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)

Using cultured bovine aortic endothelial cells, the effects of MCI-186, a radical scavenger, were studied on arachidonic acid metabolism and on the cell injury caused by 15-HPETE. MCI-186 at 3 X 10(-5) M enhanced prostacyclin production in the intact endothelial cells without affecting phospholipase A2. When endothelial cell homogenates were used as an enzyme source, it was found that MCI-186 stimulated the conversion of arachidonic acid to prostacyclin like phenol, perhaps by trapping OH radicals produced in the process of the conversion of PGG2 to PGH2. On the other hand, MCI-186 was found to inhibit lipoxygenase metabolism of arachidonic acid in cell free homogenates of rat basophilic leukemia cells. The lipoxygenase inhibition caused by 3 X 10(-5) M MCI-186 was almost equivalent to that caused by 3 X 10(-6) M BW 755C. MCI-186 remarkably protected against endothelial cell damage caused by 15-HPETE. 3 X 10(-5) M of 15-HPETE caused endothelial cell death in about 60% of the population: however, pretreatment of the cells with 10(-5) M of MCI-186 or concomitant addition of 10(-5) M of MCI-186 with 15-HPETE to the cultures prevented the cell death completely. These results suggest that MCI-186 may become an unique anti-ischemic drug.
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PMID:Preventive effect of MCI-186 on 15-HPETE induced vascular endothelial cell injury in vitro. 314 37

In the absence of any specific literature on the isolation of RNA from mast cells, our initial attempts established that unusual measures would be needed to prepare acceptable yields of high quality RNA from peritoneal mast cells of normal adult rats. Accordingly, we developed procedures for the isolation and characterization of RNA from rat peritoneal mast cells (PMC) and basophilic leukemia cells (RBL). The significant components of the procedures include: separation and removal of mast cell granules to minimize contamination of RNA with proteins and proteoglycans; use of bentonite in phenol extractions; and repetition of extractions and precipitation. The amounts of total RNA extracted from PMC were about 15% of those from RBL, although the percentage mRNA of total RNA in PMC and RBL was similar (1.8 and 2.0%). Ribosomal RNA banding patterns in agarose gel electrophoresis and in vitro translation experiments indicate that the isolated RNA can be employed for analysis of molecular mechanisms of mast cell function and heterogeneity.
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PMID:Isolation and in vitro translation of mRNA from rat peritoneal mast cells and rat basophilic leukemia cells. 318 93

Benzene is a heavily used industrial chemical, a petroleum byproduct, an additive in unleaded gas, and a ubiquitous environmental pollutant. Benzene is also a genotoxin, hematotoxin, and carcinogen. Chronic exposure causes aplastic anemia in humans and animals and is associated with increased incidence of leukemia in humans and lymphomas and certain solid tumors in rodents. Bioactivation of benzene is required for toxicity. In the liver, the major site of benzene metabolism, benzene is converted by a cytochrome P-450-mediated pathway to phenol, the major metabolite, and the secondary metabolites, hydroquinone and catechol. The target organ of benzene toxicity, the hematopoietically active bone marrow, metabolizes benzene to a very limited extent. Phenol is metabolized in the marrow cells by a peroxidase-mediated pathway to hydroquinone and catechol, and ultimately to quinones, the putative toxic metabolites. Benzene and its metabolites appear to be nonmutagenic, but they cause myeloclastogenic effects such as micronuclei, chromosome aberrations, and sister chromatid exchange. It is unknown whether these genomic changes, or the ability of the quinone metabolites to form adducts with DNA, are involved in benzene carcinogenicity. Benzene, through its active metabolites, appears to exert its hematological effects on the bone marrow stromal microenvironment by preventing stromal cells from supporting hemopoiesis of the various progenitor cells. Recent advances in our understanding of the mechanisms by which benzene exerts its genotoxic, hematotoxic, and carcinogenic effects are detailed in this review.
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PMID:Recent advances in the metabolism and toxicity of benzene. 331 42

gamma-L-glutaminyl-4-hydroxybenzene, a stable phenol found in high concentrations in the gill tissue of the common mushroom, Agaricus bisporus, was shown to be capable of selectively inhibiting DNA synthesis in L1210 leukemia cells. Studies with isolated enzymes and permeabilized L1210 cells revealed that this compound inhibits ribonucleotide reductase ( RNR ) but has no effect on DNA polymerase. The results indicated a good correlation between the inhibition of DNA synthesis and the ability of this compound to inhibit RNR . The concentration of glutaminyl-4-hydroxybenzene required to elicit these inhibitory effects has physiological relevance to the gill tissue during the prodromal period of sporulation.
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PMID:Inhibition of ribonucleotide reductase by naturally occurring quinols from spores of Agaricus bisporus. 637 59

Benzene has the sad privilege of being the only industrial chemical inducing leukemia in susceptible individuals chronically exposed to its vapors. Hence, benzene has been included in the list of human carcinogens. Acute myeloblastic leukemia and erythroleukemia are typical examples of benzene leukemia. Most cases show some features in common: 1) development after many years of exposure and, in some cases many months after leaving the toxic atmosphere; 2) leucopenia or moderate degree of leucocytosis; and 3) splenohepatomegaly discrete or absent. Finding of an antecedent of pancytopenia reinforces the suspicion of benzene as the causative agent. There is still no agreement about the role played by benzene in chronic types of leukemia. In assessing diagnosis of benzene leukemia much importance has been attached by French authors and by myself to the demonstration of benzene in blood or in bone marrow aspirates or biopsies. Treatment of benzene hemopathy based on the oral administration of "anti-benzene compounds" such as methyl-donors and thiol-aminoacids is proposed here based on personal research in rabbits, in leukemic patients treated by benzene in the past and on myself as a volunteer. In pre-leukemic states, lowering the benzene burden of the bone marrow might prevent the further development of acute leukemia. Recently, I found out that: 1) benzene can be converted to phenol in the bone marrow independently of liver oxidizing enzymes; 2) benzene injected in the femoral artery of the rabbit can provoke histological changes at the isolated tibial marrow.
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PMID:An hypothesis for the induction of leukemia by benzene. 657 48

A series of even numbered fatty acid esters (C2-C18) of p-[N,N-bis(2-chloroethyl)amino]phenol were synthesized and evaluated as to acute toxicity as well as effectiveness against L-1210 mouse leukemia. The acetate through the decanoate derivatives demonstrated toxicity between 2 and 3 times that of phenol mustard in HA/ICR mice. The less soluble laurate, myristate, palmitate, and stearate derivatives were less toxic. Significant survival times in the leukemia studies (T/C% greater than or equal to 125) were observed for all compounds except the acetate and hexanoate derivatives. The myristate derivative produced the greatest significant increase in survival time, 162%. The palmitate and stearate derivatives produced significant survival at five and four dosage levels, respectively. The butyrate and laurate derivatives produced significant survival at three dosage levels and the octanoate, decanoate, and myristate at two dosage levels.
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PMID:Synthesis and bioevaluation of a series of fatty acid esters of p-[N,N-bis(2-chloroethyl)amino]phenol. 712 60

Messenger ribonucleic acid (mRNA) for thymus-leukemia antigens, membrane-associated glycoproteins of murine leukemia cells, was obtained from polysomes of murine leukemia cells forming thymus-leukemia antigens. Polysomes forming thymus-leukemia antigens were recovered by immunoprecipitation using alloantibodies specific for the 1,2,3 determinants of the thymus-leukemia antigen complex before they were extracted with phenol-detergent. Poly(adenylic acid)-containing RNA [poly(A)-RNA] was fractionated by oligo[deoxythymidylate] [oligo(dT)]-cellulose chromatography. The mRNA obtained had a sedimentation coefficient of approximately 17 S in agreement with the predicted size necessary for forming proteins specifying thymus-leukemia antigens. In a wheat germ system, the polypeptides formed upon addition of mRNA for thymus-leukemia antigens consisted of a major product with a molecular weight of 42,000. It was larger than the nonglycosylated heavy chain molecule of 40,000 daltons formed by the cells themselves. On the cell surface thymus-leukemia antigens exist as glycosylated molecules of 47,000 daltons associated with a light-chain equivalent to beta 2-microglobulin. Molecules of 40,000 daltons were isolated from the cells cultured in the presence of tunicamycin, an inhibitor of de novo glycosylation, and by treating thymus-leukemia heavy chains with endo-beta-N-acetylglucosaminidase H.
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PMID:Isolation and cell-free translation of messenger ribonucleic acids specifying thymus-leukemia antigens. 745 38

Benzene, an important industrial solvent and constituent of unleaded gasoline, causes leukemia and aplastic anemia in humans. Mice are more sensitive than rats to benzene toxicity, though neither species has been shown to respond consistently with benzene-induced leukemia. Benzene biotransformation in liver to phenol, hydroquinone, catechol and/or muconaldehyde is thought to be necessary for its hematotoxicity and/or genotoxicity. Our goal is to develop a mathematical simulation model capable of describing the pathways and kinetics of benzene metabolism by rat and mouse liver microsomes and to assess the role of species metabolic differences in species sensitivity. Microsomes were incubated with 4 microM [U-14C]-benzene or 4 microM [U-14C]phenol. Metabolite production was quantified by extraction into ethyl acetate, HPLC separation and liquid scintillation spectroscopy. After 45 min, mouse liver microsomes converted 20% of the benzene to phenol, 31% to hydroquinone and 2% to catechol. Rat liver microsomes converted 23% of benzene to phenol, 8% to hydroquinone and 0.5% to catechol. Production of hydroquinone and catechol continued for 90 min for mouse liver microsomes, while production by rat liver microsomes had virtually ceased by 90 min. Muconic acid production by mouse liver microsomes was < 0.2% and < 0.04% from benzene and phenol respectively after 90 min. A quantitative simulation model was constructed to describe the in vitro metabolism of benzene, incorporating the reaction sequences: benzene-->phenol-->catechol-->trihydroxybenzene and phenol-->hydroquinone-->trihydroxybenzene. In the model, all of the reaction steps are assumed to be catalyzed by the same enzyme(s), cytochrome(s) P450, and benzene, phenol, hydroquinone and catechol in solution are all assumed to compete, through reversible binding, for the same reaction site(s) on cytochrome(s) P450. The simulation model accurately described both the benzene and phenol kinetic data, supporting this proposed mechanism. In particular, this model suggests that the observed inhibition of benzene on phenol metabolism, and of phenol on benzene metabolism, occurs through competition for a common reaction site, which can also bind catechol and hydroquinone.
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PMID:Benzene and phenol metabolism by mouse and rat liver microsomes. 826 15

The myelotoxicity, including leukemia, associated with benzene exposure has been attributed to the further activation of benzene-derived metabolites. In a previous study, we observed that (Cu(II) strongly mediates the oxidation of hydroquinone (HQ) producing benzoquinone (BQ) and H2O2 through Cu(II)/Cu(I) redox mechanism. Since copper exists in the nucleus and is closely associated with chromosomes and DNA, in this study we investigated whether this chemical--metal redox system induces strand breaks in phi X-174 RFI plasmid DNA. In the presence of micromolar concentrations of Cu(II) and HQ, both single and double strand breaks were induced, whereas HQ, Cu(II), H2O2 or BQ alone at the employed concentrations elicited no significant damage to DNA. The HQ/Cu(II) system was at least twice as efficient as a H2O2/Cu(II) system at inducing DNA strand breaks. Of Cu(II), Fe(III), Mn(II), Cd(II) and Zn(II), only HQ/Cu(II) induced extensive DNA strand breaks. Among HQ, 1,2,4-benzenetriol (BT), catechol and phenol, HQ/Cu(II) and BT/Cu(II) were the two most efficient DNA cleaving systems. The presence of bathocuproinedisulfonic acid (BCS) or catalase prevented the HQ/Cu(II)-induced DNA strand breaks. In addition, the HQ/Cu(II)-induced DNA strand breaks could be completely blocked by reduced glutathione and dithiothreitol, but not by L-cysteine. The interaction of L-cysteine with copper in the absence of HQ induced significant DNA strand breaks with the same pattern of DNA strand breaks as that of HQ/Cu(II) plus L-cysteine. In contrast to the HQ/Cu(II) system, a HQ/myeloperoxidase (MPO)/H2O2 system did not induce any DNA strand breaks, and furthermore, the presence of MPO inhibited the HQ/Cu(II)-induced DNA strand breaks. When DNA pretreated with Cu(II) was exposed to HQ, DNA strand breaks were formed that could be prevented by BCS or catalase, indicating that DNA-bound copper can undergo redox cycling in the presence of HQ, generating H2O2. Similar to the H2O2/Cu(II) system, the HQ/Cu(II)-induced DNA strand breaks could not be efficiently inhibited by hydroxyl radical scavengers but could be protected by singlet oxygen scavengers, indicating that the localized generation of singlet oxygen or a singlet oxygen-like entity, possibly a copper-peroxide complex, rather than free hydroxyl radical probably plays a role in the HQ/Cu(II)-induced DNA strand breaks. The above results suggest that macromolecule-associated copper and reactive oxygen generation may be important factors in the mechanism of HQ-induced DNA damage in target cells.
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PMID:DNA damage resulting from the oxidation of hydroquinone by copper: role for a Cu(II)/Cu(I) redox cycle and reactive oxygen generation. 839 44

Adduction of hemoglobin (Hb) and bone-marrow proteins with 1,2- and 1,4-benzoquinone (1,2-BQ and 1,4-BQ) and 4,4'-diphenoquinone was examined following oral administration of [13C6]benzene to F344 rats. Linear production of [13C6]1,4-BQ adducts was observed with both Hb and bone-marrow proteins over the entire range of dosages of 0-400 mg/kg. The slopes of the regressions were 3.4 x 10(-4) (r2 = 0.997) and 1.6 x 10(-3) (r3 = 0.926) nmol/g protein/mg/kg respectively, for Hb and bone-marrow proteins. Production of [13C6]1,2-BQ adducts of Hb and bone-marrow proteins also increased with benzene dosage. Although the shapes of the relationships between 1,2-BQ adducts and dosage were nonlinear, the levels were approximately 10 times greater than those associated with 1,4-BQ, suggesting a significantly greater benzene-specific dose of 1,2-BQ. Adducts of 4,4'-diphenoquinone were not detected. High background levels of [12C6]adducts of 1,2-BQ and 1,4-BQ were found in Hb and bone-marrow proteins as might be expected from the many dietary sources of the phenolic precursors of the benzoquinones, i.e. phenol, catechol and hydroquinone. Background levels of the 1,2-BQ and 1,4-BQ adducts were 27.3 and 11.5 nmol/g in Hb and 44.6 and 25.6 nmol/g in the bone-marrow proteins respectively. Interestingly, the production of benzene-specific adducts represented only a small fraction (< 4%) of the background levels of the same adducts. If the genotoxicity of benzene is, indeed, related to the in vivo production of BQ isomers, our results suggest that very large exposures to benzene would be needed to produce detectable increases in adduct levels and the associated risks of leukemia.
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PMID:Production of benzoquinone adducts with hemoglobin and bone-marrow proteins following administration of [13C6]benzene to rats. 840 19


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