血管内皮细胞生长因子对肾小球内皮细胞通透性的影响

目的 :观察血管内皮细胞生长因子 (VEGF)对肾小球内皮细胞通透性的影响 ,并与脐静脉内皮细胞进行比较分析。　 方法 :采用二室弥散系统检测内皮细胞通透性。肾小球内皮细胞 (MGEC)和人脐静脉内皮细胞(HUVEC)接种于细胞培养嵌套的微孔滤膜 (孔径 0 4 5 μm)上 ,待细胞生长融合后 ,加入不同浓度的VEGF作为处理因素 ,以生物素标记的牛血清白蛋白 (biotin BSA)作为通透性指示剂 ,采用ELISA方法检测不同时间段biotin BSA通过细胞单层的百分数。　 结果 :正常培养条件下 ,生长在滤膜上的MGEC和HUVEC单层的通透性没有明显差异。VEGF可显著增加MGEC和HUVEC的通透性 ,呈剂量和时间依赖性。 1μg/LVEGF作用 12h可使MGEC对白蛋白的通透率增加近 2 5 % (0 31± 0 0 3vs 0 2 5± 0 0 3) ;VEGF浓度达 10 μg/L始显著增加HUVEC通透性 (0 2 8± 0 0 7vs0 2 1± 0 0 4 ) ,且远小于MGEC通透性增加的幅度 (P <0 0 1) ;VEGF浓度达 5 0 μg/L时 ,其增加内皮细胞通透性的作用基本达到饱和。 5 0 μg/LVEGF作用 0 5h即可使MGEC和HUVEC的蛋白通透率分别增加 10 0 % (0 12± 0 0 2vs0 0 6± 0 0 1)和 6 0 % (0 0 8± 0 0 3vs0 0 5± 0 0 1) ,并至少持续到 12h。　 结论 :首次在体外直接证实了VEGF具有增加MGEC     

A Comparison between the Effects of Secretin and Histamine on the Gastric Secretion of Pepsin in Man

The stimulating effect on the gastric secretion of pepsin of an intravenous injection of one clinical unit of pure secretion per kg body weight was compared to the effect of a subcutaneous injection of 50 μg histamine dihydrochloride per kg body weight in the same series of subjects. The pattern of the pepsin response differed markedly. The ratio between the amounts of pepsin and HCl secreted decreased after injection of histamine, whereas it increased after injection of secretin. The effect of secretin on the pepsin/HCl ratio lasted for about two hours.     

Pathways of macromolecular extravasation across microvascular endothelium in response to VPF/VEGF and other vasoactive mediators

OBJECTIVE: The goal of these studies was to define the anatomic pathways by which circulating macromolecules extravasate from the hyperpermeable microvessels that supply tumors and from normal venules that have been rendered hyperpermeable by vasoactive mediators. METHODS: Extravasation pathways of circulating macromolecular tracers were followed by several morphological techniques: light and fluorescence microscopy, transmission electron microscopy of routine as well as ultrathin and serial sections, computer-assisted three-dimensional reconstructions, and morphometry. RESULTS AND DISCUSSION: Macromolecules extravasated across tumor microvessels or across normal venules rendered hyperpermeable by VPF/VEGF, histamine, or serotonin by three primary pathways: 1) Vesiculo-vacuolar organelles (VVOs), clusters of cytoplasmic vesicles and vacuoles that span endothelial cytoplasm from lumen to ablumen; 2) trans-endothelial cell (EC), pores, and 3) fenestrae. We also present data concerning the structure and function of VVOs as well as evidence that VVOs form as the result of linking together and fusion of caveolae-sized unit vesicles. Under suitable conditions VVOs also afforded a pathway for macromolecular transport in the reverse direction, i.e., from vascular ablumen to lumen. Finally, in addition to opening VVOs to the passage of macromolecules, mediators such as VPF/VEGF may also induce structural rearrangements of VVOs, transforming them into trans-EC pores or fenestrae.     

An Engineered Heparin-Binding Form of VEGF-E (hbVEGF-E). Biological effects in vitro and mobilizatiion of precursor cells

Vascular endothelial growth factor (VEGF-A) is the founding member of a family of angiogenic proteins with various binding abilities to three cognate VEGF receptors. Previously, a gene encoding from the genome of parapox orf virus (OV) with about 25% amino acid identity to mammalian VEGF-A was named VEGF-E and shown to bind and specifically activate the vascular endothelial growth factor receptor VEGFR-2 (KDR/flk-1). Here, we have generated a novel heparin-binding form of VEGF-E by introducing the heparin-domain of the human VEGF-A(165) splice variant into the viral VEGF-E protein. Recombinant heparin-binding VEGF-E (hbVEGF-E) is shown to stimulate proliferation and sprout formation of macro- and microvascular endothelial cells to a similar extent as the parental OV-VEGF-E but fails to activate peripheral mononuclear cells. However, hbVEGF-E is more potent in binding competition assays with primary human endothelial cells when compared to the OV-VEGF-E. This can be explained by our finding that binding of hbVEGF-E but not of parental OV-VEGF-E to the VEGFR-2 is strongly increased by the addition of neuropilin-1 (NP-1), a cognate co-receptor for VEGF-A. The engineered hbVEGF-E was compared with the VEGFR-1 selective and also heparin-binding form of placenta growth factor (PlGF-2) in vivo. Both heparin-binding homologues induced mobilization of endothelial progenitor cells from the bone marrow and gave rise to similar colony numbers of myeloic cells in a colony-forming assay. These findings suggest that both VEGFR-1 and VEGFR-2 are involved in stem cell mobilization.     

Comparative study of isoflavone,quinoxaline and oxindole families of anti-angiogenic agents

A study designed to compare the effects on VEGF-induced angiogenesis of a number of known anti-angiogenic agents together with some novel derivatives thereof was undertaken. Thus the isoflavone biochanin A 1, indomethacin 2, the 3-arylquinoxaline SU1433 and its derivatives 3–6, the benzoic acid derivative 7, the oxindoles SU5416 8 and SU6668 11, together with their simple N-benzyl derivatives 9, 10, and 12 were selected for study. Using an in vitro assay the compounds were evaluated for their ability to inhibit VEGF-induced angiogenesis in HUVECs, and the cytotoxicity of representative compounds was also studied in tumour cell lines using 24-h exposure. The results indicate that the SU compounds, SU1433, SU5416 and SU6668, are more potent inhibitors of VEGF-induced angiogenesis than indomethacin or the naturally occurring biochanin A, presumably because they inhibit VEGF receptor signalling. Blocking one of the phenolic OH groups of SU1433 reduced anti-angiogenic activity, as did blocking the NH groups of SU5416 and SU6668. Cytotoxicity studies indicate that none of the compounds examined exhibited cytotoxicity at anti-angiogenic concentrations.     

The crucial role of vascular permeability factor/vascular endothelial growth factor in angiogenesis: a historical review

Angiogenesis is a biological process by which new capillaries are formed and it occurs in many physiological and pathological conditions. It is controlled by the net balance between molecules that have positive and negative regulatory activity and this concept had led to the notion of the 'angiogenic switch', depending on an increased production of one or more of the positive regulators of angiogenesis. Numerous inducers of angiogenesis have been identified and this review offers a historical account of the relevant literature concerning the discovery of one of the best characterized angiogenic factors, namely vascular endothelial growth factor (VEGF)/vascular permeability factor. Moreover, different strategies, designed to stimulate and to inhibit VEGF production in the context of several potential therapeutical implications, are discussed.     

Effect of serum from patients with idiopathic thrombocytopenic purpura on cultured endothelial cell growth

This study examined the effects of platelet-derived serum factors from patients with idiopathic thrombocytopenic purpura (ITP) on human umbilical cord vascular endothelial cell growth and DNA synthesis. Vascular endothelial cell growth factors were identified in the platelet extracts, and platelet-derived vascular endothelial cell growth factors with molecular weights of less than 10,000 were also identified in the sera. These growth factors were stable even after 30 minutes of heat treatment at 56 degrees C and acid treatment. When ITP patient serum was added to vascular endothelial cells, their growth capacity and DNA synthesis capacity were lower than when serum from normal subjects or patients with ITP in remission was added. This indicated that in ITP, impairment of vascular integrity and abnormal repair of the vascular walls that accompany thrombocytopenia may be causes of the predisposition to hemorrhage. The decrease in ITP of platelet-derived vascular endothelial cell growth factors with molecular weights of less than 10,000 was hypothesized to be a contributory factor.     

局部振动对雄性兔生殖内分泌激素及阴茎组织VEGF mRNA表达的影响

目的通过对雄性新西兰兔血清中生殖内分泌激素、阴茎组织中血管内皮生长因子（VEGF）mRNA的表达,探讨局部振动对雄性兔性功能的影响。方法将新西兰兔30只随机分为观察组（A、B、C组各8只）和对照组（6只）,观察组给予不同强度的振动,对照组不接触振动。分别在接振前和接振第10、20、30天采用ELISA法检测各组血清睾酮（T）、黄体生成素（LH）和雌二醇（E2）的浓度。接振第30天采用荧光定量PCR法检测阴茎组织中VEGFmRNA表达。结果与接振前和对照组比较,C组在接振第30天血清T显著降低（P〈0.05）。与对照组比较,A、B、C3组接振30d后阴茎组织中VEGFmRNA表达显著增强,差异有统计学意义（P〈0.01）。结论局部振动可引起血清T、LH、E2浓度和阴茎组织中VEGFmRNA的表达改变,从而影响性功能。     

VEGF与VEGF-C蛋白在胆管癌中的表达及意义

目的探讨VEGF与VEGF-C蛋白在胆管癌的表达及其与临床病理特征的关系。方法采用免疫组化SP法检测49例胆管癌组织中vEGF与VEGF-C叠白的表达。结果胆管癌VEGF和VEGF—C蛋白的表达率分别为65．3％和69．4％。VEGF和VEGF-C蛋白的高表达与胆管癌淋巴结转移及分化程度有关。VEGF与VEGF—C的表达有显著相关性（P＜0．01）。结论VEGF和VEGF—C蛋白的表达与胆管癌侵袭转移有关。     

Effect of Medical Vagotomy on Acid and Pepsin Responses to Histamine and Pentagastrin in Man

Acid and pepsin secretion in response to graded doses of pentagastrin (ICI 50123) and histamine was studied before and after medical vagotomy in six duodenal ulcer patients.

Before medical vagotomy the mean maximal pepsin response to pentagastrin was reached at a dose causing a submaximal rate of acid secretion, whereas maximal responses of acid and pepsin to histamine occurred at the same doses.

Vagotomy reduced acid and pepsin responses to pentagastrin and histamine at all dose levels and shifted the dose response curve to the right.     

Angiotensin converting enzyme inhibition reduces retinal overexpression of vascular endothelial growth factor and hyperpermeability in experimental diabetes

Aims/hypothesis. Angiotensin converting enzyme (ACE) inhibition has been recently suggested to have retinoprotective actions in diabetic patients but the mechanism of this effect is not known. In vitro, angiotensin II stimulates expression of vascular endothelial growth factor (VEGF), a permeability-inducing and endothelial cell specific angiogenic factor which has been implicated in the pathogenesis of diabetic retinopathy in humans and in experimental animals. We sought to determine the effects of ACE inhibition on retinal VEGF expression and permeability in experimental diabetic retinopathy.¶Methods. Streptozotocin-induced diabetic rats and control animals were assigned at random to receive ACE inhibitor treatment or vehicle. At 24 weeks the retinal VEGF protein gene expression was assessed by northern blot analysis and in situ hybridisation. Retinal permeability to albumin was measured using a double isotope technique.¶Results. Experimental diabetes was associated with cell specific two to fourfold increase in retinal VEGF protein gene expression (p < 0.01) and a 2-fold increase in retinal vascular permeability to albumin (p < 0.01). The localization of VEGF expression in the retina was not altered in animals with experimental diabetes. Angiotensin converting enzyme inhibitor treatment of diabetic rats reduced diabetes-associated changes in VEGF gene expression and vascular permeability.¶Conclusion/interpretation. These findings implicate the renin-angiotensin system in the VEGF overexpression and hyperpermeability which accompany diabetic retinopathy and provide a potential mechanism for the beneficial effects of ACE inhibition in diabetic retinal disease. [Diabetologia (2000) 43: 1360–1367]     

巨噬细胞移动抑制因子对结肠癌HT-29细胞增殖和血管生成因子表达的影响

目的研究巨噬细胞移动抑制因子(MIF)在体外对人结肠癌细胞HT-29增殖及VEGF和IL-8表达的影响。方法分别用25、50、100μg/L人重组MIF(rhMIF)对细胞进行处理后,采用MTT法检测细胞增殖,RT-PCR检测细胞VEGF、IL-8mRNA含量,ELISA测定细胞培养上清液中VEGF和IL-8的蛋白含量。结果rhMIF作用不同时间后,能够促进HT-29细胞生长,增殖活性随浓度增加、时间延长逐渐上升(P<0.05),呈现量—效、时—效关系。细胞VEGF和IL-8mRNA表达及上清液中VEGF和IL-8蛋白含量均明显增加,存在时间和浓度依赖性(P<0.05)。结论MIF能够促进结肠癌细胞增殖,MIF参与肿瘤血管形成有可能是通过上调VEGF和IL-8的表达发挥作用。     

IP方案化疗对小细胞肺癌患者血清VEGF及内皮抑素的影响

目的 探讨IP方案化疗对小细胞肺癌（SCLC）患者血清血管内皮生长因子（VEGF）及内皮抑素的影响.方法 对45例SCLC患者行IP方案化疗,采用ELISA法检测其化疗前后的血清VEGF、内皮抑素,同时对20例健康对照者进行比较.结果 SCLC患者的血清VEGF、内皮抑素均高于对照者（P均＜0.01）,二者水平与患者的年龄、性别、吸烟与否无关,与临床分期有关（P＜0.05）;临床受益患者化疗后血清VEGF下降、内皮抑素升高（P均＜0.01）;血清VEGF低于平均值组的中位生存期长于高于平均值组,内皮抑素高于平均值组中位生存期长于低于平均值组（P均＜0.05）.结论 SCLC患者血清VEGF及内皮抑素的变化对判定化疗疗效及预后有一定参考价值.     

白三烯受体拮抗剂对致敏大鼠血管内皮生长因子及其受体表达的影响

目的 研究白三烯受体拮抗剂(孟鲁司特)对支气管哮喘(简称哮喘)气道炎症和气道重塑的影响,揭示白三烯受体拮抗剂对血管内皮生长因子(VEGF)及其受体的调控作用.方法 将24只清洁级雄性SD大鼠按随机数字表法分为对照组、哮喘组和干预组,每组8只.对照组采用生理盐水致敏和激发,哮喘组采用卵清白蛋白致敏和激发,干预组在采用卵清白蛋白致敏和激发前给予孟鲁司特灌胃.采用肺功能检测各组大鼠气道呼气阻力;采用酶联免疫吸附法(ELISA)对各组大鼠血清中VEGF和白三烯D<4>(LTD4)进行定量分析;用免疫组织化学方法检测VEGF、VEGF受体1(VEGFR1)及VEGFR:在大鼠肺组织内的表达水平.采用图像分析软件测定肺组织切片中的血管计数、血管平滑肌厚度.结果 (1)肺功能检测显示哮喘组平均呼气阻力显著升高;(2)对照组血清中VEGF和LTD4的水平分别为(17±5)ng/L和(6.1±0.7)ng/L,哮喘组分别为(31±6)ng/L和(10.7±3.5)ng/L,干预组分别为(15±4)ng/L和(9.8±1.6)ng/L,对照组和干预组分别与哮喘组比较差异有统计学意义(F值分别为63.78和39.56,均P<0.01);(3)免疫组织化学结果显示哮喘组VEGF及受体均大量表达,而对照组和干预组有较少表达.(4)图像分析显示,对照组、哮喘组和干预组的血管计数分别为14±2、22±2和16±4.(5)直线相关分析显示,血管计数与血清中VEGF的水平正相关(r=0.705,P<0.05).结论 VEGF及其受体在哮喘气道及肺内过度表达,参与了气道炎症和气道血管重塑的过程.孟鲁司特可能通过影响VEGF及其受体的表达影响气道炎症和气道血管重塑的病理生理过程.     

丁基苯酞对缺血性脑损伤模型大鼠血脑屏障的影响

目的观察大鼠全脑缺血后血脑屏障的改变以及丁基苯酞的干预作用,探讨其对缺血性脑损伤的防护作用机制。方法选择120只SD大鼠,随机分为假手术组24只、脑缺血组24只、丁基苯酞组72只。采用四血管结扎的全脑缺血模型,制模成功后丁基苯酞组大鼠按腹腔注射剂量又分为丁基苯酞0.3 mg/kg组24只、丁基苯酞1.0mg/kg组24只、丁基苯酞3.0 mg/kg组24只;检测脑组织依文思蓝(EB)含量、免疫组织化学法检测脑组织血管内皮生长因子(VEGF)表达、心脏取血计数循环内皮细胞数。结果与假手术组比较,脑缺血组大鼠脑组织EB含量、VEGF表达、循环内皮细胞数明显升高(P<0.05,P<0.01);与脑缺血组比较,丁基苯酞各剂量组大鼠脑组织EB含量、VEGF表达、循环内皮细胞数明显降低,以丁基苯酞3.0 mg/kg组最明显(P<0.05,P<0.01)。结论丁基苯酞通过降低大鼠全脑缺血后脑组织VEGF表达、降低循环内皮细胞数,从而降低血脑屏障的通透性,对缺血性脑损伤有保护作用。     

细胞内活性氧在糖基化终末产物促人腹膜间皮细胞分泌血管内皮生长因子中的作用

目的:观察糖基化终末产物(AGEs)对人腹膜间皮细胞(HPMC)分泌血管内皮生长因子(VEGF)的影响及细胞内活性氧(ROS)在其中的作用。方法:分别用不同浓度的AGE-HSA及抗氧化剂N-酰-L-半胱氨酸(NAC)作用于细胞,用RT-PCR和ELISA方法测定HPMC中VEGF的表达;再以氧化敏感的荧光染料2、7-二氢二氯荧光素(DCFH)染色,流式细胞仪测定细胞内活性氧强度。结果:AGE-HSA能使细胞内ROS水平明显升高,呈现浓度依赖效应;AGE-HSA同时以时效和量效方式促进HPMC中VEGF的表达;而NAC能够明显抑制AGE-HSA所导致的细胞内ROS升高,同时抑制HPMC中VEGF的分泌。结论:AGE-HSA可能部分通过诱导细胞内ROS,促进HPMC表达VEGF,从而引起腹膜新生血管的增加,最终导致腹膜失超滤现象。     

血管内皮生长因子基因转染对犬肾动脉内膜损伤后的作用

目的:观察血管内皮生长因子(VEGF)基因转染肾动脉内膜后的表达,以及对肾动脉内膜损伤后的作用。方法:利用分子生物学技术,将pcD2/VEGF121真核表达质粒及pcD2空载质粒转化大肠杆菌XL1-Blue,大量提取质粒。试验犬14只采用自身对照方法将左右肾动脉随机分为治疗侧和对照侧。行双侧肾动脉造影,将PTCA球囊送入肾动脉中段加压并拉伤动脉内膜,再将涂布pcD2/VEGF121质粒及pcD2空载质粒的球囊分别导入治疗侧及对照侧损伤段动脉加压维持5min,以使基因转染动脉内膜。分别于术后1、6及10周行肾动脉造影后将犬处死,取损伤段肾动脉,制成病理切片进行HE染色及免疫组织化学染色,观察肾动脉内膜的变化和VEGF蛋白的表达,在电镜下观察动脉内膜的超微结构变化,以判断VEGF基因对犬肾动脉损伤后的作用。结果:肾动脉造影结果显示术后6周双侧肾动脉较术前均轻度狭窄,术后10周狭窄程度更明显,但治疗侧和对照侧之间狭窄程度差异无统计学意义;HE染色显示术后6周双侧肾动脉内膜较术前均轻度增生,10周时增生程度更明显,但治疗侧和对照侧肾动脉内膜增生程度均差异无统计学意义。免疫组织化学染色显示1周时,治疗侧肾动脉内膜及平滑肌的VEGF蛋白表达量明显高于对照侧,6周时仍有差异,但其差异减小;电镜显示:与对照侧比较,术后10周治疗侧动脉内膜覆盖较完全。结论:VEGF基因转染动脉壁后可以促进损伤动脉的内膜化,但不能阻止动脉内膜的过度增生及动脉损伤后形成的狭窄。     

缺氧与高胆固醇血症早期损害

高胆固醇血症(HC)损害从早期的内皮功能失调,发展到动脉粥样硬化经历了复杂的病理生理变化过程。HC早期存在的内皮功能失调、血流变学改变及血管炎症性损伤等可能引起缺氧,而缺氧通过直接损害和适应性反应促进缺氧诱导因子等相关基因转录、表达对机体产生复杂的反应和损害。HC损害发生的精确机制迄今仍未完全明确,尽管HC早期是否会引起缺氧以及缺氧与HC病理生理之间的关系尚待研究,但现有资料提示缺氧可能是引起HC损害的重要原因。     

Effect of Pentagastrin,Secretin, and Cholecystokinin on Gastric Secretion of Pepsin in Man

In eight volunteers the effect of pentagastrin (0.15, 1.0 and 6.0 μg/kg body weight/h), secretin (0.5 and 1.0 clinical units/kg b.w./h), and cholecystokinin (CCK) (0.5 and 1.0 Ivy dog units/kg b.w./h) on the gastric secretion of pepsin was investigated to ascertain whether interaction occurred. A high intraindividual variation was found, and also a significant washout of pepsin in the initial period after stimulation. Pepsin secretion was stimulated after pentagastrin (50% above basal level) and even more after secretin (75%-200% above basal level), whereas no stimulation but a tendency for depression was seen after CCK. With the doses of gastrointestinal hormones used in this investigation, no interaction between secretin and CCK on gastric secretion of pepsin in man was demonstrated.