Masato Suzuki

ABSTRACT We developed a novel electrorotation (ROT) device featuring a microwell array with three electrodes. This device allows to monitor the increase in membrane capacitance of cells subjected to chemical stimulation. The microwell array is integrated into the bottom of a fluidic channel and holds rotating cells during stimulation with a solution containing a chemical agent. Positive dielectrophoresis (p‐DEP) effectively traps cells in microwells, whereas negative DEP (n‐DEP) facilitates the rapid formation of single‐cell presence. Alternating current (AC) voltages with a 120° phase shift applied across the three electrodes enable vertical and simultaneous rotation of cells. We observed a peak in rotation rate as a function of applied frequency, with the frequency spectrum shifting to lower frequencies as membrane capacitance increased. A positive correlation was identified between rotation rate and membrane capacitance, so monitoring in the low‐frequency range is advantageous. Although n‐DEP at lower frequencies risks removing cells from microwells, the continuous monitoring of the ROT rate during chemical stimulation was achieved by regulating the height of the ROT center of cells. We demonstrated the monitoring of membrane capacitance increase induced by Ca²⁺ influx from ionomycin. This simple configuration facilitates statistical analysis of ROT rates without fluorescent labeling, making it suitable for label‐free assessments of white blood cells’ responses to stimuli.

Many sexually mature women experience premenstrual syndrome (PMS) or premenstrual dysphoric mood disorder (PMDD). Current approaches for managing PMS and PMDD rely on daily mental condition recording, which many discontinue due to its impracticality. Hence, there's a critical need for a simple, objective method to monitor mental symptoms. One of the principal symptoms of PMDD is a dysfunction in emotional regulation, which has been demonstrated through brain-function imaging measurements to involve hyperactivity in the amygdala and a decrease in functionality in the prefrontal cortex (PFC). However, most research has been focused on PMDD, leaving a gap in understanding of PMS. Near-infrared spectroscopy (NIRS) measures brain activity by spectroscopically determining the amount of hemoglobin in the blood vessels. This study aimed to characterize the emotional regulation function in PMS. We measured brain activity in the PFC region using NIRS when participants were presented with emotion-inducing pictures. Furthermore, moods highly associated with emotions were assessed through questionnaires. Forty-six participants were categorized into non-PMS, PMS, and PMDD groups based on the gynecologist's diagnosis. POMS2 scores revealed higher negative mood and lower positive mood in the follicular phase for the PMS group, while the PMDD group exhibited heightened negative mood during the luteal phase. NIRS results showed reduced emotional expression in the PMS group during both phases, while no significant differences were observed in the PMDD group compared to non-PMS. It was found that there are differences in the distribution of mood during the luteal and follicular phase and in cerebral blood flow responses to emotional stimuli between PMS and PMDD. These findings suggest the potential for providing individuals with awareness of PMS or PMDD through scores on the POMS2 and NIRS measurements.

Many sexually mature females suffer from premenstrual syndrome (PMS), but effective coping methods for PMS are limited due to the complexity of symptoms and unclear pathogenesis. Awareness has shown promise in alleviating PMS symptoms but faces challenges in long-term recording and consistency. Our research goal is to establish a convenient and simple method to make individual female aware of their own psychological, and autonomic conditions. In previous research, we demonstrated that participants could be classified into non-PMS and PMS groups based on mood scores obtained during the follicular phase. However, the properties of neurophysiological activity in the participants classified by mood scores have not been elucidated. This study aimed to classify participants based on their scores on a mood questionnaire during the follicular phase and to evaluate their autonomic nervous system (ANS) activity using a simple device that measures pulse waves from the earlobe. Participants were grouped into Cluster I (high positive mood) and Cluster II (low mood). Cluster II participants showed reduced parasympathetic nervous system activity from the follicular to the menstrual phase, indicating potential PMS symptoms. The study demonstrates the feasibility of using mood scores to classify individuals into PMS and non-PMS groups and monitor ANS changes across menstrual phases. Despite limitations such as sample size and device variability, the findings highlight a promising avenue for convenient PMS self-monitoring.