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1.
Pediatrics ; 120(6): e1426-33, 2007 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-18055661

RESUMO

OBJECTIVE: The objective of this study was to examine the major constituent of nonesterified fatty acids in children with respect to auxologic parameters, insulin sensitivity, and lipid levels, because nonesterified fatty acid levels are elevated in obesity and are important in the development of comorbidities. METHODS: Fasting blood samples were obtained from 73 children (43 girls; 49 obese; median [range] age: 11.4 [0.9-17.6] years). Concentrations of the major circulating nonesterified fatty acids (myristate, palmitate, oleate, stearate, and arachidate) were determined by gas chromatography mass spectrometry, alongside measurement of insulin, adiponectin, and lipid profiles. RESULTS: The sum of all nonesterified fatty acids was significantly higher in obese versus normal-weight children, although gender (but not age or puberty) was an important determinant, with the difference remaining significant only in boys. Overall, obese children had higher concentrations of myristate, palmitate, and oleate but not stearate or arachidate. Age was an important determinant of myristate and arachidate, whereas gender proved more important for palmitate and stearate. Fasting insulin concentrations were not associated with either total nonesterified fatty acid concentrations or any of the individual nonesterified fatty acids, although a positive correlation was found between adiponectin and total nonesterified fatty acid concentrations that was independent of obesity status and that seemed mediated by changes in palmitate and stearate. Serum total cholesterol and low-density lipoprotein (but not high-density lipoprotein) levels seemed to correlate positively with circulating concentrations of palmitate, oleate, and stearate, whereas serum triacylglycerols correlated with myristate, palmitate, and oleate concentrations. CONCLUSIONS: Nonesterified fatty acid concentrations are elevated in obese children, primarily as a result of increases in myristate, palmitate, and oleate. Independent effects of nonesterified fatty acids on circulating adiponectin levels and lipid parameters were observed, although we found no relationship between nonesterified fatty acid concentrations and the insulin resistance identified with obesity.


Assuntos
Adiposidade , Colesterol/sangue , Jejum/sangue , Ácidos Graxos não Esterificados/sangue , Resistência à Insulina , Lipoproteínas/sangue , Obesidade/sangue , Triglicerídeos/sangue , Adolescente , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Masculino
2.
Med Sci Sports Exerc ; 39(9): 1579-86, 2007 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-17805091

RESUMO

PURPOSE: It has been suggested that exercise-induced changes in plasma volume (PV) confound the interpretation of biochemical data obtained during the recovery period from exercise. No studies have sought to assess the effect of short-duration, high-intensity exercise on PV change and plasma lipid and lipoprotein concentrations. The purpose of this study was to compare power profiles, changes in PV, and plasma lipid and lipoprotein concentrations immediately after and 24 h after exercise. METHODS: Subjects undertook two 30-s, high-intensity cycle ergometer protocols after optimization of resistive loads calculated from total body mass (TBM) and fat-free mass (FFM). Power output indices were recorded and blood samples were analyzed before, immediately after, and 24 h after exercise. RESULTS: Peak power outputs were significantly greater in FFM (1020+/-134 vs 953+/-114 W for FFM and TBM, respectively, P<0.05). No differences were found between TBM and FFM for mean power output, fatigue index, or work done. Significant decreases (P<0.05) in PV of 12.0+/-5.7 and 12.3+/-6.7% were recorded immediately after exercise for both TBM and FFM, respectively. At 24 h after exercise, a significant (P<0.05) increase in PV of 4.2+/-10.3% was recorded for TBM only. Significant increases (P<0.01) were recorded for serum triglyceride, cholesterol, HDL cholesterol, and LDL cholesterol immediately after exercise for both TBM and FFM. These increases disappeared when corrected for PV changes, with the exception of LDL cholesterol in TBM, which still displayed a significant increase compared with the preexercise values (2.50+/-0.74 mM (before) vs 2.72+/-0.84 mM (immediately after)). CONCLUSIONS: Our data show that short-duration, high-intensity cycle ergometer exercise tests can induce significant plasma volume decreases in untrained subjects, which may affect the interpretation of bloodborne biochemical parameters.


Assuntos
Ciclismo/fisiologia , Ergometria/métodos , Lipídeos/análise , Lipoproteínas/análise , Esforço Físico/fisiologia , Volume Plasmático/fisiologia , Adulto , Humanos , Masculino
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