Phosphocholine - an agonist of metabotropic but not of ionotropic functions of α9-containing nicotinic acetylcholine receptors.

We demonstrated previously that phosphocholine and phosphocholine-modified macromolecules efficiently inhibit ATP-dependent release of interleukin-1ß from human and murine monocytes by a mechanism involving nicotinic acetylcholine receptors (nAChR). Interleukin-1ß is a potent pro-inflammatory cytokine of innate immunity that plays pivotal roles in host defence. Control of interleukin-1ß release is vital as excessively high systemic levels cause life threatening inflammatory diseases. In spite of its structural similarity to acetylcholine, there are no other reports on interactions of phosphocholine with nAChR. In this study, we demonstrate that phosphocholine inhibits ion-channel function of ATP receptor P2X7 in monocytic cells via nAChR containing α9 and α10 subunits. In stark contrast to choline, phosphocholine does not evoke ion current responses in Xenopus laevis oocytes, which heterologously express functional homomeric nAChR composed of α9 subunits or heteromeric receptors containing α9 and α10 subunits. Preincubation of these oocytes with phosphocholine, however, attenuated choline-induced ion current changes, suggesting that phosphocholine may act as a silent agonist. We conclude that phophocholine activates immuno-modulatory nAChR expressed by monocytes but does not stimulate canonical ionotropic receptor functions.

General and craniofacial development are complex adaptive processes influenced by diversity.

Complex systems are present in such diverse areas as social systems, economies, ecosystems and biology and, therefore, are highly relevant to dental research, education and practice. A Complex Adaptive System in biological development is a dynamic process in which, from interacting components at a lower level, higher level phenomena and structures emerge. Diversity makes substantial contributions to the performance of complex adaptive systems. It enhances the robustness of the process, allowing multiple responses to external stimuli as well as internal changes. From diversity comes variation in outcome and the possibility of major change; outliers in the distribution enhance the tipping points. The development of the dentition is a valuable, accessible model with extensive and reliable databases for investigating the role of complex adaptive systems in craniofacial and general development. The general characteristics of such systems are seen during tooth development: self-organization; bottom-up emergence; multitasking; self-adaptation; variation; tipping points; critical phases; and robustness. Dental findings are compatible with the Random Network Model, the Threshold Model and also with the Scale Free Network Model which has a Power Law distribution. In addition, dental development shows the characteristics of Modularity and Clustering to form Hierarchical Networks. The interactions between the genes (nodes) demonstrate Small World phenomena, Subgraph Motifs and Gene Regulatory Networks. Genetic mechanisms are involved in the creation and evolution of variation during development. The genetic factors interact with epigenetic and environmental factors at the molecular level and form complex networks within the cells. From these interactions emerge the higher level tissues, tooth germs and mineralized teeth. Approaching development in this way allows investigation of why there can be variations in phenotypes from identical genotypes; the phenotype is the outcome of perturbations in the cellular systems and networks, as well as of the genotype. Understanding and applying complexity theory will bring about substantial advances not only in dental research and education but also in the organization and delivery of oral health care.

On the Neimark-Sacker bifurcation in a discrete predator-prey system.

A two-parameter family of discrete models describing a predator-prey interaction is considered, which generalizes a model discussed by Murray, and originally due to Nicholson and Bailey, consisting of two coupled nonlinear difference equations. In contrast to the original case treated by Murray, where the two populations either die out or may display unbounded growth, the general member of this family displays a somewhat wider range of behaviour. In particular, the model has a nontrivial steady state which is stable for a certain range of parameter values, which is explicitly determined, and also undergoes a Neimark-Sacker bifurcation that produces an attracting invariant curve in some areas of the parameter space and a repelling one in others.

Total optical transmission through a small hole in a metal waveguide screen.

We present the theory of total optical transmission through a small hole in metal waveguide screen. Unlike past works on extraordinary optical transmission using arrays, there is only a single hole; yet, the theory predicts total transmission for a perfect electric conductor (not normalized to the hole size) 100% transmission, regardless of how small the hole. This is very surprising considering the usual application of Bethe's theory to waveguide apertures. Comprehensive numerical simulations agree well with the theory and their modal-analysis supports the proposed evanescent-mode mechanism for total transmission. These simulations are extended to show the influence of realistic material response (including loss) at microwave and visible-infrared frequencies. Due to the strong resonant field localization and transmission from only a thin metal screen with a single hole, many promising applications arise for this phenomenon including filtering, sensing, plasma generation, nonlinear optics, spectroscopy, heating, optical trapping, near-field microscopy and cavity quantum electrodynamics.

Minimal-bracketing sets for high-dynamic-range image capture.

This paper considers the problem of high-dynamic-range (HDR) image capture using low-dynamic-range (LDR) cameras. We present three different minimal-bracketing algorithms for computing minimum-sized exposure sets bracketing of HDR scenes. Each algorithm is applicable to a different HDR-imaging scenario depending on the amount of target-scene-irradiance information and real-time image processing available at the time of image acquisition. We prove the optimality of each algorithm with respect to its ability to obtain a theoretically minimum-size bracketing set of exposures. We also provide closed-form expressions for computing minimal-bracketing exposure sets for two common types of HDR-imaging systems, those with geometrically varying and arithmetically varying exposure settings. We experimentally demonstrate the advantages of the proposed methods by capturing and processing multiple HDR scenes using minimal-bracketing and 1-stop bracketing methods. The results show that minimal-bracketing can be used to produce high-quality HDR images, while requiring only one third as many LDR images be acquired compared to 1-stop bracketing. We also perform a detailed SNR analysis that quantifies the tradeoff between signal-to-noise ratio and image-bracketing-set size.

Primidone and essential tremor.

To clarify whether primidone itself, and not only its metabolite phenobarbitone, suppresses essential tremor, the effect of a high single dose of primidone was tested. Of 11 patients, 8 showed a reduction of their tremor by 54%-69% for up to 28 h. The serum concentration of primidone was as expected, whereas those of the metabolites phenyl-ethyl-malonamide and phenobarbitone were very low. The tremor suppression can thus be considered to be an effect of primidone. Three of the 11 patients did not show a reduction of tremor.