Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Heat-labile enterotoxin (LT) produced by a human strain of enterotoxigenic Escherichia coli (286C(2)) was purified to homogeneity from pH extracts of fermentor-grown cells by ultrafiltration, (NH(4))(2)SO(4) fractionation, hydrophobic chromatography on norleucine-Sepharose 4B, hydroxylapatite chromatography, and Bio-Gel P-150 filtration. Purified LT preparations exhibited biological activity comparable to that of cholera toxin in four bioassays specific for the two enterotoxins (Y-1 adrenal tumor cells, Chinese hamster ovary cells, pigeon erythrocyte lysates, and skin permeability test). The overall yield of LT protein was 20%, which represented a 500-fold purification over pH extracts. A native molecular weight of 73,000 was determined by gel electrophoresis. The toxin dissociated upon treatment with sodium dodecyl sulfate, pH 7.0, into two components with molecular weights of 44,000 and 30,000. Purified LT preparations were remarkably stable over a wide range of storage conditions, temperatures, and pH's. The biological activity was increased by incubation with trypsin and completely destroyed by pronase and proteinase K, whereas deoxyribonuclease I, ribonuclease, and phospholipase D had no effect. The amino acid composition of purified LT was quite different from that of cholera toxin. Neither carbohydrate nor lipopolysaccharide was present in purified preparations. The purification scheme appeared applicable to LT produced by other human and porcine enterotoxigenic strains, but reflected the amount of LT produced by each strain. These data show that LT and cholera toxin share many common chemical and physical properties, but must be purified by different techniques.
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PMID:Purification and chemical characterization of the heat-labile enterotoxin produced by enterotoxigenic Escherichia coli. 3 93

Crown-gall, one of the "plant cancer" is induced in the presence of a soil bacterium Agrobacterium tumefaciens which elaborates a Tumor inducing principle (T.I.P.), the nature of which is unknown. Several informations suggest that some DNA sequences of bacterial origin are included in tumorous cells of tissue cultures. A ribonuclease inhibits induction. An RNA extracted from Agrobacterium induces some hyperplasia transplantable by graft.
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PMID:[Nucleic acids during tumorous transformation in plants]. 13 Jan 89

Mouse 3T3, Simian virus 40 transformed 3T3 cells (SV3T3) and two SV3T3 lines showing reversion of their transformed phenotype (Rev 3 and Rev 5) have been studied with respect to electrophoretic mobilities and colloidal iron hydroxide (CIH) binding density visible by electron microscopy, before and after incubation with neuraminidase or ribonuclease. The results show that, in general, the marked changes in both sets of surface parameters associated with transformation are largely reversed in the Rev 5 revertant, and only partially reversed in the Rev 3 line. It was also observed that, in common with Ehrlich ascites tumor (EAT) cells examined previously, the densities of CIH-particles bound over the microvilli of all the cell types was 1.5 to 2.7 times higher than those bound to the spaces between them. In contrast to the EAT cells, the higher density of CIH particles bound over the microvilli was not due to neuraminidase-sensitive binding sites.
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PMID:Some electrical properties of the peripheries of murine 3T3 cells with respect to viral transformation and reversion. 17 59

A cross-linked dimer of pancreatic ribonuclease A (ribonucleate 3'-pyrimidino-olitonucleotidohydrolase, EC 3.1.4.22), at a 10 mg/liter concentration, blocks proliferation of tumor cells. The protein retains this ability after inactivation by iodoacetate. The cytostatic effect of ribonuclease preparations on various cell lines correlates well with their rate of uptake: for example, monomeric ribonuclease A is much less effective and is taken up into the cells 10 t0 15 times more slowly. Cell fractionation studies on hepatoma cells indicate accumulation of the dimer in the lysosomal system. Ribonuclease dimer induces a labilization of the lysosomes when added to cell homogenates, raising the possibility that its antitumoral effect may be mediated by endocytosis and lysosomes.
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PMID:Inhibition of tumor cell proliferation by dimerized ribonuclease. 17 14

To compare regulation of nucleolar function of tumors and other tissues, it was necessary to develop assays of the fidelity of ribosomal DNA readouts. For this purpose, homochromatography analyses of complete T1 ribonuclease digestion products of the in vivo labeled 45 S preribosomal RNA were compared with those of 18S and of 28 S ribosomal RNA. Homochromatography analysis of the in vitro readout product of isolated nucleoli showed the presence of many large marker nucleotides of the in vivo 45 S preribosomal RNA. Moreover, no other large oligonucleotides were detected. The in vitro readout product of nucleolar chromatin had the same T1 ribonuclease digestion products, including the large marker of oligonucleotides. However, the in vitro readout product of nucleolar DNA contained no large marker T1 ribonuclease oligonucleotides. These results indicate that the fidelity of nucleolar readouts is controlled by regulatory proteins of the nucleolar chromatin. Differences were found in nucleolar proteins of normal rat liver and Novikoff hepatoma by immunological analyses. The possibility exists that differences in readout rates of tumor and other nucleoli are related to the protein difference detected by these immunological studies.
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PMID:Homochromatographic and immunological analysis of controls of nucleolar gene function. 18 35

The ribonuclease activity of peripheral lymphocytes from Balb/c mice was studied at various intervals subsequent to infection of mice by oncornavirus. Lymphocytes from mice infected with Friend leukemia virus possessed elevation of RNase activity within 8 days subsequent to infection. Balb/c mice infected with Moloney sarcoma virus demonstrated an analogous elevation of RNase activity with 7-9 days postinfection. Diminishment of cellular RNase activity occurred in the Friend leukemia model concomitant to the occurrence of significant numbers of erythroblasts in the peripheral blood, while ribonuclease activity in lymphocytes from mice infected with Molney sarcoma virus returned to normal 1-2 weeks subsequent to host rejection of tumor. It is concluded that elevation of RNase activity within the lymphocyte represents an early event in oncogenic viral infection within these two tumor models. The possible meaning of elevation of RNase activity is a target (the lymphocyte) not predestined to undergo neoplastic transformation is discussed.
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PMID:Alteration of cellular ribonucleases associated with murine oncogenic virus infection. 20 72

The major ribonuclease of adult guinea pig epidermis has been isolated and purfied over 1000-fold by a combination of ammonium sulfate fractionation, affinity and ion-exchange chromatography, and electrophoresis. The purified enzyme is free from phosphodiesterase and phosphatase activities. The ribonuclease is optimally active near neutrality in phosphate buffer, with a Km of 3mu g/ml toward [14-C]RNA from Erhlich ascites tumor cells. (here are no metal requirements for activity. The enzyme catalyzes the endonucleolytic hydrolysis of high molecular weight yeast RNA and it also hydrolyzes polycytidylic and polyuridylic acids, but not polyadenylic, polyguanylic, and polyinosinic acids. The apparent molecular weight of the active enzyme is 28 500.
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PMID:Epidermal nucleases: purification and characterization of ribonuclease from mammalian epidermis. 23

The spontaneous decay of methyl green-pyroninophilia in Burkitt's lymphoma was studied at four temperatures (0 degrees C to 56 degrees C) in four biopsies using Kurnick's method. The decay is temperature and time related and is presumably due to intrinsic enzymatic action, probably ribonuclease. Imprints from tumor tissue preserved at 0 degrees C lose pyroninophilia by six hours; from tumor preserved at room temperature pyroninophilia, in most instances, would have been lost by three hours, from tumor tissue maintained at 37 degrees C, by two hours in most instances and by 15 minutes at 56 degrees C in most instances. The absence of pyroninophilia after these intervals at the appropriate temperatures should not detract from the diagnosis of Burkitt's Lymphoma.
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PMID:Decay of methyl green-pyroninophilia in Burkitt's lymphoma. 26 49

12-O-Tetradecanoyl-phorbol 13-acetate is a very effective tumor promotor and inflammatory agent and can act as a mitogen for a subset of T lymphocytes. We report here that even short exposure of lymphocytes to 12-O-tetradecanoyl-phorbol 13-acetate changes the balance between the levels of neutral ribonuclease and ribonuclease inhibitor. The most dramatic change occurs in a B-lymphocyte-enriched population. We find that most, if not all, of the neutral ribonuclease activity in circulating lymphocytes is associated with this population and that this activity is lost with exposure to 12-O-tetradecanoyl-phorbol 13-acetate. Both 12-O-tetradecanoyl-phorbol 13-acetate and phytohaemagglutinin increase the level of ribonuclease inhibitor in T cells. However, phytohaemagglutinin has no effect on the ribonuclease or inhibitor level of the B-cell-enriched population.
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PMID:The effect of 12-O-tetradecanoyl-phorbol 13-acetate on the ribonuclease activity of circulating human lymphocytes. 31 10

The tRNA nucleotidyltransferase activity (3H-CMP incorporation into 3'-terminus of tRNApC) in cytoplasmic fractions of various types of cells such as Ehrlich ascites tumor cells, mouse liver and spleen cells, rat spleen, lymph node, and macrophages cells was found to be dependent on the concentrations of nucleoside 5'-triphosphates (ATP, GTP, UTP, dATP, dGTP, dCTP, and/or dTTP). The purified tRNA nucleotidyltransferase did not show such dependency. The dependency of the enzyme activity on nucleoside 5'triphosphates in the crude cytoplasmic fractions was possibly due to the presence of inhibitors which interfere with the repair system of defective 3'-termini of tRNA. Two kinds of inhibitors were distinguishable in the cytoplasmic fractions. One was unstable on heat treatment at 55 decrees C and showed ribonuclease activity for the tRNA 3'-terminus. The other which lacked ribonuclease activity was rather stable to the heat treatment and inhibited purified tRNA nucleotidyltransferase. The actions of both inhibitors were suppressed by nucleoside 5'-triphosphates.
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PMID:Effect of nucleoside 5'-triphosphates on tRNA nucleotidyltransferase activity in cytoplasmic fractions of various types of mammalian cells. 42 63


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