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Biomedical subjects

Jun Xiong

Publications and source records attributed to Jun Xiong.

15 recordsLinked to original sources
PubMed2006

Long-term persistence of hepatitis B surface antigen and antibody induced by DNA-mediated immunization results in liver and kidney lesions in mice.

DNA-mediated immunization has been recognized as a new approach for prevention and treatment of hepatitis B virus (HBV) infection. However, the side effects of this approach have not been well described. Here we report that DNA-mediated immunization by intramuscular injection of plasmid DNA encoding HBV surface antigen (HBsAg) induced long-term persistence of HBsAg and HBsAg-specific antibody (anti-HBs) in the sera of the immunized BALB/c mice and resulted in liver and kidney lesions. The lesions persisted for 6 months after injection. Lesions were also found in normal mice injected with the sera from immunized mice, and in HBV-transgenic mice injected with anti-HBs antibody, or sera from immunized mice. Furthermore, lesions were accompanied by deposition of circulating immune complex (CIC) of HBsAg and anti-HBs antibody in the damaged organs. These results indicate that long-term persistence of HBsAg and anti-HBs in the immunized mice can result in deposited CIC in liver and kidney, and in development of lesions. The use of DNA containing mammalian replication origins, such as the plasmids used in this study, is not appropriate for human vaccines due to safety concerns relating to persistence of DNA; nevertheless, the safety of DNA-mediated immunization protocols still needs to be carefully evaluated before practical application.

Animals↗
PubMed2006

[Clonal culture of rat bone marrow-derived multipotential adult progenitor cells and study of their biological properties].

OBJECTIVE: To optimize the culture conditions for clonal isolation of rat bone marrow-derived multipotential adult progenitor cells (rMAPC) and identify their surface markers and differentiation potentials. METHODS: By using a low concentration of fetal bovine serum culture medium, rMAPCs were primarily isolated from bone marrow by attachment culture and clonal-like cells were selected by single cell limiting dilution. The surface antigens of the cloned rMAPC were analyzed by flow cytometry and immunocytochemistry. Multi-differentiation capacities were evaluated by lipoblasts and osteoblasts and neuroblasts differentiation induction. The expressions of Oct-4 and three embryonic germ layer markers were detected by RT-PCR. RESULTS: Single cell-derived rMAPC could be expanded to passage 20 in vitro which still maintained active proliferation ability. The expanded rMAPCs expressed CD71, alpha-SMA and vimentin, but not CD34, CD44 and CD45. About 83% of the rMAPCs was in the resting phase(G0 + G1) of cell cycle and 17% in S + G2 + M phase. They could be induced to differentiate into adipogenic cells, osteogenic cells and neural like cells. RT-PCR demonstrated that there were expressions of oct-4 gene and three embryonic germ layer markers on the rMAPCs. CONCLUSIONS: Cloned rMAPC can maintain the phenotypes of stem cell during in vitro culturing. It might be an potential adult stem cell source for therapeutic stem cell transplanting and tissue engineering.

Animals↗
PubMed2005

Increased level of polymerase III transcribed Alu RNA in hepatocellular carcinoma tissue.

There have been extensive observations that RNA containing repetitive elements accumulates in transformed cells and tumor tissues. In the present study, we first obtained result consistent with previous observations by in situ hybridization. Then we used primer extension analysis to determine the level of polymerase III directed Alu RNA and found an increased expression of Alu RNA in hepatocellular carcinoma.

Alu Elements↗
PubMed2005

Prokaryotic expression and biological activity analysis of human arresten gene.

To express recombinant arresten in Escherichia coli (E. Coli) and investigate its biological activity, prokaryotic expression vector of human arresten gene was constructed by gene engineering. Human arresten gene was amplified from recombinant plasmid pGEMArr by polymerase chain reaction (PCR), and inserted into prokaryotic expression vector pRSET containing T7 promoter. Restriction analysis and DNA sequencing verified that the arresten gene was correctly cloned into the expression vector. The recombinant plasmid pRSETAt was subsequently transformed into E. coli BL21 (DE3), and the target gene was expressed under induction of IPTG. SDS-PAGE analysis revealed that the recombinant protein with a molecular weight of 29 kD (1 kD = 0.992 1 ku) amounted to 29% of the total bacterial proteins. After purification and renaturation, the recombinant protein could significantly suppress the proliferation of human umbilical vein endothelial cells (HUVECs). These results suggested that the expression of a biologically active form of human arresten in the pRSET expression system laid a foundation for further study on the mechanistic insight into arresten action on angiogenesis and the development of powerful anti-cancer drugs.

Angiogenesis Inhibitors↗
PubMed2005

Effect of siRNA targeting survivin gene on the biological behavior of hepatocellular carcinoma.

To study the influence of siRNA targeting survivin gene on the biological behavior of hepatocellular carcinoma (HCC), one pair of 21bp reverse repeated. motifs of survivin target sequence with 9 spacers were synthesized and inserted into plasmid psilencer2. 1 to generate siRNA eukaryotic expression vector. After stable transfection into HepG2 cells, the biological behaviors of the survivin siRNA transfected HCC cells were observed. After the recombinant plasmid Psilence (+)-survivin was successfully constructed, survivin mRNA and protein expression inhibition ratio reached 73 % and 75% respectively compared to control groups. Transfected cells with survivin siRNA demonstrated significantly inhibited cell growth and increased apoptosis. Subsequent study in nude mouse model demonstrated lower succeeding rate in cells transfected with survivin siRNA and slow growth rate. The results elucidated the siRNA targeting survivin gene could specially suppress its expression in HepG2 cells and inhibit tumor cells growth both in vivo and in vitro. This provides a theoretical basis to turn the drug resistance in tumor cells.

Apoptosis↗
PubMed2005

[Construction of recombinant deltaN IkappaBalpha adenovirus and its suppression of NF-kappaB activity in A549 cells].

AIM: To explore the regulatory effect of deltaN IkappaBalpha gene on the activity of nuclear factor-kappaB(NF-kappaB). METHODS: Ser32-and Ser36-deleted IkappaBalpha gene (deltaN IkappaBalpha) was cloned into adenovirus vector, and a replication-defective recombinant deltaN IkappaBalpha adenovirus(Ad-deltaN IkappaBalpha) was generated. A549 cells were divided into three groups: LPS-stimulated groups, Ad-LacZ+LPS group and Ad-deltaN IkappaBalpha+LPS group. Ad-LacZ+LPS group and Ad-deltaN IkappaBalpha+LPS group were infected with Ad-LacZ and Ad-deltaN IkappaBalpha, respectively, two days before LPS stimulation. The NF-kappaB activity of A549 cells was detected by Western blot and electrophoretic mobility shift assay (EMSA). TNF-alpha and IL-6 in the culture supernatant were detecteded by ELISA. RESULTS: The activity of NF-kappaB and the levels of TNF-alpha and IL-6 from Ad-deltaN IkappaBalpha virus-infected A549 cells were significantly decreased as compared with that of LPS-stimulated group and Ad-LacZ+LPS group. CONCLUSION: The results indicated that deltaN IkappaBalpha may inhibit the activation of NF-kappaB and reduce the release of TNF-alpha and IL-6, suggesting the recombinant deltaN IkappaBalpha adenovirus may be used for anti-inflammatory therapy.

Adenoviridae↗
PubMed2005

[Terpenoids in root exudates of different allelopathic rice varieties].

In this paper, a strong allelopathic rice variety PI312777 and a weak allelopathic rice variety Lemont were used as test materials, and the root exudates of two rice varieties grown in the media of sand and soil were respectively collected by using circulation system approach. The terpenoids in ether-extracts were detected by GC-MS, and characterized by spectrum database. The results showed that some terpenoids such as limonene oxide, limonene dioxide, carvone oxide, carveol, and cedrol were detected in the ether-extracts. Different rice varieties had the similar kinds of terpenoids, but their existing modes and quantities were different. The differences between different various cultural methods and between rice varieties were further discussed.

Oryza↗
PubMed2005

[Allelopathy and resources competition of rice under different nitrogen supplies].

In order to explore the bio-interference of allelopathic rice with barnyardgrass under different nitrogen supplies, a new bioassay method, i.e., allelopathy-competition separation based (ACS) approach was recommended in this study. The results indicated that ACS could be successfully used to distinguish the rice allelopathy from its resources competition in rice-weed co-culture system, and to evaluate its response characteristics under different N supplies. The test rice accession PI312777 had a higher ability in interfering target weed barnyardgrass (BYD), represented by its stable and higher ability in resources competition, as well as its increasing allelopathic potential in suppressing companion weed BYD when the N supply decreased in the co-cultured system. The reverse was true in the case of rice accession Lemont, which had a lower allelopathic potential under all N supply levels, and a lower ability in resources competition under normal or rich N supply. But, Lemont had an obviously increased ability in resources competition under lower N supply, which was considered as the result of econiche competition in rice-weed system.

Echinochloa↗
PubMed2005

[Chemical components of root exudates from allelopathic rice accession PI312777 seedlings].

In this study, allelopathic rice accession PI312777 seedlings were grown on a paddy soil under near natural condition, and their root exudates were collected by using circulation method, with the solution collected from no seedlings- planted soil as the control. The ether extracts of the root exudates and soil solution were detected by GC-MS, and identified with the mass spectral database of NIST and WILEY Library. The results showed that there were 36 compounds in the rice root exudates, including 9 terpenoids (peak area 10.97%), 8 phenols or quinones (5.87%), 6 esters (10.68%), 3 aldehydes or ketones (1.44%), 4 heterocycles (68.04%), 2 alcohols (1.23%), 2 ethers (0.57%), and 2 others (1.20%). A distinctly similar structure was observed among the terpenoids and among the phenols or quinones. In the soil solution, 39 compounds were detected, and 7 of them were the same of the root exudates. The difference of the compounds in rice root exudates and soil solution, and the possible allelopathic mechanisms of these compounds were discussed in this paper.

Heterocyclic Compounds↗
PubMed2004

Human embryonic germ cells isolation from early stages of post-implantation embryos.

Human embryonic germ (hEG) cell is a very important alternative pluripotent stem cell resource. We describe the derivation of hEG cells from human embryonic fetal gonads over 6-8 weeks postconception. A large number of EG-like cell clumps were obtained at passage 1 and thus facilitated the following routine culture when the donor tissues were trypsinized with gentle pipetting and plated on feeder layer cells in the initial culture. Eight diploid hEG cell lines have been cultivated in vitro for extended periods while maintaining expression of markers characteristic of pluripotent stem cells. Human EG cells expressed transcription factor Oct4, a marker of pluripotency in mouse EG cells, at a high and steady level. Expression of markers indicative of differentiation along the three germ lineages was also observed in EBs. High level of alkaline phosphatase activity was shown in EG cells. These encouraging findings provide a starting point for potential applicability of hEG cells.

Alkaline Phosphatase↗
PubMed2004

Three-dimensional tracking of single secretory granules in live PC12 cells.

Deconvolution wide-field fluorescence microscopy and single-particle tracking were used to study the three-dimensional mobility of single secretory granules in live PC12 cells. Acridine orange-labeled granules were found to travel primarily in random and caged diffusion, whereas only a small fraction of granules traveled in directed fashion. High K(+) stimulation increased significantly the percentage of granules traveling in directed fashion. By dividing granules into the near-membrane group (within 1 microm from the plasma membrane) and cytosolic group, we have revealed significant differences between these two groups of granules in their mobility. The mobility of these two groups of granules is also differentially affected by disruption of F-actin, suggesting different mechanisms are involved in the motion of the two groups of granules. Our results demonstrate that combined deconvolution and single-particle tracking may find its application in three-dimensional tracking of long-term motion of granules and elucidating the underlying mechanisms.

Acridine Orange↗
PubMed2003

Expression of hepatitis B virus X protein in transgenic mice.

AIM: To establish a mice model harboring hepatitis B virus x gene (adr subtype) for studying the function of hepatitis B virus X protein, a transactivator of viral and cellular promoter/enhancer elements. METHODS: Expression vector pcDNA3-HBx, containing CMV promoter and hepatitis B virus x gene open reading fragment, was constructed by recombination DNA technique. Hela cells were cultured in DMEM and transfected with pcDNA3-HBx or control pcDNA3 plasmids using FuGENE6 Transfection Reagent. Expression of pcDNA3-HBx vectors in the transfected Hela cells was confirmed by Western blotting. After restriction endonuclease digestion, the coding elements were microinjected into male pronuclei of mice zygotes. The pups were evaluated by multiplex polymerase chain reaction (PCR) at genomic DNA level. The x gene transgenic mice founders were confirmed at protein level by Western blotting, immunohistochemistry and immunogold transmission electron microscopy. RESULTS: Expression vector pcDNA3-HBx was constructed by recombination DNA technique and identified right by restriction endonuclease digestion and DNA direct sequencing. With Western blotting, hepatitis X protein was detected in Hela cells transfected with pcDNA3-HBx plasmids, suggesting pcDNA3-HBx plasmids could express in eukaryotic cells. Following microinjection of coding sequence of pcDNA3-HBx, the embryos were transferred to oviducts of pseudopregnant females. Four pups were born and survived. Two of them were verified to have the HBx gene integrated in their genomic DNA by multiplex PCR assay, and named C57-TgN(HBx)SMMU1 and C57-TgN(HBx)SMMU3 respectively. They expressed 17KD X protein in liver tissue by Western blotting assay. With the immunohistochemistry, X protein was detected mainly in hepatocytes cytoplasm of transgenic mice, which was furthermore confirmed by immunogold transmission electon microscopy. CONCLUSION: We have constructed the expression vector pcDNA3-HBx that can be used to study the function of HBx gene in eukaryotic cells in vitro. We also established HBx gene (adr subtype) transgenic mice named C57-TgN (HBx)SMMU harboring HBx gene in their genome and express X protein in hepatocytes, Which might be a valuable animal system for studying the roles of HBx gene in hepatitis B virus life cycle and development of hepatocellular carcinoma in vivo.

Animals↗
PubMed2003

[Long-term effects and influence on facial structure of palatal distraction].

OBJECTIVE: The purpose of this study was to evaluate a new palatoplasty with persistent elastic distraction osteogenesis. METHODS: Twenty mongrel dog aged in 6 month were divided into two groups: the control (n = 10) and the experimental group (n = 10). The cleft palate model was made surgically in experimental dogs. The hard palate clefts were repaired with persistent elastic distraction osteogenesis. Then the animals were observed for an additional 12 weeks before sacrifice. Direct measurements was taken on dry skulls of the dogs and the data were analyzed statistically. RESULTS: For all experimental dogs, the clefts were closed after gradual distraction. No relapse and airway blocking occurred in observational period. There were no significant differences in the variables of facial length, height and width between the two groups (P > 0.05). The length of horizontal portion of hard palate in experimental group was significantly longer than that in the control (P < 0.01). CONCLUSION: There was no complication and disturbance on maxillofacial structure in repairing cleft palate with persistent elastic distraction osteogenesis. It is an effective and safe technique for repairing cleft palate in animal model.

Animals↗
PubMed2002

[Prokaryotic expression of endostatin and preparation of polyclonal antibody].

BACKGROUND & OBJECTIVE: The aim of this study was to express and purify human endostatin and to prepare polyclonal antibody of mouse anti-human endostatin. METHODS: The cDNA of endostatin was amplified by PCR, then recombined into prokaryotic expression vector and transformed into Escherichia coli BL21 for expression; the mice were immunized with purified products. RESULTS: Prokaryotic expression vector pQE-30 of human endostatin was successfully constructed; the expression product was gained after pQE-30 was transferred into BL21. After purified by Ni affinity chromatography, the product was identified to be a single component by SDS-PAGE. Western blot analysis showed that high titer mouse anti-human endostatin polyclonal antibody was successfully prepared. CONCLUSION: Highly purified expression product and prepared polyclonal antibody provide the necessary material for further study.

Animals↗