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Biomedical subjects

K Tsuchiya

Publications and source records attributed to K Tsuchiya.

At least 703 records · Page 39Linked to original sources
PubMed1975

Electrical and mechanical activities of longitudinal muscle contraction elicited by transmural electric stimulation.

Intracellular electrical and mechanical activities were simultaneously recorded from the longitudinal muscle of isolated guinea-pig jejunum when the preparation was stimulated transmurally by square pulses of 1 msec, 10 Hz, 10-40 V. Transmural stimulation of more than 30 V induced co-ordinated peristaltic waves under intraluminal pressure at levels subthreshold for the peristaltic reflex. Transmural stimulation of less than 30 V induced various types of mechanical responses. After termination of stimulation, rebound excitation was observed. Electrical activities of the longitudinal muscle were compared with various mechanical responses. Slow depolarization without spike potential was recorded when the longitudinal muscle contracted without circular muscle contraction. However, spike potential was recorded from the longitudinal muscle when circular muscle contraction was present as a response. Hyperpolarization was observed soon after the beginning of stimulation. This hyperpolarization was persistent to atropine at 10(-6) g/ml. These electrical and mechanical responses to transmural stimulation disappeared when the preparation was treated with tetrodotoxin at 2 X 10(-7) g/ml.

Animals↗
PubMed1973

Chemical modification of maridomycin, a new macrolide antibiotic.

Maridomycin, a new macrolide antibiotic, and tetrahydromaridomycin were acylated into their mono, di, and tri acyl derivatives. These derivatives were compared with the parent antibiotic, maridomycin, for their (i) in vitro antimicrobial activities, (ii) protective effect in mice infected with Staphylococcus aureus (oral administration), (iii) blood levels attained in rats, and (iv) acute toxicity in mice (intraperitoneal administration). All the derivatives showed either the same or less activity in vitro, but 9-acyl, 9, 2'-diacylmaridomycin and 9, 13, 2'-triacetyltetrahydromaridomycin demonstrated improved therapeutic effects together with higher blood levels and low toxicity. 9-Propionylmaridomycin showed the most favorable biological properties.

Acylation↗