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1.  Association of Blood and Hair Mercury with Blood Pressure and Vascular Reactivity 
Some studies suggest that high levels of blood and hair mercury (Hg) increase the risk of atherothrombotic diseases, an effect that may be explained by oxidative damage to the vascular endothelium.
We tested whether high Hg levels impair the vasodilating function of the vascular endothelium or increase blood pressure.
We measured the association between high blood and hair Hg and brachial artery flow mediated vasodilation (FMD%), middle cerebral artery reactivity to CO2 (MCAR%) and hypertensive status in 101 participants in the Wisconsin Sleep Cohort Study (mean age of 59.4 years; 52.5% male). Whole blood total Hg and hair total Hg were tested using inductively coupled plasma mass spectrometry and cold vapor atomic fluorescence spectrometry, respectively.
Geometric mean blood and hair Hg were 1.16 µg/L and 270.1 ng/g. Blood and hair Hg were not significantly associated with FMD% and MCAR%. However, after adjustment for other risk factors, people in the upper quartile of blood Hg were 1.9 times (P=0.23) more likely to be hypertensive and those in the upper quartile of hair Hg were more than 4 times more likely (P=0.02).
High hair and blood Hg levels do not seem to influence vascular reactivity, but may increase the risk of hypertension.
PMCID: PMC4593490  PMID: 19743756
2.  Symptoms of depression and anxiety and adherence to antihypertensive medication 
American Journal of Hypertension  2012;25(4):505-511.
Nonadherence to drug treatment is a major contributor to antihypertensive treatment failure. Mood disorders could impair the patient's desire and ability to follow physician's recommendations. We evaluated the role of symptoms of depression and anxiety on adherence to antihypertensive drug treatment.
We conducted a longitudinal cohort study in 20–70 years old patients starting antihypertensive drug treatment, without other chronic conditions, and not taking mood-modifying drugs. Severity of symptoms of depression and anxiety were evaluated at enrollment and 3, 6, 9, and 12 months of follow-up, using the Beck depression inventory-II (BDI-II) and the psychological general well-being index (PGWB), respectively. Treatment adherence was measured by pill count. Nonadherence was defined as taking <80% of the prescribed number of pills. Poisson regression was used to model the association of the exposures with adherence.
We enrolled 178 patients (58% male; mean age: 50 years; 508 follow-up visits). The risk of nonadherence was 52.6% in 12 months (95% confidence interval (CI): 46.1, 59.1). After adjusting for other risk factors, individuals with at least mild depression (BDI-II ≥14) and those with at least mild anxiety (PGWB anxiety score <22) were 2.48 (95% CI: 1.47, 4.18) and 1.59 (95% CI: 0.99, 2.56) times more likely to become nonadherent in the following 3 months, respectively.
Patients with at least mild anxiety and depression symptoms are at increased risk of becoming nonadherent to antihypertensive medication. Screening for depression and anxiety symptoms could be used to identify high-risk patients. Further evidence is needed to elucidate whether interventions targeting these conditions improve adherence.
PMCID: PMC3588114  PMID: 22258334
anxiety; blood pressure; cohort studies; depression; hypertension; pateint non-adherence
3.  Environmental and occupational health research and training needs in Colombia: A Delphi study 
Environmental factors contribute with 16% of the burden of disease in Colombia. A main obstacle in implementing national and regional environmental and occupational health policies is the limited knowledge on the local ability to study and control the impact of harmful exposures on health.
To identify needs for research and training in environmental and occupational health in Colombia.
Materials and methods
We conducted a three-round hybrid Delphi study. A group of environmental and occupational health Colombian experts (n=16) from government agencies, universities, and research centers was recruited to participate in the study. Expert’s opinions on research and training needs were gathered through online questionnaires, followed by an in-person meeting. The percentage of agreement and the coefficient of variation were used to measure consensus.
Air pollution and chemical products were considered the most important environmental and occupational exposures, due to their significant impact on chronic non-communicable diseases, such as respiratory diseases, cardiovascular diseases, and cancer. Research on the effects of outdoor air pollution on cardiovascular and respiratory diseases was considered of the greatest importance. Priority training areas included environmental and occupational health risk assessment, exposure modeling, advanced statistical methods, urban planning, occupational safety and hygiene, and epidemiology and toxicology.
These findings provide a valuable input for the definition and implementation of national environmental and occupational health policies and for the development of a regional hub aimed at strengthening the capacity for research and training in Colombia.
PMCID: PMC4665107  PMID: 26535742
Environmental health; occupational health; research; education; Colombia
4.  Major Cardiovascular Risk Factors in Latin America: A Comparison with the United States. The Latin American Consortium of Studies in Obesity (LASO) 
PLoS ONE  2013;8(1):e54056.
Limited knowledge on the prevalence and distribution of risk factors impairs the planning and implementation of cardiovascular prevention programs in the Latin American and Caribbean (LAC) region.
Methods and Findings
Prevalence of hypertension, diabetes mellitus, abnormal lipoprotein levels, obesity, and smoking were estimated from individual-level patient data pooled from population-based surveys (1998–2007, n = 31,009) from eight LAC countries and from a national survey of the United States (US) population (1999–2004) Age and gender specific prevalence were estimated and age-gender adjusted comparisons between both populations were conducted. Prevalence of diabetes mellitus, hypertension, and low high-density lipoprotein (HDL)-cholesterol in LAC were 5% (95% confidence interval [95% CI]: 3.4, 7.9), 20.2% (95% CI: 12.5, 31), and 53.3% (95% CI: 47, 63.4), respectively. Compared to LAC region’s average, the prevalence of each risk factor tended to be lower in Peru and higher in Chile. LAC women had higher prevalence of obesity and low HDL-cholesterol than men. Obesity, hypercholesterolemia, and hypertriglyceridemia were more prevalent in the US population than in LAC population (31 vs. 16.1%, 16.8 vs. 8.9%, and 36.2 vs. 26.5%, respectively). However, the prevalence of low HDL-cholesterol was higher in LAC than in the US (53.3 vs. 33.7%).
Major cardiovascular risk factors are highly prevalent in LAC region, in particular low HDL-cholesterol. In addition, marked differences do exist in this prevalence profile between LAC and the US. The observed patterns of obesity-related risk factors and their current and future impact on the burden of cardiovascular diseases remain to be explained.
PMCID: PMC3547948  PMID: 23349785
5.  Indoor Air Pollution and Blood Pressure in Adult Women Living in Rural China 
Environmental Health Perspectives  2011;119(10):1390-1395.
Background: Almost half of the world’s population uses coal and biomass fuels for domestic energy. Limited evidence suggests that exposure to air pollutants from indoor biomass combustion may be associated with elevated blood pressure (BP).
Objective: Our aim was to assess the relationship between air pollution exposure from indoor biomass combustion and BP in women in rural China.
Methods: We measured 24-hr personal integrated gravimetric exposure to fine particles < 2.5 µm in aerodynamic diameter (PM2.5) and systolic BP (SBP) and diastolic BP (DBP) in the winter and summer among 280 women ≥ 25 years of age living in rural households using biomass fuels in Yunnan, China. We investigated the association between PM2.5 exposure and SBP and DBP using mixed-effects models with random intercepts to account for correlation among repeated measures.
Results: Personal average 24-hr exposure to PM2.5 ranged from 22 to 634 µg/m3 in winter and from 9 to 492 µg/m3 in summer. A 1-log-µg/m3 increase in PM2.5 exposure was associated with 2.2 mm Hg higher SBP [95% confidence interval (CI), 0.8 to 3.7; p = 0.003] and 0.5 mm Hg higher DBP (95% CI, –0.4 to 1.3; p = 0.31) among all women; estimated effects varied by age group. Among women > 50 years of age, a 1-log-µg/m3 increase in PM2.5 exposure was associated with 4.1 mm Hg higher SBP (95% CI, 1.5 to 6.6; p = 0.002) and 1.8 mm Hg higher DBP (95% CI, 0.4 to 3.2; p = 0.01). PM2.5 exposure was positively associated with SBP among younger women, but the association was not statistically significant.
Conclusion: PM2.5 exposure from biomass combustion may be a risk factor for elevated BP and hence for cardiovascular events. Our findings should be corroborated in longitudinal studies.
PMCID: PMC3230444  PMID: 21724522
biomass; blood pressure; cardiovascular health; China; household air pollution; indoor air pollution; particulate matter; solid fuels
6.  Effect modification by population dietary folate on the association between MTHFR genotype, homocysteine, and stroke risk: a meta-analysis of genetic studies and randomised trials 
Lancet  2011;378(9791):584-594.
The MTHFR 677C→T polymorphism has been associated with raised homocysteine concentration and increased risk of stroke. A previous overview showed that the effects were greatest in regions with low dietary folate consumption, but differentiation between the effect of folate and small-study bias was difficult. A meta-analysis of randomised trials of homocysteine-lowering interventions showed no reduction in coronary heart disease events or stroke, but the trials were generally set in populations with high folate consumption. We aimed to reduce the effect of small-study bias and investigate whether folate status modifies the association between MTHFR 677C→T and stroke in a genetic analysis and meta-analysis of randomised controlled trials.
We established a collaboration of genetic studies consisting of 237 datasets including 59 995 individuals with data for homocysteine and 20 885 stroke events. We compared the genetic findings with a meta-analysis of 13 randomised trials of homocysteine-lowering treatments and stroke risk (45 549 individuals, 2314 stroke events, 269 transient ischaemic attacks).
The effect of the MTHFR 677C→T variant on homocysteine concentration was larger in low folate regions (Asia; difference between individuals with TT versus CC genotype, 3·12 μmol/L, 95% CI 2·23 to 4·01) than in areas with folate fortification (America, Australia, and New Zealand, high; 0·13 μmol/L, −0·85 to 1·11). The odds ratio (OR) for stroke was also higher in Asia (1·68, 95% CI 1·44 to 1·97) than in America, Australia, and New Zealand, high (1·03, 0·84 to 1·25). Most randomised trials took place in regions with high or increasing population folate concentrations. The summary relative risk (RR) of stroke in trials of homocysteine-lowering interventions (0·94, 95% CI 0·85 to 1·04) was similar to that predicted for the same extent of homocysteine reduction in large genetic studies in populations with similar folate status (predicted RR 1·00, 95% CI 0·90 to 1·11). Although the predicted effect of homocysteine reduction from large genetic studies in low folate regions (Asia) was larger (RR 0·78, 95% CI 0·68 to 0·90), no trial has evaluated the effect of lowering of homocysteine on stroke risk exclusively in a low folate region.
In regions with increasing levels or established policies of population folate supplementation, evidence from genetic studies and randomised trials is concordant in suggesting an absence of benefit from lowering of homocysteine for prevention of stroke. Further large-scale genetic studies of the association between MTHFR 677C→T and stroke in low folate settings are needed to distinguish effect modification by folate from small-study bias. If future randomised trials of homocysteine-lowering interventions for stroke prevention are undertaken, they should take place in regions with low folate consumption.
Full funding sources listed at end of paper (see Acknowledgments).
PMCID: PMC3156981  PMID: 21803414
7.  Association of 25-hydroxyvitamin D with Blood Pressure in Predominantly 25-hydroxyvitamin D Deficient Hispanic and African Americans 
American journal of hypertension  2009;22(8):867-870.
Several observational studies have recently suggested an inverse association of circulating levels of vitamin D with blood pressure. These findings have been based mainly on Caucasian populations; whether this association also exists among Hispanic and African Americans has yet to be definitively determined. This study investigates the association of 25-hydroxyvitamin D (25[OH]D) with blood pressure in Hispanic and African Americans.
The data source for this study is the Insulin Resistance Atherosclerosis Family Study (IRASFS), which consists of Hispanic- and African-American families from three U.S. recruitment centers (n=1334). A variance components model was used to analyze the association of plasma 25[OH]D levels with blood pressure.
An inverse association was found between 25[OH]D and both systolic (β for 10 ng/mL difference= −2.05; p<0.01) and diastolic (β for 10 ng/mL difference= −1.35; p<0.001) blood pressure in all populations combined, after adjusting for age, sex, ethnicity and season of blood draw. Further adjustment for body mass index (BMI) weakened this association (β for 10 ng/mL difference= −0.94; p=0.14 and β for 10 ng/mL difference = −0.64; p=0.09, respectively).
25[OH]D levels are significantly inversely associated with blood pressure in Hispanic and African Americans from the IRASFS. However, this association was not significant after adjustment for BMI. Further research is needed to determine the role of BMI in this association. Large, well-designed prospective studies of the effect of vitamin D supplementation on blood pressure may be warranted.
PMCID: PMC2865679  PMID: 19444222
Vitamin D; 25-hydroxyvitamin D; blood pressure; hypertension; race; ethnic groups; Hispanic; African American
8.  Trends in kidney transplantation rates and disparities. 
OBJECTIVE: To examine the likelihood of transplantation and trends over time among persons with end-stage renal disease (ESRD) in Wisconsin. METHODS: We examined the influence of patient- and community-level characteristics on the rate of kidney transplantation in Wisconsin among 22,387 patients diagnosed with ESRD between January 1, 1982 and October 30, 2005. We grouped patients by the year of ESRD onset in order to model the change in transplantation rates over time. RESULTS: After multivariate adjustment, all other racial groups were significantly less likely to be transplanted compared with whites, and the racial disparity increased over calendar time. Older patients were less likely to be transplanted in all periods. Higher community income and education level and a greater distance from patients' residence to the nearest dialysis center significantly increased the likelihood of transplantation. Males also had a significantly higher rate of transplantation than females. CONCLUSION: These results demonstrate a growing disparity in transplantation rates by demographic characteristics and a consistent disparity in transplantation by socioeconomic characteristics. Future studies should focus on identifying specific barriers to transplantation among different subpopulations in order to target effective interventions.
PMCID: PMC2574300  PMID: 17722672

Results 1-8 (8)