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Qian Chen

Publications and source records attributed to Qian Chen.

At least 91 records · Page 5Linked to original sources
PubMed2003

Eosinophil-derived neurotoxin (EDN), an antimicrobial protein with chemotactic activities for dendritic cells.

Recent publications have highlighted the chemotactic activities of antimicrobial proteins derived from the granules of neutrophils and basophils. Eosinophil granules also contain antimicrobial proteins. One of them is eosinophil-derived neurotoxin (EDN), a protein belonging to the ribonuclease A (RNase A) superfamily, which has recently been found to have antiviral activity in vitro. We found that EDN was selectively chemotactic for dendritic cells (DCs). The DC chemotactic activity of EDN was inhibited by either pretreatment of DCs with pertussis toxin or by simultaneous addition of placental RNase inhibitor to inhibit the activity of EDN. EDN was not chemotactic for leukocytes other than DCs. Mouse eosinophil-associated RNase 2 (mEAR2), one of a cluster of divergent orthologs of human EDN, was also chemotactic for human as well as mouse DCs. Sequence and mutational analysis demonstrated the importance of the N-terminal region of mEAR2 in mediating its chemotactic effect on DCs. EDN also induced the activation of p42/44 mitogen-activated protein kinase (MAPK) in DCs. Furthermore, injection of mEAR2 into the air pouches of mice resulted in the recruitment of DCs into the air pouches. Thus, EDN and its mouse ortholog, mEAR2, are eosinophil granule-derived antimicrobial RNases that function as chemoattractants for DCs in vitro and in vivo.

Animals↗
PubMed2003

Complete sequence of virulence plasmid pJM1 from the marine fish pathogen Vibrio anguillarum strain 775.

The virulence plasmid pJM1 enables the fish pathogen Vibrio anguillarum, a gram-negative polarly flagellated comma-shaped rod bacterium, to cause a highly fatal hemorrhagic septicemic disease in salmonids and other fishes, leading to epizootics throughout the world. The pJM1 plasmid 65,009-nucleotide sequence, with an overall G+C content of 42.6%, revealed genes and open reading frames (ORFs) encoding iron transporters, nonribosomal peptide enzymes, and other proteins essential for the biosynthesis of the siderophore anguibactin. Of the 59 ORFs, approximately 32% were related to iron metabolic functions. The plasmid pJM1 confers on V. anguillarum the ability to take up ferric iron as a complex with anguibactin from a medium in which iron is chelated by transferrin, ethylenediamine-di(o-hydroxyphenyl-acetic acid), or other iron-chelating compounds. The fatDCBA-angRT operon as well as other downstream biosynthetic genes is bracketed by the homologous ISV-A1 and ISV-A2 insertion sequences. Other clusters on the plasmid also show an insertion element-flanked organization, including ORFs homologous to genes involved in the biosynthesis of 2,3-dihydroxybenzoic acid. Homologues of replication and partition genes are also identified on pJM1 adjacent to this region. ORFs with no known function represent approximately 30% of the pJM1 sequence. The insertion sequence elements in the composite transposon-like structures, corroborated by the G+C content of the pJM1 sequence, suggest a modular composition of plasmid pJM1, biased towards acquisition of modules containing genes related to iron metabolic functions. We also show that there is considerable microheterogeneity in pJM1-like plasmids from virulent strains of V. anguillarum isolated from different geographical sources.

Animals↗
PubMed2003

Many chemokines including CCL20/MIP-3alpha display antimicrobial activity.

Previous studies have demonstrated that beta-defensins exhibit chemotactic activity by sharing the chemokine receptor CCR6 with the CC chemokine ligand CCL20/macrophage-inflammatory protein-3alpha (MIP-3alpha). Structural analysis of CCL20/MIP-3alpha revealed that most of the positively charged residues are concentrated at one area of its topological surface, a characteristic considered to be important for the antimicrobial activity of defensins. Here, we report that similar to defensins, CCL20/MIP-3alpha has antimicrobial effects on Escherichia coli, Pseudomonas aeruginosa, Moraxella catarrhalis, Streptococcus pyogenes, Enterococcus faecium, Staphylococcus aureus, and Candida albicans. Additionally, by screening a total of 30 human chemokines, we have identified an additional 17 human chemokines, which exhibit antimicrobial activity in vitro. Collectively, about two-thirds of the chemokines investigated so far has the capacity to kill microorganisms in vitro, suggesting that antimicrobial activity may be another host-defense function for certain chemokines. Comparison of the structural characteristics between antimicrobial and nonantimicrobial chemokines suggests that topological formation of a large, positively charged electrostatic patch on the surface of the molecule is likely to be a common structural feature of antimicrobial chemokines.

Anti-Bacterial Agents↗
PubMed2003

[Epidemiological characteristics of severe acute respiratory syndrome in Tianjin and the assessment of effectiveness on measures of control].

OBJECTIVE: To analyze the epidemiologic characteristics of severe acute respiratory syndrome (SARS) and to evaluate the effectiveness on its major control measures in Tianjn. METHODS: Adopting two case reports 1 and 2, designed by the Tianjin Centers for Disease Control and Prevention to develop a unified case-tracing table including the map of the distribution of close contacts to SARS patients. With those methods, investigation on patients and their close contacts at hospital wards, families, communities and institutions of the patients were carried out. RESULTS: From April 13 through May 8, 2003, there were 175 SARS cases including imported ones, were identified with an incidence rate of 1.9 cases per 100,000. Among them, 14 died with a fatality of 8.0%. The whole process of epidemic in Tianjin was less than one month with the following features: (1) 93.7% of the total SARS cases in Tianjin were directly or indirectly transmitted by a super-spreader. (2) 68.6% of the total SARS patients were concentrated in 3 hospitals A, B and C which was menifastated in 'clustering'. Through study on the rest of the SARS patients, results showed that 16.8% of them were transmitted through family close contact and 2.3% due to contact to colleagues. However, 12.6% of the patients were not able to show evidence that they had any contact to a diagnosed SARS patient. At the early stage of the epidemic, a number of medical practitioners were infected, taking up 38.2% of the total SARS cases. Among the total number of 1 975 medical workers who participated in the SARS medical cares and treatments, 3.4% of them got infected. During the outbreak, all index cases and chains of transmission seemed to be clear, with only 3 patients not able to be traced for the source of infection, taking up 2% of the total SARS patients in Tianjin. Among the 10 index cases, only the super spreader and another one index case transmitted the virus to their contacts but the rest of index cases did not cause any secondary infection. CONCLUSION: Though SARS is clinically severe and can be spreaded quickly, the epidemic can be under control within a short period of time if chains of SARS transmission are broken down and effective measures as isolation and quarantine against patients as well as underscoring awareness among the publics in a scientific way, being carried out.

Adolescent↗
PubMed2003

[Clinical characteristics of obstructive sleep apnea syndrome in children].

OBJECTIVE: To explore the clinical features and diagnosis of obstructive sleep apnea syndrome (OSAS) in children. METHODS: Sixty children with OSAS were reviewed, every patient was monitored with polysomnography (PSG) for 7 hours at night for 11 parameters, including the longest apnea time (LAT), apnea and hypopnea index (AHI), the lowest oxygen saturation (SaO(2)), and snore index etc., the parameters of the 2 groups were compared. Meanwhile, tonsillectomy and adenoidectomy were performed for 40 cases of OSAS, and the parameters obtained before and after operation were analyzed. RESULTS: Adenotonsillar hypertrophy and the loud snoring during sleep were found in all cases. The mean values of the PSG parameters were as follows: the longest apnea time was 53 (8-178) seconds (s); the total time of apnea was 310.5 (26-5,260) s; the time of apnea was 26 (3-240) s; the longest hypopnea time was 41 (5-94) s; the total times of hypopnea was 170 (5-2,860) s; the time of hypopnea was 10 (1-85); the apnea index was 4.1 (0.5-25.9); the hypopnea index was 1.4 (0-16.1); the apnea and hypopnea index (AHI) was 6.8 (0.5-38.2); the snore index was 81.7 (1.3-414.8); the lowest saturation of oxygen was 0.78 (0.25-0.93). There was not statistically significant difference in the parameters between 2-7 year group and over 7 year group (P > 0.05). The parameters of postoperation group: the mean value of the longest apnea time was 15.5 (0-60) s; the total time of apnea was 56.4 (60-205) s; the time of apnea was 10.33 (0-40); the longest hypopnea time was 13.25 (0-30) s; the total times of hypopnea was 44.6 (0-73); the hypopnea time was 4.32 (0 - 30) s; the apnea index was 0.6 (0-12); the hypopnea index was 0.62 (0-4); the apnea and hypopnea index (AHI) was 1.25 (0.1-12); the snore index was 30.08 (1.8-102); the lowest oxygen saturation was 93.5% (64%-97%). Compared with preoperation groups there was a statistically significant difference (P < 0.01). Clinically effective rate of the surgeries was over 90%. CONCLUSION: Adenotonsillar hypertrophy seemed to be an important cause of OSAS in children. Snoring, dyspnea, apnea and low ventilation are the major clinical characteristics of OSAS in children. Confirmed diagnosis of the syndrome in children requires PSG recordings.

Child↗
PubMed2002

Influence of anti-alginate serum combined with gatifloxacin on mucoid pseudomonas aeruginosa biofilm morphology.

OBJECTIVE: To investigate the influence of anti-alginate serum on morphology of biofilm (BF) of mucoid Pseudomonas aeruginosa. METHODS: The modified plate culture method was used to establish a biofilm model of mucoid Pseudomonas aeruginosa in vitro. The biofilm was treated by anti-alginate serum and/or different concentrations of gatifloxacin. The samples were then detected by scanning electron microscopy (SEM) and optical microscopy after being stained with AgNO(3). A group of samples treated by none agent was used as blank control. The optical density of bacterial biofilm was determined by using computer image analysis system. RESULTS: BF was achieved on the silicon slides in all groups 7 days after the incubation of Pseudomonas aeruginosa. The silicon slides were covered by dense and black stained material in the blank group; the black stained material as mildly less in the group treated with anti-alginate serum, and much less in the group treated with gatifloxacin, and the BF was thin and only slightly stained black in the group treated with anti-alginate combined with gatifloxacin. SEM showed that the mucoid materials among bacteria was reduced and the number of bacteria was decreased and the shape of bacteria became irregular in the groups treated by anti-alginate serun and/or gatiflaxacin, especially the group treated by anti-alginate combined with gatifloxacin. Computer image analysis system showed that the mean optical density was 0.82 +/- 0.06 in the blank control group, 0.79 +/- 0.06 in anti-alginate serum group, 0.76 +/- 0.07 in of gatifloxacin group, and 0.70 +/- 0.04 in anti-alginate serum combined with gatifloxacin group. CONCLUSION: Anti-alginate serum affects the structure and morphology of the biofilm of mucoid Pseudomonas aeruginosa and destroys the biofilm structure when combined with gatifloxacin.

Alginates↗
PubMed2002

Identification, characterization, and functional study of the two novel human members of the semaphorin gene family.

We cloned two novel human transmembrane semaphorins, (HSA)SEMA6C and (HSA)SEMA6D, that belong to the class VI subgroup of the semaphorin family. The genes for SEMA6C and SEMA6D are mapped on chromosome 1q12-21.1 and 15q21.1, respectively. Among the adult tissues, SEMA6C is expressed only in skeletal muscle, whereas SEMA6D is expressed abundantly in kidney, brain, and placenta and moderately in the heart and skeletal muscles. During murine development, neither SEMA6C nor SEMA6D was expressed in embryonic day 10.5 (E10.5) embryos, but both were highly expressed in the areas of the lateral ventricle, the striatum, the wall of the midbrain, the pons/midbrain junction, and the choroid plexus of E13 embryos. Were neurons, neither axons nor astrocytes, highly expressed both semaphorins. Three isoforms of SEMA6C and five isoforms of SEMA6D derived from alternative splicing were identified, and their expression was regulated in a tissue- and development-dependent manner. Deletion analysis indicated that a sema domain and a PSI domain are integrally necessary for correct post-translation modification and subcellular localization. The extracellular domain of SEMA6C inhibited axonal extension of nerve growth factor-differentiated PC12 cells and induced the growth cone collapse of chicken dorsal root ganglion, rat hippocampal neurons, and rat cortical neurons in a dose-responsive manner. SEMA6D acted like SEMA6C except it had no significant effect on the growth cones of rat cortical neurons.

Alternative Splicing↗
PubMed2002

[Adenovirus-mediated NT3 gene transfer protects spiral ganglion neurons from degeneration after noise trauma].

Numerous studies have shown that the health of spiral ganglion neurons is highly important for hearing. As a trophic factor of spiral ganglion neurons, neurotrophin 3 (NT3) is a potential candidate for prevention of spiral ganglion neuron degeneration in human. In our experiments, efficient transduction and long term expression of foreign gene of cochlea cells has been found with adenovirus carried lacZ gene (Ad-lacZ). A model of guinea pig deafness was made by intense noise exposure, which destroyed the entire organ of Corti in the middle part of the cochlea. Seven days after noise exposure, the animals were anesthetized and 1 10(8) recombinant adenoviral particles were injected into the scala tympani through the round window membrane. Animals inoculated with neurotrophin 3 adenovirus(Ad-NT3) were designated as the experimental group, animals inoculated with Ad-lacZ vector served as the control group. Four weeks after the inoculation of the virus, NT3 immunoreactivity was observed in the Ad-NT3 inoculated group. HE histochemical staining results showed that in the Ad-lacZ injected group, the neuronal degeneration was severer and the density of spiral ganglion neurons was significantly lower than those in the Ad-NT3 injected group. Our results demonstrate that with adenovirus-mediated overexpression NT3 may be developed into a new treatment to prevent secondary spiral ganglion degeneration following the damage to Corti organ.

Adenoviridae↗
PubMed2002

Activation of protein kinase Ceta triggers cortical granule exocytosis in Xenopus oocytes.

Previous work has shown that phorbol esters or diacylglycerol trigger cortical granule exocytosis in Xenopus oocytes. We sought to identify the isoform(s) of protein kinase C (PKC) that mediate(s) this regulated secretory event. Because this process is initiated by lipid activators of PKC but is independent of calcium ions, we focused on the family of novel (calcium-independent) PKCs. Pharmacological investigations using Gö6976 and Gö6983 tended to exclude PKCdelta, epsilon and mu as secretory triggers. Subcellular fractionation and immunoblot data revealed that these oocytes expressed all five members of the novel PKC family, but it was only PKCeta that colocalized with cortical granules. Finally, expression of wild type or constitutively active forms of PKCdelta and eta strongly supported the conclusion that it is PKCeta that initiates cortical granule exocytosis in these cells. These observations represent an important step in identifying the mechanism of secretory triggering in this system.

Animals↗
PubMed2002

Stimulation of matrix metalloprotease 3 release from human chondrocytes by the interaction of stromal cell-derived factor 1 and CXC chemokine receptor 4.

OBJECTIVE: The chemokine family of secreted proteins regulates cellular activities through interaction with G protein-coupled chemokine receptors. The aim of this study was to analyze the role of a chemokine stromal cell-derived factor 1 (SDF-1) and its receptor CXCR4 in rheumatoid arthritis (RA) and osteoarthritis (OA) by examining their gene expression in joint cartilage and synovium and by determining the effect of their interaction on the release of matrix metalloproteases (MMPs) from chondrocytes. METHODS: SDF-1 protein levels in synovial fluid from the knee joints of 58 RA patients, 55 OA patients, and 60 control patients without arthritis were quantified by enzyme-linked immunosorbent assay. SDF-1 and CXCR4 messenger RNA (mRNA) levels in chondrocytes and synovial fibroblasts were determined by reverse transcriptase-polymerase chain reaction. Isolated human chondrocytes were stimulated with 100 ng/ml of SDF-1, and the response was analyzed by quantifying the release of MMPs 1 and 3. RESULTS: We found that the concentration of SDF-1 in synovial fluid increased 3.57-fold in OA patients and 10.71-fold in RA patients compared with normal controls. The source of SDF-1 in synovial fluid was synovium, since SDF-1 mRNA was synthesized by synovial fibroblasts but not by chondrocytes. Conversely, CXCR4 was expressed by chondrocytes but not by synovial fibroblasts. The interaction of SDF-1, which was abundant in synovial fluid from RA and OA patients, with CXCR4-positive chondrocytes resulted in a specific elevation of the release of the cartilage matrix-degrading enzyme MMP-3 (stromelysin 1). CONCLUSION: Our findings suggest a novel mechanism by which synovial cells induce degradation of cartilage matrix through SDF-1 signaling in RA and OA.

Adult↗
PubMed2002

[Isolation and identification of proteins with anti-tumor and fibrinolysogen kinase activities from Eisenia foetida].

Proteins from Eisenia foetida possess many biological activities. A group of proteins precipitated by ethanol were isolated and purified by Sephadex G-75 and HiPrep 16/60 DEAE columns, then identified by one- or two- dimensional electrophoresis and mass spectrometry. 2D gel experiments displayed that the pI of proteins from Eisenia foetida were mainly from 3.0 to 4.0. Anti-tumor and kinase activities were determined by in vitro experiments. The enthanol fraction D2(8) showed both of the activities. These ethanol-precipitated proteins were identified further by native polyacrylamide electrophoresis, the protein spots were cut off from gels and digested by trypsin, the peptide mass fingerprints (PMFs) were determined by mass spectrometry. PMF, molecular weight, amino acid composition and N-terminus of 6 proteins were characterized, and band 9 was identified as D2(8). The results suggested that there exist proteins in Eisenia foetida possessed both anti-tumor and fibrinolysogen kinase activities. These methods can be used for identification of the natural bioactive proteins.

Amino Acids↗
PubMed2002

Human dendritic cells express functional formyl peptide receptor-like-2 (FPRL2) throughout maturation.

Immature and mature dendritic cells (iDC and mDC, respectively) migrate to different anatomical sites, e.g., sites of antigen (Ag) deposition and secondary lymphoid organs, respectively, to fulfill their roles in the induction of primary, Ag-specific immune responses. The trafficking pattern of iDC and mDC is based on their expression of functional chemotactic receptors and the in vivo sites expressing the corresponding ligands including chemokines and/or classical chemoattractants. In this study, we have evaluated the expression of the formyl peptide receptor like-2 (FPRL2) by human iDC and mDC. We show that iDC respond chemotactically and by Ca(2+) mobilization to N-formyl-Met-Leu-Phe and a recently identified synthetic peptide Trp-Lys-Tyr-Met-Val-D-Met (WKYMVm), whereas mDC derived from the same donor only respond to WKYMVm. Furthermore, iDC and mDC express FPRL2 mRNA and protein. As mDC do not express any other members of the human FPR subfamily, FPRL2 expressed by DC must be functional and mediate the effect of WKYMVm on DC. Indeed, treatment of iDC and mDC with WKYMVm induces the internalization of FPRL2. Thus, human myeloid DC express functional FPRL2 and maintain its expression even after maturation, suggesting that the interaction of FPRL2 and its endogenous ligand(s) may be involved in regulating DC trafficking during Ag uptake and processing in the periphery as well as the T cell-stimulating phase of the immune responses.

Amino Acid Sequence↗
PubMed2002

[Isolation, purification and analysis of polysaccharides from Adenophora potaninii Korsh].

Polysaccharides, AP-1 and AP-3, were obtained through extraction of the roots of Adenophora potaninii Korsh by hot water, followed by the isolation and purification by DEAE-cellulose and Sephadex G-200 column chromatography. It was proved to be homogeneous by gel filtration chromatography and their average MW was estimated to be 8.3 x 10(4) and 6.3 x 10(4) respectively. Analysis of sugar composition showed that AP-1 is D-glucan, while AP-3 is composed of glucose, rhamnose, arabinose and glucronic acid in the molar ratio of 5:1:1:3.

Campanulaceae↗
PubMed2002

[Protective effect of adenoviral-mediated brain derived neurotrophic factor gene on spiral ganglion].

OBJECTIVE: To observe the expression of brain derived neurotrophic factor (BDNF) in the cochlea of guinea pig, and assess the activity of BDNF in spiral ganglion cell following the damage of noise. METHODS: Twenty-seven guinea pigs were exposed to a 4 kHz narrow band noise at 135 dB SPL for 4 hours. At seven days after the noise exposure, twelve guinea pigs were inoculated with ad-BDNF, and twelve guinea pigs were inoculated with ad-LacZ, while three guinea pigs were inoculated with artificial perilymphatic fluid. The animals were sacrificed After 1 week, 4 weeks and 8 weeks, respectively. The cochlea was stained with immunohistochemisty (ABC method) to examine the expression of BDNF. The number of spiral ganglion cell was counted to assess the activity of BDNF. RESULTS: BDNF gene was expressed in whole cochlea, and the expression was obviously elevated 1 week after the adenovirus administration and reduced thereafter. The number of degenerated cells in ad-BDNF group in the eight weeks was lower than that in another two groups and the different between them was statistical significant (P < 0.01). CONCLUSION: Adenoviral-mediated brain derived neurotrophic factor can be expressed in a high level in the cochlea of guinea pig, and may prevent the cell of spiral ganglion from the damage of noise. This study lays the groundwork for alleviation of hearing loss using gene therapy.

Adenoviridae↗
PubMed2001

[Research of Typing for HLA-A, -B on Cord Blood Lymphocytes]

Serological typing for HLA-A, -B has been used for a long time. Recently with the developing of molecular biology technologies, HLA-A, -B typing is now turning to genotyping methods. In our study, the capacity of PCR-SSP in solving problems in HLA-A, -B typing with serological methes was evaluated. With this aim the serological method was compared with PCR-SSP in 102 cord blood samples, and the results showed that 18.6% of 102 cord blood samples can't give a satisfactory detection, for 14 samples, give discrepant results with the 2 methods. It is mainly due to weak expression of HLA class I cord blood lymphocytes and the cross reaction of some antigens. About B 15 group, the further study was made, it was found that most of the B 15 splits is wrongly disassigned, especially among the B62-B75, B75/*1511(+)-B75/*1511(-), B46-*1511 antigens. It was concluded that DNA typing is more preferable than serological typing, about B 15 group, the subtyping or high resolution typing can be fulfilled at first in China.

Journal Article↗
PubMed2000

Construction and Characterization of Recombinant Adenoviruses Expressing Biologically Active Human Brain-derived Neurotrophic Factor and Neurotrophin-3.

In order to deliver brain-derived neurotrophic factor(BDNF) and neurotrophin-3(NT3) into CNS to prevent or reduce degeneration of CNS neurons in human neurodegenerative diseases and neuron injuries, recombinant adenoviruses Ad-BDNF and Ad-NT3 were constructed. BDNF and NT3 genes were inserted into an E1-substituted adenovirus shuttle plasmid, respectively, and were driven by the human cytomegalovirus immediate-early gene promoter/enhancer. After cotransfection into 293 cells with the adenovirus plasmid pJM17, the recombinant adenovirus Ad-BDNF and Ad-NT3 were propagated in 293 cells via homologous recombination. After two rounds of CsCl centrifugation, the human recombinant adenovirus Ad-BDNF and Ad-NT3 were obtained with titer of 1x10(12) and 8x10(11) pfu/ml, respectively. To examine the expression of BDNF and NT3, HeLa cells were infected with Ad-BDNF and Ad-NT3, respectively. RT-PCR, Western blot and ELISA analysis results showed that BDNF and NT3 genes could be transcribed and translated in Ad-BDNF and Ad-NT3 infected HeLa cells. And the culture media containing 10% conditioned medium of Ad-BDNF and Ad-NT3 infected Hela cells could induce the neurite outgrowth from E8 dorsal root ganglion neurons.

Journal Article↗