Synthesis and characterization of copper oxide nanoparticles and investigation of their effects on the vitality and metabolism of astrocytes

Copper oxide nanoparticles (CuO-NPs) recently raised the industryâ s interest due to their interesting chemical and physical properties. The continuous increase of products containing CuO-NPs and the unintentional generation of CuO-NPs by technical processes establish an increased risk of human exposure. Since nanoparticles can reach the brain upon exposure, it is of high interest to evaluate the uptake and potential adverse effects on brain cells. In this context astrocytes are of special interest due to their central role in the brain homeostasis and in defence processes. In the presented thesis, a method for the synthesis of CuO-NPs was established. After a detailed analysis of the physico-chemical properties of the synthesized CuO-NPs, primary astrocytes cultures were exposed to these CuO-NPs. The accumulation and uptake mechanism of CuO-NPs by cultured astrocytes as well as the resulting effects on the cell vitality and metabolism were investigated. It was shown that cultured astrocytes strongly accumulated CuO-NPs in a time-, concentration-, temperature- and media-dependent manner. Results from experiments with pharmacological inhibitors of different endocytotic pathways suggest that clathrin-mediated endocytosis, macropinocytosis and the recycling of membranes are involved in the uptake of CuO-NPs by astrocytes. Accumulated CuO-NPs exerted a strong toxicity when the specific cellular copper contents reached values above 10 nmol copper per mg protein. The mechanism of toxicity was assigned to a strong increase in reactive oxygen species in the treated cells. Cultured astrocytes treated with subtoxic concentrations of CuO-NPs over a time period of 24 h strongly increased their gycolytic flux, their glutathione content as well as the levels of the copper storage protein metallothioneine. The observed increase in glycolytic flux and metallothioneine levels was prevented in presence of the cell permeable copper chelator tetrathiomolybdate. This chelator was also capable of preventing the strong toxicity and the increased generation of reactive oxygen species in acute exposure scenarios where high concentrations of CuO-NPs were applied to cultured astrocytes. Similarly, toxicity observed after the exposure of cultured astrocytes with CuCl2 was prevented by copper chelators while copper reducing antioxidants increased copper uptake and copper derived toxicity. The data presented in this thesis reveal that CuO-NPs can have severe deleterious effects on astrocytes, which otherwise are very robust against several toxins. The vulnerability of astrocytes to CuO-NPs suggests that brain cells may be severely damaged if they encounter such nanoparticles. Hence, the exposure of humans to CuO-NPs should be minimized and carefully evaluated to prevent potential health hazards

3D Experimental investigation of the hygro-mechanical behaviour of wood at cellular and sub-cellular scale: detection of local deformations

The swelling/shrinkage of spruce wood samples (Picea Abies) is documented with high resolution XRay Tomography and advanced image analysis tools. We report the reversible moisture-induced global and local deformations at the cellular and sub-cellular scales. In particular, we present sophisticated methods for detecting local deformations in the cell wall. Insight is given on the hygromechanical behaviour of wood cell material and on the role of ultra-cellular components in wood, such as bordered pits and rays

Dealing with deontic modality in a termbase: the case of Dutch and Spanish legal language

In this article, we analyse, on the basis of comparable corpora (Dutch-Spanish) of the same legal genre, that is, the Articles of Association, an aspect of cross-linguistic variation, namely the expression of deontic modality. We also examine the ways in which the findings of the study can be processed into a bilingual, translator-friendly legal termbase (JuriGenT). In doing so, we map out the asymmetry, which is mainly attributable to the use of tenses, and duly process this in the relevant term records, taking the view that the translator should be aware of the similarities and differences of their usage so as to be able to make well-considered translation decisions

Simulation of between repeat variability in real time PCR reactions

While many decisions rely on real time quantitative PCR (qPCR) analysis few attempts have hitherto been made to quantify bounds of precision accounting for the various sources of variation involved in the measurement process. Besides influences of more obvious factors such as camera noise and pipetting variation, changing efficiencies within and between reactions affect PCR results to a degree which is not fully recognized. Here, we develop a statistical framework that models measurement error and other sources of variation as they contribute to fluorescence observations during the amplification process and to derived parameter estimates. Evaluation of reproducibility is then based on simulations capable of generating realistic variation patterns. To this end, we start from a relatively simple statistical model for the evolution of efficiency in a single PCR reaction and introduce additional error components, one at a time, to arrive at stochastic data generation capable of simulating the variation patterns witnessed in repeated reactions (technical repeats). Most of the variation in C-q values was adequately captured by the statistical model in terms of foreseen components. To recreate the dispersion of the repeats' plateau levels while keeping the other aspects of the PCR curves within realistic bounds, additional sources of reagent consumption (side reactions) enter into the model. Once an adequate data generating model is available, simulations can serve to evaluate various aspects of PCR under the assumptions of the model and beyond