BACKGROUND:Compared with single or composite biomolecular materials, decellulazied matrices are more biomimetic to natural ectocytic surroundings. So cel-secreted extracellular matrix is paid more and more attention in the field of tissue engineering, and the composition of these matrices are influenced by decellulezired preparation methods more or less. But there are few studies about the biological effect of different decellulazried methods on the extracellular matrix. OBJECTIVE:To investigate the composition of cel-secreted extracellular matrices in vitro by different decellularizing methods and their effects as surface modification on cytobiological reaction. METHODS:After the treatment of different decellularizing methods (freeze/thaw cycles, trypsin, weak alkal, detergents), the extracellular matrix was obtained and grouped into four kinds. The biological composition of the extracellular matrix was determined by ELISA assay. Then osteoblasts were seeded onto the four kinds of extracellular matrix surfaces. cells cultured normal y served as controls. The effect of extracellular matrix coatings on cellgrowth and differentiation were determined by MTT test and alkaline phosphatase activity test. RESULTS AND CONCLUSION:The residual components were the most in the freeze-thaw group, fol owed by the detergent and weak alkal groups, and the least in the trypsin group. Compared with the control group, the absorbance value of cells were lower in the freeze-thaw and detergent groups at days 3, 5, 7 after inoculation (both P<0.05);the alkaline phosphatase activity was lower in the trypsin group at days 5, 7 after inoculation (P<0.05), in the weak alkal group at 7 days after inoculation (P<0.05), and in the detergent group at days 3, 5, 7 after inoculation (P<0.05). Therefore, we can harvest more extracellular matrices by the freeze-thaw method, and the extracellular matrix coating synthesized by the freeze-thaw method is more helpful for cellgrowth than others.

Objective To investigate the operation timing of laparoscopic cholecystectomy (LC)after endoscopic sphincterotomy (EST).Methods A total of 240 patients with cholecystolithiasis and choledocholithiasis received EST combined with LC.They were divided into 3 groups by random digits table method with 80 cases each:3 days after EST(group A),7 days after EST(group B),and 30 days after EST (group C).Intraoperative and postoperative clinical data were compared among three groups.Results The operation time of LC in group B [(52.5 ± 6.4) min] was longer than that in group A and group C [(35.8 ± 5.7),(34.6 ± 2.6) min],and there was significant difference (P ＜ 0.01).The intraoperative conversion rate in group B [10.0 ％ (8/80)] was higher than that in group A and group C [1.3 ％ (1/80),1.3 ％ (1/80)],and there was significant difference (P ＜ 0.05).The amount of bleeding in group B [(51.7 ± 4.8) ml] was larger than that in group A and group C [(27.9 ± 6.4),(28.2 ± 3.6) ml],and there was significant difference (P ＜ 0.01).The cost of hospitalization in group C [(15 361.2 ± 1 007.8) yuan] was more than that in group A and group B [(10 085.1 ± 695.4),(10 632.4 ± 855.9) yuan],and there was significant difference (P＜ 0.01).Conclusion LC performed 3 days after EST can reduce the operation difficulty and conversion rate,and shorten the operation time,and this modality is safe and effective.

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