Inhibition of Streptococcus mutans by a commercial yogurt drink.

BACKGROUND/PURPOSE: Studies have been focused on using probiotics to prevent caries. The lactobacillus probiotic bacteria in Yakult® (LcY) has been shown to inhibit the growth or biofilm formation of Streptococcus mutans. However, sucrose in Yakult® raised concerns. The purpose of this study was to determine effects of Yakult® on the growth and adhesion of S. mutans. MATERIALS AND METHODS: S. mutans was grown in serial diluted Yakult®, filtered Yakult® or 20% heated Yakult®. S. mutans was co-cultured with LcY in media with or without diluted filtered Yakult®, or in LcY grown in media with or without sugars. Colony forming units and pH values of bacterial cultures were determined. SYTO 9-stained adhered bacteria were observed. RESULTS: Yakult® inhibited the growth of S. mutans. Filtering or heating Yakult® reduced its inhibitory ability against S. mutans. The inhibitory effect of LcY against S. mutans was enhanced when cultured in the presence of 20% filtered Yakult®. LcY cultured in sucrose media for 24 h inhibited the growth of S. mutans, but this effect was less evident when LcY was grown for 48 h. LcY grown in glucose or lactose media similarly reduced S. mutans growth. Culturing S. mutans with LcY grown in sucrose or glucose media reduced bacterial adhesion. However, co-culturing S. mutans with LcY grown in the lactose media did not decrease bacterial adhesion. CONCLUSION: Yakult® and its probiotic content may inhibit S. mutans growth and the effect may be moderated by the type of sugar added for LcY cultivation.

Inhibitory effects of tea catechin epigallocatechin-3-gallate against biofilms formed from Streptococcus mutans and a probiotic lactobacillus strain.

OBJECTIVE: Effects of tea catechin epigallocatechin-3-gallate (EGCG) against biofilm formation by Streptococcus mutans and probiotic Lactobacillus casei in Yakult® (LcY) were examined. DESIGN: Biofilms were formed by S. mutans alone (Sm) and co-culture of S. mutans and LcY (Sm + LcY) in the absence or presence of EGCG. The biomass of biofilms, which were sonicated or not, was measured by the crystal violet assay. Biofilm morphology was observed by scanning electron microscopy. Bacterial viability and extracellular polysaccharides were determined by SYTO9/propidium iodide and dextran-conjugated fluorescein staining, respectively, and confocal microscopy. Gene expression of glucosyltransferase was determined by quantitative polymerase chain reaction. RESULTS: While 250 µg/ml EGCG significantly decreased the biomass and acid production of Sm biofilms, 500 µg/ml EGCG was required to inhibit Sm + LcY biofilm formation and acid production. EGCG decreased the amount of live bacteria present in both Sm and Sm + LcY biofilms. The level of dead bacteria in Sm + LcY biofilms was higher than in Sm biofilms when formed in the presence of 250 µg/ml EGCG. EGCG decreased levels of extracellular polysaccharides in Sm and Sm + LcY biofilms. The extent of biofilm removal by sonication was not different between Sm and Sm+LcY biofilms formed in the absence or presence of 62.5 or 125 µg/ml EGCG. The level of Sm gtfB and gtfD expression in Sm + LcY biofilms was higher than those in the Sm biofilms when formed in the presence of EGCG at 250 µg/ml. CONCLUSION: The results indicated that LcY might interfere the inhibitory effects of EGCG against biofilm formation by S. mutans.

Antioxidant N-Acetylcysteine and Glutathione Increase the Viability and Proliferation of MG63 Cells Encapsulated in the Gelatin Methacrylate/VA-086/Blue Light Hydrogel System.

Photoencapsulation of cells inside a hydrogel system can provide a suitable path to establish a gel in situ for soft tissue regeneration applications. However, the presence of photoinitiators and blue or UV light irradiation can result in cell damage and an increase of reactive oxygen species. We here evaluate the benefits of an antioxidant pretreatment on the photoencapsulated cells. We study this by evaluating proliferation and viability of MG63 cells, which we combined with a gelatin methacrylate (GelMA) hydrogel system, using the photoinitiator, VA-086, cured with 440 nm blue light. We found that blue light irradiation as well as the presence of 1% VA-086 reduced MG63 cell proliferation rates. Adding a short pretreatment step to the MG63 cells, consisting of the antioxidant molecules N-acetylcysteine (NAC) and reduced glutathione (GSH), and optimizing the GelMA encapsulation steps, we found that both NAC and GSH pretreatments of MG63 cells significantly increased both proliferation and viability of the cells, when using a 15% GelMA hydrogel, 1% VA-086, and 1-min blue light exposure. These findings suggest that the use of antioxidant pretreatment can counteract the negative presence of the photoinitiators and blue light exposure and result in a suitable environment for photoencapsulating cells in situ for tissue engineering and soft tissue applications.

Impact of apurinic/apyrimidinic endonuclease 1/redox factor-1 on treatment response and survival in oral squamous cell carcinoma.

BACKGROUND: Apurinic/apyrimidinic endonuclease 1/redox factor-1 (APE1/Ref-1) is a multifunctional protein involved in DNA repair and redox signaling. The purpose of this study was to investigate the relationship between APE1/Ref-1 expression and clinicopathological features, survival, and treatment response in patients with oral squamous cell carcinoma (OSCC) and cell lines. METHODS: APE1/Ref-1 expression in OSCC was evaluated by immunohistochemistry, and its relationship to patient outcomes and treatment response was assessed statistically. The effects of stable short hairpin (sh)RNA-mediated knockdown of APE1/Ref-1 on cell survival, migration, and chemoradiation sensitivity were determined in OSCC cell lines. RESULTS: APE1/Ref-1 immunostaining was correlated with positive lymph node status, and higher APE1/Ref-1 expression was significantly associated with poor prognosis and reduced treatment response. Consistent with the clinical studies, APE1/Ref-1 expression in OSCC cell lines was implicated in the regulation of migration and cisplatin-induced apoptosis. CONCLUSION: Elevated APE1/Ref-1 expression may be used to predict poor survival and may confer chemoresistance in OSCC.

The hMLH1 -93G>A promoter polymorphism is associates with outcomes in oral squamous cell carcinoma patients.

BACKGROUND: The aim of this study was to investigate the impact of hMLH1 polymorphisms on treatment outcomes in patients with oral squamous cell carcinoma (OSCC). METHODS: Genotypings were performed by direct DNA sequencing in peripheral blood leukocytes from 185 male OSCC patients. Patients received primary surgery with or without adjuvant radiotherapy. Two hMLH1 tag single nucleotide polymorphisms (SNPs)-rs1800734 (-93G>A in the promoter) and rs1540354 (in the third intron)-were chosen from the HapMap project. Overall survival (OS) and disease-free survival (DFS) were compared between different genotypes. RESULTS: The hMLH1 rs1800734 and rs1540354 polymorphisms were in weak linkage disequilibrium (r (2) = 0.456). OSCC patients with the rs1800734 AA genotype had a significantly poor prognosis in both OS and DFS. This SNP can also predict the outcomes of OSCC patients with postoperative adjuvant radiotherapy, especially in advanced stage; however, no significant differences in patient outcomes were found for the hMLH1 rs1540354 genotypes. CONCLUSIONS: Our results demonstrate that the hMLH1 -93G>A SNP is found to be associated with patient outcomes in OSCC. This SNP can also predict their treatment outcome of radiotherapy.

A comparison between adipose tissue and dental pulp as sources of MSCs for tooth regeneration.

In this study, several in vivo and in vitro comparisons were performed to test the possibility of using adipose-derived stem cells (ADSCs), a more convenient cell source than dental pulp stem cells (DPSCs), in tooth regeneration. Using an efficient, non-engineering implantation method, we first demonstrated that both implants of ADSCs and DPSCs were able to grow self-assembled new teeth in adult rabbit extraction sockets with high success rate. The stem cells were necessary because the implants grew no tooth without them. A stepwise comparison showed that the regenerated teeth from these two types of adult stem cells were living with nerves and vascular system and remarkably similar to a normal tooth in many details. Further strictly controlled, side-by-side comparisons between the two types of stem cells also showed that the expression patterns of gene markers and the broad differentiation potentials induced by specific methods in vitro were very similar. Although a few differences were found, they did not affect the tested tooth regeneration in vivo or differentiation in vitro. Furthermore, rabbit ADSCs had a higher growth rate and a better senescence resistance in culture. All these findings suggest that ADSCs, one of the richest adult stem cells in mammals, are very similar and useful as DPSCs for regenerative dentistry.

Loss expression of O6-methylguanine DNA methyltransferase by promoter hypermethylation and its relationship to betel quid chewing in oral squamous cell carcinoma.

OBJECTIVE: O(6)-methylguanine-DNA methyltransferase (MGMT) ameliorates mutagenic, carcinogenic, and cytotoxic adducts from O(6)-methylguanine in DNA through a direct reversal mechanism. Decreased expression of MGMT has been reported in a variety of human malignant tumors. The purpose of this study was to clarify the correlation of MGMT expression levels in oral squamous cell carcinoma (OSCC) with promoter hypermethylation and with betel quid chewing and cigarette smoking. STUDY DESIGN: MGMT protein expression in 63 cases of oral squamous cell carcinoma by immunohistochemistry was investigated. Methylation status of the MGMT was analyzed by methylation-specific PCR. Correlation with clinicopathologic parameters was then tested by statistical analysis. RESULTS: MGMT immunohistochemistry revealed nuclear staining in normal epithelium, whereas 47 (75%) of 63 OSCC tumors were devoid of MGMT expression and this was related to tumor cell differentiation. Furthermore, the association between loss of MGMT expression and promoter hypermethylation was significant. Lacking protein expression for MGMT in OSCC was also associated with the use of betel quid. CONCLUSIONS: The results suggest that the absence of MGMT expression, which would seem to be associated with promoter hypermethylation, is related to betel quid chewing and, thus, in turn, might be a significant event in oral carcinogenesis.