ABSTRACT
In order to obtain the serotype distribution of E.coli from duck and to screen the vaccine bacterial strains,the serotype identifications and biological characteristics of E.coli were analyzed in recent years from Shandong,Hebei and other areas of commercial duck field;selections of vaccine strains were detected by the virulence and immunogenicity.Totally 44 isolated bacterial strains of E.coli from duck were identified to a total of six serotypes:O78,O93,O76,O2,O92 and O32.The O78 serotype was the dominant serotype,accounting for 56.8％ (25/44);O93 serotype for 15.9％ (7/44) according to bacterial Oantigen typing.The strain SD (O78 serotype) was confirmed to have strong virulence and good immunogenicity.The O78,O93 and O76 are the dominant serotypes of duck E.coli in the study areas.The SD strain could be used as the candidate for the next development of inactivated vaccine.
ABSTRACT
Objective:To study the effects of genistein (GE) and quercetin (QU) on proliferation and collagen synthesis of mouse fibroblast NIH3T3 cells.Methods:Cell proliferation was measured by crystal violet staining assay.Collagen synthesis was determined by 3H proline incorporation assay.Results:GE (25 70 ?mol?L -1 ) and QU (6.25 50 ?mol?L -1 ) concentration dependently reduced the serum driven increase of cell proliferation and collagen synthesis.GE and QU also attenuated platelet derived growth factor (PDGF) driven proliferative activity and transforming growth factor ?1 (TGF ?1) driven collagen synthesis.Conclusion:GE and QU can inhibit mouse fibroblast NIH3T3 cell proliferation and collagen synthesis in vitro .
ABSTRACT
Triptolide (TL) is a major active component extracted from Chinese traditional herb Tripteryginm wil-fordii Hook. In this article, the effects of TL on mixed lymphocyte culture (MLC),suppressor T cell(Ts) activity, delayed type hypersensitivity (DTH) reaction, IL - 2 secretion activity and Th/Ts ratio were evaluated, In vitro TL 0. 5~10 ?g ? L-1suppressed one-way MLC,Lymphocytes induced in first MLC with TL of 5,10 ?g ? L-1 suppressed the second MLC after irradiation with 3000 rad 60Co source. This suggests that TL may induce Ts cell-s. In vivo, DTH reaction sensitized to dinitrofluo-robenzene (DNFB) monitored by the increase in weight of the ears challenged with antigen was suppressed by TL at doses of 0. 12 to 0. 50 mg ? kg-1(ip,qd?5) and the IL -2 activity secreted by spleen cells of these mice was inhibited at doses of 0. 25 and 0. 5 mg ? kg-1. TL 0. 25, 0. 5 mg ? kg-1(ip,qd?8) also had prominent suppres-sive effects on enhanced DTH reaction which was induced by cyclophosphamide(250 mg ? kg-1,ip). Th/Ts ratio of mouse thymus cells were reduced after given 0. 25 mg ? kg-1 of TL for 5 consecutive days. The above-mentioned data suggest that TL has suppressive effects on cellular immunity function and the suppressive mechanism may be related to the suppression of Th cells and IL-2 secretion activity and the induction of Ts cells.