Marcela Freire Vallim de Mello

Distribution of collagen types I, III, and IV in gastric tissue of marmosets (Callithrix spp., Callitrichidae: Primates)

Extracellular matrix (ECM) components such as fibrillar collagens play a fundamental role in wound repair and have also been studied in association with the gastric ulcer healing process in gastroenterology. Nevertheless, there have been no studies in the literature to date regarding the description and characterization of ECM components, neither in normal nor in injured gastric tissue of primate species. The objective of this study was to investigate the expression of gastric collagen types I, III, and IV in marmosets (Callithrix sp.). Histological specimens from the stomach of 6 Callithrix jacchus, 12 C. kuhli, and 12 C. geoffroyi were evaluated. The specimens were immunostained with anti-types I and III collagen polyclonal antibodies and anti-type IV collagen monoclonal antibody. Collagen types I and III were detected in the submucosa and lamina propria between the mucosal glands while collagen type IV was detected in the muscularis mucosae, muscular layers, blood vessels, and gastric mucosa between the mucosal glands. It is hoped that these findings can contribute to future studies on the gastric extracellular matrix components in primates and to comparative studies in the area of gastroenterology.

TP53 gene expression levels and tumor aggressiveness in canine mammary carcinomas

The protein p53 is considered to be one of the most important tumor suppressor factors. Despite this importance, a potential association between TP53 messenger (m)RNA levels and tumor aggressiveness has not been well defined in animal cancer. We assessed and correlated TP53 gene expression in 40 canine mammary carcinomas with histologic grade, tumor size, and aggressiveness. The tumors were subjected to histologic analysis and the TP53 mRNA levels determined by RT-rtPCR. Statistical analysis revealed no correlation between levels of TP53 mRNA and tumor aggressiveness (r = 0.00) or tumor growth (r = 0.06). Histologic grades (r = 0.17) and mitosis count (r = 0.12) showed a weak correlation with TP53 mRNA expression levels. These findings are consistent with molecular studies that revealed heterogeneous expression of TP53 in canine and human mammary tumors. Hence, TP53 gene expression alone cannot be considered a marker for tumor aggressiveness in canine mammary carcinomas.