• 한국환경성돌연변이발암원학회지
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• 제19권1호
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• pp.46-55
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• 1999

To develop a chemopreventive strategy based on the different stages of premalignant lesions, we hypothesized that the inhibitory effect of chemopreventive agents is influenced by different promotion stages during carcinogenesis. DMBA-TPA-induced skin carcinogenesis was used with ICR mice and chlorophyllin (CHL) was applied as a chemopreventive agent. In vitro assay was performed with Salmonella typhi. TA100 to observe any anti-mutagenic activity of CHL against DMBA. Pre-initiation and pre-promotion effects of CHL were observed by CHL treatment before initiation and before promotion. To evaluate the inhibitory effect at different promotion stages, each group was divided into three subgroups after TPA promotion for 6, 18 and 24 weeks, respectively ; the first subgroup was immediately sacrificed after termination of TPA, the second subgroup was treated with CHL, and the third subgroup was sacrificed 8 weeks after termination of TPA without CHL treatment. The degrees of epithelial dysplasia, papilloma formation, and invasive carcinoma were observed histologically, and GST-Pi expression was observed immunohistochemically. ODC mRNA level was analyzed by reverse transcriptase-polymerase chain reaction. Results showed : CHL dose-dependently inhibited the mutation of Salmonella typhi. TA100; the incidence of epithelial dysplasia and papilloma formation was lower in pre-initiation and pre-promotion CHL-treated mice than DMBA-TPA-treated mice; no invasive carcinoma developed in pre-initiation CHL-treated groups, while 67% of DMBA-TPA treated mice had carcinomas; GST-Pi expression decreased when CHL was treated before initiation and before promotion; and when CHL was treated after termination of TPA application at 18 and 24- week-TPA promotion stages, respectively, the incidence of epithelial dysplasia and papilloma was markedly reduced compared to non-treated groups. When comparing the incidence of epithelial dysplasia and papilloma between the immediately-sacrificed subgroup and the non-treated group with a waiting period, we speculated that the 18-week-TPA promotion stage might belong to the promoter-independent progression stage. At the 18-week-TPA promotion stage, the level of ODC mRNA in the CHL-treated group was clearly reduced to the level of normal tissue. Taking these results together, CHL showed both anti-initiation and anti-promotion effects, while the inhibitory effect of CHL was prominent in the 18-week-TPA promotion stage. However, CHL seems to be incapable of completely blocking the progression in the 24-week-TPA promotion stage.

• International Journal of Oral Biology
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• 제36권2호
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• pp.51-57
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• 2011

Runx2 and Osterix, the transcription factors for osteoblast differentiation, are known as fundamental factors to regulate the development of calcified tissues. However, the biological functions of these factors in the development of the periodontal tissues remain unclear. In this study, we investigated the distribution of Runx2 and Osterix during periodontal tissue development of the mice. Mandibles from 14-day-old mice were prepared for paraffin section. Serial sections of the mandible containing $1^{st}$ molar tooth germs were obtained as a thickness of $7\;{\mu}m$. Some sections were stained with hematoxylin and eosin. Others were used for immunohistochemistry for PCNA, Runx2, and Osterix. Epithelial cells in growing end of Hertwig's epithelial root sheath (HERS) and mesenchymal cells adjacent to the growing end of HERS expressed PCNA. Undifferentiated mesenchymal cells and hard tissue forming cells like cementoblasts and osteoblasts in early stage of differentiation expressed Runx2. Fully differentiated cementoblasts and osteoblasts secreting matrix proteins expressed Osterix. However, the cells terminated the matrix formation did not express Osterix. Periodontal ligament cells expressed Runx2 and Osterix. Pulp cells expressed Runx2 only. These results suggest that Runx2 and Osterix might regulate the differentiation of cementoblasts in the same manner as osteoblasts. Runx2 might participate in the process of cementoblast differentiation in early stage, whether Osterix might regulate the maturation and matrix synthesis of the cells.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제27권5호
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• pp.438-445
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• 2005

Cyclosporine A(CsA) is a powerful immunossuppresive agent used to prevent graft rejection of organ and treat autoimmune disease. One of the major side effects associated with CsA treatment is the development of gingival overgrowth. The purpose of this study was to evaluate the expression and association of the several growth factors in gingival overgrowth induced CsA using by immunohistochemical technique. Normal tissues as control were obtained from healthy normal gingivae and overgrowth gingival tissues as experiments were obtained from the patients taken the CsA. The expressions of the MMP-1, TIMP-1, TGF$\beta$-1, p21, p53, PCNA were evaluated by immunohistochemical technique. The more overgrowth was detected at the epithelial and connective tissue area in experimental group. The MMP-1, TGF$\beta$-1, p21, p53, PCNA expressions were significantly increased in experimental group. The TIMP-1 expressions was not significantly increased in experimental group. We could conclude that the gingival overgrowth induced CsA was related with the collagen matabolism in connective tissue and also the production of the growth factor from epithelial tissue.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제35권2호
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• pp.73-81
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• 2013

Purpose: Smad4 is a central mediator for transforming growth factor-${\beta}$/bone morphogenetic protein ($TGF-{\beta}/BMP$) signals, which are involved in regulating cranial neural crest cell formation, migration, proliferation, and fate determination. Accumulated evidences indicate that $TGF-{\beta}/BMP$ signaling plays key roles in the early tooth morphogenesis. However, their roles in the late tooth formation, such as cellular differentiation and matrix formation are not clearly understood. The objective of this study is to understand the roles of Smad4 in vivo during enamel and dentin formation through tissue-specific inactivation of Smad4. Methods: We generated and analyzed mice with dental epithelium-specific inactivation of the Smad4 gene (K14-Cre:$Smad4^{fl/fl}$) and dental mesenchyme-specific inactivation of Smad4 gene (Osr2Ires-Cre:$Smad4^{fl/fl}$). Results: In the tooth germs of K14-Cre:$Smad4^{fl/fl}$, ameloblast differentiation was not detectable in inner enamel epithelial cells, however, dentin-like structure was formed in dental mesenchymal cells. In the tooth germs of Osr2Ires-Cre:$Smad4^{fl/fl}$ mice, ameloblasts were normally differentiated from inner enamel epithelial cells. Interestingly, we found that bone-like structures, with cellular inclusion, were formed in the dentin region of Osr2Ires-Cre:$Smad4^{fl/fl}$ mice. Conclusion: Taken together, our study demonstrates that Smad4 plays a crucial role in regulating ameloblast and odontoblast differentiation, as well as in regulating epithelial-mesenchymal interactions during tooth development.

• Journal of Periodontal and Implant Science
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• 제38권4호
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• pp.691-698
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• 2008

Purpose: Periodontal pathogens can invade the host tissue. Morphologic studies have revealed bacteria within the pocket epithelium, gingival connective tissues, alveolar bone, and oral epithelium. The objective of this study was to visualize and evaluate presence of Porphyromonas gingivalis and Tannerella forsythia in crevicular epithelial cells of periodontally healthy subjects and chronic periodontitis patients. Materials and Methods: A total of 666 crevicular epithelial cells in the samples obtained from 27 chronic periodontitis patients and 9 healthy volunteers were examined. Specific probes for P. gingivalis and T. forsythia and a universal probe for detection of all eubacteria targeting 168 rRNA for fluorescence in situ hybridization was used in conjunction with confocal laser scanning microscopy. Results: 98.99% of sulcular epithelial cells from healthy volunteers and 84.40% of pocket epithelial cells from periodontitis patients were found to harbor bacteria. P. gingivalis and T. forsythia were discovered more often in crevicular epithelial cells from periodontitis patients. Conclusion: P. gingivalis and T. forsythia can invade crevicular epithelial cells and intracellular bacteria may act as a source of bacteria for persistent infection.

• Restorative Dentistry and Endodontics
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• 제11권1호
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• pp.89-95
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• 1985

The intact dental pulps which were free of their tooth bud from adult rat incisors, and oral mucosa were transplanted subcutaneously in homologous rats to study the formation of calcified tissue. The rat were sacrificed after 1,2,3 and 4 weeks following transplantation of dental pulp and oral mucosa. The samples which contained the transplanted and surrounding tissue were fixed in 10% NBF, stained with hematoxylin and eosin, alizarin red S, von Kossa, and alcian blue. Microscopic examinstins revealed as follows: 1. The transplanted oral mucosas were not calcified but tended to form the epithelial cysts. 2. At 1 week after transplantation of dental pulp the calcified structures were appeared at the periphery of the transplantation of dental pulp but weakly reacted to alizarin red S, von Kossa, and alcian blue. 3. At 2 weeks after transplantation of dental pulp the calcified structures began to expand from the periphery to the center of the transplanted dental pulp and occupied the large areas comparatively, and strongly reacted to alizarin red S, and von Kossa stains. 4. At 3 weeks after transplantation of pulp tissue the fibrous components were grown at the periphery of the transplanted pulp tissuesand at 4 weeks a large amount of fibrous tissues were observed. The transplanted pulp tissue tended to form foreign bodies gradually.

• 한국동물학회:학술대회논문집
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• 한국동물학회 2003년도 한국생물과학협회 학술발표대회
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• pp.160.2-160
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• 2003

No Abstract, See Full Text

• 대한치과의사협회지
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• 제11권12호
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• pp.783-786
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• 1973

The healing response may very with the tissue, the site and the degree of wound. the author observed histochemically the epithelial regeneration in the har palate wound of healthy male albino rats, varying in age from 120 to 150 days, and weighing about 100 gm. The deep wounds were made antero-posterior linealy by surgical knife to the depth of bone level. They were sacrified by ether anesthesia on 1, 2, 4, 7, 10 and 14 days after wounding. the staining methods used were Mcmanus' PAS reaction, Mowry's modification of the Hale reaction employing Muller's colloidal iron reagent, alloxan-Schiff reaction and hematoxylin-eosin stain. The results were as follows : 1. In the wound healing of hard palate, the epithelium had marked PAS positive reaction in the granular and the prickle cell layers on the from 2nd to 7th day. 2. Alloxan-Schiff reactions of regenerated epithelium were slightly increased on 7th day.

• 대한치과의사협회지
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• 제52권12호
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• pp.726-733
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• 2014

The gingiva consists of an epithelial layer and an underlying connective tissue layer. The oral epithelium is a keratinized, stratified, squamous epithelium. The epithelium can be divided into the following cell layer: basal layer, prickle cell layer, granular cell layer and keratinized cell layer. The desquamative disease of gingiva means exfoliative diseases of epithelial layer on the gingiva. The chronic desqumative gingivitis is usually related to the dematologic disorders that produce cutaneous and mucous membrane blisters. The cicatricial pemphigoid and lichen planus are representative diseases of the dermatologic cases. Patients may be asymptomatic or symptomatic. When symptomatic, their complaints range from a mild burning sentation to an severe pain. The clinical examination must be considered with a thorough history, and routine histologic and immunofluorescence studies. A systemic approach needs to achieve accurate diagnosis and treatment of the gingival desquamative diseases.

• International Journal of Oral Biology
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• 제45권1호
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• pp.25-31
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• 2020

Enamel knot (EK)-a signaling center-refers to a transient morphological structure comprising epithelial tissue. EK is believed to regulate tooth development in early organogenesis without its own cellular alterations, including proliferation and differentiation. EKs show a very simple but conserved structure and share functions with teeth of recently evolved vertebrates, suggesting conserved signaling in certain organs, such as functional teeth, through the course of evolution. In this study, we examined the expression patterns of key EK-specific genes including Dusp26, Fat4, Meis2, Sln, and Zpld1 during mice embryogenesis. Expression patterns of these genes may reveal putative differentiation mechanisms underlying tooth morphogenesis.