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

The epileptogenic action of parenteral penicillin was studied in turtles with electrodes chronically implanted in both cerebral hemispheres. Penicillin was administered intraperitoneally at doses of 200,000 to 1,600,000 IU/kg. Doses higher than 600,000 IU/kg caused the appearance on the electrocorticogram of bilateral sharp waves or biphasic spikes, sometimes more pronounced in one hemisphere. These events were often accompanied by clonic activity of the neck muscles and mouth movements in an epileptic automatism. Intravenous penicillin (200,000 to 1,000,000 IU/kg) also evoked changes of the basic pattern of the electrocorticogram. Doses up to 350,000 IU/kg induced bilateral sharp waves and/or spikes sometimes accompanied by the seizures described in item 2. Doses above 400,000 IU/kg produced bilateral synchronous spike or polyspike discharges with a clonic-tonic seizure pattern. The same dose of penicillin induced more marked changes in the electrocorticogram when injected intravenously than intraperitoneally. Since larger doses of parenteral penicillin were required to evoke epileptic activity in turtles than in cats, the present results are consistent with the concept that the brain of phylogenetically lower animals is less susceptible to epileptogenic agents than the brain of higher animals.
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PMID:Electrocorticographic and behavioral features of turtle parenteral penicillin epilepsy. 380 29

Neurologic complications continue to occur in approximately 30 per cent of all patients with infective endocarditis and represent a major factor associated with an increased mortality rate in that disease. Of these complications, cerebral embolism is the most common and the most important, occurring in as many as 30 per cent of all patients, most of whom ultimately die. Emboli that are infected also account for all the other complications (mycotic aneurysm, meningitis or meningoencephalitis, brain abscess) that may develop. Emboli are more common in patients with mitral valve infection and in those infected with more virulent organisms. Mycotic aneurysms (often preceded by an embolic event) occur more frequently and earlier in the course of acute endocarditis, rather than later, which is more common in the course of subacute disease. The management of a cerebral mycotic aneurysm depends on the presence or absence of hemorrhage, its anatomic location and the clinical course. Healing can occur during the course of effective antimicrobial therapy and thus will preclude the need for automatic surgery in all angiographically demonstrated aneurysms. The indication for surgical intervention must be evaluated on an individual basis. Meningitis is usually purulent when associated with virulent organisms, but the CSF may present an aseptic formula when associated with subarachnoid hemorrhage or multiple microscopic embolic lesions, infected or otherwise. Macroscopic brain abscesses are rare, but multiple microscopic abscesses are not uncommon in patients with acute endocarditis due to virulent organisms. Seizures are not uncommon in patients with infective endocarditis. Focal seizures are more commonly associated with acute emboli, whereas generalized seizures are more commonly associated with systemic metabolic factors. Penicillin neurotoxicity should be considered in seizure patients with compromised renal function who are receiving high doses of penicillin. The CSF tends to reflect the nature of the infecting organism rather than the nature of the neurologic complication, except when hemorrhage is present. Endocarditis due to virulent organisms, such as Staphylococcus aureus, is usually associated with a purulent CSF formula, whereas non-virulent organisms, such as "viridans" streptococci, usually have aseptic or normal CSF formulas.
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PMID:Neurologic complications of infective endocarditis. 383 85

This investigation was carried out to clarify the mechanisms for production of different seizure threshold. To study this problem changes of a single cell activity were examined by means of penicillin iontophoretical application to a single cell of both low seizure threshold hippocampus and the high seizure threshold olfactory bulb, and also topical application to the surface of hippocampus and olfactory bulb. Penicillin was applied iontophoretically using five barrel glass micropipettes. Extracellular recordings from 58 hippocampal pyramidal cells and 68 olfactory bulb mitral cells were analyzed. Penicillin increased the firing rate in most of both hippocampal pyramidal and olfactory bulb mitral cells. This suggests that penicillin finally had an excitatory effect on both cells. The results from the experiments of intermittent and continuous GABA application on a cell during penicillin iontophoresis revealed that GABA inhibitory action was reduced by penicillin in both cells. A progressively shortened duration of the post-discharge inhibition during penicillin iontophoresis also suggested that penicillin may reflect a decrease of GABA inhibitory action. No obvious seizure activity and/or no change of firing pattern were observed even after long penicillin iontophoresis. There was no significant different responses to penicillin iontophoresis in the hippocampus and the olfactory bulb single cell. Extracellular activity from 64 hippocampal pyramidal cells and 32 olfactory bulb mitral cells was recorded. The effects of penicillin topical application on single cell function were examined. From hippocampus surface, paroxysmal activity begun to appear within 6 min after topical application, and became more regular and stereotyped in form. The firing rate initially decreased in the majority of cells, with no increase prior to interictal or ictal events. The unit responses to both intermittent and continuous GABA iontophoresis was suppression in unit firing incidence, except for the burst patterns associated with the surface interictal or ictal discharges. Post-discharge inhibition was not significantly different either before or after the onset of the surface interictal discharges. These results indicate the firing rate and inhibitory function of the hippocampal pyramidal cells were not significantly changed during and following the development of interictal and/or ictal epileptiform activity. Olfactory bulb surface activity was not significantly changed and no epileptiform activity was observed even several hours after topical penicillin application.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Experimental studies on different thresholds for epileptiform activity. 609 5

Penicillin application to the rat brain motor cortex resulted in appearance of interictal discharges and seizures. After diazepam injection (2 mg/kg) a 100% increase in Na, K-ATPase activity of neuronal membranes in the epileptogenic focus was shown as compared to enzyme activity before diazepam injection. Interictal discharges and seizures changed in different ways after intramuscular injection of diazepam. The frequency and amplitude variation of interictal discharges increased but the seizures were suppressed. These effects increased with the dose of diazepam. It is suggested that the different influence of diazepam upon seizures and interictal discharges may reflect different mechanisms of these phenomena.
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PMID:[Electrical activity and Na, K-ATPase levels in an epileptic focus caused by application of penicillin to rat cerebral cortex and the effect of diazepam on them]. 625 82

Two types of intracellular activity have been found in neurons in the cortical penicillin seizure focus during an interictal spike; a prolonged depolarization (PDS) followed by hyperpolarization or predominantly hyperpolarization. In the present study of a penicillin focus we have correlated the penicillin focus location with motor behavior and the cellular physiology with cellular morphology and location. Penicillin injection at the same location in the anterior sigmoid gyrus invariably resulted in focal seizures involving the contralateral shoulder. From the locations of the myoclonus and the focus, the character of the movements and the route of seizure spread we conclude that the same pathways mediate movement produced by penicillin seizures or by electrically stimulating the same motor cortex. Intracellular recordings and dye-marking of cells in and around the seizure focus revealed that PDS neurons were located within a 3 mm radius from the site of penicillin injection. All PDS neurons either lacked well filled processes or had abnormal dendrites. Inhibited neurons were all pyramidal neurons with normal dendrites. The dendritic abnormalities observed could be important in the genesis of the PDS.
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PMID:Focal penicillin seizures--motor activity and cellular physiology and morphology. 641 52

Convulsions were induced in 20 cats by the administration of intravenous penicillin. Furosemide administered together and after penicillin failed to reduce the seizure activity. Penicillin brain concentrations were not reduced by furosemide. Penicillin induced seizures are not affected by furosemide.
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PMID:Furosemide effect on penicillin induced convulsions. 653 53

Penicillin (2-3 mg X kg-1) administered into the cisterna magna (i.c.) of dogs anaesthetized with alpha-chloralose induced a significant increase in mean blood pressure (MBP) and bradycardia, whereas intravenous injections of the same doses had negligible effects. Moreover, dogs receiving central injections of penicillin showed seizures abolished by administration of decamethonium bromide (100 micrograms X kg-1, i.v.). In urethane anaesthetized rats, intracerebroventricular (i.c.v.) injections of penicillin (0.3-3 mg X kg-1) caused dose-dependent increases in mean blood pressure while the intravenous route led to opposite effects. gamma-aminobutyric acid (GABA) (1 mg X kg-1), its agonist muscimol (2 micrograms X kg-1) and the alpha 2-adrenoceptor agonist clonidine (1 micrograms X kg-1) injected intracisternally induced hypotension and bradycardia in dogs. These effects were abolished in animals pretreated with penicillin. In rats, the same agents injected intraventricularly respectively at 0.5 mg X kg-1, 0.5 micrograms X kg-1 induced also hypotension. The effect of clonidine only, was antagonized by pretreatment with penicillin, while penicillin administered at the peak of the hypotensive effect caused by GABA or muscimol reversed it. It is suggested that penicillin acts centrally as a GABA-antagonist, and that the cardiovascular effects of clonidine seem to be mediated, at least in part, by the stimulation of a GABAergic pathway controlling the autonomic nervous system.
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PMID:Central cardiovascular action of penicillin in anaesthetized dogs and rats. 662 19

Transection of the spinal cord of the cat at a thoracic or lumbar level results, after as short a period as 12 days, in a preparation with such altered excitability that repeated natural stimulation of the dermatome just caudal to the transection site will induce, in as short a time as 3 days, seizure discharges. The trigger zone for the seizure spreads to caudal dermatomes when these caudal regions are repeatedly stimulated. The 'typical' T4-T7 seizure is a scratch reflex followed by the tonic-clonic seizure lasting for 20-30 s and ending with a scratch afterdischarge lasting for several minutes. Lower thoracic and upper lumbar seizures consist of tonic-clonic co-contractions of the muscles of the hindlegs, followed by rhythmical stepping movements lasting less than 1 min. Partial dorsal rhizotomy or local Cobalt application to the spinal cord may reduce the threshold for induction of seizure by natural stimulation and local Penicillin application to spinal cord induces seizure discharges similar to those induced by natural stimulation. Retransection of the spinal cord caudally, with elimination of the primary trigger zone, does not abolish the secondarily acquired triggers. The findings suggest that spinal circuits possess the ability to acquire new neuronal patterns of discharge and to transfer them to other more caudal segments.
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PMID:Induction of spinal seizures by natural stimulation in cats. 673 53

Penicillin administration elicited epileptiform responses whereas micropolarization (MCP) affected the epileptogenic foci in cats with indwelled electrodes and chemotrodes. Three types of experimental epilepsy models were obtained: focal petit mal seizures, adversive, and grand mal seizures. The MCP of amygdala and caudate nucleus completely suppressed all three types of seizures whereas MCP of hippocampus enhanced the pathology. Two mechanisms of seizure suppression seem to exist: the inhibitory and the activating ones.
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PMID:[Suppression of epileptiform activity by micropolarizing brain structures]. 696 22

Filter paper strips soaked in 3H-glycine solution were applied to acoustic cortex of cats, anaesthetized with Nembutal and pretreated with epileptogenic agents (Metrazol, G-penicillin, and 3-amino-pyridine) and cycloheximide. The untreated contralateral hemisphere served as control. After 1 h incubation, both cortical samples were excised simultaneously and fixed in Bouin solution for autoradiography. Incorporation was blocked by cycloheximide. There was no glycine incorporation on the penicillin-treated side, while pyramidal cells were intensively labelled in layers II-V of the mirror focus. 3-Aminopyridine produced the same result. Metrazol as convulsant proved to be far weaker than the previous two. The intensity of incorporation was significantly more intensive in the mirror focus than in the primary one. Penicillin and 3-aminopyridine, while provoking cortical seizures, seem to inhibit glycine incorporation into a neuron-specific, function-dependent protein contained by the labelled cells in the autoradiogram.
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PMID:Effect of epileptogenic agents on the incorporation of 3H-glycine into proteins in the cat's cerebral cortex. 708 39


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