我国欠发达地区民营企业家成长环境研究

民营企业家的生成模式可以分为外援生成和内生生成两种。从外援生成来看,扶贫没有形成欠发达地区的内生能力,内迁企业也无法“催生”大量的民营企业家;从内部来看,封闭性的文化及山区地形造成的市场分割,以及人力资本和物质资本的大量外流,大大削弱了欠发达地区内生民营企业家的土壤。但是,外援生成模式的低效性决定了欠发达地区的民营企业家成长模式应该以内生为主。

Inhibitory effect of arsenic trioxide on angiogenesis and expression of vascular endothelial growth factor in gastric cancer

AIM: To investigate the inhibitory effect of As2O3 on angiogenesis of tumor and expression of vascular endothelial growth factor (VEGF) in tumor cells in vivo and in vitro. METHODS: The solid tumor model was formed in nude mice with the gastric cancer cell line SGC-7901. The animals were randomly divided into three groups. As2O3 was injected into the arsenic-treated groups (2.5 mg/kg and 5 mg/kg) and the same volume of saline solution was injected into the control group. Microvessel density (MVD) and expression of VEGF were detected with immunofluorescence laser confocal technology. Further expression of VEGF protein and VEGF mRNA was measured with Western bloting and fluorescence quantitative RT- PCR in SGC-7901 cells treated with As2O3. RESULTS: In nude mice, after treatment with 5 mg/kg and 2.5 mg/kg As2O3 respectively, about 50% and 30% tumor growth inhibition were observed correspondingly (P < 0.05, P < 0.05). Decrease in MVD appeared in As2O3-treated tumors compared with control group (P < 0.001, P < 0.001). MVD in tumors was significantly lower in 5 mg/kg group than in 2.5 mg/kg group (P < 0.01). The fluorescence intensity levels of VEGF in tumor cells were significantly lowered in the arsenic-treated groups (P < 0.01, P < 0.01). The fluorescence intensity level of VEGF in 5 mg/kg group was lower than that in 2.5 mg/ kg group (P < 0.01). In vitro, the expression of VEGF protein decreased in dose- and time-dependent manner after the treatment with As2O3, but in VEGF mRNA no significant difference was found between the control group and the treated groups. CONCLUSION: As2O3 can inhibit solid tumor growth by inhibiting the formation of new blood vessels. One of the mechanisms is that As2O3 can inhibit VEGF protein expression.

Increased expression of angiogenin in gastric carcinoma in correlation with tumor angiogenesis and proliferation

AIM： To investigate the implication of angiogenin （ANG） in the neovascularizaton and growth of human gastric carcinoma （HGC）. METHODS： ANG mRNA expression in HGC specimens obtained by surgical resection from patients with HGC were examined by RT-PCR. ANG, Ki-67, VEGF protein expression and microvessel density （MVD） in HGC specimens were detected by immunohistochemistry. RESULTS： RT-PCR showed significantly higher ANG mRNA expression （0.482 ± 0.094） in HGC tissues than in the surrounding nontumorous tissues （0.276 ±0.019, P = 0.03）. MVD within tumorous tissues increased significantly with ANG mRNA expression （r = 0.380, P = 0.001） and ANG protein expression （P 〈 0.01）. The ANG expression levels of cancer tissues were positively correlated with VEGF （P 〈 0.01） and the proliferation index of cancer cells （P 〈 0.01）. CONCLUSION： ANG is one of the neovascularization factors of HGC. ANG may work in coordination with VEGF, and promote the proliferation of HGC cells.

Expression of vascular endothelial growth factor-C and angiogenesis in esophageal squamous cell carcinoma

AIM： To investigate the expression of vascular endothelial growth factor-c （VEGF-C） mRNA and microvessel density （MVD） in human esophageal squamous cell carcinoma （ESCC） and its relationship with clinical significance. METHODS： Specimens obtained from 43 patients undergoing surgical resection for ESCC were used in this study. The expression of VEGF-C mRNA was examined by in situ hybridization. Tumor MVD was determined immunohistochemically with anti-CD31 antibody and estimated by image analysis. Ten sections of adjacent normal mucosa were also examined. RESULTS： VEGF-C mRNA expression was detected in cytoplasm of carcinoma cells. Of the 43 ESCC patients studied, 18 cases （41.9%） were positive for VEGF-C mRNA. No VEGF-C mRNA expression was observed in normal esophageal mucosa. VEGF-C mRNA expression correlated significantly with lymph node metastasis, TNM stage and depth of invasion （P 〈 0.05）. Furthermore, histological grade （differentiation） tended to correlate with VEGF-C mRNA expression, but was not statistically significant （P 〉 0.05）. In tumor lesions, the MVD was significantly greater than that in normal esophageal mucosa. MVD correlated significantly with lymph node metastasis, TNM stage and depth of invasion （P 〈 0.05）, but not with histological grade （differentiation） （P 〉 0.05）. Lesions with VEGF-C mRNA expression had a significantly higher MVD than that of those without VEGF-C mRNA expression （P 〈 0.05）. CONCLUSION： VEGF-C plays a role in lymphatic metastasis via lymphangiogenesis and angiogenesis in ESCC. VEGF-C is one of the important predictors of the biological behavior in ESCC.

Study of relationship between VEGF expression and vasculogenic mimicry of tumor

Objective： The aim of this study was to explore the relationship between VEGF expression and vasculogenic mimicry of tumor in vitro. Methods： We observed the ability to form vasculogenic mimicry in several cell lines follow as LO2 cell, hepG2 cell, SMMC-7721 cell and A549 cell in three-dimensional cultures; we detected the expression of VEGF in the level of mRNAand protein by polymerase chain reaction （PCR） and western blot in those cell lines. Results： HepG2 cell and A549 cell had the ability to form vasculogenic mimicry in three-dimensional cell cultures, while LO2 cell and SMMC-7721 cell hadn＇t the ability. The rates of VEGF16JGAPDH were 0.212 ± 0.011,0.208 ± 0.013, 0.117 ± 0.009 and 0.214±0.012 respectively, and the rates of VEGF121/GAPDH were 0.186 ± 0.018, 0.192± 0.014, 0.050 ± 0.010, 0.196 ± 0.017 in LO2 cell, hepG2 cell, SMMC-7721 cell and A549 cell, separately. The expression of VEGF gene in mRNA and protein levels in HepG2 cell, LO2 cell and A549 cell were significantly higher than that in SMMC-7721 cell （P 〈 0.05）. Conclusion： The cell lines which the expression of VEGF gene is low don＇t have the ability to form vasculogenio mimicry and the high expression of VEGF gene cann＇ t form vasculogenic mimicry at all, while the expression of VEGF gene in the cell lines is high in the cell lines which can form vasculogenic mimicry. VEGF has impact on the formation vasculgenic mimicry. Only the cells which the expression of VEGF is high have the potential to form vasculogenic mimicry. But, it doesn＇t play a unique key role in vasculogenic mimicry.

Vascular endothelial growth factor promotes angiogenesis in gastric carcinoma

Objective: To explore the role of vascular endothelial growth factor (VEGF) in the angiogenesis and development of human gastric carcinoma. Methods: The expressions of VEGF and its receptor KDR (ki-nase-domain insert containing receptor) in human gastric cancer tissue and SGC-7901 cells were detected with immunohistochemical staining. Microvessel density (MVD) was obtained after immunostaining for Factor-VIII. VEGF in SGC-7901 cell line was detected with Western blot. VEGF levels were manipulated in human gastric cancer cell by using eukaryotic expression vector containing the complete VEGF165 complimentary DNA in either the sense or antisense orientation. Finally the biological characteristics of the transfectants were identified. Results: VEGF-positive rate in TNM grade I and IV gastric carcinomas (19. 0%) were significantly higher than that in grade I and I (72. 4%) (P<0. 05). Increased MVD was found in VEGF-positive tumors (16. 4±6. 7). which is significantly larger than in VEGF-negative tumors (6. 5±2. 1) (P< 0. 05). Human gastric cancer cells (SGC-7901) produced 3 kinds of VEGF in molecule. In 2 cases of 50 specimens, a few gastric cancer cells expressed KDR in cytoplasm and cell membranes. SGC-7901 cells with anti-sense VEGF165 showed a significant reduction in cell surface VEGF protein with the immunofluorescence intensity from 8. 9% to 31. 6% (P<0. 05). However, those with stable integration of VEGF165 in the sense orientation resulted in an increase in cellular and cell surface VEGF with the immunofluorescence intensity from 75. 4% to 31. 6% (P<0. 05). The decrease of VEGF levels was associated with a marked decrease in the growth of nude mouse xenografted tumor (33 d post-implantation, 345. 4±136. 3 mm3 in size) (P<0. 05 vs control SGC-7901 group) , whereas VEGF overexpression resulted in an increase of xenografted tumor size (33 d post-implantation, 2 350. 5±637. 7 mm3 in size) (P<0. 05 vs control SGC-7901 group). Conclusion: VEGF plays an important role in the development of human gastric cancer, and might have an autocrine effect upon the gastric cancer cells. The inhibition of VEGF by antisense RNA expression might prevent solid tumor from growing and metastasizing.

Identification of colorectal cancer metastasis markers by an angiogenesis-related cytokine-antibody array

AIM： To investigate the angiogenesis-related protein expression profile characterizing metastatic colorectal cancer （mCRC） with the aim of identifying prognostic markers.METHODS： The expression of 44 angiogenesis- secreted factors was measured by a novel cytokine antibody array methodology. The study evaluated vas- cular endothelial growth factor （VEGF） and its soluble vascular endothelial growth factor receptor （sVEGFR）-I protein levels by enzyme immunoassay （EIA） in a panel of 16 CRC cell lines, mRNA VEGF and VEGF-A isoforms were quantified by quantitative reverse-transcription polymerase chain reaction （Q-RT-PCR） and vascular en- dothelial growth factor receptor （VEGFR）-2 expressionwas analyzed by flow cytometry.

Expressions of MVD, VEGF, Ki67 in Residual Prostate Cancer after Cryoablation

OBJECTIVE To analyze the effects of cryoablation on the mice bearing Rm-I prostate cancer through detecting tumor angiogenesis and cancer cell proliferation in the mice after cryoablation, and to explore the effects of cryoablation on vascular endothelium growth factor （VEGF）, Ki67 protein expression and microvessel density （MVD） in the mice bearing prostate cancer. METHODS Sixty Rm-1 mouse models of prostate cancer were established. Experimental mice were randomized into 2 groups： the cryoablation group （n = 30） and the control group （n = 30）. After file therap）4 tumor tissues of the mice in group A and B were obtained at day 0 （without cryoablation）, 1st, 3rd, 5th, 7th, 14th day, respectivelj6 after cryoablation, and the expressions of MVD, VEGF and Ki67 proteins were detected at the same time points. RESULTS The expressions of MVD, VEGF and Ki67 proteins in group A were decreased. The lowest values of the factors were detected on the 3rd day after cryoablation, and increased slowly after that. The expressions of MVD, VEGF and Ki67 proteins in the control group were not changed. Significant changes of the expressions of MVD, VEGF and Ki67 proteins in the group A were found at different time points. Correlation analysis suggested a positive correlation between the expressions of VEGF and MVD proteins （r = 0.8793）, a positive correlation between the expressions of Ki67 and MVD proteins （r = 0.7614）, and a positive correlation between the expressions of VEGF and ki67 proteins （r = 0.6921）. CONCLUSION After argon-helium cryoablation treatment for the mice bearing prostate cancer, the expressions of MVD, VEGF and Ki67 proteins in local tumor were reduced on the 1st day. The lowest values of the factors were detected on the 3rd day after cryoablation, and then increased after that. Cryoablation combined with other modalities of treatment may effectively improve the treatment effects of cryoablation for prostate cancer.

Correlation of VEGF expression,angiogenesis and carcinomatous change in breast tumors

Objective: The aim of the study was to detect the expression of vascular endothelial growth factor (VEGF) and microvessel density (MVD) in breast benign tissues and malignant tumors to clarify the relationship between VEGF expression, angiogenesis and breast carcinoma occurrence. Methods: The expression of VEGF and MVD in 79 cases of invasive ductal breast carcinoma, 79 corresponding para-cancer normal tissues from primary invasive breast carcinomas, 35 breast carcinoma in situ, 23 breast atypical hyperplasia and 56 breast fibroid tumor were examined by immunohistochemistry staining (SP-method). Results: The positive rate of VEGF and MVD value increased significantly with the increase of the malignant degree of breast tissues (P = 0.000). In breast carcinoma group, the positive rate of VEGF and MVD value with lymph node metastasis were higher than those without lymph node metastasis (P = 0.011 and P = 0.023). A significant higher expression of VEGF and MVD value were observed as the clinical stage increased (P = 0.035 and P = 0.012). The MVD value was higher in VEGF positive group than negative group (P = 0.000). Conclusion: The combining detection of VEGF expression and MVD is helpful for evaluating malignant degree of breast carcinoma. Angiogenesis in breast tumors and occurrence of breast carcinoma might be correlated with the expression of VEGF.

The expression of HIF-1α and VEGF as well as their correlation with angiogenesis in esophageal squamous cell carcinomas

Objective： To investigate the correlations among the expressions of hypoxia-inducible factor-1α （HIF-1α）, vascular endothelial cell growth factor （VEGF） and microvessel density （MVD）, and their relationships to the clinicopathologic characteristics of esophageal squamous cell carcinomas （ESCC）. Methods： The expressions of HIF-1α, VEGF and MVD were detected by immunohistochemical method in 45 cases of ESCC, 30 intraepithelial neoplasia and 35 normal esophageal mucosal epithelia tissues. The correlations among the expressions of HIF-1α, VEGF and MVD, and their relationships to the clinicopathologic features of ESCC were analyzed. Results： The rate of positive expression of HIF-1α and VEGF which were 80% and 84% in ESCC were significantly higher than those in intraepithelial neoplasia and normal esophageal mucosal epithelium tissues （P 〈 0.01） and so did the MVD value which was71.10 ±15.02 in ESCC （P 〈 0.01）. The expression of HIF-1α and VEGF were positively correlated with the depth of tumor invasion, lymph node metastasis and TNM staging of ESCC. The expressions of HIF-1α were positively correlated with the expressions of VEGF and the value of MVD. Conclusion： Overexpression of HIF-1α is found in ESCC. HIF-1α may induce the angiogenesis in ESCC by upregulating the transcription of VEGF gene. It may play an important role in the carcinogenesis and aggression in ESCC, HIF-1α, VEGF and MVD may be a useful marker for evaluating the biological behaviors of ESCC.

Angiogenesis at Different Stage of Pregnancy Ingoatplacenta

The increase intransplacental exchange depends primarily on the great development of the placental vascular bed. The aim of this study was to evaluate the pattern of placental vascular development at day 50 and 100 of pregnancyin goats and the relationship with the vascular endothelial growth factor （VEGF） immunolocalization. The placental morphometric variables： capillary area density, capillary perimeter density, capillary number density and average capillary perimeter of the caruncular （CAR） and cotyledonary （COT） tissues were measured at day 50 （n = 5） and 100 （n = 5） of gestation. Also, the immunolocalization of VEGF was performed. In the CAR and COT tissues a significant increase of capillary area density and capillary perimeter density at day 100 of the gestation was observed. In the COT tissue, this was due to the increase in the capillary number density; however in the CAR tissue this was due to the increase in the capillary size. We can conclude that in both tissues there were different strategies to increase the capillary area and, thereby, the nutrients exchange. The immunolocalization of VEGF in the COT tissue showed the endothelial cells of blood vessels and trophoblastcells surrounding the villi intensely inmunostained, which would indicate the involvement of VEGF in the placental vascular development.

RNA interference against hypoxia inducible factor-1α inhibited growth of cervical cancer by limiting vascularization

Objective:Cervical cancer has become a major public health problem.The development of effective,systemic therapies for cervical cancer is highly desired.We show here that hypoxia inducible factor-1α(HIF-1α) was indicated as an attractive therapeutic molecular target for cervical cancer.Methods:Firstly,we observed the expressional level of HIF-1α in cervical cancer and Hela and Siha cell lines.Secondly,by constructuring HIF-1α shRNA targeting human HIF-1α mRNA common sequence and transfecting it with plasmid to cervical cell,we detected the changes of HIF-1α and its downstream genes levels VEGF.Then we injected selected stably transfected cell line into athymic nude mice to estimate its' antitumor effects.Results:We observed that HIF-1α inhibition was related to down-regulated VEGF resulting in prevention of angiogenesis,then leading to slower-growing tumors.Conclusion:The underlying concept of transfecting a HIF-1α shRNA expression vector to block the HIF-1α holds promise as the clinical potential of gene therapy for cervical cancer.

Extracellular domain of kinase domain region mediated by adeno-associated virus inhibits growth and angiogenesis of bladder cancer in Balb-c mice

OBJECTIVE: To verify whether the extracellular domain of kinase domain region (KDR) has anti-angiogenesis activity in vivo. METHODS: cDNA was cloned into adeno-associated virus (AAV) vector pSNAV and transfected to baby hamster kidney (BHK) cells. Recombinant AAV was obtained from the cell culture supernatant after adding helper virus. Recombinant AAV-infected human bladder cancer EJ cell line (EJ cells) were injected subcutaneously into Balb-c nude mice. Tumor specimens were removed from the mice, paraffin-embedded and sliced, then stained by immunohistochemistry. Microvessel density (MVD) was determined under a microscope. RESULTS: The tumor volume developed by EJ cells transfected with the extracellular domain of KDR was significantly smaller (1.70 +/- 0.18 cm(3)) compared with that in the control (5.62 +/- 0.67 cm(3)) (P

Cytocompatibility of regenerated silk fibroin film:a medical biomaterial applicable to wound healing

Objective： To explore the feasibility of using regenerated silk fibroin membrane to construct artificial skin substitutes for wound healing, it is necessary to evaluate its cytocompatibility. Methods： The effects of regenerated silk fibroin film on cytotoxicity, adhesion, cell cycle, and apoptosis of L929 cells, growth and vascular endothelial growth factor （VEGF） expression of ECV304 cells, and VEGF, angiopoietin-1 （Ang-1）, platelet-derived growth factor （PDGF） and fibroblast growth factor 2 （FGF2） expression of WI-38 cells were assessed by 3-（4,5）-dimethylthiahiazo （-z-yl）-3,5-di-phenytetrazoliumromide （MTT） assay, viable cell counting, flow cytometry （FCM）, and enzyme-linked immunosorbant assay （ELISA）. Results： We showed that the regenerated silk fibroin film was not cytotoxic to L929 cells and had no adverse influence on their adhesion, cell cycle or apoptosis; it had no adverse influence on the growth and VEGF secretion of ECV304 cells and no effect on the secretion of VEGF, Ang-1, PDGF and FGF2 by WI-38 cells. Conclusion： The regenerated silk fibroin film should be an excellent biomaterial with good cytocompatibility, providing a framework for reparation after trauma in clinical applications.

Overweight and obesity versus concentrations of VEGF-A, sVEGFR-1, and sVEGFR-2 in plasma of patients with lower limb chronic ischemia

Objective： Being overweight or obese comprises a significant risk factor for atherosclerosis. Fat tissue also generates factors stimulating angiogenesis, the process by which new blood vessels form. The purpose of this paper is to assess concentrations of the vascular endothelial growth factor A （VEGF-A） and its soluble type-1 and type-2 re- ceptors （sVEGFR-1 and sVEGFR-2） in plasma of patients with peripheral arterial disease （PAD） depending on the level of nutrition according to body mass index （BMI）. Methods： The study group included patients suffering from symptomatic PAD （n=46） in Fontaine classes Ila-lV without any history of neoplastic disease and who have a normal BMI （n=15）, are overweight （n=21） or are obese （n=10）. The control group （n=30） consisted of healthy non-smoking volunteers who were neither overweight nor obese. Venous blood plasma samples were collected from both groups at rest in the morning to determine plasma concentrations of VEGF-A, sVEGFR-1, and sVEGFR-2 using the enzyme- linked immunosorbent assay （ELISA） method. Results： The group of patients with PAD co-existent with being over- weight or obese tended to have higher mean concentration levels of VEGF-A and sVEGFR-2 when compared with patients suffering from PAD with normal BMIo A statistically significant positive correlation was obtained between BMI and average plasma concentrations of sVEGFR-2 （R=0.37, P=-0.0103）. However, no significant correlation was no- ticed between BMI and VEGF-A or sVEGFR-1 concentrations. Conclusions： A positive correlation determined be- tween the level of antiangiogenic factor and BMI value may be indicative of the linearly growing prevalence of some antiangiogenic factors in patients with metabolic disorders, which may be one of numerous factors contributing to incomplete efficiency of collateral circulation development in patients with PAD.