Browsing by Author "Mega, A."
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- Breves considerações sobre a evolução, impacto e profilaxia do parvovírus caninoPublication . Costa, M.; Nóbrega, C.; Mega, A.; Esteves, F.; Cruz, R.; Santos, C.; Vala, Helena; Santos, M.; Mesquita, J. R.A família Parvoviridae está dividida em duas subfamílias. A subfamília Parvovirinae, que inclui os vírus que afectam vertebrados e a subfamília Densovirinae, que contém os vírus que afectam insectos (MacLachlan & Dubovi, 2011). Dentro da subfamília Parvovirinae foram definidos cinco géneros: Erytrovírus, Dependovírus, Parvovírus, Amdovírus e Bocavírus.
- Characterization of the apoptotic index in canine mastocytomas.Publication . Paiva, D.; Cruz, R.; Mega, A.; Vala, HelenaIntrodution: Studies on apoptosis have been described in several neoplasias. Apoptosis is a biological process of programmed cell death that, due to its important role in oncogenesis, may elucidate some aspects. Objective: Detection of apoptosis in canine mastocytoma to determine its relationship with histologic grading, apoptotic index and prognosis. Material and methods: 12 cases of canine mastocytoma, from the analytic files of the Laboratory of Anatomical Pathology of ESAV. Immunohistochemical methods were implemented, using pro- and anti-apoptotic proteins, Bax and Bcl (Santa Cruz, Biotechnology). Results: All mastocytomas included in this study revealed a positive reaction to the tested antibodies, a more intense reaction was found to pro-apoptotic antibody Bax in comparison to the anti-apoptotic antibody Bcl-2. While Bax expression was more intense in grade I mastocytomas, Bcl-2 had a higher expression in grade III mastocytomas, and both, had a weaker expression in grade II. Conclusion: The decrease of Bax and increase of Bcl-2 expression in accordance with increasing histologic grade, suggests an extension in the life of tumor cells, an increase their number and, consequently, tumoral progression. Canine mastocytomas revealed sensitivity with Bax and Bcl-2 markers and may be applied to apoptotic studies in such tumors to consolidate prognosis in relationship to histologic grading.
- Citologias por aspiração, provenientes de nódulo na narina esquerda (sem envolvimento ósseo), de um canídeo da raça Labrador RetrieverPublication . Vala, Helena; Mesquita, J.; Esteves, F.; Domingues, A. P. C.; Cruz, R.; Santos, C.; Mega, A.O exame histopatológico permite o diagnóstico definitivo, com classificação definitiva e exata, numa percentagem elevada de casos, contudo o exame citológico por ser menos oneroso e rápido é muito adotado na prática clínica diária nos Centros de Atendimento Médico Veterinários, estando descrito como mais indicado em neoplasias sólidas, de origem epitelial, com estroma escasso, linfadenopatias e menos nas neoplasias mesenquimatosas, com estroma abundante, menos propícias à aspiração. Os autores pretendem apresentar o exame microscópico de três preparações citológicas, coradas com Diff-Quik, com o objetivo de fomentar a discussão e determinar o seu diagnóstico definitivo.
- Main difficulties encountered in implementation of techniques for apoptosis detection in animal tissuesPublication . Garcia, C.; Cruz, R.; Mega, A.; Ortiz, A. L.; Teixeira de Lemos, E.; Ferreira, D.; Reis, F.; Vala, HelenaIntroduction: The implementation of methodologies capable of identifying apoptotic cells is a valuable tool in many biomedical studies. Much of the knowledge acquired about the mechanisms regulating apoptosis comes from observations in isolated cells; however, the properties shown by these assays do not always apply to the study of tissue samples. For detection of apoptosis in tissues, many investigators recommend the TUNEL method, nonetheless, other histochemical methodologies are available, and their choice must be carefully evaluated, taking into account the morphologic alterations which they intend to detect. Objective: To share encountered difficulties in the implementation of three different methods for the detection of apoptotic cells in animal tissue. Methods: Animal tissues, fixed in 10% neutral-buffered formalin and embedded in paraffin were submitted to immunohistochemical techniques using the TUNEL method (In situ Cell Death Kit, Roche) and polyclonal Bax and Bcl-2 antibodies (Santa Cruz Biotechnology). Results: After a long period of tests and costs, in which unspecific reactions, as well as several artifacts were obtained, the persistence to overcome these obstacles made all methods effective in the detection of apoptosis. Observed differences in immunolabeling were related to the type of tissues tested, which will be documented in the present study. Conclusions: Immunohistochemical methods are an approach to consider in the detection of apoptosis in animal tissues. Sharing the challenging difficulties found in our work, might obviate many tests and costs in its implementation in other laboratory facilities.
- Rabbit thymic tissue – a potential marker for apoptosis techniques.Publication . Vala, Helena; Santos, C.; Cruz, R.; Nóbrega, C.; Ortiz, A. L.; Mesquita, JR; Esteves, F.; Mega, A.Background: Apoptosis detection methods have been proposed for diagnostic purposes, in particular for determining the biological characteristics of tumours and, indirectly, their prognosis. Implementation of a new technique requires the use of an effective positive control for correct assessment. Most specialty publications on the subject, do not indicate the positive controls used and do not disclose the obtained results therein. Objective: The aim of this work was to implement three different methods for the detection of apoptosis, using three canine tissue samples, consisting of breast cancer - carcinoma in situ, thymus and plasmacytoma; and a sample of rabbit tissues - thymus. Key words: Rabbit, thymus, immunohistochemistry, apoptosis, TUNEL, Bcl-2, Bax. Methods: Immunohistochemistry was performed, using pro- and antiapoptotic proteins, respectively, Bax and Bcl2 (1: 100; Santa Cruz, Biotechnology) and the TUNEL method (1: 2,5; In situ Cell Death Kit, Roche). Results Canine plasmacytoma revealed moderate positive reaction with all methods. Canine carcinoma in situ showed moderate positive reaction with pro-apoptotic antibodies and more intense with anti-apoptotic antibody. Dog’s thymus showed moderate positive reaction in cortical thymocytes with pro-apoptotic antibodies and weak in the medullary thymocytes. With the anti-apoptotic antibody, medullary thymocytes showed weak reaction and negativity in the cortex. Identical results were obtained in rabbit’s thymus, but with stronger intensity. Conclusions The rabbit thymus showed the most specific reaction of the tissues studied, by which the authors recommended it as a viable positive control for apoptosis studies.
- A rare case of retrobulbar neoplasia.Publication . Vala, Helena; Mega, A.; Santos, C.; Cruz, R.; Nóbrega, C.; Mesquita, JR; Esteves, F.; Vieira, F.; Ferraz, A.Introduction Neoplasms involving the optic nerve are rare. Intraorbital meningiomas, the most common tumour of the optic nerve, represent only 3% of all meningiomas in dogs, so few data exists to predict its symptoms and biologic behaviour. Objectives The authors describe and submit for discussion, a rare case of retrobulbar meningioma, in particular for assessment of histological grade and prognosis. Medical History A 10 year old Labrador Retriever male dog was presented for complaints of swelling and purulent discharge of the right eye. The animal had exophthalmos, protrusion of the third eyelid, chemosis, deep corneal ulceration and no pupillary light reflex. Exophthalmos due to a retrobulbar mass was diagnosed after physical, ophthalmic and ultrasound examination. Material and Methods The sample was fixed in 10 % buffered formalin solution, processed for routine histopathological diagnosis and a standard Streptavidin-Biotin Complex technique for immunohistochemical evaluation was also performed. Results Macroscopic examination revealed a conic mass, located in the retrobulbar portion of the optic nerve, adjacent to the posterior aspect of the globe with homogeneous, lobulated and whitish appearance and firm consistency. Microscopic examination revealed spindloid cells, with round-to-oval, finely stippled nuclei, small or indistinct nucleoli, moderate amount of eosinophilic cytoplasm, arranged in concentric whorls around capillaries, separated by interlacing fascicles, with small amount of well vascularized, collagenous stroma. Conclusion The authors suggested the diagnosis of transitional meningioma, based on the histopathological diagnosis and immunohistochemistry results.
- The importance of oat cells in the diagnosis of Mannheimia haemolyticaPublication . Vala, Helena; Themudo, D.; Santos, C.; Mega, A.; Esteves, F.; Cruz, R.; Mesquita, JR.; Nóbrega, C.Introduction Ovine respiratory disease is frequently associated to high economic losses. It can be caused by several aetiological agents, difficulting the diagnosis and the implementation of effective therapeutic measures. The pathologist has a difficult, but very important role, in the diagnostic procedure, based on standard histomorphological classification of lung injury. Objectives The authors describe and submit for discussion a case of hyperacute pneumonia with high mortality, associated with abrupt climate changes. Medical History High mortality rate, affecting young lambs. At necropsy, dark and firm lungs, with hepatisation were observed, without other significant macroscopic lesions. Material and Methods Lung samples were fixed in 10 % buffered formalin solution and 3 μm thick sections were stained for routine histopathological diagnosis with Haematoxylin and Eosin. Results and discussion Macroscopic examination revealed acute congestion and haemorrhage, involving pleura. The severe pulmonary haemorrhage and congestion and the absence of cranioventral fibrinonecrotizing bronchopneumonia and fibrinous pleuritis, led to consider other causes namely pneumotoxicosis but no Pasteurella. Elongated cells with basophilic spindle-shaped nuclei, in alveoli were also seen. The oat cells, probably caused by leukotoxin from Mannheimia haemolytica, an opportunistic pathogen member of the normal bacterial flora of the nasopharynx and tonsils of ruminants, were crucial to the diagnosis of the present case of hyperacute pneumonia, despite the absence of fibrin. Conclusion The presence of characteristic oat cells contributed to the diagnosis of Mannheimia haemolytica, however microbiological tests are still needed to make a definitive diagnosis.