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Haemostasis and Thrombosis
Published in Karl H. Pang, Nadir I. Osman, James W.F. Catto, Christopher R. Chapple, Basic Urological Sciences, 2021
AdhesionVWF binds to exposed collagen. Some VWF — released from the EC — is already bound to the extravascular collagen.Platelets bind to the VWF under high shear via glycoprotein Ib (GPIb).At low shear and after capture by the VWF, platelets bind to collagen via GPIaIIa and GPVI.
Antiplatelet Therapy
Published in Hau C. Kwaan, Meyer M. Samama, Clinical Thrombosis, 2019
T. Lecompte, M. M. Samama, Hau C. Kwaan
Platelet adhesion involves thrombogenic components of the subendothelium such as collagen and, in some cases, the von Willebrand factor which interacts with the glycoprotein Ib of the platelet membrane. Aspirin is not able to inhibit adhesion itself nor the subsequent secretion. Prostacyclin only minimally inhibits adhesion but satisfactorily blocks the activation it entails. Only monoclonal antibodies directed towards the von Willebrand factor or its platelet receptors can truly impede this function, as can small peptides such as Arg-Gly-Asp-Ser.1
Case 67
Published in Atul B. Mehta, Keith Gomez, Clinical Haematology, 2017
This patient suffers from the May–Hegglin anomaly, a rare, dominantly inherited disorder which runs a benign course. Bleeding manifestations are rare and platelet function studies are essentially normal. Bernard–Soulier syndrome is an autosomal recessive or codominant trait also associated with giant platelets and thrombocytopenia; but there are no neutrophil inclusions, bleeding manifestations are common and platelet membranes lack glycoprotein Ib and fail to aggregate in response to ristocetin.
Keeping a balance in chronic lymphocytic leukemia (CLL) patients taking ibrutinib: ibrutinib-associated adverse events and their management based on drug interactions
Published in Expert Review of Hematology, 2021
Hee Jeong Cho, Dong Won Baek, Juhyung Kim, Jung Min Lee, Joon Ho Moon, Sang Kyun Sohn
The vulnerability to bleeding among ibrutinib users has not been clearly elucidated. Platelet dysfunction after ibrutinib was suggested as a mechanism behind the bleeding tendency because most phenotypes of bleeding presented with features such as bruising or petechiae, and bleeding occurred despite normal platelet counts [40]. It has been found that the Tec family kinase pathways including BTK play an important role in platelet aggregation during the hemostasis process via collagen receptor glycoprotein IV (GPIV) [41,42]. Additionally, BTK has also been found to be essential for thrombosis formation via the von Willebrand factor (vWF) and a glycoprotein Ib (GPIb)-mediated pathway in vivo [43]. These findings suggest that in addition to the on-target inhibition of the BCR signaling pathway in malignant B cells, ibrutinib may also exhibit off-target inhibition of the hemostasis pathway via Tec kinase and BTK; this results in increased bleeding events while taking ibrutinib. A study using blood samples obtained from 14 patients with CLL and MCL supported this idea; collagen-associated platelet aggregation and its adhesion to vWF were inhibited by the administration of ibrutinib, and were correlated with the occurrence of bleeding [44].
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 is a congenital bleeding disorder caused by platelet dysfunction. Its inheritance is typically of an autosomal recessive pattern although rare cases following an autosomal dominant pattern due to mutations in the GP1BA or GP1BB gene have also been seen [1]. It is characterized by an impairment of platelet adhesive function via a defect in the glycoprotein Ib/IX complex that binds endothelial VWF. It has a reported prevalence of one in one million individuals, and about 200 cases have been reported [2]. The condition was first described in 1948 by two French hematologists, Jean Bernard and Jean Pierre Soulier who had described a male patient with a bleeding defect characterized by increased bleeding time, thrombocytopenia and appearance of megakaryocytes. Hemorrhagiparous thrombocytic dystrophy (Dystrophie thrombocytaire-hémorragipare congénitale) was the name given to the disorder by them [3]. In this syndrome, thrombocytopenia is observed with abnormally large and functionally impaired platelets. The clinical manifestations are diverse and include purpura, epistaxis, menorrhagia, gingival and gastrointestinal bleeding, hematuria or hematoma [4].
Myelin-associated proteins are potential diagnostic markers in patients with primary brain tumour
Published in Annals of Medicine, 2021
Olga M. Koper-Lenkiewicz, Anna J. Milewska, Joanna Kamińska, Karol Sawicki, Robert Chrzanowski, Justyna Zińczuk, Joanna Reszeć, Marzena Tylicka, Ewa Matuszczak, Joanna Matowicka-Karna, Zenon Mariak, Mariusz W. Mucha, Robert Pawlak, Violetta Dymicka-Piekarska
An unexpected result was the finding of some serum OMgp concentrations in both primary brain tumours (N = 11) and non-tumoural individuals (N = 7). This is interesting because according to the literature OMgp is exclusively expressed only within the central nervous system [6]. The primary structure of OMgp is composed of four domains. At the N-terminus there is 32 aa Cys-rich motif (CR), which is followed by a 7 ½ tandem Leucine-rich repeats (LRRs) of 24 aa each, and subsequently by a domain of 4 ½ repeats of 40 residues each rich in Ser/Thr. The COOH-terminus contains glycosylphosphatidylinositol (GPI) as a membrane anchor. Among proteins, the platelet glycoprotein Ib (GPIb) was found to be the most similar to OMgp. These two proteins share richly in CR and LRRs motifs, but also contain Ser/Thr-rich regions [22]. Moreover, Mikol et al. [22] showed the similarity between the GPIbαβ heterodimer gene and the OMgp gene, which indicates that these two proteins may also be related by gene structure. The possible cross-reactivity in the ELISA test between these two proteins could account for our current results. For this reason, the obtained results regarding OMgp concentrations will not be subjected to further discussion.