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Recurrent croup is a common clinical entity afflicting the pediatric population, but is not well-characterized in the literature. We describe the largest series of recurrent croup in North America from a single tertiary care academic center, and differentiate subpopulations based on demographic characteristics and clinical presentation. We identified 114 patients for inclusion. Common symptoms included barky cough (86.0%) and inspiratory stridor (60.5%). Many (26.3%) experienced full symptom resolution within a day, and 41.2% reported onset of symptoms at any time of the day. Male patients had a higher number of prior croup episodes at presentation compared with female patients (mean of 9.8 ± 8.0 in males vs 6.6 ± 4.8 in females, P = .03). On multivariate regression, racial/ethnic minority patients were at higher risk for dyspnea (odds ratio [OR]: 58.6; 95% confidence interval [CI]: 7.2-475.4) and upper respiratory infection prodrome (OR: 7.6; 95% CI: 1.6-35.3) compared with non-Hispanic white patients.

To determine how commonly word recognition scores obtained using insert microphones (PB max) overestimate word recognition scores obtained through appropriately fit hearing aids (A-WRS).Aided speech recognition tests may not be performed during routine hearing aid fittings; however, they are regularly performed for cochlear implant (CI) candidacy evaluation. Therefore, audiologic data from CI recipients were queried in a retrospective cohort study at a tertiary care center. PB max and A-WRS were obtained. The Speech Perception (SP) gap, defined as PB max minus A-WRS, was calculated for each patient and a high SP gap was defined as ≥20%.Analyzing 78 patients with complete data, 30 patients had PB max ≥20%. Of these, 18 (60%) had a high SP gap. Eighteen of the 78 patients had PB max ≥40%, and of these patients, 15 (83%) had a high SP gap.A Speech Perception Gap of ≥20% may exist in a sizable percentage of patients with hearing loss. Our pilot study suggests that over 80% of these patients could have Class D hearing (speech recognition50%) using conventional hearing aids and may be better served using alternate rehabilitation strategies such as middle ear or cochlear implants. Therefore, aided speech testing should be performed as part of a verified hearing aid fit in all patients, especially those with PB Max ranging from 40% to 70%.

Dysregulated inflammation is implicated in the pathobiology of aging, yet platelet–leukocyte interactions and downstream cytokine synthesis in aging remains poorly understood. Platelets and monocytes were isolated from healthy younger (age

Objective— Blood vessel wall damage often results in the formation of a fibrin clot that traps inflammatory cells, including monocytes. The effect of clot formation and subsequent lysis on the expression of monocyte-derived genes involved in the development and progression of ischemic stroke and other vascular diseases, however, is unknown. Determine whether clot formation and lysis regulates the expression of human monocyte-derived genes that modulate vascular diseases. Approach and Results— We performed next-generation RNA sequencing on monocytes extracted from whole blood clots and using a purified plasma clot system. Numerous mRNAs were differentially expressed by monocytes embedded in clots compared with unclotted controls, and IL-8 (interleukin 8) and MCP-1 (monocyte chemoattractant protein-1) were among the upregulated transcripts in both models. Clotted plasma also increased expression of IL-8 and MCP-1, which far exceeded responses observed in lipopolysaccharide-stimulated monocytes. Upregulation of IL-8 and MCP-1 occurred in a thrombin-independent but fibrin-dependent manner. Fibrinolysis initiated shortly after plasma clot formation (ie, 1–2 hours) reduced the synthesis of IL-8 and MCP-1, whereas delayed fibrinolysis was far less effective. Consistent with these in vitro models, monocytes embedded in unresolved thrombi from patients undergoing thrombectomy stained positively for IL-8 and MCP-1. Conclusions— These findings demonstrate that clots are potent inducers of monocyte gene expression and that timely fibrinolysis attenuates inflammatory responses, specifically IL-8 and MCP-1. Dampening of inflammatory gene expression by timely clot lysis may contribute to the clinically proven efficacy of fibrinolytic drug treatment within hours of stroke onset.

Essentials Platelets employ proteins/signaling pathways traditionally thought reserved for nuclear niche. We determined retinoic-acid-receptor alpha (RARα) expression and function in human platelets. RARα/actin-related protein-2/3 complex (Arp2/3) interact via non-genomic signaling in platelets. RARα regulates Arp2/3-mediated actin cytoskeletal dynamics and platelet spreading. SummaryBackground Platelets utilize proteins and pathways classically reserved for the nuclear niche. Methods We determined whether human platelets express retinoic-acid-receptor family members, traditionally thought of as nuclear transcription factors, and deciphered the function of RARα. Results We found that RARα is robustly expressed in human platelets and megakaryocytes and interacts directly with actin-related protein-2/3 complex (Arp2/3) subunit 5 (Arp2/3s5). Arp2/3s5 co-localized with RARα in situ and regulated platelet cytoskeletal processes. The RARα ligand all-trans retinoic acid (atRA) disrupted RARα‒Arp2/3 interactions. When isolated human platelets were treated with atRA, rapid cytoskeletal events (e.g. platelet spreading) were inhibited. In addition, when platelets were cultured for 18 h in the presence of atRA, actin-dependent morphological changes (e.g. extended cell body formation) were similarly inhibited. Using in vitro actin branching assays, RARα and Arp2/3-regulated complex actin branch formation was demonstrated. Consistent with inhibition of cytoskeletal processes in platelets, atRA, when added to this branching assay, resulted in dysregulated actin branching. Conclusion Our findings identify a previously unknown mechanism by which RARα regulates Arp2/3-mediated actin cytoskeletal dynamics through a non-genomic signaling pathway. These findings have broad implications in both nucleated and anucleate cells, where actin cytoskeletal events regulate cell morphology, movement and division.

Objectives Cigarette smoking and passive smoke exposure have been associated with chronic rhinosinusitis (CRS). Our goal in this systematic review was to (1) determine if there was a strong correlative effect in large population studies between cigarette smoke exposure and the prevalence of CRS, (2) investigate pathogenic mechanisms of cigarette smoke in the upper airway, and (3) determine if a history of cigarette smoking affects the medical and surgical outcomes of CRS. Data Sources MEDLINE, Embase, Cochrane CENTRAL, Web of Science SCI and CPCI-S, and websites. Methods A comprehensive literature review and quantitative meta-analysis of studies based on the PRISMA protocol and examining the relationship between cigarette smoke exposure and CRS was performed. A search strategy was developed using various terms such as sinusitis, rhinitis, rhinosinusitis, and smoking. The articles were categorized by (1) epidemiology, (2) pathophysiology, and (3) outcomes. Data regarding study design, population/setting, methods, and bias were collected. Results The initial search generated 2621 titles/abstracts with 309 articles undergoing secondary review and 112 articles for final review. We determined that there is a strong correlation between active and passive cigarette smoke with the prevalence of CRS. Cigarette smoke challenge to sinonasal epithelia results in the release of inflammatory mediators and altered ciliary beat frequency. Pediatric patients exposed to secondhand smoke appear to have particularly poor outcomes. Conclusion There is clear evidence that cigarette smoke is related to CRS, but longitudinal and mechanistic studies are required to determine a causative effect. This information is critical for greater understanding of CRS health outcomes.

SummaryMethicillin-resistant Staphylococcus aureus (MRSA) induces a prothrombotic and pro-inflammatory milieu. Although timely antibiotic administration in MRSA sepsis may improve outcomes by arresting bacterial growth, the effects of antibiotics on mitigating injurious thrombo-inflammatory cellular responses remains unexplored. Using a newly developed human whole blood model and an in vivo mouse model of MRSA infection, we examined how antibiotics inhibit MRSA induced thrombo-inflammatory pathways. Human whole blood was inoculated with MRSA. Thrombin generation and inflammatory cytokine synthesis was measured in the presence or absence of linezolid and vancomycin. C57BL/6 mice were injected with MRSA and the effect of vancomycin administration was examined. MRSA accelerated thrombin generation in a time- and concentration-dependent manner and induced the release of cytokines, including interleukin (IL)-6, IL-8, and monocyte chemotactic protein (MCP)-1. The increase in thrombin generation and inflammatory responses was mediated through the synthesis of tissue factor and cytokines, respectively, and the release of microparticles. The early administration of antibiotics restored normal thrombin generation patterns and significantly reduced the synthesis of cytokines. In contrast, when antibiotic administration was delayed, thrombin generation and cytokine synthesis were not significantly reduced. In mice infected with MRSA, early antibiotic administration reduced thrombin anti-thrombin complexes and cytokine synthesis, whereas delayed antibiotic administration did not. These data provide novel mechanistic evidence of the importance of prompt antibiotic administration in infectious syndromes.

Bacteria can enter the bloodstream in response to infectious insults. Bacteremia elicits several immune and clinical complications, including thrombocytopenia. A primary cause of thrombocytopenia is shortened survival of platelets. We demonstrate that pathogenic bacteria induce apoptotic events in platelets that include calpain-mediated degradation of Bcl-xL, an essential regulator of platelet survival. Specifically, bloodstream bacterial isolates from patients with sepsis induce lateral condensation of actin, impair mitochondrial membrane potential, and degrade Bcl-xL protein in platelets. Bcl-xL protein degradation is enhanced when platelets are exposed to pathogenic Escherichia coli that produce the pore-forming toxin α-hemolysin, a response that is markedly attenuated when the gene is deleted from E coli. We also found that nonpathogenic E coli gain degrading activity when they are forced to express α-hemolysin. Like α-hemolysin, purified α-toxin readily degrades Bcl-xL protein in platelets, as do clinical Staphylococcus aureus isolates that produce α-toxin. Inhibition of calpain activity, but not the proteasome, rescues Bcl-xL protein degradation in platelets coincubated with pathogenic E coli including α-hemolysin producing strains. This is the first evidence that pathogenic bacteria can trigger activation of the platelet intrinsic apoptosis program and our results suggest a new mechanism by which bacterial pathogens might cause thrombocytopenia in patients with bloodstream infections.

Stroke is a common and often fatal event, and, in survivors, it is accompanied by a high risk of recurrence. Ischemic stroke is associated with abnormal platelet activity and thrombus formation. In addition to their roles in the development of acute thrombi, platelets serve as a bridge for leukocytes within the vasculature. Myeloid leukocytes are critical mediators of atherosclerosis and atherothrombosis. Interactions between platelets and leukocytes foster an inflammatory and thrombotic milieu that influences lesion progression, facilitates plaque rupture, and triggers thrombus formation and embolization. Accordingly, antiplatelet agents, including aspirin, dipyridamole, and clopidogrel, are recommended therapies for most patients with a history of stroke. In addition to mitigating thrombosis, antiplatelet drugs have direct and indirect effects on inflammation, which may translate to enhanced clinical efficacy.

OBJECTIVES/SPECIFIC AIMS: Platelets govern signal-dependent inflammatory responses by leukocytes. Although dysregulated inflammation is common in older adults, platelet-leukocyte signaling events and downstream inflammatory gene synthesis in aging is not known. METHODS/STUDY POPULATION: Highly-purified platelets and monocytes were isolated from healthy older (age>60, n=27) and younger (agepp

Poly(amidoamine) (PAMAM) dendrimers have been proposed for a variety of biomedical applications and are increasingly studied as model nanomaterials for such use. The dendritic structure features both modular synthetic control of molecular size and shape and presentation of multiple equivalent terminal groups. These properties make PAMAM dendrimers highly functionalizable, versatile single-molecule nanoparticles with a high degree of consistency and low polydispersity. Recent nanotoxicological studies showed that intravenous administration of amine-terminated PAMAM dendrimers to mice was lethal, causing a disseminated intravascular coagulation-like condition. To elucidate the mechanisms underlying this coagulopathy, in vitro assessments of platelet functions in contact with PAMAM dendrimers were undertaken. This study demonstrates that cationic G7 PAMAM dendrimers activate platelets and dramatically alter their morphology. These changes to platelet morphology and activation state substantially altered platelet function, including increased aggregation and adherence to surfaces. Surprisingly, dendrimer exposure also attenuated platelet-dependent thrombin generation, indicating that not all platelet functions remained intact. These findings provide additional insight into PAMAM dendrimer effects on blood components and underscore the necessity for further research on the effects and mechanisms of PAMAM-specific and general nanoparticle toxicity in blood.

Human β-defensins (hBD) are antimicrobial peptides that curb microbial activity. Although hBD's are primarily expressed by epithelial cells, we show that human platelets express hBD-1 that has both predicted and novel antibacterial activities. We observed that activated platelets surround Staphylococcus aureus (S. aureus), forcing the pathogens into clusters that have a reduced growth rate compared to S. aureus alone. Given the microbicidal activity of β-defensins, we determined whether hBD family members were present in platelets and found mRNA and protein for hBD-1. We also established that hBD-1 protein resided in extragranular cytoplasmic compartments of platelets. Consistent with this localization pattern, agonists that elicit granular secretion by platelets did not readily induce hBD-1 release. Nevertheless, platelets released hBD-1 when they were stimulated by α-toxin, a S. aureus product that permeabilizes target cells. Platelet-derived hBD-1 significantly impaired the growth of clinical strains of S. aureus. hBD-1 also induced robust neutrophil extracellular trap (NET) formation by target polymorphonuclear leukocytes (PMNs), which is a novel antimicrobial function of β-defensins that was not previously identified. Taken together, these data demonstrate that hBD-1 is a previously-unrecognized component of platelets that displays classic antimicrobial activity and, in addition, signals PMNs to extrude DNA lattices that capture and kill bacteria., Author Summary Platelets are small cells in the bloodstream whose primary function is to stop bleeding. In addition to their clotting functions, we show that human platelets stall bacterial growth. This inhibitory property of platelets is due to β-defensin 1, a small antimicrobial protein that kills bacteria. β-defensin 1 also induces white blood cells to discharge spider-like webs that trap and kill bacteria. Together, these findings indicate that human platelets use β-defensin 1 to fight off bacterial infection.