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Biomedical subjects

Qing Zhang

Publications and source records attributed to Qing Zhang.

At least 163 records · Page 9Linked to original sources
PubMed2004

Expression of the soluble extracellular domain of human thrombopoietin receptor using a maltose-binding protein-affinity fusion system.

The thrombopoietin (TPO) receptor (Mpl) belongs to the family of ligand-dependent cytokine receptors and plays a functional role in regulating platelet production. The signaling capacity largely depends on the binding of TPO to the extracellular domains of the TPO receptor (Mpl-EC). Because the expression level of Mpl in human tissue is very low, studies on the functional and spatial characteristics of its ligand-binding sites have been limited. In the present study, we report the expression and purification of Mpl-EC as a fusion with the maltose-binding protein (MBP), designated MBP-Mpl-EC. MBP-Mpl-EC was expressed in the cytoplasm of Escherichia coli as a soluble fusion protein. Specific binding of TPO to purified MBP-Mpl-EC was demonstrated by a dot-blot assay and surface plasmon resonance. We conclude that bacterial expression of MBP-Mpl-EC yields large amounts of protein with correct folding and that it can be used for further structure and function analyses.

Carrier Proteins↗
PubMed2004

[Rotavirus surveillance data from Kunming Children's Hospital, 1998 - 2001].

OBJECTIVE: To study the epidemiological status on rotavirus diarrhea in Kunming to improve the rotavirus vaccine immunization program. METHODS: A hospital-based sentinel surveillance program for rotavirus was set up among children less than 5 years old with acute diarrhea in Kunming Children's Hospital. Clinical information and fecal specimens were collected and rotavirus were detected by polyacrylamide gel electrophoresis (PAGE) and/or enzyme linked immunosorbent assay (ELISA). Positive specimens were further serotyped or genotyped by ELISA and/or RT-PCR. RESULTS: During the three years of surveillance, 466 specimens were collected. Rotavirus were detected on 246 (52.8%) specimens. 97% of the rotavirus diarrhea cases occurred among children less than 2 years old. There was a peak of admissions for rotavirus diarrhea cases between October and December which accounted for 48% of all the rotavirus hospitalizations each year. Among 204 specimens with G serotyping, the predominant strain was serotype G1 (47.5%) followed by G2 (17.6%), G3 (15.7%), G9 (4.9%) and G4 (1.0%). Mixed infection (2.5%) were rare and 22 specimens (10.8%) remained non-typeable. P genotyping showed P[4], P[8] and P[6] were the most common strains, accounting for 29.3%, 27.6% and 13.8% respectively. P[4]G2 was the most common strain which accounted for 34.1% (14/41) followed by P[8]G1 (29.3%) and P[6]G9 (12.2%). Another 7 uncommon P-G combinations were also identified. CONCLUSION: Rotavirus was the major cause of acute diarrhea in Kunming. An effective rotavirus vaccine for prevention and control of rotavirus diarrhea should be developed.

Child, Preschool↗
PubMed2004

[Studies on the changes in the interleukin-13 expression and on activator protein-1 activity in rat pulmonary tissue with acute lung injury induced by endotoxin].

OBJECTIVE: To investigate the changes in plasma level of interleukin-13 (IL-13) and the changes in the pulmonary IL-13 mRNA content and the pulmonary activator protein-1 (AP-1) activity of the rats inflicted with acute lung injury (ALI) induced by lipopolysaccharide (LPS), so as to explore the relationship between IL-13 expression and AP-1 activity. METHODS: One hundred and twenty Wistar rats were employed in the study and were randomly divided into A (2 mg/kg), B (4 mg/kg), C (6 mg/kg) and D (8 mg/kg) groups according to different dosage of LPS administration and a control group (NS group) at each observing time point. The rats were observed at 1, 2, 4 and 6 postburn hours (PBHs) and every 6 rats were deployed in every group and each time points. A model of systemic inflammatory response syndrome-acute lung injury (SIRS-ALI) was replicated in Wistar rats. The plasma content of IL-13 was assayed by enzyme-linked immunosorbent assay (ELISA), and the pulmonary tissue content of IL-13 mRNA and AP-1 activity by reverse transcriptase-polymerase chain reaction (RT-PCR) and electrophoretic mobility shift assays (EMSA). RESULTS: The plasma content of IL-13, pulmonary content of IL-13 mRNA and AP-1 activity increased simultaneously after LPS administration. All the above indices were significantly different statistically between the LPS groups and the control group (P < 0.05 - 0.01). The plasma level of IL-13 and pulmonary tissue mRNA content and AP-1 activity in A, B, C and D groups were increased significantly with peak levels at 2 PBHs. CONCLUSION: The pulmonary AP-1 activity increased with the enhanced expression of IL-13, which was related to the development of SIRS-ALI.

Acute Lung Injury↗
PubMed2004

[Studies on the expression of mRNA of anti- and pro-inflammatory cytokines in acute lung injury induced by lipopolysaccharide in rat].

OBJECTIVE: To study the role of pro-inflammatory cytokines including tumor necrosis factor-alpha(TNF-alpha), interleukin-1beta(IL-1beta), IL-6, and anti-inflammatory cytokines including IL-4, IL-10, and IL-13 in acute lung injury(ALI). METHODS: Reverse transcription-polymerase chain reaction(RT-PCR) were used to assess the expressions of mRNA of TNF-alpha, IL-1beta, IL-6, IL-4, IL-10 and IL-13 in the lung tissue after lipopolysaccharide challenge. RESULTS: The expression of TNF-alpha mRNA was seen to peak at 1 hour and IL-6 mRNA at 4 hours in lung tissue after the challenge. The highest expression of mRNA of other cytokines, such as IL-1beta, IL-4, IL-10 and IL-13 in lung tissue appeared 2 hours after LPS-induced lung injury. CONCLUSION: TNF-alpha is an early presenting cytokine in ALI, and IL-6 may play an important role in delayed development of ALI. The over-expression of anti-inflammatory cytokines IL-4, IL-10 and IL-13 may act as promoters rather than protectors in amplification of inflammatory process.

Acute Lung Injury↗
PubMed2004

Rational redesign of inhibitors of furin/kexin processing proteases by electrostatic mutations.

AIM: To model the three-dimensional structure and investigate the interaction mechanism of the proprotein convertase furin/kexin and their inhibitors (eglin c mutants). METHODS: The three-dimensional complex structures of furin/kexin with its inhibitors, eglin c mutants, were generated by modeller program using the newly published X-ray crystallographical structures of mouse furin and yeast kexin as templates. The electrostatic interaction energy of each complex was calculated and the results were compared with the experimentally determined inhibition constants to find the correlation between them. RESULTS: High quality models of furin/kexin-eglin c mutants were obtained and used for calculation of the electrostatic interaction energies between the proteases and their inhibitors. The calculated electrostatic energies of interaction showed a linear correlation to the experimental inhibition constants. CONCLUSION: The modeled structures give good explanations of the specificity of eglin c mutants to furin/kexin. The electrostatic interactions play important roles in inhibitory activity of eglin c mutants to furin/kexin. The results presented here provided quantitative structural and functional information concerning the role of the charge-charge interactions in the binding of furin/kexin and their inhibitors.

Animals↗
PubMed2004

[Study on the phenomenon of regionally pathological difference of otitis media and its clinical significance].

OBJECTIVE: To study the feature and difference of severity of pathological changes in different areas of the middle ear cleft with otitis media (OM) and its pathogenesis and clinical significance. METHODS: The temporal bone slides of 290 ears with OM with inflammatory effusion had been studied histopathologically under microscope. The histopathological change in different areas has been comparatively observed. 256 cases with various forms of chronic otitis media (COM) have been studied with high-resolution CT, and 189 cases with COM were observed during operation, stressing on the difference of pathogical changes in different areas. RESULTS: In the process of OM, the mucosa of the eustachian tube almost has no inflammatory pathological changes, and in hemi-anterior and infer-posterior mesotympanum area was much lightly and reversible pathological change. But the pathological changes in the ossicular chain area was much more serious than the other two areas, and was irreversible or intractable such as granulation tissue, cholesteatoma etc. CONCLUSIONS: Because of the historical and anatomical distinction difference between anterior and posterior area of the middle ear cleft and blockage of internal ventilation/draining system in process of OM, the stagnancy of inflammatory effusion and formation of granulation tissue in posterior area are the main cause leading to the phenomenon of regionally pathological difference in different areas of the middle ear clefts.

Ear, Middle↗
PubMed2004

[Clinical study on treatment of advanced stage non-small cell lung cancer by guben xiaoliu capsule].

OBJECTIVE: To observe the therapeutic effect of Guben Xiaoliu Capsule (GXC) in treating advanced stage non-small cell lung cancer (NSCLC). METHODS: One hundred and ninety-eight NSCLC in-patients were divided into the integrative treated group [Group A, 54 patients treated with chemotherapy (CT) plus GXC], the TCM treated group (Group B, 96 patients treated with GXC alone) and the chemotherapeutic group (Group C, 48 patients treated with CT alone). Randomized controlled observation was applied to the Group A and C. The clinical effect, quality of life (QOL), adverse reaction and survival period in the three groups were observed. RESULTS: The immediate effective rate (CR + PR) in the Group A, B and C was 16.7%, 3.1% and 8.3%, respectively, in the Group A, it was better than that in the other two groups (P < 0.05). The improvement of clinical symptoms and QOL in the Group A and B were superior to those in the Group C (P < 0.05). The median survival rate in the three groups was 12, 15 and 9 months, respectively, the 1-, 2- and 3-year survival rate in Group A being 57.4%, 11.1% and 3.7%, respectively, in Group B, 67.7%, 9.4% and 3.1%, and in (Group C, 39.6%, 4.2% and 0, respectively, comparison between the three groups showed that the survival rates in the former two were higher than those in Group C (P < 0.05). Moreover, the incidence rate and degree of CT toxicity were milder in Group A than those in Group C (P < 0.05). CONCLUSION: GXC has definite effect in treating NSCLC, it could raise the QOL, prolong the survival period of patients, also reduce the toxicity and enhance the efficacy of CT.

Adult↗
PubMed2004

[Phylogenetic analysis of enterovirus 71 isolated from patients with hand, foot and mouth disease in Guangdong and Fujian provinces, 2000-2001].

OBJECTIVE: To identify enterovirus 71 (EV71) strains isolated from patients with hand, foot and mouth disease (HFMD) in Guangdong and Fujian provinces from 2000 to 2001 by using phylogenetic analysis. METHODS: All 25 samples were first tested for enteric viruses by RT-PCR using enterovirus specific primers EV-1 and EV-2, and then were identified for EV71 by RT-PCR using EV71 specific primers 159S and 162A. The amplicons of 485bp segment (part of the VP1 gene) were cloned into pGEM-T and sequenced. A phylogenetic tree was constructed by comparison of the sequences with other 12 EV71 strains isolated from China, Japan, Hungary, and the United States including the prototype BrCr. RESULTS: The positive rate of EV71 was about 20%. The sequence analysis showed that the new isolate (GZH2000) shared 94%-96% nucleotide identity with three strains isolated in 1998 and 2000, and 91% with a strain isolated in 1987 from Chinese mainland, but shared only 82%-84% homology with EV71 isolates studied abroad. CONCLUSIONS: EV71 is one of the important pathogens of HFMD in south China. The strains isolated from mainland were closely related with most isolates from Taiwan, but different from most EV71 strains reported abroad. The symptoms of EV71 infection in mainland were not as intensive as those described in Taiwan's outbreak.

Adolescent↗
PubMed2004

[Determination of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in newsprints and copy papers by HRGC/HRMS].

The concentrations of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) in newsprints and copy papers which included blank and printed paper samples were determined by isotope dilution and high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS). All of the paper samples collected at random were extracted with organic solvents and the extracts were cleaned up successively by three different chromatographic columns. The results indicated that the total concentrations of PCDD/ Fs in newsprints were higher than those in copy papers, but the total toxicity equivalent (TEQ) values of newsprint samples were lower than those in copy paper samples. In addition, for both papers, the concentrations of PCDD/Fs in printed papers were higher than the blank papers. Moreover, the patterns of PCDD/Fs in newsprint samples and copy paper samples were different. The total international TEQ values of PCDD/Fs in newsprints and printed newsprints were 0.48 ng/kg and 0.61 ng/kg, respectively. Moreover, the total TEQ values of PCDD/Fs in copy paper and printed copy paper samples were 0.74 ng/kg and 0.79 ng/kg, respectively. The recoveries of 13C labeled 2, 3 ,7, 8-substituted PCDD/Fs spiked before extraction into all paper samples were between 49.82% and 131.34%.

Benzofurans↗
PubMed2004

[Prediction of soil adsorption coefficients of organic compounds in a wide range of soil types by soil column liquid chromatography].

Using the methanol-water mixtures as mobile phases of soil column liquid chromatography (SCLC), prediction of soil adsorption coefficients (K(d)) by SCLC was validated in a wide range of soil types. The correlations between the retention factors measured by SCLC and soil adsorption coefficients measured by batch experiments were studied for five soils with different properties, i.e., Eurosoil 1#, 2#, 3#, 4# and 5#. The results show that good correlations existed between the retention factors and soil adsorption coefficients for Eurosoil 1#, 2#, 3# and 4#. For Eurosoil 5# which has a pH value of near 3, the correlation between retention factors and soil adsorption coefficients was unsatisfactory using methanol-water as mobile phase of SCLC. However, a good correlation was obtained using a methanol-buffer mixture with pH 3 as the mobile phase. This study proved that the SCLC is suitable for the prediction of soil adsorption coefficients.

Adsorption↗
PubMed2003

A novel multi-walled carbon nanotube-based biosensor for glucose detection.

The bioelectrochemical characteristics of a novel multi-walled carbon nanotube (MWNT)-based biosensor for glucose detection are studied and compared with those of glassy carbon (GC)-based biosensor. The MWNT-based biosensor exhibits a strong glucose response at applied potentials of 0.65 and 0.45 V versus Ag/AgCl, respectively, while GC-based biosensor shows a weak glucose response at 0.65 V and no response at 0.45 V. Besides, the MWNT-based biosensor shows a high stability of 86.7% of the initial activity to glucose after four-month storage, much higher than 37.2%, the corresponding value for a GC-based biosensor. The detection mechanism of the MWNT-based biosensor is also discussed in detail.

Biosensing Techniques↗
PubMed2003

Purification and characterization of a novel carbaryl hydrolase from Aspergillus niger PY168.

A fungus capable of using carbaryl as the sole source of carbon and energy was isolated from a soil enrichment, and characterized as Aspergillus niger and designated strain PY168. A novel carbaryl hydrolase from cell extract was purified 262-fold to apparent homogeneity with 13.6% overall recovery. It had a monomeric structure with a molecular mass of 50,000 Da and a pI of 4.6, and the enzyme activity was optimal at 45 degrees C and pH 7.5, The activities were strongly inhibited by Hg(2+), Ag+, rho-chloromercuribenzoate, iodoacetic acid, diisofluorophosphate and phenylmethylsulfonyl fluoride but not EDTA and phenanthroline. The purified enzyme hydrolyzed various N-methylcarbamate insecticides. Carbaryl is the preferred substrate.

Aspergillus niger↗
PubMed2003

A highly enantioselective phase-transfer catalyzed epoxidation of enones with a mild oxidant, trichloroisocyanuric acid.

The enantioselective epoxidation can be carried out using trichloroisocyanuric acid (TCCA) as oxidant in the presence of chiral quaternary ammonium salt as a phase-transfer catalyst; treatment of chalcone derivatives with TCCA under mild conditions afforded the corresponding epoxy ketones in good yields with moderate to excellent enantioselectivities of up to 96%.

Journal Article↗
PubMed2003

Identification of the key amino acids of glial cell line-derived neurotrophic factor family receptor alpha1 involved in its biological function.

Glial cell line-derived neurotrophic factor (GDNF) plays a critical role in neurodevelopment and survival of midbrain dopaminergic and spinal motor neurons in vitro and in vivo. The biological actions of GDNF are mediated by a two-receptor complex consisting of a glycosylphosphatidylinositol-linked cell surface molecule, the GDNF family receptor alpha1 (GFRalpha1), and receptor protein tyrosine kinase Ret. Although structural analysis of GDNF has been extensively examined, less is known about the structural basis of GFRalpha1 function. In this study, based on evolutionary trace method and relative solvent accessibility prediction of residues, a set of trace residues that are solvent-accessible was selected for site-directed mutagenesis. A series of GFRalpha1 mutations was made, and PC12 cell lines stably expressing different GFRalpha1 mutants were generated. According to the survival and differentiation responses of these stable PC12 cells upon GDNF stimulation and the GDNF-GFRalpha1-Ret interaction assay, residues 152NN153, Arg259, and 316SNS318 in the GFRalpha1 central region were found to be critical for GFRalpha1 binding to GDNF and eliciting downstream signal transduction. The single mutation R259A in the GFRalpha1 molecule simultaneously lost its binding ability to GDNF and Ret. However N152A/N153A or S316A/N317A/S318A mutation in the GFRalpha1 molecule still retained the ability to bind with Ret. These findings suggest that distinct structural elements in GFRalpha1 may be involved in binding to GDNF and Ret.

Amino Acid Substitution↗
PubMed2003

Constitutive activation of Stat5b contributes to carcinogenesis in vivo.

The development of more effective prevention and treatment strategies for solid tumors is limited by an incomplete understanding of the critical growth pathways that are activated in carcinogenesis. Signal transducers and activators of transcription (STAT) proteins have been linked to transformation and tumor progression. Studies to date have not elucidated clear and distinct roles for Stat5genes (Stat5a and Stat5b) in human epithelial cancers. We analyzed the role of Stat5a/b isoforms in squamous cell carcinoma of the head and neck using expression and activation studies in human tissues and in a xenograft model after selective targeting. In a xenograft model, blockade of Stat5b, but not Stat5a, using antisense oligonucleotides resulted in tumor growth inhibition and abrogation of Stat5 target genes in vivo. Blockade of the epidermal growth factor receptor resulted in partial abrogation of Stat5 activation, thus linking epidermal growth factor receptor to Stat5 in vivo. In tissues from 33 individuals with head and neck cancer, Stat5 activation levels were correlated with progression to a malignant phenotype, where increased expression and phosphorylation of Stat5b were detected consistently in tumors compared with their epithelial counterparts. Thus, constitutive activation of Stat5b contributes to squamous cell tumorigenesis and may serve as a therapeutic target.

Animals↗
PubMed2003

Mitogenic effects of gastrin-releasing peptide in head and neck squamous cancer cells are mediated by activation of the epidermal growth factor receptor.

Head and neck squamous cell carcinomas (HNSCC) are characterized by upregulation of the epidermal growth factor receptor (EGFR), where EGFR serves as a potential therapeutic target. We previously reported that a gastrin-releasing peptide/gastrin-releasing peptide receptor (GRP/GRPR) autocrine growth pathway is activated early in HNSCC carcinogenesis. In the present study, we examined the mechanism of EGFR activation by GRP/GRPR in HNSCC proliferation. In HNSCC cells that express elevated levels of both GRPR and EGFR, we found that GRP induced rapid phosphorylation of EGFR as well as p44/42-MAPK activation. Using several EGFR-specific tyrosine kinase inhibitors and cells derived from EGFR knockout mice, we demonstrated that GRP-induced p44/42-MAPK activation was dependent upon EGFR activation. Further investigation demonstrated that cleavage of transforming growth factor-alpha (TGF-alpha) by matrix metalloproteinases mediated GRP-induced MAPK activation. In addition, HNSCC proliferation stimulated by GRP was eliminated upon specific inhibition of EGFR or MEK, and GRP failed to stimulate proliferation in EGFR-deficient cells. These results imply that the mitogenic effects of GRP in HNSCC are mediated by extracellular release of TGF-alpha and require the activation of an EGFR-dependent MEK/MAPK-dependent pathway.

Animals↗