Biomedical subjects

Xing Chen

Publications and source records attributed to Xing Chen.

48 records · Page 3Linked to original sources

PubMed2003

[Comparison of composite grafting of autoskin with acellular dermal matrix from different sources].

OBJECTIVE: To compare the composite grafts of acellular dermal matrix (ADM) from different sources with autoskin. METHODS: Six local white mini pigs were employed for the experiment. The pigs were randomly divided into four groups according to different skin grafts, i.e. A (human ADM with razor thin autoskin), B (porcine ADM with razor thin autoskin), C (razor thin autoskin only), and D (split thickness autoskin) as control. The survival rate, the contraction degree of the grafts, and the histological changes in grafting area were observed at 2, 4, 8, 12 and 24 hours after the operation. RESULTS: The grafted area in both A and B groups appeared smooth and elastic with satisfactory graft survival. The in growth of the host reparative cells such as fibroblast and vascular endothelium could be induced by composite grafts of different ADMs with skin grafting. The contraction areas in A and B groups seemed bigger than those in C and D groups. The tissue structure of grafting areas was similar to that of split thickness skin grafting area at 24 post-operation weeks. CONCLUSION: Combination of the homogenous and heterogeneous ADMs with autografts exhibited similar biological function during the observation period (24 weeks after operation). Xenogenous ADMs might have broader clinical applications.

Animals↗

PubMed2003

[Construction of GPI-CTLA4Ig chimeric molecule and its expression on CHO-dhfr(-) cells].

AIM: To develop a novel immunosuppressant GPI-CTLAIg modified by glycosyl-phosphatidylinositol(GPI). METHODS: GPI-modified CTLAIg was produced by linking-up of CTLA4Ig with GPI-modification signal sequences from decay-accelerating factor (DAF). Chimeric molecule GPI-CTLA4Ig gene was cloned into eukaryotic expression vector pCI-dhfr. Using lipofectine-mediated gene transfer technique, pCI-GPI-CTLA4Ig was transfected into CHO-dhfr(-) cells, and the transfectants were screened by methotrexate (MTX). Expression of the recombinant protein was assessed by RT-PCR, ELISA, cell immunofluorescence staining and Western blot, and the purification of expressed protein was performed by protein A affinity chromatography. RESULTS: The chimeric molecule GPI-CTLA4Ig has been constructed and stablely expressed on CHO-dhfr(-) cells. CONCLUSION: GPI-modified CTLAIg will may be used as novel immunosuppressant for suppressing reaction in graft rejection.

Animals↗

PubMed2003

[Preparation of rabbit anti-Syk antibody and its application in breast cancer diagnosis].

AIM: To prepare rabbit anti-Syk antibody and analysis its application in breast cancer diagnosis. METHODS: The rabbits were immunized with recombinant mouse Syk protein to prepare antibody against Syk. The purity and specificity of the antibody were analyzed by Western blot. The expression of Syk protein was detected by immunohistochemical staining. RESULTS: The titer of serum anti-Syk antibody was 1:6 400 (A450 = 1. 03) 6 weeks after the immunization. The SDS-PAGE and Western blot analysis showed that there was a obvious protein band with Mr 72,000, confirming the specificity of obtained anti-Syk antibody. It was displayed by immunohistochemical staining with anti-Sykantibody that in normal breast tissue Syk was high expression; while in infilfrative dustal carcinoma of breast tissue the expression of syk was negative. CONCLUSION: The rabbit anti-Syk antibody with high titer and specificity has been prepared. The Syk is high expression in normal breast tissue, but is deficient in breast cancer tissue. The result may be useful for clinical diagnosis of breast cancer.

Animals↗

PubMed2002

Large-scale synthesis of sodium and potassium titanate nanobelts.

A low-temperature solution-based synthetic method was developed for the large-scale synthesis of one-dimensional nanostructures of alkali titanates. Two kinds of highly pure ribbonlike titanates were synthesized successfully in gram quantities without introducing any templates or catalysts. The structure and composition of the titanates were characterized by XRD, HRTEM, and EDX. The chemical and physical properties were preliminarily characterized, and some distinctive properties were observed.

Journal Article↗

PubMed2002

Self-assembling vanadium oxide nanotubes by organic molecular templates.

Vanadium oxide nanotubes were synthesized as the main product by hydrothermal self-assembling from ammonium metavanadate (NH(4)VO(3)) and organic molecules as structure-directing templates. Several kinds of templates including primary amines (C(n)H(2n+1)NH(2)), alpha,omega-diamines (H(2)N[CH(2)](n)NH(2)), and quaternary ammonium salt (CTAB) were demonstrated to be appropriate for the formation of nanotubes. The morphologies and structures of the nanotubes were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and thermal gravimetric analysis (TGA). The nanotubes were found forming together with the layered structures and the sheetlike structures. On the basis of the growth mechanism of WS(2) nanotubes proposed by our group, a possible rolling mechanism was proposed, which might be a suitable general formation mechanism for types of nanotubes from lamellar structures.

Journal Article↗

PubMed2002

[Transpedicular instrumentation and interbody fusion for spinal tuberculosis].

OBJECTIVE: To evaluate the surgical outcomes of spinal tuberculosis treated with transpedicular instrumentation and interbody auto-grafting. METHODS: Thirty-four patients of thoracolumbar tuberculosis were treated with transpedicular instrumentation, radical focus resection and interbody auto-grafting, combined with 6- or 9-month antituberculous medication from October 1996 to November 1998. All patients were followed-up prospectively for 3 to 5 years postoperatively. RESULTS: The back pain and tuberculous symptoms were relieved about one week postoperatively. The erythrocyte sedimentation rate came back to normal level from 4 to 6 weeks postoperatively. The solid interbody arthodesis was achieved from 4 to 6 months postoperatively. All patients were cured of tuberculous lesions in spinal column or in other region, and there were no tuberculous recurrence. In 12 patients, average preoperative kyphosis angle was 24 degrees (range 10 degrees approximately 32 degrees ), and that was 9 degrees (range 5 degrees approximately 13 degrees ) immediately after surgery. The average correction of kyphotic deformity was 15 degrees and was maintained unchanged in follow-up period postoperatively. Nine patients who had type-C or type-D neurological lesions, according to Frankel gradation, had complete recovery one year postoperatively. CONCLUSION: In spinal tuberculous operation, transpedicular instrumentation and interbody fusion are essential in providing rigid stabilization of spinal column, correcting or preventing kyphotic deformity, accelerating focus healing up and shortening chemotherapy period. Transpedicular instrumentation is necessary in short segments fixation and preserving functional unit of spine.

Adult↗

PubMed2002

Development of a recombinant HSP110-HER-2/neu vaccine using the chaperoning properties of HSP110.

Several studies have shown that when purified from a tumor, certain heat shock proteins (HSPs) can function as effective vaccines against the same tumor by virtue of their ability to bind tumor-specific peptides. However, only a small fraction of the associated peptides would be expected to be immunogenic, in addition to which, the clinical application of this vaccine requires the availability of a surgical specimen of sufficient quantity for purification of the HSP. The present study describes a new approach for the development of natural HSP vaccines that do not have these limitations. This approach uses a recombinant HSP that is noncovalently bound to a recombinant tumor protein antigen by heat shock. HSP110 has been selected for this purpose, because it has been shown to be a highly efficient molecular chaperone in binding to large protein substrates. We show that a "natural chaperone complex" between HSP110 and the intracellular domain (ICD) of human epidermal growth factor receptor 2 protein (HER-2)/neu is formed by heat shock. This HSP110-ICD vaccine elicited both CD8(+) and CD4(+) T-cell responses against ICD as determined by an antigen-specific IFN-gamma production in an enzyme-linked immunospot assay (ELISPOT). In vivo depletion studies revealed that the CD8(+) T-cell response was independent of CD4(+) T-cell help. The HSP110-ICD complex also significantly enhanced ICD-specific antibody responses relative to that seen with ICD alone. No CD8(+) T cell or antibody response was detected against HSP110. The use of recombinant HSP110 to form natural chaperone complexes with large protein antigens represents a new and powerful approach for the design of protein-targeted cancer vaccines.

Animals↗

PubMed2002

Insulin inhibits dexamethasone effect on angiotensinogen gene expression and induction of hypertrophy in rat kidney proximal tubular cells in high glucose.

The present studies investigated whether insulin inhibits the stimulatory effect of dexamethasone (DEX) on angiotensinogen (ANG) gene expression and induction of hypertrophy in rat immortalized renal proximal tubular cells (IRPTCs) in a high-glucose milieu. Rat IRPTCs were cultured in monolayer. ANG and ANG mRNA expression in IRPTCs were quantified by a specific RIA for rat ANG and by RT-PCR assay, respectively. A fusion gene containing the full length of the 5'-flanking region of the rat ANG gene linked to a chloramphenicol acetyl transferase reporter gene was introduced into IRPTCs. The level of fusion gene expression was determined by cellular chloramphenicol acetyl transferase enzymatic activity. Cellular hypertrophy was assessed by flow cytometry, cellular p27(Kip1) protein expression, and protein assay. Our results showed that high glucose (i.e. 25 mM) and DEX (10(-7) M) additively stimulated ANG gene expression and induced IRPTC hypertrophy. Insulin inhibited the effect of high glucose and DEX on these parameters. The inhibitory effect of insulin was reversed by PD 98059 (a MAPK inhibitor) but not by wortmannin (a phosphatidylinositol-3-kinase inhibitor). These results demonstrate that insulin is effective in blocking the stimulatory action of high glucose and DEX on ANG gene expression and induction of IRPTC hypertrophy, suggesting its important role in preventing local intrarenal renin-angiotensin system activation and renal proximal tubular cell hypertrophy induced by hyperglycemia and glucocorticoids in vivo.

Angiotensinogen↗

PubMed2002

Essential role(s) of the intrarenal renin-angiotensin system in transforming growth factor-beta1 gene expression and induction of hypertrophy of rat kidney proximal tubular cells in high glucose.

These studies investigated the question of whether the intrarenal renin-angiotensin system (RAS) is essential for transforming growth factor-beta1 (TGF-beta1) gene expression and induction of hypertrophy of renal proximal tubular cells in high glucose in vitro. Antisense and sense angiotensinogen (ANG) cDNAs were stably transfected into rat immortalized renal proximal tubular cells (IRPTC). ANG secretion from rat IRPTC was quantified by a specific RIA for rat ANG. Cellular ANG, TGF-beta1, and collagen alpha1 (type IV) mRNA levels were determined by Northern blot analysis or by reverse transcriptase-PCR assay. Hypertrophy of IRPTC was analyzed by Western blotting of cellular p27(Kip1) protein, flow cytometry, and cellular protein assay. The results showed that stable transfer of antisense ANG cDNA into IRPTC suppressed the basal TGF-beta1 and collagen alpha1 (type IV) mRNA expression and blocked the stimulatory effect of high glucose (i.e., 25 mM) on TGF-beta1 and collagen alpha1 (type IV) mRNA expression and induction of IRPTC hypertrophy. In contrast, stable transfer of sense ANG cDNA into IRPTC had no significant effect on these parameters. These data demonstrate that local intrarenal RAS activation is essential for TGF-beta1 gene expression and induction of hypertrophy of renal proximal tubular cells in high glucose.

Angiotensinogen↗

PubMed2002

Insertion of PCB to treat traumatic cervical intervertebral disc herniation.

OBJECTIVE: To evaluate the clinical effect of PCB (a new anterior cervical instrumental system combining an intradiscal cage with an integrated plate) in treating traumatic cervical intervertebral disc herniation. METHODS: Anterior decompression and PCB internal fixation were used in 22 patients with traumatic cervical intervertebral disc herniation. They were followed up from 3 to 16 months and analyzed by symptom and image data. Among them, 16 patients underwent fixation at one level and 6 patients at two levels. RESULTS: This technique did not cause intraoperative complications. After surgery no screw backout or device failure was found. Based on the JOA grade, 20 patients improved clinically and 2 gently because of serious cervical stenosis. The general excellent rate was 90.9%. CONCLUSIONS: PCB internal fixation is stable. Morbidity of donor and acceptor sites is less. No collars are needed after surgery.

Adult↗

PubMed2002

[Inhibition on the endocytosis of early visceral yolk sac induced by homocysteine in rats].

The effect of homocysteine (HCY) on the development and endocytosis of rat visceral yolk sac (VYS) was investigated. A preliminary method on early (GD9.5) rat yolk-sac placenta cultured in vitro was established by techniques using microdissection and transplantation. The results showed that HCY did damage VYS development and blood vessel formation, the damages were characterized by shrunk surface, small or defective blood island and significant reduction of diameter (P < 0.01). HCY also inhibited the process of VYS transport, specifically the endocytosis (as measured by [U-14C] sucrose uptake), the rate of endocytosis was significantly decreased when HCY was included in the medium (P < 0.01). These results suggested that the inhibition of sanguimotor development and the reduction of endocytosis induced by HCY may directly correlate with the teratologic and embryopathologic events.

Animals↗

PubMed1999

A Novel One-Step Diastereo- and Enantioselective Formation of trans-Azetidinones and Its Application to the Total Synthesis of Cholesterol Absorption Inhibitors.

An efficient and practical asymmetric process was developed for the synthesis of azetidinone-based cholesterol absorption inhibitors. Key to this synthesis was the discovery of a novel one-step diastereo- and enantioselective formation of trans beta-lactams starting from commercially available 3(S)-hydroxy-gamma-lactone. Various trans beta-lactams can be prepared in good yields and with better than 95:5 enantio- and diastereoselctivity. A Lewis acid-catalyzed aldol condensation and a highly enantioselective oxazaborolidine-catalyzed chiral reduction completes the side chain.

Journal Article↗