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Biomedical subjects

T Kuwata

Publications and source records attributed to T Kuwata.

At least 163 records · Page 9Linked to original sources
PubMed1979

Suppressive effects of interferon on syncytium formation by RD-114 virus in human transformed cells.

The RD-114 virus rapidly induced syncytia in the human transformed cell lines, RSa, RSb and IFr. Treatment of the virus with heat or ultrasonic vibration completely eliminated the syncytium-forming activity. Irradiation with u.v.-light or treatment with beta-propiolactone (BPL) reduced but did not completely destroy the activity. Pre-treatment of the cells for 16 h with 25 to 500 units/ml of human leucocyte interferon (Le-IF) or fibroblast interferon (F-IF) significantly reduced formation of syncytia by active virus or inactivated (u.v. or BPL) virus. This activity of interferon was inhibited by treatment of the cells with cycloheximide. Interferon did not increase the binding of 3H-uridine-labelled RD-114 virus to the cells. It is postulated that interferon treatment altered the plasma membrane of the cells and thus reduced their capacity to fuse.

Cell Fusion↗
PubMed1979

Comparison of the suppression of cell and virus growth in transformed human cells of leukocyte and fibroblast interferon.

The effects of human leukocyte interferon (Le-IF) and fibroblast interferon (F-IF) on the growth of the transformed human cell lines, RSa and RSb, were compared. Both were considerably more sensitive to F-IF than to Le-IF. Two cell lines, IFr and F-IFr, derived from the RSa cell line, were resistant to the anticellular effects of Le-IF, but less resistant to those of F-IF.

Cell Division↗
PubMed1979

Effect of cholera toxin on the antiviral and anticellular activities of human leukocyte interferon.

Cholera toxin added into cell cultures together with human leukocyte interferon inhibited the establishment of the antiviral state by interferon but not the anticellular activity of interferon in human cells. Sensitivities of various human cell lines to anticellular activities of interferon and cholera toxin were compared, but no direct correlation between both activities were demonstrated. These results suggest that antiviral and anticellular activities of interferon are due to different mechanism of actions, and cholera toxin does not act directly on the receptor site for interferon.

Cell Division↗
PubMed1978

Detection of Mason-Pfizer monkey virus infection by syncytia formation of human cells doubly transformed by Rous sarcoma virus and simian virus 40.

Human cells doubly transformed by Rous sarcoma virus and SV40 (RSb cells) formed syncytia by cocultivation with Mason-Pfizer monkey virus (MPMV)-producing cells. This cell fusion was blocked by anti-MPMV serum indicating that the phenomenon is MPMV specific. The RSb cells were successfully used for MPMV infectivity assay in the same manner as KC cells.

Antibodies, Viral↗
PubMed1978

Inhibition of DNA synthesis and alteration of cyclic adenosine 3',5'-monophosphate levels in RSa cells by human leukocyte interferon.

Human leukocyte interferon inhibits the proliferation of the virus-transformed human embryonic cells RSa. Incorporation of [3H]thymidine (TdR) into an intracellular pool and the activity of TdR kinase were reduced in the interferon-treated RSa cell culture. High-degree (90%) inhibition of [3H]TdR incorporation was associated with concentrations of added interferon that produced more than a twofold increase in the intracellular cyclic AMP (cAMP) level, and low-degree inhibition was associated with smaller increases in cAMP. In the IFr cell culture, which is relatively resistant to the anticellular action of interferon, considerably less inhibition of TdR incorporation and a slight increase in cAMP were observed. Extracellularly added dibutyryl-cAMP inhibited the proliferation of both RSa and IFr cells to almost the same degree. A decrease in cAMP level and the initiation of DNA synthesis of G1-phase-arrested RSa cells by serum addition were prevented when cells were pretreated with interferon. These results indicated that intracellular cAMP may mediate the inhibitory effect of interferon on DNA synthesis and cell growth.

Avian Sarcoma Viruses↗
PubMed1978

Suppression of murine leukaemia virus production by ouabain and interferon in mouse cells.

Ouabain markedly inhibited the growth of the mouse cell lines K3b and JLS-V9 and the production of murine leukaemia virus (MuLV) in them. The inhibition of MuLV production was abolished by exposing the cells to normal medium or by adding a high concentration (43 mM) of K+ ions to the ouabain-containing medium. MuLV production was reduced by ouabain more rapidly than host cell directed protein synthesis. After treatment of cells with ouabain (0.5 mM) for 7 h, extracellular reverse transcriptase reverse transcriptase activities were reduced by 87 to 92%. However, the intracellular level of polymerase activities remained almost unchanged (77 to 98% relative to the control). Mouse interferon inhibited the production of MuLV in K3b cells and this antiviral action was not blocked by 0.5 mM-ouabain.

Animals↗
PubMed1977

Inhibition of DNA synthesis of synchronized RSa cells by human leukocyte interferon.

A human leukocyte interferon preparation suppressed DNA synthesis and subsequent mitosis of synchronously growing virus-transformed human RSa cells. DNA synthesis was inhibited completely when interferon was added to cell cultures in late G1 phase, but was not so inhibited when interferon was added in G1/S boundary phase. Overall protein synthesis was reduced only slightly by interferon treatment. The findings suggested that critical events leading to the inhibition of DNA synthesis and subsequent mitosis by interferon action take place in late G1 phase or S phase.

Cell Division↗
PubMed1977

Effects of ouabain on the anticellular and antiviral activities of human and mouse interferon.

When transformed human embryonic cells, RSa and RSb, were treated for 48 h with both 10(-7) M-ouabain and 1000 units/ml of human leucocyte inteferon, there was an additive suppression of cell growth. In contrast, the antiviral action of the human interferon was inhibited by this concentration of ouabain. Similar effects of combined treatment with interferon and ouabain were found with IFr cells (which are relatively resistant to the anticellular effect of interferon), and with mouse cells of the K3b line.

Animals↗
PubMed1977

Effects of cycloheximide and puromycin on the antiviral and anticellular activities of human interferon.

Human leucocyte interferon has antiviral activity and anticellular effects on the transformed human cell lines, RSa and RSb. Treatment of the cells with cycloheximide or puromycin at 0-5 to 5-0 microgram/ml suppressed the antiviral action of interferon but increased its anticellular effects. Interferon also has antiviral activity in IFr cells, but this is relatively resistant to its anticellular action. Nevertheless, both drugs suppressed the antiviral activity of interferon and increased its anticellular action.

Cell Division↗
PubMed1976

Characteristics of a human cell line successively transformed by Rous sarcoma virus and simian virus 40.

Human enbryo cells were successively transformed by the Schmidt-Ruppin strain of Rous sarcoma virus (SR-RSV) and simian virus 40 (SV40) in vitro, and the double transformant HuE 13 RS was established. From this cell line the two clonal cell lines RSa and RSb were isolated. In both, presence of SV40 T antigens was demonstrated by the fluorescent antibody technique, and the presence of RSV genomes was verified in one RSb clone by focus formation after fusion with chick embryo cells. Growth of these cells was affected by dibutyryl cAMP without marked morphologic changes. Cells were extremely sensitive to the anticellular action of human leukocyte interferon.

Antigens, Viral↗
PubMed1976

Effects of interferon on the human clonal cell line, RSa: inhibition of macromolecular synthesis.

Multiplication of the human clonal cell line, RSa, is completely inhibited by human leukocyte interferon preparations. Synthesis of DNA and protein is markedly reduced in these cells in proportion to the concentration of interferon applied. Interferon treatment leads to accumulation of cells of an epithelial morphology which do not enter the division cycle. It is suggested that the growth inhibitory effects of interferon on RSa cells may result from these effects.

Cell Division↗
PubMed1976

Concanavalin A agglutinability of a temperature-sensitive mutant of Rous sarcoma virus.

Concanavalin A (Con A) concentration dependence of agglutinability of a mutant of Rous sarcoma virus which is temperature-sensitive for transformation was examined. Con A agglutinability of the virion was quantitatively expressed by measuring radioactivities of 60 to 70 S RNA extracted from Con A-agglutinated material. The mutant grown at a permissive temperature (35 degrees C) agglutinated at a significantly lower concentration of Con A, compared with that at a non-permissive temperature (40 degrees C).

Agglutination↗
PubMed1976

Effects of adriamycin on the reverse transcriptase and the production of murine leukemia virus.

Adriamycin inhibited the endogenous RNA-, poly (A)-d(T)12-, and calf thymus DNA-catalyzed reaction of reverse transcriptase from AKR mouse murine leukemia virus (AKR-MLV). This inhibition was found at the reaction levels of endogenous RNA-directed and subsequent DNA-directed DNA synthesis. Although adriamycin and actinomycin D significantly reduced the growth of AKR mouse cells (K3b), the treatment with adriamycin could bot inhibit the AKR-MLV production in these cells. Actinomycin D inhibited AKR-MLV production completely in the same experimental condition. In adriamycin-resistant K3b/Am cells, which were isolated by intermittent treatment of K3b cells with adriamycin, persistence of AKR-MLV was demonstrated. K3b/Am cells showed some altered characteristics such as reduced growth rate and tumorigenicity.

Animals↗