Browsing by Author "Teixeira de Lemos, E."
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- 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.
- 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.
- 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.
- 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.
- Presence of Kimmelstiel-Wilson like lesions in canine renal faillurePublication . Vala, Helena; Mega, A. C.; Mesquita, J.; Nóbrega, C.; Cruz, R.; Esteves, F.; Ortiz, A. L.; Santos, C.; Teixeira de Lemos, E.; Reis, F.Background: Nodular increases in mesangial matrix is the definition of Kimmelstiel-Wilson (K-W) lesions. In man, focal mesangiolyses and K-W nodules were positively associated with diabetes, proteinuria and hyalinization of afferent and efferent arterioles. Although, nodular sclerotic lesions may also occur in the absence of diabetic nephropathy and are clinically related to hypertension, smoking, hypercholesterolemia, among others. This study aimed to assess the presence of nodular glomerulosclerosis in dogs in non-diabetic chronic kidney disease. Materials and Methods A retrospective study including dogs with non-diabetic chronic kidney disease (n=27) was performed. Samples were stained with haematoxylin-eosin and periodic acid of Schiff and classified according to Maxie (2007). Lesions were classified as absent or present and the later, as non-convincing and convincing K-W like lesions. Univariate logistic regression models were performed to measure the association between a positive histological diagnosis of K-W lesions and the accessed histological features (variables membranes, inflammation, atrophy and fibrosis) by using statistical software R with Epicalc package. Results Nodular glomerulosclerosis was present in 66.66% of evaluated cases (n=18) of which, 38.88% (n=7) were classified as convincing and 61.11% (n=11) as non-convincing. The convincing K-W like lesions observed, revealed similar microscopic aspects to the descriptions in literature related to man. The presence of fibrosis was positively associated to the diagnosis of K-W lesions (OR=6; p<0.05). The remaining variables were not statistically associated (p>0.05). Conclusion Presence of K-W like lesions, in dogs with renal failure exposed a possible association with end-stage renal disease. Therefore, the diagnosis of K-W like lesions could be helpful to specify and define renal biopsies.
- Presence of Kimmelstiel-Wilson like lesions in canine renal faillurePublication . Vala, Helena; Mega, A. C.; Mesquita, J.; Nóbrega, C.; Cruz, R.; Esteves, F; Santos, C.; Teixeira de Lemos, E.; Reis, F.Background: Nodular increases in mesangial matrix is the definition of Kimmelstiel-Wilson (K-W) lesions. In man, focal mesangiolyses and K-W nodules were positively associated with diabetes, proteinuria and hyalinization of afferent and efferent arterioles. Although, nodular sclerotic lesions may also occur in the absence of diabetic nephropathy and are clinically related to hypertension, smoking, hypercholesterolemia, among others. This study aimed to assess the presence of nodular glomerulosclerosis in dogs in non-diabetic chronic kidney disease. Materials and Methods A retrospective study including dogs with non-diabetic chronic kidney disease (n=27) was performed. Samples were stained with haematoxylin-eosin and periodic acid of Schiff and classified according to Maxie (2007). Lesions were classified as absent or present and the later, as non-convincing and convincing K-W like lesions. Univariate logistic regression models were performed to measure the association between a positive histological diagnosis of K-W lesions and the accessed histological features (variables membranes, inflammation, atrophy and fibrosis) by using statistical software R with Epicalc package. Results Nodular glomerulosclerosis was present in 66.66% of evaluated cases (n=18) of which, 38.88% (n=7) were classified as convincing and 61.11% (n=11) as non-convincing. The convincing K-W like lesions observed, revealed similar microscopic aspects to the descriptions in literature related to man. The presence of fibrosis was positively associated to the diagnosis of K-W lesions (OR=6; p<0.05). The remaining variables were not statistically associated (p>0.05). Conclusion Presence of K-W like lesions, in dogs with renal failure exposed a possible association with end-stage renal disease. Therefore, the diagnosis of K-W like lesions could be helpful to specify and define renal biopsies.
- 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.
- Renal structure modification in an animal model of type 2 diabetes with aging: focus on hydronephrosisPublication . Mega, C.; Vala, Helena; Oliveira, J.; Fernandes, R.; Mascarenhas-Melo, F.; Parada, B.; Pinto, R.; Teixeira, F.; Teixeira de Lemos, E.; Reis, F.Background and aims: The Zucker Diabetic Fatty (ZDF-fa/fa) rat is one of the most used models for the study of type 2 diabetes (T2DM). Characterization of renal morphology in this model may provide useful insights into the mechanism of diabetic nephropathy progression. The purpose of the present study was to determine renal morphology, identify and characterize renal dysfunction complications such as hydronephrosis, in Zucker Diabetic fatty (ZDF) rat through T2DM evolution. Material and Methods: Male diabetic obese ZDF (fa/fa) rats were sacrificed at 8, 20 and 26 weeks of age and compared with their lean counterparts ZDF (+/+) with de same age. Biochemistry in serum for metabolic assessment was also performed. Kidney slices stained with hematoxylin-eosin and periodic acid-Schiff were evaluated. A semiquantitative rating was assigned for hydronephrosis and scored from 0 (normal) to 3 (severe), based on conformational aspects of the papilla and calyx and cortex compression. Results: A striking progression in the severity of hydronephrosis was observed. All end-disease state rats, 26 weeks of age, showed hydronephrosis, which was more severe in the diabetic rats (scoring: 2, 3) when compared to lean controls (scoring 1). No significant cortical atrophy was found. These abnormalities accompanied aggravation in diabetic desmetabolism. Conclusions: The present study indicates that ZDF rats present nephropathy with hydronephrosis. Lesions are age-related and aggravated by diabetic desmetabolism but don’t hinder morphological evaluation. Therefore the ZDF rat might represent a useful model for the preclinical study of therapeutic interventions in diabetic nephropathy.
- Sitagliptin delays progression of renal lesions in a rodent model of type 2 diabetesPublication . Cristina, M.; Vala, Helena; Oliveira, J.; Fernandes, R.; Mascarenhas-Melo, F.; Parada, B.; Pinto, R.; Teixeira, F.; Reis, F.; Teixeira de Lemos, E.