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Biomedical subjects
V P Chu
Publications and source records attributed to V P Chu.
Automated homogeneous immunoassay for gentamicin on the dimension clinical chemistry system.
BACKGROUND: Monitoring of the concentration of gentamicin in serum and plasma during therapy is widely recommended and practiced in hospitals. Our aim was to develop a homogeneous immunoassay based on particle-enhanced turbidimetric inhibition immunoassay technology to quantify gentamicin on the Dimension clinical chemistry system. METHODS: Assay performance was assessed on each of the Dimension models in a 15-instrument interlaboratory comparison study. A split-sample comparison (n = 1171) was also performed between the gentamicin methods on the Dimension system and the Abbott TDx analyzer, using multiple reagent and calibrator lots on multiple instruments. RESULTS: The Dimension method was linear to 25.1 micromol/L (12.0 microg/mL) with a detection limit of 0.63 micromol/L (0.3 microg/mL). Calibration was stable for 30 days. The within-run imprecision (CV) was <1.3%, and total imprecision ranged from 1.8% to 3.2% between 4.2 micromol/L (2.0 microg/mL) and 16.7 micromol/L (8.0 microg/mL) gentamicin. Linear regression analysis of the results on the Dimension method (DM) vs the Abbott TDx yielded the following equation: DM = 0.98TDx - 0.42; r = 0.987. Minimal interference was observed from structurally related compounds such as sagamicin, netilmicin, and sisomicin. CONCLUSION: The monoclonal antibody used in this method has similar reactivities toward the individual gentamicin subspecies C1, C1a, and C2, thus providing analytical recovery not significantly dependent on relative subspecies concentrations.
Anti-Bacterial Agents↗
Clinical evaluation of an EIA for the sensitive and specific detection of serum antibody to Trypanosoma cruzi (Chagas' disease).
A commercial EIA for the detection of antibody to Trypanosoma cruzi was clinically evaluated. The primary use of this test is in the diagnosis and screening of donated blood in Latin America. When compared with sera positive by xenodiagnosis, the assay had a clinical sensitivity of 100%. When tested against matched hemagglutination (HA) and immunofluorescence (IFA) results (i.e., when both tests gave negative results) the EIA had a specificity of 99.03% (305/308). The cross-reactivity of this test was determined using sera from malaria and leishmaniasis patients (obtained from Africa, ensuring that the sera did not contain Chagasic antibodies) and from schistosomiasis, toxoplasmosis, tuberculosis, syphilis, and systemic lupus erythematosus samples. The EIA was 100% specific whereas IFA or commercially available HA kits from Latin America cross-reacted with several of the samples. In this investigation, the EIA appeared to be at least as sensitive and more specific than IFA or HA in the serodiagnosis of Chagas' disease.
Animals↗
Absorption-enhanced solid-phase immunoassay method via water-swellable poly(acrylamide) microparticles.
Water-swellable hydrogel microspheres based on cross-linked polyacrylamide were used as solid supports in immunoassay formats. Capture antibody was covalently bound at the surfaces and the pore size of particles was such that these antibodies were excluded from the interiors. Upon contact with a solution containing immunological reactants, water molecules quickly penetrated the microspheres, causing them to swell, thereby concentrating analyte at the surface. Using swellable particles, the antigen capture rate during the first 5 min of incubation with antigen was two times that of antibody-coated 0.79 cm polystyrene beads. In addition, antibodies attached to lightly cross-linked swellable microparticles proved resistant to inactivation by ultrasonic energy, which can be used to accelerate immunological interactions.
Absorption↗
The immunochemistry of sandwich-ELISAs. IV. The antigen capture capacity of antibody covalently attached to bromoacetyl surface-functionalized polystyrene.
The antigen capture capacity of antibodies covalently immobilized on injection-molded polystyrene beads was evaluated. Bromoacetyl groups on the bead surfaces rendered them reactive to protein nucleophilic groups. The bromoacetyl surface exhibited up to a ten-fold greater capacity for protein compared to unmodified polystyrene, with no detectable dissociation such as occurs with simple adsorption. Biotinylated anti-fluorescein was immobilized on this surface both through direct covalent attachment and indirectly via streptavidin, which was first covalently attached to the bead. Comparisons of the resulting biological activity, normalized to the amount of anti-fluorescein on the bead, were made between the attachment methods and simple passive adsorption. The presence of the streptavidin spacer on the bromoacetyl surfaces improved the antigen capture capacity of antifluorescein, for fluoresyl-albumin by 45% compared to direct covalent linkage of the antibody to modified polystyrene and by 160% relative to antibody adsorbed on unmodified polystyrene.
Acetates↗
2,3-Diaminophenazine is the product from the horseradish peroxidase-catalyzed oxidation of o-phenylenediamine.
NMR and mass spectroscopic evidence has been obtained which indicates that the product of the oxidation of o-phenylenediamine by hydrogen peroxide, uncatalyzed or catalyzed by horseradish peroxidase, is 2,3-diaminophenazine. These results settle disparate literature descriptions. The process is most likely free radical in nature starting with the abstraction of a labile amino hydrogen atom.
Catalysis↗