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Nhung BT, Khan NC, Hop LT, Lam NT, Khanh NLB, Lien DTK, Nakamori M, Hien VTT, Kassu A, Yamamoto S. Resting metabolic rate of Vietnamese adolescents. Eur J Clin Nutr 2007; 61:1075-80. [PMID: 17268415 DOI: 10.1038/sj.ejcn.1602629] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE To evaluate the FAO/WHO/UNU equations for predicting resting metabolic rate (RMR) in Vietnamese adolescents. DESIGN A cross-sectional study involving healthy subjects was carried out at the Basic Nutrition Department, National Institute of Nutrition, Vietnam. The RMR was measured by indirect calorimetry and anthropometric indices were recorded. Equations derived by linear regression of RMR and body weight were compared to the FAO/WHO/UNU (1985) predictive equations. SUBJECTS A total of 110 subjects who had normal body mass index (5-85 percentile) and divided into two groups by sex. RESULTS Mean RMRs (MJ/kg/day) were 0.1146+/-0.0054 for males and 0.1062+/-0.0103 for females. Compared to the FAO/WHO/UNU equation, our findings were 7.8% and 11.7% lower in the two groups, respectively (P<0.001). CONCLUSION Our findings suggest that the FAO/WHO/UNU equations may overestimate RMR in Vietnamese adolescents. Further studies on establishing reference of daily energy needs for Vietnamese adolescents should be carried out.
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Affiliation(s)
- B T Nhung
- Department of International Public Health Nutrition, Institute of Health Biosciences, The University of Tokushima, Tokushima, Japan
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Lam NT, Covey SD, Lewis JT, Oosman S, Webber T, Hsu EC, Cheung AT, Kieffer TJ. Leptin resistance following over-expression of protein tyrosine phosphatase 1B in liver. J Mol Endocrinol 2006; 36:163-74. [PMID: 16461936 DOI: 10.1677/jme.1.01937] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Obesity is typically associated with resistance to leptin, yet the mechanism by which leptin signaling becomes impaired is poorly understood. Here we sought to determine if the development of obesity and leptin resistance correlates with increased expression of protein tyrosine phosphatase 1B (PTP1B) in peripheral tissues and whether over-expression of this phosphatase, specifically in liver, could alter the leptin-mediated effects on feeding and glucose metabolism. Obesity was induced in mice through a high-fat diet that resulted in hyperglycemia, hyperinsulinemia and hyperleptinemia. Resistance to leptin was confirmed as exogenous leptin administration reduced food intake in animals on low-fat, but not high-fat diets. Diet-induced resistance to leptin and insulin was associated with increased hepatic levels of PTP1B. Intriguingly, hepatic adenoviral over-expression of PTP1B in ob/ob mice attenuated the ability of exogenous leptin to reduce both plasma glucose levels and food intake. These findings suggest that leptin reduces both plasma glucose and food intake in part through actions on the liver, and hepatic leptin resistance resulting from over-expression of PTP1B may contribute to the development of both diabetes and obesity.
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Affiliation(s)
- N T Lam
- Department of Medicine, University of Alberta, Edmonton, Alberta, Canada
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Abstract
Leptin suppresses insulin secretion by opening ATP-sensitive K(+) (K(ATP)) channels and hyperpolarizing beta-cells. We measured the intracellular concentration of ATP ([ATP](i)) in tumor-derived beta-cells, INS-1, and found that leptin reduced [ATP](i) by approximately 30%, suggesting that the opening of K(ATP) channels by leptin is mediated by decreased [ATP](i). A reduction in glucose availability for metabolism may explain the decreased [ATP](i), since leptin (30 min) reduced glucose transport into INS-1 cells by approximately 35%, compared to vehicle-treated cells. The twofold induction of GLUT2 phosphorylation by GLP-1, an insulin secretagogue, was abolished by leptin. Therefore, the acute effect of leptin could involve covalent modification of GLUT2. These findings suggest that leptin may inhibit insulin secretion by reducing [ATP](i) as a result of reduced glucose availability for the metabolic pathway. In addition, leptin reduced glucose transport by 35% in isolated rat hepatocytes that also express GLUT2, suggesting that glucose transport may also be altered by leptin in other glucose-responsive tissues such as the liver.
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Affiliation(s)
- N T Lam
- Department of Medicine, University of Alberta, Edmonton, Alberta, Canada
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Lam NT, Kieffer TJ. The multifaceted potential of glucagon-like peptide-1 as a therapeutic agent. MINERVA ENDOCRINOL 2002; 27:79-93. [PMID: 11961501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Glucagon-like peptide-1 (GLP-1), an intestinal gut hormone, is rapidly emerging as a new therapeutic agent for the treatment of diabetes mellitus. GLP-1, released from intestinal L-cells, is renowned for its potent stimulation of insulin biosynthesis and release from pancreatic b-cells. Exogenous administration of GLP-1 to subjects with type 2 diabetes results in the normalization of plasma glucose concentrations, in part, as a result of augmented glucose-stimulated insulin secretion. However, it is now recognized that GLP-1 has several other anti-diabetic actions that collectively improve the type 2 diabetic phenotype, and may also prove beneficial in the treatment of type 1 diabetes. These effects include the deceleration of gastric emptying and promotion of satiety, thereby reducing the availability of nutrients for absorption and reducing the requirement for insulin secretion. GLP-1 also reduces plasma glucose levels by suppressing glucagon secretion from pancreatic a-cells and potentially by improving insulin sensitivity in peripheral tissues. Further-more, GLP-1 upregulates expression of b-cell genes (GLUT2, glucokinase, insulin, and PDX-1) and promotes b-cell neogenesis and differentiation of ductal cells into insulin secreting cells. Although initial clinical trials indicate GLP-1 has excellent therapeutic potential, its relatively short-lived biological activity and delivery difficulties limit its appeal. Several approaches that are currently being explored to overcome these limitations include mobilizing endogenous GLP-1 release, preserving the biological activity of the native peptide, and developing GLP-1 analogues with extended durations of action.
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Affiliation(s)
- N T Lam
- Departments of Medicine and Physiology, University of Alberta-Edmonton, Alberta, Canada
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Hawryluk RJ, Adler H, Alling P, Ancher C, Anderson H, Anderson JL, Ashcroft D, Barnes CW, Barnes G, Batha S, Bell MG, Bell R, Bitter M, Blanchard W, Bretz NL, Budny R, Bush CE, Camp R, Caorlin M, Cauffman S, Chang Z, Cheng CZ, Collins J, Coward G, Darrow DS, DeLooper J, Duong H, Dudek L, Durst R, Efthimion PC, Ernst D, Fisher R, Fonck RJ, Fredrickson E, Fromm N, Fu GY, Furth HP, Gentile C, Gorelenkov N, Grek B, Grisham LR, Hammett G, Hanson GR, Heidbrink W, Herrmann HW, Hill KW, Hosea J, Hsuan H, Janos A, Jassby DL, Jobes FC, Johnson DW, Johnson LC, Kamperschroer J, Kugel H, Lam NT, LaMarche PH, Loughlin MJ, LeBlanc B, Leonard M, Levinton FM, Machuzak J, Mansfield DK, Martin A. Confinement and heating of a deuterium-tritium plasma. Phys Rev Lett 1994; 72:3530-3533. [PMID: 10056223 DOI: 10.1103/physrevlett.72.3530] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Strachan JD, Adler H, Alling P, Ancher C, Anderson H, Anderson JL, Ashcroft D, Barnes CW, Barnes G, Batha S, Bell MG, Bell R, Bitter M, Blanchard W, Bretz NL, Budny R, Bush CE, Camp R, Caorlin M, Cauffman S, Chang Z, Cheng CZ, Collins J, Coward G, Darrow DS, DeLooper J, Duong H, Dudek L, Durst R, Efthimion PC, Ernst D, Fisher R, Fonck RJ, Fredrickson E, Fromm N, Fu GY, Furth HP, Gentile C, Gorelenkov N, Grek B, Grisham LR, Hammett G, Hanson GR, Hawryluk RJ, Heidbrink W, Herrmann HW, Hill KW, Hosea J, Hsuan H, Janos A, Jassby DL, Jobes FC, Johnson DW, Johnson LC, Kamperschroer J, Kugel H, Lam NT, LaMarche PH, Loughlin MJ, LeBlanc B, Leonard M, Levinton FM, Machuzak J, Mansfield DK. Fusion power production from TFTR plasmas fueled with deuterium and tritium. Phys Rev Lett 1994; 72:3526-3529. [PMID: 10056222 DOI: 10.1103/physrevlett.72.3526] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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