Abstract: Photochromic ink comprising a spiroheterocycle or metal dithiozonate photochromic dye.

Abstract: Method for determining the presence of an aminotransferase (AT.sub.1), other than aspartate aminotransferase (AST), in a biological sample. The method includes contacting the sample with an amino donor substrate for AT.sub.1, an amino acceptor substrate for AT.sub.1, cysteine sulfinic acid (CSA) in excess, a second aminotransferase (AT.sub.2), different from AT.sub.1, in excess, and an indicator for the presence of sulfite ions, under conditions in which the concentration of said AT.sub.1 can be determined by the amount of the indicator which forms a detectable signal.

Abstract: A radioassay procedure and reagent kit therefor for detecting auto blocking antibody, such as auto blocking antibody which interferes with the complexation of intrinsic factor with vitamin B.sub.12. A receptor, i.e., intrinsic factor, is immobilized on a support and the amount of ligand, i.e., vitamin B.sub.12, capable of binding therewith in the presence of a biological fluid sample is determined.

Abstract: An improved radiometric assay of dialysates from equilibrium dialysis procedures which involves using immobilized antibody specific for a given hapten to separate free hapten (including radiolabeled hapten) from radiolabeled non-hapten breakdown products.

Abstract: Creatine kinase isoenzymes in a liquid sample are determined by means of immobilized antibody-isoenzyme complexes in which measureable isoenzyme activity is retained.

Abstract: A method for detecting the presence of Neisseria bacteria in a fluid sample which comprises bringing immobilized antibody specific for the enzyme 1,2-propanediol dehydrogenase which is released from such bacteria upon lysis thereof, into contact with a lysed sample, isolating the immobilized antibody or resulting immobilized antibody-enzyme complex or mixture thereof, and then testing the isolated material for enzymatic activity.

Abstract: This invention relates to a method for isolating platelets, lymphocytes, and monocytes from anticoagulated blood. The method involves centrifuging at high force a sample of uncoagulated blood with a water-insoluble thixotropic gel-like material having a specific gravity between 1.065-1.077 g/cc for a length of time sufficient to cause the gel-like material to form a barrier between the platelets, lymphocytes, monocytes, and plasma fraction of the blood and the heavier blood cells. Thereafter, the plasma is withdrawn and the platelets, lymphocytes, and monocytes removed from above the barrier in a buffer solution. Where desired, the platelets can be separated from the lymphocytes and monocytes utilizing a similar process but wherein the water-insoluble thixotropic gel-like material has a specific gravity of less than about 1.055 g/cc.

Abstract: Method of determining the concentration of thyroxine binding globulin (TBG) in a fluid sample. The method comprises the steps of adding to the sample an excess amount of thyroxine (T.sub.4) and then analyzing the sample for T.sub.4 via immunoassay technique in the presence and absence of a blocking agent to establish a binding differential. The differential is then correlated with a standard curve which relates known TBG concentrations to binding differentials obtained in a similar manner.

Abstract: Method for determining the concentration of free (unbound) thyroid hormones (T.sub.3 or T.sub.4) in a fluid sample. The method comprises the steps of performing an immunoassay for total T.sub.3 or total T.sub.4 in the presence and absence of a blocking agent to establish a binding differential and then correlating that differential with a standard curve which relates known free thyroid hormone concentrations with binding differentials.

Abstract: Proteins such as enzymes or antibodies can be immobilized in a biologically active state on various inorganic supports via an intermediate residue of o-dianisidine.