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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Protoplasma 109 (1981), S. 209-216 
    ISSN: 1615-6102
    Keywords: Amoeboid movement ; Particle motion ; Saltation ; Streaming ; Videomicroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Various types of cell motility have been observed and analyzed with techniques of increasing sensitivity and sophistication. Photokymography, cinemicrography and laser-Doppler spectroscopy have all made important contributions to our knowledge of cytoplasmic streaming and cell movement. Now videomicroscopy is finding applications in recording and analyzing two different kinds of images. Video intensification microscopy by image intensifiers and silicon intensified target (SIT) video cameras is used to intensify images too dim to be viewed by eye or photographed. On the other hand, video enhanced microscopy uses a less sensitive chalnicon or other vidicon camera with adjustable amplification and offset to enhance the contrast and improve the resolution of microscopes that employ instrumental compensators. Both of these videotechniques have greatly extended the usefulness of the optical microscope: image intensification to brighten dim images and video enhancement to improve the contrast and resolution so that even “submicroscopic” structures and events can be recorded. These video techniques can both be further extended by a frame memory, with which images can be further enhanced by computer processing. Still to be developed, however, are appropriate methods for automatic tracking of particle motions.
    Type of Medium: Electronic Resource
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  • 12
    ISSN: 1615-6102
    Keywords: Acidosomes ; Concanamycin B ; Phagosomes ; Proton pumps ; Paramecium ; Vacuolar ATPase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Although it is generally accepted that phagosome acidification is induced through the activity of a vacuolar proton pump (V-ATPase) present on the phagosome membrane, exactly how these pumps are delivered to the phagosomes is not well understood. To study this question inParamecium, it was necessary to first show that an authentic V-ATPase was present on their phagosomal membranes. Three antibodies raised against V-ATPases or their subunits were each found to label one or two large digestive vacuoles (DVs) inParamecium multimicronucleatum when immunofluorescence microscopy was used. Using horseradish peroxidase immunocytochemistry to increase sensitivity, about 10 DVs were shown to contain a V-ATPase. In high magnification images and cryoultramicrotomy these proton pumps were found to be located on the acidosomes, suggesting the vacuolar proton pumps on the DVs originate from the acidosomes. The authenticity of the V-ATPase was further confirmed by its sensitivity to cold temperature and to the V-ATPase specific inhibitor, concanamycin B, which at 10 nM doubled the t1/2 for vacuole acidification. Thus, we conclude that (1) acidosomes and some DVs ofParamecium have a bona-fide concanamycin B-sensitive and cold-sensitive V-ATPase, (2) the V-ATPase is delivered to the young DVs during acidosome fusion, and (3) the V-ATPase is involved in vacuole acidification. Finally, we have now determined thatParamecium has two immunologically related V-ATPases that are involved in two very different functions, (1) the acidification of phagosomes and (2) fluid segregation in the contractile vacuole complexes.
    Type of Medium: Electronic Resource
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  • 13
    ISSN: 1617-4623
    Keywords: Sunflower ; Albumin gene ; DNA sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The complete sequence of a sunflower (Helianthus annuus) gene, HaG5, encoding a 2 S albumin storage protein was determined. The predicted unprocessed precursor has 295 amino acids, is rich in glutamine residues (24%) and contains a hydrophobic amino-terminus that is similar to the consensus signal peptide. Amino acid sequencing of the mature protein revealed extensive post-translational processing. Nuclease protection and primer extension analysis indicated a major transcriptional start 30 nucleotides 5′ of the predicted ATG start codon. Additional sequence data, determined from a nearly full length cDNA recombinant, indicate that HaG5 is a member of a small gene family comprised of at least two divergent genes. Comparison of the predicted HaG5 gene product with sequences of other known plant proteins revealed distant but significant homology with the napins of Brassica and other heterogeneous seed proteins in the albumin superfamily.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Polymer bulletin 15 (1986), S. 127-134 
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary A method has been developed which provides very pure alkyl methacrylate monomers for anionic polymerization. This method takes advantage of the chemistry of trialkylaluminum compounds-their reactivity with alcohols and moisture, and their complex formation with methacrylic esters which facilitates titration of impurities. When coupled with previously known polymerization techniques, this purification methodology allows for both the synthesis of narrow distribution poly(alkyl methacrylates) of controlled and predictable molecular weight and for the utilization of a wide variety of methacrylate monomers. The procedure described herein should be equally applicable to group transfer polymerization.
    Type of Medium: Electronic Resource
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  • 15
    ISSN: 0886-1544
    Keywords: birefringence ; Physarum ; acellular slime mold ; cytoplasmic streaming ; contractility ; rhythm ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Birefringent fibrils (BRFs) with a positive sign composed of bundles of F-actin were found throughout the Physarum plasmodium with the mode of existence differing regionally. In the zone behind the leading edge of an advancing plasmodium, where cytoplasmic sol and gel were still not well differentiated, more BRFs came to the foreground when the endoplasm flowed backward (emptying phase), and a substantial portion disappeared when the endoplasm flowed forward (filling phase), except for nodes, from which BRFs were reorganized in the early emptying phase of each cycle. BRFs found in the wall of the streaming channel in the posterior network and the branched vein section ran in parallel to or helically around the channel. They were much more stable and maintained strong birefringence irrespective of the direction of the cytoplasmic flow. When the fan-like expanse ceased moving forward, the BRFs no longer appeared and disappeared cyclically but persisted in the area which had previously been the front. We concluded that the site of the active contraction-relaxation rhythm in an advancing plasmodium with antero-posterior polarity is restricted to its frontal zone and that the rest of the plasmodium is in a state of “tonus” which continuously imparts a certain level of hydrostatic pressure to the interior. The meaning of the tonus and the mechanics of tensile force production in the plasmodium are discussed in terms of a working hypothesis arrived at from the phase relationship between isometric and isotonic contraction waves.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. 113-121 
    ISSN: 0886-1544
    Keywords: coelomocytes ; filopodia ; whole cell translocation ; video microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have utilized a video-enhanced contrast system coupled to a DIC-equipped microscope to examine the motility of both whole coelomocytes and individual filopodia. When the cells are left in diluted coelomic fluid, they exhibit a fibroblast-like mode of translocation across the substrate. These cells extend lamellipodia at their advancing margin and develop retraction fibers at the trailing edge. Filopodia are actively extended from the lamellipodia of the advancing margin. Cells that are washed free of the coelomic fluid and placed in an isotonic buffer lose their ability to translocate. Filopodia on these stationary cells are seen to undergo a series of waving and bending motions. These motions are rapid and result in a filopodium folding back upon itself only to reextend later. Both forms of motility are discussed in light of the existing structural and biochemical knowledge of this and other cell types.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 17
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 29 (1989), S. 960-964 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A new approach to resist materials that exhibit chemical amplification is based on systems comprised of three structural units at least one of which is polymeric: (a) an aromatic moiety such as poly(4-hydroxystyrene), Novolac, or other aromatic compounds which are susceptible to electrophilic aromatic substitution; (b) a latent electrophile which may be polyfunctional and, in the case of this study, is a carbocation precursor; (c) a material which generates strong acid upon irradiation. Exposure of a film containing these three structural components affords a latent image of acid dispersed in the polymer matrix. In a subsequent baking step, the photogenerated acid reacts with the latent electrophile releasing a very reactive carbocationic species which becomes bound to the aromatic moiety. As one of the components of the resist is polymeric and multifunctional, the result is a rapid increase in molecular weight due to branching and crosslinking of the chains. In terms of imaging, this process translates into the formation of a negative image of the mask although under some conditions a positive image may also be produced. The system shows a very high sensitivity and can provide high resolution images devoid of distortion due to the absence of swelling during development.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 46 (1992), S. 757-762 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A new technique using oxygen plasma etching was developed for studying the dispersion of filler particles in polymer solids. With this method, the organic polymer matrix is selectively etched from the top surface down into the bulk, revealing the dispersion state of the filler particles upon scanning electron microscopic analysis. A polymer composite, comprised of zinc oxide particles and a linear styrene-n-butylmethacrylate copolymer, was used to investigate the particle dispersion as a function of filler volume fraction. Preliminary data on the effect of a surfactant on filler dispersion is also discussed. © 1992 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 19
    Publication Date: 2014-06-13
    Description: Novel broad-spectrum antimicrobials are a critical component of a strategy for combating antibiotic-resistant pathogens. In this study, we explored the activity of the broad-spectrum antiviral compound ST-669 for activity against different intracellular bacteria and began a characterization of its mechanism of antimicrobial action. ST-669 inhibits the growth of three different species of chlamydia and the intracellular bacterium Coxiella burnetii in Vero and HeLa cells but not in McCoy (murine) cells. The antichlamydial and anti- C. burnetii activity spectrum was consistent with those observed for tested viruses, suggesting a common mechanism of action. Cycloheximide treatment in the presence of ST-669 abrogated the inhibitory effect, demonstrating that eukaryotic protein synthesis is required for tested activity. Immunofluorescence microscopy demonstrated that different chlamydiae grow atypically in the presence of ST-669, in a manner that suggests the compound affects inclusion formation and organization. Microscopic analysis of cells treated with a fluorescent derivative of ST-669 demonstrated that the compound localized to host cell lipid droplets but not to other organelles or the host cytosol. These results demonstrate that ST-669 affects intracellular growth in a host-cell-dependent manner and interrupts proper development of chlamydial inclusions, possibly through a lipid droplet-dependent process.
    Print ISSN: 0066-4804
    Electronic ISSN: 1098-6596
    Topics: Biology , Medicine
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  • 20
    Publication Date: 2016-01-21
    Description: Objectives To describe the beliefs and attitudes to organ donation in the Arabic-speaking community. Design Arabic-speaking participants were purposively recruited to participate in 6 focus groups. Transcripts were analysed thematically. Participants 53 participants, aged 19–77 years, and originating from 8 countries, participated in 1 of 6 focus groups. Participants identified as Christian (73%), Islam (26%), Buddhist (2%) or did not identify with any religion (2%). Results 6 themes (with subthemes) were identified; religious conviction; invisibility of organ donation; medical suspicion; owning the decision; and reciprocal benefit. Conclusions Although organ donation is considered a generous life-saving ‘gift’, representative members of the Arabic-speaking community in Australia were unfamiliar with, unnerved by and sceptical about the donation process. Making positive decisions about organ donation would likely require resolving tensions between respecting family, community and religious values versus their individual autonomy. Providing targeted education about the process and benefits of organ donation within the Arabic community may clarify ambiguities surrounding cultural and religious-based views on organ donation, reduce taboos and suspicion towards donation, and in turn, lead to increased organ donation rates.
    Keywords: Open access, Intensive care, Qualitative research, Renal medicine
    Electronic ISSN: 2044-6055
    Topics: Medicine
    Published by BMJ Publishing
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