Effects of mental workload on work ability in primary and secondary school teachers / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To investigate the change pattern of primary and secondary school teachers' work ability with the changes in their mental workload.</p><p><b>METHODS</b>A total of 901 primary and secondary school teachers were selected by random cluster sampling, and then their mental workload and work ability were assessed by National Aeronautics and Space Administration-Task Load Index (NASA-TLX) and Work Ability Index (WAI) questionnaires, whose reliability and validity had been tested. The effects of their mental workload on the work ability were analyzed.</p><p><b>RESULTS</b>Primary and secondary school teachers' work ability reached the highest level at a certain level of mental workload (55.73< mental workload ≤ 64.10). When their mental workload was lower than the level, their work ability had a positive correlation with the mental workload. Their work ability increased or maintained stable with the increasing mental workload. Moreover, the percentage of teachers with good work ability increased, while that of teachers with moderate work ability decreased. But when their mental workload was higher than the level, their work ability had a negative correlation with the mental workload. Their work ability significantly decreased with the increasing mental workload (P < 0.01). Furthermore, the percentage of teachers with good work ability decreased, while that of teachers with moderate work ability increased (P < 0.001).</p><p><b>CONCLUSION</b>Too high or low mental workload will result in the decline of primary and secondary school teachers' work ability. Moderate mental workload (55.73∼64.10) will benefit the maintaining and stabilization of their work ability.</p>

Effects of lead exposure in drinking water on hydrogen peroxide, hydroxyl free radicals and lipid peroxidation levels in brain tissues of rats / 天津医药

Objective To explore the effects of lead acetate on free radicals and lipid peroxidation in the cerebral cor?tex, cerebellum, and hippocampus in rat brains. Methods SD rats (n=48), who were just weaned, were randomly divided in?to 4 groups base on their weight. Then the rats were fed with lead acetate in drinking water at the final concentrations of 0 mg/L (deionized water), 200 mg/L, 400 mg/L, 800 mg/L respectively. Blood lead level as well as the hydroxyl free radical inhibiting activity, the levels of hydrogen peroxide (H2O2) and malondialdehyde (MDA) in cerebral cortex, cerebellum, and hippocam?pus were measured 60 days after lead contamination in water. Results Upon lead exposure, blood lead levels increased sig?nificantly as compared with the control. The hydroxyl free radical inhibiting activity in cerebral cortex, cerebellum, and hip?pocampus decreased significantly in a dose dependent manner of lead(P < 0.05). And they all correlated negatively with blood lead level (r=-0.505,-0.414,-0.448, P<0.05). By contrast, blood lead level was positively correlated with H2O2 and MDA in these brain tissues (r=0.301, 0.411, 0.378, and 0.404, 0.324, 0.510,P < 0.05). Conclusion Lead exposure can lead to lipid peroxidation of rat brain tissues through inducing free radicals.