Biomedical subjects

Yong-sheng Wang

Publications and source records attributed to Yong-sheng Wang.

At least 19 recordsLinked to original sources

PubMed2006

Preparation of roxithromycin-polymeric microspheres by the emulsion solvent diffusion method for taste masking.

Microspheres of roxithromycin with Eudragit S100 and silica were prepared by the emulsion solvent diffusion method to mask the bitter taste of the antibiotic. The effect of different polymers and drug-polymer ratios on the taste masking and the characteristics of the microspheres were investigated. It was found that Eudragit S100 was the best for masking the unpleasant taste of roxithromycin among the six kinds of polymers investigated. The results of DSC, X-ray diffraction and IR showed that there were several combinations of roxithromycin and Eudragit S100. The influence of other formulation factors, i.e. dichloromethane-acetone ratios and silica-polymer ratios on the properties of the microspheres were also examined. In conclusion, the results of the present study will be helpful for the preparation of oral forms of roxithromycin with an acceptable taste.

Acetone↗

PubMed2006

Study of the preparation of sustained-release microspheres containing zedoary turmeric oil by the emulsion-solvent-diffusion method and evaluation of the self-emulsification and bioavailability of the oil.

The purpose of this study was to design a sustained-release formulation of an oily drug. The sustained-release microspheres with self-emulsifying capability containing zedoary turmeric oil (ZTO) were prepared by the quasi-emulsion-solvent-diffusion method. The micromeritic properties, the efficiency of emulsification and the drug-release behavior of the resultant microspheres were investigated. The bioavailability of the microspheres was compared with conventional ZTO self-emulsifying formulations for oral administration using 12 healthy rabbits. An HPLC method was employed to determine the concentration of germacrone in plasma, which was used as an index of ZTO. Spherical and compacted microspheres with average diameters of 100-600 microm have been prepared, and their release behavior in distilled water containing 1.2% (w/v) of polysorbate-80 can be controlled by the ratio of polymer/Areosil200 in the microspheres. The resultant emulsions with mean droplet sizes of 200-500 nm are produced when the microspheres are immersed in phosphate buffer (pH 6.8) under gentle agitation. The stability and the droplet size of the resultant emulsions are also affected by the polymer/Areosil200 ratio in the formulation, while the amount of talc has a marked effect on the self-emulsifying rate. The plasma concentration-time profiles with improved sustained-release characteristics were achieved after oral administration of the microspheres with a bioavailability of 135.6% with respect to the conventional self-emulsifying formulation (a good strategy for improving the bioavailability of an oily drug). In conclusion, the sustained-release microspheres with self-emulsifying capability containing ZTO have an improved oral bioavailability. Our study offers an alternative method for designing sustained-release preparations of oily drugs.

Administration, Oral↗

PubMed2006

Expression of extracellular domain of human vascular endothelial growth factor receptor-2 in Pichia pastoris.

OBJECTIVE: To investigate the feasibility of high expressing extracellular domain of human vascular endothelial growth factor receptor-2 (heVEGFR-2) with eukaryotic protein structure in Pichia pastoris. METHODS: We used PCR to amplify the DNA fragment encoding heVEGFR-2 from pORF-heVEGFR-2. The recombinant Pichia pastoris secretory expression vector(pPICZalphaA-heVEGFR-2)was constructed and transferred into Pichia pastoris X-33 by electroporation. The high expression transformnants were identified through its drug-resistant phenotype and methanol induction. RESULTS: As indicated by SDS-PAGE, the recombinant heVEGFR-2 protein with a molecular weight (MW) approximately 108 kDa, which reached 80 mg/L in the mass concentration, comprised 45% of the total expressed secreted proteins from Pichia pastoris X-33. The section of heVEGFR-2 had a MW approximately 106 kDa. The results of western blot analysis demonstrated that this protein could be specifically recognized by the rat monoclonal antibody against mouse VEGFR-2 (rat McAb against mVEGFR-2). CONCLUSION: The heVEGFR-2 with eukaryotic protein structure can get a high expression in Pichia pastoris.

Animals↗

PubMed2006

[The antiangiogenic effect of DNA vaccine based on beta-defensin 2 fused with VE-cadherin].

OBJECTIVE: To explore the feasibility of generating beta defensin 2 fusion vaccine to break the immune tolerance of self antigens associated with angiogenesis. METHODS: PCR amplification of mature beta defensin 2 (Def) and extracelluar segment of Vascular Endothelial Cadherin (Cad) was conducted. (GGGS)3 was used as linker peptide for fusion plasmid(Def-Cad). All the three segments were inserted into pSecTag2B plasmid (pSec), and CT26 tumor cells were transfected. Expression was verified by RT-PCR and chemotaxis assay. The alginate bead model was used to study the antiangiogenic effect of fusion plasmid vaccination. RESULTS: All constructions were verified by sequencing and were found expressed in mammalian cell. The beta defensin 2 fusion protein had similar capacity to chemoattract dendritic cells as compared with nonfusion protein (P>0.05). The alginate bead assay revealed that the tumor-induced angiogenesis in fusion plasmid immunized mice was significantly suppressed when compared with that in nonfusion plasmid (P<0.01). CONCLUSION: An active immunization strategy based on beta defensin 2 fused with angiogenesis related antigen of endothelial can inhibit angiogenesis and may be a useful approach for cancer therapy.

Angiogenesis Inhibitors↗

PubMed2006

[Spectral properties of energy transfer in doubly doped polymer electroluminescence].

The authors report a cascade energy transfer based on the long-range dipole-dipole Förster energy transfer between polymer and two fluorescent dyes in solid thin films. The authors studied the fabrication and emission characteristics of a new doubly doped system for color purity and energy transfer efficiency, in which two fluorescent dyes, i. e. TPB and Rubrene were doped into PVK. In the blend film, PVK acted as the energy donor, Rubrene as the fluorescent dye, and the assistant dopant TPB was used to facilitate the energy transfer from PVK to the dye Rubrene. Orange emission comes from Rubrene via a cascade energy transfer from PVK toTPB and then from TPB to Rubrene.

English Abstract↗

PubMed2006

[Photostimulated luminescence and optical storage of BaLiF3:Eu2+].

BaLiF3:Eu2+ was prepared by high temperature solid state reaction. The peaks of photoluminescence spectrum and photostimulated luminescence (PSL) spectrum are both at 410 nm which are attributed to the 5d-4f emission of Eu2+. The photostimulated luminescence excitation spectrum has its maximum at about 660 nm. Therefore, He-Ne laser is suitable for the reading-out process. The mechanism of PSL was also studied according to the characters of the spectra in the present paper. The PSL decay property of the glass ceramics was investigated, and it was shown that the storage information is easy to be erased. BaLiF3:Eu2+ has good properties of PSL and a promising future.

English Abstract↗

PubMed2006

[Study of luminescence properties of nano-size ZnO embedded in SiO2 layer grown by radio-frequency magnetron sputtering].

Nano-size ZnO embedded in SiO2 layers were grown by radio-frequency magnetron sputtering. Absorption spectra and PL spectra were employed to study the optical character of the samples at room temperature. Absorption spectra blue-shifted when the size of nano-meter ZnO decreased, which indicated that quantum size effect became stronger with decreasing the size of ZnO. PL spectra show two peaks at about 387 and 441 nm, respectively. It was concluded that the UV emission originates from the radiative recombination of free-exciton, and the blue emission is due to the electron transition from donor levels of oxygen vacancies to the top of valence band. The origin of the two peaks is demonstrated by time-resolved spectra and luminescence decay curve.

English Abstract↗

PubMed2006

[The influence of holes buffer layer doped with different one-dimensional nanomaterials on the performance of polymer light-emitting diodes].

The effect of holes buffer layer PEDOT doped with one-dimensional nanomaterials on the performance of polymer light-emitting diodes was investigated. The photoluminescence efficiency of double layer sample PEDOT/MEH-PPV was enhanced by doping one-dimensional nanomaterials (TiO2 nanotube and ZnO nanorod) into PEDOT layer. Stronger interaction of one-dimensional nanomaterials and PEDOT suppressed the creation of defect states which can quench radiative recombination of excitons. The electroluminescence efficiency of device was improved by 2 and 2.5 folds by doping TiO2 nanotubes and ZnO nanorods into holes buffer layer PEDOT respectively.

English Abstract↗

PubMed2006

[Expression and characterization of mouse 17-1A antigen from Pichia pastoris].

OBJECTIVE: This is a ground work in preparation for the development of a vaccine against tumor, in which 17-1A glucoprotein, a tumor associated antigen (TAA), was cloned and expressed in Pichia pastoris. METHODS: The cDNA of 17-1A gene was cloned from nephridial tissue of mouse embryo by RT-PCR and subsequently inserted into pPICZaA plasmid after digestion with Xho I and Xba I. The linearized recombinant plasmid was transformed into Pichia pastoris strain GS115. 17-1A glucoproteins were secreted into culture supernatant through alpha-signal peptide of AOX I after inducation with methanol. The protein products were analyzed and characterized by SDS-PAGE and Western-blot. RESULTS: The plasmid pPICZalphaA-17-1A was constructed and verified by sequenceing. 17-1A glucoproteins were expressed stably and glycosylated in Pichia pastoris. CONCLUSION: Glycosylated tumor associated antigen 17-1A can be expressed in Pichia pastoris.

Animals↗

PubMed2006

[The influence of frequency on solid state cathodoluminescence].

Solid state cathodoluminescence (SSCL) is a new mechanism of light emission in organic-inorganic system. In the present article, we get SSCL under sinusoidal alternating-current voltage with a structure of ITO/SiO2/MEH-PPV/SiO2/Al. The spectra have two peaks: 410 and 580 nm, which obey molecular theory and band model, respectively. The temporal behaviors of both peaks in SSCL are studied with a new method of estimating lifetime in frequency domain. The intensity of the peak at 410 nm decreases as the frequency of the driving voltage increases, and the intensity of the peak at 580 nm increases as the frequency of the driving voltage increases. The difference in the dependence of light intensity on the frequency of excitation comes from the difference in the lifetime of the two peaks. The lifetime of short wavelength emission is found to be less than 5 ms while that of long wavelength emission is more than 0.05 ms.

English Abstract↗

PubMed2006

[The change in optical spectra from solid and liquid solution of copper phthalocyanines derivatives].

In the present work, the change in electronic absorption spectra from three copper phthalocyanines (CuPc, tb-CuPc, oo-CuPc) in different environments was investigated. The mechanism of red shift Q-band absorption from the three species in an organic solvent before and after protonation was discussed. This was used to compare with those dispersed in solid films. The relation between the molecular interactions and the spectra change was studied. In a combination of POM, DSC and XRD techniques, the structure and morphology of the thin films were characterised. It was found that the molecules in the doped matrices of PC were associated or aggregated. This association and hence the corresponding change in absorption spectra cannot be altered by the modification of dopant concentration.

English Abstract↗

PubMed2005

[A study on the ultraviolet spectra of halogenated benzoylferrocenes].

The ultraviolet spectra of all of the o, m, p-halogenated benzoylferrocenes have been studied the following rules obtained: 1. The lambdamax of the ultraviolet spectrum R band and K band for the isomers is lambdamax(m-X) > lambdamax(p-X) > lambdamax(o-X). 2. With the same substituted positions of the different halogen on the benzene ring, the lambdamax of the ultraviolet spectrum K band is lambdamax(C1) > lambdamax(Br) > lambdamax(I) > lambdamax(F), then, the lambdamax of ultraviolet spectrum R band is lambdamax(I) > lambdamax(Br) > lambdamax(Cl) > lambdamax(F).

Benzene↗

PubMed2005

[Determination of cholesteryl palmitate in Oviductus Ranae by HPLC].

OBJECTIVE: To develop a new method for the determination of cholesteryl palmitate in Oviductus Ranae. METHOD: A HPLC method was set up, using Zorbax Silica column and cyclohexane-diethyl ether (40:1) as mobile phase with a flow rate of 1.0 mL x min(-1), and the UV detection wavelength was 203 nm. RESULT: The calibration curve was linear over the range of 0.60-8.92 microg (r = 0.9997), the average recovery of the method was 98.4%. RSD 1.8% (n = 6). CONCLUSION: The results showed that method was reliable and accurate.

Animals↗

PubMed2005

[Infrared photostimulated luminescence and optical storage compares in alkaline earth sulphide doped with Mn].

The phosphors SrS: Eu and CaS: Eu doped with Mn were prepared by sulfurization flux method (SFM). Infrared photostimulated luminescence (PSL) of both the phosphors were measured. The PSL peak wavelength of SrS: Eu, Mn is 610 nm. Comparing the storage intensities, SrS has better optical properties. The doping of Mn2+ increases photon amount and improves the storage properties.

Calcium Compounds↗

PubMed2005

[Photostimulated luminescence properties of KCl:Cu+ after UV excitation].

KCl:Cu+ powder sample was prepared with high temperature solid reaction process. After being excited by UV, the sample shows near ultraviolet blue luminescence by stimulation with 560 nm light. The research result indicates that Cu+ acts as a luminous center, and Cu+ does not change into Cu2+ by UV irradiation. So, Cu+ ions do not act as hole traps, while anion vacancies act as electron traps. Once UV excited sample is stimulated, electrons from F center combine with hole trapping center or VK center, and cause subsequent energy transfer to Cu+ ion. Then, a character emission attributed to d-s transition of Cu+ in lattice occurs.

English Abstract↗

PubMed2005

[Study of OSL property of electron trapping material with differential absorption spectra].

A method, which makes use of difference of absorption in different stages of excitation process, is introduced to get more information about optical stimulated luminescence (OSL) properties of electron trapping materials (ETM). Absorption spectra of excited ETM contain all absorption of various traps (defects) together. So, the difference between absorption spectra before and after excitation (differential absorption) not only acts as the same as stimulation spectra, but also provides more information, such as holes stimulation, total volume of optical storage, etc. This method is helpful in studying OSL properties.

English Abstract↗

PubMed2004

[Electroluminescence property of MEH-PPV/ZnO nano-crystal structure].

A new structure with II-VI nano-crystal ZnO film as the electron transport layer and MEH-PPV as the hole transport layer and emitting layer was fabricated. The new structure's brightness and efficiency were improved markedly compared with that of the single MEH-PPV layer structure. And a new peak at 620 nm was found in the ITO/MEH-PPV/ZnO/Al structure's electroluminescence spectrum, which should resulted from ZnO layer. In addition, the turning-on voltage of the two-layer structure decreased from 9 V of the single layer structure to 4 V. From the I-V curve, the authors concluded that the emitting area was around the interface of MEH-PPV/ZnO and the combination area could shift with changing the voltage.

English Abstract↗

PubMed2004

[Determination of deoxyribonucleic acids at nanograms levels with toluidine blue by a resonance light-scattering method].

Resonance light scattering (RLS) spectra of toluidine blue (TB) with DNA was studied. The RLS of TB was greatly enhanced by DNA in the range of pH 10-11. A RLS peak at 350 nm was found, and the enhanced intensity of RLS at this wavelength was proportional to the concentration of DNA. The linear range of the calibration curve was 0-900 ng x mL(-1) with the detection limit of 6.75 ng x mL(-1) for the ctDNA, and for fsDNA the linear range was 0-900 ng x mL(-1) with the detection limit of 2.99 ng x mL(-1). Precision at 500 ng x mL(-1) for the two nucleic acids was 3.7% and 5.6%, respectively. Four synthetic samples were determined satisfactorily.

Calibration↗