Mechanical stimulation plays an important role in a regulation of cellular functions. However, cellular dynamics induced by various mechanical stimuli are not fully understood. In order to understand cellular responses depending on loading parameters of mechanical stimuli, impulsive force induced by a focused femtosecond laser pulse in water was applied. In this paper, cytosolic Ca2+ signaling stimulated by the femtosecond laser impulse are presented. We discuss signaling pathway of the cytosolic Ca2+ increase induced by the impulse and modifications of the Ca2+ signaling from viewpoints of loading parameters of the impulse and cellular physiological states. As a result, we conclude that laser induced impulse is a promising tool to investigate single cellular responses to mechanical stimuli.

Electrogastrography (EGG) is a noninvasive and affordable measurement technique that measured myoelectric activity of the stomach using a surface electrode placed on the skin of the abdomen. Gastric myoelectrical activity consists of Electrical Control Activity (ECA) and Electrical Response Activity (ERA). Although ERA could be responsible for some changes in EGG signals, it is not widely implemented in EGG analysis. The main reasons are very low amplitude compared with ECA, lack of standardization of frequency band, and complex signal classification. We proposed a methodology that could provide sufficient information for ERA using three-channel EGG with less recording time. Recordings from the three anatomical landmarks in 10 healthy subjects were compared under two conditions, fasting and postprandial by evaluating the ERA band power. Our results showed that there is a statistically significant increase of ERA band power in postprandial period (p<0.01) in each of the three channels.

Uroflowmetry is necessary for patients with voiding disturbance. It is desirable to achieve uroflowmetry in a natural position in a familiar environment. We developed a uroflowmeter based on weight loss during standing urination. In the previous research, the system employed a PC for the measurement. However, there were problems of portability and installation in the feasibility study. In this study, we developed a system that wirelessly connects the weight scale to a small microcomputer and records weight changes. To evaluate the developed system, pseudo-urination was performed with a urine flow rate in the range of 5-50 ml/s. Resulting showed that urinary flow patterns measured by this system follow that measured by a medical uroflowmeter. The maximum urinary flow rate measured by this system agreed with that measured by the medical uroflowmeter within 10% error. This study was supported in part by JSPS KAKENHI Grant Number JP19K09667, Japan.