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Query: UMLS:C0036572 (seizures)
 80,221 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Experimental seizures were induced in mice by application of 50 mA for 0.2 sec via corneal electrodes. The reproducible conclusive behavior was characterized by a sequence of 2 sec of tonic flexion, 13 sec of tonic extension, and 8 sec of clonus followed by a postictal depressive stage. The animals were frozen and tissues were prepared for analysis according to Lowry and Passonneau [Lowry, O. H. & Passonneau, J. V. (1972) A Flexible System of Enzymatic Analysis (Academic, New York)]. Freeze-dried samples (1-10 ng) of pyramidal cell bodies and adjacent neuropil from the parietal cortex and of Purkinje cell bodies and adjacent neuropil from the cerebellum were analyzed for glucose, ATP, and P-creatine (0.01-0.05 pmol). There were marked decreases in these energy stores after the maximal electroshock in three of the areas examined. In the Purkinje cell bodies, however, the metabolic stress was dampened; glucose concentrations decreased, but the levels of ATP were maintained and, to a lesser extent, those of P-creatine. The results indicate that the output from the Purkinje cells is less than in the other regions examined in the excitable stages of the convulsion. The lesser energy debt probably reflects lower energy demand as well as a lower discharge intensity. The fact that Purkinje cells are spared from the metabolic stress imposed on other regions may be a partial explanation of the seizure activity. A diminished output from the Purkinje cells could be a situation that permits cortical convulsive activity.
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PMID:Sparing of metabolic stress in Purkinje cells after maximal electroshock. 28 34

Sustained, generalized seizure activity was induced in anaesthetized (70% N2O), paralyzed and artifically ventilated rats by i.p. DL-homocysteine thiolactone in a dose of 11 mmol/kg. Epileptic discharges in the EEG were accompanied by marked perturbation of tissue metabolites. There was a fall in phosphocreatine concentration to 40% of control but only moderate changes in adenine nucleotides, a marked rise in lactate concentration, and a pronounced increase in the lactate/pyruvate ratio. Excessive amounts of dihydroxyacetone phosphate (and glyceraldehyde phosphate) accumulated, indicating that depletion of NAD+ occurred. There was marked accumulation of ammonia, glutamine and alanine, and reduction in glutamate and aspartate concentrations. Administration of a subconvulsive dose of homocysteine (7.5 mmol/kg) gave rise to changes in ammonia and amino acids, qualitatively similar to those occurring during seizures. It is concluded that although changes in the metabolites of the energy reserve were mainly caused by the induced seizures, those affecting amino acid concentrations were significantly influenced by accumulation of ammonia, secondary to metabolism of injected homocysteine. Cerebral blood flow (CBF) and oxygen utilization (CMRO2) were measured during sustained seizures. CMRO2 rose to 150% of control, with a corresponding increase in CBF.
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PMID:Cerebral metabolic and circulatory changes in the rat during sustained seizures induced by DL-homocysteine. 50 26

To determine the relationship between brain energy metabolites and neurologic status after ischemia-hypoxia, we measured cortical tissue levels of adenosine triphosphate (ATP), phosphocreatine, and lactate. Rats with permanent unilateral carotid occlusion were exposed to 5, 10, and 15 min of hypoxic atmosphere (FIO2 0.048) and, to examine metabolic restitution, 60 min after recovery in rats exposed to the same hypoxic mixture for 15 min. At 5 and 10 min of hypoxia, there were significant reductions in phosphocreatinine and elevations in tissue lactate, but only after 15 min of hypoxia, did ATP levels significantly decrease. By 60 min after recovery, phosphocreatinine values returned to the normal range, ATP values to 15% less than normal, and tissue lactate toward normal. In parallel survival studies, neurological status was examined following hypoxic exposure (PaO2 18 to 19 torr) for 5 an 10 min. Evidence for neurological injury in the form of posthypoxic seizures occurred at a point in time preceding significant changes in brain tissue ATP level. Since injury occurs prior to ATP reduction, changes in brain tissue ATP level may not be an appropirate endpoint for determining brain tissue injury in hypoxia.
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PMID:Cerebral energy metabolite levels and survival following exposure to low inspired oxygen concentration. 72 89

The effect of sodium cyanate (25, 50, 75, and 100 mg/kg body weight i.p. daily for 10 days) upon cerebral metabolism and the EEG of Wistar rats was studied. This treatment resulted in a dose-related carbamylation of hemoglobin and left shift in the oxygen dissociation curve. Animals receiving the highest dose of cyanate developed a significant systemic metabolic acidosis. In brain there was dose-dependent decrease in phosphocreatine, TCO2 and cytoplasmic NADH/NAD+ ratio, reflecting the calculated drop in intracellular pH. Glucose levels were elevated despite a normal calculated energy charge, which suggests a balanced slowing of the energy-producing and energy-utilizing systems. The higher doses of cyanate produced spontaneous seizure activity on the EEG.
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PMID:Effects of high-dose cyanate upon cerebral energy metabolism of the rat. 120 41

Magnetic resonance spectroscopy (MRS) is a flexible tool with real clinical utility. Examples from our experience in over 250 cases of clinical proton MRS are presented. Shorter echo time and reproducible water suppression increases the number of metabolites which can be detected and identified. Case reports illustrate the significance of altered ratios of N-acetylaspartate, choline, total creatine, myo-inositol, glutamate, glutamine, lactate, glucose, ketones, and, as an incidental finding, ethanol. Significant new information has resulted by applying proton MRS in chronic hepatic encephalopathy, diabetes mellitus and severe hypoxic encephalopathy ('near-drowning'). Potentially useful measurements have been made in normal brain maturation, ethanol related diseases, dementia (normal-pressure hydrocephalus), urea cycle defect and neuronal disease presenting as seizures. Metabolite imaging, particularly with proton, is clinically valuable, documenting the heterogeneity of biochemical disorders in seemingly focal lesions. A new method of specific 31-phosphorus--phosphocreatine imaging provides information in partially denervated skeletal muscle and is expected to have applications in brain.
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PMID:Clinical tools for the 90s: magnetic resonance spectroscopy and metabolite imaging. 156 13

31-P magnetic resonance spectroscopy (MRS) allows noninvasive measurements of cerebral phosphorus compounds: ATP, phosphocreatine (PCr), inorganic phosphate (Pi), phosphomonoesters (PME) and phosphodiesters (PDE). In this paper we reported our MRS data from the brains of infants with intrauterine growth retardation, respiratory distress syndrome, neonatal seizures or neonatal asphyxia, and discussed the possibilities to prevent brain damage due to these perinatal troubles.
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PMID:[Metabolic kinetics in the brains in infants with IUGR, respiratory distress syndrome, seizures and asphyxia]. 156 50

We performed localized 31P nuclear magnetic resonance (NMR) 1H-image-guided in vivo spectroscopy to study regional high-energy phosphate levels in the brains of normal controls and in patients with intractable unilateral temporal lobe epilepsy. We did not observe differences in intracellular pH between controls and patients. The phosphocreatine/inorganic phosphate ratio was reduced by 50% in the epileptogenic temporal lobe compared with controls (p less than 0.005) and by 35% when compared with the unaffected contralateral temporal lobe (p less than 0.05). We did not observe differences in the ratio of phosphomonoesters to phosphodiesters between controls and patients. These findings suggest that in vivo 31P NMR spectroscopy yields a distinctive interictal metabolic profile in patients with intractable unilateral temporal lobe epilepsy and may permit noninvasive lateralizing evidence of the seizure focus.
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PMID:In vivo 31P nuclear magnetic resonance spectroscopy of human temporal lobe epilepsy. 164 Nov 55

The hippocampus exhibits a post-ictal phenomenon in which it is unresponsive to further stimulation. It has been suggested that this loss of excitability is the basis of post-seizure amnesia. The biochemical events associated with this phenomenon are unclear. In the present study, energy metabolites were measured in the stratum oriens, stratum pyramidale and stratum radiatum in rat hippocampus, and correlated with field potential recordings. Wistar rats were anesthetized and the calvarium removed. Following removal of the cortex by aspiration, the hippocampus was covered with oil, and stimulating and recording electrodes were placed. Stimulation consisted of a train of stimuli at 100 Hz (10-20 m Amps). This stimulation was found to be effective in evoking self-sustaining after-discharges and post-ictal depression. Tissues for metabolite analysis were taken from a series of controls, from animals during active self-sustaining seizures, and from animals which were totally unresponsive to further electrical stimulation. Hippocampal tissue for metabolite analysis was obtained by pouring liquid N2 on the exposed tissue, then removing the frozen tissue. Glucose, ATP, and phosphocreatine were measured in hippocampal layers of CA1 using fluorescence techniques and enzymatic cycling. Results showed that during seizure activity, glucose, ATP, and phosphocreatine were all decreased from 40-80% in the three layers of the hippocampus, whereas from 60 seconds after the onset of hippocampal shutdown, energy metabolites had returned toward normal. Thus, at a time when the hippocampus was unresponsive, energy metabolites were at control levels. These data suggest that the shutdown phenomenon occurs in the presence of adequate energy stores.
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PMID:Energy metabolism in rat hippocampus during and following seizure activity. 174 67

The purpose of these experiments was to determine whether flurothyl-induced status epilepticus causes progressive decline of brain high-energy phosphates and progressive increase in brain lactate in neonatal dogs who are paralyzed and oxygenated. In vivo 31P nuclear magnetic resonance spectroscopic measurements showed that the fall in brain pH occurred early in the course of seizure. The decline in phosphocreatine was more gradual, i.e. 50% reduction, during the 1st h of seizure. There was no reduction in ATP during the 3 h of status epilepticus. In vivo 1H nuclear magnetic resonance measurement of brain lactate disclosed a steep rise that stabilized by 60 min. Brain and blood lactate were closely related during the initial phase of seizure, suggesting rapid efflux of lactate from brain or systemic production of lactate. Blood lactate exceeded brain lactate after 1 h of status epilepticus. The new steady state for cerebral phosphocreatine and lactate during status epilepticus was achieved much more slowly during neonatal status epilepticus than has been reported during status epilepticus in the adult experimental animal. The lack of change in ATP during 3 h of seizure indicates that brain energy state is not radically altered during prolonged seizure if oxygenation is maintained.
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PMID:Brain energy state and lactate metabolism during status epilepticus in the neonatal dog: in vivo 31P and 1H nuclear magnetic resonance study. 201 58

The cerebral protective effect of eptazocine, an opioid mu-antagonist-kappa-agonist, was investigated using mice and rats subjected to ischemia. 1) Decapitation or concussive head injury (20 g, 30 cm)-induced ischemia in mice: Eptazocine (3,10 mg/kg) prolonged the gasping duration or the survival time in a dose-dependent manner. 2) Ischemic brain edema induced by bilateral carotid arterial occlusion (BLCO) in rats: Administration of eptazocine just after BLCO treatment significantly prevented the incidence of ischemic seizures, lethality and an increase in cerebral water content. 3) Acute ischemic changes in cerebral energy metabolism in mice: 2-min BLCO treatment decreased the cerebral contents of phosphocreatine and ATP, and it increased the contents of AMP and lactate, resulting in a 34% decrease in energy charge potential and an increase in lactate/pyruvate ratio. Such changes were improved by eptazocine (3, 10 mg/kg) and ethylketocyclazocine (3 mg/kg), a kappa-agonist. 4) Respiratory function in mouse brain mitochondria preparations: Eptazocine increased the State 3 respiration and respiratory control index (RCI:State 3/State 4), and it prevented a decrease in RCI induced by 3-min ischemia. These results suggest that eptazocine may improve cerebral ischemic disorders through an activation and/or protection of mitochondrial energy-producing systems.
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PMID:[Protective effect of eptazocine, a novel analgesic, against cerebral ischemia in mice and rats]. 205 80


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