This work explores whether human transposons from the L1 family of retrotransposons are active in human neural stem cells derived from various sources. This work explores both the characteristics of cells which allow L1 retrotransposition and the insertional characteristics of the L1 within those cells. Not only did human neural stem cells allow for retrotransposition, they reproducibly exhibited robust rates of insertion. In these studies I also develop a technique for analyzing the copy number of endogenous L1s and discover evidence for endogenous retrotransposition in the human brain, notably in the hippocampus. To begin to investigate the mechanism of L1 retrotransposition, methylation analysis of the L1 promoter within the 5' untranslated region (UTR) was undertaken using human developmental tissues. The outcome indicated decreased methylation of the L1 promoter in the brain as compared to the skin across many genomic L1s. Moreover, this work seeks to investigate how L1 retrotransposition in the brain might be affected in a neurological disease process. Ataxia telangiectasia (AT) is an autosomal recessive disorder characterized by neurological degeneration and a mutation in the ATM (ataxia telangiectasia mutated) gene. In these studies we found that a transgenic mouse model of AT exhibits increased retrotransposition, as do human neural stem cells in the absence of ATM. These findings further support earlier studies showing L1 retrotransposition in the mouse brain and contribute to our understanding of the activity of L1 in nervous system. Furthermore, they propose that L1 retrotransposition may be aberrantly increased in the context of neurological disease. Finally, this work suggests multiple additional research pathways for investigating the mechanism and potential consequences of L1 retrotransposition in the nervous system

We report a rare aetiology of vocal cord paralysis secondary to undiagnosed severe pulmonary hypertension from a de novo ACVRL1 variant identified by whole-genome sequencing. The patient had a partial response to intravenous treprostinil in addition to inhaled nitric oxide, bosentan, and sildenafil.

Microglia, the resident macrophage of the central nervous system, are increasingly recognized as contributing to diverse aspects of human development, health, and disease. In recent years, numerous studies in both mouse and human models have identified microglia as a double edged sword in the progression of neurotropic viral infections: protecting against viral replication and cell death in some contexts, while acting as viral reservoirs and promoting excess cellular stress and cytotoxicity in others. It is imperative to understand the diversity of human microglial responses in order to therapeutically modulate them; however, modeling human microglia has been historically challenging due to significant interspecies differences in innate immunity and rapid transformation upon in vitro culture. In this review, we discuss the contribution of microglia to the neuropathogenesis of key neurotropic viral infections: human immunodeficiency virus 1 (HIV-1), Zika virus (ZIKV), Japanese encephalitis virus (JEV), West Nile virus (WNV), Herpes simplex virus (HSV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We pay special attention to recent work with human stem cell-derived microglia and propose strategies to leverage these powerful models to further uncover species- and disease-specific microglial responses and novel therapeutic interventions for neurotropic viral infections.

Severe cases of hydrocarbon aspiration requiring Extracorporeal Membrane Oxygenation (ECMO) are rarely reported in pediatrics, and 90% of hospitalized patients have a relatively benign clinical course. We describe a 14 month-old female with accidental hydrocarbon ingestion and aspiration due to organic makeup brush cleaner that suffered severe ARDS and multiorgan failure, successfully managed with ECMO and surfactant. She was decannulated after a total of 72 hours on ECMO, extubated on hospital day 15 (HD 15), and discharged home in her normal state of health after one month in the hospital. ECMO and adjunctive therapies such as surfactant may be helpful in the management of severe hydrocarbon pneumonitis and there are limited reports of ECMO as a supportive method for these pediatric patients.

Objectives

To determine the frequency and characteristics of complications of peripherally administered hypertonic saline (HTS) through assessment of infiltration and extravasation.

Design

Retrospective cross-sectional study.

Setting

Freestanding tertiary care pediatric hospital.

Patients

Children who received HTS through a peripheral IV catheter (PIVC).

Interventions

None.

Measurements and main results

We conducted a single-center retrospective review from January 2012 to 2019. A total of 526 patients with 1,020 unique administrations of HTS through a PIVC met inclusion criteria. The primary endpoint was PIVC failure due to infiltration or extravasation. The indication for the administration of HTS infusion was collected. Catheter data was captured, including the setting of catheter placement, anatomical location on the patient, gauge size, length of time from catheter insertion to HTS infusion, in situ duration of catheter lifespan, and removal rationale. The administration data for HTS was reviewed and included volume of administration, bolus versus continuous infusion, infusion rate, infusion duration, and vesicant medications administered through the PIVC. There were 843 bolus infusions of HTS and 172 continuous infusions. Of the bolus administrations, there were eight infiltrations (0.9%). The continuous infusion group had 13 infiltrations (7.6%). There were no extravasations in either group, and no patients required medical therapy or intervention by the wound care or plastic surgery teams. There was no significant morbidity attributed to HTS administration in either group.

Conclusions

HTS administered through a PIVC infrequently infiltrates in critically ill pediatric patients. The infiltration rate was low when HTS is administered as a bolus but higher when given as a continuous infusion. However, no patient suffered an extravasation injury or long-term morbidity from any infiltration.

Long interspersed nuclear elements-1 (LINE-1 or L1s) are abundant retrotransposons that comprise approximately 20% of mammalian genomes. Active L1 retrotransposons can impact the genome in a variety of ways, creating insertions, deletions, new splice sites or gene expression fine-tuning. We have shown previously that L1 retrotransposons are capable of mobilization in neuronal progenitor cells from rodents and humans and evidence of massive L1 insertions was observed in adult brain tissues but not in other somatic tissues. In addition, L1 mobility in the adult hippocampus can be influenced by the environment. The neuronal specificity of somatic L1 retrotransposition in neural progenitors is partially due to the transition of a Sox2/HDAC1 repressor complex to a Wnt-mediated T-cell factor/lymphoid enhancer factor (TCF/LEF) transcriptional activator. The transcriptional switch accompanies chromatin remodelling during neuronal differentiation, allowing a transient stimulation of L1 transcription. The activity of L1 retrotransposons during brain development can have an impact on gene expression and neuronal function, thereby increasing brain-specific genetic mosaicism. Further understanding of the molecular mechanisms that regulate L1 expression should provide new insights into the role of L1 retrotransposition during brain development. Here we show that L1 neuronal transcription and retrotransposition in rodents are increased in the absence of methyl-CpG-binding protein 2 (MeCP2), a protein involved in global DNA methylation and human neurodevelopmental diseases. Using neuronal progenitor cells derived from human induced pluripotent stem cells and human tissues, we revealed that patients with Rett syndrome (RTT), carrying MeCP2 mutations, have increased susceptibility for L1 retrotransposition. Our data demonstrate that L1 retrotransposition can be controlled in a tissue-specific manner and that disease-related genetic mutations can influence the frequency of neuronal L1 retrotransposition. Our findings add a new level of complexity to the molecular events that can lead to neurological disorders.

Background

Congenital heart defects (CHD) and congenital anomalies of the kidney and urinary tract (CAKUT) account for significant morbidity and mortality in childhood. Dozens of monogenic causes of anomalies in each organ system have been identified. However, even though 30% of CHD patients also have a CAKUT and both organs arise from the lateral mesoderm, there is sparse overlap of the genes implicated in the congenital anomalies for these organ systems. We sought to determine whether patients with both CAKUT and CHD have a monogenic etiology, with the long-term goal of guiding future diagnostic work up and improving outcomes.

Methods

Retrospective review of electronic medical records (EMR), identifying patients admitted to Rady Children's Hospital between January 2015 and July 2020 with both CAKUT and CHD who underwent either whole exome sequencing (WES) or whole genome sequencing (WGS). Data collected included demographics, presenting phenotype, genetic results, and mother's pregnancy history. WGS data was reanalyzed with a specific focus on the CAKUT and CHD phenotype. Genetic results were reviewed to identify causative, candidate, and novel genes for the CAKUT and CHD phenotype. Associated additional structural malformations were identified and categorized.

Results

Thirty-two patients were identified. Eight patients had causative variants for the CAKUT/CHD phenotype, three patients had candidate variants, and three patients had potential novel variants. Five patients had variants in genes not associated with the CAKUT/CHD phenotype, and 13 patients had no variant identified. Of these, eight patients were identified as having possible alternative causes for their CHD/CAKUT phenotype. Eighty-eight percent of all CAKUT/CHD patients had at least one additional organ system with a structural malformation.

Conclusions

Overall, our study demonstrated a high rate of monogenic etiologies in hospitalized patients with both CHD and CAKUT, with a diagnostic rate of 44%. Thus, physicians should have a high suspicion for genetic disease in this population. Together, these data provide valuable information on how to approach acutely ill patients with CAKUT and CHD, including guiding diagnostic work up for associated phenotypes, as well as novel insights into the genetics of CAKUT and CHD overlap syndromes in hospitalized children.

The microbial production, isolation, and structure elucidation of four new napyradiomycin congeners (1-4) is reported. The structures of these compounds, which are new additions to the marine-derived meroterpenoids, were defined by comprehensive spectroscopic analysis and by X-ray crystallography. Using fluorescence-activated cell sorting (FACS) analysis, napyradiomycins 1-4 were observed to induce apoptosis in the colon adenocarcinoma cell line HCT-116, indicating the possibility of a specific biochemical target for this class of cytotoxins.

Pathogenic and likely pathogenic variants in the TECRL gene are known to be associated with recessive catecholaminergic polymorphic ventricular tachycardia 3, which can include prolonged QT intervals (MIM#614021). We report a case of cardiac arrest in a previously healthy adolescent male in the community. The patient was found to have a novel maternally inherited likely pathogenic variant in TECRL (c.915T>G [p.Tyr305Ter]) and an additional 19-kb duplication encompassing multiple exons of TECRL (chr4:65165944-65185287, dup [4q13.1]) not identified in the mother. Genetic results were revealed via rapid whole-genome sequencing, which allowed appropriate treatment and prognostication.