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- Agardh, Carl-David, et al.
(författare)
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Hypoglycemic brain injury. I. Metabolic and light microscopic findings in rat cerebral cortex during profound insulin-induced hypoglycemia and in the recovery period following glucose administration
- 1980
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Ingår i: Acta Neuropathologica. - 1432-0533. ; 50:1, s. 31-41
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 2. |
- Agardh, Carl-David, et al.
(författare)
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Hypoglycemic brain injury: metabolic and structural findings in rat cerebellar cortex during profound insulin-induced hypoglycemia and in the recovery period following glucose administration
- 1981
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Ingår i: Journal of Cerebral Blood Flow and Metabolism. - 1559-7016. ; 1:1, s. 71-84
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Tidskriftsartikel (refereegranskat)abstract
- Previous results have shown that severe, prolonged hypoglycemia leads to neuronal cell damage in, among other structures, the cerebral cortex and the hippocampus but not the cerebellum. In order to study whether or not this sparing of cerebellar cells is due to preservation of cerebellar energy stores, hypoglycemia of sufficient severity to abolish spontaneous EEG activity was induced for 30 and 60 min. At the end of these periods of hypoglycemia, as well as after a 30 min recovery period, cerebellar tissue was sampled for biochemical analyses or for histopathological analyses or for histopathological analyses by means of light and electron microscopy. After 30 min of hypoglycemia. the cerebellar energy state, defined in terms of the phosphocreatine, ATP, ADP, and AMP concentrations, was better preserved than in the cerebral cortex. After 60 min, gross deterioration of cerebellar energy state was observed in the majority of animals, and analyses of carbohydrate metabolites and amino acids demonstrated extensive consumption of endogenous substrates. In spite of this metabolic disturbance, histopathologic alterations were surprisingly discrete. After 30 min, no clear structural changes were observed. After 60 min, only small neurons in the molecular layer (basket cells) were affected, while Purkinje cells and granule cells showed few signs of damage. The results support our previous conclusion that the pathogenesis of cell damage in hypoglycemia is different from that in hypoxia-ischemia and indicate that other mechanisms than energy failure must contribute to neuronal cell damage in the brain.
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| 4. |
- Kalimo, H, et al.
(författare)
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Hypoglycemic brain injury. II. Electron-microscopic findings in rat cerebral cortical neurons during profound insulin-induced hypoglycemia and in the recovery period following glucose administration
- 1980
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Ingår i: Acta Neuropathologica. - 1432-0533. ; 50:1, s. 43-52
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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