Enzyme linked immunosorbent assay (ELISA) for the determination of protein-A

1986 ◽  
Vol 6 (11) ◽  
pp. 933-936 ◽  
Author(s):  
P. J. Considine ◽  
P. Duggan ◽  
A. Eadie
Keyword(s):  
Immunosorbent Assay ◽  
Protein A ◽  
Competitive Elisa ◽  
Routine Screening ◽  
Enzyme Linked Immunosorbent Assay ◽  
Culture Supernatants

A competitive ELISA for the determination of protein-A concentration in culture supernatants is described. The sensitivity of the assay is 50 ng/ml and it may be used to determine concentrations of protein-A up to 1000 ng/ml. The assay is specific, rapid and suitable for routine screening of protein-A producing microorganisms.

Application of ELISA to Retail Survey of Aflatoxin B1 in Peanut Butter

1986 ◽  
Vol 49 (10) ◽  
pp. 792-795 ◽  
Author(s):  
BHANU P. RAM ◽  
L. PATRICK HART ◽  
RICHARD J. COLE ◽  
JAMES J. PESTKA
Keyword(s):  
Immunosorbent Assay ◽  
Aflatoxin B1 ◽  
Coefficient Of Variation ◽  
Simple Procedure ◽  
Peanut Butter ◽  
Competitive Elisa ◽  
Routine Screening ◽  
Enzyme Linked Immunosorbent Assay

A simple procedure was devised for the routine screening of aflatoxin B1 (AFB1) in peanut butter using enzyme-linked immunosorbent assay (ELISA). Peanut butter samples (5 g) were artificially contaminated with AFB1 and extracted by blending with 25 ml of 55% methanol and 10 ml of hexane. The extract was filtered and aqueous filtrate analyzed by a direct competitive ELISA. Recovery of AFB1 added to peanut butter samples ranged from 85 to 112%, with an average inter-well coefficient of variation of 18.4%. The inter-assay coefficient of variation was 22.7%. Using this procedure, only 3 of 63 commercial samples of peanut butter had detectable levels (>5.0 μg/kg) of AFB1.

scholarly journals Determination of Azadirachtin in Agricultural Matrixes and Commercial Formulations by Enzyme-Linked Immunosorbent Assay

2001 ◽  
Vol 84 (4) ◽  
pp. 1001-1010 ◽  
Author(s):  
Kalidindi Hemalatha ◽  
Namburi B K Venugopal ◽  
Namburi B K Venugopal ◽  
Beedu S Rao
Keyword(s):  
Immunosorbent Assay ◽  
Cross Reactivity ◽  
Competitive Elisa ◽  
Enzyme Linked Immunosorbent Assay ◽  
Agricultural Commodities ◽  
Indirect Competitive Elisa ◽  
Capture Assay ◽  
Ic50 Value ◽  
Antibody Capture

Abstract An enzyme-linked immunosorbent assay (ELISA) was developed for azadirachtin (aza), a biopesticide from the neem tree (Azadirachta indica A. Juss). The immunogen was synthesized by epoxidation using the furan ring in the aza molecule. Rabbits were immunized with either bovine serum albumin (BSA)-azadirachtin or ovalbumin (OA)-azadirachtin conjugate. Evaluation of the antisera by antibody capture assay showed that the antibody titer of antisera raised against OA-aza was 1:30 000. An indirect competitive ELISA was developed with BSA-azadirachtin as coating antigen and aza-specific antibodies raised against OA-aza immunogen. The immunoassay showed an inhibitory concentration (IC50) value of 75 ppb, with a range of detection from 0.5 to 1000 ppb for azadirachtin [based on regression analysis, y = 85.87 (−18.89x); r2 = −0.97]. Cross-reactivity of the antibodies with 2 aza- derivatives (22,23-dihydro-23β-methoxy azadirachtin and 3-tigloylazadirachtol) was 33 and 29%, respectively. The indirect competitive ELISA was validated and evaluated by quantitating aza in spiked agricultural commodities and from neem formulations. Azadirachtin was spiked into 5 different agricultural commodities: tomato, brinjal, coffee, tea, and cotton seed at 500 and 1000 ppb and recovered at 62–100%. In samples drawn from 6 lots, the aza content in neem-seed kernels ranged from 0.1 to 0.15%; in commercial neem formulations the content ranged from 200 to 2000 ppm. The method developed may be applied to environmental monitoring of aza and quality assurance studies of aza-based commercial formulations.

scholarly journals Simple assay for staphylococcal enterotoxins A, B, and C: modification of enzyme-linked immunosorbent assay

1978 ◽  
Vol 8 (5) ◽  
pp. 473-479
Author(s):  
G Stiffler-Rosenberg ◽  
H Fey
Keyword(s):  
Immunosorbent Assay ◽  
Competitive Elisa ◽  
Enzyme Linked Immunosorbent Assay ◽  
Sensitive Test ◽  
Single Tube ◽  
Cross Reactions ◽  
Food Extract ◽  
Staphylococcal Enterotoxins ◽  
Culture Supernatants

The enzyme-linked immunosorbent assay (ELISA) introduced for the detection of staphylococcal enterotoxins by Saunders et al., Simon and Terplan, and ourselves has proved to be a simple, reliable, and sensitive test. A new modification is described that uses polystyrene balls (diameter, 6 mm) coated individually with antibody against one of the toxins A, B, or C. In a single tube, 20 ml of the food extract was incubated with the three balls differently stained, which were then each tested for the uptake of enterotoxin by a competitive ELISA. A concentration of 0.1 ng or less of enterotoxin per ml can be measured, making tedious concentration procedures of the extracts superfluous. Culture supernatants and extracts from foods artificially or naturally contaminated with toxin were successfully examined. Cross-reactions did not occur, and nonspecific interfering substances did not create serious problems.

SENSITIVE AND SPECIFIC ENZYME-LINKED IMMUNOSORBENT ASSAY FOR UROKINASE-TYPE PLASMINOGEN ACTIVATOR IN HUMAN PLASMA

1987 ◽  
Author(s):  
J Grøndahl-HANSEN ◽  
N Agerlin ◽  
L S Nielsen ◽  
K Danø
Keyword(s):  
Plasminogen Activator ◽  
Immunosorbent Assay ◽  
Enzyme Linked Immunosorbent Assay ◽  
Mean Values ◽  
Amino Terminal ◽  
Type Plasminogen Activator ◽  
Healthy Donors ◽  
Urokinase Type Plasminogen Activator ◽  
The Mean

An enzyme-linked immunosorbent assay (ELISA) was developed for the measurement of human urokinase-type plasminogen activator (u-PA) in plasma and serum. Microtiter plates were coated with a monoclonal antibody and incubated with standard or sample. Bound u-PA was quantitated with polyclonal antibodies conjugated with biotin, followed by avidin-peroxidase. The assay was 10-fold as sensitive as other previously reported ELISAs, the detection limit being approximately 1 pg of u-PA in a volume of 100 μl with a linear dose-response up to 15 pg of u-PA. The assay detected active u-PA and its inactive proenzyme form equally well and the recovery of both forms was higher than 90% in plasma. A variety of structurally related proteins, including t-PA, were tested, but no reaction with proteins other than u-PA and its amino-terminal degradation product were observed. The intra-assay and inter-assay coefficients of variation for determination of u-PA in plasma were 7.6% and 8.4%, respectively. The assay was equally applicable to serum. The values obtained with plasma and serum were similar, and the results were not affected by small variations in the preparation of the samples. The ELISA was used to measure the concentration of u-PA in plasma from 34 healthy donors. The mean values for u-PA in plasma from healthy donors was 1.1 ng/ml ± 0.3 ng/ml (SD) (range 0.6 - 1.5 ng/ml). No significant differences were found between men and women and no correlation between u-PA concentration and age could be demonstrated.The mean u-PA concentration in plasma from healthy donors obtained in this study is substantially lower than that reported by others. This might be due to different methods of determination of the protein content of the standard preparations or to differences in the specificity of the assays.

Determination of plasma pantothenic acid by indirect enzyme linked immunosorbent assay

1990 ◽  
Vol 10 (4) ◽  
pp. 439-448 ◽  
Author(s):  
Won O. Song ◽  
Allen Smith ◽  
Carl Wittwer ◽  
Bonita Wyse ◽  
Gaurth Hansen
Keyword(s):  
Immunosorbent Assay ◽  
Pantothenic Acid ◽  
Enzyme Linked Immunosorbent Assay
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