Biomedical subjects

Gang Chen

Publications and source records attributed to Gang Chen.

At least 91 records · Page 5Linked to original sources

PubMed2006

[Clavicular hook plate in the treatment of dislocation of acromioclavicular joint and fracture of distal clavicle].

OBJECTIVE: To evaluate the curative effects of AO clavicular hook plate in the treatment of dislocation of acromioclavicular joint and fracture of distal clavicle. METHODS: We retrospectively analyzed the clinical data of 39 patients with acromioclavicular joint dislocation or distal clavicle fractures treated with clavicular hook plate: 16 suffered from dislocation of acromioclaviculr joint, 18 suffered from far end collarbone fractures, and 5 patients had both symptoms. RESULTS: The 39 patients were followed up for 12 months averagely. All patients got good reduction and fixation. The acromioclavicular joint subluxation, breakage, and loosening of the clavicular hook plate were not observed. The acromioclavicular joint recovered quickly. CONCLUSION: AO clavicular hook plate is a good choice for acromioclavicular joint dislocation and distal clavicular fracture.

Acromioclavicular Joint↗

PubMed2006

[Detection of micrometastasis in mediastinal lymph nodes in operable non-small cell lung cancers].

OBJECTIVE: Using the LUNX-mRNA as a marker and RT-PCR technique to assess mediastinal lymph nodes in patients with operable NSCLC, to evaluate at gene level the feasibility of this method in detection of micrometastasis in NSCLC and the necessity of systematic mediastinal lymphadenectomy during surgery. METHODS: Twenty patients with operable NSCLC were involved in this study. The mediastinal lymph nodes were taken during operation. RT-PCR assay was carried out to detect the LUNX-mRNA. Ten cases with benign lung disease were assayed by the same method as control. RESULTS: Seventy one mediastinal lymph nodes were obtained from 20 patients, 8 (11.3%) of which showed histologically metastasis with HE staining, while 23 (32.4%) were LUNX-mRNA positive by RT-PCR, P < 0.001. Micrometastasis was detected in 25.4% of all lymph nodes. LUNX-mRNA was found to be positive in 23.6% of lymph nodes from 15 patients with stage I A-II B NSCLC compared with 62.5% from 5 patients with stage III NSCLC, with a significant difference (P = 0.003). CONCLUSION: About 25.4% of mediastinal lymph nodes are with micrometastasis in patients with operable NSCLC. Systematic mediastinal lymphadenectomy is necessary to deal with the regional lymph nodes during surgery.

Adult↗

PubMed2006

[The neuromuscular compartments of the flexor carpi ulnaris and the flexor carpi radialis].

OBJECTIVE: Report on the intramuscular innervation and vascular supply of the flexor carpi ulnaris (FCU) and the flexor carpi radialis (FCR), the musculo tendon architecture, i.e., the physiological cross-sectional area and fiber length; and explore the possibility of splitting FCU and FCR into 2 parts with individual independent function. METHODS: Anatomic study, angiogram and Sibler's staining technique were carried on human and monkey cadavers. The electric stimulation study was used to reveal independent contraction of each part on monkey FCU and FCR. RESULTS: It was found that the innervation and blood supply of FCU and FCR come primarily from the proximal neurovascular pedicles. The primary nerve and vascular branch supplying the muscles were divided into 2 subbranches and inserted the proximal quarter of the muscle belly. Then each of the nerve and blood subbranches mn parallel to the central tendon on each side supplying the radial and ulnar compartments of FCU and FCR toward the distal musculotendinous junction. Independence of function of each compartment was confirmed in electrical stimulation studies in primate FCU and FCR. The results of each compartment of the human FCU and FCR architectures were measured and compared with the extensor pollicis longus and the extensor digitorum communis to the index, middle, ring, and small. CONCLUSIONS: Both FCU and FCR can be split from the distal to the proximal along its tendon into 2 independently functioning neuromuscular compartments. Both radial compartment and ulnar compartment have its own nerve and adequate blood supply. And the study provides useful information for enabling the local transfer of the two muscles as a whole or two separate compartments, both for resurfacing skin soft-tissue defects and for functional tendon transfer.

Adult↗

PubMed2006

[Preventing recurrent laryngeal nerve lesions by anastomosing it during thyroid surgery].

OBJECTIVE: To study how to prevent recurrent laryngeal nerve (RLN) lesions by anastomosing it during thyroid surgery. METHOD: In the present study 517 patients with thyroid diseases underwent thyroid surgery from January 1993 to May 2005, with RLNs of 163 cases (187 sides, A group) anatomized and RLNs of 354 cases (438 sides. B group) not anatomized. The RLN in B group were protected generally during thyroid surgery. RLNs of A group were anatomized partly or totally. RESULT: (1) In A group RLNs of 123 cases were partly anatomized and 64 totally. None of all RLNs was injuried. (2) B group 3 sides of 3 cases of all RLNs was injuried. The rate of RLN's lesion is 0.7%, which is significantly higher in A group than in B group. CONCLUSION: Anastomosing RLN during thyroid surgery may prevent its lesions. The length of anatomized RLN must vary with the area and position of thyroid pathological changes. The RLN needn't be anatomized in these patients with the benign thyroid pathological changes which is far away trachea-oesophagus channel.

Adult↗

PubMed2006

[Preparation of a concanavalin A immobilized affinity column and its application in the structural analysis of ribonuclease B].

The research on glycoproteomes represents an interesting field in the functional proteomics research. Affinity chromatography and mass spectrometry are powerful techniques that are used for gaining valuable information on glycoproteomes because glycoproteins and their unusual forms resulting from protein glycosylation can be important indicators of several diseases. In this study, the concanavalin A (Con A) immobilized silica packing was prepared and used for the separation of glycoprotein and glycopeptides. A very low, non-specific adsorption on the Con A affinity column was demonstrated by mass recovery of bovine serum albumin at more than 98.5%. The effect of concentration of methyl-alpha-D-mannopyranoside (alpha-Me-D-Man) in the mobile phase and the effect of flow rate on the retention behavior of ribonuclease B (RNase B) were also investigated. The standard glycoprotein RNase B was separated under optimized conditions using 0.2 mol/L alpha-Me-D-Man in the mobile phase at a flow rate of 0.5 mL/min. Meanwhile, the oligosaccharides and glycopeptides were enriched using a Con A column after digestion of the purified RNase B with peptide-N-glycosidase F (PNGase F) and trypsin. The structure of N-linked glycan and the rate and the site of glycosylation of RNase B were determined by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). Glycoproteins and glycopeptides in human serum and digest solution could be separated by this method. The results showed that this method is rapid and sensitive for the purification and characterization of glycoproteins and glycopeptides.

Animals↗

PubMed2006

[Effects of tetramethylpyrazine on expression of vascular endothelial growth factor and hypoxia-induced factor-1alpha by rat peritoneal macrophages].

OBJECTIVE: To investigate the effects of tetramethylpyrazine on lipopolysaccharides (LPS)-induced expression of vascular endothelial growth factor (VEGF) and hypoxia-induced factor-1alpha (HIF-1alpha) in macrophages. METHOD: Rat peritoneal macrophages were treated with LPS, and at the same time given different doses of tetramethylpyrazine. The secreation of VEGF was determined by ELISA test, and MTT assay was used to examine cells proliferation. Western blot assay was used to examine the expression of HIF-1alpha. RESULT: 100 microg x mL(-1) and 10 microg x mL(-1) tetramethylpyrazine decreased the secretion of VEGF and also inhibited the expression of HIF-1alpha by LPS-induced macrophages. But these doses of tetramethylpyrazine had no effect on the cells proliferation. CONCLUSION: Tetramethylpyrazine could inhibit the secretion of VEGF by LPS-induced macrophages, and the mechanism must be associated with inhibiting the expression of HIF-1alpha. The inhibition effect was not due to inhibition of the proliferation of macrophages.

Animals↗

PubMed2006

[The project and simulation of a compositive miniature spectrum instrument based on the array of Fabry-Perot cavity].

This paper advances a kind of micro-spectrometer based on Fabry-Perot cavity's character of filtering the waves. The basic structure of the micro-spectrometer is the array of Fabry-Perot cavity which contains many different lengths of cavity on the substrate of silicon, consequently the authors can achieve the detection at several wavelengths simultaneously. The unit of probing is a Fabry-Perot cavity made up of the substrate of silicon-metal film-silicon dioxide layer-metal film. The authors carried out the corresponding simulation. In the basic structure of aluminum film(14 nm)-silicon dioxide layer-silver film(39 nm), the resolution can reach 15 nm. When the area of a unit of probing is 0.14 mm x 0.14 mm only, it can reach the luminous flux of miniature grating spectrum instrument (the minimum volume in the order of cm), but the volume of the part of spectrum detection is only of the order of mm. The design size of the micro-spectrometer is a few millimeters. Furthermore it has no movable parts and could detect several wavelengths at the same time. It is possible to fabricate such micro-spectrometer through existing processing methods of IC technology.

English Abstract↗

PubMed2006

[Histopathological changes post cryoablation in canine myocardium].

OBJECTIVE: The purpose of this study was to observe histopathological changes post cryoablation in canine myocardium, to characterize the specific ablation lesion post cryoablation. METHODS: Cryothermal ablation was applied on myocardium (both epicardium and endocardium) of 14 mongrel dogs with different ablation parameters (-25 degrees C x 4 min, -50 degrees C x 4 min, -75 degrees C x 4 min, -75 degrees C x 2 min, -75 degrees C x 6 min, -75 degrees C x 8 min). Lesion dimensions and histopathologic changes were observed. RESULTS: The discrete, sharply delimited lesions were detected in cryoablated myocardium. Histologically, cryoablation in all temperatures studied induced heterogeneous necrosis of the myocardium. Lesion dimensions are related to freezing time and temperature. CONCLUSION: Cryoablation is a feasible and preferably choice for clinical application due to its controllable myocardium lesions.

Animals↗

PubMed2005

Electrophoresis microchips with sharp inlet tips, for contactless conductivity detection, fabricated by in-situ surface polymerization.

A novel method based on in-situ surface polymerization of methyl methacrylate (MMA) has been developed for rapid fabrication of poly(methyl methacrylate) (PMMA) electrophoresis microchips with sharp inlet tips. Prepolymerized MMA containing an ultraviolet (UV) initiator was directly sandwiched between a nickel template and a PMMA plate. The image of the relief on the nickel template was precisely replicated in the synthesized PMMA layer on the surface of the commercially available PMMA plate during UV-initiated polymerization at room temperature. The chips were subsequently assembled by thermal bonding of channel plates and cover sheets. The sample was directly introduced into the separation channel through a sharp inlet tip, which was placed in the sample vial, without use of an injection cross. The attractive performance of the novel PMMA microchips has been demonstrated by using contactless conductivity detection for determination of several inorganic ions. Such rapid and simple sample introduction leads to highly reproducible signals with relative standard deviations of less than 5% for peak responses. These new approaches significantly simplify the process of fabricating PMMA devices and show great promise for high-speed microchip analysis.

Journal Article↗

PubMed2005

Determination of glycosides and sugars in Moutan Cortex by capillary electrophoresis with electrochemical detection.

A method based on capillary electrophoresis with electrochemical detection has been developed for the separation and determination of paeoniflorin, sucrose, paeonoside, glucose, and fructose in Moutan Cortex for the first time. Effects of several important factors such as the concentration of NaOH, separation voltage, injection time, and detection potential were investigated to acquire the optimum conditions. The detection electrode was a 300 microm diameter copper disc electrode at a working potential of +0.60 V (versus saturated calomel electrode (SCE)). The five analytes can be well-separated within 12 min in a 40 cm length fused silica capillary at a separation voltage of 12 kV in a 75 mM NaOH aqueous solution. The relation between peak current and analyte concentration was linear over about 3 orders of magnitude with detection limits (S/N = 3) ranging from 0.9 to 1.3 microM for all analytes. The proposed method has been successfully applied to monitor glycoside and sugar contents in the real plant samples with satisfactory assay results.

Buffers↗

PubMed2005

Non-steroidal anti-inflammatory drug (NSAID) use and levels of a lipid oxidation marker in plasma and nipple aspirate fluids.

Non-steroidal anti-inflammatory drugs (NSAIDs) are thought to reduce cancer risk by inhibiting cyclo-oxygenases, resulting in deceased formation of inflammatory mediators and oxidative stress. We examined whether the level of one oxidative stress marker, 15-F(2t)-isoprostane, was affected by NSAID use in plasma and breast nipple aspirate fluids (NAF) of pre-menopausal women who were participating in a dietary intervention trial (n=121). Baseline levels of 15-F(2t)-isoprostane were lower in NSAID users than non-users in both NAF and plasma, although the differences did not persist after intervention. Over the duration of the study, information on NSAID use was collected five times, and average 15-F(2t)-isoprostane levels in both NAF and plasma exhibited a statistically significant trend for decreases with increased frequency of NSAID use. These results indicate that NSAID use can result in lower levels of 15-F(2t)-isoprostane, which may have implications for the effects of NSAID use on breast cancer risk.

Adult↗

PubMed2005

Novel oncolytic adenovirus selectively targets tumor-associated polo-like kinase 1 and tumor cell viability.

PURPOSE: Polo-like kinase 1 (plk1) is a serine/threonine protein kinase essential for multiple mitotic processes. Previous observations have validated plk1 as a promising therapeutic target. Despite being conceptually attractive, the potency and specificity of current plk1-based therapies remain limited. We sought to develop a novel plk1-targeting strategy by constructing an oncolytic adenovirus to selectively silence plk1 in tumor cells. EXPERIMENTAL DESIGN: Two artificial features were engineered into one wild-type adenovirus type 5 (wt-Adv5) genome to generate a new oncolytic adenovirus (M1). First, M1 contains a 27-bp deletion in E1A region, which confers potent, oncolytic efficacy. Second, M1 is armed with a fragment of antisense plk1 cDNA that substitutes the E3 region encoding 6.7K and gp19K. In this design, tumor-selective replication of M1 would activate the native adenovirus E3 promoters to express the antisense plk1 cDNA preferentially in tumor cells and silence tumor-associated plk1 protein. RESULTS: By virtue of combining oncolysis with plk1 targeting, M1 exhibited potent antitumoral efficacy in vitro and in vivo. Systemic administration of M1 plus cisplatin induced complete tumor regression in 80% of orthotopic hepatic carcinoma model mice that were otherwise resistant to cisplatin and disseminated metastases. CONCLUSIONS: Coupling plk1 targeting with oncolysis had shown superior antitumor efficacy. Present findings would benefit the development of novel oncolytic adenoviruses generally applicable to a wide range of molecule-based therapeutics.

Adenoviridae↗

PubMed2005

Fabrication of poly(methyl methacrylate) capillary electrophoresis microchips by in situ surface polymerization.

A novel method based on in situ surface polymerization of methyl methacrylate (MMA) has been developed for the rapid fabrication of poly(methyl methacrylate) (PMMA) capillary electrophoresis (CE) microchips. MMA containing both thermal and ultraviolet (UV) initiators was allowed to prepolymerize in a water bath to form a fast curing molding solution that was subsequently sandwiched between a nickel template and a PMMA plate. The images of the raised microchannels on the nickel template were precisely replicated into the synthesized PMMA substrates during the UV-initiated polymerization of the molding solution within 30 min under ambient temperature. The attractive performances of the novel PMMA microchips have been demonstrated in connection with amperometric detection for the separation and detection of several model analytes. The new approach significantly simplifies the process for fabricating PMMA devices and could be applied to other materials that undergo light-initiated polymerization.

Electrophoresis, Capillary↗

PubMed2005

Acute rejection is associated with antibodies to non-Gal antigens in baboons using Gal-knockout pig kidneys.

We transplanted kidneys from alpha1,3-galactosyltransferase knockout (GalT-KO) pigs into six baboons using two different immunosuppressive regimens, but most of the baboons died from severe acute humoral xenograft rejection. Circulating induced antibodies to non-Gal antigens were markedly elevated at rejection, which mediated strong complement-dependent cytotoxicity against GalT-KO porcine target cells. These data suggest that antibodies to non-Gal antigens will present an additional barrier to transplantation of organs from GalT-KO pigs to humans.

Animals↗

PubMed2005

The influence of baseline expression of human decay accelerating factor transgene on graft survival and acute humoral xenograft rejection.

BACKGROUND: Transgenic pigs expressing human decay accelerating factor (hDAF) have been widely used as donors in various non-human primate transplant models. Despite the use of similar immunosuppressive protocols, there is marked variation in graft survival among centres. The present study was undertaken to determine whether the level of hDAF expression in the pig kidney correlates with the degree of rejection and duration of graft survival. METHODS: hDAF transgenic pigs were provided from two suppliers: Guelph Imutran Centre (G) and Harlan Sprague Dawley (H). Following a bilateral nephrectomy, a single hDAF pig kidney was implanted in the baboon, which was subsequently treated with conventional immunosuppressive protocols. The pig's contralateral kidney was collected to provide baseline data. The severity of acute humoral xenograft rejection (AHXR) was graded as stage I-III. hDAF expression was measured using morphologic analysis comparing the contralateral and grafted kidneys at the endpoint. RESULTS: Baseline hDAF expression in kidneys from pigs provided by supplier G was significantly higher than that from supplier H (P<0.01). Furthermore, the survival of baboons receiving grafts from G pigs was significantly longer than those receiving grafts from H pigs (P<0.05). In addition, reduction of hDAF expression at the endpoint was associated with a higher degree of AHXR. Severe apoptosis or necrosis was found in grafts with AHXR II-III. CONCLUSIONS: Pig kidneys from different suppliers have variable baseline hDAF expression, which may have an influence on graft survival. Reduced expression of hDAF in the terminal graft was associated with the severity of rejection.

Acute Disease↗

PubMed2005

Effects of human papillomavirus type 16 E7 protein on the growth of cervical carcinoma cells and immuno-escape through the TGF-beta1 signaling pathway.

OBJECTIVE: E7 is regarded as one of the main oncoproteins of high-risk human papillomaviruses (HPVs). It may affect the transforming growth factor beta 1 (TGF-beta1) signaling pathway. In this study, the relationship between HPV-16 infection and the functions of three critical factors of the TGF-beta1/Smads pathway was explored to assess the possible role of E7 in the development of cervical cancer. METHODS: The expression of E7, TGF-beta1, TbetaR-II and Smad4 was detected by immunohistochemistry in paraffin-embedded cervical samples, and by RT-PCR and Western blotting in cervical cancer cell lines. The effect of TGF-beta1 on the growth of cervical cancer cells were tested by methyl thiazolyl tetrazolium (MTT), and the effects of HPV-16 E7 protein on normal and malignant cervical cells were investigated by flow cytometry. RESULTS: During the progression from benign to malignant lesions, the expression levels of TGF-beta1 and Smad4 increased significantly in cervical carcinoma tissues. The expression of TGF-beta1 was positively correlated with E7 expression. In vitro experiments showed that TGF-beta1 could not inhibit the proliferation of several cervical carcinoma cell lines in long-term regulation, but could inhibit immunologic reactions of peripheral blood mononuclear cells (PBMCs). Blocking E7 expression could lower the expression level of TGF-beta1 and induce cells to enter apoptosis. CONCLUSIONS: Our data indicate that HPV-16 E7 protein plays an important role during the development of cervical cancer by immuno-inhibition and stimulation of tumor cell proliferation through the TGF-beta1/Smads signaling pathway.

Cell Growth Processes↗

PubMed2005

Theoretical models and analytic expressions for buildup time of pulsed confocal unstable optical parametric oscillators with uniform or Gaussian reflectivity mirrors.

A theoretical model and a simplified analytic expression are developed to describe the buildup time of a pulsed confocal unstable optical parametric oscillator (OPO) with a uniform-reflectivity mirror (URM) or a Gaussian-reflectivity mirror (GRM). Two analytic expressions have been demonstrated to correspond to theoretical models with a sufficient degree of accuracy. The effects of a variety of cavity and pump parameters on the buildup time of an OPO were investigated and analyzed. It was found that a GRM unstable OPO generally exhibits a shorter buildup time than the corresponding URM unstable OPO with equally effective output coupling.

Journal Article↗

PubMed2005

Reversing chemoresistance in cisplatin-resistant human ovarian cancer cells: a role of c-Jun NH2-terminal kinase 1.

To investigate the role of activation of c-Jun NH2-terminal kinase 1 (JNK1) in mediating cisplatin-induced apoptosis and the possibility of induction of JNK activity in triggering relation to DNA damage and drug resistance. We investigated the difference of cisplatin-induced activation of JNK pathway and H2O2 alteration between cisplatin-sensitive human ovarian carcinoma cell line A2780 and its resistant variant A2780/DDP. JNK, p-JNK protein, and extracellular H2O2 levels were determined in both A2780 and A2780/DDP cells which were transfected with dominant negative allele of JNK and recombinant JNK1 separately. Both A2780 and A2780/DDP were treated with CDDP, the JNK pathway was activated and a prolonged JNK activation was maintained for at least 12 h in A2780, and only a transient activation (3 h) was detected in A2780/DDP in response to cisplatin treatment. Inhibition of JNK activity by transfection with a dominant negative allele of JNK blocked CDDP-induced apoptosis significantly in A2780 cells. Selective stimulation of the JNK pathway by lipofectamine-mediated delivery of recombinant JNK1 led to activation of c-Jun and decrease of extracellular H2O2, as well as apoptosis sensitization to CDDP in A2780/DDP cells. We concluded that JNK pathway might play an important role in mediating cisplatin-induced apoptosis in A2780 cells, and the duration of JNK activation might be critical in determining whether cells survive or undergo apoptosis. The resistance to CDDP can be reversed through activating c-Jun and decreasing extracellular generation of H2O2 by pcDNA3(FLAG)-JNK1-wt transfection in A2780/DDP cells.

Antineoplastic Agents↗