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Biomedical subjects

H Ohishi

Publications and source records attributed to H Ohishi.

At least 127 records · Page 7Linked to original sources
PubMed1994

Spatiotemporally differential inhibition of pyramidal cells in the cat motor cortex.

1. The spatiotemporal pattern of inhibition in the cat motor cortex was studied in in vitro slice preparations in the presence of 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and 2-amino-5-phosphonovaleric acid (APV). 2. After intracortical microstimulation (0.5-6 microA), fast and slow inhibitory postsynaptic potentials (IPSPs) were produced in layers II-VI pyramidal cells and selectively reduced with bicuculline methiodide and phaclofen, respectively. 3. Fast IPSPs were maximally produced by stimulation of the same layer where their cell bodies were located, and they decreased in amplitude as the more superficial layer was stimulated. In contrast, slow IPSPs were maximally produced by stimulation of layer II regardless of the location of the recorded pyramidal cell and decreased in amplitude as the deeper layer was stimulated. 4. The reduction of amplitude of fast IPSPs, in response to a vertical shift of the stimulation site toward more superficial layers, was always correlated with an increase in rise time and with a shift of the reversal potential to a more hyperpolarized level. 5. When the stimulation site was moved horizontally to the more lateral site, fast IPSPs increased in latency and decreased in amplitude gradually without appreciable changes in rise time. Fast IPSPs could be evoked from horizontally remote sites of up to 800-1,200 microns. 6. Inhibitory interneurons, which are responsible for evoking fast IPSPs, appear to be distributed through almost all layers to send horizontally spreading parallel axons making synaptic contacts at different electrotonic distances along apical dendrites of single pyramidal cells. 7. Horizontal spreads were much less in slow IPSPs (< 340-680 microns). The time-to-peak of slow IPSPs produced in layer V pyramidal cells (159.5 +/- 6.8 ms, mean +/- SD, n = 10) was significantly (P < 0.0001) longer than that in layers II and III pyramidal cells (128.5 +/- 7.5 ms, n = 7). Asymmetric reversal properties of slow IPSPs were seen, suggesting the spatial dispersion of synaptic inputs along apical dendrites of pyramidal cells. 8. In layer V pyramidal cells, the time-to-peak of slow IPSPs decreased with increasing membrane hyperpolarization, indicating that the later portion of slow IPSPs was more sensitive to the membrane-potential change than the early portion. This further indicates that the late portion of slow IPSPs is generated at synapses on the more proximal dendrite of pyramidal cells than the early portion, contrary to that expected from the Rall's model of passive dendrite under the condition of synchronous inputs.(ABSTRACT TRUNCATED AT 400 WORDS)

2-Amino-5-phosphonovalerate↗
PubMed1993

Role of a metabotropic glutamate receptor in synaptic modulation in the accessory olfactory bulb.

Various functions of glutamate transmission are mediated by both ionotropic and metabotropic glutamate receptors. The metabotropic glutamate receptors (mGluRs) consists of at least six different subtypes that are classified into three subgroups, mGluR1/mGluR5, mGluR2/mGluR3, and mGluR4/mGluR6 (refs 1-5), but their physiological roles are largely unknown. Here we report the identification of a very potent agonist for mGluR2/mGluR3, DCG-IV, and the specific localization of mGluR2 in granule cell dendrites that form dendrodendritic synapses with mitral cells in the accessory olfactory bulb. Using the DCG-IV agonist for mGluR2 in combination with slice patch-recording, we demonstrate that the granule cell mGluR2 presynaptically suppresses inhibitory GABA (gamma-aminobutyrate) transmission to the mitral cell. Our results indicate that mGluR2 in granule cells plays an important role in the persistent excitation of olfactory sensory transmission in the accessory olfactory bulb by relieving mitral cells from the GABA inhibition.

Animals↗
PubMed1993

Immunohistochemical localization of a metabotropic glutamate receptor, mGluR5, in the rat brain.

A trpE-fusion protein containing a C-terminal sequence of a rat metabotropic glutamate receptor, mGluR5, was used to produce an antibody. On immunoblot, the antibody specifically reacted with mGluR5 expressed in mammalian cells and rat brain. Immunohistochemical analysis revealed intense mGluR5-like immunoreactivity (LI) in the olfactory bulb, anterior olfactory nuclei, olfactory tubercle, cerebral cortex, hippocampus, lateral septum, striatum, nucleus accumbens, inferior colliculus, and spinal trigeminal nuclei. The distribution pattern of mGluR5-LI corresponds very well with that of mGluR5 mRNA. Electron microscope analysis of the striatum revealed dense accumulation of immunoreaction products in dendrites which were often provided with asymmetrical synapses. These results suggest that mGluR5 is predominantly located in postsynaptic elements.

Animals↗
PubMed1993

Dominant expression of mRNA for prostaglandin D synthase in leptomeninges, choroid plexus, and oligodendrocytes of the adult rat brain.

Glutathione-independent prostaglandin D synthase [prostaglandin-H2 D-isomerase; (5Z,13E)-(15S)-9 alpha,11 alpha-epidioxy-15-hydroxyprosta-5,13-dienoate D-isomerase, EC 5.3.99.2] is an enzyme responsible for biosynthesis of prostaglandin D2 in the central nervous system. In situ hybridization with antisense RNA for the enzyme indicated that mRNA for the enzyme was predominantly expressed in the leptomeninges, choroid plexus, and oligodendrocytes of the adult rat brain. The findings agree with those obtained by immunohistochemical staining with antibodies against the enzyme. It was further revealed that prostaglandin D synthase activity was considerably greater in the isolated leptomeninges (14.2 nmol per min per mg of protein) and choroid plexus (7.0 nmol per min per mg of protein) than the activity in the whole brain (2.0 nmol per min per mg of protein). These results, taken together, indicate that the enzyme is mainly synthesized and located in the leptomeninges, choroid plexus, and oligodendrocytes in the brain.

Animals↗
PubMed1993

Distribution of the mRNA for a metabotropic glutamate receptor (mGluR3) in the rat brain: an in situ hybridization study.

Distribution of the mRNA for a metabotropic glutamate receptor, mGluR3, which is coupled to the inhibitory cAMP cascade, was examined in the central nervous system of the adult albino rat by in situ hybridization. The hybridization signals of mGluR3 were detected not only on neuronal cells but also on many glial cells throughout the brain and spinal cord. In the neuronal cells, prominent expression of mGluR3 mRNA was seen in the thalamic reticular nucleus. Moderately labeled neurons were seen in the anterior olfactory nucleus, cerebral neo- and mesocortical regions, lateral amygdaloid nucleus, ventral part of the basolateral amygdaloid nucleus, dorsal endopiriform nucleus, supraoptic nucleus, superficial layers of the superior colliculus, inferior colliculus, interpeduncular nucleus, superior olivary nuclei, and Golgi cells in the cerebellar cortex. Weakly labeled neurons were observed in the striatum, nucleus accumbens, ventral pallidum, globus pallidus, entopeduncular nucleus, lateral hypothalamic area, hypothalamic paraventricular nucleus, medial habenular nucleus, anterior pretectal nucleus, Barrington's nucleus, Nucleus O, paragenual nucleus, trigeminal sensory complex, cochlear nuclei, dorsal motor nucleus of the trigeminal nerve, dorsal cap of the inferior olive, spinal dorsal horn, and lamina X of the spinal cord. The stellate cells in the cerebellar cortex, and neurons in the deep cerebellar nuclei were also labeled weakly. The granule cell layer of the dentate gyrus, as a whole, appeared to be labeled intensely, but each of the granule cells was labeled only weakly. No significant labeling was detected in the mitral and tufted cells in the olfactory bulb, hippocampal pyramidal cells, Purkinje and granule cells in the cerebellar cortex, or somatic motoneurons. The distribution of mGluR3 mRNA in particular neurons and glial cells indicates specific roles of mGluR3 in the glutamatergic system of the central nervous system.

Animals↗
PubMed1993

[Percutaneous hot water injection therapy (PHoT) for hepatic tumors: a clinical study].

Percutaneous ethanol injection therapy (PEIT) has become widely used in the treatment of HCC. However, the indications for this method are limited by the toxicity of ethanol itself. Against this background, the authors turned their attention to the heat coagulation necrosis effect induced by boiled physiological saline (hot water) and devised percutaneous hot water injection therapy (PHoT) as a new local treatment method. PHoT was performed a total of 41 times in 13 patients (16 nodules) with HCCs measuring < or = 3 cm. Changes in AFP values, CT findings, angiographic findings before and after treatment, and histopathological findings of needle biopsy or resected specimen were investigated. AFP values decreased in all of the seven patients who initially showed high values. On CT, all lesions receiving PHoT became hypodense, with this change thought to indicate necrosis. Disappearance of the tumor stain was confirmed in the four patients in whom follow-up angiography was performed. In the six patients in whom needle biopsy was performed, disappearance and scaring of tumor cells were observed, while in the one patient in whom the tumor was resected, complete necrosis of the tumor was confirmed. PHoT, despite a small number of punctures, shows good anti-tumor effects, and has promise not only as a curative local treatment method for small HCCs but also in combination with TAE for large HCCs.

Aged↗
PubMed1993

[CO2US via an implantable port--drug distribution in intraarterial chemotherapy for hepatic tumors and evaluation of effect].

The distribution of blood flow was determined from the distribution of CO2 by US performed during the infusion of CO2 microbubbles via an implantable port (IP-CO2US) in intraarterial chemotherapy for hepatic tumor, and the usefulness of this method in determining tumor vascularity and evaluating the effects of therapy was investigated. A total of 16 patients, 12 of whom had metastatic liver tumor, two hepatocellular carcinoma, one gall bladder carcinoma, and one cholangiocellular carcinoma were studied. The enhanced areas in the liver in 16 patients in whom IP-CO2US was performed a total of 24 times were consistent in all cases with the enhanced areas demonstrated by IP-RI angiography performed a total of 10 times within 10 days, and were also consistent with one exception with the enhanced areas demonstrated by IP-CTA performed 14 times. The tumor detection rate was markedly higher with IP-CO2US than with plain US or IP-DSA, and was similar to that of IP-CTA. Evaluation of the vascularity of individual nodules by IP-CO2US surpassed that by IP-DSA, and was similar to that of IP-CTA. It was demonstrated that blood flow distribution (intrahepatic drug distribution) can be equally well grasped with IP-CO2US, which is a simple and convenient method, as with IP-RI angiography. It was also suggested that IP-CO2US is useful in the evaluation of tumor vascularity and the effect of therapy.

Antineoplastic Agents↗
PubMed1993

Immunocytochemical localization of rat substance P receptor in the striatum.

A trp E fusion protein containing a C-terminal portion of the rat substance P receptor (SPR) was expressed in bacteria and used to produce an antibody. The antibody specifically reacted with SPR expressed in a mammalian cell line and rat striatum. Light and electron microscope analyses of the rat striatum revealed intense SPR-like immunoreactivity in neuronal somata and dendrites. These immunoreactive neurons constituted approximately 3% of the total population of striatal neurons; they were putative interneurons of large and medium-sized aspiny type.

Animals↗
PubMed1993

[Usefulness of superparamagnetic iron oxide particles in the detection of hepatocellular carcinoma by MR imaging].

Eight patients with histologically or clinically diagnosed hepatocellular carcinoma and a total of 23 nodules were studied. SE 2000/20 (PDW-SE), SE-2000/80 (T2W-SE), SE 500/20 (T1W-SE), GRE 167/13/70 degrees (T1W-GE), and GRE 167/13/15 degrees (T2*W-GE) were used. Using each pulse sequence the pre-and post-contrast detection rates of the 23 nodules visualized by CT arterial portography (CTAP) were compared. With plain MRI, the detection rates were PDW-SE: 48%, T2W-SE: 74%, T1W-SE: 52%, T1W-GE 48% and T2*W-GE: 48%. After the administration of contrast medium all pulses sequences showed enhanced detection rates: 100%, 83%, 87%, 91%, and 96% respectively. Superparamagnetic iron oxide particle enhanced MRI showed a high detection rate comparable to CTAP, suggesting that this agent can make a major contribution to the diagnosis of HCC, particularly the detection of small HCC.

Carcinoma, Hepatocellular↗
PubMed1993

[Study on the evaluation of recurrence of HCC and the effect after transcatheter hepatic arterial embolization--fluctuations in AFP values].

To determine the usefulness of alpha-fetoprotein (AFP) in determining recurrence of HCC after interventional angiography (IVA) and to define the relation between AFP and the imaging diagnosis of HCC recurrence, changes in AFP values in 160 patients with hepatocellular carcinoma who were treated by IVA > or = two times were classified into four patterns: A: the AFP value was decreased after the first IVA, increased at recurrence and decreased again after the second IVA; B: the AFP value was unchanged after the first IVA, but increased at recurrence and decreased after the second IVA; C: the AFP value was decreased after the first IVA, but was not increased at recurrence; D: the AFP value showed no change. The frequency of each AFP pattern and the diagnosis of recurrence by AFP were determined. The relation between tumor type and AFP was defined. Pattern A was the most frequently detected. In 62.6%, AFP was increased at recurrence (A and B), and there was a positive correlation between changes in the AFP value and the findings of imaging diagnosis. In another 37.5%, AFP was not increased at recurrence (C and D), and therefore, the diagnosis of HCC recurrence by imaging methods was very important.

Aged↗
PubMed1993

Conformation of deltorphin-II in membrane environment studied by two-dimensional NMR spectroscopy and molecular dynamics calculations.

Two-dimensional homonuclear Hartmann-Hahn spectroscopy and NOESY (nuclear Overhauser effect and exchange spectroscopy) 1H-NMR techniques have been used to obtain complete proton resonance assignments and to perform a conformational investigation of deltorphin-II (Tyr-D-Ala-Phe-Glu-Val-Val-Gly-NH2), a naturally occurring delta-selective opioid peptide, in the membrane-mimetic micelles of perdeuterated dodecylphosphocholine. This was done in order to examine conformational characteristics that would be closely related to the selectivity towards the delta-opioid receptor. With the use of the proton-proton distances derived from NOESY measurements, 50 possible three-dimensional structures were generated by means of distance-geometry calculations, and 25 of them were subjected to the molecular-dynamics simulations of 10 ps, which were energetically constrained for the NOE interproton distances. Most of the possible conformers simulated showed a common feature such that the conformation of deltorphin-II is characterized by the S-shaped back-bone structure in which the turn conformation of the Val-Val-Gly-NH2 sequence is located under the helically folded conformation of the N-terminal Tyr-D-Ala-Phe-Glu sequence. The possible relationship between this conformational characteristic and the delta-opioid-receptor selectivity has been discussed.

Amino Acid Sequence↗
PubMed1993

Collateral projections of trigeminal ganglion neurons to both the principal sensory trigeminal and the spinal trigeminal nuclei in the rat.

Employing a combination of fluorescent retrograde double labelling and immunofluorescence histochemistry for substance P (SP) and calcitonin gene-related peptide (CGRP), we examined collateral projections from single neurons in the trigeminal ganglion (TG) of the rat to both the principal sensory trigeminal nucleus (Vp) and the oral, interpolar or caudal subnuclei of the spinal trigeminal nucleus (Vo, Vi or Vc). In the rats that were unilaterally injected with fast blue (FB) into the Vp and with diamidino yellow (DY) into the Vo, Vi or Vc, neurons labelled with FB and/or DY were observed in the TG ipsilateral to the injections. Of the labelled TG neurons, about 2% were double labelled with both tracers in the rats that were injected with FB into the Vp and with DY into the Vo or Vi, and about 10% were double labelled in the rats that were injected with FB into the Vp and with DY into the Vc. The results indicate that TG neurons sending their axons to the Vp project, by way of axon collaterals, to the Vc more frequently than to the Vo or Vi. Some of the TG neurons double labelled with FB and DY exhibited SP- or CGRP-like immunoreactivity (LI): Of the TG neurons that were double labelled with FB injected into the Vp and with DY injected into the Vo, Vi or Vc, about 38%, 49% and 42%, respectively, displayed SP-LI, and about 54%, 58% and 59%, respectively, showed CGRP-LI.(ABSTRACT TRUNCATED AT 250 WORDS)

Afferent Pathways↗
PubMed1993

Distribution of the messenger RNA for a metabotropic glutamate receptor, mGluR2, in the central nervous system of the rat.

Distribution of the messenger RNA for a metabotropic glutamate receptor, mGluR2, which is coupled to the inhibitory cyclic AMP cascade, was investigated in the central nervous system of the adult rat by in situ hybridization. Transcripts of mGluR2 were specifically localized to neuronal cells of the brain. Although the hybridization signals were widely distributed in the brain, the most prominent expression of mGluR2 messenger RNA was seen in Golgi cells of the cerebellum. Marked expression of mGluR2 messenger RNA was further observed in the mitral cells of the accessory olfactory bulb, neurons in the external part of the anterior olfactory nucleus, and pyramidal neurons in the entorhinal and parasubicular cortical regions. The granule cells of the accessory olfactory bulb, and many pyramidal and non-pyramidal neurons in the neocortical, cingulate, retrosplenial and subicular cortices, were moderately labeled. All of the granule cells in the dentate gyrus were also labeled moderately, whereas no significant hybridization signals were detected in Ammon's horn. In the basal forebrain regions, moderately labeled neurons were distributed in the triangular septal nucleus, in the lateral, basolateral and basomedial amygdaloid nuclei, and in the medial mammillary nucleus. Weakly labeled neurons were sparsely scattered in the striatum, globus pallidus, ventral pallidum and claustrum. The subthalamic nucleus was also labeled weakly. No significant labeling was found in the entopeduncular nucleus and substantia nigra. In the thalamus, moderately labeled neurons were distributed in the anterodorsal, anteromedial, ventromedial, intralaminar and midline nuclei; the ventrolateral part of the anteroventral nucleus and the rostral pole of the ventrolateral nucleus also contained moderately labeled neurons. No significant labeling was found in the thalamic reticular, submedius, ventroposterior, lateral geniculate and medial geniculate nuclei. In the lower brainstem, labeling was generally weak. No significant hybridization signals were found in the spinal cord. Some neurons in the inner part of the inner nuclear layer of the retina and some retinal ganglion cells were labeled moderately. The pattern of distribution of mGluR2 messenger RNA revealed in the present study indicates specific roles of mGluR2 in the glutamatergic system in the brain.

Animals↗
PubMed1993

Molecular dynamics simulation of 1,2-dilauroyl-L-phosphatidylethanolamine binding to phospholipase A2: an attempt to explain the selective hydrolysis of substrate fatty acid ester at position 2.

To improve our understanding of why phospholipase A2 (PLA2) specifically catalyzes the hydrolysis of the fatty acid ester bond at position 2, not at position 1, of 1,2-diacyl-3-sn-phosphoglycerides, the binding of each fatty acid chain of 1,2-dilauroyl-L-phosphatidyl-ethanolamine (DLPE), a natural substrate, to bovine pancreas PLA2 was examined by molecular dynamics (MD) simulations. Two different binding modes were considered, i.e., the respective hydrocarbon chains of 1- and 2-lauroyl fatty acid esters were located at the PLA2 binding sites usually observed in the complex crystals (Form A2) and at the reverse sites (Form A1). Although the total energies of both forms fluctuated within nearly the same range during the 80 ps MD simulations, the binding mode of DLPE to the PLA2 catalytic site through the coordination to Ca2+ was much more advantageous in Form A2 than that in Form A1; significant deviation of the Ca2+ position from its starting structure was observed in the MD simulation of Form A1. The result suggests the importance of Ca2+ in the selective recognition and catalytic function of PLA2 toward the 2-positioned fatty acid ester of phosphoglyceride substrates.

Animals↗
PubMed1993

Incomplete interlobar fissures: bronchovascular analysis with CT.

Thin-section computed tomographic scans of both lungs in 154 patients, including seven cadavers, with lung cancer (n = 37), diffuse (n = 32) or inflammatory (n = 30) lung disease, other proved or suspected disease (n = 23), or healthy lungs (n = 32) were analyzed to determine the frequency of incomplete interlobar fissure (IIF). An IIF was defined as a discontinuous linear shadow that remained in contact with the chest wall. An IIF was found in 128 of 154 right lungs (83.1%) and 77 of 154 left lungs (50.0%). Some bronchovascular structures crossed or passed through two contiguous lobes in the fused area. The most common bronchovascular structure associated with an IIF was a pulmonary vein; this association was found in 87 right lungs (56.5%) and 20 left lungs (13.0%). An IIF was traversed by a pulmonary artery in only seven right lungs and 13 left lungs or by a bronchus in only three lungs. It is concluded that recognition of an IIF might improve understanding of the spread of pulmonary disease.

Bronchi↗
PubMed1993

Cytotoxic effect of hinokitiol and tropolone on the growth of mammalian cells and on blastogenesis of mouse splenic T cells.

Hinokitiol (I) and tropolone (II) showed characteristic cytotoxic effects in vitro on five kinds of human and murine cell lines and blastic lymphocytes from mouse splenocytes. The cytotoxic effect of I on the growth of murine and human tumor cell lines, including RL male-1, MH134, HL60, K562 and KATO-III was definite when examined by thymidine incorporation into DNA and its 50% inhibitory concentration (IC50) on all cells was 0.3-0.6 microgram/ml. Compound II also showed comparable cytotoxic effects on these cell lines, indicating a little lower activity when compared to I. Furthermore, I and II also completely suppressed the [3H]thymidine ([3H]TdR) incorporation of mitogen-induced blastic lymphocytes. The suppressive activity on mouse lymphocyte proliferative response to concanavaline-A was also found with both compounds at a low concentration of 0.32 microgram/ml. As compound I is known to be of fairly low toxicity (LD50: 453 + 24 mg/kg in mice), the antitumor and immuno-suppressive effect of hinokitiol (I) should be further investigated.

Animals↗
PubMed1993

Structure-activity relationship of 3,3'-dihydroxy-alpha,beta-diethyldiphenylethane and its related compounds.

3,3'-Dihydroxy-alpha,beta-diethyldiphenylethane (I), 3,3'-dihydroxy-alpha,beta-diethylstilbene (II), hexestrol (III) and diethylstilbestrol (IV) have already been reported to show hypotensive effects on rats and exhibit phytogrowth-inhibitory activities. We have proposed that two phenolic hydroxyl groups in these compounds are necessary for the biological activities, and a structure-activity relationship for I-related compounds was accomplished using molecular-mechanics (MM) calculations. As a result, the following three findings were obtained; 1) the minimized conformational energy obtained from MM calculations, which is a parameter expressing the molecular stability, showed a relatively high correlation with the biological activities, 2) as results of quantitative structure-activity relationship (QSAR) analyses, the combination of the distance between two phenolic hydroxyl oxygens led to the regression equations with high correlation values, and 3) the idealized molecular model of the most active compound (I) showed the highest stability and had a particular conformation which differed from the other compounds (II-IV).

Animals↗