Biomedical subjects

K Kubotsu

Publications and source records attributed to K Kubotsu.

4 recordsLinked to original sources

PubMed1995

Automated homogeneous liposome-based assay system for total complement activity.

We developed an automated homogeneous immunoassay, based on immune lysis of dinitrophenyl (DNP)-labeled liposomes, for measuring total complement activity. Liposome lysis caused by complement activity was detected spectrophotometrically from entrapped glucose-6-phosphate dehydrogenase activity. Complement activity in human sera was quantified by comparison with a calibration curve. For ease of application to fully automated routine clinical analyzers, we adopted a two-reagent system, one reagent containing a homogeneous population of small DNP-labeled liposomes and one containing antibody/substrate. This system required calibration only once a week. Within-run and between-run CVs were 0.4-1.3% (n = 10) and 1.8-4.7% (n = 10), respectively. Serum results were linear upon dilution (with saline) over a twofold range. Bilirubin, hemoglobin, Intrafat, and serum proteins such as rheumatoid factor, M protein, IgG, and IgA did not affect the assay results. The results (y) correlated well with those from a hemolytic complement activity test (x): y = 1.05x - 1.14, r = 0.92, on 66 samples in the range < 10- > 50 kU/L. This method should therefore be of great use for the determination of complement activity.

Adolescent↗

PubMed1992

Automated homogeneous liposome immunoassay systems for anticonvulsant drugs.

We developed automated homogeneous immunoassays, based on immunolysis of liposomes, for measuring phenytoin, phenobarbital, and carbamazepine from serum. Liposome lysis was detected spectrophotometrically from entrapped glucose-6-phosphate dehydrogenase activity. The procedure was fully automated on a routine automated clinical analyzer. Within-run, between-run, dilution, and recovery tests showed good accuracies and reproducibilities. Bilirubin, hemoglobin, triglycerides, and Intrafat did not affect assay results. The results obtained by liposome immunoassays for phenytoin, phenobarbital, and carbamazepine correlated well with those obtained by enzyme-multiplied immunoassay (Syva EMIT) kits (r = 0.995, 0.986, and 0.988, respectively) and fluorescence polarization immunoassay (Abbott TDx) kits (r = 0.990, 0.991, and 0.975, respectively). The proposed method should be useful for monitoring anticonvulsant drug concentrations in blood.

Anticonvulsants↗

PubMed1990

Colorimetric liposome lysis for assay of anti-streptolysin O antibody.

We developed an automated colorimetric assay based on liposome lysis for measurement of the titer of anti-streptolysin O antibodies (ASO) in human sera by using liposomes in which alkaline phosphatase (EC 3.1.3.1) was entrapped. The assay involved the inhibition by ASO of liposome lysis caused by streptolysin O. The procedure was fully automated for use with a routine clinical automated analyzer. The inter- and intra-assay precision showed that results were reproducible. Potential interfering substances such as bilirubin, hemoglobin, and triglycerides did not affect the results. With this assay, results correlated well with those by the Rantz-Randall method and the latex agglutination method (r = 0.900 and 0.890, respectively). This automated colorimetric assay for ASO should be of use for diagnosing streptococcal infections.

Alkaline Phosphatase↗

PubMed1990

Characterization of detergent dispersed cytidylate cyclase of rat brain.

Cytidylate cyclase was demonstrated to be distributed in various tissues of rat, with the highest activity in brain, and it was shown to be a membrane-bound type enzyme. The enzyme was effectively dispersed from the membrane fraction of rat brain with 0.3% (w/v) Triton X-100. The dispersed cytidylate cyclase had an optimal pH of 9.4 and the activity at a physiological pH of 7.5 was less than 20% of the maximum value. This enzyme completely lost its activity in the absence of divalent cation such as Mn2+ and Mg2+. The Km value for CTP was calculated as 0.0156 mM, by Lineweaver-Burk analysis. It was also found that activity of dispersed enzyme was inhibited by ATP, but not GTP. Both forskolin and lanthanum chloride, which affect adenylate cyclase, showed no effect on cytidylate cyclase. These results indicate that cytidylate cyclase is a unique membrane-bound enzyme distinct from purine nucleotide cyclases, adenylate cyclase and guanylate cyclase.

Adenosine Triphosphate↗