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Hui Xu

Publications and source records attributed to Hui Xu.

At least 145 records · Page 8Linked to original sources
PubMed2003

Partial filling technique in capillary electrophoresis for the separation of phenolic isomers with sulfonatocalix[4]arene as a selector.

p-Sulfonatocalix[4]arene was used as a selector in capillary electrophoresis to separate phenolic positional isomers. To avoid the detection interference caused by the high UV absorption of calixarene, the partial filling technique was applied. The operation variables, including buffer, separation voltage, the concentration of the selector and the plug length of the selector zone, were systematically optimized. The detection limits of mass were in the range of 0.07-0.28 pg. Molecular modeling was used to explain the interaction between calixarene and phenolic isomers.

Electrophoresis, Capillary↗
PubMed2003

Superconducting RF coils for clinical MR imaging at low field.

RATIONALE AND OBJECTIVES: A number of recent reports in the MRI literature have established that substantial signal-to-noise ratio (SNR) gains can be achieved with small samples or low resonance frequencies, through the use of high-quality factor high-temperature superconducting (HTS) RF receive coils. We show the application of HTS coils to the imaging of human subjects with improved SNR compared with copper coils. MATERIALS AND METHODS: HTS coils were constructed from 7.62-cm YBa2Cur3O7-delta thin films on LaAlO3 substrate and cooled in a liquid nitrogen cryostat. Human and phantom images were acquired on a 0.2-T scanner. The SNR improvements compared with equivalent-sized copper coils are reported. RESULTS: SNR gains of 2.8-fold and 1.4-fold were observed in images of a phantom acquired with an HTS coil versus a room temperature copper coil and a liquid nitrogen-cooled copper coil, respectively. Preliminary results suggest higher image quality can be obtained in vivo with an HTS coil compared with copper coil imaging. Images of human orbit, brain, temporomandibular joint, and wrist are presented. CONCLUSION: The experimental results show that benefits can be expected from application of HTS surface coils in human MR imaging with low-field scanners. These potential benefits justify the continued development of practical HTS coil imaging systems despite the considerable technical difficulties involved in cryostat and coil design.

Brain↗
PubMed2003

Helper-Independent Sleeping Beauty transposon-transposase vectors for efficient nonviral gene delivery and persistent gene expression in vivo.

Transposon-based vectors represent promising new tools for chromosomal transgene insertion and establishment of persistent gene expression in vivo. Here, we report the development of helper-independent transposon-transposase (HITT) vectors, which contain on single plasmids (i) a Sleeping Beauty (SB) transposon containing the transgene and (ii) a SB transposase expression cassette. To obtain an optimal level of transposase expression from HITT vectors, we determined the relative strength of a panel of different promoters in mouse liver and used these promoters to drive transposase expression from injected HITT vectors carrying a human alpha(1)-antitrypsin (hAAT) expression cassette flanked by transposon inverted repeats. By correlating promoter strength with stabilized serum hAAT levels, a narrow expression window supporting high-level transposition in the liver was defined. Peak levels of long-term gene expression were obtained with promoters 30- to 40-fold less active than CMV in mouse liver, whereas reduced stable levels of hAAT were detected with both weaker and stronger promoters. Injected HITT vectors induced transposase-dependent insertion of transposon DNA into the genome of at least 5-6% of transfected hepatocytes, generating levels of persistent hAAT expression that were 2- to 4-fold higher than with an optimized two-plasmid approach. In addition, we show that HITT vectors carrying a human factor IX (hFIX)-containing transposon support (i) long-term hFIX expression in normal mice and (ii) partial phenotypic correction in a mouse model of hemophilia B. SB-based HITT vectors represent a major advance in the establishment of persistent transgene expression from nonviral gene delivery systems and should prove useful for gene transfer to tissues or cell types in which transfection efficiencies are low.

Animals↗
PubMed2003

Experimental sinus grafting with the use of deproteinized bone particles of different sizes.

This study compared the osteoconductive capability of deproteinized bone particles of two different sizes (300-500 and 850-1000 microm) in rabbits undergoing maxillary sinus lift. Histologically, deproteinized bone particles of both sizes induced osteoconduction 1 week after implantation. Bone initially formed at the sinus wall and proliferated into the center of the augmented sinus cavity. In the small-particle group, newly formed bone showed many interconnections and appeared in most areas of the cavity 8 weeks after implantation. In the large-particle group, newly formed bone showed limited intercommunications, and the center of the sinus cavity contained fibrous connective tissue with no evidence of ossification 8 weeks after implantation. Histomorphometric analysis revealed a significantly higher density of newly formed bone in the small-particle group than in the large-particle group both 4 and 8 weeks after implantation. The total newly formed bone-particle contact length was also significantly higher in the small-particle group. The total surface length of the small particles was larger than that of the large particles, but the ratio of the newly formed bone-particle contact length to the total particle surface length did not differ significantly between the groups at any time. The interparticular spaces of the small particles were larger than those of the large particles. The bone area ratio in the interparticular spaces of the small particles was significantly higher than that of the large particles both 4 and 8 weeks after implantation. We conclude that graft bone particle size and interparticular space are important determinants of osteoconduction.

Analysis of Variance↗
PubMed2003

Pleomorphic adenoma of the submandibular salivary glands with marked ossification.

This article describes an unusual case of pleomorphic adenoma arising in the submandibular salivary glands that was associated with marked ossification. CT scan showed an irregular high-density mass in the left submandibular region. Histologic examination of the resected mass revealed a well-circumscribed pleomorphic adenoma with chondroid tissue intermingled with glandular and trabecular epithelial components. Irregularly formed osseous tissue was present in the chondroid tissue. The osseous tissue showed bone matrix on von Kossa's staining. Alkaline phosphatase expression was restricted to the vicinity of osseous tissue. Tartrate-resistant acid phosphatase-positive osteoclasts were observed at the periphery of the osseous tissue. CD34 staining demonstrated many microvascular vessels in both the chondroid and osseous tissues. We conclude the osseous tissue in pleomorphic adenoma was bone in nature, and via the process of endochondral ossification most likely depended on angiogenesis.

Acid Phosphatase↗
PubMed2003

Mite allergen induces allergic dermatitis with concomitant neurogenic inflammation in mouse.

Pathogenesis of atopic dermatitis involved the interactions of immune and neuroendocrine systems. Here we describe a mouse model for atopic dermatitis with concomitant neurogenic inflammation, by epicutaneous sensitization with a dust mite allergen. Allergen patching resulted in localized dermatitis characterized by pronounced epidermal hyperplasia and spongiosis, which was associated with infiltration of eosinophils and neutrophils, degranulated mast cells, CD4+ and CD8+ T cells, and dendritic cells. There was increased innervation of calcium gene related peptides and substance P in inflamed skins, interactions between nerve fibers and mast cells were seen, indicating the coexistence of neurogenic inflammation. Splenic T cells produced T helper 2-polarized cytokines in response to allergen stimulation in vitro, indicating systemic allergen sensitization. This is the first report of a mouse model of eczema, accompanied by neurogenic inflammation, which shows close resemblance to human allergic diseases. This work supports the notion that the skin is an important site for the initiation of primary allergen sensitization. Besides, this model may also be useful for study of other stress-associated neuroinflammatory skin disorders such as neurogenic pruritus and psoriasis.

Administration, Cutaneous↗
PubMed2003

CloN2, a novel acyltransferase involved in the attachment of the pyrrole-2-carboxyl moiety to the deoxysugar of clorobiocin.

The aminocoumarin antibiotic clorobiocin contains a 5-methylpyrrole-2-carboxylic acid unit, attached via an ester bond to the 3-OH group of the deoxysugar moiety. To investigate candidate genes responsible for the formation of this ester bond, a gene inactivation experiment was carried out in the clorobiocin producer Streptomyces roseochromogenes var. oscitans DS 12.976. An in-frame deletion was created in the coding sequence of the gene cloN2. The production of secondary metabolites in the wild-type and in the cloN2 mutant was analysed. The wild-type showed clorobiocin as the main product, whereas the cloN2 mutant accumulated a new aminocoumarin derivative, novclobiocin 104, lacking the pyrrole moiety at the 3-OH of the deoxysugar. In addition, free pyrrole-2-carboxylic acid accumulated in the culture extract of the cloN2 mutant. The structures of the metabolites were confirmed by NMR and LC-MS analysis. Clorobiocin production was successfully restored in the cloN2 mutant by introducing a replicative plasmid containing the cloN2 sequence. These results prove an involvement of cloN2 in the formation of the ester bond between the pyrrole moiety and the deoxysugar in clorobiocin biosynthesis. Furthermore, they indicate that the C-methylation at position 5 of the pyrrole moiety occurs after the attachment of pyrrole-2-carboxylic acid unit to the deoxysugar moiety.

Acyltransferases↗
PubMed2003

Episomal persistence of recombinant adenoviral vector genomes during the cell cycle in vivo.

Previously we showed that recombinant adenoviral helper-dependent (HD) vectors result in long-term transgene expression levels in vivo which slowly declined by 95% over a period of 1 year. In this study, we further establish that this was not predominantly immune mediated. To determine if cell turnover was responsible for the loss of transgene expression, we induced rapid hepatocyte cell cycling in mouse liver, by performing a surgical two-thirds partial hepatectomy. We observed a 55 and 65% reduction in transgene expression levels and a 50 and 71% loss of vector genomes for the HD vector and the first-generation adenoviral vector. In sharp contrast, in nonviral, episomal plasmid DNA-injected mice, transgene expression levels and DNA copy numbers decreased by 95 and 99%, respectively. These findings suggest that cell division alone was not the primary reason for the slow decrease in transgene expression levels and that recombinant adenoviral vectors have a more robust mechanism for maintaining persistence during cell cycling. Several potential mechanisms are proposed.

Adenoviridae↗
PubMed2003

Tgf-beta inhibits activation and uveitogenicity of primary but not of fully polarized retinal antigen-specific memory-effector T cells.

PURPOSE: TGF-beta exerts suppressive effects on immunity, but its potential applications in therapy of ocular autoimmunity have not been widely explored. In the present study, the effects of TGF-beta on uveitogenic T cells were examined. METHODS: The effects of TGF-beta on newly primed cells from mice given a uveitogenic regimen of interphotoreceptor retinoid-binding protein (IRBP) were compared with the effects on fully polarized Th1 cells from a long-term uveitogenic T-cell line. The parameters measured were T-cell proliferation, IFN-gamma production, induction of IL-12R expression, triggering of pathogenicity, and expression of costimulatory molecules on antigen-presenting cells (APCs) during in vitro exposure to antigen. RESULTS: TGF-beta suppressed B7.1 expression on APCs in cultures of lymph node cells from immunized mice. It also suppressed T-cell proliferation, IFN-gamma production, IL-12 receptor accumulation, and the IL-12-promoted acquisition of uveitogenic function. In contrast, the polarized Th1 cells were either resistant to suppression or were enhanced by TGF-beta. CONCLUSIONS: The results suggest that TGF-beta suppresses acquisition of effector functions by autopathogenic T cells, in part by interfering with their response to IL-12 through downregulation of IL-12R expression and in part through inhibition of APC function. The data suggest that although TGF-beta may effectively inhibit activation and recruitment of new T cells into the effector pool, it may be less effective in suppressing the reactivation of already polarized memory T cells that are less dependent on IL-12 and costimulation.

Animals↗
PubMed2003

Effect of compound rhodiola sachalinensis A Bor on CCl4-induced liver fibrosis in rats and its probable molecular mechanisms.

AIM: To explore the anti-fibrotic effect of a traditional Chinese medicine, compound rhodiola sachalinensis A Bor on CCl(4)-induced liver fibrosis in rats and its probable molecular mechanisms. METHODS: Ninety healthy male SD rats were randomly divided into three groups: normal group (n=10), treatment group of compound rhodiola sachalinensis A Bor (n=40) and CCl(4)-induced model group (n=40). The liver fibrosis was induced by CCl(4) subcutaneous injection. Treatment group was administered with compound rhodiola sachalinensis A Bor (0.5 g/kg) once a day at the same time. Then the activities of several serum fibrosis-associated enzymes: alanine aminotransferase (ALT), aspartate aminotransferase (AST), N-acetyl-beta-D-glucosaminidase (beta-NAG) and the levels of serum procollagen III (PCIII), collagen IV (CIV), hyaluronic acid (HA) were assayed. The histopathological changes were observed with HE, VG and Masson stain. The expression of TGF-beta1 mRNA, alpha1 (I) mRNA and Na(+)/Ca(2+) exchanger (NCX) mRNA was detected by reverse transcription polymerase chain reaction (RT-PCR) in situ. RESULTS: Compound rhodiola sachalinensis A Bor significantly reduced serum activities of ALT, AST, beta-NAG and decreased the levels of PCIII, CIV, HA, improved the liver histopathological changes, inhibited the expression of TGF-beta1 mRNA, alpha (I) mRNA and Na(+)/Ca(2+) exchanger mRNA in rats. CONCLUSION: Compound rhodiola sachalinensis A Bor can intervene in CCl(4)-induced liver fibrosis in rats, in which potential mechanisms may be decreasing the production of TGF-beta1, reducing the production of collagen, preventing the activation of hepatic stellate cell (HSC) and inhibiting the expression of TGF-beta1 mRNA, alpha1(I) mRNA and Na(+)/Ca(2+) exchanger mRNA.

Animals↗
PubMed2003

Difference in responsiveness of human esophageal squamous cell carcinoma lines to epidermal growth factor for MMP-7 expression.

Expression of MMP-7 in human esophageal squamous cell carcinoma lines (TE-9 and -10) was investigated. Under normal culture conditions, immunocytochemical staining and enzymography demonstrated the production of MMP-7 in their cytoplasm and its gelatinolytic activity in the medium of TE-9 and -10 cell cultures. When EGF was added to the cultures, Western blotting and RT-PCR analysis showed a dose-dependent increase in the amount of MMP-7 synthesized in the TE-9 cells, whereas in TE-10 cells, EGF failed to stimulate MMP-7 production. For luciferase reporter analysis of MMP-7 transcription, pMMP7LucWI (1132-bp) and pMMP7LucWII (334-bp) were cloned in the luciferase pGL3-basic vector. The promoter activity was enhanced from 1.5- to 2-fold by the addition of EGF to TE-9 cells transfected with pMMP7LucWI or WII, even though the response was low as compared with that of 12-O-tetra-decanoyl-phorbol-13-acetate (TPA); and in TE-10 cells, only TPA enhanced the promoter activity of MMP-7. Luciferase promoter analysis using a pMMP7WII mutant series revealed that the AP-1 site was essential for transcription of the MMP-7 gene in TE-9 cells, and Tcf-I was also an important site, and that to a lesser degree, Tcf-II and PEA3s participated in the transcription of the MMP-7 gene in these cells. Unlike the results with TE-9 cells, in TE-10 cells, EGF failed to stimulate transcription of the MMP-7 gene; and up-regulation of the promoter activity by TPA was dependent on the AP-1 site and to lesser degree, on Tcf-I and Tcf-II. These results suggest that EGF plays also an important role in MMP-7 production of TE-9 cells and that there is a difference not only in EGF-intracellular signaling system but also in regulation mechanisms of MMP-7 transcription by beta-catenin-Tcf and/or PEA3 system between these 2 carcinoma lines.

Carcinogens↗
PubMed2003

[Enhancement of gastrointestinal absorption of chitosan-coated insulin-loaded poly (lactic-co-glycolic acid) nanoparticles].

AIM: To study chitosan-coated poly (lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) on enhancing gastrointestinal absorption of insulin. METHODS: Insulin-loaded PLGA multiple emulsions were prepared by a double-emulsion method. Using chitosan as a stabilizer, chitosan-coated PLGA-NPs was prepared. The changes of the morphology, size distribution and Zeta potential of the NPs were examined. The encapsulation efficiency was determined by HPLC. The release behaviors in vitro were assessed, and the hypoglycemic effects were evaluated by monitoring the glucose levels in diabetic rats. RESULTS: Chitosan-coated PLGA-NPs showed a narrow size of distribution and regular surface with layer structure and their Zeta potential can be changed by chitosan. Chitosan-coating increased the encapsulation efficiency of insulin, reduced the initial burst and improved the release behavior of the NPs. About 14-16 h after intragastric administration of chitosan-coated INS-PLGA-NPs, the plasma glucose level decreased significantly compared with intragastric administration of same dose of non-coated NPs (P < or = 0.05), and the relative pharmacological availability was increased up to (15.4 +/- 1.2)%. CONCLUSION: Chitosan-coated PLGA-NPs could enhance gastrointestinal absorption of insulin.

Animals↗
PubMed2003

[The contribution of maize and soybean to N2O emission from the soil-plant system during seedling stage].

To fractionate the contribution of plant to N2O emission from soil-plant system, the N2O emissions from soybean seedling, maize seedling, sand, soil, sand-plant system and soil-plant system were measured by closed chamber method in greenhouse. At the same time the correlation of plant N2O emission with nitrate reductase activity, nitrate content and nitrite content of the plant leaves was also analyzed. The results clearly indicated that N2O could be a by-product of plant metabolism. The emissions of N2O from maize and soybean accounted for 93%-100% of the total N2O emissions in the sand-plant systems, and 79.18%-92% in the soil-plant systems. The flux of plant N2O emission was significantly correlated (R2 > or = 0.97, n = 6) with the nitrate reductase activities, nitrate content and nitrite content of the maize and soybean leaves.

Nitrate Reductase↗
PubMed2003

[Oxygen-limited autotrophic nitrification and denitrification--a novel technology for biological nitrogen removal].

Oxygen-limited autotrophic nitrification and denitrification (OLAND) is a biological nitrogen removal process coupled with partial nitrification and anaerobic ammonium oxidation. In our study, the nitrification was blocked at nitrite stage by controlling the dissolved oxygen concentration at 0.1-0.3 mg.L-1, and then, the denitrification proceeded, with the residual ammonium at the partial nitrification stage as electron donor. As a completely autotrophic nitrification-denitrification process, the OLAND was of many advantages (e.g., low energy consumption, high nitrogen removal rate and small footprint of system), and suitable in particular for treating low COD/NH4(+)-N ratio wastewater. It has become one of the most prosperous and practicable biological nitrogen removal technologies. The recent research of OLAND was reviewed, and its microbial mechanism as well as its applicable prospect was remarked in this paper.

Ammonia↗
PubMed2003

[The observation of the lymphocyte phenotype change in different lymphoid tissues of mice after intranasal immunization with bivalent Shigella vaccines].

AIM: To observe the changes of lymphocyte phenotype in different lymphoid tissues of mice at various time after intranasal immunization with bivalent Shigella vaccines. METHODS: BALB/c mice were randomly divided into three groups, 30 mice per group. Mice were intranasally immunized respectively with PBS, FSM-2117 or FS-5416 four times (bacterial number was sequentially 5x10(6), 1x10(7),4x10(7)and 4x10(7)CFU/mouse) with two week intervals. Lymphocytes in nasal associated lymphoid tissue (NALT), nasal passage(NP), spleen or Peyer's patch (PP) were isolated on the 7th,30th and 90th day after the last immunization. The phenotype of the lymphocytes was detected by FACS. RESULTS: CD3(+) T cells in NALT, NP and PP increased significantly on the 7th day after the immunization, in which most were CD4(+)T cells. B220(+) cells and CD3(+) T cells increased notably in spleens of FSM-2117 group and FS-5416 group, respectively. The same phenotypic changes still maintained in the NALT, NP and spleen on the 30th day after immunization, but only present in NALT and NP on the 90th day. CONCLUSION: Intranasal inoculation with the two bivalent Shigella vaccines can effectively induce immune responses in different mucosal sites and systematically which can durate for a long time and start to weaken from the tissues distal from nose to those proximal.

Administration, Intranasal↗
PubMed2002

[The experimental study of bone marrow mesenchymal stem cells on the repair of skin wound combined with local radiation injury].

OBJECTIVE: To explore the effects of swine bone marrow derived mesenchymal stem cells (MSC) on the repair of skin wound combined local irradiation injury and theirs mechanism. METHODS: MSC were isolated from the adult swine bone marrow and autologous MSC were directly transplanted into the local site full thickness skin incision round wounds combined with 20 Gy irradiation. By means of laser confocal microscopy, quantitative collagen measurement, ELSIA, fibroblasts scrap test, RT-PCR technology and so on in order to observe the effects of MSC promote the repair of wound and theirs mechanism. RESULTS: Transplanted autologous MSC into local skin wound combined with 20 Gy irradiation could accelerate the speed of wound healing, the healing time moved up 3 - 4 days. The granule tissues were abundant in the wounds and the content of collagen was increased in MSC groups. On one hand, MSC attracted the inflammatory cells and repaired cells to immigrate into wounds by themselves or secretion of IL-6, IL-8 and G-CSF and thus initiated the repairing processes. On the other hand, the wound microenviroment induced the proliferation and changes of I collagen mRNA expression of MSC showed that MSC could secrete extracellular matrix or differentiate into fibroblast. CONCLUSION: Local transplanted MSC promoted the repair of skin wounds combined with irradiation injury. The promotion effects were achieved by the interaction between MSC and wound microenviroment.

Animals↗
PubMed2002

Bioadhesive polysaccharide in protein delivery system: chitosan nanoparticles improve the intestinal absorption of insulin in vivo.

There are many ongoing investigations to improve the oral bioavailability of peptide and protein formulations. Bioadhesive polysaccharide chitosan nanoparticles (CS-NPs) would seem to further enhance intestinal absorption of them. In this study, Insulin-loaded CS-NPs were prepared by ionotropic gelation of CS with tripolyphosphate anions. Its particle size distribution and zeta potential were determined by photon correction spectroscopy and laser Dopper anemometry. The ability of CS-NPs to enhance intestinal absorption of insulin and increase the relative pharmacological bioavailability of insulin was investigated by monitoring the plasma glucose level of alloxan-induced diabetic rats after oral administration of various doses of insulin-loaded CS-NPs. CS-NPs had a particle size in the range of 250-400 nm and its polydispersity index was smaller than 0.1, positively charged, stable. Insulin association was found up to 80% and its in vitro release showed a great initial burst with a pH-sensitivity property. CS-NPs enhanced the intestinal absorption of insulin to a greater extent than the aqueous solution of CS in vivo. Above all, after administration of 21 I.U./kg insulin in the CS-NPs, the hypoglycemia was prolonged over 15 h and the average pharmacological bioavailability relative to SC injection of insulin solution was up to 14.9%.

Adhesives↗