Browsing by Author "Aranda, E"

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    Cardiovascular risk factors in vegetarians: Normalization of hyperhomocysteinemia with vitamin B-12 and reduction of platelet aggregation with n-3 fatty acids
    (PERGAMON-ELSEVIER SCIENCE LTD, 2000) Mezzano, D; Kosiel, K; Martinez, C; Cuevas, A; Panes, O; Aranda, E; Strobel, P; Perez, DD; Pereira, J; Rozowski, J; Leighton, F
    Hyperhomocysteinemia in association with vitamin B-12 deficiency, and increased platelet aggregation, probably due to dietary lack of n-3 fatty acids, constitute cardiovascular risk factors frequently observed in vegetarians. We tested if administration of vitamin B-12 normalizes the concentration of total plasma homocysteine, and if intake of eicosapentaenoic (20:5n-3) and docosahexaenoic (22:6n-3) fatty acids modulates platelet function in a population of lactoovovegetarians. One week after a single intramuscular injection of cyanocobalamin (10000 mug) in 18 individuals, serum vitamin B-12 increased from 149+/-63 pg/mL to 532+/-204 pg/mL (p<0.0001) and total tHcy dropped from 12.4+/-4.7 to 7.9+/-3.1 mol/L (p<0.0001). Ten of fourteen of these vegetarians completed an 8-week supplementation with 700 mg/day of each eicosapentaenoic and docosahexaenoic acids. Increased incorporation of these fatty acids into plasma lipids was observed in all of them, together with a significant reduction in maximum percentage or slope of platelet aggregation with all the agonists tested (ADP, epinephrin, collagen, arachidonic acid). No significant change in bleeding time was observed after n-3 fatty acid trial. Supplementation with vitamin B-12 and n-3 fatty acids corrects hyperhomocysteinemia and reduces platelet reactivity to agonists in vegetarians. Whether this supplementation improves the already reduced cardiovascular morbidity and mortality associated with vegetarian diet has yet to be demonstrated. (C) 2000 Elsevier Science Ltd. All rights reserved.
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    Hemostatic disorder of uremia: The platelet defect, main determinant of the prolonged bleeding time, is correlated with indices of activation of coagulation and fibrinolysis
    (GEORG THIEME VERLAG KG, 1996) Mezzano, D; Tagle, R; Panes, O; Perez, M; Downey, P; Munoz, B; Aranda, E; Barja, P; Thambo, S; Gonzalez, F; Mezzano, S; Pereira, J
    Several parameters of primary hemostasis and markers of activation of coagulation and fibrinolysis were measured in 38 patients with severe (creatinine clearance <20 ml/min) chronic renal failure (CRF) without dialysis and diseases or drugs affecting hemostasis. Bleeding time (BT) was prolonged in 25/48 patients, and was correlated with age of patients, severity of renal failure, hematocrit, impairment in platelet aggregation-secretion and decrease in platelet ATP content. Defects in von Willebrand factor played no role in the prolongation of the BT. Multivariate analysis showed that only platelet dysfunction and severity of renal disease were independent predictors of the BT in uremia. The platelet functional disorder was significantly correlated with a reduction in platelet ATP and ADP.
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    Human intraplatelet 5-hydroxytryptamine is correlated with mean platelet survival time
    (PERGAMON-ELSEVIER SCIENCE LTD, 1996) Aranda, E; Pereira, J; Ajenjo, C; Prieto, C; Sepulveda, S; Mezzano, D
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    Inflammation, not hyperhomocysteinemia, is related to oxidative stress and hemostatic and endothelial dysfunction in uremia
    (BLACKWELL SCIENCE INC, 2001) Mezzano, D; Pais, EO; Aranda, E; Panes, O; Downey, P; Ortiz, M; Tagle, R; Gonzalez, F; Quiroga, T; Caceres, MS; Leighton, F; Pereira, J
    Background. Several cardiovascular risk factors are present in patients with chronic renal failure (CRF), among which are systemic inflammation and hyperhomocysteinemia. Increased oxidative stress, endothelial activation/dysfunction, and coagulation activation are considered integral components of the inflammatory response, but have also been proposed as mediators of plasma homocysteine (tHcy)-induced cell damage. Using correlation analysis, we assessed the relative contributions of inflammation and hyperhomocysteinemia in the abnormal oxidative stress, endothelial activation/dysfunction, and hemostasis activation in patients with CRF.
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    Platelet aging in vivo is associated with activation of apoptotic pathways: Studies in a model of suppressed thrombopoiesis in dogs
    (SCHATTAUER GMBH-VERLAG MEDIZIN NATURWISSENSCHAFTEN, 2002) Pereira, J; Soto, M; Palomo, I; Ocqueteau, M; Coetzee, LM; Astudillo, S; Aranda, E; Mezzano, D
    The mechanism(s) involved in the clearance of senescent platelets are largely unknown. We have recently demonstrated that platelet aging in vivo is associated with loss of membrane phospholipid asymmetry, a universal phenomenon in cells undergoing apoptosis. Thus, We postulated that senescent platelets may exhibit programmed cell death changes, which may trigger their removal from circulation. Since platelets contain the apoptosis machinery as well as mitochondria, a key organelle in the regulation of apoptosis, we studied the appearance of apoptotic-like changes during platelet aging in vivo. To investigate this, we assessed changes in mitochondrial membrane potential in circulating canine platelets during decline in platelet Count after suppression of thrombopoiesis by estradiol injection. a validated model to obtain circulating platelets of increasing mean ace. Phosphatidyl-serine (PS) exposure was determined by flow cytometry by binding of FITC-labeled annexin V. Mitochondrial Deltapsi was studied with the cationic lipophilic dye DIOC6 (3) and the J-aggregate-forming cation JC-1 and analysis by flow cytometry. The proportion of platelets with exposed PS rose significantly with age, from 2.88% before to 6.7%. 8 days after estradiol injection. By flow, cytometry it was demonstrated a significant decreased in DIOC6 (3) fluorescence (median fluorescence intensity 791 98 vs 567 1021 day 0 vs day 8 post injection of estradiol, respectively n:11; p<0.01), consistent with mitochondrial &UDelta;ψ collapse. JC-1 has the unique property of forming J-aggregates tinder high mitochondrial &UDelta;ψ (red fluorescence, FL2) whereas the monomeric form fluoresces in green (FL1). Aged platelets in vivo, loaded with JC-1, exhibited a significant increase in FL1/FL2 ratio (2.5&PLUSMN;1.7 vs 4.7&PLUSMN;1.6, day 0 vs day 8 post injection of estradiol, respectively n:13; p<0.05). confirming the mitochondrial Deltapsi alteration.
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    Platelet aging in vivo is associated with loss of membrane phospholipid asymmetry
    (F K SCHATTAUER VERLAG GMBH, 1999) Pereira, J; Palomo, I; Ocqueteau, M; Soto, M; Aranda, E; Mezzano, D
    The mechanism(s) involved in the clearance of senescent platelets are largely unknown. The loss of membrane phospholipid (PL) asymmetry, with phosphatidylserine (PS) exposure appears to be an important signal for the ingestion by macrophages of apoptotic nucleated cells and it has also been suggested as a signal for the removal of aged erythrocytes. Accordingly, it seems possible that the clearance of normal aged platelets from circulation might be triggered by PS exposure. To investigate this, we determined PS exposure in human aging platelets taking advantage of the relationship between platelet density and platelet age and in dog platelets in a model of platelet aging in vivo. PS exposure was determined in two experimental conditions: 1) human platelet density subpopulations obtained by centrifugation in arabinogalactan gradients; 2) circulating canine platelets during decline in platelet count after suppression of thrombopoiesis following estradiol injection. PS exposure was determined by flow cytometry after labeling the cells with FITC-conjugated annexin V. The proportion of human platelets with exposed PS was significantly higher in high density (HD) platelets compared to low density (LD) platelets (11.3 +/- 8.0% vs 5.2 +/- 3.7%; p < 0.05, respectively). In dogs, the proportion of cells with exposed PS rises dramatically with age, from 3.1 +/- 0.4% before to 17.7 +/- 12.3% ten days after estradiol injection. These findings suggest that platelet aging is associated with loss of phospholipid asymmetry and PS exposure on the outer leaflet of cell membrane, which may play an important role in the recognition and subsequent removal of senescent platelets.
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    Template bleeding time and PFA-100® have low sensitivity to screen patients with hereditary mucocutaneous hemorrhages
    (2004) Quiroga, T; Goycoolea, M; Muñoz, B; Morales, M; Aranda, E; Panes, O; Pereira, J; Mezzano, D
    Objectives and patients: We compared the template bleeding time (BT) and closure time (CT) in the PFA-100(R) as screening tests in 148 consecutive patients With unequivocal mucocutaneous bleeding and positive family history. Exclusion criteria: drug intake, concomitant diseases including minor infections, low platelet Count, diseases of secondary hemostasis. Results: Type I von Willebrand disease (VWD-1) was diagnosed in 26 patients, primary platelet secretion defect (PSD) in 33, VWD-1 + PSD in nine, whereas 80 patients did not comply with the criteria for known hemostatic disorders (UD, unknown diagnosis). BT and CT were prolonged in 35.8% and 29.7% of all the patients, respectively (P = 0.23). Sensitivity increased to 48% if an abnormality of BT and/or CT was considered. Same comparisons for BT and CT in each diagnostic category were. respectively: 42 vs. 61.5% in VWD-1 (P = 0.18), 42 vs. 24% in platelet secretion defects (P = 0.11), 67 vs. 89% in VWD-1 + PSD (P = 0.50), and 27.5 vs. 15% in UD (P = 0.06). Conclusion: Both tests were relatively insensitive and not significantly different in detecting incoming patients with mucocutancous hemorrhages. In patients with VWD-1 the PFA-100(R) performed slightly better, whereas the opposite occurred in those patients with platelet secretion defects. In the UD group, both tests lost sensitivity, but the BT detected 1.8 times more patients than the PFA-100(R). Given the large proportion of undiagnosed bleeders and the overall low sensitivity of these tests, clinical decisions still rely on the medical history and etiological diagnosis of the bleeding disorder.
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    Thrombin generation in platelet-poor plasma is normal in patients with hereditary mucoputaneous haemorrhages
    (2003) Quiroga, T; Goycoolea, M; Giesen, PLA; Morales, M; Muñoz, B; Aranda, E; Rodríguez, S; Panes, O; Martínez, C; Pereira, J; Mezzano, D
    Mild hereditary bleeding disorders presenting with mucocutaneous haemorrhages are usually difficult to diagnose. We measured thrombin generation in platelet-poor plasma (TG-PPP) in 206 patients with a clinically unequivocal bleeding tendency: 45 with von Willebrand disease (vWD), 49 with platelet aggregation/secretion defects (PASD), 10 with a combination of both and 102 who did not fit the diagnostic criteria for any known haemostatic disorder. TG-PPP was not significantly different from controls in all patient groups, indicating that an abnormality in the plasmatic clotting system is unlikely to contribute to the bleeding in patients with type 1 vWD and PASD. In patients with undiagnosed mild hereditary bleeding disorders, there must be other mechanisms which explain the abnormal haemorrhagic tendency, most likely as yet unrecognized defects in platelet-vessel wall interaction. As a next step we plan to investigate thrombin generation in PRP. Copyright (C) 2003 S. Karger AG, Basel.
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    Vegetarians and cardiovascular risk factors
    (1999) Mezzano, D; Muñoz, X; Martínez, C; Cuevas, A; Panes, O; Aranda, E; Guasch, V; Strobel, P; Muñoz, B; Rodríguez, S; Pereira, J; Leighton, F
    We studied hemostatic and inflammatory cardiovascular risk factors (CVRF), and total plasma homocysteine (tHcy) in 26 vegetarians (23 lacto- or ovolactovegetarians and 3 vegans), matched by age, sex and socioeconomic status with omnivorous controls. Vegetarians had significantly lower proportion of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids in plasma lipids, significantly shortened bleeding time, and increased blood platelet count and in vitro platelet function (aggregation and secretion). Plasma levels of all coagulation or fibrinolytic factors and natural inhibitors synthesized in the liver were lowa in vegetarians than in controls. Whereas for some factors this decrease was statistically significant (fibrinogen, factor VIIc, antithrombin III, protein S, plasminogen) for the remaining (factors VIIIc, Vc, prothrombin, protein C) a trend in the same direction was found. For hemostatic proteins of predominantly extrahepatic origin (von Willebrand factor, tPA, PAI-1) this tendency was not present. No significant differences in inflammatory proteins (C-reactive protein and al-protease inhibitor) were detected in both groups. tHcy was significantly increased in vegetarians, and correlated only with cobalamin levels. The increased platelet function and tHcy found in vegetarians may counteract the known cardiovascular health benefits of vegetarian diet (VD).