三维培养的鼻粘膜腺体细胞中粘蛋白基因表达

粘液过量分泌是慢性呼吸道疾病的主要特征之一,慢性鼻窦炎的鼻粘液主要来源于鼻腔及鼻窦的粘膜下腺体细胞,而粘蛋白是鼻粘液的主要成分。目的:研究培养的鼻粘膜腺体细胞中粘蛋白基因的表达。方法:采用逆转录PCR(RT-PCR)技术,检测粘蛋白基因MUC2,MUC5AC,MUC5B的表达。结果:三维培养在Ⅰ型胶原蛋白凝胶内的人鼻粘膜腺体细胞(HNG)中,MUC2,MUC5AC和MUC5B均有表达,在培养液中加入大肠杆菌内毒素(LPS)8小时(100ng/ml)后,MUC2,MUC5AC表达明显增强,而MUC5B表达无变化。结论:实验结果提示,体外培养的HNG细胞可以作为探讨慢性呼吸道疾病粘液过量分泌的研究模型,LPS可以促进部分粘蛋白基因的表达。     

三维培养的鼻粘膜腺体细胞中粘蛋白基因表达

粘液过量分泌是慢性呼吸道疾病的主要特征之一，慢性鼻窦炎的鼻粘液主要来源于鼻腔及鼻窦的粘膜下腺体细胞，而粘蛋白是鼻粘液的主要成分。目的：研究培养的鼻粘膜腺体细胞中粘蛋白基因的表达。方法：采用逆转录PCR(RT-PCR)技术，检测粘蛋白基因MUC2，MUC5AC，MUC5B的表达。结果：三维培养在Ⅰ型胶原蛋白凝胶内的人鼻粘膜腺体细胞(HNG)中，MUC2，MUC5AC和MUC5B均有表达，在培养液中加入大肠杆菌内毒素(LPS)8小时(100ng／m1)后，MUC2，MUC5AC表达明显增强，而MUC5B表达无变化。结论：实验结果提示，体外培养的HNG细胞可以作为探讨慢性呼吸道疾病粘液过量分泌的研究模型，LPS可以促进部分粘蛋白基因的表达。     

白细胞介素-17A对鼻黏膜上皮细胞表达黏蛋白MUC5AC的刺激作用及分子机制

目的观察重组人白细胞介素17A(interleukin-1 7 A,I L-1 7 A)刺激离体培养的人鼻黏膜上皮细胞(human nasal epithelial cells,HNECs)后黏蛋白MUC5AC mRNA的表达变化,并检测相关的信号通路。方法离体培养的HNECs经过IL-17A诱导0～6 h后,通过定量聚合酶链反应(quantitative polymerase chainreaction,Q-PCR)技术检测MUC5AC mRNA的表达变化;通过Western blot技术检测有无特异性阻断剂作用时p38信号通路的活化情况及相应MUC5AC mRNA的表达情况。结果 IL-17A在1 ng/ml即能诱导HNECs中MUC5AC的mRNA水平上调,并在浓度为100 ng/ml时达到峰值(F=48.60,P<0.01);p38信号通路在IL-17A诱导后开始活化,并在第30分钟达到最大程度,之后信号递减并趋于正常;采用p38特异性阻断剂SB203580抑制p38信号通路后,MUC5AC mRNA的上调得到抑制(F=223.8,P<0.01)。结论 IL-17A能通过p38信号通路诱导HNECs表达MUC5AC mRNA的过程,阻断p38信号通路可能作为干预由IL-17A诱导导致的气道黏液高分泌状态的一个关键靶点。     

慢性鼻窦炎鼻窦黏膜中表皮生长因子及其受体的表达

目的 观察表皮生长因子受体(epidermal growth factor receptor,EGFR)及其配体表皮生长因子(epidermal growth factor,EGF)在慢性鼻窦炎患者鼻窦黏膜中的表达及分布,探讨EGFR信号通路与慢性鼻窦炎的关系.方法 取慢性鼻窦炎伴鼻息肉患者上颔窦窦口黏膜20例(Ⅰ型和Ⅱ型各10例),另以10例正常鼻窦黏膜作为对照,应用HE染色和免疫荧光技术观察EGF和EGFR在各组鼻窦黏膜中的表达,比较阳性细胞面积比在各组间的差异.结果 EGF和EGFR在Ⅰ型和Ⅱ型慢性鼻窦炎鼻窦黏膜中均有表达,其中EGF主要表达于上皮细胞,炎性细胞和部分黏膜下腺体亦有表达;而EGFR主要表达于杯状细胞,上皮细胞和基底细胞亦有表达,两组间阳性细胞面积比差异均无统计学意义(P＞0.05).正常鼻窦黏膜中上述部位仅有弱表达或无表达,阳性细胞面积比与两病变组差异均有统计学意义(P＜0.01).结论 EGFR及其配体EGF在慢性鼻窦炎伴鼻息肉患者鼻窦黏膜中均有明显表达,EGFR信号通路可能在慢性鼻窦炎的病理机制中发挥重要作用.     

白细胞介素-1β上调人鼻黏膜上皮细胞黏蛋白MUC2和MUC5B mRNA的表达

目的:探讨白细胞介素-1β(1L-1β)对鼻黏膜上皮细胞黏蛋白MUC2和MUC5B mRNA表达的影响.方法:在培养的第二代人鼻黏膜上皮细胞加入IL-1β(10μg/L)刺激24 h后,采用荧光定量RT-PCR检测人鼻黏膜上皮细胞中MUC2和MUC5B mRNA的定量表达.结果:在培养的鼻黏膜上皮细胞上均检测到MUC2和MUC5B mRNA的表达,IL-1β刺激组MUC2 mRNA定量表达[(39.26±6.10)×104拷贝/μg]高于对照组[(5.70±4.16)×104拷贝/μg],差异有统计学意义(P<0.01);IL-1β刺激组MUC5BmRNA定量表达[(5.72±2.06)×105拷贝/μg]高于对照组[(1.11±0.72)×10.拷贝/μg],差异有统计学意义(P<0.05).结论:在培养的鼻黏膜上皮细胞中IL-1β组的MUC2和MUCSB mRNA表达均高于对照组,提示IL-1β可能具有上调鼻黏膜上皮细胞黏蛋白mRNA的表达作用.     

豚鼠实验性变应性鼻炎最轻持续炎性反应模型的建立

目的 建立豚鼠实验性变应性鼻炎最轻持续炎性反应(minimal persistent inflammation,MPI)模型,并初步探讨其病理机制及意义.方法 60只健康雄性Hartley系豚鼠,随机分为A～D共4组,每组15只.A组为阳性对照组,B组为实验组即MPI组,C组为阴性对照组,D组为空白对照组.首先以含卵清蛋白和氢氧化铝凝胶的生理盐水混合液对A、B、C 3组行基础致敏和强化致敏,再分别用1%和0.01%的卵清蛋白溶液或生理盐水长期鼻腔激发.D组始终以生理盐水进行致敏和激发.观察豚鼠鼻腔激发后症状(喷嚏)变化并检测鼻黏膜中嗜酸粒细胞(eosinophils,EOS)浸润程度及上皮细胞内细胞间黏附分子1(intercellular adhesion molecule 1,ICAM-1)的表达情况.结果 MPI模型组在以l%卵清蛋白溶液激发时,喷嚏平均次数明显多于D组(P<0.05),而与A、C组相比差异无统计学意义(P值均>O.05);改用0.01%卵清蛋白溶液鼻腔激发后,变应性鼻炎症状基本消失,与D组相比差异无统计学意义(P>0.05),但鼻黏膜内仍有少量EOS浸润,EOS计数明显多于D组(P相似文献   

白细胞介素13在嗜酸粒细胞性慢性鼻-鼻窦炎合并鼻息肉组织中的表达及其与黏蛋白高分泌的相关性研究

目的 明确白细胞介素13(IL-13)在嗜酸粒细胞性慢性鼻-鼻窦炎(eosinophilic chronic rhinosinusitis with nasal polyps,EOS-CRSwNP)中的表达,探讨在EOS-CRSwNP中IL-13和黏蛋白5AC(mucin 5AC,MUC5AC)的相关性.方法 利用免疫组化和ELISA方法观察和测量MUC5AC在对照组鼻黏膜组织和EOS-CRSwNP组织的表达,ELISA法检测IL-13在对照组鼻黏膜组织和EOS-CRSwNP组织的表达;双变量相关性分析研究EOS-CRSwNP中IL-13和MUC5AC的相关性.IL-13与原代培养鼻黏膜上皮细胞共孵育,ELISA检测细胞上清中MUC5AC的表达.结果 免疫组化染色见MUC5AC主要表达在鼻黏膜上皮,通过ELISA检测,EOS-CRSwNP中MUC5AC和IL-13均较对照组显著升高.双变量相关性分析表明在EOS-CRSwNP中MUC5AC与IL-13存在高度相关,进一步通过IL-13与气液界面原代培养人鼻黏膜上皮细胞共孵育,MUC5AC分泌显著增加.结论 MUC5AC和IL-13在EOS-CRSwNP中表达升高,MUC5AC的高分泌与IL-13高表达密切相关.     

鼻腔吸入γ干扰素对大鼠变应性鼻炎的治疗作用

目的 探讨鼻腔吸入γ干扰素(interferon gamma,IFN-γ)对大鼠变应性鼻炎(allergic rhinitis,AR)的治疗作用及可能机制.方法 采用卵白蛋白、氢氧化铝建立大鼠AR模型,分为阳性对照组(B组)、IFN-γ组(c组)和丙酸倍氯米松组(D组),每组8只大鼠,分别于模型建立后第31～38天,每只每日每侧鼻腔滴入磷酸盐缓冲液50μl、IFN-γ1 μg和丙酸倍氯米松3.5 μg,另设阴性对照组(A组)大鼠8只.第39天取鼻腔灌洗液测定细胞成分、白细胞介素4和白细胞介素5浓度;取血测定血浆IgE水平;黏膜切片观察鼻腔组织病理学改变及GATA-3的表达.结果 C组鼻腔灌洗液中的嗜酸粒细胞数量(-x±s,下同)为(O.005±0.003)×104/ml,明显低于B组(0.225±0.060)x104/ml(P<0.01);C组鼻腔灌洗液中的白细胞介素4为(7.8±3.5)pg/ml,白细胞介素5为(12.5±4.3)pg/ml,均低于B组(P值均<0.01);C组血浆中总IgE为(38.5±9.6)μg/ml,卵白蛋白特异性IgE为(19.8±5.4)IU/ml,均低于B组(P值均<0.01).B组大鼠鼻腔黏膜充血、水肿,黏膜层增厚,并有嗜酸细胞为主的炎性细胞浸润,而c组大鼠上述炎性症状改变减轻.免疫组化显示B组鼻腔组织中GATA-3表达增加,而C组的表达减少.结论 鼻腔吸入IFN-γ可以抑制AR大鼠白细胞介素4和白细胞介素5的合成,抑制嗜酸粒细胞在鼻腔内的炎性浸润,降低血浆中总IgE和卵白蛋白特异性IgE水平,其机制可能与阻断GATA-3表达,从而继发抑制Th2型反应有关.     

杀菌-通透性增强蛋白对分泌性中耳炎大鼠水通道蛋白和黏蛋白表达的影响

目的观察杀菌-通透性增强蛋白对分泌性中耳炎模型大鼠中耳黏膜中水通道蛋白和黏蛋白表达的影响,探讨可能的作用机制。方法采用内毒素制备分泌性中耳炎大鼠模型,将70只大鼠随机分为模型组(10只)和杀菌-通透性增强蛋白(bactericidal-permeability increasing protein,BPI)组(60只),另取10只大鼠作为正常对照组,采用ELISA法检测给药后各组大鼠中耳积液中水通道蛋白AQP1、AQP4及黏蛋白MUC5B、MUC5AC水平,实时荧光定量PCR法检测各组大鼠中耳黏膜中AQP1、AQP4及MUC5B、MUC5AC mRNA的表达水平。结果模型组AQP1蛋白及mRNA表达量显著低于正常对照组,而AQP4、MUC5B、MUC5AC蛋白及mRNA表达量显著高于正常对照组(P<0.01)。经BPI治疗后,AQP1的表达升高,而AQP4、MUC5B、MUC5AC的表达降低(P<0.05或0.01)。结论 AQP1、AQP4及MUC5B、MUC5AC在分泌性中耳炎病变的形成中起一定作用;BPI通过提高AQP1,抑制AQP4及MUC5B、MUC5AC的表达和分泌,从而减轻分泌性中耳炎的积液分泌;BPI是一个潜在的治疗分泌性中耳炎的药物,可能有效预防慢性分泌性中耳炎的发生。     

白介素-17A和MUC5AC在变应性鼻炎患者鼻黏膜中的表达及相互关系

目的 探讨变应性鼻炎患者鼻黏膜中白介素(interleukin,IL) -17A及黏蛋白MUC5AC的表达及相互关系.方法 总共纳入14例中-重度持续性变应性鼻炎患者和9例正常对照者,采用定量逆转录聚合酶链反应(qRT-PCR)和免疫组化检测下鼻甲黏膜中IL-17A和MUC5AC的mRNA及蛋白表达情况,评估两者之间的关联性.结果 变应性鼻炎患者鼻黏膜中IL-17A和MUC5AC mRNA表达分别比对照组织上升3.7倍和8.9倍,差异有统计学意义(P＜0.01),两者的蛋白表达强度也显著高于正常对照组(p＜0.05).而且IL-17A和MUC5AC的mRNA与蛋白表达之间存在显著正相关(r=0.79和r=0.85,P＜0.05).结论 IL-17A可能通过刺激MUC5AC的表达加重变应性鼻炎的临床严重度并且影响其疗效.     

表皮生长因子与其受体在鼻息肉上皮中的表达

目的 探讨表皮生长因子(EGF)及其受体(EGFR)在鼻息肉上皮中的表达及其意义。方法 收集鼻息肉标本25例, 正常下鼻甲黏膜组织10例, 采用免疫组化及实时荧光定量PCR技术, 观察EGF与EGFR在鼻息肉和正常下鼻甲黏膜组织中的表达情况。结果 与正常下鼻甲黏膜组织相比, EGF及EGFR的mRNA水平在鼻息肉组织中的表达下降。在免疫组化染色中, EGF及EGFR主要表达在上皮的基底层细胞, 而且在鼻息肉中的表达下降。结论 EGF及EGFR在正常鼻黏膜组织上皮的发生与修复中有着重要的作用。EGF及EGFR在鼻息肉中蛋白水平与mRNA水平表达的下降表明在鼻息肉中上皮修复功能的下调或缺失可能导致或促进鼻息肉的发生。     

hEGF、TGFβ2对兔角膜内皮细胞损伤的作用及相关蛋白 p27Kip1和 Cdk4 的表达

目的：观察人表皮生长因子（hEGF）、转化生长因子β2（TGFβ2）对家兔角膜内皮细胞损伤的作用及相关蛋白 p27Kip1和Cdk4的表达。方法：体外培养家兔角膜内皮细胞传一代融合后，定量损伤直径3.5?mm范围内的细胞，培养液中分别加入不同浓度的hEGF和（或）浓度为10?ng/ml的TGFβ2，对照组不加任何药物。损伤后第1、3、5，7天倒置显微镜下照相并用计算机测量未愈合面积。应用免疫荧光染色法，检测损伤修复不同阶段p27Kip1和Cdk4的含量。结果：一定质量浓度的hEGF可加快体外培养的家兔角膜内皮细胞的损伤愈合并上调Cdk4的表达, 且具有剂量依存性，以10～40?ng/ml为最适宜。外源性TGFβ2抑制角膜内皮细胞损伤修复。hEGF孵育损伤模型24?h后，TGFβ2对此无抑制作用。 TGFβ2作用损伤模型24?h后，可抑制hEGF的促修复作用。结论：一定质量浓度的hEGF能促进体外培养的家兔角膜内皮细胞的损伤修复并上调Cdk4的表达。外源性TGFβ2可抑制家兔角膜内皮细胞的损伤修复并上调p27Kip1的表达。     

表皮生长因子及地塞米松对爆震性聋治疗作用的实验研究

为研究爆震后豚鼠耳蜗毛细胞表皮生长因子受体（epidermalgrowthfactorreceptor，EGFR）的表达，以及表皮生长因子（epidermalgrowthfactor，EGF）及地塞米松（dexamethasone，DXM）的治疗效果，采用免疫组织化学ABC技术和听性脑干反应（ABR）检测。结果发现正常豚鼠耳蜗内、外毛细胞有散在的表皮生长因子受体（EGFR）表达，阳性反应位于听毛，呈节段性分布。爆震后24小时EGFR阳性反应分布于内毛细胞胞浆。爆震后72小时内毛细胞听毛和外毛细胞皮板呈阳性反应。震后1周内毛细胞阳性反应明显增多，部分外毛细胞听毛呈阳性反应。EGFR阳性反应至2周有所减少。震后1个月内、外毛细胞听毛均呈EGFR阳性反应。EGF及DXM对爆震性聋均有一定的治疗作用，二者合用可使豚鼠听力明显恢复。结果提示，毛细胞损伤修复可能与EGF有关。     

IL-17C expression in nasal epithelial cells of chronic rhinosinusitis with nasal polyposis

Interleukin 17C (IL-17C) is a functionally distinct member of the IL-17 family that is selectively induced in epithelia by bacterial challenge and inflammatory stimuli. The goal of this study was to explore the expression of IL-17C in nasal epithelial cells and their role in the pathogenesis of chronic rhinosinusitis with nasal polyposis (CRSwNPs). IL-17C expression was detected using immunohistochemistry (IHC) of the epithelial cell layers and using the western blot assay on whole tissue homogenates from control subjects (n = 10) and CRSwNP patients [10 non-eosinophilic polyps and 10 eosinophilic polyps (EPs)]. Expression of IL-17C and P47-phox were evaluated in the human nasal epithelial cells (RPMI-2650 cells) after treatment with staphylococcal enterotoxin B (SEB) and pretreatment with reactive oxygen species (ROS) scavenger, N-acetyl l-cysteine (NAC). Finally, IL-17C expression was demonstrated in eosinophilic rhinosinusitis murine model using IHC. Epithelial expression of IL-17C was higher in nasal polyps (especially in EPs) compared to control mucosa. SEB increased the expression of IL-17C and P47-phox in RPMI-2650 cells. SEB-induced expressions of both IL-17C and P47-phox were significantly decreased in NAC-pretreated cells. Epithelial expression of IL-17C was significantly higher in experimental mice compared to control mice. SEB-induced IL-17C expression in nasal epithelial cells is mediated by ROS production. This pathway may be associated with the pathogenesis of CRSwNP, especially eosinophilic nasal polyps.     

鼻内翻性乳头状瘤中表皮生长因子及受体的表达与恶变的关系

目的探讨表皮生长因子(EGF)及其受体(EGFR)在鼻内翻性乳头状瘤(NIP)恶变前不同阶段中的表达情况及其生物学意义.方法应用免疫组织化学LSAB法检测NIP非典型增生的不同阶段及恶变组织中EGF、EGFR的表达情况.应用图像分析仪对染色结果进行定量分析.结果在上皮组织和间质结缔组织中EGF、EGFR阳性染色随着不典型增生程度的加重,其表达强度和范围也增加.中-重度不典型增生组织的表达强度与鳞状细胞癌组织接近.轻度不典型增生与NIP比较,中-重度不典型增生与轻度比较,EGF、EGFR表达差异均有统计学意义(均P<0.01).结论EGF参与了NIP的病理过程,EGF、EGFR的表达随肿瘤异型程度的增加而强度增加,其表达水平可以作为衡量NIP恶变倾向的指标之一.     

The effect of endotoxin and prostaglandin E2 on the proliferation of keratinocytes in vitro

Since the rate of epidermal basal cell proliferation appears to be a crucial factor in the development of acquired cholesteatoma, we studied the effect of prostaglandin E2 (PGE2) and endotoxin on the growth of keratinocytes. PGE2 and endotoxins are inflammatory mediators in chronic otitis media. Various concentrations of endotoxin and PGE2 were added to keratinocytes derived from newborn rats. The synthesis of DNA was then studied by incorporation of 3H-thymidine into the keratinocytes. We found that either endotoxin or PGE2 alone inhibited DNA synthesis by keratinocytes, while endotoxin (10 micrograms/ml) and PGE2 (10 ng/ml) together stimulated DNA synthesis by keratinocytes. These findings suggest that inflammatory mediators, such as endotoxin plus PGE2, in chronic otitis media stimulate the growth of epidermal basal cells of cholesteatoma.     

Increased expression of epidermal growth factor receptors in the tracheal epithelia after topical mitomycin-C in rabbits

The aim is to examine histopathological changes and expression of epidermal growth factor receptor (EGFR) in tracheal epithelia caused by application of topical mitomycin-C (MMC) in rabbit model after the tracheotomy procedure. The conventional tracheotomy was performed in 16 rabbits. They were randomly divided into two equal groups. The first group was applied MMC at a concentration of 0.4 mg/ml around tracheotomy for 5 min, and the other group was not taken a treatment as a control. The animals were sacrificed at the end of 4 weeks. Their tracheas were evaluated with H&E and Masson's trichrome histochemically, and with antiepidermal growth factor receptor immunohistochemically. Results showed that there was no significant difference between MMC and control group for inflammatory cells (P=0.09). The numbers of fibroblasts and subepithelial tissue thickness in the group exposed to MMC were significantly lower than the control group (P<0.05). In contrast, the percentage of EGFR in the application of MMC group was significantly higher than the control group (P<0.05). The application of topical MMC on airway epithelia after tracheotomy showed significant elevation in the levels of epithelial EGFR expression compared to controls in a rabbit model. The activation of epithelial EGFR may facilitate epithelial healing, but further studies are needed to assess the effect of topical MMC on respiratory epithelia.     

ErbB and Nrg: potential molecular targets for vestibular schwannoma pharmacotherapy.

OBJECTIVE: Identify molecular targets for development of tumor-specific pharmacotherapeutics aimed at treating vestibular schwannomas (VSs). Activated epidermal growth factor receptor B (ErbB) 2 and ErbB3 are abundantly expressed in VS. ErbB2 signaling is essential for Schwann cell differentiation, survival, and proliferation. VS arise after loss of functional merlin, a putative tumor suppressor. Merlin internalizes ErbB2 receptors in rodent Schwann cells.Unregulated ErbB signaling may contribute to VS tumorigenesis. STUDY DESIGN: Molecular analyses, retrospective clinical correlation. SETTING: Tertiary referral center. PATIENTS: Thirty-eight specimens from patients operated for sporadic (n=21) and neurofibromatosis (NF) 2-related (n=17) VS. INTERVENTION(S): VS analyses via real-time polymerase chain reaction, immunohistochemistry, and correlation with patient clinical data. MAIN OUTCOME MEASURE(S): ErbB signaling molecule expression, tumor size, age, and NF2 status. RESULTS: VS upregulated epidermal growth factor (EGF) receptor in 68% (62% sporadic and 75% NF2-associated VS) and ErbB2 in 84% (76% sporadic and 94% NF2-related VS). ErbB3 was upregulated in 34%, and ErbB4 is downregulated in NF2-related VS. Of EGF receptor (EGFR) ligands, EGF was upregulated in all NF2-related VS, but none of the sporadic VS (p<0.01), and transforming growth factor alpha and beta-cellulin showed upregulation in 67% of NF2-related VS but not sporadic VS (p=0.02 and p=0.01, respectively). Neuregulin (Nrg) was upregulated in 86% of sporadic VS versus 19% of NF2-related VS (p<0.01). EGFR expression levels correlated directly with VS tumor size and inversely with patient age, whereas Nrg expression correlated directly with age (p=0.0005). EGF expression predicts NF2 status, whereas Nrg predicts non-NF2 status (p<0.01). CONCLUSION: These findings implicate the ErbB pathway in VS growth and as potential molecular targets for VS pharmacotherapy.     

表皮生长因子及其受体在中耳慢性鼓膜穿孔病变中的作用

OBJECTIVE: To evaluate the possible roles of epidermal growth factor(EGF) and its receptor (EGFR) on the chronic tympanic membrane perforations. METHODS: A phosphate buffer saline of EGFR was administered to a Gelfoam pledget placed over chronic tympanic membrane perforations in guinea pigs. The EGFR of 10 specimens from the acquired middle ear cholesteatoma of the adjacent skin around perforation was examined by immunohistochemical SP method and computer image analysis. Results Complete closure of the tympanic membrane perforations was observed in 82.6% of EGF-treated ears, but only 33.3% in the controls(P < 0. 01). No case was led to middle ear cholesteatoma in the experiment group (0/23). The positive expression in the adjacent skin around perforation was (39.3 -/+ 7.4)%; and the normal external ear skin was (25.4 +/- 3.7)%; There were distinctly significant differences between the adjacent skin around perforation and the normal external ear skin (P < 0. 01). CONCLUSIONS: EGF is effective on closing chronic tympanic membrane perforations in the guinea pigs. Present data suggests that EGF-treated may induce the occurrence of middle ear cholesteatoma.