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F D Lasky

Publications and source records attributed to F D Lasky.

8 recordsLinked to original sources
PubMed1992

Proficiency testing linked to the national reference system for the clinical laboratory: a proposal for achieving accuracy.

I propose using proficiency testing (PT) to achieve one of the important goals of CLIA: accurate and reliable clinical testing. Routine methods for the clinical laboratory are traceable to Definitive (DM) or Reference Methods (RM) or to Methodological Principles (MP) through a modification of the National Reference System for the Clinical Laboratory. PT is the link used to monitor consistent field performance. Although PT has been effective as a relative measure of laboratory performance, the technical limitations of PT fluids and of routine methods currently in use make it unlikely that PT alone can be used as a reliable measure of laboratory accuracy. Instead, I recommend calibration of routine systems through correlation to DM, RM, or MP with use of patients' specimens. The manufacturer is in the best position to assume this responsibility because of also being responsible for consistent, reliable product. Analysis of different manufactured batches of reagent would be compared with predetermined goals for precision and accuracy, as illustrated with data from product testing of Kodak Ektachem clinical chemistry slides. Adoption of this proposal would give manufacturers of PT materials, manufacturers of analytical systems, PT providers, and government agencies time to understand and resolve sources of error that limit the utility of PT for the job required by law.

Chemistry, Clinical↗
PubMed1978

Improved approach to sequential addition immunoassay.

In the usual sequential addition enzyme immunoassays for drugs, the activity of the drug-labeled enzyme decreases continuously with time as more of it is bound to antibody. Sensitivity also decreases; the activity immediately after mixing is the most sensitive indicator of drug concentration. The reaction of enzyme-drug with antibody can be stopped by saturating the antibody with a larger quantity of unlabeled drug, which reacts with the antibody faster than does the enzyme-labeled drug. When drug is added soon after the reaction starts, the enzyme activity is stabilized and the sensitivity to small quantities of antigen is increased. This approach, with modification, should be applicable to sequential immunoassays in which other kinds of labels are used. The enzyme activity can be measured for a longer time, with the predictable increase in precision, as well as the ability to detect smaller quantities, to use less reagent, and to use end-point rather than kinetic assays.

Antigen-Antibody Reactions↗
PubMed1977

Enzyme immunoassays with the miniature centrifugal fast analyzer.

We studied the EMIT (Enzyme Multiplied Immunoassay Technique, Syva) procedures for the assay of phenytoin and phenobarbital in serum, adapting them to the miniature Centrifugal Fast Analyzer. For different concentrations of drug, each rate of reaction decreased continuously with time, tending to converge on a single common value. The rate was most affected by the concentration of drug almost immediately after the reagents were mixed, less so thereafter. The antibody evidently is present in sufficient excess to bind all the enzyme-labeled drug ordinarily present, but the antibody-bound enzyme was only 75% inhibited; this helps explain the appreciable residual activity when no drug is present. The reaction course was the same whether the serum and enzyme-labeled drug were added to the antibody sequentially or simultaneously, which suggests that antibody is bound to drug appreciably faster than to enzyme-labeled drug. The reaction rates 15 to 30 s after mixing were used as the measure of the drug concentrations. These results were confirmed by noting the rates at successive 15-s intervals. The analyzer yielded a run-to-run CV of 10% for phenobarbital at 30 mg/liter, and 9% for phenytoin at 15 mg/liter, as compared to the 15% quoted by Syva.

Centrifugation↗
PubMed1976

Chelate mediated transfer of iron from transferrin to desferrioxamine.

Desferrioxamine, widely used for the treatment of iron overload in Cooley's anaemia, binds iron so tightly that it should quantitatively remove iron from transferrin. Studies conducted in vivo and in vitro, however, have failed to demonstrate significant depletion of transferrin-bound iron by a stoichiometric excess of desferrioxamine. However, low molecular weight chelating agents, capable of forming ternary complexes with transferrin and ferric iron, can promote a rapid transfer of iron from transferrin to desferrioxamine. A possible mechanism for this facilitated exchange is offered.

Chelating Agents↗
PubMed1976

A new iron-binding protein isolated from intestinal mucosa.

A new iron-binding protein contained in guinea pig intestinal mucosa has been purified to homogeneity. The protein has a molecular weight of 78,000 in a nondissociating system and 43,000 in SDS-gel electrophoresis. It binds approximately 2 moles of iron per mole with a formation constant of 10(19) at pH 7. It is distinguished from transferrin and lactoferrin by differences on DEAE-Sephadex chromatography and spectroscopy and by its failure to cross-react with antisera to these other iron-binding proteins.

Animals↗