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K Hama

Publications and source records attributed to K Hama.

At least 55 records · Page 3Linked to original sources
PubMed1989

[Establishment of clinically healthy gingiva in Macaca irus].

UNLABELLED: The purpose of this study was to assess the methods of establishing of clinically (experimental) healthy gingiva and to evaluate the status of healthy gingiva in Macaca irus. Three monkeys (2 males and 1 female) were used. After preliminary feeding with hard food for 6 months, plaque control procedures (scrubbing method, modified Stillman method, and flossing) were started. Frequency of plaque removal was three times per week under KETALAR (SANKYO, Co. Tokyo), dissociative anesthesia. We also monitored clinical data. RESULTS: 1. Forty-nine days later, clinically healthy gingiva were achieved. During this period, no side effects and no tolerance occurred using 12.5 mg/kg of KETALAR, and effective time to perform the procedure was 21.8 minutes. 2. Depending on the plaque control procedure, plaque index (P11), gingival index (GI), and probing depth (PD) were reduced (especially in the first week). However, the level of marginal gingiva (LMG) did not change. 3. Initially and throughout the experiment, PII, GI, PD were lower value in lower jaws, but by the end of experiment there were no differences between the two jaws in PII and PD. However, GI was still lower in the lower jaw at this time. There were no differences between the data for the right and left sides of the jaws at any time throughout the experiment. 4. At the end of experiment, the clinically (experimental) healthy gingiva yielded the following data: PII, 1.7 +/- 0.61; GI, 0.1 +/- 0.60; PD, 1.3 +/- 0.53. No individual differences were found in any of the monkeys at the end of experiment.

Animals↗
PubMed1988

Possible coexistence of amino acid (gamma-aminobutyric acid), amine (dopamine) and peptide (substance P); neurons containing immunoreactivities for glutamic acid decarboxylase, tyrosine hydroxylase and substance P in the hamster main olfactory bulb.

The coexistence of immunoreactivities for glutamic acid decarboxylase (GAD), tyrosine hydroxylase (TH) and substance P (SP) was revealed in the hamster main olfactory bulb, using the peroxidase-antiperoxidase immunohistochemical method. Adjacent 40 micron thick Vibratome sections were incubated in different antisera and those cells which were bisected by the plane of sectioning were identified at the paired surfaces of two consecutive sections. The coexistence of the immunoreactivities for 1) TH and GAD, 2) TH and SP and 3) GAD and SP in the same cells could thus be determined by observing the immunoreactivity of the two halves of the cell incubated in two different antisera. About 70% of TH-like immunoreactive (TH-LI) neurons in the periglomerular region also contained GAD-like immunoreactivity, whereas about 45% of GAD-LI ones were also TH-like immunoreactive. Furthermore, almost all (more than 95%) of SP-LI neurons contained both GAD-like and TH-like immunoreactivities. These observations indicate that in the periglomerular region of the hamster main olfactory bulb, some neurons (about 9% of all neurons containing TH-like and/or GAD-like immunoreactivities) may contain three different categories of neuroactive substances, that is, amino acid (GABA), amine (dopamine) and peptide (SP).

Animals↗
PubMed1988

Immunocytochemical study of GABAergic neurons containing the calcium-binding protein parvalbumin in the rat hippocampus.

The structural features of PV-immunoreactive (PV-I) neurons, a particular subpopulation of GABAergic neurons, in the hippocampus were studied by immunocytochemistry. The PV-I cell bodies were concentrated within the stratum pyramidale (SP) and stratum oriens (SO) in the hippocampus. PV-I puncta were frequent in SP, while they were rarely seen in other layers. The dendritic arborization of PV-I neurons resembled that of some of the nonpyramidal cells observed after Golgi-impregnation. The most commonly observed PV-I neurons had their perikarya located in SP with dendrites extending into SO and the stratum radiatum (SR). Most of the dendrites in SR had typical beaded or varicose segments. The dendrites extending into SO had few beaded parts. There were many bipolar and multipolar neurons with smooth dendrites in SO, but only a small number of such multipolar neurons in SR. An electron microscopic analysis revealed that PV-I products were located to perikarya, dendrites, myelinated axons and synaptic boutons. The perikarya of PV-I neurons exhibited several ultrastructural features of nonpyramidal cells, e.g., abundant cisternae of endoplasmic reticulum, mitochondria and other perikaryal organelles, an infolded nuclear envelope and intranuclear inclusions. They received many asymmetric synapses with round presynaptic vesicles. There were numerous PV-I boutons, presumably axonal endings, covering the pyramidal cell bodies. The PV-I boutons also contacted the axon initial segments and proximal dendrites of the pyramidal cells. In addition PV-I terminals were found on somata and dendrites of both PV-I or PV-negative nonpyramidal cells. The results suggest that PV-containing neurons include basket and axo-axonic cells.

Animals↗
PubMed1988

Gap junctions on GABAergic neurons containing the calcium-binding protein parvalbumin in the rat hippocampus (CA1 region).

Gap junctions were identified for the first time on chemically defined neurons in the central nervous system. Gap junctions were thus demonstrated on GABAergic neurons containing the calcium-binding on GABAergic neurons containing the calcium-binding protein parvalbumin (PV) in the rat hippocampus. Thin and semithin (0.5 micron thick) sections were cut alternately and consecutively from osmium-fixed tissue which was embedded in epoxy resin and usable for conventional electron microscopic studies. The semithin sections were processed for postembedding immunocytochemistry using an anti-PV serum. Structures corresponding to the PV-immunoreactive (PV-I) profiles on the semithin sections were easily identified on electron micrographs from the adjacent thin sections. Using this technique gap junctions were found (1) between PV-I dendrites, (2) between PV-I dendrites and PV-I somata and (3) between PV-I dendrites and small processes whose origin could not be identified. Despite a systematic search, we did not find gap junction between PV-negative processes.

Animals↗
PubMed1988

Physiological heterogeneity of nonpyramidal cells in rat hippocampal CA1 region.

Functional differentiation of nonpyramidal cells was studied by intracellular recording and staining of cells located in the stratum pyramidale or along the border between the stratum radiatum and the stratum lacunosum-moleculare of slices prepared from rat hippocampal CA1 region. In the stratum pyramidale, nonpyramidal cells (fast-spiking cells, type I cells) exhibited brief-duration action potentials (mean spike-width at one-half amplitude = 0.28 ms, N = 9) and little or no frequency adaptation of spike discharge to depolarizing current pulse. These cells ramified axon collaterals mainly in the stratum pyramidale or in the apical side of the stratum oriens. The HRP-injected nonpyramidal cells located between the stratum radiatum and the stratum lacunosum-moleculare (type II cells) showed different physiological characteristics from fast-spiking cells in the stratum pyramidale. The spike width was longer than that of fast-spiking cells (mean duration measured at one-half amplitude = 0.61 ms, N = 11) and these cells exhibited adaptation of spike discharge in response to depolarizing current pulses. Following hyperpolarizing current pulses, a depolarizing potential was produced in some type II cells. Although most cells of this group sent axon collaterals into the stratum radiatum or into the stratum lacunosum-moleculare, there were also cells whose axon collaterals extended to and ramified in the stratum pyramidale. In contrast to pyramidal cells, spikes of both types of nonpyramidal cells did not broaden during repetitive firing evoked by large depolarizing current pulses. Stimulation of the stratum radiatum caused excitatory and inhibitory postsynaptic potentials in both type I and II cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1988

Application of a human T cell line derived from a Sézary syndrome patient for human interleukin 4 assay.

Interleukin 4 (IL-4) is a multi-functional biological regulator molecule. We developed a simple assay system for human IL-4, using a IL-2-dependent T cell line designated Sez 627 cell line. Sez 627 cells were found to respond only to human IL-4 and human IL-2, but not to other available lymphokines. In combination with mouse IL-2-dependent CTLL-2 cell line, which responds to both human and murine IL-2 but not to human IL-4, human IL-4 activity can be discriminated from human IL-2 activity.

Biological Assay↗
PubMed1987

GABAergic neurons containing the Ca2+-binding protein parvalbumin in the rat hippocampus and dentate gyrus.

The distribution of Ca2+-binding protein, parvalbumin (PV), containing neurons and their colocalization with glutamic acid decarboxylase (GAD) were studied in the rat hippocampus and dentate gyrus using immunohistochemistry. PV immunoreactive (PV-I) perikarya were concentrated in the granule cell layer and hilus in the dentate gyrus and in the stratum pyramidale and stratum oriens in the CA3 and CA1 regions of the hippocampus. They were rare in the molecular layer of the dentate gyrus, in the stratum radiatum and in the stratum lacunosum-moleculare of the hippocampus. PV-I axon terminals were restricted to the granule cell layer, the stratum pyramidale and the immediately adjoining zones of these layers. Almost all PV-I neurons were also GAD immunoreactive (GAD-I), whereas only about 20% of GAD-I neurons also contained PV. The percentages of GAD-I neurons which were also immunoreactive for PV were dependent on the layer in which they were found; i.e. 40-50% in the stratum pyramidale, 20-30% in the dentate granule cell layer and in the stratum oriens of the CA3 and CA1 regions, 15-20% in the hilus and in the stratum lucidum of CA3 region and only 1-4% in the dentate molecular layer and in the stratum radiatum and the stratum lacunosum-moleculare of the CA3 and CA1 regions. PV-I neurons are a particular subpopulation of GABAergic neurons in the hippocampal formation. Based on their morphology and laminar distribution, they probably include basket cells and axo-axonic cells.

Animals↗
PubMed1987

Differential effect of functional olfactory deprivation on the GABAergic and catecholaminergic traits in the rat main olfactory bulb.

The effects of the unilateral olfactory naris closure were studied immunohistochemically in the main olfactory bulb of adult rats. In the olfactory deprived bulbs, the tyrosine hydroxylase-immunoreactive elements in the glomeruli and the juxtaglomerular region decreased drastically, whereas the glutamate decarboxylase-immunoreactive elements in these regions showed no appreciable changes, indicating the differential effects of olfactory deprivation on catecholaminergic and GABAergic traits in spite of their coexistence in some neurons in these regions.

Animals↗
PubMed1987

An aspect of the organization of the GABAergic system in the rat main olfactory bulb: laminar distribution of immunohistochemically defined subpopulations of GABAergic neurons.

The organization of the GABAergic system in the rat main olfactory bulb was investigated immunohistochemically using antisera against glutamic acid decarboxylase (GAD), tyrosine hydroxylase (TH), parvalbumin (PV) and methionin-enkephalin-Arg6-Gly7-Leu8 (ENK). Some GABAergic neurons were shown to contain TH immunoreactivity in the glomerular layer, PV immunoreactivity in the external plexiform layer and ENK-like immunoreactivity in the granule cell layer, indicating the stratified organization of the GABAergic subsystems.

Animals↗
PubMed1987

Two subtypes of non-pyramidal cells in rat hippocampal formation identified by intracellular recording and HRP injection.

Intracellular recording and injection of horseradish peroxidase in rat hippocampal slice preparations revealed the existence of two physiologically distinct types of non-pyramidal cells: one a fast spiking type and the other a non-fast spiking type. In the CAl pyramidal cell layer and the subgranular zone of the dentate gyrus fast spiking cells were found, while in the border area between the stratum lacunosum-moleculare and the stratum radiatum, non-fast spiking cells were found exclusively. These two types of non-pyramidal cells may play different roles in the functions of hippocampal neuronal networks.

Action Potentials↗
PubMed1987

An aspect of the organizational principle of the gamma-aminobutyric acidergic system in the cerebral cortex.

The possibility of the colocalization of a Ca2+-binding protein, parvalbumin (PV), with peptides, cholecystokinin (CCK) and somatostatin (SS), all of which are known to be contained gamma-aminobutyric acidergic neurons in the cerebral cortex, was tested in the rat visual cortex by means of immunohistochemistry using the adjacent section technique. No PV immunoreactive (PV-I) neurons showed CCK-like immunoreactivity, and almost none (932 out of 934 PV-I neurons examined) showed SS-like immunoreactivity. These observations suggest that the GABAergic system of the cerebral cortex may consist of some distinct subsystems with different chemical and presumably physiological characteristics.

Animals↗
PubMed1987

Postnatal development of neurons containing both catecholaminergic and GABAergic traits in the rat main olfactory bulb.

Postnatal development of catecholaminergic and gamma-aminobutyric acid (GABA)-ergic neurons in the periglomerular region of the rat main olfactory bulb was studied immunohistochemically using antisera against tyrosine hydroxylase (TH), glutamic acid decarboxylase and GABA. TH-like immunoreactive neurons almost always contained GABA-like immunoreactivity in the first postnatal week, but about 10% of them did not contain GABA-like immunoreactivity in older animals.

Aging↗
PubMed1987

Interleukin 4 (IgG1 induction factor): a multifunctional lymphokine acting also on T cells.

A cDNA encoding the murine interleukin 4 (IL4) (IgG1 induction factor/B cell-stimulating factor no. 1) was recently cloned (Noma et al., Nature 1986.319: 640; Lee et al., Proc. Natl. Acad. Sci. USA 1986. 83: 2061). In this report we tested recombinant IL 4 in various T cell assays. It was found that IL 4 activated the murine T cell line CTLL to increased DNA synthesis but not to growth. It also activated normal concanavalin A (Con A)-stimulated T cells both to increased DNA synthesis and to growth. These T cell growth factor-like activities were not inhibitable by anti-IL 2 receptor antibodies. Evidence is given that both Lyt-2+ and L3T4+ T cells responded to IL 4. Finally, IL 4 acted synergistically with phytohemagglutinin or Con A on normal T lymphocytes as well as on thymocytes. These data, as well as those of others, imply that lymphokines have a broader range of activity than previously anticipated.

Animals↗
PubMed1987

Freeze-fracture study of the lateral-line canal organ of the Japanese sea eel, Lincozymba nystromi.

Specializations of apical surfaces of hair cells, supporting cells and marginal cells in the lateral-line canal organ of Japanese sea eel, Lincozymba nystromi, were examined with a freeze-fracture technique. Apical surfaces of hair cells have a lower density of intramembrane particles (IMP) than those of the surrounding supporting cells. Density of IMP on the stereocilia is almost the same as that on the apical surface of hair cells. Junctions between hair and supporting cells were tighter than those between two supporting cells; those between supporting and marginal cells were tighter than those between hair and supporting cells, and those between two marginal cells were the tightest in the lateral-line canal organ.

Animals↗