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958 Publications visible to you, out of a total of 958
Impact of image acquisition on voxel-based-morphometry investigations of age-related structural brain changes.
LIFE Adult

Abstract (Expand)

A growing number of magnetic resonance imaging studies employ voxel-based morphometry (VBM) to assess structural brain changes. Recent reports have shown that image acquisition parameters may influence … VBM results. For systematic evaluation, gray-matter-density (GMD) changes associated with aging were investigated by VBM employing acquisitions with different radiofrequency head coils (12-channel matrix coil vs. 32-channel array), different pulse sequences (MP-RAGE vs. MP2RAGE), and different voxel dimensions (1mm vs. 0.8mm). Thirty-six healthy subjects, classified as young, middle-aged, or elderly, participated in the study. Two-sample and paired t-tests revealed significant effects of acquisition parameters (coil, pulse sequence, and resolution) on the estimated age-related GMD changes in cortical and subcortical regions. Potential advantages in tissue classification and segmentation were obtained for MP2RAGE. The 32-channel coil generally outperformed the 12-channel coil, with more benefit for MP2RAGE. Further improvement can be expected from higher resolution if the loss in SNR is accounted for. Use of inconsistent acquisition parameters in VBM analyses is likely to introduce systematic bias. Overall, acquisition and protocol changes require careful adaptations of the VBM analysis strategy before generalized conclusion can be drawn.

Authors: D. P. Streitburger, A. Pampel, G. Krueger, J. Lepsien, M. L. Schroeter, K. Mueller, H. E. Moller

Date Published: 15th Feb 2014

Publication Type: Not specified

Impact of molecular screening for point mutations and rearrangements in routine air-dried fine-needle aspiration samples of thyroid nodules
Genetical Statistics and Systems Biology

Abstract (Expand)

BACKGROUND\backslashr\backslashnThe diagnostic limitations of thyroid fine-needle aspiration (FNA), such as the indeterminate category, can be partially overcome by molecular analyses. However, until … now, rearrangements have only been detected in fresh FNA material and the number of follicular thyroid carcinomas (FTCs) was rather low in previous studies. We aimed at investigating the impact of point mutations and rearrangement detection in a set of routine air-dried FNA smears with a higher percentage of FTCs.\backslashr\backslashnMETHODS\backslashr\backslashnRNA and DNA was extracted from 310 FNAs (164 indeterminate, 57 malignant, 89 benign) and corresponding formalin-fixed paraffin-embedded tissue (156 follicular adenomas [FAs], 32 FTCs, 44 papillary thyroid carcinomas [PTCs], 9 follicular variant PTCs, and 69 goiters). PAX8/PPARG and RET/PTC rearrangements were detected by qPCR, BRAF and RAS mutations by high-resolution melting PCR and by pyrosequencing.\backslashr\backslashnRESULTS\backslashr\backslashnForty-seven mutations were detected in the FNAs: 22 BRAF, 13 NRAS, and 3 HRAS mutations, 8 PAX8/PPARG, and one RET/PTC-rearrangement. While the presence of a BRAF and RET/PTC mutation was associated with cancer in 100% of samples each, the presence of a RAS and PAX8/PPARG mutation was associated with cancer in only 12% and 50% of samples, respectively. In the indeterminate group 4 of 25 carcinomas were identified by molecular FNA screening, which increased the sensitivity from 67% (cytology alone) to 75% (cytology plus molecular screening).\backslashr\backslashnCONCLUSION\backslashr\backslashnMolecular screening for point mutations and rearrangements is feasible in air-dried FNAs. Although the impact of detecting point mutations and rearrangements in FNAs has most likely been overestimated in previous studies, molecular FNA analyses improve presurgical diagnostics. The detection of BRAF mutations in FNA may improve the choice of surgery and postsurgical treatment. Further data are necessary to elucidate the true impact of detecting RAS and PAX8/PPARG mutations in FNAs. The inclusion of additional rare somatic mutations and miRNA markers might further improve the impact of molecular FNA diagnostics. BACKGROUND The diagnostic limitations of thyroid fine-needle aspiration (FNA), such as the indeterminate category, can be partially overcome by molecular analyses. However, until now, rearrangements have only been detected in fresh FNA material and the number of follicular thyroid carcinomas (FTCs) was rather low in previous studies. We aimed at investigating the impact of point mutations and rearrangement detection in a set of routine air-dried FNA smears with a higher percentage of FTCs. METHODS RNA and DNA was extracted from 310 FNAs (164 indeterminate, 57 malignant, 89 benign) and corresponding formalin-fixed paraffin-embedded tissue (156 follicular adenomas [FAs], 32 FTCs, 44 papillary thyroid carcinomas [PTCs], 9 follicular variant PTCs, and 69 goiters). PAX8/PPARG and RET/PTC rearrangements were detected by qPCR, BRAF and RAS mutations by high-resolution melting PCR and by pyrosequencing. RESULTS Forty-seven mutations were detected in the FNAs: 22 BRAF, 13 NRAS, and 3 HRAS mutations, 8 PAX8/PPARG, and one RET/PTC-rearrangement. While the presence of a BRAF and RET/PTC mutation was associated with cancer in 100% of samples each, the presence of a RAS and PAX8/PPARG mutation was associated with cancer in only 12% and 50% of samples, respectively. In the indeterminate group 4 of 25 carcinomas were identified by molecular FNA screening, which increased the sensitivity from 67% (cytology alone) to 75% (cytology plus molecular screening). CONCLUSION Molecular screening for point mutations and rearrangements is feasible in air-dried FNAs. Although the impact of detecting point mutations and rearrangements in FNAs has most likely been overestimated in previous studies, molecular FNA analyses improve presurgical diagnostics. The detection of BRAF mutations in FNA may improve the choice of surgery and postsurgical treatment. Further data are necessary to elucidate the true impact of detecting RAS and PAX8/PPARG mutations in FNAs. The inclusion of additional rare somatic mutations and miRNA markers might further improve the impact of molecular FNA diagnostics.

Authors: Markus Eszlinger, Annelise Krogdahl, Sina Münz, Christian Rehfeld, Eva Magrethe Precht Jensen, Carolina Ferraz, Eileen Bösenberg, Norbert Drieschner, Markus Scholz, Laszlo Hegedüs, Ralf Paschke

Date Published: 1st Feb 2014

Publication Type: Journal article

Modelling lymphoma therapy and outcome
Genetical Statistics and Systems Biology

Abstract (Expand)

Dose and time intensifications of chemotherapy improved the outcome of lymphoma therapy. However, recent study results show that too intense therapies can result in inferior tumour control. We hypothesise … that the immune system plays a key role in controlling residual tumour cells after treatment. More intense therapies result in a stronger depletion of immune cells allowing an early re-growth of the tumour.We propose a differential equations model of the dynamics and interactions of tumour and immune cells under chemotherapy. Major model features are an exponential tumour growth, a modulation of the production of effector cells by the presence of the tumour (immunogenicity), and mutual destruction of tumour and immune cells. Chemotherapy causes damage to both, immune and tumour cells. Growth rate, chemosensitivity, immunogenicity, and initial size of the tumour are assumed to be patient-specific, resulting in heterogeneity regarding therapy outcome. Maximum-entropy distributions of these parameters were estimated on the basis of clinical survival data. The resulting model can explain the outcome of five different chemotherapeutic regimens and corresponding hazard-ratios.We conclude that our model explains observed paradox effects in lymphoma therapy by the simple assumption of a relevant anti-tumour effect of the immune system. Heterogeneity of therapy outcomes can be explained by distributions of model parameters, which can be estimated on the basis of clinical survival data. We demonstrate how the model can be used to make predictions regarding yet untested therapy options.

Authors: Katja Roesch, Dirk Hasenclever, Markus Scholz

Date Published: 1st Feb 2014

Publication Type: Journal article

Suboptimal dosing of rituximab in male and female patients with DLBCL.
GLA - German Lymphoma Alliance

Abstract (Expand)

To determine the effect of gender on outcome, the male hazard ratio for progression-free survival (HRPFS-male) was determined in patients with diffuse large B-cell lymphoma (DLBCL). In young patients … (MapThera International Trial study), HRPFS-male was 1.3 (P = .092) without and 1.1 (P = .660) with rituximab. In elderly patients (RICOVER-60 study), HRPFS-male was 1.1 (P = .348) with CHOP but increased to 1.6 (P = .004) with R-CHOP. The similar improvements of outcome in young patients were associated with similar rituximab clearances in young males and females (9.89 vs 10.38 mL/h; P = .238), whereas the greater benefit for elderly females was associated with a slower rituximab clearance (8.47 vs 10.59 mL/h; P = .005) and hence higher serum levels and longer exposure times, attributable to an age-dependent (P = .004) decrease of rituximab clearance in females but not males. Compared with elderly females, all other subgroups had significantly faster rituximab clearances and hence appear to be suboptimally dosed when rituximab is given at 375 mg/m(2). Although early results of pharmacokinetic-based prospective trials designed to exploit the full therapeutic potential of rituximab suggest that increased doses and/or prolonged exposure times can improve the outcome of elderly males with DLBCL, further studies are warranted that address the optimization of rituximab dose and schedule in all subgroups of DLBCL patients.

Authors: M. Pfreundschuh, C. Muller, S. Zeynalova, E. Kuhnt, M. H. Wiesen, G. Held, T. Rixecker, V. Poeschel, C. Zwick, M. Reiser, N. Schmitz, N. Murawski

Date Published: 30th Jan 2014

Publication Type: Not specified

Human Diseases: diffuse large B-cell lymphoma

Portraying the expression landscapes of cancer subtypes. A case study of glioblastoma multiforme and prostate cancer
HNPCC-Sys - Genomic and transcriptomic heterogeneity of colorectal tumours arising in Lynch syndrome, GGN - German Glioma Network

Abstract (Expand)

Self-organizing maps (SOM) portray molecular phenotypes with individual resolution. We present an analysis pipeline based on SOM machine learning which allows the comprehensive study of large scale … clinical data. The potency of the method is demonstrated in selected applications studying the diversity of gene expression in Glioblastoma Multiforme (GBM) and prostate cancer progression. Our method characterizes relationships between the samples, disentangles the expression patterns into well separated groups of co-regulated genes, extracts their functional contexts using enrichment techniques, and enables the detection of contaminations and outliers in the samples. We found that the four GBM subtypes can be divided into two “localized” and two “intermediate” ones. The localized subtypes are characterized by the antagonistic activation of processes related to immune response and cell division, commonly observed also in other cancers. In contrast, each of the “intermediate” subtypes forms a heterogeneous continuum of expression states linking the “localized” subtypes. Both “intermediate” subtypes are characterized by distinct expression patterns related to translational activity and innate immunity as well as nervous tissue and cell function. We show that SOM portraits provide a comprehensive framework for the description of the diversity of expression landscapes using concepts of molecular function.

Authors: Lydia Hopp, Henry Löffler-Wirth, M. Fasold, Hans Binder

Date Published: 27th Jan 2014

Publication Type: Not specified

Human Diseases: brain glioma, prostate cancer

Significant dose Escalation of Idarubicin in the treatment of aggressive Non- Hodgkin Lymphoma leads to increased hematotoxicity without improvement in efficacy in comparison to standard CHOEP-14: 9-year follow up results of the CIVEP trial of the DSHNHL.
GLA - German Lymphoma Alliance

Abstract (Expand)

BACKGROUND: Dose escalation and modification of CHOP has improved the prognosis of patients with aggressive lymphoma; even in the rituximab era, dose escalation for high-risk patients is exploited and … frequently limited by drug toxicity. Idarubicin (Id) is a 4-demethoxy anthracycline analogue of daunorubicin with activity against lymphoma and has been reported to cause less cardiotoxicity than other anthracylines. The aim of this study was to replace doxorubicine with idarubicin in the CHOEP regimen and to find the maximum tolerable dose (MTD) of idarubicin based on hematotoxicity. PATIENTS AND METHODS: Between 11/96 and 09/98, 64 patients (pts) aged 18-75 yrs (pts. 18-60, LDH not elevated, >60 years all risk groups) with newly diagnosed aggressive lymphoma received 6 cycles of CIVEP-14 with an escalating dose of idarubicin, consisting of idarubicin (11-16 mg/m(2) d1) and standard doses of cyclophosphamide, vincristine, etoposide, and prednisone with G-CSF support. RESULTS: 55 pts (median age 56 yrs) were evaluable for a final analysis with a median observation time of 9.3 years. The CR-rate was 77.4% ; the 5 and 8-year-EFS rates were 46.4% (95%CI 32.5-60.3%) and 43.5% (29.4-57.6%), respectively, and the 5- and 8 yr OS rates were 64.6% (51.7-77.5%) and 59.9% (46.4-73.4%). 14/55 patients have died due to lymphoma progression, and 2/55 patients (3.6%) due to treatment related toxicity, 4/55 due to other causes (3 infections, 1 acute heart failure). In a matched pair analysis comparing CHOEP-14 and CIVEP-14, CIVEP-14 had a higher hematotoxicity with no significant differences in the event free and overall survival for the two regimens. CONCLUSIONS: Thus, idarubicin cannot be used instead doxorubicin even if its dose is escalated to achieve similar hematotoxicity. Doxorubicin remains the standard anthracycline for the treatment of aggressive NHL.

Authors: K. Hohloch, C. Zwick, M. Ziepert, D. Hasenclever, U. Kaiser, A. Engert, H. G. Hoffkes, F. Kroschinsky, R. Mesters, A. C. Feller, M. Loffler, L. Trumper, M. Pfreundschuh

Date Published: 3rd Jan 2014

Publication Type: Not specified

Human Diseases: non-Hodgkin lymphoma

Methylation associated pathway activity deregulation in lung adenocarcinoma
CapSys - Systems Medicine of Community Acquired Pneumonia

Abstract (Expand)

Methylation impairments are tightly associated with gene expression and molecular pathway deregulation in cancer development. However, other regulatory mechanisms exist, making it important to distinguish … those from methylation driven changes. Here we specifically assessed molecular pathway states associated with gene methylation in lung adenocarcinoma. Paired gene expression and methylation data (id:GSE32867) were obtained from Gene Expression Omnibus. Self organizing maps (Wirth, H. et al.BMC Bioinformatics 2011;12:306 ) and in-house pathway signal flow algorithms were applied to describe expression (PSF) and methylation (mPSF) states in KEGG pathways. 35 and 24 KEGG pathways had at least one branch deregulated at significance levels p<0.05 and 0.05<p < 0.1, respectively. Because many pathways are multibranch, our analysis totalled in 54 up- (PSF>1) and 73 down-regulated (PSF<1) branches. From these branches, 19 were positively (mPSF<0) or negatively (mPSF>0) correlated with methylation states (see table).

Authors: L. Nersisyan, Henry Löffler-Wirth, A. Gevorgyan, Hans Binder, A. Arakelyan

Date Published: 2014

Publication Type: Not specified

Human Diseases: lung disease

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