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Biomedical subjects

H Tamura

Publications and source records attributed to H Tamura.

At least 541 records · Page 30Linked to original sources
PubMed1980

The effects of aromatic amino acid derivatives on the excitability of an identifiable giant neurone of the African giant snail (Achatina fulica Férussac).

1 The effects of derivatives of aromatic amino acids on the excitability of an identifiable giant neurone (TAN, tonically autoactive neurone) of the African giant snail (Achatina fulica Férussac) were examined. 2 The following substances had marked inhibitory effects on TAN using bath application: N-beta-phenylpropionyl-L-Tyr and N-beta-phenylpropionyl-L-Trp (critical concentration, 3 x 10(-7) M), N-beta-phenylpropionyl-L-Phe, N-cinnamoyl-DL-Trp and N-phenoxyacetyl-L-Trp (critical concentration, 10(-5) to 3 x 10(-5) M). However, N-beta-phenylpropionyl-D-Tyr and N-beta-phenylpropionyl tyramine had no effect. 3 Microdrop (150 micrometers in diameter) application of N-beta-phenylpropionyl-L-Tyr or N-beta-phenylpropionyl-l-trp containing about 100 pg resulted in marked inhibitory effects on TAN. The effect was observed in Ca2+-free, Mg2+-rich (24 mM) solution. Substitution of Cl- by acetate did not alter the response. This indicates that the two substances act directly on the TAN membrane and not via synaptic influences, and that the inhibition produced by the two substances is not due to the permeability increase of the TAN membrane to Cl-.

Amino Acids↗
PubMed1980

[Reproductive ability of germfree ICR female mice (author's transl)].

Reproductive ability of germfree and conventional female ICR mice was examined. Litter size and number of fetuses of germfree ICR mice kept in Facility A were smaller than those of Jcl: ICR mice. No difference was seen in oestrous cycle, pregnant rate, gestation period, weaning rate and number of corpora lutea between germfree and conventional mice. The small litter size of germfree mice seemed to be associated with early embryonic death before implantation. On the other hand, litter size of ex-germfree mice did not increase after conventionalization in Facility B.

Animals↗
PubMed1980

Drug resistance of organisms isolated from feces of laboratory mice and rats.

A total of 248 strains of EScherichia coli, 132 of Staphylococcus epidermidis, 137 of Streptococcus faecalis and 89 of STr. faecium were collected from feces of 40 mice and 36 rats of 8 colonies in 1978, and drug resistance were examined by an agar dieution method using 23 antibiotics. The results indicated a positive relation between use of antibiotics and appearance of multiple drug resistant organisms.

Animals↗
PubMed1980

[The weights of genital organs in germfree and conventional ICR mice administered with hCG, estradiol benzoate, progesterone and testosterone propionate (author's transl)].

Female germfree (Gf) and conventional (Cv) ICR mice aged 21-25 days were administered with hCG (50IU/head/day for 2 days). Six hours after the last administration, uterine weights of Gf and Cv mice were 175.8 mg% and 238.7 mg% respectively, the difference between Gf and Cv animals was statistically significant (p less than 0.05). Ovariectomized Gf and Cv mice aged 80-150 days were successively administered with estradiol benzoate (0.02 mg/head/day for 5 days). Six hours after the last administration, uterine weights of Gf and Cv mice were 358.8 mg% and 462.7 mg% respectively, being statistically significant between Gf and Cv animals (p less than 0.01). After administration of estradiol benzoate (0.02 mg/head/day for 2 days), 1.0 mg/head/day of progesterone for 3 days were given ovariectomized Gf and Cv mice aged 80-150 days. Six hours after the last administration, uterus of Gf and Cv mice were weight 337.6 mg% and 423.5 mg% respectively, the difference was statistically significant (p less than 0.01). Castrated Gf and Cv mice aged 80-150 days were administered with 1.0 mg of testosterone propionate (head/day for 5 days). Six hours after the last administration, weights of seminal vesicle and coagulating gland of Gf and Cv mice were 376.0 mg% and 611.8 mg% respectively, the difference was statistically significant (p less than 0.01).

Animals↗
PubMed1980

[Different effects of the replacement of extracellular sodium with lithium on the abnormal spike discharges caused by 2 convulsants, Metrazol and strychnine, on an identifiable giant neuron of the mollusc Achatina fulica Ferussac].

The influences of the replacement of sodium with lithium in the extracellular medium on the abnormal spike discharges, caused by two convulsants, metrazol and strychnine, of a giant neurone (TAN, tonically autoactive neurone) identified in the suboesophageal ganglia of the African giant snail (Achatina fulica Férussac) were examined. The slow oscillations of potential caused by metrazol disappeared after this replacement. On the other hand, the abnormal action potentials caused by strychnine, as well as the normal action potentials, still remained after the removal of sodium in the medium.

Action Potentials↗
PubMed1980

[Effects of clavines, ergot alkaloids, on the membrane potential of an identifiable giant neuron of the African giant snail Achatina fulica Ferussac].

The effects of seven clavines, alkaloids of ergot, on the electrical activity of an identifiable giant neurone (TAN, tonically autoactive neurone) of the African giant snail were examined. All the substances examined, lysergine, agroclavine, elymoclavine, festuclavine, chanoclavine, rugulovasine A and rugulovasine B, at 2 X 10(-4) kg/l have no constant effect on TAN, indicating that they have no direct effect on this neurone. However, the substances examined, except for chanoclavine, in the same concentration occasionally caused the transient depression with an augmentation of trans-synaptic influences. This depression may be due to the trans-synaptic influences. The four substances examined, lysergine, agroclavine, elymoclavine and festuclavine, in the same concentration produced TAN abnormal spike discharges, doublet or triplet spikes.

Animals↗
PubMed1980

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

The effects of ergot alkaloids and their derivatives on the excitability of an identifiable giant neurone, TAN (tonically autoactive neurone), found in the suboesophageal ganglia of the African giant snail (Achatina fulica Férussac) were examined. Ergometrine and methylergometrine had the strongest inhibitory effects. The critical concentrations were 3 X 10(-5) approximately 10(-4) kg/l. The three hydrogenated ergot derivatives, 9, 10-dihydroergocristine, 9, 10-dihydroergocryptine and 9, 10-dihydroergocornine, had weaker inhibitory effects than those of ergometrine and methylergometrine. The other substances examined, including D-lysergic acid, D-lysergic acid amide, D-lysergic acid piperidinamide, had no effect. Some of the substances examined, for example, lysergine, agroclavine, elymoclavine, nicergoline, ergotamine, bromocriptine and lergotrile, at high concentrations occasionally caused transient inhibition immediately after their application. This inhibition may be due to the synaptic influences produced by the excitation of other neurones. Some of the substances examined, lysergine, agroclavine, elymoclavine, festuclavine, nicergoline and lergotrile, at high concentrations caused abnormal spike discharges of TAN such as doublet or triplet spikes.

Animals↗
PubMed1979

Inhibitory effect of tripeptides containing L-Phe-L-Tyr on neuronal excitability.

Eight tripeptides containing L-Phe-L-Tyr were synthesized, and their effects on the excitability of a giant neurone (tonically autoactive neurone, TAN), identified in the suboesophageal ganglion of an African giant snail (Achiatina fulica Férussac), were examined. Of these tripeptides, the following three showed a marked inhibitory effect: L-Glu-L-Phe-L-Tyr (most effective; critical concentration: 3 X 10(-6)--10(-5) M), Gly-L-Phe-L-Tyr and sarcosine-L-Phe-L-Tyr. The TAN inhibition caused by L-Glu-L-Phe-L-Tyr was not due to an increased membrane permeability to chloride ions.

Animals↗
PubMed1979

Gross and histological types of early gastric carcinomas in relation to the acid-secreting area.

The relation of gastric acid-secreting function to the gross and histological types and locations of carcinomas was examined in 53 patients with early gastric carcinomas. Studies were made by the endoscopic Congo red test developed in this clinic. Results indicated a close correlation between the gross and histological types of early gastric carcinoma and the extent of the acid-secreting area. In general, when the acid-secreting area was large, the carcinomas were ulcerated and histologically undifferentiated and they were chiefly located in nonacid-secreting areas adjacent to acid-secreting areas, or sometimes they were surrounded by acid-secreting areas. On the contrary, when there was little or no acid-secreting area the carcinomas were polyploid and histologically differentiated, and they were located in nonacid-secreting areas far from acid-secreting areas.

Adenocarcinoma↗
PubMed1979

Relation of intestinal metaplasia to the acid-secreting area.

The distribution of intestinal metaplasia in relation to the acid-secreting are was investigated in 66 patients not suffering from gastroduodenal diseases. Studies were made via the endoscopic Congo Red test in combination with the methylene blue staining method. In this test, the acid-secreting area is identified as a "discolored" area in which Congo Red turns from red to blue-black, and areas of intestinal metaplasia were observed as areas staining blue with methylen blue. A close relationship was found between the acid-secreting area and the distribution of intestinal metaplasia; in general, intestinal metaplasia tended to be more extensive and more frequent when the acid-secreting area was small. It was also found that intestinal metaplasia increased with age. However, even in patients who were over 40 years of age, intestinal metaplasia was seen in 12.5% only, if the acid-secreting area was large. Hence, it appears likely that development of intestinal metaplasia is more closely related to the acid-secreting function than to aging.

Adult↗
PubMed1979

Correlation of tartrazine hypersensitivity with specific serum IgD levels.

The clinical diagnosis of hypersensitivity to the food dye tartrazine in 16 subjects correlated with levels of tartrazine-specific IgD antibodies determined by a solid phase radioimmunoassay inhibition test. This is the first study associating hypersensitivity to a low molecular weight chemical with an antibody response of the IgD class. There was little or no correlation between clinical sensitivity and IgE antibodies.

Antibody Formation↗
PubMed1979

Vitamin B2 activity of 7,8-dimethyl-10-(2,3,4-trihydroxy-4-formylbutyl)isoalloxazine in Lactobacillus casei.

The microbial activities of vitamin B2-aldehyde and vitamin B2-acid, produced by Schizophyllum commune, a Basidiomycete, were studied. Lactobacillus casei ATCC No. 7469 was used as a test microorganism. B2-aldehyde exhibited a good response curve in the growth of L. casei. B2-acid had neither a stimulatory nor an inhibitory effect on the growth. When B2-aldehyde was incubated with the homogenate of L. casei, it was converted to riboflavin. The flavin formed from B2-aldehyde by the homogenate not only exhibited an equivalent response curve to authentic riboflavin in the growth of L. casei, but also showed the same Rf value as authentic riboflavin in any paper chromatogram, as far as tested. Hence, the microbial activity of B2-aldehyde for L. casei seems to be ascribable to riboflavin which is a reduction product of B2-aldehyde.

Dose-Response Relationship, Drug↗
PubMed1979

[Effects of 2 water-soluble contrast media, meglumine iothalamate (Conray) and meglumine iocarmate (Dimer-X), on the electric activity of identifiable giant neurons of the African giant snail (Achatina fulica Ferussac)].

The influences of two water soluble contrast media, meglumine iothalamate and meglumine iocarmate, on the neuronal excitability and on the neuronal sensitivity to putative transmitters were examined in comparison with those of sucrose using two identifiable giant neurones of Achatina fulica Férussac (the TAN and the PON). A relatively low increase of osmotic pressure of the extracellular fluid, produced by the application of contrast media, reversed the Cl- dependent inhibition caused by a putative transmitter. The same increase of this osmotic pressure, however, did not influence the Cl- independent inhibition and the excitation of the neurone examined. The hyperpolarization of neuromembrane was caused by an increase of osmotic pressure of the extracellular fluid. Its relatively high increase was necessary to make spontaneous spike discharges disappear totally. All effects of the two contrast media, observed in this study, were due to the increase of osmotic pressure of the extracellular fluid ; no specific effect of the contrast media containing the iodine on the indicators used was observed.

Action Potentials↗
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↗