Pathogenicity of Staphylococcus aureus phage type 3A/3C/55/71 and Staphylococcus sciuri in germfree euthymic and athymic mice after intravenous infection

To evaluate the possibility ofprotecting our colonies of small laboratory animals against Staphylococcus aureus infections by preassociation with the rodent specific Staphylococcus sciuri, it was first of all necessary to determine the pathogenicity of the S. sciuri strain under consideration. Germfree euthymic Han: NMRI and athymic (T-cell deficient) Han:NMRInu/nu mice were injected intravenously with increasing doses of S. sciuri strain 908/1. S. aureus (phage type 3A/3C/55/71) which is known to cause health problems in SPF colonies of the above mentioned strains of mice was used for comparison.S. aureus infections exhibited a dosedependent morbidity and mortality in both strains of mice. In contrast, S. sciuri did not cause any lethal infection but produced sporadically mild purulent processes in the euthymic mice. Due to the use of relatively small groups a statistical evaluation can only show tendenc1es

Spontaneous neoplastic lesions in Harlan Sprague-Dawley rats

In a 24-months study, the spontaneous tumour spectrum of the Hsd:Sprague-Dawley stock was examined. Pituitary gland tumours were found in 20 per cent of the males and 39 per cent of the females. This relatively low incidence, compared to other SPRD stocks, had little effect on the survival of the females (50 per cent), due to the high incidence (76 per cent) of mammary gland tumours (predominantly fibroadenomas) resulted in unscheduled sacrifices of many female. Other common neoplasms in Hsd:Sprague-Dawley rats were benign medullary tumours (27 per cent in males, 11 per cent in females), C-cell adenomas (23 per cent in males, 28 per cent in females), and endometrial stromal polyps (22 per cent in females)

Spontaneous cystic keratinizing epithelioma in the lung of a Sprague-Dawley rat

A spontaneous cystic keratinizing epithelioma in the lung of a 704-days-old female Hsd:Sprague-Dawley rat is described. The rat has a white subpleural discoloration on 1 diaphragmatic lobe at necrospy. Microscopically, a central keratin mass, surrounded by a multilayered squamous epithelium of varying thickness, was found. In the periphery of the tumor, epithelial nests projected multifocally into the adjacent alveolar spaces. Immunohistochemical labeling of nuclei by PNAC (proliferating cell nuclear antigen) revealed proliferative activity in 1 or 2 peripheral cell layers in most locations. To the best of the authors' knowledge, this is the first report dealing with the morphological and immunohistochemical features of a spontaneous cystic keratinizing epithelioma in a rat