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Rasouli N, Younes N, Utzschneider KM, Inzucchi SE, Balasubramanyam A, Cherrington AL, Ismail-Beigi F, Cohen RM, Olson DE, DeFronzo RA, Herman WH, Lachin JM, Kahn SE. Association of Baseline Characteristics With Insulin Sensitivity and β-Cell Function in the Glycemia Reduction Approaches in Diabetes: A Comparative Effectiveness (GRADE) Study Cohort. Diabetes Care 2021; 44:340-349. [PMID: 33334808 PMCID: PMC7818323 DOI: 10.2337/dc20-1787] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 11/11/2020] [Indexed: 02/03/2023]
Abstract
OBJECTIVE We investigated sex and racial differences in insulin sensitivity, β-cell function, and glycated hemoglobin (HbA1c) and the associations with selected phenotypic characteristics. RESEARCH DESIGN AND METHODS This is a cross-sectional analysis of baseline data from 3,108 GRADE (Glycemia Reduction Approaches in Diabetes: A Comparative Effectiveness Study) participants. All had type 2 diabetes diagnosed <10 years earlier and were on metformin monotherapy. Insulin sensitivity and β-cell function were evaluated using the HOMA of insulin sensitivity and estimates from oral glucose tolerance tests, including the Matsuda Index, insulinogenic index, C-peptide index, and oral disposition index (DI). RESULTS The cohort was 56.6 ± 10 years of age (mean ± SD), 63.8% male, with BMI 34.2 ± 6.7 kg/m2, HbA1c 7.5 ± 0.5%, and type 2 diabetes duration 4.0 ± 2.8 years. Women had higher DI than men but similar insulin sensitivity. DI was the highest in Black/African Americans, followed by American Indians/Alaska Natives, Asians, and Whites in descending order. Compared with Whites, American Indians/Alaska Natives had significantly higher HbA1c, but Black/African Americans and Asians had lower HbA1c. However, when adjusted for glucose levels, Black/African Americans had higher HbA1c than Whites. Insulin sensitivity correlated inversely with BMI, waist-to-hip ratio, triglyceride-to-HDL-cholesterol ratio (TG/HDL-C), and the presence of metabolic syndrome, whereas DI was associated directly with age and inversely with BMI, HbA1c, and TG/HDL-C. CONCLUSIONS In the GRADE cohort, β-cell function differed by sex and race and was associated with the concurrent level of HbA1c. HbA1c also differed among the races, but not by sex. Age, BMI, and TG/HDL-C were associated with multiple measures of β-cell function and insulin sensitivity.
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Affiliation(s)
- Neda Rasouli
- Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, University of Colorado School of Medicine, Aurora, CO
- VA Eastern Colorado Health Care System, Aurora, CO
| | - Naji Younes
- The Biostatistics Center, Department of Biostatistics and Bioinformatics, Milken Institute School of Public Health, The George Washington University, Rockville, MD
| | - Kristina M Utzschneider
- Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, VA Puget Sound Health Care System and the University of Washington, Seattle, WA
| | | | - Ashok Balasubramanyam
- Division of Diabetes, Endocrinology and Metabolism, Baylor College of Medicine, Houston, TX
| | | | - Faramarz Ismail-Beigi
- Department of Medicine, Case Western Reserve University and Louis Stokes Cleveland VA Medical Center, Cleveland, OH
| | - Robert M Cohen
- Division of Endocrinology, Diabetes and Metabolism, University of Cincinnati College of Medicine and Cincinnati VA Medical Center, Cincinnati, OH
| | - Darin E Olson
- Atlanta VA Health Care System and Division of Endocrinology, Metabolism, and Lipids, Department of Medicine, Emory University School of Medicine, Atlanta, GA
| | - Ralph A DeFronzo
- University of Texas Health Science Center at San Antonio, San Antonio, TX
| | - William H Herman
- Departments of Internal Medicine and Epidemiology, University of Michigan, Ann Arbor, MI
| | - John M Lachin
- The Biostatistics Center, Department of Biostatistics and Bioinformatics, Milken Institute School of Public Health, The George Washington University, Rockville, MD
| | - Steven E Kahn
- Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, VA Puget Sound Health Care System and the University of Washington, Seattle, WA
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Bello O, Mohandas C, Shojee-Moradie F, Jackson N, Hakim O, Alberti KGMM, Peacock JL, Umpleby AM, Amiel SA, Goff LM. Black African men with early type 2 diabetes have similar muscle, liver and adipose tissue insulin sensitivity to white European men despite lower visceral fat. Diabetologia 2019; 62:835-844. [PMID: 30729259 PMCID: PMC6450859 DOI: 10.1007/s00125-019-4820-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 12/27/2018] [Indexed: 01/11/2023]
Abstract
AIMS/HYPOTHESIS Type 2 diabetes is more prevalent in black African than white European populations although, paradoxically, black African individuals present with lower levels of visceral fat, which has a known association with insulin resistance. Insulin resistance occurs at a tissue-specific level; however, no study has simultaneously compared whole body, skeletal muscle, hepatic and adipose tissue insulin sensitivity between black and white men. We hypothesised that, in those with early type 2 diabetes, black (West) African men (BAM) have greater hepatic and adipose tissue insulin sensitivity, compared with white European men (WEM), because of their reduced visceral fat. METHODS Eighteen BAM and 15 WEM with type 2 diabetes underwent a two-stage hyperinsulinaemic-euglycaemic clamp with stable glucose and glycerol isotope tracers to assess tissue-specific insulin sensitivity and a magnetic resonance imaging scan to assess body composition. RESULTS We found no ethnic differences in whole body, skeletal muscle, hepatic or adipose tissue insulin sensitivity between BAM and WEM. This finding occurred in the presence of lower visceral fat in BAM (3.72 vs 5.68 kg [mean difference -1.96, 95% CI -3.30, 0.62]; p = 0.01). There was an association between skeletal muscle and adipose tissue insulin sensitivity in WEM that was not present in BAM (r = 0.78, p < 0.01 vs r = 0.25 p = 0.37). CONCLUSIONS/INTERPRETATION Our data suggest that in type 2 diabetes there are no ethnic differences in whole body, skeletal muscle, hepatic and adipose tissue insulin sensitivity between black and white men, despite differences in visceral adipose tissue, and that impaired lipolysis may not be contributing to skeletal muscle insulin resistance in men of black African ethnicity.
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Affiliation(s)
- Oluwatoyosi Bello
- Department of Diabetes, School of Life Course Sciences, Faculty of Life Sciences & Medicine, King's College London, Franklin-Wilkins Building, Waterloo Campus, London, SE1 9NH, UK
| | - Cynthia Mohandas
- Department of Diabetes, School of Life Course Sciences, Faculty of Life Sciences & Medicine, King's College London, Franklin-Wilkins Building, Waterloo Campus, London, SE1 9NH, UK
| | | | - Nicola Jackson
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | - Olah Hakim
- Department of Diabetes, School of Life Course Sciences, Faculty of Life Sciences & Medicine, King's College London, Franklin-Wilkins Building, Waterloo Campus, London, SE1 9NH, UK
| | - K George M M Alberti
- Department of Diabetes, School of Life Course Sciences, Faculty of Life Sciences & Medicine, King's College London, Franklin-Wilkins Building, Waterloo Campus, London, SE1 9NH, UK
| | - Janet L Peacock
- School of Population Health and Environmental Sciences, King's College London, London, UK
| | - A Margot Umpleby
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | - Stephanie A Amiel
- Department of Diabetes, School of Life Course Sciences, Faculty of Life Sciences & Medicine, King's College London, Franklin-Wilkins Building, Waterloo Campus, London, SE1 9NH, UK
| | - Louise M Goff
- Department of Diabetes, School of Life Course Sciences, Faculty of Life Sciences & Medicine, King's College London, Franklin-Wilkins Building, Waterloo Campus, London, SE1 9NH, UK.
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Nielsen S, Sumner AE, Miller BV, Turkova H, Klein S, Jensen MD. Free fatty acid flux in African-American and Caucasian adults--effect of sex and race. Obesity (Silver Spring) 2013; 21:1836-42. [PMID: 23418014 PMCID: PMC3770799 DOI: 10.1002/oby.20322] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Accepted: 11/29/2012] [Indexed: 12/31/2022]
Abstract
OBJECTIVE Obesity, insulin resistance, and diabetes disproportionately affect African-American (AA) women. Abnormal adipose tissue free fatty acid (FFA) release is associated with these conditions. Resting energy expenditure (REE) and sex predict FFA release in Caucasians, but whether this is true in AA is unknown. The sex-specific relationships between FFA release, REE, and race was compared. DESIGN AND METHODS 100 adults (47% AA, 50% male, age 32 ± 8 years [mean ± SD]) from three different centers underwent duplicate measures of FFA release ([U-13C] palmitate) and REE (indirect calorimetry). Body composition was determined by DXA and abdominal imaging. RESULTS AA participants had lower REE, but similar FFA concentrations and flux compared with Caucasian participants. The significant predictors of palmitate release were REE, sex, and race. REE and FFA flux were correlated in both sexes and both races. In a multiple linear regression analysis with palmitate flux as the dependent variable and REE, sex, race, total fat mass, fat-free mass, and insulin as independent variables, REE was the only independent predictor of FFA release in men. Both REE and race predicted palmitate flux in women. CONCLUSIONS FFA flux is related to REE, but the relationship differs in AA and Caucasian women.
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Affiliation(s)
- Søren Nielsen
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark
- Endocrine Research Unit, Mayo Clinic, Rochester, MN, USA
| | - Anne E. Sumner
- Diabetes, Endocrinology and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institute of Health, Bethesda, MA, USA
| | - Bernard V. Miller
- Diabetes, Endocrinology and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institute of Health, Bethesda, MA, USA
- Center for Human Nutrition and Atkins Center of Excellence in Obesity Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Hana Turkova
- National Institute of Child Health and Development
| | - Samuel Klein
- Center for Human Nutrition and Atkins Center of Excellence in Obesity Medicine, Washington University School of Medicine, St. Louis, MO, USA
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Goedecke JH, Levitt NS, Evans J, Ellman N, Hume DJ, Kotze L, Tootla M, Victor H, Keswell D. The role of adipose tissue in insulin resistance in women of African ancestry. J Obes 2013; 2013:952916. [PMID: 23401754 PMCID: PMC3557633 DOI: 10.1155/2013/952916] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Accepted: 12/13/2012] [Indexed: 01/01/2023] Open
Abstract
Women of African ancestry, particularly those living in industrialized countries, experience a disproportionately higher prevalence of type 2 diabetes (T2D) compared to their white counterparts. Similarly, obesity and insulin resistance, which are major risk factors for T2D, are greater in black compared to white women. The exact mechanisms underlying these phenomena are not known. This paper will focus on the role of adipose tissue biology. Firstly, the characteristic body fat distribution of women of African ancestry will be discussed, followed by the depot-specific associations with insulin resistance. Factors involved in adipose tissue biology and their relation to insulin sensitivity will then be explored, including the role of sex hormones, glucocorticoid metabolism, lipolysis and adipogenesis, and their consequent effects on adipose tissue hypoxia, oxidative stress, and inflammation. Finally the role of ectopic fat deposition will be discussed. The paper proposes directions for future research, in particular highlighting the need for longitudinal and/or intervention studies to better understand the mechanisms underlying the high prevalence of insulin resistance and T2D in women of African ancestry.
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Affiliation(s)
- Julia H Goedecke
- UCT/MRC Research Unit for Exercise Science and Sports Medicine, South African Medical Research Council, Parow, Cape Town 7505, South Africa.
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Miller BV, Patterson BW, Okunade A, Klein S. Fatty acid and very low density lipoprotein metabolism in obese African American and Caucasian women with type 2 diabetes. J Lipid Res 2012; 53:2767-72. [PMID: 23048205 DOI: 10.1194/jlr.p030593] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Type 2 diabetes mellitus (T2DM) is associated with increased plasma triglyceride (TG) concentrations, but African Americans (AA) have lower plasma TG than Caucasians (CC). We evaluated the hypothesis that obese AA women have lower plasma TG than obese CC women do because of differences in lipid kinetics. Eleven AA and 11 CC obese women with T2DM, matched on body mass index (BMI) (AA = 37 ± 1, CC = 37 ± 1 kg/m(2)), age, duration of diabetes, percentage body fat, and insulin sensitivity (S(I), determined by an intravenous glucose tolerance test), were studied. Plasma TG concentration (AA = 1.14 ± 0.11, CC = 1.88 ± 0.18 mmol/l), FFA rate of appearance (R(a)) into plasma (AA = 419 ± 27, CC = 503 ± 31 µmol·min(-1)), and total VLDL-TG secretion rate (AA = 18 ± 2, CC = 29 ± 4 µmol·min(-1)) were lower in AA than CC women (all P < 0.05). In contrast, plasma total apolipoprotein (apo)B-100 concentration (AA = 1,542 ± 179, CC = 1,620 ± 118 nmol/l) and VLDL-apoB-100 secretion rate (AA = 1.3 ± 0.1, CC = 1.3 ± 0.1 nmol·min(-1)) were similar in both groups, so the molar ratio of VLDL-TG secretion rate to VLDL-apoB-100 secretion rate was lower in AA women than in CC women. VLDL-TG concentration was lower in AA women due to lower total VLDL-TG secretion rate. However, the VLDL-apoB-100 secretion rate was the same in both groups, demonstrating that AA women secrete smaller VLDL particles containing less TG than do CC women.
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Affiliation(s)
- Bernard V Miller
- Center for Human Nutrition and Atkins Center of Excellence in Obesity Medicine, Washington University School of Medicine, Saint Louis, MO 63110, USA
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McGill JB, Peterson LR, Herrero P, Saeed IM, Recklein C, Coggan AR, DeMoss AJ, Schechtman KB, Dence CS, Gropler RJ. Potentiation of abnormalities in myocardial metabolism with the development of diabetes in women with obesity and insulin resistance. J Nucl Cardiol 2011; 18:421-9; quiz 432-3. [PMID: 21516378 PMCID: PMC3811030 DOI: 10.1007/s12350-011-9362-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2009] [Accepted: 02/16/2011] [Indexed: 01/22/2023]
Abstract
BACKGROUND Because studies in animal models of type-2 diabetes mellitus (DM) show that excessive myocardial fatty acid (FA) metabolism (at the expense of glucose metabolism) cause cardiac dysfunction, we hypothesized that women with DM would have more FA and less glucose myocardial metabolism than normal or even obese (OB) women. RESEARCH DESIGN AND METHODS Women who were lean volunteers (NV) (N = 14; age 35 ± 17 years, body mass index 23 ± 1 kg/m(2)), OB (N = 28;31 ± 6 years, BMI 39 ± 7 kg/m2), and DM (n = 22; 54 ± 11 years, BMI 38 ± 5 kg/m2) were studied. Cardiac positron emission tomography was performed for the determination of myocardial blood flow, oxygen consumption, FA and glucose metabolism. Cardiac work was measured by echocardiography and efficiency by the ratio of work to myocardial oxygen consumption. RESULTS Fractional glucose uptake was comparable between NV and OB but lower in DM (P < .05 versus NV). Myocardial FA utilization and oxidation were both higher in DM compared with NV and OB (P < .0001). Myocardial FA utilization and oxidation had positive correlations with HOMA (R = 0.35, P = .005 and R = 0.40, P = .001, respectively) whereas fractional glucose uptake exhibited an inverse correlation (R = -.31, P = .01). Cardiac work and efficiency were similar among the three groups. CONCLUSIONS In women, the presence of OB and DM compared with OB alone is associated with a greater reliance on myocardial FA metabolism at the expense of glucose metabolism. These perturbations in myocardial metabolism are not associated in a decline left ventricular efficiency or function suggesting that the metabolic perturbations may precede an eventual decline left ventricular function as is seen in animal models of DM.
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Affiliation(s)
- Janet B. McGill
- Division of Endocrinology, Metabolism and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Linda R. Peterson
- Division of Cardiovascular Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO
- Division of Radiological Sciences, Edward Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO
| | - Pilar Herrero
- Division of Radiological Sciences, Edward Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO
| | - Ibrahim M. Saeed
- Division of Cardiovascular Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Carol Recklein
- Division of Endocrinology, Metabolism and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Andrew R. Coggan
- Division of Radiological Sciences, Edward Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO
| | - Amanda J. DeMoss
- Division of Radiological Sciences, Edward Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO
| | | | - Carmen S. Dence
- Division of Radiological Sciences, Edward Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO
| | - Robert J. Gropler
- Division of Cardiovascular Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO
- Division of Radiological Sciences, Edward Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO
- Cardiovascular Imaging Laboratory, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO
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Hasson RE, Granados K, Chipkin S, Freedson PS, Braun B. Effects of a single exercise bout on insulin sensitivity in black and white individuals. J Clin Endocrinol Metab 2010; 95:E219-23. [PMID: 20631019 DOI: 10.1210/jc.2010-0019] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND Previous research suggests non-Hispanic blacks (blacks) are more insulin resistant than non-Hispanic whites (whites). Physical activity can play an important role in reducing insulin resistance. However, it is unknown whether racial differences exist in response to exercise. Therefore, the purpose of this study was to compare metabolic responses to a single bout of exercise in blacks and age-, sex-, and body mass index-matched whites. METHODS Whole-body insulin sensitivity, glucose storage, glucose oxidation, and respiratory exchange ratio (RER) were assessed during a hyperinsulinemic-euglycemic clamp in normoglycemic blacks (n = 11) and whites (n = 10). Outcome measures were evaluated in a sedentary control condition and 12 h after treadmill walking at 75% of maximal heart rate for 75 min. RESULTS In the control condition, there were no differences in insulin sensitivity between blacks and whites (P = 0.54). During the clamp, glucose oxidation and insulin-stimulated RER values were significantly higher in blacks compared with whites (P = 0.04 and P < 0.01, respectively). Despite similar RER values during exercise, RER values at 60, 90, and 120 min after exercise in blacks were also significantly higher compared with whites (P < 0.05). After exercise, there were no significant improvements in insulin sensitivity (P = 0.57) or glucose storage (P = 0.42) in blacks or whites; however, glucose oxidation was significantly lower in both racial groups (P < 0.05). CONCLUSIONS These data suggest that insulin sensitivity is similar in blacks and age-, sex-, and body mass index-matched whites, but the glucose disposal pathways (storage vs. oxidation) are somewhat different. Compared with whites, blacks appear to have a greater capacity to increase glucose oxidation immediately after exercise and during insulin stimulation.
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Affiliation(s)
- Rebecca E Hasson
- University of Massachusetts Amherst, Department of Kinesiology, Amherst, Massachusetts 01003, USA
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Fried SK, Tittelbach T, Blumenthal J, Sreenivasan U, Robey L, Yi J, Khan S, Hollender C, Ryan AS, Goldberg AP. Resistance to the antilipolytic effect of insulin in adipocytes of African-American compared to Caucasian postmenopausal women. J Lipid Res 2009; 51:1193-200. [PMID: 19965580 DOI: 10.1194/jlr.p000935] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
High fatty acid (FA) flux is associated with systemic insulin resistance, and African-American (AA) women tend to be more insulin resistant. We assessed possible depot and race difference in the antilipolytic effect of insulin in adipocytes isolated from abdominal (Abd) and gluteal (Glt) subcutaneous (sc) adipose tissue of overweight, postmenopausal AA and Caucasian (C) women. Percent body fat, fasting insulin, visceral adiposity, and adipocyte size was higher in AA women. Disinhibited lipolysis (presence of adenosine deaminase) per unit adipocyte surface area was similar in Abd and Glt and in AA and C. However, rates of 'basal' [submaximal phenylisopropyl adenosine (PIA)-suppressed] and insulin-suppressed lipolysis were higher in Abd of AA compared with C women even after adjustment for percent fat and visceral fat area. The race difference in rates of PIA- and insulin-suppressed lipolysis in AA were correlated with their hyperinsulinemia, but AA race, independent of fasting insulin, was associated with lower responsiveness (percent suppression) to submaximal insulin concentrations, although sensitivity (ED50) was not affected. Overall, these data are consistent with the hypothesis that decreased responsiveness of Abd adipocytes to antilipolytic effectors may contribute to higher FA availability and thereby to racial differences in insulin resistance.
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Affiliation(s)
- Susan K Fried
- Geriatric Research and Education Clinical Center, Baltimore Veterans Administration Medical Center, Baltimore, MD, USA.
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Mittendorfer B, Magkos F, Fabbrini E, Mohammed BS, Klein S. Relationship between body fat mass and free fatty acid kinetics in men and women. Obesity (Silver Spring) 2009; 17:1872-7. [PMID: 19629053 PMCID: PMC3319738 DOI: 10.1038/oby.2009.224] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
An increased release of free fatty acids (FFAs) into plasma likely contributes to the metabolic complications associated with obesity. However, the relationship between body fat and FFA metabolism is unclear because of conflicting results from different studies. The goal of our study was to determine the inter-relationships between body fat, sex, and plasma FFA kinetics. We determined FFA rate of appearance (Ra) in plasma, by using stable isotopically labeled tracer techniques, during basal conditions in 106 lean, overweight, and obese, nondiabetic subjects (43 men and 63 women who had 7.0-56.0% body fat). Correlation analyses demonstrated: (i) no differences between men and women in the relationship between fat mass (FM) and total FFA Ra (micromol/min); (ii) total FFA Ra increased linearly with increasing FM (r=0.652, P<0.001); (iii) FFA Ra per kg FM decreased in a curvilinear fashion with increasing FM (r=-0.806; P<0.001); (iv) FFA Ra in relationship to fat-free mass (FFM) was greater in obese than lean subjects and greater in women than in men; and (v) abdominal fat itself was not an important determinant of total FFA Ra. We conclude that total body fat, not regional fat distribution or sex, is an important modulator of the rate of FFA release into plasma. Although increased adiposity is associated with a decrease in fatty acid release in relationship to FM, this downregulation is unable to completely compensate for the increase in FM, so total FFA Ra and FFA Ra with respect to FFM are greater in women than in men and in obese than in lean subjects.
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Affiliation(s)
- Bettina Mittendorfer
- Division of Geriatrics and Nutritional Science and Center for Human Nutrition, Washington University School of Medicine, St Louis, Missouri, USA.
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Scantlebury-Manning T, Bower J, Cianflone K, Barakat H. Racial difference in Acylation Stimulating Protein (ASP) correlates to triglyceride in non-obese and obese African American and Caucasian women. Nutr Metab (Lond) 2009; 6:18. [PMID: 19374759 PMCID: PMC2679015 DOI: 10.1186/1743-7075-6-18] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2008] [Accepted: 04/17/2009] [Indexed: 12/15/2022] Open
Abstract
Background Acylation Stimulating Protein (ASP) has been shown to influence adipose tissue triglyceride (TG) storage. The aim was to examine ethnic differences in ASP and leptin levels in relation to lipid profiles and postprandial changes amongst African American (AA) and Caucasian American (CA) women matched for BMI. Methods 129 women were recruited in total (age 21 – 73 y): 24 non-obese (BMI < 30 kg/m2) CA, 27 obese (BMI ≥ 30 kg/m2) CA, 13 obese diabetic CA, 25 non-obese AA, 25 obese AA, and 15 obese diabetic AA. Cholesterol, HDL-C, LDL-C, apoB, glucose and insulin were measured at baseline. TG, non-esterified fatty acids, leptin, and ASP were measured at baseline and postprandially following a fat meal. Results ASP, leptin, insulin and TG were significantly increased in obese subjects within each race. However, AA women had significantly lower ASP and TG than CA women at all BMI. Obese and diabetic AA women had significantly lower apoB levels than CA women when compared to their respective counterparts. For AA women, fasting ASP was positively correlated with BMI, cholesterol, apoB, LDL-C and glucose. For CA women, fasting ASP was positively correlated with BMI, leptin, glucose and insulin. However, for any given BMI, ASP was significantly reduced in AA vs CA (p = 0.0004). Similarly, for any given leptin level or TG levels, ASP was significantly lower in AA women (p = 0.041 and p = 0.003, respectively). Conclusion CA women have higher baseline TG levels and an earlier TG peak that is accompanied with higher ASP levels suggesting increased ASP resistance, while AA women have lower baseline TG levels and a later TG peak at lower ASP levels suggesting increased ASP sensitivity. This may explain why AA women may have fewer metabolic complications, such as diabetes and CVD, when compared to their Caucasian counterparts at the same level of obesity.
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Affiliation(s)
- Thea Scantlebury-Manning
- Department of Biological and Chemical Sciences, Faculty of Pure and Applied Sciences, University of The West Indies, Cave Hill Campus, Bridgetown, St Michael, Barbados.
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Melanin directly converts light for vertebrate metabolic use: Heuristic thoughts on birds, Icarus and dark human skin. Med Hypotheses 2008; 71:190-202. [DOI: 10.1016/j.mehy.2008.03.038] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2008] [Revised: 03/18/2008] [Accepted: 03/20/2008] [Indexed: 11/22/2022]
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Shankar A, Li J, Klein BEK, Nieto FJ, Klein R. Serum gamma-glutamyltransferase level and peripheral arterial disease. Atherosclerosis 2007; 199:102-9. [PMID: 18037420 DOI: 10.1016/j.atherosclerosis.2007.10.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2007] [Revised: 09/27/2007] [Accepted: 10/12/2007] [Indexed: 10/22/2022]
Abstract
OBJECTIVE We examined the association between increasing serum GGT levels and PAD in the US general population. METHODS Cross-sectional study among 3941 National Health and Nutrition Examination Survey 1999-2002 participants aged >or=40 years. Main outcome-of-interest was PAD defined as ankle-brachial index <0.9 (n=219). RESULTS Overall, serum GGT levels were positively associated with PAD among men but not women (p-interaction=0.0421). Among men, the multivariable odds ratio (OR) [95% confidence intervals (CI)] comparing the highest quartile of serum GGT (>35U/L) to the lowest quartile (<16U/L) was 4.25 (1.65-10.94); p-trend=0.0008. Also the observed positive association between GGT quartiles and PAD among men was predominantly present among non-Hispanic whites and current nondrinkers (multivariable OR [95% CI] comparing the highest quartile of serum GGT to the lowest quartile was 10.59 [2.31-48.55]; p-trend=0.0104). In contrast among women, the multivariable OR (95% CI) comparing the highest quartile of serum GGT to the lowest quartile was 0.76 (0.41-1.41); p-trend=0.8308. CONCLUSIONS There was a positive association between serum GGT level and PAD among men, particularly non-Hispanic white and nondrinker men, but not among women. Future prospective studies are required to clarify the temporal nature of this relationship and to confirm the observed gender-specific nature of this association.
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Affiliation(s)
- Anoop Shankar
- Department of Community, Occupational, and Family Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Block MD3, 16 Medical Drive, Singapore 117597, Singapore.
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Anderson WA, Greene GW, Forse RA, Apovian CM, Istfan NW. Weight loss and health outcomes in African Americans and whites after gastric bypass surgery. Obesity (Silver Spring) 2007; 15:1455-63. [PMID: 17557983 DOI: 10.1038/oby.2007.174] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
OBJECTIVE The objective was to describe differences in weight loss, dietary intake, and cardiovascular risk factors between white and African-American patients after gastric bypass (GBP). RESEARCH METHODS AND PROCEDURES This was a retrospective database review of a sample of 84 adult patients (24 African-American and 60 white women and men) between the ages of 33 and 53 years. All subjects had GBP surgery in 2001 at the Bariatric Surgery Program at Boston Medical Center in Boston, MA, and were followed for one year postoperatively. Patients were excluded if weight data were missing at baseline, 3 months, or 1 year after GBP. A total of 9 African Americans and 41 whites provided data at all 3 time-points and were included in the study. Differences in weight loss, diet, and cardiovascular risk factors were analyzed. RESULTS There were no differences in baseline characteristics between African Americans and whites. Mean weight loss for the entire sample was 36 +/- 9%, with a range of 8% to 54% relative to initial body weight. Whites lost more weight (39 +/- 8%) than African Americans (26 +/- 10%) (p < 0.05). Dietary parameters, as well as improvements in blood pressure and lipid profiles, were similar in the two racial groups. DISCUSSION Differences in weight loss between severely obese African Americans and whites undergoing open GBP are unlikely to be related to postoperative dietary practices. Our data are consistent with previous reports implicating metabolic differences between the two racial groups.
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Affiliation(s)
- Wendy A Anderson
- Section of Endocrinology, Diabetes and Nutrition, Boston Medical Center, Boston, MA 02118, USA
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14
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Mittendorfer B, Liem O, Patterson BW, Miles JM, Klein S. What does the measurement of whole-body fatty acid rate of appearance in plasma by using a fatty acid tracer really mean? Diabetes 2003; 52:1641-8. [PMID: 12829627 DOI: 10.2337/diabetes.52.7.1641] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
We evaluated the validity of using a single fatty acid tracer to assess total plasma long-chain free fatty acid (FFA) kinetics and the relationship between the rate of appearance (R(a)) of fatty acids in plasma and the fatty acid composition of adipose tissue triglyceride (TG). A mixture of [(13)C]-labeled myristate, palmitate, stearate, oleate, and linoleate was infused in healthy men during basal conditions and during conditions that stimulate (epinephrine infusion) and inhibit (insulin infusion) lipolysis of adipose tissue TGs. Calculated total FFA, R(a) based on palmitate, oleate, or linoleate tracers, was within 15% of the measured sum of the individual fatty acid R(a) under all conditions, whereas stearate and myristate tracers consistently underestimated and overestimated total FFA R(a), respectively. The fatty acid R(a) profile closely matched the fatty acid profile of subcutaneous adipose tissue TGs during epinephrine infusion, but not during basal conditions and insulin infusion. Our data support the common practice of using labeled palmitate or oleate as fatty acid tracers for assessing total plasma FFA kinetics and suggest that a source of lipids other than adipose tissue TG release fatty acids into the systemic circulation.
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Affiliation(s)
- Bettina Mittendorfer
- Department of Internal Medicine and Center for Human Nutrition, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Wilfert K, Guski H, Persson PB, Stauss HM. Cardiovascular responses to angiotensin II in atherosclerosis. ACTA PHYSIOLOGICA SCANDINAVICA 2002; 176:95-100. [PMID: 12354168 DOI: 10.1046/j.1365-201x.2002.01025.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Atherosclerosis is associated with increased angiotensin II AT1-receptor expression and vascular hyperresponsiveness to angiotensin II. Nevertheless, atherosclerosis is often not accompanied by hypertension. We studied if the hypertensive effect of angiotensin II is more pronounced in atherosclerosis. Rabbits were fed a high-cholesterol diet (n = 10) for 12 weeks, followed by a standard diet for another 6 weeks. Control animals received the standard diet (n = 8) for 18 weeks. After 18 weeks, haemodynamic measurements were performed during a baseline recording and during an intravenous infusion of angiotensin II (0.4 microg kg-1 min-1). Atherosclerosis in the high-cholesterol group was verified by histological and lipidchemical tissue examinations. During angiotensin II infusion, total peripheral resistance (TPR) increased more in the high-cholesterol group than in controls (+81.6 +/- 12.4 vs. +40.6 +/- 9.7 mmHg min L-1, P < 0.05). While cardiac output and stroke volume (SV) decreased more in the high-cholesterol group (P < 0.05), reflex bradycardia was stronger in the control group (P < 0.05), indicating a reduced baroreceptor reflex sensitivity in atherosclerosis. Despite the larger increase in TPR and the reduced baroreceptor reflex sensitivity in the high-cholesterol group, maximum blood pressure response to angiotensin II was similar in both groups. The lack of a greater blood pressure response to angiotensin II in the high-cholesterol group could be the result of the early stages of heart failure. Under resting conditions, heart failure seems to be fully compensated, as baseline haemodynamic parameters were similar in the high-cholesterol group and in controls. However, during angiotensin II infusion, the compensatory mechanisms do not prevent a stronger fall in cardiac output and SV. Therefore, the blood pressure response to angiotensin II is not exaggerated in atherosclerotic animals, as vascular hyperresponsiveness to angiotensin II is opposed by the stronger fall in cardiac output and SV.
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Affiliation(s)
- K Wilfert
- Johannes-Müller-Institut für Physiologie, Charité, Humboldt-Universität zu Berlin, Berlin, Germany
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