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Biomedical subjects

Jun Xu

Publications and source records attributed to Jun Xu.

At least 127 records · Page 7Linked to original sources
PubMed2005

EMBRYONIC FACTOR 1 encodes an AMP deaminase and is essential for the zygote to embryo transition in Arabidopsis.

Fusion of the egg and the sperm cells in plants produces a zygote that develops into an embryo. Screening of ethyl methanesulfonate-mutagenized populations of Arabidopsis led to the identification of EMBRYONIC FACTOR 1 (FAC1), a locus that gives a zygote-lethal phenotype when mutated. The FAC1 gene was identified by positional cloning and confirmed by a genetic complementation test against a T-DNA insertion allele. It encodes an AMP deaminase (AMPD) that is known in human and yeast to convert AMP to IMP to maintain the energy potential. Expression of FAC1 in a yeast AMPD mutant after removal of its N-terminal putative transmembrane domain complemented the mutant phenotype, suggesting a functional conservancy but a structural divergence through evolution. Although a low level of FAC1 expression was observed in all organs tested, using a reporter construct we observed a significantly increased FAC1 expression in the zygote, early embryo and endosperm. Furthermore, during somatic embryogenesis, a high level of FAC1 expression was observed in developing embryos including putative embryogenic cells. FAC1, therefore, represents one of the earliest expressed genes known in plants. It may act through AMP depletion to provide sufficient energy for the zygote to proceed through development.

AMP Deaminase↗
PubMed2005

Using tree-based recursive partitioning methods to group haplotypes for increased power in association studies.

Motivated by the increasing availability of high-density single nucleotide polymorphism (SNP) markers across the genome, various haplotype-based methods have been developed for candidate gene association studies, and even for genome-wide association studies. Although haplotype approaches dramatically reduce the multiple comparisons problem (as compared to single SNP analysis), even the number of existing haplotypes is relatively large, which increases the degrees of freedom and decreases the power for the corresponding test statistic. Grouping haplotypes is a way to reduce the degrees of freedom. We propose a procedure that uses a tree-based recursive partitioning algorithm to group haplotypes into a small number of clusters, and conducts the association test based on groups of haplotypes instead of individual haplotypes. The method can be used for both population-based and family-based association studies, with known or ambiguous phase information. Simulation studies suggest that the proposed method has the right type I error rate, and is more powerful than some existing haplotype-based tests.

Algorithms↗
PubMed2005

The mechanisms and functions of activity-dependent long-term potentiation of intrinsic excitability.

The efficiency of neural circuits can be enhanced not only by increasing synaptic strength but also by increasing neuronal intrinsic excitability. Three major types of activity-dependent long-term potentiation of intrinsic excitability (LTP-IE) have been well defined: decreased action potential (AP) threshold, reduced afterhyperpolarization (AHP), and attenuated dendritic propagation. The ionic basis and induction pathways for these three types of LTP-IE have been largely revealed recently. These intrinsic plasticities and their cooperation enrich the functions fulfilled by neurons, and may serve as a supplementary mechanism for learning and memory.

Action Potentials↗
PubMed2005

[Survey of the utilization and adverse effects of antibacterial drugs in patients admitted for respiratory diseases].

OBJECTIVE: To evaluate the utilization of antibacterial drugs and their adverse effects in patients admitted for respiratory disease based on medical record review. METHODS: The medical records of 141 inpatients admitted in 2002 for respiratory diseases were reviewed. The drug utilization index (DUI) and daily cost of antibacterial drugs were calculated, with also assessment of the adverse effects in relation to the drug use. RESULTS: The DUI ranged from 0.9 to 1.1 in 66.7% of the patients, and the daily cost of the antibacterial drugs was 317.8+/-194.3 RMB, with a total of 14 cases with adverse drug effects recorded. CONCLUSIONS: The utilization of antibacterial drugs was basically adequate in Nanfang Hospital though with occasional abuse of cefoperazone and sulbactam, inappropriate combination and high cost of the antibacterial drugs. More careful application of these drugs in old patients is stressed.

Adolescent↗
PubMed2005

Protein transduction domain of membrane penetrating peptide can efficiently deliver DNA and protein into mouse liver for gene therapy.

BACKGROUND: The development of a harmless and efficient nonviral gene delivery system that can facilitate the penetration of nucleic acids through the plasma membrane is a key to successful gene therapy. The aim of this study was to test a nonviral gene transferring vector's function of delivering DNA into liver cells to provide an important clue for gene transfer in liver gene therapy. METHODS: The complex of DNA and DNA delivering protein was injected into mice through their tail veins. Then the mice were killed and their liver tissue was sectioned. The gene transferring results were detected using a confocal laser scanning microscope. RESULTS: Fluorescence analysis indicated that both DNA-membrane penetrating peptide (MPP) complex and DNA- hepatocyte specific receptor binding domain (HSRBD)-MPP complex could go into liver cells. The fluorescence value of liver cells in the DNA- HSRBD-MPP group was higher than that in the DNA-MPP group. CONCLUSIONS: MPP can successfully deliver DNA and protein into cells, and MPP with a HSRBD can specifically deliver DNA into liver cells. These have laid a foundation for further study on the nonviral liver cell gene delivering system.

Animals↗
PubMed2005

[Immunopathology of hepatitis B virus transgenic mouse strain C57-TgN (adr2.0) SMMU].

AIM: To make immunopathological study of hepatitis B virus transgenic mice line C57-TgN (HBV adr2.0) SMMU. METHODS: Twenty transgenic C57-TgN mice of SPF grade and corresponding control mice C57BL/6 were used for the study. The expressions of CD3, CD4 and CD8 on lymphocytes in peripheral blood from transgenic and normal C57BL/6 mice were detected by flow cytometry. T lymphocyte subsets in the liver tissues from transgenic mice and hepatitis B patients were analyzed by EnVision staining. RESULTS: The expression of CD3, CD4 and CD8 on lymphocytes in peripheral blood from transgenic mice was lower than those from normal mice. The infiltrative mononuclear cells in the liver tissues of transgenic mice were mainly CD3+ CD4+ cells, and no CD8+ CD57+ cells was found. The infiltrative mononuclear cells in the liver tissues of human hepatitis B patients were mainly CD3+ CD4+ or CD3+ CD8+ cells. CONCLUSION: T cell subsets in the peripheral blood and liver tissues of transgenic mice C57-TgN (adr2.0) SMMU are different from those in human chronic hepatitis B patients.

Animals↗
PubMed2005

[Construction of DNMT1 siRNA stable expressing vector and evaluation of its silenced efficiency in blocking gene expression].

OBJECTIVE: To construct the specific stable expression and high efficiency small interfering RNA(siRNA) expression vector that can block DNMT1 gene function. METHODS: Using vector-based RNA interference technique, the authors constructed a vector to transcribe functional short interfering RNA (RNAi). After transfection by lipofectmine (TM) reagent, the treated cells were selected by G418. The expression levels of RNA and protein of DNMT1 were analyzed by reverse transcription polymerase chain reaction(RT-PCR) and Western blotting. The status of methylation of E-cadherin was analyzed by methylation-specific PCR(MSP). RESULTS: The expression level of endogenous DNMT1 mRNA in transfected SMMC-7721 cell lines with DNMT1 RNAi construct was 43% less than that in control cell 7721-pSU cell lines. The protein level in the former was about 10% less than that in the latter. The efficiency of the siRNA of DNMT1 was found to be higher than 90%. Demethylation of promoter of E-cadherin was obtained due to the inhibition of DNMT1. CONCLUSION: DNMT1 siRNA stable expressing vector was obtained by gene-recombined technology. There was no complete sameness between the levels of protein and RNA in gene silenced cell lines. The efficiency of the siRNA should be confirmed by Western-blotting.

Blotting, Western↗
PubMed2005

[Application of extended high frequency audiometry in the patients with chronic renal failure treated by hemodialysis].

OBJECTIVE: To explore the features of hearing changes in patients with renal insufficiency treated with hemodialysis. METHOD: Forty-nine patients with chronic renal failure ongoing hemodialysis and 66 normal controllers were enrolled in this study. RESULT: The changes of the averaged hearing thresholds of high frequency for hemodialysis subgroup were similar to those of the control group, but the impairment of the hearing was more severe. Compared with the control group, there was significant statistically differences in every age segments. CONCLUSION: The hearing impairment in patients with chronic renal failure treated with hemodialysis is characteristic by decreased in high frequency portion.

Adult↗
PubMed2005

[Relationship between the acquired multi-drug resistance of human large cell lung cancer cell line NCI-H460 by cisplatin selection and p53 mutation].

OBJECTIVE: To explore the role of p53 mutation in the development of acquired multi-drug resistance during lung cancer chemotherapy. METHODS: A resistance large cell lung carcinoma cell line (H460/DDP) was established by high dose (50 micromol/L) cisplatin intermittent selection from its parental cell NCI-H460 that had wild type p53 (wtp53). Several multi-drug resistant proteins (MRP) including lung relative protein (LRP), P-gp, MRP, glutathione transferase-pi, topoisomerase II and P53 were checked by immunocytochemistry. Immunofluorescence was used to check the phosphoration of P53. p53 cDNA was amplified and sequenced. The H460/DDP cells were transected with plasmid pShuttle-CMV-wtp53 cDNA and measurement of drug sensitivity was performed after transfection. RESULTS: The resistance index to cisplatin and carboplatin in H460/DDP cell line was 10.21 and 9.98 respectively, and the cell line also exhibited cross-resistance to 5-fluorouracil, etoposide, methotrexate, adriamycin, epirubicin, bleomycin and novantrone, except for taxol. It was found that P53 protein translocated from nuclear to cytoplasm and could not phosphorate after the stimulation of cisplatin. LRP was expressed increasingly and other proteins showed insignificant changes. Sequencing showed an important insertion "t" after 277 bp on the gene level. H460/DDP cells transfected with plasmid pShuttle-CMV-wtp53 cDNA reversed partly (53.2%) the resistance to cisplatin/carboplatin, compared to the H460/DDP cells transfected with blank vector. CONCLUSIONS: p53 mutation induced by cisplatin/carboplatin might play an important role in the development of acquired multi-drug resistance of lung cancer chemotherapy. wtp53 substitute therapy during chemotherapy may be an effective method to overcome the acquired drug resistance.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2005

[Roles of mutant p53 gene in malignant phenotypes and resistance to drugs in anti-7,8-dihydrodiol-9,10-epoxide benzo(a)pyrene-induced lung cancer cells].

OBJECTIVE: To study the role of mutant p53 gene induced by anti-7,8-dihydrodiol-9,10-epoxide benzo(a)pyrene (BPDE) in the development of lung cancer and the effects of wild-type p53 substitution on malignant phenotype and resistance to drugs. METHODS: BPDE-induced human lung cancer cells (16HBE, a human bronchial epithelial cell line, treated by BPDE) with mutant p53 gene were transfected with pShuttle-cmv-wild p53, followed by soft-agar colony formation assay and cell growth assay. Genome DNAs were extracted from those cells after transfection for detection of apoptosis. Sensitivity of the cells to drugs was also detected simultaneously. RESULTS: It was shown that exogenous wild-type p53 transfection inhibited colony formation of the lung cancer cells with mutant p53 gene and induced cell growth arrest and cell apoptosis. In addition, the lung cancer cells transfected with wild-type p53 gene showed enhanced sensitivity to adriamycin (ADM) to which the cells before transfection was resistant. CONCLUSIONS: p53 mutation plays an important role in the development and progress of lung cancer, as well as in multi-drug resistance in the management of lung cancer chemotherapy. Wild-type p53 substitution therapy may enhance the sensitivity of lung cancer to chemical drugs.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed2005

Visible light induced photodegradation of organic pollutants on nitrogen and fluorine co-doped TiO2 photocatalyst.

The nitrogen and fluorine co-doped TiO2 polycrystalline powder was synthesized by calcinations of the hydrolysis product of tetrabutyl titanate with ammonium fluoride. Nitrogen and fluorine co-doping causes the absorption edge of TiO2 to shift to a lower energy region. The photocatalytic activity of co-doped TiO2 with anatase phases was found to be 2.4 times higher than that of the commercial TiO2 photocatalyst Degussa P25 for phenol decomposition under visible light irradiation. The co-doped TiO2 powders only contain anatase phases even at 1000 degrees C. Apparently, ammonium fluoride added retarded phase transformation of the TiO2 powders from anatase to rutile. The substitutional fluorine and interstitial nitrogen atoms in co-doped TiO2 polycrystalline powder were responsible for the vis light response and caused the absorption edge of TiO2 to shift to a lower energy region.

Absorption↗
PubMed2005

[Effects of self-concept on test anxiety level among sophomores in a medical college].

OBJECTIVE: To explore the effects of self-concept on the test anxiety among sophomores in a medical college. METHODS: Using the test anxiety questionnaire and English-learning self-concept scale, we examined the relationship between test anxiety and self-concept of the sophomores in a medical college. RESULTS: All the dimensions of self-concept were significantly related to test anxiety, among which the general self-concept, academic self-concept and English-learning self concept were important factors. CONCLUSION: Enhancement of general self-concept, academic self-concept and English-learning self concept are effective means to alleviate test anxiety of the students.

China↗
PubMed2005

[Study on the clinical significance of plasma adrenomedullin and brain natriuretic polypeptide in the patients with chronic cor pulmonale on highland].

OBJECTIVE: To study the clinical significance of plasma adrenomedullin (ADM) and brain natriuretic polypeptide (BNP) in the patients with chronic cor pulmonale on highland (HACCP). METHODS: The levels of ADM and BNP in plasma of 44 patients with HACCP in the acute and in the remission stages were determined with radioimmunoassay. Their correlations with partial pressure of oxygen in arterial blood (PaO(2)), endothelin-1 (ET-1), and the ratio of right ventricular pre-ejection time to the pulmonary flow acceleration time (RVPEP/AT), which reflected the degree of pulmonary hypertension, were investigated. Twenty healthy subjects served as a normal control group. RESULTS: The levels of ADM [(38.8+/-7.2)ng/L and (26.2+/-5.3)ng/L] and BNP [(81.4+/-13.8)ng/L and (58.9+/-9.3)ng/L] in the acute and remission stages of cor pulmonale groups were both significantly higher than those in the normal control group [(15.0+/-3.2)ng/L, (38.6+/-3.4)ng/L, respectively, all P<0.01]. The levels of ADM and BNP in acute stage were both significantly higher than those in remission stage (both P<0.01). In the acute and in the remission stages, the levels of ADM in plasma were negatively correlated with PaO(2) (r(a)=-0.826, P<0.01; r(r)=-0.783, P<0.01), positively correlated with ET-1 (r(a)=0.755, P<0.01; r(r)=0.668, P<0.01) and RVPEP/AT ratio (r(a)=0.788, P<0.01; r(r)=0.734, P<0.01). In the acute and in the remission stages, the levels of BNP in plasma were negatively correlated with PaO(2) (r(a)=-0.787, P<0.01; r(r)=-0.554, P<0.01), positively correlated with ET-1 (r(a)=0.725, P<0.01; r(r)=0.679, P<0.01) and RVPEP/AT ratio (r(a)=0.771, P<0.01; r(r)=0.722, P<0.01). CONCLUSION: The study suggests that ADM and BNP are involved in the pathophysiological process of HACCP in the patients and may play a compensatory role in the disease.

Adrenomedullin↗
PubMed2005

[Analysis of 994(G--> T) mutation in the plasma platelet-activating factor acetylhydrolase gene in the patients with cerebral infarction].

OBJECTIVE: To investigate the relationship between plasma platelet-activating factor acetylhydrolase (PAF-AH) gene 994(G--> T) mutation in exon 9 and the patients with cerebral infarction in Chinese Hans. METHODS: The authors conducted a case-control study including 108 patients in three groups (atherosclerotic cerebral infarction group, lacunar infarction group and cerebral embolism group) and 215 normal subjects as controls. Genomic DNA was analyzed for the mutant allele by a specific polymerase chain reaction. RESULTS: The frequency of the mutant genotype in the 102 patients with cerebral infarction was 35.19%(32.41% heterozygotes and 2.78% homozygotes), and was 38.10%(34.92% heterozygotes and 3.18% homozygotes) in the atherosclerotic cerebral infarction group, being all significantly higher than the control group's 20.46% (18.60% heterozygotes and 1.86% homozygotes)(P< 0.01); however, the frequencies of the mutant genotype in the lacunar infarction group and cerebral embolism group were 32.35% (29.41% heterozygotes and 2.94% homozygotes) and 27.27% (27.27% heterozygotes and 0 homozygotes) respectively, being not statistically different from those of the controls (P> 0.05). CONCLUSION: These findings show that the 994(G--> T) mutation of plasma PAF-AH gene may be an independent risk for atherosclerotic cerebral infarction, but not for lacunar infarction.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed2005

[Effects of airway epithelium injury on the transdifferentiation of sub-epithelial fibroblasts and its role in the development of airway hyperresponsiveness in asthma].

OBJECTIVE: To address the possible role of injured airway epithelium in initiating transdifferentiation of sub-epithelial fibroblasts into myofibroblasts and accelerating cell proliferation in sub-epithelial fibroblasts, which may be involved in airway hyperresponsiveness in asthma. METHODS: Human primary cultured sub-epithelial fibroblasts were co-cultured with human bronchial epithelial cells (16HBE) which were treated with lipopolysaccharide (LPS) plus mechanical scratch prior to co-culture. The procedure was also performed in the presence or absence of endothelin (ET) receptor A inhibitor (BQ123), transforming growth factor-beta(1) (TGF-beta(1)) neutralized antibody, respectively or simultaneously, followed by immunostaining, Western blotting and bromodeoxyuridine (BrdU) incorporation respectively to detect alpha-SMA expression and cell proliferation in the co-cultured sub-epithelial fibroblasts. Using the inhibitors specific for mitogen-activated protein kinases (MAPKs) pathways, the role of MAPKs pathways in activating the expression of alpha-SMA was evaluated. In addition, the interaction between matrix metalloproteinases (MMPs) and ET-1 was investigated by cell transfection with anti-ET-1 converting enzyme (anti-ECE) mRNA expression plasmid followed by gelatin zymography analysis. RESULTS: 16HBE treated with LPS plus mechanical injury induced alpha-SMA expression in sub-epithelial fibroblasts and accelerated BrdU incorporation in the cells. BQ123, TGF-beta(1) neutralized antibody, specific inhibitors for p38 MAPK and extracellular signal-regulated kinase 1/2 (ERK1/2) were able to block the induction respectively to a certain extent. Phosphorylated p38 MAPK and ERK1/2 were detected in the sub-epithelial fibroblasts 10 min after being co-cultured with injured 16HBE. Compared to normal control (16HBE transfected with pEGFPN(2)) or those cells transfected with anti-ECE mRNA expression plasmids, ET-1 released from the 16HBE cells transfected with pEGFPN(2) into supernatants were increased significantly after the treatment described as above: 16HBE pre-transfected with pEGFP-N(2) expression plasmid before being treated with mechanical scrape plus LPS stimulation: (15.00 +/- 0.86) pg/ml; 16HBE pre-transfected with anti-ECE expression plasmid before being treated with mechanical scrape plus LPS stimulation: (7.57 +/- 0.94) pg/ml (all P < 0.01). At the same time, the activities of MMP-2 and MMP-9 were enhanced. CONCLUSIONS: Injured airway epithelial cells induced the transdifferentiation of sub-epithelial fibroblasts into myofibroblasts, which may be mediated by ET-1 and TGF-beta(1) through MARKs pathways such as p38 MAPK and ERK 1/2.

Actins↗
PubMed2005

Pathogenesis of acute lung injury in rats with severe acute pancreatitis.

BACKGROUND: Acute lung injury (ALI) is the most common and severe complication of severe acute pancreatitis (SAP). The elucidation of the mechanism of ALI contributes to the diagnosis and treatment of the illness. In this study, we studied the pathogenesis of ALI in rats with severe acute pancreatitis. METHODS: The rats were sacrificed at 1, 3, 5, 6, 9 and 12 hours after the establishment of the model of SAP. Pancreas and lung tissues were obtained for pathological study, and examination of microvascular permeability and myeloperoxidase (MPO) examination. The gene expressions of tumor necrosis factor-alpha (TNF-alpha) and intercellular adhesion molecule-1 (ICAM-1) in the pancreas and lung tissues were detected by reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: After the establishment of the SAP model, the degree of pancreatic and lung injury increased gradually along with the gradual increase of MPO activity and microvascular permeability. Gene expressions of TNF-alpha and ICAM-1 in the pancreas rose at 1 hour and peaked at 7 hours. In contrast, their gene expression in the lungs rose slightly at 1 hour and peaked at 9-12 hours. CONCLUSION: An obvious time window existed between SAP and lung injury, which is beneficial to the early prevention of the development of ALI.

Acute Disease↗
PubMed2005

Identification of potential genes regulated by DNA methyltransferase 3B in a hepatocellular carcinoma cell line by RNA interference and microarray analysis.

Whether DNA methyltransferase 3B (DNMT3B) is deregulated in hepatocellular carcinoma cell lines is still unclear. The expression levels of DNMT3B protein in normal liver cell line, pericacinoma cell line and hepatocellular carcinoma cell lines were compared by both Western blotting and immunocytochemistry. Long-term downregulated DNMT3B in a hepatocellular carcinoma cell line SMMC-7721 was achieved using a RNAi recombinant plasmid. The suppression of DNMT3B induced by RNA interference was confirmed using semi-quantitative RT-PCR and Western blotting. High throughput cDNA microarray was used to analyze the expression profiling of downstream genes of DNMT3B displayed in the treated cell lines and control. In the result,DNMT3B in hepatocellular carcinoma cell lines was expressed at a significantly higher level compared to those in pericacinoma cell line and normal liver cell line. A specific DNMT3B siRNA stably expressed from a plasmid vector effectively suppressed the expression of DNMT3B in SMMC-7721 cell line. By microarray analysis,26 downregulated genes and 115 upregulated genes have been identified in the DNMT3B knockdown cell line,including some important developmental genes and tumor-related genes such as SNCG, NOTCH1, MBD3, WNT11, MAOA and FACL4. The discovery showed DNMT3B was over-expressed in most hepatocellular carcinoma cell lines examined and may be linked to the carcinogenesis of hepatocytes. An array of candidate genes that are involved in the action of DNMT3B have been identified,including those related to development.

Carcinoma, Hepatocellular↗