Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

cCMP-specific phosphodiesterase activity was demonstrated in the 80 to 100% ammonium sulfate fraction obtained from disrupted leukemia L-1210 cells. The activity was linear with time (up to 60 min), was a function of protein concentration, and was markedly stimulated by Mg2+ and by ammonium sulfate. Under identical assay conditions, no significant hydrolysis of cAMP or cGMP was observed, although these cyclic nucleotides served as substrates for phosphodiesterase(s) present in all the fractions obtained by less than 80% ammonium sulfate saturation. This is the first demonstration of a cCMP-specific phosphodiesterase.
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PMID:Demonstration, in leukemia L-1210 cells, of a phosphodiesterase acting on 3':5'-cyclic CMP but not on 3':5'-cyclic AMP or 3':5'-cyclic GMP. 20 54

Multiple forms of RNA polymerases (I, II and III) from murine leukemia L1210 cells are solubilized, purified and characterized. Heterogeneity of RNA polymerases I and III is revealed by chromatography on DEAE-Sephadex and Phosphocellulose (P-11). The properties of these forms such as peculiarities of transcription of native and denaturated DNA, metal ion dependence (Mg2+, Mn2+ and (NH4)2SO4) and alpha-amanitin sensitivity resemble those reported for other mammalian RNA polymerases. The level of RNA polymerase I of leukemia L1210 cells increase approximately ten-fold relative to its level in some organs of healthy mice.
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PMID:[RNA-polymerase of murine leukemia L1210 cells]. 62 42

The RNA polymerase activities from the nuclei of the spleen of uninfected and Rauscher murine leukemia virus-infected NIH Swiss mice were resolved by DEAE-cellulose column chromatography, and their properties were compared. The RNA polymerase activities from infected and uninfected spleens were the same with respect to column elution profiles, optimum requirements for various salts, ratios of activities with Mn2+ and Mg2+, sedimentation values, and response to most templates. With the exception of minor differences in activities with certain DNA templates, the significance of which is not clear, no qualitative differences in the enzymes from these two sources were found, but an increase in the specific activity of the alpha-amanitin sensitive enzyme, RNA polymerase II, was found in the leukemic spleen. These preliminary results suggest that there may be no novel RNA polymerase induced by Rauscher murine luekemia virus-infection, and they are in keeping with the interpretation that the viral DNA genome is transcribed by a host RNA polymerase.
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PMID:Deoxyribonucleic acid-dependent ribonucleic acid polymerases from spleen of uninfected and Rauscher murine leukemia virus-infected NIH Swiss mice.? 112 31

The high-molecular-weight RNA of Moloney murine leukemia virus (MuLV) was analyzed by sedimentation equilibrium ultracentrifugation. Molecular weights of 7.2 x 10(6) and 3.4 x 10(6) were found for the native and subunit forms, respectively, indicating that the native structure is a dimer. S20,w and frictional coefficients were determined for MuLV RNA by analytical velocity centrifugation as a function of ionic strength. The apparent S20,w of native MuLV RNA was 47.3, 57.4, and 66.5 in 0.01, 0.1, and 0.20 M Na+, respectively; the corresponding frictional coefficients were 5.44, 4.48, and 3.87. Native RNA was estimated by circular dichroism to be 85% helical, whereas denatured RNA was 54% helical. Thermal denaturation profiles were obtained from uv absorbance scans. Melting temperatures of 57 and 68 C were obtained for high-molecular-weight RNA in 0.01 M Na+ and 0.122 M Na+, 1mM Mg2+, respectively. van't Hoff plots of the thermal denaturation data gave enthalpies for the helix-coil transition of 21,600 cal (ca. 90,500 J) per mol of cooperatively melting unit in high salt and 19,600 cal (ca. 82,100 J) per mol in low salt, consistent with both base stacking and pairing. The melting of Mu LV RNA occurred over a broad temprange and van't Hoff plots were linear over most of the melting range, indicating a noncooperative process of helix stabilization.
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PMID:Physical properties of moloney murine leukemia virus high-molecular-weight RNA: a two subunit structure. 120 47

Detection of viral RNA by polymerase chain reaction (PCR) requires the prior reverse transcription of the viral RNA. In order to minimise the number of manual manipulations required for processing large numbers of samples, we attempted to design a system whereby all the reagents required for both reverse transcription and amplification can be added to one tube and a single, non-interrupted thermal cycling program performed. Whilst attempting to set up such a one-tube system with Taq polymerase (Taq; Biotech International) and avian myoblastosis virus (AMV) reverse transcriptase (RT), we noticed a substantial decrease in the sensitivity of detection of viral RNA. Investigation of this phenomenon has revealed direct interference of RT with Taq polymerase. Evidence supporting this conclusion includes the following observations: (1) increasing the ratio of Taq to RT improves sensitivity; (2) adding non-homologous RNA improves sensitivity; (3) RT that has been heat inactivated prior to Taq addition does not exert this effect; (4) the effect is not sequence restricted; (5) the Mg2+ ions are not sequestered by RT. In addition, the effect is not limited to AMV RT, Moloney murine leukaemia virus RT also affects Taq activity.
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PMID:Reverse transcriptase inhibits Taq polymerase activity. 137 54

Cobra venoms cause irreversible destruction of cells cultured in vitro [1,2]. The venom of Naja nigricollis nigricollis possessed the most potent cytotoxic activity towards B16F10 melanoma cells among various examined venoms [2]. The main cytotoxic factor (P4) isolated from this venom showed preferential activity on tumor cell lines and caused lysis at concentrations of 10(-7) M (0.8-1 micrograms/ml) [3]. The present study examined the binding of cytotoxin P4 to melanoma B16F10 and WEHI-3B leukemia cell lines and found that, like cytotoxicity, it depended on concentration, temperature and incubation time. Cytotoxin concentrations that elicited no apparent damage to cells during the first hour of incubation caused lysis after a longer period of incubation, suggesting that a critical number of bound molecules is required in order to cause cell death. Bivalent ions, such as Mg2+, Ca2+ or Sr2+, which decreased binding to the cells also inhibited cytotoxicity. Competition experiments as well as the displacement of 75% of the bound radiolabelled cytotoxin with 'cold' cytotoxin, suggest the presence of specific binding sites for the toxin in the examined tumor cells. The non-specific binding of the cytotoxin P4 to sea urchin ova and sperm cells without affecting their fertility, even at high concentrations of 10(-5) M, indicates that the specific binding to cells is probably a necessary condition for cell lysis.
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PMID:Binding of cytotoxin P4 from Naja nigricollis nigricollis to B16F10 melanoma and WEHI-3B leukemia cells. 141 10

The genome of human immunodeficiency virus (HIV) and especially the envelope gene are mutated with unusually high frequency during in vivo replication. Recent studies indicate that HIV reverse transcriptase (RT) is unusually error prone and that the number of generated mutations is disproportionately high within repetitive base sequences. To study the ability of recombinant and wild-type HIV RT to traverse specific homo-oligomeric stretches, we used bacteriophage M13 DNA templates that contain different oligo(purine) and oligo(pyrimidine) inserted tracts. The progress of HIV RT along these templates was potently inhibited from further progression only at a (dA)16 insert. Comparison with other polymerases indicates that the almost complete blockage of polymerization beyond an oligo(dA) insert is unique to HIV RT and Moloney murine leukemia virus RT, which has high sequence homology with HIV RT. The extent of termination of HIV RT at the oligo(dA) run is not affected by alterations in the concentration of KCl, Mg2+, dNTP, or by a decrease in pH. Obstruction of HIV RT opposite the oligo(dA) insert is not alleviated by moving the primer position further upstream from the oligo(dA) insert. Lastly, HIV RT purified directly from virions is also specifically arrested at an oligo(dA) tract. Competition experiments indicate that the concentration of active HIV RT in the presence of M13(dA)16 DNA is similar to that observed in the presence of M13(dG)16 DNA. In addition, preincubation of M13(dA)16 DNA with HIV RT does not subsequently inhibit avian myeloblastosis virus RT from successfully traversing the (dA)16 insert. Therefore, it appears that the blockage of chain elongation of HIV RT at the (dA)16 insert is not the result of trapping the enzyme at this site.
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PMID:Synthesis of DNA by human immunodeficiency virus reverse transcriptase is preferentially blocked at template oligo(deoxyadenosine) tracts. 169 89

A fragment of the SIVmac251 pol gene was expressed in Escherichia coli as a trpE fusion protein. Analysis of extracts from bacteria containing this expression plasmid revealed the presence of a reverse transcriptase activity dependent on Mg2+ as divalent cation and active on both poly(rA).oligo(dT) and poly(rC.oligo(dG) templates. In comparative studies, the SIV and HIV-1 reverse transcriptases expressed in bacteria displayed very similar high sensitivities to the chain terminator inhibitors AZTTP and ddTTP. The reverse transcriptase of Moloney murine leukemia virus and the DNA polymerase of E. coli were both more resistant to ddTTP, and the E. coli enzyme was significantly more resistant to AZTTP.
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PMID:Expression of enzymatically active reverse transcriptase of simian immunodeficiency virus in bacteria: sensitivity to nucleotide analogue inhibitors. 170 May 44

Reverse transcriptase (RT) transcribes viral RNA into DNA to be integrated into the host genome. To study epidemiological aspects of human leukemias and lymphomas which are known to express retroviruses, clinical specimens in this report were assayed for divalent cation-dependent viral-specific RT. The assay was carried out with cells solubilized with a detergent to release RT enzyme. RT was purified with poly(U)-Sepharose which fixed all DNA polymerases and assayed with 4 synthetic homopolymers, oligonucleotide primed-templates, poly(rA)-oligo(dT)12-18 or poly(dA)-oligo(dT)12-18 with Mg2+, poly(rC)-oligo(dG)12-18 or poly(rCm)-oligo(dG)12-18 with Mn2+ as divalent cation and [methyl-3H]thymidine 5'-triphosphate or deoxy[8-3H]guanosine 5-triphosphate respectively. Radioactivity incorporation of the precipitate allows quantitation of RT activity. One Hodgkin's disease, one out of 2 B lymphomas, one out of 2 T lymphomas, eight out of 12 leukemias were found to be positive for RT activity as well as acquired immunodeficiency syndrome (AIDS) patients, known to express RT. The obtained RT activity in hematological malignancies was found to be comparable to positive controls such as RT enzymes purified from avian myeloblastosis and Moloney murine leukemia viruses.
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PMID:Presence of reverse transcriptase in human leukemias and lymphomas. 170 70

Receptors for the chemotactic peptide fMet-Leu-Phe (fMet, N-formylmethionine) are present in membranes of myeloid differentiated human leukemia (HL-60) cells and stimulate phospholipase C via a pertussis-toxin-sensitive guanine-nucleotide-binding regulatory protein(s) [G-protein(s)]. We have developed methods for the assessment of formyl-peptide-receptor-stimulated binding of radiolabeled guanosine 5'-[gamma-thio]triphosphate ([35S]GTP[S]) to native HL-60 membranes. Agonist stimulation of [35S]GTP[S] association with the membrane was minimal (less than or equal to 20%) when GTP[S] was the sole nucleotide present in the incubation medium. In contrast, receptor activation led to a marked (up to sixfold) stimulation of [35S]GTP[S] binding when GDP or GTP were present in high (greater than 100-fold) excess of [35S]GTP[S]. The increase in [35S]GTP[S] binding caused by the chemotactic agonist was strictly dependent on the presence of Mg2+ and was significantly increased by Na+. Agonist-independent binding of [35S]GTP[S] and the increase due to the chemotactic agonist were markedly attenuated by both pertussis and cholera toxin. Comparison of the number of chemotactic-peptide-sensitive [35S]GTP[S]-binding sites to the number of chemotactic peptide receptors present in HL-60 membranes provided direct evidence that a single formyl-peptide receptor is capable of catalyzing the binding of [35S]GTP[S] to, and thus the activation of, multiple (up to 20) G-proteins in native plasma membranes.
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PMID:Signal amplification in HL-60 granulocytes. Evidence that the chemotactic peptide receptor catalytically activates guanine-nucleotide-binding regulatory proteins in native plasma membranes. 190 7


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