ObjectiveTo explore the impact factors of medical graduates being employed at grass roots. Analysis may contribute to the adjustment and improvement of control policy. Methods1,000 students in Guangzhou Medical University were randomly sampled, and 946 valid questionnaires were being collected. Factor Analysis was adopted to extract component. Extraction method was Principal Component Analysis and rotated component.Components were used as independent variables in the Logistic Regression. The variable Y ( Willing to be employed at Grass Roots or not ) as the dependent variable. Adopted Logistic Regression analysis was made to explore impact factors of medical Graduates employed at Grass Roots. ResultsAccording to the Eigenvalues and Rotation Sums of Squared Loadings, 5 Components were extracted. The sorted descending is 'for grass-roots development', 'basic working conditions and benefits','the parent's attitude towards my career development' and 'family economic conditions'. ConclusionImpact factors can be reflected more objectively by using factor analysis elimination co-linearity in the original variables.

Strengthening assistant team is the important guarantee and effective mechanism to enhance and improve the mental and political education of college students and to maintain the stability of university.The article,through analyzing the status quo of building assistant team,puts forward pertinently some thoughts on the priority of system and construction of high-level staff of assistants.

The contemporary university students as a special political groups,can have a significant impact on social and political life. Comprehensive understanding of the ideological and political behavior of contemporary college students is to study the characteristics of the ideological and political behavior of college students. The study has found that the ideological and political behavior of contemporary college students shows the following main features such as the rationality of ideological and political behavior,confusion and utilitarian,as well as the diversity of political participation means.

Objective To analyze the immunogenicity of selected B-cell epitopes of Epstein-Barr virus (EBV) latent membrane protein-2 (LMP2). Methods Three potential dominant B-cell epitopes of LMP2199-209, LMP2318-322 and LMP2381-391 from EBV LMP2 had been predicted using bioinformaties methods. The gene fragments of three epitopes were cloned respectively into pET32a(+) vector and transformed into E. coli strain BL21 (DE3). After identification by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting, the expression products were purified by Ni-NTA agarose affinity chromatography. BALB/c mice in immunized groups were immunized by multi-point intracutaneous injection with the three purified epitope proteins,respectively; and mice in control groups were injected with pET32a (+) protein or phosphate buffered saline(PBS), respectively. The sera from mice at week O, week 3 and week 6 of injection were collected for determination of epitope-specific antibody IgG by enzyme linked immunosorbent assay (ELISA) using epitope proteins as coating antigens. The ability of serum antibody recognizing nature EBV antigen was determined at week 6 of immunization. Results Three epitope proteins of LMP2199-209 ,LMP2318-322 and LMP2381-391 were successfully expressed in prokaryotic system. Epitopespecific antibodies IgG could be detected respectively in the sera of all immunized mice, and the levels of antibodies increased with immunized time increasing. The antibody levels in LMP2318-322 immunized group at week 3 and week 6 were significantly higher than that of pET32a (+) protein control group (F= 493.85 and 773.99, respectively; both P＜0. 05), and the antibody levels in LMP2381-391 immunized group at week 3 and week 6 were also significantly higher than that of pET32a (+) protein control group (F= 926.33 and 309.14, respectively; both P＜0.05). Antibody level in LMP2199-209 immunized group at week 6 was significantly higher than that of pET32a ( + ) protein control group (F=87.27, P＜0.05). The antibody IgG in serum from immunized mice with three epitope proteins could all recognize nature EBV antigens, especially LMP2199-209 and LMP2381-391 immunized groups.Conclusions Three possible dominant epitopes of LMP2199-209, LMP2318-322 and LMP2381-391 from EBV LMP2 are prepared by prokaryotic expression system and exhibit obvious immunogenicity, which could be used for further research of EBV infection and related tumor vaccine.

OBJECTIVE: To screen the anti-tumor fraction of ethanol extracts from Thymus quinquecostatus Celak and investigate its anti-tumor effect on human leukemia cell line. METHODS: Ethyl acetate, n-butanol and acetone fractions were separated from the ethanol extracts of wild Thymus quinquecostatus Celak. Growth inhibiting effects of these extracts on human leukemia cell lines K562 and HL-60 were determined by live cell counting and cell growth curve analysis. The possible anti-tumor mechanism was studied by morphological analysis with norcantharidin as a positive control. RESULTS: Ethyl acetate fraction could significantly inhibit the proliferations of K562 and HL-60 cells, and the inhibiting effect depended on the concentration of ethyl acetate fraction. Ethyl acetate fraction could induce apoptosis of K562 and HL-60 cells. The n-butanol and acetone fractions had no significant inhibiting effect on K562 and HL-60 cells. CONCLUSION: Ethyl acetate fraction is the major anti-tumor fraction in ethanol extracts from Thymus quinquecostatus Celak.

Aim To investigate the protective effect of catechin on cerebral ischemia-reperfusion injury in rats and its mechanism.Methods 40 rats were randomly divided into 5 groups:sham operation group,model group and 50,100 and 200 mg·kg~(-1) catechin groups,with 8 rats in each group.The model of focal cerebral ischemia-reperfusion in rats was established with modified sutured-occluded method.The rats in catechin groups were injected with catechin at the matched concentration.The rats in sham operation group and model group were injected with saline.And all rats were given more time in 2 hours after ischemia.Rats were sacrificed for histologic examination after the behavioral test,and their brains were taken to assay the activities of MPO and NOS.Results Catechin at different dosages(50,100 and 200 mg·kg~(-1))could obviously decrease neurological deficit score,repair histological injury,and reduce the activities of MPO and NOS in rats of focal cerebral ischemia-reperfusion injury.Conclusions Catechin can relieve the cerebral ischemia reperfusion injury,and its mechanism may be partly related to the effects of its antiinflammation and antioxidation.

Objective To explore the HLA-A2 restriction and immunogenicity of 5 previously identified HCV-speeific CTL epitopes. Methods Based on T2 cell, to explore the HLA-A2 restriction of previously identified HCV-specific CTL epitopes by MHC-peptide complex stabilization assay;To detect pep-tide-specific CTL in HLA-A2~+ PBMC stimulated by HLA-A2-restricted peptides by intracellular cytokine staining(ICS) and ELISPOT; To explore the cytotoxicity of peptide-specific CTL to same peptide-loaded T2 cells (target cells) by CTL cytotoxicity test. Results Among 5 previously identified CTL epitopes NS4b_78 (SMMAFSAAL) and NS5a_367 (TVSSALAEL) have high-affinity for HLA-A2 molecules(FI 1) ;ELISPOT results shown that NS4b_78(SMMAFSAAL) and NSSa_367(TVSSALAEL) induced high levels of IFN-γ-se-creting cells [(60±6) SFC/10~4 PBMC vs (4±1 ) SFC/10~4 PBMC, P < 0.01 ; (10 ± 3 ) SFC/10~4 PBMC vs (2±1 ) SFC/10~4 PBMC, P <0.01, respectively] ;ICS results indicated that there were high percentages of CD8~+ IFN-γ~+ T cells in total CD8~+T cells stimulated by these peptides [(2.33 ±0.22 ) % vs (0.05±0.01)%, P <0.001 ; (0.36±0.06)% vs (0.03±0.01)%, P <0.001, respectively]. Furthermore,peptide-specific CTL could effectively kill same peptide-loadcd T2 cells. Conclusion NS4b_78 (SMMAF-SAAL) and NSSa_367 (TVSSALAEL) were identified as HLA-A2-restricted CTL epitopes which could in-duce immune response in vitro.

Objective To express in prokaryotic system and to analyze the antigenic specificity of EB virus(EBV) latent membrane protein 2(LMP2) multi-epitopes gene rich of T cell and B cell epitopes.Methods Using on-line prediction service, T cell epitopes and B cell epitopes of EB virus latent membrane protein 2 were predicted. The genes rich of CTL and th cell epitopes were selected as the candidate gene sequences, while B cell epitopes around them were taken into account. The finial selected multi-epitope gene was synthesized after being optimized according to prokaryotic codon bias and inserted into prokaryotic expression vector pET32a( + ) to get the recombinant plasmid: pET32a( + )/EBV-LMP2 multi-epitopes. After transformed into E. coli BL21 (DE3) and induced by IPTG, the target multi-epitopes gene can be expressed as Trx-His fusion protein. The expression products can be identified by SDS-PAGE and Western blot. Moreover, rabbit serum antibody to EBV membrane protein and nasopharyngeal carcinoma(NPC) patient serum were used respectively to detect the antigenic specificity of the multi-epitopes. Meanwhile, 6-8 weeks female BALB/c mice were immunized with EBV-LMP2 multi-epitope at 2 week intervals, three times in all, Trx-His protein and PBS were set as the control groups. At the second week after the last immunization, the mice were sacrificed. LDH and indirect ELISA were taken to detect the specific spleen CTL activityand specific IgG in serum, which reflected the immunogenicity of the EBV-LMP2 multi-epitope. Results Two amino acid sequences which locate at the LMP2 (aa195 -232 ) and LMP2 (aa419-436 ) were selected and connected in series to be the target gene. The recombinant plasmid containing EBV-LMP2 multi-epitope gene successfully constructed and the target protein was expressed in E. coli BL21 ( DE3 ). The relative molecular mass(Mr) of The expression products is about 27 × 103 , which matches up to the expected Mr. The antigenic specificity of the multi-epitopes protein was identified by Western blot and the multi-epitopes protein also can be detected by rabbit serum antibody to EBV membrane protein and NPC patient serum respectively. In the result of the animal experiment, EBV-LMP2 multi-epitope was able to induce the specific CTL activity in BALB/c mice. With the increasing of the effector: target ( E: T) 1: 5,1: 10, 1: 25, the CTL activity was also increased wih( 12.52% + 2.59% ), (21.80% + 1.08% ), (23.68% + 3.74% ) respectively; EBV-LMP2 multi-epitope was able to induce LMP2-specific antibody response(A490 =0.258 +0.040) as compared with Trx-His protein(A490 =0.095 +0.011) and PBS(A490 =0.068 +0.014,P＜0.05＝. Conclusion The EBV-LMP2 multi-epitopes gene was designed successfully and expressed precisely in prokaryotic expression system with good antigenicity and immunogenicity.

Objective To investigate the cross reaction characteristics of recombinant human papillomavirus 16 type L2 full-length fusion protein in HPV types of 6, 11, 18.Methods The serum samples of 108 condyloma acuminatum patients, 156 cervix cancer patients and 100 healthy control subjects were collected.The gene of full-length HPV16 L2 was amplificated from the tissue DNA of cervical cancer patient and inserted into the prokaryotic expression vector PGEX-4T-1 to construct the recombinant plasmid PGEX-4T-1-HPV16 L2.After sequencing identification, the recombinant plasmid was tranformed into E.coli BL21 (DE3).After induction by IPTG, the fusion protein containing HPV16 L2 was expressed and analyzed by both SDS-PAGE and WB.Furthermore, the specific binding capacity of the fusion protein to the HPV 6,11, 16 and 18 DNA positive patient's sera were analyzed by WB.The fusion protein was purified with NiNTA Agarose Kit and coated with ELISA reaction plates.The specific serum IgG were detected by indirect ELISA.Results The recombinant plasmid PGEX-4T-1-HPV16 L2 was constructed successfully. Highly expressed HPV16 L2 full-length fusion protein was obtained and the expression level was 27.2 %.The relative molecular mass(Mr) of the fusion protein is about 82 × 103, which matches up to the expected Mr.Meanwhile, the sera of HPV 6,11,16,18 DNA positive patients were used as the primary antibody and the Mr of the specific band was detected to be about 82 × 103 by WB.The results of indirect ELISA showed that the average levels of specific IgG in condyloma acuminatum group, cervical cancer group and healthy control subjects were 0.848 ±0.257, 0.822 ±0.247 and 0.173 ±0.143 with the positive rate of 92.6%, 94.2%and 8.0% respectively.There was no significance of the specific IgG levels between condyloma acuminatum group and cervical cancer group ( F = 0, P ＞ 0.05 ), but there was significant difference of specific IgG levels and positivity among the three groups ( F = 305.201 ,x2 = 253.178, P ＜ 0.01 ).Conclusions The HPV16 L2 full-length fusion protein has better antigenicity.However cross reactions with HPV6, 11 and 18 were found.It can be applied in serological screening reagents for HPV infection and associated cancer.

Objective To study on the specific cellular immune response produced in BALB/c mice immunized with human papillomavirus (HPV) type 6b capsid protein L1 and Chlamydia trachomatis (Ct) major outer membrane protein(MOMP) multi-epitope chimeric DNA (HPV6b L1/Ct MOMP multiepitope) , and the enhancement of the specific cellular immune response to Ct MOMP multi-epitope by HPV6b L1. Methods The Ct MOMP multi-epitope gene was connected to the C terminal of HPV6b L1,the gene of HPV6b L1 had been optimized according to the codon usage of eukaryotic system, and then the HPV6b L1/Ct MOMP multi-epitope chimeric gene was cloned to pcDNA3.1 ( + ) vector. After identification by restriction enzyme digestion and DNA sequencing, the recombinant plasmid was transfected into COS-7 cells, Indirect Immunofluorescence (IIF) was used to confirm the expression of proteins. Then, BALB/c mice were randomly assigned to receive (intramuscular injection) either pcDNA3.1 ( + )/HPV6b L1/Ct MOMP or pcDNA3.1 ( + )/Ct MOMP or pcDNA3.1 ( + ) or PBS ( n = 12, 150 μg/time), and the same immunization schedule was repeated third times at 2 week intervals. The level of cytokine( IFN-γ, IL-4, IL-10) -producing CD3+ T cells in spleen, the cytotoxicity of Ct MOMP-specific and HPV6b L1-specific cytotoxic T lymphocyte (CTL) in spleen were detected by intracellular cytokine staining-fluorescence activated cell sorter (ICS-FACS) and LDH release assays, respectively. Results After immunization, when the efCTL (44.56%±4.02%, 35.35% ±2.89% ) and HPV6b L1 specific cytotoxicity of CTL (27.08% ±2.04%, 21.68% ±4.06% ) in pcDNA3.1 ( + )/HPV6b L1/Ct MOMP multi-epitope chimeric DNA immunized mice, were significantly higher than that in pcDNA3.1 ( + )/Ct MOMP multi-epitope DNA (35.50%±2.68%, 30.24% ±1.75%; 12.27% ±3.36%, 9.32% ±3.07%) and other control groups(F=72.87, F=114.55, P＜0.05; F=30.04, F=10.47, P＜0.05), and Ct MOMP multi-epitope specific cytotoxicity of CTL in pcDNA3.1 ( + )/Ct MOMP multi-epitope DNA immunized mice were significantly higher than that in control groups( F = 58.85, F = 120.21; P<0.05). The level of intracellular cytokine IFN-γ in pcDNA3.1 ( + )/HPV6b L1/Ct MOMP multi-epitope DNA immunized mice(4.34% ±0.06%)was higher significantly than that in pcDNA3.1 ( + )/Ct MOMP multi-epitope DNA immunized mice(3.14% ± 0.18%, P<0.05 ) and other control groups ( F = 473.83, P<0.05 ), while, the levels of IL-4 ( F =0.97, P ＞ 0.05 ) and IL-10 ( F = 2.25, P ＞ 0.05 ) had no significant difference between groups. Conclusion Both Ct MOMP and HPV6b L1 protein specific cellular immune response could be induced in BALB/c mice immunized with HPV6b L1/Ct MOMP multi-epitope chimeric plasmid, and the HPV6b L1 gene optimized by eukaryotic codon could significantly enhance the cellular immune response induced by Ct MOMP multi-epitope gene in BALB/c mice.