To confirm daily accumulation of visual fatigue induced by work with visual display terminals (VDT), visual evoked potential (VEP), near point distance (NPD) and critical flicker fusion (CFF) were measured in three VDT workers and three sex- and age-matched controls (non-VDT workers) in the morning, noontime and evening for five consecutive days (Monday to Friday), totally 15 times per subject. The workers had been engaged in wireless handling operation, with VDTs, of an unmanned power shovel (Worker 1), an unmanned 78-ton dump truck (Worker 2) and mobile monitor-cameras (Worker 3), for 10 months. Their working hours were about 6.5 hours per day; but, the Worker 2 could take a 10-minute recess (a period without VDT work) per about 30 minutes during working hours. Significant daily variations in the VEP latency, NPD and CFF were found in the Worker 1 or Worker 3 despite the absence of any significant daily or diurnal variations in the non-VDT workers; the trends in the variations were getting worse from Monday to Friday. The NPD in the VDT workers was significantly longer than that in each of the matched controls; also, the CFF in the Workers 1 and 3 was significantly depressed. The changes in the VEP latency from morning to noontime and in the NPD and CFF from noontime to evening were significantly larger in the VDT worker than in the matched control. These findings suggest that VDT work probably affects visual function assessed by the VEP, NPD and CFF. Visual fatigue due to long-term VDT work may tend to be accumulated day by day.
The aim of the present study is to conduct an observation of a time series of job-event/life event and depressive symptoms, prospectively. Ten male computer software engineers were observed every two weeks for five months and every following week for two months. In total, one hundred and eighty-one observations were made. A semi-structured interview was conducted to survey the week-unit job-events on each sampling day. The depressive symptoms were measured using Zung's Self-reporting Depressive Scale (SDS). It was found that the events had a significant effect on the SDS raw score. It also showed that the effective time period of the events on depression is within two weeks. With a week-based analysis in a prospective approach, the present study showed the immediate effects of job events or life events on depressive symptoms.
Fatigue of night duty workers in different divisions of a newspaper office was investigated by physiological methods such as the Blinker, Flicker and grip methods. The relationship between fatigue and hematological parameters such as hemoglobin (Hb), the hematocrit (Ht), serum-free amino acid levels, and indices of liver function such as the GOT and GPT levels were also examined. The composing and press room workers mainly complained of the subjective symptom of muscle fatigue, while workers in the photoengraving and editorial departments mainly complained of mental fatigue. The overall rate of fatigue in the newspaper office was about 38.1%, but varied from one division to another, being especially high in the photo-engraving and editorial departments. The subjects with fatigue had low levels of serum GOT and GPT and high levels of serum-gluconeogenic amino acids, such as aspartic acid, glutamic acid, prolin, glycine, and alanine. These altered levels of serum-free amino acids and GOT and GPT seemed to be due to increased secretion of adrenal corticoid hormone caused by the stress of fatigue.
In this study finger blood pressure was observed by using a new method to determine if vasoconstriction activated by sympathetic nervous system takes part in changes in peripheral circulation with exposure to vibration, noise and tool weight. Finger blood pressure was measured every one minute by ambulatory monitoring system. The time profile of a single experiment consisted of 5 minutes pre-exposure period followed by one exposure period lasting 2 minutes and a post exposure period of 5 minutes. Measurement was carried out as a factorial experiment of combination of vibration (17.8 m/s2 in X-axis, 20.0m/s2 in Y-axis and 50m/s2 in Z-axis), noise (105dBA) and tool weight (7.9kg). Finger blood pressure increased significantly under the following conditions: vibration+noise+tool weight>vibration+noise_??_vibration_??_tool weight>noise_??_ control. During exposure period the combination with vibration, noise and finger grip exercise induced 29.7mmHg of increases on average in finger blood pressure. On the other hand, finger blood pressure was increased 9.5mmHg by vibration alone. These results agreed with our previous studies which observed the decreases of finger skin temperature and finger blood flow during the same conditions. The present study suggests that possible activation of the sympathetic nervous system may be involved in the physiological mechanisms of the changes in blood flow during chain-saw operation.
This study was performed to elucidate the status of the implementation of health promotion programs (HPPs) and future tasks in occupational settings in Japan. A survey was conducted using a multiple type questionnaire mailed to 395 companies throughout Japan in 1993. The questionnaire was mailed back, after having been answered anonymously, with a response rate of 59%. Companies with more than 300 employees accounted for 76% of the sample. Approximately 70% of the companies implemented HPPs of which health guidance and fitness programs were the two most frequently adopted programs. Nutrition education and mental health programs seemed to be emphasized as future possibilities. Smoking cessation programs were not as common as segregation policies, such as zoning of smoking areas. Currently, 45% of the companies used only in-house health personnel for HPPs, but the prospective percentage in the future was 24%. Most of the companies shared the cost of HPPs with a Health Insurance Society. Lack of health personnel and budgetary restrictions on HPPs constituted the major barriers to the implementation of HPPs. Small-scale enterprises were noted to be particularly influenced by these barriers.
We developed a system for exposure of cultured cells to extremely low frequency (ELF) magnetic fields much stronger than those used in previous in vitro studies. The system consists of an electromagnet, a commercial incubator with a custom-designed door and a custom-designed shelf, and other components, and exposes cells in the incubator to ELF magnetic field. We confirmed that it has good performance characteristics in terms of field intensity, field uniformity, waveform, field stability, temperature uniformity, and temperature stability. Its features include: (1) strong ELF magnetic fields (at most, 170 mTRMS), (2) long-term exposure (at least, 5.5h), and (3) variable frequencies (10-100Hz). This exposure system is expected to contribute significantly to research on possible hazards of ELF magnetic fields.
The breakthrough times of five organic solvents at various vapor concentrations were measured in steady-state and pulsating flows on commercially available respirator cartridges. The relationship between the logarithmic vapor concentration and the logarithmic breakthrough time of each organic solvent showed an inverse correlation in both of the flow patterns. The organic solvents with lower boiling points exhibited the shorter breakthrough times in both of the flow patterns. The ratios of the breakthrough times in the pulsating flow to those in the steady-state flow were lower than 0.9 when the vapor concentrations were higher than 600ppm for ethyl acetate, methyl acetate, acetone and dichloromethane. From the present study, the breakthrough in the pulsating flow tends to occur earlier than in the steady-state flow when using a highly concentrated vapor of an organic solvent with a low boiling point.
Circadian rhythms of urinary excretion of corticosterone and catecholamines were examined in the rat before and after phase reversal of a 12-hour light and 12-hour dark cycle. After the reversal, the acrophase of rhythm was delayed and became constant again on the 6th day for corticosterone and on the 7th or 8th day for adrenaline. The ratios of light-period output to 24-hour output of adrenaline and noradrenaline, however, adjusted to the new light-dark cycle on 10th day, whereas this ratio became constant on 6th day for corticosterone. Thus, circadian corticosterone rhythm seems to adapt to light-dark reversal more quickly than catecholamine rhythm.
Repeated exposure of subtoxic doses of mercuric chloride (HgCl2) can induce antinucleolar autoantibodies in susceptible mice. To study the immunopathological mechanism(s), sodium selenite (Na2SeO3), which is known to reduce the toxicity of mercury, is injected simultaneously with HgCl2 into mice. Equimolar Na2SeO3 nor the same amount of Se in Na2SeO3 as Hg in HgCl2 could not reduce antinucleolar autoantibody induction by HgCl2. These results indicate that the mechanism of autoimmunity induction by HgCl2 might be independent of its toxicity.
Two inclusion compounds, progesterone with β- and γ-cyclodextrin, were studied with X-ray powder diffractometry and thermal analysis. Disappearance of characteristic X-ray diffraction patterns of the two compounds as well as the appearance of a new diffraction pattern for each were found when formation of the inclusion compounds was completed. The X-ray diffraction patterns of β-cyclodextrin measured at various temperatures showed a structural change occurring between 60°C to 80°C, which coincided well with the DSC endothermic peak around 75°C. Results suggest that changes in the X-ray diffraction patterns of cyclodextrin during inclusion formation and during heating is due to the displacement of adsorbed water by progesterone in the cavity of cyclodextrin.