Noninvasive markers of oxidative DNA stress, RNA degradation and protein degradation are differentially correlated with resting metabolic rate and energy intake in children and adolescents

Abstract

Urinary excreted RNA and DNA catabolites are used as noninvasive markers for metabolic processes: 8-oxo-2′-deoxyguanosine (8-oxodG) potentially represents oxidative stress to DNA/deoxyribonucleotidetriphosphate pool, modified ribonucleoside pseudouridine (ψ) originating mainly from degraded rRNA and tRNA reflects RNA turnover. Modified amino acid γ-carboxyglutamic acid (Gla) stems from degraded proteins reflecting turnover of proteins. Aim of the present study was to investigate (44 healthy males, 3-18 y) how excretion rates of 8-oxodG, ψ, and Gla are related to resting metabolic rate and energy intake. Excretion rates of 8-oxodG (pmol/kg/d), ψ (μmol/kg/d), and Gla (μmol/kg/d) were significantly correlated with resting metabolic rate (kJ/kg/d): r = 0.108 (p = 0.029), 0.691 and 0.552 (p < 0.0001), respectively. Excretion rates of 8-oxodG, ψ, and Gla were also significantly correlated with energy intake (kJ/kg/d): r = 0.108 (p = 0.036), 0.602 and 0.462 (p < 0.0001). 8-oxodG and Gla excretion was significantly correlated with ψ excretion: r = 0.174 (p = 0.005) and 0.709 (p < 0.0001). These results indicate close relationships between whole-body RNA and protein degradation and metabolic rate. The relationship between 8-oxodG excretion and metabolic rate, however, is less strong suggesting that factors other than metabolic rate considerably affect the oxidative stress to DNA. © 2008 International Pediatric Research Foundation, Inc.