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U Broeckel

Publications and source records attributed to U Broeckel.

8 recordsLinked to original sources
PubMed2005

Quantitative founder-effect analysis of French Canadian families identifies specific loci contributing to metabolic phenotypes of hypertension.

The Saguenay-Lac St-Jean population of Quebec is relatively isolated and has genealogical records dating to the 17th-century French founders. In 120 extended families with at least one sib pair affected with early-onset hypertension and/or dyslipidemia, we analyzed the genetic determinants of hypertension and related cardiovascular and metabolic conditions. Variance-components linkage analysis revealed 46 loci after 100,000 permutations. The most prominent clusters of overlapping quantitative-trait loci were on chromosomes 1 and 3, a finding supported by principal-components and bivariate analyses. These genetic determinants were further tested by classifying families by use of LOD score density analysis for each measured phenotype at every 5 cM. Our study showed the founder effect over several generations and classes of living individuals. This quantitative genealogical approach supports the notion of the ancestral causality of traits uniquely present and inherited in distinct family classes. With the founder effect, traits determined within population subsets are measurably and quantitatively transmitted through generational lineage, with a precise component contributing to phenotypic variance. These methods should accelerate the uncovering of causal haplotypes in complex diseases such as hypertension and metabolic syndrome.

Adolescent↗
PubMed2003

Prevalence of left ventricular diastolic dysfunction in the community. Results from a Doppler echocardiographic-based survey of a population sample.

AIMS: The prevalence of left ventricular diastolic abnormalities in the general population is largely unclear. Thus, the aim of this study was, firstly, to identify abnormal diastolic function by echocardiography in an age-stratified population-based European sample (MONICA Augsburg, n=1274, 25 to 75 years, mean 51+/-14) and, secondly, to analyse clinical and anthropometric parameters associated with diastolic abnormalities. METHODS AND RESULTS: The overall prevalence of diastolic abnormalities, as defined by the European Study Group on Diastolic Heart Failure (i.e. age dependent isovolumic relaxation time (92-105 ms) and early (E-wave) and late (A-wave) left ventricular filling (E/A-ratio, 1-0.5)) was 11.1%. When only subjects treated with diuretics or with left atrial enlargement were considered (suggesting diastolic dysfunction) the prevalence was 3.1%. The prevalence of diastolic abnormalities varied according to age: from 2.8% in individuals aged 25-35 years to 15.8% among those older than 65 years (P<0.01). Significantly higher rates of diastolic abnormalities were observed in men as compared to women (13.8% vs 8.6%, P<0.01). Independent predictors of diastolic abnormalities were arterial hypertension, evidence of left ventricular (LV) hypertrophy, and coronary artery disease. Interestingly, in the absence of these predisposing conditions, diastolic abnormalities (4.3%) or diastolic dysfunction (1.1%) were rare, even in subjects older than 50 years of age (4.6%) and (1.2%), respectively. In addition to these factors, diastolic dysfunction was related to high body mass index, high body fat mass, and diabetes mellitus. CONCLUSION: The prevalences of diastolic abnormalities and diastolic dysfunction are higher than that of systolic dysfunction and are increased (despite age-dependent diagnostic criteria) in the elderly. However, in the absence of risk factors for diastolic abnormalities or diastolic dysfunction, namely LV hypertrophy, arterial hypertension, coronary artery disease, obesity and diabetes the condition is rare even in elderly subjects. These data allow speculation on whether diastolic heart failure may be prevented by improved implementation of measures directed against predisposing conditions.

Adult↗
PubMed2001

The future of genetic case-control studies.

The case-control study design has been a veritable workhorse in epidemiological research since its inception and acceptance as a valid and valued field of inquiry. The reasons for this owe to the simplicity of the required sampling and the (potential) ease of analysis and interpretation of results. Unfortunately, there are a number of problems that plague the use of the case-control design in assessing relationships between genetic variation and disease susceptibility in the population at large. Many of these problems are entirely analogous to problems that inhere in applications of the case-control design in nongenetic settings. These problems include stratification, the assessment of statistical significance, heterogeneity, and the interpretation of multiple outcomes or phenotypic information. In this chapter we describe 10 problems thought to plague genetic case-control studies and offer potential solutions to each. Many of our proposed solutions require the use of multiple DNA markers to accommodate the genetic background of the individuals sampled as cases and controls. It is hoped that our discussions and proposals will spark further debate about the analysis and ultimate utility of the case-control study in genetic epidemiology research.

Case-Control Studies↗
PubMed2000

Localization of a small genomic region associated with elevated ACE.

Defining the relationship between multiple polymorphisms in a small genomic region and an underlying quantitative trait locus (QTL) represents a major challenge in human genetics. Pedigree analyses have shown that angiotensin I-converting enzyme (ACE) levels are influenced by a QTL located within or close to the ACE gene and most likely resides in the 3' region of this locus. We genotyped seven polymorphisms spanning 13 kb in the 3' end of ACE in 159 Afro-Caribbean subjects to evaluate the linkage disequilibrium between these sites and to narrow the genomic region associated with an elevated ACE level using a cladistic analysis. The linkage disequilibrium measurement D' and a haplotype tree revealed three distinct haplotype segments, presumably because of recombination. The value of the linkage disequilibrium parameter p(excess) was highest for site 22982, which is located in the middle segment. A series of nested, cladistic analyses confirmed that the other two regions are unlikely to be the ACE-linked QTL and that the variant resides in the middle region. Analyses of the same polymorphisms in 98 unrelated Europeans in the Monitoring Trends and Determinants in Cardiovascular Diseases (MONICA) study resulted in fewer haplotypes than were observed among the Afro-Caribbean subjects, suggesting that populations with greater genetic diversity may be especially informative for fine-scale mapping.

Black People↗
PubMed1999

Lack of association between a polymorphism of the aldosterone synthase gene and left ventricular structure.

BACKGROUND: Cardiac growth and function may be modulated in part by trophic effects of neurohormones. Specifically, aldosterone has been shown to stimulate the growth of cardiac myocytes and the accumulation of cardiac extracellular matrix proteins. Moreover, a variant of the aldosterone synthase gene (a cytosine/thymidine exchange at position -344 in the transcriptional regulatory region) has been associated with enlargement and disturbed filling of the left ventricle (LV) in a small sample of young white adults. The aim of the present study was to reinvestigate the implications of aldosterone synthase -344C/T allele status for serum aldosterone levels, blood pressure, and LV structure and function in large population-based samples. METHODS AND RESULTS: Individuals who participated in the echocardiographic substudy of the third MONICA (MONitoring trends and determinants in CArdiovascular disease) survey (n=1445) or in the second follow-up of the first MONICA survey (n=562) were studied by standardized anthropometric, echocardiographic, and biochemical measurements as well as genotyping for aldosterone synthase -344C/T allele status. In both surveys, the distribution of sex, age, arterial blood pressure, and body mass index was homogeneous in the aldosterone synthase genotype groups. Echocardiographic LV wall thicknesses, dimensions, and mass indexes were not significantly associated with a specific aldosterone synthase genotype. Likewise, no association was detectable with echocardiographic measures of LV systolic or diastolic function. Data were consistent in both samples and not materially different in subgroups defined by age, sex, or intake of antihypertensive medication. Finally, no significant association was observed for aldosterone synthase allele status and serum aldosterone levels in the group of 562 individuals. CONCLUSIONS: The data are not in favor of a significant contribution of the C/T exchange at position -344 in the aldosterone synthase transcriptional regulatory region to the variability of serum aldosterone levels, blood pressure, or cardiac size or function as found in 2 white population-based samples.

Adult↗
PubMed1998

The associations of body size and body composition with left ventricular mass: impacts for indexation in adults.

OBJECTIVES: We investigated the relationship between body size, body composition and left ventricular mass (LVM) in adults, and assessed the impact of different indexations of LVM on its associations with gender, adiposity and blood pressure. BACKGROUND: The best way to normalize LVM for body size to appropriately distinguish physiologic adaptation from morbid heart morphology was discussed. METHODS: We undertook a community survey of 653 men and 718 women, aged 25 to 74 years. Lean body mass (LBM) was determined by bioelectric impedance analyses and LVM was assessed by two-dimensional guided M-mode echocardiography. RESULTS: After traditional indexations to body height, body height2.7, or body surface area, men had higher LVM than women (p < 0.001). These gender differences disappeared (p > 0.05) when LVM was indexed to LBM. The type of indexation also modified the strength of the association between adiposity and LVM. The estimated impact of body fat on LVM indexed to LBM was less than half that obtained with traditional indexations. In contrast, the magnitude of the associations of blood pressure with LVM was entirely independent of the type of indexation. CONCLUSIONS: This study showed the prominent influence of body composition on adult heart size. Indexation for LBM removed gender differences for LVM and reduced the impact of adiposity, but left the effects of blood pressure unchanged. We suggest that this approach be used for clinical and research applications.

Adaptation, Physiological↗