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Biomedical subjects

I Jibiki

Publications and source records attributed to I Jibiki.

At least 19 recordsLinked to original sources
PubMed2000

Effects of MK-801 on clozapine-induced potentiation of excitatory synaptic responses in the perforant path-dentate gyrus pathway in chronically prepared rabbits.

We previously found that the atypical antipsychotic drug, clozapine, when intraperitoneally (i.p.) injected, long-lastingly potentiated excitatory synaptic responses elicited in the dentate gyrus by single electrical stimulations to the perforant path in chronically prepared rabbits, and called this phenomenon 'clozapine-induced potentiation'. In the present study, we likewise examined whether clozapine-induced potentiation is caused by NMDA receptor-mediated neurotransmission in the perforant path-dentate gyrus pathway of chronically prepared rabbits. The non-competitive NMDA receptor antagonist - 5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclo-hepten-5,10-imino hydrogen maleate (MK-801; 1.0 mg/kg, i.p.) - completely prevented the potentiation of synaptic responses induced by subsequent administration of 20 mg/kg clozapine, whereas the 0.5 mg/kg dose had virtually no effect on the potentiation. These results suggest that the effect of clozapine requires NMDA receptor activation.

Analysis of Variance↗
PubMed2000

Diesel exhaust particles activate p38 MAP kinase to produce interleukin 8 and RANTES by human bronchial epithelial cells and N-acetylcysteine attenuates p38 MAP kinase activation.

Air pollutants including diesel exhaust particles (DEPs) have been shown to enhance allergic responses. DEPs stimulate airway epithelial cells to produce various cytokines; however, the intracellular signal transduction pathway and the involvement of reduction and oxidation (redox) control in DEP-activated signaling have not been determined. In the present study, we therefore examined the role of p38 mitogen-activated protein (MAP) kinase in DEP-induced interleukin 8 (IL-8) and RANTES production by human bronchial epithelial cells (BECs) in order to clarify the intracellular signal transduction pathway that regulates IL-8 and RANTES production. In addition, we also examined the effect of a thiol-reducing agent, N-acetylcysteine (NAC), on DEP-induced p38 MAP kinase activation and cytokine production in order to clarify the redox control mechanism in DEP-induced p38 MAP kinase activation and IL-8 and RANTES production. The results showed that DEP induced IL-8 and RANTES production and the threonine and tyrosine phosphorylation of p38 MAP kinase, reflecting the activation of p38 MAP kinase in BECs. SB 203580, as the specific inhibitor of p38 MAP kinase activity, inhibited DEP-induced IL-8 and RANTES production. NAC inhibited DEP-induced p38 MAP kinase activation and IL-8 and RANTES production. These results indicate that p38 MAP kinase plays an important role in the DEP-activated signaling pathway that regulates IL-8 and RANTES production by BECs and that the cellular redox state is critical for DEP-induced p38 MAP kinase activation leading to IL-8 and RANTES production.

Acetylcysteine↗
PubMed2000

Selective inhibitor of p38 mitogen-activated protein kinase inhibits lipopolysaccharide-induced interleukin-8 expression in human pulmonary vascular endothelial cells.

Adult respiratory distress syndrome (ARDS) characterized by permeability edema is observed in severe insults such as bacteremia sepsis. Interleukin (IL)-8, which chemoattracts and activates neutrophils, has been suggested to play an important role in the production of ARDS. Therefore, the inhibition of IL-8 production is an important strategy for the treatment of ARDS. Recent studies have revealed the role of p38 mitogen-activated protein (MAP) kinase in cytokine expression and the inhibition by a selective inhibitor of p38 MAP kinase activity of cytokine expression in a variety of cell types. However, little is known about the role of p38 MAP kinase in lipopolysaccharide (LPS)-induced IL-8 expression in pulmonary vascular endothelial cells and the effect of a selective p38 MAP kinase inhibitor on it. In the present study, we therefore attempted to clarify these issues. The results showed that LPS induced p38 MAP kinase phosphorylation and activity, and SB 203580 as a selective inhibitor of p38 MAP kinase activity inhibited p38 MAP kinase activity and IL-8 expression in LPS-stimulated pulmonary vascular endothelial cells. These results indicate that p38 MAP kinase regulates LPS-induced IL-8 expression in pulmonary vascular endothelial cells. Although it is currently not known whether SB 203580 is capable of producing beneficial effects on ARDS, a strategy of inhibiting p38 MAP kinase activity by a selective p38 MAP kinase inhibitor may apply to the therapy for ARDS.

Blotting, Northern↗
PubMed1999

p38 MAP kinase regulates RANTES production by TNF-alpha-stimulated human pulmonary vascular endothelial cells.

BACKGROUND: RANTES plays an important role in the production of allergic inflammation of the airway through its chemotactic activity for eosinophils. However, the intracellular signal regulating RANTES expression in human pulmonary vascular endothelial cells has not been determined. In the present study, therefore, we examined the role of p38 mitogen-activated protein (MAP) kinase in RANTES production by tumor necrosis factor (TNF)-alpha-stimulated pulmonary vascular endothelial cells in order to clarify the signal transduction pathway regulating RANTES production by pulmonary vascular endothelial cells. METHODS: We examined p38 MAP kinase activation, and the effect of SB 203580, as the specific inhibitor for p38 MAP kinase, on p38 MAP kinase activity and RANTES production by TNF-alpha-stimulated human pulmonary vascular endothelial cells. RESULTS: The results showed that TNF-alpha induced RANTES production and p38 MAP kinase activity in human pulmonary vascular endothelial cells. Abrogation of p38 MAP kinase activity by SB 203580 repressed TNF-alpha-induced p38 MAP kinase activity and RANTES production. CONCLUSIONS: These results indicate that p38 MAP kinase plays an important role in the TNF-alpha-activated signaling pathway which regulates RANTES production by human pulmonary vascular endothelial cells.

Cells, Cultured↗
PubMed1998

An autopsied case of Creutzfeldt-Jakob disease with the lateral geniculate body lesion showing antagonizing correlation between periodic synchronous discharges and photically induced giant evoked responses.

We reported an necropsy finding of a patient with Creutzfeldt-Jakob disease (CJD) who showed photo-stimulated giant spikes that simultaneously suppressed periodic synchronous discharges (PSD) and the loss of pupillary light reflex during the course of the illness. The necropsy revealed extensive gray and white matter lesions, and both the lateral geniculate body (LGB) and pregeniculate body were primarily affected. The superior colliculus, optic nerve and tracts were not affected. The cerebral cortices particularly of the occipital lobe were severely damaged. The Gennari line, however, was spared from lesion. The primary involvement of the LGB has been reported infrequently in CJD, however, it appears to be associated with the unusual electroencephalograph (EEG) feature of the present case. The pregeniculate lesion contributed to the loss of pupillary reflex. This finding indicates that the visual pathway may be involved in the mechanism of the generation of PSD in CJD.

Action Potentials↗
PubMed1996

Clozapine-induced potentiation of synaptic responses in the perforant path-dentate gyrus pathway in chronically prepared rabbits.

To examine the contribution of N-methyl-D-aspartate (NMDA) receptors in the mechanisms underlying the action of antipsychotics, we investigated the effects of a representative atypical antipsychotic, clozapine (CLZ), on the induction of long-term potentiation (LTP) in the perforant path-dentate gyrus pathway in 15 chronically prepared rabbits. Eventually, neither low (10 mg/kg) nor high (20 mg/kg) doses of CLZ intraperitoneally injected had any effects on LTP induction. However, the high dose CLZ always potentiated the ordinary synaptic responses induced by single stimulations before the LTP induction. The present study indicates a new finding, the presence of "CLZ-induced potentiation', although it needs further investigation whether NMDA receptors contribute to this potentiation.

Animals↗
PubMed1995

Antagonizing correlation between periodic synchronous discharges and photically induced giant evoked responses in Creutzfeldt--Jakob disease (Heidenhain type): a case study.

In a patient with Creutzfeldt-Jakob disease (Heidenhain type), which was characterized by the initial onset of visual symptoms and proved by autopsy, there was an antagonizing correlation between spontaneously-induced periodic synchronous discharges and photically induced giant evoked responses. In addition, the two electroencephalogram features appeared and disappeared in parallel with each other during the clinical course of the illness.

Aged↗
PubMed1995

Single photon emission computed tomography studies of partial epilepsies.

At present, in the field of clinical epilepsy, it has been established that single proton emission computed tomography (SPECT) is useful for the regional determination of epileptic foci. In particular, it seems to be of great advantage to the field of clinical epilepsy that epileptic foci situation in the deep regions of the brain are detectable by the three-dimensional resolution power in SPECT, because such foci are not often represented on routine scalp electroencephalograph (EEG). In reference to our review published previously, recent findings in SPECT studies of partial epilepsies are surveyed here.

Anticonvulsants↗
PubMed1994

Comparison of benzodiazepine receptor and regional cerebral blood flow imaging of epileptiform foci in hippocampal kindled rabbits: a study with in vivo double tracer autoradiography using 125I-iomazenil and 99mTc-HMPAO.

To clarify experimentally whether benzodiazepine (Bz) receptor or regional cerebral blood flow (rCBF) imaging is more sensitive in the detection of epileptic foci, we simultaneously examined the Bz receptor and rCBF distribution changes in hippocampal kindled rabbits with in vivo double tracer autoradiography using 125I-labeled Ro 16-0154 (125I-Iomazenil) and 99mTc-labeled hexamethylpropylene amine oxime (99mTc-HMPAO). In visual and quantitative analyses, 125I-Iomazenil accumulation in brain slices extracted after the completion of the kindling was markedly and extensively decreased in the kindled right CA1 region, and further in the right temporal lobe, dentate gyrus, CA2, CA4, and bilateral CA3 regions, regarded as the propagated sites of seizure discharges. 99mTc-HMPAO accumulation was much more slightly and less extensively decreased in the right CA1, frontal, temporal and dentate gyri. Further, this decrease in 125I-Iomazenil accumulation was not due to neuropathological abnormalities, which consisted only of tissue damage corresponding to electrode track in the CA1. Both the kindled and propagated sites are known to have a possibility of acquiring epileptogenesis as experimental epileptic foci. These results suggest that Bz receptor imaging is much more sensitive in the detection of epileptic foci than rCBF imaging, and therefore that Bz receptor imaging is useful in clinical epilepsy.

Animals↗
PubMed1994

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

We investigated the effects of a representative anti-epileptic or anti-psychotic drug, carbamazepine (CBZ), on the induction of long-term potentiation (LTP) in the perforant path-dentate gyrus pathway in 15 chronically prepared rabbits. Pharmacokinetically injected low-dose CBZ, which produced steady serum levels of 2.2-3.3 micrograms/ml (mean +/- S.D. 2.85 +/- 0.40), variably affected the induction of LTP, blocking it or showing almost no effect. The high-dose CBZ, which produced steady serum levels of 6.5-8.6 micrograms/ml (8.01 +/- 0.87), always blocked the induction of LTP. These results indicate that CBZ dose-dependently blocks the induction of LTP. The possible mechanisms underlying this blockade are discussed, especially in association with the possible inhibitory action of CBZ on N-methyl-D-aspartate (NMDA) receptors.

Animals↗
PubMed1994

Comparison of benzodiazepine receptor and regional cerebral blood flow imaging of epileptiform foci in hippocampal kindled rabbits: a preliminary report.

To clarify experimentally which of benzodiazepine (BZ) receptor or regional cerebral blood flow (rCBF) imaging is more sensitive in the detection of epileptic foci, we simultaneously examined the BZ receptor and rCBF distribution changes in hippocampal kindled rabbits with in vivo double tracer autoradiography using 125I-labeled Ro 16-0154 (125I-Iomazenil) and 99mTc-labeled hexamethyl-propyleneamine oxime (99mTc-HMPAO). In visual analysis of brain slices extracted after the intravenous injection of the double tracer following the kindling completion, 125I-Iomazenil accumulation was more markedly and extensively decreased in the kindled right CA1 region mimicking a primary epileptic focus than 99mTc-HMPAO accumulation. Further, this decrease in 125I-Iomazenil accumulation was not due to neuropathological abnormalities which consisted only of tissue damage corresponding to electrode track in the right CA1. These results suggest that BZ receptor imaging is more sensitive in the detection of epileptic foci than rCBF imaging and, therefore, that BZ receptor imaging is useful in clinical epilepsy.

Animals↗
PubMed1994

Epilepsy and SPECT.

SPECT studies for rCBF imaging in clinical epilepsy are reviewed divided into interictal, ictal and postictal SPECT studies in partial and generalized epilepsies, as compared with the corresponding PET studies, and at times referring to SPECT studies in experimental models of epilepsy. All of the interictal, ictal and postictal SPECT scans in partial epilepsy are useful for the regional determination of epileptic foci, in view of the high appearance rates of focal abnormalities on these SPECT scans and good correlation with epileptic EEG foci. Mechanisms underlying the focal abnormality on interictal SPECT scans (i.e., focal hypoperfusion) image are complicative, and therefore, studies concerning the underlying mechanisms are reviewed with regard to correlations of the SPECT abnormality with the following various clinical factors: focal organic lesions on X-ray CT or MRI scans, frequencies of clinical seizures or interictal seizure discharges on EEGs, background EEG activity, propagation of epileptic activity, antiepileptic drugs, and cognitive functions. Further, new neurochemical SPECT studies using 123I-Iomazenil for benzodiazepine receptor imaging in clinical epilepsy are reviewed and compared with earlier SPECT studies for rCBF imaging with regard to their utility in regional determination of epileptic foci. In addition, the few SPECT or PET studies available on epileptic psychosis are reviewed.

Animals↗
PubMed1994

Alopecia areata associated with haloperidol.

A patient with a 7-year history of depression relapsed after self-discontinuation of antidepressant drugs. He was admitted to our hospital and re-administered amoxapine 150 mg. p.o. per day, and further given haloperidol 5 mg i.m. or p.o. per day because he was suicidal and excited. One month later, an area of alopecia was found on the back of his head. Immediately, he received dermatological treatment. The psychotropic drugs were continued, but the hair loss was unchanged after one month. So, haloperidol alone was discontinued. One week later, the hair loss had stopped and a month later alopecia had virtually disappeared. We suggest that alopecia areata is associated with haloperidol.

Administration, Oral↗
PubMed1994

Utility of 123I-IMP SPECT brain scans for the early detection of site-specific abnormalities in Creutzfeldt-Jakob disease (Heidenhain type): a case study.

Serial changes in brain imaging of regional cerebral blood flow with single photon emission computed tomography (SPECT) using N-isopropyl-(iodine-123) p-iodoamphetamine (123I-IMP) were observed in a patient with probable Heidenhain type of Creutzfeldt-Jakob disease, which was characterized by the initial onset of visual symptoms. Corresponding to the visual signs and periodic synchronous discharges localized in the bilateral parietal and occipital regions on EEG, focal hypoperfusion images in the occipital lobes were detected on the SPECT scan before brain X-ray computed tomography and magnetic resonance imaging showed any abnormalities. These results suggest that SPECT brain imaging is useful in the early detection of site-specific abnormalities in Creutzfeldt-Jakob disease.

Aged↗
PubMed1994

Case study of monosymptomatic delusion of unpleasant body odor with structural frontal abnormality.

We report a 63-year-old man with a monosymptomatic delusion of unpleasant body odor contracted at the age of 61 years, who believed that his body reeked of some type of paint. He had symmetrical atrophy in the bilateral frontal lobes of unknown etiology on MRI. Further, quantitative rCBF measurement with SPECT brain scan using 99mTc-HMPAO showed relative hypoperfusion localized in the bilateral frontal lobes. EEG, neurological and neuropsychological tests were all normal, including the WAIS-R and Wechsler Memory Scale tests. However, he showed poor results on the Wisconsin Card Sorting test, presumably on account of frontal dysfunction, attaining only two categories with frequent perseverative errors. Although it is undetermined whether the illness in this case can be classified as organic delusional syndrome or paranoid disorder according to DSM-III-R criteria, these results imply that delusions are associated with frontal lobe abnormality.

Atrophy↗
PubMed1994

Correlations between quantitative EEG and regional cerebral blood flow (SPECT) in patients with partial epilepsy.

During interictal periods in 9 patients with partial epilepsy we examined whether there were correlations between the relative power of background EEG (power spectral analysis) and the absolute values of regional cerebral blood flow (rCBF) measured by 99mTc hexamethylpropylene amine oxime (HMPAO) SPECT in each cerebral region. None of the patients had any organic cerebral lesions on X-ray CT examinations, neurological abnormalities or mental retardation. There was an inverse correlation between rCBF and the relative power of the theta band, and a direct correlation between rCBF and that of the alpha band of 10-12.8 Hz, in the right and/or left frontal, parietal and temporal regions. In the occipital regions, there was a direct correlation only between rCBF and the relative power of the beta band. These correlations were noted whether the analyzed regions were epileptic foci or not. These results suggest that background EEG and rCBF changes in epileptic patients are closely coupled.

Adult↗
PubMed1993

The Gogi (word-meaning) syndrome with impaired kanji processing: alexia with agraphia.

Two cases, one with probable Pick's disease and one with herpes simplex encephalitis, are presented, focusing on Gogi (word-meaning) aphasia-like syndrome as their salient clinical feature. Their aphasic symptoms were characterized by impaired kanji processing and preserved kana processing in writing and oral reading known as a defining feature of Gogi aphasia, but little evidence of so-called "phonetic use of kanji in writing" and "confusion between on- and kun-readings of kanji in oral reading" often observed in Gogi aphasia. Systematic neuropsychological test batteries administered to them showed that the selective impairment of kanji processing did not always arise from a disturbance of a specific ability known to be essential to Gogi aphasia (i.e., failure in comprehending the semantic content of spoken and written language), but rather from an amnestic disruption in the ability to access the correct orthographic and phonological forms of kanji words. This selective impairment of kanji processing may be compatible with "alexia with agraphia of kanji," recently known to be attributable to left posterotemporal lesions. These results suggest that Gogi aphasia (or similar syndromes) is not necessarily a real syndrome but a polytypic constellation of symptoms.

Adult↗