Effect Of actinomycin-D Research Articles

Effect of actinomycin-D on bone mineral metabolism in rats.

Actinomycin-D, when given to rats, decreased the plasma calcium level, increased the retention of85Sr in the whole body and plasma but not in bone. The findings suggest that Actinomycin-D interferes with bone resorption but not with the mineralization process.

Effect of actinomycin-D on DNA synthesis in African green monkey kidney cultures uninfected and infected with SV40.

Effect of actinomycin-D on DNA synthesis in African green monkey kidney cultures uninfected and infected with SV40.

The effect of actinomycin-D on TSH formation, release and inhibition by thyroxin

Actinomycin-D, in doses known to block the metabolic effects of thyroid hormone, failed to alter the circulating TSH titer of hypothyroid rats and the rate of disappearance of TSH from the circulation in euthyroid and hypothyroid rats. It also failed to depress the marked increase in pituitary TSH content seen after thyroxin injection into hypothyroid rats. Unexpectedly, actinomycin-D alone caused an increase in pituitary TSH and inhibited the ability of thyroxin to suppress TSH secretion. Therefore, it is suggested that there may be an intrahypophyseal repressor substance which tonically limits TSH formation and is dependent upon a short-lived messenger-RNA which is blocked by actinomycin-D. Possibly this intrahypophyseal repressor is the intermediary by which thyroid hormone inhibits the pituitary. Actinomycin-D, at a concentration as low as 0.056 μg/ml, also inhibited the osmoregulatory response of thyroid slices to TSH stimulation in vitro.

The effect of actinomycin-D on chiasma frequency in Vicia faba.

The effect of Actinomycin-D was studied on chiasma frequency in Vicia faba (var. Weibull's Akerabona). A significant decrease in chiasma frequency over control was observed in all cases irrespective of the time of fixation and chemical concentration. However, the maximum decrease was found in the material fixed after a recovery period of 24 hours. The decrease in chiasma frequency showed a linear relationship with time of recovery. Besides reduction in the chiasma frequency, cells showing complete failure of homologous pairing were also observed. These findings are discussed in the light of actinomycin-D action.

Antitumor effect of actinomycin-D on transplantable Wilms tumor in rats.

Antitumor effect of actinomycin-D on transplantable Wilms tumor in rats.

Erythropoietin-induced DNA synthesis in normoblasts [formula omitted]: Effect of actinomycin-D

Erythropoietin stimulates DNA and heme synthesis by erythroblasts in vitro . Actinomycin-D completely suppresses the ESF stimulation of heme synthesis without affecting heme synthesis in control cultures. At the same concentration, AM depresses DNA synthesis in both ESF and control cultures but does not abolish the stimulation of DNA synthesis by ESF. We conclude that the ESF stimulation of DNA synthesis is not dependent on the stimulation of heme synthesis.

EFFECT OF ACTINOMYCIN-D ON PROTEIN, RIBONUCLEIC ACID, AND ENZYME FORMATION IN BACILLUS SUBTILIS

Effects of actinomycin-D on protein synthesis, RNA synthesis, and on formations of amylase, protease, alkaline phosphatase, and ribonuclease in Bacillus subtilis K were investigated.The RNA synthesis and the protein synthesis were inhibited quite similarly by actinomycin-D of various concentrations. Inhibition of the formation of amylase, protease, and alkaline phosphatase was also similar, but ribonuclease formation was quite resistant and was stimulated markedly at a lower concentration of actinomycin-D.

Effect of actinomycin-D on calcium homeostasis.

SummaryActinomycin-D produces hypocalcemia in rats 10 to 15 hours after administration. This effect can be produced in the absence of kidneys, adrenals and thyroid glands. Possible mechanisms of action are discussed.