Biomedical subjects

Li-Xin Zhu

Publications and source records attributed to Li-Xin Zhu.

7 recordsLinked to original sources

PubMed2002

Ultrastructural study of the vascular endothelium of patients with spontaneous rupture of hepatocellular carcinoma.

BACKGROUND: Spontaneous rupture of hepatocellular carcinoma (HCC) is common in Asia and Africa, although the mechanism is unclear. In our previous study, we found that vascular injury exemplified by collagenase synthesis and collagen degradation in small arteries was related to the HCC rupture. METHODS: In this study, transmission electron microscopy was used to study 22 specimens from ruptured HCC and non-ruptured HCC. RESULTS: In nine specimens of ruptured HCC, there was evidence of vascular injury with fewer cell junctions and larger fenestrae in vascular endothelial cells. The phenomenon of increased endothelial protein synthesis was also present. In the specimens of non-ruptured HCC, evidence of vascular injury was found in only two cases (p < 0.01). Fewer cell junctions and larger fenestrae could increase the permeability of the vascular wall. Increased protein synthesis in endothelial cells correlates with the phenomenon that more collagenase is expressed in these cells. The resulting breakdown of collagen could render the blood vessels weak; hence, these blood vessels are more prone to splitting/breakage. CONCLUSION: We conclude from our study that this vascular injury may result in HCC rupture.

Adult↗

PubMed2002

Full-length core sequence dependent complex-type glycosylation of hepatitis C virus E2 glycoprotein.

AIM: To study HCV polyprotein processing is important for the understanding of the natural history of HCV and the design of vaccines against HCV. The purpose of this study is to investigate the affection of context sequences on hepatitis C virus (HCV) E2 processing. METHODS: HCV genes of different lengths were expressed and compared in vaccinia virus/T7 system with homologous patient serum S94 and mouse anti-serum M( E2116) raised against E.coli -derived E2 peptide, respectively. Deglycosylation analysis and GNA ( Galanthus nivalus ) lectin binding assay were performed to study the post-translational processing of the expressed products. RESULTS: E2 glycoproteins with different molecular weights (-75 kDa and -60 kDa) were detected using S94 and M( E2116), respectively. Deglycosylation analysis showed that this difference was mainly due to different glycosylation. Endo H resistance and its failure to bind to GNA lectin demonstrated that the higher molecular weight form (75 kDa) of E2 was complex-type glycosylated, which was readily recognized by homologous patient serum S94. Expression of complex-type glycosylated E2 could not be detected in all of the core-truncated constructs tested, but readily detected in constructs encoding full-length core sequences. CONCLUSION: The upstream conserved full-length core coding sequence was required for the production of E2 glycoproteins carrying complex-type N-glycans which reacted strongly with homologous patient serum and therefore possibly represented more mature forms of E2. As complex-type N-glycans indicated modification by Golgi enzymes, the results suggest that the presence of full-length core might be critical for E1/E2 complex to leave ER. Our data may contribute to a better understanding of the processing of HCV structural proteins as well as HCV morphogenesis.

Animals↗

PubMed2002

Expression and characterization of hepatitis C Virus E2 glycoprotein fused to hepatitis B virus preS1(21-47) fragment in CHO cells.

To stably express hepatitis C virus (HCV) E2 glycoprotein in CHO cells and facilitate the detection and purification of the expression products, the gene fragment encoding N-terminal 277 amino acids of this protein was fused to the fragment encoding hepatitis B virus (HBV) preS1(21-47) region and inserted into a secretion vector pSecTagB. CHO cells transfected with the recombinant plasmid carrying fusion gene were selected under growth pressure of Zeocin. Secreted fusion products and its cell-associated counterpart were detected by Western blot using E2 specific or preS1 specific antibodies. Glycans carried by the expression products were analyzed with glycan-type specific glycosidases. Most of the cell-associated E2 were found to be high-mannose-type glycosylated, while the secreted E2 proteins were found to be mostly complex-type glycosylated, suggesting further modification in Golgi apparatus upon secretion. Primary studies showed that the fusion antigen could be specifically bind to and elute from anti-preS1 antibody coupled Sepharose resin, suggesting that large-scale preparation of the fusion antigen is feasible with an immunoaffinity resin. This work will contribute to the further study of immunological properties of HCV E2 glycoprotein and also to the study of recombinant HBV/HCV vaccine.

Animals↗

PubMed2002

DNA immunization with recombinant HCV E2 expression plasmids.

DNA-based immunization, the delivery of plasmid DNA by direct inoculation, is a newly developed method of vaccination. Besides of many advantages, DNA immunization was demonstrated to generate weaker antibody and CTL responses than did protein and live attenuated vaccines, respectively. To circumvent this shortage, several methods were tested such as using different vector, changing injection mode, and co-expressing cytokines, etc. The studies showed that many factors could greatly affect the immune responses to DNA vaccine. The aim of this study is to compare different vectors for the presentation of the HCV E2 to generate immune responses by using DNA-based immunization. Four expression plasmids, with different promoter types and with or without signal sequences were constructed, which encode C-terminally truncated E2 (384-660) with HBV preS1 21-47 tag fused to its N-termini. Transient expression in HeLa cells showed that only recombinant plasmids with signal sequence could be expressed and properly processed, and the product could be secreted into medium. Protein expression level is slightly higher in plasmids with CMV promoter than with EF1alpha promoter. After immunization of C57BL/6 mice, all the recombinant constructs could elicit both anti-preS1 and anti-E2 antibodies. But only pCMV Sec-S1E2t660 with both CMV promoter and signal sequence could induce high-level and long-lasting antibody, showing that it is a good vaccine candidate. Possible reasons for the different immune responses to these constructs were discussed.

Animals↗

PubMed2002

Cartilage end-plate rupture of the lumbar vertebrae: report of 7 cases.

The authors report the clinical manifestations, imaging features, surgical approaches and the outcome of 7 cases of cartilage end-plate rupture of the lumber vertebrae, attempting to explore the pathogenesis and describe the clinical and pathological features of the disease. The diagnosis and treatment are also discussed in brief.

Adult↗

PubMed2001

High Frequency of Homologous Recombination in the Genome of Modified Vaccinia Virus Ankara Strain (MVA).

MVA is a genetically modified vaccinia virus strain, which is replication defective and extremely safe for research and clinical use. To further improve the safety of MVA and achieve more efficient selection of recombinant constructs, a transient selection marker system has been developed, which contains vaccinia virus k1l gene flanked by two identical fragments. In this report, four recombinant MVAs were constructed with this system, and homologous recombination of recombinant MVAs was studied during the construction procedure. The results showed that the recombination frequency of these rMVAs was significantly high, though lower than that observed in other vaccinia virus strains. The k1l free rMVAs could be conveniently obtained after 3 or 4 blind passages. Our data indicated that recombinant MVA with a transient selection marker system was safe for use as live vaccine and gene therapy vector for human. In addition, blind passages could enhance the efficiency in isolation of k1l free recombinants

Journal Article↗

PubMed1999

Fusion Expression, Immunogenicity and Applications of C-terminally Truncated HCV Core Proteins.

Clones expressing full-length(aa 1-191) or C-terminally truncated forms (aa 1-69 and aa 1-40) of hepatitis C virus core(HCc) protein fused to the C-terminal of glutathione S-transferase(GST) were constructed and their expressions in different strains of Escherichia coli were compared. The expressed proteins were soluble. ELISA and Western blot analyses showed that GSTC191 was poorly expressed and had poor stability, whereas GSTC69 and GSTC40 were stable and could be purified to 90% purity in a single step on glutathione-Sepharose 4B. Mice immunized with these purified proteins produced high-titre antibodies. As an application, purified GSTC69 and GSTC40 were used in a preliminary assay of anti-HCc antibodies in patients'sera, and results showed that they had high specificity in the assay.

Journal Article↗