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  • Electronic Resource  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Abscisic acid activates ATPase in developing apple fruit especially in fruit phloem cells (2003)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 26 (2003), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abscisic acid (ABA) improves the sink strength by promoting the phloem unloading and regulating the assimilate metabolism in the economic sink organs of crops, although its mechanism remains unknown. The present experiment, using the techniques of the in vivo injection of ABA into the intact apple fruit attached to a growing apple tree and the in vivo incubation of the fruit tissue in the ABA-contained medium, showed that ABA strongly activated the fruit ATPase especially P-ATPase, of which the activity was doubled by ABA treatment. This ATPase activation was shown to be in vivo tissue-dependent. The ABA-induced P-ATPase activation was fruit developmental stage-, ABA dose-, medium pH- and incubation time-dependent. Physiological active (+)ABA was shown more effective to stimulate P-ATPase activity than (+/–)ABA, and two ABA analogues (–)ABA and trans-ABA, had no effect on P-ATPase activation, indicating that only physiologically active cis(+)ABA can induce the enzyme activation, and so the ABA-induced effects are stereospecific. The protein synthesis inhibitor cycloheximide was shown to have no effect on P-ATPase activation by ABA, suggesting that synthesis of new proteins was not involved in the enzyme activation. The cytochemical assay revealed that P-ATPase was activated by ABA in both the phloem and its surrounding flesh parenchyma cells, and that the most strongly P-ATPase activation was observed in the plasma membrane of sieve element/companion cell complex. These data suggest that the improvement of phloem unloading by ABA previously reported in this fruit as in other crop sink organs may be attributed, at least partly, to the ABA-induced ATPase activation especially in phloem cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.2003.01057.x
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  • 2
    Electronic Resource
    Electronic Resource
    Polycaprolactone/glass bioabsorbable implant in a rabbit humerus fracture model (1997)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 36 (1997), S. 536-541 
    Details
    ISSN: 0021-9304
    Keywords: polycaprolactone ; bioabsorbable ; internal fixation ; fracture fixation ; polymer ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Research in improved materials and methods for internal fixation has centered on internal fixators made of bioabsorbable materials such as polylactic acid, polyglycolic acid, and polyparadioxanone. These materials have two problems: the first is a postoperative complication related to a delayed inflammatory response; and the second is low strength characteristics. An alternative material developed to alleviate these problems is a composite of phosphate glass fibers embedded in the polymer polycaprolactone, referred to as PCL. In this study, intramedullary pins made of PCL were compared to stainless steel pins in a rabbit humerus osteotomy model. Specimens were harvested at 0, 6, and 12 weeks postoperatively, radiographs and mechanical testing to failure were performed at each time interval, and tissue was examined microscopically at 6 and 12 weeks. Histologic results showed PCL pins to be well tolerated with minimal inflammation around the pin. Mechanical testing revealed the PCL fixation to be weaker initially than the stainless steel fixation. There was significant stress shielding of stainless-steel-healed rabbit humeri when compared to the PCL/bone humeri. All osteotomies immobilized with PCL healed with abundant periosteal callus production. © 1997 John Wiley & Sons, Inc. J Biomed Mater Res, 36, 536-541, 1997.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
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