Dynamics of nitric oxide controlled by protein complex in bacterial system.

Nitric oxide (NO) plays diverse and significant roles in biological processes despite its cytotoxicity, raising the question of how biological systems control the action of NO to minimize its cytotoxicity in cells. As a great example of such a system, we found a possibility that NO-generating nitrite reductase (NiR) forms a complex with NO-decomposing membrane-integrated NO reductase (NOR) to efficiently capture NO immediately after its production by NiR in anaerobic nitrate respiration called denitrification. The 3.2-Å resolution structure of the complex of one NiR functional homodimer and two NOR molecules provides an idea of how these enzymes interact in cells, while the structure may not reflect the one in cells due to the membrane topology. Subsequent all-atom molecular dynamics (MD) simulations of the enzyme complex model in a membrane and structure-guided mutagenesis suggested that a few interenzyme salt bridges and coulombic interactions of NiR with the membrane could stabilize the complex of one NiR homodimer and one NOR molecule and contribute to rapid NO decomposition in cells. The MD trajectories of the NO diffusion in the NiR:NOR complex with the membrane showed that, as a plausible NO transfer mechanism, NO released from NiR rapidly migrates into the membrane, then binds to NOR. These results help us understand the mechanism of the cellular control of the action of cytotoxic NO.

The relationship between subjective oral frailty and adverse health outcomes or medical and dental expenditures in the latter-stage older adult: A 6-year longitudinal study.

OBJECTIVES: The study aimed to investigate the relationship between subjective oral frailty and adverse health outcomes or medical and dental expenditures in the latter-stage older adult through a 6-year longitudinal study. METHODS: The participants enrolled in the cross-sectional study were 3564 Tokushima City residents aged 75, 80, 85, and 90 years old who received oral health examinations and who responded to a questionnaire on oral conditions and health behavior at baseline. The data for the occurrence of disability or mortality, and the monthly medical expenditures, dental expenditures, and total medical expenditure of each participant were obtained from the National Health Insurance Database. RESULTS: The total medical expenditure showed significant differences in participants who had difficulties in eating tough foods, difficulties in swallowing tea or soup, and dry mouth when compared to that of healthy participants, in addition to the current medical treatment against the general disease. The 6-year longitudinal study revealed that participants with subjective oral frailty symptoms, including difficulties in eating tough foods and difficulties in swallowing tea or soup at baseline, had significantly higher medical, dental, and total expenditures among 538 participants without certified nursing care. In addition, those with subjective oral frailty or with less than 19 teeth present were shown to have a higher possibility for the occurrence of disability or mortality by the cox proportional hazard analysis. Furthermore, it was found that medical and total expenditures in older adults with adverse health outcomes were higher than that of healthy participants. CONCLUSION: These results suggest that subjective oral frailty in the latter-stage older adult is related to subsequent adverse health outcomes and an increase in medical and dental expenditures.

Sequence analysis of two ScFv genes of MAbs against Streptococcus mutans glucosyltransferase.

Streptococcus mutans glucosyltransferases (GTFs) are considered to be the principal etiological agents of dental caries. Water-insoluble glucans (WIG) synthesized by those GTFs mediate sucrose-enhanced colonization for the bacterium on tooth surfaces and form dental plaque. GTFs have two functional domains, that is, an N-terminal catalytic sucrose-binding domain involved in sucrose hydrolysis and a C-terminal glucan-binding domain involved in the binding of the synthesized glucan polymer. Two hybridomas, each producing a monoclonal antibody (MAb) that inhibits the WIG synthesis by WIG synthesized GTF (GTF-I), were constructed. Those MAbs, P126 and P136, were shown to be able to recognize the different epitope domains in GTF; P126 recognized the N-terminal region, whereas P136 recognized the C-terminal region. We previously constructed two single chain fragments of immunoglobulin variable regions (ScFvs), which are capable of inhibiting GTF activity, from mice hybridomas producing P126 and P136. In the present study, we analyzed the nucleotide sequences of molecularly cloned ScFv genes (named ScFv/P126 and ScFv/P136), compared them in three complementarity- determining regions (CDRs), and also located their gene loci originate. Our results showed no particular relationship between the two ScFvs, and suggested the use of a certain type of VH or VL gene segment as well as possible evidence of the ability of these two MAbs to recognize different epitopes of GTF proteins.