PET/MRI of glucose metabolic rate, lipid content and perfusion in human brown adipose tissue

This study evaluated the MRI-derived fat fraction (FF), from a Cooling-reheating protocol, for estimating the cold-induced brown adipose tissue (BAT) metabolic rate of glucose (MRglu) and changes in lipid content, perfusion and arterial blood volume (VA) within cervical-supraclavicular fat (sBAT). Twelve volunteers underwent PET/MRI at baseline, during cold exposure and reheating. For each temperature condition, perfusion and VA were quantified with dynamic [15O]water-PET, and FF, with water-fat MRI. MRglu was assessed with dynamic [18F]fluorodeoxyglucose-PET during cold exposure. sBAT was defined using anatomical criteria, and its subregion sBATHI, by MRglu > 11 μmol/100 cm3/min. For all temperature conditions, sBAT-FF correlated negatively with sBAT-MRglu (ρ ≤ − 0.87). After 3 h of cold, sBAT-FF decreased (− 2.13 percentage points) but tended to normalize during reheating although sBATHI-FF remained low. sBAT-perfusion and sBAT-VA increased during cold exposure (perfusion: + 5.2 ml/100 cm3/min, VA: + 4.0 ml/100 cm3). sBAT-perfusion remained elevated and sBAT-VA normalized during reheating. Regardless of temperature condition during the Cooling-reheating protocol, sBAT-FF could predict the cold-induced sBAT-MRglu. The FF decreases observed after reheating were mainly due to lipid consumption, but could potentially be underestimated due to intracellular lipid replenishment. The influence of perfusion and VA, on the changes in FF observed during cold exposure, could not be ruled out.

TRIVALENT CHROMIUM (CR+3) IN DIETARY CARBOHYDRATE AND ITS EFFECT ON THE GROWTH OF COMMONLY CULTIVATED FISH

Trivalent chromium (Cr+3) is an essential trace mineral for fish bio-physiological functions. Researches on Cr+3 in the form of organic compound indicated that the mineral affected the bio-activity of insulin, the blood glucose influx, and subsequently the blood glucose metabolic rate. By increasing the blood glucose metabolism, dietary carbohydrate will be more efficiently used as a main energy source, thereby, dietary protein couldbe efficiently retained as for somatic growth. Researches on various feeding habits of fish (e.g. gouramy-herbivorous fish, tilapia-omnivorous fish, and catfish-carnivorous fish) showed that dietary Cr+3 in certain amount increased diet utilization and the fish growth.