Biomedical subjects

Ya-Dong Wang

Publications and source records attributed to Ya-Dong Wang.

8 recordsLinked to original sources

PubMed2006

Human Flt3 ligand from Pichia pastoris inhibits growth of lymphoma and colon adenocarcinoma in mice.

UNLABELLED: Potent effects of Flt3 ligand (FL) on the development of the immune system have generated much interest in application of FL in cancer immunotherapy. OBJECTIVE: To evaluate the effects of Pichia pastoris secreted rhFL on the growth of mouse EL-4 lymphoma and C26 colon adenocarcinoma injected in syngeneic mice for the first time. METHODS: Mice were placed into one of two treatment groups. 2 x 10(5) EL-4 or C26 cells were injected subcutaneously (SC.) into mice on day 0. Group 1 received subcutaneous PBS injections from Day -7 to Day 14 and group 2 received subcutaneous rhFL injections at 30 microg/day from Day -7 to Day 14. Serial tumor areas were measured. On Day 22, mice from each group were sacrificed, and weight of tumors and spleens were evaluated. Data analysis used Student t tests. RESULTS: Pichia pastoris secreted rhFL resulted in tumor growth delay for both EL-4 lymphoma and C26 colon adenocarcinoma compared with control (P < 0.01). Tumors from rhFL-treated mice were smaller (P < 0.01) than controls while spleens larger (P < 0.01) than controls. Histological examination of tumor sections revealed an obvious increase in regions composed largely of infiltrating cells in the rhFL-treated tumors. Infiltrating cells could be detected in clusters among tumors from mice treated with rhFL whereas these cells were only occasionally detected in sections of control tumors. CONCLUSION: Treatment of rhFL expressed from Pichia pastoris resulted in an antitumor response against EL-4 and C26 tumors injected in syngeneic mice.

Adenocarcinoma↗

PubMed2005

[Assembly of apoptin gene using oligodeoxyribonucleotides in vitro].

OBJECTIVE: To explore the method for in vitro gene assembly of apoptin-encoding DNA sequence, for instance, using a large number of oligodeoxyribonucleotides (oligos). METHODS: Based on the encoding sequence of apoptin gene (GeneBank accession number AY171617), a number of oligos were designed to assembly apoptin gene in pfu mix reaction system, and each oligo was 40 nucleotides (nt) in length, in which synonymous codon substitution was used to eliminate the restriction enzyme sites of Bgl II ( position 172, agatct-agatcc) and Hind III (position 306, aagctt-aatcct). The assembly mixture was further diluted and amplified with two end oligos. The targeting sequence was gel-purified, amplified for one more time, followed by the addition of T to the 3' end in the presence of Taq polymerase and dATP before cloning into pGEM-T easy vector. The positive clones were confirmed by restriction enzyme digestion and sequence analysis. RESULTS: The synthetic mixture presented obvious "tails" in the first PCR for assembly. After dilution of the mixture and amplification with two end oligos, clear DNA ladder bands with a clear targeted band were yielded. After PCR, the targeted gene was cloned into pGEM-T easy vector, and the positive clones were confirmed by sequence analysis with be identical to the designed coding sequence of apoptin gene. CONCLUSION: Gene assembly is a rapid and cost-effective approach for synthesis of genes or vectors, which allows simultaneous mutagenesis of several genes in vitro.

Base Sequence↗

PubMed2005

[Experiment study on the estrogen-like effect of compounds of mercury, chromium and manganese].

OBJECTIVE: In order to study estrogen-like effect of compounds of Mercury, Chromium and Manganese. METHODS: Mercury Chloride, Manganese Sulfate, Chromium Chloride and Chromium trioxide were selected to perform proliferation assay of MCF-7 human breast cancer cells and binding assay of estrogen receptor for rat uterine. RESULTS: Mercury Chloride could stimulate the proliferation of MCF-7 cell, the maximal increase of MCF-7 cells was measured by Mercury Chloride at 10(-7) mol/L. The effect was blocked completely by a pure antigestrogen ICI182, 780; but Mercury Chloride could not bind to ER by competing with E2. Chromium Chloride, Chromium Trioxide and Manganese Sulfate were not able to stimulate the proliferation of MCF-7 cell and bind to ER through competing against 3H-E2 in vitro. CONCLUSION: Mercury Chloride exhibited the estrogenicity through binding and activating ER; Chromium Chloride, Chromium trioxide and Manganese Sulfate did not show any estrogenicity.

Animals↗

PubMed2005

[Research on gene expression data based on clustering/classification technology].

As the work of sequencing the genome of the human and many model organisms has been partially or fully finished, the "postgenomic era" has begun. Scientists are turning their focus toward identifying gene function from sequencing. Clustering technology, as one of the important tools of analyzing gene expression data and identifying gene function, has been used widely. In this paper we discuss main clustering technology about gene expression data at present, analyze their advantages and disadvantages, present the methods to solve the problems and give new approaches to study gene expression data.

Algorithms↗

PubMed2004

A novel method for preparation of tissue microarray.

AIM: To improve the technique of tissue microarray (tissue chip). METHODS: A new tissue microarraying method was invented with a common microscope installed with a special holing needle, a sampling needle, and a special box fixing paraffin blocks on the microscope slide carrier. With the movement of microscope tube and objective stage on vertical and cross dimensions respectively, the holing procedure on the recipient paraffin blocks and sampling procedure of core tissue biopsies taken from the donor blocks were performed with the refitted microscope on the same platform. The precise observation and localization of representative regions in the donor blocks were also performed with the microscope equipped with a stereoscope. RESULTS: Highly-qualified tissue chips of colorectal tumors were produced by a new method, which simplified the conventional microarraying procedure, and was more convenient and accurate than that employing the existing tissue microarraying instruments. CONCLUSION: Using the refitted common microscope to produce tissue microarray is a simple, reliable, cost-effective and well-applicable technique.

Colorectal Neoplasms↗

PubMed2004

[Expression of human HSF in E. coli and its effects on mobilization of hematopoietic stem cells in rhesus monkeys].

OBJECTIVE: To study the expression of hHSF in E. coli and its effect on the mobilization of hematopoietic stem/progenitor cells. METHODS: The hHSF gene was obtained by overlapping PCR and cloned into the vector pET30a to yield pET30a-hHSF, which was transformed into E. coli BL21(DE3) and expressed with IPTG induction. Subsequently, rhHSF was purified by gel filtration and cation exchange chromatography and subjected to refolding. Molecular weight of hHSF was measured by MALDI-TOF Mass Spectroscopy. The N terminal amino acid sequence rhHSF was determined by protein sequencing. rhHSF was profiled in rhesus monkey for mobilization of peripheral blood stem cells. Eight rhesus monkeys were equally divided into two groups. The first group was administered single subcutaneous injection of 500 microg/kg hHSF, while the other one was administered 10 microg.kg(-1).d(-1) G-CSF for 4 days followed by a single subcutaneous injection of 500 microg/kg rhHSF. RESULTS: The sequence coding hHSF was confirmed by sequencing and the induced-expression level was about 30% of total cell proteins. The purity of target protein was over 95%. The sequence of N terminal 10 amino acids and the amino acid composition were consistent with the theoretical parameters; molecular weight of rhHSF was 7540. The peripheral CD34(+) cells, CFU-GM yields, and neutrophils peaked at 3 h (16.3-folds increase compared with baseline), 1 h (1.9-folds increase) and 45 min (4.4-folds increase) respectively after the single injection of rhHSF. The addition of rhHSF after the last dose of G-CSF boosted these levels to 25.8-folds, 8.7-folds and 8.3-folds respectively. CONCLUSION: hHSF is highly expressed in E. coli and rapidly mobilizes the hematopoietic stem/progenitor cells and neutrophils in rhesus monkeys. hHSF shows distinct synergistic effect with G-CSF.

Animals↗

PubMed2003

Contribution of eIF-4E inhibition to the expression and activity of heparanase in human colon adenocarcinoma cell line: LS-174T.

AIM: Heparanase degrades heparan sulfate proteoglycans (HSPGs) and is a critical mediator of tumor metastasis and angiogenesis. Recently, it has been cloned as a single gene family and found to be a potential target for antimetastasis drugs. However, the molecular basis for the regulation of heparanase expression is still not quite clear. The aim of this study was to determine whether the expression of eukaryotic initiation factor 4E (eIF-4E) correlated with the heparanase level in tumor cells and to explore the correlation between heparanase expression and metastatic potential of LS-174T cells. METHODS: A 20-mer antisense s-oligodeoxynucleotide (asODN) targeted against the translation start site of eIF-4E mRNA was introduced into LS-174T cells by lipid-mediated DNA-transfection. eIF-4E protein and mRNA levels were detected by Western blot analysis and RT-PCR, respectively. Heparanase activity was defined as the ability to degrade high molecular weight (40-100 kDa) radiolabeled HS (heparan sulfate) substrate into low molecular weight (5-15 kDa) HS fragments that could be differentiated by gel filtration chromatography. The invasive potential of tumor cell in vitro was observed by using a Matrigel invasion assay system. RESULTS: The 20-mer asODN against eIF-4E specifically and significantly inhibited eIF-4E expression at both transcriptional and translational levels. As a result, the expression and activity of heparanase were effectively retarded and the decreased activity of heparanase resulted in the decreased invasive potential of LS-174T. CONCLUSION: eIF-4E is involved in the regulation of heparanase production in colon adenocarcinoma cell line LS-174T, and its critical function makes it a particularly interesting target for heparanase regulation. This targeting strategy in antisense chemistry may have practical applications in experimental or clinical anti-metastatic gene therapy of human colorectal carcinoma.

Adenocarcinoma↗

PubMed2003

[A novel method for fabrication of tissue microarray].

BACKGROUND & OBJECTIVE: Tissue chip (tissue microarray, TMA) is one of the most important biochip techniques, just following the gene chip and the protein chip, which is one of the most important functional genomics and proteomics research methods in the post-genomic era. However, the present TMA technology has certain shortcomings, such as lack of advanced instruments, tedious procedure, and low sampling accuracy, etc. This new method was designed to improve the technology of TMA. METHODS: A common microscope was installed with a special holing needle, a sampling needle, and a proper box to fix paraffin blocks on the microscope carrier. With the precise mechanical control of microscope, the holing procedure on the recipient paraffin blocks and sampling procedure of core tissue biopsies were performed with the re-equipped microscope. The precise observation and localization of sampling regions were also performed using the same microscope equipped with a stereoscope. RESULTS: The new method simplified TMA procedure, and the whole process of holing, locating, and sampling was performed with the same instrument on the same platform. The single-use holing and sampling needles were first applied to maintain higher accuracy and to avoid the tissue remains and contamination among different samples. And high-qualified tissue chips of colorectal tumors were produced successfully by the new method. CONCLUSION: Using the re-equipped common microscope to fabricate tissue microarrays is a simple, reliable, cost-effective,and well-applicable technique.

Histocytological Preparation Techniques↗