Diagnóstico de la enfermedad de von Willebrand / Diagnosis of von Willebrand disease

La enfermedad de von Willebrand (EVW) es el trastorno hemorrágico hereditario más común, y se caracteriza por presentar disminución de la capacidad del factor von Willebrand (FVW) de unirse a las plaquetas y al colágeno de la matriz extracelular durante la hemostasia primaria, debido a defectos cuantitativos o cualitativos. La EVW se clasifica en tres fenotipos principales: el 1 y el 3 que son trastornos cuantitativos, y el 2 que se subclasifica en 2A, 2B, 2M y 2N, y refleja los trastornos cualitativos. Para su diagnóstico son necesarios varios pasos: 1) la evaluación del historial de sangrado personal y familiar del paciente, 2) detección inicial de trastornos hemorrágicos, 3) pruebas para la detección de la EVW, 4) pruebas para la tipificación de la EVW, y 5) el análisis molecular. Tanto la subclasificación de la EVW como su diagnóstico continúan planteando desafíos importantes, motivo por el cual se realiza esta revisión, de manera que los profesionales de la salud tengan una guía que los oriente al momento de tener pacientes con algún trastorno hemorrágico que amerite descartar una EVW e implementar un tratamiento adecuado

von Willebrand disease (VWD) is the most common hereditary bleeding disorder, and is characterized by a decreased ability of the von Willebrand factor (VWF) to bind to platelets and extracellular matrix collagen during primary hemostasis, due to quantitative or qualitative defects. VWD is classified into three main phenotypes: 1 and 3, which are quantitative disorders, and 2 (2A, 2B, 2M and 2N) that reflects qualitative disorders. Several steps are necessary for its diagnosis: 1) evaluation of the patient's personal and family bleeding history, 2) initial screening tests for bleeding disorders, 3) tests for the detection of VWD, 4) tests for the classification of VWD, and 5) molecular analysis. Both the subclassification of VWD and its diagnosis continue to represent important challenges, which we aimed to describe in this review, so that health professionals have a guide to assist them when they have patients with a bleeding disorder that requires exclusion of VWD, and implementation of an appropriate treatment.

Effect of Protein Kinase A Activation on Aggregation Function of Platelets / 中国实验血液学杂志

OBJECTIVE@#To investigate the effect of protein kinase A (PKA) activation on aggregation funetion of platelets in vitro.@*METHODS@#The peripheral blood of healthy adults were collected, and the washed platelets were gained from collected peripheral blood. The washed platelets were treated with PKA activator Forskolin, then the platelet aggregation was induced by using Ristocetin, Thrombin, Collagen and ADP respectively, the platelet aggregation level was detected by the platelet aggregator.@*RESULTS@#Compared with the controls, 5 μmol/L forskolin significantly inhibited ADP and collagen-induced platelet aggregation (P＜0.001), and showed mild inhibiting effect on Thrombin-induced platelet aggregation (P＜0.05). 2.5-10 μmol/L forskolin significantly inhibited ADP and Collagen -induced platelet aggregation (P＜0.001); but not showed significantly inhibitory effects on Ristocetin-induced platelet aggregation (P＞0.05).@*CONCLUSION@#PKA activation inhibits agonists-induced platelet aggregation.

Validación de un ensayo automatizado para determinar la actividad de cofactor de ristocetina del factor von Willebrand / Validation of an automated assay to determine activity of ristocetin cofactor of von Willebrand factor / Validação de um teste automatizado para determinar a atividade de cofator de ristocetina do fator von Willebrand

La enfermedad de von Willebrand (EvW) se debe a un defecto, cuali o cuantitativo de la molécula del factor von Willebrand (VWF). Bajos niveles de VWF:Ag sugieren la EvW pero no distinguen los subtipos, por lo cual es necesario determinar también la funcionalidad del VWF para completar el diagnóstico. El método de referencia para estudiar la función del VWF es el ensayo del cofactor de ristocetina (VWF:RCo), basado en la habilidad del VWF para inducir la aglutinación de las plaquetas en presencia de ristocetina. Recientemente se han desarrollado métodos automatizados para determinar la actividad de cofactor de ristocetina. El objetivo fue evaluar el comportamiento del ensayo inmunoturbidimétrico automatizado VWF:RCo con el ensayo de actividad de VWF (VWF:Act) utilizado como screening de la EvW y con el ensayo tradicional de VWF:RCo por agregometría. La precisión intraensayo fue 3,1% y la precisión interensayo evaluada con el control normal fue de 3,2% mientras que con el control patológico se obtuvo un coeficiente de variación de 5,1%. Cuando se compararon los resultados de VWF:Act y VWF:RCo inmunoturbidimétrico en 60 pacientes, el coeficiente de correlación fue 0,96 con un bias -3,5%. En un subgrupo de 30 pacientes se comparó el VWF:Rco determinado por agregación y automatizada, y se obtuvo una correlación de 0,90 con un bias de 18,9%. Los valores de vWRCO obtenidos fueron, con un error total máximo permitido de 15%, estadísticamente comparables con aquellos determinados por el método VWF:Act y los valores de VWF:RCo obtenidos por agregometría en los pacientes estudiados.

Von Willebrand disease (VWD) is caused by a defective qualitative or quantitative von Willebrand factor (VWF) molecule. Low VWF:Ag suggests but does not distinguish VWD subtypes. Therefore, it is also necessary to determine the functionality of VWF to complete the diagnosis. The reference method to study VWF function is the ristocetin cofactor assay (VWF:RCo) based on the VWF ability to induce platelet aggregation in the presence of ristocetin. Recently, automated methods for determining the activity of ristocetin cofactor have been developed. The aim of this study is to evaluate the performance of VWF:RCo automated immunoturbidimetric assay: with VWF activity assay (VWF:Act ) used as a screening of VWD and the traditional VWF:RCo test by aggregometry. Intra-assay precision was 3.1% and interassay precision was: 3.2% in normal control and 5.1% low control: When VWF:Act and immunoturbidimetric VWF:RCo results were compared in 60 patients, the correlation coefficient was 0.96 with a -3.5% bias. In a subset of 30 patients VWF:Rco was compared, determined by aggregation and in an automated manner, yielding a correlation of 0.90 with an 18.9% bias. VWO:Rco values obtained were -with a 15% allowable total error- statistically comparable with those determined by the VWF:Act method, and the VWF:RCo values determined by aggregometry in the patients studied.

A doença de von Willebrand (DvW) ocorre devido a um defeito, qualitativo ou quantitativo da molécula do fator von Willebrand (VWF). Baixos níveis de VWF:Ag sugerem a EvW, mas não distinguem os subtipos, portanto é necessário determinar também a funcionalidade do VWF para completar o diagnóstico. O método de referência para estudar a função do VWF é o teste do cofator de ristocetina (VWF:RCo), baseado na habilidade de VWF para induzir a aglutinação das plaquetas em presença de ristocetina. Recentemente foram desenvolvidos métodos automatizados para determinar a atividade de cofator de ristocetina. O objetivo foi avaliar o comportamento do teste imunoturbidimétrico automatizado VWF:RCo com o teste de atividade de VWF (VWF:Act) utilizado como screening da EvW e com o ensaio tradicional de VWF:RCo por agregometria. A precisão intra-teste foi de 3,1% e a precisão inter-teste avaliada com o controle normal foi de 3,2% ao passo que com o controle patológico foi obtido um coeficiente de variação de 5,1%. Quando foram comparados os resultados de VWF:Act e VWF:RCo imunoturbidimétrico em 60 pacientes, o coeficiente de correlação foi de 0,96 com um Bias -3,5%. Num subgrupo de 30 pacientes se comparou o VWF:Rco determinado por agregação e automatizada, obtendo uma correlação de 0,90 com um bias de 18,9%. Os valores de VWF:Rco obtidos foram, com um erro total máximo permitido de 15%, estatisticamente comparáveis com aqueles determinados pelo método VWF:Act e os valores de VWF:RCo obtidos por agregometria nos pacientes estudados.

Validación de una técnica de actividad de factor von Willebrand que utiliza glicoproteína Ib mutada / Validation of a method based on a mutant glycoprotein Ib for von Willebrand factor activity measure / Validação de uma técnica da atividade do fator de von Willebrand que usa mutante de glicoproteína Ib

La medida de actividad del factor von Willebrand (vWF) es importante para el diagnóstico de la enfermedad de von Willebrand (vWD). El equipo Innovance®vWF Ac (Siemens Healthcare Diagnostics) utiliza un método inmunoturbidimétrico diseñado para coagulómetros Sysmex CA (Siemens). El objetivo del estudio fue desarrollar y validar la metodología del reactivo Innovance®vWF Ac para el coagulómetro ACL TOP 700 (Instrumentation Laboratory, IL) y realizar un estudio comparativo de su desempeño frente a la de la técnica vWF Activity (vWF Act, IL) y a la del cofactor de ristocetina (vWF:RCo) por agregación de transmisión de luz. Se desarrolló, calibró y validó la técnica mediante estudios de verificación de linealidad y precisión total para dos niveles de control. Se midió la actividad del vWF por los métodos Innovance®vWF Ac y vWF Act en 82 muestras consecutivas dentro del rango reportable. Para comparar métodos se utilizó la regresión de Deming. El análisis inicial de los resultados de Innovance®vWF Ac y vWF Act demostró que no eran estadísticamente comparables. Se observó un Bias negativo para Innovance®vWF Ac en muestras con vWF Act>150%. Excluyendo las mismas, se demostró que los resultados de ambas pruebas eran comparables, al igual que los de Innovance®vWF Ac y vWF:RCo en un subgrupo de 27 muestras. La adaptación del método Innovance®vWF Ac en el ACL TOP 700 fue exitosa, presentó linealidad y precisión acorde con los requerimientos de calidad del laboratorio, brindando resultados comparables a los de vWF Act y vWF:RCo en el rango de 5-150%, útil para el diagnóstico de vWD.

Measurement of vonWillebrand factor (vWF) activity is important for the diagnosis of von Willebrand disease (vWD). Innovance®vWF Ac assay was designed to Sysmex CA (Siemens) coagulometer. The aim of the study was to develop and validate a method for Innovance®vWF Ac in the ACL TOP 700 (Instrumentation Laboratory) coagulometer and to compare its performance against vWF Activity assay (Instrumentation Laboratory, vWF Act) and Ristocetin cofactor assay by light transmission aggregation (vWF:RCo). The method was designed, calibrated and validated through verification of linearity and total precision studies at two levels of control plasmas. vWF activity was measured by Innovance®vWF Ac and vWF Act in 82 consecutive samples with vWF Act values within the reportable range. For method comparison, Deming regression was used. The initial analysis of results showed that they were not statistically comparable with a negative Bias with Innovance®vWF Ac in samples with vWF Act>150%. Excluding these samples, Deming regression curve showed that both tests gave statistically comparable results, and also did Innovance®vWF Ac and vWF:RCo in a subset of 27 samples. The adaptation of the Innovance®vWF Ac method on the ACL TOP 700 coagulometer was successful, it met the quality requirements of the laboratory for linearity and accuracy, providing comparable results to vWF Act and vWF:RCo in the of 5-150% range, useful for vWD diagnosis.

Medir a atividade do fator von Willebrand (vWF) é importante para o diagnóstico da doença de von Willebrand (vWD). A equipe Innovance®vWF Ac (Siemens Healthcare Diagnostics) utiliza um método imunoturbidimétrico projetado para coagulômetros Sysmex CA (Siemens). O objetivo do estudo foi desenvolver e validar a metodologia do reagente Innovance®vWF Ac para o coagulômetro ACL TOP 700 (laboratório de instrumentação, IL) e realizar um estudo comparativo do seu desempenho perante a técnica vWF Activity (vWF Act, IL) e a do cofator de ristocetina (vWF:RCo) por agregação de transmissão de luz. A técnica foi projetada, calibrada e validada através de testes de verificação da linearidade e total precisão para dois níveis de controle. Foi mensurada a atividade do vWF pelos métodos Innovance®vWF Ac e vWF Act em 82 amostras consecutivas dentro do intervalo reportável. Para comparar métodos foi utilizada a regressão de Deming. A análise inicial dos resultados da Innovance®vWF Ac e vWF Act demonstrou que eles não eram estatisticamente comparáveis. Observou-se um viés negativo para Innovance®vWF Ac em amostras com vWF Act> 150%. Excluindo as mesmas, foi demonstrado que os resultados de ambos os testes eram comparáveis, do mesmo modo que os Innovance®vWF Ac e vWF:RCo num subgrupo de 27 amostras. A adaptação do método Innovance®vWF Ac no ACL TOP 700 foi bem-sucedida, apresentou linearidade e precisão conforme os requisitos de qualidade do laboratório, fornecendo resultados comparáveis aos vWF Act e vWF:RCo na faixa de 5-150%, útil para o diagnóstico da vWD.

The caspase-3 inhibitor (peptide Z-DEVD-FMK) affects the survival and function of platelets in platelet concentrate during storage

BACKGROUND: Although apoptosis occurs in nucleated cells, studies show that this event also occurs in some anucleated cells such as platelets. During storage of platelets, the viability of platelets decreased, storage lesions were observed, and cells underwent apoptosis. We investigated the effects of caspase-3 inhibitor on the survival and function of platelets after different periods of storage. METHODS: Platelet concentrates were obtained from the Iranian Blood Transfusion Organization in plastic blood bags. Caspase-3 inhibitor (Z-DEVD-FMK) was added to the bags. These bags along with control bags to which no inhibitor was added were stored in a shaking incubator at 22degrees C for 7 days. The effects of Z-DEVD-FMK on the functionality of platelets were analyzed by assessing their ability to bind to von Willebrand factor (vWF) and to aggregate in the presence of arachidonic acid and ristocetin. Cell survival was surveyed by MTT assay. RESULTS: At day 4 of storage, ristocetin-induced platelet aggregation was significantly higher in the inhibitor-treated (test) than in control samples; the difference was not significant at day 7. There was no significant difference in arachidonic acid-induced platelet aggregation between test and control samples. However, at day 7 of storage, the binding of platelets to vWF was significantly higher in test than in control samples. The MTT assay revealed significantly higher viability in test than in control samples at both days of study. CONCLUSION: Treatment of platelets with caspase-3 inhibitor could increase their functionality and survival.

Utilidad clínica de la agregometría plaquetaria / Clinical utility of platelet aggregometry

Resumen: La acción de las plaquetas en la hemostasia primaria comprende la adhesión a losvasos sanguíneos afectados, la activación, la secreción del contenido granular, y posteriormente,la agregación plaquetaria para la formación del tapón hemostático primario. Bajo las condicionesfisiológicas de flujo vascular, estos procesos requieren la acción sinérgica de varias proteínasy receptores plaquetarios, como también de agonistas que inducen la activación plaquetaria.Por ello, las mutaciones de los genes que codifican para moléculas y receptores de superficieimplicados en estos procesos darán origen a desórdenes hemorrágicos como la enfermedad devon Willebrand, la trombastenia de Glanzmann, el síndrome de Bernard Soulier y la deficienciade gránulos plaquetarios, entre otros. El diagnóstico de estas enfermedades se realiza medianteensayos de función plaquetaria que simulan los procesos fisiológicos de activación, adhesión,liberación del contenido granular y agregación. Una de las pruebas de función plaquetaria másutilizada es la agregometría. En este artículo de revisión se describe la utilidad de esta prueba parael diagnóstico de desórdenes hemorrágicos hereditarios y del síndrome de la plaqueta pegajosa,un desorden trombótico hereditario caracterizado por hiperagregabilidad. Adicionalmente, se revisa el fundamento de esta prueba, las condiciones preanalíticas, analíticas y posaanaliticas, analiticas y poanaliticas las indicaciones las contraindicaciones y la interpetación de los resultados.

Abstract: The role of platelets in primary hemostasis involves their adherence to sites of vessel injury, activation, secretion of platelet granule content, and finally, aggregation to form the primaryhemostatic plug. Under physiologic conditions of vascular flow, these processes require thesynergistic action of several proteins and platelet receptors, and also the action of physiologicalagonists that stimulate the activation of the platelets. As a result, hereditary mutations of genescodifying for molecules and surface receptors implied in primary hemostasis will be expressedas hemorrhagic disorders, including von Willebrand disease, Glanzmann thrombasthenia,Bernard Soulier syndrome, storage pool diseases, among others. The diagnosis of these diseases is possible through platelet function assays that resemble the physiological processesof activation, adhesion, release of granule content, and aggregation. Platelet aggregometry isone of the most frequently used tests. This review article intends to describe the utility of plateletaggregometry for the diagnosis of hereditary hemostatic disorders and sticky platelet syndrome, a hereditary thrombotic disorder characterized by increased platelet aggregability. In addition, the fundamentals of the test, the pre-analytical, analytical and post-analytical conditions, the test indications, contraindications and results interpretation are discussed.

Clinical Effects of Additional Cilostazol Administration After Drug-Eluting Stent Insertion

BACKGROUND AND OBJECTIVES: Cilostazol, a selective inhibitor of phosphodiesterase III (PDE III), prevents inactivation of the intracellular second messenger cyclic adenosine monophosphate (cAMP) and irreversibly inhibits platelet aggregation and vasodilation. Hence, we performed this prospective randomized study to evaluate the clinical effects of additional cilostazol administration in patients receiving dual antiplatelet therapy after drug-eluting stent (DES) insertion. SUBJECTS AND METHODS: Between December 2003 and June 2006, we enrolled a total 603 consecutive patients who underwent successful percutaneous coronary intervention (PCI) with DES insertion at Dong-A University Hospital. Study patients received dual antiplatelet therapy (aspirin and clopidogrel, n=301) for at least six months or dual antiplatelet therapy (six months) combined with cilostazol medication for one month (triple therapy, n=302) after PCI. We investigated the incidence of major adverse cardiac events (MACE) at one month and six months after the initiation of medical therapy. MACE was defined as a composite of death, myocardial infarction (MI), stent thrombosis, and target lesion revascularization (TLR). Platelet function was evaluated in 66 patients (dual therapy group, n=40; triple therapy group, n=26) using a Chrono-Log platelet aggregometer and the VerifyNow P2Y12 assay system. RESULTS: The MACE rate was 0.66% in the triple therapy group (death only, 0.67%) and 1.67% in the dual therapy group (death, 0.67%; MI, 0.67%; stent thrombosis, 0.99%; TLR, 0.99%) at one month after PCI (p=0.087). At six months, there were no differences in the MACE rate between the two groups (triple group vs. dual group=2.65% vs. 3.99%, p=0.864). In laboratory tests, platelet aggregation induced by agonists of ADP (27.92+/-13.04% vs. 40.9+/-15.78%, p=0.0008), collagen (13.73+/-6.95% vs. 27.43+/-14.87%, p=0.03), and epinephrine (10.38+/-7.82% vs. 15.5+/-10.45%, p=0.0000) were lower in the triple therapy group versus the dual therapy group. However, platelet aggregation induced by agonists of arachidonic acid (3.23+/-1.07% vs. 3.78+/-2.12%, p=0.23) and ristocetin (29.19+/-35.55% vs. 44.78+/-32.65%, p=0.07) and aspirin reaction unit (412.96+/-96.25 vs. 427.93+/-76.24, p=0.48) measured by VerifyNow were not different in the triple group versus the dual group. CONCLUSION: Additional administration of cilostazol did not decrease the MACE rate when compared to dual therapy six months after PCI in patients with DES.

Prevalence and spectrum of von Willebrand disease from western India.

BACKGROUND AND OBJECTIVE: von Willebrand disease (VWD) is one of the most common inherited bleeding disorders in the west. Limited studies from India showed a prevalence of approximately 10 per cent of VWD among the cases with hereditary bleeding disorders. VWD remains an underdiagnosed entity in India. The prevalence of different subtypes of VWD is also not known which is essential for a proper management of these cases. The present study was thus undertaken to know the prevalence of VWD and its various subtypes in the western part of our country. METHODS: A total of 796 consecutive patients presented with various bleeding manifestations were analysed. The initial screening and confirmation tests for the diagnosis of VWD included bleeding time (BT), screening coagulation tests i.e., prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT), factor VIII: C assay, ristocetin-induced platelet aggregation (RIPA) and VWF antigen (VWF:Ag) estimations. VWF multimer analysis, ristocetin cofactor activity (RCOF), VWF collagen binding assay (VWF: CBA), factor VIII : VWF binding assay were also done to classify and subtype these cases. RESULTS: The patients were subtyped as per the International Society of Thrombosis and Haemostasis (ISTH) criteria. Of the 796 patients screened, 58 were diagnosed as VWD. Of the 15 families with a positive family history of bleeding, 26 additional cases were diagnosed as VWD. Majority of the patients were type 3 (59.5%) with severe clinical manifestations, about 18 per cent of type 1 VWD patients were detected in this group while the prevalence of the qualitative variants of VWD i.e., type 2 VWD was found to be 19 per cent and the prevalence of various subtypes were type 2A (9.52%), type 2B (4.76%), type 2M (1.2%), type 2N (3.6%). INTERPRETATION AND CONCLUSION: The high prevalence of type 3 and a low prevalence of type 1 VWD which is in contrast to the western reports, suggests the low awareness of the disease as also the underdiagnosis of the mild cases in our country.

Comparison of the Activities of Platelets with Different Cryopreservation Methods / 대한혈액학회지

BACKGROUND: The limit and the optimal method of the cryopreservation of platelets have not been determined. Moreover, the functional changes platelets after cryopreservation were not clearly defined. This study was conducted to determine the limit and optimal method for cryopreservation of platelet concentrates. METHODS: We compared the recovery, expression of membrane GpIb, GpIIb/IIIa, and aggregatory function of the platelets preserved in three different conditions. Platelet samples were collected from four healthy volunteer donors by apheresis, and placed in 22degrees C agitator for standard preservation. For cryopreservation, after treating 5% DMSO, platelets were either inserted directly in -80degrees C freezer or in liquid nitrogen after computer-controlled rate freezing. After storage for 5 days, 1 week, 2 weeks, 3 weeks, 4 weeks, and 12 weeks, platelets were thawed and analyzed for the evaluation of in vitro functions. RESULTS: Platelets preserved at 22degrees C or cryopreserved with each condition displayed equivalent recovery (90%). With each cryopreservation procedures, platelets showed moderate loss of GpIb and retained more than 90% of GpIIb/IIIa in comparison with fresh platelets. At the third week, loss of GpIb in the directly frozen platelets was augmented compared with those of controlled rate frozen group. The aggregatory response to ristocetin began to decrease drastically after storage for 5 days in platelets frozen by each procedures and to less than 5% at 12 weeks of storage. However, controlled rate frozen platelets retained more aggregatory response to ristocetin and surface GpIb expression than those of directly frozen platelets at 3, 4, 12 weeks of storage. CONCLUSION: This study showed the possibility of moderate preservation of in vitro functions of frozen-thawed platelets after 12 weeks of storage compared with those of the liquid stored 5-day old platelets.

Subtypes of von Willebrand Disease Based on vWF Multimer Analysis in Korea / 대한소아혈액종양학회지

PURPOSE: von Willebrand disease is a common inherited bleeding disorder characterized by high degree of variable clinical presentation due to either quantitative or qualitative defects in von Willebrand factor. Its incidence in Korea is not well studied while that in western countries is extensively studied. METHODS: We classified 16 cases of vWD from 14 unrelated families based on vWF antigen, ristocetin cofactor activity, factor VIII activity and vWF multimeric patterns analysed by agarose gel electrophoresis, according to a revised classification by ISTH. RESULTS: There were 12 cases (75%) of type 1 vWD or 2M/2N with normal multimeric pattern, 3 cases (18.75%) of type 2 vWD lacking high molecular weight multimers and only 1 case of type 3 vWD with no multimers. CONCLUSION: The proportion of each vWD subtype in Korea is similar to that in western countries, however, accurate diagnosis based on ristocetin induced platelet aggregation test, factor VIII binding assay and molecular genetic diagnosis seems to be necessary for a more complete classification of vWD.

Effect of Low-Dose Aspirin Therapy on Platelet Aggregation in Kawasaki Disease

PURPOSE: Aspirin(acetylsalicylic acid) has been used to treat unstable angina and acute myocardial infarction in adults and Kawasaki disease in children. The antithrombotic effect of aspirin was attributed to its ability to inhibit platelet aggregation by inhibiting platelet cyclooxygenase, which leads to decreased thromboxane synthesis. The purpose of this study was to evaluate the effect on the platelet aggregation by low dose aspirin in Kawasaki patients and to learn the side effects of low-dose aspirin. METHODS: Fifty patients with Kawasaki disease who were treated with low-dose aspirin, and 22 normal children were studied from Jan. 1996 to Dec. 1997. The platelet count, bleeding time, clotting time, platelet aggregation test(induced by ADP, epinephrine, collagen and ristocetin) and blood aspirin level by colorimetric method were checked. RESULTS: The platelet count, bleeding time, and clotting time in the patient group were not significantly different from the control group. The mean maximum platelet aggregation was 54.4+/-12.8% induced by ADP, 15.9+/-11.7% by epinephrine, 55.5+/-23.8% by collagen, 52.6+/-32.2% by ristocetin in the patient group. It was significantly lower than the control group(P<0.05). The mean blood aspirin level in the patient group was 5.4+/-3.7mg/dl. Side effects of low-dose aspirin were bruise, epistaxis and hematuria. CONCLUSION: Low-dose aspirin therapy in patients with Kawasaki disease inhibited platelet aggregation, but attention would be needed because of the tendency to bleed in these patients. Further investigations should be focused on the subject such as the onset of the maximal antiplatelet effect and time needed for the recovery of platelet function.

Nuclear Hyperploidy of Megakaryocytes and Platelet Aggregation Test in Essential Thrombocythemia / 대한혈액학회지

BACKGROUND: Essential thrombocythemia (ET) is a rare chronic myeloproliferative disorder characterized by an extremely high platelet count in the circulating blood and abnormal proliferation of the megakaryocytes in bone marrow, resulting in splenomegaly, thromboembolic or hemorrhagic complications. We studied the presence of nuclear hyperploidy of the megakaryocytes in bone marrow, the presence of abnormal response to the individual reagent on platelet aggregation test, and its clinical implication. METHODS: We analyzed the 43 cases of ET at the Asan Medical Center between January, 1989 and March, 1999. The Polycythemia Vera Study Group criteria were used to diagnose ET. RESULTS: Nuclear hyperploidy was observed at 43 cases (100%). Platelet aggregation test was done at 32 (74.4%) cases, of which 27 (84.4%) cases showed abnormal response to more than one reagent, 16 (50%) cases to more than two reagents. Abnormal response to epinephrine and collagen was most common, but 5 cases showed normal response. By individual reagent, 1 (3%) cases to adenosine diphosphate, 1 (3%) case to ristocetin, 22 (69%) cases to epinephrine, 19 (59%) cases to collagen showed abnormal response. CONCLUSION: We observe that nuclear hyperploidy of the megakaryocyts and abnormal response on platelet aggregation test are frequent in ET in this study.

Prevalence of Impaired Platelet Responsiveness to Epinephrine in Healthy Subjects / 대한혈액학회지

BACKGROUND: The purpose of this study is to investigate the prevalence of impaired platelet responsiveness to epinephrine in healthy subjects. Also, we compared the platelet aggregability in response to various agonists in normal population. METHODS: A total of 156 healthy subjects aged 21 to 57 years were investigated for the evidence of impaired responsiveness to epinephrine. Aggregometer PACKS-4 (Platelet Aggregation Chromogenic Kinetic System-4, Helena, Beaumont, USA) was used for platelet function test. Aggregating agonists (Helena Haemostasis Systems, UK) used in the study were consisted of ADP (10 micrometer), collagen (10 microgram/mL), epinephrine (300 micrometer) and ristocetin (1500 microgram/mL). Population showing platelet aggregability with more than 60% activity was classified as normal group, while aggregability with less than 20% as impaired responsiveness. RESULTS: Of 156 healthy subjects, 20.5% (32/156) showed impaired responsiveness, while 33.9% (53/156) revealed decreased aggregability with the activity of less than 60% to epinephrine. The mean of maximal percent aggregating activity for collagen was 90.5+/-11.4% and that of epinephrine was 66.5+/-34.4%. The mean aggregation activity (84.4+/-11.8%) for ADP in subjects showing normal response to epinephrine was significantly higher, compared with that (65.7+/-16.2%) of impaired responsiveness group to epinephrine (P<0.01). CONCLUSION: Impaired responsiveness to epinephrine, which is observed in healthy subjects, appears to be a kind of normal variant reaction. And this abnormality is not considered to be associated with any evident bleeding disorders.

A Case of TypeI Glanzmann's Thrombasthenia Diagnosed by Flow Cytometry

Glanzmann's thrombasthenia is a rare autosomal recessive hemorrhagic disorder of platelet function with missing or abnormal platelet plasma membrane glycoprotein IIb-IIIa, which functions as a receptor for fibrinogen. We have experienced a case of thrombasthenia in a 6-year-old female whose chief complaints were easy bruising, frequent epistaxis, arthralgia and swelling of the right ankle joint. Bleeding time was prolonged in the presence of normal platelet levels and the platelet aggregation test showed lack of aggregation after exposure to ADP, epinephrine and collagen, but showed an aggregation response to ristocetin. Platelet analysis by flow cytometry is a successful alternative rapid diagnostic technique for Glanzmann's thrombasthenia patients as well as for carriers of this disease. Flow cytometry technique provides an effective tool for investigating platelet function defects caused by altered expression or deficiency of platelet surface proteins.

A Case of TypeI Glanzmann's Thrombasthenia Diagnosed by Flow Cytometry

Glanzmann's thrombasthenia is a rare autosomal recessive hemorrhagic disorder of platelet function with missing or abnormal platelet plasma membrane glycoprotein IIb-IIIa, which functions as a receptor for fibrinogen. We have experienced a case of thrombasthenia in a 6-year-old female whose chief complaints were easy bruising, frequent epistaxis, arthralgia and swelling of the right ankle joint. Bleeding time was prolonged in the presence of normal platelet levels and the platelet aggregation test showed lack of aggregation after exposure to ADP, epinephrine and collagen, but showed an aggregation response to ristocetin. Platelet analysis by flow cytometry is a successful alternative rapid diagnostic technique for Glanzmann's thrombasthenia patients as well as for carriers of this disease. Flow cytometry technique provides an effective tool for investigating platelet function defects caused by altered expression or deficiency of platelet surface proteins.

Platelet Aggregability in the Patients with Peripheral Vestibulopathy / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Circulatory disturbance to vestibular organ has been regarded as one of the causes that bring about vertigo, and alteration of the platelet function is known to be an important factor inducing circulatory deficit. This study was designed to evaluate platelet aggregability in the patients with peripheral vestibulopathy, and to evaluate difference according to duration of illness. MATERIALS AND METHODS: Platelet aggregation tests to adenosine diphosphate (ADP), ristocetin, epinephrine and collagen were performed in 10 normal subjects and 15 patients with peripheral vestibulopathy. Maximum aggregation rates from aggregation curves were compared between the two groups, and also between the two groups of patients who had different duration of illness. RESULTS: In the patient group, platelet aggregations to ADP, ristocetin and collagen were increased compared to normal subjects and significant differences were found in aggregations to ADP and ristocetin. However, there was no significant difference according to different duration of illness in the patient group. CONCLUSION: These results suggest that platelet aggregability is increased in the patients with peripheral vestibulopathy, and duration of illness does not affect platelet aggregability.

Aluminum induces lipid peroxidation and aggregation of human blood platelets

Aluminum (Al3+) intoxication is thought to play a major role in the development of Alzheimer's disease and in certain pathologic manifestations arising from long-term hemodialysis. Although the metal does not present redox capacity, it can stimulate tissue lipid peroxidation in animal models. Furthermore, in vitro studies have revealed that the fluoroaluminate complex induces diacyglycerol formation, 43-kDa protein phosphorylation and aggregation. Based on these observations, we postulated that Al3+-induced blood platelet aggregation was mediated by lipid peroxidation. Using chemiluminescence (CL) of luminol as an index of total lipid peroxidation capacity, we established a correlation between lipid peroxidation capacity and platelet aggregation. Al3+ (20-100 muM) stimulated CL production by human blood platelets as well as their aggregation. Incubation of the platelets with the antioxidants nor-dihydroguaiaretic acid (NDGA) (100 muM) and n-propyl gallate (NPG) (100 muM), inhibitors of the lipoxygenase pathway, completely prevented CL and platelet aggregation. Acetyl salicylic acid (ASA) (100 muM), an inhibitor of the cyclooxygenase pathway, was a weaker inhibitor of both events. These findings suggest that Al3+ stimulates lipid peroxidation and the lipoxygenase pathway in human blood platelets thereby causing their aggregation.

Evaluation of the Status of Frozen Thawed Platelet Concentrations By using 6% Dimethyl Sulfoxide Cryopreservation method / 대한수혈학회지

We tried to analyze the status of 10 units of frozen thawed apheresis platelet concentration by 6% DMSO method for the evaluation of practical applicability. The platelet concentrations were transferred to PL-732(Baxter, USA) cryopreservation bag, and DMSO is added to those bag at slow rate until expected final 6% concentration is achieved, thereafter those were directly placed to -80 degrees C refrigerator for freezing. Someday later from I week to 1 month, those were thawed at 37 degrees C water bath, and then washed by same volume of ABO matched plasma. In the course of cryopreservation, about 7% of platelets were lost and the mean recovery rate of platelet was 93% compared with those of unfrozen status. LDH, the values of platelet lysis, and pH were within normal limits, whereas platelet aggregation test shows decreased aggregation to collagen and ristocetine compared with those of unfrozen status(p<0.05) but they were clinically acceptable. We suggest that the frozen platelets may be useful in a some clinical situation such as hematologic malignancy and solid tumor by autologous transfusion.

Estudio de la actividad procoagulante de las plaquetas en el síndrome de Bernard Soulier / Procoagulant activity of platelets study in the Bernard Soulier's syndrome

En el síndrome de Bernard soulier (SBS) han sido demostradas alteraciones específicas que dan lugar a un trastorno en la adhesividad plaquetaria. También se le han atribuido otros defectos que condicionan una alteración en el actividad procoagulante de sus mismas plaquetas, los cuales no han logrado definirse satisfactoriamente. En el presente trabajo se estduió el efecto procoagulante de las plaquetas, en cuatro pacientes con SBS, comparándolo con los resultados en controles sanos y enfermos trombocitopénica, para tal fin se efectuaron modificaciones en el cosumo de protrombina (CP) y tiempo de recalcificación del plasma, para evaluar el efecto de la trombocitopenia y el de plasmas con deficiencias intensas y específicas de factores de coagulación V, VIII y XI sobre el mecanismo procoagulante de las plaquetas con SBS. Los resultados observados difieren de los informados por otros investigadores, pues no se detectó ningún defecto en la actividad procoagulante en las plaquetas de los pacientes con SBS, considerando que su actividad procoagulante es normal, o bien, que existan variante de dicho síndrome