Microfluidic chips can be used to realize continuous cryoprotectants (CPA) loading/unloading for oocytes, reducing osmotic damage and chemical toxicity of CPA. In this study, five different Y-shape microfluidic chips were fabricated to realize the continuous CPA loading/unloading. The effects of flow rate, entrance angle, aspect ratio and turning radius of microchannels on the mixing efficiency of microfluidic chips were analyzed quantitatively. The experimental results showed that with the decrease of flow rates, the increase of aspect ratios and the decrease of turning raradius of microchannel, the mixing length decreased and the mixing velocity was promoted, while the entrance angle had little effect on the mixing efficiency. However, the operating conditions and structural parameters of the chips in practical application should be determined based on an overall consideration of CPA loading/unloading time and machining accuracy. These results would provide a reference to the application of microfluidic chip in CPA mixing.
ObjectiveTo quantitate expression of miR21 in rectal cancer of different tumor stages and discuss their significances. MethodThe expression of miR21 was detected and quantitated in the rectal cancer tissues and corresponding adjacent normal tissues of 40 patients with rectal cancer in this hospital from August 2012 to October 2012 by Taq Man microRNA assay. ResultsThe significant overexpression of miR21 was observed in the rectal cancer tissues (4.122±1.973 versus 1.825±0.661, P=0.000)as compared with the corresponding adjacent normal tissues. The expressions of miR21 in the rectal cancer tissues of N1-N2 and Dukes C-D stages were significantly higher than those in the rectal cancer tissues of N0(4.852±2.344 versus 3.391±1.171, P=0.019)and Dukes A-B stage(4.787±2.304 versus 3.386±1.203, P=0.021). From N0 to N2 stage, the expression of miR21 increased progressively in the rectal cancer, and the expression in the rectal cancer tissues of N2 stage was significantly higher than that in the N0 stage(5.556±1.500 versus 3.391±1.171, P=0.010). And receiver operating characteristics curve analysis showed that miR21 could discriminate N 0 stage from N1-N2 stage with a 0.698 area under curve(AUC), 50.0% sensitivity and 90.0% specificity, Dukes C-D stage from A-B stage with a 0.689 AUC, 42.9% sensitivity and 94.7% specificity. ConclusionmiR21 appears to have a potential correlation with N and Dukes stages of rectal cancer, which cautiously and optimistically suggests that it could be a potential novel biomarker for predicting tumor stage preoperatively.