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Biomedical subjects

Jun Gu

Publications and source records attributed to Jun Gu.

67 records · Page 4Linked to original sources
PubMed2003

Labeling embryonic stem cells with enhanced green fluorescent protein on the hypoxanthineguanine phosphoribosyl transferase locus.

OBJECTIVE: To label embryonic stem (ES) cells with enhanced green fluorescent protein (EGFP) on the hypoxanthineguanine phosphoribosyl transferase (HPRT) gene locus for the first time to provide a convenient and efficient way for cell tracking and manipulation in the studies of transplantation and stem cell therapy. METHODS: Homologous fragments were obtained by polymerase chain reaction (PCR), from which the gene targeting vector pHPRT-EGFP was constructed. The linearized vector was introduced into ES cells by electroporation. The G418(r)6TG(r) cell clones were obtained after selection with G418 and 6TG media. The integration patterns of these resistant cell clones were identified with Southern blotting. RESULTS: EGFP expressing ES cells on the locus of HPRT were successfully generated. They have normal properties, such as karyotype, viability and differentiation ability. The green fluorescence of EGFP expressing cells was maintained in propagation of the ES cells for more than 30 passages and in differentiated cells. Cultured in suspension, the "green" ES cells aggregated and formed embryoid bodies, retaining the green fluorescence at varying developmental stages. The "green" embryoid bodies could expand and differentiate into various types of cells, exhibiting ubiquitous green fluorescence. CONCLUSIONS: This generation of "green" targeted ES cells is described in an efficient protocol for obtaining the homologous fragments by PCR. Introducing the marker gene in the genome of ES cells, we should be able to manipulate them in vitro and use them as vehicles in cell-replacement therapy as well as for other biomedical and research purposes.

Animals↗
PubMed2002

Rapid detection of IgH/BCL2 rearrangement in follicular lymphoma by interphase fluorescence in situ hybridization with bacterial artificial chromosome probes.

Follicular lymphomas (FLs) can be difficult to diagnose on aspirated specimens since the architectural pattern is not present. FLs characteristically have rearrangements in the IgH and BCL2 genes resulting from the reciprocal t(14;18) (q32; q21) translocation. Because of the dispersed distribution of breakpoints, fluorescence in situ hybridization (FISH) using genomic probes that span or flank the breakpoints is ideal for detecting this rearrangement in fine-needle aspiration (FNA) biopsies. To develop a set of probes, a bacterial artificial chromosome library was screened and the clones were mapped by fiber FISH. The probes were produced by the direct incorporation of fluorochrome-labeled nucleotides. The colocalization base FISH assay was applied to Cytospin preparations from FNA biopsies of lymph nodes from 26 patients with FL and 10 patients without FL. In those with FL, the percentage of cells with at least one IgH/BCL2 fusion signal ranged from 22% to 100% (mean, 63%), which was statistically significantly higher than that in FL-negative samples (mean, 2.7%). The probes demonstrated a significantly lower cutoff value (7%) in normal controls and effectively reduced the false-positive rate in FL-negative cases. These results were confirmed with fiber FISH assays on the same specimens. This interphase FISH assay is rapid and reliable for detecting rearrangements in the IGH/BCL2 gene, thereby aiding in the diagnosis of FL on FNA biopsy specimens.

Chromosomes, Artificial, Bacterial↗
PubMed2002

Differentiation of embryonic stem cell to astrocytes visualized by green fluorescent protein.

Green fluorescent protein (GFP) gene was transfected and expressed in murine embryonic stem (ES) cells under the control of the astrocyte-specific glial fibrillary acidic protein (GFAP) promoter. Stably transfected cells were characterized by immunohistochemistry and by fluorescence microscopy. Cells containing GFP were differentiated to Type I and Type II astrocytes after induction by all-trans retinoic acid. Differentiated cells were expressed GFP and visualized by fluorescence microscopy. Differentiated cells expressed GFP were correlated with the expression of GFAP and morphological change. It demonstrates that the cell line expressed GFP can be used to trace the morphological changes of astrocytes during differentiation, and further for the isolation of astrocytes from the mixed cells differentiated from ES cell.

Animals↗
PubMed2002

Genetic polymorphisms of the human CYP2A13 gene: identification of single-nucleotide polymorphisms and functional characterization of an Arg257Cys variant.

Human cytochrome P450 2A13 (CYP2A13), which is highly efficient in the metabolic activation of a major tobacco-specific carcinogen, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), may play important roles in xenobiotic toxicity and tobacco-related tumorigenesis in the respiratory tract. The aim of this study was to identify any genetic polymorphisms of the CYP2A13 gene, which may alter the metabolic capacities of the enzyme. Polymerase chain reaction (PCR) single-strand conformational polymorphism analysis was used to identify single-nucleotide polymorphisms (SNPs) in all of the exons and at the exon-intron boundaries, and PCR-restriction fragment length polymorphism analysis and DNA sequencing were used to determine the frequencies of the newly identified variant alleles in the four major ethnic groups. Blood spot DNA from more than 100 individuals was used for these analyses. Seven variant alleles were found, but only one SNP was detected in the coding region, in exon 5, leading to an Arg257Cys amino acid change. The frequencies of the Arg257Cys allele in white, black, Hispanic, and Asian individuals are 1.9%, 14.4%, 5.8%, and 7.7%, respectively. Functional analysis of the variant protein was performed following its heterologous expression. The Arg257Cys variant was 37 to 56% less active than the wild-type Arg-257 protein toward all substrates tested. With NNK, Cys-257 had higher K(m) and lower V(max) values than did Arg-257, with a >2-fold decrease in catalytic efficiency. The Arg257Cys mutation could provide some protection against xenobiotic toxicity in the respiratory tract to individuals who are homozygous for the Cys-257 allele.

Amino Acid Substitution↗
PubMed2002

Human glucagon gene promoter sequences regulating tissue-specific versus nutrient-regulated gene expression.

The glucagon-like peptides (GLPs) are synthesized and secreted in a nutrient-dependent manner in rodents; however, the factors regulating human GLP-1 and GLP-2 biosynthesis remain unclear. To understand how nutrients regulate human proglucagon gene expression, we studied the expression of a human proglucagon promoter-growth hormone (GH) transgene in 1.6 human glucagon-GH transgenic mice. Fasting-refeeding significantly decreased and increased the levels of circulating mouse insulin and transgene-derived hGH (P < 0.05 fasting vs. refeeding) and decreased and upregulated, respectively, the levels of endogenous mouse proglucagon RNA in the ileum but not in the jejunum or colon. High-fiber feeding significantly increased the levels of glucose-stimulated circulating hGH and upregulated levels of mouse intestinal proglucagon gene expression in the jejunum, ileum, and colon (P < 0.05, 0 vs. 30% fiber diet). In contrast, neither fasting-refeeding nor a high-fiber diet upregulated the expression of the human proglucagon promoter-hGH transgene. These findings demonstrate that human proglucagon gene regulatory sequences specifying tissue-specific expression in gut endocrine cells are not sufficient for recognition of energy-derived signals regulating murine glucagon gene expression in enteroendocrine cells in vivo.

Animal Nutritional Physiological Phenomena↗
PubMed2002

[Expression and identification of specific autoantigens in autoimmune hepatitis].

OBJECTIVE: To express and identify soluble liver antigen (SLA) and cytochrome P-450 (CYP 2D6). METHODS: SLA cDNA and CYP 2D6 cDNA were obtained from human liver tissue poly (A)+RNA by RT-PCR. The cDNAs were inserted into fusion expression vector PQE-30 site of BamH I and Hind III. SLA and CYP 2D6 were identified by the SDS-PAGE and Western blot. RESULTS: SDS-PAGE analysis showed that there was a very strong stained band at about 47 kd and 50 kd, respectively. The products could specifically band to anti-SLA or anti-CYP 2D6 autoantibodies. CONCLUSIONS: The clone and expression of SLA and CYP 2D6 provide useful substances for the diagnosis and research of pathogenesis on autoimmune hepatitis.

Autoantigens↗
PubMed2002

Rehabilitation therapy for short bowel syndrome.

OBJECTIVE: To investigate the effect of rehabilitation therapy for short bowel syndrome on patient nutritional status and intestinal adaptation. METHODS: The rehabilitation therapy included enteral or parenteral nutrition, glutamine, recombinant human growth hormone and rehabilitative diet. From January 1997 to July 2000, twenty - seven patients with short bowel syndrome received the treatment. The average age of the patients was 38.5 +/- 19.3 years, and the length of residual small intestine ranged from 15 to 80 cm, with an average of 46.8 +/- 23.4 cm. The ileocecal valve was preserved in 14 cases, and the average time between the onset of short bowel syndrome and the rehabilitation therapy was 86 +/- 105 days. RESULTS: After the treatment, nutritional status of the patients improved markedly, and intestinal absorptive capacity improved. Eight patients were followed up for more than 2 years, among whom 4 (50%) were weaned from total parenteral nutrition. Thirteen patients were followed up for more than 1 year, and 10 patients (76.9%) were weaned from total parenteral nutrition. CONCLUSIONS: Rehabilitation therapy for short bowel syndrome can improve patient nutritional status effectively and promote intestinal adaptation, providing a new hope for these patients. The therapeutic effects are related to the length of the residual small intestine, patients age and duration between massive intestinal resection and start of the treatment. Early initiation of rehabilitation therapy promotes intestinal adaptation and increases patients ability to wean from total parenteral nutrition.

Adolescent↗
PubMed2002

M2 muscarinic receptor of spinal cord mediated increase of nNOS expression in locus coeruleus during morphine withdrawal.

AIM: To investigate the effects of different muscarinic receptor (M) subtypes in the spinal cord on the scores of naloxone-precipitated morphine-withdrawal symptoms and the changes of nNOS expression in locus coeruleus (LC). METHODS: nNOS immunohistochemistry, intrathecal injection (it), and antisense oligonucleotides (AS-ONs) techniques were used. RESULTS: Intrathecal injection of M2-antisense oligonucleotides (M2-AS) decreased the scores of morphine withdrawal symptoms. M1-AS attenuated morphine-withdrawal symptoms, but the effect was less than that of M2-AS. The expression of nNOS positive neurons in the LC increased in morphine-dependent rats and increased to a greater extent during morphine withdrawal. Intrathecal injection of M2-AS inhibited the increase of nNOS expression in LC during morphine-withdrawal, but there was no effect in case of M1-AS. CONCLUSION: M2 muscarinic receptor of spinal cord mediated the increase of nNOS expression in LC during morphine withdrawal.

Animals↗
PubMed2002

Effect of emodin on proliferation and differentiation of 3T3-L1 preadipocyte and FAS activity.

OBJECTIVE: To study the effects of emodin on proliferation and differentiation of 3T3-L1 preadipocyte and the possible mechanism. METHODS: Cell proliferation was determined by MTT spectrophotometry, cell differentiation was determined by Oil Red O staining,and fatty acid synthase (FAS) activity was determined by spectrophotometry. RESULTS: Emodin promoted proliferation of 3T3-L1 preadipocyte at low concentration and inhibited the proliferation at high concentration in a dose-related manner. In contrast, it inhibited cell differentiation into adipocyte at low concentration in a dose-related manner. In vitro emodin inhibited the activity of FAS in a dose-related manner. CONCLUSIONS: The effects of emodin on 3T3-L1 cell's proliferation and differentiation are dose dependent. Emodin inhibits the activity of FAS. Our results suggest that emodin should have a potential to serve as a fat-reducing drug.

3T3 Cells↗
PubMed2002

[mRNA expression of muscarinic receptors in spinal cord and brainstem in morphine dependent rats].

AIM: To observe mRNA expression of muscarinic acetylcholine receptors in spinal cord and brainstem in morphine dependent or withdrawal rats. METHODS: The mRNA expression level of m1, m2, m3, m4 and m5 were determined by RT-PCR, the beta-actin mRNA expression was used as internal control. RESULTS: The mRNA level of m1, m2, m3, m4 and m5 in spinal cord and m1 and m2 in brainstem were increased significantly during morphine dependence, and the levels of m1, m2, m3 and m4 in spinal cord and m1 in brainstem were decreased 1 h after the injection of naloxone (4 mg.kg-1, i.p.) in morphine dependent rats. Either scopolamine (0.5 mg.kg-1) or pirenzepine (10 mg.kg-1) was shown to significantly decrease the morphine withdrawal symptoms in rats. The levels of m1, m2, m3 and m5 in spinal cord were increased by pretreatment with pirenzepine and the levels of m2, m3 and m4 in spinal cord were increased by pretreatment with scopolamine. CONCLUSION: The adaptive expression of muscarinic receptors at spinal and supraspinal levels play important role in mediating morphine dependence and withdrawal in rats.

Animals↗
PubMed2002

[Fine mapping of susceptibility genes loci within chromosome 1 in Chinese Han families with type 2 diabetes].

OBJECTIVES: To confirm previous whole-genome scan results of mapping type 2 diabetes susceptibility genes in chromosome 1 in Northern Chinese Han population by conducting a new genome scan with both an enlarged number of type 2 diabetes families and a new set of microsatellite markers. METHODS: A genome scan method was applied. After multiplexed PCR, electrophoreses, genescan and genotyping analysis, size informations for all loci were obtained, and a further study was done using both parametric and non-parametric linkage analysis to calculate the P-values and Z-values of these loci. RESULTS: A total of 34 microsatellite markers distributed within 5 regions along chromosome 1 were surveyed, and 12,000 genotypes were screened. Evidence of linkage with diabetes was identified for 8 of the 34 loci (all the P-values of the 8 loci distributed in 3 regions were lower than 0.05, and the highest Z-value was 2.17). Interestingly, all the 5 markers at the P terminal 1p36.3-1p36.23 region, spanning a long range of 16.9 cM, suggested to be linked with the disease. The results of the other two regions were not consistent with the previous ones. CONCLUSIONS: The study results have confirmed those gained in the previous genome-wide scan. The fact that all 5 loci at the P terminal region displayed linkage with diabetes suggests that more than 1 susceptibility gene may reside in this region.

Asian People↗
PubMedDate not supplied

Targeting of hepatoma cell and suppression of tumor growth by a novel 12mer peptide fused to superantigen TSST-1.

Hepatocellular carcinoma (HCC), one of the most common and malignant tumors worldwide, is unresponsive to any of the available therapies. Using intact HCC cells as therapeutic targets, we isolated a novel peptide, denoted HCC79 (KSLSRHDHIHHH), from a phage display peptide library. HCC79 can bind to hepatoma cell membranes with high affinity and specificity. Remarkably, competitive binding assays demonstrated that HCC79 competed with HAb25, a specific antibody for HCC, in binding to hepatoma cells. The corresponding synthetic peptide did not inhibit tumor proliferation directly, but repressed tumor invasion significantly in a cell migration assay. Moreover, we explored the potential of the selected peptide to deliver a superantigen (SAg) to cancer cells, to attain a significant cell-targeting effect. When the peptide is fused to the TSST-1 SAg, the resulting fusion protein could bind to hepatoma cells with high affinity in vitro and improved the tumor inhibition effect by activating T lymphocyte cells in vitro and in vivo, compared with TSST-1 alone. Taken together, our results indicate that this peptide and its future derivatives may have the potential to be developed into highly specific therapeutic agents against cancer.

Amino Acid Sequence↗