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Although poor oral health influences the occurrence of pulmonary infection in elderly people, it is unclear how the degree of oral health is linked to mortality from pulmonary infection. Therefore, we evaluated the relationship between oral health and four-year mortality from pneumonia in an elderly Japanese population. The study population consisted of 697 (277 males, 420 females) of the 1282 individuals who were 80 years old in 1997. Data on oral and systemic health were obtained by means of questionnaires, physical examinations, and laboratory blood tests. One hundred eight of the study persons died between 1998 and 2002. Of these, 22 deaths were due to pneumonia. The adjusted mortality due to pneumonia was 3.9 times higher in persons with 10 or more teeth with a probing depth exceeding 4 mm (periodontal pocket) than in those without periodontal pockets. Therefore, the increase in teeth with periodontal pockets in the elderly may be associated with increased mortality from pneumonia.

Streptococcus mutans has been strongly implicated as the principal etiological agent in dental caries. One of the important virulence properties of these organisms is their ability to form biofilms known as dental plaque on tooth surfaces. Since the roles of sucrose and glucosyltransferases in S. mutans biofilm formation have been well documented, we focused our attention on sucrose-independent factors. We have initially identified several mutants that appear to be defective in biofilm formation on abiotic surfaces by an insertional inactivation mutagenesis strategy applied to S. mutans. A total of 27 biofilm-defective mutants were isolated and analyzed in this study. From these mutants, three genes were identified. One of the mutants was defective in the Bacillus subtilis lytR homologue. Another of the biofilm-defective mutants isolated was a yulF homologue, which encodes a hypothetical protein of B. subtilis whose function in biofilm formation is unknown. The vast majority of the mutants were defective in the comB gene required for competence. We therefore have constructed and examined comACDE null mutants. These mutants were also found to be attenuated in biofilm formation. Biofilm formation by several other regulatory gene mutants were also characterized using an in vitro biofilm-forming assay. These results suggest that competence genes as well as the sgp and dgk genes may play important roles in S. mutans biofilm formation.

The cross sections for single-neutron removal from the very neutron-rich nucleus 31Ne on Pb and C targets have been measured at 230 MeV/nucleon using the RIBF facility at RIKEN. The deduced large Coulomb breakup cross section of 540(70) mb is indicative of a soft E1 excitation. Comparison with direct-breakup model calculations suggests that the valence neutron of 31Ne occupies a low-l orbital (most probably 2p(3/2)) with a small separation energy (S(n) approximately < 0.8 MeV), instead of being predominantly in the 1f(7/2) orbital as expected from the conventional shell ordering. These findings suggest that 31Ne is the heaviest halo system known.

Streptococcus mutans is implicated as a major etiological agent in human dental caries, and one of the important virulence properties of this organism is its ability to form biofilms (dental plaque) on tooth surfaces. We examined the role of autoinducer-2 (AI-2) on S. mutans biofilm formation by constructing a GS-5 luxS-null mutant. Biofilm formation by the luxS mutant in 0.5% sucrose defined medium was found to be markedly attenuated compared to the wild type. Scanning electron microscopy also revealed that biofilms of the luxS mutant formed larger clumps in sucrose medium compared to the parental strain. Therefore, the expression of glucosyltransferase genes was examined and the gtfB and gtfC genes, but not the gtfD gene, in the luxS mutant were upregulated in the mid-log growth phase. Furthermore, we developed a novel two-compartment system to monitor AI-2 production by oral streptococci and periodontopathic bacteria. The biofilm defect of the luxS mutant was complemented by strains of S. gordonii, S. sobrinus, and S. anginosus; however, it was not complemented by S. oralis, S. salivarius, or S. sanguinis. Biofilm formation by the luxS mutant was also complemented by Porphyromonas gingivalis 381 and Actinobacillus actinomycetemcomitans Y4 but not by a P. gingivalis luxS mutant. These results suggest that the regulation of the glucosyltransferase genes required for sucrosedependent biofilm formation is regulated by AI-2. Furthermore, these results provide further confirmation of previous proposals that quorum sensing via AI-2 may play a significant role in oral biofilm formation.Quorum sensing (QS) is a process whereby bacteria communicate with one another by means of the secretion of chemical signal molecules called autoinducers (AIs) (3,4,35,38). In the bioluminescent gram-negative marine bacterium Vibrio harveyi, two distinct AIs, AI-1 (6, 9) and AI-2, regulate light emission (36). LuxS is an enzyme involved in the catabolism of S-adenosylmethionine and converts ribose homocysteine into homocysteine and 4,5-dihydroxy-2,3-pentanedione, the precursor of 46,51). This system has been referred to as an interspecies quorum system and may operate as a universal quorum system for many bacteria possessing the characteristic luxS gene (5). The luxS gene is highly conserved across a diverse range of gram-negative and gram-positive bacterial species, and AI-2 is produced by many of these species. QS enables a population of bacteria collectively to regulate gene expression including expression of virulence factors (21, 39), competence for genetic transformation (1, 28, 37), conjugal DNA transfer (20,52,56), and the production of antibiotics and secondary metabolites (31, 49), as well as biofilm formation (13). However, more recent investigations have also indicated that AI-2 production is regulated at the level of LuxS substrate availability and not at the level of luxS expression. Consequently, AI-2-dependent signaling can also reflect the metabolic state of the cell and not necessarily cell density (7).Biofilms are se...

The BigRIPS in-flight separator, which became operational in March 2007 at the RI Beam Factory (RIBF) at RIKEN Nishina Center, has been used to produce a variety of rare-isotope (RI) beams by using in-flight fission as well as projectile fragmentation. Its major features are large ion-optical acceptances and two-stage structure. Excellent performance in particle identification is also an important feature. Efficient RI-beam production based on the in-flight scheme has been made possible by these features of the BigRIPS separator, allowing us to greatly expand the accessible region of exotic nuclei. An RI-beam delivery line following the BigRIPS separator is designed to work as a forward spectrometer, called ZeroDegree. As a major experimental device at RIBF, the ZeroDegree spectrometer has been used for a variety of reaction studies with RI beams. In this paper, we present an overview of the BigRIPS separator and the ZeroDegree spectrometer, emphasizing the capability and potential of the new-generation RI beam facility, RIBF.

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Tin-based electrocatalysts with different tin species distributions were deposited on the carbon paper substrate by three electrodeposition methods and applied to the selective electroreduction of carbon dioxide to formic acid. Among them, the electrocatalysts prepared using unipolar pulse electrodeposition (UPED) method exhibited the maximum HCOOH faradaic efficiency of 89% at −1.7 V (vs Ag/AgCl) with a current density of 6.0 mA cm −2 and long-term stability in the 0.1 M CO 2saturated KHCO 3 solution. Moreover, the effects of surface oxides species on the performance of tin-based electrocatalysts were systematically investigated via density functional theory (DFT) calculations. The calculation results indicated that both metal tin and tin oxides had excellent catalytic ability for the electrochemical reduction of CO 2 to HCOOH. Specifically, the tetravalent tin (Sn 4+ ) and divalent tin (Sn 2+ ) species can reduce the overpotential and improve the HCOOH selectivity, respectively. In addition, we found that the tin oxides/metal tin interface can suppress the evolution of H 2 , but we observed no obvious effect on the formations of HCOOH and CO. Thus, the actual CO 2 catalytic electroreduction process should be synergistically controlled by the complex surface oxide species on the tin-based electrocatalysts.