Objective To clone the mature peptide gene of seo, construct two kinds of prokaryotic fusion expression vector, obtain recombinant staphylococcal enterotoxin O(SEO) and evaluate its biological activity. Methods The seo gene was amplified from ZNZ2-3 strain of Staphylococcus xylosus by designed primers and it was cloned into fusion vector pGEX-6P-1 and pET28a. The soluble recombinant protein(GST-SEO) was expressed in E. coli BL21 host cells, the purified GST-SEO was obtained by a single step of affini-ty chromatography using Glutathinione Sepharose 4B colume. Another fusion protein(P28-SEO) with his-tag was expressed in E. coli BL21 ( DE3), the purified P28-SEO protein was harvested by nickel chelate affinity chromatography method. The antigenicity of recombinant SEO was tested by Western blot. The stimulating effects of recombinant SEO on mouse lymphocytes was tested by MTT. The activity of Caspase 3 and the ap-optosis of DNA ladder were tested. Results The nucleotide sequence of the cloned seo gene was the same as that of reported in GenBank. The soluble recombinant protein GST-SEO was expressed at 25% expression level, and P28-SEO was 22%. The Western blot by GST-SEO-positive sera demonstrated that the recombi-nant SEO had good immunogenicity. The MTY assay of the enterotoxin activity showed that low dose of re-combinant SEO stimulated the proliferation of mice spleen lymphocytes, higher doses will lead to apoptosis. Conclusion Two of the recombinant SEO still have superantigen activity, and can lead to apoptosis of mice splenocytes.

Objective:To investigate the clinical and biological characteristics of relapsed childhood low-risk acute B lymphoblastic leukemia (B-ALL).Methods:The clinical and laboratory data of 34 children who admitted in Beijing Boren Hospital from July 2017 to July 2018 were retrospectively analyzed, and 127-339 mutations of hematological malignancy related genes were analyzed.Results:The median time from the diagnosis to the recurrence was 871 d (87-1 446 d). The recurrence at early stage and late stage had 26 cases (76%) and 8 cases (24%), respectively. The recurrence before maintenance treatment, during maintenance therapy and after withdrawal of chemotherapy had 3 cases (9%), 12 cases (35%) and 19 cases (56%) (13 cases relapsed within 1 year after withdrawal, 6 cases relapsed after withdrawal 1-2 years and no one relapsed after withdrawal 2 years). The sites of recurrence included bone marrow alone accounting for 26 cases (76%), both intramedullary and extramedullary disease (EMD) accounting for 6 cases (18%), EMD alone accounting for 2 cases (6%). Flow cytometry showed that 9 patients presented minimal residual disease (MRD)-positive (6 cases with one positive, 2 cases with twice positive and 1 case with 3 times positive), including 8 cases occurred at early stage and 1 case occurred at late stage; and the level of MRD was 0.02%-3.82%. Complex chromosomal karyotype appeared in 6 relapsed children with normal or hyperdiploid karyotype at first diagnosis. Hematological malignancy related gene mutation detection was made in 28 cases, and the results showed that each patient had at least one gene mutation, and 2 or more gene mutations were detected in 25 cases (89%). The high frequency of gene mutations were as follows: CREBBP (7 cases, 25%), NRAS (7 cases, 25%), KRAS(7 cases, 25%), TP53 (4 cases, 14%), and NT5C2 (4 cases, 14%).Conclusions:The recurrence of childhood low-risk B-ALL occurs mostly in the maintenance treatment or in two years of withdrawal of chemotherapy. Positive MRD after complete remission is likely to show the risk of early recurrence. The gene mutations after the poor prognosis in cancer cells may be related to the recurrence of childhood low-risk B-ALL, and the common gene mutations include CREBBP, RAS signaling pathways genes and TP53, NT5C2.

Objective:To explore the mechanism of mTOR/HIF-1α signaling pathway in Budd-Chiari syndrome (B-CS) liver fibrosis.Methods:Twenty male C57 mice were randomly divided into Sham operation group (Sham), sham operation+ rapamycin (Sham+ Ra) group, B-CS group, B-CS+ rapamycin (B-CS+ Ra) Group, 5 in each group. The B-CS mouse model was constructed by partial ligation of the inferior vena cava(IVC) at the posterior segment of the liver; IVC was not ligated in the Sham group. Mice in Sham+ Ra and B-CS+ Ra groups were intraperitoneally injected with rapamycin (2 mg/kg, 5% DMSO solution preparation) every other day, Sham group and B-CS group were injected with the same dose of 5% DMSO solution.After 6 weeks, samples were taken, and part of the liver tissue was used to make paraffin sections for hematoxylin-eosin (HE) and Sirus Red staining to observe the pathological changes, and immunohistochemical staining to detect the expression of α-SMA and Fibrinogen in liver tissues; Protein and RNA were extracted from fresh liver tissue, and Western-blot was used to detect α-SMA, Fibrinogen, p-mTOR, mTOR, HIF-1α, Collagen I, and VEGF protein levels. Real-time fluorescent quantitative PCR was used to detect mTOR, HIF-1α, CollagenⅠ, VEGF mRNA levels.Measurement data were expressed as mean±standard deviation ( ± s), and the comparison between groups was performed by one-way ANOVA test. Results:The results of pathological staining showed that in the B-CS group, there was severe congestion around the central vein of the liver and sinusoids, widening of the sinus space, and increased collagen deposition, indicating that this study successfully established a mouse B-CS liver fibrosis model. The expression levels of fibrosis indicators α-SMA and Collagen I protein, mTOR pathway related indicators p-mTOR and HIF-1α protein, and microthrombus indicator Fibrinogen protein in the Sham group were 0.027±0.012, 0.337±0.008, 0.138±0.024, 0.296±0.113, 0.733±0.192; B-CS group were 0.986±0.001, 0.927±0.055, 0.936±0.044, 1.693±0.443, 1.612±0.068, and the differences were statistically significant ( P<0.05). The expression levels of B-CS+ Ra group were 0.707±0.078, 0.311±0.024, 0.332±0.094, 0.254±0.117, 0.569±0.075, which were statistically significant compared with B-CS group ( P<0.05). Conclusions:The mTOR/HIF-1α signaling pathway is significantly activated in mouse B-CS liver fibrosis. This pathway may participate in the development of liver fibrosis by regulating microthrombosis.