Biomedical subjects

S T Agnese

Publications and source records attributed to S T Agnese.

4 recordsLinked to original sources

PubMed1983

Evaluation of four reagents for delipidation of serum.

Four reagents, Aerosil 380, Freon 113, Dextran sulfate 500-S, and a mixed organic solvent were tested for their abilities to produce optically clear, pooled human serum. Aerosil-380, a silicon dioxide, removed 95% of serum cholesterol and triglycerides, and 80% of the free fatty acids. A mixed organic solvent (n-butanol:diisopropyl ether) was equally effective, but also removed nearly all endogenous alkaline phosphatase and lactate dehydrogenase. Freon-113 and Dextran sulfate 500-S removed about half of the serum cholesterol and triglycerides. The serum content of several non-lipid components was unaffected by Aerosil-380, Freon-113, and Dextran sulfate treatments; however, the mixed organic solvent removed 69% of the endogenous calcium. Light scattering data revealed that treatment with all reagents except the mixed organic solvent resulted in optically-clear serum products.

Blood Chemical Analysis↗

PubMed1977

Linearization of data for saturation-type competitive protein binding assay and radioimmunoassay.

Most of the commonly-performed competitive protein-binding radioassay methods utilized in the clinical laboratory are based on the principle of saturation analysis. Although many different methods for linearization of saturation-type assays have been proposed, the algebraic equivalency of all of these methods has not been adequately documented. In this manuscript we have shown the physical and mathematical basis for various methods for linearlization of saturation type assays and the algebraic equivalency of these linearization methods. We have also shown that key parameters such as slope and intercept may be dependent on different components of the assays system with differnt linearization methods. An understanding of these key parameters can help the analyst to evaluate changes in these key parameters and to integrate these parameters in a complete quality control system.

Binding, Competitive↗

PubMed1976

Optimization of T assay: a model study.

Factors involved in the optimization of competitive binding radioassays have been analyzed using a thyroxine (T4) radioassay as a model system. The effects of kinetic errors are minimized by the use of the lowest possible incubation temperature for the separation step and by the use of labeled T4 of high purity (which is not consistently available from commerical sources). The use of labeled T4 containing significant quantities of labeled triiodothyronine (T3) can lead to a marked increase in bias and a decrease in precision with relatively small errors in the separation step due to the relatively short half-life of the T3-binder complex. The determination of the dissociation rate constant (not to be confused with the affinity constant) allows one to make useful estimates of the tolerances that can be allowed in the separation step in order to achieve a desired level of accuracy and precison.

Evaluation Studies as Topic↗

PubMed1976

An evaluation of three commercially prepared anion-exchange resin columns for separation of tetraiodothryonine in serum.

Three different commercially prepared anion-exchange resin columns for thyroxine (T4) separation from serum for the "T4 by column" assay were evaluated using the protocol of the supplier. The claims by the suppliers for the distribution and recovery of T4 in the first and second thyroxine-containing eluates were experimentally evaluated by the addition of a tracer quantity of purified [125I]T4. The average experimentally determined elution ratios of recoverable T4 (sum of T4 in first and second eluates) with these commercial columns were: Bio-Rad, 92.2:7.8 (90:10 claimed); Oxford, 87.8:12.2 (94:6 claimed); and Curtis Nuclear, 88.7:11.3 (80:20 claimed). The percent recoveries of T4 in the first thyroxine-containing eluate were: Oxford, 82.3 + 9.70 (x +/- 1 S.D.); Bio-Rad, 91.75 +/- 2.09; and Curtis Nuclear, 74.20 +/- 6.14. Mean serum T4 values obtained by the column method with all commercial columns tested were lower than competitive protein binding radio-assay (CPBR) values if the former values were not corrected for recovery. When individual recovery correction factors were applied to column results, improved correlation and better correspondence of "T4 by column" mean values with the CPBR values were noted. It is concluded that the largest part of the total variability of the "T4 by column" assay is contributed by the chromatographic step when the colorimetric step is performed with an automated technique.

Anion Exchange Resins↗