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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 79 (1975), S. 265-269 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of organic chemistry 56 (1991), S. 6565-6573 
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Increasing evidence suggests that excessive activation of the calcium-activated neutral protease μ-calpain could play a major role in calcium-mediated neuronal degeneration after acute brain injuries. To further investigate the changes of the in vivo activity of μ-calpain after unilateral cortical impact injury in vivo, the ratio of the 76-kDa activated isoform of μ-calpain to its 80-kDa precursor was measured by western blotting. This μ-calpain activation ratio increased to threefold in the pellet of cortical samples ipsilateral to the injury site at 15 min, 1 h, 3 h, and 6 h after injury and returned to control levels at 24–48 h after injury. We also investigated the effect of μ-calpain activation on proteolysis of the neuronal cytoskeletal protein α-spectrin. Immunoreactivity for α-spectrin breakdown products was detectable within 15 min after injury in cortical samples ipsilateral to the injury site. The levels of α-spectrin breakdown products increased in a biphasic manner, with a large increase between 15 min and 6 h after injury, followed by a smaller increase between 6 and 24 h after the insult. No further accumulation of α-spectrin breakdown products was observed between 24 and 48 h after injury. Histopathological examinations using hematoxylin and eosin staining demonstrated dark, shrunken neurons within 15 min after traumatic brain injury. No evidence of μ-calpain autolysis, calpain-mediated α-spectrin degradation, or hematoxylin and eosin neuronal pathology was detected in the contralateral cortex. Although μ-calpain autolysis and cytoskeletal proteolysis occurred concurrently with early morphological alterations, evidence of calpain-mediated proteolysis preceded the full expression of evolutionary histopathological changes. Our results indicate that rapid and persistent μ-calpain activation plays an important role in cortical neuronal degeneration after traumatic brain injury. Our data also suggest that specific inhibitors of calpain could be potential therapeutic agents for the treatment of traumatic brain injury in vivo.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: This study investigated the temporal expression and cell subtype distribution of activated caspase-3 following cortical impact-induced traumatic brain injury in rats. The animals were killed and examined for protein expression of the proteolytically active subunit of caspase-3, p18, at intervals from 6 h to 14 days after injury. In addition, we also investigated the effect of caspase-3 activation on proteolysis of the cytoskeletal protein α-spectrin. Increased protein levels of p18 and the caspase-3-specific 120-kDa breakdown product to α-spectrin were seen in the cortex ipsilateral to the injury site from 6 to 72 h after the trauma. Immunohistological examinations revealed increased expression of p18 in neurons, astrocytes, and oligodendrocytes from 6 to 72 h following impact injury. In contrast, no evidence of caspase-3 activation was seen in microglia at all time points investigated. Quantitative analysis of caspase-3-positive cells revealed that the number of caspase-3-positive neurons exceeded the number of caspase-3-positive glia cells from 6 to 72 h after injury. Moreover, concurrent assessment of nuclear histopathology using hematoxylin identified p18-immunopositive cells exhibiting apoptotic-like morphological profiles in the cortex ipsilateral to the injury site. In contrast, no evidence of increased p18 expression or α-spectrin proteolysis was seen in the ipsilateral hippocampus, contralateral cortex, or hippocampus up to 14 days after the impact. Our results are the first to demonstrate the concurrent expression of activated caspase-3 in different CNS cells after traumatic brain injury in the rat. Our findings also suggest a contributory role of activated caspase-3 in neuronal and glial apoptotic degeneration after experimental TBI in vivo.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 41 (1983), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: This study introduces a new method for rapid freezing of the cat brain. The method employed a Styrofoam box which was fitted around the head of the animal. Liquid nitrogen was poured into the box until the head was submerged. Temperature changes in three brain sites (ventral hypothalamus, the fourth ventricle, and the corpus callosum) and levels of labile carbohydrate metabolites (glycogen, glucose, ATP, P-creatine, and lactate) in five brain regions (cortex, thalamus, midbrain, cerebellum, and pons) frozen by the box method were compared with those frozen by a conventional cup method in which liquid nitrogen was poured into a hollow Styrofoam cup placed on top of the skull. The box method shortened the time of arrival of the freezing front and improved the freezing rate. The time required to bring the tissue to -20°C was shortened, from 20 min at the ventral hypothalamus and 10–12 min at the fourth ventricle with the cup method, to 〈5 min at both sites with the box technique. Continued perfusion of brainstem prior to freezing was demonstrated. Levels of metabolites frozen by either method were similar. Lactate levels in any of the five brain regions studied by either method were not elevated, indicating no ischemic change. The shorter freezing time resulting from the box method should provide improved temporal resolution in studying dynamic metabolic changes such as those frequently observed in pathological conditions.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 8158-8162 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An analysis is presented to accurately calculate the effects of photon recycling on the minority-carrier lifetime in the active region of GaAs/Al0.3Ga0.7As double heterostructures. It is shown that the minority-carrier lifetime multiplication factor and resulting minority-carrier lifetime are dominated by multiple reflection propagation for samples with thicknesses of approximately less than 1.0 μm. The calculated results are in good agreement with previously published experimental data on the variation of the minority-carrier lifetime multiplication factor with active region thickness, indicating the usefulness of the analysis to accurately model the effects of photon recycling in transient photoluminescence measurement of thin devices. This may lead to accurate determination of the minority-carrier lifetime, diffusion coefficient, and surface recombination velocities at the levels of interest for device applications.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 1088-1090 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The minority-carrier lifetime has been measured by time-resolved photoluminescence in epitaxial films of GaAs grown by metalorganic chemical vapor deposition. The measured lifetimes in thicker devices are 4 to 6 times the theoretical or radiative lifetime. These long lifetimes are the result of photon recycling or self-generation of the self-absorbed radiation.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Psychophysiology 9 (1972), S. 0 
    ISSN: 1469-8986
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: An easily made, accurate, direct reading scale for obtaining beat-by-beat HR from paper chart EKG recordings is described for use where on-line computer analysis is not practicable, or where a check is wanted on the accuracy of the computer program.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 1326-1328 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A double-heterojunction optical thyristor is presented, that can be turned off in a few nanoseconds simply by using the anode to a negative voltage exceeding a certain threshold. Previously, nanosecond-range turn-off could only be achieved by carrier extraction via contacts to either or both of the center two thyristor layers. Our turn-off method uses a PnpN layer structure for which punch-through of the n-layer under reverse bias of the P-n diode can be reached before this diode breaks down. We thus achieve an improvement in turn-off time by about 3 orders of magnitude over traditional two-terminal thyristors.
    Type of Medium: Electronic Resource
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