5 results on '"Fischer, Lukas"'
Search Results
2. Right heart size and function significantly correlate in patients with pulmonary arterial hypertension – a cross-sectional study
- Author
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Fischer, Lukas, Benjamin, Nicola, Blank, Norbert, Egenlauf, Benjamin, Fischer, Christine, Harutyunova, Satenik, Koegler, Maria, Lorenz, Hanns-Martin, Marra, Alberto M., Nagel, Christian, Xanthouli, Panagiota, Bossone, Eduardo, and Grünig, Ekkehard
- Published
- 2018
- Full Text
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3. Analysis of the three-dimensional anatomical variance of the distal radius using 3D shape models
- Author
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Baumbach, Sebastian F., Binder, Jakob, Synek, Alexander, Mück, Fabian G., Chevalier, Yan, Euler, Ekkehard, Langs, Georg, and Fischer, Lukas
- Subjects
Adult ,Male ,Models, Anatomic ,Middle Aged ,Radius ,Imaging, Three-Dimensional ,Image processing ,Radiology Nuclear Medicine and imaging ,Distal radius ,Image Processing, Computer-Assisted ,Humans ,Female ,Statistical model ,Anatomical model ,Tomography, X-Ray Computed ,Computed tomography ,Research Article ,Retrospective Studies - Abstract
Background Various medical fields rely on detailed anatomical knowledge of the distal radius. Current studies are limited to two-dimensional analysis and biased by varying measurement locations. The aims were to 1) generate 3D shape models of the distal radius and investigate variations in the 3D shape, 2) generate and assess morphometrics in standardized cut planes, and 3) test the model’s classification accuracy. Methods The local radiographic database was screened for CT-scans of intact radii. 1) The data sets were segmented and 3D surface models generated. Statistical 3D shape models were computed (overall, gender and side separate) and the 3D shape variation assessed by evaluating the number of modes. 2) Anatomical landmarks were assigned and used to define three standardized cross-sectional cut planes perpendicular to the main axis. Cut planes were generated for the mean shape models and each individual radius. For each cut plane, the following morphometric parameters were calculated and compared: maximum width and depth, perimeter and area. 3) The overall shape model was utilized to evaluate the predictive value (leave one out cross validation) for gender and side identification within the study population. Results Eighty-six radii (45 left, 44% female, 40 ± 18 years) were included. 1) Overall, side and gender specific statistical 3D models were successfully generated. The first mode explained 37% of the overall variance. Left radii had a higher shape variance (number of modes: 20 female / 23 male) compared to right radii (number of modes: 6 female / 6 male). 2) Standardized cut planes could be defined using anatomical landmarks. All morphometric parameters decreased from distal to proximal. Male radii were larger than female radii with no significant side difference. 3) The overall shape model had a combined median classification probability for side and gender of 80%. Conclusions Statistical 3D shape models of the distal radius can be generated using clinical CT-data sets. These models can be used to assess overall bone variance, define and analyze standardized cut-planes, and identify the gender of an unknown sample. These data highlight the potential of shape models to assess the 3D anatomy and anatomical variance of human bones. Electronic supplementary material The online version of this article (doi:10.1186/s12880-017-0193-9) contains supplementary material, which is available to authorized users.
- Published
- 2017
4. Cloning of transgenic tobacco BY-2 cells; an efficient method to analyse and reduce high natural heterogeneity of transgene expression.
- Author
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Nocarova, Eva and Fischer, Lukas
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CLONING , *TOBACCO , *PLANT genetics , *PLANT genetic engineering , *GREEN fluorescent protein , *TRANSGENES - Abstract
Background: Phenotypic characterization of transgenic cell lines, frequently used in plant biology studies, is complicated because transgene expression in individual cells is often heterogeneous and unstable. To identify the sources and to reduce this heterogeneity, we transformed tobacco (Nicotiana tabacum L.) BY-2 cells with a gene encoding green fluorescent protein (GFP) using Agrobacterium tumefaciens, and then introduced a simple cloning procedure to generate cell lines derived from the individual transformed cells. Expression of the transgene was monitored by analysing GFP fluorescence in the cloned lines and also in lines obtained directly after transformation. Results: The majority (~90%) of suspension culture lines derived from calli that were obtained directly from transformation consisted of cells with various levels of GFP fluorescence. In contrast, nearly 50% of lines generated by cloning cells from the primary heterogeneous suspensions consisted of cells with homogenous GFP fluorescence. The rest of the lines exhibited "permanent heterogeneity" that could not be resolved by cloning. The extent of fluorescence heterogeneity often varied, even among genetically identical clones derived from the primary transformed lines. In contrast, the offspring of subsequent cloning of the cloned lines was uniform, showing GFP fluorescence intensity and heterogeneity that corresponded to the original clone. Conclusion: The results demonstrate that, besides genetic heterogeneity detected in some lines, the primary lines often contained a mixture of epigenetically different cells that could be separated by cloning. This indicates that a single integration event frequently results in various heritable expression patterns, which are probably accidental and become stabilized in the offspring of the primary transformed cells early after the integration event. Because heterogeneity in transgene expression has proven to be a serious problem, it is highly advisable to use transgenes tagged with a visual marker for BY-2 transformation. The cloning procedure can be used not only for efficient reduction of expression heterogeneity of such transgenes, but also as a useful tool for studies of transgene expression and other purposes. [ABSTRACT FROM AUTHOR]
- Published
- 2009
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5. Morphological and molecular characterization of a spontaneously tuberizing potato mutant: an insight into the regulatory mechanisms of tuber induction.
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Fischer L, Lipavska H, Hausman JF, and Opatrny Z
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- Biomass, Carbohydrate Metabolism drug effects, Carbohydrate Metabolism radiation effects, DNA, Bacterial metabolism, DNA, Ribosomal genetics, Gene Expression Regulation, Plant drug effects, Gene Expression Regulation, Plant radiation effects, Genes, Plant, Gibberellins pharmacology, Light, Mutagenesis, Insertional, Photoperiod, Plant Leaves drug effects, Plant Leaves metabolism, Plant Leaves radiation effects, Plant Stems drug effects, Plant Stems metabolism, Plant Stems radiation effects, Plant Tubers drug effects, Plant Tubers radiation effects, Proteome metabolism, RNA, Untranslated genetics, Soil, Solanum tuberosum drug effects, Solanum tuberosum radiation effects, Starch metabolism, Sucrose pharmacology, Mutation genetics, Plant Tubers genetics, Plant Tubers metabolism, Solanum tuberosum genetics, Solanum tuberosum metabolism
- Abstract
Background: Tuberization in potato (Solanum tuberosum L.) represents a morphogenetic transition of stolon growth to tuber formation, which is under complex environmental and endogenous regulation. In the present work, we studied the regulatory mechanisms and the role of different morphogenetic factors in a newly isolated potato mutant, which exhibited spontaneous tuberization (ST). The ST mutant was characterized in detail at morphological, physiological and biochemical levels., Results: Tuberization of the ST mutant grown in the soil was photoperiod-insensitive; predominantly sessile tubers formed directly from axillary buds even under continuous light. Single-node cuttings of the ST mutant cultured in vitro frequently formed tubers or basal tuber-like swellings instead of normal shoots under conditions routinely used for shoot propagation. The tuberization response of ST cuttings under light was dependent on sucrose, the concentration of which had to exceed certain threshold that inversely correlated with irradiance. Gibberellic acid prevented tuberization of ST cuttings, but failed to restore normal shoot phenotype and caused severe malformations. Carbohydrate analysis showed increased levels of both soluble sugars and starch in ST plants, with altered carbohydrate partitioning and metabolism. Comparative proteomic analysis revealed only a few differences between ST- and wild-type plants, primary amongst which seemed to be the absence of an isoform of manganese-stabilizing protein, a key subunit of photosystem II., Conclusion: ST mutant exhibits complex developmental and phenotypic modifications, with features that are typical for plants strongly induced to tuberize. These changes are likely to be related to altered regulation of photosynthesis and carbohydrate metabolism rather than impaired transduction of inhibitory gibberellin or photoperiod-based signals. The effect of gibberellins on tuberization of ST mutant suggests that gibberellins inhibit tuberization downstream of the inductive effects of sucrose and other positive factors.
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- 2008
- Full Text
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