scholarly journals Incubation of NAD(P)H2: glutathione oxidoreductase (EC1.6.4.2) with flavin adenine dinucleotide for maximal stimulation in the measurement of riboflavin status

1982 ◽  
Vol 48 (3) ◽  
pp. 459-466 ◽  
Author(s):  
D. I. Thurnham ◽  
Prapimporn Rathakette
Keyword(s):  
Quality Control ◽  
Glutathione Reductase ◽  
Flavin Adenine Dinucleotide ◽  
Maximal Stimulation ◽  
Maximal Coupling ◽  
Analysis Of Results ◽  
Cusum Analysis ◽  
Activation Coefficient ◽  
Riboflavin Status ◽  
Initial Results

1. Some modifications to the erythrocyte glutathione reductase assay for riboflavin status are described.2. Cusum analysis of results collected on a quality-control (QC) haemolysate, analysedseparately at the beginning and end of each batch of samples over a period of 20 weeks, suggested that the activation coefficient (AC) was higher at the end of a batch than at the beginning.3. The higher AC was due to higher FAD-stimulated enzyme activities of the QC samples measured at the end of the day, by comparison with the beginning, and this suggested that the conditions of assay were not optimal.4. The conditions required to achieve maximal coupling of FAD to glutathione reductase(NAD(P)H2: glutathione oxidoreductase;EC1.6.4.2) were therefore examined and found to be 15 min at 35° by comparison with the 5–7 min incubation used by most workers.5. Alternatively, where samples are prepared in batches, the enzyme and FAD should be pre-incubated in the reaction mixture for 2 h at 4° or 1 h at 25° before the standard incubation of 5 min at 35°.6. Additionally, the use of cummulative sum (cusum) analysis on the QC results suggested that there was a slight deterioration of QC sample after 4-weeks storage. However, theQC results obtained, remained within 2 standard deviations of initial results over a 20-week period, suggesting that the deterioration was very slight.

scholarly journals Effects of methodological variation on assessment of riboflavin status using the erythrocyte glutathione reductase activation coefficient assay

2008 ◽  
Vol 102 (2) ◽  
pp. 273-278 ◽  
Author(s):  
Marilyn H. E. Hill ◽  
Angela Bradley ◽  
Sohail Mushtaq ◽  
Elizabeth A. Williams ◽  
Hilary J. Powers
Keyword(s):  
Glutathione Reductase ◽  
Intervention Study ◽  
Flavin Adenine Dinucleotide ◽  
Riboflavin Deficiency ◽  
Study Results ◽  
Erythrocyte Enzyme ◽  
Activation Coefficient ◽  
The Uk ◽  
Riboflavin Status

Riboflavin status is usually measured as thein vitrostimulation with flavin adenine dinucleotide of the erythrocyte enzyme glutathione reductase, and expressed as an erythrocyte glutathione reductase activation coefficient (EGRAC). This method is used for the National Diet and Nutrition Surveys (NDNS) of the UK. In the period between the 1990 and 2003 surveys of UK adults, the estimated prevalence of riboflavin deficiency, expressed as an EGRAC value ≥ 1·30, increased from 2 to 46 % in males and from 1 to 34 % in females. We hypothesised that subtle but important differences in the detail of the methodology between the two NDNS accounted for this difference. We carried out an evaluation of the performance of the methods used in the two NDNS and compared against an ‘in-house’ method, using blood samples collected from a riboflavin intervention study. Results indicated that the method used for the 1990 NDNS gave a significantly lower mean EGRAC value than both the 2003 NDNS method and the ‘in-house’ method (P < 0·0001). The key differences between the methods relate to the concentration of FAD used in the assay and the duration of the period of incubation of FAD with enzyme. The details of the EGRAC method should be standardised for use in different laboratories and over time. Additionally, it is proposed that consideration be given to re-evaluating the basis of the EGRAC threshold for riboflavin deficiency.

scholarly journals A biochemical evaluation of the erythrocyte glutathione reductase (EC 1.6.4.2) test for riboflavin status

1981 ◽  
Vol 45 (1) ◽  
pp. 53-65 ◽  
Author(s):  
A. M. Prentice ◽  
C. J. Bates
Keyword(s):  
Glutathione Reductase ◽  
Liver Weight ◽  
Strongly Correlated ◽  
Riboflavin Deficiency ◽  
Deficient Diet ◽  
Serial Measurement ◽  
Weanling Rats ◽  
Biochemical Evaluation ◽  
Activation Coefficient ◽  
Riboflavin Status

1. Chronic marginal riboflavin deficiency was induced in groups of weanling rats by feeding a deficient diet supplemented with 0, 0·5, 1·0 and 1·5 mg riboflavin/kg diet. Ad lib.- and pair-fed controls received 3·0 and 15 mg riboflavin/kg diet respectively.2. Serial measurement of erythrocyte NAD(P)H2 glutathione oxidoreductase (glutathione reductase; EC 1.6.4.2) and its activation coefficient revealed that after 12 weeks a steady-state of deficiency had been reached following initial fluctuations in status; the animals were then killed, and their tissues analysed.3. Food intake, growth rate and the appearance of pathological signs were directly proportional to riboflavin content; however relative liver weight was increased above control levels only in the most-severelydeficient group, and anaemia was not detected in any group.4. The activation coefficient of glutathione reductase in erythrocytes and liver was closely related to dietary riboflavin content; that of skin responded maximally even in the least-severelydepleted animals.5. Hepatic and renal flavin contents were directly proportional to dietary riboflavin, FAD being conserved at the expense of ribotlavin and FMN. ATP: riboflavin 5-phosphotransferase (flavokinase; EC 2.7.1.26) activity was reduced, even in the least-severely deficient animals; ATP: FMN adenylyltransferase (FAD pyrophosphory1ase; EC 2.7.7.2) was increased in liver, but only in the most-severely-deficient animals.6. Hepatic succinate: (acceptor) oxidoreductase (succinate dehydrogenase; EC 1. 3.99.1) activity fell sharply between 1·5 and 0·5 mg riboflavin/kg diet, producing an S-shaped dose-response curve; it showed smaller or less specific changes in other tissues such as brain, skin and intestine. NADH: (acceptor) oxidoreductase (NADH dehydrogenase; EC 1.6.99.3) activity declined in liver and intestine, but not in skin or brain.7. Theactivation coefficient of glutathione reductase was correlated strongly with nearly all the riboflavin-sensitive variables measured, once equilibrium had been reached in this chronic deficiency model, and it was particularly strongly correlated with hepatic and renal FAD levels. Under equilibrium conditions, therefore, it appears to represent a good index of the extent of riboflavin deficiency, and significant changes in flavin levels and enzymes in the internal organs were detected even under conditions of marginal deficiency, associated with relatively small increases in the activation coefficient.

scholarly journals Development and Estimation of the Quality Control Program for Breast Ultrasound in Must-Be Trial: Initial Results

2017 ◽  
Vol 43 ◽  
pp. S8-S9
Author(s):  
Hye Won Kim ◽  
Sun Hye Jeong ◽  
You Me Kim ◽  
Keum Won Kim ◽  
Jin Hwa Lee ◽  
...  
Keyword(s):  
Quality Control ◽  
Control Program ◽  
Breast Ultrasound ◽  
Quality Control Program ◽  
Initial Results

Cathode Ray Tube Quality Control and Acceptance Testing Program: Initial Results for Clinical PACS Displays

Radiographics ◽  
2001 ◽  
Vol 21 (3) ◽  
pp. 719-732 ◽  
Author(s):  
Debra S. Groth ◽  
Scott N. Bernatz ◽  
Kenneth A. Fetterly ◽  
Nicholas J. Hangiandreou
Keyword(s):  
Quality Control ◽  
Acceptance Testing ◽  
Testing Program ◽  
Tube Quality ◽  
Cathode Ray Tube ◽  
Initial Results

scholarly journals The Homozygous Hemoglobin EE Variant Is Associated with Poorer Riboflavin Status in Cambodian Women of Reproductive Age

2020 ◽  
Vol 150 (7) ◽  
pp. 1943-1950
Author(s):  
Brock A Williams ◽  
Kelsey M Cochrane ◽  
Jordie A J Fischer ◽  
Abeer M Aljaadi ◽  
Liadhan McAnena ◽  
...  
Keyword(s):  
Geometric Mean ◽  
Linear Regression Analysis ◽  
Venous Blood ◽  
Reproductive Age ◽  
Women Of Reproductive Age ◽  
Hemoglobin E ◽  
Hematological Indices ◽  
Activation Coefficient ◽  
Mean Differences ◽  
Riboflavin Status

ABSTRACT Background Riboflavin is required for erythropoiesis, which is increased in people with hemoglobinopathies due to increased hemolysis and erythrocyte turnover. Dietary intake and status of riboflavin is poor in Cambodia, where hemoglobinopathies are common. Objective We assessed the association between genetic hemoglobin disorders and riboflavin status in women of reproductive age in Cambodia. Methods Venous blood samples from 515 Cambodian women of reproductive age, 18–45 y, were analyzed for biomarker status of riboflavin [erythrocyte glutathione reductase activation coefficient (EGRac)], genetic hemoglobin (Hb) disorders, and hematological indices. Linear regression analysis was used to estimate the association between EGRac with Hb, ferritin, and Hb genotypes. EGRac was log transformed in the analyses, and the regression coefficients represent the geometric mean differences. Results Genetic Hb disorders were present in 57% of the population, with the homozygous hemoglobin E variant (Hb EE) occurring in ∼10% of women (n = 53). Deficient (EGRac ≥1.40) or marginal riboflavin status (EGRac ≥1.30 and &lt;1.40) was observed in 92% (n = 475) of women. The variant Hb EE genotype was associated with 18% (95% CI: 9%, 28%) higher geometric mean EGRac values than the normal Hb AA genotype (P &lt; 0.001). Conclusions Although riboflavin biomarker deficiency or marginal status is widely prevalent in Cambodian women, lower riboflavin status was observed more frequently in women with the Hb EE genotype than in women with normal Hb AA. The relation between genetic Hb disorders and riboflavin warrants further investigation. This trial was registered at clinicaltrials.gov as NCT01593423 and NCT02481375.

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