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Biomedical subjects

H Higashi

Publications and source records attributed to H Higashi.

At least 235 records · Page 13Linked to original sources
PubMed1985

Noradrenaline mediates slow excitatory synaptic potentials in rat dorsal raphe neurons in vitro.

Repetitive focal stimulation to the slice surface within the region of the dorsal raphe (DR) nucleus of rat brain elicited a slow excitatory synaptic potential (slow EPSP), which followed a slow inhibitory synaptic potential (slow IPSP) in a majority of the DR neurons. The slow EPSPs were associated with either an increase of a decrease in membrane resistance. Noradrenaline (NA) application caused a membrane depolarization in most of the DR neurons. The NA-induced depolarization was also accompanied by either an increase or a decrease in membrane resistance. Both the slow EPSP and NA-induced depolarization were inhibited by phentolamine and prazosin but not by yohimbine and propranolol. The result suggests that slow EPSPs in rat DR neurons are mediated by NA interacting with an alpha 1-adrenoceptor.

Animals↗
PubMed1985

Selective depression of hippocampal inhibitory postsynaptic potentials and spontaneous firing by volatile anesthetics.

The effects of halothane, isoflurane and enflurane on the rat hippocampal CA1 neurons in in vitro preparations were studied by intracellular recordings. All volatile anesthetics, at the concentrations which are likely to be in the range of clinical doses, depressed the IPSPs and the spontaneous firing without affecting the resting membrane properties and the EPSPs. The results suggest that the simultaneous blocking effects of the anesthetics on both the spontaneous firing and IPSPs are responsible for production of general anesthesia rather than their blocking actions on the EPSPs in terms of behavior of hippocampal neurons.

Anesthetics↗
PubMed1985

Biosynthesis in vitro of disialosylneolactotetraosylceramide by a solubilized sialyltransferase from embryonic chicken brain.

A sialyltransferase involved in the biosynthesis in vitro of LD1c (NeuAc alpha 2-8NeuGc alpha 2-3Gal beta 1-4Glc-NAc beta 1-3Gal beta 1-4Glc-Cer) has been characterized from 9 to 11-day-old embryonic chicken brains. The CMP-[14C]NeuAc:LM1(alpha 2-8)sialyltransferase (SAT-2) sedimented (75%) at the junction of 0.75 and 1.2 M on a discontinuous sucrose density gradient when still membrane bound. In addition to the biosynthesis of LD1c, the detergent-solubilized (0.4% Nonidet P-40) preparation also catalyzes the transfer of sialic acid to O-8 of sialic acid in GM3 to form GD3 (NeuAc alpha 2-8NeuAc alpha 2 - 3Gal beta 1 - 4Glc - Cer). Substrate inhibition studies indicated that these two reactions are probably catalyzed by the same enzyme, SAT-2. The kinetic parameters of SAT-2 activity were determined. The Km values were 70 and 63 microM with CMP-[14C]NeuAc and LM1, respectively, when the detergent-solubilized supernatant fraction was used as enzyme source. The (alpha 2-8)-linkage between the terminal and penultimate sialic acids was determined using nonradioactive CMP-NeuAc and [Ac-14C]LM1 as substrates (Higashi, H., and Basu, S. (1982) Anal. Biochem. 120, 159-164) for the enzyme, followed by identification of the permethylated [14C]sialic acid of the product by radioautography. At 0.5 mM N-ethylmaleimide, the SAT-2 activity was inhibited 50% whereas SAT-1 and SAT-3 activities (Basu, M., Basu, S., Stoffyn, A., and Stoffyn, P. (1982) J. Biol. Chem. 257, 12765-12769) remained uninhibited.

Age Factors↗
PubMed1985

5-Hydroxytryptamine mediates inhibitory postsynaptic potentials in rat dorsal raphe neurons.

In rat dorsal raphe neurons, focal electrical stimulation elicited a slow inhibitory postsynaptic potential (IPSP) associated with increased membrane conductance. On the basis of data in the literature this IPSP is presumably caused by a recurrent inhibitory circuit. 5-Hydroxytryptamine (5-HT) application caused a hyperpolarization of the cell membrane, also associated with increased membrane conductance. Both responses could be abolished by lysergic acid diethylamide or methysergide, and enhanced by imipramine. The reversal potentials for the responses were at the same level of - 95 mV which suggests an increase in membrane potassium conductance as the mechanism of both responses. These data suggest that 5-HT may be the mediator of the IPSP evoked by focal stimulation.

Animals↗
PubMed1985

Characterization of N-glycolylneuraminic acid-containing gangliosides as tumor-associated Hanganutziu-Deicher antigen in human colon cancer.

Hanganutziu-Deicher (HD) antigen-active N-glycolylneuraminic acid (NeuGc)-containing gangliosides were isolated and characterized from human colon cancer tissues. The antigenic gangliosides were detected by thin-layer chromatography by our newly developed method (H. Higashi, Y. Fukui, S. Ueda, S. Kato, Y. Hirabayashi, M. Matsumoto, and M. Naiki. J. Biochem., 95: 1517-1520, 1984) of enzyme immunostaining using affinity-purified chicken antibody against hematoside containing NeuGc (II3NeuGc-LacCer) and horseradish peroxidase-conjugated rabbit anti-chicken lgG. One to six species of the antigenic gangliosides were isolated from seven of 16 cases of colon cancer, whereas no antigenic compound was detected in all apparently normal colorectal tissues from 17 individuals without colorectal cancer. Tissues from different patients showed different patterns of molecular species of the antigenic gangliosides. Densitometric determination indicated that HD antigenic sialic acid, NeuGc, accounted for about 1% or less of the total lipid-bound sialic acids. Four species of antigenic gangliosides were identified as hematoside and hematoside-containing O-acyl ester (II3NeuGc-LacCer and II3 4- or 7-O-acyl-NeuGc-LacCer), GM2-containing NeuGc (II3NeuGc-GgOse3Cer), and sialylparagloboside (IV3NeuGc-nLcOse4Cer) by their behaviors on 2-dimensional thin-layer chromatography, and the effects of mild alkaline treatment, sialidase treatment, periodate oxidation, and endo-beta-galactosidase treatment.

Antigens, Heterophile↗
PubMed1984

Characterization of N-glycolyneuraminic acid-containing glycosphingolipids from a Marek's disease lymphoma-derived chicken cell line, MSB1, as tumor-associated heterophile Hanganutziu-Deicher antigens.

Heterophile, Hanganutziu-Deicher (HD) antigen-active N-glycolylneuraminic acid-containing glycosphingolipids (GSLs) were detected as tumor-associated foreign antigens of a Marek's disease lymphoma-derived cell line, MSB1, by enzyme-immunoassay with chicken antibody against N-glycolylneuraminyl-lactosylceramide (anti-NeuGc-LacCer). At least three species of HD antigen-active GSLs were detected by two-dimensional thin-layer chromatography (TLC) combined with enzyme-immunoassay. The reactivities of the GSLs with anti-NeuGc-LacCer, their behaviors on two-dimensional TLC and the results of an endo-beta-galactosidase digestion study indicated that these three GSLs were NeuGc-LacCer (NeuGc alpha 2-2Gal beta 1-4Glc-Cer), NeuGc-nLcOse4Cer (NeuGc alpha 2-3Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4Glc-Cer) and NeuGc-nLcOse6Cer (NeuGc alpha 2-3Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4Glc-Cer).

Animals↗
PubMed1984

Sensitive enzyme-immunostaining and densitometric determination on thin-layer chromatography of N-glycolylneuraminic acid-containing glycosphingolipids, Hanganutziu-Deicher antigens.

A sensitive enzyme-immunochemical staining method was developed for detection of N-glycolylneuraminic acid (NeuGc)-containing glycosphingolipids (GSLs) on silica gel thin-layer chromatography. The procedure consists of immune reaction among NeuGc-containing GSLs, affinity-purified chicken anti-NeuGc-LacCer and horseradish peroxidase-conjugated rabbit anti-chicken IgG, and the peroxidase reaction using 4-chloro-1-naphthol as a chromogenic substrate. Quantitative determination was achieved by direct densitometric scanning of the enzyme-immunostained spots on the chromatogram. As little as 0.5 pmol of NeuGc-LacCer, NeuGc-nLcOse4Cer, and NeuGc-nLcOse6Cer (0.64-1.0 ng) could be detected with a good signal-to-noise ratio. A semi-linear detector response was observed up to 50 pmol of each GSL. This procedure can be applied easily to other glycolipid antigen systems.

Antigens, Heterophile↗
PubMed1984

Calcium-dependent after-potentials in visceral afferent neurones of the rabbit.

Intracellular recordings were made from neurones in nodose ganglia excised from rabbits. In C neurones, 1-60 action potentials were followed by an after-hyperpolarization with a peak amplitude of 16 mV and a time constant of decay ranging from 3 to 10 s. In A neurones, the action potentials were followed only by a brief (up to 50 ms) after-hyperpolarization. The after-hyperpolarization was associated with an increase in the membrane conductance to potassium ions; it reversed polarity at the potassium equilibrium potential. The increase in conductance following the action potentials was blocked by removal of calcium ions, or addition of cobalt to the extracellular solution. Intracellular injection of ethyleneglycol-bis(beta-aminoethylether)-N,N'-tetraacetic acid (EGTA) abolished the after-hyperpolarization; intracellular injection of calcium mimicked the after-hyperpolarization. It is concluded that calcium entry during the action potential leads to a long-lasting increase in potassium conductance in visceral afferent C neurones.

Action Potentials↗
PubMed1984

Tumor-associated expression of glycosphingolipid Hanganutziu-Deicher antigen in human cancers.

Expression of heterophile Hanganutziu-Deicher (HD) antigen on the cell surface of various human malignant tumor tissues was studied by membrane immunofluorescence staining with chicken antiserum against N-glycolylneuraminyllactosylceramide (HD3) and fluorescein-conjugated rabbit anti-chicken IgG. The HD antigen was demonstrated in samples from 38 of 77 (38/77, 49%) cases, consisting of gastric (9/16), breast (8/14), colorectal (3/12), nasopharyngeal (4/7), and uterine (2/3) carcinomas, leukemias (5/10), malignant lymphomas (2/5), and other cancers (5/10). Histological examination indicated that expression of the antigen by the gastric, colorectal and breast carcinomas and leukemias was not related to their histological types. The cytoplasm and the surface of the malignant glandular epithelial cells were both specifically stained by immunofluorescence staining of frozen sections in one colon adenocarcinoma. Glycosphingolipids (GSLs) were extracted from the colon cancer tissue and two HD antigen-active GSLs were detected on thin-layer chromatography (TLC) by enzyme-immunostaining using affinity-purified chicken anti-HD3 and horseradish peroxidase-conjugated rabbit anti-chicken IgG. One migrated to the same position as HD3 on TLC, and the other to a position similar to that of authentic N-glycolylneuraminylneolactotetraosylceramide.

Antigens, Heterophile↗
PubMed1983

On the mechanism of action of GABA in pelvic vesical ganglia: biphasic responses evoked by two opposing actions on membrane conductance.

Intracellular recording techniques were used to study the response of cat vesical pelvic ganglion neurones loaded with permeable anions to the application of GABA in vitro. In 106/127 neurones GABA evoked a biphasic response, the initial phase of which was depolarizing and associated with a conductance increase; the latter phase was hyperpolarizing and associated with a conductance decrease. The GABA evoked hyperpolarization and conductance decrease were related and behaved as though generated by closure of ion channels open in the resting membrane. The hyperpolarization had a strong inhibitory action on both spontaneous activity, and excitation evoked by depolarizing current injection and pre-synaptic nerve stimulation. Ion substitution experiments suggest that the conductance decrease is primarily to chloride ions, although other ionic species may contribute. Short iontophoretic applications of GABA-evoked monophasic depolarizing excitatory responses, even during the hyperpolarizing response evoked by perfusion of GABA, suggesting no cross-desensitization between the mechanisms generating the initial and late phases of the biphasic response.

Animals↗
PubMed1983

Hanganutziu-Deicher heterophile antigen in human retinoblastoma cells.

We investigated the possible existence of Hanganutziu-Deicher antigen (HD antigen) on retinoblastoma cells by means of indirect membrane immunofluorescence and a complement-dependent antibody-mediated cytotoxicity test. We prepared antiserum in the chicken by immunization with purified equine hematoside highly specific to HD antigen. Three kinds of retinoblastoma cell lines, Y-79, WERI-Rb 1, and TOTL-1, showed positive membrane staining. Y-79 and TOTL-1 cells were also confirmed by the cytotoxicity test to possess HD antigen. Retinoblastoma cells freshly isolated from two patients had a positive membrane immunofluorescence. These results indicated that HD antigen was expressed in human retinoblastoma cells in vitro as well as in vivo.

Antigens, Heterophile↗