Sadafumi Takise

Combined effects of lead and edta on Na+,K+‐ATPase activity of erythrocyte membranes

Erythrocyte Na+,K+-ATPase activity increased significantly in lead workers of a lead refining factory when measured with EDTA and compared to the controls without EDTA. The enzyme activity measured with EDTA increased in the following order: controls less than office workers in a lead refining factory less than lead workers. A positive correlation existed between blood lead and enzyme activity with EDTA (r = 0.380, p less than 0.10), and the activity without EDTA (r = 0.398, p less than 0.05). A negative correlation was found between sodium in erythrocytes and enzyme activity with EDTA (r = -0.437, p less than 0.05), and the activity without EDTA (r = -0.416). But no relationship was observed between enzyme activities and potassium in erythrocytes. A positive correlation between enzyme activity with EDTA and that without EDTA was observed (r = 0.452, p less than 0.05). With addition of lead to fragments of erythrocyte membranes, a significant decrease occurred in the activity of the enzyme without EDTA, whereas no change was observed with EDTA. No significant change occurred in the enzyme activity with and without EDTA upon addition of lead to blood. The maximum level of lead in membrane fragments (lead combined with membranes) of workers exposed to lead was 0.60 microgram/mg protein, and that in the experiment of addition to blood was 7.0 micrograms/mg protein.

Pupillary changes due to work using visual display terminals

SummaryIn order to measure the degree of ocular fatigue and general fatigue among the workers using visual display terminal (VDT), pupillary dynamics were measured with open-loop light stimulation for 26 subjects of a mean age of 25.9 years. VDT loads were TV games for 30 min under indirect light of 100 lux. The eight parameters of pupillary light reflex with open-loop pupillometer were examined before and after VDT loads. On the right eyes, two parameters and one value increased 9.2% (Students t-test: P<0.005, max.), 25.7% (Students t-test: P< 0.005, Min.) and 14.8% (Students t-test: P< 0.005, min/max) just after the load and then gradually decreased and returned to the pre-load level after a 10 to 15-min rest period. Two parameters increased 11.7% (Students t-test: P<0.05, Min.) and 12.9% (Students t-test: P< 0.05, VD), one parameter decreased −9.0% (Students t-test: P<0.05, 0.63D) and three parameters were constant (Students t-test: L, A and VC) just after the load. On the left eyes, the same tendencies were observed. But there were no significant differences (Students Mest) between the right and left eyes. The change pattern of the eight parameters were small in degree and similar to the changes when the sympathetic nervous system was activated.