kinase reaction-might be different from what was previously assumed.
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Affiliation(s)
- R Kreis
- Unit for Magnetic Resonance Spectroscopy and Methodology, University Bern, Bern, CH-3010, Switzerland
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Abstract
To elucidate the low proton nuclear magnetic resonance (NMR) visibility of muscle lactate previously demonstrated in excised rat muscle, lactate transverse relaxation was investigated in the same model using double quantum editing sequences with effective echo times ranging from 55 to 475 msec. On this time scale, muscle lactate clearly exhibits a bi-exponential transverse relaxation with a short T2 of 33+/-5 msec (mean +/- SE, n = 3) and a long T2 of 230+/-10 msec. The relative populations (84+/-4% vs. 16+/-4%, respectively) of these two lactate pools are compatible with compartmentation between intra- and extracellular muscle lactate.
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Affiliation(s)
- L Jouvensal
- CEA, Service Hospitalier Frédéric Joliot, Département de Recherche Médicale, Orsay, France
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Quinn PJ, Boldyrev AA, Formazuyk VE. Carnosine: its properties, functions and potential therapeutic applications. Mol Aspects Med 1998; 13:379-444. [PMID: 9765790 DOI: 10.1016/0098-2997(92)90006-l] [Citation(s) in RCA: 213] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Carnosine and related dipeptides such as anserine are naturally-occurring histidine-containing compounds. They are found in several tissues most notably in muscle where they represent an appreciable fraction of the total water-soluble nitrogen-containing compounds. The biological role of these dipeptides are conjectural but they are believed to act as cytosolic buffering agents. Numerous studies have demonstrated, both at the tissue and organelle level, that they possess strong and specific antioxidant properties. Carnosine and related dipeptides have been shown to prevent peroxidation of model membrane systems leading to the suggestion that they represent water-soluble counterparts to lipid-soluble antioxidants such as alpha-tocopherol in protecting cell membranes from oxidative damage. Other roles ascribed to these dipeptides include actions as neurotransmitters, modulation of enzymic activities and chelation of heavy metals. Many claims have been made in respect of therapeutic actions of carnosine and histidine-containing dipeptides. These include antihypertensive effects, actions as immunomodulating agents, wound healing and antineoplastic effects. Many of these claims have not been convincingly documented nor subject to rigorous clinical evaluation. Nevertheless, there are examples where studies have shown considerable promise. One is the treatment of senile cataract in dogs and another is in acceleration of healing of surface wounds and burns to the skin. It is clear from this review that many of the effects of these histidine-containing dipeptides, especially in regard to claims for their therapeutic effects, need to be subjected to critical experimental and clinical examination. Several applications do, however, show clear evidence of being useful therapeutic agents.
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Affiliation(s)
- P J Quinn
- Biochemistry Department, King's College London, U.K
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PRICE THOMASB, KENNAN RICHARDP, GORE JOHNC. Isometric and dynamic exercise studied with echo planar magnetic resonance imaging (MRI). Med Sci Sports Exerc 1998. [DOI: 10.1249/00005768-199809000-00006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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45
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Price TB, Kennan RP, Gore JC. Isometric and dynamic exercise studied with echo planar magnetic resonance imaging (MRI). Med Sci Sports Exerc 1998; 30:1374-80. [PMID: 9741606 DOI: 10.1097/00005768-199809000-00006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE The effect of different types of exercise upon echo planar (EP) magnetic resonance (MR) images was examined during and after both dynamic and isometric dorsi-flexion exercises at matched workloads and durations. METHODS Healthy untrained subjects performed either dynamic exercise through a full range of motion and against a constant resistance or isometric exercise at the center of the range of motion and against a constant resistance at 25 or 70% their measured maximum voluntary contraction (MVC). EP MR images were acquired at 1.5 T every 4 s before (4 images), during (27 images), and after (29-65 images) exercise. A spin echo EP sequence was employed with TE = 30 ms, TR = 4000 ms, FOV = 20 x 40 cm, 64 x 128 matrix. The changes in proton transverse relaxation rate (deltaR2, [s(-1)]) relative to values obtained before exercise were calculated from individual images at different times during and after exercise. RESULTS At both 70 and 25% of MVC, the maximum deltaR2 after dynamic exercise (-8.38+/-0.32 s(-1) (70%), -6.47+/-1.23s(-1) (25%)) was significantly greater (P < or = 0.05) than after isometric exercise (-5.91+/-0.67 s(-1) (70%), -3.80+/-0.87s(-1) (25%)). Throughout the period that recovery was monitored, the recovery patterns of deltaR2 following isometric and dynamic exercise at both workloads remained parallel. CONCLUSIONS We conclude that exercise-induced changes in MR images are influenced not only by workload and exercise duration but also by the type of exercise, and we postulate that these differences result from the different physiological responses elicited by the different types of exercise.
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Affiliation(s)
- T B Price
- Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, CT 06510, USA.
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Price TB, Gore JC. Effect of muscle glycogen content on exercise-induced changes in muscle T2 times. J Appl Physiol (1985) 1998; 84:1178-84. [PMID: 9516182 DOI: 10.1152/jappl.1998.84.4.1178] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Effects of gastrocnemius glycogen (Gly) concentration on changes in transverse relaxation time (T2; ms) were studied after 5-min plantar flexion at 25% of maximum voluntary contraction (MVC). Gastrocnemius Gly, phosphorus metabolites, and T2 were measured in seven subjects by using interleaved 13C/31P magnetic resonance spectroscopy (MRS) at 4.7 T and magnetic resonance imaging (MRI; 1.5 T). After baseline MRS/MRI, subjects exercised for 5 min at 25% of MVC and were reexamined (MRS/MRI). Subjects then performed approximately 15 min of single-leg toe raises (50 +/- 2% of MVC), depleting gastrocnemius Gly by 43%. After a 1-h rest (for T2 return to baseline), subjects repeated the 5-min protocol, followed by a final MRI/MRS. After the initial 5-min protocol, T2 values increased by 5.9 +/- 0.8 ms (29.9 +/- 0.4 to 35.8 +/- 0.6 ms), whereas Gly did not change significantly (70.5 +/- 6.8 to 67.6 +/- 7.4 mM). After 15 min of toe raises, gastrocnemius Gly was reduced to 40.4 +/- 5.3 mM (P </= 0. 01), recovering to 45.8 +/- 5.3 mM (P </= 0.05) during a 1-h rest. After the second 5-min bout of plantar flexion (reduced Gly at 25% of MVC), T2 values increased by 5.0 +/- 0.8 ms (30.4 to 35.4 ms), whereas muscle Gly rose to 57.6 +/- 5.3 mM. We conclude that muscle Gly concentration per se does not affect exercise-induced T2 increases in the human gastrocnemius.
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Affiliation(s)
- T B Price
- Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, Connecticut 06510, USA.
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Hunjan S, Mason RP, Mehta VD, Kulkarni PV, Aravind S, Arora V, Antich PP. Simultaneous intracellular and extracellular pH measurement in the heart by 19F NMR of 6-fluoropyridoxol. Magn Reson Med 1998; 39:551-6. [PMID: 9543416 DOI: 10.1002/mrm.1910390407] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
6-Fluoropyridoxol (6-FPOL) was evaluated as a simultaneous indicator of intracellular and extracellular pH and, hence, pH gradient in perfused rat hearts. After infusion, 19F NMR spectra rapidly showed two well-resolved peaks assigned to the intracellular and extracellular compartments, and pH was calculated on the basis of chemical shift with respect to a sodium trifluoroacetate standard. To demonstrate use of this molecule, dynamic changes in myocardial pH were assessed with a time resolution of 2 min during respiratory and metabolic alkalosis or acidosis and ischemia. For a typical heart, intracellular pH (pHi) = 7.14+/-0.01 and extracellular pH (pHe) = 7.52+/-0.02. In response to metabolic alkalosis, pHi remained relatively constant and the pH gradient increased. In contrast, respiratory challenge caused a significant increase in pHi. Independent measurements using pH electrodes and 31P NMR confirmed validity of the 19F NMR results.
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Affiliation(s)
- S Hunjan
- Advanced Radiological Sciences, UT Southwestern Medical Center, Dallas, Texas 75235-9058, USA
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Abstract
In most cell types, including resting skeletal muscle fibers, internal pH (pHi) is kept constant at a relatively alkaline level. The high pHi is obtained in spite of a chronic acid load resulting from cellular metabolism and passive influx of protons driven by electrochemical forces. Regulation of pHi depends on continuous activity of membrane transport systems that mediate an outflux of H+ (or bicarbonate influx), whereby the acid load is counterbalanced. The transporters involved in muscle pH regulation at rest are the Na+/H+ exchange system as well as the Na+-dependent and Na+-independent Cl- bicarbonate transport systems. The Na+/H+ exchanger seems to be active at resting pHi levels in skeletal muscle. Therefore, pH homeostasis in skeletal muscle most likely involves an equilibrium between counter-directed H+ fluxes. A minor fraction of H+ release during intense exercise is mediated by the Na+/H+ exchanger. The capacity of this system is increased with training and hypoxia in rat skeletal muscle. The dominant acid extruding system associated with intense exercise is the lactate/H+ co-transporter. It has been demonstrated that the capacity of the lactate/H+ co-transporter of rat skeletal muscle is upregulated with training and chronic electrical stimulation, and that it is reduced upon denervation and hindlimb unweighting. Moreover, athletes can have an elevated lactate/H+ co-transport capacity, whereas the thigh muscle of spinal cord-injured individuals has a lower transport capacity than the one of healthy untrained subjects. Thus, it appears that the capacity of the lactate/H+ transporter is affected by the level of muscle activity in both rats and humans. In addition, the rate of H+ release from muscle may also be influenced by capillarization and local blood flow. Finally the resulting pH displacement during acid accumulation is determined by the cellular buffer capacity, which may also undergo adaptive changes.
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Affiliation(s)
- C Juel
- Copenhagen Muscle Research Centre, August Krogh Institute, University of Copenhagen, Denmark
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49
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Jouvensal L, Carlier PG, Bloch G. Low visibility of lactate in excised rat muscle using double quantum proton spectroscopy. Magn Reson Med 1997; 38:706-11. [PMID: 9358443 DOI: 10.1002/mrm.1910380505] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Lactate NMR visibility was investigated in excised rat muscle at 3 T by comparing the concentration determined in situ by double quantum (DQ) proton spectroscopy (150 ms effective echo time) to the concentration measured in vitro from perchloric acid extracts of the same muscle samples. After 1-2 h of ischemia, lactate NMR visibility was 32 +/- 3% (+/- SE, n = 9), and was only 21 +/- 1% (n = 6) after 10-12 h. Muscle lactate T2 was 140 +/- 11 ms and 184 +/- 6 ms, respectively. All potential mechanisms of DQ lactate signal attenuation (B0 and B1 inhomogeneity, DQ transverse relaxation, diffusion) were examined, and accounted for when necessary. A significant increase in lactate NMR visibility was demonstrated using a shorter effective echo time (79 ms) DQ editing sequence. These results are interpreted as reflecting muscle lactate compartmentation between a long T2 pool predominantly detected by DQ spectroscopy, and a short T2 pool virtually invisible with longer echo time NMR techniques.
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Affiliation(s)
- L Jouvensal
- CEA, Service Hospitalier Frédéric Joliot, Département de Recherche Médicale, Orsay, France
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50
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Kemp GJ. Physiological constraints on changes in pH and phosphorus metabolite concentrations in ischemically exercising muscle: implications for metabolic control and for the interpretation of 31P-magnetic resonance spectroscopic studies. MAGMA (NEW YORK, N.Y.) 1997; 5:231-41. [PMID: 9351027 DOI: 10.1007/bf02594586] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Relationships between pH and the concentrations of phosphocreatine (PCr), inorganic phosphate (Pi), and lactate during ischemic exercise depend on passive buffering, proton consumption as a consequence of net PCr breakdown, the control of glycogenolysis, (particularly in relation to the concentration of Pi, a substrate of glycogen phosphorylase that is produced by net PCr breakdown), and the creatine kinase equilibrium. The author analyzes the implications of these relationships for the interpretation of 31P-magnetic resonance spectroscopic data and for the control of glycogenolysis. For realistic adenosine diphosphate (ADP) concentrations, given the constraints of the creatine kinase equilibrium, the pH must be near-linear with lactate, with an apparent buffer capacity (i.e., the ratio of lactate accumulation to pH change) that is nearly twice the true buffer capacity (i.e., the ratio of net proton loading to pH change). The implications for glycogenolytic control depend on adenosine triphosphate (ATP) turnover, but an upper limit of activation of glycogen phosphorylase (i.e., the amount of the a form) that would permit no increase in ADP concentration can be calculated. Phosphorylase activation during ischemic exercise seems approximately proportional to the power output, consistent with calcium stimulation of phosphorylase b kinase. In simulations, ADP concentration is highly sensitive to this proportionality, as (unlike in purely oxidative exercise) ADP concentration is not known to participate in any closed feedback loops in ischemic exercise.
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Affiliation(s)
- G J Kemp
- Department of Orthopaedic and Accident Surgery, University of Liverpool, United Kingdom
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