Amplify-and-Forward Relaying in Two-Hop Diffusion-Based Molecular Communication Networks

This paper studies a three-node network in which an intermediate nano-transceiver, acting as a relay, is placed between a nano-transmitter and a nano-receiver to improve the range of diffusion-based molecular communication. Motivated by the relaying protocols used in traditional wireless communication systems, we study amplify-and-forward (AF) relaying with fixed and variable amplification factor for use in molecular communication systems. To this end, we derive a closed-form expression for the expected end-to-end error probability. Furthermore, we derive a closed-form expression for the optimal amplification factor at the relay node for minimization of an approximation of the expected error probability of the network. Our analytical and simulation results show the potential of AF relaying to improve the overall performance of nano-networks.Comment: 7 pages, 6 figures, 1 table. Submitted to the 2015 IEEE Global Communications Conference (GLOBECOM) on April 15, 201

Bacterial diets are able to modulate life-history treats in C. elegans models of neurodegenerative diseases

As life expectancy increase, age-related disorders, such us neurodegenerative diseases (ND), have become more prevalent. Moreover, treatments only attenuate some symptoms, but fail to arrest characteristic neuronal proteotoxicity. Thus, new challenges emerge to science in order to understand molecular basis of these disorders. Lately, the gut-brain axis has gain attention and a close relation between gut microorganism and ND has been proposed. The aim of our work was to evaluate the relevance of the microbiota in the progression of proteotoxic-based disorders, assessing the impact of six non-pathogenic bacterial diets on life-history traits in C. elegans models of ND (vs standard OP50). In a first approach, we found 2 bacteria, Escherichia coli K12 and E. coli HB101, able to improve locomotion in liquid media, in worm’s model of Parkinson disease (PD) at adult day 4, versus E. coli OP50. Moreover, an age-dependent locomotion improvement, between larva-L4 and adult day 4, was observed in solid media after feeding PD model´s worms with 4 different bacteria versus E. coli OP50. We also observed an increase in the developmental timing of wild-type worms grown in 4 bacteria versus E. coli OP50, but more interesting was the accelerated developmental rate selectively found in models of PD and Huntington disease feed with E. coli BL21 (DE3). We are currently evaluating aggregate numbers, lifespan and mitochondrial morphology among others. Our results allowed us to identify bacteria with the ability to drive physiological outcomes and improve health status of C. elegans models of neurodegenerative diseases.Fil: Veuthey, Tania Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; ArgentinaFil: Burkovski, Andras. Universitat Erlangen-nurnberg. Faculty Of Sciences.; Alemania24th International C. elegans ConferenceGlasgowReino UnidoGenetics Society of Americ

Electrochemical Disinfection of Root Canals Bears No Risk of Damaging Periapical Tissues in a Dog Model

Boron-doped diamond (BDD) electrodes have been advocated as a potential treatment alternative to the established methods for root canal disinfection. As healing of periapical tissue is important in this context, the associated risk of host tissue damage was to be evaluated. Following in vitro cell culture experiments (HeLa cells), root canal treatment was performed in an animal trial comparing BDD electrode application and the currently used rinsing media with respect to cell viability and host tissue damage. Statistical analyses comparing the size of radiolucency were based on Kruskal-Wallis and Nemenyi’s All Pairs tests (α = 0.05). The direct application of BDD electrodes had a time-dependent effect on cell viability comparable to H2O2 , NaOCl, and CHX application. In contrast to the chemical treatment, the effect of BDD electrodes was transient. Conventionally treated teeth and teeth additionally treated with BDD electrodes did not significantly differ from each other with respect to the size of the periapical radiolucency as observed radiographically (vertical p = 0.998 and horizontal p = 0.878) and histologically (vertical p = 0.940 and horizontal p = 0.862). While showing greater disinfection efficiency, the application of BDD electrodes for the electrochemical disinfection of root canals does not have a greater risk of host tissue damage compared to the conventional treatment

Pathogene Corynebakterien: erfolgreiche Kolonisierer von Mensch und Tier

The interaction of Corynebacterium diphtheriae and closely related species with host cells is much more complex than originally thought when these bacteria were considered as extracellular pathogens. Host-pathogen interaction studies revealed a wide range of virulence factors contributing to adhesion, invasion, and host cell damage to varying degrees. In combination, these factors lead to the successful colonization of host systems

Electrochemical Disinfection of Dental Implants Experimentally Contaminated with Microorganisms as a Model for Periimplantitis

Despite several methods having been described for disinfecting implants affected by periimplantitis, none of these are universally effective and may even alter surfaces and mechanical properties of implants. Boron-doped diamond (BDD) electrodes were fabricated from niobium wires and assembled as a single instrument for implant cleaning. Chemo-mechanical debridement and air abrasion were used as control methods. Different mono-species biofilms, formed by bacteria and yeasts, were allowed to develop in rich medium at 37 ◦C for three days. In addition, natural multi-species biofilms were treated. Implants were placed in silicone, polyurethane foam and bovine ribs for simulating different clinical conditions. Following treatment, the implants were rolled on blood agar plates, which were subsequently incubated at 37 ◦C and microbial growth was analyzed. Complete electrochemical disinfection of implant surfaces was achieved with a maximum treatment time of 20 min for Candida albicans, Candida dubliniensis, Enterococcus faecalis, Roseomonas mucosa, Staphylococcus epidermidis and Streptococcus sanguinis, while in case of spore-forming Bacillus pumilus and Bacillus subtilis, a number of colonies appeared after BDD electrode treatment indicating an incomplete disinfection. Independent of the species tested, complete disinfection was never achieved when conventional techniques were used. During treatment with BDD electrodes, only minor changes in temperature and pH value were observed. The instrument used here requires optimization so that higher charge quantities can be applied in shorter treatment timesITI Foundation, Switzerlan

A proteomic study of Corynebacterium glutamicum AAA+ protease FtsH

BACKGROUND: The influence of the membrane-bound AAA+ protease FtsH on membrane and cytoplasmic proteins of Corynebacterium glutamicum was investigated in this study. For the analysis of the membrane fraction, anion exchange chromatography was combined with SDS-PAGE, while the cytoplasmic protein fraction was studied by conventional two-dimensional gel electrophoresis. RESULTS: In contrast to the situation in other bacteria, deletion of C. glutamicum ftsH has no significant effect on growth in standard minimal medium or response to heat or osmotic stress. On the proteome level, deletion of the ftsH gene resulted in a strong increase of ten cytoplasmic and membrane proteins, namely biotin carboxylase/biotin carboxyl carrier protein (accBC), glyceraldehyde-3-phosphate dehydrogenase (gap), homocysteine methyltransferase (metE), malate synthase (aceB), isocitrate lyase (aceA), a conserved hypothetical protein (NCgl1985), succinate dehydrogenase A (sdhA), succinate dehydrogenase B (sdhB), succinate dehydrogenase CD (sdhCD), and glutamate binding protein (gluB), while 38 cytoplasmic and membrane-associated proteins showed a decreased abundance. The decreasing amount of succinate dehydrogenase A (sdhA) in the cytoplasmic fraction of the ftsH mutant compared to the wild type and its increasing abundance in the membrane fraction indicates that FtsH might be involved in the cleavage of a membrane anchor of this membrane-associated protein and by this changes its localization. CONCLUSION: The data obtained hint to an involvement of C. glutamicum FtsH protease mainly in regulation of energy and carbon metabolism, while the protease is not involved in stress response, as found in other bacteria

DNA binding by Corynebacterium glutamicum TetR-type transcription regulator AmtR

<p>Abstract</p> <p>Background</p> <p>The TetR family member AmtR is the central regulator of nitrogen starvation response in <it>Corynebacterium glutamicum</it>. While the AmtR regulon was physiologically characterized in great detail up to now, mechanistic questions of AmtR binding were not addressed. This study presents a characterization of functionally important amino acids in the DNA binding domain of AmtR and of crucial nucleotides in the AmtR recognition motif.</p> <p>Results</p> <p>Site-directed mutagenesis, the characterization of corresponding mutant proteins by gel retardation assays and surface plasmon resonance and molecular modelling revealed several amino acids, which are directly involved in DNA binding, while others have more structural function. Furthermore, we could show that the spacing of the binding motif half sites is crucial for repression of transcription by AmtR.</p> <p>Conclusion</p> <p>Although the DNA binding domain of TetR-type repressors is highly conserved and a core binding motif was identified for AmtR and TetR(D), the AmtR binding domain shows individual properties compared to other TetR proteins. Besides by distinct amino acids of AmtR, DNA binding is influenced by nucleotides not only of the conserved binding motif but also by spacing nucleotides in <it>C. glutamicum</it>.</p

Pilot study on the applicability of boron-doped diamond electrodes for tooth whitening

Objectives While various approaches are available for tooth whitening, the basic concept employs the use of peroxides in the form of gels, which are applied to tooth surfaces. Previous studies have shown that reactive oxygen species acting as potent disinfectants can be produced using boron-doped diamond (BDD) electrodes for the electrolysis of water. With these electrodes being applicable, for example, for endodontic treatment, it was the goal of this pilot study to use such electrodes for tooth whitening. Material and Methods Two groups (n = 10) of intact clinical crowns were obtained by horizontally cutting off roots of extracted human teeth. The crowns were either bleached by applying a commercially available agent based on 40% hydrogen peroxide or were immersed in saline undergoing electrolysis with BDD electrodes. Whitening of specimens was judged on standardized photographs by examiners with three different levels of experience. Statistical analysis was based on Gwet's AC2 coefficient with quadratic weights, Shapiro–Wilk tests, and two-way analysis of variance of aligned rank transformed data (level of significance set at α = .05). Results Levels of reliability ranging from fair to substantial were recorded for single persons while the level of reliability ranged between fair and moderate for groups of raters. The level of experience had no significant effect on the ratings (p = .2500). The bleaching method had a significant effect on ratings (p = .0005) with BDD electrodes showing less effect. Conclusions Bleaching by applying BDD electrodes was possible, but was not as effective as the use of commercially available in-office whitening gel. A potential explanation may be seen in different concentrations of reactive oxygen species