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Ruf K, Beer M, Köstler H, Weng AM, Neubauer H, Klein A, Platek K, Roth K, Beneke R, Hebestreit H. Size-adjusted muscle power and muscle metabolism in patients with cystic fibrosis are equal to healthy controls - a case control study. BMC Pulm Med 2019; 19:269. [PMID: 31888580 PMCID: PMC6937634 DOI: 10.1186/s12890-019-1039-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 12/19/2019] [Indexed: 12/20/2022] Open
Abstract
Background Skeletal muscle function dysfunction has been reported in patients with cystic fibrosis (CF). Studies so far showed inconclusive data whether reduced exercise capacity is related to intrinsic muscle dysfunction in CF. Methods Twenty patients with CF and 23 age-matched controls completed an incremental cardiopulmonary cycling test. Further, a Wingate anaerobic test to assess muscle power was performed. In addition, all participants completed an incremental knee-extension test with 31P magnetic resonance spectroscopy to assess muscle metabolism (inorganic phosphate (Pi) and phosphocreatinine (PCr) as well as intracellular pH). In the MRI, muscle cross-sectional area of the M. quadriceps (qCSA) was also measured. A subgroup of 15 participants (5 CF, 10 control) additionally completed a continuous high-intensity, high-frequency knee-extension exercise task during 31P magnetic resonance spectroscopy to assess muscle metabolism. Results Patients with CF showed a reduced exercise capacity in the incremental cardiopulmonary cycling test (VO2peak: CF 77.8 ± 16.2%predicted (36.5 ± 7.4 ml/qCSA/min), control 100.6 ± 18.8%predicted (49.1 ± 11.4 ml/qCSA/min); p < 0.001), and deficits in anaerobic capacity reflected by the Wingate test (peak power: CF 537 ± 180 W, control 727 ± 186 W; mean power: CF 378 ± 127 W, control 486 ± 126 W; power drop CF 12 ± 5 W, control 8 ± 4 W. all: p < 0.001). In the knee-extension task, patients with CF achieved a significantly lower workload (p < 0.05). However, in a linear model analysing maximal work load of the incremental knee-extension task and results of the Wingate test, respectively, only muscle size and height, but not disease status (CF or not) contributed to explaining variance. In line with this finding, no differences were found in muscle metabolism reflected by intracellular pH and the ratio of Pi/PCr at submaximal stages and peak exercise measured through MRI spectroscopy. Conclusions The lower absolute muscle power in patients with CF compared to controls is exclusively explained by the reduced muscle size in this study. No evidence was found for an intrinsic skeletal muscle dysfunction due to primary alterations of muscle metabolism.
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Affiliation(s)
- Katharina Ruf
- University Children's Hospital Würzburg, University of Würzburg, Josef-Schneider-Strasse 2, 97080, Würzburg, Germany.
| | - Meinrad Beer
- Department of Diagnostic and Interventional Radiology, University Hospital Ulm, Ulm, Germany.,Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, University of Würzburg, Würzburg, Germany
| | - Herbert Köstler
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, University of Würzburg, Würzburg, Germany
| | - Andreas Max Weng
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, University of Würzburg, Würzburg, Germany
| | - Henning Neubauer
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, University of Würzburg, Würzburg, Germany.,SRH Poliklinik Radiologie Suhl, Suhl, Germany
| | - Alexander Klein
- University Children's Hospital Würzburg, University of Würzburg, Josef-Schneider-Strasse 2, 97080, Würzburg, Germany
| | - Kathleen Platek
- University Children's Hospital Würzburg, University of Würzburg, Josef-Schneider-Strasse 2, 97080, Würzburg, Germany
| | - Kristina Roth
- University Children's Hospital Würzburg, University of Würzburg, Josef-Schneider-Strasse 2, 97080, Würzburg, Germany
| | - Ralph Beneke
- Institut für Sportwissenschaft und Motologie, Philipps Universität Marburg, Marburg, Germany
| | - Helge Hebestreit
- University Children's Hospital Würzburg, University of Würzburg, Josef-Schneider-Strasse 2, 97080, Würzburg, Germany
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Nachbauer W, Boesch S, Schneider R, Eigentler A, Wanschitz J, Poewe W, Schocke M. Bioenergetics of the calf muscle in Friedreich ataxia patients measured by 31P-MRS before and after treatment with recombinant human erythropoietin. PLoS One 2013; 8:e69229. [PMID: 23922695 PMCID: PMC3726701 DOI: 10.1371/journal.pone.0069229] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Accepted: 06/06/2013] [Indexed: 12/15/2022] Open
Abstract
Friedreich ataxia (FRDA) is caused by a GAA repeat expansion in the FXN gene leading to reduced expression of the mitochondrial protein frataxin. Recombinant human erythropoietin (rhuEPO) is suggested to increase frataxin levels, alter mitochondrial function and improve clinical scores in FRDA patients. Aim of the present pilot study was to investigate mitochondrial metabolism of skeletal muscle tissue in FRDA patients and examine effects of rhuEPO administration by phosphorus 31 magnetic resonance spectroscopy (31P MRS). Seven genetically confirmed FRDA patients underwent 31P MRS of the calf muscles using a rest-exercise-recovery protocol before and after receiving 3000 IU of rhuEPO for eight weeks. FRDA patients showed more rapid phosphocreatine (PCr) depletion and increased accumulation of inorganic phosphate (Pi) during incremental exercise as compared to controls. After maximal exhaustive exercise prolonged regeneration of PCR and slowed decline in Pi can be seen in FRDA. PCr regeneration as hallmark of mitochondrial ATP production revealed correlation to activity of complex II/III of the respiratory chain and to demographic values. PCr and Pi kinetics were not influenced by rhuEPO administration. Our results confirm mitochondrial dysfunction and exercise intolerance due to impaired oxidative phosphorylation in skeletal muscle tissue of FRDA patients. MRS did not show improved mitochondrial bioenergetics after eight weeks of rhuEPO exposition in skeletal muscle tissue of FRDA patients. Trial Registration EU Clinical Trials Register2008-000040-13
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Affiliation(s)
- Wolfgang Nachbauer
- Department of Neurology, Medical University Innsbruck, Innsbruck, Austria
| | - Sylvia Boesch
- Department of Neurology, Medical University Innsbruck, Innsbruck, Austria
- * E-mail:
| | - Rainer Schneider
- Department of Biochemistry, Leopold-Franzens-University Innsbruck, Innsbruck, Austria
| | - Andreas Eigentler
- Department of Neurology, Medical University Innsbruck, Innsbruck, Austria
| | - Julia Wanschitz
- Department of Neurology, Medical University Innsbruck, Innsbruck, Austria
| | - Werner Poewe
- Department of Neurology, Medical University Innsbruck, Innsbruck, Austria
| | - Michael Schocke
- Department of Radiology, Medical University Innsbruck, Innsbruck, Austria
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Libri V, Brown AP, Gambarota G, Haddad J, Shields GS, Dawes H, Pinato DJ, Hoffman E, Elliot PJ, Vlasuk GP, Jacobson E, Wilkins MR, Matthews PM. A pilot randomized, placebo controlled, double blind phase I trial of the novel SIRT1 activator SRT2104 in elderly volunteers. PLoS One 2012; 7:e51395. [PMID: 23284689 PMCID: PMC3527451 DOI: 10.1371/journal.pone.0051395] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2012] [Accepted: 10/31/2012] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND SRT2104 has been developed as a selective small molecule activator of SIRT1, a NAD(+)-dependent deacetylase involved in the regulation of energy homeostasis and the modulation of various metabolic pathways, including glucose metabolism, oxidative stress and lipid metabolism. SIRT1 has been suggested as putative therapeutic target in multiple age-related diseases including type 2 diabetes and dyslipidemias. We report the first clinical trial of SRT2104 in elderly volunteers. METHODS Oral doses of 0.5 or 2.0 g SRT2104 or matching placebo were administered once daily for 28 days. Pharmacokinetic samples were collected through 24 hours post-dose on days 1 and 28. Multiple pharmacodynamic endpoints were explored with oral glucose tolerance tests (OGTT), serum lipid profiles, magnetic resonance imaging (MRI) for assessment of whole body visceral and subcutaneous fat, maximal aerobic capacity test and muscle 31P magnetic resonance spectroscopy (MRS) for estimation of mitochondrial oxidative capacity. RESULTS SRT2104 was generally safe and well tolerated. Pharmacokinetic exposure increased less than dose-proportionally. Mean Tmax was 2-4 hours with elimination half-life of 15-20 hours. Serum cholesterol, LDL levels and triglycerides decreased with treatment. No significant changes in OGTT responses were observed. 31P MRS showed trends for more rapid calculated adenosine diphosphate (ADP) and phosphocreatine (PCr) recoveries after exercise, consistent with increased mitochondrial oxidative phosphorylation. CONCLUSIONS SRT2104 can be safely administered in elderly individuals and has biological effects in humans that are consistent with SIRT1 activation. The results of this study support further development of SRT2104 and may be useful in dose selection for future clinical trials in patients. TRIAL REGISTRATION ClinicalTrials.gov NCT00964340.
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Affiliation(s)
- Vincenzo Libri
- The National Institute for Health Research-Wellcome Trust Imperial College Clinical Research Facility, Imperial Centre for Translational and Experimental Medicine, Imperial College London, United Kingdom.
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Hug F, Grélot L, Le Fur Y, Cozzone PJ, Bendahan D. Recovery kinetics throughout successive bouts of various exercises in elite cyclists. Med Sci Sports Exerc 2007; 38:2151-8. [PMID: 17146323 DOI: 10.1249/01.mss.0000235882.86734.9a] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE In the present study we investigated whether a high volume of cycling training would influence the metabolic changes associated with a succession of three exhaustive cycling exercises. METHODS Seven professional road cyclists (VO2max: 74.3 +/- 3.7 mL.min.kg; maximal power tolerated: 475 +/- 18 W; training: 22 +/- 3 h.wk) and seven sport sciences students (VO2max: 54.2 +/- 5.3 mL.min.kg; maximal power tolerated: 341 +/- 26 W; training: 6 +/- 2 h.wk) performed three different exhaustive cycling exercise bouts (progressive, constant load, and sprint) on an electrically braked cycloergometer positioned near the magnetic resonance scanner. Less than 45 s after the completion of each exercise bout, recovery kinetics of high-energy phosphorylated compounds and pH were measured using P-MR spectroscopy. RESULTS Resting values for phosphomonoesters (PME) and phosphodiesters (PDE) were significantly elevated in the cyclist group (PME/ATP: 0.82 +/- 0.11 vs 0.58 +/- 0.19; PDE/ATP: 0.27 +/- 0.03 vs 0.21 +/- 0.05). Phosphocreatine (PCr) consumption and inorganic phosphate (Pi) accumulation measured at end of exercise bouts 1 (PCr: 6.5 +/- 3.2 vs 10.4 +/- 1.6 mM; Pi: 1.6 +/- 0.7 vs 6.8 +/- 3.4 mM) and 3 (PCr: 5.6 +/- 2.4 vs 9.3 +/- 3.9 mM; Pi: 1.5 +/- 0.5 vs 7.7 +/- 3.3 mM) were reduced in cyclists compared with controls. During the recovery period after each exercise bout, the pH-recovery rate was larger in professional road cyclists, whereas the PCr-recovery kinetics were significantly faster for cyclists only for bout 3. DISCUSSION Whereas the PDE and PME elevation at rest in professional cyclists may indicate fiber-type changes and an imbalance between glycogenolytic and glycolytic activity, the lower PCr consumption during exercise and the faster pH-recovery kinetic clearly suggest an improved mitochondrial function.
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Affiliation(s)
- François Hug
- University of Nantes, Nantes Atlantic Universities, Laboratory of Motricity, Interactions, and Performance, Nantes, France.
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5
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Greiner A, Esterhammer R, Bammer D, Messner H, Kremser C, Jaschke WR, Fraedrich G, Schocke MFH. High-energy phosphate metabolism in the calf muscle of healthy humans during incremental calf exercise with and without moderate cuff stenosis. Eur J Appl Physiol 2007; 99:519-31. [PMID: 17206438 DOI: 10.1007/s00421-006-0379-2] [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] [Accepted: 12/05/2006] [Indexed: 10/23/2022]
Abstract
It is known that the relevance of a peripheral stenosis for muscle function increases with exercise. Our intention was to investigate the impact of a moderate cuff stenosis (CS) at 120 mmHg of the superficial femoral artery on high-energy phosphate (HEP) metabolism during isotonic, incremental calf exercise. Serial phosphorus 31 magnetic resonance spectroscopy (31P MRS) and velocity-encoded phase-contrast MR imaging (VEPC MRI) were carried out in each leg of ten healthy male volunteers. Each leg underwent four increments of calf exercise (2, 3, 4 and 5 W) followed by recovery during separate exercise sessions with and without a CS at 120 mmHg. The serial 31P MRS measurements had a time resolution of 10 s. VEPC MRI was performed at the end of each increment during separate sessions. During all increments, we detected significant differences (P < 0.05) in the phosphocreatine (PCr) time constants and the amount of PCr hydrolysis between the sessions without and with CS. Regarding the time courses of the PCr, inorganic phosphate (Pi) and pH level, we observed significant differences (P < 0.002) during exercise and recovery. During both conditions, the end-increment PCr levels as well as blood flow correlated significantly with the mechanical power. The PCr time constants during exercise significantly correlated with the intramuscular pH, but not with blood flow or mechanical power. However, the PCr recovery time constants correlated significantly with blood flow and end-exercise pH. Our study shows that reduction of blood flow due to a peripheral stenosis results in a prolongation of PCr time constants, decreased PCr and pH level as well as increased Pi level during exercise. We believe that 31P MRS during incremental exercise might provide additional information for assessing the relevance of a peripheral stenosis and its impact on muscle function.
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Affiliation(s)
- Andreas Greiner
- Department of Surgery, Division of Vascular Surgery, Innsbruck Medical University, Anichstrasse 35, 6020, Innsbruck, Austria
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Cettolo V, Cautero M, Tam E, Francescato MP. Mitochondrial coupling in humans: assessment of the P/O2 ratio at the onset of calf exercise. Eur J Appl Physiol 2007; 99:593-604. [PMID: 17206437 DOI: 10.1007/s00421-006-0382-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/06/2006] [Indexed: 10/23/2022]
Abstract
Coupling of oxidation to ATP synthesis (P/O2 ratio) is a critical step in the conversion of carbon substrates to fuel (ATP) for cellular activity. The ability to quantitatively assess mitochondrial coupling in vivo can be a valuable tool for basic research and clinical purposes. At the onset of a square wave moderate exercise, the ratio between absolute amount of phosphocreatine split and O2 deficit (corrected for the amount of O2 released from the body O2 stores and in the absence of lactate production), is the mirror image of the P/O2 ratio. To calculate this value, cardiac output (Q), whole body O2 uptake (VO2), O2 deficit (O2(def)) and high-energy phosphates concentration (by 31P-NMR spectroscopy) in the calf muscles were measured on nine healthy volunteers at rest and during moderate intensity plantar flexion exercise (3.44 +/- 0.73 W per unit active muscle mass). Q and VO2 increased (from 4.68 +/- 1.56 to 5.83 +/- 1.59 l min(-1) and from 0.28 +/- 0.05 to 0.48 +/- 0.09 l min(-1), respectively), while phosphocreatine (PCr) concentration decreased significantly (22 +/- 6%) from rest to steady-state exercise. For each volunteer, "gross" O2(def) was corrected for the individual changes in the venous blood O2 stores (representing 49.9 +/- 9.5% of the gross O2(def)) yielding the "net" O2(def). Resting PCr concentration was estimated from the appropriate spectroscopy data. The so calculated P/O2 ratio amounted on average to 4.24 +/- 0.13 and was, in all nine subjects, very close to the literature values obtained directly on intact skeletal muscle. This unfolds the prospect of a non-invasive tool to quantitatively study mitochondrial coupling in vivo.
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Affiliation(s)
- V Cettolo
- Dipartimento di Scienze e Tecnologie Biomediche, M.A.T.I. Centre of Excellence, Università degli Studi di Udine, P.le Kolbe 4, 33100 Udine, Italy
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Falkensammer J, Stojakovic T, Huber K, Hammerer-Lercher A, Gruber I, Scharnagl H, Fraedrich G, Santner W, Schocke M, Greiner A. Serum levels of ischemia-modified albumin in healthy volunteers after exercise-induced calf-muscle ischemia. Clin Chem Lab Med 2007; 45:535-40. [PMID: 17439334 DOI: 10.1515/cclm.2007.087] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AbstractClin Chem Lab Med 2007;45:535–40.
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Affiliation(s)
- Juergen Falkensammer
- Division of Vascular Surgery, Medical University Innsbruck, Innsbruck, and 3rd Medical Department, Cardiology and Emergency Medicine, Wilhelminenhospital Vienna, Austria.
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8
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Schocke MFH, Esterhammer R, Ostermann S, Santner W, Gorny O, Fraedrich G, Jaschke WR, Greiner A. High-Energy Phosphate Metabolism During Calf Ergometry in Patients With Isolated Aorto-Iliac Artery Stenoses. Invest Radiol 2006; 41:874-82. [PMID: 17099426 DOI: 10.1097/01.rli.0000246148.09129.42] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES Patients with peripheral arterial disease (PAD) and aorto-iliac atherosclerotic lesions suffer from a broad range of complaints, such as pain at the hip, the thigh, and calf claudication. The purpose of this study was to investigate the high-energy metabolism in the calf muscle of patients with PAD with isolated aorto-iliac stenoses during incremental plantar flexion exercise. MATERIALS AND METHODS Using a 1.5 T whole-body magnetic resonance (MR) scanner, 12 patients with PAD with uni- or bilateral aorto-iliac atherosclerotic lesions and 10 healthy male controls underwent serial phosphor-31 MR spectroscopy during incremental exercise at 2, 3, 4, and 5 W. The phosphocreatine (PCr) time constants were calculated for each increment and recovery using a monoexponential model. In the patient group, the run-off resistance was determined on MR angiograms. In both the patients and the controls, the ankle brachial pressure index was measured. RESULTS The diseased legs exhibited significantly increased PCr time constants during the second and the third workload increment at 3 and 4 W, but not during the first increment at 2 W and recovery compared with normal controls. Only 3 diseased legs succeeded the last increment at 5 W. We detected significant correlations between the ankle brachial pressure index scores and the PCr time constants when including both the diseased and the control legs. The diseased legs showed a significant correlation with the run-off resistance only during the first increment. CONCLUSIONS Our study shows that the impairment of muscle metabolism, expressed by prolonged PCr time constants, occurs with greater work intensities in patients with aorto-iliac disease compared with patients with multisegmental PAD, as recently published, whereas our patients collective exhibited normal PCr recovery time constants. Our findings may help to understand variability of clinical symptoms in aorto-iliac PAD.
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Affiliation(s)
- Michael F H Schocke
- Department of Radiology, Division of Vascular Surgery, Innsbruck Medical University, Innsbruck, Austria.
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Greiner A, Esterhammer R, Messner H, Biebl M, Mühlthaler H, Fraedrich G, Jaschke WR, Schocke MFH. High-energy phosphate metabolism during incremental calf exercise in patients with unilaterally symptomatic peripheral arterial disease measured by phosphor 31 magnetic resonance spectroscopy. J Vasc Surg 2006; 43:978-86. [PMID: 16678693 DOI: 10.1016/j.jvs.2006.01.020] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2005] [Accepted: 01/13/2006] [Indexed: 12/01/2022]
Abstract
BACKGROUND The treadmill exercise test is the most important examination of the functional ability of patients with intermittent claudication or leg pain during exercise, but it does not provide any metabolic information in the calf muscle. The purpose of this study was to investigate the high-energy metabolism in the calf muscle during incremental progressive plantar flexion exercise of a selected peripheral arterial disease (PAD) patient group. METHODS Using a 1.5-T whole-body magnetic resonance scanner, 17 male patients with PAD who had 1 symptomatic and 1 asymptomatic leg and 9 healthy male controls underwent serial phosphor 31 (31P) magnetic resonance spectroscopy during incremental exercise at 2, 3, 4, and 5 W. Furthermore, magnetic resonance angiography was performed, and the ankle-brachial pressure index was determined in the patient group. The runoff resistance (ROR) was separately assessed in each patient's leg. RESULTS The symptomatic legs exhibited significantly increased phosphocreatine (PCr) time constants during the first three workload increments (2-4 W) and the recovery phase compared with the asymptomatic legs and the normal controls. Only two symptomatic legs reached the last increment at 5 W. Compared with the normal controls, the asymptomatic legs showed significantly increased PCr time constants only at 5 W. In the patient group, we detected significant correlations between the PCr time constants and the ROR, as well as the ankle-brachial pressure index. Moreover, the symptomatic legs presented significantly lower PCr levels and pH values at the end of exercise compared with the asymptomatic and control legs. CONCLUSIONS Our study shows that muscle function in PAD patients can be objectively quantified with the help of 31P magnetic resonance spectroscopy and correlates significantly with hemodynamic parameters such as ROR and ankle-brachial pressure index. Consequently, 31P magnetic resonance spectroscopy seems to be a useful method to monitor the muscle function of PAD patients for evaluation of established therapies or new therapeutic strategies during research trials.
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Affiliation(s)
- Andreas Greiner
- Department of Surgery, Division of Vascular Surgery, Innsbruck Medical University, Innsbruck, Austria
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Magkos F, Sidossis LS. Methodological approaches to the study of metabolism across individual tissues in man. Curr Opin Clin Nutr Metab Care 2005; 8:501-10. [PMID: 16079620 DOI: 10.1097/01.mco.0000170756.71114.78] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
PURPOSE OF REVIEW This article is intended to briefly overview available methodological approaches for the study of regional metabolism in man in vivo, and to summarize recent advances in this field of research. RECENT FINDINGS Several methods have been developed and currently allow for the qualitative and quantitative assessment of energy interconversions and substrate fluxes across individual tissues of man, including the measurement of arteriovenous concentration differences, microdialysis, and nuclear magnetic resonance spectroscopy of carbon, hydrogen, and phosphorus isotopes. Each method alone has been used rather extensively to examine certain aspects of organ and tissue metabolism under a variety of experimental conditions, and has contributed novel information in this regard. The most exciting development appears to be the combined use of more than one investigational technique, across one or more tissues simultaneously. A handful of recent studies have employed complex experimental designs or hybrid methodologies, ultimately demonstrating the potential for a more detailed assessment of metabolism at the local level. SUMMARY Clearly, advances in the use, performance, and applications of available methods are expected to provide improved and more powerful tools for the metabolic investigation of organs and tissues in humans in vivo.
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Affiliation(s)
- Faidon Magkos
- Laboratory of Nutrition and Clinical Dietetics, Department of Nutrition and Dietetics, Harokopio University, Athens, Greece
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Greiner A, Esterhammer R, Pilav S, Arnold W, Santner W, Neuhauser B, Fraedrich G, Jaschke WR, Schocke MFH. High-energy phosphate metabolism in the calf muscle during moderate isotonic exercise under different degrees of cuff compression: A phosphorus 31 magnetic resonance spectroscopy study. J Vasc Surg 2005; 42:259-67. [PMID: 16102624 DOI: 10.1016/j.jvs.2005.04.042] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2004] [Accepted: 04/24/2005] [Indexed: 12/01/2022]
Abstract
BACKGROUND The purpose of this study was to investigate phosphocreatine (PCr) and inorganic phosphate levels as well as pH changes in exercising muscle at a workload of 4.5 W under progressive cuff stenoses, whereby the flow reduction due to cuff compression was quantified by flow-sensitive magnetic resonance imaging. METHODS By using a whole-body 1.5-T magnetic resonance scanner and an exercise bench, serial phosphorus 31 (31P) magnetic resonance spectroscopy with a time resolution of 30 seconds was performed in 10 healthy men. Percentage changes in PCr, inorganic phosphate (Pi), and pH were statistically evaluated in comparison with baseline. The exercise protocol was characterized by a constant workload level of 4.5 W. Ischemic conditions were achieved by a cuff that was placed at the upper leg. Consecutively, increments of 0, 60, 90, 120, and 150 mm Hg were applied. Each increment lasted for 3 minutes. The following rest period was 10 minutes. RESULTS Blood flow increased significantly immediately after the onset of muscle exercise. No significant changes in blood flow were detected as long as the air pressure of the pneumatic cuff was 60 to 90 mm Hg. Significant reductions in blood flow were observed immediately after inflation of the cuff to 120 and 150 mm Hg. PCr passed into a steady state during the first increment with 0 mm Hg and showed no substantial changes during the increment with 60, 90, and 120 mm Hg. PCr hydrolysis seemed progressive during the 150-mm Hg increment. Pi passed into a plateau level at the onset of exercise and increased significantly at the increment of 150 mm Hg. The pH turned into a steady state with no significant changes during the increments up to 120 mm Hg. At 150 mm Hg, pH decreased progressively. PCr levels at the end of the 150-mm Hg increment correlated significantly and moderately with the reduction in blood flow. CONCLUSIONS Our study shows that the ischemic condition during constant muscle exercise is clearly characterized by PCr and Pi kinetics, as well as by pH changes. The correlation between the degree of blood flow reduction and PCr levels in the exercising muscle groups, which are supplied by the stenosed arteries, is the first essential of using 31P magnetic resonance spectroscopy in the assessment of the effect of arterial stenoses on muscle function in claudicants.
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Affiliation(s)
- Andreas Greiner
- Department of Surgery, Division of Vascular Surgery, Innsbruck Medical University, Austria.
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Hug F, Bendahan D, Le Fur Y, Cozzone PJ, Grélot L. Metabolic Recovery in Professional Road Cyclists: A 31P-MRS Study. Med Sci Sports Exerc 2005; 37:846-52. [PMID: 15870640 DOI: 10.1249/01.mss.0000162616.20085.b4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE Aerobic training of professional road cyclists is linked to tremendous aerobic capacities that have never been clearly related to what occur in skeletal muscles submitted to a specific exercise. The aim of the present study was to examine specifically metabolic recovery after an incremental cycling exercise performed until exhaustion in professional road cyclists as compared with moderately trained subjects and so using 31P- MRS. METHODS Subjects performed a progressive cycling exercise on a cycloergometer until exhaustion, then they were positioned back in the magnet (delay lower than 45 s) for recovery scanning. 31P spectra of thigh muscles were time averaged in 2-s blocks at rest and for 15 min throughout the recovery period. RESULTS For a significantly more intense exercise (477 +/- 28 vs 334 +/- 24 W in controls; P < 0.001), professional road cyclists displayed similar end-of-exercise extrapolated pH values (6.43 +/- 0.16 vs. 6.34 +/- 0.05 in controls) and a significantly higher PCr concentration (20.1 +/- 0.8 vs. 13.3 +/- 0.5 mM in controls, P < 0.001). The pH recovery kinetics provided the evidence of metabolic adaptations related to a specific training in professional cyclists with a significantly faster rate (P < 0.01) of pH return toward basal values (32.8 +/- 18.9 vs 10.8 +/- 6.7 mM x min(-1)). On the contrary, no significant difference was measured for the PCr recovery kinetics. At rest, PDE concentration was significantly higher in professional cyclists (2.50 +/- 0.80 vs 1.76 +/- 0.42 mM), likely indicating a difference regarding fiber-type composition. DISCUSSION The present data demonstrated for the first time that the tremendous aerobic capacity in professional cyclists is linked to faster pH recovery kinetics after a specific cycling exercise.
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Affiliation(s)
- François Hug
- Department of Sport Physiology, Faculty of Sport Sciences, IFR Marey, University of the Mediteranean (Aix-Marseille II), Marseille, France.
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Abstract
PURPOSE OF REVIEW A variety of imaging modalities can be used in muscle diseases. These range from plain x-rays to conventional magnetic resonance imaging (MRI) and phosphate magnetic resonance spectroscopy (MRS). This review places these imaging methods into their relevant clinical contexts on the basis of the best available research evidence. RECENT FINDINGS Plain x-rays have limited roles in imaging patients with muscle disease. An exception is identifying calcinosis in patients with myositis; there is some evidence that effective early treatment may reduce its frequency and severity. Scintigraphy has been used in several centers but it appears to have limited value. Ultrasound, though successfully used in a number of units, is relatively little used, though the evidence suggests it would be sensible if this method were adopted more widely. MRI is currently the key imaging modality. It is useful in diagnosing pyomyositis, diabetic muscle infarction, and inflammatory myositis. Its main proven value is identifying the best sites for biopsy in early myositis, though it can help differentiate between different forms of muscle disease when there is diagnostic uncertainty. The area of most intense ongoing original research is MRS, which can show the bioenergetics of normal and abnormal muscles. Changes in the ratios of inorganic phosphate and phosphocreatine, particularly during exercise provide insights into the metabolic consequences of muscle diseases and may, in the future, suggest alternative therapeutic approaches. SUMMARY Magnetic resonance imaging is a useful adjunct when diagnosing muscle diseases. It is particularly useful to identify suitable sites for muscle biopsy. Ultrasound may be equally helpful, though there is less supporting evidence from existing research. MRS is the area in which most current novel research is focused.
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Affiliation(s)
- David L Scott
- Department of Rheumatology, GKT School of Medicine, Weston Education Centre, Kings College, 10 Cutcombe Road, London SE5 9RS, UK.
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Schocke MFH, Esterhammer R, Arnold W, Kammerlander C, Burtscher M, Fraedrich G, Jaschke WR, Greiner A. High-energy phosphate metabolism during two bouts of progressive calf exercise in humans measured by phosphorus-31 magnetic resonance spectroscopy. Eur J Appl Physiol 2004; 93:469-79. [PMID: 15517340 DOI: 10.1007/s00421-004-1233-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/01/2004] [Indexed: 10/26/2022]
Abstract
According to the literature the steady-state level of phosphocreatine (PCr) has a linear relationship to the workload during muscle exercise intensities below the lactate threshold, whereas this linearity is impaired during exercise intensities above the lactate threshold. The purpose of this study was to investigate the linearity between PCr kinetics and workload during two bouts of isotonic incremental calf exercise with transitions from moderate- to high-intensity as well as from high- to moderate-intensity work rates. Using a whole-body 1.5 T MR scanner and a self-built exercise bench, we performed serial phosphorus-31 magnetic resonance spectroscopy ((31)P-MRS) with a time resolution of 30 s in nine healthy male volunteers. Changes in PCr, inorganic phosphate (Pi) and pH were statistically evaluated in comparison to the baseline. The exercise protocol started with a 4.5 W interval of 6 min followed by two bouts of 1.5 W increments. The workload was increased in 2-min intervals up to 9 W during the first bout and up to 7.5 W during the second bout. The second bout was preceded by a 4.5 W interval of 2 min and followed by a 4.5 W interval of 4 min. PCr hydrolysis achieved a steady state during each increment and was highly linear to the work rate (r (2), -0.796; P <0.001). Pi accumulated during each bout, whereas the pH decreased continuously during the first bout and did not exhibit any substantial decrease during the second bout. The metabolite levels and pH were expressed as the median value and the range. Our study confirms that steady-state PCr levels also have a linear relationship to work intensities above the lactate threshold, while pH changes do not have any impact on PCr degradation. The lack of substantial changes in pH during the second exercise bout indicates that prior high-intensity exercise leads to an activation of oxidative phosphorylation.
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Affiliation(s)
- Michael F H Schocke
- Division of Diagnostic Radiology I, Department of Radiology, Innsbruck Medical University, Anichstrasse 35, 6020 Innsbruck, Austria.
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