Problems in the Extraction of Polycyclic Aromatic Hydrocarbons from Diesel Particulate Matter

In this work, a comparison between Soxhlet, ultrasonic, and microwave-assisted extraction (MAE) (using hexane:acetone 1:1) of polycyclic aromatic hydrocarbons (PAHs) from SRM 1650 diesel particulate matter was made. As good recoveries were not obtained for the higher molecular weight compounds, MAE with toluene and dichloromethane was also tested. Achieved recoveries were compared with the results obtained in the same assays made with SRM 1648 urban particulate matter and real atmospheric particulate samples. In order to explain the difficulty of the extraction of PAHs from SRM 1650 in comparison to SRM 1648 and real atmospheric particulate samples, elemental analysis, X-ray diffraction, and particle analysis using scanning electron microscopy coupled to an automatic computer imaging system were also made. It is important to notice that SRM 1650 shows a high percentage of carbon and differences in the morphology of the particles between SRM 1650 and SRM 1648 were observed.     

氨氯地平对人乳腺癌细胞MCF-7细胞周期和周期蛋白表达的影响及其调控机制

目的探讨氨氯地平对人乳腺癌细胞MCF-7细胞周期及周期蛋白表达的影响及其调控机制。方法以不同浓度的氨氯地平处理对数生长期的MCF-7细胞,MTT法检测细胞增殖水平;流式细胞仪分析细胞周期;免疫细胞化学法检测细胞周期蛋白cyclinD1、p21和p53的表达。结果氨氯地平呈剂量和时间依赖性抑制MCF-7细胞增殖,IC50为14.439μmol/L;经7.220μmol/L(0.5IC5)0、14.439μmol/L(1IC5)0和28.880μmol/L(2IC50)氨氯地平处理48h,G0/G1期细胞比例较对照组明显增高;经7.220μmol/L氨氯地平处理48h,MCF-7细胞中cyclinD1蛋白表达降低,p21和p53蛋白表达升高。结论氨氯地平对MCF-7细胞的增殖具有抑制作用,此作用与使细胞阻滞于G1期有关,其机制与调控细胞周期相关蛋白cyclinD1、p21和p53的表达有关。     

Kozak序列对TIMP1基因在人乳腺癌细胞MCF-7中表达的影响

目的探讨Kozak序列对基质金属蛋白酶抑制剂1(TIMP1)基因在人乳腺癌细胞MCF-7中表达的影响。方法构建pcDNA3.1-TIMP1和pcDNA3.1-TIMP1-K(含有Kozak序列)重组真核表达质粒,用FugeneHD转染试剂将重组表达质粒转染MCF-7细胞,采用荧光定量PCR和Western blot检测pcDNA3.1-TIMP1和pcDNA3.1-TIMP1-K在MCF-7细胞中表达的差异。结果重组真核表达质粒经PCR、双酶切及测序鉴定,证明构建正确。质粒pcDNA3.1-TIMP1-K转染细胞比空白对照细胞TIMP1基因mRNA表达量高约0.95倍,蛋白表达量高0.43倍;而质粒pcDNA3.1-TIMP1转染细胞比空白对照细胞mRNA表达量高0.37倍,蛋白表达量高0.25倍。结论质粒pcDNA3.1-TIMP1-K与pcDNA3.1-TIMP1在MCF-7细胞中mRNA和蛋白表达水平均存在差异,Kozak序列提高了TIMP1基因的表达。