The present study was designed to examine a relation between evoked GSR at the cases of signal presentation and signal detection or detection performance in a visual (experiment 1) and an auditory (experiment 2) vigilance task. In experiment 1 two tasks lasting for 30 min without (task A) and with (task B) monitoring the outer response to the signal were carried out on 10 healthy young men. The experi- ment 2 which was performed by another 10 subjects was the same as the experiment 1 except that auditory signals were used. It was found that the GSR did not always occur at the cases of signal detection with monitoring the outer response to the signal in both experiments 1 and 2. It was also found that signal presentation accompanied by GSR during the task B was high as compared with that during the task A in both experiments 1 and 2. Although there was no significant correlation between signal presentation accompanied by GSRduring the task A and detection performance during the task B in both experiments 1 and 2, a statistical correlation between the signal presentation or signal detection accompanied by GSR during the task B and the detection performance during the task B in the experiment 2 was significant. From the results observed in the auditory vigilance task, it seems likely that detection performance is roughly evaluated by signal presentation or signal detection accompanied by GSR.
Influence of unpleasant feeling toward task performance on the stress response of healthy young male subjects at two sorts of mental tasks was investigated. A simple calculation task assigned to 10 subjects for 8 hr a day using a new signal indicator was accompanied by increase in serum protein level and decrease in pulse rate, systolic blood pressure, pulse pressure and serum A/G in the morning, but not in the afternoon. Unpleasantness rate during this task performance had converse correlation with the serum level of proteins in the morning but not in the afternoon. "Addition-subtraction task" of two figures assigned to 20 subjects for 1 hr at the task density of 80% of individual maximum performance using a signal indicator evidently induced the stress response such as increases in pulse rate, diastolic blood pressure and the serum level of proteins, and decrease in the serum water content. In this case, there was no correlation between the physiological stress indices and unpleasantness rate in task performance. Moreover, neither the stress response nor the unpleasant feeling had relation to physical fitness of the subjects. It was deduced that the stress response during mental tasks was hardly influenced by unpleasant feeling toward task performance or by physical fitness of subjects.
It is said that absenteeism is a complicated phenomenon, and that it includes not only health matters but subtle workmen's incentive. The author believes, how-ever, that factors by which absenteeism is influenced are not too complicated. The author wishes to discuss kernel composition of dynamics of absence is rather simple, and a record of absenteeism might be used as one of the basic information sources concerning workmen's health. This paper presents the results of factor analysis on sickness absenteeism and adds some information about the significance of absenteeism. The amount of absence largely depends on age composition of workers, work system, sexual ratio of workers, kinds of sick benefit plan available, etc. As a matter of fact, if these conditions are equally observed in two factories, a level of absence of the one would likely to show the same of the other. When those conditions are known in some factory, it would be able to estimate a level of absence in that factory with certain reliability. And when absence level has arisen, or some change in absence record is observed, it could be checked whether or not some unusual conditions have affected employees. It has already been discussed in terms of the interpretation of individual factors, there were no substantial differences due to sexual difference. It was found some features seemed to represent the characteristics in the dynamics of absent phenomena in each sex.
A rapid, inexpensive and simple method using Tetrahymena pyriformis has been established for the biological study on heavy metal toxicity. The growth of this organism was highly sensitive to various kinds of heavy metals and was affected at the concentration of 10-6 M of the metals. The strength of the toxicity was clearly expressed by the protein concentration of the cultured Tetrahymena pyriformis in medium containing the varying concentration of the metal. Cadmium and mercury inhibited most remarkably the growth of Tetrahymena pyriformis and the complete inhibition was observed at the concentration of 4×10-6 M, while selenium, manganese, zinc and copper showed less toxic effects, and magnesium and calcium had no notable effect on the organism. Zinc administered simultaneously with cadmium reversed the inhibitory effect of cadmium. On the other hand, mercury and cadmium additively inhibited the growth of the organism. It should be noted that the newly established method detects not only toxicity of heavy metals, but also the mutual effect of two kinds of metal com-pounds on organisms.
In vitro effect of various heavy metals on activity of α-mannosidase, which has been regarded as a zinc-enzyme, was investigated after purifying the enzyme from the liver and epididymis of healthy mice. Unexpectedly, cadmium enhanced the enzyme activity at the concentrations from 10-5 to 10-3M, and both zinc and EDTA reversed the enhancement of the enzyme activity by cadmium maximally at the same concentration as cadmium. Zinc alone slightly activated the enzyme through the tested concentrations (10-6-10-4M), and copper showed the similar enhancement of the activity to that by cad-mium, though the degree of the enhancement was not so great as compared with cadmium.These findings indicate that zinc and cadmium oppose each other on the activity of α-mannosidase obtained from the liver and epididymis of mice, and that the enzyme might not have zinc as an essential component.
The effect of administration of cadmium was investigated on the changes of the contents of sulfhydryl (SH) group and of protein in various tissues of mice after development of a simple method for the determination of SH group. A slight increase of SH group per unit weight of kidney was observed in the supernatant of homogenate which was obtained from mice exposed to cadmium as compared with the level of control. The increased value in the content of SH group was magnified when the proteinsof kidneys of both mice groups were fractionated by alcohol-chloroform and zinc fractionation method. When the mice were bred for seven months with a drinking water containing 0.8mM cadmium acetate, about 7 fold increase in the content of SH group and 4 fold increase in the specific SH group value were observed in this final fraction. It was concluded that the determination of SH group, especially by the simple method, would be a reliable biochemical parameter for cadmium exposure.
Rabbits were injected intratracheally manganese dioxide (400 mg/kg). Serum calcium, inorganic phosphates and alkaline phosphatase levels were determined at the interval of 60 days over a period of 240 days. Simultaneously histological studies were carried out in parathyroids, bones and kidneys. A significant decrease in the levels of serum alkaline phosphatase, inorganic phosphates and an increase in calcium was noted at 180 days. These biochemical alterations occured at a much earlier stage than the development of symptoms of manganese encephalopathy which are of great significance to detect early toxicity.
Eight and 24 hr after the single inhalation of the vapor, CCl4 deposited mostly in the adipose tissue in the rats. Carbon tetrachloride disappeared from the tissue very rapidly leaving less than one twentieth of 2 hr value at 48 hr. Groups of rats were exposed to 10, 50 and 100 ppm of CC14 vapor 3 hr a day for as long as 6 to 8 weeks. Triglycerides of the liver increased markedly in 50 and 100 ppm groups and very slightly in 10 ppm, showing the striking correlation between the level of CC14 and the amount of triglycerides accumulated. However, in the range of CC14 level adopted, the effect of the repetition of the inhalations was limited and there was no progressive or cumulative change in the amount of hepatic triglycerides. The level of CC14 in adipose tissue also correlated well with the concentration of the vapor, but its accumulation after repeated exposures was not remarkable. Notwith- standing the presence of marked fatty metamorphosis of the liver, serum transaminases remained in the normal range.
A series of 44 workers occupationally exposed to lead and 79 habitants naturally exposed to lead was investigated in order to define more clearly the clinical and biochemical criteria of lead exposure after grouping them into five according to the degree of lead exposure and also to the clinical evidence. The parameters used were hemoglobin (Hb), blood lead (Pb-B), urinary lead (Pb- U), urinary coproporphyrin (Copro), urinary δ-aminolevulinic acid (ALA), and ALA- dehydrase (ALA-D) activity in peripheral red blood cells (RBC) estimations. A statistically significant difference was found between mean values respectively for Pb-B and ALA-D of all five groups and also for Pb-U, ALA, Copro and Hb of three occupationally exposed groups. Furthermore, Pb-B correlated negatively with ALA-D in all five groups, and positively with Pb-U and ALA in three occupational groups. Negative correlations were also observed between ALA-D and each of Pb-U and ALA in three occupational groups. As for naturally exposed groups, a significant difference was found between the urban habitants and the rural habitants in regard to the values for Pb-B and ALA- D and, moreover, a close negative correlation was observed between Pb-B and ALA- D at these "normal" levels of Pb-B. Increased ALA excretions were observed when ALA-D activity was decreased to approximately 40% of normal levels. As for choice of a parameter, Pb-B and ALA were concluded to be of value for assessment of a heavy exposure and also for the clinical assessment, ALA-D for a minimum to slight exposure, and all the parameters including Hb and Copro for the comparison of the different lead exposure as a group. Pb-B above 65 μg/100 g and ALA above 17 mg/1 were almost always associated with symptoms and signs of lead poisoning and were therefore considered to be the upper limits of safe ranges. These levels corresponded to ALA-D activity of 0.250 μmole PBG/1 hr/1 ml RBC.