Multilateral analysis of increasing collective dose and new ALARA programme

JAPC (The Japan Atomic Power Company) is the only electric power company that operates different types of nuclear reactors in Japan; it operates two BWRs (boiling water reactors), one pressurised water reactor and one gas cooled reactor. JAPC has been conducting various activities aimed at reducing radiation dose received by workers for over 45 y. Recently, the collective dose resulting from periodic maintenance has increased at each plant because of the replacement of large equipment and the unexpected extension of the outage period. In particular, the collective dose at Tokai-2 is one of the highest among Japanese BWR plants((1)), owing to the replacement and strengthening of equipment to meet earthquake-proof requirements. In this study, the authors performed a multilateral analysis of unacceptably a large collective dose and devised a new ALARA programme that includes a 3D dose prediction map and the development of machines to assist workers.     

A Hydrogen Management Method in Residential Distributed Generation Systems with Photovoltaic Cells and Hydrogen‐Storage Type Fuel Cells

Recently, renewable energy has been attracting attention as a result of global warming and the depletion of fossil fuels. Photovoltaic (PV) systems have spread rapidly around the world because they generate electric power quietly and can be installed in many places. The output power generated in a PV system fluctuates with changes in solar irradiance and panel temperature. The reverse flow of surplus power in output spikes may have a negative effect on electric power quality, such as on the frequency and voltage in a power system. A residential distributed generation (DG) system composed of a fuel cell (FC) unit, an electrolyzer (EL) unit, and a PV system has been proposed in order to resolve these problems. In order to operate this system without interruption, the hydrogen storage volume must be managed. This paper proposes a novel hydrogen management method for a residential DG system with PV cells and hydrogen‐storage type FCs. The hydrogen storage volume is maintained at the preset frequency by operating the FC unit and the EL unit. Models of the PV, FC, and EL were constructed for a simulation. In the simulation, we showed that the proposed management method is viable for a residential DG system with PV cells and hydrogen‐storage FCs.     

Water Network in Room-Temperature Ionic Liquid: <Emphasis Type="Italic">N,N</Emphasis>-Diethyl-<Emphasis Type="Italic">N</Emphasis>-Methyl-<Emphasis Type="Italic">N</Emphasis>-2-Methoxyethyl Ammonium Tetrafluoroborate

Crystal structures of room-temperature ionic liquid (RTIL)-H₂O mixtures are determined by the X-ray diffraction method. The RTIL is N,N-diethyl-N-methyl-N-2-methoxyethyl ammonium tetrafluoroborate, [DEME][BF₄]. At 0.9 mol pct H₂O, two kinds of superstructures occur simultaneously without a strain. Also, the volume of the unit cell is very small only at 0.9 mol pct additives. This relates to the composite domain structure, including a twin-related one, as an elastic anomaly. At other water concentrations, such an extraordinary behavior is not observable. By assuming a sublattice having an equivalent lattice constant, a water network at 1 mol pct H₂O is simulated using a Monte Carlo (MC) method. The network develops over the medium range in the simulation box.     

Genotoxicity of nano/microparticles in in vitro micronuclei, in vivo comet and mutation assay systems

Background

Recently, manufactured nano/microparticles such as fullerenes (C₆₀), carbon black (CB) and ceramic fiber are being widely used because of their desirable properties in industrial, medical and cosmetic fields. However, there are few data on these particles in mammalian mutagenesis and carcinogenesis. To examine genotoxic effects by C₆₀, CB and kaolin, an in vitro micronuclei (MN) test was conducted with human lung cancer cell line, A549 cells. In addition, DNA damage and mutations were analyzed by in vivo assay systems using male C57BL/6J or gpt delta transgenic mice which were intratracheally instilled with single or multiple doses of 0.2 mg per animal of particles.

Results

In in vitro genotoxic analysis, increased MN frequencies were observed in A549 cells treated with C₆₀, CB and kaolin in a dose-dependent manner. These three nano/microparticles also induced DNA damage in the lungs of C57BL/6J mice measured by comet assay. Moreover, single or multiple instillations of C₆₀ and kaolin, increased either or both of gpt and Spi^- mutant frequencies in the lungs of gpt delta transgenic mice. Mutation spectra analysis showed transversions were predominant, and more than 60% of the base substitutions occurred at G:C base pairs in the gpt genes. The G:C to C:G transversion was commonly increased by these particle instillations.

Conclusion

Manufactured nano/microparticles, CB, C₆₀ and kaolin, were shown to be genotoxic in in vitro and in vivo assay systems.     

Multicopy suppressors of the sly1 temperature-sensitive mutation in the ER-Golgi vesicular transport in Saccharomyces cerevisiae

Saccharomyces cerevisiae Sly1 protein is a member of the Sec1/Munc18-family proteins, which are essential for vesicular trafficking, but their exact biological roles are yet to be determined. A temperature-sensitive sly1 mutant arrests the vesicular transport from the ER to Golgi compartments at 37 degrees C. We screened for multicopy suppressor genes that restore the colony formation of the sly1(ts) mutant to discover functionally interacting components. The suppressor genes obtained were classified as: (1) those that encode a multifunctional suppressor, SSD1; (2) heat shock proteins, SSB1 and SSB2; (3) cell surface proteins, WSC1, WSC2 and MID2; (4) ER-Golgi transport proteins, USO1 and BET1; and (5) an as-yet-uncharacterized protein, HSD1 (high-copy suppressor of SLY1 defect 1). By epitope tagging of the gene product, we found that Hsd1 protein is an ER-resident membrane protein. Its overproduction induced enlargement of ER-like membrane structures.     

Amino acid sequence, spectral, oxygen-binding, and autoxidation properties of indoleamine dioxygenase-like myoglobin from the gastropod mollusc Turbo cornutus

Myoglobin was isolated from the radular muscle of the archaeogastropod mollusc Turbo cornutus (Turbinidae). This myoglobin is a monomer carrying one protoheme group; the molecular mass was estimated by SDS-PAGE to be about 40 kDa, 2.5 times larger than that of usual myoglobin. The cDNA-derived amino acid sequence of 375 residues was determined, of which 327 residues were identified directly by chemical sequencing of internal peptides. The amino acid sequence of Turbo myoglobin showed no significant homology with any other usual 16-kDa globins, but showed 36% identity with the myoglobin from Sulculus diversicolor (Haliotiidae) and 27% identity with human indoleamine 2,3-dioxygenase, a tryptophan-degrading enzyme containing heme. Thus, the Turbo myoglobin can be counted among the myoglobins which evolved from the same ancestor as that of indoleamine 2,3-dioxygenase. The absorbance ratio of gamma to CT maximum (gamma/CT) of Turbo metmyoglobin was 17.8, indicating that this myoglobin probably possesses a histidine residue near the sixth coordination position of heme iron. The Turbo myoglobin binds oxygen reversibly. Its oxygen equilibrium properties are similar to those of Sulculus myoglobin, giving P50 = 3.5 mm Hg at pH 7.4 and 20 degrees C. The pH dependence of autoxidation of Turbo oxymyoglobin was quite different from that of mammalian myoglobin, suggesting a unique protein folding around the heme cavity of Turbo myoglobin. A kinetic analysis of autoxidation indicates that the amino acid residue with pKa = 5.4 is involved in the reaction. The autoxidation reaction was enhanced markedly at pH 7.6, but not at pH 5.5 and 6.3 in the presence of tryptophan. We suggest that a noncatalytic binding site for tryptophan, in which several dissociation groups with pKa > or = 7.6 are involved, remains in Turbo myoglobin as a relic of molecular evolution.     

Clinicopathological analysis and therapy in hepatitis C virus-associated nephropathy

The authors evaluated, using computer image analysis system, 15 renal biopsy specimens from patients with MCD and 15 from patients with FSGS. As a control group 5 biopsy and 10 autopsy renal specimens were used. These studies revealed, that in MCD glomeruli showed proliferative changes unrecognizable by light microscopy. In FSGS glomeruli without sclerotic changes were larger than in controls and showed glomerular cells proliferation (per unit of glomerular area) similar to MCD. FSGS in comparison with MCD showed larger glomeruli and prominent interstitial fibrosis. These observations appeared to be helpful in distinguishing MCD and recent forms of FSGS. There were no correlations between relative interstitial volume and glomerular changes in MCD as well as in FSGS. The authors concluded, that histomorphometry can't be used instead of morphological examinations of renal biopsy specimens, but it gives objective informations about progression of the illness and may be useful in differential diagnosis of selected cases of MCD and FSGS.     

The structure and organization of the human NPAT gene

Ataxia telangiectasia (AT) is an autosomal recessive gene disorder, and ATM, a housekeeping gene, has been identified as the gene responsible for AT. Recently we found that another housekeeping gene, NPAT, is located upstream of ATM on human chromosome 11. The two housekeeping genes are transcribed in opposite directions and share a 0.5-kb 5' flanking sequence. The structure and organization of NPAT were determined by direct sequencing of cosmid clones carrying the gene and by application of the long and accurate (LA)-PCR method to amplify regions encompassing the exon/intron boundaries and all of the exons. The gene spans at least 44 kb and consists of 18 exons and 17 introns. It has been suggested that AT heterozygotes have an increased risk of developing cancer, especially breast cancer in women. Frequently, loss of heterozygosity at loci on 11q22-q24 has been observed in DNA isolated from tumors of the breast, uterine cervix, and colon, perhaps suggesting the location of a tumor suppressor gene in 11q22-q24. For investigation of the role of NPAT in AT and these tumors with allelic loss of 11q22-q24, appropriate primer sequences and PCR conditions for amplification of all the NPAT exons from genomic DNA were determined. We previously reported that no recombinations are found among Atm, Npat, and Acat1 (acetoacetyl-CoA thiolase) loci as determined by fine genetic linkage mapping of the mouse AT region. The results of the LA-PCR analysis using NPAT- and ACAT-specific primers and human genomic DNA allowed us to map ACAT 12 kb centromeric to NPAT.