scholarly journals The Determination of Erythrocyte Folate Concentration Using a Two-Phase Ligand-binding Radioassay

Blood ◽  
1974 ◽  
Vol 43 (3) ◽  
pp. 437-443 ◽  
Author(s):  
Sheldon P. Rothenberg ◽  
Maria da Costa ◽  
John Lawson ◽  
Zoltan Rosenberg
Keyword(s):  
Ligand Binding ◽  
Lactobacillus Casei ◽  
Normal Subjects ◽  
Normal Serum ◽  
Serum Folate ◽  
Two Phase ◽  
Folate Concentration ◽  
Erythrocyte Folate ◽  
The Mean

Abstract The concentration of folate in erythrocytes was determined using a two-phase ligand-binding radioassay procedure described previously for measuring serum folate. The mean (± SD) folate concentration in erythrocytes of 20 normal subjects was 210 ± 57 ng/ml. In 12 patients clinically folate deficient who had normal serum B12 concentration, the mean (± SD) erythrocyte folate was 71 ± 39 ng/ml. Incubation of the lysed erythrocytes for 2 hr prior to boiling increased the radioassayable folate. The radioassayable folate decreased rapidly if the whole blood was stored at 4°C without ascorbate. Extracts of blood prepared with ascorbate could be stored at -20°C for several days. The radioassayable concentration of erythrocyte folate was similar to the values obtained using Lactobacillus casei when the concentration was 200 ng/ ml or less. With values higher by L. casei, the radioassayable folate was significantly lower even though the normal and folate-deficient groups were distinctly separated. This radioassay provides a rapid and reliable method of measuring erythrocyte folate, a parameter which reflects folate stores more reliably than serum folate concentration.

Enzyme immunoassay of free thyroxin in dried blood samples on filter paper.

1985 ◽  
Vol 31 (5) ◽  
pp. 750-753 ◽  
Author(s):  
N Hata ◽  
K Miyai ◽  
M Ito ◽  
Y Endo ◽  
Y Iijimi ◽  
...  
Keyword(s):  
Enzyme Immunoassay ◽  
Filter Paper ◽  
Room Temperature ◽  
Normal Subjects ◽  
Blood Samples ◽  
Double Antibody ◽  
Coefficients Of Variation ◽  
The Mean ◽  
Measurable Range

Abstract We describe a double-antibody enzyme immunoassay for determination of free thyroxin (FT4) in dried blood samples on filter paper, with use of a T4-beta-D-galactosidase complex. The measurable range of FT4 concentration in two 3-mm blood discs, each of which contained about 2.7 microL of blood, was 1.9 to 93 ng/L, as determined by comparison with concentrations of FT4 in known serum standards. FT4 in blood samples dried on filter paper was stable for at least four weeks when kept dry at -20 degrees C, room temperature, or 37 degrees C. The mean coefficients of variation were 7.6% (within assay) and 6.4% (between assays). Results for FT4 by this method correlated well with those for serum determined by radioimmunoassay (r = 0.98). The proposed method can be used to differentiate persons with hyper- and hypothyroidism from normal subjects and those with abnormal concentrations of thyroxin-binding globulin. The procedure seems suited for screening studies.

Effect of 1,25-(OH)2D3 on jejunal absorption of magnesium in patients with chronic renal disease

1980 ◽  
Vol 238 (4) ◽  
pp. G349-G352 ◽  
Author(s):  
A. C. Schmulen ◽  
M. Lerman ◽  
C. Y. Pak ◽  
J. Zerwekh ◽  
S. Morawski ◽  
...  
Keyword(s):  
Vitamin D ◽  
Renal Disease ◽  
Chronic Renal Disease ◽  
Normal Subjects ◽  
Mean Value ◽  
Normal Serum ◽  
Perfusion Technique ◽  
Dihydroxyvitamin D3 ◽  
Jejunal Absorption ◽  
The Mean

These studies were performed to see if jejunal malabsorption of magnesium in patients with chronic renal disease was influenced by therapy with 1 alpha, 25-dihydroxyvitamin D3 [1,25-(OH)2D3; 2 microgram/day by mouth for 7 days]. This treatment restored normal serum concentrations of the vitamin D metabolite from 0.9 +/- 0.2 to 4.2 +/- 0.6 ng/dl. Jejunal absorption of magnesium, measured by a triple-lumen constant-perfusion technique, was enhanced in each of the seven patients by this therapy. The mean value rose from 0.04 +/- 0.02 to 0.13 +/- 0.02 mmol . 30 cm-1 . h-1. This last value is similar to the magnesium absorption rate in untreated normal subjects. These results demonstrate that magnesium absorption in the human jejunum is dependent on vitamin D, and they show that 1 alpha,25-dihydroxyvitamin D3 therapy in patients with chronic renal failure is associated with an enhanced jejunal absorption of magnesium.

Towards a mathematical model of limestone pavement vegetation. III. Estimation of the determinants of species frequencies

1970 ◽  
Vol 48 (7) ◽  
pp. 1387-1404 ◽  
Author(s):  
G. A. Yarranton
Keyword(s):  
Mathematical Model ◽  
Multiple Regression ◽  
Two Phase ◽  
Surface Ph ◽  
Expected Frequency ◽  
Species Frequency ◽  
Independent Variables ◽  
The Mean ◽  
Species Frequencies

Models of the determination of the frequencies of 31 species of bryophytes, lichens, and algae in limestone pavement grikes were calculated by multiple regression. Independent variables were parameters of microclimate and surface pH. Percentages of variance accounted for varied from 14 to 72. In most cases the balance is attributable to replicate errors in the estimates of species frequencies and the abundance of zeros in the data. The models were used to predict species frequencies in other grikes, and in most species the mean difference between predicted and observed frequencies was less than 10%. Determinants of species frequency were found to be similar for species growing near the bottoms of the grikes but differed for those occurring near the tops.It is suggested that a two-phase analysis would be more informative than straightforward regression. In phase (a) the conditions under which the expected frequency is nonzero would be delimited; in phase (b) multiple regression would be performed on the observations falling within this region. This proposal is shown to be related to Hutchinson's concepts of fundamental and realized niches. It would also eliminate the problem of the multiple zero.

Redefinition of the Normal Range for Serum Sodium

1968 ◽  
Vol 14 (2) ◽  
pp. 172-178 ◽  
Author(s):  
R B Payne ◽  
M J Levell
Keyword(s):  
Serum Sodium ◽  
Normal Subjects ◽  
Sodium Concentration ◽  
Normal Serum ◽  
Hospital Environment ◽  
Serum Urea ◽  
Water Metabolism ◽  
Normal Range ◽  
The Mean ◽  
A Prospective Study

Abstract The serum sodium concentrations of three groups of patients selected from laboratory records and of one group of outpatients selected for a prospective study were examined. The mean serum sodium concentration of inpatients with normal serum urea concentrations was 8.5 mEq./ L. lower than that of a group of healthy normal subjects. Part of this difference (2.6 mEq./L.) could be attributed to a nonspecific effect of illness. It was not possible to demonstrate any effect due to the hospital environment, but the results do not exclude the possibility of such an effect. It was concluded that all or most of the remaining difference was due to weighting of the inpatient data by low values of pathologic significance; the proportion of these low values was too great to allow a normal range to be extracted from the data by statistical methods. The concept of the normal range is discussed. It is suggested that two ranges are required for serum sodium, a normal range (137-147 mEq./L. in this laboratory) to make assertions about alterations in specific diseases, and a range derived from patients likely to have no manifest disturbances of salt and water metabolism (135-144 mEq./ L.) to detect such disturbances.

Radiochemical method for measuring plasma clearance and urinary excretion of pteroylglutamic acid.

1979 ◽  
Vol 25 (10) ◽  
pp. 1783-1786
Author(s):  
M da Costa ◽  
S P Rothenberg ◽  
Z Rosenberg
Keyword(s):  
Urinary Excretion ◽  
Plasma Clearance ◽  
Normal Subjects ◽  
Serum Folate ◽  
Metabolic Clearance ◽  
Folate Binding Protein ◽  
Radiochemical Method ◽  
Baseline Serum ◽  
Distribution Phase

Abstract A radiochemical procedure is described for specific determination of pteroylglutamate in serum and urine. This method depends on denaturation of methyltetrahydrofolate with peroxide and measurement of the residual folate by a ligand-binding radioassay. The binding determinant for the radioassay is a folate-binding protein, partially purified from chronic myelogenous lekemia cells, that has low affinity for the reduced folates and thus will preferentially measure residual pteroylglutamate rather than any nondenatured residual methyltetrahydrofolate. We used this assay to measure the clearance from plasma and the urinary excretion of pteroylglutamate and a small fraction of serum folate that is stable to this oxidation procedure. The plasma clearance after intravenous injection is characterized by an initial rapid distribution phase followed by a second, slower metabolic phase; after about 2 h all of the administered pteroylglutamate has been cleared from the blood. The peak concentration of total folate in serum 1--2 min after administration of pteroylglutamate exceeded the sum of the endogenous stable and baseline serum folate, indicating that a reduced labile folate was released from the liver and perhaps from other tissues. This reduced folate had a slower metabolic clearance rate and was excreted to some extent in urine. Only 2.3 and 7.9% of the pteroylglutamate administered to two normal subjects was excreted as stable folate.

Determination of the pH of Hemolyzed Packed Red Cells from Arterial Blood

1961 ◽  
Vol 7 (5) ◽  
pp. 536-541 ◽  
Author(s):  
May K Purcell ◽  
Gertrude M Still ◽  
Theodore Rodman ◽  
Henry P Close
Keyword(s):  
Blood Cell ◽  
Normal Subjects ◽  
The Body ◽  
Red Cell ◽  
Arterial Blood ◽  
Fiducial Probability ◽  
The Mean ◽  
Red Cell Ph

Abstract A technic is described for the determination of the in vivo pH of red blood cell hemolysates. The mean arterial red cell pH of 20 normal subjects was 7.19 with a range of 7.15 to 7.22. The fiducial probability at the 0.95 level is 7.13 to 7.25. The mean difference in pH between plasma and cells was 0.21, with a range of 0.15 to 0.23. It is suggested that changes in pH of erythrocytes may reflect changes in other less accessible cells of the body and that the determination may be a useful research and clinical procedure in the study of metabolic and respiratory derangements.

Homocysteine in the Plasma of Renal Transplant Recipients: Effects of Cofactors for Methionine Metabolism

1981 ◽  
Vol 61 (6) ◽  
pp. 743-749 ◽  
Author(s):  
D. E. L. Wilcken ◽  
Vatsala J. Gupta ◽  
A. K. Betts
Keyword(s):  
Folic Acid ◽  
Amino Acid ◽  
Renal Transplant ◽  
Serum Creatinine ◽  
Vitamin B12 ◽  
Normal Subjects ◽  
Serum Folate ◽  
Renal Transplant Recipients ◽  
Transplant Recipients ◽  
Erythrocyte Folate

1. Homocysteine which is formed during the metabolism of methionine is readily oxidized and is measured by the amino acid analyser as cysteine—homocysteine mixed disulphide and homocystine. We measured plasma amino acid concentrations after an overnight fast in 27 stable long-term renal transplant recipients and 25 age-and sex-matched normal subjects with particular emphasis on sulphur-containing amino acids. 2. Plasma cysteine—homocysteine mixed disulphide was increased in the patients (mean 6.0 ± sd 3.2 μmol/l; normal 3.1 ± 0.9 μmol/l, P < 0.001) and homocystine was detectable in low concentration (< 1.0 μmol/l) in 24; the elevation in cysteine—homocysteine was related to serum creatinine (r = 0.60, P < 0.002). Cystine was also increased (91.6 ± 29.3 μmol/l; normal subjects 64.0 ± 16.7 μmol/l, P < 0.001), but methionine concentrations were normal. 3. When pyridoxine, folic acid and vitamin B12, cofactors for homocysteine metabolism, were administered sequentially to 11 arbitrarily selected transplant recipients cysteine—homocysteine decreased from 7.3 ± 2.1 to 4.3 ± 0.8 μmol/l (P < 0.001) and homocystine became undetectable. the response coincided with the giving of folic acid and occurred without alteration in serum creatinine and with normal serum folate and vitamin B12 concentrations. 4. in eight patients in whom pretreatment erythrocyte folate was measured, folic acid therapy reduced cysteine—homocysteine from 9.0 ± 3.1 to 5.4 ± 1.6 μmol/l over a 4 week period (P < 0.001), the largest response being in the one patient with subnormal erythrocyte folate; values were in the low-normal or normal range in the other seven. 5. We conclude that plasma homocysteine is increased in renal transplant recipients when serum creatinine is only moderately elevated and that the homocysteine concentrations are decreased by treatment with folic acid, suggesting that both reduced homocysteine excretion and relative shortages of folic acid are responsible.

scholarly journals Haematological studies on vegans

1978 ◽  
Vol 40 (1) ◽  
pp. 9-15 ◽  
Author(s):  
T. A. B. Sanders ◽  
F. R. Ellis ◽  
J. W. T. Dickerson
Keyword(s):  
Haemoglobin Concentration ◽  
Serum Vitamin ◽  
Mean Value ◽  
Serum Folate ◽  
Vitamin B ◽  
Normal Range ◽  
Blood Formation ◽  
Mean Corpuscular Haemoglobin ◽  
Erythrocyte Folate ◽  
The Mean

1. The concentrations of vitamin B12 and folate in the serum and folate in the erythrocytes were determined and full blood counts made on a series of caucasian vegans and omnivore controls.2. The blood counts and films were normal in all the vegans and no subject had a haemoglobin concentration below the lower limit of normality.3. Although within the normal range, male but not female vegans had lower values for erythrocyte counts and higher values for mean corpuscular volume and mean corpuscular haemoglobin than their controls regardless of whether they were taking vitamin B12 supplements or not.4. The mean serum vitamin B12 concentration was lower in the vegans not taking vitamin B12 supplements and in those using foods supplemented with the vitamin than in the controls, but in no subject was it below 80 ng/l.5. The serum folate concentrations were higher in the vegans than in their controls. The mean value for erythrocyte folate tended to be greater in the vegans not taking vitamin B12 supplements. No subject had an erythrocyte folate concentration of less than 100μg/l.6. It is concluded that megaloblastic anaemia is very rare in caucasian vegans and that a diet consisting entirely of plant foods is generally adequate to promote normal blood formation providing it is composed of a mixture of unrefined cereals, pulses, nuts, fruit and vegetables and is supplemented with vitamin B12.

A Radioassay for Serum Folate: Use of a Two-Phase Sequential-Incubation, Ligand-Binding System

1972 ◽  
Vol 286 (25) ◽  
pp. 1335-1339 ◽  
Author(s):  
Sheldon P. Rothenberg ◽  
Maria daCosta ◽  
Zoltan Rosenberg
Keyword(s):  
Ligand Binding ◽  
Serum Folate ◽  
Two Phase ◽  
Binding System

scholarly journals Total folate binding capacity of normal human plasma, and variations in uremia, cirrhosis, and pregnancy

Blood ◽  
1976 ◽  
Vol 48 (6) ◽  
pp. 911-921 ◽  
Author(s):  
N Colman ◽  
V Herbert
Keyword(s):  
Lactobacillus Casei ◽  
Binding Capacity ◽  
Gel Filtration ◽  
Normal Subjects ◽  
Serum Folate ◽  
Folate Level ◽  
High Affinity ◽  
Serum Folate Level ◽  
Normal Human ◽  
Clinical Conditions

The current study presents evidence that all human serum contains a class of high-affinity folate binders (KA=2.8 X10(10 liters/mole), which migrate as a single peak on gel filtration. Failure of previous studies to detect this characteristic in all but a minority of subjects is attributable to its variable, often total, saturation. Direct measurement of the total folate binding capacity (TFBC) has been made possible by dissociation of endogenous folate-binder complexes at acid pH, removal of free folate by coated charcoal, and radiofolate tagging. This procedure does not appear to significantly denature the binders, which release and rebind similar quantities of 3H-PGA. In 20 normal subjects, TFBC ranged from 100 to 325 pg/ml (mean+/-SE = 174+/-16), and was always at least 33% saturated. In three clinical conditions, all associated with elevated unsaturated folate binding capacity, three different patterns emerged when TFBC was also measured. Uremic subjects had significantly elevated mean TFBC with normal saturation. In cirrhotic subjects, mean TFBC approximated normal, but saturation was significantly decreased. In pregnancy, two groups were seen: one with increased TFBC and the other with a normal TFBC, some of whom had decreased saturation. Lactobacillus casei serum folate level was about 30 times greater than the TFBC; there was no correlation between the two measurements.

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