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Biomedical subjects

H Takeuchi

Publications and source records attributed to H Takeuchi.

At least 973 records · Page 54Linked to original sources
PubMed1979

[Effect of oligopeptides containing L-Phe, L-Tyr, L-Trp, L-His or L-Met on the excitability of the 2 giant neurons of the African giant snail (Achatina fulica Ferussac)].

Effects of about ninety oligopeptides, containing L-Phe, L-Tyr, L-Trp, L-His and L-Met, on the excitability of two identifiable giant neurones (the PON, periodically oscillating neurone ; and the TAN, tonically autoactive neurone) of Achatine fulica Férussac were examined. Three oligopeptides, L-Lys-L-Phe-L-Tyr, L-Phe-L-Tyr and L-Phe-L-Trp, showed an inhibitory effect on the PON. However, this effect on the PON was weaker than that of the same three peptides on the TAN. [The latter has been reported in previous papers (1 to 3)]. Besides the three oligopeptides mentioned, four peptides, L-Phe-L-Phe, L-Phe-L-Phe-L-Phe, L-Tyr-L-Tyr and L-Tyr-L-Tyr-LTyr, still showed a weak inhibitory effect on the TAN in a high concentration.

Action Potentials↗
PubMed1979

Inhibitory effects of aromatic oligopeptides on the excitability of identifiable giant neurones of an African giant snail (Achatina fulica Férussac).

Effects of an aromatic tripeptide, L-Lys-L-Phe-L-Tyr and its related dipeptides on the excitability of two identifiable giant neurones (the TAN, tonically autoactive neurone and the PON, periodically oscillating neurone) in the suboesophageal ganglia of the African giant snail, Achatina fulica Férussac, were examined. Of 33 substances examined, three aromatic oligopeptides showed a marked inhibitory effect on the TAN excitability. The critical concentrations of these substances in bath application were: L-Lys-LPhe-L-Tyr (6.6 x 10(-6) approximately 2.2 x 10(-5) M), L-Phe-L-Tyr (9.1 x 10(-6) approximately 3.0 x 10(-5) M) and L-Phe-L-Trp (2.4 x 10(-5) approximately 7.3 x 10(-5) M). The microdrop application (100 micron in diameter) of a solution of the three inhibitory oligopeptides on the TAN surface hyperpolarized the TAN membrane potential and eliminated the spike discharges, in both the physiological and the chloride-free (replaced with acetate) conditions. The current-voltage relationships (I-V curve) of the TAN neuromembrane were measured by the injection of a transmembrane triangular current. The TAN I-V curve measured in the presence of L-Lys-L-Phe-L-Tyr or L-Phe-L-Trp was almost concordant to that of the normal state, if the two I-V curves were superimposed using the firing level as the reference point. The same three aromatic oligopeptides also showed an inhibitory effect on the PON excitability. The critical concentrations needed to produce the effects were much higher than those in the case of the TAN.

Animals↗
PubMed1979

Excitatory effects of ergot alkaloids and their derivatives on the excitability of an identifiable giant neuron of the African giant snail (Achatina fulica Férussac).

The effects of various ergot alkalids and related substances on the neuronal excitability were examined using a spontaneously firing neuron (PON, periodically oscillating neuron) identified in the suboesophageal ganglia of the African giant snail (Achatina fulica Férussac). Of the substances examined, ergometrine and methylergometrine had a marked excitatory effect on the neuron (their critical concentration by bath application: 5 x 10(-6) kg/l). D-lysergic acid (the critical concentration: 3 x 10(-5) kg/l), D-lysergic acid amide (3 x 10(-5), D-lysergic acid 3-hydroxypiperidinamide (3 x 10(-5) and D-lysergic acid 4-hydroxypiperidinamide (10(-4) had also an excitatory effect which was weaker than that of the two alkaloids mentioned above. Agroclavine and elymoclavine had a very slight excitatory effect in some cases. The other substances examined, for example, lysergine, 9, 10-dihydro-D-lysergic acid, 9, 10-dihydro-D-lysergic acid amide, nicergoline, metergoline, methysergide, ergotamine, bromocriptine, lergotrile etc., had no effect on the neuron at a high concentration (10(-4) kg/l). When local (microdrop) application of ergometrine and methylergometrine in the physiological state was performed, the depolarizing shift of the PON membrane and exaggeration of the membrane potential oscillations were observed. In the Na+-free (replaced with Li+) state, local application of the two effective alkaloids produced a marked frequency increase of tonic spike discharges with depolarization of the neuronal membrane.

Animals↗
PubMed1978

Current(I)-voltage(V) relationships of the neuromembrane of an identifiable giant neurone of an African giant snail (Achatina fulica Férussac) in the presence of an inhibitory tripeptide, L-Lys-L-Phe-L-Tyr.

An inhibitory tripeptide, L-Lys-L-Phe-L-Tyr, caused membrane hyperpolarization of the TAN (tonically autoactive neurone) resulting in an elevated firing level. The tripeptide, however, did not markedly affect either the TAN I-V curve or the firing pattern obtained by transmembrane triangular current injection.

Action Potentials↗
PubMed1978

Studies on morphological changes of arteries by administration of soluble immune complexes to low calcium diet bred guinea pigs.--Special reference to the morphological pathogenesis of arteritis.

Guinea pigs bred on a low calcium diet for 5 weeks, were injected soluble immune complexes once and angitis or angiolytic changes of the vascular wall in the lungs were noted. Leucocytic adhesions along the luminal surface of the vascular wall, which were carved with leucocytic reactions, could be noticed. Loosening or duplication of the basement membrane accompanied by protrusion of vascular smooth muscle cells into the subendothelial space could be demonstrated. Above results are thought to be a consequence of the conjugation of immune complexes and the negative charges of acid mucopolysaccharides.

Animals↗
PubMed1978

Studies on the formative mechanism of mesangiolytic changes of renal glomerulus induced by a low calcium diet breeding.

Mucopolysaccharides (MPS) are widely distributed in the connective tissues throughout the animal body. There are a lot of MPS classified both chemically and immunochemically and solutions of these various polysaccharides are characterized physicochemically by their high viscosity. In this study guinea pigs were bred on a low calcium diet of 0.2% for 13 weeks and the mesangiolytic changes of renal glomerulus--the partial cystic dilatation of the glomerular tufts with edematous loosening of the mesangial tissue were shown light microscopically. The less dense mesangial matrix with prominence of mesangial fibrils and small cytoplasmic projections of the mesangial cells were demonstrated electron microscopically. The formative mechanism of these mesangiolytic changes of renal glomerulus induced by a low calcium diet breeding will be discussed in this paper.

Animals↗
PubMed1978

Mechanisms of immune deposition in relation to a loosened molecular structure of acid mucopolysaccharides (aMP) caused by a low calcium diet--with special regard to their negative charges.

Diets used for breeding guinea pigs usually require 1.3--1.5% calcium. In the previous paper, guinea pigs bred on a low calcium diet of 0.2% for 4--6 weeks, showed mesangiolytic changes in the glomerulus. In this experiment, after breeding guinea pigs on a low calcium diet, soluble immune complexes which have positive charges in their structure, were injected once intravenously. By electron microscopy an increased amount of deposits in the basement membrane, in the subepithelial side of it, and in the mesangial matrix where they were loosened by a low calcium diet breeding, as reported in the previous paper, was noted. In this paper, mechanisms of immune deposition in relation to a loosened molecular structure of acid mucopolysaccharides, caused by a low calcium diet--especially their negative charges--will be discussed.

Animals↗
PubMed1978

Results of esophagocardioplasty with gastric patch in the treatment of esophageal achalasia.

Since 1968 esophagocardioplasty with gastric patch was employed in 57 patients as a primary operation for achalasia of the esophagus and eight patients with previous operations for achalasia. Satisfactory results were obtained in follow-up studies up to eight years. The results indicate that this procedure is successful in dilating the lower part of the esophagus and esophagocardiac junction without interfering with their proper functions. This provides better passage through the junction with preservation of the mechanism which prevents reflux.

Adult↗
PubMed1978

In vivo interaction between steroidal alkylating agents and oestrogen receptors in rabbit uteri.

The binding of steroidal alkylating agents to specific tissue component is necessary for the selective distribution of these compounds to their target tissues. The in vivo interaction of Estracyt or NSC-112259 with oestrogen receptors may play an important role in their action mechanism. Both Estracyt and NSC-112259 which were administered in vivo, gradually reduced the binding of [3H] oestradiol to cytoplasmic oestrogen receptor in rabbit uteri. From this, it was suggested that a negligible amount of oestradiol was released from these compounds and that the oestradiol moiety was useful as a carrier for the nitrogen mustard moiety. And it appeared that the synthesis of a new receptor protein was inhibited by the nitrogen mustard moiety, thereby causing a decrease in the cytoplasmic oestrogen receptor level.

Animals↗
PubMed1978

[Inhibitory effects of dipeptides containing tryptophan on the excitability on the giant neuron of the giant African snail (Achatina fulica, Ferussac)].

Besides an inhibitory effect of L-Lys-L-Phe-L-Tyr and L-Phe-L-Tyr, L-Phe-L-Trp showed the same effect on the excitability of a giant neurone (the TAN, tonically autoactive neurone) identified in suboesophageal ganglia of Achatina futica Férussac. The critical concentration of L-Phe-L-Trp to produce the effect was 10(-5)--3 X 10(-5) kg/1. The inhibitory effect of this substance was relatively slow and independent no chloride ions, as well as in the case of L-Phe-L-Tyr. L-Trp-L-Phe, Gly-L-Trp and L-Trp-Gly did not show any effect on the same neurone. The I-V curve of the TAN's neuromembrane, measured by the injection of a transmembrane triangular current, were not modified markedly by L-Phe-L-Trp at 4 X 10(-4) kg/1. The pattern of the TAN's spike firing produced by the depolarizing current injection were not influenced by this substance.

Animals↗