| 1. |
- Borga, Magnus, et al.
(författare)
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Brown adipose tissue in humans: detection and functional analysis using PET (positron emission tomography), MRI (magnetic resonance imaging), and DECT (dual energy computed tomography).
- 2014
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Ingår i: Methods in enzymology. - : Elsevier. - 1557-7988. ; 537, s. 141-59, s. 141-159
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Tidskriftsartikel (refereegranskat)abstract
- If the beneficial effects of brown adipose tissue (BAT) on whole body metabolism, as observed in nonhuman experimental models, are to be translated to humans, tools that accurately measure how BAT influences human metabolism will be required. This chapter discusses such techniques, how they can be used, what they can measure and also some of their limitations. The focus is on detection and functional analysis of human BAT and how this can be facilitated by applying advanced imaging technology such as positron emission tomography, magnetic resonance imaging, and dual energy computed tomography.
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| 2. |
- Chondronikola, M., et al.
(författare)
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Brown Adipose Tissue Improves Whole-Body Glucose Homeostasis and Insulin Sensitivity in Humans
- 2014
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 63:12, s. 4089-4099
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Tidskriftsartikel (refereegranskat)abstract
- Brown adipose tissue (BAT) has attracted scientific interest as an antidiabetic tissue owing to its ability to dissipate energy as heat. Despite a plethora of data concerning the role of BAT in glucose metabolism in rodents, the role of BAT (if any) in glucose metabolism in humans remains unclear. To investigate whether BAT activation alters whole-body glucose homeostasis and insulin sensitivity in humans, we studied seven BAT-positive (BAT(+)) men and five BAT-negative (BAT(-)) men under thermoneutral conditions and after prolonged (5-8 h) cold exposure (CE). The two groups were similar in age, BMI, and adiposity. CE significantly increased resting energy expenditure, whole-body glucose disposal, plasma glucose oxidation, and insulin sensitivity in the BAT+ group only. These results demonstrate a physiologically significant role of BAT in whole-body energy expenditure, glucose homeostasis, and insulin sensitivity in humans, and support the notion that BAT may function as an antidiabetic tissue in humans.
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| 3. |
- Enerbäck, Sven, 1958
(författare)
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An enzymatic chromatin switch that directs formation of active brown fat
- 2014
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Ingår i: Cell Metabolism. - : Elsevier BV. - 1550-4131 .- 1932-7420. ; 19:1, s. 3-4
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Tidskriftsartikel (refereegranskat)abstract
- How is the recruitment of brown adipocytes regulated? Ohno et al. (2013) show that the euchromatic histone-lysine N-metyltransferase 1 (EHMT1) is essential for the specification of the brown adipocyte fate, a finding with important implications for the pathophysiology of obesity and obesity-related maladies. © 2014 Elsevier Inc.
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| 4. |
- Gnad, T., et al.
(författare)
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Adenosine activates brown adipose tissue and recruits beige adipocytes via A(2A) receptors
- 2014
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 516:7531
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Tidskriftsartikel (refereegranskat)abstract
- Brown adipose tissue (BAT) is specialized in energy expenditure, making it a potential target for anti-obesity therapies(1-5). Following exposure to cold, BAT is activated by the sympathetic nervous system with concomitant release of catecholamines and activation of beta-adrenergic receptors(1-5). Because BAT therapies based on cold exposureor beta-adrenergic agonists are clinically not feasible, alternative strategies must be explored. Purinergic co-transmission might be involved in sympathetic control of BAT and previous studies reported inhibitory effects of the purinergic transmitter adenosine in BAT from hamster or rat(6-8). However, the role of adenosine in human BAT is unknown. Here we show that adenosine activates human and murine brown adipocytes at low nanomolar concentrations. Adenosine is released in BAT during stimulation of sympathetic nerves as well as from brown adipocytes. The adenosine A(2A) receptor is the most abundant adenosine receptor in human and murine BAT. Pharmacological blockade or genetic loss of A(2A) receptors in mice causes adecrease in BAT-dependent thermogenesis, whereas treatment with A(2A) agonists significantly increases energy expenditure. Moreover, pharmacological stimulation of A(2A) receptors or injection of lentiviral vectors expressing the A(2A) receptor into white fat induces brown-like cells-so-called beige adipocytes. Importantly, mice fed a high-fat diet and treated with an A(2A) agonist are leaner with improved glucose tolerance. Taken together, our results demonstrate that adenosine-A(2A) signalling plays an unexpected physiological role in sympathetic BAT activation and protects mice from diet-induced obesity. Those findings reveal new possibilities for developing novel obesity therapies.
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| 5. |
- Lahesmaa, M., et al.
(författare)
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Hyperthyroidism increases brown fat metabolism in humans
- 2014
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 99:1
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Tidskriftsartikel (refereegranskat)abstract
- Context: Thyroid hormones are important regulators of brown adipose tissue (BAT) development and function. In rodents, BAT metabolism is up-regulated by thyroid hormones. Objective: The purpose of this article was to investigate the impact of hyperthyroidism on BAT metabolism in humans. Design: This was a follow-up study using positron emission tomography imaging. Main Outcome Measures: Glucose uptake (GU) and perfusion of BAT, white adipose tissue, skeletal muscle, and thyroid gland were measured using [18F]2-fluoro-2-deoxy-D- glucose and [15O]H2Oand positron emission tomography in 10 patients with overt hyperthyroidism and in 8 healthy participants. Five of the hyperthyroid patients were restudied after restoration of euthyroidism. Supraclavicular BAT was quantified with magnetic resonance imaging or computed tomography and energy expenditure (EE) with indirect calorimetry. Results: Compared with healthy participants, hyperthyroid participants had 3-fold higher BAT GU (2.7 ± 2.3 vs 0.9 ± 0.1 ±mol/100 g/min, P = .0013), 90% higher skeletal muscle GU (P < .005), 45% higher EE (P<.005), and a 70% higher lipid oxidation rate (P = .001). These changes were reversible after restoration of euthyroidism. During hyperthyroidism, serum free T4 and free T3 were strongly associated with EE and lipid oxidation rates (P < .001). TSH correlated inversely with BAT and skeletal muscle glucose metabolism (P < .001). Hyperthyroidism had no effect on BAT perfusion, whereas it stimulated skeletal muscle perfusion (P = .04). Thyroid gland GU did not differ between hyperthyroid and euthyroid study subjects. Conclusions: Hyperthyroidism increases GU in BAT independently of BAT perfusion. Hyperthyroid patients are characterized by increased skeletal muscle metabolism and lipid oxidation rates. (J Clin Endocrinol Metab 99: E28-E35, 2014). © Copyright 2014 by The Endocrine Society.
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| 6. |
- Lidell, Martin, 1970, et al.
(författare)
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Brown adipose tissue and its therapeutic potential
- 2014
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Ingår i: Journal of Internal Medicine. - : Wiley. - 0954-6820. ; 276:4, s. 364-377
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Tidskriftsartikel (refereegranskat)abstract
- Obesity and related diseases are a major cause of human morbidity and mortality and constitute a substantial economic burden for society. Effective treatment regimens are scarce, and new therapeutic targets are needed. Brown adipose tissue, an energy-expending tissue that produces heat, represents a potential therapeutic target. Its presence is associated with low body mass index, low total adipose tissue content and a lower risk of type 2 diabetes mellitus. Knowledge about the development and function of thermogenic adipocytes in brown adipose tissue has increased substantially in the last decade. Important transcriptional regulators have been identified, and hormones able to modulate the thermogenic capacity of the tissue have been recognized. Intriguingly, it is now clear that humans, like rodents, possess two types of thermogenic adipocytes: the classical brown adipocytes found in the interscapular brown adipose organ and the so-called beige adipocytes primarily found in subcutaneous white adipose tissue after adrenergic stimulation. The presence of two distinct types of energy-expending adipocytes in humans is conceptually important because these cells might be stimulated and recruited by different signals, raising the possibility that they might be separate potential targets for therapeutic intervention. In this review, we will discuss important features of the energy-expending brown adipose tissue and highlight those that may serve as potential targets for pharmacological intervention aimed at expanding the tissue and/or enhancing its function to counteract obesity.
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