A. Silva

In vitro and in vivo evaluation of blood coagulation activation of polyvinyl alcohol hydrogel plus dextran-based vascular grafts.

Polyvinyl alcohol hydrogel (PVA) is a water-soluble synthetic polymer that is commonly used in biomedical applications including vascular grafting. It was argued that the copolymerization of PVA with dextran (Dx) can result in improvement of blood-biomaterial interactions. The focus of this experimental study was to assess that interaction through an in vivo and in vitro evaluation of the coagulation system activation. The thrombogenicity of the copolymer was determined by quantification of platelet adhesion through the lactate dehydrogenase assay, determination of whole blood clotting time, and by quantification of platelet activation by flow cytometry. The thrombin-antithrombin complex blood levels were also determined. The obtained results for the in vitro assays suggested a non-thrombogenic profile for PVA/Dx. Additionally in vivo coagulation and hematological parameters were determined in an animal model after PVA/Dx vascular graft implantation. For coagulation homeostasis assessment, the intrinsic and extrinsic pathways activation was determined by measuring prothrombin time (PT) and activated partial thromboplastin time (aPTT). Other markers of coagulation and inflammation activation including d-dimers, interleukin-6, and C-reactive protein were also assessed. The PVA/Dx copolymer tended to inhibit platelet adhesion/activation process and the contact activation process for coagulation. These results were also confirmed with the in vivo experiments where the measurements for APTT, interleukin-6, and C-reactive protein parameters were normal considering the species normal range of values. The response to those events is an indicator of the in vitro and in vivo hemocompatibility of PVA/Dx and it allows us to select this biomaterial for further preclinical trials in vascular reconstruction.

rhEPO for the Treatment of Erythropoietin Resistant Anemia in Hemodialysis Patients – Risks and Benefits

Anemia is a common complication in hemodialysis (HD) patients, mainly due to the insuffi‐ cient production of erythropoietin (EPO) by the failing kidneys [1]. Anemia itself can worsens cardiac function, cognitive function, exercise capacity and quality of life, and it has been independently associated with increased mortality and progression of renal disease [2, 3]. A successful management of anemia is, therefore, crucial, as it may improve clinical outcome. The introduction of recombinant human EPO (rhEPO) therapy to treat anemia of chronic kidney disease (CKD) patients reduced anemia, improving patients’ quality of life [3]. There is, however, a marked variability in the response to this therapy and 5-10% of patients develop resistance to rhEPO therapy [4]. Resistance to rhEPO therapy has been associated to inflam‐ mation, oxidative stress and “functional” iron deficiency, as major causes.

Renal Apoptosis Signalling in a Pig Haemorrhagic Model after Volume Replacement with HES 130/0.4 or Ringer's Solution

RENAL APOPTOSIS SIGNALLING IN A PIG HAEMORRHAGIC MODEL AFTER VOLUME REPLACEMENT WITH HES 130/0.4 OR RINGER’S SOLUTION R. Cruz*,y,z, H. Vala*,y, A. Machado*,y, C. Venâncio z, J.R. Mesquita*,y, A. Silva x, A.L. Ortiz{ and D. Ferreira *ESAV, IPV, yCI&DETS, IPV, zUTAD, xREQUIMTE, Portugal, {Le on University, Spain and CICV/FMV-ULHT, Portugal Introduction: TUNEL labelling is one of the most frequently used methods to detect apoptosis in renal tissues. The aim of this study was to evaluate kidney damage after acute haemorrhage and volume replacement with a colloid or a crystalloid, in a pig model. Materials and Methods: In accord with animal welfare regulations, three groups (n 5 6) of large white pigs were enrolled in the study. All groups underwent total intravenous anaesthesia and were subjected to acute haemorrhage and volume replacement with Ringer’s lactate or HES 130/0.4, 20 min after haemorrhage. Control pigs did not undergo bleeding and volume replacement. Pigs were killed and renal samples were taken and analyzed by the TUNEL method. ANOVA was used to compare data between groups. Results: An intense positive signal in tubular epithelial cells was observed in all samples. The level of signalling per mm was significantly lower in the group receiving Ringer’s lactate (11.94) compared with the group receiving HES130/0.4 (67.94) and controls (146.34) (P !0.05). Conclusions: Signalling levels were lower in pigs subjected to fluid replacement with Ringer’s lactate when compared with the control group. Ringer’s lactate might promote better renal perfusion in the presence of severe hypoperfusion. HISTOLOGICAL EVALUATION OF THE SPLEEN AFTER ACUTE BLEEDING FOLLOWED BY VOLUME REPLACEMENT WITH TWO DIFFERENT PHYSIOLOGICAL SOLUTIONS M. Cabral*, A. Ortiz y, C. Venâncio z, J. Mesquita x, C. N obrega x, A. Silva{, H. Vala x and D. Ferreira *Agrarian Superior School, IPV Viseu, Portugal, yUniversity of Le on, Spain, zIBMC-Porto, xCEETS-IPV Viseu, {REQUIMTE, Porto and CICVULHT, Lisboa, Portugal Introduction: The spleen is important for many haemopoietic and immunological functions, particularly in haemodynamic compensation during haemorrhagic shock, with a crucial role in restoring blood volume in situations of acute haemorrhage. The administration of physiological solutions is of great importance for the correction of circulating volume, avoiding complications due to hypovolaemia. The aim of this study was to evaluate histopathological changes in the spleen associated with volume replacement using two different physiological solutions (hydroxyethyl starch [HES] 130/0.4 and Ringer’s lactate), after acute controlled bleeding, in a pig model. Materials andMethods: Thirty-one large white pigs underwent total intravenous anaesthesia with propofol and remifentanil. A total of 25ml/kg of blood was removed passively over 20 min. Intravascular volume was replaced using Ringer’s lactate at 25 ml/kg (group 1, n 5 13) or HES130/0.4 at 20 ml/kg (group 2, n 5 11). Spleen samples were processed for routine histopathological evaluation. Results: Significant differences were found in lymphoid follicular hyperplasia between the control group and group 1, and between group 1 and group 2, with increased follicular hyperplasia in group 1. Conclusions: Volume replacement with HES130/0.4 may reduce follicular lymphoid hyperplasia when compared with volume replacement with Ringer’s lactate after acute bleeding.

Volume replacement with hydroxyethyl starch (HES) 130/0.4 and ringer lactate solution in pigs after severe haemorrhage: A small bowel mucosa preliminary study

Portuguese Foundation for Science and Technology under the project COMPETE: FCOMP-01-0124-FEDER-009525 (PTDC/CVT/101999/2008)