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Biomedical subjects

M Shimoyama

Publications and source records attributed to M Shimoyama.

At least 19 recordsLinked to original sources
PubMed1979

Effect of blood, ascites, and tumor cell density on cytocidal action of neocarzinostatin.

Cytocidal activity of Neocarzinostatin (NCS) was analyzed in vitro by using cultured and ascitic L1210 cells. NCS shows rapid and typical concentration-dependent cytocidal action against L1210 cells. The concentration required for 90% cell-kill (MLD90) and for all 10(6) cell-kill (MIC/10(6)) was 5 x 10(-2) and 4 x 10(-1) microgram/ml, respectively, when L1210/C cells were exposed to NCS at the concentration of 2 x 10(5)/ml in RPMI-1640 medium. When L1210/C cells at the concentration of 1.3 x 10(7)/ml were exposed to NCS, cytocidal activity of NCS decreased, and MLD90 and MIC/10(6) increased to 1.75 x 10(-1) microgram/ml (3.4x) and 2.83 microgram/ml (6.5x), respectively. Also, when a small fraction of whole BDF1 mouse blood, red blood cells, or spleen cells was present in the reaction mixture, cytocidal activity of NCS appeared to decrease. Furthermore, when washed hemorrhagic ascitic L1210 cell suspension was exposed to NCS, 100 times or more concentration of NCS was required for 90% cell-kill or all 10(6) cell-kill. The effect of plasma or serum on cytocidal activity of NCS was minimum. These results indicate that cytocidal activity of NCS is greatly inhibited through contact with tumor cells, blood cells, spleen cells, and/or hemorrhagic ascites. This may be one of the reasons why L1210 cells, which show high sensitivity against NCS in vitro, are less sensitive in vivo. In order to explain these findings, the possibility of inactivation of NCS by the cells or reduction of free active NCS molecules by the binding or adsorption with the cells is discussed. This characteristics in action of NCS should be take into account in clinical use.

Animals↗
PubMed1979

Mg2+-dependent adenosine triphosphatase as an enzyme histochemical marker for the lymphomas of B-cell origin.

Twenty-nine cases of malignant lymphoma were studied by the enzyme histochemical method and membrane surface markers. Strong adenosine triphosphatase (ATPase) activity was demonstrated in 15 cases of 20 B lymphomas and in one case of null-cell lymphoma (1/1) by a light- and electron-microscopic enzyme histochemical method according to Wachstein et al. Neoplastic cells in nodules of 2 nodular lymphomas (0/2) and in 8 cases of T lymphomas (0/8) did not show any ATPase activity enzyme-histochemically. The ATPase activity of B lymphomas was electron-microscopically demonstrated on the plasma membrane of lymphoma cells but not in the cytoplasmic organelles. The specificity of ATPase activity in B lymphomas was also examined enzyme-histochemically with reference to normal lymphoid tissues. Such specificity was similar to that of non-neoplastic B lymphocytes of primary follicles and the mantle zone of secondary follicles in lymphoid tissues. Therefore, ATPase is one of the useful enzyme histochemical markers in differentiating T and B subclasses of malignant lymphomas.

Adenosine Triphosphatases↗
PubMed1978

Ca2+/protein modulator-dependent and -independent cyclic GMP phosphodiesterase from hog heart.

Ca2+/protein modulator-dependent and -independent guanosine 3':5'-monophosphate (cGMP) phosphodiesterases were separated from hog heart. The protein modulator-free Ca2+/protein modulator-dependent enzyme was partially purified by repeated DEAE-cellulose column chromatography and heat treatment. The final preparation of this enzyme showed no significant basal activity under the standard assay conditions. Lineweaver-Burk plots of the Ca2+/protein modulator-dependent enzyme activity indicated the presence of only a single kinetic form of the enzyme with Km=2.0 X 10(-6) M for for cGMP, whereas the plots for the independent enzyme were anomalous, showing both high and low K m values for cGMP. The Ca2+/protein modulator-dependent enzyme proved relatively stable at 48 degrees C for 1 h, but the independent form lost its activity under the same conditions. Furthermore, 50% inhibition of the dependent enzyme activity, but only 10% inhibition of the independent enzyme activity, was observed with 0.1 mM adenosine 3':5'-monophosphate (cAMP) when 1 muM cGMP was employed as a substrate.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1978

Possible participation of glucocorticoid in elevation of 3',5'-cyclic AMP levels through inhibition of cyclic AMP phosphodiesterase.

Administration of prednisolone and cholate to rats elevated levels of cAMP (adenosine 3',5'-cyclic monophosphate) by 1.5- to 2.0-fold. Compounds such as prednisolone, hydrocortisone, cholate, and deoxycholate were found to be potent inhibitors of partially purified cAMP phosphodiesterase prepared from rat liver. Kinetic analysis showed that the prednisolone inhibition was noncompetitive with a Ki of 8.9 x 10(-4) M. These results suggest that in addition to increasing DNA-dependent RNA polymerase activity in vivo, a large application of glucocorticoid may incur elevation of intracellular cAMP levels.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1978

Leukemic distribution of a human acute lymphocytic leukemia cell line (Ichikawa strain) in nude mice conditioned with whole-body irradiation.

Induction of leukemia in nude mice (BALB/c nu/nu) was attempted by inoculation with a human acute lymphocytic leukemia cell line (Ichikawa strain, maintained in an ascitic form in our institute). Inoculation of the cells i.v. in normal nude mice failed to produce leukemia. However, conditioning with whole-body irradiation (500 rads) resulted in induction of leukemia after i.v. inoculation, especially when such inocluation was performed 3 days after irradiation. The correlation of survival to inoculum size (10(5) to 10(5)) was inversely exponential. Leukemic infiltration was noted in the spleen, lymph nodes, bone marrow, meninges, liver, kidneys, etc., as seen in human leukemia. These cells retained their original cytological characteristics, ultrastructural features, and surface markers and revealed high terminal deoxynucleotidyltransferase activity as T-derived cells. Chromosome analysis revealed aneuploidy in a hypotetraploid range with a mode of 88 chromosomes.

Animals↗