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Biomedical subjects

K Nagami

Publications and source records attributed to K Nagami.

33 records · Page 2Linked to original sources
PubMed1978

Inhibition of DNA synthesis by griseolutein in Escherichia coli through a possible interaction at the cell surface.

Griseolutein acts as a bactericidal agent, its toxicity decreasing with increase in cell density. There is no evidence that griseolutein acts at a specific stage of cell cycle. Inhibition of incorporation of radioactive thymidine into acid-insoluble fraction of cells is marked and rapid, while inhibition of incorporation of uridine also takes place. Incorporation of 32Pi into the acid-insoluble fraction of cells is inhibited while the incorporation into the nucleotide pool is not. Concentration of any of the four deoxyribonucleoside triphosphates in griseolutein-treated cells are similar to or higher than those in untreated cells. No extensive degradation of cellualr DNA is caused by griseolutein. DNA synthesis in plasmolyzed cells in not inhibited by griseolutein.

Anti-Bacterial Agents↗
PubMedDate not supplied

In vitro cytotoxicity test for estimating non-ocular irritation dose of ophthalmic solutions.

The in vitro cytotoxicity test for estimating the non-ocular irritation dose of ophthalmic solutions was investigated. In the in vitro test, normal human epidermal keratinocytes (NHEK) in a confluent monolayer were incubated for 48 hr in a medium with test compounds. The concentration of a test compound which causes a 50% reduction in NHEK viability was determined as IC50 by MTT colorimetric assay. For comparison, the in vivo rabbit ocular irritation tests were carried out by the standard Draize method. The maximum concentration, which did not show any ocular irritation, was determined as DS0. The results showed the correlation coefficient between the IC50 values and the DS0 values for 19 test compounds to be 0.82. However, the correlation coefficients for 10 compounds, which have IC50 values of less than 300 micrograms/ml, and for 7 alcohols were 0.99. The IC50-DS0 correlation curves obtained could be utilized as the critical concentrations for ocular irritation. These results suggest that our in vitro/in vivo test can estimate non-ocular irritation dose of the ophthalmic preparations in advance of the in vivo tests.

Animals↗
PubMedDate not supplied

Beta-blockade prevents ventricular failure following aortic regurgitation in rabbits.

This study investigated the effects of chronic beta-blockade on the pathophysiology of heart failure following induction of aortic regurgitation (AR). Nine rabbits with AR were administered propranolol continuously for 7 days (AR+P), 8 rabbits with AR received vehicle for the same period (AR+C), and 7 rabbits underwent sham operation. Cardiac output was lower and the left-ventricular end-diastolic pressure was higher in AR+C than in sham-operated rabbits, but there was no difference in the right-ventricular end-diastolic pressure between the two groups. Down-regulation of beta-adrenoceptors was observed in the left ventricle, but not in the right ventricle. All of these variables were reversed in AR+P. In left-ventricular failure produced by AR, (1) the augmentation of adrenergic drive occurred selectively in the left ventricle, and (2) propranolol blunted adrenergic drive and played a protective role against myocardial damage.

Adrenergic beta-Antagonists↗