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Biomedical subjects

H Tamura

Publications and source records attributed to H Tamura.

At least 559 records · Page 31Linked to original sources
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

Leucocytic movement and contractile protein.

In a study on leucocytic movement, it was found that leucocytes showed periodical dynamic patterns with each motile function, and a possible organization in their motile system. It was also clarified that the motile form and function of leucocytes were co-ordinately controlled by the intracellular level of ATP and that the characteristic contraction wave observed in moving leucocytes was substantial as a morphological manifestation of the contractile element in moving leucocytes. Based on these findings, an attempt was made to extract contractile protein from leucocytes. It was shown that the protein consisted mainly of myosin and actin, which is similar to protein of muscle. Thus, it was concluded that development of the pseudopod, which is indispensable for cell movement, seemed to result from liquid substance in the granuloplasm being squeezed out through contraction of contractile protein located in the surface layer of the granuloplasm. In non-muscular cells, the same type of ordered structure as seen in muscle has not been found yet, but it seems likely that the protein is capable of converting chemical energy into movement.

Actins↗
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

A cytologic study on small cell carcinoma of the esophagus.

The cytologic picture of small cell carcinoma primarily arising from the esophagus was studied with 7 cases which were confirmed by histologic examination. Cytomorphologic characteristics of small cell carcinoma of the esophagus are as follows: the arrangement of groups of tumor cells is irregular and overlapping with indistinct cell boundaries. The cytoplasm is small, or sometimes absent. The nuclei are round, oval or occasionally spindle shaped. Nuclear borders are thin. The chromatin of finely granular pattern has increased and is evenly distributed.

Aged↗
PubMed1978

Mitral valve replacement using a porcine xenograft for treatment of IHSS--A case report.

Recently we treated a 24-year-old female IHSS patient by mitral valve replacement, using a porcine xenograft valve. Following surgery, clinical manifestations improved markedly and postoperative cardiac catheterization revealed that the pressure gradient between left ventricle and aorta had dropped to a minimum compared with the pre-operative value of 104 mmHg and end-diastolic pressure of the left ventricle had returned to normal level.

Adult↗
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↗
PubMed1978

Intranuclear fibrillary inclusions in influenza pneumonia.

Electron microscopical study of the lung tissue from a 75-year-old man who died of influenza pneumonia (A/Victoria/RI/76) demonstrated fibrillary inclusions in the nuclei of many alveolar lining cells, in bronchial epithelial cells, and also in endothelial cells. These inclusions were morphologically different from those previously reported in experimental animals. In view of previous experimental studies indicating the necessity of nuclear participation in the replication of influenza virus, these inclusions may be virus-induced structures. Also, possibly the presence of these inclusions in the nuclei of many endothelial cells might be indicative of endothelial damage of microvessels and may be a pathogenetically important factor in influenza pneumonia.

Aged↗
PubMed1978

An analysis of the fatty acid composition of total lipids from mycoplasmas.

The fatty acid composition of the total lipids obtained from 9 species (22 strains) of Mycoplasma and 3 species (7 strains) of Acholeplasma was determined by gas-liquid chromatography (GLC). The major fatty acids of the Mycoplasma species were palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1), and linoleic acid (C18:2). Lauric acid (C12:0) and myristic acid (C14:0) were present in small amounts in this genus. For the Mycoplasma species, the most prevalent fatty acid was C16:0 or C14:0, and other leading fatty acids were C12:0, C18:0, C18:1 and C18:2. A substantial amount of C12:0 and C14:0 was found in the Acholeplasma species. It was confirmed that C12:0 and C14:0 were synthesized de novo, based on the fact that 14C-acetate was incorporated into these acids. The total percentage of C16 fatty acid was less than that of C18 fatty acids in all the strains of Mycoplasma and Acholeplasma except 4 strains. This may be related to osmo-regulation of the L-forms of Streptococci as mentioned in other reports.

Acholeplasma↗