To evaluate the biohazard properties of an extremely low frequency electromagnetic field (ELF-EMF), we explored the physical properties of the ELF-EMF that generates the electric current induction in the secondary coil from the chamber of a primary solenoid coil. We subsequently explored the biological effects of a strong alternating electromagnetic field (EMF), ranging from 730-960 Gauss, on the mouse testis. Mice were exposed to an alternating EMF field induced by a rectangular electric current at 1, 7, 20, 40, and 80 Hertz, for 1, 3, 5, and 7 hours. The mouse testes were examined for proliferative activity and apoptosis using the in situ terminal deoxynucleotidyl transferase (TdT) method and by immunostaining of proliferating cell nuclear antigen (PCNA), respectively. We found that the electric currentm induction increased in the 6-8 Hertz range, and that exposure to an ELF-EMF induced the apoptosis of mouse spermatocytes. In situ TdT staining was found to be most prominent in 7 Hertz group, and gradually reduced in the 20, 40, and 80 Hertz groups. These data suggest that a strong EMF can induce reproductive cell death within a short time, and the harmful effects of the EMF are maximal at low frequency alternating EMFs.

Periodontitis is an inflammatory disorder of the periodontium and is characterized by destruction of the tooth supporting tissues, mediated by the upregulation of synthesis and release of a variety of pro-inflammatory factors. Inflammatory cytokines and prostaglandins upregulate RANKL and its subsequent binding to RANK stimulates osteoclast formation, resorption activity, and survival. In our present study, we investigated the effects of HP08-0111, composed of Coptis japonica (Thunb.) Makino, vitamin C and vitamin E, upon inflammatory responses, osteoclastogenesis and alveolar bone loss. HP08-0111 decreased the expression of IL-1$\beta$ and COX2 on LPS-induced RAW 264.7 cells and inhibited osteoclast-specific genes such as c-Fos, MMP-9, and TRAP. HP08-0111 also exhibited protective effects against alveolar bone loss in rats with ligature-induced periodontitis. Our results suggest that HP08-0111 is potentially an important therapeutic tool for the treatment of disorders associated with bone loss such as periodontitis.

Angelica decursiva has been used in Korean traditional medicine as an antitussive, an analgesic, an antipyretic and a cough remedy. However, the anti-cancer properties of Angelica decursiva have not yet been well defined. In our current study the cytotoxic activity of ethanol extracts of Angelica decursiva root (EEAD) and the mechanism of cell death exhibited by EEAD were examined in FaDu human head and neck squamous cell carcinoma cells. The cytotoxic effects of EEAD upon the growth of FaDu cells were examined with an MTT assay. In addition, the mechanism of cell death induced by EEAD was evaluated by DNA fragmentation analysis, immunoblotting and caspase activation measurements. EEAD induced apoptotic cell death in FaDu cells in a concentration- and time-dependent manner, as determined by MTT assay and DNA fragmentation analysis. Furthermore, the proteolytic processing of caspase-3, -7 and -9 was increased by EEAD treatment of FaDu cells. In addition, the activation of caspase-3 and -7 was detected in living FaDu cells by fluorescence microscopy. These results suggest that EEAD can induce apoptosis and suppress cell growth in cancer cells and may have utility as a future anticancer therapy.

To provide a basis for studying the pharmacological actions of tetracaine HCl, we analyzed the membrane activities of this local anesthetic. The n-(9-anthroyloxy) stearic and palmitic acid (n-AS) probes (n = 2, 6, 9, 12 and 16) have been used previously to examine fluorescence polarization gradients. These probes can report the environment at a graded series of depths from the surface to the center of the membrane bilayer structure. In a dosedependent manner, tetracaine HCl decreased the anisotropies of 6-AS, 9-AS, 12-AS and 16-AP in the hydrocarbon interior of synaptosomal plasma membrane vesicles isolated from bovine cerebral cortex (SPMV), and liposomes derived from total lipids (SPMVTL) and phospholipids (SPMVPL) extracted from the SPMV. However, this compound increased the anisotropy of 2-AS at the membrane interface. The magnitude of the membrane rotational mobility reflects the carbon atom numbers of the phospholipids comprising SPMV, SPMVTL and SPMVPL and was in the order of the 16, 12, 9, 6, and 2 positions of the aliphatic chains. The sensitivity of the effects of tetracaine HCl on the rotational mobility of the hydrocarbon interior or surface region was dependent on the carbon atom numbers in the descending order 16-AP, 12-AS, 9-AS, 6-AS and 2-AS and on whether neuronal or model membranes were involved in the descending order SPMV, SPMVPL and SPMVTL.

Cholinesterase (ChE) is one of the most ubiquitous enzymes and in addition to its well characterized catalytic function, the morphogenetic involvement of ChE has also been demonstrated in neuronal tissues and in non-neuronal tissues such as bone and cartilage. We have previously reported that during mouse tooth development, acetylcholinesterase (AChE) activity is dynamically localized in the dental epithelium and its derivatives whereas butyrylcholinesterase (BuChE) activity is localized in the dental follicles. To test the functional conservation of ChE in tooth morphogenesis among different species, we performed cholinesterase histochemistry following the use of specific inhibitors of developing molar and incisors in the hamster from embryonic day 11 (E11) to postnatal day 1 (P1). In the developing molar in hamster, the localization of ChE activity was found to be very similar to that of the mouse. At the bud stage, no ChE activity was found in the tooth buds, but was first detectable in the dental epithelium and dental follicles at the cap and bell stages. AChE activity was found to be principally localized in the dental epithelium whereas BuChE activity was observed in the dental follicle. In contrast to the ChE activity in the molars, BuChE activity was specifically observed in the secretory ameloblasts of the incisors, whilst no AChE activity was found in the dental epithelium of incisors. The subtype and localization of ChE activity in the dental epithelium of the incisor thus differed from those of the molar in hamster. In addition, these patterns also differed from the ChE activity in the mouse incisor. These results strongly suggest that ChE may play roles in the differentiation of the dental epithelium and dental follicle in hamster, and that morphogenetic subtypes of ChE may be variable among species and tooth types.

In our present study, we investigated the effects of continentalic acid on Streptococcus mutans (S. mutans) biofilm. Methanol extract of Aralia continentalis (A. continentalis) was suspended in water and sequentially partitioned with CHCl3, ethyl acetate (EtOAc), and n-butanol (n-BuOH). The CHCl3 fraction showed the highest activity and an antibacterial compound against S. mutans was isolated from this preparation through various chromatography methods by bioassay guided fractionation. MS, $^1H-NMR$ and $^{13}C-NMR$ analysis showed that the active principle was continentalic acid which was confirmed to show significant inhibitory effects against S. mutans biofilm. These results may provide some scientific rationale for the traditional use these extracts for the treatment of dental diseases.

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most prevalent pathogens in hospitals. To investigate cross contamination by this bacterium in both dental and medical settings, the pathogens that cause acute pyogenic infection and one of the major microbes responsible for nosocomial infection were isolated from health care providers, nurses and patients. We used VITEK II to measure drug sensitivity, and we further performed biochemical testing, coagulase serotype testing and pulse-field gel electrophoresis (PFGE) for isolated MRSA colonies. The isolation rate of Staphylococcus aureus from nasal swabs was 75.0% from dental health care providers and 18.8% from the medical health care providers. A total of 10 MRSA strains were isolated from 40 health care providers and 2 patients and the prevalent coagulase serotype from patients and health care providers was VII. The antimicrobial drug resistance and partial PFGE types of the isolated MRSA strains showed a similar pattern. These results suggest that MRSA may be one of the principal causes of nosocomial infection in dental and medical hospitals.

Oleanolic acid is a natural triterpenoid that exists widely in foods and some medicinal herbs. The purpose of this study was to determine the antimicrobial activity of oleanolic acid against Streptococcus mutans strains isolated from a Korean population. Antimicrobial activity against these bacteria was evaluated by minimal inhibitory concentration (MIC) and time kill curves. The tolerance of human gingival fibroblasts and human periodontal ligaments to oleanolic acid was tested using a methyl thiazolyl tetrazolium (MTT) assay. The $MIC_{90}$ value of oleanolic acid for both S. mutans and S. sobrinus isolated from Koreans was 8 ${\mu}g/ml$. Oleanolic acid showed bactericidal effects against S. mutans ATCC $25175^T$ and S. sobrinus ATCC $33478^T$ at $1\;{\times}\;MIC$ ($8{\mu}g/ml$) and had no cytotoxic effects against KB cells at this dose. The results suggest that oleanolic acid could be useful in the future development of oral hygiene products for the prevention of dental caries.

Most oral microorganisms exist as biofilms which initiate formation via the attachment of an early colonizer to host proteins on the tooth surface. Fusobacterium nucleatum act as a bridge between early and late colonizers. Dental biofilms eventually comprise dental pathogens such as Porphyromonas gingivalis, Treponema denticola and Tannerella forsythia. To evaluate the effects of mutual interactions between oral bacteria on the growth of biofilms, periodontopathogens were co-cultured with a $0.4\;{\mu}m$ barrier. Streptococcus gordonii inhibited the growth of F. nucleatum and periodontopathogens. However, F. nucleatum, P. gingivalis and T. denticola activated the growth of other bacteria. A co-culture system of early and late colonizers could be a useful tool to further understand bacterial interactions during the development of dental biofilm.

A number of bacterial species coexist in oral cavities as a biofilm rather than a planktonic arrangement. By forming an oral biofilm with quorum sensing properties, microorganisms can develop a higher pathogenic potential and stronger resistance to the host immune system and antibiotics. Hence, the inhibition of biofilm formation has become a major research issue for the future prevention and treatment of oral diseases. In this study, we investigated the effects of pentose on biofilm formation and phenotypic changes using wild type oral bacteria obtained from healthy human saliva. D-ribose and D-arabinose were found to inhibit biofilm formation, but have no effects on the growth of each oral bacterium tested. Pentoses may thus be good candidate biofilm inhibitors without growth-inhibition activity and be employed for the future prevention or treatment of oral diseases.

Cells that have endogenous multipotent properties can be used as a starting source for the generation of induced pluripotent cells (iPSC). In addition, small molecules associated with epigenetic reprogramming are also widely used to enhance the multi- or pluripotency of such cells. Skinderived precursor cells (SKPs) are multipotent, sphereforming and embryonic neural crest-related precursor cells. These cells can be isolated from a juvenile or adult mammalian dermis. SKPs are also an efficient starting cell source for reprogramming and the generation of iPSCs because of the high expression levels of Sox2 and Klf4 in these cells as well as their endogenous multipotency. In this study, valproic acid (VPA), a histone deacetylase (HDAC) inhibitor, was tested in the generation of iPSCs as a potential enhancer of the reprogramming potential of SKPs. SKPs were isolated from the back skins of 5-6 week old C57BL/6 X DBA/2 F1 mice. After passage 3, the SKPs was treated with 2 mM of VPA and the quantitative real time RT-PCR was performed to quantify the expression of Oct4 and Klf4 (pluripotency specific genes), and Snai2 and Ngfr (neural crest specific genes). The results show that Oct4 and Klf4 expression was decreased by VPA treatment. However, there were no significant changes in neural crest specific gene expression following VPA treatment. Hence, although VPA is one of the most potent of the HDAC inhibitors, it does not enhance the reprogramming of multipotent skin precursor cells in mice.

Angelica decursiva has been used in Korean traditional medicine as an antitussive, an analgesic, an antipyretic and a cough remedy. However, its anti-cancer properties have not yet been well defined. In our current study, we report the cytotoxic activity and the mechanism of cell death induced by ethanol extracts of Angelica decursiva (EEAD) against the human oral cancer cell line, KB. Treatment of KB cells with EEAD induced apoptotic cell death in both a dose- and time-dependent manner as determined by MTT assay and DNA fragmentation. However, no cytotoxic effects of EEAD against human normal oral keratinocytes (HNOK) were evident. By western blot analysis, we found that apoptosis in KB cells is associated with a decrease in procaspase-7 and -9. In addition, the activation of caspase-7 was detectable in living KB cells by fluorescence microscopy. These results suggest that EEAD exhibits anti-cancer activity in KB cells via apoptosis and thus has potential as an anticancer agent in future drug development strategies.