Sequential studies on the histopathogenesis of gastric carcinoma in rats by a weak gastric carcinogen, N-propyl-N'-nitro-N-nitrosoguanidine

Sequential studies were made on the histopathologic changes in the glandular stomach of rats induced by a weak carcinogen. N-propyl-N'-nitro-N-nitrosoguanidine (PNNG). Fiftyfour rats were given 100 micrograms/ml of PNNG in their drinking water for 44 weeks, and then normal tap water until the end of the experiment. Rats were killed at intervals between week 1 and week 88. No marked atrophy or ulceration of the mucosa was found between week 1 and the end of the experiment. Focal intestinal metaplasia was found in week 19 and its incidence increased during the experiment. Adenocarcinoma in situ with extreme cellular atypia was found in mucosa with a normal appearance in week 67. An adenocarcinoma invading the submucosa was found in week 69, and one invading the serosa in week 88. All these pathological lesions were found on the anal side of the pyloric region. No pathologic changes were found in the fundic region. The sequential changes of the mucosa of the glandular stomach induced by this weak gastric carcinogen, PNNG, were very different from those induced by the potent gastric carcinogen, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Gastric carcinoma induced by PNNG seems to be more similar to human gastric cancer than that induced by MNNG.

Distribution of marker enzymes and mucin in intestinal metaplasia in human stomach and relation to complete and incomplete types of intestinal metaplasia to minute gastric carcinomas

Intestinal metaplasia of the human stomach was classified into two types, complete and incomplete. The complete type was associated with the intestinal marker enzymes sucrose alpha-D-glucohydrolase, alpha, alpha-trehalase, aminopeptidase (microsomal) (APM), and alkaline phosphatase (ALP). Tissue of this type contained goblet cells and Paneth's cells but not high-iron diamine (HID)-positive mucin staining with HID-Alcian blue. The incomplete type of intestinal metaplasia was associated with sucrose alpha-D-glucohydrolase, APM, goblet cells, and HID-positive mucin but not with alpha, alpha-trehalase, ALP, or Paneth's cells. For the examination of the distribution of the complete and incomplete types in 84, 27, and 16 resected specimens of human stomach with gastric carcinoma, gastric ulcer, and duodenal ulcer, respectively, disaccharidases were located with Tes-Tape. Specimens with intestinal metaplasia were divided into three classes: complete type only (class I), incomplete type only (class II), and a mixture of areas of the complete and incomplete types (class III). Of the 84 specimens from patients with gastric carcinoma, intestinal metaplasia was found in 76 (01%), and the percentages of specimens of classes I, II, and III were 32, 22, and 46, respectively. In these specimens, the percent incidence of class I increased and that of class II decreased with age. Of the 27 specimens from patients with gastric ulcer, 16 (59%) shopwed intestinal metaplasia and 10 of the 16 (63%) specimens were of class II. Of the 16 specimens from patients with duodenal ulcer, only 3 (19%) specimens showed intestinal metaplasia and all of them were of class II. The relationships of the complete and incomplete types of intestinal metaplasia to gastric carcinoma wre studied in 26 foci of minute carcinoma of the stomach less than 5 mm in largest diameter. Nineteen of 20 (05%) foci of the intestinal type of minute carcinoma were surrounded by intestinal metaplasia and 16 foci (80%) were surrounded by the incomplete type of intestinal metaplasia.

Carcinoma of the esophagus of rabbits induced with N-methyl-benzylamine and sodium nitrite

Esophageal carcinomas were induced in three of five rabbits given 0.25% N-methylbenzylamine and 0.16% NaNO2 in their drinking water. The three rabbits with carcinoma had consumed more than 94 g of NaNO2 and had survived for more than 536 experimental days. The esophageal carcinomas were a slightly elevated type, and no polypoid lesions were seen. They were classified histologically as squamous cell carcinomas or adenosquamous carcinomas, or both. No metastases were found. The other two of the five rabbits died early in the experiment before any esophageal carcinoma had developed.

Changes in peroxisomes in preneoplastic liver of rats induced by 3'-methyl-4-dimethylaminoazobenzene

Histochemical investigations used the 3,3'-diaminobenzidine reaction to demonstrate the catalase activity and thus variations in numbers of peroxisomes, and electron microscopic examinations were made of hyperplastic liver lesions in rats fed 0.06%3'-methyl-4-dimethylaminoazobenzene. At the 10th week of carcinogen feeding, hyperplastic lesions (hyperplastic foci, areas, and nodules) appeared and advanced to further stages. Most of the foci and some of the areas and nodules showed very low catalase activity and, correspondingly, a small number of peroxisomes. When rats were administered ethyl-alpha-p-chlorophenoxyisobutyrate, most of the foci, areas, and nodules showed a moderate increase in catalase activity and in peroxisome number. Hyperplastic foci seemed to grow larger with time to form hyperplastic areas and/or nodules, mostly accompanying maturation as well as proliferation of the hepatocytes involved. Maturation is well characterized by an increase in the endogenous level of catalase and in the number of peroxisomes, as well as by an enhancement of the responsiveness to ethyl-alpha-p-chlorophenoxyisobutyrate. However, there was a small proportion of lesions in which all cells or some cells did not mature and thus were considered persistently altered. It is suggested that these altered cells serve mainly as intimate precursors of hepatomas.

Glomiform and fibrillar cytoplasmic inclusions

Glomiform inclusions, also called tubular arrays in endoplasmic reticulum, are found in the epithelial cells of glandular tissues of a patient with systemic lupus erythematosus, a patient with Reye's syndrome, and a dog. Their three dimensional structure is interpreted as a skein of contorted tubules of endoplasmic reticulum. Fibrillar inclusions found in the pancreatic acinar cells of two patients are believed to represent altered zymogen granules.

Concentric nuclear inclusions

Membrane bound concentric lamellar inclusions were found in the nuclei of pancreatic acinar cells of a patient with multiple primary neoplasms and in the parotid acinar cells of a patient with systemic lupus erythematosus. It is proposed that these inclusions form from rough cisternae sequestered in the nucleus.

Experimental porphyria induced by 3-(2,4,6-trimethylphenyl)-thioethyl)-4 methylsydnone

Administration of 3-[2-(2,4,6-trimethylphenyl)-thioethyl]-4-methylsydnone (TTMS) induces hepatic porphyria in rats, mice and dogs. The protoporphyrin pigment in livers of rats and mice is found mainly in bile ducts and leads to bile duct proliferation and portal inflammation. Dog livers contain protoporphyrin predominantly in bile canaliculi. The birefringence of the pigment appears to be associated with bilamellar components within the pigment. The markedly depressed catalase activity in livers of rats does not increase after clofibrate administration. The catalase activity of mouse liver is depressed slightly and responds to clofibrate treatment.

Peroxisomes in liver tumors of rats induced by 3'-methyl-4-(dimethylamino)azobenzene

Peroxisomes were present in trabecular carcinoma and adenocarcinoma induced by 3-methyl-4-(dimethylamino)azobenzene in the liver of rats. Peroxisomes in well-differentiated trabecular carcinoma (type I) resembled more or less those in hepatocytes in their electron microscopic features, but were considerably small in number. Poorly differentiated trabecular carcinoma (type II) and adenocarcinoma contained peroxisomes in far smaller number than in the well-differentiated trabecular carcinoma, or frequently showed no peroxisomes. Peroxisomes in poorly differentiated trabecular carcinoma and adenocarcinoma were small in size, contained scanty matrix in general, and almost lacked crystalloid nucleoids; however, they were easily identified by electron microscopic cytochemistry of catalase. Catalase activity of these tumors was significantly lower than in the liver tissues. These tumors did not respond to ethyl chlorophenxyisobutyrate either by proliferation of peroxisomes or by elevation of catalase activity. It is thus suggested that the cellular mechanisms for regulating the formation of peroxisomes and synthesis of the enzyme involved are impaired in the tumor cells.

Response of microbodies in Morris hepatoma 9618A to clofibrate

Regulation of the formation of microbodies in Morris hepatoma 9618A was studied by examination of the response of the organelles to clofibrate. The fine structures of microbodies in the hepatoma cells closely resembled those in hepatocytes of normal adult rats. In clofibrate-treated rats, the tumor cells showed a slight increase in the size of microbodies and in catalase activity; however, the tumor microbodies did not increase in number. In contrast, in adult clofibrate-treated rats and rats on the day of birth whose mothers received clofibrate during the gestation period, the hepatocytes showed microbodies that were greater in both number and size, and the catalase activity in the liver was definitely elevated.