ABSTRACT
Objective@#To investigate the peak time and peak area of elements in cadmium telluride quantum dots (CdTe QDs) using size exclusion chromatography-high-performance liquid chromatography-inductively coupled plasma mass spectrometry, as well as the biological stability of CdTe QDs in vivo and in vitro.@*Methods@#Transmission electron microscope and ultraviolet fluorescence were used for characterization and synthesis of water-soluble CdTe QDs, and CdTe QDs were added to double-distilled water, mobile phase, or bovine serum medium to observe the change in stability after different periods of time. CdTe QDs were injected into the vein of mice, and the changes in the morphology of CdTe QDs in serum and the liver were measured at 1, 24, and 72 hours after exposure. Size exclusion chromatography-high-performance liquid chromatography was used for the elution of the compounds in the solution based on their volume, and then inductively coupled plasma mass spectrometry was performed for the eluent. The flow time of 114Cd and 130Te and molar ratio were used for qualitative analysis of CdTe QDs, and the peak area was used to judge whether CdTe QDs were degraded.@*Results@#CdTe QDs were diluted to a concentration of 0.5 mmol/L with double-distilled water and then placed in a dark place at room temperature; CdTe QDs were completely degraded after 60 minutes. CdTe QDs were diluted to a concentration of 0.005 mmol/L with a mobile phase, and the peak of CdTe QDs was not detected. After CdTe QDs were placed in a dark place at room temperature for 48 hours at a concentration of 0.005 mmol/L in bovine serum mediumin vitro, the peak area of 114Cd was 6179841-7346084, and the peak area of 130Te was 1077913-1191066. CdTe QDs had the highest peak area at 1 hour after exposure, and the peak areas of 114Cd and 130Te were 18183894 and 25187987, respectively. CdTe QDs were quickly degraded in the liver; at 1 hour after exposure, the degradation products of CdTe QDs containing Cd were observed in liver tissue homogenate, and CdTe QDs were largely degradedat 24 hours.@*Conclusion@#This method can be used to investigate the biological stability of CdTe QDs. CdTe QDs are degraded in the liver and produce Cd2+, which may cause toxic reaction.
ABSTRACT
Objective To analyze the effect of stroke duration on the cognitive function in the elderly population in Beijing.Methods Based on the Research Project of Beijing Chronic Disease Combined with Common Elderly Syndrome Community Management Practices,a cross-sectional study was used.From July 2013 to December 2014,the old population in 4 districts and a county (Xicheng District,Fangshan District,Tongzhou District and Yanqing County) in Beijing were sampled with the multi-stage,randomized and stratified sampling.A total of 3 024 subjects were enrolled in the study.The data were obtained from the questionnaires and clinical examinations.Mini-Mental State Examination (MMSE) was used as the evaluation index of cognitive function.The subjects were divided into either a normal cognitive function group (MMSE>26,n=1 878) or a cognitive impairment group (MMSE≤26,n=1 146) according to the MMSE scores.A multiple logistic regression model was used to analyze the effects of hemorrhagic stroke,ischemic stroke,and asymptomatic stroke,as well as disease duration on cognitive function.Results After adjusting for the confounding factors,such as sex,age,educational level,marriage,smoking,and alcohol consumption,the risks of occurring cognitive impairment in patients with hemorrhagic stroke in stroke duration for 1-3,4-10 and >10 years were OR 3.019 (95％CI 0.974-9.361,P=0.056),8.652 (95％CI 2.924-25.601,P10 years were 1.000 (95％CI 0.636-1.571,P=1.000),1.874 (95％CI 1.231-2.853,P=0.003),2.439 (95％CI 1.386-4.291,P=0.002) times of those without occurring stroke population.Stroke duration for 4-10 years in patients with hemorrhagic stroke and stroke duration for 4-10 and >10 years in patients with ischemic stroke were all the risk factors for occurring cognitive dysfunction.Conclusion For patients with stroke,stroke duration or long-term effects has a certain impact on cognitive function.