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Y Shinoda

Publications and source records attributed to Y Shinoda.

At least 37 records · Page 2Linked to original sources
PubMed1999

Neural organization from the superior colliculus to motoneurons in the horizontal oculomotor system of the cat.

The neural organization of the superior colliculus (SC) projection to horizontal ocular motoneurons was analyzed in anesthetized cats using intracellular recording and transneuronal labeling. Intracellular responses to SC stimulation were analyzed in lateral rectus (LR) and medial rectus (MR) motoneurons and internuclear neurons in the abducens nucleus (AINs). LR motoneurons and AINs received excitation from the contralateral SC and inhibition from the ipsilateral SC. The shortest excitation (0.9-1.9 ms) and inhibition (1.4-2.4 ms) were mainly disynaptic from the SC and were followed by tri- and polysynaptic responses evoked with increasing stimuli or intensity. All MR motoneurons received excitation from the ipsilateral SC, whereas none of them received any short-latency inhibition from the contralateral SC, but some received excitation. The latency of the ipsilateral excitation in MR motoneurons (1.7-2.8 ms) suggested that this excitation was trisynaptic via contralateral AINs, because conditioning SC stimulation spatially facilitated trisynaptic excitation from the ipsilateral vestibular nerve. To locate interneurons mediating the disynaptic SC inputs to LR motoneurons, last-order premotor neurons were labeled transneuronally after injecting wheat germ agglutinin-conjugated horseradish peroxidase into the abducens nerve, and tectoreticular axon terminals were labeled after injecting dextran-biotin into the ipsilateral or contralateral SC in the same preparations. Transneuronally labeled neurons were mainly distributed ipsilaterally in the paramedian pontine reticular formation (PPRF) rostral to retrogradely labeled LR motoneurons and the vestibular nuclei, and contralaterally in the paramedian pontomedullary reticular formation (PPMRF) caudomedial to the abducens nucleus and the vestibular nuclei. Among the last-order premotor neuron areas, orthogradely labeled tectoreticular axon terminals were observed only in the PPRF and the PPMRF contralateral to the injected SC and seemed to make direct contacts with many of the labeled last-order premotor neurons in the PPRF and the PPMRF. These morphological results confirmed that the main excitatory and inhibitory connections from the SC to LR motoneurons are disynaptic and that the PPRF neurons that receive tectoreticular axon terminals from the contralateral SC terminate on ipsilateral LR motoneurons, whereas the PPMRF neurons that receive tectoreticular axon terminals from the contralateral SC terminate on contralateral LR motoneurons.

Animals↗
PubMed1999

HLA-DQB1 locus and the development of atrophic gastritis with Helicobacter pylori infection.

Helicobacter pylori is known to be involved in digestive diseases such as peptic ulcer, atrophic gastritis, and gastric cancer. It is supposed that the incidence of these digestive diseases associated with H. pylori is influenced by the strain diversity of H. pylori, factors involving the host or environment, and the duration of infection. In this study, we directed our attention to HLA, a host factor, and investigated the relation between HLA-DQB1 genotype of H. pylori-infected patients and the development of atrophic gastritis. HLA-DQB1 genotyping was performed by the polymerase chain reaction-restriction fragment length polymorphism method on 122 H. pylori-infected patients with atrophic gastritis and 28 uninfected Japanese controls. Infected patients with developed atrophic gastritis were classified as the open type and those with undeveloped atrophic gastritis as the closed type. To estimate the grade of atrophic gastritis reliably, histological and serological evaluations were also undertaken. The allele frequency of DQB1*0401 was significantly higher in the open-type group compared to either the closed-type or the uninfected group. These results suggest that immunogenic factors play an important role in the development of atrophic gastritis in H. pylori-infected patients, and that DQB1*0401 is a useful marker for determining susceptibility to this disease.

Adolescent↗
PubMed1998

Nitric oxide suppression reversibly attenuates mitochondrial dysfunction and cholestasis in endotoxemic rat liver.

This study aimed to examine whether nitric oxide (NO) plays a causal role in endotoxin-induced dysfunction of biliary transport. Rats were treated with intraperitoneal injection of endotoxin (O111B4, 4 mg/kg). At 2 hours, the liver was excised and perfused ex vivo with taurocholate (TC)-containing Krebs-Ringer solution under monitoring bile output and NO2 in the perfusate and tissue cyclic guanosine monophosphate (cGMP) levels as indices of NO production. The endotoxin treatment evoked a marked decrease in the bile acid-dependent bile formation concurrent with the increasing NO2 output, cGMP elevation, and a reduction of hepatic adenosine triphosphate (ATP) contents and oxygen consumption. Perfusion with 1 mmol/L aminoguanidine (AG), an inhibitor of inducible NO synthase, but not with L-nitroarginine methyl ester, an inhibitor of the constitutive form of the enzyme, significantly reversed the endotoxin-induced increment of the bile formation in concert with the recovery of oxygen consumption and ATP levels. Laser confocal microfluorography of the liver lobules using rhodamine 123 (Rh), a fluoroprobe sensitive to mitochondrial membrane potential, revealed that endotoxin elicited a significant mitochondrial dysfunction panlobularly. The AG administration reversed the endotoxin-induced decrease in mitochondrial membrane potential. Collectively, up-regulation of NO by inducible NO synthase accounts for a mechanism through which endotoxin impairs the bile formation, and its suppression serves as a therapeutic strategy for improvement of hepatobiliary function.

Animals↗
PubMed1998

Carbon monoxide as a regulator of bile canalicular contractility in cultured rat hepatocytes.

This study aimed to examine the mechanism(s) by which carbon monoxide (CO), a product of heme oxygenase reaction, controls the contractility of bile canaliculus (BC) in hepatocytes. When BCs associated with the couplet cells in cultured rat hepatocyte suspension were observed using time-lapse video microscopy, they exhibited periodical contractions with a most-probable interval of 6 minutes under our experimental conditions. The addition of 1 micromol/L zinc protoporphyrin IX (ZnPP), a potent inhibitor of heme oxygenase, to the culture medium elicited a 40% shortening of the interval time together with an increase in intracellular calcium concentrations, while the same concentration of iron protoporphyrin IX did not induce such changes. The production of CO, which was 0.5 nmol/h/10(8) cells in the absence of ZnPP, diminished to less than 0.1 nmol/h/10(8) cells upon application of ZnPP. The ZnPP-elicited increases in both contractile frequency and intracellular calcium concentrations were attenuated by the addition of 1 micromol/L CO or 50 micromol/L 1,2-bis(2-aminophenoxy) ethane-tetraacetate, a calcium chelator. Clotrimazole or metyrapone, inhibitors of cytochrome P450-dependent monooxygenase activities, also attenuated the ZnPP-induced elevation of the contractile frequency. On the other hand, intracellular cyclic guanosine monophosphate (cGMP) contents were not altered significantly by the application of ZnPP or by CO. These results indicate that CO generated by heme oxygenase controls the BC function by changing intracellular calcium concentrations presumably through a mechanism involving the cytochrome P450 reaction.

Animals↗
PubMed1998

Correlation of lining thickness and expression of alpha 2 and alpha 3 integrins within the epithelial lining of odontogenic cysts.

Using monoclonal antibodies, we performed immunohistochemical investigations of the expression of alpha 2, alpha 3 and beta 4 integrin subunits within the squamous epithelial linings of odontogenic cysts. Tissue samples consisted of both follicular cysts and odontogenic keratocysts from 15 patients. It was found that beta 4 integrin was expressed on the basement membrane regardless of the histological type of the cyst. The degree of immunostaining for alpha 2 and alpha 3 integrin expression corresponded to the thickness of the epithelial cyst wall. We found that the thickness of the epithelial lining of odontogenic cysts had a direct correlation with the expression of integrin molecules.

Antigens, CD↗
PubMed1997

Serial electron microscopic reconstruction of axon terminals on physiologically identified thalamocortical neurons in the cat ventral lateral nucleus.

The distribution of different types of terminals on different portions of single thalamocortical neurons (TCNs) was quantitatively investigated in the cat ventral lateral nucleus (VL) by the application of computer-assisted three-dimensional reconstruction from serial ultrathin sections. Single neurons in the VL were intracellularly penetrated with a glass micropipette filled with horseradish peroxidase (HRP), and were electrophysiologically identified as TCNs by their antidromic responses to stimulation of the motor cortex. These TCNs received monosynaptic excitation from the contralateral cerebellum. After electrophysiological identification, they were injected with HRP iontophoretically. The spatial distribution of terminals of different types on two identified TCNs was analyzed on serial ultrathin sections, some of which were stained by a postembedding immunogold technique by using a gamma-aminobutyric acid (GABA) antibody. Terminals that synapsed on the injected cells were categorized as LR terminals (GABA-negative large axon terminals containing round vesicles), SR terminals (GABA-negative small axon terminals containing round vesicles), P terminals (GABA-positive axon terminals of various sizes containing pleomorphic vesicles), or PSDs (presynaptic dendrites). The order of dendritic branches of labeled TCNs was determined by computer-assisted reconstruction from serial sections. LR terminals made contacts mainly with proximal dendrites of TCNs. SR terminals made contacts predominantly with distal dendrites, and were never found on somata or primary dendrites. P terminals were observed on somata and on every portion of the dendritic trees. Synapses formed by PSDs were concentrated on the proximal dendrites and sometimes formed synaptic triads with LR terminals. Only a few terminals were found on somata, all of which were P type. Therefore, terminals belonging to different classes were not uniformly distributed on the somata and dendrites of single TCNs. These results suggest that terminals originating from different sources may preferentially contact specific regions of TCNs in the VL, and their topographical locations reflect the electrophysiological response properties of the TCNs.

Animals↗
PubMed1997

Hemangiopericytoma of the sigmoid mesentery: report of a case with immunohistochemical findings.

Hemangiopericytoma has been described in various sites in the body but only rarely in the mesocolon. This report describes the clinical course of an 83-year-old man whose mesosigmoidal tumor (hemangiopericytoma) was resected on 11 November 1994. Immunostaining was done with the following primary antibodies: alpha-actin, vimentin, factor VIII-related antigen, chromogranin, and S-100. Staining for factor VIII-related antigen was strongly positive in the endothelial cells of the capillaries, but negative in the tumor cells. The tumor cells contained immunoreactive vimentin, but demonstrated no alpha-actin, chromogranin, or S-100. Since the operation, the patient has been disease-free for 11 months.

Actins↗
PubMed1997

Endothelial-derived nitric oxide preserves anticoagulant heparan sulfate expression in cultured porcine aortic endothelial cells.

Nitric oxide (NO) has been shown to inhibit platelet adhesion and aggregation, but there are no reports on its interaction with the coagulation system. We investigated the effect of the L-arginine analogues, N-nitro-L-arginine (LNA), N(G)-nitro-L-arginine methyl ester (L-NAME), and N(G)-monomethyl-L arginine (L-NMMA), competitive inhibitors of NO production, on endothelial-surface heparan sulfate. Addition of LNA to porcine aortic endothelial cells reduced 125I-labeled antithrombin III binding to the cell surface heparan sulfate in a dose- and time-dependent fashion. Significant inhibition was observed with 1 mM LNA, and the maximal suppression (-50% of control) occurred at 10 mM LNA after 12 h. L-NAME (1 mM) and L-NMMA (1 mM) also significantly inhibited the antithrombin III binding. The iron chelator desferrioxamine significantly prevented the reduction of antithrombin III binding to LNA-treated cells. We further investigated the effect of L-NAME on intracellular oxidative stress of endothelial cells using a hydroperoxide-sensitive fluorochrome, carboxy-dichloro-dihydrofluorescein diacetate bisacetoxymethyl ester probe, and revealed that inhibition of NO synthesis by L-NAME led to a marked increase in intracellular oxidative stress. These results demonstrated that the prolonged inhibition of NO synthesis in porcine aortic endothelial cells decreases the expression of anticoagulant heparan sulfate on endothelial cells through the increase in intracellular oxidative stress, perhaps comprising another mechanism by which NO affects the coagulation system in the vasculature.

Animals↗
PubMed1997

Cerebellar input to corticothalamic neurons in layers V and VI in the motor cortex.

To investigate whether corticothalamic (CT) neurons in the motor cortex (Mx) receive cerebellar input via the ventroanterior-ventrolateral nucleus of the thalamus (VA-VL), we recorded intracellular potentials from neurons in the Mx of anesthetized cats and examined effects of stimulation of the VA-VL and the brachium conjunctivum on them. After this electrophysiological identification, horseradish peroxide (HRP) was injected iontophoretically into the recorded neurons for morphological analysis. We identified 34 neurons as CT neurons by their antidromic response to stimulation of the VA-VL, of which 13 were layer VI CT neurons and 21 were layer V CT neurons. A majority of the CT neurons of both layers VI and V received monosynaptic excitatory postsynaptic potentials (EPSPs) from the VA-VL and di- or polysynaptic EPSPs from the cerebellum. The laminar distribution and morphological characteristics of single CT neurons receiving cerebellar input were analyzed on 19 HRP-labeled CT neurons. Eight layer V and six layer VI CT neurons were reconstructed from serial sections. All the reconstructed layer VI CT neurons were modified pyramidal neurons whose apical dendrites ended in layer III or V, and all the stained layer V CT neurons were typical pyramidal neurons, although the laminar and tangential distribution of recurrent collaterals of these neurons varied from neuron to neuron.

Animals↗
PubMed1997

Endogenous carbon monoxide suppression stimulates bile acid-dependent biliary transport in perfused rat liver.

This study aimed to investigate whether carbon monoxide (CO), a product of heme oxygenase that degrades protoheme IX, serves as an endogenous modulator for biliary transport. To that end, effects of zinc protoporphyrin IX (ZnPP), a heme oxygenase inhibitor, on the biliary transport were tested in perfused rat liver. Perfusion of 1 microM ZnPP abolished detectable levels of CO in the venous perfusate and increased bile acid-dependent bile output accompanying an increased secretion of bile salts. The ZnPP-induced choleresis coincided with a reduction of tissue guanosine 3',5'-cyclic monophosphate (cGMP) levels and a decrease in vascular conductance. On administration of 2.5 microM CO, ZnPP-elicited choleresis, decreases in vascular conductance, and cGMP levels were all attenuated. Treatment with 1 microM 8-bromoguanosine 3',5'-cyclic monophosphate (8-BrcGMP) partly attenuated the ZnPP-induced choleresis in concert with repression of vascular conductance. Furthermore, treatment of the liver with methylene blue, a guanylate cyclase inhibitor, evoked a choleresis similar to that induced by ZnPP. Thus endogenous CO suppression stimulates the biliary transport in part through a cGMP-dependent mechanism.

Animals↗
PubMed1997

Input patterns and pathways from the six semicircular canals to motoneurons of neck muscles. II. The longissimus and semispinalis muscle groups.

To reveal patterns of input from the six semicircular canals to motoneurons of various neck muscles and their relationship to the mechanical actions of individual neck muscles, patterns of input to neck motoneurons of the longissimus and the semispinalis muscle groups were investigated in the upper cervical spinal cord of anesthetized cats. Intracellular potentials were recorded from motoneurons of the longissimus muscle group (obliquus capitis superior muscle, OCS; splenius muscle, SPL; longissimus muscle, LONG) and the semispinalis muscle group (biventer cervicis muscle, BIV; complexus muscle, COMP), and effects of separate electrical stimulation of the six ampullary nerves on them were analyzed in each preparation. Neck motoneurons usually received convergent inputs from all of the six ampullary nerves, and motoneurons that supplied a particular muscle had a homogeneous pattern of input from the six ampullary nerves. Two different patterns of input were identified for motoneurons of these two muscle groups; one pattern for motoneurons of the longissimus muscle group and the other pattern for motoneurons of the semispinalis muscle group. Motoneurons of the OCS, the SPL, and the LONG muscles received excitation from the three contralateral ampullary nerves and inhibition from the three ipsilateral ampullary nerves. BIV and COMP motoneurons received excitation from the bilateral anterior canal nerves (ACNs) and the contralateral canal nerve (LCN) and inhibition from the bilateral posterior canal nerves (PCNs) and the ipsilateral LCN. Latencies of postsynaptic potentials (PSPs) evoked by stimulation of each of the six ampullary nerves indicated that the earliest component of excitatory PSPs (EPSPs) and inhibitory PSPs (IPSPs) was disynaptic in these motoneurons. However, trisynaptic IPSPs were evoked by stimulation of the contralateral PCN in a considerable number of BIV and COMP motoneurons. In OCS, SPL, and LONG motoneurons, all of the excitation from the contralateral and all of the inhibition from the ipsilateral ampullary nerves were mediated through the ipsilateral medial longitudinal fascicle (MLF). In BIV and COMP motoneurons, disynaptic excitation from the contralateral ACN and LCN and disynaptic inhibition from the ipsilateral LCN and bilateral PCNs were mediated through the ipsilateral MLF, whereas disynaptic excitation from the ipsilateral ACN was mediated through the ipsilateral lateral vestibulospinal tract. The patterns of semicircular canal input to neck motoneurons of these two muscle groups are related closely to the mechanical actions of the individual neck muscles and the optimal stimulus to the semicircular canals such that the connections will tend to stabilize head positions in response to head perturbations.

Animals↗
PubMed1997

Origin of auditory brainstem responses in cats: whole brainstem mapping, and a lesion and HRP study of the inferior colliculus.

In order to identify the origin of five waves of auditory brainstem responses (ABRs) in cats, we designed three experiments. In particular, we focused on the inferior colliculus (IC). Experiment 1: Evoked potential maps of the frontal sections of the brainstem from the level of the cochlear nuclei to the level of the ICs were constructed from the results of whole brainstem field-potential analysis comparing ABR peaks. Experiment 2: Both ICs were aspirated and the brainstem and midbrian were transected along the midline. Experiment 3: HRP was injected to the central nucleus of the IC to cause phase reversal of field potentials, and localization of brainstem auditory neurons projecting to the IC was studied. The results of these experiments suggest that each wave of the ABR is elicited from multiple sources of auditory brainstem nuclei and tracts only.

Animals↗
PubMed1996

Morphology of axon collaterals of single climbing fibers in the deep cerebellar nuclei of the rat.

Projection of inferior olive (IO) neurons to the deep cerebellar nuclei (CN) was investigated in the rat by reconstructing single axons that were labeled with biotinylated dextran amine injected into the IO. All reconstructed terminal arborizations in the CN (n = 18) arose as collaterals from climbing fibers (CFs). One to six nuclear collaterals were given off from each of six CFs that were reconstructed along the nearly entire pathway backward from cortical terminal arborizations to the IO. Nuclear collaterals were much thinner (0.2-0.3 micron in diameter) than stem axons projecting to Purkinje cells (0.7-1.4 microns). The number of swellings per a single nuclear collateral ranged from 24 to 118 (n = 18). Terminal arborizations of nuclear collateral originating from a single CF spread for some hundreds of micrometers and occupied a localized portion within the CN.

Animals↗
PubMed1996

Projection pattern of single corticocortical fibers from the parietal cortex to the motor cortex.

Arborization of single corticocortical (CC) axons projecting from the parietal cortex to the motor cortex (Mx) was analysed using an intraaxonal staining technique in the cat. Stem axons arising from cell bodies in area 5 ramified repeatedly into numerous terminal branches in the Mx, forming 2-6 patches (0.2-0.8 mm in diameter) separated by a terminal-free gap. Axon terminals were distributed mainly in layers II and III and sparsely in layers V, VI and I. This feature is quite similar to that of thalamocortical axons and other corticocortical fibres. Thus the patchy organization may be a basic input structure for afferents of the Mx and play a role in generation of adequate motor output patterns in the Mx.

Animals↗
PubMed1996

Morphology of single axons of tectospinal neurons in the upper cervical spinal cord.

Morphology of single axons of tectospinal (TS) neurons was investigated by intraaxonal injection of horseradish peroxidase (HRP) at the upper cervical spinal cord of the cat. TS axons were electrophysiologically identified by their direct responses to stimulation of the contralateral superior colliculus (SC). None of these axons responded to thoracic stimulation at Th2. Three-dimensional reconstructions of the axonal trajectories were made from 20 well-stained TS axons at C1-C3. Cell bodies of these axons were located in the intermediate or deep layers of the caudal two-thirds of the SC. Usually, TS axons had multiple axon collaterals, and up to seven collaterals were given off per stem axon [2.7 +/- 1.6 (mean +/- S.D.); n = 20]. Collaterals had simple structures and ramified a few times mainly in the transverse plane. The number of terminals for each collateral was small. These collaterals terminated in the lateral parts of laminae V-IX, mainly in laminae VI, VII, and VIII. There were usually gaps free from terminal arborizations between adjacent collaterals, because the rostrocaudal spread of each collateral (mean = 700 microns) was narrower than the intercollateral interval (mean = 2,500 microns). Seven of the 19 TS axons had terminals in the lateral parts of laminae V-VIII, with little projection to lamina IX, and the other 12 axons had terminals in lamina IX besides the projection to the lateral parts of laminae V-VIII. Axon terminals in lamina IX did not appear to make contacts with the somata or proximal dendrites of retrogradely labeled motoneurons, but contacts were found with the somata of counterstained interneurons in the lateral parts of laminae V-VIII. Three spinal interneurons (two in lamina VIII and one in lamina V at C1) that received monosynaptic excitation from the SC were stained, and their axonal trajectories were reconstructed. They had multiple axon collaterals at C1-C2 and mainly projected to laminae VIII and IX, with smaller projections to lamina VII. Many axon terminals of the interneurons were found in multiple neck motor nuclei, where some of them made contacts with retrogradely labeled motoneurons. The present finding provides evidence that the direct TS projection to the spinal cord may influence activities of multiple neck muscles, mainly via spinal interneurons, and may play an important role in control of head movement in parallel with the tectoreticulospinal system.

Animals↗
PubMed1996

Three-dimensional analysis of cerebellar terminals and their postsynaptic components in the ventral lateral nucleus of the cat thalamus.

Relationships among cerebellar terminals (CTs), dendrites of thalamocortical projection neurons (TCNs), and dendrites of local circuit neurons in the ventral lateral nucleus of the cat thalamus were analyzed quantitatively by observing several series of serial ultrathin sections and by using a computer-assisted program for the three-dimensional reconstruction from serial ultrathin sections. In pentobarbital-anesthetized cats, CTs were labeled either by injections of wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) into the cerebellar nuclei or by intra-axonal injection of HRP after electrophysiological identification. By using two series of 133 and 73 serial sections, mutual relationships between 43 WGA-HRP-labeled CTs and their postsynaptic structures were analyzed based on their synaptic specializations and shapes of synaptic vesicles. Thirty-nine of these CTs formed a synapse with one TCN dendrite, whereas only four CTs formed synapses with two TCN dendrites. These CTs also synapsed on dendrites containing pleomorphic synaptic vesicles (presynaptic dendrites). Single CTs synapsed on 0-6 presynaptic dendrites (2.2 +/- 1.5, N = 43) through their whole extents, and about 40% of these presynaptic dendrites that were contacted by CTs established synaptic contacts with the same TCN dendrites on which the CTs synapsed. Thus, a CT, a presynaptic dendrite, and a TCN dendrite formed a triadic arrangement. Triadic arrangements were identified in approximately 60% of these 43 CTs. However, they rarely had a glomerulus-like appearance, as described previously in the ventral lateral nucleus and other main thalamic relay nuclei. In another series of 83 and 43 serial sections along dendrites of TCNs, observations were focused on the triadic arrangement. Triadic arrangements were located evenly on the primary and secondary dendrites of TCNs. Computer-assisted three-dimensional reconstructions were made on one WGA-HRP-labeled CT and two intra-axonally labeled CTs (a bouton en passant and a bouton terminal) with their surrounding neuronal elements, and complex spatial arrangement of neuronal processes became obvious. These results provide the quantitative assessment of synaptic arrangements among CTs, presynaptic dendrites, and TCN dendrites and reveal their spatial interrelations in the cat ventral lateral nucleus.

Animals↗
PubMed1996

Four convergent patterns of input from the six semicircular canals to motoneurons of different neck muscles in the upper cervical cord.

This study was performed to investigate the pattern of input and the pathways from the six semicircular canals to motoneurons of various neck muscles in anesthetized cats. Intracellular postsynaptic potentials from neck motoneurons were recorded in response to electrical stimulation of the six ampullary nerves. The results showed that motoneurons of a particular neck muscle have a homogeneous convergent pattern of input from the six semicircular canals; there are four patterns of input from the six semicircular canals to motoneurons of various neck muscles; and the trisynaptic connection between the semicircular canal nerves and neck motoneurons was identified in addition to the disynaptic connection.

Action Potentials↗