enng and Esophageal-Neoplasms

In order to establish an effective method to induce selectively experimental dog esophageal carcinoma, we compared the restricted oral administration of N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) with projecting spout with the ad libitum oral administration of it. Five dogs were given a solution of ENNG at a concentration of 50mg/l with restricted oral administration with projecting spout for 52 weeks. In all of them, elevated type of esophageal lesions were endoscopically observed soon after the cessation of the ENNG administration. Histological examination revealed that besides the multiple squamous cell carcinomas of the esophagus, various degrees of dysplasias were seen. Two dogs had metastasizes to the regional lymph nodes and one dog had metastatic lesions in the lung. Gastric carcinomas were also seen in four dogs. Another five dogs were given ad libitum the same concentration of ENNG solution. Gastric carcinomas were induced in four dogs, but esophageal carcinomas were seen in small lesions in two dogs. The restricted oral administration of ENNG with projecting spout is a reliable method for the selective induction of esophageal carcinoma in dog.

Topics: Administration, Oral; Animals; Carcinogens; Carcinoma, Squamous Cell; Dogs; Esophageal Neoplasms; Female; Male; Methylnitronitrosoguanidine; Papilloma; Stomach Neoplasms

Topics: Adenocarcinoma; Animals; Carcinoma, Squamous Cell; Dogs; Dose-Response Relationship, Drug; Esophageal Neoplasms; Male; Methylnitronitrosoguanidine; Stomach Neoplasms

In order to obtain a reliable experimental model simulating human esophageal cancer, endoscopic and histopathological studies were undertaken in the esophageal cancer produced in the beagle dog. Thirty-seven dogs had been given a solution of N-Ethyl-N'-nitro-N-nitrosoguanidine (ENNG) at a concentration of 150 micrograms/ml for 3-9 months. Follow-up studies included serial endoscopy and biopsy, and almost all animals were eventually sacrificed for histological examination. The results were as follows: Squamous cell carcinoma was observed in 5 out of 22 female dogs, while none in male dogs at all. For the induction of squamous cell carcinoma in the esophagus, administration in the condition of 150 micrograms/ml (75mg/day) for 6-9 months was most suitable. Almost all of esophageal lesions were protruding and well-differentiated squamous cell carcinoma with invasion of the submucosa. The stages of hyperplasia, dysplasia and squamous cell carcinoma in the esophagus were chronologically followed. Carcinoma had been observed in the stomach about 4 months prior to the appearance of esophageal carcinoma. This experimental model was proved to be useful for studies on histogenesis of human esophageal cancer both light and electron microscopically.

Topics: Animals; Carcinoma, Squamous Cell; Dogs; Esophageal Neoplasms; Female; Male; Methylnitronitrosoguanidine; Microscopy, Electron; Sex Factors; Stomach Neoplasms

An endoscopical study of chronological change during the carcinogenetic process of cancer of the esophagus induced by N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) in 16 male beagle dogs was performed to clarity whether or not precancerous lesions exist in the esophagus. Redness was first observed in the mucosa in the lower and/or middle portions of the esophagus. A small nodule developed in the redness, followed by a nodule. The nodule then developed into a flat polyp which finally developed into lesions such as an elevated lesions, protrusions or elevations with depressions. Histologically, esophagitis or acanthosis in the redness and acanthosis were found in most of the small nodules. With regard to the nodules, papillomatosis was observed in half of the lesions, while either acanthosis or atypical epithelial proliferation were found in most of the flat polyps. Almost all the elevated or protruding lesions were found to be carcinoma.

Topics: Animals; Biopsy; Carcinogens; Cell Transformation, Neoplastic; Dogs; Esophageal Neoplasms; Esophagoscopy; Esophagus; Male; Methylnitronitrosoguanidine

Topics: Animals; Carcinogens; Carcinoma, Squamous Cell; Dogs; Epithelium; Esophageal Neoplasms; Male; Methylnitronitrosoguanidine; Neoplasms, Experimental

Topics: Animals; Carcinoma, Squamous Cell; Dogs; Esophageal Neoplasms; Male; Methylnitronitrosoguanidine

Early changes in the esophageal mucosa of dogs induced by N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) were studied. Seven one-year-old beagle dogs were given a solution of 250 micrograms ENNG/ml to drink ad libitum for 4 months. Three different kinds of lesions (10 erosive carcinomas, 4 slightly elevated microcarcinomas and 19 leukoplakias) were recognized. These three kinds of lesions were not located adjacent to one another, and were surrounded by almost normal stratified squamous epithelium. The foci of the carcinomas revealed an abrupt transition to normal epithelium and were considered to have arisen abruptly from normal esophageal epithelium. The histogenesis of squamous cell carcinomas of the esophagus in dogs may differ from that in man.

Topics: Animals; Carcinoma; Carcinoma, Squamous Cell; Dogs; Esophageal Neoplasms; Leukoplakia; Male; Methylnitronitrosoguanidine; Neoplasms, Experimental