摘要:

Mycotoxin research throughout the world focuses primarily on the problems associated with stored grains, legumes and the commodities produced from these feed stocks. While contaminated grains and legumes represent a direct threat of major importance to both human and animal consumers, they are not the only source of mycotoxins important to the agricultural sector. Grazing animals are exposed to mycotoxins produced by fungi resident in the pastures they graze, thus, in pastoral agricultural systems, a different spectrum of mycotoxicoses takes prominence. The analysis of toxins from herbage samples by conventional means (such as liquid chromatography and high‐pressure liquid chromatography) is often difficult, slow and expensive. Consequently, we have developed immunoassays which permit analysis of simple extracts and allow the rapid quantification of mycotoxins in large numbers of herbage samples. We detail enzyme‐linked immunosorbent assays using both polyclonal and monoclonal antibodies for the measurement of Fusarium toxins (zearalenone and the trichothecenes), sporidesmin, and the indole‐, diterpenoid and ergot alkaloids of endophytic fungi. Other applications using immunoanalytical techniques are also detailed.

ISSN:0954-0105    

DOI:10.1080/09540109409354821

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Multi‐analyte screening methods for β‐agonists in faeces and feeds based on enzyme immunoassay (EIA) were developed. Commercially available EIA kits were used, and the results presented. The extraction for both matrices was performed under acid conditions. The addition of an organic solvent to the extradant, resulting in higher recoveries, was only retained for feeds as the background absorption for faeces increased substantially. Clean‐up for faecal extracts was achieved in a one‐step extraction with isobutyl alcohol. Detection limits in faeces were slightly different for the two types of kits used. They ranged from 0.8ng g−1for clenbuterol to 10ng g−1for terbutaline. In feeds, corresponding detection limits for both compounds were 5 ng g−1and 110 ng g−1. Confirmation of EIA positives was established by liquid chromatography with post‐column diazotation and gas chromatography‐mass spectrometry. In the screening of faeces over 1 year about 70% of the EIA positive samples were confirmed as positive.

ISSN:0954-0105    

DOI:10.1080/09540109409354822

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A screening method was developed providing reliable detection of three chemically different β‐agonist model compounds, clenbuterol (50 ppb), salbutamol (500 ppb) and terbutaline (500 ppb). The method comprised an extraction with a mixture of acidic KH2PO4buffer plus methanol followed by detection by enzyme immunoassay using an antibody raised against clenbuterol‐diazo‐bovine serum albumin. The background signals of 107 feed samples of different composition were measured, and 86% were ≤ 2.45 ng clenbuterol equivalents g‐1. The highest values were 9–56 and 8–98 ng clenbuterol equivalents g‐1, found in two samples of mineral supplements. Analysis of spiked samples showed mean recoveries of 106 (clenbuterol) to 110% (salbutamol) and coefficients of variation of 13–22% over the different materials. Selected groups of feed materials, such as soybean meal (n =8), milk replacer (n =15), dairy concentrate (n =12), feed for poultry (n =5), protein concentrate (n =3) and ground grain meals (n =5) provided blanks all ≤ 2.58 ng clenbuterol equivalents g−1and recoveries between 97 and 124%; the coefficients of variation ranged from 4 to 14%. Although mineral supplements gave slightly less reliable results using this method with varying recoveries (22–189%) a clear differentiation of positives and negatives was always possible at the levels of interest. It may be possible to detect other β‐agonists that show cross‐reactivity with the antibody used for the immunoassay.

ISSN:0954-0105    

DOI:10.1080/09540109409354823

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Clenbuterol residue analysis of liver, kidney and muscle samples was performed using immunoaffinity chromatography for sample clean‐up and an enzyme‐linked immunosorbent assay (ELISA) as the means of measurement. The method was developed to enable rapid, specific, sensitive, reliable and cost‐effective detection of clenbuterol residues in tissue samples. After comprehensive validation, the method was employed routinely in testing 1005 tissue samples from which performance data have been collated. Positive samples from the ELISA method were confirmed by gas chromatography‐mass spectrometry.

ISSN:0954-0105    

DOI:10.1080/09540109409354824

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Commercially available maleic anhydride‐activated enzyme‐linked immunosorbent assay (ELISA) plates were used to immobilize atrazine in the form of aminohexyl‐atrazine (AHA). The immobilized atrazine was used to create a competitive s‐triazine assay. The assay based on the pre‐activated ELISA plates was compared with previously used assays where the binding of atrazine to the plate was indirect through an AHA‐dextran conjugate. Atrazine, in the form of AHA, bound quickly and reliably to the activated ELISA wells, and a competitive immunoassay was established with similar effectiveness to an assay based on a carrier conjugate. The ELISA format in general has many advantages to the end user, including the need for only small sample volumes, rapid assays and ease of automation. The availability of ELISA plates which spontaneously immobilize small amine‐containing ligands such as AHA might open up new possibilities for assay development. Moreover, it allows the presentation of small antigens without a carrier protein.

ISSN:0954-0105    

DOI:10.1080/09540109409354825

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Different immunization procedures were tested to find methods to enhance the proportion of monoclonal antibodies reacting equally well with native and denatured proteins for use in food analysis. Antibodies to soybean trypsin inhibitor with the desired characteristics were obtained by immunization with the denatured protein. Antibodies to ovomucoid were obtained by long‐term immunization. The monoclonal antibodies to ovomucoid were of the IgM class.

ISSN:0954-0105    

DOI:10.1080/09540109409354826

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Discrepancies between food content and label can lead to adverse reactions in people with hypersensitivity to particular food components. Over a 3‐year period, 20 occasions arose in Sweden where discrepancies between label and content were confirmed. In 14 cases the investigation was initiated because of adverse reactions observed by individuals with known disease. Analysis of the offending food included qualitative and quantitative antibody‐based techniques. The unexpected food ingredients were hazelnut, peanut, egg, milk, wheat, soy and chicken protein. The offending foods were chocolate, ice cream, meringue, lollypop, meatballs, sausage, hamburger, ham, kebabs, buns, pasta and buckwheat flour. Our study showed that simple immunological methods can be used for analysis of food protein for verification of contamination or mislabelling.

ISSN:0954-0105    

DOI:10.1080/09540109409354827

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The mixing and baking properties of wheaten doughs are determined largely by the content, composition and interactions of the major groups of flour proteins, the disulphide‐bonded glutenin subunits and monomeric gliadins. Prediction of dough and bread quality is currently based on medium‐scale rheological and baking tests, but the slow throughput of such tests limits their use both by millers and baking companies and in early‐generation screening by plant breeders. Thus identification and quantification of specific flour proteins by immunoassay has the potential advantages of speed, simplicity and applicability to small samples in breeding. Technical problems can arise from the low solubilities of these proteins and their high degrees of sequence homology (which often give rise to extensive antibody cross‐reaction). These problems can be minimized by modifications to methods and combining monoclonal antibodies with selected extraction conditions to enhance the functional specificity of the assay. Limitations also arise from attempting to predict the behaviour of a complex system, in which molecular interactions and processing changes have been important, purely from flour polypeptide composition. We have used quantitative immunoassays for specific groups of glutenins and gliadins to predict aspects of dough strength and extensibility, while ‘yes‐no’ direct enzyme‐linked immunosorbent assays can be used to screen for products of particular wheat or translocated rye genes associated with specific dough qualities. Monoclonal antibodies are also being employed to purify specific flour proteins under non‐denaturing conditions and in conjunction with novel very small scale dough testing equipment to directly assess functionality in doughs.

ISSN:0954-0105    

DOI:10.1080/09540109409354828

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Allergenicity to Brazil nut protein fractions and to a purified methionine‐rich 2S protein, considered to be similar to the allergens of other oilseeds, has been followed through IgG1and IgE synthesis after mouse subcutaneous immunization. The allergenic capacities of all protein fractions and of the 2S protein are not as prominent. Oral intake of Brazil nuts in several doses was also tested in mice and rats as a possible route of immunization, but instead of immunization, a systemic tolerance was induced. This state of immunological tolerance was more efficiently induced by a scheme of multiple feeding than by a single feeding.

ISSN:0954-0105    

DOI:10.1080/09540109409354829

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

An extract of dry‐roasted commercial peanut mix (CPE) was examined for allergenic activity in peanut‐sensitive individuals, using skin tests and radioallergosorbent (RAST) assays. Proteins in the extract were characterized by sodium dodecyl sulfate polyacry‐lamide gel electrophoresis (SDS‐PAGE) and immunoblotting. The proteins were electro‐eluted in three fractions in the ranges 15–25, 26–58 and 65 kDa. The 15–25 kDa molecular weight fraction produced the most reactive skin tests in peanut‐sensitive subjects and was chosen for monoclonal antibody production. Six hybridoma cell lines secreting peanut‐specific antibodies of the IgM isotype (kappa light chain) were produced. Immunopurified CPE proteins were then subjected to SDS‐PAGE, resulting in five major bands with approximate molecular weights of 14, 25, 38, 40 and 44 kDa. Immunoblotting of these separated proteins revealed: (1) three bands with approximate molecular weights of 38, 44 and 65 kDa, which bound IgE from peanut‐sensitive patients; and (2) that the monoclonal antibodies recognized epitopes in bands at approximate molecular weights of 12, 14, 23 and 25 kDa. RAST inhibition assays showed that the affinity‐purified proteins were able to inhibit the binding of serum IgE from peanut‐allergic individuals to solid‐phase CPE.

ISSN:0954-0105    

DOI:10.1080/09540109409354830

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor