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Patel JV, Tracey I, Hughes EA, Lip GYH. Unraveling the paradoxical link between obesity and heart failure: the role of adipocytokines. Expert Rev Cardiovasc Ther 2009; 7:337-40. [DOI: 10.1586/erc.09.12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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252
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Abstract
PURPOSE OF REVIEW To summarize recent studies that shed more light on possible mechanisms by which ectopic lipid storage affects organ function. RECENT FINDINGS Although ectopic lipids have been considered as biomarkers of lipotoxicity, adaptation of metabolic fluxes and of mitochondrial function seem to be more important than actual cellular fat contents in liver and muscle. Diabetic and obese humans have elevated myocardial lipid contents, which are associated with mitochondrial and contractile dysfunction and could even precede the development of heart failure. Although pancreatic fat content is negatively associated with insulin secretion, [beta]-cell triglycerides are not easily accessible to measurement in humans rendering their role for [beta]-cell function unclear. New approaches to quantify energy metabolism in various organs could help to identify novel biomarkers of organ function in humans. SUMMARY Dietary intake of high-caloric high-fat diets and sedentary lifestyle lead to increased storage of triglycerides not only in adipose tissue but also ectopically in other tissues. Intracellular lipid contents in skeletal muscle and liver have been related to insulin resistance and inflammatory processes. Myocardial fat is increased in heart failure, whereas pancreatic fat could relate to insulin secretion.
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Affiliation(s)
- Julia Szendroedi
- Department of Medicine/Metabolic Diseases, Institute for Clinical Diabetology, German Diabetes Center, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
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Brookheart RT, Michel CI, Listenberger LL, Ory DS, Schaffer JE. The non-coding RNA gadd7 is a regulator of lipid-induced oxidative and endoplasmic reticulum stress. J Biol Chem 2009; 284:7446-54. [PMID: 19150982 DOI: 10.1074/jbc.m806209200] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
In obesity and diabetes, an imbalance in fatty acid uptake and fatty acid utilization leads to excess accumulation of lipid in non-adipose tissues. This lipid overload is associated with cellular dysfunction and cell death, which contribute to organ failure, a phenomenon termed lipotoxicity. To elucidate the molecular mechanism of lipid-mediated cell death, we generated and characterized a mutant Chinese hamster ovary cell line that is resistant to palmitate-induced cell death. In this mutant, random insertion of a retroviral promoter trap has disrupted the gene for the non-coding RNA, growth arrested DNA-damage inducible gene 7 (gadd7). Here we report that gadd7 is induced by lipotoxic stress in a reactive oxygen species (ROS)-dependent fashion and is necessary for both lipid- and general oxidative stress-mediated cell death. Depletion of gadd7 by mutagenesis or short hairpin RNA knockdown significantly reduces lipid and non-lipid induced ROS. Furthermore, depletion of gadd7 delays and diminishes ROS-induced endoplasmic reticulum stress. Together these data are the first to implicate a non-coding RNA in a feed-forward loop with oxidative stress and its induction of the endoplasmic reticulum stress response.
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Affiliation(s)
- Rita T Brookheart
- Center for Cardiovascular Research, Department of Internal Medicine, the Department of Cell Biology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Thomas MA, Lipnick S, Velan SS, Liu X, Banakar S, Binesh N, Ramadan S, Ambrosio A, Raylman RR, Sayre J, DeBruhl N, Bassett L. Investigation of breast cancer using two-dimensional MRS. NMR IN BIOMEDICINE 2009; 22:77-91. [PMID: 19086016 DOI: 10.1002/nbm.1310] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Proton (1H) MRS enables non-invasive biochemical assay with the potential to characterize malignant, benign and healthy breast tissues. In vitro studies using perchloric acid extracts and ex vivo magic angle spinning spectroscopy of intact biopsy tissues have been used to identify detectable metabolic alterations in breast cancer. The challenges of 1H MRS in vivo include low sensitivity and significant overlap of resonances due to limited chemical shift dispersion and significant inhomogeneous broadening at most clinical magnetic field strengths. Improvement in spectral resolution can be achieved in vivo and in vitro by recording the MR spectra spread over more than one dimension, thus facilitating unambiguous assignment of metabolite and lipid resonances in breast cancer. This article reviews the recent progress with two-dimensional MRS of breast cancer in vitro, ex vivo and in vivo. The discussion includes unambiguous detection of saturated and unsaturated fatty acids, as well as choline-containing groups such as free choline, phosphocholine, glycerophosphocholine and ethanolamines using two-dimensional MRS. In addition, characterization of invasive ductal carcinomas and healthy fatty/glandular breast tissues non-invasively using the classification and regression tree (CART) analysis of two-dimensional MRS data is reviewed.
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Affiliation(s)
- M Albert Thomas
- Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, CA 90095-1721, USA.
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McGuire DK, See R, Abdullah SM, Snell PG, McGavock JM, Ayers CR, Szczepaniak LS. The effect of rosiglitazone on integrated cardiovascular performance, cardiac structure, function and myocardial triglyceride: trial design and rationale. Diab Vasc Dis Res 2009; 6:43-50. [PMID: 19156629 DOI: 10.3132/dvdr.2009.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The thiazolidinedione (TZD) class of medications has been associated with increased risk for peripheral oedema, as well as incident and worsening heart failure (HF). The mechanism of these observed effects remains unclear. Here we present the rationale and study design for a randomised clinical trial designed to evaluate the cardiac effects of rosiglitazone on integrated cardiovascular performance, cardiac structure and function. The study is a randomised, single-centre, double-blind, placebo-controlled, parallel-group clinical trial to evaluate the effect of rosiglitazone on integrated cardiovascular performance in a cohort of patients with type 2 diabetes mellitus (T2DM) at increased risk for developing heart failure (HF). Participants will be randomised to receive rosiglitazone or matching placebo for six months. All subjects will undergo maximal treadmill cardiopulmonary exercise testing at baseline and after six months on study drug, with the primary trial end point of peak oxygen uptake indexed to fat-free mass (VO 2peak-FFM). Approximately two-thirds of the study cohort will undergo cardiac magnetic resonance imaging (MRI) and spectroscopy (MRS) at baseline and after six months of study therapy to assess cardiac structure, function and myocardial triglyceride content. While concerns for peripheral oedema and HF continue to confound clinical use of TZD medications, the direct cardiac effects of these drugs remain poorly understood and the clinical relevance of these clinical observations remains unclear. The present study will combine a series of state-of-the-art assessments to evaluate the cardiac effects of rosiglitazone treatment.
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Affiliation(s)
- Darren K McGuire
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75235-9047, USA.
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256
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Abstract
Over the past 10 years, major progress has been made in the pathogenesis of uric acid and calcium stones. These advances have led to our further understanding of a pathogenetic link between uric acid nephrolithiasis and the metabolic syndrome, the role of Oxalobacter formigenes in calcium oxalate stone formation, oxalate transport in Slc26a6-null mice, the potential pathogenetic role of Randall's plaque as a precursor for calcium oxalate nephrolithiasis, and the role of renal tubular crystal retention. With these advances, we may target the development of novel drugs including (1) insulin sensitizers; (2) probiotic therapy with O. formigenes, recombinant enzymes, or engineered bacteria; (3) treatments that involve the upregulation of intestinal luminal oxalate secretion by increasing anion transporter activity (Slc26a6), luminally active nonabsorbed agents, or oxalate binders; and (4) drugs that prevent the formation of Randall's plaque and/or renal tubular crystal adhesions.
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Affiliation(s)
- Khashayar Sakhaee
- Department of Internal Medicine, Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390-8885, USA.
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Hammer S, Snel M, Lamb HJ, Jazet IM, van der Meer RW, Pijl H, Meinders EA, Romijn JA, de Roos A, Smit JWA. Prolonged caloric restriction in obese patients with type 2 diabetes mellitus decreases myocardial triglyceride content and improves myocardial function. J Am Coll Cardiol 2008; 52:1006-12. [PMID: 18786482 DOI: 10.1016/j.jacc.2008.04.068] [Citation(s) in RCA: 182] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2008] [Revised: 04/04/2008] [Accepted: 04/16/2008] [Indexed: 01/09/2023]
Abstract
OBJECTIVES This study sought to assess the effects of prolonged caloric restriction in obese patients with type 2 diabetes mellitus (T2DM) on myocardial triglyceride (TG) content and myocardial function. BACKGROUND Myocardial TG content is increased in patients with T2DM and may reflect altered myocardial function. It is unknown whether myocardial TG content is influenced during a therapeutic intervention. METHODS Myocardial TG content (magnetic resonance [MR] spectroscopy), myocardial function (MR imaging), plasma hemoglobin A1c, and body mass index (BMI) were measured in 12 obese, insulin-treated T2DM patients before and after a 16-week very-low-calorie diet (VLCD) (450 kcal/day) to achieve substantial weight loss. Insulin was stopped during the VLCD. RESULTS The BMI decreased from 35.6 +/- 1.2 kg/m(2) (baseline, mean +/- SEM) to 27.5 +/- 1.3 kg/m(2) (after the VLCD, p < 0.001) and was associated with an improvement in hemoglobin A1c from 7.9 +/- 0.4% (baseline) to 6.3 +/- 0.3% (after the VLCD, p = 0.006). Myocardial TG content decreased from 0.88 +/- 0.12% to 0.64 +/- 0.14%, respectively (p = 0.019), and was associated with improved diastolic function (reflected by the ratio between the early and atrial filling phase) from 1.02 +/- 0.08 to 1.18 +/- 0.06, respectively (p = 0.019). CONCLUSIONS Prolonged caloric restriction in obese T2DM patients decreases BMI and improves glucoregulation associated with decreased myocardial TG content and improved diastolic heart function. Therefore, myocardial TG stores in obese patients with T2DM are flexible and amendable to therapeutic intervention by caloric restriction.
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Affiliation(s)
- Sebastiaan Hammer
- Department of Endocrinology and Metabolism, Leiden University Medical Center, Leiden, the Netherlands.
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258
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Abstract
PURPOSE OF REVIEW Nephrolithiasis is a prominent public health issue. It imposes a substantial burden on human health and is a considerable financial expenditure for the nation. Numerous epidemiologic studies have shown a significant association between nephrolithiasis, obesity, hypertension and chronic kidney disease. The review highlights many of those emerging studies and sheds light on the importance of our recognition of kidney stones as a systemic illness. RECENT FINDINGS Several cross-sectional retrospective studies have investigated the relationship between kidney stones and the metabolic syndrome. The various silent features of the metabolic syndrome, including type 2 diabetes, increased BMI, hypertension and dyslipidemia, are becoming progressively more recognized and independently associated with an increased risk of kidney stone formation. SUMMARY Our further understanding of the underlying mechanisms in the connection between nephrolithiasis and the metabolic syndrome will stimulate the development of more effective preventive and therapeutic measures.
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259
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Lamb HJ, Smit JW, van der Meer RW, Hammer S, Doornbos J, de Roos A, Romijn JA. Metabolic MRI of myocardial and hepatic triglyceride content in response to nutritional interventions. Curr Opin Clin Nutr Metab Care 2008; 11:573-9. [PMID: 18685452 DOI: 10.1097/mco.0b013e32830a98e3] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE OF REVIEW To discuss the technique and clinical applications of myocardial and hepatic H magnetic resonance spectroscopy to study myocardial and hepatic triglyceride content, in relation to changes in plasma nonesterified fatty acids induced by nutritional interventions. RECENT FINDINGS Progressive caloric restriction induces a dose-dependent increase in myocardial triglyceride content and a dose-dependent decrease in diastolic function in lean healthy men. Hepatic triglyceride content shows a differential response to progressive caloric restriction, indicating that redistribution of endogenous triglyceride stores is tissue specific, at least in lean healthy men. A short-term high-fat high-energy diet in healthy men results in major increases in hepatic fat content, whereas it does not influence myocardial triglyceride content or myocardial function. Apparently, there is a differential, tissue-specific partitioning of either triglyceride or fatty acids or both between nonadipose organs such as the human heart and liver during different physiological conditions. SUMMARY Metabolic MRI of myocardial and hepatic triglyceride content is a promising new tool to study the effects of nutritional interventions on myocardial and hepatic lipid metabolism in relation to heart function. Future studies should aim to apply these magnetic resonance techniques to obesity and type 2 diabetes mellitus.
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Affiliation(s)
- Hildo J Lamb
- Department of Radiology, The Netherlands bDepartment of Endocrinology, Leiden University Medical Center, Leiden, The Netherlands.
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260
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Hammer S, van der Meer RW, Lamb HJ, de Boer HH, Bax JJ, de Roos A, Romijn JA, Smit JWA. Short-term flexibility of myocardial triglycerides and diastolic function in patients with type 2 diabetes mellitus. Am J Physiol Endocrinol Metab 2008; 295:E714-8. [PMID: 18628354 DOI: 10.1152/ajpendo.90413.2008] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Short-term caloric restriction increases plasma levels of nonesterified fatty acids (NEFAs) and is associated with increased myocardial triglyceride (TG) content and decreased myocardial function in healthy subjects. Whether this flexibility of myocardial TG stores and myocardial function is also present in patients with type 2 diabetes mellitus (T2DM) is yet unknown. Myocardial TG content and left ventricular (LV) ratio between the early (E) and atrial (A) diastolic filling phase (E/A) were determined using magnetic resonance (MR) spectroscopy and MR imaging, respectively, before and after a 3-day very low-calorie diet (VLCD) in 11 patients with T2DM. In addition, we studied patients after a 3-day VLCD combined with the antilipolytic drug acipimox. The VLCD induced myocardial TG accumulation [from 0.66 +/- 0.09% (mean +/- SE, baseline) to 0.98 +/- 0.16%, P = 0.028] and a decrease in E/A ratio [from 1.00 +/- 0.05 (baseline) to 0.90 +/- 0.06, P = 0.002]. This was associated with increased plasma NEFA levels (from 0.57 +/- 0.08 mmol/l at baseline to 0.92 +/- 0.12, P = 0.019). After the VLCD with acipimox, myocardial TG content, diastolic function, and plasma NEFA levels were similar to baseline values. In conclusion, in patients with T2DM, a VLCD increases myocardial TG content and is associated with a decrease in LV diastolic function. These effects were not observed when a VLCD was combined with acipimox, illustrating the physiological flexibility of myocardial TG stores and myocardial function in patients with T2DM.
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Affiliation(s)
- Sebastiaan Hammer
- Depts. of Endocrinology & Metabolism and Radiology ,Leiden University Medical Center, 2300 RC Leiden, the Netherlands.
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261
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Abstract
The metabolic syndrome describes a cluster of metabolic features that increases the risk for type 2 diabetes mellitus and cardiovascular disease. The prevalence of uric acid nephrolithiasis is higher among stone-forming patients with features of the metabolic syndrome such as obesity and/or type 2 diabetes mellitus. The major determinant in the development of idiopathic uric acid stones is an abnormally low urinary pH. The unduly urinary acidity in uric acid stone formers increasingly is recognized to be one of the features observed in the metabolic syndrome. Two major abnormalities have been implicated to explain this overly acidic urine: (1) increased net acid excretion, and (2) impaired buffering caused by defective urinary ammonium excretion, with the combination resulting in abnormally acidic urine. New information is emerging linking these defects to changes in insulin signaling in the kidney. This article reviews the epidemiologic and metabolic studies linking uric acid nephrolithiasis with the metabolic syndrome, and examines the potential mechanisms underlying the unduly acidic urine in these conditions.
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Affiliation(s)
- Khashayar Sakhaee
- Charles & Jane Pak Center for Mineral Metabolism and Clinical Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390-8885, USA.
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van der Meer RW, Hammer S, Lamb HJ, Frölich M, Diamant M, Rijzewijk LJ, de Roos A, Romijn JA, Smit JWA. Effects of short-term high-fat, high-energy diet on hepatic and myocardial triglyceride content in healthy men. J Clin Endocrinol Metab 2008; 93:2702-8. [PMID: 18430773 DOI: 10.1210/jc.2007-2524] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT An association has been suggested between elevated plasma nonesterified fatty acid (NEFA) levels, myocardial triglyceride (TG) accumulation, and myocardial function. OBJECTIVE Our objective was to investigate the effects of an elevation of plasma NEFA by a high-fat, high-energy (HFHE) diet on hepatic and myocardial TG accumulation, and on myocardial function. DESIGN There were 15 healthy males (mean +/- sd age: 25.0 +/- 6.6 yr) subjected to a 3-d HFHE diet consisting of their regular diet, supplemented with 800 ml cream (280 g fat) every day. METHODS (1)H-magnetic resonance spectroscopy was performed for assessing hepatic and myocardial TGs. Furthermore, left ventricular function was assessed using magnetic resonance imaging. RESULTS The HFHE diet increased hepatic TGs compared with baseline (from 2.01 +/- 1.79 to 4.26 +/- 2.78%; P = 0.001) in parallel to plasma TGs and NEFA. Myocardial TGs did not change (0.38 +/- 0.18 vs. 0.40 +/- 0.12%; P = 0.7). The HFHE diet did not change myocardial systolic function. Diastolic function, assessed by dividing the maximum flow across the mitral valve of the early diastolic filling phase by the maximum flow of the atrial contraction (E/A ratio), decreased compared with baseline (from 2.11 +/- 0.39 to 1.89 +/- 0.33; P = 0.031). This difference was no longer significant after adjustment for heart rate (P = 0.12). CONCLUSIONS Short-term HFHE diet in healthy males results in major increases in plasma TG and NEFA concentrations and hepatic TGs, whereas it does not influence myocardial TGs or myocardial function. These observations indicate differential, tissue-specific partitioning of TGs and/or fatty acids among nonadipose organs during HFHE diet.
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263
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Abstract
The dramatic increase in the prevalence of obesity and its strong association with cardiovascular disease have resulted in unprecedented interest in understanding the effects of obesity on the cardiovascular system. A consistent, but puzzling clinical observation is that obesity confers an increased susceptibility to the development of cardiac disease, while at the same time affording protection against subsequent mortality (termed the obesity paradox). In this review we focus on evidence available from human and animal model studies and summarize the ways in which obesity can influence structure and function of the heart. We also review current hypotheses regarding mechanisms linking obesity and various aspects of cardiac remodeling. There is currently great interest in the role of adipokines, factors secreted from adipose tissue, and their role in the numerous cardiovascular complications of obesity. Here we focus on the role of leptin and the emerging promise of adiponectin as a cardioprotective agent. The challenge of understanding the association between obesity and heart failure is complicated by the multifaceted interplay between various hemodynamic, metabolic, and other physiological factors that ultimately impact the myocardium. Furthermore, the end result of obesity-associated changes in the myocardial structure and function may vary at distinct stages in the progression of remodeling, may depend on the individual pathophysiology of heart failure, and may even remain undetected for decades before clinical manifestation. Here we summarize our current knowledge of this complex yet intriguing topic.
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Affiliation(s)
- E Dale Abel
- Department of Biology, York University, Toronto, Canada
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264
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Abstract
Ectopic fat is defined by the deposition of triglycerides within cells of non-adipose tissue that normally contain only small amounts of fat. Over the past decade, magnetic resonance spectroscopy has been used extensively for noninvasive quantification of intramyocellular, intrahepatocellular, and more recently myocardial and pancreatic lipids. In liver and muscle, triglyceride content usually correlates with whole-body and tissue-specific insulin sensitivity. However, fat mass and oxidative capacity influence this relationship, indicating that ectopic lipid content is not the only factor that explains insulin resistance. Ectopic lipids may rather serve as biomarkers of the balance between metabolic supply and demand in different states of insulin sensitivity. Consequently, ectopic lipid concentrations, particularly in the liver, decrease with lifestyle- or drug-induced improvement of insulin sensitivity.
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Affiliation(s)
- Angelika Lettner
- Medical Department, Hanusch Hospital, Karl-Landsteiner Institute of Endocrinology and Metabolism, Heinrich Collin Strasse 30, A-1140 Vienna, Austria
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265
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van der Meer RW, Rijzewijk LJ, Diamant M, Hammer S, Schär M, Bax JJ, Smit JWA, Romijn JA, de Roos A, Lamb HJ. The ageing male heart: myocardial triglyceride content as independent predictor of diastolic function. Eur Heart J 2008; 29:1516-22. [PMID: 18492680 DOI: 10.1093/eurheartj/ehn207] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
AIMS In animal models of obesity and diabetes mellitus, myocardial TG accumulation is associated with decreased myocardial function. In the physiologically ageing heart, myocardial triglyceride (TG) accumulation may also occur due to reduced myocardial fatty acid oxidation. The role of myocardial TG in the ageing human heart is unknown. Therefore, the purpose of our study was to evaluate the effects of ageing on myocardial TG content, and to determine the association between myocardial TG content and heart function. METHODS AND RESULTS 1H-magnetic resonance spectroscopy and magnetic resonance imaging of the heart were performed in 43 healthy male subjects. Mean age (range) of the subjects was 44 (20-66) years. Body mass index (BMI), blood pressure, and biochemical markers were determined. Age correlated significantly to myocardial TG content (r = 0.57, P < 0.05) independently of BMI. Furthermore, myocardial TG content correlated negatively with left ventricular diastolic function (represented by E/A ratio, r = -0.68, P < 0.05). Multivariable analysis indicated myocardial TG content as independent predictor (P < 0.05) of the age related decrease in diastolic heart function. CONCLUSION Myocardial TG content increases in the physiologically ageing male heart and is associated with the age-related decline in diastolic function, independent of BMI, blood pressure, and biochemical blood markers.
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Affiliation(s)
- Rutger W van der Meer
- Department of Radiology (C2-S), Leiden University Medical Center, PO Box 9600, 2300 RC Leiden, The Netherlands.
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266
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Adipogenic capacity and the susceptibility to type 2 diabetes and metabolic syndrome. Proc Natl Acad Sci U S A 2008; 105:6139-44. [PMID: 18413598 DOI: 10.1073/pnas.0801981105] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
To determine whether adipocyte storage capacity influences the onset and severity of type 2 diabetes and other components of the metabolic syndrome, we made normal and db/db mice resistant to obesity by overexpressing leptin receptor-b on the aP2-Lepr-b promoter. On a 4% diet, these mice have no phenotype, but on a 60% fat diet, they resist diet-induced obesity because constitutive adipocyte-specific overexpression of Lepr-b prevents obesity via the antilipogenic autocrine/paracrine action of leptin on adipocytes. After 8 months on the same 60% fat diet, body fat of transgenic mice was 70% below WT controls. Cardiac and liver fat was elevated in the transgenics, and their hyperinsulinemia was more marked, suggesting greater insulin resistance. The aP2-Lepr-b transgene also prevented obesity in db/db mice; at 10 weeks of age their body fat was half that of the db/db mice. This lack of obesity was attributable to reduced expression of sterol regulatory element binding protein-1c and its target lipogenic enzymes in adipose tissue and a 6-fold increase in Pref-1 mRNA. Severe diabetes was present in transgenics at 4 weeks of age, 10 weeks before db/db controls. Echocardiographic evidence of cardiomyopathy appeared at 10 weeks, weeks before the db/db mice. Histologically, loss of beta cells and myocardial fibrosis was present in the transgenic group at least 6 weeks before the db/db mice. These results suggest that the expression level of genes that regulate the adipogenic response to overnutrition profoundly influences the age of onset and severity of diet-induced type 2 diabetes and co-morbidities.
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267
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Abstract
Insulin resistance is characteristic of obesity, type 2 diabetes, and components of the cardiometabolic syndrome, including hypertension and dyslipidemia, that collectively contribute to a substantial risk for cardiovascular disease. Metabolic actions of insulin in classic insulin target tissues (eg, skeletal muscle, fat, and liver), as well as actions in nonclassic targets (eg, cardiovascular tissue), help to explain why insulin resistance and metabolic dysregulation are central in the pathogenesis of the cardiometabolic syndrome and cardiovascular disease. Glucose and lipid metabolism are largely dependent on mitochondria to generate energy in cells. Thereby, when nutrient oxidation is inefficient, the ratio of ATP production/oxygen consumption is low, leading to an increased production of superoxide anions. Reactive oxygen species formation may have maladaptive consequences that increase the rate of mutagenesis and stimulate proinflammatory processes. In addition to reactive oxygen species formation, genetic factors, aging, and reduced mitochondrial biogenesis all contribute to mitochondrial dysfunction. These factors also contribute to insulin resistance in classic and nonclassic insulin target tissues. Insulin resistance emanating from mitochondrial dysfunction may contribute to metabolic and cardiovascular abnormalities and subsequent increases in cardiovascular disease. Furthermore, interventions that improve mitochondrial function also improve insulin resistance. Collectively, these observations suggest that mitochondrial dysfunction may be a central cause of insulin resistance and associated complications. In this review, we discuss mechanisms of mitochondrial dysfunction related to the pathophysiology of insulin resistance in classic insulin-responsive tissue, as well as cardiovascular tissue.
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Affiliation(s)
- Jeong-A Kim
- Department of Internal Medicine, University of Missouri-Columbia School of Medicine, Columbia, Missouri, USA
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268
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269
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Abstract
Thiazolidinediones (TZDs) are relatively new agents for the treatment of type 2 diabetes. They act as agonists at the PPAR-gamma nuclear receptor and their therapeutic effects include decreased insulin resistance and hyperglycaemia, an improved plasma lipid, inflammation and pro-coagulant profile, and amelioration of hypertension, microalbuminuria and hepatic steatosis. The most common side effects of TZDs include weight gain and oedema, with occasional reports of congestive heart failure (CHF). This review discusses the benefit-risk profile of TZDs in treating patients with type 2 diabetes, with particular reference to the heart. To provide context, we explore briefly the epidemiology and pathophysiology of heart failure in patients with type 2 diabetes, touch on the association of heart disease and cardiovascular mortality with antihyperglycaemic treatment modalities other than TZDs, and then focus on the effects of TZDs on the heart, cardiovascular risk factors and outcomes. We describe the cluster of host factors, which seems to predispose patients with type 2 diabetes to TZD-induced or TZD-exacerbated oedema and CHF and then provide an overview of the putative mechanisms of these TZD-related side effects. We also propose that certain diuretics (amiloride and spironolactone), by targeting the distal nephron that expresses PPARgamma in collecting duct cells, might be of benefit in ameliorating the fluid retention and oedema associated with TZDs.
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Affiliation(s)
- R E Buckingham
- Unit for Metabolic Medicine, Department of Diabetes & Endocrinology, Cardiovascular Division, King's College London School of Medicine, Guy's Hospital, King's College London, London UK.
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270
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Chess DJ, Stanley WC. Role of diet and fuel overabundance in the development and progression of heart failure. Cardiovasc Res 2008; 79:269-78. [PMID: 18343896 DOI: 10.1093/cvr/cvn074] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Under physiological conditions, the human heart derives energy from glucose, fatty acids, and/or lactate depending upon substrate availability, circulating hormone levels, and nutritional status. Circulating free fatty acid and glucose levels often exceed the normal range, as observed with type 2 diabetes, obesity, or physical inactivity. Chronic exposure of the heart to high plasma levels of free fatty acids may cause accumulation of toxic lipid intermediates within cardiomyocytes. Furthermore, suppression of glucose oxidation by increased fatty acid uptake shunts glucose into the oxidative pentose phosphate and hexosamine biosynthetic pathways, both of which yield potentially harmful products. Noxious derivatives of aberrant glucose and fatty acid oxidation can activate signalling cascades leading to myocyte dysfunction or death, processes termed 'glucotoxicity' and 'lipotoxicity'. This review discusses the effects of dietary extremes (e.g. high fat and high carbohydrate consumption) and substrate overabundance in the context of heart failure (HF) development and progression. Emerging data suggest that substrate excess leads to cardiac dysfunction and HF, which may be prevented or slowed by maintaining low body fat and high insulin sensitivity and consuming a diet of low glycaemic load that is high in mono- and polyunsaturated fatty acids.
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Affiliation(s)
- David J Chess
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
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271
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Gustafson D. A life course of adiposity and dementia. Eur J Pharmacol 2008; 585:163-75. [PMID: 18423446 DOI: 10.1016/j.ejphar.2008.01.052] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2007] [Revised: 12/11/2007] [Accepted: 01/21/2008] [Indexed: 01/12/2023]
Abstract
Adiposity, commonly measured as body mass index (BMI), may influence or be influenced by brain structures and functions involved in dementia processes. Adipose tissue changes in degree and intensity over the lifespan, and has been shown to influence brain development in relationship to early and late measures of cognitive function, intelligence, and disorders of cognition such as dementia. A lower BMI is associated with prevalent dementia, potentially due to underlying brain pathologies and correspondingly greater rates of BMI or weight decline observed during the years immediately preceding clinical dementia onset. However, high BMI during mid-life or at least approximately 5-10 years preceding clinical dementia onset may increase risk. The interplay of adiposity and the brain occurring over the course of the lifespan will be discussed in relationship to developmental origins, mid-life sequelae, disruptions in brain structure and function, and late-life changes in cognition and dementia. Characterizing the life course of adiposity among those who do and do not become demented enhances understanding of biological underpinnings relevant for understanding the etiologies of both dementia and obesity and their co-existence.
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Affiliation(s)
- Deborah Gustafson
- Institute of Neuroscience and Physiology, Section for Psychiatry and Neurochemistry, Sahlgrenska Academy at Göteborg University, Sweden.
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272
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Karuparthi PR, Yerram P, Govindarajan G, Hayden MR. Obesity and cardiovascular risk. CURRENT CARDIOVASCULAR RISK REPORTS 2008. [DOI: 10.1007/s12170-008-0022-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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273
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Molecular mechanisms for myocardial mitochondrial dysfunction in the metabolic syndrome. Clin Sci (Lond) 2008; 114:195-210. [PMID: 18184113 DOI: 10.1042/cs20070166] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The metabolic syndrome represents a cluster of abnormalities, including obesity, insulin resistance, dyslipidaemia and Type 2 diabetes, that increases the risk of developing cardiovascular diseases, such as coronary artery disease and heart failure. The heart failure risk is increased even after adjusting for coronary artery disease and hypertension, and evidence is emerging that changes in cardiac energy metabolism might contribute to the development of contractile dysfunction. Recent findings suggest that myocardial mitochondrial dysfunction may play an important role in the pathogenesis of cardiac contractile dysfunction in obesity, insulin resistance and Type 2 diabetes. This review will discuss potential molecular mechanisms for these mitochondrial abnormalities.
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274
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Feuvray D, Darmellah A. Diabetes-related metabolic perturbations in cardiac myocyte. DIABETES & METABOLISM 2008; 34 Suppl 1:S3-9. [DOI: 10.1016/s1262-3636(08)70096-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2007] [Accepted: 10/30/2007] [Indexed: 12/21/2022]
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275
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Hammer S, van der Meer RW, Lamb HJ, Schär M, de Roos A, Smit JWA, Romijn JA. Progressive caloric restriction induces dose-dependent changes in myocardial triglyceride content and diastolic function in healthy men. J Clin Endocrinol Metab 2008; 93:497-503. [PMID: 18029455 DOI: 10.1210/jc.2007-2015] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
CONTEXT In animal experiments, high plasma concentrations of free fatty acids (FFAs) are associated with increased triglyceride (TG) stores in liver and heart, and impaired cardiac function. In humans caloric restriction increases plasma FFA levels. OBJECTIVE Our objective was to assess the effects of progressive caloric restriction on myocardial and hepatic TG content and myocardial function. DESIGN This was a prospective intervention study. PARTICIPANTS This study included 10 lean healthy men. INTERVENTIONS Three-day partial (471 kcal/d) and complete starvation was performed. OUTCOME MEASURES Plasma levels of FFA, myocardial and hepatic TG content, and myocardial function were calculated. RESULTS Plasma FFA increased from 0.6 +/- 0.4 mmol/liter to 1.2 +/- 0.4 and to 1.9 +/- 0.7 mmol/liter, after partial and complete starvation, respectively (P < 0.001). Myocardial TG content increased from 0.35 +/- 0.14% to 0.59 +/- 0.27%, and 1.26 +/- 0.49%, respectively (P < 0.01). The ratio between the early diastole and atrial contraction decreased from 2.2 +/- 0.4 to 2.1 +/- 0.4 (P = 0.7) and 1.8 +/- 0.4, respectively (P < 0.01), and diastolic early deceleration from 3.4 +/- 0.7 ml/sec(2) x 10(-3) to 2.9 +/- 0.5 and 2.8 +/- 0.9 ml/sec(2) x 10(-3), respectively (P < 0.05). Hepatic TG content decreased after partial starvation (from 2.23 +/- 2.24% to 1.43 +/- 1.33%; P < 0.05) but did not change upon complete starvation. CONCLUSIONS Progressive caloric restriction induces a dose-dependent increase in myocardial TG content and a dose-dependent decrease in diastolic function in lean healthy men. Hepatic TG content showed a differential response to progressive caloric restriction, indicating that redistribution of endogenous TG stores is tissue specific.
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Affiliation(s)
- Sebastiaan Hammer
- Department of Endocrinology and Metabolism (C4-R), Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, The Netherlands.
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276
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Mittendorfer B, Peterson LR. Cardiovascular Consequences of Obesity and Targets for Treatment. DRUG DISCOVERY TODAY. THERAPEUTIC STRATEGIES 2008; 5:53-61. [PMID: 19343099 PMCID: PMC2630250 DOI: 10.1016/j.ddstr.2008.07.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Obesity is a risk factor for cardiovascular disease, including coronary artery disease and heart failure, but the mechanisms by which it may cause them are not completely clear. Currently, therapies aimed at obesity-related cardiovascular disease include weight loss strategies and reduction of the other risk factors that are associated with obesity and cardiovascular disease. Other pathways with for potential drug development for obesity-related CVD are also discussed.
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Affiliation(s)
- Bettina Mittendorfer
- Department of Medicine, divisions of geriatrics and nutritional sciences, Washington University School of Medicine, St. Louis, MO, USA
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277
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Peterson LR, Herrero P, McGill J, Schechtman KB, Kisrieva-Ware Z, Lesniak D, Gropler RJ. Fatty acids and insulin modulate myocardial substrate metabolism in humans with type 1 diabetes. Diabetes 2008; 57:32-40. [PMID: 17914030 DOI: 10.2337/db07-1199] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Normal human myocardium switches substrate metabolism preference, adapting to the prevailing plasma substrate levels and hormonal milieu, but in type 1 diabetes, the myocardium relies heavily on fatty acid metabolism for energy. Whether conditions that affect myocardial glucose use and fatty acid utilization, oxidation, and storage in nondiabetic subjects alter them in type 1 diabetes is not well known. RESEARCH DESIGN AND METHODS To test the hypotheses that in humans with type 1 diabetes, myocardial glucose and fatty acid metabolism can be manipulated by altering plasma free fatty acid (FFA) and insulin levels, we quantified myocardial oxygen consumption (MVo(2)), glucose, and fatty acid metabolism in nondiabetic subjects and three groups of type 1 diabetic subjects (those studied during euglycemia, hyperlipidemia, and a hyperinsulinemic-euglycemic clamp) using positron emission tomography. RESULTS Type 1 diabetic subjects had higher MVo(2) and lower myocardial glucose utilization rate/insulin than control subjects. In type 1 diabetes, glucose utilization increased with increasing plasma insulin and decreasing FFA levels. Myocardial fatty acid utilization, oxidation, and esterification rates increased with increasing plasma FFA. Increasing plasma insulin levels decreased myocardial fatty acid esterification rates but increased the percentage of fatty acids going into esterification. CONCLUSIONS Type 1 diabetes myocardium has increased MVo(2) and is insulin resistant during euglycemia. However, its myocardial glucose and fatty acid metabolism still responds to changes in plasma insulin and plasma FFA levels. Moreover, insulin and plasma FFA levels can regulate the intramyocardial fate of fatty acids in humans with type 1 diabetes.
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Affiliation(s)
- Linda R Peterson
- Cardiovascular Division, Department of Internal Medicine, Mallinckrodt Institute, Washington University School of Medicine, St. Louis, Missouri, USA.
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278
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van Herpen NA, Schrauwen-Hinderling VB. Lipid accumulation in non-adipose tissue and lipotoxicity. Physiol Behav 2007; 94:231-41. [PMID: 18222498 DOI: 10.1016/j.physbeh.2007.11.049] [Citation(s) in RCA: 354] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2007] [Revised: 11/21/2007] [Accepted: 11/22/2007] [Indexed: 12/17/2022]
Abstract
Obesity is a well-known risk factor for the development of type 2 diabetes mellitus and cardiovascular disease. Importantly, obesity is not only associated with lipid accumulation in adipose tissue, but also in non-adipose tissues. The latter is also known as ectopic lipid accumulation and may be a possible link between obesity and its comorbidities such as insulin resistance, type 2 diabetes mellitus and cardiovascular disease. In skeletal muscle and liver, lipid accumulation has been associated with the development of insulin resistance, an early hallmark of developing type 2 diabetes mellitus. More specifically, accumulation of intermediates of lipid metabolism, such as diacylglycerol (DAG) and Acyl-CoA have been shown to interfere with insulin signaling in these tissues. Initially, muscular and hepatic insulin resistance can be overcome by an increased insulin production by the pancreas, resulting in hyperinsulinemia. However, during the progression towards overt type 2 diabetes, pancreatic failure occurs resulting in reduced insulin production. Interestingly, also in the pancreas lipid accumulation has been shown to precede dysfunction. Finally, accumulation of fat in the heart has been associated with cardiac dysfunction and heart failure, which may be an explanation for diabetic cardiomyopathy. Taken together, we conclude that evidence for deleterious effects of lipid accumulation in non-adipose tissue (lipotoxicity) is strong. However, while ample human data is available for skeletal muscle and the liver, future research should focus on lipid accumulation in the pancreas and the heart.
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Affiliation(s)
- N A van Herpen
- Top Institute Food and Nutrition, 6700 AN Wageningen, The Netherlands.
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279
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van der Meer RW, Hammer S, Smit JWA, Frölich M, Bax JJ, Diamant M, Rijzewijk LJ, de Roos A, Romijn JA, Lamb HJ. Short-term caloric restriction induces accumulation of myocardial triglycerides and decreases left ventricular diastolic function in healthy subjects. Diabetes 2007; 56:2849-53. [PMID: 17717279 DOI: 10.2337/db07-0768] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
OBJECTIVE Diabetes and obesity are associated with increased plasma nonesterified fatty acid (NEFA) levels, myocardial triglyceride accumulation, and myocardial dysfunction. Because a very low-calorie diet (VLCD) also increases plasma NEFA levels, we studied the effect of a VLCD on myocardial triglyceride content and cardiac function in healthy subjects. RESEARCH DESIGN AND METHODS Fourteen healthy nonobese men underwent (1)H-magnetic resonance spectroscopy (MRS) to determine myocardial and hepatic triglyceride content, (31)P-MRS to assess myocardial high-energy phosphate (HEP) metabolism (phosphocreatine/ATP), and magnetic resonance imaging of myocardial function at baseline and after a 3-day VLCD. RESULTS After the dietary intervention, plasma NEFA levels increased compared with those at baseline (from 0.5 +/- 0.1 to 1.1 +/- 0.1 mmol/l, P < 0.05). Concomitantly, myocardial triglyceride content increased by approximately 55% compared with that at baseline (from 0.38 +/- 0.05 to 0.59 +/- 0.06%, P < 0.05), whereas liver triglyceride content decreased by approximately 32% (from 2.2 +/- 0.5 to 1.5 +/- 0.4%, P < 0.05). The VLCD did not change myocardial phosphocreatine-to-ATP ratio (2.33 +/- 0.15 vs. 2.33 +/- 0.08, P > 0.05) or systolic function. Interestingly, deceleration of the early diastolic flow across the mitral valve decreased after the VLCD (from 3.37 +/- 0.20 to 2.91 +/- 0.16 ml/s(2) x 10(-3), P < 0.05). This decrease in diastolic function was significantly correlated with the increase in myocardial triglyceride content. CONCLUSIONS Short-term VLCD induces accumulation of myocardial triglycerides. In addition, VLCD decreases left ventricular diastolic function, without alterations in myocardial HEP metabolism. This study documents diet-dependent physiological variations in myocardial triglyceride content and diastolic function in healthy subjects.
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Affiliation(s)
- Rutger W van der Meer
- Department of Radiology, C2S, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, Netherlands.
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280
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Szczepaniak LS, Victor RG, Orci L, Unger RH. Forgotten but not gone: the rediscovery of fatty heart, the most common unrecognized disease in America. Circ Res 2007; 101:759-67. [PMID: 17932333 DOI: 10.1161/circresaha.107.160457] [Citation(s) in RCA: 188] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Until 60 years ago, fatty heart was an accepted clinical entity. Since then, its very existence has been questioned, despite the fact that 2 of 3 Americans are now obese or overweight and obesity has been shown to be correlated with cardiac functional abnormalities. In 2000, a syndrome of "lipotoxic cardiomyopathy" resembling earlier pathologic descriptions of fatty human hearts was described in rodents, and fatty infiltration of cardiomyocytes was subsequently reported in patients with congestive failure. Now, magnetic resonance spectroscopy has been adapted to permit routine noninvasive screening for fatty heart. The use of this technique in human volunteers indicates that cardiomyocyte fat correlates well with body mass index and is elevated in uncomplicated obesity. It is more severe when glucose tolerance becomes abnormal or diabetes is present. It is associated with impaired diastolic filling, even in seemingly asymptomatic obese volunteers. Because fatty heart can be readily prevented by lifestyle modification and pharmacologic interventions that reduce caloric intake and increase fatty acid oxidation, it seems important to recognize its existence so as to intervene as early as possible.
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Affiliation(s)
- Lidia S Szczepaniak
- Department of Internal Medicine, Division of Hypertension, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Blvd, Dallas, TX 75390, USA
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281
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van der Meer RW, Doornbos J, Kozerke S, Schär M, Bax JJ, Hammer S, Smit JWA, Romijn JA, Diamant M, Rijzewijk LJ, de Roos A, Lamb HJ. Metabolic Imaging of Myocardial Triglyceride Content: Reproducibility of1H MR Spectroscopy with Respiratory Navigator Gating in Volunteers. Radiology 2007; 245:251-7. [PMID: 17885193 DOI: 10.1148/radiol.2451061904] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Institutional review board approval and informed consent were obtained. The purpose of the study was to prospectively compare spectral resolution and reproducibility of hydrogen 1 (1H) magnetic resonance (MR) spectroscopy, with and without respiratory motion compensation based on navigator echoes, in the assessment of myocardial triglyceride content in the human heart. In 20 volunteers (14 men, six women; mean age+/-standard error, 31 years+/-2.8 [range, 19-60 years]; body mass index, 19-30 kg/m2) without history of cardiovascular disease, 1H MR spectroscopy of the myocardium was performed at rest, with and without respiratory motion compensation. Unsuppressed water signal linewidth changed from 11.9 Hz to 10.7 Hz (P<.001) with the use of the navigator, which indicated better spectral resolution. The navigator improved the intraclass correlation coefficient for the assessment of myocardial triglyceride content from 0.32 to 0.81. Therefore, the authors believe that respiratory motion correction is essential for reproducible assessment of myocardial triglycerides.
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Affiliation(s)
- Rutger W van der Meer
- Department of Radiology, Leiden University Medical Center, Albinusdreef 2, C2-S, 2333 ZA Leiden, the Netherlands
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282
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Abstract
Introduction Cardiovascular molecular imaging is a rapidly evolving field of research, aiming to image and quantify molecular and cellular targets in vivo. MR imaging has some inherent properties that make it very suitable for cardiovascular molecular imaging. Until now, only a limited number of studies have been published on cardiovascular molecular imaging using MR imaging. Review In the current review, MR techniques that have already shown potential are discussed. Metabolic MR imaging can be performed by 31P-MR spectroscopy, 23Na MR spectroscopy and 1H-MR spectroscopy; some examples are shown. Furthermore, a concise overview is given of several aspecific and specific contrast agents for cardiovascular molecular MR imaging, such as gadolinium-based contrast agents, iron oxide MR contrast agents and fibrin-targeted MR contrast agents. Conclusion We expect that in the next decade currently promising MR molecular imaging agents will be introduced into the clinical arena to guide diagnosis and therapy of cardiovascular disease.
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Affiliation(s)
- H J Lamb
- Department of Radiology, C2S, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, The Netherlands.
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283
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Di Bello V, Santini F, Di Cori A, Pucci A, Talini E, Palagi C, Delle Donne MG, Marsili A, Fierabracci P, Valeriano R, Scartabelli G, Giannetti M, Anselmino M, Pinchera A, Mariani M. Effects of Bariatric Surgery on Early Myocardial Alterations in Adult Severely Obese Subjects. Cardiology 2007; 109:241-8. [PMID: 17873488 DOI: 10.1159/000107787] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2006] [Accepted: 01/12/2007] [Indexed: 11/19/2022]
Abstract
OBJECTIVE Aim of this study was to investigate the effect of weight loss on structural and functional myocardial alterations in severely obese subjects treated with bariatric surgery. PATIENTS AND METHODS Thirteen severely obese patients (2 males and 11 females) were enrolled in the study. All subjects underwent conventional 2D color Doppler echocardiography. The new ultrasonic techniques used were: (a) integrated backscatter for the analysis of myocardial reflectivity, referred to pericardial interface as expression of myocardial structure (increase in collagen content) and of cyclic variation index as expression of intrinsic myocardial contractility and (b) color Doppler myocardial imaging (CDMI) for the analysis of strain and strain rate (myocardial deformability). All subjects underwent bariatric surgery and were resubmitted to echocardiographic and biochemical examination 6-24 months after surgery. RESULTS The main finding of the present study was a quite complete normalization of myocardial functional and structural alterations after weight loss. In particular, the cyclic variation index at septum level improved from 14.6 +/- 7.0 before to 25.7 +/- 11.2 (means +/- SD) after surgery (controls: 36.2 +/- 9.1). Mean reflectivity at septum level significantly decreased from 55.8 +/- 9.5 to 46.5 +/- 8.8 (controls: 43.0 +/- 8.0). Also, the strain at septum level significantly improved after surgery (from -11.9 +/- 3.2 to -20.4 +/- 5.3; controls: -23.4 +/- 9). CONCLUSION This study establishes: (a) the utility of new ultrasonic techniques to detect very early structural and functional myocardial alterations in severely obese patients, and (b) the regression of these subclinical abnormalities after weight loss achieved by bariatric surgery.
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284
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Abstract
Obesity results in marked alterations in cardiac energy metabolism, with a prominent effect being an increase in fatty acid uptake and oxidation by the heart. Obesity also results in dramatic changes in the release of adipokines, such as leptin and adiponectin, both of which have emerged as important regulators of cardiac energy metabolism. The link among obesity, cardiovascular disease, lipid metabolism, and adipokine signaling is complex and not well understood. However, optimizing cardiac energy metabolism in obese subjects may be one approach to preventing and treating cardiac dysfunction that can develop in this population. This review discusses what is presently known about the effects of obesity and the impact adipokines have on cardiac energy metabolism and insulin signaling. The clinical implications of obesity and energy metabolism on cardiac disease are also discussed.
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Affiliation(s)
- Gary D Lopaschuk
- Cardiovascular Research Group, University of Alberta, Edmonton, Alberta, Canada.
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285
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Affiliation(s)
- Frederick L Ruberg
- C-8 Section of Cardiology, Boston Medical Center, 88 E Newton St, Boston, MA 02118, USA.
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286
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O'Connor RD, Gropler RJ, Peterson L, Schaffer J, Ackerman JJH. Limits of a localized magnetic resonance spectroscopy assay for ex vivo myocardial triacylglycerol. J Pharm Biomed Anal 2007; 45:382-9. [PMID: 17931816 DOI: 10.1016/j.jpba.2007.08.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2007] [Revised: 08/27/2007] [Accepted: 08/29/2007] [Indexed: 01/15/2023]
Abstract
Localized magnetic resonance spectroscopy (LMRS) promises a powerful non-invasive means to determine myocardial triacylglycerol (TAG) in a clinical setting. Here, the linearity, specificity, robustness, precision, and accuracy of an ex vivo mouse-heart LMRS TAG assay are assessed by quantifying the spatial, spectral, and relaxation-induced uncertainties. The protocol, which is based on localization by adiabatic selective refocusing (LASER) using frequency offset corrected inversion (FOCI) pulses, alternating gradient polarity, and simple post-processing, is shown to have good characteristics. The presented protocol has a benchmark, phantom-based, accuracy of 3%, and when applied to ex vivo mouse hearts the accuracy is 6%, making the LMRS assay comparable to the typical destructive bioanalytical assay.
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Affiliation(s)
- Robert D O'Connor
- Department of Radiology, Washington University, Saint Louis, MO 63110, USA
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287
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McGavock JM, Lingvay I, Zib I, Tillery T, Salas N, Unger R, Levine BD, Raskin P, Victor RG, Szczepaniak LS. Cardiac steatosis in diabetes mellitus: a 1H-magnetic resonance spectroscopy study. Circulation 2007; 116:1170-5. [PMID: 17698735 DOI: 10.1161/circulationaha.106.645614] [Citation(s) in RCA: 465] [Impact Index Per Article: 27.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
BACKGROUND The risk of heart failure in type 2 diabetes mellitus is greater than can be accounted for by hypertension and coronary artery disease. Rodent studies indicate that in obesity and type 2 diabetes mellitus, lipid overstorage in cardiac myocytes produces lipotoxic intermediates that cause apoptosis, which leads to heart failure. In humans with diabetes mellitus, cardiac steatosis previously has been demonstrated in explanted hearts of patients with end-stage nonischemic cardiomyopathy. Whether cardiac steatosis precedes the onset of cardiomyopathy in individuals with impaired glucose tolerance or in patients with type 2 diabetes mellitus is unknown. METHODS AND RESULTS To represent the progressive stages in the natural history of type 2 diabetes mellitus, we stratified 134 individuals (age 45+/-12 years) into 1 of 4 groups: (1) lean normoglycemic (lean), (2) overweight and obese normoglycemic (obese), (3) impaired glucose tolerance, and (4) type 2 diabetes mellitus. Localized (1)H magnetic resonance spectroscopy and cardiac magnetic resonance imaging were used to quantify myocardial triglyceride content and left ventricular function, respectively. Compared with lean subjects, myocardial triglyceride content was 2.3-fold higher in those with impaired glucose tolerance and 2.1-fold higher in those with type 2 diabetes mellitus (P<0.05). Left ventricular ejection fraction was normal and comparable across all groups. CONCLUSIONS In humans, impaired glucose tolerance is accompanied by cardiac steatosis, which precedes the onset of type 2 diabetes mellitus and left ventricular systolic dysfunction. Thus, lipid overstorage in human cardiac myocytes is an early manifestation in the pathogenesis of type 2 diabetes mellitus and is evident in the absence of heart failure.
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Affiliation(s)
- Jonathan M McGavock
- Department of Internal Medicine, Divisions of Hypertension, University of Texas Southwestern Medical Center at Dallas, Dallas, Tex, USA
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288
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Abstract
Diabetes mellitus increases the risk of heart failure independently of underlying coronary artery disease, and many believe that diabetes leads to cardiomyopathy. The underlying pathogenesis is partially understood. Several factors may contribute to the development of cardiac dysfunction in the absence of coronary artery disease in diabetes mellitus. This review discusses the latest findings in diabetic humans and in animal models and reviews emerging new mechanisms that may be involved in the development and progression of cardiac dysfunction in diabetes.
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Affiliation(s)
- Sihem Boudina
- Division of Endocrinology, Metabolism and Diabetes and Program in Human Molecular Biology and Genetics, University of Utah School of Medicine, Salt Lake City 84112, USA
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289
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Banerjee S, Peterson LR. Myocardial metabolism and cardiac performance in obesity and insulin resistance. Curr Cardiol Rep 2007; 9:143-9. [PMID: 17430682 DOI: 10.1007/bf02938341] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Obesity, insulin resistance, and their frequent complication of type 2 diabetes are risk factors for left ventricular diastolic dysfunction, systolic dysfunction, and clinical heart failure. Although obesity, insulin resistance, and diabetes are risk factors for coronary artery disease, and hence ischemic cardiomyopathy-related heart failure, there is increasing evidence that these three risk factors are implicated in the development of cardiac dysfunction not related to epicardial coronary disease. There are several mechanisms by which this triad may cause cardiac dysfunction, including alterations in myocardial metabolism, which may initially be adaptations but evolve into maladaptive responses over time. Recent advances in our understanding of these mechanisms will aid in the development of novel therapies, including metabolic manipulations that could prevent and treat cardiac dysfunction in patients with obesity, insulin resistance, and diabetes.
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Affiliation(s)
- Stacy Banerjee
- Washington University School of Medicine, Department of Medicine, St. Louis, MO 63110, USA
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290
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Perseghin G, Ntali G, De Cobelli F, Lattuada G, Esposito A, Belloni E, Canu T, Costantino F, Ragogna F, Scifo P, Del Maschio A, Luzi L. Abnormal left ventricular energy metabolism in obese men with preserved systolic and diastolic functions is associated with insulin resistance. Diabetes Care 2007; 30:1520-6. [PMID: 17384336 DOI: 10.2337/dc06-2429] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Perturbations in cardiac energy metabolism might represent early alterations in diabetes preceding functional and pathological changes. We evaluated left ventricular (LV) structure/geometry and function in relation to energy metabolism and cardiovascular risk factors in overweight/obese men using magnetic resonance techniques. RESEARCH DESIGN AND METHODS We studied 81 healthy men (aged 22-55 years, with BMI between 19 and 35 kg/m2) by means of cardiac magnetic resonance imaging and 31P-magnetic resonance spectroscopy in the resting and fasted conditions and stratified them in quartiles of BMI (cut offs: 23.2, 25.5 and 29.0 kg/m2). RESULTS LV mass increased across quartiles of BMI; meanwhile, the volumes did not differ. Parameters of LV systolic and diastolic function were not different among quartiles. The phosphocreatine-to-ATP ratio was reduced across increasing quartiles of mean +/- SD BMI (2.25 +/- 0.52, 1.89 +/- 0.26, 1.99 +/- 0.38, and 1.79 +/- 0.29; P < 0.006) in association with insulin sensitivity (computer homeostasis model assessment 2 model); this relation was independent of age, BMI, blood pressure, wall mass, HDL cholesterol, triglycerides, smoking habits, and metabolic syndrome. CONCLUSIONS Abnormal LV energy metabolism was detectable in obese men in the presence of normal function, supporting the hypothesis that metabolic remodeling in insulin resistant states precedes functional and structural/geometrical remodeling of the heart regardless of the onset of overt hyperglycemia.
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Affiliation(s)
- Gianluca Perseghin
- Section of Nutrition/Metabolism, Department of Internal Medicine, Istituto Scientifico San Raffaele, Milano, Italy.
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291
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Nelson RH, Prasad A, Lerman A, Miles JM. Myocardial uptake of circulating triglycerides in nondiabetic patients with heart disease. Diabetes 2007; 56:527-30. [PMID: 17259402 DOI: 10.2337/db06-1552] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Animal studies indicate that oversupply of fatty acids derived from the action of cardiac lipoprotein lipase (LPL) on plasma lipoproteins may contribute to myocardial dysfunction. However, the contribution of circulating triglycerides to myocardial fatty acid supply in humans is not known. Six postabsorptive nondiabetic subjects who were scheduled for diagnostic coronary angiography were studied. (14)C oleate and a lipid emulsion labeled with (3)H triolein were infused to assess myocardial uptake of free fatty acids (FFAs) and triglycerides, as well as myocardial spillover of LPL-generated fatty acids. Six paired blood samples were taken from the femoral artery and the coronary sinus. Coronary sinus concentrations of unlabeled triglycerides were slightly, but not significantly, lower than arterial (P = 0.12), whereas labeled triglyceride concentrations were significantly lower in the coronary sinus than in the artery (P < 0.05; extraction fraction congruent with 11%). Triglycerides and FFAs accounted for approximately 17% and approximately 83%, respectively, of myocardial fatty acid uptake. Systemic and myocardial fractional spillover of LPL-generated fatty acids was 49.0 +/- 7% and 34.7 +/- 13%, respectively. The myocardium was a minor contributor to systemic triglyceride uptake ( approximately 3%) and a trivial contributor to systemic FFA production ( approximately 0.5%). These results indicate that circulating triglycerides may be a significant source of fatty acids for myocardial respiration.
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Affiliation(s)
- Robert H Nelson
- Endocrine Research Unit, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
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292
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Di Bello V, Santini F, Di Cori A, Pucci A, Palagi C, Delle Donne MG, Giannetti M, Talini E, Nardi C, Pedrizzetti G, Fierabracci P, Vitti P, Pinchera A, Balbarini A. Relationship between preclinical abnormalities of global and regional left ventricular function and insulin resistance in severe obesity: a Color Doppler Imaging Study. Int J Obes (Lond) 2007; 30:948-56. [PMID: 16446750 DOI: 10.1038/sj.ijo.0803206] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
BACKGROUND The aim of this study was to evaluate the relationship between insulin resistance and preclinical abnormalities of the left ventricular structure and function detected in severe obesity by Color Doppler Myocardial Imaging (CDMI). Forty-eight consecutive severely obese patients (Group O) (11 males, 37 females, mean age 32.8+/-7 years) were enrolled. Forty-eight sex- and age-matched non-obese healthy subjects were also recruited as controls (Group C). All subjects underwent conventional 2D-Color Doppler echocardiography and CDMI. The homeostasis model assessment insulin resistance index (HOMA-IR) was used to assess insulin resistance results. Obese subjects had a greater left ventricular mass index (by height) (58.8+/-14 g/m(2.7)) than controls (37+/-8 g/m(2.7)) (P<0.0001), owing to compensation response to volume overload caused by a greater cardiac output (P<0.02). Preload reserve was increased in obese subjects, as demonstrated by a significant increase in left atrial dimension (P<0.0001). Obese patients had a slightly reduced LV diastolic function (transmitral E/A ratio: Group O, 1.1+/-0.8 vs Group C, 1.5 +/-0.5; P<0.002). Cardiac deformation assessed by regional myocardial systolic strain and strain rate (SR) values was significantly lower (abnormal) in obese patients than in controls, both at the septum and lateral wall level. These strain and SR abnormalities were significantly related to body mass index. In addition, the early phase of diastolic function, evaluated using SR, was compromised in obese patients (P<0.001). The HOMA-IR values in obese patients were significantly higher (3.09+/-1.6) than those determined in the control group (0.92+/-0.5) (P<0.0001). The HOMA-IR values, in the obese group, were significantly related to systolic strain and SR values sampled at the septum level (P<0.0001). CONCLUSION In conclusion, this study has demonstrated that obese patients pointed out systolic structural and functional abnormalities at a preclinical stage, in particular through strain and SR analysis; on the other hand, those altered CDMI parameters well distinguish obese subjects as compared with the control group. Furthermore, another main finding of the study was that myocardial deformation (systolic strain) could have a correlation with insulin resistance level.
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Affiliation(s)
- V Di Bello
- Cardiac and Thoracic Department, University of Pisa, Pisa, Italy.
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293
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Abstract
Obesity increases the risk of cardiovascular disease and premature death. Adipose tissue releases a large number of bioactive mediators that influence not only body weight homeostasis but also insulin resistance - the core feature of type 2 diabetes - as well as alterations in lipids, blood pressure, coagulation, fibrinolysis and inflammation, leading to endothelial dysfunction and atherosclerosis. We are now beginning to understand the underlying mechanisms as well as the ways in which smoking and dyslipidaemia increase, and physical activity attenuates, the adverse effects of obesity on cardiovascular health.
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Affiliation(s)
- Luc F Van Gaal
- University of Antwerp, Faculty of Medicine, Department of Diabetology, Metabolism and Clinical Nutrition, Antwerp University Hospital, Wilrijkstraat 10, B-2650 Edegem, Belgium.
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294
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Velan SS, Durst C, Lemieux SK, Raylman RR, Sridhar R, Spencer RG, Hobbs GR, Thomas MA. Investigation of muscle lipid metabolism by localized one- and two-dimensional MRS techniques using a clinical 3T MRI/MRS scanner. J Magn Reson Imaging 2007; 25:192-9. [PMID: 17152056 DOI: 10.1002/jmri.20786] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
PURPOSE To demonstrate the feasibility of estimating the relative intra- and extramyocellular lipid (IMCL and EMCL) pool magnitudes and calculating the degree of lipid unsaturation within soleus muscle using single-voxel localized one- and two-dimensional (1D and 2D) MR spectroscopy (MRS). MATERIALS AND METHODS Localized 1D point resolved spectroscopy (PRESS) and 2D correlation spectroscopy (L-COSY) were performed in identical locations in the soleus muscle of 10 healthy subjects. A GE 3-T MRI/MRS scanner and a quadrature extremity transmit/receive coil was used. RESULTS The 1D and 2D MR spectra were used to compute IMCL/creatine (Cr) and EMCL/Cr ratios. In addition to cross peaks between the methyl and methylene protons in the high-field region, the 2D spectra showed cross peaks due to J-coupling between allylic, diallylic methylene pro- tons, and olefinic protons. The cross-peak volume ratios also provided a measure of double bonds, suggesting that this ratio can be used to assess unsaturation within IMCL and EMCL lipid pools. CONCLUSION We have demonstrated the feasibility of detecting 2D cross peaks between different groups of IMCL and EMCL, including the unsaturated protons within these two lipids pools. This protocol may be easily extended to study the lipids present in other tissues.
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Affiliation(s)
- S Sendhil Velan
- Center for Advanced Imaging and Radiology, West Virginia University, Morgantown, West Virginia 26506, USA.
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295
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Lamant M, Smih F, Harmancey R, Philip-Couderc P, Pathak A, Roncalli J, Galinier M, Collet X, Massabuau P, Senard JM, Rouet P. ApoO, a novel apolipoprotein, is an original glycoprotein up-regulated by diabetes in human heart. J Biol Chem 2006; 281:36289-302. [PMID: 16956892 DOI: 10.1074/jbc.m510861200] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Obesity is an independent risk factor for cardiac failure. Obesity promotes excessive deposition of fat in adipose and nonadipose tissues. Intramyocardial lipid overload is a relatively common finding in nonischemic heart failure, especially in obese and diabetic patients, and promotes lipoapoptosis that contributes to the alteration of cardiac function. Lipoprotein production has been proposed as a heart-protective mechanism through the unloading of surplus cellular lipids. We previously analyzed the heart transcriptome in a dog nutritional model of obesity, and we identified a new apolipoprotein, regulated by obesity in heart, which is the subject of this study. We detected this new protein in the following lipoproteins: high density lipoprotein, low density lipoprotein, and very low density lipoprotein. We designated it apolipoprotein O. Apolipoprotein O is a 198-amino acid protein that contains a 23-amino acidlong signal peptide. The apolipoprotein O gene is expressed in a set of human tissues. Confocal immunofluorescence microscopy colocalized apolipoprotein O and perilipins, a cellular marker of the lipid droplet. Chondroitinase ABC deglycosylation analysis or cell incubation with p-nitrophenyl-beta-d-xyloside indicated that apolipoprotein O belongs to the proteoglycan family. Naringenin or CP-346086 treatments indicated that apolipoprotein O secretion requires microsomal triglyceride transfer protein activity. Apolipoprotein O gene expression is up-regulated in the human diabetic heart. Apolipoprotein O promoted cholesterol efflux from macrophage cells. To our knowledge, apolipoprotein O is the first chondroitin sulfate chain containing apolipoprotein. Apolipoprotein O may be involved in myocardium-protective mechanisms against lipid accumulation, or it may have specific properties mediated by its unique glycosylation pattern.
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Affiliation(s)
- Matthieu Lamant
- Unité de Recherches sur les Obésités, INSERM UPS U586, Institut Louis Bugnard IFR31, CHU Rangueil, Batiment L3, BP 84225, 31432 Toulouse Cedex 4, France
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296
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Kankaanpää M, Lehto HR, Pärkkä JP, Komu M, Viljanen A, Ferrannini E, Knuuti J, Nuutila P, Parkkola R, Iozzo P. Myocardial triglyceride content and epicardial fat mass in human obesity: relationship to left ventricular function and serum free fatty acid levels. J Clin Endocrinol Metab 2006; 91:4689-95. [PMID: 16926257 DOI: 10.1210/jc.2006-0584] [Citation(s) in RCA: 248] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
CONTEXT AND OBJECTIVE Ectopic fat accumulation within and around the myocardial wall has been implicated in the pathogenesis of heart disease in obesity. We evaluated myocardial and epicardial fat, left ventricular (LV) function, and metabolic risk factors in nine (five lean, four moderately obese) men. METHODS Myocardial fat percent was quantified in the septum by proton magnetic resonance spectroscopy. Reproducibility was assessed by triplicate systolic and diastolic measurements. LV parameters and epicardial fat were determined by magnetic resonance imaging. Waist-to-hip ratio and liver enzymes (alanine transaminase) were used as surrogate markers of visceral and liver fat contents. RESULTS Myocardial fat (2.1 +/- 0.5 vs. 0.8 +/- 0.1, P = 0.03) and epicardial fat (120 +/- 33 vs. 55 +/- 12 g, P = 0.08) were higher in obese than lean subjects. Individuals with above-median alanine transaminase values had a 4-fold elevation in myocardial fat. The coefficient of variation of repeated myocardial fat percent determinations was 17 +/- 3 and 23 +/- 3% in systole and diastole, respectively. Myocardial fat was correlated with free fatty acid (FFA) levels (r = 0.76; P = 0.017), epicardial fat (r = 0.69; P = 0.042), and waist-to-hip ratio (r = 0.70; P = 0.035), and it showed a tendency to associate positively with LV work. Epicardial fat was associated with peripheral vascular resistance (positively) and the cardiac index (negatively). FFA levels were significantly correlated with LV mass (r = 0.72; P = 0.030) and forward work (r = 0.74; P = 0.023). CONCLUSIONS/INTERPRETATION The accumulation of triglyceride in and around the myocardium of moderately obese individuals is significant, and it is related to FFA exposure, generalized ectopic fat excess, and peripheral vascular resistance. These changes precede LV overload and hypertrophy.
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Affiliation(s)
- Mikko Kankaanpää
- Turku PET Centre, University of Turku, FIN-20521, Turku, Finland
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297
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Iacobellis G, Pond CM, Sharma AM. Different "weight" of cardiac and general adiposity in predicting left ventricle morphology. Obesity (Silver Spring) 2006; 14:1679-84. [PMID: 17062795 DOI: 10.1038/oby.2006.192] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Excess adiposity has been widely related to cardiac morphological changes. Nevertheless, the mechanistic link between increased adiposity and left ventricular (LV) morphology is controversial and not completely understood. In this context, several authors have recently debated the different "weight" of BMI as an index of general adiposity vs. the importance of the epicardial fat depot as a marker of local visceral adiposity in obesity-related LV changes. Studies in uncomplicated obesity suggest that the role of BMI in predicting LV abnormalities remains rather doubtful. In contrast, several lines of evidence suggest that cardiac adiposity could play an important part in the development of cardiac modifications. Epicardial fat as an index of cardiac adiposity could have a functional and mechanical role in obesity-related LV abnormalities. Epicardial fat is clinically correlated with LV mass, atrial dimensions, and diastolic function, but a causal effect of epicardial adipose tissue on cardiac chamber modifications remains to be demonstrated. Nevertheless, the close anatomical and functional relationship of epicardial adipose tissue to the adjacent myocardium should readily allow local, paracrine interactions between these tissues.
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Affiliation(s)
- Gianluca Iacobellis
- Department of Medicine, Cardiovascular Obesity Research and Management, Michael G. deGroote School of Medicine, Hamilton, Ontario, Canada.
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298
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Boudina S, Abel ED. Mitochondrial uncoupling: a key contributor to reduced cardiac efficiency in diabetes. Physiology (Bethesda) 2006; 21:250-8. [PMID: 16868314 DOI: 10.1152/physiol.00008.2006] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Cardiovascular disease is the primary cause of death in individuals with obesity and diabetes. However, the underlying mechanisms for cardiac dysfunction are partially understood. Studies have suggested that altered cardiac metabolism may play a role. The diabetic heart is characterized by increased fatty acid oxidation, increased myocardial oxygen consumption, and reduced cardiac efficiency. Here, we review possible mechanisms for reduced cardiac efficiency in obesity and diabetes by focusing on the potential role of mitochondrial uncoupling.
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Affiliation(s)
- Sihem Boudina
- Division of Endocrinology, Metabolism, and Diabetes, and Program in Human Molecular Biology and Genetics, University of Utah School of Medicine, Salt Lake City, Utah, USA
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299
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Thakker GD, Frangogiannis NG, Bujak M, Zymek P, Gaubatz JW, Reddy AK, Taffet G, Michael LH, Entman ML, Ballantyne CM. Effects of diet-induced obesity on inflammation and remodeling after myocardial infarction. Am J Physiol Heart Circ Physiol 2006; 291:H2504-14. [PMID: 16731644 DOI: 10.1152/ajpheart.00322.2006] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Epidemiological studies indicate that obesity, insulin resistance, and diabetes are important comorbidities of patients with ischemic heart disease and increase mortality and development of congestive heart failure after myocardial infarction. Although ob/ob and db/db mice are commonly used to study obesity with insulin resistance or diabetes, mutations in the leptin gene or its receptor are rarely the cause of obesity in humans, which is, instead, primarily a consequence of dietary and lifestyle factors. Therefore, we used a murine model of diet-induced obesity to examine the physiological effects of obesity and the inflammatory and healing response of diet-induced obese (DIO) mice after myocardial ischemia-reperfusion injury. DIO mice developed hyperinsulinemia and insulin resistance and hepatic steatosis, with significant ectopic lipid deposition in the heart and cardiac hypertrophy in the absence of significant changes in blood pressure. The mRNA levels of chemokines at 24 h and cytokines at 24 and 72 h of reperfusion were higher in DIO than in lean mice. In granulation tissue at 72 h of reperfusion, macrophage density was significantly increased, whereas neutrophil density was reduced, in DIO mice compared with lean mice. At 7 days of reperfusion, collagen deposition in the scar was significantly reduced and left ventricular (LV) dilation and cardiac hypertrophy were increased, indicative of adverse LV remodeling, in infarcted DIO mice. Characterization of a murine diet-induced model of obesity and insulin resistance that satisfies many aspects commonly observed in human obesity allows detailed examination of the adverse cardiovascular effects of diet-induced obesity at the molecular level.
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Affiliation(s)
- Geeta D Thakker
- Dept. of Medicine, Baylor College of Medicine, 6565 Fannin, M.S. A-601, Houston, TX 77030, USA
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300
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de las Fuentes L, Waggoner AD, Brown AL, Dávila-Román VG. Plasma triglyceride level is an independent predictor of altered left ventricular relaxation. J Am Soc Echocardiogr 2006; 18:1285-91. [PMID: 16376756 DOI: 10.1016/j.echo.2005.05.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2005] [Indexed: 01/22/2023]
Abstract
BACKGROUND Diastolic dysfunction, manifested by impaired left ventricular (LV) relaxation, is prevalent among individuals with metabolic disorders. The objective of this study was to evaluate the extent to which plasma triglyceride (TG) levels are related to LV diastolic function. METHODS A total of 424 subjects (age 49 +/- 12 years) had fasting plasma TG levels measured and underwent echocardiography for assessment of LV structure and function: LV ejection fraction and LV mass indexed to height (LVM/Ht(2.7)); transmitral inflow early diastolic peak velocity (E wave) and late diastolic peak velocity (A wave), and E wave to A wave ratio (E/A); deceleration time; and Doppler tissue imaging early diastolic myocardial velocity (EM), an index of LV relaxation. RESULTS All subjects had normal LV ejection fraction, 48% had hypertension, 16% had increased LVM/Ht(2.7), 11% had type 2 diabetes mellitus, 37% were obese, and 27% had hypertriglyceridemia (TG > 150 mg/dL). Univariate analysis showed significant relationships between TG level and E/A, deceleration time, and Em (P < or = .001 for all). After adjustment for potential confounders in multivariate models (eg, age, systolic blood pressure, and LVM/Ht(2.7)), TG levels remained predictive of E/A, deceleration time, and Em (P < or = .05, <.001, and < or =.0001, respectively). Stepwise multivariate analysis showed that after age and body mass index, the TG level was the next most predictive variable of Em. CONCLUSIONS Plasma TG levels show a strong relationship with impaired LV relaxation, an early marker of diastolic dysfunction in human beings. These findings support a hypothesis whereby elevated TG levels favor myocyte intracellular lipid accumulation, possibly leading to lipotoxic diastolic dysfunction.
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Affiliation(s)
- Lisa de las Fuentes
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St Louis, Missouri 63110, USA.
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