Spontaneous rat malignant tumors of fibrohistiocytic origin: an ultrastructural study.
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Abdomen↗
Biomedical subjects
P Greaves
Publications and source records attributed to P Greaves.
Microbial contamination of enteral feeds.
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Bacillus cereus↗
Spontaneous fibrous histiocytic neoplasms in rats.
A total of 85 spontaneous rat fibrohistiocytic tumours were evaluated histologically and assessed for the presence or absence of metastases. The overall incidence in controls from 2-year carcinogenicity studies was 2.7%. The tumours occurred principally in the subcutaneous and deep soft tissues, and generally appeared after 18 months of age. Four histological types were recognized: histiocytic (17%), pleomorphic (33%), cellular (17%) and very fibrous (33%). Histiocytic tumours were highly malignant, and most produced metastases. Pleomorphic and cellular neoplasms occasionally produced metastases and must be regarded as potentially malignant. Very fibrous lesions were essentially benign. The close resemblance, both histologically and biologically, between rat and human fibrohistiocytic neoplasms supports the use of the fibrohistiocytic concept in laboratory-animal pathology. Study of these rat tumours may provide insight into the development of human fibrohistiocytic neoplasms.
Age Factors↗
Transitional mucosa and survival in human colorectal cancer.
The mucosa in 100 segments of colon and rectum resected for cancer were examined using light microscopy and histochemical techniques. The extent of abnormal or transitional mucosa was defined for each case. Transitional mucosa was present in 93 of 95 adenocarcinomas and one malignant melanoma. The average total length of transitional change was 3.4 cm the maximum length was 19.5 cm. An inverse correlation was observed between the survival and the length of transitional mucosa around locally invasive (Dukes' B) carcinomas (P = 0.005). This may be related to increased amounts of sialic acid in transitional mucosa and the ability of sialic acid to depress tumor immunogenicity. The raised levels of sialic acids in transitional mucosa may have practical value in assessment of prognosis in colorectal cancer.
Adenocarcinoma↗
"Have you seen this?" Diffuse hepatic apoptosis.
One important cell death pathway involves binding of the cell surface receptor Fas, which recruits and activates specific initiator and effector caspases. In this study Balb/c mice were injected with monoclonal antibody to Fas either alone or followed by the tripeptide caspase inhibitor Z-VAD.fmk. At four hours mice were killed along with concurrent controls and tissues processed for histological examination and immunocytochemical staining for cleaved caspase-3. The livers in all animals treated with Fas alone showed massive apoptosis and positive staining for cleaved caspase-3 whereas those treated with Fas and Z-VAD.fmk or controls showed little or no apoptosis or staining for cleaved caspase-3. These features suggest that massive apoptosis may be important in fulminant liver disease.
Amino Acid Chloromethyl Ketones↗
Toxicologic lesions associated with two related inhibitors of oxidosqualene cyclase in the dog and mouse.
Two novel hypolipidaemic agents, both members of the aminopyrimidine series, with a mode of action of inhibition of oxidosqualene cyclase (OSC), were administered orally to dogs and mice for 14 and 28 days. Both compounds produced a similar spectrum of pathologic changes. In dogs, the agents produced equatorial single cell necrosis and cataract in the lens (also observed clinically); atrophy, ulceration, and inflammation of the cornea; hyperkeratosis, acanthosis, hair papillary atrophy, and inflammation of the skin; and epithelial degeneration and sperm granuloma in the epididymides. One female dog showed signs of liver toxicity. In mice, severe cataract formation was seen with both compounds, and liver toxicity was produced by one of the compounds. The severity and speed of onset of the cataract formation were very marked. The changes seen were dissimilar to those reported with the most commonly used class of hypolipidaemic agents in the clinic, the hydroxymethyl glutaryl coenzyme A (HMGCoA) reductase inhibitors but were reminiscent of those reported for the hypolipidaemic agent Triparanol. which was predictive of toxicity seen in man.
Administration, Oral↗