Equilibrium dialysis and carborydrate-binding studies on the 2-acetamido-2-deoxy--glucopyranosyl-binding lectin from bandeiraea simplicifolia seeds

The carbohydrate-binding specificity of Bandeiraea simplicifolia lectin II (BS II lectin) has been studied by quantitative precipitin and hapten-inhibition analysis. The BS II lectin precipitated biopolymers having nonreducing 2-acetamido-2-deoxy--glucopyranosyl residues, such as antigen A. Dextran B-1355-S and rabbit-liver glycogen also afforded precipitin curves with high concentrations of the BS II lectin. Phenyl 2-acetamido-2-deoxy-[alpha]--glucopyranoside and p-nitrophenyl 2-acetamido-2-deoxy-[alpha]--glucopyranoside, the best inhibitors of the BS II lectin-p-azophenyl 2-acetamido-2-deoxy-[beta]--glucopyranoside-bovine serum albumin conjugate precipitin-system, were 4 times as active as 2-acetamido-2-deoxy--glucopyranose. Of the free monosaccharides tested, 2-acetamido-2-deoxy--glucopyranose was the most potent inhibitor, being over 100 times better than -fructose and 400 times better than -glucose. Comparison of the inhibiting capacity of methyl or p-nitrophenyl 2-acetamido-2-deoxy-[alpha]--glucopyranoside with their corresponding [beta] anomers showed that the [alpha] anomer was bound 6 to 8 times more avidly than the [beta] anomer. Replacement of the C-3, C-4, or C-6 hydroxyl group of -glucose by a methoxyl group or a fluorine atom abolished the capacity of the resulting sugar to bind the BS II lectin, but substitution of the C-2 hydroxyl group of -glucose, by either a methoxyl group or a fluorine group, had no appreciable effect on binding to the lectin. N,N'-Diacetylchitobiose was as active as N,N',N"-triacetylchitotriose, and they were both twice as potent as disaccharides having a nonreducing 2-acetamido-2-deoxy-[beta]--glucopyranosyl residue. Disaccharides having [beta]--(1 --> 6) glycosidic bonds were very poor inhibitors. Equilibrium-dialysis experiments with p-nitrophenyl 2-acetamido-2-deoxy-[alpha]--glucopyranoside as binding ligand indicated that the BS II lectin possesses approximately one carbohydrate-binding siteper subunit for the tetrameric protein (Mr 113,000), with association constants of 1.3 x 105 M-1 at 4[deg], and 0.4 x 105 M-1 at 37[deg].Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22639/1/0000190.pd

Equilibrium dialysis and carbohydrate-binding studies on the 2-acetamido-2-deoxy--glucopyranosyl-binding lectin from Bandeiraea simplicifolia seeds

The carbohydrate-binding specificity of Bandeiraea simplicifolia lectin II (BS II lectin) has been studied by quantitative precipitin and hapten-inhibition analysis. The BS II lectin precipitated biopolymers having nonreducing 2-acetamido-2-deoxy--glucopyranosyl residues, such as antigen A. Dextran B-1355-S and rabbit-liver glycogen also afforded precipitin curves with high concentrations of the BS II lectin. Phenyl 2-acetamido-2-deoxy-[alpha]--glucopyranoside and p-nitrophenyl 2-acetamido-2-deoxy-[alpha]--glucopyranoside, the best inhibitors of the BS II lectin-p-azophenyl 2-acetamido-2-deoxy-[beta]--glucopyranoside--bovine serum albumin conjugate precipitin-system, were 4 times as active as 2-acetamido-2-deoxy--glucopyranose. Of the free monosaccharides tested, 2-acetamido-2-deoxy--glucopyranose was the most potent inhibitor, being over 100 times better than -fructose and 400 times better than -glucose. Comparison of the inhibiting capacity of methyl or p-nitrophenyl 2-acetamido-2-deoxy-[alpha]--glucopyranoside with their corresponding [beta] anomers showed that the [alpha] anomer was bound 6 to 8 times more avidly than the [beta] anomer. Replacement of the C-3, C-4, or C-6 hydroxyl group of -glucose by a methoxyl group or a fluorine atom abolished the capacity of the resulting sugar to bind the BS II lectin, but substitution of the C-2 hydroxyl group of -glucose, by either a methoxyl group or a fluorine group, had no appreciable effect on binding to the lectin. N,N'-Diacetylchitobiose was as active as N,N'N''-triacetylchitotriose, and they were both twice as potent as disaccharides having a nonreducing 2-acetamido-2-deoxy-[alpha]--glucopyranosyl residue. Disaccharides having [beta]--(1 --> 6) glycosidic bonds were very poor inhibitors. Equilibrium-dialysis experiments with p-nitrophenyl 2-acetamido-2-deoxy-[alpha]--glucopyranoside as binding ligand indicated that the BS II lectin possesses approximately one carbohydrate-binding site per subunit for the tetrameric protein (Mr 113,000), with association constants of 1.3 x 105 M-1 at 4[deg], and 0.4 X 105 M-1 at 37[deg].Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22640/1/0000191.pd

Root canal treatment with high-frequency waves in rats

The purpose of this study was to develop a high-frequency wave therapy model in rats and to investigate the influence of high-frequency waves on root canal treatment, which may provide a novel strategy for treating apical periodontitis. Root canal treatments with and without high-frequency wave irradiation were performed on the mandibular first molars of 10-week-old male Wistar rats. The mesial roots were evaluated radiologically, bacteriologically, and immunohistochemically. At 3 weeks after root canal treatment, lesion volume had decreased significantly more in the irradiated group than in the non-irradiated group, indicating successful development of the high-frequency therapy model. The use of high-frequency waves provided no additional bactericidal effect after root canal treatment. However, high-frequency wave irradiation was found to promote healing of periapical lesions on the host side through increased expression of fibroblast growth factor 2 and transforming growth factor-β1 and could therefore be useful as an adjuvant nonsurgical treatment for apical periodontitis

Assessment of the functional efficacy of root canal treatment with high-frequency waves in rats

The purpose of this study was to develop a high-frequency wave therapy model in rats and to investigate the influence of high-frequency waves on root canal treatment, which may provide a novel strategy for treating apical periodontitis. Root canal treatments with and without high-frequency wave irradiation were performed on the mandibular first molars of 10-week-old male Wistar rats. The mesial roots were evaluated radiologically, bacteriologically, and immunohistochemically. At 3 weeks after root canal treatment, lesion volume had decreased significantly more in the irradiated group than in the non-irradiated group, indicating successful development of the high-frequency therapy model. The use of high-frequency waves provided no additional bactericidal effect after root canal treatment. However, high-frequency wave irradiation was found to promote healing of periapical lesions on the host side through increased expression of fibroblast growth factor 2 and transforming growth factor-β1 and could therefore be useful as an adjuvant nonsurgical treatment for apical periodontitis.Assessment of the functional efficacy of root canal treatment with high-frequency waves in rats. Saori Matsui, et al. PLOS ONE. 2020.9(29) doi.org/10.1371/journal.pone.023966

Key factors in achieving firm adhesion in post–core restorations

Adhesive post–core restorations using a combination of fiber reinforced posts (FRPs) and resin composites have become the preferred choice worldwide in restoring pulpless teeth. The success of this method, especially because of the low incidence of root fracture, has been shown in many clinical studies in several countries. However, the method has also shown a tendency for the FRP to come detached from its post-space, and this potential flaw raises questions about the long-term durable prognoses of such restorations. The adhesive characteristics of post–core materials to root canal dentin have been widely investigated as part of the attempt to find a solution to the problem. Comprehensive understanding of the way that root canal dentin behaves in the post-space may be the key to achieving their better adhesion. Clinicians have to contend with the high stresses produced in the post-space because of its extremely high C-factor. When using light-cured and even dual-cured materials, ensuring deep and complete light penetration is essential to obtain even bonding strength throughout the post-space. Chemically cured adhesive materials, where the progress of curing is relatively slow and there is less stress caused by polymerization shrinkage, should be positively considered for the root canal bonding. In every case, careful attention needs to be paid to the negative effects that endodontic irrigation solutions, such as sodium hypochlorite and EDTA, have on root canal adhesion. Even after better adhesion of the FRP to root canal dentin has been achieved—and proved by high-quality long-term clinical studies, the concept of cusp-coverage in pulpless molars may need to be reconsidered based on a good conservative policy of minimal intervention

Interaction of pneumococcal S-14 polysaccharide with lectins from Ricinus communis, Triticum vulgaris, and bandeiraea simplicifolia

Two purified lectins, namely, wheat-germ agglutinin (from Triticum vulgaris) and the hemagglutinin from Ricinus communis seeds, readily form a precipitate with pneumococcal S-14 polysaccharide, whereas the Bandeiraea simplicifolia lectin (BS 1) does not. Exhaustive periodate oxidation and borohydride reduction of S 14 modifies terminal [beta]--galactopyranosyl residues, as well as chain -glucopyranosyl residues, and abolishes reactivity with both the R. communis lectin and wheat-germ agglutinin. Controlled periodate oxidation followed by Smith degradation cleaves only terminal [beta]--galactopyranosyl residues, giving a linear polymer, the structure of which was determined by methylation analysis. This derived polymer, containing (1-->6)-linked 2-acetamido-2-deoxy-[beta]--glucosyl residues, readily precipitated wheat-germ agglutinin, but not the R. communis lectin.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22848/1/0000409.pd

Assessment of Inhibitory Effects of Fluoride-Coated Tubes on Biofilm Formation by Using the In Vitro Dental Unit Waterline Biofilm Model▿

This study aimed to establish an in vitro model to simulate biofilms formed in dental unit waterlines (DUWLs) and to investigate the ability of polyvinylidene fluoride (PVDF)-coated tubes to inhibit biofilm formation using this model. The water and biofilm samples were obtained from DUWLs which had been clinically used for 2.5 years, and the predominant bacteria were identified. A conventional polyurethane tube was incubated for 24 to 96 h in the mixed flora of isolated bacteria, and the optimal incubation conditions to simulate a clinically formed biofilm were determined by observation with a scanning electron microscope. Biofilm formation on a PVDF-coated tube was observed using this in vitro model, and the adherence of different bacterial species to conventional and PVDF-coated tubes was assessed. Sphingomonas paucimobilis, Acinetobacter haemolytics, and Methylobacterium mesophilicum were predominantly isolated from contaminated DUWLs. Incubation of the polyurethane tube with the mixed flora containing these three species for 96 h resulted in the formation of a mature biofilm similar to the one clinically observed. The PVDF-coated tube was significantly less adhesive to all three bacterial species than the polyurethane tube (P < 0.05 by the Mann-Whitney U test), and the attachment of small amounts of rods was observed even after incubation with the mixed flora for 96 h. In conclusion, an in vitro biofilm model was obtained by using a mixed flora of bacteria isolated from DUWLs, and the PVDF-coated tube was found to be effective in preventing biofilm formation using this model

Data from: Statistical analysis for subjective and objective evaluations of dental drill sounds

The sound produced by a dental air turbine handpiece (dental drill) can markedly influence the sound environment in a dental clinic. Indeed, many patients report that the sound of a dental drill elicits an unpleasant feeling. Although several manufacturers have attempted to reduce the sound pressure levels produced by dental drills during idling based on ISO 14457, the sound emitted by such drills under active drilling conditions may negatively influence the dental clinic sound environment. The physical metrics related to the unpleasant impressions associated with dental drill sounds have not been determined. In the present study, psychological measurements of dental drill sounds were conducted with the aim of facilitating improvement of the sound environment at dental clinics. Specifically, we examined the impressions elicited by the sounds of 12 types of dental drills in idling and drilling conditions using a semantic differential. The analysis revealed that the impressions of dental drill sounds varied considerably between idling and drilling conditions and among the examined drills. This finding suggests that measuring the sound of a dental drill in idling conditions alone may be insufficient for evaluating the effects of the sound. We related the results of the psychological evaluations to those of measurements of the physical metrics of equivalent continuous A-weighted sound pressure levels (LAeq) and sharpness. Factor analysis indicated that impressions of the dental drill sounds consisted of two factors: “metallic and unpleasant” and “powerful”. LAeq had a strong relationship with “powerful impression”, calculated sharpness was positively related to “metallic impression”, and “unpleasant impression” was predicted by the combination of both LAeq and calculated sharpness. The present analyses indicate that, in addition to a reduction in sound pressure level, refining the frequency components of dental drill sounds is important for creating a comfortable sound environment in dental clinics

Identification and Localization of Extraradicular Biofilm-Forming Bacteria Associated with Refractory Endodontic Pathogens

Bacterial biofilms have been found to develop on root surfaces outside the apical foramen and be associated with refractory periapical periodontitis. However, it is unknown which bacterial species form extraradicular biofilms. The present study aimed to investigate the identity and localization of bacteria in human extraradicular biofilms. Twenty extraradicular biofilms, used to identify bacteria using a PCR-based 16S rRNA gene assay, and seven root-tips, used to observe immunohistochemical localization of three selected bacterial species, were taken from 27 patients with refractory periapical periodontitis. Bacterial DNA was detected from 14 of the 20 samples, and 113 bacterial species were isolated. Fusobacterium nucleatum (14 of 14), Porphyromonas gingivalis (12 of 14), and Tannellera forsythensis (8 of 14) were frequently detected. Unidentified and uncultured bacterial DNA was also detected in 11 of the 14 samples in which DNA was detected. In the biofilms, P. gingivalis was immunohistochemically detected in all parts of the extraradicular biofilms. Positive reactions to anti-F. nucleatum and anti-T. forsythensis sera were found at specific portions of the biofilm. These findings suggested that P. gingivalis, T. forsythensis, and F. nucleatum were associated with extraradicular biofilm formation and refractory periapical periodontitis