In human cervical cells, extracellular ATP induces an acute decrease in the resistance of the lateral intercellular space, the phase I response, followed by a delayed increase in tight junctional resistance, the phase II response. These responses depend on vitamin A because incubation of cells in retinoid-free medium (RFM) abolished both responses. Treatment with retinoic acid restored the phas...

Solid phase extraction (SPE) or liquid-solid extraction is poplar and growing techniques that areused to sample preparation for analysis. Metal nanoparticles have been studied for decades, and this is due to the properties that these materials do not have in bulk state. In nanoscale materials, the numbers of surface atoms is high and hence, have significant surface effects. A novel, simpl...