ABSTRACT
Objective To investigate tumor cell killing effect of superparamagnetic Fe3O4 nanoparticles with cubic phase through magneto-mechanical force under a low-frequency vibrating magnetic field ( VMF). Methods A kind of strong magnetic and irregular-shaped Fe3O4 nanoparticles with cubic phase was synthesized by coprecipitation method. The Fe3O4 nanoparticles were exposed to a self-developed VMF and cell killing efficiency of the Fe3O4-mediated magneto-mechanical force was investigated. Results VMF alone had no effects on cell viability. After Fe3O4 nanoparticles were added, the cell viability significantly decreased with prolonging the VMF treatment time and increasing the Fe3O4 nanoparticle concentration. Lactate dehydrogenase released by damaged cells also increased with prolonging the VMF exposure time. Conclusions The irregular-shaped Fe3O4 nanoparticles can transfer magneto-mechanical force to tumor cells under VMF, cause structural damage of cells and result in cell death. The VMF generator developed in this study has simple structure and it is safe for use and convenient for operation. The developed magnetic nanoparticles and the corresponding cancer cell killing technique have the potential for clinical transformation.
ABSTRACT
Objective@#To analyze the detection rate of sleep problems such as sleep delay and deficiency in preschool children in the middle and lower reaches of the Yangtze River in China,and to provide the reference for the standard of sleeping mode among preschool students.@*Methods@#From October to November 2017, a questionnaire survey was conducted among 27 200 preschool children in 11 cities in Hubei, Anhui and Jiangsu provinces in the middle and lower reaches of the Yangtze River in China. Epidemiology of sleep delays, deficiencies and sleep patterns in preschool children was described.@*Results@#The detection rate of sleep problems in preschool children in the middle and lower reaches of the Yangtze River was 15.3%. Taking the length of sleep and bedtime as the main analysis points, it was found that the average sleeping time point of each age group was 21:31, and the detection rate of bedtime delay was 86.5%. The average length of sleep was (10.60±1.12) hours. The detection rate of sleep deprivation in preschool children was 15.7%. Sleep delay was positively correlated with girls, age increase and parents’ higher educational level (P<0.05), and negatively correlated with living in the city, non-only child and bedroom without TV (P<0.01) .The detection rate of sleep deprivation was positively correlated with children of high age group (4yearold group：OR=1.32，95%CI=1.19-1.46；5-year-old group：OR=2.10，95%CI=1.91-2.32；6-year-old group：OR=2.47，95%CI=2.20-2.77)(P<0.01), and negatively correlated with no TV in bedroom (OR=0.91，95%CI=0.84-0.98) and no light in sleep (OR=0.87，95%CI=0.78-0.97)(P<0.05).@*Conclusion@#Preschool children sleep delay and sleep deprivation and other sleep problems are more prominent, affected by family environment and other factors.