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  • Cell & Developmental Biology  (7)
  • Acid-labile α-interferon  (1)
  • Analytical Chemistry and Spectroscopy  (1)
  • 1
    ISSN: 1573-2592
    Keywords: Acid-labile α-interferon ; human T-cell leukemia/lymphoma virus I ; Epstein-Barr virus ; systemic lupus erythematosus ; acquired immune deficiency syndrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract B-cell lines were established as spontaneous outgrowths of cell cultures from patients with adult T-cell leukemia (ATL). Three such lines were shown to have integrated human T-cell leukemia/lymphoma virus 1 (HTLV-I) proviral sequences as well as Epstein-Barr virus (EBV) infection. Supernatant fluids from these cultured cells were assayed for interferon (IFN) production. Acid-stable α-IFN was found to be produced by one cell line (CF), and acid-labile α-IFN by the other two (HS, MJB). In contrast, HTLV-I-infected T-cell lines did not produce IFN. Some EBV-infected B-cell lines produce acid-labile α-IFN, while others do not. Since α-IFN, both acid stable and acid labile, is found in sera from patients with the polyclonal activation of B cells as a constitutive part of the disease, the above observations suggest a possible role of polyclonal B-cell activation in α-IFN production in these diseases.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cytoplasmic extracts of green monkey kidney-Vero M3 cells that have been grown to high cell density and have entered the stationary phase of growth lose the capacity to synthesize proteins after they have been frozen and thawed. The same loss of protein synthetic capacity is not observed when cytoplasmic extracts of low cell density Vero M3 or HeLa S-3 cells are frozen and thawed before assay, nor when high cell density Vero M3 cell extract is assayed without having been frozen. The loss of the protein synthesis capacity of the frozen and thawed extracts of stationary phase Vero M3 cells is accounted for by the appearance of an inhibitor. The inhibitor is precipitated in the 30 to 70% ammonium sulfate fraction of the 100,000 g supernatant. It is inactivated by heat and is non-dialyzable. It blocks the transfer of amino acids from tRNA to growing peptide chains.The amount of this inhibitor in the extract (measured by relative inhibition of in vitro protein synthesis) increases as a function of the density of the cells from which the extract was made, and the increase can be correlated with the progressive turnoff of protein synthesis in whole cells.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Peptide production in senescent and presenescent human foreskin fibroblasts was measured using 2-dimensional polyacrylamide gel electrophoresis. This procedure permits the visualization of a cohort of the major peptides being produced. Among this cohort of over 500 peptides only two were found to differ in relative amount in that more was being produced in senescent cells. This difference was confirmed by measurements of the relative intensity of the peptide spot. This difference was senescent cell-specific and not due to the differences in rate of growth of senescent and non-senescent cells.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 90 (1977), S. 307-320 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: When Vero cells, a line derived from an African Green Monkey kidney, are grown under conditions where the saturation density is limited by serum, they deplete the growth medium of a factor necessary for cell division. The factor is a component of serum. When Vero cells are plated at low density (2 × 104/cm2) in this depleted growth medium (after dialysis against serum-free Dulbecco's Modified Eagle's Medium) they initiate an unbalanced program of growth. Protein synthesis proceeds at the same rate as parallel cells in fresh serum, and the cells accumulate protein as a function of time. DNA synthesis is also initiated in these cells, and the amount of DNA per cell increases for the next four days after plating. However the cells quickly stop dividing. Measurements of DNA per cell using microspectrofluorometry show that the cells are accumulating in the late S and G2 period during this time. Thus we conclude that these cells cannot pass through a transition point in G2. When fresh serum is added to cells after three days in depleted growth medium, they divide before they begin to synthesize DNA. This further confirms that they are in late S and G2. Cell division is promoted in Vero cells in depleted growth medium by bovine fetuin, and to a lesser extent by bovine albumin. Cell division is not promoted by insulin, hydrocortisone, dexamethasone, linolenic acid, calcium, and trypsin inhibitor from ovomucoid. From these data we conclude that transit through G2 requires the presence of an extracellular factor.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 92 (1977), S. 293-301 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Protein synthesis and degradation were studied throughout a growth cycle of Vero cells. The rate of protein synthesis, measured as the rate of amino acid incorporation, reached a maximum at the mid-exponential phase and declined to 10-30% of the maximum in the stationary phase. The rate of protein degradation, measured as the release of radioactive amino acids from uniformly labelled cellular proteins, did not vary in the growth cycle. The amount of protein per cell, measured by an isotopic method, remained constant when normalized to account for the variation in the proportion of actively dividing cells in the cell population during the growth cycle. Cellular protein was determined using this method since it was found that the chemical determination of the amount of protein in the monolayer was not accurate during the early stage of the growth cycle. This was due to a significant amount of serum protein adsorbed to the cells. In this study we were able to show that, in Vero cells, protein synthetic activity is correlated with the rate of cell division, and variations in the rate of synthesis alone are sufficient to meet the changing requirements for cellular protein in a growth cycle.
    Additional Material: 3 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 103 (1980), S. 467-474 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cell line B16/C3 will undergo melanogenesis at a specific time after plating. We have found that this time can be modulated by varying the pH of the culture medium. At high pH levels (8.2-8.6) the onset of melanogenesis occurs in 3 or 4 days, while at lower pH (6.7-7.2) it occurs in 7 or 8 days. Furthermore, the time of onset is also sensitive to the extracellular ionic strength. The addition of sodium lactate, sodium chloride, or any other salt tested delays or blocks completely the onset of melanogenesis. These effects are not simply consequence of growth inhibition, nor can they be correlated with patterns of lactate accumulation.These cells are sensitive to pH or ionic strength after entering the stationary phase just prior to the time of onset of melanogenesis. The existence of a specific pH-and ionic-strength-sensitive phase may provide an important clue to the events responsbile for differentiation in this system.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 114 (1983), S. 68-72 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The mouse melanoma cell line B16/C3 offers an excellent in vitro model for studying melanocyte differentiation. Melanogenesis can be induced by serum, a hormone-supplemented serum-free medium, melanocyte stimulating hormone, and dibutyryl cAMP. The tumor promoter, 12-O-tetradecanoyl-phorbol-13-acetate, 5-bromodeoxyuridine, and acidic pH inhibit this process. Using two-dimensional polyacrylamide gel electrophoresis, we have identified four cellular proteins whose production is modulated during melanogenesis, a process which includes concomitant increases in levels of ty-rosinase, the rate limiting enzyme for melanin biosynthesis, melanization, and ultimately, cell death. The production of these proteins are coordinately expressed or inhibited in response to the diverse inducers and inhibitors of melanogenesis. We conclude from these studies that these specific proteins are intimately involved in the differentiation of B16/C3 melanoma cells.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Vero M3 cells, a line derived from the kidney of an African Green Monkey, display certain alterations in their protein synthetic apparatus as a function of time during a growth cycle. (Growth cycle here refers to exponential growth of unsynchronized cells in culture and their subsequent passage into the stationary phase.) The capacity of cytoplasmic extracts of these cells to promote endogeneous mRNA-mediated polypeptide synthesis or poly U-mediated polyphenylalanine synthesis declines from the second day after the initiation of the growth cycle. The ribosome sedimentation profile indicates that after the second day of growth a decrease also occurs in the total amount of ribosomes per cell, and that a shift occurs from predominantly polyribosome structures to predominantly subunits and monoribosomes structures. The activity of the translation factor, elongation factor 1, also progressively decreases after the second day of growth. Furthermore, when crude factor preparations from cells in the second day of growth (Exponential phase) and from cells in the fifth day of growth (Stationary phase) are compared for leucyl-tRNA synthetase and prolyl-tRNA synthetase activities, it is found that the extracts from fifth-day cells have significantly less activity. The activity of another enzyme, acid phosphatase, remains relatively unaffected as a function of time during the cell growth cycle. When HeLa S3 plating cells are grown under the same conditions, they do not display the same responses.
    Additional Material: 7 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 24 (1989), S. 733-736 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The liquid SIMS mass spectra of silver acetate dissolved in a glycerol matrix is discussed, with emphasis on the formation of a ‘silver mirror’ on the surface of the glycerol droplet owing to reduction of the silver acetate. Silver clusters containing up to three silver atoms have been observed from this mirrored surface; Ag3+ cluster ions are not observed in the spectrum when conditions are such that the mirror is not formed. For example, use of a slightly oxidizing matrix (o-nitrophenyl octyl ether or m-nitrobenzylalcohol) prevents formation of the ‘mirror’; only Ag+ is sputtered from this surface.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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