Nalini Ranjit

Vulnerability to heat-related mortality in Latin America: a case-crossover study in São Paulo, Brazil, Santiago, Chile and Mexico City, Mexico

BACKGROUND Factors affecting vulnerability to heat-related mortality are not well understood. Identifying susceptible populations is of particular importance given anticipated rising temperatures from climatic change. METHODS We investigated heat-related mortality for three Latin American cities (Mexico City, Mexico; São Paulo, Brazil; Santiago, Chile) using a case-crossover approach for 754 291 deaths from 1998 to 2002. We considered lagged exposures, confounding by air pollution, cause of death and susceptibilities by educational attainment, age and sex. RESULTS Same and previous day apparent temperature were most strongly associated with mortality risk. Effect estimates remained positive though lowered after adjustment for ozone or PM(10). Susceptibility increased with age in all cities. The increase in mortality risk for those >or=65 comparing the 95th and 75th percentiles of same-day apparent temperature was 2.69% (95% CI: -2.06 to 7.88%) for Santiago, 6.51% (95% CI: 3.57-9.52%) for São Paulo and 3.22% (95% CI: 0.93-5.57%) for Mexico City. Patterns of vulnerability by education and sex differed across communities. Effect estimates were higher for women than men in Mexico City, and higher for men elsewhere, although results by sex were not appreciably different for any city. In São Paulo, those with less education were more susceptible, whereas no distinct patterns by education were observed in the other cities. CONCLUSIONS Elevated temperatures are associated with mortality risk in these Latin American cities, with the strongest associations in São Paulo, the hottest city. The elderly are an important population for targeted prevention measures, but vulnerability by sex and education differed by city.

Race/ethnicity and telomere length in the Multi-Ethnic Study of Atherosclerosis

Telomere length has emerged as a marker of exposure to oxidative stress and aging. Race/ethnic differences in telomere length have been infrequently investigated. Leukocyte telomere length (LTL) was assessed 981 white, black and Hispanic men and women aged 45–84 years participating in the Multi‐Ethnic Study of Atherosclerosis. Direct measurement and questionnaire were used to assess covariates. Linear regression was used to estimate associations of LTL with race/ethnicity and age after adjustment for sex, income, education, smoking, physical activity, diet and body mass index. On average blacks and Hispanics had shorter telomeres than whites [adjusted mean differences (standard error) in T/S ratio compared to whites: −0.041 (0.018) for blacks and −0.044 (0.018) for Hispanics]. Blacks and Hispanics showed greater differences in telomere length associated with age than whites (adjusted mean differences in T/S ratio per 1 year increase in age −0.0018, −0.0047 and −0.0055 in whites, blacks and Hispanics respectively). Differences in age associations were more pronounced and only statistically significant in women. Race/ethnic differences in LTL may reflect the cumulative burden of differential exposure to oxidative stress (and its predictors) over the lifecourse.

Socioeconomic and race/ethnic differences in daily salivary cortisol profiles: The Multi-Ethnic Study of Atherosclerosis

It has often been hypothesized that stress and its biological consequences mediate the relationship between low socioeconomic status (SES) or minority status and poor cardiovascular disease outcomes. The objective of this study was to determine if daily cortisol patterns, a biomarker of the stress response, differ by race/ethnicity and socioeconomic status. Data were collected from 935 Black, White and Hispanic adults age 48-90 years old. Salivary cortisol samples were collected six times per day over 3 days: at awakening, 30min later, at 1000h, noon, 1800h and at bedtime. Blacks and Hispanics had lower levels of wake-up cortisol and less steep early declines, while Blacks had flatter and Hispanics steeper late day declines relative to Whites. Similarly the low socioeconomic status group also had lower levels of wake-up cortisol and less steep decline during the early part of the day. These patterns remained after adjustment for health behaviors and psychosocial factors. This study finds an association between salivary cortisol and race/ethnicity and SES in a multi-ethnic study population. Further work is needed to determine the health consequences of these differences.

Socioeconomic Position, Race/Ethnicity, and Inflammation in the Multi-Ethnic Study of Atherosclerosis

Background— Low socioeconomic position is known to be associated with cardiovascular events and atherosclerosis. Reasons for these associations remain a topic of research. Inflammation could be an important mediating mechanism linking socioeconomic position to cardiovascular risk. Methods and Results— This cross-sectional study used data from the baseline examination of the Multi-Ethnic Study of Atherosclerosis (MESA), a study of 6814 men and women 45 to 84 years of age. Race- and ethnicity-stratified regression analyses were used to estimate associations of household income and education with C-reactive protein and interleukin-6 before and after adjustment for infection and medication use, psychosocial factors, behaviors, adiposity, and diabetes mellitus. Low income was associated with higher concentrations of interleukin-6 in all race/ethnic groups. Percent differences associated with 1-SD–lower income were 9% (95% confidence interval [CI], 7 to 11), 6% (95% CI, 1 to 10), 8% (95% CI, 4 to 11), and 8% (95% CI, 3 to 13) for whites, Chinese, blacks, and Hispanics. Low levels of education were associated with higher levels of interleukin-6 only among whites and blacks (percent difference in interleukin-6 associated with 1-SD–lower education: 9% [95% CI, 6 to 12] among Whites, and 7% [95% CI, 3 to 10] among blacks). Similar patterns were observed for C-reactive protein. Adiposity was the single most important factor explaining socioeconomic position associations, especially among blacks and whites. A smaller effect was seen for psychosocial factors and behaviors in all race groups. Conclusions— Both household income and education are associated with inflammation, but associations vary across race/ethnic groups. Associations likely result from socioeconomic position patterning of adiposity and other factors.

Reductions in Child Obesity Among Disadvantaged School Children With Community Involvement: The Travis County CATCH Trial

The objective of this study was to compare the impact of two intervention approaches on the prevalence of child overweight and obesity: (i) Coordinated Approach To Child Health BasicPlus (CATCH BP), in which schools were provided evidence‐based coordinated school health program training, materials, and facilitator support visits, and (ii) CATCH BP and Community (BPC), in which BP schools received additional promotion of community partnerships with the aim of integrating community members and organizations into schools, local decision making and action, and best practices workshops. Schools (n = 97) in four central Texas districts were recruited to participate in the 4‐year project. Of the low‐income schools (n = 58), 15 schools were selected to receive the BPC intervention and matched with 15 schools in the BP condition. A serial cross‐sectional design was used, in which 4th grade student BMI, physical activity, and diet were assessed in the 30 schools in spring 2007 and 2008. Measurements in spring 2007 included 1,107 students, with 53% female; 61% Hispanic, and 14% African American; and mean age of 9.9 years. Adjusted prevalence of overweight/obesity (≥85th percentile) was 42.0 and 47.4% in spring 2007 for the BP and BPC students, respectively. From spring 2007 to spring 2008, the percent of students classified as overweight/obese decreased by 1.3 percentage points (P = 0.33) in BP schools, compared to a decrease of 8.3 percentage points (P < 0.005) in students from BPC schools; the difference between conditions was significant (P = 0.05). CATCH BPC students also reported more positive trends in related behaviors. Implementation of a community‐enhanced school program can be effective in reducing the prevalence of child overweight in low‐income student populations.

Association of optimism and pessimism with inflammation and hemostasis in the multi-ethnic study of atherosclerosis (MESA)

Objective: To investigate the association between optimism/pessimism and concentrations of seven inflammation and hemostasis markers. Optimism and pessimism are associated with cardiovascular disease mortality and progression; however, the biological mechanism remains unclear. Methods: This cross-sectional study used data from the Multi-Ethnic Study of Atherosclerosis (MESA), a study of 6814 persons aged 45 to 84 years with no history of clinical cardiovascular disease. The Life-Orientation Test-Revised (LOT-R) was used to measure dispositional optimism and pessimism. Regression analyses were used to estimate associations of optimism and pessimism with interleukin (IL)-6, C-reactive protein (CRP), fibrinogen, homocysteine, Factor VIII, D-dimer, and plasmin-antiplasmin, before and after adjustment for sociodemographics, depression, cynicism, health behaviors, body mass index (BMI), hypertension, and diabetes. Results: Higher scores on the LOT-R (positive disposition) were related to lower concentrations of IL-6 (p = .001), fibrinogen (p < .001), and homocysteine (p = .031). Associations were stronger for the pessimism subscale. After adjustment for demographics, the percentage differences in inflammatory markers corresponding to a 2-standard deviation increase in pessimism were 6.01% (p = .001) for IL-6, 10.31% (p = .001) for CRP, 2.47% (p < .0001) for fibrinogen, and 1.36% (p = .07) for homocysteine. Associations were attenuated but significant after adjustment for sociodemographics, depression, cynical distrust, and behaviors. Further adjustment for hypertension, BMI, and diabetes reduced associations for CRP and IL-6. Pessimism remained associated with a 1.36% (p = .02) increase in fibrinogen in the fully adjusted model. Factor VIII, D-dimer, and plasmin-antiplasmin were not associated with the LOT-R or subscales. Conclusions: Pessimism is related to higher levels of inflammation. Health behaviors, BMI, hypertension, and diabetes seem to play a mediating role. CVD = cardiovascular disease; CHD = coronary heart disease; MESA = Multi-Ethnic Study of Atherosclerosis; HTN = hypertension; BMI = body mass index; DM = diabetes mellitus; LOT-R = Life-Orientation Test-Revised; IL-6 = interleukin-6; CRP = C-reactive protein; CES-D = Center for Epidemiologic Studies Depression scale; HPA = hypothalamic-pituitary-adrenal; MI = myocardial infarction; SD = standard deviation.

Dietary and Activity Correlates of Sugar-Sweetened Beverage Consumption Among Adolescents

OBJECTIVE: To examine the dietary and activity correlates of sugar-sweetened beverage consumption by children in middle and high school. METHODS: Data were obtained from a cross-sectional survey of 15 283 children in middle and high schools in Texas. Consumption of sodas and noncarbonated flavored and sports beverages (FSBs) were examined separately for their associations with the level of (1) unhealthy food (fried meats, French fries, desserts) consumption, (2) healthy food (vegetables, fruit, and milk) consumption, (3) physical activity including usual vigorous physical activity and participation in organized physical activity, and (4) sedentary activity, including hours spent watching television, using the computer, and playing video games. RESULTS: For both genders, consumption of soda and FSBs was systematically associated with a number of unhealthy dietary practices and with sedentary behaviors. However, consumption of FSBs showed significant positive graded associations with several healthy dietary practices and level of physical activity, whereas soda consumption showed no such associations with healthy behaviors. CONCLUSIONS: Consumption of FSBs coexists with healthy dietary and physical activity behaviors, which suggests popular misperception of these beverages as being consistent with a healthy lifestyle. Assessment and obesity-prevention efforts that target sugar-sweetened beverages need to distinguish between FSBs and sodas.

Modeling cortisol rhythms in a population-based study.

The aim of these analyses was to develop and describe easily implementable, yet information rich, approaches for analysis of the temporal profile of cortisol in human populations. A typical waking profile of cortisol in a sample of women aged 15-44 was parameterized by a piecewise linear regression model, implemented as a mixed model to accommodate repeated observations among individuals. The model was extended to distinguish characteristic cortisol profiles of obese women from those of non-obese women. Sharp inflection points for the diurnal profile of cortisol were noted at 30 and 75 min past awakening. Obese women showed a slight tendency to have a less sharply rising and declining response to awakening than non-obese women.

Bisphenol-A and disparities in birth outcomes: a review and directions for future research

Racial disparities in pregnancy outcome in the United States are significant, persistent and costly, but the causes are poorly understood. We propose that disproportionate exposure of African-American women to environmental endocrine disrupting compounds (EDCs) may contribute to birth outcome disparities. Marked racial segregation, as well as health behaviors associated with poverty could result in differences in exposure to particular EDCs. One EDC that has aroused concern in recent years is bisphenol-A (BPA), a widely used industrial plasticizer with known estrogenic properties. Published studies indicate that excessive BPA exposure is associated with reduced fetal survival, as well as reductions in maternal weight and fetal body weight. Related findings include adverse effects of BPA exposure on ovarian function, mammary gland development, earlier age of puberty onset and some metabolic parameters. However, these findings are largely limited to experimental animal studies, and need to be validated in human populations. Our review supports the need to move beyond the currently dominant toxicological approach to examining the effects of BPA exposure, and rely more on observational human studies and epidemiological methods. Many of the risk factors for racial disparities in pregnancy outcome are global or difficult to modify, but exposure to BPA is a potentially malleable risk factor. If BPA contributes to racial disparities in pregnancy outcome, there are important implications for prevention. It is our hope that this review will stimulate further research in this important and neglected area.

Circadian rhythm of cortisol and neighborhood characteristics in a population-based sample: The Multi-Ethnic Study of Atherosclerosis

Although stress is often hypothesized to contribute to the effects of neighborhoods on health, very few studies have investigated associations of neighborhood characteristics with stress biomarkers. This study helps address the gap in the literature by examining whether neighborhood characteristics are associated with cortisol profiles. Analyses were based on data from the Multi-Ethnic Study of Atherosclerosis Stress study, which collected multiple measures of salivary cortisol over three days on a population based sample of approximately 800 adults. Multilevel models with splines were used to examine associations of cortisol levels with neighborhood poverty, violence, disorder, and social cohesion. Neighborhood violence was significantly associated with lower cortisol values at wakeup and with a slower decline in cortisol over the earlier part of the day, after sociodemographic controls. Associations were weaker and less consistent for neighborhood poverty, social cohesion, and disorder. Results revealed suggestive, though limited, evidence linking neighborhood contexts to cortisol circadian rhythms.