Publications

251 Publications visible to you, out of a total of 251

Abstract (Expand)

BACKGROUND & AIM: The association of circulating sphingosine-1-phosphate (S1P), a bioactive lipid involved in various cellular processes, and related metabolites such as sphinganine-1-phosphate (SA1P) and sphingosine (SPH) with mortality in patients with end-stage liver disease is investigated in the presented study. S1P as a bioactive lipid mediator, is involved in several cellular processes, however, in end-stage liver disease its role is not understood. METHODS: The study cohort consisted of 95 patients with end-stage liver disease and available information on one-year outcome. The median MELD (Model for end-stage liver disease) score was 12.41 (Range 6.43-39.63). The quantification of sphingolipids in citrated plasma specimen was performed after methanolic protein precipitation followed by hydrophilic interaction liquid chromatography and tandem mass spectrometric detection. RESULTS: S1P and SA1P displayed significant correlations with the MELD score. Patients with circulating S1P levels below the lowest tertile (110.68 ng/ml) showed the poorest one-year survival rate of only 57.1%, whereas one-year survival rate in patients with S1P plasma levels above 165.67 ng/ml was 93.8%. In a multivariate cox regression analysis including platelet counts, concentrations of hemoglobin and MELD score, S1P remained a significant predictor for three-month and one-year mortality. CONCLUSIONS: Low plasma S1P concentrations are highly significantly associated with prognosis in end-stage liver disease. This association is independent of the stage of liver disease. Further studies should be performed to investigate S1P, its role in the pathophysiology of liver diseases and its potential for therapeutic interventions.

Authors: Susen Becker, Benedict Kinny-Koster, Michael Bartels, Markus Scholz, Daniel Seehofer, Thomas Berg, Cornelius Engelmann, Joachim Thiery, Uta Ceglarek, Thorsten Kaiser

Date Published: 23rd Mar 2017

Publication Type: Journal article

Abstract (Expand)

Conditional power of survival endpoints at interim analyses can support decisions on continuing a trial or stopping it for futility. When a cure fraction becomes apparent, conditional power cannot be calculated accurately using simple survival models, e.g. the exponential model. Non-mixture models consider such cure fractions. In this paper, we derive conditional power functions for non-mixture models, namely the non-mixture exponential, the non-mixture Weibull, and the non-mixture Gamma models. Formulae were implemented in the R package CP. For an example data set of a clinical trial, we calculated conditional power under the non-mixture models and compared results with those under the simple exponential model.

Authors: A. Kuehnapfel, F. Schwarzenberger, M. Scholz

Date Published: 17th Mar 2017

Publication Type: Journal article

Abstract (Expand)

BACKGROUND AND AIMS: Carotid artery plaque is an established marker of subclinical atherosclerosis and common patho-mechanisms with coronary artery disease (CAD) are hypothesized. We aimed to identify genetic variants associated with carotid plaque and to examine the potential shared genetic basis with CAD. METHODS: After investigating the reliability of plaque detection, we performed a genome-wide meta-association study in two independent cohorts (LIFE-Adult, n = 4037 and LIFE-Heart, n = 3152) for carotid plaque score (PS), defined as the sum of the plaque load of common carotid artery and carotid bulb. Further, we analyzed whether previously reported CAD and stroke loci were also associated with PS. RESULTS: We identified two loci with genome-wide significance for PS. One locus is the known CAD-locus at chromosome 9p21 (lead SNP rs9644862, p = 8.73 x 10(-12)). We also describe a novel locus on chromosome 10q24 within the SFXN2 gene as the most probable candidate (lead SNP rs2902548, p = 1.97 x 10(-8)). In addition, 17 out of 58 known CAD loci and six of 17 known stroke loci were associated with PS at a nominal level of significance. CONCLUSIONS: We showed that PS is a reliable trait to analyze genetics of atherosclerosis. Two new loci of genome-wide significant association with PS were found. The observed non-random overlap of CAD and PS associations strengthens the hypothesis of a shared genetic basis for these atherosclerotic manifestations.

Authors: J. Pott, R. Burkhardt, F. Beutner, K. Horn, A. Teren, H. Kirsten, L. M. Holdt, G. Schuler, D. Teupser, M. Loeffler, J. Thiery, M. Scholz

Date Published: 11th Mar 2017

Publication Type: Journal article

Human Diseases: atherosclerosis

Abstract (Expand)

PURPOSE Body surface area is a physiological quantity relevant for many medical applications. In clinical practice, it is determined by empirical formulae. 3D laser-based anthropometry provides an easyy and effective way to measure body surface area but is not ubiquitously available. We used data from laser-based anthropometry from a population-based study to assess validity of published and commonly used empirical formulae. METHODS We performed a large population-based study on adults collecting classical anthropometric measurements and 3D body surface assessments (N = 1435). We determined reliability of the 3D body surface assessment and validity of 18 different empirical formulae proposed in the literature. The performance of these formulae is studied in subsets of sex and BMI. Finally, improvements of parameter settings of formulae and adjustments for sex and BMI were considered. RESULTS 3D body surface measurements show excellent intra- and inter-rater reliability of 0.998 (overall concordance correlation coefficient, OCCC was used as measure of agreement). Empirical formulae of Fujimoto and Watanabe, Shuter and Aslani and Sendroy and Cecchini performed best with excellent concordance with OCCC \textgreater 0.949 even in subgroups of sex and BMI. Re-parametrization of formulae and adjustment for sex and BMI slightly improved results. CONCLUSION In adults, 3D laser-based body surface assessment is a reliable alternative to estimation by empirical formulae. However, there are empirical formulae showing excellent results even in subgroups of sex and BMI with only little room for improvement.

Authors: Andreas Kuehnapfel, Peter Ahnert, Markus Loeffler, Markus Scholz

Date Published: 27th Jan 2017

Publication Type: Journal article

Abstract (Expand)

BACKGROUND Few data exist on adverse drug reactions (ADR) in elderly people. In this group, pharmacotherapy represents a challenge with regard to comorbidities, drug interactions and compliance. OBJECTIVEVE The aim of this article is to highlight the characteristics of ADR in elderly patients. METHODS In addition to a literature review we present the first data from the Leipzig Research Center for Civilization Diseases (LIFE). Between 2011 and 2015 a total of 9537 subjects aged 40-79 years were randomly included in this population-based, age and sex standardized investigation in the inhabitants of Leipzig, Germany and special emphasis was placed on allergies including questions with regard to ADR. RESULTS Of the 9537 subjects, data on allergies were available from 8979 subjects. Female gender, comorbidities and the use of multiple drugs were significantly associated with an increased risk of ADR. Women also reported ADR significantly more frequently than men. Of the subjects 22% reported suffering from some form of ADR as a result of medications, while in 2.3% this reaction had occurred within the previous 12 months. Less than 15% of LIFE patients with ADR were in possession of a document giving details of the ADR. DISCUSSION The occurrence of ADR significantly contributes to morbidity in elderly patients. For prevention of ADR knowledge of patient-related factors, underlying diseases, drug characteristics and drug interactions are necessary.

Authors: R. Treudler, F. Walther, P. Ahnert, J-C Simon

Date Published: 2017

Publication Type: Journal article

Abstract (Expand)

BACKGROUND Community acquired pneumonia (CAP) is a high incidence disease resulting in about 260,000 hospital admissions per year in Germany, more than myocardial infarction or stroke. Worldwide, CAPP is the most frequent infectious disease with high lethality ranging from 1.2 % in those 20-29 years old to over 10 % in patients older than 70 years, even in industrial nations. CAP poses numerous medical challenges, which the PROGRESS (Pneumonia Research Network on Genetic Resistance and Susceptibility for the Evolution of Severe Sepsis) network aims to tackle: Operationalization of disease severity throughout the course of disease, outcome prediction for hospitalized patients and prediction of transitions from uncomplicated CAP to severe CAP, and finally, to CAP with sepsis and organ failure as a life-threatening condition. It is a major aim of PROGRESS to understand and predict patient heterogeneity regarding outcome in the hospital and to develop novel treatment concepts. METHODS PROGRESS was designed as a clinical, observational, multi-center study of patients with CAP requiring hospitalization. More than 1600 patients selected for low burden of co-morbidities have been enrolled, aiming at a total of 3000. Course of disease, along with therapy, was closely monitored by daily assessments and long-term follow-up. Daily blood samples allow in depth molecular-genetic characterization of patients. We established a well-organized workflow for sample logistics and a comprehensive data management system to collect and manage data from more than 50 study centers in Germany and Austria. Samples are stored in a central biobank and clinical data are stored in a central data base which also integrates all data from molecular assessments. DISCUSSION With the PROGRESS study, we established a comprehensive data base of high quality clinical and molecular data allowing investigation of pressing research questions regarding CAP. In-depth molecular characterization will contribute to the discovery of disease mechanisms and establishment of diagnostic and predictive biomarkers. A strength of PROGRESS is the focus on younger patients with low burden of co-morbidities, allowing a more direct look at host biology with less confounding. As a resulting limitation, insights from PROGRESS will require validation in representative patient cohorts to assess clinical utility. TRIAL REGISTRATION The PROGRESS study was retrospectively registered on May 24(th), 2016 with ClinicalTrials.gov: NCT02782013.

Authors: Peter Ahnert, Petra Creutz, Markus Scholz, Hartwig Schütte, Christoph Engel, Hamid Hossain, Trinad Chakraborty, Michael Bauer, Michael Kiehntopf, Uwe Völker, Sven Hammerschmidt, Markus Loeffler, Norbert Suttorp

Date Published: 1st Dec 2016

Publication Type: Journal article

Abstract (Expand)

A variety of modern software packages are available for genotype imputation relying on advanced concepts such as pre-phasing of the target dataset or utilization of admixed reference panels. In this study, we performed a comprehensive evaluation of the accuracy of modern imputation methods on the basis of the publicly available POPRES samples. Good quality genotypes were masked and re-imputed by different imputation frameworks: namely MaCH, IMPUTE2, MaCH-Minimac, SHAPEIT-IMPUTE2 and MaCH-Admix. Results were compared to evaluate the relative merit of pre-phasing and the usage of admixed references. We showed that the pre-phasing framework SHAPEIT-IMPUTE2 can overestimate the certainty of genotype distributions resulting in the lowest percentage of correctly imputed genotypes in our case. MaCH-Minimac performed better than SHAPEIT-IMPUTE2. Pre-phasing always reduced imputation accuracy. IMPUTE2 and MaCH-Admix, both relying on admixed-reference panels, showed comparable results. MaCH showed superior results if well-matched references were available (Nei’s GST ≤ 0.010). For small to medium datasets, frameworks using genetically closest reference panel are recommended if the genetic distance between target and reference data set is small. Our results are valid for small to medium data sets. As shown on a larger data set of population based German samples, the disadvantage of pre-phasing decreases for larger sample sizes.

Authors: Nab Raj Roshyara, Katrin Horn, Holger Kirsten, Peter Ahnert, Markus Scholz

Date Published: 1st Dec 2016

Publication Type: Journal article

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