Speciation of protein-binding zinc and copper in human blood serum by chelating resin pre-treatment and inductively coupled plasma mass spectrometry

A method for the speciation of zinc and copper binding with proteins in human serum was explored by chelating resin (Chelex-100) pre-treatment and inductively coupled plasma mass spectrometry (ICP-MS). It was shown by a SEC (size-exclusion chromatography)-ICP-MS system that albumin-zinc and albumin-copper (loosely-bound species) could be selectively removed from serum by adsorption on the Chelex-100 resin after the chelating resin pre-treatment, while alpha 2-macroglobulin-zinc and ceruloplasmin-copper (firmly-bound species) remained in the serum. The zinc and copper bound with alpha 2-macroglobulin and ceruloplasmin, respectively, were then determined by ICP-MS after batch treatment of the serum samples with the Chelex-100 resin. In addition, the total concentrations of zinc and copper were also determined by ICP-MS after a 20-fold dilution with 0.1 M HNO3. The albumin-zinc and -copper were estimated as the differences between the concentrations of total and firmly-bound species. The present batch pre-treatment method was applied to the speciation analysis of zinc and copper binding with proteins in sera donated from 25 healthy volunteers as well as from a pregnant woman and a myelodysplastic syndrome patient. The observed concentrations of alpha 2-macroglobulin-zinc and ceruloplasmin-copper were in the ranges 109-202 ng ml-1 (12.4-31.3% of total zinc) and 513-880 ng ml-1 (90.6-99.7% of total copper), respectively. The present method is simple (only addition of the chelating resin and centrifugation is required) and reproducible (average RSD = 2% for alpha 2-macroglobulin-zinc and 1% for ceruloplasmin-copper in intra-assay measurements, and 5% for alpha 2-macroglobulin-zinc and 4% for ceruloplasmin-copper in inter-assay measurements), and there is less risk of contamination during separation.     

Molecular dynamics simulation study on the phase behavior of the Gay-Berne model with a terminal dipole and a flexible tail

To study the effect of the alkyl tail and the terminal dipole on the stability of the liquid crystalline phase of mesogens, we have carried out molecular dynamics simulations for 1CB(4-methyl-4'-cyanobiphenyl) and 5CB(4-n-pentyl-4'-cyanobiphenyl) by using a coarse-grained model. In the coarse-grained model, a 5CB molecule is divided into the rigid part of 1CB moiety, which is represented by an ellipsoid, and the remaining flexible part which is represented by a chain of united atoms. The nonbonded potential between coarse-grained segments is represented by the generalized Gay-Berne (GB) potential and the potential parameters are determined by directly comparing the GB potential with the atomistic potentials averaged over the rotation of the mesogen around its axis. In addition, a dipole moment is placed at one end of the ellipsoid opposite to the flexible tail. The ordered state obtained in the polar 5CB model was assigned as the nematic phase, and the experimental static and dynamical properties were reproduced well by using this coarse-grained model. Both the dipole-dipole interactions and the thermal fluctuation of the flexible tail increase the positional disorder in the director direction, and stabilize the nematic phase. Thus, the nematic phase in the polar 5CB is induced by a cooperative effect of the flexible tail and the terminal dipole. It is noted that a local bilayer structure with head-to-head association is formed in the nematic phase, as experimentally observed by x-ray diffraction measurements.     

Determination of thoron and radon ratio by liquid scintillation spectrometry

Summary A portable liquid scintillation counter was applied for the analysis of alpha-ray energy spectrum to determine the ratio of ²²⁰Rn/²²²Rn in fumarolic gas in the field. A surface-polished vial was developed, by which a Gaussian distribution could be approximated for the alpha-ray energy spectra and the peak areas of the nuclides could be estimated independently, because of the wide FWHM in the liquid scientillation pulse. A fumarolic gas sample was collected in Mt. Kamiyama (Hakoneyama geothermal field in Japan) having low ²²⁰Rn/²²²Rn ratio of 2.20±0.13.     

Adsorption of zinc(II) and copper(II) to Shirasu (pyroclastic flow)

A fundamental study on the adsorption of metal elements on Shirasu, a pyroclastic flow deposit distributed in southern Kyushu, Japan, has been conducted. The adsorption experiment was carried out by a batch method, and by using Zn(II) and Cu(II) under several conditions; the effects of the initial concentration of metal ions, grain size, and pH were investigated. At smaller grain sizes, the amount of Zn(II) and Cu(II) adsorbed increased. At higher pH values, the amount of Zn(II) and Cu(II) adsorbed increased. Plots of the adsorption isotherm indicated that the adsorption of Zn(II) and Cu(II) on Shirasu followed the Langmuir isotherm model, and the Langmuir isotherm constants, W(0) and b, were obtained. W(0) at pH 5.0 was approximately two-times larger than that at pH 3.0. This may reflect an increase in the number of anionic binding sites on the surface of Shirasu with an increase in the pH. The b value for Zn hardly changed with an increase in the pH, and for Cu the value decreased with an increase in the pH. These observations suggest that anionic binding sites have a low stability constant, since the apparent stability constant, b, is obtained as the average of stability constant of all sites on the Shirasu surface.     

Molecular design of tetraazamacrocyclic derivatives bearing a spirobenzopyran and three carboxymethyl moieties and their metal-ion complexing behavior.

Tetraazacyclododecane and tetraazacyclotetradecane derivatives bearing a spirobenzopyran and three carboxymethyl moieties, 1 and 2, and a diethylenetriamine derivative bearing a spirobenzopyran and four carboxymethyl moieties 3 were synthesized. The isomerization behaviors based on the spirobenzopyran moiety of these ligands were studied by UV-visible spectrophotometry in aqueous solutions containing various metal ions at neutral pH. These ligands formed stable 1:1 complexes with lanthanide ions, while the spirobenzopyran moiety was isomerized to its corresponding merocyanine form even under dark conditions. In aqueous solutions containing a lanthanide ion, the absorption spectra of 1 or 2 showed remarkable blue shifts, while absorbances at the maximum absorption wavelengths in the visible region were enhanced; such changes are attributable to the isomerization to the merocyanine form of the spirobenzopyran moiety. These results suggest that the phenolate anion of the merocyanine moiety interacts very strongly with a lanthanide ion bound by the complexing moiety because of the high charge density of lanthanide ions. In contrast, the absorbance of merocyanine form was decreased by the complexation of the macrocyclic ligand with transition metal ions, such as Cu2+ and Zn2+. This result indicates that macrocyclic ligands, 1 and 2, formed complexes with transition metal ions only by the aminocarboxylate moieties, and the phenolate ion of merocyanine moiety was not able to participate in the complexation. This conclusion was also demonstrated by density functional theory calculations.     

Optically active helical structure and magnetic interaction of poly(phenylacetylene)-based polyradicals

We synthesized optically active polyradicals possessing an excess of one-handed helical backbone by helix-sense-selective polymerization (HSSP) of achiral monomers which was promoted by rhodium complex catalyst in the presence of (R)- or (S)-1-phenylethylamine. The monomer, which had two hydroxy groups and a hydrogalvinoxyl unit, gave the corresponding polymer with an optically active helical conformation stabilized by intramolecular hydrogen bonding. The chemical oxidation of the polymer yielded the corresponding optically active helical polyradical with high spin concentration. The static magnetic susceptibility of the chiral polyradical was measured using a SQUID magnetometer. We have found that the stronger antiferromagnetic interaction was observed for the polyradical synthesized by HSSP in comparison with the polyradical via polymerization in the presence of racemic phenylethylamine.     

Muon science in J-PARC

The intensity of proton accelerator has attained to the order to mega-watt, and several MW-class proton accelerators start to operate in the world. J-PARC is a complex of three accelerators, and generates a variety of secondary beams, i.e. muon beam, neutron beam, meson beam and neutrino beam. The muon facility is established in order to provide a pulsed muon beam for various experimental programs. The first muon beam is transported to the experimental area in September 2008. Although the accelerator is still under commissioning, and the beam power doesn’t reach the design value of 1 MW yet, the world strongest pulsed muon beam will be provided shortly. In this paper, we review the muon beam line in J-PARC, and discuss evolved scientific programs.     

Signal Formation of Image-Edge Motion Based on Biological Retinal Networks and Implementation into an Analog Metal-Oxide-Silicon Circuit

A simplified model was proposed for the formation of edge signals and generation of motion signals of a target based on the information processing mechanisms of outer and inner retinas of a vertebrate. Analog metal-oxide-silicon (MOS) integrated circuits were designed based on the model. Simulation program with integrated circuit emphasis (SPICE) simulation results showed the performance of local adaptation over a wide dynamic range in the outer retinal circuit and generation of the velocity signal of a moving edge in the inner retinal circuit. Preliminary experimental results showed local adaptation in a given input range in the outer retinal circuit and the generation of motion pulsed signals in the inner retinal circuit.