Biomedical subjects

Gang Jin

Publications and source records attributed to Gang Jin.

36 records · Page 2Linked to original sources

PubMed2005

[Clinicopathological study of lymphatic vessel density and distribution in pancreatic cancer].

OBJECTIVE: To clarify the clinicopathological significance of lymphatic vessel density (LVD) and distribution in pancreatic cancer. METHODS: We measured LVD in 43 pancreatic cancer specimens by immunostaining with specific lymphatic endothelium marker, and examined their relationship with well-defined clinicopathological variables. RESULTS: Intratumoral LVD (9.4 +/- 10.0) was significantly lower than periturmoral (16.0 +/- 9.7) (P < 0.001) and nontumoral LVD (13.5 +/- 6.0) (P < 0.01). Increased peritumoral LVD correlated significantly with tumor staging (P < 0.05) and lymph node involvement (P < 0.05). CONCLUSION: The lymphatic vessels distribution in pancreatic cancer samples and peritumoral lymphangiogenesis may promote the malignant progression and lymph node metastasis of pancreatic cancer.

Adenocarcinoma↗

PubMed2005

[Expression and renaturation of a novel human single-chain Fv antibody against SARS-CoV].

A novel human ScFv H12 against SARS-CoV has been selected from a SARS immune library. In order to produce a large amount of ScFv H12, pET28a-H12 expression vector was constructed and ScFv H12 was expressed at yield about 30% of total proteins in E. coli . Here two different refolding procedures were used to refold ScFv H12 from inclusion body: gel filtration chromatography and dilution. The results showed that ScFv H12 could be efficiently refolded by both procedures. However, the refolding via gel filtration was 1.5 time more effective than that of dilution. The affinity of ScFv H12 to SARS-CoV virion was detected as Kd = 73.5 nmol/mL.

Antibodies, Monoclonal↗

PubMed2004

Adsorption of human serum albumin onto gold: a combined electrochemical and ellipsometric study.

Human serum albumin adsorption onto gold surfaces was investigated by electrochemical and ellipsometric methods. Albumin adsorption onto gold was confirmed by the change of the open circuit potential of gold and by the ellipsometric parameter variation during albumin immobilization. In both experiments the parameters reached stable values within 10-15 min. The albumin adsorption layer thickness measured with the ellipsometer was about 1.5 nm. The adsorption of albumin under applied potential was also investigated and it was found that both positive and negative applied potential promote albumin adsorption. Changes in the optical parameters of bare gold and albumin adsorbed onto gold surface under applied potential were investigated with in situ ellipsometry. The similarity and reversibility of the optical changes showed that adsorbed albumin was stable on the gold surface under the applied potential range (-200-600 mV). The cyclic voltammograms of K3Fe(CN)6 on the modified gold surface showed that albumin could partly block the oxidation and reduction reaction.

Adsorption↗

PubMed2004

Silicon surface modification with a mixed silanes layer to immobilize proteins for biosensor with imaging ellipsometry.

One kind of surface modification method on silicon wafer was presented in this paper. A mixed silanes layer was used to modify silicon surface and rendered the surface medium hydrophobic. The mixed silanes layer contained two kinds of compounds, aminopropyltriethoxysilane (APTES) and methyltriethoxysilane (MTES). A few of APTES molecules in the layer was used to immobilize covalently human immunoglobulin G (IgG) on the silicon surface. The human IgG molecules immobilized covalently on the modified surface could retain their structures well and bind more antibody molecules than that on silicon surface modified with only APTES. This kind of surface modification method effectively improved the sensitivity of the biosensor with imaging ellipsometry.

Biosensing Techniques↗

PubMed2004

Covalent immobilization of proteins for the biosensor based on imaging ellipsometry.

In the development of biosensors, the immobilization of biomolecules at interfaces played a crucial role. The feasibility of using 3-aminopropyltriethoxysilane (APTES) and glutaraldehyde (Glu) to modify silicon surface to immobilize covalently protein for immunoassay with the biosensor based on imaging ellipsometry was investigated. The higher density and stability of human IgG layer could be obtained on the silicon surface modified with APTES and Glu than that on the silicon surface modified with dichlorodimethylsilane (DDS). The human IgG molecules immobilized covalently on APTES-Glu surface bound more anti-IgG molecules than that on DDS surface, which indicated that the human IgG molecules could maintain higher binding capability on APTES-Glu surface. Tween 20 was able to block the undesirable adsorption on APTES-Glu surface, and also enhanced the recognition between human IgG and its antibody on both APTES-Glu and DDS surfaces. The combination of this protein covalent immobilization and the biosensor has the potential to be developed into a fast, simple immunoassay technique.

Antibody Affinity↗

PubMed2004

Tumor-specific expression detected with the use of an expression vector driven by human telomerase reverse transcriptase gene promoter.

To construct the tumor-specific expression vector driven by human telomerase reserve transcriptase gene promoter, we amplified a fragment of the enhanced green fluorescent protein (EGFP) gene from the pEGFP-N1 plasmid and cloned it into the multiple cloning site of the pLNCX vector, then named the recombinant as pLNCX-EGFP. The fragment of human telomerase reverse transcriptase gene promoter (hTERT) was amplified from the human genome with the use of human telomerase reserve transcriptase gene-specific primers and cloned into the pLNCX-EGFP vector, from which the cytomegalovirus promoter had previously been removed through the use of restriction enzymes, in sense orientation relative to the green fluorescent protein coding sequence. Then the expression vector pLNT-EGFP--under the control of the human telomerase reserve transcriptase gene promoter, which contains green fluorescent protein reporter gene-was successfully constructed. To detect the transcriptional activity of the human telomerase reserve transcriptase gene promoter, we conducted transient transfection of this specific expression vector into human lung fibroblast (HLF) cell lines with high telomerase activity and normal human fetal lung fibroblast (WI38) cell lines without telomerase activity. The results of transient transfection showed that the pLNT-EGFP vector strongly expressed the green fluorescent protein reporter gene in telomerase-positive cells but not in telomerase-negative cells.

Base Sequence↗

PubMed2004

[Oriented immobilization of human IgG by protein A on imaging ellipsometry biosensor].

The biosensor based on optical imaging ellipsometry, can be used to detect directly, without labeling, the surface concentration of biomolecules on solid surface. The feasibility of using protein A to immobilize antibody on the silicon surface of the imaging ellipsometry biosensor was investigated in this study. The results showed that the anti-IgG immobilized by the protein A on silicon surface could bind effectively human IgG, and the human IgG immobilized on silicon surface by protein A bound more polyclonal antibody molecules than that immobilized on silicon surface directly, suggesting that protein A might block the surface to prevent the absorption of human IgG on surface directly, which might compromise its native configuration. The silicon surface modified with protein A is expected to be used to immobilize a variety of antibodies, as protein A can bind selectively the Fc regions of many mammalian IgG. The combination of imaging ellipsometry and the protein A surface modification has the potential to be developed into immunoassays of high sensitivity.

Biosensing Techniques↗

PubMed2003

Study of the adsorption of fibrinogen on gold-coated silicon wafer by an impedance method.

In 0.1 mol/l KH(2)PO(4)-Na(2)HPO(4) (pH 7.80) buffer solution, the potential of zero charge (PZC) and the open circuit potential of gold-coated silicon were determined to be about -0.6 and +0.10 V (vs SCE), respectively. The open circuit potential was higher than the PZC, which indicated that the surface of the gold-coated electrode had a positive charge. The ellipsometry experiment showed that the adsorption of fibrinogen onto the gold-coated silicon wafer surface arrived at a saturated state when the adsorption time exceeded 50 min. The percentage of surface without adsorbed protein, theta, was about 63%. This means that the proportion of surface actually occupied by fibrinogen was only about 37% after the adsorption arrived at saturation. The solution/protein capacitance value was determined in an impulse state around -0.59 V (vs SCE) and was stable (4.2x10(-5) F) at other potentials.

Adsorption↗

PubMed2003

A label-free multisensing immunosensor based on imaging ellipsometry.

An immunosensor based on imaging ellipsometry and its potential applications was demonstrated in this paper. It has been proven a fast, reliable, and convenient method to quantify the thickness distribution of protein layers or detect protein concentration in solution. Combined with a protein chip, the immunosensor was able to detect multiple analytes simultaneously without any labeling. Preliminary results demonstrated how this immunosensor could be used to monitor several independent biospecific binding processes in real-time and in situ conditions.

Animals↗

PubMed2003

Feasibility of protein A for the oriented immobilization of immunoglobulin on silicon surface for a biosensor with imaging ellipsometry.

The feasibility of using protein A to immobilize antibody on silicon surface for a biosensor with imaging ellipsometry was presented in this study. The amount of human IgG bound with anti-IgG immobilized by the protein A on silicon surface was much more than that bound with anti-IgG immobilized by physical adsorption. The result indicated that the protein A could be used to immobilize antibody molecules in a highly oriented manner and maintain antibody molecular functional configuration on the silicon surface. High reproducibility of the amount of antibody immobilization and homogenous antibody adsorption layer on surfaces could be obtained by this immobilization method. Imaging ellipsometry has been proven to be a fast and reliable detection method and sensitive enough to detect small changes in a molecular monolayer level. The combination of imaging ellipsometry and surface modification with protein A has the potential to be further developed into an efficient immunoassay protein chip.

Animals↗

PubMed2003

Signal transduction in matrix contraction and the migration of vascular smooth muscle cells in three-dimensional matrix.

The interaction of vascular smooth muscle cells (SMCs) and extracellular matrix plays important roles in vascular remodeling. We investigated the signaling pathways involved in SMC-induced matrix contraction and SMC migration in three-dimensional (3D) collagen matrix. Matrix contraction is inhibited by the disruption of actin filaments but not microtubules. Therefore, we investigated the roles of signaling pathways related to actin filaments in matrix contraction. SMC-induced matrix contraction was markedly blocked (-80%) by inhibiting the Rho-p160ROCK pathway and myosin light chain kinase, and was decreased to a lesser extent (30-40%) by a negative mutant of Rac and inhibitors of phosphatidylinositol 3-kinase (PI 3-kinase) or p38 mitogen-activated protein kinase (MAPK), but it was not affected by the inhibition of Ras and Cdc42-Wiskott-Aldrich syndrome protein (WASP) pathways. Inhibition of extracellular-signal-regulated kinase (ERK) decreased SMC-induced matrix contraction by only 15%. The migration speed and persistence of SMCs in the 3D matrix were decreased by the inhibition of p160ROCK, PI 3-kinase, p38 MAPK or WASP to different extents, and p160ROCK inhibitor had the strongest inhibitory effect. Our results suggest that the SMC-induced matrix contraction and the migration of SMCs in 3D matrix share some signaling pathways leading to force generation at cell-matrix adhesions and that various signaling pathways have different relative importance in the regulations of these processes in SMCs.

Actin Cytoskeleton↗

PubMed2003

Characterization of the tissue-specific expression of the s100P gene which encodes an EF-hand Ca2+-binding protein.

S100 proteins are a calcium-binding protein family containing two EF-hand domains exclusively expressed in vertebrates and play roles in many cellular activities. Human S100P gene was first cloned as a 439 bp cDNA in placenta and it was found to be associated with human prostate cancer. Here we describe the cloning of the 1297 bp full-length cDNA, and the characterization of the tissue-specific expression of the human S100P gene. It is abundantly expressed in many tissues including placenta by Northern blot and RT-PCR analysis, unlike the expression pattern of other S100 family genes.

Amino Acid Sequence↗

PubMed2003

[Clinical significance of regional lymphadenectomy in radical resection of ductal adenocarcinoma in the pancreatic head].

OBJECTIVE: To prospectively evaluate the long-term effect of pancreaticoduodenectomy with regional lymphadenectomy. METHODS: One hundred and twenty-one patients with ductal adenocarcinoma in the pancreatic head treated from 1996 to 2001 were studied prospectively. The enrollment of the patients was dependent on 7 criteria. The patients were divided into two groups: regional lymphadenectomy (group A, n = 50) and routine Whipple procedure (group B, n = 71). Their pre- and postoperative conditions, clinicopathological data, survival rates were studied. RESULTS: It was comparable between the 2 groups in age, sex, preoperative risk factors, operative management, and postoperative complication. Clinicopathological results showed no difference in tumor size and plexus invasion; but the frequency of lymph node involvement and the amount of resected lymph node in group A were significantly higher than those in group B. The rate of local recurrence was significantly higher in group A than in group B. The survival rates of 1-, 3-, 5-year in group A were 70.8%, 31.4%, 20.9%, respectively, which were higher than those in group B. No direct relations were observed between nodal involvement and survival rate. CONCLUSION: Lymphadenectomy in radical pancreaticoduodenectomy could remove lymph nodes effectively and sufficiently, and reduce the rate of local recurrence so as to improve the long-term survival rate.

Adult↗

PubMed2003

The mitogenic and anti-apoptotic activity of tumor conditioned medium on endothelium.

This study was designed to observe the effect of tumor conditioned medium (TCM) on the proliferation and apoptosis of human umbilical vein endothelial cells (HUVECs). HUVECs were exposed to TCM from breast carcinoma cell line MDA-MB-231, then we measured their proliferation, apoptosis and cell cycle distribution by MTT and flow cytometery (FCM). Following the stimulation of TCM, HUVECs showed higher pro-mitogenic and anti-apoptotic ability than did the negative control group (ECGF-free medium with 20% FBS), but a similar ability to the positive control group (medium with ECGF and 20% FBS). From these results, we can conclude that breast carcinoma cell line MDA-MB-231 could secret soluble pro-angiogenic factors that induce HUVEC angiogenic switching, including cell cycle progression, proliferation and growth. The role and character of these factors remain to be further studied.

Angiogenesis Inducing Agents↗

PubMed2003

A proteomic study on cell cycle progression of endothelium exposed to tumor conditioned medium and the possible role of cyclin D1/E.

This study was designed to comprehensively analyze the differential expression of proteins from human umbilical vein endothelial cells (HUVECs) exposed to tumor conditioned medium (TCM) and to identify the key regulator in the cell cycle progression. The HUVECs were exposed to TCM from breast carcinoma cell line MDA-MB-231, then their cell cycle distribution was measured by flow cytometer (FCM). The role of protein in cell cycle progression was detected via two-dimensional polyacrylamide gel electrophoresis (2-DE) and western blotting. Following the stimulation of TCM, HUVECs showed a more cells in the S phase than did the negative control group (ECGF-free medium with 20% FBS), but the HUVECs' level was similar to the positive control group (medium with 25 micrograms/ml ECGF and 20% FBS). Increased expression of cyclin D1/E and some changes in other related proteins occurred after incubation with TCM. From our results, we can conclude that breast carcinoma cell line MDA-MB-231 may secrete soluble pro-angiogenic factors that induce the HUVEC angiogenic switch, during which the expression of cell cycle regulator cyclin D1/E increases and related proteins play an important role in this process.

Angiogenesis Inducing Agents↗

PubMed2002

[Visualization of the interaction between IL-6 and IL-6R by imaging ellipsometry].

Imaging Ellipsometry is one of recently developed optical surface-sensitive methods for the investigation of various aspects of biomolecules adsorption on solid surfaces and biomolecules interactions. It has advantages of high sensitivity to layer-thickness, big area of view, high sampling speed, and high lateral resolution. Compared with other solid phase methods such as enzyme linked immunosorbent assay, immunofluorescence and radioimmunoassay, imaging ellipsometry has the advantage of not involving any labelling of reactants and it is a relatively inexpensive method and easy to handle. In this report, the mono-layers of IL-6 and IL-6 receptor were visualized as well as their interaction.

Diagnostic Imaging↗

PubMed2002

[cDNA microarray in the gene expression pattern in lymphatic metastasis of pancreatic carcinoma].

OBJECTIVE: Analysis of differential gene expression profiles by cDNA microarray in pancreatic carcinoma with or without lymphatic metastasis. METHODS: cDNA microarray was prepared by spotting polymerase chain reaction (PCR) products of 4 000 human genes onto specially treated glass slides. The cDNA probes were prepared by labeling normal tissue mRNA and cancer tissue mRNA with Cy3-dUTP and Cy5-dUTP, separately through reverse transcription. The mixed probes were, then, hybridized to the cDNA microarray. The chips were scanned by ScanArray 3000 laser scanner (General Scanning, Inc) on two wavelengths. The acquired image was analyzed by ImaGene 3.0 software (BioDiscovery, Inc). The intensity of each spot on the two wavelengths represented the quantity of Cy3-dUTP and Cy5-dUTP, with Cy5 to Cy3 ratio computed on each. RESULTS: Fifty-six genes (including 24 previously reported) exhibited differential expressions in 2 specimens of pancreatic carcinoma with lymphatic metastasis and 2 without. CONCLUSION: cDNA microarray provides an promising approach to specific gene expressions of the presence of lymphatic metastasis in human pancreatic carcinoma.

Aged↗

PubMed2002

[MC3T3-E1 osteoblasts adhesion to micropatterned surfaces].

Cell adhesion to material surface plays an important role in regulating cell function such as proliferation and differentiation. Surface patterning provides a useful method to control cell spatial distribution and adhesion to substance. Here microcontact printing and microfluidic channels were introduced to pattern MC3T3 E1 osteoblasts on silicon substance. Dichlordimethylsilane (DMS) was used in microcontact printing to generate the alternating domains of DMS and non-DMS, and cells preferentially adhered to the non-DMS and hydrophilic region. On the patterned surfaces generated from collagen and albumin solutions with microfluidic channels, cells preferentially localized in the collagen-coated region. The results also showed that micropatterning could be a useful method to study the effect of surface chemistry on cell adhesion and other functions.

Cell Adhesion↗