Publications by authors named "Virtue S"

Background: Access to liver transplantation (LT) is affected by geographic disparities. Higher waitlist mortality is observed in patients residing farther from LT centres, but the impact of distance on post-LT outcomes is unclear.

Aims: To evaluate whether the distance LT recipients reside from their LT centre affects graft and patient outcomes.

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Lipid metabolism is recognised as being central to growth, disease and health. Lipids, therefore, have an important place in current research on globally significant topics such as food security and biodiversity loss. However, answering questions in these important fields of research requires not only identification and measurement of lipids in a wider variety of sample types than ever before, but also hypothesis-driven analysis of the resulting 'big data'.

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Background: Obesity rates have nearly tripled in the past 50 years, and by 2030 more than 1 billion individuals worldwide are projected to be obese. This creates a significant economic strain due to the associated non-communicable diseases. The root cause is an energy expenditure imbalance, owing to an interplay of lifestyle, environmental, and genetic factors.

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Obesity is associated with low-grade inflammation and insulin resistance (IR). The contribution of adipose tissue (AT) and hepatic inflammation to IR remains unclear. We conducted a study across three cohorts to investigate this relationship.

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The in vitro oxygen microenvironment profoundly affects the capacity of cell cultures to model physiological and pathophysiological states. Cell culture is often considered to be hyperoxic, but pericellular oxygen levels, which are affected by oxygen diffusivity and consumption, are rarely reported. Here, we provide evidence that several cell types in culture actually experience local hypoxia, with important implications for cell metabolism and function.

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Background: Cancer affects patients and their families, but few data are available on factors associated with diversity of family structures among patients with cancer. Family is a source of both support and responsibility that must be understood to support patients and their families.

Methods: Pooled data (2004-2015) from the National Health Interview Study were used to compare characteristics of cancer survivors with and without minor children and differences by sex and race/ethnicity among survivors with minor children.

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Article Synopsis
  • Metformin is commonly used during pregnancy to treat gestational diabetes, but its effects on placental metabolism are not well understood, prompting the need for research into its impact on placental functions.
  • Studies conducted on trophoblasts (cells from the placenta) showed that metformin treatment reduced oxidative phosphorylation, indicating altered energy production in the placenta.
  • Additionally, metformin increased glycolysis and triglyceride concentrations while significantly decreasing fatty acid oxidation in trophoblasts, suggesting profound metabolic changes due to the drug.
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Article Synopsis
  • The study looks at how the outer structure of fat tissue, called the extracellular matrix (ECM), changes in brown fat (BAT) and how it affects body temperature regulation and obesity.
  • Researchers found that when mice eat a high-fat diet, it causes problems in the brown fat, leading to inflammation and less fat-burning ability.
  • The findings suggest that understanding these changes in ECM can help explain why brown fat doesn't work properly in people with obesity.
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Mitochondrial dysfunction has been reported in obesity and insulin resistance, but primary genetic mitochondrial dysfunction is generally not associated with these, arguing against a straightforward causal relationship. A rare exception, recently identified in humans, is a syndrome of lower body adipose loss, leptin-deficient severe upper body adipose overgrowth, and insulin resistance caused by the p.Arg707Trp mutation in , encoding mitofusin 2.

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Article Synopsis
  • Obesity in humans and mice is linked to increased levels of the hormones GDF15 and FGF21, which are associated with weight loss and improved metabolism but their specific roles in the context of overfeeding are not fully understood.
  • Research using knockout mouse models and human tissue analysis reveals that both GDF15 and FGF21 primarily come from the liver during obesity, not from fat or muscle tissues.
  • Deleting both GDF15 and FGF21 does not lead to more weight gain on a high-fat diet but increases liver fat and insulin resistance compared to isolating the deletion of GDF15, indicating that these hormones help manage liver stress during overfeeding.
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Brown adipose tissue (BAT) thermogenesis affects energy balance, and thereby it has the potential to induce weight loss and to prevent obesity. Here, we document a macroautophagic/autophagic-dependent mechanism of peroxisome proliferator-activated receptor gamma (PPARG) activity regulation that induces brown adipose differentiation and thermogenesis and that is mediated by TP53INP2. Disruption of TP53INP2-dependent autophagy reduced brown adipogenesis in cultured cells.

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Resulting from impaired collagen turnover, fibrosis is a hallmark of adipose tissue (AT) dysfunction and obesity-associated insulin resistance (IR). Prolidase, also known as peptidase D (PEPD), plays a vital role in collagen turnover by degrading proline-containing dipeptides but its specific functional relevance in AT is unknown. Here we show that in human and mouse obesity, PEPD expression and activity decrease in AT, and PEPD is released into the systemic circulation, which promotes fibrosis and AT IR.

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Objective: Polyunsaturated fatty acid (PUFA) supplements have been trialled as a treatment for a number of conditions and produced a variety of results. This variety is ascribed to the supplements, that often comprise a mixture of fatty acids, and to different effects in different organs. In this study, we tested the hypothesis that the supplementation of individual PUFAs has system-level effects that are dependent on the molecular structure of the PUFA.

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Macrophages exhibit a spectrum of activation states ranging from classical to alternative activation. Alternatively, activated macrophages are involved in diverse pathophysiological processes such as confining tissue parasites, improving insulin sensitivity or promoting an immune-tolerant microenvironment that facilitates tumour growth and metastasis. Recently, the metabolic regulation of macrophage function has come into focus as both the classical and alternative activation programmes require specific regulated metabolic reprogramming.

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Neuronatin (Nnat) has previously been reported to be part of a network of imprinted genes downstream of the chromatin regulator Trim28. Disruption of Trim28 or of members of this network, including neuronatin, results in an unusual phenotype of a bimodal body weight. To better characterise this variability, we examined the key contributors to energy balance in Nnat mice that carry a paternal null allele and do not express Nnat.

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Detailed molecular analysis is of increasing importance in research into the regulation of biochemical pathways, organismal growth and disease. Lipidomics in particular is increasingly sought after as it provides insight into molecular species involved in energy storage, signalling and fundamental cellular structures. This has led to the use of a range of tools and techniques to acquire lipidomics data.

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Dysfunction of adipocytes and adipose tissue is a primary defect in obesity and obesity-associated metabolic diseases. Interferon regulatory factor 3 (IRF3) has been implicated in adipogenesis. However, the role of IRF3 in obesity and obesity-associated disorders remains unclear.

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Human brown adipose tissue (BAT) volume has consistently been claimed to be inversely associated with whole-body adiposity. However, recent advances in the assessment of human BAT suggest that previously reported associations may have been biased. The present cross-sectional study investigates the association of BAT volume, mean radiodensity, and F-fluorodeoxyglucose (F-FDG) uptake (assessed via a static positron emission tomography [PET]-computed tomography [CT] scan after a 2-h personalized cold exposure) with whole-body adiposity (measured by DXA) in 126 young adults (42 men and 84 women; mean ± SD BMI 24.

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When exposed to nutrient excess and insulin resistance, pancreatic β-cells undergo adaptive changes in order to maintain glucose homeostasis. The role that growth control genes, highly expressed in early pancreas development, might exert in programming β-cell plasticity in later life is a poorly studied area. The imprinted Igf2 (insulin-like growth factor 2) gene is highly transcribed during early life and has been identified in recent genome-wide association studies as a type 2 diabetes susceptibility gene in humans.

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Objective: Neuroimmune interactions between the sympathetic nervous system (SNS) and macrophages are required for the homeostasis of multiple tissues, including the adipose tissue. It has been proposed that the SNS maintains adipose tissue macrophages (ATMs) in an anti-inflammatory state via direct norepinephrine (NE) signaling to macrophages. This study aimed to investigate the physiological importance of this paradigm by utilizing a mouse model in which the adrenergic signaling from the SNS to macrophages, but not to other adipose tissue cells, was disrupted.

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Brown and beige adipose tissue are emerging as distinct endocrine organs. These tissues are functionally associated with skeletal muscle, adipose tissue metabolism and systemic energy expenditure, suggesting an interorgan signaling network. Using metabolomics, we identify 3-methyl-2-oxovaleric acid, 5-oxoproline, and β-hydroxyisobutyric acid as small molecule metabokines synthesized in browning adipocytes and secreted via monocarboxylate transporters.

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Objective: Non-alcoholic fatty liver disease (NAFLD) is a silent pandemic associated with obesity and the metabolic syndrome, and also increases cardiovascular- and cirrhosis-related morbidity and mortality. A complete understanding of adaptive compensatory metabolic programmes that modulate non-alcoholic steatohepatitis (NASH) progression is lacking.

Methods And Results: Transcriptomic analysis of liver biopsies in patients with NASH revealed that NASH progression is associated with rewiring of metabolic pathways, including upregulation of de novo lipid/cholesterol synthesis and fatty acid remodelling.

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