RESUMO
In rats, chondrosarcomas have been reported to occur both spontaneously and secondary to chemical induction. In a rare case, a spontaneous chondrosarcoma was identified in the deformed femur of a young male Wistar rat. After gross examination of the femur and knee joint, tissue was collected and preserved. The formalin-fixed tissue was decalcified, embedded in paraffin, sectioned, and stained with hematoxylin and eosin. Microscopic examinations revealed a large, highly proliferative, noncapsulated growth of chondrocytic or chondroblastic origin in the femoral bone, with proliferating chondrocytes invading the bone and surrounding tissues in an infiltrative growth pattern. Based on its histomorphological features, the lesion was diagnosed as a malignant cartilaginous neoplasm of spontaneous origin.
RESUMO
Tacrine was evaluated for its mutagenic and clastogenic activities using the Ames bacterial reverse-mutation assay and the rodent bone marrow micronucleus assay. Tacrine was tested for mutagenic potential at six different concentrations, with 1,250 µg/plate as the highest concentration, followed by five lower concentrations with 2-fold spacing. In clastogenic evaluation, tacrine was administered orally to Wistar rats for 2 days at 5, 10, and 20 mg/kg body weights to assess micronucleus induction in bone marrow erythrocytes. In the Ames assay, tacrine showed nonmutagenicity in four tester strains of Salmonella typhimurium viz. TA98, TA100, TA102, and TA1535, but it was found to be mutagenic in the TA1537 tester strain, both in the presence and absence of a metabolic activation system. Tacrine was found to be nonclastogenic on bone marrow cells of rats at all doses tested and was found to be mutagenic in only the TA1537 strain of Salmonella.