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1.  Self-Rated Health Among Adult Women of Mexican Origin 
Self-rated health (SRH), a consistent predictor of mortality among diverse populations, is sensitive to health indicators and social factors. American-born Hispanics report better SRH than their foreign-born counterparts but simultaneously report poorer health indicators and have shorter life expectancy. Using a matched prospective cross-sectional design, we analyzed data from 631 age-matched pairs of women, born in the United States or Mexico, enrolled in a cohort study based in Houston, Texas. Our first goal was to describe the relationships between SRH and health behaviors, physician-diagnosed chronic conditions, acculturation, and socioeconomic status (SES) by birthplace. Our second goal was to investigate the relative influence of SES, acculturation, health behaviors, and physician-diagnosed conditions in explaining expected differences in SRH between the two groups. Number of chronic conditions reported, particularly depression, more strongly influenced SRH than SES, acculturation, or reported health risk behaviors and the influence of birthplace is accounted for by these factors.
PMCID: PMC3940416  PMID: 24600161
Self-rated health; acculturation; SES; health indicators
2.  Sensation seeking genes and physical activity in youth 
Genes, brain, and behavior  2012;12(2):181-188.
Many studies examining genetic influences on physical activity (PA) have evaluated the impact of single nucleotide polymorphisms (SNPs) related to the development of lifestyle-related chronic diseases, under the hypothesis that they would be associated with PA. However, PA is a multi-determined behavior and associated with a multitude of health consequences. Thus, examining a broader range of candidate genes associated with a boarder range of PA correlates may provide new insights into the genetic underpinnings of PA. In this study we focus on one such correlate – sensation seeking behavior. Participants (N=1,130 Mexican origin youth) provided a saliva sample and data on PA and sensation seeking tendencies in 2008–09. Participants were genotyped for 630 functional and tagging variants in the dopamine, serotonin, and cannabinoid pathways. Overall 30% of participants (males – 37.6%; females – 22.0%) reported ≥60 minutes of PA on five out of seven days. After adjusting for gender, age and population stratification, and applying the Bayesian False Discovery Probability approach for assessing noteworthiness, four gene variants were significantly associated with PA. In a multivariable model, being male, having higher sensation seeking tendencies and at least one copy of the minor allele for SNPs in ACE (rs8066276 OR=1.44; p=0.012) and TPH2 (rs11615016 OR=1.73; p=0.021) were associated with increased likelihood of meeting PA recommendations. Participants with at least one copy of the minor allele for SNPs in SNAP25 (rs363035 OR=0.53; p=0.005) and CNR1 (rs6454672 OR=0.62; p=0.022) have decreased likelihood of meeting PA recommendations. Our findings extend current knowledge of the complex relationship between PA and possible genetic underpinnings.
PMCID: PMC3581711  PMID: 23190435
Physical Activity; Genes; Sensation Seeking; Mexican origin youth
3.  Cigarette Experimentation in Mexican Origin Youth: Psychosocial and Genetic Determinants 
Established psychosocial risk factors increase the risk for experimentation among Mexican-origin youth. Now we comprehensively investigate the added contribution of select polymorphisms in candidate genetic pathways associated with sensation seeking, risk taking, and smoking phenotypes to predict experimentation.
Participants, (N=1,118 Mexican origin youth) recruited from a large population-based cohort study in Houston, Texas, provided prospective data on cigarette experimentation over three years. Psychosocial data were elicited twice—baseline and final follow-up. Participants were genotyped for 672 functional and tagging variants in the dopamine, serotonin and opioid pathways.
After adjusting for gender and age, with a Bayesian False Discovery Probability set at 0.8 and prior probability of 0.05, six gene variants were significantly associated with risk of experimentation. After controlling for established risk factors, multivariable analyses revealed that participants with six or more risk alleles were 2.25 (95%CI: 1.62–3.13) times more likely to have experimented since baseline compared to participants with five or fewer. Among committed never smokers (N=872), three genes (OPRM1, SNAP25, HTR1B) were associated with experimentation as were all psychosocial factors. Among susceptible youth (N=246) older age at baseline, living with a smoker, and three different genes (HTR2A, DRD2, SLC6A3) predicted experimentation.
Our findings, which have implications for development of culturally-specific interventions, need to be validated in other ethnic groups.
These results suggest that variations in select genes interact with a cognitive predisposition toward smoking. In susceptible adolescents, the impact of the genetic variants appears to be larger compared to committed never smokers.
PMCID: PMC3382046  PMID: 22028400
4.  Cognitive Susceptibility to Smoking: Two Paths to Experimenting among Mexican Origin Youth 
Cognitive susceptibility to smoking, defined as the lack of a firm commitment not to smoke in the future or if offered a cigarette by a friend, begins in childhood and is an early phase in the transition from never to ever smoking. Our objectives were to examine susceptibility to smoking and other psychosocial risk factors for experimentation with cigarettes among Mexican origin adolescents and to determine whether susceptibility status moderates the relationship between established risk factors for experimentation with cigarettes and future experimentation. We examined susceptibility and several psychosocial factors associated with susceptibility as baseline predictors of experimentation after 3 years of follow-up among 964 Mexican origin girls and boys between 11 and 13 years of age from the Houston metropolitan area. Participants were recruited between May 2005 and October 2006 and reported that they had never experimented with cigarettes at baseline. Baseline susceptibility and experimentation rates were 23% and 9%, respectively, whereas the follow-up experimentation rate, among those who had not experimented at baseline, was 22%. Susceptible adolescents at baseline were 2.6 times more likely to have experimented with cigarettes by follow-up. Baseline susceptibility moderated the relationship between experimentation at follow-up and the psychosocial risk factors assessed at baseline. Susceptibility is a valid and strong marker for the transition to experimentation for Mexican origin adolescents. Our results suggest that tailoring primary prevention programs by a youth’s susceptibility status may increase the efficacy of prevention efforts among Mexican origin youth.
PMCID: PMC3183967  PMID: 19959696
5.  The evolving discipline of molecular epidemiology of cancer 
Carcinogenesis  2009;31(1):127-134.
Classical epidemiologic studies have made seminal contributions to identifying the etiology of most common cancers. Molecular epidemiology was conceived of as an extension of traditional epidemiology to incorporate biomarkers with questionnaire data to further our understanding of the mechanisms of carcinogenesis. Early molecular epidemiologic studies employed functional assays. These studies were hampered by the need for sequential and/or prediagnostic samples, viable lymphocytes and the uncertainty of how well these functional data (derived from surrogate lymphocytic tissue) reflected events in the target tissue. The completion of the Human Genome Project and Hapmap Project, together with the unparalleled advances in high-throughput genotyping revolutionized the practice of molecular epidemiology. Early studies had been constrained by existing technology to use the hypothesis-driven candidate gene approach, with disappointing results. Pathway analysis addressed some of the concerns, although the study of interacting and overlapping gene networks remained a challenge. Whole-genome scanning approaches were designed as agnostic studies using a dense set of markers to capture much of the common genome variation to study germ-line genetic variation as risk factors for common complex diseases. It should be possible to exploit the wealth of these data for pharmacogenetic studies to realize the promise of personalized therapy. Going forward, the temptation for epidemiologists to be lured by high-tech ‘omics’ will be immense. Systems Epidemiology, the observational prototype of systems biology, is an extension of classical epidemiology to include powerful new platforms such as the transcriptome, proteome and metabolome. However, there will always be the need for impeccably designed and well-powered epidemiologic studies with rigorous quality control of data, specimen acquisition and statistical analysis.
PMCID: PMC2802669  PMID: 20022891
6.  Exposure to Smoking Imagery in the Movies and Experimenting with Cigarettes among Mexican Heritage Youth 
There is growing evidence that an adolescent’s decision to try cigarettes is influenced by level of exposure to movies in which smoking is portrayed. Less is known about how ethnicity affects this process. We examined whether acculturation and/or country of birth influence the relationship between exposure to smoking imagery in the movies and experimenting with cigarettes among Mexican origin youth. We prospectively followed 1,328 Mexican origin adolescents aged 11–13 at baseline. We assessed which of 50 movies (randomly selected from a pool of 250 popular contemporary movies released from 1999–2004 and content analyzed for smoking) adolescents had seen. Smoking behavior was assessed at baseline and at 6-month intervals over 24 months. 10% of the adolescents had experimented at baseline; 17% tried subsequently. Multivariate analyses revealed, as exposure to smoking imagery in the movies increased, the chances of having ever experimented (AOR=1.27; 95% CI: 1.10–1.48) and of being a new experimenter (AOR=1.19; 95% CI: 1.01–1.40) increased, equivalent to a 4.2% increased risk of ever and a 3.0% increased risk of new experimenting for each additional quartile of movie exposure. This effect was moderated by country of birth. For Mexican-born youth, exposure to smoking imagery in the movies was the strongest independent predictor of new experimentation (AOR=1.52; 95% CI: 1.14–2.05). For US-born youth, we observed a ceiling effect: the percent of experimenters increased with increasing exposure, and then flattened. Among Mexican-born youth exposure to smoking imagery in the movies may be an important part of the acculturation process associated with smoking initiation.
PMCID: PMC2791895  PMID: 19959693
Experimenting with cigarettes; exposure to smoking imagery; Mexican origin youth
7.  The influence of subjective social status on the relationship between positive outcome expectations and experimentation with cigarettes 
In Texas, Mexican American (MA) adolescents, and in particular boys, are at increased risk of experimenting with cigarettes compared to their black or white counterparts. Positive outcome expectations (POE), the functional social significance ascribed to cigarettes, and subjective social status (SSS), the adolescents’ subjective views of where they lie in the school-based social hierarchy, are independent predictors of smoking. The goal of this study was to test the hypothesis that SSS moderates the relationship between POE and experimentation with cigarettes.
Moderating effects of SSS were examined using a between-subjects 2 by 2 ANOVA and unconditional logistic regression analyses. Using a prospective study design, we followed 1,142 MA adolescents aged 11 to 13. Participants completed a baseline survey at home, which assessed POE, SSS, and smoking and were followed via telephone at 6 monthly intervals over a 12 month period to assess changes in smoking behavior.
At follow-up, there were 99 new experimenters. Consistent with our hypothesis, adolescents who reported moderate-low SSS and who held POE at baseline were more likely to have experimented with cigarettes at either follow-up than their peers with moderate-low SSS who held less POE (OR=1.92, CI: 1.02–3.58). There was no association between outcome expectations and experimenting among adolescents with high SSS (OR=1.79, CI: 0.73–4.36). Low SSS boys were more likely to experiment than girls and high SSS boys.
The results of this study indicate that adolescents with moderate-low SSS hold different outcome expectations about smoking than their higher SSS peers. The results underscore the possibility that moderate-low SSS adolescents view behaviors such as smoking as a way to achieve higher SSS and thereby increase their peer social standing. Our results suggest that, in addition to tailoring intervention efforts by gender, placing adolescents of similar social standing to one another within the school into intervention groups that are led by a peer-nominated peer may increase the overall effectiveness of these peer-led prevention efforts.
PMCID: PMC2705959  PMID: 19306792

Results 1-7 (7)