[The effect of 211At labelled monoclonal antibody against gastric cancer on DNA, RNA and protein synthesis in gastric cancer cell].
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By means of nuclide precursor incorporation, the effects of 211At labelled monoclonal antibody against gastric cancer (211At-3H11McAb) on DNA, RNA and protein synthesis in gastric cancer cell were studied. The results show that 211At-3H11McAb and Na211At-3 inhibit 3H-TdR, 3H-UR and 3H-Leu incorporation, especially 3H-UR incorporation, into gastric cancer cell at 3.7 x 10(4)Bq and 1.85 x 10(5)Bq; the inhibiting rates depend on concentration. The DNA biosynthesis in gastric cancer cell gradually recover after the drug is removed, suggesting that the drug should exert an inhibiting action on DNA biosynthesis in tumor cell through interference of DNA metabolism.Cite
L1210 cells
Phototoxicity
Methoxsalen
Ultraviolet light
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Cytembena, at low concentrations, caused an inhibition of the in vitro growth of L1210 mouse leukaemia cells which could not be reversed by reduced folates, purines, amino acids or deoxyribonucleosides. Invitro experiments with a number of enzymes of folate metabolism produced no evidence that this drug acts as an anti-folate in mammalian tumor colls. However, Cytembena, in therapeutic doses, caused a rapid and extensive inhibition of DNA biosynthesis. There was no inhibition of RNA biosynthesis, but at high doses some inhibition of protein biosynthesis was observed. Deoxyribonucleoside triphosphates accumulated in the presence of Cytembena, suggesting that the inhibition of DNA biosynthesis was at the polymerization stage. However, in vitro experiments failed to demonstrate any direct interaction of Cytmebena with either DNA or DNA polymerase.
Deoxyribonucleosides
Deoxyribonucleosides
Purine metabolism
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Ultraviolet light
Doubling time
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Amino acids that were utilized as sole sources of carbon and nitrogen for growth of Serratia marcescens Nima resulted in biosynthesis of prodigiosin in non-proliferating bacteria. Addition of alanine, proline, or histidine to non-proliferating cells incubated at 27 C increased the rate of protein synthesis and also caused biosynthesis of prodigiosin. No increase in the rate of protein synthesis was observed upon the addition of amino acids that did not stimulate prodigiosin biosynthesis. Increased rates of synthesis of ribonucleic acid (RNA) and of deoxyribonucleic acid (DNA) (a small amount) also occurred after addition of amino acids that resulted in biosynthesis of prodigiosin. After incubation of 24 h, the total amount of protein in suspensions of bacteria to which alanine or proline was added increased 67 and 98%, respectively. Total amounts of DNA and of RNA also increased before synthesis of prodigiosin. The amounts of these macromolecules did not increase after addition of amino acids that did not induce biosynthesis of progidiosin. However, macromolecular synthesis was not related only to prodigiosin biosynthesis because the rates of DNA, RNA, and protein synthesis also increased in suspensions of bacteria incubated with proline at 39 C, at which temperature no prodigiosin was synthesized. The quantities of DNA, RNA, and protein synthesized were lower in non-proliferating cells than in growing cells. The data indicated that amino acids causing biosynthesis of prodigiosin in non-proliferating cells must be metabolized and serve as sources of carbon and of nitrogen for synthesis of macromolecules and intermediates. Prodigiosin was synthesized secondarily to these primary metabolic events.
Prodigiosin
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The effect of the new antibiotic, myxin, on the syntheses of deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and protein in Escherichia coli (strains B and 15T − ) was examined. Within 7 min of the addition of myxin at 5 μg/ml, the synthesis of new bacterial DNA was almost completely inhibited. This was followed by an extensive degradation of the pre-existing DNA to an acid-soluble form. All of the evidence indicated that the primary effect of the antibiotic was on cellular DNA. The synthesis of RNA was completely inhibited after 15 min of exposure to myxin (5 μg/ml), and the synthesis of protein was markedly reduced after 30 min. There was no measurable breakdown of either RNA or protein in the myxin-treated cells. A marked stimulation of 14 C-uracil incorporation was found in the presence of myxin in 15T − cells only. This did not result from an increased rate of RNA synthesis but was due to an increase in the proportion of exogenous uracil, relative to endogenous uracil, incorporated into cellular RNA. This probably reflected a partial inhibition of the biosynthesis of uridine monophosphate from orotate. At 4.5 μg of myxin per ml and with 0.8 × 10 8 cells per ml, 50% of the antibiotic was reduced in 15 min from the biologically active oxidized form to the biologically inactive state. Under these conditions, a maximum of 0.6% (27 μμg/ml) of the myxin was retained in the cells.
Uracil
Orotic acid
Thymidine
Mode of Action
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The plant alkaloid thalicarpine inhibits the synthesis of DNA, RNA, and protein in cultured L1210 cells. Significant inhibition of thymidine incorporation into L1210 DNA and uridine into RNA by 100 µm thalicarpine occurs within 20 min. Whereas inhibition of DNA synthesis is only partially reversible, that of RNA is nearly reversed when the cells are washed free of the drug. Thalicarpine also inhibits early steps of nucleotide triphosphate biosynthesis.
DNA from L1210 cells inhibited by thalicarpine sediments along with the bulk DNA from uninhibited cells whereas the RNA from inhibited cells is deficient in all species of RNA and in particular, rapidly labeled, heterogenously sedimenting RNA. Inhibition of protein synthesis by thalicarpine probably occurs at some early phase of its biosynthetic scheme. Thalicarpine is notable for its multiple and diverse modes of action, all or part of which may be responsible for its chemotherapeutic effect.
L1210 cells
Thymidine
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Bovine GH and two fragments which were obtained by dissociation of a limited tryptic digest of the hormone stimulated protein, RNA, and DNA synthesis of contact-inhibited human fibroblasts. The stimulation of protein, RNA, and DNA synthesis was similar for the test substances. Maximal stimulation was noted at 10 nM. At that concentration, protein, RNA, and DNA synthesis were respectively increased 1.80, 1.42, and 1.37 times by GH; 1.93, 1.27, and 1.46 times by A-I (the larger fragment); and 1.99, 1.26, and 1.33 times by A-II (the smaller fragment). The action of GH, A-I, and A-II was similar to that of fetal calf serum, but was distinguished by the time course of stimulation and by the magnitude of the response. For example, GH, A-I, and A-II produced their earliest detectable effect at 10 h for protein synthesis, 22 h for RNA synthesis, and 26 h for DNA synthesis. On the other hand, serum stimulated protein, RNA, and DNA synthesis at 6, 10, and 16 h, respectively. These data show that human fibroblasts respond equally to GH, A-I, and A-II and suggest that there may be more than one "active site" in the GH molecule. Lastly, human fibroblasts may represent a useful system to study the actions of GH in vitro. (Endocrinology102: 1756, 1978)
Bovine somatotropin
Somatropin
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The effects of concentrations of 2-phenoxyethanol of negligible bactericidal activity upon the rates of biosynthetic assimilation by Escherichia coli, of 14C-thymidine, 14C-uracil, 14C-phenylalanine and 14C-glucose, were assessed. Increasing the drug concentration from 0.05-0.4% w/v progressively increased inhibition of growth rate, measured as changes in optical density. Thymidine, uracil and glucose assimilation were inhibited to an extent similar to growth rate, whilst phenylalanine incorporation was markedly less sensitive at the lower concentrations (leads to 0.2% w/v). In addition to its previously observed roles in inhibiting oxidative phosphorylation and TCA cycle enzymes, it is suggested that 2-phenoxyethanol can exert a more direct inhibitory action upon DNA and RNA biosynthesis and possibly on protein biosynthesis.
Uracil
Thymidine
Assimilation (phonology)
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Abstract Single injections of 100 μg of 5‐fluorouracil (5‐FU) containing 1.25 μc of [2‐ 14 C]5‐FU were made into the yolk sac of 4‐day chick embryos. Greater amounts of label were incorporated into DNA than into RNA extracts. The rate of accumulation of protein per embryo was lowered by 5‐FU to a somewhat greater extent than was either DNA or RNA. Chromatography of TCA‐soluble fraction from 5‐day embryos indicated presence of 5‐FU and two peaks of unidentified heavier molecules derived from 5‐FU. Thus the selective depression of protein accumulation and the progressive labeling of DNA from 5‐FU indicate a wider spectrum of metabolic effects in chick embryos than might be expected from the reports of 5‐FU in the literature. These data suggest that 5‐FU may act as a teratogen by one or more routes other than as an analogue of an RNA precursor.
Yolk
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