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Nitrogen-doped bamboo-shaped carbon nanotubes (N-BCNTs) were produced by catalytic chemical vapor deposition using butylamine as carbon sources. The morphology of the nanotubes and the type of nitrogen incorporation was studied. The surface polarity of the synthetized nanotubes was tuned by using three different oxidizing agents, H2SO4/HNO3 mixture, cc. HNO3, and H2O2. It has been shown that due to the oxidation, the presence of oxygen containing functional groups (–COOH, –OH), and therefore, the hydrophilic character of the N-BCNTs considerably increased. The functionalized N-BCNTs and non-treated CNTs were used as support materials to prepare 5 wt% Pd catalysts. The synthesized Pd nanocomposites were successfully tested in liquid phase heterogeneous hydrogenation (octadecene to octadecane). Although, the catalytic activity decreased by the increasing surface polarity of the nanotubes, which can be attributed to the non-polar reactants, this effect could be beneficial in case of hydrophilic systems.

Background Implanted osmotic minipumps are commonly used for long-term, brain-targeted delivery of a wide range of experimental agents by being connected to a catheter and a cannula. During the stereotactical surgery procedure, the cannula has to be placed correctly in the x-y directions and also with respect to the injection point in the z-direction (deepness). However, the flat fixation base of available cannula holders doesn’t allow an easy, secure fixation onto the curve-shaped skull. New method We have developed a modified method for a better fixation of the cannula holder by using an easy-to-produce, skull-shaped silicone spacer as fixation adapter. Results We describe the application and its fast and reliable production in the lab. Comparison with existing method(s) Superglue or cement is currently being used as the method of choice. However, the curve-shaped skull surface does not fit well with the flat and rigid cannula adapter which leads to fixation problems over time causing wide infusion channels and often also to leakage problems from intracerebrally applied agents towards the surface meninges. As another consequence of the inappropriate fixation, the cannula may loosen from the skull before the end of the experiment or it causes damage to the brain tissue, harming the animals with leading to a failure of the whole experiment. Conclusions The easy-to-produce spacer facilitates the crucial step of long-term, stereotactic brain infusion experiments with intracerebral catheters in a highly secure and reproducible way.

ADA (alteration/deficiency in activation) 3 is a conserved component of several transcriptional adaptor and HAT (histone acetyltransferase) complexes that regulate RNA polymerase IImediated gene expression. Within the HAT complexes ADA3 is associated with ADA2 and the HAT GCN5 (general control non-repressed 5). ADA3 plays roles in diverse cellular processes and also in malignancies by modulating GCN5 catalytic activity and/or by interactions with other regulators. To gain a better understanding of ADA3 function, we used a yeast two-hybrid approach to screen a human fetal cDNA library for proteins that interacted with hADA3 (human ADA3). We identified three novel hADA3-interacting partners, a transcriptional regulator, AATF (apoptosis-antagonizing transcription factor), and regulatory subunits of the PP1 (protein phosphatase 1) and PP2A (protein phosphatase 2A) [PPP1R7 (PP1 regulatory subunit 7) and PPP2R5D (PP2A 56 kDa regulatory subunit δ isoform) respectively]. Analysis of truncated versions of hADA3 indicated that the C-terminal ADA2-interacting domain was not required for these interactions. Fluorescent microscopy analysis and co-immunoprecipitation provided support for the co-localization and interaction of hADA3 with these proteins in human cells. Expression of the interacting proteins altered expression of an hADA3-regulated reporter gene, suggesting functional consequences for the interactions. The detected interactions of hADA3 might extend the spectrum of mechanisms by which ADA3 can contribute to the regulation of gene expression and shed light on processes mediated by these newly identified ADA3 partners. © 2013 Biochemical Society.

Despite inherent limitations, the ease and rapidity of their use make transiently expressed reporter gene assays the most frequently used techniques for analyzing promoters and transcriptional regulators. The results of transient reporter gene assays are generally accepted to reflect transcriptional processes correctly, though these assays study regulatory sequences outside of the chromosomal environment and draw conclusions on transcription based on enzyme activity determination. For transient reporter gene assays, often more than one promoter is introduced into one cell. In addition to the one driving the primary reporter gene expression, a further one might serve to ensure the production of an internal control second reporter or/and a trans-acting factor. We demonstrate here by various examples that interference between physically unlinked promoters can profoundly affect reporter expression. Results of reporter gene assays performed by combinations of the cytomegalovirus promoter and various other promoter constructs (human immunodeficiency virus [HIV], Human T-cell Leukemia Virus Type I (HTLV-I), NF-?B-responsive, and p53-responsive) and trans-activator factors (HIV-Tat and p53) in different host cell lines (U2OS, HeLa, and L929) prove that interference between active transcription units can modify transcription responses dramatically. Since the interference depends on the promoters used, on the amount of transfected DNA, on the host cells, and on other factors, extra caution is required in interpreting results of transient reporter gene assays. © Copyright 2012, Mary Ann Liebert, Inc..

The multidrug-resistant phenotype of tumor cells is acquired via an increased capability of drug efflux by ABC transporters and causes serious problems in cancer treatment. With the aim to uncover whether changes induced by epigenetic mechanisms in the expression level of drug transporter genes correlates with changes in the drug resistance phenotypes of resistant cells, we studied the expression of drug transporters in rat hepatoma cell lines. We found that of the three major rat ABC transporter genes Abcb1a, Abcb1b and Abcc1 the activity of only Abcb1b increased significantly in colchicine-selected, drug-resistant cells. Increased transporter expression in drug-resistant cells results primarily from transcriptional activation. A change in histone modification at the regulatory regions of the chromosomally adjacent Abcb1a and Abcb1b genes differentially affects the levels of corresponding mRNAs. Transcriptional up- and down-regulation accompany an increase in acetylation levels of histone H3 lysine 9 at the promoter regions of Abcb1b and Abcb1a, respectively. Drug efflux activity, however, does not follow tightly the transcriptional activity of drug transporter genes in hepatoma cells. Our results point out the need for careful analysis of cause-and-effect relationships between changes in histone modification, drug transporter expression and drug resistance phenotypes.