Development of a model-based clinical trial simulation platform to optimize the design of clinical trials for Duchenne muscular dystrophy.

Early clinical trials of therapies to treat Duchenne muscular dystrophy (DMD), a fatal genetic X-linked pediatric disease, have been designed based on the limited understanding of natural disease progression and variability in clinical measures over different stages of the continuum of the disease. The objective was to inform the design of DMD clinical trials by developing a disease progression model-based clinical trial simulation (CTS) platform based on measures commonly used in DMD trials. Data were integrated from past studies through the Duchenne Regulatory Science Consortium founded by the Critical Path Institute (15 clinical trials and studies, 1505 subjects, 27,252 observations). Using a nonlinear mixed-effects modeling approach, longitudinal dynamics of five measures were modeled (NorthStar Ambulatory Assessment, forced vital capacity, and the velocities of the following three timed functional tests: time to stand from supine, time to climb 4 stairs, and 10 meter walk-run time). The models were validated on external data sets and captured longitudinal changes in the five measures well, including both early disease when function improves as a result of growth and development and the decline in function in later stages. The models can be used in the CTS platform to perform trial simulations to optimize the selection of inclusion/exclusion criteria, selection of measures, and other trial parameters. The data sets and models have been reviewed by the US Food and Drug Administration and the European Medicines Agency; have been accepted into the Fit-for-Purpose and Qualification for Novel Methodologies pathways, respectively; and will be submitted for potential endorsement by both agencies.

Standardized Data Structures in Rare Diseases: CDISC User Guides for Duchenne Muscular Dystrophy and Huntington's Disease.

Interest in drug development for rare diseases has expanded dramatically since the Orphan Drug Act was passed in 1983, with 40% of new drug approvals in 2019 targeting orphan indications. However, limited quantitative understanding of natural history and disease progression hinders progress and increases the risks associated with rare disease drug development. Use of international data standards can assist in data harmonization and enable data exchange, integration into larger datasets, and a quantitative understanding of disease natural history. The US Food and Drug Administration (FDA) requires the use of Clinical Data Interchange Consortium (CDISC) Standards in new drug submissions to help the agency efficiently and effectively receive, process, review, and archive submissions, as well as to help integrate data to answer research questions. Such databases have been at the core of biomarker qualification efforts and fit-for-purpose models endorsed by the regulators. We describe the development of CDISC therapeutic area user guides for Duchenne muscular dystrophy and Huntington's disease through Critical Path Institute consortia. These guides describe formalized data structures and controlled terminology to map and integrate data from different sources. This will result in increased standardization of data collection and allow integration and comparison of data from multiple studies. Integration of multiple data sets enables a quantitative understanding of disease progression, which can help overcome common challenges in clinical trial design in these and other rare diseases. Ultimately, clinical data standardization will lead to a faster path to regulatory approval of urgently needed new therapies for patients.

Biomarkers of the osteoprotegerin pathway: clinical correlates, subclinical disease, incident cardiovascular disease, and mortality.

OBJECTIVE: Experimental evidence identified the osteoprotegerin (OPG)/receptor activator of nuclear factor-kappaB (RANK)/RANK ligand (RANKL) pathway as a candidate system modulating vascular remodeling and cardiovascular disease (CVD). METHODS AND RESULTS: Serum concentrations of OPG and RANKL were measured in 3250 Framingham Study participants (54% women, 61+/-9 years). During a mean follow-up of 4.6 years, 143 (of 3084 free of CVD at baseline) participants developed a first CVD event, and 235 died. In multivariable models, OPG was associated with increased hazards for incident CVD and mortality (hazard ratio, 1.27; 95% CI, 1.04 to 1.54; and hazard ratio, 1.25; 95% CI, 1.07 to 1.47, per 1-SD increment in log-OPG, respectively). Log-OPG was positively related to multiple CVD risk factors, including age, smoking, diabetes, systolic blood pressure, and prevalent CVD. In a subsample (n=1264), the prevalence of coronary artery calcification, measured by computed tomography, increased nonsignificantly with OPG quartiles. RANKL concentrations displayed inverse associations with multiple CVD risk factors, including smoking, diabetes, and antihypertensive treatment, and were not related to coronary artery calcification or incident CVD or mortality. CONCLUSIONS: Our prospective data reinforce OPG as marker for CVD risk factor burden and predictor for CVD and mortality in the community.

Clinical and echocardiographic correlates of plasma procollagen type III amino-terminal peptide levels in the community.

BACKGROUND: Left ventricular remodeling is characterized by increased collagen deposition in the extracellular matrix. Levels of plasma procollagen type III amino-terminal peptide (PIIINP), a marker of collagen turnover, are elevated in the setting of recent myocardial infarction, heart failure, and cardiomyopathy. Whether plasma PIIINP levels are a useful indicator of subclinical left ventricular abnormalities in ambulatory individuals has not been studied. METHODS: We examined 967 Framingham Heart Study participants (mean age, 56 years; 60% women) who underwent routine echocardiography and measurement of plasma PIIINP levels. All participants were free of prior myocardial infarction or heart failure. Multivariable regression analyses were performed to examine the clinical and echocardiographic correlates of PIIINP levels. RESULTS: Plasma PIIINP levels increased with age and body mass index but did not significantly correlate with other cardiovascular risk factors including hypertension and diabetes. In multivariable models, there was no association between plasma PIIINP levels and left ventricular mass (P = .89), left ventricular fractional shortening (P = .15), left ventricular end-diastolic dimension (P = .51), or left atrial size (P = .68). Plasma PIIINP levels were positively correlated with tissue inhibitor of metalloproteinase-1 levels (multivariable-adjusted, P = .001). CONCLUSIONS: The use of biomarkers of extracellular matrix turnover has generated recent interest, with plasma PIIINP being the most commonly studied biomarker in acute settings. However, our findings in a large, community-based cohort suggest that plasma PIIINP has limited use for the detection of structural heart disease in ambulatory individuals.

Association of multiple inflammatory markers with carotid intimal medial thickness and stenosis (from the Framingham Heart Study).

Inflammatory markers, particularly C-reactive protein (CRP), predict incident cardiovascular disease and are associated with the presence of subclinical atherosclerosis. The relations between multiple inflammatory markers and direct measures of atherosclerosis are less well established. Participants in the Offspring Cohort of the Framingham Heart Study (n = 2,885, 53% women, mean age 59 years) received routine assessments of common carotid artery intima-media thickness (CCA-IMT), internal carotid artery intima-media thickness (ICA-IMT), and the presence or absence of > or =25% carotid stenosis by ultrasonography. Circulating inflammatory markers assessed from an examination 4 years later included CRP, interleukin-6 (IL-6), intercellular adhesion molecule-1, monocyte chemoattractant protein-1, P-selectin, and CD40 ligand. Assessed as a group, inflammatory markers were significantly associated with ICA-IMT (p = 0.01), marginally with carotid stenosis (p = 0.08), but not with CCA-IMT. Individually, with an increase from the 25th to 75th percentile in IL-6, there were significant increases in ICA-IMT and carotid stenosis (for ICA-IMT, estimated fold increase 1.04, 95% confidence interval 1.03 to 1.06, p = 0.0004; for carotid stenosis, odds ratio 1.25, 95% confidence interval 1.06 to 1.47, p = 0.007) after adjustment for age, gender, and established risk factors for atherosclerosis. There was a similar significant multivariate-adjusted association of CRP with ICA-IMT but not with carotid stenosis. Smoking appeared to modify the associations of ICA-IMT with CRP (p = 0.009) and with IL-6 (p = 0.006); the association was more pronounced in current (vs former or never) smokers. In conclusion, there were modest associations of inflammatory markers, particularly IL-6, with carotid atherosclerosis. This association appears more pronounced in current smokers than in former smokers and nonsmokers.

The Third Generation Cohort of the National Heart, Lung, and Blood Institute's Framingham Heart Study: design, recruitment, and initial examination.

For nearly 60 years, the Framingham Heart Study has examined the natural history, risk factors, and prognosis of cardiovascular, lung, and other diseases. Recruitment of the Original Cohort began in 1948. Twenty-three years later, 3,548 children of the Original Cohort, along with 1,576 of their spouses, enrolled in the Offspring Cohort. Beginning in 2002, 4,095 adults having at least one parent in the Offspring Cohort enrolled in the Third Generation Cohort, along with 103 parents of Third Generation Cohort participants who were not previously enrolled in the Offspring Cohort. The objective of new recruitment was to complement phenotypic and genotypic information obtained from prior generations, with priority assigned to larger families. From a pool of 6,553 eligible individuals, 1,912 men and 2,183 women consented and attended the first examination (mean age: 40 (standard deviation: 9) years; range: 19-72 years). The examination included clinical and laboratory assessments of vascular risk factors and imaging for subclinical atherosclerosis, as well as assessment of cardiac structure and function. The comparison of Third Generation Cohort data with measures previously collected from the first two generations will facilitate investigations of genetic and environmental risk factors for subclinical and overt diseases, with a focus on cardiovascular and lung disorders.

Single-gene mutations and increased left ventricular wall thickness in the community: the Framingham Heart Study.

BACKGROUND: Mutations in sarcomere protein, PRKAG2, LAMP2, alpha-galactosidase A (GLA), and several mitochondrial genes can cause rare familial cardiomyopathies, but their contribution to increased left ventricular wall thickness (LVWT) in the community is unknown. METHODS AND RESULTS: We studied 1862 unrelated participants (52% women; age, 59+/-9 years) from the community-based Framingham Heart Study who had echocardiograms and provided DNA samples but did not have severe hypertension, aortic prosthesis, or significant aortic stenosis. Eight sarcomere protein genes, 3 storage cardiomyopathy-causing genes, and 27 mitochondrial genes were sequenced in unrelated individuals with increased LVWT (maximum LVWT >13 mm). Fifty eligible participants (9 women) had unexplained increased LVWT. We detected 8 mutations in 9 individuals (2 women); 7 mutations in 5 sarcomere protein genes (MYH7, MYBPC3, TNNT2, TNNI3, MYL3), and 1 GLA mutation. In individuals with increased LVWT, participants with sarcomere protein and storage mutations were clinically indistinguishable from those without mutations. CONCLUSIONS: In a community-based cohort, about 3% of eligible participants had increased LVWT, of whom 18% had sarcomere protein or lipid storage gene mutations. Increased LVWT in the community is a very heterogeneous condition, which sometimes may arise from single-gene variants in one of a number of genes.

Cross-sectional correlates of serum heat shock protein 70 in the community.

BACKGROUND: Recent studies of referral samples suggest that heat shock proteins play a key role in the pathogenesis of high BP and cardiovascular diseases (CVD) including heart failure. It is unclear whether circulating heat shock protein 70 (HSP70) levels are related to CVD risk factors, echocardiographic indexes of left ventricular (LV) remodeling, and prevalent CVD in the population. METHODS: We evaluated the cross-sectional relations of serum HSP70 to established CVD risk factors (including hypertension), markers of oxidative stress (urinary 8-epi-PGF(2alpha)) and inflammation (plasma interleukin-6, C-reactive protein, monocyte chemoattractant protein-1 MCP-1, and soluble intercellular adhesion molecule sICAM-1), echocardiographic LV dimensions and prevalent CVD in 456 Framingham Offspring Study participants (mean age 61 years, 42% women). RESULTS: In multivariable analyses, serum HSP70 was not associated with age, sex, vascular risk factors (including hypertension), echocardiographic LV mass or prevalent CVD. Also, serum HSP70 was not related to any of the biomarkers evaluated (p> or = 0.10 for all). CONCLUSIONS: In our community-based sample, serum HSP70 was similar in men and women, and not significantly related to traditional or novel risk factors, to LV mass or to prevalent CVD. Our data suggest that blood levels may not adequately reflect the important role of heat shock proteins in prevalent CVD.

Genome scan of systemic biomarkers of vascular inflammation in the Framingham Heart Study: evidence for susceptibility loci on 1q.

Vascular inflammation plays a central role in atherosclerosis and inflammatory biomarkers predict risk of cardiovascular disease (CVD). Thus, finding genes that influence systemic levels of inflammatory biomarkers may provide insights into genetic determinants of vascular inflammation and CVD. We conducted variance-component linkage analyses of blood levels of four biomarkers of vascular inflammation [C-reactive protein (CRP), interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), soluble intercellular adhesion molecule-1 (sICAM-1)] in 304 extended families from the Framingham Heart Study, using data from a 10cM genome scan. We computed p-values by a permutation approach. Heritability estimates ranged from 14% (IL-6) to 44% (MCP-1) after log transforming and adjusting for covariates. Significant linkage to MCP-1 was found on chromosome 1 (LOD=4.27 at 186cM; genome-wide p=0.005), in a region containing inflammatory candidate genes such as SELE, SELP (E- and P-selectin) and CRP. Other linkage peaks with LOD scores >2 were found for MCP-1 on chromosome 1 (LOD=2.04 at 16cM; LOD=2.34 at 70cM) and chromosome 17 (LOD=2.44 at 22cM) and for sICAM-1 on chromosome 1 at 229cM (LOD=2.09) less than 5cM from the interleukin-10 (IL10) gene. Multiple genes on chromosome 1 may influence inflammatory biomarker levels and may have a potential role in development of CVD.

Clinical and genetic correlates of serum aldosterone in the community: the Framingham Heart Study.

BACKGROUND: We investigated the environmental and genetic sources of interindividual variability in serum aldosterone level in a large, community-based sample. METHODS: We examined the relation of serum aldosterone to vascular risk factors, urine sodium, and candidate single nucleotide polymorphisms in 2891 Framingham Offspring Study participants (53.2% women, mean age 59 years) using multivariable linear regression. Multivariable logistic regression was used to identify predictors of high (top quartile) and low (lowest quartile) serum aldosterone values. We estimated heritability of serum aldosterone via variance-component methods and evaluated linkage via a 10-cM-density genome scan. RESULTS: Clinical variables related to higher serum aldosterone level included female sex, diuretic treatment, and a higher total/high density lipoprotein cholesterol ratio. A high urinary sodium excretion, postmenopausal status (without hormone replacement therapy), increased pulse pressure, and prevalent cardiovascular disease were related to lower serum aldosterone values. Urinary sodium was the strongest correlate of serum aldosterone (R2= 10%). Serum aldosterone levels did not differ by genotype in the aldosterone synthase (CYP11B2c.1-344C>T) and the mineralocorticoid receptor (NR3C2c.754A>G) genes. The estimated heritability of serum aldosterone was 0.10. No chromosomal region attained a log-of-the-odds score >1 in multipoint linkage analysis. CONCLUSIONS: We observed a complex relation between serum aldosterone and vascular risk factors. The genetic contribution to serum aldosterone level was modest.

QT interval is a heritable quantitative trait with evidence of linkage to chromosome 3 in a genome-wide linkage analysis: The Framingham Heart Study.

OBJECTIVES: To identify genomic regions linked to QT interval duration in an unselected population. BACKGROUND: QT interval prolongation is associated with increased risk of sudden cardiac death and coronary heart disease and may result from acquired conditions or inherited ion channel defects. The influence of genetic variants on QT interval length in apparently healthy individuals is uncertain. METHODS: We studied subjects from the Framingham Heart Study in whom 12-lead ECGs were available from regular clinic examinations. QT, QT-peak, and RR intervals were measured using digital calipers. A 10-centiMorgan (cM) density genome-wide scan was performed in a subset of the largest families having at least two members with ECG phenotypes (326 families). Variance components methods (Genehunter) were used. RESULTS: Evidence was observed for significant heritability of the QT interval (h(2) 0.35; 95% CI, 0.29-0.41), QT-peak interval (h(2) 0.37; 95% CI, 0.29-0.45), and calculated JT interval (h(2) 0.25; 95% CI, 0.19-0.31). In the genome-wide linkage analysis, we found suggestive evidence for linkage of the QT interval 19 to 48 cM from the tip of the short arm of chromosome 3 (maximum two-point LOD score 3.00, maximum multipoint LOD score 2.71). After fine-mapping with seven microsatellite markers, the peak multipoint LOD score rose to 2.84 at 24.4 cM. The region of linkage contains potassium and sodium channel genes, including the SCN5A gene, which has been implicated in one form of the long QT syndrome and in the Brugada syndrome. CONCLUSIONS: QT and related ECG intervals are heritable traits in a large unselected population. We provide suggestive evidence for a quantitative trait locus on chromosome 3 influencing QT interval duration. Further studies are warranted to identify genes that influence QT interval variation and to determine the role of heritable factors in life-threatening QT prolongation.

Heritability and correlates of intercellular adhesion molecule-1 in the Framingham Offspring Study.

OBJECTIVES: We sought to determine the clinical factors and heritability associated with inflammation measured as circulating levels of soluble-intercellular adhesion molecule-1 (sICAM-1) in a community-based cohort. BACKGROUND: Several prospective studies indicate that circulating sICAM-1 is predictive of future cardiovascular events. However, in some studies this predictive value is lost after multivariable adjustment for traditional cardiovascular disease (CVD) risk factors. We addressed the heritability of sICAM-1 and its relation to CVD risk factors in a community-based cohort. METHODS: We examined 3,295 subjects from the Framingham Heart Study and measured sICAM-1 levels. We then used linear and stepwise multivariable regression to determine predictors or sICAM-1 levels. RESULTS: In age- and gender-adjusted regression models, increased sICAM-1 levels were positively associated with age, total/high-density lipoprotein cholesterol, systolic blood pressure, body mass index (BMI), blood glucose, diabetes, smoking, and prevalent CVD. In stepwise multivariable regression models, sICAM-1 levels remained associated with age, female gender, total/high-density lipoprotein cholesterol ratio, BMI, blood glucose, smoking, and prevalent CVD. The residual heritability of sICAM-1 was 24%. CONCLUSIONS: In addition to prevalent CVD, established CVD risk factors and non-traditional ones such as BMI were associated with systemic inflammation as determined by sICAM-1 levels. There also is significant heritability of sICAM-1, which suggests a genetic component to systemic inflammation.

Genome-wide scan for pulse pressure in the National Heart, Lung and Blood Institute's Framingham Heart Study.

The objective of this study was to assess heritability and identify chromosomal regions showing evidence of linkage to pulse pressure (PP), a simple indicator of proximal conduit vessel stiffness. Blood pressure data were analyzed for 8478 members of the National Heart, Lung and Blood Institute's (NHLBI) Framingham Heart Study. Long-term PP was defined using 2-stage analysis. First, the difference between systolic and diastolic blood pressure was averaged over all qualifying clinic examinations. In the second stage, mean PP was adjusted for mean age, time period of examination, and body mass index by regression analysis. PP values were available for 6421 individuals in 1593 families for heritability estimation and for 2492 individuals in 330 families for linkage analysis. Microsatellite markers covering the genome at 10 cM intervals were typed by the NHLBI Mammalian Genotyping Service; genome scan data were available on 1585 individuals with PP data. Heritability estimates of long-term PP accounting for hypertension treatment and for ignoring treatment were 0.52 and 0.51, respectively. Variance component linkage analysis identified several locations with suggestive evidence of linkage: chromosome 15 at 122 cM (logarithm of odds [LOD]=2.94), chromosome 7 at 71 cM (LOD=2.42), chromosome 5 at 53 cM (LOD=2.03), and chromosome 10 at 81 cM (LOD=1.83) for PP accounting for treatment. LOD scores were slightly lower when ignoring treatment, with the exception of a peak on chromosome 10 at 81 cM (LOD=2.58). In conclusion, we have demonstrated a substantial genetic component to PP and have identified 4 chromosomal regions that may harbor genes influencing vascular stiffness.

Haptoglobin phenotype and prevalent coronary heart disease in the Framingham offspring cohort.

BACKGROUND: The haptoglobin (Hp) locus is polymorphic with two major alleles denoted 1 and 2. Several recent prospective longitudinal studies have demonstrated conflicting results regarding whether there is an increase or decrease in the relative risk of coronary heart disease (CHD) conferred on individuals homozygous for the haptoglobin 1 allele (Hp 1-1). METHODS: We sought to examine the relationship between Hp type and prevalent coronary heart disease in a cross-sectional study from a large community-based cohort, the Framingham Heart Offspring Study (n = 3273). RESULTS: Overall we found no relation between Hp type and CHD prevalence. In secondary analyses we found a different pattern of Hp type and CHD prevalence by diabetes status. In nondiabetics, compared with Hp 1-1, Hp 2-1 (OR 1.71, 95% CI 1.03, 2.83) was associated with excess prevalence of CHD. In contrast in diabetic individuals we observed the opposite pattern; Hp 2-1 (OR 0.49, 95% CI 0.24, 0.99) and Hp 2-2 (OR 0.46, 95% CI 0.22, 0.96) were associated with diminished prevalence of CHD. CONCLUSIONS: These data are consistent with an interaction between Hp type and diabetes in the prevalence of CHD. These findings will need to be confirmed in other cohorts and in longitudinal studies.

Absence of association between polymorphisms in the hemostatic factor pathway genes and carotid intimal medial thickness: the Framingham Heart Study.

BACKGROUND AND PURPOSE: Fibrinogen, plasminogen activator inhibitor-1, and other key proteins in the coagulation cascade have been implicated in the origin of cardiovascular disease. Polymorphisms in genes encoding these proteins have been associated with variability in plasma levels of these proteins. Carotid intimal medial thickness (IMT) is a heritable, quantitative measure of atherosclerosis that is predictive of subsequent myocardial infarction and stroke. We sought to test whether carotid IMT is associated with polymorphisms in several well-characterized genes in the hemostatic factor pathways. METHODS: Here, 867 men and 911 women (mean age, 57 years) in the Framingham offspring cohort underwent B-mode carotid ultrasonography to determine the mean internal (ICA) and common carotid artery (CCA) IMT. Age-, sex-, and multivariable-adjusted linear regression was used to estimate the association of the following variants with log-transformed CCA and ICA IMT: factor V Leiden, factor VII Arg/Gln, fibrinogen HindIII beta-148, plasminogen activator inhibitor-1 4G/5G, and the glycoprotein IIIa Pl(A2) polymorphism. RESULTS: Mean ICA IMT was 0.58 mm; mean CCA IMT was 0.60 mm. There were no differences in ICA or CCA IMT by genotype for any of the candidate genes in unadjusted, age- or sex-adjusted, and multivariable-adjusted models. CONCLUSIONS: There is no evidence for an association between well-studied polymorphisms in the hemostatic factor genes and carotid IMT. Whether other common genetic variants in hemostatic factor genes are associated with subclinical atherosclerosis remains to be determined.

Heritability and genetic linkage of plasma natriuretic peptide levels.

BACKGROUND: Natriuretic peptides play a critical role in the maintenance of salt and water homeostasis and regulation of vascular tone. Thus, interindividual variation in plasma natriuretic peptide levels may contribute to variation in susceptibility to volume overload and hypertension. It is unknown to what extent genetic factors contribute to variation in plasma natriuretic peptide levels. METHODS AND RESULTS: We studied 1914 Framingham Study participants (mean age 57 years, 53% women) who underwent routine echocardiography and testing for plasma N-terminal proatrial natriuretic peptide (N-ANP) and brain natriuretic peptide (BNP). We estimated sex-specific multivariable models and used variance-components methods, implemented in SOLAR (Sequential Oligogenic Linkage Analysis Routines), to estimate heritability. Multipoint linkage analyses were performed using data from a 10-cM-density genome scan. Age, clinical, and echocardiographic variables accounted for 42% and 40% of the variation in log N-ANP and log BNP levels, respectively, in men. Corresponding values in women were 27% and 21%. Multivariable-adjusted heritabilities were 0.44 for log N-ANP and 0.35 for log BNP (P<0.0001). Genome-wide linkage analyses, based on 1142 participants from the 314 largest families, revealed 2 regions of suggestive linkage for log N-ANP and log BNP on chromosomes 2p25 (log-of-odds score 2.40) and 12p13 (log-of-odds score 2.13), respectively. CONCLUSIONS: In this community-based sample, a substantial proportion of the unexplained variation in plasma natriuretic peptide levels was attributable to additive genetic effects. Additional studies using candidate gene approaches may provide insight into the genetic loci that regulate plasma natriuretic peptide levels in humans.

Obesity and systemic oxidative stress: clinical correlates of oxidative stress in the Framingham Study.

OBJECTIVE: To determine the clinical conditions associated with systemic oxidative stress in a community-based cohort. Information regarding cardiovascular risk factors associated with systemic oxidative stress has largely been derived from highly selected samples with advanced stages of vascular disease. Thus, it has been difficult to evaluate the relative contribution of each cardiovascular risk factor to systemic oxidative stress and to determine whether such risk factors act independently and are applicable to the general population. METHODS AND RESULTS: We examined 2828 subjects from the Framingham Heart Study and measured urinary creatinine-indexed levels of 8-epi-PGF2alpha as a marker of systemic oxidative stress. Age- and sex-adjusted multivariable regression models were used to assess clinical correlates of oxidative stress. In age- and sex-adjusted models, increased urinary creatinine-indexed 8-epi-PGF2alpha levels were positively associated with female sex, hypertension treatment, smoking, diabetes, blood glucose, body mass index, and a history of cardiovascular disease. In contrast, age and total cholesterol were negatively correlated with urinary creatinine-indexed 8-epi-PGF2alpha levels. After adjustment for several covariates, decreasing age and total/HDL cholesterol ratio, sex, smoking, body mass index, blood glucose, and cardiovascular disease remained associated with urinary 8-epi-PGF2alpha levels. CONCLUSIONS: Smoking, diabetes, and body mass index were highly associated with systemic oxidative stress as determined by creatinine-indexed urinary 8-epi-PGF2alpha levels. The effect of body mass index was minimally affected by blood glucose, and diabetes and may suggest an important role of oxidative stress in the deleterious impact of obesity on cardiovascular disease.

Genome scan linkage results for heart rate variability (the Framingham Heart Study).

There is a substantial heritable component to the beat-to-beat variation in heart rate. However, the molecular mechanisms underlying the control of heart rate variability (HRV) remain unknown. The present study sought to identify chromosomal regions linked to HRV phenotypes. The first 2 hours of ambulatory electrocardiographic recordings obtained from Framingham Heart Study subjects attending a routine examination were processed for HRV. HRV variables analyzed included very-low-frequency power, low-frequency power, and high-frequency power. Gender-specific residuals were used for log-transformed HRV data after adjustment for age, HR, systolic and diastolic blood pressures, and coffee and alcohol consumption. In conjunction with a 10-cM genome-wide scan, HRV data were available for 725 subjects in 230 extended families, including 390 sibling pairs. Variance component log-of-the-odds (LOD) scores were obtained. The highest multipoint LOD scores were obtained for log very-low frequency on chromosome 15 at 62 cM (LOD 1.84) and for log low frequency on chromosome 2 at 153 cM (LOD 1.81). These data suggest there may be influential genetic regions contributing to HRV. Further studies are warranted to identify genes in these regions that may influence autonomic tone. Recognition of the genetic determinants of HRV may provide additional insights into the pathophysiology of the autonomic nervous system and offer clues to its modulation.