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Biomedical subjects

H Higashi

Publications and source records attributed to H Higashi.

At least 253 records · Page 14Linked to original sources
PubMed1983

A new method for purification of anti-glycosphingolipid antibody. Avian anti-hematoside (NeuGc) antibody.

A new method for purification of anti-glycosphingolipid antibodies had been developed. N-Glycolylneuraminyl(alpha 2-3)lactosylceramide [hematoside (NeuGc)] could be hydrophobically bound on octyl-Sepharose 4B in the presence of 0.1 M KCl. The Sepharose gel coated with hematoside (NeuGc) was used as immunoadsorbent for affinity column chromatography to purify avian anti-hematoside (NeuGc) antibody. The procedure is very simple, reproducible and applicable to purification of almost all anti-glycosphingolipid antibodies. The glycosphingolipid used for the affinity chromatography could be recovered without any destruction by successive extraction of the gel with methanol and methanol/chloroform (1:2, v/v).

Animals↗
PubMed1983

Voltage-dependent activation of potassium current in Helix neurones by endogenous cellular calcium.

1. The effect of endogenous Ca on potential-dependent K current IKD, was examined in identifiable neurones of Helix aspersa. The suction pipette method of internal perfusion was used along with a combined voltage-clamp method in which the membrane potential was measured by a separate glass micro-electrode and the current was passed by the suction pipette. Activation of the potential-dependent A current, IA, was prevented by using holding potentials of -40 mV where IA is inactivated and by the addition of the A-current blocker 4-aminopyridine. Activation of K currents by transmembrane Ca current, IKCa, was suppressed by Co substitution for Ca ion extracellularly. 2. Under these conditions, IKD rose to a peak value and then subsided to a steady level. The current-voltage (I-V) relationship for peak IKD had an upward bump at about +50 mV that gave it an S-shape. The I-V curve for steady IKD rose continuously. Peak and steady IKD were reduced by perfusing with EGTA or F ions intracellularly. The EGTA effect occurred at intracellular Ca activity levels below 10(-7) M. Increases in the concentration of EGTAi at constant Cai had no additional effect; however, recovery experiments do not allow us to rule out some direct action of EGTA on IKD. 3. Prolonged extracellular perfusion with Co-substituted solutions also reduced IKD and the effects occurred more quickly when the solutions were made hypertonic or caffeine was added to them. The peak transient was abolished, and the small remaining steady IKD (about 5-10% of normal peak IKD) was blocked by tetraethylammonium. IKD could be restored by the temporary reintroduction of Ca in the extracellular solution. 4. The S-shape of the peak I-V relationship for IKD may be due to Ca released from an endogenous site by membrane depolarization. The reduction of steady and peak IKD to very low values by Ca chelators or prolonged perfusion with Ca-free solutions indicates that Cai is important for activation of these K channels. 5. Three cellular structures were identified in electron micrographs of freeze-fractured neurones that could be involved in potential-dependent endogenous Ca release. These were a restricted extracellularly space, an intracellular membrane system of endoplasmic reticulum that may be fused to the internal face of the plasma membrane (the subsurface cisterns of Henkart & Nelson, 1979), and intracellular vesicles that also may be fused to the plasma membrane.

Animals↗
PubMed1982

Morphine enhances and depresses Ca2+-dependent responses in visceral primary afferent neurons.

Morphine at 1 to 100 nM enhances and depresses Ca2+-dependent potentials, the shoulder of the action potential, the hyperpolarizing afterpotential, and the calcium spike in visceral primary afferent neurons of rabbits. These effects could be reversed by naloxone. The enhancement and depression of the Ca2+-dependent potentials are not only concentration-dependent but they are also time-dependent and can be observed with a given concentration of morphine.

Action Potentials↗
PubMed1982

Specificities of human heterophilic Hanganutziu and Deicher (H-D) antibodies and avian antisera against H-D antigen-active glycosphingolipids.

The precise specificities H-D antibodies and newly obtained avian antisera to the H-D antigen-active glycosphingolipids. N-glycolylneuraminyl (alpha 2-3) lactosyl ceramide (hematoside) and N-glycolylneuraminyl (alpha 2-3) lactoneotetraosyl ceramide (sialosylparagloboside) were compared by gel precipitation and hemagglutination inhibition using other gangliosides with a related structure and chemically modified hematoside derivatives and the oligosaccharides from both the antigenic glycosphingolipids. Human H-D antibodies were found to have the same affinity for both antigenic glycosphingolipids; however, the avian anti-hematoside or anti-sialosylparaglobosides showed a higher affinity for the homologous antigen. Human H-D antibodies were directed more exactly toward the terminal sialic acid residue and more roughly to the hydrophobic portion of both compounds; however, the two avian antibodies were directed more specificity to the whole structure of the homologous antigen glycosphingolipid.

Animals↗
PubMed1982

Chemoreceptors for serotonin (5-HT), acetylcholine (ACh), bradykinin (BK), histamine (H) and gamma-aminobutyric acid (GABA) on rabbit visceral afferent neurons.

The somata of type 'C' neurons in rabbit nodose ganglion are endowed with receptor sites for 5-HT, BK, ACh, II and GABA. 5-HT and ACh application to type 'C' neurons in the nodose ganglion of rabbits produced a rapid depolarization associated with an increased membrane conductance, most likely to Na+ and K+. BK and H elicited slow depolarizations accompanied by a decreased membrane conductance probably to K+. GABA induced a rapid depolarization associated with an increased conductance to Cl-. In contrast, type 'A' neurons were insensitive to the four algesic agents but responded to GABA. d-Tubocurarine or picrotoxin at relatively low concentrations blocked ACh, 5-HT and GABA depolarizations without affecting membrane properties. Hexamethonium blocked ACh responses but not 5-HT responses. In addition, no desensitization occurred between the substances 5-HT, ACh or BK. The results suggest that the depolarizing effect of these agents on visceral neurons might be exerted via different receptors.

Acetylcholine↗
PubMed1982

5-Hydroxytryptamine receptors of visceral primary afferent neurones on rabbit nodose ganglia.

1. The electrophysiological characteristics of 5-hydroxytryptamine (5-HT) receptors distributed on visceral primary afferent neurones (the nodose ganglion cells of the vagus) in rabbits were investigated with intracellular recording and voltage-clamp techniques.2. In response to 5-HT applied by superfusion (>/= 10 mum) or by ionophoresis (>/= 5 nA, 50 msec), the majority of type C neurones (mean axonal conduction velocity: 0.83+/-0.25 m/sec) showed a rapid depolarization of 20-30 mV in amplitude which was followed by a hyperpolarization of a few millivolts. Both the initial depolarization and afterhyperpolarization were associated with a reduction in membrane resistance.3. Type A neurones (mean axonal conduction velocity: 7.7+/-0.4 m/sec) did not show any significant alterations in membrane potential and resistance during or after application of 5-HT.4. The initial depolarization induced by 5-HT was abolished by Na(+)-free Krebs solution and showed a reduction of a few millivolts in K(+)-free or Ca(2+)-free Krebs solution. The response in normal Krebs solution was reversed at a membrane potential level of +7.3+/-1.1 mV.5. The afterhyperpolarization disappeared in Na(+)-free or Ca(2+)-free Krebs solution, while it was markedly enhanced in K(+)-free Krebs solution. The response in normal Krebs solution reversed at a membrane potential of -88.7+/-0.8 mV, and was abolished at membrane potentials more positive than -20 mV.6. Unlike 5-HT voltage responses, which were biphasic in the majority of neurones examined, 5-HT induced currents were usually monophasic when recorded at holding membrane levels ranging from -80 to +50 mV. The reversal potential of the inward current was +7.5+/-0.8 mV which was in good agreement with the reversal level for 5-HT-induced depolarizations. The reversal potentials for inward currents which were obtained at various concentrations of Na(+) or K(+) corresponded to the theoretical values calculated by the equivalent circuit equation.7. These results suggest that the initial depolarization induced by 5-HT is due mainly to simultaneous increases in Na(+) and K(+) conductances, while the afterhyperpolarization is brought about by an increase of K(+) conductance which is triggered by a voltage-dependent influx of Na(+) and Ca(2+).8. The mean value for the ;limiting slope' of conductance change vs. 5-HT concentration and the slope of 5-HT current vs. 5-HT concentration obtained by superfusion of 5-HT, were in good agreement, 1.84+/-0.26 and 1.88+/-0.31, respectively. On the other hand, the mean Hill coefficient obtained from the dose-response curves for the inward current induced by ionophoresis was 2.51+/-0.14.9. Tetrodotoxin (0.2 mum) blocked the soma action potential completely, but did not show any effect on 5-HT-induced responses.10. (+)-Lysergic acid diethylamide and methysergide (1-100 mum) had no depressant effect on the 5-HT-induced depolarization.11. (+)-Tubocurarine at low concentrations (1-5 mum) inhibited the 5-HT induced inward current competitively. The mode of its inhibitory action became noncompetitive at higher concentrations (10-20 mum).

Animals↗
PubMed1982

Effect of barbiturates on the GABA receptor of cat primary afferent neurones.

1. The effects of the barbiturate anaesthetics, pentobarbitone and thiopentone, on the membrane properties and the gamma-aminobutyric acid (GABA)-induced responses of cat primary afferent neurones were studied with intracellular recording and voltageclamp techniques.2. At low concentrations (10(-7)-10(-5) M) both barbiturates slightly enhanced and prolonged GABA-induced depolarizations or currents without affecting the membrane properties. At these concentrations, barbiturates have no effect on the apparent dissociation constant of the GABA-GABA receptor interaction or the reversal potential for GABA-induced depolarizations or currents.3. At high concentrations (10(-4)-10(-3) M) barbiturates produced a few millivolts reduction in the resting membrane potential. Voltage-clamp analysis revealed that the depolarization was associated with one of the three types of conductance change, i.e., an initial increase followed by a decrease (40% of neurones examined), only an increase (40%) and only a decrease (20%).4. Analysis in different ionic media indicated that the depolarization with a reduced membrane resistance is associated with an increased chloride conductance and that the one with an increased membrane resistance is accompanied by a reduction in potassium conductance. Bath-application of GABA (10(-3) M) or picrotoxin (10(-5) M) inhibited the increase in chloride conductance but not the reduction in potassium conductance.5. Barbiturates at these high concentrations initially caused a marked augmentation and prolongation of GABA responses; this was followed by a depression. The depressant action did not appear to be voltage-dependent. These actions of barbiturates were not accompanied by changes in the apparent dissociation constant of the GABA-current dose-response curve or the reversal potential for GABA currents. In addition, the single exponential decay of GABA current was not changed despite a marked prolongation of its decay time.6. Picrotoxin (10(-5) M) antagonized the depressant effect of barbiturates at high concentrations on GABA currents, and barbiturates (5 x 10(-6) M) reduced the inhibitory action of picrotoxin (5 x 10(-6) M) on the GABA-currents.7. From all these results, it is suggested that the site of barbiturate actions on GABA-responses is mainly the allosteric site (the ionic conductance regulatory subunit) but not the agonist recognition site or the chloride channels linked with GABA receptors.

Action Potentials↗
PubMed1982

Hanganutziu-Deicher type-heterophile antigen-positive cells in human cancer tissues demonstrated by membrane immunofluorescence.

The possible expression of Hanganutziu-Deicher (H-D)-type heterophile antigen on the cell surface of several types of human cancer tissues was investigated by the membrane immunofluorescence test with anti-H-D serum. Anti-H-D serum of high titer was obtained from chickens immunized with H-D antigen-active glycosphingolipid, N-glycolylneuraminyl-lactosylceramide (equine hematoside). H-D antigen was demonstrated in 3 to 6 gastric cancer tissues, 2 of 3 lung cancer tissues, and 2 of 4 breast tissues examined, but not in 5 colorectal cancer tissues examined.

Antigens, Heterophile↗
PubMed1981

The effects of neuroleptics on the GABA receptor of cat primary afferent neurons.

Butyrophenones (haloperidol and pimozide) at low concentrations (0.05-1.0 micro M) inhibited the GABA-induced depolarization of cat primary afferent neurons, while at high concentrations (greater than 10 micro M) they enhanced the GABA-depolarization. These actions of the butyrophenones were not accompanied by any measurable change in the dissociation constant of the GABA-GABA receptor interaction, whereas their inhibitory and facilitatory influences on the GABA-depolarization were associated with reduction and increase in the cell membrane resistance, respectively. Further analysis showed that the reduction of membrane resistance by low concentrations of butyrophenones was brought about by an increased sodium and potassium conductance and that the increase in membrane resistance by a high concentration of these drugs was caused by a reduced sodium and potassium conductance. In contrast to the butyrophenones, a typical phenothiazine derivative (chlorpromazine) at concentrations of 0.1-100 micro M did not affect the GABA-depolarization. The results suggest that butyrophenones do not mimic the action of GABA as originally proposed by Janssen, but alter the GABA-induced depolarization indirectly by modifying the electrically excitable portion of the cell membrane. Chlorpromazine, a phenothiazine, on the other hand, has no recognizable effects on either the GABA-receptor membrane or the electrically excitable membrane.

Afferent Pathways↗
PubMed1981

Effects of perhexiline on myocardial phosphorylase activity, myocardial catecholamine content and heart rate.

A study was conducted on the effects of perhexiline on myocardial phosphorylase activity, myocardial catecholamine content and heart rate. Phosphorylase a activity and heart rate were investigated as an indicator of sympathetic nerve tone in order to clarify the characteristic of perhexiline with regard to the effects on myocardial metabolism in hyperthyroid rats and catecholamine deficient rats. Myocardial catecholamine and phosphorylase a activity were measured by von Euler's method and Cori's method respectively. Conclusion of this study are summarized as follows: 1) Perhexiline reduces the heart rate, and its effect is not always dependent upon the changes in myocardial norepinephrine content. 2) Perhexiline reduces myocardial phosphorylase a activity. It cannot be always said that the reduction is dependent upon the changes in myocardial norepinephrine. 3) Though slightly different from propranolol and dichloroisoproterenol, perhexiline possesses cardiac effects resembling beta-blockers.

Animals↗