Percorrer por autor "Reis, Flávio"
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- CHARACTERIZATION OF RENAL (DYS)FUNCTION IN RAT MODELS OF EARLY AND ADVANCED CHRONIC KIDNEY DISEASEPublication . Lousa, Irina; Reis, Flávio; Vieira, Pedro; Vala Correia, Helena Maria; Belo, Luís Filipe Barbosa Amado; Santos-Silva, Alice
- Conversion to sirolimus ameliorates cyclosporine-induced nephropathy in the rat – focus on serum, urine, gene and protein renal expression biomarkersPublication . Sereno, José; Nunes, Sara; Rodrigues-Santos, Paulo; Vala, Helena; Rocha-Pereira, Petronila; Fernandes, João; Santos-Silva, Alice; Teixeira, Frederico; Reis, FlávioProtocols of conversion from cyclosporine A (CsA) to sirolimus (SRL) have been widely used in immunotherapy after transplantation to prevent CsA-induced nephropathy, but the molecular mechanisms underlying these protocols remain nuclear. This study aimed to identify the molecular pathways and putative biomarkers of CsA-to-SRL conversion in a rat model. Four animal groups (𝑛 = 6) were teste during 9 weeks: control, CsA, SRL, and conversion (CsA for 3 weeks followed by SRL for 6 weeks). Classical and emergent serum, urinary, and kidney tissue (gene and protein expression) markers were assessed. Renal lesions were analyzed in hematoxylin and eosin, periodic acid-Schiff, and Masson’s trichrome stains. SRL-treated rats presented proteinuria and NGAL (serum and urinary) as the best markers of renal impairment. Short CsA treatment presented slight or even absent kidney lesions and TGF- β , NF-𝜅β , mTOR, PCNA, TP53, KIM-1, and CTGF as relevant gene and protein changes. Prolonged CsA exposure aggravated renal damage, without clear changes on the traditional markers, but with changes in serums TGF-β and IL-7, TBARs clearance, and kidney TGF- β and mTOR. Conversion to SRL prevented CsA-induced renal damage evolution (absent/mild grade lesions), while NGAL (serum versus urine) seems to be a feasible biomarker of CsA replacement to SRL
- Efeitos de Diferentes Doses de Eritropoietina Recombinante Humana num Modelo Animal de Anemia na Doença Renal CrónicaPublication . Ribeiro, Sandra; Garrido, Patrícia; Fernandes, João; Rocha, Susana; Vala, Helena; Rocha-Pereira, Petronila; Belo, Luís; Reis, Flávio; Santos-Silva, Alice
- 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.
- Exercise training is associated with improved levels of C-reactive protein and adiponectin in ZDF (type 2) diabetic rats.Publication . Teixeira de Lemos, Edite; Reis, Flávio; Baptista, Sofi a; Pinto, Rui; Sepodes, Bruno; Vala, Helena; Rocha-Pereira, P.; Silva, Alice Santos; Teixeira, FredericoChronic low-grade systemic infl ammation is a feature of such chronic diseases as cardiovascular disease and type 2 diabetes (T2D). There is evidence that regular exercise is effective as a treatment in these situations. This study intended to assess the levels of two infl ammatory mediators, C-reactive protein (CRP) and adiponectin, in Zucker Diabetic Fatty (ZDF, fa/fa) rats, an experimental model of T2D, and to determine whether exercise-induced changes in insulin resistance could be explained by modifi cations in these infl ammation markers. Material/Methods: Male ZDF (Gmi fa/fa) rats and their littermates (Gmi +/+), aged 8 weeks, were randomly assigned in two groups: an exercise trained and a sedentary one. Swimming was conducted 1 h/day 3 days/week for 12 weeks. The rats were sacrifi ced 48 h after the last round of exercise. Rats had their body weight, insulin, adiponectin, CRP, as well as glucose, total cholesterol, triglycerides, MDA, and SOD measured and HOMA-IR calculated before and after the 12-week swimming training. Results: In the ZDF (fa/fa) rats underwent swimming exercise, all the metabolic abnormalities were totally or partially prevented ( p<0.001), namely the hyperglycemic, hyperinsulinemic, and dyslipidemic pattern observed in their sedentary counterparts. Furthermore, even without body weight change, a plasma adiponectin increase (28.0%) and a CRP decrease (12.7%) were also observed. Conclusions: A 12-week thrice-weekly swimming training was associated with improved measures of chronic in- fl ammation markers as measured by adiponectin and CRP. Moreover, improvements in insulin sensitivity resulting from swimming exercise appeared to be related to changes in these infl ammatory mediators.
- Impaired renal endothelial nitric oxide synthase and reticulocyte production as modulators of hypertension induced by recombinant human erythropoietin in the ratPublication . Ribeiro, Sandra; Garrido, Patrícia; Fernandes, João; Vala, Helena; Rocha-Pereira, Petronila; Costa, Elísio; Belo, Luís; Reis, Flávio; Santos-Silva, AliceINTRODUCTION AND AIMS: Hypertension is a common side effect of recombinant human erythropoietin (rHuEPO) therapy; however, the exact pathways remain to be elucidated. The discovery of non-hematopoietic actions of rHuEPO increased the number of patients that could putatively benefit from this therapy; however, to achieve those effects higher doses are usually needed, which increase the risk and incidence of adverse events. Our aim was to study the effect of a broad range of rHuEPO doses on hematological and biochemical parameters, blood pressure and renal function and damage in the rat, focusing on endothelial nitric oxide synthase (eNOS) and hypoxia-inducible factors (HIFs). METHODS: Male Wistar rats were divided in 5 groups receiving different doses of rHuEPO (100, 200, 400 and 600 IU/kg body weight (BW)/week) and saline solution (control), during 3 weeks. Blood and 24h urine were collected to perform hematological and biochemical analysis. Blood pressure (BP) was measured by the tail-cuff method. The kidney tissue was collected to mRNA and protein expression assays and to characterize renal lesions. RESULTS: A dose-dependent increase in red blood cells count, hematocrit and hemoglobin levels was found with rHuEPO therapy, in rHuEPO200, rHuEPO400 and rHuEPO600 groups. Increased reticulocyte count was found in the rHuEPO400 and rHuEPO600 groups. BP raised in all groups receiving rHuEPO. The rHuEPO200 and rHuEPO600 groups presented increased kidney protein levels of HIF2α and a reduction in kidney protein levels of eNOS, along with the highest grade of vascular and tubular renal lesions. CONCLUSIONS: Our study showed that rHuEPO-induced hypertension might involve indirect (hematological) and direct (renal) effects which varies according to the dose used. Thus, rHuEPO therapy should be performed rationally and under adequate surveillance, as hypertension develops even with lower doses. Especial caution with higher doses should be taken, as rHuEPO-induced hypertension leads to early renal damage without alterations in traditional markers of renal function, thus masking the serious adverse effects and risks.
- Impaired renal endothelial nitric oxide synthase and reticulocyte production as modulators of hypertension induced by rHuEPO in the ratPublication . Ribeiro, Sandra; Garrido, Patrícia; Fernandes, João; Vala, Helena; Rocha-Pereira, Petronila; Costa, Elísio; Belo, Luís; Reis, Flávio; Santos-Silva, AliceOur aim was to study the effect of a broad range of recombinant human erythropoietin (rHuEPO) doses on hematological and biochemical parameters, blood pressure (BP), renal function and damage in the rat, focusing on endothelial nitric oxide synthase (eNOS) and hypoxia-inducible factors (HIFs). Male Wistar rats were divided in 5 groups receiving different doses of rHuEPO (100, 200, 400 and 600IU/kg body weight (BW)/week) and saline solution (control), during 3weeks. Blood and 24h urine were collected to perform hematological and biochemical analysis. BP was measured by the tail-cuff method. Kidney tissue was collected to mRNA and protein expression assays and to characterize renal lesions. A dose-dependent increase in red blood cells count, hematocrit and hemoglobin levels was found with rHuEPO therapy, in rHuEPO200, rHuEPO400 and rHuEPO600 groups. Increased reticulocyte count was found in rHuEPO400 and rHuEPO600 groups. BP raised in all groups receiving rHuEPO. The rHuEPO200 and rHuEPO600 groups presented increased kidney protein levels of HIF2α, a reduction in kidney protein levels of eNOS, and the highest grade of vascular and tubular renal lesions. Our study showed that rHuEPO-induced hypertension is present before significant hematological changes occur and, therefore, might involve direct (renal) and indirect (hematological) effects, which varies according to the dose used. The presence of renal hypoxia reduces eNOS activity. Excessive erythrocytosis increases blood hyperviscosity, which can be modulated by an increase in reticulocytes. Hypertension leads to early renal damage without alterations in traditional markers of renal function, thus underestimating the serious adverse effects and risks.
- Inflammatory and hematological disturbances associated with resistance to recombinant human erythropoietin therapy in CKD anemia in a rat modelPublication . Ribeiro, Sandra; Garrido, Patrícia; Fernandes, João; Vala, Helena; Rocha-Pereira, Petronila; Costa, Elísio; Belo, Luís; Reis, Flávio; Santos-Silva, Alice
- Iron-hepcidin dysmetabolism, anemia and renal hypoxia, inflammation and fibrosis in the remnant kidney rat modelPublication . Garrido, Patrícia; Ribeiro, Sandra; Fernandes, João; Vala, Helena; Bronze-da-Rocha, Elsa; Rocha-Pereira, Petronila; Belo, Luís; Costa, Elísio; Santos-Silva, Alice; Reis, FlávioAnemia is a common complication of chronic kidney disease (CKD) that develops early and its severity increases as renal function declines. It is mainly due to a reduced production of erythropoietin (EPO) by the kidneys; however, there are evidences that iron metabolism disturbances increase as CKD progresses. Our aim was to study the mechanisms underlying the development of anemia of CKD, as well as renal damage, in the remnant kidney rat model of CKD induced by 5/6 nephrectomy. This model of CKD presented a sustained degree of renal dysfunction, with mild and advanced glomerular and tubulointerstitial lesions. Anemia developed 3 weeks after nephrectomy and persisted throughout the protocol. The remnant kidney was still able to produce EPO and the liver showed an increased EPO gene expression. In spite of the increased EPO blood levels, anemia persisted and was linked to low serum iron and transferrin levels, while serum interleukin (IL)-6 and high sensitivity C-reactive protein (hs- CRP) levels showed the absence of systemic inflammation. The increased expression of duodenal ferroportin favours iron absorption; however, serum iron is reduced which might be due to iron leakage through advanced kidney lesions, as showed by tubular iron accumulation. Our data suggest that the persistence of anemia may result from disturbances in iron metabolism and by an altered activity/function of EPO as a result of kidney cell damage and a local inflammatory milieu, as showed by the increased gene expression of different inflammatory proteins in the remnant kidney. In addition, this anemia and the associated kidney hypoxia favour the development of fibrosis, angiogenesis and inflammation that may underlie a resistance to EPO stimuli and reduced iron availability. These findings might contribute to open new windows to identify putative therapeutic targets for this condition, as well as for recombinant human EPO (rHuEPO) resistance, which occurs in a considerable percentage of CKD patients.
- Pathological and molecular mechanisms underlying resistance to recombinant human erythropoietin therapy in the remnant kidney rat model of chronic kidney disease associated anemiaPublication . Ribeiro, Sandra; Garrido, Patrícia; Fernandes, João; Vala, Helena; Rocha-Pereira, Petronila; Costa, Elísio; Belo, Luís; Reis, Flávio; Santos-Silva, AliceAnemia of chronic kidney disease (CKD) can be corrected by treatment with recombinant human erythropoietin (rHuEPO); however, some patients become hyporesponsive. The molecular mechanisms underlying this resistance remain to be elucidated. Our aim was to study hyporesponsiveness to rHuEPO therapy using the remnant kidney rat model of anemia associated with CKD induced by 5/6 nephrectomy. At starting, male Wistar rats were divided in 3 groups, for a 3-week protocol: Sham, CRF (vehicle) and two rHuEPO (200 IU/kg body weight [BW]/week) treated groups; at the end of protocol, the rHuEPO treated rats were subdivided in responders (CRF200) and non-responders (CRF200NR), according to their hematologic response; blood, cellular and tissue studies were performed. The CRF200 group achieved correction of anemia, while the CRF200NR group developed anemia, after an initial response (1st week) to rHuEPO therapy. CRF and CRF200NR groups presented a trend to higher serum CRP levels; CRF200NR showed also high levels of renal inflammatory markers, such as interleukin (IL)-6, IL-1β, nuclear factor kappa B, connective tissue growth factor (CTGF) and transforming growth factor beta 1 (TGF-β1); no changes were found in iron metabolism. Our data suggest that the development of anemia/rHuEPO hyporesponsiveness is associated with a higher systemic and renal inflammatory condition, favoring hypoxia and triggering an increase in renal expression of HIF-1α, TGF-β1 and CTGF that will further aggravate renal fibrosis, which will enhance the inflammatory response, creating a cycle that promotes disease progression. New therapeutic strategies to reduce inflammation in CKD patients could improve the response to rHuEPO therapy and reduce hyporesponsiveness.