Biomedical subjects

Xiang Xu

Publications and source records attributed to Xiang Xu.

29 records · Page 2Linked to original sources

PubMed2003

[An experimental study of inhibiting effect of decoy oligodeoxynucleotides on the gene expression of collagen in NIH3T3 cell].

OBJECTIVE: To investigate the effect of activator protein-1 (AP-1) decoy-oligodeoxynucleotides (Decoy-ODNs) on the expression of fibroblast alpha2 type I collagen, so as to explore the gene therapy of pathologic scar. METHODS: Decoy-ODNs targeting AP-1 were designed and synthesized. NIH3T3 cells were transfected by cationic liposomes. The distribution of Decoy-ODNs in the cells was investigated. The inhibiting effects of Decoy-ODNs on AP-1 were determined by electrophoretic mobility shift assay (EMSA). And the effects of Decoy-ODNs on the collagen synthesis in the cells were analyzed by RT-PCR. RESULTS: AP-1 Decoy-ODNs could competitively inhibit the AP-1 in vitro activity. Cationic liposomes could play roles by effectively transfecting Decoy-ODNs into the plasma and nucleus. The mRNA expression of fibroblast alpha2 type I collagen decreased evidently after 24 hours of Decoy-ODNs action. CONCLUSION: Decoy-ODNs could inhibit the mRNA expression of fibroblast alpha2 type I collagen by antagonizing AP-1.

Animals↗

PubMed2003

Effect of decoy-oligodeoxynucleotides on expression of inflammation mediators in pMPhi cells from rats.

OBJECTIVE: To study the effect of decoy-oligodeoxynucleotides (decoy-ODNs) in dumbbell shape with the oligodeoxynucleotide sequence similar to nuclear factor kappa B (NF-kappaB) cis-elements on expression of inflammation mediators in pMPhi cells from rats. METHODS: With carriers of cationic liposomes, decoy-ODNs were transfected into pMPhi cells of rats. Then the inhibiting effects of the decoy-ODNs on tumor necrosis factor alpha (TNFalpha), interleukin-6 (IL-6) and IL-10 were analyzed. RESULTS: Decoy-ODNs could decrease the expression of TNFalpha and IL-6 in dose-dependent fashion but had weaker inhibiting effect on IL-10. CONCLUSIONS: Decoy-ODNs targeting NF-kappaB can decrease the expression of inflammatory mediators in pMPhi cells from rats.

Animals↗

PubMed2003

[Progress in locked nucleic acid research].

Locked nucleic acid (LNA) is a novel oligonucleotide analogue in which 2'-O and 4'-C positions in the b-D-ribofuranosyl ring are joined via an O-methylene, S-methylene or amino-methylene moiety, locked in a C3'-endol3E north (N)-type furanose conformation. LNAs posses many properties, such as extraordinarily high hybridize affinities for complementary DNA/RNA sequences, remarkable antisense activity, nuclease resistance, good aqueous solubility and none detactable toxicity, et al. LNAs is a most promising molecule for development of diagnostics and therapeutics. For example, apply LNAs to single--nucleotide polymorphisms genotyping, telomerase activity have been efficiently suppressed by LNA oligomers, efficient cleavage of highly structured RNA has been achieved using LNA-modified DNAzymes (LNAzymes), and so on.

Animals↗

PubMed2003

[Construction,identification and amplification of a yeast two-hybrid random cycle peptide library].

AIM: To construct a cycle peptide library composed of 16 random amino acids with yeast two-hybrid system. METHODS: Random oligonucleotides encoding 16-mer peptides were designed and synthesized artificially, and then were amplified by PCR. The amplified products were digested with BamH I and EcoR I and cloned into yeast expression plasmid pGADT(7) GH to construct the cycle library plasmids pGADT(7) GH-RP Then the number of different recombinants and the randomness of the library were tested, and the cycle peptide library plasmids were amplified, extracted and purified. RESULTS: A random cycle peptide library with 1.28 x10(7) different recombinant clones was obtained. No significant difference was found between amino acid distribution in the cycle peptide library and the expected frequency. CONCLUSION: The random cycle peptide library has been successfully constructed. And a lot of cycle peptide library plasmids with high purity were obtained.

Amino Acid Sequence↗

PubMed2002

Mast cell dynamics and involvement in the development of peritoneal adhesions in the rat.

Mast cells have been implicated in the ethiopathology of post-operative peritoneal adhesions. However an evaluation of their role in this condition is missing. Adhesions were induced in rats using small intestinal scraping. These rats or rats injected ip with either Stem Cell Factor (SCF) or nedocromil sodium or compound 48/80 (day 0-20) were sacrificed for grading of peritoneal adhesions, for evaluating mast cells and inflammatory cells in adhesions and peritoneal lavage (histochemical staining) and for histamine content (peritoneal lavage, radioenzymatic assay) on days 1-21. Mast cell sonicate was added to intestinal fibroblast and their proliferation was assessed (cell counting). All the rats developed adhesions (day 1) and after 3 days the adhesion score remained constant. Early adhesions were avascular and made of fibrinous exudate containing many mast cells. Thereafter adhesions became denser, and the number of stainable mast cells decreased and then stabilized. On the first few days, inflammatory cells in the peritoneal lavage increased while mast cells and histamine content were significantly reduced indicating their activation. Injection of SCF for 1 week slightly increased peritoneal adhesion formation while nedocromil sodium reduced their development. Compound 48/80 had no significant influence. Addition of mast cell sonicate to normal intestine or to peritoneal adhesion fibroblasts resulted in a significant increase of fibroblast proliferation. In conclusion, mast cell presence correlated with the establishment of peritoneal adhesions, and their pharmacological modulation influenced adhesion formation. In vitro mast cell induced fibroplasia. Therefore, mast cells have a profibrogenic role in this model of peritoneal adhesions.

Animals↗

PubMed2002

Mast cells involvement in the inflammation and fibrosis development of the TNBS-induced rat model of colitis.

BACKGROUND: Mast cells have been implicated in chronic inflammatory conditions resulting in fibrosis, such as Crohn disease. However, a link between inflammation, fibrosis and mast cells has not been demonstrated in human or animal intestinal diseases. This work was undertaken to analyze whether mast cells play a role in inflammation and fibrosis in the TNBS-induced rat colitis. METHODS: Rats were rectally instilled 2,4,6,-trinitrobenzene sulfonic acid in ethanol, and immediately or 4 days later injected daily i.p. with nedocromil sodium, a mast cell stabilizer, compound 48/80, a mast cell activator, or saline. Rats were sacrificed 5 days post-TNBS, or on day 21. Intestinal inflammation and fibrosis were assessed by gross and histopathological evaluation. Colonic mast cell numbers (toluidine blue) and collagen (type I mRNA expression) were evaluated. Mast cell sonicate was added to rat colon fibroblasts. Fibroblast proliferation (3H-thymidine), collagen synthesis (3H-proline) and contractile activity (tridimensional collagen lattice contraction) were then assessed. RESULTS: Nedocromil reduced inflammation and fibrosis possibly by decreasing mast cell numbers and activation and consequent collagen production. Compound 48/80 slightly enhanced the severity of the disease by activating mast cells. Mast cells increased fibroblast proliferation, collagen production and contractile activity. CONCLUSIONS: Mast cells are involved in the gastrointestinal tract inflammation and fibrosis of the TNBS-colitis rats.

Animals↗

PubMed2002

Role of mast cells and myofibroblasts in human peritoneal adhesion formation.

OBJECTIVE: To study fibroblasts and mast cells in human peritoneal adhesions and to evaluate whether their interaction plays a role in adhesion development. SUMMARY BACKGROUND DATA: Myofibroblasts play a critical role in wound repair/fibrosis. Mast cells influence the formation of peritoneal adhesions in a rat model, and they are modulators of fibroblast functions. METHODS: Peritoneal adhesion biopsies were processed for either histology (H&E, toluidine blue) or immunohistochemistry (tryptase, laminin, collagen type IV and VIII, and alpha-SMA) or grown as explants for obtention of fibroblasts. The effects of mast cell (HMC-1) sonicate and selected mast cell mediators and cytokines on fibroblast proliferation ([ (3)H]thymidine) and collagen synthesis ([ (3)H]proline) and on fibroblast contractile activity (tridimensional collagen lattice) were evaluated. Mast cell mediators influencing fibroblast proliferation were partially characterized by enzymatic susceptibility and FPLC gel filtration column chromatography. RESULTS: Most of the fibroblasts in peritoneal adhesions were identified as alpha-SMA-positive myofibroblasts. Mast cell hyperplasia was observed and more than one third of the mast cells were degranulated. Few mast cells showed a faint staining for laminin or collagen type IV and VIII. Mast cell sonicate increased fibroblast proliferation and contractile activity while decreasing collagen synthesis. Mast cell sonicate proliferating activities were found to be proteinase-sensitive with a molecular weight of more than 158 kd, of approximately 40 kd, and of less than 10 kd. TGF-beta and tryptase enhanced collagen synthesis; TNF-alpha and chymase decreased it. None of the selected mediators increased fibroblast proliferation. CONCLUSIONS: Myofibroblasts are the main connective tissue cells present in human peritoneal adhesions, and mast cells play a direct role in peritoneal adhesion formation.

Cell Division↗

PubMed2002

Relations of transcription expression of IL-2 with nuclear factor of activated T cells as well as changes of C-Fos and C-Jun after trauma.

OBJECTIVE: To observe the relations among expression of interleukin-2 (IL-2) in spleen lymphocytes, DNA binding activity of nuclear factor of activated T cells (NFAT) and expression of the partly family members C-Fos, C-Jun after trauma. METHODS: A murine closed trauma model was used, animals were sacrificed 6, 12 hours and 1, 4, 7, 10, 14 days, respectively after injury. Spleen lymphocytes were isolated from injured mice and stimulated with concanavalin-A. The culture supernatants were harvested and assayed for IL-2 activity. Total RNA was extracted from spleen lymphocytes and assayed for IL-2 mRNA. Nuclear protein was extracted, and the DNA binding activity of NFAT was measured using an electrophoretic mobility shift assay (EMSA), the expressions of C-Fos, C-Jun protein determined by Western blot analysis. RESULTS: The expressions of IL-2 activity and IL-2 mRNA in spleen lymphocytes were decreased in injured mice compared with those in control mice, and the most obvious decrease appeared on the 4th day after injury. The DNA binding activity of NFAT decreased gradually and reached the minimum that was only 41% of the control on the 4th day after injury, which was closely associated with the decline of IL-2 activity and IL-2 mRNA. An decrease in the expression of C-Fos on the 1st and 4th day after injury, trauma had no significant effect on the C-Jun expression. CONCLUSIONS: These results suggest that the inhibition of IL-2 expression is partly due to the impairment in the activation of NFAT in injured mice; and the decline in the DNA binding activity of NFAT is partly due to trauma block in the C-Fos expression.

Animals↗

PubMed2002

Decline in the expression of IL-2 after trauma and changes in the nuclear transcription factors NFAT and AP-1.

OBJECTIVE: To investigate whether the decrease in expression of interleukin-2 (IL-2) after trauma is associated with changes in DNA binding activity of nuclear factor of activated T cells (NFAT) and activator protein-1 (AP-1). METHODS: Mice with closed impact injury with fracture in both hind limbs were adopted as the trauma model. Spleen lymphocytes were isolated from traumatized mice and stimulated with Con-A. Culture supernatants were assayed for IL-2 activity, and total RNA was extracted from spleen lymphocytes and assayed for IL-2 mRNA. DNA binding activity of NFAT and AP-1 were measured by electrophoretic mobility shift assay (EMSA). The expression of c-Fos, c-Jun and JunB proteins was determined by the Western blot analysis. RESULTS: DNA binding activity of NFAT and AP-1 gradually decreased to a minimum of 41% and 49%, respectively, of the control on the 4th day after injury, which was closely followed by the decline in IL-2 activity and IL-2 mRNA. A decrease in the expression of c-Fos on the 1st and 4th day after trauma had no significant effect on c-Jun expression; the increase in expression of JunB was only on the 1st day after injury. CONCLUSION: Decreased IL-2 expression is, at least in part, due to a decline in the activation of NFAT and AP-1 in traumatized mice. The decline in DNA binding activity of NFAT and AP-1 is partly due to a trauma-induced block in the expression of c-Fos.

Animals↗

PubMed2000

The effect of macrophages posttrauma on T cell functions.

OBJECTIVE: To study molecular mechanism of suppressive effect of macrophages posttrauma on T cell functions. METHODS: A murine closed trauma model was used, macrophages were harvested from the abdominal cavity and added into the culture system of T cells, which were separated from splenocytes in normal mice using nylon column. T cell functions and intracellular messenger molecules were determined. In addition, the effect of macrophages' removal from splenocytes of traumatized mice on T cell functions and intracellular messenger molecules was investigated. RESULTS: Macrophages posttrauma in vitro could obviously suppress ConA stimulated normal T cell functions such as T lymphocyte transformation, interleukin 2 (IL-2) production, IL-2 receptor alpha (IL-2Ralpha) expression, IL-2 mRNA and IL-2Ralpha mRNA levels, and elevate cAMP contents of activated normal T cells while decreasing cGMP contents, intracellular free calcium ([Ca(2+)]i) concentration and protein kinase C (PKC) activity. Removal of macrophages from splenocytes of traumatized mice could at certain degree reverse the suppression of T cell functions, decrease cAMP contents while increasing cGMP contents, [Ca(2+)]i concentration and PKC activity. CONCLUSIONS: Macrophages posttrauma may suppress T cell functions via altering messenger molecule levels in activated T cells.

Journal Article↗

PubMed1998

Inhibition of T cells by direct contact with macrophages after murine-amputation injury.

OBJECTIVE: To determine whether macrophages post trauma have inhibitory effect on normal T cells via direct cell to cell contact. METHODS: A murine amputation injury model was used, macrophages were harvested from abdominal cavity and treated with mitomycin-C to abrogate the secretion of cytokines. Separation of T cells from splenocytes in normal mice was performed using nylon column method. Mitomycin-C treated macrophages from control and traumatized mice were added into the normal T cell culture systems, then various parameters of T cell functions were determined. RESULTS: The production and secretion of interleukin 1 (IL-1), interleukin 6 (IL-6), tumor necrosis factor (TNF) and prostaglandin E-2 (PGE-2) could be abrogated after macrophages were treated with 25 &mgr;g/mL mitomycin-C for 30 minutes. Mitomycin-C treated macrophages from traumatized mice could obviously suppress T lymphocyte transformation, IL-2 mRNA and IL-2Ralpha mRNA levels, IL-2 production, IL-2Ralpha expression, IL-2 mediated lymphocyte proliferation response of normal T cells, could not affect IL-2-IL-2R interaction but elevated suppressive action of Ts cells. Removal of Ts cells from T cells could almost abolish the inhibition of macrophages. CONCLUSIONS: Macrophages post trauma can suppress T cell functions by depressing IL-2 and IL-2Ralpha gene expression via direct cell to cell contact, and this effect may be mediated mainly by increasing the action of Ts cells.

Journal Article↗