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Background/Objectives Non-caloric artificial sweeteners (NAS) are marketed as healthier alternatives to sugar, but the relationship between consumption of NAS and development of diabetes is unclear. This study assessed the associations of diet soda and NAS consumption with (1) early markers of insulin and glucose homeostasis (cross-sectionally) and (2) incident diabetes (over an average of 8 years of follow-up) among American Indians, a population with high rates of obesity. Subjects/Methods The study population included Strong Heart Family Study participants without cardiovascular disease or diabetes who participated in the 2007-2009 study exam (n = 1359). Diet soda and NAS consumption were assessed using a Block food frequency questionnaire and supplemental NAS questionnaire at the study exam. Fasting plasma glucose and insulin were measured during the study exam after a 12-h overnight fast. Participants were followed for incident diabetes through December 2017 using a single phone interview and medical record review; diabetes was identified by self-report and confirmed by documentation in medical records. Associations of diet soda and NAS consumption with fasting insulin, glucose, and incident diabetes were assessed using generalized estimating equations (fasting insulin and glucose analyses) and parametric survival models with Weibull distributions (incident diabetes analyses). Results Just under half of participants reported regularly consuming diet soda (40%) or using NAS to sweeten their beverages (41%). During an average 8 years of follow-up, we identified 98 cases of incident diabetes. After correction for multiple comparisons, there were no statistically significant associations of reported diet soda and NAS consumption with fasting insulin, fasting glucose, or incident diabetes. Conclusions Although reported consumption of diet soda and NAS were high, neither were associated with diabetes risk., Author(s): Paul N. Jensen [sup.1], Barbara V. Howard [sup.2], Lyle G. Best [sup.3], Marcia O'Leary [sup.3], Richard B. Devereux [sup.4], Shelley A. Cole [sup.5], Jean W. MacCluer [sup.5], Tauqeer Ali [...]

BACKGROUND: Chronic arsenic exposure has been associated with an increased risk of cardiovascular disease; diabetes; cancers of the lung, pancreas and prostate; and all-cause mortality in American Indian communities in the Strong Heart Study. OBJECTIVE: The Strong Heart Water Study (SHWS) designed and evaluated a multilevel, community-led arsenic mitigation program to reduce arsenic exposure among private well users in partnership with Northern Great Plains American Indian Nations. METHODS: A cluster randomized controlled trial (cRCT) was conducted to evaluate the effectiveness of the SHWS arsenic mitigation program over a 2-y period on a) urinary arsenic, and b) reported use of arsenic-safe water for drinking and cooking. The cRCT compared the installation of a pointof- use arsenic filter and a mobile Health (mHealth) program (3 phone calls; SHWS mHealth and Filter arm) to a more intensive program, which included this same program plus three home visits (3 phone calls and 3 home visits; SHWS Intensive arm). RESULTS: A 47% reduction in urinary arsenic [geometric mean (GM)=13.2 to 7.0 μg/g creatinine] was observed from baseline to the final follow-up when both study arms were combined. By treatment arm, the reduction in urinary arsenic from baseline to the final follow-up visit was 55% in the mHealth and Filter arm (GM=14.6 to 6.55 μg/g creatinine) and 30% in the Intensive arm (GM=11.2 to 7.82 μg/g creatinine). There was no significant difference in urinary arsenic levels by treatment arm at the final follow-up visit comparing the Intensive vs. mHealth and Filter arms: GM ratio of 1.21 (95% confidence interval: 0.77, 1.90). In both arms combined, exclusive use of arsenic-safe water from baseline to the final follow-up visit significantly increased for water used for cooking (17% to 53%) and drinking (12% to 46%). DISCUSSION: Delivery of the interventions for the community-led SHWS arsenic mitigation program, including the installation of a point-of-use arsenic filter and a mHealth program on the use of arsenic-safe water (calls only, no home visits), resulted in a significant reduction in urinary arsenic and increases in reported use of arsenic-safe water for drinking and cooking during the 2-y study period. These results demonstrate that the installation of an arsenic filter and phone calls from a mHealth program presents a promising approach to reduce water arsenic exposure among private well users. [ABSTRACT FROM AUTHOR]

BACKGROUND: Inorganic arsenic (As) may increase the risk of cardiovascular disease (CVD) and all-cause mortality through accelerated aging, which can be estimated using epigenetic-based measures. OBJECTIVES: We evaluated three DNA methylation-based aging measures (PhenoAge, GrimAge, DunedinPACE) (epigenetic aging measures) as potential mediators of the previously reported association of As exposure with CVD incidence, CVD mortality, and all-cause mortality in the Strong Heart Study (SHS), an epidemiological cohort of American Indian adults. METHODS: Blood DNA methylation and urinary As levels were measured in 2,323 SHS participants (41.5% men, mean age of 55 years old). PhenoAge and GrimAge values were calculated using a residual-based method. We tested the association of urinary As with epigenetic aging measures using linear regression, the association of epigenetic aging measures with the three health outcomes using additive hazards models, and the mediation of As-related CVD incidence, CVD mortality, and all-cause mortality by epigenetic aging measures using the product of coefficients method. RESULTS: SHS participants with higher vs. lower urinary As levels had similar PhenoAge age, older GrimAge age, and faster DunedinPACE. An interquartile range increase in urinary As was associated with higher of PhenoAge age acceleration [mean difference (95% confidence interval)=0.48 (0.17, 0.80) years], GrimAge age acceleration [0.80 (0.60, 1.00) years], and DunedinPACE [0.011 (0.005, 0.018)], after adjusting for age, sex, center location, genetic components, smoking status, and body mass index. Of the 347 incident CVD events per 100,000 person-years associated with a doubling in As exposure, 21.3% (9.1, 57.1) and 22.6% (9.5, 56.9), were attributable to differences in GrimAge and DunedinPACE, respectively. DISCUSSION: Arsenic exposure was associated with older GrimAge and faster DunedinPACE measures of biological age. Furthermore, accelerated biological aging measured from DNA methylation accounted for a relevant fraction of As-associated risk for CVD, CVD mortality, and all-cause mortality in the SHS, supporting the role of As in accelerated aging. Research of the biological underpinnings can contribute to a better understanding of the role of aging in arsenic-related disease. [ABSTRACT FROM AUTHOR]

Objectives. To compare fine particulate matter (PM2.5) concentrations in American Indian (AI)-populated with those in non–AI-populated counties over time (2000–2018) in the contiguous United States. Methods. We used a multicriteria approach to classify counties as AI- or non--AI-populated. We ran linear mixed effects models to estimate the difference in countywide annual PM2.5 concentrations from well-validated prediction models and monitoring sites (modeled and measured PM2.5, respectively) in AI- versus non–AI-populated counties. Results. On average, adjusted modeled PM2.5 concentrations in AI-populated counties were 0.38 micrograms per cubic meter (95% confidence interval [CI] = 0.23, 0.54) lower than in non–AI-populated counties. However, this difference was not constant over time: in 2000, modeled concentrations in AI-populated counties were 1.46 micrograms per cubic meter (95% CI = 1.25, 1.68) lower, and by 2018, they were 0.66 micrograms per cubic meter (95% CI = 0.45, 0.87) higher. Over the study period, adjusted modeled PM2.5 mean concentrations decreased by 2.13 micrograms per cubic meter in AI-populated counties versus 4.26 micrograms per cubic meter in non–AI-populated counties. Results were similar for measured PM2.5. Conclusions. This study highlights disparities in PM2.5 trends between AI- and non–AI-populated counties over time, underscoring the need to strengthen air pollution regulations and prevention implementation in tribal territories and areas where AI populations live. (Am J Public Health. 2022;112(4): 615–623. https://doi.org/10.2105/AJPH.2021.306650) [ABSTRACT FROM AUTHOR]

BACKGROUND: Chronic exposure to arsenic (As), a human toxicant and carcinogen, remains a global public health problem. Health risks persist after As exposure has ended, suggesting epigenetic dysregulation as a mechanistic link between exposure and health outcomes. OBJECTIVES: We investigated the association between total urinary As and locus-specific DNA methylation in the Strong Heart Study, a cohort of American Indian adults with low-to-moderate As exposure [total urinary As, mean (±SD) μg/g creatinine: 11.7 (10.6)]. METHODS: DNA methylation was measured in 2,325 participants using the Illumina MethylationEPIC array. We implemented linear models to test differentially methylated positions (DMPs) and the DMRcate method to identify regions (DMRs) and conducted gene ontology enrichment analysis. Models were adjusted for estimated cell type proportions, age, sex, body mass index, smoking, education, estimated glomerular filtration rate, and study center. Arsenic was measured in urine as the sum of inorganic and methylated species. RESULTS: In adjusted models, methylation at 20 CpGs was associated with urinary As after false discovery rate (FDR) correction (FDR< 0.05). After Bonferroni correction, 5 CpGs remained associated with total urinary As (ρBonferroni <0.05), located in SLC7A11, ANKS3, LINGO3, CSNK1D, ADAMTSL4. We identified one DMR on chromosome 11 (chr11:2,322,050-2,323,247), annotated to C11orf2; TSPAN32 genes. DISCUSSION: This is one of the first epigenome-wide association studies to investigate As exposure and locus-specific DNA methylation using the Illumina MethylationEPIC array and the largest epigenome-wide study of As exposure. The top DMP was located in SLC7A11A, a gene involved in cystine/glutamate transport and the biosynthesis of glutathione, an antioxidant that may protect against As-induced oxidative stress. Additional DMPs were located in genes associated with tumor development and glucose metabolism. Further research is needed, including research in more diverse populations, to investigate whether As-related DNA methylation signatures are associated with gene expression or may serve as biomarkers of disease development. [ABSTRACT FROM AUTHOR]

Objective: Perceptions of social-contextual food environments and associated factors that influence food purchases are understudied in American Indian (AI) communities. The purpose of the present study was to: (i) understand the perceived local food environment; (ii) investigate social-contextual factors that influence family food-purchasing choices; and (iii) identify diet intervention strategies.Design: This qualitative study consisted of focus groups with primary household shoppers and key-informant interviews with food retailers, local government food assistance programme directors and a dietitian. An inductive, constant comparison approach was used to identify major themes.Setting: A large AI reservation community in the north-central USA.Participants: Four focus groups (n 31) and seven key-informant interviews were conducted in February and May 2016.Results: Perceptions of both the higher cost of healthy foods and limited access to these foods influenced the types of foods participants purchased. Dependence on government assistance programmes and the timing of benefits also contributed to the types of foods purchased. Participants described purchasing foods based on the dietary needs and preferences of their children. Suggestions for improving the purchase and consumption of healthy foods included: culturally relevant and family-centred cooking classes and workshops focused on monthly food budgeting. Participants also emphasized the importance of involving the entire community in healthy eating initiatives.Conclusions: Cost and access were the major perceived barriers to healthy eating in this large rural AI community. Recommended interventions included: (i) family-friendly and culturally relevant cooking classes; (ii) healthy food-budgeting skills training; and (iii) approaches that engage the entire community. [ABSTRACT FROM AUTHOR]

American Indian (AI)/Alaska Native children have increased asthma prevalence, morbidity, and mortality compared to non-Hispanic white children. Our study sought to examine environmental and socioeconomic factors of asthma among children in an AI community. This case-control study included children with physician-diagnosed asthma and age-matched controls, ages 6 through 17 years, in an AI community. Diagnosis and clinical characteristics were obtained from medical record review. Home visits included interviews regarding sociodemographic and household environmental exposures, physical exams, spirometry, and asthma control questionnaires (cases only). Among the 108 asthma cases and 215 controls, 64% had an annual household income of <$25,000. Children with asthma had significantly higher odds of living in a multi-unit dwelling (odds ratio [OR], 2.3; 95% confidence interval [CI], 1.2–4.4) or in residences with rodent or insect infestation (OR, 2.1; 95% CI, 1.1–3.8) and were less likely to live in homes with more than 8 occupants (OR, 0.5; 95% CI, 0.3–0.9). Also, there was a trend for lower caregiver education level, unmarried caregiver marital status, and annual household income level of <$25,000 in univariate analysis. However, after adjustment for socioeconomic status and household environmental factors, these estimates were not significant. Nearly half of cases had poorly controlled asthma and reported persistent cough, wheeze, and dyspnea, yet only 24% reported using a controller medication. In this low-income AI community, we identified several social and environmental determinants of asthma, which were mediated by socioeconomic status and other household environmental factors, suggesting a complex interplay between socioeconomic status and environmental exposures. Furthermore, many children with asthma reported poor asthma control. [ABSTRACT FROM AUTHOR]

BACKGROUND: High arsenic exposure has been related to diabetes, but at low-moderate levels the evidence is mixed. Arsenic metabolism, which is partly genetically controlled and may rely on certain B vitamins, plays a role in arsenic toxicity. OBJECTIVE: We evaluated the prospective association of arsenic exposure and metabolism with type 2 diabetes and insulin resistance. METHODS: We included 1,838 American Indian men and women free of diabetes (median age, 36 y). Arsenic exposure was assessed as the sum of inorganic arsenic (iAs), monomethylarsonate (MMA), and dimethylarsinate (DMA) urine concentrations (ΣAs). Arsenic metabolism was evaluated by the proportions of iAs, MMA, and DMA over their sum (iAs%, MMA%, and DMA%). Homeostasis model assessment for insulin resistance (HOMA2-IR) was measured at baseline and follow-up visits. Incident diabetes was evaluated at follow-up. RESULTS: Median ΣAs, iAs%, MMA%, and DMA% was 4:4 lg=g creatinine, 9.5%, 14.4%, and 75.6%, respectively. Over 10,327 person-years of follow-up, 252 participants developed diabetes. Median HOMA2-IR at baseline was 1.5. The fully adjusted hazard ratio [95% confidence interval (CI)] for incident diabetes per an interquartile range increase in ΣAs was 1.57 (95% CI: 1.18, 2.08) in participants without prediabetes at baseline. Arsenic metabolism was not associated with incident diabetes. ΣAs was positively associated with HOMA2-IR at baseline but negatively with HOMA2-IR at follow-up. Increased MMA% was associated with lower HOMA2-IR when either iAs% or DMA% decreased. The association of arsenic metabolism with HOMA2-IR differed by B-vitamin intake and AS3MT genetics variants. CONCLUSIONS: Among participants without baseline prediabetes, arsenic exposure was associated with incident diabetes. Low MMA% was cross-sectional and prospectively associated with higher HOMA2-IR. Research is needed to confirm possible interactions of arsenic metabolism with B vitamins and AS3MT variants on diabetes risk. [ABSTRACT FROM AUTHOR]

BACKGROUND: Metabolism of inorganic arsenic (iAs) is subject to inter-individual variability, which is explained partly by genetic determinants. OBJECTIVES: We investigated the association of genetic variants with arsenic species and principal components of arsenic species in the Strong Heart Family Study (SHFS). METHODS: We examined variants previously associated with cardiometabolic traits (~200,000 from Illumina Cardio MetaboChip) or arsenic metabolism and toxicity (670) among 2,428 American Indian participants in the SHFS. Urine arsenic species were measured by high performance liquid chromatography -- inductively coupled plasma mass spectrometry (HPLC-ICP-MS), and percent arsenic species [iAs, monomethylarsonate (MMA), and dimethylarsinate (DMA), divided by their sum x 100] were logit transformed. We created two orthogonal principal components that summarized iAs, MMA, and DMA and were also phenotypes for genetic analyses. Linear regression was performed for each phenotype, dependent on allele dosage of the variant. Models accounted for familial relatedness and were adjusted for age, sex, total arsenic levels, and population stratification. Single nucleotide polymorphism (SNP) associations were stratified by study site and were meta-analyzed. Bonferroni correction was used to account for multiple testing. RESULTS: Variants at 10q24 were statistically significant for all percent arsenic species and principal components of arsenic species. The index SNP for iAs%, MMA%, and DMA% (rsl2768205) and for the principal components (rs3740394, rs3740393) were located near AS3MT, whose gene product catalyzes methylation of iAs to MMA and DMA. Among the candidate arsenic variant associations, functional SNPs in AS3MTand 10q24 were most significant (p < 9.33 x 10[sup -5]). CONCLUSIONS: This hypothesis-driven association study supports the role of common variants in arsenic metabolism, particularly AS3MT and 10q24. CITATION: Balakrishnan P, Vaidya D, Franceschini N, Voruganti VS, Gribble MO, Haack K, Laston S, Umans JG, Francesconi KA, Goessler W, North KE, Lee E, Yracheta J, Best LG, MacCluer JW, Kent J Jr., Cole SA, Navas-Acien A. 2017. Association of cardiometabolic genes with arsenic metabolism biomarkers in American Indian communities: the Strong Heart Family Study (SHFS). Environ Health Perspect 125:15-22; http://dx.doi.org/10.1289/EHP251 [ABSTRACT FROM AUTHOR]

Background: Asthma is recognized as intimately related to immunologic factors and inflammation, although there are likely multiple phenotypes and pathophysiologic pathways. Biomarkers of inflammation may shed light on causal factors and have potential clinical utility. Individual and population genetic factors are correlated with risk for asthma and improved understanding of these contributions could improve treatment and prevention of this serious condition.Methods: A population-based sample of 108 children with clinically defined asthma and 216 control children were recruited from a small community in the northern plains of the United States. A complete blood count, high sensitivity C-reactive protein, total IgE and specific antibodies to 5 common airborne antigens (CAA), in addition to basic demographic and anthropomorphic data were obtained. Logistic regression was primarily used to determine the association between these humoral factors and risk of asthma.Results: The body mass index (BMI) of those with asthma and their total leukocyte counts, percentage of eosinophils, and levels of total IgE were all greater than corresponding control values in univariate analysis. The presence of detectable, specific IgE antibodies to five common airborne antigens was more likely among cases compared with controls. In multivariate analysis, total IgE was independently associated with asthma; but not after inclusion of a cumulative measure of specific IgE sensitization.Conclusion: Many previously reported associations between anthropomorphic and immune factors and increased risk of asthma appear to be also present in this American Indian population. In this community, asthma is strongly associated with sensitization to CAA. [ABSTRACT FROM AUTHOR]

The etiology of pre-eclampsia (PE) is unknown; but it has been long acknowledged that normal pregnancy represents a distinctive challenge to the maternal immune system. Maladaptive responses to this challenge [...]

Background: The etiology of pre-eclampsia (PE) is unknown; but it is accepted that normal pregnancy represents a distinctive challenge to the maternal immune system. C-reactive protein is a prominent component of the innate immune system; and we previously reported an association between PE and the CRP polymorphism, rs1205. Our aim was to explore the effects of additional CRP variants. The IBC (Cardiochip) genotyping microarray focuses on candidate genes and pathways related to the pathophysiology of cardiovascular disease. Methods: This study recruited 140 cases of PE and 270 matched controls, of which 95 cases met criteria as severe PE, from an American Indian community. IBC array genotypes from 10 suitable CRP SNPs were analyzed. A replication sample of 178 cases and 427 controls of European ancestry was also genotyped. Results: A nominally significant difference (p value <0.05) was seen in the distribution of discordant matched pairs for rs3093068; and Bonferroni corrected differences (P<0.005) were seen for rs876538, rs2794521, and rs3091244. Univariate conditional logistic regression odds ratios (OR) were nominally significant for rs3093068 and rs876538 models only. Multivariate logistic models with adjustment for mother's age, nulliparity and BMI attenuated the effect (OR 1.58, P = 0.066, 95% CI 0.97–2.58) for rs876538 and (OR 2.59, P = 0.050, 95% CI 1.00–6.68) for rs3093068. An additive risk score of the above two risk genotypes shows a multivariate adjusted OR of 2.04 (P = 0.013, 95% CI 1.16–3.56). The replication sample also demonstrated significant association between PE and the rs876538 allele (OR = 1.55, P = 0.01, 95% CI 2.16–1.10). We also show putative functionality for the rs876538 and rs3093068 CRP variants. Conclusion: The CRP variants, rs876538 and rs3093068, previously associated with other cardiovascular disease phenotypes, show suggestive association with PE in this American Indian population, further supporting a possible role for CRP in PE. [ABSTRACT FROM AUTHOR]

Objective. To determine the prevalence in an American Indian population of genetic variants with putative effects on endothelial function and determine whether they are associated with preeclampsia. Methods. Five genetic polymorphisms potentially related to endothelial function in the NOS3, GNB3, and DDAH1 genes were genotyped from a total of 101 cases, 198 controls, and an additional 110 population-based controls among an American Indian population. Results. The minor allele frequencies for NOS3 (rs1799983, rs3918227), GNB3 (rs5442), and DDAH1 (rs10158674, rs233115) among those with and without PE in this population were 25, 10, 5, 11, and 30%%, respectively. Although not statistically significant, the maximum risk associated with any of these SNPs was 2.22 (0.734-6.73, 95%% CI, p == 0.156) in a multivariate analysis of the A allele of the rs233115 SNP incorporated in a recessive model. Conclusion. Although endothelial dysfunction likely plays a role in the pathophysiology of PE, this study was unable to find evidence for an association between these five SNPs on three genes influencing endothelial function and PE. This may be due to insufficient power to detect an association, investigation of SNPs without linkage to risk of PE in this population or other factors. Investigation of additional SNPs in these or related genes and other populations seems warranted. [ABSTRACT FROM AUTHOR]

The article focuses on a study which analyzed the genetic variation that influence serum bilirubin levels in American Indians. Study authors conducted genome-wide screening and association analyses among 3,484 American Indians, aged 14 to 93 years, from Oklahoma, Arizona and north and South Dakota. The genetic association of uridine diphosphate glucuronosyltransferase (UGTIA1) promoter polymorphism was found in all locations.

Objective: To determine the prevalence of thrombophilic genetic variants in an American Indian population and determine if they are associated with preeclampsia.Methods: A total of 87 cases, 165 controls and an additional 75 population-based controls were genotyped for two thrombophilic polymorphisms.Results: The allelic prevalence of the factor V Leiden and 20210 G/A prothrombin variants in this population was 2.1% and 0.5% respectively. No statistically significant associations between these genetic variants and preeclampsia were found.Conclusion: The prevalence of thrombophilic variants is of possible public health significance for other morbidity; but perhaps not in relation to preeclampsia. [ABSTRACT FROM AUTHOR]

Background: Type 2 diabetes (T2D) is characterized by profound metabolic abnormalities. Current glycemic indicators have limitations in identifying early metabolic alterations. Objective: To identify novel metabolic predictors of T2D in American Indians participating in the Strong Heart Family Study. Methods: Among 2,129 participants who had normal fasting glucose (NFG) at baseline (2001-2003) and also attended clinical examination after 5-year follow-up (2006-2009), 142 developed incident T2D, 514 developed incident impaired fasting glucose (IFG), and 1,473 remained to be NFG. The current analysis included all incident cases of T2D (n=142), 146 incident IFG (randomly selected from 514 participants with incident IFG) and 144 NFG (randomly selected from 1,473 participants with NFG at both visits). Baseline plasma metabolites were detected by high-resolution LC/MS. The prospective association of each metabolite with risk for T2D or IFG was investigated using weighted Cox's hazard regression with frailty model, adjusting for sex, study center, age, BMI, renal function, fasting glucose and fasting insulin at baseline. Multiple testing was corrected by Bonferroni correction (significance level 2.8 10-6). Results: Thirty-nine metabolites from several major fuel sources, including sugar amino acids, amino acids, lipids, alkaloids, alkylamines, carboxylic acids, steroids, and aromatic homomonocylic/heteropolycyclic compounds, significantly predicted future risk of T2D (10 metabolites), or IFG (27 metabolites), or both (2 metabolites). Of these, N1,N12-diacetylspermine and betanidin, respectively, were the strongest predictors for increased (HR=4.59, 95% CI, 2.55-8.24, P=3.49 10-7) and decreased risk of T2D (HR=0.38, 95% CI, 0.28-0.52, P=4.64 10-10). The corresponding strongest predictors for IFG were hexanoic acid (HR=2.34, 95% CI, 1.84-2.98, P=3.15 10-12) and l-palmitoylcarnitine (HR=0.26, 95% CI, 0.18-0.37, P=1.14 10-13), respectively. Two metabolites, betanidin and dopamine, significantly predicted future onset of both T2D (HR=0.38, 95% CI, 0.28,0.52, P=4.64 10-10 for betanidin; HR=2.48, 95% CI, 1.71-3.58, P=1.42 10-6 for dopamine) and IFG (HR=0.52, 95% CI, 0.43,0.62, P=1.35 10-12 for betanidin; HR=2.24, 95% CI, 1.73,2.89, P=5.79 10-10 for dopamine). Multiple unknown compounds were also independently associated with risk of T2D, IFG or both. Conclusions: This study identifies both novel and known metabolic alterations associated with risk of diabetes in American Indians, an ethnic group suffering from disproportionately high rates of T2D. The incomplete overlapping of metabolic profiles between T2D and IFG highlights differential metabolic states of diabetes development. Our results not only provide novel insights in disease pathogenesis but also valuable data on potential new targets for risk prediction and treatment. [ABSTRACT FROM AUTHOR]

Objective: Gene × diet interaction plays an important role in atherosclerosis, an inflammatory disorder. Leukotrienes are the most potent inflammatory mediators, and genetic variants encoding leukotriene genes have been implicated in atherosclerosis. This study tests nutrigenetic interaction of a previously defined leukotriene haplotype on carotid artery hypertrophy and atherosclerosis in American Indians. Methods: This study included 3402 American Indians participating in the Strong Heart Family Study (SHFS). Carotid artery measurements, including intima-media thickness (IMT), vascular mass, and plaque, were assessed using ultrasound. Eleven tagSNPs in the leukotriene A4 hydrolase (LTA4H) gene were genotyped in all subjects. Main haplotype effect and haplotype × diet interaction were examined by generalized estimating equation, adjusting for known risk factors. Results: There was no significant main effect of haplotype or diet on any of the carotid artery measures. However, a previously defined LTA4H haplotype, called HapE, significantly interacted with dietary intake of n-3 and n-6 fatty acids on both IMT (P HapE×n3 = 0.018, P HapE×n6 = 0.040) and vascular mass (P HapE×n3 = 0.012, P HapE×n6 = 0.018), but not plaque. The direction of this nutrigenetic interaction on IMT was consistent with that reported in a recent study of Caucasian twins. Conclusion: Dietary intake of polyunsaturated fatty acids significantly modifies the effect of a leukotriene haplotype on carotid artery hypertrophy but not atherosclerosis in American Indians, independent of established cardiovascular risk factors. Replication of nutrigenetic interaction in two distinct ethnic groups suggests the robustness and generalizability of our findings to diverse populations. [ABSTRACT FROM AUTHOR]

Telomeres play a central role in cellular aging, and shorter telomere length has been associated with age-related disorders including diabetes. However, a causal link between telomere shortening and diabetes risk has not been established. In a well-characterized longitudinal cohort of American Indians participating in the Strong Heart Family Study, we examined whether leukocyte telomere length (LTL) at baseline predicts incident diabetes independent of known diabetes risk factors. Among 2,328 participants free of diabetes at baseline, 292 subjects developed diabetes during an average 5.5 years of follow-up. Compared with subjects in the highest quartile (longest) of LTL, those in the lowest quartile (shortest) had an almost twofold increased risk of incident diabetes (hazard ratio [HR] 1.83 [95% CI 1.26-2.66]), whereas the risk for those in the second (HR 0.87 [95% CI 0.59-1.29]) and the third (HR 0.95 [95% CI 0.65-1.38]) quartiles was statistically nonsignificant. These findings suggest a nonlinear association between LTL and incident diabetes and indicate that LTL could serve as a predictive marker for diabetes development in American Indians, who suffer from disproportionately high rates of diabetes. [ABSTRACT FROM AUTHOR]

OBJECTIVE--Prevalence of insulin resistance is high in the American Indian population, likely as a result of the high prevalence of obesity. This condition may be influential for clinical outcomes such as cardiovascular disease (CVD) and decreased kidney function. RESEARCH DESIGN AND METHODS--Normal glucose tolerant (NGT) participants free of hypertension and CVD at the baseline examination (1989-1992) (N = 964) of the Strong Heart Study were selected to explore the cross-sectional association between insulin resistance quantified by homeostasis model assessment (HOMA-IR) and demographic, behavioral, and cardiometabolic variables. The longitudinal association between baseline HOMA-IR and the development of CVD was also explored. The longitudinal association between baseline HOMA-IR and the development of high urinary albumin-to-creatinine ratio was explored among nondiabetic participants (N = 1,401). RESULTS--Cross-sectionally, HOMA-IR was associated with sex, residence location, smoking, and high-risk cardiometabolic profile. Prospectively, insulin resistance is associated with the development of CVD and decreased kidney function in this population. CONCLUSIONS--Insulin resistance may have an important role in the pathogenesis of CVD and chronic kidney disease. Since obesity contributes to the development of insulin resistance, intervention focusing on modifiable factors such as physical activity and weight control may reduce the development of these diseases. [ABSTRACT FROM AUTHOR]

Type 2 diabetes is highly prevalent and is the major cause of progressive chronic kidney disease in American Indians. Genome-wide association studies identified several loci associated with diabetes but their impact on susceptibility to diabetic complications is unknown. We studied the association of 18 type 2 diabetes genome-wide association single-nucleotide polymorphisms (SNPs) with estimated glomerular filtration rate (eGFR; MDRD equation) and urine albumin-to-creatinine ratio in 6958 Strong Heart Study family and cohort participants. Center-specific residuals of eGFR and log urine albumin-to-creatinine ratio, obtained from linear regression models adjusted for age, sex, and body mass index, were regressed onto SNP dosage using variance component models in family data and linear regression in unrelated individuals. Estimates were then combined across centers. Four diabetic loci were associated with eGFR and one locus with urine albumin-to-creatinine ratio. A SNP in the WFS1 gene (rs10010131) was associated with higher eGFR in younger individuals and with increased albuminuria. SNPs in the FTO, KCNJ11, and TCF7L2 genes were associated with lower eGFR, but not albuminuria, and were not significant in prospective analyses. Our findings suggest a shared genetic risk for type 2 diabetes and its kidney complications, and a potential role for WFS1 in early-onset diabetic nephropathy in American Indian populations. [ABSTRACT FROM AUTHOR]

American Indians have a disproportionately high rate of kidney disease likely due to a combination of environmental and genetic factors. We performed a genome wide scan of estimated glomerular filtration rate in 3665 participants of the Strong Heart Family Study to localize genes influencing kidney disease risk factors. The participants were men and women from 13 American Indian tribes recruited from 3 centers located in Arizona, the Dakotas and Oklahoma. Multipoint variance component linkage analysis was performed for each center and on the entire cohort after controlling for center effects. Modeling strategies that incorporated age, gender and interaction terms (model 1) and another that also controlled for diabetes mellitus, systolic and diastolic blood pressure, body mass index, low density and high density lipoproteins, triglycerides and smoking status (model 2) were used. Significant evidence for linkage in the Arizona group was found on chromosome 12p12.2 at 39cM (nearest marker D12S310) using model 1. Additional loci with very suggestive evidence for linkage were detected at 1p36.31 for all groups using both models and at 2q33.3 and 9q34.2 for the Dakotas group each using model 1. No significant evidence for additive interaction with diabetes, hypertension or obesity was noted. This evidence for linkage of a quantitative trait locus influencing estimated glomerular filtration rate to a region of chromosome 12p in a large cohort of American Indians will be worth studying in more detail in the future.Kidney International (2008) 74, 1185–1191; doi:10.1038/ki.2008.410; published online 13 August 2008 [ABSTRACT FROM AUTHOR]

OBJECTIVE: To determine whether triglyceride to HDL cholesterol (TG/HDL) ratio is a predictor of incident stroke in diabetic patients and in non-diabetics. Elevated TG/HDL ratio has been shown to be related to insulin resistance. Less is known about its association with subsequent stroke occurrence. METHODS: The Strong Heart Study is a large population-based prospective study of CVD in 13 American Indian communities in Arizona, Oklahoma, and South/North Dakota. The baseline examination between 1989 and 1992 consisted of a personal interview, a physical exam, and lab tests, including serum fasting lipid measures. A total of 4,415 participants aged 45-74 years were free of stroke at baseline and were followed for a mean of 14 years. Diabetes status was determined based on World Health Organization recommendations. Incident stroke events were identified through medical records or patient medical histories and confirmed by a committee of blinded experts on CVD. Univariate and multivariate (Cox proportional hazard models) methods were used to analyze the data. RESULTS: Validated incident stroke cases totaled 248 participants as of December 2003. It was found that in diabetic patients, the incidence of stroke increased with higher TG/HDL ratio (p for trend < 0.04). With adjustment for age, gender, body mass index, smoking, hypertension, albuminuria, and LDL cholesterol, the second quartile was associated with a 1.4-fold (95% confidence interval (CI): 0.9-2.3) higher incidence of stroke, compared to the first (lowest) quartile. The third quartile was associated with a 1.5-fold (CI: 1.0-2.4) higher incidence, and the fourth (highest) quartile was associated with a 1.4-fold (CI: 0.8-2.2) higher incidence of stroke. In non-diabetic individuals, TG/HDL ratio was not significantly associated with risk of stroke (p for trend = 0.8). CONCLUSION: These findings suggest that elevated triglyceride to HDL cholesterol ratio, a simple dyslipidemia measure shown to be related to insulin resistance, might be useful to predict the risk of subsequent stroke in diabetics. [ABSTRACT FROM AUTHOR]