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H Ojima

Publications and source records attributed to H Ojima.

At least 19 recordsLinked to original sources
PubMed1996

Dual termination modes of corticothalamic fibers originating from pyramids of layers 5 and 6 in cat visual cortical area 17.

Terminal morphology of corticothalamic fibers originating from cat area 17 was examined. Injections of an anterograde axonal tracer, phaseolus vulgaris leucoagglutinin (PHA-L), in area 17 resulted in labeling of small boutons in the dorsal lateral geniculate, perigeniculate, and thalamic reticular nuclei and in labeling of large boutons in the lateral nucleus of lateral posterior-pulvinar, ventral lateral geniculate, and pulvinar nuclei. Since it is well known that the dorsal geniculate nucleus is a major corticothalamic target for layer 6 pyramids and the lateral posterior-pulvinar complex is that for layer 5 pyramids, the findings indicate that layer 5 pyramids in cat area 17 project axons ending with large boutons, while layer 6 pyramids project those ending with small boutons.

Animals↗
PubMed1996

Synaptic relationships between axon terminals from the mediodorsal thalamic nucleus and layer III pyramidal cells in the prelimbic cortex of the rat.

A combined study of anterograde axonal degeneration and Golgi electron microscopic technique was designed to examine the distribution and density of axon terminals from the mediodorsal thalamic nucleus (MD) over layer III pyramidal cells in the prelimbic cortex of the rat. The reconstructive analysis of serial ultrathin sections of gold-toned apical and basal dendrites of layer III pyramidal cells showed that degenerating thalamocortical axon terminals from MD formed asymmetrical synaptic contacts predominantly with dendritic spines of the identified basal dendrites as well as apical dendrites. There was little difference in the numerical density of thalamocortical synapses from MD per unit length of both apical and basal dendrites.

Animals↗
PubMed1996

Linear systems analysis of activating processes of complement system as a defense mechanism.

The complement system is an important element of the host defense mechanism, although its kinetics and characteristics as a system are still unclear. We have investigated its temporal changes and system properties from the view point of system engineering. The temporal changes of sequential activating processes of the system were expressed by 26 non-linear differential equations using reported values of rate constants and serum concentration for each component. The intermediate products in the activating processes increased parabolically while the membrane attack component as the final product, increased linearly. The little change in inactive precursors afforded validity for system linearization. Linear systems analysis revealed that the system which was insensitive to the changes in rate constants was unstable. The system became stable when the feed-back input from the final product was set to operate on the first step of the activating processes. Seven uncontrollable variables were insensitive to changes in rate constants or system optimization that minimized the changes in concentrations of components in the complement system. The singular values of the complement system were reduced and the impulse responses of the system were improved when the system was optimized. When stronger minimization was imposed on the changes of concentration of the components in the complement system, the singular values were reduced more, the magnitude of the impulse responses was depressed further and the responses terminated earlier than those when the elements in the weighting matrix of concentration of the components were set to be unity. By this potent minimization, the influences of changes in rate constants on the singular values were diminished. The present theoretical analysis is presented to evaluate the ability of defense mechanism of complement system.

Animals↗
PubMed1995

Electron microscopic evidence that axon terminals from the mediodorsal thalamic nucleus make direct synaptic contacts with callosal cells in the prelimbic cortex of the rat.

A combined study of anterograde axonal degeneration and HRP retrograde labeling has shown that there exist monosynaptic connections between afferent fibers from the mediodorsal thalamic nucleus (MD) and callosal cells in the prelimbic cortex of the rat. Degenerating axon terminals from MD made asymmetrical synaptic contacts with dendritic spines from apical dendrites of layer III pyramidal cells that were retrogradely labeled with HRP after its injection into the prelimbic cortex contralateral to MD lesions.

Afferent Pathways↗
PubMed1995

Two classes of cortical neurones labelled with Vicia villosa lectin in the guinea-pig.

Cell surface substance(s) containing terminal N-acetylgalactosamine (GaINAc) was localized in the cerebral cortex of the guinea-pig. Vicia villosa and Glycine max, both specific to GaINAc, labelled the surface of the cell body of multipolar and triangular neurones. The labelling extended to the apical dendrite and axon initial segment in the triangular neurones. They were distributed exclusively in layer 5. Most of the labelled multipolar neurones contained a calcium-binding protein, parvalbumin (Pv), while none of the triangular neurones did. The findings indicate that, in the guinea-pig, pyramidal neurones as well as non-pyramidal interneurones are enwrapped by GaINAc-containing substances and suggest that this enwrapping does not seem to be linked to Pv production.

Aging↗
PubMed1993

[Dendritic arborization patterns of interneurons labeled with a lectin, Vicia villosa, in rat cerebral cortex: studies by intracellular injection of lucifer yellow using aldehyde-fixed slices].

In order to characterize the dendritic field of a number of interneurons in the cerebral cortex, the labeling of extracellular sugar chains which define a subset of interneurons was combined with the subsequent intracellular filling of dyes in aldehyde-fixed tissue. Neurons whose cell body had been outlined by a lectin, Vicia villosa (VVA), which recognizes terminal N-acetylgalactosamine, were intracellularly injected with a fluorescent tracer, Lucifer yellow (LY), in the rat parietal cortex under direct visualization. After immunohistochemical detection of LY, somal morphology and the dendritic fields of injected neurons were reconstructed from serial sections and characterized in each of the layers II/III, IV, V and VI. Multipolar, flask-shaped and bitufted somata were VVA-positive. Multipolar neurons with round soma and spherical dendritic field were found in layers II/III, IV and V, while those with vertically elongated dendritic fields were found in layer VI. Cell bodies were located roughly in the center of the spherical or cylindrical dendritic fields. Neurons with apparently multipolar but flask- or pear-shaped soma were found frequently in layer IV, and much less frequently in layer II/III and VI. The majority of the dendrites originated from the neck portion of flask and formed a roughly spherical dendritic field with the cell body located more or less eccentrically. Some neurons in layer IV had an oval, somewhat vertically elongated soma and displayed a typical bitufted dendritic arborization pattern with vertically elongated dendritic fields. The overall dendritic field sizes of the cells gradually increased at deeper layers of the cortex.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldehydes↗
PubMed1992

Ranges of dynamic motion of the wrist in healthy young and middle-aged men.

The difference in the range of dynamic motion of the wrist between young and middle-aged men was studied. To analyse wrist function easily, a new quantitative evaluation technique for wrist circumduction using a biaxial flexible electrogoniometer was introduced. A phase plane was made from two-channel signals of the electrogoniometer, and the 'ROM (range of motion) Index' for wrist circumduction was defined. Twelve healthy young men (age 19-31 years) and twelve healthy middle-aged men (age 45-63 years) were studied. Under forearm fixed conditions, there was no difference of the ROM Index between the two age groups. A significant decrease of the ROM Index in the middle-aged group was found in the non-dominant wrists without forearm fixation. The four quadrantal analysis of wrist circumduction clarified that this difference appeared especially in the radiodorsal direction. These results suggest that in the middle-aged men, the motor function involving the radiocarpal and midcarpal joints does not decrease, but that for the proximal and distal radioulnar joints in the non-dominant side drops.

Adult↗
PubMed1989

Cholinergic innervation of the rat cerebellum: qualitative and quantitative analyses of elements immunoreactive to a monoclonal antibody against choline acetyltransferase.

Cholinergic innervation of the rat cerebellum was investigated immunohistochemically by using a monoclonal antibody against choline acetyltransferase. Immunoreactive structures included: 1) a subpopulation of mossy fibers and glomerular rosettes; 2) thin varicose fibers, which were closely associated with the Purkinje cell layer and also found in the molecular layer; and 3) relatively dense networks of varicose fibers distributing in the cerebellar nuclei. Quantitative analysis indicated that a great many immunoreactive rosettes were localized in lobules IXc and X, although their density in lobule X was approximately four times that in the lobule IXc. A considerable number of immunoreactive structures were also present in all other lobules. In the hemispheres they were confined to a zone immediately beneath the Purkinje cell layer, whereas in the vermis they were scattered throughout the granular layer. Most of the immunoreactive fibers found in the molecular layer coursed toward the pial surface and were distributed within the inner half of the molecular layer. In the cerebellar nuclei, portions of the medial nucleus and magnocellular portion of the lateral nucleus had moderately dense networks of immunoreactive fibers, whereas loose networks of fibers were observed in the posterior interposed nucleus. Other parts of the cerebellar nuclei contained a smaller number of varicose fibers.

Animals↗
PubMed1989

Effects of N-(2,6-dimethylphenyl)-2-(2-oxo-1-pyrrolidinyl)acetamide (DM-9384) on learning and memory in rats.

Effects of N-(2,6-dimethylphenyl)-2-(2-oxo-1-pyrrolidinyl) acetamide (DM-9384) on learning and memory were studied using four different experimental rat models. In electroconvulsive shock- or scopolamine-induced amnesia in the step-through passive avoidance task, DM-9384 improved both types of amnesia when administered before the training trial. Aniracetam also showed similar but somewhat weaker effects. Furthermore, in the scopolamine amnesia model, an improvement was confirmed with arecoline. The dose-response curves for these compounds were bell-shaped. In the shuttle box active avoidance task, DM-9384 administered daily 1 hr before each training session facilitated the acquisition process of the avoidance response. In addition, the experiment of light-dark discrimination task with positive reinforcement showed that this compound administered daily after each session slightly accelerated the acquisition process of the correct response. These results suggest an ability of DM-9384 to enhance cognitive functions.

Animals↗
PubMed1988

Changes in choline acetyltransferase immunoreactivity and the number of immunoreactive fibers remaining after lesions to the magnocellular basal nucleus of rats.

Electrolytic and kainic acid lesions of the magnocellular basal nucleus of rats caused a homogeneous reduction in the density of choline acetyltransferase (ChAT)-immunoreactive fibers in the frontal and parietal cortices. ChAT immunoreactivity of the remaining fibers after unilateral lesions was increased ipsilaterally within the deafferentated areas. The number of intact immunoreactive fibers was consistently low through the period from 7 days to 6 months after the lesion. A previous finding that biochemically measured ChAT activity in the lesioned side recovered to the contralateral level should be interpreted as an increase in the content of ChAT in terminal axons rather than fiber sprouting.

Animals↗
PubMed1988

Cholinergic innervation of the main and the accessory olfactory bulbs of the rat as revealed by a monoclonal antibody against choline acetyltransferase.

The main and accessory olfactory bulbs (MOB and AOB) of the rat were immunohistochemically stained with a monoclonal antibody against choline acetyltransferase (ChAT) in order to know the difference in the distribution patterns of cholinergic fibers between these two structures. A few ChAT-immunoreactive cell bodies were found in the superficial and middle parts of the external plexiform layer (EPL) of the MOB, in the granule cell layer (GCL) of the MOB, and in the GCL of the AOB. The frequency in appearance of these cells was 0.9 cells/section in the MOB and 0.3 cells/section in the AOB. While the glomerular layer (GL) and the superficial part of the EPL were most densely innervated in the MOB, the internal plexiform layer received the richest innervation in the AOB. There were no immunoreactive structures in the olfactory nerve layer of the MOB and in the vomeronasal nerve layer and glomerular layer of the AOB. In addition to a relatively homogenous distribution of cholinergic fibers in the MOB and AOB, there were several foci of very dense network of immunoreactive fibers at the posterior level of the OB. These foci formed a part of the modified glomerular complex that was recently identified using 2-deoxyglucose method and was presumed to be related to suckling behaviour in the neonatal rat.

Animals↗
PubMed1988

Immunohistochemical conditions for staining choline acetyltransferase-containing axon terminals in the rat.

Immunohistochemical conditions for staining cholinergic axon terminals using a commercially available anticholine acetyltransferase (anti-ChAT) monoclonal antibody were determined in the rat. A number of variations of procedures including fixative composition, fixation time, and incubation time and temperature in the anti-ChAT antibody solution were tested. Optimal procedures for minimizing the chance of negative staining of ChAT-containing axon terminals consisted of perfusion with a mixture of 4% paraformaldehyde and 0.2% glutaraldehyde for 3 min followed by a fixative containing only 4% paraformaldehyde for 10 min, and reaction with the anti-ChAT antibody for 2 days at 37 C. The distribution patterns of axon terminals stained in the cerebral cortex and the hippocampal formation were comparable to those reported by other investigators using different monoclonal antibodies.

Animals↗
PubMed1984

The trajectory of mitral cell axons in the rabbit olfactory cortex revealed by intracellular HRP injection.

The projection of the axon and axon collaterals of mitral cells to the olfactory cortex was studied in the rabbit by intracellular staining with horseradish peroxidase (HRP). The stained mitral cell axons were reconstructed from the soma to the most caudal portion of the anterior piriform cortex (aPC). Single mitral cells projected to cytoarchitectonically different areas of the olfactory cortex, i.e., the anterior olfactory nucleus (AON), the aPC, and the olfactory tubercle (OT). All the stained mitrall cells projected to both the AON and the aPC, and about one-fourth of the mitral cells projected to the OT. At the surface of the AON and the aPC, the main axon running in the lateral olfactory tract (LOT) gave off several thin collaterals at various intervals. The collaterals did not project evenly in each area but typically formed patchy terminal arbors which tended to be elongated anteroposteriorly. In both the AON and the aPC, each single mitral cell formed several terminal arbors in layer Ia. The axon collaterals innervating the OT showed two types of projection patterns. One type of collateral was emitted from the main axon within the olfactory bulb, coursed through the ventro-medial portion of the olfactory peduncle without joining the main mass of the LOT and terminated mainly in the medial portion of the OT. The other type of collateral emerged from the main axon in the LOT, coursed medioposteriorly, and projected to the lateral portion of the OT. Although individual mitral cells projected to several parts of the olfactory cortex, the fact that they made dense terminal arbors in specific places in each area suggests that the bulbocortical connections are not diffuse but highly selective.

Animals↗
PubMed1984

Distribution of local axon collaterals of mitral, displaced mitral, and tufted cells in the rabbit olfactory bulb.

To determine the projection fields of intrabulbar axon collaterals, mitral, displaced mitral, and middle tufted cells in the rabbit olfactory bulb were stained by intracellular injection of HRP. The axon collaterals of mitral cells and displaced mitral cells were distributed exclusively within the granule cell layer (GrL). Those of middle tufted cells were distributed mostly in the GrL and on rare occasions in the mitral cell layer. None of these collaterals entered the external plexiform layer. Axon collaterals of mitral cells, emitted at the depths of the GrL, were distributed widely from the deep portion to the most superficial portion of the GrL. Collaterals of displaced mitral cells were also emitted in the deep part, but they tended to be distributed more superficially in the GrL than mitral cells. Collaterals of middle tufted cells were released and distributed superficially in the GrL. The axon collaterals of these principal cells typically extended for a longer distance than the secondary dendrites, and they sometimes formed bushlike terminal arborizations. The results indicate that the projection fields of the axon collaterals of principal cells are spatially separated from the dendritic projection fields. This suggests that the output of these principal cells through the collaterals has a functionally different role from the output through the dendrites. The observation that the three types of principal cells differ in the distribution pattern of their axon collaterals in the GrL suggests that there is a functional separation of the sublayers in the GrL.

Animals↗
PubMed1983

Distribution of dendrites of mitral, displaced mitral, tufted, and granule cells in the rabbit olfactory bulb.

To determine the dendritic fields, mitral, displaced mitral, middle tufted, and granule cells in the rabbit olfactory bulb were stained by intracellular injection of HRP. The secondary dendrites of mitral cells were distributed mostly in the inner half of the external plexiform layer (EPL). Those of displaced mitral cells extended mainly into the middle and superficial sublayers in the EPL. The secondary dendrites of middle tufted cells were distributed mostly in the superficial portion of the EPL. Mitral cells extended their secondary dendrites in virtually all directions within a plane tangential to the mitral cell layer (MCL) and thus had a disklike projection field with a radius of about 850 microns. Displaced mitral cells had similar dendritic projection fields in the tangential plane but with somewhat distorted shapes. The secondary dendrites of middle tufted cells had a tendency to extend in particular directions. From the projection pattern of the gemmules on the peripheral processes, granule cells were classified into three types. Type I granule cells had gemmules both in the superficial and in the deep sublayers of the EPL. The peripheral processes of Type II granule cells were confined to the deep half of the EPL. The gemmules of Type III granule cells ere distributed in the superficial half of the EPL. The differing dendritic ramification among mitral, displaced mitral, and middle tufted cells suggests the separation of the dendrodendritic synaptic interactions with granule cells in different sublayers in the EPL. It also suggests a functional separation of the sublayers of the EPL.

Animals↗