Decades of investigation on DNA methylation have led to deeper insights into its metabolic mechanisms and biological functions.This understanding was fueled by the recent development of genome editing tools and our im...Decades of investigation on DNA methylation have led to deeper insights into its metabolic mechanisms and biological functions.This understanding was fueled by the recent development of genome editing tools and our improved capacity for analyzing the global DNA methylome in mammalian cells.This review focuses on the maintenance of DNA methylation patterns during mitotic cell division.We discuss the latest discoveries of the mechanisms for the inheritance of DNA methylation as a stable epigenetic memory.We also highlight recent evidence showing the rapid turnover of DNA methylation as a dynamic gene regulatory mechanism.A body of work has shown that altered DNA methylomes are common features in aging and disease.We discuss the potential links between methylation maintenance mechanisms and diseaseassociated methylation changes.展开更多
The concept and structure of serial-connection multi-chamber (SCMC) micropumps with cantilever valves is introduced. The SCMC micropump, which can be manufactured using conventional production techniques and materials...The concept and structure of serial-connection multi-chamber (SCMC) micropumps with cantilever valves is introduced. The SCMC micropump, which can be manufactured using conventional production techniques and materials, has a multi-layer circular planar structure. The border-upon piezoelectric actuators of a SCMC micropump work in anti-phase, as a result the pumping performance is similar to that of several single-chamber pumps running in series. The theoretical analysis shows that the pumping performance of a SCMC micropump depends not only on the characteristic and geometrical parameters of the piezoelectric actuators, but also on the number of pump chambers. Both flowrate and pressure of a SCMC pump can be enhanced to a certain extent. Four piezoelectric micropumps with different chambers were fabricated and tested. The testing results show that the enhancing extents of the flowrate and pressure of a SCMC piezoelectric micropump are different. The maximum flowrate and pressure of the four-chamber pump achieved are 2.5 times and 3.6 times those of the single-chamber pump achieved.展开更多
Background Researchers have recently demonstrated that thrombospondin-1 （TSP-1） has an important function in regulating neovascularization. Whether it inhibits or accelerates neovascularization, however, is still co...Background Researchers have recently demonstrated that thrombospondin-1 （TSP-1） has an important function in regulating neovascularization. Whether it inhibits or accelerates neovascularization, however, is still controversial. We found few reports about the correlation between TSP-1 and vascularization in mucoepidermoid carcinoma. In this research, the distribution and expression of TSP-1 in mucoepidermoid carcinoma were investigated. We also analyzed （1） the correlation between the expression of TSP-1 and microvessel density （MVD）, as an indicator of neovascularization activity, and （2） the effect of TSP-1 on neovascularization and tumor growth in the subcutaneous xenotransplanted model of mucoepidermoid carcinoma. Method （1） The sites and intensity of expression of TSP-1 and the MVD were analyzed in 45 cases of mucoepidermoid carcinoma after surgery by the method of streptavidin-peroxidase （SP） immunohistochemistry; and （2） recombinant human thrombospondin-1 （rhTSP-1） was injected twice a week for five consecutive weeks around the tumor in the subcutaneous xenotransplanted tumor model of mucoepidermoid carcinoma in nude mice. Each week, the tumor size was measured, in order to draw the growth curve of the xenotransplanted tumor model of mucoepidermoid carcinoma, and MVD was measured. Results （1） The positive expression of TSP-1 protein was 57.78% （26/45）. Most positive staining for TSP-1 was found in the cytoplasm of the cancer cells, while some staining occurred in the extracellular matrix. The mean MVD in 45 cases of m ucoepidermoid carcinoma was 58.17±19.77 per 100 visual fields. Tumors with a high expression of TSP-1 showed a low MVD value, and the TSP-1 immunocompetence and microvessel density showed a significant negative correlation （rs=-0.947, P 〈0.001）. （2） The xenotransplanted tumors with the injection doses of 1.25, 0.75 and 0.25 ug/ml respectively were 36.97%, 53.36% and 73.61% of the size of the control group （（451±92）, （651±113）, （898±86） and （1220±157） mm^3 respectively, F=-53.167, P 〈0.001）, and their weights were respectively 35.14%, 51.35% and 70.27% of the control group （（1.3±0.5）, （1.9±0.5）, （2.6±0.3）, and （3.7±0.7） g respectively, F=-62.669, P 〈0.001）. Their MVDs were 25.00%, 45.93%, and 72.20% respectively of the control group and concentration dependent （15.43±3.45, 28.35±4.24, 44.57±3.35 and 61.73±5.43 per 100 visual fields respectively, F=54.582, P 〈0.001）. Conclusions The TSP-1 has a higher expression in mucoepidermoid carcinoma and the expression has a significant negative correlation with neovascularization. The TSP-1 inhibits neovascularization and tumor growth, and it might be a new biological therapy for treatment of patients with mucoepidermoid carcinoma.展开更多
基金supported by the Chinese Ministry of Science and Technology (2019YFA0801401 to B.Z.)the Chinese Academy of Sciences (XDB39000000 and QYZDY-SSW-SMC031 to B.Z.+1 种基金2019 Special Research Assistant Funding to Y.L.)the National Natural Science Foundation of China (32000559 to Y.L.)。
文摘Decades of investigation on DNA methylation have led to deeper insights into its metabolic mechanisms and biological functions.This understanding was fueled by the recent development of genome editing tools and our improved capacity for analyzing the global DNA methylome in mammalian cells.This review focuses on the maintenance of DNA methylation patterns during mitotic cell division.We discuss the latest discoveries of the mechanisms for the inheritance of DNA methylation as a stable epigenetic memory.We also highlight recent evidence showing the rapid turnover of DNA methylation as a dynamic gene regulatory mechanism.A body of work has shown that altered DNA methylomes are common features in aging and disease.We discuss the potential links between methylation maintenance mechanisms and diseaseassociated methylation changes.
文摘The concept and structure of serial-connection multi-chamber (SCMC) micropumps with cantilever valves is introduced. The SCMC micropump, which can be manufactured using conventional production techniques and materials, has a multi-layer circular planar structure. The border-upon piezoelectric actuators of a SCMC micropump work in anti-phase, as a result the pumping performance is similar to that of several single-chamber pumps running in series. The theoretical analysis shows that the pumping performance of a SCMC micropump depends not only on the characteristic and geometrical parameters of the piezoelectric actuators, but also on the number of pump chambers. Both flowrate and pressure of a SCMC pump can be enhanced to a certain extent. Four piezoelectric micropumps with different chambers were fabricated and tested. The testing results show that the enhancing extents of the flowrate and pressure of a SCMC piezoelectric micropump are different. The maximum flowrate and pressure of the four-chamber pump achieved are 2.5 times and 3.6 times those of the single-chamber pump achieved.
基金This study was supported by the NatiOnal Natural Science Foundation of China （No. 0040305401042）.Acknowledgements： We would like to thank Steven Pan and Mary Meyer for the assistance in polishing the paper. Their innovative suggestions and advice contributed significantly to the final version of the paper.
文摘Background Researchers have recently demonstrated that thrombospondin-1 （TSP-1） has an important function in regulating neovascularization. Whether it inhibits or accelerates neovascularization, however, is still controversial. We found few reports about the correlation between TSP-1 and vascularization in mucoepidermoid carcinoma. In this research, the distribution and expression of TSP-1 in mucoepidermoid carcinoma were investigated. We also analyzed （1） the correlation between the expression of TSP-1 and microvessel density （MVD）, as an indicator of neovascularization activity, and （2） the effect of TSP-1 on neovascularization and tumor growth in the subcutaneous xenotransplanted model of mucoepidermoid carcinoma. Method （1） The sites and intensity of expression of TSP-1 and the MVD were analyzed in 45 cases of mucoepidermoid carcinoma after surgery by the method of streptavidin-peroxidase （SP） immunohistochemistry; and （2） recombinant human thrombospondin-1 （rhTSP-1） was injected twice a week for five consecutive weeks around the tumor in the subcutaneous xenotransplanted tumor model of mucoepidermoid carcinoma in nude mice. Each week, the tumor size was measured, in order to draw the growth curve of the xenotransplanted tumor model of mucoepidermoid carcinoma, and MVD was measured. Results （1） The positive expression of TSP-1 protein was 57.78% （26/45）. Most positive staining for TSP-1 was found in the cytoplasm of the cancer cells, while some staining occurred in the extracellular matrix. The mean MVD in 45 cases of m ucoepidermoid carcinoma was 58.17±19.77 per 100 visual fields. Tumors with a high expression of TSP-1 showed a low MVD value, and the TSP-1 immunocompetence and microvessel density showed a significant negative correlation （rs=-0.947, P 〈0.001）. （2） The xenotransplanted tumors with the injection doses of 1.25, 0.75 and 0.25 ug/ml respectively were 36.97%, 53.36% and 73.61% of the size of the control group （（451±92）, （651±113）, （898±86） and （1220±157） mm^3 respectively, F=-53.167, P 〈0.001）, and their weights were respectively 35.14%, 51.35% and 70.27% of the control group （（1.3±0.5）, （1.9±0.5）, （2.6±0.3）, and （3.7±0.7） g respectively, F=-62.669, P 〈0.001）. Their MVDs were 25.00%, 45.93%, and 72.20% respectively of the control group and concentration dependent （15.43±3.45, 28.35±4.24, 44.57±3.35 and 61.73±5.43 per 100 visual fields respectively, F=54.582, P 〈0.001）. Conclusions The TSP-1 has a higher expression in mucoepidermoid carcinoma and the expression has a significant negative correlation with neovascularization. The TSP-1 inhibits neovascularization and tumor growth, and it might be a new biological therapy for treatment of patients with mucoepidermoid carcinoma.
