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81.
Human immunodeficiency virus (HIV) diagnostics are urgently needed in resource-scarce settings. Monitoring of HIV-infected patients requires accurate counting of CD4+ T lymphocytes. However, the current methods for enumeration of CD4+ T lymphocytes are of high cost, technically complex and time-consuming. In this paper, we developed a simple, rapid and inexpensive one-step immunomagnetic method for separating and counting CD4+ T lymphocytes on microfluidic devices with enlarged reaction chambers. CD4+ T lymphocytes were successfully separated and captured from the cell suspension obtained from mouse thymus. CD4 counts were determined under an optical microscope in a rapid and simple format. In order to acquire the maximum efficiency of cell capture, relative parameters were investigated, including section area of the reaction chamber and injection flow rate of the cell suspension. The enlarged reaction chamber with two symmetrical cone-shaped ends was helpful for cell capture, and the maximum capability of captured CD4+ T lymphocytes was about 700 cells μL−1. Our investigations avoided the complex sample pre-treatment, and the entire analysis time was significantly reduced to 15 min. This CD4 counting microdevice had the potential to reduce the cost for HIV diagnosis in resource-limited settings. 相似文献
82.
Biodegradable microspheres were fabricated by poly(?-caprolactone) (PCL) homopolymer and poly(?-caprolactone-b-ethylene oxide) (PCL-b-PEO) amphiphilic block copolymer. The regulation of microsphere surface morphology was successfully achieved by controlled enzymatic degradation. The morphological changes induced by biodegradation and their influences on the growth of MG-63 human osteosarcoma cells were studied. Results based on the evaluation of cytotoxicity and the morphological observation of MG-63 cells cultivated on microspheres showed better growth of cells on the surface of degraded microspheres than on the surface of those undegraded microspheres no matter they were fabricated by homopolymers or copolymers. The influences of morphological changes of microsphere surface before and after biodegradation on MG-63 cell growth were discussed. The results of this work indicated that the biodegradation-induced morphological changes of microspheres could be well controlled and were favorable for MG-63 cell attachment and proliferation. 相似文献
83.
利用溶液共混法以及溶剂挥发法制备了羟基磷灰石(Nano-HA)/聚乳酸(PLA)微粒,再粘结微粒加工成三维多孔Nano-HA/PLA微粒复合生物支架。借助相差显微镜、扫描电子显微镜和MTT法检测了鼠骨髓基质细胞(BMSCs)在该支架材料上的生长情况,通过细胞形态学观察和细胞增殖情况评价了该复合生物支架材料的生物相容性。结果表明,SEM观察到支架材料上培养细胞4d后,细胞主要附着、铺展在支架的低洼处或孔洞处表面,并向孔洞深部沿壁生长;在支架材料上培养细胞8d后,细胞多为梭形形态,并有许多生长角,直接贴附于支架的微粒表面,开始连片生长,有明显的增值,各组没有变形、坏死现象。支架材料上培养细胞2,3,4,5,6和8d的MTT检测表明,各实验组RGR均达到100%以上,细胞毒性为0级;细胞在支架材料上的生长曲线显示,实验组细胞活力比对照组高26%。因此,该Nano-HA/PLA微粒复合生物支架没有细胞毒性,并对细胞有良好的粘附和增殖能力,为较具潜力的骨修复材料。 相似文献
84.
Sicen Wang Meng Sun Yanmin Zhang Hui DuLangchong He 《Journal of chromatography. A》2010,1217(32):5246-5252
The intracellular kinase domains of epidermal growth factor receptor (EGFR) in some tumor cells such as human epidermal squamous cells (A431 cells) are an important target for drug discovery. We have developed a new A431/cell membrane chromatography (A431/CMC)-online–high performance liquid chromatography/mass spectrometry (HPLC/MS) method for screening EGFR antagonists from medicinal herbs such as traditional Chinese medicines (TCMs). In this study, A431 cells with high EGFR expression levels were used to prepare cell membrane stationary phase (CMSP) in an A431/CMC model. The retention fractions eluted from the CMSP column were enriched onto an ODS pre-column and then switched into an HPLC/MS system by combining a 10 port columns switching valve. The screening results found that oxymatrine and matrine from Radix sophorae flavescentis (RSF) were the targeted components which could act on EGFR in similar manner of gefitinib as a control drug. There was a good relationship of their inhibiting effects on EGFR secretion and A431 cell growth in vitro. This new A431/CMC-online-HPLC/MS method can be applied for screening EGFR antagonists from TCMs such as RSF. It will be a useful method for drug discovery with natural medicinal herbs as a leading compound resource. 相似文献
85.
86.
We report a method for the measurement of nematic liquid crystal (NLC) cell parameters i.e., switching voltage, birefringence, retardation, dielectric anisotropy, average tilt angle and change in refractive index with applied DC voltage to LC material. The proposed method is based on optical interferometry and Fourier transform fringe analysis technique, in which we obtain 2-dimensional (2D) phase map of the interferograms as a function of applied voltage. Mach-Zehnder interferometer (MZI) was used for the study of cell parameters and interferograms were recorded at different applied DC voltages to NLC cell using CCD camera. From the phase map, 2D-refractive index distribution of the LC cell with applied voltage was reconstructed. Analytical equations are derived based on optical interferometry and then solved to obtain cell parameters. The present method is fast and can give 2D-cell parameters from only two quick interferograms. 相似文献
87.
Recently V. Krushkal and D. Renardy generalized the Tutte polynomial from graphs to cell complexes. We show that evaluating this polynomial at the origin gives the number of cellular spanning trees in the sense of A. Duval, C. Klivans, and J. Martin. Moreover, after a slight modification, the Tutte–Krushkal–Renardy polynomial evaluated at the origin gives a weighted count of cellular spanning trees, and therefore its free term can be calculated by the cellular matrix-tree theorem of Duval et al. In the case of cell decompositions of a sphere, this modified polynomial satisfies the same duality identity as the original polynomial. We find that evaluating the Tutte–Krushkal–Renardy along a certain line gives the Bott polynomial. Finally we prove skein relations for the Tutte–Krushkal–Renardy polynomial. 相似文献
88.
89.
Two new 8,4′-oxynorneolignans were produced by elicitation of Echinacea purpurea cell suspension cultures with yeast elicitor. Their structures with an unusual (hydroxy)acetyl group were elucidated by spectroscopic methods including gas chromatography (GC) and electrospray ionization (ESI) mass spectrometry. 相似文献
90.