Abstract: A method for the determination of the thyroxine-binding index in serum, which method comprises mixing the serum sample to be determined with a defined amount of thyroxine and a defined amount of a determinable enzyme covalently bound to thyroxine, contacting the resulting solution with anti-thyroxine antibodies present in the solid phase, separating the liquid phase from the solid phase, and measuring the activity of said determinable enzyme in one of the phases as a measure of the tyroxine-binding index in said serum sample.

Abstract: New reactive asymmetrical dicarboxylic acid ester compounds of the formula ##STR1## wherein R.sub.1 is an alkyl radical containing up to 3 carbon atoms or is a digoxin or digitoxin residue, R.sub.2 and R.sub.3, which may be the same or different, are alkoxy radicals containing up to 3 carbon atoms or together represent an oxygen atom, X is a cyanomethoxy, succinimide-N-oxy, N-methyl-pyridiniumoxy, 2,4-dinitrophenoxy, 2,4,5-trichlorophenoxy, pentachlorophenoxy, phenylthio, p-nitrophenoxy, p-nitrophenylthio, piperidyl-N-oxy, phthalimido-N-oxy or benztriazol-N-oxy radical and n is 2, 3, 4 or 5, are useful for the preparation of reagents for the investigation of cardiac glycosides (Digitalis glycosides).

Abstract: Process for the preparation of reactive, couplable derivatives of the thyroid hormones 3,3',5-triiodothyronine (T.sub.3) and 3,3',5,5'-tetraiodothyronine (T.sub.4) by reaction with reactive carboxylic acid derivatives, which process comprises sylylating all the functional groups of the thyroid hormone by reaction with a reactive triorganosylyl derivative and then reacting the persylylated derivative of the thyroid hormone thus obtained with an activated carboxylic acid derivative.

Abstract: A method for the determination of creatine kinase-MB in serum by immunological exclusion of sub-unit M and measurement of the sub-unit B for the determination of creatine kinase, the improvement comprising, for the purpose of excluding the sub-unit M, adding to the reaction mixture comprising determination reagents and the creatine kinase-containing sample, monovalent fragments obtained from antibodies against the sub-unit M by proteolytic cleavage under reducing conditions.

Abstract: The present invention provides a method for the determination of peroxidase in the presence of a compound, the enzyme-catalysed oxidation of which with a peroxy compound results in the emission of light, which is measured, wherein 7-dimethylaminonaphthalene-1,2-dicarboxylic acid hydrazide of the formula ##STR1## is used as light-emitting compound. The present invention also provides a reagent for the determination of peroxidase, comprising 7-dimethylaminonaphthalene-1,2-dicarboxylic acid hydrazide, a system providing hydrogen peroxide and a buffer substance of pH 6 to 9.

Abstract: New reactive asymmetrical dicarboxylic acid ester compounds of the formula ##STR1## wherein R.sub.1 is an alkyl radical containing up to 3 carbon atoms or is a digoxin or digitoxin residue, R.sub.2 and R.sub.3, which may be the same or different, are alkoxy radicals containing up to 3 carbon atoms or together represent an oxygen atom, X is a cyanomethoxy, succinimide-N-oxy, N-methyl-pyridiniumoxy, 2,4-dinitrophenoxy, 2,4,5-trichlorophenoxy, pentachlorophenoxy, phenylthio, p-nitrophenoxy, n-nitrophenylthio, piperidyl-N-oxy, phthalimido-N-oxy or benztriazol-N-oxy radical and n is 2, 3, 4 or 5, are useful for the preparation of reagents for the investigation of cardiac glycosides (Digitalis glycosides).

Abstract: Novel alkylolamides of iodizable amino acids of the formula ##STR1## wherein, R.sup.1 is hydroxybenzyl, dihydroxybenzyl or imidazol-4-yl-methyl andR.sup.2 is monohydroxy-alkyl of 1 or 2 carbon atoms or dihydroxy-alkyl of up to 4 carbon atoms,and the water-soluble salts thereof are provided; these materials are useful as components of radioiodizable immune test reagents.

Abstract: New reactive asymmetrical dicarboxylic acid ester compounds of the formula ##STR1## wherein R.sub.1 is an alkyl radical containing up to 3 carbon atoms or is a digoxin or digitoxin residue, R.sub.2 and R.sub.3, which may be the same or different, are alkoxy radicals containing up to 3 carbon atoms or together represent an oxygen atom, X is a cyanomethoxy, succinimide-N-oxy, N-methyl-pyridiniumoxy, 2,4-dinitrophenoxy, 2,4,5-trichlorophenoxy, pentachlorophenoxy, phenylthio, p-nitrophenoxy, p-nitrophenylthio, piperidyl-N-oxy, phthalimido-N-oxy or benztriazol-N-oxy radical and n is 2, 3, 4 or 5. are useful for the preparation of reagents for the investigation of cardiac glycosides (Digitalis glycosides).