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Biomedical subjects

M Tohyama

Publications and source records attributed to M Tohyama.

At least 433 records · Page 24Linked to original sources
PubMed1986

Transplants in the peri- and intraventricular region grow better than those in the central parenchyma of the caudate.

The correlation between the growth of transplanted cells and behavior recovery in rats with lesions in the unilateral nigrostriatal dopamine (DA) pathway was investigated. Grafted cells in the lateral or third ventricle grew better than those in the caudate parenchyma. Immunocytochemical staining of tyrosine hydroxylase (TH) revealed that axons or dendrites of TH-like immunoreactive (TH-LI) cells transplanted periventricularly extended and ramified better than those of cells implanted in the central parenchyma of the caudate nucleus. The extent of ramification was well correlated with the recovery of behavioral imbalance. Data suggest that the growth and ramification of transplanted TH-LI cells are the most critical factors affecting behavior recovery, and this growth depends on the transplantation sites.

Animals↗
PubMed1986

The formation of new neuronal circuit between transplanted nigral dopamine neurons and non-immunoreactive axon terminals in the host rat caudate nucleus.

Using immunoelectron microscopic techniques, whether or not host neuronal elements newly form synaptic contact with the grafted dopamine (DA) neurons in the caudate nucleus of the rat with unilateral lesion in the nigrostriatal DA pathway was examined. Tyrosine hydroxylase (TH) was used as a marker for DA-containing structures. Motor imbalances after the lesion and before or after the transplantation were assessed by the amount of circlings after the injection of Met-amphetamine. In animals which recovered well from motor imbalance, non-immunoreactive axon terminals made synaptic contact with grafted TH-positive cell bodies and their dendrites. Since the incidence of these synapses was quite low in poorly recovered animals, the formation of a new neuronal circuit may be one of the important bases for behavior recovery.

Animals↗
PubMed1986

An immunohistochemical study on the river lamprey retina.

The localization of structures immunoreactive to various polypeptides and proteins in the retina of the river lamprey (Lampetra japonica) was investigated by means of an indirect immunohistofluorescence method. In the majority of frozen sections, a subpopulation of amacrine cells showed the immunoreactivity (IR) to one of the examined antisera against corticotropin-releasing factor, glucagon, neuropeptide Y, somatostatin, visinin and 5-hydroxytryptamine, respectively. A few fibers in the inner plexiform layer were immunoreactive to cholecystokinin or substance P antiserum. The visinin-like IR was also found in two types of bipolar cells. The IR was positive in Müller cells against glutamine synthetase but not to glial fibrillary acidic protein. In some flat-mounted preparations, glucagon- and serotonin-like reactive amacrine cells and visinin-like immunoreactive bipolar cells (distally located) could be observed. The results obtained suggest that in the lamprey retina the cytoplasmic property of some cells is similar to, but that of others is different from, vertebrate retinal cells.

Animals↗
PubMed1986

Immunohistochemical demonstration of histamine N-methyltransferase-like structures in rat kidney.

Histamine N-methyltransferase (S-adenosylmethionine: histamine N-methyltransferase, E.C. 2.1.1.8) was purified to homogeneity from rat kidney, and antibody was raised against it in guinea pigs. The antibody immunoprecipitated histamine N-methyltransferase. Immunofluorescent histochemical studies with anti-histamine N-methyltransferase antibody as the first antibody and goat anti-guinea pig IgG conjugated with fluorescein isothiocyanate as the second, showed the presence of immunoreactive structures in the proximal tubules of rat kidney. The brain showed no immunoreaction with the antibody.

Animals↗
PubMed1986

Distribution of calcitonin gene-related peptide-containing fibers in the urinary bladder of the rat and their origin.

By use of indirect immunofluorescence, this study demonstrated the presence of calcitonin gene-related peptide-like immunoreactive (CGRPI) fibers in the bladder of the rat. These fibers were abundant in the muscle layer, in which they ran parallel to the muscles, submucosa, and epithelium. No immunoreactive cells were detected. We also examined the origins of these fibers, using a method that combined biotinized retrograde tracer (biotin-wheat germ agglutinin) (B-WGA) and immunocytochemistry. Injection of the tracer into the bladder resulted in the demonstration of small to medium-sized labeled cells that contain CGRPI structures in single dorsal root ganglion cells mostly at the level of L6 and S1, but also a few at L2. Double-staining for CGRPI and immunoreactive P-like substance (SPI) indicated that there are cells in the dorsal root ganglia at the level of L6 and S1 that react to both, but that there are many CGRPI-positive cells that contain no demonstrable SPI; most of the latter are large.

Animals↗
PubMed1986

The presence of a calcitonin gene-related peptide in the olivocochlear bundle in rat.

The origins of calcitonin gene-related peptide immunoreactive (CGRPI) fibers in the cochlea were examined in rats. Parasagittal transection of the brain just medial to the principal sensory trigeminal nucleus resulted in the ipsilateral disappearance of CGRPI fibers in the cochlea, indicating that the origins of these fibers lie in the central nervous system. Next, we used a highly sensitive method combining retrograde tracing and immunohistochemistry to identify the origins of the CGRPI fibers in the cochlea. After injection of biotin-wheat germ agglutinin (b-WGA) into the cochlea, CGRPI neurons in the ipsilateral lateral superior olivary nucleus also contained b-WGA granules. These findings indicated that CGRPI efferent fibers are major components of the olivocochlear bundle.

Animals↗
PubMed1986

Sensitive double-labeling technique of retrograde biotinized tracer (biotin-WGA) and immunocytochemistry: light and electron microscopic analysis.

We developed a simple method to identify fiber projections that contain bioactive substances using biotinized wheat-germ agglutinin. Tracer that accumulated retrogradely in the soma was made visible under the light microscope by linking it with streptavidin-Texas red, which has a red fluorescence, while antigen was demonstrated in the same section by indirect immunofluorescence using fluorescein isothiocyanate with green fluorescence as a marker. Under the electron microscope, the tracer was identified using streptavidin-colloidal gold particles, while the antigen was demonstrated in the same ultrathin section using the peroxidase-antiperoxidase technique. This method makes it possible to demonstrate the locations of both the biotinized retrograde tracer and the antigen in the soma of the same neuron at both light and electron microscopic levels.

Animals↗
PubMed1986

Ontogeny of gamma-melanocyte-stimulating hormone in the brain and hypophysis of the rat: an immunohistochemical analysis.

The ontogeny of gamma-melanocyte stimulating hormone (gamma-MSH)-like immunoreactive (gamma-MSHI) structures in the brain and hypophysis was investigated in the rat by means of indirect immunofluorescence. gamma-MSHI neurons in the arcuate nucleus appeared at Day 13 of gestation, in the anterior hypophysis at Day 16, in the intermediate lobe at Day 18, and in the nucleus commissuralis after birth. gamma-MSHI fibers first appeared at Day 15 of gestation in the hypothalamic area and extended dorsally to reach the surface of the diencephalon. At Day 16 of gestation, another gamma-MSHI fiber bundle was found that ran laterally along the ventral surface of the diencephalon. At Day 19, immunoreactive fibers first appeared in the forebrain, diencephalon, midbrain and upper pons, and thereafter they increased in number, reaching a maximum at postnatal Day 15. gamma-MSHI fibers in the lower pons and medulla oblongata first appeared after birth. They also increased in number with age and reached a maximum at postnatal Day 15. The present ontogenetical study has demonstrated the different times of first appearance of each of the 3 major gamma-MSHI structures-containing cell groups in the brain, i.e., the arcuate nucleus, hypophysis and nucleus commissuralis. These findings may reflect the different functions of 3 groups of cells.

Animals↗
PubMed1986

Cloning and characterization of a cDNA specific for bovine retina.

A retina-specific cDNA clone (pCR18) was selected from a bovine retinal cDNA library and characterized. The clone pCR18 consisted of 905 base pairs and hybridized to the mRNA of about 12S from the bovine retina, but not that from the brain or liver. The nucleotide sequence revealed a long open reading frame which encodes a 147 amino acid polypeptide of about 15,700 Da. No significant sequence homology with the predicted protein was found in the protein sequence library of about 3500. Messenger RNA which hybridized to pCR18 translated a polypeptide of about 19,000 Da in a reticulocyte translation system. Southern blot analysis indicated that the bovine genome contains a single copy of this gene. Furthermore, RNA dot analysis showed that the poly(A)+ RNA from the human retinoblastoma cell lines (Y79 and WERI) hybridized to pCR18, whose intensity was comparable to that of the bovine retina. In situ hybridization revealed that pCR18 was expressed mostly in some ganglion cells of the rat retina. The results suggest that cDNA clone (pCR18) encodes a protein specific for the retina and mRNA for pCR18 is mostly localized in the retinal ganglion cells and also expressed in the human retinoblastoma cells, although its function remains to be elucidated.

Animals↗
PubMed1986

A substance P-containing pathway from the hypothalamic ventromedial nucleus to the medial preoptic area of the rat: an immunohistochemical analysis.

The destruction of the hypothalamic ventromedial nucleus, which contains a group of substance P-like immunoreactive neurons, resulted in a marked ipsilateral reduction of these fibers in the medial preoptic area. To test if and to what extent the substance P-like immunoreactive neurons in the ventromedial nucleus project to the medial preoptic area, we applied a sensitive double-labeling method capable of detecting substance P-like immunoreactivity in neurons retrogradely labeled with biotin-wheat germ agglutinin following injection of the tracer in the medial preoptic area. The appearance of many double-labeled cells in the hypothalamic ventromedial nucleus provides strong evidence for the existence of a prominent substance P containing pathway from the ventromedial nucleus to the medial preoptic area. A few doubled-labeled cells were also seen in the lateral hypothalamus, which therefore seems to be an additional source of substance P-like immunoreactive fibers in the medial preoptic area.

Animals↗
PubMed1986

Enkephalin-like immunoreactive neurons and fibers in the ventromedial hypothalamic nucleus.

Enkephalin-like immunoreactive (ENK-IR) neurons and fibers in the rat ventromedial hypothalamic nucleus (VMH) were examined by light and electron microscopy using the peroxidase-antiperoxidase immunocytochemistry. There were groups of ENK-IR neurons present in the ventrolateral part of the VMH, and such neurons were scattered elsewhere. These neurons had perikarya 10-25 microns in diameter with moderately developed cell organelles and enfolded nuclei that were often distributed eccentrically placed in the cell. The perikarya and dendrites contained diffuse, large-cored vesicles (LCV) (60-230 nm with a predominance in the 60-80 nm). ENK-IR neurons received synaptic inputs on the soma and dendrites from unlabeled axonal boutons containing many small, clear vesicles and occasional LCV. The ultrastructural features of the ENK-IR cells in the VMH seemed to correspond to the "common cells" described by Millhouse. Dense ENK-IR fibers were distributed in this nucleus throughout the rostrocaudal and ventrodorsal areas. Axonal boutons containing numerous small, clear vesicles, and dispersed LCV generally made synaptic contacts with the cell bodies and dendrites of unlabeled neurons. The findings suggest that opioid peptides directly influence VMH neurons through synaptic contacts.

Animals↗
PubMed1986

Ontogeny of substance P-containing structures in the chicken retina: immunohistochemical analysis.

We examined the ontogeny of the system with substance P-like immunoreactivity (SPI) in the chicken retina by indirect immunofluorescence method. Amacrine cells containing SPI first appeared at embryonic day 7 (E7) in the peripheral portion of the retina. At E8, they had increased in number and now extended medially to the central portion. They continued to increase in number, reaching a maximum between E13-15. After the chicks hatched, the number of SPI cells was unchanged. SPI fibers first appeared at E8 in the periphery. SPI fibers were both at the ora serrata and in the inner plexiform layer (IPL), which were not abundant. After E8, they increased in number. The increase was particularly rapid in the IPL between E10 and E16 and at the ora serrata between E15 and E19. SPI fibers reached the maximum number immediately after hatching. After that, SPI fibers in the IPL were unchanged in number. Those at the ora serrata decreased slightly in number with age, though SPI fibers were still numerous in the chicken retina 2 weeks and 1 month after hatching. These results showed that development of SPI is different for subtypes of SPI cells and for different location. This heterogeneity in development may reflect the functional differences of substance P depending on cell type and fiber location.

Animals↗
PubMed1986

Space variances in the mean-square pressure at the boundaries of a rectangular reverberation room.

It was found that it was possible to reduce the number of samples needed for power measurements by sampling at the boundaries in a reverberation room. The space variances in the mean-square pressure of oblique wave fields in a rectangular reverberation room were calculated. The sound source was assumed to be a narrow-band noise source. Space variances throughout the room sigma 2A, on the floor sigma 2B, on the edge sigma 2C, and at the corner sigma 2G were compared with each other numerically. The numerical results confirmed that the relation sigma 2G less than sigma 2C less than sigma 2B less than sigma 2A holds well. Particularly, in a rectangular reverberation room, under the condition that the receiver position is fixed at the corner of the room (corner method), the number of samples reduces to 1/2-1/3 the number of samples needed under the condition that both receiver positions and source positions are changed throughout the room. Some experimental results regarding the power measurements by the corner method are also shown. The experimental results confirmed the suitable estimation of the power for a noise source at low frequencies.

Acoustics↗
PubMed1986

Effect of calcitonin gene-related peptide on the cyclic AMP level of isolated mouse diaphragm.

The effect of calcitonin gene-related peptide (CGRP) on the cyclic nucleotide level in isolated mouse diaphragm was investigated. CGRP at concentrations of up to 1 microM caused dose-dependent increases in cyclic AMP levels but had no effect on cyclic GMP levels. At 1 microM, CGRP increased cyclic AMP levels by about 2.7-fold. Moreover, in the presence of phosphodiesterase inhibitor (Ro 20-1724), CGRP still caused even greater dose-dependent increases in cyclic AMP levels. Even in the presence of propranolol, a beta-adrenergic antagonist, CGRP stimulated increased cyclic AMP levels. In addition, specific binding of CGRP was observed in mouse diaphragm. All these results suggest that CGRP increases intracellular cyclic AMP levels via a CGRP receptor but not the beta-adrenergic receptor.

Animals↗
PubMed1985

Coexistence of pancreatic polypeptide and substance P in the chicken retina.

The present immunohistochemical study using flat-mounted and frozen sections has revealed that in the chicken retina, pancreatic polypeptide (PP)-, such as avian pancreatic polypeptide (APP) and neuropeptide Y (NPY), and substance P (SP)-like immunoreactive (PPI and SPI) amacrine cells are composed of more heterogeneous subpopulations than has hitherto been supposed. Furthermore, using double-staining immunohistochemical procedures, we demonstrate that a substantial proportion of some subtypes of PPI cells contain SPI and that the ratio of both PPI and SPI cells to total immunoreactive cells differs according to the retinal portions and cell types.

Animals↗