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221.
Gregor Leicht Stefan Troschütz Christina Andreou Evangelos Karamatskos Matthias Ertl Dieter Naber Christoph Mulert 《PloS one》2013,8(12)
Background
The processing of reward and punishment stimuli in humans appears to involve brain oscillatory activity of several frequencies, probably each with a distinct function. The exact nature of associations of these electrophysiological measures with impulsive or risk-seeking personality traits is not completely clear. Thus, the aim of the present study was to investigate event-related oscillatory activity during reward processing across a wide spectrum of frequencies, and its associations with impulsivity and sensation seeking in healthy subjects.Methods
During recording of a 32-channel EEG 22 healthy volunteers were characterized with the Barratt Impulsiveness and the Sensation Seeking Scale and performed a computerized two-choice gambling task comprising different feedback options with positive vs. negative valence (gain or loss) and high or low magnitude (5 vs. 25 points).Results
We observed greater increases of amplitudes of the feedback-related negativity and of activity in the theta, alpha and low-beta frequency range following loss feedback and, in contrast, greater increase of activity in the high-beta frequency range following gain feedback. Significant magnitude effects were observed for theta and delta oscillations, indicating greater amplitudes upon feedback concerning large stakes. The theta amplitude changes during loss were negatively correlated with motor impulsivity scores, whereas alpha and low-beta increase upon loss and high-beta increase upon gain were positively correlated with various dimensions of sensation seeking.Conclusions
The findings suggest that the processing of feedback information involves several distinct processes, which are subserved by oscillations of different frequencies and are associated with different personality traits. 相似文献222.
Christine Ellingsen Stefan Walenta Tord Hompland Wolfgang Mueller-Klieser Einar K. Rofstad 《Translational oncology》2013,6(5):607-617
Poor disease-free and overall survival rates in locally advanced cervical cancer are associated with a tumor micro-environment characterized by extensive hypoxia, interstitial hypertension, and high lactate concentrations. The potential of gadolinium diethylenetriamine pentaacetic acid-based dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in assessing the microenvironment and microenvironment-associated aggressiveness of cervical carcinomas was investigated in this preclinical study. CK-160 and TS-415 cervical carcinoma xenografts were used as tumor models. DCE-MRI was carried out at 1.5 T, and parametric images of Ktrans and ve were produced by pharmacokinetic analysis of the DCE-MRI series. Pimonidazole was used as a marker of hypoxia. A Millar catheter was used to measure tumor interstitial fluid pressure (IFP). The concentrations of glucose, adenosine triphosphate (ATP), and lactate were measured by induced metabolic bioluminescence imaging. High incidence of lymph node metastases was associated with high hypoxic fraction and high lactate concentration in CK-160 tumors and with high IFP and high lactate concentration in TS-415 tumors. Low Ktrans was associated with high hypoxic fraction, low glucose concentration, and high lactate concentration in tumors of both lines and with high incidence of metastases in CK-160 tumors. Associations between ve and microenvironmental parameters or metastatic propensity were not detected in any of the tumor lines. Taken together, this preclinical study suggests that Ktrans is a potentially useful biomarker for poor outcome of treatment in advanced cervical carcinoma. The possibility that Ktrans may be used to identify patients with cervical cancer who are likely to benefit from particularly aggressive treatment merits thorough clinical investigations. 相似文献
223.
One of the fundamental interests in neuroscience is to understand the integration of excitatory and inhibitory inputs along the very complex structure of the dendritic tree, which eventually leads to neuronal output of action potentials at the axon. The influence of diverse spatial and temporal parameters of specific synaptic input on neuronal output is currently under investigation, e.g. the distance-dependent attenuation of dendritic inputs, the location-dependent interaction of spatially segregated inputs, the influence of GABAergig inhibition on excitatory integration, linear and non-linear integration modes, and many more.With fast micro-iontophoresis of glutamate and GABA it is possible to precisely investigate the spatial and temporal integration of glutamatergic excitation and GABAergic inhibition. Critical technical requirements are either a triggered fluorescent lamp, light-emitting diode (LED), or a two-photon scanning microscope to visualize dendritic branches without introducing significant photo-damage of the tissue. Furthermore, it is very important to have a micro-iontophoresis amplifier that allows for fast capacitance compensation of high resistance pipettes. Another crucial point is that no transmitter is involuntarily released by the pipette during the experiment.Once established, this technique will give reliable and reproducible signals with a high neurotransmitter and location specificity. Compared to glutamate and GABA uncaging, fast iontophoresis allows using both transmitters at the same time but at very distant locations without limitation to the field of view. There are also advantages compared to focal electrical stimulation of axons: with micro-iontophoresis the location of the input site is definitely known and it is sure that only the neurotransmitter of interest is released. However it has to be considered that with micro-iontophoresis only the postsynapse is activated and presynaptic aspects of neurotransmitter release are not resolved. In this article we demonstrate how to set up micro-iontophoresis in brain slice experiments. 相似文献
224.
Miguel F. Gonzales Teresa Brooks Stefan U. Pukatzki Daniele Provenzano 《Journal of visualized experiments : JoVE》2013,(80)
Electroporation has become a widely used method for rapidly and efficiently introducing foreign DNA into a wide range of cells. Electrotransformation has become the method of choice for introducing DNA into prokaryotes that are not naturally competent. Electroporation is a rapid, efficient, and streamlined transformation method that, in addition to purified DNA and competent bacteria, requires commercially available gene pulse controller and cuvettes. In contrast to the pulsing step, preparation of electrocompetent cells is time consuming and labor intensive involving repeated rounds of centrifugation and washes in decreasing volumes of sterile, cold water, or non-ionic buffers of large volumes of cultures grown to mid-logarithmic phase of growth. Time and effort can be saved by purchasing electrocompetent cells from commercial sources, but the selection is limited to commonly employed E. coli laboratory strains. We are hereby disseminating a rapid and efficient method for preparing electrocompetent E. coli, which has been in use by bacteriology laboratories for some time, can be adapted to V. cholerae and other prokaryotes. While we cannot ascertain whom to credit for developing the original technique, we are hereby making it available to the scientific community. 相似文献
225.
Sakine Simsekyilmaz Fabian Schreiber Stefan Weinandy Felix Gremse Tolga Taha S?nmez Elisa A. Liehn 《Journal of visualized experiments : JoVE》2013,(75)
Despite the considerable progress made in the stent development in the last decades, cardiovascular diseases remain the main cause of death in western countries. Beside the benefits offered by the development of different drug-eluting stents, the coronary revascularization bears also the life-threatening risks of in-stent thrombosis and restenosis. Research on new therapeutic strategies is impaired by the lack of appropriate methods to study stent implantation and restenosis processes. Here, we describe a rapid and accessible procedure of stent implantation in mouse carotid artery, which offers the possibility to study in a convenient way the molecular mechanisms of vessel remodeling and the effects of different drug coatings. 相似文献
226.
Ad Vos Tobias Nolden Christiane Habla Stefan Finke Conrad M. Freuling Jens Teifke Thomas Müller 《European Journal of Wildlife Research》2013,59(5):637-643
Raccoons can be found almost everywhere in Germany since their first successful introduction in 1934. Although the animal is a well-known reservoir species for rabies in the USA, during the last European fox rabies epizootic, only a few rabid raccoons were reported from Germany. In recent years, the raccoon population density has increased tremendously, especially in (semi) urban settings. Presently, Germany is free of terrestrial wildlife rabies. To assess the potential risk that the raccoon population in Germany could act as a reservoir species upon reemergence of rabies, the susceptibility of the local raccoon population was investigated. Wild-caught animals were inoculated with the most likely lyssavirus variants to infect the local population. It was shown that the raccoons were fully susceptible for a dog and raccoon rabies virus isolate. Also, five of six raccoons inoculated with a fox rabies virus isolate showed clinical signs. However, none of the raccoons infected with European Bat Lyssavirus type 1 succumbed to rabies; meanwhile, all these raccoons seroconverted. It is concluded that the highest risk for the raccoon population in Germany to become infected with lyssaviruses is through the importation of rabies infected dogs. 相似文献
227.
Marcus Bär Joachim Klaer Lothar Weinhardt Regan G. Wilks Stefan Krause Monika Blum Wanli Yang Clemens Heske Hans‐Werner Schock 《Liver Transplantation》2013,3(6):777-781
The surface properties of CuInS2 (CIS) thin‐film solar cell absorbers are investigated by a combination of electron and soft X‐ray spectroscopies. Spatially separated regions of varying colors are observed and identified to be dominated by either CuS or Cu2S surface phases. After their removal by KCN etching, the samples cannot be distinguished by eye and the CIS surface is found to be Cu‐deficient in both regions. However, a significantly more pronounced off‐stoichiometry in the region initially covered by Cu2S can be identified. In this region, the resulting surface band gap is also significantly larger than the EgSurf of the initially CuS‐terminated region. Such variations may represent a hidden parameter which, if overlooked, induces irreproducibility and thus prevents systematic optimization efforts. 相似文献
228.
Stefan Hindersin Marco Leupold Martin Kerner Dieter Hanelt 《Bioprocess and biosystems engineering》2013,36(3):345-355
Photosynthetic activity and temperature regulation of microalgal cultures (Chlorella vulgaris and Scenedesmus obliquus) under different irradiances controlled by a solar tracker and different cell densities were studied in outdoor flat panel photobioreactors. An automated process control unit regulated light and temperature as well as pH value and nutrient concentration in the culture medium. CO2 was supplied using flue gas from an attached combined block heat and power station. Photosynthetic activity was determined by pulse amplitude modulation fluorometry. Compared to the horizontal irradiance of 55 mol photons m?2 d?1 on a clear day, the solar tracked photobioreactors enabled a decrease and increase in the overall light absorption from 19 mol photons m?2 d?1 (by rotation out of direct irradiance) to 79 mol photons m?2 d?1 (following the position of the sun). At biomass concentrations below 1.1 g cell dry weight (CDW) L?1, photoinhibition of about 35 % occurred at irradiances of ≥1,000 μmol photons m?2 s?1 photosynthetic active radiation (PAR). Using solar tracked photobioreactors, photoinhibition can be reduced and at optimum biomass concentration (≥2.3 g CDW L?1), the culture was irradiated up to 2,000 μmol photons m?2 s?1 to overcome light limitation with biomass yields of 0.7 g CDW mol photons?1 and high photosynthetic activities indicated by an effective quantum yield of 0.68 and a maximum quantum yield of 0.80 (F v/F m). Overheating due to high irradiance was avoided by turning the PBR out of the sun or using a cooling system, which maintained the temperature close to the species-specific temperature optima. 相似文献
229.
230.
Riho Gross Stefan Palm Kuldar Kõiv Tore Prestegaard Japo Jussila Tiit Paaver Juergen Geist Harri Kokko Anna Karjalainen Lennart Edsman 《Conservation Genetics》2013,14(4):809-821
Noble crayfish (Astacus astacus L.), the most highly valued freshwater crayfish in Europe, is threatened due to a long-term population decline caused mainly by the spread of crayfish plague. Reintroduction of the noble crayfish into restored waters is a common practice but the geographic and genetic origin of stocking material has rarely been considered, partially because previous genetic studies have been hampered by lack of nuclear gene markers with known inheritance. This study represents the first large scale population genetic survey of the noble crayfish (633 adults from 18 locations) based on 10 newly developed microsatellite markers. We focused primarily on the Baltic Sea area (Estonia, Finland and Sweden) where the largest proportion of the remaining populations exists. To allow comparisons, samples from the Black Sea catchment (the Danube drainage) were also included. Two highly differentiated population groups were identified corresponding to the Baltic Sea and the Black Sea catchments, respectively. The Baltic Sea catchment populations had significantly lower genetic variation and private allele numbers than the Black Sea catchment populations. Within the Baltic Sea area, a clear genetic structure was revealed with population samples corresponding well to their geographic origin, suggesting little impact of long-distance translocations. The clear genetic structure strongly suggests that the choice of stocking material for re-introductions and supplemental releases needs to be based on empirical genetic knowledge. 相似文献