Morphological and biological characterization of two mesenchymal murine tumors and the modulation of their growth parameters by n-3 and n-6 polyunsaturated fatty acids.

Certain tumor growth parameters (GP) of two mesenchymal transplantable tumors maintained on C57BL/6J mice were characterized. Considering that many experimental, clinical and epidemiologic data have indicated that n-3 and n-6 essential fatty acids are nutrients which may delay the development as well as improve the course of cancer, GPs were evaluated on hosts fed on a semisynthetic formula containing 5% of corn oil (CO) or cod liver oil (CLO) and stock diet (C group). Although survival and latency time of tumor-bearing mice were shortened, other GP as percentage of successful implants were improved by both oils in sarcoma-bearing hosts, suggesting that n-3 and n-6 fatty acids might play a modulating role for the development of these tumors.

Morphological aspects of an experimental tumour photosensitized with a meso-substituted cationic porphyrin.

The meso-substituted cationic porphyrin, meso-tetra(4N-methyl-pyridyl)porphine (T4MPyP) appears to be a selective tumour localizer on the basis of pharmacokinetic studies. Irradiation (at 600-680 nm) of an intramuscularly implanted MS-2 fibrosarcoma in Balb/c mice at 24 h after injection of T4MPyP causes tumour necrosis: histological and ultrastructural analyses of tumour specimens taken at different times after phototherapy indicate slowly-appearing tissue damage which involves both malignant cells and the vascular endothelium. At the subcellular level, the membranous systems and nuclei are the main targets of the photoprocess. The tumour necrosis is particularly extensive upon injection of 4.1 mg kg-1 T4MPyP.

Carcinogênese química cutânea e subcutânea em gerbil (Meriones unguiculatus) / Chemical cutaneous and subcutaneous carcinogenesis in gerbil (Meriones unguiculatus)

O comportamento do gerbil (Meriones unguiculatus) como modelo em oncologia experimental é estudado. Aplicaçöes tópicas de 3-metilcolantreno (MC), sobre a pele do dorso, induziram pailomas, carcinomas epidermoides, carcinomas basocelulares e lesöes hiperpigmentadas semelhantes ao nevus azul. Ao contr rio, somente lesöes pigmentadas foram observadas nos animais tratados com MC (iniciaçäo) associado ao óleo de croton (promoçäo). Além disoo, fibrossarcomas e um linfoma foram induzidos com injeçöes subcutâneas de MC.

Initiation of a transplantable fibrosarcoma by the synergism of two non-initiators, alpha-tocopherol and soya oil.

When, in the course of an ageing study, alpha-tocopherol (vitamin E), dissolved in soya oil, was given to 22 Balb/c mice once a week subcutaneously for 10 months, it caused the development of vigorously growing fibrosarcomata at the site of the injections in 17 (77.3%) of the animals. The tumors produced in this manner proved eminently transplantable into syngeneic Balb/c hosts, and have been serially transplanted every 3-4 weeks for over 3 years in such recipients, having reached their 44th transplantation cycle at the present time; upon transplantation, they now exhibit a 100% "take" incidence and proliferate extremely rapidly, growing from pin-head size to up to half the weight of a whole recipient mouse within 3 weeks. All fibrosarcomata showed marked mitotic activity, invasion of adjacent tissues and extensive necrotic areas, and they became more undifferentiated after the third transplantation cycle. Neither pure alpha-tocopherol alone nor soya oil alone produced any tumors when given subcutaneously once a week, for 10 months to groups of 22 Balb/c mice each. It is concluded that the two agents alpha-tocopherol and soya oil which proved non-carcinogenic when injected alone, developed a powerful carcinogenic effect when they acted on subcutaneous connective tissue simultaneously. The possible mechanisms of this phenomenon are discussed.