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Biomedical subjects

M Sakaguchi

Publications and source records attributed to M Sakaguchi.

At least 487 records · Page 27Linked to original sources
PubMed1979

A photoelectric diameter gauge utilizing the image sensor.

We have designed and constructed a blood vessel diameter gauge, utilizing a high resolving power and stability of the image sensor which has become of major interest lately as a new photoelectric transducer. The distinct feature of the gauge is summarized as follows. (1) Contact-free measurements of blood vessel diameter (1--14 mm) are possible. (2) The cuff-type probe is small in size and easy to put to use. (3) The lightguide consisting of optical fibers makes incident light cold. (4) The resolving power of the gauge is 28 micrometer in principle. (5) The frequency response of the gauge is flat up to 100 Hz. A few results of its preliminary application to in vitro and in vivo experiments are also demonstrated.

Animals↗
PubMed1979

Effect of microvibration on activity of ureteral and portal smooth muscles.

Spontaneous contractions were elicited by microvibrations (1--80 Hz, 50--400 micron) imposed upon quiescent ureter and portal venous smooth muscles of dogs. The microvibrations increased the rate of spontaneous contractions. A microvibration of larger amplitude gave rise to a more profound increase at each frequency. The acceleration was often accompanied by a reduction in contractile force. The positive chronotropic effect was enhanced by increases in frequency from 20 to 40 Hz and not affected by administration of autonomic blocking agents and tetrodotoxin, but disappeared in a Ca-free environment and reappeared on addition of Ba2+. the simulating action of microvibration was almost proportional to external Ca2+ concentrations ranging from 2.2 to 6.2 mM. The microvibrations were able to elicit spontaneous activity in the preparation, which had been made quiescent by administration of Mn2+. These findings suggested that the positive chronotropic effect may be closely related to an increased Ca2+ influx through the membrane of smooth muscle. Active tension in the ureter in a state of contracture was depressed by imposed microvibrations.

Action Potentials↗
PubMed1978

Vibration-induced hyperresponsiveness of arterial smooth muscle to noradrenaline with special reference to Raynaud's phenomenon in vibration disease.

Effects of in vitro and in vivo vibratory stimulations were studied on dose-response relationships of noradrenaline in excised femoral arteries of dogs and rats. The responsiveness of these arteries were enhanced after the application of the stimulation. The degree of the hyperresponsiveness was dependent upon frequency, amplitude, and duration of the stimulation. Based on the experimental results, a possible explanation was offered for Raynaud's phenomenon in vibration disease.

Animals↗
PubMed1978

External small-field irradiation of cervical carcinoma with linear accelerator.

Since 1966, 125 patients with carcinoma of the uterine cervix were treated with a 6 MV roentgen beam from a linear accelatro. The pelvis was irradiated with 60 Gy followed by 30 to 45 Gy to a small volume using a lateral pendulum. The small-field irradiation was performed using a new beam-directing device consisting of a rod with a central pivot. Favourable results were achieved, despite the fact that most of the patients had advanced carcinoma.

Female↗
PubMed1976

Microvibration: capable of inducing spontaneous contractions in smooth muscles.

Spontaneous contractions were elicited by the vibration of small amplitude (microvibration) imposed upon the quiescent strips prepared from the ureter and portal vein of dogs. An acceleration of the existing rhythm in the spontaneously contracting strips was also brought about by microvibration. Frequencies and amplitudes of microvibration ranged from 1 to 90 Hz and from 50 to 150 mum, respectively. Imposed cyclic strains were less than 1% at their maximum. Up to the amplitude of 150 mum, the greater the amplitude, the faster the induced rhythm. Stepwise increase of the frequencies up to 30 Hz brought about a gradual acceleration of rhythmicity. At frequencies of above 30 Hz, no appreciable frequency-dependent differences were observable among the responses induced. Local adrenergic mechanism proved to have nothing to do with these effects.

Animals↗