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Biomedical subjects

Jun Cheng

Publications and source records attributed to Jun Cheng.

134 records · Page 8Linked to original sources
PubMed2002

[Quasispecies and variations of hepatitis B virus: core promotor region as an example].

OBJECTIVE: To investigate the HBV quasispecies groups in the patients with chronic HBV infection. METHODS: A set of specific primers was synthesized according to DNA sequence of HBV strain found in China. The whole core promoter (CP) region was amplified by PCR method from the sera of 3 patients with chronic HBV infection, and the PCR products were subcloned into pGEM Teasy vectors. The clones were randomly selected to be sequenced. Sequence comparison of the selected clones was made to find the difference. RESULTS: By comparison, it was found that each sequence of selected clones was different. The point mutation always occurred in TATA-like boxes, especially from T to C replacement on 184 site. There is a hot region (33.3% 5/15) in basic core promoter where deletion mutation frequently happened. CONCLUSIONS: There is a hot deletion region near DR I in CP. The replacement at 184 nt (T to C) in the third TATA-like box may influence the expression of pre-C/C protein. The sequencing results suggest that there are HBV quasispecies groups in chronically infected patients.

DNA, Viral↗
PubMed2002

[Studies on the phenylpropanoids from Eucommia ulmoides].

OBJECTIVE: To study the chemical constituents from the leaves of Eucommia ulmoides. METHOD: The constituents were isolated by chromatography method and the structures were identified on the basis of spectral analysis. RESULT: Six compounds, ursolic acid(1), beta-sitosterol(2), p-coumaric(3), caffeic acid ethyl ester(4), chlorogenic acid(5) and syringin(6) were obtained. CONCLUSION: Compound 3, 4, 5 were obtained from the plant for the first time.

Caffeic Acids↗
PubMed2002

Cloning and analysis of the genomic DNA sequence of augmenter of liver regeneration from rat.

OBJECTIVE: To search for genomic DNA sequence of the augmenter of liver regeneration (ALR) of rat. METHODS: Polymerase chain reaction (PCR) with specific primers was used to amplify the sequence from the rat genome. RESULTS: A piece of genomic DNA sequence and a piece of pseudogene of rat ALR were identified. The lengths of the gene and pseudogene are 1508 bp and 442 bp, respectively. The ALR gene of rat includes 3 exons and 2 introns. The 442 bp DNA sequence may represent a pseudogene or a ALR-related peptide. Predicted amino acid sequence analysis showed that there were 14 different amino acid residues between the gene and pseudogene. ALR-related peptide is 84 amino acid residues in length and relates closely to ALR protein. CONCLUSION: There might be a multigene family of ALR in rat.

Amino Acid Sequence↗
PubMed2002

Cloning and expression of the gene of augmenter of liver regeneration in yeast cells.

OBJECTIVE: To study the function of augmenter of liver regeneration (ALR) as a regulatory factor that specifically stimulates hepatic cell regeneration, we constructed yeast expressive vector of ALR and expressed it in yeast cells. METHODS: Total RNA was extracted from HepG2 cells, and reverse transcription polymerase chain reaction (RT-PCR) was performed to amplify the coding region of ALR. The products were cloned into PGEM-T vector and sequenced, then cloned into PGBK T7 vector. The recombinant plasmid PGBK T7-ALR was transformed into yeast AH109. The yeast protein was extracted and analyzed by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting hybridization technique. RESULTS: DNA sequencing results confirmed that the coding region of ALR was correctly inserted into the yeast expression vector, and Western blotting assay showed that recombinant ALR was successfully expressed in yeast. Its molecular weight was identical to the theoretical value of 15 000 Da; the protein was found inside the yeast cells. CONCLUSION: The successful expression of ALR in yeast cells makes it possible to study further on its biological function.

Blotting, Western↗
PubMed2002

Quasispecies groups in the core promoter region of hepatitis B virus.

OBJECTIVES: To investigate the mutation of the basic core promoter (BCP) of hepatitis B virus (HBV) and clarify the significance of HBV quasispecies groups in patients with chronic HBV infection. METHODS: A set of specific primers was synthesized according to the HBV DNA sequence of a Chinese strain. The BCP was amplified by PCR method from the serum of 40 patients with chronic HBV infection, and the PCR products of 2 patients were subcloned into pGEM Teasy vectors. Polyacrylamide gel electrophoresis (PAGE) was employed to display the deletion mutations, and clones with differential length were selected to be sequenced. Sequence comparison was made to find the difference. RESULTS: Two or three bands were displayed by PAGE in 60% patients. The results of sequence analysis showed that there are some kinds of mutations in the BCP region. The substitution always occurs in TATA-like boxes, especially from T to C on 140 site. The deletion mutations were detected in TA1, TA2 and TA3. The 8bp, 20bp deletion mutations frequently happened. CONCLUSIONS: There is a hot deletion region in the BCP. The deletion and the substitution in the TATA-like box may influence the expression of preC/C protein. The sequencing results indicate that there are HBV quasispecies groups in patients with chronic HBV infection.

Base Sequence↗
PubMed2002

Cloning and expression of the preS1 gene of hepatitis B virus in yeast cells.

OBJECTIVE: To investigate the complex functions of HBV preS1 protein, we constructed HBV preS1 gene expression vector and expressed it in yeast cells. METHODS: Polymerase chain reaction (PCR) was performed to amplify the gene of HBV preS1 from the plasmid pCP10 containing the whole DNA fragment of HBV ayw subtype as template and the PCR product was cloned into the pGEM-T vector for sequencing. After being identified, the HBV preS1 gene was cut from the pGEM-T vector by EcoR I and Pst I restriction enzymes, and cloned into yeast expressive plasmid pGBKT7 to construct pGBKT7-preS1 recombinant expressive plasmid. This plasmid was transformed into yeast cell AH109 and expressed in it. The yeast protein was isolated and analyzed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE) and Western blotting. RESULTS: The HBV preS1 gene was amplified successfully and identified by DNA sequencing. The PCR products were coincided completely with the reported sequence. The digested fragments were cloned into the pGBKT7 vector and transformed into yeast cell AH109. The results of SDS-PAGE and Western blotting assay showed: (1) The HBV preS1 protein was expressed and existed in yeast cells; (2) The molecular weight of the expression product was about 30 000 D. CONCLUSION: The HBV preS1 gene was successfully cloned and expressed in yeast cells.

Blotting, Western↗
PubMedDate not supplied

Epstein-Barr virus infected lymphoepithelial carcinomas of the salivary gland in the Russia-Asia area: a clinicopathologic study of 160 cases.

In order to determine the prevalence of the Epstein-Barr virus (EBV) infection in salivary gland lymphoepithelial carcinomas (LEC), we have collected 160 cases from Asian countries and Russia. All the cases examined by PCR for EBV DNA BamHI fragment and in-situ hybridization for EBER-1, EBV encoded small RNA, showed positivity for EBV infection in LEC cells, while no positive signals were found in any other salivary neoplasm examined. The incidence of LEC was highest in Guanzhou, followed by Shanghai and Chengdu and lowest in the northern parts of China, Seoul, Niigata, and Moscow. The mean age of the patients with LEC was 43.9 years with no sex predilection. The Chinese patients were of the Han race, only including minor races. There were ninety-five cases found with LEC in the parotid gland (75%), 20 in the submandibular gland (5%), and 28 in the minor salivary gland (20%). Histologically, the LECs were classified into two types: small nest type and large nest type. The latter type consisted of large-sized tumor cell nests and dense lymphocytic stromata and more frequently occurred in the minor salivary gland. The former consisted of small-sized tumor cell nests with fibrous and lymphocyte-depleted stromata, which were more frequently found in the parotid gland. The results indicated that EBV infection and certain geographic factors play important roles in the pathogenesis of the salivary LEC.

Carcinoma, Squamous Cell↗