Biomedical Research
Online ISSN : 1880-313X
Print ISSN : 0388-6107
ISSN-L : 0388-6107
6 巻 , 2 号
選択された号の論文の8件中1~8を表示しています
Full Papers
  • KATSUTOSHI YOSHIZATO, TOSHIO TAIRA, NOBORU YAMAMOTO
    1985 年 6 巻 2 号 p. 61-71
    発行日: 1985/04/01
    公開日: 2017/03/22
    ジャーナル フリー

    Experiments with fibroblasts in culture demonstrated that collagen fibrilsstrongly inhibited DNA synthesis, and suppressed cell growth. Collagen fibrils also induced a specific cell shape with abundant cytoplasmic protrusions. The rate of DNA synthesis on collagen was less than 20% of that on tissue culture plastic. The extent of the suppression of DNA synthesis was strictly dependent upon the quantity of collagen available to cells. 60 pg/cell, which differed from that for the induction of a collagen-mediated change in the cell shape (5.3 ng/cell). The extent of suppression of DNA synthesis on collagen fibrils decreased as the length of culture period increased, suggesting that fibroblasts interact with collagen during culture and induce changes in the properties of collagen. Native collagen which loses ability to form a fibril in the culture condition was prepared by modifying ε-amino groups of lysyl residues. The chemically modified collagen didnot induce any collagen-mediated changes in fibroblasts, indicating the importance of a polymeric form of collagen for collagen to cell interaction.

  • MAKOTO ARAKI, AKIO TAKAGI, TAKEHISA FUJITA, TOSHIMITSU MATSUBARA
    1985 年 6 巻 2 号 p. 73-78
    発行日: 1985/04/01
    公開日: 2017/03/22
    ジャーナル フリー

    Using skinned muscle fibers, the response to caffeine was compared between malignant hyperthermia susceptible (MHS) and control swines. The caffeine concentration for the threshold and halfmaximum contracture was markedly lower in MHS swines than in controls. These results agree with those in human malignant hyperthermia (MH). Dantrolene did not exhibit any effect on the dose-response relationship ofcaffeine contracture in the skinned fiber from MHS swines. The muscle fiber diameter was significantly increased in every fiber type of MHS swines. The pathogenesis of porcine MH and effect of dantrolene were discussed.

  • KYOKO KOISHI, HIROMI FURUICHI, TOSHIO OHBAYASHI, YOSHIKI OHBA
    1985 年 6 巻 2 号 p. 79-85
    発行日: 1985/04/01
    公開日: 2017/03/22
    ジャーナル フリー

    Increase in tetraploid nuclei in relation to age was analyzed based on sedimentaion profiles of liver nuclei labeled with [3H]thymidine in vivo. On centrifugation, nuclei synthesizing DNA sedimented faster than theresting nuclei. Among the nuclei from rats of 3 weeks old, most of the labeled nuclei became diploid again, but in rats of 4 weeks old half of the labeled nuclei remained tetraploid. During week 5, the tetraploid nuclei were formed from diploid nuclei; these tetraploid nuclei did not show the ability to synthesize DNA yet. However, no further conversion of diploid to tetraploid cells occurred during week 6, whereas the percentage of cells with tetraploid nuclei was still increasing. Therefore, a definitive change in nuclear segregation after DNA replication seems to occur during weeks 4 and 5 after birth.

  • YASUAKI AOKI, NOBUTAKA WAKAMIYA, TAKAHIRO OCHI, SHIGEHARU UEDA, SHIRO ...
    1985 年 6 巻 2 号 p. 87-91
    発行日: 1985/04/01
    公開日: 2017/03/22
    ジャーナル フリー

    Procainamide (PA), an anti-arrhythmic agent, was recently found to be a specific inhibitor of suppressor T cells. The effects of PA and X-ray irradiation were studied on both plaque forming cells (PFC) and antibody titer using sheep red blood cells and vaccinia virus as antigens. A single injection of PA (50μg) augmented both PFC and antibody titer; the increase was more than twice that seen after X-ray irradiation. A single injection of higher doses and repeated PA injections did not further augment antibody production. These data indicate that PA could be introduced as the sensitizing step in some experimental antibody-dependent anticancer regimens.

  • KENJI SOBUE, TOSHIHIKO TANAKA, KEIKO KANDA, KATSUHITO TAKAHASHI, KAZUY ...
    1985 年 6 巻 2 号 p. 93-102
    発行日: 1985/04/01
    公開日: 2017/03/22
    ジャーナル フリー

    Actomyosin isolated from the bovine adrenal medulla was capable of Ca2+-dependent superprecipitation, and retained the actin-stimulated Mg2+-ATPase activity. A half maximum activation was attained with Ca2+ at about 4 μM. The superprecipitation was inhibited by agents interacting with calmodulin, i.e. trifluoperazine, chlorpromazine, W-7 and promethazine with I50 values of 15, 70, 85 and 440 μM, respectively, suggesting the involvement of calmodulin in the Ca2+-dependent actin-myosin interaction in medullary actomyosin. About 8-10 mg of myosin was obtained from 200 mg of medullary actomyosin isolated from 100g of the bovine adrenal medulla. Caldesmons (caldesmon150 and caldesmon77), actin-linked regulatory proteins, were identified in our actomyosin preparation by immunoblotting using anti-gizzard caldesmon IgG. The medullary actinmyosin interaction was inhibited by caldesmons in a dose-dependent manner. Myosin light chain kinase, a myosin-linked regulatory protein, was also identified in our medullary actomyosin preparation by immunoblotting. Actin-stimulated Mg2+-ATPase activity of medullary myosin was enhanced 2.5-fold when the myosin light chain was phosphorylated in the presence of Ca2+ and calmodulin. We suggest that the actin-myosin interaction in medullary actomyosin is dually regulated by Ca2+ via the actin-linked and myosin-linked systems.

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