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Objective To investigate the effect of different concentrations of magnesium-calcium alloy extract on the expression of matrix metalloproteinase-9 (MMP9) and tissue inhibitor of metalloproteinase-3 (TIMP3) in human colonic epithelial NCM460 cells.Methods The different concentrations of extracts (the volume fraction was 10％,50％ and 100％ respectively) were made with magnesium-calcium alloy.The 5 × 106 L-1 NCM460 suspension was randomly divided into control group,experimental group 1,experimental group 2 and experimental group 3.The cells in the control group were cultured by 2 000 μL high glucose Dulbecco's modified Eagle's medium (containing 10％ volume fraction of fetal bovine serum).The cells in the experimental group 1,2 and 3 were cultured by 2 000 μL magnesium-calcium alloy extract with volume fraction of 10％,50％ and 100％ respectively.The expressions of MMP9 and TIMP3 mRNA in NCM460 cells was detected by real-time fluorescence quantitative polymerase chain reaction,and the expression of MMP9 and TIMP3 protein in NCM460 cells was detected by Western blot at after one,three and five days of cultivation respectively.Results The expression of MMP9 mRNA and TIMP3 mRNA in NCM460 cells of the experimental group 1,2 and 3 was significantly lower than that in the control group after one day of cultivation (P ＜ 0.05).After three and five days of cultivation,the expression of MMP9 mRNA in NCM460 cells of the experimental group 1 was significantly lower than that in the control group (P ＜ 0.05),but the expression of MMP9 mRNA in the NCM460 cells of the experimental group 2 and 3 was significantly higher than that in the control group and the experimental group 1 (P ＜ 0.05).The expression of MMP9 mRNA in NCM460 cells of the experimental group 3 was significantly higher than that in the experimental group 2 after five days of cultivation (P ＜ 0.05).The expression of MMP9 mRNA in NCM460 cells of the experimental group 1,2 and 3 after three and five days of cultivation was significantly higher than that after one day of cultivation(P ＜ 0.05).There was no significant difference in the expression of MMP9 mRNA in NCM460 cells of the experimental group 1 between three and five days of cultivation (P ＞ 0.05).The expression of MMP9 mRNA in NCM460 cells of the experimental group 2 and 3 after five days of cultivation was significantly higher than that after three days of cultivation(P ＜ 0.05).The expression of TIMP3 mRNA in NCM460 cells of the experimental group 2 and 3 was significantly higher than that in the experimental group 1 after one day of euhivation (P ＜ 0.05).After three days of cultivation,the expression of TIMP3 mRNA in NCM460 cells of the experimental group 1,2 and 3 was significantly lower than that in the control group (P ＜ 0.05);the expression of TIMP3 mRNA in NCM460 cells of the experimental group 2 was significantly lower than that in the experimental group 1 and 3 (P ＜ 0.05).After five days of cultivation,the expression of TIMP3 mRNA in NCM460 cells of the experimental group 1,2 and 3 was significantly higher than that in the control group (P ＜ 0.05).The expression of TIMP3 mRNA in NCM460 cells after three and five days of cultivation was significantly higher than that after one day of cultivation (P ＜ 0.05),and the expression of TIMP3 after five days of cultivation was significantly higher than that after three days of cultivation in the experimental group 1 (P ＜ 0.05).The expression of TIMP3 mRNA in NCM460 cells after three days of cultivation was significantly lower than that after one day of cultivation (P ＜ 0.05),and the expression of TIMP3 after five days of cultivation was significantly higher than that after one and three days of cultivation in the experimental group 2 (P ＜ 0.05).The expression of TIMP3 mRNA in NCM460 cells after five days of cultivation was significantly higher than that after one and three days of cultivation in the experimental group 3 (P ＜ 0.05).After five days of cultivation,there was no significant difference in the expression of MMP9 protein in NCM460 cells between the experimental group 1 and control group (P ＞ 0.05),the expression of MMP9 protein in NCM460 cells of the experimental group 2 and 3 was significantly higher than that in the control group and the experimental group 1 (P ＜ 0.05),but there was no significant difference in the expression of MMP9 protein in NCM460 cells between the experimental group 2 and 3 (P ＞ 0.05).After five days of cultivation,the expression of TIMP3 protein in NCM460 cells of the experimental group 1,2 and 3 was significantly higher than that in the control group (P ＜0.05);but there was no significant difference in the expression of TIMP3 protein in NCM460 cells among the experimental group 1,2and 3 (P ＞ 0.05).Conclusions The high concentration of magnesium-calcium alloy extract has certain influence on the expression of MMP9 and TIMP3 gene in NCM460 cells,which may lead to the early inflammatory reaction,and the mechanism may be related to the calcium ion concentration in the extract.
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<p><b>BACKGROUND</b>To isolate and identify pathogen of atypical pneumonia in Guangdong.</p><p><b>METHODS</b>Pathogens were isolated from variety of samples collected from atypical pneumonia patient by using MDCK cells, and identified with serological and molecular methods.</p><p><b>RESULTS</b>A novel coronavirus was isolated from patients with atypical pneumonia, from which an RNA fragment of 279 nt was amplified by nested RT-PCR. And sequence assay showed that only 39-65 percent of sequence of the virus was homogenous to known coronavirus, but almost 100% homogenous (with one base exception, 12a to t) to SARS-associated coronavirus isolated from patients outside Guangdong, such as in Beijing, Hong Kong, Taiwan, Germany, Italy and so on. Indirect immunofluorescence test showed a specific antigen-antibody reactivity between the coronavirus and convalescent-phase sera of SARS patients.</p><p><b>CONCLUSION</b>The pathogen of the atypical pneumonia in Guangdong province was a novel type of coronavirus, which could be isolated by using MDCK cells.</p>