title: Oxidative damage to proteins related to metals and antioxidant defenses in breastmilk.
abstract: BACKGROUND
  Breast milk contains molecules needed for the development of children; the integrity and function of these molecules is affected by the presence of pro-oxidants. Protein carbonyls are mainly produced as a result of the interaction of metals with reactive oxygen species (ROS), which may initiate a chain reaction that promotes molecular oxidation.
  
  
  OBJECTIVE
  This study aimed to determine the association between the concentration of protein carbonyls with the concentration of trace elements (lead [Pb], cadmium [Cd] and selenium [Se]), superoxide radical (O2•-) production, and glutathione (GSH) content, as well with the activity of the main antioxidant enzymes (superoxide dismutase [SOD], catalase [CAT], glutathione peroxidase [GPx], glutathione reductase [GR] and glutathione S-transferase [GST]) in breast milk.
  
  
  METHODS
  In this study 108 transitional milk samples (7-10 days) were analyzed. Antioxidant enzyme activities, O2•-production, protein carbonyl and GSH concentrations were analyzed by spectrophotometry. Trace element concentration was quantified by atomic absorption spectrophotometry. Generalized linear modelling was used to assess the relationship between protein carbonyls concentration with oxidative stress indicators and trace elements concentration.
  
  
  RESULTS
  Cd and Pb were detected in 21.3 and 55.6% of breast milk samples, respectively. The median concentration of Cd was 0.01 µg L-1 (0.01-3.52 µg L-1) and Pb concentration was 2.61 µg L-1 (0.08-195.20 µg L-1). According to the best-fit model, the main factors contributing to protein carbonyl concentrations were the activity of GPx, GR, and concentration of GSH, Se, Pb and Cd.
  
  
  CONCLUSIONS
  According to the generalized linear model, the activity of GPx and GR, could help explain protein oxidation induced by Pb and Cd in breast milk.
authors.affiliation: Centro de Investigaciones Biológicas del Noroeste S.C. Instituto Politécnico Nacional 195. La Paz, Baja California Sur. México. r.gaxiolar@gmail.com.
authors.forename: Patricia Carolina
authors.initials: PC
authors.lastname: Castillo-Castañeda
authors.forename: Ramón
authors.initials: R
authors.lastname: Gaxiola-Robles
authors.forename: Vanessa
authors.initials: V
authors.lastname: Labrada-Martagón
authors.forename: Baudilio
authors.initials: B
authors.lastname: Acosta Vargas
authors.forename: Lía Celina
authors.initials: LC
authors.lastname: Méndez-Rodríguez
authors.forename: Tania
authors.initials: T
authors.lastname: Zenteno-Savín
mesh_terms: D000328:Adult; D000975:Antioxidants / Q000032:analysis*; D005260:Female; D005979:Glutathione Peroxidase / Q000737:chemistry; D005980:Glutathione Reductase / Q000737:chemistry; D006801:Humans; D008670:Metals / Q000009:adverse effects / Q000737:chemistry*; D019216:Metals, Heavy / Q000009:adverse effects / Q000737:chemistry; D008894:Milk Proteins / Q000737:chemistry*; D008895:Milk, Human / Q000737:chemistry*; D010084:Oxidation-Reduction; D050050:Protein Carbonylation / Q000187:drug effects
chemical_list: D000975:Antioxidants; D008670:Metals; D019216:Metals, Heavy; D008894:Milk Proteins; D005979:Glutathione Peroxidase; D005980:Glutathione Reductase
keywords: Antioxidants.  Breast milk. Protein  carbonyls. Trace  elements.