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Biomedical subjects

G Yang

Publications and source records attributed to G Yang.

At least 181 records · Page 10Linked to original sources
PubMed2000

[The study on the role of telomerase activity in human nasopharyngeal carcinoma].

OBJECTIVE: To elucidate the role of telomerase activity in nasopharyngeal carcinoma (NPC). METHODS: Telomerase activity was detected using the telomere repeat amplification protocol(TRAP) combined with silver staining in 42 low-differentiated squamous carcinoma, 10 normal nasopharyngeal mucosae and 8 nasopharyngeal fibrohemangioma. RESULTS: Telomerase activity was detectable in 20% normal nasopharyngeal mucosae and 88.1% in NPC. The activity of telomerase was not detectable in 8 nasopharyngeal fibrohemangioma tissues. Telomerase activity was present more frequently in NPC biopsies with positive lymph node metastasis than in those without lymph node metastasis (P = 0.035). Furthermore, telomerase activity was observed more frequently in advanced NPC than in early stage (P = 0.048). However, there was no evidence to show the relationship between telomerase activity and other clinical features, such as age, gender and distant metastasis (P > 0.05). Serum EBV marker(VCA-IgA) was observed more frequently in NPC than in normal nasopharyngeal mucosae patients(P < 0.001). CONCLUSION: Telomerase activity may play a critical role in the tumorigenesis of NPC. Detection of telomerase activity combined with serological EBV markers may contribute to the screening and early diagnosis of NPC.

Adolescent↗
PubMed2000

[Construction of BPI23-Fc gamma 1 recombinant protein prokaryotic expression vector and the expression and biological assessment of BPI23-Fc gamma 1 recombinant protein].

OBJECTIVE: To construct pBV-BPI600-Fc gamma 1(700) recombinant expression vector, to transform into Escherichia coli DH5 alpha, and to induce the expression of BPI23-Fc gamma 1 anti-bacterial recombinant protein. METHODS: Genes which encode BPI23 and Fc gamma 1 were amplified by RT-PCR from mRNA that was extracted from HL-60 cell and normal human leukocytes; Recombinant cloning vector and recombinant expression vector were constructed. pBV-BPI600-Fc gamma 1(700) recombinant expression vector was transformed into the competent Escherichia coli DH5 alpha and BPI23-Fc gamma 1 recombinant protein was expressed by temperature induced method. RESULTS: (1) Expected amplified products BPI600 bp and Fc gamma 1(700) bp were obtained by RT-PCR. (2) pUC18-BPI180, pUC18-BPI420, and pUC18-Fc gamma 1(700) recombinant cloning vector were successfully constructed, and sequences were identical with the reported ones. (3) pBV-BPI600-Fc gamma 1(700) recombinant expression vector was successfully constructed, and results of the enzyme digestion analysis were identical with expected ones. (4) pBV-BPI600-Fc gamma 1(700) recombinant expression vector was transformed into the competent Escherichia coli DH5 alpha and BPI23-Fc gamma 1 recombinant protein was expressed by temperature-induced method, and its expression level was accounted for 20% of total bacterial proteins. (5) The renatured BPI23-Fc gamma 1 recombinant protein had anti-bacterial activity and biological functions of complement fixation, opsonization. CONCLUSION: pBV-BPI600-Fc gamma 1(700) recombinant expression vector was successfully constructed, and BPI23-Fc gamma 1 recombinant protein with BPI and IgGFc double biological activity was expressed in Escherichia coli.

Antimicrobial Cationic Peptides↗
PubMed2000

[Construction and expression of eukaryotic expression vector pBK-IL-1ra].

OBJECTIVE: Construction of eukaryotic vector with high expression of interleukin-1 receptor antagonist (IL-1ra) for IL-1ra gene delivery. METHODS: (1) Eukaryotic expression vector pBK-IL-1ra was constructed by recombinant DNA technique, and identified by restriction mapping enzymes, PCR, and DNA sequence analysis. (2) Expressions of the IL-1ra mRNA and IL-1ra in vitro and in vivo were detected by in situ hybridization, ELISA, and immunohistochemistry. RESULTS: (1) The correct construction of pBK-IL-1ra was identified by the method above. (2) The higher levels of IL-1ra in the supernate of COS-7 cells (24 h, (P < 0.001; 48 h, P < 0.01) and the over expression of IL-1ra mRNA (P < 0.01) and IL-1ra (P < 0.05) in the synoviocytes have been detected after 48 h of the transfection with pBK-IL-1ra. (3) The over expression of IL-1ra in muscle of the mice was detected by immunohistochemistry after 4 days of pBK-IL-1ra injection (P < 0.01) CONCLUSIONS: We have successfully constructed eukaryotic expression vector pBK-IL-1ra which could highly expressed IL-1ra in vitro and in vivo, and it offers a novel possibility in the research of IL-1ra gene therapy.

Animals↗
PubMed2000

[Comparison of infrared spectroscopy between native and binding metals' phytoplankton].

Infrared spectroscopy of native and metalbinding duckweed was compared. After binding metals, the absorbance peak around 3,400 cm-1, which reflects OH group stretching vibration, had been moved about 83 cm-1, and its absorbance was decreased. The absorbance of the dominating bands near 1,650 and 1,540 cm-1, the characteristic IR absorption of protein, was decreased. Therefore, the peak absorbance at 620 cm-1 was increased significantly by exposure to high concentration of ZnSO4 solution. So we concluded that OH group play a important role in binding zinc cation and the structure of cell walls had changed due to zinc existing. Furthermore, the process of binding metals by duckweed is physical adsorption and chemical adsorption simultaneously.

Adsorption↗
PubMed2000

[Study of polyaluminium ferric chloride (PAFC) aqueous solutions visible spectra: the relationship among their absorbance at 460 nm, basicities and total Fe(III) concentration of PAFC solutions].

The visible spectra of forty-five synthesized polyaluminium ferric chloride (PAFC) aqueous solutions with different [OH]/[Al + Fe] (B) and nAl/nFe(molar ratio) were investigated. The results showed that their absorbances A of shoulder at 460 nm are all linear interrelationship with their B. We made the curve of absorbance A of PAFC with same B vs. nAl/nFe, there was a turning point. All of these points just located at the places of pH value rising higher in pH- nAl/nFe diagrams. For these reason, we thought that these points stand for the dynamic equilibrium of OH- between the polynucleus hydroxyl Fe(III) and Al(III). These points made certain relationship among the absorbance A at 460 nm, basicities and total Fe(III) concentration of PAFC solutions.

English Abstract↗
PubMed2000

[Effect of organic tin on the morphology and mechanical properties during polyurethane-urea curing process].

The mechanical properties and morphology of crosslined PUU in bulk quasi-prepolymer process was studied by in situ FTIR. From the quantitative change of carbonyl FTIR spectra, the development of morphology between noncatalyzed and catalyzed polymerization process was discussed in detail. The effect of organic tin concentration on the mechanical properties was investigated. It showed that urea carbonyl splitted many small weak bands at different sites with increasing of organic tin concentration, and the catalyst played an important role in controlling the morphology and mechanical properties. It also showed that the mechanical properties reached extreme value when the rate constant of -NCO/-OH reaction equate the rate constant of -NCO/-OH reaction.

Catalysis↗
PubMed2000

[Nickel cation biosorping studies by yeast with dimethylglyoxime spectrophotometry].

The beer yeast as the biosorbent of Ni2+ is studied. Nickel cation was determined by dimethylglyoxime spectrophotometry. The adsorbed quantity is larger at pH = 6. The equilibrium time was 60 minutes. Salinity and Ca2+, Mg2+ have no significant effect on the biomaterial uptake. Higher the equilibrium concentration(c) is, larger the adsorbed quantity(q) of yeast is. In addition, relations between c and q were fitted with followed equations: 1/q = 0.340 + 0.0753 x 1/c, r = 0.995; lgq = 3.989 + 0.789 lgc, r = 0.995. So we concluded that the models of adsorption are fitted with Langmuir and Freundlich isotherm adsorption equation.

Adsorption↗
PubMed2000

[The effect of temperature on the structure and properties of polyurethane-urea by FTIR].

The effect of temperature on the structure and properties of polyurethane-urea was investigated by in situ FTIR. Data from FTIR spectra showed that with increasing temperature the nu NHHbonded areas decrease and the nu NHfree band areas increase. The band site of nu NHHbonded shifted to higher wavenumbers and the band site of nu NHfree keeps constant. The band site of Cfree urethane shift from 1,731 cm-1 to 1,736 cm-1. All kinds of carbonly bands sites shifted to high wavenumbers. But the band sites of amide II and the C=C in aromatic ring shifted to low wavenumbers. The properties of PUU polymers was determined by the structure of soft domains.

Polyurethanes↗
PubMed1999

A role for a melanosome transport signal in accessing the MHC class II presentation pathway and in eliciting CD4+ T cell responses.

Melanosomal membrane proteins are frequently recognized by the immune system of patients with melanoma and vitiligo. Melanosomal glycoproteins are transported to melanosomes by a dileucine-based melanosomal transport signal (MTS). To investigate whether this sorting signal could be involved in presentation of melanosome membrane proteins to the immune system, we devised a fusion construct containing the MTS from the mouse brown locus product gp75/tyrosinase-related protein-1 and full-length OVA as a reporter Ag. The fusion protein was expressed as an intracellular membrane protein, sorted to the endocytic pathway, processed, and presented by class II MHC molecules. DNA immunization with this construct elicited CD4+ T cell proliferative responses in vivo. Ag presentation and T cell responses in vitro and in vivo required a functional MTS. Mutations of either the upstream leucine in MTS or elimination of the entire MTS negated in vitro Ag presentation and in vivo T cell responses. In a mouse melanoma model, DNA immunization with MTS constructs protected mice from tumor challenge in a CD4+ T cell-dependent manner, but complete deletion of MTS decreased tumor rejection. Therefore, MTS can target epitopes to the endocytic pathway leading to presentation by class II MHC molecules to helper T cells.

Amino Acid Sequence↗
PubMed1999

Caveolin-1 expression in clinically confined human prostate cancer: a novel prognostic marker.

We demonstrated previously elevated caveolin-1 expression in metastatic mouse and human prostate cancer cells both in vitro and in vivo. In this study, we analyzed its prognostic value for progression of clinically confined human prostate cancer. Immunohistochemical staining with a caveolin-1-specific antibody was performed on routinely processed paraffin sections from 189 radical prostatectomy specimens. Caveolin-1 immunoreactivity was evaluated in association with patients' age, race, preoperative prostate-specific antigen, clinical stage, and pathological features including Gleason score, extraprostatic extension, status of surgical margins, and time to disease progression after surgery. Positive caveolin-1 immunostaining was detected in 47 of the 189 cancers (25%) and correlated positively with Gleason score, positive surgical margin, as well as lymph node involvement (P = 0.0071, 0.0267, and 0.0399, respectively). In lymph node-negative cancers (n = 162), caveolin-1 immunoreactivity predicts a shorter time to disease progression after surgery (P = 0.0033, univariate analysis). Multivariate analyses that included caveolin-1 and other prognostic pathological markers identified positive caveolin-1 immunostaining as an independent predictor for time to disease progression (P = 0.0186). Thus, our study establishes caveolin-1 as a novel prognostic marker for clinically confined human prostate cancer.

Adult↗
PubMed1999

Smoking in China: findings of the 1996 National Prevalence Survey.

CONTEXT: As the world's largest producer and consumer of tobacco products, China bears a large proportion of the global burden of smoking-related disease and may be experiencing a tobacco epidemic. OBJECTIVE: To develop an evidence-based approach supporting tobacco control initiatives in China. DESIGN AND SETTING: A population-based survey consisting of a 52-item questionnaire that included information on demographics, smoking history, smoking-related knowledge and attitudes, cessation, passive smoke exposure, and health status was administered in 145 disease surveillance points in the 30 provinces of China from March through July 1996. PARTICIPANTS: A nationally representative random sample of 128766 persons aged 15 to 69 years were asked to participate; 120298 (93.8%) provided data and were included in the final analysis. About two thirds of those sampled were from rural areas and one third were from urban areas. MAIN OUTCOME MEASURES: Current smoking patterns and attitudes; changes in smoking patterns and attitudes compared with results of a previous national survey conducted in 1984. RESULTS: A total of 41187 respondents smoked at least 1 cigarette per day, accounting for 34.1% of the total number of respondents, an increase of 3.4 percentage points since 1984. Current smoking continues to be prevalent among more men (63%) than women (3.8%). Age at smoking initiation declined by about 3 years for both men and women (from 28 to 25 years). Only a minority of smokers recognized that lung cancer (36%) and heart disease (4%) can be caused by smoking. Of the nonsmokers, 53.5% were exposed to environmental tobacco smoke at least 15 minutes per day on more than 1 day per week. Respondents were generally supportive of tobacco control measures. CONCLUSION: The high rates of smoking in men found in this study signal an urgent need for smoking prevention and cessation efforts; tobacco control initiatives are needed to maintain or decrease the currently low smoking prevalence in women.

Adolescent↗
PubMed1999

Structural and Thermodynamic Properties of Solutions of Butane in Aqueous Sodium Dodecyl Sulfate: A Study Using Neutron Scattering and Solubility Measurements.

The solubility of n-butane at a pressure of 1.013 bar in aqueous solutions of sodium dodecyl sulfate (SDS) has been measured over a range of concentration from below the critical micelle concentration (CMC) at about 8 mol kg(-1) to about 90 mol kg(-1) at three different temperatures. The free energy, enthalpy, and entropy of transfer of butane from water to the micelle were respectively -19.0 kJ mol(-1), 5.5 kJ mol(-1), and 80 J K(-1) mol(-1). At 68 mol kg(-1) a transition was found with a free energy of about -400 J mol(-1). Small-angle neutron experiments were used to study the effect of butane on the state of aggregation of the SDS. For each butane molecule incorporated into a micelle, the aggregation number of the SDS increased by an average of about 1.4 molecules. Thus, at 1.013 bar of butane and 50 mM SDS, where the solubility is about 1 butane to 10 SDS, the average micelle increases in size by about 20%, most of which comes from the additional SDS molecules. The aggregation behavior is qualitatively similar to that reported for hexane, heptane, and octane, but the effect seems to be larger for butane for a given volume of solute hydrocarbon. Small-angle scattering did not observe any substantial change in structure across the phase transition at 68 mol kg(-1). Copyright 1999 Academic Press.

Journal Article↗
PubMed1999

Steady-state kinetic characterization of RB69 DNA polymerase mutants that affect dNTP incorporation.

The function of six highly conserved residues (Arg482, Lys483, Lys486, Lys560, Asn564, and Tyr567) in the fingers domain of bacteriophage RB69 DNA polymerase (RB69 gp43) were analyzed by kinetic studies with mutants in which each of these residues was replaced with Ala. Our results suggest that Arg482, Lys486, Lys560, and Asn564 contact the incoming dNTP during the nucleotidyl transfer reaction as judged by variations in apparent Km and kcat values for dNTP incorporation by these mutants compared to those for the exonuclease deficient parental polymerase under steady-state conditions. On the basis of our studies, as well as on the basis of the crystal structure of RB69 gp43, we propose that a conformational change in the fingers domain, which presumably occurs prior to polymerization, brings the side chains of Arg482, Lys486, Lys560, and Asn564 into the vicinity of the primer-template terminus where they can contact the triphosphate moiety of the incoming dNTP. In particular, on the basis of structural studies reported for the "closed" forms of two other DNA polymerases and from the kinetic studies reported here, we suggest that (i) Lys560 and Asn564 contact the nonbonding oxygens of the alpha and beta phosphates, respectively, and (ii) both Arg482 and Lys486 contact the gamma phosphate oxygens of the incoming dNTP of RB69 gp43 prior to the nucleotidyl transfer reaction. We also found that Ala substitutions at each of these four RB69 gp43 sites could incorporate dGDP as a substrate, although with markedly reduced efficiency compared to that with dGTP. In contrast in the parental exo- background, the K483A and Y567A substituted enzymes could not use dGDP as a substrate for primer extension. These results, taken together, are consistent with the putative roles of the four conserved residues in RB69 gp43 as stated above.

Alanine↗
PubMed1999

Tradescantia-micronucleus assay on the water quality of lake Hongzhe in Jiangsu Province, China.

Lake Hongzhe, located in the northwest part of the Province of Jiangsu, is one of the five largest freshwater lakes in China. It has great economic importance for the fishery industry and for scenic beauty. Effluents from the industrial development and runoff from farm chemicals have contributed increasingly to the water pollutants in recent years. For many years, water quality has been monitored only by chemical analysis. No information is provided from the chemical analysis on the toxicity level of the aquatic forms in the lake and the ecosystems that directly or indirectly depend upon this water. In the present study, some chemical components were determined from water samples collected from the lake and in addition, the genotoxicity of the same water samples was determined using the Tradescantia-micronucleus bioassay. Results confirmed that the quantity of pollutants in the water bears some relationship with the genotoxicity in terms of chromosome damage. High nitrates and nitrogen content were the main contributing factors observed. The use of bioassays such as the Tradescantia-micronucleus test together with chemical analyses to monitor the water quality is highly recommended for the general practice for the environmental monitoring stations through the country.

Biological Assay↗
PubMed1999

Cloning, expression and biochemical characterization of a basic-acidic hybrid phospholipase A2-II from Agkistrodon halys pallas.

A cDNA encoding a basic-acidic hybrid phospholipase A2-II from Agkistrodon halys Pallas with an N-terminus highly homologous to that of BPLA2 and a C-terminus sequence almost the same as that of APLA2 was inserted into a bacterial expression vector and effectively expressed in Escherichia coli RR1. The protein was produced as insoluble inclusion bodies. After partial purification by washing, the inclusion bodies with Triton X-100, denaturing and refolding, the renatured recombinant protein was purified by FPLC column superose 12. The purified recombinant enzyme with an isoelectric point of pH 6.8 could cross-react with antiserum prepared against acidic phospholipase A2. The enzymatic activity of the expressed basic-acidic hybrid phospholipase A2-II is close to that of denatured-refolded native basic phospholipase A2, and has the same inhibiting effect on platelet aggregation as denatured-refolded acidic phospholipase A2, but lacks the hemolytic activity of denatured-refolded basic phospholipase A2. To study the structural relationships among basic phospholipase A2, acidic phospholipase A2 and basic-acidic hybrid phospholipase A2-II, molecular modeling of basic-acidic hybrid phospholipase A2-II was done. The roles of various amino acid residues in the enzymatic activity and pharmacological activities of phospholipase A2 are discussed.

Agkistrodon↗
PubMed1999

Computer Simulation of the Aggregation and Sintering Restructuring of Fractal-like Clusters Containing Limited Numbers of Primary Particles.

A random particle computer simulation (in three dimensions) was conducted to investigate the structure and aggregation characteristics of small clusters (containing limited numbers of primary particles per cluster). Though an individual cluster of small size does not satisfy the power law, it was found that these aggregated clusters are fractal-like and comply with the fractal power law form in a statistical sense. This statistically averaged fractal dimension decreases as the clusters become smaller. A cluster-restructuring model is further developed to simulate the topological evolution of dendritic structured materials due to sintering at high temperatures. Results indicate that the cluster fractal dimension increases as sintering proceeds for small clusters, in contrast to results for large clusters wherein the topology is retained and the fractal dimension remains constant. A relationship of the fractal dimension change with the normalized surface area of dendrites for different-sized clusters is established. Copyright 1999 Academic Press.

Journal Article↗