• Journal of Microbiology and Biotechnology
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• 제15권6호
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• pp.1258-1266
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• 2005

The present study was carried out in order to assess the protective effects of calycosin-7-O-$\beta$-D-glucopyranoside, isolated from Astragali radix (AR), on hyaluronidase (HAase) and the recombinant human interleukin-$1\beta$ (IL-$1\beta$)-induced matrix degradation in human articular cartilage and chondrocytes. We isolated the active component from the n-butanol soluble fraction of AR (ARBu) as the HAase inhibitor and structurally identified as calycosin-7-O-$\beta$-D-glucopyranoside by LC-MS, IR, ${1}^H$ NMR, and ${13}^C$ NMR analyses. The $IC_{50}$ of this component on HAase was found to be 3.7 mg/ml by in vitro agarose plate assay. The protective effect of ARBu on the matrix gene expression of immortalized chondrocyte cell line C28/I2 treated with HAase was investigated using a reverse transcription polymerase chain reaction (RT-PCR), and its effect on HAase and IL-$1\beta$-induced matrix degradation in human articular cartilage was determined by a staining method and calculating the amount of degraded glycosaminoglycan (GAG) from the cultured media. Pretreatment with calycosin-7-O-$\beta$-D-glucopyranoside effectively protected human chondrocytes and articular cartilage from matrix degradation. Therefore, calycosin-7-O-$\beta$-D-glucopyranoside from AR appears to be a potential natural ant-inflammatory or antii-osteoarthritis agent and can be effectively used to protect from proteoglycan (PG) degradation.

• Restorative Dentistry and Endodontics
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• 제37권1호
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• pp.2-8
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• 2012

The limited durability of resin-dentin bonds severely compromises the longevity of composite resin restorations. Resin-dentin bond degradation might occur via degradation of water-rich and resin sparse collagen matrices by host-derived matrix metalloproteinases (MMPs). This review article provides overview of current knowledge of the role of MMPs in dentin matrix degradation and four experimental strategies for extending the longevity of resin-dentin bonds. They include: (1) the use of broadspectrum inhibitors of MMPs, (2) the use of cross-linking agents for silencing the activities of MMPs, (3) ethanol wet-bonding with hydrophobic resin, (4) biomimetic remineralization of water-filled collagen matrix. A combination of these strategies will be able to overcome the limitations in resin-dentin adhesion.

• The Korean Journal of Pain
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• 제36권1호
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• pp.72-83
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• 2023

Background: Globally, spinal cord injury (SCI) results in a big burden, including 90% suffering permanent disability, and 60%-69% experiencing neuropathic pain. The main causes are oxidative stress, inflammation, and degeneration. The efficacy of the stem cell secretome is promising, but the role of human neural stem cell (HNSC)-secretome in neuropathic pain is unclear. This study evaluated how the mechanism of HNSC-secretome improves neuropathic pain and locomotor function in SCI rat models through antioxidant, anti-inflammatory, anti-matrix degradation, and neurotrophic activities. Methods: A proper experimental study investigated 15 Rattus norvegicus divided into normal, control, and treatment groups (30 µL HNSC-secretome, intrathecal in the level of T10, three days post-traumatic SCI). Twenty-eight days post-injury, specimens were collected, and matrix metalloproteinase (MMP)-9, F2-Isoprostanes, tumor necrosis factor (TNF)-α, transforming growth factor (TGF)-β, and brain derived neurotrophic factor (BDNF) were analyzed. Locomotor recovery was evaluated via Basso, Beattie, and Bresnahan scores. Neuropathic pain was evaluated using the Rat Grimace Scale. Results: The HNSC-secretome could improve locomotor recovery and neuropathic pain, decrease F2-Isoprostane (antioxidant), decrease MMP-9 and TNF-α (anti-inflammatory), as well as modulate TGF-β and BDNF (neurotrophic factor). Moreover, HNSC-secretomes maintain the extracellular matrix of SCI by reducing the matrix degradation effect of MMP-9 and increasing the collagen formation effect of TGF-β as a resistor of glial scar formation. Conclusions: The present study demonstrated the mechanism of HNSC-secretome in improving neuropathic pain and locomotor function in SCI through antioxidant, anti-inflammatory, anti-matrix degradation, and neurotrophic activities.

• Nutrition Research and Practice
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• 제1권4호
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• pp.279-284
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• 2007

Solar ultraviolet (UV) irradiation leads to distinct changes in the skin connective tissues by degradation of collagen, which is a major structural component in the extracellular matrix. UV irradiation induces the production of matrix metalloproteinases (MMP) capable of attacking native fibrillar collagen and responsible for inhibiting the construction of collagenous extracellular matrix. In this study, we attempted to investigate the protective actions of Rubus coreanus ethanol extract (RCE) on the MMP production and the consequent procollagen/collagen degradation in UV-B-irradiated human dermal fibroblasts. The analytical data showed that Rubus coreanus ethanol extract was mostly comprised of cyanidin 3-rutinoside. Pre-treatment of fibroblasts with this extract inhibited UV-B-induced production of MMP-1, MMP-8 and MMP-13 in dose-dependent manners. In addition, Western blot analysis and immunocytochemical staining assay revealed that RCE markedly augmented the cellular levels of procollagen/collagen declined in UV-B-exposed dermal fibroblasts. These results demonstrate that RCE blocks UV-B-induced increase of the collagen degradation by inhibiting MMP production. Thus, RCE may act as an agent inhibiting excessive dermal collagen degradation leading to the skin photoaging.

• 한국신뢰성학회지:신뢰성응용연구
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• 제9권1호
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• pp.13-28
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• 2009

In this paper we propose a method for designing optimum degradation test based on nonlinear random-coefficients models. We use the approximated expression of the Fisher information matrix for nonlinear random-coefficients models. We apply the simplex algorithm to the inverse of the determinant of Fisher information matrix to satisfy the D-optimal criterion. By comparison of the results from PDP degradation data, we suggest a general guideline to obtain optimum experimental design for determining inspection intervals and number of samples in degradation testing.

• Composites Research
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• 제16권6호
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• pp.33-40
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• 2003

복합재료의 열화에 의한 미세한 손상을 실제적으로 관찰하기는 쉽지 않다. 복합재료의 열화는 심각한 blistering이 일어나기 전에 chain scission, oxidation 등의 분자적인 상변화 과정을 거쳐 모재 또는 모재와 강화제 사이의 계면에서 미세한 delamination이 발생하고 성장한다. 복합재료의 열화에 의한 초기 열손상은 기계적인 특성에 큰 영향을 주게 된다. 본 연구에서는 복합재료 부품이 열이나 화염에 단기간 노출되었을 경우 및 경화도에 따른 초음파 투과 특성을 분석하였다. 온도와 시간에 따라 열화 시험을 실시하고 초음파 탐상을 통하여 absorption coefficient를 측정한 결과 열화에 의한 미소 균열과 분자 적인 상변화에 의하여 열화도가 높을수록 높은 absorption coefficient값을 보였다 경화온도를 달리하여 경화된 복합재료의 초음파 탐상 결과 경화 온도가 높을수록 absorption coefficient 값은 높아졌으며 material velocity는 낮아지는 경향을 보였다. 이는 높은 온도에서 경화될수록 수분 및 휘발 성분에 의한 void와 같은 결함이 많이 발생하고 분자 구조적인 측면에서 높은 온도에서 경화된 경우 초음파 흡수율이 높은 망상구조가 형성되기 때문이다.

• Journal of Acupuncture Research
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• 제22권2호
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• pp.191-201
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• 2005

Background & Objective: Articular cartilage is a potential target for drugs designed to inhibit the activity of matrix metalloproteinases (MMPs) to stop or slow the destruction of the proteoglycan and collagen in the cartilage extracellular matrix. The purpose of this study was to investigate the effects of Aralia cordata Thunb. in inhibiting the release of glycosaminoglycan (GAG), the degradation of collagen, and MMP activity in rabbit articular cartilage explants. Methods : The cartilage-protective effects of Aralia cordata Thunb. were evaluated by using glycosaminoglycan degradation assay, collagen degradation assay, colorimetric analysis of MMP activity, measurement of lactate dehydrogenase activity and histological analysis in rabbit cartilage explants culture. Results : Interleukin-la (IL-1a) rapidly induced GAG, but collagen was much less readily released from cartilage explants. Aralia cordata Thunb. significantly inhibited GAG and collagen release in a concentration-dependent manner. Aralia cordata Thunb. dose-dependently inhibited MMP-3 and MMP-13 expression and activities from IL-1a-treated cartilage explants cultures when tested at concentrations ranging from 0.02 to 0.2 mg/ml. Aralia cordata Thunb. had no harmful effect on chondrocytes viability or cartilage morphology in cartilage explants. Histological analysis indicated that Aralia cordata Thunb. reduced the degradation of the cartilage matrix compared with that of IL -1a-treated cartilage explants.

• Advanced Composite Materials
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• 제18권1호
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• pp.61-75
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• 2009

The effect of porous matrix on thermal fatigue behavior of 3D-orthogonally woven SiC/SiC composite was evaluated in comparison with that having relatively dense matrix. The porous matrix yields open air passages through its thickness which can be utilized for transpiration cooling. On the other hand, the latter matrix is so dense that the air passages are sealed. A quantity of the matrix was varied by changing the number of repetition cycles of the polymer impregnation pyrolysis (PIP). Strength degradation of composites under thermal cycling conditions was evaluated by the $1200^{\circ}C$/RT thermal cycles with a combination of burner heating and air cooling for 200 cycles. It was found that the SiC/SiC composite with the porous matrix revealed little degradation in strength during the thermal cycles, while the other sample showed a 25% decrease in strength. Finally it was demonstrated that the porous structure in 3D-SiC/SiC composite improved the thermal fatigue durability.

• Journal of Nutrition and Health
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• 제38권2호
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• pp.104-111
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• 2005

Tumor invasion is composed of four steps: cell adhesion to the extracellular matrix, degradation of the extracellular matrix components, tumor cell motility followed by cell detachment. Matrix metalloproteinases (MMPs) are important proteinases that associated with degradation of matrix component. Epigallocatechin gallate (EGCG) is a major polyphenotic constituent of green tea. In the study, we examined the anti-invasive and MMP activity suppression effects of EGCG in MDA-MB-231 human breast cancer cells. MDA-MB-23l human breast cancer cells were cultured with various concentrations 0 - 100 μM of EGCG. EGCG significantly inhibited the cell adhesion to the fibronectin. Cell motility through gelatin filter and invasion to Matrigel were inhibited dose-dependently by EGCG treatment. EGCG also inhibited the activities of MMP-2, -9 and the amount of MMP-9 (α = 0.05). Therefore, EGCG may contribute to the potential beneficial food component to prevent the invasion and metastasis in breast cancer. (Korean J Nutrition 38(2): 104～111, 2005)

• 대한기계학회논문집A
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• 제29권11호
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• pp.1480-1487
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• 2005

Metal matrix composites(MMCs) have been rapidly becoming one of the strongest candidates for structural materials fur many high temperature application. However, among the various high temperature environments in which metal matrix composites was applied, thermal shock is known to cause significant degradation in most MMC system. Due to the appreciable difference in coefficient of thermal expansion(CTE) between reinforcement and metal matrix, internal stresses are generated following temperature changes. Infernal stresses affect degradation of mechanical properties of MMC by causing microscopic damage in interface and matrix during thermal cycling. Therefore, the nondestructive evaluation on thermal shock damage behavior of SiC/A16061 composite has been carried out using ultrasonics. For this study, SiC fiber reinforced metal matrix composite specimens fabricated by a squeeze casting technique were thermally cycled in the temperature range 298$\~$673 K up to 1000cyc1es. Three point bending test was conducted to investigate the efffct of thermal shock damage on mechanical properties. The relationship between thermal shock damage behavior and the propagation characteristics of surface wave and SH-ultrasonic wave was discussed by considering the result of SEM observation of fracture surface.