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At least 1,441 records · Page 80Linked to original sources
PubMed1977

E1On the effect of 6-methyluracil on mice damaged by 2,4,6-triethylene-imino-1,3,5-triazine or by X-irradiation (author's transl).

Survival time of mice after i.v. injections of 2,4.6-triethylene-imino-1,3,5-trazine (TEM) or total body-X-irradiation (TBI) was increased by 6-methyluraclil (6-MU) when given in food (200 ppm). Under the same conditions, 6-MU decreased the involution of spleen and thymus (as measured by DNA-content and DNase II activity) under the infuence of TEM and enhanced the regeneration of the spleen after TBI. Elevation of DNase I- and protein content of the kidneys and a (short-dated) increase of incorporation of 14C-phenylalamine into microsomes of liver of 14C-orotic acid into RNA of liver and kidney suggest that the influence of 6-MU is mediated at least partly by a specfically anabolic effect.

Animals↗
PubMedDate not supplied

[Ultrastructural changes in hepatocyte nuclei reflecting genome expression and nuclear RNA biosynthesis in the early premitotic period of rat liver regeneration].

Modifications of the nucleus ultrastructure and specific radioactivity of nuclear and cytoplasmic RNA from hepatocytes were studied at early stages of liver regeneration using 14C-orotic acid as a labelled precursor. It is shown that the first three hours after partial hepatectomy are characterized by mobilization of inherent abilities of the nucleus and initiation of chromatin activation. Then three hours after operation the activity of nucleolar and extranucleolar apparatus increases. By 12 hours chromatin associates with a nuclear membrane for preparing DNA replication.

Animals↗
PubMed1982

Cytotoxicity of a new uridine analog, 4-hydroxy-1-(beta-D-ribofuranosyl)-pyridazine-6-one, and its interaction with uridine kinase.

A new uridine analog, 4-hydroxy-1-(beta-D-ribonfuranosyl)-pyridazin-6-one (3-deaza-6-azaUrd), inhibited the growth of L1210 cells in culture, with a concentration to reduce growth rate to 50% of control of 7 X 10(-5) M. After treatment for 24 or 48 h with 5 X 10(-4) M 3-deaza-6-azaUrd, 80% of the cells were unable to resume growth when the analog was removed from the cultures; also, 99% of the cells were killed, as determined by colony formation in soft agar. Studies on the prevention of the cytotoxic effects of 5 X 10(-4) M 3-deaza-6-azaUrd showed that uridine or cytidine gave complete protection. 2'-Deoxycytidine also gave partial protection, but orotic acid or thymidine had no effect on the growth inhibition by 3-deaza-6-azaUrd. These results suggested that growth inhibition by 3-deaza-6-azaUrd might be due to interference in pyrimidine biosynthesis. Activation of 3-deaza-6-azaUrd to its 5'-phosphate derivative appeared to be catalyzed by uridine kinase. 3-Deaza-6-azaUrd was shown to complete with uridine for phosphorylation (Ki = 4.7 mM) and, therefore, to be a possible alternative substrate for uridine kinase from mouse kidney (Km for uridine = 82 microM). The enzyme was partially purified by streptomycin sulfate precipitation, ammonium sulfate fractionation, and gel filtration. This preparation was found to be free of pyrimidine nucleoside phosphorylase and uridine monophosphate kinase.

Animals↗
PubMedDate not supplied

[Use of biochemical indices in the classification of Sporozoa].

The paper presents a survey of literary and author's own data on metabolism of nitric bases, nucleosides and orotic acid in Eimeria, Toxoplasma and Plasmodium. Experimental data on nucleotide content of DNA, fractional content of ribosome RNA, isofermental spectrum of a number of oxidation-reduction enzymes and immunochemical analysis of antigens in various groups of Sporozoa (Eimeria, Toxoplasma and Plasmodium) are given. A possible use of biochemical and immunochemical data for the taxonomy of Sporozoa is suggested.

Animals↗
PubMed1983

Pyrimidine metabolism in Tritrichomonas foetus.

The pyrimidine metabolism of Tritrichomonas foetus (KV 1) was studied using whole cells and cell homogenates. Pyrimidines and pyrimidine nucleosides were readily incorporated into nucleic acids. Orotate and aspartate were not incorporated into pyrimidine bases. Enzymes of the pyrimidine salvage pathway (i.e., thymidine and uridine phosphorylases and uridine kinase) were detected in trophozoite homogenates, but the activities of de novo pyrimidine synthesis enzymes (i.e., carbamoylphosphate synthase, aspartate transcarbamoylase, dihydroorotase and dihydroorotate dehydrogenase) were below the level of detection in these same homogenates. The evidence presented supports the proposal that T. foetus is incapable of synthesizing pyrimidines de novo but is capable of salvaging preformed pyrimidines and pyrimidine nucleosides from the growth medium and that enzymes of this parasite's pyrimidine salvage pathway are not organelle-associated.

Animals↗
PubMedDate not supplied

[Effect of acetylcholine on incorporation of 14C-precursors into uridylic and cytidylic nucleotides of the RNA of digestive glands].

The incorporation rate of [2-14C]orotic acid and [2-14C]uridine into the cytidylic RNA nucleotides is significantly lower than into the uridylic ones. In the liver it was twice as low as in the stomach mucosa or in pancreas of albino rats. The administration of acetylcholine in combination with proserine has no influence on the RNA content and its nucleotide composition in the tissues. The administered drugs however caused changes in the relation of the incorporation rates of both labels into uridylic and cytidylic RNA nucleotides, which evidences for the uridylic nucleotide synthesis. In the liver such changes are not detected, but utilization of the labeled uridine is shown to be more intensive for the cytidylic RNA nucleotides synthesis.

Acetylcholine↗
PubMedDate not supplied

[Estradiol reception and induction of DNA-dependent RNA synthesis and adaptive enzymes in the mammary glands of mice].

The content of estradiol receptors in the mammary glands of virgin female mice, and the capacity of this hormone to induce RNA synthesis, hexokinase, pyruvatkinase, and glucose-6-phosphoric dehydrogenase in the glands was studied. H3-estradiol binding to the mammary glands was found to be highly specific: only estradiol, and, to a lesser degree, estron, competed with H2-estradiol for the binding sites, while progesterone and hydrocortisone failed to affect the binding of H3-estradiol. As determined by the method of exchange of the receptor-bound endogenous hormone for the labeled exogenous one, the value of H3-estradiol specific binding was 4.3+/-1.5 10(-15) M/mg protein. Under the influence of estradiol the incorporation of H3-adenine and H3-orotic acid into the RNA of the mammary glands increased by 70%, and activity of the enzymes under study was almost doubled.

Animals↗
PubMed1983

[Lysinuric protein intolerance].

We report the first case of lysinuric protein intolerance observed in Germany. A girl of Turkish ancestry suffered from severe dehydration at the age of 6 months after changing from breast milk to cow milk. Because of a microcytic hypochromic anaemia and erythrophagocytosis in the bone marrow a hematologic disease (Farquar's disease) was suspected. The definite diagnosis of lysinuric protein intolerance was eventually clarified by the following laboratory and clinical data: increased urinary excretion and low plasma concentration of lysine, arginine and ornithine, apathy, vomiting, diarrhea and hyperammonemia after an oral protein load, high serum LDH-activity, ferritinemia, and increased urinary excretion of orotic acid. Under therapy with citrullin and a low-protein diet the metabolic situation remained stable, even during infections. The bone marrow findings have been reported only in one further case of lysinuric protein intolerance.

Amino Acid Metabolism, Inborn Errors↗
PubMed1981

Analysis of loss of nuclear RNA in azo dye-induced hepatoma by DNA-RNA competitive hybridization.

DNA-RNA hybridization studies, using nuclear RNA's (nRNA's) labeled in vivo and in vitro with high specific radioactivities, were performed to compare the nRNA populations of normal rat liver, livers treated with 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB), and 3'-Me-DAB-induced hepatomas. The study with normal liver nRNA labeled by i.p. injection of [3H]orotic acid indicated that the nuclei of a 3'-Me-DAB-induced transplanted hepatoma, AH136B, lacked some RNA species present in normal liver nuclei. No qualitative difference in thee RNA populations was seen between normal liver and the livers of rats fed a carcinogenic amount of 3'-Me-DAB, either alone or in combination with 4-nitrostilbene which enhanced the azo dye carcinogenesis. Then, nRNA's of both normal liver and AH136B hepatoma were labeled in vitro by phosphorylation with polynucleotide kinase and adenosine 5'-[gamma-32P]triphosphate. The competitive hybridization with 32P-labeled normal liver nRNA was competed, and the deletion of RNA in the nuclei of AH136B hepatoma or 3'-Me-DAB-induced primary hepatoma was estimated to be 15% or more in the measure of radioactivity of the hybridized normal liver nRNA. 32P-labeled AH136B hepatoma nRNA was completed completely by liver nRNA's, suggesting that no unique RNA species were present in the hepatoma nuclei.

Animals↗
PubMed1982

[Neonatal hyperammonemia due to ornithine transcarbamylase deficiency (author's transl)].

The clinical and biochemical findings in a patient with the inherited disease so called hyperammonemia type II are presented. The patient was a male who had the first abnormal symptoms of tremors and continuous crying at 35 hours of age and exhibited a rapid clinical course dying 62 hours after birth. Rejection of food, respiratory problems, hypotonia and tonic-clonic convulsions were other outstanding clinical symptoms observed. Withdrawal of the feedings and initiation of a perfusion did not improve the clinical picture. Biochemical studies in samples of blood, urine and CSF revealed the presence of high concentrations of ammonia, alanine, glutamine and orotic acid. Final diagnosis was achieved when post mortem liver ornithine transcarbamylase activity was found to be lower than 6% with respect to that of adequate controls. Carbamyl phosphate synthetase, another urea cycle enzyme measured, was within normal limits of activity.

Amino Acid Metabolism, Inborn Errors↗
PubMed1978

Comparison of the effect of drugs on Babesia in vitro and in vivo.

It was previously shown that Babesia-infected blood maintained in vitro incorporated high levels of 3H hypoxanthine and that the uptake could be suppressed by babesicidal drugs. In the current paper the hypoxanthine pathway was shown to be the most sensitive in testing such drugs for activity in vitro. Other pathways involving orotic acid, glutamine or thymidine were less sensitive. The highest counts were achieved when 3H hypoxanthine was added 1 h after cultures were set up. Drugs which had previously shown activity against Babesia in vitro were added to cultures of B rodhaini and after 24 h incubation parasitised cells were inoculated into groups of mice. Known babesicidal drugs suppressed or delayed infection in mice and 3H hypoxanthine analogues also showed some activity. These analogues, however, showed no therapeutic properties when injected into B rodhaini infected mice.

Animals↗