Search PubMed⌕ Search

Biomedical subjects

Y Ohta

Publications and source records attributed to Y Ohta.

At least 1,081 records · Page 60Linked to original sources
PubMed1980

Inhibitory action of Ca2+ on spontaneous transmitter release at motor nerve terminals in a high K+ solution.

The inhibitory effect of a high external Ca2+ ([Ca2+]o) on spontaneous transmitter release in a high K+ solution (Gage and Quastel 1966; Birks et al. 1968) was studied at the frog neuromuscular junction, based on the hypothesis that an increased intracellular free Ca2+ ([Ca2+]i) in the nerve terminal plays a key role in the depression. Three procedures were employed to increase [Ca2+]i; increasing [Ca2+]o, application of caffeine and tetanic nerve stimulation. All of these procedures increased m.e.p.p. frequency in normal Ringer. However, as the basic m.e.p.p. frequency was increased by raising the external K+ concentration (7--15 mM), their facilitatory effects on m.e.p.p. frequency decreased, dissapeared and eventually reversed to depressant actions. Since a rise in the external K+ concentration would increase the steady state level of [Ca2+]i, it is suggested that when the [Ca2+]i is preset at a high level, manipulations so as to further increase [Ca2+]i depress spontaneous release of transmitter. Possible mechanisms for this inhibition was discussed in relation to a question whether or not the rate of spontaneous transmitter release is a monotonic function of [Ca2+]i.

Acetylcholine↗
PubMed1980

Five families with homozygous delta-thalassaemia in Japan.

Five families with delta-thalassaemia discovered in Ehime, Japan, are presented. The delta-thalassaemia was associated with a slight elevation of the level of Hb F in two families and with normal Hb F levels in three. Complete absence of HbA2 was found in the homozygous probands. No abnormal clinical or haematological findings were noted in the individuals with delta-thalassaemia.

Adult↗
PubMed1980

Electron-microscopic study on the development of permanently proliferated and cornified vaginal epithelium in mice treated neonatally with androgen.

In the vaginal epithelium of mice given 5 daily injections of 100 microgram 5 alpha-dihydrotestosterone from the day of birth, highly electron-dense cells with numerous cytoplasmic processes appeared in the basal layer within 35 days after the last injection. These cells were similar to the B cells reported in earlier works in neonatally estrogen-treated mice undergoing ovary-independent, permanent proliferation and cornification. The present electron-microscopic study suggests that the permanently proliferating, highly electron-dense cells are derived from electronlucent cells (clear cells) appearing in the basal layer of the vaginal epithelium 15-20 days after neonatal androgen treatment.

Age Factors↗
PubMed1980

Frequency and distribution of structural variants of hemoglobin and thalassemic states in Western Japan.

Hemolysates from 100,000 people who visited the Kyushu University Hospital and affiliated hospitals during the past 15 years were screened for hemoglobinopathies using electrophoresis on thin-layer starch gel; those exhibiting an abnormality were characterized further on clinical, biochemical, and genetic grounds. Of about 97,000 adult and 3,140 cord blood samples, 29 contained electrophoretically detectable abnormalities in the heterozygous condition. Another 17 samples had quantitative changes in the levels of the minor hemoglobin components. Of the thalassemic conditions, 12 involved beta-thalassemia, 3 alpha-thalassemia, 1 delta beta-thalassemia, and 1 delta-thalassemia. Among 45 carriers of beta-thalassemia from 12 families, 5 were noted to have thalassemia intermedia since they exhibited much more severe hemolytic syndromes than those with typical beta-thalassemia minor. The frequency with which we could detect a structural variant of Hb A in the adults by electrophoresis was one in 3,800 samples. About one in 8,000 carried a beta-thalassemia gene.

Adult↗
PubMed1980

Homozygous delta thalassemia in Japan.

Six families with delta-thalassemia have been found in Japan, in which 10 individuals are delta-thalassemia homozygotes with complete deficiency of Hb A2 and 18 individuals are heterozygotes with low levels of Hb A2. In three families with 10 individuals among these, persistence of fetal hemoglobin of Swiss type was observed. Almost all the members of these families were free from clinical symptoms and hematological abnormalities of the red cells.

Adult↗
PubMed1980

Comparative studies on the immunosuppressive effect among 5'-deoxy-5-fluorouridine, ftorafur, and 5-fluorouracil.

The immunosuppressive effect of 5'-deoxy-5-fluorouridine (5'-DFUR, Ro 21-9738) was examined for both humoral and cell-mediated immunity in mice in comparison with that of 5-fluorouracil and Ftorafur (FT-207). By both oral and intraperitoneal administration, 5'-DFUR was found to be much less suppressive than 5-fluorouracil and FT-207 in all immune responses tested; hemolysin plaque-forming cells, serum hemolysin titer, delayed-type hypersensitivity and allogeneic tumor rejection. Furthermore, 5'-DFUR did not induce any reduction in either the spleen weight, thymus weight, total spleen cell number, or peripheral leucocyte number.

Animals↗
PubMed1980

Simultaneous measurements of shifts of the center of gravity caused by ventilation and cardiac motions towards three body axes.

A method is described for the simultaneous measurements of three dimensional shifts of the gravitational center of the body caused by ventilatory and cardiac motions. The measuring system consists fundamentally of three load cells which support an aluminum die-casting platform. Measurement of the shift towards the X axis (front-to-back) was achieved by double integration of the outputs of load cells in order to convert acceleration into a shift of gravity. The records of a volunteer subjects measured with ECG and ventilatory flow showed two cardinal oscillations; one coinciding with the heat rate and the other with the ventilatory frequency. This became clear when recorded through either a low-pass or high-pass filter. Animal who breathed a SF6-O2 mixture into one side of the lungs or those with partial occlusion of a bronchus showed distinct changes in the pattern of the Y axis (right-to-left). These preliminary experiments convinced us that the system can serve as a non-invasive monitoring system of cardiopulmonary functions.

Animals↗
PubMed1980

Diffusion, convection and their coupling as gas transport mechanisms in the lungs: a model experiment.

The roles of diffusion and convection in gas transport were studied by means of a lung model with a hollow bronchial cast of a dog. He, Ar and SF6 were chosen as indicators with different diffusivities. Axial dispersion of a heavier gas was much better, but the concentration gradient in a static gas phase was greater for a heavier gas, i.e., there was a larger stratified inhomogeneity for a less diffusible gas. Crossings of He and SF6 concentration curves were observed between diffusion distances of 6 and 8 cm, which could be assumed to be a critical point of conversion where either convective mixing or diffusion favored gas transport. The results observed also suggested that the effective diffusion coefficient and speed of respiration affected the efficiency of gas transport.

Animals↗