A.A.G. Candlish

University of Strathclyde, Glasgow, Scotland, United Kingdom

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Publications (11)24.22 Total impact

  • D.K. Oladepo, A.A.G. Candlish, W.H. Stimson
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    ABSTRACT: Polyclonal antibody sensitive to Listeria was assayed for the detection of Listeria using two different methods, direct and sandwich enzyme linked immunosorbent assays (ELISAs). The direct ELISA uses anti-goat IgG antibody conjugated with horse-radish peroxidase, while the sandwich ELISA uses two antibodies both specific to Listeria antigens, one coated onto the microtitre plate and the other conjugated to horse-radish peroxidase. The results obtained show that the direct ELISA is superior to the sandwich ELISA in two distinct ways: (i) with direct ELISA the non-Listeria gave readings <0.2, whereas with sandwich ELISA it gave readings of 0.3–0.4; (ii) the direct ELISA is more cost-effective than the sandwich ELISA.
    Letters in Applied Microbiology 06/2008; 14(2):26 - 29. DOI:10.1111/j.1472-765X.1992.tb00639.x · 1.63 Impact Factor
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    ABSTRACT: Aflatoxins B1, B2, G1 and G2 can be easily and rapidly detected in aqueous solutions using an affinity chromatography column coupled to a monoclonal antibody specific for the toxin molecules. Water: methanol extracts of food uncontaminated with aflatoxins were spiked with aflatoxins, diluted with water, and passed through the affinity matrix. The monoclonal antibody is bound to the aflatoxin, which can then be released by using a small volume of methanol. This results in both concentration and separation of the aflatoxin present in solution. As little as 5 ng of aflatoxin can be visualized in the methanol eluate if passed over a small florisil tip under ultraviolet light, while 0.5 ng can be detected in the methanol eluate if analysed by high performance liquid chromatography (HPLC). Thus, this system can be used to test for aflatoxins in contaminated samples by spot testing (> 5 ng) or as a means of HPLC clean-up for quantitative analysis at subnanogram levels. The advantages of this immunological assay in relation to other immunoassays and traditional methods are discussed.
    International Journal of Food Science & Technology 06/2007; 23(5):479 - 485. DOI:10.1111/j.1365-2621.1988.tb00604.x · 1.35 Impact Factor
  • J Lacey, N Ramakrishna, A A Candlish, J E Smith
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    ABSTRACT: Immunoassays provide rapid, specific, sensitive and inexpensive methods for analysing mycotoxins but have generally been tested individually. Mycotoxigenic fungi rarely occur in pure culture in nature, and different mycotoxins may occur together. It would therefore be advantageous if several immunoassays for different mycotoxins could utilize a single extract. Monoclonal antibodies specific for ochratoxin A, aflatoxin B1 and T-2 toxin, raised at the University of Strathclyde, allow detection limits of 1 ng/ml ochratoxin A, 0.1 ng/ml aflatoxin B1 and 10 ng/ml T-2 toxin, when used in competitive enzyme-linked immunosorbent assays. These antibodies have been used to assay ochratoxin A. aflatoxin B1 and T-2 toxin in a single acetonitrile: 0.5% KCl:6% H2SO4 (89:10:1) extract of cereal grain. Extracts were either diluted 1:10 for direct assay or subjected, before assay, to a simple liquid-liquid clean-up procedure, which removed interfering substances and resulted in a 5:1 concentration. Recoveries from barley to which mycotoxins had been added averaged 95.8% for ochratoxin A, 93.8% for aflatoxin B1 and 80.6% for T-2 toxin, and the detection limits were 5 ng/g for ochratoxin A, 4 ng/g for aflatoxin B1 and 50 ng/g for T-2 toxin. Mean coefficients of variation within and between assays and between subsamples were less than 12% for ochratoxin A and aflatoxin B1 but up to 17% for T-2 toxin in assays of barley inoculated with toxigenic fungi.(ABSTRACT TRUNCATED AT 250 WORDS)
    IARC scientific publications 02/1991;
  • A. A. G. Candlish, J E Smith, W H Stimson
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    ABSTRACT: A monoclonal antibody (mAb) has been produced to aflatoxin B1 (AF B1) after successful immunization of mice and fusion of sensitized spleen cells with myeloma cancer cells. The mice were immunized with AF B1-oxime-protein conjugate. Positive mAbs were screened using an indirect ELISA specific for AF B1. The selected mAb was then developed in direct competitive ELISA and immunoaffinity column chromatography methods for aflatoxin detection in foods and feeds. Both assays are rapid, sensitive, specific and require only the minimum of sample preparation. Both immunological assays have now been commercialized and are produced in convenient ready-made kit formats.
    Letters in Applied Microbiology 05/1990; 10(4):167-9. DOI:10.1111/j.1472-765X.1990.tb00106.x · 1.75 Impact Factor
  • A.A.G. Candlish, J E Smith, W H Stimson
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    ABSTRACT: Specific monoclonal antibodies (MABs) against aflatoxins, ochratoxin A, zearalenone, diacetoxyscirpenol and T-2 toxin have been prepared in various laboratories by the application of hybridoma technology to mycotoxins. These antibodies can be selected for sensitivity, reduced cross-reactivity, reliability and ease of production. When a suitable antibody is chosen it can then be used in a rapid immunological method such as an enzyme-linked or radio-immunoassay or immunoaffinity chromatography system. These assays have a lower limit of mycotoxin detection in the ng/ml range and have been applied to the determination of mycotoxins in samples such as maize, peanuts, peanut butter, milk and porcine kidneys. Using these immunoassay techniques, sample preparation has generally been simplified to a matter of solvent extraction of mycotoxins from the sample followed by dilution; under these conditions, levels of 1-5ug of mycotoxins/kg of sample can be found. The application and advantages of MABs to mycotoxins and the use of these antibodies in various assay techniques is discussed.
    Biotechnology Advances 02/1989; 7(3):401-18. DOI:10.1016/0734-9750(89)90182-1 · 8.91 Impact Factor
  • A A Candlish, W H Stimson, J E Smith
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    ABSTRACT: A simple and rapid indirect enzyme-linked immunosorbent assay was developed for the quantitative determination of ochratoxin A in barley after the successful production of a high affinity, specific monoclonal antibody. A rapid sample cleanup was achieved by extracting ochratoxin A from barley with chloroform and partitioning the toxin into bicarbonate buffer; the buffer solution was then added directly to the assay plate and ochratoxin A content was assessed. Recoveries were greater than 85% and detection limits were 5 micrograms ochratoxin A/kg barley.
    Journal - Association of Official Analytical Chemists 01/1988; 71(5):961-4.
  • A.A.G. Candlish, W.H. Stimson, J.E. Smith
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    ABSTRACT: A simple procedure was validated for the routine immunochemical analysis of AFB1 in peanut kernels, peanut butter and maize. The specificity, affinity and sensitivity of the monoclonal antibody (McAb) employed was such that minimal sample preparation was required. The enzyme immunoassay (EIA) had a sensitivity for standard AFB1 of 0·2 ng ml−1 with a working range up to 30 ng ml−1 and was not significantly affected by matrix interference of samples. Essential protocol features were (1) blending substrate with methanol: water; (2) filtering blended sample; and (3) analysis of filtrate by EIA after dilution with buffer. Average recoveries of AFB1 spiked samples at levels of 6–400 ppb were 90–112·5%. Using laboratory prepared samples contaminated with Aspergillus flavus there was high positive correlation (r = 0·97) when EIA results were compared with thin layer chromatography (TLC) techniques.
    Food Microbiology 04/1987; DOI:10.1016/0740-0020(87)90030-X · 3.37 Impact Factor
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    ABSTRACT: By using an indirect enzyme-linked immunosorbent assay, eight monoclonal antibodies (MAbs) were selected. Mice were immunized with ochratoxin A that was conjugated to bovine serum albumin. The hybridoma cell line designated 10G2 was grown in tissue culture and as an ascites tumor. The MAb was characterized to be specific to ochratoxin A and of the immunoglobulin G (IgG) class. Subsequently, the ascites fluid of this hybridoma was used in a competitive solid-phase IgG radioimmunoassay on protein A-Sepharose CL-4B, with [14C]ochratoxin A as tracer. Porcine kidneys were extracted with 0.5% phosphoric acid in chloroform. A two-step cleanup was achieved on a Sep-Pak C18 cartridge and a Sep-Pak silica cartridge. Radioimmunoassay with MAbs coupled to protein A-Sepharose CL-4B allowed the detection of ochratoxin A in porcine kidneys at a concentration as low as 0.2 ng/g.
    Applied and Environmental Microbiology 04/1987; 53(3):514-8. · 3.95 Impact Factor
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    ABSTRACT: A monoclonal antibody (McAb) specific for ochratoxin A (OA) has been developed. The McAb has low cross-reactivity for ochratoxin α, although cross-reactivity with the synthetic ochratoxin C was high. The affinity dissociation constant of the McAb was found to be 6-2 × 107 M-1 by ELISA. A competitive enzyme immunoassay was developed with this McAb having a sensitivity of 10 μg/ml and a working range up to 10 μ/ml of OA in standard solutions.
    Letters in Applied Microbiology 12/1985; 3(1):9 - 11. DOI:10.1111/j.1472-765X.1986.tb01535.x · 1.63 Impact Factor
  • A. A.G. Candlish, W. H. Stimson, J. E. Smith
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    ABSTRACT: A monoclonal antibody (McAb) was produced after fusion of mouse (X63.Ag8.6.5.3) myeloma cells with spleen cells isolated from female Balb-c/NZB F1 hybrid mice immunized with aflatoxin B1 (oxine)-keyhole limpet haemocyanin conjugate. The hybridoma cell line producing antibody specific for aflatoxin B1 (AFB1) was grown in tissue culture and as an ascites tumour. The ascitic fluid gave suitably high dilution titres (1:800 000) by enzyme immunoassay and was conjugated to horseradish peroxidase by a two-step procedure with glutaraldehyde. The conjugate was used to develop a direct competitive enzyme-linked immunosorbent (ELISA) assay for AFB1. The sensitivity of the ELISA was 0–2 ng/ml with a working range up to 10 ng/ml for AFB1. The specificity of the McAb was determined and it was shown not to cross-react significantly with any of the metabolites tested. This McAb and the direct competitive ELISA described may prove of use in the detection of AFB1 in foods and feeds.
    Letters in Applied Microbiology 02/1985; 1(3):57 - 61. DOI:10.1111/j.1472-765X.1985.tb01489.x · 1.63 Impact Factor
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    ABSTRACT: Aflatoxin B1 (B1), T-2 toxin (T2), and ochratoxin A (OA) were assayed in a single extract from barley grain by using competitive enzyme linked immunosorbent assays (ELISAs) with monoclonal antibodies. B1 and T2 monoclonal antibodies were conjugated to horseradish peroxidase for direct competitive ELISA while an indirect competitive ELISA was used for OA determination. The competitive ELISA detected 0.1 ng/mL of B1, 10 ng/mL of T2, or 1 ng/mL of OA. Acetonitrile-0.5% KCl-6% H2SO4 (89 + 10 + 1) extracts of barley grain either were diluted 1:10 for direct assay or were subjected to a simple liquid-liquid cleanup procedure to concentrate the extract 10:1 before assay. For cleanup, water was added to the acetonitrile extract to partition water-soluble interfering substances, and then the mycotoxins were re-extracted with chloroform. The chloroform extract was evaporated to dryness and redissolved in Tris HCl buffer for ELISA. The mean recoveries from barley spiked with 4-60 ng/g of B1, 50-5000 ng/g of T2, and 5-500 ng/g of OA were, respectively, 93.8, 80.6, and 95.8%. The mean within-assay, inter-assay, and subsample coefficients of variation by ELISA of barley grain colonized with toxigenic fungi were less than 12% for B1 and OA but as high as 17% for T2.
    Journal - Association of Official Analytical Chemists 73(1):71-6.