PubMed Health⌕ Search

Biomedical subjects

M Komaki

Publications and source records attributed to M Komaki.

17 recordsLinked to original sources
PubMed2006

Stem cell properties of human periodontal ligament cells.

BACKGROUND AND OBJECTIVE: Stem cells have been used for regenerative therapies in various fields. The proportion of cells that possess stem cell properties in human periodontal ligament (PDL) cells is not yet well understood. In this study, we quantitatively characterized human PDL cells to clarify their stem cell properties, including self-renewal, multipotency, and stem cell marker expression. MATERIAL AND METHODS: PDL cells were obtained from extracted premolar or wisdom teeth, following which a proliferation assay for self-renewal, a differentiation assay for multipotency, immunostaining for STRO-1, and fluorescence-activated cell sorter (FACS) analysis for stem cell markers (including CD105, CD166, and STRO-1) were performed. RESULTS: Approximately 30% of 400 PDL cells were found to possess replicative potential and formed single-cell colonies, and 30% of these colonies displayed positive staining for STRO-1, 20% differentiated into adipocytes and 30% differentiated into osteoblasts. FACS analysis revealed that PDL cells, including cell populations, expressed the stem cell markers CD105, CD166, and STRO-1. CONCLUSION: The findings of this study indicated that PDL cells possess crucial stem cell properties, such as self-renewal and multipotency, and express the mesenchymal stem cell markers CD105, CD166, and STRO-1 on their cell surface, although there were some variations. Thus, PDL cells can be used for periodontal regenerative procedures.

Adipogenesis↗
PubMed2004

MyoD enhances BMP7-induced osteogenic differentiation of myogenic cell cultures.

The muscle-specific, basic helix-loop-helix transcription factor MyoD can induce cells from other mesenchymal lineages to express a skeletal muscle phenotype. Interestingly, MyoD is initially upregulated in myogenic cells incubated with bone morphogenetic proteins (BMPs), a treatment that induces osteogenic differentiation, suggesting that MyoD has a role in BMP-induced osteogenesis of myogenic cells. This possibility is supported by our observations that muscle satellite cells derived from adult MyoD(-/-) mice show severely impaired osteogenic induction by BMP-7 (osteogenic protein 1; OP-1) as indicated by the decreased gene expression of the bone markers alkaline phosphatase, osteocalcin, Runx2/Cbfa1, and Osterix. Ectopic expression of MyoD increased alkaline phosphatase activity and Osterix mRNA expression in response to BMP treatment. Similarly, ectopic expression of MyoD in the pluripotent mesenchymal cell line C3H10T1/2 increased alkaline phosphatase activity induced by BMP-7. Transcription assays showed that transfection with a MyoD-expression vector, but not other myogenic basic helix-loop-helix transcription factors (Myf5, myogenin) increased Runx2/Cbfa1 transactivation of a reporter gene construct containing either six OSE sequences in tandem or a single OSE site. This effect was enhanced by BMP treatment. These studies, therefore, demonstrate that the muscle transcription factor MyoD is required for efficient BMP-induced osteogenesis of myogenic cells and indicate that MyoD might exert its effects through co-operative interactions with Runx2/Cbfa1.

Alkaline Phosphatase↗
PubMed2004

Dental hygiene education in Japan: present status and future directions.

The aim of this report is to provide basic information about the historical development, current status and future needs of education and training of dental hygienists in Japan. The first formal training of dental hygienists in Japan started at Tokyo in 1949. Restructure and modification of the dental hygiene education system has been reiterated over the years in order to satisfy the needs of the constantly changing society. Although previously only vocational training was provided for dental hygienists, higher-level education has been conducted. The present legislation of dental hygiene has gone through a complicated process. The student should take the dental hygienist licensing examination which is held once a year by the National Board organized by the Ministry of Health, Labour and Welfare. Currently there are 136 dental hygiene schools and the total enrolment is about 7000. The duration of dental hygiene education course has been prolonged from 2 to 3 years since 2001. In 2004, the 4-year course started. The 2-year dental hygiene education program is expected to be replaced with the 3- and 4-year courses by 2010. The dental hygiene education system in Japan will be improved in many ways as dental hygienists are expected to participate in health promotion and preventive care, and to gain knowledge of the economics and organization of health care in relation to oral hygiene.

Certification↗
PubMed2002

Young's interference of electrons in field emission patterns.

We have observed interference fringes of electrons in field emission patterns from multiwalled carbon nanotubes at 60 K. The observed fringe pattern is reproduced by calculations based on the formula of Young's interference of two beams. Three-beam interference has also been detected over short time periods. We discuss the reason why Young's interference appears in the electron emission pattern in accelerating fields.

Journal Article↗
PubMed2001

Muscle satellite cells are multipotential stem cells that exhibit myogenic, osteogenic, and adipogenic differentiation.

Muscle satellite cells are believed to represent a committed stem cell population that is responsible for the postnatal growth and regeneration of skeletal muscle. However, the observation that cultured myoblasts differentiate into osteocytes or adipocytes following treatment with bone morphogenetic proteins (BMPs) or adipogenic inducers, respectively, suggests some degree of plasticity within the mesenchymal lineage. To further investigate this phenomenon, we explore the osteogenic and adipogenic potential of satellite cells isolated from adult mice. Our experiments clearly demonstrate that satellite cell-derived primary myoblasts, expressing myogenic markers such as MyoD, Myf5, Pax7 and desmin, differentiated only into osteocytes or adipocytes following treatment with BMPs or adipogenic inducers, respectively However, satellite cells on isolated muscle fibers cultured in Matrigel readily differentiated into myocytes as well as osteogenic and adipogenic lineages, whereas primary myoblasts did not. Satellite cell-derived primary myoblasts isolated from mice lacking the myogenic transcription factor MyoD (MyoD-/-) differentiate into myocytes poorly in vivo and in vitro (Megeney et al., Genes Dev. 1996; Sabourin et. al, J. Cell Biol., 1999). Therefore, we tested whether MyoD-/- primary myoblasts display increased plasticity relative to wild type cells. Unexpectedly, the osteogenic or adipogenic differentiation potential of MyoD-/- primary myoblasts did not increase compared to wild-type cells. Taken together, these results strongly suggest that muscle satellite cells possess multipotential mesenchymal stem cell activity and are capable of forming osteocytes and adipocytes as well as myocytes.

Adipocytes↗
PubMed2000

Role of MAP kinases p42erk-2/p44erk-1 in cementum-derived attachment-protein-mediated cell attachment.

Cementum-derived attachment protein (CAP) is a collagenous protein which promotes the attachment and spreading of periodontal cell types. We examined the role of the MEK/MAPK pathway in CAP-mediated fibroblast attachment. Human gingival fibroblasts were labeled with 35S-methionine, and the effect of MAP kinase pathway inhibitor PD98059 on attachment and spreading on CAP-coated dishes was examined. Effect on cell proliferation on CAP-coated plates was determined by [3H]-thymidine uptake. Attachment of human gingival fibroblasts to CAP-containing surfaces activated extracellular-signal-regulated kinases (ERK) ERK-2 and ERK-1. In the absence of serum, the ERKs were activated 15 min after attachment, reaching peak levels after 3 hours, and the activity was sustained for at least 12 hours. The enzyme levels were inhibited in cells treated with PD98059. The PD98059 did not significantly affect the kinetics of fibroblast attachment or the number of cells attaching to CAP-coated plates. However, cell spreading was retarded. DNA synthesis as indicated by [3H]-thymidine uptake was not significantly affected. In contrast to PD98059, attachment, spreading, and [3H]-thymidine uptake were inhibited by the protein tyrosine kinase inhibitor genestein. Our results indicate that the MEK/MAPK pathway participates in CAP-mediated fibroblast spreading, but cell attachment and proliferation do not appear to require ERK-2.

Animals↗
PubMed1999

Periodontal-derived cells attach to cementum attachment protein via alpha 5 beta 1 integrin.

A specific collagenous cementum attachment protein (CAP) has been identified in human cementum which promotes selective cell migration towards and attachment of various periodontal derived cell populations to root surfaces in vitro. The CAP is known to support attachment of periodontal-derived cell via an RGD motif, which suggests an integrin-mediated mode of attachment. The purpose of the present study was to ascertain which integrin(s) are involved in the attachment of periodontal-derived cells to CAP. The integrins examined comprised subunits of the major receptors for fibronectin (alpha 5) and collagen (alpha 2, alpha 3), as well as the common beta 1 subunit which is present in many extracellular matrix receptors. The wells of 48-well non-tissue culture treated plates were coated with CAP (2 micrograms/ml). For negative and positive controls the wells were coated with bovine serum albumin and fibronectin (5 micrograms/ml), respectively. Human gingival fibroblasts and periodontal ligament fibroblasts were labeled with [3H]-proline, incubated with anti-integrin antibodies and added to the precoated wells. Attachment was assessed after incubating the cells for 1 h at 37 degrees C in the presence of the antibodies. Antibodies to alpha 5 and beta 1 inhibited the attachment of both human gingival fibroblasts and human periodontal ligament fibroblasts to CAP, while anti alpha 2 and alpha 3 antibodies did not affect the attachment. The binding of the fibroblasts to fibronectin was also inhibited by anti-alpha 5 and beta 1 antibodies, both of which are components of the "classical" fibronectin receptor and remained unaffected by the addition of anti-alpha 2 and alpha 3 antibodies. Proteins migrating in SDS-polyacrylamide gels in positions similar to the alpha 5 and beta 1 integrin subunits were present in fractions bound to a column of CAP coupled to Sepharose CL-4B. These results indicate that the attachment to CAP of the periodontal-derived cells, human gingival fibroblasts and human periodontal ligament fibroblasts, is mediated primarily via the integrin alpha 5 beta 1.

Animals↗
PubMed1997

Bone morphogenetic protein-2 inhibits terminal differentiation of myogenic cells by suppressing the transcriptional activity of MyoD and myogenin.

Bone morphogenetic protein (BMP) is a family of cytokines that induce ectopic bone formation when implanted into muscular tissues. We reported that BMP-2 inhibits the terminal differentiation of C2C12 myoblasts and converts them into osteoblast lineage cells (Katagiri, T., Yamaguchi, A., Komaki, M., Abe, E., Takahashi, N., Ikeda, T., Rosen, V., Wozney, J. M., Fujisawa-Sehara, A., and Suda, T. (1994) J. Cell Biol. 127, 1755-1766). In the present study, we examined the molecular mechanism of the inhibitory effect of BMP-2 on terminal differentiation of myogenic cells. When either MyoD or myogenin cDNA was introduced into C3H10T1/2 (10T1/2) cells with a muscle-specific CAT reporter containing four copies of the right E-box of muscle creatine kinase (MCK) enhancer, the CAT activity was dose-dependently suppressed by BMP-2. Furthermore, BMP-2 inhibited the terminal differentiation of these subclonal 10T1/2 cells that stably expressed MyoD or myogenin into mature myotubes that expressed myosin heavy chain and troponin T. The differentiation of a subclone of the MyoD-transfected NIH3T3 cells into mature muscle cells was also inhibited by BMP-2. BMP-2 induced alkaline phosphatase activity in 10T1/2-derived, but not in NIH3T3-derived MyoD-transfected cells. These cells constitutively expressed exogenous MyoD and myogenin, which were localized exclusively in the nuclei irrespective of the presence and the absence of BMP-2. However, these cells failed to express the mRNAs of endogenous myogenic factors and MCK when cultured with BMP-2. In the electrophoresis mobility shift assay using nuclear extracts of the myogenic cells, MyoD and myogenin bound to the right E-box in the enhancer region of the MCK gene even in the presence of BMP-2. These results suggest that BMP-2 inhibits the terminal differentiation of myogenic cells by suppressing the transcriptional activity of the myogenic factors.

3T3 Cells↗
PubMed1996

Bone morphogenetic protein-12 and -13 inhibit terminal differentiation of myoblasts, but do not induce their differentiation into osteoblasts.

Effects of bone morphogenetic protein (BMP)-12 and BMP-13, new members of the BMP family which belong to the transforming growth factor (TGF)-beta superfamily, on terminal differentiation of myoblasts were examined in C2C12 and L-6 myoblasts. When the myoblasts were cultured with BMP-12 or BMP-13, the expression of the myosin heavy chain and the formation of multinucleated myotubes mRNA in L-6 cells. The inhibitory effects of BMP-12 and BMP-13 on myogenic differentiation were similar to the effects of BMP-2, though their potencies were lower than BMP-2. Unlike BMP-2, neither BMP-12 nor BMP-13 induced alkaline phosphatase activity in C2C12 myoblasts. The differences in the biological activities of these new BMPs suggest that the intracellular signalling pathway used by BMP-12 and BMP-13 differs from that of BMP-2.

Alkaline Phosphatase↗
PubMed1996

Bone morphogenetic protein-2 does not alter the differentiation pathway of committed progenitors of osteoblasts and chondroblasts.

Bone morphogenetic proteins (BMPs) induce cartilage and bone formation at both bony and non-bony sites. We examined the possibility whether BMP-2 induces differentiation of osteoblast progenitors into chondroblast lineage cells using organ culture and cell culture prepared from the calvaria of newborn mouse. BMP-2 stimulated alkaline phosphatase activity (a marker of osteoblasts) and induced positive alcian blue staining (a marker of chondroblasts) in a dose- and time-dependent manner in cell cultures isolated from the whole calvaria. BMP-2 also increased the number of round-shaped cells in the cell cultures, which expressed type II collagen. Histologically, the calvaria consisted of not only bone, but also cartilaginous tissues stained with alcian blue, which were located along the endocranial surface of the parietal and occipital bones. When the calvariae were organ-cultured in the presence of BMP-2, the territory of the cartilaginous tissue was markedly increased, and covered most of the occipital bone. A histological examination of the cultured calvariae showed that the bony region of the occipital bone remained unchanged, while the cartilaginous region expanded independent of the bony region. BMP-2 increased the number of proliferating chondroblasts only in the cartilaginous tissue, but never induced new cartilage formation at the bony site. We obtained cells from the anterior portion that contained no cartilage and the posterior portion which contained cartilage, and we subsequently cultured them separately. BMP-2 stimulated ALP activity in all the cultures. However, the treatment with BMP-2 increased the intensity of alcian blue staining only in tissue culture of the posterior portion, but never induced alcian blue staining in tissue culture of the anterior portion. These results indicate that the chondrocytes induced by BMP-2 were derived from the cartilaginous tissue, which had already formed at the surface of the calvarial bone. BMP-2 did not induce differentiation of committed osteoblast progenitors into chondroblast lineage cells.

Alkaline Phosphatase↗
PubMed1994

Bone morphogenetic protein-2 converts the differentiation pathway of C2C12 myoblasts into the osteoblast lineage.

The implantation of bone morphogenetic protein (BMP) into muscular tissues induces ectopic bone formation at the site of implantation. To investigate the mechanism underlying this process, we examined whether recombinant bone morphogenetic protein-2 (BMP-2) converts the differentiation pathway of the clonal myoblastic cell line, C2C12, into that of osteoblast lineage. Incubating the cells with 300 ng/ml of BMP-2 for 6 d almost completely inhibited the formation of the multinucleated myotubes expressing troponin T and myosin heavy chain, and induced the appearance of numerous alkaline phosphatase (ALP)-positive cells. BMP-2 dose dependently induced ALP activity, parathyroid hormone (PTH)-dependent 3',5'-cAMP production, and osteocalcin production at concentrations above 100 ng/ml. The concentration of BMP-2 required to induce these osteoblastic phenotypes was the same as that required to almost completely inhibit myotube formation. Incubating primary muscle cells with 300 ng/ml of BMP-2 for 6 d also inhibited myotube formation, whereas induced ALP activity and osteocalcin production. Incubation with 300 ng/ml of BMP-2 suppressed the expression of mRNA for muscle creatine kinase within 6 h, whereas it induced mRNA expression for ALP, PTH/PTH-related protein (PTHrP) receptors, and osteocalcin within 24-48 h. BMP-2 completely inhibited the expression of myogenin mRNA by day 3. By day 3, BMP-2 also inhibited the expression of MyoD mRNA, but it was transiently stimulated 12 h after exposure to BMP-2. Expression of Id-1 mRNA was greatly stimulated by BMP-2. When C2C12 cells pretreated with BMP-2 for 6 d were transferred to a colony assay system in the absence of BMP-2, more than 84% of the colonies generated became troponin T-positive and ALP activity disappeared. TGF-beta 1 also inhibited myotube formation in C2C12 cells, and suppressed the expression of myogenin and MyoD mRNAs without inducing that of Id-1 mRNA. However, no osteoblastic phenotype was induced by TGF-beta 1 in C2C12 cells. TGF-beta 1 potentiated the inhibitory effect of BMP-2 on myotube formation, whereas TGF-beta 1 reduced ALP activity and osteocalcin production induced by BMP-2 in C2C12 cells. These results indicate that BMP-2 specifically converts the differentiation pathway of C2C12 myoblasts into that of osteoblast lineage cells, but that the conversion is not heritable.

Alkaline Phosphatase↗
PubMed1992

Primary adult T-cell lymphoma of the breast.

A case of primary adult T-cell lymphoma (ATL) of the breast is described. A 69-year-old woman presented with a painless, rapidly growing lump in her left breast. Staging procedures demonstrated no sign of generalized disease. Following a Patey's mastectomy, 10 courses of adjuvant chemotherapy (CHOP) were successfully administered. The light microscopic, immunohistochemical and molecular genetic analyses of the surgical specimen revealed a primary ATL. Seropositive mothers who breast-feed their children may facilitate the accumulation of T cells carrying HTLV-I in their breasts and thereby increase their risks of developing breast ATL.

Aged↗
PubMed1989

Monostotic fibrous dysplasia with involvement of the mandibular canal.

A 72-year-old woman sought treatment with a rare monostotic fibrous dysplasia occurring in the mandible and involving the mandibular canal. Her chief complaint was swelling, which had appeared about 2 years previously, had enlarged gradually, and was associated with spontaneous pain. X-ray film examination revealed a ground-glass opaque image of blurred demarcation, and 99mTc-methylene diphosphonate bone scintigraphy disclosed an area of marked radioisotope uptake. Histopathologic examination revealed the area of bone marrow and spongy bone to be replaced by fibrous tissue, irregular beam-shaped woven bone, and lamellar bone. Contouring of the expanded portion of the bone and surgical decompression of the mandibular canal were performed with good results.

Aged↗