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Biomedical subjects

Jun Wang

Publications and source records attributed to Jun Wang.

At least 289 records · Page 16Linked to original sources
PubMed2005

Histone dynamics on the interleukin-2 gene in response to T-cell activation.

Several models have been proposed for the mechanism of chromatin remodelling across the promoters of inducible genes in mammalian cells. The most commonly held model is one of cooccupation where histone proteins are modified by acetylation or phosphorylation and nucleosomes are remodelled, allowing the assembly of transcription factor complexes. Using chromatin immunoprecipitation, we observed an apparent decrease of histone acetylation and phosphorylation signals at the proximal promoter region of the inducible interleukin-2 and granulocyte-macrophage colony-stimulating factor genes in response to T-cell activation. We showed that this apparent decrease was due to a loss of histone H3 and H4 proteins corresponding to a decrease in nucleosome occupation of the promoter. This histone loss is reversible; it is dependent on the continual presence of appropriate activating signals and transcription factors and is not dependent on the acetylation status of the histone proteins. These data show for the first time that histone proteins are lost from a mammalian promoter upon activation of transcription and support a model of activation-dependent disassembly and reassembly of nucleosomes.

Acetylation↗
PubMed2005

Zinc ribbon domain-containing 1 (ZNRD1) mediates multidrug resistance of leukemia cells through regulation of P-glycoprotein and Bcl-2.

Here, we investigated the role of zinc ribbon domain-containing 1 (ZNRD1) in multidrug resistance (MDR) of leukemia cells and the possible underlying mechanisms. ZNRD1 was found overexpressed in the vincristine-induced MDR leukemia cell HL-60/vincristine moreso than its parental cell HL-60. Up-regulation of ZNRD1 expression could confer resistance of both P-glycoprotein (P-gp)-related and P-gp-nonrelated drugs on HL-60 cells and suppress Adriamycin-induced apoptosis accompanied by decreased accumulation and increased releasing amount of Adriamycin. ZNRD1 could significantly up-regulate the expression of P-gp, Bcl-2, and the transcription of the MDR1 gene but not alter the expression of MDR-associated protein, glutathione S-transferase activity, or intracellular glutathione content in leukemia cells. In addition, inhibition of ZNRD1 expression by RNA interference or P-gp inhibitor could partially reverse ZNRD1-mediated MDR. The further study of the biological functions of ZNRD1 may be helpful for understanding the mechanisms of MDR of leukemia and developing possible strategies to treat leukemia.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2005

Chemokine receptors 6 and 7 identify a metastatic expression pattern in squamous cell carcinoma of the head and neck.

Squamous cell carcinoma of the head and neck (HNSCC) metastasizes predictably to locoregional, cervical lymph nodes. Tumor cells can express various receptors that facilitate metastatic spread to lymph nodes and other nonlymphoid organs. Chemokine receptors (CCRs), normally expressed on lymphocytes, control immune and inflammatory cell migration, providing a link between innate and adaptive immunity. CCR expression was evaluated in HNSCC, and we showed a consistent pattern of CCR6 downregulation and upregulation of CCR7 in metastatic cells and tissues. Functional assays indicate that these surface receptors were functional on metastatic tumor cells. CCR6 downregulation is consistent with its decreased expression in cells emigrating from peripheral mucosal sites, while CCR7, important for homing of immune cells to secondary lymphoid organs, was significantly upregulated. Thus, CCR6, CCR7 and their ligands, normally important in controlling immune cell trafficking in response to inflammatory stimuli, may have an important role in determining the metastasis of HNSCC cells in vivo. Our data indicate that inhibition of CCR signaling may provide a targeted molecular therapy to prevent HNSCC metastasis.

Biomarkers, Tumor↗
PubMed2005

Synthesis of SiO2-coated ZnMnFe2O4 nanospheres with improved magnetic properties.

A core-shell structured composite, SiO2 coated ZnMnFe2O4 spinel ferrite nanoparticles (average diameter of approximately 80 nm), was prepared by hydrolysis of tetraethyl orthosilicate (TEOS) in the presence of ZnMnFe2O4 nanoparticles (average diameter of approximately 10 nm) synthesized by a hydrothermal method. The obtained samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and field emission scanning electron microscopy (FESEM). The magnetic measurements were carried out on a vibrating sample magnetometer (VSM), and the measurement results indicate that the core-shell samples possess better magnetic properties at room temperature, compared with paramagnetic colloids with a magnetic core by a coprecipitation method. These core-shell nanospherical particles with self-assembly under additional magnetic fields could have potential application in biomedical systems.

Coated Materials, Biocompatible↗
PubMed2005

Detecting novel low-abundant transcripts in Drosophila.

Increasing evidence suggests that low-abundant transcripts may play fundamental roles in biological processes. In an attempt to estimate the prevalence of low-abundant transcripts in eukaryotic genomes, we performed a transcriptome analysis in Drosophila using the SAGE technique. We collected 244,313 SAGE tags from transcripts expressed in Drosophila embryonic, larval, pupae, adult, and testicular tissue. From these SAGE tags, we identified 40,823 unique SAGE tags. Our analysis showed that 55% of the 40,823 unique SAGE tags are novel without matches in currently known Drosophila transcripts, and most of the novel SAGE tags have low copy numbers. Further analysis indicated that these novel SAGE tags represent novel low-abundant transcripts expressed from loci outside of currently annotated exons including the intergenic and intronic regions, and antisense of the currently annotated exons in the Drosophila genome. Our study reveals the presence of a significant number of novel low-abundant transcripts in Drosophila, and highlights the need to isolate these novel low-abundant transcripts for further biological studies.

Animals↗
PubMed2005

High-throughput SNP genotyping by single-tube PCR with Tm-shift primers.

Despite many recent advances in high-throughput single nucleotide polymorphism (SNP) genotyping technologies, there is still a great need for inexpensive and flexible methods with a reasonable throughput. Here we report substantial modifications and improvements to an existing homogenous allele-specific PCR-based SNP genotyping method, making it an attractive new option for researchers engaging in candidate gene studies or following up on genome-wide scans. In this advanced version of the melting temperature (Tm)-shift SNP genotyping method, we attach two GC-rich tails of different lengths to allele-specific PCR primers, such that SNP alleles in genomic DNA samples can be discriminated by the Tms of the PCR products. We have validated 306 SNP assays using this method and achieved a success rate in assay development of greater than 83% under uniform PCR conditions. We have developed a standalone software application to automatically assign genotypes directly from melting curve data. To demonstrate the accuracy of this method, we typed 592 individuals for 6 SNPs and showed a high call rate (>98%) and high accuracy (>99.9%). With this method, 6-10,000 samples can be genotyped per day using a single 384-well real-time thermal cycler with 2-4 standard 384-well PCR instruments.

DNA Primers↗
PubMed2005

[Enhanced digitally reconstructed radiographs generated by ray tracing].

Digitally reconstructed radiographs (DRR) which greatly contribute to the quality control of radiotherapy are critical element in the process of virtual simulation in radiotherapy. In this paper, an algorithm based on ray tracing has been used to generate the DRR. By applying an exponential transformation to the electronic density determined by CT value, the generated DRR can be enhanced by adjusting the attenuation and the transformation parameter.

Computer Simulation↗
PubMed2005

[The influence of dissolved oxygen on sonoluminescence].

Abstract Ultrasound at frequency of 1.1 MHz was used to study the sonoluminescence(SL) in air-saturated water at temperature ranging from 283 to 313 K. It was found that the logarithm of the detected SL intensity increases linearly with the dissolved oxygen (DO) concentration. The waters with five kinds of anions in different concentration (mg x L(-1)): Cl(-) (5-25), NO3(-) (0.2-1.8), F- (0.1-2.7), HCO3(-) (8-15), SO4(2-) (0.4-40) were used to simulate natural environmental chemistry background. The experimental results show that the anions in the simulated water have no influence on the SL intensity.

Algorithms↗
PubMed2005

[Physiological responses of Ceratophyllum demersum under different nutritional conditions].

With static experiments, this paper investigated the protein and chlorophyll contents, and the peroxidase (POD) and superoxide dismutase (SOD) activities of Ceratophyllum demersum cultured in meso-, eutro- and hypertrophic and Hoagland's solutions. The results showed that the changes of total N (TN) and total P (TP) concentrations in nutrient solutions had an obvious effect on the biosynthesis of C. demersum. When the concentrations of TN and TP were less than 1 mg x L(-1) and 0.1 mg x L(-1), respectively, the protein and chlorophyll contents of plant declined. The plant from eutrophic solution had higher SOD and POD activities. It was indicated that C. demersum was more preferable to eutropic condition (1 mg TN x L(-1) and 0.1 mg TP x L(-1)), and the raised concentration of nutrients (e. g., hypertrophic and Hoagland's solutions) was a stress to C. demersum and could affect its hardiness physiology.

Ecosystem↗
PubMed2005

[Establishment of cytokine-independent human myelodysplastic cell line and its characteristics].

This study was aimed to establish a cytokine-independent human myelodysplastic cells line from bone marrow of a patient with MDS-CMML. This cell line was incubated in mixed culture of RPMI 1640 and DMEM with 15% bovine serum, but without cytokines; its biological characteristics were identified by morphology, surface marker profiles, cell proliferation, differentiation and apoptosis. The results showed that the established cell line could not depend on cytokines for long-term survival and growth, and could differentiate into colony-forming unit-macrophage, colony-forming unit-megakaryocyte. In conclusion, a cytokine-independent human myelodysplastic syndrome cell line, named MDS-JSN04 (MDS Nanjing Jiansu 04), was established. Its partial biological characteristics were identified and clarified.

Antigens, CD19↗
PubMed2005

[Isolation and degrading characters of pendimethalin degrading bacteria].

Microbial degradation of pendimethalin and the effects of culture conditions in vitro are studied. Twenty-nine strains are isolated by enrichment from soil and sludge. 3 strains can degrade more than 80% of pendimethalin of 100 mg x L(-l) in 3 days in culture fluid. 2 bacteria are considered as efficiently degrading strains identified as Pseudomonas, Mirococcus luteus. The efficiency of degradation is affected by culture conditions such as pH, temperature and the concentration of sucrose and pendimethanlin. The optimal conditions are proposed.

Aniline Compounds↗
PubMed2005

[Dynamics of soil nitrogen, phosphorus and organic matter in alfalfa-crop rotated farmland in semiarid area of Northwest China].

Pasture-crop rotation is regarded as a key planting system in the semiarid area of China's Loess Plateau. This paper studied the dynamics of soil nitrogen, phosphorus and organic matter within the two years of alfalfa-crop rotation. The results showed that in comparing with continuous alfalfa planting, alfalfa-crop rotation induced a decline of soil total nitrogen and organic matter contents by 5.4% and 19.5%, and 46.8% and 28.2%, respectively, in the first and second year, but no significant difference was found in soil total phosphorus. Soil nutrient availability was improved due to the rotation. In the first and second year of rotation, soil nitrate nitrogen and available phosphorus contents increased by 15.5% and 159.1%, and 44.5% and 48.0%, respectively. Planting spring wheat could maintain soil fertility, the second was fallow and planting potato, while planting corn accelerated the depletion of soil total nitrogen, organic matter and available phosphorus. As a result, in the alfalfa-crop rotation, planting spring wheat could be more available to the maintenance of soil fertility.

Biomass↗
PubMed2005

[Effect of human angiopoietin-1 on tumorigenesis and angiogenesis of gastric cancer].

OBJECTIVE: To investigate the role of human angiopoietin-1 (Ang1) in tumorigenesis and angiogenesis of human gastric cancer cell line SGC7901 in nude mice. METHODS: Recombinant human Ang1 sense or antisense eukaryotic expression vectors were constructed, and transfected by lipofectin into human gastric cancer line SGC7901. Stable transfectants were obtained respectively, namely 7Ang1+ for sense, 7Ang1- for antisense, and 7901P for empty vector transfected cells. Semiquantitative PCR and Western blot were employed to testify the transfection efficiency. Cell growth curve and cell cycle were observed by MTT assays or flow cytometry. In in vivo study, growth of SGC7901 xeno-transplant was observed in BALB/c nude mice. Microvessel density (MVD) was analyzed by immunohistochemistry for Factor VIII staining. RESULTS: Stably transfected cell lines were established and decreased expression of Ang1 protein and mRNA in the antisense transfected SGC7901 cells was achieved. Tumorigenesis of 7Ang1- cells on day 30 days was significantly inhibited with decreased MVD as compared to that in 7901P and 7Ang1+ cells (P < 0.01). CONCLUSION: Angiopoietin-1 plays an important role in tumorigenesis and angiogenesis of gastric cancer which can be partially abrogated by antisense technique.

Angiopoietin-1↗
PubMed2005

[Construction of the scaffold model from heterogeneous small blood vessels].

OBJECTIVE: To establish a scaffold model from heterogeneous small blood vessels. METHODS: Caudal arteries from 34 Wistar rats (average length 12.08 +/- 1.69 cm) were made into acellular blood vessel scaffolds. Some scaffolds were observed by electron microscope, and others were transplanted to the cut ends of ear central arteries of male Japanese big ear white rabbits. RESULTS: Average external diameter was 0.74 +/- 0.08 mm in proximal, and 0.55 +/- 0.08 mm in distal end of rat caudal arteries. The small blood vessel scaffolds had shin wall which was white and soft, composed of fibrous tissues without cells. On the intima surface the fibrous tissues were arrayed densely in a grid-like pattern. After transplantation, the blood flow was reserved, and kept flowing freely in 24 hours. The pulsation of the transplanted artery was accessible and no blood leakage was found. CONCLUSION: The natural scaffolds are composed of fibrous tissues, and can sustain the artery pulse pressure for 24 hours. It is better to suture the blood vessels by sleeve anastomosis.

Animals↗
PubMed2005

[Patterns of spasmodic dysphonia and botulinum toxin injections].

OBJECTIVE: To investigate the patterns of spasmodic dysphonia and the outcome treated with botulinum toxin A injections. METHODS: All subjects were studied with acoustic analysis, laryngostroboscopy and laryngeal electromyography (EMG) including motor unit potential measure (MUP), recruitment pattern analysis and evoked electromyography. All the patients with spasmodic dysphonia were received botulinum toxin A (BOTOX) injections in each affected muscles and mostly under electromyographic guidance. RESULTS: Among 22 cases of spasmodic dysphonia, 18 cases of adductor dysphonic patients have strained, strangled voice with intermittent breaks in speech as a consequence of hyperadduction and spasm of the vocal folds during phonation. Two patients had synchronous pharyngeal, lingual and velar tremor. Amplitudes of MUP of thyroarytenoid muscle (TA) were greater in patients group than in normal group (P < 0.01); The recruitment activity was increased and the amplitudes were greater than normal group (700-2500 microV) and the duration of activity of the TA during phonation was also notably greater in patients group than in normal group. Four cases of abductor dysphonic patients have a breathy, effortful hypophonic voice with abrupt termination of voicing. Amplitudes of MUP of posterior cricoarytenoid muscle (PCA) in patients group were increased up to 374 to 538 microV. The recruitment activity was increased and the amplitude was greater than normal(3000-5000 microV). In the adductor dysphonic group, patients who were treated with unilateral toxin injection had good results with 2.5 U or more. The average onset of toxin effect in all adductor dysphonic patients was at 6 hours to 2 days (1.4+/-0. 8) days (x +/- s), with a peak effect at 2 weeks and the follow-up EMG showed fibrillation potentials or electric silence in injected muscle. Duration of benefit was 8 to 24 weeks (15.2 +/- 4.9) weeks. The side-effect of toxin injection were including breathy voice or occasional dysphagia and aspiration. The patients with abductor spasms were less well controlled after PCA injections. CONCLUSIONS: Spasmodic dysphonia was regarded as a neuromuscular diseases, so its diagnosis, classification, treatment and follow-up should depend on not only clinical manifestation but also EMG. Presently, for controlling the dystonic symptoms, the most effective therapy for most of those patients is local BOTOX injections. Repeated injections are required to have a stable results.

Adult↗