摘要:

Human milk samples (80) collected from 10 different cities in Egypt were tested for aldrin/dieldrin using an indirect enzyme‐linked immunosorbent assay (ELISA). Pesticides were detected in 73 of the 80 samples (91.25%) at levels ranging from 0.005 to 28 μg ml‐1. These results present evidence for the persistence (or continued use) of these pesticides in Egyptian agriculture and their transmission through the food chain. More significantly the levels of pesticide in maternal milk (0.006–28 ppm) represent an unacceptably high level for infant intake; the maximum average daily intake is 0.0001 mg kg‐1body weight (WHO, 1972).

ISSN:0954-0105    

DOI:10.1080/09540109509354860

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

2‐(2‐Mercapto‐5‐methyl‐1,3,2‐dioxaphosphorinan‐5‐yl,2‐sulphide)methoxyacetic acid has been synthesized and used to prepare an azinphos hapten and protein conjugates. Monoclonal antibodies of high affinity against the pesticide azinphos‐methyl were prepared from mice immunized with the hapten‐ovalbumin conjugate. The best monoclonal antibody could be used in an indirect enzyme‐linked immunosorbent assay (ELISA) to quantify azinphos‐methyl at concentrations from 50 pg ml‐1to 2 ng ml‐1(2.5–100 pg/assay). The corresponding limit of detection of the pesticide was less than 40 pg ml‐1. Only the closely related pesticide azinphos‐ethyl showed any appreciable cross‐reactivity in this assay.

ISSN:0954-0105    

DOI:10.1080/09540109509354861

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Polyclonal antibodies against norsolorinic acid reductase (NSR), an enzyme responsible for the conversion of norsolorinic acid to averantin in the early stage of aflatoxin biosynthesis, were produced after immunizing rabbits with a semi‐purified NSR preparation. Immunochemical analysis of the enzyme extracts fromAspergillus parasiticusrevealed that the antibodies reacted with several protein species, including bands corresponding to NSR activity. The ammonium sulfate‐cut IgG was further purified by passing it through a column armed with protein fractions containing immunoreactivity, but no enzyme activity, isolated from theA. parasiticusextracts that had been subjected to Sepharose gel filtration. After subtractive affinity chromatography, the purified antiserum reacted primarily with two protein bands (of molecular weight 43 and 48 kDa) and was capable of neutralizing the NSR activity. Enzyme‐linked immunosorbent assay (ELISA) analysis of various fungal extracts showed that the purified antiserum was highly specific for the enzyme.

ISSN:0954-0105    

DOI:10.1080/09540109509354862

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Polyclonal antisera specific for ochratoxin A (OA) were developed in laying‐hens and rabbits immunized with OA conjugated to bovine serum albumin. The rabbits and layinghens were immunized and tested under parallel conditions. OA‐specific antiserum activity was monitored using an indirect, competitive enzyme‐linked immunosorbent assay (cELISA). Rabbits and hens produced OA‐specific antisera within the first 51 days of the immunization schedule. The rabbits consistently produced OA antisera in 10‐fold higher amounts than the laying‐hens. Rabbit and laying‐hen antisera were found to be equally specific at most times in the immunization schedule for ochratoxins B and C, but not α. Antisera from both sources could be used to quantify OA in spiked wheat. The rabbit antisera could reproducibly detect OA at concentrations of 3 μg kg‐1or more, whereas antisera from hens could only detect 50 μg kg‐1or more. Similar results were obtained when OA was quantified in spiked wheat with both antisera when assayed at three different pH values (pH 6.0, 7.0 and 8.0). The optimal assay pH for the specific quantification of OA in wheat was 7.0. These studies suggest that rabbit antiserum is superior to hen antiserum in its ability to quantify OA in wheat. The sera from both animals, however, had similar cross‐reactivities with structurally related compounds.

ISSN:0954-0105    

DOI:10.1080/09540109509354863

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Hen egg‐white avidin inhibited the proliferative responses of mouse spleen cells stimulated by both concanavalin A (Con A) and pokeweed mitogen. It also inhibited mitogen‐induced proliferation of rabbit Peyer's patch cells. The Con A‐induced proliferation of spleen cells was inhibited by streptavidin without α‐D‐mannose residues as well as by egg‐white avidin with α‐D‐mannose residues. Egg‐white avidin was found to bind directly to spleen cells, but it had no cytotoxic activity against spleen cells or Peyer's patch cells. Egg‐white avidin did not appear to inhibit the formation of cytokines required for Con A‐induced spleen cell proliferation or to induce the production of growth‐inhibiting cytokines. On the other hand, egg‐white avidin's inhibitory effect on Con A‐induced spleen cell proliferation decreased as the time to addition of egg‐white avidin increased, and was lowest when the protein was added after 10 h of spleen cell cultivation with Con A. Spleen cells cultured with Con A resulted in a significant reactivity with anti‐interleukin‐2 (IL‐2) receptor antibody, whereas the addition of egg‐white avidin to the culture of Con A‐stimulated spleen cells noticeably reduced the reactivity. These findings suggest that the suppression of Con A‐induced proliferation of mouse spleen cells by hen egg‐white avidin occurs, at least in part, through the inhibition of binding of IL‐2 to its receptors on Con A‐activated spleen lymphocytes because of binding of the avidin to spleen lymphocytes or through the inhibition of IL‐2 receptor expression on the spleen lymphocytes.

ISSN:0954-0105    

DOI:10.1080/09540109509354864

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This article traces the development of antibody‐based methods in food microbiology from the earliestin vitroobservations of antibody binding. The evolution of methods from agglutination and precipitation via labelled‐antibody assays and immunocapture techniques to emerging instruments such as biosensors and flow‐cytometers is covered, including the potential for on‐line detection during food production. The principles of the methods are illustrated. Examples are given of the application of these techniques to the detection of pathogens and bacterial toxins. The relative merits of the methods for current and future use are discussed.

ISSN:0954-0105    

DOI:10.1080/09540109509354865

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Both polyclonal and monoclonal antibodies have been developed toPseudomonas solanacearum,the causative agent of bacterial wilt. When used in an indirect enzyme‐linked immunosorbent assay, the polyclonal antibodies detected as few as1 X 104bacterial cells ml‐1in infected plant or soil samples, but they could not distinguish betweenP. solanacearum, P. celebensis, P. syzygiiandP. picketti.The monoclonal antibodies developed had differing specificities, but, using selective immunization schedules, several were obtained which no longer cross‐reacted with closely related bacteria. These monoclonal antibodies were not as sensitive as the polyclonal antibodies and were only able to detect down to 1 X 106cells ml‐1.

ISSN:0954-0105    

DOI:10.1080/09540109509354866

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Aspergillus ochraceus Wilhelm is a common contaminant of stored foods, especially cereal grains, which produces the mycotoxin, ochratoxin A (OA). Solid‐phase immunoassays (enzyme‐linked immunosorbent assay [ELISA] and immunoblotting), utilizing antibodies raised in rabbits toA. ochraceusexoantigens (ExAgs, a mixture of extracellular macromolecules), were evaluated for their ability to provide an index of the degree ofA. ochraceuscontamination in cereals. A.ochraceuscould be readily detected with a minimal degree of interference or cross‐reactivity from the wheat matrix or from other fungal species naturally present in wheat. The ELISA was sensitive, with the limits of detection for ExAgs being as low as 50 ng ml‐1. The amounts of A.ochraceusExAgs detected in wheat that was naturally molded and inoculated with A.ochraceuscorrelated favorably with other parameters indicative of the presence of the fungus. These parameters included the amount of OA (r=0.93P <0.05), the percentage of A.ochraceusinfection (r=0.89P < 0.05),the number of colony‐forming units(r=0.68P <0.05) and the glucosamine content (r=0.64P <0.05). Immunoblotting patterns of ExAgs extracted from liquid and wheat cultures of A.ochraceusdemonstrated that ExAgs consisted of several antigenic components, with the immunodominant ones having molecular weights of approximately 20 or 30 kDa. The concentration of particular components appeared to be influenced by the media on whichA. ochraceuswas cultivated. The data suggest that the immunoassays developed for A.ochraceusExAgs can be used for the identification and quantitation of this fungus in grain.

ISSN:0954-0105    

DOI:10.1080/09540109509354867

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

ISSN:0954-0105    

DOI:10.1080/09540109509354859

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor