ABSTRACT
Objective To explore the inhibitory effect of astragalus polysaccharide (APS) on the proliferation of human erythroleukemia K562 cells and its mechanisms.Methods After K562 cells (purchased from Shanghai cell bank of chinese academy of science) were treated with different concentrations (0 mg/L,100 mg/L,200 mg/L and 400 mg/L) of APS.The influences of APS on the growth rate,doubling time and cell cycle distribution of K562 cells were observed by methyl thiazolyl tetra-zolium assay (MTF) and flow cytometry,respectively.Furthermore,the reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting assay were used to detect the expressions of Cyclin A,Cyclin B,Cyclin E and p21 gene at the mRNA and protein levels,respectively.Results MTT assay findings showed that,compared to the control group (0 mg/L APS),growth rates of K562 cells treated with 100 mg/L,200 mg/L and 400 mg/L APS decreased significantly (all P ＜ 0.01),and the doubling times lengthened significantly (all P ＜ 0.01).Flow cytometry findings revealed that,compared to the control group,the G1 phase cells in K562 cells of APS group increased significantly (P ＜0.01),while the S and G2/M phase cells decreased significantly (all P ＜ 0.01).RT-PCR and Western blotting results indicated that Cyclin B and Cyclin E expression of K562 cells at the mRNA and protein levels in the APS group were significantly lower than those of the control group(all P ＜ 0.01),whereas p21 expression was significantly enhanced at mRNA and protein levels (P ＜ 0.01),and Cyclin A expression was not significantly different at mRNA and protein levels between the 2 groups (all P ＞ 0.05).Conclusions APS could inhibit the proliferation of human erythroleukemia K562 cells.APS could inhibit the proliferation of K562 cells by down-regulating the expression of Cyclin B and Cyclin E and up-regulating the expression of p21.
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Objectives To assess the efifcacy of nasal bilevel positive airway pressure (nBiPAP) in preventing extuba-tion failure of neonatal respiratory distress syndrome (RDS) in premature infants. Methods Premature infants (≤32 weeks) diagnosed as RDS and treated with mechanical ventilation, admitted to the neonatal intensive care unit from January 2011 to June 2012, were enrolled in the prospective controlled trial. Fifty-six infants receiving non-invasive ventilation due to unrelieved expiratory dyspnea after the ifrst extubation were selected, and were randomly divided into nBiPAP group (n=27) and nCPAP group (n=29). Blood gas analysis before and after non-invasive ventilation, the failure rate of non-invasive venti-lation in seven days and the incidence of various complications were compared between two groups. Results The blood gas analysis for the ifrst time after extubation suggested that infants treated with nBiPAP had a higher PaO2 level ((58.7±6.3) vs. (55.1±5.9) mmHg, P<0.05) and lower PaCO2 level ((46.4±4.9) vs. (49.9±5.0) mmHg, P<0.05) than those treated with nCPAP. Infants treated with nBiPAP had lower incidence of extubation failure in seven days than infants treated with nCPAP (7.4%vs. 31.0%, P=0.042). The incidence of complications between two groups was similar. Conclusions nBiPAP is safe and fea-sible for preventing extubation failure in preterm infants≤32 weeks with RDS and is more effective than nCPAP.
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Purpose:To constract and identify eukaryotic expression vector carrying human VEGF cDNA to cure human ovarian cancer with antiangiogenesis method. Methods:Reverse transcription PCR for VEGF, VEGF was inserted into eukaryotic exprssion vector pcDNA3 to construct pcDNA3-VEGF(-), in which restriction enzyme analysis was used to confirm the reverse orientation fo the VEGF cDNA from the individual transformants. The vector was transfected into human ovarian cancer cell HO-8910 and the positive clone was screened by G418,VEGF expression was confirmed by RNA dot blot. The VEGF expression of HO-8910 cells before or after transfection was detected by Western blot and imunofluorescence.The biological characteristics of HO-8910 cells before and after transfectionwas inspected. Results: VEGF gene was obtained by RT-PCR, the pcDNA3-VEGF(-) vector was obtained. VEGF expression was blocked by anisense VEGF RNA. The clone formation ability of singal cell was decreased after transfected, G 1 phase cells were increased and S Phase celIs were decreased in cell cycle. The proliferation of HO-89l0 cell was reduced. The formation rate and growth speed of xengrafted tumor slowed down. Conclusions:The successful construction of antisense VEGF eukaryotic expression vector is of significance for ovarian cancer-specific antisense gene therapy.
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Objective To investigate the effects of different astragalosides(AST) and hydro-soluble astragali polysaccharide(APS) of Astragalus membranaceus on inducing erythroid differentiation of human leukaemic K562 cells.Methods APS and AST were extracted by alcohol or water from Astragalus membranaceus.K562 cells were treated with APS,AST and sodium butyrate(BA) respectively.The proportion of benzidine-positive cells was examined after 1-4 days culture.MTT assay was performed for evaluating the proliferation effects of APS,AST and BA on K562 cells.Results The percentages of benzidine-positive cells induced by APS,AST and BA were 13.2%,2.9% and 17.5%,respectively.The kinetic characteristics of K562 cells induced by different levels of APS(1,2,4,8mg/ml) indicated that 4 mg/ml APS was sufficient to induce K562 cells to turn to be benzidine-positive.The results suggested that APS,other than AST,could induce the K562 cells towards erythroid differentiation.Compared with BA,the percentage of benzidine-positive cells induced by APS was lower at 24h,48h and 72h(F=237.44,P=0.00),while the total number of benzidine-positive cells was higher at 96h(F=322.25,P=0.00).The results of MTT assay for Absorbance(A) showed that APS and AST had no inhibitory effects on growth of K562 cells(P=0.28,P=0.11),while BA showed an obvious inhibitory effect on K562 cells(P=0.00).Conclusion Astragalus membranaceus has pharmacological effects to induce the K562 cells towards erythroid differentiation,and its valuable constituents are contained in hydro-soluble astragali polysaccharide(APS).The induction of differentiation is most evident with a dosage of 4 mg/ml APS.The cell growth curve reveals that APS has no inhibitory effect on K562 cells.