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  • 1
    Electronic Resource
    Electronic Resource
    DNase I disinhibition is predominantly associated with actin hyperpolymerization after traumatic brain injury (2001)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 77 (2001), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: To elucidate a role for the cytoskeletal protein actin in post-traumatic apoptotic cell death, the ability of actin-containing tissue extracts to inhibit exogenous DNase I was evaluated. In addition, cortical, hippocampal and thalamic extracts were examined for caspase-mediated actin cleavage and changes in actin polymerization state. Rats were anesthetized, subjected to lateral fluid percussion brain injury of moderate severity, and euthanized at 1 h, 6 h, 24 h, 1 week or 3 weeks post-injury (n = 3 per time-point). Tissue extracts from all brain regions of sham (uninjured) animals inhibited exogenous DNase I activity to a significant extent. However, inhibition of DNase I was significantly reduced at 1 h and 6 h in the injured hippocampus, and at 1 h, 6 h and 3 weeks in the thalamus. DNase I in cortical extracts of all injured animals was inhibited to a similar extent as that in uninjured animals. Actin fragments consistent with caspase-mediated proteolysis were observed in immunoblots of the injured hippocampus and thalamus at 1 h and 24 h, respectively, and were present up to 3 weeks post-injury. Transient actin hyperpolymerization was observed at 1 and 6 h post-injury in the thalamus and hippocampus, while actin depolymerization was observed at 1 and 3 weeks in the cortex and thalamus. Collectively our data suggest that DNase I disinhibition following brain trauma is associated predominantly with actin hyperpolymerization but also with actin depolymerization and concomitant caspase-mediated actin proteolysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2001.00215.x
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  • 2
    Electronic Resource
    Electronic Resource
    Temporal Patterns of Poly(ADP-Ribose) Polymerase Activation in the Cortex Following Experimental Brain Injury in the Rat (1999)
    Oxford UK : Blackwell Science Ltd
    Journal of neurochemistry 73 (1999), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The activation of poly(ADP-ribose) polymerase, a DNA base excision repair enzyme, is indicative of DNA damage. This enzyme also undergoes site-specific proteolysis during apoptosis. Because both DNA fragmentation and apoptosis are known to occur following experimental brain injury, we investigated the effect of lateral fluid percussion brain injury on poly(ADP-ribose) polymerase activity and cleavage. Male Sprague-Dawley rats (n = 52) were anesthetized, subjected to fluid percussion brain injury of moderate severity (2.5-2.8 atm), and killed at 30 min, 2 h, 6 h, 24 h, 3 days, or 7 days postinjury. Genomic DNA from injured cortex at 24 h, but not at 30 min, was both fragmented and able to stimulate exogenous poly(ADP-ribose) polymerase. Endogenous poly(ADP-ribose) polymerase activity, however, was enhanced in the injured cortex at 30 min but subsequently returned to baseline levels. Slight fragmentation of poly(ADP-ribose) polymerase was detected in the injured cortex in the first 3 days following injury, but significant cleavage was detected at 7 days postinjury. Taken together, these data suggest that poly(ADP-ribose) polymerase-mediated DNA repair is initiated in the acute posttraumatic period but that subsequent poly(ADP-ribose) polymerase activation does not occur, possibly owing to delayed apoptosis-associated proteolysis, which may impair the repair of damaged DNA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1999.0730205.x
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  • 3
    Electronic Resource
    Electronic Resource
    Regional and Temporal Alterations in DNA Fragmentation Factor (DFF)-Like Proteins Following Experimental Brain Trauma in the Rat (1999)
    Oxford UK : Blackwell Science Ltd.
    Journal of neurochemistry 73 (1999), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract : DNA fragmentation, an early event in neuronal death following traumatic brain injury, may be triggered by the 40-kDa subunit of DNA fragmentation factor (DFF40). DFF40 is typically bound to the 45-kDa subunit of DFF (DFF45), and activation of DFF40 may occur as a result of caspase-3-mediated cleavage of DFF45 into 30-and 11-kDa fragments. In this study, the intracellular distribution of DFF45 and DFF40 was examined following lateral fluid percussion brain injury of moderate severity (2.4-2.7 atm) in male Sprague-Dawley rats. In the cytosolic fraction (S1) of the injured cortex at 2 and 24 h postinjury, significant decreases in the intensities of DFF45-like proteins at 45- and 32-kDa bands and a concomitant increase in the 11-kDa bands were observed (p 〈0.05 vs. uninjured controls). A significant decrease in the intensities of the 32-kDa band in the nuclear (P1) fraction of the injured cortex was observed at 30 min and 2 h postinjury (p 〈 0.01). Concomitantly, a decrease in DFF40 was observed in the cortical S1 fraction at 2 and 24 h (p 〈 0.05) and in the P1 fraction at 30 min and 2 h postinjury (p 〈 0.01). In the hippocampus, DFF45 decreased at 30 min in the P1 and 2 h in the S1 fraction (p 〈0.05) and recovered by 24 h postinjury, whereas DFF40 was significantly decreased in the S1 and increased in the P1 fraction at both 2 and 24 h (p 〈 0.01), which indicated a translocation of DFF40 from cytosol to nucleus. These data are the first to demonstrate that changes in DFF proteins occur after brain trauma and suggest that these changes may play a role in apoptotic cell death via caspase-3-DFF45/DFF40-DNA cleavage observed following traumatic brain injury.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1999.0731650.x
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  • 4
    Electronic Resource
    Electronic Resource
    TUNEL-positive staining of surface contusions after fatal head injury in man (2000)
    Springer
    Acta neuropathologica 100 (2000), S. 537-545 
    Details
    ISSN: 1432-0533
    Keywords: Key words Human traumatic brain injury ; TUNEL staining
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In frontal lobe contusions obtained post mortem from 18 patients who survived between 6 h and 10 days after head injury, DNA fragmentation associated with either apoptotic and/or necrotic cell death was identified by the terminal deoxynucleotidyl transferase-mediated biotinylated deoxyuridine triphosphate nick end labelling (TUNEL) histochemical technique. Additional histological techniques were also used to identify regional and temporal patterns of tissue damage. TUNEL-positive cells were present in both the grey and white matter of the contusion, where they peaked in number between 25 and 48 h, and were still identifiable at 10 days post injury. Fewer TUNEL-positive cells were observed in grey than in white matter; and most TUNEL-positive neurons in the grey matter demonstrated the morphological features of necrosis. However, the morphology of some TUNEL-stained neurons, and of TUNEL-stained oligodendroglia and macrophages in white matter was suggestive of apoptosis. Apoptosis was not seen in age- and sex-matched controls, none of whom had died from intracranial pathology or had pre-existing neurological disease. These findings suggest that multiple cell types in frontal lobe contusions exhibit DNA fragmentation and that both necrosis and apoptosis are likely to contribute to post-traumatic pathology. These findings provide further evidence that the observations made in animal models of traumatic brain injury have fidelity with clinical head injury.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010000222
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  • 5
    Electronic Resource
    Electronic Resource
    Fatty acid oxidation and myocardial phospholipase A2 activity (1989)
    Springer
    Molecular and cellular biochemistry 88 (1989), S. 155-159 
    Details
    ISSN: 1573-4919
    Keywords: phospholipase A2 ; fatty acids ; oxidation ; suppression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Summary Cis-unsaturated fatty acids, but not saturated fatty acids, inhibited phospholipase A2 activity (PLA2) in vitro, and may function as endogenous suppressors of lipolysis. To probe the possible role of lipid peroxidation in the regulation of myocardial lipid catabolism, a neutral-active and Ca2+-dependent PLA2 was extracted from rat heart and was partially purified by sulfopropyl cation exchange chromatography. Myocardial PLA, activity was inhibited in a dose-dependent manner by oleic, linoleic, linolenic, and arachidonic acids; the IC50 for arachidonic acid was approx 65 μM. Palmitic acid was not inhibitory. When arachidonic acid was incubated at 37°C, exposed to air, there was a time- and pH-dependent peroxidation of the arachidonic acid as monitored by turbidity, thiobarbituric acid reactivity, and thin layer chromatography. Peroxidation was increased as the pH was lowered from 7.5 to 4.5, and was accompanied by a decrease in PLA2 inhibitory potency. Thus, arachidonate incubated for 24 hours at pH's 4.5, 6.0 and 7.5 lost 84%, 32%, and 20% respectively, of its inhibitory potency. Therefore, in vitro acidosis promotes the oxidation of cis-unsaturated fatty acids and relieves their inhibitory or suppressive activity toward PLA2s. Increased lipid peroxidation of unesterified unsaturated fatty acids during acidosis may therefore promote lipolysis observed during myocardial ischemia and reperfusion injury.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223437
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