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Nurjanah S, Gerding A, Vieira-Lara MA, Evers B, Langelaar-Makkinje M, Spiekerkoetter U, Bakker BM, Tucci S. Heptanoate Improves Compensatory Mechanism of Glucose Homeostasis in Mitochondrial Long-Chain Fatty Acid Oxidation Defect. Nutrients 2023; 15:4689. [PMID: 37960342 PMCID: PMC10649308 DOI: 10.3390/nu15214689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 10/31/2023] [Accepted: 11/01/2023] [Indexed: 11/15/2023] Open
Abstract
Defects in mitochondrial fatty acid β-oxidation (FAO) impair metabolic flexibility, which is an essential process for energy homeostasis. Very-long-chain acyl-CoA dehydrogenase (VLCADD; OMIM 609575) deficiency is the most common long-chain mitochondrial FAO disorder presenting with hypoglycemia as a common clinical manifestation. To prevent hypoglycemia, triheptanoin-a triglyceride composed of three heptanoates (C7) esterified with a glycerol backbone-can be used as a dietary treatment, since it is metabolized into precursors for gluconeogenesis. However, studies investigating the effect of triheptanoin on glucose homeostasis are limited. To understand the role of gluconeogenesis in the pathophysiology of long-chain mitochondrial FAO defects, we injected VLCAD-deficient (VLCAD-/-) mice with 13C3-glycerol in the presence and absence of heptanoate (C7). The incorporation of 13C3-glycerol into blood glucose was higher in VLCAD-/- mice than in WT mice, whereas the difference disappeared in the presence of C7. The result correlates with 13C enrichment of liver metabolites in VLCAD-/- mice. In contrast, the C7 bolus significantly decreased the 13C enrichment. These data suggest that the increased contribution of gluconeogenesis to the overall glucose production in VLCAD-/- mice increases the need for gluconeogenesis substrate, thereby avoiding hypoglycemia. Heptanoate is a suitable substrate to induce glucose production in mitochondrial FAO defect.
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Affiliation(s)
- Siti Nurjanah
- Department of General Pediatrics, Adolescent Medicine and Neonatology, Medical Centre, Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany (U.S.)
- Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Albert Gerding
- Laboratory of Pediatrics, Systems Medicine of Metabolism and Signaling, University Medical Center Groningen, University of Groningen, 9700 RB Groningen, The Netherlands (M.L.-M.)
- Laboratory of Metabolic Diseases, Department of Laboratory Medicine, University Medical Center Groningen, University of Groningen, 9700 RB Groningen, The Netherlands
| | - Marcel A. Vieira-Lara
- Laboratory of Pediatrics, Systems Medicine of Metabolism and Signaling, University Medical Center Groningen, University of Groningen, 9700 RB Groningen, The Netherlands (M.L.-M.)
| | - Bernard Evers
- Laboratory of Pediatrics, Systems Medicine of Metabolism and Signaling, University Medical Center Groningen, University of Groningen, 9700 RB Groningen, The Netherlands (M.L.-M.)
| | - Miriam Langelaar-Makkinje
- Laboratory of Pediatrics, Systems Medicine of Metabolism and Signaling, University Medical Center Groningen, University of Groningen, 9700 RB Groningen, The Netherlands (M.L.-M.)
| | - Ute Spiekerkoetter
- Department of General Pediatrics, Adolescent Medicine and Neonatology, Medical Centre, Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany (U.S.)
| | - Barbara M. Bakker
- Laboratory of Pediatrics, Systems Medicine of Metabolism and Signaling, University Medical Center Groningen, University of Groningen, 9700 RB Groningen, The Netherlands (M.L.-M.)
| | - Sara Tucci
- Pharmacy, Medical Center, University of Freiburg, 79106 Freiburg, Germany
- G.E.R.N. Research Center for Tissue Replacement, Regeneration & Neogenesis, Department of Prosthetic Dentistry, Medical Center, Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany
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2
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Huneault HE, Ramirez Tovar A, Sanchez-Torres C, Welsh JA, Vos MB. The Impact and Burden of Dietary Sugars on the Liver. Hepatol Commun 2023; 7:e0297. [PMID: 37930128 PMCID: PMC10629746 DOI: 10.1097/hc9.0000000000000297] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Accepted: 08/25/2023] [Indexed: 11/07/2023] Open
Abstract
NAFLD, or metabolic dysfunction-associated steatotic liver disease, has increased in prevalence hand in hand with the rise in obesity and increased free sugars in the food supply. The causes of NAFLD are genetic in origin combined with environmental drivers of the disease phenotype. Dietary intake of added sugars has been shown to have a major role in the phenotypic onset and progression of the disease. Simple sugars are key drivers of steatosis, likely through fueling de novo lipogenesis, the conversion of excess carbohydrates into fatty acids, but also appear to upregulate lipogenic metabolism and trigger hyperinsulinemia, another driver. NAFLD carries a clinical burden as it is associated with obesity, type 2 diabetes, metabolic syndrome, and cardiovascular disease. Patient quality of life is also impacted, and there is an enormous economic burden due to healthcare use, which is likely to increase in the coming years. This review aims to discuss the role of dietary sugar in NAFLD pathogenesis, the health and economic burden, and the promising potential of sugar reduction to improve health outcomes for patients with this chronic liver disease.
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Affiliation(s)
- Helaina E. Huneault
- Nutrition and Health Sciences Program, Laney Graduate School, Emory University, Atlanta, Georgia, USA
| | - Ana Ramirez Tovar
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, Emory University, Atlanta, Georgia, USA
| | - Cristian Sanchez-Torres
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, Emory University, Atlanta, Georgia, USA
| | - Jean A. Welsh
- Nutrition and Health Sciences Program, Laney Graduate School, Emory University, Atlanta, Georgia, USA
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, Emory University, Atlanta, Georgia, USA
| | - Miriam B. Vos
- Nutrition and Health Sciences Program, Laney Graduate School, Emory University, Atlanta, Georgia, USA
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, Emory University, Atlanta, Georgia, USA
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Malloy CR, Sherry AD, Alger JR, Jin ES. Recent progress in analysis of intermediary metabolism by ex vivo 13 C NMR. NMR IN BIOMEDICINE 2023; 36:e4817. [PMID: 35997012 DOI: 10.1002/nbm.4817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 08/03/2022] [Accepted: 08/16/2022] [Indexed: 06/15/2023]
Abstract
Advanced imaging technologies, large-scale metabolomics, and the measurement of gene transcripts or enzyme expression all enable investigations of intermediary metabolism in human patients. Complementary information about fluxes in individual metabolic pathways may be obtained by ex vivo 13 C NMR of blood or tissue biopsies. Simple molecules such as 13 C-labeled glucose are readily administered to patients prior to surgical biopsies, and 13 C-labeled glycerol is easily administered orally to outpatients. Here, we review recent progress in practical applications of 13 C NMR to study cancer biology, the response to oxidative stress, gluconeogenesis, triglyceride synthesis in patients, as well as new insights into compartmentation of metabolism in the cytosol. The technical aspects of obtaining the sample, preparing material for analysis, and acquiring the spectra are relatively simple. This approach enables convenient, valuable, and quantitative insights into intermediary metabolism in patients.
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Affiliation(s)
- Craig R Malloy
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Veterans Affairs North Texas Healthcare System, Dallas, Texas, USA
| | - A Dean Sherry
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Chemistry, University of Texas at Dallas, Richardson, Texas, USA
| | - Jeffry R Alger
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Neurology, Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, USA
| | - Eunsook S Jin
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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Dong X, Sun L, Agarwal M, Maker G, Han Y, Yu X, Ren Y. The Effect of Ozone Treatment on Metabolite Profile of Germinating Barley. Foods 2022; 11:foods11091211. [PMID: 35563933 PMCID: PMC9104593 DOI: 10.3390/foods11091211] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 04/11/2022] [Accepted: 04/20/2022] [Indexed: 12/25/2022] Open
Abstract
Ozone is widely used to control pests in grain and impacts seed germination, a crucial stage in crop establishment which involves metabolic alterations. In this study, dormancy was overcome through after-ripening (AR) in dry barley seed storage of more than 4 weeks; alternatively, a 15-min ozone treatment could break the dormancy of barley immediately after harvest, with accelerated germination efficiency remaining around 96% until 4 weeks. Headspace solid-phase microextraction (HS-SPME) and liquid absorption coupled with gas chromatography mass spectrometry (GC-MS) were utilized for metabolite profiling of 2-, 4- and 7-day germinating seeds. Metabolic changes during barley germination are reflected by time-dependent characteristics. Alcohols, fatty acids, and ketones were major contributors to time-driven changes during germination. In addition, greater fatty acids were released at the early germination stage when subjected to ozone treatment.
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Affiliation(s)
- Xue Dong
- College of Science, Health, Engineering and Education, Murdoch University, 90 South Street, Murdoch, Perth 6150, Australia; (X.D.); (L.S.); (M.A.); (G.M.); (Y.H.)
- Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, 50 Zhongling Street, Nanjing 210014, China
| | - Litao Sun
- College of Science, Health, Engineering and Education, Murdoch University, 90 South Street, Murdoch, Perth 6150, Australia; (X.D.); (L.S.); (M.A.); (G.M.); (Y.H.)
| | - Manjree Agarwal
- College of Science, Health, Engineering and Education, Murdoch University, 90 South Street, Murdoch, Perth 6150, Australia; (X.D.); (L.S.); (M.A.); (G.M.); (Y.H.)
| | - Garth Maker
- College of Science, Health, Engineering and Education, Murdoch University, 90 South Street, Murdoch, Perth 6150, Australia; (X.D.); (L.S.); (M.A.); (G.M.); (Y.H.)
| | - Yitao Han
- College of Science, Health, Engineering and Education, Murdoch University, 90 South Street, Murdoch, Perth 6150, Australia; (X.D.); (L.S.); (M.A.); (G.M.); (Y.H.)
| | - Xiangyang Yu
- Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, 50 Zhongling Street, Nanjing 210014, China
- Correspondence: (X.Y.); (Y.R.); Tel.: +86-25-8439-1299 (X.Y.); +618-9360-1397 (Y.R.)
| | - Yonglin Ren
- College of Science, Health, Engineering and Education, Murdoch University, 90 South Street, Murdoch, Perth 6150, Australia; (X.D.); (L.S.); (M.A.); (G.M.); (Y.H.)
- Correspondence: (X.Y.); (Y.R.); Tel.: +86-25-8439-1299 (X.Y.); +618-9360-1397 (Y.R.)
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Iena FM, Jul JB, Vegger JB, Lodberg A, Thomsen JS, Brüel A, Lebeck J. Sex-Specific Effect of High-Fat Diet on Glycerol Metabolism in Murine Adipose Tissue and Liver. Front Endocrinol (Lausanne) 2020; 11:577650. [PMID: 33193093 PMCID: PMC7609944 DOI: 10.3389/fendo.2020.577650] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 09/30/2020] [Indexed: 12/25/2022] Open
Abstract
Obesity is associated with increased plasma glycerol levels. The coordinated regulation of glycerol channels in adipose tissue (AQP7) and the liver (AQP9) has been suggested as an important contributor to the pathophysiology of type-2-diabetes mellitus, as it would provide glycerol for hepatic synthesis of glucose and triglycerides. The regulation of AQP7 and AQP9 is influenced by sex. This study investigates the effect of a high-fat diet (HFD) on glycerol metabolism in mice and the influence of sex and GLP-1-receptor agonist treatment. Female and male C57BL/6JRj mice were fed either a control diet or a HFD for 12 or 24 weeks. Liraglutide was administered (1 mg/kg/day) to a subset of female mice. After 12 weeks of HFD, females had gained less weight than males. In adipose tissue, only females demonstrated an increased abundance of AQP7, whereas only males demonstrated a significant increase in glycerol kinase abundance and adipocyte size. 24 weeks of HFD resulted in a more comparable effect on weight gain and adipose tissue in females and males. HFD resulted in marked hepatic steatosis in males only and had no significant effect on the hepatic abundance of AQP9. Liraglutide treatment generally attenuated the effects of HFD on glycerol metabolism. In conclusion, no coordinated upregulation of glycerol channels in adipose tissue and liver was observed in response to HFD. The effect of HFD on glycerol metabolism is sex-specific in mice, and we propose that the increased AQP7 abundance in female adipose tissue could contribute to their less severe response to HFD.
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Behn CD, Bubar K, Jin ES, Malloy CR, Parks EJ, Cree-Green M. Advances in stable isotope tracer methodology part 1: hepatic metabolism via isotopomer analysis and postprandial lipolysis modeling. J Investig Med 2020; 68:3-10. [PMID: 31554675 PMCID: PMC7372575 DOI: 10.1136/jim-2019-001109] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/10/2019] [Indexed: 01/02/2023]
Abstract
Stable isotope tracers have been used to gain an understanding of integrative animal and human physiology. More commonly studied organ systems include hepatic glucose metabolism, lipolysis from adipose tissue, and whole body protein metabolism. Recent improvements in isotope methodology have included the use of novel physiologic methods/models and mathematical modeling of data during different physiologic states. Here we review some of the latest advancements in this field and highlight future research needs. First we discuss the use of an oral [U-13C3]-glycerol tracer to determine the relative contribution of glycerol carbons to hepatic glucose production after first cycling through the tricarboxylic acid cycle, entry of glycerol into the pentose phosphate pathway or direct conversion of glycerol into the glucose. Second, we describe an adaptation of the established oral minimal model used to define postprandial glucose dynamics to include glycerol dynamics in an oral glucose tolerance test with a [2H5]-glycerol tracer to determine dynamic changes in lipolysis. Simulation results were optimized when parameters describing glycerol flux were determined with a hybrid approach using both tracer-based calculations and constrained parameter optimization. Both of these methodologies can be used to expand our knowledge of not only human physiology, but also the effects of various nutritional strategies and medications on metabolism.
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Affiliation(s)
- Cecilia Diniz Behn
- Department of Applied Mathematics and Statistics, Colorado School of Mines, Golden, CO, USA
- Department of Pediatrics, Division of Pediatric Endocrinology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Kate Bubar
- Department of Applied Mathematics and Statistics, Colorado School of Mines, Golden, CO, USA
| | - Eunsook S. Jin
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Craig R. Malloy
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Elizabeth J. Parks
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, MO, USA
| | - Melanie Cree-Green
- Department of Pediatrics, Division of Pediatric Endocrinology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
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Van Anh TN, Hao TK, Chi NTD, Son NH. Predictions of Hypoxic-Ischemic Encephalopathy by Umbilical Cord Blood Lactate in Newborns with Birth Asphyxia. Open Access Maced J Med Sci 2019; 7:3564-3567. [PMID: 32010377 PMCID: PMC6986534 DOI: 10.3889/oamjms.2019.581] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Revised: 09/04/2019] [Accepted: 09/05/2019] [Indexed: 12/02/2022] Open
Abstract
AIM: The aim of the study was to investigate the role of umbilical cord blood lactate as early predictors of hypoxic ischemic encephalopathy in newborns with perinatal asphyxia and to evaluate their sensitivity and specificity for the early identification of hypoxic ischemic encephalopathy infants. METHODS: We performed a descriptive cross sectional study between April 2014 and April 2015 at Hue Central Hospital, Vietnam. 41 asphyxia newborns (Apgar score ≤ 7) were included in the study. Umbilical cord blood is sampled for lactate analysis. RESULTS: Umbilical cord blood lactate levels were significantly higher among infants born with HIE (mean 8.72 ± 1.75, range 5.12 – 11.96) compared to that with asphyxic infants without HIE (mean 6.86 ± 1.33, range 4.74 – 10.30), p = 0.00. With the optimal cutoff point for umbilical cord blood lactate level of 8.12 mmol/l to susspected of HIE (area under the curve 0.799) had a sensitivity 73.7% (95% CI 48.8-90.9), specificity 86.4% (95% CI 65.1-97.1). CONCLUSION: Umbilical cord blood lactate could be used as early predictors in diagnosis of hypoxic ischemic encephalopathy in newborns with asphyxia.
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Affiliation(s)
- Ton Nu Van Anh
- Pediatric Department, Hue University of Medicine and Pharmacy, Hue University, Hue, Vietnam
| | - Tran Kiem Hao
- Pediatric Center, Hue Central Hospital, Hue, Vietnam
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Wolfe RR, Park S, Kim IY, Moughan PJ, Ferrando AA. Advances in stable isotope tracer methodology part 2: new thoughts about an “old” method—measurement of whole body protein synthesis and breakdown in the fed state. J Investig Med 2019; 68:11-15. [DOI: 10.1136/jim-2019-001108] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/01/2019] [Indexed: 11/03/2022]
Abstract
Whole-body protein turnover (protein synthesis, breakdown, and net balance) model enables quantification of the response to a variety of circumstances, including the response to meal feeding. In the fed state, the whole-body protein turnover model requires taking account of the contribution of absorbed tracee to the observed total appearance of tracee in the peripheral blood (exogenous appearance, RaEXO). There are different approaches to estimating RaEXO. The use of an intrinsically labeled dietary protein is based on the overriding assumption that the appearance in the peripheral circulation of a tracer amino acid incorporated into a dietary protein is exactly proportional to the appearance of absorbed tracee. The bioavailability approach is based on the true ileal digestibility of the dietary protein and the irreversible loss of the tracee in the splanchnic bed via hydroxylation of the tracee (phenylalanine). Finally, RaEXO can be estimated as the increase above the basal rate of appearance of the tracee using traditional tracer dilution methodology. In this paper, we discuss the pros and cons of each approach and conclude that the bioavailability method is the least likely to introduce systematic errors and is therefore the preferable approach.
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Maessen GC, Wijnhoven AM, Neijzen RL, Paulus MC, van Heel DAM, Bomers BHA, Boersma LE, Konya B, van der Heyden MAG. Nicotine intoxication by e-cigarette liquids: a study of case reports and pathophysiology. Clin Toxicol (Phila) 2019; 58:1-8. [PMID: 31286797 DOI: 10.1080/15563650.2019.1636994] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Background: Electronic cigarettes (e-cigarettes), the smokeless alternative to conventional tobacco cigarettes, have become increasingly popular. E-cigarettes vaporise e-liquid, a solution of highly concentrated nicotine, propylene glycol (PG) and vegetable glycerine (VG). With the popularity of e-cigarettes, e-liquid refills have become easily accessible and several cases of intoxication due to the ingestion of e-liquid have been reported. We provide an overview of these cases, their pathophysiology and patients' characteristics.Methods: We carried out a retrospective evaluation of the scientific literature reporting on cases of liquid nicotine intoxication, using the following inclusion criteria: (1) the article is or contains a case report, (2) describes an intoxication with e-liquid, (3) the substance contains nicotine, and (4) intake is oral, intravenous or subcutaneous.Results: We found 26 case reports describing a total of 31 patients who suffered from e-liquid intoxication. All intoxications up to the age of six were reported as unintentional, whereas nearly all cases from ages 13 to 53 were due to suicide attempts. The three most prevalent symptoms of e-liquid intoxication were tachycardia, altered mental status and vomiting. Eleven cases resulted in the death of the patient. In the survivors, the highest plasma concentration of nicotine was 800 µg L-1, while the lowest concentration in the non-survivors was 1600 µg L-1.Conclusions: There is a mismatch between the generally accepted lethal oral nicotine dose of 60 mg, resulting in approximately 180 µg L-1 plasma concentration, and the 4.4- to 8.9-fold higher lethal plasma concentrations we found in cases of e-liquid intoxication. In these severe intoxications, plasma cotinine concentration does not act as a more reliable indicator of nicotine intoxication than nicotine itself. The ages of the patients display a bimodal distribution. In patients above the age of 10, intoxication results mainly from suicide attempts rather than accidental ingestion. The role of PG and VG in e-liquid intoxications is remarkably unclear. However, the similarity across nicotine and PG toxicity symptoms leads us to believe a cumulative effect cannot be excluded.
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Affiliation(s)
- Gerdinique C Maessen
- Honours Program CRU + Bachelor, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Anjali M Wijnhoven
- Honours Program CRU + Bachelor, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Rosalie L Neijzen
- Honours Program CRU + Bachelor, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Michelle C Paulus
- Honours Program CRU + Bachelor, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Dayna A M van Heel
- Honours Program CRU + Bachelor, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Bart H A Bomers
- Honours Program CRU + Bachelor, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Lucie E Boersma
- Honours Program CRU + Bachelor, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Burak Konya
- Honours Program CRU + Bachelor, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Marcel A G van der Heyden
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
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Fast LC-MS quantitation of glucose and glycerol via enzymatic derivatization. Anal Biochem 2019; 575:40-43. [PMID: 30940446 DOI: 10.1016/j.ab.2019.03.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 03/26/2019] [Accepted: 03/27/2019] [Indexed: 11/21/2022]
Abstract
Glucose and glycerol are important circulating metabolites. Due to poor ionization and/or ion suppression, the liquid chromatography-mass spectrometry (LC-MS) detection of glucose and glycerol presents challenges. Here, we propose an efficient LC-MS method of quantitative glucose and glycerol detection via enzymatic derivatization to glucose-6-phosphate and sn-glycerol-3-phosphate, respectively. This derivatization protocol can be used to measure the concentrations of glucose production in a plethora of sample types for metabolic analysis and is compatible with the general metabolomics workflow. This novel approach allows us to quantitatively study glucose and glycerol metabolism using stable isotope tracers in vivo.
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Döring S, Seeßle J, Gan-Schreier H, Javaheri B, Jiao L, Cheng Y, Tuma-Kellner S, Liebisch G, Herrmann T, Stremmel W, Chamulitrat W. Elevation of blood lipids in hepatocyte-specific fatty acid transport 4-deficient mice fed with high glucose diets. Mol Genet Metab 2019; 126:30-38. [PMID: 30497809 DOI: 10.1016/j.ymgme.2018.11.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 11/12/2018] [Accepted: 11/17/2018] [Indexed: 11/20/2022]
Abstract
Fatty acid transport protein4 (FATP4) is upregulated in acquired and central obesity and its polymorphisms are associated with blood lipids and insulin resistance. Patients with FATP4 mutations and mice with global FATP4 deletion exhibit skin abnormalities characterized as ischthyosis prematurity syndrome (IPS). Cumulating data have shown that an absence of FATP4 increases the levels of cellular triglycerides (TG). However, FATP4 role and consequent lipid and TG metabolism in the hepatocyte is still elusive. Here, hepatocyte-specific FATP4 deficient (Fatp4L-/-) mice were generated. When fed with chow, these mutant mice displayed no phenotypes regarding blood lipids. However when fed low-fat/high-sugar (HS) or high-fat/high-sugar (HFS) for 12 weeks, Fatp4L-/- mice showed a significant increase of plasma TG, free fatty acids and glycerol when compared with diet-fed control mice. Interestingly, Fatp4L-/- mice under HS diet had lower body and liver weights and they were not protected from HFS-induced body weight gain and hepatic steatosis. Male mutant mice were more sensitive to HFS diet than female mutant mice. Glucose intolerance was observed only in female Fatp4L-/- mice fed with HS diet. Lipidomics analyses revealed that hepatic phospholipids were not disturbed in mutant mice under both diets. Thus, hepatic FATP4 deletion rendered an increase of blood lipids including glycerol indicating a preferential fatty-acid channeling to TG pools that are specifically available for lipolysis. Our results imply a possible risk of hyperlipidemia as a result of abnormal metabolism in liver in IPS patients with FATP4 mutations who consume high-sugar diets.
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Affiliation(s)
- Stephan Döring
- Department of Internal Medicine IV, University of Heidelberg Hospital, Im Neuenheimer Feld 410, 69120 Heidelberg, Germany
| | - Jessica Seeßle
- Department of Internal Medicine IV, University of Heidelberg Hospital, Im Neuenheimer Feld 410, 69120 Heidelberg, Germany
| | - Hongying Gan-Schreier
- Department of Internal Medicine IV, University of Heidelberg Hospital, Im Neuenheimer Feld 410, 69120 Heidelberg, Germany
| | - Bahador Javaheri
- Department of Internal Medicine IV, University of Heidelberg Hospital, Im Neuenheimer Feld 410, 69120 Heidelberg, Germany
| | - Li Jiao
- Institute of Medical Biology, Chinese Academy of Medical Sciences, Peking Union Medical College, Kunming, Yunnan 650118, China
| | - Yuting Cheng
- Department of Internal Medicine IV, University of Heidelberg Hospital, Im Neuenheimer Feld 410, 69120 Heidelberg, Germany
| | - Sabine Tuma-Kellner
- Department of Internal Medicine IV, University of Heidelberg Hospital, Im Neuenheimer Feld 410, 69120 Heidelberg, Germany
| | - Gerhard Liebisch
- Institute of Clinical Chemistry and Laboratory Medicine, University of Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany
| | - Thomas Herrmann
- Westkuesten Hospital, Esmarchstraße 50, 25746 Heide, Germany
| | - Wolfgang Stremmel
- Department of Internal Medicine IV, University of Heidelberg Hospital, Im Neuenheimer Feld 410, 69120 Heidelberg, Germany
| | - Walee Chamulitrat
- Department of Internal Medicine IV, University of Heidelberg Hospital, Im Neuenheimer Feld 410, 69120 Heidelberg, Germany.
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12
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Sørensen LB, Gazerani P, Wåhlén K, Ghafouri N, Gerdle B, Ghafouri B. Investigation of biomarkers alterations after an acute tissue trauma in human trapezius muscle, using microdialysis. Sci Rep 2018; 8:3034. [PMID: 29445230 PMCID: PMC5813028 DOI: 10.1038/s41598-018-21185-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Accepted: 01/30/2018] [Indexed: 02/08/2023] Open
Abstract
Alterations in muscle milieu are suggested as important activity of peripheral drive in patients with chronic musculoskeletal pain (CMP). Microdialysis (MD) has been used in monitoring altered metabolic response pattern in muscles. However, the insertion of MD probe causes a local tissue trauma. Whether and how metabolites in trapezius muscle are affected by acute tissue trauma is unknown. Hence, this study investigated the metabolic response and nociceptive reaction of the tissue following MD probe insertion in patients with CMP and healthy individuals. Fifty-nine patients and forty pain-free volunteers were recruited. Pressure pain thresholds (PPTs) were obtained at the trapezius and tibialis muscles. Pain questionnaires determined the levels of pain related aspects. MD (20 kDa cut-off) was performed in the trapezius and samples were collected within 40 min. Interstitial concentration of the metabolites was analyzed by a two-way-mixed-ANOVA. The metabolic response pattern changed over time and alterations in the level of metabolites could be seen in both CMP and healthy controls. Pain questionnaires and pain intensities manifested clinical aspects of pain closely to what CMP patients describe. Analyzing metabolites due to acute tissue trauma by aid of MD may be a useful model to investigate altered metabolic response effect in CMP.
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Affiliation(s)
- Line Bay Sørensen
- Center for Neuroplasticity and Pain (CNAP), SMI®, Department of Health Science and Technology, School of Medicine and Health, Aalborg University, Aalborg, Denmark.
| | - Parisa Gazerani
- Center for Neuroplasticity and Pain (CNAP), SMI®, Department of Health Science and Technology, School of Medicine and Health, Aalborg University, Aalborg, Denmark
| | - Karin Wåhlén
- Pain and Rehabilitation Centre, and Department of Medical and Health Sciences, Linköping University, Linköping, Sweden
| | - Nazdar Ghafouri
- Pain and Rehabilitation Centre, and Department of Medical and Health Sciences, Linköping University, Linköping, Sweden
| | - Björn Gerdle
- Pain and Rehabilitation Centre, and Department of Medical and Health Sciences, Linköping University, Linköping, Sweden
| | - Bijar Ghafouri
- Pain and Rehabilitation Centre, and Department of Medical and Health Sciences, Linköping University, Linköping, Sweden
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13
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Li J, Zhang ZZ, Lei ZH, Qin XM, Li ZY. NMR based metabolomic comparison of the antitussive and expectorant effect of Farfarae Flos collected at different stages. J Pharm Biomed Anal 2018; 150:377-385. [DOI: 10.1016/j.jpba.2017.12.028] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 12/11/2017] [Accepted: 12/12/2017] [Indexed: 01/28/2023]
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14
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Daurio NA, Wang SP, Chen Y, Zhou H, McLaren DG, Roddy TP, Johns DG, Milot D, Kasumov T, Erion MD, Kelley DE, Previs SF. Enhancing Studies of Pharmacodynamic Mechanisms via Measurements of Metabolic Flux: Fundamental Concepts and Guiding Principles for Using Stable Isotope Tracers. J Pharmacol Exp Ther 2017; 363:80-91. [DOI: 10.1124/jpet.117.241091] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2017] [Accepted: 06/14/2017] [Indexed: 11/22/2022] Open
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15
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Valette J, Tiret B, Boumezbeur F. Experimental strategies for in vivo 13C NMR spectroscopy. Anal Biochem 2016; 529:216-228. [PMID: 27515993 DOI: 10.1016/j.ab.2016.08.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 05/24/2016] [Accepted: 08/04/2016] [Indexed: 11/15/2022]
Abstract
In vivo carbon-13 (13C) MRS opens unique insights into the metabolism of intact organisms, and has led to major advancements in the understanding of cellular metabolism under normal and pathological conditions in various organs such as skeletal muscles, the heart, the liver and the brain. However, the technique comes at the expense of significant experimental difficulties. In this review we focus on the experimental aspects of non-hyperpolarized 13C MRS in vivo. Some of the enrichment strategies which have been proposed so far are described; the various MRS acquisition paradigms to measure 13C labeling are then presented. Finally, practical aspects of 13C spectral quantification are discussed.
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Affiliation(s)
- Julien Valette
- Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Direction de la Recherche Fondamentale (DRF), Institut d'Imagerie Biomédicale (I2BM), MIRCen, F-92260 Fontenay-aux-Roses, France; Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud, Université Paris-Saclay, UMR 9199, Neurodegenerative Diseases Laboratory, F-92260 Fontenay-aux-Roses, France.
| | - Brice Tiret
- Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Direction de la Recherche Fondamentale (DRF), Institut d'Imagerie Biomédicale (I2BM), MIRCen, F-92260 Fontenay-aux-Roses, France; Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud, Université Paris-Saclay, UMR 9199, Neurodegenerative Diseases Laboratory, F-92260 Fontenay-aux-Roses, France
| | - Fawzi Boumezbeur
- Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Direction de la Recherche Fondamentale (DRF), Institut d'Imagerie Biomédicale (I2BM), NeuroSpin, F-91190 Gif-sur-Yvette, France
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16
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Jin ES, Sherry AD, Malloy CR. An Oral Load of [13C3]Glycerol and Blood NMR Analysis Detect Fatty Acid Esterification, Pentose Phosphate Pathway, and Glycerol Metabolism through the Tricarboxylic Acid Cycle in Human Liver. J Biol Chem 2016; 291:19031-41. [PMID: 27432878 DOI: 10.1074/jbc.m116.742262] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Indexed: 11/06/2022] Open
Abstract
Drugs and other interventions for high impact hepatic diseases often target biochemical pathways such as gluconeogenesis, lipogenesis, or the metabolic response to oxidative stress. However, traditional liver function tests do not provide quantitative data about these pathways. In this study, we developed a simple method to evaluate these processes by NMR analysis of plasma metabolites. Healthy subjects ingested [U-(13)C3]glycerol, and blood was drawn at multiple times. Each subject completed three visits under differing nutritional states. High resolution (13)C NMR spectra of plasma triacylglycerols and glucose provided new insights into a number of hepatic processes including fatty acid esterification, the pentose phosphate pathway, and gluconeogenesis through the tricarboxylic acid cycle. Fasting stimulated pentose phosphate pathway activity and metabolism of [U-(13)C3]glycerol in the tricarboxylic acid cycle prior to gluconeogenesis or glyceroneogenesis. Fatty acid esterification was transient in the fasted state but continuous under fed conditions. We conclude that a simple NMR analysis of blood metabolites provides an important biomarker of pentose phosphate pathway activity, triacylglycerol synthesis, and flux through anaplerotic pathways in mitochondria of human liver.
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Affiliation(s)
- Eunsook S Jin
- From the Advanced Imaging Research Center and the Departments of Internal Medicine and
| | - A Dean Sherry
- From the Advanced Imaging Research Center and Radiology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390, the Department of Chemistry, University of Texas at Dallas, Richardson, Texas 75080, and
| | - Craig R Malloy
- From the Advanced Imaging Research Center and the Departments of Internal Medicine and Radiology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390, the VA North Texas Health Care System, Dallas, Texas 75216
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17
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Jin ES, Sherry AD, Malloy CR. Lactate Contributes to Glyceroneogenesis and Glyconeogenesis in Skeletal Muscle by Reversal of Pyruvate Kinase. J Biol Chem 2015; 290:30486-97. [PMID: 26491014 DOI: 10.1074/jbc.m115.689174] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Indexed: 11/06/2022] Open
Abstract
Phosphoenolpyruvate (PEP) generated from pyruvate is required for de novo synthesis of glycerol and glycogen in skeletal muscle. One possible pathway involves synthesis of PEP from the citric acid cycle intermediates via PEP carboxykinase, whereas another could involve reversal of pyruvate kinase (PK). Earlier studies have reported that reverse flux through PK can contribute carbon precursors for glycogen synthesis in muscle, but the physiological importance of this pathway remains uncertain especially in the setting of high plasma glucose. In addition, although PEP is a common intermediate for both glyconeogenesis and glyceroneogenesis, the importance of reverse PK in de novo glycerol synthesis has not been examined. Here we studied the contribution of reverse PK to synthesis of glycogen and the glycerol moiety of acylglycerols in skeletal muscle of animals with high plasma glucose. Rats received a single intraperitoneal bolus of glucose, glycerol, and lactate under a fed or fasted state. Only one of the three substrates was (13)C-labeled in each experiment. After 3 h of normal awake activity, the animals were sacrificed, and the contribution from each substrate to glycogen and the glycerol moiety of acylglycerols was evaluated. The fraction of (13)C labeling in glycogen and the glycerol moiety exceeded the possible contribution from either plasma glucose or muscle oxaloacetate. The reverse PK served as a common route for both glyconeogenesis and glyceroneogenesis in the skeletal muscle of rats with high plasma glucose. The activity of pyruvate carboxylase was low in muscle, and no PEP carboxykinase activity was detected.
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Affiliation(s)
- Eunsook S Jin
- From the Advanced Imaging Research Center, Department of Internal Medicine, and
| | - A Dean Sherry
- From the Advanced Imaging Research Center, Radiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, Department of Chemistry, University of Texas at Dallas, Richardson, Texas 75080, and
| | - Craig R Malloy
- From the Advanced Imaging Research Center, Department of Internal Medicine, and Radiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, Veterans Affairs North Texas Health Care System, Dallas, Texas 75216
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18
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Bartok O, Teesalu M, Ashwall-Fluss R, Pandey V, Hanan M, Rovenko BM, Poukkula M, Havula E, Moussaieff A, Vodala S, Nahmias Y, Kadener S, Hietakangas V. The transcription factor Cabut coordinates energy metabolism and the circadian clock in response to sugar sensing. EMBO J 2015; 34:1538-53. [PMID: 25916830 DOI: 10.15252/embj.201591385] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 04/01/2015] [Indexed: 12/16/2022] Open
Abstract
Nutrient sensing pathways adjust metabolism and physiological functions in response to food intake. For example, sugar feeding promotes lipogenesis by activating glycolytic and lipogenic genes through the Mondo/ChREBP-Mlx transcription factor complex. Concomitantly, other metabolic routes are inhibited, but the mechanisms of transcriptional repression upon sugar sensing have remained elusive. Here, we characterize cabut (cbt), a transcription factor responsible for the repressive branch of the sugar sensing transcriptional network in Drosophila. We demonstrate that cbt is rapidly induced upon sugar feeding through direct regulation by Mondo-Mlx. We found that CBT represses several metabolic targets in response to sugar feeding, including both isoforms of phosphoenolpyruvate carboxykinase (pepck). Deregulation of pepck1 (CG17725) in mlx mutants underlies imbalance of glycerol and glucose metabolism as well as developmental lethality. Furthermore, we demonstrate that cbt provides a regulatory link between nutrient sensing and the circadian clock. Specifically, we show that a subset of genes regulated by the circadian clock are also targets of CBT. Moreover, perturbation of CBT levels leads to deregulation of the circadian transcriptome and circadian behavioral patterns.
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Affiliation(s)
- Osnat Bartok
- Biological Chemistry Department, Silberman Institute of Life Sciences The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Mari Teesalu
- Department of Biosciences, University of Helsinki, Helsinki, Finland Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Reut Ashwall-Fluss
- Biological Chemistry Department, Silberman Institute of Life Sciences The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Varun Pandey
- Biological Chemistry Department, Silberman Institute of Life Sciences The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Mor Hanan
- Biological Chemistry Department, Silberman Institute of Life Sciences The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Bohdana M Rovenko
- Department of Biosciences, University of Helsinki, Helsinki, Finland Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Minna Poukkula
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Essi Havula
- Department of Biosciences, University of Helsinki, Helsinki, Finland Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Arieh Moussaieff
- Department of Cell Biology, Silberman Institute of Life Sciences The Hebrew University of Jerusalem, Jerusalem, Israel Center for Bioengineering, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Sadanand Vodala
- Howard Hughes Medical Institute, Brandeis University, Waltham, MA, USA
| | - Yaakov Nahmias
- Department of Cell Biology, Silberman Institute of Life Sciences The Hebrew University of Jerusalem, Jerusalem, Israel Center for Bioengineering, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Sebastian Kadener
- Biological Chemistry Department, Silberman Institute of Life Sciences The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Ville Hietakangas
- Department of Biosciences, University of Helsinki, Helsinki, Finland Institute of Biotechnology, University of Helsinki, Helsinki, Finland
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19
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Cowens KR, Simpson S, Thomas WK, Carey GB. Polybrominated Diphenyl Ether (PBDE)-Induced Suppression of Phosphoenolpyruvate Carboxykinase (PEPCK) Decreases Hepatic Glyceroneogenesis and Disrupts Hepatic Lipid Homeostasis. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2015; 78:1437-49. [PMID: 26692069 DOI: 10.1080/15287394.2015.1098580] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Polybrominated diphenyl ethers (PBDE) are a class of flame-retardant chemicals that leach into the environment and enter the human body. PBDE have been shown to suppress activity of phosphoenolpyruvate carboxykinase (PEPCK), a key enzyme in fatty acid esterification via hepatic glyceroneogenesis. The objective of this investigation was to assess hepatic glyceroneogenesis and lipid metabolism in PBDE-treated rats. Male, weanling Wistar rats were gavaged daily for 28 d with 14 mg/kg body weight of either DE-71, a commercial PBDE mixture (treated), or corn oil (control). After a 48-h fast, rats were euthanized, blood was obtained, and livers were excised. Suppression of hepatic PEPCK activity by 40% was noted. Serum ketone bodies were elevated by 27% in treated rats compared to controls, while hepatic glyceroneogenesis as measured by (14)C-pyruvate incorporation into triglycerides was 41% lower in explants from treated rats compared to controls. Liver lipid content was 29% lower in treated animals compared to controls. Taken together, these findings suggest that DE-71-induced inhibition of hepatic PEPCK activity alters lipid metabolism by redirecting fatty acids away from esterification and storage toward ketone synthesis.
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Affiliation(s)
- Kylie R Cowens
- a Department of Molecular, Cellular, and Biomedical Sciences , University of New Hampshire , Durham , New Hampshire , USA
| | - Stephen Simpson
- a Department of Molecular, Cellular, and Biomedical Sciences , University of New Hampshire , Durham , New Hampshire , USA
| | - W Kelley Thomas
- a Department of Molecular, Cellular, and Biomedical Sciences , University of New Hampshire , Durham , New Hampshire , USA
| | - Gale B Carey
- a Department of Molecular, Cellular, and Biomedical Sciences , University of New Hampshire , Durham , New Hampshire , USA
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20
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Jin ES, Sherry AD, Malloy CR. Interaction between the pentose phosphate pathway and gluconeogenesis from glycerol in the liver. J Biol Chem 2014; 289:32593-603. [PMID: 25288790 DOI: 10.1074/jbc.m114.577692] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
After exposure to [U-(13)C3]glycerol, the liver produces primarily [1,2,3-(13)C3]- and [4,5,6-(13)C3]glucose in equal proportions through gluconeogenesis from the level of trioses. Other (13)C-labeling patterns occur as a consequence of alternative pathways for glucose production. The pentose phosphate pathway (PPP), metabolism in the citric acid cycle, incomplete equilibration by triose phosphate isomerase, or the transaldolase reaction all interact to produce complex (13)C-labeling patterns in exported glucose. Here, we investigated (13)C labeling in plasma glucose in rats given [U-(13)C3]glycerol under various nutritional conditions. Blood was drawn at multiple time points to extract glucose for NMR analysis. Because the transaldolase reaction and incomplete equilibrium by triose phosphate isomerase cannot break a (13)C-(13)C bond within the trioses contributing to glucose, the appearance of [1,2-(13)C2]-, [2,3-(13)C2]-, [5,6-(13)C2]-, and [4,5-(13)C2]glucose provides direct evidence for metabolism of glycerol in the citric acid cycle or the PPP but not an influence of either triose phosphate isomerase or the transaldolase reaction. In all animals, [1,2-(13)C2]glucose/[2,3-(13)C2]glucose was significantly greater than [5,6-(13)C2]glucose/[4,5-(13)C2]glucose, a relationship that can only arise from gluconeogenesis followed by passage of substrates through the PPP. In summary, the hepatic PPP in vivo can be detected by (13)C distribution in blood glucose after [U-(13)C3]glycerol administration.
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Affiliation(s)
- Eunsook S Jin
- From the Advanced Imaging Research Center and Departments of Internal Medicine and
| | - A Dean Sherry
- From the Advanced Imaging Research Center and Radiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, the Department of Chemistry, University of Texas at Dallas, Richardson, Texas 75080, and
| | - Craig R Malloy
- From the Advanced Imaging Research Center and Departments of Internal Medicine and Radiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, the Veterans Affairs North Texas Health Care System, Dallas, Texas 75216
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