Thirteen patients with methotrexate-resistant metastatic trophoblastic disease have been treated with actinomycin D. Complete remissions were observed in six patients, and substantial response was noted in all but two cases. On the basis of these data, actinomycin D appears to be useful in the treatment of patients with per sistent metastatic trophoblastic disease following development of resis...

Previously it has been found that in tobacco callus cells nucleolar vacuoles repeatedly form and contract. In this study, nucleolar vacuoles were investigated by using radioautography, actinomycin D, and electron microscopy . It was found, from grain counts of nucleoli labeled with uridine 3H, that nucleoli containing vacuoles had more than three times as many grains/μ2 of nucleolar substance a...

Previously it has been found that in tobacco callus cells nucleolar vacuoles repeatedly form and contract. In this study, nucleolar vacuoles were investigated by using radioautography, actinomycin D, and electron microscopy. It was found, from grain counts of nucleoli labeled with uridine-(3)H, that nucleoli containing vacuoles had more than three times as many grains/micro(2) of nucleolar subs...

Actinomycin D (AMD) at concentrations that inhibit cellular RNA synthesis by 85% or more causes an acute phase of lethal cell degeneration in HeLa cultures beginning as early as 3 hr after drug exposure, resulting in the nearly complete loss of viable cells by 12 hr. The loss of cells during this acute phase of lethality is closely dose dependent. Vero, WI38, or L cells are not susceptible to t...

Actinomycin D'-H (80,000 cpm//ug) was administered to tumor-bearing mice and the disposition of the drug determined. Radioactivity was found in all peripheral tissues examined (in cluding tumor), hut none was found in the brain. No significant metabolism of actinomvein was observed, although binding of the drug altered its extraction characteristics. Differential centrifugation of liver homogen...

Actinomycin D (or cycloheximide) administered prior to radioactive 25-hydroxycholecalciferol blocks the metabolism of 25-hydroxycholecalciferol to polar metabolites that accumulate in intestinal tissue, while it does not prevent the 25-hydroxylation of vitamin D(3) in the liver. Actinomycin D given after radioactive 25-hydroxycholecalciferol does not inhibit 25-hydroxycholecalciferol metabolism...

Polsinelli, M. (University of Pavia, Pavia, Italy), O. Ciferri, G. Cassani, and A. Albertini. Mechanism of resistance to actinomycin in Bacillus subtilis. J. Bacteriol. 88:1567-1572. 1964.-Strains of Bacillus subtilis were rendered resistant to actinomycin D by serial transfer in increasing concentrations of the drug. Resistance to the antibiotic appeared to be due to an altered cell-wall perme...