Based on introducing digital certificate related concepts, the paper compares the similarities and differences of digital sig-nature soft and hard certificates from the aspects of implementation process, implementation condition, convenience, security, law validi-ty, maintainability, etc.Combining with the actual status of information system, it analyzes the selection of digital signature.

Objective]To explore the metastasis regulatory of lymph node of papillary thyroid cancer and to analyze the influence factors.[Methods]Clinical data of 375 papillary thyroid cancer patients at our hospital between Jun 2011 and Sep 2015 were retrospectively reviewed and summarized the metastasis regulatory of lymph nodes and the tumor characteristics.[Results]All selected patients were diagnosed papillary thyroid cancer. The Total metastasis rate of cervical lymph node was 67.47%,the metastasis rate of region Ⅵ lymph nodes was 64.27%;the metastasis rate of region Ⅱ~Ⅴ lymph nodes was 36.53%. The metastasis rate of lymph nodes of the patients with tumor diameter over 1 cm,breaking through thyroid membrane and invading the cervical muscle were significantly increased(P < 0.05).[Conclusion]The central group lymph nodes were the most metastasis region of papillary thyroid cancer and should routinely be dissected by the first time of surgery. When the tumor diameter greater than 1 cm or cancer breakthrough thyroid membrane and/or invading the cervical muscles ,the ipsilateral lateral neck lymph nodes should be dissected at the same time.

Objective To investigate the role of SIAH2 protein in the occurrence and development of hepatocellular carcinoma (HCC). Methods Human HCC Bel-7404 cells in logarithmic growth phase were inoculated. Empty carrier small interference ribonucleic acid (siRNA) and SIAH2 siRNA were transfected in human HCC Bel-7404 cells. Then the cells were divided into 2 groups:control-siRNA group and SIAH2-siRNA group. Theβ-actin was taken as control, and the expression of SIAH2 protein in human HCC Bel-7404 cells of 2 groups was detected by Western Blot. The proliferation of cells in 2 groups was detected by methyl thiazolyl tetrazolium (MTT) assay. Cell migration in 2 groups was observed by cell scratch test. Cell invasion in 2 groups was observed by Transwell assay. The data in 2 groups were compared using t test. Results The average relative expression of SIAN2 in control-siRNA and SIAH2-siRNA group were 0.71±0.02, 0.33±0.01 respectively. The expression of SIAN2 in SIAH2-siRNA group decreased obviously compared with that in control-siRNA group (t=-4.629, P<0.05). The proliferation rate in SIAH2-siRNA group also decreased obviously. The cell migration rate in SIAH2-siRNA group[(14.3±0.4)%] was significantly lower than that in control-siRNA group [(45.3±0.4)%]( t=-3.689, P<0.05). The membrane permeating cell count in SIAH2-siRNA group (122±7) was signiifcantly less than that in control-siRNA group (563±10) (t=-3.428, P<0.05). Conclusion SIAH2 protein can promote the proliferation, migration and invasion of HCC cells and thus accelerate the occurrence and development of HCC.