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Biomedical subjects

I Jibiki

Publications and source records attributed to I Jibiki.

At least 37 records · Page 2Linked to original sources
PubMed1993

Haloperidol-induced blockade of induction of long-term potentiation in perforant path-dentate gyrus pathway in chronically prepared rabbits.

We investigated the effects of the representative neuroleptic and dopamine receptor antagonist haloperidol (HPD) on the induction of long-term potentiation (LTP) or on the previously induced LTP in the perforant path-dentate gyrus pathway in chronically prepared rabbits. The IP HPD injection of 0.8 mg/kg blocked the induction of LTP when it was given before LTP-inducing tetanic stimulations, although this dose showed virtually no effect on the baseline control responses in the perforant path-dentate gyrus pathway to single shocks. However, neither 0.8-mg/kg nor 1.6-mg/kg HPD doses affected the previously induced LTP. The possible mechanisms underlying these results, notably the HPD-induced blockade of LTP induction, are discussed, especially in association with the inhibitory action of HPD on calmodulin-mediated events rather than dopaminergic function.

Animals↗
PubMed1993

Paradoxical GABAergic facilitation on seizure development observed from bicuculline-induced effects on visual cortical kindling at short interstimulus intervals in chronically prepared rabbits.

To investigate the influence of GABAergic function on seizure development, the effects of bicuculline, a GABAa receptor antagonist, on visual cortical and hippocampal kindling were examined in chronically prepared rabbits. Kindling-inducing stimulations were repeated at 5-min intervals. The changes in afterdischarge (AD) durations were compared before and 30 min after a low (2 mg/kg) and high dose (5 mg/kg) i.p. injection of bicuculline solution. In the visual cortical kindling group, the AD durations were markedly shortened after the low dose bicuculline injection, while bicuculline produced a prolongation of the AD durations in the visual cortical with the high dose injection and hippocampal kindling groups. The low dose bicuculline-induced inhibition of visual cortical kindling suggests facilitative GABAergic action on seizure development, while the drug-induced enhancement in the other groups reflects the well-known inhibitory GABAergic action.

Animals↗
PubMed1993

Acutely administered haloperidol has little effect on steady-state visual evoked potentials from pattern-reversal stimulations in treated schizophrenics.

The amplitude changes in steady-state visual evoked potentials (VEPs) from pattern-reversal stimulations at 30 min after an intramuscular injection of haloperidol were examined in 10 treated schizophrenics. The VEP amplitudes to hemi-field or full-field pattern-reversal stimulations with a standard check size were almost unchanged after the haloperidol injection as compared with those before the injection. However, while the VEP amplitudes to the full-field stimulations were significantly higher in the midline occipital portion than in the right occipital portion before the injection, no significant difference was observed after the injection. Further, the VEPs similarly responded to the change in the check sizes used in the full-field stimulations before and after the injection, both showing significantly lower amplitudes only at the large check size of 4.1 degrees in a visual angle than that of 1.0 degrees. These results indicate that acutely administered haloperidol has little effect on steady-state VEPs from pattern-reversal stimulations in treated schizophrenics.

Adult↗
PubMed1993

Diffuse cerebral hypoperfusion in epileptic patients observed from quantitative assessment with single photon emission computed tomography using N-isopropyl-(iodine-123)-p-iodoamphetamine.

Quantitative assessment of regional cerebral blood flow (rCBF) in the bilateral cerebral and cerebellar cortices was performed in 15 epileptic adult patients receiving chronic high-dose antiepileptic drug therapy and 22 normal volunteers matched for sex and age, using single photon emission computed tomography with N-isopropyl-(iodine-123)-p-iodoamphetamine. The entire averaged rCBF value in the epileptic patients, i.e. 52.8 +/- 13.7 ml/10 g/min (range: 25-78 ml/100 g/min), was significantly lower as compared with that in the normal subjects, i.e. 69.1 +/- 14.2 ml/100 g/min (range: 46-102 ml/100 g/min). Six of the 15 patients showed absolute rCBF values less than the minimum of the normal range, i.e. 46 ml/100 g/min, in all or most of the measured brain tissues. There was a significant correlation between the diffuse cerebral hypoperfusion and simultaneous ingestion of phenytoin and phenobarbital. The possible effects of antiepileptic drugs on rCBF are discussed.

Adult↗
PubMed1993

Probable cerebellar abnormality on N-isopropyl-(iodine-123)-p-iodoamphetamine single photon emission computed tomography scans in an epileptic patient receiving long-term high-dose phenytoin therapy.

Quantitative assessment of regional cerebral blood flow (rCBF) was performed in a 22-year-old man with intractable temporal lobe epilepsy on long-term high-dose phenytoin (PHT) therapy, using single photon emission computed tomography (SPECT) with N-isopropyl-(iodine-123)-p-iodoamphetamine. In all the SPECT scans repeated three times with changes in the PHT dose, absolute rCBF values were lower in most of the cerebral and cerebellar regions measured, as compared with 5 normal subjects matched for sex and age, and 22 normal subjects including the 5 men. Both the cerebellar to frontal rCBF ratio and cerebellar to cerebral rCBF ratio in the patient persistently showed low values, probably reflecting abnormal relative cerebellar hypoperfusion, whereas X-ray computed tomography and magnetic resonance brain imaging showed no abnormal findings. However, this probable cerebellar abnormality on SPECT was to some degree reversible with decreases in the PHT dose. These results suggest the utility of SPECT scans for early detection of cerebellar abnormalities known to be often present in epileptic patients, and imply a risk of long-term high-dose PHT therapy.

Adult↗
PubMed1993

123I-IMP SPECT brain imaging in epileptic psychosis: a study of two cases of temporal lobe epilepsy with schizophrenia-like syndrome.

To examine the relationship between functional abnormality of the brain and the development of epileptic psychosis, regional cerebral blood flow (rCBF) patterns with single photon emission computed tomography (SPECT) using N-isopropyl-(iodine-123)-p-iodoamphetamine (123I-IMP) were serially examined in interictal stages with and without the psychotic state in 2 medicated patients with temporal lobe epilepsy with schizophrenia-like syndrome. Both patients had epileptic EEG foci in the left temporal lobe and schizophrenia-like syndrome in Bruens' classification of epileptic psychosis, mainly consisting of auditory hallucinations and delusions of persecution and reference accompanying the enhancement of interictal epileptic discharges. In both patients, the SPECT scans obtained in the stages without the psychotic state revealed focal hypoperfusion images in the left temporal lobe regionally consistent with the EEG foci. On the other hand, the SPECT scans in the stages with the psychotic states revealed focal hyperperfusion images in the left temporal lobe or amygdala in case 1, and a normal perfusion pattern without asymmetric images of the right and left temporal lobes in case 2. These results suggest that temporo-limbic dysfunction, in particular hyperfunction in the temporo-limbic system in the left dominant hemisphere, arises at the time of the psychotic state in epileptic psychosis.

Adult↗
PubMed1993

Three cases of alopecia areata induced by zotepine.

One schizophrenic and two manic-depressive patients who after the administration of zotepine, a new antipsychotic and antimanic drug, developed alopecia areata, a kind of autoimmune disease, are reported. They recovered following the discontinuation or decrease in the dose of zotepine. These three cases of alopecia areata suggest that the antipsychotic drugs may induce autoimmune disease through their neuropsychological effect.

Adult↗
PubMed1993

Efficacy of sulthiame (Ospolot) on motor partial seizure status during sleep in a patient with motor cortex epilepsy.

An 18-year-old female patient with a particular form of intractable motor cortex epilepsy, in which motor partial seizure status occurred only during sleep every night, was reported focusing on the drastic efficacy of sulthiame on the seizure status. Moreover, the present study demonstrated that single photon emission computed tomography (SPECT) and pulse oximetry examinations, both of which were performed in the ictal state, were useful for the regional diagnosis of the epileptic focus and observations of the seizure frequency, respectively. The therapeutic effect, epileptic picture and clinical examinations described here appear to be relatively rare in the literature, and therefore, this case report may be of clinical significance.

Adult↗
PubMed1993

Probable cerebellar abnormality on 123I-IMP SPECT scans in epileptic patients with long-term high-dose phenytoin therapy. Based on observation of multiple cases.

Quantitative assessment of regional cerebral blood flow (rCBF) in the bilateral cerebral and cerebellar cortices was performed in 13 epileptic patients receiving long-term high-dose phenytoin (PHT) therapy, using single photon emission computed tomography (SPECT) with N-isopropyl-(iodine 123) p-iodoamphetamine. In 4 of the 13 patients, both the cerebellar to frontal rCBF ratio and cerebellar to cerebral rCBF ratio showed low values as compared with those in 22 normal subjects matched for sex and age, probably reflecting abnormal relative cerebellar hypoperfusion. None of the 4 patients showed any abnormal findings on X-ray computed tomography or magnetic resonance brain imaging. The patients with a history of acute PHT intoxication tended to show the abnormal relative cerebellar hypoperfusion. These results suggest the utility of SPECT scans for early detection of cerebellar abnormalities known to be often present in epileptic patients, and imply a risk of long-term high-dose PHT therapy.

Adult↗
PubMed1993

Quantitative assessment of regional cerebral blood flow with 123I-IMP in normal adult subjects.

Quantitative assessment of regional cerebral blood flow (rCBF) in the bilateral cerebral and cerebellar cortices was performed in 22 normal adult subjects consisting of an early twenties group (5 men and 9 women, 20-22 years) and middle age group (3 men and 5 women, 41-52 years), using single photon emission computed tomography (SPECT) with N-isopropyl-(iodine 123) p-iodoamphetamine. Absolute rCBF values in each region in the 22 subjects ranged from 46 to 102 ml/100 g/min (mean 69.1, standard deviation 13.7 ml/100 g/min). The absolute rCBF values were significantly higher in women than in men, and in the early twenties group than in the middle age group. In addition, based on each absolute rCBF value, the interhemispheric asymmetry, anterior to posterior ratio and cerebellar to frontal ratio in rCBF were calculated. These results may be useful as indexes for detecting organic and functional brain abnormalities in various neuropsychiatric diseases.

Adult↗
PubMed1992

Facilitative effect of carbamazepine on previously induced hippocampal long-term potentiation.

The effects of carbamazepine (CBZ) on previously induced hippocampal long-term potentiation (LTP) were examined. Acute experiments were performed on 33 adult, male rabbits. Field potentials in the dentate gyrus were elicited by single shocks to the perforant path, and LTP was induced by tetanic stimulation to the pathway without induction of seizure discharge. At a CBZ serum level of about 5 micrograms/ml (value +/- SD = 5.40 +/- 1.28 micrograms/ml), the previously induced LTP in population spikes (PSs) and population excitatory postsynaptic potentials (EPSPs) was facilitated. At a CBZ serum level of about 15 micrograms/ml (value +/- SD = 14.28 +/- 1.29 micrograms/ml), the LTP in PS alone was decreased. The effects of carbamazepine on synaptic inhibition were examined by the paired-pulse test. The inhibition was enhanced with induction of LTP. After administration of CBZ, at a CBZ serum level of about 5 micrograms/ml the inhibition was further enhanced, while it was attenuated at a CBZ serum level of about 15 micrograms/ml. These results suggest that CBZ has a facilitative effect on previously induced LTP.

Animals↗
PubMed1992

Paradoxical enhancement of hypoperfusion single photon emission CT images in epileptic focus with bemegride activation. Observation from subtraction of 99mTc hexamethyl-propyleneamine oxime brain single photon emission CT images.

Changes of brain images in single photon emission CTs (SPECTs) before and after intravenous injection of bemegride were examined with simultaneous EEG recording in a patient with occipital lobe epilepsy and in a hysteric patient, using a new method, i.e. subtraction of the SPECT images with 99mTc hexamethyl-propyleneamine oxime. The bemegride injection in the epileptic patient paradoxically intensified the hypoperfusion images as epileptic foci in SPECTs, associated with enhanced interictal epileptic discharges, whereas the hysteric showed no such effects. These findings suggest that the hypoperfusion images closely correlate to the severity of epileptic activity, reflecting a functional rather than a morphological deficit.

Adult↗
PubMed1992

Acutely administered haloperidol-induced pattern changes of regional cerebral blood flow in schizophrenics. Observation from subtraction of brain imaging with single photon emission computed tomography using technetium-99m hexamethyl-propyleneamine oxime.

Changes in regional cerebral blood flow in brain images with single photon emission computed tomography using technetium-99m hexamethyl-propyleneamine oxime before and after intramuscular injection of haloperidol (0.08 mg/kg) were studied in 5 medicated subjects in their twenties, consisting of 5 schizophrenics and 1 patient with histrionic personality disorder, by a subtraction method of brain images. The haloperidol injection induced two types of perfusion pattern change; in 2 of the schizophrenics, a relative hypoperfusion in the frontal lobes in the images prior to injection was converted to a relative hyperperfusion. In the other 3 schizophrenics and in the patient with histrionic personality disorder, the slight left hemispheric dominance was changed to a marked right hemispheric dominance. The results indicate that haloperidol affects perfusion patterns in schizophrenics.

Acute Disease↗
PubMed1992

Widespread reduction of regional cerebral blood flow during hyperventilation-induced EEG slowing ('buildup'). Observation from subtraction of brain imaging with single photon emission computed tomography using technetium-99m hexamethyl-propyleneamine oxime.

To study the pathophysiological mechanisms of hyperventilation-induced EEG showing, i.e., the so-called 'buildup' phenomenon, changes in regional cerebral blood flow (rCBF) were investigated before and during the phenomenon in a 16-year-old woman with headache, thought to be of neurotic origin, by subtraction technique of brain images with single photon emission computed tomography using technetium-99m hexamethyl-propyleneamine oxime (99mTc-HMPAO). The tracer uptake during buildup decreased by 31-42% as compared to baseline values at rest before buildup in all of the measured regions, reflecting a widespread reduction in rCBF. Gas analyses of arterial blood collected during buildup showed a decrease in PaCO2, and increases in PaO2 and pH with a slight decrease in blood pressure and an increase in pulse rate. These results directly demonstrate a close correlation between the hyperventilation-induced EEG and rCBF changes, suggesting that the buildup phenomenon results from cerebral ischemic change, presumably due to cerebral vasoconstriction caused by the PaCO2 decrease.

Adolescent↗
PubMed1992

Metoclopramide-induced parkinsonism and depression.

A 46-year-old female patient with metoclopramide-induced parkinsonism and depression was reported in view of the rarity of the concurrent development of these side effects. A risk of metoclopramide administration is suggested.

Depression↗
PubMed1991

Visual dysfunction in treated schizophrenia suggested by visual evoked potentials from pattern-reversal stimulation.

Steady-state visual evoked potentials (steady-state VEPs) from pattern-reversal stimulations were compared in treated schizophrenic patients and normal subjects matched for sex and age. The VEP amplitudes were more variable in the patients than in the controls. Furthermore, the VEP amplitudes of the patients mostly showed little or no change when the check size was varied, in contrast to the controls who showed a marked check size effect. These results suggest that schizophrenics receiving drugs have dysfunction of the visual system, especially an inability to respond adequately to changes of visual information.

Adult↗