Mayores concentraciones de cortisol, biomarcador de estrés, en residentes de comunas con menor índice de calidad de vida urbana / Higher levels of cortisol, a biomarker of stress, among residents of municipalities with lower urban life quality index

INTRODUCCIÓN: Las desigualdades socioeconómicas y territoriales se relacionan con la salud de la población santiaguina; sin embargo, los mecanismos causales que generan las inequidades en salud no están del todo claros. En este trabajo, se cuantifica el estrés de individuos viviendo en diferentes comunas, y se lo discute como causa y consecuencia de procesos vinculados con inequidades en salud. EL OBJETIVO era relacionar el Índice de Calidad de Vida Urbana (ICVU) de la comuna de residencia de individuos en Santiago de Chile con las concentraciones de cortisol en pelo (CCP), un biomarcador de los niveles de estrés fisiológico crónico. MATERIALES Y MÉTODOS: Se exploró la relación entre CCP y la edad, el sexo y el ICVU de la comuna de residencia en 80 estudiantes de educación superior en Santiago de Chile. RESULTADOS: No se encontraron correlaciones significativas entre CCP y la edad o el sexo de los participantes. Se encontró una correlación significativa entre CCP y los valores del ICVU de la comuna de residencia, además de encontrar diferencias significativas entre CCP y los distintos rangos de ICVU (Superior, Promedio e Inferior).DISCUSIÓN: Los resultados sugieren considerar las diferencias individuales de CCP como resultado de desigualdades socio-territoriales y también como posible causa de inequidades en salud. Se recomienda incluir el rol del estrés en las políticas públicas de salud, ampliando las redes de apoyo y prevención de estrés en los sectores con bajo ICVU.

INTRODUCTION: Socioeconomic and urban inequalities are associated with health in Santiago; nonetheless, the causal mechanisms underlying health inequalities are not entirely clear. This article quantifies the stress of individuals living in different municipalities and discusses its role as cause and consequence in the generation of health inequalities. THE OBJECTIVE of this study was to determine the relationship between the Urban Quality of Life Index (UQoLI) of individuals' municipality of residence in Santiago, Chile with their hair cortisol concentrations (HCC), a biomarker of chronic physiological stress.MATERIALS AND METHODS: The relationship of HCC with age, sex and UQoLI was explored in a sample of 80 university students in Santiago, Chile. RESULTS: No significant correlations were found between HCC and age and sex. A significant correlation was found between HCC and UQoLI, and significant differences were found be-tween HCC at different levels of UQoLI (High, Average, and Low).DISCUSSION: Results suggest that HCC differences could be considered a result of urban in-equalities, as well as a possible cause of health inequalities. The role of stress should be inclu-ded in public health policies, to expand support networks and prevent stress, especially among people living in areas with low urban quality of life.

Interplay between thermal and immune ecology: effect of environmental temperature on insect immune response and energetic costs after an immune challenge.

Although the study of thermoregulation in insects has shown that infected animals tend to prefer higher temperatures than healthy individuals, the immune response and energetic consequences of this preference remain unknown. We examined the effect of environmental temperature and the energetic costs associated to the activation of the immune response of Tenebrio molitor larvae following a lipopolysaccharide (LPS) challenge. We measured the effect of temperature on immune parameters including phenoloxidase (PO) activity and antibacterial responses. Further as proximal and distal costs of the immune response we determined the standard metabolic rate (SMR) and the loss of body mass (m(b)), respectively. Immune response was stronger at 30°C than was at 10 or 20°C. While SMR at 10 and 20°C did not differ between immune treatments, at 30°C SMR of LPS-treated larvae was almost 25-60% higher than SMR of PBS-treated and naïve larvae. In addition, the loss in m(b) was 1.9 and 4.2 times higher in LPS-treated larvae than in PBS-treated and naïve controls. The immune responses exhibited a positive correlation with temperature and both, SMR and m(b) change, were sensitive to environmental temperature. These data suggest a significant effect of environmental temperature on the immune response and on the energetic costs of immunity.

Energetic costs of detoxification systems in herbivores feeding on chemically defended host plants: a correlational study in the grain aphid, Sitobion avenae.

Herbivorous insects have developed mechanisms to cope with plant barriers, including enzymatic systems to detoxify plant allelochemicals. Detoxification systems may be induced when insects are feeding on plants with increasing levels of allelochemicals. Increases in enzymatic activity have been related to energetic costs, and therefore less energy may be allocated to fitness-related traits. In this study, we explored the induction and energetic costs of detoxifying hydroxamic acids (Hx; a wheat allelochemical) in the grain aphid, Sitobion avenae. Aphids were reared on three wheat cultivars with different levels of Hx (0.26+/-0.08, 2.09+/-0.6 and 5.91+/-1.18 mmol kg(-1) fresh mass). We performed a nested ANOVA to test the effect of Hx (main factor) and intrahost variation (nested factor) on body mass, standard metabolic rate (SMR) and the enzymatic activity of cytochrome P450s monooxygenases (P450s), glutathione S-transferases (GSTs) and esterases (ESTs). We found non-significant effects of Hx levels (P>0.5 for all tests), but there was significant intrahost variation (P<0.05 for all tests). In addition, we found a negative correlation between SMR and ESTs (P=0.003) and no correlation between SMR and GSTs or P450s (P=n.s after a Bonferroni correction). Multiple regression between SMR (dependent variable) and enzymatic activities (predictor variables) was significant (P=0.007), but detoxification enzymes only explained about 5% of the variation of SMR. Finally, we found a non-significant path coefficient between ;metabolism' and ;detoxifying capacity' (P>0.05). These results suggest that increased enzymatic activities do not entail increased metabolic rate. Therefore, low energetic costs in aphids would facilitate the use of different hosts and promote a wider ecological niche.