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  • 1
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    Neutrophils mediate lipid peroxidation in human red cells (1984)
    American Society of Hematology
    Details
    Publication Date: 1984-11-01
    Description: Activated neutrophils (ANs) are known to release reactive oxygen species that may cause oxidative damage to surrounding tissues. We determined if ANs could induce lipid peroxidation (LP) in human red cells and investigated the mechanism involved in this interaction. We studied neonatal glucose-6-phosphate dehydrogenase (G6PD) deficient, and sickle red cells, since each of these are known to be susceptible to oxidant injury. Neutrophils were isolated from whole blood and activated by incubation with opsonized zymosan. Mixtures of such neutrophils and red cells at a ratio of 1:100 were incubated for two hours at 37 degrees C, after which the malonyldialdehyde content in red cells was measured as an index of LP. All red cells underwent LP after AN treatment, and the degree of LP was proportional to the amount of AN in the mixture. Superoxide dismutase and catalase partially inhibited LP. When compared to normal red cells, only sickle cells demonstrated a significant increase in AN-mediated LP. Conversion of hemoglobin to carboxy-hemoglobin increased AN-mediated LP, whereas conversion to met- hemoglobin decreased AN-mediated LP. The protective effect of met- hemoglobin on LP was less in sickle cells than in normal cells. We conclude that AN can induce LP in red cells in vitro and that sickle cells are more susceptible to this process than normal cells. Hemoglobin can serve as an electron trap and protect the cell against peroxidative damage, but this mechanism is impaired in sickle cells. We speculate that the pathogenesis of hemolysis associated with infectious disease may include AN-induced red cell LP.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
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  • 2
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    Neutrophils mediate lipid peroxidation in human red cells (1984)
    American Society of Hematology
    Details
    Publication Date: 1984-11-01
    Description: Activated neutrophils (ANs) are known to release reactive oxygen species that may cause oxidative damage to surrounding tissues. We determined if ANs could induce lipid peroxidation (LP) in human red cells and investigated the mechanism involved in this interaction. We studied neonatal glucose-6-phosphate dehydrogenase (G6PD) deficient, and sickle red cells, since each of these are known to be susceptible to oxidant injury. Neutrophils were isolated from whole blood and activated by incubation with opsonized zymosan. Mixtures of such neutrophils and red cells at a ratio of 1:100 were incubated for two hours at 37 degrees C, after which the malonyldialdehyde content in red cells was measured as an index of LP. All red cells underwent LP after AN treatment, and the degree of LP was proportional to the amount of AN in the mixture. Superoxide dismutase and catalase partially inhibited LP. When compared to normal red cells, only sickle cells demonstrated a significant increase in AN-mediated LP. Conversion of hemoglobin to carboxy-hemoglobin increased AN-mediated LP, whereas conversion to met- hemoglobin decreased AN-mediated LP. The protective effect of met- hemoglobin on LP was less in sickle cells than in normal cells. We conclude that AN can induce LP in red cells in vitro and that sickle cells are more susceptible to this process than normal cells. Hemoglobin can serve as an electron trap and protect the cell against peroxidative damage, but this mechanism is impaired in sickle cells. We speculate that the pathogenesis of hemolysis associated with infectious disease may include AN-induced red cell LP.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
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  • 3
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    Chlorpromazine inhibits vesiculation, alters phosphoinositide turnover and changes deformability of ATP-depleted RBCs (1989)
    American Society of Hematology
    Details
    Publication Date: 1989-05-01
    Description: To delineate further the underlying mechanism by which amphiphilic drugs can modulate vesicle release from human RBCs, we studied the effect of chlorpromazine on erythrocyte vesiculation induced by ATP depletion. This was correlated with turnover of the phosphoinositides as well as RBC deformability during the process since phosphoinositide metabolism may be involved in shape regulation of RBCs. Echinocytic shape transformation and subsequent vesiculation of RBCs, which commonly occur during ATP depletion, were inhibited by chlorpromazine. Furthermore, with a newly developed two-dimensional thin-layer chromatography separation of RBC membrane phospholipids, we showed that chlorpromazine significantly decreased the dephosphorylation of phosphatidylinositol-4,5-bisphosphate (PIP2) in both ATP-depleted RBCs as well as in cells with partly maintained ATP levels. Concomitantly, there was a smaller increase in the relative amount of phosphatidylinositol. In addition, chlorpromazine also inhibited the decreased in RBC deformability as well as the shift of osmotic fragility that occurs during ATP depletion of erythrocytes.
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  • 4
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    Spectrin oxidation correlates with membrane vesiculation in stored RBCs (1987)
    American Society of Hematology
    Details
    Publication Date: 1987-06-01
    Description: An increase in spectrin oxidation in a variety of erythrocytes displaying a tendency to vesiculate has been previously described. To explore this relationship in more detail, we have studied blood stored in citrate-phosphate-dextrose-adenine under blood bank conditions because, in this system, vesiculation occurs slowly. Vesiculation was quantitated by measuring acetylcholinesterase release, and the extent of spectrin oxidation was detected by using thiol-disulfide exchange chromatography. A strong correlation (r = .92) was found between the extent of spectrin oxidation and vesiculation when blood from five donors was analyzed at weekly intervals during storage. This strongly suggests that spectrin oxidation plays a role in the formation of spectrin-free vesicles, thereby limiting the shelf life of stored blood.
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    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
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  • 5
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    Enhancement of erythrocyte superoxide dismutase activity: effects on cellular oxidant defense (1989)
    American Society of Hematology
    Details
    Publication Date: 1989-11-15
    Description: To delineate further the role of superoxide dismutase (SOD) in red blood cell (RBC) oxidant defense, normal human erythrocytes were osmotically lysed and resealed in the presence of varying concentrations of exogenous SOD. This resulted in a dose-dependent increase in SOD activity in the resealed erythrocytes while maintaining nearly normal RBC hemoglobin concentration (less than 10% decrease from the control value), cell volume, and cellular deformability. Surprisingly, a five- or ninefold increase in SOD activity yielded no additional protection against superoxide-generating drugs (phenazine methosulfate or menadione sodium bisulfite). No significant differences were observed between the control and SOD-loaded RBCs in O2-driven methemoglobin formation or generation of thiobarbituric acid-reactive substances. In contrast, RBCs with elevated SOD activity pretreated with sodium azide (to block catalase activity) or 1-chloro-2,4- dinitrobenzene (to deplete reduced glutathione, GSH) showed significantly enhanced methemoglobin generation in response to superoxide generating drugs. No differential response was noted between the control, control-resealed, and SOD-loaded RBCs to oxidants other than superoxide. Based on our results and other data, we conclude that elevated SOD activity may imbalance cellular oxidant defense, resulting in enhanced oxidation due to the accelerated generation of H2O2, the product of O2- dismutation. This effect is significantly exacerbated under conditions in which H2O2 catabolism is altered.
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    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
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  • 6
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    Spectrin oxidation correlates with membrane vesiculation in stored RBCs (1987)
    American Society of Hematology
    Details
    Publication Date: 1987-06-01
    Description: An increase in spectrin oxidation in a variety of erythrocytes displaying a tendency to vesiculate has been previously described. To explore this relationship in more detail, we have studied blood stored in citrate-phosphate-dextrose-adenine under blood bank conditions because, in this system, vesiculation occurs slowly. Vesiculation was quantitated by measuring acetylcholinesterase release, and the extent of spectrin oxidation was detected by using thiol-disulfide exchange chromatography. A strong correlation (r = .92) was found between the extent of spectrin oxidation and vesiculation when blood from five donors was analyzed at weekly intervals during storage. This strongly suggests that spectrin oxidation plays a role in the formation of spectrin-free vesicles, thereby limiting the shelf life of stored blood.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
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  • 7
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    Enhancement of erythrocyte superoxide dismutase activity: effects on cellular oxidant defense (1989)
    American Society of Hematology
    Details
    Publication Date: 1989-11-15
    Description: To delineate further the role of superoxide dismutase (SOD) in red blood cell (RBC) oxidant defense, normal human erythrocytes were osmotically lysed and resealed in the presence of varying concentrations of exogenous SOD. This resulted in a dose-dependent increase in SOD activity in the resealed erythrocytes while maintaining nearly normal RBC hemoglobin concentration (less than 10% decrease from the control value), cell volume, and cellular deformability. Surprisingly, a five- or ninefold increase in SOD activity yielded no additional protection against superoxide-generating drugs (phenazine methosulfate or menadione sodium bisulfite). No significant differences were observed between the control and SOD-loaded RBCs in O2-driven methemoglobin formation or generation of thiobarbituric acid-reactive substances. In contrast, RBCs with elevated SOD activity pretreated with sodium azide (to block catalase activity) or 1-chloro-2,4- dinitrobenzene (to deplete reduced glutathione, GSH) showed significantly enhanced methemoglobin generation in response to superoxide generating drugs. No differential response was noted between the control, control-resealed, and SOD-loaded RBCs to oxidants other than superoxide. Based on our results and other data, we conclude that elevated SOD activity may imbalance cellular oxidant defense, resulting in enhanced oxidation due to the accelerated generation of H2O2, the product of O2- dismutation. This effect is significantly exacerbated under conditions in which H2O2 catabolism is altered.
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    Electronic ISSN: 1528-0020
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    Published by American Society of Hematology
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  • 8
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    NADPH, not glutathione, status modulates oxidant sensitivity in normal and glucose-6-phosphate dehydrogenase-deficient erythrocytes (1991)
    American Society of Hematology
    Details
    Publication Date: 1991-05-01
    Description: Glucose-6-phosphate dehydrogenase (G6PD) deficiency is characterized by the loss of NADPH and enhanced erythrocyte oxidant sensitivity. Historically, it has been theorized that the elevated oxidant sensitivity of G6PD-deficient erythrocytes arises as the direct consequence of decreased intracellular glutathione (GSH) concentrations. To directly investigate the basis of G6PD deficiency oxidant sensitivity, the effects of altered GSH and NADPH concentrations were examined in normal and G6PD-deficient erythrocytes. The results of this study demonstrated that GSH depletion, by 1-chloro- 2,4-dinitrobenzene (CDNB), had no effect on hemoglobin oxidation in response to hydrogen peroxide (H2O2) generating systems (phenazine methosulfate and menadione bisulfite) in either normal or G6PD- deficient cells. Furthermore, a fourfold to sixfold increase in intracellular GSH concentration also did not protect against H2O2- generating systems in the normal or G6PD-deficient erythrocytes. Conversely, introduction of an NADPH-generating system (purified G6PD) into G6PD-deficient cells resulted in a significant decrease in oxidant sensitivity and an ability to cycle GSH. Further experiments demonstrated that the reduced oxidant sensitivity of the G6PD- reconstituted erythrocytes was not due to the maintenance of GSH levels because CDNB-mediated depletion of GSH did not alter this protective effect. Analysis of these results demonstrated a direct correlation between NADPH, but not GSH, concentration and hemoglobin oxidant sensitivity.
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  • 9
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    Molecular characterization of glucose-6-phosphate dehydrogenase (G6PD) deficiency in patients of Chinese descent and identification of new base substitutions in the human G6PD gene (1993)
    American Society of Hematology
    Details
    Publication Date: 1993-04-15
    Description: The underlying DNA changes associated with glucose-6-phosphate dehydrogenase (G6PD)-deficient Asians have not been extensively investigated. To fill this gap, we sequenced the G6PD gene of 43 G6PD- deficient Chinese whose G6PD was well characterized biochemically. DNA samples were obtained from peripheral blood of these individuals for sequencing using a direct polymerase chain reaction (PCR) sequencing procedure. From these 43 samples, we have identified five different types of nucleotide substitutions in the G6PD gene: at cDNA 1388 from G to A (Arg to His); at cDNA 1376 from G to T (Arg to Leu); at cDNA 1024 from C to T (Leu to Phe); at cDNA 392 from G to T (Gly to Val); at cDNA 95 from A to G (His to Arg). These five nucleotide substitutions account for over 83% of our 43 G6PD-deficient samples and these substitutions have not been reported in non-Asians. The substitutions found at cDNA 392 and cDNA 1024 are new findings. The substitutions at cDNA 1376 and 1388 account for over 50% of the 43 samples examined indicating a high prevalence of these two alleles among G6PD-deficient Chinese. Our findings add support to the notion that diverse point mutations may account largely for much of the phenotypic heterogeneity of G6PD deficiency.
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  • 10
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    Enrichment of two glycosyl-phosphatidylinositol-anchored proteins, acetylcholinesterase and decay accelerating factor, in vesicles released from human red blood cells (1989)
    American Society of Hematology
    Details
    Publication Date: 1989-10-01
    Description: Several proteins are attached to the cell membrane by a glycosyl- phosphatidylinositol (GPI) anchor. In this report, we show that during vesiculation of human RBCs in vitro, two of these proteins, acetylcholinesterase and decay accelerating factor, redistribute on the cell surface and become enriched in the released vesicles. As a result, the remnant cells are depleted of these proteins. We suggest that alterations in the architecture of the RBC membrane that precede vesiculation lead to selective polarization of GPI-anchored proteins within the domain of the membrane destined to become a vesicle. Since vesiculation occurs in many cell types, and if the loss of GPI-anchored proteins accompanies this process, it may have important biologic significance.
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    Electronic ISSN: 1528-0020
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