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  • 1
    Electronic Resource
    Electronic Resource
    Effect of Transient Focal Ischemia of Mouse Brain on Energy State and NAD Levels (2000)
    Oxford UK : Blackwell Science Ltd.
    Journal of neurochemistry 75 (2000), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: It has been proposed that NAD depletion resulting from excessive activation of poly(ADP-ribose) polymerase is responsible for secondary energy failure after transient cerebral ischemia. However, this hypothesis has never been verified by measurement of ATP and NAD levels in the same tissue sample. In this study, we therefore investigated the effect of transient focal cerebral ischemia on the temporal profiles of changes in the levels of energy metabolites and NAD. Ischemia was induced in mice by occluding the left middle cerebral artery using the intraluminal filament technique. Animals were subjected to 1-h ischemia, followed by 0, 1, 3, 6, or 24 h of reperfusion. During ischemia, ATP levels, total adenylate pool, and adenylate energy charge dropped to ∼20, 50, and 40% of control, respectively, whereas NAD levels remained close to control. Energy state recovered transiently, peaking at 3 h of recovery (ATP levels and total adenylate pool recovered to 78 and 81% of control). In animals subjected to reperfusion of varying duration, the extent of ATP depletion was clearly more pronounced than that of NAD. The results imply that depletion of NAD pools did not play a major role in secondary disturbances of energy-producing metabolism after transient focal cerebral ischemia. Changes in ATP levels were closely related to changes in total adenylate pool (p 〈 0.001). The high energy charge after 6 h of reperfusion (0.90 versus a control value of 0.93) and the close relationship between the decline of ATP and total adenylate pool suggest that degradation or a washout of adenylates (owing to leaky membranes) rather than a mismatch between energy production and consumption is the main causative factor contributing to the secondary energy failure observed after prolonged recovery.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2000.0751675.x
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  • 2
    Electronic Resource
    Electronic Resource
    Changes in the phosphorylation of initiation factor eIF-2α, elongation factor eEF-2 and p70 S6 kinase after transient focal cerebral ischaemia in mice (2001)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 78 (2001), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Mice were subjected to 60 min occlusion of the left middle cerebral artery (MCA) followed by 1–6 h of reperfusion. Tissue samples were taken from the MCA territory of both hemispheres to analyse ischaemia-induced changes in the phosphorylation of the initiation factor eIF-2α, the elongation factor eEF-2 and p70 S6 kinase by western blot analysis. Tissue sections from additional animals were taken to evaluate ischaemia-induced changes in global protein synthesis by autoradiography and changes in eIF-2α phosphorylation by immunohistochemistry. Transient MCA occlusion induced a persistent suppression of protein synthesis. Phosphorylation of eIF-2α was slightly increased during ischaemia, it was markedly up-regulated after 1 h of reperfusion and it normalized after 6 h of recirculation despite ongoing suppression of protein synthesis. Similar changes in eIF-2α phosphorylation were induced in primary neuronal cell cultures by blocking of endoplasmic reticulum (ER) calcium pump, suggesting that disturbances of ER calcium homeostasis may play a role in ischaemia-induced changes in eIF-2α phosphorylation. Dephosphorylation of eIF-2α was not paralleled by a rise in levels of p67, a glycoprotein that protects eIF-2α from phosphorylation, even in the presence of active eIF-2α kinase. Phosporylation of eEF-2 rose moderately during ischaemia, but returned to control levels after 1 h of reperfusion and declined markedly below control levels after 3 and 6 h of recirculation. In contrast to the only short-lasting phosphorylation of eIF-2a and eEF-2, transient focal ischaemia induced a long-lasting dephosphorylation of p70 S6 kinase. The results suggest that blocking of elongation does not play a major role in suppression of protein synthesis induced by transient focal cerebral ischaemia. Investigating the factors involved in ischaemia-induced suppression of the initiation step of protein synthesis and identifying the underlying mechanisms may help to further elucidate those disturbances directly related to the pathological process triggered by transient cerebral ischaemia and leading to neuronal cell injury.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2001.00462.x
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  • 3
    Electronic Resource
    Electronic Resource
    Investigation of Time-Dependent Behavior of Starch-Based, Injection Molded Biodegradable Polymer (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 589 (June 2008), p. 281-286 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Nowadays as a result of the increasing environmental friendly consciousness and thedecreasing oil reserves, natural origin based materials are developed. These materials are not onlybased on renewable, natural resources, but capable of biodegradation in compost. Thesebiodegradable polymers (biopolymers) can be inserted into the nature’s recycling process. One ofthe most important biopolymers is starch. Starch can be processed like a thermoplastic material byadding plasticizers, creating the so called thermoplastic starch. However the price of starch is ratherlow, it has certain drawbacks retarding its wide industrial usage. It is sensitive to moisture, disruptsin pure water, has low mechanical properties, and in time it ages. This ageing or time-dependentbehavior was analyzed with injection molded tensile specimens. The shrinkage and mechanicalproperties of the specimens were determined as a function of ageing time. The fracture surface wasanalyzed by scanning electron microscope. The results of the measurements were compared withprevious examinations
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/19/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.589.281.pdf
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