Béatrice Morio

Hibernoma: A Clinical Model for Exploring the Role of Brown Adipose Tissue in the Regulation of Body Weight?

CONTEXTnHibernoma is a rare benign tumor histologically similar to brown adipose tissue. Some studies reported weight loss in patients with this tumor; however, the mechanisms have never been investigated.nnnOBJECTIVEnThe purpose of this study is to explore the impact of hibernoma resection on the whole-body metabolism.nnnPATIENT AND METHODSnA 68-year-old woman was examined after a weight loss of 10 kg in 6 months. Body composition, food intake, physical activity, blood levels of thyroid hormones, and lipid profile were assessed before surgery and during 1 year after surgery. The patients resting energy expenditure (REE) over time was compared to a control group of 18 matched healthy volunteers.nnnRESULTSnWithin 1 year after hibernoma resection, the patient gained 15 kg of body weight. This was associated with fat mass gain (+41%), mainly in the abdominal region (+48%). The patient also developed hepatic nonalcoholic steatosis, mild hypertriglyceridemia, and reduced levels of high-density lipoproteins. REE increased during the dynamic phase of weight gain, compared to the presurgery measurement, and returned to baseline after 1 year. Food intake was increased by 37.5% 6 weeks after resection of the hibernoma and returned to baseline values within 6 months.nnnCONCLUSIONSnIn our study conditions, hibernoma did not alter REE, but weight gain did. Specific physical activities and dietetic follow-ups are suggested for those patients to prevent excess fat mass gain and metabolic disorders after hibernoma resection. More studies should focus on hibernoma mechanisms inducing weight loss.

Brown Adipose Tissue Activity in Relation to Weight Gain During Chemotherapy in Breast Cancer Patients: A Pilot Study

Weight gain has been reported in early stage breast cancer patients during chemotherapy, but the involved mechanisms remain unclear. A chemotherapy-induced decrease of brown adipose tissue (BAT) activity may partly contribute to weight gain in these patients. A positron emission tomography/computed tomography scan was performed at baseline and after 1 course of docetaxel + trastuzumab treatment in 26 breast cancer women. Variation of the maximal standardized uptake value of BAT in the cervical and supraclavicular regions between the 2 measures was assessed according to weight changes. Overall, 18F-FDG uptakes in BAT decreased by 11.3% after 1 course of chemotherapy (p = 0.03). No correlation was found between the baseline values of 18F-FDG uptake and body mass index or age of patients, but as expected 18F-FDG uptake was dependent on season period. Among the patients, 35% gained weight, 25% lost weight, and 40% remained stable. Women who gained weight during chemotherapy experienced a significant decrease of 18F-FDG uptake in BAT (p = 0.005). Decreased activity of BAT was associated with body weight gain during chemotherapy. These original data suggest for the first time that BAT modulation by chemotherapy would be a potential contributor to body weight gain through blunted thermogenesis in breast cancer patients.

Evaluation of Mitochondrial Functions and Dysfunctions in Muscle Biopsy Samples

Within the past decade, the list of publications involving mitochondrial dysfunction in the etiology of metabolic disorders in obesity, insulin resistance and type 2 diabetes, has been growing steadily. Today, large controversies still exist and it is clear that the understanding of the causes and consequences of impairments in mitochondrial functioning are far from being accomplished. In this context, our purpose is to review techniques used in human samples to highlight defects in mitochondrial activity, with a particular focus on skeletal muscle. Several tools are described to assess a large array of mitochondrial functions. In order to facilitate the reading of the review, several details related to methodological concerns are provided in supplementary materials and remain available upon request to the authors.