Browsing by Author "Panes, Olga"
Now showing 1 - 9 of 9
Results Per Page
Sort Options
- ItemClot lysis time in platelet-rich plasma: Method assessment, comparison with assays in platelet-free and platelet-poor plasmas, and response to tranexamic acid(TAYLOR & FRANCIS INC, 2012) Panes, Olga; Padilla, Oslando; Matus, Valeria; Saez, Claudia G.; Berkovits, Alejandro; Pereira, Jaime; Mezzano, DiegoFibrinolysis dysfunctions cause bleeding or predisposition to thrombosis. Platelets contain several factors of the fibrinolytic system, which could up or down regulate this process. However, the temporal relationship and relative contributions of plasma and platelet components in clot lysis are mostly unknown. We developed a clot lysis time (CLT) assay in platelet-rich plasma (PRP-CLT, with and without stimulation) and compared it to a similar one in platelet-free plasma (PFP) and to another previously reported test in platelet-poor plasma (PPP). We also studied the differential effects of a single dose of tranexamic acid (TXA) on these tests in healthy subjects. PFP- and PPP-CLT were significantly shorter than PRP-CLT, and the three assays were highly correlated (p < 0.0001). PFP- and PPP-, but more significantly PRP-CLT, were positively correlated with age and plasma PAI-1, von Willebrand factor, fibrinogen, LDL-cholesterol, and triglycerides (p < 0.001). All these CLT assays had no significant correlations with platelet aggregation/secretion, platelet counts, and pro-coagulant tests to explore factor X activation by platelets, PRP clotting time, and thrombin generation in PRP. Among all the studied variables, PFP-CLT was independently associated with plasma PAI-1, LDL-cholesterol, and triglycerides and, additionally, stimulated PRP-CLT was also independently associated with plasma fibrinogen. A single 1 g dose of TXA strikingly prolonged all three CLTs, but in contrast to the results without the drug, the lysis times were substantially shorter in non-stimulated or stimulated PRP than in PFP and PPP. This standardized PRP-CLT may become a useful tool to study the role of platelets in clot resistance and lysis. Our results suggest that initially, the platelets enmeshed in the clot slow down the fibrinolysis process. However, the increased clot resistance to lysis induced by TXA is overcome earlier in platelet-rich clots than in PFP or PPP clots. This is likely explained by the display of platelet pro-fibrinolytic effects. Focused research is needed to disclose the mechanisms for the relationship between CLT and plasma cholesterol and its potential pathophysiologic and clinical relevance.
- ItemHigh prevalence of bleeders of unknown cause among patients with inherited mucocutaneous bleeding. A prospective study of 280 patients and 299 controls(FERRATA STORTI FOUNDATION, 2007) Quiroga, Teresa; Goycoolea, Manuela; Panes, Olga; Aranda, Eduardo; Martinez, Carlos; Belmont, Sabine; Munoz, Blanca; Zuniga, Pamela; Pereira, Jaime; Mezzano, DiegoBackground and Objectives
- ItemHuman platelets synthesize and express functional tissue factor(AMER SOC HEMATOLOGY, 2007) Panes, Olga; Matus, Valeria; Saez, Claudia G.; Quiroga, Teresa; Pereira, Jaime; Mezzano, DiegoThe source and significance of bloodborne tissue factor (TF) are controversial. TF mRNA, protein, and TF-dependent procoagulant activity (PCA) have been detected in human platelets, but direct evidence of TF synthesis is missing. Nonstimulated monocyte-free platelets from most patients expressed TF mRNA, which was enhanced or induced in all of them after platelet activation. Immunoprecipitation assays revealed TF protein (mainly of a molecular weight [Mr] of approximately 47 kDa, with other bands of approximately 35 and approximately 60 kDa) in nonstimulated platelet membranes, which also increased after activation. This enhancement was concomitant with TF translocation to the plasma membrane, as demonstrated by immunofluorescence-confocal microscopy and biotinylation of membrane proteins. Platelet PCA, assessed by factor Xa (FXa) generation, was induced after activation and was inhibited by 48% and 76% with anti-TF and anti-FVIIa, respectively, but not by intrinsic pathway inhibitors. Platelets incorporated [35S]-methionine into TF proteins with Mr of approximately 47 kDa, approximately 35 kDa, and approximately 60 kDa, more intensely after activation. Puromycin but not actinomycin D or DRB (5,6-dichloro-1 -beta-D-ribofuranosylbenzimidazole)inhibited TIF neosynthesis. Thus, human platelets not only assemble the clotting reactions on their membrane, but also supply their own TIF for thrombin generation in a timely and spatially circumscribed process. These observations simplify, unify, and provide a more coherent formulation of the current cellbased model of hemostasis.
- ItemIncreased number of circulating endothelial cells and plasma markers of endothelial damage in chronic cocaine users(PERGAMON-ELSEVIER SCIENCE LTD, 2011) Saez, Claudia G.; Olivares, Paulina; Pallavicini, Julio; Panes, Olga; Moreno, Natalia; Massardo, Teresa; Mezzano, Diego; Pereira, JaimeBackground: Cocaine use has been related with the development of accelerated atherosclerosis and with an increased risk of cardiac and cerebrovascular events, such as myocardial infarction, sudden cardiac death, and ischemic stroke. The underlying mechanisms leading to these complications are not fully understood, although thrombus formation and altered vascular function are prominent findings.
- ItemMonitoring of anticoagulant treatment with Unfractionated Heparin in pediatrics(2022) Aguirre, Noemi; Rivera, Carolina; Munoz, Gonzalo; Valle, Patricio; Panes, Olga; Zuniga, PamelaUnfractionated heparin (UFH) is the most widely used anticoagulant in hospitalized patients. The therapeutic range (TR) was defined in adults according to the prolongation of the activated Partial Thromboplastin Time (aPTT). However, the recommendation is to maintain a therapeutic range with anti-factor Xa assay (antiFXa). As this technique is more complex to perform and less available, it is recommended to make local correlation curves of aPTT with antiFXa. Objective: to determine the correlation between the values of aPTT and antiFXa in patients treated with UFH. Patients and Method: 52 patients between 2 days to 14 years of age hospitalized in the Pediatric Critical Patient Unit were recruited. They received treatment with UFH in continuous infusion for at least 24 hours. aPTT and antiFXa tests were performed according to the moment of anticoagulation. To evaluate the concordance of the levels of aPTT with those of antiFXa, the Kappa statistical coefficient of Landis and Koch was used. Results: 105 samples were collected from 52 patients. The overall concordance was 0.452 (moderate correlation). In patients aged < 1 month (n = 40), a considerable correlation was evident (r = 0.617); in those from 1 month to < 6 months (n = 18) and 6 months -< 12 months with aPTT < 120 seconds (n = 11), also showed a considerable correlation (r = 0.636 and 0.615, respec-tively), while in those aged > 12 months (n = 37) with aPTT < 120 seconds, a moderate correlation was evident (r = 0.454). Conclusion: In our population, there is a moderate correlation between the values of aPTT and antiFXa.
- ItemNovel loci involved in platelet function and platelet count identified by a genome-wide study performed in children(FERRATA STORTI FOUNDATION, 2011) Guerrero, Jose A.; Rivera, Jose; Quiroga, Teresa; Martinez Perez, Angel; Isabel Anton, Ana; Martinez, Constantino; Panes, Olga; Vicente, Vicente; Mezzano, Diego; Soria, Jose Manuel; Corral, JavierBackground
- ItemPlatelet activation in chronic cocaine users: Effect of short term abstinence(TAYLOR & FRANCIS INC, 2011) Pereira, Jaime; Saez, Claudia G.; Pallavicini, Julio; Panes, Olga; Pereira Flores, Karla; Cabreras, Manuel J.; Massardo, Teresa; Mezzano, DiegoCocaine abuse increases the risk of cardiac and cerebrovascular events, such as myocardial infarction and ischemic stroke. The underlying mechanisms leading to these complications are not fully understood although intravascular thrombus formation has been observed. The aim of this study was to investigate the existence of platelet activation and the effect of short-term abstinence in chronic cocaine consumers. We studied 23 cocaine dependent individuals (aged 20-54 years) who met DSM-IV criteria for cocaine dependence and 20 controls. Samples were obtained at baseline, within 72 h of last drug exposure and after 4 weeks of controlled abstinence. Monocyte-platelet aggregates (MPA) were measured by flow cytometry. Plasma levels of soluble CD40L (sCD40L), Neutrophil-Activating Peptide-2 (NAP-2) and regulated on activation normal T cells expressed and secreted (RANTES) were determined by ELISA. Levels of MPA, sCD40L, NAP-2 and RANTES were significantly higher (all p < 0.05) in cocaine addicts compared to controls at baseline. All the parameters returned to values similar to the control group after 4-weeks' abstinence. Levels of sCD40L and RANTES were associated with an index of intensity of drug consumption (p < 0.02). Our results demonstrate that cocaine use induces platelet activation which is a prominent finding after recent consumption. The persistence over time of this condition may contribute not only to acute thrombotic complications but also to the development of early-onset atherosclerotic process observed in cocaine abusers.
- ItemProcarboxypeptidase U (TAFI) and the Thr325Ile proCPU polymorphism in patients with hereditary mucocutaneous hemorrhages(ELSEVIER, 2009) Matus, Valeria; Willemse, Johan; Quiroga, Teresa; Goycoolea, Manuela; Aranda, Eduardo; Panes, Olga; Pereira, Jaime; Hendriks, Dirk; Mezzano, DiegoBackground: Patients with hereditary mucocutaneous bleeding are difficult to diagnose and many of them fulfill the category of bleeders of unknown cause (BUC). The pathogenic role of hyperfibrinolysis has received little attention, despite the successful use of antifibrinolytic drugs in treating many of these patients. Theoretically, decreased plasma procarboxypeptidase U (proCPU) levels or lower carboxypeptidase U (CPU) stability would result in higher fibrinolytic activity and bleeding tendency.
- ItemSerotonin secretion by blood platelets: accuracy of high-performance liquid chromatography-electrochemical technique compared with the isotopic test and use in a clinical laboratory(2023) Aranda, Eduardo; Iha, Seiki; Solari, Sandra; Rodriguez, David; Romero, Viviana; Villarroel, Luis; Pereira, Jaime; Panes, Olga; Mezzano, DiegoBackground: Mild secretion defects are the most frequent and challenging blood platelet disorders to diagnose. Most d-granule secretion tests lack validation, are not quantitative, or have unreliable response to weak platelet agonists.