High Variability in the Duration of Chest Compression Interruption is Associated With Poor Outcomes in Pediatric Extracorporeal Cardiopulmonary Resuscitation

OBJECTIVES

To determine the association between chest compression interruption (CCI) patterns and outcomes in pediatric patients undergoing extracorporeal cardiopulmonary resuscitation (ECPR).

DESIGN

Cardiopulmonary resuscitation (CPR) data were collected using defibrillator-electrode and bedside monitor waveforms from pediatric ECPR cases between 2013 and 2021. Duration and variability of CCI during cannulation for ECPR was determined and compared with survival to discharge using Fishers exact test and logistic regressions with cluster-robust se s for adjusted analyses.

SETTING

Quaternary care children's hospital.

PATIENTS

Pediatric patients undergoing ECPR.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of 41 ECPR events, median age was 0.7 years (Q1, Q3: 0.1, 5.4), 37% (15/41) survived to hospital discharge with 73% (11/15) of survivors having a favorable neurologic outcome. Median duration of CPR from start of ECPR cannulation procedure to initiation of extracorporeal membrane oxygenation (ECMO) flow was 21 minutes (18, 30). Median duration of no-flow times associated with CCI during ECMO cannulation was 11 seconds (5, 28). Following planned adjustment for known confounders, survival to discharge was inversely associated with maximum duration of CCI (odds ratio [OR] 0.91 [0.86-0.95], p = 0.04) as well as the variability in the CCI duration (OR 0.96 [0.93-0.99], p = 0.04). Cases with both above-average CCI duration and higher CCI variability ( sd > 30 s) were associated with lowest survival (12% vs. 54%, p = 0.009). Interaction modeling suggests that lower variability in CCI is associated with improved survival, especially in cases where average CCI durations are higher.

CONCLUSIONS

Shorter duration of CCI and lower variability in CCI during cannulation for ECPR were associated with survival following refractory pediatric cardiac arrest.

Rejecting Reforms, Yet Calling for Change: A Qualitative Analysis of Proposed Reforms to the Residency Application Process

PURPOSE

Annual increases in the number of residency applications burden students and challenge programs. Several reforms to the application process have been proposed; however, stakeholder input is often overlooked. The authors examined key stakeholders' opinions about several proposed reforms to the residency application process and identified important factors to guide future reforms.

METHOD

Using semistructured interviews, the authors asked educational administrators and trainees to consider 5 commonly proposed reforms to the residency application process: Match to obtain residency interviews, preference signaling, application limits, geographic preference disclosure, and abolishing the Match. The authors conducted a modified content analysis of interview transcripts using qualitative and quantitative analytic techniques. Frequency analysis regarding the acceptability of the 5 proposed reforms and thematic analysis of important factors to guide reform were performed. Fifteen-minute interviews were conducted between July and October 2019, with data analysis completed during a 6-month period in 2020 and 2021.

RESULTS

Participants included 30 stakeholders from 9 medical specialties and 15 institutions. Most participants wanted to keep the Match process intact; however, they noted several important flaws in the system that disadvantage students and warrant change. Participants did not broadly support any of the 5 proposed reforms. Two themes were identified: principles to guide reform (fairness, transparency, equity, reducing costs to students, reducing total applications, reducing work for program directors, and avoiding unintended consequences) and unpopular reform proposals (concern that application limits threaten less competitive students and signaling adds bias to the system).

CONCLUSIONS

Key stakeholders in the residency application process believe the system has important flaws that demand reform. Despite this, the most commonly proposed reforms are unacceptable to these stakeholders because they threaten fairness to students and program workload. These findings call for a larger investigation of proposed reforms with a more nationally representative stakeholder cohort.

The Summer Match: A qualitative study exploring a two-stage residency match option

BACKGROUND

The number of residency applications submitted by medical students rises annually, resulting in increased work and costs for residency programs and applicants, particularly in emergency medicine. We propose a solution to this problem: an optional, two-stage Match with a "summer match" stage, in which applicants can submit a limited number of applications early. This would be conducted similarly to the early decision process for college admissions. The study objectives were to explore stakeholder opinions on the feasibility of a summer match and to identify the ideal logistic parameters to operationalize this proposal.

METHODS

We used exploratory qualitative methodology following a constructivist paradigm to develop an understanding of the potential impact of a summer match. We interviewed 34 key stakeholders in the U.S. residency application process identified through purposive sampling including educational administrators (program directors, designated institutional officials, medical school deans) and trainees (students, residents). We coded and thematically analyzed interview data in two stages using an inductive approach.

RESULTS

We identified six themes from the participant interviews that broadly reflected issues of the residency application process, value, and equity. These themes included disrupting the status quo, logistic concerns, match strategy, differential benefits, unintended consequences, and return on investment. Most study participants supported the summer match concept, with medical students and residents most in favor. We developed a theoretical summer match protocol based on these findings.

CONCLUSIONS

A summer match may reduce the burdens of increasing residency applications and associated costs. Pilot testing is necessary to confirm this hypothesis and determine the impact of the proposed summer match protocol. Unintended consequences must be considered carefully during implementation.

Molecular mechanisms of coronary disease revealed using quantitative trait loci for TCF21 binding, chromatin accessibility, and chromosomal looping

BACKGROUND

To investigate the epigenetic and transcriptional mechanisms of coronary artery disease (CAD) risk, as well as the functional regulation of chromatin structure and function, we create a catalog of genetic variants associated with three stages of transcriptional cis-regulation in primary human coronary artery vascular smooth muscle cells (HCASMCs).

RESULTS

We use a pooling approach with HCASMC lines to map regulatory variants that mediate binding of the CAD-associated transcription factor TCF21 with ChIPseq studies (bQTLs), variants that regulate chromatin accessibility with ATACseq studies (caQTLs), and chromosomal looping with Hi-C methods (clQTLs). We examine the overlap of these QTLs and their relationship to smooth muscle-specific genes and transcription factors. Further, we use multiple analyses to show that these QTLs are highly associated with CAD GWAS loci and correlate to lead SNPs where they show allelic effects. By utilizing genome editing, we verify that identified functional variants can regulate both chromatin accessibility and chromosomal looping, providing new insights into functional mechanisms regulating chromatin state and chromosomal structure. Finally, we directly link the disease-associated TGFB1-SMAD3 pathway to the CAD-associated FN1 gene through a response QTL that modulates both chromatin accessibility and chromosomal looping.

CONCLUSIONS

Together, these studies represent the most thorough mapping of multiple QTL types in a highly disease-relevant primary cultured cell type and provide novel insights into their functional overlap and mechanisms that underlie these genomic features and their relationship to disease risk.

Fine-mapping cis-regulatory variants in diverse human populations

Genome-wide association studies (GWAS) are a powerful approach for connecting genotype to phenotype. Most GWAS hits are located in cis-regulatory regions, but the underlying causal variants and their molecular mechanisms remain unknown. To better understand human cis-regulatory variation, we mapped quantitative trait loci for chromatin accessibility (caQTLs)—a key step in cis-regulation—in 1000 individuals from 10 diverse populations. Most caQTLs were shared across populations, allowing us to leverage the genetic diversity to fine-map candidate causal regulatory variants, several thousand of which have been previously implicated in GWAS. In addition, many caQTLs that affect the expression of distal genes also alter the landscape of long-range chromosomal interactions, suggesting a mechanism for long-range expression QTLs. In sum, our results show that molecular QTL mapping integrated across diverse populations provides a high-resolution view of how worldwide human genetic variation affects chromatin accessibility, gene expression, and phenotype.

Editorial note: This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that minor issues remain unresolved (see decision letter).

Genomic survey of premetazoans shows deep conservation of cytoplasmic tyrosine kinases and multiple radiations of receptor tyrosine kinases

The evolution of multicellular metazoans from a unicellular ancestor is one of the most important advances in the history of life. Protein tyrosine kinases play important roles in cell-to-cell communication, cell adhesion, and differentiation in metazoans; thus, elucidating their origins and early evolution is crucial for understanding the origin of metazoans. Although tyrosine kinases exist in choanoflagellates, few data are available about their existence in other premetazoan lineages. To unravel the origin of tyrosine kinases, we performed a genomic and polymerase chain reaction (PCR)-based survey of the genes that encode tyrosine kinases in the two described filasterean species, Capsaspora owczarzaki and Ministeria vibrans, the closest relatives to the Metazoa and Choanoflagellata clades. We present 103 tyrosine kinase-encoding genes identified in the whole genome sequence of C. owczarzaki and 15 tyrosine kinase-encoding genes cloned by PCR from M. vibrans. Through detailed phylogenetic analysis, comparison of the organizations of the protein domains, and resequencing and revision of tyrosine kinase sequences previously found in some whole genome sequences, we demonstrate that the basic repertoire of metazoan cytoplasmic tyrosine kinases was established before the divergence of filastereans from the Metazoa and Choanoflagellata clades. In contrast, the receptor tyrosine kinases diversified extensively in each of the filasterean, choanoflagellate, and metazoan clades. This difference in the divergence patterns between cytoplasmic tyrosine kinases and receptor tyrosine kinases suggests that receptor tyrosine kinases that had been used for receiving environmental cues were subsequently recruited as a communication tool between cells at the onset of metazoan multicellularity.

The minimal kinome of Giardia lamblia illuminates early kinase evolution and unique parasite biology

Background

The major human intestinal pathogen Giardia lamblia is a very early branching eukaryote with a minimal genome of broad evolutionary and biological interest.

Results

To explore early kinase evolution and regulation of Giardia biology, we cataloged the kinomes of three sequenced strains. Comparison with published kinomes and those of the excavates Trichomonas vaginalis and Leishmania major shows that Giardia's 80 core kinases constitute the smallest known core kinome of any eukaryote that can be grown in pure culture, reflecting both its early origin and secondary gene loss. Kinase losses in DNA repair, mitochondrial function, transcription, splicing, and stress response reflect this reduced genome, while the presence of other kinases helps define the kinome of the last common eukaryotic ancestor. Immunofluorescence analysis shows abundant phospho-staining in trophozoites, with phosphotyrosine abundant in the nuclei and phosphothreonine and phosphoserine in distinct cytoskeletal organelles. The Nek kinase family has been massively expanded, accounting for 198 of the 278 protein kinases in Giardia. Most Neks are catalytically inactive, have very divergent sequences and undergo extensive duplication and loss between strains. Many Neks are highly induced during development. We localized four catalytically active Neks to distinct parts of the cytoskeleton and one inactive Nek to the cytoplasm.

Conclusions

The reduced kinome of Giardia sheds new light on early kinase evolution, and its highly divergent sequences add to the definition of individual kinase families as well as offering specific drug targets. Giardia's massive Nek expansion may reflect its distinctive lifestyle, biphasic life cycle and complex cytoskeleton.

The Selaginella genome identifies genetic changes associated with the evolution of vascular plants

Vascular plants appeared ~410 million years ago, then diverged into several lineages of which only two survive: the euphyllophytes (ferns and seed plants) and the lycophytes. We report here the genome sequence of the lycophyte Selaginella moellendorffii (Selaginella), the first nonseed vascular plant genome reported. By comparing gene content in evolutionarily diverse taxa, we found that the transition from a gametophyte- to a sporophyte-dominated life cycle required far fewer new genes than the transition from a nonseed vascular to a flowering plant, whereas secondary metabolic genes expanded extensively and in parallel in the lycophyte and angiosperm lineages. Selaginella differs in posttranscriptional gene regulation, including small RNA regulation of repetitive elements, an absence of the trans-acting small interfering RNA pathway, and extensive RNA editing of organellar genes.