Abstract: This invention provides a method for measuring an antigen concentration in a sample, which comprises: preparing VH-domain polypeptide and VL-domain polypeptide of an antibody specific to the antigen; labeling one of the polypeptides with a reporter molecule to form labeled polypeptides, and immobilizing the other polypeptides onto solid-phase to form immobilized polypeptides; contacting the antigen-containing sample and the labeled polypeptides with the solid-phase; and measuring the reporter molecule of the labeled polypeptides bound to the immobilized polypeptides. The present invention permits simpler and quicker sandwich ELISA for measurements of an antigen concentration in high sensitivity.

Abstract: Formation of an intramolecular cross-link in enzyme donor polypeptide fragments of .beta.-galactosidase, thereby forming a cyclic enzyme donor which is hindered from complementation with an enzyme acceptor fragment to form active of .beta.-galactosidase. The cyclic enzyme donor can be linearized by cleaving to restore complementation ability. Assays in which such cyclic enzyme donors are linearized by specific analytes are disclosed, as well as novel homobifunctional bis-maleimido cross-linking agents of the formula ##STR1## wherein R is hydroxy or acetate.

Abstract: Formation of an intramolecular cross-link in enzyme donor polypeptide fragments of .beta.-galactosidase, thereby forming a cyclic enzyme donor which is hindered from complementation with an enzyme acceptor fragment to form active of .beta.-galactosidase. The cyclic enzyme donor can be linearized by cleaving to restore complementation ability. Assays in which such cyclic enzyme donors are linearized by specific analytes are disclosed, as well as novel homobifunctional bis-maleimido cross-linking agents of the formula ##STR1## wherein R is hydroxy or acetate.

Abstract: Diazonium ions which are useful as reagents for the assay of bilirubin content in a sample, such as a body fluid sample, are provided. In one preferred embodiment, 2-methyl-3-nitroaniline diazonium ion is provided, having the structure: ##STR1## Also provided are reagent compositions including the diazonium ions. The reagent compositions may be in liquid or solid form, and further may include other components, such as buffers, carriers, and solubilizers. Salts including the diazonium ion and a counteranion also are provided. Also provided are methods of using the diazonium ions in assays to detect or quantitate bilirubin present in a sample such as a body fluid sample. Using the assays, the amount of direct, indirect, and total bilirubin in a sample may be accurately and reproducibly detected, and optionally correlated with the presence or absence of any of a variety of diseases or disorders of organs such as the liver, gall bladder or intestines.

Abstract: Simplified calibration and improved dose-response linearity of the standard curve of competitive assays are obtained by adding a predetermined amount of unlabeled competitive binding compound (usually just the analyte itself) to a first reagent containing anti-analyte antibodies before the reagent is reacted with a sample containing an unknown amount of analyte.

Abstract: An instrument for determining a characteristic of a biological fluid or a control comprises a radiation-reflective surface, a first source for irradiating the surface, a first detector for detecting radiation reflected from the surface, and a mechanism for determining the characteristic based on the detected radiation. A slide holds a sample of the biological fluid or control the characteristic of which is to be determined. The slide has two opposed walls transparent to the radiation. The first source and first detector are disposed adjacent a first one of the two opposed walls and the radiation reflective surface is disposed adjacent a second of the two opposed walls. A system is provided for supplying power and regulating supplied power from one of multiple power sources to the instrument.

Abstract: A new group of Os(II) and Os(III) compounds useful as redox mediators in electrochemical biosensors. These compounds have 1) low oxidation potential, 2) fast reaction kinetics between the electroactive center of an enzyme and the compound, 3) slow oxidation of osmium by oxygen, and 4) excellent solubility in aqueous medium. These mediators are particularly useful as a component of a reagent used in an electrochemical biosensor, wherein the biosensor is useful for measuring analytes from a biological fluid, such as blood.

Abstract: Novel derivatives of LSD having the formula ##STR1## wherein R.sub.1 is an alkyl, cycloalkyl or aryl group having 1 to 10 carbon atoms, preferably an alkyl group having 1 carbon atom;R.sub.2 is a bond or ##STR2## wherein R.sub.3 is alkyl, cycloalkyl or aryl group having 2 to 10 carbon atoms, preferably an alkyl group having 2 or 5 carbon atoms; Z is an immunogenic carrier substance, an enzyme donor polypeptide or a label selected from the group consisting of an enzyme, a substance having fluorescent or luminescent properties and a radioactive substance; and n is 1 to p where p equals MW of Z/1000. The derivatives include maleimide conjugates of an immunogenic poly(amino acid), an enzyme donor polypeptide or a labeling substance such as an enzyme, a fluorescent substance or a radioactive substance. Novel activated hapten intermediates useful in the preparation of the conjugates and methods for synthesis of the hapten intermediates and their conjugate derivatives are also disclosed.

Abstract: An instrument monitors the coangulation of coagulable fluid blood, blood fraction or a control by combining the coagulable fluid with particles which are affected by a magnetic field so that the particles become suspended relatively freely in the fluid. A time-varying magnetic field causes the particles to be reoriented as the magnetic field varies. The reorientation changes as the fluid coagulates owing to the fluid's changing viscosity. An electromagnet creates the time-varying magnetic field. The electromagnet includes a core comprising a first leg an electrically conductive coil for creating a time-varying magnetic flux in the core, and a return for the time-varying magnetic flux. The first leg and the flux return together comprise a generally H-shaped core of ferromagnetic material. A bobbin is provided on the first leg and the electrically conductive coil is wound on the bobbin.

Abstract: An instrument for determining a characteristic of a biological fluid or a control includes a heater and a heater control. The heater comprises a heater element, supported in heat conducting relationship to the biological fluid or control when the instrument is in use. A temperature sensitive element monitors the temperature of the heater element support. The heater control comprises a first temperature setpoint control for controlling the heater to maintain the temperature of the biological fluid or control at about a first temperature and a second temperature setpoint control for overriding the first temperature setpoint control to heat the biological fluid or control toward a second temperature.

Abstract: An enzyme composition for dissociating tissues is disclosed. The composition comprises purified collagenase I and collagenase II from Clostridium histolyticum in a mass ratio of about 0.3 to 0.6 and a neutral protease such that the ratio of total FITC casein units of activity to Wunsch units of activity in the composition is about 250:1 to about 600:1. The preferred neutral protease is thermolysin.

Abstract: The invention relates to a test system useful in carrying out diagnostic assays. One component of the test system is an unblocked solid phase test carrier with a three dimensional configuration, impregnated with a first binding partner for analyte of interest. The second component of a binding agent containing a second binding partner coupled to an immediately visually determinable label, and a blocking agent. Rapid and accurate assays may be carried out by using the described system.

Abstract: A stable aqueous NAD reagent useful in the measurement of analytes in biological fluids, particularly ethanol and lactate. For the determination of alcohol, the reagent contains alcohol dehydrogenase, pyrazole, NAD, SUTTOCIDE A and an aliphatic, zwitterionic buffer having a secondary or tertiary amine group. Preferred buffers are TAPSO, AMPSO, POPSO, TAPS and DIPSO. For the determination of lactate, the reagent contains lactate dehydrogenase, pyrazole, NAD, SUTTOCIDE A and an aliphatic, zwitterionic buffer having a secondary or tertiary amine group.

Abstract: The invention relates to a method for detection of a specific nucleic acid sequence which comprises forming a reaction mixture by combining(1) a sample suspected of containing a nucleic acid;(2) a probe/enzyme donor polypeptide conjugate comprising(a) an enzyme donor polypeptide sequence comprising a .beta.-galactosidase fragment; and(b) a single-stranded oligonucleotide sequence attached to (a) and capable of hybridizing with said nucleic acid;(3) an enzyme acceptor polypeptide capable of forming an active enzyme upon complementation with said enzyme donor fragment; and(4) a substrate for .beta.-galactosidase; anddetecting hybridization of said probe/enzyme donor conjugate to said sample nucleic acid to form a double strand-specific sequence by determining the amount or rate of enzyme activity on said substrate in said reaction mixture.

Abstract: An instrument for determining a characteristic of a biological fluid or a control comprises a radiation-reflective surface, a first source for irradiating the surface, a first detector for detecting radiation reflected from the surface, and a mechanism for determining the characteristic based on the detected radiation. A slide holds a sample of the biological fluid or control the characteristic of which is to be determined. The slide has two opposed walls transparent to the radiation. The first source and first detector are disposed adjacent a first one of the two opposed walls and the radiation reflective surface is disposed adjacent a second of the two opposed walls. A system is provided for supplying power and regulating supplied power from one of multiple power sources to the instrument.

Abstract: An instrument and a method for determining a characteristic of a biological fluid or control comprise providing a radiation-reflective surface, a source for irradiating the surface, a detector for detecting radiation reflected from the surface, and a cuvette for holding a sample of the biological fluid or control. The cuvette has two opposed walls substantially transparent to the source radiation and reflected radiation. The source and detector are disposed adjacent a first one of the two opposed walls and the radiation reflective surface is disposed adjacent the other wall. The method comprises detecting radiation from the source reflected from the surface using the radiation detector to determine a characteristic of the biological fluid or control.

Abstract: Formation of an intramolecular cross-link in enzyme donor polypeptide fragments of .beta.-galactosidase, thereby forming a cyclic enzyme donor which is hindered from complementation with an enzyme acceptor fragment to form active of .beta.-galactosidase. The cyclic enzyme donor can be linearized by cleaving to restore complementation ability. Assays in which such cyclic enzyme donors are linearized by specific analytes are disclosed, as well as novel homobifunctional bis-maleimido cross-linking agents of the formula ##STR1## wherein R is hydroxy or acetate.

Abstract: An electrochemical biosensor test strip that has a minimum volume blood sample requirement of about 9 microliters. The test strip has working and counter electrodes that are substantially the same size and made of the same electrically conducting material placed on a first insulating substrate. Overlaying the electrodes is a second insulating substrate, which includes a cutout portion that forms a reagent well. The cutout portion exposes a smaller area of the counter electrode than the working electrode. A reagent for analysis of an analyte substantially covers the exposed areas of working and counter electrodes in the reagent well. Overlaying the reagent well and affixed to the second insulating substrate is a spreading mesh that is impregnated with a surfactant. The small cutout portion of 4 millimeters by 4.2 millimeters, small mesh of 6 millimeters by 5.8 millimeters, and small amount of reagent, 4 microliters before drying, allow the test strip to analyze a whole blood sample of about 9 microliters.

Abstract: The present invention relates to a novel method and apparatus for the amperometric determination of an analyte, and in particular, to an apparatus for amperometric analysis utilizing a novel disposable electroanalytical cell for the quantitative determination of biologically important compounds from body fluids.