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Päivärinta J, Anastasiou IA, Koivuviita N, Sharma K, Nuutila P, Ferrannini E, Solini A, Rebelos E. Renal Perfusion, Oxygenation and Metabolism: The Role of Imaging. J Clin Med 2023; 12:5141. [PMID: 37568543 PMCID: PMC10420088 DOI: 10.3390/jcm12155141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2023] [Revised: 08/02/2023] [Accepted: 08/03/2023] [Indexed: 08/13/2023] Open
Abstract
Thanks to technical advances in the field of medical imaging, it is now possible to study key features of renal anatomy and physiology, but so far poorly explored due to the inherent difficulties in studying both the metabolism and vasculature of the human kidney. In this narrative review, we provide an overview of recent research findings on renal perfusion, oxygenation, and substrate uptake. Most studies evaluating renal perfusion with positron emission tomography (PET) have been performed in healthy controls, and specific target populations like obese individuals or patients with renovascular disease and chronic kidney disease (CKD) have rarely been assessed. Functional magnetic resonance (fMRI) has also been used to study renal perfusion in CKD patients, and recent studies have addressed the kidney hemodynamic effects of therapeutic agents such as glucagon-like receptor agonists (GLP-1RA) and sodium-glucose co-transporter 2 inhibitors (SGLT2-i) in an attempt to characterise the mechanisms leading to their nephroprotective effects. The few available studies on renal substrate uptake are discussed. In the near future, these imaging modalities will hopefully become widely available with researchers more acquainted with them, gaining insights into the complex renal pathophysiology in acute and chronic diseases.
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Affiliation(s)
- Johanna Päivärinta
- Department of Medicine, Division of Nephrology, Turku University Hospital, 20521 Turku, Finland; (J.P.); (N.K.)
| | - Ioanna A. Anastasiou
- 1st Department of Propaedeutic and Internal Medicine, Medical School, National and Kapodistrian University of Athens, Laiko General Hospital, 11527 Athens, Greece;
| | - Niina Koivuviita
- Department of Medicine, Division of Nephrology, Turku University Hospital, 20521 Turku, Finland; (J.P.); (N.K.)
| | - Kanishka Sharma
- Department of Imaging, Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield S10 2TN, UK;
| | - Pirjo Nuutila
- Turku PET Centre, 20521 Turku, Finland;
- Department of Endocrinology, Turku University Hospital, 20521 Turku, Finland
| | - Ele Ferrannini
- CNR, Institute of Clinical Physiology, 56124 Pisa, Italy;
| | - Anna Solini
- Department of Surgical, Medical, Molecular and Critical Area Pathology, University of Pisa, 56124 Pisa, Italy;
| | - Eleni Rebelos
- Turku PET Centre, 20521 Turku, Finland;
- Department of Clinical and Experimental Medicine, University of Pisa, 56124 Pisa, Italy
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Cridland JM, Contino CE, Begun DJ. Selection and geography shape male reproductive tract transcriptomes in Drosophila melanogaster. Genetics 2023; 224:iyad034. [PMID: 36869688 PMCID: PMC10474930 DOI: 10.1093/genetics/iyad034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 01/25/2023] [Accepted: 02/20/2023] [Indexed: 03/05/2023] Open
Abstract
Transcriptome analysis of several animal clades suggests that male reproductive tract gene expression evolves quickly. However, the factors influencing the abundance and distribution of within-species variation, the ultimate source of interspecific divergence, are poorly known. Drosophila melanogaster, an ancestrally African species that has recently spread throughout the world and colonized the Americas in the last roughly 100 years, exhibits phenotypic and genetic latitudinal clines on multiple continents, consistent with a role for spatially varying selection in shaping its biology. Nevertheless, geographic expression variation in the Americas is poorly described, as is its relationship to African expression variation. Here, we investigate these issues through the analysis of two male reproductive tissue transcriptomes [testis and accessory gland (AG)] in samples from Maine (USA), Panama, and Zambia. We find dramatic differences between these tissues in differential expression between Maine and Panama, with the accessory glands exhibiting abundant expression differentiation and the testis exhibiting very little. Latitudinal expression differentiation appears to be influenced by the selection of Panama expression phenotypes. While the testis shows little latitudinal expression differentiation, it exhibits much greater differentiation than the accessory gland in Zambia vs American population comparisons. Expression differentiation for both tissues is non-randomly distributed across the genome on a chromosome arm scale. Interspecific expression divergence between D. melanogaster and D. simulans is discordant with rates of differentiation between D. melanogaster populations. Strongly heterogeneous expression differentiation across tissues and timescales suggests a complex evolutionary process involving major temporal changes in the way selection influences expression evolution in these organs.
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Affiliation(s)
- Julie M Cridland
- Department of Evolution and Ecology, University of California-Davis, Davis, CA 95616, USA
| | - Colin E Contino
- Department of Evolution and Ecology, University of California-Davis, Davis, CA 95616, USA
| | - David J Begun
- Department of Evolution and Ecology, University of California-Davis, Davis, CA 95616, USA
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3
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Kim J, Jo D, Yang SH, Joo CG, Whiting N, Pudakalakatti S, Seo H, Son HY, Min SJ, Bhattacharya P, Huh YM, Shim JH, Lee Y. 29Si Isotope-Enriched Silicon Nanoparticles for an Efficient Hyperpolarized Magnetic Resonance Imaging Probe. ACS APPLIED MATERIALS & INTERFACES 2021; 13:56923-56930. [PMID: 34793118 DOI: 10.1021/acsami.1c16617] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Silicon particles have garnered attention as promising biomedical probes for hyperpolarized 29Si magnetic resonance imaging and spectroscopy. However, due to the limited levels of hyperpolarization for nanosized silicon particles, microscale silicon particles have primarily been the focus of dynamic nuclear polarization (DNP) applications, including in vivo magnetic resonance imaging (MRI). To address these current challenges, we developed a facile synthetic method for partially 29Si-enriched porous silicon nanoparticles (NPs) (160 nm) and examined their usability in hyperpolarized 29Si MRI agents with enhanced signals in spectroscopy and imaging. Hyperpolarization characteristics, such as the build-up constant, the depolarization time (T1), and the overall enhancement of the 29Si-enriched silicon NPs (10 and 15%), were thoroughly investigated and compared with those of a naturally abundant NP (4.7%). During optimal DNP conditions, the 15% enriched silicon NPs showed more than 16-fold higher enhancements─far beyond the enrichment ratio─than the naturally abundant sample, further improving the signal-to-noise ratio in in vivo 29Si MRI. The 29Si-enriched porous silicon NPs used in this work are potentially capable to serve as drug-delivery vehicles in addition to hyperpolarized 29Si in vivo, further enabling their potential future applicability as a theragnostic platform.
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Affiliation(s)
- Jiwon Kim
- Department of Bionano Technology, Center for Bionano Intelligence Education and Research, Hanyang University, Ansan 15588, South Korea
| | - Donghyuk Jo
- Department of Bionano Technology, Center for Bionano Intelligence Education and Research, Hanyang University, Ansan 15588, South Korea
| | - Seung-Hyun Yang
- Department of Radiology, College of Medicine, Yonsei University, Seoul 03722, South Korea
- Interdisciplinary Program in Nanomedical Science and Technology, Nanomedical National Core Research Center, Yonsei University, Seoul 03722, South Korea
| | - Chan-Gyu Joo
- Severance Biomedical Science Institute, College of Medicine, Yonsei University, Seoul 03722, South Korea
| | - Nicholas Whiting
- Department of Physics & Astronomy, Rowan University, Glassboro, New Jersey 08028, United States
| | - Shivanand Pudakalakatti
- Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, Texas 77054, United States
| | - Hyeonglim Seo
- Department of Bionano Technology, Center for Bionano Intelligence Education and Research, Hanyang University, Ansan 15588, South Korea
| | - Hye Young Son
- Department of Radiology, College of Medicine, Yonsei University, Seoul 03722, South Korea
- Severance Biomedical Science Institute, College of Medicine, Yonsei University, Seoul 03722, South Korea
| | - Sun-Joon Min
- Department of Applied Chemistry, Hanyang University, Ansan 15588, South Korea
| | - Pratip Bhattacharya
- Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, Texas 77054, United States
| | - Yong-Min Huh
- Department of Radiology, College of Medicine, Yonsei University, Seoul 03722, South Korea
- Severance Biomedical Science Institute, College of Medicine, Yonsei University, Seoul 03722, South Korea
- YUHS-KRIBB Medical Convergence Research Institute, College of Medicine, Yonsei University, Seoul 03722, South Korea
- Department of Biochemistry & Molecular Biology, College of Medicine, Yonsei University, Seoul 03722, South Korea
| | - Jeong Hyun Shim
- Quantum Magnetic Imaging Team, Korea Research Institute of Standards and Science, Daejeon 34113, South Korea
| | - Youngbok Lee
- Department of Bionano Technology, Center for Bionano Intelligence Education and Research, Hanyang University, Ansan 15588, South Korea
- Department of Applied Chemistry, Hanyang University, Ansan 15588, South Korea
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Bertelsen LB, Hansen ESS, Sadowski T, Ruf S, Laustsen C. Hyperpolarized pyruvate to measure the influence of PKM2 activation on glucose metabolism in the healthy kidney. NMR IN BIOMEDICINE 2021; 34:e4583. [PMID: 34240478 DOI: 10.1002/nbm.4583] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 06/16/2021] [Accepted: 06/17/2021] [Indexed: 06/13/2023]
Abstract
The purpose of the current study was to investigate if hyperpolarized [1-13 C]pyruvate can inform us on the metabolic consequences for the kidney glucose metabolism upon treatment with the pyruvate kinase M2 (PKM2) activator TEPP-46, which has shown promise as a novel therapeutic target for diabetic nephropathy. A healthy male Wistar rat model was employed to study the conversion of [1-13 C]pyruvate to [1-13 C]lactate in the kidney 2 and 4 h after treatment with TEPP-46. All rats were scanned with hyperpolarized [1-13 C]pyruvate kidney MR and vital parameters and blood samples were taken after scanning. The PKM2 activator TEPP-46 increases the glycolytic activity in the kidneys, leading to an increased lactate production, as seen by hyperpolarized pyruvate-to-lactate conversion. The results are supported by an increase in blood lactate, a decreased blood glucose level and an increased pyruvate kinase (PK) activity. The metabolic changes observed in both kidneys following treatment with TEPP-46 are largely independent of renal function and could as such represent a new and extremely sensitive metabolic readout for future drugs targeting PKM2. These results warrant further studies in disease models to evaluate if [1-13 C]pyruvate-to-[1-13 C]lactate conversion can predict treatment outcome.
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Affiliation(s)
- Lotte Bonde Bertelsen
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | | | | | - Sven Ruf
- Sanofi-Aventis Deutschland GmbH, Frankfurt am Main, Germany
| | - Christoffer Laustsen
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
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5
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Bech SK, Qi H, Mariager CØ, Hansen ESS, Ilicak E, Zöllner FG, Laustsen C. The number of glomeruli and pyruvate metabolism is not strongly coupled in the healthy rat kidney. Magn Reson Med 2021; 87:896-903. [PMID: 34554602 DOI: 10.1002/mrm.29025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 08/23/2021] [Accepted: 09/07/2021] [Indexed: 11/10/2022]
Abstract
PURPOSE The number of glomeruli is different in men and women, as they also present different prevalence and progression of chronic kidney disease. A recent study has demonstrated a potential difference in renal metabolism between sexes, and a potential explanation could be the differences in glomeruli number. This study investigates the potential correlation between glomerular number and pyruvate metabolism in healthy kidneys. METHODS This study is an experimental study with rats (N = 12). We used cationized-ferritin MRI to visualize and count glomeruli and hyperpolarized [1-13 C]pyruvate to map the metabolism. Dynamic contrast-enhanced MRI was used to analyze kidney hemodynamics using gadolinium tracer. RESULTS Data showed no or subtle correlation between the number of glomeruli and the pyruvate metabolism. Minor differences were observed in the number of glomeruli (female = 24,509 vs. male = 26 350; p = .16), renal plasma flow (female = 606.6 vs. male= 455.7 ml/min/100 g; p = .18), and volume of distribution (female = 87.44 vs. male = 76.61 ml/100 ml; p = .54) between sexes. Mean transit time was significantly prolonged in males compared with females (female = 8.868 s vs. male = 10.63 s; p = .04). CONCLUSION No strong statistically significant correlation between the number of glomeruli and the pyruvate metabolism was found in healthy rat kidneys.
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Affiliation(s)
- Sabrina Kahina Bech
- MR Research Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Haiyun Qi
- MR Research Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | | | | | - Efe Ilicak
- Computer Assisted Clinical Medicine, Mannheim Institute for Intelligent Systems in Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Frank G Zöllner
- Computer Assisted Clinical Medicine, Mannheim Institute for Intelligent Systems in Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.,Cooperative Core Facility Animal Scanner ZI, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Christoffer Laustsen
- MR Research Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
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6
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Wen Y, Qi H, Østergaard Mariager C, Mose Nielsen P, Bonde Bertelsen L, Stødkilde-Jørgensen H, Laustsen C. Sex Differences in Kidney Function and Metabolism Assessed Using Hyperpolarized [1- 13C]Pyruvate Interleaved Spectroscopy and Nonspecific Imaging. ACTA ACUST UNITED AC 2021; 6:5-13. [PMID: 32280745 PMCID: PMC7138520 DOI: 10.18383/j.tom.2020.00022] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Metabolic sex differences have recently been shown to be particularly important in tailoring treatment strategies. Sex has a major effect on fat turnover rates and plasma lipid delivery in the body. Differences in kidney structure and transporters between male and female animals have been found. Here we investigated sex-specific renal pyruvate metabolic flux and whole-kidney functional status in age-matched healthy Wistar rats. Blood oxygenation level–dependent and dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) were used to assess functional status. Hyperpolarized [1-13C]pyruvate was used to assess the metabolic differences between male and female rats. Female rats had a 41% ± 3% and 41% ± 5% lower absolute body and kidney weight, respectively, than age-matched male rats. No difference was seen between age-matched male and female rats in the kidney-to-body weight ratio. A 56% ± 11% lower lactate production per mL/100 mL/min was found in female rats than in age-matched male rats measured by hyperpolarized magnetic resonance and DCE MRI. Female rats had a 33% ± 11% higher glomerular filtration rate than age-matched male rats measured by DCE MRI. A similar renal oxygen tension (T2*) was found between age-matched male and female rats as shown by blood oxygenation level–dependent MRI. The results were largely independent of the pyruvate volume and the difference in body weight. This study shows an existing metabolic difference between kidneys in age-matched male and female rats, which indicates that sex differences need to be considered when performing animal experiments.
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Affiliation(s)
- Yibo Wen
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark; and.,The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Henan, China
| | - Haiyun Qi
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark; and
| | | | - Per Mose Nielsen
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark; and
| | - Lotte Bonde Bertelsen
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark; and
| | | | - Christoffer Laustsen
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark; and
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Vaeggemose M, F. Schulte R, Laustsen C. Comprehensive Literature Review of Hyperpolarized Carbon-13 MRI: The Road to Clinical Application. Metabolites 2021; 11:metabo11040219. [PMID: 33916803 PMCID: PMC8067176 DOI: 10.3390/metabo11040219] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 03/31/2021] [Accepted: 04/01/2021] [Indexed: 01/02/2023] Open
Abstract
This review provides a comprehensive assessment of the development of hyperpolarized (HP) carbon-13 metabolic MRI from the early days to the present with a focus on clinical applications. The status and upcoming challenges of translating HP carbon-13 into clinical application are reviewed, along with the complexity, technical advancements, and future directions. The road to clinical application is discussed regarding clinical needs and technological advancements, highlighting the most recent successes of metabolic imaging with hyperpolarized carbon-13 MRI. Given the current state of hyperpolarized carbon-13 MRI, the conclusion of this review is that the workflow for hyperpolarized carbon-13 MRI is the limiting factor.
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Affiliation(s)
- Michael Vaeggemose
- GE Healthcare, 2605 Brondby, Denmark;
- MR Research Centre, Department of Clinical Medicine, Aarhus University, 8000 Aarhus, Denmark
| | | | - Christoffer Laustsen
- MR Research Centre, Department of Clinical Medicine, Aarhus University, 8000 Aarhus, Denmark
- Correspondence:
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8
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Hyperpolarized Carbon ( 13C) MRI of the Kidney: Experimental Protocol. Methods Mol Biol 2021. [PMID: 33476019 DOI: 10.1007/978-1-0716-0978-1_29] [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
Alterations in renal metabolism are associated with both physiological and pathophysiologic events. The existing noninvasive analytic tools including medical imaging have limited capability for investigating these processes, which potentially limits current understanding of kidney disease and the precision of its clinical diagnosis. Hyperpolarized 13C MRI is a new medical imaging modality that can capture changes in the metabolic processing of certain rapidly metabolized substrates, as well as changes in kidney function. Here we describe experimental protocols for renal metabolic [1-13C]pyruvate and functional 13C-urea imaging step-by-step. These methods and protocols are useful for investigating renal blood flow and function as well as the renal metabolic status of rodents in vivo under various experimental (patho)physiological conditions.This chapter is based upon work from the COST Action PARENCHIMA, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers. This experimental protocol is complemented by two separate chapters describing the basic concept and data analysis.
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Elbæk Madsen K, Mariager CØ, Duvald CS, Hansen ESS, Bertelsen LB, Pedersen M, Pedersen LH, Uldbjerg N, Laustsen C. Ex Vivo Human Placenta Perfusion, Metabolic and Functional Imaging for Obstetric Research-A Feasibility Study. ACTA ACUST UNITED AC 2020; 5:333-338. [PMID: 31893231 PMCID: PMC6935991 DOI: 10.18383/j.tom.2019.00016] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Placenta metabolism is closely linked to pregnancy outcome, and few modalities are currently available for studying the human placenta. Here, we aimed to investigate a novel ex vivo human placenta perfusion system for metabolic imaging using hyperpolarized [1-13C]pyruvate. The metabolic effects of 3 different human placentas were investigated using functional and metabolic magnetic resonance imaging. The placenta glucose metabolism and hemodynamics were characterized with hyperpolarized [1-13C]pyruvate magnetic resonance imaging and by dynamic contrast-enhanced (DCE) imaging. Hyperpolarized [1-13C]pyruvate showed a decrease in the 13C-lactate/13C-pyruvate ratio from the highest to the lowest metabolic active placenta. The metabolic profile was complemented by a more homogenous distributed hemodynamic response, with a longer mean transit time and higher blood volume. This study shows different placenta metabolic and hemodynamic features associated with the placenta functional status using hyperpolarized magnetic resonance ex vivo. This study supports further studies using ex vivo metabolic imaging of the placenta alterations associated with pregnancy complications.
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Affiliation(s)
- Katrine Elbæk Madsen
- Department of Clinical Medicine, MR-Research Centre, Aarhus University, Aarhus, Denmark.,Department of Clinical Medicine, Comparative Medicine Laboratory, Aarhus University, Aarhus, Denmark; and
| | | | - Christina S Duvald
- Department of Clinical Medicine, Comparative Medicine Laboratory, Aarhus University, Aarhus, Denmark; and
| | | | - Lotte Bonde Bertelsen
- Department of Clinical Medicine, MR-Research Centre, Aarhus University, Aarhus, Denmark
| | - Michael Pedersen
- Department of Clinical Medicine, Comparative Medicine Laboratory, Aarhus University, Aarhus, Denmark; and
| | - Lars Henning Pedersen
- Department of Gynaecology and Obstetrics, Aarhus University Hospital and Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Niels Uldbjerg
- Department of Gynaecology and Obstetrics, Aarhus University Hospital and Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Christoffer Laustsen
- Department of Clinical Medicine, MR-Research Centre, Aarhus University, Aarhus, Denmark
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Laustsen C, Nielsen PM, Qi H, Løbner MH, Palmfeldt J, Bertelsen LB. Hyperpolarized [1,4- 13C]fumarate imaging detects microvascular complications and hypoxia mediated cell death in diabetic nephropathy. Sci Rep 2020; 10:9650. [PMID: 32541797 PMCID: PMC7295762 DOI: 10.1038/s41598-020-66265-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 05/18/2020] [Indexed: 12/14/2022] Open
Abstract
Today, there is a general lack of prognostic biomarkers for development of renal disease and in particular diabetic nephropathy. Increased glycolytic activity, lactate accumulation and altered mitochondrial oxygen utilization are hallmarks of diabetic kidney disease. Fumarate hydratase activity has been linked to mitochondrial dysfunction as well as activation of the hypoxia inducible factor, induction of apoptosis and necrosis. Here, we investigate fumarate hydratase activity in biofluids in combination with the molecular imaging probe, hyperpolarized [1,4-13C2]fumarate, to identify the early changes associated with hemodynamics and cell death in a streptozotocin rat model of type 1 diabetes. We found a significantly altered hemodynamic signature of [1,4-13C2]fumarate in the diabetic kidneys as well as an systemic increased metabolic conversion of fumarate-to-malate, indicative of increased cell death associated with progression of diabetes, while little to no renal specific conversion was observed. This suggest apoptosis as the main cause of cell death in the diabetic kidney. This is likely resulting from an increased reactive oxygen species production following uncoupling of the electron transport chain at complex II. The mechanism coupling the enzyme leakage and apoptotic phenotype is hypoxia inducible factor independent and seemingly functions as a protective mechanism in the kidney cells.
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Affiliation(s)
- Christoffer Laustsen
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.
| | - Per Mose Nielsen
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Haiyun Qi
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Mette Hadberg Løbner
- Research Unit for Molecular Medicine, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Johan Palmfeldt
- Research Unit for Molecular Medicine, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Lotte Bonde Bertelsen
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
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11
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Nielsen PM, Qi H, Bertelsen LB, Laustsen C. Metabolic reprogramming associated with progression of renal ischemia reperfusion injury assessed with hyperpolarized [1- 13C]pyruvate. Sci Rep 2020; 10:8915. [PMID: 32488151 PMCID: PMC7265284 DOI: 10.1038/s41598-020-65816-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Accepted: 05/11/2020] [Indexed: 01/02/2023] Open
Abstract
Acute kidney injury is a major clinical challenge affecting as many as 1 percent of all hospitalized patients. Currently it is not possible to accurately stratify and predict the outcome of the individual patient. Increasing evidence supports metabolic reprogramming as a potential target for new biomarkers. Hyperpolarized [1-13C]pyruvate imaging is a promising new tool for evaluating the metabolic status directly in the kidneys. We here investigate the prognostic potential of hyperpolarized [1-13C]pyruvate in the setting of acute kidney injury in a rodent model of ischemia reperfusion. A significant correlation was found between the intra-renal metabolic profile 24 hours after reperfusion and 7 days after injury induction, as well as a correlation with the conventional plasma creatinine biomarker of renal function and markers of renal injury. This leads to a possible outcome prediction of renal function and injury development from a metabolic profile measured in vivo. The results support human translation of this new technology to renal patients as all experiements have been performed using clinical MRI equipment.
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Affiliation(s)
- Per Mose Nielsen
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Haiyun Qi
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Lotte Bonde Bertelsen
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Christoffer Laustsen
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.
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12
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Nielsen PM, Mariager CØ, Mølmer M, Sparding N, Genovese F, Karsdal MA, Nørregaard R, Bertelsen LB, Laustsen C. Hyperpolarized [1- 13 C] alanine production: A novel imaging biomarker of renal fibrosis. Magn Reson Med 2020; 84:2063-2073. [PMID: 32452096 DOI: 10.1002/mrm.28326] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 04/27/2020] [Accepted: 04/28/2020] [Indexed: 12/15/2022]
Abstract
PURPOSE Renal tubulointerstitial fibrosis is strongly linked to the progressive decline of renal function seen in chronic kidney disease. State-of-the-art noninvasive diagnostic modalities are currently unable to detect the earliest changes associated with the onset of fibrosis. This study was undertaken to evaluate the potential for detecting the earliest alterations in fibrogenesis using a biofluid-based method and metabolic hyperpolarized [1-13 C]pyruvate imaging. METHODS We evaluated renal fibrosis in a combined ischemia reperfusion-induced and streptozotocin-induced diabetic nephropathy rodent model by hyperpolarized [1-13 C]pyruvate MRI and correlated the metabolic MRI parameters with biomarkers of fibrosis measured on renal tissue and plasma/urine. RESULTS The hyperglycemic rats experienced maladaptive injury repair after the ischemic insults, as shown by the elevation in the injury markers kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin. Renal function was significantly impaired in the ischemic hyperglycemic kidney, as seen in the reduced perfusion and single-kidney glomerular filtration rate. A deranged energy metabolism was detected in the ischemic hyperglycemic kidney, as seen in the reduced fractional perfusion of lactate. Renal fibrosis biomarkers correlated significantly with the alanine production. CONCLUSION Hyperpolarized carbon-13 MRI provides a promising approach to assess renal fibrosis in an animal model of fibrotic chronic kidney disease. In particular, the metabolic supply of amino acids for fibrogenesis (alanine production) correlates well with biomarkers of fibrosis. Thus, [1-13 C]pyruvate-to-[1-13 C]alanine conversion might be a candidate for noninvasive assessment of renal fibrogenesis.
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Affiliation(s)
- Per Mose Nielsen
- MR Research Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | | | - Maria Mølmer
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | | | | | | | - Rikke Nørregaard
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Lotte Bonde Bertelsen
- MR Research Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Christoffer Laustsen
- MR Research Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
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13
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Pedersen M, Ursprung S, Jensen JD, Jespersen B, Gallagher F, Laustsen C. Hyperpolarised 13C-MRI metabolic and functional imaging: an emerging renal MR diagnostic modality. MAGMA (NEW YORK, N.Y.) 2020; 33:23-32. [PMID: 31782036 DOI: 10.1007/s10334-019-00801-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 10/21/2019] [Accepted: 11/12/2019] [Indexed: 12/11/2022]
Abstract
Magnetic resonance imaging (MRI) is a well-established modality for assessing renal morphology and function, as well as changes that occur during disease. However, the significant metabolic changes associated with renal disease are more challenging to assess with MRI. Hyperpolarized carbon-13 MRI is an emerging technique which provides an opportunity to probe metabolic alterations at high sensitivity by providing an increase in the signal-to-noise ratio of 20,000-fold or more. This review will highlight the current status of hyperpolarised 13C-MRI and its translation into the clinic and how it compares to metabolic measurements provided by competing technologies such as positron emission tomography (PET).
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Affiliation(s)
| | - Stephan Ursprung
- Department of Radiology, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK
| | - Jens Dam Jensen
- Department of Renal Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - Bente Jespersen
- Department of Renal Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - Ferdia Gallagher
- Department of Radiology, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK
| | - Christoffer Laustsen
- MR Research Centre, Department of Clinical Medicine, Aarhus University Hospital, Palle Juul Jensens Boulevard, 8200, Aarhus N, Denmark.
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14
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Laustsen C, Lipsø K, Østergaard JA, Nielsen PM, Bertelsen LB, Flyvbjerg A, Pedersen M, Palm F, Ardenkjær-Larsen JH. High Intrarenal Lactate Production Inhibits the Renal Pseudohypoxic Response to Acutely Induced Hypoxia in Diabetes. ACTA ACUST UNITED AC 2020; 5:239-247. [PMID: 31245545 PMCID: PMC6588198 DOI: 10.18383/j.tom.2019.00003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Intrarenal hypoxia develops within a few days after the onset of insulinopenic diabetes in an experimental animal model (ie, a model of type-1 diabetes). Although diabetes-induced hypoxia results in increased renal lactate formation, mitochondrial function is well maintained, a condition commonly referred to as pseudohypoxia. However, the metabolic effects of significantly elevated lactate levels remain unclear. We therefore investigated in diabetic animals the response to acute intrarenal hypoxia in the presence of high renal lactate formation to delineate mechanistic pathways and compare these findings to healthy control animals. Hyperpolarized 13C-MRI and blood oxygenation level–dependent 1H-MRI was used to investigate the renal metabolism of [1-13C]pyruvate and oxygenation following acutely altered oxygen content in the breathing gas in a streptozotocin rat model of type-1 diabetes with and without insulin treatment and compared with healthy control rats. The lactate signal in the diabetic kidney was reduced by 12%–16% during hypoxia in diabetic rats irrespective of insulin supplementation. In contrast, healthy controls displayed the well-known Pasteur effect manifested as a 10% increased lactate signal following reduction of oxygen in the inspired air. Reduced expression of the monocarboxyl transporter-4 may account for altered response to hypoxia in diabetes with a high intrarenal pyruvate-to-lactate conversion. Reduced intrarenal lactate formation in response to hypoxia in diabetes shows the existence of a different metabolic phenotype, which is independent of insulin, as insulin supplementation was unable to affect the pyruvate-to-lactate conversion in the diabetic kidney.
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Affiliation(s)
- Christoffer Laustsen
- Department of Clinical Medicine, MR Research Centre, Aarhus University, Aarhus, Denmark
| | - Kasper Lipsø
- Danish Research Centre for Magnetic Resonance, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark.,Department of Electrical Engineering, Technical University of Denmark, Kgs Lyngby, Denmark
| | - Jakob Appel Østergaard
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - Per Mose Nielsen
- Department of Clinical Medicine, MR Research Centre, Aarhus University, Aarhus, Denmark
| | - Lotte Bonde Bertelsen
- Department of Clinical Medicine, MR Research Centre, Aarhus University, Aarhus, Denmark
| | - Allan Flyvbjerg
- Steno Diabetes Center Copenhagen, The Capital Region of Denmark, Gentofte, Denmark.,University of Copenhagen, Copenhagen, Denmark
| | - Michael Pedersen
- Department of Clinical Medicine, MR Research Centre, Aarhus University, Aarhus, Denmark
| | - Fredrik Palm
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden; and
| | - Jan Henrik Ardenkjær-Larsen
- Danish Research Centre for Magnetic Resonance, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark.,Department of Electrical Engineering, Technical University of Denmark, Kgs Lyngby, Denmark.,GE Healthcare, Copenhagen, Denmark
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15
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Technical recommendations for clinical translation of renal MRI: a consensus project of the Cooperation in Science and Technology Action PARENCHIMA. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2019; 33:131-140. [PMID: 31628564 PMCID: PMC7021737 DOI: 10.1007/s10334-019-00784-w] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2019] [Revised: 09/23/2019] [Accepted: 10/01/2019] [Indexed: 12/14/2022]
Abstract
Purpose The potential of renal MRI biomarkers has been increasingly recognised, but clinical translation requires more standardisation. The PARENCHIMA consensus project aims to develop and apply a process for generating technical recommendations on renal MRI. Methods A task force was formed in July 2018 focused on five methods. A draft process for attaining consensus was distributed publicly for consultation and finalised at an open meeting (Prague, October 2018). Four expert panels completed surveys between October 2018 and March 2019, discussed results and refined the surveys at a face-to-face meeting (Aarhus, March 2019) and completed a second round (May 2019). Results A seven-stage process was defined: (1) formation of expert panels; (2) definition of the context of use; (3) literature review; (4) collection and comparison of MRI protocols; (5) consensus generation by an approximate Delphi method; (6) reporting of results in vendor-neutral and vendor-specific terms; (7) ongoing review and updating. Application of the process resulted in 166 consensus statements. Conclusion The process generated meaningful technical recommendations across very different MRI methods, while allowing for improvement and refinement as open issues are resolved. The results are likely to be widely supported by the renal MRI community and thereby promote more harmonisation.
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16
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Hansen RB, Sánchez‐Heredia JD, Bøgh N, Hansen ESS, Laustsen C, Hanson LG, Ardenkjær‐Larsen JH. Coil profile estimation strategies for parallel imaging with hyperpolarized
13
C MRI. Magn Reson Med 2019; 82:2104-2117. [DOI: 10.1002/mrm.27892] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 06/12/2019] [Accepted: 06/13/2019] [Indexed: 01/16/2023]
Affiliation(s)
- Rie B. Hansen
- Department of Health Technology Technical University of Denmark Kongens Lyngby Denmark
| | | | - Nikolaj Bøgh
- MR Research Centre Aarhus University Aarhus Denmark
| | | | | | - Lars G. Hanson
- Department of Health Technology Technical University of Denmark Kongens Lyngby Denmark
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research Copenhagen University Hospital Hvidovre Copenhagen Denmark
| | - Jan H. Ardenkjær‐Larsen
- Department of Health Technology Technical University of Denmark Kongens Lyngby Denmark
- GE Healthcare Brøndby Denmark
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17
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Mariager CO, Lindhardt J, Nielsen PM, Schulte RF, Ringgaard S, Laustsen C. Fractional Perfusion: A Simple Semi-Parametric Measure for Hyperpolarized 13C MR. IEEE TRANSACTIONS ON RADIATION AND PLASMA MEDICAL SCIENCES 2019. [DOI: 10.1109/trpms.2019.2905724] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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18
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Kodama Y, Hyodo F, Yamato M, Yasukawa K, Minami Y, Sonoda N, Ogawa Y, Ichikawa K, Inoguchi T. Dynamic nuclear polarization magnetic resonance imaging and the oxygen-sensitive paramagnetic agent OX63 provide a noninvasive quantitative evaluation of kidney hypoxia in diabetic mice. Kidney Int 2019; 96:787-792. [PMID: 31345583 DOI: 10.1016/j.kint.2019.04.034] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2018] [Revised: 04/21/2019] [Accepted: 04/25/2019] [Indexed: 12/24/2022]
Abstract
Renal hypoxia may play an important role in the progression of diabetic nephropathy. However, tools that noninvasively and quantitatively measure oxygen tension in the kidney are lacking. Here, we evaluated the feasibility of a noninvasive and quantitative imaging technique using dynamic nuclear polarization magnetic resonance imaging (DNP-MRI) in combination with the oxygen-sensitive paramagnetic agent OX63 for measuring oxygen tension in the kidney. Our results demonstrate that the DNP-MRI technique can yield quantitative maps of oxygen tension in the mouse renal cortex. Using this procedure, we also showed that oxygen tension was less elevated in the renal cortex of both streptozotocin-induced type 1 diabetic mice and db/db mice, a model of type 2 diabetes, than in the renal cortex of age-matched control mice of each respective model. Oxygen tension in streptozotocin-exposed mice was significantly improved by insulin treatment. Thus, the noninvasive and quantitative DNP-MRI technique appears to be useful for studying the pathophysiological role of hypoxia.
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Affiliation(s)
- Yoshimi Kodama
- Department of Internal Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Fuminori Hyodo
- Innovation Center for Medical Redox Navigation, Kyushu University, Fukuoka, Japan; Frontier Science for Imaging, Department of Radiology, School of Medicine Gifu University, Gifu, Japan; Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Mayumi Yamato
- Innovation Center for Medical Redox Navigation, Kyushu University, Fukuoka, Japan; Physical Chemistry for Life Science Laboratory, Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Keiji Yasukawa
- Innovation Center for Medical Redox Navigation, Kyushu University, Fukuoka, Japan; Laboratory of Advanced Pharmacology, Daiichi University of Pharmacy, Fukuoka, Japan
| | - Yohei Minami
- Department of Internal Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Noriyuki Sonoda
- Department of Internal Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; Innovation Center for Medical Redox Navigation, Kyushu University, Fukuoka, Japan
| | - Yoshihiro Ogawa
- Department of Internal Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; Department of Molecular Endocrinology and Metabolism, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan; CREST, Japan Agency for Medical Research and Development, Tokyo, Japan
| | - Kazuhiro Ichikawa
- Innovation Center for Medical Redox Navigation, Kyushu University, Fukuoka, Japan; Department of Biophysical Chemistry, Faculty of Pharmaceutical Sciences, Nagasaki International University, Nagasaki, Japan
| | - Toyoshi Inoguchi
- Innovation Center for Medical Redox Navigation, Kyushu University, Fukuoka, Japan; Fukuoka City Health Promotion Support Center, Fukuoka City, Japan.
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19
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Wang Z, Nielsen PM, Laustsen C, Bertelsen LB. Metabolic consequences of lactate dehydrogenase inhibition by oxamate in hyperglycemic proximal tubular cells. Exp Cell Res 2019; 378:51-56. [PMID: 30836064 DOI: 10.1016/j.yexcr.2019.03.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 02/27/2019] [Accepted: 03/01/2019] [Indexed: 01/14/2023]
Abstract
Diabetic kidney disease (DKD) is associated with altered metabolic patterns, leading to increased lactate production even in the presence of sufficient oxygen supply. Studies have shown hyperglycemia to be an important factor in determining development of DKD. Here we explore the metabolic consequences of lactate dehydrogenase (LDH) inhibition exerted by the LDH inhibitor, oxamate, in the isolated rat renal proximal tubular cells (NRK-52E) under hyperglycemic conditions. Cells treated with oxamate (100 mM) for 24 h, with or without high D-glucose (25 mM) load, were investigated with hyperpolarized [1-13C]pyruvate in a 1T NMR system. Respiratory measurements using an oxygen microsensor system was conducted. Oxamate treatment of cells with or without the presences of high D-glucose, reduced the lactate production/accumulation with 36.5% or 22.5% respectively. Reduced proliferation, hypertrophic effects, as well as elevated vascular endothelial growth factor (VEGF) expression in the NRK-52E cells were found. The increased glycolytic flux in high D-glucose cultured NRK-52E cells resulted in an upregulation of the cellular oxygen consumption rate upon treatment with oxamate. Our findings suggested that in vitro cultured NRK-52E cells exposed to hyperglycemic conditions, could redirect the glycolytic flux towards oxidative phosphorylation by LDH inhibition. This link between aerobic and anaerobic metabolism may be determined by the redox balance (NAD+/NADH ratio). In conclusion, hyperglycemic conditions and oxamate treatment alters the metabolic phenotype of NRK-52E cells towards increased oxygen utilization mediated by a decreased NAD+/NADH ratio, which in turn decreases cell proliferation/survival.
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Affiliation(s)
- Zhimin Wang
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark; Division of Endocrinology and Metabolic Diseases, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Per Mose Nielsen
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Christoffer Laustsen
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Lotte Bonde Bertelsen
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.
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20
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Bertelsen LB, Nielsen PM, Qi H, Mariager CØ, Lindhardt J, Laustsen C. Renal Energy Metabolism Following Acute Dichloroacetate and 2,4-Dinitrophenol Administration: Assessing the Cumulative Action with Hyperpolarized [1- 13C]Pyruvate MRI. ACTA ACUST UNITED AC 2018; 4:105-109. [PMID: 30320210 PMCID: PMC6173791 DOI: 10.18383/j.tom.2018.00022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Numerous patient groups receive >1 medication and as such represent a potential point of improvement in today's healthcare setup, as the combined or cumulative effects are difficult to monitor in an individual patient. Here we show the ability to monitor the pharmacological effect of 2 classes of medications sequentially, namely, 2,4-dinitrophenol, a mitochondrial uncoupler, and dichloroacetate, a pyruvate dehydrogenase kinase inhibitor, both targeting the oxygen-dependent energy metabolism. We show that although the 2 drugs target 2 different metabolic pathways connected ultimately to oxygen metabolism, we could distinguish the 2 in vivo by using hyperpolarized [1-13C]pyruvate magnetic resonance imaging. A statistically significantly different pyruvate dehydrogenase flux was observed by reversing the treatment order of 2,4-dinitrophenol and dichloroacetate. The significance of this study is the demonstration of the ability to monitor the metabolic cumulative effects of 2 distinct therapeutics on an in vivo organ level using hyperpolarized magnetic resonance imaging.
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Affiliation(s)
- Lotte Bonde Bertelsen
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Per Mose Nielsen
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Haiyun Qi
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | | | - Jakob Lindhardt
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Christoffer Laustsen
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
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21
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Riis-Vestergaard MJ, Breining P, Pedersen SB, Laustsen C, Stødkilde-Jørgensen H, Borghammer P, Jessen N, Richelsen B. Evaluation of Active Brown Adipose Tissue by the Use of Hyperpolarized [1- 13C]Pyruvate MRI in Mice. Int J Mol Sci 2018; 19:ijms19092597. [PMID: 30200469 PMCID: PMC6164296 DOI: 10.3390/ijms19092597] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 08/21/2018] [Accepted: 08/30/2018] [Indexed: 02/07/2023] Open
Abstract
The capacity to increase energy expenditure makes brown adipose tissue (BAT) a putative target for treatment of metabolic diseases such as obesity. Presently, investigation of BAT in vivo is mainly performed by fluoro-d-glucose positron emission tomography (FDG PET)/CT. However, non-radioactive methods that add information on, for example, substrate metabolism are warranted. Thus, the aim of this study was to evaluate the potential of hyperpolarized [1-13C]pyruvate Magnetic Resonance Imaging (HP-MRI) to determine BAT activity in mice following chronic cold exposure. Cold (6 °C) and thermo-neutral (30 °C) acclimated mice were scanned with HP-MRI for assessment of the interscapular BAT (iBAT) activity. Comparable mice were scanned with the conventional method FDG PET/MRI. Finally, iBAT was evaluated for gene expression and protein levels of the specific thermogenic marker, uncoupling protein 1 (UCP1). Cold exposure increased the thermogenic capacity 3–4 fold (p < 0.05) as measured by UCP1 gene and protein analysis. Furthermore, cold exposure as compared with thermo-neutrality increased iBAT pyruvate metabolism by 5.5-fold determined by HP-MRI which is in good agreement with the 5-fold increment in FDG uptake (p < 0.05) measured by FDG PET/MRI. iBAT activity is detectable in mice using HP-MRI in which potential changes in intracellular metabolism may add useful information to the conventional FDG PET studies. HP-MRI may also be a promising radiation-free tool for repetitive BAT studies in humans.
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Affiliation(s)
- Mette Ji Riis-Vestergaard
- Department of Internal Medicine and Endocrinology, Aarhus University Hospital, 8200 Aarhus N, Denmark.
- Institute of Clinical Medicine, Aarhus University, 8200 Aarhus N, Denmark.
| | - Peter Breining
- Department of Internal Medicine and Endocrinology, Aarhus University Hospital, 8200 Aarhus N, Denmark.
- Institute of Clinical Medicine, Aarhus University, 8200 Aarhus N, Denmark.
| | - Steen Bønløkke Pedersen
- Department of Internal Medicine and Endocrinology, Aarhus University Hospital, 8200 Aarhus N, Denmark.
- Institute of Clinical Medicine, Aarhus University, 8200 Aarhus N, Denmark.
| | - Christoffer Laustsen
- MR Research Center, Institute of Clinical Medicine, Aarhus University, 8200 Aarhus N, Denmark.
| | | | - Per Borghammer
- Department of Nuclear Medicine & PET Centre, Aarhus University Hospital, 8000 Aarhus C, Denmark.
| | - Niels Jessen
- Department of Clinical Pharmacology, Aarhus University Hospital, 8000 Aarhus C, Denmark.
| | - Bjørn Richelsen
- Department of Internal Medicine and Endocrinology, Aarhus University Hospital, 8200 Aarhus N, Denmark.
- Institute of Clinical Medicine, Aarhus University, 8200 Aarhus N, Denmark.
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22
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Tougaard RS, Hansen ESS, Laustsen C, Lindhardt J, Schroeder M, Bøtker HE, Kim WY, Wiggers H, Stødkilde‐Jørgensen H. Acute hypertensive stress imaged by cardiac hyperpolarized [1‐
13
C]pyruvate magnetic resonance. Magn Reson Med 2018. [DOI: 10.1002/mrm.27164] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Rasmus Stilling Tougaard
- Department of CardiologyAarhus University Hospital Denmark
- MR Research Centre, Department of Clinical MedicineAarhus University Denmark
| | - Esben Søvsø Szocska Hansen
- MR Research Centre, Department of Clinical MedicineAarhus University Denmark
- Danish Diabetes Academy Denmark
| | | | - Jakob Lindhardt
- MR Research Centre, Department of Clinical MedicineAarhus University Denmark
| | - Marie Schroeder
- MR Research Centre, Department of Clinical MedicineAarhus University Denmark
| | | | - Won Yong Kim
- Department of CardiologyAarhus University Hospital Denmark
- MR Research Centre, Department of Clinical MedicineAarhus University Denmark
| | - Henrik Wiggers
- Department of CardiologyAarhus University Hospital Denmark
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23
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Qi H, Nielsen PM, Schroeder M, Bertelsen LB, Palm F, Laustsen C. Acute renal metabolic effect of metformin assessed with hyperpolarised MRI in rats. Diabetologia 2018; 61:445-454. [PMID: 28936623 DOI: 10.1007/s00125-017-4445-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 08/04/2017] [Indexed: 01/07/2023]
Abstract
AIMS/HYPOTHESIS Metformin inhibits hepatic mitochondrial glycerol phosphate dehydrogenase, thereby increasing cytosolic lactate and suppressing gluconeogenesis flux in the liver. This inhibition alters cytosolic and mitochondrial reduction-oxidation (redox) potential, which has been reported to protect organ function in several disease states including diabetes. In this study, we investigated the acute metabolic and functional changes induced by metformin in the kidneys of both healthy and insulinopenic Wistar rats used as a model of diabetes. METHODS Diabetes was induced by intravenous injection of streptozotocin, and kidney metabolism in healthy and diabetic animals was investigated 4 weeks thereafter using hyperpolarised 13C-MRI, Clark-type electrodes and biochemical analysis. RESULTS Metformin increased renal blood flow, but did not change total kidney oxygen consumption. In healthy rat kidneys, metformin increased [1-13C]lactate production and reduced mitochondrial [1-13C]pyruvate oxidation (decreased the 13C-bicarbonate/[1-13C]pyruvate ratio) within 30 min of administration. Corresponding alterations to indices of mitochondrial, cytosolic and whole-cell redox potential were observed. Pyruvate oxidation was maintained in the diabetic rats, suggesting that the diabetic state abrogates metabolic reprogramming caused by metformin. CONCLUSIONS/INTERPRETATION This study demonstrates that metformin-induced acute metabolic alterations in healthy kidneys favoured anaerobic metabolism at the expense of aerobic metabolism. The results suggest that metformin directly alters the renal redox state, with elevated renal cytosolic redox states as well as decreased mitochondrial redox state. These findings suggest redox biology as a novel target to eliminate the renal complications associated with metformin treatment in individuals with impaired renal function.
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Affiliation(s)
- Haiyun Qi
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Palle Juul-Jensens Boulevard 99, 8200, Aarhus N, Denmark
| | - Per M Nielsen
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Palle Juul-Jensens Boulevard 99, 8200, Aarhus N, Denmark
| | - Marie Schroeder
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Palle Juul-Jensens Boulevard 99, 8200, Aarhus N, Denmark
| | - Lotte B Bertelsen
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Palle Juul-Jensens Boulevard 99, 8200, Aarhus N, Denmark
| | - Fredrik Palm
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Christoffer Laustsen
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Palle Juul-Jensens Boulevard 99, 8200, Aarhus N, Denmark.
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24
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Mikkelsen EFR, Mariager CØ, Nørlinger T, Qi H, Schulte RF, Jakobsen S, Frøkiær J, Pedersen M, Stødkilde-Jørgensen H, Laustsen C. Hyperpolarized [1- 13C]-acetate Renal Metabolic Clearance Rate Mapping. Sci Rep 2017; 7:16002. [PMID: 29167446 PMCID: PMC5700138 DOI: 10.1038/s41598-017-15929-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 11/03/2017] [Indexed: 01/02/2023] Open
Abstract
11C-acetate is a positron emission tomography (PET) tracer of oxidative metabolism, whereas hyperpolarized 13C-acetate can be used in magnetic resonance imaging (MRI) for investigating specific metabolic processes. The aims of this study were to examine if the kinetic formalism of 11C-acetate PET in the kidneys is comparable to that of 13C-acetate MRI, and to compare the dynamic metabolic information of hyperpolarized 13C-acetate MRI with that obtained with 11C-acetate PET. Rats were examined with dynamic hyperpolarized 13C-acetate MRI or 11C-acetate PET before and after intravenous injection of furosemide, a loop diuretic known to alter both the hemodynamics and oxygen consumption in the kidney. The metabolic clearance rates (MCR) were estimated and compared between the two modalities experimentally in vivo and in simulations. There was a clear dependency on the mean transit time and MCR for both 13C-acetate and 11C-acetate following furosemide administration, while no dependencies on the apparent renal perfusion were observed. This study demonstrated that hyperpolarized 13C-acetate MRI is feasible for measurements of the intrarenal energetic demand via the MCR, and that the quantitative measures are correlated with those measured by 11C-acetate PET, even though the temporal window is more than 30 times longer with 11C-acetate.
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Affiliation(s)
- Emmeli F R Mikkelsen
- MR Research Centre, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, 8200, Aarhus N, Denmark.,Comparative Medicine Lab, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, 8200, Aarhus N, Denmark
| | | | - Thomas Nørlinger
- MR Research Centre, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, 8200, Aarhus N, Denmark.,Comparative Medicine Lab, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, 8200, Aarhus N, Denmark
| | - Haiyun Qi
- MR Research Centre, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, 8200, Aarhus N, Denmark
| | - Rolf F Schulte
- GE healthcare, Freisinger Landstraße 50, 85748, Munich, Germany
| | - Steen Jakobsen
- Department of Nuclear Medicine and PET Center, Aarhus University Hospital, Nørrebrogade, 8000, Aarhus C, Denmark
| | - Jørgen Frøkiær
- Department of Nuclear Medicine and PET Center, Aarhus University Hospital, Nørrebrogade, 8000, Aarhus C, Denmark
| | - Michael Pedersen
- Comparative Medicine Lab, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, 8200, Aarhus N, Denmark
| | - Hans Stødkilde-Jørgensen
- MR Research Centre, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, 8200, Aarhus N, Denmark
| | - Christoffer Laustsen
- MR Research Centre, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, 8200, Aarhus N, Denmark.
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25
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Patinha D, Pijacka W, Paton JFR, Koeners MP. Cooperative Oxygen Sensing by the Kidney and Carotid Body in Blood Pressure Control. Front Physiol 2017; 8:752. [PMID: 29046642 PMCID: PMC5632678 DOI: 10.3389/fphys.2017.00752] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 09/15/2017] [Indexed: 12/13/2022] Open
Abstract
Oxygen sensing mechanisms are vital for homeostasis and survival. When oxygen levels are too low (hypoxia), blood flow has to be increased, metabolism reduced, or a combination of both, to counteract tissue damage. These adjustments are regulated by local, humoral, or neural reflex mechanisms. The kidney and the carotid body are both directly sensitive to falls in the partial pressure of oxygen and trigger reflex adjustments and thus act as oxygen sensors. We hypothesize a cooperative oxygen sensing function by both the kidney and carotid body to ensure maintenance of whole body blood flow and tissue oxygen homeostasis. Under pathological conditions of severe or prolonged tissue hypoxia, these sensors may become continuously excessively activated and increase perfusion pressure chronically. Consequently, persistence of their activity could become a driver for the development of hypertension and cardiovascular disease. Hypoxia-mediated renal and carotid body afferent signaling triggers unrestrained activation of the renin angiotensin-aldosterone system (RAAS). Renal and carotid body mediated responses in arterial pressure appear to be synergistic as interruption of either afferent source has a summative effect of reducing blood pressure in renovascular hypertension. We discuss that this cooperative oxygen sensing system can activate/sensitize their own afferent transduction mechanisms via interactions between the RAAS, hypoxia inducible factor and erythropoiesis pathways. This joint mechanism supports our view point that the development of cardiovascular disease involves afferent nerve activation.
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Affiliation(s)
- Daniela Patinha
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences, University of Bristol, Bristol, United Kingdom.,Institute of Biomedical and Clinical Science, University of Exeter Medical School, University of Exeter, Exeter, United Kingdom
| | - Wioletta Pijacka
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences, University of Bristol, Bristol, United Kingdom
| | - Julian F R Paton
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences, University of Bristol, Bristol, United Kingdom
| | - Maarten P Koeners
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences, University of Bristol, Bristol, United Kingdom.,Institute of Biomedical and Clinical Science, University of Exeter Medical School, University of Exeter, Exeter, United Kingdom
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26
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Østergaard Mariager C, Nielsen PM, Qi H, Schroeder M, Bertelsen LB, Laustsen C. Can Hyperpolarized 13C-Urea be Used to Assess Glomerular Filtration Rate? A Retrospective Study. ACTA ACUST UNITED AC 2017; 3:146-152. [PMID: 30042978 PMCID: PMC6024438 DOI: 10.18383/j.tom.2017.00010] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
This study investigated a simple method for calculating the single-kidney glomerular filtration rate (GFR) using dynamic hyperpolarized 13C-urea magnetic resonance (MR) renography. A retrospective data analysis was applied to renal hyperpolarized 13C-urea MR data acquired from control rats, prediabetic nephropathy rats, and rats in which 1 kidney was subjected to ischemia-reperfusion. Renal blood flow was determined by the model-free bolus differentiation method, GFR was determined using the Baumann–Rudin model method. Reference single-kidney and total GFRs were measured by plasma creatinine content and compared to 1H dynamic contrast-enhanced estimated GFR and fluorescein isothiocyanate-inulin clearance GFR estimation. In healthy and prediabetic nephropathy rats, single-kidney hyperpolarized 13C-urea GFR was estimated to be 2.5 ± 0.7 mL/min in good agreement with both gold-standard inulin clearance GFR (2.7 ± 1.2 ml/min) and 1H dynamic contrast-enhanced estimated GFR (1.8 ± 0.8 mL/min), as well as plasma creatinine measurements and literature findings. Following ischemia-reperfusion, hyperpolarized 13C-urea revealed a significant reduction in single-kidney GFR of 57% compared with the contralateral kidney. Hyperpolarized 13C MR could be a promising tool for accurate determination of GFR. The model-free renal blood flow and arterial input function-insensitive GFR estimations are simple to implement and warrant further translational adaptation.
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Affiliation(s)
| | - Per Mose Nielsen
- Department of Clinical Medicine, MR Research Centre, Aarhus University, Aarhus, Denmark
| | - Haiyun Qi
- Department of Clinical Medicine, MR Research Centre, Aarhus University, Aarhus, Denmark
| | - Marie Schroeder
- Department of Clinical Medicine, MR Research Centre, Aarhus University, Aarhus, Denmark
| | - Lotte Bonde Bertelsen
- Department of Clinical Medicine, MR Research Centre, Aarhus University, Aarhus, Denmark
| | - Christoffer Laustsen
- Department of Clinical Medicine, MR Research Centre, Aarhus University, Aarhus, Denmark
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27
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Nørlinger TS, Nielsen PM, Qi H, Mikkelsen E, Hansen K, Schmidt NH, Pedersen M, Agger P, Palm F, Laustsen C. Hyperbaric oxygen therapy reduces renal lactate production. Physiol Rep 2017; 5:e13217. [PMID: 28336821 PMCID: PMC5371573 DOI: 10.14814/phy2.13217] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Revised: 02/26/2017] [Accepted: 02/28/2017] [Indexed: 01/27/2023] Open
Abstract
Intrarenal hypoxia is an acknowledged factor contributing to the development of diabetic nephropathy. Hyperbaric oxygen (HBO) therapy is a well-known adjuvant treatment for several medical conditions, such as decompression sickness, infections, and wound healing. The underlying metabolic response of HBO is largely unknown. In this study, we investigated the effect of HBO on the intrarenal metabolic alteration in diabetes. Hyperpolarized [1-13C]pyruvate MRI was performed to assess intrarenal energy metabolism in normoglycemic controls and short-term (2 weeks) streptozotocin-induced diabetic rats with and without HBO for five consecutive days. HBO therapy blunted intrarenal lactate production, 3 days after the therapy, in both normoglycemic controls and diabetic rats without affecting either lactate dehydrogenase mRNA expression or activity. HBO therapy reduced lactate formation in both normoglycemic and hyperglycemic rats. These findings support hyperpolarized [1-13C]pyruvate MRI as a novel method for monitoring HBO therapy via the pyruvate to lactate conversion.
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Affiliation(s)
- Thomas S Nørlinger
- Department of Clinical Medicine, MR Research Centre, Aarhus University, Aarhus, Denmark
| | - Per Mose Nielsen
- Department of Clinical Medicine, MR Research Centre, Aarhus University, Aarhus, Denmark
| | - Haiyun Qi
- Department of Clinical Medicine, MR Research Centre, Aarhus University, Aarhus, Denmark
| | - Emmeli Mikkelsen
- Department of Clinical Medicine, MR Research Centre, Aarhus University, Aarhus, Denmark
| | - Kasper Hansen
- Department of Clinical Medicine, Comparative Medicine Lab, Aarhus University, Aarhus, Denmark
| | - Nikolaj H Schmidt
- Department of Clinical Medicine, Comparative Medicine Lab, Aarhus University, Aarhus, Denmark
| | - Michael Pedersen
- Department of Clinical Medicine, MR Research Centre, Aarhus University, Aarhus, Denmark
- Department of Clinical Medicine, Comparative Medicine Lab, Aarhus University, Aarhus, Denmark
| | - Peter Agger
- Department of Pediatrics, Aarhus University Hospital, Aarhus, Denmark
- Department of Clinical Medicine, Comparative Medicine Lab, Aarhus University, Aarhus, Denmark
| | - Fredrik Palm
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Christoffer Laustsen
- Department of Clinical Medicine, MR Research Centre, Aarhus University, Aarhus, Denmark
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28
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Fumarase activity: an in vivo and in vitro biomarker for acute kidney injury. Sci Rep 2017; 7:40812. [PMID: 28094329 PMCID: PMC5240145 DOI: 10.1038/srep40812] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 12/12/2016] [Indexed: 11/08/2022] Open
Abstract
Renal ischemia/reperfusion injury (IRI) is a leading cause of acute kidney injury (AKI), and at present, there is a lack of reliable biomarkers that can diagnose AKI and measure early progression because the commonly used methods cannot evaluate single-kidney IRI. Hyperpolarized [1,4-13C2]fumarate conversion to [1,4-13C2]malate by fumarase has been proposed as a measure of necrosis in rat tumor models and in chemically induced AKI rats. Here we show that the degradation of cell membranes in connection with necrosis leads to elevated fumarase activity in plasma and urine and secondly that hyperpolarized [1,4-13C2]malate production 24 h after reperfusion correlates with renal necrosis in a 40-min unilateral ischemic rat model. Fumarase activity screening on bio-fluids can detect injury severity, in bilateral as well as unilateral AKI models, differentiating moderate and severe AKI as well as short- and long-term AKI. Furthermore after verification of renal injury by bio-fluid analysis the precise injury location can be monitored by in vivo measurements of the fumarase activity non-invasively by hyperpolarized [1,4-13C]fumarate MR imaging. The combined in vitro and in vivo biomarker of AKI responds to the essential requirements for a new reliable biomarker of AKI.
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29
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Laustsen C. Hyperpolarized 13C Magnetic Resonance Treatment Response Monitoring: A New Paradigm for Multiorgan Metabolic Assessment of Pharmacological Interventions? Diabetes 2016; 65:3529-3531. [PMID: 27879402 DOI: 10.2337/dbi16-0055] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Christoffer Laustsen
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
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30
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Hansen ESS, Stewart NJ, Wild JM, Stødkilde-Jørgensen H, Laustsen C. Hyperpolarized 13 C, 15 N 2 -Urea MRI for assessment of the urea gradient in the porcine kidney. Magn Reson Med 2016; 76:1895-1899. [PMID: 27670826 DOI: 10.1002/mrm.26483] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 08/10/2016] [Accepted: 09/07/2016] [Indexed: 12/24/2022]
Abstract
PURPOSE A decline in cortico-medullary osmolality gradient of the kidney may serve as an early indicator of pathological disruption of the tubular reabsorption process. The purpose of this study was to investigate the feasibility of hyperpolarized 13 C,15 N2 -urea MRI as a biomarker of renal function in healthy porcine kidneys resembling the human physiology. METHODS Five healthy female Danish domestic pigs (weight 30 kg) were scanned at 3 Tesla (T) using a 13 C 3D balanced steady-state MR pulse sequence following injection of hyperpolarized 13 C,15 N2 -urea via a femoral vein catheter. Images were acquired at different time points after urea injection, and following treatment with furosemide. RESULTS A gradient in cortico-medullary urea was observed with an intramedullary accumulation 75 s after injection of hyperpolarized 13 C,15 N2 -urea, whereas images acquired at earlier time points postinjection were dominated by cortical perfusion. Furosemide treatment resulted in an increased urea accumulation in the cortical space, leading to a reduction of the medullary-to-cortical signal ratio of 49%. CONCLUSION This study demonstrates that hyperpolarized 13 C,15 N2 -urea MRI is capable of identifying the intrarenal accumulation of urea and can differentiate acute renal functional states in multipapillary kidneys, highlighting the potential for human translation. Magn Reson Med 76:1895-1899, 2016. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Esben S S Hansen
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.,Danish Diabetes Academy, Odense, Denmark
| | - Neil J Stewart
- Academic Unit of Radiology, University of Sheffield, Sheffield, UK
| | - Jim M Wild
- Academic Unit of Radiology, University of Sheffield, Sheffield, UK
| | | | - Christoffer Laustsen
- MR Research Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
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