Biomedical subjects

Z Gao

Publications and source records attributed to Z Gao.

At least 109 records · Page 6Linked to original sources

PubMed1999

[Simultaneous determination of molybdenum and chromium by artificial neural networks spectrophotometry].

In this paper, a three-layer artificial neural networks were applied to simultaneous determination of molybdenum and chromium by spectrophotometry. The apparent molar absorptivities of the complex of molybdenum and chromium are 1.4 x 10(5) L x mol(-1) x cm(-1) and 3.7 x 10(4) L x mol(-1) x cm(-1), respectively. A method has been developed for simultaneous determination of molybdenum and chromium in steel with satisfactory results. The paralysis in the procedure of training about ANN has been avoided with the improved back propagation algorithms. The simple transformation method for target vectors and criterion function convenient for selection of the parameters about the networks has been put foward.

English Abstract↗

PubMed1998

New Carbon-Silica Composite Adsorbents from Elutrilithe.

Carbon-silica composite adsorbents with high surface area and pore volume were prepared from natural elutrilithe. The elutrilithe was chemically activated with K2CO3 at 1123 K and then dissolved in water. The textural and adsorptive properties of the composite adsorbents can be adjusted by varying the pH and concentration of the sol mixture and the gel aging temperature. Composite adsorbents prepared at low concentration have high adsorption capacities for both water (43.4%) and cyclohexane (32.0%), exceeding those of ordinary commercial silica gel and active carbon. The adsorbents prepared at high concentration are more hydrophobic in nature, with adsorption capacities for water and cyclohexane of 18.5 and 41.5%, respectively. The composite adsorbents are resistant to repetitive adsorption and regeneration cycles. Copyright 1998 Academic Press.

Journal Article↗

PubMed1998

A study of sexual behavior among rural residents of China.

OBJECTIVE: Although the recent spread of HIV/AIDS and other sexually transmitted diseases (STDs) in China has been associated with sexual activities, little information has been available about sexual behavior in rural areas with high HIV prevalence. Studies identifying high-risk sexual behaviors are needed to formulate effective prevention programs. METHODS: A cross-sectional study design was used to measure sexual activities using a two-stage cluster sampling method. A two-part anonymous questionnaire was used. Sensitive questions related to sexual behavior were administered using a tape recorder, earphones, and an answer sheet which did not include the text. RESULTS: In total, 1057 subjects were interviewed. Among 886 sexually active individuals, 7.8% had >1 sexual partner, 22.8% had premarital sex, 2.4% had anal intercourse, 4.1% had oral intercourse, and 2.3% had both anal and oral intercourse. Less than 2% reported past or current sexually transmitted diseases. Overall, 10.4% used condoms; only 11.2% for every sexual act. History of premarital and extramarital sex was higher in younger people. CONCLUSIONS: Sexual norms in rural China are changing rapidly and high-risk sexual behavior among young rural residents is increasing. Strategies to prevent HIV/AIDS should include education to promote delayed onset of sexual activity, safer sexual behavior, and condom use.

Adolescent↗

PubMed1998

Species diversity in the structure of zonadhesin, a sperm-specific membrane protein containing multiple cell adhesion molecule-like domains.

A hallmark of gamete interactions at fertilization is relative or absolute species specificity. A pig sperm protein that binds to the extracellular matrix of the egg in a species-specific manner was recently identified and named zonadhesin (Hardy, D. M., and Garbers, D. L. (1995) J. Biol. Chem. 270, 26025-26028). We have now cloned a cDNA for mouse zonadhesin (16.4 kb), and it demonstrates a large species variation in the numbers and arrangements of domains. Expression of mouse zonadhesin mRNA is evident only within the testis, and the protein is found exclusively on the apical region of the sperm head. There are 20 partial D-domains, found as tandem repeats, inserted between two of the four full D-domains and an additional partial D-domain. These domains are homologous to the D-domains of von Willebrand factor and alpha-tectorin. A region at the N terminus of the mouse cDNA contains three tandem repeats homologous to MAM domains. These are domains comprised of about 160 amino acids that are present in transmembrane proteins such as the meprins and receptor protein-tyrosine phosphatases, where they appear to function in cell/cell interactions. Additionally, mouse zonadhesin contains a mucin-like domain and a domain homologous to epidermal growth factor (EGF). A putative single transmembrane segment separates a short carboxyl tail from the extracellular region. The existence of MAM, mucin, D-, and EGF domains suggest that mouse zonadhesin functions in multiple cell adhesion processes, where binding to the extracellular matrix of the egg is but one of the functions of this sperm-specific membrane protein.

Amino Acid Sequence↗

PubMed1998

Study on a fluorescence-enhanced system of 1,2,4-trihydroxyanthroquinone-Be(2+)-DNA.

Fluorescence-enhancement of 1,2,4-trihydroxyanthroquinone (THAQ)-Be2+ complex enhanced by nucleic acid was studied. Experimental results revealed that double-stranded DNA can enhance remarkably the fluorescence intensity of THAQ-Be2+, while RNA cannot. Based on these results, a fluorescence method for the selective determination of DNA in the presence of RNA was developed. Maximum fluorescence intensity was found in the pH range 3.6-4.5 with maximum excitation and emission wavelengths at 510 and 565 nm, respectively. Under optimum conditions, the calibration graph was linear over the range 0.08-18 micrograms ml-1 for double-stranded fish sperm DNA (fsDNA) with the detection limit being 2.75 x 10(-8) g ml-1. The method was applied for the determination of DNA in synthetic samples. The relative S.D. for five replicates was within 4%. In addition, the interaction mechanism of THAQ-Be2+ with DNA was also discussed.

Anthraquinones↗

PubMed1998

Mice lacking neutrophil elastase reveal impaired host defense against gram negative bacterial sepsis.

Neutrophil elastase (NE) is a potent serine proteinase whose expression is limited to a narrow window during myeloid development. In neutrophils, NE is stored in azurophil granules along with other serine proteinases (cathepsin G, proteinase 3 and azurocidin) at concentrations exceeding 5 mM. As a result of its capacity to efficiently degrade extracellular matrix, NE has been implicated in a variety of destructive diseases. Indeed, while much interest has focused on the pathologic effects of this enzyme, little is known regarding its normal physiologic function(s). Because previous in vitro data have shown that NE exhibits antibacterial activity, we investigated the role of NE in host defense against bacteria. Generating strains of mice deficient in NE (NE-/-) by targeted mutagenesis, we show that NE-/- mice are more susceptible than their normal littermates to sepsis and death following intraperitoneal infection with Gram negative (Klebsiella pneumoniae and Escherichia coli) but not Gram positive (Staphylococcus aureus) bacteria. Our data indicate that neutrophils migrate normally to sites of infection in the absence of NE, but that NE is required for maximal intracellular killing of Gram negative bacteria by neutrophils.

Animals↗

PubMed1998

Phagocytic and tumor necrosis factor alpha response of human mast cells following exposure to gram-negative and gram-positive bacteria.

Recent studies have implicated rodent mast cells in the innate immune response to infectious bacteria. We report that cord blood-derived human mast cells (CBHMC) obtained from culture of cord blood progenitors phagocytozed and killed various gram-negative and gram-positive bacteria and simultaneously released considerable amounts of tumor necrosis factor alpha. Overall, the extent of the endocytic and exocytic response of CBHMC correlated with the number of adherent bacteria. Thus, human mast cells are intrinsically capable of mediating microbial recognition and of actively contributing to the host defense against bacteria.

Gram-Negative Bacteria↗

PubMed1998

The Epstein-Barr virus lytic transactivator Zta interacts with the helicase-primase replication proteins.

The Epstein-Barr virus transactivator Zta triggers lytic gene expression and is essential for replication of the lytic origin, oriLyt. Previous analysis indicated that the Zta activation domain contributed a replication-specific function. We now show that the Zta activation domain interacts with components of the EBV helicase-primase complex. The three helicase-primase proteins BBLF4 (helicase), BSLF1 (primase), and BBLF2/3 (primase-associated factor) were expressed fused to the Myc epitope. When expression plasmids for BBLF4 or BBLF2/3 plus BSLF1 (primase subcomplex) were separately transfected, the proteins localized to the cytoplasm. Interaction between Zta and the components of the helicase-primase complex was tested by examining the ability of Zta to alter the intracellular localization of these proteins. Cotransfection of Zta with Myc-BBLF4 resulted in nuclear translocation of Myc-BBLF4; similarly, cotransfection of Zta with the primase subcomplex led to nuclear translocation of the Myc-BSLF1 and Myc-BBLF2/3 proteins. This relocalization provides evidence for an interaction between Zta and the helicase and Zta and the primase subcomplex. An affinity assay using glutathione S-transferase-Zta fusion proteins demonstrated that Myc-BBLF4 and Myc-BBLF2/3 plus BSLF1 bound to the Zta activation domain (amino acids 1 to 133). In the nuclear relocalization assay, the amino-terminal 25 amino acids of Zta were required for efficient interaction with the primase subcomplex but not for interaction with BBLF4. Evidence for interaction between oriLyt bound Zta and the helicase-primase complex was obtained in a superactivation assay using an oriLyt-chloramphenicol acetyltransferase (CAT) reporter. Zta activated expression from a CAT reporter containing the complete oriLyt region and regulated by the oriLyt BHLF1 promoter. Cotransfection of the helicase-primase proteins, one of which was fused to a heterologous activation domain, led to Zta-dependent superactivation of CAT expression. This assay also provided evidence for an interaction between the single-stranded DNA binding protein, BALF2, and the Zta-tethered helicase-primase complex. The helicase-primase interaction is consistent with a role for Zta in stabilizing the formation of an origin-bound replication complex.

Animals↗

PubMed1998

Mta has properties of an RNA export protein and increases cytoplasmic accumulation of Epstein-Barr virus replication gene mRNA.

The Epstein-Barr virus (EBV) Zta and Mta regulatory proteins were previously found to be required for efficient replication of oriLyt in cotransfection-replication assays, but the contribution of Mta to the replication process was unknown. We now demonstrate that Mta regulates replication gene expression. Using the polymerase processivity factor BMRF1 as an example, we found that in transfected cells, total BMRF1 mRNA levels were unaffected by Mta but that the amounts of cytoplasmic BMRF1 RNA and protein were greatly increased in the presence of Mta. Mta also increased cytoplasmic accumulation of the BALF2, BALF5, BSLF1, and BBLF4 replication gene mRNAs but did not affect cytoplasmic levels of BBLF2/3 mRNA. Thus, five of the six core replication genes require Mta for efficient accumulation of cytoplasmic RNA. The contribution of Mta to posttranscriptional RNA processing was examined. Examination of Mta localization in transfected cells by indirect immunofluorescence revealed that Mta colocalized with the splicing factor SC35. We also found that Mta has RNA binding activity. Glutathione S-transferase-Mta bound to BMRF1 and BMLF1 transcripts but not to a control cellular gene RNA. Mta contains a consensus leucine-rich nuclear export signal. Such signal sequences are characteristic of proteins that undergo nuclear export. Examination of Mta localization in a heterokaryon assay provided evidence that Mta shuttles between the nucleus and the cytoplasm. Our experiments indicate that Mta functions in RNA processing and transport and mediates cytoplasmic accumulation of a number of EBV early mRNAs.

Amino Acid Sequence↗

PubMed1998

Overexpression of the Na+,K+-ATPase alpha1 subunit increases Na+,K+-ATPase function in A549 cells.

We hypothesized that viral mediated transfer of Na+,K+-ATPase subunit genes to alveolar epithelial cells to overexpress Na+, K+-ATPase could increase Na+,K+-ATPase function. We produced replication-deficient human type 5 adenoviruses that contained cytomegalovirus (CMV)-driven cDNAs for the rat alpha1 and beta1 subunits of Na+,K+-ATPase (AdMRCMValpha1 and AdMRCMVbeta1, respectively). These viruses were used to transduce human adenocarcinoma cells (A549) in culture. Na+,K+-ATPase function was increased by 2.5-fold in the AdMRCMValpha1-infected cells. Sham and AdMRCMVbeta1-infected cells, and cells infected by a CMV-driven beta-galactosidase-expressing adenovirus, had no increases in Na+, K+-ATPase activity. A549 cells infected with multiplicities of infection of 10-200 of AdMRCMValpha1 demonstrated expression of a rat alpha1 mRNA and increased alpha1 protein; no change in beta1 message or protein was noted. Ouabain sensitivity was measured in A549 cells following infection with AdMRCMValpha1. In contrast to controls, AdMRCMValpha1-infected cells demonstrated two IC50s. The first was similar to the IC50s of the controls; the second IC50 was 2 logs greater than the first, consistent with the presence of both the rat and human alpha1 isozymes. These results demonstrate for the first time that adenoviruses can be used to augment Na+,K+-ATPase function.

Adenocarcinoma↗

PubMed1998

[An experimental study on effects of antimony on anti-oxidase system on liver mitochondria in mice].

OBJECTIVE: To explore the mechanisms of toxic liver damage caused by antimony. METHODS: Experimental mice were injected peritoneally 40 mg/kg of antimony trioxide daily for 28 days to observe the effects of it on the anti-oxidase system in their liver mitochondria. RESULTS: Activities of aspartate aminotransferase and alanine aminotransferase increased obviously in the experimental animals, and those of superoxide dismutase and glutathione peroxidase in liver mitochondria lowered, as compared to those in the control animals with statistical significance. Content of malonyl dialdehyde in the liver mitochondria was 47.27 +/- 1.21 mumol/L in the experimental animals, significantly higher than that in controls. CONCLUSION: It suggested that the mechanism of liver damage caused by antimony associated with injury to the ability of anti-oxidation and lipid peroxidation in the liver mitochondria.

Animals↗

PubMed1998

[Research on detection of type C2 staphylococcus enterotoxin in food with piezoelectric immunosensors].

Using the biosensor of immobilization of antibody by Piezoectric Immunosensors (PEI) method, the concentration of antigen was determined. When the concentration of antigen was 10 micrograms/L-2 mg/L, the linear response was found. When the sensor was applied to detect type C2 staphylococcus enterotoxin in food, the method was proved with high specificity and selectivity.

Enterotoxins↗

PubMed1998

[Antisense oligodeoxynucleotide of TGF alpha inhibits its gene expression and proliferation of a human glioma cell line].

OBJECTIVE: To study the effect of antisense oligodeoxynucleotide(ON) of TGF alpha on its gene expression in TJ 905 cell line. METHODS: Antisense and sense TGF alpha phosphorothioate ON (SON) and random SON were synthesized and transfected to TJ 905 cells mediated by lipofectin. Their effects on the TGF alpha gene expression were examined by in situ hybridization of TGF alpha mRNA, immunohistochemical study and cell count. RESULTS: (1) TGF alpha antisense SON could significantly inhibit the growth of TJ 905 cell line. The inhibition peaked at 24 hour after transfection, the inhibition rate reached 68% at 20 microM, and the effect decreased 72 hours after transfection. The inhibition effect was dose dependent. (2) Antisense TGF alpha SON inhibited TGF alpha expressions at both mRNA and protein levels. CONCLUSION: Antisense TGF alpha SON can inhibit the expressions of TGF alpha and markedly inhibit cell growth of human glioma TJ 905 cell line. TGF alpha contributes in the growth potential of glioma.

Brain Neoplasms↗

PubMed1998

[A pathological study on the autotransplantation of monkey's cervical sympathetic ganglion into brain for the treatment of Parkinson's disease].

OBJECTIVE: In order to find out evidences in explicating whether the transplanted ganglion cells can be kept surviving longer in the brain and to find out an ideal transplantation way for the surgical treatment of Parkinson's disease. METHODS: Cervical sympathetic ganglions autotransplantation into the caudate nuclei of the brain in 9 rhesus monkeys known to have the symptoms and signs of the Parkinson's disease beforehand induced by using 1-methy1-4-phen-1, 2, 3, 6-tetrahydropynidne (MPTP) and in addition, muscle tendon tissue was also grafted for comparison. The experimental animals were followed up for 2 years. All the specimens taken were processed and prepared in continuous frozen sections for H & E, glyoxlyic acid induced dopamine fluorescence and immunochemistry stainings including anti-chromogranin A, synaptophysin, neurofilament, NSE, GFAP as markers. RESULTS: Two years after the autotransplantation operation, there were still surviving ganglion cells left in the caudate nuclei. The grafted ganglion cells were connected by the neurodendrites with the brain tissue which showed dopamine fluorescence positive and also had expression of chromogramin A, synaptophysin and neurofilaments. CONCLUSIONS: The grafted cells survived in the brain over 2 years. It's considered that the sympathetic ganglion is the first choice in comparing with other tissues as the graft for the surgical treatment of Parkinson's disease. Continuous frozen sections accompanying with inducing fluorescence and immunohistochemistry staining are seemed reliable as the parameters in checking the result after neural transplantation.

Animals↗

PubMed1998

[Investigation of the clinicopathologic features, immunophenotype and Epstein-Barr virus infection of the upper respiratory tract lymphomas in patients].

OBJECTIVE: To study the clinicopathologic features, immunophenotype and Epstein-Barr virus (EBV) infection of the upper respiratory tract lymphomas in patients from north China. METHODS: 112 cases of upper respiratory tract lymphomas in patients from north China were investigated. HE stain for histologic features. Immunohistochemistry studies were performed using monoclonal antibodies, UCHL-1 for T-lymphocyte, L26 and 4KB5 for B lymphocyte, CS1-4 for latent membrane protein-1 (LMP-1). In situ hybridization for EBV encoded small nuclear RNA (EBER 1/2, Y017, DAKO). RESULTS: 77/112 cases (68.75%) were T-cell lymphomas, 35 cases (31.25%) were B cell lymphomas. EBV-EBER 1/2 in situ hybridization positive in 54/101 (53.46%) cases, including 48 T-cell lymphoma cases and 6 B-cell lymphoma cases. CONCLUSION: Most upper respiratory tract lymphoma cases in patients from north China are T-cell lymphomas and are strongly associated with EBV.

Adolescent↗

PubMed1998

[A study of p16 gene and its protein expression in rhabdomyosarcoma].

OBJECTIVE: To evaluate the relationship between alteration of p16 gene, its protein expression and the pathogenesis and development of rhabdomyosarcoma (RMS). METHODS: 44 cases of RMS were examined for alteration of p16 gene with PCR-SSCP and 47 cases of RMS were examined for p16 protein expression with immunohistochemical method. RESULTS: The homozygous deletion of p16 gene was observed in 2 cases and mutations in 6 cases. Of these 8 cases with altered p16 gene, 6 had extensive invasion, recurrence or metastasis. The total negative rate of p16 protein expression in RMS was 38.3% (18/47 cases). Of these 8 cases with alterations of p16 gene, negative expression for p16 protein was observed in 7 cases and positive in only 1 cases. In contrast, no structural abnormalities of the p16 gene were detected in another 11 cases with negative expression of p16 protein. Higher rates of p16 gene abnormality and loss of p16 protein were observed in ARMS than in ERMS. Higher rate of extensive invasion, recurrence or metastasis was also found in the group negative for p16 protein. CONCLUSION: The abnormalities of p16 gene and loss of p16 protein expression may be related to the pathogenesis and development of some RMS.

Cyclin-Dependent Kinase Inhibitor p16↗

PubMed1998

[The preparation of chiral column of cellulose triacetate coated on small pore silica gel and the separation of enantiomers].

The cellulose triacetate (CTA) prepared by heterogeneous acetylation and coated on small pore 3-aminopropyl silica gel (10 nm) was used as chiral stationary phase for HPLC (OA column). The racemes of three drugs, two fulvenes and one dazine, were separated on this column. Among these racemes, timolol maleas was separated using 1.0 mol/L NaClO4:95% ethanol = 10:90 as mobile phase. Without NaClO4 in mobile phase, the resolution of timolol maleas can not occur. Ethanols of 95%-98% were used as mobile phase for other racemes. The influence of the content of water in mobile phase on the chiral separation of praziquentelum, the retention time and separation factor (alpha) were reduced with the increase of water content in mobile phase. When the content of water in the mobile phase was 13%, praziquentelum could not be separated. It was found that in the case of samples No. 1 and No. 2, when the substituents R1 and R2 or R'1 and R'2 of fulvenes are 4-methoxybenzoyl and 4-methoxyphenyl, the chiral separations of fulvenes can be obtained. For sample No. 4 when R1 and R2 of fulvenes are 2-methylbenzoyl and 2-methylphenyl or in the case of No. 5, when R1 and R2 are 5-bromo-2-furoyl and 5-bromo-2-furan, the chiral separations of fulvenes can not be achieved. For sample No. 6 and No. 7, when R'1 are 4-chlorobenzoyl and benzoyl or R'2 are 4-chlorophenyl and phenyl, the chiral separation also can not be achieved. The column performance and separation factor were not obviously reduced after used for four months.

Cellulose↗

PubMed1998

[The role of glucocorticosteroid and theophylline in asthmatic inflammation of murine model and the inhibition in NO production in lung].

OBJECTIVE: To investigate the role of glucocorticosteroid and theophylline in treatment of asthmatic inflammation and their effects in production of nitric oxide (NO) and the expression of inducible nitric oxide synthase (iNOS). METHOD: A murine model was set up (A group: asthma model, N group: control mice), then the number of WBC, eosinophils% (EOS), total protein level and the NO level in brochoalveolar lavage fluid (BALF) were measured after treatment with glucocorticosteroid (C1 group: dexamethason inhalation; C2 group: dexamethason peritoneal injection and C3 group: budisonide inhalation) and aminophylline(T group). The expression of iNOS was studied by histochemistry and immunohistochemistry. RESULT: There was a significant increase in number of WBC [(10.64 +/- 0.75) x 10(7)/L vs (3.15 +/- 0.92) x 10(7)/L, P < 0.001), EOS% (12.55% +/- 7.64% vs 0.02% +/- 0.04%, P < 0.001), total protein level (0.124 +/- 0.080 g/L vs 0.008 +/- 0.004 g/L, P < 0.001) and concentration of NO (5.00 +/- 1.87 mumol/L vs 1.30 +/- 0.67 mumol/L, P < 0.001) in BALF after antigen challenge, and the expression of iNOS was increased in airway epithelial cells and alveolar macrophages. After administration of steroids and theophylline, the number of WBC[C1: (5.05 +/- 1.14) x 10(7)/L, C2: (5.47 +/- 0.59) x 10(7)/L, C3: (6.53 +/- 0.47) x 10(7)/L, T: (3.65% +/- 1.04) x 10(7)/L, P < 0.001], EOS% (C1: 0.10% +/- 0.06%, C2: 0.10% +/- 0.08%, C3: 0.24% +/- 0.33%, T: 2.84% +/- 1.90%, P < 0.001-0.005), total protein level (C1: 0.016 +/- 0.011 g/L, C2: 0.010 +/- 0.008 g/L, C3: 0.020 +/- 0.012 g/L, T: 0.012 +/- 0.008 g/L, P < 0.001-0.05) were significantly decreased. There was a significant reduction of NO level (C1: 1.20 +/- 0.97 mumol/L, P < 0.001) and iNOS expression after treated with steroids, but no significant change after management with theophylline. CONCLUSION: EOS is main inflammatory cell in asthma. NO may play an important role in aggravating asthma. Steroids and theophylline both can inhibit cell infiltration and serum protein leakage in asthma. Steroids can also inhibit the production of NO and iNOS expression. But theophylline has no significant effect in NO.

Animals↗