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Weidlinger S, Winterberger K, Pape J, Weidlinger M, Janka H, von Wolff M, Stute P. Impact of estrogens on resting energy expenditure: A systematic review. Obes Rev 2023; 24:e13605. [PMID: 37544655 DOI: 10.1111/obr.13605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 06/13/2023] [Accepted: 06/23/2023] [Indexed: 08/08/2023]
Abstract
The fear of weight gain is one of the main reasons for women not to initiate or to early discontinue hormonal contraception or menopausal hormone therapy. Resting energy expenditure is by far the largest component and the most important determinant of total energy expenditure. Given that low resting energy expenditure is a confirmed predictive factor for weight gain and consecutively for the development of obesity, research into the influence of sex steroids on resting energy expenditure is a particularly exciting area. The objective of this systematic review was to evaluate the effects of medication with natural and synthetic estrogens on resting energy expenditure in healthy normal weight and overweight women. Through complex systematic literature searches, a total of 10 studies were identified that investigated the effects of medication with estrogens on resting energy expenditure. Our results demonstrate that estrogen administration increases resting energy expenditure by up to +208 kcal per day in the context of contraception and by up to +222 kcal per day in the context of menopausal hormone therapy, suggesting a preventive effect of circulating estrogen levels and estrogen administration on weight gain and obesity development.
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Affiliation(s)
- Susanna Weidlinger
- Department of Obstetrics and Gynecology, University Hospital of Bern, Bern, Switzerland
| | - Katja Winterberger
- Department of Obstetrics and Gynecology, University Hospital of Bern, Bern, Switzerland
| | - Janna Pape
- Department of Obstetrics and Gynecology, University Hospital of Bern, Bern, Switzerland
| | | | - Heidrun Janka
- Medical Library, University Library Bern, University of Bern, Bern, Switzerland
| | - Michael von Wolff
- Department of Obstetrics and Gynecology, University Hospital of Bern, Bern, Switzerland
| | - Petra Stute
- Department of Obstetrics and Gynecology, University Hospital of Bern, Bern, Switzerland
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Xue S, Lee D, Berry DC. Thermogenic adipose tissue in energy regulation and metabolic health. Front Endocrinol (Lausanne) 2023; 14:1150059. [PMID: 37020585 PMCID: PMC10067564 DOI: 10.3389/fendo.2023.1150059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 03/07/2023] [Indexed: 04/07/2023] Open
Abstract
The ability to generate thermogenic fat could be a targeted therapy to thwart obesity and improve metabolic health. Brown and beige adipocytes are two types of thermogenic fat cells that regulate energy balance. Both adipocytes share common morphological, biochemical, and thermogenic properties. Yet, recent evidence suggests unique features exist between brown and beige adipocytes, such as their cellular origin and thermogenic regulatory processes. Beige adipocytes also appear highly plastic, responding to environmental stimuli and interconverting between beige and white adipocyte states. Additionally, beige adipocytes appear to be metabolically heterogenic and have substrate specificity. Nevertheless, obese and aged individuals cannot develop beige adipocytes in response to thermogenic fat-inducers, creating a key clinical hurdle to their therapeutic promise. Thus, elucidating the underlying developmental, molecular, and functional mechanisms that govern thermogenic fat cells will improve our understanding of systemic energy regulation and strive for new targeted therapies to generate thermogenic fat. This review will examine the recent advances in thermogenic fat biogenesis, molecular regulation, and the potential mechanisms for their failure.
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Affiliation(s)
| | | | - Daniel C. Berry
- Division of Nutritional Sciences, Cornell University, Ithaca, NY, United States
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Bogoni M, Cerci JJ, Cornelis FH, Nanni C, Tabacchi E, SchÖder H, Shyn PB, Sofocleous CT, Solomon SB, Kirov AS. Practice and prospects for PET/CT guided interventions. THE QUARTERLY JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING : OFFICIAL PUBLICATION OF THE ITALIAN ASSOCIATION OF NUCLEAR MEDICINE (AIMN) [AND] THE INTERNATIONAL ASSOCIATION OF RADIOPHARMACOLOGY (IAR), [AND] SECTION OF THE SOCIETY OF... 2021; 65:20-31. [PMID: 33494585 PMCID: PMC10446123 DOI: 10.23736/s1824-4785.21.03291-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
During the past 10 years, performing real-time molecular imaging with positron emission tomography (PET) in combination with computed tomography (CT) during interventional procedures has undergone rapid development. Keeping in mind the interest of the nuclear medicine readers, an update is provided of the current workflows using real-time PET/CT in percutaneous biopsies and tumor ablations. The clinical utility of PET/CT guided biopsies in cancer patients with lung, liver, lymphoma, and bone tumors are reviewed. Several technological developments, including the introduction of new PET tracers and robotic arms as well as opportunities provided through acquiring radioactive biopsy specimens are briefly reviewed.
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Affiliation(s)
| | | | | | - Cristina Nanni
- Unit of Nuclear Medicine, S. Orsola-Malpighi Hospital, Bologna, Italy
| | - Elena Tabacchi
- Unit of Nuclear Medicine, S. Orsola-Malpighi Hospital, Bologna, Italy
| | - Heiko SchÖder
- Unit of Nuclear Medicine, Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Paul B Shyn
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Constantinos T Sofocleous
- Unit of Interventional Radiology, Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Stephen B Solomon
- Unit of Interventional Radiology, Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Assen S Kirov
- Unit of Molecular Imaging and Therapy Physics, Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, USA -
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Santhanam P, Rowe SP, Solnes LB, Quainoo B, Ahima RS. A systematic review of imaging studies of human brown adipose tissue. Ann N Y Acad Sci 2021; 1495:5-23. [PMID: 33604891 DOI: 10.1111/nyas.14579] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 01/25/2021] [Accepted: 01/31/2021] [Indexed: 02/06/2023]
Abstract
Brown adipose tissue (BAT) is involved in energy dissipation and has been linked to weight loss, insulin sensitivity, and reduced risk of atherosclerotic disease. BAT is found most often in the supraclavicular region, as well as mediastinal and paravertebral areas, and it is predominantly seen in young persons. BAT is activated by cold temperature and the sympathetic nervous system. In humans, BAT was initially detected via 2-deoxy-2-[18 F]fluoro-d-glucose (FDG) positron emission tomography/computed tomography (PET/CT), a high-resolution molecular imaging modality used to identify and stage malignancies. Recent studies have shown that BAT can be localized using conventional imaging modalities, such as CT or magnetic resonance imaging, as well as radiotracers used for single-photon emission CT. In this systematic review, we have summarized the evidence for BAT detection in humans using various imaging techniques.
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Affiliation(s)
- Prasanna Santhanam
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Johns Hopkins University School of Medicine, Asthma and Allergy Center, Baltimore, Maryland
| | - Steven P Rowe
- Division of Nuclear Medicine, Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Lilja B Solnes
- Division of Nuclear Medicine, Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Brittany Quainoo
- Columbian College of Arts and Sciences, George Washington University, Washington, DC
| | - Rexford S Ahima
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Johns Hopkins University School of Medicine, Asthma and Allergy Center, Baltimore, Maryland
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Brown Adipose Tissue and Its Role in Insulin and Glucose Homeostasis. Int J Mol Sci 2021; 22:ijms22041530. [PMID: 33546400 PMCID: PMC7913527 DOI: 10.3390/ijms22041530] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 01/21/2021] [Accepted: 02/01/2021] [Indexed: 12/15/2022] Open
Abstract
The increased worldwide prevalence of obesity, insulin resistance, and their related metabolic complications have prompted the scientific world to search for new possibilities to combat obesity. Brown adipose tissue (BAT), due to its unique protein uncoupling protein 1 (UPC1) in the inner membrane of the mitochondria, has been acknowledged as a promising approach to increase energy expenditure. Activated brown adipocytes dissipate energy, resulting in heat production. In other words, BAT burns fat and increases the metabolic rate, promoting a negative energy balance. Moreover, BAT alleviates metabolic complications like dyslipidemia, impaired insulin secretion, and insulin resistance in type 2 diabetes. The aim of this review is to explore the role of BAT in total energy expenditure, as well as lipid and glucose homeostasis, and to discuss new possible activators of brown adipose tissue in humans to treat obesity and metabolic disorders.
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Tupone D, Cetas JS. In a model of SAH-induced neurogenic fever, BAT thermogenesis is mediated by erythrocytes and blocked by agonism of adenosine A1 receptors. Sci Rep 2021; 11:2752. [PMID: 33531584 PMCID: PMC7854628 DOI: 10.1038/s41598-021-82407-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 01/20/2021] [Indexed: 11/09/2022] Open
Abstract
Neurogenic fever (NF) after subarachnoid hemorrhage (SAH) is a major cause of morbidity that is associated with poor outcomes and prolonged stay in the neurointensive care unit (NICU). Though SAH is a much more common cause of fever than sepsis in the NICU, it is often a diagnosis of exclusion, requiring significant effort to rule out an infectious source. NF does not respond to standard anti-pyretic medications such as COX inhibitors, and lack of good medical therapy has led to the introduction of external cooling systems that have their own associated problems. In a rodent model of SAH, we measured the effects of injecting whole blood, blood plasma, or erythrocytes on the sympathetic nerve activity to brown adipose tissue and on febrile thermogenesis. We demonstrate that following SAH the acute activation of brown adipose tissue leading to NF, is not dependent on PGE2, that subarachnoid space injection of whole blood or erythrocytes, but not plasma alone, is sufficient to trigger brown adipose tissue thermogenesis, and that activation of adenosine A1 receptors in the CNS can block the brown adipose tissue thermogenic component contributing to NF after SAH. These findings point to a distinct thermogenic mechanism for generating NF, compared to those due to infectious causes, and will hopefully lead to new therapies.
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Affiliation(s)
- Domenico Tupone
- Department of Biomedical and Neuromotor Science, University of Bologna, 40126, Bologna, Italy. .,Department of Neurological Surgery, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239-3098, USA.
| | - Justin S Cetas
- Department of Neurological Surgery, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239-3098, USA.,Portland VA Health Care System, Portland, OR, USA
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Cannon B, de Jong JMA, Fischer AW, Nedergaard J, Petrovic N. Human brown adipose tissue: Classical brown rather than brite/beige? Exp Physiol 2020; 105:1191-1200. [PMID: 32378255 DOI: 10.1113/ep087875] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Accepted: 05/04/2020] [Indexed: 12/13/2022]
Abstract
NEW FINDINGS What is the topic of this review? It has been suggested that human brown adipose tissue (BAT) is more similar to the brite/beige adipose tissue of mice than to classical BAT of mice. The basis of this is discussed in relationship to the physiological conditions of standard experimental mice. What advances does it highlight? We highlight that, provided mouse adipose tissues are examined under physiological conditions closer to those prevalent for most humans, the gene expression profile of mouse classical BAT is more similar to that of human BAT than is the profile of mouse brite/beige adipose tissue. Human BAT is therefore not different in nature from classical mouse BAT. ABSTRACT Since the presence of brown adipose tissue (BAT) was established in adult humans some 13 years ago, its physiological significance and molecular characteristics have been discussed. In particular, it has been proposed that the mouse adipose tissue depot most closely resembling and molecularly parallel to human BAT is not classical mouse BAT. Instead, so-called brite or beige adipose tissue, which is characteristically observed in the inguinal 'white' adipose tissue depot of mice, has been proposed to be the closest mouse equivalent of human BAT. We summarize here the published evidence examining this question. We emphasize the differences in tissue appearance and tissue transcriptomes from 'standard' mice [young, chow fed and, in effect semi-cold exposed (20°C)] versus 'physiologically humanized' mice [middle-aged, high-fat diet-fed mice living at thermoneutrality (30°C)]. We find that in the physiologically humanized mice, classical BAT displays molecular and cellular characteristics that are more akin to human BAT than are those of brite/beige adipose tissues from either standard or physiologically humanized mice. We suggest, therefore, that mouse BAT is the more relevant tissue for translational studies. This is an invited summary of a presentation given at Physiology 2019 (Aberdeen).
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Affiliation(s)
- Barbara Cannon
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Jasper M A de Jong
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Alexander W Fischer
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Jan Nedergaard
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Natasa Petrovic
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
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8
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Chondronikola M, Sidossis LS. Brown and beige fat: From molecules to physiology. Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1864:91-103. [DOI: 10.1016/j.bbalip.2018.05.014] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2017] [Revised: 02/11/2018] [Accepted: 05/23/2018] [Indexed: 12/16/2022]
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Law J, Chalmers J, Morris DE, Robinson L, Budge H, Symonds ME. The use of infrared thermography in the measurement and characterization of brown adipose tissue activation. Temperature (Austin) 2018; 5:147-161. [PMID: 30393752 DOI: 10.1080/23328940.2017.1397085] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 10/16/2017] [Accepted: 10/23/2017] [Indexed: 10/18/2022] Open
Abstract
Interest in brown adipose tissue has increased in recent years as a potential target for novel obesity, diabetes and metabolic disease treatments. One of the significant limitations to rapid progress has been the difficulty in measuring brown adipose tissue activity, especially in humans. Infrared thermography (IRT) is being increasingly recognized as a valid and complementary method to standard imaging modalities, such as positron emission tomography-computed tomography (PET/CT). In contrast to PET/CT, it is non-invasive, cheap and quick, allowing, for the first time, the possibility of large studies of brown adipose tissue (BAT) on healthy populations and children. Variations in study protocols and analysis methods currently limit direct comparison between studies but IRT following appropriate BAT stimulation consistently shows a change in supraclavicular skin temperature and a close association with results from BAT measurements from other methods.
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Affiliation(s)
- James Law
- Early Life Research Unit, Division of Child Health, Obstetrics & Gynaecology, School of Medicine, University of Nottingham, Nottingham, United Kingdom
| | - Jane Chalmers
- Nottingham Digestive Diseases Centre, University of Nottingham and National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust and University of Nottingham
| | - David E Morris
- Department of Electrical & Electronic Engineering, Faculty of Engineering, University of Nottingham, United Kingdom
| | - Lindsay Robinson
- Early Life Research Unit, Division of Child Health, Obstetrics & Gynaecology, School of Medicine, University of Nottingham, Nottingham, United Kingdom
| | - Helen Budge
- Early Life Research Unit, Division of Child Health, Obstetrics & Gynaecology, School of Medicine, University of Nottingham, Nottingham, United Kingdom
| | - Michael E Symonds
- Early Life Research Unit, Division of Child Health, Obstetrics & Gynaecology, School of Medicine, University of Nottingham, Nottingham, United Kingdom.,Nottingham Digestive Diseases Centre, University of Nottingham and National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust and University of Nottingham
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10
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Mitochondrial Uncoupler Prodrug of 2,4-Dinitrophenol, MP201, Prevents Neuronal Damage and Preserves Vision in Experimental Optic Neuritis. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2017; 2017:7180632. [PMID: 28680531 PMCID: PMC5478871 DOI: 10.1155/2017/7180632] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 04/30/2017] [Indexed: 11/18/2022]
Abstract
The ability of novel mitochondrial uncoupler prodrug of 2,4-dinitrophenol (DNP), MP201, to prevent neuronal damage and preserve visual function in an experimental autoimmune encephalomyelitis (EAE) model of optic neuritis was evaluated. Optic nerve inflammation, demyelination, and axonal loss are prominent features of optic neuritis, an inflammatory optic neuropathy often associated with the central nervous system demyelinating disease multiple sclerosis. Currently, optic neuritis is frequently treated with high-dose corticosteroids, but treatment fails to prevent permanent neuronal damage and associated vision changes that occur as optic neuritis resolves, thus suggesting that additional therapies are required. MP201 administered orally, once per day, attenuated visual dysfunction, preserved retinal ganglion cells (RGCs), and reduced RGC axonal loss and demyelination in the optic nerves of EAE mice, with limited effects on inflammation. The prominent mild mitochondrial uncoupling properties of MP201, with slow elimination of DNP, may contribute to the neuroprotective effect by modulating the entire mitochondria's physiology directly. Results suggest that MP201 is a potential novel treatment for optic neuritis.
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Evaluation of 99mTc-3PRGD 2 integrin receptor imaging in hepatocellular carcinoma tumour-bearing mice: comparison with 18F-FDG metabolic imaging. Ann Nucl Med 2017; 31:486-494. [PMID: 28474165 PMCID: PMC5486497 DOI: 10.1007/s12149-017-1173-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 04/17/2017] [Indexed: 01/15/2023]
Abstract
Objective Our study was designed to explore the utility of 99mTc-HYNIC-PEG4-E[PEG4-c(RGDfK)]2 (99mTc-3PRGD2) for the detection of hepatocellular carcinoma (HCC) and specifically to compare the diagnostic performance of 99mTc-3PRGD2 integrin receptor imaging and 2-18-fluoro-2-deoxy-d-glucose (18F-FDG) metabolic imaging in a nude mouse model. Methods 99mTc-3PRGD2 was synthesized using a HYNIC-3PRGD2 lyophilized kit with 99mTcO4 labelling. The nude mouse animal model was established by subcutaneously injecting 5 × 107/ml HepG2 cells into the shoulder flank of each mouse. Biodistribution studies were performed at 0.5, 1, 2 and 4 h after intravenous administration of 0.37 MBq of 99mTc-3PRGD2. Immunohistochemistry was performed to evaluate the expression level of integrin αvβ3 in the HCC tissues. Dynamic imaging was performed using list-mode after the administration of 55.5 MBq of 99mTc-3PRGD2, to reconstruct the multiphase images and acquire the best initial scan time. At 8, 12, 16, 20 and 24 days after inoculation with HepG2 cells, 55.5 MBq of 99mTc-3PRGD2 and 37 MBq of 18F-FDG were injected successively into the nude mouse model, subsequently, simultaneous SPECT/PET imaging was performed to calculate the tumour volume and tumour uptake of 99mTc-3PRGD2 and 18F-FDG. Results The biodistribution study first validated that the tumour uptake of 99mTc-3PRGD2 at the different time points was higher than that of all the other organs tested in the experiment, except for the kidney. Integrin αvβ3 expressed highly in early stage HCC and declined for further necrosis of the tumour tissue. Subcutaneous tumours were visualized clearly with excellent contrast under 99mTc-3PRGD2 SPECT/CT imaging, and the multiphase imaging comparison showed the tumours were prominent at 0.5 h, suggesting that the best initial scan time is 0.5 h post-injection. The comparison of the imaging results of the two methods showed that 99mTc-3PRGD2 integrin receptor imaging was more sensitive than 18F-FDG metabolic imaging for the detection of early stage HCC, meanwhile the tumour uptake of 99mTc-3PRGD2 was consistently higher than that of 18F-FDG. However, as tumour necrosis further increased in HCC tissues, the uptake of 18F-FDG was higher than that of 99mTc-3PRGD2. Conclusion Our study demonstrated that 99mTc-3PRGD2 is a valuable tumour molecular probe for the detection of early stage HCC compared with 18F-FDG, meriting further investigation of 99mTc-3PRGD2 as a novel SPECT tracer for tumour imaging.
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Cousins J, Czachowski M, Muthukrishnan A, Currie G. Pediatric Brown Adipose Tissue on 18F-FDG PET: Diazepam Intervention. J Nucl Med Technol 2017; 45:82-86. [DOI: 10.2967/jnmt.116.187385] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 01/31/2017] [Indexed: 11/16/2022] Open
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Parisi MT, Bermo MS, Alessio AM, Sharp SE, Gelfand MJ, Shulkin BL. Optimization of Pediatric PET/CT. Semin Nucl Med 2017; 47:258-274. [PMID: 28417855 DOI: 10.1053/j.semnuclmed.2017.01.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
PET/CT, the most common form of hybrid imaging, has transformed oncologic imaging and is increasingly being used for nononcologic applications as well. Performing PET/CT in children poses unique challenges. Not only are children more sensitive to the effects of radiation than adults but, following radiation exposure, children have a longer postexposure life expectancy in which to exhibit adverse radiation effects. Both the PET and CT components of the study contribute to the total patient radiation dose, which is one of the most important risks of the study in this population. Another risk in children, not typically encountered in adults, is potential neurotoxicity related to the frequent need for general anesthesia in this patient population. Optimizing pediatric PET/CT requires making improvements to both the PET and the CT components of the procedure while decreasing the potential for risk. This can be accomplished through judicious performance of imaging, the use of recommended pediatric 18fluorine-2-fluoro-2-deoxy-d-glucose (18F-FDG) administered activities, thoughtful selection of pediatric-specific CT imaging parameters, careful patient preparation, and use of appropriate patient immobilization. In this article, we will review a variety of strategies for radiation dose optimization in pediatric 18F-FDG-PET/CT focusing on these processes. Awareness of and careful selection of pediatric-specific CT imaging parameters designed for appropriate diagnostic, localization, or attenuation correction only CT, in conjunction with the use of recommended radiotracer administered activities, will help to ensure image quality while limiting patient radiation exposure. Patient preparation, an important determinant of image quality, is another focus of this review. Appropriate preparative measures are even more crucial in children in whom there is a higher incidence of brown fat, which can interfere with study interpretation. Finally, we will discuss measures to improve the patient experience, the resource use, the departmental workflow, and the diagnostic performance of the study through the use of appropriate technology, all in the context of minimizing procedure-related risks.
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Affiliation(s)
- Marguerite T Parisi
- Departments of Radiology, University of Washington School of Medicine, Seattle Children's Hospital, Seattle, WA; Departments of Pediatrics, University of Washington School of Medicine and Seattle Children's Hospital, Seattle, WA.
| | - Mohammed S Bermo
- Department of Nuclear Medicine, University of Washington School of Medicine, Seattle, WA
| | - Adam M Alessio
- Departments of Radiology, University of Washington School of Medicine, Seattle Children's Hospital, Seattle, WA
| | - Susan E Sharp
- Departments of Radiology, University of Cincinnati College of Medicine and Cincinnati Children's Hospital Medical Center, Cincinatti, OH
| | - Michael J Gelfand
- Departments of Radiology, University of Cincinnati College of Medicine and Cincinnati Children's Hospital Medical Center, Cincinatti, OH
| | - Barry L Shulkin
- Department of Diagnostic Imaging, St. Jude Children's Research Hospital, Memphis, TN
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Thuzar M, Ho KKY. MECHANISMS IN ENDOCRINOLOGY: Brown adipose tissue in humans: regulation and metabolic significance. Eur J Endocrinol 2016; 175:R11-25. [PMID: 27220620 DOI: 10.1530/eje-15-1217] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 02/09/2016] [Indexed: 01/14/2023]
Abstract
The recent discovery that functional brown adipose tissue (BAT) persists in adult humans has enkindled a renaissance in metabolic research, with a view of harnessing its thermogenic capacity to combat obesity. This review focuses on the advances in the regulation and the metabolic significance of BAT in humans. BAT activity in humans is stimulated by cold exposure and by several factors such as diet and metabolic hormones. BAT function is regulated at two levels: an acute process involving the stimulation of the intrinsic thermogenic activity of brown adipocytes and a chronic process of growth involving the proliferation of pre-existing brown adipocytes or differentiation to brown adipocytes of adipocytes from specific white adipose tissue depots. BAT activity is reduced in the obese, and its stimulation by cold exposure increases insulin sensitivity and reduces body fat. These observations provide strong evidence that BAT plays a significant role in energy balance in humans and has the potential to be harnessed as a therapeutic target for the management of obesity.
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Affiliation(s)
- Moe Thuzar
- Department of Endocrinology and DiabetesPrincess Alexandra Hospital, Brisbane, Queensland, AustraliaSchool of MedicineUniversity of Queensland, Brisbane, Queensland 4102, Australia Department of Endocrinology and DiabetesPrincess Alexandra Hospital, Brisbane, Queensland, AustraliaSchool of MedicineUniversity of Queensland, Brisbane, Queensland 4102, Australia
| | - Ken K Y Ho
- Department of Endocrinology and DiabetesPrincess Alexandra Hospital, Brisbane, Queensland, AustraliaSchool of MedicineUniversity of Queensland, Brisbane, Queensland 4102, Australia Department of Endocrinology and DiabetesPrincess Alexandra Hospital, Brisbane, Queensland, AustraliaSchool of MedicineUniversity of Queensland, Brisbane, Queensland 4102, Australia
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15
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Chakraborty D, Bhattacharya A, Mittal BR. Patterns of brown fat uptake of 18F-fluorodeoxyglucose in positron emission tomography/computed tomography scan. Indian J Nucl Med 2015; 30:320-2. [PMID: 26430315 PMCID: PMC4579616 DOI: 10.4103/0972-3919.164147] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Fluorodeoxyglucose (FDG) positron emission tomography (PET) has become the common imaging modality in oncological practice. FDG uptake is seen in brown adipose tissue in a significant number of patients. Recognizing the uptake patterns is important for optimal FDG PET interpretation. The introduction of PET/computed tomography (PET/CT) revolutionized PET imaging, bringing much-needed anatomical information. Careful review and correlation of FDG PET images with anatomical imaging should be performed to characterize accurately any lesion having high FDG uptake.
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Affiliation(s)
- Dhritiman Chakraborty
- Department of Nuclear and Experimental Medical Sciences, Institute of Post Graduate Medical Education and Research, Kolkata, West Bengal, India
| | - Anish Bhattacharya
- Department of Nuclear Medicine and PET, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Bhagwant Rai Mittal
- Department of Nuclear Medicine and PET, Postgraduate Institute of Medical Education and Research, Chandigarh, India
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16
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Kumar R, Mukherjee A, Mittal BR. Special Techniques in PET/Computed Tomography Imaging for Evaluation of Head and Neck Cancer. PET Clin 2015; 11:13-20. [PMID: 26590440 DOI: 10.1016/j.cpet.2015.07.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
PET with fluorodeoxyglucose F 18 (FDG)/computed tomography (CT) imaging has significantly improved the management of head and neck cancer. FDG, however, is not tumor-specific and various image interpretation pitfalls may occur because of false-positive and -negative causes of FDG uptake. Routine imaging examination of head and neck malignancies does not yield all of the necessary data, even with the most advanced imaging technique. Specific interventions, such as use of different dynamic maneuvers and pharmacologic interventions, may provide useful information about the lesion. This article reviews the use of special techniques in FDG PET/CT imaging and whole-body FDG PET/CT imaging for evaluation of head and neck cancer.
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Affiliation(s)
- Rakesh Kumar
- Diagnostic Nuclear Medicine Division, Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi 110029, India.
| | - Anirban Mukherjee
- Diagnostic Nuclear Medicine Division, Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi 110029, India
| | - Bhagwant Rai Mittal
- Department of Nuclear Medicine, Post Graduate Institute of Medical Education and Research, Chandigarh 160012, India
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Morrison SF, Madden CJ. Central nervous system regulation of brown adipose tissue. Compr Physiol 2015; 4:1677-713. [PMID: 25428857 DOI: 10.1002/cphy.c140013] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Thermogenesis, the production of heat energy, in brown adipose tissue is a significant component of the homeostatic repertoire to maintain body temperature during the challenge of low environmental temperature in many species from mouse to man and plays a key role in elevating body temperature during the febrile response to infection. The sympathetic neural outflow determining brown adipose tissue (BAT) thermogenesis is regulated by neural networks in the CNS which increase BAT sympathetic nerve activity in response to cutaneous and deep body thermoreceptor signals. Many behavioral states, including wakefulness, immunologic responses, and stress, are characterized by elevations in core body temperature to which central command-driven BAT activation makes a significant contribution. Since energy consumption during BAT thermogenesis involves oxidation of lipid and glucose fuel molecules, the CNS network driving cold-defensive and behavioral state-related BAT activation is strongly influenced by signals reflecting the short- and long-term availability of the fuel molecules essential for BAT metabolism and, in turn, the regulation of BAT thermogenesis in response to metabolic signals can contribute to energy balance, regulation of body adipose stores and glucose utilization. This review summarizes our understanding of the functional organization and neurochemical influences within the CNS networks that modulate the level of BAT sympathetic nerve activity to produce the thermoregulatory and metabolic alterations in BAT thermogenesis and BAT energy expenditure that contribute to overall energy homeostasis and the autonomic support of behavior.
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Affiliation(s)
- Shaun F Morrison
- Department of Neurological Surgery, Oregon Health & Science University, Portland, Oregon
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Sidossis L, Kajimura S. Brown and beige fat in humans: thermogenic adipocytes that control energy and glucose homeostasis. J Clin Invest 2015; 125:478-86. [PMID: 25642708 DOI: 10.1172/jci78362] [Citation(s) in RCA: 481] [Impact Index Per Article: 53.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Brown adipose tissue (BAT), a specialized fat that dissipates energy to produce heat, plays an important role in the regulation of energy balance. Two types of thermogenic adipocytes with distinct developmental and anatomical features exist in rodents and humans: classical brown adipocytes and beige (also referred to as brite) adipocytes. While classical brown adipocytes are located mainly in dedicated BAT depots of rodents and infants, beige adipocytes sporadically reside with white adipocytes and emerge in response to certain environmental cues, such as chronic cold exposure, a process often referred to as "browning" of white adipose tissue. Recent studies indicate the existence of beige adipocytes in adult humans, making this cell type an attractive therapeutic target for obesity and obesity-related diseases, including type 2 diabetes. This Review aims to cover recent progress in our understanding of the anatomical, developmental, and functional characteristics of brown and beige adipocytes and discuss emerging questions, with a special emphasis on adult human BAT.
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Dao CK, Nowinski SM, Mills EM. The heat is on: Molecular mechanisms of drug-induced hyperthermia. Temperature (Austin) 2014; 1:183-91. [PMID: 27626045 PMCID: PMC5008714 DOI: 10.4161/23328940.2014.985953] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 11/05/2014] [Accepted: 11/06/2014] [Indexed: 01/01/2023] Open
Abstract
Thermoregulation is an essential homeostatic process in which critical mechanisms of heat production and dissipation are controlled centrally in large part by the hypothalamus and peripherally by activation of the sympathetic nervous system. Drugs that disrupt the components of this highly orchestrated multi-organ process can lead to life-threatening hyperthermia. In most cases, hyperthermic agents raise body temperature by increasing the central and peripheral release of thermoregulatory neurotransmitters that ultimately lead to heat production in thermogenic effector organs skeletal muscle (SKM) and brown adipose tissue (BAT). In many cases hyperthermic drugs also decrease heat dissipation through peripheral changes in blood flow. Drug-induced heat production is driven by the stimulation of mechanisms that normally regulate the adaptive thermogenic responses including both shivering and non-shivering thermogenesis (NST) mechanisms. Modulation of the mitochondrial electrochemical proton/pH gradient by uncoupling protein 1 (UCP1) in BAT is the most well characterized mechanism of NST in response to cold, and may contribute to thermogenesis induced by sympathomimetic agents, but this is far from established. However, the UCP1 homologue, UCP3, and the ryanodine receptor (RYR1) are established mediators of toxicant-induced hyperthermia in SKM. Defining the molecular mechanisms that orchestrate drug-induced hyperthermia will be essential in developing treatment modalities for thermogenic illnesses. This review will briefly summarize mechanisms of thermoregulation and provide a survey of pharmacologic agents that can lead to hyperthermia. We will also provide an overview of the established and candidate molecular mechanisms that regulate the actual thermogenic processes in heat effector organs BAT and SKM.
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Affiliation(s)
- Christine K Dao
- Division of Pharmacology and Toxicology; College of Pharmacy; The University of Texas at Austin ; Austin, TX USA
| | - Sara M Nowinski
- Department of Biochemistry; University of Utah School of Medicine ; Salt Lake City, UT USA
| | - Edward M Mills
- Division of Pharmacology and Toxicology; College of Pharmacy; The University of Texas at Austin ; Austin, TX USA
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Tupone D, Madden CJ, Morrison SF. Autonomic regulation of brown adipose tissue thermogenesis in health and disease: potential clinical applications for altering BAT thermogenesis. Front Neurosci 2014; 8:14. [PMID: 24570653 PMCID: PMC3916784 DOI: 10.3389/fnins.2014.00014] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Accepted: 01/20/2014] [Indexed: 01/04/2023] Open
Abstract
From mouse to man, brown adipose tissue (BAT) is a significant source of thermogenesis contributing to the maintenance of the body temperature homeostasis during the challenge of low environmental temperature. In rodents, BAT thermogenesis also contributes to the febrile increase in core temperature during the immune response. BAT sympathetic nerve activity controlling BAT thermogenesis is regulated by CNS neural networks which respond reflexively to thermal afferent signals from cutaneous and body core thermoreceptors, as well as to alterations in the discharge of central neurons with intrinsic thermosensitivity. Superimposed on the core thermoregulatory circuit for the activation of BAT thermogenesis, is the permissive, modulatory influence of central neural networks controlling metabolic aspects of energy homeostasis. The recent confirmation of the presence of BAT in human and its function as an energy consuming organ have stimulated interest in the potential for the pharmacological activation of BAT to reduce adiposity in the obese. In contrast, the inhibition of BAT thermogenesis could facilitate the induction of therapeutic hypothermia for fever reduction or to improve outcomes in stroke or cardiac ischemia by reducing infarct size through a lowering of metabolic oxygen demand. This review summarizes the central circuits for the autonomic control of BAT thermogenesis and highlights the potential clinical relevance of the pharmacological inhibition or activation of BAT thermogenesis.
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Affiliation(s)
- Domenico Tupone
- Department of Neurological Surgery, Oregon Health and Science University Portland, OR, USA
| | - Christopher J Madden
- Department of Neurological Surgery, Oregon Health and Science University Portland, OR, USA
| | - Shaun F Morrison
- Department of Neurological Surgery, Oregon Health and Science University Portland, OR, USA
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Abstract
Brown adipose tissue (BAT) plays a key role in energy homeostasis and thermogenesis in animals, conferring protection against diet-induced obesity and hypothermia through the action of uncoupling protein 1 (UCP1). Recent metabolic imaging studies using positron emission tomography computerized tomography (PET-CT) scanning have serendipitously revealed significant depots of BAT in the cervical-supraclavicular regions, demonstrating persistence of BAT beyond infancy. Subsequent cold-stimulated PET-CT studies and direct histological examination of adipose tissues have demonstrated that BAT is highly prevalent in adult humans. BAT activity correlates positively with increment of energy expenditure during cold exposure and negatively with age, body mass index, and fasting glycemia, suggesting regulatory links between BAT, cold-induced thermogenesis, and energy metabolism. Human BAT tissue biopsies express UCP1 and harbor inducible precursors that differentiate into UCP1-expressing adipocytes in vitro. These recent discoveries represent a metabolic renaissance for human adipose biology, overturning previous belief that BAT had no relevance in adult humans. They also have implications for the understanding of the pathogenesis and treatment of obesity and its metabolic sequelae.
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Affiliation(s)
- Paul Lee
- School of Medicine, University of Queensland, Brisbane, Queensland 4107, Australia.
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Miao Q, Zhao XL, Zhang QY, Zhang ZY, Guan YH, Ye HY, Zhang S, Zeng MF, Zuo CT, Li YM. Stability in brain glucose metabolism following brown adipose tissue inactivation in chinese adults. AJNR Am J Neuroradiol 2012; 33:1464-9. [PMID: 22576895 DOI: 10.3174/ajnr.a3006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE The thermogenesis of BAT is believed to be controlled through some pathways initiated in the brain, though the changes in brain activity among different states of BAT-positive subjects are still unclear. We hypothesized that some significant differences of regional cerebral metabolism between various groups were related to the BAT activities regardless of temperature changes. MATERIALS AND METHODS Relative regional cerebral glucose metabolism was compared between 15 healthy subjects with activated BAT and 30 healthy controls without activated BAT by using a brain FDG-PET scan. A follow-up PET scan was performed to assess metabolic changes of the brain when BAT activity was eliminated by heat exposure. RESULTS Compared with controls, BAT-positive subjects exhibited lower activity in the inferior parietal lobule, limbic system, and frontal lobe and higher activity in the precuneus before heat exposure. Compared with the BAT elimination status, subjects with activated BAT showed a decreased metabolism in the parietal lobe, frontal lobe, culmen, cingulate gyrus, and sublobar region. Compared with controls, BAT-positive subjects after BAT inactivation had significant hypometabolic areas in the temporal lobe and limbic lobe and hypermetabolic areas in the parietal lobe. CONCLUSIONS Our findings illustrate that changes of regional cerebral metabolism are related to BAT activities regardless of temperature changes. This before-after controlled study supports the finding that the brain responses appear to be active in modulating the metabolic function of BAT activity.
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Affiliation(s)
- Q Miao
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, China
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Gilsanz V, Smith ML, Goodarzian F, Kim M, Wren TAL, Hu HH. Changes in brown adipose tissue in boys and girls during childhood and puberty. J Pediatr 2012; 160:604-609.e1. [PMID: 22048045 PMCID: PMC3307823 DOI: 10.1016/j.jpeds.2011.09.035] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Revised: 08/08/2011] [Accepted: 09/21/2011] [Indexed: 10/15/2022]
Abstract
OBJECTIVE To characterize the changes in brown adipose tissue (BAT) occurring during puberty in boys and girls. STUDY DESIGN We examined the prevalence and the volume of BAT at different stages of sexual development in 73 pediatric patients who underwent positron emission tomography (PET)/computed tomography (CT) studies. RESULTS Of the 73 patients studied, 43 (59%) had BAT depicted on PET/CT. The presence of BAT was detected significantly less frequently on PET/CT in prepubertal subjects (Tanner stage 1) than in pubertal subjects (Tanner stages 2-5) (15% vs 75%). BAT volume also increased during puberty, with a significantly greater magnitude of the increase in the final 2 stages of puberty (Tanner stages 4 and 5) than in earlier stages (Tanner stages 1-3) (boys: 499 ± 246 vs 50 ± 36, P < .0001; girls: 286 ± 139 vs 36 ± 29, P = .024). Changes in BAT volume were also significantly greater in boys than in girls (P = .004) and were closely related to muscle volume (r = 0.52, P < .01 for boys; r = 0.64, P < .01 for girls). CONCLUSION The presence and volume of BAT increase rapidly during puberty. Metabolic and hormonal events related to the achievement of sexual maturity are likely responsible for this increase.
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Affiliation(s)
- Vicente Gilsanz
- Department of Radiology, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA 90027, USA.
| | - Michelle L. Smith
- Department of Radiology, Childrens Hospital Los Angeles, Keck School of Medicine
| | - Fariba Goodarzian
- Department of Radiology, Childrens Hospital Los Angeles, Keck School of Medicine
,Department of Pediatrics, Childrens Hospital Los Angeles, Keck School of Medicine
| | - Mimi Kim
- Department of Pediatrics, Childrens Hospital Los Angeles, Keck School of Medicine
,Division of Endocrinology and Metabolism, Childrens Hospital Los Angeles, Keck School of Medicine
| | - Tishya A. L. Wren
- Department of Radiology, Childrens Hospital Los Angeles, Keck School of Medicine
,Department of Orthopaedic Surgery, Childrens Hospital Los Angeles, Keck School of Medicine
| | - Houchun H. Hu
- Department of Radiology, Childrens Hospital Los Angeles, Keck School of Medicine
,Department of Electrical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90027
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Pace L, Nicolai E, D'Amico D, Ibello F, Della Morte AM, Salvatore B, Pizzuti LM, Salvatore M, Soricelli A. Determinants of physiologic 18F-FDG uptake in brown adipose tissue in sequential PET/CT examinations. Mol Imaging Biol 2012; 13:1029-35. [PMID: 20852948 DOI: 10.1007/s11307-010-0431-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
PURPOSE The aim of this study was to assess independent predictors of 2-deoxy-2-[(18)F]fluoro-D-glucose ((18)F-FDG) uptake in brown adipose tissue (BAT) in patients undergoing repeated positron emission tomography (PET)/computed tomography (CT) scans. PROCEDURES Eight hundred forty-eight (mean age 50.9 ± 16 years) patients in whom PET/CT scan was repeated (mean interval 5 ± 1.5 months) constituted the study group. (18)F-FDG uptake in characteristic areas of BAT, with CT density of adipose tissue, greater than background soft-tissue activity was considered as evidence of BAT uptake. Both distribution and maximum standardized uptake values (SUVmax) were registered. Clinical and anamnestic data were collected for each patient. RESULTS (18)F-FDG uptake in BAT was present in 8.6% patients at first scan. Independent predictors of presence of uptake were age (younger), gender (female), body mass index (lower), and maximum outdoor temperature (lower). Age was the only independent predictor of BAT (18)F-FDG uptake distribution, while SUVmax was related to both age and outdoor temperature. Independent determinants of persistence of BAT (18)F-FDG uptake at second PET/CT were outdoor temperature at time of second scan and extension of metabolically active BAT at first scan. CONCLUSIONS Age, body mass index, and outdoor temperature are significant determinants of BAT evidence at (18)F-FDG PET/CT. Moreover, extension of BAT and outdoor temperature are the strongest determinants of persistence of BAT evidence on (18)F-FDG PET/CT in repeated scan.
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Affiliation(s)
- Leonardo Pace
- Dipartimento di Scienze Biomorfologiche e Funzionali, Facoltà di Medicina e Chirurgia, Università degli Studi di Napoli Federico II, Napoli, Italy.
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Abstract
Thermogenesis, the production of heat energy, is an essential component of the homeostatic repertoire to maintain body temperature during the challenge of low environmental temperature and plays a key role in elevating body temperature during the febrile response to infection. Mitochondrial oxidation in brown adipose tissue (BAT) is a significant source of neurally regulated metabolic heat production in many species from mouse to man. BAT thermogenesis is regulated by neural networks in the central nervous system which responds to feedforward afferent signals from cutaneous and core body thermoreceptors and to feedback signals from brain thermosensitive neurons to activate BAT sympathetic nerve activity. This review summarizes the research leading to a model of the feedforward reflex pathway through which environmental cold stimulates BAT thermogenesis and includes the influence on this thermoregulatory network of the pyrogenic mediator, prostaglandin E(2), to increase body temperature during fever. The cold thermal afferent circuit from cutaneous thermal receptors, through second-order thermosensory neurons in the dorsal horn of the spinal cord ascends to activate neurons in the lateral parabrachial nucleus which drive GABAergic interneurons in the preoptic area (POA) to inhibit warm-sensitive, inhibitory output neurons of the POA. The resulting disinhibition of BAT thermogenesis-promoting neurons in the dorsomedial hypothalamus activates BAT sympathetic premotor neurons in the rostral ventromedial medulla, including the rostral raphe pallidus, which provide excitatory, and possibly disinhibitory, inputs to spinal sympathetic circuits to drive BAT thermogenesis. Other recently recognized central sites influencing BAT thermogenesis and energy expenditure are also described.
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Affiliation(s)
- Shaun F. Morrison
- Department of Neurological Surgery, Oregon Health and Science UniversityPortland, OR, USA
- *Correspondence: Shaun F. Morrison, Neurological Surgery, Oregon Health and Science University, 3181 South West Sam Jackson Park Road, Portland, OR 97239, USA. e-mail:
| | - Christopher J. Madden
- Department of Neurological Surgery, Oregon Health and Science UniversityPortland, OR, USA
| | - Domenico Tupone
- Department of Neurological Surgery, Oregon Health and Science UniversityPortland, OR, USA
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Boss O, Farmer SR. Recruitment of brown adipose tissue as a therapy for obesity-associated diseases. Front Endocrinol (Lausanne) 2012; 3:14. [PMID: 22654854 PMCID: PMC3356088 DOI: 10.3389/fendo.2012.00014] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Accepted: 01/17/2012] [Indexed: 01/23/2023] Open
Abstract
Brown adipose tissue (BAT) has been recognized for more than 20 years to play a key role in cold-induced non-shivering thermogenesis (CIT, NST), and body weight homeostasis in animals. BAT is a flexible tissue that can be recruited by stimuli (including small molecules in animals), and atrophies in the absence of a stimulus. In fact, the contribution of BAT (and UCP1) to resting metabolic rate and healthy body weight homeostasis in animals (rodents) is now well established. Many investigations have shown that resistance to obesity and associated disorders in various rodent models is due to increased BAT mass and the number of brown adipocytes or UCP1 expression in various depots. The recent discovery of active BAT in adult humans has rekindled the notion that BAT is a therapeutic target for combating obesity-related metabolic disorders. In this review, we highlight investigations performed in rodents that support the contention that activation of BAT formation and/or function in obese individuals is therapeutically powerful. We also propose that enhancement of brown adipocyte functions in white adipose tissue (WAT) will also regulate energy balance as well as reduce insulin resistance in obesity-associated inflammation in WAT.
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Affiliation(s)
- Olivier Boss
- Energesis Pharmaceuticals, Inc.Cambridge, MA, USA
| | - Stephen R. Farmer
- Department of Biochemistry, Boston University School of MedicineBoston, MA, USA
- *Correspondence: Stephen R. Farmer, Department of Biochemistry, Boston University School of Medicine, 72 East Concord Street, Boston, MA 02118, USA. e-mail:
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Klingenspor M, Herzig S, Pfeifer A. Brown fat develops a brite future. Obes Facts 2012; 5:890-6. [PMID: 23296106 DOI: 10.1159/000346337] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 12/10/2012] [Indexed: 01/02/2023] Open
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FDG Uptake in Lipomatous Hypertrophy of the Interatrial Septum Is Not Likely Related to Brown Adipose Tissue. Clin Nucl Med 2011; 36:767-9. [DOI: 10.1097/rlu.0b013e318219b353] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Donswijk ML, Broekhuizen-de Gast HS, Torigian DA, Alavi A, Kwee TC, Lam MG. PET Assessment of Brown Fat. PET Clin 2011; 6:365-75. [DOI: 10.1016/j.cpet.2011.04.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Hong TS, Shammas A, Charron M, Zukotynski KA, Drubach LA, Lim R. Brown adipose tissue 18F-FDG uptake in pediatric PET/CT imaging. Pediatr Radiol 2011; 41:759-68. [PMID: 21161205 DOI: 10.1007/s00247-010-1925-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Revised: 10/31/2010] [Accepted: 11/11/2010] [Indexed: 12/21/2022]
Abstract
Positron emission tomography (PET) using [F-18]2-fluoro-2-deoxyglucose (FDG) fused with CT ((18)F-FDG PET/CT) has been widely adopted in oncological imaging. However, it is known that benign lesions and other metabolically active tissues, such as brown adipose tissue (BAT), can accumulate (18)F-FDG, potentially resulting in false-positive interpretation. Previous studies have reported that (18)F-FDG uptake in BAT is more common in children than in adults. We illustrate BAT FDG uptake in various anatomical locations in children and adolescents. We also review what is known about the effects of patient-related physical attributes and environmental temperatures on BAT FDG uptake, and discuss methods used to reduce BAT FDG uptake on (18)F-FDG PET.
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Affiliation(s)
- Terence S Hong
- Department of Diagnostic Imaging, The Hospital for Sick Children, Toronto, Canada
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Geisler JG. Targeting energy expenditure via fuel switching and beyond. Diabetologia 2011; 54:237-44. [PMID: 20953861 DOI: 10.1007/s00125-010-1932-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2010] [Accepted: 08/19/2010] [Indexed: 01/04/2023]
Abstract
Since over-nutrition accelerates the development of obesity, progression to type 2 diabetes, and the associated co-morbidity and mortality, there has been a keen interest in therapeutic interventions targeting mechanisms that may curb appetite, increase energy expenditure or at least attenuate insulin resistance. Over the past decade, numerous peri-mitochondrial targets in the de novo lipid synthesis pathway have been linked to an increase in energy expenditure and the drug development industry has pursued the gene products involved as candidates to develop drugs against. The basis of this link, and specifically the premise that lowering tissue and cellular malonyl-CoA can increase energy expenditure, is scrutinised here. The argument presented is that fuel switching as effected by changes in cellular malonyl-CoA concentrations will not trigger the mitochondria to increase energy expenditure because: (1) an increase in beta-oxidation by lowering respiratory exchange ratio (indicative of the metabolic fuel consumed) does not equal an increase in energy expenditure (how rapidly fuel is consumed); (2) the ATP:oxygen ratios (i.e. ATP energy made:oxygen required for the reaction) are similar when metabolising lipids (2.8) vs glucose (3.0); (3) substrate availability (NEFA) does not drive energy expenditure in vivo; and (4) the availability of ADP in the mitochondrial matrix determines the rate of energy expenditure, not the availability of fuel to enter the mitochondrial matrix. To increase mitochondrial energy expenditure, work must be done (exercise) and/or the mitochondrial proton leak must be enhanced, both of which increase availability of ADP. In fact, despite the historic taboo of chemical uncoupling, this mechanism validated in humans is closest on task to increasing whole-body energy expenditure. Chemical uncoupling mimics the naturally occurring phenomenon of proton leak, accelerating the metabolism of glucose and lipids. However, it is completely non-genomic (i.e. the target is a location, not a gene product) and is not associated with addiction or mood alterations common to satiety agents. A significant hurdle for drug development is to discover a safe mitochondrial uncoupler and to formulate it potentially as a pro-drug and/or oral pump, to avoid the issue of overdosing experienced in the 1930s. The potential therapeutic impact of such a compound for an over-nutritioned patient population could be profound. If effective, the mitochondrial uncoupler mechanism could resolve many of the associated diseases such as type 2 diabetes, hypertension, obesity, depression, sleep apnoea, non-alcoholic steatohepatitis, insulin resistance and hyperlipidaemia, therefore becoming a 'disease-modifying therapy'.
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Affiliation(s)
- J G Geisler
- Johnson & Johnson Pharmaceutical Research and Development, LLC, Metabolic Disease, Drug Discovery, Welsh & McKean Roads, Spring House, PA 19477, USA.
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Nedergaard J, Bengtsson T, Cannon B. Three years with adult human brown adipose tissue. Ann N Y Acad Sci 2011; 1212:E20-36. [DOI: 10.1111/j.1749-6632.2010.05905.x] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Betz MJ, Enerbäck S. Therapeutic prospects of metabolically active brown adipose tissue in humans. Front Endocrinol (Lausanne) 2011; 2:86. [PMID: 22649390 PMCID: PMC3355987 DOI: 10.3389/fendo.2011.00086] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Accepted: 11/12/2011] [Indexed: 12/23/2022] Open
Abstract
The world-wide obesity epidemic constitutes a severe threat to human health and wellbeing and poses a major challenge to health-care systems. Current therapeutic approaches, relying mainly on reduced energy intake and/or increased exercise energy expenditure, are generally of limited effectiveness. Previously believed to be present only in children, the existence of metabolically active brown adipose tissue (BAT) was recently demonstrated also in healthy human adults. The physiological role of BAT is to dissipate chemical energy, mainly from fatty acids, as heat to maintain body temperature in cold environments. Recent studies indicate that the activity of BAT is negatively correlated with overweight and obesity, findings that raise the exciting possibility of new and effective weight reduction therapies based on increased BAT energy expenditure, a process likely to be amenable to pharmacological intervention.
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Affiliation(s)
- Matthias J. Betz
- Department of Medical Genetics, Institute of Biomedicine, Sahlgrenska Academy, University of GöteborgGöteborg, Sweden
- Medizinische Klinik, Campus Innenstadt, Klinikum der Ludwig-Maximilians-Universität MünchenMunich, Germany
| | - Sven Enerbäck
- Department of Medical Genetics, Institute of Biomedicine, Sahlgrenska Academy, University of GöteborgGöteborg, Sweden
- *Correspondence: Sven Enerbäck, Department of Medical Genetics, Institute of Biomedicine, Sahlgrenska Academy, University of Göteborg, Medicinaregatan 9A, Box 440, Göteborg 40530, Sweden. e-mail:
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Ouellet V, Routhier-Labadie A, Bellemare W, Lakhal-Chaieb L, Turcotte E, Carpentier AC, Richard D. Outdoor temperature, age, sex, body mass index, and diabetic status determine the prevalence, mass, and glucose-uptake activity of 18F-FDG-detected BAT in humans. J Clin Endocrinol Metab 2011; 96:192-9. [PMID: 20943785 DOI: 10.1210/jc.2010-0989] [Citation(s) in RCA: 399] [Impact Index Per Article: 30.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
CONTEXT In humans, the prevalence, mass, and glucose-uptake activity of (18)F-fluorodeoxyglucose ((18)F-FDG)-detected brown adipose tissue (BAT), which are expectedly enhanced by a cold stimulus, also appear modulated by other factors that still have to be disentangled. OBJECTIVE The objective of the study was to investigate the factors determining the prevalence, mass, and glucose-uptake activity of (18)F-FDG-detected BAT in humans. RESEARCH DESIGN AND METHODS We retrospectively analyzed all (18)F-FDG positron emission tomography/computed tomography examinations performed between January 2007 and December 2008 at our institution for (18)F-FDG uptake within the cervical/supraclavicular, mediastinal, paravertebral, and perirenal fat areas. The influence of outdoor temperature, sex, age, body mass index (BMI), plasma glucose level, diabetes diagnosis, day length, and cancer status on the prevalence, mass, and glucose-uptake activity of (18)F-FDG-detected BAT depots was investigated. RESULTS Three hundred twenty-eight of the 4842 patients (6.8%) had (18)F-FDG-detected BAT. The prevalence of (18)F-FDG BAT was negatively associated with outdoor temperature (P < 0.0001), age (P < 0.0001), BMI (P < 0.0001), and diabetes status (P = 0.0003). Moreover, there was a significant age × sex interaction for the prevalence of (18)F-FDG BAT (the younger the subjects, the greater the sex difference). The mass and glucose-uptake activity of (18)F-FDG-detected BAT also decreased with increasing outdoor temperature (P < 0.0001), age (P < 0.0001), and BMI (P < 0.0001). They were lower in men than in women (P < 0.001) and lower in diabetic than in nondiabetic patients (P = 0.0002). CONCLUSIONS The present study identifies outdoor temperature, age, sex, BMI, and diabetes status as determinants of the prevalence, mass, and glucose-uptake activity of (18)F-FDG-detected BAT.
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Affiliation(s)
- Veronique Ouellet
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Faculty of Medicine, Université Laval, Québec, Québec, Canada
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Esen Akkas B, Gökaslan D, Güner L, Ilgin Karabacak N. FDG uptake in brown adipose tissue—A brief report on brown fat with FDG uptake mechanisms and quantitative analysis using dual-time-point FDG PET/CT. ACTA ACUST UNITED AC 2011; 30:14-8. [DOI: 10.1016/j.remn.2010.05.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Revised: 05/12/2010] [Accepted: 05/26/2010] [Indexed: 11/29/2022]
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Abstract
New targets for pharmacological interventions are of great importance to combat the epidemic of obesity. Brown adipose tissue could potentially represent one such target. Unlike white adipose tissue, brown adipose tissue has the ability to dissipate energy by producing heat rather than storing it as triglycerides. In small mammals, the presence of active brown adipose tissue is pivotal for the maintenance of body temperature and possibly to protect against the detrimental effects of surplus energy intake. Animal studies have shown that expansion and/or activation of brown adipose tissue counteracts diet-induced weight gain and related disorders such as type 2 diabetes mellitus. Several independent studies have now confirmed the presence of functional brown adipose tissue in adult humans, for whom this tissue is probably metabolically beneficial given its association with both low BMI and low total adipose tissue content. Over the past few years, knowledge of the transcriptional control and development of brown adipose tissue has increased substantially. Thus, several possible targets that may be useful for the expansion and/or activation of this tissue by pharmacological means have been identified. Whether or not brown adipose tissue will be useful in the battle against obesity remains to be seen. However, this possibility is certainly well worth exploring.
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Affiliation(s)
- Martin E Lidell
- Department of Medical and Clinical Genetics, Institute of Biomedicine, University of Gothenburg, Box 440, SE-40530 Gothenburg, Sweden
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Terrien J, Ambid L, Nibbelink M, Saint-Charles A, Aujard F. Non-shivering thermogenesis activation and maintenance in the aging gray mouse lemur (Microcebus murinus). Exp Gerontol 2010; 45:442-8. [DOI: 10.1016/j.exger.2010.03.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2009] [Revised: 02/15/2010] [Accepted: 03/17/2010] [Indexed: 10/19/2022]
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Zukotynski KA, Fahey FH, Laffin S, Davis R, Treves ST, Grant FD, Drubach LA. Seasonal variation in the effect of constant ambient temperature of 24 degrees C in reducing FDG uptake by brown adipose tissue in children. Eur J Nucl Med Mol Imaging 2010; 37:1854-60. [PMID: 20505932 DOI: 10.1007/s00259-010-1485-2] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2010] [Accepted: 04/18/2010] [Indexed: 11/28/2022]
Abstract
PURPOSE It has been shown that warming patients prior to and during (18)F-FDG uptake by controlling the room temperature can decrease uptake by brown adipose tissue (BAT). The aim of this study is to determine if this effect is subject to seasonal variation. METHODS A retrospective review was conducted of all patients referred for whole-body (18)F-FDG PET between December 2006 and December 2008. After December 2007, all patients were kept in the PET injection room at a constant 24 degrees C for 30 min before and until 1 h following FDG administration. Patients over 22 years of age and those who received pre-medication known to reduce FDG uptake by BAT were excluded. One hundred and three patients were warmed to 24 degrees C prior to scanning. The number of patients showing uptake by BAT in this group was compared to a control group of 99 patients who underwent PET prior to December 2007 when the injection room temperature was 21 degrees C. RESULTS Uptake by BAT occurred in 9% of studies performed after patient warming (24 degrees C), compared to 27% of studies performed on the control group (21 degrees C) (p < 0.00001). The effect of warming on decreasing FDG accumulation in BAT was statistically significant in the winter (p < 0.005) and summer (p < 0.001). However, in the spring and autumn, though the effect of warming on decreasing FDG accumulation in BAT was evident, it was not statistically significant (p > 0.05). CONCLUSION Maintaining room temperature at a constant 24 degrees C for 30 min prior to and 1 h after IV tracer administration significantly decreases FDG uptake by BAT in children. This effect is greatest in the summer and winter.
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Affiliation(s)
- Katherine A Zukotynski
- Department of Imaging, Division of Nuclear Medicine, Dana-Farber Cancer Institute, Harvard Medical School, 44 Binney Street, Boston, MA 02115, USA.
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Paes FM, Kalkanis DG, Sideras PA, Serafini AN. FDG PET/CT of extranodal involvement in non-Hodgkin lymphoma and Hodgkin disease. Radiographics 2010; 30:269-91. [PMID: 20083598 DOI: 10.1148/rg.301095088] [Citation(s) in RCA: 198] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The term extranodal disease refers to lymphomatous infiltration of anatomic sites other than the lymph nodes. Almost any organ can be affected by lymphoma, with the most common extranodal sites of involvement being the stomach, spleen, Waldeyer ring, central nervous system, lung, bone, and skin. The prevalence of extranodal involvement in non-Hodgkin lymphoma and Hodgkin disease has increased in the past decade. The imaging characteristics of extranodal involvement can be subtle or absent at conventional computed tomography (CT). Imaging of tumor metabolism with 2-[fluorine-18]fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET) has facilitated the identification of affected extranodal sites, even when CT has demonstrated no lesions. More recently, hybrid PET/CT has become the standard imaging modality for initial staging, follow-up, and treatment response assessment in patients with lymphoma and has proved superior to CT in these settings. Certain PET/CT patterns are suggestive of extranodal disease and can help differentiate tumor from normal physiologic FDG activity, particularly in the mucosal tissues, bone marrow, and organs of the gastrointestinal tract. Familiarity with the different extranodal manifestations in various locations is critical for correct image interpretation. In addition, a knowledge of the differences in FDG avidity among the histologic subtypes of lymphoma, appropriate timing of scanning after therapeutic interventions, and use of techniques to prevent brown fat uptake are essential for providing the oncologist with accurate information.
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Affiliation(s)
- Fabio M Paes
- Department of Radiology, Division of Nuclear Medicine, Jackson Memorial Hospital, University of Miami and Miller School of Medicine, 1080 NW 19th Street, Miami, FL 33136, USA.
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Baba S, Jacene HA, Engles JM, Honda H, Wahl RL. CT Hounsfield Units of Brown Adipose Tissue Increase with Activation: Preclinical and Clinical Studies. J Nucl Med 2010; 51:246-50. [DOI: 10.2967/jnumed.109.068775] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Abstract
OBJECTIVE The purpose of this article is to review the physiology and describe the typical and atypical presentations of brown fat on (18)F-FDG PET. CONCLUSION The presence of brown fat on FDG PET has the potential to lead to misinterpretation and unneeded invasive tests, which can be avoided by using measures such as ensuring the patient is warm, reducing FDG uptake in brown fat before the procedure, and correlating PET uptake to a specific anatomic location with PET/CT fusion imaging.
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AGRAWAL A, NAIR N, BAGHEL NS. A novel approach for reduction of brown fat uptake on FDG PET. Br J Radiol 2009; 82:626-31. [PMID: 19188245 DOI: 10.1259/bjr/24661539] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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Saito M, Okamatsu-Ogura Y, Matsushita M, Watanabe K, Yoneshiro T, Nio-Kobayashi J, Iwanaga T, Miyagawa M, Kameya T, Nakada K, Kawai Y, Tsujisaki M. High incidence of metabolically active brown adipose tissue in healthy adult humans: effects of cold exposure and adiposity. Diabetes 2009; 58:1526-31. [PMID: 19401428 PMCID: PMC2699872 DOI: 10.2337/db09-0530] [Citation(s) in RCA: 1431] [Impact Index Per Article: 95.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
OBJECTIVE The significant roles of brown adipose tissue (BAT) in the regulation of energy expenditure and adiposity are established in small rodents but have been controversial in humans. The objective is to examine the prevalence of metabolically active BAT in healthy adult humans and to clarify the effects of cold exposure and adiposity. RESEARCH DESIGN AND METHODS In vivo 2-[(18)F]fluoro-2-deoxyglucose (FDG) uptake into adipose tissue was measured in 56 healthy volunteers (31 male and 25 female subjects) aged 23-65 years by positron emission tomography (PET) combined with X-ray computed tomography (CT). RESULTS When exposed to cold (19 degrees C) for 2 h, 17 of 32 younger subjects (aged 23-35 years) and 2 of 24 elderly subjects (aged 38-65 years) showed a substantial FDG uptake into adipose tissue of the supraclavicular and paraspinal regions, whereas they showed no detectable uptake when kept warm (27 degrees C). Histological examinations confirmed the presence of brown adipocytes in these regions. The cold-activated FDG uptake was increased in winter compared with summer (P < 0.001) and was inversely related to BMI (P < 0.001) and total (P < 0.01) and visceral (P < 0.001) fat areas estimated from CT image at the umbilical level. CONCLUSIONS Our findings, being against the conventional view, indicate the high incidence of metabolically active BAT in adult humans and suggest a role in the control of body temperature and adiposity.
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Affiliation(s)
- Masayuki Saito
- Department of Nutrition, School of Nursing and Nutrition, Tenshi College, Sapporo, Japan.
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Zingaretti MC, Crosta F, Vitali A, Guerrieri M, Frontini A, Cannon B, Nedergaard J, Cinti S. The presence of UCP1 demonstrates that metabolically active adipose tissue in the neck of adult humans truly represents brown adipose tissue. FASEB J 2009; 23:3113-20. [PMID: 19417078 DOI: 10.1096/fj.09-133546] [Citation(s) in RCA: 569] [Impact Index Per Article: 37.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Classically, adult humans have been considered not to possess active brown adipose tissue (BAT). However, positron-emission-tomography has shown fluorodeoxyglucose uptake that is distributed in such a way (e.g., in the neck) that it would seem to be BAT. Until now this has not been supported by direct evidence that these areas truly represented BAT, that is, the presence of the BAT-unique uncoupling protein-1 (UCP1). Samples of adipose tissue from the neck of 35 patients undergoing surgery for thyroid diseases were obtained and analyzed. In 1/3 of the subjects (the younger and leaner), distinct islands composed of UCP1 immunoreactive brown adipocytes could clearly be discerned, accounting for up to 1/3 of all adipocytes. The brown-adipose islands were richly sympathetically innervated (indicating acute central control); adjacent white adipose areas were not. The capillary density was high, implying a high capacity for oxygen delivery. Cells with features of brown adipocyte precursors were found in pericapillary areas. These data demonstrate that human adults indeed possess BAT and thus imply possibilities of future therapeutic strategies for the treatment of obesity, including maintenance of brown adipocytes and stimulation of the growth of preexisting brown precursors.
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Affiliation(s)
- Maria Cristina Zingaretti
- Department of Molecular Pathology and Innovative Therapies, Faculty of Medicine, Ospedali Riuniti Ancona, University of Ancona (Politecnica delle Marche), Ancona, Italy
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Abstract
The ability to not only replicate but also extend the findings from both historical epidemiological studies and contemporary cohorts of the developmental programming of later disease are critical if the mechanisms by which early diet impacts on later disease are to be fully understood. To date, a plethora of models have been established, with the range including global changes in dietary input, imbalanced diets and diets deficient in single nutrients. Key factors in translating these findings to the human situation are the pronounced differences in the relative growth and development between large and small mammals from the time of conception through pregnancy, lactation and weaning. This disparity is reflected in the very different nutritional requirements between species and the substantial divergence between rodents and large animals in the ontogeny of many of the organ systems that are nutritionally regulated. For example, hypothalamic circuitry is much more developed in species with a long gestation and offspring are born with a mature hypothalamic-pituitary axis in sheep and man compared with mice and rats. Similarly, nephron number is established towards the end of gestation in large mammals compared with the lactational period in rats. These types of differences will impact on the ability of individual and combined nutritional interventions to reset developmental processes, and may be further compounded by the gender of a fetus. The challenge for future work in this exciting and dynamic area of research is to utilise these marked comparative differences to generate imaginative nutritional interventions in order to improve the viability, health and well-being of the offspring.
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Abstract
Mitochondrial uncoupling protein 1 (UCP1) is a key regulator of adaptive thermogenesis and energy expenditure. Mice lacking UCP1 are cold sensitive, but surprisingly not obese at room temperature. In this issue of Cell Metabolism, Feldmann et al. (2009) unmask an obesogenic phenotype by simply maintaining these mice at thermoneutrality.
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Zukotynski KA, Fahey FH, Laffin S, Davis R, Treves ST, Grant FD, Drubach LA. Constant ambient temperature of 24 degrees C significantly reduces FDG uptake by brown adipose tissue in children scanned during the winter. Eur J Nucl Med Mol Imaging 2008; 36:602-6. [PMID: 19037639 DOI: 10.1007/s00259-008-0983-y] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2008] [Accepted: 10/03/2008] [Indexed: 11/25/2022]
Abstract
PURPOSE The aim of this study was to determine if warming patients prior to and during (18)F-FDG uptake by controlling the room temperature could decrease uptake by brown adipose tissue (BAT). METHODS A group of 40 children underwent (18)F-FDG PET after being kept in the injection room at a constant temperature of 24 degrees C for half an hour before and 1 hour after intravenous tracer administration. The rate of uptake by BAT in this group was compared to the uptake in a control group of 45 patients who underwent PET when the injection room temperature was 21 degrees C. RESULTS Uptake by BAT occurred in 5% of studies in the temperature-controlled room compared to 31% of studies performed when the injection room temperature was 21 degrees C (p<0.002). CONCLUSION Maintaining room temperature at a constant 24 degrees C, half an hour prior to and during the period of FDG uptake significantly decreases accumulation of FDG in BAT in children.
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Affiliation(s)
- Katherine A Zukotynski
- Department of Radiology, Division of Nuclear Medicine/PET, Children's Hospital Boston, Harvard Medical School, Boston, MA 02115, USA
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Potential false positive Tc-99m sestamibi parathyroid study due to uptake in brown adipose tissue. Clin Nucl Med 2008; 33:346-8. [PMID: 18431153 DOI: 10.1097/rlu.0b013e31816a795a] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We report on a 55-year-old woman with suspected primary hyperparathyroidism who underwent dual phase Tc-99m sestamibi parathyroid imaging. Symmetric, patchy activity in the neck and shoulders was localized to low attenuation areas on integrated SPECT/CT and attributed to uptake in brown adipose tissue (BAT). Focal uptake in the anterior thorax on SPECT images, which potentially may have been misinterpreted as ectopic parathyroid tissue, was demonstrated on SPECT/CT as uptake in BAT. Recognition of this pattern on parathyroid SPECT/CT scintigraphy may avoid false positive reports. Our case provides further evidence that in addition to F-18 FDG, I-123 MIBG, and Tc-99m tetrofosmin, Tc-99m sestamibi may also accumulate in BAT.
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Abstract
Thermogenesis, the production of heat energy, is an essential component of the homeostatic repertoire to maintain body temperature in mammals and birds during the challenge of low environmental temperature and plays a key role in elevating body temperature during the febrile response to infection. The primary sources of neurally regulated metabolic heat production are mitochondrial oxidation in brown adipose tissue, increases in heart rate and shivering in skeletal muscle. Thermogenesis is regulated in each of these tissues by parallel networks in the central nervous system, which respond to feedforward afferent signals from cutaneous and core body thermoreceptors and to feedback signals from brain thermosensitive neurons to activate the appropriate sympathetic and somatic efferents. This review summarizes the research leading to a model of the feedforward reflex pathway through which environmental cold stimulates thermogenesis and discusses the influence on this thermoregulatory network of the pyrogenic mediator, prostaglandin E(2), to increase body temperature. The cold thermal afferent circuit from cutaneous thermal receptors ascends via second-order thermosensory neurons in the dorsal horn of the spinal cord to activate neurons in the lateral parabrachial nucleus, which drive GABAergic interneurons in the preoptic area to inhibit warm-sensitive, inhibitory output neurons of the preoptic area. The resulting disinhibition of thermogenesis-promoting neurons in the dorsomedial hypothalamus and possibly of sympathetic and somatic premotor neurons in the rostral ventromedial medulla, including the raphe pallidus, activates excitatory inputs to spinal sympathetic and somatic motor circuits to drive thermogenesis.
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Affiliation(s)
- Shaun F Morrison
- Neurological Sciences Institute, Oregon Health & Science University, 505 NW 185th Avenue, Beaverton, OR 97006, USA.
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