Estudios de agregación plaquetaria como endofenotipo de las alteraciones hereditarias de la fibra colágena / Platelet aggregation studies as an endophenotype of hereditary disorders of collagen fiber

Introducción: Las plaquetas contribuyen a la hemostasia y la interrupción heredada o adquirida; en sus procesos bioquímicos pueden alterar la función plaquetaria. Estos trastornos de agregación se han asociado a enfermedades genéticas con afectación del tejido conectivo como el síndrome Ehlers-Danlos, cuyo diagnóstico diferencial con el espectro de hipermovilidad articular resulta difícil clínica y molecularmente. Estas entidades con afectación en las fibras colágenas y diferente repercusión clínica precisan diferenciales en su diagnóstico clínico. Métodos: Se revisaron 353 historias clínicas de pacientes atendidos en el Servicio de Genética del Hospital Pediátrico William Soler desde septiembre del 2009 al 2012, con diagnóstico de hipermovilidad articular por criterios de Beighton y de Ehlers-Danlos según Villefranche (1997). Se incluyó a los pacientes de 5-18 años con resultados documentados del estudio de agregación plaquetaria, valorados por especialistas en hematología. Resultados: Se encontraron trastornos de agregación plaquetaria en 79 de 86 pacientes (92 por ciento). En 7 casos con hipermovilidad de 65 con este diagnóstico (10 por ciento), los resultados fueron negativos. Los 21 con síndrome Ehlers-Danlos tuvieron afectaciones con los fosfolípidos plaquetarios. La hipermovilidad articular estuvo asociada a la combinación difosfato de adenosina (ADP)-epinefrina y el Ehlers-Danlos a la combinación ADP-epinefrina-colágeno-fosfolípidos. Conclusiones: Los pacientes con hipermovilidad articular mostraron asociación a defectos de liberación de gránulos con agonistas como el ADP-epinefrina y los Ehlers-Danlos con la disponibilidad de los fosfolípidos, relacionados con el cambio de forma plaquetaria. Este resultado puede ser una herramienta para conocer el endofenotipo funcional plaquetario como elemento diferencial en los trastornos de la fibra colágena(AU)

Introduction: Platelets contribute to hemostasis and inherited or acquired interruption; in its biochemical processes it can alter platelet function. These aggregation disorders have been associated with genetic diseases with connective tissue involvement such as Ehlers-Danlos syndrome, whose differential diagnosis with the spectrum of joint hypermobility is clinically and molecularly difficult. These entities with involvement of the collagen fibers and different clinical repercussions require differentials in their clinical diagnosis. Methods: 353 medical records of patients attended in the Genetics service of the William Soler Pediatric Hospital from September 2009 to 2012, with a diagnosis of joint hypermobility by Beighton and Ehlers-Danlos criteria according to Villefranche (1997) were reviewed. Patients aged 5-18 years were included with documented results of the platelet aggregation study, assessed by specialists in hematology. Results: Platelet aggregation disorders were found in 79 of 86 patients (92 percent). In 7 cases with hypermobility of 65 with this diagnosis (10 percent), the results were negative. The 21 with Ehlers-Danlos syndrome had affectations with platelet phospholipids. Joint hypermobility was associated with the combination adenosine diphosphate (ADP) -epinephrine and the Ehlers-Danlos with the combination ADP-epinephrine-collagen-phospholipids. Conclusions: Patients with joint hypermobility showed an association to granule release defects with agonists such as ADP-epinephrine and Ehlers-Danlos with the availability of phospholipids, related to platelet shape change. This result can be a tool to know the platelet functional endophenotype as a differential element in collagen fiber disorders(AU)

Low triiodothyronine syndrome is associated with platelet function in patients with nephrotic syndrome

SUMMARY OBJECTIVE The objective of this study was to investigate the effects of low triiodothyronine syndrome (LT3S) on platelet function and clotting factors in patients with nephrotic syndrome(NS). METHODS Patients with primary nephrotic syndrome were divided into two groups, normal thyroid function (group A) and LT3S (group B), based on whether they had LT3S or not. Healthy subjects were selected as the control group (group C). Blood coagulation function was detected in each group. The platelet activation function (CD62P, CD63) was determined by flow cytometry. The platelet aggregation rate was detected by an optical method using adenosine diphosphate and arachidonic acid as inducers. RESULTS The proportion of primary nephrotic syndrome with LT3S was 23.2% (69/298). Compared with group C, group A had higher CD62P and PAgTADP, and group B had higher CD62P, CD63, PAgTAA, and PAgTADP; the difference was statistically significant (all P < 0.05). There was no significant difference in renal pathology between group A and group B (X2 = 4.957, P = 0.421). Compared with group A, the 24-hour urine protein, CD63, PAgTAA, and PAgTADP were higher in group B, and APTT and Alb were lower. The difference was statistically significant (P < 0.05). Logistic regression analysis showed that LT3S was associated with CD36 (OR: 3.516; 95% CI: 1.742~8.186; P = 0.004) and PAgTAA (OR: 0.442; 95% CI: 1.001~1.251; P = 0.037). CONCLUSION NS patients are prone to LT3S. Patients with LT3S may have abnormal platelet activation and increase of platelet aggregation.

RESUMO OBJETIVO O objetivo deste estudo foi investigar os efeitos da síndrome do baixo triiodotironina (LT3S) na função plaquetária e nos fatores de coagulação em pacientes com síndrome nefrótica (SN). MÉTODOS Pacientes com síndrome nefrótica primária foram divididos em dois grupos, função tireoidiana normal (grupo A) e LT3S (grupo B), com base na presença ou não de LT3S. Indivíduos saudáveis foram selecionados como grupo de controle (grupo C). A função de coagulação do sangue foi analisada em cada grupo. A função de ativação plaquetária (CD62P, CD63) foi determinada por citometria de fluxo. A taxa de agregação plaquetária foi detectada por um método óptico usando adenosina difosfato e ácido araquidônico como indutores. RESULTADOS A proporção de síndrome nefrótica primária com LT3S foi de 23,2% (69/298). Em comparação com o grupo C, o grupo A apresentou níveis mais altos de CD62P e PAgTADP, e o grupo B apresentou maiores CD62P, CD63, PAgTAA e PAgTADP; a diferença teve significância estatística (P < 0,05). Não houve diferença significativa na patologia renal entre o grupo A e o grupo B (X2 = 4,957, P = 0,421). Em comparação com o grupo A, a proteína em urina de 24 horas, CD63, PAgTAA e PAgTADP foram maiores no grupo B, já APTT e Alb foram mais baixos. A diferença apresentou significância estatística (P < 0,05). A análise de regressão logística mostrou uma associação entre LT3S e CD36 (OR: 3,516; 95% IC: 1,742~8,186; P = 0,004) e PAgTAA (OR: 0,442; 95% IC: 1,001~1,251; P = 0,037). CONCLUSÃO Pacientes com síndrome nefrótica estão propensos à síndrome do baixo triiodotironina (LT3S). Pacientes com LT3S podem ter ativação plaquetária anormal e aumento da agregação plaquetária.

Platelet function, coagulation and fibrinolysis in patients with previous coronary and cerebrovascular ischemic events

OBJECTIVES: Ischemic stroke (IS) or transient ischemic attack (TIA) history is present in 4-17% of patients with coronary artery disease (CAD). This subgroup of patients is at high risk for both ischemic and bleeding events. The aim of this study was to determine the role of platelet aggregability, coagulation and endogenous fibrinolysis in patients with CAD and previous IS or TIA. METHODS: A prospective case-control study that included 140 stable CAD patients divided into two groups: the CASE group (those with a previous IS/TIA, n=70) and the CONTROL group (those without a previous IS/TIA, n=70). Platelet aggregability (VerifyNow Aspirin® and VerifyNow P2Y12®), coagulation (fibrinogen and thromboelastography by Reorox®) and endogenous fibrinolysis (D dimer and plasminogen activator inhibitor-1) were evaluated. RESULTS: Patients in the CASE group presented significantly higher systolic blood pressure levels (135.84±16.09 vs 123.68±16.11, p<0.01), significantly more previous CABG (25.71% vs 10%, p=0.015) and significantly higher calcium channel blocker usage (42.86% vs 24.29%, p=0.02) than those in the control group. In the adjusted models, low triglyceride values, low hemoglobin values and higher systolic blood pressure were significantly associated with previous IS/TIA (CASE group). Most importantly, platelet aggregability, coagulation and fibrinolysis tests were not independently associated with previous cerebrovascular ischemic events (CASE group). CONCLUSION: Platelet aggregability, coagulation and endogenous fibrinolysis showed similar results among CAD patients with and without previous IS/TIA. Therefore, it remains necessary to identify other targets to explain the higher bleeding risk presented by these patients.

Intervalos de referencia para agregación plaquetaria en individuos sanos / Platelet aggregation reference interval for healthy individuals / Intervalos de referência para agregação plaquetária

La agregación por transmisión de luz (ATL) es el método más usado por laboratorios clínicos y de investigación para evaluar la función plaquetaria y es considerado actualmente el estándar de oro; no obstante, la ATL aún no es un método estandarizado, pese a los esfuerzos de organismos internacionales como la International Society of Thrombosis and Hemostasis (ISTH). Organismos regulatorios recomiendan que cada laboratorio clínico determine e informe sus intervalos de referencia (IR) para cada agonista que utiliza. Se presenta los IR de este laboratorio en la determinación de agregación plaquetaria mediante ALT utilizando adenosin difosfato (ADP), colágeno y adrenalina como agonistas. Para ello se diseñó un estudio de corte transversal sobre una muestra a conveniencia de voluntarios(as) aparentemente sanos; se usó un agregómetro óptico y se emplearon los siguientes agonistas y concentraciones finales: ADP 5 µM, colágeno 2 µM y adrenalina 10 µM. Se definió IR como los percentiles 2,5 y 97,5 (P2,5 y P97,5) del Porcentaje de Agregación Plaquetaria Máxima APM%. Participaron 63 individuos, rango de edad 18 a 66 años, 79,4% sexo femenino. Los valores de APM% fueron: ADP P2,5=49% y P97,5=87%; colágeno P2,5=43% y P97,5=86%; adrenalina P2,5=42% y P97,5=85%. Atendiendo a recomendaciones internacionalmente aceptadas, se presentan los IR de APM (%) por el método ATL en este laboratorio (ASCARDIO, Barquisimeto, Venezuela), lo que permite al clínico basar sus decisiones en evidencia válida y pertinente.

Platelet aggregation tests by means of light transmission (LTA), the current gold standard, are the most commonly used methods used to evaluate platelet function at clinical and research laboratories. However, LTA has not been determinastandardized despite the work from international organizations such as the International Society of Thrombosis and Homeostasis (ISTH). Regulatory agencies recommend that each clinical laboratory establishes and informs its own Reference Internal (RI) for all agonists they use. RI are presented for our laboratory using the following agonists: diphosphate (ADP), collagen y adrenaline and the pertaining methodology. To assess our RI for platelet aggregation tests by LTA, a cross-sectional study was designed with a convenience sample of healthy volunteer men and women using an optical aggregometer with the following agonist and final concentration: adenosine diphosphate (ADP) 5 µM, collagen 2 µM and adrenaline 10 µM. The RIs were defined as Percentiles 2.5 (P2,5) and 97.5 (P97.5) of the percentage of maximal aggregation (%MA). 63 subjects participate, age range 18 to 66,79.4% were female. The IR for %MA were: ADP P2,5=49% and P97.5=87%; collagen P2,5=43% and P97.5=86%; adrenaline P2,5=42% and P97.5=85%. In agreement with international accepted recommendation guidelines, RIs for the %MA values were presented by LTA done in our clinical laboratory (ASCARDIO, Barquisimeto, Lara State, Venezuela), that allows physicians to base their clinical decision process on valid and pertinent information.

A agregometria por transmissão de luz (ATL) é o método mais utilizado pelos laboratórios clínicos e de pesquisa para avaliar a função plaquetária e é atualmente considerada o padrão-ouro; no entanto, a ATL ainda não é um método padronizado, apesar dos esforços das agências internacionais como a International Society of Thrombosis and Hemostasis (ISTH). Agências reguladoras recomendam que cada laboratório clínico determine e comunique seus intervalos de referência (IR) para cada agonista utilizado. São apresentados o IR de nosso laboratório para determinar a agregação plaquetária através de ALT usando Difosfato de Adenosina (ADP), Colágeno e Adrenalina como agonistas. Para isso foi elaborado um estudo de corte transversal em uma amostra de conveniência de voluntários(as) aparentemente saudáveis , foi usado agregômetro ótico e foram utilizados os seguintes agonistas e concentrações finais: 5µ M ADP, Colágeno 2µM e Adrenalina 10µM. Definiu-se o IR com os percentis 2,5 e 97.5 (P2,5 e P97.5) do Percentual de Agregação Plaquetária Máxima APM%. Participaram 63 indivíduos, na faixa etária 18-66 anos, 79,4% do sexo feminino. Os valores de APM% foram: ADPP2,5=49% e P97.5=87%; Colágeno P2,5=43% e P99,5=86%, Adrenalina P2,5=42% e P97.5=85%. Atendendo às recomendações aceitas internacionalmente, apresentam-se os IR de APM% pelo método ATL em nosso laboratório (ASCARDIO, Barquisimeto, Venezuela), o que permite ao médico basear as suas decisões em evidências válidas e pertinentes.

El síndrome de las plaquetas pegajosas y su diagnóstico en el laboratorio / The sticky platelet syndrome and its diagnosis in the laboratory

El síndrome de las plaquetas pegajosas (SPP) es un trastorno plaquetario autosómico dominante considerado como una de las causas más frecuentes de eventos trombóticos, tanto arteriales como venosos. Este síndrome supone trastornos en la agregación de las plaquetas caracterizados por su incremento anormal. El mecanismo patogénico no se conoce; su existencia puede determinarse con las pruebas de agregación y adhesión plaquetarias. Tampoco se conoce su prevalencia, pero hay datos que sugieren que es frecuente. Algunos investigadores plantean que es responsable del 23 por ciento de las trombosis arteriales inexplicables y del 14 por ciento de las venosas, en las que no es posible identificar una causa. Se presenta una breve revisión acerca de la información disponible sobre el síndrome de las plaquetas pegajosas y su trascendencia en la salud. En Cuba existen pocos reportes de la evaluación clínica de pacientes con esta afección, por lo que resulta necesario realizar estudios más profundos para establecer la magnitud de la enfermedad

The sticky platelet syndrome (SPS) is an autosomal dominant platelet disorder considered as one of the most common causes of thrombotic events, both arterial and venous. This syndrome involves disturbances in platelet aggregation characterized by abnormal increase. The pathogenic mechanism is not known. Its existence can be determined by platelet aggregation and platelet adhesion tests. Its prevalence is also unknown, but evidence suggests that it is common. Some researchers argue that it is responsible for 23 percent of unexplained arterial thrombosis and 14 percent of the vein thrombosis, in which is not possible to identify a cause. Here a brief review on the available information on the sticky platelet syndrome and its importance in health is shown. In Cuba there are few reports of the clinical evaluation of patients with this condition, so further study to determine the extent of the disease is needed

Señales purinérgicas / Purinergic signals

En la última década se ha aportado clara evidencia de que tanto nucleósidos como nucleótidos de adenina y uridina pueden funcionar como factores de señalización extracelular. Su acción es mediada por dos tipos principales de receptores de superficie denominados purinérgicos. Los receptores P1 se activan por adenosina, y son todos metabotrópicos, mientras que los receptores de nucleótidos (ATP, ADP, UTP y UDP) y nucleótidos-azúcares (UDP-glucosa y UDP-galactosa) pueden ser metabotrópicos (P2Y) o ionotrópicos (P2X). La importancia y complejidad de este sistema de señalización se evidencia por la diversidad de mecanismos de liberación de nucleótidos al medio extracelular y por la distribución ubicua de varios grupos de ectonucleotidasas capaces de catalizar la degradación y conversión de nucleótidos. Hasta el momento se han descrito y clonado una veintena de estos receptores que modulan una variedad de respuestas, como el impulso nervioso, la respuesta inflamatoria, la secreción de insulina, la regulación del tono vascular y la percepción del dolor. En la presente revisión se describen las características estructurales y farmacológicas de los receptores purinérgicos y se analiza la interacción dinámica entre estos receptores, los nucleósidos y nucleótidos, y las ectonucleotidasas, con especial atención a la dinámica de la agregación plaquetaria, la respuesta inmune y la hidratación de las mucosas respiratorias.

In the last decade evidence accumulated that nucleosides and nucleotides of both uridine and adenine can act as extracellular signaling factors. Their action is mediated by two main types of surface receptors commonly known as purinergic. P1 receptors are metabotropic and activated by adenosine, whereas receptors for nucleotides (ATP, ADP, UTP and UDP) and nucleotide-sugars (UDP-glucose and UDP-galactose) can be either metabotropic (P2Y) or ionotropic (P2X). The importance and complexity of this signaling system is evidenced by various mechanisms of nucleotide release, as well as by the ibiquitous distribution of various types of ectonucleotidases which catalyze and convert extracellular nucleotides. Up to now about twenty receptors have been cloned and found to modulate the nerve impulse, inflammatory response, insuline secretion, the regulation of the vascular tone and nociception, among other processes. In the present review we describe the main structural and pharmacological features of purinergic receptors, and analyze how the dynamic interaction between these receptors, nucleotides and nucleosides, and ectonucleotidases modulate several biological responses. Particular focus is given to platelet aggregation and thrombus formation, the immune response and the hydration of the mucosal linings of the respiratory tract.

Changes in the level of cytosolic calcium, nitric oxide and nitric oxide synthase activity during platelet aggregation: an in vitro study in platelets from normal subjects and those with cirrhosis.

Variceal bleeding due to abnormal platelet function is a well-known complication of cirrhosis. Nitric oxide-related stress has been implicated in the pathogenesis of liver cirrhosis.In the present investigation,we evaluated the level of platelet aggregation and concomitant changes in the level of platelet cytosolic calcium (Ca2+), nitric oxide (NO) and NO synthase (NOS) activity in liver cirrhosis.The aim of the present study was to investigate whether the production of NO by NOS and level of cytosolic Ca2+ influence the aggregation of platelets in patients with cirrhosis of the liver.Agonist-induced aggregation and the simultaneous changes in the level of cytosolic Ca2+, NO and NOS were monitored in platelets of patients with cirrhosis.Platelet aggregation was also measured in the presence of the eNOS inhibitor,diphenylene iodinium chloride (DIC).The level of agonist-induced platelet aggregation was significantly low in the platelets of patients with cirrhosis compared with that in platelets from normal subjects.During the course of platelet aggregation,concomitant elevation in the level of cytosolic Ca2+ was observed in normal samples,whereas the elevation was not significant in platelets of patients with cirrhosis.A parallel increase was observed in the levels of NO and NOS activity.In the presence of the eNOS inhibitor,platelet aggregation was enhanced and accompanied by an elevated calcium level.The inhibition of platelet aggregation in liver cirrhosis might be partly due to greater NO formation by eNOS.Defective Ca2+ release from the internal stores to the cytosol may account for inhibition of aggregation of platelets in cirrhosis.The NO-related defective aggregation of platelets in patients with cirrhosis found in our study is of clinical importance,and the underlying mechanism of such changes suggests a possible therapeutic strategy with cell-specific NO blockers.

Efecto antitrombótico, una característica poco conocida de las frutas y hortalizas / Antithrombotic effect, a not well known characteristic of fruits and vegetables

Cardiovascular diseases (CVD) are the leading cause of death in the world. Several risk factors for CVD, such as lipid disorders, hypertension and diabetes mellitus, are influenced by food. It is well known that fruits and vegetables contain antioxidants and its adequate consumption reduces cardiovascular risk. However, its antithrombotic effect (antiplatelet agent, anticoagulant and fibrinolytic) is little known. This review briefly describes these effects, both in vivo and in vitro, and the possible mechanisms that could explain this effect. Fruits such as black grape, pineapple, strawberry and kiwi show this effect. Among the vegetables that have antiaggregatory effect are garlic, onions, welsh onions, tomatoes and melons. On the other hand, the anticoagulant effect has only been found in fruits like pineapple, and among the vegetables in garlic and onions. The fibrinolytic effect has been described in fruits like kiwi and pineapple, and in vegetables such as garlic, onions and soybeans. Some fruits (pineapple and kiwi) and vegetables (onion and garlic) have more than one antithrombotic effect so their regular consumption certainly protects from CVD. We have begun the study, initially in vitro, of the potential antithrombotic effect of fruits and vegetables in the Maule Region. It is necessary to increase our domestic consumption and export of fruits and vegetables, both to improve the health of the population and the economy. The reasons above stated describe the importance of the contribution of knowledge due to the fact that antioxidant effects are less known.

Las enfermedades cardiovasculares (ECV) son la principal causa de mortalidad en el mundo. Varios de los factores de riesgo de las ECV, como dislipidemias, hipertensión arterial y diabetes mellitus, son influenciados por la alimentación. Es conocido que las frutas y hortalizas contienen antioxidantes, y que su consumo en una cantidad adecuada disminuye el riesgo cardiovascular. Sin embargo, su efecto antitrombótico (antiagregante plaquetario, anticoagulante y fibrinolítico) es poco conocido. En esta revisión se describen brevemente dichos efectos, tanto in vitro como in vivo, y los posibles mecanismos que podrían explicar éstos. En cuanto al efecto antiagregante plaquetario, entre las frutas que poseen dicha característica se incluyen uva negra, piña, frutilla y kiwi. Entre las hortalizas en que se ha descrito efecto antiagregante están el ajo, la cebolla, el cebollín, el tomate y el melón. Por su parte, el efecto anticoagulante, entre las frutas, sólo se ha encontrado en la piña, y entre las hortalizas en ajos y cebollas. El efecto fibrinolítico se ha descrito en frutas como el kiwi y la piña, y hortalizas como el ajo, las cebollas y la soya. Algunas frutas (piña y kiwi) y hortalizas (ajo y cebollas) presentan más de un efecto antitrombótico por lo que seguramente su consumo regular protege de las ECV. Nosotros hemos iniciado el estudio, por lo pronto in vitro, del posible efecto antitrombótico de frutas y hortalizas de la Región del Maule. Siendo necesario aumentar el consumo interno y las exportaciones de frutas y hortalizas, tanto para mejorar la salud de la población como desde el punto de vista económico, parece relevante contribuir al conocimiento de los efectos aquí descritos, los que son menos conocidos que el efecto antioxidante.

effect of dexmedetomidine on hemodynamics, platelet aggregation and intraoperative blood loss under sevoflurane anesthesia during total hip arthroplasty

Background: sevoflurane is suggested to exert platelet anti-aggregation effect. Dexmedetomidine which is nowadays progressively used as anesthetic sparing was demonstrated experimentally to impair platelet aggregation. The purpose of the present work was to study the effect of addition of dexmedetomidine to both anesthetics on blood loss and platelet aggregation in total hip arthroplasty [THA] patients

Methods: we prospectively studied thirty adult ASA I-III patients, who were randomly allocated into two groups [15 patients each]. Group [S] received sevoflurane, while group [SD] received sevoflurane anesthesia, with dexmedetomidine infused perioperatively as an adjunct to anesthesia. Hemodynarnics [HR and MAP], bleeding time, platelet count, intraoperative blood loss and platelet aggregation induced by ADP, Adrenaline and Collagen were assessed

Results: there was no statistically significant difference between the two groups as regards the platelet count or bleeding time. Blood loss was found to be statistically significant under sevoflurane/Dexmedetomidine anesthesia, with no clinical deterioration of bleeding time or effect on blood loss. Intraoperative platelet aggregation was found to be impaired under both techniques, though more statistically significant in the Dexmedetomidine group. Dexmedetomimne still exerted inhibition of platelet aggregation 3 hours after anesthetic offset although much less inhibition was observed and limited to Adrenaline induced aggregation

Conclusion: in patients undergone THA, the present study showed that platelet aggregation was markedly depressed with the combination of Dexmedetomidine [as a loading dose of 1micro g/kg/over 20 minutes, then continued at a dose of 0.2- 0.5 micro g/kg/hour] and inhaled anesthetic sevoflurane [1-2 vol. %] which was less significant under sevoflurane only, although clinical deterioration of bleeding time or blood loss was not observed, and this may be related to the relative reduction in blood pressure and heart rate under sevoflurane anesthesia and the more reduction under dexmedetomidine/sevoflurane anesthesia

Niveles de citoquinas megacariocitopoyéticas en pacientes con trombocitemia esencial y su relación con características clínicas y bioquímicas / Megakaryopoietic cytokine levels in patients with essential thrombocythemia and their relationship with clinical and biochemical features

La megacariocitopoyesis y la producción de plaquetas están regidas por factores de transcripción y citoquinas presentes en el microambiente medular. La trombocitemia esencial (TE) es una enfermedad mieloproliferativa crónica caracterizada por aumento del recuento de plaquetas e hiperplasia megacariocítica. En el presente trabajo se evaluaron los niveles de las citoquinas que participan en el desarrollo megacariocítico en plasma de pacientes con TE que se encontraban sin tratamiento y los de trombopoyetina (TPO) antes y durante el tratamiento con anagrelide. Las determinaciones se realizaron por técnica de ELISA. Dentro de las citoquinas involucradas en la etapa de proliferación, los niveles de interleuquina 3 (IL-3) se encontraron aumentados en los pacientes (p=0.0383) respecto al grupo control. Los niveles de factor estimulante de colonias granulocito-macrofágico y stem cell factor fueron normales. Dentro de las citoquinas con acción sobre la maduración megacariocítica, tanto la interleuquina 6 como la interleuquina 11 y la eritropoyetina estuvieron normales. Los niveles de TPO antes del tratamiento no difirieron del grupo control y durante el tratamiento aumentaron de manera no significativa. Los pacientes que presentaron agregación espontánea tuvieron niveles más altos de TPO que los que no lo hicieron (p=0.049). Los niveles de las citoquinas no tuvieron relación con ninguno de los parámetros clínicos ni de laboratorio evaluados. El aumento de los niveles de IL-3 podría contribuir al incremento en la proliferación megacariocítica en este grupo. La presencia simultánea de niveles más altos de TPO y trombocitosis sería un factor predisponente para la ocurrencia de agregación espontánea en los pacientes con TE

Megakaryopoiesis and platelet production are driven by transcription factors and cytokines present in bone marrow environment. Essential thrombocythemia (ET) is a chronic myeloproliferative disorder characterized by high platelet count and megakaryocytic hyperplasia. In the present work we evaluated plasmatic levels of cytokines involved in megakaryocytic development in a group of patients with ET that were not on treatment, as well as thrombopoietin (TPO) levels before and during anagrelide treatment. The assays were carried out using ELISA techniques. Among the cytokines mainly involved in proliferation of megakaryocytic progenitors, interleukin 3 (IL-3) levels were found increased in patients compared to normal controls (p=0.0383). Granulocyte-macrophage colony stimulating factor and stem cell factor levels were normal. Interleukin 6, as well as interleukin 11 and erythropoietin (EPO), cytokines mainly related to megakaryocytic maturation, were normal. Plasma TPO levels before treatment were within the normal range and increased during treatment but the difference was not statistically significant. Patients who displayed spontaneous platelet aggregation had higher plasma TPO levels compared to those who did not (p=0.049). We did not find any relationship between cytokine levels and clinical or laboratory parameters. The high IL-3 levels seen in some patients with ET could contribute to megakaryocytic proliferation. The simultaneous occurrence of higher TPO levels and elevated platelet count could be a predisposing factor for the development of spontaneous platelet aggregation in ET patients

Involvement of throm box aneA2 and tyrosine kinase in the synergistic interaction of platelet activating factor and calcium ionophore A23187 in human platelet aggregation

The present study was carried out to examine the mechanisms of the synergistic interaction of PAF and A23187 mediated platelet aggregation. We found that platelet aggregation mediated by subthreshold concentrations of PAF (5 nM) and A23187 (1 micrometer) was inhibited by PAF receptor blocker (WEB 2086, IC50=0.65 micrometer) and calcium channel blockers, diltiazem (IC50=13 micrometer) and verapamil (IC50=18 micrometer). Pretreatment of platelets with PAF and A23187 induced rise in intracellular calcium and this effect was also blocked by verapamil. While examining the role of the down stream signaling pathways, we found that platelet aggregation induced by the co-addition of PAF and A23187 was also inhibited by low concentrations of phospholipase C (PLC) inhibitor (U73122; IC50 = 10 micrometer), a cyclooxygenase inhibitor (indomethacin; IC50=0.2 micrometer) and inhibitor of TLCK, herbimycin A with IC50 value of 5 micrometer. The effect was also inhibited by a specific TXA2 receptor antagonist, SQ 29548 with very low IC50 value of 0.05 micrometer. However, the inhibitors of MAP kinase, PD98059 and protein kinase C, chelerythrine had no effect on PAF and A23187-induced platelet aggregation. These data suggest that the synergism between PAF and A23187 in platelet aggregation involves activation of thromboxane and tyrosine kinase pathways.

Factores de señalización: pilares fundamentales en la regeneración ósea / Signaling factors: fundamental pillars in bone regeneration

El objetivo de este estudio es que el lector se familiarice con la biología ósea y con los aportes que ha realizado la ciencia en cuanto a regeneración ósea a partir de componentes orgánicos del propio paciente como los factores de señalización. Hoy en día, a partir de biología molecular y bioingeniería se obtienen factores de crecimiento a través de recombinaciones del DNA con el fin de generar órdenes de inducción en mecanismos biológicos óseos. La terapéutica con factores de crecimiento es una técnica específica para casos específicos

Thrombohaemorrhagic balance in diabetes mellitus.

Diabetes changes the thrombohaemorrhagic balance which exists in healthy flowing blood. This change predisposes a diabetic patient to various thrombo-embolic conditions, leading to increased mortality and morbidity of these patients. Increase in certain coagulation factors like factors XII, XI, VIII, fibrinogen and VWF, decreased fibrinolysis, increased platelet aggregation, endothelial cell dysfunction coupled with increased blood viscosity and decreased red cell deformability are some of the changes that contribute to increased thrombo-embolic incidence in this disease.

The activation of platelet aggregation by human cholangiocarcinoma cells is mediated through thrombin receptor.

Tumor cell induced platelet aggregation (TCIPA) played an importance role in early state of thrombosis in cancer patients. In addition, TCIPA was recognized as one important step in metastatic cascade. Cholangiocarcinoma, one of the most common cancers in the north-eastern part of Thailand, associated with thrombosis was reported. The authors investigated the effects of cholangiocarcinoma cells on platelet function as measured by platelet aggregation. Primary human cholangiocarcinoma (HuCCA) cells were established in our laboratory. Cells were cultured as standard techniques and grown to confluence until used, after which cells were replaced with fresh medium (Dulbeco Modified Eargle's Medium, DMEM) without serum for 24, 48 and 72 h. Then, the conditioned medium (CM) was collected. CM (24, 48 and 72 h) from HuCCA failed to induce platelet aggregation, whereas, HuCCA pellets induced platelet aggregation and potentiated platelet aggregation induced by submaximal concentration of thrombin. Interestingly, platelet aggregation induced by HuCCA was inhibited by hirudin (thrombin receptor antagonist; 10, 20 and 40 U) in a dose dependent manner. Thus, cholangiocarcinoma cells can induce platelet aggregation in a direct tumor cell-platelet contact via thrombin receptor. Therefore, the use of antiplatelet agents especially via thrombin receptors may help to prevent TCIPA or metastasis by CCA.

Alteración de la función plaquetaria en pediatría / Disorder of platelet function in pediatrics

Un motivo de consulta frecuente en pediatría es el sangramiento mucocutáneo que tanto asusta a los padres y cuidadores de niños. El sangramiento mucocutáneo denota una alteración de la interacción de las plaquetas con la pared vascular, también denominada hemostasia primaria. Sin olvidarnos que una alteración leve de la hemostasia secundaria también puede manifestarse como hemorragria mucocutánea. Entre las alteraciónes más frecuentes de la hemostasia primaria de carácter hereditario, encontramos la enfermedad de von Willebrand y las alteraciones de la función plaquetaria. Una de las dificultades técnicas que existen en relación al diagnóstico de estas alteraciones, es la tendencia a presentar hemorragias localizadas, por lo que muchos veces son interpretadas como un problema local, manejándose como tal. Otro problema diagnóstico es debido a la subjetividad para evaluar la intensidad del sangramiento. A veces serán interpretados como normales a pesar de ser francamente abundantes o viceversa. Por lo antes planteado, destaca la importancia de entender cómo funciona la hemostasia primaria y como la alteración de la función plaquetaria afecta a los niños

Modificaçöes fisiológicas do aparelho cardiovascular / Physiological changes in cardiovascular system

As variaçöes circadianas säo conhecidas, há tempos, por influenciar os diversos sistemas fisiológicos, entre eles o cardiovascular. O estudo de mecanismos com variaçäo circadiana que alteram o funcionamento do sistema cardiovascular e suas doenças têm aumentado muito nos últimos anos devido à sua relevância clínica. Através desses trabalhos se pôde conhecer melhor a fisiopatologia, a epidemiologia e os fatores envolvidos nas doenças cardiovasculares. Dessa forma ficou evidente a maior incidência de eventos cardíacos pelas horas da manhä, assim como os possíveis mecanismos envolvidos nessa variaçäo durante as horas do dia. A pressäo arterial sanguínea, os níveis plasmáticos de catecolaminas e cortisol, a agregabilidade plaquetária e a açäo do sistema fibrinolítico säo os mecanismos que mais se destacam. Desse modo, tornou-se possível o desenvolvimento de novas estratégias terapêuticas, levando-se em consideraçäo o momento do dia de maior risco para o desenvolvimento das doenças cardiovasculares.

Co-activation of Gi and Gq proteins exerts synergistic effect on human platelet aggregation through activation of phospholipase C and Ca2+ signalling pathways

Our previous studies have shown that subthreshold concentrations of two platelet agonists exert synergistic effects on platelet aggregation. Here we studied the mechanism of synergistic interaction of 5-hydroxytryptamine (5-HT) and epinephrine mediated platelet aggregation. We show that 5-HT had no or little effect on aggregation but it did potentiate the aggregation response of epinephrine. The synergistic interaction of 5-HT (1-5 microM) and epinephrine (0.5-2 microM) was inhibited by alpha2-adrenoceptor blocker (yohimbine; IC50= 0.4 microM), calcium channel blockers (verapamil and diltiazem with IC50 of 10 and 48 mM, respectively), PLC inhibitor (U73122; IC50=6 microM) and nitric oxide (NO) donor, SNAP (IC50=1.6 microM)). The data suggest that synergistic effects of platelet agonists are receptor-mediated and occur through multiple signalling pathways including the activation PLC/Ca2+ signalling cascades.

Bloqueadores de las glicoproteínas IIb/IIIa: una nueva clase de antiagregantes plaquetarios de uso en cardiología / Glycoproteins IIB/IIIA blockers: a new class of platelets aggregates used in cardiology

La agregación plaquetaria es el mecanismo fisiopatológico más importante en la génesis de los síndromes coronarios agudos. Recientemente se ha incorporado una nueva clase de antiagregantes plaquetarios para el manejo de estos síndromes: los bloqueadores de las glicoproteínas IIb/IIIa (GP IIb/IIIa). En este trabajo se presenta una somera revisión de los mecanismos de agregación plaquetaria y de sus posibles vías de inhibición, con especial énfasis en el bloqueo de los receptores GP IIb/IIIa, vía final de la agregación plaquetaria. Se revisa la literatura concerniente al uso e indicaciones de los diferentes bloqueadores GP IIb/IIIa (intravenosos y orales) y los principales estudios randomizados de angioplastia transluminal percutánea coronaria (PTCA), angina inestable e infarto sin onda Q. En general, se observa una disminución de un 35 por ciento de la mortalidad y del infarto en relación a intervenciones coronarias y un porcentaje variable en la reducción de eventos coronarios a largo plazo. Estudios futuros deberán establecer la efectividad del uso de estas drogas en combinación con trombolíticos para el manejo del infarto del miocardio con onda Q

A comparative study of platelets behaviour in controls and acute myocardial infarction patients.

Acute myocardial infarction is one of the leading vascular diseases. Platelet-endothelium plays a crucial role in its etiopathogenesis. The present study was undertaken to compare the platelet aggregability in controls and acute myocardial infarction patients along with its effect on the peripheral platelet count. The work was conducted in five patients from ICCU and 5 controls between the age group of 40-60 years by using Chronolog Dual Channel Aggrometer with ADP and epinephrine as agonists. The platelets were counted by hemocytometry. The results were statistically analysed by Student's 't' test which was found to be significant. There was increase in the aggregation index in patients compared to controls. It was also observed that the degree of increase was more with ADP than epinephrine. Relatively, there was tendency of low platelet count. The increase in the aggregation index can be attributed to the hyperreactiveness of the platelets to ADP than epinephrine. The relative thrombocytopenia can be accounted to the sequestration of platelets in the coronary microvasculature. In conclusion, balance between EDRF and EDCF determines the platelet activation.