Biocompatibility selenium nanoparticles with an intrinsic oxidase-like activity

Selenium nanoparticles (SeNPs) are considered to be the new selenium supplement forms with high biological activity and low toxicity; however, the molecular mechanism by which SeNPs exert the biological function is unclear. Here, we reported that biocompatibility SeNPs possessed intrinsic oxidase-like activity. Using Na₂SeO₃ as a precursor and glutathione as a reductant, biocompatibility SeNPs were synthesized by the wet chemical reduction method in the presence of bovine serum albumin (BSA). The results of structure characterization revealed that synthesized SeNPs were amorphous red elementary selenium with spherical morphology, and ranged in size from 25 to 70 nm size with a narrow distribution (41.4 ± 6.7 nm). The oxidase-like activity of the as-synthesized SeNPs was tested with 3,3′,5,5′-tetramethylbenzidine (TMB) as a substrate. The results indicated that SeNPs could catalyze the oxidization of TMB by dissolved oxygen. These SeNPs showed an optimum catalytic activity at pH 4 and 30 °C, and the oxidase-like activity was higher as the concentration of SeNPs increased and the size of SeNPs decreased. The Michaelis constant (K _m) values and maximal reaction velocity (V _max) of the SeNPs for TMB oxidation were 0.0083 mol/L and 3.042 μmol/L min, respectively.     

Adult neurogenesis and specific replacement of interneuron subtypes in the mouse main olfactory bulb

Background  

New neurons are generated in the adult brain from stem cells found in the subventricular zone (SVZ). These cells proliferate in the SVZ, generating neuroblasts which then migrate to the main olfactory bulb (MOB), ending their migration in the glomerular layer (GLL) and the granule cell layer (GCL) of the MOB. Neuronal populations in these layers undergo turnover throughout life, but whether all neuronal subtypes found in these areas are replaced and when neurons begin to express subtype-specific markers is not known.     

Qualitative and quantitative differences between taste buds of the rat and mouse

Background

Numerous electrophysiological, ultrastructural, and immunocytochemical studies on rodent taste buds have been carried out on rat taste buds. In recent years, however, the mouse has become the species of choice for molecular and other studies on sensory transduction in taste buds. Do rat and mouse taste buds have the same cell types, sensory transduction markers and synaptic proteins? In the present study we have used antisera directed against PLCβ2, α-gustducin, serotonin (5-HT), PGP 9.5 and synaptobrevin-2 to determine the percentages of taste cells expressing these markers in taste buds in both rodent species. We also determined the numbers of taste cells in the taste buds as well as taste bud volume.

Results

There are significant differences (p < 0.05) between mouse and rat taste buds in the percentages of taste cells displaying immunoreactivity for all five markers. Rat taste buds display significantly more immunoreactivity than mice for PLCβ2 (31.8% vs 19.6%), α-gustducin (18% vs 14.6%), and synaptobrevin-2 (31.2% vs 26.3%). Mice, however, have more cells that display immunoreactivity to 5-HT (15.9% vs 13.7%) and PGP 9.5 (14.3% vs 9.4%). Mouse taste buds contain an average of 85.8 taste cells vs 68.4 taste cells in rat taste buds. The average volume of a mouse taste bud (42,000 μm³) is smaller than a rat taste bud (64,200 μm³). The numerical density of taste cells in mouse circumvallate taste buds (2.1 cells/1000 μm³) is significantly higher than that in the rat (1.2 cells/1000 μm³).

Conclusion

These results suggest that rats and mice differ significantly in the percentages of taste cells expressing signaling molecules. We speculate that these observed dissimilarities may reflect differences in their gustatory processing.

     

Fermion family recurrences in the Dyson–Schwinger formalism

We study the multiple solutions of the truncated propagator Dyson–Schwinger equation for a simple fermion theory with Yukawa coupling to a scalar field. Upon increasing the coupling constant g, other parameters being fixed, more than one non-perturbative solution breaking chiral symmetry becomes possible and we find these numerically. These “recurrences” appear as a mechanism to generate different fermion generations as quanta of the same fundamental field in an interacting field theory, without assuming any composite structure. The number of recurrences or flavors is reduced to the question of the value of the Yukawa coupling, and it has no special profound significance in the standard model. The resulting mass function can have one or more nodes and the measurement that potentially detects them can be thought of as a collider-based test of the virtual dispersion relation for the charged lepton member of each family. This requires the three independent measurements of the charged lepton’s energy, three-momentum and off-shellness. We illustrate how this can be achieved for the (more difficult) case of the tau lepton. PACS 12.15.Ff; 11.30.Rd     

Twisted Poincaré Duality for some Quadratic Poisson Algebras

We exhibit a Poisson module restoring a twisted Poincaré duality between Poisson homology and cohomology for the polynomial algebra endowed with Poisson bracket arising from a uniparametrised quantum affine space. This Poisson module is obtained as the semiclassical limit of the dualising bimodule for Hochschild homology of the corresponding quantum affine space. As a corollary we compute the Poisson cohomology of R, and so retrieve a result obtained by direct methods (so completely different from ours) by Monnier. This research of the first author was supported by a Marie Curie Intra-European Fellowship within the 6th European Community Framework Programme. The second author was supported by EPSRC Grant EP/D034167/1.     

The Sixth Painlevé Equation as Similarity Reduction of $${\widehat{\mathfrak{gl}}_3}$$ Generalized Drinfel’d–Sokolov Hierarchy

Scaling symmetry of -type Drinfel’d–Sokolov hierarchy is investigated. Applying similarity reduction to the hierarchy, one can obtain the Schlesinger equation with (n + 1) regular singularities. Especially in the case of n = 3, the hierarchy contains the three-wave resonant system and the similarity reduction gives the generic case of the Painlevé VI equation. We also discuss Weyl group symmetry of the hierarchy.      

Quantitative Time-Resolved Fluorescence Spectrum of the Cortical Sarcoma and the Adjacent Normal Tissue

The difference in time-resolved fluorescence spectrum between the cortical sarcoma and the adjacent normal tissue was studied in both experimental and theoretical ways. The Clinical data were obtained in vivo using a time-resolved fluorescence spectrometer employing a single fiber-optic probe for excitation and detection. Tissue was modeled as s-180 sarcoma tumor surrounded with normal muscle and was mediated by the Palladium-porphyrin photosensitizer (Pd-TCPP). The emitted fluorescence was considered as arising from the tumor tissue or the normal muscle, due to the presence of the photosensitizer. A computational code which could simulating time-resolved fluorescence emission was presented and applied to comparing fluorescence decay of photosensitizer in different stages of tumor growth. In this code the different stages of the tumor was modeled through changing the time τ, the delay of the fluorescence photon emission and z _max, the thickness of the tumor. It was found in the in vivo experiment that the fluorescence from tumor tissue decayed more quickly than from the adjacent normal muscle. For the ten rats in the first experiment day, the mean decay constant of tumor T _s and normal tissue T _n were 554 and 526 μs, respectively. And T _s increased with the tumor growth, from 554 μs in the first day to 634 μs in the eighth day while T _s kept steady. It was believed that the more adequate oxygen supplied by the normal tissue can more effectively quench the fluorescence and in the normal tissue the photosensitizer lifetime is smaller. As a result the simulated time-resolved fluorescence spectrum of normal tissue showed more quickly decay. And the thickness of the tumor can also delay the fluorescence decay. Both the experimental and simulated results indicated that the germination of the tumor would increase the decay constant of the time-resolved fluorescence spectrum. So decay constant of the tumor tissue spectrum should be larger than that of adjacent normal tissue for the reason of hypoxia and overgrouth. This fact could be of use in the tumor diagnoses.     

Calcium Ion-Induced Stabilization and Refolding of Agkisacutacin from <Emphasis Type="Italic">Agkistrodon Acutus</Emphasis> Venom Studied by Fluorescent Spectroscopy

Agkisacutacin isolated from the venom of Agkistrodon acutus is a coagulation factor IX / coagulation factor X-binding protein with marked anticoagulant- and platelet-modulating activities. Ca²⁺ ion-induced stabilization and refolding of Agkisacutacin have been studied by following fluorescent measurements. Ca²⁺ ions not only increase the structural stability of agkisacutacin against GdnHCl denaturation, but also induce its refolding. The GdnHCl-induced unfolding of the apo-agkisacutacin and the purified agkisacutacin is a single-step process with no detectable intermediate state. Ca²⁺ ions play an important role in the stabilization of the structure of agkisacutacin. Ca²⁺-stabilized agkisacutacin exhibits higher resistance to GdnHCl denaturation than the apo-agkisacutacin. It is possible to induce refolding of the unfolded apo-agkisacutacin merely by adding 1 mM Ca²⁺ ions without changing the concentration of the denaturant. The kinetic result of Ca²⁺-induced refolding provides evidences for that agkisacutacin consists of at least two refolding phases and the first phase of Ca²⁺-induced refolding should involve the formation of the compact Ca²⁺-binding site regions, and subsequently, the protein undergoes further conformational rearrangements to form the native structure.     

Flexible carbon nanostructures with electrospun nickel oxide as a lithium-ion battery anode

Carbon nanostructures (CNS) with high electrical conductivity and unique branched structure of carbon nanotubes combined with NiO nanofibers (NFs) were used as anode for lithium-ion batteries. CNS works as a framework substrate for the anodic conversion reaction of nickel oxide (NiO). Electrochemical performance and behavior of CNS/NiO anodes is compared with the conventional carbon (C)/NiO anodes. CNS/NiO NF-based anode retains high specific capacity under different current densities compared to C/NiO anode. Moreover, specific capacity as high as 450 mAh/g for CNS/NiO NF anode is observed compared to only 90 mAh/g for C/NiO NFs using a current density of 500 mA/g after 500 cycles. This improved performance is attributed to the highly conductive network of CNS leading to efficient charge transfer. The high porosity, electrical conductivity as well as the branched and networked nature of CNS reveal to be of critical importance to allow the electrochemical conversion reactions.     

Allocating operating funding in the public sector and the newsvendor problem

Public sector managers, particularly those at the highest level of government, tend to view lapsed (or unused) funds at the end of a fiscal year as a consequence of poor management and/or inadequate financial controls. The aim of this paper is to challenge this view. We show that the planning environment in the public sector is in essence the classical Newsvendor Problem. This simple model argues that lapsed funds are a direct consequence of a manager doing his job properly; that is, lapsed funds occur from time to time when a manager is maximizing value for the organization. An extension of the model shows that allowing low-value year-end spending has an undesirable effect on the value of spending during the year and this suggests a role for a strong audit function for year-end spending.