Activated brown adipose tissue and its relationship to adiposity and metabolic markers: an exploratory study.

Objective: To explore relationships between PET/CT characteristics of cold-activated brown adipose tissue (BAT), measures of adiposity and metabolic markers.Methods: We conducted a post-hoc analysis of a study which utilized PET/CT to characterize BAT. 25 men ages 18-24 (BMI 19.4 to 35.9 kg/m2) were studied. Fasting blood samples were collected. Body composition was measured using DXA. An individualized cooling protocol was utilized to activate BAT prior to imaging with PET/CT.Results: There was an inverse relationship between fasting serum glucose and BAT volume (r = -0.40, p = 0.048). A marginally significant inverse relationship was also noted between fasting glucose and total BAT activity (r = -0.40, p = 0.05). In addition, a positive correlation was observed between serum FGF21 and SUVmax (r = 0.51, p = 0.01). No significant correlations were noted for measures of BAT activity or volume and other indicators of adiposity or glucose metabolism.Conclusions: The presence of active BAT may be associated with lower fasting glucose in young men. BAT activity may also be correlated with levels of FGF21, suggesting that BAT may lower glucose levels via an FGF21 dependent pathway. Further studies are needed to clarify mechanisms by which BAT may impact glucose metabolism.

ECTOPIC ADRENOCORTICOTROPIC HORMONE SYNDROME DUE TO METASTATIC PROSTATE CANCER WITH NEUROENDOCRINE DIFFERENTIATION.

OBJECTIVE: Neuroendocrine differentiation of prostate cancer can result in ectopic adrenocorticotropic hormone (ACTH) secretion (EAS) and Cushing syndrome. The aim of this report is to highlight this unusual mechanism of hypercortisolism and its management. METHODS: We report a 73-year-old patient with a history of prostate adenocarcinoma who presented with severe weakness, hyperglycemia, and hypokalemia caused by EAS. RESULTS: Diagnostic workup showed elevated 24-hour urine cortisol and ACTH levels consistent with EAS. Fluorodeoxyglucose positron emission tomography-computed tomography revealed a hypermetabolic mass in the prostate and metastatic lesions to the liver and bones. Liver biopsy was consistent with small cell carcinoma with positive immunostaining for ACTH. Pleural fluid analysis was consistent with high-grade neuroendocrine carcinoma. The patient underwent chemotherapy with carboplatin and etoposide. Hypercortisolism was treated with ketoconazole, metyrapone, mifepristone, and spironolactone. He suffered complications including opportunistic infections, deep venous thrombosis, and delirium. Given his poor prognosis and clinical decline, the patient opted for comfort measures only in a hospice facility. CONCLUSION: Treatment-related neuroendocrine differentiation of prostate cancer is an emerging entity that may be associated with paraneoplastic syndromes including EAS.

CENTRAL DIABETES INSIPIDUS AND CHEMOTHERAPY: USE OF A CONTINUOUS ARGININE VASOPRESSIN INFUSION FOR FLUID AND SODIUM BALANCE.

OBJECTIVE: Central diabetes insipidus can occur in the setting of primary or metastatic tumors that disrupt the hypothalamic-pituitary axis. Usual treatment consists of water intake to replace ongoing fluid losses and desmopressin administration aimed at decreasing the urine output to enable maintenance of eunatremia without polyuria. Marked derangement in plasma sodium concentration can occur when high-volume intravenous fluid administration is required during chemotherapy to prevent nephrotoxicity, particularly if obligate fluid intake exceeds the total daily fluid intake necessary to maintain eunatremia. METHODS: We developed a protocol for a rapidly titratable low-dose continuous intravenous arginine vasopressin infusion to maintain eunatremia in patients with central diabetes insipidus during periods of obligate fluid intake. RESULTS: We successfully maintained eunatremia in 2 patients with central nervous system lymphoma who underwent several cycles of obligate intravenous fluid administration with 5% dextrose in 0.45% sodium chloride for chemotherapy. CONCLUSION: Obligate fluid administration can result in dangerous and severe fluctuations in plasma sodium concentration in patients with central diabetes insipidus receiving conventional desmopressin therapy. The use of a rapidly titratable low-dose continuous vasopressin infusion successfully maintained eunatremia in this setting. This protocol can be replicated to prevent the wide and potentially dangerous fluctuations in plasma sodium concentration that can occur in patients with central diabetes insipidus who require high-volume intravenous fluid administration. This protocol has not been assessed among patients with impaired renal function and, thus, may not be generalizable to this population. (AACE Clinical Case Rep. 2018;4:e487-e492).

Human respiratory mechanics demonstration model.

Respiratory mechanics is a difficult topic for instructors and students alike. Existing respiratory mechanics models are limited in their abilities to demonstrate any effects of rib cage movement on alveolar and intrapleural pressures. We developed a model that can be used in both large and small classroom settings. This model contains digital pressure displays and computer integration for real-time demonstration of pressure changes that correspond to the different phases of breathing. Moving the simulated diaphragm and rib cage causes a volume change that results in pressure changes visible on the digital sensors and computer display. Device testing confirmed the model's ability to accurately demonstrate pressure changes in proportion to physiological values. Classroom testing in 427 surveyed students showed improved understanding of respiratory concepts (P < 0.05). We conclude that our respiratory mechanics model is a valuable instructional tool and provide detailed instructions for those who would like to create their own.