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  • 1
    Electronic Resource
    Electronic Resource
    Protective effect of antioxidants against para-nonylphenol-induced inhibition of cell growth in Saccharomyces cerevisiae (2000)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 185 (2000), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The cell growth-modulating activity of an endocrine disruptor, p-nonylphenol (NP), was estimated using the yeast Saccharomyces cerevisiae as a simple model of eukaryotic cells. NP caused a dose-dependent suppressive effect on cell growth of S. cerevisiae at 10, 25 and 50 μM. The NP-induced cell growth inhibition was restored when concomitantly lipophilic antioxidants such as α-tocopherol and β-carotene were supplied, but not the hydrophilic antioxidants ascorbic acid or (−)epigallocatechin gallate (EGCG). The cellular oxygen consumption of S. cerevisiae was also inhibited in a dose-dependent fashion by the extracellular addition of NP, and pretreatment with α-tocopherol and β-carotene suppressed NP-induced inhibition of cellular oxygen consumption, but ascorbic acid and EGCG were not effective. Furthermore, NP caused a marked generation of radical oxygen species (ROS) in S. cerevisiae, which was suppressed by treatment with α-tocopherol and β-carotene, but not with ascorbic acid and EGCG. However, NP did not show a significant inhibitory effect on cell growth and survival of mitochondria-deficient petite mutant cells and they showed a relatively weak ROS-generating activity compared with parent yeast cells. These results suggest that NP-induced inhibition of cell growth and oxygen consumption in S. cerevisiae might be possibly associated with ROS generation in yeast mitochondria. The significance of this finding is discussed from the viewpoint of NP-induced oxidative stress against eukaryotic cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.2000.tb09041.x
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  • 2
    Electronic Resource
    Electronic Resource
    Prevalence of TT virus in patients with fulminant hepatic failure in Japan (1999)
    Springer
    Journal of gastroenterology 34 (1999), S. 589-593 
    Details
    ISSN: 1435-5922
    Keywords: Key words: fulminant hepatic failure ; TT virus ; hepatitis virus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract: A novel virus (TT virus) was isolated from patients with posttransfusion hepatitis of unknown etiology. We studied the prevalence of TT virus in 26 patients with fulminant hepatic failure without risk factors, including blood transfusion, and also examined 106 healthy blood donors as controls. We assayed serum TT virus DNA by seminested polymerase chain reactions and also examined the genotypes of this virus. Serum was obtained at admission from patients with fulminant hepatic failure. Serum samples at admission from seven (27%) of the 26 patients were positive for TT virus DNA. There were no differences in clinical findings, duration from onset to coma, or results of laboratory tests in patients with and without TT virus DNA. However, all 7 patients with TT virus died, whereas 9 of the 19 patients without TT virus died. The outcome for patients with fulminant hepatic failure and TT virus was significantly worse than for patients without the virus (P = 0.0227). TT virus was also detected in 29 (27%) of the 106 healthy blood donors. The genotype of the TT virus was mainly 1a in both groups. There were no differences in the rate of positivity and the genotypes of TT virus between patients with fulminant hepatic failure and healthy blood donors. TT virus infection may not cause severe hepatitis, such as fulminant hepatic failure, but it may indicate a poor outcome in such patients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005350050377
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  • 3
    Electronic Resource
    Electronic Resource
    Promotive action of acylated ascorbate on cellular DNA synthesis and growth at low doses in contrast to inhibitory action at high doses or upon combination with hyperthermia (1996)
    Springer
    Journal of cancer research and clinical oncology 122 (1996), S. 41-44 
    Details
    ISSN: 1432-1335
    Keywords: Ascorbate ; Hyperthermia ; DNA synthesis ; Cell growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Effects of 6-O-palmitoyl ascorbate (ascorbate) developed to increase the antitumour activity of ascorbic acid on DNA synthesis and proliferation of Ehrlich ascites tumour cells were investigated. Treatment of the cells with the acylated ascorbate at 25–50 μM for 1 h resulted in no effect on DNA synthesis, assayed by pulse incorporation of [3H]thymidine after a culture period of 20 h, but led to 49%–87% enhanced DNA synthesis after 4 days, suggesting that long-term culture is required for promotion by ascorbate to occur. At a dose as high as 75 μM acylated ascorbate, however, cellular DNA synthesis was 64% inhibited after 20 h and 99% after 4 days. The results suggest that acylated ascorbate exhibits a dual action on DNA synthesis: promotion at low doses and inhibition at high doses, both of which are potentiated in a time-dependent manner. In contrast to the above-mentioned results at 37°C, acylated ascorbate at 25–75 μM inhibited but did not promote DNA synthesis at 42°C whatever the culture period. Similar results were exhibited when proliferation of cells cultured for a long period was investigated. At 37°C, 50μM acylated ascorbate increased the number of the cells to 3.6 times the control values after 8 days and to 1.9 times after 11 days; in contrast, a 75-μM dose decreased the cell number considerably. Combination with hyperthermia (42°C) suppressed the increase and cell growth was completely inhibited at 75μM.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01203071
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  • 4
    Electronic Resource
    Electronic Resource
    Inhibition of DNA synthesis by methylglyoxal bis(guanylhydrazone) during lymphocyte transformation (1974)
    Springer
    Molecular biology reports 1 (1974), S. 431-436 
    Details
    ISSN: 1573-4978
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The phytohemagglutinin induced DNA synthesis in guinea pig lymph node cells was inhibited remarkably by methylglyoxal bis(guanylhydrazone). This inhibitory effect was dependent on the time of its addition to the lymph node cell culture after stimulation with phytohemagglutinin. If methylglyoxal bis(guanylhydrazone) was added 48 hr after the stimulation, no inhibition of DNA synthesis was observed. Exogenous spermidine added at an early time of cell culture reversed the inhibitory effect of methylglyoxal bis(guanylhydrazone). However, no reversion occurred when spermidine was added at a late time of the cell culture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00360667
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of 1,25-dihydroxyvitamin D3 on induction of scavenger receptor and differentiation of 12-O-tetradecanoylphorbol-13-acetate-treated THP-1 human monocyte like cells (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 165 (1995), S. 547-555 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We investigated the effect of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) on the expression of scavenger receptors in human monocytic cell line (THP-1 cells) treated for 24 h with 12-O-tetradecanoylphorbol-13-acetate (TPA) which induces their differentiation into macrophages. The capacity to degrade 125I-labeled acetyl low density lipoprotein (LDL) was developed in accordance with macrophage differentiation. The treatment with 10 nM 1,25(OH)2D3 for 72 h inhibited the degradation of acetyl LDL by THP-1 macrophages in a dose-dependent manner, suggesting that 1,25(OH)2D3 inhibits scavenging function in macrophages. In order to clarify the mechanism of its inhibitory effect on degradation of acetyl LDL, we performed the ligand binding assay using 125I-labeled acetyl LDL. Scatchard analysis revealed that 1,25(OH)2D3 decreased the number of scavenger receptors without changing the affinity for acetyl LDL. We next examined the effect of 1,25(OH)2D3 on the expression of scavenger receptor mRNA. The mRNA of type I scavenger receptor was first detected in THP-1 cells 4 days after the treatment with TPA, the mRNA level increased up to 6 days, and then decreased. The treatment with 1,25(OH)2D3 for 72 h dramatically decreased the mRNA levels after the acquisition of macrophage phenotypes as evidenced by nonspecific esterase staining. However, 1,25(OH)2D3 did not affect the activity of non-specific esterase nor the induction of interleukin-1β mRNA by lipopolysaccharide in THP-1 macrophages. These findings suggest that 1,25(OH)2D3 exclusively decreases the expression of scavenger receptors in TPA-induced THP-1 macrophages without affecting the basic cellular functions as macrophages. © 1995 Wiley-Liss Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041650313
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  • 6
    Electronic Resource
    Electronic Resource
    Regulation of apoptosis of interleukin 2-dependent mouse T-cell line protein tyrosine phosphorylation and polyamines (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 165 (1995), S. 615-623 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We examined the effect of inhibitors of tyrosine kinase and tyrosine phosphatase on DNA fragmentation, protein tyrosine phosphorylation, and polyamine metabolism in the murine T-cell line CTLL-2. When cells were exposed to herbimycin A, a specific inhibitor of tyrosine kinase (Uehara et al., 1989, Biochem. Biophs. Res. Commun., 163:803-809), in the presence of interleukin 2 (IL-2), DNA was degraded into oligonucleosomal fragments in a dose-dependent fashion. Genistein, another inhibitor of tyrosine kinase (Akiyama et al., 1987, J. Biol. Chem., 262:5592-5596), had similar effects. Exposure of CTLL-2 cells to vanadate, a tyrosine phosphatase inhibitor, blocked with the DNA fragmentation induced by herbimycin A. Tyrosine phosphorylation of 55 Kd protein was inhibited by herbimycin A, and the inhibition was reduced by vanadate. Ornithine decarboxylase (ODC) activity decreased rapidly after herbimycin A was added to CTLL-2 cell cultures, while vanadate increased ODC activity. The exogenous addition of putrescine or spermine, but not that of spermidine, attenuated herbimycin A-induced DNA fragmentation. These findings suggest that phosphorylation of tyrosine residues of 55 Kd protein prevents DNA fragmentation and that polyamines are involved in regulation of apoptosis. © 1995 Wiley-Liss Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041650320
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  • 7
    Electronic Resource
    Electronic Resource
    Role of putrescine in interleukin 1β production in human histiocytic lymphoma cell line U937 (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 147 (1991), S. 199-207 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Treatment with 12-O-tetradecanoyl-phorbol-13-acetate (TPA) and incubation with lipopolysaccharide (LPS) induces Interleukin 1β (IL-1β) production in the histiocytic lymphoma cell line U937. Here we investigated the effect of treatment with both TPA and 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3) on LPS-induced IL-1β production in U937 cells. To clarify the mechanism of IL-1β production, the possible role of polyamines in this process was examined. Combined treatment with TPA and 1,25(OH)2D3 for 72 h followed by incubation with LPS for 24 h caused synergistic induction of both IL-1β release and mRNA expression. On the other hand, TPA increased the numbers of vitamin D3 receptors, which may be one mechanism of this synergistic induction. Ornithine decarboxylase (ODC), a rate-limiting enzyme for polyamine biosynthesis, was also induced by these compounds biphasically: the first peak of ODC activity was observed at 4 h of the incubation with the two compounds and the second peak was at 4 h after the addition of LPS. To find whether these peaks were related to IL-1β production, DL-α-difluoromethylornithine (DFMO), a specific irreversible inhibitor of ODC, was added together with TPA and 1,25(OH)2D3. DFMO decreased the cellular levels of putrescine and spermidine and suppressed IL-1β release and IL-1β mRNA expression by 65%. Exogenous putrescine, but not spermidine, abrogated these kinds of inhibition. Similar results were obtained with DFMO and the polyamines during the differentiation of the cells up to the monocyte or macrophage stage. These results thus suggest that changes in either of these intracellular polyamines, especially putrescine, help to regulate the differentiation of U937 cells, resulting in partial control of the regulation of IL-1β production.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041470203
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