Objective To investigate the clinical application of ALT detection based on microtiter plate kinetic method in the au‐tomatic enzyme immunoassay system .Methods By beference to the IFCC recommended kinetic method ,microtiter plate kinetic method was established in the automatic enzyme immunoassay system of ALT detection .The linear ,intro‐batch and inter‐batch du‐plicability of the method were evaluated .ALT test results of 823 samples with microtiter plate kinetic method and automatic bio‐chemistry analyzer method were compared .Results Microtiter plate kinetic method had good linearity where ALT activity <303 U/L ,the intra batch and inter batch variation coefficients < 1/5TEa .The detection results of the clinical samples were correlated with the biochemical analyzer .Conclusion Microtiter plate kinetic method to detection ALT in the automatic enzyme immunoassay system is an ideal method for simultaneous detection of ALT and ELISA in large batch samples ,which is worth popularizing .

Objective To investigate the virulence role of ompT of Escherichia coli in the patho-genesis of neonatal meningitis .Methods Adhesive abilities of the parent strain E 44 and the isogenic ompT-deletion mutant strain ( E44 ∶ΔompT) to human brain microvascular endothelial cells were evaluated in in vitro model.Low-copy-number plasmid pST containing ompT locus and point mutant plasmid pST 85 were transferred into E44 ∶ΔompT to construct the complemented mutant strain , and its adhesive ability was ana-lyzed.Influences of ompT deletion on E44 strain in its ability of bacterial intestinal colonization and ability of penetrating the blood-brain barrier were determined . Results In comparison with the parent strain , E44 ∶ΔompT strain showed significantly impaired adhesive ability to human brain microvascular endothelial cells, which could be partly restored by inserting the complementary plasmids of pST and pST 85.Deletion of the ompT did not affect Escherichia coli K1 in normal intestinal colonization in in vivo model.E44 ∶ΔompT strain could induce bacteremia , which was similar to that induced by the parent strain , but its ability of crossing the blood-brain barrier was significantly declined .Conclusion The study demonstrate that ompT plays an important role as the virulence element of Escherichia coli in binding to brain microvascular endothe-lial cells and penetrating the blood-brain barrier .Further study should be performed to investigate the influ-ences of OmpT proteinase on the virulence of Escherichia coil.

Objective To construct a recombinant Escherichia coli ( E. coli) with surface-dis-played lead specific binding protein PbrR and to further study intestinal colonization by the recombinant bac-teria in mice and gastrointestinal tolerance of the bacterial surface-displayed PbrR. Methods Chimeric pro-tein Lpp-OmpA coding sequence was chemically synthesized and inserted into the expression vector pET-21a to construct the outer membrane display vector pLOA. PbrR coding sequence was also obtained by chemical-ly synthesis and inserted into pLOA to generate the outer membrane display plasmid pLOA-pbrr. E. coli BL21 (DE3)pLysS was transformed with pLOA-pbrr and induced by IPTG. The expressed recombinant proteins were analyzed by 15% SDS-PAGE and Western blot assay. Lead adsorption capacity of the cell surface-dis-played PbrR in the simulated intestinal juice and tolerance of the recombinant E. coli to simulated gastric juice were analyzed, respectively. KM mice were orally given the induced recombinant bacteria by gastric lavage for 7 consecutive days and then were continually fed until day 30. The contents of recombinant bacte-ria in stool samples were detected by dilution plate method on day 7, 15 and 30. The recombinant protein with His tag was detected by immunoblotting on day 7 and 15. Results Based on Lpp-OmpA, the PbrR outer membrane display vector was successfully constructed. The recombinant fusion protein Lpp-OmpA-PbrR-His tag was highly expressed in E. coli. The recombinant E. coli strains displaying PbrR on their outer membrane accumulated a significant level of Pb2+ in simulated intestinal juice. Moreover, those strains showed a tolerance to gastric acid in vitro and could colonize in the intestinal tracts of mice via oral infection. The surface-displayed recombinant fusion protein showed a better tolerance to the environment of digestive tract. Conclusion The recombinant E. coli strain displaying PbrR on its surface showed a stronger capabili-ty of lead accumulation from simulated intestinal environment and could colonize in the intestinal tracts of mice. The surface-displayed recombinant PbrR also showed a good tolerance to digestive juice. This study paved the way for further researches on the selective elimination of lead by biosorption based on animal mod-els.