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Biomedical subjects

J Hradec

Publications and source records attributed to J Hradec.

149 records · Page 9Linked to original sources
PubMed1967

Effect of some polycyclic aromatic hydrocarbons on protein synthesis in vitro.

1. The effect of the strongly carcinogenic polycyclic aromatic hydrocarbons benzo[a]pyrene, 3-methylcholanthrene and dibenz[a,h]anthracene and of the non-carcinogenic anthracene, pyrene and phenanthrene on protein synthesis was studied in vitro with subcellular systems from rat liver. 2. Both types of hydrocarbons affect amino acid activation and inhibit transfer of labelled amino acids from transfer RNA to ribosomes. 3. Only the carcinogenic compounds stimulate the incorporation of labelled algal-protein hydrolysate and of some individual amino acids into transfer RNA. The most active dose was 10mmug. under the conditions used. This effect is abolished by preincubation of pH5 enzymes with the carcinogens before the addition of radioactive amino acids. 4. The carcinogens stimulate the incorporation of some amino acids into ribosomal protein whereas the non-carcinogenic compounds have no such effects. 5. Polynucleotide-dependent stimulation of protein synthesis is greatly enhanced in the presence of the carcinogenic hydrocarbons when either free amino acids or transfer RNA charged with labelled amino acids are used. The non-carcinogenic compounds induce a partial inhibition of this process. 6. It is concluded, in agreement with other authors, that carcinogens may increase the number of active incorporation sites on both transfer and ribosomal RNA. Possible mechanisms of such an effect are discussed.

Amino Acids↗
PubMedDate not supplied

Alterations of phosphatidylcholine concentrations in the serum of patients with mammary cancer.

As determined by reversed-phase liquid-solid extraction, concentration of total phosphatidylcholines in the serum of 53 patients with mammary cancer was significantly (P<0.003) increased to 2.24 +/- 0.59 mg/ml when compared with the normal value of 1.86 +/- 0.36 mg/ml. In 31 fractions of their individual molecular species separated by high-performance liquid chromatography there was a shift to compounds composed of longer fatty acids that were significantly more abundant than in normal serum. The concentration of fractions containing stearic, oleic, linoleic, eicosatrienoic, arachidonic and docosahexaenoic acid as well as traces of C17 acids was 2-5 fold enhanced. On the other hand, molecular species containing palmitic acid combined with palmitoleic, oleic linoleic, arachidonic and further poly-unsaturated fatty acids are considerably decreased in cancer serum. All these atypical phosphatidylcholines are apparently specific products of tumor cells and are released into the blood stream. The possibility of using these alterations of phospholipid metabolism for the follow-up of cancer patients is further investigated.

Breast Neoplasms↗