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Biomedical subjects

K Masuda

Publications and source records attributed to K Masuda.

At least 685 records · Page 38Linked to original sources
PubMed1983

Possible explanation of radioresistance of glioblastoma in situ.

The response of human glioblastoma to radiation was studied in the logarithmic phase and in the plateau phase of growth, and was compared with those of HeLa S3 irradiated under identical conditions. There was no major difference in the in vitro survival curve parameters between glioblastoma and HeLa in the logarithmic growth phase. However, the surviving fractions for glioblastoma with radiation doses in the range used clinically were higher not only when irradiated in the logarithmic growth phase, but also when subcultured 6 hours after irradiation in the plateau phase, than those for HeLa treated under identical conditions. This suggests that the relatively low cure rate of glioblastoma can be partially explained by the intrinsic radiosensitivity in the logarithmic growth phase and by a high surviving fraction for cells irradiated in the plateau phase.

Cell Survival↗
PubMed1983

Family trees representing the finitely proliferative nature of cultured rat liver cells.

Family trees of rat liver epithelial-like cells in primary culture were obtained by cinemicrographic analysis. With few exceptions the proliferative profiles reconstituted from these family trees showed limited proliferation. This limitation was not due to post-confluence inhibition of proliferation or to nutritional deprivation during time lapse cinemicrography, but to the finite potential of clonal proliferation. In these family trees a cell entered mitosis, incomplete division, death, or a long interphase with no detectable termination. These family trees successfully related the life phases of the individual cells that compose the population to the limited nature of proliferative potential as observed in clonal cell populations.

Animals↗
PubMed1983

C1q and C3bi binding activities of the components of a plasmin-treated human immunoglobulin preparation.

Each of the three major components isolated from a commercial plasmin-treated human immunoglobulin preparation, namely, the plasmin-resistant 7S IgG fraction (PRG), Fab fragment and Fc fragment, was tested before and after heat treatment for binding C1q and fixing C3bi. In unheated state, only PRG was found to bind C1q, whereas none bound C3bi. The binding of C1q by PRG was enhanced by heat treatment which also conferred the activity of binding C3bi to PRG and to Fc fractions, From these results, anticomplementary activity of unheated PRG fraction seems to be due mainly to the complement activation via the classical pathway, whereas the activation by the heat-treated Fc fragment might be via an alternative pathway.

Complement Activating Enzymes↗
PubMed1983

Effects of vasoactive intestinal polypeptide (VIP) and cyclic AMP on isolated dilator pupillae muscle of albino rabbit eye.

The iris dilator muscle strips were dissected from the albino rabbit eye pretreated with 0.5% topical indomethacin and were incubated in a Krebs-Ringer solution. After pretreatment with 3 X 10(-5)M of L-phenylephrine, vasoactive intestinal polypeptide (VIP) was added to the incubation medium at final concentrations ranging from 1 X 10(-10) to 3 X 10(-7)M. The VIP effects on the tension of the dilator muscles and the cyclic AMP (c-AMP) levels in the muscles determined by a radioimmunoassay method were correlated. VIP induced a dose-dependent relaxation of the dilator muscles in the VIP concentration range between 3 X 10(-10) and 3 X 10(-8)M: the ED50 obtained from 21 muscle strips averaged 6.08 +/- 1.34 (mean +/- SEM) X 10(-9)M. The c-AMP level in the dilator muscles increased in a dose-dependent manner in the VIP concentration range from 1 X 10(-9) to 1 X 10(-7)M: the ED50 was computed to be 5.12 X 10(-9)M. The dose-response relationships both for the muscle tension and for the c-AMP level were similar. The time-courses in c-AMP change and muscle relaxation were compared. The c-AMP level increased significantly prior to the onset of muscle relaxation after VIP treatment (10(-7)M), and the level reached a maximum when the muscle relaxation was almost completed. It was concluded that the dilator muscle relaxation by VIP is mediated by an increase in the intracellular c-AMP.

Animals↗
PubMed1983

[Cooperation of radiobiologists and radiotherapists for progress in radiotherapy].

Although studies of radiobiology are expected to contribute to dictate rational optimal modality in radiotherapy and much has been accomplished in the short history of radiobiology, this advances in radiobiology has not caused yet dramatic increase in the cure rate of cancers. Therefore, how a radiobiologist and a radiotherapist had cooperated up to date was reviewed, especially in applying experimental results on the effect of oxygen on the radiosensitivity of mammalian cells to clinical radiotherapy. It was revealed that one of the main reasons for this failure in cooperation is that a radiobiologist and a radiotherapist has their own terminology and has not communicated well using data useful for each other. What to be performed at present and in future were proposed in the field of radiobiology and in the field of radiotherapy.

Animals↗