• Applied Microscopy
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• v.32 no.1
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• pp.57-66
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• 2002

The structures of sucker of two Cobiidae; Common freshwater goby and Triden goby were observed by light and electron microscopy. Scanning electron microscopy revealed the characteristic narrow ridges and grooves on the apical portion of sucker of Common freshwater goby, and hexagonal structures similar to a honeycomb representing the intercellular junctional area on the middle and basal portions. Some ridges were present on the epithelial surface on the middle and basal portions. The openings of several mucus-secreting cells were present between main epithelial cells. Light and transmission electron microscopy revealed the core of the fin; soft rays with a surrounding dense collagen fiber layer. Some loosely arranged fibers (collagen fiber) radiated toward the surface epithelium. The surface epithelium was cuboidal or columnar in shape. Scanning electron microscopy revealed the coiled irregular ridges and grooves, which was less developed and had sparser distribution than in Common freshwater goby, on the apical portion of sucker of Triden goby. The middle and basal portions had honeycomb structures as in Common freshwater goby. Fewer mucoussecreting cells were present. Light and transmission electron microscopy showed the core of soft rays, dense collagen fiber layer, however, the radiating fibers observed in the Common freshwater goby was rarely present. The sucker was thinner because the epithelium is squamous or polygonal in shape and rare presence of the radiating fibers.

• Restorative Dentistry and Endodontics
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• v.23 no.1
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• pp.141-161
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• 1998

The depth and patterns of demineralization according to the difference in concentration and application time of phosphoric acid were observed through the transmission electron microscope, and shear bond strengths to the acid -conditioned dentin were then measured and compared with the TEM results. To investigate the influence of polymer addition into the phosphoric acid and the effect of difference in concentration and application time of the acid, the specimens were randomly divided into 9 groups. Among the specimens, the exposed dentin surfaces were acid-conditioned with 10% polymer-thickened phosphoric acid(All Bond 2, Bisco, U.S.A.) and aqueous 10%, 20%, 30%, 40% phosphoric acid for 20 seconds, The rest of the specimens were acid-conditioned with 10% phosphoric acid for 15s, 30s, 60s, 120s respectively. The specimens were immersed in 4% glutaraldehyde in 0.1M sodium cacodylate buffer and postfixed with 1 % osmium tetroxide without decalcification and then observed under a JEOL Transmission Electron Microscope(JEM 1200 EX II, Japan). After the specimens were acid-conditioned as the above, primer and adhesive resin were applied to blot-dried dentin and shear bond strengths were then measured and analysed. The results were as follows : 1. The intertubular demineralization depth of 4.0-$5.0{\mu}m$ in 10% polymer-thickened phosphoric acid gels was similar or slightly deeper than that of 4.0-$4.5{\mu}m$ in aqueous 10% phosphoric acid solution. 2. The intertubular demineralization depth of aqueous 20%, 30% and 40% phosphoric acid solution was 6.5-$7.0{\mu}m$, 6.5-$7.5{\mu}m$ and 9.0-$15.0{\mu}m$ respectively. It showed that the depth of dentin demineralization is partly related to the concentration of phosphoric acid solution. 3. The intertubular demineralization depth of aqueous 10% phosphoric acid solution in application time for 15s, 30s, 60s and 120s was 2.5-$3.0{\mu}m$, 4.0-$6.0{\mu}m$, 6.5-$7.0{\mu}m$ and 8.5-$14.0{\mu}m$ respectively. It showed that the depth of dentin demineralization is directly related to the application time of phosphoric acid solution. 4. The partially demineralized dentin layer between demineralized collagen layer and unaffected dentin was showed to a width of 0.5-$1.0{\mu}m$ in lower concentration groups treated with aqueous 10% phosphoric acid for 20s, 60s, 120s and 20% phosphoric acid for 20s. 5. The demineralization effect at the border of intertubular-peritubular junction was less evident than that in the peritubular and intertubular dentin. The collagen fibers in the intertubular dentin had a random orientation, whereas those that lined the tubules were circumferentially aligned. The cross-linkage of dentinal collagen in demineralized collagen layer was clearly seen. 6. A statistically significant difference of bond strengths according to the difference in phosphoric acid concentration did not exist among the groups treated with 10%, 20%, 30% and 40% acid solution (P>0.05). However, bond strengths to the treated dentin with 10% phosphoric acid solution for 30s were significantly higher than that for 120s (P<0.05).

• Maxillofacial Plastic and Reconstructive Surgery
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• v.15 no.3
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• pp.157-170
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• 1993

To prove the effct of semi-rigid fixation which utilize wire and rigid fixation which utilizes miniplate toward cranio-facial growth and development of growing children for teenagers, 28 rabbits-6 weeks, about 1.5kg-were experimented. They were classified three groups the semi-rigid group was 12 rabbits which were fixed with 26 gauge stainless steel wire to cross a fronto-nasal suture, the rigid group was the other 12 rabbits which were fixed with miniplate and screw, the control group was 4 rabbits which were get rid of only periosteum. The sample of fronto-nasal of rabbits which were sacrified after 2 weeks, 4 weeks, 8 weeks, and 12 weeks of the operation were investigated and made a comparative study with the light microscops. 1. At the control group, the central part of bony suture was connected with colagen bundle, the osteoblastic layer was investigated at the bony ending, new bone which covered the inside and outside faces of the bone suture was formed between periosteum. 2. Two weeks later from the experiment, ran slightly irregularly the collagen bundle which connects both bony endings of the rigid group. 3. Four weeks later from the experiment, collagen bundle of bone surface were arranged parally a little and comparing to the semi-rigid group, newly formed woven bone of surface of the adjacent bone was made obviously a little. 4. Eight weeks later from the experiment, collagen bundle which is located between both bony ending become close. Both the semi-rigid group and the rigid group showed significant formation of new bone at the periosteum and the bone surface. 12 weeks later from the experiment, both the semi-rigid group and the rigid group showed the regular running in the collagen bundle and smooth, dense periosteum. Then they assumed a similar aspect of the control group. I think that it does not give the influence to the cranio-facial growth of children or teenager to utilize a rigid fixation for a short period. Because as the time goes on, the surface of the bone suture was recovered and adjacent bone surface of the miniplate fixation showed compensatory growth, although both the semi-rigid group which utilized wire and rigid group which utilized a miniplate brought about the change of the area of the bone suture at the early period.

• Imaging Science in Dentistry
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• v.32 no.1
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• pp.11-18
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• 2002

Purpose: To evaluate cultured human artificial skin as an experimental model for studying radiation effects in vitro. Materials and Methods: The skin was constructed by culturing keratinocytes over collagen lattice which made by culturing fibroblasts. Two groups were irradiated to gamma rays at single dose of 25 Gy with or without 3.5% of DMSO. Ultrastructures were investigated by electron microscopy after irradiation. The number of epidermal layers and expression of cytokeratin (CK) 14 & 10 were also seem by light microscopy. Results: At 2 days after irradiation in experimental group without DMSO, necrotic cells were rarely found in the spinosal layer and undercornified cells were visible in the homey layer. Similar findings were also found in experimental group with DMSO but in mild form. The number of epidermal layers in experimental group without DMSO were significantly fewer than other group. CK 14 expressed in all the layer excluding homey layer but CK 10 expressed over 3∼4 basal layers. Such patterns of CK expression were similar to all groups. It is suggested that structures of the keratinocytes and epidermal formation could be disturbed by irradiation in artificial skin and that DMSO can protect these damages. Conclusion : Therefore this work could be used as an organotypic experimental model in vitro using human cells for studying radiation effect in skin. Furthermore structural findings provided in this study could be used as useful basic data in further study using this model.

• Restorative Dentistry and Endodontics
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• v.22 no.1
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• pp.470-478
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• 1997

The purpose of this study was to investigate the effects of moistening mechods of dentin on the morphologic states of hybrid layers and on the interfacial bond strength between dentin and composite. Specimens were divided into 6 groups based on the surface moistening methods and materials used. After the dentin surface was conditioned with 10 % phoporic acid and irrigated: 1. The dentin surface was dried. Then bonding agent and composite were applied. 2. The dentin surface was blot-dryed. Then primer, bonding atent and composite were applied. 3. The dentin surface was dryed first. Within 20 seconds, the surface was rewetted, then primer, bonding agent and composite were applied. 4. The dentin surface was dryed. Then primer, bonding agnent and composite were applied. 5. The dentin surface was dryed first. Atter 24hrs, the surface was rewetted, and then primer, bonding agent and composite were applied. 6. The surface was conditioned with NaOCl for 5min. Then primer, bonding agent and composite were applied. To reveal the hybrid layer, scanning electron microscopy was used after the samples were ion beam etched. The shear bond strength of each group was tom pared by ANOVA. In groups 2, 3 and 4, the hybrid layer was clearly visible, but the width was more limited in group 4. In group 1 and 5, the hybrid layer was not found, and a gap was formed between dentin and composite. In group 6, the hybrid layer was not found, but the interface between the dentin and composite was intimate. The shear bond strength of each group was as follows: Group 1 : 4MPa, Group 2 : 14MPa, Group 3 : 12MPa, Group 4 : 14MPa, Group 5 : 5MPa, Group 6 : 9MPa.

• Restorative Dentistry and Endodontics
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• v.25 no.2
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• pp.180-192
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• 2000

One bottle system was recently developed in order to simplify the clinical skills and save chair time after continuous improvements on dentin bonding agents. There has been many studies to measure the bond strength of one bottle systems but no actual work has been done on micromorphologic study of resin-dentin interdiffusion zone after one bottle system application. To evaluate the bonding patterns of various commercially available one bottle systems to dentin, observation of resin-dentin interdiffusion zone under TEM was performed. Caries-free human third molars within one month of extractions were chosen for the experiments. The molars were sectioned 1mm above the cementoenamel junction and got rid of the root portions. Crown portions of the teeth were sectioned parallel to occlusal surface so that dentin discs of 1mm in thickness were remained. 7 one bottle systems and 1 two bottle system were applied according to manufacturer's instructions and followings were the results. 1. In every experimental groups, cross bandings of collagen fiber were distinguishable and tight bon dings between the bonding agents and dentin were observed. 2. Hybrid layer was clearly observed in ONE-STEP$^{(R)}$, Prime & Bond$^{(R)}$ 2.1, Syntac$^{(R)}$ SC, MAC-BOND II groups but it was not clear in Single Bond, D-Liner Dual PLUS, ONE COAT BOND groups. 3. Electron-density of hybrid layer was uniform in pattern in MAC-BOND II, Prime & Bond$^{(R)}$ 2.1 groups but not so uniform in ONE-STEP$^{(R)}$ group. 4. Electron-dense amorphous phase in most superior layer of the resin-dentin interdiffusion zone was characteristically observed in Single Bond, Syntac$^{(R)}$ SC, ONE COAT BOND groups. It can be concluded that bondings between the dentin bonding agents and dentin can be various in pattern according to their chemical compositions and the condition during applications.

• Journal of Periodontal and Implant Science
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• v.25 no.1
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• pp.76-88
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• 1995

The purpose of this was to evaluate the in vitro effects of different application modes of tetracycline HCI on dentin root surfaces. The study group was comprised of 30 teeth with advanced periodontal disease extracted before the start of periodontal therapy. The diseased root surface was vigorously root planed to expose dentin. The teeth were sectioned and cotton pellets. soaked in a saturated solution of tetracycline HCI, were either "placed" or "burnished" on the prepared root surface for 3, 5 min. respectively. Control surfaces were similarly treated with root planing only. Following the various treatments, teeth were fixed. dehydrated, critical point dried, and coated for scanning electron microscopic(SEM) evaluation. The surfaces of tetracycline HCI treated specimens considerably differed from specimens treated with root planing only. Results demonstrated that root-planed, no-tetracycline HCI specimens had amorphous, irregular surface which corresponded to a smear layer. Tetracycline HCI specimens exhibited collagen fibers and dentinal tubules exposed by the removal of the smear layer. Although some differences were seen in surface structures among some specimens. "burnished" application causes more extensive change than "placed" application, and application time of the tetracycline HCl did not seem to have any major impact on the surface morphology.

• International Journal of Oral Biology
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• v.49 no.1
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• pp.18-25
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• 2024

Despite advancements in therapeutic approaches, radiotherapy and cisplatin-based chemotherapy remain primary noninvasive treatments for patients with oral squamous cell carcinoma (OSCC). Moreover, the 5-year survival rate for patients with OSCC has remained almost unchanged for several decades, and many side effects of chemotherapy still exist. In this study, three-dimensional (3D) models of OSCC were established using fibroblasts, and the efficacy of various biological inhibitors was evaluated. A culture of epithelial cells with two types of fibroblasts (hTERT-hNOFs and cancer-associated fibroblasts) within a type I collagen matrix resulted in the formation of a continuous layer of tightly packed cells compared to models without fibroblasts. Furthermore, the effects of biological chemicals, including Y27632, latrunculin A, and verteporfin, on these models were investigated. The stratified formation of the epithelial layer and invasion in OSCC 3D-culture models were effectively inhibited by verteporfin, whereas invasion was weakly inhibited by Y27632 and latrunculin. Collectively, the developed OSCC 3D-culture models established with fibroblasts demonstrated the potential for drug screening, with verteporfin showing promising efficacy.

• The Korean Journal of Quaternary Research
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• v.17 no.2
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• pp.145-148
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• 2003

The Kunang cave paleolithic site is located at Tanyang [$N37^{\circ}2'$, $128^{\circ}21'E$], Chungbuk Province, which is in the Central part of the Korean peninsula. The cave is developed at 312 amsl in a karstic mountainous area. The South Han River flows across this region and other caves can also be found near the river. The site was discovered in 1986 and excavated 3 times by the Chungbuk National University Museum until now. The cave was wellpreserved from modem human activities until the first discovery. The full length of the cave is estimated to be ca. 140 m. However, a spacious part up to 11 m from the entrance has been excavated. Eight lithological units are divided over the vertical profile at a depth of 5 m. Each unit is deposited in ascending order as follow: mud layer (Unit 9), lower complex (Unit 8) which is composed of angular blocks and fragments with a muddy matrix, lower travertine layer (Unit 7； flowstone), middle complex (Unit 6; cultural layer) which is composed of fragments with a muddy matrix, middle travertine layer (Unit 5； flowstone), yellowish muddy layer (Unit 4), upper complex (Unit 3； cultural layer) which has a similar composition to Unit 8. the upper travertine layer (Unit 2； flowstone), and finally surface soil layer (Unit 1). The most abundant vestiges in the cultural layers are the animal bones. They are small fractured pieces and mostly less than 3 cm in length. About 3,800 bone pieces from 25 animal species have been collected so far, 90 percent of them belonging to young deers. Previous archaeological study of these bone pieces shows thatprehistoric people occupied the cavenot for permanent dwelling but for temporary shelter during their seasonal hunting activity. More extensive studies of these bones together with pollen analysis are in progress to reconstruct the paleoenvironment of this cave. Only a single date (12,500 BP) obtained from a U-Th measurement of the upper travertine layer was previously available. In spite of the importance of the cave stratigraphy, there was no detail chronological investigation to establish the depositional process of the cultural layers and to understand the periodic structure of the cave strata, alternating travertine floor and complex layers. We have measured five 14C age dating (38900+/-1000, 36400+/-900, 40600+/-1600, more than 51000 and 52000 14C BP) using Seoul National University 14C AMS facility, conducted systematic process of the collagen extraction from bone fragments samples. From the result, we estimate that sedimentation rate of the cave earth is constant, and that the travertine layers, Unit 2 and Unit 3, was formed during MIS 5a(ca. 80 kBP) and MIS 5c (ca. 100 kBP) respectively. The Kunang Cave site is located at Yochonli of the region of Danyang in the mid-eastern part of Korea. This region is compased of limestones in which many caves were found and the Nam-han river flows meanderingly. The excavations were carried out three times in 1986, 1988, and 1998.

• Korean Journal of Ichthyology
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• v.28 no.1
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• pp.19-27
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• 2016

The RLG (relative length of gut) is 1.52 (n=12) in the sablefish, Anoplopoma fimbria. The digestive tract has five or six pyloric caeca in the posterior region of stomach. Morphology of mucosal fold is unbranched type in the esophagus and stomach, but branched type in the intestine. The histological structure of digestive tract can be divided into mucosal layer, submucosal layer, muscular layer and serous membrane in the cross section. In the esophagus, mucosal epithelial layer is a simple, and consists of ciliated columnar epithelia and mucous cells. In the stomach, gastric gland of mucosal epithelial layer is a tubular, and is composed of chief cell, parietal cell and mucin secreting cell, which is columnar and contained secretory granules of red and blue colors in the AB-PAS (pH 2.5) reaction. In the intestine, mucosal epithelial layer is a simple, and consists of ciliated columnar epithelia and goblet cells. The submucosal layer is composed mainly of collagen fibers, and well developed in the esophagus. And the muscular layer of digestive tract is divided into longitudinal and circular muscle layer, and well developed in the stomach. The liver is composed of numerous lobular structure and bile canaliculi. Stainability of hepatocyte cytoplasm was eosinophilic, and nucleus and nucleolus showed basophilic in the H-E stain. The pancreatic tissue was scattered in the fatty tissue near the digestive tract, and acinar gland consisting of numerous exocrine cells. And cytoplasmic stainability of exocrine cell was basophilic, and contained numerous zymogen granules of eosinophilic in the H-E stain.