Enzymatic degradation of glucosaminoglucan and cellulase resistance of cellulose nanofiber coated with glucosaminoglucan.

AIMS: Enzymatic degradation of ß-1,4-linked glucose and glucosamine (glucosaminoglucan, GG), which is prepared from Thiothrix nivea and can act as a cellulose-aminating agent with a strong affinity to cellulose, was attempted. METHODS AND RESULTS: A chitosanase-secreting fungal strain was isolated as a GG-degrading microbe. GG was found to be degraded by not only chitosanases but also cellulases. Based on nuclear magnetic resonance spectroscopy, both enzymes were found to produce GlcN-Glc from GG. The cellulases also produced GlcN-Glc-GlcN-Glc as an additional final digest. Furthermore, aminated (GG-coated) cellulose nanofibers exhibited cellulase resistance. The flexibility of GG adsorbed onto a cellulose crystal was almost identical to that of cellulose, as estimated via the molecular dynamics calculations. CONCLUSIONS: The chitosanase and cellulase hydrolyzed the ß-1,4-linkage from Glc to GlcN and were expected to recognize the tetramer and hexamer units of GG depending on their final products. The cellulose nanofibers acquired cellulase resistance via amination with GG, probably because of the lower activity of cellulase to GG than cellulose.

Having few remaining teeth is associated with a low nutrient intake and low serum albumin levels in middle-aged and older Japanese individuals: findings from the NIPPON DATA2010.

BACKGROUND: Oral health is thought to be associated with diet quality, and socioeconomic status (SES) affects both oral health and diet. The aim of this study was to investigate the association between the number of teeth and dietary intake as well as nutritional biomarker, considering the subjects' SES. METHODS: We conducted a cross-sectional analysis of data from 2049 individuals aged ≥ 50 years from the National Integrated Project for Prospective Observation of Non-communicable Disease and its Trends in the Aged 2010. The number of remaining teeth was categorized into age-specific quartiles (Q1 to Q4). We assessed the adjusted means and 95% confidence intervals for dietary variables by the number of teeth using analysis of covariance. Stratified analyses by SES were also conducted. RESULTS: The intake of grain products was 31 g higher, and those of vegetables and meat were 30 g and 8 g lower, respectively, in Q1 (fewer teeth) than in Q4 (more teeth). Carbohydrate intake was higher whereas protein, minerals (potassium, magnesium, and zinc), vitamins (vitamins A, E, B1, B6, ß-carotene, and folic acid), and dietary fiber intakes were lower among individuals with fewer teeth. Adjusted mean serum albumin levels were low in Q1. The associations between the number of teeth and dietary intake were more evident in individuals with a low SES. CONCLUSIONS: Having few remaining teeth was associated with a low nutrient intake and low serum albumin levels in middle-aged and older Japanese adults, and these associations were more evident in individuals with low SES.

Classification of fungal glucuronoyl esterases (FGEs) and characterization of two new FGEs from Ceriporiopsis subvermispora and Pleurotus eryngii.

Fungal glucuronoyl esterases (FGEs) catalyze cleavage of the ester bond connecting a lignin alcohol to the xylan-bound 4-O-methyl-D-glucuronic acid of glucuronoxylans. Thus, FGEs are capable of degrading lignin-carbohydrate complexes and have potential for biotechnological applications toward woody biomass utilization. Therefore, identification and characterization of new FGEs are of critical importance. Firstly, in this study, we built a phylogenetic tree from almost 400 putative FGEs obtained on BLAST analysis and defined six main clades. In the phylogenetic tree, all the putative FGEs of ascomycetes cluster in clades I to IV, and most of the putative FGEs of basidiomycetes (B-FGEs) cluster in clades V to VI. Interestingly, several B-FGEs were found to cluster in clade II; most FGEs of clade II were found to have higher theoretical isoelectric points than those in the other five clades. To gain an insight into the putative FGEs in the clades that have not been characterized yet, we chose the FGEs of Ceriporiopsis subvermispora (CsGE) and Pleurotus eryngii (PeGE), which belong to clades V and II, respectively. The catalytic domains of both CsGE and PeGE were successfully expressed using Pichia pastoris, and then purified. Benzyl glucuronic acid was used as a substrate to confirm the activities of the CsGE and PeGE, and the hydrolyzed product, glucuronic acid, was quantified spectrophotometrically. Both CsGE and PeGE clearly exhibited the esterase activity. Additionally, we demonstrated that PeGE exhibits high tolerance toward several denaturing agents, which may make it a potentially more applicable enzyme.

Effects of ozone nano-bubble water on periodontopathic bacteria and oral cells - in vitro studies.

The aims of the present study were to evaluate the bactericidal activity of a new antiseptic agent, ozone nano-bubble water (NBW3), against periodontopathogenic bacteria and to assess the cytotoxicity of NBW3 against human oral cells. The bactericidal activities of NBW3 against representative periodontopathogenic bacteria, Porphyromonas gingivalis (P. gingivalis) and Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) were evaluated using in vitro time-kill assays. The cytotoxicity of NBW3 was evaluated using three-dimensional human buccal and gingival tissue models. The numbers of colony forming units (CFUs)/mL of P. gingivalis and A. actinomycetemcomitans exposed to NBW3 dropped to below the lower limit of detection (<10 CFUs mL-1) after only 0.5 min of exposure. There were only minor decreases in the viability of oral tissue cells after 24 h of exposure to NBW3. These results suggest that NBW3 possesses potent bactericidal activity against representative periodontopathogenic bacteria and is not cytotoxic to cells of human oral tissues. The use of NBW3 as an adjunct to periodontal therapy would be promising.

Enhancing Bioethanol Production from Rice Straw through Environmentally Friendly Delignification Using Versatile Peroxidase.

Rice straw (RS), an agricultural residue rich in carbohydrates, has substantial potential for bioethanol production. However, the presence of lignin impedes access to these carbohydrates, hindering efficient carbohydrate-to-bioethanol conversion. Here, we expressed versatile peroxidase (VP), a lignin-degrading enzyme, in Pichia pastoris and used it to delignify RS at 30 °C using a membrane bioreactor that continuously discarded the degraded lignin. Klason lignin analysis revealed that VP-treatment led to 35% delignification of RS. We then investigated the delignified RS by SEC, FTIR, and SEM. The results revealed the changes of RS caused by VP-mediated delignification. Additionally, we compared the saccharification and fermentation yields between RSs treated with and without VP, VP-RS, and Ctrl-RS, respectively. This examination unveiled an improvement in glucose and bioethanol production, VP-RS exhibiting up to 1.5-fold and 1.4-fold production, respectively. These findings underscore the potential of VP for delignifying RS and enhancing bioethanol production through an eco-friendly approach.

[Relationship between oral health status and life behavior in junior and senior high school students in Japan].

A survey of dental diseases carried out by the Ministry of Health, Labour and Welfare in 2003 revealed that more than 40% of people aged between 5 and 25 suffer from periodontal diseases and the average number of DMFT has been decreasing. The lifestyle of junior and senior high school students in particular has changed drastically. This study investigated the relationship between dietary habits and oral diseases in junior and senior high school students in Tokyo. Survey responses were received from 813 of 848 students. There was a significant correlation between the presence of untreated teeth and student's dietary habits, or the presence of periodontal diseases. These results suggest that dental hygienists need to consider providing advice on appropriate eating habits during dental hygiene instruction to students.

The neutralizing effect of mouth rinsing with alkaline electrolyzed water on different regions of the oral cavity acidified by acidic beverages.

PURPOSE: Acids contained in foods and drinks are involved in the initiation and progression of dental erosion which causes tooth wear. The authors evaluated the neutralizing activity of alkaline electrolyzed water (AEW) in vitro and in vivo. METHODS: The neutralizing ability of AEW against eight beverages was investigated in vitro. Furthermore, in an in vivo study, the effect of mouth rinsing with AEW on the pH of the oral cavity acidified with acidic beverages was examined. Following mouth rinsing, the oral pH was measured using a pH meter with a micro pH-sensor at the cervical surface of the mandibular teeth and the surface of soft tissues. RESULTS: Regarding the neutralizing ability, the higher the pH of the AEW, the lower the volume required for neutralization of the tooth surface. Changes in the pH by mouth rinsing with AEW and purified tap water (PTW) were analyzed. The degree of increase of pH with AEW was greater than with PTW at almost all sites. CONCLUSION: These results suggest that AEW has the potential to prevent the initiation and progression of dental erosion. Mouth rinsing with AEW could be a simple and effective way to prevent the initiation and progression of dental erosion and dental caries.

Dental Hygiene Learning Outcomes Obtained Through Computer-Assisted Simulation Modules.

Purpose: Education reflecting current knowledge is required for competent health care providers but the number of educators and/or lecture/clinical contact hours are often limited. The purpose of this study was to evaluate the learning outcomes and practicality of interactive simulation modules developed for a computerized learning system in dental hygiene education.Methods: Twenty-nine Japanese fourth-year dental hygiene undergraduates were given access to five interactive modules, delivered via a learning management system (LMS), for one month. The modules provided virtual clinical settings to take learners through decision-making processes for explaining procedures and treatments, and making appointments in English. Pre- and post-tests and a questionnaire were used to evaluate the knowledge gained and to receive learner's feedback. Participants were classified into two groups (study group and non-study group), based on their use/non-use of modules made available during the five-week period for statistical analysis.Results: Post-test scores were significantly higher in the study group (n = 22) than in the non-study group (n = 6), (p = 0.024). Post-test scores were also significantly higher than the pre-test scores in the study group (p = 0.001). No significant differences in the post- versus pre-test scores were found in the non-study group. The questionnaire response rate of 100% (n = 29) indicated that participants considered the interactive modules, including the system operation, as convenient and beneficial.Conclusion: Modules made available via a LMS for self-study were beneficial for Japanese undergraduate dental hygiene students in the acquisition of knowledge and skills for clinical decision-making in English.

NMR Analysis on Molecular Interaction of Lignin with Amino Acid Residues of Carbohydrate-Binding Module from Trichoderma reesei Cel7A.

Lignocellulosic biomass is anticipated to serve as a platform for green chemicals and fuels. Nonproductive binding of lignin to cellulolytic enzymes should be avoided for conversion of lignocellulose through enzymatic saccharification. Although carbohydrate-binding modules (CBMs) of cellulolytic enzymes strongly bind to lignin, the adsorption mechanism at molecular level is still unclear. Here, we report NMR-based analyses of binding sites on CBM1 of cellobiohydrolase I (Cel7A) from a hyper-cellulase-producing fungus, Trichoderma reesei, with cellohexaose and lignins from Japanese cedar (C-MWL) and Eucalyptus globulus (E-MWL). A method was established to obtain properly folded TrCBM1. Only TrCBM1 that was expressed in freshly transformed E. coli had intact conformation. Chemical shift perturbation analyses revealed that TrCBM1 adsorbed cellohexaose in highly specific manner via two subsites, flat plane surface and cleft, which were located on the opposite side of the protein surface. Importantly, MWLs were adsorbed at multiple binding sites, including the subsites, having higher affinity than cellohexaose. G6 and Q7 were involved in lignin binding on the flat plane surface of TrCBM1, while cellohexaose preferentially interacted with N29 and Q34. TrCBM1 used much larger surface area to bind with C-MWL than E-MWL, indicating the mechanisms of adsorption toward hardwood and softwood lignins are different.

Identification of key residues for activities of atypical glutathione S-transferase of Ceriporiopsis subvermispora, a selective degrader of lignin in woody biomass, by crystallography and functional mutagenesis.

Ceriporiopsis subvermispora (C. subvermispora) is a selective degrader of lignin in the woody biomass. Glutathione S-transferases (GSTs) are multifunctional enzymes that play important roles in cellular detoxification and metabolism. The crystal structures of a GST of C. subvermispora, CsGST83044, in GSH-free and -bound forms were solved at 1.95 and 2.19 Šresolution, respectively. The structure of the GSH-bound form revealed that CsGST83044 can be categorized as an atypical-type of GST. In the GSH-bound form of CsGST83044, Asn22, Asn24, and Tyr46 are located closest to the sulfur atom and form hydrogen bonds with the thiol group. The functional mutagenesis indicated that they are critical for the enzymatic activities of CsGST83044. The critical residues of an atypical-type GST belonging to the GSTFuA class were revealed for the first time. A previous study indicated that CsGST83044 and another GST, CsGST63524, differ in substrate preference; CsGST83044 prefers smaller substrates than CsGST63524 for its esterase activity. The GSH-bound pocket of CsGST83044 turns out to be small, which may explain the preference for smaller substrates. Protein engineering of GSTs of C. subvermispora in the light of the obtained insight may pave a path in the future for utilization of the woody biomass.

An Inter- and Intraprofessional Education Program in Which Dental Hygiene Students Instruct Medical and Dental Students.

The aim of this study was to develop, implement, and evaluate an inter- and intraprofessional education program with a peer support joint practice in which dental hygiene students teach medical and dental students about oral health care for older people requiring long-term care. In 2015 at Tokyo Medical and Dental University, 22 dental hygiene students in their third year at the School of Oral Health Care Sciences (OH3), 110 students in their third year at the School of Medicine (M3), and 52 students in their third year at the School of Dentistry (D3) participated in this program. The OH3 students practiced with a whole-body-type simulator to learn oral health care for older people and then taught the methods to the M3 and D3 students according to their self-designed teaching plan. All M3 and D3 students experienced being both practitioner and patient. The number of respondents and response rates on the questionnaires after the training were 22 (100%), 102 (92.7%), and 52 (100%) for the OH3, M3, and D3 students, respectively. Self-assessment by the OH3 students indicated that they could supervise other students sufficiently (77-86%), and 91% of them found the preclinical practice with the simulator efficient for the peer support joint practice. Almost all the M3 and D3 students reported that they gained understanding of the methods (99%), significance (100%), and important points of oral health care for older people (97%) in addition to the jobs and roles of dental hygienists (93%) because of this program. The M3 students understood the methods and significance of oral health care more deeply than did the D3 students (p<0.05). This study found that an interprofessional program with a peer support joint practice to cultivate practical clinical ability aided in increasing understanding and cooperation between medicine and dentistry.

[Career history and perceptions of dental hygiene education programs--questionnaire mail-in survey of alumni of the School of Dental Hygiene in Tokyo Medical and Dental University].

This study was conducted to investigate the career history and perceptions about dental hygiene education programs among the alumni (1952-1999 graduates) of the School of Dental Hygiene in Tokyo Medical and Dental University. A questionnaire containing demographic, practice characteristics and views on the programs was mailed to 997 alumni in 1999, and 576 alumni (57.8%) responded. Three hundred and forty-one respondents worked as dental hygienists. The majority who responded were in clinical practice. One hundred and thirty-one of the respondents worked in private clinics, 76 in public health centers, and 72 in clinics in companies. The rate of them who worked in public health centers was much higher than the national average cited in the Statistical Report on Public Health Administration and Services. Two hundred and ninety-one respondents reported inadequate programs. The rate of them who reported inadequate programs was significantly higher in alumni who were working than in alumni who were not. The items cited as insufficiently taught at the school were clinical practice, instrumentation, foreign language, psychology, counseling, and nursing related subjects. Thus, many alumni suggested the need for better programs and continuing education. From these results, it was suggested that dental hygienists need to change their education programs in order to meet the present and future needs of more diversified society. This view was particularly prevalent among alumni who were working. The result showed that dental hygiene educators and dental hygienists urgently need to reconsider the professionalism of their field.

[The relationship among eating habits, lifestyles, and oral health status of students].

A questionnaire survey and oral health examination were conducted in 2000. The subjects were students of dental and dental hygiene schools at Tokyo Medical and Dental University. Subjects totaled 101 (48 males, 53 females), and the average age was 22.0 +/- 3.3. The relationship among eating habits, lifestyles, and oral health status of the students was analyzed. The following results were obtained. 1. Almost half of the students did not eat one of the three main meals; that is, breakfast, lunch, or supper. Most of them skipped breakfast. 2. The students who ate rice (traditional Japanese-style food) for breakfast had less DMFT compared with those who ate other foods, such as bread or noodles, or who did not eat breakfast. 3. The amount of stimulated saliva of the students who ate rice for breakfast was greater than that of others. 4. The oral health behavior and nutrition balance of the students who ate rice for breakfast was better than that of others. 5. The students' eating habits were related to their living styles, such as living alone or with the family. From these results, it was suggested that educational emphasis on nutrition balance and eating habits is needed for dental students and dental hygiene students, because in the future they must advise patients on good oral health and general health through good eating habits, as dental professionals.

A high-fiber, low-fat diet improves periodontal disease markers in high-risk subjects: a pilot study.

Periodontal disease is related to aging, smoking habits, diabetes mellitus, and systemic inflammation. However, there remains limited evidence about causality from intervention studies. An effective diet for prevention of periodontal disease has not been well established. The current study was an intervention study examining the effects of a high-fiber, low-fat diet on periodontal disease markers in high-risk subjects. Forty-seven volunteers were interviewed for recruitment into the study. Twenty-one volunteers with a body mass index of at least 25.0 kg/m(2) or with impaired glucose tolerance were enrolled in the study. After a 2- to 3-week run-in period, subjects were provided with a test meal consisting of high fiber and low fat (30 kcal/kg of ideal body weight) 3 times a day for 8 weeks and followed by a regular diet for 24 weeks. Four hundred twenty-five teeth from 17 subjects were analyzed. Periodontal disease markers assessed as probing depth (2.28 vs 2.21 vs 2.13 mm; P < .0001), clinical attachment loss (6.11 vs 6.06 vs 5.98 mm; P < .0001), and bleeding on probing (16.2 vs 13.2 vs 14.6 %; P = .005) showed significant reductions after the test-meal period, and these improvements persisted until the follow-up period. Body weight (P < .0001), HbA1c (P < .0001), and high-sensitivity C-reactive protein (P = .038) levels showed improvement after the test-meal period; they returned to baseline levels after the follow-up period. In conclusion, treatment with a high-fiber, low-fat diet for 8 weeks effectively improved periodontal disease markers as well as metabolic profiles, at least in part, by effects other than the reduction of total energy intake.

Development and evaluation of a new dental model at Tokyo Medical and Dental University for the practice of periodontal pocket probing.

Dental and dental hygiene students must acquire the skill of measuring periodontal pockets and learn to identify the bottom of a pocket, especially of deep periodontal pockets. A new dental model that would enable students to practice measuring deep periodontal pockets was developed at the Tokyo Medical and Dental University. The purpose of this study was to evaluate the feasibility and effectiveness of this model. Twenty dental hygiene students in their third year at the school and twenty-four instructors or dental hygienists of the University Hospital measured periodontal pockets on the newly designed dental model. Feasibility and effectiveness of the model were evaluated based on periodontal probing by the students and instructors, as well as results of a questionnaire. The results demonstrated an intraexaminer agreement (within ±1 mm) averaging 91 percent. The mean percentages of correct answers of the students and instructors were 82 percent and 80 percent, respectively. More than 90 percent of the instructors and students reported that the new model would be suitable for pocket probing training. In the questionnaire, they responded that this practice using the new model would contribute to students' future and that they wanted to try other dental models with various probing depths. The new dental model designed for periodontal pocket probing training was reported to be feasible and effective for student practice.

Presence of alternating glucosaminoglucan in the sheath of Thiothrix nivea.

A sheath-forming sulfa oxidizer, Thiothrix nivea, was mixotrophically cultured in a medium supplemented with acetic acid and sodium disulfide. Its sheath, a microtube-like extracellular supermolecule, was prepared by selectively removing the cells with lysozyme, sodium dodecyl sulfate, and sodium hydroxide. The sheath was not visibly affected by hydrazine treatment, suggesting that it is not a proteinous supermolecule. From the acid hydrolysate of the sheath, glucose and glucosamine were detected in an approximate molar ratio of 1:1. Three other saccharic compounds were detected and recovered by HPLC as fluorescent derivatives prepared by reaction with 4-aminobenzoic acid ethyl ester. Nuclear magnetic resonance (NMR) analysis suggested that one of the derivatives was derived from an unidentified deoxypentose. NMR analysis for the other 2 derivatives showed that they were derived from ß-1,4-linked disaccharides and tetrasaccharides, which were composed of glucose and glucosamine. The sheath was readily broken down by weak HCl treatment, releasing an unidentified deoxypentose and polymer. Chemical analysis showed the presence of ß-1,4-linked D-Glcp and D-GlcNp in the polymer. NMR analysis revealed that the polymer had a repeating unit of →4)-D-Glcp-(ß1→4)-D-GlcNp-(ß1→. The solid-state 1D-(13)C NMR spectrum of the polymer in N-acetylated form supported this result. The molecular weight of the polymer was estimated to be 8.2×10(4) by size exclusion chromatography. Based on these results, the sheath of T. nivea is hypothesized to be assembled from alternately ß-1,4-linked glucosaminoglucan grafted with unidentified deoxypentose.