GPIBA

Aspirin resistance (AR) is a pressing problem in current ischemic stroke care. Although the role of genetic variations is widely considered, the data still remain controversial. Our aim was to investigate the contribution of genetic features to laboratory AR measured through platelet aggregation with arachidonic acid (AA) and adenosine diphosphate (ADP) in ischemic stroke patients. A total of 461 patients were enrolled. Platelet aggregation was measured via light transmission aggregometry. Eighteen single-nucleotide polymorphisms (SNPs) in ITGB3 , GPIBA , TBXA2R , ITGA2 , PLA2G7 , HMOX1 , PTGS1 , PTGS2 , ADRA2A , ABCB1 and PEAR1 genes and the intergenic 9p21...

CONTEXT: Although several risk proteins for hypothyroidism have been reported in recent years, many more plasma proteins have not been tested. OBJECTIVE: To determine potential mechanisms and novel causal plasma proteins for hypothyroidism using Mendelian randomization (MR). METHODS: A large-scale plasma proteome MR analysis was conducted using protein quantitative trait loci (pQTLs) for 2297 plasma proteins. We classified pQTLs into four different groups...

OBJECTIVE: To ascertain the role of platelet glycoprotein Ib alpha chain (GPIbα) plasma protein levels in cardiovascular, autoimmune and autoinflammatory diseases and whether its effects are mediated by platelet count. METHODS: We performed a two-sample Mendelian randomization (MR) study, using both cis and trans-acting protein expression quantitative trait loci (pQTL) near GP1BA and BRAP genes as instruments. To assess if platelet count mediated the effect, we then performed a two-step MR study...

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Blood-brain barrier (BBB) disruption, thrombus formation and immune-mediated inflammation are important steps in the pathophysiology of cerebral ischemia-reperfusion injury but are still inaccessible to therapeutic interventions. Recent studies have provided increasing evidence that blocking of platelet glycoprotein (GP) receptor Ib might represent a novel target in treating acute ischemic stroke. This research was conducted to explore the therapeutic efficacy and potential mechanisms of GPIbα inhibitor (anfibatide) in a model of brain ischemia-reperfusion injury in mice...

Interaction between von Willebrand factor (VWF) and platelet GPIbα is required for primary haemostasis. Lack or loss-of-function in the ligand-receptor pair results in bleeding complications. Paradoxically, gain-of-function mutations in VWF or GPIbα also result in bleeding complications as observed in type 2B von Willebrand disease (VWD) and platelet-type- (PT-) VWD, respectively. A similar phenotype is observed with increased ristocetin-induced platelet agglutination and disappearance of the highest molecular weight multimers of VWF...

OBJECTIVE: To investigate the influence of divalent cation chelator EDTA and heparin sodium on the detection of ITP platelet-specific autoantibodies by the modified monoclonal antibody immobilization of platelet antigen assay (MAIPA) and to explore the relationship between types of platelet specific autoantibodies and glucocorticoid efficacy. METHODS: The samples were obtained from EDTA- and heparin- anticoagulant ITP patients, respectively, so as to detect the platelet-specific autoantibodies (GPIIb/IIIa and GPIbα) in 140 ITP samples by modified MAIPA, then the differences between these two methods were compared...

In recent years, candidate genes and proteins implicated in platelet function have been identified by various genomic approaches. To elucidate their exact role, we aimed to develop a method to apply miRNA interference in platelet progenitor cells by using GPIbα as a proof-of-concept target protein. After in silico and in vitro screening of siRNAs targeting GPIbα (siGPIBAs), we developed artificial miRNAs (miGPIBAs), which were tested in CHO cells stably expressing GPIb-IX complex and megakaryoblastic DAMI cells...

BACKGROUND: Single nucleotide polymorphisms (SNPs) in platelet-associated genes partly explain inherent variability in platelet counts. Patients with monoallelic Bernard Soulier syndrome due to the Bolzano mutation (GPIBA A156V) have variable platelet counts despite a common mutation for unknown reasons. OBJECTIVES: We investigated the effect of the most common SNP (R307H) in the hematopoietic-specific tubulin isotype β-1 in these Bernard Soulier patients and potential microtubule-based mechanisms of worsened thrombocytopenia...

BACKGROUND: Von Willebrand Factor (VWF) A1-domain binding to platelet receptor GpIbα is an important fluid-shear dependent interaction that regulates both soluble VWF binding to platelets, and platelet tethering onto immobilized VWF. We evaluated the roles of different structural elements at the N-terminus of the A1-domain in regulating shear dependent platelet binding. Specifically, the focus was on the VWF D'D3-domain, A1-domain N-terminal flanking peptide (NFP), and O-glycans on this peptide...

METHODS: The studied group comprises 124 patients with acute myocardial infarction on dual antiplatelet therapy with acetylsalicylic acid (ASA) and thienopyridines. Antiplatelet therapy was monitored by platelet-rich plasma light transmittance aggregometry (LTA) using the APACT 4004 analyzer (Helena Laboratories) and by whole blood impedance aggregometry (multiple electrode aggregometry [MEA]) using the Multiplate analyzer (Dynabyte). Platelet aggregation was detected after stimulation with arachidonic acid for detection of aspirin resistance and with adenosine diphosphate (ADP) and prostaglandin E1 for detection of thienopyridine resistance...

BACKGROUND: The effects of blood platelet inhibitors are often not quite equivalent under in vivo and in vitro conditions. Amongst various models of human pathology using laboratory animals, mice offer several benefits that make them convenient tools for studying the putative therapeutic value of various compounds. However, despite its advantages, the mouse model has methodological limitations concerning the small amount of blood available and technical difficulties with its collection...

Bernard-Soulier syndrome (BSS) is a severe inherited bleeding disorder due to defects in GPIb/IX/V, a platelet receptor that normally functions as a platelet membrane receptor for von Willebrand factor, thrombin and factor XI. BSS results from mutations in GP1BA, GP1BB or GP9 genes. In 15 patients with Bernard-Soulier syndrome from Western India, we amplified the entire coding sequences of GP1BA, GP1BB and GP9 genes and directly sequenced them. Twelve homozygous changes have been identified, out of which ten were novel mutations...

OBJECTIVE: Aspirin is an antiplatelet agent commonly used in treatment of patients with high risk to develop stroke and myocardial infarction. However, inter-individual variability regarding the inhibition of platelet function by aspirin is well documented. In this study, the correlation between platelet glycoproteins (GPIa C807T and GPIba C-5T) and cyclooxygenase 2 (COX-2G-765C) polymorphisms and antiplatelet response in patients treated with aspirin was investigated. METHODS: Jordanian adult patients (n=584) who are taking aspirin as an antiplatelet agent participated in the study...

Allele and genotype frequencies of 10 single nucleotide polymorphisms in F12, PON1, PON2, NOS2, PDE4D, HIF1a,GPIba, CYP11B2 genes were studied in a group of Russian patients with ischemic stroke (IS) from central regions of the Russian Federation and healthy donors matched for sex, age and ethnicity. The genotyping procedure included the amplification of selected DNA sequences with the following hybridization of fluorescently-labeled regions with allele-specific DNA-probes immobilized on a biochip. An analysis of allele and genotype frequencies for each gene in IS patients and controls did not reveal any significant differences...

BACKGROUND: Bernard-Soulier syndrome is a very rare form of inherited thrombocytopenia that derives from mutations in GPIbα, GPIbβ, or GPIX and is typically inherited as a recessive disease. However, some years ago it was shown that the monoallelic c.515C>T transition in the GPIBA gene (Bolzano mutation) was responsible for macrothrombocytopenia in a few Italian patients. DESIGN AND METHODS: Over the past 10 years, we have searched for the Bolzano mutation in all subjects referred to our institutions because of an autosomal, dominant form of thrombocytopenia of unknown origin...

BACKGROUND: Bernard-Soulier syndrome (BSS) is an extremely rare (1:1 million) bleeding disorder of platelet adhesion, caused by defects in the glycoprotein (GP)Ib/IX/V complex. PATIENTS AND METHODS: The diagnosis in 27 patients was based on low platelet count, presence of giant platelets and aggregometry studies. Flow cytometry to assess the surface GPIb/IX/V complex showed reduced (7.7-57%) expression. gDNA was screened for mutations in the GPIBA, GPIBB, GP9 genes using PCR-conformation sensitive gel electrophoresis (CSGE)...

BACKGROUND: Although many genetic epidemiology and biomarker studies have been conducted to examine associations of genetic variants and circulating proteins with cardiovascular disease and risk factors, there has been little study of gene expression or transcriptomics. Quantitative differences in the abundance of transcripts has been demonstrated in malignancies, but gene expression from a large community-based cohort examining risk of cardiovascular disease has never been reported. METHODS AND RESULTS: On the basis of preliminary microarray data and previously suggested genes from the literature, we measured expression of 48 genes by high-throughput quantitative reverse-transcriptase polymerase chain reaction in 1846 participants of the Framingham Offspring cohort from RNA derived from isolated platelets and leukocytes...

This study used recombinant A1A2A3 tri-domain proteins to demonstrate that A domain association in von Willebrand factor (VWF) regulates the binding to platelet glycoprotein Ibalpha (GPIbalpha). We performed comparative studies between wild type (WT) A1 domain and the R1450E variant that dissociates the tri-domain complex by destabilizing the A1 domain. Using urea denaturation and differential scanning calorimetry, we demonstrated the destabilization of the A1 domain structure concomitantly results in a reduced interaction among the three A domains...

Polymorphisms affecting platelet receptors and intracellular proteins have been extensively studied in relation to their potential influence in thrombosis and haemorrhages. However, few reports have addressed their impact on platelet function, with contradictory results. Limitations of these studies include, among others, small number of patients, the platelet functional parameters analyzed and their known variability in the healthy population. We studied the effect of six polymorphisms [ITGB3 1565T > C (HPA-1), GPIBA variable number tandem repeat and 524C > T (HPA-2), ITGA2 807C > T, ADRA2A 1780A > G, and TUBB1 Q43P] on platelet function in 286 healthy subjects and their potential pathogenetic role in 160 patients with hereditary mucocutaneous bleeding of unknown cause...