Browsing by Author "Mesquita, JR."
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- Characterization of histopathologic lesions in gastroenteritis associated to norovirus in a model of studyPublication . Vala, Helena; Mesquita, JR.; Nascimento, M. S. J.Background: Human noroviruses are the major cause of nonbacterial epidemic gastroenteritis worldwide. Although noroviruses have been absent from the list of gastrointestinal infectious agents in dogs, recently several studies emphasized their role in the aetiology of gastroenteritis, suggesting the possibility of a novel model for human infection. The aim of this study was to evaluate the histopathological lesions in gastroenteritis, associated to canine norovirus, in order to contribute to the knowledge of its pathogenic features and the role of apoptotic events in the noroviruses pathogenesis. Material and methods: Samples of small intestine were collected from 2 adult dogs (2-year-old cross-bred and a 6 year-old cocker spaniel) housed in a kennel where CaNoV had been diagnosed. Samples of small intestine were collected and fixed (10% neutral buffered formalin) for a maximum of 48 hours, dehydrated (graded ethanol series) and embedded in paraffin wax. Apoptosis studies combined the immunohistochemical detection of cytochrome c (anti-cytochrome C sc-8385 antibody, Santa Cruz Biotechnology) and the DNA fragmentation by TUNEL assay (In Situ Cell Death Detection Kit, Roche, Germany). Samples were examined by light microscopy (Microscope Zeiss Mod. Axioplan 2), by two independent observers. All procedures were performed in accordance with the European Communities Council Directive 86/609/ECC. Results: The microscopic findings revealed severe epithelial detachment, mucosal loss and hypertrophy of all small intestinal layers. Also, an intense mononuclear inflammatory infiltrate within lamina propria of small intestine proximal segments were seen, very similar to IBD lesional pattern. Discussion and Conclusions: Canine inflammatory bowel disease (IBD) is a heterogeneous group of chronic gastrointestinal disorders with unknown aetiology, immunologically-mediated, similar to human IBD. With this study it is tempting to hypothesize that canine norovirus could be significantly evolved in the complex aetiopathogenesis of IBD, identically in human Crohn disease - an example of human IBD, which could highlight the relevance of norovirus, in its role of in the aetiopathogenesis of this chronic condition.
- Histological distribution of normal pigment in silkie fowlsPublication . Vala, Helena; Esteves, Fernando; Cruz, R.; Mesquita, JR.; Themudo, D.; Nóbrega, Carmen; Santos, C.; Mega, CristinaIntroduction In most homeothermic vertebrates, pigment cells are confined to the skin, since melanoblast is the only neural crest lineage that can migrate dorsolaterally, between the ectoderm into the derm. Silkie fowl, is a naturally occurring chicken mutant from common chicken, in which pigment cells occupy most connective tissues, given them a dramatic blue-black pigmentation. This occurs because melanoblasts continue to migrate, extensively dorsolateral and ventrally, since the natural tissue barriers, which normally restrain melanoblast migration, are not present in the Silkie fowl. Objectives The authors document, using macro and microscopic figures, the normal distribution of the melanic pigment in the Silkie fowl tissues. Material and Methods 2 adult Silkie fowls were necropsied and samples fixed in 10% neutral-buffered formalin and processed for routine histopathological diagnosis. Results and discussion The distribution of the melanin pigment was observed in the periosteum, perichondrium, connective tissues of adventitia and serosae from several internal organs, as well as in the myocardium, perimysium and endomysium. Conclusion The knowledge of the normal distribution of the melanic pigment in the Silkie fowl tissues allow a better understanding of the histopathological conditions affecting this particular breed.
- Rabbit haemorrhagic disease (RHD) – a new variant?Publication . Vala, Helena; Coelho, C.; Nóbrega, C.; Mesquita, JR.; Oliveira, J.Background: Rabbit haemorrhagic disease (RHD) is an acute fatal disease of domestic and wild European rabbits caused by a RNA virus (genus Lagovirus, family Caliciviridae). Prior to 1984, healthy rabbits in European regions had RHDV-specific antibodies and their infection with benign rabbit caliciviruses conferred them a low degree of cross-protective immunity against RHD, determining less severe clinical courses. Vaccination allowed to control the disease in the rabbit industry, but RHD still threatens non-vaccinated wild populations. A new variant of this disease is being described since 2010 in Iberian Peninsula. It affects mainly young rabbits that exhibit haemorrhages in heart, trachea, thymus, lungs, liver, kidneys and gut, as well as DIC, jaundice, splenomegaly and catarrhal enteritis. Objectives: To describe a case of high mortality rate on a rabbitry, mostly in young rabbits, with typical lesions of RHD. Methods: Samples from domestic vaccinated and non vaccinated rabbits which died suddenly were taken and fixed in 10% neutral-buffered formalin for 48 hours and embedded in paraffin. 3µm sections were stained for routine histopathological diagnosis (H&E) and examined by light microscopy. Results: Main macroscopic lesions observed: opisthotonos, oedema and pulmonary congestion, severe jaundice, splenomegaly, gastric punctiform ulcers, bilateral renal congestion and thymic petechiae, Conclusions: Macroscopic lesions in infected young’s, consistent with RHD infection usually observed only in adult rabbits, and the presence of lesions mostly associated to the new variant of RHD (DIC, jaundice, splenomegaly, catarrhal enteritis), led us to consider the presence of the new variant of RHD in Portugal, although further studies are needed.
- 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.