• 대한의용생체공학회:의공학회지
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• 제31권6호
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• pp.472-480
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• 2010

Mechanically deformed cartilage undergoes a temperature dependent phase transformation resulting in reshaping of cartilage. Laser-assisted cartilage reshaping (LCR) is recently introduced to recreate the underlying cartilage framework in structures such as ear, larynx, trachea, and nose. However, this procedure has not been fully supported by confirmed efficacy because of the lack of scientific research and its safety issues. The purpose of this study is to evaluate current laser sources to determine optimal laser wavelength for LCR using mathematical simulations and investigate optical, thermo-mechanical, and backscattering properties of cartilage after laser irradiation. The results showed that 1444 nm wavelength was effective for reshaping of cartilage with minimal thermal damage in the surrounded tissues by monte carlo simulations. Analysis of bend angle changes, thermo-mechanical characteristics, and backscattered properties may be useful to better identify the biophysical transformation responsible for stress relaxation in cartilage and develop an optical feedback control methodologies.

• 한국정밀공학회지
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• 제25권1호
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• pp.145-150
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• 2008

One of the unresolved questions in articular cartilage biomechanics is the magnitude of the dynamic modulus and tissue compressive strains under physiological loading conditions. The objective of this study was to characterize the dynamic modulus and compressive strain magnitudes of bovine articular cartilage at physiological compressive stress level and loading frequency. Four bovine calf shoulder joints (ages 2-4 months) were loaded in Instron testing system under load control, with a load amplitude up to 800 N and loading frequency of 1 Hz, resulting in peak engineering stress amplitude of ${\sim}5.8\;MPa$. The corresponding peak deformation of the articular layer reached ${\sim}27%$ of its thickness. The effective dynamic modulus determined from the slope of stress versus strain curve was ${\sim}23\;MPa$, and the phase angle difference between the applied stress and measured strain which is equivalent to the area of the hystresis loop in the stress-strain response was ${\sim}8.3^{\circ}$. These results are representative of the functional properties of articular cartilage in a physiological loading environment. This study provides novel experimental findings on the physiological strain magnitudes and dynamic modulus achieved in intact articular layers under cyclical loading conditions.

• 대한의용생체공학회:의공학회지
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• 제28권2호
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• pp.169-173
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• 2007

During laser irradiation, mechanically deformed cartilage undergoes a temperature dependent phase transformation resulting in accelerated stress relaxation. Clinically, laser-assisted cartilage reshaping may be used to recreate the underlying cartilaginous framework in structures such as ear, larynx, trachea, and nose. Therefore, research and identification of the biophysical transformations in cartilage accompanying laser heating are valuable to identify critical laser dosimetry and phase transformation of cartilage for many clinical applications. quasi-elastic light scattering was investigated using Ho : YAG laser $(\lambda=2.12{\mu}m\;;\;t_p\sim450{\mu}s)$ and Nd:YAG Laser $(\lambda=1.32{\mu}m\;;\;t_p\sim700{\mu}s)$ for heating sources and He : Ne $(\lambda=632.8nm)$ laser, high-power diode pumped laser $(\lambda=532nm)$, and Ti : $Al_2O_3$ femtosecond laser $(\lambda=850nm)$ for light scattering sources. A spectrometer and infrared radiometric sensor were used to monitor the backscattered light spectrum and transient temperature changes from cartilage following laser irradiation. Analysis of the optical, thermal, and quasi-elastic light scattering properties may indicate internal dynamics of proteoglycan movement within the cartilage framework during laser irradiation.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.1425-1426
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• 2011

• Maxillofacial Plastic and Reconstructive Surgery
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• 제15권4호
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• pp.303-316
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• 1993

The auricular cartilage grafts have been widely used in replacement of the temporomandibular joint disk. Cartilage grafts itself have a low metabolism and high survival rate after grafting. In processing the grafting materials, it was important to preserve the properties of chondrocyte proper. We used 15% glycerol and 10% DMSO (Dimethyl Sulfoxide) solutions for cartilage fixation before deep freezing. We have performed the allogenic auricular cartilage graft in the temporomandibular joint of 20 rabbits which 10 specimen was treated with 15% glycerol and the other 10 specimen was treated with 10% DMSO respectively and examined in 1, 2, 4, 6 and 8 weeks after operation histopathologically. The result were : 1. Inflammatory cell infiltration around the grafted material appeared more glycerol groups than DMSO groups at 1 week, but each group has no differences after 2 weeks. 2. Degenerative changes of grafted auricular chondrocytes were more deveolped in glycerol group than DMSO groups till 4 weeks, but there were no differences between two groups after 6 weeks. 3. Fibrous union between grafted fragment and mandibular condyle was prominent in DMSO group. 4. Vascular proliferation of the grafted auricualr cartilage was more developed in DMSO groups than glycerol group in early stage. 5. Amount of the additional growth of grafted auricular cartilage was more existed in DMSO groups than glycerol group. 6. General survival rate after grafting was more prominent in DMSO group. In summary, allogenic auricular cartilage grafts treated with 15% glycerol and 10% DMSO solution have supported to survivalbility as a cryopreservative agents, especially DMSO groups have little inflammatory cell infiltration in early stages and degenerative changes and additional growth are more prominent than glycerol groups.

• Tissue Engineering and Regenerative Medicine
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• 제15권6호
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• pp.673-697
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• 2018

BACKGROUND: Cartilage tissue engineering (CTE) aims to obtain a structure mimicking native cartilage tissue through the combination of relevant cells, three-dimensional scaffolds, and extraneous signals. Implantation of 'matured' constructs is thus expected to provide solution for treating large injury of articular cartilage. Type I collagen is widely used as scaffolds for CTE products undergoing clinical trial, owing to its ubiquitous biocompatibility and vast clinical approval. However, the long-term performance of pure type I collagen scaffolds would suffer from its limited chondrogenic capacity and inferior mechanical properties. This paper aims to provide insights necessary for advancing type I collagen scaffolds in the CTE applications. METHODS: Initially, the interactions of type I/II collagen with CTE-relevant cells [i.e., articular chondrocytes (ACs) and mesenchymal stem cells (MSCs)] are discussed. Next, the physical features and chemical composition of the scaffolds crucial to support chondrogenic activities of AC and MSC are highlighted. Attempts to optimize the collagen scaffolds by blending with natural/synthetic polymers are described. Hybrid strategy in which collagen and structural polymers are combined in non-blending manner is detailed. RESULTS: Type I collagen is sufficient to support cellular activities of ACs and MSCs; however it shows limited chondrogenic performance than type II collagen. Nonetheless, type I collagen is the clinically feasible option since type II collagen shows arthritogenic potency. Physical features of scaffolds such as internal structure, pore size, stiffness, etc. are shown to be crucial in influencing the differentiation fate and secreting extracellular matrixes from ACs and MSCs. Collagen can be blended with native or synthetic polymer to improve the mechanical and bioactivities of final composites. However, the versatility of blending strategy is limited due to denaturation of type I collagen at harsh processing condition. Hybrid strategy is successful in maximizing bioactivity of collagen scaffolds and mechanical robustness of structural polymer. CONCLUSION: Considering the previous improvements of physical and compositional properties of collagen scaffolds and recent manufacturing developments of structural polymer, it is concluded that hybrid strategy is a promising approach to advance further collagen-based scaffolds in CTE.

• 대한관절경학회지
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• 제13권3호
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• pp.189-192
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• 2009

Although the articular cartilage is only a few milimiters thick, it has surprising stiffness to compression, exceptional ability to distribute load minimizing peak stress on subchondral bone and great durability. In many instances, it help to preserve normal joint function for more than 80 years. Varying in thickness, cell density, matrix composition, mechanical properties even within the same joint, it provides low-friction and pain free-motion. However, it lacks a blood or lymphatic supply and neurological elements are absent. It shows limited healing potential because of poor regenerative capacity.

• The Journal of Korean Physical Therapy
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• 제16권2호
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• pp.1-16
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• 2004

관절연골은 우리의 일상생활중 또는 스포츠나 여가활동과 같이 다양한 활동중에 발생되는 역학적 부하를 조절하는 기능적 구성요소이다. 관절연골의 구성과 생화학적 구조 및 물리학적 특성간 사이의 상호작용은 적은 마찰과, 마모에 저항하는 성실, 충격의 흡수와 분산에 중요한 역할을 한다. 그러나 이 관절연골의 퇴행성 변화가 발생하게 되면 관절연골 자체의 기능장해 뿐만 아니라 관절의 다른 구성요소에도 손상을 축적시키게 되어 종국에는 관절 전체 구성요소의 장애와 기능적 수준의 감소로 이끌어간다. 관절연골의 퇴행을 일으키는 원인으로는 외상, 퇴행성질환, 류마티스질환 신경근질환, 관절구축등 여러 가지 질병으로 인하여 발생될 수 있다. 그러나 이러한 질병을 중재하고 치료하기 위하여 역학적 부하나 관절가동을 제한하는 고정도 연골의 생합성기능에 영향을 미쳐 연골의 퇴행성 변화를 촉진하게 된다. 건강한 기능을 수행하기 위해서는 적절한 관절부하와 관절운동을 통한 역학적 자극이 제공되어야 하며 물리치료영역에서 접하는 고정환자에 대한 적절한 역학적 자극 제공 방안이 마련되어야 할 것이다.

• IMMUNE NETWORK
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• 제14권1호
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• pp.45-53
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• 2014

Osteoarthritis (OA) is a degenerative joint disease characterized by a progressive loss of cartilage. And, increased oxidative stress plays a relevant role in the pathogenesis of OA. Ursodeoxycholic acid (UDCA) is a used drug for liver diseases known for its free radical-scavenging property. The objectives of this study were to investigate the in vivo effects of UDCA on pain severity and cartilage degeneration using an experimental OA model and to explore its mode of actions. OA was induced in rats by intra-articular injection of monosodium iodoacetate (MIA) to the knee. Oral administration UDCA was initiated on the day of MIA injection. Limb nociception was assessed by measuring the paw withdrawal latency and threshold. Samples were analyzed macroscopically and histologically. Immunohistochemistry was used to investigate the expression of interleukin-$1{\beta}$ (IL-$1{\beta}$), IL-6, nitrotyrosine and inducible nitric oxide synthase (iNOS) in knee joints. UDCA showed an antinociceptive property and attenuated cartilage degeneration. OA rats given oral UDCA significantly exhibited a decreased number of osteoclasts in subchondral bone legion compared with the vehicle-treated OA group. UDCA reduced the expression of IL-$1{\beta}$, IL-6, nitrotyrosine and iNOS in articular cartilage. UDCA treatment significantly attenuated the mRNA expression of matrix metalloproteinase-3 (MMP-3), -13, and ADAMTS5 in IL-$1{\beta}$-stimulated human OA chondrocytes. These results show the inhibitory effects of UDCA on pain production and cartilage degeneration in experimentally induced OA. The chondroprotective properties of UDCA were achieved by suppressing oxidative damage and inhibiting catabolic factors that are implicated in the pathogenesis of cartilage damage in OA.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1265-1270
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• 2007

Conventional methods for fabricating three-dimensional (3-D) scaffolds have substantial limitations. In this paper, we present 3-D scaffolds that can be made repeatedly with the same dimensions using a microstereolithography system. This system allows the fabrication of a pre-designed internal structure, such as pore size and porosity, by stacking photopolymerized materials. The scaffolds must be manufactured in a material that is biocompatible and biodegradable. In this regard, we synthesized liquid photocurable biodegradable TMC/TMP, followed by acrylation at terminal ends. And also, solidification properties of TMC/TMP polymer are to be obtained through experiments. Cell adhesion to scaffolds significantly affects tissue regeneration. As a typical example, we seeded chondrocytes on two types of 3-D scaffold and compared the adhesion results. Based on these results, the scaffold geometry is one of the most important factors in chondrocyte adhesion. These 3-D scaffolds could be key factors for studying cell behavior in complex environments and eventually lead to the optimum design of scaffolds for the regeneration of various tissues, such as cartilage and bone.