Browsing by Author "Phimon Atsawasuwan"

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    Decorin modulates collagen matrix assembly and mineralization
    (2009-01-01) Yoshiyuki Mochida; Duenpim Parisuthiman; Suchaya Pornprasertsuk-Damrongsri; Phimon Atsawasuwan; Marnisa Sricholpech; Adele L. Boskey; Mitsuo Yamauchi; The University of North Carolina at Chapel Hill; Thammasat University; Mahidol University; Hospital for Special Surgery - New York
    Decorin (DCN) is one of the major matrix proteoglycans in bone. To investigate the role of DCN in matrix mineralization, the expression of DCN in MC3T3-E1 (MC) cell cultures and the phenotypes of MC-derived clones expressing higher (sense; S-DCN) or lower (antisense; AS-DCN) levels of DCN were characterized. DCN expression was significantly decreased as the mineralized nodules were formed and expanded in vitro. In S-DCN clones, in vitro matrix mineralization was inhibited, whereas in AS-DCN clones, mineralization was accelerated. At the microscopic level, collagen fibers in S-DCN clones were thinner while those of AS-DCN clones were thicker and lacked directionality compared to the controls. At the ultrastructural level, the collagen fibrils in S-DCN clones were markedly thinner, whereas those of AS-DCN clones were larger and irregular in shape. The results from Fourier transform infrared spectroscopy analysis demonstrated that in AS-DCN cultures the mineral content was greater but the crystallinity of mineral was poorer than that of the controls at early stage of mineralization. The in vivo transplantation assay demonstrated that no mineralized matrices were formed in S-DCN transplants, whereas they were readily detected in AS-DCN transplants at 3 weeks of transplantation. The areas of bone-like matrices in AS-DCN transplants were significantly greater than the controls at 3 weeks but became comparable at 5 weeks. The bone-like matrices in AS-DCN transplants exhibited woven bone-like non-lamellar structure while the lamellar bone-like structure was evident in the control transplants. These results suggest that DCN regulates matrix mineralization by modulating collagen assembly. © 2008 Elsevier B.V. All rights reserved.
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    Decorin modulates collagen matrix assembly and mineralization.
    (2009) Suchaya Pornprasertsuk-Damrongsri; Yoshiyuki Mochida; Duenpim Parisuthiman; Phimon Atsawasuwan; Marnisa Sricholpech; Adele L. Boskey; Mitsuo Yamauchi; สุชยา ดำรงค์ศรี
    Decorin (DCN) is one of the major matrix proteoglycans in bone. To investigate the role of DCN in matrix mineralization, the expression of DCN in MC3T3-E1 (MC) cell cultures and the phenotypes of MC-derived clones expressing higher (sense; S-DCN) or lower (antisense; AS-DCN) levels of DCN were characterized. DCN expression was significantly decreased as the mineralized nodules were formed and expanded in vitro. In S-DCN clones, in vitro matrix mineralization was inhibited, whereas in AS-DCN clones, mineralization was accelerated. At the microscopic level, collagen fibers in S-DCN clones were thinner while those of AS-DCN clones were thicker and lacked directionality compared to the controls. At the ultrastructural level, the collagen fibrils in S-DCN clones were markedly thinner, whereas those of AS-DCN clones were larger and irregular in shape. The results from Fourier transform infrared spectroscopy analysis demonstrated that in AS-DCN cultures the mineral content was greater but the crystallinity of mineral was poorer than that of the controls at early stage of mineralization. The in vivo transplantation assay demonstrated that no mineralized matrices were formed in S-DCN transplants, whereas they were readily detected in AS-DCN transplants at 3 weeks of transplantation. The areas of bone-like matrices in AS-DCN transplants were significantly greater than the controls at 3 weeks but became comparable at 5 weeks. The bone-like matrices in AS-DCN transplants exhibited woven bone-like non-lamellar structure while the lamellar bone-like structure was evident in the control transplants. These results suggest that DCN regulates matrix mineralization by modulating collagen assembly.
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    Response of dental pulp cells to Er:YAG irradiation
    (2010-12-01) Arunothai Promklay; Pornpoj Fuangtharnthip; Rudee Surarit; Phimon Atsawasuwan; Tron Hospital; Mahidol University
    Objective: This study aimed to investigate the response of human dental pulp cells lying on a thin dentin disc to Er:YAG irradiation. Background Data: Er:YAG laser irradiation has been effectively used for tooth cavity preparation with minimal damage to the dental pulp tissue. However, study of its direct effect on pulp cells has been limited. Materials and Methods: Primary human dental pulp cells were cultured and allowed to grow on one side of 500-μm-thick dentin discs. An Er:YAG laser at output energies of a 120, 300, or 500mJ/pulse with a repetition rate of 10Hz was used to ablate the non-cell surface of the dentin disc for 10s with cooling irrigation. Results: Twenty-four hours after laser irradiation, light and scanning electron micrographs revealed pulp cells with a normal fibroblastic morphology for the 120 and 300mJ laser-treated groups. In the 500mJ laser-treated group, many pyknotic cells with knob-like projections on the cell surface were mostly observed: the number of cells with normal morphology decreased compared to that of the other groups. However, the production of type I procollagen assessed by the enzyme immunoassay increased in the 500mJ laser-treated group significantly (p<0.001). Conclusion: The low-energy Er:YAG laser (120 and 300mJ at 10Hz) with coolant irrigation did not cause damage to dental pulp cells at critical thickness (500μm) of dentin, whereas the laser of 500mJ at 10Hz induced greater production of type I procollagen with partial damage to the cells. Copyright 2010, Mary Ann Liebert, Inc.
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    Treatment of gingival hyperpigmentation for esthetic purposes by Nd:YAG laser: Report of 4 cases
    (2000-01-01) Phimon Atsawasuwan; Kitiman Greethong; Vanida Nimmanon; Mahidol University
    Gingival hyperpigmentation may cause esthetic problems and embarrassment, especially in patients with a gummy smile. This report presents the use of the Hd:YAG laser for gingival depigmentation. Four cases, 3 females and 1 male, ages between 24 to 28 years old, presented with the same chief complaint of unesthetic gingiva caused by melanin hyperpigmentation. The Nd:YAG laser was set at 6 watts, 60 millijoules per pulse, and 100 pulses per second. The procedures were performed with contact mode in all pigmented areas by using a handpiece with a 320 μm diameter fiber optic. Ablation of the gingival hyperpigmented areas were accomplished without any bleeding complications or significant postoperative pain. Three to 4 weeks after the procedures, the hyperpigmented gingiva appeared healthy, pink, and firm. No recurrence of hyperpigmentation had been found in 11 to 13 months of follow-up. However, in delicate areas such as the marginal gingiva, the Nd-VAG laser should be used cautiously.