IgA heavy chain disease. A case detected in the western hemisphere.

IgA heavy chain disease (alpha chain disease) was detected in a 46 year old South American (Colombian) of mixed Spanish and Indian (Mestizo) descent. The clinical course was characterized by severe malabsorption, initially thought to be a variant of tropical sprue. Jejunal mucosal biopsy revealed marked villous atrophy with heavy infiltration of the lamina propria by a single monotonous cell type which, by light microscopy, had the appearance of either a large, abnormal plasma cell or a small histiocyte. Electron microscopy of the biopsy specimen demonstrated the presence of abnormal plasma cells, lymphatic distention and abnormalities of surface epithelial cells. At autopsy a 6 by 3 cm mass was found in the right para-aortic area along with many firm 2 cm mesenteric and para-aortic lymph nodes. Histologic examination revealed the presence of a monotonous cell type similar to that found in the jejunal mucosal biopsy specimen.

Tropical sprue in American servicemen following return from Vietnam.

Moderately severe tropical sprue was diagnosed in two American servicemen 15 and 19 months after return from Vietnam. Intestinal parasites were not demonstrated, and clinical, laboratory, and jejunal histological abnormalities returned to normal following treatment with tetracycline and folic acid in one patient and folic acid alone in the other. Neither patient was anemic, although one had hypersegmented polymorphonuclear leukocytes and both had macrocytosis and megaloblastic bone marrows. In each of these patients, diagnosis was delayed because of the failure to consider tropical sprue in the differential diagnosis of diarrhea and weight loss. The findings in these patients indicate that individuals from nonendemic areas who reside in Vietnam are at risk of developing overt tropical sprue.

Cytotoxicity of a cell free extract of Entamoeba histolytica.

Previous attempts to demonstrate toxicity of cell-free extracts prepared from axenically cultivated E. histolytica have proved unsuccessful. We report here the successful production of cytopathic effect by cell-free extracts of two strains (HM-1 and HK-9) of E. histolytica in tissue culture monolayers. The cytotoxic effect demonstrated was sensitive to serum in the assay medium. Failure of past investigations to demonstrate cytotoxic activity may be explained by the presence of serum in the assay systems used.

Light and electron microscopic studies of antibiotic associated colitis in the hamster.

Lincomycin and its analogue, clindamycin, are capable of producing mild to severe colonic mucosal injury in humans (antibiotic associated colitis). Patients with the disorder may have severe diarrhoea, pseudomembranous plaques, confluent pseudomembranes, and/or a frank, diffuse haemorrhagic colitis. The present study was designed to assess the Golden Syrian hamster as an animal model for antibiotic associated colitis and to describe lesions seen in the animal model by light, transmission electron, and scanning electron microscopy. A colitis was produced in Golden Syrian hamsters by oral or parenteral administration of lincomycin, clindamycin, or N-demethyl clindamycin. Animals were killed at intervals and microscopic studies made of sequential morphological changes in the ileum, caecum, and colon. The microscopic lesions in the early stages of the disorder were abnormalities within the brush border, cellular oedema, and hyperaemia. Changes in the intracellular organelles were observed in more severely damaged epithelial cells. Epithelial hyperplasia resulted in the piling up of cells on the mucosal surfaces. In specimens with the most severe damage, complete loss of epithelium from the mucosal surface was observed. Pseudomembranous plaques were occasionally seen. Comparison of the clinical, gross, and histological features of the animal disease with the human disorder suggest that, although minor differences are present, the hamster model is suitable for experimental studies of antibiotic associated colitis.