Binding of labeled thyroxin analog to serum proteins evaluated after radioimmunoassay of free thyroxin.

1989 ◽  
Vol 35 (3) ◽  
pp. 475-477 ◽  
Author(s):  
G Arevalo
Keyword(s):  
Serum Proteins ◽  
Equilibrium Dialysis ◽  
Normal Serum ◽  
Thyroid Status ◽  
Nonthyroidal Illness ◽  
Serum Pool ◽  
Normal Individuals ◽  
Ambulatory Patients ◽  
One Step

Abstract In ambulatory patients, assay of free thyroxin (FT4) in serum correlates well with thyroid status and with results obtained by equilibrium dialysis. The validity of FT4 results has been questioned mainly in euthyroid patients with altered concentrations of thyroid hormone-binding proteins, as in nonthyroidal illness, hereditary analbuminemia, familial dysalbuminemic hyperthyroxinemia (FDH), and the presence of iodothyronine-binding antibodies. I present here a study of the binding of [125I]T4-derivative to serum proteins in the supernate, which is ordinarily discarded after determination of FT4 by one-step radioimmunoassay with dextran-coated charcoal used to separate the free and bound fractions. The results are expressed as a ratio, with results for a normal serum pool as reference. The average ratio was high in hyperthyroid subjects, 1.26 (SD 0.12, n = 25), and in hypoalbuminemia, 1.20 (SD 0.10, n = 15), and low in FDH, 0.62 (SD 0.11, n = 9), and hypothyroid subjects, 0.90 (SD 0.06, n = 20). In normal individuals it was 0.98 (SD 0.05, n = 30). Determination of the analog-binding rate complements the FT4 result and allows for the recognition of cases with abnormal binding by serum proteins, without recourse to other tests recommended for thyroid-function studies.

One-step immunoassays for free (unbound) hormones: the effect of tracer binding by serum proteins.

1986 ◽  
Vol 32 (1) ◽  
pp. 45-49 ◽  
Author(s):  
D Geiseler ◽  
P Chodha ◽  
R Ekins
Keyword(s):  
Serum Proteins ◽  
Single Step ◽  
Assay System ◽  
Measuring System ◽  
Binding Potential ◽  
Protein Distribution ◽  
Analyte Concentration ◽  
Binding Assays ◽  
One Step

Abstract In binding assays for determination of free (non-protein-bound) hormones in serum or plasma, the influence of the measuring system on the original analyte concentration in the sample must be considered. In one- or single-step free-hormone immunoassays, the labeled analyte or analog-tracer not only is bound to the antibody, it also is bound, to some extent, to serum proteins. The dependence of the assay response on two unknown variables--the concentration of free analyte and the binding potential of serum for the tracer--introduces a bias between the actual (original) and measured hormone concentrations. The significance of this protein effect is described by mathematical modeling of the analyte-protein distribution in the assay system. The theoretical consideration is validated by a clearly defined one-step assay system for measurement of free-thyroxin concentration, with a labeled thyroxin-immunoglobulin conjugate used as tracer.

Direct and indirect techniques for free thyroxin compared in patients with nonthyroidal illness. III. Analysis of interference variables by stepwise regression

1990 ◽  
Vol 36 (4) ◽  
pp. 645-650 ◽  
Author(s):  
G Csako ◽  
M H Zweig ◽  
M Ruddel ◽  
J Glickman ◽  
J Kestner
Keyword(s):  
Stepwise Regression ◽  
Equilibrium Dialysis ◽  
Negative Relationship ◽  
Molar Ratio ◽  
Test Results ◽  
Nonthyroidal Illness ◽  
Reverse T3 ◽  
Backward Elimination ◽  
One Step ◽  
Key Variables

Abstract We applied stepwise regression for multivariate analysis of data for free thyroxin (FT4) in serum and for other laboratory tests of thyroid function in patients with nonthyroidal illness. Using the maximum R2 improvement and backward elimination methods to test five variables [prealbumin, albumin, T4-binding globulin (TBG), free fatty acids (FFA), and FFA/albumin molar ratio], we found that the variables with the greatest predictive power clustered according to the methodology of FT4 measurement. Thus, we best predicted the FT4 results obtained by 16 techniques as follows: FT4 measured by one-step (analog) RIAs, with albumin; FT4 determined by two-step (sequential) RIAs, with FFA or FFA/albumin molar ratio; FT4 estimated by a binding-rate-based RIA or conceptually related FT4 indices [based on triiodothyronine (T3) uptake], with TBG; FT4 measured by equilibrium dialysis, with TBG and FFA/albumin molar ratio; and T4/TBG ratios, with either none or prealbumin and albumin. We could very highly (P less than 0.001) predict total T4 and T3 by considering TBG, and total T3 also by considering prealbumin and albumin, whereas reverse T3 was predictable with prealbumin only (negative relationship). We found comparatively weak associations between thyrotropin (TSH) and albumin or TBG. In clinical practice, abnormalities in key variables should call attention to possible effects of these variables on FT4 and other thyroid-test results and thus to the need for appropriate correction or alternative testing.

Direct and indirect techniques for free thyroxin compared in patients with nonthyroidal illness. I. Effect of free fatty acids.

1989 ◽  
Vol 35 (1) ◽  
pp. 102-109 ◽  
Author(s):  
G Csako ◽  
M H Zweig ◽  
J Glickman ◽  
J Kestner ◽  
M Ruddel
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids ◽  
Solid Phase ◽  
Equilibrium Dialysis ◽  
Free Fraction ◽  
Molar Ratio ◽  
Nonthyroidal Illness ◽  
Binding Rate ◽  
Number Of Patients ◽  
One Step

Abstract We examined the effect of endogenous free fatty acids (FFA) on the measurement of free thyroxin (FT4) by five different methodologies represented in 16 different assays in a large number of patients with nonthyroidal illness (NTI). Some, but not all, one-step (analog) FT4 RIAs negatively correlated with FFA concentration. All two-step FT4 RIAs, equilibrium dialysis FT4, and the dialyzable (free) fraction of T4 positively correlated. In contrast, a binding-rate-based FT4 RIA, FT4 indices based on T3 macroaggregated albumin uptake, and T4/TBG ratios did not correlate. We also analyzed the FT4-FFA relationship with a second, more sensitive approach by correlating test results with FFA/albumin molar ratio as an estimate of the "excess" (nonalbumin bound) FFA. We found that all FT4 RIAs, equilibrium dialysis FT4, FT4 indices based on T3 uptake, the dialyzable fraction of labeled T4 in equilibrium dialysis, the fraction of labeled T4 bound to solid phase antibody in the binding-rate-based RIA, and T3 uptake correlated with the FFA/albumin molar ratio. This FFA dependency was comparable among all the various techniques and was relatively small. Thus, increases or decreases in FT4 results due to varying FFA (and albumin) concentrations are highly likely with most currently available methods (only the T4/TBG ratio did not reveal FFA-dependency), but the magnitude of changes varies with the "excess" FFA.

The "ultra-free" ultrafiltration technique compared with equilibrium dialysis for determination of unbound thiopental concentrations in serum.

1981 ◽  
Vol 27 (1) ◽  
pp. 166-168 ◽  
Author(s):  
D Jung ◽  
M Mayersohn ◽  
D Perrier
Keyword(s):  
Room Temperature ◽  
Serum Proteins ◽  
Classical Method ◽  
Equilibrium Dialysis ◽  
Clinical Measurement ◽  
Drug Concentrations ◽  
Significant Difference ◽  
Millipore Membrane ◽  
Total Concentrations

Abstract We compare a new ultrafiltration technique, involving a unique Millipore membrane, with the classical method of equilibrium dialysis for determining the fraction of thiopental not bound to serum proteins. This fraction, as determined by equilibrium dialysis at 37 degrees C, ranged between 12 and 16% for total concentrations at 50 microgram/L to 10 mg/L of serum. In contrast, ultrafiltration at 37 degrees C yielded a 49% higher value for unbound thiopental: 26.3 (SD 2.6)%. Determined at room temperature (24 degrees C), there was no statistically significant difference for results by the two methods: 14.2 and 15.9%, respectively. The discrepancy between results at 37 degrees C may partly be explained by serum proteins penetrating the Ultra-Free filter. For the routine clinical measurement of unbound drug concentrations, the ultrafiltration membrane at room temperature appears to be sufficiently accurate and less time-consuming than equilibrium dialysis.

Direct and indirect techniques for free thyroxin compared in patients with nonthyroidal illness. II. Effect of prealbumin, albumin, and thyroxin-binding globulin.

1989 ◽  
Vol 35 (8) ◽  
pp. 1655-1662 ◽  
Author(s):  
G Csako ◽  
M H Zweig ◽  
J Glickman ◽  
M Ruddel ◽  
J Kestner
Keyword(s):  
Binding Proteins ◽  
Equilibrium Dialysis ◽  
Positive Association ◽  
Blood Collection ◽  
Free T4 ◽  
Nonthyroidal Illness ◽  
Positive Correlation ◽  
Binding Rate ◽  
One Step ◽  
Seriously Ill

Abstract We studied the correlation of thyroxin (T4)-binding proteins with the apparent free T4 (FT4) in 101 patients with nonthyroidal illness (NTI). Most patients (95%) were seriously ill at the time of blood collection. Concentrations of T4-binding prealbumin (transthyretin), albumin, and T4-binding globulin (TBG) often were low in the sera of these patients. Albumin was the most frequently subnormal, TBG the least. FT4 in serum was determined by five methods represented in 16 different assays. With few exceptions, analog (one-step) FT4 RIAs--both the binding-rate-based RIA and the related FT4 indices (calculated from triiodothyronine-macroaggregated albumin uptake and total T4)--and T4/TBG ratios correlated positively and usually highly significantly (P less than 0.01) with concentrations of prealbumin, albumin, and TBG. Equilibrium dialysis values for FT4 did not correlate with prealbumin concentrations but showed a weakly (P less than 0.03) positive association with albumin and a highly significant (P less than 0.002) positive correlation with TBG. Of the three two-step FT4 RIAs tested, the only statistically significant but weakly (P less than 0.02) positive correlation with T4-binding proteins was between Spiria FT4 and TBG. Thus, in these NTI patients, FT4 estimates vary with methodology and, to a lesser extent, with the particular assay used. The results from two-step FT4 RIAs are least associated with binding protein concentrations.

Clinical utility of measuring free thyroxin and free triiodothyronine in serum of critically ill patients by ultrafiltration.

1986 ◽  
Vol 32 (5) ◽  
pp. 797-800 ◽  
Author(s):  
L A Lee ◽  
R A Mooney ◽  
P D Woolf
Keyword(s):  
Critically Ill ◽  
Critically Ill Patients ◽  
Healthy Subjects ◽  
Clinical Utility ◽  
Equilibrium Dialysis ◽  
Reference Population ◽  
Thyroid Status ◽  
Free Triiodothyronine ◽  
One Step ◽  
The Mean

Abstract Free thyroxin (FT4) measurements by ultrafiltration were compared with results obtained by equilibrium dialysis and commercial RIA methods. In a group of critically ill patients, the mean +/- 2 SD FT4 value by ultrafiltration (26.5 +/- 21.4 ng/L) was higher than in the healthy reference population (19.3 +/- 9.8 ng/L, p less than 0.0001), and correlated well with equilibrium dialysis (23.8 +/- 20 ng/L, r = 0.87). By a two-step RIA method (Clinical Assays), the FT4 value was greater in the critically ill (14.7 +/- 9.6 ng/L) than in the reference population (12.8 +/- 5 ng/L, p less than 0.001) and was also correlated with ultrafiltration results (r = 0.71). FT4 values for the ill patients were lower than for the reference population in two one-step RIA methods (Clinical Assays: 8.6 +/- 7.1 ng/L; Corning Medical: 12.7 +/- 9.4 ng/L), neither of which gave results correlated with ultrafiltration (r = 0.16 and 0.22, respectively). The concentration of free triiodothyronine (FT3), also measured by ultrafiltration, was 4.5 +/- 2.2 ng/L in healthy subjects, 12.5 +/- 14.2 ng/L in hyperthyroidism, 1.7 +/- 2.0 ng/L in hypothyroidism, 2.2 +/- 1.9 ng/L in the critically ill subjects, and 3.8 +/- 0.9 ng/L in pregnancy. Thus, FT4 and FT3 measured by ultrafiltration accurately affects assessment of the thyroid status of the patient except in critical illnesses in which FT3 values are indistinguishable from those in hypothyroidism.

Development and Validation of an LC-MS/MS Method for Simultaneous Determination of Canagliflozin and Metformin HCl in Rat Plasma and its Application

2020 ◽  
Vol 16 (6) ◽  
pp. 752-762
Author(s):  
Vivek Nalawade ◽  
Vaibhav A. Dixit ◽  
Amisha Vora ◽  
Himashu Zade
Keyword(s):  
Internal Standard ◽  
Rat Plasma ◽  
Precipitation Method ◽  
Herbal Extracts ◽  
One Step ◽  
Precision And Accuracy ◽  
Development And Validation ◽  
The Impact ◽  
Metformin Hcl

Background: Food and herbal extracts rich in Quercetin (QRT) are often self-medicated by diabetics and can potentially alter the pharmacokinetics (PK) of Metformin HCl (MET) and Canagliflozin (CNG) leading to food or herb-drug interactions and reduced therapeutic efficacy. However, the impact of these flavonoids on the pharmacokinetic behaviour of MET and CNG is mostly unknown. Methods: A simple one-step protein precipitation method was developed for the determination of MET and CNG from rat plasma. The mobile phase chosen was MeOH 65% and 35% water containing 0.1% formic acid at a flow rate of 1mL/min. Results: The retention time of MET, internal standard (Valsartan) and CNG was 1.83, 6.2 and 8.2 min, respectively. The method was found to be linear in the range of 200 - 8000 ng/mL for CNG and 100 = 4000 ng/ml for MET. Precision and accuracy of the method were below 20% at LLOQ and below 15% for LQC, MQC, and HQC. Conclusion: The method was successfully applied for the determination of PK of MET and CNG by using 100 μL of rat plasma. QRT co-administration affects the PK parameters of MET and CNG. This alteration in PK parameters might be of significant use for clinicians and patients.

scholarly journals IMMUNOCHEMICAL RELATION OF BENCE-JONES PROTEINS TO NORMAL SERUM PROTEINS

1955 ◽  
Vol 216 (1) ◽  
pp. 103-111
Author(s):  
H.F. Deutsch ◽  
C.H. Kratochvil ◽  
Arnold E. Reif
Keyword(s):  
Serum Proteins ◽  
Normal Serum ◽  
Bence Jones Proteins

The absence of normal serum proteins in lymphoma patients revealed by disc electrophoresis

1969 ◽  
Vol 25 (7) ◽  
pp. 747-748 ◽  
Author(s):  
S. R. Rohlfing ◽  
E. R. Brown ◽  
S. O. Schwartz ◽  
R. Spira
Keyword(s):  
Serum Proteins ◽  
Disc Electrophoresis ◽  
Normal Serum

scholarly journals Chlorine-Functional Silsesquioxanes (POSS-Cl) as Effective Flame Retardants and Reinforcing Additives for Rigid Polyurethane Foams

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3979
Author(s):  
Anna Strąkowska ◽  
Sylwia Członka ◽  
Karolina Miedzińska ◽  
Krzysztof Strzelec
Keyword(s):  
Flame Retardants ◽  
Elevated Temperatures ◽  
Bending Strength ◽  
Reaction System ◽  
Fire Retardant ◽  
Polyurethane Foams ◽  
Polymerization Reaction ◽  
Three Point Bending ◽  
One Step

The subject of the research was the production of silsesquioxane modified rigid polyurethane (PUR) foams (POSS-Cl) with chlorine functional groups (chlorobenzyl, chloropropyl, chlorobenzylethyl) characterized by reduced flammability. The foams were prepared in a one-step additive polymerization reaction of isocyanates with polyols, and the POSS modifier was added to the reaction system in an amount of 2 wt.% polyol. The influence of POSS was analyzed by performing a series of tests, such as determination of the kinetics of foam growth, determination of apparent density, and structure analysis. Compressive strength, three-point bending strength, hardness, and shape stability at reduced and elevated temperatures were tested, and the hydrophobicity of the surface was determined. The most important measurement was the determination of the thermal stability (TGA) and the flammability of the modified systems using a cone calorimeter. The obtained results, after comparing with the results for unmodified foam, showed a large influence of POSS modifiers on the functional properties, especially thermal and fire-retardant, of the obtained PUR-POSS-Cl systems.

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