819 research outputs found
Antibacterial effect of taurolidine (2%) on established dental plaque biofilm
Preliminary data have suggested that taurolidine may bear promising disinfectant properties for the therapy of bacterial infections. However, at present, the potential antibacterial effect of taurolidine on the supragingival plaque biofilm is unknown. To evaluate the antibacterial effect of taurolidine on the supragingival plaque biofilm using the vital fluorescence technique and to compare it with the effect of NaCl and chlorhexidine (CHX), 18 subjects had to refrain from all mechanical and chemical hygiene measures for 24 h. A voluminous supragingival plaque sample was taken from the buccal surfaces of the lower molars and wiped on an objective slide. The sample was then divided into three equal parts and mounted with one of the three test or control preparations (a) NaCl, (b) taurolidine 2% and (c) CHX 0.2%. After a reaction time of 2 min, the test solutions were sucked of. Subsequently, the plaque biofilm was stained with fluorescence dye and vitality of the plaque flora was evaluated under the fluorescence microscope (VF%). Plaque samples treated with NaCl showed a mean VF of 82.42 ± 6.04%. Taurolidine affected mean VF with 47.57 ± 16.60% significantly (p < 0.001, paired t test). The positive control CHX showed the lowest mean VF values (34.41 ± 14.79%; p < 0.001 compared to NaCl, p = 0.017 compared to taurolidine). Taurolidine possesses a significant antibacterial effect on the supragingival plaque biofilm which was, however, not as pronounced as that of CHX
Manipulating Rydberg atoms close to surfaces at cryogenic temperatures
Helium atoms in Rydberg states have been manipulated coherently with
microwave radiation pulses near a gold surface and near a superconducting NbTiN
surface at a temperature of . The experiments were carried out with
a skimmed supersonic beam of metastable helium atoms excited with laser radiation to
Rydberg levels with principal quantum number between and . The
separation between the cold surface and the center of the collimated beam is
adjustable down to . Short-lived Rydberg levels
were coherently transferred to the long-lived state to avoid
radiative decay of the Rydberg atoms between the photoexcitation region and the
region above the cold surfaces. Further coherent manipulation of the
Rydberg levels with pulsed microwave radiation above the surfaces
enabled measurements of stray electric fields and allowed us to study the
decoherence of the atomic ensemble. Adsorption of residual gas onto the
surfaces and the resulting slow build-up of stray fields was minimized by
controlling the temperature of the surface and monitoring the partial pressures
of HO, N, O and CO in the experimental chamber during the
cool-down. Compensation of the stray electric fields to levels below was achieved over a region of along the
beam-propagation direction which, for the beam
velocity, implies the possibility to preserve the coherence of the atomic
sample for several microseconds above the cold surfaces.Comment: 12 pages, 10 figure
Noise-induced broadening of a quantum-dash laser optical frequency comb
Single-section quantum dash semiconductor lasers have attracted much
attention as an integrated and simple platform for the generation of THz-wide
and flat optical frequency combs in the telecom C-band. In this work, we
present an experimental method allowing to increase the spectral width of the
laser comb by the injection of a broadband optical noise from an external
semiconductor optical amplifier that is spectrally overlapped with the quantum
dash laser comb. The noise injection induces an amplification of the side modes
of the laser comb which acquire a fixed phase relationship with the central
modes of the comb. We demonstrate a broadening of the laser comb by a factor of
two via this technique.Comment: 4 pages, 4 figure
Decoherence and turbulence sources in a long laser
We investigate the turn-on process in a laser cavity where the roundtrip time is several orders of magnitude greater than the active medium timescales. In this long delay limit the electromagnetic field build-up can be mapped experimentally roundtrip after roundtrip. We show how coherence settles down starting from a stochastic initial condition. In the early stages of the turn-on, we show that power drop-outs emerge, persist for several round-trips and seed dark solitons. These latter structures exhibit a chaotic dynamics and emit radiation that can lead to an overall turbulent dynamics depending on the cavity dispersion
Directed Evolution of Microorganisms for Engineered Living Materials
Microorganisms can create engineered materials with exquisite structures and
living functionalities. Although synthetic biology tools to genetically
manipulate microorganisms continue to expand, the bottom-up rational design of
engineered living materials still relies on prior knowledge of
genotype-phenotype links for the function of interest. Here, we utilize a
high-throughput directed evolution platform to enhance the fitness of whole
microorganisms under selection pressure and identify novel genetic pathways to
program the functionalities of engineered living materials. Using
Komagataeibacter sucrofermentans as a model cellulose-producing microorganism,
we show that our droplet-based microfluidic platform enables the directed
evolution of these bacteria towards a small number of cellulose overproducers
from an initial pool of 40'000 random mutants. Sequencing of the evolved
strains reveals an unexpected link between the cellulose-forming ability of the
bacteria and a gene encoding a protease complex responsible for protein
turnover in the cell. The ability to enhance the fitness of microorganisms
towards specific phenotypes and to discover new genotype-phenotype links makes
this high-throughput directed evolution platform a promising tool for the
development of the next generation of engineered living materials
Treatment of MRSA pneumonia: clinical and economic comparison of linezolid vs. vancomycin – a retrospective analysis of medical charts and re-imbursement data of real-life patient populations
Genome-scale metabolic network reconstruction of model animals as a platform for translational research
Genome-scale metabolic models (GEMs) are used extensively for analysis of mechanisms underlying human diseases and metabolic malfunctions. However, the lack of comprehensive and high-quality GEMs for model organisms restricts translational utilization of omics data accumulating from the use of various disease models. Here we present a unified platform of GEMs that covers five major model animals, including Mouse1 (Mus musculus), Rat1 (Rattus norvegicus), Zebrafish1 (Danio rerio), Fruitfly1 (Drosophila melanogaster), and Worm1 (Caenorhabditis elegans). These GEMs represent the most comprehensive coverage of the metabolic network by considering both orthology-based pathways and species-specific reactions. All GEMs can be interactively queried via the accompanying web portal Metabolic Atlas. Specifically, through integrative analysis of Mouse1 with RNA-sequencing data from brain tissues of transgenic mice we identified a coordinated up-regulation of lysosomal GM2 ganglioside and peptide degradation pathways which appears to be a signature metabolic alteration in Alzheimer’s disease (AD) mouse models with a phenotype of amyloid precursor protein overexpression. This metabolic shift was further validated with proteomics data from transgenic mice and cerebrospinal fluid samples from human patients. The elevated lysosomal enzymes thus hold potential to be used as a biomarker for early diagnosis of AD. Taken together, we foresee that this evolving open-source platform will serve as an important resource to facilitate the development of systems medicines and translational biomedical applications
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