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

Using [32P]histone as substrate, an assay for histone phosphate phosphatase was optimised for human polymorphonuclear leukocytes. Kinetic studies showed that the activity was optimal at pH 6.8, was stimulated by Mn2+ and Co2+, and inhibited by sodium sulphite and zinc chloride. The apparent Km of the enzyme for histone phosphate was 0.89 mumol/l. Neutrophils were homogenized in isotonic sucrose and, after low speed centrifugation, the supernatant was subjected to analytical subcellular fractionation. Gradient fractions were assayed for principal marker enzymes and for histone phosphate phosphatase. Histone phosphate phosphatase activity was shown to be solely located to the cytosol. No activity was detected in the alkaline phosphatase-containing granules. Neutrophils were isolated from the blood of control subjects, patients with chronic granulocytic leukaemia and women in the third trimester of pregnancy. The specific activity (milliunits/mg protein) of histone phosphate phosphatase was significantly reduced in patients with chronic granulocytic leukaemia compared to control values but this decrease was considerably less than that found for alkaline phosphatase. The possible implication of the reduced histone phosphatase activity in leukaemia neutrophils is discussed. There was no significant change in histone phosphate phosphatase in leucocytes from pregnant women. These results, together with the subcellular fractionation experiments and inhibitor studies, strongly indicate that histone phosphate phosphatase is not attributable to neutrophil alkaline phosphatase.
 ...
PMID:Subcellular localisation and properties of histone phosphate phosphatase in human polymorphonuclear leukocytes: alterations in pregnancy and chronic granulocytic leukaemia and relationship to alkaline phosphatase. 693 12

The levels of copper, zinc, calcium, manganese and magnesium have been monitored in the sera of patients suffering from various types of cancer. Only serum copper appeared to be of any diagnostic significance, its levels being above the normal reported range in the breast cancer, leukaemia and Hodgkin's lymphoma patients. In the case of breast cancer, serum copper is progressively elevated according to the stage of the disease. Serum calcium levels were also significantly lower in patients with tumours of the breast, gastrointestinal tract and cervix. The results suggest that serum copper levels could be of prognostic significance in breast cancer patients receiving radiotherapy.
 ...
PMID:The serum levels of some trace and bulk elements in cancer patients. 705 45

We have shown that pyridoxal 5'-phosphate is an effective inhibitor of Rauscher leukemia virus DNA polymerase (Biochemistry 15 (1976) 3620). Detailed studies of this inhibition revealed that, in addition to the phosphate and aldehyde groups of pyridoxal phosphate, the presence of a divalent cation is essential for the inhibitory action. The synthesis directed by template primers containing GC base-pairs exhibited more resistance to pyridoxal phosphate inhibition than did that directed by AT base-paired templates. Maximal inhibitory activity of pyridoxal phosphate, however, is noted in the presence of Mn2+, irrespective of which template-primer is used to direct the DNA synthesis. The action of pyridoxal phosphate on the substrate binding site may be deduced from the observations that: (a) only the substrate triphosphate is able to reverse the pyridoxal phosphate-mediated inhibition; (b) the inhibition kinetics exhibit a classical competitive pattern with the substrate; (c) analogous to substrate deoxynucleoside triphosphates the inhibitor is also accepted only in the form of its divalent metal ion complex; and (d) substrate site-specific labeling of RLV DNA polymerase has been shown to occur by linking covalently the pyridoxal phosphate bound to a lysine residue at the substrate binding site.
 ...
PMID:Divalent cation-dependent pyridoxal 5'-phosphate inhibition of Rauscher leukemia virus DNA polymerase: characterization and mechanism of action. 728 79

In the presence of Mn2+, reverse transcriptase of both human immunodeficiency virus and murine leukemia virus hydrolyzes duplex RNA. However, designating this novel activity RNase D conflicts with Escherichia coli RNase D, which participates in tRNA processing. On the basis of its location in the RNase H domain, we propose that this novel retroviral activity be redesignated RNase H*.
 ...
PMID:Redesignation of the RNase D activity associated with retroviral reverse transcriptase as RNase H. 750 4

The effect of the H1-antihistamine drug loratadine and its active metabolite descarboxyethoxyloratadine upon histamine release was examined on anti-immunoglobulin E (IgE) triggered human basophils and 2,4-dinitrophenyl (DNP) triggered rat basophilic leukemia (RBL-2H3) cells. In both experimental systems, dose-dependent inhibition of histamine release was observed at descarboxyethoxyloratadine and loratadine doses above 2 and 7 microM, respectively. In the RBL-2H3 experimental system, inhibition by loratadine increased when the concentration of extracellular Ca2+ was reduced from 1.8 to 0.45 mM. We further investigated the effect of loratadine and descarboxyethoxyloratadine on the increase in cytosolic calcium concentration (Ca2+)i, an early step in biochemical events leading to exocytosis. The effect of these two drugs upon (Ca2+)i changes was measured using the fluorescent probe fura-2 loaded into RBL-2H3 cells passively sensitized with DNP-specific IgE. Both drugs inhibited, in a dose-dependent manner (2.5-25 microM), the (Ca2+)i rise induced by DNP-BSA challenge in sensitized RBL cells, a process observed in both the presence and absence of extracellular Ca2+. Loratadine also inhibited the Mn2+ influx into these cells, thus reflecting the Ca2+ influx. These results suggest that loratadine and descarboxyethoxyloratadine impair the increase in (Ca2+)i following cell activation by decreasing both the influx of extracellular Ca2+ and the release of Ca2+ from intracellular stores.
 ...
PMID:In vitro inhibition, by loratadine and descarboxyethoxyloratadine, of histamine release from human basophils, and of histamine release and intracellular calcium fluxes in rat basophilic leukemia cells (RBL-2H3). 751 Sep 65

A putative retrovirus was isolated from a dog with a severe, acquired immunodeficiency-like syndrome. The haematological abnormalities and immunological deficiencies included anaemia, leucopenia (lymphopenia and neutropenia), thrombocytopenia, decreased humoral immunity, and ineffective T-cell responses in-vitro. The necropsy findings included generalized lymphoid depletion, severe bone marrow hypoplasia, plasmacytic infiltrates in lymphoid and non-lymphoid organs, and severe secondary infections. Supernates of peripheral blood mononuclear cell cultures from the affected dog contained an agent with manganese-dependent reverse transcriptase (RT) activity that sedimented at a density of 1.122 g/ml. RT activity was also found post-mortem in extracts prepared from the bone marrow, lymph nodes, and small intestine. The lymph nodes and small intestine expressed a 3.8 kb mRNA that was recognized by a bovine leukaemia virus (BLV) pol DNA probe by Northern blotting. DNA isolated from the lymph nodes and small intestine from the affected dog showed distinct band patterns by Southern analysis, suggesting an exogenous retrovirus. The retrovirus could be propagated in normal canine peripheral blood mononuclear cells or short-term canine lymphocyte cell lines in-vitro, and was cytopathogenic for cells of canine, but not human, origin. These results suggest the existence of a pathogenic canine retrovirus capable of producing disease of the type associated with retroviruses in other species.
 ...
PMID:Retrovirus-like activity in an immunosuppressed dog: pathological and immunological findings. 753 63

Antigenic stimulation of rat basophilic leukemia cells releases Ca2+ from internal stores and increases membrane permeability to Ca2+. The delta isomer of hexachlorocyclohexane (delta-HCH) is structurally similar to myo-inositol-1,4,5-trisphosphate (IP3) and is a potent releaser of stored Ca2+ from permeabilized cells. This release of Ca2+ is not mediated by a competitive interaction with the IP3 receptor on the Ca2+ release channel on the endoplasmic reticulum. In intact cells, delta-HCH and, to a lesser extent, lindane (gamma-hexachlorocyclohexane) transiently increase the intracellular Ca2+ concentration. The return to basal concentrations is mediated by the plasma membrane Ca2+ pumps and not by resequestration of Ca2+ into intracellular stores. Treatment of cells with delta-HCH (25-100 microM), but not lindane, leads to a progressive inhibition of the antigen- and thapsigargin-stimulated Ca2+ signal. Caffeine, a modulator of the ryanodine receptor Ca2+ channel, attenuates the rise in intracellular Ca2+ induced by delta-HCH, suggesting that ryanodine receptor-like Ca2+ channels may be present in RBL cells. At 25 microM delta-HCH, a concentration that does not inhibit the antigen-stimulated Ca2+ signal, the release of [3H]serotonin from antigen-stimulated cells is enhanced as is secretion of [3H]serotonin from cells pretreated with 25-100 microM lindane. The depletion of Ca2+ from intracellular stores by delta-HCH should evoke Ca2+ entry into the cells by a capacitative mechanism; however; divalent cation permeability across the plasma membrane (Mn2+ influx) is not increased but rather is decreased by delta-HCH. An understanding of the mechanism of action of delta-HCH in releasing stored Ca2+ and blocking Ca2+ influx across the plasma membrane may provide insights into the regulation of capacitative Ca2+ entry in nonexcitable cells.
 ...
PMID:The delta isomer of hexachlorocyclohexane induces rapid release of the myo-inositol-1,4,5-trisphosphate-sensitive Ca2+ store and blocks capacitative Ca2+ entry in rat basophilic leukemia cells. 756 33

Cyclopiazonic acid has been reported to inhibit the Ca(2+)-ATPase of intracellular calcium stores in some nonexcitable cell types, such as myeloid cells and lymphocytes. The present study examines the effects of cyclopiazonic acid on rat basophilic leukemia (RBL) cells, a mucosal mast cell line. Addition of cyclopiazonic acid to fura-2-loaded RBL cells evoked a biphasic increase in free ionized intracellular calcium. Release of stored calcium accounted for the first phase of this response. The second phase was determined to be calcium entering through an influx pathway activated by cyclopiazonic acid. The influx pathway was selective for calcium, but was somewhat permeable to manganese. However, in a Ca(2+)-free solution containing EGTA, sodium ions permeated freely. This influx pathway appears to be identical to that which is activated by antigen, the physiological stimulus to the cells. Cyclopiazonic acid also induced secretion when combined with the phorbol ester 12-O-tetradecanoyl phorbol 13-acetate, which activates protein kinase C.
 ...
PMID:Ca(2+)-ATPase inhibitor, cyclopiazonic acid, releases Ca2+ from intracellular stores in RBL-2H3 mast cells and activates a Ca2+ influx pathway that is permeable to sodium and manganese. 779 Mar 92

The toxic effects of environmental factors at work places on the hematopoietic and immune systems are of basic importance due to the time of exposure, lasting on average 8 hours daily during one week. Porphyrinurias and porphyrias have been observed after exposure to hexachlorobenzene, chlorinated dibenzodioxins, polychlorinated biphenyls, polybrominated biphenyls, vinyl chloride and lead. Aplastic anemia may occur after exposure to benzene, pesticides, arsenic, cadmium and copper compounds. Megaloblastic anemia has been noted in subjects exposed to arsenic, chlordane, benzene and nitrous oxide. Methemoglobinemia is induced by aromatic nitro and amino compounds. Hemolytic reactions caused by arsenic, methyl chloride, naphthalene, lead, cadmium and mercury compounds represent a separate problem. Immunodeficiencies resulting in decreased antitumor and antiinfectious immunity have been reported in subjects exposed to asbestos, ozone, dimethylsulphoxide, vinilidene chloride, and benzene homologues. Lymphocytopenia may be induced by manganese, lead, toluene and industrial noise. Neutropenia was marked after exposure to carbon disulphide, arsenic compounds, benzene and electromagnetic fields. Only a few reports concern the lymphocyte T3, T4 and T8 subpopulations. Electromagnetic fields (microwaves) cause an imbalance of that subpopulation, consisting of a decrease in the T8 cell count. The neutrophil enzymes, such as myeloperoxidase and alkaline phosphatase, decrease in their activity after exposure to polychlorinated biphenyls, carbon disulphide, chlorobenzene and DDT. A majority of agents cited include genotoxic effects reflected in chromosome aberrations and increased sister chromatid exchange and abnormal unscheduled DNA synthesis. Leukemia or lymphoma risk is increased after exposure to pesticides, electromagnetic fields, benzene and irradiation.
 ...
PMID:Immunotoxic and hematotoxic effects of occupational exposures. 817 62

One major substrate protein was phosphorylated with [gamma-32P]GTP in membranes of human leukemia (HL-60) cells. The phosphoprotein comigrated with beta-subunits of heterotrimeric GTP-binding proteins (G proteins) in different gel systems. Upon solubilization of the phosphorylated membranes, the phosphoprotein could be immunoprecipitated by a G protein beta-subunit-specific antiserum. The beta-subunit phosphorylation was transient and was found to be specific for GTP and its analog, guanosine 5'-O-(gamma-thio)triphosphate. When phosphorylated membranes were incubated with various nucleotides, the bound phosphate was specifically removed by GDP, suggesting that the phosphate can be retransferred onto GDP. Divalent cations, preferentially Mg2+ and Mn2+, were required for both phosphorylation and dephosphorylation. The phosphorylation was stable against treatment with NaOH but sensitive to treatment with heat, HCl, and hydroxylamine. Moreover, treatment of the membranes with the histidine-modifying agent, diethyl pyrocarbonate, resulted in a loss in phosphate incorporation. The data suggest that G protein beta-subunits are involved in a guanine nucleotide-specific enzymatic activity transferring the gamma-phosphate from GTP to GDP, presumably at G protein alpha-subunits, via a phosphohistidine intermediate.
 ...
PMID:Guanine nucleotide-specific phosphate transfer by guanine nucleotide-binding regulatory protein beta-subunits. Characterization of the phosphorylated amino acid. 834 88


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>