Over the past several decades, numerous research studies have performed to establish biological mechanism of stress response, the role of levels of psychological stress and stress-related biomarkers, and the effect of stress relief supplements. However, most stress experiments to date have been focused on acute psychological stress. Increasing attention has been recently given to the evaluation and control/prevention of chronic psychological stress. In this paper, frontiers of psychological stress research in pharmaceutical fields of immunology, cell and molecular biology, biochemistry, and pharmacology are introduced. Neurobiological mechanisms underlying chronic psychological stress and prospective stress-realted biomarkers for chronic stress are reviewed. Furtheremore, particular attention has been briefly given to the saliva collection, stress testing, and data analysis.

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The paper investigated amplitude change of electroencephalogram during performing mental task and listening to unpleasant/pleasant sound in order to evaluate effects of mental work and acoustic environment on brain electrical activity. The amplitude of the alpha wave was decreased by approximately 15∼20% during performing the mental task (mental arithmetic and memorization) and/or listening to acoustic stimuli (5KHz tone and classical music Pachelbel's Canon) in comparing to the amplitude of the alpha wave at rest. Such amplitude suppression corresponds to increase of temporal phase fluctuation of the alpha wave by 15∼30%. In particular, the reduction rate of the amplitude of the alpha wave in the low-frequency range was up to 25% under the combined stresses, namely, the mental arithmetic and unpleasant 5KHz tone, whereas it was limited to 15∼20% during performing the mental arithmetic alone and listening to 5KHz tone alone. On the other hand, the amplitude of the beta and gamma waves showed no significant change under most of stress conditions. The result suggests that the sound and mental stresses suppress the alpha wave in the low frequency range which should be taken into account in the measurement of mental stress.

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To prevent various lifestyle-caused diseases, mental health care in daily life is one of the most important issues in recent years. This paper proposes quantitative analysis method of mental stress using heart rate variability (HRV). Concretely speaking, we proposed the geometric figure analytical method of HRV in consideration for respiration sinus arrhythmia (RSA). Then mental stress is quantitative evaluated by analyzing the characteristic of its plots. Experiments were repeated 51 times on 3 healthy male volunteers. The proposed method was confirmed efficiently, because of the measurement time is about half and the measurement dispersion is decreased in comparison with the conventional analysis methods.

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To investigate the usefulness of salivary α-amylase activity (sAMY) as an index of stress related to invasive medical procedures in children with cancer, we measured sAMY and heart rate (HR) before and after bone marrow aspirations or lumbar punctures in 10 (3 males/7 females, aged 3-15) pediatric cancer inpatients. Observed measurements using Observational Scale of Behavioral Distress (OSBD) and parent and physician reports using Visual Analog Scales (VAS) were also collected to evaluate children's fear and physical distress during the procedure. Relationships between sAMY, HR and other measures were assessed. We found that sAMY immediately after the procedure was significantly related to physicians' ratings of the child's physical distress. We also found that some children whose fear/distress level were low showed high level of sAMY immediately before/after the procedure. Our findings suggest that sAMY reflected children's mental and physical stress sensitively, and can be a useful index of stress related to invasive medical procedures in children with cancer.

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In order to develop an evaluating method of photo-stress of skin, we have been investigating a methodology to analyse catalase activity derived from stratum corneum (skin catalase activity) as a biomarker. The objective is to demonstrate the usefulness of skin catalase activity as an index of photo-stress by compairing the cheek and the upper arm in 61 female adults. The stratum corneum was collected by tape stripping, concentrating stratum corneum sample solution and using a fluorescent substrate of skin catalase activity. The skin catalase activity ranged between 1.18 and 223 U/cm² in all of the stratum corneum samples in the subjective evaluation. It was indicated that this analysis method had a sufficient range for the analysis of skin catalase activity. The significant correlation was observed between the skin catalase activity /total protein (TP) ratio and the skin color parameter (skin color: a^*, r =0.54; b^*, r = -0.44). Therefore, it was considered that the skin catalase activity /TP ratio might be a useful index of the skin condition for humans.

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The construction of a system for analysis of cell population behavior during real-time monitoring is anticipated to evaluate normal cellular function noninvasively and quantitatively on scaffolds. This report presents the construction of a cell visualization system in real-time and reports measurement of cellular singular nature on the scaffolds. Two types of segmented polyurethane (SPU) scaffolds, including nanofiber (0.76±0.12 μm) and microfiber (5.79±0.46 μm) scaffolds with fiber orientation were fabricated using an electrospinning method. Mouse fibroblasts (NIH3T3) were seeded to SPU fibrous scaffolds in a culture well. The relations of the scaffold structure to the direction and migration speed of the cell population were investigated to analyze cell population behavior over the period of a week using particle image velocimetry (PIV) in real-time. The PIV analysis results demonstrated the ability to perform vector analysis at the same time for plural numbers of cells. The migration of individual cells in the population was analyzed using fibers designed with a diameter of 0.76±0.12 to 5.79±0.46 μm. Individual cells in the cell population migrated approximately 30 μm/h on the fibrous scaffolds. In conclusion, the system developed using PIV was effective for the analysis of cell population behavior.

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