Biomedical subjects

Ying Zheng

Publications and source records attributed to Ying Zheng.

At least 37 records · Page 2Linked to original sources

PubMed2005

Attenuated alloreactivity of dendritic cells engineered with surface-modified microspheres carrying a plasmid encoding interleukin-10.

In the present study, we investigated MS(O10H6) as a carrier system to introduce a plasmid encoding murine interleukin-10 (pIL-10) to modulate alloreactivity of dendritic cells (DC). Results indicate that MS(O10H6) formed stable and protective nano-sized particles with pIL-10. Gene-modified DC elicited weak proliferation of allogeneic CD4 and CD8 T cells in vitro. Using cell-embedded Matrigel as a surrogate graft, we also showed that DC transfected with MS(O10H6) complexed with pIL-10 suppressed host cell infiltration in vivo. These data demonstrate that the self-assembled system of MS(O10H6) is an effectual delivery vehicle for plasmid-based modulation of DC-dependent allogeneic T cell responses.

Animals↗

PubMed2005

Detecting correlation between sequence and expression divergences in a comparative analysis of human serpin genes.

Physiological functions and characteristic structures of the serpin gene superfamily have been studied extensively, yet the evolution of the serpin genes remains unclear. Gene duplication in this superfamily may shed light on this issue. Two models are used to predict the preservation of duplicated genes: the classical model and the duplication-degeneration-complementation (DDC) model. In this study, we analyzed the phylogenetic relationships of 33 human serpin genes and the expression data of some members of the serpin superfamily from a DNA microarray of human leukemia U937 cells with stably inducible expression of the leukemia-related AML1-ETO gene. We then determined the utility of the DDC model by mapping serpin superfamily expression data to the phylogenetic tree. The correlation between sequence and expression divergences as measured by the Pearson correlation coefficient indicated that human serpin genes evolved under the DDC model. Our study provides a new strategy for comparative analysis of gene sequences and microarray data.

Cell Line, Tumor↗

PubMed2005

A three-compartment model of the hemodynamic response and oxygen delivery to brain.

We describe a mathematical model linking changes in cerebral blood flow, blood volume and the blood oxygenation state in response to stimulation. The model has three compartments to take into account the fact that the cerebral blood flow and volume as measured concurrently using laser Doppler flowmetry and optical imaging spectroscopy have contributions from the arterial, capillary as well as the venous compartments of the vasculature. It is an extension to previous one-compartment hemodynamic models which assume that the measured blood volume changes are from the venous compartment only. An important assumption of the model is that the tissue oxygen concentration is a time varying state variable of the system and is driven by the changes in metabolic demand resulting from changes in neural activity. The model takes into account the pre-capillary oxygen diffusion by flexibly allowing the saturation of the arterial compartment to be less than unity. Simulations are used to explore the sensitivity of the model and to optimise the parameters for experimental data. We conclude that the three-compartment model was better than the one-compartment model at capturing the hemodynamics of the response to changes in neural activation following stimulation.

Animals↗

PubMed2005

The protein X4 of severe acute respiratory syndrome-associated coronavirus is expressed on both virus-infected cells and lung tissue of severe acute respiratory syndrome patients and inhibits growth of Balb/c 3T3 cell line.

BACKGROUND: The genome of the severe acute respiratory syndrome-associated coronavirus (SARS-CoV) includes sequences encoding the putative protein X4 (ORF8, ORF7a), consisting of 122 amino acids. The deduced sequence contains a probable cleaved signal peptide sequence and a C-terminal transmembrane helix, indicating that protein X4 is likely to be a type I membrane protein. This study was conducted to demonstrate whether the protein X4 was expressed and its essential function in the process of SARS-CoV infection. METHODS: The prokaryotic and eukaryotic protein X4-expressing plasmids were constructed. Recombinant soluble protein X4 was purified from E. coli using ion exchange chromatography, and the preparation was injected into chicken for rising specific polyclonal antibodies. The expression of protein X4 in SARS-CoV-infected Vero E6 cells and lung tissues from patients with SARS was performed using immunofluorescence assay and immunohistochemistry technique. The preliminary function of protein X4 was evaluated by treatment with and over-expression of protein X4 in cell lines. Western blot was employed to evaluate the expression of protein X4 in SARS-CoV particles. RESULTS: We expressed and purified soluble recombinant protein X4 from E.coli, and generated specific antibodies against protein X4. Western blot proved that the protein X4 was not assembled in the SARS-CoV particles. Indirect immunofluorescence assays revealed that the expression of protein X4 was detected at 8 hours after infection in SARS-CoV-infected Vero E6 cells. It was also detected in the lung tissues from patients with SARS. Treatment with and overexpression of protein X4 inhibited the growth of Balb/c 3T3 cells as determined by cell counting and MTT assays. CONCLUSION: The results provide the evidence of protein X4 expression following SARS-CoV infection, and may facilitate further investigation of the immunopathological mechanism of SARS.

Amino Acid Sequence↗

PubMed2005

Differential profiles of copper-induced ROS generation in human neuroblastoma and astrocytoma cells.

To determine neuronal and glial responses to copper (Cu) elevation in the CNS, human neuroblastoma and astrocytoma cells were used to compare their responses to Cu in terms of reactive oxygen species (ROS) generation and expression of enzymes responsible for anti-oxidation. Astrocytoma cells, not neuroblastoma cells, were responsive to Cu and Cu elevation was associated with ROS generation. Intracellular Cu levels as determined by inductively coupled plasma-mass spectrometry (ICP-MS), and expression levels of copper-transporting ATPase (ATP7A) and human copper transporter 1 (hCtr1) as detected by quantitative reverse transcription-polymerase chain reaction (RT-PCR), were comparable in both cell lines. Differences in Cu-induced ROS between two cell lines paralleled superoxide dismutase (SOD)-catalase expression as detected by Western blot analysis. Copper,zinc-SOD (Cu,Zn-SOD) and catalase protein levels were upregulated by Cu in neuroblastoma cells while Cu,Zn-SOD was down-regulated by Cu and catalase level was not changed in astrocytoma cells. Manganese-SOD (Mn-SOD) was not responsive to Cu in either cell line. Furthermore, 78-kDa glucose-regulated protein aggregation and upregulation were observed in Cu-treated astrocytoma cells, but not neuroblastoma cells. These data suggest that neurons use the SOD-catalase system to scavenge Cu-induced ROS while glia rely on the endoplasmic reticulum stress response to compensate for the reduction of ROS scavenging capacity.

Adenosine Triphosphatases↗

PubMed2005

Physicochemical and structural characterization of quercetin-beta-cyclodextrin complexes.

Quercetin is a bioactive flavonoid widely used as a health supplement. Being sparingly soluble and chemically unstable in aqueous intestinal fluids, quercetin is poorly absorbed orally. This study aimed to investigate the effects of three beta-cyclodextrins, namely, unsubstituted beta-cyclodextrin (beta-CD), hydroxypropyl-beta-cyclodextrin (HP-beta-CD), and sulfobutyl ether beta-cyclodextrin (SBE-beta-CD) on the chemical stability and water solubility of quercetin, and to elucidate the complexation mechanisms of these beta-CDs with quercetin. Quercetin-beta-CD complexes in solution were characterized by stability assessment, phase solubility measurements, and 1H-nuclear magnetic resonance (NMR) spectroscopy. Molecular modeling was used to help establish the mode of interaction of the beta-CDs with quercetin. Solubility enhancements of quercetin obtained with the three beta-CDs followed the rank order: SBE-beta-CD > HP-beta-CD > beta-CD. The stability of quercetin at alkaline pHs also showed substantial improvement. NMR spectroscopic analysis suggested that the B-ring, C-ring, and part of the A-ring of quercetin display favorable interaction with the hydrophobic cavity of the beta-CDs, which was confirmed by molecular dynamics (MD) simulations using a solvated model of the quercetin-beta-CD complex. An inclusion complex model has been established for explaining the observed augmentation of solubility and stability of quercetin in water by beta-CDs.

Chemical Phenomena↗

PubMed2005

The involvement of copper transporter in lead-induced oxidative stress in astroglia.

Lead (Pb), depositing primarily in astroglia in the brain, is a well-known neurotoxicant and a risk factor for neurologic disorders. Pb has been reported to induce oxidative stress by probably the disturbance of copper (Cu) homeostasis in astroglia. Thus, we hypothesized that Pb-induced oxidative stress is initiated by interfering with Cu transporter in astroglia. In this study, we observed Pb-induced oxidative stress as indicated by reactive oxygen species (ROS) augmentation and GRP78 and GRP94 protein induction, and it was parallel to Cu accumulation intracellularly by Pb. To further address Cu transporter as a potential Pb target, a heavy metal-binding (HMB) domain of Cu-transporting ATPase (Atp7a) was overexpressed and purified. Evidence showed that one molecule of HMB chelated 11 Pb ions or seven Cu ions and that Pb competed with Cu for binding to HMB. These findings suggest that Pb-induced oxidative stress results from the impairment of Cu metabolism by Pb targeting of Atp7a.

Adenosine Triphosphatases↗

PubMed2005

Polymeric microspheres as stabilizing anchors for oligonucleotide delivery to dendritic cells.

The aim of this study is to evaluate a novel microspheric vector for delivery of oligonucleotides (ODN) into dendritic cells (DC). A requirement of decoy-based modulation of transcriptional activities in DC is that the ODN would have to accumulate inside the cell. Using an ex vivo DC culture model, we demonstrate that anionic microspheres (MS) coated with an ornithine/histadine-based cationic peptide (O10H6) is an effective carrier of short ODN. This method does not disrupt the colloidal nature of the microspheric particles. The MS provide stabilizing effect on DNA and O10H6 complexation. Accumulation of ODN in DC is greatly enhanced with the surface modified MS. Taken together, these data demonstrate that the self assembly system of MS(O10H6) is an effective delivery vehicle for DNA-based modulation of DC functions.

Animals↗

PubMed2005

GRP78 compartmentalized redistribution in Pb-treated glia: role of GRP78 in lead-induced oxidative stress.

Glucose-regulated protein of 78 kDa (GRP78) is an endoplasmic reticulum (ER) molecular chaperone functioning in protein folding, assembly and trafficking. GRP78 also plays a role in protection against cytotoxicity and apoptosis induced by environmental insults. Our previous study showed that lead (Pb) directly targets GRP78 by binding to the protein and increasing GRP78 levels. In this study, the effect of Pb on compartmentalized distribution of GRP78 in living cells was examined. A rat GRP78-EGFP fusion protein and EGFP were transiently expressed in astrocytoma cells exposed to 5 microM Pb acetate or 50 microM CuSO4 and fluorescence signals were captured. Control cells expressing EGFP showed a homogeneous distribution of EGFP that was not changed by Pb or Cu treatment. Cells expressing GRP78-EGFP showed a compartmentalized, non-homogeneous distribution of GRP78-EGFP in the cytosol. The redistribution of GRP78-EGFP fluorescent bodies was observed in cells exposed to Pb for 10 h, but not 5 h. Redistribution was also observed in cells exposed to 50 microM Cu for 5 or 10 h. To assess GRP78 function, GRP78 was depleted with dsRNAi oligos in rat C6 glioma cells. GRP78 depletion significantly increased the sensitivity of cells to Pb exposure as indicated by the generation of reactive oxygen species (ROS). These data suggest that Pb directly targets GRP78 and induces its compartmentalized redistribution in living cells and that GRP78 plays a protective role in Pb neurotoxicity.

Animals↗

PubMed2005

Long duration stimuli and nonlinearities in the neural-haemodynamic coupling.

Recent studies have shown that the haemodynamic responses to brief (<2 secs) stimuli can be well characterised as a linear convolution of neural activity with a suitable haemodynamic impulse response. In this paper, we show that the linear convolution model cannot predict measurements of blood flow responses to stimuli of longer duration (>2 secs), regardless of the impulse response function chosen. Modifying the linear convolution scheme to a nonlinear convolution scheme was found to provide a good prediction of the observed data. Whereas several studies have found a nonlinear coupling between stimulus input and blood flow responses, the current modelling scheme uses neural activity as an input, and thus implies nonlinearity in the coupling between neural activity and blood flow responses. Neural activity was assessed by current source density analysis of depth-resolved evoked field potentials, while blood flow responses were measured using laser Doppler flowmetry. All measurements were made in rat whisker barrel cortex after electrical stimulation of the whisker pad for 1 to 16 secs at 5 Hz and 1.2 mA (individual pulse width 0.3 ms).

Algorithms↗

PubMed2005

Sabian, a novel flavonoid from Sabiayunnanensis.

A novel flavonoid, [2-(3,4-dihydroxy-phenyl)-3,5,7-trihydroxy-4-oxo-4H-chromen-8-yl]-[8-hydroxy-7-(E-4-hydroxy-3-methyl-but-2-enyl)-2,2-dimethyl-chroman-5-yl]-acetic acid methyl ester (10), trivially named sabian, along with 11 known compounds, have been isolated from the stems and leaves of Sabiayunnanensis. Their structures were established on the basis of spectral analysis.

Flavonoids↗

PubMed2005

Organogenesis from dissociated cells: generation of mature cycling hair follicles from skin-derived cells.

Hair follicle formation and cycling involve extensive and continuous interactions between epithelial and mesenchymal components. A system for rapidly and reproducibly generating hair follicles from dissociated epithelial and mesenchymal cells is described here. The system serves both as a tool for measuring the trichogenic property of cells and as a tool for studying the mechanisms that dissociated cells use to assemble an organ. In this system, hair follicles develop when dissociated cells, isolated from newborn mouse skin, are injected into adult mouse truncal skin. This morphogenetic process involves the aggregation of epithelial cells to form clusters that are sculpted by apoptosis to generate "infundibular cysts". From the "infundibular cysts", hair germs form centrifugally followed by follicular buds and then pegs that grow asymmetrically to differentiate into cycling mature pilosebaceous structures. Marker studies correlate the molecular differentiation of these follicles with in situ systems. This study suggests that the earliest phase of a developing epithelial-mesenchymal system--even from dissociated cell preparations--requires an epithelial platform.

Animals↗

PubMed2005

Identification and characterization of the BGR-like gene with a potential role in human testicular development/spermatogenesis.

AIM: To investigate the roles of the BGR-like gene in testicular development/spermatogenesis. METHODS: A human testis cDNA microarray was hybridized with probes from human adult testes and embryo testes. The differentially expressed clones were sequenced and analyzed. Expression of the BGR-like gene was analyzed by reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: A new gene exhibiting 50-fold difference in expression level between adult and fetal human testes was cloned and named the BGR-like gene. The cDNA consisted of 2500 nucleotides and had an open reading frame of 1437 nucleotides encoding a putative protein of 497 amino acid residues. Homologous comparison showed that the BGR-like gene was a new alternative splicing variant of the BGR gene and had sequence homology with the bubblegum gene of human, mouse, rat and Drosophila. Protein motif analysis of the BGR-like gene revealed that it contained a conserved adenosine monophosphate (AMP)-binding domain and a fatty acyl-CoA synthetase signature motif which existed in all acyl-CoA synthetases. The BGR-like gene transcript was imperceptibly expressed in human fetal testes, highly in human adult testes and moderately in elderly testes and human Leydig cells. RT-PCR-based tissue distribution experiments showed that the BGR-like gene was exclusively expressed in testes and was a testes-specific isoform of the BGR gene. A BGR-like gene transcript was not detected in some azoospermic testes. CONCLUSION: The BGR-like gene may play an important role in spermatogenesis/testicular development and may be correlated with male infertility.

Adult↗

PubMed2005

Expression of a novel beta adaptin subunit mRNA splice variant in human testes.

AIM: To identify a novel isoform of adaptin 2 beta subunit (named Ap2beta-NY) and to investigate its relationship with testicular development and spermatogenesis. METHODS: Using a human testis cDNA microarray, a clone (Ap2beta-NY), which was strongly expressed in adult testes but weakly expressed in embryo testes, was sequenced and analyzed. Using polymerase chain reaction (PCR), the tissue distribution and expression time pattern of Ap2beta-NY were determined. RESULTS: Ap2beta-NY was identified and has been deposited in the GenBank (AY341427). The expression level of Ap2beta-NY in the adult testis was about 3-fold higher than that in the embryo testis. PCR analysis using multi-tissue cDNA indicated that Ap2beta-NY was highly expressed in the testis, spleen, thymus, prostate, ovary, blood leukocyte and brain, but not in the heart, placenta, lung, liver, skeletal muscle, kidney and pancreas. In addition, Ap2beta-NY was variably expressed in the testes of patients with spermatogenesis-disturbance and spermatogenesis-arrest but not expressed in those of Sertoli-cell-only syndrome, which implied that, in the testis, Ap2beta-NY was restrictively expressed in germ cells. CONCLUSION: Ap2beta-NY is an isoform of Ap2beta and may be involved in regulating the process of spermatogenesis and testis development.

Adaptor Protein Complex beta Subunits↗

PubMed2005

Expression of a novel alternative transcript of the novel retinal pigment epithelial cell gene NORPEG in human testes.

AIM: To identify a novel alternative transcript of the novel retinal pigment epithelial cell gene (NORPEG) expressed in the human testis. METHODS: A human testis cDNA microarray was established and hybridized with cDNA probes from human fetal testes, adult testes and human spermatozoa. Differentially expressed clones were sequenced and analyzed. One of these clones was a short transcript of NORPEG which we proceeded to analyze by RT-PCR. RESULTS: The novel short alternative transcript of NORPEG was isolated and named sNORPEG. It was 3486 bp in length and contained a 2952-bp open reading frame, encoding a 110.4-kDa protein of 983 amino acids. Amino acid sequence analysis showed that the sNORPEG protein contains six ankyrin repeats and two coiled-coil domains. It shares a high homology with the NORPEG and ankycorbin proteins in both its sequence and motifs. Blasting the human genome database localized sNORPEG to human chromosome 5p13.2-13.3. Expression profiles showed that sNORPEG was expressed in human fetal testes, adult testes and spermatozoa. Moreover, sNORPEG was found to be ubiquitously expressed in human tissues. CONCLUSION: sNORPEG is expressed in different developmental stages of the testis and encodes a protein that may have roles in human testis development and spermatogenesis.

Alternative Splicing↗

PubMed2005

Molecular cloning and expression of a novel alternative splice variant of BRDT gene.

In this study, a human adult testis cDNA microarray was constructed and hybridized with (33)P-labeled human adult testis, embryo testis and sperm cDNA probes, respectively. A novel alternative splice variant of BRDT gene, named BRDT-NY, presumably involved in testicular function was cloned. It was expressed 3.96-fold more in human adult than embryo testis and also expressed in human spermatozoa. Similarly, RT-PCR revealed a differential expression pattern of this gene in human adult testes and fetal testes. The full length of BRDT-NY was 3438 bp and contained a 2883 bp open reading frame, encoding a 960-amino-acid protein. Sequence analysis showed that it has two bromodomains in N-terminal of the protein. Multiple tissue RT-PCR results showed that BRDT-NY was exclusively expressed in testis. mRNA expression of BRDT-NY gene was deleted in some azoospermic patients' testes. These experiments suggested that BRDT-NY gene may have an important role in the process of spermatogenesis and may be correlated with male infertility.

Alternative Splicing↗

PubMed2005

[Development of a fusion toxin IL15M-PEdelta293 based on a receptor-specific IL-15 antagonist].

IL-15 and IL-15 receptors (IL-15R) play a crucial role in the pathogenesis of adult T-cell leukemia (ATL), multiple myeloma and inflammatory autoimmune diseases. To develop a novel therapeutic agent capable of eliminating IL-15R-over-expressing abnormal cells, the gene coding for human IL-15 antagonist (IL-15M) was fused with a DNA fragment coding for the mutated form of Pseudomonas exotoxin, PEdelta293. The resulting gene fusion was cloned into pET16b under the control of T7 promoter, giving rise to the expression plasmid pET-IL15M-PEdelta293. Using Ni2+ -NTA affinity chromatography, IL15M-PEdelta293 was purified from E. coli BL21 (DE3) pLysS transformed with pET-IL15M-PEdelta293. The fusion toxin showed cytotoxicity to IL-15R-bearing myelogenous leukemia cell line K562 and K562-derived multidrug resistant cell line K562/AO2. However, IL-15R negative cell line Jurkat was insensitive to IL15M-PEdelta293. In addition, the toxic effect of IL15M-PEdelta293 on K562 was completely blocked by excessive amount of recombinant human IL-15. These results demonstrated that the selective cytotoxicity of IL15M-PEdelta293 correlated with the appropriate IL-15R expression on target cells. The present data suggest that the chimeric toxin constructed in this report may have therapeutic potential in the treatment of diseases associated with abnormal expression of IL-15/IL-15R, even in the treatment of chemotherapy refractory tumors.

Escherichia coli↗

PubMed2005

Synthetic peptides outside the spike protein heptad repeat regions as potent inhibitors of SARS-associated coronavirus.

A novel severe acute respiratory syndrome (SARS)-associated coronavirus (SARS-CoV) has been identified as the aetiological agent of SARS. We previously isolated and characterized SARS-CoV and SARS-CoV-like viruses from human and animals, respectively, suggesting that SARS could be transmitted from wild/farmed animals to humans. Comparison of the viral genomes indicated that sequence variation between animal and human isolates existed mainly in the spike (S) gene. We hypothesized that these variations may underlie a change of binding specificity of the S protein to the host cells, permitting viral transmission from animals to humans. Here we report that four 20-mer synthetic peptides (S protein fragments), designed to span these sequence variation hotspots, exhibited significant antiviral activities in a cell line. SARS-CoV infectivity was reduced over 10 000-fold through pre-incubation with two of these peptides, while it was completely inhibited in the presence of three peptides. Molecular modelling of the SARS-CoV peplomer suggests that three of these antiviral peptides map to the interfaces between the three monomers of the trimeric peplomer rather than the heptad repeat region from which short peptides are known to inhibit viral entry. Our results revealed novel regions in the spike protein that can be targeted to inhibit viral infection. The peptides identified in this study could be further developed into antiviral drugs.

Amino Acid Sequence↗