Biomedical subjects

M Sunohara

Publications and source records attributed to M Sunohara.

13 recordsLinked to original sources

PubMed2003

Modulation of human c-mpl gene expression by thrombopoietin through protein kinase C.

The c-Mpl, thrombopoietin (TPO) receptor specificially controls megakaryocytic growth and differentiation. TPO increased the c-mpl promoter activity determined by a transient expression system using a vector containing the luciferase gene as a reporter in the human megakaryoblastic cell line CMK. The maximal promoter activity of c-mpl was obtained 24 hr after pretreatment with TPO for 3 hr and then declined with time. This increase was completely abolished by protein kinase C (PKC) inhibitors (GF109203, calphostin C and H7). Phorbol 12-myristate 13-acetate (PMA) treatment led to an increase in c-mpl promoter activity. These results demonstrate that the promoter activity of c-mpl is modulated by transcription through a PKC-dependent pathway.

Cell Line↗

PubMed2001

Effect of gravity change on the production of thrombopoietic growth factors.

It is reported that the stay in the space develops anemia, thrombocytopenia, and altered function and structure of red blood cell. The mechanism of these abnormalities was not clarified yet. The cloning of the thrombopoietin (TPO), followed by the analysis of TPO and c-mpl (its cellular receptor) knockout mice confirmed its role as the primary regulator of thrombopoiesis. TPO has been shown to stimulate both megakaryocyte colony growth from marrow progenitor cells and the maturation of immature megakaryocyte to form functional platelet. This process includes the massive cytoskeletal rearrangement, such as proplatelet formation and fragmentation of proplatelet. In this study we have focused on the production of thrombopoietic growth factors in mice those were exposed to gravity change by parabolic flight (PF).

Animals↗

PubMed2000

HIV infection of megakaryocytic cell lines.

Thrombocytopenia is a common hematologic disorder in HIV infection and occurs in both asymptomatic and AIDS patients. An autoimmune mechanism has been postulated for the platelet destruction associated with some forms of thrombocytopenia. However, recent studies revealed that megakaryocytes are susceptible to HIV infection and suggested the possibility that HIV can directly impair the platelet production from megakaryocytes. This study was designed to characterize the HIV receptor expression in megakaryocytic cells and the responsiveness to HIV infection. Four different megakaryocytic cell lines at different stages of differentiation were established from the peripheral blood of different individuals with hematologic malignancies. CMK and CMY cells (differentiated cell lines) expressed CD4, but CMS and CTS cells (poorly differentiated cell lines) did not. The HIV coreceptor CXCR4 was also expressed in CMY and CMK cells. HIV-1 (HTLV-IIIB) replicated in CMY cells persistently but not in other three cell lines. CMY cells as well as CMK cells were also susceptible to the lytic infection of HIV-2 (LAV2). Pretreatment of the CMY cells with anti-CD4 antibody inhibited the infection by both HIV-1 and HIV-2. Our results indicate that mature megakaryocytic cells express CD4 along with HIV coreceptors and are susceptible to HIV infection.

CD4 Antigens↗

PubMed1999

Quantitative analysis of extracellular matrix proteins in hypertrophic layers of the mandibular condyle and temporal bone during human fetal development.

A computer image analysis of immunostained extracellular matrix (ECM) proteins (collagen types I, II, III and V, fibronectin and tenascin) in hypertrophic layers in the mandibular condyle and temporal bone of human fetuses, which ranged in gestational age from 12 to 32 weeks, was performed. The percentage of cells positive for proliferating cell nuclear antigen (PCNA) increased in almost the same manner in each region. The level of PCNA was markedly elevated at 16 weeks. The percentage of PCNA-positive cells was low in temporal bone and in the bone-forming layer of the mandibular condyle at 24 weeks. Specific concentration patterns of proteins in the ECM were found at each stage of development. The extent of accumulation of fibrillar collagen and of fibronectin differed, while those of other proteins in the ECM, such as tenascin, osteocalcin and osteonectin, were similar at the two sites.

Bone Density↗

PubMed1999

Distributions of adipocyte, blood vessel, and muscle fiber in human lateral petrygoid muscle during ageing.

The composition of adipocyte, blood vessel, and muscle fiber during ageing from 30 to 90 years of age was examined by a computer analyzing system in human lateral petrygoid muscle. The human lateral petrygoid muscle, the intramuscular connective tissue with adipocyte and blood vessel, displayed a specific change in morphology during ageing. Numerous adipocyte appeared around the blood vessel in the perimysium of the human petrygoid muscle from 60 years of age. The percentage and size of adipocyte and vein per 10,000 micron 2 of the cross sectional area in the muscle increased as well. However, the cross sectional area of muscle fiber was almost constant. The increase of adipocyte was related with changes of blood vessel and connective tissue in the perimysium.

Adipocytes↗

PubMed1999

Comparison between deciduous and permanent incisor teeth in morphology of bovine enamel.

Functional incisor teeth (deciduous and permanent teeth) from Bovidae (14 species) were prepared for scanning electron microscopic observation. Ultrastructural patterns of the enamel layer of deciduous and permanent incisor teeth varied (ex. prisms, arrangement pattern of matrices, and in thickness of enamel layer) in each species. The ultrastructures of prisms in longitudinal sections were classified into three types; A, radial, B, tangential, and C, mix of A and B arrangement enamel; modified Koenigswald's method (1982) in examined species. Type A was found in a large part of permanent and a small part of deciduous incisor teeth, while types B and C were mainly found in the deciduous teeth. These morphological features show the remarkable correlation between permanent and deciduous teeth.

Animals↗

PubMed1998

The endomysium of human embryonic hyoid muscle during development.

A computer analysis was performed on the endomysium of the hyoid muscle in human fetuses, which ranged in gestational week from 12 to 32 weeks. During development of the human hyoid muscle a level of intramuscular connective tissue as reticular fibers displays a specific change in morphology. We examined quantitates and distributions of endomysium in human hyoid muscles from 12 to 32 weeks. The endomysium of the hyoid muscles formed complex structures, and volume rates increased from 20 weeks gestation. On the other hand, the cross sectional area (CSA) of muscle fibers had almost the same profile. The reticular fibers increased during development from 16 to 28 weeks gestation.

Connective Tissue↗

PubMed1998

Immunocytochemical study of the maxilla and maxillary sinus during human fetal development.

We quantitatively examined the distribution of the proliferating cell nuclear antigen (PCNA), which is associated with cell division, and of components of the ECMs (collagen types I and III, tenascin and osteonectin) in the immature zones at three sites: palatine, inferior and vertical surface region of the fetal human maxilla as well as the maxillary sinus (MS) at 12, 16, 20, 24, and 28 weeks gestation. The percentage of PCNA-positive cells was the highest at 16 weeks in the immature zones of maxilla. Tenascin and fibrillar collagens (collagen types I and III) were especially present in the cellular zone linked to the bone and cartilage matrices of the immature zones of the maxillary bone at 20-24 weeks gestation. The osteonectin was detected on the maxillary bone from 24 weeks. These distributions of ECMs revealed the specific and contrasting profiles of development in the human maxillary bone and might reflect the formation of paranasal sinus as MS.

Cell Count↗

PubMed1997

Tonic fiber in Mauremys (Clemmys) japonica jaw muscle.

The jaw muscles of a turtle [Mauremys (Clemmys) japonica (MCJ)], have been analyzed for the histochemical characteristics of their fiber types. Six jaw muscles of the MCJ have been analyzed for histochemical characteristics of their fiber types. In this study, fiber types in two groups of muscles are classified; 1) fast twitch glycolytic (FG), fast twitch oxidative glycolytic (FOG), slow twitch oxidative (SO), and tonic fibers, according to the system of Putnam et al. (1980); 2) reacted differently in similar histochemical tests and classified, respectively, as various types. Especially tonic fibers constituted low percentage in the MAMP (ca., 0.3%), MI (ca., 3.9%) and MPtp (ca., 1.0%) were found. These results suggested that the tonic fiber plays a small part of the function in jaw movement.

Animals↗

PubMed1997

Quantitative morphology of dermal elastic fibers system of the human face during aging.

Human skin has various distributions and arrangements of elastic fiber (EF). Previous reports did not clearly show the distribution of EF in the face skin because of various contents during aging. In this study, a color image analyzer indicated distribution of elastic, oxytalan, and muscle fibers in human face skin. During aging the muscle fiber size and the content of the EF decreased in the modiolus and inferior labial regions of the human skin, and the ratio of the EF was lower than that of oxytalan fiber measured areas. That is, the dimension of oxytalan fiber may reflect the content of EF, and muscle has a role in the distribution of the EF in human face skin. In the deeper regions, small and large EF bundles were found near the sheath of gland and muscles. Therefore, face movement might be an important aspect to maintaining the EF content of human face skin.

Adult↗

PubMed1997

Induction of polyploidization in the human erythroleukemia cell line (HEL) by protein kinase inhibitor (K252a) and the phorbol-ester TPA.

Endomitosis (polyploidization) is a distinctive feature of megakaryocyte differentiation. We examined this mechanism in an erythromegakaryocytic cell line, HEL, using a protein kinase inhibitor K252a or a phorbol-ester TPA. HEL cells treated with K252a showed a marked increase in the proportion of CD41 positive cells and polyploid cells as well as in cellular size and nuclear size. TPA showed similar results but induced multi-nucleation instead of enlargement of nuclear size. K252a added at the G1/S boundary phase did not inhibit the first and second round DNA synthesis, but inhibited cell division. K252a did not inhibit the expression of genes involved in mitosis such as cyclin B, cdc25B and cdc2, in the first round S phase. However, the cyclin B associated Cdc2 kinase activity needed for mitosis during the G2/M phase was reduced by K252a. TPA delayed DNA synthesis and expression of these genes, and suppressed Cdc2 kinase activity in the second round G2/M phase. These results suggest that the polyploidization induced by K252a results from inhibiting mitosis possibly caused by suppression of Cdc2 kinase activity. TPA may induce the multi-nucleation through a different mechanism.

Antigens, CD34↗

PubMed1996

Expression patterns of Raf-1 suggest multiple roles in tooth development.

Raf-1, the product of proto-oncogene c-raf-1, has key roles in the signal transduction pathways within the cell. The molecular mechanisms of tooth development in the mouse embryo are not known in detail. We examined the expression of Raf-1 during subsequent tooth development by immunohistochemical analysis. In mouse embryos at days 12.5 post-coitum (p.c.), Raf-1 was expressed in the dental invaginating epithelium. At p.c. 13.5 (bud stage), Raf-1 was also expressed in the epithelial cells of the enamel organ, but not in the mesenchyme of the dental papilla. We added anti-proliferating cell nuclear antigen (PCNA) antibody as a marker for proliferating cells at early stages of tooth development. At p.c. 12.5 and p.c. 13.5, the staining patterns were very similar to that for Raf-1. At p.c. 15.5 (cap stage), Raf-1 could not be detected. At p.c. 17.5 (bell stage), Raf-1 was expressed in both the odontoblastic and subodontoblastic cells of the dental papilla. However, Raf-1 was not found in the epithelial cells of the enamel organ. We also added anti-type I collagen antibody as a marker for odontoblasts differentiation. The staining pattern for type I collagen antibody as a marker for odontoblasts differentiation. The staining pattern for type I collagen in odontoblasts was almost the same as for Raf-1. The results suggest that Raf-1 may play some roles in both cell proliferation and differentiation at different stages of tooth germ development.

Animals↗

PubMed1983

Comparative study on the mechanical property of silk thread from cocoons of Bombyx mori L.

Specimens of bave (undegummed silk thread) were collected from cocoons of various origins of parent silkworm races, such as Japanese, Chinese, European, Korean and tropical origins, and from as many races as possible. An apparatus was set up to measure the dynamic elastic modulus of these specimens. In all the categories of the races tested, the elastic modulus was linearly related to the size of bave, regardless of the portion of cocoon layer from which the specimens were taken. This correlation was concluded to be universal to the silk thread of Bombyx mori L. species; however, values of the regression coefficient and of the elastic modulus were susceptible to the origin of silkworm races, depending on whether they were native or improved.

Animals↗