Publications by authors named "Bryan C Bergman"

Objective: Circulating lipids are linked with insulin resistance and increased cardiovascular disease risk. We previously reported that dihydroceramides, a specific type of sphingolipid, are elevated in insulin-resistant individuals; however, little is known regarding whether insulin-sensitizing lifestyle interventions can improve profiles of sphingolipids and other lipid species.

Methods: A total of 21 individuals with obesity participated in a 3-month lifestyle intervention of combined weight loss and exercise training.

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  • Peripancreatic adipose tissue (PAT), which accumulates with obesity, negatively affects metabolic health and beta cell function, highlighting its significance compared to subcutaneous adipose tissue (SAT).
  • PAT secretes higher levels of inflammatory substances and certain adipokines linked to poor metabolic outcomes, with variations in islet insulin secretion observed between male and female donors.
  • RNA sequencing reveals that PAT influences gene transcription and lipid metabolism in islets in a sex-dependent manner, suggesting different metabolic impacts compared to SAT.
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  • Intracellular accumulation of ceramide in muscle cells may be a key factor in insulin resistance linked to type 2 diabetes, particularly influenced by oxidised phosphatidylcholine found in oxidised LDL.
  • A study involving 58 individuals showed that higher levels of oxidised phosphatidylcholine are associated with decreased insulin sensitivity and increased ceramide levels in skeletal muscle.
  • Experiments on rat muscle cells revealed that specific oxidised phosphatidylcholine species, like POVPC, promote ceramide accumulation, trigger inflammation, and contribute to insulin resistance.
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  • The study aimed to explore how mesenchymal stem cell (MSC) lipid metabolism and maternal factors, aside from body mass, might impact the risk of obesity in children.
  • Researchers analyzed MSCs from infants of mothers with obesity or normal weight, using techniques like lipidomics and measuring various metabolic indicators during pregnancy.
  • Findings revealed distinct MSC clusters linked to maternal metabolic health, suggesting that these clusters could potentially forecast child obesity at a young age, although further validation is needed.
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Elevated skeletal muscle diacylglycerols (DAGs) and ceramides can impair insulin signaling, and acylcarnitines (acylCNs) reflect impaired mitochondrial fatty acid oxidation, thus, the intramuscular lipid profile is indicative of insulin resistance. Acute (i.e.

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Subcutaneous white adipose tissue (scWAT) is a dynamic storage and secretory organ that regulates systemic homeostasis, yet the impact of endurance exercise training (ExT) and sex on its molecular landscape is not fully established. Utilizing an integrative multi-omics approach, and leveraging data generated by the Molecular Transducers of Physical Activity Consortium (MoTrPAC), we show profound sexual dimorphism in the scWAT of sedentary rats and in the dynamic response of this tissue to ExT. Specifically, the scWAT of sedentary females displays -omic signatures related to insulin signaling and adipogenesis, whereas the scWAT of sedentary males is enriched in terms related to aerobic metabolism.

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Physical activity, including structured exercise, is associated with favorable health-related chronic disease outcomes. Although there is evidence of various molecular pathways that affect these responses, a comprehensive molecular map of these molecular responses to exercise has not been developed. The Molecular Transducers of Physical Activity Consortium (MoTrPAC) is a multicenter study designed to isolate the effects of structured exercise training on the molecular mechanisms underlying the health benefits of exercise and physical activity.

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Background: Exposure to intrauterine obesity can disrupt clock gene rhythmicity in animal models. The aim of this pilot study was to determine if maternal obesity alters rhythmic expression of core clock in mesenchymal stem cells (MSCs) from umbilical cords of human infants born to mothers with obesity (Ob-MSC) vs. normal weight (NW-MSC).

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  • * Research reveals that a deficiency in coenzyme Q (CoQ) and high levels of ceramide in skeletal muscle mitochondria lead to mitochondrial dysfunction, contributing to IR.
  • * Reducing mitochondrial ceramide and increasing CoQ levels may help prevent IR and could inform new treatments for metabolic disorders and related conditions.
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Despite the common practice of switching patients from one medicine to another—to improve efficacy, safety, or tolerability—guidance on how to do so is uncommon. During this time of global shortage of glucagon‐like peptide‐1 receptor agonist (GLP‐1 RA) ± glucose‐dependent insulinotropic polypeptide (GIP) RA therapies, this research letter offers a quick clinical reference of rough equivalency between GLP‐1 ± GIP RA for A1c and body weight reduction in people with type 2 diabetes.

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Unlabelled: Maternal consumption of a Western-style diet (mWD) during pregnancy alters fatty acid metabolism and reduces insulin sensitivity in fetal skeletal muscle. The long-term impact of these fetal adaptations and the pathways underlying disordered lipid metabolism are incompletely understood. Therefore, we tested whether a mWD chronically fed to lean, insulin-sensitive adult Japanese macaques throughout pregnancy and lactation would impact skeletal muscle oxidative capacity and lipid metabolism in adolescent offspring fed a postweaning (pw) Western-style diet (WD) or control diet (CD).

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Stimulation of adipocyte β-adrenergic receptors (β-ARs) induces expression of uncoupling protein 1 (UCP1), promoting nonshivering thermogenesis. Association of β-ARs with a lysine-myristoylated form of A kinase-anchoring protein 12 (AKAP12, also known as gravin-α) is required for downstream signaling that culminates in UCP1 induction. Conversely, demyristoylation of gravin-α by histone deacetylase 11 (HDAC11) suppresses this pathway.

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Unlabelled: Sphingolipids are thought to promote skeletal muscle insulin resistance. Deoxysphingolipids (dSLs) are atypical sphingolipids that are increased in the plasma of individuals with type 2 diabetes and cause β-cell dysfunction in vitro. However, their role in human skeletal muscle is unknown.

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Article Synopsis
  • - Sphingolipids, particularly 1-Deoxysphingolipids (dSL), are linked to insulin resistance in skeletal muscle and are found at elevated levels in individuals with obesity and type 2 diabetes compared to athletes and lean individuals.
  • - The study shows that high dSL levels correlate with decreased insulin sensitivity and are associated with increased inflammation and disrupted insulin signaling in muscle cells.
  • - Reducing dSL levels through weight loss and exercise improves insulin sensitivity, indicating dSL could be targeted for treatments aimed at preventing or managing type 2 diabetes.
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Maternal overnutrition increases inflammatory and metabolic disease risk in postnatal offspring. This constitutes a major public health concern due to increasing prevalence of these diseases, yet mechanisms remain unclear. Here, using nonhuman primate models, we show that maternal Western-style diet (mWSD) exposure is associated with persistent pro-inflammatory phenotypes at the transcriptional, metabolic, and functional levels in bone marrow-derived macrophages (BMDMs) from 3-year-old juvenile offspring and in hematopoietic stem and progenitor cells (HSPCs) from fetal and juvenile bone marrow and fetal liver.

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  • Stimulation of β-adrenergic receptors (β-ARs) in fat cells leads to increased expression of uncoupling protein 1 (UCP1), which helps generate heat without shivering.
  • The interaction of β-ARs with a specific form of the protein A-kinase anchoring protein 12 (AKAP12/gravin-α) is essential for activating UCP1, while HDAC11 can inhibit this pathway by removing myristoylation from gravin-α.
  • Deleting HDAC11 in fat cells or using the selective inhibitor FT895 enhances UCP1 expression and body temperature, even in cases where β-AR signaling is disrupted, suggesting that targeting HDAC11 could
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  • * New findings reveal that high levels of ceramides in muscle cells lead to coenzyme Q (CoQ) depletion and mitochondrial issues, contributing to IR.
  • * Reducing ceramide levels or supplementing with CoQ can improve mitochondrial function and insulin sensitivity, suggesting a potential pathway for developing new treatments for IR and related disorders.
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Aims/hypothesis: Although insulin resistance often leads to type 2 diabetes mellitus, its early stages are often unrecognised, thus reducing the probability of successful prevention and intervention. Moreover, treatment efficacy is affected by the genetics of the individual. We used gene expression profiles from a cross-sectional study to identify potential candidate genes for the prediction of diabetes risk and intervention response.

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Intermuscular adipose tissue (IMAT) is a distinct adipose depot described in early reports as a 'fatty replacement' or 'muscle fat infiltration' that was linked to ageing and neuromuscular disease. Later studies quantifying IMAT with modern in vivo imaging methods (computed tomography and magnetic resonance imaging) revealed that IMAT is proportionately higher in men and women with type 2 diabetes mellitus and the metabolic syndrome than in people without these conditions and is associated with insulin resistance and poor physical function with ageing. In parallel, agricultural research has provided extensive insight into the role of IMAT and other muscle lipids in muscle (that is, meat) quality.

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Adipose tissue secretions are depot-specific and vary based on anatomical location. Considerable attention has been focused on visceral (VAT) and subcutaneous (SAT) adipose tissue with regard to metabolic disease, yet our knowledge of the secretome from these depots is incomplete. We conducted a comprehensive analysis of VAT and SAT secretomes in the context of metabolic function.

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Serum ceramides, especially C16:0 and C18:0 species, are linked to CVD risk and insulin resistance, but details of this association are not well understood. We performed this study to quantify a broad range of serum sphingolipids in individuals spanning the physiologic range of insulin sensitivity and to determine if dihydroceramides cause insulin resistance in vitro. As expected, we found that serum triglycerides were significantly greater in individuals with obesity and T2D compared with athletes and lean individuals.

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Adipose tissue secretes an abundance of lipid and protein mediators, and this secretome is depot-specific, with local and systemic effects on metabolic regulation. Intermuscular adipose tissue (IMAT) accumulates within the skeletal muscle compartment in obesity, and is associated with insulin resistance and metabolic disease. While the human IMAT secretome decreases insulin sensitivity in vitro, its composition is entirely unknown.

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Preclinical rodent and nonhuman primate models investigating maternal obesity have highlighted the importance of the intrauterine environment in the development of insulin resistance in offspring; however, it remains unclear if these findings can be translated to humans. To investigate possible intrauterine effects in humans, we isolated mesenchymal stem cells (MSCs) from the umbilical cord tissue of infants born to mothers of normal weight or mothers with obesity. Insulin-stimulated glycogen storage was determined in MSCs undergoing myogenesis in vitro.

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Purpose: To train and test a machine learning model to automatically measure mid-thigh muscle cross-sectional area (CSA) to provide rapid estimation of appendicular lean mass (ALM) and predict knee extensor torque of obese adults.

Methods: Obese adults [body mass index (BMI) = 30-40 kg/m, age = 30-50 years] were enrolled for this study. Participants received full-body dual-energy X-ray absorptiometry (DXA), mid-thigh MRI, and completed knee extensor and flexor torque assessments isokinetic dynamometer.

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Alterations in adipose tissue composition and function are associated with obesity and contribute to the development of type 2 diabetes. While the significance of this relationship has been cemented, our understanding of the multifaceted role of adipose tissue in metabolic heath and disease continues to evolve and expand. Heterogenous populations of cells that make up adipose tissue throughout the body generate diverse secretomes containing a mosaic of bioactive compounds with vast structural and signaling capabilities.

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