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Articles by T Zeller
Total Records ( 3 ) for T Zeller
  M Kohlhaas , T Liu , A Knopp , T Zeller , M. F Ong , M Bohm , B O'Rourke and C. Maack
 

Background— Oxidative stress is causally linked to the progression of heart failure, and mitochondria are critical sources of reactive oxygen species in failing myocardium. We previously observed that in heart failure, elevated cytosolic Na+ ([Na+]i) reduces mitochondrial Ca2+ ([Ca2+]m) by accelerating Ca2+ efflux via the mitochondrial Na+/Ca2+ exchanger. Because the regeneration of antioxidative enzymes requires NADPH, which is indirectly regenerated by the Krebs cycle, and Krebs cycle dehydrogenases are activated by [Ca2+]m, we speculated that in failing myocytes, elevated [Na+]i promotes oxidative stress.

Methods and Results— We used a patch-clamp–based approach to simultaneously monitor cytosolic and mitochondrial Ca2+ and, alternatively, mitochondrial H2O2 together with NAD(P)H in guinea pig cardiac myocytes. Cells were depolarized in a voltage-clamp mode (3 Hz), and a transition of workload was induced by β-adrenergic stimulation. During this transition, NAD(P)H initially oxidized but recovered when [Ca2+]m increased. The transient oxidation of NAD(P)H was closely associated with an increase in mitochondrial H2O2 formation. This reactive oxygen species formation was potentiated when mitochondrial Ca2+ uptake was blocked (by Ru360) or Ca2+ efflux was accelerated (by elevation of [Na+]i). In failing myocytes, H2O2 formation was increased, which was prevented by reducing mitochondrial Ca2+ efflux via the mitochondrial Na+/Ca2+ exchanger.

Conclusions— Besides matching energy supply and demand, mitochondrial Ca2+ uptake critically regulates mitochondrial reactive oxygen species production. In heart failure, elevated [Na+]i promotes reactive oxygen species formation by reducing mitochondrial Ca2+ uptake. This novel mechanism, by which defects in ion homeostasis induce oxidative stress, represents a potential drug target to reduce reactive oxygen species production in the failing heart.

  R. B Schnabel , K. L Lunetta , M. G Larson , J Dupuis , I Lipinska , J Rong , M. H Chen , Z Zhao , J. F Yamamoto , J. B Meigs , V Nicaud , C Perret , T Zeller , S Blankenberg , L Tiret , J. F Keaney , R. S Vasan and E. J. Benjamin
 

Background— Environmental and genetic correlates of inflammatory marker variability are incompletely understood. In the family-based Framingham Heart Study, we investigated heritability and candidate gene associations of systemic inflammatory biomarkers.

Methods and Results— In offspring participants (n=3710), we examined 11 inflammatory biomarkers (CD40 ligand, C-reactive protein, intercellular adhesion molecule-1, interleukin-6, urinary isoprostanes, monocyte chemoattractant protein-1, myeloperoxidase, P-selectin, tumor necrosis factor-, tumor necrosis factor receptor II, fibrinogen). Heritability and bivariate genetic and environmental correlations were assessed by Sequential Oligogenic Linkage Analysis routines in 1012 family members. We examined 1943 tagging single-nucleotide polymorphisms in 233 inflammatory pathway genes with ≥5 minor allele carriers using a general genetic linear model. Clinical correlates explained 2.4% (CD40 ligand) to 28.5% (C-reactive protein) of the variability in inflammatory biomarkers. Estimated heritability ranged from 10.9% (isoprostanes) to 44.8% (P-selectin). Most correlations between biomarkers were weak although statistically significant. A total of 45 single-nucleotide polymorphism-biomarker associations met the q-value threshold of 0.25. Novel top single-nucleotide polymorphisms were observed in ICAM1 gene in relation to intercellular adhesion molecule-1 concentrations (rs1799969, P=1.32x10–8) and MPO in relation to myeloperoxidase (rs28730837, P=1.9x10–5). Lowest P values for trans-acting single-nucleotide polymorphisms were observed for APCS with monocyte chemoattractant protein-1 concentrations (rs1374486, P=1.01x10–7) and confirmed for IL6R with interleukin-6 concentrations (rs8192284, P=3.36x10–5). Novel potential candidates (APCS, MPO) need to be replicated.

Conclusions— Our community-based data support the relevance of clinical and genetic factors for explaining variation in inflammatory biomarker traits.

  P. S Wild , C. R Sinning , A Roth , S Wilde , R. B Schnabel , E Lubos , T Zeller , T Keller , K. J Lackner , M Blettner , R. S Vasan , T Munzel and S. Blankenberg
  Background—

Echocardiography, the dominant imaging modality for quantification of left ventricular metrics, has undergone continuing development in the past few decades. However, given the lack of population-based data, current guidelines are still based on restricted and small data sets analyzed with methods including expert opinion. This work presents empirically derived reference values from a large-scale, epidemiologic study conducted with state-of-the-art imaging technology and methods.

Methods and Results—

The distribution of echocardiographic measurements of the left ventricle was analyzed in a population-based sample of 5000 mid-Europeans from the Gutenberg Heart Study in Germany. The randomly selected, noninstitutionalized sample provides data on apparently healthy individuals, as well as on those with prevalent disease. Standardized echocardiograms were recorded in a comprehensive data set at a single site with centralized training and certification of sonographers. Sex-specific reference limits and categories indicating the grade of deviation from the reference were calculated, and nomograms were created by quantile regression. Detailed information is given on the association between left ventricular geometry and age.

Conclusions—

The rapidly evolving echocardiographic technology with persistent improvements in image quality and new measurement conventions require the evaluation of new reference limits for left ventricular metrics. The present investigation formulates reference limits and nomograms from state-of-the-art technology and methods based on a large population-based data set. The distribution of echocardiographic measures of left ventricular geometry presents, in part, nonlinear associations with age, which should be the subject of future investigations.

 
 
 
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