Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0002871 (anemia)
 52,094 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A lipoxygenase has been purified from rabbit reticulocyte-rich anaemic blood cells. It possesses a molecular weight of 78 000 and an isoelectric point of 5.5 and contains 5% neutral sugars and two iron atoms per enzyme molecule. The lipoxygenase has proved to be identical with the inhibitors of respiratory proteins described formerly. The actions of the lipoxygenase on linoleic acid, phospholipids, mitochondrial and erythrocyte membranes and electron transfer particles were studied. A special feature of the reticulocyte lipoxygenase is the suicidal character of its action on lipids. With electron transfer particles the reticulocyte lipoxygenase causes a loss of acid-labile sulfur which accompanies respiratory inhibition; the strong respiratory inhibition is not exerted by soybean lipoxygenase. The reticulocyte lipoxygenase acts preferably on mitochondrial membranes as compared with cell membranes of the erythrocyte; erythrocyte cytosol moderates the action on mitochondrial membranes. Furthermore, the lipoxygenase reaction can concomitantly and irreversibly inactivate sulfhydryl enzymes as demonstrated with muscle glyceraldehyde-3-phosphate dehydrogenase. The occurrence of the lipoxygenase here described is restricted to reticulocytes; very low amounts were observed in bone marrow and no lipoxygenase was detectable in normal blood. During the course of an experimental anaemia the lipoxygenase is produced owing to superinduction in large amounts, which may persist for a long time since they escape inactivation. Preliminary evidence was obtained for the occurrence of other lipoxygenases in tissues of lung, spleen, kidney and also epithelial tumours.
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PMID:The lipoxygenase of reticulocytes. Purification, characterization and biological dynamics of the lipoxygenase; its identity with the respiratory inhibitors of the reticulocyte. 11 25

Peripheral rabbit reticulocytes synthesize at least 30 non-globin proteins. One of them is identified as a characteristic lipoxygenase on the basis of its molecular weight, its immunological properties and its behaviour on an ion-exchange column. The enzyme is not produced in bone marrow cells. The synthesis of the lipoxygenase in peripheral blood cells commences on the 3rd day of a bleeding anaemia, increases up to the 5th day and stays constant thereafter at least up to the 14th day. It is concluded that the appearence of the lipoxygenase, which plays a key role in the degradation of mitochondria in the course of maturation of reticulocytes to erythrocytes, is regulated at the translational level.
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PMID:Synthesis of non-globin proteins in rabbit-erythroid cells. Synthesis of a lipoxygenase in reticulocytes. 11 26

Erythrocytes are known to influence hemostasis. Bleeding times are prolonged in anemia and corrected by normalizing the hematocrit. We now demonstrate that intact erythrocytes modulate biochemical and functional responsiveness of activated platelets. A two-stage procedure, permitting studies of cell-cell interactions and independently evaluating platelet activation and recruitment within 1 min of stimulation, was developed. Erythrocytes increased platelet serotonin release despite aspirin treatment, enzymatic adenosine diphosphate removal, protease inhibition, or combinations thereof. The data suggested that erythrocyte enhancement of platelet reactivity can reduce the therapeutic effectiveness of aspirin. Erythrocytes metabolically modified platelet arachidonate or eicosapentaenoate release and eicosanoid formation. They promoted significant increases in cyclooxygenase and lipoxygenase metabolites upon platelet stimulation with collagen or thrombin. However, with ionophore, erythrocytes strongly reduced platelet lipoxygenation. These erythrocyte modulatory effects were stimulus-specific. Activated platelet-erythrocyte mixtures, with or without aspirin, promoted 3-10-fold increases in extracellular free fatty acid, which would be available for transcellular metabolism. Erythrocyte-induced increases in free eicosapentaenoate may contribute to antithrombotic and anti-inflammatory effects of this fish oil derivative. These results provide biochemical insight into erythrocyte contributions to thrombosis and hemostasis, and support the concept of thrombus formation as a multicellular event.
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PMID:Enhancement of platelet reactivity and modulation of eicosanoid production by intact erythrocytes. A new approach to platelet activation and recruitment. 199 40

A lipoxygenase has been found in the reticulocytes of all mammalian species tested so far (rabbit, rat, mouse, monkey, and humans); evidence from in vitro studies suggests that the lipid-peroxidizing effects of this enzyme could render the mitochondrion and other intracellular organelles prone to the proteolytic degradation which is a natural step in development of the reticulocyte to the mature red cell. In this study we sought evidence of an active lipoxygenase in vivo. A bleeding anemia was induced in rabbits, and in the course of the subsequent reticulocytosis the red cell membranes were examined for the presence of the characteristic lipoxygenase products of linoleic and arachidonic acids. Erythrocyte membranes from control collections contained only small amounts of hydroxy fatty acids (0.03-0.08% of the polyenoic fatty acids). In contrast, reticulocyte-enriched red cells contained up to 3.3% of the polyenoic acids as hydroxylated derivatives. The main hydroxy fatty acid in reticulocyte membranes was identified as 13-L(S)-hydroxy-9Z,11E-octadecadienoic acid. Small amounts of other hydroxy derivatives including 15-hydroxy-5,8,11,13-(Z,Z,Z,E)eicosatetraenoic acid were also detected. These products appeared about 3 days after development of reticulocytosis. The precise structures of the hydroxylated polyenoic fatty acids and the time course of their appearance strongly suggest that their formation is due to the intracellular action of the cell-specific reticulocyte lipoxygenase. These findings are the first evidence for an activity of this enzyme in vivo, and the results support the hypothesis that enzymic peroxidation of reticulocyte intracellular membranes is a step in preparation of the intracellular organelles for proteolytic degradation.
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PMID:Occurrence of lipoxygenase products in membranes of rabbit reticulocytes. Evidence for a role of the reticulocyte lipoxygenase in the maturation of red cells. 210 42

It is shown that during recovery from a phenylhydrazine-induced anemia in rabbits a selective decrease in lipoxygenase mRNA takes place with a corresponding shut-off of the synthesis of the enzyme. It is suggested that a new population, 'recovery'-reticulocytes, makes its appearance in the peripheral blood. Their cells are more mature than the stress macroreticulocytes. A cell-free system prepared from the recovery-reticulocytes exhibits low endogenous synthesis of non-globin polypeptides, even without nuclease treatment, but retains full capacity to be stimulated by exogenous mRNA.
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PMID:Evidence for the appearance of a reticulocyte population low in lipoxygenase mRNA during the recovery from a phenylhydrazine-induced anemia in rabbits. 292 15

The lipoxygenase activity of red cell lysates with linoleic acid as substrate, the concentration of immunologically detectable lipoxygenase protein as well as the metabolization of external [1-14C]arachidonic or -linoleic acid by intact cells were determined during bleeding anaemia and the recovery period of rabbits. All three criteria behaved in a parallel manner. Before bleeding no lipoxygenase was detectable. After the third day of strong bleeding high amounts and activities of lipoxygenase appeared in parallel to the appearance of megaloreticulocytes. As few as about a million of cells were sufficient to detect the utilization of [1-14C]polyenoic fatty acids via the lipoxygenase pathway in intact cells in the absence of ionophore A 23187. After discontinuation of strong bleeding the amount and activity of the lipoxygenase declined gradually but persisted for 2-3 months corresponding to the presumed life-span of red cells. Several types of evidence indicate the identity of the lipoxygenase of red cells during the recovery period with that of reticulocytes during strong bleeding: (1) comparable specific activity, (2) Western blot analysis, (3) identical cellular products from [1-14C]-linoleic and -arachidonic acid which were identified by means of HPLC analysis to be 13 S-hydroxyoctadecadienoic acid (13 S-HODE) and 15 S-hydroxyeicosatetraenoic acid (15 S-HETE), respectively. Use of large amounts of cells during the recovery period (5.10(9) cells) led to an apparent masking of the polyenoic fatty acid added. Haemolysis of the cells or addition of calcium and ionophore A 23187 abolished or reduced this masking. Both masking and influence of haemolysis or ionophore disappeared at sufficiently low concentrations of cells. Under these conditions the rate of the formation of lipoxygenase products in intact cells corresponded to the lipoxygenase activity measured in membrane-free cell lysates. In red cells during the recovery period but not during strong bleeding, calcium and ionophore A 23187 stimulated the secondary conversion of 15 S-HETE to more polar products after arachidonic acid had been exhausted. The implications of the results on the performance and the interpretation of the effects of the calcium ionophore A 23187 on cellular arachidonic acid metabolism are discussed.
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PMID:The biological dynamics of lipoxygenase in rabbit red cells in the course of an experimental bleeding anaemia. Unexpected effects of the calcium ionophore A 23187. 314 70

The endogenous oxygen uptake of rabbit reticulocyte-rich red cell suspensions obtained by bleeding anaemia of rabbits amounted to 7.85 +/- 0.87 mumoles/h . ml of packed cells and was inhibited by antimycin A to 77.2 +/- 1.1%. The antimycin A-resistant oxygen uptake was further inhibited by the lipoxygenase inhibitors salicylhydroxamic acid, 5,8,11,14-eicosatetraynoic acid, nordihydroguaiaretic acid, 4-nitrocatechol or propylgallate by about 20-30% corresponding to 5-7% of the total oxygen uptake. The effects of the lipoxygenase inhibitors were most pronounced during the first period of bleeding anaemia (5th-9th day). 3-amino-1,2,4-triazole inhibited another part of the non-respiratory oxygen uptake and acted additively to 5,8,11,14-eicosatetraynoic acid; the two inhibitors together caused inhibition by one-half. Influx of calcium ions mediated by the ionophore A 23187 led to a two-fold increase in the non-respiratory oxygen uptake which was mainly due to stimulation of the lipoxygenase reaction. The rate of the lipoxygenase-mediated oxygen uptake was sufficient for a complete dioxygenation of the polyenoic fatty acids present in mitochondrial phospholipids during the maturational degradation of mitochondria in reticulocytes.
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PMID:The share of lipoxygenase in the antimycin-resistant oxygen uptake of intact rabbit reticulocytes. 392 36

Lipoxygenase activity with linoleic acid as substrate and the immunologically detectable amount of lipoxygenase protein were estimated in the course of in vitro maturation of rabbit reticulocytes withdrawn at the sixth day of an experimental bleeding anaemia. With unseparated cell mixture there was a significant increase in the lipoxygenase activity of 67 +/- 15% after a maturation period of 4 h followed by a decrease up to the initial level. The maturational changes were more pronounced when the fraction of youngest reticulocytes after buoyant density separation in a serum albumin gradient was used, whereas the cells of medium density failed to show the intermittent increase. The lipoxygenase activity was largely paralleled by the amount of lipoxygenase protein. The increase of lipoxygenase was prevented by either anaerobiosis or addition of oligomycin. The protein synthesis was greatly decreased after 4 h of incubation. The decline of the amount of lipoxygenase between 4 and 24 h incubation is probably largely caused by proteolysis. The results support former interpretations as to the synthesis and biological dynamics of lipoxygenase in reticulocytes.
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PMID:In vitro maturation of rabbit reticulocytes. III. Response of lipoxygenase. 642 28

When human monocytes or alveolar macrophages are cultured in the presence of interleukin (IL)-4 or IL-13, the expression of the reticulocyte-type 15-lipoxygenase is induced. In mice a 15-lipoxygenase is not expressed, but a leukocyte-type 12-lipoxygenase is present in peritoneal macrophages. To investigate whether both lipoxygenase isoforms exhibit a similar regulatory response toward cytokine stimulation, we studied the regulation of the leukocyte-type 12-lipoxygenase of murine peritoneal macrophages by interleukins and found that the activity of this enzyme is upregulated in a dose-dependent manner when the cells were cultured in the presence of the IL-4 or IL-13 but not by IL-10. When peripheral murine monocytes that do not express the lipoxygenase were treated with IL-4 expression of 12/15-lipoxygenase mRNA was induced, suggesting pretranslational control mechanisms. In contrast, no upregulation of the lipoxygenase activity was observed when the macrophages were prepared from homozygous STAT6-deficient mice. Peritoneal macrophages of transgenic mice that systemically overexpress IL-4 exhibited a threefold to fourfold higher 12-lipoxygenase activity than cells prepared from control animals. A similar upregulation of 12-lipoxygenase activity was detected in heart, spleen, and lung of the transgenic animals. Moreover, a strong induction of the enzyme was observed in red cells during experimental anemia in mice. The data presented here indicate that (1) the 12-lipoxygenase activity of murine macrophages is upregulated in vitro and in vivo by IL-4 and/or IL-13, (2) this upregulation requires expression of the transcription factor STAT6, and (3) the constitutive expression of the enzyme appears to be STAT6 independent. The cytokine-dependent upregulation of the murine macrophage 12-lipoxygenase and its induction during experimental anemia suggests its close relatedness with the human reticulocyte-type 15-lipoxygenase despite their differences in the positional specificity of arachidonic acid oxygenation.
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PMID:Interleukin-4 and -13 induce upregulation of the murine macrophage 12/15-lipoxygenase activity: evidence for the involvement of transcription factor STAT6. 974 91

Development of further diagnostic and prognostic tools in myelodysplastic syndromes (MDS) is warranted. In this study we tested two molecular markers in bone marrow of MDS patients: Galpha16, a hematopoiesis-specific G protein alpha subunit serving as an intracellular marker of hematopoietic activity, and 5'-lipoxygenase (5-LO), a putative differentiation marker. The results were correlated with clinical and laboratory features and outcome. Bone marrow mononuclear cells were evaluated by block cycler PCR in 32 patients for Galpha16 and in 25 patients for 5-LO. In 12 patients cDNA analyzed by the block cycler method was quantified by real-time quantitative (RTQ) PCR for both Galpha16 and 5-LO. The results confirmed concordance of the two methods. All FAB and WHO subtypes were positive for at least one of the two genes. Strikingly, only 1 of 11 patients with refractory anemia with ringed sideroblasts was positive for Galpha16. No correlation between Galpha16 or 5-LO and bone marrow cellularity or cytogenetic risk factors (IPSS) was detected. Only combined evaluation of Galpha16 and 5-LO expression showed a correlation with extent of anemia and thrombocytopenia. A relationship between the two markers and preleukemic duration was found. Our findings show that both Galpha16 and 5-LO can be expressed in MDS, reflecting proliferation and differentiation processes in this disease. Different expression patterns of the two molecules indicate that proliferation and differentiation of hematopoietic cells may occur independently. These parameters could constitute a new class of risk factors in MDS. Determination of Galpha16 and 5-LO expression may provide a tool for observing growth and maturation in these diseases.
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PMID:Assessment of growth and differentiation processes in myelodysplastic syndromes by PCR analysis of Galpha16 and 5'-lipoxygenase. 1245 1


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