Abstract: The present invention relates to a method for the determination of cholesterol in low-density lipoprotein (LDL) in a sample containing LDL, which comprises eliminating cholesterol in high-density lipoprotein in the sample, subjecting the sample to a reaction utilizing the action of a cholesterol ester-hydrolyzing enzyme and the action of a cholesterol-oxidizing enzyme or of cholesterol oxidoreductase, and determining the amount of hydrogen peroxide or a reduced type coenzyme generated by the reaction.

Abstract: Disclosed is a chemiluminescent method of quantitatively determining one of peroxide, a peroxidation-active substance or a pyrazolopyridopyridazine derivative represented by the formula (I): ##STR1## wherein R.sup.1 represents hydrogen, lower alkyl, optionally substituted aryl, optionally substituted heterocyclic group, substituted sulfonyl, substituted sulfinyl, substituted thio etc.; R.sup.2 represents hydrogen, lower alkyl, optionally substituted aryl, etc., or a salt thereof; characterized by subjecting an unknown amount of one substance selected from the peroxide, peroxidation-active substance and pyrazolopyridopyridazine derivative to react with a known amount of the remaining two substances.

Abstract: Disclosed is a method for stably storing a liquid diagnostic reagent, comprising air-hermetically keeping the liquid diagnostic reagent in a closed container in the presence of a disoxidant therein. Preferably, at least one of the liquid diagnostic reagent and the disoxidant is covered with a separating container made of a material pervious to oxygen but not to solutions. The liquid diagnostic reagent may comprise an enzyme or an indicator.

Abstract: The present invention relates to a method of quantitative determination of sodium ions in a sample using .beta.-galactosidase, wherein the .beta.-galactosidase reaction is conducted in the presence of at least one chelating agent selected from of 1,2-cyclohexanediamine-N,N,N',N'-tetraacetic acid, ethylenediamine-tetraacetic acid, triethylenetetranine-hexaacetic acid, diethylenetriamine-N,N,N',N",N"-pentaacetic acid, 1,3 -diminopropan-2-ol-N,N',N'-tetraacetic acid, ethylenediamine-N,N'-dipropionic acid dihydrochloride, ethylenediamine-tetrakis(methylenesulfonic acid), iminodiacetic acid, hydroxyimino-diacetic acid and nitrilotriacetic acid.The method of quantitative determination of sodium ions of the present invention is useful in clinical examinations and the accuracy in the measurement by the method is high.

Abstract: Provided are a method of determining the amount of cholesterol in high-density lipoprotein (HDL), which comprises measuring the amount of cholesterol in low-density lipoprotein (LDL), very-low-density lipoprotein (VLDL) and chylomicron (CM) in a sample in the presence of a sugar compound and/or a protein solubilizing agent, and calculating the difference between the amount of cholesterol in LDL, VLDL and CM and the total amount of cholesterol in the sample, and a method of determining the amount of cholesterol in HDL, which comprises measuring the amount of cholesterol in HDL in a sample in the presence of a sugar compound and/or a protein solubilizing agent.

Abstract: A method for stabilizing urease in an assay reagent for determination of urea nitrogen in a sample and a method for accurately determining urea nitrogen in a sample are disclosed. After urea nitrogen in the sample is reacted with urease in the presence of an organic boron compound, the amount of ammonia formed by the reaction is determined.

Abstract: The present invention relates to a method for quantitatively determining potassium ions in a sample using a glycerol dehydrogenase, which method is characterized by pretreating said sample with a glutamine synthetase in the presence of glutamic acid and adenosine triphosphate.

Abstract: The present invention relates to a method for quantitatively determining sodium ions in a sample using .beta.-galactosidase in an aqueous medium, wherein a .beta.-galactosidase reaction is carried out in the presence of a cation which competes with the sodium ion.The method of the present invention is good in accurate determination and reproducibility and enables the simple and quick quantitative determination of sodium ions.

Abstract: Provided is a method of determining the amount of cholesterol in high-density lipoprotein (HDL), which comprises reacting an HDL-containing sample with cholesterol esterase and cholesterol oxidase or cholesterol dehydrogenase in the presence of a reagent for aggregating lipoproteins except HDL, and determining the amount of hydrogen peroxide or reductive co-enzyme formed therein.

Abstract: The present invention provides a new analytical method that an antigen, an antibody or a nucleic acid can be assayed at a high sensitivity in the immunoassay.The present invention provides a method for assaying a substance which comprises the steps of (a) reacting an antigen, an antibody or a nucleic acid which is the substance to be measured with an antibody, an antigen or a nucleic acid to which a polyacridinium compound is bound and which can be bound to the substance to be measured, (b) carrying out a luminescence treatment, and (c) measuring the luminescent intensity of the reaction solution.

Abstract: A method for quantitating accurately 1,5-anhydroglucitol, fructose or amylase in a sample that contains galactose using an enzymatic determination involves a pretreatment which removes galactose from the sample by an enzyme reaction in which galactose is a substrate.

Abstract: Glucose 6-phosphate dehydrogenase is stabilized in a clinical assay reagent with at least one stabilizer selected from among hydroxylamines, aldehyde scavengers dimethylthiocarbamoyl chloride, 2-(2-aminoethylamine) ethanol, and their salts. The reagent may be in liquid or lyophilized form.

Abstract: The present invention relates to a method for quantitative determination of NAD(P)H derived from a specific component, which comprises converting NAD(P)H present in a sample or formed from components other than the objective component by reactions into NAD(P) by the action of glutathione of oxidation type and glutathione reductase; decomposing the remaining glutathione of oxidation type by the action of .gamma.-glutamyl transpeptidase in the presence or in the absence of a mercapto compound; forming NAD(P)H from the component to be determined in the sample utilizing an NAD(P)H-forming reaction system; and quantitatively determining NAD(P)H.According to the method of the present invention, amylase activity, etc. in vital components containing maltose and glucose can be determined accurately.

Abstract: A method for determination of an analyte in a sample containing reducing substances is disclosed. After the decomposition of the reducing substances by reaction with hydrogen peroxide formed by enzymatic Redox reaction using a component in the sample which does not participate in another enzymatic Redox reaction using the analyte, the remaining hydrogen peroxide is decomposed, and then the analyte is subjected to enzymatic Redox reaction to form hydrogen peroxide which is then determined by a known method.

Abstract: A composition for testing periodontal diseases which diagnoses or prognosticates contraction or progress of the diseases or diagnoses the therapeutic value by promptly determining peptidase-like enzymatic activity in a specimen. The composition is a combination of a compound of the formula [1] or [2] or a mixture thereof, a chromogen and an oxidase:X-T-Pro-Y [1]orX'-Z'-Arg-Y' [2]wherein Pro is proline residue; Arg is arginine residue; X and X' are hydrogen or an amino protecting group, respectively; Y and Y' are a residue of a compound which can increase oxidation reaction rate of a chromogen with a oxidase in the presence of oxygen and is attached to the C-terminal of Pro or Arg, respectively; and T and Z' are an amino acid or peptide residue composed of 0 to 4 amino acids or their protected derivatives the C-terminal of which is attached to the N-terminal of Pro or Arg, respectively.

Abstract: The present invention provides a method for the determination of a compound having mercapto group which comprises reacting the compound with a chromogen represented by the following general formula (I): ##STR1## wherein Y is hydrogen or hydroxyl; R.sub.1, R.sub.2 and R.sub.3 may be the same or different, and are groups represented by the following general formula (II), (III) or (IV): ##STR2## wherein Z (which may be the same or different) is hydroxyl, amino, substituted amino, alkyl, substituted alkyl, alkenyl, aryl, substituted aryl, acyl, halogen, nitro, sulfo, carboxyl or alkoxy; n is 0, 1, 2, or 3; provided that at least one Z in R.sub.1, R.sub.2 and R.sub.3 is hydroxyl, amino, or substituted amino, in the presence of peroxidase or thiol oxide reductase, and determining the pigment thus formed.

Abstract: Disclosed is a method for the colorimetric determination of hydrogen peroxide in a sample by reacting a particular chromogen with the hydrogen perioxide in the presence of peroxidase and measuring the absorbancy of the reaction solution in the visible or near inflared ray region. Also disclosed is a test composition for carrying out the determination.

Abstract: Leucine aminopeptidase (LAP) activity or .gamma.-glutamyltranspeptidase (.gamma.-GTP) activity in a sample is determined by converting a substrate represented by the formula (I): ##STR1## wherein Z represents (CH.sub.3).sub.2 CHCH.sub.2 CH(NH.sub.2)--or (NH.sub.2)(COOH) CHCH.sub.2 CH.sub.2 --, R.sub.1 represents hydrogen, alkyl or substituted alkyl, R.sub.2 represents alkylene or hydroxyalkylene, R.sub.3 and R.sub.4 are the same or different and represents hydrogen, halogen, nitro, hydroxyl, sulfo, carboxyl, alkyl, and alkoxy, and salts thereof into a compound represented by the formula (II): ##STR2## wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 have the same meanings as defined above. The compound (II) is reacted with a chromogen to form a pigment or converted into a diazonium salt which is reacted with a coupling agent to form an azo dye. Absorption of a resultant colored reaction solution is measured.

Abstract: The present invention provides a method for the determination of NAD(P)H which comprises reacting a chromogen represented by the following general formula (I): ##STR1## wherein Y is hydrogen or hydroxyl; R.sub.1, R.sub.2 and R.sub.3 may be the same or different, and are groups represented by the following general formula (II), (III) or (IV): ##STR2## wherein Z is hydrogen, hydroxyl, amino, substituted amino, alkyl, substituted alkyl, alkenyl, aryl, substituted aryl, acyl, halogen, nitro, sulfo, carboxyl or alkoxy; n is 1, 2, or 3; provided that at least one Z in R.sub.1, R.sub.2 and R.sub.3 is hydroxyl, amino, or substituted amino; and Z.sub.s in Z.sub.n may be the same or different, with NAD(P)H in the presence of (1) peroxidase or thiol oxide reductase and (2) diaphorase or an electron carrier, and determining the pigment thus formed.

Abstract: A method and test composition for colorimetrically determining hydrogen peroxide in a sample includes a chromogen of the formula: ##STR1## which is reacted with hydrogen peroxide in the sample in the presence of peroxidase. The absorbancy of the reaction solution is then measured.