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Rushin A, McLeod MA, Ragavan M, Merritt ME. Observing exocrine pancreas metabolism using a novel pancreas perfusion technique in combination with hyperpolarized [1- 13 C]pyruvate. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2023; 61:748-758. [PMID: 37482899 PMCID: PMC10800648 DOI: 10.1002/mrc.5382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 06/28/2023] [Accepted: 07/06/2023] [Indexed: 07/25/2023]
Abstract
In a clinical setting, ex vivo perfusions are routinely used to maintain and assess organ viability prior to transplants. Organ perfusions are also a model system to examine metabolic flux while retaining the local physiological structure, with significant success using hyperpolarized (HP) 13 C NMR in this context. We use a novel exocrine pancreas perfusion technique via the common bile duct to assess acinar cell metabolism with HP [1-13 C]pyruvate. The exocrine component of the pancreas produces digestive enzymes through the ductal system and is often neglected in research on the pancreas. Real-time production of [1-13 C]lactate, [1-13 C]alanine, [1-13 C]malate, [4-13 C]malate, [1-13 C]aspartate, and H13 CO3 - was detected. The appearance of these resonances indicates flux through both pyruvate dehydrogenase and pyruvate carboxylase. We studied excised pancreata from C57BL/6J mice and NOD.Rag1-/- .AI4α/β mice, a commonly used model of Type 1 Diabetes (T1D). Pancreata from the T1D mice displayed increased lactate to alanine ratio without changes in oxygen consumption, signifying increased cytosolic NADH levels. The mass isotopologue analysis of the extracted pancreas tissue using gas chromatography-mass spectrometry revealed confirmatory 13 C enrichment in multiple TCA cycle metabolites that are products of pyruvate carboxylation. The methodology presented here has the potential to provide insight into mechanisms underlying several pancreatic diseases, such as diabetes, pancreatitis, and pancreatic cancer.
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Affiliation(s)
- Anna Rushin
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Marc A. McLeod
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Mukundan Ragavan
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Matthew E. Merritt
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, Florida, USA
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2
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Johnston TL, Edison AS, Ramaswamy V, Freytag N, Merritt ME, Thomas JN, Hooker JW, Litvak IM, Brey WW. Application of Counter-wound Multi-arm Spirals in HTS Resonator Design. IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY : A PUBLICATION OF THE IEEE SUPERCONDUCTIVITY COMMITTEE 2022; 32:1500304. [PMID: 35449718 PMCID: PMC9017787 DOI: 10.1109/tasc.2022.3146109] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Significant sensitivity improvements have been achieved by utilizing high temperature superconducting (HTS) resonators in nuclear magnetic resonance (NMR) probes. Many nuclei such as 13C benefit from strong excitation fields which cannot be produced by traditional HTS resonator designs. We investigate the use of double-sided, counter-wound multi-arm spiral HTS resonators with the aim of increasing the excitation field at the required nuclear Larmor frequency for 13C. When compared to double-sided, counter-wound spiral resonators with similar geometry, simulations indicate that the multi-arm spiral version develops a more uniform current distribution. Preliminary tests of a two-arm resonator indicate that it may produce a stronger excitation field.
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Affiliation(s)
- Taylor L Johnston
- National High Magnetic Laboratory, Tallahassee, FL 32310, USA and also with the Department of Chemistry and Biochemistry, Florida State University
| | | | | | | | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32601, USA
| | - Jeremy N Thomas
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, USA and also with the Department of Physics, Florida State University
| | - Jerris W Hooker
- Department of Electrical and Computer Engineering, FAMU-FSU College of Engineering, Tallahassee, FL 32310, USA
| | - Ilya M Litvak
- National High Magnetic Laboratory, Tallahassee, FL 32310, USA and also with Florida State University
| | - William W Brey
- National High Magnetic Laboratory, Tallahassee, FL 32310, USA and also with Florida State University
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3
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Rahim M, Ragavan M, Deja S, Merritt ME, Burgess SC, Young JD. INCA 2.0: A tool for integrated, dynamic modeling of NMR- and MS-based isotopomer measurements and rigorous metabolic flux analysis. Metab Eng 2022; 69:275-285. [PMID: 34965470 PMCID: PMC8789327 DOI: 10.1016/j.ymben.2021.12.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 12/17/2021] [Accepted: 12/22/2021] [Indexed: 01/03/2023]
Abstract
Metabolic flux analysis (MFA) combines experimental measurements and computational modeling to determine biochemical reaction rates in live biological systems. Advancements in analytical instrumentation, such as nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS), have facilitated chemical separation and quantification of isotopically enriched metabolites. However, no software packages have been previously described that can integrate isotopomer measurements from both MS and NMR analytical platforms and have the flexibility to estimate metabolic fluxes from either isotopic steady-state or dynamic labeling experiments. By applying physiologically relevant cardiac and hepatic metabolic models to assess NMR isotopomer measurements, we herein test and validate new modeling capabilities of our enhanced flux analysis software tool, INCA 2.0. We demonstrate that INCA 2.0 can simulate and regress steady-state 13C NMR datasets from perfused hearts with an accuracy comparable to other established flux assessment tools. Furthermore, by simulating the infusion of three different 13C acetate tracers, we show that MFA based on dynamic 13C NMR measurements can more precisely resolve cardiac fluxes compared to isotopically steady-state flux analysis. Finally, we show that estimation of hepatic fluxes using combined 13C NMR and MS datasets improves the precision of estimated fluxes by up to 50%. Overall, our results illustrate how the recently added NMR data modeling capabilities of INCA 2.0 can enable entirely new experimental designs that lead to improved flux resolution and can be applied to a wide range of biological systems and measurement time courses.
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Affiliation(s)
- Mohsin Rahim
- Department of Chemical and Biomolecular, Nashville, TN, 37212, USA
| | - Mukundan Ragavan
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, FL, USA
| | - Stanislaw Deja
- Center for Human Nutrition, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, FL, USA
| | - Shawn C Burgess
- Center for Human Nutrition, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jamey D Young
- Department of Chemical and Biomolecular, Nashville, TN, 37212, USA; Department of Molecular Physiology and Biophysics, Vanderbilt University, School of Engineering, Nashville, TN, 37212, USA.
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Ragavan M, Li M, Giacalone AG, Wood CE, Keller-Wood M, Merritt ME. Application of Carbon-13 Isotopomer Analysis to Assess Perinatal Myocardial Glucose Metabolism in Sheep. Metabolites 2021; 11:33. [PMID: 33466367 PMCID: PMC7824843 DOI: 10.3390/metabo11010033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 12/16/2020] [Accepted: 01/01/2021] [Indexed: 11/16/2022] Open
Abstract
Ovine models of pregnancy have been used extensively to study maternal-fetal interactions and have provided considerable insight into nutrient transfer to the fetus. Ovine models have also been utilized to study congenital heart diseases. In this work, we demonstrate a comprehensive assessment of heart function and metabolism using a perinatal model of heart function with the addition of a [U-13C]glucose as tracer to study central energy metabolism. Using nuclear magnetic resonance spectroscopy, and metabolic modelling, we estimate myocardial citric acid cycle turnover (normalized for oxygen consumption), substrate selection, and anaplerotic fluxes. This methodology can be applied to studying acute and chronic effects of hormonal signaling in future studies.
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Affiliation(s)
- Mukundan Ragavan
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32603, USA; (M.R.); (A.G.G.)
| | - Mengchen Li
- Department of Pharmacodynamics, University of Florida, Gainesville, FL 32610, USA; (M.L.); (M.K.-W.)
| | - Anthony G. Giacalone
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32603, USA; (M.R.); (A.G.G.)
| | - Charles E. Wood
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, FL 32603, USA;
- Donald H Barron Reproductive and Perinatal Biology Research Program, University of Florida, Gainesville, FL 32603, USA
| | - Maureen Keller-Wood
- Department of Pharmacodynamics, University of Florida, Gainesville, FL 32610, USA; (M.L.); (M.K.-W.)
- Donald H Barron Reproductive and Perinatal Biology Research Program, University of Florida, Gainesville, FL 32603, USA
| | - Matthew E. Merritt
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32603, USA; (M.R.); (A.G.G.)
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Muyyarikkandy MS, McLeod M, Maguire M, Mahar R, Kattapuram N, Zhang C, Surugihalli C, Muralidaran V, Vavilikolanu K, Mathews CE, Merritt ME, Sunny NE. Branched chain amino acids and carbohydrate restriction exacerbate ketogenesis and hepatic mitochondrial oxidative dysfunction during NAFLD. FASEB J 2020; 34:14832-14849. [PMID: 32918763 DOI: 10.1096/fj.202001495r] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 08/10/2020] [Accepted: 08/24/2020] [Indexed: 12/16/2022]
Abstract
Mitochondrial adaptation during non-alcoholic fatty liver disease (NAFLD) include remodeling of ketogenic flux and sustained tricarboxylic acid (TCA) cycle activity, which are concurrent to onset of oxidative stress. Over 70% of obese humans have NAFLD and ketogenic diets are common weight loss strategies. However, the effectiveness of ketogenic diets toward alleviating NAFLD remains unclear. We hypothesized that chronic ketogenesis will worsen metabolic dysfunction and oxidative stress during NAFLD. Mice (C57BL/6) were kept (for 16-wks) on either a low-fat, high-fat, or high-fat diet supplemented with 1.5X branched chain amino acids (BCAAs) by replacing carbohydrate calories (ketogenic). The ketogenic diet induced hepatic lipid oxidation and ketogenesis, and produced multifaceted changes in flux through the individual steps of the TCA cycle. Higher rates of hepatic oxidative fluxes fueled by the ketogenic diet paralleled lower rates of de novo lipogenesis. Interestingly, this metabolic remodeling did not improve insulin resistance, but induced fibrogenic genes and inflammation in the liver. Under a chronic "ketogenic environment," the hepatocyte diverted more acetyl-CoA away from lipogenesis toward ketogenesis and TCA cycle, a milieu which can hasten oxidative stress and inflammation. In summary, chronic exposure to ketogenic environment during obesity and NAFLD has the potential to aggravate hepatic mitochondrial dysfunction.
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Affiliation(s)
| | - Marc McLeod
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Meghan Maguire
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD, USA
| | - Rohit Mahar
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Nathan Kattapuram
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD, USA
| | - Christine Zhang
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD, USA
| | - Chaitra Surugihalli
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD, USA
| | - Vaishna Muralidaran
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD, USA
| | - Kruthi Vavilikolanu
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD, USA
| | - Clayton E Mathews
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Nishanth E Sunny
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD, USA
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Nuclear Magnetic Resonance Measurement of Metabolic Flux Using 13C and 1H Signals. Methods Mol Biol 2019. [PMID: 31127544 DOI: 10.1007/978-1-4939-9488-5_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Metabolic flux modeling is a complementary technique to standard metabolomics/metabonomics as routinely practiced in biological systems. Here we outline carbon-13-based isotopomer analysis using nuclear magnetic resonance as the primary analytical technique. Isotopomer analysis produces relative rates of tricarboxylic acid cycle turnover. If these measures are normalized to O2 consumption, absolute rates can be inferred. The primary biological system targeted in this review is cell culture.
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Wang Y, Christopher BA, Wilson KA, Muoio D, McGarrah RW, Brunengraber H, Zhang GF. Propionate-induced changes in cardiac metabolism, notably CoA trapping, are not altered by l-carnitine. Am J Physiol Endocrinol Metab 2018; 315:E622-E633. [PMID: 30016154 PMCID: PMC6230704 DOI: 10.1152/ajpendo.00081.2018] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
High concentrations of propionate and its metabolites are found in several diseases that are often associated with the development of cardiac dysfunction, such as obesity, diabetes, propionic acidemia, and methylmalonic acidemia. In the present work, we employed a stable isotope-based metabolic flux approach to understand propionate-mediated perturbation of cardiac energy metabolism. Propionate led to accumulation of propionyl-CoA (increased by ~101-fold) and methylmalonyl-CoA (increased by 36-fold). This accumulation caused significant mitochondrial CoA trapping and inhibited fatty acid oxidation. The reduced energy contribution from fatty acid oxidation was associated with increased glucose oxidation. The enhanced anaplerosis of propionate and CoA trapping altered the pool sizes of tricarboxylic acid cycle (TCA) metabolites. In addition to being an anaplerotic substrate, the accumulation of proprionate-derived malate increased the recycling of malate to pyruvate and acetyl-CoA, which can enter the TCA for energy production. Supplementation of 3 mM l-carnitine did not relieve CoA trapping and did not reverse the propionate-mediated fuel switch. This is due to new findings that the heart appears to lack the specific enzyme catalyzing the conversion of short-chain (C3 and C4) dicarboxylyl-CoAs to dicarboxylylcarnitines. The discovery of this work warrants further investigation on the relevance of dicarboxylylcarnitines, especially C3 and C4 dicarboxylylcarnitines, in cardiac conditions such as heart failure.
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Affiliation(s)
- Yingxue Wang
- Department of Endocrinology and Metabolism, The First Affiliated Hospital, Jinan University , Guangzhou , China
- Sarah W. Stedman Nutrition and Metabolism Center & Duke Molecular Physiology Institute, Duke University , Durham, North Carolina
| | - Bridgette A Christopher
- Sarah W. Stedman Nutrition and Metabolism Center & Duke Molecular Physiology Institute, Duke University , Durham, North Carolina
- Department of Medicine, Duke University , Durham, North Carolina
| | - Kirkland A Wilson
- Department of Nutrition, Case Western Reserve University , Cleveland, Ohio
| | - Deborah Muoio
- Sarah W. Stedman Nutrition and Metabolism Center & Duke Molecular Physiology Institute, Duke University , Durham, North Carolina
- Department of Medicine, Duke University , Durham, North Carolina
| | - Robert W McGarrah
- Sarah W. Stedman Nutrition and Metabolism Center & Duke Molecular Physiology Institute, Duke University , Durham, North Carolina
- Department of Medicine, Duke University , Durham, North Carolina
| | - Henri Brunengraber
- Department of Nutrition, Case Western Reserve University , Cleveland, Ohio
| | - Guo-Fang Zhang
- Sarah W. Stedman Nutrition and Metabolism Center & Duke Molecular Physiology Institute, Duke University , Durham, North Carolina
- Department of Medicine, Duke University , Durham, North Carolina
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Lindsey ML, Gray GA, Wood SK, Curran-Everett D. Statistical considerations in reporting cardiovascular research. Am J Physiol Heart Circ Physiol 2018; 315:H303-H313. [PMID: 30028200 PMCID: PMC6139626 DOI: 10.1152/ajpheart.00309.2018] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The problem of inadequate statistical reporting is long standing and widespread in the biomedical literature, including in cardiovascular physiology. Although guidelines for reporting statistics have been available in clinical medicine for some time, there are currently no guidelines specific to cardiovascular physiology. To assess the need for guidelines, we determined the type and frequency of statistical tests and procedures currently used in the American Journal of Physiology-Heart and Circulatory Physiology. A PubMed search for articles published in the American Journal of Physiology-Heart and Circulatory Physiology between January 1, 2017, and October 6, 2017, provided a final sample of 146 articles evaluated for methods used and 38 articles for indepth analysis. The t-test and ANOVA accounted for 71% (212 of 300 articles) of the statistical tests performed. Of six categories of post hoc tests, Bonferroni and Tukey tests were used in 63% (62 of 98 articles). There was an overall lack in details provided by authors publishing in the American Journal of Physiology-Heart and Circulatory Physiology, and we compiled a list of recommended minimum reporting guidelines to aid authors in preparing manuscripts. Following these guidelines could substantially improve the quality of statistical reports and enhance data rigor and reproducibility.
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Affiliation(s)
- Merry L Lindsey
- Mississippi Center for Heart Research, Department of Physiology and Biophysics, University of Mississippi Medical Center , Jackson, Mississippi.,Research Service, G. V. (Sonny) Montgomery Veterans Affairs Medical Center , Jackson, Mississippi
| | - Gillian A Gray
- British Heart Foundation/University Centre for Cardiovascular Science, Edinburgh Medical School, University of Edinburgh , Edinburgh , United Kingdom
| | - Susan K Wood
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine , Columbia, South Carolina
| | - Douglas Curran-Everett
- Division of Biostatistics and Bioinformatics, National Jewish Health , Denver, Colorado.,Department of Biostatistics and Informatics, Colorado School of Public Health, University of Colorado Denver , Denver, Colorado
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Carvalho RA, Jarak I. Mitochondrial Bioenergetics by 13C-NMR Isotopomer Analysis. Methods Mol Biol 2018; 1782:229-247. [PMID: 29851003 DOI: 10.1007/978-1-4939-7831-1_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Metabolic reprogramming has been associated to a plethora of diseases, and there has been increased demand for methodologies able to determine the metabolic alterations that characterize the pathological states and help developing metabolically centered therapies. In this chapter, methodologies for monitoring TCA cycle turnover and its interaction with pyruvate cycling and anaplerotic reactions will be presented. These methodologies are based in the application of stable 13C isotope "tracers"/substrates and 13C-NMR isotopomer analysis of metabolic intermediates. These methodologies can be applied at several organizational levels, ranging from isolated organelles and organs to whole organisms/humans. For the sake of simplicity, only very simple and well-defined models will be presented, including isolated heart mitochondria and isolated perfused hearts and livers.
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Affiliation(s)
- Rui A Carvalho
- Department of Life Sciences, Faculty of Sciences and Technology, University of Coimbra, Coimbra, Portugal.
- Centre for Functional Ecology, University of Coimbra, Coimbra, Portugal.
| | - Ivana Jarak
- Centre for Functional Ecology, University of Coimbra, Coimbra, Portugal
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