Glanzmann thrombastenia

Glanzmann's thrombastenia (GT) is the most frequent inherited condition. GT is a genetic autosomal recessive disease caused by the alteration of the genes ITGA2B and ITGB3, located on the chromosome 17. The incidence of GT is calculated in 1 on 1000000. The patients, during their life, show episodes of mucocutaneous bleeding, epistaxis, and gingival bleeding. Some subjects required continuous bleeding transfusion. The aim of this case report is to demonstrate that oral assumption of tranexamic acid is a gold standard to prevent excessive bleeding...

Inherited platelet disorders are rare bleeding syndromes due to either platelet function abnormalities or thrombocytopenia which may be associated with functional defects. The haemorrhagic symptoms observed in these patients are mostly muco-cutaneous and of highly variable severity. Although 30 to 50% of the platelet disorders are still of unknown origin, the precise diagnosis of these pathologies by specialized laboratories together with haemorrhagic scores enables an assessment of the risk of bleeding in each patient...

A 64-year-old female receiving clopidogrel and aspirin antiaggregation therapy after percutaneous coronary intervention for non-STEMI myocardial infarction developed nontraumatic bilateral subdural hematoma with dizziness, vertigo and headache. Craniotomy had to be postponed because of reduced ADP platelet aggregability. Four days after clopidogrel withdrawal and transfusion of 12 platelet concentrate units, ADP aggregation transiently normalized and bilateral trepanation with hematoma evacuation was performed...

The established hypothesis for the increase on erythrocyte aggregation associated with a higher incidence of cardiovascular pathologies is based on an increase on plasma adhesion proteins concentration, particularly fibrinogen. Fibrinogen-induced erythrocyte aggregation has been considered to be caused by its nonspecific binding to erythrocyte membranes. In contrast, platelets are known to have a fibrinogen integrin receptor expressed on the membrane surface (the membrane glycoprotein complex alpha(IIb)beta(3))...

Glanzmann thrombastenia (GT) is a rare condition of an inherited autosomal recessive gene characterized with bleeding tendency. The condition is rarely met in the OR. and therefore it is essential that anesthesiologist be cognizant of the risk involved and be prepared with all necessary precautionary measures. We present a GT case in a 27-year-old male with a mass in the anticubital region of right wrist that was successfully excised using the non-invasive intravenous regional analgesia (IVRA). The use of platelet transfusion and the recombinant factor VIIa, are stressed...

This review on platelet research focuses on defects of adhesion, cytoskeletal organisation, signal transduction and secretion. Platelet defects can be studied by different laboratory platelet functional assays and morphological studies. Easy bruising or a suspected platelet-based bleeding disorder is of course the most obvious reason to test the platelet function in a patient. However, nowadays platelet research also contributes to our understanding of human pathology in other disciplines such as neurology, nephrology, endocrinology and metabolic diseases...

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Low density lipoprotein (LDL) is known to sensitize platelets to agonists via integrin mediated outside-in signaling (Hackeng, C. M., Huigsloot, M., Pladet, M. W., Nieuwenhuis, H. K., Rijn, H. J. M. v., and Akkerman, J. W. N. (1999) Arterioscler. Thromb. Vasc. Biol., in press). As outside in signaling is associated with phosphorylation of p125(FAK), the effect of LDL on p125(FAK) phosphorylation in platelets was investigated. LDL induced p125(FAK) phosphorylation in a dose- and time- dependent manner. The phosphorylation was independent of ligand binding to integrin alphaIIbbeta3 and aggregation, such in contrast to alpha-thrombin-induced p125(FAK) phosphorylation, that critically depended on platelet aggregation...

The aim of our study was to explore the role of platelets and their specific integrin receptors in mediating the interaction of 4 human tumor cell lines (3 melanoma and 1 carcinoma) with the extracellular matrix (ECM) under static and arterial flow conditions. Under static conditions, all 4 cell lines adhered to the ECM. The adhesion capacity of all 4 cell lines was virtually abolished by application of flow during incubation with the ECM. Under static conditions, tumor cell adhesion was not affected by adding platelets to the cell suspension and was slightly reduced by pre-coating the ECM with platelets prior to the addition of tumor cells...

The stimulation of human platelets with physiological agonists results in the incorporation of several proteins into the cytoskeleton, fibrinogen binding, and platelet aggregation. We recently demonstrated that the Ras-related low molecular weight GTP-binding protein Rap2B associates with the cytoskeleton in activated platelets and that this interaction requires platelet aggregation. In the present study we demonstrate that agonist-induced actin polymerization is necessary for the translocation of Rap2B to the cytoskeleton, suggesting that Rap2B interacts with the newly formed actin filaments...

Extracellular Ca2+ ions are required for platelet aggregation and we show that they enter two platelet pools. One pool is rapidly filled and easily displaced by EGTA. The second is filled more slowly and is not displaced by EGTA. The EGTA-displaceable pool is believed to be surface-located and was found to contain at least one class of saturable binding sites as well as a class of non-saturable binding sites. The saturable sites were found to be highly selective for Ca2+ (dissociation constant, 3.5 X 10(-7) M) even in the presence of 1 mM Mg2+ ions, and they took up between 261,000 and 307,000 Ca2+ ions/platelet...