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Biomedical subjects

Guanghui Wang

Publications and source records attributed to Guanghui Wang.

25 records · Page 2Linked to original sources
PubMed2005

Proteolysis of macrophage inflammatory protein-1alpha isoforms LD78beta and LD78alpha by neutrophil-derived serine proteases.

Macrophage inflammatory protein-1alpha (MIP-1alpha) is a chemokine that leads to leukocyte recruitment and activation at sites of infection. Controlling chemokine activity at sites of infection is important, since excess accumulation of leukocytes may contribute to localized tissue damage. Neutrophil-derived serine proteases modulate the bioactivity of chemokine and cytokine networks through proteolytic cleavage. Because MIP-1alpha is temporally expressed with neutrophils at sites of infection, we examined proteolysis of MIP-1alpha in vitro by the neutrophil-derived serine proteases: cathepsin G, elastase, and proteinase 3. Recombinant human MIP-1alpha isoforms LD78beta and LD78alpha were expressed and purified, and the protease cleavage sites were analyzed by mass spectrometry and peptide sequencing. Chemotactic activities of parent and cleavage molecules were also compared. Both LD78beta and LD78alpha were cleaved by neutrophil lysates at Thr16-Ser17, Phe24-Ile25, Tyr28-Phe29, and Thr31-Ser32. This degradation was inhibited by serine protease inhibitors phenylmethylsulfonyl fluoride and 4-(2-aminoethyl)-benzenesulfonyl fluoride. Incubation of the substrates with individual proteases revealed that cathepsin G preferentially cleaved at Phe24-Ile25 and Tyr28-Phe29, whereas elastase and proteinase 3 cleaved at Thr16-Ser17 and Thr31-Ser32. Proteolysis of LD78beta resulted in loss of chemotactic activity. The role of these proteases in LD78beta and LD78alpha degradation was confirmed by incubation with neutrophil lysates from Papillon-Lefevre syndrome patients, demonstrating that the cell lysates containing inactivated serine proteases could not degrade LD78beta and LD78alpha. These findings suggest that severe periodontal tissue destruction in Papillon-Lefevre syndrome may be related to excess accumulation of LD78beta and LD78alpha and dysregulation of the microbial-induced inflammatory response in the periodontium.

Amino Acid Sequence↗
PubMed2005

[In vitro study of the directed inducing cartilage cells from rat bone mesenchymal stem cells on scaffolds].

This study was conducted to assess the cell proliferation and cell cycle of the directed inducing cartilage cells from rat bone mesenchymal stem cells on collagen sponge and compare the results with those of the plane inducing cartilage cells. The MSCs were isolated from rat bone marrow by density gradient centrifuge and adhesive property, and then were induced into chondrogenic differentiation by adding transforming growth factor-beta1 (TGF-beta1), dexamethasone, transferring and insulin on collage sponge and plane condition. Immunohistochemistry was applied to detect the expression of collagen type II on the scaffolds and plane conditions. The cell proliferation and cell cycle on different conditions were detected with MTT automated colormetric microassay and flow cytometry. The differentiation of MSCs toward chondrogenic phenotype was verified by the positive result of collagen type II on the scaffolds and plane condition. The cell viability in scaffolds was better than that in plane conditions. The S phase and G2 phase were 30 percent in whole cell cycle on the scaffold, which was different from that of the control groups. The method of using the Using directed inducing cartilage from bone MSCs combined with collage sponge to construct tissue-engineered cartilage is feasible; it is better than the method of plane directed inducing.

Animals↗
PubMed2003

Global protein identification and quantification technology using two-dimensional liquid chromatography nanospray mass spectrometry.

A simple and reliable method is described here for the identification and relative quantification of proteins in complex mixtures using two-dimensional liquid chromatography/tandem mass spectrometry. The method is based on the classical proteomic analysis where proteins are digested with trypsin and the resulting peptides are separated by multidimensional liquid chromatography. The separated peptides are analyzed by tandem mass spectrometry and identified via a database search algorithm such as SEQUEST. The peak areas (integrated ion counts over the peptide elution time) of all identified peptides are calculated, and the relative concentration of each protein is determined by comparing the peak areas of all peptides from that protein in one sample versus those from the other. Using this strategy, we compared the relative level of protein expression of A431 cells (an epidermal cell line) grown in the presence or absence of epidermal growth factor (EGF). Our results are consistent with the published observations of the transient effects of EGF. In addition, the difference in the concentrations of several phosphopeptides determined in our studies suggests the possibility of several new targets involved in the EGF cell-signaling pathway. This global protein identification and quantification technology should prove to be a valuable means for comparing proteomes in biological samples subjected to differential treatments.

Amino Acid Sequence↗
PubMed2003

A new method to improve sensitivity and resolution in matrix-assisted laser desorption/ionization time of flight mass spectrometry.

High detection sensitivity and resolution are two critical parameters for recording good peptide mass fingerprints (PMF) of low abundance proteins. This paper reports a mass spectrometry (MS) sample preparation technique that could improve sensitivity and resolution. By coating the MS steel target with a thin layer of pentadecafluorooctamido propyltrimethoxysilane, which was both polar and nonpolar solvent repellent, the transferred sample droplets on its surface were significantly smaller. As a result, the analyte of the peptide mixture became more concentrated and homogeneous, which helped to improve the sensitivity. The advantages of a modified MS target were documented by mass spectra improvement of attomole level standard peptides and silver-stained proteins from polyacrylamide gels. The mass signal of angiotensin II at 100 attomole was difficult to record on the conventional support, whereas it was easily detected on the modified one. The PMF of cytochrome C was also better recorded on the modified support, in terms of both signal-to-noise ratio and the number of detected peptides. When silver-stained proteins from two-dimensional electrophoresis gels were analyzed, in most cases more satisfactory peptide mass spectra were obtained from the modified support. Searching protein databases with more mass data from the improved PMFs, several unknown proteins were successfully identified.

Angiotensin II↗
PubMed2003

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry studies of low molecular weight dendrimers.

We report the application of matrix-assisted laser desorption/ionization time-of-flight (MALDI-ToF) mass spectrometry, with delayed extraction in the reflectron mode, for the characterization of low molecular weight dendrimers. 20 dendrimer samples were measured and 4 typical dendrimers, as examples, are discussed in detail. Several factors that affect the analysis including the matrices used, the concentrations of sample, the solvents and cationization reagent used, were investigated in detail. Experimental results indicate that the type of solvent can greatly influence exact mass measurement. However, sample preparation is generally not very critical for dendrimer analysis using MALDI-ToF since many kinds of matrices and a wide range of sample concentrations can be used efficiently. In addition, the Cs(+) ion can be used to enhance the efficiency of cationization. Some reasons for this behavior are discussed on the basis of results of calculations using Gaussian94 software (a connected system of programs for performing a variety of semi-empirical and ab initio molecular orbital (MO) calculations).

Journal Article↗
PubMed2003

[Expression of oncogene C-jun in the cells of rat nasal mucosa and relevance with rhinorrhea].

OBJECTIVE: To study the expression of oncogene C-jun in rat nasal mucosa with allergic rhinitis and the relevance with rhinorrhea. METHOD: By using EA to make animal model of allergic rhinitis successfully; the amount of rhinorrhea was calculated at 30 min. 4 h, 8 h. Immunohistochemical technique, computer image analysis technique and histologic examination were used to investigated the expression of C-jun in rat nasal mucosa at the same time. The relevance between them was used explored. RESULT: There was a lot of C-jun protein at 30 min. The difference of C-jun between 30 min group and control group was significant (P < 0.01) and the relevant coefficient was r = 0.784 (P < 0.05). The C-jun protein decreased at 4 h, but there was still significant difference (P < 0.05) and r = 0.626 (P < 0.05). The C-jun was as same as control group at 8 h, There was no difference between them. CONCLUSION: The expression of oncogene C-jun in inflammatory cells may be a marker in early stage of activation of inflammatory cells, and related to the producing and secreting of cytokines and inflammatory mediators in inflammatory cells of allergic rhinitis.

Animals↗