Yoshinori Takaesu

Reduction of Streptococcus mutans Adherence and Dental Biofilm Formation by Surface Treatment with Phosphorylated Polyethylene Glycol

ABSTRACT Initial attachment of the cariogenic Streptococcus mutans onto dental enamel is largely promoted by the adsorption of specific salivary proteins on enamel surface. Some phosphorylated salivary proteins were found to reduce S. mutans adhesion by competitively inhibiting the adsorption of S. mutans-binding salivary glycoproteins to hydroxyapatite (HA). The aim of this study was to develop antiadherence compounds for preventing dental biofilm development. We synthesized phosphorylated polyethylene glycol (PEG) derivatives and examined the possibility of surface pretreatment with them for preventing S. mutans adhesion in vitro and dental biofilm formation in vivo. Pretreatment of the HA surface with methacryloyloxydecyl phosphate (MDP)-PEG prior to saliva incubation hydrophilized the surface and thereby reduced salivary protein adsorption and saliva-promoted bacterial attachment to HA. However, when MDP-PEG was added to the saliva-pretreated HA (S-HA) surface, its inhibitory effect on bacterial binding was completely diminished. S. mutans adhesion onto S-HA was successfully reduced by treatment of the surface with pyrophosphate (PP), which desorbs salivary components from S-HA. Treatment of S-HA surfaces with MDP-PEG plus PP completely inhibited saliva-promoted S. mutans adhesion even when followed by additional saliva treatment. Finally, mouthwash with MDP-PEG plus PP prevented de novo biofilm development after thorough teeth cleaning in humans compared to either water or PP alone. We conclude that MDP-PEG plus PP has the potential for use as an antiadherence agent that prevents dental biofilm development.

Statherin and histatin 1 reduce parotid saliva-promoted Streptococcus mutans strain MT8148 adhesion to hydroxyapatite surfaces.

Small salivary phosphoproteins – statherin (ST) and histatin 1 (HT1) – are found in the acquired enamel pellicle which modulates Streptococcus mutans adhesion onto dental enamel. However, their roles in S. mutans adhesion onto enamel surfaces are still undefined. The aim of this study was to investigate whether and how ST and HT1 affect (i) S. mutans adhesion and (ii) the adsorption of S. mutans adhesion-promoting salivary proteins onto hydroxyapatite (HA) in vitro. We fractionated human parotid saliva by adsorption to HA and further by gel filtration chromatography. Adhesion of [3H]-labeled S. mutans strain MT8148 onto sintered HA plates was promoted significantly (>10-fold) by high-molecular weight glycoprotein fraction (HMWGP), but not by purified ST or HT1. More interestingly, promotion of S. mutans adhesion onto HA by HMWGP was significantly reduced by adding purified ST or HT1 to HMWGP. [3H]-labeled S. mutans adhesion on HA was positively correlated to the [14C]-labeled HMWGP adsorption onto HA, which was also reduced by the addition of purified ST and HT1. Synthetic peptides corresponding to ST and HT1 reduced the parotid saliva-promoted S. mutans adhesion. However, removal of the negative charges in the N-terminal domains of ST and HT1 diminished their inhibitory effects on S. mutans adhesion promoted by parotid saliva. We conclude that ST and HT1 competitively inhibit the adsorption of salivary HMWGP, and thereby reduce S. mutans adhesion onto HA surfaces.

Saliva-Promoted Adhesion of Streptococcus mutans MT8148 Associates with Dental Plaque and Caries Experience

Colonization of enamel surfaces by Streptococcus mutans is thought to be initiated by the attachment of bacteria to a saliva-derived conditioning film (acquired pellicle). However, the clinical relevance of the contribution of saliva-promoted S. mutans adhesion in biofilm formation has not yet been fully elucidated. The aim of this study was to correlate saliva-promoted S. mutans adhesion with biofilm formation in humans. We correlated all measurements of salivary factors and dental plaque formation in 70 healthy subjects. Dental plaque development after thorough professional teeth cleaning correlated positively with S. mutans adhesion onto saliva-coated hydroxyapatite pellets and the glycoprotein content of either parotid or whole saliva. Saliva-promoted S. mutans adhesion and glycoprotein content were also positively correlated with each other in parotid and whole saliva. By contrast, neither salivary mutans streptococci, Lactobacillus nor Candida correlated with biofilm formation. Parotid saliva-mediated S. mutans adhesion was significantly higher in 12 caries-experienced (CE) subjects than in 9 caries-inexperienced (CI) subjects. Salivary S. mutans adhesion was significantly less (p < 0.01) in the CI group than in the CE group. In conclusion, the present findings suggest the initial S. mutans adhesion, modulated by salivary protein adsorption onto the enamel surface, as a possible correlate of susceptibility to dental plaque and caries.

Reduction of saliva-promoted adhesion of Streptococcus mutans MT8148 and dental biofilm development by tragacanth gum and yeast-derived phosphomannan

Abstract The aim of this study was to investigate materials which reduce saliva-promoted adhesion of Streptococcus mutans onto enamel surfaces, and their potential in preventing dental biofilm development. The effects of hydroxyapatite (HA) surface pretreatment with hydrophilic polysaccharides on saliva-promoted S. mutans adhesion in vitro and de novo dental biofilm deposition in vivo were examined. Saliva-promoted adhesion of S. mutans MT8148 was significantly reduced by pretreatment of the HA surface with tragacanth gum (TG) and yeast-derived phosphoglycans. Extracellular phosphomannan (PM) from Pichia capsulata NRRL Y-1842 and TG reduced biofilm development on lower incisors in plaque-susceptible rats when administered via drinking water at concentrations of 0.5% and 0.01%, respectively. The inhibitory effect of TG on de novo dental biofilm formation was also demonstrated when administered via mouthwash in humans. It is concluded that TG and yeast-derived PM have the potential for use as anti-adherent agents and are effective in reducing de novo dental biofilm formation.

Effects on acute organophosphorus poisoning in rats in aging and solubility of organophosphates.

Various organophosphorus compounds with low acute toxicity are predominantly used as insecticides worldwide. Human acute organophosphorous poisoning often occurs as a result of accidental, criminal or suicidal ingestion. We determined the effect of rat age and lipid solubility of organophosphates on acute organophosphorus poisoning.After trichlorfon with high water solubility was administered to rats, it and its metabolite, dichlorvos, rapidly disappeared from blood, liver, kidneys and fat-tissues, and the ChE activity in the serum, erythrocytes and brain was rapidly normalized. Dichlofenthion disappeared very slowly from poisoned rats due to its fat-solubility. ChE activity was inhibited for a long time by dichlofenthion released from adipose reservoirs in the whole body, especially in 40-week-old rats, and normal and obese rats at 80 weeks of age. Three-week-old rats, which were at a sexually immature developmental stage, showed mild symptoms of dichlofenthion poisoning. By contrast, 7-week-old rats were poisoned most severely with dichlofenthion and their ChE activity was the most severely inhibited among 3-, 7-, 40-and 80-week-old rats. The recovery of ChE activity in rats poisoned with fenitrothion was the most protracted because of the rapid aging of ChE phosphorylated by fenitrothion, although fenitrothion disappeared more rapidly from rat tissues than dichlofenthion.These findings in rats demonstrated that the pattern of recovery and the degree of symptoms of acute organophosphorus poisoning differed with age and the organophosphate.

Adhesiveness of Foods and Their Retention in the Mouth

食品の齲蝕誘発能は, 食品の齲蝕誘発病に与える基質としての性質と, その基質としての性質の作用時間とで評価することが, 可能であることを著者らは提唱してきた。本報では, 食品の物理的性状によって影響されると考えられる食品の作用時間としての性質を測定することをその目的とした。食品の作用時間としての性質は, 摂取中の作用時間と嚥下後の作用時間とに分けられ, 前者は, 食品単位重量あたりの摂取時間で, 後者は, 食品の付着性を23種の食品について測定し, その結果から, 食品の物理的性状よりその齲蝕誘発能を評価する方法について次のような考察を得た。1) 従来の報告で食品の作用時間としての性質が正しく評価されていない種類の食品についても, 食品の作用時間としての性質を二つに分けて行なう本研究方法によって, その評価が可能であることが明らかとなった。2) 本研究方法は, 従来の方法と比較して簡単であり, 被験者間の個人差もみられない。3) レオメーターによる食品の物理的性状の測定は, 齲蝕誘発能の評価のための指標として有用であることが, 示唆された。