=====Coated platelets=====
Coated-[[platelet]]s, formerly known as COAT-platelets, represent a subpopulation of cells observed after dual agonist stimulation of platelets with [[collagen]] and [[thrombin]]. This class of platelets retains on its surface high levels of several procoagulant proteins, including fibrinogen, von Willebrand factor, fibronectin, factor V and thrombospondin. Coated-platelets also express surface phosphatidylserine and strongly support prothrombinase activity. Retention of alpha-granule proteins on the surface of coated-platelets involves an unexpected derivatization of these proteins with serotonin and an interaction of serotonin-conjugated proteins with serotonin binding sites on fibrinogen and thrombospondin
((Dale GL. Coated-platelets: an emerging component of the procoagulant response.
J Thromb Haemost. 2005 Oct;3(10):2185-92. Review. PubMed PMID: 16194197.
)).
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[[Prothrombotic state]]s of early brain injury (EBI) and [[delayed cerebral ischemia]] (DCI) after aSAH determine morbidity and mortality. To understand how [[platelet activation]] might contribute to such prothrombotic states, Ray et al. studied trends in [[coated platelets]] during EBI and DCI periods. Serial blood samples from a prospective cohort of aSAH patients were collected and assayed for coated-platelet levels. Patient's coated-platelet level during post-hospital discharge follow-up served as an estimate of baseline. Occurrence of DCI, Montreal cognitive assessment (MOCA) score of < 26, and modified Rankin scale (mRS) of 3-6 were considered poor clinical outcomes. Non-linear regression analysis detected a transition between periods of rising and declining coated-platelet levels at day 4. Additional regression analyses of coated-platelet trends before day 4 showed differences among patients with modified Fisher 3-4 [4.2% per day (95% CI 2.4, 6.1) vs. - 0.8% per day (95% CI - 3.4, 1.8); p = 0.0023] and those developing DCI [4.6% per day (95% CI 2.8, 6.5) vs. - 1.9% per day (95% CI - 4.5, 0.5); p < 0.001]. Differences between peak coated-platelet levels and baseline levels were larger, on average for those with DCI [18.1 ± 9.6 vs. 10.6 ± 8.0; p = 0.03], MOCA < 26 [17.0 ± 7.8 vs. 10.7 ± 7.4; p = 0.05] and mRS 3-6 [24.8 ± 10.5 vs. 11.9 ± 7.6; p = 0.01]. Coated-platelet trends after aSAH predict DCI and short-term clinical outcomes. The degree of rise in coated-platelets is also associated with adverse clinical outcomes
((Ray B, Pandav VM, Mathews EA, Thompson DM, Ford L, Yearout LK, Bohnstedt BN,
Chaudhary S, Dale GL, Prodan CI. Coated-Platelet Trends Predict Short-Term
Clinical OutcomeAfter Subarachnoid Hemorrhage. Transl Stroke Res. 2017 Dec 9.
doi: 10.1007/s12975-017-0594-7. [Epub ahead of print] PubMed PMID: 29224114.
)).