RESUMO
BACKGROUND: Both tissue hypoxia in vitro, and whole-body hypoxia in vivo, have been found to promote the release of reactive oxygen species (ROS) that are potentially damaging to the cardiovascular system. Antioxidant systems protect against oxidative damage by ROS and may exhibit some degree of responsiveness to oxidative stimuli. Production of urate, a potent soluble antioxidant, is increased in hypoxic conditions. We aimed to determine whether urate is an important antioxidant defense in healthy subjects exposed to hypoxia. METHODS: We conducted a cohort study of 25 healthy lowland volunteers during acute exposure to high altitude (4 days at 3,600 m, followed by 10 days at 5,200 m) on the Apex high-altitude research expedition to Bolivia. We measured markers of oxidative stress (8-isoprostane F2), serum urate concentration, and total plasma antioxidant activity by two techniques: 2,2'-amino-di-[3-ethylbenzthiazole sulfonate] spectrophotometry (total antioxidant status [TAS]) and enhanced chemiluminescence (ECL). RESULTS: On ascent, F2-isoprostane levels were significantly elevated compared with those at sea level (p < 0.01). After 1 week at high altitude, plasma antioxidant capacity (AOC) by both TAS and ECL, and serum urate concentration were significantly elevated (each p < 0.01 vs sea level), and F2-isoprostane levels were reduced to values at sea level. There was a highly significant correlation between plasma urate and AOC at this stage (ECL, r(2) = 0.59, p = 0.0001; TAS, r(2) = 0.30, p = 0.0062). CONCLUSIONS: Our results support the hypothesis that urate may act as a responsive endogenous antioxidant in high-altitude hypoxia.
Assuntos
Altitude , Antioxidantes/metabolismo , Hipóxia/metabolismo , Hipóxia/fisiopatologia , Ácido Úrico/sangue , Adulto , Antioxidantes/fisiologia , Bolívia , Estudos de Coortes , F2-Isoprostanos/sangue , Feminino , Humanos , Medições Luminescentes , Masculino , Estresse Oxidativo/fisiologia , Espécies Reativas de Oxigênio/metabolismo , Ácido Úrico/metabolismoAssuntos
Líquido Amniótico/fisiologia , Complexo Antígeno-Anticorpo/metabolismo , Glomerulonefrite/metabolismo , Doenças do Complexo Imune/metabolismo , Glomérulos Renais/patologia , Animais , Feminino , Mesângio Glomerular/patologia , Glomerulonefrite/imunologia , Glomerulonefrite/patologia , Doenças do Complexo Imune/patologia , Camundongos , Camundongos Endogâmicos , Sistema Fagocitário Mononuclear/fisiologia , Gravidez , alfa-Fetoproteínas/fisiologiaAssuntos
Coagulação Intravascular Disseminada/sangue , Fibronectinas/sangue , Animais , Coagulação Intravascular Disseminada/induzido quimicamente , Coagulação Intravascular Disseminada/patologia , Imunoeletroforese , Rim/ultraestrutura , Pulmão/ultraestrutura , Masculino , Polianetolsulfonato , RatosRESUMO
PIP: This study, based on interviews with Mexican documented and undocumented women workers in Los Angeles county, finds that most of the women in both categories work in factories. Contrary to popular impression, only 10% of the undocumented women in this survey are engaged in private household employment, although 19% were so employed when they 1st came to the US. Despite this obvious change in occupation, in general occupational mobility from 1st jobs is insignificant. On the average, undocumented women's hourly rate of pay was 40 US cents higher than the minimum wage, and US$1.57 lower than the average documented women's wages. Within the same occupational category, the undocumented women earned less per hour. The smallest difference occured in the 'laborer's' category. Another departure from popular impression was that, 76% of undocumented workers were paid by check. The figure was 94% for documented women workers. The respondents who said they were paid in cash were most likely to be in the private household sector. 80% of the undocumented workers did not think that they were discriminated against in their jobs, suggesting that they are a rather timid group of workers who believe that they have no real options regarding their work life, and are relatively satisfied with what they have. Almost all the women said that they came to the US with the intention of staying permanently, or as long as they are not caught and sent back to Mexico, which is their biggest fear. Better job and better pay are the most important reasons given by most women for coming. Being temporarily laid off would not prompt them to return to Mexico, as they are confident that their chances of finding another minimum wage paying job are better in the US. A closek knit network of support usually tides them over during their period of joblessness.^ieng