不同乳中表皮生长因子含量的测定

乳中不仅含有丰富的营养物质,也含有免疫球蛋白、酶、激素、生长因子等多种生物活性物质,对新生的哺乳动物的健康成长和发育起着重要的作用.其中,乳源性生长因子是一类存在于乳中的多肽类生长因子,它们是细胞因子的一种,通过与靶细胞表面的相应受体结合发挥其生物学效应,从而对细胞的生长、分化及功能产生一定的影响.初乳中的表皮生长因子(epidermal growth factor,EGF)是人类和其他哺乳动物母乳的重要成分之一.     

瘤胃上皮细胞增殖和物质转运分子机制的研究进展

瘤胃作为反刍动物特有的消化器官,对饲粮营养消化利用具有重要作用。近50年来,人们对瘤胃上皮细胞发育和物质转运做了大量研究,重点聚焦于瘤胃上皮细胞增殖分子机制及相关转运蛋白调控通路的探索,如胰岛素样生长因子(IGF)和表皮生长因子(EGF)参与调控葡萄糖的转运,钠氢交换蛋白(NHE)、单羧酸转运载体(MCTs)和G蛋白偶联受体(GPR)参与瘤胃上皮细胞短链脂肪酸(SCFA)的转运等。尽管如此,我们对于瘤胃发育的内在机制了解非常有限,本文针对反刍动物瘤胃上皮细胞增殖和物质转运分子机制的研究进展进行了综述,对于进一步理解瘤胃上皮细胞发育过程及建立最佳的反刍动物营养供给策略具有重要意义。     

表皮生长因子

早在1959年，Cohen纯化神经生长因子时，发现小鼠颌下晚中存在一种可刺激神经细胞生长的活性物质”’．1962年作者对其进行分离提取，并将其命名为表皮生长因子（EpidermalGr。thPactor，EGF）’‘’。EGF是生物学效应相当广泛的一种生长因子，民肽类激素，能刺激体内或体外培养的多种组织和细胞类型的有丝分裂、增殖或分化。近年来，在人类医学上，国内外学者对EGF的研究日益增多，使其成为迄今为止唯一达到临床应用水平的生长因子。”’在畜牧业上，国外学者应用其进行绵羊脱毛，促进家寄生长和伤口愈合的实验取得了一定进展’”，…     

EGF基因在动物方面的研究进展

EGF(Epidermal growth factor)是一组具有和表皮生长因子较高同源结构的糖蛋白,与其相似的生物学功能糖蛋白也属于EGF受体的配体。近年来。许多学者对EGF基因的研究发现,它们都具有胚胎细胞生长功能的调节作用。本文总结了EGF家族的生物学特性,EGF的结构和生物学作用以及其他EGF家族成员的研究概况,以期为日后对EGF基因的研究提供参考。     

牛初乳的研究进展

近年来,随着物理学、生物化学、医学和分子生物学等学科的发展,研究发现牛初乳中不仅含有丰富的营养物质,而且还含有大量的十分珍贵的非营养性功能组分--抗菌因子和生长因子,它们具有改善胃肠道功能、增进免疫调节、延缓衰老、促进细胞生长发育和加速伤口愈合等多种功能.疗药品的发展趋势介绍如下.     

钠葡萄糖共转运载体(SGLT1)研究进展

综述了钠葡萄糖共转运载体(SGLT1)研究的新进展，葡萄糖的跨膜转运主要是通过SGLT1结合1mol葡萄糖，2mol的Na^ ，形成Na^ -载体-葡萄糖复合物，顺Na^ 的浓度梯度进入细胞。不同物种的SGLTl具有较高的同源性，大小为662～665个氨基酸。其二级结构业已阐明，它由14个连为一体的α螺旋(MS1～MS14)组成，动物种类、年龄、饥饿状况、Na^ 摄入水平和血清醛固酮水平均影响SGLT1的基因表达，表皮生长因子(EGF)、精氨酸加压素(AVT)、胰岛素样生长因子(IGF)以及蛋白激酶A和蛋白激酶C对SGLT1的表达具有调节作用。     

细胞因子对牛乳腺上皮细胞体外增殖作用评价

分离纯化了乳腺上皮细胞,对细胞进行角蛋白免疫组化鉴定后,比较不同细胞因子对乳腺上皮细胞生长的影响.结果显示,生长因子EGF或HGF对牛乳腺上皮细胞的增殖具有重要作用,17β-E2不能促进牛乳腺上皮细胞的增殖,但可与EGF协同促进牛乳腺上皮细胞的增殖,表明17β3-E2对EGF诱导的乳腺上皮细胞增殖具有重要作用.     

肠道葡萄糖吸收的调节作用

肠道葡萄糖是经过肠粘膜上皮细胞上的Na+-依赖葡萄糖同向转移器 ( SGLI1)而吸收的。借助于基底膜上 Na+/K+ATP酶维持的电化学梯度驱动 ,胃肠道将消耗整个能量的 2 0 % ,其中的大多数是由于 Na+/K+酶作用的结果。肠道葡萄糖的主动转运受大量胃肠肽的调节 ,如表皮生长因子 ( EGF)和肽 YY( PYY)。 EGF和 PYY可将肠道葡萄糖吸收提高 2 0 0 %～ 30 0 % ,值得一提的是肠道组织功能的能耗的改变与转运的葡萄糖量相关 ,这个值定义为“葡萄糖吸收的表观能效率( APEE)”,用于评价各种生理和营养状态下葡萄糖和其它营养物质的能耗值。很少…     

EGF基因在动物卵泡发育过程中的研究进展

表皮生长因子(EGF)是表皮上生长家族的重要调节因子之一,可促进细胞增殖分化、调控细胞的衰老以及诱导肿瘤的发生。在动物卵巢卵泡的研究中发现,EGF可以有效地抑制卵泡细胞的凋亡、促进颗粒细胞的增殖和卵母细胞的成熟,因此近年来受到了越来越多的学者的关注。为了进一步认识EGF基因对各级卵泡的调节作用,文章拟从EGF基因的结构、对卵泡发育的作用机理等角度进行阐述,为研究EGF基因参与调控动物卵泡发育过程的作用机制提供参考。     

甲状腺素、胰高血糖素和表皮生长因子对肉鸡小肠Ⅰ型肽转运载体mRNA表达量的影响

本试旨在研究甲状腺素、胰高血糖素(PG)和表皮生长因子(EGF)对肉鸡小肠Ⅰ型肽转运载体(PepTl)mRNA表达量的影响.选择体重无差异的25日龄雄性肉仔鸡30只,分为5组,每组6只鸡,分别接受不同激素处理,每天1次,连续5 d.对照组、EGF组、PG组分别皮下注射蒸馏水0.20 mL/kg、EGF 0.03 mg/...     

Expression of tumor necrosis factor-alpha and cyclooxygenase-2 mRNA in porcine split-thickness wounds treated with epidermal growth factor by quantitative real-time PCR

Epidermal growth factor (EGF) accelerates the re-epithelialization of damaged epidermal cell layers in a wound, so it especially shortens the duration of wound healing. The effect of EGF on pro-inflammatory cytokines, tumor necrosis factor-alpha (TNF-alpha) and cyclooxygenase-2 (COX-2), levels during wound healing has not been reported. We investigated the relationship between exogenous EGF treatment and the expression of TNF-alpha and COX-2 mRNA in porcine split-thickness wounds by real-time PCR. Twenty split-thickness wounds were created on the back of five pigs. Fifteen wounds were treated twice daily with EGF ointments (1 microg/g, 10 microg/g, and 50 microg/g) for 10 days and five wounds were untreated. Healing time until full-epithelialization was evaluated. We performed a quantitative analysis of TNF-alpha and COX-2 mRNA expression in wound biopsies using real-time PCR. Topical application of 1 microg/g EGF accelerated re-epithelialization more than treatments of EGF at 10 microg/g and 50 microg/g, and no treatment. The levels of TNF-alpha and COX-2 mRNA were significantly greater in wounds treated with 1 microg/g than those with 10 microg/g and 50 microg/g EGF, and no treatment. Topical treatment of EGF influences the level of TNF-alpha and COX-2 mRNA within porcine split-thickness wounds. EGF-dependent slightly up-regulation of TNF-alpha and COX-2 mRNA expression during the inflammatory phase of healing may create an optimal molecular environment for wound healing.     

Effects of epidermal growth factor on placental amino acids uptake in pregnant rats

To evaluate the effects of epidermal growth factor (EGF) on placental amino acids uptake, transport activities for L-proline, L-leucine, and L-alanine were kinetically examined in placental microvillous vesicles(PMV) obtained from pregnant rats administered with EGF(100 and 200 microg/kg/day) from day 18 to 21 of pregnancy. The Vmax of Na(+)-dependent proline uptake remarkably increased with a dose-dependent manner of EGF, while Km did not change. In contrast, Vmax and Km values of Na(+)-dependent and -independent alanine, and Na(+)-independent leucine uptake were not affected. These results suggested that EGF enhanced proline transport activity in placental microvillous membranes, resulting in an increase of proline concentration in the fetal blood. The selective up-regulation of proline uptake was considered to contribute to fetal growth by EGF.     

Effect of topical administration of epidermal growth factor on healing of corneal epithelial defects in horses

OBJECTIVE-To characterize healing of corneal epithelial defects in horses and to evaluate the ability of epidermal growth factor (EGF) to modulate rate of corneal epithelial healing in horses. SAMPLE POPULATION: 20 eyes in 12 adult horses. PROCEDURE: Corneal epithelial wounds were created by mechanically debriding the limbus. Corneal healing was recorded for 3 treatment groups: 50 microg of EGF/ml (n = 5 eyes), 5 microg of EGF/ml (7), and PBS solution (8). Corneal healing was recorded once daily after instillation of fluorescein stain by use of photography and calculating the area of the wound, using imaging software. RESULTS: After corneal debridement, re-epithelialization was rapid and progressed in a linear fashion for the first 5 to 7 days after surgery in all groups. After that period, rates of healing decreased. A profound increase in the degree of inflammation, neovascularization, melanosis, and scarring was observed in eyes treated with the high dose of EGF (50 microg/ml), but there was not a statistical difference in mean healing time or in mean decrease in radius during the linear phase between the control and either EGF treatment groups. However, for all 8 horses in which both eyes were debrided, the first eye healed significantly faster than the second eye, regardless of treatment. CONCLUSIONS AND CLINICAL RELEVANCE: Beneficial effects of topical administration of a high dose of EGF for acceleration of healing of corneal defects in eyes of horses are outweighed by the intensity of the associated inflammatory response.     

Effects of EGF receptor ligands on fetal ovine myoblasts

Epidermal growth factor (EGF) receptors are widely distributed in mammalian tissues, including muscle. One ligand of these receptors, heparin-binding epidermal growth factor-like growth factor (HB-EGF) is also strongly expressed in adult muscle. However, in vitro studies of EGF action in cultured muscle cells of different species have yielded conflicting results. The purpose of this study was to investigate the potential role of EGF and related factors in the growth and development of fetal ovine muscle. High affinity EGF receptors were detected on clonally purified ovine fetal myoblasts, using [(125)I] human EGF as a ligand (K(d) values of 47 and 54 pM in separate experiments). Competitive binding studies in mixed secondary cultures showed that EGF had the highest affinity for the fetal ovine receptor, followed by HB-EGF and transforming growth factor alpha (TGF-alpha). These ligands all stimulated DNA synthesis in clonally purified ovine myoblasts, with their relative potencies at 0.1 nM reflecting their receptor binding affinities. Maximal effects were seen at 1-10 nM. EGF (10 nM) did not significantly inhibit the differentiation of clonally purified fetal ovine myoblasts, although there was increased proliferation of nondifferentiating cells. Hence a variety of EGF receptor ligands have the potential to influence the proliferation ovine muscle cell precursors in utero, but it is unlikely that they promote differentiation.     

表皮生长因子对成年水牛晶状体上皮细胞促增殖作用

为观察表皮生长因子 ( epidermalgrowth factor,EGF)对成年水牛晶状体上皮细胞增殖作用的影响。将不同浓度 EGF作用于体外培养的成年水牛晶状体上皮细胞 ,采用 MTT法测定细胞的增殖能力。结果 :EGF在浓度为 1ng/ m L和 1 0 ng/ m L作用的前 3 d促增殖作用逐渐加强 ,呈现时间依赖性 ,且在第 3 d达到最大促增殖效果。不同浓度的 EGF对晶状体上皮细胞的增殖作用不同 ,浓度在 1 0 ng/ m L作用 2 4h后即有明显的促增殖作用 ( P <0 .0 5) ,而作用72 h后最低的有效浓度为 1 ng/ m L,而且 2 50ng/ m L EGF有最大促增殖作用。结论 :EGF是诱导成年水牛晶状体上皮细胞增殖的重要因素。     

促卵泡素和表皮生长因子对鸡胚精原细胞增殖的作用

利用精原细胞-体细胞体外无血清共培养模型研究了促卵泡素(FSH)和表皮生长因子(EGF)对鸡胚精原细胞增殖的作用。结果表明:单独的FSH(10～100ng/mL)或EGF(10～100ng/mL)可显著增加精原细胞的数目以及增殖细胞核抗原的表达。EGF(10ng/mL)联合FSH(10ng/mL)具有加性效应,但更高剂量的EGF(100ng/mL)则降低了FSH的促进作用。因此,FSH联合适量的EGF可促进精原细胞的增殖。     

Effects of dietary supplementation with epidermal growth factor on nutrient digestibility,intestinal development and expression of nutrient transporters in early‐weaned piglets

The abnormalities in intestinal morphology and digestive function during weaning are associated with the loss of milk‐borne growth factors. Epidermal growth factor (EGF) has been shown to stimulate the growth of animals. This study was to determine the effect of dietary EGF on nutrient digestibility, intestinal development and the expression of genes encoding nutrient transporters in weaned piglets. Forty‐two piglets were weaned at 21 days and assigned to one of three treatment groups: (1) basal diet (control), (2) basal diet + 200 µg/kg EGF or (3) basal diet + 400 µg/kg EGF. Each treatment consisted of 14 replicates, and seven piglets from each treatment were sampled on day 7 and 14. The EGF supplementation significantly elevated (p < 0.05) the coefficients of total tract apparent digestibility of crude protein, calcium and phosphorus, but tended to decrease sucrase activity (p < 0.10) than the control group. At day 7 post‐weaning, animals receiving EGF diets showed a tendency (p < 0.10) towards greater ileal villus height (VH), jejunal crypt depth (CD) and duodenal VH:CD when compared with the control group. Moreover, the mRNA levels of glucose transporter 2 (Slc2a2), neutral amino acid transporter (Slc6a19) and calbindin D9k (S100G) tended to be higher (p < 0.10) for EGF groups than the control group. By day 14, EGF supplementation markedly enhanced (p < 0.05) the VH, CD and VH:CD in the jejunum compared to the control group. This addition also up‐regulated (p < 0.05) the mRNA level and the protein abundance of peptide transporter 1 than the control group. These findings demonstrated that dietary EGF beneficially enhanced nutrient digestibility, improved intestinal development and increased the mRNA expression of nutrient transporters in weaned piglets.     

生长因子EGF、bFGF对猪孤雌胚体外发育的影响

在胚胎发育的不同阶段，分别在培养基中添加EGF和bFGF，研究EGF和bFGF对猪孤雌胚体外发育的作用。结果表明：在1细胞阶段添加EGF或bFGF，添加EGF能够显著提高孤雌胚的卵裂率（P〈0．05）；2～4细胞阶段添加EGF和bFGF，添加EGF组和添加bFGF组的囊胚率都显著高于对照组（P〈0．05），而添加bFGF组的囊胚率和囊胚细胞数都略高于对照组和添加EGF组。说明EGF和bFGF有利于猪孤雌胚的体外发育，而且，bF-GF能够通过提高囊胚细胞数而提高猪孤雌胚的质量。     

EGF和FGF-2对猪皮下脂肪神经嵴干细胞增殖和分化的影响

【目的】探究表皮生长因子（epidermal growth factor，EGF）和成纤维细胞生长因子2（fibroblast growth factor 2，FGF-2）对猪皮下脂肪神经嵴干细胞（neural crest stem cells，NCSCs）增殖及分化的影响，以优化猪皮下脂肪神经嵴干细胞的培养条件。【方法】通过体外分离培养原代猪皮下脂肪NCSCs，免疫荧光染色鉴定NCSCs标志物p75 NTR，并用不同浓度的EGF和FGF-2（0和0、10和10、10和20、20和10、20和20、30和30 ng/mL）作用于传代猪皮下脂肪NCSCs，用CCK-8试剂盒测定细胞增殖率，确定细胞生长的最适EGF和FGF-2浓度，将试验分为空白组和最适浓度组，测定两组细胞的生长曲线，成脂化诱导后油红O染色，对比两组细胞的脂滴生成量。【结果】免疫荧光染色结果显示，原代猪皮下脂肪NCSCs经p75 NTR鉴定呈阳性。CCK-8细胞增殖试验结果显示，EGF和FGF-2的浓度均为20 ng/mL时对传代猪皮下脂肪NCSCs的促增殖作用最佳。生长曲线显示，两组细胞均在第5~9天处于对数生长期，第10~15天细胞增殖减缓，逐渐到达停滞期。油红O染色结果显示，最适浓度组胞质内的脂滴生成量远多于对照组。【结论】在培养液中添加20 ng/mL EGF和20 ng/mL FGF-2对猪皮下脂肪NCSCs的增殖和分化有促进作用。