scholarly journals Thromboelastometry and Platelet Function during Acclimatization to High Altitude

2018 ◽  
Vol 118 (01) ◽  
pp. 063-071 ◽  
Author(s):  
Alistair Rocke ◽  
Gordon Paterson ◽  
Matthew Barber ◽  
Alexander Jackson ◽  
Shona Main ◽  
...  
Keyword(s):  
High Altitude ◽  
Sea Level ◽  
Platelet Function ◽  
Platelet Reactivity ◽  
Adenosine Diphosphate ◽  
Coagulation Factors ◽  
Significant Rise ◽  
Fibrinogen Concentration ◽  
Increased Risk ◽  
Using Data

AbstractInteraction between hypoxia and coagulation is important given the increased risk of thrombotic diseases in chronically hypoxic patients who reside at sea level and in residents at high altitude. Hypoxia alters the proteome of platelets favouring a prothrombotic phenotype, but studies of activation and consumption of specific coagulation factors in hypoxic humans have yielded conflicting results. We tested blood from 63 healthy lowland volunteers acclimatizing to high altitude (5,200 m) using thromboelastometry and assays of platelet function to examine the effects of hypoxia on haemostasis. Using data from two separate cohorts of patients following identical ascent profiles, we detected a significant delay in clot formation, but increased clot strength by day 7 at 5,200 m. The latter finding may be accounted for by the significant rise in platelet count and fibrinogen concentration that occurred during acclimatization. Platelet function assays revealed evidence of platelet hyper-reactivity, with shortened PFA-100 closure times and increased platelet aggregation in response to adenosine diphosphate. Post-expedition results were consistent with the normalization of coagulation following descent to sea level. These robust findings indicate that hypoxia increases platelet reactivity and, with the exception of the paradoxical delay in thromboelastometry clotting time, suggest a prothrombotic phenotype at altitude. Further work to elucidate the mechanism of platelet activation in hypoxia will be important and could impact upon the management of patients with acute or chronic hypoxic respiratory diseases who are at risk of thrombotic events.

scholarly journals Hypoxia Modulates Platelet Purinergic Signalling Pathways

2019 ◽  
Vol 120 (02) ◽  
pp. 253-261 ◽  
Author(s):  
Gordon G. Paterson ◽  
Jason M. Young ◽  
Joseph A. Willson ◽  
Christopher J. Graham ◽  
Rebecca C. Dru ◽  
...  
Keyword(s):  
High Altitude ◽  
Sea Level ◽  
Platelet Reactivity ◽  
Clinical Importance ◽  
Adenosine Diphosphate ◽  
Purinergic Signalling ◽  
Systematic Assessment ◽  
Vasp Phosphorylation ◽  
The Impact ◽  
Induced Aggregation

Abstract Background Hypoxia resulting from ascent to high-altitude or pathological states at sea level is known to increase platelet reactivity. Previous work from our group has suggested that this may be adenosine diphosphate (ADP)-specific. Given the clinical importance of drugs targeting ADP pathways, research into the impact of hypoxia on platelet ADP pathways is highly important. Methods Optimul aggregometry was performed on plasma from 29 lowland residents ascending to 4,700 m, allowing systematic assessment of platelet reactivity in response to several platelet agonists. Aggregometry was also performed in response to ADP in the presence of inhibitors of the two main ADP receptors, P2Y1 and P2Y12 (MRS2500 and cangrelor, respectively). Phosphorylation of vasodilator-stimulated phosphoprotein (VASP), a key determinant of platelet aggregation, was analysed using the VASPFix assay. Results Hypobaric hypoxia significantly reduced the ability of a fixed concentration of cangrelor to inhibit ADP-induced aggregation and increased basal VASP phosphorylation. However, in the absence of P2Y receptor inhibitors, we did not find evidence of increased platelet sensitivity to any of the agonists tested and found reduced sensitivity to thrombin receptor-activating peptide-6 amide. Conclusion Our results provide evidence of increased P2Y1 receptor activity at high altitude and suggest down-regulation of the P2Y12 pathway through increased VASP phosphorylation. These changes in ADP pathway activity are of potential therapeutic significance to high-altitude sojourners and hypoxic sea level patients prescribed platelet inhibitors and warrant further investigation.

scholarly journals MicroRNA as Biomarkers for Platelet Function and Maturity in Patients with Cardiovascular Disease

2021 ◽  
Author(s):  
Oliver Buchhave Pedersen ◽  
Erik Lerkevang Grove ◽  
Steen Dalby Kristensen ◽  
Peter H. Nissen ◽  
Anne-Mette Hvas
Keyword(s):  
Cardiovascular Disease ◽  
Platelet Function ◽  
Assessment Tool ◽  
Platelet Reactivity ◽  
Thrombus Formation ◽  
Quality Assessment Tool ◽  
Treatment And Prevention ◽  
Increased Risk ◽  
Meta Analyses ◽  
Potential Use

AbstractPatients with cardiovascular disease (CVD) are at increased risk of suffering myocardial infarction. Platelets are key players in thrombus formation and, therefore, antiplatelet therapy is crucial in the treatment and prevention of CVD. MicroRNAs (miRs) may hold the potential as biomarkers for platelet function and maturity. This systematic review was conducted using the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). To identify studies investigating the association between miRs and platelet function and maturity in patients with CVD, PubMed and Embase were searched on October 13 and December 13, 2020 without time boundaries. Risk of bias was evaluated using a standardized quality assessment tool. Of the 16 included studies, 6 studies were rated “good” and 10 studies were rated “fair.” In total, 45 miRs correlated significantly with platelet function or maturity (rho ranging from –0.68 to 0.38, all p < 0.05) or differed significantly between patients with high platelet reactivity and patients with low platelet reactivity (p-values ranging from 0.0001 to 0.05). Only four miRs were investigated in more than two studies, namely miR-223, miR-126, miR-21 and miR-150. Only one study reported on the association between miRs and platelet maturity. In conclusion, a total of 45 miRs were associated with platelet function or maturity in patients with CVD, with miR-223 and miR-126 being the most frequently investigated. However, the majority of the miRs were only investigated in one study. More data are needed on the potential use of miRs as biomarkers for platelet function and maturity in CVD patients.

The impact of renal function on platelet reactivity and clinical outcome in patients undergoing percutaneous coronary intervention with stenting

2014 ◽  
Vol 112 (12) ◽  
pp. 1174-1181 ◽  
Author(s):  
Nicoline Breet ◽  
Corine de Jong ◽  
Willem Jan Bos ◽  
Jochem van Werkum ◽  
Heleen Bouman ◽  
...  
Keyword(s):  
Renal Function ◽  
Antiplatelet Therapy ◽  
Platelet Function ◽  
Platelet Reactivity ◽  
Light Transmittance ◽  
Clinical Trial Registration ◽  
Platelet Function Test ◽  
Increased Risk ◽  
Function Test ◽  
The Impact

SummaryPatients with chronic kidney disease (CKD) have an increased risk of cardiovascular disease. Previous studies have suggested that patients with CKD have less therapeutic benefit of antiplatelet therapy. However, the relation between renal function and platelet reactivity is still under debate. On-treatment platelet reactivity was determined in parallel by ADP- and AA-induced light transmittance aggregometry (LTA) and the VerifyNow® System (P2Y12 and Aspirin) in 988 patients on dual antiplatelet therapy, undergoing elective coronary stenting. Patients were divided into two groups according to the presence or absence of moderate/severe CKD (GFR<60 ml/min/1.73 m2). Furthermore, the incidence of all-cause death, non-fatal acute myocardial infarction, stent thrombosis and stroke at one-year was evaluated. Patients with CKD (n=180) had significantly higher platelet reactivity, regardless of the platelet function test used. Patients with CKD more frequently had high on-clopidogrel platelet reactivity (HCPR) and high on-aspirin platelet reactivity (HAPR) regardless of the platelet function test used. After adjustment for potential confounders, this was no longer significant. The event-rate was the highest in patients with both high on-treatment platelet reactivity (HPR) and CKD compared to those with neither high on-treatment platelet reactivity nor CKD. In conclusion, the magnitude of platelet reactivity as well as the incidence of HPR was higher in patients with CKD. However, since the incidence of HPR was similar after adjustment, a higher rate of co-morbidities in patients with CKD might be the major cause for this observation rather than CKD itself. CKD-patients with HCPR were at the highest risk of long-term cardiovascular events.Clinical Trial Registration: www.clinicaltrials.gov: NCT00352014.

Sticky Platelet Syndrome: 35 Years of Growing Evidence

2019 ◽  
Vol 45 (01) ◽  
pp. 061-068 ◽  
Author(s):  
Pavol Holly ◽  
Jan Stasko ◽  
Peter Kubisz
Keyword(s):  
Past Research ◽  
Adenosine Diphosphate ◽  
Coagulation Factors ◽  
Laboratory Findings ◽  
Antithrombin Deficiency ◽  
Ongoing Research ◽  
Increased Risk ◽  
Platelet Disorder ◽  
Present Understanding

AbstractSince the identification of antithrombin deficiency by Egeberg in 1956, ongoing research in prothrombotic defects continues to progress. Interestingly, past research has predominantly focused on coagulation factors and not on other components of the hemostatic system. The possible role of platelet function defects in the development of thrombotic events was suggested for the first time in the late 1970s, when an increased platelet adhesiveness and aggregation after epinephrine (EPI) and adenosine diphosphate (ADP) was found in a group of patients with unexplained transient ischemic attack. Clinical evidence for other types of thrombotic events (e. g. myocardial infarction, ischemic stroke, optic neuropathy, and pregnancy-related complications) with similar laboratory findings was provided by several authors in the 1980s and 1990s, with Drs. Mammen and Bick undertaking key research. The familial occurrence was noted as well, and the term sticky platelet syndrome was introduced by Holliday in 1983 to describe the defect. The term in our present understanding describes a thrombophilic qualitative platelet disorder characterized by increased in vitro platelet aggregation after the addition of very low concentrations of ADP and/or EPI and an increased risk of thromboembolic (predominantly arterial) events. Although now recognized for 35 years, significant issues, namely its etiology, inheritance, epidemiology, and diagnostics, remain a matter of vigorous debate. The aim of this review is to summarize the history, key works, and present understanding of the syndrome and to outline present-day diagnostic and clinical problems and controversies.

scholarly journals In vivo effects of eltrombopag on platelet function in immune thrombocytopenia: no evidence of platelet activation

Blood ◽  
2012 ◽  
Vol 119 (17) ◽  
pp. 4066-4072 ◽  
Author(s):  
Bethan Psaila ◽  
James B. Bussel ◽  
Matthew D. Linden ◽  
Bracken Babula ◽  
Youfu Li ◽  
...  
Keyword(s):  
Platelet Activation ◽  
Platelet Function ◽  
Whole Blood ◽  
Immune Thrombocytopenia ◽  
Ex Vivo ◽  
Platelet Reactivity ◽  
Adenosine Diphosphate ◽  
High Dose ◽  
Platelet Surface

Abstract The effects of eltrombopag, a thrombopoietin-receptor agonist, on platelet function in immune thrombocytopenia (ITP) are not fully characterized. This study used whole blood flow cytometry to examine platelet function in 20 patients receiving eltrombopag treatment at days 0, 7, and 28. Platelet surface expression of activated GPIIb/IIIa, P-selectin, and GPIb was measured with and without low and high adenosine diphosphate (ADP) and thrombin receptor activating peptide (TRAP) concentrations. Before eltrombopag treatment with no ex vivo agonist, platelet activation was higher in ITP patients than controls. Platelet GPIb and activated GPIIb/IIIa expression without added agonist was unchanged following eltrombopag treatment, whereas a slight increase in P-selectin was observed. Expression of P-selectin and activated GPIIb/IIIa in response to high-dose ADP was lower during eltrombopag treatment than at baseline. Eltrombopag led to a slight increase in platelet reactivity to TRAP only in responders to eltrombopag but not to levels above those in controls; whole blood experiments demonstrated that this increase was probably because of higher platelet counts rather than higher platelet reactivity. In conclusion, although thrombocytopenic ITP patients have higher baseline platelet activation than controls, eltrombopag did not cause platelet activation or hyper-reactivity, irrespective of whether the platelet count increased.

The vulnerable blood

2015 ◽  
Vol 35 (01) ◽  
pp. 25-33 ◽  
Author(s):  
K. Hess
Keyword(s):  
Platelet Function ◽  
Plaque Rupture ◽  
Coagulation Factors ◽  
Fibrin Clot ◽  
Clot Lysis ◽  
Complement Components ◽  
Cardiovascular Morbidity And Mortality ◽  
Increased Risk ◽  
Patients With Diabetes ◽  
Clot Structure

SummaryPatients with diabetes are at increased risk of cardiovascular morbidity and mortality. While arteriosclerotic lesions have long been recognized as the underlying cause more recent studies suggest that alterations of the blood are also critically involved. Following plaque rupture, adherence of platelets is followed by the formation of a cross-linked fibrin clot. Patients with diabetes exhibit a prothrombotic milieu consisting of hyper reactive platelets, a tight and rigid clot structure which is due to up-regulation of coagulation factors and prolongation of clot lysis. Metabolic alterations as well as inflammatory processes, which are up–regulated in diabetes, are thought to be the main underlying causes. More recently, the complement cascade has emerged as a potential new player in this context with several complement components directly influencing both platelet function and coagulation.This review provides an overview concerning the changes that lead to alterations of platelet function and clot structure in diabetes.

Mean Corpuscular Volume Predicts Adverse Outcomes Following Peripheral Angioplasty With Stenting and Is Associated With On-Treatment Platelet Reactivity

Angiology ◽  
2020 ◽  
Vol 72 (1) ◽  
pp. 16-23
Author(s):  
Maximilian Tscharre ◽  
Silvia Lee ◽  
Christoph W. Kopp ◽  
Simon Panzer ◽  
Thomas Gremmel
Keyword(s):  
Mean Corpuscular Volume ◽  
Cox Regression ◽  
Light Transmission ◽  
Platelet Reactivity ◽  
Adenosine Diphosphate ◽  
Adverse Outcomes ◽  
Corpuscular Volume ◽  
Characteristic Analysis ◽  
Cox Regression Analysis ◽  
Increased Risk

Structural aspects of red blood cells have been associated with cardiovascular disease. No data linking mean corpuscular volume (MCV) to clinical outcomes and on-treatment platelet reactivity in patients with peripheral artery disease (PAD) are available. We investigated a composite of atherothrombotic events and target vessel restenosis or reocclusion following infrainguinal stenting for stable PAD. Residual platelet reactivity was measured by light transmission aggregometry (LTA) and the VerifyNow assays. We included 104 patients receiving dual antiplatelet therapy (DAPT) with aspirin and clopidogrel. In receiver-operating characteristic analysis, MCV effectively discriminated between patients with and without adverse outcomes and identified a MCV ≤90.8 fL as optimal cutoff. Adverse outcomes occurred significantly more often in patients with low MCV (log-rank P = .002). In univariable Cox regression analysis, low MCV was associated with an increased risk of future adverse outcomes (hazard ratio [HR]: 2.662 [95%CI: 1.304-5.434]; P = .007) and remained significantly associated after adjustment (HR: 2.591 [95%CI: 1.242-5.403]; P = .011). Mean corpuscular volume was inversely correlated with arachidonic acid (AA)- and adenosine diphosphate (ADP)-inducible platelet reactivity by LTA and with the VerifyNow aspirin assay. Low MCV is associated with adverse outcomes over 2 years following infrainguinal stenting. Mean corpuscular volume correlates inversely with AA- and ADP-inducible platelet reactivity during DAPT.

Stability of the high on-treatment platelet reactivity phenotype over time in clopidogrel-treated patients

2011 ◽  
Vol 105 (01) ◽  
pp. 107-112 ◽  
Author(s):  
Juliane Jaitner ◽  
Julia Stegherr ◽  
Tanja Morath ◽  
Siegmund Braun ◽  
Isabell Bernlochner ◽  
...  
Keyword(s):  
Platelet Function ◽  
Large Scale ◽  
Light Transmission ◽  
Platelet Reactivity ◽  
Adenosine Diphosphate ◽  
Antiplatelet Treatment ◽  
Chi Square ◽  
Multiple Electrode Aggregometry ◽  
The Stability ◽  
Over Time

SummaryInterindividual response variability to clopidogrel treatment is a well established phenomenon. In recent studies and ongoing large-scale trials where patients with high on-treatment platelet reactivity (HPR) to clopidogrel are being randomised to an intensified antiplatelet treatment, confirmation of the HPR phenotype is based on one single platelet function assessment. The stability of the HPR phenotype over time has never been investigated but should be considered crucial for justification of intensified antiplatelet treatment regimens beyond clinical trials. The goal of this study was to test for the stability of the HPR phenotype over time in clopidogrel-treated patients. Patients (n=31) under chronic clopidogrel treatment (75 mg/day) were investigated by serial adenosine diphosphate (ADP)-induced platelet aggregation assessment with multiple electrode aggregometry (MEA) on a Multiplate analyser and light transmission aggregometry (LTA) at three different time points (once per week) during monitored antiplatelet treatment. On the basis of a cut-off level approach (468 AU*min for MEA, 53% for LTA) patients were classified into patients with (n=27) or without (n=4) HPR. For MEA, the phenotype was stable in 93.5% (n=29) of patients whereas 6.5% (n=2) crossed the cut-off level. For LTA, the phenotype was stable in 68% (n=21) of patients whereas 32% (n=10) patients crossed the cut-off level (chi-square P=0.01 for comparison of pheno-type stability between both assays). In conclusion, the HPR phenotype is stable over time in the majority of clopidogrel-treated patients. Comparative assessment of phenotype stability across available platelet function assays warrants further investigation.

Individualised Antiplatelet Therapy – Is There a Role for Platelet Function Testing in Routine Clinical Practice?

2010 ◽  
Vol 5 (1) ◽  
pp. 96 ◽  
Author(s):  
Collet Jean-Philippe ◽  
Jochem Wouter van Werkum ◽  
◽  
Keyword(s):  
Clinical Practice ◽  
Antiplatelet Therapy ◽  
Platelet Function ◽  
Platelet Reactivity ◽  
Point Of Care ◽  
Coronary Intervention ◽  
Platelet Function Testing ◽  
Increased Risk ◽  
Coronary Syndromes ◽  
Function Testing

Antiplatelet therapies are often used to minimise complications in patients with acute coronary syndromes or who are undergoing percutaneous coronary intervention with stenting. However, the occurrence of ‘high on-treatment platelet reactivity’ associated with the gold standard treatments aspirin and clopidogrel in a subset of individuals limits the efficacy of these drugs. This lack of response, which has been attributed to a genetic polymorphism, is associated with an increased risk of subsequent atherothrombotic events. In recent years, platelet function assays have been used to monitor antiplatelet inhibition. Various tests have been introduced that allow physicians to evaluate pharmacological response and potentially permit risk stratification of patients. While some of these assays have proved to be labour-intensive, the development of point-of-care assays may ease the time burden in clinical practice. Preliminary findings demonstrate the effectiveness of altering therapy based on assay results in terms of improving clinical outcomes, suggesting an important role for platelet function testing in the future of antiplatelet therapy.

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