TiO2 nanotube composite layers as delivery system for ZnO and Ag nanoparticles - an unexpected overdose effect decreasing their antibacterial efficacy

Enhancement of biocompatibility and antibacterial properties of implant materials is potentially beneficial for their practical value. Therefore, the use of metallic and metallic oxide nanoparticles as antimicrobial coatings components which induce minimized antibacterial resistance receives currently particular attention. In this work, TiO2 nanotubes layers loaded with ZnO and Ag nanoparticles were designed for biomedical coatings and delivery systems and evaluated for antimicrobial activity. TiO2 nanotubes themselves exhibited considerable and diameter-dependent antibacterial activity against planktonic Staphylococcus epidermidis cells but favored bacterial adhesion. Loading of nanotubes with moderate amount of ZnO nanoparticles significantly diminished S. epidermidis cell adhesion and viability just after 1.5h contact with modified surfaces. However, an increase of loaded ZnO amount unexpectedly altered the structure of nanoparticle-nanolayer, caused partial closure of nanotube interior and significantly reduced ZnO solubility and antibacterial efficacy. Co-deposition of Ag nanoparticles enhanced the antibacterial properties of synthesized coatings. However, the increase of ZnO quantity on Ag nanoparticles co-deposited surfaces favored the adhesion of bacterial cells. Thus, ZnO/Ag/TiO2 nanotube composite layers may be promising delivery systems for combating post-operative infections in hard tissue replacement procedures. However, the amount of loaded antibacterial agents must be carefully balanced to avoid the overdose and reduced efficacy.

Physical rehabilitation and risk of atherosclerosis after successful kidney transplantation

Regular physical activity is usually associated with significant health benefits, but therapeutic exercise is seldom routine in renal transplant recipients. We report a randomized clinical trial of exercise training after renal transplantation. Sixty-nine patients were randomly recruited on the first or second day after kidney transplantation into two groups: exercise intervention (PT) and standard care (CT) as controls. The exercise training program consisted of tailored exercises to be performed under a physiotherapist's supervision for 15 to 30 minutes every second hospital day. At that time, biochemical markers of graft function were assessed including specific tests for atherosclerosis. Repeated measures analysis of variance was performed to determine differences between the two groups. We found an inverse correlation between total homocysteine as well as interleukin-18 (IL:18) levels and muscle strength of the upper limbs (r = -.78, P < .0001). There was a positive correlation between muscle strength and improved graft function in the PT group versus CT groups (r = .05; P < .05). Hyperhomocysteinemia and high IL-18 expression in renal allograft recipients may be independent markers of early atherosclerosis development.

Changes in fMRI BOLD response to increasing and decreasing task difficulty during auditory perception of temporal order

We have discovered changes in brain activation during difficult and easy milliseconds timing. Structures engaged in difficult and easier auditory temporal-order judgment were identified in 17 young healthy listeners presented with paired-white-noises of different durations. Within each pair, a short (10 ms) and a long (50 ms) noise was separated by a silent gap of 10, 60 or 160 ms, corresponding to three levels of task difficulty, i.e. difficult, moderate and easy conditions, respectively. A block design paradigm was applied. In temporal-order judgment task subjects were required to define the order of noises within each pair, i.e. short-long or long-short. In the control task they only detected the presentation of the stimulus pair. A multiple regression with 'task difficulty' as a regressor ('difficult', 'moderate', 'easy') showed dynamic changes in neural activity. Increasing activations accompanying increased task difficulty were found in both bilateral inferior parietal lobuli and inferior frontal gyri, thus, in classic regions related to attentional and working memory processes. Conversely, decreased task difficulty was accompanied by increasing involvement of more specific timing areas, namely bilateral medial frontal gyri and left cerebellum. These findings strongly suggest engagement of different neural networks in difficult or easier timing and indicate a framework for understanding timing representation in the brain.

A novel hybrid nanofibrous strategy to target progenitor cells for cost-effective in situ angiogenesis

Ti-doped calcium phosphate ormoglasses combined with biodegradable PLA promote an efficient and low-cost angiogenesis by the generation of high Ca²⁺concentrated interfaces that induce a high yield of tubulogenesis, with the gain in interface–cell interaction and instructivity.

Functional characterization of the cnidarian antiviral immune response reveals ancestral complexity

Animals evolved a broad repertoire of innate immune sensors and downstream effector cascades for defense against RNA viruses. Yet, this system varies greatly among different bilaterian animals, masking its ancestral state. In this study, we aimed to characterize the antiviral immune response of the cnidarian Nematostella vectensis and decipher the function of the retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs) known to detect viral double-stranded RNA (dsRNA) in bilaterians but activate different antiviral pathways in vertebrates and nematodes. We show that polyinosinic:polycytidylic acid (poly(I:C)), a mimic of long viral dsRNA and a primary ligand for the vertebrate RLR melanoma differentiation-associated protein 5 (MDA5), triggers a complex antiviral immune response bearing features distinctive for both vertebrate and invertebrate systems. Importantly, a well-characterized agonist of the vertebrate RIG-I receptor does not induce a significant transcriptomic response that bears signature of the antiviral immune response, which experimentally supports the results of a phylogenetic analysis indicating clustering of the two N. vectensis RLR paralogs (NveRLRa and NveRLRb) with MDA5. Furthermore, the results of affinity assays reveal that NveRLRb binds poly(I:C) and long dsRNA and its knockdown impairs the expression of putative downstream effector genes including RNA interference components. Our study provides for the first time the functional evidence for the conserved role of RLRs in initiating immune response to dsRNA that originated before the cnidarian–bilaterian split and lay a strong foundation for future research on the evolution of the immune responses to RNA viruses.

Towards 4th generation biomaterials: a covalent hybrid polymer-ormoglass architecture

Hybrid materials are being extensively investigated with the aim of mimicking the ECM microenvironment to develop effective solutions for bone tissue engineering. However, the common drawbacks of a hybrid material are the lack of interactions between the scaffold's constituents and the masking of its bioactive phase. Conventional hybrids often degrade in a non-homogeneous manner and the biological response is far from optimal. We have developed a novel material with strong interactions between constituents. The bioactive phase is directly exposed on its surface mimicking the structure of the ECM of bone. Here, polylactic acid electrospun fibers have been successfully and reproducibly coated with a bioactive organically modified glass (ormoglass, Si-Ca-P2 system) covalently. In comparison with the pure polymeric mats, the fibers obtained showed improved hydrophilicity and mechanical properties, bioactive ion release, exhibited a nanoroughness and enabled good cell adhesion and spreading after just one day of culture (rMSCs and rEPCs). The fibers were coated with different ormoglass compositions to tailor their surface properties (roughness, stiffness, and morphology) by modifying the experimental parameters. Knowing that cells modulate their behavior according to the exposed physical and chemical signals, the development of this instructive material is a valuable advance in the design of functional regenerative biomaterials.

Micro and macroevolution of sea anemone venom phenotype

Venom is a complex trait with substantial inter- and intraspecific variability resulting from strong selective pressures acting on the expression of many toxic proteins. However, understanding the processes underlying toxin expression dynamics that determine the venom phenotype remains unresolved. By interspecific comparisons we reveal that toxin expression in sea anemones evolves rapidly and that in each species different toxin family dictates the venom phenotype by massive gene duplication events. In-depth analysis of the sea anemone, Nematostella vectensis, revealed striking variation of the dominant toxin (Nv1) diploid copy number across populations (1-24 copies) resulting from independent expansion/contraction events, which generate distinct haplotypes. Nv1 copy number correlates with expression at both the transcript and protein levels with one population having a near-complete loss of Nv1 production. Finally, we establish the dominant toxin hypothesis which incorporates observations in other venomous lineages that animals have convergently evolved a similar strategy in shaping their venom.

Unravelling the developmental and functional significance of an ancient Argonaute duplication

MicroRNAs (miRNAs) base-pair to messenger RNA targets and guide Argonaute proteins to mediate their silencing. This target regulation is considered crucial for animal physiology and development. However, this notion is based exclusively on studies in bilaterians, which comprise almost all lab model animals. To fill this phylogenetic gap, we characterize the functions of two Argonaute paralogs in the sea anemone Nematostella vectensis of the phylum Cnidaria, which is separated from bilaterians by ~600 million years. Using genetic manipulations, Argonaute-immunoprecipitations and high-throughput sequencing, we provide experimental evidence for the developmental importance of miRNAs in a non-bilaterian animal. Additionally, we uncover unexpected differential distribution of distinct miRNAs between the two Argonautes and the ability of one of them to load additional types of small RNAs. This enables us to postulate a novel model for evolution of miRNA precursors in sea anemones and their relatives, revealing alternative trajectories for metazoan miRNA evolution.

Functional characterization of a 'plant-like' HYL1 homolog in the cnidarian Nematostella vectensis indicates a conserved involvement in microRNA biogenesis

While the biogenesis of microRNAs (miRNAs) in both animals and plants depends on the RNase III Dicer, its partner proteins are considered distinct for each kingdom. Nevertheless, recent discovery of homologs of Hyponastic Leaves1 (HYL1), a ‘plant-specific’ Dicer partner, in the metazoan phylum Cnidaria, challenges the view that miRNAs evolved convergently in animals and plants. Here, we show that the HYL1 homolog Hyl1-like a (Hyl1La) is crucial for development and miRNA biogenesis in the cnidarian model Nematostella vectensis. Inhibition of Hyl1La by morpholinos resulted in metamorphosis arrest in Nematostella embryos and a significant reduction in levels of most miRNAs. Further, meta-analysis of morphants of miRNA biogenesis components, like Dicer1, shows clustering of their miRNA profiles with Hyl1La morphants. Strikingly, immunoprecipitation of Hyl1La followed by quantitative PCR revealed that in contrast to the plant HYL1, Hyl1La interacts only with precursor miRNAs and not with primary miRNAs. This was complemented by an in vitro binding assay of Hyl1La to synthetic precursor miRNA. Altogether, these results suggest that the last common ancestor of animals and plants carried a HYL1 homolog that took essential part in miRNA biogenesis and indicate early emergence of the miRNA system before plants and animals separated.

In both animals and plants, small molecules known as micro ribonucleic acids (or miRNAs for short) control the amount of proteins cells make from instructions encoded in their DNA. Cells make mature miRNA molecules by cutting and modifying newly-made RNA molecules in two stages.

Some of the components animals and plants utilize to make and use miRNAs are similar, but most are completely different. For example, in plants an enzyme known as Dicer cuts newly made RNAs into mature miRNAs with the help of a protein called HYL1, whereas humans and other animals do not have HYL1 and Dicer works with alternative partner proteins, instead. Therefore, it is generally believed that miRNAs evolved separately in animals and plants after they split from a common ancestor around 1.6 billion years ago.

Recent studies on sea anemones and other primitive animals challenge this idea. Proteins similar to HYL1 in plants have been discovered in sea anemones and sponges, and sea anemone miRNAs show several similarities to plant miRNAs including their mode of action. However, it is not clear whether these HYL1-like proteins work in the same way as their plant counterparts.

Here, Tripathi, Admoni et al. investigated the role of the HYL1-like protein in sea anemones. The experiments found that this protein was essential for the sea anemones to make miRNAs and to grow and develop properly. Unlike HYL1 in plants – which is involved in both stages of processing newly-made miRNAs into mature miRNAs – the sea anemone HYL1-like protein only helped in the second stage to make mature miRNAs from intermediate molecules known as precursor miRNAs.

These findings demonstrate that some of the components plants use to make miRNAs also perform similar roles in sea anemones. This suggests that the miRNA system evolved before the ancestors of plants and animals separated from each other. Questions for future studies will include investigating how plants and animals evolved different miRNA machinery, and why sponges and jellyfish have HYL1-like proteins, whereas humans and other more complex animals do not.

The effect of high molecular weight dextran sulfate on the production of interleukin-8 in monocyte cell culture

It has been demonstrated that high molecular weight dextran sulfate (HMDS) is involved in the activation of immune cells. We have shown that HMDS increases the concentration of interleukin (IL)-8 in the medium of monocyte cell culture, in a dose-dependent fashion, whereas under the same conditions, low molecular weight dextran sulfate (LMDS) does not exhibit any effect on IL-8 biosynthesis. The effect of HMDS on IL-8 production is additive to that of IL-1beta and tumor necrosis factor-a (TNFalpha). Flow cytometric analysis revealed the biosynthesis of IL-8 in monocytes incubated in the presence of the HMDS. We hereby postulate that HMDS induces IL-8 biosynthesis in monocyte cell culture.

Towards electrophysiological correlates of auditory perception of temporal order

Recent studies have postulated that the temporal order (TO) of two successive events can be correctly identified if they are separated by an inter-stimulus interval (ISI) of at least 30 ms duration. Using Auditory Evoked Potentials, we tested 21 students for the cortical activation associated with TO detection of two successively presented tones in either 'easy' (ISI=60 ms) or 'difficult' (ISI=10 ms) conditions. The amplitude of P2 component was related to difficulty of TO perception and was significantly higher in 'difficult' than 'easy' condition. Moreover, in 'difficult' condition the correlation analyses revealed a negative association at both Fz and Cz electrodes between P2 amplitudes and the correctness level. Correct responses in this condition were accompanied by lower P2 amplitudes than the incorrect ones.

Morphology and chemical characterization of Ti surfaces modified for biomedical applications

The aim of the present work is to characterize in detail the chemical composition and morphology of titanium surfaces subjected to various environments. Modifications consisted of exposure of Ti to acidic, alkaline or polymer solutions. Such modifications result in chemical and/or morphological changes in the Ti surface. Special attention has been given to identifying the factors influencing cell adhesion and growth. SEM examinations provided morphological characterization of the Ti samples. Surface analytical techniques such as AES or XPS combined with Ar(+) ion sputtering allowed examination of the chemical properties of the Ti surface after chemical pretreatments and investigating the chemical composition of the Ti oxide layer. Raman spectroscopy investigations allowed determination of the crystalline phases of the Ti-oxide layers and characterization of the dextran-modified surface. The results show large differences in the morphology of Ti pretreated with different procedures whereas only minor differences in the chemistry of the surfaces were found. High-resolution Auger investigations have revealed that all the chemical modifications of Ti surfaces resulted in the formation of a titanium oxide layer. XPS confirmed that TiO(2) is the main component of the chemically modified Ti surface. The Raman spectroscopy investigations showed that the titanium surface with a dextran coating is rich in hydroxyl groups. All the surfaces investigated exhibit a hydrophilic character. The possible influence of various surface features on surface biocompatibility is discussed.

Microstructure evolution in age-hardenable aluminium alloy during processing by hydrostatic extrusion

In the present work, scanning and transmission electron microscopy were used to investigate the microstructural evolution occurring during the hydrostatic extrusion of an age-hardenable aluminium alloy. It was shown that processing by hydrostatic extrusion leads to grain refinement to 95 nm in equivalent diameter. Hydrostatic extrusion also influences the geometrical parameters of two different types of particle: intermetallic inclusions and precipitates. The intermetallic inclusions slightly decrease in mean equivalent diameter, but their size remains at the micrometre level. The precipitates are fragmented to nanoscale spherical particles, and their evolution delays the process of grain refinement.

TATA Binding Protein (TBP) Promoter Drives Ubiquitous Expression of Marker Transgene in the Adult Sea Anemone Nematostella vectensis

Nematostella vectensis has emerged as one as the most established models of the phylum Cnidaria (sea anemones, corals, hydroids and jellyfish) for studying animal evolution. The availability of a reference genome and the relative ease of culturing and genetically manipulating this organism make it an attractive model for addressing questions regarding the evolution of venom, development, regeneration and other interesting understudied questions. We and others have previously reported the use of tissue-specific promoters for investigating the function of a tissue or a cell type of interest in vivo. However, to our knowledge, genetic regulators at the whole organism level have not been reported yet. Here we report the identification and utilization of a ubiquitous promoter to drive a wide and robust expression of the fluorescent protein mCherry. We generated animals containing a TATA binding protein (TBP) promoter upstream of the mCherry gene. Flow cytometry and fluorescent microscopy revealed expression of mCherry in diverse cell types, accounting for more than 90% of adult animal cells. Furthermore, we detected a stable mCherry expression at different life stages and throughout generations. This tool will expand the existing experimental toolbox to facilitate genetic engineering and functional studies at the whole organism level.

Microstructure investigations of dental composite samples prepared by focused ion beam technique

In this study, microstructures of dental composites were observed using high resolution scanning transmission electron microscopy (HR STEM). Samples for these observations were prepared by focused ion beam system. Two kinds of dental composites were investigated: (1) polymer-ceramic composite containing nano-sized ceramic fillers and (2) ceramic-polymer composite based on the nano-structured yttrium stabilized zirconia. The first composite is a popular material for dental fillings whereas the second is used for the fabrication of fixed partial dentures. The results are discussed in terms of the evaluation of fabrication process of the composites.