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  • 1985-1989  (248)
  • 1988  (248)
  • Cell & Developmental Biology  (219)
  • Column liquid chromatography  (29)
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 135 (1988), S. 488-494 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The role of cAMP and calcium in the induction of ornithine decarboxylase (ODC, E.C.4.1.1.17) activity in the osteogenic sarcoma cell line, UMR 106-01, was studied, with particular interest for parathyroid hormone (PTH). PTH and forskolin dose-dependently induced the ODC activity and the cAMP production. Protein synthesis is involved in the effect of PTH and forskolin on ODC activity but not on cAMP production. Using quin2 we showed that 20 nM PTH and 10 μM forskolin increased the intracellular ionized calcium concentration ([Ca2+]i), thereby offering the possibility for calcium to play a role as cellular mediator in the action of PTH and forskolin in bone. Data obtained with A23187 showed that solely an increase of the [Ca2+]i is not sufficient to stimulate basal or potentiate PTH- and forskolin-induced ODC activity. However, the effects of calcium channel blockers and EGTA on basal and PTH- and forskolin-induced ODC activity point to a specific role for calcium. Moreover, the effects of calcium channel blockers and EGTA on basal and PTH- and forskolin-induced cAMP production indicate that the involvement of calcium in the induction of ODC activity is primarily located at another site than the adenylate cyclase. These data indicate that calcium is involved in the control of basal ODC activity. Furthermore, these data suggest that both cAMP and calcium are involved in the induction of ODC activity by PTH and forskolin. More precisely, ODC activity in UMR 106-01 cells can be induced by PTH and forskolin via a calcium-dependent cAMP messenger system.
    Additional Material: 3 Ill.
    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: The binding of iodinated basic fibroblast growth factor (bFGF) to low-density heparan sulfate proteoglycan purified from the Engelbreth Holm Swarm (EHS) sarcoma was investigated using different techniques. The tumor clearly contained bFGF, the level being comparable to that found in other tissues such as human or bovine brain. 125I bFGF strongly bound to the basement membrane-like matrix of EHS frozen sections as revealed by autoradiography. Iodinated bFGF bound to purified heparan sulfate proteoglycan but not to laminin or collagen type IV, three components isolated from the same tumor. In contrast, acidic fibroblast growth factor (aFGF) displayed negligible binding to heparan sulfate proteoglycan. Binding of bFGF to frozen sections and to purified proteoglycan could be strongly inhibited by heparin and was displaced by an excess of unlabeled factor and completely suppressed after heparitinase and heparinase treatments. Binding was a function of the salt concentration and was abolished at 0.6 M NaCl. Scatchard analysis indicated the affinity site had a Kd of about 30 nM, a value 10-15 higher than that recently reported by Moscatelli (J. Cell. Physiol., 131:123-130, 1987) in the case of the low-affinity binding sites present on the surface of baby hamster kidney (BHK) cells.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 25 (1988), S. 870-874 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Gel-permeation ; Pectinase activity ; Aspergillus Niger andRhizopus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A rapid liquid chromatographic (HPLC) method for the determination of pectinolytic activity of enzymes produced by Aspergillus Niger and Rhizopus species is reported. Compared with more conventional methods, HPLC is more reliable and has a much improved maximum sensitivity. The limit of quantitation of galacturonic acid is 0.1μg.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0730-2312
    Keywords: cyclin ; proliferating cell nuclear antigen ; cloned T lymphocytes ; interleukin 2 ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Expression of cyclin, a non-histone nuclear protein, during recombinant interleukin 2 (rIL2)-driven cell-cycle progression of cloned T lymphocytes has been assessed. We found that expression of cyclin protein, as detected by immunofluorescence, is tightly associated with proliferation, and not merely S-phase, of L2 cells stimulated with rIL2. Cyclin immunofluorescence was detected in all cell-cycle phases (G1/S/G2/M, as detected by flow cytometry) of proliferating L2 cells. Accumulation of cyclin mRNA levels was induced as early as 1 h after stimulation, was maximal at 25-49 h, and remained elevated throughout stimulation, as detected by Northern blot analysis. A cDNA-encoding murine cyclin was cloned from a cDNA library prepared from IL2-stimulated cloned T cells. The sequence of the 5′ end of the murine cyclin cDNA was determined and found to be 88% and 82% similar to the sequences of cDNA clones encoding rat and human cyclin, respectively. The present studies demonstrate that cyclin protein and mRNA accumulation are highly regulated during IL2-induced proliferation of a cloned T cell. These data provide a framework for addressing the molecular mechanisms regulating cyclin gene expression during cellular proliferation.
    Additional Material: 4 Ill.
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  • 5
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The aim of this paper is to summarize some of our quantitative descriptive and experimental studies, to discuss them in view of the literature data, and to present a synthesis of the topic.The results of stereological analysis of some tissue components of the rat thyroid gland have been compared with the results of topological studies on the parafollicular cells of various mammalian species. Localization of the parafollicular cells in the central regions of the thyroid gland lobes, where the follicular cell activity seems to be greater than in the periphery of the lobes, has led to the hypothesis that the parafollicular cells regulate (stimulate and/or suppress) the activity of the follicular cells.Long-term application and antithyroid drugs to mice and rats has shown that excessive concentrations of thyrotropin provoke hyperplashia of both the follicular cells and the intrathyroid mast cells and, transiently, of the parafollicular cells. This and some of the literature data are congruent with the hypothesis that the parafollicular and mast cells also stimulate the follicular cells by their paracrine secretions.Long-term application of antithyroid drugs to mice and rats has shown that excessive concentrations of cular cells but also probably stimulation of the follicular cells, as judged by the stereological measurements.The biological meaning of the spatial integration of follicular and parafollicular cells seems to be a functional coordination of both epithelial cell lines, supported by intrathyroid mast cells.
    Additional Material: 12 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 136 (1988), S. 81-87 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Chondrogenesis was monitored in micromass cultures of mesenchymal cells derived from the distal tip of stage-25 chick limb buds over a 6-day period. Alcian green staining and immunofluorescent localization of cartilage-specific proteoglycans revealed the appearance of cartilage matrix by day 3 of cell culture. By day 6, cultures contained a uniform and homogeneous population of fully differentiated chondrocytes throughout the cell layer, with only a narrow rim of nonchondrogenic cells around the extreme periphery of the culture. Synthesis of sulfated glycosaminoglycans also progressively increased between days 3 and 6, being 8-fold higher at day 6 than at day 1 of culture. Both adenylate cyclase (AC) activity and cAMP concentrations increased dramatically during the first 2 days of culture, reaching maximal levels by day 2, which remained elevated and stable throughout the remaining chondrogenic period (days 3-6). Responsiveness of both AC and cAMP concentrations of the cells to PGE2 was maximal by day 1 of culture and was increased over control cells by 12-fold and 8-fold respectively. Both responses, however, were dramatically reduced by day 3, at which time the initiation of cartilage formation was apparent. Responsiveness of cells during the prechondrogenic period to PGE2 was relatively specific in that no effects could be demonstrated with equivalent concentrations of PGF2α or 6-keto-PGF1α, although PGl2 did produce increases in cAMP concentrations of about 50% of those of PGE2. These results indicate that previously reported changes in the cAMP system in heterogeneous cell cultures derived from whole limb buds reflect changes occurring in the chondrogenic cell type and indicate further that peak responsiveness of the cAMP system of these cells to prostaglandins is restricted to prechondrogenic developmental periods.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0886-1544
    Keywords: video microscopy ; axonal transport ; computer motion analysis ; giant axon ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Moving intra-axonal organelles demonstrate frequent variations in speed when viewed over several seconds. To evaluate these and other motion variations, a long-term analysis of organelle motion in isolated axoplasm of Myxicola infundibulum was carried out using differential interference contrast optics and analog and digital image enhancement techniques. Motion characteristics of individual organelles were analyzed for periods of up to 58 minutes. Three principle observations on organelle motion were made: (1) Classes of organelles of the same size demonstrated a 5- to 25-fold variation of speed, with the slowest speeds occurring most frequently; (2) organelle speeds over individual translocations (motion without stopping) are inversely proportional to their size, but the speeds calculated for the long-term analysis of organelle motion (total distance travelled/total observation time, including pauses) did not reflect this observation; and (3) organelles displayed variable trip lengths, durations, mean speeds, and pause durations, and the relationships between these variations showed no repetitive patterns. In contrast to reported observations of uniform velocities of organelles moving on isolated microtubule preparations, these observations suggest that a variety of factors must play a role in organelle translocation in Myxicola axoplasm.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 11 (1988), S. 16-23 
    ISSN: 0886-1544
    Keywords: crawling motility ; substrate adhesion ; monoclonal antibodies ; membrane flow ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Caenorhabditis elegans sperm are nonflagellated cells that lack actin and myosin yet can form pseudopods to propel themselves over solid substrates. Surface-attached probes such as latex beads, lectins, and antimembrane protein monoclonal antibodies move rearward over the dorsal pseudopod surface of sessile cells. Using monoclonal antibodies against membrane proteins of C. elegans sperm to examine the role of localized membrane assembly and rearward flow in crawling movement, we determined that substrates prepared by coating glass with antimembrane protein antibodies, but not naked glass or other nonmembrane-binding proteins, promote sperm motility. Sperm locomotion is inhibited in a concentration-dependent fashion when cells are bathed with soluble antimembrane protein monoclonal antibodies but not with antimouse Ig antibodies or a monoclonal antibody against a sperm cytoplasmic protein. Our results suggest that C. elegans sperm crawl by gaining traction with substrate-attached ligands via their surface proteins and by using the motor that moves those proteins rearward on unattached cells to pull the entire cell forward. Continuous insertion of new proteins at the front of the cell and their subsequent adhesion to the substrate allows this process to continue.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 26 (1988), S. 369-371 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Urinary trypsin inhibitors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Human urine contains a family of trypsin inhibitors. Procedures for their purification and characterization involve laborious techniques and the conclusions are different in the identification of the separated compounds. We report results obtained by applying our RP-HPLC method to some procedures adopted by different authors.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Silica modifiers ; Aromatic hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention parameters of benzene, naphthalene; anthracene and phenanthrene on untreated silica gel were determined in the presence of four modifiers: 1-methyl-2-pyrrolidone (MP), 4-formyl morpholine (FM), γ-butyrolactone (BL) and sulfolane (SF). Better column performance was found in the case of FM and MP only.
    Type of Medium: Electronic Resource
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