In recent years, Bacterial resistance is more and more serious for the irrational use of antibiotics produces resistant strains and other reasons. Human are trying to solve the problem from different ways, including the study of antimicrobial peptides. Defensin is one of the most important of antimicrobial peptides. A novel antimicrobial peptide, human beta-defensin 3, was isolated and demonstrated a salt-insensitive broad spectrum of potent antimicrobial activity against many potentially pathogenic microbes. The total RNA was extracted from human tonsil and the hbetaD-3 specific cDNA sequence was amplified with RT-PCR. After sequenced, the target DNA fragment was cloned into pQE-80L vector together with the DNA fragment encoding carrier protein DHFR. The recombinant vectors were transformed into E. coli M15 and the expression was induced based on the optimal values of the IPTG concentration incubation temperature and induction time determined in the previous section. The expressed proteins were analyzed by SDS-PAGE and Western-blotting. The mass of the recombinant protein was about 40% of total bacteria protein. Isolate and purify the target protein. The recombinant hbetaD-3 fusion proteins possess the antimicrobial activity to staphylococcus aureus, multiresistant staphylococcus aureus (only vancomycin-sensitive) and Candida albicans in the assay of drug susceptibility. Advanced study can be continued based on our experiments.
Cloning, Molecular ; Escherichia coli ; genetics ; Plasmids ; Recombinant Fusion Proteins ; biosynthesis ; isolation & purification ; pharmacology ; Staphylococcus aureus ; drug effects ; Tetrahydrofolate Dehydrogenase ; genetics ; beta-Defensins ; biosynthesis ; genetics ; pharmacology

Stable transformants for mammalian cells from gene transfer often show extreme variability in expression of the introduced transgene. This occurs from the highly variable number of copies integrated into the genome and from position effects on gene expression due to random integration. We constructed engineered CHO strains that can be used for high-level production of foreign proteins by gene-targeting. After transfecting dihydroforate reductase (DHFR)-deficient CHO cells with a newly screening vector plasmid pMCEscan, which carrying a FRT-neo*-IRES-k2tPA fusion gene and a DHFR gene, we screened colonies by k2tPA expression level. We selected 7 clones that expressed high level of k2tPA and carried one copy of the plasmid in their chromosomes. These clones showed in high level k2tPA production without amplification. So we targeted reporter gene (k2tPA) to test the basal expression ability of these cells clones. The clone, 8-1, showed the same effect to high base expression level. In this clone, the FRT-neo*-IRES-tPA gene was integrated at a transcription-active, DHFR-mediated, gene-amplifiable locus in the chromosomes. A gene-targeting vector, carrying a FRT-fused hygromycin-resistance gene, was constructed to target desired genes in chromosomal FRT by FLP recombinase-mediated site-specific recombination. Using this cell-vector system, we could reproducibly obtain high producers of recombinant proteins by gene-targeting and gene amplification. Using the site-specific integration CHO/dhfr- cell line 8-1, the expression level of k2tPA could amount to 17.1 microg/10(6) cell x 24 h.
Animals ; CHO Cells ; Cricetinae ; Cricetulus ; DNA Nucleotidyltransferases ; genetics ; Gene Amplification ; Gene Targeting ; methods ; Genes, Reporter ; Genetic Engineering ; methods ; Recombinant Proteins ; biosynthesis ; genetics ; Tetrahydrofolate Dehydrogenase ; genetics

The precise mechanism whereby granulocytes proliferate when haematopoietic colony stimulating factors (CSFs) are used in neutropenic cancer patients is poorly understood. The purpose of this study was to investigate whether these cytokines bring about leucocyte proliferation by increasing the levels of multiple forms of dihydrofolate reductase (DHFR). Blood samples were collected from 36 cancer patients (25 males and 11 females) with chemotherapy-induced neutropenia. One sample of blood from each patient was obtained before therapy either with CSF, such as granulocyte colony stimulating factor (G-CSF) and granulocyte-macrophage colony stimulating factor (GM-CSF) or with placebo, and another one at the time of resolution of neutropenia. Peripheral blood leucocytes in these blood samples were counted, separated and lysed. From lysates, cytoplasmic samples were prepared and analyzed for active DHFR by a methotrexate-binding assay and for total immunoreactive DHFR by an enzyme linked immunosorbent assay. The increase in total leucocyte count (TLC) was most prominent (P < 0.005) in the CSF group and less so (P < 0.05) in the placebo group. The mean +/- SD concentration values of active DHFR before and after stimulation with GM-CSF found were to be 0.34 +/- 0.4 ng/mg protein and 0.99 +/- 0.82 ng/mg protein, respectively, and in the group treated with G-CSF, 0.24 +/- 0.32 ng/mg protein and 1.18 +/- 2.4 ng/mg protein, respectively. This increase in active DHFR after stimulation with CSF was statistically significant (P <0.05). Similarly, concentration values of immunoreactive but nonfunctional form of DHFR (IRE) were 110 +/- 97 ng/mg protein and 605 +/- 475 ng/mg protein before and after stimulation with GM-CSF, and 115 +/- 165 ng/mg protein and 1,054 +/- 1,095 ng/ mg protein before and after stimulation with G-CSF. This increase in concentration of IRE after stimulation with GM-CSF or G-CSF was statistically significant (P < 0.005). In the control group, there was an increase in the concentration of both active DHFR and IRE after treatment with placebo. However, this was not statistically significant. Resolution of neutropenia was quicker in the groups treated with CSF compared to the control group. Results of this study indicate that colony stimulating factors (G-CSF and GM-CSF) induce white cell proliferation by increasing the levels of multiple forms of DHFR.
Adolescence ; Adult ; Cell Division/drug effects ; Child ; Female ; Granulocyte Colony-Stimulating Factor/therapeutic use ; Granulocyte Colony-Stimulating Factor/pharmacology* ; Granulocyte Colony-Stimulating Factor/adverse effects ; Granulocyte-Macrophage Colony-Stimulating Factor/therapeutic use ; Granulocyte-Macrophage Colony-Stimulating Factor/pharmacology* ; Granulocyte-Macrophage Colony-Stimulating Factor/adverse effects ; Human ; Isoenzymes/metabolism ; Isoenzymes/biosynthesis ; Leukocyte Count ; Leukocytes/pathology ; Leukocytes/enzymology ; Leukocytes/drug effects ; Male ; Middle Age ; Neoplasms/enzymology ; Neoplasms/drug therapy ; Neoplasms/blood* ; Neutropenia/metabolism* ; Neutropenia/chemically induce ; Neutropenia/blood ; Tetrahydrofolate Dehydrogenase/metabolism* ; Tetrahydrofolate Dehydrogenase/biosynthesis