| 1. |
Shinichi Nakagawa, Wataru Ando, Kazunori Shimomura, David A Hart, Hiroto Hanai, George Jacob, Ryota Chijimatsu, Seido Yarimitsu, Hiromichi Fujie, Seiji Okada, Noriyuki Tsumaki, Norimasa Nakamura, Repair of osteochondral defects: efficacy of a tissue-engineered hybrid implant containing both human MSC and human iPSC-cartilaginous particles, NPJ Regenerative Medicine, 10.1038/s41536-023-00335-x, 8, 1, 59, 2023.10. |
| 2. |
Nečas, D., Yarimitsu, S., Rebenda, D., Shinmori, H., Vrbka, M., Sawae, Y., Murakami, T. & Křupka, I, On the replacement of articular cartilage: The friction of PVA hydrogel layer in hip simulator test, Tribology International, 10.1016/j.triboint.2022.108100, 178, 108100, 2023.02. |
| 3. |
Takashi Kamatani, Hiroki Hagizawa, Seido Yarimitsu, Miho Morioka, Saeko Koyamatsu, Michihiko Sugimoto, Joe Kodama, Junko Yamane, Hiroyuki Ishiguro, Shigeyuki Shichino, Kuniya Abe, Wataru Fujibuchi, Hiromichi Fujie, Takashi Kaito, Noriyuki Tsumaki, Human iPS cell-derived cartilaginous tissue spatially and functionally replaces nucleus pulposus, Biomaterials, 10.1016/j.biomaterials.2022.121491, 284, 121491-121491, 2022.05. |
| 4. |
David Rebenda, Martin Vrbka, David Nečas, Evgeniy Toropitsyn, Seido Yarimitsu, Pavel Čípek, Martin Pravda, Martin Hartl, Rheological and frictional analysis of viscosupplements towards improved lubrication of human joints, Tribology International, 10.1016/j.triboint.2021.107030, 160, 107030-107030, 2021.08. |
| 5. |
Teruo Murakami, Nobuo Sakai, Seido Yarimitsu, Kazuhiro Nakashima, Tetsuo Yamaguchi, Yoshinori Sawae, Atsushi Suzuki, Evaluation of influence of changes in permeability with aging on friction and biphasic behaviors of artificial hydrogel cartilage, Biotribology, 10.1016/j.biotri.2021.100178, 26, 100178-100178, 2021.06. |
| 6. |
Seido Yarimitsu, Kei Ito, Hiromichi Fujie, Influence of collagen fibre orientation on the frictional properties of articular cartilage, Biosurface and Biotribology, 10.1049/bsb2.12005, 2021.05.  |
| 7. |
Shoko Horibata, Seido Yarimitsu, Hiromichi Fujie, Effect of Synovial Fluid Pressurization on the Biphasic Lubrication Property of Articular Cartilage, Biotribology, 19, 100098, 2019.07. |
| 8. |
Nobuo Sakai, Seido Yarimitsu, Yoshinori Sawae, Mochimitsu Komori, Teruo Murakami, Biomimetic artificial cartilage: fibre-reinforcement of PVA hydrogel to promote biphasic lubrication mechanism, Biosurface and Biotribology, 5, 1, 13-19, 2019.04. |
| 9. |
Hiroyuki Ishiguro, Takashi Kaito, Seido Yarimitsu, Kunihiko Hashimoto, Rintaro Okada, Junichi Kushioka, Ryota Chijimatsu, Shota Takenaka, Takahiro Makino, Yusuke Sakai, Yu Moriguchi, Satoru Otsuru, David A. Hart, Hiromichi Fujie, Norimasa Nakamura, Hideki Yoshikawa, Intervertebral disc regeneration with an adipose mesenchymal stem cell-derived tissue-engineered construct in a rat nucleotomy model, Acta Biomaterialia, 10.1016/j.actbio.2019.01.050, 87, 118-129, 2019.03, © 2019 Acta Materialia Inc. Low back pain results in more global disabilities than any other condition, and intervertebral disc (IVD) degeneration is commonly involved in the etiology. Supplementation of IVDs with reparative cells is a rational strategy to address such clinical problems. We have previously developed a scaffold-free tissue-engineered construct (TEC) as a novel cell therapy system for repair of articular cartilage and meniscus. We now show the regenerative potential of adipose mesenchymal stem cells derived TEC (ADSC-TEC) for IVD degeneration using a rat tail model of total nucleotomy. The regenerative efficacy of ASDC-TEC was investigated structurally and biomechanically up to 6 months after implantation. ADSC-TEC implantation into IVDs preserved the disc height, endplate, and annulus fibrosus structure, and showed similar biomechanical characteristics to the sham group at postoperative 6 weeks. The structure of regenerated IVD was maintained until 6 months. Furthermore, ADSC-TEC implantation attenuated the impact of age-related biomechanical deterioration when assessed at 6 months post-implantation. These results demonstrate that use of ADSC-TECs can be an effective treatment for IVD degeneration. Statement of significance: We developed adipose mesenchymal stem cell-derived scaffold-free tissue engineered construct (ADSC-TEC) as a novel cell therapy system. The ADSC-TEC implantation into a rat total-nucleotomized disc space regenerated intervertebral discs (IVDs) histologically and biomechanically. The regenerative capacity of the ADSC-TEC was exerted by its trophic effects on annulus fibrosus cells and the load-sharing effect at intervertebral space. Interestingly, the regenerated IVDs by the ADSC-TEC was less susceptible to the age-related deterioration than the IVDs of normal rats. Thus, the application of ADSC-TEC into the degenerated disc can be an alternative therapy for various disease associated with structural and functional failure of IVDs.. |
| 10. |
Shoko Horibata, Seido Yarimitsu, Hiromichi Fujie, Influence of Synovial Fluid Pressure on Biphasic Lubrication Property in Articular Cartilage, Tribology Online, 13, 3, 172-177, 2018.07. |
| 11. |
Hiromichi Fujie, Sou Morishita, Seido Yarimitsu, Effect of Collagen-Induced Residual Stress on the Frictional Property of Articular Cartilage, Biosurface and Biotribology, 4, 2, 68-71, 2018.06. |
| 12. |
Nobuo Sakai, Seido Yarimitsu, Yoshinori Sawae, Mochimitsu Komori, Teruo Murakami, Transitional behaviour between biphasic lubrication and soft elastohydrodynamic lubrication of poly(vinyl alcohol) hydrogel using microelectromechanical system pressure sensor, Biosurface and Biotribology, 4, 1, 24-33, 2018.03. |
| 13. |
Teruo Murakamia, Seido Yarimitsu, Nobuo Sakai, Kazuhiro Nakashima, Tetsuo Yamaguchi, Yoshinori Sawae, Importance of adaptive multimode lubrication mechanism in natural synovial joints, TRIBOLOGY INTERNATIONAL, 10.1016/j.triboint.2016.12.052, 113, 306-315, 2017.09, The superior tribological performance in natural synovial joints with low friction and minimal wear appears to be actualized by not single lubrication mode but the synergistic combination of various modes from the fluid film lubrication to boundary lubrication corresponding to the severity of rubbing conditions. We have conducted the biphasic finite element analysis and some experimental studies for articular cartilage to elucidate this ingenious lubrication mechanism from the viewpoint of the adaptive multimode lubrication mechanism. In this paper, the effectiveness of different lubrication modes such as biphasic, boundary, gel-film and hydration lubrication particularly at low speed conditions is discussed.. |
| 14. |
Teruo Murakami, Seido Yarimitsu, Nobuo Sakai, Kazuhiro Nakashima, Tetsuo Yamaguchi, Yoshinori Sawae, Atsushi Suzuki, Superior lubrication mechanism in poly(vinyl alcohol) hybrid gel as artificial cartilage, PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY, 10.1177/1350650117712881, 231, 9, 1160-1170, 2017.09, With recent progress of material technologies, the wear resistance of ultra-high molecular weight polyethylene for total joint prostheses has been improved, but under severe conditions friction and wear problems have not yet been completely solved. Therefore, the application of artificial hydrogel cartilage with similar properties to natural articular cartilage is expected to solve the friction and wear problems by improvement of lubrication mechanism with superior tribological functions. In this study, reciprocating tests of four kinds of poly(vinyl alcohol) hydrogels were carried out and the biphasic finite element analysis was conducted. As artificial cartilage specimens, four kinds of poly(vinyl alcohol) hydrogels were prepared using the repeated freeze-thawing (FT) method, the cast-drying (CD) method and the hybrid method with different layered structure as FT on CD or CD on FT. In reciprocating test of ellipsoidal poly(vinyl alcohol) hydrogel specimen against flat glass plate in saline solution, four kinds of hydrogels exhibited very different frictional levels as hybrid (CD on FT) |
| 15. |
Evaluation of Lubrication Property of Hydrogel Artificial Cartilage Rubbed Against Natural Articular Cartilage. |
| 16. |
Shuichiro Uehara, Seido Yarimitsu, Toru Moro, Masayuki Kyomoto, Kenichi Watanabe, Sakae Tanaka, Kazuhiko Ishihara, Teruo Murakami, Evaluation of wear suppression for phospholipid polymer-grafted ultra-high molecular weight polyethylene at concentrated contact, TRIBOLOGY INTERNATIONAL, 10.1016/j.triboint.2016.04.026, 101, 264-272, 2016.09, The wear resistance of cross-linked polyethylene grafted with poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC-grafted CLPE) and unmodified CLPE loaded by an alumina roller were evaluated in a simulated synovial fluid (0.5 wt% hyaluronate solution containing 30 vol% fetal bovine serum). To evaluate the wear depth distribution within the wear scar, we compared the projected area of wear and non wear for indents on polyethylene surfaces, produced by a triangular pyramidal indenter and estimated the local wear depths on the basis of the changes in the projected area. The worn depth of PMPC-grafted CLPE was almost a third lower than that on CLPE. (C) 2016 Elsevier Ltd. All rights reserved.. |
| 17. |
Biphasic FE Analysis of Fiber-reinforced PVA Hydrogel for Artificial Cartilage Material. |
| 18. |
Seido Yarimitsu, Ayumi Yoshida, Saori Sasaki, Teruo Murakami, Atsushi Suzuki, Evaluation of lubrication property of poly(vinyl alcohol) hybrid gel for artificial articular cartilage, Tribology Online, 10.2474/trol.11.360, 11, 2, 360-365, 2016.04. |
| 19. |
Seido Yarimitsu, Saori Sasaki, Teruo Murakami, Atsushi Suzuki, Evaluation of lubrication properties of hydrogel artificial cartilage materials for joint prosthesis, Biosurface and Biotribology, 10.1016/j.bsbt.2016.02.005, 2, 1, 40-47, 2016.03. |
| 20. |
Effect of drying on the frictional properties of PVA cast gel
© 2015, The Society of Polymer Science, Japan. The frictional properties of PVA cast gel prepared under different conditions have been investigated. Optimum drying humidity (60%RH) or low drying temperature conditions caused a decrease in the coefficient of friction in the reciprocating test. As the drying humidity increased, the surface of the gel became flat and smooth. On the other hand, when the drying temperature became lower, lubrication improved by elution of the polymer. In addition, the layered PVA cast gel maintained a lower coefficient of friction throughout the reciprocating test. From the results, it was shown that the excellent frictional properties could be maintained by controlling the preparation conditions.. |
| 21. |
ハイドロゲル人工軟骨の生体内固定法と安定性の評価
ハイドロゲル人工軟骨の生体内固定法と安定性について検討した。ケン化度98.4～99.8mol%、重合度約2000のPVAを原料とし、20wt%PVA水溶液を反復凍結法にてゲル化させ、弾性率約1.2MPa、含水率79%のPVAハイドロゲルを作製した。検体は生後28週程度の日本白色家兎を用いた。術後8週以降からCT像にて確認可能なPVAハイドロゲル貫通孔への骨侵入の形跡を確認し、術後24週においては明瞭な骨形成を確認した。PVAハイドロゲル埋込部表面に形成された組織は一部サフラニンOによる赤色の被染色部位が部分的にみられ、軟骨基質の存在が確認できるが、ファストグリーンによる青色の被染色部位がより強くみられ、骨基質が多く存在していることを確認した。PVAハイドロゲル埋入部周辺は骨梁構造が緻密化する傾向がみられた。. |
| 22. |
Seido Yarimitsu, Toru Moro, Masayuki Kyomoto, Kenichi Watanabe, Sakae Tanaka, Kazuhiko Ishihara, Teruo Murakami, Influences of dehydration and rehydration on the lubrication properties of phospholipid polymer-grafted cross-linked polyethylene, PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART H-JOURNAL OF ENGINEERING IN MEDICINE, 10.1177/0954411915588969, 229, 7, 506-514, 2015.07, Surface modification by grafting of biocompatible phospholipid polymer onto the surface of artificial joint material has been proposed to reduce the risk of aseptic loosening and improve the durability. Poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC)-grafted cross-linked polyethylene (CLPE) has shown promising results for reducing wear of CLPE. The main lubrication mechanism for the PMPC layer is considered to be the hydration lubrication. In this study, the lubrication properties of PMPC-grafted CLPE were evaluated in reciprocating friction test with rehydration process by unloading in various lubricants. The start-up friction of PMPC-grafted CLPE was reduced, and the damage of PMPC layer was suppressed by rehydration in water or hyaluronic acid solutions. In contrast, the start-up friction of PMPC-grafted CLPE increased in fetal bovine serum solution, and the damage for PMPC layer was quite noticeable. Interestingly, the start-up friction of PMPC-grafted CLPE was reduced in fetal bovine serum solution containing hyaluronic acid, and the damage of the PMPC layer was suppressed. These results indicate that the rehydration by unloading and hyaluronic acid are elemental in maximizing the lubrication effect of hydrated PMPC layer.. |
| 23. |
Teruo Murakami, Seido Yarimitsu, Kazuhiro Nakashima, Yoshinori Sawae, Nobuo Sakai, Erratum to: Influence of synovia constituents on tribological behaviors of articular cartilage (Friction, 1, 2, 2013 (150-162), 10.1007/s40544-013-0010-6), Friction, 10.1007/s40544-014-0065-z, 2, 4, 391, 2014.12, The original version of this article unfortunately contained the incorrect lengend “(Formula presented.)HA 0.5 wt% + DPPC 0.01 wt% +albumin 1.4 wt%” in Fig. 7 on page 155, instead of, (Figure presented.). It should read (Figure presented.).. |
| 24. |
Teruo Murakami, Seido Yarimitsu, Kazuhiro Nakashima, Tetsuo Yamaguchi, Yoshinori Sawae, Nobuo Sakai, Atsushi Suzuki, Superior lubricity in articular cartilage and artificial hydrogel cartilage, PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY, 10.1177/1350650114530273, 228, 10, 1099-1111, 2014.10, In healthy natural synovial joints, the extremely low friction and minimum wear are maintained by their superior load-carrying capacity and lubricating ability. This superior lubricating performance appears to be actualized not by single lubrication mode but by synergistic combination of multimode mechanisms such as fluid film, biphasic, hydration, gel film and/or boundary lubrication. On the contrary, in most artificial joints composed of ultra-high molecular weight polyethylene against metal or ceramic-mating material, boundary and/or mixed lubrication modes prevail and thus local direct contact brings down high friction and high-wear problems. To extend the durability of artificial joint, the reduction in friction and wear by improvement in lubrication mechanism is required as an effective design solution. In this paper, at the start, the mechanism of superior lubricity for articular cartilage is examined from the viewpoints of biphasic and boundary lubrication mechanism. Subsequently, the proposal of biomimetic artificial hydrogel cartilage is put forward to improve the lubricating modes in artificial joints. The tribological behaviours in two kinds of poly(vinyl alcohol) hydrogels are compared with that of natural cartilage. The importance in lubrication mechanism in artificial hydrogel cartilage is discussed.. |
| 25. |
Seido Yarimitsu, Kazuhiro Nakashima, Yoshinori Sawae, Teruo Murakami, Influence of Phospholipid and Protein Constituents on Tribological Properties of Artificial Hydrogel Cartilage Material, Journal of Biomechanical Science and Engineering, Vol.8, No.3, 257-267, 2013.09. |
| 26. |
Seido Yarimitsu, Kazuhiro Nakashima, Yoshinori Sawae, Teruo Murakami, Influence of phospholipid and protein constituents on tribological properties of artificial hydrogel cartilage material, Journal of Biomechanical Science and Engineering, 10.1299/jbse.8.257, 8, 3, 257-267, 2013.09, In this study, the influence of phospholipid and protein constituents on friction and wear behavior of artificial hydrogel cartilage was investigated. A sliding pair of an ellipsoidal specimen of poly (vinyl alcohol) (PVA) hydrogel and a flat specimen of PVA hydrogel was evaluated in simplified reciprocating friction test. Dipalmitoylphosphatidylcholine (DPPC) was selected as a phospholipid constituent and was dispersed in saline as liposome. Fluorescent-labeled albumin and γ-globulin were used as protein constituents in lubricants at concentration of 0.7 wt%. After reciprocating friction test, the boundary film formed on the surface of PVA hydrogel and the worn surface of PVA hydrogel were observed by using fluorescent microscope and confocal laser scanning microscope, respectively. When only albumin or γ-globulin was added to lubricant, adhesive wear pattern was frequently observed and large breaking-offof surface structure of PVA hydrogel occurred. Lubricants that contain both proteins and 0.01wt% DPPC showed reduction of friction and suppression of large breaking-offof surface structure of PVA hydrogel. Meanwhile, under coexistence of protein and 0.02wt% DPPC, friction increased compared to that for lubricants that contain 0.01wt% DPPC and the adhesive wear patterns became obvious. Therefore, both the concentration and the relative ratio of proteins to phospholipids are important factors to function adequately as excellent boundary lubricant for PVA hydrogel. © 2013 by JSME.. |
| 27. |
Teruo Murakami, Seido Yarimitsu, Kazuhiro Nakashima, Yoshinori Sawae, Nobuo Sakai, Influence of synovia constituents on tribological behaviors of articular cartilage, FRICTION, 10.1007/s40544-013-0010-6, 1, 2, 150-162, 2013.06, The extremely low friction and minimal wear in natural synovial joints appear to be established by effective lubrication mechanisms based on appropriate combination of articular cartilage and synovial fluid. The complex structure of cartilage composed of collagen and proteoglycan with high water content contributes to high load-carrying capacity as biphasic materials and the various constituents of synovial fluid play important roles in various lubrication mechanisms. However, the detailed differences in functions of the intact and damaged cartilage tissues, and the interaction or synergistic action of synovia constituents with articular cartilage have not yet been clarified. In this study, to examine the roles of synovia constituents and the importance of cartilage surface conditions, the changes in friction were observed in the reciprocating tests of intact and damaged articular cartilage specimens against glass plate lubricated with lubricants containing phospholipid, protein and/or hyaluronic acid as main constituents in synovial fluid. The effectiveness of lubricant constituents and the influence of cartilage surface conditions on friction are discussed. In addition, the protectiveness by synovia constituents for intact articular cartilage surfaces is evaluated.. |
| 28. |
Junji Ikeda, Mikio Iwamoto, Seido Yarimitsu, Teruo Murakami, Differences in kinetics of phase transformation of 3Y-TZP ceramics between aging test under hydrothermal environment and hip simulator wear test, Journal of Biomechanical Science and Engineering, 10.1299/jbse.7.199, 7, 2, 199-200, 2012.03, The phase stability of yttria (3 mol%) stabilized tetragonal polycrystalline zirconia (3Y-TZP) has been evaluated by X-ray diffraction and laser microscope. The differences in kinetics of phase transformation in the aging test under hydrothermal environment and during the hip simulator wear test were compared. It was found that the phase transformation during aging test experiences a Mehl-Avrami-Johnson (MAJ) equation and the phase stability of tetragonal phase can be improved by controlling the sintering condition. Hip simulator wear test using zirconia femoral head with 4 different monoclinic fractions was performed against conventional UHMWPE (GUR 1050) acetabular socket up to 6 million cycles. During hip simulator testing, slight increase in monoclinic fraction of some zirconia femoral head was observed. Increasing rate of monoclinic phase depended on initial monoclinic fraction. But, from the result of measurement of UHMWPE wear rate, mutual relationship between the monoclinic fraction on zirconia femoral head and the wear rate of UHMWPE socket was not observed. From the results of laser microscope observation, in the case of phase transformation during hip simulator test, large number of small monoclinic spots were observed in contrast to the phase transformation during aging test. Moreover an increase in monoclinic fraction on the surface alone was observed significantly compared to the progress into the bulk in aging test. These facts indicate that the nucleation of monoclinic phase on the surface was enhanced by the sliding action against UHMWPE cup. Thus, it was suggested that the phase transformation during hip simulator test was affected on tribochemical reaction during sliding condition. © 2012 by JSME.. |
| 29. |
T. Murakami, K. Nakashima, S. Yarimitsu, Y. Sawae, N. Sakai, Effectiveness of adsorbed film and gel layer in hydration lubrication as adaptive multimode lubrication mechanism for articular cartilage, PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY, 10.1177/1350650111415756, 225, J12, 1174-1185, 2011.12, With various daily activities, the effectiveness of adsorbed film formed on a gel-like layer at the uppermost superficial articular cartilage in natural synovial joints becomes important to control the friction and wear of articular cartilage in mixed or boundary lubrication regime as an adaptive multimode lubrication mechanism. Furthermore, in the case where the adsorbed film has been removed, the proteoglycan gel layer is expected to preserve low friction and protect against the wear of bulk cartilage tissue with an effective hydration lubrication mechanism. Besides, it is indicated that the biphasic lubrication plays an important role in lowering of friction in articular cartilage containing a large amount of water. At the present stage, however, the detailed relationship between adsorbed films and hydrated gel layers has not yet been elucidated. In this article, the frictional behaviours of articular cartilage on a glass plate were observed in the reciprocating tests with the restarting process after interruption and unloading. The lubricating effectiveness of adsorbed films in hyaluronate (HA) solutions was examined using intact and partially damaged cartilage specimens. The role of albumin and g-globulin in relation to the surface conditions of gel layer is discussed. The restarting friction immediately after reloading became lower as a result of recovery of the effective interstitial fluid pressurization and hydration and adsorbed films have a significant effect on the frictional behaviour at local contacts. To clarify the molecular phenomena taking place under rubbing condition, in situ observations of the forming adsorbed film were conducted. The measurements were performed using the fluorescent staining method for protein and HA molecules at low contact pressures.. |
| 30. |
The role of subchondral tissues on lubrication properties of natural articular cartilage
Excellent lubrication properties of natural synovial joints are considered to be due to the adaptive multimode lubrication mechanism, in which various lubrication mechanisms functioned synergistically and hierarchically. In those lubrication mechanisms, hydration lubrication by the proteoglycan gel layer at the superficial zone of articular cartilage and the biphasic lubrication mechanism by the biphasic nature of articular cartilage are influenced by the extent of hydration and behavior of internal fluid in osteochondral tissues. In recent studies, possibilities of transport of fluid between cartilage layer and underlying tissues were indicated. Therefore, the influences of subchondral tissues on lubricating properties of natural articular cartilage were examined. Reciprocating friction test was conducted by using a sliding pair of cylindrical natural articular cartilage with various thickness of subchondral tissues and glass plate. Normal saline and saline solutions of albumin and γ-globulin were selected as test lubricants. It was found that cartilage specimen with thick subchondral tissues showed lower friction and cartilage specimen with thin subchondral tissues showed higher friction when saline and saline solutions of albumin and γ-globulin were used as lubricants. The remaining of the surface gel layer of articular cartilage was observed after friction test by atomic force microscope. In addition, there was no difference in changes of contact area against loading time between cartilage specimens with or without subchondral tissues. Considering the possibilities of transport of fluid between cartilage layer and subchondral tissues, it is considered that fluid transfer between cartilage layer and subchondral tissues influences on the extent of hydration, the behavior of internal fluid in osteochondral tissues and the functionalities of surface gel hydration lubrication and biphasic lubrication mechanisms. These findings indicated that subchondral tissues have an important role on maintaining the excellent lubricating ability of articular cartilage. © 2010 International Federation for Medical and Biological Engineering.. |
| 31. |
リン脂質二分子膜が人工軟骨候補材料の摩擦挙動に与える影響
リン脂質オリゴラメラによるポリビニルアルコール(PVA)ハイドロゲルの摩擦低減機構を解明するために、リン脂質二分子膜をモデル膜として相手側摩擦面に付与することにより、リン脂質二分子膜がPVAハイドロゲルの摩擦挙動に与える影響を調査した。摩擦試験開始直後は摩擦係数0.07以下の低摩擦を示したが、ジパルミトイルホスファチジルコリン(DPPC)を含有しない潤滑液A、C、Dについては滑り距離の増加とともに摩擦係数が上昇した。DPPCおよび他のリン脂質成分を含む潤滑液B、Eを用いた場合、滑り距離の増加に伴う摩擦係数の上昇は他の潤滑液と比較して抑制された。DPPC二分子膜コートの場合、摩擦試験開始直後には、全ての潤滑液において顕著に摩擦が低減したが、蛋白質のみを含む潤滑液C、D中においては摩擦低減効果が得られなかった。. |
| 32. |
Influences of Synovia Constituents on Frictional Behavior of Artificial Cartilage Material and Formation of Boundary Lubricating Film
Frictional behavior of poly (vinyl alcohol)(PVA) hydrogel as artificial articular cartilage was examined in reciprocating motion in lubricants that contain albumin, gamma-globulin, L-alpha dipalmitoyl phosphatidylcholine (DPPC) and hyaluronic acid (HA). Influences of synovia constituents on forming boundary film and boundary lubrication ability for PVA hydrogel were investigated by in situ fluorescent observation on forming boundary film, atomic force microscopy and infrared spectroscopy. Under the coexistence of proteins and DPPC, DPPC contributed to reduce friction of PVA hydrogel. Albumin-DPPC composite film and smooth film formed by DPPC especially reduced friction. When HA and DPPC coexist in the lubricants, HA-DPPC composite film with micron-ordered pattern was formed and it reduced friction remarkably. Through the researches on the influences of synovia constituents on boundary lubricating ability for PVA hydrogel, it was shown that albumin and DPPC function as low shearing resistance components in boundary film and gamma-globulin has ability to stabilize boundary film and enhances the formation of boundary film. HA has high ability of water retention and plays a part in reduction of friction and enhancement of forming boundary film that has the characteristics of gel-like layer.. |
| 33. |
Seido Yarimitsu, Kazuhiro Nakashima, Yoshinori Sawae, Teruo Murakami, Influences of lubricant composition on forming boundary film composed of synovia constituents, TRIBOLOGY INTERNATIONAL, 10.1016/j.triboint.2008.11.005, 42, 11-12, 1615-1623, 2009.12, In this study, the influences of lubricant composition on adsorption behavior of proteins and stability of protein boundary film were investigated by using total internal reflection fluorescence microscopy (TIRFM). In addition, the adsorption of hyaluronic acid (HA) on rubbed surface was also observed. It was found that the forming of bottom layer of protein boundary film mainly composed of gamma-globulin is a key factor to form a stable boundary film and the friction-induced enhancement of forming protein boundary film occurred in appropriate lubricant. In addition, the adsorption of HA on rubbed surface was enhanced by coexistence with gamma-globulin and frictional action. It was indicated that a gel-like film is formed due to the introduction of hydrophilic HA molecules into boundary film and it contributes to reduce friction. (C) 2008 Elsevier Ltd. All rights reserved.. |
| 34. |
YARIMITSU Seido, NAKASHIMA Kazuhiro, SAWAE Yoshinori, MURAKAMI Teruo, Effects of Lubricant Composition on Adsorption Behavior of Proteins on Rubbing Surface and Stability of Protein Boundary Film, Tribol Online (Web), 10.2474/trol.3.238, 3, 4, 238-242 (J-STAGE), 2008.08. |
| 35. |
YARIMITSU Seido, NAKASHIMA Kazuhiro, SAWAE Yoshinori, MURAKAMI Teruo, Study on the Mechanisms of Wear Reduction of Artificial Cartilage through in Situ Observation on Forming Protein Boundary Film, Tribol Online (Web), 10.2474/trol.2.114, 2, 4, 114-119 (J-STAGE), 2007.12. |
| 36. |
S. Yarimitsu, K. Nakashima, Y. Sawae, T. Murakami, In Situ Observation of Forming Boundary Film Composed of Synovia Constituents on Rubbing Surface of Artificial Cartilage Material, Proceeding of International Conference on Advanced Technology in Experimental Mechanics 2007, CD-ROM, 2007.09. |
| 37. |
T. Murakami, Y. Sawae, K. Nakashima, S. Yarimitsu, T. Sato, Micro- and nanoscopic biotribological behaviours in natural synovial joints and artificial joints, PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY, 10.1243/13506501JET245, 221, J3, 237-245, 2007.05, To maintain low friction and low wear in natural synovial joints and joint prostheses with artificial cartilage, adsorbed film formation at micro- and nanoscopic levels appears to play an important role in mixed or boundary lubrication regime where local direct contact occurs. In natural synovial joints, the lubricating gel film is likely to preserve low friction and to protect the bulk cartilage even after the removal of the adsorbed film. For poly (vinyl alcohol) (PVA) hydrogel as artificial cartilage without lubricating gel layer, the adsorbed film is a single protective barrier. In the previous researches on the rubbing pair of PVA against itself or glass plate, the coexistence of albumin (A) and gamma-globulin (G) as A:G = 1 : 2 at total protein concentration of 2.1 wt% in hyaluronate solution showed the lowest wear. In this study, in situ observation of adsorption of proteins was conducted to clarify the dynamic changes in adsorptional behaviours in lubricants containing different protein constituents. In the mixed lubrication regime, the coexistence of albumin and gamma-globulin as A:G = 1:2 showed the lowest friction. The role of appropriate constituents of proteins is discussed on low friction and low wear at micro- and nanoscopic levels on the basis of previous and present results.. |
