Browsing by Author "Cabrita, AM"
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- Cancer inhibition by normal differentiated cellsPublication . Martins, FC; Botelho, MF; Cabrita, AM; Oliveira, CF
- Influence of normal mammary epithelium on breast cancer progression: the protective role of early pregnancyPublication . Martins, FC; Botelho, MF; Cabrita, AM; Oliveira, CFAIMS AND BACKGROUND: The microenvironment has a well recognized role in breast cancer progression. Despite different theories, the mechanism of early pregnancy protection in mammary carcinogenesis is unknown. Since pregnancy is responsible for mammary gland differentiation, we tested the hypothesis that differentiated mammary epithelial cells may inhibit breast cancer progression. In other words, the protective role of early pregnancy could be due to the inhibitory influences of the more differentiated mammary tissue. METHODS: In order to test our hypothesis, we used 30 female Balb/c nude mice and MCF-7 cells of breast adenocarcinoma. The female mice were divided into two test groups, group I (GI) and group II (GII), and a control group. In GII, the animals were submitted to epithelial removal in the left fourth inguinal mammary gland at 3 weeks of age. Both groups were given continuous hormonal treatment to simulate the pregnancy development of the mammary gland. Two million MCF-7 cells were then injected into the fourth inguinal mammary gland (GI) or in the respective cleared mammary fat pad (GII). Five weeks later the mice were sacrificed and their tumors removed. Tumor development rates and tumor volumes were determined and proliferation and apoptosis were evaluated by immunohistochemistry. RESULTS: Tumors of GII mice had a larger mean volume than those of GI mice (P = 0.001, Mann-Whitney U-test) and an apparent increase in proliferation, demonstrated by a higher staining intensity for proliferating cell nuclear antigen (PCNA). As tumors presented caspase 8 staining, there may be apoptotic activation involved in cell death, mainly through an extrinsic pathway. CONCLUSIONS: These results suggest that a differentiated intact mammary gland may have an inhibitory influence on mammary tumor growth in mice.
- Pregnancy and its role in breast cancerPublication . Martins, FC; Botelho, MF; Laranjo, M; Cabrita, AM; Torgal, MI; Oliveira, CFEarly full-term pregnancy is the only recognized factor able to prevent breast cancer. There are several hypotheses to explain the mechanisms of this protection, namely an altered hormonal milieu, a differentiation process or a switch in stem cell properties. To explore them, authors have been using animal models, mainly in rodents. Hormonal administration with estrogen and progesterone was the most widely used process to mimic the mammary changes during pregnancy. We have recently proposed that this enigmatic protective role of a full-term birth in breast cancer is carried out by tumor inhibition mediated by differentiated mammary epithelial cells. This explanation may give a new perspective of breast cancer prevention and treatment.
- Techniques of intestinal transplantation in ratPublication . Lopes, MF; Cartucho, DJ; Cabrita, AM; Patrício, JTwo surgical models of intestinal transplantation in the rat are described. One is the implantation of fetal and newborn intestine as free grafts into the omentum of adult recipients, the other the adult intestine transplantation as an accessory graft using vascular anastomoses. A hundred and sixteen small-bowel transplantations were done; 36 of which were fetal intestine (group I), 40 of newborn intestine (group II), and 40 of adult intestine (group III). In the fetal and newborn intestinal transplantation, we emphasize the practices that allowed us to avoid ischemic and traumatic injury to the graft. In the adult intestine transplantation with vascular anastomoses, we heighten the modifications in the surgical technique that made the operation easier and the strategies used to prevent hypothermia and hypovolemic shock. Once experienced with the two chosen surgical techniques, transplantation using an avascular segment became much easier and quicker than transplantation with vascular anastomoses