China
Africa
Explore chapters and articles related to this topic
Hereditary Causes for Plasma Clotting Bleeding
Published in Harold R. Schumacher, William A. Rock, Sanford A. Stass, Handbook of Hematologic Pathology, 2019
Diagnosis is made by finding a prolonged bleeding time with a normal platelet count, normal PT, and prolonged PTT due to decreased factor VIII:C levels, usually ranging from 15% to 50%. Factor VIII:C levels are labile in these patients, and assays on specimens taken at different times may need to be performed to detect the nadir of factor VIII functional activity, von Willebrand antigen levels, if measured, are similar to the factor VIII:C level. The diagnosis is confirmed by measuring the von Willebrand factor activity, such as with a Ristocetin-induced platelet aggregation test. Ristocetin, an antibiotic, potentiates the attachment of the vWF to a platelet membrane receptor, glycoprotein Ib/IX. This platelet aggregation test is commercially available. The vWF levels are usually at 15–50%.
Platelet Disorders Douglas Triplett
Published in Genesio Murano, Rodger L. Bick, Basic Concepts of Hemostasis and Thrombosis, 2019
In 1971, Howard and Firkin introduced ristocetin as another tool in the diagnosis of von Willebrand’s syndrome.18 Ristocetin is an antibiotic that was found to aggregate platelets and cause severe thrombocytopenia in vivo.19 Ristocetin was found to induce platelet aggregation in normal patients, but not in patients with von Willebrand’s syndrome. Further study established a defective or reduced plasma component in these patients, which was a necessary cofactor for ristocetin-induced aggregation. The platelets of von Willebrand’s syndrome were entirely normal when this plasma component was added to platelet-rich plasma.20 Subsequently, an assay measuring this plasma factor was reported.21
Clinical Evidence and Consequences of the Association Between Hemostatic Functions and Malignancies
Published in László Muszbek, Hemostasis and Cancer, 2019
The aggristin (ristomycin) precipitation test is a new tool for the detection of fibrin monomer and fibrin degradation products in plasma, therefore it is useful in the laboratory diagnosis of DIC and in its differentiation from the primary fibrinogenolysis.58,59 The test was based on the observation of Watanabe and Tullis60 that ristocetin in appropriate concentration precipitates fibrin monomers and fibrin degradation products without precipitating fibrinogen and fibrinogen degradation products. They proposed the ristocetin precipitation test.61 Formerly, we studied ristomycin, another member of the vancomycin group of antibiotics, and demonstrated that it is fully capable of replacing ristocetin in the platelet aggregation process and also in the diagnostics of von Willebrand’s disease.62 It seems to be proved that ristomycin has the same properties as ristocetin, also in the precipitation of plasma proteins, and it is able to replace ristocetin in the laboratory diagnosis of intravascular clotting.59 This test proved to be positive in almost all the patients investigated, even when no or only moderate signs of DIC developed. A good correlation with the Thrombo-Wellco test and the poor sensitivity of the ethanol gelation test (EGT) are obvious from Table 8.
Effect of differently coated silver nanoparticles on hemostasis
Published in Platelets, 2021
Marija Milić, Barbara Vuković, Rinea Barbir, Barbara Pem, Mirta Milić, Vatroslav Šerić, Eleonore Frőhlich, Ivana Vinković Vrček
When no agonists where used, only PLL-AgNPs was able to cause platelet aggregation, similar to the action of PLL alone (Figure S2 in the SI). Indeed, cationic polypeptides have been found to enhance platelet aggregation by neutralizing net negative charge on platelet membrane [32]. These results are consistent with study reported by Jun et al. [15], although Huang et al. [13] reported no AgNPs effect on platelet aggregation. There are two possibilities to explain the findings. In the experiment without agonists, platelet aggregation was measured immediately after addition of AgNPs to whole blood samples, while the measurement of platelet aggregation in experiments with agonists started 30 min after the incubation of whole blood with AgNPs. Thus, if AgNPs induced platelet aggregation alone, there would be less platelets available for activation by agonists, which could result in decreased platelet aggregation. It has been shown that function, for instance of macrophages, is impaired upon exposure to NPs [33] and it is likely that a similar effect may also occur for platelets. The fact that only ristocetin produced this effect may be due to the stronger activating action of this molecule.
Harmonizing light transmission aggregometry in the Netherlands by implementation of the SSC-ISTH guideline
Published in Platelets, 2021
I.C.A. Munnix, R. Van Oerle, P. Verhezen, P. Kuijper, C.M. Hackeng, H.I.J. Hopman-Kerkhoff, F. Hudig, D. Van De Kerkhof, A. Leyte, M.P.M. De Maat, R.F.M. Oude Elferink, J. Ruinemans-Koerts, M. Schoorl, J. Slomp, H. Soons, A. Stroobants, E. Van Wijk, Y.M.C. Henskens
More or less the same effect is observed with collagen. Before standardization in 2013, low collagen concentrations (0.2–2 μg/mL) show more variation in maximum aggregation results of healthy volunteers in comparison to high collagen concentrations (4–10 μg/mL) on both Chronolog and APACT instruments (Figure 1d, e). After standardization in 2016, low collagen concentrations (1–2 μg/mL) show less variability in maximum aggregation on all instruments, compared to the LTA results of 2013 (Figure 1d). A fixed, high collagen concentration of 5 μg/mL displays roughly the same variation before and after standardization (Figure 1e). As expected, low concentrations of ristocetin result in very low maximal aggregation responses with a few outliers (Figure 1F). The standardization procedure does not affect these results. Higher ristocetin concentrations show CV ranges of 3% to 19% before and 3–22% after standardization (Figure 1g). For epinephrine 5 µM the CV before standardization is lower (Figure 1h). Finally, LTA results of arachidonic acid are relatively stable between different instruments before and after standardization (Figure 1i).
Recurrent melena in a diagnosed case of Bernard Soulier syndrome
Published in Journal of Community Hospital Internal Medicine Perspectives, 2021
Omair Ali Khan, Sheharyar Raashid, Sohaib Asghar, Ramsha Majeed, Mahnoor Fatima Sherazi, Fakeha Nayyer, Aisha Anis, Zainab Ehsan
Bernard Soulier Syndrome or BSS is a rare hematological disorder related to abnormal structure and function of platelets. It was initially described in 1948 by J Bernard and JP Soulier [1]. Other names for the disease include giant platelet syndrome, hemorrhagiparous thrombocytic dystrophy, macrothrombocytopenia, platelet glycoprotein Ib deficiency or Von Willebrand factor receptor deficiency. BSS has an autosomal recessive inheritance pattern affecting 1 in 1,000,000 people [2]. Characteristic lab findings include megakaryocytes, thrombocytopenia, increased bleeding time and impaired platelet agglutination in response to Ristocetin. It has also been classified as a giant platelet disorder, due to the appearance of abnormally large platelets. In addition to the typical clinical manifestations of epistaxis, cutaneous and mucosal bleeding, the disorder can also rarely present with menorrhagia and gastrointestinal tract bleeding. The dysfunction results from mutations which include nonsense, deletion, or missense mutations of the surface glycoprotein complex encoding genes [3]. Once diagnosed, the medical opinion of a hematologist should be sought as the management plan of each patient must be tailored according to the severity and symptoms of each individual case. There is no cure or prophylactic measures that can be implemented for bleeding disorders, it is only possible to manage the risks and complications.