Rates of [1-¹³C]oxidation in guatemalan children with chronic immunostimulation

It has been s-uggested that chronic immunostimulation, such as occurs in highly contaminated environments, causes a persistent catabolic state, shifting indispensable amino acids toward the synthesis of acute-phase proteins, at the expense of growth. To evaluate this hypothesis, we studied 9 children, aged 3 to 5 y, living in a highly contaminated area (garbage dump of Guatemala City) and who manifested elevations of the cytokine biomarkers (TNFa and/or ILi) A modified approach, to simplify the procedures and develop a protocol for use in young children, and at the community-level was explored, including: 1) the oral (po) administration of isotopes; 2) enrichment of ¹³CO₂ in expired air and a -kctoisocaproic acid (KIC) in plasma for calculations of Leu-oxidation rates; and 3) a total elapsed procedure time of <8 h. 180 min after a po priming-dose of ¹³CO₂-bicarbonate, po challenge-doses of ¹³CO₂-Leu are given every 20 min over an additional 4.5 h. Subjects remain in the fed-state, receiving 75% of recommended daily energy, in divided servings every 20 min. After initiating the challenge doses, isotopic enrichment of expired air is measured every 20 min from 200-280 min. Blood samples were collected at 240, 260, and 280 min. ¹³CO₂ enrichments reached 0.045 - 0.050 APE by 120 min in all cases. Calculated Leu-oxidanon rates ranged from 26.6 - 74,1 umol/kg/h. We conclude that a simplified field approach to measurement of leucine oxidation is at hand.