• Restorative Dentistry and Endodontics
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• 제21권1호
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• pp.227-241
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• 1996

The effect of collagen dissolution in acid conditioned dentin was morphologically examined by both scanning and transmission electron microscopy. 18 freshly extracted human molars and dentin bonding systems of All Bond 2, Scotchbond Multipurpose, Superbond D-Liner were used in this study. For SEM preparation, each 3 of ~ exposed dentin surfaces were acid conditioned by using various acids within the above three bonding systems respectively. After acid conditioning of the other 3 exposed dentin surfaces as above, they were treated with 1.7% NaOCl for 2 minutes. The remaining 3 dentin surfaces were acid conditioned and treated with 3.3 % NaOCl for 2 minutes. All of the specimens were then fixed in 4 % glutaraldehyde for 12 h at $4^{\circ}C$ and dehydrated in ethanols grades from 50 % to 100 %, then surface changes of the specimens were observed by using SEM. For TEM preparation, exposed dentin surfaces were acid conditioned with the same acid as SEM specimens and treated with 1.7%, 3.3 % NaOCl respectively, then applied with corresponding bonding agents. After the procedures were finished, composite resin were applied on the dentin surfaces and light cured. Small, rectangular sticks with end dimensions of approximately 1 by 1 mm were sectioned and further sample preparative techniques for transmission electron microscopy were performed in accordance with the procedures used for ultrastructural TEM observations of calcified tissues. The results were as follows : 1. In the 1.7 % NaOCl retreated specimens after acid conditioning, the porous dentin surface of intertubular dentin and wide opening of dentinal tubules were appeared. And there were fine irregularities on the intertubular dentin, indicating a clear difference as compared with the acid conditioned specimens. 2. In the 3.3% NaOCl retreated specimens after acid conditioning, the intertubular dentin was further eroded causing a more porous and wider opening of dentinal tubules. Moreover, sharp irregularities on the intertubular dentin were more evident than those of acid conditioned and 1.7% NaOCl retreated specimens. 3. In all of the acid conditioned specimens, the resin-dentin hybrid layer of approximately 3.5mm thickness was formed and the collapsed collagen layer was observed on the uppermost part of hybrid layer in the specimens applied with All Bond 2. The collgen fibrils of intertubular dentin in specimens applied with Scotchbond Multipurpose were running perpendicular to the interface, and electron dense black layer demarcated from the deep unaltered dentin was more evident in the specimen applied with Superbond D-Liner than any other specimens. 4. In the 1.7 % NaOCl retreated specimens after acid conditioning, the resin-dentin hybrid layer of approximately 2.5-3.0mm thickness was formed and the collapsed collagen layer and longitudinally running collagen fibrils as shown in the acid conditioned specimens were observed in the specimens applied with All Bond 2 and Superbond D-Liner. 5. In all of the 3.3% NaOCl retreated specimens after acid conditioning, the evidence of resin-dentin hybrid layer was not identified ; nevertheless, the longitudinally running collagen fibrils remained slightly in the specimens applied with All Bond 2.

• Bulletin of the Korean Chemical Society
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• 제29권8호
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• pp.1505-1509
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• 2008

Comparative molecular simulations were performed to establish molecular interaction and inhibitory effect of flavonoid myricetin on formation of amyloid fibris. For computational comparison, the conformational stability of myricetin with amyloid $\beta$ -peptide (A$\beta$ ) and $\beta$ -amyloid fibrils (fA$\beta$) were traced with multiple molecular dynamics simulations (MD) using the CHARMM program from Monte Carlo docked structures. Simulations showed that the inhibition by myricetin involves binding of the flavonoid to fA$\beta$ rather than A$\beta$ . Even in MD simulations over 5 ns at 300 K, myricetin/fA$\beta$ complex remained stable in compact conformation for multiple trajectories. In contrast, myricetin/A$\beta$ complex mostly turned into the dissociated conformation during the MD simulations at 300 K. These multiple MD simulations provide a theoretical basis for the higher inhibitory effect of myricetin on fibrillogenesis of fA$\beta$ relative to A$\beta$ . Significant binding between myricetin and fA$\beta$ observed from the computational simulations clearly reflects the previous experimental results in which only fA$\beta$ had bound to the myricetin molecules.

• International Journal of Oral Biology
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• 제31권3호
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• pp.93-98
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• 2006

Biosynthetic processing of fibrillar procollagens is essential for producing mature collagen monomers that polymerize into fibrils by a self-assembly process. The metalloproteinase ADAMTS-2 is the major enzyme that processes the N-propeptide of type I procollagen in the skin and also of type II and type III procollagens. Mutations in the ADAMTS-2 gene cause dermatospraxis in animals and Ehlers-Danlos syndrome VIIC in humans, both of which are characterized by the accumulation of type I pN-collagen and the formation of abnormal collagen fibrils in the skin. Despite its importance in procollagen processing, little is known about the regulation of ADAMTS-2 expression. Here, we demonstrate that ADAMTS-2 can be regulated by 1,25-dihydroxyvitamin D3, an inducer of type I procollagen synthesis. This steroid hormone induced ADAMTS-2 mRNA ${\sim}3-fold$ in MG-63 human osteosarcoma cells and MC3T3-E1 murine osteoblastic cells. This induction was dose- and time-dependent in MG-63 cells. In contrast, secreted ADAMTS-2 protein was increased only 1.4-fold with 1,25-dihydroxyvitamin D3. Finally, 1,25-dihydroxyvitamin D3 in the presence of ascorbate increased levels of secreted ADAMTS-2 1.9-fold over ascorbate treatment alone, which did not appreciably change ADAMTS-2 expression. These data indicate that the regulation of ADAMTS-2 is coupled with the synthesis of type I procollagen through 1,25-dihydroxyvitamin D3 signaling and may involve translational or posttranslational control.

• 식물분류학회지
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• 제41권1호
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• pp.35-46
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• 2011

한국산 가지과 12속 22분류군의 종자 특징을 해부현미경과 주사전자현미경을 통하여 관찰하고 자세히 기재하였다. 연구된 분류군의 종자 색깔은 노란색에서 검정색까지 관찰되며, 종자 형태는 신장형에서 원형까지 나타났다. 종자 크기는 길이 0.56-4.29 mm, 폭 0.38-3.20 mm로, Datural metel이 가장 크고 Petunia hybrida가 가장 작았다. 종자의 표면무늬는 세 가지 유형으로 과립형, 과립상-망상형, 망상형이 나타났다. 수층벽의 유형은 파상형과 직선형으로 관찰되었다. 대부분의 분류군은 파상형을 갖고, Datura속, Petunia속, Scopolia속에서는 직선형만 관찰되었으며, Nicandra physalodes는 직선형과 파상형을 모두 갖는다. Solanum속내 일부 분류군에서는 종자의 수층벽 상단부위에 모용처럼 보이는 섬유소가 관찰되었다(S. japonense, S. lyratum, S. lycopersicum). 한국산 가지과에 대한 종자의 형태학적 형질을 속별로 기재하였고, 그 분류학적 유용성에 대해 논의하였다.

• EDISON SW 활용 경진대회 논문집
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• 제4회(2015년)
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• pp.14-23
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• 2015

Alzheimer's disease is one of the most common types of degenerative dementia. As a considerable cause of Alzheimer's disease, neurotoxic plaques composed of 39 to 42 residue-long amyloid beta($A{\beta}$) fibrils have been found in the patient's brain in large quantity. A previous study found that erythrosine B (ER), a red color food dye approved by FDA, inhibits the formation of amyloid beta fibril structures. Here, in an attempt to elucidate the inhibition mechanism, we performed molecular dynamics simulations to demonstrate the conformational change of $A{\beta}40$ induced by 2 ERs in atomistic detail. During the simulation, the ERs bound to the surfaces of both N-terminus and C-terminus regions of $A{\beta}40$ rapidly. The observed stacking of the ERs and the aromatic side chains near the N-terminus region suggests a possible inhibition mechanism in which disturbing the inter-chain stacking of PHEs destabilizes beta-sheet enriched in amyloid beta fibrils. The bound ERs block water molecules and thereby help stabilizing alpha helical structure at the main chain of C-terminus and interrupt the formation of the salt-bridge ASP23-LYS28 at the same time. Our findings can help better understanding of the current and upcoming treatment studies for Alzheimer's disease by suggesting inhibition mechanism of ER on the conformational transition of $A{\beta}40$ at the molecular level.

• 통합자연과학논문집
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• 제5권2호
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• pp.107-119
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• 2012

Polymerization of monomeric amyloid-${\beta}$ peptides ($A{\beta}$) into soluble oligomers and insoluble fibrils is one of the major pathways triggering the pathogenesis of Alzheimer's disease (AD). Using small molecules to prevent the polymerization of $A{\beta}$ peptides can, therefore, be an effective therapeutic strategy for AD. In this study, we investigated the effects of mono- and bi-flavonoids on $A{\beta}42$ toxicity and fibrillogenesis and found that the bi-flavonoid, taiwaniaflavone (TF) effectively and specifically inhibits $A{\beta}$ toxicity and fibrillogenesis. Compared to TF, the mono-flavonoid apigenin (AP) is less effective and less specific. Our data showed that differential effects of the mono- and bi-flavonoids on $A{\beta}$ fibrillogenesis correlate with their varying cytoprotective efficacies. We also found that other bi-flavonoids, namely 2',8"-biapigenin, amentoflavone, and sumaflavone, can also effectively inhibit $A{\beta}$ toxicity and fibrillogenesis, implying that the participation of two mono-flavonoids in a single bi-flavonoid molecule enhanced their activity. Bi-flavonoids, while strongly inhibited $A{\beta}$ fibrillogenesis, accumulated nontoxic $A{\beta}$ oligomeric structures, suggesting that these are off-pathway-oligomers. Moreover, TF abrogated the toxicity of preformed $A{\beta}$ oligomers and fibrils, indicating that TF and other bi-flavonoids may also reduce the toxicity of toxic $A{\beta}$ species. Altogether, our data clearly show that bi-flavonoids, possibly due to the possession of two $A{\beta}$ binders separated by an appropriate size linker, are likely to be promising therapeutics to suppress $A{\beta}$ toxicity.

• Tissue Engineering and Regenerative Medicine
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• 제15권6호
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• pp.711-719
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• 2018

BACKGROUND: Collagen organization within tissues has a critical role in wound regeneration. Collagen fibril diameter, arrangements and maturity between connective tissue growth factor (CTGF) small interfering RNA (siRNA) and mismatch scrambled siRNA-treated wound were compared to evaluate the efficacy of CTGF siRNA as a future implement for scar preventive medicine. METHODS: Nanocomplexes of CTGF small interfering RNA (CTGF siRNA) with cell penetrating peptides (KALA and $MPG^{{\Delta}NLS}$) were formulated and their effects on CTGF downregulation, collagen fibril diameter and arrangement were investigated. Various ratios of CTGF siRNA and peptide complexes were prepared and down-regulation were evaluated by immunoblot analysis. Control and CTGF siRNA modified cells-populated collagen lattices were prepared and rates of contraction measured. Collagen organization in rabbit ear 8 mm biopsy punch wound at 1 day to 8 wks post injury time were investigated by transmission electron microscopy and histology was investigated with Olympus System and TS-Auto software. CONCLUSION: CTGF expression was down-regulated to 40% of control by CTGF siRNA/KALA (1:24) complexes (p<0.01) and collagen lattice contraction was inhibited. However, down-regulated of CTGF by CTGF $siRNA/MPG^{{\Delta}NLS}$ complexes was not statistically significant. CTGF KALA-treated wound appeared with well formed-basket weave pattern of collagen fibrils with mean diameter of $128{\pm}22nm$ (n = 821). Mismatch siRNA/KALA-treated wound showed a high frequency of parallel small diameter fibrils (mean $90{\pm}20nm$, n = 563). CONCLUSION: Controlling over-expression of CTGF by peptide-mediated siRNA delivery could improve the collagen orientation and tissue remodeling in full thickness rabbit ear wound.

• 대한기관식도과학회지
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• 제2권1호
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• pp.135-139
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• 1996

Laryngeal amyloidosis is a rare benign disease. It is characterized by extracellular deposition of homogeneous and eosinophilic protein material in the form of fibrils. Diagnosis of this disease is made by histologic examination of involved tissue. It is ususlly primary or localized but rarely associated with a systemic or generalized disease. We present a case of primary laryngeal amyloidosis that was treated with KTP 532 laser vaporization.

• 대한치과교정학회지
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• 제17권2호
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• pp.223-248
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• 1987

The early tissue reactions in the periodontal tissues of the tension zones following the application of force (30gm) to the maxillary first molar teeth of the albino rats were studied by the light microscopy and electron microscopy The increase of periodontal fibroblasts was evident, particularly in 1 day survival period. Osteoblast differentiation and new bone formation on the alveolar bone surface were occurred from 1 day survival period. Mononuclear phagocytes occurred consistently and in relatively high number adjacent to and at some distance from blood vessel Extensive breakdown of collagen fibers was observed. The increase of the phagocytosis of collagen by the active fibroblasts was evident Also, collagen fibrils were sparse or lost near the macrophage.

• 펄프종이기술
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• 제30권4호
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• pp.49-58
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• 1998

The SPM could image the most detailed microstructure of a sample in a wet and dry state by measuring the interaction between the atoms on the sample surface and the extremely sharp probe tip. The refined fibre exhibited large wrinkles formed by fibrillar bundles, the disintegrated fibres extensively showed “scale-like features”. By using the Non-Contact Atomic Force Microscopy (NC-AFM) and Contact Atomic Force Microscopy (C-AFM) including Phase Detection Microscopy (PDM) and Force Modulation Microscopy (FMM), it was possible to investigate surface topography, surface roughness and mechanical property (hardness or visco-elasticity) of fibre surface in detail. The PDM and FMM images showed that the disintegrated only fibre displayed uniform mechanical properties, whereas the refined one did not. The surface roughness of pulp fibres was higher in refined fibres than in disintegrated fibres due to the presence of external fibrils. These SPM images would be used to provide visual evidence of morphological change of a single fibre created during mechanical treatments such as refining, drying, calendering and so on.