Publications by authors named "Stapleton D"

Introduction: Early detection of neurodegeneration is essential for optimizing interventions. The highly reproducible progression of neurodegeneration in the decrepit () mouse allows investigation of early biomarkers and mechanisms of brain injury.

Methods: Using high-frequency ultrasound, the common carotid arteries of female and male and control mice were imaged longitudinally at time points bracketing the disease progression (50, 75, and 125 days of age) ( = 6 mice/group/sex).

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Objectives: This study aimed to identify enablers and barriers to participation in MRI for clinical indications and scientific research, and to determine the perceptions of MRI performed during pregnancy.

Methods: We conducted a survey of 156 pregnant people in Newfoundland and Labrador including sociodemographic information, obstetrical history, MRI history, and willingness to participate in an MRI. Categorical variables were analyzed using a Fisher exact test and open-ended questions were analyzed using thematic analysis.

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Diabetic nephropathy (DN) is the leading cause of end-stage renal disease in the U.S. and has a significant impact on human suffering.

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Introduction: Our understanding of the etiology of preterm birth (PTB) is incomplete; however, recent evidence has found a strong association between placental dysfunction and PTB. Altered placental metabolism may precede placental dysfunction and therefore the study of placental metabolic profiles could identify early biomarkers of PTB. In this study, we evaluated the placental metabolome in PTB in intact tissue samples using nuclear magnetic resonance (NMR) and spectral editing.

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Insufficient insulin secretion to meet metabolic demand results in diabetes. The intracellular flux of Ca into β-cells triggers insulin release. Since genetics strongly influences variation in islet secretory responses, we surveyed islet Ca dynamics in eight genetically diverse mouse strains.

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G6PC2 is predominantly expressed in pancreatic islet β-cells where it encodes a glucose-6-phosphatase catalytic subunit that modulates the sensitivity of insulin secretion to glucose by opposing the action of glucokinase, thereby regulating fasting blood glucose (FBG). Prior studies have shown that the G6pc2 promoter alone is unable to confer sustained islet-specific gene expression in mice, suggesting the existence of distal enhancers that regulate G6pc2 expression. Using information from both mice and humans and knowledge that single nucleotide polymorphisms (SNPs) both within and near G6PC2 are associated with variations in FBG in humans, we identified several putative enhancers 3' of G6pc2.

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We and others have previously shown that genetic association can be used to make causal connections between gene loci and small molecules measured by mass spectrometry in the bloodstream and in tissues. We identified a locus on mouse chromosome 7 where several phospholipids in liver showed strong genetic association to distinct gene loci. In this study, we integrated gene expression data with genetic association data to identify a single gene at the chromosome 7 locus as the driver of the phospholipid phenotypes.

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We and others have previously shown that genetic association can be used to make causal connections between gene loci and small molecules measured by mass spectrometry in the bloodstream and in tissues. We identified a locus on mouse chromosome 7 where several phospholipids in liver showed strong genetic association to distinct gene loci. In this study, we integrated gene expression data with genetic association data to identify a single gene at the chromosome 7 locus as the driver of the phospholipid phenotypes.

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Objective: To examine the relationship between umbilical cord insertion site, placental pathology and adverse pregnancy outcome in a cohort of normal and complicated pregnancies.

Methods: Sonographic measurement of the cord insertion and detailed placental pathology were performed in 309 participants. Associations between cord insertion site, placental pathology and adverse pregnancy outcome (pre-eclampsia, preterm birth, small-for-gestational age) were examined.

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The molecular bases of how host genetic variation impacts the gut microbiome remain largely unknown. Here we used a genetically diverse mouse population and applied systems genetics strategies to identify interactions between host and microbe phenotypes including microbial functions, using faecal metagenomics, small intestinal transcripts and caecal lipids that influence microbe-host dynamics. Quantitative trait locus (QTL) mapping identified murine genomic regions associated with variations in bacterial taxa; bacterial functions including motility, sporulation and lipopolysaccharide production and levels of bacterial- and host-derived lipids.

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Introduction: Endothelial nitric oxide synthase (eNOS) produces nitric oxide, which is essential for a variety of physiological functions in the brain. Previous work has demonstrated the detrimental effects of eNOS deficiency on brain function in male eNOS knockout (eNOS KO) mice. However, the effect of eNOS deficiency on brain structure and any association between these effects and sex is unknown.

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Context: Assessment of running mechanics has traditionally been conducted in laboratory settings; the advancement of wearable technology permits data collection during outdoor training sessions. Exploring changes in running mechanics across training-session types may assist runners, coaches, and sports medicine clinicians in improving performance and managing the injury risk.

Objective: To examine changes in running mechanics on the basis of routine training-session types.

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Insulin secretion from pancreatic β cells is essential for glucose homeostasis. An insufficient response to the demand for insulin results in diabetes. We previously showed that β cell-specific deletion of Zfp148 (β-Zfp148KO) improves glucose tolerance and insulin secretion in mice.

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Bin/amphiphysin/Rvs (BAR) domains are positively charged crescent-shaped modules that mediate curvature of negatively charged lipid membranes during remodeling processes. The BAR domain proteins PICK1, ICA69, and the arfaptins have recently been demonstrated to coordinate the budding and formation of immature secretory granules (ISGs) at the trans-Golgi network. Here, we identify 4 coding variants in the PICK1 gene from a whole-exome screening of Danish patients with diabetes that each involve a change in positively charged residues in the PICK1 BAR domain.

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Background And Aims: Barrett's esophagus (BE) is the precursor to esophageal adenocarcinoma. A major challenge is identifying the small group with BE who will progress to advanced disease from the many who will not. Assessment of p53 status has promise as a predictive biomarker, but analytic limitations and lack of validation have precluded its use.

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To fully exploit the benefits of additive manufacturing (AM), an understanding of its processing, microstructural, and mechanical aspects, and their interdependent characteristics, is necessary. In certain instances, AM materials may be desired for applications where impact toughness is a key property, such as in gas turbine fan blades, where foreign or direct object damage may occur. In this research, the impact energy of a series of Ti-6Al-4V specimens produced via electron beam powder bed fusion (EBPBF) was established via Charpy impact testing.

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The transcription factor NFATC2 induces β cell proliferation in mouse and human islets. However, the genomic targets that mediate these effects have not been identified. We expressed active forms of Nfatc2 and Nfatc1 in human islets.

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Genome-wide association studies reveal many non-coding variants associated with complex traits. However, model organism studies largely remain as an untapped resource for unveiling the effector genes of non-coding variants. We develop INFIMA, Integrative Fine-Mapping, to pinpoint causal SNPs for diversity outbred (DO) mice eQTL by integrating founder mice multi-omics data including ATAC-seq, RNA-seq, footprinting, and in silico mutation analysis.

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We used two-dimensional IR bioimaging to study the structural heterogeneity of formalin-fixed mouse pancreas. Images were generated from the hyperspectral data sets by plotting quantities associated with the amide I vibrational mode, which is created by the backbone carbonyl stretch. Images that measure the fundamental vibrational frequencies, cross peaks, and anharmonic shifts are presented.

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Background: Dance requires integration and synergy between movement, postural stability, and body alignment to effectively execute the technical and aesthetic requirements of the performance. Evaluation of movement competency and dynamic balance provides opportunity to identify dysfunctional movement which may negatively impact both artistic and technical aspects of dance performance. Investigation of the relationships between movement competency and postural control may aid in technical development, performance improvement, and ultimately injury reduction.

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Despite the crucial roles of lipids in metabolism, we are still at the early stages of comprehensively annotating lipid species and their genetic basis. Mass spectrometry-based discovery lipidomics offers the potential to globally survey lipids and their relative abundances in various biological samples. To discover the genetics of lipid features obtained through high-resolution liquid chromatography-tandem mass spectrometry, we analysed liver and plasma from 384 diversity outbred mice, and quantified 3,283 molecular features.

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Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a recently validated therapeutic target for lowering low-density lipoprotein cholesterol (LDL-C). Through phenotypic screening, we previously discovered a class of small-molecules with a 2,3'-diindolymethane (DIM) skeleton that can decrease the expression of PCSK9. But these compounds have low potency and low metabolically stability.

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Stapleton, DT, Boergers, RJ, Rodriguez, J, Green, G, Johnson, K, Williams, P, Leelum, N, Jackson, L, and Vallorosi, J. The relationship between functional movement, dynamic stability, and athletic performance assessments in baseball and softball athletes. J Strength Cond Res 35(12S): S42-S50, 2021-Despite recent popularity, the relationship between movement quality and measures of athletic performance remains inconclusive.

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The incidence of metabolic syndrome continues to rise globally. In mice, intravenous administration of interleukin-22 (IL-22) ameliorates various disease phenotypes associated with diet-induced metabolic syndrome. In patients, oral treatment is favored over intravenous treatment, but methodologies to deliver IL-22 via the oral route are nonexistent.

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