Overview of normal hemostasis and bleeding disorders

Abnormal bleeding or bruising is frequently encountered in the clinical practice of dermatology. For the correct diagnosis and hence appropriate management of a bleeding patient, it is essential that a clinician must have a sound knowledge of pathophysiology of normal hemostasis as well as physical and laboratory evaluation of such patients

Resistencia a la proteína C activada como causa de trombofilia / Resistance to activated protein C as a pathogenic factor of thrombophilia

En los últimos tres años han ocurrido avances notables en el esclarecimiento de las causas de la trombofilia. Hasta hace poco los estudios de laboratorio en pacientes con trombofilia familiar permitían esclarecer la causa sólo en el 5-10 por ciento de los casos, en los que se identifican deficiencia de proteína C de coagulación, de proteína S de coagulación, de antitrombina III, etc. La recien identificación de la resistencia de la proteína C activada (RPCa) ha cambiado este panorama: hasta el 50 por ciento de los pacientes con trombofilia familiar tienen el genotipo de la RPCa, mutación de nucleótido G por A en la posición 1691 del gen del factor V, lo que produce la mutación R-506-Q (tipo Leiden) de la molécula del factor V. Esta mutación codifica la síntesis de un factor V con actividad precoagulante normal pero "resistente" a la acción lítica de la proteína C activada; ocurre en proporciones variables entre 0 y 15 por ciento de la población general y en poblaciones nórdicas en el defecto genético relacionado con enfermedad más frecuente de todos. El fenotipo de l RPCa se estudia en el laboratorio por medio de una modificación de la medición del tiempo de tromboplastina parcial activada y puede presentarse en pacientes con el genotipo de la RPCa o ser secundario a enfermedades autoinmunes, hepatopatías, empleo de anovulatorios, embarazo, etc. El estudio de todo paciente con trombofilia debe incluir la investigación del fenotipo y en su caso, el genotipo de la RPCA. Este estudio, junto con las investigaciones de las actividades antigénica y procoagulante de las proteínas C, S y antitrombina III, permiten esclarecer la causa de la trombofilia familiar en 60-70 por ciento de los casos

Immunoglobulins in acquired platelet dysfunction with eosinophilia.

Acquired platelet dysfunction with eosinophilia (APDE) is acquired bleeding diathesis associated with platelet dysfunction causing prolonged bleeding time. Most of them had eosinophilia. Various reports of the isolated cases had normal level of immunoglobulins but few had increased IgE. This report is different from others in that among 41 cases of APDE, it was found that most of them had normal levels of IgG, IgA, IgE but there was increased IgM in 95.1% of the cases. Increased in IgE was noticed in 7/24 cases (29.2%) and only half (3/6 cases) corresponded with eosinophilia.

Effect of extracorporeal circulation on platelet count and function

36 patients undergoing elective open heart surgery for repair of rheumatic disease or acyanotic congenital heart disease were the subject of this study. Platelet count and "Platelet aggregation" were found to decrease after cardiopulmonary bypass [CPB] significantly, this drop correlated negatively with pump time. Bleeding time was prolonged after CPB significantly and the prolongation correlated with the drop of platelet count and with the decrease in platelet aggregation. Bleeding time was positively correlated with pump time

Albinism and Hermansky-Pudlak syndrome in Puerto Rico

Five types of oculocutaneous albinism and two types of ocular albinism were found among 349 Puerto Rican albinos. The most prevalent type of albinism was the Hermansky-Pudlak syndrome (HPS). HPS was observed in five of every six albinos in Puerto Rico. The prevalence of HPS was highest in the northwestern quarter of the island, affecting approximately one in 1,800 persons, and approximately one in 22 are carriers of the gene. HPS is an autosomal recessively inherited triad of a tyrosinase-positive type of albinism, a hemorrhagic diathesis due to storage pool deficient platelets and accumulation of ceroid in tissues. The pigmentary phenotype of HPS albinos resembled that of any other type of oculocutaneous or ocular albinism. The most reliable method of diagnosing HPS is by a deficiency of platelet dense bodies observed by electron microscopy. The accumulation of ceroid in the tissues is associated with fibrotic restrictive lung disease and granulomatous enteropathic disease. The enteropathic disorder resembles Crohn's disease and with few exceptions, had its onset after 13 years of age. The major causes of death were fibrotic restrictive pulmonary disease, hemorrhagic episodes and sequelae of granulomatous enteropathic disease. Menometrorrhagia was common in women with HPS. No immune deficiency was found in HPS patients. The majority of patients with HPS had visal acuities of 20/200 or worse and consequently were legally blind. Albinos of all types, including HPS, lacked binocular...