Publications by authors named "Andrew W Norris"

Background: Immediately after birth, adaptation to the extrauterine environment includes an upregulation of fatty acid catabolism. Cystic fibrosis and untreated hypothyroidism exert a life-long impact on fatty acid metabolism, but their influence during this transitional period is unknown. Children and adults with cystic fibrosis exhibit unbalanced fatty acid composition, most prominently a relative deficit of linoleic acid.

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Inflammation, acinar atrophy, and ductal hyperplasia drive pancreatic remodeling in newborn cystic fibrosis (CF) ferrets lacking a functional cystic fibrosis conductance regulator (CFTR) channel. These changes are associated with a transient phase of glucose intolerance that involves islet destruction and subsequent regeneration near hyperplastic ducts. The phenotypic changes in CF ductal epithelium and their impact on islet function are unknown.

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Introduction: The cause of increased diabetes mellitus (DM) risk in individuals with Turner syndrome (TS) is poorly understood. Parent-of-origin effects related to whether the maternal or paternal X chromosome (Xchr) remains intact have been found for several TS phenotypes, including hypercholesterolemia. Therefore, Xchr parent-of-origin may impact DM risk in TS.

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The lysosome integrates anabolic signalling and nutrient-sensing to regulate intracellular growth pathways. The leucine-rich repeat containing 8 (LRRC8) channel complex forms a lysosomal anion channel and regulates PI3K-AKT-mTOR signalling, skeletal muscle differentiation, growth, and systemic glucose metabolism. Here, we define the endogenous LRRC8 subunits localized to a subset of lysosomes in differentiated myotubes.

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Obesity alters levels of pituitary hormones that govern hepatic immune-metabolic homeostasis, dysregulation of which leads to nonalcoholic fatty liver disease (NAFLD). However, the impact of obesity on intra-pituitary homeostasis is largely unknown. Here, we uncovered a blunted unfolded protein response (UPR) but elevated inflammatory signatures in pituitary glands of obese mice and humans.

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Introduction: Individuals with Turner syndrome (TS) are at increased risk of developing diabetes mellitus (DM). Currently, annual DM screening with hemoglobin A1c (HbA1c) with or without fasting blood glucose (FBG) is recommended starting at age 10. However, the optimal DM screening for individuals with TS is not known.

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Downregulation of endothelial Sirtuin1 (Sirt1) in insulin resistant states contributes to vascular dysfunction. Furthermore, Sirt1 deficiency in skeletal myocytes promotes insulin resistance. Here, we show that deletion of endothelial Sirt1, while impairing endothelial function, paradoxically improves skeletal muscle insulin sensitivity.

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While the immunogenicity of SARS-CoV-2 vaccines has been well described in adults, pediatric populations have been less studied. In particular, children with type 1 diabetes are generally at elevated risk for more severe disease after infections, but are understudied in terms of COVID-19 and SARS-CoV-2 vaccine responses. We investigated the immunogenicity of COVID-19 mRNA vaccinations in 35 children with type 1 diabetes (T1D) and 23 controls and found that these children develop levels of SARS-CoV-2 neutralizing antibody titers and spike protein-specific T cells comparable to nondiabetic children.

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Article Synopsis
  • Cystic fibrosis (CF) is a genetic disorder caused by mutations in the CFTR gene, leading to dysfunction in various organs, particularly affecting salt and water balance, resulting in damage over time.
  • CF-related diabetes (CFRD) develops due to pancreatic exocrine damage, affecting about 20% of teens and 50% of adults with CF, and is associated with higher health risks.
  • A scientific workshop was held in June 2021 to address gaps in understanding CFRD and plan future research directions, especially with the emergence of CFTR modulators that may change treatment outcomes.
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Cystic fibrosis (CF) is a recessive disorder arising from mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) protein. CFTR is expressed in numerous tissues, with high expression in the airways, small and large intestine, pancreatic and hepatobiliary ducts, and male reproductive tract. CFTR loss in these tissues disrupts regulation of salt, bicarbonate, and water balance across their epithelia, resulting in a systemic disorder with progressive organ dysfunction and damage.

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Turner syndrome (TS) is a common chromosomal disorder resulting from complete or partial absence of the second sex chromosome. Hyperglycemia, ranging from impaired glucose tolerance (IGT) to diabetes mellitus (DM), is common in TS. DM in individuals with TS is associated with an 11-fold excess in mortality.

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Background: Diabetes is prevalent among people with CF (PwCF) and associated with worse clinical outcomes. CFTR modulators are highly effective in improving the disease course of CF. However, the effects of elexacaftor/tezacaftor/ivacaftor (ETI) on glucose metabolism in PwCF are unclear.

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Persons with cystic fibrosis (CF) exhibit a unique alteration of fatty acid composition, marked especially among polyunsaturates by relative deficiency of linoleic acid and excess of Mead acid. Relative deficiency of docosahexaenoic acid is variably found. However, the initial development of these abnormalities is not understood.

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Cystic fibrosis-related diabetes (CFRD) is one the most common comorbidities in cystic fibrosis (CF). Pancreatic oxidative stress has been postulated in the pathogenesis of CFRD, but no studies have been done to show an association. The main obstacle is the lack of suitable animal models and no immediate availability of pancreas tissue in humans.

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Type 2 diabetes is associated with insulin resistance, impaired pancreatic β-cell insulin secretion, and nonalcoholic fatty liver disease. Tissue-specific SWELL1 ablation impairs insulin signaling in adipose, skeletal muscle, and endothelium, and impairs β-cell insulin secretion and glycemic control. Here, we show that I and SWELL1 protein are reduced in adipose and β-cells in murine and human diabetes.

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Article Synopsis
  • - A study examined caregivers of youth with type 1 diabetes (T1D) to see how often they review glycemic trends and adjust insulin accordingly, finding only 19% of caregivers responded to the survey.
  • - Caregivers who did review glucose data tended to have younger children and were more likely to use continuous glucose monitors (CGM), but this did not significantly improve their child’s HbA1c levels.
  • - The results suggest that actively reviewing glucose data and making insulin adjustments can lower HbA1c levels, although barriers still exist for caregivers, even among those using CGM.
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Type 1 diabetes and insulinoma can co-occur in pediatric patients and may present with episodes of hypo- and hyperglycemia, significant glycemic variability, and weight gain. Surgical resection leads to development of fulminant diabetes.

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Background: Cystic fibrosis (CF) related diabetes is the most common comorbidity for CF patients and associated with islet dysfunction. Exocrine pancreas remodeling in CF alters the microenvironment in which islets reside. Since CFTR is mainly expressed in pancreatic ductal epithelium, we hypothesized altered CF ductal secretions could impact islet function through paracrine signals.

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Background: /Objectives: The pathogenesis of hyperglycemia during acute pancreatitis (AP) remains unknown due to inaccessibility of human tissues and lack of animal models. We aimed to develop an animal model to study the mechanisms of hyperglycemia and impaired glucose tolerance in AP.

Methods: We injected ferrets with intraperitoneal cerulein (50 μg/kg, 9 hourly injections) or saline.

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Aberrant redox signaling underlies the pathophysiology of many chronic metabolic diseases, including type 2 diabetes (T2D). Methodologies aimed at rebalancing systemic redox homeostasis have had limited success. A noninvasive, sustained approach would enable the long-term control of redox signaling for the treatment of T2D.

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