Biomedical subjects

B Zhao

Publications and source records attributed to B Zhao.

At least 91 records · Page 5Linked to original sources

PubMed2000

Epstein-barr virus nuclear antigen 3C activates the latent membrane protein 1 promoter in the presence of Epstein-Barr virus nuclear antigen 2 through sequences encompassing an spi-1/Spi-B binding site.

The Epstein-Barr virus (EBV) nuclear antigen 3C (EBNA-3C) protein is a transcriptional regulator of viral and cellular genes that is essential for EBV-mediated immortalization of B lymphocytes in vitro. EBNA-3C can inhibit transcription through an association with the cellular DNA-binding protein Jkappa, a function shared by EBNA-3A and EBNA-3B. Here, we report a mechanism by which EBNA-3C can activate transcription from the EBV latent membrane protein 1 (LMP-1) promoter in conjunction with EBNA-2. Jkappa DNA-binding sites were not required for this activation, and a mutant EBNA-3C protein unable to bind Jkappa activated transcription as efficiently as wild-type EBNA-3C, indicating that EBNA-3C can regulate transcription through a mechanism that is independent of Jkappa. Furthermore, activation of the LMP-1 promoter is a unique function of EBNA-3C, not shared by EBNA-3A and EBNA-3B. The DNA element through which EBNA-3C activates the LMP-1 promoter includes a Spi-1/Spi-B binding site, previously characterized as an important EBNA-2 response element. Although this element has considerable homology to mouse immunoglobulin light chain promoter sequences to which the mouse homologue of Spi-1 binds with its dimerization partner IRF4, we demonstrate that the IRF4-like binding sites in the LMP-1 promoter do not play a role in EBNA-3C-mediated activation. Both EBNA-2 and EBNA-3C were required for transcription mediated through a 41-bp region of the LMP-1 promoter encompassing the Spi binding site. However, EBNA-3C had no effect on transcription mediated in conjunction with the EBNA-2 activation domain fused to the GAL4 DNA-binding domain, suggesting that it does not function as an adapter between EBNA-2 and the cellular transcriptional machinery. Like EBNA-2, EBNA-3C bound directly to both Spi-1 and Spi-B in vitro. This interaction was mediated by a region of EBNA-3C encompassing a likely basic leucine zipper (bZIP) domain and the ets domain of Spi-1 or Spi-B, reminiscent of interactions between bZIP and ets domains of other transcription factors that result in their targeting to DNA. There are many examples of regulation of the hematopoietic-specific Spi transcription factors through protein-protein interactions, and a similar regulation by EBNA-3C, in conjunction with EBNA-2, is likely to be an important and unique contribution of EBNA-3C to EBV-mediated immortalization.

Binding Sites↗

PubMed2000

Small pulmonary nodules: volumetrically determined growth rates based on CT evaluation.

PURPOSE: To determine the accuracy of high-resolution computed tomographic (CT) volumetric measurements of small pulmonary nodules to assess growth and malignancy status. MATERIALS AND METHODS: The accuracy of three-dimensional (3D) image extraction and isotropic resampling techniques was assessed by performing three experiments. The first experiment measured volumes in spherical synthetic nodules of two diameters (3.20 and 3.96 mm), the second measured deformable silicone synthetic nodules prior to and after their shape had been altered markedly, and the third measured nodules of various shapes and sizes. Three-dimensional techniques were used to assess growth in 13 patients for whom the final diagnosis was known and whose initial nodule diameters were less than 10 mm. By using the exponential growth model and the calculated nodule volume at two points in time, the doubling time for each subject was calculated. RESULTS: The three synthetic nodule studies revealed that the volume could be measured accurately to within +/-3%. All five malignant nodules grew, and all had doubling times less than 177 days. Some malignant nodules had asymmetric patterns of growth identified by using the 3D techniques but not the two-dimensional methods. All eight benign nodules had doubling times of 396 days or greater or showed a decrease in volume. CONCLUSION: CT volumetric measurements are highly accurate for determining volume and are useful in assessing growth of small nodules and calculating their doubling times.

Aged↗

PubMed2000

Production and interaction of oxygen and nitric oxide free radicals in PMA stimulated macrophages during the respiratory burst.

The activity of nitric oxide synthase (NOS) during the respiratory burst in phorbol-1,2-myristate-1,3-acetate (PMA) stimulated macrophages has been the topic of much debate in the literature. To help clarify the role of NOS, we have examined the chemiluminescence arising from peroxynitrite production, nitrite/nitrate and nitric oxide production, and oxygen consumption during the respiratory burst in PMA-stimulated macrophages. The Griess reaction was used to measure nitrite/nitrate, spin trapping with N-methyl D-glucamine dithiocarbamate (MGD)2-Fe2+ was used to quantify nitric oxide, and the spin probe 2,2,6,6-tetramethylpiperidine-N-oxyl-4-ol (TEMPOL) was used to measure oxygen consumption. Oxygen free radical production (hydroxyl and superoxide free radicals) was also investigated using the spin trap 5,5-dimethyl-1-pyroline-1-oxide (DMPO). The chemiluminescence emitted by the PMA-stimulated macrophages and nitrite/nitrate in the culture system were both found to increase. However, the rate of nitric oxide release remained constant, indicating that the activity of NOS is not enhanced during the respiratory burst in PMA stimulated macrophages.

Animals↗

PubMed2000

Angiotensin-converting enzyme gene insertion/deletion (I/D) polymorphism in hypertensive patients with different degrees of obstructive sleep apnea.

To investigate the role of the angiotensin-converting enzyme gene (ACE) insertion (I)/deletion (D) polymorphism in hypertensive patients with different degrees of obstructive sleep apnea (OSA). A case-control study was performed. One hundred seventy four Chinese subjects were divided into four groups depending on the severity of OSA as follows: 1) normal control group (NC, n=68), 2) isolated hypertension group (HT, n=45), 3) hypertensive patients with mild OSA group (MO, n=27), and 4) hypertensive patients with moderate to severe OSA group (MSO, n=34). The distribution of ACE gene I/D allele and genotypes were analyzed in the subject population, as was an OSA pedigree. The study showed that the frequency of ACE gene I/D polymorphism differed significantly among the four groups. The frequency of I allele and II genotype were significantly higher in the MSO group than in the other groups (p<0.05). The distribution of I allele and II genotype showed no significant difference between any of the other groups (p>0.05, respectively). Meanwhile the higher frequency of I allele and II genotype was observed in the OSA pedigree. The higher frequency of ACE gene I allele and II genotype were closely associated with the hypertensive patients with MSO. The inherited factors played an important role in the pathogenesis of hypertensive patients with MSO.

Adult↗

PubMed2000

[Introduction of wide spectrum rice bacterial blight resistance gene Xa21 into two-line genic male sterile rice variety Pei'ai 64S].

Agrobacterium-mediated transformation of two-line genic male sterile Indica rice variety Pei'ai 64S was conducted using a cloned gene, Xa21, as the foreign gene and mature embryo calli as the recipients. A total of 46 transgenic plants had been obtained. The PCR analysis and Southern blotting showed the integration of Xa21 gene into the genome the transgenic plants. Results of inoculation with philippine race 6 of Xanthomonas oryzae pv. oryzae indicated that most of transgenic plants obtained high resistance to rice bacterial blight disease (Xoo). Analyses of T1 plants of the tested transgenic lines showed that integrated Xa21 gene could be steadily inherited and segregated in a 3:1 ratio.

Oryza↗

PubMed2000

[Study on mRNA differential display in Mycobacterium tuberculosis H37Rv and H37Ra].

OBJECTIVE: To study genetic differences between H37Rv and H37Ra by mRNA differential display, paving the way for obtaining virulence-related gene of Mycobacterium tuberculosis (MTB). METHODS: Total RNA was extracted from MTB H37Rv and H37Ra, mRNA differential display was conducted following reverse transcription, polymerase chain reaction, polyacrilamide gel electrophoresis and radiography. The differential bands were recovered, reamplified, sequenced, and then homologous query was done. RESULTS: 10 differential bands between H37Rv and H37Ra were recovered, 2 of which were homologous to H37Rv DNA after query from NCBI database of GenBank. CONCLUSIONS: mRNA differential display is an effective, sensitive method, can display differences between different strains intra- and extra-species and be used in searching Mycobacterium tuberculosis virulence-related gene. Obtained differential bands in this study may cover MTB virulence-related gene.

Animals↗

PubMed2000

[Effect of Sindbis XJ-160 virus structural proteins on BHK-21 cell].

OBJECTIVE: To study the effect of Sindbis XJ-160 virus structural proteins on BHK-21 cell. METHODS: We constructed the expressing vector pcDNA3.1 ABC that contains the XJ-160 virus structural protein gene and then transfected it to BHK-21 cell. RESULTS: The expressed products can be detected by RNA dot blot hybridization or immUnofluorescent assay. The cytopathic effect was observed in BHK-21 cells transfected with pcDNA3.1 ABC. There was also condensed chromatin found accumulated. BHK-21 cell death and marked cell cycle changes were observed. CONCLUSIONS: These results indicate that cell apoptosis might be one of the mechanisms inducing cell death by XJ - 160 virus and its structural protein gene probably plays a role in this programmed cell death.

Apoptosis↗

PubMed2000

[The mechanism responsible for alleviation of hypoxic pulmonary vascular structural remodeling by L-arginine].

OBJECTIVE: To explore the mechanism of the therapeutic effect of L-arginine on hypoxic pulmonary vascular structural remodeling. METHODS: Eighteen age- and body weight-matched Wistar rats were randomly divided into hypoxic group, hypoxic with L-arginine group or control group. Pulmonary artery mean pressure (mPAP) of each rat was evaluated using right cardiac catheterization. Pulmonary vascular microstructure was measured and the ultrastructural changes in intra-acinar pulmonary muscularized arteries were observed. Meanwhile, indirect plasma concentration of nitric oxide (NO) was measured via spectrophotometry, and endothelin-1 (ET-1) mRNA expression in pulmonary artery endothelial cells was detected using in situ hybridization with a cRNA probe for ET-1. RESULTS: mPAP was significantly increased in hypoxic rats (2.71 kPa +/- 0.29 kPa) as compared with that of normal controls (2.05 kPa +/- 0.14 kPa) (P < 0.05). Microstructure and ultrastructure of pulmonary arteries changed obviously in hypoxic rats with the development of hypoxic pulmonary vascular structural remodeling. Meanwhile, indirect plasma NO concentration in hypoxic rats (3.54 micromol/L +/- 0.47 micromol/L) was markedly decreased compared with controls (4.79 micromol/L +/- 0.17 micromol/L) (P < 0.05). The expression of ET-1 mRNA of hypoxic rats strengthened obviously. However, mPAP was significantly decreased in hypoxic rats treated with L-arginine (2.23 kPa +/- 0.18 kPa) as compared with that of hypoxic rats (2.71 kPa +/- 0.29 kPa) (P < 0.05). L-arginine ameliorated pulmonary vascular structural remodeling of hypoxic rats in association with an increase in indirect plasma NO concentration (P < 0.05) and an inhibited ET-1 mRNA expression. CONCLUSION: L-arginine plays an important role in the regulation of development of hypoxic pulmonary vascular remodeling and hypoxic pulmonary hypertension, promoting NO production and inhibiting ET-1 mRNA expression in hypoxic rats.

Animals↗

PubMed2000

[The attractive effects of nerve regeneration chamber fluid and degenerated nerve segments on the growth and the migration of the cocultured dorsal root ganglion neuron].

OBJECTIVES: We intended in this study to investigate the neurotropic effects of regeneration chamber fluid (RCF) and the degenerated nerve segments from distal of the regeneration chamber on the dorsal root ganglion (DRG). METHODS: The capillary model was first tested for its reliability to form concentration gradient with a dye being contained in the capillaries. The tissue culture in RCF test was divided into two groups each with 8 DRGs implanted in 8 dishes. RCF was contained in capillaries inserted down to the bottom of the dishes with their lower ends at a distance of about 1 mm to the DRGs in the experimental group, and DMEM media was contained in the control group. Segments of degenerated sciatic nerve from distal of the regeneration chamber were implanted with DRGs at a distance of about 0.5 - 1 mm in the coculturing experiment. DRGs were observed for the direction of the growth of the cells and the fibres. RESULTS: While the capillary containing the dye was put down to the bottom of the culture dish coated with a piece of nylon pad, the red color slowly disseminated with heavier staining in the center and lighter staining in the peripheral portion. We believe this pattern of shade could simulate the concentration gradient of tropic factors in this model. There were significantly more nerve fibres growing from the DRGs towards the capillaries in 6 of the 8 dishes in the experimental group after 72 hours of culture. The tissue and nerve fibers grew evenly in the control group. 76.5% of all the nerve fibres were growing in the direction facing the degenerated nerve segments after 12 hours of coculturing, and only 33.3% of the nerve fibres growing in that direction in the control group. Cells from the DRGs migrated towards the degenerated nerve segments, yet they tended to avoid the normal nerve segments. The migration index of the cells was 0.98 in average in the coculturing experiment with the degenerated nerve segments, but only 0.43 in average with the normal nerve coculturing. CONCLUSION: The capillary model was effective in studying the chemotactic growth of nerve tissue. RCF and the degenerated nerve segments had definite neurotropic effects on DRGs tissue.

Animals↗

PubMed2000

[Ultrasonically guided radio-frequency ablation of liver tumors with a clustered electrode: a report of 100 cases].

OBJECTIVE: To evaluate the efficacy of ultrasonically guided radio-frequency (RF) thermal ablation of liver tumors with a clustered electrode. METHODS: Clinical records of 100 consecutive patients who underwent RF tissue ablation 120 times were analysed. Image data, tumor size, clinic manifestation, and AFP value before and after the procedure were compared. RESULTS: A hundred cases at 10 days, thirty at 30 days, ten at 60 days after the procedure were subjected to color ultrasonography and CT scans, respectively. The tumor size decreased by 20% at 10 days in 70% patients, decreased by 30% at 30 days in 80% patients, decreased by 50% at 60 days in 3 patients. AFP value decreased in 50% of patients, no operative death was noted, and the rate of operative complication was 23% after ablation. CONCLUSION: Ultrasound guided RF thermal ablation of hepatic tumors is safe, applicable and effective.

Adolescent↗

PubMed2000

[Vitrectomy for pseudophakic retinal detachment].

OBJECTIVE: To study the method of vitrectomy for treatment of pseudophakic retinal detachment. METHODS: 32 pseudophakic retinal detachment eyes were treated with vitrectomy, primary vitrectomy in 11 eyes (34.4%), vitrectomy after conventional buckling failure in 21 eyes (65.6%), combined with silicone oil 10 eyes (31.3%), removal of intraocular lens 12 eyes (37.5%). All eyes had passed the 6 months to 5 years of follow-up examination. RESULTS: Intra-operative new retinal breaks were identified in 7 eyes (21.9%). The retinal total reattachment was in 25 eyes (78.1%); part reattachment was in 4 eyes (12.5%), and their visual acuity was improved than that before the operation. Due to severe proliferative vitreoretinopathy (PVR), failure occurred in 3 eyes. CONCLUSIONS: The main advantage of vitrectomy is the better intra-operative sight to the peripheral retinal breaks, removal of retinal traction and the low rate of PVR after vitrectomy. Vitrectomy for complicated type of pseudophakic retinal detachment can improve the success rate of the retinal detachment surgery and the visual acuity outcome.

Adult↗

PubMed2000

[Detection of Escherichia coli strains harboring pathogenicity island of Yersinia enterolitica in diarrheal patients and animals in China].

OBJECTIVE: To investigate the prevalence of Escherichia coil strains harboring high pathogenicity island of Yersinia enterocolitica in diarrhea patients, animals, food samples and resulted clinical symptoms. METHODS: Colony hybridization, DNA dot hybridization and polymerase chain reaction (PCR) were used. RESULTS: HPI - harboring E. coli were found in the strains isolated in various provinces of China. The isolation rates were 27.05% (436/1,612) in the strains isolated from diarrhea patients, 10.23% (9/88) in the strains isolated from food samples and 5.71% (16/280) in the strains isolated from feces of cattle and pigs. Typical clinical symptoms of diarrhea caused by HPI - harboring E, coli were inappetency, abdominal pain, shiver and vapidity. Patient's temperature was usually normal or low. Over six episodes of diarrhea was frequently observed, of which most were unformed stools with mucous. CONCLUSION: E. coli strains harboring high - pathogenicity - island of Yersinia species were frequently isolated from diarrhea patients, animals and food samples as well, which might be one of the major causes of diarrhea in China.

Animals↗

PubMed2000

[Infrared study on molecular structure and orientation in Langmuir-Blodgett films of chiral LCs M1].

The LB films of chiral LCs M1 were investigated by FTIR transmission and reflection absorption spectra. CaF2 and vacuum deposition gold plate were used as solid substrate. The LB films can be transferred onto the solid substrate successfully. The orientation of LB films was analysis by comparing the FTIR transmission and reflection absorbance spectroscopy. The aromatic cores part which including the C-O bond was almost perpendicular the substrate surface, the alkyl chain and C=O part has a certain angle titled onto the substrate.

English Abstract↗

PubMed2000

[The dynamics of electric-field-induced molecular reorientation and segmental mobility in the antiferroelectric LCs studied by time-resolved FTIR spectroscopy].

We employed dynamic and polarized infrared spectroscopy to monitor the response of different molecular segments to external electric fields. Measurements of absorbance changes of the representative IR bands as a function of the polarization rotation angle at 109 degrees C under DC electric fields of 0.15 and -15 V determine mutual arrangement of different molecular segments in their equilibrium state in the helicoidal Sm-CA* phase (0 V) and field-induced, unbound Sm-C phase (15 and -15 V). It is clear from the normalized absorbance changes dAn vs wave electric field at 5 KHz repetition rate that the different segments complete the reorientation at different time scales. The core moves faster and takes approximately 33 microseconds to complete the reorientation, while it takes approximately 64 microseconds for the alkyl chains and the C=O group.

English Abstract↗

PubMed2000

[Heat-induced dynamics studies of azobenzene containing long-chain fatty acid by two-dimensional correlational Raman spectroscopy].

Temperature-dependent Fourier transform Raman (FT-Raman) spectra were measured in the temperature range between 30 to 120 degrees C for the azobenzene-containing long chain fatty acid 8A5H in the solid state. Generalized two-dimensional (2D) correlation was applied to calculate temperature-dependent synchronous and asynchronous Raman spectra in order to investigate the sequence of the reorientions arising from the different transient moments associated with molecular vibrations induced by temperature.

Azo Compounds↗

PubMed1999

Transcription of the myogenic regulatory gene Mef2 in cardiac, somatic, and visceral muscle cell lineages is regulated by a Tinman-dependent core enhancer.

The MADS-box transcription factor MEF2 is expressed specifically in developing cardiac, somatic, and visceral muscle cell lineages during Drosophila embryogenesis and is required for myoblast differentiation and muscle morphogenesis. To define the mechanisms that regulate Mef2 transcription, we have analyzed the Mef2 upstream region for sequences sufficient to recapitulate the expression pattern of the gene in Drosophila embryos. Here we describe a complex enhancer located 5.8 kb upstream of the Drosophila Mef2 gene that controls transcription in cardial cells of the dorsal vessel, a subset of somatic muscle founder cells, and the visceral muscle cells. The core of this enhancer contains two evolutionarily conserved binding sites for the homeodomain protein Tinman (Tin), expressed in developing cardiac, somatic, and visceral muscle lineages. Both Tin binding sites are required for enhancer activity in all three muscle cell lineages. Whereas the 285-bp enhancer core alone is sufficient for expression in cardiac cells, expression in somatic founder cells and visceral muscle is dependent on the core enhancer plus unique flanking sequences that include an evolutionarily conserved E box. These results reveal an essential role for Tin in activation of Mef2 transcription in multiple myogenic lineages and demonstrate that transcriptional activity of Tin is dependent on combinatorial interactions with other factors unique to different muscle cell types.

Animals↗

PubMed1999

Oxidized low-density lipoprotein inhibits the binding of monoclonal antibody to platelet glycoprotein IIB-IIIA.

Previous studies have shown that oxidized low-density lipoprotein (LDL) induces platelet activation more effectively than native LDL. To achieve a better understanding of the mechanism underlying the activation of human platelets by oxidized LDL, the present study relates the effect of oxidized LDL to changes of binding characteristics for glycoprotein (GP) IIb-IIIa. Washed human platelets were treated by monoclonal antibody against GP IIb-IIIa, and the ligand-receptor complexes were revealed by immunocytochemical techniques on the ultrastructural level. The localization of the antiglycoprotein IIb-IIIa was time-dependent. After binding to the platelet surface membrane and open canalicular system, the surface-membrane labeling decreased during longer incubation periods. Preincubation with oxidized LDL inhibited the binding of antiglycoprotein IIb-IIIa. Our findings suggest that GP IIb-IIIa acts as a receptor for oxidized LDL. The binding of oxidized LDL to the GP IIb-IIIa might be the first step in platelet activation by plasma lipoproteins.

Antibodies, Monoclonal↗

PubMed1999

A modular, positive selection bacterial artificial chromosome vector with multiple cloning sites.

To construct large-insert libraries for the sequencing, mapping, and functional studies of complex genomes, we have constructed a new modular bacterial artificial chromosome (BAC) vector, pBACe3.6 (GenBank Accession No. U80929). This vector contains multiple cloning sites located within the sacB gene, allowing positive selection for recombinant clones on sucrose-containing medium. A recognition site for the PI-SceI nuclease has also been included, which permits linearization of recombinant DNA irrespective of the characteristics of the insert sequences. An attTn7 sequence present in pBACe3.6 permits retrofitting of BAC clones by Tn7-mediated insertion of desirable sequence elements into the vector portion. The ability to retrofit BAC clones will be useful for functional analysis of genes carried on the cloned inserts. The pBACe3.6 vector has been used for the construction of many genomic libraries currently serving as resources for large-scale mapping and sequencing.

Binding Sites↗