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Search Results: 1 - 10 of 5497 matches for " Markus Lamla "
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Enhancing Endosomal Escape of Transduced Proteins by Photochemical Internalisation
Kevin Mellert, Markus Lamla, Klaus Scheffzek, Rainer Wittig, Dieter Kaufmann
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0052473
Abstract: Induced internalisation of functional proteins into cultured cells has become an important aspect in a rising number of in vitro and in vivo assays. The endo-lysosomal entrapment of the transduced proteins remains the major problem in all transduction protocols. In this study we compared the efficiency, cytotoxicity and protein targeting of different commercially available transduction reagents by transducing a well-studied fluorescently labelled protein (Atto488-bovine serum albumin) into cultured human sarcoma cells. The amount of internalised protein and toxicity differed between the different reagents, but the percentage of transduced cells was consistently high. Furthermore, in all protocols the signals of the transduced Atto488-BSA were predominantly punctual consistent with an endosomal localisation. To overcome the endosomal entrapment, the transduction protocols were combined with a photochemical internalisation (PCI) treatment. Using this combination revealed that an endosomal disruption is highly effective in cell penetrating peptide (CPP) mediated transduction, whereas lipid-mediated transductions lead to a lower signal spreading throughout the cytosol. No change in the signal distribution could be achieved in treatments using non-lipid polymers as a transduction reagent. Therefore, the combination of protein transduction protocols based on CPPs with the endosomolytic treatment PCI can facilitate protein transduction experiments in vitro.
Aberrant Single Exon Skipping is not Altered by Age in Exons of NF1, RABAC1, AATF or PCGF2 in Human Blood Cells and Fibroblasts
Kevin Mellert,Michael Uhl,Josef H?gel,Markus Lamla,Ralf Kemkemer,Dieter Kaufmann
Genes , 2011, DOI: 10.3390/genes2030562
Abstract: In human pre-mRNA splicing, infrequent errors occur resulting in erroneous splice products as shown in a genome-wide approach. One characteristic subgroup consists of products lacking one cassette exon. The noise in the splicing process, represented by those misspliced products, can be increased by cold shock treatment or by inhibiting the nonsense mediated decay. Here, we investigated whether the splicing noise frequency increases with age in vivo in peripheral bloods cells or in vitro in cultured and aged fibroblasts from healthy donors. Splicing noise frequency was measured for four erroneously skipped NF1 exons and one exon of RABAC1, AATF and PCGF2 by RT-qPCR. Measurements were validated in cultured fibroblasts treated with cold shock or puromycin. Intragenic but not interpersonal differences were detected in splicing noise frequencies in vivo in peripheral blood cells of 11 healthy donors (15 y–85 y) and in in vitro senescent fibroblasts from three further donors. No correlation to the age of the donors was found in the splicing noise frequencies. Our data demonstrates that splicing error frequencies are not altered by age in peripheral blood cells or in vitro aged fibroblasts in the tested exons of the four investigated genes, indicating a high importance of correct splicing in these proliferating aged cells.
Cyclic stretch increases splicing noise rate in cultured human fibroblasts
Michael Uhl, Kevin Mellert, Britta Striegl, Martin Deibler, Markus Lamla, Joachim P Spatz, Ralf Kemkemer, Dieter Kaufmann
BMC Research Notes , 2011, DOI: 10.1186/1756-0500-4-470
Abstract: The amount of splicing noise was measured by RT-qPCR of seven exon skips from the test genes AATF, MAP3K11, NF1, PCGF2, POLR2A and RABAC1. In cells treated by altered uniaxial cyclic stretching for 18 h, a uniform and significant increase of splicing noise was found for all detectable exon skips.Our data demonstrate that application of cyclic stretch to cultured fibroblasts correlates with a reduced transcriptional fidelity caused by increasing splicing noise.Eukaryotic cells sense the physical properties of their microenvironment by translating mechanical forces into biochemical signals. This mechanotransduction and its triggered biological responses are crucial for the regulation of many important cellular functions [1-4]. Mechanical forces are also transmitted to the nucleus through the cytoskeleton by extra- or intracellular force generation [5-7]. Even though the nucleus is suggested to be stiffer than the surrounding cytoskeleton [8,9], extracellular forces and strain result in clearly detectable deformations of the nucleus [5,10] that can in turn induce conformational changes in chromatin organization and transcriptional regulation [11-14].A common experimental approach permitting to investigate the effects of mechanical forces on cells in vitro is cyclic stretching of cultured cells plated on an expandable elastomeric substrate coated with extracellular matrix components such as fibronectin. The cells dynamically align their cell bodies and cytoskeletons in a direction perpendicular to the strain [15]. The mean cell orientation changes exponentially with a frequency-dependent characteristic time from 1 to 5 h [16]. Mechanisms involved in force-induced cellular reorganisation are focal-adhesion sliding, RhoA activation and the actomyosin machinery, whereas the process seems to be largely independent of the dynamic microtubule network [17,18]. Together with the cells, their nuclei also become deformed [16,19]. Numerous in vitro studies have shown that cyclic s
Atypical squamous cells, cannot exclude high grade squamous intraepithelial (ASC-H) in HIV-positive women
Michelow Pam,Hartman Ingrid,Schulze Doreen,Lamla-Hillie Stella
CytoJournal , 2010,
Abstract: Objective: South Africa has very high rates of both HIV infection and cervical pathology. The management of ASC-H is colposcopy and directed biopsy, but with so many women diagnosed with HSIL and a dearth of colposcopy centres in South Africa, women with cytologic diagnosis of ASC-H may not be prioritized for colposcopy. The aim of this study was to determine if HIV-positive women with a cytologic diagnosis of ASC-H should undergo immediate colposcopy or whether colposcopy can be delayed, within the context of an underfunded health care setting with so many competing health needs. Materials and Methods: A computer database search was performed from the archives of an NGO-administered clinic that offers comprehensive HIV care. All women with a cytologic diagnosis of ASC-H on cervical smears from September 2005 until August 2009 were identified. Histologic follow up was sought in all patients. Results: A total of 2111 cervical smears were performed and 41 diagnosed as ASC-H (1.94%). No histologic follow up data was available in 15 cases. Follow up histologic results were as follows: three negative (11.5%), five koilocytosis and/ or CIN1 (19.2%), ten CIN2 (38.5%) and eight CIN3 (30.8%). There were no cases of invasive carcinoma on follow up. Conclusion: The current appropriate management of HIV-positive women in low-resource settings with a diagnosis of ASC-H on cervical smear is colposcopy, despite the costs involved. In the future and if cost-effective in developing nations, use of novel markers may help select which HIV-positive women can be managed conservatively and which ones referred for more active treatment. More research in this regard is warranted.
On the Ontology of Structural Realism  [PDF]
Markus Fischer
Open Journal of Political Science (OJPS) , 2019, DOI: 10.4236/ojps.2019.91008
Abstract: Due to its systemic approach, structural realism (or neorealism) can be subsumed under methodological holism, which takes social phenomena to be wholes that cannot be reduced to their parts. The wholes posited by structural realism are the state and the international structure. Recent developments in the philosophy of social science suggest that methodological holism ought to be limited to causal explanation and complemented by ontological individualism, which requires an account of how social wholes derive from individuals. Structural realism lacks such an account because it takes the state as an empirical given, mistaking for a fact what is really a concept in need of deductive derivation from individuals. To bring the theory methodologically up to date, this essay undertakes such a derivation of the state from individuals, proceeding in the deductive manner of political theory. It thus provides structural realism with a methodologically valid ontology, which, in turn, enables the theory to better defend itself against liberal and constructivist critics who reduce the state to a transient phenomenon.
Discretisation of stochastic control problems for continuous time dynamics with delay
Markus Fischer,Markus Reiss
Mathematics , 2006,
Abstract: As a main step in the numerical solution of control problems in continuous time, the controlled process is approximated by sequences of controlled Markov chains, thus discretising time and space. A new feature in this context is to allow for delay in the dynamics. The existence of an optimal strategy with respect to the cost functional can be guaranteed in the class of relaxed controls. Weak convergence of the approximating extended Markov chains to the original process together with convergence of the associated optimal strategies is established.
Spectral covolatility estimation from noisy observations using local weights
Markus Bibinger,Markus Rei?
Statistics , 2011,
Abstract: We propose localized spectral estimators for the quadratic covariation and the spot covolatility of diffusion processes which are observed discretely with additive observation noise. The eligibility of this approach to lead to an appropriate estimation for time-varying volatilities stems from an asymptotic equivalence of the underlying statistical model to a white noise model with correlation and volatility processes being constant over small intervals. The asymptotic equivalence of the continuous-time and the discrete-time experiments are proved by a construction with linear interpolation in one direction and local means for the other. The new estimator outperforms earlier nonparametric approaches in the considered model. We investigate its finite sample size characteristics in simulations and draw a comparison between the various proposed methods.
The Influence of Surface Energy on the Washing Quality of Filter Cakes  [PDF]
Markus Wilkens, Urs A. Peuker
Advances in Chemical Engineering and Science (ACES) , 2011, DOI: 10.4236/aces.2011.14036
Abstract: The washing of filter cakes, especially the displacement washing, represents an important aspect in science researches and industrial applications. A lot of ongoing researches are focussed on impurities, which are dissolved in the mother liquid (e.g. sodium chloride) and washed out with the identical pure liquid without impurities. The project flushing focuses on systems with two chemically different liquids. The main aim is to exchange an organic solvent by water. This article focuses on the adsorption effects during a washing process with solid systems of different wetting behaviours.
Not All Shrivels Are Created Equal—Morpho-Anatomical and Compositional Characteristics Differ among Different Shrivel Types That Develop during Ripening of Grape (Vitis vinifera L.) Berries  [PDF]
Bhaskar Rao Bondada, Markus Keller
American Journal of Plant Sciences (AJPS) , 2012, DOI: 10.4236/ajps.2012.37105
Abstract: An understanding of physiological disorders associated with ripening of fruits triggered by abiotic stress relies on anatomical and physico-chemical analyses, as it provide insights into their origin and probable causes. The objective of this study was to analyze different ripening disorders of grape (Vitis vinifera L.) berries by dissecting their morpho-anatomy, shriveling nature, and composition. Four well-defined disorders—sunburn, prolonged dehydration (PD), late-season bunch stem necrosis (LBSN), and berry shrivel (BS) were analyzed in field-grown grapevines of the cultivar Cabernet Sauvignon. Early bunch stem necrosis (EBSN) that occurred before ripening was also included in the study. Unlike healthy spherical berries, the pericarp of disordered berries except for sunburn shriveled causing concomitant reductions in fresh weight and volume. The exocarp of PD berries developed well-ordered indentations as distinct from the wrinkles in LBSN berries, whereas BS berries were flaccid with numerous skin folds. The epicuticular wax occurred as upright platelets in all shrivel forms excluding the sun-exposed hemisphere of sunburned berries. A chlorophyllous inflorescence framework persisted in all shrivel forms but in LBSN, wherein the necrotic regions developed tylosis. Unlike the translucent mesocarp of healthy, sunburned, and PD berries, the mesocarp was collapsed in BS and LBSN berries, nevertheless all had well-developed seeds. The composition of healthy berries was optimal, whereas the disordered berries were compositionally distinct from each other, which as a whole differed from the healthy berries. The BS berries had the lowest sugar content, and although sugar concentration was higher in LBSN, sunburned and PD berries, sugar amount per berry was highest in the healthy berries, the same was true for hexoses. Healthy and BS berries exhibited highest amounts of tartaric acid followed by sunburn and PD berries, whereas the LBSN berries had the lowest values. Conversely, healthy and PD berries had the highest amounts of malic acid followed by LBSN, sunburn and BS berries, which collectively displayed similar amounts. The PD berries exhibited the highest calcium content followed by LBSN, healthy, and finally BS and sunburned berries. A linear relationship existed between potassium (K) and pH of the berries. The PD berries had the highest amounts of K followed by healthy, sunburn, LBSN, and BS berries. Overall, the results reported here provided combined morpho-anatomical and compositional analyses of different shrivel types that occurred during
Derivation of Moment Equations for the Theoretical Description of Electrons in Nonthermal Plasmas  [PDF]
Markus M. Becker, Detlef Loffhagen
Advances in Pure Mathematics (APM) , 2013, DOI: 10.4236/apm.2013.33049
Abstract:

The derivation of moment equations for the theoretical description of electrons is of interest for modelling of gas discharge plasmas and semiconductor devices. Usually, certain artificial closure assumptions are applied in order to derive a closed system of moment equations from the electron Boltzmann equation. Here, a novel four-moment model for the description of electrons in nonthermal plasmas is derived by an expansion of the electron velocity distribution function in Legendre polynomials. The proposed system of partial differential equations is consistently closed by definition of transport coefficients that are determined by solving the electron Boltzmann equation and are then used in the fluid calculations as function of the mean electron energy. It is shown that the four-moment model can be simplified to a new drift-diffusion approximation for electrons without loss of accuracy, if the characteristic frequency of the electric field alteration in the discharge is small in comparison with the momentum dissipation frequency of the electrons. Results obtained by the proposed fluid models are compared to those of a conventional drift-diffusion approximation as well as to kinetic results using the example of low pressure argon plasmas. It is shown that the results provided by the new approaches are in good agreement with kinetic results and strongly improve the accuracy of fluid descriptions of gas discharges.

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