Sex-Based Mechanisms of Cardiac Development and Function: Applications for Induced-Pluripotent Stem Cell Derived-Cardiomyocytes.

Males and females exhibit intrinsic differences in the structure and function of the heart, while the prevalence and severity of cardiovascular disease vary in the two sexes. However, the mechanisms of this sex-based dimorphism are yet to be elucidated. Sex chromosomes and sex hormones are the main contributors to sex-based differences in cardiac physiology and pathophysiology. In recent years, the advances in induced pluripotent stem cell-derived cardiac models and multi-omic approaches have enabled a more comprehensive understanding of the sex-specific differences in the human heart. Here, we provide an overview of the roles of these two factors throughout cardiac development and explore the sex hormone signaling pathways involved. We will also discuss how the employment of stem cell-based cardiac models and single-cell RNA sequencing help us further investigate sex differences in healthy and diseased hearts.

Bioprosthetic Valve Remodeling in Nonfracturable Surgical Valves: Impact on THV Expansion and Hydrodynamic Performance.

BACKGROUND: There are limited data on the effect of bioprosthetic valve remodeling (BVR) on transcatheter heart valve (THV) expansion and function following valve-in-valve (VIV) transcatheter aortic valve replacement (TAVR) in a nonfracturable surgical heart valve (SHV). OBJECTIVES: This study sought to assess the impact of BVR of nonfracturable SHVs on THVs after VIV implantation. METHODS: VIV TAVR was performed using 23-mm SAPIEN3 (S3, Edwards Lifesciences) or 23/26-mm Evolut Pro (Medtronic) THVs implanted in 21/23-mm Trifecta (Abbott Structural Heart) and 21/23-mm Hancock (Medtronic) SHVs with BVR performed with a noncompliant TRUE balloon (Bard Peripheral Vascular Inc). Hydrodynamic assessment was performed, and multimodality imaging including micro-computed tomography was performed before and after BVR to assess THV and SHV expansion. RESULTS: BVR resulted in limited improvement of THV expansion. The largest gain in expansion was observed for the S3 in the 21-mm Trifecta with up to a 12.7% increase in expansion at the outflow of the valve. Minimal change was observed at the level of the sewing ring. The Hancock was less amenable to BVR with lower final expansion dimensions than the Trifecta. BVR also resulted in notable surgical post flaring of up to 17.6°, which was generally more marked with the S3 than with the Evolut Pro. Finally, BVR resulted in very limited improvement in hydrodynamic function. Severe pinwheeling was observed with the S3, which improved slightly but persisted despite BVR. CONCLUSIONS: When performing VIV TAVR inside a Trifecta and Hancock SHV, BVR had a limited impact on THV expansion and resulted in SHV post flaring with unknown consequences on coronary obstruction risk and long-term THV function.

Collection of patient race, ethnicity, and language data in emergency departments: a national survey.

PURPOSE: There is mounting evidence of racial and ethnic discrimination in the Canadian health care system. Patient level race and ethnicity data are required to identify potential disparities in clinical outcomes and access to health care. However, it is not known what patient race, ethnicity, and language data are collected by Canadian hospitals. This gap limits opportunities to identify and address inequalities in the health care system. The emergency department (ED) is a major point of contact for many patients accessing the health care system, and is therefore a reasonable place to conduct analysis of patient data collection. This study aims to quantify the proportion of Canadian EDs that collect patient race, ethnicity, and primary language data. METHODS: We identified all Canadian EDs and distributed a survey to 616 EDs across the country. RESULTS: We received responses representing 202 EDs (32.8%). One fifth (20.3%) of responding EDs reported that they collected race and ethnicity data and 38.1% collected primary language data. Reported uses for these data included quality improvement, research, and direct patient care. CONCLUSION: The majority of Canadian EDs do not collect patient race, ethnicity, and language data. This gap limits our ability to identify inequalities in health outcomes or access to health care. Lack of race, ethnicity, and language data also hinders our ability to develop and evaluate programs and interventions that aim to correct these inequalities.

RéSUMé: OBJECTIF: Il existe de plus en plus de preuves de discrimination raciale et ethnique dans le système de soins de santé canadien. Les données relatives à la race et à l'ethnicité des patients sont nécessaires pour identifier les disparités potentielles dans les résultats cliniques et l'accès aux soins de santé. Cependant, on ne sait pas quelles données sur la race, l'ethnicité et la langue des patients sont recueillies par les hôpitaux canadiens. Cette lacune limite les possibilités d'identifier et de traiter les inégalités dans le système de soins de santé. Le service des urgences (SU) est un point de contact majeur pour de nombreux patients accédant au système de soins de santé, et constitue donc un endroit raisonnable pour mener une analyse de la collecte de données sur les patients. Cette étude vise à quantifier la proportion de services d'urgence canadiens qui recueillent des données sur la race, l'origine ethnique et la langue principale des patients. MéTHODES: Nous avons recensé tous les services d'urgence canadiens et distribué un sondage à 616 services d'urgence dans tout le pays. RéSULTATS: Les réponses reçues représentent 202 services d'urgence (32,8 %). Un cinquième (20,3 %) des services d'urgence qui ont répondu ont indiqué qu'ils recueillaient des données sur la race et l'origine ethnique, et 38,1 %, sur la langue principale. Les utilisations déclarées de ces données comprenaient l'amélioration de la qualité, la recherche et les soins directs aux patients. CONCLUSION: La majorité des services d'urgence canadiens ne recueillent pas de données sur la race, l'origine ethnique et la langue des patients. Cet écart limite notre capacité à identifier les inégalités dans les résultats de santé ou l'accès aux soins de santé. Le manque de données sur la race, l'ethnicité et la langue entrave également notre capacité à élaborer et à évaluer les programmes et les interventions visant à corriger ces inégalités.

AKI in COVID-19-Associated Multisystem Inflammatory Syndrome in Children (MIS-C).

Background: Multisystem inflammatory syndrome in children (MIS-C) is a recently identified entity in association with COVID-19. AKI has been widely reported in patients with primary COVID-19 infection. However, there is a paucity of literature regarding renal injury in MIS-C. We aim to characterize AKI in MIS-C in this cohort identified at a major children's hospital in New York City during the COVID-19 pandemic. Methods: We conducted a retrospective cohort study of children 0-20 years old admitted to Morgan Stanley Children's Hospital (MSCH) between April 18th and September 23rd, 2020. Patients were included if they met criteria for MIS-C on the basis of CDC guidelines. All patients were evaluated for the presence of AKI, and AKI was staged according to KDIGO criteria. Results: Of the 57 children who met inclusion criteria, 46% (26 of 57) were found to have AKI. The majority of patients (58%; 15 of 26) were classified as KDIGO stage 1. AKI was present upon admission in 70% of those identified. All patients had resolution of AKI at discharge, with 61% achieving recovery by day 2. One patient required dialysis. When compared with those without renal injury, the AKI cohort was older (P<0.001) and had higher median peak values of CRP (P<0.001), IL-6 (P=0.02), ferritin (P<0.001), and procalcitonin (P=0.02). More patients with AKI had left ventricular systolic dysfunction (P<0.001) and lymphopenia (P=0.01) when compared with those without AKI. No differences in body mass index or sex were found. Conclusions: Although children with MIS-C may develop AKI, our study suggests that most experience mild disease, swift resolution, and promising outcome. Older age, increased inflammation, and left ventricular systolic dysfunction may be risk factors. Our study highlights the substantial differences in epidemiology and outcomes between AKI associated with pediatric MIS-C versus primary COVID-19 infection.

COVID-19-Related Internet Search Patterns Among People in the United States: Exploratory Analysis.

BACKGROUND: The internet is a well-known source of information that patients use to better inform their opinions and to guide their conversations with physicians during clinic visits. The novelty of the recent COVID-19 outbreak has led patients to turn more frequently to the internet to gather more information and to alleviate their concerns about the virus. OBJECTIVE: The aims of the study were to (1) determine the most commonly searched phrases related to COVID-19 in the United States and (2) identify the sources of information for these web searches. METHODS: Search terms related to COVID-19 were entered into Google. Questions and websites from Google web search were extracted to a database using customized software. Each question was categorized into one of 6 topics: clinical signs and symptoms, treatment, transmission, cleaning methods, activity modification, and policy. Additionally, the websites were categorized according to source: World Health Organization (WHO), Centers for Disease Control and Prevention (CDC), non-CDC government, academic, news, and other media. RESULTS: In total, 200 questions and websites were extracted. The most common question topic was transmission (n=63, 31.5%), followed by clinical signs and symptoms (n=54, 27.0%) and activity modification (n=31, 15.5%). Notably, the clinical signs and symptoms category captured questions about myths associated with the disease, such as whether consuming alcohol stops the coronavirus. The most common websites provided were maintained by the CDC, the WHO, and academic medical organizations. Collectively, these three sources accounted for 84.0% (n=168) of the websites in our sample. CONCLUSIONS: In the United States, the most commonly searched topics related to COVID-19 were transmission, clinical signs and symptoms, and activity modification. Reassuringly, a sizable majority of internet sources provided were from major health organizations or from academic medical institutions.

Genetic Factors Contribute to Risk for Neonatal Respiratory Distress Syndrome among Moderately Preterm, Late Preterm, and Term Infants.

OBJECTIVE: To determine the genetic contribution to risk for respiratory distress syndrome (RDS) among moderately preterm, late preterm, and term infants (estimated gestational age ≥32 weeks) of African- and European-descent. STUDY DESIGN: We reviewed clinical records for 524 consecutive twin pairs ≥32 weeks gestation. We identified pairs in which at least 1 twin had RDS (n = 225) and compared the concordance of RDS between monozygotic and dizygotic twins. Using mixed-effects logistic regression, we identified covariates that increased disease risk. We performed additive genetic, common environmental, and residual effects modeling to estimate genetic variance and used the ratio of genetic variance to total variance to estimate genetic contribution to RDS disease risk. RESULTS: Monozygotic twins were more concordant for RDS than dizygotic twins (P = .0040). Estimated gestational age, European-descent, male sex, delivery by cesarean, and 5-minute Apgar score each independently increased risk for RDS. After adjusting for these covariates, genetic effects accounted for 58% (P = .0002) of the RDS disease risk variance for all twin pairs. CONCLUSIONS: In addition to environmental factors, genetic factors may contribute to RDS risk among moderately preterm, late preterm, and term infants. Discovery of risk alleles may be important for prediction and management of RDS risk.

Structural basis of DNA gyrase inhibition by antibacterial QPT-1, anticancer drug etoposide and moxifloxacin.

New antibacterials are needed to tackle antibiotic-resistant bacteria. Type IIA topoisomerases (topo2As), the targets of fluoroquinolones, regulate DNA topology by creating transient double-strand DNA breaks. Here we report the first co-crystal structures of the antibacterial QPT-1 and the anticancer drug etoposide with Staphylococcus aureus DNA gyrase, showing binding at the same sites in the cleaved DNA as the fluoroquinolone moxifloxacin. Unlike moxifloxacin, QPT-1 and etoposide interact with conserved GyrB TOPRIM residues rationalizing why QPT-1 can overcome fluoroquinolone resistance. Our data show etoposide's antibacterial activity is due to DNA gyrase inhibition and suggests other anticancer agents act similarly. Analysis of multiple DNA gyrase co-crystal structures, including asymmetric cleavage complexes, led to a 'pair of swing-doors' hypothesis in which the movement of one DNA segment regulates cleavage and religation of the second DNA duplex. This mechanism can explain QPT-1's bacterial specificity. Structure-based strategies for developing topo2A antibacterials are suggested.

The long tail and rare disease research: the impact of next-generation sequencing for rare Mendelian disorders.

There are an estimated 6000-8000 rare Mendelian diseases that collectively affect 30 million individuals in the United States. The low incidence and prevalence of these diseases present significant challenges to improving diagnostics and treatments. Next-generation sequencing (NGS) technologies have revolutionized research of rare diseases. This article will first comment on the effectiveness of NGS through the lens of long-tailed economics. We then provide an overview of recent developments and challenges of NGS-based research on rare diseases. As the quality of NGS studies improve and the cost of sequencing decreases, NGS will continue to make a significant impact on the study of rare diseases moving forward.

Type IIA topoisomerase inhibition by a new class of antibacterial agents.

Despite the success of genomics in identifying new essential bacterial genes, there is a lack of sustainable leads in antibacterial drug discovery to address increasing multidrug resistance. Type IIA topoisomerases cleave and religate DNA to regulate DNA topology and are a major class of antibacterial and anticancer drug targets, yet there is no well developed structural basis for understanding drug action. Here we report the 2.1 A crystal structure of a potent, new class, broad-spectrum antibacterial agent in complex with Staphylococcus aureus DNA gyrase and DNA, showing a new mode of inhibition that circumvents fluoroquinolone resistance in this clinically important drug target. The inhibitor 'bridges' the DNA and a transient non-catalytic pocket on the two-fold axis at the GyrA dimer interface, and is close to the active sites and fluoroquinolone binding sites. In the inhibitor complex the active site seems poised to cleave the DNA, with a single metal ion observed between the TOPRIM (topoisomerase/primase) domain and the scissile phosphate. This work provides new insights into the mechanism of topoisomerase action and a platform for structure-based drug design of a new class of antibacterial agents against a clinically proven, but conformationally flexible, enzyme class.

ERK activation drives intestinal tumorigenesis in Apc(min/+) mice.

Toll-like receptor (TLR) signaling is essential for intestinal tumorigenesis in Apc(min/+) mice, but the mechanisms by which Apc enhances tumor growth are unknown. Here we show that microflora-MyD88-ERK signaling in intestinal epithelial cells (IECs) promotes tumorigenesis by increasing the stability of the c-Myc oncoprotein. Activation of ERK (extracellular signal-related kinase) phosphorylates c-Myc, preventing its ubiquitination and subsequent proteasomal degradation. Accordingly, Apc(min/+)/Myd88(-/-) mice have lower phospho-ERK (p-ERK) levels and fewer and smaller IEC tumors than Apc(min/+) mice. MyD88 (myeloid differentiation primary response gene 88)-independent activation of ERK by epidermal growth factor (EGF) increased p-ERK and c-Myc and restored the multiple intestinal neoplasia (Min) phenotype in Apc(min/+)/Myd88(-/-) mice. Administration of an ERK inhibitor suppressed intestinal tumorigenesis in EGF-treated Apc(min/+)/Myd88(-/-) and Apc(min/+) mice and increased their survival. Our data reveal a new facet of oncogene-environment interaction, in which microflora-induced TLR activation regulates oncogene expression and related IEC tumor growth in a susceptible host.

Conventional dendritic cells regulate the outcome of colonic inflammation independently of T cells.

We explored the physiological role of conventional dendritic cells (cDCs) in acute colitis induced by a single cycle of dextran sodium sulfate administration. Depending on their mode of activation and independently of T cells, cDCs can enhance or attenuate the severity of dextran sodium sulfate-induced colitis. The latter beneficial effect was achieved, in part, by IFN-1 induced by Toll-like receptor 9-activated cDCs. IFN-1 inhibits colonic inflammation by regulating neutrophil and monocyte trafficking to the inflamed colon and restraining the inflammatory products of tissue macrophages. These data highlight a novel role of cDCs in the regulation of other innate immune cells and position them as major players in acute colonic inflammation.

Toll-like receptor signaling in intestinal epithelial cells contributes to colonic homoeostasis.

PURPOSE OF REVIEW: Since intestinal epithelium expresses Toll-like receptors, it was suggested that the intestinal epithelium is actively involved in the maintenance of colonic homeostasis. Here we describe our recent findings, which support an active contribution of colonic epithelium to intestinal homeostasis via a unique activation of epithelial TLR9. RECENT FINDINGS: Recent data indicate that stimulation of Toll-like receptors by intestinal microbiota supports colonic homeostasis. Several Toll-like receptors are expressed in intestinal epithelium. TLR9, an intracellular protein in immune cells, is expressed on the cell surfaces of intestinal epithelium, both on the apical and the basolateral membrane. TLR9 signaling varies in a domain-specific manner; whereas JNK is activated by TLR9 ligand both apically or basolaterally, NF-kappaB is activated only via basolateral stimulation. In apical TLR9 stimulation, IkappaB is phosphorylated and ubiquitinated but is not degraded, and NF-kappaB-dependent inflammatory signals are not transduced. Stimulation of apical TLR9 compromises the inflammatory cascade induced basolaterally by several other Toll-like receptor ligands, suggesting that apical exposure to luminal microbial DNA restrains intestinal inflammation. SUMMARY: These data indicate that certain luminal bacterial products support colonic homeostasis via activation of epithelial Toll-like receptors. The role of epithelial Toll-like receptor expression and activation in the pathogenesis of human inflammatory bowel disease is yet to be explored.

Maintenance of colonic homeostasis by distinctive apical TLR9 signalling in intestinal epithelial cells.

The mechanisms by which commensal bacteria suppress inflammatory signalling in the gut are still unclear. Here, we present a cellular mechanism whereby the polarity of intestinal epithelial cells (IECs) has a major role in colonic homeostasis. TLR9 activation through apical and basolateral surface domains have distinct transcriptional responses, evident by NF-kappaB activation and cDNA microarray analysis. Whereas basolateral TLR9 signals IkappaBalpha degradation and activation of the NF-kappaB pathway, apical TLR9 stimulation invokes a unique response in which ubiquitinated IkappaB accumulates in the cytoplasm preventing NF-kappaB activation. Furthermore, apical TLR9 stimulation confers intracellular tolerance to subsequent TLR challenges. IECs in TLR9-deficient mice, when compared with wild-type and TLR2-deficient mice, display a lower NF-kappaB activation threshold and these mice are highly susceptible to experimental colitis. Our data provide a case for organ-specific innate immunity in which TLR expression in polarized IECs has uniquely evolved to maintain colonic homeostasis and regulate tolerance and inflammation.

Activation of anti-hepatitis C virus responses via Toll-like receptor 7.

IFN-alpha is used to suppress the replication of hepatitis C virus (HCV) in chronically infected patients with partial success. Here we present evidence showing that a ligand of Toll-like receptor 7 (TLR7) can induce anti-HCV immunity not only by IFN induction, but also through an IFN-independent mechanism. Human hepatocyte line Huh-7 carrying an HCV replicon expressed TLR7, and activation of the receptor induced several antiviral genes including IFN regulatory factor-7. Inhibitors of the enzyme inosine monophosphate dehydrogenase augmented both IFN-dependent and -independent antiviral effect. Prolonged exposure of Huh-7 cells to a TLR7 ligand [SM360320 (9-benzyl-8-hydroxy-2-(2-methoxyethoxy)adenine)], alone or in combination with an inosine monophosphate dehydrogenase inhibitor, reduced HCV levels dose dependently. Immunohistochemical analysis of livers shows that TLR7 is expressed in hepatocytes of normal or HCV-infected people. Because TLR7 agonists can impede HCV infection both via type I IFN and independently of IFN, they may be considered as an alternative treatment of chronic HCV infection, especially in IFN-alpha-resistant patients.

Induction and inhibition of the Th2 phenotype spread: implications for childhood asthma.

The interactions between genetic and environmental factors play a major role in the development of childhood asthma. We hypothesized that a pre-existing Th2/asthmatic response can promote Th2 responses to newly encountered Ags (i.e., phenotype spread). To test this hypothesis, we developed a mouse model in which the requirements for the induction and inhibition of phenotype spread to a clinically relevant neo-allergen (i.e., ragweed) were investigated. Our results indicate that 1) phenotype spread to the neo-allergen can be induced only within the first 8 h after a bronchial challenge with the first Ag (OVA); 2) Th2 differentiation of naive CD4(+) T cells occurs in bronchial lymph nodes; 3) trafficking of naive CD4(+) T cells to local lymph nodes and IL-4 produced by OVA-activated Th2 cells play essential roles in the differentiation of naive CD4(+) T cells to Th2 cells; and 4) suppression of the production of chemokines involved in the homing of naive CD4(+) T and Th2 cells to bronchial lymph nodes by a TLR9 agonist inhibited phenotype spread and abrogated the consequent development of experimental asthma. These findings provide a mechanistic insight into Th2 phenotype spread and offer an animal model for testing relevant immunomodulatory interventions.