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DeGrado TR, Pandey MK, Belanger AP, Basuli F, Bansal A, Wang S. Noninvasive evaluation of fat-carbohydrate metabolic switching in heart and contracting skeletal muscle. Am J Physiol Endocrinol Metab 2019; 316:E251-E259. [PMID: 30512988 PMCID: PMC6397361 DOI: 10.1152/ajpendo.00323.2018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The ability of heart and skeletal muscle (SM) to switch between fat and carbohydrate oxidation is of high interest in the study of metabolic diseases and exercise physiology. Positron emission tomography (PET) imaging with the glucose analog 2-[18F]fluoro-2-deoxy-glucose (18F-FDG) provides a noninvasive means to quantitate glucose metabolic rates. However, evaluation of fatty acid oxidation (FAO) rates by PET has been limited by the lack of a suitable FAO probe. We have developed a metabolically trapped oleate analog, ( Z)-18-[18F]fluoro-4-thia-octadec-9-enoate (18F-FTO), and investigated the feasibility of using 18F-FTO and 18F-FDG to measure FAO and glucose uptake, respectively, in heart and SM of rats in vivo. To enhance the metabolic rates in SM, the vastus lateralis (VL) muscle was electrically stimulated in fasted rats for 30 min before and 30 min following radiotracer injection. The responses of radiotracer uptake patterns to pharmacological inhibition of FAO were assessed by pretreatment of the rats with the carnitine palmitoyl-transferase-1 (CPT-1) inhibitor sodium 2-[5-(4-chlorophenyl)-pentyl]oxirane-2-carboxylate (POCA). Small-animal PET images and biodistribution data with 18F-FTO and 18F-FDG demonstrated profound metabolic switching for energy provision in the myocardium from exogenous fatty acids to glucose in control and CPT-1-inhibited rats, respectively. Uptake of both radiotracers was low in unstimulated SM. In stimulated VL muscle, 18F-FTO and 18F-FDG uptakes were increased 4.4- and 28-fold, respectively, and CPT-1 inhibition only affected 18F-FTO uptake (66% decrease). 18F-FTO is a FAO-dependent PET probe that may allow assessment of energy substrate metabolic switching in conjunction with 18F-FDG and other metabolic probes.
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Affiliation(s)
- Timothy R DeGrado
- Department of Radiology, Mayo Clinic , Rochester, Minnesota
- Brigham and Women's Hospital, Harvard Medical School , Boston, Massachusetts
| | - Mukesh K Pandey
- Department of Radiology, Mayo Clinic , Rochester, Minnesota
- Brigham and Women's Hospital, Harvard Medical School , Boston, Massachusetts
| | | | - Falguni Basuli
- Brigham and Women's Hospital, Harvard Medical School , Boston, Massachusetts
| | - Aditya Bansal
- Department of Radiology, Mayo Clinic , Rochester, Minnesota
- Brigham and Women's Hospital, Harvard Medical School , Boston, Massachusetts
| | - Shuyan Wang
- Brigham and Women's Hospital, Harvard Medical School , Boston, Massachusetts
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Honka H, Hannukainen JC, Tarkia M, Karlsson H, Saunavaara V, Salminen P, Soinio M, Mikkola K, Kudomi N, Oikonen V, Haaparanta-Solin M, Roivainen A, Parkkola R, Iozzo P, Nuutila P. Pancreatic metabolism, blood flow, and β-cell function in obese humans. J Clin Endocrinol Metab 2014; 99:E981-90. [PMID: 24527718 DOI: 10.1210/jc.2013-4369] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
CONTEXT Glucolipotoxicity is believed to induce pancreatic β-cell dysfunction in obesity. Previously, it has not been possible to study pancreatic metabolism and blood flow in humans. OBJECTIVE The objective of the study was to investigate whether pancreatic metabolism and blood flow are altered in obesity using positron emission tomography (PET). In the preclinical part, the method was validated in animals. DESIGN This was a cross-sectional study. SETTING The study was conducted in a clinical research center. PARTICIPANTS Human studies consisted of 52 morbidly obese and 25 healthy age-matched control subjects. Validation experiments were done with rodents and pigs. INTERVENTIONS PET and magnetic resonance imaging studies using a glucose analog ([(18)F]fluoro-2-deoxy-d-glucose), a palmitate analog [14(R,S)-[(18)F]fluoro-6-thia-heptadecanoic acid], and radiowater ([(15)O]H2O) were performed. In animals, a comparison between ex vivo and in vivo data was performed. MAIN OUTCOME MEASURES Pancreatic glucose/fatty acid (FA) uptake, fat accumulation, and blood flow parameters of β-cell function were measured. RESULTS PET proved to be a feasible method to measure pancreatic metabolism. Compared with healthy participants, obese participants had elevated pancreatic FA uptake (P < .0001), more fat accumulation (P = .0001), lowered glucose uptake both during fasting and euglycemic hyperinsulinemia, and blunted blood flow (P < .01) in the pancreas. Blood flow, FA uptake, and fat accumulation were negatively associated with multiple markers of β-cell function. CONCLUSIONS Obesity leads to changes in pancreatic energy metabolism with a substrate shift from glucose to FAs. In morbidly obese humans, impaired pancreatic blood flow may contribute to β-cell dysfunction and in the pathogenesis of type 2 diabetes.
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Affiliation(s)
- Henri Honka
- Turku PET Centre (H.H., J.C.H., M.T., H.K., V.S., K.M., V.O., M.H.-S., A.R., R.P., P.N.), University of Turku, Turku 20520, Finland; Division of Digestive Surgery and Urology (P.S.) and Department of Endocrinology (P.N., M.S.), Turku University Hospital, Turku 20520, Finland; Faculty of Medicine (N.K.), University of Kagawa, Kagawa 760-0016, Japan; Department of Radiology (R.P.), University of Tampere, Tampere 33014, Finland; Institute of Biomedical Engineering (P.I.), National Research Council, 35128 Padua, Italy; and Institute of Clinical Physiology (P.I.), National Research Council, 56124 Pisa, Italy
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Honka H, Mäkinen J, Hannukainen JC, Tarkia M, Oikonen V, Teräs M, Fagerholm V, Ishizu T, Saraste A, Stark C, Vähäsilta T, Salminen P, Kirjavainen A, Soinio M, Gastaldelli A, Knuuti J, Iozzo P, Nuutila P. Validation of [18F]fluorodeoxyglucose and positron emission tomography (PET) for the measurement of intestinal metabolism in pigs, and evidence of intestinal insulin resistance in patients with morbid obesity. Diabetologia 2013; 56:893-900. [PMID: 23334481 DOI: 10.1007/s00125-012-2825-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Accepted: 12/17/2012] [Indexed: 01/09/2023]
Abstract
AIMS/HYPOTHESIS The role of the intestine in the pathogenesis of metabolic diseases is gaining much attention. We therefore sought to validate, using an animal model, the use of positron emission tomography (PET) in the estimation of intestinal glucose uptake (GU), and thereafter to test whether intestinal insulin-stimulated GU is altered in morbidly obese compared with healthy human participants. METHODS In the validation study, pigs were imaged using [(18)F]fluorodeoxyglucose ([(18)F]FDG) and the image-derived data were compared with corresponding ex vivo measurements in tissue samples and with arterial-venous differences in glucose and [(18)F]FDG levels. In the clinical study, GU was measured in different regions of the intestine in lean (n = 8) and morbidly obese (n = 8) humans at baseline and during euglycaemic hyperinsulinaemia. RESULTS PET- and ex vivo-derived intestinal values were strongly correlated and most of the fluorine-18-derived radioactivity was accumulated in the mucosal layer of the gut wall. In the gut wall of pigs, insulin promoted GU as determined by PET, the arterial-venous balance or autoradiography. In lean human participants, insulin increased GU from the circulation in the duodenum (from 1.3 ± 0.6 to 3.1 ± 1.1 μmol [100 g](-1) min(-1), p < 0.05) and in the jejunum (from 1.1 ± 0.7 to 3.0 ± 1.5 μmol [100 g](-1) min(-1), p < 0.05). Obese participants failed to show any increase in insulin-stimulated GU compared with fasting values (NS). CONCLUSIONS/INTERPRETATION Intestinal GU can be quantified in vivo by [(18)F]FDG PET. Intestinal insulin resistance occurs in obesity before the deterioration of systemic glucose tolerance.
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Affiliation(s)
- H Honka
- Turku PET Centre, University of Turku, PL 52, FIN-20520 Turku, Finland
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Xiong G, Paul C, Todica A, Hacker M, Bartenstein P, Böning G. Noninvasive image derived heart input function for CMRglc measurements in small animal slow infusion FDG PET studies. Phys Med Biol 2012; 57:8041-59. [PMID: 23160517 DOI: 10.1088/0031-9155/57/23/8041] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Absolute quantitation of the cerebral metabolic rate for glucose (CMRglc) can be obtained in positron emission tomography (PET) studies when serial measurements of the arterial [(18)F]-fluoro-deoxyglucose (FDG) input are available. Since this is not always practical in PET studies of rodents, there has been considerable interest in defining an image-derived input function (IDIF) by placing a volume of interest (VOI) within the left ventricle of the heart. However, spill-in arising from trapping of FDG in the myocardium often leads to progressive contamination of the IDIF, which propagates to underestimation of the magnitude of CMRglc. We therefore developed a novel, non-invasive method for correcting the IDIF without scaling to a blood sample. To this end, we first obtained serial arterial samples and dynamic FDG-PET data of the head and heart in a group of eight anaesthetized rats. We fitted a bi-exponential function to the serial measurements of the IDIF, and then used the linear graphical Gjedde-Patlak method to describe the accumulation in myocardium. We next estimated the magnitude of myocardial spill-in reaching the left ventricle VOI by assuming a Gaussian point-spread function, and corrected the measured IDIF for this estimated spill-in. Finally, we calculated parametric maps of CMRglc using the corrected IDIF, and for the sake of comparison, relative to serial blood sampling from the femoral artery. The uncorrected IDIF resulted in 20% underestimation of the magnitude of CMRglc relative to the gold standard arterial input method. However, there was no bias with the corrected IDIF, which was robust to the variable extent of myocardial tracer uptake, such that there was a very high correlation between individual CMRglc measurements using the corrected IDIF with gold-standard arterial input results. Based on simulation, we furthermore find that electrocardiogram-gating, i.e. ECG-gating is not necessary for IDIF quantitation using our approach.
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Affiliation(s)
- Guoming Xiong
- Department of Nuclear Medicine, Ludwig-Maximilians-University of Munich, Munich, Germany.
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Skovgaard D, Kjaer A, Heinemeier KM, Brandt-Larsen M, Madsen J, Kjaer M. Use of cis-[18F]fluoro-proline for assessment of exercise-related collagen synthesis in musculoskeletal connective tissue. PLoS One 2011; 6:e16678. [PMID: 21347251 PMCID: PMC3037959 DOI: 10.1371/journal.pone.0016678] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Accepted: 12/23/2010] [Indexed: 01/28/2023] Open
Abstract
Protein turnover in collagen rich tissue is influenced by exercise, but can only with difficulty be studied in vivo due to use of invasive procedure. The present study was done to investigate the possibility of applying the PET-tracer, cis-[18F]fluoro-proline (cis-Fpro), for non-invasive assessment of collagen synthesis in rat musculoskeletal tissues at rest and following short-term (3 days) treadmill running. Musculoskeletal collagen synthesis was studied in rats at rest and 24 h post-exercise. At each session, rats were PET scanned at two time points following injection of cis-FPro: (60 and 240 min p.i). SUV were calculated for Achilles tendon, calf muscle and tibial bone. The PET-derived results were compared to mRNA expression of collagen type I and III. Tibial bone had the highest SUV that increased significantly (p<0.001) from the early (60 min) to the late (240 min) PET scan, while SUV in tendon and muscle decreased (p<0.001). Exercise had no influence on SUV, which was contradicted by an increased gene expression of collagen type I and III in muscle and tendon. The clearly, visible uptake of cis-Fpro in the collagen-rich musculoskeletal tissues is promising for multi-tissue studies in vivo. The tissue-specific differences with the highest basal uptake in bone are in accordance with earlier studies relying on tissue incorporation of isotopic-labelled proline. A possible explanation of the failure to demonstrate enhanced collagen synthesis following exercise, despite augmented collagen type I and III transcription, is that SUV calculations are not sensitive enough to detect minor changes in collagen synthesis. Further studies including kinetic compartment modeling must be performed to establish whether cis-Fpro can be used for non-invasive in-vivo assessment of exercise-induced changes in musculoskeletal collagen synthesis.
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Affiliation(s)
- Dorthe Skovgaard
- Institute of Sports Medicine Copenhagen, Bispebjerg Hospital and Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
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Skovgaard D, Kjaer M, El-Ali H, Kjaer A. 18F-Fluorodeoxyglucose and PET/CT for noninvasive study of exercise-induced glucose uptake in rat skeletal muscle and tendon. Eur J Nucl Med Mol Imaging 2009; 36:859-68. [DOI: 10.1007/s00259-008-1020-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2008] [Accepted: 11/16/2008] [Indexed: 10/21/2022]
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Nakao R, Okada M, Inoue O, Fukumura T, Suzuki K. Combining high-performance liquid chromatography-positron detection and on-line microdialysis for animal metabolism study of positron emission tomography probes. J Chromatogr A 2008; 1203:193-7. [DOI: 10.1016/j.chroma.2008.07.049] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2008] [Revised: 07/10/2008] [Accepted: 07/17/2008] [Indexed: 10/21/2022]
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Iozzo P, Jarvisalo MJ, Kiss J, Borra R, Naum GA, Viljanen A, Viljanen T, Gastaldelli A, Buzzigoli E, Guiducci L, Barsotti E, Savunen T, Knuuti J, Haaparanta-Solin M, Ferrannini E, Nuutila P. Quantification of liver glucose metabolism by positron emission tomography: validation study in pigs. Gastroenterology 2007; 132:531-42. [PMID: 17258736 DOI: 10.1053/j.gastro.2006.12.040] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2006] [Accepted: 11/16/2006] [Indexed: 12/21/2022]
Abstract
BACKGROUND & AIMS The liver is inaccessible to organ balance measurements in humans. To validate [(18)F]fluorodeoxyglucose ([(18)F]FDG) positron emission tomography (PET) in the quantification of hepatic glucose uptake (HGU), we determined [(18)F]FDG modeling parameters, lumped constant (LC), and input functions (single arterial versus dual). METHODS Anesthetized pigs were studied during fasting (n = 6), physiologic (n = 4), and supraphysiologic (n = 4) hyperinsulinemia. PET was performed with C(15)O (blood pool) and [(18)F]FDG (glucose uptake). 6,6-Deuterated glucose ([(2)H]G) was coinjected with [(18)F]FDG and blood collected from the carotid artery and portal and hepatic veins to compute LC as ratio between tracers fractional extraction. HGU was estimated from PET images and ex vivo from high-performance liquid chromatography measurements of liver [(18)F]FDG versus [(18)F]FDG-6-phosphate and [(18)F]-glycogen. Endogenous glucose production was measured with [(2)H]G and hepatic blood flow by flowmeters. RESULTS HGU was increased in hyperinsulinemia versus fasting (P < .05). Fractional extraction of [(18)F]FDG and [(2)H]G was similar (not significant), intercorrelated (r = 0.98, P < .0001), and equally higher during hyperinsulinemia than fasting (P <or= .05), with an LC of 0.98 +/- 0.10 and 1.18 +/- 0.26, respectively. [(18)F]FDG-PET modeling provided HGU values that did not differ from, and were correlated with, those from ex vivo measurements (r = 0.61, P <or= .02); proportional estimates of liver perfusion and endogenous glucose production were also obtained. Single and dual input functions produced strongly intercorrelated results (r > 0.95, P < .0001), with a modest underestimation of HGU by the former. CONCLUSIONS [(18)F]FDG-PET-derived parameters provide accurate quantification of HGU and estimates of liver perfusion and glucose production. In the liver, LC of [(18)F]FDG is nearly unitary. Using a single arterial input introduces only a small error in estimation of HGU.
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Haaparanta M, Grönroos T, Eskola O, Bergman J, Solin O. Planar chromatographic analysis and quantification of short-lived radioactive metabolites from microdialysis fractions. J Chromatogr A 2006; 1108:136-9. [PMID: 16445924 DOI: 10.1016/j.chroma.2005.12.107] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2005] [Revised: 12/22/2005] [Accepted: 12/27/2005] [Indexed: 11/18/2022]
Abstract
A sensitive radiochromatographic method for the quantitative determination of compounds labelled with short-lived beta-emitting radionuclides in microdialysates is described. The method is well suited for microdialysis (MD) samples, which have small volumes and low concentrations of compounds. An 18F-labelled (beta+; T(1/2)=109.8 min) radiopharmaceutical, (1R,2S)-4-[18F]fluorometaraminol (FMR), was injected intravenously into rats, and microdialysis fractions were then collected from the blood at 15 min intervals. Fractions were analyzed for FMR and its radioactive metabolites by planar chromatography combined with digital photostimulated luminescence autoradiography. The lowest detectable 18F-radioactivity was 0.24 Bq/application and the limit of quantification was 0.31 Bq/application with 4-16 h exposure. The method was found to be highly sensitive and linear in the range of 0.1 Bq-2 kBq. This method thus allows the quantification of beta-emitting radiopharmaceuticals in sequential microdialysis fractions with good time-resolution.
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Affiliation(s)
- Merja Haaparanta
- Turku PET Centre, Medicity Research Laboratory/PET Preclinical Imaging, Tykistokatu 6A, FI 20520 Turku, Finland.
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Plock N, Kloft C. Microdialysis—theoretical background and recent implementation in applied life-sciences. Eur J Pharm Sci 2005; 25:1-24. [PMID: 15854796 DOI: 10.1016/j.ejps.2005.01.017] [Citation(s) in RCA: 181] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2004] [Revised: 01/20/2005] [Accepted: 01/21/2005] [Indexed: 11/26/2022]
Abstract
In the past decade microdialysis has become a method of choice in the study of unbound tissue concentrations of both endogenous and exogenous substances. Microdialysis has been shown to offer information about substances directly at the site of action while being well tolerable and safe. The large variety of its field of application has been demonstrated. However, a few challenges have to be met to make this method generally applicable in routine applications. This review will provide an overview over theoretical aspects that have to be considered during the implementation of microdialysis. Moreover, a comparison between microdialysis and other tissue sampling techniques will demonstrate advantages and limitations of the methods mentioned. Subsequently, it will present a critical synopsis of a variety of scientific/biomedical applications of this method with emphasis on the most recent literature, focussing on target tissues while giving examples of substances examined. It is concluded that microdialysis will be of great value in future investigations of pharmacokinetics, pharmacodynamics and in monitoring of disease status and progression.
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Affiliation(s)
- Nele Plock
- Department of Clinical Pharmacy, Institute of Pharmacy, Freie Universitaet Berlin, Kelchstr. 31, D-12169 Berlin, Germany
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