AIM:To investigate the correlation between mitogen-activated protein kinase (MAPK) signal transduction pathway and multidrug resistance (MDR) in MGC803 cells.METHODS:Western blot was used to analyze the expression of ...AIM:To investigate the correlation between mitogen-activated protein kinase (MAPK) signal transduction pathway and multidrug resistance (MDR) in MGC803 cells.METHODS:Western blot was used to analyze the expression of MDR associated gene in transient vincristine (VCR) induced MGC803 cells, which were treated with or without the specific inhibitor of MAPK, PD098059.Morphologic analysis of the cells treated by VCR with or without PD098059 was determined by Wright-Giemsa staining. The cell cycle analysis was performed by using flow cytometric assay and the drug sensitivity of MGC803 cells which were exposed to VCR with or without PD098059 was tested by using MTT assay.RESULTS:Transient exposure to VCR induced P-gp butnot MRP1 or GST-π expression in MGC803 cells and the expression of P-gp was inhibited by PD098059.Apoptotic bodies were found in the cells treated with VCR or VCR+PD098059. FCM results indicated that more MGC803 cells showed apoptotic phenotype when treated by VCR and PD098059 (rate:31.23%) than treated by VCR only (rate:18.42%) (P<0.05).The IC50(284±13.2 μg/L) of MGC803 cells pretreated with VCR was 2.24-fold as that of negative control group (127±17.6μg/L) and 1.48-fold as that of the group treated with PD098059 (191±27.9μg/L).CONCLUSION:This study shows that the expression of P-gp can be induced by transient exposure to VCR and this induction can be prevented by PD098059, which can block the activity of MAPK. MAPK signal transduction pathway may play some roles in modulating MDR1 expression in gastric cancer.展开更多
OBJECTIVE To investigate the effect of a specific inhibitor PD098059 of the extracellular-signal regulated protein kinase (ERK) pathway on the P-glycoprotein (P-gp)-mediated resistance of colon cancer cell lines SW480...OBJECTIVE To investigate the effect of a specific inhibitor PD098059 of the extracellular-signal regulated protein kinase (ERK) pathway on the P-glycoprotein (P-gp)-mediated resistance of colon cancer cell lines SW480/VCR and CoLo205NCR.METHODS SW480NCR and CoLo205NCR cells were generated byexposuring SW480 and CoLo205 cells to vincristine (VCR) (30 ng/ml) for 72h, which resulted in a comparatively higher level of P-gp expression.Western blotting was used to analyze P-gp, MRP, LRP, GST-'rr and TOPOIIexpression after exposuring the SW480 and CoLo205 cells to VCR (30 ng/ml)for 72 hrs. P-gp and pERK1/2 expressions was analyzed in SW480NCR andCoLo205/VCR cells treated with or without the specific inhibitor of MEK,PD098059. The MTT assay was used to determine the susceptibility ofSW480NCR and CoLo205NCR cells to VCR, treated with or withoutPD098059.I^F.SULI"S The results showed that VCR induced a comparatively higher levelof P-gp expression in the cell lines, but not that of MRP, LRP, GST-n- orTOPOII. P-gp expression levels were depressed significantly in SW480/VCR and COLO205/VCR cells by the specific inhibitor of MEK, PD098059.The IC50 (248 +19.6 and 215 +10.7 ng/ml) to VCR of SW480/VCR andCoLo205/VCR cells exhibited a 2.16 and 2.03-fold higher resistancecompared to the negative control group (SW480 and CoLo205 cells)(115+15.6 and 106 +11.9 ng/ml), but a 1.35 and 1.21 -fold higher resistance thanthe group treated with VCR (30 ng/ml)+ PD098059 (184 + 21.8 and 177+19.4 ng/ml).CONCLUSION This study shows that the expression of P-gp can beinduced by exposuring cells to VCR, and that this induction can be reversedby inhibiting the ERK signaling pathway at the point of MEK by its specificinhibitor, PD098059. The ERK signal-transduction pathway may play a rolein modulating mdrl expression in colon cancer.展开更多
The use of valley excitonic states of transition metal dichalcogenides to store and manipulate information is hampered by fast carrier recombination and short valley lifetime.We propose theoretically a scheme to overc...The use of valley excitonic states of transition metal dichalcogenides to store and manipulate information is hampered by fast carrier recombination and short valley lifetime.We propose theoretically a scheme to overcome such an obstacle,by applying a tilted exchange field through the magnetic proximity effect on monolayer MoS_(2).While the in-plane component of the exchange field brightens the dark exciton by spin mixing,the out-of-plane field can effectively gate the emission with an ON/OFF ratio of 2700.Importantly,the brightening is valley selective,leading to nearly 100% valley and spin polarization at room temperature.The resulting strongly gateable dark-exciton emission with long lifetime and near unity valley polarization makes it convenient to manipulate the valley degree of freedom,which may offer new paradigm for information processing and transmission.展开更多
本研究采用水热-冷冻干燥-煅烧的方法成功制备了铜掺杂硫化锡负载氧化石墨烯气凝胶(Cu x SnSO@GO),并采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和紫外-可见光反射分析(UV-vis DRS)对材料进行表征,研究了不同Cu...本研究采用水热-冷冻干燥-煅烧的方法成功制备了铜掺杂硫化锡负载氧化石墨烯气凝胶(Cu x SnSO@GO),并采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和紫外-可见光反射分析(UV-vis DRS)对材料进行表征,研究了不同Cu掺杂量和不同反应时间对光催重整纤维素酶解液产乳酸的影响。结果表明,铜成功的掺入到SnS_(2)结构中,产生表面硫缺陷,改变了SnS_(2)的带隙,提高了SnS_(2)的光催属性。此外,煅烧工艺制备的Cu x SnSO@GO改善了光生电子和空穴的分离效率,显著提高了光催化效率。Cu x SnSO@GO在可见光照射下能够高效的光催重整纤维素酶解液产乳酸,当Cu掺杂量x=0.06反应时间为4 h时,Cu x SnSO@GO具有38.8%的最佳产率。Cu x SnSO@GO形成的表面硫空位、高吸收性、可调节的能带结构以及煅烧后形成的Cu x SnS_(2)-SnO 2异质结都有利于乳酸的选择性转化,这为研究生物质光催化重整的机理提供了一种新的途径。展开更多
Based on the microorganism kinetic model, the formula for computing hydraulic retention time in a membrane bioreactor system (MBR) is derived. With considering HRT as an evaluation index a combinational approach was u...Based on the microorganism kinetic model, the formula for computing hydraulic retention time in a membrane bioreactor system (MBR) is derived. With considering HRT as an evaluation index a combinational approach was used to discuss factors which have an effect on MBR. As a result, the influencing factors were listed in order from strength to weakness as: maximum specific removal rate K , saturation constant K s, maintenance coefficient m , maximum specific growth rate μ m and observed yield coefficient Y obs . Moreover, the formula was simplified, whose parameters were experimentally determined in petrochemical wastewater treatment. The simplified formula is θ=1.1(1/β-1)(K s +S)/KX 0, for petrochemical wastewater treatment K and K s equaled 0 185 and 154.2, respectively.展开更多
文摘AIM:To investigate the correlation between mitogen-activated protein kinase (MAPK) signal transduction pathway and multidrug resistance (MDR) in MGC803 cells.METHODS:Western blot was used to analyze the expression of MDR associated gene in transient vincristine (VCR) induced MGC803 cells, which were treated with or without the specific inhibitor of MAPK, PD098059.Morphologic analysis of the cells treated by VCR with or without PD098059 was determined by Wright-Giemsa staining. The cell cycle analysis was performed by using flow cytometric assay and the drug sensitivity of MGC803 cells which were exposed to VCR with or without PD098059 was tested by using MTT assay.RESULTS:Transient exposure to VCR induced P-gp butnot MRP1 or GST-π expression in MGC803 cells and the expression of P-gp was inhibited by PD098059.Apoptotic bodies were found in the cells treated with VCR or VCR+PD098059. FCM results indicated that more MGC803 cells showed apoptotic phenotype when treated by VCR and PD098059 (rate:31.23%) than treated by VCR only (rate:18.42%) (P<0.05).The IC50(284±13.2 μg/L) of MGC803 cells pretreated with VCR was 2.24-fold as that of negative control group (127±17.6μg/L) and 1.48-fold as that of the group treated with PD098059 (191±27.9μg/L).CONCLUSION:This study shows that the expression of P-gp can be induced by transient exposure to VCR and this induction can be prevented by PD098059, which can block the activity of MAPK. MAPK signal transduction pathway may play some roles in modulating MDR1 expression in gastric cancer.
文摘OBJECTIVE To investigate the effect of a specific inhibitor PD098059 of the extracellular-signal regulated protein kinase (ERK) pathway on the P-glycoprotein (P-gp)-mediated resistance of colon cancer cell lines SW480/VCR and CoLo205NCR.METHODS SW480NCR and CoLo205NCR cells were generated byexposuring SW480 and CoLo205 cells to vincristine (VCR) (30 ng/ml) for 72h, which resulted in a comparatively higher level of P-gp expression.Western blotting was used to analyze P-gp, MRP, LRP, GST-'rr and TOPOIIexpression after exposuring the SW480 and CoLo205 cells to VCR (30 ng/ml)for 72 hrs. P-gp and pERK1/2 expressions was analyzed in SW480NCR andCoLo205/VCR cells treated with or without the specific inhibitor of MEK,PD098059. The MTT assay was used to determine the susceptibility ofSW480NCR and CoLo205NCR cells to VCR, treated with or withoutPD098059.I^F.SULI"S The results showed that VCR induced a comparatively higher levelof P-gp expression in the cell lines, but not that of MRP, LRP, GST-n- orTOPOII. P-gp expression levels were depressed significantly in SW480/VCR and COLO205/VCR cells by the specific inhibitor of MEK, PD098059.The IC50 (248 +19.6 and 215 +10.7 ng/ml) to VCR of SW480/VCR andCoLo205/VCR cells exhibited a 2.16 and 2.03-fold higher resistancecompared to the negative control group (SW480 and CoLo205 cells)(115+15.6 and 106 +11.9 ng/ml), but a 1.35 and 1.21 -fold higher resistance thanthe group treated with VCR (30 ng/ml)+ PD098059 (184 + 21.8 and 177+19.4 ng/ml).CONCLUSION This study shows that the expression of P-gp can beinduced by exposuring cells to VCR, and that this induction can be reversedby inhibiting the ERK signaling pathway at the point of MEK by its specificinhibitor, PD098059. The ERK signal-transduction pathway may play a rolein modulating mdrl expression in colon cancer.
基金This work was partially supported by CNPq,FAPDF,Coordenação de Aperfeiçoamento de Pessoal de Nível Superior-Brasil(CAPES)-Finance Code 001US National Science Foundation(US NSF DMR-1104994 and CBET-1510121).
文摘The use of valley excitonic states of transition metal dichalcogenides to store and manipulate information is hampered by fast carrier recombination and short valley lifetime.We propose theoretically a scheme to overcome such an obstacle,by applying a tilted exchange field through the magnetic proximity effect on monolayer MoS_(2).While the in-plane component of the exchange field brightens the dark exciton by spin mixing,the out-of-plane field can effectively gate the emission with an ON/OFF ratio of 2700.Importantly,the brightening is valley selective,leading to nearly 100% valley and spin polarization at room temperature.The resulting strongly gateable dark-exciton emission with long lifetime and near unity valley polarization makes it convenient to manipulate the valley degree of freedom,which may offer new paradigm for information processing and transmission.
文摘本研究采用水热-冷冻干燥-煅烧的方法成功制备了铜掺杂硫化锡负载氧化石墨烯气凝胶(Cu x SnSO@GO),并采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和紫外-可见光反射分析(UV-vis DRS)对材料进行表征,研究了不同Cu掺杂量和不同反应时间对光催重整纤维素酶解液产乳酸的影响。结果表明,铜成功的掺入到SnS_(2)结构中,产生表面硫缺陷,改变了SnS_(2)的带隙,提高了SnS_(2)的光催属性。此外,煅烧工艺制备的Cu x SnSO@GO改善了光生电子和空穴的分离效率,显著提高了光催化效率。Cu x SnSO@GO在可见光照射下能够高效的光催重整纤维素酶解液产乳酸,当Cu掺杂量x=0.06反应时间为4 h时,Cu x SnSO@GO具有38.8%的最佳产率。Cu x SnSO@GO形成的表面硫空位、高吸收性、可调节的能带结构以及煅烧后形成的Cu x SnS_(2)-SnO 2异质结都有利于乳酸的选择性转化,这为研究生物质光催化重整的机理提供了一种新的途径。
文摘Based on the microorganism kinetic model, the formula for computing hydraulic retention time in a membrane bioreactor system (MBR) is derived. With considering HRT as an evaluation index a combinational approach was used to discuss factors which have an effect on MBR. As a result, the influencing factors were listed in order from strength to weakness as: maximum specific removal rate K , saturation constant K s, maintenance coefficient m , maximum specific growth rate μ m and observed yield coefficient Y obs . Moreover, the formula was simplified, whose parameters were experimentally determined in petrochemical wastewater treatment. The simplified formula is θ=1.1(1/β-1)(K s +S)/KX 0, for petrochemical wastewater treatment K and K s equaled 0 185 and 154.2, respectively.
