Publications by authors named "Michael Yeager"

Objectives: We tested the hypothesis that aberrant expression of Hsa21-encoded interferon genes in peripheral blood immune cells would correlate to immune cell dysfunction in children with Down syndrome (DS).

Study Design: We performed flow cytometry to quantify peripheral blood leukocyte subtypes and measured their ability to migrate and phagocytose. In matched samples, we measured gene expression levels for constituents of interferon signaling pathways.

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Objectives: We sought to investigate whether the Dp16 mouse model of Down syndrome (DS) is more susceptible to severe and lethal respiratory tract infection by .

Study Design: We infected controls and Dp16 mice with and measured survival rates. We compared cytokine production by primary lung cell cultures exposed to .

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Article Synopsis
  • The study investigated the lung and heart biology of the Dp16 mouse model of Down syndrome to understand its susceptibility to respiratory infections.
  • Researchers compared blood samples, gene and protein expressions, and performed unique pulmonary and cardiac function tests on Dp16 mice versus controls.
  • Findings indicated that Dp16 mice exhibit distinct cytokines, altered gene and protein expressions, increased lung stiffness, and hypotonic heart ventricles, suggesting they are a valuable model for studying respiratory infections associated with Down syndrome.
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Inhomogeneous in-plane deformation of soft materials or cutting and folding of inextensible flat sheets enables shape-morphing from two dimensional (2D) to three-dimensional (3D), while the resulting structures often have weakened mechanical strength. Shells like nacre are known for the superior fracture toughness due to the "brick and mortar" composite layers, enabling stress redistribution and crack stopping. Here, we report an optimal and universal cutting and stacking strategy that transforms composite plies into 3D doubly curved shapes with nacre-like architectures.

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Disturbed balance between matrix metalloproteinases (MMPs) and their respective tissue inhibitors (TIMPs) is a well-recognized pathophysiological component of pulmonary arterial hypertension (PAH). Both classes of proteinases have been associated with clinical outcomes as well as with specific pathological features of ventricular dysfunction and pulmonary arterial remodeling. The purpose of this study was to evaluate the circulating levels of MMPs and TIMPs in children with PAH undergoing the same-day cardiac magnetic resonance imaging (MRI) and right heart catheterization.

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People with Down syndrome (DS; trisomy 21) display a different disease spectrum relative to the general population, including lower rates of solid malignancies and higher incidence of neurological and autoimmune conditions. However, the mechanisms driving this unique clinical profile await elucidation. We completed a deep mapping of the immune system in adults with DS using mass cytometry to evaluate 100 immune cell types, which revealed global immune dysregulation consistent with chronic inflammation, including key changes in the myeloid and lymphoid cell compartments.

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Background: Qualitative and quantitative flow hemodynamic indexes have been shown to reflect right ventricular (RV) afterload and function in pulmonary hypertension (PH). We aimed to quantify flow hemodynamic formations in pulmonary arteries using 4-dimensional flow cardiac magnetic resonance imaging and the spatial velocity derivatives helicity and vorticity in a heterogeneous PH population.

Methods And Results: Patients with PH (n=35) and controls (n=10) underwent 4-dimensional flow magnetic resonance imaging study for computation of helicity and vorticity in the main pulmonary artery (MPA), the right pulmonary artery, and the RV outflow tract.

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Trisomy 21 (Down Syndrome, DS) is the most common chromosomal anomaly. Although DS is mostly perceived as affecting cognitive abilities and cardiac health, individuals with DS also exhibit dysregulated immune functions. Levels of pro-inflammatory cytokines are increased, but intrinsic alterations of innate immunity are understudied in DS.

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Down syndrome is the most common chromosomal abnormality among live-born infants. Through full or partial trisomy of chromosome 21, Down syndrome is associated with cognitive impairment, congenital malformations (particularly cardiovascular) and dysmorphic features. Immune disturbances in Down syndrome account for an enormous disease burden ranging from quality-of-life issues (autoimmune alopecia) to more serious health issues (autoimmune thyroiditis) and life-threatening issues (leukaemia, respiratory tract infections and pulmonary hypertension).

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Pediatric lung diseases remain a costly worldwide health burden. For many children with end-stage lung disease, lung transplantation remains the only therapeutic option. Due to the limited number of lungs available for transplantation, alternatives to lung transplant are desperately needed.

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Pediatric pulmonary arterial hypertension (PAH) is an uncommon disease that can occur in neonates, infants, and children, and is associated with high morbidity and mortality. Despite advances in treatment strategies over the last two decades, the underlying structural and functional changes to the pulmonary arterial circulation are progressive and lead eventually to right heart failure. The management of PAH in children is complex due not only to the developmental aspects but also because most evidence-based practices derive from adult PAH studies.

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Recently a great deal of progress has been made in our understanding of pulmonary hypertension (PH). Research from the past 30 years has resulted in newer treatments that provide symptomatic improvements and delayed disease progression. Unfortunately, the cure for patients with this lethal syndrome remains stubbornly elusive.

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Pulmonary hypertension (PH) is a fatal syndrome that arises from a multifactorial and complex background, is characterized by increased pulmonary vascular resistance and right heart afterload, and often leads to cor pulmonale. Over the past decades, remarkable progress has been made in reducing patient symptoms and delaying the progression of the disease. Unfortunately, PH remains a disease with no cure.

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Therapeutic approaches in pediatric pulmonary arterial hypertension (PAH) are based primarily on clinician experience, in contrast to the evidence-based approach in adults with pulmonary hypertension. There is a clear and present need for non-invasive and objective biomarkers to guide the accurate diagnosis, treatment, and prognosis of this disease in children. The multifaceted spectrum of disease, clinical presentation, and association with other diseases makes this a formidable challenge.

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Fibrosis, which is defined as excessive accumulation of fibrous connective tissue, contributes to the pathogenesis of numerous diseases involving diverse organ systems. Cardiac fibrosis predisposes individuals to myocardial ischemia, arrhythmias and sudden death, and is commonly associated with diastolic dysfunction. Histone deacetylase (HDAC) inhibitors block cardiac fibrosis in pre-clinical models of heart failure.

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Rationale: Pulmonary hypertensive remodeling is characterized by excessive proliferation, migration, and proinflammatory activation of adventitial fibroblasts. In culture, fibroblasts maintain a similar activated phenotype. The mechanisms responsible for generation/maintenance of this phenotype remain unknown.

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Rationale: Autoimmunity has long been associated with pulmonary hypertension. Bronchus-associated lymphoid tissue plays important roles in antigen sampling and self-tolerance during infection and inflammation.

Objectives: We reasoned that activated bronchus-associated lymphoid tissue would be evident in rats with pulmonary hypertension, and that loss of self-tolerance would result in production of pathologic autoantibodies that drive vascular remodeling.

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Aims: Pulmonary hypertension (PH) is characterized by an oxidant/antioxidant imbalance that promotes abnormal vascular responses. Reactive oxygen species, such as superoxide (O(2)(•-)), contribute to the pathogenesis of PH and vascular responses, including vascular remodeling and inflammation. This study sought to investigate the protective role of a pharmacological catalytic antioxidant, a superoxide dismutase (SOD) mimetic (MnTE-2-PyP), in hypoxia-induced PH, vascular remodeling, and NALP3 (NACHT, LRR, and PYD domain-containing protein 3)-mediated inflammation.

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The vascular adventitia acts as a biological processing center for the retrieval, integration, storage, and release of key regulators of vessel wall function. It is the most complex compartment of the vessel wall and is composed of a variety of cells, including fibroblasts, immunomodulatory cells (dendritic cells and macrophages), progenitor cells, vasa vasorum endothelial cells and pericytes, and adrenergic nerves. In response to vascular stress or injury, resident adventitial cells are often the first to be activated and reprogrammed to influence the tone and structure of the vessel wall; to initiate and perpetuate chronic vascular inflammation; and to stimulate expansion of the vasa vasorum, which can act as a conduit for continued inflammatory and progenitor cell delivery to the vessel wall.

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Pulmonary hypertension remains an important cause of morbidity and mortality. Although there is currently no cure, descriptions of defective intracellular trafficking and protein misfolding in vascular cell models of pulmonary hypertension have been recently reported. We tested the hypothesis that activation of the unfolded protein response (UPR) would be associated with the development of severe PH.

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Purpose: The prognosis for children with IPAH unresponsive to therapy is poor. We investigated the plasma proteome for a molecular basis of good versus poor outcome to long-term vasodilator therapy.

Experimental Design: Plasma was collected at baseline or shortly after therapy initiation and following chronic vasodilator therapy, then divided into those with good outcome (n = 8), and those with a poor outcome (n = 7).

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Experimental data indicate that the adventitial compartment of blood vessels, in both the pulmonary and systemic circulations, like the connective tissue stroma in tissues throughout the body, is a critical regulator of vessel wall function in health and disease. It is clear that adventitial cells, and in particular the adventitial fibroblast, are activated early following vascular injury, and play essential roles in regulating vascular wall structure and function through production of chemokines, cytokines, growth factors, and reactive oxygen species (ROS). The recognition of the ability of these cells to generate and maintain inflammatory responses within the vessel wall provides insight into why vascular inflammatory responses, in certain situations, fail to resolve.

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Rationale: Histone deacetylase (HDAC) inhibitors are efficacious in models of hypertension-induced left ventricular heart failure. The consequences of HDAC inhibition in the context of pulmonary hypertension with associated right ventricular cardiac remodeling are poorly understood.

Objective: This study was performed to assess the utility of selective small-molecule inhibitors of class I HDACs in a preclinical model of pulmonary hypertension.

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Pulmonary hypertension is characterized by cellular and structural changes in the walls of pulmonary arteries. Intimal thickening and fibrosis, medial hypertrophy and fibroproliferative changes in the adventitia are commonly observed, as is the extension of smooth muscle into the previously non-muscularized vessels. A majority of these changes are associated with the enhanced presence of α-SM-actin+ cells and inflammatory cells.

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