Exploring the possible applications of catechin (gel) for oral care of the elderly and disabled individuals

SummaryThe oral cavity contains more than hundreds of microbial species. An increase in the number of these microorganisms like high pathogenic potential species, such as cariogenic and periodontopathic bacteria, and the change of microbial biota may result in, not only oral infection, but also systemic diseases, such as infective endocarditis and aspiration pneumonia. It is very important to control the growth of these microorganisms and its biota just after oral cleaning in order to suppress disease onset. In this regard, it is useful to use the anti-microbial component which acts against pathogenic microorganisms. Here, we highlight the importance of catechin, and feature its possible oral, especially periodontal applications. By combining catechin with gel (catechin gel), antimicrobial activity of catechin was prolonged in gel and catechin anti-oxidization property was observed. Catechin gel inhibited the growth of the Actinomyces, periodontopathic bacteria and Candida strains tested, but did not inhibit that of the oral streptococci that are important in the normal oral flora. In contrast, commercially available moisture gels containing antimicrobial components showed antimicrobial activity against all of the tested strains including the oral streptococci. This show that catechin has selective antimicrobial activity, attributable to hydrogen peroxide production. This paper reviews previous works using catechin and, likewise, catechin gel may be show its possible oral application for prevent dental caries and periodontal disease

Structural differences between the avian and human H7N9 hemagglutinin proteins are attributable to modifications in salt bridge formation: a computational study with implications in viral evolution.

Influenza A hemagglutinin (HA) is a homotrimeric glycoprotein composed of a fibrous globular stem supporting a globular head containing three sialic acid binding sites responsible for infection. The H7N9 strain has consistently infected an avian host, however, the novel 2013 strain is now capable of infecting a human host which would imply that the HA in both strains structurally differ. A better understanding of the structural differences between the avian and human H7N9 strains may shed light into viral evolution and transmissibility. In this study, we elucidated the structural differences between the avian and human H7N9 strains. Throughout the study, we generated HA homology models, verified the quality of each model, superimposed HA homology models to determine structural differences, and, likewise, elucidated the probable cause for these structural differences. We detected two different types of structural differences between the novel H7N9 human and representative avian strains, wherein, one type (Pattern-1) showed three non-overlapping regions while the other type (Pattern-2) showed only one non-overlapping region. In addition, we found that superimposed HA homology models exhibiting Pattern-1 contain three non-overlapping regions designated as: Region-1 (S1571-A1601); Region-3 (R2621-S2651); and Region-4 (S2701-D2811), whereas, superimposed HA homology models showing Pattern-2 only contain one non-overlapping region designated as Region-2 (S1371-S1451). We attributed the two patterns we observed to either the presence of salt bridges involving the E1141 residue or absence of the R1411:D771 salt bridge. Interestingly, comparison between the human H7N7 and H7N9 HA homology models showed high structural similarity. We propose that the putative absence of the R1411:D771 salt bridge coupled with the putative presence of the E1141:R2621 and E1141:K2641 salt bridges found in the 2013 H7N9 HA homology model is associated to human-type receptor binding. This highlights the possible significance of HA salt bridge formation modifications in viral infectivity, immune escape, transmissibility and evolution

S-PRG Filler Eluate Induces Oxidative Stress in Oral Microorganism: Suppression of Growth and Pathogenicity, and Possible Clinical Application

Controlling the oral microbial flora is putatively thought to prevent not only oral diseases, but also systemic diseases caused by oral diseases. This study establishes the antibacterial effect of the novel bioactive substance “S-PRG filler” on oral bacteria. We examined the state of oxidative stress caused by the six types of ions released in eluate from the S-PRG filler in oral bacterial cells. Moreover, we investigated the effects of these ions on the growth and pathogenicity of Gram-positive and Gram-negative bacteria. We found that the released ions affected SOD amount and hydrogen peroxide in bacterial cells insinuating oxidative stress occurrence. In bacterial culture, growth inhibition was observed depending on the ion concentration in the medium. Additionally, released ions suppressed Streptococcus mutans adhesion to hydroxyapatite, S. oralis neuraminidase activity, and Porphyromonas gingivalis hemagglutination and gingipain activity in a concentration-dependent manner. From these results, it was suggested that the ions released from the S-PRG filler may suppress the growth and pathogenicity of the oral bacterial flora. This bioactive material is potentially useful to prevent the onset of diseases inside and outside of the oral cavity, which in turn may have possible applications for oral care and QOL improvement

H7N9 human HA homology model has two patterns of structural differences with avian HA homology models.

<p>H7N9 HA homology model superimposition of the (A) 2008b and 2011 strains, (B) 2011 and 2013 strains, and (C) 2008b and 2013 strains. HA homology models of the 2008b (gray), 2011 (blue), and 2013 (pink) strains are shown. Non-overlapping regions representing structural differences (shaded in gray) are indicated. RMSD scores of the superimposed Cα backbone are indicated below. RMSD scores close to 0 would insinuate low structural difference between the homology models.</p

Quality estimation of influenza A H7N9 hemagglutinin homology models generated.

<p>Ribbon structure and model quality estimation of a (A) representative avian and (B) novel human H7N9 HA homology models. QMEAN score is indicated below. QMEAN scores > 0.5 are considered reliable. α-helix (red), ß-sheet (yellow), and structural loops (white) are indicated.</p

Pattern-1 structural differences are ascribable to salt bridge formation involving amino acid residue 114₁.

<p>Distance measurements of amino acid residues 262₁, 264₁, and 265₁ (green) relative to residue 114₁ (violet) found in the (A) 2011 and (B) 2013 HA homology models. All amino acid residues indicated are in a wireframe structure. All measurements are indicated in Å. Interrelationship of HA structural differences (shaded in gray) observed in the (C,E) 2011 and (D,F) 2013 HA homology models are highlighted in green. Amino acid residue 114₁ is indicated in violet.</p

Post-weaning increases in the milk-fat globule EGF-factor VIII on fat globules in mouse milk and in the uptake of the fat globules by HC11 mammary epithelial cells

Milk fat globules (MFGs) secreted by lactating mammary gland are unique lipid surrounded by a phospholipid bi-layer. We report here post-weaning changes in milk fat globule EGF factor VIII (MFG-E8) and annexin V-accessible phosphatidylserine on the surface of MFGs. The MFG content in milk markedly decreased to about half within 2 days after forced weaning, despite a slight increase in milk protein content. Immunofluorescence-staining of MFGs using anti-MFG-E8 and annexin V indicated that MFG-E8 was present on some, but not all, MFGs before weaning, whereas most of MFGs were MFG-E8-positive and annexin V-negative after weaning. Free MFG-E8 with binding activity to phosphatidylserine was present abundantly in the post-weaning milk, and indeed exhibited binding to MFGs in pre-weaning milk. MFGs were taken up by HC11 mouse mammary epithelial cells in vitro, and those from post-weaning milk were remarkable for such cellular uptake. Moreover, the uptake of MFGs by the cells was inhibited by an anti-MFG-E8 antibody. Taken together, these findings suggest that MFG-E8 plays a critical role in regulation of MFG dynamics after weaning or during the suckling interval through the control of MFG-epithelial cell interaction in lactating mammary glands