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Lewis GF. Invited Commentary regarding Manuscript JLR-D-23-00602R1. Revised title 'Fatty acid malabsorption followed by chylomicron malformation, not pancreatic insufficiency, cause metabolic defects in cystic fibrosis', by Teng L et al. J Lipid Res 2024:100549. [PMID: 38649097 DOI: 10.1016/j.jlr.2024.100549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024] Open
Affiliation(s)
- Gary F Lewis
- Division of Endocrinology, Departments of Medicine and Physiology, University of Toronto, Toronto, ON, M5G 2C4, Canada.
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Lewis GF, Mulvihill EE. The Complexities of Intestinal Lipoprotein Production in Insulin Resistance and Diabetes: Revisiting a 2010 Diabetes Classic by Pavlic et al. Diabetes 2024; 73:335-337. [PMID: 38377446 DOI: 10.2337/dbi23-0036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Accepted: 12/19/2023] [Indexed: 02/22/2024]
Affiliation(s)
- Gary F Lewis
- Department of Medicine and Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Division of Endocrinology and Metabolism, University of Toronto, Toronto, Ontario, Canada
| | - Erin E Mulvihill
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
- University of Ottawa Heart Institute, Ottawa, Ontario, Canada
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Syed-Abdul MM, Tian L, Lewis GF. Unanticipated Enhancement of Intestinal TG Output by Apoc3 ASO Inhibition. Arterioscler Thromb Vasc Biol 2023; 43:2133-2142. [PMID: 37675633 DOI: 10.1161/atvbaha.123.319765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 08/22/2023] [Indexed: 09/08/2023]
Abstract
BACKGROUND The objective of this study was to investigate whether apoC3 (apolipoprotein C3) inhibition with an antisense oligonucleotide (ASO) modulates intestinal triglyceride secretion. METHODS Sprague-Dawley rats were treated with subcutaneous injections of apoC3 ASO 25 mg/kg twice weekly or inactive ASO for 4 weeks before the assessment of lymph flow, triglyceride and apoB48 (apolipoprotein B48) appearance in the lymph. Rats were surgically implanted with catheters in the mesenteric lymph duct and duodenum. Following an overnight fast, an intraduodenal lipid bolus (1.5-mL intralipid) was administered. Lymph fluid was collected for the following 4 hours to compare effects on lymph flow, lymph triglyceride and apoB48 concentration, and secretion. To assess suppression of apoC3 expression and protein abundance by apoC3 ASO compared with inactive ASO (placebo), intestinal and hepatic tissues were collected from a subset of animals before (fasting) and after an enteral lipid bolus (post-lipid). RESULTS ApoC3 ASO significantly reduced apoC3 mRNA expression in the liver compared with inactive ASO (fasting: 42%, P=0.0048; post-lipid: 66%, P<0.001) and in the duodenum (fasting: 29%, P=0.0424; post-lipid: 53%, P=0.0120). As expected, plasma triglyceride also decreased significantly (fasting: 74%, P<0.001; post-lipid: 33%, P=0.0276). Lymph flow and cumulative lymph volume remained unchanged following apoC3 ASO therapy; however, lymph triglyceride, but not apoB48 output, increased by 38% (ANOVA, P<0.001). Last, no changes were observed in stool triglyceride, intestinal fat (quantified via oil red O staining), and expression of mRNAs involved in triglyceride synthesis, lipid droplet formation, and chylomicron transport and secretion. CONCLUSIONS Despite the marked reduction in plasma triglyceride concentration that occurs with apoC3 ASO inhibition, intestinal triglyceride output surprisingly increased rather than decreased. These data demonstrate that the reduction of intestinal triglyceride output does not contribute to the potent plasma triglyceride-lowering observed with this novel therapy for hypertriglyceridemia. Further studies are required to explore the mechanism of this intestinal effect.
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Affiliation(s)
- Majid Mufaqam Syed-Abdul
- Division of Endocrinology, Department of Medicine and Banting & Best Diabetes Centre, University of Toronto, ON, Canada
| | - Lili Tian
- Division of Endocrinology, Department of Medicine and Banting & Best Diabetes Centre, University of Toronto, ON, Canada
| | - Gary F Lewis
- Division of Endocrinology, Department of Medicine and Banting & Best Diabetes Centre, University of Toronto, ON, Canada
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Syed-Abdul MM, Stahel P, Zembroski A, Tian L, Xiao C, Nahmias A, Bookman I, Buhman KK, Lewis GF. Glucagon-like peptide-2 acutely enhances chylomicron secretion in humans without mobilizing cytoplasmic lipid droplets. J Clin Endocrinol Metab 2022; 108:1084-1092. [PMID: 36458872 DOI: 10.1210/clinem/dgac690] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 11/21/2022] [Accepted: 11/29/2022] [Indexed: 12/05/2022]
Abstract
CONTEXT A portion of ingested fats are retained in the intestine for many hours before they are mobilized and secreted in chylomicron (CM) particles. Factors like glucagon-like peptide-2 (GLP-2) and glucose can mobilize these stored intestinal lipids and enhance CM secretion. We have recently demonstrated in rodents that GLP-2 acutely enhances CM secretion by mechanisms that do not involve the canonical CM synthetic assembly and secretory pathways. OBJECTIVE To further investigate the mechanism of GLP-2's potent intestinal lipid mobilizing effect, we examined intracellular cytoplasmic lipid droplets (CLDs) in intestinal biopsies of humans administered GLP-2 or placebo. DESIGN, SETTING, PATIENTS, AND INTERVENTIONS A single dose of placebo or GLP-2 was administered subcutaneously five hours after ingesting a high-fat bolus. In one subset of participants, plasma samples were collected to quantify lipid and lipoprotein concentrations for 3 hours post-placebo or GLP-2. In another subset, a duodenal biopsy was obtained one-hour post-placebo or GLP-2 administration for transmission electron microscopy (TEM) and proteomic analysis. RESULTS GLP-2 significantly increased plasma-TG by 46% (P = 0.009), mainly in CM-sized particles (CM-TG) by 133% (P = 0.003), without reducing duodenal CLD size or number. Several proteins of interest were identified that require further investigation to elucidate their potential role in GLP-2-mediated CM secretion. CONCLUSIONS Unlike glucose that mobilizes enterocyte CLDs and enhances CM secretion, GLP-2 acutely increased plasma CMs without significant mobilization of CLDs, supporting our previous findings that GLP-2 does not act directly on enterocytes to enhance CM secretion and most likely mobilizes secreted CMs in the lamina propria and lymphatics.
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Affiliation(s)
- Majid Mufaqam Syed-Abdul
- Departments of Medicine and Physiology and Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, CANADA
| | - Priska Stahel
- Departments of Medicine and Physiology and Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, CANADA
| | - Alyssa Zembroski
- Department of Nutrition Science, Purdue University, West Lafayette, Indiana, USA
| | - Lili Tian
- Departments of Medicine and Physiology and Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, CANADA
| | - Changting Xiao
- Department of Anatomy, Physiology and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, CANADA
| | - Avital Nahmias
- Maccabi Healthcare Services, Endocrinology Division, Tel Aviv, Israel
| | - Ian Bookman
- Kensington Screening Clinic, Department of Medicine, University of Toronto, Toronto, Ontario, CANADA
| | - Kimberly K Buhman
- Department of Nutrition Science, Purdue University, West Lafayette, Indiana, USA
| | - Gary F Lewis
- Departments of Medicine and Physiology and Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, CANADA
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Tian L, Syed-Abdul MM, Stahel P, Lewis GF. Enteral glucose, absorbed and metabolized, potently enhances mesenteric lymph flow in chow- and high-fat-fed rats. Am J Physiol Gastrointest Liver Physiol 2022; 323:G331-G340. [PMID: 35916412 DOI: 10.1152/ajpgi.00095.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A portion of absorbed dietary triglycerides (TG) is retained in the intestine after the postprandial period, within intracellular and extracellular compartments. This pool of TG can be mobilized in response to several stimuli, including oral glucose. The objective of this study was to determine whether oral glucose must be absorbed and metabolized to mobilize TG in rats and whether high-fat feeding, a model of insulin resistance, alters the lipid mobilization response to glucose. Lymph flow, TG concentration, TG output, and apolipoprotein B48 (apoB48) concentration and output were assessed after an intraduodenal lipid bolus in rats exposed to the following intraduodenal administrations 5 h later: saline (placebo), glucose, 2-deoxyglucose (2-DG, absorbed but not metabolized), or glucose + phlorizin (intestinal glucose absorption inhibitor). Glucose alone, but not 2-DG or glucose + phlorizin treatments, stimulated lymph flow, TG output, and apoB48 output compared with placebo. The effects of glucose in high-fat-fed rats were similar to those in chow-fed rats. In conclusion, glucose must be both absorbed and metabolized to enhance lymph flow and intestinal lipid mobilization. This effect is qualitatively and quantitatively similar in high-fat- and chow-fed rats. The precise signaling mechanism whereby enteral glucose enhances lymph flow and mobilizes enteral lipid remains to be determined.NEW & NOTEWORTHY Glucose potently enhances mesenteric lymph flow in chow- and high-fat-fed rats. The magnitude of glucose effect on lymph flow is no different in chow- and high-fat-fed rats. Glucose must be absorbed and metabolized to enhance lymph flow and mobilize intestinal lipid.
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Affiliation(s)
- Lili Tian
- Division of Endocrinology, Department of Medicine and Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Majid Mufaqam Syed-Abdul
- Division of Endocrinology, Department of Medicine and Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Priska Stahel
- Division of Endocrinology, Department of Medicine and Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Gary F Lewis
- Division of Endocrinology, Department of Medicine and Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
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Syed-Abdul MM, Stahel P, Tian L, Xiao C, Nahmias A, Lewis GF. Glucagon-like peptide-2 mobilization of intestinal lipid does not require canonical enterocyte chylomicron synthetic machinery. Biochim Biophys Acta Mol Cell Biol Lipids 2022; 1867:159194. [DOI: 10.1016/j.bbalip.2022.159194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 05/25/2022] [Accepted: 05/31/2022] [Indexed: 11/16/2022]
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Ghanem M, Lewis GF, Xiao C. Recent advances in cytoplasmic lipid droplet metabolism in intestinal enterocyte. Biochim Biophys Acta Mol Cell Biol Lipids 2022; 1867:159197. [PMID: 35820577 DOI: 10.1016/j.bbalip.2022.159197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 06/03/2022] [Accepted: 06/14/2022] [Indexed: 11/30/2022]
Abstract
Processing of dietary fats in the intestine is a highly regulated process that influences whole-body energy homeostasis and multiple physiological functions. Dysregulated lipid handling in the intestine leads to dyslipidemia and atherosclerotic cardiovascular disease. In intestinal enterocytes, lipids are incorporated into lipoproteins and cytoplasmic lipid droplets (CLDs). Lipoprotein synthesis and CLD metabolism are inter-connected pathways with multiple points of regulation. This review aims to highlight recent advances in the regulatory mechanisms of lipid processing in the enterocyte, with particular focus on CLDs. In-depth understanding of the regulation of lipid metabolism in the enterocyte may help identify therapeutic targets for the treatment and prevention of metabolic disorders.
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Affiliation(s)
- Murooj Ghanem
- Department of Anatomy, Physiology and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - Gary F Lewis
- Departments of Medicine and Physiology, University of Toronto, and University Health Network, Toronto, ON, Canada
| | - Changting Xiao
- Department of Anatomy, Physiology and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada.
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Abstract
PURPOSE OF REVIEW Lymphatics are known to have active, regulated pumping by smooth muscle cells that enhance lymph flow, but whether active regulation of lymphatic pumping contributes significantly to the rate of appearance of chylomicrons (CMs) in the blood circulation (i.e., CM production rate) is not currently known. In this review, we highlight some of the potential mechanisms by which lymphatics may regulate CM production. RECENT FINDINGS Recent data from our lab and others are beginning to provide clues that suggest a more active role of lymphatics in regulating CM appearance in the circulation through various mechanisms. Potential contributors include apolipoproteins, glucose, glucagon-like peptide-2, and vascular endothelial growth factor-C, but there are likely to be many more. SUMMARY The digested products of dietary fats absorbed by the small intestine are re-esterified and packaged by enterocytes into large, triglyceride-rich CM particles or stored temporarily in intracellular cytoplasmic lipid droplets. Secreted CMs traverse the lamina propria and are transported via lymphatics and then the blood circulation to liver and extrahepatic tissues, where they are stored or metabolized as a rich energy source. Although indirect data suggest a relationship between lymphatic pumping and CM production, this concept requires more experimental evidence before we can be sure that lymphatic pumping contributes significantly to the rate of CM appearance in the blood circulation.
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Affiliation(s)
- Majid M Syed-Abdul
- Departments of Medicine and Physiology and Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Lili Tian
- Departments of Medicine and Physiology and Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Changting Xiao
- Department of Anatomy, Physiology and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Gary F Lewis
- Departments of Medicine and Physiology and Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
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Dotan I, Yang J, Ikeda J, Roth Z, Pollock-Tahiri E, Desai H, Sivasubramaniyam T, Rehal S, Rapps J, Li YZ, Le H, Farber G, Alchami E, Xiao C, Karim S, Gronda M, Saikali MF, Tirosh A, Wagner KU, Genest J, Schimmer AD, Gupta V, Minden MD, Cummins CL, Lewis GF, Robbins C, Jongstra-Bilen J, Cybulsky M, Woo M. Macrophage Jak2 deficiency accelerates atherosclerosis through defects in cholesterol efflux. Commun Biol 2022; 5:132. [PMID: 35169231 PMCID: PMC8847578 DOI: 10.1038/s42003-022-03078-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2020] [Accepted: 01/26/2022] [Indexed: 12/11/2022] Open
Abstract
Atherosclerosis is a chronic inflammatory condition in which macrophages play a major role. Janus kinase 2 (JAK2) is a pivotal molecule in inflammatory and metabolic signaling, and Jak2V617F activating mutation has recently been implicated with enhancing clonal hematopoiesis and atherosclerosis. To determine the essential in vivo role of macrophage (M)-Jak2 in atherosclerosis, we generate atherosclerosis-prone ApoE-null mice deficient in M-Jak2. Contrary to our expectation, these mice exhibit increased plaque burden with no differences in macrophage proliferation, recruitment or bone marrow clonal expansion. Notably, M-Jak2-deficient bone marrow derived macrophages show a significant defect in cholesterol efflux. Pharmacologic JAK2 inhibition with ruxolitinib also leads to defects in cholesterol efflux and accelerates atherosclerosis. Liver X receptor agonist abolishes the efflux defect and attenuates the accelerated atherosclerosis that occurs with M-Jak2 deficiency. Macrophages of individuals with the Jak2V617F mutation show increased efflux which is normalized when treated with a JAK2 inhibitor. Together, M-Jak2-deficiency leads to accelerated atherosclerosis primarily through defects in cholesterol efflux from macrophages.
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Affiliation(s)
- Idit Dotan
- Toronto General Hospital Research Institute, University Health Network, Toronto, Canada.,Institute of Endocrinology, Beilinson Campus, Rabin Medical Center, Petach Tikva, Israel
| | - Jiaqi Yang
- Toronto General Hospital Research Institute, University Health Network, Toronto, Canada
| | - Jiro Ikeda
- Toronto General Hospital Research Institute, University Health Network, Toronto, Canada
| | - Ziv Roth
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, Toronto, Canada
| | - Evan Pollock-Tahiri
- Toronto General Hospital Research Institute, University Health Network, Toronto, Canada
| | - Harsh Desai
- Toronto General Hospital Research Institute, University Health Network, Toronto, Canada
| | | | - Sonia Rehal
- Toronto General Hospital Research Institute, University Health Network, Toronto, Canada
| | - Josh Rapps
- Toronto General Hospital Research Institute, University Health Network, Toronto, Canada
| | - Yu Zhe Li
- Toronto General Hospital Research Institute, University Health Network, Toronto, Canada
| | - Helen Le
- Toronto General Hospital Research Institute, University Health Network, Toronto, Canada
| | - Gedaliah Farber
- Toronto General Hospital Research Institute, University Health Network, Toronto, Canada
| | - Edouard Alchami
- Department of Immunology, University of Toronto, Toronto, Canada
| | - Changting Xiao
- Toronto General Hospital Research Institute, University Health Network, Toronto, Canada
| | - Saraf Karim
- Toronto General Hospital Research Institute, University Health Network, Toronto, Canada
| | - Marcela Gronda
- Princess Margaret Cancer Centre, University Health Network, Toronto, Canada
| | - Michael F Saikali
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, Canada
| | - Amit Tirosh
- Endocrine Cancer Genomics Center, Sheba Medical Center, Tel Hashomer, Israel
| | - Kay-Uwe Wagner
- Department of Oncology, Wayne State University School of Medicine and Tumor Biology Program, Barbara Ann Karmanos Cancer Institute, Detroit, MI, USA
| | - Jacques Genest
- Research Institute of the McGill University Health Centre, Royal Victoria Hospital, Montreal, QC, Canada
| | - Aaron D Schimmer
- Princess Margaret Cancer Centre, University Health Network, Toronto, Canada
| | - Vikas Gupta
- Princess Margaret Cancer Centre, University Health Network, Toronto, Canada
| | - Mark D Minden
- Princess Margaret Cancer Centre, University Health Network, Toronto, Canada
| | - Carolyn L Cummins
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, Canada
| | - Gary F Lewis
- Toronto General Hospital Research Institute, University Health Network, Toronto, Canada
| | - Clinton Robbins
- Toronto General Hospital Research Institute, University Health Network, Toronto, Canada.,Department of Immunology, University of Toronto, Toronto, Canada
| | - Jenny Jongstra-Bilen
- Toronto General Hospital Research Institute, University Health Network, Toronto, Canada.,Department of Immunology, University of Toronto, Toronto, Canada
| | - Myron Cybulsky
- Toronto General Hospital Research Institute, University Health Network, Toronto, Canada.,Department of Immunology, University of Toronto, Toronto, Canada
| | - Minna Woo
- Toronto General Hospital Research Institute, University Health Network, Toronto, Canada. .,Department of Immunology, University of Toronto, Toronto, Canada. .,Division of Endocrinology and Metabolism, Department of Medicine, University Health Network and Sinai Health System, University of Toronto, Toronto, Canada.
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Lewis GF, Hegele RA. Effective, disease-modifying, clinical approaches to patients with mild-to-moderate hypertriglyceridaemia. Lancet Diabetes Endocrinol 2022; 10:142-148. [PMID: 34922644 DOI: 10.1016/s2213-8587(21)00284-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 10/01/2021] [Accepted: 10/03/2021] [Indexed: 02/07/2023]
Abstract
Plasma triglyceride concentration is easily, inexpensively, and accurately measured, and when elevated is a highly informative disease marker that identifies individuals who frequently have a host of underlying metabolic, inflammatory, and atherogenic risk factors. Although this concept aligns with much that has been discussed regarding the metabolic syndrome, individuals identified with mild-to-moderate hypertriglyceridaemia on a screening lipid profile are not necessarily recognised as having features of the metabolic syndrome and frequently do not receive definitive, meaningful, disease-modifying therapy. This treatment would include (1) lifestyle modification; (2) LDL-lowering therapies to aggressively treat elevated apolipoprotein B-containing particles; (3) antihypertensive therapies that have optimal therapeutic profiles for those individuals with metabolic syndrome; (4) icosapent ethyl for those individuals at high risk, particularly patients with established atherosclerotic cardiovascular disease who have residual hypertriglyceridaemia despite treatment with appropriate LDL-lowering therapies; (5) preferential use of cardiovascular protective diabetes therapies, in individuals with diabetes; and (6) antithrombotic therapies for secondary prevention of atherosclerotic cardiovascular disease in the context of high vascular disease risk and diabetes. Several emerging therapies, such as novel weight reducing, anti-inflammatory, lipid-modifying therapies, and therapies targeting the progression of non-alcoholic fatty liver disease, could also soon enter the clinical arena for patients with mild-to-moderate hypertriglyceridaemia and associated metabolic syndrome.
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Affiliation(s)
- Gary F Lewis
- Department of Medicine and Department of Physiology, Division of Endocrinology and Metabolism, Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, Canada; Department of Medicine, Toronto General Hospital, Toronto, ON, Canada.
| | - Robert A Hegele
- Department of Medicine, Department of Biochemistry, and The Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
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Abstract
2021 to 2022 marks the one hundredth anniversary of ground-breaking research in Toronto that changed the course of what was, then, a universally fatal disease: type 1 diabetes. Some would argue that insulin's discovery by Banting, Best, Macleod, and Collip was the greatest scientific advance of the 20th century, being one of the first instances in which modern medical science was able to provide lifesaving therapy. As with all scientific discoveries, the work in Toronto built upon important advances of many researchers over the preceding decades. Furthermore, the Toronto work ushered in a century of discovery of the purification, isolation, structural characterization, and genetic sequencing of insulin, all of which influenced ongoing improvements in therapeutic insulin formulations. Here we discuss the body of knowledge prior to 1921 localizing insulin to the pancreas and establishing insulin's role in glucoregulation, and provide our views as to why researchers in Toronto ultimately achieved the purification of pancreatic extracts as a therapy. We discuss the pharmaceutical industry's role in the early days of insulin production and distribution and provide insights into why the discoverers chose not to profit financially from the discovery. This fascinating story of bench-to-beside discovery provides useful considerations for scientists now and in the future.
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Ginsberg HN, Packard CJ, Chapman MJ, Borén J, Aguilar-Salinas CA, Averna M, Ference BA, Gaudet D, Hegele RA, Kersten S, Lewis GF, Lichtenstein AH, Moulin P, Nordestgaard BG, Remaley AT, Staels B, Stroes ESG, Taskinen MR, Tokgözoğlu LS, Tybjaerg-Hansen A, Stock JK, Catapano AL. Triglyceride-rich lipoproteins and their remnants: metabolic insights, role in atherosclerotic cardiovascular disease, and emerging therapeutic strategies-a consensus statement from the European Atherosclerosis Society. Eur Heart J 2021; 42:4791-4806. [PMID: 34472586 PMCID: PMC8670783 DOI: 10.1093/eurheartj/ehab551] [Citation(s) in RCA: 263] [Impact Index Per Article: 87.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 05/21/2021] [Accepted: 07/30/2021] [Indexed: 12/20/2022] Open
Abstract
Recent advances in human genetics, together with a large body of epidemiologic, preclinical, and clinical trial results, provide strong support for a causal association between triglycerides (TG), TG-rich lipoproteins (TRL), and TRL remnants, and increased risk of myocardial infarction, ischaemic stroke, and aortic valve stenosis. These data also indicate that TRL and their remnants may contribute significantly to residual cardiovascular risk in patients on optimized low-density lipoprotein (LDL)-lowering therapy. This statement critically appraises current understanding of the structure, function, and metabolism of TRL, and their pathophysiological role in atherosclerotic cardiovascular disease (ASCVD). Key points are (i) a working definition of normo- and hypertriglyceridaemic states and their relation to risk of ASCVD, (ii) a conceptual framework for the generation of remnants due to dysregulation of TRL production, lipolysis, and remodelling, as well as clearance of remnant lipoproteins from the circulation, (iii) the pleiotropic proatherogenic actions of TRL and remnants at the arterial wall, (iv) challenges in defining, quantitating, and assessing the atherogenic properties of remnant particles, and (v) exploration of the relative atherogenicity of TRL and remnants compared to LDL. Assessment of these issues provides a foundation for evaluating approaches to effectively reduce levels of TRL and remnants by targeting either production, lipolysis, or hepatic clearance, or a combination of these mechanisms. This consensus statement updates current understanding in an integrated manner, thereby providing a platform for new therapeutic paradigms targeting TRL and their remnants, with the aim of reducing the risk of ASCVD.
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Affiliation(s)
- Henry N Ginsberg
- Department of Medicine, Vagelos College of Physicians and Surgeons, Columbia University, 630 West 168th Street, PH-10-305, New York, NY 10032, USA
| | - Chris J Packard
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, 126 University Place, Glasgow G12 8TA, UK
| | - M John Chapman
- Sorbonne University Endocrinology-Metabolism Division, Pitié-Salpetriere University Hospital, and National Institute for Health and Medical Research (INSERM), 47 Hôpital boulevard, Paris 75013, France
| | - Jan Borén
- Department of Molecular and Clinical Medicine, University of Gothenburg and Sahlgrenska University Hospital, Blå Stråket 5, Gothenburg 413 45, Sweden
| | - Carlos A Aguilar-Salinas
- Unidad de Investigación en Enfermedades Metabólicas and Departamento de Endocrinología y Metabolismo, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Vasco de Quiroga 15, Belisario Domínguez Secc 16, Tlalpan, Mexico City 14080, Mexico.,Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Ave. Morones Prieto, Monterrey, Nuevo León 3000, Mexico
| | - Maurizio Averna
- Department of Health Promotion Sciences Maternal and Infantile Care, Internal Medicine and Medical Specialities, University of Palermo, Marina Square, 61, Palermo 90133, Italy
| | - Brian A Ference
- Centre for Naturally Randomized Trials, University of Cambridge, Cambridge, UK
| | - Daniel Gaudet
- Clinical Lipidology and Rare Lipid Disorders Unit, Community Genomic Medicine Center, Department of Medicine, Université de Montréal, ECOGENE, Clinical and Translational Research Center, and Lipid Clinic, Chicoutimi Hospital, 305 Rue St Vallier, Chicoutimi, Québec G7H 5H6, Canada
| | - Robert A Hegele
- Department of Medicine and Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, 1151 Richmond Street, London, Ontario N6A 3K7, Canada
| | - Sander Kersten
- Division of Human Nutrition and Health, Wageningen University, Wageningen, the Netherlands
| | - Gary F Lewis
- Division of Endocrinology, Department of Medicine, Banting & Best Diabetes Centre, University of Toronto, Eaton Building, Room 12E248, 200 Elizabeth St, Toronto, Ontario M5G 2C4, Canada
| | - Alice H Lichtenstein
- Cardiovascular Nutrition, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, 711 Washington St Ste 9, Boston, MA 02111, USA
| | - Philippe Moulin
- Department of Endocrinology, GHE, Hospices Civils de Lyon, CarMeN Laboratory, Inserm UMR 1060, CENS-ELI B, Univ-Lyon1, Lyon 69003, France
| | - Børge G Nordestgaard
- Department of Clinical Biochemistry, Copenhagen General Population Study, Herlev and Gentofte Hospital, Copenhagen University Hospital, Herlev Ringvej 75, Herlev 2730, Denmark.,Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, Copenhagen DK-2200, Denmark
| | - Alan T Remaley
- Lipoprotein Metabolism Section, Translational Vascular Medicine Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, 31 Center Dr Ste 10-7C114, Bethesda, MD 20892, USA
| | - Bart Staels
- Univ. Lille, Inserm, CHU Lille, Institut Pasteur de Lille, U1011-EGID, Lille, France
| | - Erik S G Stroes
- Department of Vascular Medicine, Academic Medical Center, 1541 Kings Hwy, Amsterdam 71103, The Netherlands
| | - Marja-Riitta Taskinen
- Research Programs Unit, Clinical and Molecular Metabolism, University of Helsinki, Helsinki, Finland
| | - Lale S Tokgözoğlu
- Department of Cardiology, Hacettepe University Faculty of Medicine, 06100 Sıhhiye, Ankara, Turkey
| | - Anne Tybjaerg-Hansen
- Department of Clinical Biochemistry, Blegdamsvej 9, Rigshospitalet, Copenhagen 2100, Denmark.,Copenhagen General Population Study, Herlev and Gentofte Hospital, Herlev, Denmark.,Copenhagen City Heart Study, Frederiksberg Hospital, Nordre Fasanvej, Frederiksberg 57 2000, Denmark.,Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej, Copenhagen 3B 2200, Denmark
| | - Jane K Stock
- European Atherosclerosis Society, Mässans Gata 10, Gothenburg SE-412 51, Sweden
| | - Alberico L Catapano
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano and IRCCS MultiMedica, Via Festa del Perdono 7, Milan 20122, Italy
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13
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Montastier É, Ye RZ, Noll C, Bouffard L, Fortin M, Frisch F, Phoenix S, Guérin B, Turcotte ÉE, Lewis GF, Carpentier AC. Increased postprandial nonesterified fatty acid efflux from adipose tissue in prediabetes is offset by enhanced dietary fatty acid adipose trapping. Am J Physiol Endocrinol Metab 2021; 320:E1093-E1106. [PMID: 33870714 DOI: 10.1152/ajpendo.00619.2020] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The mechanism of increased postprandial nonesterified fatty acid (NEFA) appearance in the circulation in impaired glucose tolerance (IGT) is due to increased adipose tissue lipolysis but could also be contributed to by reduced adipose tissue (AT) dietary fatty acid (DFA) trapping and increased "spillover" into the circulation. Thirty-one subjects with IGT (14 women, 17 men) and 29 with normal glucose tolerance (NGT, 15 women, 14 men) underwent a meal test with oral and intravenous palmitate tracers and the oral [18F]-fluoro-thia-heptadecanoic acid positron emission tomography method. Postprandial palmitate appearance (Rapalmitate) was higher in IGT versus NGT (P < 0.001), driven exclusively by Rapalmitate from obesity-associated increase in intracellular lipolysis (P = 0.01), as Rapalmitate from DFA spillover was not different between the groups (P = 0.19) and visceral AT DFA trapping was even higher in IGT versus NGT (P = 0.02). Plasma glycerol appearance was lower in IGT (P = 0.01), driven down by insulin resistance and increased insulin secretion. Thus, we found higher AT DFA trapping, limiting spillover to lean organs and in part offsetting the increase in Rapalmitate from intracellular lipolysis. Whether similar findings occur in frank diabetes, a condition also characterized by insulin resistance but relative insulin deficiency, requires further investigation (Clinicaltrials.gov: NCT04088344, NCT02808182).NEW & NOTEWORTHY We found higher adipose tissue dietary fatty acid trapping, limiting spillover to lean organs, that in part offsets the increase in appearance rate of palmitate from intracellular lipolysis in prediabetes. These results point to the adaptive nature of adipose tissue trapping and dietary fatty acid spillover as a protective mechanism against excess obesity-related palmitate appearance rate from intracellular adipose tissue lipolysis.
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Affiliation(s)
- Émilie Montastier
- Division of Endocrinology, Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Run Zhou Ye
- Division of Endocrinology, Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Christophe Noll
- Division of Endocrinology, Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Lucie Bouffard
- Division of Endocrinology, Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Mélanie Fortin
- Division of Endocrinology, Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Frédérique Frisch
- Division of Endocrinology, Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | | | - Brigitte Guérin
- Department of Radiobiology and Nuclear Medicine, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Éric E Turcotte
- Department of Radiobiology and Nuclear Medicine, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Gary F Lewis
- Division of Endocrinology, Department of Medicine, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - André C Carpentier
- Division of Endocrinology, Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, Canada
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Nahmias A, Stahel P, Tian L, Xiao C, Lewis GF. GLP-1 (Glucagon-Like Peptide-1) Is Physiologically Relevant for Chylomicron Secretion Beyond Its Known Pharmacological Role. Arterioscler Thromb Vasc Biol 2021; 41:1893-1900. [PMID: 33951941 DOI: 10.1161/atvbaha.121.316311] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Avital Nahmias
- Division of Endocrinology, Department of Medicine and Banting and Best Diabetes Centre, University of Toronto, Ontario, Canada (A.N., P.S., L.T., G.F.L.)
| | - Priska Stahel
- Division of Endocrinology, Department of Medicine and Banting and Best Diabetes Centre, University of Toronto, Ontario, Canada (A.N., P.S., L.T., G.F.L.)
| | - Lili Tian
- Division of Endocrinology, Department of Medicine and Banting and Best Diabetes Centre, University of Toronto, Ontario, Canada (A.N., P.S., L.T., G.F.L.)
| | - Changting Xiao
- Department of Anatomy, Physiology and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, Canada (C.X.)
| | - Gary F Lewis
- Division of Endocrinology, Department of Medicine and Banting and Best Diabetes Centre, University of Toronto, Ontario, Canada (A.N., P.S., L.T., G.F.L.)
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15
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Lewis GF, Carpentier AC, Pereira S, Hahn M, Giacca A. Direct and indirect control of hepatic glucose production by insulin. Cell Metab 2021; 33:709-720. [PMID: 33765416 DOI: 10.1016/j.cmet.2021.03.007] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 02/23/2021] [Accepted: 03/05/2021] [Indexed: 01/08/2023]
Abstract
There is general agreement that the acute suppression of hepatic glucose production by insulin is mediated by both a direct and an indirect effect on the liver. There is, however, no consensus regarding the relative magnitude of these effects under physiological conditions. Extensive research over the past three decades in humans and animal models has provided discordant results between these two modes of insulin action. Here, we review the field to make the case that physiologically direct hepatic insulin action dominates acute suppression of glucose production, but that there is also a delayed, second order regulation of this process via extrahepatic effects. We further provide our views regarding the timing, dominance, and physiological relevance of these effects and discuss novel concepts regarding insulin regulation of adipose tissue fatty acid metabolism and central nervous system (CNS) signaling to the liver, as regulators of insulin's extrahepatic effects on glucose production.
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Affiliation(s)
- Gary F Lewis
- Departments of Medicine and Physiology, University of Toronto, Toronto, ON, Canada; Banting & Best Diabetes Centre, University of Toronto, Toronto, ON, Canada; Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada.
| | - Andre C Carpentier
- Division of Endocrinology, Department of Medicine, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Sandra Pereira
- Centre for Addiction and Mental Health and Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Margaret Hahn
- Banting & Best Diabetes Centre, University of Toronto, Toronto, ON, Canada; Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada; Centre for Addiction and Mental Health and Department of Psychiatry, University of Toronto, Toronto, ON, Canada
| | - Adria Giacca
- Departments of Medicine and Physiology, University of Toronto, Toronto, ON, Canada; Banting & Best Diabetes Centre, University of Toronto, Toronto, ON, Canada; Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada
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16
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Nahmias A, Stahel P, Xiao C, Lewis GF. Glycemia and Atherosclerotic Cardiovascular Disease: Exploring the Gap Between Risk Marker and Risk Factor. Front Cardiovasc Med 2020; 7:100. [PMID: 32582769 PMCID: PMC7296136 DOI: 10.3389/fcvm.2020.00100] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 05/11/2020] [Indexed: 01/11/2023] Open
Abstract
There is consistent, unequivocal and reproducible epidemiological evidence derived from diverse populations that various indices of glycemia (fasting plasma glucose, post-prandial or post oral glucose challenge plasma glucose, HbA1c) are associated with an increased risk of atherosclerotic cardiovascular disease (ASCVD), even in the prediabetic state. Furthermore, there is abundant experimental evidence demonstrating that hyperglycemia per se accelerates and aggravates the atherosclerotic process, providing biological plausibility to the concept that hyperglycemia is causally related or a true risk factor for ASCVD. Two studies in particular, DCCT and UKPDS, that enrolled a younger cohort of patients with type 1 diabetes or an older cohort with newly diagnosed type 2 diabetes, respectively, showed trends toward a reduction in ASCVD. The reductions in ASCVD reached statistical significance only after prolonged follow up, and when differences in HbA1c were no longer maintained (referred to by some as a “legacy effect”). More recent studies in those with established type 2 diabetes, in which glycemic control was improved by a variety of strategies, failed to demonstrate reductions in ASCVD. The gap in evidence supporting hyperglycemia as a true causative risk factor for ASCVD or simply a risk marker for some other confounding causative factor is discussed in this review. We conclude that hyperglycemia does appear to be at least partially causative of ASCVD (i.e., an ASCVD risk factor). We discuss how this evidence can be incorporated into an overall therapeutic strategy to prevent ASCVD in those with prediabetes and established diabetes.
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Affiliation(s)
- Avital Nahmias
- Division of Endocrinology, Department of Medicine, Banting & Best Diabetes Centre, University of Toronto, Toronto, ON, Canada
| | - Priska Stahel
- Division of Endocrinology, Department of Medicine, Banting & Best Diabetes Centre, University of Toronto, Toronto, ON, Canada
| | - Changting Xiao
- Division of Endocrinology, Department of Medicine, Banting & Best Diabetes Centre, University of Toronto, Toronto, ON, Canada
| | - Gary F Lewis
- Division of Endocrinology, Department of Medicine, Banting & Best Diabetes Centre, University of Toronto, Toronto, ON, Canada
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17
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MacCallum L, Mathers A, Kellar J, Rousse-Grossman J, Moore J, Lewis GF, Dolovich L. Pharmacists report lack of reinforcement and the work environment as the biggest barriers to routine monitoring and follow-up for people with diabetes: A survey of community pharmacists. Res Social Adm Pharm 2020; 17:332-343. [PMID: 32327399 DOI: 10.1016/j.sapharm.2020.04.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 04/01/2020] [Accepted: 04/04/2020] [Indexed: 10/24/2022]
Abstract
BACKGROUND Medications with lifestyle are the cornerstone of diabetes management and routine monitoring and follow-up are essential to the delivery of quality care. Documented follow-up rates by pharmacists for people with diabetes are low despite good uptake of initial medication assessments in medication review programs. OBJECTIVES Identify the barriers and facilitators to routine monitoring and follow-up for people with diabetes by community pharmacists. METHODS Pharmacists were invited to complete a survey designed using the Theoretical Domains Framework Version 2 TDF (v2) consisting of 39 questions based on the 14 domains of the TDFv2 with quantitative response options using a 7 point Likert scale and 2 open-ended questions. Baseline information about the respondents and their practice sites were summarized using descriptive statistics. Mean scores and standard deviations were calculated for each of the Likert scale responses. Responses to open-ended questions were analyzed and coded using an inductive thematic approach. RESULTS 346 pharmacists completed the survey (4.76% response rate). The TDF domains found to be positively influencing the delivery of routine monitoring and follow-up activities were beliefs about consequences for people with diabetes (6.08 ± 1.13), pharmacist knowledge (5.93 ± 0.99), pharmacist skills (5.44 ± 1.44), social influences (5.36 ± 1.32) and optimism (5.20 ± 1.58). The domains found to be negatively influencing were reinforcement (3.0 ± 1.89) and environmental context and resources (3.30 ± 1.81). Themes emerging from the thematic analysis included time and competing priorities, reimbursement, patient engagement, workflow and human resources, access to labs and clinical information, information technology and support from the owner/manager. CONCLUSIONS Our research concludes that pharmacists report that their knowledge, skills, and beliefs about their role and responsibility, social influences and optimism are positive influences on routine monitoring and follow-up while reinforcement and the environmental context/resources are the greatest negative influences. Strategies to improve follow-up should be focused in these areas.
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Affiliation(s)
- Lori MacCallum
- Banting & Best Diabetes Centre, Faculty of Medicine, University of Toronto, 200 Elizabeth St. 12E 252, Toronto, Ontario, M5G 2C4, Canada; Toronto General Hospital Research Institute, University Health Network, 200 Elizabeth St, Toronto, ON, M5G 2C4, Canada; Leslie Dan Faculty of Pharmacy University of Toronto, 144 College St, Toronto, ON, M5S 3M2, Canada.
| | - Annalise Mathers
- Leslie Dan Faculty of Pharmacy University of Toronto, 144 College St, Toronto, ON, M5S 3M2, Canada
| | - Jamie Kellar
- Leslie Dan Faculty of Pharmacy University of Toronto, 144 College St, Toronto, ON, M5S 3M2, Canada
| | - Jeremy Rousse-Grossman
- Leslie Dan Faculty of Pharmacy University of Toronto, 144 College St, Toronto, ON, M5S 3M2, Canada
| | - Julia Moore
- The Center for Implementation, 20 Northampton Dr., Toronto, ON, M9B 4S6, Canada
| | - Gary F Lewis
- Banting & Best Diabetes Centre, Faculty of Medicine, University of Toronto, 200 Elizabeth St. 12E 252, Toronto, Ontario, M5G 2C4, Canada; Toronto General Hospital Research Institute, University Health Network, 200 Elizabeth St, Toronto, ON, M5G 2C4, Canada
| | - Lisa Dolovich
- Leslie Dan Faculty of Pharmacy University of Toronto, 144 College St, Toronto, ON, M5S 3M2, Canada
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Xiao C, Stahel P, Nahmias A, Lewis GF. Emerging Role of Lymphatics in the Regulation of Intestinal Lipid Mobilization. Front Physiol 2020; 10:1604. [PMID: 32063861 PMCID: PMC7000543 DOI: 10.3389/fphys.2019.01604] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 12/20/2019] [Indexed: 12/21/2022] Open
Abstract
Intestinal handling of dietary triglycerides has important implications for health and disease. Following digestion in the intestinal lumen, absorption, and re-esterification of fatty acids and monoacylglycerols in intestinal enterocytes, triglycerides are packaged into lipoprotein particles (chylomicrons) for secretion or into cytoplasmic lipid droplets for transient or more prolonged storage. Despite the recognition of prolonged retention of triglycerides in the post-absorptive phase and subsequent release from the intestine in chylomicron particles, the underlying regulatory mechanisms remain poorly understood. Chylomicron secretion involves multiple steps, including intracellular assembly and post-assembly transport through cellular organelles, the lamina propria, and the mesenteric lymphatics before being released into the circulation. Contrary to the long-held view that the intestinal lymphatic vasculature acts mainly as a passive conduit, it is increasingly recognized to play an active and regulatory role in the rate of chylomicron release into the circulation. Here, we review the latest advances in understanding the role of lymphatics in intestinal lipid handling and chylomicron secretion. We highlight emerging evidence that oral glucose and the gut hormone glucagon-like peptide-2 mobilize retained enteral lipid by differing mechanisms to promote the secretion of chylomicrons via glucose possibly by mobilizing cytoplasmic lipid droplets and via glucagon-like peptide-2 possibly by targeting post-enterocyte secretory mechanisms. We discuss other potential regulatory factors that are the focus of ongoing and future research. Regulation of lymphatic pumping and function is emerging as an area of great interest in our understanding of the integrated absorption of dietary fat and chylomicron secretion and potential implications for whole-body metabolic health.
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Affiliation(s)
- Changting Xiao
- Department of Medicine and Department of Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, Canada
| | - Priska Stahel
- Department of Medicine and Department of Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, Canada
| | - Avital Nahmias
- Department of Medicine and Department of Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, Canada
| | - Gary F Lewis
- Department of Medicine and Department of Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, Canada
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Abstract
Type 2 diabetes (T2D) is associated with increased risk of cardiovascular disease (CVD). In insulin resistant states such as the metabolic syndrome, overproduction and impaired clearance of liver-derived very-low-density lipoproteins and gut-derived chylomicrons (CMs) contribute to hypertriglyceridemia and elevated atherogenic remnant lipoproteins. Although ingested fat is the major stimulus of CM secretion, intestinal lipid handling and ultimately CM secretory rate is determined by numerous additional regulatory inputs including nutrients, hormones and neural signals that fine tune CM secretion during fasted and fed states. Insulin resistance and T2D represent perturbed metabolic states in which intestinal sensitivity to key regulatory hormones such as insulin, leptin and glucagon-like peptide-1 (GLP-1) may be altered, contributing to increased CM secretion. In this review, we describe the evidence from human and animal models demonstrating increased CM secretion in insulin resistance and T2D and discuss the molecular mechanisms underlying these effects. Several novel compounds are in various stages of preclinical and clinical investigation to modulate intestinal CM synthesis and secretion. Their efficacy, safety and therapeutic utility are discussed. Similarly, the effects of currently approved lipid modulating therapies such as statins, ezetimibe, fibrates, and PCSK9 inhibitors on intestinal CM production are discussed. The intricacies of intestinal CM production are an active area of research that may yield novel therapies to prevent atherosclerotic CVD in insulin resistance and T2D.
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20
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Garg A, Garg V, Hegele RA, Lewis GF. Practical definitions of severe versus familial hypercholesterolaemia and hypertriglyceridaemia for adult clinical practice. Lancet Diabetes Endocrinol 2019; 7:880-886. [PMID: 31445954 DOI: 10.1016/s2213-8587(19)30156-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 04/08/2019] [Accepted: 04/09/2019] [Indexed: 12/20/2022]
Abstract
Diagnostic scoring systems for familial hypercholesterolaemia and familial chylomicronaemia syndrome often cannot differentiate between adults who have extreme dyslipidaemia based on a simple monogenic cause versus people with a more complex cause involving polygenic factors and an environmental component. This more complex group of patients carries a substantial risk of atherosclerotic cardiovascular disease in the case of marked hypercholesterolaemia and pancreatitis in the case of marked hypertriglyceridaemia. Complications are mainly a function of the degree of disturbance in lipid metabolism resulting in elevated lipid levels, so the added value of knowing the precise genetic cause in clinical decision making is unclear and does not lead to clinically meaningful benefit. We propose that for severe elevations of plasma low density lipoprotein cholesterol or triglyceride, the primary factor driving intervention should be the biochemical perturbation rather than the clinical risk score. This underscores the importance of expanding the definition of severe dyslipidaemias and to not rely solely on clinical scoring systems to identify individuals who would benefit from appropriate treatment approaches. We advocate for the use of simple, practical, clinical, and largely biochemically based definitions for severe hypercholesterolaemia (eg, LDL cholesterol >5 mmol/L) and severe hypertriglyceridaemia (triglyceride >10 mmol/L), which complement current definitions of familial hypercholesterolaemia and familial chylomicronaemia syndrome. Irrespective of the precise genetic cause, individuals diagnosed with severe hypercholesterolaemia and severe hypertriglyceridaemia require intensive therapy, including special consideration for new effective but more expensive therapies.
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Affiliation(s)
- Ankit Garg
- Departments of Medicine and Physiology, Division of Endocrinology and Metabolism, Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, Canada
| | - Vinay Garg
- Departments of Medicine and Physiology, Division of Endocrinology and Metabolism, Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, Canada
| | - Robert A Hegele
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - Gary F Lewis
- Departments of Medicine and Physiology, Division of Endocrinology and Metabolism, Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, Canada.
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Xiao C, Stahel P, Morgantini C, Nahmias A, Dash S, Lewis GF. Glucagon-like peptide-2 mobilizes lipids from the intestine by a systemic nitric oxide-independent mechanism. Diabetes Obes Metab 2019; 21:2535-2541. [PMID: 31364232 DOI: 10.1111/dom.13839] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 07/09/2019] [Accepted: 07/25/2019] [Indexed: 12/20/2022]
Abstract
AIM To test the hypothesis that gut hormone glucagon-like peptide-2 (GLP-2) mobilizes intestinal triglyceride (TG) stores and stimulates chylomicron secretion by a nitric oxide (NO)-dependent mechanism in humans. METHODS In a randomized, single-blind, cross-over study, 10 healthy male volunteers ingested a high-fat formula followed, 7 hours later, by one of three treatments: NO synthase inhibitor L-NG -monomethyl arginine acetate (L-NMMA) + GLP-2 analogue teduglutide, normal saline + teduglutide, or L-NMMA + placebo. TG in plasma and lipoprotein fractions were measured, along with measurement of blood flow in superior mesenteric and coeliac arteries using Doppler ultrasound in six participants. RESULTS Teduglutide rapidly increased mesenteric blood flow and TG concentrations in plasma, in TG-rich lipoproteins, and most robustly in chylomicrons. L-NMMA significantly attenuated teduglutide-induced enhancement of mesenteric blood flow but not TG mobilization and chylomicron secretion. CONCLUSIONS GLP-2 mobilization of TG stores and stimulation of chylomicron secretion from the small intestine appears to be independent of systemic NO in humans.
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Affiliation(s)
- Changting Xiao
- Department of Medicine and Department of Physiology, Division of Endocrinology and Metabolism, Banting and Best Diabetes Centre, University of Toronto, Toronto, Canada
| | - Priska Stahel
- Department of Medicine and Department of Physiology, Division of Endocrinology and Metabolism, Banting and Best Diabetes Centre, University of Toronto, Toronto, Canada
| | - Cecilia Morgantini
- Department of Medicine and Department of Physiology, Division of Endocrinology and Metabolism, Banting and Best Diabetes Centre, University of Toronto, Toronto, Canada
| | - Avital Nahmias
- Department of Medicine and Department of Physiology, Division of Endocrinology and Metabolism, Banting and Best Diabetes Centre, University of Toronto, Toronto, Canada
| | - Satya Dash
- Department of Medicine and Department of Physiology, Division of Endocrinology and Metabolism, Banting and Best Diabetes Centre, University of Toronto, Toronto, Canada
| | - Gary F Lewis
- Department of Medicine and Department of Physiology, Division of Endocrinology and Metabolism, Banting and Best Diabetes Centre, University of Toronto, Toronto, Canada
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Stahel P, Xiao C, Davis X, Tso P, Lewis GF. Glucose and GLP-2 (Glucagon-Like Peptide-2) Mobilize Intestinal Triglyceride by Distinct Mechanisms. Arterioscler Thromb Vasc Biol 2019; 39:1565-1573. [PMID: 31294621 DOI: 10.1161/atvbaha.119.313011] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
OBJECTIVE Dietary triglycerides are partially retained in the intestine within intracellular or extracellular compartments, which can be rapidly mobilized in response to several stimuli, including glucose and GLP-2 (glucagon-like peptide-2). To elucidate the mechanism of intestinal lipid mobilization, this study examined the patterns and time course of lymph flow and triglycerides after glucose and GLP-2 treatment in rats. Approach and Results: Lymph flow, triglyceride concentration, and triglyceride output were assessed in mesenteric lymph duct-cannulated rats in response to an intraduodenal (i.d.) lipid bolus followed 5 hours later by either (1) i.d. saline+intraperitoneal (i.p.) saline (placebo), (2) i.d. glucose plus i.p. saline, (3) i.d. saline+i.p. GLP-2, or (4) i.d. glucose+i.p. GLP-2. GLP-2 and glucose administered alone or in combination stimulated total triglyceride output to a similar extent, but the timing and pattern of stimulation differed markedly. Whereas GLP-2 rapidly increased lymph flow with no effect on lymph triglyceride concentration or triglyceride:apoB48 (apolipoprotein B48) ratio (a surrogate marker of chylomicron size) compared with placebo, glucose transiently decreased lymph flow followed by delayed stimulation of lymph flow and increased lymph triglyceride concentration and triglyceride:apoB48 ratio. CONCLUSIONS Glucose and GLP-2 robustly enhanced intestinal triglyceride output in rats but with different effects on lymph flow, lymph triglyceride concentration, and chylomicron size. GLP-2 stimulated triglyceride output primarily by enhancing lymph flow with no effect on chylomicron size, whereas glucose mobilized intestinal triglycerides, stimulating secretion of larger chylomicrons. This suggests that these 2 stimuli mobilize intestinal lipid by different mechanisms.
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Affiliation(s)
- Priska Stahel
- From the Division of Endocrinology and Metabolism, Department of Medicine and Physiology, Banting & Best Diabetes Centre, University of Toronto, ON, Canada (P.S., C.X., G.F.L.)
| | - Changting Xiao
- From the Division of Endocrinology and Metabolism, Department of Medicine and Physiology, Banting & Best Diabetes Centre, University of Toronto, ON, Canada (P.S., C.X., G.F.L.)
| | - Xenia Davis
- Department of Pathology and Laboratory Medicine, University of Cincinnati, OH (X.D., P.T.)
| | - Patrick Tso
- Department of Pathology and Laboratory Medicine, University of Cincinnati, OH (X.D., P.T.)
| | - Gary F Lewis
- From the Division of Endocrinology and Metabolism, Department of Medicine and Physiology, Banting & Best Diabetes Centre, University of Toronto, ON, Canada (P.S., C.X., G.F.L.)
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Affiliation(s)
- Changting Xiao
- Department of Medicine, University of Toronto, Toronto, ON, Canada2Department of Physiology, University of Toronto, Toronto, ON, Canada3Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, Canada
| | - Robert A Hegele
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - Gary F Lewis
- Department of Medicine, University of Toronto, Toronto, ON, Canada2Department of Physiology, University of Toronto, Toronto, ON, Canada3Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, Canada
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Abbott TMC, Alarcon A, Allam S, Andersen P, Andrade-Oliveira F, Annis J, Asorey J, Avila S, Bacon D, Banik N, Bassett BA, Baxter E, Bechtol K, Becker MR, Bernstein GM, Bertin E, Blazek J, Bridle SL, Brooks D, Brout D, Burke DL, Calcino J, Camacho H, Campos A, Carnero Rosell A, Carollo D, Carrasco Kind M, Carretero J, Castander FJ, Cawthon R, Challis P, Chan KC, Chang C, Childress M, Crocce M, Cunha CE, D'Andrea CB, da Costa LN, Davis C, Davis TM, De Vicente J, DePoy DL, DeRose J, Desai S, Diehl HT, Dietrich JP, Dodelson S, Doel P, Drlica-Wagner A, Eifler TF, Elvin-Poole J, Estrada J, Evrard AE, Fernandez E, Flaugher B, Foley RJ, Fosalba P, Frieman J, Galbany L, García-Bellido J, Gatti M, Gaztanaga E, Gerdes DW, Giannantonio T, Glazebrook K, Goldstein DA, Gruen D, Gruendl RA, Gschwend J, Gutierrez G, Hartley WG, Hinton SR, Hollowood DL, Honscheid K, Hoormann JK, Hoyle B, Huterer D, Jain B, James DJ, Jarvis M, Jeltema T, Kasai E, Kent S, Kessler R, Kim AG, Kokron N, Krause E, Kron R, Kuehn K, Kuropatkin N, Lahav O, Lasker J, Lemos P, Lewis GF, Li TS, Lidman C, Lima M, Lin H, Macaulay E, MacCrann N, Maia MAG, March M, Marriner J, Marshall JL, Martini P, McMahon RG, Melchior P, Menanteau F, Miquel R, Mohr JJ, Morganson E, Muir J, Möller A, Neilsen E, Nichol RC, Nord B, Ogando RLC, Palmese A, Pan YC, Peiris HV, Percival WJ, Plazas AA, Porredon A, Prat J, Romer AK, Roodman A, Rosenfeld R, Ross AJ, Rykoff ES, Samuroff S, Sánchez C, Sanchez E, Scarpine V, Schindler R, Schubnell M, Scolnic D, Secco LF, Serrano S, Sevilla-Noarbe I, Sharp R, Sheldon E, Smith M, Soares-Santos M, Sobreira F, Sommer NE, Swann E, Swanson MEC, Tarle G, Thomas D, Thomas RC, Troxel MA, Tucker BE, Uddin SA, Vielzeuf P, Walker AR, Wang M, Weaverdyck N, Wechsler RH, Weller J, Yanny B, Zhang B, Zhang Y, Zuntz J. Cosmological Constraints from Multiple Probes in the Dark Energy Survey. Phys Rev Lett 2019; 122:171301. [PMID: 31107093 DOI: 10.1103/physrevlett.122.171301] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 02/19/2019] [Indexed: 06/09/2023]
Abstract
The combination of multiple observational probes has long been advocated as a powerful technique to constrain cosmological parameters, in particular dark energy. The Dark Energy Survey has measured 207 spectroscopically confirmed type Ia supernova light curves, the baryon acoustic oscillation feature, weak gravitational lensing, and galaxy clustering. Here we present combined results from these probes, deriving constraints on the equation of state, w, of dark energy and its energy density in the Universe. Independently of other experiments, such as those that measure the cosmic microwave background, the probes from this single photometric survey rule out a Universe with no dark energy, finding w=-0.80_{-0.11}^{+0.09}. The geometry is shown to be consistent with a spatially flat Universe, and we obtain a constraint on the baryon density of Ω_{b}=0.069_{-0.012}^{+0.009} that is independent of early Universe measurements. These results demonstrate the potential power of large multiprobe photometric surveys and pave the way for order of magnitude advances in our constraints on properties of dark energy and cosmology over the next decade.
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Affiliation(s)
- T M C Abbott
- Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, Casilla 603, La Serena, Chile
| | - A Alarcon
- Institut d'Estudis Espacials de Catalunya (IEEC), 08034 Barcelona, Spain
- Institute of Space Sciences (ICE, CSIC), Campus UAB, Carrer de Can Magrans, s/n, 08193 Barcelona, Spain
| | - S Allam
- Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, Illinois 60510, USA
| | - P Andersen
- School of Mathematics and Physics, University of Queensland, Brisbane, QLD 4072, Australia
- University of Copenhagen, Dark Cosmology Centre, Juliane Maries Vej 30, 2100 Copenhagen O, Denmark
| | - F Andrade-Oliveira
- Instituto de Física Teórica, Universidade Estadual Paulista, São Paulo, Brazil
- Laboratório Interinstitucional de e-Astronomia-LIneA, Rua Gal. José Cristino 77, Rio de Janeiro, RJ 20921-400, Brazil
| | - J Annis
- Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, Illinois 60510, USA
| | - J Asorey
- Korea Astronomy and Space Science Institute, Yuseong-gu, Daejeon 305-348, Korea
| | - S Avila
- Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 3FX, United Kingdom
| | - D Bacon
- Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 3FX, United Kingdom
| | - N Banik
- Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, Illinois 60510, USA
| | - B A Bassett
- African Institute for Mathematical Sciences, 6 Melrose Road, Muizenberg 7945, South Africa
- South African Astronomical Observatory, P.O.Box 9, Observatory 7935, South Africa
| | - E Baxter
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - K Bechtol
- LSST, 933 North Cherry Avenue, Tucson, Arizona 85721, USA
- Physics Department, 2320 Chamberlin Hall, University of Wisconsin-Madison, 1150 University Avenue Madison, Wisconsin 53706-1390, USA
| | - M R Becker
- Argonne National Laboratory, 9700 South Cass Avenue, Lemont, Illinois 60439, USA
| | - G M Bernstein
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - E Bertin
- CNRS, UMR 7095, Institut d'Astrophysique de Paris, F-75014 Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, UMR 7095, Institut d'Astrophysique de Paris, F-75014 Paris, France
| | - J Blazek
- Center for Cosmology and Astro-Particle Physics, The Ohio State University, Columbus, Ohio 43210, USA
- Institute of Physics, Laboratory of Astrophysics, École Polytechnique Fédérale de Lausanne (EPFL), Observatoire de Sauverny, 1290 Versoix, Switzerland
| | - S L Bridle
- Jodrell Bank Center for Astrophysics, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom
| | - D Brooks
- Department of Physics & Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - D Brout
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - D L Burke
- Kavli Institute for Particle Astrophysics & Cosmology, P. O. Box 2450, Stanford University, Stanford, California 94305, USA
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - J Calcino
- School of Mathematics and Physics, University of Queensland, Brisbane, QLD 4072, Australia
| | - H Camacho
- Laboratório Interinstitucional de e-Astronomia-LIneA, Rua Gal. José Cristino 77, Rio de Janeiro, RJ 20921-400, Brazil
- Departamento de Física Matemática, Instituto de Física, Universidade de São Paulo, CP 66318, São Paulo, SP 05314-970, Brazil
| | - A Campos
- Instituto de Física Teórica, Universidade Estadual Paulista, São Paulo, Brazil
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15312, USA
| | - A Carnero Rosell
- Laboratório Interinstitucional de e-Astronomia-LIneA, Rua Gal. José Cristino 77, Rio de Janeiro, RJ 20921-400, Brazil
- Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain
| | - D Carollo
- INAF, Astrophysical Observatory of Turin, I-10025 Pino Torinese, Italy
| | - M Carrasco Kind
- Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 W. Green Street, Urbana, Illinois 61801, USA
- National Center for Supercomputing Applications, 1205 West Clark St., Urbana, Illinois 61801, USA
| | - J Carretero
- Institut de Física d'Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Campus UAB, 08193 Bellaterra (Barcelona) Spain
| | - F J Castander
- Institut d'Estudis Espacials de Catalunya (IEEC), 08034 Barcelona, Spain
- Institute of Space Sciences (ICE, CSIC), Campus UAB, Carrer de Can Magrans, s/n, 08193 Barcelona, Spain
| | - R Cawthon
- Physics Department, 2320 Chamberlin Hall, University of Wisconsin-Madison, 1150 University Avenue Madison, Wisconsin 53706-1390, USA
| | - P Challis
- Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, Massachusetts 02138, USA
| | - K C Chan
- Institut d'Estudis Espacials de Catalunya (IEEC), 08034 Barcelona, Spain
- Institute of Space Sciences (ICE, CSIC), Campus UAB, Carrer de Can Magrans, s/n, 08193 Barcelona, Spain
| | - C Chang
- Department of Astronomy and Astrophysics, University of Chicago, Chicago, Illinois 60637, USA
- Kavli Institute for Cosmological Physics, University of Chicago, Chicago, Illinois 60637, USA
| | - M Childress
- School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - M Crocce
- Institut d'Estudis Espacials de Catalunya (IEEC), 08034 Barcelona, Spain
- Institute of Space Sciences (ICE, CSIC), Campus UAB, Carrer de Can Magrans, s/n, 08193 Barcelona, Spain
| | - C E Cunha
- Kavli Institute for Particle Astrophysics & Cosmology, P. O. Box 2450, Stanford University, Stanford, California 94305, USA
| | - C B D'Andrea
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - L N da Costa
- Laboratório Interinstitucional de e-Astronomia-LIneA, Rua Gal. José Cristino 77, Rio de Janeiro, RJ 20921-400, Brazil
- Observatório Nacional, Rua Gal. José Cristino 77, Rio de Janeiro, RJ 20921-400, Brazil
| | - C Davis
- Kavli Institute for Particle Astrophysics & Cosmology, P. O. Box 2450, Stanford University, Stanford, California 94305, USA
| | - T M Davis
- School of Mathematics and Physics, University of Queensland, Brisbane, QLD 4072, Australia
| | - J De Vicente
- Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain
| | - D L DePoy
- George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, and Department of Physics and Astronomy, Texas A&M University, College Station, Texas 77843, USA
| | - J DeRose
- Kavli Institute for Particle Astrophysics & Cosmology, P. O. Box 2450, Stanford University, Stanford, California 94305, USA
- Department of Physics, Stanford University, 382 Via Pueblo Mall, Stanford, California 94305, USA
| | - S Desai
- Department of Physics, IIT Hyderabad, Kandi, Telangana 502285, India
| | - H T Diehl
- Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, Illinois 60510, USA
| | - J P Dietrich
- Excellence Cluster Universe, Boltzmannstr. 2, 85748 Garching, Germany
- Faculty of Physics, Ludwig-Maximilians-Universität, Scheinerstr. 1, 81679 Munich, Germany
| | - S Dodelson
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15312, USA
| | - P Doel
- Department of Physics & Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - A Drlica-Wagner
- Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, Illinois 60510, USA
- Kavli Institute for Cosmological Physics, University of Chicago, Chicago, Illinois 60637, USA
| | - T F Eifler
- Department of Astronomy/Steward Observatory, 933 North Cherry Avenue, Tucson, Arizona 85721-0065, USA
- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, California 91109, USA
| | - J Elvin-Poole
- Center for Cosmology and Astro-Particle Physics, The Ohio State University, Columbus, Ohio 43210, USA
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
| | - J Estrada
- Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, Illinois 60510, USA
| | - A E Evrard
- Department of Astronomy, University of Michigan, Ann Arbor, Michigan 48109, USA
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - E Fernandez
- Institut de Física d'Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Campus UAB, 08193 Bellaterra (Barcelona) Spain
| | - B Flaugher
- Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, Illinois 60510, USA
| | - R J Foley
- Santa Cruz Institute for Particle Physics, Santa Cruz, California 95064, USA
| | - P Fosalba
- Institut d'Estudis Espacials de Catalunya (IEEC), 08034 Barcelona, Spain
- Institute of Space Sciences (ICE, CSIC), Campus UAB, Carrer de Can Magrans, s/n, 08193 Barcelona, Spain
| | - J Frieman
- Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, Illinois 60510, USA
- Kavli Institute for Cosmological Physics, University of Chicago, Chicago, Illinois 60637, USA
| | - L Galbany
- PITT PACC, Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - J García-Bellido
- Instituto de Fisica Teorica UAM/CSIC, Universidad Autonoma de Madrid, 28049 Madrid, Spain
| | - M Gatti
- Institut de Física d'Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Campus UAB, 08193 Bellaterra (Barcelona) Spain
| | - E Gaztanaga
- Institut d'Estudis Espacials de Catalunya (IEEC), 08034 Barcelona, Spain
- Institute of Space Sciences (ICE, CSIC), Campus UAB, Carrer de Can Magrans, s/n, 08193 Barcelona, Spain
| | - D W Gerdes
- Department of Astronomy, University of Michigan, Ann Arbor, Michigan 48109, USA
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - T Giannantonio
- Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, United Kingdom
- Kavli Institute for Cosmology, University of Cambridge, Madingley Road, Cambridge CB3 0HA, United Kindom
- Universitäts-Sternwarte, Fakultät für Physik, Ludwig-Maximilians Universität München, Scheinerstr. 1, 81679 München, Germany
| | - K Glazebrook
- Centre for Astrophysics & Supercomputing, Swinburne University of Technology, VIC 3122, Australia
| | - D A Goldstein
- California Institute of Technology, 1200 East California Blvd, MC 249-17, Pasadena, California 91125, USA
| | - D Gruen
- Kavli Institute for Particle Astrophysics & Cosmology, P. O. Box 2450, Stanford University, Stanford, California 94305, USA
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Physics, Stanford University, 382 Via Pueblo Mall, Stanford, California 94305, USA
| | - R A Gruendl
- Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 W. Green Street, Urbana, Illinois 61801, USA
- National Center for Supercomputing Applications, 1205 West Clark St., Urbana, Illinois 61801, USA
| | - J Gschwend
- Laboratório Interinstitucional de e-Astronomia-LIneA, Rua Gal. José Cristino 77, Rio de Janeiro, RJ 20921-400, Brazil
- Observatório Nacional, Rua Gal. José Cristino 77, Rio de Janeiro, RJ 20921-400, Brazil
| | - G Gutierrez
- Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, Illinois 60510, USA
| | - W G Hartley
- Department of Physics & Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
- Department of Physics, ETH Zurich, Wolfgang-Pauli-Strasse 16, CH-8093 Zurich, Switzerland
| | - S R Hinton
- School of Mathematics and Physics, University of Queensland, Brisbane, QLD 4072, Australia
| | - D L Hollowood
- Santa Cruz Institute for Particle Physics, Santa Cruz, California 95064, USA
| | - K Honscheid
- Center for Cosmology and Astro-Particle Physics, The Ohio State University, Columbus, Ohio 43210, USA
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
| | - J K Hoormann
- School of Mathematics and Physics, University of Queensland, Brisbane, QLD 4072, Australia
| | - B Hoyle
- Universitäts-Sternwarte, Fakultät für Physik, Ludwig-Maximilians Universität München, Scheinerstr. 1, 81679 München, Germany
- Max Planck Institute for Extraterrestrial Physics, Giessenbachstrasse, 85748 Garching, Germany
| | - D Huterer
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - B Jain
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - D J James
- Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA
| | - M Jarvis
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - T Jeltema
- Santa Cruz Institute for Particle Physics, Santa Cruz, California 95064, USA
| | - E Kasai
- South African Astronomical Observatory, P.O.Box 9, Observatory 7935, South Africa
- Department of Physics, University of Namibia, 340 Mandume Ndemufayo Avenue, Pionierspark, Windhoek, Namibia
| | - S Kent
- Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, Illinois 60510, USA
- Kavli Institute for Cosmological Physics, University of Chicago, Chicago, Illinois 60637, USA
| | - R Kessler
- Department of Astronomy and Astrophysics, University of Chicago, Chicago, Illinois 60637, USA
- Kavli Institute for Cosmological Physics, University of Chicago, Chicago, Illinois 60637, USA
| | - A G Kim
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
| | - N Kokron
- Kavli Institute for Particle Astrophysics & Cosmology, P. O. Box 2450, Stanford University, Stanford, California 94305, USA
- Department of Physics, Stanford University, 382 Via Pueblo Mall, Stanford, California 94305, USA
| | - E Krause
- Department of Astronomy/Steward Observatory, 933 North Cherry Avenue, Tucson, Arizona 85721-0065, USA
| | - R Kron
- Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, Illinois 60510, USA
- Kavli Institute for Cosmological Physics, University of Chicago, Chicago, Illinois 60637, USA
| | - K Kuehn
- Australian Astronomical Optics, Macquarie University, North Ryde, NSW 2113, Australia
| | - N Kuropatkin
- Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, Illinois 60510, USA
| | - O Lahav
- Department of Physics & Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - J Lasker
- Department of Astronomy and Astrophysics, University of Chicago, Chicago, Illinois 60637, USA
- Kavli Institute for Cosmological Physics, University of Chicago, Chicago, Illinois 60637, USA
| | - P Lemos
- Department of Physics & Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
- Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, United Kingdom
- Kavli Institute for Cosmology, University of Cambridge, Madingley Road, Cambridge CB3 0HA, United Kindom
| | - G F Lewis
- Sydney Institute for Astronomy, School of Physics, A28, The University of Sydney, NSW 2006, Australia
| | - T S Li
- Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, Illinois 60510, USA
- Kavli Institute for Cosmological Physics, University of Chicago, Chicago, Illinois 60637, USA
| | - C Lidman
- The Research School of Astronomy and Astrophysics, Australian National University, ACT 2601, Australia
| | - M Lima
- Laboratório Interinstitucional de e-Astronomia-LIneA, Rua Gal. José Cristino 77, Rio de Janeiro, RJ 20921-400, Brazil
- Departamento de Física Matemática, Instituto de Física, Universidade de São Paulo, CP 66318, São Paulo, SP 05314-970, Brazil
| | - H Lin
- Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, Illinois 60510, USA
| | - E Macaulay
- Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 3FX, United Kingdom
| | - N MacCrann
- Center for Cosmology and Astro-Particle Physics, The Ohio State University, Columbus, Ohio 43210, USA
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
| | - M A G Maia
- Laboratório Interinstitucional de e-Astronomia-LIneA, Rua Gal. José Cristino 77, Rio de Janeiro, RJ 20921-400, Brazil
- Observatório Nacional, Rua Gal. José Cristino 77, Rio de Janeiro, RJ 20921-400, Brazil
| | - M March
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - J Marriner
- Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, Illinois 60510, USA
| | - J L Marshall
- George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, and Department of Physics and Astronomy, Texas A&M University, College Station, Texas 77843, USA
| | - P Martini
- Center for Cosmology and Astro-Particle Physics, The Ohio State University, Columbus, Ohio 43210, USA
- Department of Astronomy, The Ohio State University, Columbus, Ohio 43210, USA
| | - R G McMahon
- Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, United Kingdom
- Kavli Institute for Cosmology, University of Cambridge, Madingley Road, Cambridge CB3 0HA, United Kindom
| | - P Melchior
- Department of Astrophysical Sciences, Princeton University, Peyton Hall, Princeton, New Jersey 08544, USA
| | - F Menanteau
- Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 W. Green Street, Urbana, Illinois 61801, USA
- National Center for Supercomputing Applications, 1205 West Clark St., Urbana, Illinois 61801, USA
| | - R Miquel
- Institut de Física d'Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Campus UAB, 08193 Bellaterra (Barcelona) Spain
- Institució Catalana de Recerca i Estudis Avançats, E-08010 Barcelona, Spain
| | - J J Mohr
- Excellence Cluster Universe, Boltzmannstr. 2, 85748 Garching, Germany
- Faculty of Physics, Ludwig-Maximilians-Universität, Scheinerstr. 1, 81679 Munich, Germany
- Max Planck Institute for Extraterrestrial Physics, Giessenbachstrasse, 85748 Garching, Germany
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- National Center for Supercomputing Applications, 1205 West Clark St., Urbana, Illinois 61801, USA
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- Kavli Institute for Particle Astrophysics & Cosmology, P. O. Box 2450, Stanford University, Stanford, California 94305, USA
| | - A Möller
- The Research School of Astronomy and Astrophysics, Australian National University, ACT 2601, Australia
- ARC Centre of Excellence for All-sky Astrophysics (CAASTRO), Millers Point, NSW 2000, Australia
| | - E Neilsen
- Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, Illinois 60510, USA
| | - R C Nichol
- Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 3FX, United Kingdom
| | - B Nord
- Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, Illinois 60510, USA
| | - R L C Ogando
- Laboratório Interinstitucional de e-Astronomia-LIneA, Rua Gal. José Cristino 77, Rio de Janeiro, RJ 20921-400, Brazil
- Observatório Nacional, Rua Gal. José Cristino 77, Rio de Janeiro, RJ 20921-400, Brazil
| | - A Palmese
- Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, Illinois 60510, USA
| | - Y-C Pan
- Division of Theoretical Astronomy, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
- Institute of Astronomy and Astrophysics, Academia Sinica, Taipei 10617, Taiwan
| | - H V Peiris
- Department of Physics & Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - W J Percival
- Department of Physics and Astronomy, University of Waterloo, 200 University Ave W, Waterloo, Ontario N2L 3G1, Canada
- Perimeter Institute for Theoretical Physics, 31 Caroline St. North, Waterloo, Ontario N2L 2Y5, Canada
| | - A A Plazas
- Department of Astrophysical Sciences, Princeton University, Peyton Hall, Princeton, New Jersey 08544, USA
| | - A Porredon
- Institut d'Estudis Espacials de Catalunya (IEEC), 08034 Barcelona, Spain
- Institute of Space Sciences (ICE, CSIC), Campus UAB, Carrer de Can Magrans, s/n, 08193 Barcelona, Spain
| | - J Prat
- Institut de Física d'Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Campus UAB, 08193 Bellaterra (Barcelona) Spain
| | - A K Romer
- Department of Physics and Astronomy, Pevensey Building, University of Sussex, Brighton BN1 9QH, United Kingdom
| | - A Roodman
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- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - R Rosenfeld
- Laboratório Interinstitucional de e-Astronomia-LIneA, Rua Gal. José Cristino 77, Rio de Janeiro, RJ 20921-400, Brazil
- ICTP South American Institute for Fundamental Research Instituto de Física Teórica, Universidade Estadual Paulista, São Paulo, Brazil
| | - A J Ross
- Center for Cosmology and Astro-Particle Physics, The Ohio State University, Columbus, Ohio 43210, USA
| | - E S Rykoff
- Kavli Institute for Particle Astrophysics & Cosmology, P. O. Box 2450, Stanford University, Stanford, California 94305, USA
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - S Samuroff
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15312, USA
| | - C Sánchez
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - E Sanchez
- Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain
| | - V Scarpine
- Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, Illinois 60510, USA
| | - R Schindler
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - M Schubnell
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - D Scolnic
- Department of Physics, Duke University, Durham, North Carolina 27708, USA
| | - L F Secco
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - S Serrano
- Institut d'Estudis Espacials de Catalunya (IEEC), 08034 Barcelona, Spain
- Institute of Space Sciences (ICE, CSIC), Campus UAB, Carrer de Can Magrans, s/n, 08193 Barcelona, Spain
| | - I Sevilla-Noarbe
- Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain
| | - R Sharp
- The Research School of Astronomy and Astrophysics, Australian National University, ACT 2601, Australia
| | - E Sheldon
- Brookhaven National Laboratory, Bldg 510, Upton, New York 11973, USA
| | - M Smith
- School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - M Soares-Santos
- Brandeis University, Physics Department, 415 South Street, Waltham, Massachusetts 02453, USA
| | - F Sobreira
- Laboratório Interinstitucional de e-Astronomia-LIneA, Rua Gal. José Cristino 77, Rio de Janeiro, RJ 20921-400, Brazil
- Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, 13083-859 Campinas, SP, Brazil
| | - N E Sommer
- The Research School of Astronomy and Astrophysics, Australian National University, ACT 2601, Australia
- ARC Centre of Excellence for All-sky Astrophysics (CAASTRO), Millers Point, NSW 2000, Australia
| | - E Swann
- Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 3FX, United Kingdom
| | - M E C Swanson
- National Center for Supercomputing Applications, 1205 West Clark St., Urbana, Illinois 61801, USA
| | - G Tarle
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - D Thomas
- Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 3FX, United Kingdom
| | - R C Thomas
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
| | - M A Troxel
- Department of Physics, Duke University, Durham, North Carolina 27708, USA
| | - B E Tucker
- The Research School of Astronomy and Astrophysics, Australian National University, ACT 2601, Australia
- ARC Centre of Excellence for All-sky Astrophysics (CAASTRO), Millers Point, NSW 2000, Australia
| | - S A Uddin
- Observatories of the Carnegie Institution for Science, 813 Santa Barbara St., Pasadena, California 91101, USA
| | - P Vielzeuf
- Institut de Física d'Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Campus UAB, 08193 Bellaterra (Barcelona) Spain
| | - A R Walker
- Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, Casilla 603, La Serena, Chile
| | - M Wang
- Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, Illinois 60510, USA
| | - N Weaverdyck
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - R H Wechsler
- Kavli Institute for Particle Astrophysics & Cosmology, P. O. Box 2450, Stanford University, Stanford, California 94305, USA
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Physics, Stanford University, 382 Via Pueblo Mall, Stanford, California 94305, USA
| | - J Weller
- Excellence Cluster Universe, Boltzmannstr. 2, 85748 Garching, Germany
- Universitäts-Sternwarte, Fakultät für Physik, Ludwig-Maximilians Universität München, Scheinerstr. 1, 81679 München, Germany
- Max Planck Institute for Extraterrestrial Physics, Giessenbachstrasse, 85748 Garching, Germany
| | - B Yanny
- Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, Illinois 60510, USA
| | - B Zhang
- The Research School of Astronomy and Astrophysics, Australian National University, ACT 2601, Australia
- ARC Centre of Excellence for All-sky Astrophysics (CAASTRO), Millers Point, NSW 2000, Australia
| | - Y Zhang
- Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, Illinois 60510, USA
| | - J Zuntz
- Institute for Astronomy, University of Edinburgh, Edinburgh EH9 3HJ, United Kingdom
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Xiao C, Stahel P, Lewis GF. Regulation of Chylomicron Secretion: Focus on Post-Assembly Mechanisms. Cell Mol Gastroenterol Hepatol 2018; 7:487-501. [PMID: 30819663 PMCID: PMC6396431 DOI: 10.1016/j.jcmgh.2018.10.015] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 10/23/2018] [Accepted: 10/25/2018] [Indexed: 02/06/2023]
Abstract
Rapid and efficient digestion and absorption of dietary triglycerides and other lipids by the intestine, the packaging of those lipids into lipoprotein chylomicron (CM) particles, and their secretion via the lymphatic duct into the blood circulation are essential in maintaining whole-body lipid and energy homeostasis. Biosynthesis and assembly of CMs in enterocytes is a complex multistep process that is subject to regulation by intracellular signaling pathways as well as by hormones, nutrients, and neural factors extrinsic to the enterocyte. Dysregulation of this process has implications for health and disease, contributing to dyslipidemia and a potentially increased risk of atherosclerotic cardiovascular disease. There is increasing recognition that, besides intracellular regulation of CM assembly and secretion, regulation of postassembly pathways also plays important roles in CM secretion. This review examines recent advances in our understanding of the regulation of CM secretion in relation to mobilization of intestinal lipid stores, drawing particular attention to post-assembly regulatory mechanisms, including intracellular trafficking of triglycerides in enterocytes, CM mobilization from the lamina propria, and regulated transport of CM by intestinal lymphatics.
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Affiliation(s)
- Changting Xiao
- Changting Xiao, PhD, Princess Margaret Cancer Research Tower 10-203, Medical and Related Science Centre, 101 College Street, Toronto, Ontario M5G 1L7, Canada. fax: (416) 581-7487.
| | | | - Gary F. Lewis
- Correspondence Address correspondence to: Gary F. Lewis, MD, FRCPC, Toronto General Hospital, 200 Elizabeth Street, EN12-218, Toronto, Ontario M5G 2C4, Canada. fax: (416) 340-3314.
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Xiao C, Stahel P, Carreiro AL, Hung YH, Dash S, Bookman I, Buhman KK, Lewis GF. Oral Glucose Mobilizes Triglyceride Stores From the Human Intestine. Cell Mol Gastroenterol Hepatol 2018; 7:313-337. [PMID: 30704982 PMCID: PMC6357697 DOI: 10.1016/j.jcmgh.2018.10.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 10/05/2018] [Accepted: 10/05/2018] [Indexed: 12/22/2022]
Abstract
BACKGROUND & AIMS The small intestine regulates plasma triglyceride (TG) concentration. Within enterocytes, dietary TGs are packaged into chylomicrons (CMs) for secretion or stored temporarily in cytoplasmic lipid droplets (CLDs) until further mobilization. We and others have shown that oral and intravenous glucose enhances CM particle secretion in human beings, however, the mechanisms through which this occurs are incompletely understood. METHODS Two separate cohorts of participants ingested a high-fat liquid meal and, 5 hours later, were assigned randomly to ingest either a glucose solution or an equivalent volume of water. In 1 group (N = 6), plasma and lipoprotein TG responses were assessed in a randomized cross-over study. In a separate group (N = 24), duodenal biopsy specimens were obtained 1 hour after ingestion of glucose or water. Ultrastructural and proteomic analyses were performed on duodenal biopsy specimens. RESULTS Compared with water, glucose ingestion increased circulating TGs within 30 minutes, mainly in the CM fraction. It decreased the total number of CLDs and the proportion of large-sized CLDs within enterocytes. We identified 2919 proteins in human duodenal tissue, 270 of which are related to lipid metabolism and 134 of which were differentially present in response to glucose compared with water ingestion. CONCLUSIONS Oral glucose mobilizes TGs stored within enterocyte CLDs to provide substrate for CM synthesis and secretion. Future studies elucidating the underlying signaling pathways may provide mechanistic insights that lead to the development of novel therapeutics for the treatment of hypertriglyceridemia.
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Affiliation(s)
- Changting Xiao
- Division of Endocrinology and Metabolism, Departments of Medicine and Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Priska Stahel
- Division of Endocrinology and Metabolism, Departments of Medicine and Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Alicia L. Carreiro
- Department of Nutrition Science, Purdue University, West Lafayette, Indiana
| | - Yu-Han Hung
- Department of Nutrition Science, Purdue University, West Lafayette, Indiana
| | - Satya Dash
- Division of Endocrinology and Metabolism, Departments of Medicine and Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Ian Bookman
- Kensington Screening Clinic, Toronto, Ontario, Canada
| | - Kimberly K. Buhman
- Department of Nutrition Science, Purdue University, West Lafayette, Indiana
| | - Gary F. Lewis
- Division of Endocrinology and Metabolism, Departments of Medicine and Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada,Correspondence Address correspondence to: Gary F. Lewis, MD, FRCPC, Toronto General Hospital, 200 Elizabeth Street, EN12-218, Toronto, Ontario, M5G 2C4 Canada. fax: (416) 340-3314.
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Abstract
The effects of intranasal insulin on the regulation of endogenous glucose production (EGP) in individuals with insulin resistance were assessed in a single-blind, crossover study. Overweight or obese insulin-resistant men (n = 7; body mass index 35.4 ± 4.4 kg/m2 , homeostatic model assessment of insulin resistance 5.6 ± 1.6) received intranasal spray of either 40 IU insulin lispro or placebo in 2 randomized visits. Acute systemic spillover of intranasal insulin into the circulation was matched with a 30-minute intravenous infusion of insulin lispro in the nasal placebo arm. EGP was assessed under conditions of a pancreatic clamp with a primed, constant infusion of glucose tracer. Under these experimental conditions, compared with placebo, intranasal administration of insulin did not significantly affect plasma glucose concentrations, EGP or glucose disposal in overweight/obese, insulin-resistant men, in contrast to our previous study, in which an equivalent dose of intranasal insulin significantly suppressed EGP in lean, insulin-sensitive men. Insulin resistance is probably associated with impairment in centrally mediated insulin suppression of EGP.
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Affiliation(s)
- Changting Xiao
- Division of Endocrinology and Metabolism, Departments of Medicine and Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Satya Dash
- Division of Endocrinology and Metabolism, Departments of Medicine and Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Priska Stahel
- Division of Endocrinology and Metabolism, Departments of Medicine and Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Gary F Lewis
- Division of Endocrinology and Metabolism, Departments of Medicine and Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
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Xiao C, Stahel P, Dash S, Morgantini C, Lewis GF. Investigation of the Role of Enteric Blood Flow in Mediating GLP-2 Stimulation of Triglyceride Mobilization and Chylomicron Secretion in the Human Intestine. ATHEROSCLEROSIS SUPP 2018. [DOI: 10.1016/j.atherosclerosissup.2018.04.082] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Stahel P, Xiao C, Carreiro AL, Hung YH, Zembroski A, Dash S, Buhman KK, Lewis GF. Oral Glucose Mobilizes Triglyceride Stores from the Human Intestine. ATHEROSCLEROSIS SUPP 2018. [DOI: 10.1016/j.atherosclerosissup.2018.04.063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Stahel P, Xiao C, Hegele RA, Lewis GF. The Atherogenic Dyslipidemia Complex and Novel Approaches to Cardiovascular Disease Prevention in Diabetes. Can J Cardiol 2018; 34:595-604. [DOI: 10.1016/j.cjca.2017.12.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 12/04/2017] [Accepted: 12/07/2017] [Indexed: 10/18/2022] Open
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Xiao C, Stahel P, Carreiro AL, Buhman KK, Lewis GF. Recent Advances in Triacylglycerol Mobilization by the Gut. Trends Endocrinol Metab 2018; 29:151-163. [PMID: 29306629 DOI: 10.1016/j.tem.2017.12.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 11/30/2017] [Accepted: 12/04/2017] [Indexed: 11/26/2022]
Abstract
Dietary lipid absorption and lipoprotein secretion by the gut are important in maintaining whole-body energy homeostasis and have significant implications for health and disease. The processing of dietary lipids, including storage within and subsequent mobilization and transport from enterocyte cytoplasmic lipid droplets or other intestinal lipid storage pools (including the secretary pathway, lamina propria and lymphatics) and secretion of chylomicrons, involves coordinated steps that are subject to various controls. This review summarizes recent advances in our understanding of the mechanisms that underlie lipid storage and mobilization by small intestinal enterocytes and the intestinal lymphatic vasculature. Therapeutic targeting of lipid processing by the gut may provide opportunities for the treatment and prevention of dyslipidemia, and for improving health status.
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Affiliation(s)
- Changting Xiao
- Departments of Medicine and Physiology, Division of Endocrinology and Metabolism, Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, Canada
| | - Priska Stahel
- Departments of Medicine and Physiology, Division of Endocrinology and Metabolism, Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, Canada
| | - Alicia L Carreiro
- Department of Nutrition Science, Purdue University, West Lafayette, IN 47907, USA
| | - Kimberly K Buhman
- Department of Nutrition Science, Purdue University, West Lafayette, IN 47907, USA
| | - Gary F Lewis
- Departments of Medicine and Physiology, Division of Endocrinology and Metabolism, Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, Canada.
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Abstract
PURPOSE OF REVIEW Dyslipidemia is a major risk factor for atherosclerotic cardiovascular disease (CVD). Lipoproteins secreted by the intestine can contribute to dyslipidemia and may increase risk for CVD. This review focuses on how dietary carbohydrates can impact the production of chylomicrons, thereby influencing plasma concentrations of triglycerides and lipoproteins. RECENT FINDINGS Hypercaloric diets high in monosaccharides can exacerbate postprandial triglyceride concentration. In contrast, isocaloric substitution of monosaccharides into mixed meals has no clear stimulatory or inhibitory effect on postprandial triglycerides. Mechanistic studies with oral ingestion of carbohydrates or elevation of plasma glucose have demonstrated enhanced secretion of chylomicrons. The mechanisms underlying this modulation remain largely unknown but may include enhanced intestinal de novo lipogenesis and mobilization of intestinally stored lipids. SUMMARY The studies reviewed here have implications for dietary recommendations regarding refined carbohydrate intake and prevention of CVD.
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Affiliation(s)
- Priska Stahel
- Departments of Medicine and Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
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Dash S, Xiao C, Stahel P, Koulajian K, Giacca A, Lewis GF. Evaluation of the specific effects of intranasal glucagon on glucose production and lipid concentration in healthy men during a pancreatic clamp. Diabetes Obes Metab 2018; 20:328-334. [PMID: 28730676 DOI: 10.1111/dom.13069] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2017] [Revised: 07/01/2017] [Accepted: 07/13/2017] [Indexed: 01/19/2023]
Abstract
AIM To investigate the specific effects of intranasal glucagon (ING) on plasma glucose, endogenous glucose production (EGP) and lipid concentration. METHODS We conducted a single-blind, randomized, crossover study at our academic investigation unit. Under pancreatic clamp conditions with tracer infusion, 1 mg ING or intranasal placebo (INP) was administered to 10 healthy men. As pilot studies showed that ING transiently increased plasma glucagon, we infused intravenous glucagon for 30 minutes along with INP to ensure similar plasma glucagon concentrations between interventions. The main outcome measures were plasma glucose, EGP, free fatty acid (FFA) and triglyceride (TG) concentrations. RESULTS In the presence of similar plasma glucagon concentrations, the increase in plasma glucose under these experimental conditions was attenuated with ING (mean plasma glucose analysis of variance P < .001) with reduction in EGP (P = .027). No significant differences were seen in plasma FFA and TG concentrations. CONCLUSION ING raises plasma glucose but this route of administration attenuates the gluco-stimulatory effect of glucagon by reducing EGP. This observation invites speculation about a potential central nervous system effect of glucagon, which requires further investigation. If ING is developed as a treatment for hypoglycaemia, this attenuated effect on plasma glucose should be taken into account.
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Affiliation(s)
- Satya Dash
- Departments of Medicine and Physiology and the Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
- Division of Endocrinology, Department of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Changting Xiao
- Departments of Medicine and Physiology and the Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
- Division of Endocrinology, Department of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Priska Stahel
- Departments of Medicine and Physiology and the Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
- Division of Endocrinology, Department of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Khajag Koulajian
- Departments of Medicine and Physiology and the Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
- Division of Endocrinology, Department of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Adria Giacca
- Departments of Medicine and Physiology and the Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Gary F Lewis
- Departments of Medicine and Physiology and the Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
- Division of Endocrinology, Department of Medicine, University of Toronto, Toronto, Ontario, Canada
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Ivovic A, Oprescu AI, Koulajian K, Mori Y, Eversley JA, Zhang L, Nino-Fong R, Lewis GF, Donath MY, Karin M, Wheeler MB, Ehses J, Volchuk A, Chan CB, Giacca A. IKKβ inhibition prevents fat-induced beta cell dysfunction in vitro and in vivo in rodents. Diabetologia 2017; 60:2021-2032. [PMID: 28725915 DOI: 10.1007/s00125-017-4345-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 05/16/2017] [Indexed: 02/07/2023]
Abstract
AIMS/HYPOTHESIS We have previously shown that oxidative stress plays a causal role in beta cell dysfunction induced by fat. Here, we address whether the proinflammatory kinase inhibitor of (nuclear factor) κB kinase β (IKKβ), which is activated by oxidative stress, is also implicated. METHODS Fat (oleate or olive oil) was infused intravenously in Wistar rats for 48 h with or without the IKKβ inhibitor salicylate. Thereafter, beta cell function was evaluated in vivo using hyperglycaemic clamps or ex vivo in islets isolated from fat-treated rats. We also exposed rat islets to oleate in culture, with or without salicylate and 4(2'-aminoethyl)amino-1,8-dimethylimidazo(1,2-a)quinoxaline; BMS-345541 (BMS, another inhibitor of IKKβ) and evaluated beta cell function in vitro. Furthermore, oleate was infused in mice treated with BMS and in beta cell-specific Ikkb-null mice. RESULTS 48 h infusion of fat impaired beta-cell function in vivo, assessed using the disposition index (DI), in rats (saline: 1.41 ± 0.13; oleate: 0.95 ± 0.11; olive oil [OLO]: 0.87 ± 0.15; p < 0.01 for both fats vs saline) and in mice (saline: 2.51 ± 0.39; oleate: 1.20 ± 0.19; p < 0.01 vs saline) and ex vivo (i.e., insulin secretion, units are pmol insulin islet-1 h-1) in rat islets (saline: 1.51 ± 0.13; oleate: 1.03 ± 0.10; OLO: 0.91 ± 0.13; p < 0.001 for both fats vs saline) and the dysfunction was prevented by co-infusion of salicylate in rats (oleate + salicylate: 1.30 ± 0.09; OLO + salicylate: 1.33 ± 0.23) or BMS in mice (oleate + BMS: 2.25 ± 0.42) in vivo and by salicylate in rat islets ex vivo (oleate + salicylate: 1.74 ± 0.31; OLO + salicylate: 1.54 ± 0.29). In cultured islets, 48 h exposure to oleate impaired beta-cell function ([in pmol insulin islet-1 h-1] control: 0.66 ± 0.12; oleate: 0.23 ± 0.03; p < 0.01 vs saline), an effect prevented by both inhibitors (oleate + salicylate: 0.98 ± 0.08; oleate + BMS: 0.50 ± 0.02). Genetic inhibition of IKKβ also prevented fat-induced beta-cell dysfunction ex vivo ([in pmol insulin islet-1 h-1] control saline: 0.16 ± 0.02; control oleate: 0.10 ± 0.02; knockout oleate: 0.17 ± 0.04; p < 0.05 control saline vs. control oleate) and in vivo (DI: control saline: 3.86 ± 0.40; control oleate: 1.95 ± 0.29; knockout oleate: 2.96 ± 0.24; p < 0.01 control saline vs control oleate). CONCLUSIONS/INTERPRETATION Our results demonstrate a causal role for IKKβ in fat-induced beta cell dysfunction in vitro, ex vivo and in vivo.
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Affiliation(s)
- Aleksandar Ivovic
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada, M5S 1A8
| | - Andrei I Oprescu
- Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Khajag Koulajian
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada, M5S 1A8
| | - Yusaku Mori
- Division of Diabetes, Metabolism, and Endocrinology, Showa University School of Medicine, Shinagawa, Tokyo, Japan
| | - Judith A Eversley
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada, M5S 1A8
| | - Liling Zhang
- Division of Cellular and Molecular Biology, Toronto General Research Institute, University Health Network, Toronto, ON, Canada
| | - Rodolfo Nino-Fong
- Department of Biomedical Sciences, Ross University School of Veterinary Medicine, Basseterre, St Kitts and Nevis
| | - Gary F Lewis
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada, M5S 1A8
- Department of Medicine, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
- Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, Canada
| | - Marc Y Donath
- Department of Endocrinology, Diabetes, and Metabolism, University Hospital Basel, Basel, Switzerland
| | - Michael Karin
- Department of Pharmacology, University of California, San Diego, School of Medicine, La Jolla, CA, USA
| | - Michael B Wheeler
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada, M5S 1A8
| | - Jan Ehses
- Department of Surgery, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
- Child and Family Research Institute, Vancouver, BC, Canada
| | - Allen Volchuk
- Keenan Research Centre for Biomedical Science, St Michael's Hospital, Toronto, ON, Canada
| | - Catherine B Chan
- Department of Agriculture, Food and Nutritional Sciences, Faculty of Agricultural, Life and Environmental Sciences, University of Alberta, Edmonton, AB, Canada
- Department of Physiology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Adria Giacca
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada, M5S 1A8.
- Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.
- Department of Medicine, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.
- Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, Canada.
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Affiliation(s)
- Priska Stahel
- From Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada; Robarts Research Institute, London, Ontario, Canada; Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Changting Xiao
- From Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada; Robarts Research Institute, London, Ontario, Canada; Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Robert A Hegele
- From Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada; Robarts Research Institute, London, Ontario, Canada; Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Gary F Lewis
- From Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada; Robarts Research Institute, London, Ontario, Canada; Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
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Xiao C, Dash S, Stahel P, Lewis GF. Effects of Intranasal Insulin on Triglyceride-Rich Lipoprotein Particle Production in Healthy Men. Arterioscler Thromb Vasc Biol 2017; 37:1776-1781. [DOI: 10.1161/atvbaha.117.309705] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 07/17/2017] [Indexed: 02/07/2023]
Affiliation(s)
- Changting Xiao
- From the Division of Endocrinology and Metabolism, Department of Medicine and Department of Physiology, Banting and Best Diabetes Centre, University of Toronto, Ontario, Canada
| | - Satya Dash
- From the Division of Endocrinology and Metabolism, Department of Medicine and Department of Physiology, Banting and Best Diabetes Centre, University of Toronto, Ontario, Canada
| | - Priska Stahel
- From the Division of Endocrinology and Metabolism, Department of Medicine and Department of Physiology, Banting and Best Diabetes Centre, University of Toronto, Ontario, Canada
| | - Gary F. Lewis
- From the Division of Endocrinology and Metabolism, Department of Medicine and Department of Physiology, Banting and Best Diabetes Centre, University of Toronto, Ontario, Canada
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van Zutphen T, Ciapaite J, Bloks VW, Ackereley C, Gerding A, Jurdzinski A, de Moraes RA, Zhang L, Wolters JC, Bischoff R, Wanders RJ, Houten SM, Bronte-Tinkew D, Shatseva T, Lewis GF, Groen AK, Reijngoud DJ, Bakker BM, Jonker JW, Kim PK, Bandsma RHJ. Malnutrition-associated liver steatosis and ATP depletion is caused by peroxisomal and mitochondrial dysfunction. J Hepatol 2016; 65:1198-1208. [PMID: 27312946 DOI: 10.1016/j.jhep.2016.05.046] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 04/15/2016] [Accepted: 05/30/2016] [Indexed: 12/04/2022]
Abstract
BACKGROUND & AIMS Severe malnutrition in young children is associated with signs of hepatic dysfunction such as steatosis and hypoalbuminemia, but its etiology is unknown. Peroxisomes and mitochondria play key roles in various hepatic metabolic functions including lipid metabolism and energy production. To investigate the involvement of these organelles in the mechanisms underlying malnutrition-induced hepatic dysfunction we developed a rat model of malnutrition. METHODS Weanling rats were placed on a low protein or control diet (5% or 20% of calories from protein, respectively) for four weeks. Peroxisomal and mitochondrial structural features were characterized using immunofluorescence and electron microscopy. Mitochondrial function was assessed using high-resolution respirometry. A novel targeted quantitative proteomics method was applied to analyze 47 mitochondrial proteins involved in oxidative phosphorylation, tricarboxylic acid cycle and fatty acid β-oxidation pathways. RESULTS Low protein diet-fed rats developed hypoalbuminemia and hepatic steatosis, consistent with the human phenotype. Hepatic peroxisome content was decreased and metabolomic analysis indicated peroxisomal dysfunction. This was followed by changes in mitochondrial ultrastructure and increased mitochondrial content. Mitochondrial function was impaired due to multiple defects affecting respiratory chain complex I and IV, pyruvate uptake and several β-oxidation enzymes, leading to strongly reduced hepatic ATP levels. Fenofibrate supplementation restored hepatic peroxisome abundance and increased mitochondrial β-oxidation capacity, resulting in reduced steatosis and normalization of ATP and plasma albumin levels. CONCLUSIONS Malnutrition leads to severe impairments in hepatic peroxisomal and mitochondrial function, and hepatic metabolic dysfunction. We discuss the potential future implications of our findings for the clinical management of malnourished children. LAY SUMMARY Severe malnutrition in children is associated with metabolic disturbances that are poorly understood. In order to study this further, we developed a malnutrition animal model and found that severe malnutrition leads to an impaired function of liver mitochondria which are essential for energy production and a loss of peroxisomes, which are important for normal liver metabolic function.
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Affiliation(s)
- Tim van Zutphen
- Department of Pediatrics, Center for Liver, Digestive and Metabolic Diseases, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Jolita Ciapaite
- Department of Pediatrics, Center for Liver, Digestive and Metabolic Diseases, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands; Systems Biology Centre for Energy Metabolism and Ageing, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
| | - Vincent W Bloks
- Department of Pediatrics, Center for Liver, Digestive and Metabolic Diseases, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Cameron Ackereley
- Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Canada
| | - Albert Gerding
- Department of Pediatrics, Center for Liver, Digestive and Metabolic Diseases, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Angelika Jurdzinski
- Department of Pediatrics, Center for Liver, Digestive and Metabolic Diseases, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Roberta Allgayer de Moraes
- Department of Pediatrics, Center for Liver, Digestive and Metabolic Diseases, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Ling Zhang
- Physiology and Experimental Medicine Program, Research Institute, The Hospital for Sick Children, Toronto, Canada
| | - Justina C Wolters
- Systems Biology Centre for Energy Metabolism and Ageing, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands; Department of Pharmacy, Analytical Biochemistry, University of Groningen, Groningen, The Netherlands
| | - Rainer Bischoff
- Systems Biology Centre for Energy Metabolism and Ageing, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands; Department of Pharmacy, Analytical Biochemistry, University of Groningen, Groningen, The Netherlands
| | - Ronald J Wanders
- Laboratory Genetic Metabolic Diseases, Departments of Pediatrics and Clinical Chemistry, Academic Medical Center, Amsterdam, The Netherlands (current address: Icahn Institute for Genomics and Multiscale Biology, New York, USA)
| | - Sander M Houten
- Laboratory Genetic Metabolic Diseases, Departments of Pediatrics and Clinical Chemistry, Academic Medical Center, Amsterdam, The Netherlands (current address: Icahn Institute for Genomics and Multiscale Biology, New York, USA)
| | | | - Tatiana Shatseva
- Program in Cell Biology, Hospital for Sick Children, Toronto, Canada
| | - Gary F Lewis
- The Division of Endocrinology and Metabolism, Department of Medicine and the Banting and Best Diabetes Centre, University of Toronto, Toronto, Canada
| | - Albert K Groen
- Department of Pediatrics, Center for Liver, Digestive and Metabolic Diseases, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Dirk-Jan Reijngoud
- Department of Pediatrics, Center for Liver, Digestive and Metabolic Diseases, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Barbara M Bakker
- Department of Pediatrics, Center for Liver, Digestive and Metabolic Diseases, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands; Systems Biology Centre for Energy Metabolism and Ageing, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
| | - Johan W Jonker
- Department of Pediatrics, Center for Liver, Digestive and Metabolic Diseases, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Peter K Kim
- Program in Cell Biology, Hospital for Sick Children, Toronto, Canada; Department of Biochemistry, University of Toronto, Toronto, Canada.
| | - Robert H J Bandsma
- Department of Pediatrics, Center for Liver, Digestive and Metabolic Diseases, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands; Physiology and Experimental Medicine Program, Research Institute, The Hospital for Sick Children, Toronto, Canada; Division of Gastroenterology, Hepatology and Nutrition, The Hospital for Sick Children, Toronto, Canada; Centre for Global Child Health, The Hospital for Sick Children, Toronto, Canada.
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Xiao C, Dash S, Morgantini C, Hegele RA, Lewis GF. Pharmacological Targeting of the Atherogenic Dyslipidemia Complex: The Next Frontier in CVD Prevention Beyond Lowering LDL Cholesterol. Diabetes 2016; 65:1767-78. [PMID: 27329952 DOI: 10.2337/db16-0046] [Citation(s) in RCA: 124] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2016] [Accepted: 03/23/2016] [Indexed: 11/13/2022]
Abstract
Notwithstanding the effectiveness of lowering LDL cholesterol, residual CVD risk remains in high-risk populations, including patients with diabetes, likely contributed to by non-LDL lipid abnormalities. In this Perspectives in Diabetes article, we emphasize that changing demographics and lifestyles over the past few decades have resulted in an epidemic of the "atherogenic dyslipidemia complex," the main features of which include hypertriglyceridemia, low HDL cholesterol levels, qualitative changes in LDL particles, accumulation of remnant lipoproteins, and postprandial hyperlipidemia. We briefly review the underlying pathophysiology of this form of dyslipidemia, in particular its association with insulin resistance, obesity, and type 2 diabetes, and the marked atherogenicity of this condition. We explain the failure of existing classes of therapeutic agents such as fibrates, niacin, and cholesteryl ester transfer protein inhibitors that are known to modify components of the atherogenic dyslipidemia complex. Finally, we discuss targeted repurposing of existing therapies and review promising new therapeutic strategies to modify the atherogenic dyslipidemia complex. We postulate that targeting the central abnormality of the atherogenic dyslipidemia complex, the elevation of triglyceride-rich lipoprotein particles, represents a new frontier in CVD prevention and is likely to prove the most effective strategy in correcting most aspects of the atherogenic dyslipidemia complex, thereby preventing CVD events.
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Affiliation(s)
- Changting Xiao
- Departments of Medicine and Physiology and the Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Satya Dash
- Departments of Medicine and Physiology and the Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Cecilia Morgantini
- Departments of Medicine and Physiology and the Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Robert A Hegele
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Gary F Lewis
- Departments of Medicine and Physiology and the Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
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Revelo XS, Ghazarian M, Chng MHY, Luck H, Kim JH, Zeng K, Shi SY, Tsai S, Lei H, Kenkel J, Liu CL, Tangsombatvisit S, Tsui H, Sima C, Xiao C, Shen L, Li X, Jin T, Lewis GF, Woo M, Utz PJ, Glogauer M, Engleman E, Winer S, Winer DA. Nucleic Acid-Targeting Pathways Promote Inflammation in Obesity-Related Insulin Resistance. Cell Rep 2016; 16:717-30. [PMID: 27373163 DOI: 10.1016/j.celrep.2016.06.024] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 04/27/2016] [Accepted: 06/03/2016] [Indexed: 12/22/2022] Open
Abstract
Obesity-related inflammation of metabolic tissues, including visceral adipose tissue (VAT) and liver, are key factors in the development of insulin resistance (IR), though many of the contributing mechanisms remain unclear. We show that nucleic-acid-targeting pathways downstream of extracellular trap (ET) formation, unmethylated CpG DNA, or ribonucleic acids drive inflammation in IR. High-fat diet (HFD)-fed mice show increased release of ETs in VAT, decreased systemic clearance of ETs, and increased autoantibodies against conserved nuclear antigens. In HFD-fed mice, this excess of nucleic acids and related protein antigens worsens metabolic parameters through a number of mechanisms, including activation of VAT macrophages and expansion of plasmacytoid dendritic cells (pDCs) in the liver. Consistently, HFD-fed mice lacking critical responders of nucleic acid pathways, Toll-like receptors (TLR)7 and TLR9, show reduced metabolic inflammation and improved glucose homeostasis. Treatment of HFD-fed mice with inhibitors of ET formation or a TLR7/9 antagonist improves metabolic disease. These findings reveal a pathogenic role for nucleic acid targeting as a driver of metabolic inflammation in IR.
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Affiliation(s)
- Xavier S Revelo
- Division of Cellular and Molecular Biology, Diabetes Research Group, Toronto General Research Institute (TGRI), University Health Network, Toronto, ON M5G 1L7, Canada.
| | - Magar Ghazarian
- Division of Cellular and Molecular Biology, Diabetes Research Group, Toronto General Research Institute (TGRI), University Health Network, Toronto, ON M5G 1L7, Canada
| | - Melissa Hui Yen Chng
- Department of Pathology, Stanford University School of Medicine, Palo Alto, CA 94305, USA
| | - Helen Luck
- Division of Cellular and Molecular Biology, Diabetes Research Group, Toronto General Research Institute (TGRI), University Health Network, Toronto, ON M5G 1L7, Canada
| | - Justin H Kim
- Division of Cellular and Molecular Biology, Diabetes Research Group, Toronto General Research Institute (TGRI), University Health Network, Toronto, ON M5G 1L7, Canada
| | - Kejing Zeng
- Division of Cellular and Molecular Biology, Diabetes Research Group, Toronto General Research Institute (TGRI), University Health Network, Toronto, ON M5G 1L7, Canada; Department of Endocrinology and Metabolism, Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou 510630, China
| | - Sally Y Shi
- Division of Cellular and Molecular Biology, Diabetes Research Group, Toronto General Research Institute (TGRI), University Health Network, Toronto, ON M5G 1L7, Canada
| | - Sue Tsai
- Division of Cellular and Molecular Biology, Diabetes Research Group, Toronto General Research Institute (TGRI), University Health Network, Toronto, ON M5G 1L7, Canada
| | - Helena Lei
- Division of Cellular and Molecular Biology, Diabetes Research Group, Toronto General Research Institute (TGRI), University Health Network, Toronto, ON M5G 1L7, Canada
| | - Justin Kenkel
- Department of Pathology, Stanford University School of Medicine, Palo Alto, CA 94305, USA
| | - Chih Long Liu
- Department of Medicine, Division of Immunology and Rheumatology, Stanford University School of Medicine, Palo Alto, CA 94305, USA
| | - Stephanie Tangsombatvisit
- Department of Medicine, Division of Immunology and Rheumatology, Stanford University School of Medicine, Palo Alto, CA 94305, USA
| | - Hubert Tsui
- Department of Pathology, University Health Network, Toronto, ON M5G 2C4, Canada
| | - Corneliu Sima
- Department of Applied Oral Sciences, The Forsyth Institute, Cambridge, MA 02142, USA
| | - Changting Xiao
- Division of Endocrinology and Metabolism, Department of Medicine, University Health Network, Toronto, ON M5G 2C4, Canada
| | - Lei Shen
- Shanghai Institute of Immunology, Shanghai Jiao Tong University School of Medicine, Shanghai 200240, China
| | - Xiaoying Li
- Department of Endocrinology, Zhongshan Hospital, Fudan University, Shanghai 200011, China
| | - Tianru Jin
- Division of Cellular and Molecular Biology, Diabetes Research Group, Toronto General Research Institute (TGRI), University Health Network, Toronto, ON M5G 1L7, Canada
| | - Gary F Lewis
- Division of Endocrinology and Metabolism, Department of Medicine, University Health Network, Toronto, ON M5G 2C4, Canada
| | - Minna Woo
- Division of Cellular and Molecular Biology, Diabetes Research Group, Toronto General Research Institute (TGRI), University Health Network, Toronto, ON M5G 1L7, Canada; Division of Endocrinology and Metabolism, Department of Medicine, University Health Network, Toronto, ON M5G 2C4, Canada
| | - Paul J Utz
- Department of Medicine, Division of Immunology and Rheumatology, Stanford University School of Medicine, Palo Alto, CA 94305, USA
| | - Michael Glogauer
- Faculty of Dentistry, University of Toronto, Matrix Dynamics Group, Toronto, ON M5G 1G6, Canada
| | - Edgar Engleman
- Department of Pathology, Stanford University School of Medicine, Palo Alto, CA 94305, USA
| | - Shawn Winer
- Division of Cellular and Molecular Biology, Diabetes Research Group, Toronto General Research Institute (TGRI), University Health Network, Toronto, ON M5G 1L7, Canada; Department of Laboratory Medicine, St. Michael's Hospital, Toronto, ON M5B 1W8, Canada; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Daniel A Winer
- Division of Cellular and Molecular Biology, Diabetes Research Group, Toronto General Research Institute (TGRI), University Health Network, Toronto, ON M5G 1L7, Canada; Department of Pathology, University Health Network, Toronto, ON M5G 2C4, Canada; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON M5S 1A8, Canada; Department of Immunology, University of Toronto, Toronto, ON M5S 1A8, Canada.
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Xiao C, Dash S, Morgantini C, Lewis GF. Intravenous Glucose Acutely Stimulates Intestinal Lipoprotein Secretion in Healthy Humans. Arterioscler Thromb Vasc Biol 2016; 36:1457-63. [PMID: 27150393 DOI: 10.1161/atvbaha.115.307044] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 04/20/2016] [Indexed: 12/28/2022]
Abstract
OBJECTIVE Increased production of intestinal triglyceride-rich lipoproteins (TRLs) contributes to dyslipidemia and increased risk of atherosclerotic cardiovascular disease in insulin resistance and type 2 diabetes. We have previously demonstrated that enteral glucose enhances lipid-stimulated intestinal lipoprotein particle secretion. Here, we assessed whether glucose delivered systemically by intravenous infusion also enhances intestinal lipoprotein particle secretion in humans. APPROACH AND RESULTS On 2 occasions, 4 to 6 weeks apart and in random order, 10 healthy men received a constant 15-hour intravenous infusion of either 20% glucose to induce hyperglycemia or normal saline as control. Production of TRL-apolipoprotein B48 (apoB48, primary outcomes) and apoB100 (secondary outcomes) was assessed during hourly liquid-mixed macronutrient formula ingestion with stable isotope enrichment and multicompartmental modeling, under pancreatic clamp conditions to limit perturbations in pancreatic hormones (insulin and glucagon) and growth hormone. Compared with saline infusion, glucose infusion induced both hyperglycemia and hyperinsulinemia, increased plasma triglyceride levels, and increased TRL-apoB48 concentration and production rate (P<0.05), without affecting TRL-apoB48 fractional catabolic rate. No significant effect of hyperglycemia on TRL-apoB100 concentration and kinetic parameters was observed. CONCLUSIONS Short-term intravenous infusion of glucose stimulates intestinal lipoprotein production. Hyperglycemia may contribute to intestinal lipoprotein overproduction in type 2 diabetes. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifier: NCT02607839.
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Affiliation(s)
- Changting Xiao
- From the Division of Endocrinology and Metabolism, Department of Medicine and Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, Canada
| | - Satya Dash
- From the Division of Endocrinology and Metabolism, Department of Medicine and Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, Canada
| | - Cecilia Morgantini
- From the Division of Endocrinology and Metabolism, Department of Medicine and Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, Canada
| | - Gary F Lewis
- From the Division of Endocrinology and Metabolism, Department of Medicine and Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, Canada.
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Jacome-Sosa M, Parks EJ, Bruno RS, Tasali E, Lewis GF, Schneeman BO, Rains TM. Postprandial Metabolism of Macronutrients and Cardiometabolic Risk: Recent Developments, Emerging Concepts, and Future Directions. Adv Nutr 2016; 7:364-74. [PMID: 26980820 PMCID: PMC4785471 DOI: 10.3945/an.115.010397] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Cardiovascular disease (CVD) is the leading cause of death in the United States. Although the role of habitual lifestyle factors such as physical activity and dietary patterns in increasing CVD risk has long been appreciated, less is known about how acute daily activities may cumulatively contribute to long-term disease risk. Here, the term acute refers to metabolic responses occurring in a short period of time after eating, and the goal of this article is to review recently identified stressors that can occur after meals and during the sleep-wake cycle to affect macronutrient metabolism. It is hypothesized that these events, when repeated on a regular basis, contribute to the observed long-term behavioral risks identified in population studies. In this regard, developments in research methods have supported key advancements in 3 fields of macronutrient metabolism. The first of these research areas is the focus on the immediate postmeal metabolism, spanning from early intestinal adsorptive events to the impact of incretin hormones on these events. The second topic is a focus on the importance of meal components on postprandial vasculature function. Finally, some of the most exciting advances are being made in understanding dysregulation in metabolism early in the day, due to insufficient sleep, that may affect subsequent processing of nutrients throughout the day. Key future research questions are highlighted which will lead to a better understanding of the relations between nocturnal, basal (fasting), and early postmeal events, and aid in the development of optimal sleep and targeted dietary patterns to reduce cardiometabolic risk.
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Affiliation(s)
- Miriam Jacome-Sosa
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, MO
| | - Elizabeth J Parks
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, MO;
| | - Richard S Bruno
- Human Nutrition Program, Department of Human Sciences, The Ohio State University, Columbus, OH
| | - Esra Tasali
- Department of Medicine, The University of Chicago, Chicago, IL
| | - Gary F Lewis
- Banting and Best Diabetes Center and Departments of Medicine and Physiology, Division of Endocrinology and Metabolism, University of Toronto, Toronto, Canada
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Abstract
PURPOSE OF REVIEW Insulin resistance and type 2 diabetes, driven largely by obesity, are characterized by an increase in triglyceride-rich lipoproteins (TRLs) due to both reduced TRL clearance from the circulation and increased production by the liver (apoB-100 containing VLDLs) and intestine (apoB-48 containing chylomicrons). Bariatric surgery is the only treatment currently that leads to marked, sustained weight loss. Here, we will review the effects of bariatric surgery on circulating triglyceride/TRL and TRL production and clearance. RECENT FINDINGS Bariatric surgery leads to a marked reduction in fasting and postprandial plasma triglyceride. Only one study to date has assessed TRL kinetics after bariatric surgery and has reported a reduction in TRL apoB-100 concentration (i.e. the number of VLDL particles) due to reduced production and increased clearance and reduced TRL apoB-48 concentration (the number of chylomicron particles) due to reduced production. Some bariatric surgery studies have reported no/weak correlation between weight loss and improvements in triglyceride/TRL, suggesting that as yet unidentified factors beyond weight loss may contribute to the marked changes in TRL that occur postbariatric surgery. SUMMARY Available data suggest that bariatric surgery reduces triglyceride and intestinal and hepatic TRL production with increased clearance of hepatic TRL particles. These effects of bariatric surgery on TRL kinetics need to be confirmed with additional studies. Further studies are also needed to compare the effects of various bariatric surgery procedures on TRL kinetics and to elucidate underlying mechanisms.
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Affiliation(s)
- Satya Dash
- aDepartment of Medicine bDepartment of Physiology and Banting and Best Diabetes Centre cDivision of Endocrinology, Department of Medicine, University of Toronto, Toronto, Ontario, Canada
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Goyal S, Morita P, Lewis GF, Yu C, Seto E, Cafazzo JA. The Systematic Design of a Behavioural Mobile Health Application for the Self-Management of Type 2 Diabetes. Can J Diabetes 2015; 40:95-104. [PMID: 26455762 DOI: 10.1016/j.jcjd.2015.06.007] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 04/23/2015] [Accepted: 06/17/2015] [Indexed: 11/25/2022]
Abstract
Patients with diabetes often face serious complications due to limited self-management skills, the inability to adhere to care regimens, and psychosocial factors. Although regular self-monitoring of blood glucose is known to benefit patients receiving insulin therapy, its role in patients not treated with insulin has been unclear. However, recent studies have demonstrated that structured self-monitoring of blood glucose can significantly benefit patients who are not taking insulin, facilitating improved self-awareness and clinical decision making. We hypothesize that effective self-management by patients with type 2 diabetes who do not need insulin requires a behavioural intervention that enables the association between lifestyle behaviours, such as dietary intake and physical activity, and overall glycemic control. Mobile health applications (apps), coupled with wireless medical peripheral devices, can facilitate self-monitoring; deliver tailored, actionable knowledge; elicit positive behaviour changes and promote effective self-management of diabetes. Although existing apps incorporate tracking and feedback from healthcare providers, few attempt to elicit positive behaviour changes for the purposes of developing patients' self-care skills. The purpose of this article is to present a systematic approach to the design and development a diabetes self-management mobile app, which included 1) a scoping review of literature; 2) the development of an overarching theoretical approach and 3) validation of the app features through user-centred design methods. The resulting app, bant II, facilitates 1) self-monitoring of blood glucose, physical activity, diet and weight; 2) identification of glycemic patterns in relation to lifestyle; 3) remedial decision making and 4) positive behaviour change through incentives.
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Affiliation(s)
- Shivani Goyal
- Centre for Global eHealth Innovation, Techna Institute, University Health Network, Toronto, Ontario, Canada; Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada.
| | - Plinio Morita
- Centre for Global eHealth Innovation, Techna Institute, University Health Network, Toronto, Ontario, Canada
| | - Gary F Lewis
- Departments of Medicine and Physiology, Division of Endocrinology and the Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Catherine Yu
- Division of Endocrinology & Metabolism and Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada; Faculty of Medicine and Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada
| | - Emily Seto
- Centre for Global eHealth Innovation, Techna Institute, University Health Network, Toronto, Ontario, Canada; Institute of Health Policy, Management and Evaluation, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Joseph A Cafazzo
- Centre for Global eHealth Innovation, Techna Institute, University Health Network, Toronto, Ontario, Canada; Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada; Institute of Health Policy, Management and Evaluation, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
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Bandsma RHJ, Ackerley C, Koulajian K, Zhang L, van Zutphen T, van Dijk TH, Xiao C, Giacca A, Lewis GF. A low-protein diet combined with low-dose endotoxin leads to changes in glucose homeostasis in weanling rats. Am J Physiol Endocrinol Metab 2015; 309:E466-73. [PMID: 26152763 DOI: 10.1152/ajpendo.00090.2015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 07/01/2015] [Indexed: 12/23/2022]
Abstract
Severe malnutrition is a leading cause of global childhood mortality, and infection and hypoglycemia or hyperglycemia are commonly present. The etiology behind the changes in glucose homeostasis is poorly understood. Here, we generated an animal model of severe malnutrition with and without low-grade inflammation to investigate the effects on glucose homeostasis. Immediately after weaning, rats were fed diets containing 5 [low-protein diet (LP)] or 20% protein [control diet (CTRL)], with or without repeated low-dose intraperitoneal lipopolysaccharide (LPS; 2 mg/kg), to mimic inflammation resulting from infections. After 4 wk on the diets, hyperglycemic clamps or euglycemic hyperinsulinemic clamps were performed with infusion of [U-(13)C6]glucose and [2-(13)C]glycerol to assess insulin secretion, action, and hepatic glucose metabolism. In separate studies, pancreatic islets were isolated for further analyses of insulin secretion and islet morphometry. Glucose clearance was reduced significantly by LP feeding alone (16%) and by LP feeding with LPS administration (43.8%) compared with control during the hyperglycemic clamps. This was associated with a strongly reduced insulin secretion in LP-fed rats in vivo as well as ex vivo in islets but signficantly enhanced whole body insulin sensitivity. Gluconeogenesis rates were unaffected by LP feeding, but glycogenolysis was higher after LP feeding. A protein-deficient diet in young rats leads to a susceptibility to low-dose endotoxin-induced impairment in glucose clearance with a decrease in the islet insulin secretory pathway. A protein-deficient diet is associated with enhanced peripheral insulin sensitivity but impaired insulin-mediated suppression of hepatic glycogenolysis.
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Affiliation(s)
- Robert H J Bandsma
- Division of Gastroenterology, Hepatology, and Nutrition, The Hospital for Sick Children, Toronto, Ontario, Canada; Physiology and Experimental Medicine Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Pediatrics, Center for Liver, Digestive, and Metabolic Diseases, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands;
| | - Cameron Ackerley
- Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Khajag Koulajian
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada; Division of Endocrinology and Metabolism, Department of Medicine, University of Toronto, Toronto, Ontario, Canada; and
| | - Ling Zhang
- Physiology and Experimental Medicine Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Tim van Zutphen
- Department of Pediatrics, Center for Liver, Digestive, and Metabolic Diseases, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Theo H van Dijk
- Department of Pediatrics, Center for Liver, Digestive, and Metabolic Diseases, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Changting Xiao
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada; Division of Endocrinology and Metabolism, Department of Medicine, University of Toronto, Toronto, Ontario, Canada; and Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Adria Giacca
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada; Division of Endocrinology and Metabolism, Department of Medicine, University of Toronto, Toronto, Ontario, Canada; and Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Gary F Lewis
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada; Division of Endocrinology and Metabolism, Department of Medicine, University of Toronto, Toronto, Ontario, Canada; and Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
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Xiao C, Dash S, Morgantini C, Koulajian K, Lewis GF. Evaluation of the Effect of Enteral Lipid Sensing on Endogenous Glucose Production in Humans. Diabetes 2015; 64:2939-43. [PMID: 25754959 DOI: 10.2337/db15-0148] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 03/04/2015] [Indexed: 11/13/2022]
Abstract
Administration of lipids into the upper intestine of rats has been shown to acutely decrease endogenous glucose production (EGP) in the preabsorptive state, postulated to act through a gut-brain-liver axis involving accumulation of long-chain fatty acyl-CoA, release of cholecystokinin, and subsequent neuronal signaling. It remains unknown, however, whether a similar gut-brain-liver axis is operative in humans. Here, we infused 20% Intralipid (a synthetic lipid emulsion) or saline intraduodenally for 90 min at 30 mL/h, 4 to 6 weeks apart, in random order, in nine healthy men. EGP was assessed under pancreatic clamp conditions with stable isotope enrichment techniques. Under these experimental conditions, intraduodenal infusion of Intralipid, compared with saline, did not affect plasma glucose concentration or EGP throughout the study period. We conclude that Intralipid infusion into the duodenum at this rate does not elicit detectable effects on glucose homeostasis or EGP in healthy men, which may reflect important interspecies differences between rodents and humans with respect to the putative gut-brain-liver axis.
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Affiliation(s)
- Changting Xiao
- Division of Endocrinology & Metabolism, Departments of Medicine and Physiology, University of Toronto, Toronto, Canada, and Banting & Best Diabetes Centre, University of Toronto, Toronto, Canada
| | - Satya Dash
- Division of Endocrinology & Metabolism, Departments of Medicine and Physiology, University of Toronto, Toronto, Canada, and Banting & Best Diabetes Centre, University of Toronto, Toronto, Canada
| | - Cecilia Morgantini
- Division of Endocrinology & Metabolism, Departments of Medicine and Physiology, University of Toronto, Toronto, Canada, and Banting & Best Diabetes Centre, University of Toronto, Toronto, Canada
| | - Khajag Koulajian
- Division of Endocrinology & Metabolism, Departments of Medicine and Physiology, University of Toronto, Toronto, Canada, and Banting & Best Diabetes Centre, University of Toronto, Toronto, Canada
| | - Gary F Lewis
- Division of Endocrinology & Metabolism, Departments of Medicine and Physiology, University of Toronto, Toronto, Canada, and Banting & Best Diabetes Centre, University of Toronto, Toronto, Canada
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Abstract
PURPOSE In addition to its direct action on the liver to lower hepatic glucose production, insulin action in the central nervous system (CNS) also lowers hepatic glucose production in rodents after 4 hours. Although CNS insulin action (CNSIA) modulates hepatic glycogen synthesis in dogs, it has no net effect on hepatic glucose output over a 4-hour period. The role of CNSIA in regulating plasma glucose has recently been examined in humans and is the focus of this review. METHODS AND RESULTS Intransal insulin (INI) administration increases CNS insulin concentration. Hence, INI can address whether CNSIA regulates plasma glucose concentration in humans. We and three other groups have sought to answer this question, with differing conclusions. Here we will review the critical aspects of each study, including its design, which may explain these discordant conclusions. CONCLUSIONS The early glucose-lowering effect of INI is likely due to spillover of insulin into the systemic circulation. In the presence of simultaneous portal and CNS hyperinsulinemia, portal insulin action is dominant. INI administration does lower plasma glucose independent of peripheral insulin concentration (between ∼3 and 6 h after administration), suggesting that CNSIA may play a role in glucose homeostasis in the late postprandial period when its action is likely greatest and portal insulin concentration is at baseline. The potential physiological role and purpose of this pathway are discussed in this review. Because the effects of INI are attenuated in patients with type 2 diabetes and obesity, this is unlikely to be of therapeutic utility.
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Affiliation(s)
- Satya Dash
- Departments of Medicine and Physiology and the Banting and Best Diabetes Centre, and Division of Endocrinology, Department of Medicine, University of Toronto, Toronto, ON M5G 2C4, Canada
| | - Changting Xiao
- Departments of Medicine and Physiology and the Banting and Best Diabetes Centre, and Division of Endocrinology, Department of Medicine, University of Toronto, Toronto, ON M5G 2C4, Canada
| | - Cecilia Morgantini
- Departments of Medicine and Physiology and the Banting and Best Diabetes Centre, and Division of Endocrinology, Department of Medicine, University of Toronto, Toronto, ON M5G 2C4, Canada
| | - Khajag Koulajian
- Departments of Medicine and Physiology and the Banting and Best Diabetes Centre, and Division of Endocrinology, Department of Medicine, University of Toronto, Toronto, ON M5G 2C4, Canada
| | - Gary F Lewis
- Departments of Medicine and Physiology and the Banting and Best Diabetes Centre, and Division of Endocrinology, Department of Medicine, University of Toronto, Toronto, ON M5G 2C4, Canada
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47
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Xiao C, Dash S, Morgantini C, Adeli K, Lewis GF. Gut Peptides Are Novel Regulators of Intestinal Lipoprotein Secretion: Experimental and Pharmacological Manipulation of Lipoprotein Metabolism. Diabetes 2015; 64:2310-8. [PMID: 26106188 DOI: 10.2337/db14-1706] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Individuals with metabolic syndrome and frank type 2 diabetes are at increased risk of atherosclerotic cardiovascular disease, partially due to the presence of lipid and lipoprotein abnormalities. In these conditions, the liver and intestine overproduce lipoprotein particles, exacerbating the hyperlipidemia of fasting and postprandial states. Incretin-based, antidiabetes therapies (i.e., glucagon-like peptide [GLP]-1 receptor agonists and dipeptidyl peptidase-4 inhibitors) have proven efficacy for the treatment of hyperglycemia. Evidence is accumulating that these agents also improve fasting and postprandial lipemia, the latter more significantly than the former. In contrast, the gut-derived peptide GLP-2, cosecreted from intestinal L cells with GLP-1, has recently been demonstrated to enhance intestinal lipoprotein release. Understanding the roles of these emerging regulators of intestinal lipoprotein secretion may offer new insights into the regulation of intestinal lipoprotein assembly and secretion and provide new opportunities for devising novel strategies to attenuate hyperlipidemia, with the potential for cardiovascular disease reduction.
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Affiliation(s)
- Changting Xiao
- Departments of Medicine and Physiology and Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Satya Dash
- Departments of Medicine and Physiology and Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Cecilia Morgantini
- Departments of Medicine and Physiology and Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Khosrow Adeli
- Program in Molecular Structure & Function, Research Institute, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Gary F Lewis
- Departments of Medicine and Physiology and Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
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48
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Abstract
Dietary lipids are efficiently absorbed by the small intestine, incorporated into triglyceride-rich lipoproteins (chylomicrons), and transported in the circulation to various tissues. Intestinal lipid absorption and mobilization and chylomicron synthesis and secretion are highly regulated processes. Elevated chylomicron production rate contributes to the dyslipidemia seen in common metabolic disorders such as insulin-resistant states and type 2 diabetes and likely increases the risk for atherosclerosis seen in these conditions. An in-depth understanding of the regulation of chylomicron production may provide leads for the development of drugs that could be of therapeutic utility in the prevention of dyslipidemia and atherosclerosis. Chylomicron secretion is subject to regulation by various factors, including diet, body weight, genetic variants, hormones, nutraceuticals, medications, and emerging interventions such as bariatric surgical procedures. In this review we discuss the regulation of chylomicron production, mechanisms that underlie chylomicron dysregulation, and potential avenues for future research.
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Affiliation(s)
- Satya Dash
- Departments of Medicine and Physiology and the Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, M5G 2C4 Canada;
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49
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Dash S, Xiao C, Morgantini C, Koulajian K, Lewis GF. Intranasal insulin suppresses endogenous glucose production in humans compared with placebo in the presence of similar venous insulin concentrations. Diabetes 2015; 64:766-74. [PMID: 25288674 DOI: 10.2337/db14-0685] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Intranasal insulin (INI) has been shown to modulate food intake and food-related activity in the central nervous system in humans. Because INI increases insulin concentration in the cerebrospinal fluid, these effects have been postulated to be mediated via insulin action in the brain, although peripheral effects of insulin cannot be excluded. INI has been shown to lower plasma glucose in some studies, but whether it regulates endogenous glucose production (EGP) is not known. To assess the role of INI in the regulation of EGP, eight healthy men were studied in a single-blind, crossover study with two randomized visits (one with 40 IU INI and the other with intranasal placebo [INP] administration) 4 weeks apart. EGP was assessed under conditions of an arterial pancreatic clamp, with a primed, constant infusion of deuterated glucose and infusion of 20% dextrose as required to maintain euglycemia. Between 180 and 360 min after administration, INI significantly suppressed EGP by 35.6% compared with INP, despite similar venous insulin concentrations. In conclusion, INI lowers EGP in humans compared with INP, despite similar venous insulin concentrations. INI may therefore be of value in treating excess liver glucose production in diabetes.
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Affiliation(s)
- Satya Dash
- Departments of Medicine and Physiology and the Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada, and Division of Endocrinology, Department of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Changting Xiao
- Departments of Medicine and Physiology and the Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada, and Division of Endocrinology, Department of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Cecilia Morgantini
- Departments of Medicine and Physiology and the Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada, and Division of Endocrinology, Department of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Khajag Koulajian
- Departments of Medicine and Physiology and the Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada, and Division of Endocrinology, Department of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Gary F Lewis
- Departments of Medicine and Physiology and the Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada, and Division of Endocrinology, Department of Medicine, University of Toronto, Toronto, Ontario, Canada
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50
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Abstract
Hypertriglyceridemia (HTG) is a highly prevalent condition that is associated with increased cardiovascular disease risk. HTG may arise as a result of defective metabolism of triglyceride-rich lipoproteins and their remnants, ie, impaired clearance, or increased production, or both. Current categorization of HTG segregates primary and secondary cases, implying genetic and nongenetic causes for each category. Many common and rare variants of the genes encoding factors involved in these pathways have been identified. Although monogenic forms of HTG do occur, most cases are polygenic and often coexist with nongenetic conditions. Cumulative, multiple genetic variants can increase the risks for HTG, whereas environmental and lifestyle factors can force expression of a dyslipidemic phenotype in a genetically susceptible person. HTG states are therefore best viewed as a complex phenotype resulting from the interaction of cumulated multiple susceptibility genes and environmental stressors. In view of the heterogeneity of the HTG states, the absence of a unifying metabolic or genetic abnormality, overlap with the metabolic syndrome and other features of insulin resistance, and evidence in some patients that accumulation of numerous small-effect genetic variants determines whether an individual is susceptible to HTG only or to HTG plus elevated low-density lipoprotein cholesterol, we propose that the diagnosis of primary HTG and further delineation of familial combined hyperlipidemia from familial HTG is neither feasible nor clinically relevant at the present time. The hope is that with greater understanding of genetic and environmental causes and their interaction, therapy can be intelligently targeted in the future.
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Affiliation(s)
- Gary F Lewis
- Departments of Medicine and Physiology and the Banting and Best Diabetes Centre (G.F.L., C.X.), University of Toronto, Toronto, Ontario, Canada M5G 2C4; and Robarts Research Institute (R.A.H.), Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada N6A 5B7
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