Evaluation of the global DNA methylation in canine mast cell tumour samples by immunostaining of 5-methyl cytosine.

Cutaneous mast cell tumours (MCT) are the most common skin tumour in dogs, and to our knowledge, there are no previous studies regarding the global methylation of these tumours. DNA hypomethylation and hypermethylation have been described in several tumours and both mechanisms can lead to carcinogenesis. The purpose of this study was to evaluate the global DNA methylation in canine MCT. A total of 48 MCT samples were classified in grades 1, 2 and 3 or high-grade or low-grade. Monoclonal antibodies were used for the immunohistochemical detection of the 5-methylcytosine. The immunostained nuclei were classified in strong, weak or negative pattern, and these were quantified in five distinct microscopic fields (40× objective) in each slide. The results showed that global DNA hypomethylation was predominant in grade 3, high-grade, less differentiated MCT. These epigenetic changes in neoplastic mast cells warrant further detailed investigation aiming the establishment of tumour epigenetic therapies.

Evaluation of DNA damage by the alkaline comet assay of the olfactory and respiratory epithelia of dogs from the city of São Paulo, Brazil.

Animals kept as pets may be considered sentinels for environmental factors to which humans could be exposed. Olfactory and respiratory epithelia are directly subjected to airborne factors, which could cause DNA lesions, and the alkaline comet assay is considered a reliable tool for the assessment of DNA damage. The objective of this work is to evaluate the extent of DNA damage by the comet assay of the olfactory and respiratory epithelia of dogs from different regions of the city of São Paulo, Brazil. Thirty-three clinically healthy dogs, aged 5 years or more, were used in the study, with 7 from the North region of São Paulo, 7 from the South region, 3 dogs from the East region, and 16 dogs from the West city region. Three dogs younger than 6 months were used as controls. DNA damage was analyzed by the alkaline comet assay. We observed no difference in histopathological analysis of olfactory and respiratory epithelia between dogs from different regions of São Paulo. Dogs older than 5 years presented significantly higher comet length in both olfactory and respiratory epithelia, when compared with controls, indicating DNA damage. When separated by regions, olfactory and respiratory epithelia presented similar DNA damage in dogs from different regions of São Paulo, corroborating with similar levels of particulate matter index (PM10) in all regions of the city. In this study, we report for the first time that the comet assay can be used to quantify the extent of DNA damage in dog olfactory and respiratory epithelia, and that comet length (DNA damage) increases with age, probably due to environmental factors. Air pollution, as measured by PM10, can be responsible for this DNA damage.

Immunohistochemical characterization of canine prostatic intraepithelial neoplasia.

The development of prostate cancer is believed to be a multistep process, progressing sequentially from normal epithelium, to prostatic intraepithelial neoplasia (PIN) and, finally, to invasive neoplasia. Malignant stem cells within the basal cell layer of the prostatic epithelium are believed to play an important role in the failure of androgen-ablation therapy that occurs in the most advanced form of prostate cancer. The aim of the present study was to immunohistochemically characterize the lesions of canine PIN. Prostatic tissue from five dogs with PIN was compared with normal prostate tissue from nine further dogs. There was an increase in the number of basal epithelial cells in lesions consistent with PIN as defined by expression of the nuclear protein p63. These lesions had elevated expression of proliferating cell nuclear antigen (PCNA) and heterogeneous labelling for the nuclear androgen receptor (AR). These findings suggest that the basal cells present in PIN may play a role in canine prostate carcinogenesis and that the proliferation of these cells occurs despite the heterogeneous expression of the AR.

Ocorrência da dermatofilose (dermatophilus congolensis) em suínos criados no estado de são paulo, brasil

ABSTRACT We describe the occurrence of dermatophilosis in adult pigs admitted at the Clinic for Cattle in the Center for Research and Diagnostics of Ruminant Diseases in the School of Veterinary Medicine at University of São Paulo, Brazil. The sick animals had an exudative epidermitis, characterized by the presence of easily removable scabs with an underlying purulent exsudate. The lesions were observed mainly on the animals backs and ears. The smear of the scabs and secretions revealed the presence of structures that were similar to coccus which were displayed in filaments and were morphologically similar to the Dermatophilus congolensis zoospore. The diagnosis was confirmed by skin biopsy and by the isolation of the etiologic agent from samples collected from the sick animals.

RESUMO Descreveu-se a ocorrência da Dermatofilose em suínos adultos atendidos pela Clínica de Bovinos do Centro de Pesquisa e Diagnóstico de Enfermidades de Ruminantes da Faculdade de Medicina Veterinária e Zootecnia da Universidade de São Paulo. Os animais enfermos apresentaram uma epidermite exsudativa caracterizada pela formação de crostas que se destacavam com facilidade e que apresentavam uma secreção com aspecto purulento, principalmente nas regiões do dorso e nas orelhas dos animais. Os esfregaços das crostas e secreções revelaram a presença de estruturas similares a cocos que se arranjavam em filamentos, morfologicamente semelhantes ao zoósporo do Dermatophilus congolensis, sendo a confirmação do diagnóstico realizada por biopsia de pele e isolamento do agente etiológico da doença em amostras colhidas dos dois animais enfermos.