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Biomedical subjects

H Ono

Publications and source records attributed to H Ono.

At least 739 records · Page 41Linked to original sources
PubMed1974

Effects of phentolamine on the SA node of the dog heart in situ.

Direct perfusion of the sinus node artery at constant pressure of 100 mmHg was arranged in 6 canine hearts in situ. The injection of phentolamine into the sinus node artery usually induced dose-dependent positive chronotropic effect. However, at a larger dose of 300 mug, phentolamine frequently induced a biphasic chronotropic response, i.e., sinus deceleration followed by sinus acceleration. Phentolamine at a large dose of 1 mg usually induced a negative chronotropic effect. The threshold dose for inducing sinus acceleration was about 1 to 10 mug. The positive chronotropic response to phentolamine was blocked either by propranolol or by tetrodoxin. That to norepinephrine was blocked by propranolol but not suppressed by tetrodotoxin. These results suggest that the phentolamine-induced sinus acceleration is due to catecholamine which is released by excitation of local adrenergic fibers. The sinus deceleration to higher doses of phentolamine was not blocked either by atropine or by tetrodotoxin. It suggests that phentolamine has a direct depressive effect on the SA node at extremely high dose levels.

Animals↗
PubMed1973

Genetic analysis of developmental stages of the cellular slime mold Dictyostelium purpureum.

71 Mutants of Dictyostelium purpureum, unable to carry out normal development, were isolated. These mutants fall into three phenotypic classes. The mutants of the first class do not aggregate. Those of the second class develop a little further and form conical aggregates. The mutants of the third class progress still further, and the conical aggregates are transformed into finger-shaped masses, but no fruiting bodies are formed. Mutants of each class were able to form fruiting bodies when mixed with mutants of other classes. Pairs of mutants belonging to the same class, however, never responded synergistically. This result indicates the presence of three distinct developmental stages in the process of the fruiting-body formation. Experiments with actinomycin D suggested that genes controlling the developmental process of D. purpureum were divided into three groups which were identical to those identified by the analysis of synergism.

Dactinomycin↗
PubMed1973

Screening and isolation of penicillinase inhibitor, KA-107.

It is known that penicillin resistance of bacteria is mainly caused by the inactivation of penicillin by penicillinase derived from such strains. We have developed a screening procedure for penicillinase inhibitors. Several microorganisms were found to produce such inhibitors, and from the culture filtrate of Streptomyces gedanensis ATCC 4880 a penicillinase inhibitor, named KA-107, was isolated. The characteristics of this inhibitor were revealed by an in vitro test by using penicillinase derived from penicillin resistant Staphylococcus aureus, FS-1277. When KA-107 was used in combination with penicillin-G, ampicillin, d- or l-phenethicillin, the growth inhibitory activity of these penicillins was maintained.

Anti-Bacterial Agents↗