Toru Itani

Antihypertensive effect of ACE inhibitory oligopeptides from chicken egg yolks.

Oligopeptides of 1 KDa or less were obtained by hydrolysis of chicken egg yolks with a crude enzyme, and by dialysis with a semipermeable membrane filter. Since the extracted peptides had an inhibitory action on the activity of angiotensin I-converting enzyme (ACE) in vitro, they were orally administered at 20, 100 and 500 mg/kg body weight to spontaneously hypertensive rats (SHR) for 12 weeks to analyze the physiological role on cardiovascular functions. The administered oligopeptides suppressed the development of hypertension at all dosages. After 12 weeks at 500 mg/kg body weight, the values for systolic, mean, and diastolic blood pressure were approximately 10% less in SHRs administered than controls. Furthermore, serum ACE activity of the peptide-administered groups was significantly lower than that of the control group in a dose-related manner. Our results imply that oligopeptides extracted from hens egg yolks could potentially suppress the development of hypertension in SHR, and this effect might be induced by the inhibition of ACE activity.

Urinary 1-hydroxypyrene levels of garbage collectors with low-level exposure to polycyclic aromatic hydrocarbons

Because garbage collectors work in the street, they are exposed to polycyclic aromatic hydrocarbons (PAHs) in motor vehicle exhaust gas as they work. Urinary 1-hydroxypyrene (1-OH-pyrene) began to be used as a biological monitoring index for human exposure to high concentrations of PAHs. The objective of this study was to examine the applicability of urinary 1-OH-pyrene as a biological monitoring index for human low-level PAH exposure, such as the PAH exposure experienced while working in the street. The subjects were fifteen male garbage collectors. We measured individual exposure to PAHs, urinary 1-OH-pyrene concentrations and urinary cotinine concentrations. Individual air samplers were attached to the collar of the clothing of five workers to capture PAHs. Urine samples were collected before work, around noon and after finishing the days work. In all, five PAH samples and 45 urine samples were collected. As control data, we analyzed the urinary 1-OH-pyrene and urinary cotinine levels of six smoking and four non-smoking control subjects who were not occupationally exposed to PAHs. The benzo[a]pyrene level in the air sampled for 5-6 h was 2.5-10.5 ng/m3, and the pyrene level as 10.3-70.3 ng/m3. These levels were similar to those in the vicinity of streets in Japan. A positive correlation between total PAH levels and the pyrene levels was observed. The average urinary 1-OH-pyrene level of the smokers was 0.21 +/- 0.13 mumol/mol creatinine, vs. 0.15 +/- 0.11 mumol/mol creatinine in the non-smokers. The urinary 1-OH-pyrene level obtained in this study was slightly higher than in the control group. No correlation was found between pyrene exposure and the urinary 1-OH-pyrene level of the five workers who wore the personal samplers. A significant positive correlation was observed between the urinary 1-OH-pyrene level and urinary cotinine level of the smokers. A significant positive correlation was also observed between the urinary 1-OH-pyrene and urinary cotinine levels of the control group smokers. In conclusion, urinary 1-OH-pyrene is not applicable for biological monitoring of extremely low levels of exposure to PAHs, as in the case of working in the street. Caution is required to exclude the effects of smoking when evaluating PAH exposure.

Low-cost work improvements that can reduce the risk of musculoskeletal disorders

Abstract Types of low-cost improvements that could reduce work-related musculoskeletal disorders were reviewed by examining simple improvements in materials handling and workstations undertaken within a Work Improvement in Small Enterprises (WISE) project in the Philippines. Serial WISE action-training courses in four regions of the Philippines yielded many improvements relying on local resources. Over 2000 improvements resulted from participatory activities in small groups, and many of them were found to relate to actual reduction of musculoskeletal loads. Typically, these improvements, mostly implemented at low cost during the course period of about 2 weeks, concerned the use of push carts or lifting devices, better worksite layout, worktables and chairs of appropriate height, fixing handtools, better lighting, job rotation and inserting breaks. The effects of such improvements on reducing workloads were investigated by case study measurements applying electromyography, heart rate recording and posture study methods. Reduced muscular activities were found after work changes associated with improved materials transport, avoiding deep bending postures, fixing handtools or better work organization. Productivity increase was also confirmed in some cases. There was thus a variety of work improvements undertaken by managers and workers of small enterprises through voluntary training steps, often with combined effects on reducing musculoskeletal loads and improving other aspects of working conditions. This flexibility in work re-design seemed necessary in promoting multiple changes linked with a reduced musculoskeletal risk. Such examples collected from WISE training courses proved useful for various training programmes and advisory inspections. These results demonstrated the importance of undertaking multiple work improvements on voluntary basis in reducing the risk of musculoskeletal disorders in a large number of small enterprises. Relevance to industry There is a perception in industry that improvements to reduce the risk of musculoskeletal disorders are too costly. This paper demonstrates that a participatory approach can be successful in making work improvements with very little cost. Further, the work improvements reduced the risk of musculoskeletal disorder and increase productivity.

Effects of shift schedules on fatigue and physiological functions among firefighters during night duty.

To examine the effects of shift schedules on fatigue and physiological functions among firefighters a 17-day field study at a fire station was carried out. Eleven firefighters, who were engaged in firefighting emergency services, participated in this study. At the fire station, night duty (22:00–07:00) was divided into 5 periods (P1: 22:00–00:00; P2: 23:45–01:45; P3: 01:30–03:30; P4: 03:15–05:15; P5:0 5:00–07:00). The participants were assigned to one of these 5 periods and awakened to answer calls from the citys central information centre. They took naps in individual rooms during night duty, except when on night shift or when called out on an emergency. Subjective complaints of fatigue, critical flicker fusion frequencies, 3-choice reaction times, and oral temperature were measured before and after work and following breaks during their 24 working hours. Heart rate variability was also recorded to evaluate autonomic nerve activity. The results show that during P3 and P4, participants who had to wake up at midnight took shorter naps. The rates of subjective complaints regarding P3 and P4 tended to be higher than those for P1, P2, and P5. The ratios of the low frequency component of heart rate variability to the high frequency component during P4 were significantly lower than those during P5. It is assumed that such an irregular sleeping pattern causes many complaints of subjective fatigue, and adversely affects physiological functions. A night-duty shift schedule ensuring undisturbed naps should be considered.

Effects of the length and timing of nighttime naps on task performance and physiological function

OBJECTIVE To examine the effects of the length and timing of nighttime naps on performance and physiological functions, an experimental study was carried out under simulated night shift schedules. METHODS Six students were recruited for this study that was composed of 5 experiments. Each experiment involved 3 consecutive days with one night shift (22:00-8:00) followed by daytime sleep and night sleep. The experiments had 5 conditions in which the length and timing of naps were manipulated: 0:00-1:00 (E60), 0:00-2:00 (E120), 4:00-5:00 (L60), 4:00-6:00 (L120), and no nap (No-nap). During the night shifts, participants underwent performance tests. A questionnaire on subjective fatigue and a critical flicker fusion frequency test were administered after the performance tests. Heart rate variability and rectal temperature were recorded continuously during the experiments. Polysomnography was also recorded during the nap. RESULTS Sleep latency was shorter and sleep efficiency was higher in the nap in L60 and L120 than that in E60 and E120. Slow wave sleep in the naps in E120 and L120 was longer than that in E60 and L60. The mean reaction time in L60 became longer after the nap, and faster in E60 and E120. Earlier naps serve to counteract the decrement in performance and physiological functions during night shifts. Performance was somewhat improved by taking a 2-hour nap later in the shift, but deteriorated after a one-hour nap. CONCLUSIONS Naps in the latter half of the night shift were superior to earlier naps in terms of sleep quality. However performance declined after a 1-hour nap taken later in the night shift due to sleep inertia. This study suggests that appropriate timing of a short nap must be carefully considered, such as a 60-min nap during the night shift.

Effects of a Modified Ambulance Night Shift System on Fatigue and Physiological Function among Ambulance Paramedics

Effects of a Modified Ambulance Night Shift System on Fatigue and Physiological Function among Ambulance Paramedics: Hidemaro Takeyama, et al. Faculty of Human Wellness, Department of Registered Dietitians, Tokaigakuen University

Interactive Model of Subsidiary Behaviors, Work Performance and Autonomic Nerve Activity during Visual Display Terminal Work

Interactive Model of Subsidiary Behaviors, Work Performance and Autonomic Nerve Activity during Visual Display Terminal Work: Toshimasa Takanishi, et al. Department of Occupational and Environmental Health, Nagoya City University Graduate School of Medical Sciences

Estimation of Energy Expenditure during Sedentary Work with Upper Limb Movement

Estimation of Energy Expenditure during Sedentary Work with Upper Limb Movement: Kunio Tsurumi, et al. Health Sciences of Life, Work and Environment, Department of Environmental Health Science and Health Promotion, Graduate School of Medical Sciences, Nagoya City University—This study aims to evaluate the availability of surface‐ electrode electromyogram (EMG) and acceleration to predict energy expenditure during sedentary work with upper limb movement. The following variables were measured in 12 female subjects: oxygen consumption (VO2), heart rate, EMG from the medial and anterior part of the deltoid muscle, and acceleration of wrist movement. The subjects were requested to perform four different sedentary tasks. In tasks 1, 2 and 3, subjects touched two points on a table (height 70 cm) alternatively. The distance between the two points was 50 cm in tasks 1 and 3, and 100 cm in task 2. The frequency of the movement was 100 touches per minute in tasks 1 and 2, and 152 touches in task 3. In task 4, the points were located vertically on a wall, so they had to move their upper limb vertically in this task. The height of the points was 10 cm below and 40 cm above the acromion height of the subject, and task frequency was 100 touches per minute. The correlation coefficient was 0.285, 0.581 and 0.676, between VO2 and heart rates, VO2 and acceleration, and VO2 and EMG from the deltoid, respectively. The coefficient of determination was 0.648, when employing multiple regression analysis, with acceleration and EMG as independent variables. These results suggest that energy expenditure during sedentary work with upper limb movement can be well estimated by using the data from acceleration of wrist movement and the EMG of the deltoid.

Psycho-Physiological Effects of Naps during Night Shifts on Morning Types and Evening Types

Psycho‐Physiological Effects of Naps during Night Shifts on Morning Types and Evening Types: Hidemaro Takeyama, et al. Department of Hygiene and Occupational Health, Nagoya City University, Medical School—An experimental study was carried out under simulated shift‐work schedules to examine the effects of a nighttime nap on task performances and psycho‐physiological functions on morningness (M‐types) and eveningness (E‐types) subjects. Sixty male students, classified as M‐types or E‐types by the Japanese version morningness‐eveningness questionnaire, were recruited for this study. Five moderate M‐types and eight moderate E‐types were selected. Their MEQ scores were 32‐41 (average 36.9) in E‐types and 60‐64 (average 62.4) in M‐types, respectively. Experiment periods were simulated shift schedules of 9 consecutive days consisting of 2 d shifts (working 8:00‐16:00), 3 night shifts (working 22:00‐8:00) and 3 d shifts. They carried out two series of experiments. In one series the subjects took a nap from 2:00 to 4:00. In the other series they did not take a nap during the night shift. In order to minimize the effect of the previous experiments, a rest period of more than one week was inserted between the nap‐condition and the no‐nap condition experiments. During the shifts, the subjects repeatedly performed two kinds of tasks: typing figures listed randomly on sheets into a computer for 20 min; and after a 5 min break performing mental arithmetic with two adjacent figures, listed randomly on the sheets, for 15 min. During the breaks, psycho‐physiological functions and questionnaires on subjective feelings of fatigue and index of the state of anxiety were examined. Throughout the experiments, heart rate variability was also recorded with a portable recorder to evaluate autonomic nerve activity. Task performances decreased and subjective feelings of fatigue and anxiety scores increased in proportion to the length of time worked in both M‐types and E‐types who had no nap. In M‐types, these changes were significantly suppressed by the nap on the first night of duty. Parasympathetic nerve activity for M‐types estimated from heart rate variability between 4:00 and 6:00 under nap conditions decreased significantly compared with that under no‐nap conditions. Overall changes for E‐types, however, were smaller than those for M‐types in terms of task performance and psycho‐physiological parameters. The present study suggested that taking a nighttime nap was an effective way to reduce adverse effects due to first nocturnal work, especially for M‐types.