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Biomedical subjects

Y Zhang

Publications and source records attributed to Y Zhang.

At least 163 records · Page 9Linked to original sources
PubMed2005

Low-dose methotrexate for the treatment of graft-versus-host disease after allogeneic hematopoietic stem cell transplantation.

Methotrexate (MTX) is commonly used in the prophylaxis of graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT). In order to evaluate the efficacy and safety of low-dose MTX treatment in patients with GVHD after allo-HSCT, 38 patients with acute GVHD (aGVHD), chronic GVHD (cGVHD) or GVHD post-donor lymphocyte infusion (post-DLI GVHD) after allo-HSCT received intravenous MTX at a dose of 5 or 10 mg every 5-- days until a complete or partial response was seen, or there was treatment failure or intolerable side effects. The overall response rate was 94.7% (18/19 patients) in patients with aGVHD, 76.2% (16/21 patients) in patients with cGVHD and 2/2 in patients with post-DLI GVHD. The response rate for GVHD involving various organs was 100% in skin, 75% in gut, 55.6% in liver, 75% in mouth and 100% in the eye, among all enrolled patients. Side effects were minor. Short-term, low-dose MTX is a tolerable and an effective regimen for patients with aGVHD, cGVHD or post-DLI GVHD after allo-HSCT.

Acute Disease↗
PubMed2005

Cellular prion protein inhibits proapoptotic Bax conformational change in human neurons and in breast carcinoma MCF-7 cells.

Prion protein (PrP) prevents Bcl-2-associated protein X (Bax)-mediated cell death, but the step at which PrP inhibits is not known. We first show that PrP is very specific for Bax and cannot prevent Bak (Bcl-2 antagonist killer 1)-, tBid-, staurosporine- or thapsigargin-mediated cell death. As Bax activation involves Bax conformational change, mitochondrial translocation, cytochrome c release and caspase activation, we investigated which of these events was inhibited by PrP. PrP inhibits Bax conformational change, cytochrome c release and cell death in human primary neurons and MCF-7 cells. Serum deprivation-induced Bax conformational change is more rapid in PrP-null cells. PrP does not prevent active caspase-mediated cell death. PrP does not colocalize with Bax in normal or apoptotic primary neurons and cannot prevent Bax-mediated cytochrome c release in a mitochondrial cell-free system. We conclude that PrP protects against Bax-mediated cell death by preventing the Bax proapoptotic conformational change that occurs initially in Bax activation.

Apoptosis↗
PubMed2005

Dendritic cells transduced with an adenovirus vector encoding interleukin-12 are a potent vaccine for invasive pulmonary aspergillosis.

Invasive pulmonary aspergillosis (IPA) is a common and devastating pneumonia. We developed a novel antiinfective vaccine that couples the potent Ag-presenting capacity of dendritic cells (DCs) with paracrine delivery of interleukin-12 (IL-12) to local immune response sites. Our results showed that DCs engulfed Aspergillus conidia through coiling phagocytosis. Transfection of DCs with adenovirus encoding the cDNA of IL-12 did not affect their morphology and capacity to engulf conidia. The transduced DCs secreted IL-12, which was biologically active, to induce the production of gamma interferon (IFN-gamma) from spleen cells. Adoptive transfer of DCs pulsed with heat-inactivated Aspergillus fumigatus (HAF) to naive mice induced the Ag-specific production of IFN-gamma; the transduced HAF-pulsed DCs augmented this immune response further. Animals receiving HAF-pulsed DCs had lower fungal burdens, a more than three-fold higher survival rate at day 3. This protection was associated with a pronounced enhancement in the Aspergillus-specific IFN-gamma response. IL-12-engineered DCs augmented this protection strikingly as judged by a higher survival, and almost no Aspergillus could be detected in the lung of mice that had received IL-12-transduced HAF-pulsed DCs. These results suggest that antigen-pulsed DCs and IL-12 gene therapy could be used as adjunct therapy for aspergillosis.

Adenoviridae↗
PubMed2005

siRNA targeting the leader sequence of SARS-CoV inhibits virus replication.

SARS-CoV (the SARS-Associated Coronavirus) was reported as a novel virus member in the coronavirus family, which was the cause of severe acute respiratory syndrome. Coronavirus replication occurs through a unique mechanism employing Leader sequence in the transcripts when initiating transcription from the genome. Therefore, we cloned the Leader sequence from SARS-CoV(BJ01), which is identical to that identified from SARS-CoV(HKU-39849), and constructed specific siRNA targeting the Leader sequence. Using EGFP and RFP reporter genes fused with the cloned SARS-CoV Leader sequence, we demonstrated that the siRNA targeting the Leader sequence decreased the mRNA abundance and protein expression levels of the reporter genes in 293T cells. By stably expressing the siRNA in Vero E6 cells, we provided data that the siRNA could effectively and specifically decrease the mRNA abundance of SARS-CoV genes as analyzed by RT-PCR and Northern blot. Our data indicated that the siRNA targeting the Leader sequence inhibited the replication of SARS-CoV in Vero E6 cells by silencing gene expression. We further demonstrated, via transient transfection experiments, that the siRNA targeting the Leader sequence had a much stronger inhibitory effect on SARS-CoV replication than the siRNAs targeting the Spike gene or the antisense oligodeoxynucleotides did. This report provides evidence that targeting Leader sequence using siRNA could be a powerful tool in inhibiting SARS-CoV replication.

5' Untranslated Regions↗
PubMed2005

RAS mutation is associated with hyperdiploidy and parental characteristics in pediatric acute lymphoblastic leukemia.

We explored the relationship of RAS gene mutations with epidemiologic and cytogenetic factors in a case series of children with leukemia. Diagnostic bone marrow samples from 191 incident leukemia cases from the Northern California Childhood Leukemia Study were typed for NRAS and KRAS codon 12 and 13 mutations. A total of 38 cases (20%) harbored RAS mutations. Among the 142 B-cell acute lymphoblastic leukemia (ALL) cases, RAS mutations were more common among Hispanic children (P=0.11) or children born to mothers <30 years (P=0.007). Those with hyperdiploidy at diagnosis (>50 chromosomes) had the highest rates of RAS mutation (P=0.02). A multivariable model confirmed the significant associations between RAS mutation and both maternal age and hyperdiploidy. Interestingly, smoking of the father in the 3 months prior to pregnancy was reported less frequently among hyperdiploid leukemia patients than among those without hyperdiploidy (P=0.02). The data suggest that RAS and high hyperdiploidy may be cooperative genetic events to produce the leukemia subtype; and furthermore, that maternal age and paternal preconception smoking or other factors associated with these parameters are critical in the etiology of subtypes of childhood leukemia.

Adolescent↗
PubMed2005

Antitumor effect of antisense ODC adenovirus on human prostate cancer cells.

Ornithine decarboxylase (ODC), the first enzyme of polyamine biosynthesis, was found to increase in cancer cells, especially prostate cancers. Some chemotherapeutic agents aimed to decrease ODC expression showed inhibitory effects on cancer cells. In this study, we examined the effect of adenoviral-transduced antisense ODC on prostate cancer cells. An adenovirus carrying antisense ODC (rAd-ODC/Ex3as) was infected to prostate cancer cells PC-3 and LNCap. Expression of ODC and concentration of polyamines in cells were determined by Western blotting and HPLC. MTT (3-(4,5-methylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide) assay was used to analyze the effect on cell growth. Cell cycle was evaluated by FCM and cellular invasion by Matrigel invasion assay. A nude mouse xenograft model was used to examine tumorigenicity. Expression of ODC in PC-3 and LNCap cells were reduced to 45 and 59%, and three polyamines were also decreased by the rAd-ODC/Ex3as treatment. Consequently, cell growth was substantially inhibited and cell cycle arrested at G1 phase. Matrigel invasion assay showed relatively low invasion. Marked suppression of tumor formation was observed in the xenograft model. This study suggests that rAd-ODC/Ex3as has the antitumor effect on the human prostate cancer cells.

Adenoviridae↗
PubMed2005

Correlating gene expression with chemical scaffolds of cytotoxic agents: ellipticines as substrates and inhibitors of MDR1.

To facilitate a systematic study of chemoresistance across diverse classes of anticancer drug candidates, we performed correlation analyses between cytotoxic drug potency and gene expression in 60 tumor cell lines (NCI-60; NCI-National Cancer Institute). Ellipticine analogs displayed a range of correlation coefficients (r) with MDR1 (ABCB1, encoding multidrug resistance (MDR) protein MDR1 or P-glycoprotein). To determine MDR1 interactions of five ellipticines with diverse MDR1-r values, we employed MDR1-transport and cytotoxicity assays, using MDR1 inhibitors and siRNA-mediated MDR1 downregulation, in MDR1-overexpressing cells. Ellipticines with negative correlations-indicative of MDR1-mediated resistance-were shown to be MDR1 substrates, whereas those with neutral or positive correlations served as MDR1 inhibitors, which escape MDR1-mediated chemoresistance. Correlation with additional genes in the NCI-60 confirmed topoisomerases as ellipticine targets, but suggested distinct mechanisms of action and chemoresistance among them, providing a guide for selecting optimal drug candidates.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2005

Bioremediation of contaminated surface water by immobilized Micrococcus roseus.

The problems caused by contaminated surface water have gradually become more serious in recent years. Although various remediation technologies were investigated, unfortunately, no efficient method was developed. In this paper, a new bioremediation technology was studied using Micrococcus roseus, which was immobilized in porous spherical beads by an improved polyvinyl alcohol (PVA) - sodium alginate (SA) embedding method. The experimental results indicated that COD removal rate could reach 64.7 % within 72 hours when immobilized M. roseus beads were used, which was ten times as high as that of free cells. The optimum inoculation rate of immobilized M. roseus beads was 10 % (mass percent of the beads in water sample, g g(-1)). Suitable aeration was proved necessary to enhance the bioremediation process. The immobilized cells had an excellent tolerance to pH and temperature changes, and were also more resistant to heavy metal stress compared with free cells. The immobilized M. roseus beads had an excellent regeneration capacity and could be reused after 180-day continuous usage. The Scanning Electronic Microscope (SEM) analysis showed that the bead microstructure was suitable for M. roseus growth, however, some defect structures should still be improved.

Alginates↗
PubMed2005

Factors affecting the removal of selected heavy metals using a polymer immobilised Sphagnum moss as a biosorbent.

A hydrophilic polyurethane foam was used to immobilise dried sphagnum moss as a polymer/biomass matrix. This was then tested for its ability to remove Cu(II), Zn(II) and Pb(II) from aqueous solution. Further selected experiments using copper looked at factors which it was thought might affect the performance of the biosorbent. The optimum pH for Cu(II) and Zn(II) sorption was found to be in the range 6 - 7, whilst Pb(II) showed a more uniform sorption profile over the pH range 3 - 8. At pH values above 8 there was significant leaching of organic components from the immobilisation matrix. The immobilised biomass maintained around 90% of its sorption capacity over 10 repetitive cycles of sorption/desorption using HCl as a desorbent with typically > 95% metal ion recovery from each cycle. There were no marked differences in the maximum sorption capacities for Cu(II) using different biomass particle sizes in the immobilisation matrix, but the affinity of the immobilised biomass for Cu(II) decreased with increasing particle size. Alkali and alkaline-earth metal ions did not affect the heavy metal biosorption, but aluminium ion had a significant influence and itself could be adsorbed to a large extent. Acetic acid, urea, and carrageenan did not affect the maximum biosorption capacity of Cu(II), but carrageenan significantly reduced the affinity of biomass to metal ions probably as a result of its own biosorptive properties.

Adsorption↗
PubMed2005

Experimental measurements of particle deposition in three proximal lung bifurcation models with an idealized mouth-throat.

In this paper, particle deposition in three idealized proximal lung bifurcation models with an idealized mouth-throat were investigated experimentally. These bifurcation models included (1) a small symmetric bifurcation, (2) an intermediate asymmetric bifurcation, and (3) a large symmetric bifurcation. An idealized mouth-throat geometry (the "Alberta geometry") was used as the inlet to these bifurcation models. Monodisperse aerosol particles of DEHS (di-2-ethylhexyl-sebecate) oil with mass median diameters in the range of 2.5-7.5 microm were employed at steady flow rates of 30-90 L/min. Particle deposition measurements were conducted by gravimetry. The results show that particle deposition in the mouth-throat and trachea accounts for the major portion of total deposition in the entire models used, and particle deposition fraction in the proximal lung bifurcations is lower compared with that deposited in the regions upstream (the mouth-throat and the trachea). Total particle deposition efficiency increases with increasing either inertial parameter or Stokes number. Total particle deposition varies appreciably from model to model. The laryngeal jet is the key factor dominating particle deposition within the trachea. An effect of Reynolds number on particle deposition efficiency in the trachea is observed. In addition, particle deposition in the bifurcation region is influenced little by the upstream flow condition, and therefore the effect of the laryngeal jet on deposition seemingly does not propagate to the bifurcations downstream.

Administration, Inhalation↗
PubMed2005

Analysis of a bovine herpesvirus 1 recombinant virus that does not express the bICP0 protein.

Bovine herpesvirus 1 (BHV-1) infected-cell protein 0 (bICP0) stimulates productive infection by activating viral gene expression. In this study, an attempt was made to construct a recombinant virus with point mutations in the C(3)HC(4) zinc RING finger of bICP0, as this domain is necessary for activating viral transcription and productive infection. A virus was identified in bovine cells that induced small clusters of infected cells resembling a small plaque. Instead of the expected mutations within the zinc RING finger, this virus contained a point mutation within the initiating ATG of bICP0, a point mutation two bases downstream from the ATG mutation and deletion of flanking plasmid sequences used for homologous recombination. The bICP0 mutant was rescued with wild-type (wt) bICP0 sequences and the bICP0-rescued virus produced wt plaques. The bICP0-rescued virus and wt BHV-1, but not the mutant, expressed the bICP0 protein during productive infection of bovine cells, suggesting that the mutant virus was a null mutant. Consequently, the mutant was designated the bICP0 null mutant. Infection of bovine cells with the bICP0 null mutant resulted in at least 100-fold lower virus titres, indicating that bICP0 protein expression is important, but not required, for virus production. When bovine cells infected with the bICP0 null mutant virus were subcultured, the cells continued to divide, but viral DNA could be detected after more than 35 passages, suggesting that the bICP0 null mutant induced a persistent-like infection in bovine cells and that it may be useful for generating additional bICP0 mutants.

Animals↗
PubMed2005

Common and contrasting genomic profiles among the major human lung cancer subtypes.

Lung cancer is the leading cause of cancer mortality worldwide. With the recent success of molecularly targeted therapies in this disease, a detailed knowledge of the spectrum of genetic lesions in lung cancer represents a critical step in the development of additional effective agents. An integrated high-resolution survey of regional amplifications and deletions and gene expression profiling of non-small-cell lung cancers (NSCLC) identified 93 focal high-confidence copy number alterations (CNAs), with 21 spanning less than 0.5 Mb with a median of five genes. Most CNAs were novel and included high-amplitude amplification and homozygous deletion events. Pathogenic relevance of these genomic alterations was further reinforced by their recurrence and overlap with focal alterations of other tumor types. Additionally, the comparison of the genomic profiles of the two major subtypes of NSCLC, adenocarcinoma (AC) and squamous cell carcinoma (SCC), showed an almost complete overlap with the exception of one amplified region on chromosome 3, specific for SCC. Among the few genes overexpressed within this amplicon was p63, a known regulator of squamous cell differentiation. These findings suggest that the AC and SCC subtypes may arise from a common cell of origin and they are driven to their distinct phenotypic end points by altered expression of a limited number of key genes such as p63.

Adenocarcinoma↗
PubMed2005

Differential gene expression in liver of inbred chickens and their hybrid offspring.

Differential display of mRNA was used to analyse the differences of gene expression in liver between chicken hybrids and their parents in a 4 x 4 diallel crosses in order to study the molecular basis of heterosis in chickens. The results indicated that patterns of gene expression in hybrids differ significantly from their parents. Four patterns of differential gene expression were revealed, which included: (i) bands only detected in the hybrid F1s (UNF1); (ii) bands only absent in the hybrid F1s (ABF1); (iii) bands only detected in the parental P1 or P2 lines (UNP1 and UNP2) and (iv) bands absent in the parental P1 or P2 lines (ABP1 and ABP2). In addition, correlations between patterns of gene expression and heterosis percentages of nine carcass traits of 8-week-old chickens were evaluated. Statistical results showed that negative correlations between heterosis percentages and the percentage of F1-specific bands (UNF1) were significant at P < 0.01 for breast muscle yield, leg muscle yield, wing weight, eviscerated weight and eviscerated weight with giblet of 8-week-old chickens, and at P < 0.05 for intermuscular fat width. Heterosis percentage was negatively correlated with ABP (bands present in the hybrid F1s and one parental line but absent in the other parental line, ABP1 and ABP2) for breast muscle yield, leg muscle yield, wing weight, eviscerated weight and eviscerated weight with giblet of 8-week-old chickens (P < 0.01). Bands detected only in the hybrid F1s but not in either of the parental lines (UNF1) and bands absent in parental P1 or P2 lines (which includes ABP1 and ABP2) may play important roles in chicken heterosis.

Animals↗
PubMed2005

Glucocorticoids suppress transcriptional up-regulation of bradykinin receptors in a murine in vitro model of chronic airway inflammation.

BACKGROUND: Glucocorticoids are effective drugs for controlling symptoms and airway inflammation in respiratory diseases such as asthma and chronic obstructive pulmonary disease. However, the mechanisms behind their effects are not fully understood. We have recently demonstrated that prolonged exposure to the pro-inflammatory mediator tumour necrosis factor-alpha (TNF-alpha) markedly enhanced contractile responses to des-Arg9-bradykinin (selective bradykinin B1 receptor agonist) and bradykinin (selective bradykinin B2 receptor agonist) in murine airways. This increase was paralleled with elevated mRNA levels for bradykinin B1 and B2 receptors, a process involving intracellular mitogen-activated protein kinase pathways. OBJECTIVE: To investigate the effects of glucocorticoids on the TNF-alpha up-regulated bradykinin B1 and B2 receptor response. METHODS: Tracheal segments from BALB/c J mice were cultured with and without TNF-alpha, in the absence and presence of the transcriptional inhibitor actinomycin D or the glucocorticoid, dexamethasone. The contractile response induced by des-Arg9-bradykinin and bradykinin was subsequently assessed in a myograph system and mRNA for bradykinin B1 and B2 receptors was quantified using real-time polymerase chain reaction. RESULTS: Actinomycin D abolished and dexamethasone concentration-dependently suppressed the TNF-alpha-induced enhancement of the des-Arg9-bradykinin and bradykinin responses. This was paralleled by a reduction of the mRNA expression for the bradykinin B1 and B2 receptors. CONCLUSION: The presented data suggests the involvement of transcriptional mechanisms in the up-regulation of bradykinin B1 and B2 receptors during asthmatic airway inflammation, as well as in their down-regulation following glucocorticoid treatment.

Animals↗
PubMed2005

Direct characterization of human T cells in pemphigus vulgaris reveals elevated autoantigen-specific Th2 activity in association with active disease.

Pemphigus vulgaris (PV) is a blistering skin disorder mediated by autoantibodies targeting the epidermal adhesion molecule desmoglein 3 (Dsg3). As Th2-associated cytokines are necessary for directing antibody production, it is hypothesized that Dsg3-specific Th2 activity is associated with active disease. We used cell-surface-matrix technology in combination with flow cytometry to characterize the Dsg3-reactive T-cell population using peripheral blood mononucleocytes sampled from PV patients stratified by active (n = 9) or remittent disease (n = 6), and healthy human leucocyte antigen-matched controls (n = 5). We evaluated interferon-gamma-producing CD4+ cells (Th1) and interleukin (IL)-10- or IL-4-producing CD4+ cells (Th2). The mean frequency of Th2 CD4+ T cells was significantly elevated for five of nine PV patients with active disease. No significant Th2 responses were detected for patients with remittent disease or controls. There was a significant association of Th2 activity with active disease compared with remittent and control groups (P = 0.026 and P =0.012, respectively), and Th2 activity was significantly correlated with anti-Dsg3 IgG titre (P = 0.044). One patient with remittent disease converted from a Th2-negative to a Th2-positive response with the initiation of disease activity. An antigen-specific CD4- lymphocyte response was detected in five PV patients (36%), and was shown to correlate closely with the CD8+ population. These results are consistent with the hypothesis that Th2 response directs autoantibody production and is therefore associated with disease activity in PV.

Autoantibodies↗
PubMed2005

Anti-endothelial cell antibodies (AECA) in patients with propylthiouracil (PTU)-induced ANCA positive vasculitis are associated with disease activity.

Increasing evidence has demonstrated that propylthiouracil (PTU) could induce ANCA positive vasculitis. However, our previous work has suggested that only one-fifth of the PTU-induced ANCA positive patients had clinical vasculitis and so the mechanism is not clear. Anti-endothelial cell antibodies (AECA) have been implicated in the pathogenesis of various vasculitides, including primary ANCA positive systemic vasculitis. The purpose of this study is to investigate the prevalence of AECA and their possible role in the pathogenesis of patients with PTU-induced ANCA positive vasculitis. Sera from 11 patients with PTU-induced ANCA positive vasculitis at both active and quiescent phases, and sera from 10 patients with PTU-induced ANCA but without clinical vasculitis, were studied. Sera from 30 healthy blood donors were collected as normal controls. Soluble proteins from 1% Triton-100 extracted in vitro cultured human umbilical vein endothelial cells were used as antigens and an immunoblotting technique was performed to determine the presence of AECA, and their specific target antigens were identified. In patients with PTU-induced ANCA positive vasculitis, 10 of the 11 patients in an active phase of disease were serum IgG-AECA positive and six protein bands of endothelial antigens could be blotted (61 kD, 69 kD, 77 kD, 85 kD, 91 kD and 97 kD). However, in the quiescent phase, seven of the 10 positive sera turned negative. None of the ANCA positive but vasculitis negative patients or normal controls were AECA positive. In conclusion, AECA could be found in sera from patients with PTU-induced ANCA positive vasculitis and were associated more closely with vasculitic disease activity.

Adolescent↗