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Abstract Sudden infant death syndrome (SIDS) is the leading cause of post-neonatal infant mortality, but the underlying cause(s) are unclear. A subset of SIDS infants has abnormalities in the neurotransmitter, serotonin (5-hydroxytryptamine [5-HT]) and the adaptor molecule, 14–3–3 pathways in regions of the brain involved in gasping, response to hypoxia, and arousal. To evaluate our hypothesis that SIDS is, at least in part, a multi-organ dysregulation of 5-HT, we examined whether blood platelets, which have 5-HT and 14–3–3 signaling pathways similar to brain neurons, are abnormal in SIDS. We also studied platelet surface glycoprotein IX (GPIX), a cell adhesion receptor which is physically linked to 14–3–3. In infants dying of SIDS compared to infants dying of known causes, we found significantly higher intra-platelet 5-HT and 14–3–3 and lower platelet surface GPIX. Serum and plasma 5-HT were also elevated in SIDS compared to controls. The presence in SIDS of both platelet and brainstem 5-HT and 14–3–3 abnormalities suggests a global dysregulation of these pathways and the potential for platelets to be used as a model system to study 5-HT and 14–3–3 interactions in SIDS. Platelet and serum biomarkers may aid in the forensic determination of SIDS and have the potential to be predictive of SIDS risk in living infants.

Our objective was to characterize platelet surface glycoprotein (GP)Ibα, activated GPIIb-IIIa, and P-selectin levels during and after extracorporeal membrane oxygenation (ECMO). We performed a single center cohort study of 10 adult patients on ECMO for cardiogenic shock. Patients had blood samples drawn on ECMO day 1 or 2, day 3, day 5, and 48–72 hours after ECMO decannulation. Platelets from untreated blood samples and samples treated with either adenosine diphosphate (ADP) or thrombin receptor agonist peptide (TRAP) had surface GPIbα, activated GPIIb-IIIa, and P-selectin levels measured using flow cytometry. Platelet surface GPIbα levels varied significantly by time on ECMO (p = .002) and were significantly higher on ECMO day 5 compared to ECMO day 1 (p = .01). GPIbα levels during ECMO did not differ significantly from levels after ECMO decannulation (p = .14). Activated GPIIb-IIIa levels did not change significantly during ECMO, but were significantly higher after ECMO decannulation (p = .04). There were no significant differences in P-selectin levels during ECMO (p = .87) or after ECMO decannulation (p = .41). Platelet surface GPIbα and P-selectin levels were similar during and after ECMO whereas activated GPIIb-IIIa levels were lower during ECMO, particularly in response to TRAP stimulation, potentially contributing to ECMO-induced coagulopathy.

Background Patients with single‐ventricle physiology who undergo the Fontan procedure are at risk for thrombotic events associated with significant morbidity and mortality. The UNIVERSE Study evaluated the efficacy and safety of a novel liquid rivaroxaban formulation, using a body weight–adjusted dosing regimen, versus acetylsalicylic acid (ASA) in children post‐Fontan. Methods and Results The UNIVERSE Study was a randomized, multicenter, 2‐part, open‐label study of rivaroxaban, in children who had undergone a Fontan procedure, to evaluate its dosing regimen, safety, and efficacy. Part A was the single‐arm part of the study that determined the pharmacokinetics/pharmacodynamics and safety of rivaroxaban in 12 participants before proceeding to part B, whereby 100 participants were randomized 2:1 to open‐label rivaroxaban versus ASA. The study period was 12 months. A total of 112 participants were enrolled across 35 sites in 10 countries. In part B, for safety outcomes, major bleeding occurred in one participant on rivaroxaban (epistaxis that required transfusion). Clinically relevant nonmajor bleeding occurred in 6% of participants on rivaroxaban versus 9% on ASA. Trivial bleeding occurred in 33% of participants on rivaroxaban versus 35% on ASA. For efficacy outcomes, 1 participant on rivaroxaban in part B had a pulmonary embolism (2% overall event rate); and for ASA, 1 participant had ischemic stroke and 2 had venous thrombosis (9% overall event rate). Conclusions In this study, participants who received rivaroxaban for thromboprophylaxis had a similar safety profile and fewer thrombotic events, albeit not statistically significant, compared with those in the ASA group. Registration URL: https://www.clinicaltrials.gov. Identifier: NCT02846532.