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Biomedical subjects

T Okada

Publications and source records attributed to T Okada.

At least 1,225 records · Page 68Linked to original sources
PubMed1977

Studies on the role of sympathetic nervous system in the mechanism of essential hypertension.

In order to investigate a role of sympathetic nervous system in the mechanism of blood-pressure elevation in essential hypertension, urinary catecholamines, serum dopamine-beta-hydroxylase (DBH) activity and a pressor response to infused noradrenaline (noradrenaline response) were measured, in the patients with essential hypertension, before and 2 weeks-rest after hospitalization or following salt restriction. In addition, plasma renin activity (PRA) and water-sodium contents were determined and a correlation between these variables and noradrenaline excretion, serum DBH or noradrenaline response was observed. A blood pressure fall after hospitalization was associated with a decrease of urinary noradrenaline and serum DBH, and there was a significantly positive correlation between the changes in blood pressure and those in urinary noradrenaline or in serum DBH. A significantly adverse correlation was found between plasma volume and the amounts of urinary noradrenaline excretion. The changes in noradrenaline response was negatively correlated with those in urinary noradrenaline excretion. In addition, noradrenaline response was correlated positively with plasma volume, extracellular fluid volume and total exchangeable sodium and negatively with PRA. Following salt restriction, a fall of the blood pressure was associated with an elevation of urinary noradrenaline excretion. The patients with more marked blood pressure fall showed a higher increase of urinary noradrenaline, and a significant correlation was found between the changes in these two variables. Noradrenaline response was significantly reduced, although it was not correlated significantly with noradrenaline excretion. In these experiments, adrenaline, unlike noradrenaline, did not show any obvious changes. These findings suggested that an excessive sympathetic nerve activity caused an elevation of blood pressure in the labile type of essential hypertension. It was demonstrated that a sympathetic nervous function was dependent on sodium intake and that there exisited a close relationship between noradrenaline response and water-sodium contents or PRA.

Adolescent↗
PubMed1977

Non-cholinergic, excitatory junction potentials in smooth muscle of chicken rectum.

Muscle strips from the longitudinal or circular muscle of the chicken rectum were used to determine changes in membrane potential during field stimulation as recorded using the sucrose-gap method. Stimulation with single square pulses (0.1 msec duration) evoked junction potentials elicited by transmitter released from nerve endings. Facilitation in amplitude of excitatory junction potentials (EJPs) was seen during repetitive stimulation in the longitudinal muscle, but in the circular muscle, EJPs reduced. Neither atropine nor hyoscine (up to 10(-5) g/ml) reduced EJPs. These drugs abolished the depression of EJPs in the circular muscle produced by repetitive stimulation. Anticholinesterases (2 X 10(--8)-2 X 10(-6) g/ml) reduced the EJPs. The inhibitory effect was produced without affecting the membrane resistance of smooth muscle and was completely antagonized by atropine (1-(-6) g/ml). Drugs that abolish the adrenergic functions did not affect the EJPs. These results suggest that nerves involved in the EJPs are non-cholinergic and non-adrenergic in nature, and the motor transmission to the smooth muscle may be inhibited by cholinergic nerves, presumably presynaptically.

Acetylcholine↗
PubMed1977

The intra-articular residual rate of 131I-fibrinogen and microautoradiographs of the synovial tissue in rheumatoid arthritis.

In this study, 131I-labeled human plasma fibrinogen (200 muCi) was injected intravenously into 21 patients with rheumatoid arthritis and 10 control patients without rheumatic diseases. The residual rates of radioiodinated fibrinogen in the knee joints were calculated by measuring with a scintillation counter the microautoradiographs of the synovial tissue obtained by punch biopsy from the knee joints. The residual rates in the knee joints without as well as with objective symptoms of RA were higher than in control patients. Radio-iodinated fibrinogen was demonstrated on the synovial villous surface, on the area of inflammatory cellular infiltration and stromal necrosis, and on the perivascular region of the synovial tissue from the knee joints of patients with RA, not only with, but also without clinical objective symptoms and histopathologic findings of fibrinoid necrosis, vascular superficial fibrinoid coating and fibrinoid degeneration of vascular wall. It is suggested that fibrinogen plays a role even in the early synovial tissue lesions of knee joints affected by RA.

Adolescent↗
PubMed1977

Effect of splenectomy in tumor-bearing mice and gastric cancer patients.

In order to investigate the effect of splenectomy on tumor growth, splenectomy was performed in DDS mice transplanted subcutaneously with Ehrlich ascites tumor cells before and after the transplantation. It was found that, in the first control group receiving sham operation, all the mice died of tumor; in the second group that underwent splenectomy 1 week before the transplantation the tumor regressed in every case; in the third group that received splenectomy 5 days after transplantation when tumor became established, the tumor regression was observed in 85% of the animals, and in the fourth group that underwent splenectomy 10 days after transplantation, all the animals died of tumor earlier than the sham-operated first group. In the follow-up observations of 389 patients with gastric cancer who underwent gastrectomy alone and 89 cases who received gastrectomy combined with splenectomy, the 5-year survival rate of the latter group tended to show a better prognosis in a relatively early stage. It was concluded that splenectomy might inhibit the growth of tumor in a certain early stage, in both animals and humans, and the possible mechanism of this effect of splenectomy was discussed from the immunological aspects.

Animals↗