Home About us Contact
|
Home About us Contact | ||
|
|
||
Competitive Enzyme-linked Immunosorbent (competitive + enzyme-linked_immunosorbent)
Selected AbstractsTargeted destruction of the polymerized human serum albumin binding site within the preS2 region of the HBV surface antigen while retaining full immunogenicity for this epitopeJOURNAL OF VIRAL HEPATITIS, Issue 1 2003J.-H. Park summary. The 55-amino acid (a.a.) preS2 region of the hepatitis B virus (HBV) envelope protein is highly immunogenic, and antibodies against this epitope confer seroprotection against HBV infections. Accordingly, various experimental and clinical studies for developing and evaluating HBV vaccines that include this particular epitope have been reported. However, a pitfall in using preS2 epitopes as part of a vaccinating antigen is that polymerized human serum albumin (pHSA), which is a normal constituent of the human serum, binds to and makes complexes with this particular region. Consequently, it is most likely that the antigen epitope is masked by serum pHSA and subsequently not detected by the immune system. To overcome these limitations, a novel single a.a substitute of the preS2 region was designed that corresponds to a tyrosine to serine exchange at position 140 of preS2. Competitive enzyme-linked immunosorbent assay showed that this substitution completely abolishes pHSA-binding activities in the mutated preS2 peptide, and CD spectra analysis revealed that this property might have been induced by slight conformational changes in its secondary structure. Nevertheless, the original B-cell epitope was still preserved in the mutated preS2 as determined by experimental immunization in mice. In this regard, the preS2(120,145/Y140S) sequence may be an HBV vaccine where epitopes, with intrinsic properties have been deleted without affecting the immunogenicity of the epitope itself. It is expected that the inclusion of this point mutated preS2 epitope will improve the efficacy of conventional preS2-containing HBV vaccines. [source] Fluorescence polarization immunoassay based on a monoclonal antibody for the detection of ochratoxin AINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 8 2004Won-Bo Shim Summary A fluorescence polarization immunoassay (FPIA) based on a monoclonal antibody for the determination of ochratoxin A (OTA) was developed. Fluorescein-labelled OTA derivative (tracer) was synthesized and purified by thin-layer chromatography. The optimized OTA FPIA had a dynamic range from 5 to 200 ng mL,1 with IC50 value of 30 ng mL,1 and a detection limit of 3 ng mL,1. The method developed was characterized by high specificity and reproducibility. Cross-reactivity with other mycotoxins (zearalenone, aflatoxins, patulin and T-2 toxin) was negligible (<0.1%). Methanol extracts of barley samples were used for the analysis. The results of OTA determination in barley were compared with those determined by indirect competitive enzyme-linked immunosorbent assay (ELISA). Recoveries for the samples spiked at 50, 100 and 500 ng g,1 levels were 91, 90 and 97%, respectively, for FPIA, and 98, 98 and 102%, for ELISA. Naturally contaminated barley samples were analysed by these methods but some disagreement was observed between the results. The FPIA method can be applied for screening of food samples for OTA residues without a complicated clean-up. [source] Competitive ELISA studies of neural thread protein in urine in Alzheimer's diseaseJOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 1 2007Susanna Levy Abstract A specific and reliable competitive affinity assay kit has been developed to quantitatively measure neural thread protein (NTP) in first morning urine samples. This assay, called the urine neural thread protein test (UNTP), is a competitive enzyme-linked immunosorbent assay (ELISA) format affinity assay using 32-well microtiter plates. The assay detects UNTP in the 10,60,µg/mL range (an improvement over earlier assays of 103 × ), is linear and more reproducible (average coefficient of variation [CV] 6.2% in precision studies). The utility of the assay has been demonstrated in urine samples from patients with Alzheimer's disease (AD) and controls (sensitivity of 90% and specificity of 91%). Test,retest assays of subjects with AD and controls were comparatively stable at intervals of 2 days to 4.5 years, which suggests that positive (elevated) or negative (normal) NTP levels do not fluctuate significantly over time with respect to the cutoff. J. Clin. Lab. Anal. 21:24,33, 2007. © 2007 Wiley-Liss, Inc. [source] Serotyping and genotyping of HIV-1 infection in residents of Khayelitsha, Cape Town, South AfricaJOURNAL OF MEDICAL VIROLOGY, Issue 12 2006G.B. Jacobs Abstract It is estimated that between 5.5 and 6.1 million people are infected with HIV/acquired immunodeficiency syndrome (AIDS) in South Africa, with subtype C responsible for the majority of these infections. The Khayelitsha suburb of Cape Town has one of the highest HIV prevalence rates in South Africa. Overcrowding combined with unemployment and crime in parts of the area perpetuates high-risk sexual behavior, which increases exposure to infection by HIV. Against this background, the objective of this study was to characterize HIV-1 in residents confirmed to be seropositive. Serotyping was performed through a competitive enzyme-linked immunosorbent assay (cPEIA). Genotyping methods included RNA isolation followed by RT-PCR and sequencing of the gag p24, env gp41 immunodominant region (IDR), and env gp120 V3 genome regions of HIV-1. With the exception of a possible C/D recombinant strain, all HIV-1 strains were characterized as HIV-1 group M subtype C. One individual was shown to harbor multiple strains of HIV-1 subtype C. In Southern Africa, the focus has been to develop a subtype C candidate vaccine, as this is the major subtype found in this geographical area. Therefore, the spread of HIV-1 and its recombinant strains needs to be monitored closely. J. Med. Virol. 78:1529,1536, 2006. © 2006 Wiley-Liss, Inc. [source] Preparation of anti-danofloxacin antibody and development of an indirect competitive enzyme-linked immunosorbent assay for detection of danofloxacin residue in chicken liverJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 7 2009Zhongqiu Liu Abstract BACKGROUND: Danofloxacin is used widely as both a clinical medicine for humans and a veterinary drug in animal husbandry. In this study a polyclonal anti-danofloxacin antibody was prepared for the first time and a simple and rapid indirect competitive enzyme-linked immunosorbent assay (cELISA) method based on the antibody was developed to monitor danofloxacin residue in chicken liver. RESULTS: The prepared antibody showed high sensitivity, with an IC50 value of 2.0 ng mL,1 towards danofloxacin, and good specificity, with significant cross-reactivity only towards pefloxacin (22%) and fleroxacin (21%) among commonly used (fluoro)quinolones evaluated in the study. The developed cELISA test kit had a detection limit of 0.8 ng mL,1, and satisfactory results were obtained when it was applied to chicken liver spiked with various levels of danofloxacin. The cELISA test kit was also used to detect danofloxacin in chicken liver samples purchased from a local food market, and the results were confirmed by liquid chromatography/mass spectrometry. CONCLUSION: The anti-danofloxacin antibody prepared in this study exhibits excellent quality, with high sensitivity and good specificity. The cELISA test kit based on the antibody has a very low detection limit and is suitable for use as an efficient screening method to detect danofloxacin residue in foods and food products. Copyright © 2009 Society of Chemical Industry [source] Urinary oxidative stress markers in young patients with type 1 diabetesPEDIATRICS INTERNATIONAL, Issue 1 2006IKUE HATA Abstract Background: Involvement of oxidative stress in the pathogenesis of diabetic vascular complications has been proposed. However, there are few methods to determine the status of oxidative stress both directly and quantitatively in young patients with type 1 diabetes. Methods: A total of 27 young patients with type 1 diabetes (mean age ± SD, 12.6 ± 4.2 years) with normal renal function and 38 healthy control subjects (13.0 ± 4.6 years) were investigated. Early morning voiding urine samples were collected. The concentrations of acrolein-lysine adducts, 8-hydroxy-2,-deoxyguanosine (8-OHdG) were determined using competitive enzyme-linked immunosorbent assay, and nitric oxide metabolites were measured using the colorimetric, non-enzymatic assay. Results: Urinary concentrations of 8-OHdG, but not acrolein-lysine adducts and nitric oxide metabolites, were significantly increased in the diabetic group. For diabetic patients, microalbuminuria was significantly correlated with higher concentrations of all three markers. Hemoglobin A1c values were significantly correlated with 8-OHdG values. Conclusions: These findings indicate that increased oxidative stress and the risk of vascular complications may be present at early stages of type 1 diabetes. [source] Evaluation of ELISA for imidacloprid detection in eastern hemlock (Tsuga canadensis) wood and needle tissuesPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 2 2009Brian M Eisenback Abstract BACKGROUND: Imidacloprid is the primary insecticide used against the exotic invasive insect hemlock woolly adelgid, Adelges tsugae Annand, a pest of eastern hemlock [Tsuga canadensis (L.) Carrière] trees in the eastern United States. A competitive enzyme-linked immunosorbent assay (ELISA) was evaluated for quantification of imidacloprid in eastern hemlock wood and needle tissues. RESULTS: Matrix effects in the form of false positives and overestimated imidacloprid concentrations were observed in both wood and needle extracts. Tissues required a 100,1000-fold dilution with water in order to reduce matrix effects. Standard curves in 1% wood or needle extract were not significantly different from standard curves prepared in water. Matrix effects were more pronounced at concentrations in the lower working range of the kit, with recovery of 5 µg L,1 imidacloprid more accurate than recovery of 0.2 µg L,1. CONCLUSION: ELISA remains a valuable tool for semi-quantitative imidacloprid detection within the hemlock system because of its sensitivity, cost and ease of use. However, a 1000-fold dilution of hemlock tissue extract is recommended to ensure accurate imidacloprid determinations. Copyright © 2008 Society of Chemical Industry [source] Quantification of cockroach allatostatin-like peptide and its myotropic effects in males of the earwig Euborellia annulipesPHYSIOLOGICAL ENTOMOLOGY, Issue 1 2001Roy Phitayakorn Summary A monoclonal antibody to allatostatin I of the cockroach Diploptera punctata was used to establish a competitive enzyme-linked immunosorbent assay for quantification of allatostatin-like peptides in the hindgut of the adult male earwig, Euborellia annulipes. Hindguts of 0-day males contained significantly more allatostatin-positive material than those of 8-day males fed on catfood. However, males starved for the first 8 days of adult life had significantly higher levels of allatostatin-positive material than those of either 0-day or of 8-day fed males. Hindguts from 0-day old males exhibited lower spontaneous motility in vitro than those from 8-day males. Hindguts from males at both ages responded to allostatin with reversible, dosage-dependent decreases in hindgut motility, and responded to proctolin with reversible, dosage-dependent increases in hindgut motility. When both allatostatin and proctolin were applied to hindgut preparations simultaneously and in equal concentrations, the response varied with the stage of the male. Starvation enhanced hindgut motility and abolished the response to allatostatin, but not to proctolin. These results indicate the presence of material similar to cockroach allatostatins in male earwigs, and that the levels change with age and physiological stage. Furthermore, such peptides may indeed be regulatory neuropeptides and could modulate hindgut contraction. There was an increase in sensitivity to exogenous allatostatin in the hindgut during development from day 0 to day 8 in feeding males, but a loss in sensitivity in response to starvation; sensitivity to exogenous proctolin also increased with age, but such responsiveness was not diminished by starvation. [source] Association of Serum Pentosidine With Arterial Stiffness in Hemodialysis PatientsARTIFICIAL ORGANS, Issue 3 2010YiLun Zhou Abstract Pentosidine is an advanced glycation end product (AGE). The present study was undertaken to investigate the association of serum pentosidine with carotid distensibility as a measure of arterial stiffness in hemodialysis patients. One hundred and three patients on maintenance hemodialysis were recruited. The distensibility coefficient of the common carotid artery was evaluated by an ultrasonic phase-locked echo-tracking system. Serum pentosidine was measured by competitive enzyme-linked immunosorbent assay. Serum albumin, lipid profile, calcium, phosphorus, intact parathyroid hormone (iPTH), high-sensitivity C-reactive protein (hs-CRP), and oxidized low-density lipoprotein (ox-LDL) levels were also measured. Correlation was determined by linear and multiple stepwise regression analysis. Serum pentosidine level studied in hemodialysis patients was 0.54 ± 0.13 µg/mL. No significant difference in serum pentosidine level was noted between patients with and without diabetes (0.59 ± 0.10 µg/mL vs. 0.53 ± 0.13 µg/mL, P = 0.062) as well as between patients with and without prior cardiovascular disease (CVD) history (0.56 ± 0.14 µg/mL vs. 0.53 ± 0.12 µg/mL, P = 0.206). In multivariate regression analysis, only age (, = 0.363, P < 0.001) and ox-LDL (, = 0.262, P = 0.004) were identified as independent determinants for serum pentosidine. Serum pentosidine was significantly correlated with carotid distensibility (r = ,0.387, P < 0.001), as well as age, ox-LDL, and hs-CRP. After adjustment for age, blood pressure, history of diabetes, prior CVD history, lipid profile, calcium, phosphorus, iPTH, hs-CRP, and ox-LDL, serum pentosidine was still negatively correlated with distensibility (, = ,0.175, P = 0.044). Serum pentosidine was independently associated with carotid distensibility in hemodialysis patients. This finding suggested that the accumulation of AGE might be an important pathway in the development of arterial stiffness in end-stage renal disease. [source] Highly frequent anti-idiotype antibody in cynomolgus monkeys developed against mouse-derived regions of anti-Fas antibody humanized by complementarity determining region graftingBRITISH JOURNAL OF PHARMACOLOGY, Issue 2 2009M Saito-Yabe Background and purpose:, We investigated the immunogenicity of a humanized anti-human Fas monoclonal antibody, R-125224, in cynomolgus monkeys to estimate its efficacy, as well as its toxicity in clinical situations. Experimental approach:, R-125224 was intravenously administered to cynomolgus monkeys at single doses of 0.4, 1.2, 6 and 30 mg·kg,1, and the plasma concentrations of R-125224 and anti-R-125224 antibody (ARA) were measured. We conducted a competitive enzyme-linked immunosorbent assay to determine which part of R-125224 was recognized by ARA. We also examined the retention of radioactivity in mononuclear cells and granulocytes after the injection of [125I]-R-125224 to a collagen-induced arthritis monkey model. Key results:, After i.v. administration of R-125224, the elimination of the plasma R-125224 concentrations was accelerated at around 10 days post-dose, and 10 of 12 monkeys were ARA positive. From an epitope analysis of ARA, the ARA produced in monkeys recognized the mouse-derived regions located in complementarity determining regions, but could not recognize the human IgG. After the injection of [125I]-R-125224 to a collagen-induced arthritis monkey model, a significantly longer retention of the radioactivity in mononuclear cells compared to granulocytes was observed. Conclusions and implications:, In monkeys, the development of antibodies against R-125224 is rapid and highly frequent. Our hypothesis is that this highly frequent development of ARA might be due to the binding of R-125224 to immune cells, and its circulation in monkey blood might contribute to an increase in its chances of being recognized as an immunogen. [source] | ||||||||||||||||