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OBJECTIVE To investigate the effect of TiO2 nanoparticles on overcoming cancer multidrug resistance(MDR). METHODS: Doxorubicin-TiO2 nanoparticles(DTN) were prepared, the K562/DOX cells were chosen as the model cells. And doxorubicin solution(F-DOX) and doxorubicin liposomes(DOX-L) were also prepared as the control. The MTT assay were measured, and the amount of doxorubicin in the K562/DOX cells at different time were determined by HPLC. The P-gp expression were detected by flow cytometry. RESULTS: The MTT assay shows that IC50 of group DTN were lower than that of group F-DOX. The uptake test shows that amount of doxorubicin in K562/DOX cells of group DTN was 1.23 times of group DOX-L when in 4 h, and the efflux test shows that amount of doxorubicin in K562/DOX cells was 1.18 times of group DOX-L. The flow cytometry result revealed that the effect of TiO2 nanoparticles on overcoming MDR maybe through down-regulating the expression of P-gp in K562/DOX cells. CONCLUSION: The TiO2 nanoparticles are a new inorganic materials-based nanoparticles which promising approach to overcome MDR.
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OBJECTIVE: To investigate the synergetic effect of schisandrin B and liposomes on overcoming multidrug resistance(MDR). METHODS: Co-delivery of doxorubicin and schisandrin B by liposome(DS-L) were prepared, and doxorubicin solution(F-DOX), schisandrin B and doxorubicin mixture(Sch B+DOX), doxorubicin liposomes(D-L), doxorubicin liposomes and schisandrin B mixture(D-L+Sch B), verapamil and doxorubicin mixture(Ver+DOX) were also prepared as the control. The MTT test were measured, and the amount of doxorubicin in the K562/DOX cells at different time were determined, and time course of uptake and efflux were drawn. RESULTS: The MTT test shows that the resistance factor(RF) of group DS-L were 1.68, 14.52 and 1.42 times of group Sch B+DOX, group D-L and group D-L+Sch B respectively. The uptake test shows that amount of doxorubicin of K562/DOX cells in group DS-L was 1.30 and 1.21 times of that in group D-L and group Sch B+DOX respectively. And the efflux test shows DS-L could delay doxorubicin efflux from K562/DOX cells. CONCLUSION: The co-delivery of chemotherapeutics and P-gp inhibitors schisandrin B by liposome is a promising approach to overcome MDR. And there is a synergistic effect between liposome and schisandrin B to overcome MDR.
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Multidrug resistance (MDR) is one of the major obstacles for successful chemotherapy in cancer. Inorganic material-based nanoparticles provide a novel choice to effectively circumvent the intrinsic drawbacks of traditional organic materials in overcoming the multidrug resistance (MDR) of cancer cells due to their unique structural and compositional characteristics, for example, high stability, large surface area, tunable compositions, abundant physicochemical multifunctionalities, and specific biological behaviors. In this work, the recent advances of inorganic materials-based nanoparticles to overcome MDR of cancer cells were reviewed. And the advantage and mechanism of inorganic materials-based nanoparticles to overcome MDR were summarized. The recent development of inorganic materials-based nanoparticles (mesoporous SiO2, Au, TiO2, magnetic Fe3O4, Ag, combinations of inorganic materials-based nanoparticles with traditional overcoming MDR strategy etc.), to overcome the MDR were also discussed. And the future developments of these inorganic materials-based nanoparticles are suggested. These elaborately designed inorganic materials-based nanoparticles offer an unprecedented opportunity and show the encouraging bright future for overcoming the MDR of tumors.
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AIM: To investigate the effect of problem - based learning ( PBL) used in the teaching of medical students'evidence-based medicine ( EBM) . METHODS: Five classes ( total 147 students ) were randomly selected as experimental ( PBL ) group, at the same time, another 5 classes ( total 149 students ) were also randomly selected as control group, using traditional teaching method ( lecture-based learning, LBL ) in 2010 grade. The final examination scores of the experimental group were compared with control at the end of term. In addition, all students were interviewed using self -administered questionnaire to obtain their evaluation for PBL practice. SPSS13. 0 software was used for statistical analysis. RESULTS: The homogeneity test in baseline survey showed that the basic characteristics between the two groups of students were no significant differences, and were comparable (P>0. 05). Final exam results showed that in addition to the scores of the EBM basic knowledge indicated no significant difference between two groups of students (P>0. 05), for the 5 steps of EBM procedure, namely, asking questions, finding the best evidence, evaluating the evidence, using and practicing the evidence, re - evaluating the evidence, and the total scores between the two groups, there were significant statistically differences (P0. 05) in aspects of better understanding classroom knowledge, improving language expression ability, and writing skill exercises. And other residual items had a significant difference ( PCONCLUSION: PBL teaching mode can effectively improve teaching effectiveness and the quality of EBM teaching, so the this teaching mode is worth further popularizing.
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<p><b>OBJECTIVE</b>To develop an RP-HPLC method for simultaneous determination of 5 constituents in Fructus Cnidii.</p><p><b>METHOD</b>Analysis was performed on an Alltech C18 (4.6 mm x 250 mm, 5 microm) column. The mobile phases were acetonitrile water and acetic acid with gradient elution. The flow rate was 1 mL x min(-1). The monitoring wavelength was 325 nm and 245 nm. The column temperature was 40 degrees C.</p><p><b>RESULT</b>The linear response ranges were 1-20 microg x mL(-1) (r = 0.999 9) for xanthotoxin, 1-20 microg x mL(-1) (r = 0.999 9) for isopimpinellin, 11-20 microg x mL(-1) (r = 0.999 8) for bergapten, 100-1 200 microg x mL(-1) (r = 0.999 7) for imperatorin, 100-2 000 microg x mL(-1) (r = 0.999 9) for osthole. The average recoveries were all above 95%.</p><p><b>CONCLUSION</b>The method is simple, sensitive and accurate with good reproducibility.</p>