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190 Publications visible to you, out of a total of 190
ASSOCIATION OF HIPPOCAMPAL VOLUMES WITH COGNITIVE TASKS IN A LARGE POPULATION-BASED COHORT
LIFE - Leipzig Research Center for Civilization Diseases

Abstract (Expand)

Background: Hippocampal volume, assessed via high-resolution MRI, is associated with memory and visuospatial performance in humans (Squire, 2004) and specifically prone to develop atrophy with age … (Apostolova,2015). This process has been linked to neurodegenerative diseases, such as Alzheimer’s disease (Apostolova,2015) and a decline of cognitive functions (Bruno,2016). However, due to differences in study-design and characteristics certain heterogeneity in results remains, in particular considering subfieldspecific effects (deFlores,2015). Therefore, we aim to determine the association of volumes of the whole hippocampus and its subfields on cognition in a large population-based cohort. Methods: Subjects: 1956 healthy participants from the Leipzig Research-Center-for-Civilization-Disease, aged 19-82years with MRI and neuropsychological tests (mean-age=57.61,±15.08SD). Exclusion: stroke, major-brain-pathologies, central-nervous-medication. Independent Variables: Volume of hippocampus and its subfields (CornuAmmonis1, 2-3, 4-DentateGyrus,(Pre-)subiculum). Dependent Variables: Verbal word-list learning, verbal-fluency, TrailMakingTask-(TMT)-A&B. Covariates: sex, age, years-of-education, total grey-mattervolume Image Analysis on high-resolution T1-images assessed at 3T. Hippocampal volumes were estimated using automatic segmentation analysis implemented in FreeSurfer (www.freesurfer.net). Statistical Analysis: Independent and dependent variables were first entered into Pearson Correlations. Variables with a correlation coefficient of r>0.1 were entered into multiple linear-regressions and adjusted for potential confounding(forward inclusion-model). Results: According to bivariate correlations, better performance in verbal-learning, verbal-fluency and TMT-A&B correlated moderately with larger whole-hippocampal volume and the volumes of all subfields(all |r|>0.102, all p0.046, all p0.5). Conclusions: Using a large cross-sectional cohort of healthy adults we found that volumes of the whole-hippocampus and subfields covering the CA4/dentate-gyrus region were weakly, yet specifically associated with verbal-learning and spatial processing-speed. Our preliminary results are in line with previous studies presuming a differential involvement of the hippocampus in tasks of verbal-learning and spatial processing (Oosterman,2010). Upcoming analyses implementing parcellation along the anteriorposterior- axis and random-effect-models might help to further disentangle these effects.

Authors: S. Huhn, R. Zhang, Frauke Beyer, L. Lampe, T. Luck, S. G. Riedel-Heller, M. L. Schroeter, Markus Löffler, M. Stumvoll, A. Villringer, A. V. Witte

Date Published: 1st Jul 2017

Publication Type: Not specified

Human Diseases: cognitive disorder, dementia

Model-based individual managing of thrombocytopenia during multi-cyclic 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)

Background: Thrombocytopenia is a major side-effect of cytotoxic cancer therapies. The aim of precision medicine is to develop therapy modifications accounting for the individual’s risk. Methodology/Principle … Findings: To solve this task, we develop an individualized bio-mechanistic model of the dynamics of bone marrow thrombopoiesis, circulating platelets and therapy effects thereon. Comprehensive biological knowledge regarding cell differentiation, amplification, apoptosis rates, transition times and corresponding regulations are translated into ordinary differential equations. A model of osteoblast/osteoclast interactions was incorporated to mechanistically describe bone marrow support of quiescent cell stages. Thrombopoietin (TPO) as a major regulator is explicitly modelled including pharmacokinetics and –dynamics of TPO injections. Effects of cytotoxic drugs are modelled by transient depletions of proliferating cells. To calibrate the model, we used population data from the literature and close-meshed individual data of N=135 high-grade non-Hodgkin’s lymphoma patients treated with CHOP-like chemotherapies. To limit the number of free parameters, several parsimony assumptions were derived from biological data and tested via Likelihood methods. Heterogeneity of patients was explained by a few model parameters. The over-fitting issue of individual parameter estimation was successfully dealt with a virtual participation of each patient in population-based experiments. The model qualitatively and quantitatively explains a number of biological observations such as the role of osteoblasts in explaining long-term toxic effects, megakaryocyte-mediated feedback on stem cells, bi-phasic stimulation of thrombopoiesis by TPO, dynamics of megakaryocyte ploidies and non-exponential platelet degradation. Almost all individual time series could be described with high precision. We demonstrated how the model can be used to provide predictions regarding individual therapy adaptations. Conclusions: We propose a mechanistic thrombopoiesis model of unprecedented comprehensiveness in both, biological mechanisms considered and experimental data sets explained. Our innovative method of parameter estimation allows robust determinations of individual parameter settings facilitating the development of individual treatment adaptations during chemotherapy.

Authors: Y. Kheifetz, Markus Scholz, Markus Löffler

Date Published: 9th Jun 2017

Publication Type: Not specified

Human Diseases: thrombocytopenia

Validity and intraobserver reliability of three-dimensional scanning compared with conventional anthropometry for children and adolescents from a population-based cohort study
Genetical Statistics and Systems Biology

Abstract (Expand)

BACKGROUND Conventional anthropometric measurements are time consuming and require well trained medical staff. To use three-dimensional whole body laser scanning in daily clinical work, validity, and …d reliability have to be confirmed. METHODS We compared a whole body laser scanner with conventional anthropometry in a group of 473 children and adolescents from the Leipzig Research Centre for Civilization Diseases (LIFE-Child). Concordance correlation coefficients (CCC) were calculated separately for sex, weight, and age to assess validity. Overall CCC (OCCC) was used to analyze intraobserver reliability. RESULTS Body height and the circumferences of waist, hip, upper arm, and calf had an \textquotedblexcellent\textquotedbl (CCC ≥0.9); neck and thigh circumference, a \textquotedblgood\textquotedbl (CCC ≥0.7); and head circumference, a \textquotedbllow\textquotedbl (CCC \textless 0.5) degree of concordance over the complete study population. We observed dependencies of validity on sex, weight, and age. Intraobserver reliability of both techniques is \textquotedblexcellent\textquotedbl (OCCC ≥0.9). CONCLUSION Scanning is faster, requires less intensive staff training and provides more information. It can be used in an epidemiologic setting with children and adolescents but some measurements should be considered with caution due to reduced agreement with conventional anthropometry.

Authors: Fabian Glock, Mandy Vogel, Stephanie Naumann, Andreas Kuehnapfel, Markus Scholz, Andreas Hiemisch, Toralf Kirsten, Kristin Rieger, Antje Koerner, Markus Loeffler, Wieland Kiess

Date Published: 1st May 2017

Publication Type: Journal article

Higher body mass index is associated with reduced posterior default mode connectivity in older adults.
LIFE Adult

Abstract (Expand)

Obesity is a complex neurobehavioral disorder that has been linked to changes in brain structure and function. However, the impact of obesity on functional connectivity and cognition in aging humans … is largely unknown. Therefore, the association of body mass index (BMI), resting-state network connectivity, and cognitive performance in 712 healthy, well-characterized older adults of the Leipzig Research Center for Civilization Diseases (LIFE) cohort (60-80 years old, mean BMI 27.6 kg/m(2) +/- 4.2 SD, main sample: n = 521, replication sample: n = 191) was determined. Statistical analyses included a multivariate model selection approach followed by univariate analyses to adjust for possible confounders. Results showed that a higher BMI was significantly associated with lower default mode functional connectivity in the posterior cingulate cortex and precuneus. The effect remained stable after controlling for age, sex, head motion, registration quality, cardiovascular, and genetic factors as well as in replication analyses. Lower functional connectivity in BMI-associated areas correlated with worse executive function. In addition, higher BMI correlated with stronger head motion. Using 3T neuroimaging in a large cohort of healthy older adults, independent negative associations of obesity and functional connectivity in the posterior default mode network were observed. In addition, a subtle link between lower resting-state connectivity in BMI-associated regions and cognitive function was found. The findings might indicate that obesity is associated with patterns of decreased default mode connectivity similar to those seen in populations at risk for Alzheimer's disease. Hum Brain Mapp 38:3502-3515, 2017. (c) 2017 Wiley Periodicals, Inc.

Authors: F. Beyer, S. Kharabian Masouleh, J. M. Huntenburg, L. Lampe, T. Luck, S. G. Riedel-Heller, M. Loeffler, M. L. Schroeter, M. Stumvoll, A. Villringer, A. V. Witte

Date Published: 12th Apr 2017

Publication Type: Journal article

Human Diseases: obesity

Limited role for extended maintenance temozolomide for newly diagnosed glioblastoma.
GGN - German Glioma Network

Abstract (Expand)

OBJECTIVE: To explore an association with survival of modifying the current standard of care for patients with newly diagnosed glioblastoma of surgery followed by radiotherapy plus concurrent and 6 … cycles of maintenance temozolomide chemotherapy (TMZ/RT --> TMZ) by extending TMZ beyond 6 cycles. METHODS: The German Glioma Network cohort was screened for patients with newly diagnosed glioblastoma who received TMZ/RT --> TMZ and completed >/=6 cycles of maintenance chemotherapy without progression. Associations of clinical patient characteristics, molecular markers, and residual tumor determined by magnetic resonance imaging after 6 cycles of TMZ with progression-free survival (PFS) and overall survival (OS) were analyzed with the log-rank test. Multivariate analyses using the Cox proportional hazards model were performed to assess associations of prolonged TMZ use with outcome. RESULTS: Sixty-one of 142 identified patients received at least 7 maintenance TMZ cycles (median 11, range 7-20). Patients with extended maintenance TMZ treatment had better PFS (20.5 months, 95% confidence interval [CI] 17.7-23.3, vs 17.2 months, 95% CI 10.2-24.2, p = 0.035) but not OS (32.6 months, 95% CI 28.9-36.4, vs 33.2 months, 95% CI 25.3-41.0, p = 0.126). However, there was no significant association of prolonged TMZ chemotherapy with PFS (hazard ratio [HR] = 0.8, 95% CI 0.4-1.6, p = 0.559) or OS (HR = 1.6, 95% CI 0.8-3.3, p = 0.218) adjusted for age, extent of resection, Karnofsky performance score, presence of residual tumor, O(6)-methylguanine DNA methyltransferase (MGMT) promoter methylation status, or isocitrate dehydrogenase (IDH) mutation status. CONCLUSION: These data may not support the practice of prolonging maintenance TMZ chemotherapy beyond 6 cycles. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that in patients with newly diagnosed glioblastoma, prolonged TMZ chemotherapy does not significantly increase PFS or OS.

Authors: D. Gramatzki, P. Kickingereder, B. Hentschel, J. Felsberg, U. Herrlinger, G. Schackert, J. C. Tonn, M. Westphal, M. Sabel, U. Schlegel, W. Wick, T. Pietsch, G. Reifenberger, M. Loeffler, M. Bendszus, M. Weller

Date Published: 11th Apr 2017

Publication Type: Journal article

Human Diseases: brain glioblastoma multiforme

Genome-wide meta-analysis identifies novel loci of plaque burden in carotid artery.
Genetical Statistics and Systems Biology

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

Predicting brain-age from multimodal imaging data captures cognitive impairment.
LIFE Adult

Abstract (Expand)

The disparity between the chronological age of an individual and their brain-age measured based on biological information has the potential to offer clinically relevant biomarkers of neurological … syndromes that emerge late in the lifespan. While prior brain-age prediction studies have relied exclusively on either structural or functional brain data, here we investigate how multimodal brain-imaging data improves age prediction. Using cortical anatomy and whole-brain functional connectivity on a large adult lifespan sample (N=2354, age 19-82), we found that multimodal data improves brain-based age prediction, resulting in a mean absolute prediction error of 4.29 years. Furthermore, we found that the discrepancy between predicted age and chronological age captures cognitive impairment. Importantly, the brain-age measure was robust to confounding effects: head motion did not drive brain-based age prediction and our models generalized reasonably to an independent dataset acquired at a different site (N=475). Generalization performance was increased by training models on a larger and more heterogeneous dataset. The robustness of multimodal brain-age prediction to confounds, generalizability across sites, and sensitivity to clinically-relevant impairments, suggests promising future application to the early prediction of neurocognitive disorders.

Authors: F. Liem, G. Varoquaux, J. Kynast, F. Beyer, S. Kharabian Masouleh, J. M. Huntenburg, L. Lampe, M. Rahim, A. Abraham, R. C. Craddock, S. Riedel-Heller, T. Luck, M. Loeffler, M. L. Schroeter, A. V. Witte, A. Villringer, D. S. Margulies

Date Published: 1st Mar 2017

Publication Type: Journal article

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