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Articles by T Keller
Total Records ( 2 ) for T Keller
  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.

  I Zegers , T Keller , W Schreiber , J Sheldon , R Albertini , S Blirup Jensen , M Johnson , S Trapmann , H Emons , G Merlini and H. Schimmel
  BACKGROUND:

The availability of a suitable matrix reference material is essential for standardization of the immunoassays used to measure serum proteins. The earlier serum protein reference material ERM-DA470 (previously called CRM470), certified in 1993, has led to a high degree of harmonization of the measurement results. A new serum protein material has now been prepared and its suitability in term of homogeneity and stability has been verified; after characterization, the material has been certified as ERM-DA470k/IFCC.

METHODS:

We characterized the candidate reference material for 14 proteins by applying a protocol that is considered to be a reference measurement procedure, by use of optimized immunoassays. ERM-DA470 was used as a calibrant.

RESULTS:

For 12 proteins [2 macroglobulin (A2M), 1 acid glycoprotein (orosomucoid, AAG), 1 antitrypsin (1-protease inhibitor, AAT), albumin (ALB), complement 3c (C3c), complement 4 (C4), haptoglobin (HPT), IgA, IgG, IgM, transferrin (TRF), and transthyretin (TTR)], the results allowed assignment of certified values in ERM-DA470k/IFCC. For CRP, we observed a bias between the lyophilized and liquid frozen materials, and for CER, the distribution of values was too broad. Therefore, these 2 proteins were not certified in the ERM-DA470k/IFCC. Different value transfer procedures were tested (open and closed procedures) and found to provide equivalent results.

CONCLUSIONS:

A new serum protein reference material has been produced, and values have been successfully assigned for 12 proteins.

 
 
 
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