University of Marburg

About: University of Marburg is a education organization based out in Marburg, Germany. It is known for research contribution in the topics: Population & Gene. The organization has 23195 authors who have published 42907 publications receiving 1506069 citations. The organization is also known as: Philipps University of Marburg & Philipps-Universität.

Recent advances in rational gene transfer vector design based on poly(ethylene imine) and its derivatives

Abstract: The continually increasing wealth of knowledge about the role of genes involved in acquired or hereditary diseases renders the delivery of regulatory genes or nucleic acids into affected cells a potentially promising strategy. Apart from viral vectors, non-viral gene delivery systems have recently received increasing interest, due to safety concerns associated with insertional mutagenesis of retro-viral vectors. Especially cationic polymers may be particularly attractive for the delivery of nucleic acids, since they allow a vast synthetic modification of their structure enabling the investigation of structure-function relationships. Successful clinical application of synthetic polycations for gene delivery will depend primarily on three factors, namely (1) an enhancement of the transfection efficiency, (2) a reduction in toxicity and (3) an ability of the vectors to overcome numerous biological barriers after systemic or local administration. Among the polycations presently used for gene delivery, poly(ethylene imine), PEI, takes a prominent position, due to its potential for endosomal escape. PEI as well as derivatives of PEI currently under investigation for DNA and RNA delivery will be discussed. This review focuses on structure-function relationships and the physicochemical aspects of polyplexes which influence basic characteristics, such as complex formation, stability or in vitro cytotoxicity, to provide a basis for their application under in vivo conditions. Rational design of optimized polycations is an objective for further research and may provide the basis for a successful cationic polymer-based gene delivery system in the future. Copyright © 2005 John Wiley & Sons, Ltd.

Sub-cycle control of terahertz high-harmonic generation by dynamical Bloch oscillations

Abstract: Terahertz waveforms with peak fields of 72 MV cm−1 and a central frequency of 30 THz drive interband polarization in bulk GaSe off-resonantly and accelerate excited electron–hole pairs, inducing dynamical Bloch oscillations. This results in the emission of phase-stable, high-harmonic transients over the whole frequency range of 0.1–675 THz.

Characterization of DNA sequences through which cadmium and glucocorticoid hormones induce human metallothionein-IIA gene.

Abstract: Deletion experiments have defined two stretches of DNA (genetic elements), lying close to the promoter for a human gene for metallothionein, that separately mediate the induction of the gene by heavy metal ions, particularly cadmium, and by glucocorticoid hormones. The element responsible for induction by cadmium is duplicated, yet a single copy is fully functional; the element responsible for induction by glucocorticoid hormones is coincident with the DNA-binding site for the glucocorticoid hormone receptor.

Depression and cancer mortality: a meta-analysis.

Abstract: BackgroundThe goal of the present study was to analyze associations between depression and mortality of cancer patients and to test whether these associations would vary by study characteristics.MethodMeta-analysis was used for integrating the results of 105 samples derived from 76 prospective studies.ResultsDepression diagnosis and higher levels of depressive symptoms predicted elevated mortality. This was true in studies that assessed depression before cancer diagnosis as well as in studies that assessed depression following cancer diagnosis. Associations between depression and mortality persisted after controlling for confounding medical variables. The depression–mortality association was weaker in studies that had longer intervals between assessments of depression and mortality, in younger samples and in studies that used the Beck Depression Inventory as compared with other depression scales.ConclusionsScreening for depression should be routinely conducted in the cancer treatment setting. Referrals to mental health specialists should be considered. Research is needed on whether the treatment of depression could, beyond enhancing quality of life, extend survival of depressed cancer patients.

Multilabel classification via calibrated label ranking

Abstract: Label ranking studies the problem of learning a mapping from instances to rankings over a predefined set of labels. Hitherto existing approaches to label ranking implicitly operate on an underlying (utility) scale which is not calibrated in the sense that it lacks a natural zero point. We propose a suitable extension of label ranking that incorporates the calibrated scenario and substantially extends the expressive power of these approaches. In particular, our extension suggests a conceptually novel technique for extending the common learning by pairwise comparison approach to the multilabel scenario, a setting previously not being amenable to the pairwise decomposition technique. The key idea of the approach is to introduce an artificial calibration label that, in each example, separates the relevant from the irrelevant labels. We show that this technique can be viewed as a combination of pairwise preference learning and the conventional relevance classification technique, where a separate classifier is trained to predict whether a label is relevant or not. Empirical results in the area of text categorization, image classification and gene analysis underscore the merits of the calibrated model in comparison to state-of-the-art multilabel learning methods.