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  • Articles  (2)
  • 20 nm colloidal gold  (1)
  • 550 - Earth sciences
  • Humans
  • Life and Medical Sciences
  • 1995-1999  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Pharmaceutical research 16 (1999), S. 1743-1747 
    ISSN: 1573-904X
    Keywords: sedimentation FFF ; 20 nm colloidal gold ; size ; size distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. Assessment of lower size limit of Sedimentation Field-Flow Fractionation (SedFFF), specifically to evaluate if the method is suitable to determine the size and size distribution of 20 nm colloidal gold particles with high resolution. Methods. Sedimentation Field-Flow Fractionation was used to determine the size of the colloidal particles. Due to the high density of gold it was possible to extend the lower size limit of SedFFF well below 20 nm. The size distribution of a gold colloid was obtained from the peak broadening caused by the polydispersity of the sample. The peak broadening due to instrumental imperfections was determined. For comparison purpose the particles were also sized using SEM and PCS. Results. The mean diameter of the particles was determined to be (20.87 ± 0.05) nm, the standard deviation in size being 1.04 nm (about 5%). SEM could confirm that the particles are about 20 nm in diameter. A sizing with PCS was not possible. The particles have a strong tendency to aggregate and PCS yields a diameter that is much too large. Conclusions. At optimized analytical parameters Sedimentation Field-Flow Fractionation is an effective method to measure the size of gold particles as small as 15 nm with an accuracy of about 0.1 nm. The polydispersity of the sample can easily be determined.
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 128-139 
    ISSN: 0192-253X
    Keywords: Spermatogenesis ; meiosis ; synapsis ; synaptonemal complex ; G2-M transition ; okadaic acid ; actinomycin D ; camptothecin ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: An impediment to the investigation of mammalian spermatogenic meiosis has been the lack of an appropriate system for experimental manipulation of meiotic prophase cells. We report here the use of a simple system for the short-term culture of pachytene spermatocytes. We have assayed parameters of cell function pertinent to meiotic prophase, namely chromosome pairing and synapsis. During the culture period of 24-48 hr, cells maintained typical pachytene morphology, chromatin condensation patterns, and chromosome pairing, as assessed by light and electron microscopy. Uridine incorporation, monitored by autoradiography, reflected the chromosomal distribution found in vivo in that the autosomal chromosomes were transcriptionally active, while the sex chromosomes were not. Thus features of chromosome pairing and sex chromatin inactivation are maintained in these cultures. We have conducted experiments to demonstrate that cultured pachytene spermatocytes can be useful for the analysis of agents, some of which may be suspected mutagens, that might affect chromosome structure and function during meiosis. Treatment of cells with actinomycin D revealed a differential effect on chromatin condensation in the autosomes versus the sex chromosomes. Carnptothecin, a topoisomerase inhibitor, induced desynapsis of paired chromosomes. Okadaic acid, a phosphatase inhibitor, induced premature metaphase-I condensation of pachytene chromosomes. This last experiment suggests that these cultured cells may be useful for analysis of meiotic cell cycle controls. Taken together, these results demonstrate a culture system that can be useful for analysis of meiotic events as well as in screening for potential mutagenic agents that might affect meiotic chromosome structure and function. © 1995 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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