Influence of progesterone on protein and RNA synthesis in cultured chick embryo liver cells

Summary Chick embryo liver primary cultures, when added with progesterone, exhibit, in comparison with the controls, a normal growth, a decline of both³H-uridine uptake and incorporation into total RNA, a decline of³H-leucine and¹⁴C serine incorporation into the proteins. Progesterone is not able to stimulate phosvitin synthesis induction.These studies were supported in part by the Italian CNR grants.     

Decreased serum responsiveness by primary monolayer cultures of preneoplastic and neoplastic mammary epithelial cells

Monolayer cultures of normal, preneoplastic and neoplastic murine mammary epithelial cells were exposed to various types of mammalian serum. A progressive decline in levels of thymidine incorporation together with a change in the ordering of sera which stimulates optimal incorporation was observed in the transformed cells.     

A differential effect of L-serine on the incorporation of 3H-deoxycytidine and 3H-thymidine into DNA of rat thymocytes.

The addition of L-serine to short-term cultures of rat thymocytes stimulated the incorporation of 3H-deoxycytidine into DNA, but simultaneously depressed the incorporation of 3H-thymidine into DNA.     

Serum cholinesterase: function in lipoprotein metabolism.

Human serum beta-lipoproteins, isolated by percipitation with heparin-calcium mixture, showed cholinesterase activity. The enzyme activity was almost proportional to the lipoprotein concentration. Rats, treated with neostigmine, a cholinesterase inhibitor, showed a significant decrease in serum beta-lipoprotein and in the incorporation of H3-lysine into the lipoprotein compared to untreated controls. The decreased incorporation of H3-lysine into beta-lipoprotein was associated with increased labelling of alpha-lopoprotein. There was no significant difference in the labelling of pre-beta-lipoprotein. We propose that LDL is formed from VLDL in the presence of cholinesterase.     

A differential effect of L-serine on the incorporation of3H-deoxycytidine and3H-thymidine into DNA of rat thymocytes

Summary The addition of L-serine to short-term cultures of rat thymocytes stimulated the incorporation of³H-deoxycytidine into DNA, but simultaneously depressed the incorporation of³H-thymidine into DNA.This investigation was supported by NIH grants No. CA-10291 and T12CA8021 from the National Cancer Institute.     

Aufnahme von thymidin durch mastocytomzellenin vitro unter der einwirkung von podophyllumstoffen

Summary SP-G and SP-I, two podophyllum preparations with spindle poison activity, were tested for their effect on³H-thymidine incorporation into P-815 mastocytoma cellsin vitro. Concentrations which inhibited cell multiplication completely did not affect DNA-synthesis as measured by thymidine incorporation.     

Time-dependence of estradiol effects on protein synthesis in the rat neurohypophysis.

The incorporation of 3H-leucine into neurohypophyseal proteins was measured in vitro, 24 h after the administration of a single dose of estradiol (0.3 mug) to castrated female rats. Estradiol treatment caused a significant increase of 3H-leucine incorporation into proteins of the posterior lobe. The effects of estradiol depended largely upon time injection. Rats injected at 06.00 h, i.e., at the end of the dark period exhibited a 74% increase in protein synthesis, whereas rat injected at 14.00 h, i.e., at the middle of the light period only showed a 30% of increase.     

Serum cholinesterase: Function in lipoprotein metabolism

Summary Human serum beta-lipoproteins, isolated by percipitation with heparin-calcium mixture, showed cholinesterase activity. The enzyme activity was almost proportional to the lipoprotein concentration. Rats, treated with neostigmine, a cholinesterase inhibitor, showed a significant decrease in serum beta-lipoprotein and in the incorporation of H³-lysine into the lipoprotein compared to untreated controls. The decreased incorporation of H³-lysine into beta-lipoprotein was associated with increased labelling of alpha-lipoprotein. There was no significant difference in the labelling of pre-beta-lipoprotein. We propose that LDL is formed from VLDL in the presence of cholinesterase.We thank Dr C. J. Hutton for helpful discussions, Miss Patricia Fontaine for technical assistance, and Miss Patricia Candow and Mrs Barbara English for secretarial work. Supported by the Canadian Heart Foundation.     

Influence of cyclic nucleotides on protein synthesis in vascular smooth muscle.

The incorporation of leucine-14C into protein in bovine mesenteric arteries was augmented by cyclic GMP (10-3 M) and decreased by cyclic AMP (10-3 M). There was no effect of 5'AMP (10-3 M). The phosphodiesterase inhibiting drugs theophylline (10-3 M) and papaverine (5 x 10-5 g/ml) both decreased the leucine-14C incorporation.     

Effect of sodium octanoate on leucine incorporation into protein of rat liver slices and of Yoshida ascites hepatoma cells.

7.38 X 10(-4) M octanoate does not significantly modify leucine incorporation into protein of rat liver slices, while in hepatoma cells a 19% inhibition has been noted. 3.69 x 10(-3) M octanoate reduces leucine incorporation to about the same extent (71-76%) in both liver slices and hepatoma cells.     

Relationship between DNA and cholesterol synthesis in kidney after refeeding

Summary DNA and cholesterol synthesis were investigated in the kidneys of fasted-refed rats. Refeeding resulted in an increase in kidney DNA synthesis, as measured by³H-thymidine incorporation, starting at 72 h. The increase in DNA synthesis was accompanied by a stimulation of cholesterol synthesis, as measured by¹⁴C-acetate incorporation into cholesterol.     

Effects of butyrate and insulin and their interaction on the DNA synthesis of rumen epithelial cells in culture

Rumen epithelial cells (REC) were incubated in the presence of various concentrations of butyrate or insulin or with both of them, to obtain information on their effect on the DNA synthesis of cultured cells. The 24-h values of 3H-thymidine incorporation into cellular DNA were measured in the presence of butyrate, insulin or butyrate plus insulin. While butyrate reduced DNA synthesis, insulin produced an increase over the control. Combined butyrate plus insulin treatment influenced the incorporation of label in accordance with the relative proportion of these two substances.     

Effects of butyrate and insulin and their interaction on the DNA synthesis of rumen epithelial cells in culture

Summary Rumen epithelial cells (REC) were incubated in the presence of various concentrations of butyrate or insulin or with both of them, to obtain information on their effect on the DNA synthesis of cultured cells. The 24-h values of³H-thymidine incorporation into cellular DNA were measured in the presence of butyrate, insulin or butyrate plus insulin. While butyrate reduced DNA synthesis, insulin produced an increase over the control. Combined butyrate plus insulin treatment influenced the incorporation of label in accordance with the relative proportion of these two substances.     

Effect of sodium octanoate on leucine incorporation into protein of rat liver slices and of Yoshida ascites hepatoma cells

Summary 7.38×10^–4 M octanoate does not significantly modify leucine incorporation into protein of rat liver slices, while in hepatoma cells a 19% inhibition has been noted.3.69×10^–3 M octanoate reduces leucine incorporation to about the same extent (71–76%) in both liver slices and hepatoma cells.     

Etude autoradiographique de l'incorporation de la thymidine-3H,de l'uridine-3H et de la phénylalanine-3H dans les chloroplastes deClivia miniata etBilbergia sp.

Summary Mature chloroplasts ofClivia miniata etBilbergia sp. show the intensive incorporation of thymidine³H into DNA and uridine³H into RNA. On the contrary, phenylalanine³H is mostly incorporated in the proplastids.     

Metabolic pathways of delta-aminolaevulinic acid in Rhodopseudomonas spheroides.

Incorporation of delta-aminolaevulinic acid 5 14C and 4 14C into the inosine monophosphate pool and into porphyrins, was studied in cell suspensions of R. spheroides. The results contradict a direct incorporation of delta-aminolaevulinic acid into the purine ring of nucleotides through gammadelta-dioxovaleric acid. It would suggest a nonspecific incorporation after degradation of delta-aminolaevulinic acid without a transamination as a first reaction.     

35S-sulphate incorporation into myelin sulphated mucopolysaccharides during rat brain development.

Rat brain myelin acid mucopolysaccharides (AMPS) incorporate 15%, 8%, 5.5% and 4% of total associated 35S-sulphate, 14, 21, 30 and 75 days after birth, respectively. The course of 35S-sulphate incorporation into total rat brain mucopolysaccharides, as well in those from myelin, had a similar feature with peak on the 2nd week and a significant decrease on the 3rd and 4th week postnatally.     

Kinetics of DNA repair synthesis in guinea-pig pancreatic slices following in vitro exposure to N-methyl-N-nitrosourethane

Summary In vitro exposure of guinea-pig pancreatic slices to NMUT resulted in an increase in hydroxyurea-insensitive³H-TdR incorporation into DNA; this represents DNA repair synthesis following NMUT-induced DNA damage. The kinetics of this hydroxyurea-insensitive³H-TdR incorporation suggest that the NMUT-induced DNA damage is largely repaired within 2 hours.Environmental Health Programs, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106 (USA). These studies were supported by National Cancer Institute (Bethesda, Md., USA). Contract No. N01-CP-23284. Technical assistance of MS.Mary Majdan is gratefully acknowledged.     

Number of glucocorticoid receptors in lymphocytes and their sensitivity to hormone action

The study demonstrated a decreased level of glucocorticoid receptors (GR) in peripheral blood lymphocytes from hypercholesterolemic subjects, and an elevated level in patients with acute myocardial infarction. In the lymphocytes with a high GR number, dexamethasone inhibited [3H]-thymidine and [3H]-acetate incorporation into DNA and cholesterol, respectively, in the same manner as in the control cells. On the other hand, a decreased GR number resulted in a less efficient dexamethasone inhibition of the incorporation of labeled compounds. These data showed that the sensitivity of lymphocytes to glucocorticoids changed only with a decrease of GR level.     

Early effect of estradiol on ultrastructure of chromatin in the endometrium and hormone-dependent mammary tumors]

After in vivo and in vitro administration of aestradiol, the chromatin of lamb endometrium and of hormone-dependent 7,12-dimethylbenzanthracene Rat mammary tumors is rapidly transformed from a condensed into a diffuse chromatin. A stimulation of 3H leucine incorporation into protein was also observed. These modifications were specific for estrogen receptor ligands and for estrogen responsive tissues. In vitro tamoxifen induced pycnosis. These changes could be used to improve the prediction of hormone dependency of human breast and uterine cancers.