Summary Brown adipose tissue (BAT) plays an important role in mammalian thermoregulation. The component of BAT mitochondria that permits this function is the inner membrane carrier protein uncoupling protein 1 (UCP1). To the best of our knowledge, no studies have directly quantified UCP1 function in human BAT. Further, whether human and rodent BAT have comparable thermogenic function remains unknown. We employed high-resolution respirometry to determine the respiratory capacity, coupling control, and most importantly, UCP1 function of human supraclavicular BAT and rodent interscapular BAT. Human BAT was sensitive to the purine nucleotide GDP, providing the first direct that human BAT mitochondria have thermogenically functional UCP1. Further, our data demonstrate that human and rodent BAT have similar UCP1 function per mitochondrion. These data indicate that human and rodent BAT are qualitatively similar in terms of UCP1 function.

Background The hypercatabolic response in severely burned pediatric patients is associated with increased production of catecholamines and corticosteroids, decreased formation of testosterone, and reduced strength alongside growth arrest for up to 2 years post injury. We have previously shown that, in the pediatric burned population, the administration of the testosterone analog oxandrolone improves lean body mass accretion and bone mineral content and that the administration of the β1, β2 adrenoreceptor antagonist propranolol decreases cardiac work and resting energy expenditure while increasing peripheral lean mass. Here, we determined whether the combined administration of oxandrolone and propranolol has added benefit. Methods In this prospective, randomized study of 612 burned children (52 ± 1% of total body surface area burned, ages 0.5–14 years [males]; ages 0.5–12 years [females]), we compared controls to the individual administration of these drugs, and the combined administration of oxandrolone and propranolol at the same doses, for 1 year post burn. Data were recorded at discharge, 6 months, and 1 and 2 years post injury. Results Combined use of oxandrolone and propranolol shortened the period of growth arrest by 84 days (p=0.0125 vs. control) and increased growth rate by 1.7 cm/y (p=0.0024 vs. control). Conclusion Combined administration of oxandrolone and propranolol attenuates burn-induced growth arrest in pediatric burn patients. This study is registered at clinicaltrials.gov: NCT00675714 and NCT00239668. Growth Arrest and Growth Rate By Treatment GroupTreatmentLength of Growth Arrest(Days)Growth Rate(cm/y)Control280 ± 195.9 ± 0.2Oxandrolone217 ± 175.8 ± 0.3Propranolol242 ± 136.3 ± 0.2Oxandrolone + Propranolol196 ± 15*7.6 ± 0.5*Data presented as mean ± standard error.*p<0.05 vs. control.