1/64. Determination of heparin-induced thrombocytopenia: a rapid flow cytometric assay for direct demonstration of antibody-mediated platelet activation.heparin-induced thrombocytopenia (HIT) and thrombosis are serious complications of heparin therapy. Recently, we have reported a practical and rapid functional flow cytometric assay (FCA) for the diagnosis of HIT with high specificity and sensitivity compared with the radioactive serotonin-release assay (SRA). In the present study, we added an immune-neutralization assay to directly demonstrate the antibody-mediated process, and tested the immune compatibility of low-molecular-weight heparin (LMWH) Lovenox and the heparinoid Orgaran (danaproid) using plasma from 18 patients with HIT confirmed by both FCA and SRA. The clinical utility of this modified method is demonstrated by a pediatric patient with a complex clinical presentation who developed thrombocytopenia with multiple thromboses while on heparin therapy. ELISA and SRA (performed in three independent laboratories) for diagnosis of HIT were both negative. In contrast, the FCA for detecting activated platelets expressing anionic phospholipids, was highly and reproducibly positive with both unfractionated and LMWH. Another FCA also demonstrated the surface expression of the alpha-granule membrane p-selectin (CD62p). Compatibility testing with the heparinoid Orgaran was also positive (and with plasma from 4 of the 18 patients with HIT). heparin was discontinued, along with full recovery of the platelet count. The capacity of the patient's plasma to activate platelets in the presence of heparin gradually decreased over 4 weeks consistent with antibody clearance. The responsible mechanism was clarified using an immune-neutralization assay, which showed a dose response neutralization of the plasma activity by antibodies against human immunoglobulin g (IgG) and IgM. This assay was also reproducible in the 18 patients with HIT. We conclude that the functional FCA with its modification is practical, sensitive, and specific for reliable diagnosis of HIT. It can simultaneously assess the compatibility of alternative therapies and directly confirm the antibody-mediated process. Further, it is particularly useful to clarify mechanisms of thrombocytopenia and thrombosis and to direct therapy in patients with a complex presentation and confounding laboratory results who often need prompt diagnosis and treatment.- - - - - - - - - - ranking = 1keywords = membrane (Clic here for more details about this article) |
2/64. A case of primary antiphospholipid antibody syndrome with acute renal failure showing thrombotic microangiopathy.An 18-year-old woman complained of fever and edema and was admitted to Showa University Hospital for treatment of thrombocytopenia and deteriorating renal function. Laboratory studies demonstrated the presence of lupus anticoagulant (LA), prolongation of prothrombin time, hemolytic anemia, a negative Coombs' test, the absence of antinuclear antibodies, and a normal fibrinogen level. Renal biopsy revealed mesangial hypercellularity, severe endocapillary cell damage, and double contour of the basement membrane walls. Immunofluorescence studies demonstrated focal, peripheral, and finely granular deposits for IgG, IgM, and IgA but were negative for fibrinogen. Electron microscopy showed glomerular capillary loops with subendothelial widening and subendothelial deposits, mesangiolysis, mesangial interposition, and marked luminal narrowing. biopsy findings were consistent with thrombotic microangiopathy. The patient was treated with hemodialysis, methylprednisolone pulse therapy, and dipyridamole. After treatment, LA disappeared, the prothrombin time became normal, and renal function improved. The renal lesions in this patient were caused by primary antiphospholipid antibody syndrome. This case strongly suggests an important causal relationship between LA and renal lesions in thrombotic microangiopathy. We present this case to promote understanding of the pathogenesis of primary antiphospholipid antibody syndrome. copyright copyright 1999 S. Karger AG, Basel- - - - - - - - - - ranking = 1keywords = membrane (Clic here for more details about this article) |
3/64. Inherited macrothrombocytopenia with distinctive platelet ultrastructural and functional features.We report a family with inherited macrothrombocytopenia and characteristic large membrane complexes in the platelets. Two affected subjects had platelet counts of 40 and 65 x 10(9)/L respectively as assessed by contrast phase microscopy. Ultrastructural studies revealed giant spheroid platelets with characteristic large membrane complexes and/or giant vacuoles containing platelet organelles. Immunohistochemical studies of actin and tubulin showed a disorganization of the microtubule and actin systems. These abnormalities were absent in leukocytes, indicating a platelet-specific cytoskeleton disorder. Platelet autoantibodies were repeatedly absent. Nevertheless, in the peripheral blood we observed several figures of platelet phagocytosis by macrophages and neutrophils. The in vitro aggregometric response of platelets to ADP, collagen, thrombin, ristocetin was present, but shape change was absent. The urinary excretion of thromboxane a2 metabolites of the affected subjects were approximately 2 standard deviations above control values, in spite of a reduced maximal biosynthetic capacity of thromboxane from giant platelets assessed in vitro during whole blood clotting. This inherited platelet disorder shows structural and functional features which allow to distinguish it from other syndromes associated with giant platelets. We also propose to include ultrastructural and cytoskeletal studies in the diagnosis as well as in the classification of inherited giant platelet disorders.- - - - - - - - - - ranking = 2keywords = membrane (Clic here for more details about this article) |
4/64. Severe and relapsing upper gastrointestinal bleeding in a patient with Glanzmann's thrombasthenia.Glanzmann's thrombasthenia (GT) is a rare familial thrombocytic disease inherited as an autosomal recessive disorder that can induce hemorrhages due to a defect of platelet aggregation, resulting from the absence or reduced concentration of the membrane glycoproteic receptor binding the fibrinogen (integrin alpha(IIb)beta3). The gastrointestinal tract is the site of bleeding in only about 10% of cases but the related mortality is high (12.8%). Among the deaths due to hemorrhage, digestive bleeding causes 57.1%. According to reported data, the source of bleeding may be from preexisting gastroduodenal chronic and acute lesions. We report a case of severe and relapsing upper digestive bleeding in a woman with GT and coexisting thrombocytopenia (from HCV-related liver cirrhosis) and H. pylori-positive duodenal ulcer.- - - - - - - - - - ranking = 1keywords = membrane (Clic here for more details about this article) |
5/64. Platelet endothelial cell adhesion molecule-1 (PECAM-1) is a target glycoprotein in drug-induced thrombocytopenia.Drug-induced immune thrombocytopenia (DITP) is a serious complication of drug treatment. Previous studies demonstrated that most drug-dependent antibodies (DDAbs) react with the platelet membrane glycoprotein (GP) complexes IIb/IIIa and Ib/IX/V. We analyzed the sera from 5 patients who presented with DITP after intake of carbimazole. Notably, thrombocytopenia induced by carbimazole was relatively mild in comparison to patients with DITP induced by quinidine. The sera reacted with platelets in an immunoassay on addition of the drug. In immunoprecipitation experiments with biotin-labeled platelets and endothelial cells, reactivity with the platelet endothelial cell adhesion molecule-1 (PECAM-1, CD31) could be demonstrated, whereas neither GPIIb/IIIa nor GPIb/IX was precipitated in the presence of the drug. These results could be confirmed by GP-specific immunoassay (MAIPA) using monoclonal antibodies (mabs) against PECAM-1. In addition, the binding of DDAbs could be abolished by preincubation with soluble recombinant PECAM-1. carbimazole-dependent antibodies showed similar reactivity with platelets carrying the Leu(125) and Val(125) PECAM-1 isoforms, indicating that this polymorphic structure, which is located in the first extracellular domain, is not responsible for the epitope formation. Binding studies with biotin-labeled mutants of PECAM-1 and analysis of sera with mabs against different epitopes on PECAM-1 in MAIPA assay suggested that carbimazole-dependent antibodies prominently bound to the second immunoglobulin homology domain of the molecule. Analysis of 20 sera from patients with quinidine-induced thrombocytopenia by MAIPA assay revealed evidence that DDAbs against PECAM-1 are involved in addition to anti-GPIb/IX and anti-GPIIb/IIIa. We conclude that PECAM-1 is an important target GP in DITP. (Blood. 2000;96:1409-1414)- - - - - - - - - - ranking = 1keywords = membrane (Clic here for more details about this article) |
6/64. cholesterol granulomas of the lungs associated with microangiopathic hemolytic anemia and thrombocytopenia in pulmonary hypertension.cholesterol granulomas unrelated to endogenous lipoid pneumonia, pulmonary alveolar proteinosis, or cholesterol pneumonia are a rare finding during pneumectomy or autopsy. They have been occasionally reported in association with pulmonary hypertension. We report a case where these lesions were associated with long-standing pulmonary hypertension and microangiopathic hemolytic anemia and thrombocytopenia. Plexiform lesions were present in the pulmonary vasculature secondary to pulmonary hypertension, causing hemolysis and thrombocytopenia. We suggest that destruction of red blood cells and platelets could provide membrane lipids that are taken up by phagocytic cells, which promotes the formation of these cholesterol deposits.- - - - - - - - - - ranking = 1keywords = membrane (Clic here for more details about this article) |
7/64. Macrothrombocytopenia with abnormal demarcation membranes in megakaryocytes and neutropenia with a complete lack of sialyl-Lewis-X antigen in leukocytes--a new syndrome?A new megathrombocytopenic syndrome with giant platelets in peripheral blood and severe thrombocytopenia was diagnosed in a 4-month-old boy. His clinical course included repeated hemorrhagic incidents leading to death at age 37 months. bone marrow ultrastructural analysis revealed numerous dystrophic megakaryocytes with giant membrane complexes. Although these features were similar to those described for megakaryocytes in mice lacking the gene for transcription factor p45-NF-E2, no abnormalities in the p45-NF-E2 gene could be documented. Platelet membrane analysis showed a reduction in glycoprotein (GP) Ib, but normal content of GPIIb and GPIIIa. Analysis of genes encoding for GPIb alpha and beta, GPV, and GPIX ruled out the possibility that the observed platelet abnormality is a variant of bernard-soulier syndrome. A moderate neutropenia was associated with a complete lack of expression of sialyl-Lewis-X on the surface of polymorphonuclear neutrophils. A common defect in posttranslational modification of glycoproteins could account for the diverse cellular abnormalities.- - - - - - - - - - ranking = 6keywords = membrane (Clic here for more details about this article) |
8/64. Labor analgesia in a patient with paroxysmal nocturnal hemoglobinuria with thrombocytopenia.BACKGROUND AND OBJECTIVES: Paroxysmal nocturnal hemoglobinuria (PNH) is a form of acquired hemolytic anemia in which a defect of glycophosphatidylinositol anchor proteins in the cell membrane of bone marrow stem cells leads to activation of the complement system and consequent destruction of defective cells. The characteristics of this disease are an increased frequency of thrombotic events, anemia, and thrombocytopenia. methods: We report a case of a pregnant patient with PNH with thrombocytopenia who delivered vaginally after receiving epidural labor analgesia. Prophylaxis of thromboembolism was performed with heparin 1 hour after the removal of the epidural catheter, and repeated at 12-hour intervals. Sensory changes or motor changes and pain were monitored every 10 minutes for 8 hours after delivery. RESULTS: During analgesia, the patient reported complete pain relief. Delivery and the immediate postpartum period were without any untoward events. CONCLUSIONS: Four major factors influenced the anesthetic conduct used for the present patient: (1) the risk of an acute hemolytic crisis, (2) the need to perform prophylaxis for thromboembolism, (3) the need to reduce labor stress, and (4) minimizing the risk of missing an epidural hematoma. We also present a survey of the literature about PNH and discuss the anesthetic conduct in this patient.- - - - - - - - - - ranking = 1keywords = membrane (Clic here for more details about this article) |
9/64. Lepirudin anticoagulation for heparin-induced thrombocytopenia.Lepirudin is indicated for anticoagulation in patients with heparin-induced thrombocytopenia (HIT). We describe 2 cases of HIT and thrombosis in children with heart disease, including one that required extracorporeal membrane oxygenation. Lepirudin, dosed in the recommended adult weight--based fashion, was an effective antithrombotic agent in pediatric patients with HIT.- - - - - - - - - - ranking = 1keywords = membrane (Clic here for more details about this article) |
10/64. Paroxysmal nocturnal hemoglobinuria in a 63-year-old patient.Intermittently occuring hemolytic anemia can be the expression of paroxysmal nocturnal hemoglobinuria (PNH). diagnosis is made via the detection of decreased resistance of the erythrocytes to acidified serum or osmotic hemolysis. Furthermore, diagnostic proof is provided by the cytometric detection of several erythrocyte populations caused by the altered expression of an anchor protein (PIG-A protein) of the cell membrane. This report is of a case where "black morning urine" has been in existence for more than 10 years and in which the additional occurrence of icterus led to the diagnosis. The patient's spleen had been removed in 1964 because of idiopathic thrombopenia, in retrospect, however, thrombopenia within the framework of PNH should be considered.- - - - - - - - - - ranking = 1keywords = membrane (Clic here for more details about this article) |
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