Browsing by Author "Mega, C."
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- Age influence in BBN induced urothelial lesions in ICR male micePublication . Vasconcelos-Nóbrega, C.; Mega, C.; Arantes, R.; Talhada, D.; Teixeira-Guedes, C.; Faustino-Rocha, A.; Vala, Helena; Oliveira, P. A.
- Biochemical and histological effects of sitagliptin on Zucker Diabetic Fatty rat pancreasPublication . Mega, C.; Vala, Helena; Teixeira de Lemos, E.; Fernandes, R.; Oliveira, J.; Ferreira, L.; Teixeira, F.; Reis, F.Background: Inhibition of dipeptidyl peptidase-4 (DPP-4) activity by sitagliptin has been shown to improve glycemic control in patients with type 2 diabetes Mellitus (T2DM) by prolonging the actions of incretin hormones, but the really impact of low-dose sitagliptin treatment on pancreas lesions is almost unknown. This study aimed to evaluate the effects of sitagliptin on biochemical and histological (pancreas) parameters of Zucker Diabetic Fatty (ZDF, fa/fa) rats, an animal model of T2DM. Methods: Diabetic (fa/fa) ZDF male rats were treated with vehicle or sitagliptin (10 mg/kg BW/day) during 6 weeks (n=8 each). The following parameters were assessed: serum glycaemia, HbA1c, insulin and lipid profile; serum and pancreas oxidative stress (MDA) and endocrine and exocrine pancreas histology, estimating and rating inflammatory infiltrate, fibrosis, vacuolization and congestion in a semiquantitative score ranging from 0 (minimal) to 3 (severe and extensive damage). Results: Sitagliptin in diabetic ZDF rats promoted beneficial effects on dysglycaemia, dyslipidaemia, inflammatory profile and pancreatic oxidative stress. Endocrine and exocrine pancreas presented a reduction/amelioration of fibrosis severity, inflammatory infiltrate, intra-islet vacuolation, and congestion vs the vehicle-treated diabetic rats. Conclusions: The favourable biochemical profile promoted by sitagliptin in the diabetic rats, together with a protection against endocrine and exocrine pancreas lesions, might represent a further advantage of low doses of sitagliptin in the management of T2DM.
- A case of biliary cystadenoma in a geriatric cat.Publication . Vala, Helena; Nóbrega, C.; Ribeiro, A.; Mega, C.; Oliveira, A. L.; Santos, C.; Coelho, C.; Esteves, F.; Cruz, R.; Mesquita, J. R.A 9–year-old male European cat was referred for clinical examination with a history of anorexia, apathy and mild dehydration. Neurological exam revealed anisocoria and decreased pupillary reflex. Ultrasound examination of the abdomen suggested the presence of a mesenteric mass and several areas of renal and hepatic lesions. Renomegaly was also observed. Samples of organs were submitted to the pathology service of the Superior Agrarian School of Viseu. Macroscopic exam of the liver showed several prominent whitish areas that, on cut section, revealed multilocular cystic appearance with greenish colour in some of them. The mesenteric mass, of friable consistency, showed 5,5 x4,4x3,5 cm On cut section this mass revealed whitish areas of soft consistency that alternated with hemorrhagic areas. The kidneys showed an white, irregular surface, and also in one of them a corical prominent nodule was seen. Several sections were processed for routine histopathological diagnosis. Microscopic exam revealed that the mesenteric mass corresponded to a tumour of lymphoid cells. Cells were large, with scanty cytoplasm, euchromatic round nucleus with prominent central nucleoli, high mitotic count and moderate pleomorphism invading surrounding adipose tissue. The same type of cells was observed in the liver and kidneys. Based on these results, a lymphoma with renal and hepatic metastases was diagnosed in the mesenteric mass. Concomitantly, microscopic examination of the liver showed hepatocyte vacuolation and trabecular disorganization, with multiple cystic cavities lined by an epithelium of cubic or squamous type, showing fine fibrovascular tissue stroma. The cuboidal epithelial cells presented a moderate amount of pale eosinophilic cytoplasm, round or oval nucleus, vesicular, oriented centrally and with small or inapparent nucleoli. Based on these results, the diagnosis of neoplasia derived from biliary epithelium, was established. The differential diagnosis to be considered on this case were colangioma and biliary cystadenoma. The definitive diagnosis of biliary cystadenoma was established, based on the presence of multiple cystic cavities, disseminated by the hepatic parenchyma. According to previous statements, it was concluded that in spite of its rare occurrence, this is a case of biliary cystadenoma.
- Diabetic nephropathy amelioration by a low-dose sitagliptin in an animal model of type 2 diabetes (Zucker Diabetic Fatty rat)Publication . Mega, C.; Teixeira de Lemos, E.; Vala, Helena; Fernandes, R.; Oliveira, J.; Mascarenhas-Melo, F.; Teixeira, F.; Reis, F.This study was performed to assess the effect of chronic low-dose sitagliptin, a dipeptidyl peptidase 4 inhibitor, on metabolic profile and on renal lesions aggravation in a rat model of type-2 diabetic nephropathy, the Zucker Diabetic Fatty (ZDF) rat. Diabetic and obese ZDF (fa/fa) rats and their controls ZDF (+/+) were treated for 6 weeks with vehicle (control) or sitagliptin (10 mg/kg/bw). Blood/serum glucose, HbA1c, insulin, Total-c, TGs, urea and creatinine were assessed, as well as kidney glomerular and tubulointerstitial lesions (interstitial fibrosis/tubular atrophy), using a semi-quantitative rating from 0 (absent/normal) to 3 (severe and extensive damage). Vascular lesions were scored from 0-2. Sitagliptin in the diabetic rats promoted an amelioration of glycemia, HbA1c, Total-c and TGs, accompanied by a partial prevention of insulinopenia. Furthermore, together with urea increment prevention, renal lesions were ameliorated in the diabetic rats, including glomerular, tubulointerstitial and vascular lesions, accompanied by reduced lipid peroxidation. In conclusion, chronic low-dose sitagliptin treatment was able to ameliorate diabetic nephropathy, which might represent a key step forward in the management of T2DM and this serious complication.
- Intoxicações nos animais de companhiaPublication . Mota, A.; Mega, C.; Mesquita, J.; Esteves, F.; Cruz, R.; Oliveira, A. L.; Santos, C.; Coelho, C.; Pires, J.; Pires, P.; Silva, V.; Vala, Helena; Nóbrega, C.Os animais de companhia são expostos, muito frequentemente, a produtos tóxicos. Estes são os agentes que provocam envenenamento e podem ser colocados em contacto com o animal de forma acidental ou mesmo propositadamente. A maioria das intoxicações nas espécies canina e felina acontecem por falta de informação dos proprietários, pelo que devem ser aplicadas estratégias educacionais de forma a evitar estas situações. Nestas mesmas estratégias devem ser fornecidas informações sobre os tóxicos mais comuns, bem como sobre os primeiros socorros que devem ser prestados. O Enfermeiro Veterinário possui um papel fundamental, pois pode fornecer essa mesma informação. Para isso, é necessário um conhecimento básico do metabolismo dos venenos, do diagnóstico e da terapêutica para cada tipo de intoxicação.
- Occurrence of Kimmelstiel-Wilson like lesions in the absence of diabetic nephropathy in dogs, may provide a natural model for further research in the corresponding human formPublication . Mega, C.; Mesquita, J.; Nóbrega, C.; Cruz, R.; Esteves, F.; Santos, C.; Lemos, C.; Reis, F.; Vala, HelenaBackground: Nodular glomerulosclerosis occurring in non-diabetic patients is an unexplained renal condition that resembles Kimmelstiel-Wilson lesions (K-W), associated almost exclusively with diabetic nephropathy. This study aimed to assess the presence of nodular glomerulosclerosis in dogs with non-diabetic chronic kidney disease (CKD) and evaluate similarities with human condition, and thus, establish the dog as a natural disease model for further studies. Methods: Kidneys from dogs (n=27) with non-diabetic CKD were evaluated for the presence of nodular glomerulosclerosis. Samples were stained with haematoxylin-eosin and periodic acid of Schiff. Lesions were classified as absent or present, the later, classified as non-convincing and convincing K-W like lesions. Results: Nodular glomerulosclerosis was present in 66.66% of evaluated cases (n=18), of which, 38.88% (n=7) were convincing K-W like lesions and the remaining 61.11% (n=11), although similar, didn’t exhibit typical microscopic characteristics and were classified as non-convincing. Fibrosis was positively associated to diagnosis of K-W lesions (OR=6; p<0.05). Conclusion: As in man, Kimmelstiel-Wilson like lesions may also occur in dogs in the absence of diabetic nephropathy and reveal similar microscopic aspects to the description related in humans and, that some factors, others than hyperglycaemia, may be responsible for the appearance of these lesions. Thus, dogs may provide a model of natural disease for further elucidation.
- Pancreatic lesions and metabolic aggravation are prevented by low doses of sitagliptin in a rat model of type 2 diabetesPublication . Mega, C.; Vala, Helena; Oliveira, J.; Fernandes, R.; Mascarenhas-Melo, F.; Parada, B.; Pinto, R.; Teixeira, F.; Teixeira de Lemos, E.; Reis, F.Introduction: The management of type 2 diabetes is designed to reduce disease-related complications and improve long-term outcomes. Inhibition of dipeptidyl peptidase-4 (DPP-4) activity by sitagliptin has been shown to improve glycaemic control in patients with type 2 diabetes Mellitus (T2DM) by prolonging the actions of incretin hormones, but the real impact of low-dose sitagliptin treatment on cardiometabolic risk factors and pancreatic lesions is almost unknown. This study aimed to evaluate the effects of low doses of sitagliptin on cardiovascular risk factors and histological pancreas parameters in Zucker Diabetic Fatty rats (ZDF (fa/fa)) an animal model of T2DM. Materials and Methods: Twenty weeks old diabetic obese (fa/fa) ZDF male rats were treated with vehicle or sitagliptin (10 mg/kg BW/day) during 6 weeks (n=8 each). The following parameters were assessed: glycaemia, HbA1c, insulin, lipidic profile; blood pressure. Specimens for pancreatic histopathology were stained with haematoxylin-eosin and periodic-acid-Shiff, examined by light microscopy. Endocrine and exocrine pancreas was evaluated semiquantitatively concerning inflammatory infiltrate, fibrosis, vacuolization and congestion, and scored from 0 (absent) to 3 (severe and extensive damage). Results: Sitagliptin in diabetic obese ZDF rats promoted a positive effect on dysglycaemia, dyslipidaemia and prevented the increase of blood pressure. Endocrine and exocrine pancreas presented a reduction/amelioration of fibrosis severity, inflammatory infiltrate, intra-islet vacuolation, and congestion vs the vehicle-treated diabetic rats. Conclusion: Simultaneous improvement of a sustainable glycaemic profile and of pancreatic histopathological lesions supports the favorable cardiovascular risk profile and may prove beneficial in decreasing long-term complications of T2DM.
- Pancreatic protection afforded by sitagliptin in a rat model of type 2 diabetes: putative mechanismsPublication . Mega, C.; Vala, Helena; Oliveira, J.; Teixeira, F.; Fernandes, R.; Teixeira de Lemos, E.; Reis, F.
- Processamento Histológico dos Tecidos OcularesPublication . Mega, C.; Nóbrega, C.; Mesquita, J. R.; Oliveira, A.; Santos, C.; Esteves, F.; Cruz, R.; Vala, HelenaThe growing interest in veterinary ophthalmology and the development of new techniques for eye examination, such as ultrasound, fluorescein angiography, and vitreous fluorometry, optical coherence tomography (OCT), which allow an almost complete view of all eye layers, could lead us to think that histopathology would be relegated to the background. The reality shows the exact opposite, because although diagnoses obtained by the new technology can reveal topographic and vascular features, types of tissue affected and even the layer of tissue affected by the injury, it can not, however, reveal the cellular changes underlying the lesion and characterize it from a histological point of view. In addition, the development of clinical diagnosis associated with modern technology results in an increased number of specimens submitted to laboratory due to the possibility of detection of lesions that previously went unnoticed. Therefore, and despite all the technological evolution, histopathology remains the source of definitive diagnosis in many diseases and is often the only way to clarify the etiology, severity, prognosis and subsequent therapeutic decisions. This makes it important to review the current histologic processing of these specific tissues. Eye tissues are obtained by surgical excision of the eyeball with the adjacent orbital tissues, as in exenteration and transpalpebral or, without the adjacent orbital tissues, in situations of transconjunctival enucleations, evisceration, incisional or excisional biopsies, exfoliative preparations and aspirates with fine needle. The processing techniques vary accordingly with the method of sample acquisition, as fixation, removal of exenterated tissues and the delineation of lesion margins. The options for eye sectioning are performed according to the presence of the macula, as in primates and birds, or absence of the macula, as in other mammals. Several methods of fixation using formaldehyde, glutaraldehyde, Bouin’s fluid, triple fixation, Zenker’s fluid and Davidson’s fixative, will be presented. The various staining methods used, as in routine staining with hematoxylin-eosin and the histochemical methods such as PAS, Congo red, Masson-Fontana, among others and according to the target tissue. The appropriateness of each method to the observational means, like light microscopy, electron microscopy and immunohistochemistry. Their advantages and disadvantages will be referred
- Progression of renal disease in the Zucker Diabetic Fatty rat, an experimental model of Type2 DiabetesPublication . Mega, C.; Vala, Helena; Oliveira, J.; Fernandes, R.; Mascarenhas-Melo, F.; Parada, B.; Pinto, R.; Teixeira, F.; Reis, F.; Teixeira de Lemos, E.