Kosuke Oiwa

Functional innervation of human induced pluripotent stem cell-derived cardiomyocytes by co-culture with sympathetic neurons developed using a microtunnel technique

Microelectrode array (MEA) based-drug screening with human induced pluripotent stem cell-derived cardiomyocytes (hiPSCM) is a potent pre-clinical assay for efficiently assessing proarrhythmic risks in new candidates. Furthermore, predicting sympathetic modulation of the proarrhythmic side-effects is an important issue. Although we have previously developed an MEA-based co-culture system of rat primary cardiomyocyte and sympathetic neurons (rSNs), it is unclear if this co-culture approach is applicable to develop and investigate sympathetic innervation of hiPSCMs. In this study, we developed a co-culture of rSNs and hiPSCMs on MEA substrate, and assessed functional connections. The inter-beat interval of hiPSCM was significantly shortened by stimulation in SNs depending on frequency and pulse number, indicating functional connections between rSNs and hiPSCM and the dependency of chronotropic effects on rSN activity pattern. These results suggest that our co-culture approach can evaluate sympathetic effects on hiPSCMs and would be a useful tool for assessing sympathetic modulated-cardiotoxicity in human cardiac tissue.

Contactless blood pressure sensing using facial visible and thermal images

Hypertension is one of the leading risk factors for several diseases. Measurement and monitoring of blood pressure anytime and anywhere are important to lower blood pressure and prevent pathogenesis of diseases. Non-contact blood pressure measurement is desired to monitor blood pressure anytime and anywhere. The aim of this study was to develop a non-contact blood pressure sensing system. A previous study reported that amplitude and time differences of facial photoplethysmogram (PPG) components extracted using brightness variation of facial skin color in facial visible images could be useful indices for estimating blood pressure. The maximum error between measured and estimated blood pressure using facial PPG components was 12 mmHg. An additional signal processing algorithm is desired to increase the accuracy for estimating blood pressure using facial PPG components. By contrast, facial skin temperature also reflects changes in the facial blood circulation. High-accuracy estimation of blood pressure could be expected using both facial PPG components and facial skin temperature. In this study, improvement of accuracy for estimating blood pressure using facial PPG components by attempting to apply additional signal processing to facial skin color variation. Furthermore, a correlation analysis between facial skin temperature and measured blood pressure was performed, and individual models for blood pressure estimation were created.

Psychophysiological assessment of an adaptive asynchronous human---machine system with the dual-task method

Human error is one of the leading causes of industrial accidents at modern manufacturing production sites. An adaptive asynchronous human–machine system (Async-HMS) was previously proposed as a new mechanism for preventing the reduction of cognitive level by controlling the actual operation period of machines that lead to monotonous behavior. The objective of this paper is to assess Async-HMS from the aspects of person’s current capacity for performing processing resources. A dual-task method consisting of a synchronization task with three periodic fluctuations and four levels of difficulties of mental arithmetic tasks was conducted with Async-HMS on a PC. The three periodic fluctuations are constant periodic fluctuation (Cnst), perceptible periodic fluctuation (Supraliminal), and imperceptible periodic fluctuation (Subliminal). The task performance and the psychophysiological state were assessed through the dual-task method. In an ANOVA analysis, the time shared fraction, which is an index of processing resources devoted to an arithmetic task, had no significant effect on the synchronization task. The mean blood pressure in Subliminal had a significant increase compared with that in Cnst and Supraliminal. These results indicate that subliminal fluctuation evokes sympathetic hyperactivity without affecting processing resources. Implementation of subliminal operation period into industrial machines performing periodic behavior might inhibit monotony and, therefore, prevent human error.