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Journal ArticleDOI

Mean platelet volume as a predictor of cardiovascular risk: a systematic review and meta-analysis

TL;DR: See also Machin SJ, Briggs C. Mean platelet volume: a quick, easy determinant of thrombotic risk?
About: This article is published in Journal of Thrombosis and Haemostasis.The article was published on 2010-01-01 and is currently open access. It has received 886 citations till now. The article focuses on the topics: Mean platelet volume & Platelet activation.
Citations
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Journal ArticleDOI
TL;DR: Findings support the existence of a paracrine circuit wherein increased production of thrombopoietic cytokines in tumor and host tissue leads to paraneoplasticThrombocytosis, which fuels tumor growth.
Abstract: From the Departments of Gynecologic Oncology and Reproductive Medicine (R.L.S., A.M.N., H.D.H., J.B.-M., W.H., H.G., K.M., M.M.K.S., E.R.K., A.K.S.), Cancer Biology (R.R., G.L.-B., A.K.S.), Experimental Therapeutics (G.N.A.-P., I.T., B.O., G.L.-B.), Hematology and Oncology (C.V.P.), Pathology (M.T.D.), Benign Hematology (H.G.V., V.A.-K.), Biostatistics (D.U.), and Leukemia (F.G.), and the Center for RNA Interference and Non-Coding RNA (H.D.H., G.L.-B.,

643 citations

Journal ArticleDOI
TL;DR: Understanding how large progenitor cells in the bone marrow called megakaryocytes release platelets occurs is an active area of research with important clinical applications.
Abstract: Circulating blood platelets are specialized cells that prevent bleeding and minimize blood vessel injury. Large progenitor cells in the bone marrow called megakaryocytes (MKs) are the source of platelets. MKs release platelets through a series of fascinating cell biological events. During maturation, they become polyploid and accumulate massive amounts of protein and membrane. Then, in a cytoskeletal-driven process, they extend long branching processes, designated proplatelets, into sinusoidal blood vessels where they undergo fission to release platelets. Given the need for platelets in many pathological situations, understanding how this process occurs is an active area of research with important clinical applications.

593 citations

Journal ArticleDOI
TL;DR: A novel function of SARS-CoV-2 on platelet activation via binding of Spike to ACE2 is uncovered, which may participate in thrombus formation and inflammatory responses in COVID-19 patients.
Abstract: Critically ill patients diagnosed with COVID-19 may develop a pro-thrombotic state that places them at a dramatically increased lethal risk. Although platelet activation is critical for thrombosis and is responsible for the thrombotic events and cardiovascular complications, the role of platelets in the pathogenesis of COVID-19 remains unclear. Using platelets from healthy volunteers, non-COVID-19 and COVID-19 patients, as well as wild-type and hACE2 transgenic mice, we evaluated the changes in platelet and coagulation parameters in COVID-19 patients. We investigated ACE2 expression and direct effect of SARS-CoV-2 virus on platelets by RT-PCR, flow cytometry, Western blot, immunofluorescence, and platelet functional studies in vitro, FeCl3-induced thrombus formation in vivo, and thrombus formation under flow conditions ex vivo. We demonstrated that COVID-19 patients present with increased mean platelet volume (MPV) and platelet hyperactivity, which correlated with a decrease in overall platelet count. Detectable SARS-CoV-2 RNA in the blood stream was associated with platelet hyperactivity in critically ill patients. Platelets expressed ACE2, a host cell receptor for SARS-CoV-2, and TMPRSS2, a serine protease for Spike protein priming. SARS-CoV-2 and its Spike protein directly enhanced platelet activation such as platelet aggregation, PAC-1 binding, CD62P expression, α granule secretion, dense granule release, platelet spreading, and clot retraction in vitro, and thereby Spike protein enhanced thrombosis formation in wild-type mice transfused with hACE2 transgenic platelets, but this was not observed in animals transfused with wild-type platelets in vivo. Further, we provided evidence suggesting that the MAPK pathway, downstream of ACE2, mediates the potentiating role of SARS-CoV-2 on platelet activation, and that platelet ACE2 expression decreases following SARS-COV-2 stimulation. SARS-CoV-2 and its Spike protein directly stimulated platelets to facilitate the release of coagulation factors, the secretion of inflammatory factors, and the formation of leukocyte–platelet aggregates. Recombinant human ACE2 protein and anti-Spike monoclonal antibody could inhibit SARS-CoV-2 Spike protein-induced platelet activation. Our findings uncovered a novel function of SARS-CoV-2 on platelet activation via binding of Spike to ACE2. SARS-CoV-2-induced platelet activation may participate in thrombus formation and inflammatory responses in COVID-19 patients.

461 citations


Cites background from "Mean platelet volume as a predictor..."

  • ...MPV was shown to correlate with platelet activity and is considered a marker of platelet activity [49, 50]; therefore, increased MPV in COVID-19 suggests that these platelets may present as hyperactive....

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Journal ArticleDOI
Christian Gieger, Aparna Radhakrishnan1, Ana Cvejic1, Weihong Tang2  +159 moreInstitutions (46)
08 Dec 2011-Nature
TL;DR: A high-powered meta-analysis of genome-wide association studies (GWAS) in up to 66,867 individuals of European ancestry is carried out, identifying 68 genomic loci reliably associated with platelet count and volume mapping to established and putative novel regulators of megakaryopoiesis and platelet formation.
Abstract: Platelets are the second most abundant cell type in blood and are essential for maintaining haemostasis. Their count and volume are tightly controlled within narrow physiological ranges, but there is only limited understanding of the molecular processes controlling both traits. Here we carried out a high-powered meta-analysis of genome-wide association studies (GWAS) in up to 66,867 individuals of European ancestry, followed by extensive biological and functional assessment. We identified 68 genomic loci reliably associated with platelet count and volume mapping to established and putative novel regulators of megakaryopoiesis and platelet formation. These genes show megakaryocyte-specific gene expression patterns and extensive network connectivity. Using gene silencing in Danio rerio and Drosophila melanogaster, we identified 11 of the genes as novel regulators of blood cell formation. Taken together, our findings advance understanding of novel gene functions controlling fate-determining events during megakaryopoiesis and platelet formation, providing a new example of successful translation of GWAS to function.

424 citations

Journal ArticleDOI
TL;DR: A review of literature reports concerning changes in the mean platelet volume (MPV) and its possible role as a biomarker in inflammatory processes and neoplastic diseases found increased MPV was observed in cardiovascular diseases, cerebral stroke, respiratory diseases, chronic renal failure, intestine diseases, rheumatoid diseases, diabetes, and various cancers.
Abstract: Platelet size has been demonstrated to reflect platelet activity and seems to be a useful predictive and prognostic biomarker of cardiovascular events. It is associated with a variety of prothrombotic and proinflammatory diseases. The aim is a review of literature reports concerning changes in the mean platelet volume (MPV) and its possible role as a biomarker in inflammatory processes and neoplastic diseases. PubMed database was searched for sources using the following keywords: platelet activation, platelet count, mean platelet volume and: inflammation, cancer/tumor, cardiovascular diseases, myocardial infarction, diabetes, lupus disease, rheumatoid arthritis, tuberculosis, ulcerative colitis, renal disease, pulmonary disease, influencing factors, age, gender, genetic factors, oral contraceptives, smoking, lifestyle, methods, standardization, and hematological analyzer. Preference was given to the sources which were published within the past 20 years. Increased MPV was observed in cardiovascular diseases, cerebral stroke, respiratory diseases, chronic renal failure, intestine diseases, rheumatoid diseases, diabetes, and various cancers. Decreased MPV was noted in tuberculosis during disease exacerbation, ulcerative colitis, SLE in adult, and different neoplastic diseases. The study of MPV can provide important information on the course and prognosis in many inflammatory conditions. Therefore, from the clinical point of view, it would be interesting to establish an MPV cut-off value indicating the intensity of inflammatory process, presence of the disease, increased risk of disease development, increased risk of thrombotic complications, increased risk of death, and patient's response on applied treatment. Nevertheless, this aspect of MPV evaluation allowing its use in clinical practice is limited and requires further studies.

268 citations


Cites background from "Mean platelet volume as a predictor..."

  • ...Also, in patients with STEMI infarction, who showed elevated MPV, the application of abciximab decreased mortality [55]....

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  • ...These observations can explain the fact that antiplatelet therapy reduces the risk of complications and in the future also cardiovascular incidents in patients undergoing heart revascularization procedure [55, 63]....

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  • ...Elevated MPV correlates with increased platelet aggregation, enhanced synthesis, and release of thromboxane TXA2 and β-thromboglobulin [55]....

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References
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Journal ArticleDOI
13 Sep 1997-BMJ
TL;DR: Funnel plots, plots of the trials' effect estimates against sample size, are skewed and asymmetrical in the presence of publication bias and other biases Funnel plot asymmetry, measured by regression analysis, predicts discordance of results when meta-analyses are compared with single large trials.
Abstract: Objective: Funnel plots (plots of effect estimates against sample size) may be useful to detect bias in meta-analyses that were later contradicted by large trials. We examined whether a simple test of asymmetry of funnel plots predicts discordance of results when meta-analyses are compared to large trials, and we assessed the prevalence of bias in published meta-analyses. Design: Medline search to identify pairs consisting of a meta-analysis and a single large trial (concordance of results was assumed if effects were in the same direction and the meta-analytic estimate was within 30% of the trial); analysis of funnel plots from 37 meta-analyses identified from a hand search of four leading general medicine journals 1993-6 and 38 meta-analyses from the second 1996 issue of the Cochrane Database of Systematic Reviews . Main outcome measure: Degree of funnel plot asymmetry as measured by the intercept from regression of standard normal deviates against precision. Results: In the eight pairs of meta-analysis and large trial that were identified (five from cardiovascular medicine, one from diabetic medicine, one from geriatric medicine, one from perinatal medicine) there were four concordant and four discordant pairs. In all cases discordance was due to meta-analyses showing larger effects. Funnel plot asymmetry was present in three out of four discordant pairs but in none of concordant pairs. In 14 (38%) journal meta-analyses and 5 (13%) Cochrane reviews, funnel plot asymmetry indicated that there was bias. Conclusions: A simple analysis of funnel plots provides a useful test for the likely presence of bias in meta-analyses, but as the capacity to detect bias will be limited when meta-analyses are based on a limited number of small trials the results from such analyses should be treated with considerable caution. Key messages Systematic reviews of randomised trials are the best strategy for appraising evidence; however, the findings of some meta-analyses were later contradicted by large trials Funnel plots, plots of the trials9 effect estimates against sample size, are skewed and asymmetrical in the presence of publication bias and other biases Funnel plot asymmetry, measured by regression analysis, predicts discordance of results when meta-analyses are compared with single large trials Funnel plot asymmetry was found in 38% of meta-analyses published in leading general medicine journals and in 13% of reviews from the Cochrane Database of Systematic Reviews Critical examination of systematic reviews for publication and related biases should be considered a routine procedure

37,989 citations

Journal ArticleDOI
TL;DR: It is concluded that H and I2, which can usually be calculated for published meta-analyses, are particularly useful summaries of the impact of heterogeneity, and one or both should be presented in publishedMeta-an analyses in preference to the test for heterogeneity.
Abstract: The extent of heterogeneity in a meta-analysis partly determines the difficulty in drawing overall conclusions. This extent may be measured by estimating a between-study variance, but interpretation is then specific to a particular treatment effect metric. A test for the existence of heterogeneity exists, but depends on the number of studies in the meta-analysis. We develop measures of the impact of heterogeneity on a meta-analysis, from mathematical criteria, that are independent of the number of studies and the treatment effect metric. We derive and propose three suitable statistics: H is the square root of the chi2 heterogeneity statistic divided by its degrees of freedom; R is the ratio of the standard error of the underlying mean from a random effects meta-analysis to the standard error of a fixed effect meta-analytic estimate, and I2 is a transformation of (H) that describes the proportion of total variation in study estimates that is due to heterogeneity. We discuss interpretation, interval estimates and other properties of these measures and examine them in five example data sets showing different amounts of heterogeneity. We conclude that H and I2, which can usually be calculated for published meta-analyses, are particularly useful summaries of the impact of heterogeneity. One or both should be presented in published meta-analyses in preference to the test for heterogeneity.

25,460 citations

Journal ArticleDOI
TL;DR: A stepwise description of the tasks that are performed when statistical methods are used to combine data and the question, Are the results of the different studies similar (homogeneous)?
Abstract: The final common pathway for most systematic reviews is a statistical summary of the data, or meta-analysis. The complex methods used in meta-analyses should always be complemented by clinical acumen and common sense in designing the protocol of a systematic review, deciding which data can be combined, and determining whether data should be combined. Both continuous and binary data can be pooled. Most meta-analyses summarize data from randomized trials, but other applications, such as the evaluation of diagnostic test performance and observational studies, have also been developed. The statistical methods of meta-analysis aim at evaluating the diversity (heterogeneity) among the results of different studies, exploring and explaining observed heterogeneity, and estimating a common pooled effect with increased precision. Fixed-effects models assume that an intervention has a single true effect, whereas random-effects models assume that an effect may vary across studies. Meta-regression analyses, by using each study rather than each patient as a unit of observation, can help to evaluate the effect of individual variables on the magnitude of an observed effect and thus may sometimes explain why study results differ. It is also important to assess the robustness of conclusions through sensitivity analyses and a formal evaluation of potential sources of bias, including publication bias and the effect of the quality of the studies on the observed effect.

2,327 citations

Journal ArticleDOI
TL;DR: This review of the role of platelets in at Herothrombosis illuminates the surprisingly numerous activities of these tiny, anucleate cells and stresses their participation in the inflammatory component of atherothromBosis.
Abstract: This review of the role of platelets in atherothrombosis illuminates the surprisingly numerous activities of these tiny, anucleate cells and stresses their participation in the inflammatory component of atherothrombosis. The information is presented in the context of the prevention of atherothrombosis by antiplatelet agents now in clinical use.

1,908 citations

Journal ArticleDOI
TL;DR: This Review highlights the molecular machinery and inflammatory pathways used by platelets to initiate and accelerate atherothrombosis.
Abstract: Platelets represent an important linkage between inflammation, thrombosis, and atherogenesis Inflammation is characterized by interactions among platelets, leukocytes, and ECs These interactions trigger autocrine and paracrine activation processes that lead to leukocyte recruitment into the vascular wall Platelet-induced chronic inflammatory processes at the vascular wall result in development of atherosclerotic lesions and atherothrombosis This Review highlights the molecular machinery and inflammatory pathways used by platelets to initiate and accelerate atherothrombosis

1,293 citations