Endocan-expressing microvessel density as a prognostic factor for survival in human gastric cancer

AIM: To investigate the expression of endocan in tumour vessels and the relationships between endocan and the expression of vascular endothelial growth factor(VEGF) and prognosis in gastric cancer.METHODS: This study included 142 patients with confirmed gastric cancer in a single cancer centre between 2008 and 2009. Clinicopathologic features were determined, and an immunohistochemical analysis of endocan-expressing microvessel density(MVD)(endocan-MVD), VEGF and vascular endothelial growth factor receptor 2(VEGFR2) was performed. Potential relationships between endocan-MVD and clinicopathological variables were assessed using a Student's t-test or an analysis of variance test. Spearman's rank correlation was applied to evaluate the relationship between endocan-MVD and the expression of VEGF/VEGFR2. long-term survival of these patients was analysed using univariate and multivariate analyses.RESULTS: Positive staining of endocan was observed in most of the gastric cancer tissues(108/142) and in fewer of the normal gastric tissues. Endocan-MVD was not associated with gender or histological type(P > 0.05), while endocan-MVD was associated with tumour size,Borrmann type, tumour differentiation, tumour invasion, lymph node metastasis and TNM stage(P < 0.05). According to the Spearman's rank correlation analysis, endocan-MVD had a positive correlation with VEGF(r = 0.167, P = 0.047) and VEGFR2(r = 0.410, P = 0.000). The univariate analysis with a log-rank test indicated that the patients with a high level of endocan-MVD had a significantly poorer overall survival rate than those with a low level of endocan-MVD(17.9% vs 64.0%, P = 0.000). The multivariate analysis showed that a high level of endocan-MVD was a valuable prognostic factor.CONCLUSION: Endocan-MVD significantly correlates with the expression of VEGF and VEGFR2 and is a valuable prognostic factor for survival in human gastric cancer.

Two-frequency amplification in a semiconductor tapered amplifier for cold atom experiments

Simultaneous two-frequency amplification is highly desirable in cold atom experiments. The nonlinear response would appear in the two-frequency amplification with a semiconductor tapered amplifier（TA） and has a direct influence on the experimental result. We investigated in detail the effects of frequency difference, total power, and power ratio of two seeding lasers on the output components based on a simplified theoretical model. The simulation results showed that the multiple sideband generation in the amplifier due to self-phase and amplitude modulation could be suppressed and the TA tended to linearly amplify the power ratio between two-frequency components, when the two seeding lasers had a large frequency difference. This was verified experimentally in the output power ratio measurement via a calibrated Fabry-Perot interferometer method with a good linearity and an uncertainty of 1%. We also discussed the consequences of power ratio responses in the amplification in light of cold atom experiments, especially in the ac Stark shift related phase error of Raman-type atom interferometers（AIs）. It was shown that the fluctuation of intensity ratio of Raman beams may induce significant systematic errors for an AI gyroscope.