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  • 1990-1994  (4)
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  • 1
    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.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
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  • 2
    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.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    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.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    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.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
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