Browsing by Author "Mega, Cristina"
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- A 2-Year Longitudinal Seroepidemiological Evaluation of Toxoplasma gondii Antibodies in a Cohort of Autochthonous Sheep from Central PortugalPublication . Almeida, Daniela; Quirino, João; Barradas, Patrícia Ferreira; da Silva, Priscilla Gomes; Pereira, Maria; Cruz, Rita; Santos, Carla; Mega, Cristina; Esteves, Fernando; Nóbrega, Carmen; Vala, Helena; Gärtner, Fátima; Amorim, Irina; Mesquita, João R.Background: Toxoplasma gondii is an important zoonosis and one of the major causes of abortion in sheep worldwide. (2) Methods: We performed a 2-year longitudinal serological antiT. gondii IgG screening on a cohort of a spatially confined population of a Portuguese autochthonous sheep breed in central Portugal. (3) Results: From the screening of the 2015 and 2016 sera, an increase of seroprevalence was observed (57.7% (95% CI: 49.9–65.3%) versus 69.1% (95% CI: 61.5–75.9), from 2015 and 2016, respectively) (p = 0.031). (4) Conclusions The present study is the first to provide prospective data on the anti-T. gondii serological status of a sheep cohort in Portugal, showing an increase in the occurrence of T. gondii. There is a need to provide a clearer understanding of T. gondii epidemiology in Portugal, ideally by implementing monitoring programs on sentinel herds, not only due to the high impact of T. gondii on animal health but also for it being a zoonosis.
- Bioética e experimentação animalPublication . Nóbrega, Carmen; Oliveira, P. A.; Mesquita, João; Santos, C.; Arantes, R.; Themudo, D.; Esteves, Fernando; Cruz, Rita; Mega, Cristina; Vala, Helena- Introdução: O contributo da experimentação animal para a ciência é inegável. Dificilmente os meios médicos e profiláticos teriam atingido o presente estado de evolução sem a sua contribuição. O objectivo deste trabalho é a apresentação do conceito de experimentação animal, como uma prática válida e eticamente correta, desde que devidamente planeada e executada. - Estado da Arte: O recurso a animais vivos em investigação, tem desempenhado um papel importante no avanço científico, particularmente na área da saúde. Este facto dá origem a um dilema ético: se por um lado a maior parte dos animais utilizados são seres sencientes, por outro lado, a investigação pode ser de vital importância para a prevenção, cura ou melhoria significativa de doenças em humanos. Não sendo um tema consensual, é geralmente alvo de intenso debate. Opositores a qualquer tipo de investigação com recurso a animais, afirmam que a experimentação animal é cruel e desnecessária porque os animais não existem para serem usados segundo o nosso critério. No entanto, a generalidade da sociedade aceita que os animais possam ser utilizados em experimentação mas não a qualquer preço. Nos últimos anos, têm ocorrido progressos na criação de alternativas à experimentação animal, nomeadamente as culturas celulares, de tecidos e órgãos, fazendo com que, em certas situações, os animais possam já ser substituídos por alternativas eticamente mais aceitáveis, não podem, contudo, ser inteiramente eliminados da investigação. - Novas perspetivas/diretrizes Uma investigação ética e cientificamente válida com aplicabilidade na saúde humana, exige a seleção de modelos adequados para a acção estudada e o cumprimento do princípio dos 3Rs: Replace; Reduce; Refine. A estes, deve juntar-se ainda o R da responsabilidade, que deve prevalecer desde o delineamento da experimentação e acompanhar o decurso dos trabalhos experimentais. - Implicações teóricas e práticas Pesando os prós e contras, os benefícios da experimentação animal pesam mais no que se refere ao impacto na melhoria da saúde humana. Se esta prática fosse abandonada, certamente existiriam severas consequências a nível da investigação e da saúde pública.
- Carcinogénese Experimental da Bexiga em MurganhosPublication . Nóbrega, Carmen; Vala, Helena; Mesquita, João; Santos, C.; Themudo, D.; Oliveira, P. A.; Esteves, Fernando; Cruz, Rita; Mega, Cristina; Arantes, R.; PA., OliveiraIntrodução: A oncologia experimental é uma ciência em crescente evolução, que tem permitido estudar os mecanismos biopatológicos associados ao crescimento, invasão e metastização dos tumores, bem como a investigação de novas moléculas, eventuais novos agentes profilácticos, terapêuticos ou paliativos. O objetivo deste trabalho consiste na apresentação de um projeto de investigação em que se promoveu a carcinogénese experimental da bexiga em murganhos, para a posterior realização testes farmacológicos. Estado da Arte: O cancro da bexiga é o 7º tumor mais comum no homem e o 2º do trato urogenital, encontrando-se descrita predisposição sexual para o sexo masculino (4:1). Histologicamente, a maioria dos tumores de bexiga são superficiais, sendo o carcinoma invasivo menos frequente. No entanto, este último assume grande importância clínica, dado o difícil tratamento, a elevada possibilidade de metastização e o prognóstico reservado. São vários os modelos animais que podem ser utilizados no estudo dos tumores bexiga. O modelo animal para o carcinoma invasivo da bexiga consiste na indução pela administração na água de bebida da N-butil-N-(4-hidroxibutil)nitrosamina (BBN) a murganhos. Métodos: Foram utilizados murganhos macho da estirpe ICR, divididos em dois grupos: grupo controlo e experimental, que foi submetido à acção da BBN (0,05%), durante 12 semanas. Os animais foram distribuídos por gaiolas adequadas em tamanho, com água à disposição, alimentação ad libitum e enriquecimento ambiental. Todos os animais foram sacrificados no final do trabalho experimental e submetidos a necrópsia. Resultados: A incidência de tumores induzidos pela BBN, em roedores, atingiu os 100%. Foram também observadas outras lesões, nomeadamente metaplasia epidermoide, hiperplasia simples, hiperplasia nodular, displasia e hiperplasia papilar. Conclusões: As lesões quimicamente induzidas em roedores pela BBN assemelharam-se grandemente às observadas em humanos, facto que permitiu caraterizar este como um bom modelo para o estudo das neoplasias da bexiga.
- A case of giant cell tumourPublication . Vala, Helena; Andrade, Luís; Nóbrega, Carmen; Santos, Carla; Cruz, Rita; Mega, Cristina; Esteves, Fernando; Gomes, A.; Mesquita, JoãoMalignant fibrous histiocytoma refers to a group of soft tissue tumours that represents a diagnostic challenge which must be based in the predominant cellular type present. The authors describe an unusual case of tumour in which the presence of giant cells was the distinctive feature. A 7 year old Cocker Spaniel male dog was presented with a subcutaneous nodule in the labial commissure, measuring 1.5 cm in diameter. Sample was fixed in 10 % buffered formalin solution, embedded in paraffin wax and 3 μm thick sections were stained for routine histopathological diagnosis with Haematoxylin and Eosin. A standard Streptavidin-Biotin Complex technique for immunohistochemical evaluation was also performed. Macroscopic examination revealed dark brown, slightly lobed tissues, alternating with whitish tissues, both with moderate consistency on the cut surface. Microscopic examination revealed ulceration and necrosis of the epidermis, under which a high cellular population of undifferentiated cells was observed. These cells population exhibited oval, normo or eucromatic nucleus, with notorious nucleolus and moderate cytoplasm that, resembled fusiform fenotype, intermixed with blood vessels and multinucleated giant cells, as well as intense immunoreactivity for vimentin. The authors suggest the diagnosis of malignant fibrous histiocytoma of giant cell subtype, based on the multinucleated giant cells predominance and submit it to the discussion, particularly for histological grade assessment and prognosis, since there is still some discrepancy in the literature.
- A case of vascular tumour mimicking lymphangiomaPublication . Vala, Helena; Mega, Cristina; Santos, C.; Cruz, Rita; Santos, M.; Esteves, Fernando; Nóbrega, Carmen; Mesquita, JoãoIntroduction Sarcomas, particularly vascular tumours, can mimic other neoplastic conditions or even inflammatory diseases. Objectives The authors describe an unusual case of vascular tumour, histologically overlapping with benign lymphangioma and liposarcoma. Medical History A 8 year old Shar Pei male dog was presented with a subcutaneous nodule in the chest, measuring 3x2 cm. Material and Methods The sample was fixed in 10 % buffered formalin solution and processed for routine histopathological diagnosis with Haematoxylin and Eosin. A standard Streptavidin-Biotin Complex technique for immunohistochemical evaluation was also performed, using a Polyclonal Rabbit Anti-Human Von Willebrand Factor. Results Macroscopic examination revealed a well circumscribed nodule with homogeneous and brownish appearance and moderate consistency on a cut surface. Microscopic examination revealed clefts and variably-sized vascular spaces, lined by a single layer of spindle cells, with round-to-oval nuclei, small or indistinct nucleoli, small amount of eosinophilic cytoplasm, with endothelial appearance – areas like hemangiosarcoma, interspersed with areas, where these cells appeared to grow directly on thick bundles of dermal collagen, occasionally with erythrocytes – areas like lymphangioma. The stroma was also interspersed with vacuolar cells – areas like liposarcoma. No mitotic figures were seen, however, the presence of very rich cellular areas, with more prominent cells revealing pleomorphism and anisocariosis, were more favour to malignancy Conclusion The authors suggested the diagnosis of vascular neoplasia with unusual features, based on the histopathological diagnosis and immunohistochemistry results, and submit to the discussion, especially for assessment of histological grade and prognosis.
- Crimean-Congo hemorrhagic fever virus circulating among sheep of Portugal: a nationwide serosurvey assessmentPublication . Mesquita, João; Cruz, Rita; Esteves, Fernando; Santos, Carla; Pousa, Humberto; Coelho, Catarina; Mega, Cristina; Nóbrega, Carmen; Vala, Helena; Peyrefitte, Christophe Nicolas; Nascimento, Maria São José; Barradas, Patrícia FerreiraCrimean-Congo hemorrhagic fever virus (CCHFV) is a widespread zoonotic pathogen that can cause mild to severe hemorrhagic disease in humans. CCHFV may be transmitted through direct contact with tissue or blood of viremic animals; however, the primary transmission route is through infected tick bites. CCHFV RNA has been detected in ticks feeding on domestic and wild animals in western Spain, suggesting an established circulation of CCHFV in Western Europe. Ruminants have been recognized as important CCHFV reservoirs and have been linked to human cases in endemic regions. Given the emergence of CCHF in neighboring Spain, and a report of two CCHFV seropositive humans in southern Portugal in 1985, we investigated the potential circulation of this virus in the country by performing a nationwide anti-CCHFV IgG serosurvey in sentinel sheep of Portugal. Sera (n = 459) randomly selected from widely distributed farms (n = 20) of Portugal were tested using a commercial double-antigen enzyme-linked immunosorbent assay, yielding an overall seroprevalence of 0.4% (95% confidence interval [CI] 0.04-1.56%). Positive sheep were from the southern region of Portugal (Alentejo region), which raise the seroprevalence of this region to 0.74% (95% CI 0.09-2.66%). This is the first study reporting the presence of CCHFV antibodies in sheep of Portugal, thus suggesting a geographical expansion of CCHFV to this country. It seems likely that CCHFV may exist focally in southern Portugal.
- Effects of Sitagliptin Treatment on Dysmetabolism, Inflammation, and Oxidative Stress in an Animal Model of Type 2 Diabetes (ZDF Rat)Publication . Ferreira, Liliana; Teixeira-de-Lemos, Edite; Pinto, Filipa; Parada, Belmiro; Mega, Cristina; Vala, Helena; Pinto, Rui; Garrido, Patrícia; Sereno, José; Fernandes, Rosa; Santos, Paulo; Velada, Isabel; Melo, Andreia; Nunes, Sara; Teixeira, Frederico; Reis, FlávioThe purpose of this paper is to evaluate the chronic effect of sitagliptin on metabolic profile, inflammation, and redox status in the Zucker Diabetic Fatty (ZDF) rat, an animal model of obese type 2 diabetes. Diabetic and obese ZDF (fa/fa) rats and their controls (ZDF +/+) were treated during 6 weeks with vehicle (control) and sitagliptin (10 mg/kg/bw). Glucose, HbA1c, insulin, Total-c, TGs, IL-1beta, TNF-alpha, CRPhs, and adiponectin were assessed in serum and MDA and TAS in serum, pancreas, and heart. Pancreatic histology was also evaluated. Sitagliptin in diabetic rats promoted a decrease in glucose, HbA1c, Total-c, and TGs accompanied by a partial prevention of insulinopenia, together, with a decrease in CRPhs and IL-1beta. Sitagliptin also showed a positive impact on lipid peroxidation and hypertension prevention. In conclusion, chronic sitagliptin treatment corrected the glycaemic dysmetabolism, hypertriglyceridaemia, inflammation, and hypertension, reduced the severity of the histopathological lesions of pancreatic endocrine and exocrine tissues, together with a favourable redox status, which might be a further advantage in the management of diabetes and its proatherogenic comorbidities.
- Feline injection site sarcomasPublication . Nóbrega, Carmen; Mesquita, João; Cruz, Rita; Coelho, C.; Esteves, Fernando; Mega, Cristina; Santos, C.; Vala, HelenaFeline injection site sarcoma (FISS), formerly known as Vaccine Associated Sarcoma (VAS) is a rare, but life-threatening disease. The incidence estimates have varied from 1 case of FISS per 1,000-10,000 cats vaccinated in North America and between 1 per 5,000-12,500 vaccination visits in United Kingdom. It has been primarily associated with vaccine administration, but several other injectable materials/substances have been implicated as aetiologic agents, namely lufenuron, penicilin, metilprednisolone, meloxicam, non-absorbable suture material and microchip. FISS can have a large latency period (three months-13 years), but eight years old is the average age of onset. They are tumours that arise subcutaneously, reaching a variable number of layers beneath the skin (muscle, bone). They are firm, not painful, solid and variable in size. Clinical assessment and biopsy are the basis for FISS diagnosis. In order to prevent FISS, vaccination should be carefully planned and be provided in easily resectable regions. Hind legs, tail and flanks, are preferable regions for vaccine administration.
- 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.
- Hormones and their Functions in the Dog. From the Cell to Hormone and from Hormone to ActionPublication . Vala, Helena; Mesquita, João; Esteves, Fernando; Cruz, Rita; Mega, Cristina; Nóbrega, CarmenAnimal bodies represent one of the more complex and perfect systems of nature but despite its complexity and functionality, the control of its basic functions is performed by only two systems: the nervous system and the endocrine system. Reproduction, gestation, muscle contraction, nutrient digestion and absorption, hydroelectrolytic balance, haematopoiesis and so many other bodily functions, are directly or indirectly controlled by these systems. In a simplistic way, we can say that the nervous system is responsible for rapid organic activities, while the endocrine system is responsible for a slower, more durable activity, the metabolic functions of the organism. The endocrine system is essential for growth and development, sexual function, reproductive processes and metabolism. In the present work the authors describe the main endocrine glands in the dog, namely anterior and posterior pituitary gland, thyroid, parathyroid, pancreas and adrenal glands, referring their location, macroscopic and histologic features, using original figures. Main endocrine hormones and hormonal functions will also be addressed in a simple, straightforward and original manner, using cutting-edge, innovative schemes that will contribute for an easy and direct understanding of the complex endocrine mechanisms. The endocrine system is often subjected to pathological changes. Improving knowledge in the field of endocrinology will allow for a better clinical approach to animal patients, enhancing, without doubt, the provision of better medical veterinary care and its advancement towards excellence.
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