Effectiveness of mentha extracts against oral microorganisms: an in vitro study / 대한구강보건학회지

Objectives@#Dental caries and periodontal disease are infectious and chronic diseases. The aim of the study was to investigate the antimicrobial effect of mentha extracts against Streptococcus mutans (S. mutans ) and Porphyromonas gingivalis (P. gingivalis ). @*Methods@#This activity of mentha extracts were confirmed by the disk diffusion test and minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and colony forming unit (CFU) assays. @*Results@#S. mutans and P. gingivalis showed the highest antimicrobial activity within the inhibition zones. The antimicrobial activity was interrupted as the MIC and MBC of the herbal extracts against the two bacteria were 1 mg/ml and 10 mg/ml, respectively. The antimicrobial effect was determined by the CFU assay. @*Conclusions@#Mentha herb extract demonstrated potential antimicrobial activity against S. mutans and P. gingivalis that cause dental caries and periodontal disease.

Effect of apoptosis on G361 cells by Cimicifuga rhizoma extract / 대한구강보건학회지

OBJECTIVES: To investigate whether the cytotoxic effect of Cimicifuga rhizoma extract is associated with cell death in the human keratinocyte (HaCaT) and human melanoma cell lines (G361). METHODS: Apoptosis induced by Cimicifuga rhizoma extract was confirmed by water-soluble tetrazolium salts-1 (WST-1) assay, immunocytochemistry, and western blot. Additionally, the release of cytochrome c and apoptosis-inducing factor (AIF) was visualized by confocal laser scanning microscopy. RESULTS: The results showed that Cimicifuga rhizoma extract significantly reduced the viability of G361 cells with half-maximal inhibitory concentration (IC 50) of 200 µg/ml, and the apoptotic process was found to occur via the activation of caspase-3 and caspase-9 pathways. Besides, the release of cytochrome c and AIF was also detected. CONCLUSIONS: This study suggests that Cimicifuga rhizoma extract causes apoptosis of human melanoma cells through the intrinsic apoptotic pathway.

Antimicrobial Effect of Low Temperature Atmospheric Plasma against Oral Pathogens

The purpose of this study was to investigate the antibacterial effect of the low temperature atmospheric plasma device with needle tip designed for easy approach to the oral cavity and root canal against Streptococcus mutans, Enterococcus faecalis and Candida albicans. The antibacterial activities evaluated by measuring clear zone of agar plate smeared with each bacteria after plasma treatment. To quantify antibacterial effects, dilution plate method was used. In addition, scanning electron microscope (SEM) was used for observation of changes in bacterial morphology. As treatment time of plasma increased, the clear zone was enlarged. The death rate was more than 99%. The SEM results showed that the globular shape of bacteria was distorted. These results suggest that needle tip plasma could be an innovative device for prevention of dental caries, and treatment of apical infection and soft tissue diseases.

Erratum: Evaluation of the safety of non-thermal atmospheric-pressure plasma in hairless mouse tissues / 대한구강보건학회지

We correct a typo in the title.

Evaluation of the safety of non-thermal atmospheric-pressure plasma in hairless mouse tissues / 대한구강보건학회지

OBJECTIVES: The aim of the present study was to evaluate the stability of non-thermal atmospheric-pressure plasma on Candida albicans in hairless mouse-2 (HRM-2) tissues. METHODS: HRM-2 mice were subjected to non-thermal atmospheric-pressure plasma jet treatment using an optical fiber probe and monitored using a thermometer. The skin of HRM-2 mice was treated with plasma jet for 0, 60, 180, and 300 s per day for 5 days. After plasma treatment, morphological changes in Candida albicans on the skin of these mice were examined using a scanning electron microscope. Biopsy of the plasma-treated skin was performed and the tissues were histologically analyzed using hematoxylin and eosin (H&E) and Masson's trichrome stains. RESULTS: The scanning electron microscopic images revealed the morphological changes in the membrane structure of the plasma-treated Candida albicans. Histological analysis showed that non-thermal plasma treatment did not cause epidermal damage or tissue inflammation and did not significantly modify the collagen layers of the mouse skin. CONCLUSIONS: The results of this study suggest that non-thermal atmospheric-pressure plasma might be safe and effective for clinical applications in the field of dentistry.

Preferential Cytotoxic Effect of Genistein on G361 Melanoma Cells Via Inhibition of the Expression of Focal Adhesion Kinase

Resistance to the induction of apoptosis is a possible mechanism by which tumor cells can survive anti-neoplastic treatments. Melanoma is notoriously resistant to anti-neoplastic therapy. Previous studies have demonstrated focal adhesion kinase (FAK) overexpression in melanoma cell lines. Given its probable role in mediating resistance to apoptosis, many researchers have sought to determine whether the downregulation of FAK in melanoma cells would confer a greater sensitivity to anti-neoplastic agents. Genistein is a known inhibitor of protein-tyrosine kinase (PTK), which may attenuate the growth of cancer cells by inhibiting the PTK-mediated signaling pathway. This present study was undertaken to investigate the effect of genistein on the expression of FAK and cell cycle related proteins in the G361 melanoma cell line. Genistein was found to have a preferential cytotoxic effect on G361 melanoma cells over HaCaT normal keratinocytes. Genistein decreased the expression of 125 kDa phosphotyrosine kinase and the FAK protein in particular. Genistein treatment did not affect the expression of p53 in G361 cells in which p21 is upregulated. The expression of cyclin B and cdc2 was downregulated by genistein treatment. Taken together, our data indicate that genistein induces the decreased proliferation of G361 melanoma cells via the inhibition of FAK expression and regulation of cell cycle genes. This suggests that the use of genistein may be a viable approach to future melanoma treatments.

Pseudomonas aeruginosa Exotoxin A Reduces Chemoresistance of Oral Squamous Carcinoma Cell via Inhibition of Heat Shock Proteins 70 (HSP70)

PURPOSE: Oral squamous carcinoma (OSCC) cells exhibit resistance to chemotherapeutic agent-mediated apoptosis in the late stage of malignancy. Increased levels of heat shock proteins 70 (HSP70) in cancer cells are known to confer resistance to apoptosis. Since recent advances in the understanding of bacterial toxins have produced new strategies for the treatment of cancers, we investigated the effect of Pseudomonas aeruginosa exotoxin A (PEA) on HSP70 expression and induction of apoptosis in chemoresistant OSCC cell line (YD-9). MATERIALS AND METHODS: The apoptotic effect of PEA on chemoresistant YD-9 cells was confirmed by MTT, Hoechst and TUNEL stains, DNA electrophoresis, and Western blot analysis. RESULTS: While YD-9 cells showed high resistance to chemotherapeutic agents such as etoposide and 5-fluorouraci (5-FU), HSP70 antisense oligonucelotides sensitized chemoresistant YD-9 cells to etoposide and 5-FU. On the other hand, PEA significantly decreased the viability of YD-9 cells by deteriorating the HSP70-relating protecting system through inhibition of HSP70 expression and inducing apoptosis in YD-9 cells. Apoptotic manifestations were evidenced by changes in nuclear morphology, generation of DNA fragmentation, and activation of caspases. While p53, p21, and E2F-1 were upregulated, cdk2 and cyclin B were downregulated by PEA treatment, suggesting that PEA caused cell cycle arrest at the G2/M checkpoint. CONCLUSION: Therefore, these results indicate that PEA reduced the chemoresistance through inhibition of HSP70 expression and also induced apoptosis in chemoresistant YD-9 cells.