RESUMO
BACKGROUND: A series of antioxidant enzymes and non-enzymatic compounds act to protect cells from uncontrolled propagation of free radicals. It is poorly understood, though, to what extent and how their interaction is harmonized. OBJECTIVES: To explore associative interactions among a battery of urinary and blood biomarkers of oxidative stress and enzymatic and non-enzymatic markers of the antioxidant defense system in children from low income households. METHODS: For this cross-sectional descriptive study, urine, red cells, and plasma were sampled in 82 preschool children attending three daycare centers in Quetzaltenango Guatemala. The urinary oxidative stress biomarkers studied were F2-isoprostanes and 8-hydroxy-deoxy-guanosine. Red cell enzyme activities measured were: catalase, superoxide dismutase, glutathione peroxidase and glutathione reductase. Circulating non-enzymatic antioxidants selected were: retinol, tocopherols, ß-carotene and coenzymes Q9 and Q10. RESULTS: In a Spearman rank-order correlation hemi-matrix, of 55 paired combinations of the 11 biomarkers, 28 (51%) were significantly correlated among each other (p ≤ 0.05), with the strongest association being retinol and tocopherols (r = 0.697, p<0.001), and 4 associations (9%) showed a trend (p> 0.5 to ≤ 0.10). F2-isoprostanes showed the greatest number of cross-associations, having significant interactions with 8 of the 10 remaining biomarkers. Goodness-of-fit modeling improved or maintained the r value for 24 of the significant interactions and for one of the 5 borderline associations. Multiple regression backward stepwise analysis indicated that plasma retinol, ß-carotene and coenzyme Q10 were independent predictors of urinary F2-isoprostanes. CONCLUSION: Numerous significant associations resulted among biomarkers of oxidation and responders to oxidation. Interesting findings were the apparent patterns of harmonious interactions among the elements of the oxidation-antioxidation systems in this population.
Assuntos
Antioxidantes/metabolismo , Nucleotídeos de Desoxiguanina , F2-Isoprostanos , Estresse Oxidativo , Oxirredutases/sangue , 8-Hidroxi-2'-Desoxiguanosina , Biomarcadores/sangue , Biomarcadores/urina , Criança , Pré-Escolar , Estudos Transversais , Nucleotídeos de Desoxiguanina/sangue , Nucleotídeos de Desoxiguanina/urina , F2-Isoprostanos/sangue , F2-Isoprostanos/urina , Feminino , Guatemala , Humanos , Masculino , Fatores SocioeconômicosRESUMO
BACKGROUND: Guatemala is a country with the highest prevalence of stunting in under-5 children in the Americas, with a national average of 49.8%. Asymptomatic intestinal colonization with Giardia intestinalis is common in Guatemalan preschoolers and has been implicated as a factor in linear growth retardation. The potential mechanisms of any giardiasis-growth interaction have not been exhaustively explored. OBJECTIVES: The aim of the present study was to describe urine oxidative stress biomarkers and erythrocyte antioxidant enzyme activity, and to explore any association with prevalence or intensity of G intestinalis infection in preschoolers attending 3 government-subsidized day care centers in the Guatemalan Western Highlands. METHODS: Samples of feces, urine, and red blood cell (RBC) hemolysate were collected in a total of 74 preschoolers enrolled in 3 day care centers. Giardia prevalence and a proxy index for intensity were assessed by enzyme-linked immunosorbent assay (ELISA). Urinary biomarkers of oxidative damage to DNA (8-hydroxydeoxyguanosine [8-OHdG]) and to lipid (F2t 15-Isoprostane [F2-Iso]) were measured by ELISA. The erythrocyte activity of catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GSR), and glutathione peroxidase (GPX) were measured by respective spectroscopic substrate-based reaction assays. RESULTS: Median values of RBC CAT activity (Pâ=â0.016) and urine F2-Iso (Pâ=â0.023) differed between children who were positive (nâ=â39) and negative (nâ=â35) for Giardia. Similarly, G intestinalis intensity was significantly and positively associated with urinary F2-Iso (râ=â0.446, Pâ<â0.001), RBC SOD (râ=â283, Pâ=â0.014), and RBC CAT (râ=â0.260, Pâ=â0.025). CONCLUSION: The optical density reading of the fecal ELISA assay for G intestinalis has potential as a proxy for the intensity of infestation. In this respect, there exists an association of this intensity with indicators of the systemic oxidation.