Organochlorine contaminants in human adipose tissues from China: mass balance approach for estimating historical Chinese exposure to DDTs

Concentrations of persistent organochlorines (OCs), such as DDTs, hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB), polychlorinated biphenyls (PCBs), and chlordane compounds (CHLs) were determined in 34 human adipose tissues collected from Guizhou Province, southern China, during 2002. DDT was the predominant contaminant among OCs analyzed; concentrations ranged from 420 to 20 000 ng/g on a lipid wt basis (average +/- sd: 5700 +/- 4100 ng/g). Concentrations of DDTs and the ratio of p,p'-DDT/ sigmaDDT in humans in China were significantly higher than those reported for developed countries. DDT levels in humans in Guizhou Province were comparable to those from Shanghai City, implying the presence of significant sources of DDTs in inland and coastal areas in China. Age-dependent accumulation of HCH concentration was found in this study, possibly because of the considerable reduction in average dairy intake (ADI) of HCHs by Chinese during the recent two decades. On the basis of the information of the ADI rates, half-lives, and body burdens of DDTs, the magnitude of historical DDT exposures by Chinese was estimated. This suggested that approximately 80% of DDTs deposited in Chinese adipose tissues was accumulated before the 1990s. The monitoring of OC levels and epidemiological studies are needed in China to understand the status of contamination and the risks to humans.     

TLR ligands of Lactobacillus sakei LK-117 isolated from seed mash for brewing sake are potent inducers of IL-12

Many studies have investigated the immunostimulatory effects of bacteria, such as the anti-allergic effects of lactic acid bacteria (LAB) and LAB-fermented milk. Importantly, these anti-allergic effects have been observed for both viable and nonviable bacteria. However, there are no reported immunological effects of LAB isolated from kimoto, the traditional yeast starter culture used for brewing sake, which also involves spontaneous lactate fermentation. In this study, we determined whether the Leuconostoc mesenteroides and Lactobacillus sakei bacterial strains obtained from kimoto affected the production of interleukin-12 (IL-12), an inducer of the T-helper type-1 immune response. By incubating autoclaved bacteria with J774.1 macrophage-like cells, we found that L. sakei LK-117 induced a sustained increase in IL-12p40 production. The IL-12-inducing ability of LK-117 was unaffected by anti-TLR2 neutralization and was entirely inhibited when the LK-117 cells were treated with RNase. When LK-117 cells were treated with M-1, an N-acetylmuramidase, at varying concentrations and for different periods of time, the ability of the bacteria to induce IL-12 decreased quickly. Although an active fraction could be prepared by chromatography from the soluble products of enzymolysis, the fraction's induction ability was <2% of that of intact organisms, and induction ability disappeared completely upon anti-TLR2 neutralization after treating the active fraction with RNase. These results suggest that single-stranded RNA released from cells that were disrupted by autoclaving might act as a TLR ligand and provide a novel mechanism in which heat-killed LAB could be used to regulate immune activity.     

High fidelity segregation of a YEp vector in [cir0] strains of the yeast Saccharomyces cerevisiae

YEp vectors carrying the GPD promoter and PGK terminator for constitutive expression showed high partition efficiencies specifically in [cir(0)] strains, when DNA fragments were inserted into the cloning site. These plasmids appeared to be more stable than yeast centromeric plasmids, being lost in less than 10(-2) cells after each generation, and more than 90% of the cells carried the plasmids after 20 generations of growth in the absence of selective pressure. The REP3 region was essential together with the GPD promoter and PGK terminator for plasmid equipartitioning in [cir0] strains. The present results suggest that this host-vector system would be useful for astute observation of the phenotype caused by gene overexpression, and for heterogeneous protein production using natural medium, because of efficient partitioning of the plasmid without selective pressure.     

Qubit neural network and its learning efficiency

Neural networks have attracted much interest in the last two decades for their potential to realistically describe brain functions, but so far they have failed to provide models that can be simulated in a reasonable time on computers; rather they have been limited to toy models. Quantum computing is a possible candidate for improving the computational efficiency of neural networks. In this framework of quantum computing, the Qubit neuron model, proposed by Matsui and Nishimura, has shown a high efficiency in solving problems such as data compression. Simulations have shown that the Qubit model solves learning problems with significantly improved efficiency as compared to the classical model. In this paper, we confirm our previous results in further detail and investigate what contributes to the efficiency of our model through 4-bit and 6-bit parity check problems, which are known as basic benchmark tests. Our simulations suggest that the improved performance is due to the use of superposition of neural states and the use of probability interpretation in the observation of the output states of the model.     

Characterization of deep levels in Si‐MOS structure using ICTS measurement

Interface traps and bulk traps induced by heavy metal impurities in Si‐MOS structure were characterized by isothermal capacitance transient spectroscopy (ICTS). In addition, the use of an MOS inversion time is proposed for the detection of a very low density of heavy metal impurities in the ICTS measurements. It is shown that heavy metal impurities enhanced interface trap densities as well as induced bulk traps. The degree of the enhancement varies with the species of heavy metal impurities. Interface traps may be enhanced by the substitutional heavy metal impurities. Moreover, it has been ascertained that a very low level of contamination by heavy metals can be detected by using the MOS inversion time. This has been experimentally shown by the use of a copper impurity. Furthermore, it has been clarified from the change of MOS inversion time that interface traps are also detrimental to the carrier generation lifetime. © 2000 Scripta Technica, Electr Eng Jpn, 130(4): 76–86, 2000     

Plasma-initiated graft polymerization of water-soluble vinyl monomers onto hydrophobic films and its application to metal ion adsorbing films

Plasma-initiated graft polymerization of water-soluble vinyl monomers such as acrylic acid, 2-hydroxyethyl methacrylate and acrylamide was carried out onto polyethylene, polypropylene and poly(ethylene terephthalate) films. It was found that these monomers could be graft polymerized quite easily to 0.5%–670% of the mass of the dry films by exposing the films to a plasma for 90s, with subsequent post-polymerization at room temperature. Thus, polyethylene films capable of adsorbing and desorbing metal ions reversibly could be prepared by grafting the monomers described.     

A Factor Analysis Model for a Mixture of Various Types of Variables

A factor analysis model is proposed for the case of a mixture of various types of discrete and continuous manifest variables. It is indicated that the likelihood of parameters can be described for a mixture of different types of distributions by assuming local independence. For estimation of the parameters of interest, the method of marginal maximum likelihood is used, where scores of latent factors are integrated out from the likelihood. A kind of the EM algorithm is utilized for optimization. As an example, the case of a mixture of normal, binomial and Poisson distributions is provided.

     

Surface morphology control of zirconia thin films prepared using novel photochromic molecules

A new photochromic ZrO₂ precursor solution was prepared using zirconium tetra-n-butoxide, 4-(phenylazo)benzoic acid and ethyleneglycol monomethylether. The density functional theory (DFT) calculation has identified that the structure of the synthesized precursor molecule changed by UV irradiation. Four types of thin films were prepared using the ZrO₂ precursor solution with and without UV irradiation and applying an electric field. It was found that the surface morphology of thin films changed by applying UV irradiation to the precursor solution and an electric field.     

Production of biogenic manganese oxides by repeated-batch cultures of laboratory microcosms

We investigated the production of manganese (Mn) oxides using repeated-batch bioreactors maintained over long periods under laboratory conditions. Freshwater epilithic biofilms were used as the initial inocula. The bioreactors yielded suspended solids that could remove 0.1 mM dissolved Mn(II) within a few days. Chemical titration, X-ray absorption near-edge structure spectroscopy, and X-ray diffraction analysis revealed that the Mn(II) had been converted to poorly crystallized layer-type Mn(IV) oxides, which were similar to known biogenic Mn oxides from pure bacterial cultures. Spherical or rod-shaped Mn microconcretions occurred in the suspended solids; transmission electron microscopy showed that these structures likely resulted from the microbial activity but not represent living cells. Instead, the presence of encapsulated, sheathed, and hyphal budding cells in the suspended solids indicated that a range of Mn-depositing bacteria contributed to the Mn oxide formation. To our knowledge, our data represent the first observation of production of such Mn oxides in a laboratory microcosm wherein a range of Mn-depositing bacteria coexist. The fact that sorption of trace Zn(II) and Ni(II) ions onto the suspended solids co-occurred with the removal of dissolved Mn(II) emphasizes the important role of Mn-oxidizing microorganisms in the fates of trace or contaminant metals in the aquatic environment.     

Mutational Consequences on Replication of M13 Constructs Containing Isomeric Diol Epoxide Adducts in E. coli

Eight isomeric dGuo and eight dAdo adducts resulting from cis and trans opening of each of the four optically active diol epoxides (DEs) derived from benzo[ a ]pyrene (B a P) and benzo[ c ]phenanthrene (B c Ph) were placed in each of two 16-mer DNA sequences to give 32 modified oligonucleotides, which were ligated into M13mp7L2 and allowed to replicate in SOS-induced Escherichia coli . The effects of parent hydrocarbon, adduct stereochemistry, and sequence context on mutagenic response are highly interdependent. B a P DE adducts are generally more mutagenic than the corresponding B c Ph adducts. The mutational frequency is generally larger for cis - relative to trans -opened DE adducts of both dGuo and dAdo. In a ～TA*G～ context, B c Ph DE dAdo adducts (A*) with R configuration at the site of attachment to the adenine base produced very few substitution mutations when compared with adducts having S configuration. This configurational effect is not observed for B a P DE dAdo adducts, nor for B a P or B c Ph dGuo adducts.