Browsing by Author "Teixeira, Frederico"
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- Altered erythrocyte membrane band 3 profile in chronic renal failure patients under haemodialysisPublication . Costa, Elísio; Rocha, Susana; Rocha-Pereira, Petronila; Castro, Elisabeth; Reis, Flávio; Teixeira, Frederico; Miranda, Vasco; Sameiro-Faria, Maria; Loureiro, Alfredo; Quintanilha, Alexandre; Belo, Luís; Santos-Silva, AliceOur aim was to study changes in RBC membrane band 3 profile, as a cumulative marker of RBC changes, in chronic renal failure (CRF) patients under haemodialysis and recombinant human erythropoietin (rhEPO) therapy and its linkage with resistance to this therapy. We studied 63 CRF patients, 32 responders and 31 non -responders to rhEPO therapy, and 26 healthy individuals matched for age and gender. We evaluated the band 3 profile and membrane -bound haemoglobin (MBH). Total serum bilirrubin, glutathione peroxidase (GPx) and superoxide dismutase activities, RBC count, haematocrit, haemoglobin concentration, haematimetric indices and reticulocyte were also evaluated. CRF patients presented anaemia, slightly regenerative, as showed by the decreased RBC count, Hb and haematocrit, alongside with an increased reticulocyte count, RPI and RDW values. CRF patients showed a statistically significant decrease in high molecular weight aggregates and proteolytic fragments (Pfrag), and a rise in Band 3 monomer. A rise in GPx and a trend to lower values of MBH were also found in CRF patients. A positive correlation was found between Pfrag and, Hb and haematocrit. When comparing the haematological data between the two groups of CRF patients, we found that non -responders patients were more anaemic, and presented a statistically significant decrease in Pfrag, and a trend for a rise in MBH, suggesting a higher RBC damage. Our data suggest that band 3 profile seems to be a good marker of erythrocyte changes in CRF patients. These changes seem to be associated with a younger RBC population, but also with a rise in RBC damage, which is enhanced in non -responders CRF patients. Band 3 profile could be used as a marker of RBC changes in these patients and in the understanding of the mechanism of resistance to rhEPO therapy.
- Fibrinolytic activity and vascular access inchronic renal failure patients under haemodialysisPublication . Costa, Elísio; Rocha, Susana; Rocha-Pereira, Petronila; Castro, Elisabeth; Reis, Flávio; Teixeira, Frederico; Miranda, Vasco; Sameiro-Faria, Maria; Loureiro, Alfredo; Quintanilha, Alexandre; Belo, Luís; Santos-Silva, AliceOur aim was to study the relationship between fibrinolytic activity and the type of vascular access in haemodialysis patients. We measured the circulating antigen levels of plasminogen activator inhibitor type-1 (PAI-1), tissue plasminogen activator (tPA) and D-dimers. This study was performed in 50 CRF patients under regular haemodialysis, 11 with central venous dialysis catheter and 39 with AV-fistula, and in 25 healthy controls. Compared with controls, CRF patients presented significantly lower levels of tPA and with higher levels of D-dimers. In CRF patients, the levels of D-dimers correlated positively and significantly (r=0.359, p=0.01) with rhEPO doses (rhEPO/Kg/week) and negatively with haemoglobin levels (r=-0.335, p=0.017). When comparing the two groups of CRF patients, we found that those with central venous catheter vascular access presented a statistical significant rise in D-dimer and tPA plasma levels. No difference was found between the two groups of patients concerning the plasma levels PAI-1. Our results showed an altered haemostasis in CRF patients, as suggested by the rise in D-dimer, an index of fibrin turnover and intravascular thrombogenesis. The increased levels of D-dimer and tPA in CRF patients, particularly in those using central venous dialysis catheters, led us to propose a relationship between the type of vascular access chosen for the haemodialysis procedure, and the risk of thrombogenesis. It seems reasonable to assume that these patients present an increased risk for cardiovascular disease events.
- Haemorheological changes during recombinante human erythropoietin therapy in a rat model of renal failure induced by partial nephrectomyPublication . Costa, Elísio; Reis, Flávio; Rocha-Pereira, Petronila; Baptista, Sofia; Dias, André; Rocha, Susana; Castro, Elisabeth; Miranda, Vasco; Faria, Maria Sameiro; Loureiro, Alfredo; Lemos, Edite Teixeira de; Parada, Belmiro; Figueiredo, Arnaldo; Quintanilha, Alexandre; Teixeira, Frederico; Belo, Luís; Santos-Silva, AliceThe aim of this work was to study the effect of recombinant human erythropoietin (rhEPO) the rapy on haemorheological parameters, by using a rat model of chronic renal failure (CRF) induced by partial (3/4) nephrectomy. The study used adult male Wistar rats and was performed in three groups: a control one (n=6) and in two groups with induced chronic renal failure (n=9), being one of them submitted to rhEPO the rapy (n=4). Blood samples from the control group were collected at the beginning and at the end of the experimental procedure and from CRF rats at 3, 5, 8, 12 and 15 weeks after surgical partial nephrectomy. Haemorheology and renal function were evaluated. Three weeks after the 3/4 nephrectomy, a statistically significant increase in serum urea and creatinine concentrations were found. This increase in renal function markers remained high along the 12 weeks of experimental procedure. Comparing with controls, rhEPO treated rat have showed a statistically significant progressive increase in haemoglobin (Hb), haematocrit (Ht), red blood cells (RBC) count, mean cell volume (MCV), mean cell Hb (MCH) and red cell distribution width (RDW), showing at 12 weeks an inverse change, though still presenting significant higher values; a decrease in platelet counts, during the first 9 weeks of rhEPO therapy. When comparing haemorheological data from non-treated CRF and controls, we found only a trend to increased MCV and MCH values and a decrease in reticulocyte count. Comparing the two groups of CRF rats, we found that rhEPO treated rats presented significantly higher values in RBC, Hb, Ht and RDW. In both groups of CRF rats, at five weeks, there was a decrease in their values, showing at the end a significantly lower value when compared to controls. No consistent alterations were found in white blood cells in CRF rats, with or without rhEPO therapy. Partial nephrectomy seems to be a suitable methodology to induce CRF in rats and to study erythropoiesis biology. The rhEPO therapy is associated with an increased erythropoietic stimulation and a decrease in platelet count.
- Higher fibrinolytic and inflammatory markers are associated with central venous catheters use in chronic kidney disease patients under haemodialysisPublication . Costa, Elísio; Rocha, Susana; Rocha-Pereira, Petronila; Castro, Elisabeth; Reis, Flávio; Teixeira, Frederico; Miranda, Vasco; Faria, Maria Sameiro; Loureiro, Alfredo; Quintanilha, Alexandre; Belo, Luís; Santos-Silva, Alice