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Biomedical subjects

Chen Dong

Publications and source records attributed to Chen Dong.

At least 37 records · Page 2Linked to original sources
PubMed2006

[Effects of different vectors and gene fragments on antigen expression of hepatitis E virus DNA immunization].

AIM: To investigate the effects of different vectors and gene fragments on antigen expression of hepatitis E virus (HEV) DNA immunization. METHODS: Gene fragments encoding p166 and p179, which contain the neutralization antigenic epitopes of a Chinese strain of HEV genotype IV, were cloned into two different eukaryotic expression vectors (pTR421 and pCDNA3.1), respectively. The in vitro expression level of p166 and p179 in HepG2 cells transfected by each of the recombinant plasmids with lipofectamine2000 was examined by means of immunofluorescence and Western blot. Meanwhile, the in vivo expression level in muscles of mice was examined with immunohistochemistry staining. RESULTS: Four recombinant plasmids, pTR421-166, pTR421-179, pCDNA3.1-166 and pCDNA3.1-179, were constructed successfully and confirmed correct with restriction endonuclease analysis and nucleotide sequencing. The antigen expression was only detected in HepG2 cells transfected by pTR421-179 and in myocytes of the mice injected with pTR421-179. Neither in vitro nor in vivo antigen expression was detected with pTR421-166 although p166 was only 13 amino acids shorter than p179 at N terminus. Neither pCDNA3.1-166 nor pCDNA3.1-179 was expressed in vitro and in vivo. CONCLUSION: Selection of the vectors and gene fragments is critical to HEV gene expression and HEV DNA vaccine.

Animals↗
PubMed2006

[Heme oxygenase-1 expression and apoptosis induced by cadmium in human embryon kidney cells].

OBJECTIVE: To investigate apoptosis and expression of heme oxygenase-1 (HO-1) induced by cadmium in human embryonic kidney cells (HEK239T). METHODS: The MTT method was used for determining the cell proliferation activity. The apoptosis was determined by the flow cytometry. The HO-l mRNA expression and protein level were detected by RT-PCR method and Western blot respectively. RESULTS: The ratios of apoptosis in HEK239T cells were 11.90% +/- 0.28%, 9.27% +/- 1.73%, 9.79% +/- 0.67% and 8 .97% +/- 1.60% at the concentration of 5.0, 10.0, 20.0 and 40.0 micromol/L CdCl(2) respectively, higher than those in the control group (6.69% +/- 0.46%) with the significant difference (P < 0.01). The CdCl(2) of between 10 and 40 micromol/L could highly induce the expression of HO-1 of the human embryonic kidney cells. The expression would increase slowly till the flat stage with the increase of the dosage and then would decrease slightly over time. CONCLUSION: The cadmium can induce the apoptosis of the human embryonic kidney cells and up-regulate the expression of HO-1.

Apoptosis↗
PubMed2006

[Expression, purification and immunogenicity of a novel hepatitis E virus-like particle].

AIM: To express and characterize a novel hepatitis E virus (HEV) recombinant protein which contains HEV neutralization epitope(s). METHODS: The gene fragment encoding for amino acid 452-617 of HEV open reading frame 2 protein (pORF2) was inserted into the plasmid pET28a(+). The recombinant plasmid was used to transform the E. coli BL21(DE3) strain. The recombinant protein was expressed by IPTG induction, purified by Ni-NTA chromatography and analyzed by SDS-PAGE, Western blot and electronmicroscopy. Immune responses to the recombinant protein were determined by the immunization of mice. RESULTS: The expressed HEV recombinant protein was in a naturally-soluble form with a molecular weight of 22,000. The protein assembled into a virus like particle (VLP) with a diameter of approximate 20 nanometers. Moreover, this novel protein was reactive to serum samples obtained from the patients with HEV infection. After the mice were immunized with the protein, they developed anti-HEV antibodies which could neutralize HEV infection in cell culture. CONCLUSION: An E. coli-expressed recombinant protein containing 166 amino acid of HEV pORF2 can form VLP with good immunogenicity and antigenicity. This novel HEV VLP is valuable for the development of HEV vaccine and new diagnostic kit.

Animals↗
PubMed2006

[Clinical observation and study of mechanisms of needle-picking therapy for primary infertility of abnormal sperm].

OBJECTIVE: To search for the best method for increasing clinical therapeutic effect on primary abnormality of sperm. METHODS: One hundred and sixty-eight cases of infertility were randomly divided into a treatment group of 85 cases and a control group of 83 cases. The treatment group were treated with needle-picking at bilateral Shengzhi points, Dicong Shenjing points and L2 Shenjing points as main. The control group were treated with oral administration of Wuzi Yanzong Pills [symbol: see text]. Their therapeutic effects were observed in 3 hospitals. RESULTS: The total effective rate of 83.5% and the pregnancy rate of the patient's wife of 78.8% in the treatment group, and corresponding figures were 54.2% and 43.4% in the control group, with a very significant difference between the two groups (P < 0.01); and reproductive hormones improved significantly after treatment in the two groups (P < 0.01); after treatment, superoxide dismulase (SOD) activity and Zn content in semen were elevated and cadmium level decreased significantly in the treatment group (P < 0.05). CONCLUSION: Needle picking therapy can significantly improve and regulate endocrine function, increase quality of semen and elevate pregnancy rate of the patient's wife for the patient of primary abnormal sperm.

Acupuncture Therapy↗
PubMed2005

Identification of core functional region of murine IL-4 using peptide phage display and molecular modeling.

Murine IL-4 is a pleiotropic cytokine with undefined core functional region for eliciting downstream signaling. We used molecular modeling to predict the binding sites recognized by an anti-IL-4-neutralizing mAb (11B.11) and peptide phage display to delineate their makeup. The results of these approaches were confirmed by site-directed mutagenesis analysis. The results suggest that the amino acid residues spanning from 79 to 86 (QRLFRAFR) on IL-4 are of the major binding site for 11B.11. Furthermore, the functional experiments demonstrate that the residues R80, R83 and R86, which are located in the helix C of murine IL-4, play a crucial role in binding to the IL-4R alpha-chain. Taken together, a new core functional region of murine IL-4 is identified, which provides new insight into the interaction between IL-4 and IL-4Ralpha. In addition, the results demonstrate that 11B.11 binds to a core functional region of murine IL-4, which prevents this cytokine from interacting with its cognate receptor.

Amino Acid Substitution↗
PubMed2005

A distinct lineage of CD4 T cells regulates tissue inflammation by producing interleukin 17.

Interleukin 17 (IL-17) has been linked to autoimmune diseases, although its regulation and function have remained unclear. Here we have evaluated in vitro and in vivo the requirements for the differentiation of naive CD4 T cells into effector T helper cells that produce IL-17. This process required the costimulatory molecules CD28 and ICOS but was independent of the cytokines and transcription factors required for T helper type 1 or type 2 differentiation. Furthermore, both IL-4 and interferon-gamma negatively regulated T helper cell production of IL-17 in the effector phase. In vivo, antibody to IL-17 inhibited chemokine expression in the brain during experimental autoimmune encephalomyelitis, whereas overexpression of IL-17 in lung epithelium caused chemokine production and leukocyte infiltration. Thus, IL-17 expression characterizes a unique T helper lineage that regulates tissue inflammation.

Animals↗
PubMed2005

Glycosylated recombinant human XCL1/lymphotactin exhibits enhanced biologic activity.

Chemokines are a family of small, secreted chemoattractant cytokines that regulate distribution and function of leukocytes during immune responses. While most chemokines are members of the CC or CXC subgroups, XCL1, also known as lymphotactin, is the sole member of the C subgroup. XCL1 is produced by activated CD8(+) T cells, NK cells, gammadelta T cells, and mast cells. XCL1 differs from other chemokines in that it contains only a single disulfide bond and a mucin-like domain at its carboxy terminus that is glycosylated. Understanding the biologic functions of chemokines has largely depended upon expression of these recombinant molecules in E. coli. To examine the effects of glycosylation on the biologic activity of XCL1, we designed constructs for expression of human XCL1 in insect S2 cells. Comparison of this material with that expressed in E. coli reveals that glycosylation significantly increases the biologic activity of XCL1.

Animals↗
PubMed2005

Hemolysis of erythrocytes by granulysin-derived peptides but not by granulysin.

Granulysin, a 9-kDa protein localized in human cytolytic T lymphocytes and natural killer cell granules, is cytolytic against tumors and microbes but not against red blood cells. Synthetic peptides corresponding to the central region of granulysin recapitulate the lytic activity of the intact molecule, and some peptides cause hemolysis of red blood cells. Peptides in which cysteine residues were replaced by serine maintain their activity against microbes but lose activity against human cells, suggesting their potential as antibiotics. Studies were undertaken to determine the mechanism of resistance of red blood cells to granulysin and sensitivity to a subset of granulysin-derived peptides. Granulysin lyses immature reticulocytes, which have mitochondria, but not red blood cells. Granulysin lyses U937 cells but not U937 cells lacking mitochondrial DNA and a functional respiratory chain (U937rho(o) degrees cells), further demonstrating the requirement of intact mitochondria for granulysin-mediated death. Peptide G8, which corresponds to helix 2/loop 2/helix 3, lyses red blood cells, while peptide G9, which is identical except that the cysteine residues were replaced by serine, does not lyse red blood cells. Granulysin peptide-induced hemolysis is markedly inhibited by an anion transporter inhibitor and by Na(+), K(+), and Ca(2+) channel blockers but not by Na(+)/K(+) pump, cotransport, or Cl(-) channel blockers. Although recombinant granulysin and G9 peptide do not induce hemolysis, they both competitively inhibit G8-induced hemolysis. The finding that some derivatives of granulysin are hemolytic may have important implications for the design of granulysin-based antimicrobial therapeutics.

Amino Acid Sequence↗
PubMed2005

[Study on the oxidative injury of the vascular endothelial cell affected by PM2.5].

OBJECTIVE: To study the mechanism of cardiovascular disease affected by PM2.5. METHODS: ECV304 cells were exposed to PM2.5 of different concentration (50, 200 and 400 microg/ml), after 24h, the viability of cells by MTT, SOD and GSH contents in cells and apoptosis of cells determined by flow cytometer were measured. RESULTS: Viability of ECV304 cells declined and mortality of ECV304 cells increased gradually with increase of concentration, GSH contents in cells (mg/g prot) were 20.643 +/- 2.167, 16.774 +/- 2.911 (P < 0.05), 15.658 +/- 3.471 (P < 0.01), and SOD contents in cells (U/mg prot) were 5.878 +/- 0.401, 5.140 +/- 0.448 (P < 0.01), 4.817 +/- 0.451 (P < 0.01) when the concentration of PM2.5 was 50, 200 and 400 microg/ml. CONCLUSION: PM2.5 can cause vascular endothelial cells to die by way of oxidative injury, then induce cardiovascular disease.

Air Pollutants↗
PubMed2005

MAP kinases in immune responses.

MAP kinases are evolutionarily conserved signaling regulators from budding yeast to mammals and play essential roles in both innate and adaptive immune responses. There are three main families of MAPKs in mammals. Each of them has its own activators, inactivators, substrates and scaffolds, which altogether form a fine signaling network in response to different extracellular or intracellular stimulation. In this review, we summarize recent advances in understanding of the regulation of MAP kinases and the roles of MAP kinases in innate and adaptive immune responses.

Animals↗
PubMed2004

A novel apoptosis pathway activated by the carboxyl terminus of p21.

Delivery of biologically active peptides into cells may help elucidate intracellular signal transduction pathways, identify additional in vivo functions, and develop new therapeutics. Although p21 was first identified as a major regulator of cell cycle progression, it is now clear that p21 subserves multiple functions. The amino terminus of p21 interacts with cyclins and cyclin-dependent kinases, while the carboxyl terminus interacts with proliferating cell nuclear antigen (PCNA), growth arrest and DNA damage-inducible gene 45 (GADD45), calmodulin, SET, and CCAAT/enhancer binding protein-alpha (C/EBP-alpha). A chimeric peptide, p21-IRS, consisting of the carboxyl terminal domain of p21 conjugated to a pentapeptide (RYIRS) rapidly enters lymphoid cells and activates apoptosis. In the present study, we investigate the molecular events involved in p21-activated apoptosis. Comparison of p21-IRS with other known proapoptotic agents demonstrates that p21-IRS activates a novel apoptotic pathway: mitochondria are central to the process, but caspases and a decrease in Deltapsi(m) are not involved. Targeting the p21 peptide to specific cell populations may allow development of novel therapies to eliminate aberrant cells in human diseases.

Amino Acid Sequence↗
PubMed2004

Protective effect of melatonin against liver injury in mice induced by Bacillus Calmette-Guerin plus lipopolysaccharide.

AIM: To investigate the effects and mechanisms of melatonin on immunological liver injury in mice. METHODS: A model of liver injury was induced by tail vein injection of Bacillus Calmette Guerin (BCG) and lipopolysaccharide (LPS) in mice. Kupffer cells and hepatocytes were isolated and cultured according to a modified two-step collagenase perfusion technique. Levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and nitric oxide (NO), content of malondiadehyde (MDA), activity of superoxide dismutase (SOD), were measured by biochemical methods. Tumor necrosis factor-alpha (TNF-alpha) activity was determined by RIA. Interleukin (IL)-1 activity was measured by thymocyte proliferation bioassay. Hepatic tissue sections were stained with hematoxylin and eosin and examined under a light microscope. RESULTS: Immunological liver injury induced by BCG+LPS was successfully duplicated. Serum transaminase (ALT, AST) activities were significantly decreased by melatonin (0.25, 1.0, 4.0 mg/kg bm). Meanwhile, MDA content was decreased and SOD in liver homogenates was upregulated. Furthermore, pro-inflammatory mediators (TNF-alpha, IL-1, NO) in serum and liver homogenates were significantly reduced by melatonin. Histological examination demonstrated that melatonin could attenuate the area and extent of necrosis, reduce the immigration of inflammatory cells. In in vitro experiment, TNF-alpha was inhibited at the concentrations of 10(-8)-10(-6) mol/L of melatonin, while IL-1 production of Kupffer cells induced by LPS (5 microg/mL) was decreased only at the concentration of 10(-6) mol/L of melatonin, but no effect on NO production was observed. Immunological liver injury model in vitro was established by incubating hepatocytes with BCG- and LPS-induced Kupffer cells. Activities of ALT, TNF-alpha, IL-1, and MDA in supernatant were significantly increased. Melatonin had little effect on the level of ALT, but reduced the content of TNF-alpha and MDA at concentrations of 10(-7)-10(-5) mol/L and decreased the content of IL-1 at concentrations of 10(-6)-10(-5) mol/L. CONCLUSION: Melatonin could significantly protect liver injury in mice, which was related to free radical scavenging, increased SOD activity and pro-inflammatory mediators.

Alanine Transaminase↗
PubMed2004

Murine B7-H3 is a negative regulator of T cells.

T cell activation is regulated by the innate immune system through positive and negative costimulatory molecules. B7-H3 is a novel B7-like molecule with a putative receptor on activated T cells. Human B7-H3 was first described as a positive costimulator, most potently inducing IFN-gamma production and cellular immunity. In this study we examined the expression and function of mouse B7-H3. B7-H3 is mostly expressed on professional APCs; its expression on dendritic cells appears to be up-regulated by LPS. In contrast to human B7-H3, we found that mouse B7-H3 protein inhibited T cell activation and effector cytokine production. An antagonistic mAb to B7-H3 enhanced T cell proliferation in vitro and led to exacerbated experimental autoimmune encephalomyelitis in vivo. Therefore, mouse B7-H3 serves as a negative regulator of T cell activation and function.

Animals↗
PubMed2004

Regulation of innate and adaptive immune responses by MAP kinase phosphatase 5.

Mitogen-activated protein (MAP) kinases are essential regulators in immune responses, and their activities are modulated by kinases and phosphatases. MAP kinase phosphatase (MKP) is a family of dual-specificity phosphatases whose function is evolutionarily conserved. A number of mammalian MKPs have been identified so far, but their specific physiological functions in negative regulation of MAP kinases have not been genetically defined. Here we examine innate and adaptive immune responses in the absence of MKP5. JNK activity was selectively increased in Mkp5 (also known as Dusp10)-deficient mouse cells. Mkp5-deficient cells produced greatly enhanced levels of pro-inflammatory cytokines during innate immune responses and exhibited greater T-cell activation than their wild-type counterparts. However, Mkp5-deficient T cells proliferated poorly upon activation, which resulted in increased resistance to experimental autoimmune encephalomyelitis. By contrast, Mkp5-deficient CD4(+) and CD8(+) effector T cells produced significantly increased levels of cytokines compared with wild-type cells, which led to much more robust and rapidly fatal immune responses to secondary infection with lymphocytic choriomeningitis virus. Therefore, MKP5 has a principal function in both innate and adaptive immune responses, and represents a novel target for therapeutic intervention of immune diseases.

Animals↗
PubMed2004

ICOS is essential for the development of experimental autoimmune myasthenia gravis.

Lymphocyte costimulation via the inducible costimulatory molecule (ICOS) is required for effective humoral immunity development. Following immunization with Torpedo acetylcholine receptor (AChR), ICOS gene knockout (KO) mice were highly resistant to clinical experimental autoimmune myasthenia gravis (EAMG) development, had less serum AChR-specific immunoglobulins (Igs), and exhibited a diminutive germinal center (GC) reaction in secondary lymphoid tissues. Lymphocyte proliferation and both Th1 and Th2 differentiation in response to AChR and the AChR dominant alpha146-162 peptide were inhibited by the ICOS gene deficiency. ICOS-mediated lymphocyte costimulation is thus vital to the induction of T cell-mediated humoral immunity to AChR and the development of clinical EAMG.

Animals↗
PubMed2004

[Occupational exposure profiles of polycyclic aromatic hydrocarbons in coke oven workers].

OBJECTIVE: To study the characteristics of occupational exposure of polycyclic aromatic hydrocarbons (PAHs) in coke oven workers. METHODS: Samples were collected individually and PAHs concentration in the ambient air were assayed by high performance liquid chromatography (HPLC) and toxic equivalency factors (TEFs) were introduced to assess the carcinogenic potency. RESULTS: The levels of PAHs occupational exposure in oven workers at topside was higher than at side oven and bottom oven (P < 0.05). Non-carcinogenic PAHs were more than 70% of total PAHs and benzo[a]pyrene accounted for 65.5% approximately 72.4% of total benzo[a]pyrene equivalents. Total occupational exposure level of PAHs in coke oven workers was positively related to the content of benzo[a]pyrene and pyrene, respectively (r(2) = 0.84, r(2) = 0.94, P < 0.05). CONCLUSION: Coke oven workers were exposed to a high level of PAHs which possessed some extent of carcinogenic potency, and benzo[a]pyrene is the chief carcinogenic substance.

Benzo(a)pyrene↗
PubMed2003

A critical role of neural-specific JNK3 for ischemic apoptosis.

c-Jun N-terminal kinase (JNK) signaling is an important contributor to stress-induced apoptosis, but it is unclear whether JNK and its isoforms (JNK1, JNK2, and JNK3) have distinct roles in cerebral ischemia. Here we show that JNK1 is the major isoform responsible for the high level of basal JNK activity in the brain. In contrast, targeted deletion of Jnk3 not only reduces the stress-induced JNK activity, but also protects mice from brain injury after cerebral ischemia-hypoxia. The downstream mechanism of JNK3-mediated apoptosis may include the induction of Bim and Fas and the mitochondrial release of cytochrome c. These results suggest that JNK3 is a potential target for neuroprotection therapies in stroke.

Animals↗