Abstract: A process for the determination of peroxidase activity or hydrogen peroxide in a clinical sample colorometrically by adding to the sample a reduced form coenzyme, a reagent selected from amines, phenols, and naphthols, a compound which is colored in the reduced form, and peroxidase or an aqueous solution of hydrogen peroxide. The process is essentially unaffected by the presence of ascorbic acid, bilirubin or other reducing substances of body fluids.

Abstract: A conjugate having cytotoxicity prepared by covalently binding a polymer which has cytotoxic substances linked to its side chains and a reactive group at its terminal to an immunoglobulin, or its fragment, which is capable of selectively binding to a particular antigen possessed by cells to be killed.

Abstract: Antitumor protein hybrid, having a moiety consisting of the antitumor immunoglobulin and a moiety substantially consisting of the fragment A of a diphtheria toxin, which is expressed by the following formula (I):Ab(NHCO--X--S.sub.1 --S.sub.2 --FA).sub.n (I)(where Ab indicates a moiety consisting of the antitumor immunoglobulin and FA indicates a moiety substantially consisting of the fragment A of a diphtheria toxin; X is an alkylene group or phenylene group which either has or does not have a branching of 1 to 5 carbon atoms. N in the amido bond is a nitrogen atom arising from the amino group in the antitumor immunoglobulin; S.sub.1 and S.sub.2 are both sulfur atoms, S.sub.2 indicating a sulfur atom arising from the disulfide bond in a diphtheria toxin; n stands for an integer of 1 to 5).This antitumor protein hybrid has remarkable and specific citotoxicity against tumor cells.

Abstract: Antitumor protein hybrid, composed of a moiety which is substantially the fragment Fab of an anti-.alpha.-fetoprotein antibody and a moiety which is substantially the fragment A of a diphtheria toxin, which is expressed by the following formula (I):Fab--(S.sub.1 --(X).sub.n --S.sub.2 --FA).sub.m (I)(where Fab indicates a moiety which is substantially the fragment Fab of an anti-.alpha.-fetoprotein antibody; FA indicates a moiety which is substantially the fragment A of diphtheria toxin; X indicates a divalent organic radical; S.sub.1 and S.sub.2 are both sulfur atoms, S.sub.1 indicating a sulfur atom arising from the disulfide bond (--S--S--bond) in an anti-.alpha.-fetoprotein antibody and S.sub.2 a sulfur atom arising from the disulfide bond in a diphtheria toxin; n stands for 0 or 1 and m stands for an integer of 1 to 5). This antitumor protein hybrid has remarkable and specific citotoxicity against tumor cells.

Abstract: A method and composition for detecting an antigenic substance by immunodiffusion using an antigenic substance to be detected labeled by a chromogenic enzyme. According to the method and the detection material of this invention, even a small amount of an antigenic substance can be easily detected.