Real-time cellular impedance monitoring and imaging of biological barriers in a dual-flow membrane bioreactor.

The generation of physiologically relevant in-vitro models of biological barriers can play a key role in understanding human diseases and in the development of more predictive methods for assessing toxicity and drug or nutrient absorption. Here, we present an advanced cell culture system able to mimic the dynamic environment of biological barriers while monitoring cell behaviour through real-time impedance measurements and imaging. It consists of a fluidic device with an apical and a basal flow compartment separated by a semi-permeable membrane. The main features of the device are the integration of sensing through transepithelial electrical impedance (TEEI) measurements and transparent windows for optical monitoring within a dual flow system. Caco-2 cells were cultured in the TEEI bioreactor under both flow and static conditions. Although no differences in the expression of peripheral actin and occludin were visible, the cells in dynamic conditions developed higher impedance values at low frequencies, indicative of a higher paracellular electrical impedance with respect to the static cultures. TEEI measurements at high frequency also enabled monitoring monolayer formation, which can be correlated with the observation of an RC behaviour in the impedance spectra. In particular, the cells subject to flow showed accelerated barrier formation and increased vitality with respect to the static controls, again highlighting the importance of dynamic conditions for epithelial cells.

[Changes in various indices of thyroid function in obese adults during diet therapy]. / Modificazioni di alcuni indici di funzionalità tiroidea in adulti obesi durante trattamento dietetico.

Modifications in thyroid function caused by changes in diet have been reported in the literature though the results are often conflicting. The present study was conducted on 48 obese adults divided into two groups: the first over 60% and the second under 60% above their ideal weight. A control group of healthy subjects of normal weight and comparable age was also studied. The observation lasted 9 weeks during which a low calorie diet providing about 1250 kCal was administered. Mean basal levels of FT3, TT3, FT4 and TSH revealed no significant differences between the obese subjects and the control group. Mean TT4 was significantly higher in the obese and mean T3U significantly lower. During low calorie diet treatment the obese subjects produced no significant variations in the above parameters, apart from a significant increase in T3U. The study revealed no evidence of the low T3 syndrome that has long been reported in the literature.