Tracy L. Nelson

Cardiorespiratory fitness and the metabolic syndrome in firefighters

BACKGROUND The leading cause of mortality in on-duty firefighters is sudden cardiac death. While the reason for this remains unclear, low cardiorespiratory fitness and the metabolic syndrome have been associated with increased risk of cardiovascular disease-related events. AIMS To document the levels of cardiorespiratory fitness and the metabolic syndrome, as well as to determine if there is a relationship between these variables, in firefighters. METHODS Maximal cardiorespiratory fitness was assessed using the Bruce treadmill protocol in 214 male firefighters from Colorado. As part of a comprehensive cardiovascular disease risk evaluation, each firefighter was also screened for the metabolic syndrome using the National Cholesterol Education Program/Adult Treatment Panel III (NCEP/ATP III) guidelines. RESULTS At the time of their evaluation, 32 firefighters (15%) met the NCEP/ATP III diagnostic criteria for the metabolic syndrome, and 54 firefighters (25%) failed to achieve a generally accepted minimum cardiorespiratory fitness level of 42.0 ml/kg/min. A significant inverse trend of increasing cardiorespiratory fitness with decreasing metabolic abnormalities was found (P < 0.001). CONCLUSIONS Increased levels of cardiorespiratory fitness are associated with an improved metabolic profile in male firefighters. Comprehensive cardiovascular disease risk factor management and cardiorespiratory fitness improvement are essential for firefighter health and safety.

Impact of improved cookstoves on indoor air pollution and adverse health effects among Honduran women

Elevated indoor air pollution levels due to the burning of biomass in developing countries are well established. Few studies have quantitatively assessed air pollution levels of improved cookstoves and examined these measures in relation to health effects. We conducted a cross-sectional survey among 79 Honduran women cooking with traditional or improved cookstoves. Carbon monoxide and fine particulate matter (PM2.5) levels were assessed via indoor and personal monitoring. Pulmonary function and respiratory symptoms were ascertained. Finger-stick blood spot samples were collected to measure C-reactive protein (CRP) concentrations. The use of improved stoves was associated with 63% lower levels of personal PM2.5, 73% lower levels of indoor PM2.5, and 87% lower levels of indoor carbon monoxide as compared to traditional stoves. Women using traditional stoves reported symptoms more frequently than those using improved stoves. There was no evidence of associations between cookstove type or air quality measures with lung function or CRP.

Egg consumption and risk of type 2 diabetes in older adults

BACKGROUND Type 2 diabetes (T2D) remains an important public health issue in the United States. There are limited and inconsistent data on the association between egg consumption and fasting glucose or incident diabetes. OBJECTIVES We assessed the association between egg intake and incident diabetes in older adults. DESIGN In this prospective study of 3898 men and women from the Cardiovascular Health Study (1989-2007), we assessed egg consumption by using a picture-sorted food questionnaire and ascertained incident T2D annually by using information on hypoglycemic agents and plasma glucose. We used Cox proportional hazards models to estimate adjusted relative risks. RESULTS During a mean follow-up of 11.3 y, 313 new cases of T2D occurred. Crude incidence rates of T2D were 7.39, 6.83, 7.00, 6.72, and 12.20 per 1000 person-years in people who reported egg consumption of never, <1 egg/mo, 1-3 eggs/mo, 1-4 eggs/wk, and almost daily, respectively. In multivariable-adjusted models, there was no association between egg consumption and increased risk of T2D in either sex and overall. In a secondary analysis, dietary cholesterol was not associated with incident diabetes (P for trend = 0.47). In addition, egg consumption was not associated with clinically meaningful differences in fasting glucose, fasting insulin, or measures of insulin resistance despite small absolute analytic differences that were significant. CONCLUSION In this cohort of older adults with limited egg intake, there was no association between egg consumption or dietary cholesterol and increased risk of incident T2D.

Diet and metabolic syndrome.

Given the higher burden of risk factors for metabolic syndrome (MetS) on morbidity and mortality, it is critical to prevent the development of metabolic syndrome in the first place. While dietary habits have been favorably associated with some of the factors included in the definition of metabolic syndrome, limited and inconsistent data have been reported on the role of nutrition in the development of metabolic syndrome. Currently, there is no consensus as to which dietary patterns would confer the lowest risk of MetS. Identification of dietary patterns, food groups, or nutrients that may lower the incidence of metabolic syndrome could improve prevention strategies as well as prognosis among subjects with existing MetS. This manuscript reviews current evidence on dietary patterns, consumption of fat, whole grains, carbohydrate quality and quantity, and moderate alcohol consumption as they relate to metabolic syndrome.

Association of Body Mass Index With Peripheral Arterial Disease in Older Adults The Cardiovascular Health Study

The authors hypothesized that the absence of cross-sectional associations of body mass index (BMI; weight (kg)/height (m)(2)) with peripheral arterial disease (PAD) in prior studies may reflect lower weight among persons who smoke or have poor health status. They conducted an observational study among 5,419 noninstitutionalized residents of 4 US communities aged ≥ 65 years at baseline (1989-1990 or 1992-1993). Ankle brachial index was measured, and participants reported their history of PAD procedures. Participants were followed longitudinally for adjudicated incident PAD events. At baseline, mean BMI was 26.6 (standard deviation, 4.6), and 776 participants (14%) had prevalent PAD. During 13.2 (median) years of follow-up through June 30, 2007, 276 incident PAD events occurred. In cross-sectional analysis, each 5-unit increase in BMI was inversely associated with PAD (prevalence ratio (PR) = 0.92, 95% confidence interval (CI): 0.85, 1.00). However, among persons in good health who had never smoked, the direction of association was opposite (PR = 1.20, 95% CI: 0.94, 1.52). Similar results were observed between BMI calculated using weight at age 50 years and PAD prevalence (PR = 1.30, 95% CI: 1.11, 1.51) and between BMI at baseline and incident PAD events occurring during follow-up (hazard ratio = 1.32, 95% CI: 1.00, 1.76) among never smokers in good health. Greater BMI is associated with PAD in older persons who remain healthy and have never smoked. Normal weight maintenance may decrease PAD incidence and associated comorbidity in older age.

The metabolic syndrome mediates the relationship between cynical hostility and cardiovascular disease.

The objective of this work was to test the clustering of classic Cardiovascular disease (CVD) risk factors, known as the metabolic syndrome (e.g., increased blood pressure, insulin resistance, hypercholesterolemia combined with low levels of high-density lipoprotein, and abdominal fatness), as a mediator of the association between cynicism and CVD. Data were used from the Swedish Adoption/Twin Study of Aging (SATSA) (n = 1944 individuals, average age 62 years, 58% female). The cross-sectional association of cynicism with CVD was significant (standardized β = 0.08, p < .01). In a longitudinal model, cynicism measured in 1984 was associated with CVD measured in 1987 (standardized β = 0.06, p < .01). In a third model, a latent construct “metabolic syndrome” significantly partially mediated this relationship. Cynicism (measured 1984) predicted the metabolic syndrome (measured 1986–1988) (standardized β = 0.20, p < .05) and the metabolic syndrome predicted CVD (measured 1987) (standardized β = 0.18, p < .001); cynicism no longer significantly predicted CVD. Results were adjusted for baseline CVD, smoking, and age. These findings suggest that a clustering of CVD risk factors partially mediate the association between cynicism and CVD in an older population.

Lipoprotein-Associated Phospholipase A2 (Lp-PLA2) and Future Risk of Type 2 Diabetes: Results from the Cardiovascular Health Study

INTRODUCTION Lipoprotein-associated phospholipase A2 (Lp-PLA(2)) has been consistently associated with cardiovascular disease (CVD) risk factors and predictive of CVD outcomes; furthermore, it is consistently higher among type 2 diabetics than nondiabetics. However, the relationships of circulating Lp-PLA(2) mass and activity with incident type 2 diabetes mellitus have not been examined. Therefore, the purpose of this study was to determine the association of Lp-PLA(2) mass and activity with type 2 diabetes among older adults. METHODS We conducted analyses of Lp-PLA(2) and prevalent and incident diabetes among 5474 men and women from the Cardiovascular Health Study (1989-2007). Lp-PLA(2) mass and activity were measured in baseline plasma. Diabetes status was ascertained annually with medication inventories and repeated blood glucose measurements. Generalized linear and Cox proportional hazards models were used to adjust for confounding factors including body mass index and inflammation. RESULTS At baseline, the top two quintiles of Lp-PLA(2) activity were significantly associated with prevalent type 2 diabetes with a multivariable relative risk = 1.35 [95% confidence interval (CI) = 1.11-1.63] for quintile 4, and relative risk = 1.33 (95% CI = 1.07-1.66) for quintile 5. Among participants free of diabetes at baseline, we found a significant positive association with both the homeostatic model assessment for insulin resistance and β-cell function per SD increase in Lp-PLA(2) activity (P values for both <0.01). In prospective analyses, the risk of incident type 2 diabetes was significantly higher among those in the highest quintile of Lp-PLA(2) activity [multivariable hazard ratio = 1.45 (95% CI = 1.01-2.07)] compared with the lowest quintile. Lp-PLA(2) mass was not significantly associated with incident type 2 diabetes. DISCUSSION Lp-PLA(2) activity is positively associated with insulin resistance and predicts incident type 2 diabetes among older adults independent of multiple factors associated with diabetes pathogenesis.

The PPARγ Pro12Ala Polymorphism Is Not Associated with Body Mass Index or Waist Circumference among Hispanics from Colorado

Background/Aims: First to determine if body mass index (BMI) or waist circumference (WC) differ by possession of the Ala allele of the peroxisome proliferator-activated receptor γ (PPARγ) Pro12Ala polymorphism, and second, to determine if dietary fat intake and physical activity moderate these potential relationships among Hispanic Americans from Colorado. Methods: We studied 216 Hispanic pedigrees (1,850 nuclear families) from the San Luis Valley and Denver (mean age 50 years). The families were genotyped for the Pro12Ala polymorphism of the PPARγ gene. BMI, WC and diabetes status were measured in the clinic, and, for diabetics, self-reported BMI at diabetes diagnosis was used. Data were analyzed using the Family-Based Association Test (FBAT). We conducted overall and stratified analyses by tertiles of monounsaturated, polyunsaturated (PUFA) and saturated (SFA) fat intake, the PUFA:SFA ratio, and physical activity. We also used generalized estimating equations (GEE) to further explore the FBAT findings. Results: The average BMI and WC were ∼29 kg/m2 and 101 cm, respectively. The frequency of the Ala allele was 13.5%. We did not find the Ala allele to be associated with BMI or WC overall (p = 0.58 and 0.23, respectively). We did find the Ala allele to be associated with increased BMI in those with high dietary PUFA and PUFA:SFA ratio (p = 0.007 and 0.01, respectively); however, these findings were not confirmed using the GEE models. Conclusions: One previous study has reported the Ala allele to be associated with higher BMI among Hispanics; however, we did not find this association. Further, we could not conclude that dietary fat intake or physical activity altered any association between BMI or WC and the Ala allele.

Lipoprotein-associated phospholipase A2 and future risk of subclinical disease and cardiovascular events in individuals with type 2 diabetes: the Cardiovascular Health Study

Aims/hypothesisType 2 diabetes is an established risk factor for cardiovascular disease (CVD). This increased risk may be due in part to the increased levels of inflammatory factors associated with diabetes. Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a risk marker for CVD and has pro-inflammatory effects in atherosclerotic plaques. We therefore sought to determine whether Lp-PLA2 levels partially explain the greater prevalence of subclinical CVD and greater incidence of CVD outcomes associated with type 2 diabetes in the Cardiovascular Health Study.MethodsWe conducted a cross-sectional and prospective study of 4,062 men and women without previous CVD from the Cardiovascular Health Study (1989 to 2007). Lp-PLA2 mass and activity were measured in baseline plasma. Subclinical disease was determined at baseline and incident CVD was ascertained annually. We used logistic regression for cross-sectional analyses and Cox proportional hazards models for incident analyses.ResultsAt baseline, Lp-PLA2 mass did not differ significantly by type 2 diabetes status; however, Lp-PLA2 activity was significantly higher among type 2 diabetic individuals. Baseline subclinical disease was significantly associated with baseline diabetes and this association was similar in models unadjusted or adjusted for Lp-PLA2 (OR 1.68 [95% CI 1.31–2.15] vs OR 1.67 [95% CI 1.30–2.13]). Baseline type 2 diabetes was also significantly associated with incident CVD events, including fatal CHD, fatal myocardial infarction (MI) and non-fatal MI in multivariable analyses. There were no differences in these estimates after further adjustment for Lp-PLA2 activity.Conclusions/interpretationIn this older cohort, differences in Lp-PLA2 activity did not explain any of the excess risk for subclinical disease or CVD outcomes related to diabetes.

Relationship of abdominal obesity measured by DXA and waist circumference with insulin sensitivity in Hispanic and non‐Hispanic white individuals: The San Luis Valley Diabetes Study

To determine if dual‐energy X‐ray absorptiometry (DXA) measures of trunk fat, a user‐defined abdominal region of interest (ROI) and waist circumference (WC) differ in their association with insulin sensitivity among Hispanics and non‐Hispanic whites (NHW) or explain any ethnic differences in insulin sensitivity.