Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0679427 (myeloblastosis)
 982 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mechanism of the effect of an RNA polymerase II (RNA nucleotidyltransferase II) stimulation factor isolated from the nuclei of chicken myeloblastosis cells was studied. The stimulation requires the presence of all four nucleoside triphosphates and depends upon an exogenous DNA template. In the absence of the factor, RNA synthesis ceases after 20-30 min, but in the presence of the factor, synthesis continues up to 60-80 min. Addition of the factor at 35 min after incubation causes resumption of RNA synthesis. The factor greatly stimulates the activity of RNA polymerase II at low enzyme concentrations. The RNA polymerase activity is more sensitive to alpha-amanitin inhibition when the factor is present. Experiments of [gamma-32P]ATP incorporation reveal that the factor provides for an increased frequency of initiation of RNA chains, both of the primary initiation events and re-initiation after previous ones were completed. A slightly higher rate of RNA chain growth was also observed with this factor but the ultimate size of RNA synthesized was not affected, as determined by formaldehyde/sucrose gradient centrifugation. These data suggest that the factor functions at the initiation stages of the RNA polymerase reaction.
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PMID:Increased frequency of initiation of RNA synthesis due to a protein factor from chicken myeloblastosis nuclei. 105 84

The marrow of chicks with leukemia induced by avian 'myeloblastosis' virus (AMV) exhibited a 5-10-fold increase in the number of fibroblast colony-forming cells (CFU-F). The increased CFU-F correlated with a mild fibrosis which can be seen in the marrow of these animals. Fibroblast proliferation likely was not simply due to the presence of leukemic cells because addition of formaldehyde-fixed peripheral leukemic cells failed to initiate CFU-F growth. Conditioned medium (CM) from day-4 cultures of peripheral leukemic cells was markedly stimulatory to CFU-F growth. The stimulatory activity was not due to virus released from the leukemic cells as, (1) removal of virus by pelleting had no effect on the CM activity and (2) direct inoculation of CFU-F cultures with virus failed to stimulate CFU-F growth. Normal avian marrow macrophage monolayers also released high levels of a fibroblast growth factor and both the macrophage-derived and leukemic cell-derived factors were heat-labile (65 degrees, 30 min).
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PMID:Avian monocytic leukemia cells release fibroblast growth factor: implications to associated myelofibrosis. 386 25

Confluent, quiescent chick embryo fibroblasts maintained in protein-free medium released CSF(s) active on granulocyte and monocyte progenitors and on monocytic leukemia cells induced by avian 'myeloblastosis' virus (AMV) when exposed to formaldehyde-fixed AMV leukemic cells. The CSF was assayed under serum-free conditions. Of several normal cell types tested including populations enriched for blast cells, only macrophages exhibited this capacity.
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PMID:Induction of colony-stimulating factor from quiescent fibroblasts by avian macrophages and monocytic leukemic cells. 393 82

Thymus glands of chicks with leukemia induced by BAI strain A (myeloblastosis) virus were fixed in cold 4 per cent formaldehyde-sucrose. Frozen sections were incubated in the ATPase medium of Wachstein and Meisel and studied by light microscopy and electron microscopy. The ATPase activity of the virus is localized to the outermost membrane of the virus. The membrane of the blast-like cells of the thymus cortex from which the virus emerges, by budding, also possesses such activity. It appears likely that the outermost membrane of the virus is derived from the plasma membrane of these cells.
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PMID:Electron microscopic study of the ATPase activity of the BAI strain A (myeloblastosis) avian tumor virus. 1393 25