Biomedical subjects

Shenqi Wang

Publications and source records attributed to Shenqi Wang.

7 recordsLinked to original sources

PubMed2006

Preparation and characterization of magnetic microspheres for the purification of interferon alpha-2b.

Magnetic agarose microspheres (MAMS), magnetic cellulose microspheres (MCMS), and magnetic poly(vinyl alcohol) microspheres (MPVAMS) were prepared by various different preparation methods. MCMS coupled with anti-IFN alpha-2b monoclonal antibodies (mAb) were selected for the purification of interferon alpha-2b (IFN alpha-2b) after performance characterization among microspheres. Parameters of immunomagnetic separation (IMS), including binding mAb, elution behavior, and sample pretreatment conditions, were optimized to improve the purification efficiency of the separation of IFN alpha-2b by MCMS. Size-exclusion HPLC (HPSEC) showed that the IFN alpha-2b was purified from crude cell lysate had an overall purity of 92.9%, while immunological and biological assays showed an activity recovery of 88.5% and specific antiviral activity of 2.7 x 10(8) IU/mg. Identity and molecular mass of purified IFN alpha-2b were confirmed by western blot and matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS) analysis. This study illustrated the favorable separation media which combined desired properties for the development of magnetic separation of biological materials.

Blotting, Western↗

PubMed2006

Effect of PEG spacer on cellulose adsorbent for the removal of low density lipoprotein-cholesterol.

Carboxyl modified PEG spacer was synthesized and linked covalently to cellulose beads. L-lysine ligand was coupled to the spacer and its selective affinity for low-density lipoprotein-cholesterol (LDL-C) was determined. It was found that the adsorption capacity and the efficiency of the ligand for adsorption of LDL-C was increased when PEG spacer was used. Experimental results showed that with the chain length of PEG spacers increased from 1000Da to 6000 Da, the average adsorption capacity of LDL-C was enhanced from 0.242 mg/ml to 0.903 mg/ml. Above results indicate that PEG spacers are conducible to the selective removal of LDL-C from human plasma. In addition, LDL-C adsorbent with PEG spacers has a low adsorption capacity for high-density lipoprotein (HDL-C).

Adsorption↗

PubMed2005

SARS coronavirus 7a protein blocks cell cycle progression at G0/G1 phase via the cyclin D3/pRb pathway.

The genome of severe acute respiratory syndrome-associated coronavirus (SARS-CoV) contains four structural genes that are homologous to genes found in other coronaviruses, and also contains six subgroup-specific open reading frames (ORFs). Expression of one of these subgroup-specific genes, ORF7a, resulted in apoptosis via a caspase-dependent pathway. Here, we observed that transient expression of ORF7a protein fused with myc or GFP tags at its N or C terminus inhibited cell growth and prevented BrdU incorporation in different cultural cells, suggesting that ORF7a expression may regulate cell cycle progression. Analysis by flow cytometry demonstrated that ORF7a expression was associated with blockage of cell cycle progression at G0/G1 phase in HEK 293 cells after 24 to 60 h post-transfection. Similar results were observed in COS-7 and Vero cells. Mutation analysis of ORF7a revealed that the domain spanning aa 44-82 of 7a protein was essential for its cytoplasmic localization and for induction of the cell cycle arrest. After analyzing the cellular proteins involving in regulation of cell cycle progression, we demonstrated that ORF7a expression was correlated with a significant reduction of cyclin D3 level of mRNA transcription and expression, and phosphorylation of retinoblastoma (Rb) protein at ser795 and ser809/811, not with the expression of cyclin D1, D2, cdk4 and cdk6 in HEK 293 cells. These results suggest that the insufficient expression of cyclin D3 may cause a decreased activity of cyclin D/cdk4/6, resulting in the inhibition of Rb phosphorylation. Accumulation of hypo- or non-phosphorylated pRb thus prevents cell cycle progression at G0/G1 phase.

Animals↗

PubMed2004

Immobilization of cholesterol oxidase on cellulose acetate membrane for free cholesterol biosensor development.

This article describes the immobilization of cholesterol oxidase on a cellulose acetate (CA) membrane activated by Sodium periodate, ethylenediamine, and glutaraldehyde etc. The properties of the immobilized enzyme membrane were investigated. The factors affecting the activity of immobilized enzyme such as the concentration of glutaraldehyde, the concentration of enzyme used during immobilization, temperature, pH, and immobilizing time etc. were also studied. The immobilized COD membrane has been used to construct fibre-optic fluorescent biosensor.

Biosensing Techniques↗

PubMed2003

In vitro, in vivo studies of a new amphiphilic adsorbent for the removal of low-density lipoprotein.

A new amphiphilic adsorbent for the removal of low-density lipoprotein (LDL) was prepared according to the literature (Artif. Cells Blood Subs., Immob. Biotechnol. 30 (4) (2002) 285). The effects of sulfonation and grafting time of cholesterol on the swelling property of adsorbent were studied. When sulfonation and grafting time of cholesterol was 3 and 5 h, respectively, the amphiphilic adsorbent had a high adsorption capacity for LDL without significantly adsorbing high-density lipoprotein. The adsorption capacity of the adsorbent for the removal of LDL, total cholesterol (TC) and TG was 1.916, 2.132, 1.349 mg/ml, respectively. Hyperlipidemia rabbits were developed by feeding with fodder containing high content of cholesterol or yolk, which was then perfused with an optimal amount of amphiphilic adsorbent. After 2 h hemoperfusion, the LDL levels decreased from 3.619+/-0.354 to 0.724+/-0.07 mmol/l, which showed that the adsorbent could effectively remove LDL without side effect.

Adsorption↗

PubMed2003

A novel amphiphilic adsorbent for the removal of low-density lipoprotein.

Dextran adsorbent with amphiphilic ligands for adsorption of low-density lipoprotein (LDL) was prepared by the following procedures. Cholesterol group was linked to Dextran G 75 by reacting with cholesterol N-(6-isocyanatohexyl) carbamate in the presence of pyridine in DMSO at 80. In order to introduce the hydrophilic moiety, it was then reacted with chlorosulfonic acid in formamide which introduced the sulfonic group. Adsorption capacity of the adsorbent was studied which showed the removal of LDL-cholesterol (LDL-C), total cholesterol (TC) and TG to be 1.916, 2.132 and 1.349 mg/ml, respectively without significantly affecting total protein levels in the plasma. Moreover, the adsorbent has a better selectivity in removing LDL-C, TC, TG compared to dextran which has only hydrophobic or hydrophilic ligand.

Adsorption↗

PubMed2002

MProbe: computer aided probe design for oligonucleotide microarrays.

The present work describes a complete probe design software system for oligonucleotide microarrays based on Kane's research on probe sensitivity and specificity (Kane's rule). Combining Kane's rule and traditional criteria for probe design we constructed MProbe, the software system for oligonucleotide microarrays using Java. The general criteria for probe design are: (1) probes may have different lengths that range from 20 to 100 bases; (2) they should have a similar melting temperature (Tm) or GC content; (3) they should not contain stable secondary structures; and (4) they abide by Kane's rule.

Computational Biology↗