PubMed Health⌕ Search

Biomedical subjects

S Masuko

Publications and source records attributed to S Masuko.

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

The structure of the brain-specific rat aldolase C gene and its regional expression.

The rat aldolase C gene was isolated from a rat genomic DNA library. This gene comprises 9 exons and spans 3590 base pairs. A single copy of the gene occurs per haploid rat genome. The initiation of transcription occurs at two different sites. The cellular localization of aldolase C mRNA was determined in the central nervous system along with aldolase A mRNA by in situ hybridization. The result indicates the predominant expression of this gene in Purkinje cells of the cerebellar cortex, where aldolase A mRNA was rather repressed.

Amino Acid Sequence↗
PubMed1991

Target-specific projections of intrinsic ganglionic neurons with different chemical codes in the canine larynx.

The distribution and origin of peptide-containing intrinsic nerve fibers within the larynx were examined by immunohistochemistry and denervation experiments in the dog. In the normal larynx, a dense network of vasoactive intestinal polypeptide (VIP)-immunoreactive (IR) fibers was seen around the acini of submucosal glands. VIP-, substance P (SP)-, or calcitonin gene-related peptide (CGRP)-IR fibers were seen in the walls of submucosal arteries, and VIP-, neuropeptide Y (NPY)-, or enkephalin (ENK)-IR fibers were seen around the arteries in the muscle tissue. Most of these peptide-IR fibers remained after bilateral denervation of the superior and inferior laryngeal nerves. Several small intrinsic ganglia were found along the peripheral branches of the laryngeal nerves. About 97% of the ganglionic neurons were VIP-IR; of these, 44% were immunoreactive to VIP alone, 22% to VIP and NPY, 13% to VIP and SP, 7% to VIP and ENK, and 14% to VIP, NPY and SP. These results reveal that the exocrine glands and blood vessels are innervated by the intrinsic ganglionic neurons and that subpopulations of ganglionic neurons with different chemical codes innervate specific target organs in the canine larynx.

Animals↗
PubMed1991

Role of the gag and pol genes of human immunodeficiency virus in the morphogenesis and maturation of retrovirus-like particles expressed by recombinant vaccinia virus: an ultrastructural study.

An ultrastructural study was performed on rabbit epithelial RK-13 cells and CD4+ human T lymphocyte lines infected with various recombinant vaccinia viruses (RVVs) expressing genes of human immunodeficiency virus (HIV): the mature p17 or p24 gag domain alone, the entire or truncated gag gene, the reverse transcriptase domain, or the gag-pol genes with a frameshift mutation. Cells infected with RVVs that produced the gag polyprotein with a predicted Mr of more than 48K showed budding and release of HIV-like particles into the extracellular space. These particles were not observed in cells expressing a truncated gag gene (p17 and p24 regions). Mature HIV-like particles were observed extracellularly when the entire gag gene and the protease region of the pol gene were expressed. In contrast, in cells infected with RVVs that contained the gag-pol gene with a frameshift mutation, neither recognizable budding structures nor extracellular HIV-like particles could be detected. These results suggest that the gag gene, particularly its 3' terminus, is necessary for the assembly of HIV particles. In addition, the protease region of the pol gene seems to be required for morphological maturation of HIV particles, but complete proteolytic cleavage of the gag protein may prevent bud formation.

Amino Acid Sequence↗
PubMed1990

Distribution of neuropeptide-like immunoreactive nerve fibers in the canine larynx.

The distribution of neuropeptide immunoreactive nerve fibers in the canine larynx was examined. In the epithelium of supra- and subglottic regions, a dense distribution of substance P (SP)- and calcitonin gene-related polypeptide (CGRP)-immunoreactive (IR) nerve fibers was observed. Some vasoactive intestinal polypeptide (VIP)-IR intraepithelial nerve fibers were also seen in the subglottic region. In the laryngeal glands, a dense distribution of VIP-IR nerve fibers with a few SP- and enkephalin (ENK)-IR nerve fibers were found around the acini. In the walls of arteries in the lamina propria, many VIP-, SP-, and CGRP-IR nerve fibers were seen, whereas neuropeptide Y-, ENK-, and VIP-IR nerve fibers were predominantly distributed around the arteries in the vocal muscle. In the free edge of the vocal cord, few immunoreactive nerve fibers were detected within the epithelium and around the arteries in the lamina propria. These results suggest that there are regional differences in the occurrence of peptides in nerve fibers innervating the epithelium and the blood vessels in the larynx and that the perception mechanism of the epithelium and the regulatory system of local blood flow are varied according to their location in the larynx.

Animals↗
PubMed1989

Do the ependymal cells contain vasoactive intestinal polypeptide?

Immunoreaction for vasoactive intestinal polypeptide (VIP) in the ependymal cells was investigated using two different commercially available polyclonal antisera for VIP. Immunostaining with an anti-VIP serum showed strong reaction products in the ependymal cells of the central canal and the third ventricle, in addition to immunoreactive neuronal elements in the spinal cord and in the suprachiasmatic nucleus. Staining of the ependymal cells was not reduced by preabsorption of the antiserum with synthetic VIP, while the immunoreactive neuronal elements disappeared. Such staining of the ependymal cells was not found using other antiserum.

Animals↗
PubMed1989

An immunohistochemical observation of polypeptides and monoamines in the nucleus preopticus medianus of the rat.

A detailed regional distribution of nerve cells and terminals immunoreactive to polypeptides or monoamines was examined in the 5 subdivisions (rostral, mid-dorsal, mid-ventral, caudo-dorsal and caudo-ventral parts) of the nucleus preopticus medianus (POMe) of the rat. In general, immunoreactive nerve cells and terminals are more numerous in the ventral parts of the middle and caudal POMe. Nerve cells immunoreactive to neurotensin (NT), Met-enkephalin-Arg6-Gly7-Leu8 (mENK8) or cholecystokinin-octapeptide (CCK8) are distributed throughout the POMe, while those immunoreactive to luteinizing hormone-releasing hormone (LHRH) are found in the rostral and middle POMe. Nerve cells immunoreactive to substance P (SP) are seen in the middle and caudal POMe and those immunoreactive to somatostatin (SRIF) are scattered in the middle part of the nucleus. The densities of nerve terminals immunoreactive to neuropeptide tyrosine, mENK8, SP or noradrenaline are high throughout the POMe, while nerve terminals immunoreactive to CCK8, LHRH, NT, SRIF or vasoactive intestinal polypeptide are moderate and those immunoreactive to calcitonin gene-related peptide, serotonin or dopamine are sparse. This varied distributional pattern of immunoreactive nerve cells and terminals suggests regional differences in function within the POMe.

Animals↗
PubMed1989

Coexistence of multiple peptides in small intensely fluorescent (SIF) cells of inferior mesenteric ganglion of the guinea pig.

Coexistence of peptides in the small intensely fluorescent cells was demonstrated by immunocytochemistry for met-enkephalin-Arg-Gly-Leu, vasoactive intestinal polypeptide, somatostatin, neuropeptide Y and dynorphin. In the extreme example, a single cell was immunoreactive to all 5 peptides examined. Four peptides coexisted in 8% and three peptides in 13% of SIF cells. In 10% of SIF cells no peptide immunoreactivity could be detected. The most prevalent peptide was met-enkephalin (in 46% of cells), then vasoactive intestinal polypeptide (45%), somatostatin (39%), neuropeptide Y (31%) and dynorphin (24%). Met-enkephalin and vasoactive intestinal polypeptide coexisted most commonly (25%).

Animals↗
PubMed1989

Coexistence of varying combinations of neuropeptides with 5-hydroxytryptamine in neurons of the raphe pallidus et obscurus projecting to the spinal cord.

The coexistence of varying combinations of substance P (SP), somatostatin (SOM), thyrotropin-releasing hormone (TRH) and met-enkephalin-Arg-Gly-Leu (ENK) with 5-hydroxytryptamine (5-HT) as semiquantitatively revealed by immunocytochemistry in neuronal perikarya of the raphe pallidus et obscurus in the guinea-pig was analyzed. SOM coexisted most frequently with 5-HT, followed by SP, ENK and TRH. Many 5-HT neurons were immunoreactive to 2 or more peptides such as SP/SOM, SOM/ENK, SP/ENK, SOM/TRH, SP/TRH or SOM/SP/ENK. Most of these neurons were shown to project to the spinal cord by retrograde HRP labeling combined with immunocytochemistry. After hemisection of the cervical spinal cord at the C5 level, ENK and 5-HT immunoreactive nerve terminals in the ipsilateral intermediolateral nucleus of the thoracic spinal cord were decreased in number. The results indicate that neurons in the raphe pallidus et obscurus projecting to the spinal cord can be classified into subpopulations according to which peptides coexist with 5-HT, and may have different functions.

Animals↗
PubMed1989

Autonomic neurons and paraneurons (SIF cells) in the sympathetic ganglia regulating guinea pig proximal colon: immunohistochemical studies.

Additional evidence for the existence of subclasses of SIF cells is described. Type II SIF cells in the inferior mesenteric ganglia contain enkephalin, vasoactive intestinal polypeptide (VIP), somatostatine (SOM), neuropeptide tyrosine (NPY), or dynorphin (DYN) in variable combinations in addition to noradrenalin. These transmitters or modulators can affect the autoreceptors of the SIF cell themselves or modify the synatpic transmission and the activity of sympathetic ganglionic neurons through portal blood vessels. Tyrosine hydroxylase/NPY immunoreactive nerve terminals from sympathetic ganglia innervate blood vessels and both submucous and myenteric ganglia. DYN/VIP/cholecystokinin neurons in the nerve plexus send axon collaterals to the inferior mesenteric ganglia and form a feedback loop. Substance P (SP) and calcitonin gene related peptide may exist in sensory nerve terminals. SP neurons in the myenteric ganglia innervate smooth muscles. SOM neurons inhibitory interneurons in the ganglia. SIF cells act as secretory paraneurons, the effect being long-lasting and nonspecific, while sympathetic neurons innervate both nerve plexus and intestinal tissues, and the effects in this case are specific, fast and of short duration.

Animals↗
PubMed1989

[Effects of experimental compression of the brainstem on the circulatory and the respiratory parameters in the rabbit].

Circulatory and respiratory changes following a mechanical compression of the brainstem of the rabbit were studied. Under light ether anesthesia, the animal was tracheostomized, immobilized by pancuronium bromide, and mechanically ventilated, following which the skull was fixed and suboccipital craniotomy was performed, and finally the brainstem was exposed. The site of compression was selected as (A): 3mm lateral, 3mm rostral, (B): 2mm lateral and (C): 3mm lateral, 3mm caudal, of the obex, respectively. After inhalation of ether was discontinued and elimination of the effect of muscle relaxant was confirmed, the direct compression with glass stick of 0.8mm in diameter was carried out. In each point, vertical compression of 1mm, 2mm and 3mm, was performed stereotaxically. In each depth of the compression, 3 to 4 animals were studied. The blood pressure was measured directly in the femoral artery and the respiratory changes by impedance pneumography. The circulatory changes, biphasic change of arterial pressure and/or transient bradycardia occurred earlier than the respiratory changes in 2mm and 3mm depth of the compression in all 3 points. CO2 response curve with rebreathing method was obtained before and 15 minutes after the compression to evaluate the degree of damage of the medullary respiratory center. The depression of CO2 response curve was observed only in 3mm compression depth at the point (A). It is concluded from this study that excessive invasion of the brainstem during the suboccipital craniotomy under controlled ventilation could be detected through the observation of the changes in circulatory parameters.

Animals↗
PubMed1988

Projection pathways, co-existence of peptides and synaptic organization of nerve fibers in the inferior mesenteric ganglion of the guinea-pig.

The presence of immunoreactive enkephalin, dynorphin, vasoactive intestinal polypeptide, cholecystokinin, substance P and neuropeptide Y in nerve fibers that project to the guinea-pig inferior mesenteric ganglion was analysed, after different denervation and ligation procedures. A quantitative analysis demonstrates that enkephalin- and substance P fibers reach the ganglion mainly via lumbar splanchnic and partly via intermesenteric nerves. Dynorphin-, vasoactive intestinal polypeptide- and cholecystokinin fibers reach the ganglion mainly via colonic and partly via hypogastric or intermesenteric nerves. Neuropeptide Y fibers enter via intermesenteric, lumbar splanchnic and hypogastric nerves and pass through the ganglion. Analysis of serial 0.5 micron sections tends to confirm co-existence: of dynorphin, vasoactive intestinal polypeptide and cholecystokinin in fibers projecting from the colon; of dynorphin with substance P in the lumbar splanchnic nerves; and of neuropeptide Y with substance P in the hypogastric and colonic fibers. Synaptic contacts, predominantly axodendritic, onto the ganglion cells from enkephalin-, vasoactive intestinal polypeptide-, and substance P-containing terminals were revealed by electron microscopy. Enkephalin-immunoreactive axon varicosities are filled with small, clear vesicles with a few large, cored vesicles and form asymmetric synapses; dynorphin-, vasoactive intestinal polypeptide- and cholecystokinin-immunoreactive axon varicosities are rich in large, dense-cored vesicles and form symmetric synapses.

Animals↗
PubMed1988

Effects of endogenous and exogenous parathyroid hormone on tubular reabsorption of calcium in pseudohypoparathyroidism.

Resistance to the proximal tubular actions of PTH is a well defined feature in patients with pseudohypoparathyroidism type I (PsH). However, it is less clear whether there also is resistance to the distal tubular effect of PTH on calcium reabsorption in these patients. Thus, we examined the effects of endogenous and exogenous PTH on calcium reabsorption in seven patients with PsH before and during treatment with 1 alpha-hydroxyvitamin D3 (1 alpha OHD3). Eleven patients with idiopathic hypoparathyroidism served as controls. Before treatment, urinary calcium excretion was comparable in the two groups and did not decrease significantly after PTH infusion in either group. During treatment with 1 alpha OHD3, in contrast, steady state urinary calcium excretion in patients with PsH was much lower than that in patients with idiopathic hypoparathyroidism at comparable serum calcium concentrations and did not exceed the upper limit of the normal range when PsH patients were normocalcemic. Infusion of PTH into 1 alpha OHD3-treated PsH patients led to a significant reduction in urinary calcium excretion, even though PTH had no effect on their urinary cAMP or phosphate excretion. These findings suggest that the renal resistance to PTH in patients with PsH is confined to its proximal tubular actions and does not include its distal tubular effect on calcium reabsorption, at least during treatment with active vitamin D metabolites.

Adolescent↗
PubMed1988

Effect of neutrophil activating substances on intracellular generation of phagocyte chemiluminescence by means of luminol-bound microspheres.

The intracellular chemiluminescence of granulocytes was measured by luminol-bound microspheres. After one minute of incubation, which was necessary for the granulocytes to phagocytize microspheres, intracellular chemiluminescence was generated. The intracellular chemiluminescence was enhanced by the introduction of granulocyte stimuli including concanavalin A, phorbol-myristate acetate, and formyl peptides. This incremental effect was the result of certain metabolic changes inside the cells. This newly discovered chemiluminescent reagent promises to be a useful tool for examining metabolic changes inside phagocytic cells.

Concanavalin A↗
PubMed1987

Small vesicle bouton synapses on the distal half of the lateral dendrite of the goldfish Mauthner cell: freeze-fracture and thin section study.

To understand principles of synaptic integration, it is necessary to define the types of synapses on a particular neuron and their distribution. Thin sectioning and double replica freeze-fracture techniques were employed to characterize the small vesicle bouton (SVB) synapses on the distal half of the Mauthner (M) cell lateral dendrite, which probably mediate a remote dendritic inhibition. Three morphologically distinct SVB synapses, types A, B, and C, were found. These three SVB synapses form roughly 90% of the synapses on the distal half of the lateral dendrite, with types A and B being most common. The SVB A synapse is characterized by mostly oval and round synaptic vesicles, a discrete presynaptic active zone with a highly variable shape, and a postsynaptic active zone with no apparent particle aggregate in either the E or P face. At the SVB B synapse, most of the synaptic vesicles are flat. A very high particle density is present throughout the presynaptic P face, and vesicle attachment sites are dispersed over much of the presynaptic membrane. Postsynaptic P face particle aggregates are subjacent to the presynaptic vesicle attachment sites, and are often large and anastomosing. The SVB C synapse is characterized by synaptic vesicle profiles that vary from flattened to round. The SVB C cytoplasm was unclouded by the flocculent material that characterized SVBs A and B. The presynaptic active zones at the SVB C synapse are discrete, and macular or oblong. No particle aggregates are apparent in the postsynaptic active zone. Small, macular particle aggregates were found in nonactive zone regions of the postsynaptic E face of all three types of SVBs. Small subsurface cisterns were also observed underlying the M cell membrane at all three types of SVB synapses. Neither the postsynaptic E face aggregates nor the subsurface cisterns were ever observed directly subjacent to presynaptic active zones, but were often seen adjacent to active zones. Short, straight rows of particles and short cylinders were often seen in both pre- and postsynaptic surrounding zone regions of SVB A and C synapses. These structures are thought to represent tight junctions.

Animals↗
PubMed1987

Synaptic structure of the monoamine and peptide nerve terminals in the intermediolateral nucleus of the guinea pig thoracic spinal cord.

Synaptic organization of the intermediolateral nucleus of the guinea pig thoracic spinal cord was examined with particular focus on monoamine- and peptide-containing nerve terminals. Axon varicosities having flat synaptic vesicles constituted 17% of all axons in the nucleus and formed exclusively symmetric synapses. Enkephalin-, substance P-, somatostatin-, 5-hydroxytryptamine-, and catecholamine-immunoreactive nerve terminals were densely distributed, while neurotensin, vasoactive intestinal polypeptide-, oxytocin-, and cholecystokinin-8-immunoreactive nerves were sparse in the nucleus. Coexistence of 5-hydroxytryptamine and enkephalin was demonstrated, and coexistence of somatostatin and enkephalin as well as somatostatin and 5-hydroxytryptamine in the same axons was also shown by serial semithin sections. Catecholamine axons labelled by 5-hydroxydopamine formed axodendritic and axosomatic synapses and made direct synaptic contacts on the preganglionic sympathetic neurons identified by retrograde transport of horseradish peroxidase. Direct synaptic contacts from enkephalin- and substance P-immunoreactive axons to preganglionic sympathetic neurons were also revealed. Enkephalin-, substance P-, and 5-hydroxytryptamine-immunoreactive axons formed axodendritic and axosomatic synapses. Catecholamine axon varicosities constituted 19% of all axon varicosities in the nucleus and 30% of them showed synaptic specializations in a sectional plane. Axon varicosities immunoreactive to enkephalin, 5-hydroxytryptamine, and substance P constituted approximately 35, 19, and 13% of all axon varicosities, respectively, while those with synaptic contacts made up 27, 30, and 26%, respectively, in a sectional plane. Enkephalin-, 5-hydroxytryptamine-, and noradrenaline-immunoreactive axons showed mainly symmetric synaptic contacts.

Animals↗
PubMed1987

Myogenesis in vitro as seen with the scanning electron microscope.

In this paper, we review our recent observations by scanning electron microscopy (SEM) on the differentiation of the cell surface and cytoplasmic organelles in embryonic chick skeletal muscle cells in vitro. The changes of the surface structures of myoblasts during mitosis were essentially similar to those of other cell types, but the characteristic spindle shape of myoblasts did not change throughout most of this period. Cytoskeletal structures under the sarcolemma were examined by Triton extraction and metal coating. Cells in S, G2 and M possessed a dense, and those in G1 a loose filament network under the membrane. Myotubes possessed a dense network under the sarcolemma. In the fusion area between a myoblast and a myotube, the cytoskeletal domain of the former could be distinguished from the latter because of the mosaic appearance of the subsarcolemmal cytoskeletal network. This network was composed predominantly of 10-13 nm filaments; they were identified as actin filaments because of their decoration with myosin subfragment-1. Triton treatment and thiocarbohydrazide-osmium staining allowed us to visualize myofibrils. They ran in the direction of inferred stress lines brought about by elongation and adhesion of the cells to substrate. Intracellular membranous organelles could be seen by the freeze-polishing and osmium-maceration procedure. Mitochondria exhibited complex irregular branchings. T system tubules ran a tortuous course. Sarcoplasmic reticula with occasional dilatations were connected to each other. The results are of sufficient promise to encourage more extensive analysis of myogenesis by SEM.

Animals↗
PubMed1986

Direct synaptic contacts of catecholamine axons on the preganglionic sympathetic neurons in the rat thoracic spinal cord.

Preganglionic sympathetic neurons were labelled by retrograde transport of horseradish peroxidase, while catecholamine axon varicosities were marked by the uptake of 5-hydroxydopamine in the intermediolateral nucleus of the rat. The direct synaptic contacts from the catecholamine axons to the preganglionic sympathetic neurons were demonstrated. Catecholamine axons formed symmetric synapses.

Adrenergic Fibers↗