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Competitive Immunoassay (competitive + immunoassay)
Selected AbstractsCompetitive immunoassay by capillary electrophoresis with laser-induced fluorescence for the trace detection of chloramphenicol in animal-derived foodsELECTROPHORESIS, Issue 16 2008Can Zhang Abstract A competitive immunoassay using CE with an LIF detector was developed for the detection of chloramphenicol (CAP). The method was based on the competitive reactions between fluorescently labeled CAP hapten and free CAP, with a limited amount of anti-CAP antibody. The poly(N -isopropylacrylamide) (pNIPA) hydrogel was added in the separation buffer as a dynamic modifier to reduce adsorption and enhance reproducibility. The linear range and LOD for CAP were 0.008,5,,g/L and 0.0016,,g/L, respectively. An ELISA using the same immuno-reagents was also developed for the analysis of CAP, with an LOD of 0.03,,g/L. The sensitivity of this CE immunoassay (CEIA)-LIF was almost 20 times greater than that of the ELISA. Using CEIA-LIF, equilibrium was reached in 15,min and the analytical results were obtained within 5,min by CE separation. Sample preparation for CEIA-LIF was not time-consuming and the matrix effect was easy to remove. An LOD of 0.1,,g/kg CAP in food matrices was easily achieved. This method is thus proposed as a fast and sensitive means of detecting trace amounts of CAP residues in animal-derived foods. [source] Homogenous enzyme immunoassay for cyclosporine in whole blood using the EMIT®2000 cyclosporine specific assay with the COBAS MIRA-plus analyzerJOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 6 2001Shigeki Kimura Abstract We describe the evaluation of the EMIT®2000 cyclosporine specific assay kit, an enzyme-multiplied immunoassay for cyclosporine in whole blood, with a COBAS MIRA-plus analyzer. The enzyme used for the assay was glucose-6-phosphate dehydrogenase (EC 1.1.1.49 G6PDH) from Leuconostoc mesenteroides; the monoclonal antibody is fairly specific for cyclosporine, and is not reactive with most metabolites. The assay principle is based on competitive immunoassay with G6PDH-labeled cyclosporine and cyclosporine in sample to the anticyclosporine mouse monoclonal antibody binding site. The within-assay coefficient of variation (CV) of this method was 2.7,4.2% (n = 10) at the levels of 56.2,339.7 ,g/L. Day-to-day CVs ranged from 4.2,8.1% at the levels of 47.2,350.2 ,g/L. The within-day CVs ranged from 2.0,6.4% at the levels of 43.3,330.5 ,g/L. The functional detection limit was 24.9 ,g/L. Samples treated with pretreatment reagent were stable at least 5 hr. Calibration was stable at least 10 days. The analytical recovery was 81,109%. The correlation between values obtained with the EMIT®2000 cyclosporine specific assay kit (y) and fluorescence polarization immunoassay (FPIA) (TDxFLx) (x) was: y = 0.880x , 13.053 ,g/L (r = 0.984, Sy/x = 15.968, n = 71) with a mean difference of 31.42 ± 19.89 ,g/L ((TDxFLx , EMIT®2000) ± SD); for the FPIA (AxSYM) (x): y = 0.989 , 4.144 ,g/L (r = 0.981, Sy/x = 17.478, n = 71) with a mean difference of 5.56 ± 17.38 ,g/L ((AxSYM , EMIT®2000) ± SD); and for the radioimmunoassay (RIA, CYCLO-Trac SP) (x): y = 0.893 , 6.764 ,g/L (r = 0.993, Sy/x = 10.582, n = 71) with a mean difference of 22.18 ± 14.98 ,g/L ((RIA , EMIT®2000) ± SD) using the Bland-Altman technique. J. Clin. Lab. Anal. 15:319,323, 2001. © 2001 Wiley-Liss, Inc. [source] Development of an Antibody Hapten-Chip System for Detecting the Residues of Multiple Antibiotic Drugs,JOURNAL OF FORENSIC SCIENCES, Issue 4 2009Ailiang Chen M.Sc. Abstract:, The abuse of antibiotic drugs during animal production remains a worldwide problem and the subsequent detection of the residues of various drugs present at low concentrations in complex biological matrices poses significant analytical challenges. The present study outlines a practical biochip assay system to identify antibiotic residues in different animal tissue extracts. The system uses a simple but efficient multiresidue sample extraction procedure to isolate the antibiotic residues which were then identified directly using high-affinity monoclonal antibodies presented in a competitive immunoassay with conjugated antibiotic hapten-chips. The hapten-chip can analyze six samples each for eight antibiotics on a single chip within 3 h. The analytical results with both artificial positive standard samples and the incurred samples show that the antibody hapten-chip system has a comparable accuracy and a similar sensitivity to a standard ultra performance liquid chromatography,mass spectrometry (MS)/MS assay. In conclusion, an effective analytical screening system based on antibody hapten-chip was developed for detecting multiple antibiotic residues from multiple samples. [source] In vivo absorption of steroidal hormones from smart polymer based delivery systemsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 8 2010Sibao Chen Abstract The purpose of this study was to develop smart polymer based controlled delivery systems to deliver steroidal hormones after single subcutaneous (s.c.) injection at predetermined rates over extended period of time. In vivo absorption and pharmacokinetics of levonorgestrel (LNG) and testosterone (TSN) were investigated from the thermosensitive and phase sensitive polymeric controlled delivery systems. A selective, reliable, and rapid method for determination of serum LNG concentration was developed using high-performance liquid chromatography,tandom mass spectrometry with atmospheric pressure chemical ionization interface (HPLC,MS,MS with APCI), while TSN in serum samples was detected and quantified by a competitive immunoassay. The delivery systems controlled the absorption of LNG in rabbits up to 6 weeks from thermosensitive and ,4 weeks from phase sensitive polymeric delivery systems. In vivo study of TSN delivery systems in castrated rabbits controlled the release of TSN for at least 2 months from both thermosensitive and phase sensitive polymers. Thermosensitive and phase sensitive polymer formulations significantly (p,<,0.05) increased relative bioavailability of steroidal hormones compared to control. In conclusion, thermosensitive and phase sensitive polymer based delivery systems controlled the release in vivo in rabbits for longer duration after single s.c. injection. © 2010 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:3381,3388, 2010 [source] Immunolocalization of lingual antimicrobial peptide (LAP) in the bovine mammary glandANIMAL SCIENCE JOURNAL, Issue 4 2009Naoki ISOBE ABSTRACT Lingual antimicrobial peptide (LAP), a member of the ,-defensin family in cows, is involved in the innate immune system and plays a crucial role in killing a large variety of microorganisms. The aim of the present study was to demonstrate the immunolocalization of LAP in the mammary glands of cows. A LAP antibody was raised in a rabbit by immunity with a synthetic 11 amino acid sequence out of a 42-amino acid sequence of the mature form of LAP. The specificity of the LAP antibody was checked using a competitive immunoassay and Western blotting. Paraffin sections of the mammary gland were immunostained with LAP antibody. In the competitive immunoassay, an increase of synthetic LAP concentration suppressed the optical density. Western blotting analysis for LAP revealed the presence of the LAP peptide in mammary alveolar tissue. When the mammary gland was immunostained with LAP antibody, epithelial cells of both infected and non-infected alveoli were immunopositive. These results indicate that LAP is localized in the epithelium of non-infected as well as infected alveolus in the mammary gland in cows. [source] Influence of green and black tea on folic acid pharmacokinetics in healthy volunteers: potential risk of diminished folic acid bioavailabilityBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 6 2008N. Ceren Alemdaroglu Abstract Previous in vitro studies using Caco-2 cell monolayers suggested a possible interaction between green and black tea and folic acid at the level of intestinal absorption. The main purpose of the present study was to investigate a possible pharmacokinetic interaction between tea and folic acid in healthy volunteers. In an open-labeled randomized cross-over study, the pharmacokinetic interaction between tea and folic acid (0.4,mg and 5,mg) was investigated in healthy volunteers. Water was used as the reference drink. Subjects ingested 0.4,mg folic acid tablets with water, green or black tea (0.3,g extract/250,ml) or 5,mg folic acid tablets with water or green tea (0.3,g extract/250,ml). Blood samples were collected over a period of 8,h. Serum folate analysis was carried out by a competitive immunoassay which uses direct chemiluminescent technology. At the 0.4,mg folic acid dose, green and black tea reduced the mean Cmax of serum folate by 39.2% and 38.6%, and the mean AUC0 , , by 26.6% and 17.9%, respectively. At the 5,mg folic acid dose, the mean Cmax of serum folate was reduced by 27.4% and the mean AUC0 , , was decreased significantly by 39.9% by the co-application of green tea. The present results suggest an in vivo interaction between tea and folic acid with even low concentrations of green and black tea extracts yielding decreased bioavailabilities of folic acid. Copyright © 2008 John Wiley & Sons, Ltd. [source] High-Throughput Evaluation of Antioxidant and Pro-oxidant Activities of Polyphenols with Thymidine Protection AssaysCHEMBIOCHEM, Issue 7 2005Stéphane Meunier Dr. Abstract A recently reported high-throughput screening strategy has been applied to the rapid selection of new water-soluble antioxidants that display strong protective activities. Based on a competitive immunoassay, a triple-screening procedure was used to evaluate the ability of different compounds to protect thymidine under different oxidative stresses. The pro-oxidant effect of norbadione A in the presence of iron was observed, while some pulvinic acid derivatives proved strongly protective during , radiolysis, UV irradiation, and Fenton-like oxidation. [source] Competitive Enzymatic Fluorescence Immunoassay for Human IgG by Using a Temperature-Sensitive Phase Separating Polymer with Regulated Phase Transition TemperatureCHINESE JOURNAL OF CHEMISTRY, Issue 4 2008Peng LIN Abstract A new enzymatic fluorescence immunoassay for human IgG was developed using a temperature-sensitive polymer, poly(N -isopropylacrylamide-co-acrylamide) [P(NIP-AA)], as a carrier. The lower critical solution temperature of the P(NIP-AA) containing molar fraction of 8% for AA was 37 °C. In a competitive immunoassay, immobilized IgG and the standard IgG (or sample) competed for binding to a horseradish peroxidase labeled antibody at 33 °C in homogeneous format. After changing the temperature to separate the polymer-immune complex, the complex precipitate was re-dissolved and determined by coupling with the fluorescence reaction of hydrogen peroxide and p -hydroxyphenylacetic acid. The calibration graph for human IgG was linear over the range of 100,1000 ng/mL with a detection limit of 2.0 ng/mL. The method is rapid, sensitive and simple. The immune reaction efficiency was improved. In addition, the sensitivity of this method was close to that using traditional microtitration plates as carriers. However, the assay was much faster (the assay time decreased from 100,120 to 30 min). The method has been applied to the determination of the human IgG levels in human sera with satisfactory results. [source] Serum fasting cortisol in relation to bone, and the role of genetic variations in the glucocorticoid receptorCLINICAL ENDOCRINOLOGY, Issue 6 2007N. M. Van Schoor Summary Objective, To examine the relationship between endogenous cortisol and bone, and the role of genetic variations in the glucocorticoid receptor (GR). Design and patients, The Longitudinal Ageing Study Amsterdam (LASA), a population-based cohort study in older men and women. Measurements, Serum fasting cortisol was assessed by competitive immunoassay (n = 1214); bone mineral density (BMD) by dual X-ray absorptiometry (DXA) (n = 502); broadband ultrasound attenuation (BUA) by ultrasound (n = 1209); fractures by self-report (n = 1211); and GR gene polymorphisms (ER22/23EK, N363S, 9beta, BclI) were genotyped by Taqman (n = 858). Results, Higher serum fasting cortisol was significantly associated with lower BMD at all sites and BUA at the heel in women, although most relationships were attenuated by age and body mass index (BMI). The effect on femoral neck BMD remained statistically significant in the fully adjusted model (r = ,0·135, P = 0·04). No significant associations in men were found. Female 9beta G-allele carriers had 50·2 nmol/l lower cortisol and 1·2 lower free cortisol levels than AA homozygotes [P = 0·01 for (free) cortisol]. Furthermore, female BclI GG homozygotes had 54·8 nmol/l higher cortisol levels than C-carriers (P = 0·03). In the total population, BclI GG homozygotes had 0·05 g/cm2 lower trochanteric region BMD (P = 0·03). For the other GR gene polymorphisms, no significant associations were found. Conclusions, Higher cortisol levels are associated with lower femoral neck BMD in elderly women. The G allele of the 9beta polymorphism was associated with lower serum cortisol levels in women. Female BclI GG homozygotes had higher serum cortisol levels, and BclI GG homozygotes had lower trochanteric region BMD in the total population. [source] | ||||||||||||||||