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Biomedical subjects

I Jibiki

Publications and source records attributed to I Jibiki.

At least 55 records · Page 3Linked to original sources
PubMed1991

Inhibitory effect of MK-801 (noncompetitive NMDA receptor antagonist) on kindling-induced synaptic potentiation in acutely prepared rabbits.

We investigated effects of a noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist, MK-801, on potentiation of field potentials elicited in the dentate gyrus by single shocks to the perforant path after kindling to the pathway in acutely prepared rabbits. MK-801, which was intracortically injected after the establishment of kindling-induced potentiation, remarkably and dose-dependently reduced the potentiation. These results suggest that activated NMDA receptors contribute substantially to the expression of kindling-induced potentiation.

Animals↗
PubMed1991

Tc-99m HMPAO SPECT analysis of neuroleptic effects on regional brain function.

This report describes a new approach to the evaluation of neuroleptic effects on regional brain function. Using Tc-99m HMPAO SPECT imaging, consecutive brain perfusion studies before and after acute haloperidol administration were performed on three schizophrenic patients and two normal volunteers. The antipsychotic drug ameliorated the hypoactivity in the frontal lobe and suppressed the hyperactivity in the temporo-occipito-parietal lobe selectively in the dominant hemisphere in the schizophrenic patients. It did not exert a significant influence on the brain perfusion pattern in normal volunteers. This nuclear medicine technique seems to be useful for the evaluation of drug effects in psychiatric diseases.

Adult↗
PubMed1991

Comparison of kindling at short interstimulus intervals in acutely and chronically prepared rabbits.

For the purpose of contributing methodologically to experimental research on epilepsy, we investigated whether a difference exists in kindling development between acute and chronic preparations using identical species of animals, kindled brain tissues, stimulus intervals, and intensities. Seizure-threshold stimulations repeatedly applied at 5-min intervals to the unilateral visual cortex in rabbits completed the generalization of epileptiform discharge trains after the 11th-24th trials in the acute preparations concomitantly with an increase in the afterdischarge duration and the development of independent discharges, whereas they induced no kindling phenomena even with 50 trials in the chronic preparations. These results indicate that there is an extreme difference in kindling susceptibility between acute and chronic preparations, resulting, presumably, from multifactorial dissimilarities in these experimental conditions.

Animals↗
PubMed1991

Kindling-induced neuronal plasticity in the dorsal hippocampus CA1 in acutely prepared rabbits: unit activity analysis.

To elucidate kindling-induced neuronal plasticity single cell discharge analysis, responses consisting of action potentials orthodromically elicited in the dorsal hippocampus CA1 by a single electric shock to the neighboring region were serially observed before, during and after kindling i.e. the repetition of stimulus trains applied to the same hippocampal region in acutely prepared rabbits. Eventually, the orthodromic unit response with identical amplitudes, which were regarded as a single cell origin, gradually increased in the firing rate at the interictal stages during and after the kindling. Further, an inhibitory period following the unit responses, during which no spontaneous unit activity appeared, was remarkably prolonged during and after the kindling. Both the increase of the unit responses and the prolongation of the inhibitory period irreversibly lasted for hours once they occurred. Such unit activity analysis confirms kindling-induced excitatory and inhibitory synaptic plasticity.

Action Potentials↗
PubMed1991

123I-IMP brain SPECT imaging in a patient with the interval form of CO poisoning.

N-isopropyl-[123I]-p-iodoamphetamine (123I-IMP) single-photon emission computed tomography (SPECT) brain imaging was repeatedly performed in a 68-year-old man with the interval form of CO poisoning. The initial SPECT under an akinetic-mutism state following the interval period of about 18 days showed high-grade hypoperfusion images in diffuse regions extending to both the gray and white matter in the cerebral cortex. The second SPECT examination performed 328 days after the acute poisoning showed that the diffuse hypoperfusion images had become lighter but remained to a degree consistent with the delay in the recovery from the akinetic-mutism state. The high utility of SPECT brain imaging in determining the diagnosis or prognosis of CO poisoning was discussed in comparison with X-ray or magnetic-resonance imaging findings.

Aged↗
PubMed1991

Regional relationships between focal hypofixation images in 123I-IMP single photon emission computed tomography and epileptic EEG foci in interictal periods in patients with partial epilepsy.

Single photon emission computed tomographic (SPECT) brain scans with N-isopropyl-(iodine-123)-p-iodoamphetamine were performed in interictal periods in 40 patients with partial epilepsies and normal X-ray CT findings, and the regional relationships between the SPECT abnormalities and interictal epileptic EEG foci were studied. Twenty-six patients (65%) had abnormal SPECT images consisting of one or more focal hypofixation images, i.e., zones of decreased regional cerebral blood flow, while the remaining 14 patients showed normal images. Nineteen (73%) of the 26 patients showed complete or partial regional agreement between the abnormal SPECT findings and the interictal epileptic EEG foci determined from EEGs recorded repeatedly during their clinical course, while the regional relationships with the EEG foci determined from the single EEG recorded just after the SPECT scans or a short interval after the scans showed a lower rate of agreement (13 of 21 patients, 61.9%). These results confirm the utility of SPECT scans in the regional diagnosis of epileptic foci.

Adolescent↗
PubMed1991

Effect of therapy with oxygen under high pressure on regional cerebral blood flow in the interval form of carbon monoxide poisoning: observation from subtraction of technetium-99m HMPAO SPECT brain imaging.

Changes in brain images with single photon emission computed tomography (SPECT) using 99mTc hexamethylpropyleneamine oxime (HMPAO) before and after therapy with oxygen under high pressure (OHP) were measured in a 66-year-old man with the interval form of carbon monoxide (CO) poisoning by a new technique, i.e., subtraction of brain images. This study was performed 187 days after acute CO poisoning, in a state of chronic akinetic mutism that followed a lucid interval. A diffuse, but frontal-dominant, hypoperfusion pattern involving both the gray and white matter was observed in the pre-OHP SPECT image. After OHP, regional cerebral blood flow increased in both the gray and white matter and markedly increased in the frontal cortical regions. The present finding suggests that OHP is effective against the chronic state of the interval form of CO poisoning.

Aged↗
PubMed1991

[EEG data filing system with personal computer and magneto-optical disc].

We established a new computerized EEG filing system, in which an EEG machine was connected to an EEG filing unit which consisted of a personal computer with a 32 bit CPU, 18 channel analog -to-digital and digital-to-analog converters, and a magneto-optical disc driver. This system has the following merits. The system was space-saving, the space required to store the EEG data, being only 1/500 of that required for storing EEG record. Though the system had two independent EEG filing units, our original file configuration enabled us to have access to all of the recorded EEG data anytime for more than 10 years. The system enabled us to display EEG data continuously on the high resolution CRT, just as if turning the page of an EEG record paper, and through the quick scanning, enabled us to view the entire EEG pattern. Furthermore, the system enabled us to conduct reliable digital analysis for EEG data by entering the EEG data without artifacts into a data processor after confirmation on the display. In the system, we used data files with the MS-DOS operating system. This enabled us to analyze the data obtained by a personal computer operating on other systems, by transferring the data to a floppy disc operating on our system. Our EEG filing system allows quick access to data as well as mass data storage.

Electroencephalography↗
PubMed1990

MK-801 (non-competitive NMDA receptor antagonist)-induced blockade of the 'burst response' in the dentate gyrus after perforant path kindling in acutely prepared rabbits.

Effects of MK-801, a non-competitive antagonist of N-methyl-D-aspartate (NMDA) receptors, were observed on the 'burst responses' elicited in the dentate gyrus by single shocks to the perforant path after kindling to the pathway in acutely prepared rabbits. The intracortical injection of 10 microM of an MK-801-containing solution almost completely blocked the previously induced burst responses, suggesting that activation of the NMDA receptor or the receptor-linked ion channel greatly contributes to the manifestation of the burst responses.

Animals↗
PubMed1990

Fluctuations of interictal brain imaging in repeated 123I-IMP SPECT scans in an epileptic patient.

Single photon emission computed tomography (SPECT) brain scans with N-isopropyl-(iodine 123) p-iodoamphetamine (123I-IMP) were performed three times in interictal periods in a 35-year-old man with intractable frontal lobe epilepsy and normal X-ray CT findings. The first scan showed decreased 123I-IMP uptake in the right frontal lobe. This abnormal image was regarded as the primary focus of his epilepsy on the basis of its regional agreement with focal epileptic discharges on EEGs. In the second scan, he showed normal imaging, while the third scan showed the same abnormal image as before, in the right frontal lobe. The frequency of his clinical seizures was almost unchanged during the intervals between scans and further EEGs recorded soon after each scan showed almost no changes in the basic activities and frequency of the epileptic discharges. Such fluctuations in SPECT brain imaging suggest that the severity of functional inactivation underlying the focal hypoperfusion image as an epileptic focus may fluctuate considerably in the interictal state with no relation to the clinical features of epilepsy.

Adult↗
PubMed1990

High reproducibility of regional abnormalities on interictal 123I-IMP SPECT brain scans in adults with partial epilepsy.

The reproducibility of two N-isopropyl-(iodine 123) p-iodoamphetamine (123I-IMP single photon emission computed tomography (SPECT) scans both taken during interictal periods was studied in 13 adult patients with partial epilepsy who had normal CT scans. The frequency of the seizures and the nature of the ictal symptoms were virtually unchanged during the interval between the two SPECT scans performed in each case. In 8 (72.7%) of 11 patients who had abnormal images consisting of focal hypofixation images of 123I-IMP, i.e. zones of decreased regional cerebral blood flow on the first scans, complete or partial regional reproduction of the SPECT abnormalities was observed. This high reproducibility supports the usefulness of SPECT scans in the regional diagnosis of epileptic foci.

Amphetamines↗
PubMed1990

Comparative experimental study of antiepileptics--regional specificity of antiepileptic action of carbamazepine, phenobarbital and valproate sodium.

The antiepileptic action of carbamazepine (CBZ), phenobarbital (PB), and valproate sodium (VPA) was examined in 109 adult male rabbits during steady state serum levels produced on the basis of the pharmacokinetics of each drug. The duration and discharge pattern of electrically induced focal and secondarily generalized after-discharges (ADs) in the motor, visual cortices and hippocampus were compared before and after administration of doses of each drug. A CBZ level of 3-30 micrograms/ml shortened the duration of both neocortical and hippocampal ADs. CBZ at levels above 5 micrograms/ml suppressed the spread in the secondarily generalized ADs originating from the neocortical areas, but not that originating from the hippocampus. PB levels of 10-80 micrograms/ml shortened the duration of both neocortical ADs, especially motor ADs, whereas they had little or no effect on the hippocampal ADs. VPA showed inhibitory effects on both the neocortical and hippocampal AD durations only at high levels of 400-1,100 micrograms/ml. However, the inhibitory effects were more marked on the latter than the former, and further, the effects were enhanced as time elapsed. These results suggest that the action of each drug on focal seizures is region-specific.

Animals↗
PubMed1990

Imaging of propagated sites of epileptic discharges in repeated 123I-IMP SPECT scans.

Single-photon emission computed tomographic (SPECT) brain scans with N-isopropyl-(iodine-123-p-iodoamphetamine (123I-IMP) were performed twice at an interval of about 2.5 years in the interictal period in an adult patient with occipital-lobe epilepsy. The first SPECT scan showed an abnormal image of decreased 123I-IMP uptake in the right occipital lobe. This abnormal image was regarded as the primary focus of his epilepsy on the basis of its regional agreement with right-occipital spikes consistently seen in interictal electroencephalographic recordings throughout his clinical history. In the second scan, he showed multiple abnormal images of decreased uptake in the right frontotemporal lobes and left occipital lobe together with the right occipital lobe. These additional abnormal images were considered to be propagated sites of epileptic discharges.

Adult↗
PubMed1989

Reexamination of 123I-IMP-SPECT at interictal stages in adult partial epilepsy.

123I-IMP-SPECT scans at the interictal stages in 13 epileptic patients with normal X-ray CT findings were reexamined at intervals of 1.9 +/- 0.8 years. Interictal scalp EEGs were recorded a few hours after each SPECT scan. All of the SPECT abnormalities indicated focal hypofixation images of 123I-IMP, i.e. zones of a decreased rCBF reflecting a functional inactivation. Among 11 patients with the SPECT abnormalities in the first SPECTs, eight cases had the complete or partial regional reproduction of the abnormalities in the second SPECTs. As changes in the SPECT findings, an alteration from the abnormal SPECT images to normal images (normalization), the reverse change, the enlargement and reduction of hypofixation sites were seen. Also the EEG foci had various changes (right and left regional changes, etc.). Because of these SPECT and EEG changes, the regional relationship between the SPECT abnormalities and EEG foci altered in 7 patients (a change from disagreement to agreement, etc.). The high reproduction rate of SPECT abnormalities appears to increase the reliability or utility of SPECT scans for a regional diagnosis of epileptic foci. The present SPECT changes, especially the normalization or the severse change, suggest that the interictal epileptic focus may have a functional fluctuation. In addition, the causes of regional disagreement between the SPECT abnormalities and EEG foci were discussed on the basis of the present SPECT and EEG changes.

Adult↗