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188 Publications visible to you, out of a total of 188
Impact of first- and second-line treatment for Hodgkin’s lymphoma on the incidence of AML/MDS and NHL–experience of the German Hodgkin’s Lymphoma Study Group analyzed by a parametric model of carcinogenesis
Genetical Statistics and Systems Biology

Abstract (Expand)

BACKGROUND\backslashr\backslashnUsing a parametric carcinogenesis model, we disentangle the superimposing effects of primary and relapse therapies of Hodgkin’s disease on secondary … neoplasias.\backslashr\backslashnPATIENTS AND METHODS\backslashr\backslashnWe analyze eight randomized trials of the German Hodgkin’s lymphoma study group [5357 individuals, 67 secondary acute myeloid leukemia (AML)/myelodysplastic syndrome (MDS) and 97 secondary non-Hodgkin’s lymphoma (NHL)]. Primary therapies were divided into four groups: radiotherapy alone, moderately dosed COPP/ABVD-like chemotherapies for intermediate and advanced stages and BEACOPP escalated.\backslashr\backslashnRESULTS\backslashr\backslashnFor secondary AML/MDS, the hazards after primary therapies are proportional (maximum at 3.4 years), while the hazard after relapse therapy is more peaked (maximum at 1.8 years). Intermediate and advanced stage chemotherapy resulted in a cumulative risk of 1.5%, while the risk after BEACOPP escalated is higher (4.4%, P = 0.004) and comparable with that after relapse therapy (4.5%). For secondary NHL, there are no differences in cumulative risk between the primary therapies (2.9%), while the risk after relapse therapy is increased (6.6%, P = 0.002).\backslashr\backslashnCONCLUSIONS\backslashr\backslashnBEACOPP escalated moderately increases the risk of secondary AML/MDS but not NHL. No differences were found between other chemotherapies of advanced stages and intermediate stages. Secondary AML/MDS occurs faster after relapse treatment than after primary treatment.

Authors: Markus Scholz, A. Engert, J. Franklin, A. Josting, V. Diehl, Dirk Hasenclever, Markus Loeffler

Date Published: 1st Mar 2011

Publication Type: Journal article

Population-genetic comparison of the Sorbian isolate population in Germany with the German KORA population using genome-wide SNP arrays
Genetical Statistics and Systems Biology

Abstract (Expand)

BACKGROUND\backslashr\backslashnThe Sorbs are an ethnic minority in Germany with putative genetic isolation, making the population interesting for disease mapping. A sample of N = 977 Sorbs is currently … analysed in several genome-wide meta-analyses. Since genetic differences between populations are a major confounding factor in genetic meta-analyses, we compare the Sorbs with the German outbred population of the KORA F3 study (N = 1644) and other publically available European HapMap populations by population genetic means. We also aim to separate effects of over-sampling of families in the Sorbs sample from effects of genetic isolation and compare the power of genetic association studies between the samples.\backslashr\backslashnRESULTS\backslashr\backslashnThe degree of relatedness was significantly higher in the Sorbs. Principal components analysis revealed a west to east clustering of KORA individuals born in Germany, KORA individuals born in Poland or Czech Republic, Half-Sorbs (less than four Sorbian grandparents) and Full-Sorbs. The Sorbs cluster is nearest to the cluster of KORA individuals born in Poland. The number of rare SNPs is significantly higher in the Sorbs sample. FST between KORA and Sorbs is an order of magnitude higher than between different regions in Germany. Compared to the other populations, Sorbs show a higher proportion of individuals with runs of homozygosity between 2.5 Mb and 5 Mb. Linkage disequilibrium (LD) at longer range is also slightly increased but this has no effect on the power of association studies. Oversampling of families in the Sorbs sample causes detectable bias regarding higher FST values and higher LD but the effect is an order of magnitude smaller than the observed differences between KORA and Sorbs. Relatedness in the Sorbs also influenced the power of uncorrected association analyses.\backslashr\backslashnCONCLUSIONS\backslashr\backslashnSorbs show signs of genetic isolation which cannot be explained by over-sampling of relatives, but the effects are moderate in size. The Slavonic origin of the Sorbs is still genetically detectable. Regarding LD structure, a clear advantage for genome-wide association studies cannot be deduced. The significant amount of cryptic relatedness in the Sorbs sample results in inflated variances of Beta-estimators which should be considered in genetic association analyses. BACKGROUND The Sorbs are an ethnic minority in Germany with putative genetic isolation, making the population interesting for disease mapping. A sample of N = 977 Sorbs is currently analysed in several genome-wide meta-analyses. Since genetic differences between populations are a major confounding factor in genetic meta-analyses, we compare the Sorbs with the German outbred population of the KORA F3 study (N = 1644) and other publically available European HapMap populations by population genetic means. We also aim to separate effects of over-sampling of families in the Sorbs sample from effects of genetic isolation and compare the power of genetic association studies between the samples. RESULTS The degree of relatedness was significantly higher in the Sorbs. Principal components analysis revealed a west to east clustering of KORA individuals born in Germany, KORA individuals born in Poland or Czech Republic, Half-Sorbs (less than four Sorbian grandparents) and Full-Sorbs. The Sorbs cluster is nearest to the cluster of KORA individuals born in Poland. The number of rare SNPs is significantly higher in the Sorbs sample. FST between KORA and Sorbs is an order of magnitude higher than between different regions in Germany. Compared to the other populations, Sorbs show a higher proportion of individuals with runs of homozygosity between 2.5 Mb and 5 Mb. Linkage disequilibrium (LD) at longer range is also slightly increased but this has no effect on the power of association studies. Oversampling of families in the Sorbs sample causes detectable bias regarding higher FST values and higher LD but the effect is an order of magnitude smaller than the observed differences between KORA and Sorbs. Relatedness in the Sorbs also influenced the power of uncorrected association analyses. CONCLUSIONS Sorbs show signs of genetic isolation which cannot be explained by over-sampling of relatives, but the effects are moderate in size. The Slavonic origin of the Sorbs is still genetically detectable. Regarding LD structure, a clear advantage for genome-wide association studies cannot be deduced. The significant amount of cryptic relatedness in the Sorbs sample results in inflated variances of Beta-estimators which should be considered in genetic association analyses. BACKGROUND The Sorbs are an ethnic minority in Germany with putative genetic isolation, making the population interesting for disease mapping. A sample of N = 977 Sorbs is currently analysed in several genome-wide meta-analyses. Since genetic differences between populations are a major confounding factor in genetic meta-analyses, we compare the Sorbs with the German outbred population of the KORA F3 study (N = 1644) and other publically available European HapMap populations by population genetic means. We also aim to separate effects of over-sampling of families in the Sorbs sample from effects of genetic isolation and compare the power of genetic association studies between the samples. RESULTS The degree of relatedness was significantly higher in the Sorbs. Principal components analysis revealed a west to east clustering of KORA individuals born in Germany, KORA individuals born in Poland or Czech Republic, Half-Sorbs (less than four Sorbian grandparents) and Full-Sorbs. The Sorbs cluster is nearest to the cluster of KORA individuals born in Poland. The number of rare SNPs is significantly higher in the Sorbs sample. FST between KORA and Sorbs is an order of magnitude higher than between different regions in Germany. Compared to the other populations, Sorbs show a higher proportion of individuals with runs of homozygosity between 2.5 Mb and 5 Mb. Linkage disequilibrium (LD) at longer range is also slightly increased but this has no effect on the power of association studies. Oversampling of families in the Sorbs sample causes detectable bias regarding higher FST values and higher LD but the effect is an order of magnitude smaller than the observed differences between KORA and Sorbs. Relatedness in the Sorbs also influenced the power of uncorrected association analyses. CONCLUSIONS Sorbs show signs of genetic isolation which cannot be explained by over-sampling of relatives, but the effects are moderate in size. The Slavonic origin of the Sorbs is still genetically detectable. Regarding LD structure, a clear advantage for genome-wide association studies cannot be deduced. The significant amount of cryptic relatedness in the Sorbs sample results in inflated variances of Beta-estimators which should be considered in genetic association analyses.

Authors: Arnd Gross, Anke Tönjes, Peter Kovacs, Krishna R. Veeramah, Peter Ahnert, Nab R. Roshyara, Christian Gieger, Ina-Maria Rueckert, Markus Loeffler, Mark Stoneking, Heinz-Erich Wichmann, John Novembre, Michael Stumvoll, Markus Scholz

Date Published: 2011

Publication Type: Journal article

Harmonization of growth hormone measurements with different immunoassays by data adjustment
Genetical Statistics and Systems Biology

Abstract (Expand)

BACKGROUND\backslashr\backslashnThe aim of our study was to evaluate the between-assay variability of commercially available immunoassays for the measurement of human growth hormone (hGH). In addition, … we asked whether the comparability of the diagnosis of childhood onset growth hormone deficiency could be improved by adjusting hGH results by statistical methods, such as linear regression, conversion factors, and quantile transformation.\backslashr\backslashnMETHODS\backslashr\backslashnIn archived sera from 312 children and adolescents (age: 17 days-17 years) hGH values between 0.01 and 16.5 ng/mL were determined by using the following immunoassays: AutoDELFIA (PerkinElmer), BC-IRMA (Beckman-Coulter), ELISA (Mediagnost), IMMULITE 2000 (Siemens), iSYS (IDS), Liaison (DiaSorin), UniCel DxI 800 Access (BeckmanCoulter) and {\textquotedblIn house{\textquotedbl-RIA (Tübingen).\backslashr\backslashnRESULTS\backslashr\backslashnThe assays differed in median hGH concentrations by as much as 5.44 ng/mL (Immulite), and as little as 2.67 ng/mL (BC-IRMA). The mean difference between assays ranged from 0.35 to 2.71 ng/mL, whereas several samples displayed differences up to 11.4 ng/mL. The best correlation (r=0.992) was found between AutoDELFIA and Liasion, the lowest (r=0.864) was between an in-house RIA and iSYS. The between-assay CV (mean \pm SD) of values within the cut-off range was 24.3% \pm 7.4%, resulting in an assay-dependent diagnosis of growth hormone deficiency (GHD) in more than 27% of patients. Yet, adjustment of this data by linear regression or a conversion factor reduced the CV below 14%, and the ratio of assay-dependent diagnoses below 8%. Using quantile transformation, the CV and ratio were reduced to 11.4% and \textless1%, respectively.\backslashr\backslashnCONCLUSIONS\backslashr\backslashnhGH measurements using different assays vary significantly. Linear regression, conversion factors, or particularly quantile transformation are useful tools to improve comparability in the diagnostic procedure for the confirmation of GHD in childhood and adolescence.

Authors: Anne Müller, Markus Scholz, Oliver Blankenstein, Gerhard Binder, Roland Pfäffle, Antje Körner, Wieland Kiess, Annegret Heider, Martin Bidlingmaier, Joachim Thiery, Jürgen Kratzsch

Date Published: 2011

Publication Type: Journal article

Spectral iEEG markers precede SSEP events during surgery for subarachnoid hemorrhage
Genetical Statistics and Systems Biology

Abstract (Expand)

OBJECTIVE\backslashr\backslashnDuring neurosurgical intracranial vascular manipulations, surgeons need early feed-back on the effects of temporary vascular occlusion. In surgical practice, commonly the … amplitude of somatosensory evoked potentials (SSEP) is monitored. However, the latency between an ischemic event and the drop of SSEP amplitude may amount to several minutes. Therefore intracranial electroencephalogram (iEEG) is tested for its predictive value.\backslashr\backslashnMETHODS\backslashr\backslashnDuring surgery in 13 patients, SSEP was recorded simultaneously with iEEG. iEEG was analyzed real-time in the frequency domain. Spectral observables of the iEEG were validated on the basis of SSEP by computing the statistical correlation first for the whole data set, then for salient events occurring in the SSEP in the group of patients, and finally for salient events occurring in single patients.\backslashr\backslashnRESULTS\backslashr\backslashnPlacement of subdural strip electrodes was compatible with standard surgical routine. Maximal correlation between time series of iEEG and SSEP was found for relative alpha power, which preceded the drop of SSEP by 7min.\backslashr\backslashnCONCLUSIONS\backslashr\backslashniEEG is feasible during neurosurgical intracranial vascular manipulations. Monitoring relative alpha power detects salient events earlier than SSEP.\backslashr\backslashnSIGNIFICANCE\backslashr\backslashnEarly detection of salient events facilitates early reaction of the surgeon and may thereby aid to further reduce intraoperative morbidity.

Authors: Christian Wess, Johannes Sarnthein, Niklaus Krayenbühl, Markus Scholz, Ekkehard Kunze, Jürgen Meixensberger

Date Published: 1st Dec 2010

Publication Type: Journal article

Genetic regulation of serum phytosterol levels and risk of coronary artery disease
Genetical Statistics and Systems Biology

Abstract (Expand)

BACKGROUND\backslashr\backslashnPhytosterols are plant-derived sterols that are taken up from food and can serve as biomarkers of cholesterol uptake. Serum levels are under tight genetic control. We … used a genomic approach to study the molecular regulation of serum phytosterol levels and potential links to coronary artery disease (CAD).\backslashr\backslashnMETHODS AND RESULTS\backslashr\backslashnA genome-wide association study for serum phytosterols (campesterol, sitosterol, brassicasterol) was conducted in a population-based sample from KORA (Cooperative Research in the Region of Augsburg) (n=1495) with subsequent replication in 2 additional samples (n=1157 and n=1760). Replicated single-nucleotide polymorphisms (SNPs) were tested for association with premature CAD in a metaanalysis of 11 different samples comprising 13 764 CAD cases and 13 630 healthy controls. Genetic variants in the ATP-binding hemitransporter ABCG8 and at the blood group ABO locus were significantly associated with serum phytosterols. Effects in ABCG8 were independently related to SNPs rs4245791 and rs41360247 (combined P=1.6 x 10(-50) and 6.2 x 10(-25), respectively; n=4412). Serum campesterol was elevated 12% for each rs4245791 T-allele. The same allele was associated with 40% decreased hepatic ABCG8 mRNA expression (P=0.009). Effects at the ABO locus were related to SNP rs657152 (combined P=9.4x10(-13)). Alleles of ABCG8 and ABO associated with elevated phytosterol levels displayed significant associations with increased CAD risk (rs4245791 odds ratio, 1.10; 95% CI, 1.06 to 1.14; P=2.2 x 10(-6); rs657152 odds ratio, 1.13; 95% CI, 1.07 to 1.19; P=9.4 x 10(-6)), whereas alleles at ABCG8 associated with reduced phytosterol levels were associated with reduced CAD risk (rs41360247 odds ratio, 0.84; 95% CI, 0.78 to 0.91; P=1.3 x 10(-5)).\backslashr\backslashnCONCLUSION\backslashr\backslashnCommon variants in ABCG8 and ABO are strongly associated with serum phytosterol levels and show concordant and previously unknown associations with CAD.

Authors: Daniel Teupser, Ronny Baber, Uta Ceglarek, Markus Scholz, Thomas Illig, Christian Gieger, Lesca Miriam Holdt, Alexander Leichtle, Karin H. Greiser, Dominik Huster, Patrick Linsel-Nitschke, Arne Schäfer, Peter S. Braund, Laurence Tiret, Klaus Stark, Dorette Raaz-Schrauder, Georg M. Fiedler, Wolfgang Wilfert, Frank Beutner, Stephan Gielen, Anika Grosshennig, Inke R. König, Peter Lichtner, Iris M. Heid, Alexander Kluttig, Nour E El Mokhtari, Diana Rubin, Arif B. Ekici, André Reis, Christoph D. Garlichs, Alistair S. Hall, Gert Matthes, Christian Wittekind, Christian Hengstenberg, Francois Cambien, Stefan Schreiber, Karl Werdan, Thomas Meitinger, Markus Loeffler, Nilesh J. Samani, Jeanette Erdmann, Heinz-Erich Wichmann, Heribert Schunkert, Joachim Thiery

Date Published: 1st Aug 2010

Publication Type: Journal article

Transapical aortic valve implantation in 100 consecutive patients: comparison to propensity-matched conventional aortic valve replacement
Genetical Statistics and Systems Biology

Abstract (Expand)

AIMS\backslashr\backslashnTo evaluate the outcome of transapical aortic valve implantation (TA-AVI) in comparison to conventional surgery.\backslashr\backslashnMETHODS AND RESULTS\backslashr\backslashnOne … hundred consecutive high-risk patients with symptomatic aortic valve stenosis received TA-AVI using the Edwards SAPIEN pericardial xenograft between February 2006 and January 2008. Patient age was 82.7 +/- 5 years, 77 were females, logistic EuroSCORE predicted risk of mortality was 29.4 +/- 13% and Society Thoracic Surgeons score risk for mortality was 15.2 +/- 8.3%. Propensity score analysis was used to identify a control group of patients that underwent conventional aortic valve replacement (C-AVR). Transapical aortic valve implantation was performed successfully in 97 patients, whereas three patients required early conversion. There were no new onset neurological events in the TA-AVI group and early extubation was performed in 82 patients. Echocardiography revealed good valve function with low transvalvular gradients in all patients. Thirty-day survival was 90 +/- 3 vs. 85 +/- 4% for TA-AVI vs. C-AVR, and 1-year survival was 73 +/- 4 vs. 69 +/- 5% (P = 0.55).\backslashr\backslashnCONCLUSION\backslashr\backslashnTransapical aortic valve implantation is a safe, minimally invasive, and off-pump technique to treat high-risk patients with aortic stenosis. Results of the initial 100 patients are good and compare favourably to conventional surgery.

Authors: Thomas Walther, Gerhard Schuler, Michael Andrew Borger, Joerg Kempfert, Jörg Seeburger, Yvonne Rückert, Joerg Ender, Axel Linke, Markus Scholz, Volkmar Falk, Friedrich Wilhelm Mohr

Date Published: 1st Jun 2010

Publication Type: Journal article

A biomathematical model of human thrombopoiesis under chemotherapy.
HaematoOpt - Individualized model-based managing of the next-cycle thrombopenia of CHOEP/CHOP treated patients based on platelets dynamics during the previous cycles

Abstract (Expand)

Intensification of cytotoxic chemotherapy enhances the outcome of several malignancies but is limited by haematotoxicity. While neutropenia and anaemia can be treated with supportive growth factor … applications, thrombocytopenia remains a dose-limiting side effect due to the lack of clinically approved pharmaceutical growth factors. Hence, it is necessary to assess the degree of thrombocytopenia of newly designed intensified regimens in the planning phase of a clinical trial. We present a simple ordinary differential equations model of thrombopoiesis under chemotherapy which maps the dynamics of stem cells, CFU-Mk, megakaryocytes and platelets in spleen and circulation. Major regulatory cytokine of thrombopoiesis is thrombopoietin (TPO) whose production and consumption is explicitly modelled. TPO acts by increasing the number of mitoses of CFU-Mk and increasing the mass and maturation of megakaryocytes. Chemotherapy is modelled by a drug-dose and cell-stage specific acute cell loss. Most of the cell kinetic parameters of the model were taken from literature. Parameters regarding TPO regulation and chemotherapy toxicity were estimated by fitting the predictions of the model to time series data of platelets received from large clinical data sets of patients under seven different chemotherapies. We obtained a good agreement between model and data for all scenarios. Parameter estimates were biologically plausible throughout. For validation, the model also explains data of TPO and platelet dynamics after thrombopheresis taken from literature. We used the model to make clinically relevant predictions. Regarding thrombocytopenia we estimated that the CHOP regimen for the treatment of high-grade non-Hodgkin's lymphoma can be time-intensified to a cycle duration of 12 days while the time-intensified CHOEP regimen would result in severe cumulative toxicity. We conclude that our proposed model proved validity for both, different chemotherapeutic regimens and thrombopheresis as well. It is useful to assess the thrombocytopenic risk in the planning phase of a clinical trial.

Authors: M. Scholz, A. Gross, M. Loeffler

Date Published: 21st May 2010

Publication Type: Not specified

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