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Agnes RS, Traughber BJ, Muzic RF. Development of a selective novel fluorescent substrate for sodium-dependent transporters. Life Sci 2024; 351:122847. [PMID: 38880166 DOI: 10.1016/j.lfs.2024.122847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 06/07/2024] [Accepted: 06/13/2024] [Indexed: 06/18/2024]
Abstract
AIM To synthesize, characterize, and validate 6FGA, a fluorescent glucose modified with a Cyanine5.5 at carbon-6 position, for probing the function of sodium-dependent glucose transporters, SGLT1 and SGLT2. MAIN METHODS The synthesis of fluorescent glucose analogue was achieved through "click chemistry" of Cyanine5.5-alkyne and 6-azido-6-deoxy-d-glucose. Cell system studies were conducted to characterize the in vivo transport properties. KEY FINDINGS Optical analyses revealed that 6FGA displayed similar spectral profiles to Cyanine5.5 in DMSO, allowing for concentration determination, thus supporting its utility in quantitative kinetic studies within biological assays. Uptake studies in cell system SGLT models, LLC-PK1 and HEK293 cells, exhibited concentration and time-dependent behavior, indicating saturation at specific concentrations and durations which are hallmarks of transported-mediated uptake. The results of cytotoxicity assays suggested cell viability at micromolar concentrations, enabling usage in assays for at least 1 h without significant toxicity. The dependence of 6FGA uptake on sodium, the co-transported cation, was demonstrated in LLC-PK1 and HEK293 cells. Fluorescence microscopy confirmed intracellular localization of 6FGA, particularly near the nucleus. Competition studies revealed that glucose tends to weakly reduce 6FGA uptake, although the effect did not achieve statistical significance. Assessments using standard SGLT and GLUT inhibitors highlighted 6FGA's sensitivity for probing SGLT-mediated transport. SIGNIFICANCE 6FGA is a new fluorescent glucose analog offering advantages over existing probes due to its improved photophysical properties, greater sensitivity, enabling subcellular resolution and efficient tissue penetration in near-infrared imaging. 6FGA presents practicality and cost-effectiveness, making it a promising tool for nonradioactive, microplate-based assays at investigating SGLT-mediated glucose transport mechanisms.
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Affiliation(s)
- Richard S Agnes
- Department of Radiology, University Hospitals of Cleveland and Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA.
| | - Bryan J Traughber
- Department of Radiation Oncology, Mayo Clinic, Rochester, MN 55905, USA.
| | - Raymond F Muzic
- Department of Radiology, University Hospitals of Cleveland and Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA.
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Campbell E, Jordan C, Gilmour R. Fluorinated carbohydrates for 18F-positron emission tomography (PET). Chem Soc Rev 2023; 52:3599-3626. [PMID: 37171037 PMCID: PMC10243284 DOI: 10.1039/d3cs00037k] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Indexed: 05/13/2023]
Abstract
Carbohydrate diversity is foundational in the molecular literacy that regulates cellular function and communication. Consequently, delineating and leveraging this structure-function interplay continues to be a core research objective in the development of candidates for biomedical diagnostics. A totemic example is the ubiquity of 2-deoxy-2-[18F]-fluoro-D-glucose (2-[18F]-FDG) as a radiotracer for positron emission tomography (PET), in which metabolic trapping is harnessed. Building on this clinical success, more complex sugars with unique selectivities are gaining momentum in molecular recognition and personalised medicine: this reflects the opportunities that carbohydrate-specific targeting affords in a broader sense. In this Tutorial Review, key milestones in the development of 2-[18F]-FDG and related glycan-based radiotracers for PET are described, with their diagnostic functions, to assist in navigating this rapidly expanding field of interdisciplinary research.
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Affiliation(s)
- Emma Campbell
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster Corrensstraße 36, 48149, Münster, Germany.
- Cells in Motion Interfaculty Centre, Westfälische Wilhelms-Universität Münster, Röntgenstraße 16, 48149, Münster, Germany
| | - Christina Jordan
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster Corrensstraße 36, 48149, Münster, Germany.
- Cells in Motion Interfaculty Centre, Westfälische Wilhelms-Universität Münster, Röntgenstraße 16, 48149, Münster, Germany
| | - Ryan Gilmour
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster Corrensstraße 36, 48149, Münster, Germany.
- Cells in Motion Interfaculty Centre, Westfälische Wilhelms-Universität Münster, Röntgenstraße 16, 48149, Münster, Germany
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Zhang X, Basuli F, Shi ZD, Shah S, Shi J, Mitchell A, Lai J, Wang Z, Hammoud DA, Swenson RE. Synthesis and Evaluation of Fluorine-18-Labeled L-Rhamnose Derivatives. Molecules 2023; 28:molecules28093773. [PMID: 37175182 PMCID: PMC10180268 DOI: 10.3390/molecules28093773] [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: 03/03/2023] [Revised: 04/04/2023] [Accepted: 04/21/2023] [Indexed: 05/15/2023] Open
Abstract
The use of radiolabeled glucose for PET imaging resulted in the most commonly used tracer in the clinic, 2-deoxy-2-[18F]fluoroglucose (FDG). More recently, other radiolabeled sugars have been reported for various applications, including imaging tumors and infections. Therefore, in this study, we developed a series of fluorine-18-labeled L-rhamnose derivatives as potential PET tracers of various fungal and bacterial strains. Acetyl-protected triflate precursors of rhamnose were prepared and radiolabeled with fluorine-18 followed by hydrolysis to produce L-deoxy [18F]fluororhamnose. The overall radiochemical yield was 7-27% in a 90 min synthesis time with a radiochemical purity of 95%. In vivo biodistribution of the ligands using PET imaging showed that 2-deoxy-2-[18F]fluoro-L-rhamnose is stable for at least up to 60 min in mice and eliminated via renal clearance. The tracer also exhibited minimal tissue or skeletal uptake in healthy mice resulting in a low background signal.
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Affiliation(s)
- Xiang Zhang
- Chemistry and Synthesis Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Rockville, MD 20850, USA
| | - Falguni Basuli
- Chemistry and Synthesis Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Rockville, MD 20850, USA
| | - Zhen-Dan Shi
- Chemistry and Synthesis Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Rockville, MD 20850, USA
| | - Swati Shah
- Center for Infectious Disease Imaging, Radiology and Imaging Sciences, Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jianfeng Shi
- Chemistry and Synthesis Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Rockville, MD 20850, USA
| | - Amelia Mitchell
- Center for Infectious Disease Imaging, Radiology and Imaging Sciences, Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jianhao Lai
- Center for Infectious Disease Imaging, Radiology and Imaging Sciences, Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA
| | - Zeping Wang
- Center for Infectious Disease Imaging, Radiology and Imaging Sciences, Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA
| | - Dima A Hammoud
- Center for Infectious Disease Imaging, Radiology and Imaging Sciences, Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA
| | - Rolf E Swenson
- Chemistry and Synthesis Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Rockville, MD 20850, USA
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Rooijackers HMM, Wiegers EC, Tack CJ, van der Graaf M, de Galan BE. Brain glucose metabolism during hypoglycemia in type 1 diabetes: insights from functional and metabolic neuroimaging studies. Cell Mol Life Sci 2016; 73:705-22. [PMID: 26521082 PMCID: PMC4735263 DOI: 10.1007/s00018-015-2079-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 10/16/2015] [Accepted: 10/20/2015] [Indexed: 12/30/2022]
Abstract
Hypoglycemia is the most frequent complication of insulin therapy in patients with type 1 diabetes. Since the brain is reliant on circulating glucose as its main source of energy, hypoglycemia poses a threat for normal brain function. Paradoxically, although hypoglycemia commonly induces immediate decline in cognitive function, long-lasting changes in brain structure and cognitive function are uncommon in patients with type 1 diabetes. In fact, recurrent hypoglycemia initiates a process of habituation that suppresses hormonal responses to and impairs awareness of subsequent hypoglycemia, which has been attributed to adaptations in the brain. These observations sparked great scientific interest into the brain's handling of glucose during (recurrent) hypoglycemia. Various neuroimaging techniques have been employed to study brain (glucose) metabolism, including PET, fMRI, MRS and ASL. This review discusses what is currently known about cerebral metabolism during hypoglycemia, and how findings obtained by functional and metabolic neuroimaging techniques contributed to this knowledge.
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Affiliation(s)
- Hanne M M Rooijackers
- Department of Internal Medicine 463, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
| | - Evita C Wiegers
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Cees J Tack
- Department of Internal Medicine 463, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - Marinette van der Graaf
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Pediatrics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Bastiaan E de Galan
- Department of Internal Medicine 463, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
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Dexamethasone-induced insulin resistance: kinetic modeling using novel PET radiopharmaceutical 6-deoxy-6-[(18)F]fluoro-D-glucose. Mol Imaging Biol 2015; 16:710-20. [PMID: 24819311 DOI: 10.1007/s11307-014-0737-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
PURPOSE An insulin-resistant rat model, induced by dexamethasone, was used to evaluate a Michaelis-Menten-based kinetic model using 6-deoxy-6-[(18)F]fluoro-D-glucose (6-[(18)F]FDG) to quantify glucose transport with PET. PROCEDURES Seventeen, male, Sprague-Dawley rats were studied in three groups: control (Ctrl), control + insulin (Ctrl + I), and dexamethasone + insulin (Dex + I). PET scans were acquired for 2 h under euglycemic conditions in the Ctrl group and under hyperinsulinemic-euglycemic conditions in the Ctrl + I and Dex + I groups. RESULTS Glucose transport, assessed according to the 6-[(18)F]FDG concentration, was highest in skeletal muscle in the Ctrl + I, intermediate in the Dex + I, and lowest in the Ctrl group, while that in the brain was similar among the groups. Modeling analysis applied to the skeletal muscle uptake curves yielded values of parameters related to glucose transport that were greatest in the Ctrl + I group and increased to a lesser degree in the Dex + I group, compared to the Ctrl group. CONCLUSION 6-[(18)F]FDG and the Michaelis-Menten-based model can be used to measure insulin-stimulated glucose transport under basal and an insulin resistant state in vivo.
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Muzic RF, Chandramouli V, Huang HM, Wu C, Hatami A, Ismail-Beigi F. Human radiation dosimetry of 6-[18F]FDG predicted from preclinical studies. Med Phys 2014; 41:031910. [PMID: 24593728 DOI: 10.1118/1.4866217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The authors are developing 6-[(18)F]fluoro-6-deoxy-D-glucose (6-[(18)F]FDG) as an in vivo tracer of glucose transport. While 6-[(18)F]FDG has the same radionuclide half-life as 2-[(18)F]fluoro-2-deoxy-D-glucose (2-[(18)F]FDG) which is ubiquitously used for PET imaging, 6-[(18)F]FDG has special biologic properties and different biodistributions that make it preferable to 2-[(18)F]FDG for assessing glucose transport. In preparation for 6-[(18)F]FDG use in human PET scanning, the authors would like to determine the amount of 6-[(18)F]FDG to inject while maintaining radiation doses in a safe range. METHODS Rats were injected with 6-[(18)F]FDG, euthanized at specified times, and tissues were collected and assayed for activity content. For each tissue sample, the percent of injected dose per gram was calculated and extrapolated to that for humans in order to construct predicted time-courses. Residence times were calculated as areas under the curves and were used as inputs to OLINDA/EXM in order to calculate the radiation doses. RESULTS Unlike with 2-[(18)F]FDG for which the urinary bladder wall receives the highest absorbed dose due to urinary excretion, with 6-[(18)F]FDG there is little urinary excretion and osteogenic cells and the liver are predicted to receive the highest absorbed doses: 0.027 mGy/MBq (0.100 rad/mCi) and 0.018 mGy/MBq (0.066 rad/mCi), respectively. Also, the effective dose from 6-[(18)F]FDG, i.e., 0.013 mSv/MBq (0.046 rem/mCi), is predicted to be approximately 30% lower than that from 2-[(18)F]FDG. CONCLUSIONS 6-[(18)F]FDG will be safe for use in the PET scanning of humans.
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Affiliation(s)
- Raymond F Muzic
- Department of Radiology, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio 44106; Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106; and Case Center for Imaging Research, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio 44106
| | - Visvanathan Chandramouli
- Department of Radiology, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio 44106
| | - Hsuan-Ming Huang
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106 and Case Center for Imaging Research, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio 44106
| | - Chunying Wu
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106 and Case Center for Imaging Research, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio 44106
| | - Ahmad Hatami
- Department of Radiology, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio 44106
| | - Faramarz Ismail-Beigi
- Department of Medicine, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio 44106
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Huang HM, Chandramouli V, Ismail-Beigi F, Muzic RF. Hyperglycemia-induced stimulation of glucose transport in skeletal muscle measured by PET-[18F]6FDG and [18F]2FDG. Physiol Meas 2012; 33:1661-73. [PMID: 22986442 DOI: 10.1088/0967-3334/33/10/1661] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A physiologically based model proposed by our group has been developed to assess glucose transport and phosphorylation in skeletal muscle. In this study, we investigated whether our model has the ability to detect a glucose-induced increase in glucose transport in skeletal muscle. In particular, we used small-animal positron emission tomography (PET) data obtained from [18F]6-fluoro-6-deoxy-D-glucose ([18F]6FDG). A 2 h PET scan was acquired following a bolus injection of [18F]6FDG in rats currently under euglycemic or hyperglycemic conditions, while somatostatin was infused during both conditions in order to prevent a rise in the endogenous plasma insulin concentration. We were thus able to assess the effect of hyperglycemia per se. For a comparison of radiopharmaceuticals, additional rats were studied under the same conditions, using [18F]2-fluoro-2-deoxy-D-glucose ([18F]2FDG). When [18F]6FDG was used, the time-activity curves (TACs) for skeletal muscle had distinctly different shapes during euglycemic and hyperglycemic conditions. This was not the case with [18F]2FDG. For both [18F]6FDG and [18F]2FDG, the model detects increases in both interstitial and intracellular glucose concentrations, increases in the maximal velocity of glucose transport and increases in the rate of glucose transport, all in response to hyperglycemia. In contrast, there was no increase in the maximum velocity of glucose phosphorylation or in the glucose phosphorylation rate. Our model-based analyses of the PET data, obtained with either [18F]6FDG or [18F]2FDG, detect physiological changes consistent with established behavior. Moreover, based on differences in the TAC shapes, [18F]6FDG appears to be superior to [18F]2FDG for evaluating the effect of hyperglycemia on glucose metabolism in skeletal muscle.
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Affiliation(s)
- Hsuan-Ming Huang
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
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Wuest M, Kumar P, Wang M, Yang J, Jans HS, Wiebe LI. In vitro and in vivo evaluation of [(18)F]F-GAZ, a novel oxygen-mimetic azomycin-glucose conjugate, for imaging hypoxic tumor. Cancer Biother Radiopharm 2012; 27:473-80. [PMID: 22746267 DOI: 10.1089/cbr.2011.1148] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Several F-18-labeled 2-nitroimidazole (azomycin) derivatives have been proposed for imaging hypoxia using positron emission tomography (PET). Their cell penetration is based on passive diffusion, which limits their intracellular concentration maxima. The purpose of this study was to investigate the uptake of N-(2-[(18)F]fluoro-3-(6-O-glucosyl)propyl-azomycin ([(18)F]F-GAZ), a new azomycin-glucose conjugate, in vitro and in vivo. [(18)F]F-GAZ was synthesized from its tetraacetyl nosylate precursor by nucleophilic radiofluorination. [(18)F]F-GAZ was evaluated in vivo in EMT-6 tumor-bearing Balb/C mice utilizing the PET and biodistribution analysis. In vitro uptake of [(18)F]FDG by EMT-6 cells was measured in the presence of unlabeled F-GAZ, 2-FDG, and D-glucose. [(18)F]F-GAZ was rapidly cleared from all tissues, including the blood pool and kidneys, with ultimate accumulation in the urinary bladder. Uptake of tracer doses of [(18)F]F-GAZ into EMT-6 tumors was fast, reaching a standardized uptake value of 0.66±0.05 within 5-6 minutes postinjection (p.i.), and decreased to 0.24±0.04 by 60 minutes p.i. (n=6). A tumor-muscle ratio of 1.87±0.18 was observed after 60 minutes. Total uptake of [(18)F]F-GAZ in tumors (60 minutes) amounted to 1.25%±0.15% ID/g versus 0.61%±0.14% ID/g (n=4) in muscle. Similar biodistribution and excretion were observed using carrier-added (100 mg/kg) doses of F-GAZ. In vitro, D-glucose and unlabeled 2-FDG were two orders of magnitude more potent than F-GAZ as competitive inhibitors of [(18)F]FDG uptake into EMT-6 cells. Besides its interaction with glucose transporters, F-GAZ seems to be not transported in the presence of glucose. Furthermore, [(18)F]F-GAZ is unlikely to be effective as a hypoxia imaging agent. The low in vivo toxicity and substantial retention in tumor observed at high doses of F-GAZ do provide rationale for further testing as a radiosensitizer for external beam radiation therapy of radioresistant, hypoxic tumors.
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Affiliation(s)
- Melinda Wuest
- Department of Oncology, University of Alberta , and Cross Cancer Institute, Edmonton, Alberta, Canada
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Fernandes AB, Patarrão RS, Videira PA, Macedo MP. Understanding postprandial glucose clearance by peripheral organs: the role of the hepatic parasympathetic system. J Neuroendocrinol 2011; 23:1288-95. [PMID: 21933289 DOI: 10.1111/j.1365-2826.2011.02226.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The hepatic parasympathetic system is one of the major contributors for preserving insulin sensitivity in the postprandial state. Postprandial hepatic vagal control of whole-body glucose clearance and its effect on specific organs remains unknown. Our hypothesis is that, in the postprandial state, the hepatic parasympathetic nerves (HPN) are responsible for a considerable part of extra-hepatic tissue glucose clearance. Two groups of 9-week-old Sprague-Dawley rats were studied, comparing sham-operated versus hepatic parasympathetic denervated animals. Insulin sensitivity was evaluated in the postprandial state by the rapid insulin sensitivity test (RIST). [(3) H]2-deoxy-d-glucose was administered during the RIST. Plasma glucose rate of the disappearance and clearance by skeletal muscle, adipose tissue, liver, pancreas, heart and kidney of this radioisotope was measured. The postprandial denervated group showed a decrease insulin sensitivity of 41.4 ± 5.2%. This group of animals showed a decrease in the rate of plasma [(3) H]2-deoxy-d-glucose disappearance and skeletal muscle, heart and kidney glucose clearance by 45%, 35% and 67%, respectively. These studies show that the major contributor of postprandial whole-body glucose clearance was skeletal muscle; in the range 69-38%, depending on HPN integrity. The results obtained in the present study indicate that HPN are crucial for postprandial action of insulin through a mechanism that is essential for maintenance of skeletal muscle, heart and kidney glucose clearance. These results suggest that hepatic parasympathetic dysfunction could lie at the genesis of type 2 diabetes complications, namely insulin resistance, nephropathy and cardiomyopathy.
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Affiliation(s)
- A B Fernandes
- CEDOC, Faculdade de Ciências Médicas, FCM, Universidade Nova de Lisboa, Lisboa, Portugal
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Huang HM, Ismail-Beigi F, Muzic RF. A new Michaelis-Menten-based kinetic model for transport and phosphorylation of glucose and its analogs in skeletal muscle. Med Phys 2011; 38:4587-99. [PMID: 21928632 DOI: 10.1118/1.3599034] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE A new model is introduced that individually resolves the delivery, transport, and phosphorylation steps of metabolism of glucose and its analogs in skeletal muscle by interpreting dynamic positron emission tomography (PET) data. METHODS The model uniquely utilizes information obtained from the competition between glucose and its radiolabeled analogs. Importantly, the model avoids use of a lumped constant which may depend on physiological state. Four basic physiologic quantities constitute our model parameters, including the fraction of total tissue space occupied by interstitial space (f(IS)), a flow-extraction product and interstitial (IS(g)) and intracellular (IC(g)) glucose concentrations. Using the values of these parameters, cellular influx (CI) and efflux (CE) of glucose, glucose phosphorylation rate (PR), and maximal transport (V(G)) and phosphorylation capacities (V(H)) can all be determined. Herein, the theoretical derivation of our model is addressed and characterizes its properties via simulation. Specifically, the model performance is evaluated by simulation of basal and euglycemic hyperinsulinemic (EH) conditions. RESULTS In fitting the model-generated, synthetic data (including noise), mean estimates of all but IC(g) of the parameter values are within 5% of their values for both conditions. In addition, mean errors of CI, PR, and V(G) are less than 5% whereas those of VH and CE are not. CONCLUSIONS It is concluded that under the conditions tested, the novel model can provide accurate parameter estimates and physiological quantities, except IC(g) and two quantities that are dependent on IC(g), namely CE and VH. However, the ability to estimate IC(g) seems to improve with increases in intracellular glucose concentrations as evidenced by comparing IC(g) estimates under basal vs EH conditions.
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Affiliation(s)
- Hsuan-Ming Huang
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106, USA
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Muzic RF, Chandramouli V, Huang HM, Wu C, Wang Y, Ismail-Beigi F. Analysis of metabolism of 6FDG: a PET glucose transport tracer. Nucl Med Biol 2011; 38:667-74. [PMID: 21718942 DOI: 10.1016/j.nucmedbio.2010.12.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Revised: 11/04/2010] [Accepted: 12/08/2010] [Indexed: 11/26/2022]
Abstract
INTRODUCTION We are developing (18)F-labeled 6-fluoro-6-deoxy-D-glucose ([(18)F]6FDG) as a tracer of glucose transport. As part of this process it is important to characterize and quantify putative metabolites. In contrast to the ubiquitous positron emission tomography (PET) tracer (18)F-labeled 2-fluoro-2-deoxy-D-glucose ([(18)F]2FDG) which is phosphorylated and trapped intracellularly, the substitution of fluorine for a hydroxyl group at carbon-6 in [(18)F]6FDG should prevent its phosphorylation. Consequently, [(18)F]6FDG has the potential to trace the transport step of glucose metabolism without the confounding effects of phosphorylation and subsequent steps of metabolism. Herein the focus is to determine whether, and the degree to which, [(18)F]6FDG remains unchanged following intravenous injection. METHODS Biodistribution studies were performed using 6FDG labeled with (18)F or with the longer-lived radionuclides (3)H and (14)C. Tissues were harvested at 1, 6, and 24 h following intravenous administration and radioactivity was extracted from the tissues and analyzed using a combination of ion exchange columns, high-performance liquid chromatography, and chemical reactivity. RESULTS At the 1 h time-point, the vast majority of radioactivity in the liver, brain, heart, skeletal muscle, and blood was identified as 6FDG. At the 6-h and 24-h time points, there was evidence of a minor amount of radioactive material that appeared to be 6-fluoro-6-deoxy-D-sorbitol and possibly 6-fluoro-6-deoxy-D-gluconic acid. CONCLUSION On the time scale typical of PET imaging studies radioactive metabolites of [(18)F]6FDG are negligible.
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Affiliation(s)
- Raymond F Muzic
- Department of Radiology, Case Western Reserve University, Cleveland, OH 44106, USA.
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Kunos CA, Debernardo R, Fabien J, Dobbins DC, Zhang Y, Brindle J, Faulhaber PF. 18FDG-PET/CT Definition of Clinical Target Volume for Robotic Stereotactic Body Radiosurgery Treatment of Metastatic Gynecologic Malignancies. ACTA ACUST UNITED AC 2011; Suppl 4. [PMID: 25506042 DOI: 10.4172/2155-9619.s4-001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The objective of the current article was to evaluate 2-[18F]fluoro-2-deoxy-D-glucose 18F-FDG) as measured by positron emission tomography for delineation of abdominopelvic gross tumor volumes (GTV) for stereotactic body radiosurgery treatment (SBRT) of metastatic gynecologic cancers. A retrospective review of SBRT was conducted in 27 women with stage IV gynecologic cancers recurring in para-aortic lymph nodes. Robotic SBRT involved 2400 cGy in 3 consecutive 800 cGy daily fractions prescribed to a 3.0 mm expanded planning tumor volume (PTV) defined by both CT-based and 18F-FDG-based GTVs. In this study, 18F-FDG-based GTVs led to significantly larger PTVs in all 27 women, than if they had been based on CT GTVs alone (P < 0.001). Enlarged PTVs may have resulted from the breathing-induced target motion during the time of 18F-FDG image acquisition smearing 18F-FDG signal over a greater anatomic dimension. Ultimately, SBRT-target local control, based on the RECIST 1.1 criteria, was 96% (26 of 27), and associated with minor reversible toxicity. The use of 18F-FDG to define SBRT target volumes warrants further interrogation in SBRT clinical trials.
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Affiliation(s)
- Charles A Kunos
- Departments of Radiation Oncology, University Hospitals Case Medical Center and Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA
| | - Robert Debernardo
- Obstetrics and Gynecology Division of Gynecologic Oncology, University Hospitals Case Medical Center and Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA
| | - Jeffrey Fabien
- Departments of Radiation Oncology, University Hospitals Case Medical Center and Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA
| | - Donald C Dobbins
- Departments of Radiation Oncology, University Hospitals Case Medical Center and Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA
| | - Yuxia Zhang
- Departments of Radiation Oncology, University Hospitals Case Medical Center and Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA
| | - James Brindle
- Departments of Radiation Oncology, University Hospitals Case Medical Center and Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA
| | - Peter F Faulhaber
- Radiology Division of Nuclear Medicine, University Hospitals Case Medical Center and Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA
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Christopher BA, Huang HM, Berthiaume JM, McElfresh TA, Chen X, Croniger CM, Muzic RF, Chandler MP. Myocardial insulin resistance induced by high fat feeding in heart failure is associated with preserved contractile function. Am J Physiol Heart Circ Physiol 2010; 299:H1917-27. [PMID: 20852054 DOI: 10.1152/ajpheart.00687.2010] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Previous studies have reported that high fat feeding in mild to moderate heart failure (HF) results in the preservation of contractile function. Recent evidence has suggested that preventing the switch from fatty acid to glucose metabolism in HF may ameliorate dysfunction, and insulin resistance is one potential mechanism for regulating substrate utilization. This study was designed to determine whether peripheral and myocardial insulin resistance exists with HF and/or a high-fat diet and whether myocardial insulin signaling was altered accordingly. Rats underwent coronary artery ligation (HF) or sham surgery and were randomized to normal chow (NC; 14% kcal from fat) or a high-fat diet (SAT; 60% kcal from fat) for 8 wk. HF + SAT animals showed preserved systolic (+dP/dt and stroke work) and diastolic (-dP/dt and time constant of relaxation) function compared with HF + NC animals. Glucose tolerance tests revealed peripheral insulin resistance in sham + SAT, HF + NC, and HF + SAT animals compared with sham + NC animals. PET imaging confirmed myocardial insulin resistance only in HF + SAT animals, with an uptake ratio of 2.3 ± 0.3 versus 4.6 ± 0.7, 4.3 ± 0.4, and 4.2 ± 0.6 in sham + NC, sham + SAT, and HF + NC animals, respectively; the myocardial glucose utilization rate was similarly decreased in HF + SAT animals only. Western blot analysis of insulin signaling protein expression was indicative of cardiac insulin resistance in HF + SAT animals. Specifically, alterations in Akt and glycogen synthase kinase-3β protein expression in HF + SAT animals compared with HF + NC animals may be involved in mediating myocardial insulin resistance. In conclusion, HF animals fed a high-saturated fat exhibited preserved myocardial contractile function, peripheral and myocardial insulin resistance, decreased myocardial glucose utilization rates, and alterations in cardiac insulin signaling. These results suggest that myocardial insulin resistance may serve a cardioprotective function with high fat feeding in mild to moderate HF.
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Affiliation(s)
- Bridgette A Christopher
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio 44106-4970, USA
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