A mathematical model for the micro-dynamics of cultured cells measured with the ECIS (Electrical Cell-substrate Impedance Sensing) system that can separately evaluate the cell-to-cell distance and the cell-to-substrate distance is proposed. For wide applications of this method, mathematical models considering various types of cells and confluent conditions were constructed. Using ECIS TM, frequency the characteristics of 25 Hz to 60 kHz of impedance of HUVEC (human umbilical vein endothelial cells), BAEC (bovine aortic endothelial cells), in the pre-confluent condition and the full confluent condition of each cell were measured. A mathematical model of the micro-dynamics of the cultured cells measured with ECIS from 1 kHz to 10 kHz, which was the most interesting frequency range for the micro-dynamic analysis in the ECIS methods is proposed. The evaluation method of the cell-to-cell distance (A) and the cell-to-substrate distance (h) could be improved. In the application, we investigated the effect of the X-ray radiation exposure from 1 Gy to 100 Gy on the cultured cells BAEC using the ECIS system. Impedance changes could be confirmed by exposure to 100 Gy. The X-ray stimulation of 100 Gy resulted in a significant increase of the value of the cell-to-cell distance (A).
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Swallowing disorders are a serious problem occurring in association with cerebrovascular disorder, nerve or muscle disease, laryngeal or esophageal disease, or advanced age. Unfortunately, it is difficult to evaluate swallowing disorders quantitatively. For this reason, we previously proposed a new method, impedance pharyngography (IPG), for evaluating swallowing disorders noninvasively by measuring neck electrical impedance during swallowing. In this study, the efficacy of this method was tested in a cohort of patients with IPG and healthy controls. The change of neck electrical impedance in the pharyngeal phase is mainly caused by the changes in the equivalent cross-sectional area of the near epiglottis. In addition, the increase in equivalent cross-sectional area due to raising of the larynx caused a decrease in neck electrical impedance in the pharyngeal phase. In the case of healthy subjects, IPG results were highly reproducible, and the patterns were simple and similar. In subjects with advanced age, IPG are delayed-action, slowly changing and less reproducible, and showed various patterns among the subjects. In subjects with swallowing disorders, IPG results were less reproducible and showed irregular variable patterns. We therefore conclude that the IPG pattern can be used effectively as a simple index of swallowing activity.
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