Contextual factors and weight change over time: a comparison between U.S. Hispanics and other population sub-groups.

In recent decades there has been an increasing interest in understanding the role of social and physical contexts in influencing health behaviors and outcomes. This is especially true for weight, which is considered to be highly dependent on environmental factors. The evidence linking neighborhood characteristics to weight in the United States, however, is mixed. Many studies in this area are hampered by cross sectional designs and a limited scope, insofar as they investigate only one dimension of neighborhood context. It is also unclear to what extent neighborhood characteristics account for racial/ethnic disparities in weight. Using longitudinal data from the Los Angeles Family and Neighborhood Survey (L.A. FANS), we compare patterns of weight change between Hispanics and other racial and ethnic groups in order to evaluate whether we observe a pattern of unhealthy assimilation in weight among Hispanic immigrants and to identify differences in the rate at which different groups gain weight over time. We also explore the extent to which patterns of weight change are related to a wider range of community characteristics. We find that weight increases across all groups between the two study waves of L.A. FANS and that the increases are significant except for Asians/Pacific Islanders. With respect to differences in the pace of weight change, second and higher generation Hispanic women and black men gain weight more rapidly than their first generation Hispanic counterparts. Although the evidence presented indicates that first generation Hispanics gain weight, we do not find evidence for convergence in weight since the U.S.-born gain weight at a more rapid rate. The inclusion of community-level variables does not alter the relationships between the race, ethnicity, and immigrant generation categories and weight change. Of the six types of community characteristics considered, only collective efficacy is consistently and significantly associated with weight change, although the protective effect of neighborhood collective efficacy is seen only among women.

The health impacts of international migration on Mexican women.

Mexican migration to the USA is a phenomenon that affects a significant number of Mexican households. In the area of health, considerable research has been devoted to international migrants, but less is known about the health impacts of migration on other household members, particularly the wives of migrants. I used data from the Mexican Migration Project to investigate the health impacts of having a migrant husband. As part of my analysis I explored the relationship between the husbands' migration and several health conditions and behaviours among the wives. In contrast to existing research on the subject, I also considered whether the amount of time the husband spent in the US mediates the relationship between migration and health. Finally, I addressed the possibility that the wives of migrants differ in their initial health endowments from the wives of non-migrants. I found that despite having similar initial health endowments, the wives of migrants have poorer mental health, a higher prevalence of heart disease, and they are more likely to be obese or overweight than the wives of non-migrants.

Healthier before they migrate, less healthy when they return? The health of returned migrants in Mexico.

Over the course of the 20th century, Mexico-U.S. migration has emerged as an important facet of both countries, with far reaching economic and social impacts. The health of Mexican immigrants in the U.S. has been well studied, but relatively less is known about the health of returned migrants to Mexico. The objectives of this paper are twofold. Relying on health data pertaining to two stages of the life course, early life health (pre-migration) and adult health (post-migration) from the Mexican Migration Project gathered between 2007 and 2009, we aim to assess disparities in adult health status between male returned migrants and male non-migrants in Mexico, accounting for their potentially different early life health profiles. While we find evidence that returned migrants had more favorable early life health, the results for adult health are more complex. Returned migrants have a higher prevalence of heart disease, emotional/psychiatric disorders, obesity, and smoking than non-migrants but no differences are found in self-rated health, diabetes, or hypertension.

Socioeconomic differences in obesity among Mexican adolescents.

OBJECTIVE: We investigate socioeconomic disparities in adolescent obesity in Mexico. Three questions are addressed. First, what is the social patterning of obesity among Mexican adolescents? Second, what are the separate and joint associations of maternal and paternal education with adolescent obesity net of household wealth? Third, are there differences in socioeconomic status (SES) gradients among Mexican boys and girls, rural residents and non-rural residents? METHODS: Using data from the Mexican National Health Survey 2000 we examined the slope and direction of the association between SES and adolescent obesity. We also estimated models for sub-populations to examine differences in the social gradients in obesity by sex and non-rural residence. RESULTS: We find that household economic status (asset ownership and housing quality) is positively associated with adolescent obesity. High paternal education is related to lower obesity risk, whereas the association between maternal education and obesity is positive, but not always significant. CONCLUSION: The household wealth components of SES appear to predispose Mexican adolescents to higher obesity risk. The effects of parental education are more complex. These findings have important policy implications in Mexico and the United States.

The role of androgens in development of the scrotum of the grey short-tailed Brazilian opossum ( Monodelphis domestica).

In eutherian mammals, sex differentiation is initiated by expression of the testis-determining gene on the Y chromosome. Subsequent phenotypic development of the reproductive tract and genitalia depends on the production of hormones by the differentiated testis. In marsupials the mechanisms of phenotypic development may vary from this pattern, as differentiation of the scrotal primordia has been shown to occur before that of the gonad. Thus, the development of the scrotum in the marsupial has been regarded as an androgen-independent process. We have sought to clarify the ontogeny of scrotal development and the appearance of androgen receptor immunoreactivity by examining Monodelphis domesticaembryos/pups from 1 day prior to birth until 2 days after birth. We have also used immunocytochemistry to determine the expression of the key steroidogenic enzyme 3beta-hydroxysteroid dehydrogenase as an indicator of when the developing gonad may be capable of synthesizing androgens. Expression of this enzyme was first detected in the gonads and adrenals of both sexes 1 day prior to birth and before the appearance of scrotal bulges. Androgen receptor immunoreactivity was detected in the scrotal anlagen of male opossum pups as early as 1 day following birth. This finding is significantly earlier than previous reports and coincides with the appearance 1 day after birth of distinct scrotal bulges. Androgen receptor immunoreactivity was also observed in the genital tubercles of male pups, but not female pups, 2 days after birth. These results suggest that androgens may play an important role in the development of the male genitalia at a much earlier stage than that indicated by previously published work and that scrotal development in this species may not be androgen-independent.