Search PubMed⌕ Search

Biomedical subjects

Y Sokawa

Publications and source records attributed to Y Sokawa.

At least 55 records · Page 3Linked to original sources
PubMed1990

Changes of intrahepatic localization of hepatitis B core antigen in HBeAg positive patients with chronic active hepatitis B treated with interferon.

The intrahepatic distribution of hepatitis B core antigen (HBcAg) was studied in 14 HBeAg-positive patients with chronic active hepatitis B who were treated with interferon. Patients received 5 to 6 million units daily of human lymphoblastoid interferon or human diploid fibroblast interferon for 28 days. Intrahepatic HBcAg was detected by the indirect immunoperoxidase technique. Before interferon therapy, the intrahepatic HBcAg was detected almost equally in both the nucleus and cytoplasm. The expression of nuclear HBcAg decreased significantly (p less than 0.001) after interferon therapy, irrespective of the outcome for DNA polymerase and/or HBeAg/anti-HBe status. The expression of cytoplasmic HBcAg decreased significantly (p less than 0.05) only in the patients who lost DNA polymerase after treatment, whereas it increased in patients with DNA polymerase and/or HBeAg in the serum. These findings suggested that a shift of intrahepatic HBcAg from the nucleus to the cytoplasm occurred in HBeAg-positive patients with chronic active hepatitis B receiving interferon therapy.

Adult↗
PubMed1989

Elevated levels of 2',5'-oligoadenylate synthetase activity in peripheral blood mononuclear cells and serum during acute exacerbation of chronic hepatitis B.

We measured 2',5'-oligoadenylate synthetase activity in peripheral blood mononuclear cells and serum of 14 HBsAg- and HBeAg-positive patients with chronic hepatitis B with or without acute exacerbation. Elevated levels of 2',5'-oligoadenylate synthetase in peripheral blood mononuclear cells and serum were found in seven chronic hepatitis B patients with acute exacerbation, whereas in the remaining seven chronic hepatitis B patients without acute exacerbation, both levels were similar to those of normal subjects despite active hepatitis B virus multiplication. 2',5'-Oligoadenylate synthetase levels in peripheral blood mononuclear cells and serum, which were not statistically different from those of normal subjects prior to acute exacerbation, increased during acute exacerbation from 3- to 23-fold over initial levels following elevations in ALT activity. 2',5'-Oligoadenylate synthetase levels fluctuated over a normal range while ALT levels were elevated, and they returned to a baseline with ALT normalization. This suggests that the in vivo interferon system may be activated during acute exacerbation, and that this activation may not be a result of hepatitis B virus multiplication alone, but also of a host-immune response to hepatitis B virus multiplication. Three patients were treated with interferon during acute exacerbation. All three had elevated levels of 2',5'-oligoadenylate synthetase in peripheral blood mononuclear cells and serum just before treatment. 2',5'-Oligoadenylate synthetase levels increased only 1.1- to 2.2-fold over initial levels during treatment, with none of the patients clearing HBeAg during and after treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

2',5'-Oligoadenylate Synthetase↗
PubMed1989

Decreased interferon binding capacity of peripheral blood mononuclear cells during interferon treatment of chronic hepatitis B with special reference to (2'-5') oligoadenylate synthetase activity.

The levels of (2'-5') oligoadenylate synthetase (2-5 AS) activity and interferon (IFN) binding capacity were measured in peripheral blood mononuclear cells (PBMC) obtained from 9 patients with chronic hepatitis B (CHB) during IFN treatment. Six of the patients received human lymphoblastoid IFN (HLBI) or IFN-beta daily for 4 weeks at doses of 6 million units (MU); of the remaining three, 2 were treated on alternate days at doses of 3 MU for 5 weeks, and the other given daily IFN doses of 3 MU for 4 weeks. IFN binding was measured using HLBI (2 X 10(8) IU/mg protein) and completely purified 125I-labeled HLBI (290 Ci/mmol specific activity). The levels of 2-5 AS activity in PBMC were measured using radioimmunoassay. Before IFN treatment, the levels of IFN binding capacity were similar to those of normal subjects. During treatment, however, IFN binding capacity decreased significantly from 40 to 60% of initial levels 1 to 2 weeks after the start of treatment in the 7 patients receiving daily IFN, while in the remaining 2 patients given IFN on alternate days, IFN binding capacity did not decrease during treatment. On the other hand, 2-5 AS activity in PBMC increased during IFN treatment in all patients. Even after IFN binding capacity decreased in the 7 patients, the levels of 2-5 AS activity remained high during the remainder of treatment. These finding suggest that some mechanism other than IFN binding capacity may be responsible for the determination of 2-5 AS levels.

2',5'-Oligoadenylate Synthetase↗
PubMed1988

Induction of (2'-5')oligoadenylate synthetase in serum-starved HeLa S3 cells by growth factors and its role in growth regulation.

When serum-starved HeLa S3 cells were stimulated to proliferate by addition of fetal calf serum (FCS), (2'-5')oligoadenylate synthetase (2-5A synthetase) activity was induced. Although no interferon (IFN) activity was detectable in the HeLa S3 cell-conditioned culture medium after growth stimulation, addition of anti-IFN-beta monoclonal antibody inhibited both the expression of the 2-5A synthetase gene and the production of the enzyme, suggesting that endogenous IFN-beta was involved in 2-5A synthetase induction. Purified preparations of three growth factors, epidermal growth factor, platelet-derived growth factor, and insulin, also induced 2-5A synthetase through IFN-beta. When serum-starved HeLa S3 cells were treated with FCS, DNA synthesis was initiated synchronously, with peaks after 12 and 32 h, although the level of 2-5A synthetase reached a maximum after the first peak of DNA synthesis. Inhibition of 2-5A synthetase induction by anti-IFN-beta antibody enhanced the second, but not the first cycle of DNA synthesis. These results suggested that in HeLa S3 cells, after stimulation with growth factors the IFN/2-5A synthetase system played a role in cell growth negative regulatory mechanisms.

2',5'-Oligoadenylate Synthetase↗
PubMed1988

Characterization of L1210 S cells with low sensitivity to mouse interferon-gamma.

A mouse leukemic cell line L1210 Sg with a low sensitivity to interferon-gamma (IFN-gamma) was described. On the nature of the antiviral action and binding of IFN, L1210 Sg cells were compared with L1210 m cell line which is sensitive to IFN-gamma. For a half reduction of the vesicular stomatitis virus-RNA synthesis, L1210 Sg cells required 500-fold more IFN-gamma than L1210 m cells did. However, both cell lines were induced to the antiviral state to the same extent with IFN-alpha or -beta. L1210 Sg and L1210 m cells were sensitive to the anti-proliferative action of IFN-alpha and -beta, but insensitive to IFN-gamma. (2'-5')Oligoadenylate synthetase was induced in these cell lines by IFN-beta, but not by IFN-gamma, which suggests that the induction of this synthetase may not be responsible for the antiviral action of IFN-gamma. No substantial difference between L1210 Sg and L1210 m cells was found in IFN receptors for IFN-gamma and IFN-beta either in number per cell or in their affinity to corresponding IFN type. However, differences were noted in time course profiles of cell-associated IFN-gamma at 37 C: in L1210 m cells, a rise-and-decay profile of IFN-gamma bound to cells was observed at 37 C, but in L1210 Sg cells, rise and slight decay was observed. On the other hand, a similar rise-and-decay curve of IFN-beta bound to these cells was observed. These results indicated that the low sensitivity of L1210 Sg cells to IFN-gamma may be due to this slight decay of receptor-bound IFN-gamma.

Animals↗
PubMed1986

Undermethylation of interferon-gamma gene in human T cell lines and normal T lymphocytes.

The relative levels of DNA methylation at CCGG sequences within and around the interferon-gamma (IFN-gamma) gene in normal human tissues and cell lines were examined by Southern blot analysis using isoschizomeric restriction enzymes, HpaII and MspI. On the test of normal tissues, the IFN-gamma gene was undermethylated only in a small population of T lymphocyte, whereas the gene was fully methylated in T cell-depleted lymphocytes and uterus cells. In TCL-Fuj cell line which is a T cell line producing a high level of IFN-gamma spontaneously, the IFN-gamma gene was undermethylated. Moreover, the extent of DNA methylation was inversely correlated to the level of expression of the IFN-gamma gene in several T cell lines including sublines derived from TCL-Fuj cells. However, partial or complete unmethylation at the CCGG sites of IFN-gamma gene was observed in a promyelocytic leukemia cell line and two epithelial cell lines that fail to produce IFN-gamma irrespective of induction. These results suggest that undermethylation of IFN-gamma gene is necessary but not sufficient for its efficient expression.

Cell Line↗
PubMed1986

(2'-5') oligoadenylate synthetase in chicken embryo erythrocytes and immature red blood cells.

The appearance and induction of (2'-5')oligoadenylate synthetase (2-5A synthetase) in chicken embryo erythrocytes during development, and the activity and molecular size of this enzyme in immature red blood cells from anemic chickens were studied. Enzyme activity first appeared in the embryos on the 15th day of incubation, a marked increase being seen 1 or 2 days after hatching. In erythrocytes from early embryos without 2-5A synthetase activity, chicken interferon (5 IU/ml at most) induced the production of a large amount of the enzyme. In immature red blood cells from anemic chickens, only a small amount of 2-5A synthetase was detected in the nuclear fraction. The cytoplasmic fraction contained the smaller enzyme (about 45 kilodaltons), but the larger enzyme (85-120 kilodaltons) was scarcely detected in either fraction. The larger enzyme may be synthesized during the maturation of red blood cells.

2',5'-Oligoadenylate Synthetase↗
PubMed1986

Structure and expression of a cloned cDNA for human (2'-5')oligoadenylate synthetase.

17S poly(A)+RNA, which hybridized to an oligonucleotide complementary to a part of the partial cDNA (E1cDNA) (Merlin et al. (1983) Proc. Natl. Acad. Sci. U.S. 80, 4904) for 2-5A synthetase, was isolated from interferon-treated human KB cells and used for cDNA cloning. Several overlapping cDNAs were cloned by using the oligonucleotide as a probe. Two of them were joined at their overlapping region, resulting in a cDNA (22-1 cDNA) of 1.4 kb containing a long open reading frame. When the cDNA was expressed in COS-7 cells with an eukaryotic promoter, active 2-5A synthetase was produced and localized mainly in the cytoplasm. The 5'-proximal ATG in 22-1 cDNA is followed immediately by another ATG. This second ATG was assumed to work as the initiator codon. If so, this enzyme comprises 363 amino acids.

2',5'-Oligoadenylate Synthetase↗
PubMed1986

Induction of human interferon-gamma mRNA analyzed by cytoplasmic dot hybridization: effect of Con A, TPA, and A23187.

The cytoplasmic dot hybridization method was improved by eliminating non-specific false signals. The non-specific binding to a probe disappeared almost completely when the hybridized nitrocellulose sheet was treated with pronase. Using this improved method we demonstrated that reagents such as 12-O-tetradecanoylphorbol-13-acetate (TPA), concanavalin A (Con A) and a calcium ionophore (A23187) could induce the expression of IFN-gamma gene of a human T-lymphoblastoid cell line, TCL-Fuj 2M, where TPA functioned synergistically with Con A and A23187. However, when the cells were cultured with the ionophore for more than one day the amount of IFN-gamma mRNA was markedly reduced to a low level.

Calcimycin↗
PubMed1984

Constitutive production of human interferons by mouse cells with bovine papillomavirus as a vector.

Mouse C127I cells were transformed with a chimeric plasmid consisting of bovine papillomavirus and human interferon (HuIFN) gene (either IFN-gamma or IFN-alpha 5) placed under the control of simian virus 40 early promoter. The transformed cells retained 30-50 copies each of the hybrid plasmid extrachromosomally and secreted a high level of HuIFNs constitutively up to 3-4 X 10(5) international units/ml. The secreted HuIFN-gamma had no detectable activity on mouse cells, whereas HuIFN-alpha 5 was slightly active on mouse cells. Each IFN was neutralized either by anti-HuIFN-gamma or anti-HuIFN-alpha antiserum. The partially purified 35S-labeled HuIFN-gamma produced by the transformed cells showed heterogeneous bands with apparent Mrs of 22,000-25,000 on NaDodSO4/polyacrylamide gel electrophoresis. This value is similar to that of natural IFN-gamma and larger than the molecular weight calculated from the amino acid sequence, which suggests that HuIFN-gamma secreted by transformed mouse cells was glycosylated. The 35S-labeled IFN-alpha 5, immunoprecipitated with anti-HuIFN-alpha antiserum from the supernatant of the transformed cells, had a molecular weight of mature protein. These results suggest that the bovine papillomavirus vector can be used to produce a large quantity of foreign proteins in mammalian cells.

Animals↗
PubMed1984

Immunological cross-reactivity between large and small (2'-5')oligoadenylate synthetases from pig cells.

Using glycerol gradient centrifugation, the molecular sizes of porcine (2'-5')oligoadenylate synthetases (2-5A synthetases) were estimated. The 2-5A synthetase purified from pig spleen was about 150 kDa, while the enzyme extracted from nuclei of Newcastle disease virus-infected pig epithelial cells (SK-h) was about 20-40 kDa. The nuclear 2-5A synthetase was selectively adsorbed to Protein A-Sepharose beads conjugated with anti-spleen 2-5A synthetase antibody. Thus, the smaller 2-5A synthetase in nuclei of pig cells shares a protein structure with the larger enzyme from pig spleen.

2',5'-Oligoadenylate Synthetase↗
PubMed1984

Presence of (2'-5')oligoadenylate synthetase in avian erythrocytes.

(2'-5')Oligoadenylate synthetase (2-5A synthetase) was found in avian erythrocyte lysates from chicken, goose, and pigeon, with high levels being observed in chicken erythrocytes. No activities, however, were detected in erythrocytes from human, sheep, mouse, turtle, frog, trout, or lamprey. In chicken erythrocyte lysate, about 70% of ATP was converted to 2-5A molecules during a 20-h incubation, in which the tri- and tetra-adenylate were the major products. The tri-, tetra-, penta-, and hepta-adenylate were synthesized sequentially, but the levels of the di-adenylate were low throughout the reaction. 2-5A synthetase was also seen in erythrocytes from specific pathogen-free chickens, suggesting that the enzyme was not produced as a result of microbial infections. 2-5A synthetases from avian erythrocytes of chicken and pigeon were found not only in cytoplasms, but also in nuclei. No enzyme activity, however, was detected in the nuclear fraction of goose erythrocytes. The molecular size of 2-5A synthetase in nuclei from chicken erythrocytes was 45,000-60,000 daltons, while cytoplasms contained an 85,000- to 120,000-dalton enzyme. In addition, the synthetase was present in several types of chicken tissue including liver, intestine, bone marrow, spleen, bursa, pancreas, and thymus, but not in brain, heart, or stomach.

2',5'-Oligoadenylate Synthetase↗
PubMed1983

Structure and expression of a cloned cDNA for mouse interferon-beta.

A unique sequence in the mouse genome which cross-hybridized to a cloned human interferon-beta 1 gene was detected by DNA blot analysis. Taking advantage of this, a cDNA library prepared from partially purified mRNA for mouse interferon-beta was screened using human interferon-beta 1 DNA as a probe. One of the positive clones, pM beta-3, contained a 680-base pair cDNA insert, whose base sequence contained a single large open reading frame for 182 amino acids. The coding sequences of the cDNA showed homologies of 63% at the nucleotide and 48% at the amino acid level with respect to human interferon-beta 1 cDNA (Taniguchi, T., Ohno, S., Fujii-Kuriyama, Y., and Muramatsu, M. (1980) Gene 10, 11-15). The first 21 amino acids, considered to be the signal peptide, were followed by 24 amino acids, whose sequence was identical with the NH2-terminal sequence that had been reported for mouse interferon-beta from Ehrlich ascites tumor cells (Taira, H., Broeze, R. J., Jayaram, B. M., Lengyel, P., Hunkapiller, M. W., and Hood, L. E. (1980) Science (Wash. D.C.) 207, 528-530). The complete primary sequence of mature interferon-beta polypeptide consisting of 161 amino acids (Mr = 19,700) was deduced. There are three N-glycosylation sites, and this offers an explanation for the larger molecular size (Mr = 26,000-40,000) of natural mouse interferon-beta in comparison to the deduced interferon polypeptide. The cDNA, when fused to a SV40 promoter sequence and then introduced into COS-7 cells, directed the synthesis and secretion of a protein product indistinguishable from the authentic mouse interferon-beta.

Amino Acid Sequence↗