A large ocular surface area (OSA) is thought to be one of the causes of eye irritation and eye fatigue. Because ocular surface is very sensitive to various irritants such as dust, heat, dryness, air flow, etc., a large OSA increases the possibility of eye surface exposure to such irritants. Thus, OSA is one of the most important indices of visual ergonomics. This paper aims at making OSA an exact and practical index by first describing an accurate method of measuring it, and then clarifying the relationship between OSA, the width of the palpebral fissure, and vertical gaze direction, all of which are thought to be strongly correlated with each other. We derived the following equations: 1) y=0.039x1+3.36, r=0.99, 2) y=3.05x2-0.39, r=0.97, 3) x1=72.7x2-91.4, r=0.97, where x1=vertical gaze direction (degrees), x2=width of the palpebral fissure (cm), y=OSA (cm2). Finally, this paper also introduces the practical applications of OSA measurement, and notes the differences between OSA when VDT work (word processing using a keyboard and drawing a picture using a mouse) is performed and when traditional office work without a VDT (reading, drawing, and writing) is performed.
To clarify the time course of circadian rhythm adaptation to a phase shift of the light-dark (LD) cycle, urinary excretion of catecholamines was measured in rats before and after a 12-hour or 6-hour phase delay of a 12-hour light and 12-hour dark schedule. In rats under a basal condition, distinct circadian rhythms in catecholamine excretion were observed, especially in adrenaline excretion. During the 1st and 2nd days after a 12-hour phase delay, the acrophase and amplitude of adrenaline rhythm remained almost unchanged, but thereafter the acrophase was retarded and the amplitude was reduced. The acrophase once again became constant after 5 or 6 days, but the ratio of amplitude to mesor in the circadian rhythm of adrenaline excretion and the ratio of light-period to 24-hour noradrenaline excretion were readjusted to the new LD schedule on 11th or 12th day. In the 6-hour phase delay of the LD cycle, similar findings were observed, and the results suggested adaptation on the 5-6th day. It is considered that the circadian rhythms of the sympathetic adrenomedullary function are restored, at the latest, 12 days after a 12-hour delay of the LD cycle, and 6 days after a 6-hour delay, suggesting that rats need approximately 1 day to adapt to a 1-hour phase shift.
We conducted a prospective study to clarify mortality patterns among Japanese coal miners in a former coal mining area. Subjects included 1, 796 coal miners and 4, 022 non-coal-miners, who were identified by a mail survey between 1987 and 1989, and then followed up from the date of the survey to April 30th, 1994. We applied Cox's proportional hazards model to compare the mortalities between coal miners and non-coal-miners. Among the coal miners, significantly high risk ratios were observed in all causes of death (risk ratio = 1.4, p < 0.05) and all malignant neoplasms (risk ratio = 1.5, p < 0.05). Risk ratios for all causes of death and all malignant neoplasms also rose with the length of experience in coal mining. Analysis of the results for sites of cancer showed that coal miners had high risk ratios for stomach cancer (risk ratio = 1.6), liver cancer (risk ratio = 1.4) and lung cancer (risk ratio = 1.6), though these ratios were not statistically significant. When the risk ratio for lung cancer was analyzed according to the length of experience in coal mining, coal miners with at least 15 years' experience had a significantly high risk ratio (risk ratio = 2.4, p < 0.05), though coal miners with less than 15 years' experience had almost the same risk as non-coal-miners.
To investigate the effects of marital status and position on DSM-III-R personality traits, we administered the self-rating questionnaires of the Structured Clinical Interview for DSM-III-R Personality Disorders to 757 male computer engineers, aged 20 to 49 years, at a computer manufacturing plant. The scores for six of eleven personality traits were significantly higher in single computer engineers than in married ones. Also, among the engineers aged 40 to 49, the scores for six personality traits of section-heads were significantly higher than those among persons in the other positions. These findings suggest that“maladaptive”personality traits, defined by the DSM-III-R, differ with marital status and position in a company.
Efficacy of Triethylenetetramine hexaacetic acid (TTHA) encapsulated in liposomes having different lipid compositions was examined in animals pre-exposed to cadmium. Mice were injected with cadmium as cadmium (II) chloride 0.5mg/kg b. wt. intraperitoneally daily for five days. Four weeks after the last injection of cadmium they were administered three injections of TTHA encapsulated in liposomes composed of either phosphatidyl choline:cholesterol (PC:Chol) or sphingomyelin:cholesterol (SM:Chol) in 1:1 molar ratio at a gap of 48h. Urinary and fecal elimination of cadmium and its distribution in liver, kidneys and spleen were examined. Treatment with TTHA encapsulated in liposomes mobilized higher amount of cadmium from liver and spleen. The overall efficiency for cadmium mobilization was better in TTHA encapsulated in SM:Chol liposome treated group which also led to enhanced excretion of cadmium through urine and feces. The results indicate that TTHA encapsulated in SM:Chol liposomes exhibited highest efficacy in mobilizing cadmium from the body of pre-exposed mice followed by PC:Chol liposomes and the free drug.