RESUMEN
The von Willebrand factor (VWF) is analysed as a bleeding and thrombotic risk marker. When the VWF level is increased, it predicts a thrombotic phenotype and when VWF level is low in plasma, the phenotype varies to bleeding disorder. But it is quite challenging to define when the level is low, normal or high taking into account that these values are capricious and overlap. This matter should be solved by extensive epidemiologic studies. VWD is a hereditary disorder with several described mutations. VWF is a major acute-phase reactant, besides the physiological conditions such as blood group and pregnancy that affect plasmatic VWF levels. Subjects with O blood group have 25% less VWF than those of non O blood groups, and the latter show higher thrombus burden. VWF would be sensitive though not specific diagnostic marker of myocardial infarction. For the assessment of bleeding severity there are special surveys, scores and pictorial charts. The identification of VWF as a thrombotic risk marker has not been clearly established yet, but it has been involved in stroke and coronary disease. We only have the specific replacement therapy for the bleeding phenotype and we can speculate that enoxaparin and PEG-hirudin are able to blunt the VWF rise in patients with unstable angina pectoris and it is associated with a more favourable clinical outcome. Only two questions remain: does VWF as a bleeding risk marker have the same value as a thrombotic risk marker? Will successful treatments like those achieved for bleeding be also possible in the future for thrombosis?
Asunto(s)
Hemorragia/diagnóstico , Trombosis/diagnóstico , Factor de von Willebrand , Hemorragia/etiología , Humanos , Factores de Riesgo , Trombosis/etiologíaRESUMEN
Most mutations identified in 2A VWD patients are localized in the A2 domain, although missense substitutions have also been recognized in the A1 domain. We describe a novel heterozygous missense mutation in the A1 domain of VWF gene responsible for type 2A phenotype. Analysis of the complete exon 28 was carried out in a patient and his mother with life-long histories of moderate to severe bleeding and laboratory data of type 2A VWD. The analysis of exon 28 of VWF gene showed a 3815 G â T transversion resulting in C1272F mutation. It is probably associated with a group I mechanism according to patients' clinical symptoms, and, in the case of the propositus, the lack of clinical response to treatment with desmopressin. The mutation was not found in 100 normal alleles. This substitution affected the normal S-S bound between C1272 and C1458, which is involved in A1 loop structure, altering the normal multimerization and function of VWF. The VWFpp/VWF:Ag ratio in the propositus and his mother was >3, suggesting a shortened survival of VWF. We believe it is important to report the complete clinical phenotype corresponding to the new mutation to increase the knowledge in the clinical field.
Asunto(s)
Mutación Missense , Enfermedad de von Willebrand Tipo 2/genética , Factor de von Willebrand/genética , Adolescente , Adulto , Desamino Arginina Vasopresina/uso terapéutico , Exones/genética , Femenino , Hemostáticos/uso terapéutico , Humanos , Masculino , Fenotipo , Enfermedad de von Willebrand Tipo 2/tratamiento farmacológicoRESUMEN
OBJECTIVE: Anticoagulation clinics have improved the time spent within therapeutic range and decreased hemorrhagic complications and costs in chronic oral anticoagulation. Whether these benefits correlate to patients' quality of life (QOL) remains to be determined. The impact of patients' perceptions about anticoagulation on QOL has not been evaluated. The objective of this study was to evaluate prospectively patients' perceptions and quality of life in patients chronically anticoagulated. RESEARCH DESIGN AND METHODS: A cross-sectional study was designed to investigate the prevalence of positive and negative perceptions about oral anticoagulation therapy (OAT) and to identify vulnerable groups. Patients anonymously completed the SF-36 survey and a questionnaire that focused on patients' perceptions of protection from thrombotic complications or fear of haemorrhage due to the anticoagulation. We related those perceptions to the General Health SF-36 score, to the patient's characteristics, the absolute bleeding risk (i.e. intended International Normalized Ratio [INR]), duration of therapy and medical attention. RESULTS: One thousand patients were included and 905 questionnaires evaluated. Most patients felt protected and better since the beginning of therapy (71.5% and 61.5%, respectively). Patient characteristics associated with negative perceptions were; female sex (Odds Ratio [OR] 1.58, 95% Confidence Interval [CI] 1.06-2.36, p = 0.01); patients with less than 1 year of therapy (OR 2.16, 95% CI 1.34-3.48, p = 0.006); those not satisfied with medical attention (OR 2.86, 95% CI 1.53-5.18, p = 0.0001); and those that modified their lifestyle (OR 2.75, 95% CI 1.49-4.91, p = 0.0002). Patients with a lower bleeding risk (INR 2.0-3.0) had more negative perceptions than those with a higher risk. Patients with negative perceptions achieved the lowest score in the SF-36 survey. Haemorrhages did not affect patients' perception or QOL. CONCLUSIONS: Patients' perceptions correlated with QOL. We were able to identify patient characteristics associated with poor QOL and thus the group of patients whose negative perceptions most warranted special attention from their clinicians.
Asunto(s)
Anticoagulantes/uso terapéutico , Enfermedades Cardiovasculares/tratamiento farmacológico , Satisfacción del Paciente , Calidad de Vida , Administración Oral , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Anticoagulantes/administración & dosificación , Anticoagulantes/efectos adversos , Enfermedades Cardiovasculares/complicaciones , Niño , Estudios Transversales , Femenino , Hemorragia/inducido químicamente , Humanos , Masculino , Persona de Mediana Edad , Percepción , Calidad de la Atención de Salud , Encuestas y Cuestionarios , Trombosis/complicacionesRESUMEN
Haemoperitoneum secondary to haemorrhagic corpus luteum has been described in severe bleeding disorders such as afibrinogenaemia, type 3 von Willebrand's disease and patients under oral anticoagulation. We have studied one patient who presented three episodes of severe bleeding at ovulation, requiring surgery twice, with the diagnosis of mild von Willebrand's disease and mild storage pool deficiency. Mild von Willebrand's disease (associated with other thrombopathies or coagulopathies) should be considered in this pathology, although physicians would prefer to find a severe haemorrhagic disorder as the underlying condition in these cases.
Asunto(s)
Cuerpo Lúteo/irrigación sanguínea , Hemoperitoneo/etiología , Ovulación , Deficiencia de Almacenamiento del Pool Plaquetario/complicaciones , Enfermedades de von Willebrand/complicaciones , Abdomen Agudo/etiología , Adulto , Pruebas de Coagulación Sanguínea , Epistaxis/etiología , Femenino , Hemorragia Gingival/etiología , Hematoma/etiología , Hemoperitoneo/cirugía , Humanos , Recurrencia , Choque/etiologíaRESUMEN
The present study investigated the effect of nitric oxide (NO) on megakaryocyte (Mk) proliferation induced by thrombopoietin (TPO). Low-density mononuclear cells (MNCs) and CD34+ cells from human bone marrow (BM) were cultured in liquid medium in the presence of sodium nitroprusside (SNP) or (Z)-1-[2-(aminoethyl)-N-(2-ammonioethyl) amino] diazen-1-ium-1, 2-diolate (DETA/NO) and then stimulated with TPO. Mk number decreased in both NO donors, as identified by flow cytometry 11 to 13 days after TPO stimulation. Nitrite, cyanide, or the carrier molecule DETA failed to reproduce the inhibition caused by NO donors. When CD34+ cells were treated with DETA/NO, the inhibition of Mk growth was even more pronounced than that in MNCs. Failure of the guanosine 3',5'-cyclic monophosphate (cGMP) analog 8-bromoguanosine 3',5'-cyclic monophosphate (8-Br-cGMP) to inhibit Mk proliferation suggests that cGMP is not involved in Mk suppression mediated by NO. On the other hand, DNA analysis by flow cytometry showed that apoptosis of CD34+ cells and Mks seemed to be at least one of the mechanisms associated with the cytotoxic DETA/NO effect. Stimulation of MNCs or CD34+ cells with tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) increased endogenous NO levels and suppressed Mk growth. Treatment with NO synthesis inhibitors such as L -N(G)-monomethyl arginine (L -NMMA) or L -N(G)-nitroarginine methyl ester hydrochloride (L -NAME) partially reversed Mk growth inhibition induced by TNF-alpha and IFN-gamma, although increased NO levels returned to normal values. The results presented here strongly indicate that NO regulates the growth of Mks induced by TPO by a direct effect on both progenitors and mature Mks.
Asunto(s)
División Celular/fisiología , Megacariocitos/citología , Óxido Nítrico/fisiología , Trombopoyetina/farmacología , Antígenos CD34/inmunología , Apoptosis/fisiología , División Celular/efectos de los fármacos , Citometría de Flujo , Humanos , Megacariocitos/inmunologíaRESUMEN
BACKGROUND AND OBJECTIVES: von Willebrand's disease (vWD) is a bleeding disorder with variable clinical expression. Our aim was to classify patients with vWD and to determine the phenotype in their relatives. DESIGN AND METHODS: The types and subtypes, blood group frequency and its relevance, bleeding sites, response to the desmopressin (DDAVP) test, transfusion requirements and clinical features in type 1 and 2A families were determined in 1,885 patients. RESULTS: Our findings were: type 1: 91%, type 2A: 3.1%, severe vWD: 1.3%; type 2N: 1.6%; type low intraplatelet: 2.7%; combined 1+ 2N: 0.3%. Blood group O prevalence was 70.5%. Bleeding and transfusion requirements were not correlated to blood groups. The most frequent symptoms were: ecchymoses-hematomas and epistaxis and, in females over 13 years, also menorrhagia. Normal levels of factor VIII:C were found in 38.4% of the patients. DDAVP was infused in 567 patients with a good response in 80.6%. About 9% of our patients needed transfusion therapy. The diagnosis of von Willebrand's disease is more likely in subjects belonging to families with type 2A disease than in members of families with type 1 vWD in spite of these being symptomatic. INTERPRETATION AND CONCLUSIONS: These observations provide a good strategy to identify, classify and treat vWD patients without performing molecular assays.
Asunto(s)
Enfermedades de von Willebrand/genética , Argentina/epidemiología , Antígenos de Grupos Sanguíneos/análisis , Estudios de Cohortes , Salud de la Familia , Femenino , Hemorragia/etiología , Humanos , Masculino , Fenotipo , Prevalencia , Enfermedades de von Willebrand/sangre , Enfermedades de von Willebrand/epidemiologíaRESUMEN
Severe consumption coagulopathy has been detected in rats after Lopap (a prothrombin activator from Lonomia obliqua caterpillar bristles) infusion and in humans after accidental contact with L. obliqua bristles. However, platelet count and antithrombin (AT) levels were only modestly affected, suggesting that a different form of blood coagulation activation may be involved in this hemorrhagic syndrome. Here we describe that Lopap had no effect on aggregation of washed human platelets induced by several agonists, suggesting that it might not impair platelet function in vivo. AT was able to inhibit the amidolytic activity of thrombin generated by incubation of Lopap with prothrombin in a purified system, which may be different from that generated by the prothrombinase complex in vivo. The surface expression of both ICAM-1 and E-selectin but not of VCAM-1 was upregulated by Lopap in cultured HUVEC, suggesting that it may behave differently from other mediators, such as thrombin and tumor necrosis factor-alpha.
Asunto(s)
Plaquetas/efectos de los fármacos , Endotelio Vascular/efectos de los fármacos , Serina Endopeptidasas/farmacología , Animales , Venenos de Artrópodos/farmacología , Moléculas de Adhesión Celular/efectos de los fármacos , Moléculas de Adhesión Celular/metabolismo , Endotelio Vascular/citología , Humanos , Cinética , Lepidópteros , Agregación Plaquetaria/efectos de los fármacos , Protrombina/efectos de los fármacos , Protrombina/metabolismo , Venas Umbilicales , Regulación hacia Arriba/efectos de los fármacos , Factor de von Willebrand/efectos de los fármacos , Factor de von Willebrand/metabolismoRESUMEN
BACKGROUND AND OBJECTIVES: Difficulties in identifying the coexistence of neutralizing anti-factor VIII antibodies (anti-fVIII) and lupus anticoagulant (LA) are mainly due to the interference of LA on anti-fVIII assays. Our aim was to reveal the presence of anti-fVIII using a system that is not affected by LA. DESIGN AND METHODS: We developed an enzyme-linked immunosorbent assay (ELISA) method that uses phospholipid-free recombinant factor VIII as the antigen. A monoclonal anti-fVIII was tested as a positive control, excluding non-specific binding by using two unrelated monoclonal antibodies. The ELISA was performed on hemophilic plasmas with anti-fVIII and negative LA (n=12) or without inhibitors (n=12). Two hemophilic plasmas with LA and presumably anti-fVIII were also assayed. Positive LA (n=12) and normal (n=10) plasmas were tested as negative controls. RESULTS: All (12/12) plasmas with anti-fVIII and 5/12 hemophilic plasmas without inhibitors were positive; LA and normal plasma controls were negative. INTERPRETATION AND CONCLUSIONS: Results presented here show that LA does not interfere with the anti-fVIII ELISA: However, the assay detects both neutralizing and non-neutralizing anti-fVIII antibodies, therefore a neutralizing effect must be confirmed through functional tests.
Asunto(s)
Anticuerpos/inmunología , Factor VIII/inmunología , Hemofilia A/inmunología , Anticuerpos/sangre , Reacciones Cruzadas , Ensayo de Inmunoadsorción Enzimática , Hemofilia A/sangre , Humanos , Inhibidor de Coagulación del Lupus/inmunología , Proteínas Recombinantes/inmunología , Sensibilidad y EspecificidadRESUMEN
There is convincing evidence that cell adhesion plays an important role in cardiovascular pathology and is frequently associated to "in vivo" cellular activation. This study involves patients with mechanical heart valve replacement (MHVR patients) who have increased platelet polymorphonuclear leukocyte (PMN) reactivity. Dual-color cytometry was used to determine the expression of adhesive molecules on cellular surfaces, platelet, and PMN-bound fibrinogen as well as the presence of circulating platelet/PMN mixed-cell aggregates (MCA) in 55 MHVR patients, 49 control patients under oral anticoagulant therapy, and 22 healthy volunteers. The results demonstrated that (a) PMN from MHVR patients showed an increased PMN-bound fibrinogen (mean +/- SEM: 1,420 +/- 169 anti-fibrinogen fluorescence intensity, P= 0.0012), when compared to controls (mean +/- SEM: 747 +/- 32 anti-fibrinogen fluorescence intensity) and healthy volunteers (mean +/- SEM: 692 +/- 25 anti-fibrinogen fluorescence intensity; (b) platelet activation in MHVR patients was evidenced by the higher expression of CD62P (mean +/- SEM: 128 +/- 19 anti-CD62P fluorescence intensity, P = 0.003) compared to controls (mean +/- SEM: 65 +/- 15 and 50 +/- 10 anti CD62P fluorescence intensity) and by increased levels of platelet-bound fibrinogen (mean +/- SEM: 625 +/- 20 anti-fibrinogen fluorescence intensity, P = 0.0043 versus 496 +/- 45 and 480 +/- 30 for control patients and for healthy volunteers, respectively); and (c) the proportion of MCA in MHVR patients (15 +/- 2%) was significantly higher (P = 0.009) compared to controls (7 + 1%) and healthy volunteers (6 +/- 2%). The results indicate that the presence of stable circulating MCA represents another marker of "in vivo" PMN activation in MHVR patients.
Asunto(s)
Plaquetas/fisiología , Adhesión Celular , Prótesis Valvulares Cardíacas/efectos adversos , Neutrófilos/fisiología , Adulto , Anciano , Plaquetas/patología , Moléculas de Adhesión Celular/sangre , Femenino , Fibrinógeno/metabolismo , Citometría de Flujo , Humanos , Inmunofenotipificación , Masculino , Persona de Mediana Edad , Neutrófilos/patología , Adhesividad PlaquetariaRESUMEN
Thrombopoietin (TPO) and granulocyte colony-stimulating factor (G-CSF) may be administered together in aplastic patients. We evaluated the effect of both cytokines alone or combined on platelets and polymorphonuclear leukocytes (PMN) functional responses. TPO, G-CSF, or the combination of both cytokines, induced neither platelet nor PMN activation. TPO but not G-CSF synergized with threshold ADP concentrations to induce maximal aggregation and ATP release. The synergistic effect of TPO with ADP was not modified by the presence of G-CSF. Flow cytometry studies have shown that thrombin-induced loss of GPIb from platelet surface was significantly increased by pretreatment of platelets with TPO, G-CSF, or both cytokines. P-selectin expression induced by thrombin was augmented by TPO, but not by G-CSF. Coincubation of the cells with TPO and G-CSF did not modify the values obtained with TPO alone. Expression of CD11b on PMN surface was augmented by G-CSF or fMLP. G-CSF-treated PMN increased the effect of fMLP on CD11b expression. TPO did not modify either basal levels of CD11b or the increased expression induced by G-CSF or fMLP. Incubation of PMN with both cytokines showed no differences compared to G-CSF alone. Platelet-PMN aggregates induced by thrombin in whole blood were augmented by TPO. G-CSF alone neither synergized with thrombin nor changed the results observed with TPO. These data show that in vitro functional responses of platelets, or PMN induced by TPO or G-CSF alone, were neither further increased nor inhibited by treatment of the cells with both cytokines.
Asunto(s)
Plaquetas/efectos de los fármacos , Factor Estimulante de Colonias de Granulocitos/farmacología , Neutrófilos/efectos de los fármacos , Trombopoyetina/farmacología , Adenosina Difosfato/farmacología , Humanos , Antígeno de Macrófago-1/biosíntesis , Antígeno de Macrófago-1/efectos de los fármacos , Activación Neutrófila/efectos de los fármacos , Selectina-P/efectos de los fármacos , Activación Plaquetaria/efectos de los fármacos , Complejo GPIb-IX de Glicoproteína Plaquetaria/efectos de los fármacos , Trombina/farmacologíaRESUMEN
The number of patients under oral anticoagulant therapy has markedly increased lately, mainly due to those with chronic atrial fibrillation. Progress has been made in the control of oral anticoagulation because sensitive and calibrated commercial reagents for prothrombin time have become available. But bleeding is still a problem in these patients. In our experience, the intensity and the duration of the anticoagulant therapy are the most important risk factors for bleeding. The deviation of INR (International Normalized Ratio) can also be associated with higher risk for bleeding. The limitations of oral anticoagulant therapy include frequent laboratory controls for dose adjustment, drug interactions, narrow therapeutic range and the high variability in patient response. These limitations prompted the development of new antithrombotic agents. A number of low molecular weight active site inhibitors of thrombin are being developed and one of them is orally bioavailable, and could become an alternative to vitamin K antagonists.
Asunto(s)
Anticoagulantes/uso terapéutico , Administración Oral , Anticoagulantes/efectos adversos , Quimioterapia/tendencias , Predicción , Hemorragia/etiología , Humanos , Relación Normalizada Internacional , Tiempo de Protrombina , Factores de RiesgoAsunto(s)
Endotelio Vascular/metabolismo , Receptores de IgG/biosíntesis , Células Cultivadas , Endotelio Vascular/citología , Endotelio Vascular/efectos de los fármacos , Calor , Humanos , Inmunoglobulina G/metabolismo , Interferón gamma/farmacología , Interleucina-1/farmacología , Lipopolisacáridos/farmacología , Unión Proteica/efectos de los fármacos , Receptores de IgG/efectos de los fármacos , Receptores de IgG/metabolismo , Trombina/farmacología , Factor de Necrosis Tumoral alfa/farmacología , Venas Umbilicales/citologíaRESUMEN
We studied major bleeding complications, death related to hemorrhage, and tried to identify predisposing factors for bleeding in outpatients treated with acenocoumarol. We evaluated 811 outpatients attending a specialized anticoagulant therapy unit. The intended INR range was 3.5-4.5 for mechanical heart valve replacement (N= 384) and 2.0-3.0 for other indications (N= 427). The variability of INR for the total follow-up and the 2 months before the hemorrhage was calculated. The total follow-up was 1,963.26 years with 27,321 control tests. We observed 47 major bleeding episodes, including 2 fatal (central nervous system hemorrhages), in 37 patients. 49.5% of the patients had underlying diseases. The rate of major and fatal hemorrhage was 2.39 and 0.10 episodes per 100 patients year, respectively. Hemorrhagic complications were more frequently observed in patients with a more intense intended range (8.2% in the INR 3.5-4.5 group vs. 1.5% in the 2.0-3.0 INR group). The risk of major bleeding increased in patients with an achieved INR higher than 6 and in those with higher INR variability during follow-up. The estimated probability of bleeding also increased with time: it was 0.102% at 78 months, and at the beginning of therapy it was 0.006% and 0.007% at 1 and 4 months, respectively. The intensity of anticoagulation and the deviation of the INR from the target are the most important risk factors for bleeding in patients taking acenocoumarol. Monitoring the variability of INR can help identifying patients predisposed to bleeding. However, the screening for underlying disease should always be performed.
Asunto(s)
Acenocumarol/uso terapéutico , Anticoagulantes/administración & dosificación , Hemorragia/epidemiología , Administración Oral , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Anticoagulantes/uso terapéutico , Niño , Preescolar , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Factores de RiesgoRESUMEN
The number of patients under oral anticoagulant therapy has markedly increased lately, mainly due to those with chronic atrial fibrillation. Progress has been made in the control of oral anticoagulation because sensitive and calibrated commercial reagents for prothrombin time have become available. But bleeding is still a problem in these patients. In our experience, the intensity and the duration of the anticoagulant therapy are the most important risk factors for bleeding. The deviation of INR (International Normalized Ratio) can also be associated with higher risk for bleeding. The limitations of oral anticoagulant therapy include frequent laboratory controls for dose adjustment, drug interactions, narrow therapeutic range and the high variability in patient response. These limitations prompted the development of new antithrombotic agents. A number of low molecular weight active site inhibitors of thrombin are being developed and one of them is orally bioavailable, and could become an alternative to vitamin K antagonists.
RESUMEN
OBJECTIVE: To evaluate the outcome of pregnancy in women with mechanical heart valve prostheses in relation to the anticoagulant treatment used in the first trimester and the incidence of thrombotic and bleeding complications. METHODS: 92 pregnancies in 59 women were followed between 1986 and 1997. In 31 pregnancies, oral anticoagulants were discontinued when pregnancy was diagnosed and subcutaneous heparin was started (12 500 U every 12 hours) adjusted to prolong the adjusted partial thromboplastin time to twice the control level. In the second trimester oral anticoagulants were resumed but changed to heparin again 15 days before the expected delivery date. In 61 pregnancies oral anticoagulants were continued during the first trimester. The same regimen of heparin was used for delivery. RESULTS: Abortion or fetal losses were similar (p = 0. 5717) in women exposed to oral anticoagulants in the first trimester (13/61; 25%) compared with those who received adjusted subcutaneous heparin (6/31; 19%). Embolic episodes were more common (p = 0.0029) in women who received heparin (4.92%) compared with those on oral anticoagulants (0.33%). Embolic episodes were cerebral and transient. No valve thromboses were observed. No malformations appeared in the 71 newborns, except for one case of hydrocephalus. There were no maternal deaths secondary to thrombotic complications. The only death was the result of major bleeding after the delivery of a premature stillborn. CONCLUSIONS: Oral anticoagulants seem to be safer for the mother than adjusted subcutaneous heparin. Heparin does not offer a clear advantage over oral anticoagulation in the pregnancy outcome.
Asunto(s)
Anticoagulantes/uso terapéutico , Implantación de Prótesis de Válvulas Cardíacas , Complicaciones Cardiovasculares del Embarazo/prevención & control , Resultado del Embarazo , Tromboembolia/prevención & control , Administración Oral , Adolescente , Adulto , Válvula Aórtica , Esquema de Medicación , Femenino , Heparina/administración & dosificación , Heparina/uso terapéutico , Humanos , Inyecciones Subcutáneas , Persona de Mediana Edad , Válvula Mitral , Embarazo , Primer Trimestre del Embarazo , Tercer Trimestre del EmbarazoRESUMEN
We developed a new method for the detection of large von Willebrand factor (vWf) multimers binding to collagen and for the determination of vWf antigen (vWf:Ag) using flow cytometry. Collagen is coated on to polystyrene beads, allowing detection of found large vWf multimers. In addition, rabbit antibody against vWf is coated on to the beads allowing detection of all vWf:Ag. In plasma samples from healthy persons and patients (with type 1, 2A, 2N, or severe von Willebrand disease or hemophilia), 4 different assays were performed: vWf:Ag by immunoelectrophoresis; vWf ristocetin cofactor (vWf:RCof); CBA; and vWf:Ag based on an enzyme-linked immunosorbent assay using polystyrene beads. We assayed the flow cytometric method using 2 bead sizes. The optimal bead size was 3.136 microns. The results of CBA and vWf:Ag closely correlated with those of vWf:RCof and vWf:Ag (immunoelectrophoresis), respectively, and showed a low limit of detection. Interassay variance of cytometric methods was lower than interassay variance of traditional assays. In addition, we used the new assays to monitor desmopressin therapy.
Asunto(s)
Colágeno/metabolismo , Citometría de Flujo/métodos , Factor de von Willebrand/metabolismo , Animales , Desamino Arginina Vasopresina/uso terapéutico , Ensayo de Inmunoadsorción Enzimática , Hemofilia A/sangre , Hemofilia A/diagnóstico , Humanos , Inmunoelectroforesis , Microesferas , Peso Molecular , Poliestirenos , Unión Proteica , Conejos , Valores de Referencia , Sensibilidad y Especificidad , Enfermedades de von Willebrand/sangre , Enfermedades de von Willebrand/diagnóstico , Enfermedades de von Willebrand/tratamiento farmacológico , Factor de von Willebrand/análisis , Factor de von Willebrand/inmunologíaRESUMEN
BACKGROUND: Mechanical heart valve replacement requires lifelong anticoagulant treatment. Aspirin has proved useful in further reducing thromboembolic events when added to oral anticoagulants. However, increased (gastrointestinal) bleeding was observed at the doses previously tested for this combination in heart valve prostheses. METHODS: We performed a prospective randomized trial to compare the combination of low-intensity oral anticoagulants (international normalized ratio 2.5 to 3.5) plus aspirin (100 mg/day) (arm A) versus high-intensity oral anticoagulants alone (arm B) (international normalized ratio 3.5 to 4.5). Arm A included 258 patients and arm B 245 patients. The two groups were comparable for all baseline characteristics. RESULTS: The outcomes of the study were embolism, valve thrombosis, and major hemorrhage. The median follow-up was 23 months. The two treatments offered similar antithrombotic protection. The incidence of embolic episodes was 1.32 per 100 patient-years (95% confidence interval 0.53 to 2.7) for arm A and 1.48 per 100 patient-years (95% confidence interval 0.59 to 3.03) for arm B. Major hemorrhage occurred in 1.13 per 100 patient-years (95% confidence interval 0.41 to 2.45) for arm A and 2.33 per 100 patient-years (95% confidence interval 1.17 to 4.14) for arm B. Gastrointestinal bleeding was not increased by this combined reduced dose of aspirin and coumarin.