Púrpura trombocitopênica trombótica: o papel do fator von Willebrand e da ADAMTS13 Thrombotic thrombocytopenic purpura: the role of von Willebrand factor and ADAMTS13

A púrpura trombocitopênica trombótica (PTT) instala-se de modo abrupto e é caracterizada pela oclusão difusa de arteríolas e capilares da microcirculação, levando à isquemia de tecidos. A oclusão é causada por microtrombos compostos basicamente de plaquetas e fator von Willebrand (FvW). O FvW é uma glicoproteína de estrutura multimérica sintetizada exclusivamente por células endoteliais e megacariócitos. Este fator promove a adesão das plaquetas ao endotélio lesado, participa do processo de agregação plaquetária e é a proteína carreadora do fator VIII na circulação. Em condições fisiológicas, os grandes multímeros do FvW encontram-se dentro das células endoteliais e nas plaquetas e não estão presentes no plasma. Tão logo estes grandes multímeros são liberados da célula endotelial, são clivados e removidos da circulação pela enzima ADAMTS13 (A Desintegrin And Metalloprotease with eight Thrombo Spondin-1-like). A deficiência funcional ou quantitativa de ADAMTS13 resulta no acúmulo de grandes multímeros de FvW no plasma, propiciando a agregação das plaquetas e oclusão difusa das arteríolas e capilares. A maioria dos casos de PTT está associada à deficiência da ADAMTS13 e já estão disponíveis no mercado internacional conjuntos diagnósticos para a determinação dos níveis de antígenos desta enzima, da de sua atividade e dos anticorpos anti-ADAMTS13. A avaliação laboratorial da ADAMTS13 parece constituir um avanço para o diagnóstico precoce da PTT. No entanto, a interpretação dos resultados exige cautela e um conhecimento do princípio do método, bem como das etapas das reações envolvidas.Thrombotic thrombocytopenic purpura (TTP) starts abruptly and is characterized by diffuse occlusion of microcirculation arterioles and capillaries, leading to ischemia of tissues. Occlusion is caused by microscopic clots primarily composed of platelets and von Willebrand factor (VWF). VWF is a multimeric glycoprotein synthesized exclusively by endothelial cells and megakaryocytes. This factor promotes adhesion of platelets to injured endothelium, participates in the process of platelet aggregation and is the carrier protein of factor VIII in the circulation. In physiological conditions, large VWF multimers are present in endothelial cells and platelets and are not present in plasma. As soon as these large multimers are released from the endothelial cell, they are cleaved and removed from circulation by the ADAMTS13 enzyme. A quantitative or functional deficiency of ADAMTS13 results in the accumulation of large VWF multimers in the plasma and may result in the aggregation of platelets and diffuse occlusion of arterioles and capillaries. Most cases of PTT are associated with ADAMTS13 deficiency. The levels of antigens, activity and antibodies of MTS13 can be evaluated using internationally manufactured kits. The laboratory evaluation of ADAMTS13 appears to be a useful tool for the early diagnosis of PTT. However, interpretation of the results requires caution, as well as knowledge of the principles of the method and the steps of the reactions involved

Tissue factor and tissue factor pathway inhibitor in women with a past history of preeclampsia: implication for a hypercoagulable state postpregnancy

Preeclampsia (P-EC) is a multisystem disorder of pregnancy whose cause and pathogenesis remain poorly understood. However, abnormal haemostasis and endothelial dysfunction are thought to be implicated. Women with a past medical history of P-EC have a baseline hypercoagulable state postpregnancy. The aim of this study is to examine the relationship between tissue factor (TF) and TF pathway inhibitor (TFPI) in women who have had P-EC within the last 3 years (more than 6 months postpartum) and their normal counterparts. Blood specimens were collected from women known to have had P-EC within the last 3 years (n?=?26) and aged-matched healthy women without past history of P-EC in previous pregnancy (n?=?26). Plasma TF and TFPI levels were measured using ELISAs. Women who have had P-EC showed increased TF levels compared with their normal counterparts, whereas TFPI levels were reduced. Neither parameter differed significantly when the groups were tested against each other. Interestingly, the TF/TFPI ratio was significantly increased (P?=?0.024) when the two groups were compared. In summary, there was a trend towards increased TF and reduced TFPI levels in the P-EC group. Such a tendency was not statistically significant. However, the TF/TFPI ratio was significantly increased when the groups were compared. Our findings suggest an imbalance between TF/TFPI levels in women with past history of P-EC postpregnancy. This may contribute to the development of maternal hypercoagulable states and may predispose women with a history of P-EC to cardiovascular risks later in life

Púrpura trombocitopênica trombótica: o papel do fator von Willebrand e da ADAMTS13

A púrpura trombocitopênica trombótica (PTT) instala-se de modo abrupto e é caracterizada pela oclusão difusa de arteríolas e capilares da microcirculação, levando à isquemia de tecidos. A oclusão é causada por microtrombos compostos basicamente de plaquetas e fator von Willebrand (FvW). O FvW é uma glicoproteína de estrutura multimérica sintetizada exclusivamente por células endoteliais e megacariócitos. Este fator promove a adesão das plaquetas ao endotélio lesado, participa do processo de agregação plaquetária e é a proteína carreadora do fator VIII na circulação. Em condições fisiológicas, os grandes multímeros do FvW encontram-se dentro das células endoteliais e nas plaquetas e não estão presentes no plasma. Tão logo estes grandes multímeros são liberados da célula endotelial, são clivados e removidos da circulação pela enzima ADAMTS13 (A Desintegrin And Metalloprotease with eight Thrombo Spondin-1-like). A deficiência funcional ou quantitativa de ADAMTS13 resulta no acúmulo de grandes multímeros de FvW no plasma, propiciando a agregação das plaquetas e oclusão difusa das arteríolas e capilares. A maioria dos casos de PTT está associada à deficiência da ADAMTS13 e já estão disponíveis no mercado internacional conjuntos diagnósticos para a determinação dos níveis de antígenos desta enzima, da de sua atividade e dos anticorpos anti-ADAMTS13. A avaliação laboratorial da ADAMTS13 parece constituir um avanço para o diagnóstico precoce da PTT. No entanto, a interpretação dos resultados exige cautela e um conhecimento do princípio do método, bem como das etapas das reações envolvidas

Índice de anisocitose eritrocitária (RDW): diferenciação das anemias microcíticas e hipocrômicas Red blood cell distribution width (RDW): differentiation of microcytic and hypochromic anemias

A anemia ferropriva, talassemia menor e anemia de doença crônica são as anemias microcíticas e hipocrômicas mais comuns em nosso meio. O diagnóstico diferencial das referidas anemias é de grande importância clínica; contudo, muitas vezes é complexo em virtude de concomitância de doenças, além de demandar tempo e apresentar custos significativos. Com o propósito de conferir maior simplicidade e eficiência ao diagnóstico diferencial destas anemias, o uso de índices derivados de modernos contadores automáticos tem sido sugerido. Entre estes, pode ser citado o índice de anisocitose eritrocitária (RDW), que indica o grau de variabilidade do tamanho das hemácias. Neste estudo, o poder de discriminação deste índice quanto ao tipo de anemia microcítica e hipocrômica foi avaliado em um grupo de 159 pacientes sabidamente portadores de um quadro de anemia causado por deficiência de ferro, beta talassemia menor ou uma anemia de doença crônica. Não foi observada diferença significativa para o RDW entre os três grupos de anemias microcíticas, indicando não ser este índice uma ferramenta útil para a diferenciação entre anemia ferropriva, beta talassemia menor e anemia de doença crônica.<br>Iron deficiency anemia, the thalassemia trait and chronic disease anemia are the most common microcytic and hypochromic anemias in the Brazilian population. Differential diagnosis of these anemias is of great clinical importance however, frequently, it is complex due to coexistence of diseases, as well as being time consuming and expensive. In order to simplify and increase efficiently of checking the differential diagnoses of these anemias, the use of indexes derived from modern blood cell counters has been suggested. Among them, is the index called red blood cell distribution width which indicates the variability in red blood cell size. In this study, the discriminative power of the red blood cell distribution width in differentiating microcytic and hypochromic anemias was evaluated in a group of 159 patients diagnosed as carriers of either iron deficiency anemia, &#946;-thalassemia minor or chronic disease anemia. No difference was found for the red blood cell distribution width among the three groups of microcytic and hypochromic anemias indicating that this index is not a useful tool to distinguish among iron deficiency, &#946;-thalassemia minor and chronic disease anemia

O papel do RDW, da morfologia eritrocitária e de parâmetros plaquetários na diferenciação entre anemias microcíticas e hipocrômicas The role of RDW, erythrocyte morphology and platelet parameters in the differentiation between microcytic and hypochromic anemias

As anemias microcíticas e hipocrômicas atingem grande parcela da população mundial. Entre estas, significativa porcentagem de casos se deve à deficiência do ferro, enquanto em algumas regiões a frequência de talassemia menor se torna importante. Por outro lado, a anemia de doença crônica é a causa mais comum de anemia em pacientes hospitalizados. O diagnóstico diferencial destas doenças é clinicamente importante, e é atualmente realizado através dos exames padrão ouro envolvendo a avaliação do metabolismo do ferro e dosagem de HbA2. Embora dotados de grande utilidade, estes testes podem apresentar uma metodologia mais demorada e onerosa que, em casos de concomitância de doenças, comuns na prática clínica, não conseguem proporcionar um correto diagnóstico. Na tentativa de otimizar e direcionar o diagnóstico destas anemias, o uso de alguns parâmetros derivados dos modernos contadores automáticos tem sido sugerido. Neste estudo, o papel do RDW, parâmetros plaquetários (número de plaquetas, PDW, VPM) e morfologia eritrocitária como parâmetros diferenciadores, foi avaliado em um grupo de 159 pacientes portadores de anemia microcítica e hipocrômica devido à deficiência do ferro, anemia de doença crônica e talassemia beta menor, comprovado pelos exames padrão ouro. Foi possível observar que o RDW não se mostrou um bom discriminante, enquanto o índice plaquetário PDW pode ser um parâmetro auxiliar no diagnóstico diferencial das anemias microcíticas e hipocrômicas. Com relação às alterações morfológicas dos eritrócitos, o pontilhado basófilo foi um achado bastante comum apenas em pacientes portadores de talassemia beta menor, com indícios de potencial utilidade na elucidação de casos de microcitose.Microcytic and hypochromic anemias affect many people worldwide. A significant percentage of cases are due to iron deficiency, while in certain regions the frequency of thalassemia minor is important. On the other hand, anemia of chronic disease is the most common cause of anemia in hospitalized patients. Differential diagnosis between these anemias, currently established by using gold standard tests involving evaluation of iron metabolism and measurement of HbA2, is of clinical importance. Although very useful, these tests are time consuming and onerous. In cases of concomitant diseases, a common finding in the clinical practice, these tests are unable to provide a correct diagnosis. In an attempt to optimize diagnosis of these anemias, the use of some parameters derived from modern automated blood count analyzers has been suggested. In this study, the role of RDW, platelet parameters (platelet number, PDW, MPV) and erythrocyte morphology as differentiating parameters were evaluated in a group of 159 patients diagnosed as carriers of microcytic or hypochromic anemias due to iron deficiency, anemia of chronic disease and &#946;-thalassemia minor, as confirmed by gold standard tests. The RDW did not prove to be a good discriminator, while the platelet index, PDW, may be helpful in the differential diagnosis of microcytic and hypochromic anemias. Regarding the red cell morphologic alterations, basophilic stippling was a quite common finding just in patients with &#946;-thalassemia minor, suggesting it to be a potential marker for elucidating cases of microcytosis

Evaluation of the interference of platelets in reticulocyte counting by flow cytometry using thiazole orange

ABSTRACT Introduction: The reticulocyte count by flow cytometry (FC) - an automated counting method - can present errors due to the presence of interfering factors, contributing to a slight increase in results. However, automated methods have large advantages over the manual method, taken as reference, what justifies efforts to improve their quality. Objective: Evaluate platelet interference with the reticulocyte count by FC, using thiazole orange (TO) (FC/TO). Materials and methods: The method of reticulocyte count by FC/TO and a modified automated equivalent method, which excluded CD61-positive cells (platelets) from analysis (FC/TO/MOD), were compared to the manual method. Conclusion: Results were analyzed according to the recommendations of the Clinical and Laboratory Standards Institute (CLSI) to assess interchangeability between the methods, by linear regression analysis and paired t-test. The exclusion of interfering fragments from result analysis by the modified method produced results in closer proximity to those of the reference method

Soluble endoglin, transforming growth factor-Beta 1 and soluble tumor necrosis factor alpha receptors in different clinical manifestations of preeclampsia.

BACKGROUND: Despite intensive research, the etiopathogenesis of preeclampsia (PE) remains uncertain. Inflammatory and angiogenic factors are thought to play considerable roles in this disease. The objective of this study was to investigate the association between soluble endoglin (sEng), transforming growth factor beta-1 (TGF-β1) and tumor necrosis factor alpha soluble receptors (sTNF-Rs) and the clinical manifestations of PE. METHODS: Plasma levels of sEng, TGF-β1 and sTNF-Rs were determined by ELISA in 23 non-pregnant, 21 normotensive pregnant and 43 PE women. PE women were stratified into subgroups according to the severity [mild (n = 12) and severe (n = 31)] and onset-time of the disease [early (n = 19) and late (n = 24)]. RESULTS: Pregnancy was associated with higher levels of sEng, sTNF-R1 and sTNF-R2 than the non-pregnant state. Moreover, PE women had higher levels of sEng and sTNF-R1 than normotensive pregnant women. No difference was found in TGF-β1 levels, comparing the three study groups. Late PE had higher levels of sTNF-R1 and sTNF-R2 than early PE. No significant differences were found in sEng and TGF-β1 comparing early and late PE. sEng levels were higher in severe PE than in mild PE and no difference was found for TGF-β1, sTNF-R1 and sTNF-R2 levels. There was a positive correlation among sEng, TNF-R1 and sTNF-2 levels. Logistic regression analysis revealed that primiparity and sEng levels are independently associated with the development of PE. Furthermore, sEng levels are independently associated with the disease severity. CONCLUSIONS: These results suggest that pregnancy is a condition associated with higher levels of anti-angiogenic and pro-inflammatory factors than the non-pregnant state and that PE is associated with an imbalance of these factors in the maternal circulation