ABSTRACT
<p><b>OBJECTIVE</b>To establish a modified method for microculturing whole human blood for cytogenetic analysis.</p><p><b>METHODS</b>A novel tube rack was designed to overcome the drawbacks of directly culturing the cells within centrifuge tubes. The fractions of human plasma, human serum and two commercial fetal bovine sera were analyzed with 15% sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The influence of adding 0%, 5%, 10%, 15%, 20%, 25% and 30% autologous plasma to the culture on lymphocyte transformation rate and mitotic index (MI) was examined.</p><p><b>RESULTS</b>The SDS-PAGE analysis showed a significant difference between commercial fetal bovine sera, and that the components of human plasma were similar to those of fetal bovine serum. The value of MI in lymphocyte was evidently increased along with addition of autologous plasma. However, this has exerted no significant effect on the transformation rate. With the addition of 10% autologous plasma, the MI value has become much higher than the conventional method.</p><p><b>CONCLUSION</b>A modified method was established by application of a novel tube inclined rack and optimization of whole blood inoculation. This method is easier and cheaper, and is suitable for application in clinical practice.</p>
Subject(s)
Adolescent , Adult , Female , Humans , Male , Cell Culture Techniques , Methods , Cytogenetics , Lymphocytes , Mitotic IndexABSTRACT
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.
ABSTRACT
Objective To study the effect of DNA damage induced by H2 O2 on the micronucleus frequency in lymphocytes. Methods Resting lymphocytes were treated with different levels of H2 O2 (10,50,100,1 000 μmol/L).1 000 μmol/L H2 O2 was added into mitogen-stimulated lymphocyte cultures at different time intervals.Then micronucleus rate was examined by the conven-tional culture method.Results There was no significant change of the micronucleus frequency in the experimental groups.Conclu-sion H2 O2 could induce lymphocyte DNA damage rapidly,but exerts no effect on the formation of micronuclei,which may be relat-ed to the type of DNA damage and rapid DNA repair.