• Radiation Oncology Journal
• /
• v.26 no.4
• /
• pp.257-262
• /
• 2008

Purpose: Oral mucositis induced by radiotherapy to the head and neck area, is a common acute complication and is considered as the most severe symptom for cancer patients in the early stages of treatment. This study was proposed to establish the oral mucositis mouse model induced by a single dose of radiation for the facility of testing therapeutic candidates which can be used for the oral mucositis treatments. Materials and Methods: Fifty-five BALB/c mice were divided into four groups: control, 16 Gy, 18 Gy, and 20 Gy. Oral mucositis was induced by a single dose of radiation to the head and neck using 6 MV x-Ray from linear accelerator. After irradiation, body weight and physical abnormalities were checked daily. Tongue tissues from all groups were taken on days 1, 2, 3, 5, 7, 9, and 14, respectively and H&E staining was conducted to examine morphological changes. Results: Body weight dramatically decreased after day 5 in all irradiated mice. In the 16 Gy treatment group, body weight was recovered on day 14. The histology data showed that the thickness of the epithelial cell layer was decreased by the accumulated time after radiation treatment, up to day 9. Severe ulceration was revealed on day 9. Conclusion: A single dose of 16 Gy is sufficient dose to induce oral mucositis in Balb/C mice. Significant changes were observed in the Balb/C mice on days 7 and 9 after radiation. It is suggested that this mouse model might be a useful standard tool for studying oral mucositis induced by radiation.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.29 no.6
• /
• pp.421-429
• /
• 2003

Purpose : Neoadjuvant chemotherapy is commonly used to treat cancer patients as adjunct treatment, but if the microvascular tissue transfer is performed simulataneously with cancer resection surgery, the induction chemotherapy might affect the survival rate of vascularized free flap. Our study will focus on the effect of induction chemotherapy on the free flaps which were made on white rat abdomen after injection of 5-FU. Materials and Methods: The experimental rat groups were divided into three groups (total 24 rats) as a normal control group, 24 hrs group after 5-FU injection, 3 days group after 5-FU injection. Inferior abdominal island flaps of 8 Sprague Dawley rats on each group were made and immediately were induced into an ischemic state by clamping the supplying inferior epigastric artery and vein with microvascular clamp for a hour to induce a similiar free flap circumstance, then the inferior abdominal skin flaps were reperfused by releasing the clamps. The flaps on abdomen were repositioned and sutured. The experimental data for flap survival rate was collected by digital photo taking, analysed by computer image program to compare with the flap luminosity. The rats were sacrificed at 3 days, 5 days, 7 days after flap preparation and specimens of the flap were taken and stained with H-E staining. The microscopic finding was made under magnification of 200 and 400. Results: 1. Gross findings on each groups showed the healing condition was good as following sequences; normal, 24 hrs group after chemotherapy, 3 days group after chemotherpy. 2. The values of flap luminosity for evaluation of flap survival rate also showed the same sequences as gross findings of healing state. 3. The microscopic findings of epidermis necrosis, inflammation state, dermis fibrosis, vessel change, fatty tissue layer thinning were compared with each group. The 3 days group after chemotherapy showed remarkably poor healing condition compared to other groups. Conclusion: Chemotherapy agents affected the healing process of free flap, but healing condition was recovered spontaneously as post-injection periods passed out. In opposite to our expectation, 3 days group showed the bad flap condition in comparing with 24 hours group which was considered as immatured body circulation state of chemotherapy agent. It showed that 3 weeks in human being after chemotherapy was not proper as timing of microvascular tissue transfer if 3 days group in rat was considered as same healing period of 3 weeks in human being. More delayed healing timing than 3 weeks might be required in clinical application of free tissue transfer.

• Restorative Dentistry and Endodontics
• /
• v.32 no.2
• /
• pp.95-101
• /
• 2007

This study was performed to verify the possibility of MTA and calcium sulfate as a pulp capping agent through comparing the dental pulp response in dogs after capping with MTA, calcium sulfate, and calcium hydroxide. 24 teeth of 2 dogs, 8 month old, were used in this study. Under general anesthesia, cervical cavities were prepared and pulp was exposed with sterilized #2 round bur in a high speed handpiece. MTA calcium hydroxide, and calcium sulfate were applied on the exposed pulp. Then the coronal openin,fs were sealed with IRM and light-cured composite. Two months after treatment, the animals were sacrificed. The extracted teeth were fixed in 10% neutral-buffered formalin solution and were decalcified in formic acid-sodium citrate. They were prepared for histological examination in the usual manner. The sections were stained with haematoxylin and eosin. In MTA group, a hard tissue bridges formation and newly formed odontoblasts layer was observed. There was no sign of pulp inflammatory reaction in pulp tissue. In calcium hydroxide group, there was no odontoblast layer below the dentin bridge. In pulpal tissue, chronic inflammatory reaction with variable intensity and extension occurred in all samples. In calcium sulfate group, newly formed odontoblast layer was observed below the bridge. Mild chronic inflammation with a few neutrophil infiltrations was observed on pulp tissue. These results suggest that MTA is more biocompatible on pulp tissue than calcium hydroxide or calcium sulfate.

• Korean journal of applied entomology
• /
• v.48 no.3
• /
• pp.385-392
• /
• 2009

Two entomopathogenic bacteria, Xenorhabdus nematophila and Photorhabdus temperata subsp. temperata, are known to be potent against the diamondback moth, Plutella xylostella, when the bacteria are injected into the hemocoel. This study investigated any pathogenic effect of their culture broth on P. xylostella by oral administration. Only culture broth of both bacterial species did not give enough pathogenic effects by the oral administration. However, when the culture broth was orally treated together with Bacillus thuringiensis (Bt), both cell-free culture broth significantly enhanced Bt pathogenicity against the 3rd instar larvae of P. xylostella. The culture broth was then fractionated into hexane, ethyl acetate, and aqueous extracts. Most synergistic effect on Bt pathogenicity was found in ethyl acetate extracts of both bacterial species. Thin layer chromatography of these extracts clearly showed that ethyl acetate extracts of both bacterial culture broths possessed metabolites that were different to those of hexane and aqueous extracts. These results suggest that the both entomopathogenic bacteria produce and secrete different factors to give significant synergistic effect on Bt pathogenicity.

• Journal of Periodontal and Implant Science
• /
• v.32 no.1
• /
• pp.129-142
• /
• 2002

Epithelial-mesenchymal interaction plays a important role in cell growth and differentiation. This interaction is already well known to have an importance during the organ development as well as cell growth and differentiation. However, in vitro experimental model is not well developed to reproduce in vivo cellular microenvironment which provide a epithelial-mesenchymal interaction. Because conventional monolayer culture lacks epithelial-mensenchymal interaction, cultivated cells have an morphologic, biochemical, and functional characteristics differ from in vivo tissue. Moreover, it's condition is not able to induce cellular differention due to submerged culture condition. Therefore, the aims of this study were to develop and evaualte the in vitro experimental model that maintains epithelial-mesenchymal interaction by organotypic raft culture, and to characterize biologic properties of three-dimensionally reconstituted oral keratinocytes by histological and immunohistochemical analysis. The results were as follow; 1. Gingival keratinocytes reconstituted by three-dimensional organotypic culture revealed similar morphologic characteristics to biopsied patient specimen showing stratification, hyperkeratinosis, matutation of epithelial architecture. 2. Connective tissue structure was matured, and there is no difference during stratification period of epithelial 3-dimensional culture. 3. The longer of air-exposure culture on three-dimensionally reconstituted cells, the more epithelial maturation, increased epithelial thickness and surface keratinization 4. In reconstitued mucosa, the whole epidermis was positively stained by anti-involucrin antibody, and there is no difference according to air-exposured culture period. 5. The Hsp was expressed in the epithelial layer of three-dimensionally cultured cells, especially basal layer of epidermis. The change of Hsp expression was not significant by culture stratification. 6. Connexin 43, marker of cell-cell communication was revealed mild immunodeposition in reconstitued epithelium, and there is no significant expression change during stratification. These results suggest that three-dimensional oragnotypic co-culture of normal gingival keratinocytes with dermal equivalent consisting type I collagen and gingival fibroblasts results in similar morphologic and immunohistochemical characteristics to in vivo patient specimens. And this culture system seems to provide adequate micro-environment for in vitro tissue reconstitution. Therefore, further study will be focused to study of in vitro gingivitis model, development of novel perioodntal disease therapeutics and epithelial-mensenchymal interaction.

• Laboraroty Animal Research
• /
• v.34 no.4
• /
• pp.176-184
• /
• 2018

In this study, we observed chronological changes in the immunoreactivity and expression level of myelin basic protein (MBP), one of the most abundant proteins in the central nervous system, in the hippocampus of Zucker diabetic fatty (ZDF) rats and their control littermates (Zucker lean control; ZLC). In the ZLC group, body weight steadily increased with age; the body weight of the ZDF group, however, peaked at 30 weeks of age, and subsequently decreased. Based on the changes of body weight, animals were divided into the following six groups: early (12-week), middle (30-week), and chronic (52-week) diabetic groups and their controls. MBP immunoreactivity was found in the alveus, strata pyramidale, and lacunosum-moleculare of the CA1 region, strata pyramidale and radiatum of the CA3 region, and subgranular zone, polymorphic layer, and molecular layer of the dentate gyrus. MBP immunoreactivity was lowest in the hippocampus of 12-week-old rats in the ZLC group, and highest in 12-week-old rats in the ZDF group. Diabetes increased MBP levels in the 12-week-old group, while MBP immunoreactivity decreased in the 30-week-old group. In the 52-week-old ZLC and ZDF groups, MBP immunoreactivity was detected in the hippocampus, similar to the 30-week-old ZDF group. Western blot results corroborated with immunohistochemical results. These results suggested that changes in the immunoreactivity and expression of MBP in the hippocampus might be a compensatory response to aging, while the sustained levels of MBP in diabetic animals could be attributed to a loss of compensatory responses in oligodendrocytes.

• The korean journal of orthodontics
• /
• v.44 no.5
• /
• pp.246-253
• /
• 2014

Objective: To evaluate the bioactivity, and the biomechanical and bone-regenerative properties of Ti6Al4V miniscrews subjected to anodization, cyclic precalcification, and heat treatment (APH treatment) and their potential clinical use. Methods: The surfaces of Ti6Al4V alloys were modified by APH treatment. Bioactivity was assessed after immersion in simulated body fluid for 3 days. The hydrophilicity and the roughness of APH-treated surfaces were compared with those of untreated (UT) and anodized and heat-treated (AH) samples. For in vivo tests, 32 miniscrews (16 UT and 16 APH) were inserted into 16 Wistar rats, one UT and one APH-treated miniscrew in either tibia. The miniscrews were extracted after 3 and 6 weeks and their osseointegration (n = 8 for each time point and group) was investigated by surface and histological analyses and removal torque measurements. Results: APH treatment formed a dense surface array of nanotubular TiO2 layer covered with a compact apatite-like film. APH-treated samples showed better bioactivity and biocompatibility compared with UT and AH samples. In vivo, APH-treated miniscrews showed higher removal torque and bone-to-implant contact than did UT miniscrews, after both 3 and 6 weeks (p < 0.05). Also, early deposition of densely mineralized bone around APH-treated miniscrews was observed, implying good bonding to the treated surface. Conclusions: APH treatment enhanced the bioactivity, and the biomechanical and bone regenerative properties of the Ti6Al4V alloy miniscrews. The enhanced initial stability afforded should be valuable in orthodontic applications.

• Journal of Ginseng Research
• /
• v.44 no.6
• /
• pp.823-832
• /
• 2020

Background: The formation of a nanotube layer on a titanium nanotube (N-Ti) plate facilitates an active reaction between bone cells and the material surface via efficient delivery of the surface materials of the dental implant into the tissues. Studies have reported that Korean Red Ginseng extracts (KRGEs) are involved in a variety of pharmacological activities: we investigated whether implantation with a KRGE-loaded N-Ti miniimplant affects osteogenesis and osseointegration. Methods: KRGE-loaded nanotubes were constructed by fabrication on pure Ti via anodization, and MC3T3-E1 cells were cultured on the N-Ti. N-Ti implants were subsequently placed on a rat's edentulous mandibular site. New bone formation and bone mineral density were measured to analyze osteogenesis and osseointegration. Results: KRGE-loaded N-Ti significantly increased the proliferation and differentiation of MC3T3-E1 cells compared with cells on pure Ti without any KRGE loading. After 1-4 weeks, the periimplant tissue in the edentulous mandibular of the healed rat showed a remarkable increase in new bone formation and bone mineral density. In addition, high levels of the bone morphogenesis protein-2 and bone morphogenesis protein-7, besides collagen, were expressed in the periimplant tissues. Conclusion: Our findings suggest that KRGE-induced osteogenesis and osseointegration around the miniimplant may facilitate the clinical application of dental implants.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.16 no.4
• /
• pp.397-418
• /
• 1994

Microvascular surgery has been widely used in the clinical field of replantation and reconstructive surgery. Since the last 20 years, microsurgical techniques and instruments have been rapidly developed and the success rate is remarkably increased. But thrombotic occlusion of vessels remains the major reason for clinical failure. The change of vessel wall is the most important factor in thrombus formation. If we can reduce the traumatic changes in the vessel walls during surgery, the success rate can be markedly increased. For this study, femoral arteries and veins of 36 Sprague-Dawley rats with average weights of 300gm were used. The author observed the histological changes and healing process in the anastomostic site after 1 hour, 24 hours, 1, 2, 3 and 4 weeks under light microscopy and scanning electron microscopy. The results were as follows : 1. The patency rate was 100% in femoral arteries and 85% in femoral vein. 2. At the early stages after microvascular anastomosis, the loss of endothelial cell in the vessel walls was observed in the wide area including anastomotic site. In scanning electron microscopic finding the anastomotic site was covered with much fibrin, many red blood cells and some platelets. 3. At 1st week, new endothelial cells were formed toward anastomotic site and at 3rd week, the anastomotic site was completely covered by new endothelial cells. At 4th week, the complete endothelialization over the threads was observed. 4. The media extended from the anastomotic site toward the end of the specimen. At later stages, the extent of media necrosis was markedly decreased. But the media necrosis of anastomotic site was not regenerated till 4th week. 5. Intimal hyperplasia appeared at 1st week and increased till 4th week. The layer consisted of endothelialization the most luminal layers and smooth muscle in the deeper layers. But in veins, the response was less pronounced than in arteries. 6. Foreign body granuloma remained during 4 weeks and aneurysm was observed at 3rd week in artery. In aneurismal wall, media necrosis, loss of elastic lamina and intimal hyperplasia were seen.

• International Journal of Oral Biology
• /
• v.33 no.2
• /
• pp.59-64
• /
• 2008

This study was designed to investigate the changes in the properties of the neuronal setm cells or progenitor cells associated with age-related decline in neurogenesis of the hippocampal dentate gyrus (DG). Active whole cells cycle marker Ki67 (a marker of whole cell cycle)-positive and S phase marker bromodeoxyuridine (BrdU)-positive. Neural stem cells gradually were reduced in the hippocampal subgranular zone (SGZ) in an age-dependant manner after birth (from P1 month to P1 year). The ratio of BrdUpositivecells/Ki67-positive cells was gradually enhanced in an age-dependent manner. The ratio of Ki67-positive cells/accu-mulating BrdU-positive cells at 3 hrs after BrdU injection was injected once a day for consecutive 5 days gradually decreased during ageing. TUNEL- and caspase 3 (apoptotic terminal caspase)-positive cells gradually decreased in the dentate SGZ during ageing and immunohistochemical findings of glial fibrillary acid protein (GFAP) were not changed during ageing. NeuN, a marker of mature neural cells, and BrdU-double positive cells gradually decreased in an age-dependent manner but differentiating ratio and survival rate of cells were not changed at 4 wks after BrdU injection once a day for consecutive 5 days. The number of BrdU-positive cells migrated from the hippocampal SGZ into granular layer and its migration speed was gradually declined during ageing. These results suggest that the adult neurogenesis in the mouse hippocampal DG gradually decrease through reducing proliferation of neural stem cells accompanying with cells cycle change and reduced cells migration rather than changes of differentiation.