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Seung H, Wrobel J, Wadle C, Buehler T, Chiang D, Rettkowski J, Cabezas-Wallscheid N, Hechler B, Wolf D, Duerschmied D, Idzko M, Bode C, Von Zur Muehlen C, Hilgendorf I, Heidt T. The role of P2Y12 in cardiovascular disease beyond atherothrombosis: P2Y12 signaling promotes emergency hematopoiesis after myocardial infarction. Eur Heart J 2022. [DOI: 10.1093/eurheartj/ehac544.3006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Background
Adenosine diphosphate (ADP) plays a pivotal role in platelet activation. The purinergic ADP-receptor P2Y12 has therefore been targeted in the treatment of cardiovascular disease (CVD) to prevent atherothrombosis (1). Beyond P2Y12 expression on platelets, purinergic receptors have also been described on hematopoietic stem and progenitor cells (LSK) (2). After myocardial infarction (MI), accelerated LSK proliferation launches emergency hematopoiesis as the driving force behind the inflammatory response to MI, increasing inflammatory cell production in the bone marrow (BM) and providing leukocyte resupply for local cell recruitment to the infarct (3). The inflammatory cascade after MI covers intricate multilayered interactions between the injured myocardium and the hematopoietic BM that still remain to be fully elucidated and may unearth novel therapeutic strategies. Whereas P2X receptors have recently been found to be involved in cell trafficking (4), the role of P2Y receptors in the hematopoietic BM have not yet been characterized.
Purpose
This study aims to characterize the influence of P2Y12 signaling on emergency hematopoiesis and cardiac remodeling after MI.
Methods
Permanent coronary ligation was performed for MI to assess BM activation, inflammatory cell composition, cardiac remodeling and function in murine global and platelet-specific P2Y12 knockout models and under pharmacological P2Y12 inhibition with prasugrel using flow cytometry, qPCR, immunohistochemistry and echocardiography. In vitro studies including colony forming unit (CFU) assays and flow cytometry allowed for investigation of ADP-dependent effects on LSK cells and intracellular pathway analysis.
Results
We identified ADP as a danger signal for the hematopoietic BM, fueling emergency hematopoiesis by promoting Akt phosphorylation and cell cycle progression. Detection of P2Y12 expression in LSK implicated a direct effect of ADP on LSK via P2Y12 signaling. P2Y12 deficiency and P2Y12 inhibition with prasugrel decelerated emergency hematopoiesis and consecutively reduced the excessive inflammatory response to MI, translating to lower numbers of hematopoietic progenitors and inflammatory cells in the blood and infarct. Ultimately, P2Y12 inhibition ameliorated chronic adverse cardiac remodeling and preserved cardiac function after MI.
Conclusion
ADP-dependent P2Y12-mediated activation of hematopoietic stem and progenitor cells in the BM promotes emergency hematopoiesis after MI and fuels post-ischemic inflammation, proposing a novel role of P2Y12 antagonists in CVD beyond atherothrombosis.
Funding Acknowledgement
Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Deutsche Forschungsgemeinschaft (DFG)
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Affiliation(s)
- H Seung
- University Heart Center Freiburg, Cardiology and Angiology I , Freiburg , Germany
| | - J Wrobel
- University Heart Center Freiburg, Cardiology and Angiology I , Freiburg , Germany
| | - C Wadle
- University Heart Center Freiburg, Cardiology and Angiology I , Freiburg , Germany
| | - T Buehler
- University Heart Center Freiburg, Cardiology and Angiology I , Freiburg , Germany
| | - D Chiang
- University Heart Center Freiburg, Cardiology and Angiology I , Freiburg , Germany
| | - J Rettkowski
- Max Planck Institute of Immunobiology and Epigenetics , Freiburg , Germany
| | | | - B Hechler
- University of Strasbourg, INSERM, Etablissement Francais du Sang (EFS)-Grand Est , Strasbourg , France
| | - D Wolf
- University Heart Center Freiburg, Cardiology and Angiology I , Freiburg , Germany
| | - D Duerschmied
- University Medical Centre of Mannheim, Department of Cardiology, Angiology, Haemostaseology and Medical Intensive Care , Mannheim , Germany
| | - M Idzko
- Medical University of Vienna, Division of Pulmonology, Department of Medicine II , Vienna , Austria
| | - C Bode
- University Heart Center Freiburg, Cardiology and Angiology I , Freiburg , Germany
| | - C Von Zur Muehlen
- University Heart Center Freiburg, Cardiology and Angiology I , Freiburg , Germany
| | - I Hilgendorf
- University Heart Center Freiburg, Cardiology and Angiology I , Freiburg , Germany
| | - T Heidt
- University Heart Center Freiburg, Cardiology and Angiology I , Freiburg , Germany
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Pouymayou B, Buehler T, Kreis R, Boesch C. Test-retest analysis of multiple 31 P magnetization exchange pathways using asymmetric adiabatic inversion. Magn Reson Med 2016; 78:33-39. [PMID: 27455454 DOI: 10.1002/mrm.26337] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 05/31/2016] [Accepted: 06/17/2016] [Indexed: 01/08/2023]
Abstract
PURPOSE A 31 P-MR inversion transfer (IT) method with a short adiabatic inversion pulse is proposed and its test-retest reliability was evaluated for two spectral fitting strategies. METHODS Assessment in a test-retest design (3 Tesla, vastus muscles, 12 healthy volunteers, 14 inversion times, 22 ms asymmetric adiabatic inversion pulse, adiabatic excitation); spectral fitting in Fitting Tool for Interrelated Arrays of Datasets (FitAID) and Java Magnetic Resonance User Interface (jMRUI); least squares solution of the Bloch-McConnell-Solomon matrix formalism including all 14 measured time-points with equal weighting. RESULTS The cohort averages of k[PCr→γ-ATP] (phosphocreatine, PCr; adenosine triphosphate, ATP) are 0.246 ± 0.050s-1 versus 0.254 ± 0.050s-1 , and k[Pi→γ-ATP] 0.086 ± 0.033s-1 versus 0.066 ± 0.034s-1 (average ± standard deviation, jMRUI versus FitAID). Coefficients of variation of the differences between test and retest are lowest (9.5%) for k[PCr→γ-ATP] fitted in FitAID, larger (15.2%) for the fit in jMRUI, and considerably larger for k[Pi→γ-ATP] fitted in FitAID (43.4%) or jMRUI (47.9%). The beginning of the IT effect can be observed with magnetizations above 92% for noninverted lines while inversion of the ATP resonances is better than -72%. CONCLUSION The performance of the asymmetric adiabatic pulse allows an accurate observation of IT effects even in the early phase; the least squares fit of the Bloch-McConnell-Solomon matrix formalism is robust; and the type of spectral fitting can influence the results significantly. Magn Reson Med 78:33-39, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Bertrand Pouymayou
- Department of Clinical Research and Department of Radiology, University of Bern, Switzerland.,Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Tania Buehler
- Department of Clinical Research and Department of Radiology, University of Bern, Switzerland
| | - Roland Kreis
- Department of Clinical Research and Department of Radiology, University of Bern, Switzerland
| | - Chris Boesch
- Department of Clinical Research and Department of Radiology, University of Bern, Switzerland
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Buehler T, Bally L, Dokumaci AS, Stettler C, Boesch C. Methodological and physiological test-retest reliability of (13) C-MRS glycogen measurements in liver and in skeletal muscle of patients with type 1 diabetes and matched healthy controls. NMR Biomed 2016; 29:796-805. [PMID: 27074205 DOI: 10.1002/nbm.3531] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Revised: 02/04/2016] [Accepted: 03/08/2016] [Indexed: 06/05/2023]
Abstract
Glycogen is a major substrate in energy metabolism and particularly important to prevent hypoglycemia in pathologies of glucose homeostasis such as type 1 diabetes mellitus (T1DM). (13) C-MRS is increasingly used to determine glycogen in skeletal muscle and liver non-invasively; however, the low signal-to-noise ratio leads to long acquisition times, particularly when glycogen levels are determined before and after interventions. In order to ease the requirements for the subjects and to avoid systematic effects of the lengthy examination, we evaluated if a standardized preparation period would allow us to shift the baseline (pre-intervention) experiments to a preceding day. Based on natural abundance (13) C-MRS on a clinical 3 T MR system the present study investigated the test-retest reliability of glycogen measurements in patients with T1DM and matched controls (n = 10 each group) in quadriceps muscle and liver. Prior to the MR examination, participants followed a standardized diet and avoided strenuous exercise for two days. The average coefficient of variation (CV) of myocellular glycogen levels was 9.7% in patients with T1DM compared with 6.6% in controls after a 2 week period, while hepatic glycogen variability was 13.3% in patients with T1DM and 14.6% in controls. For comparison, a single-session test-retest variability in four healthy volunteers resulted in 9.5% for skeletal muscle and 14.3% for liver. Glycogen levels in muscle and liver were not statistically different between test and retest, except for hepatic glycogen, which decreased in T1DM patients in the retest examination, but without an increase of the group distribution. Since the CVs of glycogen levels determined in a "single session" versus "within weeks" are comparable, we conclude that the major source of uncertainty is the methodological error and that physiological variations can be minimized by a pre-study standardization. For hepatic glycogen examinations, familiarization sessions (MR and potentially strenuous interventions) are recommended. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Tania Buehler
- Department of Clinical Research and Department of Radiology, University of Bern, Switzerland
| | - Lia Bally
- Division of Endocrinology, Diabetes and Clinical Nutrition, Inselspital Bern, Switzerland
| | - Ayse Sila Dokumaci
- Department of Clinical Research and Department of Radiology, University of Bern, Switzerland
| | - Christoph Stettler
- Division of Endocrinology, Diabetes and Clinical Nutrition, Inselspital Bern, Switzerland
| | - Chris Boesch
- Department of Clinical Research and Department of Radiology, University of Bern, Switzerland
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Bally L, Zueger T, Buehler T, Dokumaci AS, Speck C, Pasi N, Ciller C, Paganini D, Feller K, Loher H, Rosset R, Wilhelm M, Tappy L, Boesch C, Stettler C. Metabolic and hormonal response to intermittent high-intensity and continuous moderate intensity exercise in individuals with type 1 diabetes: a randomised crossover study. Diabetologia 2016; 59:776-84. [PMID: 26739816 DOI: 10.1007/s00125-015-3854-7] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 12/09/2015] [Indexed: 10/22/2022]
Abstract
AIMS/HYPOTHESIS To investigate exercise-related fuel metabolism in intermittent high-intensity (IHE) and continuous moderate intensity (CONT) exercise in individuals with type 1 diabetes mellitus. METHODS In a prospective randomised open-label cross-over trial twelve male individuals with well-controlled type 1 diabetes underwent a 90 min iso-energetic cycling session at 50% maximal oxygen consumption ([Formula: see text]), with (IHE) or without (CONT) interspersed 10 s sprints every 10 min without insulin adaptation. Euglycaemia was maintained using oral (13)C-labelled glucose. (13)C Magnetic resonance spectroscopy (MRS) served to quantify hepatocellular and intramyocellular glycogen. Measurements of glucose kinetics (stable isotopes), hormones and metabolites complemented the investigation. RESULTS Glucose and insulin levels were comparable between interventions. Exogenous glucose requirements during the last 30 min of exercise were significantly lower in IHE (p = 0.02). Hepatic glucose output did not differ significantly between interventions, but glucose disposal was significantly lower in IHE (p < 0.05). There was no significant difference in glycogen consumption. Growth hormone, catecholamine and lactate levels were significantly higher in IHE (p < 0.05). CONCLUSIONS/INTERPRETATION IHE in individuals with type 1 diabetes without insulin adaptation reduced exogenous glucose requirements compared with CONT. The difference was not related to increased hepatic glucose output, nor to enhanced muscle glycogen utilisation, but to decreased glucose uptake. The lower glucose disposal in IHE implies a shift towards consumption of alternative substrates. These findings indicate a high flexibility of exercise-related fuel metabolism in type 1 diabetes, and point towards a novel and potentially beneficial role of IHE in these individuals. TRIAL REGISTRATION ClinicalTrials.gov NCT02068638 FUNDING: Swiss National Science Foundation (grant number 320030_149321/) and R&A Scherbarth Foundation (Switzerland).
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Affiliation(s)
- Lia Bally
- Division of Endocrinology, Diabetes and Clinical Nutrition, Inselspital, Bern University Hospital, and University of Bern, CH-3010, Bern, Switzerland
| | - Thomas Zueger
- Division of Endocrinology, Diabetes and Clinical Nutrition, Inselspital, Bern University Hospital, and University of Bern, CH-3010, Bern, Switzerland
| | - Tania Buehler
- Department Clinical Research and Department of Radiology, University of Bern, Bern, Switzerland
| | - Ayse S Dokumaci
- Department Clinical Research and Department of Radiology, University of Bern, Bern, Switzerland
| | - Christian Speck
- Division of Endocrinology, Diabetes and Clinical Nutrition, Inselspital, Bern University Hospital, and University of Bern, CH-3010, Bern, Switzerland
| | - Nicola Pasi
- Division of Endocrinology, Diabetes and Clinical Nutrition, Inselspital, Bern University Hospital, and University of Bern, CH-3010, Bern, Switzerland
| | - Carlos Ciller
- Department of Radiology, University Hospital Centre and University of Lausanne, Lausanne, Switzerland
- Signal Processing Core, Centre for Biomedical Imaging (CIBM), Lausanne, Switzerland
| | - Daniela Paganini
- Division of Endocrinology, Diabetes and Clinical Nutrition, Inselspital, Bern University Hospital, and University of Bern, CH-3010, Bern, Switzerland
| | - Katrin Feller
- Division of Endocrinology, Diabetes and Clinical Nutrition, Inselspital, Bern University Hospital, and University of Bern, CH-3010, Bern, Switzerland
| | - Hannah Loher
- Division of Endocrinology, Diabetes and Clinical Nutrition, Inselspital, Bern University Hospital, and University of Bern, CH-3010, Bern, Switzerland
| | - Robin Rosset
- Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Matthias Wilhelm
- Preventive Cardiology and Sports Medicine, Inselspital, Bern University Hospital, and University of Bern, Bern, Switzerland
| | - Luc Tappy
- Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Chris Boesch
- Department Clinical Research and Department of Radiology, University of Bern, Bern, Switzerland
| | - Christoph Stettler
- Division of Endocrinology, Diabetes and Clinical Nutrition, Inselspital, Bern University Hospital, and University of Bern, CH-3010, Bern, Switzerland.
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Christ ER, Egger A, Allemann S, Buehler T, Kreis R, Boesch C. Effects of aerobic exercise on ectopic lipids in patients with growth hormone deficiency before and after growth hormone replacement therapy. Sci Rep 2016; 6:19310. [PMID: 26792091 PMCID: PMC4726290 DOI: 10.1038/srep19310] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 12/09/2015] [Indexed: 01/21/2023] Open
Abstract
Growth hormone replacement therapy (GHRT) increases exercise capacity and insulin resistance while it decreases fat mass in growth hormone-deficient patients (GHD). Ectopic lipids (intramyocellular (IMCL) and intrahepatocellular lipids (IHCL) are related to insulin resistance. The effect of GHRT on ectopic lipids is unknown. It is hypothesized that exercise-induced utilization of ectopic lipids is significantly decreased in GHD patients and normalized by GHRT. GHD (4 females, 6 males) and age/gender/waist-matched control subjects (CS) were studied. VO2max was assessed on a treadmill and insulin sensitivity determined by a two-step hyperinsulinaemic-euglycaemic clamp. Visceral (VAT) and subcutaneous (SAT) fat were quantified by MR-imaging. IHCL and IMCL were measured before and after a 2 h exercise at 50-60% of VO2max using MR-spectroscopy (∆IMCL, ∆IHCL). Identical investigations were performed after 6 months of GHRT. VO2max was similar in GHD and CS and significantly increased after GHRT; GHRT significantly decreased SAT and VAT. 2 h-exercise resulted in a decrease in IMCL (significant in CS and GHRT) and a significant increase in IHCL in CS and GHD pre and post GHRT. GHRT didn't significantly impact on ∆IMCL and ∆IHCL. We conclude that aerobic exercise affects ectopic lipids in patients and controls. GHRT increases exercise capacity without influencing ectopic lipids.
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Affiliation(s)
- Emanuel R Christ
- Division of Endocrinology, Diabetology and Clinical Nutrition, University Hospital of Bern, Inselspital, CH-3010 Bern, Switzerland
| | - Andrea Egger
- Division of Endocrinology, Diabetology and Clinical Nutrition, University Hospital of Bern, Inselspital, CH-3010 Bern, Switzerland.,Department of Internal Medicine, University Hospital of Basel, CH-4056 Basel, Switzerland
| | - Sabin Allemann
- Division of Endocrinology, Diabetology and Clinical Nutrition, University Hospital of Bern, Inselspital, CH-3010 Bern, Switzerland
| | - Tania Buehler
- Department of Clinical Research, Division of MR-Spectroscopy and Methodology, University of Bern, Inselspital, CH-3010 Bern, Switzerland
| | - Roland Kreis
- Department of Clinical Research, Division of MR-Spectroscopy and Methodology, University of Bern, Inselspital, CH-3010 Bern, Switzerland
| | - Chris Boesch
- Department of Clinical Research, Division of MR-Spectroscopy and Methodology, University of Bern, Inselspital, CH-3010 Bern, Switzerland
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Bally L, Buehler T, Dokumaci AS, Boesch C, Stettler C. Hepatic and intramyocellular glycogen stores in adults with type 1 diabetes and healthy controls. Diabetes Res Clin Pract 2015; 109:e1-3. [PMID: 26013568 DOI: 10.1016/j.diabres.2015.05.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Revised: 04/13/2015] [Accepted: 05/01/2015] [Indexed: 10/23/2022]
Abstract
Glycogen levels in liver and skeletal muscle assessed non-invasively using magnetic resonance spectroscopy after a 48-h pre-study period including a standardized diet and withdrawal from exercise did not differ between individuals with well-controlled Type 1 DM and matched healthy controls.
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Affiliation(s)
- L Bally
- Division of Endocrinology, Diabetes and Clinical Nutrition, University Hospital and Inselspital, University of Bern, Switzerland
| | - T Buehler
- Division of Endocrinology, Diabetes and Clinical Nutrition, University Hospital and Inselspital, University of Bern, Switzerland
| | - A S Dokumaci
- Division of Endocrinology, Diabetes and Clinical Nutrition, University Hospital and Inselspital, University of Bern, Switzerland
| | - C Boesch
- Division of Endocrinology, Diabetes and Clinical Nutrition, University Hospital and Inselspital, University of Bern, Switzerland
| | - C Stettler
- Division of Endocrinology, Diabetes and Clinical Nutrition, University Hospital and Inselspital, University of Bern, Switzerland.
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Buehler T, Kreis R, Boesch C. Comparison of (31)P saturation and inversion magnetization transfer in human liver and skeletal muscle using a clinical MR system and surface coils. NMR Biomed 2015; 28:188-199. [PMID: 25483778 DOI: 10.1002/nbm.3242] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Revised: 11/07/2014] [Accepted: 11/10/2014] [Indexed: 06/04/2023]
Abstract
(31)P MRS magnetization transfer ((31)P-MT) experiments allow the estimation of exchange rates of biochemical reactions, such as the creatine kinase equilibrium and adenosine triphosphate (ATP) synthesis. Although various (31)P-MT methods have been successfully used on isolated organs or animals, their application on humans in clinical scanners poses specific challenges. This study compared two major (31)P-MT methods on a clinical MR system using heteronuclear surface coils. Although saturation transfer (ST) is the most commonly used (31)P-MT method, sequences such as inversion transfer (IT) with short pulses might be better suited for the specific hardware and software limitations of a clinical scanner. In addition, small NMR-undetectable metabolite pools can transfer MT to NMR-visible pools during long saturation pulses, which is prevented with short pulses. (31)P-MT sequences were adapted for limited pulse length, for heteronuclear transmit-receive surface coils with inhomogeneous B1 , for the need for volume selection and for the inherently low signal-to-noise ratio (SNR) on a clinical 3-T MR system. The ST and IT sequences were applied to skeletal muscle and liver in 10 healthy volunteers. Monte-Carlo simulations were used to evaluate the behavior of the IT measurements with increasing imperfections. In skeletal muscle of the thigh, ATP synthesis resulted in forward reaction constants (k) of 0.074 ± 0.022 s(-1) (ST) and 0.137 ± 0.042 s(-1) (IT), whereas the creatine kinase reaction yielded 0.459 ± 0.089 s(-1) (IT). In the liver, ATP synthesis resulted in k = 0.267 ± 0.106 s(-1) (ST), whereas the IT experiment yielded no consistent results. ST results were close to literature values; however, the IT results were either much larger than the corresponding ST values and/or were widely scattered. To summarize, ST and IT experiments can both be implemented on a clinical body scanner with heteronuclear transmit-receive surface coils; however, ST results are much more robust against experimental imperfections than the current implementation of IT.
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Affiliation(s)
- Tania Buehler
- Departments of Clinical Research and Radiology, University of Bern, Switzerland
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Decorte N, Buehler T, Caldas de Almeida Araujo E, Vignaud A, Carlier PG. Noninvasive estimation of oxygen consumption in human calf muscle through combined NMR measurements of ASL perfusion and T₂ oxymetry. J Vasc Res 2014; 51:360-8. [PMID: 25531648 DOI: 10.1159/000368194] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 09/03/2014] [Indexed: 11/19/2022] Open
Abstract
The objective of this work was to demonstrate the feasibility of measuring muscle O2 consumption (V˙O2) noninvasively with a combination of functional nuclear magnetic resonance (NMR) imaging methods, and to verify that changes in muscle V˙O2 can be detected with a temporal resolution compatible with physiological investigation and patient ease. T2-based oxymetry of arterial and venous blood was combined with the arterial-spin labeling (ASL)-based determination of muscle perfusion. These measurements were performed on 8 healthy volunteers under normoxic and hypoxic conditions in order to assess the sensitivity of measurements over a range of saturation values. Blood samples were drawn simultaneously and used to titrate blood T2 measurements versus hemoglobin O2 saturation (%HbO2) in vitro. The in vitro calibration curve of blood T2 fitted very well with the %HbO2 (r(2): 0.95). The in vivo venous T2 measurements agreed well with the in vitro measurements (intraclass correlation coefficient 0.82, 95% confidence interval 0.61-0.91). Oxygen extraction at rest decreased in the calf muscles subjected to hypoxia (p = 0.031). The combination of unaltered muscle perfusion and pinched arteriovenous O2 difference (p = 0.038) pointed towards a reduced calf muscle V˙O2 during transient hypoxia (p = 0.018). The results of this pilot study confirmed that muscle O2 extraction and V˙O2 can be estimated noninvasively using a combination of functional NMR techniques. Further studies are needed to confirm the usefulness in a larger sample of volunteers and patients.
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Egger A, Kreis R, Allemann S, Stettler C, Diem P, Buehler T, Boesch C, Christ ER. The effect of aerobic exercise on intrahepatocellular and intramyocellular lipids in healthy subjects. PLoS One 2013; 8:e70865. [PMID: 23967125 PMCID: PMC3743875 DOI: 10.1371/journal.pone.0070865] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Accepted: 06/21/2013] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Intrahepatocellular (IHCL) and intramyocellular (IMCL) lipids are ectopic lipid stores. Aerobic exercise results in IMCL utilization in subjects over a broad range of exercise capacity. IMCL and IHCL have been related to impaired insulin action at the skeletal muscle and hepatic level, respectively. The acute effect of aerobic exercise on IHCL is unknown. Possible regulatory factors include exercise capacity, insulin sensitivity and fat availability subcutaneous and visceral fat mass). AIM To concomitantly investigate the effect of aerobic exercise on IHCL and IMCL in healthy subjects, using Magnetic Resonance spectroscopy. METHODS Normal weight, healthy subjects were included. Visit 1 consisted of a determination of VO2max on a treadmill. Visit 2 comprised the assessment of hepatic and peripheral insulin sensitivity by a two-step hyperinsulinaemic euglycaemic clamp. At Visit 3, subcutaneous and visceral fat mass were assessed by whole body MRI, IHCL and IMCL before and after a 2-hours aerobic exercise (50% of VO(2max)) using ¹H-MR-spectroscopy. RESULTS Eighteen volunteers (12M, 6F) were enrolled in the study (age, 37.6±3.2 years, mean±SEM; VO(2max), 53.4±2.9 mL/kg/min). Two hours aerobic exercise resulted in a significant decrease in IMCL (-22.6±3.3, % from baseline) and increase in IHCL (+34.9±7.6, % from baseline). There was no significant correlation between the exercise-induced changes in IMCL and IHCL and exercise capacity, subcutaneous and visceral fat mass and hepatic or peripheral insulin sensitivity. CONCLUSIONS IMCL and IHCL are flexible ectopic lipid stores that are acutely influenced by physical exercise, albeit in different directions. TRIAL REGISTRATION ClinicalTrial.gov NCT00491582.
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Affiliation(s)
- Andrea Egger
- Division of Endocrinology, Diabetology and Clinical Nutrition, University Hospital of Bern, Inselspital, Bern, Switzerland
| | - Roland Kreis
- Department of Clinical Research, Magnetic Resonance Spectroscopy and Methodology, University of Bern, Bern, Switzerland
| | - Sabin Allemann
- Division of Endocrinology, Diabetology and Clinical Nutrition, University Hospital of Bern, Inselspital, Bern, Switzerland
| | - Christoph Stettler
- Division of Endocrinology, Diabetology and Clinical Nutrition, University Hospital of Bern, Inselspital, Bern, Switzerland
| | - Peter Diem
- Division of Endocrinology, Diabetology and Clinical Nutrition, University Hospital of Bern, Inselspital, Bern, Switzerland
| | - Tania Buehler
- Department of Clinical Research, Magnetic Resonance Spectroscopy and Methodology, University of Bern, Bern, Switzerland
| | - Chris Boesch
- Department of Clinical Research, Magnetic Resonance Spectroscopy and Methodology, University of Bern, Bern, Switzerland
| | - Emanuel R. Christ
- Division of Endocrinology, Diabetology and Clinical Nutrition, University Hospital of Bern, Inselspital, Bern, Switzerland
- * E-mail:
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Theytaz F, Noguchi Y, Egli L, Campos V, Buehler T, Hodson L, Patterson BW, Nishikata N, Kreis R, Mittendorfer B, Fielding B, Boesch C, Tappy L. Effects of supplementation with essential amino acids on intrahepatic lipid concentrations during fructose overfeeding in humans. Am J Clin Nutr 2012; 96:1008-16. [PMID: 23034968 DOI: 10.3945/ajcn.112.035139] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND A high dietary protein intake has been shown to blunt the deposition of intrahepatic lipids in high-fat- and high-carbohydrate-fed rodents and humans. OBJECTIVE The aim of this study was to evaluate the effect of essential amino acid supplementation on the increase in hepatic fat content induced by a high-fructose diet in healthy subjects. DESIGN Nine healthy male volunteers were studied on 3 occasions in a randomized, crossover design after 6 d of dietary intervention. Dietary conditions consisted of a weight-maintenance balanced diet (control) or the same balanced diet supplemented with 3 g fructose · kg(-1) · d(-1) and 6.77 g of a mixture of 5 essential amino acids 3 times/d (leucine, isoleucine, valine, lysine, and threonine) (HFrAA) or with 3 g fructose · kg(-1) · d(-1) and a maltodextrin placebo 3 times/d (HFr); there was a washout period of 4 to 10 wk between each condition. For each condition, the intrahepatocellular lipid (IHCL) concentration, VLDL-triglyceride concentration, and VLDL-[(13)C]palmitate production were measured after oral loading with [(13)C]fructose. RESULTS HFr increased the IHCL content (1.27 ± 0.31 compared with 2.74 ± 0.55 vol %; P < 0.05) and VLDL-triglyceride (0.55 ± 0.06 compared with 1.40 ± 0.15 mmol/L; P < 0.05). HFr also enhanced VLDL-[(13)C]palmitate production. HFrAA significantly decreased IHCL compared with HFr (to 2.30 ± 0.43 vol%; P < 0.05) but did not change VLDL-triglyceride concentrations or VLDL-[(13)C]palmitate production. CONCLUSIONS Supplementation with essential amino acids blunts the fructose-induced increase in IHCL but not hypertriglyceridemia. This is not because of inhibition of VLDL-[(13)C]palmitate production. This trial was registered at www.clinicaltrials.gov as NCT01119989.
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Affiliation(s)
- Fanny Theytaz
- Department of Physiology, University of Lausanne, Lausanne, Switzerland
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Buehler T, Ramseier N, Machann J, Schwenzer NF, Boesch C. Magnetic resonance imaging based determination of body compartments with the versatile, interactive sparse sampling (VISS) method. J Magn Reson Imaging 2012; 36:951-60. [DOI: 10.1002/jmri.23707] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Accepted: 04/18/2012] [Indexed: 01/27/2023] Open
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Décombaz J, Jentjens R, Ith M, Scheurer E, Buehler T, Jeukendrup A, Boesch C. Fructose and galactose enhance postexercise human liver glycogen synthesis. Med Sci Sports Exerc 2012; 43:1964-71. [PMID: 21407126 DOI: 10.1249/mss.0b013e318218ca5a] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE Both liver and muscle glycogen stores play a fundamental role in exercise and fatigue, but the effect of different CHO sources on liver glycogen synthesis in humans is unclear. The aim was to compare the effect of maltodextrin (MD) drinks containing galactose, fructose, or glucose on postexercise liver glycogen synthesis. METHODS In this double-blind, triple crossover, randomized clinical trial, 10 well-trained male cyclists performed three experimental exercise sessions separated by at least 1 wk. After performing a standard exercise protocol to exhaustion, subjects ingested one of three 15% CHO solutions, namely, FRU (MD + fructose, 2:1), GAL (MD + galactose, 2:1), or GLU (MD + glucose, 2:1), each providing 69 g CHO·h(-1) during 6.5 h of recovery. Liver glycogen changes were followed using (13)C magnetic resonance spectroscopy. RESULTS Liver glycogen concentration increased at faster rates with FRU (24 ± 2 mmol·L(-1)·h(-1), P < 0.001) and with GAL (28 ± 3 mmol·L(-1)·h(-1), P < 0.001) than with GLU (13 ± 2 mmol·L(-1)·h(-1)). Liver volumes increased (P < 0.001) with FRU (9% ± 2%) and with GAL (10% ± 2%) but not with GLU (2% ± 1%, NS). Net glycogen synthesis appeared linear and was faster with FRU (8.1 ± 0.6 g·h(-1), P < 0.001) and with GAL (8.6 ± 0.9 g·h(-1), P < 0.001) than with GLU (3.7 ± 0.5 g·h(-1)). CONCLUSIONS When ingested at a rate designed to saturate intestinal CHO transport systems, MD drinks with added fructose or galactose were twice as effective as MD + glucose in restoring liver glycogen during short-term postexercise recovery.
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Stellingwerff T, Anwander H, Egger A, Buehler T, Kreis R, Decombaz J, Boesch C. Effect of two β-alanine dosing protocols on muscle carnosine synthesis and washout. Amino Acids 2011; 42:2461-72. [DOI: 10.1007/s00726-011-1054-4] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Accepted: 07/30/2011] [Indexed: 01/01/2023]
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Egger A, Buehler T, Boesch C, Diem P, Stettler C, Christ ER. The effect of GH replacement therapy on different fat compartments: a whole-body magnetic resonance imaging study. Eur J Endocrinol 2011; 164:23-9. [PMID: 20930061 DOI: 10.1530/eje-10-0702] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Patients with GH deficiency (GHD) are insulin resistant with an increase in visceral fat mass (FM). Whether this holds true when sedentary control subjects (CS) are matched for waist has not been documented. GH replacement therapy (GHRT) results in a decrease in FM. Whether the decrease in FM is mainly related to a reduction in visceral FM remains to be proven. The aim was to separately assess visceral and subcutaneous FM in relation to insulin resistance (IR) in GHD patients before and after GHRT and in sedentary CS. METHODS Ten patients with GHD were investigated before and 6 months after GHRT. Sedentary CS matched for age, gender, body mass index, and waist were assessed. Exercise capacity was measured as VO(2max) using an incremental work load on a treadmill. Visceral and subcutaneous FM were measured using whole-body magnetic resonance imaging and IR by the homeostasis model assessment of IR (HOMA-IR) index. RESULTS GHD patients had a non-significantly lower VO(2max) but did not have increased subcutaneous and visceral FM compared with CS. GHRT resulted in a similar relative decrease in subcutaneous and visceral FM. Compared with CS, GHD patients showed a lower HOMA-IR. GHRT tended to increase HOMA-IR. CONCLUSION Matching for waist and separate assessment of visceral and subcutaneous FM may be critical in the evaluation of body composition and IR in GHD patients before and after GHRT.
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Affiliation(s)
- A Egger
- Division of Endocrinology, Diabetes, and Clinical Nutrition, Inselspital, Bern University Hospital Department of Clinical Research, University of Bern, CH-3010 Bern, Switzerland
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Stellingwerff T, Anwander H, Egger A, Buehler T, Kreis R, Boesch C, Decombaz J. The Effect Of Two b-alanine Dosing Protocols On Muscle Carnosine Synthesis And Washout. Med Sci Sports Exerc 2010. [DOI: 10.1249/01.mss.0000385978.12373.98] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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