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H Sakiyama

Publications and source records attributed to H Sakiyama.

50 records · Page 3Linked to original sources
PubMed1986

Inhibition of X-ray or chemical carcinogen-induced neoplastic transformation of C3H10T1/2 fibroblasts by lipopolysaccharides.

Oncogenic transformation of mouse 10T 1/2 fibroblasts induced upon exposure to X-ray or N-methyl-N'-nitro-N-nitrosoguanidine was suppressed if lipopolysaccharide (LPS) was present in the culture medium. The suppressive effect of LPS was exerted within 24 h after irradiation. Suppression was dependent on the concentration of LPS added and LPS (2 micrograms/ml) derived from Salmonella minnesota R595 reduced the number of transformed type III foci per dish from 0.39 to 0.15. Indomethacin (1 to 30 microM) further enhanced the effect of LPS in a dose-dependent manner.

Animals↗
PubMed1984

Phagocytosis and solubilization of fixed cells by metastatic hamster embryo fibroblasts, Nil2C2.

When Nil2C2, a metastatic clone derived from hamster embryo fibroblasts (Nil), was inoculated over [3H]leucine-labeled fixed cells, Nil2C2 cells solubilized and phagocytosed fixed cells, and the radioactivity was released into the culture medium as trichloroacetic acid-soluble fragments. The solubilization of fixed cells was dependent on both the time of incubation of living cells with fixed cells and the number of living cells inoculated. Nil2C2 cells were shown by autoradiographic and electron microscopic studies to peel off fixed cells and ingest them as large fragments. The solubilization of fixed cells was significantly decreased when plasminogen was depleted from the culture medium. Protease inhibitors such as leupeptin, epsilon-aminocaproic acid, and soybean trypsin inhibitor partially inhibited the proteolysis and phagocytosis of Nil2C2 cells. Mouse peritoneal macrophages activated by Salmonella typhimurium solubilized fixed cells after the addition of 12-O-tetradecanoylphorbol-13-acetate. However, they did not phagocytose fixed cells as large fragments.

Animals↗
PubMed1981

Absence of gamma-actin expression in the mouse fibroblast cell line, L.

Cytoplasmic isoactins of mouse fibroblast L-cells were examined by two-dimensional gel electrophoresis. In contrast to other cultured cell lines, which contain both beta- and gamma-actin, L-cells contained only beta-actin species. This unique phenomenon was due neither to the transformed status of this cell line nor to the characteristic nature of adipose tissue fibroblasts of C3H mice. When RNA of L-cells was translated in a nuclease-treated reticulocyte lysate system, actin synthesized in vitro also appeared as only one species, beta-actin. Therefore, the genetic information for gamma-actin is absent at the level of translatable mRNA in L-cells.

Actins↗
PubMed1980

Transfer of radioactive materials from radioactively labeled conditioned medium to fixed cells.

Transfer of radioactive materials to glutaraldehyde-fixed Ni12Cl cells was observed when fixed cells were incubated in conditioned media of Ni12Cl cells cultured with various radioactive precursors such as glucosamine, fucose or leucine. Radioactivities were not transferred to fixed cells when the conditioned medium was boiled. The transfer decreased drastically by treatments of the medium with trypsin or detergents (dodecylsulfate or deoxycholate). Efficient transfer occurred only at the physiological temperature. No radioactivity was transferred to fixed cells if conditioned media of nonlabeled cells and radioactive precursors including various nucleotide sugars were incubated with fixed cells. The transferring activity in a conditioned medium did not decrease by the dialysis or the centrifugation at 105,000 x g for 2 h, and remained in the supernatant. The activity migrated into the sucrose gradient. Materials transferred to fixed cells were not solubilized by detergents but were released by the treatment with trypsin, indicating transferred materials were covalently associated with fixed cells. Those results suggest that conditioned media thus obtained contain both substrate(s) and enzyme(s) which fixed labels to fixed cells.

Animals↗
PubMed1979

Cellular interaction between fixed and living cells. Transfer of radioactive materials from living cells to fixed cells.

Transfer of radioactive materials to fixed cells from an overlying layer of living cells has been examined to determine whether fixed cells can act as acceptors of glycosyltransferases of living cells. After the incubation of living cells were removed by EDTA treatment, and the radioactivity associated with the fixed cells was determined. Lipids, proteins and carbohydrates were found to be transfered from the living cells to the fixed cells. The amount of radioactivity transferred to the fixed cells was dependent on the number of both fixed and living cells and increased with the time of incubation. When fixed cells were treated with chloroform-methanol before the addition of living cells, the transfer of both lipids and proteins to the fixed cells decreased drastically, but only a slight decrease incarbohydrate transfer was observed. Most of the radioactive materials transferred from living cells labeled with glucosamine or fucose to chloroform-methanol-treated fixed cells were solubilized by trypsin but not by the detergents tested. Approximately 55% of the materials transferred from the cells labeled with glucosamine could be solubilized by hyaluronidase and chondroitinase, and the rest was solubilized by neuraminidase and a glycosidase mixture. The treatment of chloroform-methanol-extracted fixed cells with trypsin caused a significant decrease in the transfer from cells labeled with glucosamine. When nucleotide sugars were used as the radioactive precursor, no significant amount of radioactivity was transferred to the fixed cells.

Autoradiography↗
PubMed1975

The synthesis of Forssman glycolipid in clones of nil 2 hamsters fibroblasts grown in monolayer or spinner culture.

The amount of Forssman glycolipid (GL-5) was investigated in two clones of Nil hamster cells grown either in monolayer or in spinner culture. GL-5 assayed by the complement-fixation inhibition test increased with increasing cell density in the monolayer. However, cells grown in spinner cultures failed to show the density-dependent response in both clones examined. Cells transformed by hamster sarcoma virus did not show the density-dependent increase of GL-5, even in cells grown in monolayer. The effect of transfer from confluent to sparse cultures on the amount and the synthesis of GL-5 was also examined. It is suggested that the GL-5 that accumulates in cells during confluency is diluted into the daughter cells and that the decrease of the Forssman lipid does not precede cell division.

Animals↗
PubMed1972

Glycolipid synthesis in normal and virus-transformed hamster cell lines.

Studies have been continued on the synthesis of glycolipids by the NIL 2 line of hamster cells. Several clones were isolated from this line. These clones vary in morphology, saturation density, and glycolipid composition. Contrary to expectation there was no correlation between saturation density and complexity of the glycolipid pattern. In fact, the clone with the highest saturation density was the only one to show the complete set of glycolipids found previously in NIL 2 cells. All untransformed NIL clones show an increase in the level of "higher" (more than two saccharides/ceramide) glycolipids as the cells approach confluence. In the line containing all three "higher" neutral glycolipids, all three increased as cells approached saturation density. In the line containing only hematoside, this compound increased at confluence. Cells transformed by hamster sarcoma virus or polyoma virus showed no density-dependent glycolipid synthesis.

Animals↗