1,721,559 research outputs found
Activating ras mutations fail to ensure efficient replication of adenovirus mutants lacking VA-RNA
No full textAdenoviruses lacking their PKR-antagonizing VA RNAs replicate poorly in primary cells. It has been suggested that these virus recombinants still replicate efficiently in tumor cells with Ras mutations and might therefore be useful in tumor therapy. The ability of interferon-sensitive viruses to grow in Ras-mutant tumor cells is generally ascribed to a postulated inhibitory effect of mutant Ras on PKR. We have constructed a set of isogenic adenoviruses that lack either or both VA RNA species, and tested virus replication in a variety of cell species with different Ras status. In tendency, VA-less viruses replicated with higher efficiency in Ras-mutant cells, as compared to cell lines without Ras mutation. However, several exceptions to this rule were observed, arguing against a direct inhibition of PKR by mutant Ras. Phosphorylation of the PKR-substrate elF2 alpha was observed regardless of the Ras mutational status, upon infection with VA-less adenoviruses in the presence of interferon, but also upon addition of the PKR activator polyIC to cells. When comparing two isogenic cell lines that differ solely with regard to the presence or absence of mutant Ras, no difference was observed concerning the replication of VA-less adenoviruses or the phosphorylation of elF2 alpha. We conclude that mutant Ras does not directly affect elF2 alpha phosphorylation or the replication of interferon-sensitive adenoviruses. These results strongly suggest that the Ras mutational status is insufficient to predict the oncolytic effect of interferon-sensitive viruses. We propose that Ras mutations predispose tumor cells to undergo secondary changes that sometimes enable the replication of interferon-sensitive viruses
Evaluation of an attract and kill strategy for western corn rootworm larvae
No full textSchumann M, Patel A, Vidal S. Evaluation of an attract and kill strategy for western corn rootworm larvae. Applied Soil Ecology. 2013;2013(64):178-189.Western corn rootworm larvae are serious soil dwelling maize pests, and use carbon dioxide (CO2) to
locate maize roots. The efficacy of insecticides can be enhanced by a combination with an attractant
used in host finding, known as attract and kill. This study tested the use of CO2 emitting capsules as an
attractant in combination with the soil insecticide tefluthrin. An observation device was developed to
study the temporal and spatial distribution changes of the larvae and to test whether these are influenced
by the application of the capsules. Furthermore it was evaluated to what extent larvae are killed by the
insecticide in combination with the capsules and whether this could be used for an attract and kill strategy
to manage this pest.
The observation device enabled recovery of 20–40% of the inserted larvae. The spatial analysis of distance
indices revealed a sequence of spatial and temporal distribution patterns of the larvae in the root
system. This sequence of spatial distributionwasdisrupted by an application of the capsules around which
the larvae started to aggregate. Up to 40% mortality of the larvae with attract and kill was observed and
thus could be increased over the conventional application (11% mortality) at lower application rates of
tefluthrin. In conclusion an attract and kill strategy might be valuable to target this soil dwelling pest.
Experiments under field conditions are needed to explore its potential as a management option for the
western corn rootworm. Moreover, a further development of the capsules with host specific cues is
needed to increase the attractiveness and subsequent mortality of the larvae
Adenovirus-induced extracellular signal-regulated kinase phosphorylation during the late phase of infection enhances viral protein levels and virus progeny
No full textThe Raf/mitogen-activated protein/extracellular signal-regulated kinase (ERK) kinase (MEK)/ERK signaling cascade enhances tumor cell proliferation in many cases. Here, we show that adenovirus type 5, a small DNA tumor virus used in experimental cancer therapy, strongly induces ERK phosphorylation during the late phase of infection. Pharmacologic inhibition of ERK phosphorylation reduced virus recovery by > 100-fold. Blocking MEK/ERK signaling affected virus DNA replication and mRNA levels only weakly but strongly reduced the amount of viral proteins, independently of the kinases MNK1 and PKR. Hence, adenovirus induces the oncogenic Raf/MEK/ERK signaling pathway to enhance viral progeny by sustaining the levels of viral proteins. Concerning therapy, our results suggest that the use of Raf/MEK/ERK inhibitors will interfere with the propagation of oncolytic adenoviruses
Data mining feature selection for credit scoring models
No full textThe features used may have an important effect on the performance of credit scoring models. The process of choosing the best set of features for credit scoring models is usually unsystematic and dominated by somewhat arbitrary trial. This paper presents an empirical study of four machine learning feature selection methods. These methods provide an automatic data mining technique for reducing the feature space. The study illustrates how four feature selection methods -'ReliefF','Correlation-based', 'Consistency-based' and 'Wrapper' algorithms help to improve three aspects of the performance of scoring models: model simplicity, model speed and model accuracy. The experiments are conducted on real data sets using four classification algorithms -'model tree (M5)', 'neural network (multi-layer perceptron with back-propagation)', 'logistic regression', and 'k-nearest-neighbours'
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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