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Biomedical subjects

Jun Cheng

Publications and source records attributed to Jun Cheng.

At least 109 records · Page 6Linked to original sources
PubMed2003

Ectopic expression of kruppel like factor 4 (Klf4) accelerates formation of the epidermal permeability barrier.

Dysfunction of the epidermal permeability barrier can result in dehydration, electrolyte imbalance and poor thermoregulation. Immature skin is a portal of entry for infectious agents and potential toxins in topically applied substances. As the skin is one of the last organs to mature in utero, premature infants born before 34 weeks gestation are at great risk for complications. The transcription factor kruppel-like factor 4 (Klf4), has been shown by a targeted ablation, to have an essential function in barrier acquisition. We investigated whether Klf4 expression in utero is sufficient to establish the epidermal barrier. Specifically, we generated lines of mice that express Klf4 from a tetracycline inducible promoter when crossed with transgenic mice expressing the tetracycline transactivator tTA from the epidermal keratin 5 promoter. These mice exhibit acceleration in barrier acquisition as manifest by the exclusion of a dye solution one day earlier in development than controls. Underlying this dye impermeability are morphological changes, including an increased number of stratified layers, expression of terminal differentiation markers and assembly of cornified envelopes. By all criteria, Klf4 ectopic expression accelerates the normal process of terminal differentiation. Premature barrier acquisition in these mice follows the normal pattern rather than the pattern of the transgene promoter, indicating that there are fields of competence in which KLF4 acts. Although other transgenic mice have perturbed barrier acquisition, these mice are the first to accelerate the process of barrier establishment. These studies show that KLF4 regulates barrier acquisition and provides an animal model for studying how to accelerate the process of barrier acquisition for the premature infant.

Animals↗
PubMed2003

Interaction between hepatitis C virus core protein and translin protein--a possible molecular mechanism for hepatocellular carcinoma and lymphoma caused by hepatitis C virus.

AIM: To investigate the interaction between hepatitis C virus core protein and translin protein and its role in the pathogenensis of hepatocellular carcinoma and lymphoma. METHODS: With the components of the yeast two hybrid system 3, "bait" plasmids of HCV core the gene was constructed. After proving that hepatitis C virus core protein could be firmly expressed in AH109 yeast strains, yeast two- hybrid screening was performed by mating AH109 with Y187 that transformed with liver cDNA library plasmids-pACT2 and then plated on quadruple dropout (QDO) medium and then assayed for alpha-gal activity. Sequencing analysis of the genes of library plasmids in yeast colonies that could grow on QDO with alpha-gal activity was performed. The interaction between HCV core protein and the protein we obtained from positive colony was further confirmed by repeating yeast two - hybrid analysis and coimmunoprecipitation in vitro. RESULTS: A gene from a positive colony was the gene of translin, a recombination hotspot binding protein. The interaction between HCV core protein and translin protein could be proved not only in yeast, but also in vitro. CONCLUSION: The core protein of HCV can interact with translin protein. This can partly explain the molecular mechanism for hepatocellular carcinoma and lymphoma caused by HCV.

Carcinoma, Hepatocellular↗
PubMed2003

[Cloning of genes transactivated by hepatitis B virus X protein].

OBJECTIVE: To construct a subtractive cDNA library of genes transactivated by hepatitis B virus X protein (HBX) using suppression subtractive hybridization (SSH) technique and to clone genes associated with HBX transactivating function. METHODS: The mRNA was isolated from HepG2 cells transfected with pcDNA3.1(-)-X and pcDNA3.1(-) empty vector respectively, then cDNA was synthesized. After restriction enzyme RsaI digestion, a number of small size cDNA was obtained. Then tester cDNA was subdivided into two portions and each was ligated with different cDNA adaptor. After tester cDNA was hybridized with driver cDNA twice and underwent nested polymerase chain reaction (PCR) twice the production was subcloned into T/A plasmid vectors to set up the subtractive cDNA library. Amplification of the library was carried out with E. coli strain JM109, some cDNA was sequenced and analyzed in GenBank with Blast. RESULTS: The subtractive cDNA library of genes transactivated by HBX was constructed. The amplified library contained 85 positive clones, and colony PCR showed that these clones contained 200-1000 bp inserts. 65 clones were analyzed by sequencing and bioinformatics, which suggested nineteen known genes and fifteen genes with unknown function. CONCLUSION: A subtractive cDNA library of genes transactivated by HBX using SSH technique has been constructed successfully, which may bring some new clues for studying the biological functions of HBX and the pathogenesis of hepatoma.

Cloning, Molecular↗
PubMed2003

[Screening of the genes of hepatitis B virus PreS2 interacting proteins].

OBJECTIVE: To screen and clone the genes of proteins in hepatocytes interacting with hepatitis B virus (HBV) PreS2 by yeast-two hybridization technique. METHODS: The HBV PreS2 gene was amplified by polymerase chain reaction (PCR) and HBV PreS2 bait plasmid was constructed by using yeast-two hybridization system 3, then transformed into yeast AH109, followed by mating with yeast Y187 containing liver cDNA library plasmid in 2 YPDA medium. Diploid yeast was plated on synthetic dropout nutrient medium (SD/-Trp-Leu-Ade-His) and synthetic dropout nutrient medium (SD/-Trp-Leu-Ade-His) containing X-alpha-gal for selecting positive blue clones, then amplified by PCR, sequenced, and performed bioinformatics analysis. RESULTS: HBV PreS2 gene was cloned successfully and expressed in yeast AH109.Twenty-six positive colonies were selected, among them, twelve containing metallothionein 2A, one cytochrome C oxidase II, two cytochrome P450 subfamily IV4F, two cytochrome c oxidase subunit 4 isoform 1, three albumin (ALB), one Na(+)K(+) transporting ATPase beta-1 polypeptide, two prealbumin, one lectin galactoside-binding subunit, and Two new genes with unknown function. CONCLUSION: Genes of HBV PreS2 interacting proteins have been successfully cloned, which brings some new clues for studying the biological functions of HBV PreS2 and related proteins.

Cloning, Molecular↗
PubMed2003

[The short-term and long-term treatment outcomes in patients with pulmonary tuberculosis positive for drug-resistant and sensitive strains].

OBJECTIVES: To analyze the treatment outcomes in patients with smear positive tuberculosis, and to compare the difference in treatment response among patients infected with drug-sensitive and drug-resistant strains. METHODS: From 1998 to 2000, seven hundred and seventy-seven patients with primary smear-positive tuberculosis, which were from 30 surveillance sites, were followed for two years to monitor their treatment outcomes. RESULTS: At the completion of the 6 months' therapy, the overall rate of treatment failure was 1.8%, 2.6% for the drug-resistant cases and 1.6% for the drug-sensitive cases. Six-month follow-up showed a positive conversion rate of 2.7% in all the cases, 8.5% and 1.2% (P < 0.005) in the drug-resistant and the drug-sensitive cases respectively. One year follow-up showed that the positive conversion rate was 2.6% in all the cases, 6.9% and 1.6% (P < 0.005) in the drug-resistant and the drug-sensitive cases, respectively. Two-year follow-up showed an overall positive conversion rate of 1.3%, 1.0% and 1.3% in the drug-resistant and the drug-sensitive cases, respectively. Of the 152 drug-resistant cases, the rate of treatment failure was 2.6% at the completion of 6 months' therapy, but in cases with MDR-TB the rate was 10.3%. Six-month follow-up showed an overall positive conversion rate of 8.5%, but the rate reached 37.0% in cases with MDR-TB. One-year and two-year follow-up showed that the positive conversion rates were 6.9% and 1.0% respectively in all the drug-resistant cases, but 6.3% and 6.7% respectively in the MDR cases. CONCLUSIONS: Under the guidelines of the National Tuberculosis Program (NTP), the 2H(3)R(3)S(3)Z(3)/4H(3)R(3) regimen for primary smear-positive pulmonary TB was effective. But the cure rate was lower and the positive conversion rate higher in patients with MDR-TB.

Adolescent↗
PubMed2003

[Synergetic transactivating effect of HCV core and HBV X proteins on SV40 early promoter/enhancer].

BACKGROUND: To investigate the synergetic transactivating effects of HCV core and HBV X proteins. METHODS: HCV core and HBV X protein-expressing plasmids were constructed with the vector pcDNA3.1(-). The plasmids were transfected into HepG2 cells and cotransfected Hep2 cells with reporter plasmid Psv-lacZ by lipofectamine plus reagents. The virus proteins produced in transient expression system were detected at the transcription and translation levels. The activity of b-galactosidase was detected, which reflected the transactivating function of the proteins. RESULTS: The expression of plasmids were detected in soluble protein cell extracts of transiently transfected HepG2 cells. HCV core protein activated the b-galactosidase expression at a value 4.9 times higher than the control, while HBV X protein activated at a value 3.5 times. It arrived at 9 times transfected with the plasmids simultaneously. The activating effect increased in relation to the amount of plasmids. CONCLUSIONS: The results suggested that the two kinds of virus proteins have transactivating effect on SV40 early promoter/enhancer, and they acted synergistically. These contribute to explain the mechanisms of liver injury or tumorigenesis induced by HCV or/and HBV infection.

Animals↗
PubMed2003

[A comparative study of male patient's sexual function before and after kidney transplantation].

OBJECTIVES: To investigate sexual function before and after kidney transplantation in patients with chronic nephrosis. METHODS: Eighty-six male patients were divided into 3 age groups: young-age group (Group A), middle-age group(Group B) and elder-age group(Group C). Sexual function, including potency, frequency and satisfaction of intercourse before and after the sickening, and after transplantation, were recorded in each group. RESULTS: All the patients were potent before suffering from nephrosis. The proportion of patients who were potent after catching the disease in Group A, B and C was 28.6%, 13.8% and 9.1%, respectively. Notably, the proportion of patients remaining potent after transplantation in Group A, B and C was 88.6%, 75.9% and 63.6%, respectively. CONCLUSIONS: Quality of sexual life is significantly improved after kidney transplantation. The younger the patients, the better the improvement.

Adult↗
PubMed2003

Screening of augmenter of liver regeneration-binding proteins by yeast-two hybrid technique.

OBJECTIVE: To investigate the biological function of augmenter of liver regeneration (ALR), we used yeast-two hybrid technique to detect proteins in hepatocytes interacting with ALR. METHODS: ALR bait plasmid was constructed by using yeast-two hybrid system 3, then transformed into yeast AH109. The transformed yeast was mated with yeast Y187 containing liver cDNA library plasmid in a 2XYPDA medium. Diploid yeast was plated on a synthetic dropout nutrient medium (SD/-Trp-Leu-His-Ade) containing x-alpha-gal for selection and screening. After extracting and sequencing of the plasmid from blue colonies. Analysis was performed by bioinformatics. RESULTS: Of 36 colonies sequenced, 14 are metallothionein, 12 albumin, and 3 selenoprotein P. One colony is a new gene with unknown function. CONCLUSION: The successful cloning of gene of ALR interacting protein has paved the way for studying the physiological function of ALR and associated proteins.

Animals↗
PubMed2003

[Construction of subtracted cDNA library in human Jurkat T cell line induced by arsenic trioxide in vitro].

OBJECTIVE: To understand the differentially expressed genes in human T lymphocytes induced by arsenic trioxide (As(2)O(3)) and to explore mechanism of its immunotoxicity and immune suppression. METHODS: Human Jurkat T cell line was treated by arsenic trioxide (5 micromol/L, 24 h) in vitro, as a sample model. Then, the differentially expressed genes were cloned and the subtractive cDNA library from Jurkat T cell line was constructed by suppression subtractive hybridization (SSH). Polymerase chain reaction (PCR) and sequencing techniques were applied to identify positive clones. RESULTS: The forward subtracted cDNA library contained differentially expressed genes from Jurkat T cell line induced by arsenic trioxide was constructed, including 29 different gene fragments and only replicated one in the subtracted cDNA library identified by PCR and sequencing analysis. These gene sequences were 95%-100% analogous to the genes in public database (GenBank/EMBL). The cDNA library contained oxidative metabolic genes in mitochondria (triose phosphate dehydrogenase, NADH4, pyrophosphate synthase, 16S rRNA ribosome, succinate-CoA ligase and ATP synthase 6); transcriptional and translation genes poly (A) binding protein, t-RNA-guanine transglycoslase, ribosomal protein L23, ribosomal protein S15A, eukaryotic translation initiation factor 3, Rab interaction protein 5, splicing factor-arginine serine rich 5, and ADP-ribosylation factor-like 6 interacting protein), oxide stress related genes (ferritin high chain and high-mobility group protein 2); protein activating and signaling pathway related genes (casein kinase, serine kinase 2 and phosphatidylinositol-four-phosphate adaptor protein-1-associated protein); cell differentiation and apoptosis associated genes (NB4 cell apoptosis related protein and myeloid differentiation primary response protein) and five genes with unknown function (KIAA0092, CGI-147protein, GCI-35, nucleolar phosphoprotein Nopp34 and Mus muscular partial mRNA for hypothetical protein), as well as a novel gene unmatched to the sequence in GenBank. CONCLUSIONS: The forward subtracted cDNA library contained differentially expressed genes from Jurkat T cell line induced by arsenic trioxide was successfully constructed. And, genes not involved in previous research on arsenic were found. Results of analysis for these genetic function suggested that there should be many genes involved in process of T lymphocytes apoptosis or injury induced by arsenic trioxide and that there should still be many genes associated with arsenic that were not reported in the past.

Antineoplastic Agents↗
PubMed2003

[Studies on the constituents from the stems of Spatholobus suberectus].

OBJECTIVE: To investigate the constituents from the Stems of Spatholobus suberectus. METHOD: The chemical constituents were isolated by column chromatography and their strutures were identified on base of physical and spectral data. RESULT: Five compounds were isolated and identified as 2-methoxy-4-(2'-hydroxyethyl)-phenyl-1-O-beta-D-glucopyranoside (1), n-butyl-O-beta-D-fructo pyranoside (2), glycerol-alpha-pentacosanoate (3), betulinic acid (4) and hexacosanoic acid (5). CONCLUSION: The five compounds were obtained for the frist time from the stems of Spatholobus suberectus.

Fabaceae↗
PubMed2002

A critical role for IL-21 in regulating immunoglobulin production.

The cytokine interleukin-21 (IL-21) is closely related to IL-2 and IL-15, and their receptors all share the common cytokine receptor gamma chain, gammac, which is mutated in humans with X-linked severe combined immunodeficiency disease (XSCID). We demonstrate that, although mice deficient in the receptor for IL-21 (IL-21R) have normal lymphoid development, after immunization, these animals have higher production of the immunoglobulin IgE, but lower IgG1, than wild-type animals. Mice lacking both IL-4 and IL-21R exhibited a significantly more pronounced phenotype, with dysgammaglobulinemia, characterized primarily by a severely impaired IgG response. Thus, IL-21 has a significant influence on the regulation of B cell function in vivo and cooperates with IL-4. This suggests that these gammac-dependent cytokines may be those whose inactivation is primarily responsible for the B cell defect in humans with XSCID.

Animals↗
PubMed2002

Simultaneous determination of amino acids and carbohydrates by anion-exchange chromatography with integrated pulsed amperometric detection.

A direct, sensitive, simple and practical method for simultaneous determination of amino acids and carbohydrates by anion-exchange chromatography with integrated pulsed amperometric detection was developed. The retention behavior of amino acids and carbohydrates on the anion-exchange column and the detection of amino acids and carbohydrates at different integrated pulsed amperometric detection waveforms were investigated. The optimized gradient eluent conditions for analysis of 17 amino acids and nine carbohydrates were obtained. Separation time was 100 min. Detection limits for amino acids and carbohydrates were 5.2-207.1 nM under injection volume of 25 microl. The RSDs of peak area were 1.2-3.3%. The calibration graphs of peak area for the analytes were linear over about three orders of magnitude with a correlation coefficient of 0.9950-0.9999. The method was applied to determine amino acids and carbohydrates in a liquid condiment with satisfactory results.

Amino Acids↗
PubMed2002

Meiotic arrest and aneuploidy in MLH3-deficient mice.

MutL homolog 3 (Mlh3) is a member of a family of proteins conserved during evolution and having dual roles in DNA mismatch repair and meiosis. The pathway in eukaryotes consists of the DNA-binding components, which are the homologs of the bacterial MutS protein (MSH 2 6), and the MutL homologs, which bind to the MutS homologs and are essential for the repair process. Three of the six homologs of MutS that function in these processes, Msh2, Msh3 and Msh6, are involved in the mismatch repair of mutations, frameshifts and replication errors, and two others, Msh4 and Msh5, have specific roles in meiosis. Of the four MutL homologs, Mlh1, Mlh3, Pms1 and Pms2, three are involved in mismatch repair and at least two, Pms2 and Mlh1, are essential for meiotic progression in both yeast and mice. To assess the role of Mlh3 in mammalian meiosis, we have generated and characterized Mlh3(-/-) mice. Here we show that Mlh3(-/-) mice are viable but sterile. Mlh3 is required for Mlh1 binding to meiotic chromosomes and localizes to meiotic chromosomes from the mid pachynema stage of prophase I. Mlh3(-/-) spermatocytes reach metaphase before succumbing to apoptosis, but oocytes fail to complete meiosis I after fertilization. Our results show that Mlh3 has an essential and distinct role in mammalian meiosis.

Adaptor Proteins, Signal Transducing↗
PubMed2002

[Mutual interaction between hepatitis C virus core protein and translin, a recombination hotspot binding protein].

OBJECTIVE: To study the role of the core protein of hepatitis C virus (HCV) in HCV pathogenesis and investigate the molecular mechanism of this protein in tumorigenesis. METHODS: By using the yeast two hybrid system 3, the bait plasmids of the gene of the core protein of HCV was constructed and transfected into AH109 yeast strain. Then this transfected AH109 yeast was mated with Y187 yeast containing liver cDNA library plasmids and cultured on quadropledropout (QDO) medium covered with x-alpha-gal and assayed for alpha-gal activity. The blue colonies growing on QOD were collected to extract the plasmids to transform Escherichia coli. Plasmids were extracted from the bacterium and sequenced. After bioinformatic analysis translin, a recombination hotspot binding protein interacting with HCV core protein was found. To further prove the interaction between translin protein and HCV core protein translation was performed by using reticulocyte lysate and immunoprecipitation in vitro. RESULTS: Among the 30 positive colonies, a colony was translin. The interaction between HCV core protein and translin protein could be proved not only in yeast, but also in vitro. CONCLUSION: The core protein of HCV can interact with translin protein, this can explain partly the tumorigenesis of HCV.

Cell Transformation, Neoplastic↗
PubMed2002

[The study on heterogeneity of hepatitis B virus DNA].

OBJECTIVE: To investigate the HBV quasispecies groups in the patients with chronic HBV infection. METHODS: Specific primers ware synthesized according to HBV strain found in China, the preC/C gene, reverse transcriptase region, whole S region, X gene and whole genome ware amplified by PCR method from the serum of 18 patients with chronic HBV infection, and then the PCR products were subcloned into pGEM Teasy vectors. Positive clones with target sequences were selected out for sequencing. Sequence comparison of the selected clones ware made to find the difference. RESULTS: The homology between clones from one patient of preC/C gene, reverse transcriptase of polymerase region, whole S region, X gene and whole genome are 98.0% approximately 99.1%, 98.7% approximately 99.3%, 97.5% approximately 100%, 93.0% approximately 98.2% and 96.6% approximately 97.5%, respectively. There was a high-frequency A83 substitution and core antigen internal deletion (CID) in preC/C region. Substitution, deletion and frame-shift by insertion or deletion of short sequence were found in 4 open reading frames. Deletion in X gene (Core promoter, CP) will not only result in the polymorphism of X protein at the carboxyl end, but also regulate the expression of HBeAg. Coding sequence of truncated middle surface antigen and defective HBV genome could also be detected in this study. CONCLUSION: There are HBV quasispecies groups in patients with chronic HBV infection. Hot deletion region in X region (CP) will influence the prognosis of the HBV infection. Individually characterized substitutions in amino acid sequence of viral protein is worthy of further study.

Amino Acid Sequence↗
PubMed2002

Large scale molecular analysis identifies genes with altered expression in salivary adenoid cystic carcinoma.

Salivary gland cancers comprise a heterogeneous group of neoplasms whose biological and clinical characteristics differ considerably from those of mucosal squamous cell carcinomas of the head and neck. One of the most common subtypes, adenoid cystic carcinoma (ACC), is notable for its myoepithelial differentiation, proclivity for hematogenous spread, and slow but progressive clinical course. The molecular alterations that underlie its development and progression are poorly characterized. Here we used oligonucleotide microarray analysis to survey the expression of 8920 different human genes in 15 ACCs, one ACC cell line, and five normal major salivary glands. We observed expression of genes indicative of myoepithelial differentiation, as expected, including those whose protein products are components of basement membranes and extracellular matrix. Other genes that were highly ranked for their expression in ACC were those encoding the transcription factors SOX4 and AP-2 gamma, the latter of which also was overexpressed in ACC relative to 175 other carcinomas from 10 anatomical sites that we had previously profiled. Additional genes, which were highly expressed in ACC compared to the other carcinomas, included casein kinase 1, epsilon and frizzled-7, both members of the Wnt/beta-catenin signaling pathway. Our study documents for the first time the diverse spectrum of genes overexpressed in ACC and highlights gene products and pathways that in the future might be exploited as therapeutic targets for this cancer, which up until now, has shown limited response to chemotherapeutic approaches.

Carcinoma, Adenoid Cystic↗