Papers - Yazawa, Masaki

Periosteal osteosarcoma with secondary bone marrow involvement

Suehara Yoshiyuki, Yazawa Yasuo, Hitachi Kouhei, Yazawa Masaki

Journal of Orthopaedic Science 9 ( 6 ) 646 - 649 2004.11

ISSN  0949-2658

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<p>Periosteal osteosarcoma is an exceedingly rare type of chondroblastic osteosarcoma, showing a rather good prognosis, and secondary bone marrow involvement is unusual. However, there have been some reports describing periosteal sarcoma involving medullary bone. We encountered a patient, a 38-year-old man, who had a bone surface tumor in the left tibia. An X-ray showed an erosive cortical mass extraosseous portion, located in the diaphysis of the tibia. Other images revealed a thin cortex, periosteal reactions, coarse mineralization in the extraosseous portion, and bone marrow involvement. Grossly, surgical materials showed that the tumor mainly existed at the periosteal portion, only a part of the cortex was destroyed, and there was medullary involvement throughout. Histological examinations showed a predominantly chondroid component with malignant osteoid formation. On the basis of the histological macroscopic and microscopic findings, we made the diagnosis of periosteal osteosarcoma with secondary bone marrow involvement.</p>

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Influence of antiplatelet substances on platelet-rich plasma

Yazawa Masaki, Ogata Hisao, Nakajima Tatsuo, Watanabe Naohide

Journal of Oral and Maxillofacial Surgery 62 ( 6 ) 714 - 718 2004.06

ISSN  0278-2391

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<p>Purpose: Platelets containing a number of growth factors (platelet-derived growth factor [PDGF], transforming growth factor-β [TGF-β], etc) can be obtained in high concentrations through centrifugal separation and are used in clinical applications as platelet-rich plasma (PRP). However, only a few studies have been conducted on the growth factors present in PRP. In this study, we focused on the concentrations of growth factors in PRP and clarified the influence of using antiplatelet substances in the process of platelet concentration to improve the concentration rate of growth factors in PRP. Materials and Methods: We made platelet pellets from whole blood obtained from humans with or without some antiplatelet substances (prostaglandin E ₁, aspirin, apyrase). Platelet pellets were resuspended in phosphate-buffered saline as platelet resuspensions. We measured PDGF and TGF-β1 concentrations in the samples. In measurements, we had the samples treated to release growth factors from platelets to measure accurate concentrations. Results: PDGF and TGF-β1 were concentrated to a mean of over 400% in the samples with antiplatelet substances as compared with the samples without antiplatelet substances. Conclusions: The antiplatelet substances were effective for efficiently concentrating growth factors in platelets. © 2004 American Association of Oral and Maxillofacial Surgeons.</p>

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Basic studies on the bone formation ability by platelet rich plasma in rabbits.

Yazawa Masaki, Ogata Hisao, Kimura Akiko, Nakajima Tatsuo, Mori Taisuke, Watanabe Naohide

The Journal of craniofacial surgery 15 ( 3 ) 439 - 446 2004.05

ISSN  1049-2275

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<p>PURPOSE: Platelets, which contain many growth factors, such as platelet-derived growth factor (PDGF) and transforming growth factor-beta(TGF-beta), can be obtained in high concentrations by centrifugal separation and are being used as platelet-rich plasma (PRP) in clinical applications. The authors evaluated the bone formation ability by PRP in rabbits. MATERIALS AND METHODS: In experiment 1, the authors made platelet precipitations from the whole blood obtained from rabbits. Each precipitated platelet was resuspended in fibrin glue. The glue was applied to a 1-mm wide slit defect of the same rabbit mandible. After 1 week, the authors observed the histologic appearances. In experiment 2, the fibrin glue containing the precipitated platelet was applied to a bicortical defect of a rabbit cranium with beta-tricalcium phosphate (beta-TCP) granules as artificial bone material. After 1 week, 1 month, and 2 months, the authors observed the radiologic and histologic appearances. RESULTS AND CONCLUSIONS: In both experiments, a prosperous bone formation was observed from the beginning more in the group treated with PRP than in the group untreated. In experiment 2, gradual appearances of the bone formation were observed in the bubble of beta-TCP. In application with artificial bone materials, bone formations by PRP were suitably observed.</p>

Expression of bone morphogenetic proteins during mandibular distraction osteogenesis in rabbits

Yazawa Masaki, Kishi Kazuo, Nakajima Hideo, Nakajima Tatsuo

Journal of Oral and Maxillofacial Surgery 61 ( 5 ) 587 - 592 2003.05

ISSN  0278-2391

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<p>Purpose: We examined the expression pattern of bone morphogenetic proteins (BMPs) during mandibular distraction osteogenesis in rabbits and also investigated the mechanism of membranous bone distraction. Materials and Methods: Twenty-three rabbits underwent mandibular distraction (protocol; no latency period, a 1-week distraction at 0.5 mm/d, and a 2-week consolidation period). Samples were collected at 3, 5, and 7 days of distraction and at 1-week and 2-week consolidation. We prepared undecalcified fresh-frozen sections and immunohistochemically evaluated the expression of BMPs 2 through 8. Results: Both endochondral ossification and intramembranous ossification were observed. The expression of BMPs 2, 4, 5, and 6 was observed continuously from the beginning of distraction. BMP-7 was expressed weakly. The expression of BMP-3 was not observed conspicuously during distraction but was strongly expressed at 1- and 2-week consolidation. Conclusion: The expression pattern of BMPs during membranous bone distraction was similar to that during long bone distraction, but it differed from the expression pattern of long bone distraction in that the expression of BMPs was maintained for 2 weeks after the completion of distraction. © 2003 American Association of Oral and Maxillofacial Surgeons.</p>

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Basic studies on the clinical applications of platelet-rich plasma

Yazawa Masaki, Ogata Hisao, Nakajima Tatsuo, Mori Taisuke, Watanabe Naohide, Handa Makoto

Cell Transplantation 12 ( 5 ) 509 - 518 2003

ISSN  0963-6897

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<p>Platelets, which contain many growth factors such as platelet-derived growth factor (PDGF) and transforming growth factor-β (TGF-β), are being used in clinical applications as platelet-rich plasma (PRP). Only a few studies, however, have been conducted on the growth factors present in PRP and on the clinical applications using the drug delivery system (DDS). For the purpose of clinical application, we first modified the PRP preparation method and assessed the amounts of growth factors contained in the human platelet concentrates. Furthermore, we assessed fibrin glue as a DDS of platelet concentrates. Platelet precipitations were made by twice centrifuging human whole blood. The precipitated platelet was resuspended to yield the platelet concentrates. The growth factor concentrations were measured. Fibrin glue sheets containing this platelet concentrate were implanted in rabbit pinna and samples were obtained for immunostaining (anti-PDGF antibody) to assess the use of PRP over time using the fibrin glue as the DDS. The mean concentration of growth factors present in the platelet concentrates was three times or greater than that of conventional PRP. Furthermore, the results indicated that when the platelet concentrate was used with fibrin glue as a carrier, the contents were released over a period of about 1 week. This raises the possibility that this system may be useful in clinical applications.</p>

Surgical creation of a Cupid's bow using W-plasty in patients after cleft lip surgery

Takeshita Ayako, Nakajima Tatsuo, Kaneko Tsuyoshi, Yazawa Masaki, Tamada Ikkei

British Journal of Plastic Surgery 56 ( 4 ) 375 - 379 2003

ISSN  0007-1226

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<p>The three-dimensional contour of the Cupid's bow is extremely important from a cosmetic standpoint, and many patients with bilateral or unilateral cleft lip require revision or reconstruction of the Cupid's bow. A number of surgical techniques have been reported for creating the Cupid's bow, among which the methods of Gillies and Onizuka are the most widely known. In the methods of Gillies and Onizuka, the dog-ear can result in excessive volume in the vermilion notch, raising the trough in the Cupid's bow and leading to regression during the post-surgical period. We have improved upon these techniques using the W-plasty and have obtained satisfactory results that preserve the white skin roll. In our method, the left and right prominence of the Cupid's bow is created through an incision of the white lip, while the central trough is created through a curvilinear incision of the vermilion mucosa. At the two sites of the white lip tissue and the curvilinear incision of the central vermilion tissue, the white skin roll is preserved as much as possible. In patients where the Gillies method had been used, the Cupid's bow tended to be flattened gradually after surgery. We report on the details of our method and the case reports using the technique. © 2003 The British Association of Plastic Surgeons. Published by Elsevier Ltd. All rights reserved.</p>

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光造形モデルと形成外科ネットワークシステム

Kobayashi Masahiro, Fujino Toyomi, Kaneko Tsuyoshi, Takano Junji, Yazawa Masaki, Chiyokura Hiroaki

3次元画像カンファレンス'97講演論文集    114-119 1997.07

Research paper (scientific journal), Joint Work