The effects of different MNNG (N-methyl-N'-nitro-N-nitrosoguanidine)-doses on the stomach and the upper small intestine of the rat. II. The frequency of intestinal metaplasia

N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) was given to 3 groups of male Wistar rats in different doses of 25 micrograms/ml, 50 micrograms/ml and 100 micrograms/ml with their drinking water for 32 weeks. After 50 weeks the antrum region of the stomach was investigated by serial sections. All animals showed tubules with metaplastic intestinal epithelium. The different values of metaplastic glands in the antrum region of the stomach were 187 (25 micrograms MNNG), 76 (50 micrograms MNNG) and 51 (100 micrograms MNNG). They indicate an inverse relationship of the frequency of intestinal metaplasia and the MNNG dose. As opposed to this dose-response pattern, cytotoxic alterations, regenerative hyperplastic lesions and tumours of the stomach are more frequent after medium of high MNNG doses. It is therefore suggested that the induction of intestinal metaplasia is a specific effect of the carcinogen mainly in the low dose range.

The effects of different MNNG (N-methyl-N'-nitro-N-nitrosoguanidine) doses on the stomach and the upper small intestine of the rat. I. The frequency and histopathology of the induced tumours

N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) was given to 3 groups of rats with the drinking water for 32 weeks in different doses: 25, 50 and 100 micrograms/ml. After 50 weeks the induced tumours of the stomach and the upper small intestine were investigated. Most tumours were well differentiated adenocarcinomas or adenomatous-hyperplastic lesions with focal adenocarcinoma. After low MNNG-concentration (25 micrograms/ml) only adenomatous hyperplastic lesions with focal adenocarcinoma were found. A tumour development in connection with intestinal metaplasia was detectable exclusively in two rats of the group receiving 50 micrograms MNNG/ml. The frequency of gastric tumours shows a relatively low peak (3.3 tumours/10 animals) after administering a medium MNNG-concentration (50 micrograms/ml) and a little decrease of the frequency after higher MNNG-concentration, as opposed to the approximately linear dose-related increase of the tumour frequency in the upper small intestine. The highest tumour induction rate was found in the upper small intestine after 100 micrograms MNNG/ml (5.6 tumours/10 rats). It can be concluded that the mucosa of the upper small intestine possesses a greater susceptibility to the carcinogenic effect of MNNG than the glandular stomach of the rat.

Endocrine cells in adenocarcinomas and their prestages in the glandular stomach and duodenum of rats after MNNG administration. Histochemical, electron microscopical and radioimmunological studies

Tumours of the glandular stomach and upper small intestine were induced in rats by oral administration of MNNG. In most cases the lesions were identified histologically as adenocarcinomas and their prestages, such as polypeous and downward growing adenomatous hyperplasias. Out of 48 adenomatous hyperplasias and adenocarcinomas of the stomach and 24 well differentiated adenocarcinomas of the small intestine, we observed argyrophilic cells in nearly the half of the cases. Endocrine cells were also identified by electron microscopy. The frequency of endocrine cells was reduced with decreasing degree of tissue differentiation. In poorly differentiated carcinomas, including signet ring cell carcinomas, no argyrophilic cells were found. Out of 10 adenomatous hyperplasias and tumours of the stomach investigated immunohistochemically, 5 cases showed gastrin producing cells. Most of these animals were radioimmunologically characterized by strongly elevated serum gastrin levels. Derivation and potential relevance of the endocrine cells in tumours are discussed.

[Punch and suction biopsy in the diagnosis of prostatic neoplasms]

133 prostate punch biopsies were examined in histologic way and 90 aspiration biopsies in cytologic way. The histologic and cytologic results of the altogether 116 patients are discussed in connection with the differently tentative findings of rectal palpation. Prostate punch and aspiration biopsies can be used as completion methods in cancer prophylaxis examination. The all-metal needle after Deutschmann (Zittau/GDR) repeatedly to be used for punch biopsy has proved its worth.

[Intramural diverticulosis and adenomyomatosis of the gallbladder]

Issuing from an own observation the clinical picture of the adenomyomatosis and the intramural diverticulosis of the gall bladder is considered from the clinical, radiological and pathologo-anatomical point of view. The opinions which are not homogeneous are explained and discussed. Also abortive forms may radiologically be proved with probability.