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Objective To study the increased radiosensitivity of tumor cells by triterpene acids of loquat leaf (TAL) and mechanism.Methods C6 and MG63 cells were pretreated by TAL,and then were exposed to X-rays at 1,2,3,5,7 Gy.Clonogenic assay was used to evaluate those tumor cells survival fraction (SF) to calculate the sensitization enhancement ratios (SER) of TAL.The cellular micronuclei ratios of tumor cells were analyzed by micronuclei assay.Additionally,the changes of Rad51 and XRCC4 levels were observed by RT-PCR and Western blot.Results D0 values were decreased to 1.31 and 2.85 Gy in C6 and MG63 cells by TAL pretreatment respectively.The SER value of the effect of TAL on C6 and MG63 cells was 1.73 and 2.04,respectively.There was a statistical difference in the cellular micronuclei ratios between tumor cells with TAL above 2 Gy and those without TAL (C6:t =-8.372--2.476,P ＜0.05 ; MG63:t =-4.03--2.557,P ＜ 0.05).TAL attenuated the expression of XRCC4 at transcriptional and translational level,but not for Rad51,a key gene in homologous recombination repair (HRR).Conclusions TAL pretreatment could increase the lethal effect of X-rays on tumor cells in vitro.The mechanism might be involved in the inhibition of non-homologous end joining (NHEJ).
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Objective To investigate the radiosensitization effect and underlying mechanism of Paeonol on human lung adenocarcinoma cell line A549 in vitro. Methods Cells were assigned to following groups:control,Paeonol alone,irradiation alone,Paeonol combined with irradiation.The effect of Paeonol on cell proliferation was evaluated by the MTT assay. Clonogenic assay was performed to measure the radiosensitization effect of Paeonol under three concentrations around 20％ IC50.Cell apoptosis was determined by TUNEL assay and flow cytometry (FCM).The expression of Survivin protein was analyzed by Western blot.Results Cell growth was inhibited by Paeonol in a dose-dependent manner and the IC50 of Paeonol was (25.2 ± 2.1 ) mg/L. Clonogenic assay showed that Paeonol could markedly enhance cell radiosensitivity and the sensitizing enhancement ratio (SER) was 1.29.After the pretreatment of Paeonol with different concentrations,radiation-induced apoptosis increased with the doses at 24,48,and 72 h post-irradiation ( t =4.95,3.03,3.78,4.59,2.88,3.70,5.54,P ＜ 0.05 ). Moreover,the protein expression of Survivin was obviously down-regulated by 22.6％ - 56.7％ ( t =4.15,7.30,13.47,P ＜0.05 ) due to the treatment of Paeonol.When the Paeonol-treated cells were further irradiated with 6 Gy X-rays,the expression of Survivin was reduced to 22.2％ - 69.4％ ( t =4.30,8.36,16.34,P ＜ 0.05 ).Conclusions Paeonol had radiosensitization effect on the human lung adenocarcinoma cell line A549 in vitro,where the down-regulated Survivin protein might be involved.
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It has been indicated that there are a large number of natural active compounds generating the radiosensitizing effect on tumor.According to diverse molecular mechanism,these compounds may enhance the radiotherapeutic efficacy via enhancing the radiosensitivity of tumor.Studying the radiosensitization mechanism and classifying the natural compounds with the potentiality of development into clinical radiosensitizers can provide certain ideas for further research and development of natural radiosensitizers.
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Based on the philosophical thinking of entropy and dissipative structures theory,it is of an important significance to solve the problems existing in medical education by combining it with humanistic education.In present paper,the comparison of Chinese-American medical humanity education and the influence of medicine development by those differences are shown according to the analysis of entropy and dissipative structures theory.Furthermore,the deficiencies of Chinese medical humanity education are demonstrated,and some primary methods solving these problems are put forward as well.
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0.05). Conclusions In human liver microsome system in vitro,CYP1A2,2B6 and CYP2A6 contribute to the metabolism of 629.It is very important for bioreduction drugs design and development,and provide the basic experimental and theoretical profiles for extensive application in clinic.