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Biomedical subjects

X Zhao

Publications and source records attributed to X Zhao.

At least 415 records · Page 23Linked to original sources
PubMed1998

[Expression and prognostic relation of cathepsin D in non-small cell lung cancer tissues and lymph nodes].

OBJECTIVE: To study the expression and prognostic significance of cathepsin D(CD) in the patients with lung cancer. METHOD: A rapid immunohistochemical method (streptavidin-peroxidase conjugated method, SP) was used to detect CD expression of the NSCLC patients in 64 cases lung cancer tissues and paired lymph nodes samples. RESULT: The results showed positive expression rate of CD was 66% (42/64) in the lung cancer tissues, of which squamous cell cancer was 57% (17/30), adenocarcinoma was 74%(25/34). In the metastatic lymph nodes, the expression of CD was 57%(20/35). Expression of CD was higher in the patients with stage III-IV than in that with stage I-II (P < 0.05), of which was markedly higher in adenocarcinoma with lymph nodes metastasis than in which lymph nodes negative. CONCLUSION: Higher expression of CD is significantly related to the stage of the disease and lymph node metastasis in the adenocarcinoma. The expression of CD may be a good marker of prognosis in NSCLC.

Adenocarcinoma↗
PubMed1998

[The protective effect of captopril during myocardial ischemia and reperfusion and its mechanism].

OBJECTIVE: To investigate the myocardial protective effect of captopril (Cpl) during ischemia and reperfusion injury. METHODS: Sixteen mongrel dogs were randomly divided into the control and Cpl groups. In the control group, only modified St. Thomas cardioplegia was used. In the Cpl group, St. Thomas cardioplegia and reperfusional blood containing captopril 4.6 mumol/L were used. The plasma renin activity (RA), contents of angiotensin II (AT-II) and endothelin-1 (ET-1) in arterial blood were determined before cardiopulmonary bypass (CPB) and 5, 35, 60 min after reperfusion. The myocardial RA, contents of AT-II, ET-1 and malondyldialdehyde (MDA) were also measured. Parameters of cardiac function were monitored simultaneously. RESULTS: In the control group the plasma RA, AT-II and ET-1 contents were increased after reperfusion and significantly higher than those before CPB (P < 0.01). However, the content of AT-II in the Cpl group was not increased after reperfusion. The content of ET-1 in the Cpl group was increased but significantly lower than that in the control group (P < 0.01). The myocardial AT-II, ET-1 and MDA contents in the Cpl group were significantly lower than those in the control group. The cardiac index (CI) and coronary blood flow (CBF) in the Cpl group regained normal after reperfusion at 35 min. CONCLUSIONS: Cardioplegia and reperfusion blood containing 4.6 mumol/L captopril could ameliorate the cardiac performances by inhibiting myocardial and systemic RAS and decreasing the ET-1 production.

Angiotensin II↗
PubMed1998

[Treatment of simple obesity in children with photo-acupuncture].

OBJECTIVE: To study the treatment of simple obesity in children and observe its effect. METHODS: Two hundred and two patients were treated with self-produced photo-acupuncture apparatus (101 cases) or ear-pressing (101 cases), and their effects were observed and compared. RESULTS: Effects of both methods were satisfactory. The photo-acupuncture showed a better result than that of the ear-pressing. After treatment, the obesity indexes lowered significantly and levels of blood lipids, glucose, cortisol and triiodothyronine were all improved markedly. CONCLUSIONS: Photo-acupuncture is a safe, painless, nontraumatic and effective method for treatment of simple obesity, and it is easy to be accepted by children.

Acupressure↗
PubMed1998

[Protective effects of folium Ginkgo extract on experimental cerebral ischemia of mice].

Folium Ginkgo extract(EGb761) has been proved able to significantly prolong the survival time of mice suffering from cerebral ischemia induced by occluding bilateral common carotids, and reduce the inhibition of cerebral GSH-Px and Na(+)-K(+)-ATPase activities during reperfusion processes of these mice. Pretreatment with EGb761 also helps alleviate the subcellular damages in hippocampus of cerebral ischemic mice.

Animals↗
PubMed1998

[Identification of commercial Chinese medicine ziwan].

OBJECTIVE: Commercial samples of Ziwan have been investigated and identified to find out the original species in circulation. METHOD: Comparative histological and morphological identification. RESULT: The main original plant species are Aster tataricus, Ligularia fischeri, L. hodgsonii, L. intermedia, L. wilsoniana, L. sibirica var. araneosa, L. veitchiana and L. caloxantha. CONCLUSION: The root and rhizome of A. tataricus are used as Ziwan in most areas of China; but those of Ligularia species are used as Ziwan(named Shanziwan) in southwest, and part of northwest and northeast areas of China.

Asteraceae↗
PubMed1998

[Intracardiac operations performed in beating heart through mini-thoracotomy in 34 patients].

OBJECTIVE: To introduce the technique of intracardiac operations performed in beating heart through mini-thoracotomy. METHOD: >From March 1995 to June 1997, intracardiac operations were performed in beating heart through right subaxillary anterolateral mini-thoracotomy with normothermic extracorporeal circulation in 34 patients. 16 patients had atrial septal defect, 14 ventricular septal defect, 2 mitral insufficiency, 1 right coronary artery-right ventricular fistula, and 1 Ebstein's anomaly. RESULT: The mean cardiopulmonary bypass time was 22.54 minutes. There were no embolism, arrhythmia and cerebral complications. Postoperative hospital stay was 8.0 +/- 2.2 days. All the patients had no heart murmur and residual shunt, and enjoyed a full range of physical activities in a follow-up of 2 to 26 months. CONCLUSION: Intracardiac operations performed in beating heart through right subaxillary anterolateral mini-thoracotomy appears to be less invasive, simple, safe and cosmetic.

Adolescent↗
PubMed1998

[Effects of beta-endorphin on glutamate neurotoxicity].

The effects of beta-endorphin(beta-End) on monosodium glutamate(MSG) neurotoxicity were studied via morphological observation and image analysis of neuronal areas, together with the determination of intracellular free calcium concentration ([Ca2+]i) in single neuron and radioimmunoassay for beta-End contents. beta-End(1.0 mg.kg-1, s.c.) was found to obviously aggravate the neuronal injury in the arcuate nucleus of hypothalamus induced by MSG(0.5 g.kg-1, s.c.). Just as MSG increased [Ca2+]i significantly, beta-End(2.0 g.L-1) itself also increased it, though the extent of elevation was smaller than that of MSG(17.0 mg.L-1). The obvious changes of [Ca2+]i induced by both MSG and beta-End were partially reversed after pretreatment with verapamil. On the other hand, the content of beta-End in different areas of the brain were augmented following the addition of MSG and further elevated by morphine treatment. These findings suggest that the mechanisms of the enhancing effect of beta-End on glutamate neurotoxicity were linked to the aggravation on the disruption of intracellular Ca2+ homeostasis induced by MSG. Moreover, the fact that opioids promote beta-End release induced by MSG may be involved in the mechanisms as well.

Animals↗
PubMed1998

[Purification and properties of inulinases from Aspergillus niger M89].

Four inulinase components were purified from Aspergillus niger M89 by (NH4)2SO4 fractionation, Sephadex G-200 gel filtration, DEAE-cellulose chromatography and polyacrylamide gel electrophoresis (PAGE). The molecular weight of EI EII EIII and EIV were indicated to be 102.6, 97.9, 62.5 and 36.5 kD respectively by SDS-PAGE. Measured by isoeleetric focusing, their isoelectric points were 4.15, 4.24, 4.48 and 4.15 respectively. Four forms of inulinase exibited maximal inulinase activity between 55-60 degrees C with optimal pH 4.0-5.0. There were some difference in their thermal stability. The little the molecule of the component was, the stronger its thermal stability was. All of four components were exo-acting inulinases.

Aspergillus niger↗
PubMed1998

[Induction of antitumor immune response by NK-cell-sensitive target cells transfected by B7-1 gene].

OBJECTIVE: To investigate whether the expression of B7-1 is involved in NK cell activation. METHODS: B7-1 gene was transfected into K562 cell line (a sensitive target cell of NK cell, without MHC class I expression) by electropolation. Specific cytotoxicity of NK cells to B7+K562 cell was assayed by 4-h Cr release assay. The proliferation of NK cells induced by B7+K562 cell was analysed by Flow Cytometry. Expansion of NK cells and cloning of NK cells were performed by mixed lymphocyte-tumor cultures and limiting dilution analysis. Production of TNF-A, GM-CSF and IFN-A was detected by ELISA tests. RESULTS: The cytotoxicity of NK cells to B7+K562 cell could be induced and that the number of NK cells could be increased by stimulation with B7+K562 cells, in particular, further enhanced with biotherapeutic agent such as OK432 and IL-2. Also, NK cell clones were established. Cytokines such as TNF- A, INF- A and GM-CSF were detected in the supernatant produced by NK cell clones. In addition, culture of lymphocytes in the presence of supernatant produced by NK cell clones and tumor antigens resulted in an increased autologous tumor killing(ATK). CONCLUSION: These findings suggest that K562 cells transfected by B7-1 gene may elicit a series of antitumor immunity and these cells may be used for further development of therapeutic tumor vaccine.

B7-1 Antigen↗
PubMed1998

Ethanol inhibits the potentiation of endotoxin by dibutyryl cAMP and 2-methylthio ATP in vivo.

Ethanol (ETOH) selectively suppressed Escherichia coli endotoxin lipopolysaccharide (LPS)-stimulated, but not dibutyryl cAMP (db-cAMP)-stimulated upregulation of inducible nitric oxide synthase (iNOS) in rat alveolar macrophages (AMs) in vivo (Zhao et al., Alcohol. Clin. Exp. Res. 21:1062-1074, 1997). LPS-induced stimulation of iNOS is inhibited in vitro by db-cAMP and purine-2-Y (P2Y) receptor-mediated agonists. We examined the effect of ETOH on this interaction in rat lung AMs in vivo. Two hours after co-administration of LPS [0.6 mg/kg, intratracheal (i.t.)] with db-cAMP (0.1 mg/kg, i.t.) or 2-methylthio-adenosine-triphosphate (2-mes-ATP) to Sprague-Dawley rats (225 to 250 g) (n = 10 to 24/gp) iNOS messenger ribonucleic acid (mRNA), iNOS protein, and nitrate and nitrite anions [reactive nitrogen intermediates (RNIs)] in bronchoalveolar lavage fluid (BALf), and the ex vivo incubates of AMs were increased more than when these compounds were given individually to the rats. Co-administration of LPS with the autacoids did not affect LPS-stimulated increases of tumor necrosis factor-alpha (TNF alpha) mRNA, but inhibited LPS-stimulated BALf TNF alpha protein and attenuated LPS-mediated decreases of cell-associated TNF alpha. Pretreatment of rats with ETOH (4.5 g/kg, i.p.) or diethyidithiocarbamate (DETC; 5 mg/kg, i.t.), an inhibitor of the nuclear transcription factor NF kappa B (NF-kappaB), 30 min before co-administration of LPS with the autacoids restored iNOS mRNA levels to that obtained with the autacoid alone. Pretreatment of rats with ETOH decreased iNOS protein and RNI below that produced by either compound given individually to the rats. Although pretreatment of rats with DETC also decreased iNOS protein and RNI levels produced by LPS, the levels of both substances were elevated above that of the autacoid alone, LPS-induced upregulation of iNOS mRNA was associated with elevated levels of p65/p50 NF-kappaB in the nucleus of AMs. Neither db-cAMP or 2-mes-ATP affected LPS-stimulated NF-kappaB-DNA binding. Moreover, ETOH and DETC inhibited LPS-stimulated NF-kappaB-DNA binding. We conclude that in rat AMs in vivo: (1) both db-cAMP and P2Y-receptor stimulation summate with, rather than inhibit, LPS-induced upregulation of the iNOS mRNA, protein, and RNI; (2) ETOH and DETC inhibit LPS-induced upregulation of iNOS mRNA only when stimulated through the NF-kappaB pathway; and (3) ETOH inhibits both autacoid and LPS-stimulated formation of iNOS protein by a mechanism independent of its ability to suppress iNOS transcription.

Adenosine Triphosphate↗
PubMed1998

Interleukin 8 response by bovine mammary epithelial cells to lipopolysaccharide stimulation.

OBJECTIVE: To determine whether an established bovine mammary epithelial cell line expresses interleukin 8 (IL-8) mRNA and synthesizes antigenic IL-8 in response to lipopolysaccharide (LPS) stimulation. SAMPLE POPULATION: A bovine mammary epithelial cell line (MAC-T). PROCEDURE: mRNA was isolated from cells stimulated with graded concentrations of LPS. The first strand of IL-8 cDNA was synthesized, using a reverse transcriptase (RT) reaction with a specific oligonucleotide. Amplification of IL-8 cDNA was obtained by use of polymerase chain reaction (PCR). The MAC-T-derived antigenic IL-8 was quantified by use of a commercial anti-human IL-8 kit in a sandwich ELISA. RESULTS: RT-PCR revealed expression of MAC-T-derived mRNA within the first hour after stimulation with LPS. Expression of IL-8 mRNA was correlated to production of IL-8 protein detected in medium by use of the sandwich ELISA. Amounts of antigenic IL-8 increased in a dose- and time-dependent manner, and were maximal (57 pg/ml) at 48 hours after stimulation with 20 microg of LPS/ml. CONCLUSIONS: MAC-T cells secrete IL-8 in response to stimulation with LPS in a dose- and time- dependent manner. The results were consistent with our hypothesis that mammary gland epithelial cells can be a source of IL-8 during the early stage of mastitis. Therefore, IL-8 may have a pivotal role in resolving bacterial infections.

Animals↗
PubMed1997

Reaction mechanism of (6-4) photolyase.

The (6-4) photolyase catalyzes the photoreversal of the (6-4) dipyrimidine photoproducts induced in DNA by ultraviolet light. Using the cloned Drosophila melanogaster (6-4) photolyase gene, we overproduced and purified the recombinant enzyme. The binding and catalytic properties of the enzyme were investigated using natural substrates, T[6-4]T and T[6-4]C, and the Dewar isomer of (6-4) photoproduct and substrate analogs s5T[6-4]T/thietane, mes5T[6-4]T, and the N-methyl-3'T thietane analog of the oxetane intermediate. The enzyme binds to the natural substrates and to mes5T[6-4]T with high affinity (KD approximately 10(-9)-10(-10) M) and produces a DNase I footprint of about 20 base pairs around the photolesion. Several lines of evidence suggest that upon binding by the enzyme, the photoproduct flips out of the duplex. Of the four substrates that bind with high affinity to the enzyme, T[6-4]T and T[6-4]C are repaired with relatively high quantum yields compared with the Dewar isomer and the mes5T[6-4]T which are repaired with 300-400-fold lower quantum yield than the former two photoproducts. Reduction of the FAD cofactor with dithionite increases the quantum yield of repair. Taken together, the data are consistent with photoinduced electron transfer from reduced FAD to substrate, in a manner analogous to the cyclobutane pyrimidine dimer photolyase.

Animals↗
PubMed1997

DNA topoisomerase targets of the fluoroquinolones: a strategy for avoiding bacterial resistance.

Fluoroquinolones are antibacterial agents that attack DNA gyrase and topoisomerase IV on chromosomal DNA. The existence of two fluoroquinolone targets and stepwise accumulation of resistance suggested that new quinolones could be found that would require cells to obtain two topoisomerase mutations to display resistance. For wild-type cells to become resistant, the two mutations must be acquired concomitantly. That is expected to occur infrequently. To identify such compounds, fluoroquinolones were tested for the ability to kill a moderately resistant gyrase mutant. Compounds containing a C8-methoxyl group were particularly lethal, and incubation of wild-type cultures on agar containing C8-methoxyl fluoroquinolones produced no resistant mutant, whereas thousands arose during comparable treatment with control compounds lacking the C8 substituent. When the test strain contained a preexisting topoisomerase IV mutation, which by itself conferred no resistance, equally high numbers of resistant mutants were obtained for C8-methoxyl and control compounds. Thus C8-methoxyl fluoroquinolones required two mutations for expression of resistance. Although highly lethal, C8-methoxyl fluoroquinolones were not more effective than C8-H controls at blocking bacterial growth. Consequently, quinolone action involves two events, which we envision as formation of drug-enzyme-DNA complexes followed by release of lethal double-strand DNA breaks. Release of DNA breaks, which must occur less frequently than complex formation, is probably the process stimulated by the C8-methoxyl group. Understanding this stimulation should provide insight into intracellular quinolone action and contribute to development of fluoroquinolones that prevent selection of resistant bacteria.

Anti-Infective Agents↗
PubMed1997

Deletions of the Aequorea victoria green fluorescent protein define the minimal domain required for fluorescence.

The Green Fluorescent Protein (GFP) from the jellyfish Aequorea victoria is a widely used marker for gene expression and protein localization studies. Dissection of the structure of the protein would be expected to shed light on its potential applications to other fields such as the detection of protease activity. Using deletion analysis, we have defined the minimal domain in GFP required for fluorescence to amino acids 7-229. This domain starts at the middle of the first small alpha helix at the N terminus of GFP and ends immediately following the last beta sheet. Studies of the amino acids at both termini of the minimal domain revealed that positions 6 and 7 at the N terminus are Glu-specific. Change of the Glu residues to other amino acids results in reduction of GFP fluorescence. Position 229 at the C terminus of GFP, however, is nonspecific: the Ile can be replaced with other amino acids with no measurable loss of fluorescence. A total of only 15 terminal amino acids can be deleted from GFP without disrupting fluorescence, consistent with findings of a previous study of GFP crystal structure (Ormo, M., Cubitt, A. B., Kallio, K., Gross, L. A., Tsien, R. Y., Remington, S. J. (1996) Science 273, 1392-1395 and Yang, F., Moss, L. G., and Phillips, G. N., Jr. (1996) Nat. Biotechnol. 14, 1246-1251) that a tightly packed structure exists in the protein. We also generated internal deletions within the loop regions of GFP according to its crystal structure and found that all such deletions eliminated GFP fluorescence.

Animals↗
PubMed1997

Retinoblastoma protein-dependent growth signal conflict and caspase activity are required for protein kinase C-signaled apoptosis of prostate epithelial cells.

Both protein kinase C and the retinoblastoma tumor suppressor protein have been linked to the regulation of cell growth and cell death, suggesting the differential roles these factors play in mediating cell fate. In some cells, protein kinase C-induced activation of the retinoblastoma protein results in G1 arrest. However, inducible overexpression and activation of the protein kinase Calpha isozyme or the addition of 12-O-tetradecanoylphorbol-13-acetate in the prostate epithelial cell line, LNCaP, resulted in apoptosis preceded by induction of p21 and dephosphorylation of the retinoblastoma protein. Consistent with a role for the retinoblastoma growth suppressor protein in protein kinase C-induced apoptosis, DU145 cells, which do not express functional retinoblastoma protein or LNCaP cells, which have been transfected with the retinoblastoma inhibitor, E1a, were resistant to apoptosis. LNCaP apoptosis was initiated by a unique conflict between the growth-suppressive activity of the retinoblastoma protein and growth-promoting mitogenic signals. Thus, when this conflict was prevented by serum depletion, apoptosis was suppressed. The caspase family of cysteine proteases is believed to encompass the execution machinery of mammalian apoptosis, and addition of the cell-permeable caspase inhibitor, Z-Val-Ala-Asp-fluoromethylketone, afforded nearly total protection from protein kinase C-signaled apoptosis. This protection correlated with the total loss of caspase activity as measured by the proteolytic cleavage of nuclear poly(ADP-ribose) polymerase. On the basis of these results, we propose that protein kinase C regulates a novel cell death pathway that is initiated by a cellular conflict between retinoblastoma growth-suppressive signals and serum mitogenic signals in proliferating prostate epithelial cells and that is executed by the caspase family of cysteine proteases.

Adenovirus E1A Proteins↗
PubMed1997

Capillary electrophoresis methodology for identification of cancer related gene expression patterns of fluorescent differential display polymerase chain reaction.

The mRNA differential display technique is a method for molecular survey and analysis of differential gene expression in eukaryotic cells and tissues. We have previously described the use of ABI Prism fluorescent technology to specifically amplify expressed sequence tags (ESTs) from several different biological paradigms. High throughput, fluorescent differential display performed on an automated sequencer (ABI 377) has proven to have significant cost cutting and time saving attributes compared to that of the radioactive differential display. Additionally, fluorescent tagged mRNA specific reverse transcription and PCR decreases the number of the inherent artifacts associated with radioactive differential display. We report here the application of a capillary electrophoresis system (ABI 310) to the identification of fluorescent differential display generated EST patterns. RNA samples from human and animal breast cancer paradigms were exposed to this technique and analyzed by the ABI 310 and the ABI 377. GeneScan and Genotyper software applications were used for rapid and semi-automated characterization of fluorescently labeled ESTs. Automated sample loading and uniform sample electrophoresis are among the main advantages of this system which significantly increase the precision and reproducibility of fluorescent differential display.

Adenocarcinoma↗
PubMed1997

An scl gene product lacking the transactivation domain induces bony abnormalities and cooperates with LMO1 to generate T-cell malignancies in transgenic mice.

The product of the scl (also called tal-1 or TCL5) gene is a basic domain, helix-loop-helix (bHLH) transcription factor required for the development of hematopoietic cells. Additionally, scl gene disruption and dysregulation, by either chromosomal translocations or a site-specific interstitial deletion whereby 5' regulatory elements of the sil gene become juxtaposed to the body of the scl gene, is associated with T-cell acute lymphoblastic leukemia (ALL) and T-cell lymphoblastic lymphoma. Here we show that an inappropriately expressed scl protein, driven by sil regulatory elements, can cause aggressive T-cell malignancies in collaboration with a misexpressed LMO1 protein, thus recapitulating the situation seen in a subset of human T-cell ALL. Moreover, we show that inappropriately expressed scl can interfere with the development of other tissues derived from mesoderm. Lastly, we show that an scl construct lacking the scl transactivation domain collaborates with misexpressed LMO1, demonstrating that the scl transactivation domain is dispensable for oncogenesis, and supporting the hypothesis that the scl gene product exerts its oncogenic action through a dominant-negative mechanism.

Animals↗