G. Tóth

Interaction of casein with human polymorphonuclear cells

Attachment of 125I-casein to PMN cells was investigated. Iodination did not decrease the chemotactic effect of casein. 125I-casein binding was increasing toward a maximum reached at about 45 min at 24, and 37 degrees C. At 4 degrees C the binding was proportional to time for 45 min. No saturation was achieved even at 15 mg/ml casein. About 40% of casein remained attached to PMN in a casein-free medium after 60 min, at 37 degrees C. Pretreatment of the cells with trypsin or butanol, or the presence of indomethacin, azide, and PMSF did not affect the binding of casein. The hydrophobic amino acid, leucin counteracted the attachment of casein. Our data show that at chemotactic doses casein is bound specifically to cell membranes by hydrophobic forces. The induction of chemotaxis may be due to micellar casein-membrane lipid complexes.

Removal of Silver Traces from Palladium by Means of Selective Adsorption

A highly effective method has been developed for the separation of silver traces from palladium based on the selective adsorption of the former on platinum surface. Authors separated 97 per cent of silver traces labelled with Ag111 from palladium with the initial silver-palladium weight ratio being 10−8. The silver separated proved to be chemically free from palladium. Influence of the preliminary treatment of platinum on its adsorption capacity has been studied.

ADSORPTION CHROMATOGRAPHIC SEPARATION OF RADIOIODINE LABELLED IODOTHYRONINES

Abstract3,3′-diiodothyronine, 3,3′,5-triiodothyronine, 3,3′,5′-triiodothyronine and thyroxine was labelled with125I and/or131I by the use of the chloramine T method.1.2 The labelled products were separated by adsorption chromatography using Sephadex LH-20 dextrangel as adsorbent and aqueous solution of ethanol as eluent.

On the heterogeneity of125I-labelled proteins used as tracers in radioimmunoassay

The distribution of mono- poly- and unlabelled protein molecules in the radiolabelling mixture was calculated from probability point of view as a function of the radioiodine/protein ratio.

The effect of the pH and solvent concentration on the adsorption chromatographic separation of125I-labelled iodotyrosines

Abstract125I-labelled 3-iodo- and 3,5-diiodotyrosine were separated by adsorption chromatography using Sephadex LH-20 dextran gel and ethanol-water binary eluent. The effect of the pH on the distribution coefficient vs. ethanol concentration relationship was determined and interpreted.

A general approach to the chromatographic behaviour of125I-labelled iodothyronines and tyrosine methyl ester derivatives of steroids

The separation of low molecular weight compounds labelled with125I has gained importance with the advent of radioimmunoassay (RIA) in which overwhelmingly125I-labelled analytes are used as tracers. The chloramine T labelling method proved to be the most suitable procedure to introduce radioiodine atom via aromatic electrophilic substitution either in the thyronine molecule or in the tyrosine methyl ester (TME) side chain coupled as a prosthetic group to different compounds which do not possess phenolic hydroxyl groups.

On the heterogeneous isotopic exchange between iodine adsorbed on rhodium and some alkyl iodides

The kinetics of isotopie exchange between iodine adsorbed on rhodium and methyl, ethyl, η-propyl and η-butyl iodide was investigated. It was found that the time dependence of the fraction exchange ( 1 F ) varies with time similarly as it does in an aqueous solution of I J ions. The minimum activation energy of the exchange (i.e¿ the activation energy for the least firmly bound adsorbed iodine atoms) was calculated from an Arrhenius plot. As expected, the activation energies were considerably lower than those for the corresponding homogeneous exchange processes, which can be explained by the fact that the iodine of the adsorbed monolayer is already in atomic state, thereby saving the 36 kcal/mole dissociation it requires in most solvents.

Effect of the specific activity of the tracer on rat luteinizing hormone radioimmunoassay

Rat luteinizing hormone /LH/ was labelled with125I by the Chloramine T method.125I-LH, used as tracer in radioimmunoassay, was separated from the labelling reaction mixture by gel filtration. By using the proper protein/radioiodine ratio in the labelling reaction mixture the specific activity of125I-LH was adjusted to 2.5–20.5 MBq μg−1. The influence of the specific activity on the assay parameters as well as on the tracer stability was investigated.

Did we catch the point of the immunoassay principle correctly

The present study was aimed at examining the degree of saturation of antibody in immunoassay. The results show that in equilibrium type immunoassay antibody is not fully occupied by antigen at any virtual point of the calibration curve since antibody saturation would lead to B/F=0. Calculations suggest that in an immunoassay meeting the condition p*→0 both relationships between antigen (p) and antibody (q) concentrations can be found (i.e. pq). This is probably generally valid for any assay independently of the experimental technique and tracer used when a fixed amount of binder (antibody, receptor, etc.) is used for the analysis of a binding substance (antigen, ligand, etc.), and the proportion of their interaction is evaluated. Also, the appropriateness of the terms “saturation analysis” and “limited and/or excess reagent” assay for immunoassay is discussed.

Direct determination of urinary 6-keto-prostaglandin-F1α by a new radioimmunoassay method

Clinical testing of a new RIA kit for the determination of 6-keto-prostaglandin F1α (6-keto-PGF1α) has been performed. The statistical characteristics of the calibration curves, the intra- and interassay variation coefficients and the recovery studies point to the reliability and applicability of this test. Using this test. Using this RIA-kit, the urinary 6-keto-PGF1α content could be detected without applying a prior extraction procedure and chromatography, and the results obtained (urinary excretion of 6-keto-PFG1α of control subjects and of patients with chronic glomerular diseases) corresponded well with various other methods.