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.

Adult↗

PubMedDate not supplied

Study on osmotic fragility of red blood cells in workers exposed to styrene or a mixture of toluene and methyletylketone using a coil planet centrifuge.

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Adult↗

PubMedDate not supplied

Selective caries removal with air abrasion.

The purpose of this study was to evaluate selective caries removal using an air-abrasive technique. Alumina powders, glass beads, crushed glass powders, and crushed powders of polycarbonate resin were applied to intact human enamel, dentin, and artificially demineralized dentin (caries-model dentin). Furthermore, the effect of the particle size of abrasives and air pressures on the abraded depths was examined. When alumina powders and glass beads were used, the abraded depths of enamel, dentin, and caries model increased as the particle size and air pressure increased. Alumina powders and crushed glass powders abraded intact enamel and dentin more than the caries-model dentin, whereas glass beads abraded the caries-model dentin more than the intact enamel and dentin. Only crushed powders of polycarbonate resin abraded the caries-model dentin without reducing intact enamel and dentin. With hard particles, such as alumina powders, glass beads, or crushed glass powders, selective caries removal by the air-abrasive technique appeared to be difficult to achieve, even if the particle size and the air pressure were changed. Crushed powders of polycarbonate resin that reduced only the caries-model dentin are harder than caries-model dentin, but softer than intact enamel and dentin. This study elucidated the possibility of selective carious dentin removal with the air-abrasive technique.

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