Minimal invasive carcinoma of the colon in rats.

The careful histologic examination of the macroscopically normal colon in rats treated 8 months previously with a single dose of the colonotropic carcinogen dimethylhydrazine (DMH) demonstrated atypical colonic glands in normally occurring lymphoid mucosal patches. The atypical glands were characterized by the absence of cytoplasmic mucus, hyperchromatic cell nuclei, cell stratification, and increased number of mitotic figures. In 61.7% of the experimental animals, atypical colonic glands were found beyond the boundary of the muscularis mucosae, but in none of the controls. Thus, microinvasive adenocarcinoma of the colon seems to be a common finding in rats treated with a single dose of DMH. These adenocarcinomas remain, however, undetected at macroscopic examination. Measurements performed in consecutive lymphoid aggregates demonstrated that 50% of rats receiving DMH had thicker lymphoid aggregates than control animals. In spite of this, no tumor was recorded at naked eye examination in these areas. The macroscopic examination appears to be an unreliable method of ruling out malignancy in experimental rats treated with a single dose of the above-mentioned carcinogen.     

Generalised tuberculosis in a patient with acquired immunodeficiency syndrome

We describe a heroin addict who presented with cellular immunodeficiency, generalised tuberculosis, and pneumonia caused by Pneumocystis carinii, and discuss the risk of these associations.     

Intraepithelial bodies in colorectal adenomas: Leuchtenberger bodies revisited

The presence of intraepithelial inclusion bodies (Leuchtenberger bodies) was recorded in rectal or colonic specimens from 130 patients. Large to moderate number of intraepithelial bodies were recorded in 81.8 percent of 55 colorectal adenomas from patients with familial adenomatous polyposis (FAP). Conversely, none of the 55 non-FAP adenomas or of the 20 specimens with ulcerative colitis (10 with dysplasia) had similar amounts of intraepithelial granules. Feulgen studies demonstrated that the granules contain DNA and are probably nuclear fragments of destroyed lymphocytes. Although the pathogenesis of this phenomenom remains obscure, it appears that the presence of large to moderate number of intraepithelial bodies in colorectal adenomas should strongly raise the suspicion of FAP.     

Cell kinetics of rat gastrointestinal mucosa. Autoradiographic study after treatment with 15(R)15-methyl-prostaglandin E2

Forty Sprague Dawley rats (120 g) were divided in groups of five rats each, and 2 mg , kg-1 15(R)15-methyl-prostaglandin E2 or vehicle was administered orally, twice daily for 5 days. On the 6th day, 1 mCi . kg-1 methyl-3H-thymidine was given intraperitoneally to all rats. Groups of rats were killed at 45 min and 24 h, 72, and 120 h after the labelling. Treatments were continued until death. Samples were taken from the corpus, antrum, and jejunum and processed for autoradiography. Microscopic evaluation of the proliferative and functional compartments included cell counts and determination of the labelling index (LI) and mitotic index (MI). Prostaglandin treatment increased the number of cells in the jejunal and gastric epithelia. The DNA synthesis, evaluated from the LI and 45 min after thymidine injection, was unaffected by treatment. The clearance of label from jejunal crypts and villi was significantly slower in the prostaglandin groups. Similar observations were made in the proliferative zone of the corporal and antral epithelia. The MI was unchanged or reduced by prostaglandin treatment, the reduction being significant after 8 to 10 days' treatment. It is suggested that the trophic action of prostaglandin E2 is produced by reduction of epithelial cell losses, thereby prolonging the cell survival time. The reduced MI may be secondary to negative feedback from the hyperplastic epithelium. Trophic actions are produced by short-term treatments.