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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 62 (1983), S. 87-95 
    ISSN: 1432-0533
    Keywords: Status epilepticus ; Nerve cell injury ; Bicuculline ; Rat cerebral cortex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary It was earlier shown that bicuculline-induced status epilepticus gives rise to profound acute changes in the rat cerebral cortex, i.e. edema and neuronal alterations. In the present study, we explored to what extent interruption of the seizure activity reverses the changes observed. To that end, status epilepticus of 1 and 2 h duration was induced by bicuculline before the seizures were arrested by i.v. injection of diazepam. The brain was then fixed by vascular perfusion either 5 min (1 h of seizures) or 2 h (1 and 2 h of seizures) of recovery and cerebral cortical tissue was studied by light (LM) and electron microscopy (EM). Already 5 min following the arrest of seizure activity most of the astrocytic edema had disappeared, and the number of injured neurons was clearly reduced. After 2 h of recovery, following 1 h of status epilepticus, the edema was virtually absent, and only few injured cells were found (only about 1% of the neuronal population). When recovery was instituted after 2 h of status epilepticus, numerous dark, triangular neurons were found. In the last group an adequate blood pressure could not be obtained. Therefore, the cellular alterations observed were probably not the result of the seizure activityper se. After 5 min of recovery, EM studies showed condensed, dark-staining injured neurons, similar to those previously observed in non-recovery animals. However, an increased incidence of swollen mitochondria was observed. After 2 h of recovery a few severely injured neurons remained which showed signs of progressive injury with fragmentation of the cell body.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 50 (1980), S. 31-41 
    ISSN: 1432-0533
    Keywords: Hypoglycemia ; Nerve cell injury ; Biochemistry ; Light microscopy ; Rat cerebral cortex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Profound hypoglycemia causing the disappearance of spontaneous EEG activity was induced by insulin in rats. For analysis of cerebral cortical concentrations of labile phosphates, glycolytic metabolites and amino acids, the brain was frozen in situ. For microscopic analysis of the corresponding cerebral cortical areas the brain was fixed by perfusion. Hypoglycemia with an isoelectric EEG for 30 and 60 min caused severe perturbation of the cerebral energy metabolites. After both 30 and 60 min of isoelectric EEG, two microscopically different types of nerve cell injury were seen. Type I injury was characterized by angulated, darkly stained neurons with perineuronal vacuolation, mainly affecting small neurons in cortical layer 3. Type II injured neurons, mainly larger ones in layers 5–6, were slightly swollen with vacuolation or clearing (depending on the histotechnique used) of the peripheral cytoplasm, but had no nuclear changes. Recovery was induced by glucose injection. Improvement in the cerebral energy state occurred during the 30 min recovery period even after 60 min of hypoglycemia. However, the persisting reduction in the size of adenine nucleotide and amino acid pools after 30 or 180 min recovery suggested that some cells remained damaged. In confirmation many type I injured neurons persisted during the recovery suggesting an irreversible injury. The disappearance of virtually all type II injuries indicated reversibility of these histopathological changes. The microscopic changes in hypoglycemia were different from those in anoxia-ischemia suggesting a dissimilar pathogenesis in these states despite the common final pathway of energy failure.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 50 (1980), S. 43-52 
    ISSN: 1432-0533
    Keywords: Hypoglycemia ; Nerve cell injury ; Electron microscopy ; Rat cerebral cortex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Severe hypoglycemia was induced in rats by insulin. The brain was fixed in situ by perfusion after the spontaneous EEG had disappeared for 30 or 60 min or after recovery had been induced for 30 or 180 min by glucose injection. Samples from the cerebral cortex from the area corresponding to the previous metabolic studies were processed for electron microscopy. The light-microscopic finding of two different types of nerve cell injury, reported in a preceding communication (Agardh et al. 1980), was also verified at the ultrastructural level. The type I injury was characterized by cellular shrinkage, condensation of the cell sap and nuclei, and perineuronal astrocytic swelling. No swelling of mitochondria occurred. The slightly swollen type II injured neurons showed contraction of mitochondria, disintegration of ribosomes, loss of RER, and appearance of membrane whorls, while their nuclear chromatin remained evenly distributed. No transition from one type to the other was observed. Neither type of nerve cell injury in hypoglycemia was like that commonly seen in anoxic-ischemic insults indicating a different pathogenesis in these states despite the common final pathway of energy failure. The loss of endoplasmic membranes and disintegration of ribosomes suggests that these structures might be sacrificed for energy production in the absence of normal substrates. During recovery, though, the number of type I injured neurons decreased while some of the remaining ones appeared even more severely affected, suggesting irreversible damage. Type II injured neurons were no longer seen indicating reversibility of these changes.
    Type of Medium: Electronic Resource
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