The purpose of this study was to investigate differences in substrate oxidation between dextrose (DEX) and unmodified (UAMS) and acid/alcohol-modified (MAMS) cornstarches. Seven endurance-trained men (VO2peak = 59.1 ± 5.4 mL·kg−1·min−1) participated in 2 h of exercise (66.4% ± 3.3% VO2peak) 30 min after ingesting 1 g/kg body weight of the experimental carbohydrate or placebo (PLA). Plasma glucose and insulin were elevated after DEX (P < 0.05) compared with UAMS, MAMS, and PLA. Although MAMS and DEX raised carbohydrate oxidation rate through 90 min of exercise, only MAMS persisted throughout 120 min (P < 0.05 compared with all trials). Exogenous-carbohydrate oxidation rate was higher in DEX than in MAMS and UAMS until 90 min of exercise. Acid/alcohol modification resulted in augmented carbohydrate oxidation with a small, sustained increase in exogenous-carbohydrate oxidation rate. MAMS appears to be metabolizable and available for oxidation during exercise.
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Neil M. Johannsen and Rick L. Sharp
Alejandro M. Rosales, Nathan A. Keck, Tim C. Shriver, Dale A. Schoeller, and Brent C. Ruby
filter to remove particulate and organic matter. Deuterium analysis was completed by reducing a 0.8 μl aliquot of cleaned urine samples over chromium at 850°C via Finnigan MAT H/Device. Resultant hydrogen was analyzed via a dual-inlet system on a Thermo Delta Plus isotope ratio mass spectrometer (San Jose
Francesco Campa, Catarina N. Matias, Elisabetta Marini, Steven B. Heymsfield, Stefania Toselli, Luís B. Sardinha, and Analiza M. Silva
was given an oral dose of 0.1 g of 99.9%. H 2 O per kg of body weight (Sigma-Aldrich, St. Louis, MO) for the determination of TBW by deuterium dilution using a Hydra stable isotope ratio mass spectrometer (PDZ Europa; Europa Scientific, Cheshire, United Kingdom). Subjects were encouraged to void their
Hiroyuki Sagayama, Makiko Toguchi, Jun Yasukata, Kazunari Yonaha, Yasuki Higaki, and Hiroaki Tanaka
, incorporating a special silicone gasket for the best possible seal, and were wrapped tightly with Parafilm M (Bemis Co., Inc., Oshkosh, WI). We analyzed the urine samples with isotope ratio mass spectrometry (Hydra 20-20 Stable Isotope Mass Spectrometer; SerCon Ltd., Crewe, United Kingdom). The 18 O and 2 H
David R. Paul, Ryan McGrath, Chantal A. Vella, Matthew Kramer, David J. Baer, and Alanna J. Moshfegh
H 2 O per kilogram and 0.08 g of H 2 18 O per kilogram of body weight. 29 A 24-hour urine sample collected on the previous day was used to measure background isotope enrichments. Isotopic enrichment of urine samples was measured using continuous-flow isotope-ratio mass spectroscopy (Europa
Rachel B. Parks, Hector F. Angus, Douglas S. King, and Rick L. Sharp
, it can be partially hydrolyzed with hydrochloric acid and alcohol, producing modified amylomaize-7, which is 92% digestible and readily soluble in water ( Zhou & Kaplan, 1997 ). Johannsen and Sharp ( 2007 ) used 13 C isotope-ratio analysis to demonstrate that modified amylomaize-7 starch is
Megan Colletto and Nancy Rodriguez
isotope ratio mass spectroscopy (IRMS) by a commercial laboratory (Metabolic Solutions, Nashua NH) and corrected for background enrichment. Total urinary nitrogen was determined using the micro-Kjeldahl method (Tecator Kjeltec System, Hoganus, Sweden) for estimation of nitrogen excretion (NE). Nitrogen
Ioanna Athanasiadou, Sven Christian Voss, Wesal El Saftawy, Hind Al-Jaber, Najib Dbes, Sameera Al-Yazedi, Waseem Samsam, Vidya Mohamed-Ali, Mohammed Alsayrafi, Georgia Valsami, and Costas Georgakopoulos
ratio of testosterone/epitestosterone, the biomarker that triggers gas chromatography–combustion–isotope ratio mass spectrometry (GC–C–IRMS) analysis for the detection of exogenous anabolic steroid abuse ( Goebel et al., 2009 ). Therefore, LH is included in the World Anti-Doping Agency (WADA) Prohibited
Victoria C. Edwards, Stephen D. Myers, Sophie L. Wardle, Andrew G. Siddall, Steven D. Powell, Sarah Needham-Beck, Sarah S. Kefyalew, Priya A. Singh, Elise R. Orford, Michelle C. Venables, Sarah Jackson, Julie P. Greeves, and Sam D. Blacker
were frozen at −20°C until later analysis using isotope ratio mass spectrometry. The rate of CO 2 production was determined using the multipoint method of Schoeller et al. ( 1986 ) and converted to EE using the energy equivalent of CO 2 ( Elia & Livesey, 1988 ), assuming a respiratory quotient of 0
