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  • Artikel  (40)
  • Life and Medical Sciences  (40)
  • 1985-1989  (40)
  • 1
    Digitale Medien
    Digitale Medien
    Spontaneous fusion between metastatic mammary tumor subpopulations (1988)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 36 (1988), S. 129-136 
    Details
    ISSN: 0730-2312
    Schlagwort(e): hybrid cells ; metastasis ; heterogeneity ; generation of aneuploidy ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: This study describes a differential frequency of spontaneous fusion between metastatic and nonmetastatic subpopulations derived from a single mouse mammary tumor. Subpopulations 66, 66cl4 (a variant of 66 which is resistant to both thioguanine and ouabain), 410.4, and 44FTO (a thioguanine-resistant, ouabain-resistant derivative of 410.4) spontaneously metastasize from subcutaneous and mammary fatpad sites. Subpopulations 168, 168FARO (a diaminopurine-resistant, ouabain-resistant derivative of 168), 67, 68H, and 410 do not. The ability of these subpopulation lines to fuse spontaneously in vitro was determined after coculturing a drug-resistant line with a wild-type line in nonselective media. After 16-20 h of coculture, cells were plated in the appropriate media to select for fusion products - either HAT (hypoxanthine, aminopterin, thymidine) plus ouabain or AA (alanosine, adenine) plus ouabain - to determine the number of colony-forming cells (fusion products) present per 104 cells plated. When both subpopulations of the pair in the fusion mixture were metastatic, a significantly greater number of fusion products was recovered than if one or both of the subpopulations in the fusion mixture was nonmetastatic, with one exception: line 410 readily fused with both 66cl4 and 44FTO. Subline 410 was highly metastatic when originally isolated but lost its metastatic competence after a brief time in tissue culture.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jcb.240360204
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  • 2
    Digitale Medien
    Digitale Medien
    Addition of magnetic field capability to existing extremely-low-frequency electric field exposure systems (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 10 (1989), S. 85-98 
    Details
    ISSN: 0197-8462
    Schlagwort(e): ELF ; magnetic fields ; exposure systems ; biological effects ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Physik
    Notizen: Magnetic field systems were added to existing electric field exposure apparatuses for exposing cell suspensions in vitro and small animals in vivo. Two horizontally oriented, rectangular coils, stacked one directly above the other, have opposite electric currents. This configuration minimizes leakage fields and allows sham- and field-exposure systems to be placed in the same room or incubator. For the in vitro system, copper plates formed the loop-pair, with up to 900 A supplied by a 180:1 transformer. Electric fields were supplied via electrodes at the ends of cell-culture tubes, eight of which can be accommodated by each exposure system. Two complete systems are situated in an incubator to allow simultaneous sham and field exposure up to 1 mT. For the in vivo system, four pairs of 0.8 × 2.7-m coils made of copper bus bar are employed. This arrangement is energized from the power grid via a 30:1 transformer; horizontal magnetic flux densities up to 1 mT can be generated. Pairs of electrode plates spaced 30.5 cm apart provide electric field exposure of up to 130 kV/m. Four systems with a capacity of 48 rats each are located in one room. For both the in vitro and in vivo systems, magnetic exposure fields are uniform to within ± 2.5%, and sham levels are at least 2,500-fold lower than exposure levels. Potential confounding factors, such as heating and vibration, were examined and found to be minimal.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bem.2250100109
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  • 3
    Digitale Medien
    Digitale Medien
    Monoclonal antibodies against plant proteins recognise animal intermediate filaments (1987)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 8 (1987), S. 312-323 
    Details
    ISSN: 0886-1544
    Schlagwort(e): plant cytoskeleton ; Chlamydomonas ; anti-IFA ; onion root tip cells ; immunoflurescence ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Four monoclonal antibodies were raised against polypetides present in a highsalt detergent-insoluble fraction from cells of Chlamydomonas reinhardtii. Indirect immunofluorescence microscopy of fibroblasts and epithelial cells grown in culture using these plant antibodies revealed staining arrays identical to those obtained with well characterised antibodies to animal intermediate filaments. Immunoflurescence microscopy of Chlamydomonas with these monoclonal antibodies and a monoclonal antibody that recognises all animal intermediate filaments (anti-IFA) gave a diffuse, patchy cytoplasmic staining pattern. Both the plant antibodies and anti-IFA stained interphase onion root tip cells in a diffuse perinuclear pattern. In metaphase through to telophase, the labelling patterns colocalised with those of microtubules. Labelling of the phragmoplast was also detected but not staining of the preprophase band. On Western blots of various animal cell lines and tissues, all the antibodies labelled known intermediate filament proteins. On Western blots of whole Chlamydomonas proteins, all the antiboides labelled a broad band in the 57,000 Mr range, and three antibodies labelled bands around 66,000 and 140,000 Mr but with varibale intensites. On Western blots of whole onion root tip proteins, all the antibodies labelled 50,0000 Mr (two to three bands) polypetides and a diffuse and around 60,000 Mr and three of the antibodies also labelled several polypeptides in the 90,000-200,000 Mr range. The consistent labelling of these different bands by several different monoclonal antibodies recognising animal intermediate filaments makes these polypetides putative plant intermediate filament proteins.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cm.970080404
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  • 4
    Digitale Medien
    Digitale Medien
    Reproductive capacity of sea urchin centrosomes without centrioles (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 13 (1989), S. 264-273 
    Details
    ISSN: 0886-1544
    Schlagwort(e): microtubules ; microtubule organizing center ; mitosis ; monaster ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: For animal cells, the relative roles of the centrioles and the pericentriolar material (the cenrosomal microtubule organizing center) in controlling the precise doubling of the centrosome before mitosis have not been well defined. To this end we devised an experimental system that allowed us to characterize the capacity of the centrosomal microtubule organizing center to double regularly in the absence of centrioles. Sea urchin eggs were fertilized, stripped of their fertilization envelopes, and fragmented before syngamy. Those activated egg fragments containing just the female pronucleus assembled a monaster at first mitosis. A serial section ultrastructural analysis of such monasters revealed that the radially arrayed microtubules were organized by a hollow fenestrated sphere of electrondense material, of the same appearance as pericentriolar material, that was devoid of centrioles. We followed individual fragments with only a female pronucleus through at least three cell cycles and found that the monasters did not double between mitoses. The observation that fragments with only a male pronucleus repeatedly divided in a normal fashion indicates that the assembly and behavior of monasters were not artifacts of egg fragmentation. Our results demonstrate that the activity that controls the precise doubling of the centrosome before mitosis is distinct and experimentally separable from the centrosomal microtubule organizing center. Our observations also extend the correlation between the reproductive capacity of a centrosome and the number of centrioles it contains (G Sluder and CL Rieder, 1985a: J. Cell Biol. 100:887-896). For a cell that normally has centrioles, we show that a centrosome without centrioles does not reproduce between mitoses.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cm.970130405
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  • 5
    Digitale Medien
    Digitale Medien
    Growth, enzyme activity, sugar transport, and hormone supplement responses in cells cloned from a pig kidney cell line LLC-PK1 (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 139 (1989), S. 538-549 
    Details
    ISSN: 0021-9541
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Three clones of the pig kidney cell line LLC-PK1 were isolated and characterized with regard to morphology, growth, proximal tubule enzyme activity, sugar uptake capacity, and hormone and drug responsiveness in a defined medium. Clone N4 was similar in morphology to the wild type (WT), whereas clone F8 showed loose attachment to the substrate, formed large, sweeping domes, and had an elongated desmosome junction between cells. The third clone, F2, did not form domes and showed a marked reduction in growth rate. Cultures of WT, N4, and F8 had higher specific activities of the enzymes alkaline phosphatase and γ-glutamyl transpeptidase at confluence relative to growing cells; however, there was no evidence of an increase in activity of either enzyme at confluence in F2. Phlorizin-sensitive α-methyl-D-glucoside uptake and cytochalasin B-sensitive 2-deoxy-D-glucose uptake were measured in confluent cultures grown on porous filter supports. None of the clones lacked either of the hexose transport systems, although quantitative differences were evident. N4 cells grown in a defined medium in 96-well culture plates were tested in situ for their enzyme responses to differentiation inducers, tumor promoters, and hormones. Alkaline phosphatase activity was significantly increased at confluence by serum, parathyroid hormone (PTH), and vasopressin (AVP), and was decreased by tetradecanoylphorbol acetate (TPA) and epinephrine (EPI). Glutamyl transpeptidase activity was decreased at confluence by serum, TPA, and EPI. Similar tests on α-methyl-D-glucoside uptake showed that serum, TPA, PTH, and AVP had no significant effect on phlorizin-sensitive uptake; however, calcitonin increased uptake by 84% (n = 18). It was concluded that LLC-PK1 clones maintained in a defined medium are useful models for studying renal cell function.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jcp.1041390313
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  • 6
    Digitale Medien
    Digitale Medien
    Respiration supported nitrogenase activity of isolated Rhizobium meliloti bacteroids (1988)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 38 (1988), S. 35-49 
    Details
    ISSN: 0730-2312
    Schlagwort(e): alfalfa ; dicarboxylic acid ; energy source ; chlorpromazine ; bacteroid ; nitrogenase ; respiration ; rhizobium meliloti ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Bacteroids having a high level of respiration-supported nitrogenase activity were isolated from nitrogen-fixing alfalfa root nodules. Gentle maceration under anaerobic conditions in the presence of sodium succinate and a fatty acid scavenging agent were employed in this method.A large proportion of isolated bacteroids retained a triple membrane structure as shown by transmission electron microscopy. Dicarboxylic acids of the TCA cycle (malate, fumarate, succinate), but not glutamate or aspartate, supported sufficient respiratory activity to supply the nitrogenase system with ATP and reducing equivalents and to protect the nitrogenase system from inactivation by 4% oxygen over a period of 20-30 min. Sugars did not support nitrogenase activity in intact bacteroids. The properties of the isolated bacteroids were ascribed to minimal damage to the cytoplasmic membrane and peribacteroidal membrane during isolation.With succinate as substrate and oxygen as terminal electron acceptor, initial nitrogenase activity was determined at 4% oxygen in the gas phase of the assay system employed. At this oxygen concentration, the sustained rate of acetylene reduction by respiring bacteroids was linear up to 30 min. Bacteroid activity declined rapidly with time of exposure to oxygen above 4% in the gas phase. The optimum temperature range for this activity was 10-20°C. Nitrogenase activity was measurable at incubation tempertures below 10°C under 4% oxygen. Functionally intact bacteroids had little nitrogenase activity under anaerobic conditions in the presence of an external source of ATP and reductant. Treatment of the bacteroids with chlorpromazine eliminated respirtation-supported activity and rendered the bacteroid cell membrane permeable to external ATP. Bacteroids treated with chlorpromazine had high acetylene reducing activity with external ATP and dithionite in the absence of oxygen.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jcb.240380105
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  • 7
    Digitale Medien
    Digitale Medien
    Inhibition of mammalian collagenases by thiol-containing peptides (1986)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 32 (1986), S. 71-77 
    Details
    ISSN: 0730-2312
    Schlagwort(e): inhibitors ; collagen breakdown ; cleavage site analogues ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: The following thiol-containing peptide analogues of the carboxyl side of the collagenase-sensitive bond of collagen were synthesized and tested as inhibitors of collagenases partially purified from homogenates of rabbit V-2 tumor and culture medium of pig synovium: HSCH2CH(CH3)CO-Ala-OEt (I), HSCH2CH-(CH2Ph)CO-Ala-OEt (II), HSCH2CH[CH2CH(CH3)2]CO-Ala-OEt (III); HSCH2, CH-[CH2CH(CH3)2]CO-Ala-Gly-OEt (IV); HSCH2CH[CH2CH(CH3)2]CO-Ala-Gly-Gln (V). The compounds are listed in order of their inhibitory potency when assayed with nonfibrillar-acid-soluble calfskin collagen at pH 7.6, 35°C. The best inhibitor (III) gave 50% inhibition between 1 and 4 μM. II was a competitive inhibitor with a Ki value of 75 μM. The enzymes preferred an isobutyl side chain at the 2-carbon position, and, where tested (III, IV), did not discriminate strongly between stereoisomers at the chiral 2-carbon. Increasing the length of the inhibitor did not markedly increase potency.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jcb.240320108
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  • 8
    Digitale Medien
    Digitale Medien
    Thy-1 is a differentiation antigen that characterizes immature murine erythroid and myeloid hematopoietic progenitors (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 123 (1985), S. 25-32 
    Details
    ISSN: 0021-9541
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: To determine the role of Thy-1 antigen in murine hematopoietic differentiation, bone marrow was treated with anti-Thy-1.2 antibody and complement or complement alone. Growth of immature hematopoietic progenitors, erythroid burst-forming units (BFU-E), and granulocyte/macrophage colony-forming units (CFU-GM) was greatly reduced following antibody and complement treatment and was not restored by mitogen-stimulated spleen cell supernatants. In contrast, more mature erythroid and myeloid progenitors, the erythroid colony-forming unit (CFU-E) and the macrophage progenitor stimulated by L-cell-conditioned media (LCM), were spared by anti-Thy-1.2 antibody and complement treatment. Here, to separate the effects of anti-Thy-1.2 antibody treatment on accessory cells from those on progenitors, splenic T cells and thymocytes were added to treated marrow at ratios of up to 200%. Growth of BFU-E and CFU-GM was not restored. To more precisely replace required accessory cells, male complement-treated marrow was cocultured with female anti-Thy-1.2 antibody and complement-treated marrow. Even marrow cells failed to restore female BFU-E and CFU-GM growth. Fluorescent-activated cell sorting (FACS) and immune sheep red cell rosetting with anti-Thy-1.2-labeled marrow were then performed to determine if immature hematopoietic progenitors bear Thy-1.2-positive fraction, demonstrating the presence of Thy-1.2 on early murine hematopoietic progenitors. CFU-E and CFU-M were present in the Thy-1.2-negative fraction following FACS separation. These data demonstrate that Thy-1.2 is a differentiation antigen, present on at least some murine BFU-E and CFU-GM and lost as they mature to CFU-E and CFU-M.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jcp.1041230105
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  • 9
    Digitale Medien
    Digitale Medien
    Restricted growth of rat kidney proximal tubule cells cultured in serum-supplemented and defined media (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 129 (1986), S. 264-272 
    Details
    ISSN: 0021-9541
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Proximal tubules suitable for in vitro culture were prepared from rat kidney cortex by a Ficoll-gradient centrifugation technique which yielded greater than 94% purity. The tubules were seeded into culture dishes, and cell growth was monitored in both Dulbecco's Modified Eagle's Medium containing 10% fetal calf serum and in a defined medium consisting of 50:50 Ham's F12 and Dulbecco's supplemented with insulin, transferrin, and hydrocortisone. Growth in serum-containing medium was continuous; however, the specific activity of the brush border enzyme alkaline phosphatase decreased rapidly with time, and the culture morphology became fibroblastic by 6 days. Neither collagen-coating of the dishes nor addition of the differentiation inducer hexamethylene-bisacetamide had any significant effect on growth or enzyme activity of the cultured cells. Theophylline, another inducer of differentiation, proved cytotoxic. Growth of proximal tubule cells in defined medium proceeded for 4 days before irreversible growth arrest occurred. Alkaline phosphatase activity and epithelial morphology remained relatively constant throughout the culture period. Additions of the growth factors triiodothyronine, prostaglandin E2, and epidermal growth factor were unable to unblock the growth arrest. If cells cultured in defined medium for 3 days were switched to serum-supplemented medium, continuous growth occurred, but both alkaline phosphatase activity and epithelial morphology were rapidly lost. As a test of the culture method, rabbit proximal tubule cells were cultured under similar conditions in defined medium. Growth was prolific and continuous for up to, but not exceeding, 30 days, and differentiated properties were retained. It was concluded that both rat and rabbit proximal tubule cells have a limited proliferative capacity in vitro but that the capacity of the rat cell to divide is much reduced relative to the rabbit cell.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jcp.1041290219
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  • 10
    Digitale Medien
    Digitale Medien
    Diminished calcium influx in lectin-stimulated T cells from old mice (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 132 (1987), S. 337-342 
    Details
    ISSN: 0021-9541
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: T lymphocytes from aged donors function poorly, but the biochemical basis for the defect remains uncertain. We tested the hypothesis that T cells from old mice had a diminished ability to transmit extracellular signals into the cytoplasm, by measuring intracellular free calcium concentrations (Cai) in T cells stimulated by the polyclonal activator concanavalin A (Con A). Using the second-generation fluorochrome indo-1 as a reporter of Cai, we found that the Con A-induced elevation of Cai levels is reduced both in rate and extent in old T cells, as compared to T cells from young mice. Flow cytometric analysis showed that this age-sensitive change represents a decline, with age, in the number of T cells that can respond to Con A by increasing their Cai above resting baseline levels (100-120 nM). These results thus show that defects in activation are manifested by T cells from old donors within the first 5 minutes of the activation process, and suggest that aging may lead to alterations either in the surface molecules that receive extracellular signals, or in the sequence of coupled events by which these extracellular signals bring about alterations in the intracellular ionic milieu.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jcp.1041320220
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