Biomedical subjects

Mingyuan Li

Publications and source records attributed to Mingyuan Li.

10 recordsLinked to original sources

PubMed2007

Synthesis and characterization of biocompatible Fe3O4 nanoparticles.

In this study, magnetite (Fe3O4) nanoparticles with a size range of 8-20 nm were prepared by the modified controlled chemical coprecipitation method from the solution of ferrous/ferric mixed salt-solution in alkaline medium. In the process, two kinds of surfactant (sodium oleate and polyethylene glycol) were studied; then, sodium oleate was chosen as the apt surfactant to attain ultrafine, nearly spherical and well-dispersed (water-base) Fe3O4 nanoparticles, which had well magnetic properties. The size and size distribution of nanoparticles were determined by particle size analyzer. And the magnetite nanoparticles was characterized by X-ray powder diffraction (XRD) analysis, transmission electron microscopy (TEM), electron diffraction (ED) photography, Fourier transform infrared spectrometer (FT-IR), and vibrating-sample magnetometer (VSM). Also the effect of many parameters on the Fe3O4 nanoparticles was studied, such as reaction temperature, pH of the solution, stirring rate and concentration of sodium oleate. And the 5-dimethylthiazol-2-yl-2,5- diphenyltetrazolium bromide (MTT) assay was performed to evaluate the biocompatibility of magnetite nanoparticles. The results showed that the Fe3O4 nanoparticles coated by sodium oleate had a better biocompatibility, better magnetic properties, easier washing, lower cost, and better dispersion than the magnetite nanoparticles coated by PEG.

3T3 Cells↗

PubMed2006

Construction of eukaryotic expressing plasmids encoding HA and HA1 of influenza A virus and their transient expression in HEK293 cells.

In order to explore the feasibility and protective efficiency of influenza DNA vaccine, we constructed eukaryotic expressing plasmids encoding HA and HA1 of influenza A virus (A/PR/8/34) and studied their expression in HEK293 cells. HA and HA1 genes were amplified by RT-PCR and cloned into pcDNA3.1(+) to generate pcDNA3.1(+)/HA and pcDNA3.1(+)/HA1, respectively. After verification of the cloning fidelity by restriction endonuclease digestion, PCR, and sequencing, pcDNA3.1(+)/HA and pcDNA3.1(+)/HA1 were transfected into HEK293 cells using PolyFect Transfection Reagent. Immunofluorescence assay was used to detect the transient expressing cells. Fluorescence microscopy revealed strong expression of target gene in HEK293 cells transiently transfected with either pcDNA3.1(+)/HA or pcDNA3.1(+)/HA1. Therefore, the results confirm the successful construction of eukaryotic expressing plasmids capable of driving the eukaryotic expression of influenza virus antigen HA and HA1, which is likely to provide a basis for both further investigation of the mechanism of influenza viral infection and the development of influenza DNA vaccine.

Cell Line↗

PubMed2006

[Suppression of telomerase activity by plasmid-mediated RNA interference].

This study was aimed to construct a plasmid expressing siRNA specific for the human telomerase reverse transcriptase (hTERT) gene and to evaluate the ability of small interference RNA(siRNA) for inhibiting telomerase activity in HeLa cells. 64 nucleotides, in which 19 nt were homologous with hTERT gene, were chemically synthesized, annealed and linked into pSUPER to get pSUP-hTE. Then pSUP-hTE was digested with enzyme. We obtained its fragmant concluding promoter and 64nt. So we cloned it into pEGFP-C1 for constructing pEGFP-hTE which contains neo gene and the enhanced green fluorescent protein (EGFP). Recombinant pEGFP-hTE was transfected to HeLa cells. These cells were screened with medium containing G418. When stable colonies appeared, G418-resistant cells were harvested and propagated. At the different cell generations, hTERT mRNA and protein expression, telomerase activity and cell growth activity were analyzed. Compared with control cells, HeLa cells transfected with pEGFP-hTE showed that hTERT mRNA level and hTERT protein expression decreased and telomerase activity reduced by 38%, but the cells growth activity displayed no changes. So pEGFP-hTE could specifically inhibit expression of hTERT and telomerase activity. These results suggested that siRNA targeting hTERT gene might provide a new strategy for cancer biotherapy.

Base Sequence↗

PubMed2005

[Characterization of anticoagulant biomaterial and its development].

Good anticoagulant biomaterials need good surface chemical properties, good mechanics performances and particularly good characteristics of biocompatibility, including tissue compatibility and hemocompatibility. In order to understand with greater clearness the anticoagulant biomaterial, we have to characterize them by different methods. In this paper, the approaches to assessing and displaying the characteristics of anticoagulant biomaterial are reviewed in three aspects, namely the surface chemical properties and structure, the mechanics performances the and the biocompatibility of anticoagulant biomaterial.

Anticoagulants↗

PubMed2004

Creation of a transgenic mouse for hair-cell gene targeting by using a modified bacterial artificial chromosome containing Prestin.

We made a transgenic mouse that expresses Cre recombinase activity in inner ear hair cells by using a modified bacterial artificial chromosome containing Prestin. Cre recombinase activity was restricted to inner and outer hair cells, a subset of vestibular hair cells, spiral and vestibular ganglia in the inner ear, and a subset of cells in the testis, epididymis, and ear bone. This mouse will be useful for hair-cell-specific gene targeting.

Animals↗

PubMed2004

Inner hair cell Cre-expressing transgenic mouse.

Cochlear hair cells of the inner ear are mechanosensory transducers critical for sound reception in mammals. A mouse with a specific expression of Cre recombinase activity in hair cells is essential for hair cell-specific gene targeting. Here we report a transgenic mouse in which Cre activity is detected in inner hair cells, not in supporting cells, in the cochlea. The Cre activity was visualized with both X-gal staining and beta-galactosidase immunostaining in progeny of a cross between our Cre line and the reporter ROSA26R line. In inner hair cells, the Cre activity started at postnatal day 14 and was maintained throughout adulthood. Starting at postnatal day 50, a few outer hair cells in the outermost row of cochlear apical and middle turns displayed the Cre activity. In vestibular hair cells and spiral ganglia, the Cre activity was also detected. Cre activity was present in cells widely distributed throughout brain, testis, and retina, but was absent in many other tissues such as kidney, heart, liver, and intestine. This Cre mouse line can thus be used for conditional gene targeting in mature inner hair cells of the cochlea. genesis 39:173-177, 2004.

Animals↗

PubMed2003

[Apoptosis of cancer cells induced by influenza virus and its elementary mechanism].

OBJECTIVE: To study the apotosis-inducing effects of influenza virus on cancer cells and the role of FasL. METHODS: Four strains of cancer cells (Hela, Raji, SMMC-7721 and SPC-A-1) were infected with 20 m. o. i influenza virus and the effects of apoptosis were detected at different time points post infection by electron microscopy, DNA agrose gel electrophoresis, PI stained flow cytometry, and Annexin-V FITC/PI stained flow cytometry. And the concentration of FasL in the culture supernatant was measured with the use of ELISA at the same time. RESULTS: All the four strains of cancer cells showed apoptotic morphological changes. DNA agarose electrophoresis also showed "ladder" in a time dependent manner after virus infection. During this course, there was an obvious increase of FasL concentration in the cell culture supernatant. CONCLUSION: Influenza virus can induce tumour cells apoptosis in vitro, and it is probably related to the increased expression of FasL.

Adenocarcinoma↗

PubMed2003

Apoptosis in Raji cell line induced by influenza A virus.

OBJECTIVE: To study the apoptotic effects of influenza A virus on the Raji cell line. METHODS: Cultured Raji cells were infected with influenza A virus at a multiplicity of infection (m.o.i) of 20 and the effects of apoptosis were detected at different time points post infection using the following methods: electron microscope, DNA agarose gel electrophoresis, PI stained flow cytometry (FCM) and Annexin-V FITC/PI stained FCM. RESULTS: Raji cells infected with influenza A virus showed changes of morphology apoptosis, DNA agarose electrophoresis also demonstrated a ladder-like pattern of DNA fragments in a time-dependent manner. PI stained FCM showed "apoptosis peak" and FITC/PI stained FCM showed apoptotic cells. Quantitative analysis indicated that the percentage of apoptotic Raji cells increased after infection, and cycloheximide (CHX), an eukaryotic transcription inhibitor, could effectively inhibit the apoptotic effects of influenza A virus in vitro. CONCLUSIONS: Influenza A virus can induce apoptosis in Raji cell line suggesting that it may lead to a potential method for tumor therapy.

Apoptosis↗

PubMed2003

[Construction and screening of TsF cDNA library specific for AchR].

OBJECTIVE: To construct the T suppress factor (TsF) cDNA library specific for AchR and screen out the positive clones of TsF. METHODS: The full-length cDNA was synthesized by the reverse transcripting from the TsF PolyA+mRNA, which had been extracted from the AchR specific suppressor lines (ARSL). The cDNA library was obtained using Lambda gt11 vector. Finally, this cDNA library was screened by Western blotting using Analysis of this cDNA library showed that titer of the monoclonal antibody specific for TCR-achain. RESULTS: recombinant bacteriophage was 1.4 x 10(7) pfu/ml, the rate of positive recombinant was 86.9%. The recombinant bacteriophage DNA were digested by EcoRI and electrophoresis analysis found that the main size of insertion was 0.8 to approximately 4.0 kb . As a result of screening, 27 positive clones were obtained. The positive recombinant bacteriophage DNA were digested by EcoRI, and electrophoresis analysis found that the size of insertion was 1 kb. Conclusion The results suggested that this cDNA library is available, the recombination phages can express TsF specific for AchR effectively and could be used to prepare the products of gene engineering of TsF.

Animals↗

PubMed2002

Influence of demulsifiers of different structures on interfacial dilational properties of an oil-water interface containing surface-active fractions from crude oil.

The influences of two commercial demulsifiers that have a straight chain and branch chain, respectively, on the dilational viscoelasticity of an oil-water interfacial film containing surface-active fractions from crude oil were investigated. The branch-chain demulsifier AE-121 could efficiently substitute surface-active fractions of different average molecular weights from the oil-water interface, while straight-chain SP-169 could only efficiently substitute those of large average molecular weight. It was apt to form a mix-adsorption layer with surface-active fractions of small average molecular weight. The results showed that the molecular size (or represented by average molecular weights) of the surface-active fractions was an important factor influencing the reciprocity of demulsifiers and surface-active fractions at the oil-water interface. This effect could be well explained by the difference between sizes of surface-active fraction molecules and vacancies between demulsifier molecules at the interface. The results of SDBS also proved this explanation.

Journal Article↗