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PubMed1983

The occurrence of two hepatic microsomal sites for amobarbital hydroxylation.

Amobarbital metabolism in human liver and in rat liver, lung, kidney, and small intestine was measured in vitro using thin-layer chromatography (TLC) for separation of metabolites generated from incubation with [2-14C]amobarbital. Formation of 3'-hydroxyamobarbital (C-OH) occurred primarily in the liver. The kinetics of C-OH formation by rat liver microsomes or isolated hepatocytes could be described by a Michaelis-Menten model incorporating two metabolic sites, one characterized by high-affinity and low-velocity constants (Km = 0.054 +/- 0.012 mM, Vmax = 16.89 +/- 4.27 nmol C-OH x g liver-1 x min-1), the other by low-affinity and high-velocity (Km = 0.679 +/- 0.097 mM, Vmax = 66.0 +/- 5.41 nmol C-OH x g liver-1 x min-1). The kinetic parameters of the high-affinity site differed significantly between whole cells and homogenates. Pretreatment with phenobarbital for 3 days induced only the high-affinity site. Quantitation of C-OH formation in four human liver samples from several sources showed that metabolism may conform to the two-site model observed in rat liver.

Amobarbital↗

PubMed1988

Narcosuggestion in chronic conversion symptoms using combined intravenous amobarbital and methylphenidate.

Five patients with chronic conversion symptoms were treated with narcoanalysis and narcosuggestion using combined methylphenidate and amobarbital. The combination of methylphenidate and amobarbital proved useful because methylphenidate antagonized sedation and allowed optimal patient cooperation. In four cases recovery of neurological function was obtained in the first or second interview and subsequently improved with practice and positive feedback. In each instance recovery of neurological function during a narcoanalytic interview confirmed the diagnosis of a conversion reaction. The narcoanalytic interview also confirmed or uncovered important psychopathology and psychodynamics which permitted more accurate treatment of the underlying psychiatric disorders.

Adult↗

PubMed2003

Memory assessment during the intracarotid amobarbital procedure: influence of injection order.

OBJECTIVE: To analyze, in patients with unilateral regional epilepsy, the influence of intracarotid amobarbital injection order on the level of recognition memory, with both injections performed within approximately half an hour, when the order was varied by a first injection into either the epileptogenic or the nonepileptogenic hemisphere. METHODS: Of a series of 74 consecutive intracarotid amobarbital procedures (IAP), 61 valid bilateral tests were extracted for analysis. The protocol was changed from a congruent sequence (epileptogenic hemisphere injected first; n = 32) to an incongruent sequence (nonepileptogenic hemisphere injected first; n = 29). Memory was quantified by the percentage of presented items recognized before the recovery of full motor power (corrected for guessing). RESULTS: The congruent group showed a poorer recognition percentage after injection into the nonepileptogenic hemisphere than after injection into the epileptogenic hemisphere. The incongruent group had a similar recognition percentage after both injections. This was especially apparent in patients with a right epileptogenic hemisphere. CONCLUSIONS: The commonly used congruent injection order leads to a poorer recognition by the epileptogenic hemisphere than the nonepileptogenic hemisphere. This relation cannot be found with an incongruent sequence. The results raise doubts about the internal validity of the IAP in describing isolated hemispheric memory functions.

Adult↗

PubMed1986

Memory for objects presented soon after intracarotid amobarbital sodium injections in patients with medically intractable complex partial seizures.

We evaluated the abilities of 36 patients with intractable temporal lobe epilepsy and left hemisphere dominance for language to later recognize objects presented in the confusional phase after left intracarotid amobarbital injection. Eighteen of 24 patients with left, but only 4/12 with right, temporal lobe epilepsy recognized at least two-thirds of objects during a post-test. These results demonstrate that the initial muteness and apparent confusion after amobarbital injection do not prohibit the formation of new memories; this gives further support to the idea that consciousness can be retained despite transient disruption of function of the language-dominant hemisphere.

Adolescent↗

PubMed1990

Visual neglect during intracarotid amobarbital testing.

The unilateral suppression of hemispheric function by sodium amobarbital may result in hemispatial visual neglect, as measured by performance on a random letter cancellation task. Our study not only investigates this hypothesis but also attempts to identify more precisely the anatomic locus of control for directed attention to extrapersonal space by correlating scanning performance with EEG activity. Forty-eight consecutive patients with epilepsy underwent preoperative intracarotid amobarbital tests. The results indicated that disruption of scanning and contralateral neglect occurred only after right-hemisphere suppression and seemed specifically related to changes in right frontal lobe EEG activity. This pattern of performance held not only for right-handed subjects, but also for those who were left-handed, and even for those who had right-hemisphere language dominance.

Adolescent↗

PubMed1992

Intracranial EEG study of brain structures affected by internal carotid injection of amobarbital.

Hippocampal function, considered critical in memory processing, is supposedly tested in the intracarotid sodium amobarbital (ISA) procedure; however, since the hippocampus is not completely irrigated by the internal carotid artery, some believe the procedure may be invalid for memory testing. We quantified delta activity in intracerebral EEGs during ISA tests. There was increased delta in ipsilateral structures as follows: amygdala (6.4 minutes), anterior hippocampus (7.2), middle hippocampus (7.4), temporal neocortex (9.1), frontal lobe (8.4), central/parietal area (11.0), and occipital lobe (9.7). Contralateral structures usually (> 64%) showed increased delta lasting 4 to 5 minutes. The ipsilateral hippocampus had delta waves in over 90% of injections. We conclude that the hippocampus is clearly affected by the ISA injection. We argue that the slow waves may not be caused by a direct effect of the drug, but rather by a functional deafferentation due to the profound inactivation of structures surrounding the hippocampus. Similarly, slow waves contralateral to injection may be caused by sudden removal of neuronal input from the regions receiving the amobarbital.

Amobarbital↗

PubMed1993

Material-specific memory in the intracarotid amobarbital procedure.

We examined material-specific memory in 45 left hemisphere language dominant patients with temporal complex partial seizures (24 right, 21 left) during the intracarotid amobarbital procedure (IAP) by showing eight cards displaying two line drawings of common objects, two printed words, one colored shape, one math expression, one face, and one abstract shape following amobarbital injection (mean = 109.9 mg). We assessed delayed recall and recognition following clearing. Patients with right foci recognized significantly fewer verbally mediated stimuli (words, object drawings, colored shape) with left than with right injection. Patients with left foci recognized a nonverbal stimulus (abstract shape) more poorly following right versus left injection. Discriminant function analysis lateralized 85% of the sample from memory predictors, upheld to 81% on crossvalidation. Material-specific memory remains intact in the hemisphere contralateral to a seizure focus, but wider representation may occur for stimuli normally dominant for the hemisphere with the seizure focus. The IAP significantly lateralizes a seizure focus with use of both types of stimuli.

Amobarbital↗

PubMed1998

Right hemisphere speech perception revealed by amobarbital injection and electrical interference.

OBJECTIVE: To investigate the right hemispheric speech perception capabilities of an adult right-handed patient with seizures. METHODS: Consecutive, unilateral, intracarotid sodium amobarbital injections and left hemispheric electrical interference mapping were used to determine lateralization and localization of speech perception, measured as syllable discrimination. RESULTS: Syllable discrimination remained intact after left and right intracarotid sodium amobarbital injections. Language otherwise strongly lateralized to the left hemisphere. Despite evidence of bilateral speech perception capabilities, electrical interference testing in the left posterior temporal lobe impaired syllable discrimination. CONCLUSIONS: The results suggest a functionally symmetric, parallel system in the adult brain with preferential use of left hemispheric pathways for speech perception.

Adult↗

PubMed1970

Rate-dependent effects of drugs: modification by discriminative stimuli of the effects of amobarbital on schedule-controlled behavior.

Food-deprived pigeons responded under a 10-min fixed-interval schedule of food presentation. During even-numbered minutes of the schedule, the discriminative stimuli were the same as those present when food was delivered. During odd-numbered minutes there was either a change in keylight color or a change in overhead illumination, either for the entire duration of the odd-numbered minutes, or for 3-sec after each response. Responding during even-numbered minutes showed the usual pattern of positive acceleration; responding during odd-numbered minutes was similarly graded, but rates were much lower. The response-rate-increasing effects of amobarbital were inversely related to control rates of responding for both even- and odd-numbered minutes. However, when the stimulus change during odd-numbered minutes was either keylight color or a change from a darkened to a brightly illuminated chamber, increases in responding were considerably less than predicted on the basis of the effects on responding during even-numbered minutes. When the stimulus change was from a darkened to a dimly illuminated chamber, control rates of responding changed little, but increases in responding during odd-numbered minutes after amobarbital were considerably greater, and of the approximate order expected on the basis of control rate.

Amobarbital↗

PubMed1982

Change in auditory asymmetry with amobarbital: evidence of cerebral pharmacological asymmetry?

Eleven right-handed subjects were administered a dichotic listening test to assess cerebral hemispheric dominance, both under a drug-free condition and following systemic injection of the barbiturate, amobarbital. The finding of increased right ear advantage during the drug period reflects increased left cerebral dominance, and suggests that amobarbital may have an asymmetric, pharmacological effect on the two cerebral hemispheres.

Adult↗

PubMed2006

Dissociated expressive and receptive language functions on magnetoencephalography, functional magnetic resonance imaging, and amobarbital studies. Case report and review of the literature.

Dissociated language functions are largely invalidated by standard techniques such as the amobarbital test and cortical stimulation. Language studies in which magnetoencephalography (MEG) and functional magnetic resonance (fMR) imaging are used to record data while the patient performs lexicosemantic tasks have enabled researchers to perform independent brain mapping for temporal and frontal language functions (MEG is used for temporal and fMR imaging for frontal functions). In this case report, the authors describe a right-handed patient in whom a right-sided insular glioma was diagnosed. The patient had a right-lateralized receptive language area, but expressive language function was identified in the left hemisphere on fMR imaging- and MEG-based mapping. Examinations were performed in 20 right-handed patients with low-grade gliomas (control group) for careful comparison with and interpretation of this patient's results. In these tests, all patients were asked to generate verbs related to acoustically presented nouns (verb generation) for fMR imaging, and to categorize as abstract or concrete a set of visually presented words consisting of three Japanese letters for fMR imaging and MEG. The most prominent display of fMR imaging activation by the verb-generation task was observed in the left inferior and middle frontal gyri in all participants, including the patient presented here. Estimated dipoles identified with the abstract/concrete categorization task were concentrated in the superior temporal and supramarginal gyri in the left hemisphere in all control patients. In this patient, however, the right superior temporal region demonstrated significantly stronger activations on MEG and fMR imaging with the abstract/concrete categorization task. Suspected dissociation of the language functions was successfully mapped with these two imaging modalities and was validated by the modified amobarbital test and the postoperative neurological status. The authors describe detailed functional profiles obtained in this patient and review the cases of four previously described patients in whom dissociated language functions were found.

Adult↗

PubMed1997

The effect of early versus late onset of temporal lobe epilepsy on hemispheric memory laterality: an intracarotid amobarbital procedure study.

Thirty-three temporal lobe epilepsy (TLE) patients, 19 left TLE and 14 right TLE, underwent an intracarotid amobarbital procedure. For each patient, hemispheric memory laterality was determined by measuring the relative magnitude of recognition memory following left versus right hemisphere injection of sodium amobarbital. The patients were divided into early and late seizure onset groups, based on the median age (13 yrs) of seizure onset of the total sample. Early-onset left TLE was associated with a greater tendency toward right hemispheric representation of both verbal and visual memory compared with late-onset left TLE. Early-onset right TLE was associated with a greater tendency toward left hemispheric representation of visual, but not verbal, memory compared with late-onset right TLE. These findings indicate that interhemispheric plasticity for memory is greater in early than in late life, bidirectional, and at least partially material-specific.

Adolescent↗

PubMedDate not supplied

N-hydroxyamobarbital: the second major metabolite of amobarbital in man.

After oral administration of 14C-labeled amobarbital to healthy subjects, most of the radioactivity was recovered in urine and only 4-5% in feces over a period of 6 days. No unchanged amobarbital was excreted. Two major metabolites were found and isolated. One was 3'-hydroxyamobarbital, which has been previously identified by Maynert. The second could be identified as N-hydroxyamobarbital on the basis of its spectral and chemical properties.

Amobarbital↗

PubMed1991

Effects of amobarbital on pterins and dinucleotides contents in rat brain.

The effects of amobarbital (50 mg.kg-1 ip) on the brain concentrations of biopterin, pterin, reduced nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) were studied by a reverse phase high performance liquid chromatography with fluorescent detector. Amobarbital increased FAD concentrations in 5 brain areas and pterin concentration in the cortex, but decreased biopterin concentrations in the cortex and hippocampus.

Amobarbital↗

PubMed1979

Single alternation with water reward:effects of sodium amobarbital on two strains of rats selectively bred for high and low emotionality.

The action of sodium amobarbital is studied during the patterning effect in rats selectively bred for low and high emotionality. The drug disrupts patterned running in the goal section of the alley in Maudsley non-reactive but not in Maudsley reactive rats for the last five trial-pairs. Sodium amobarbital also affects the behavior of these strains in a differential manner, in start and run sections, during the first trial-pair. The results show that a function-related physiological change has taken place in the Maudsley strains of rats.

Amobarbital↗

PubMedDate not supplied

[Lormetazepam and amobarbital in the treatment of insomnia in psychiatric outpatients. A controlled study].

During a double-blind clinical study, a new hypnotic benzodiazepine, lormetazepam (Wy 4082), was compared at a fixed dose of 1 mg to sodium amobarbital at a fixed dose of 100 mg for the treatment of moderate insomnia in 2 groups of 25 psychiatric outpatients. The medication was given at bedtime and the duration of the study was limited to 2 weeks. The quality of sleep was evaluated by the patient after the first night and at the end of the first and second week and by investigator at the end of the 2 weeks trial. The two products appeared effective on global assessment, but with an advantage in favour of lormetazepam: earlier onset of sleep and excellent acceptability on the final evaluation. Fifty two per cent of patients treated with amobarbital had side effects, mainly hangover and sedation during the morning, while only one patient treated with lormetazepam complained of headaches in the morning.

Adult↗

PubMed1978

Amobarbital metabolism in man: N-glucoside formation.

N-Hydroxyamobarbital, the compound previously proposed as the second major metabolite of amobarbital was synthesized. The metabolite was shown not to be N-hydroxyamobarbital. NMR and MS analyses on the metabolite suggested it could be a derivative of N-beta-D-glucopyranoside. This proposed structure was confirmed by comparison with the spectral data of synthetic amobarbital-N-methyl-N-2,3,4,6-tetraacetyl-beta-D-glucopyranoside.

Amobarbital↗

PubMed1993

[The selective amobarbital test in epileptology].

Epileptic foci in the frontal or parieto-occipital cortex often cause epileptiform EEG changes in both hemispheres. Therefore, delineation of the primary epileptogenic area, which is necessary for epilepsy surgery, is not possible by electrophysiological methods. A temporary inactivation of the epileptogenic area by a selective injection of the short-acting barbiturate amobarbital (selective amobarbital test, SAT) can prove the relation between generalized EEG changes and a circumscribed epileptogenic area. The SAT may also be used for evaluation of the risk for additional functional deficits after epilepsy surgery in certain brain areas. During temporary inactivation of the brain area to be resected, the function of the motor system, speech and memory can be tested.

Amobarbital↗