Enzyme-linked immunosorbent assay ELISA kits

The cultured root segments were divided into proximal, distal and newly developed lateral root parts and their endogenous lAA levels were periodically analyzed using enzyme-linked immunosorbent assay (ELISA) kits for lAA (PHYTODETEK iAA, Idetek Inc., USA) according to the procedure of Weiler et al. [39]. The lAA levels in the root segments are indicated in Fig. (26). The lAA levels in the roots cultured on HF B5 medium that initiated shoot formation increased once at day 9 and consequently decreased in both proximal and distal parts. On the other hand, lAA levels in proximal part of the roots cultured in the presence of 0.5 mg/1 TIBA increased along with the culture period. The roots cultured on the MS medium containing 0.5 mg/1 NAA (source for the experiments) accumulated low amounts of lAA and the lateral roots did not accumulate detectable amounts of lAA in all the cases. 

Currently, various practical methods can be employed to accurately measure the amounts of leukotrienes and lipoxins in biological samples. Enzyme-linked immunosorbent assay (ELISA) kits, for example, are available from commercial sources and display both high specificity and high sensitivity (up to the low ng/pg range). These provide the quickest detection of material released in incubation supernatants, or derived from cellular material. They are complemented by more refined and complex, yet widely employed, approaches based on chromatographic and/or spectroscopic analyses. 

Among the high number of immunoassay techniques, the enzyme-linked immunosorbent assays (ELISAs) combined with a colorimetric end point measurement are the most widely used. These techniques have also been introduced on the market as PCBs ELISA kits by many companies (see Table 25.2). 

FDA approves the first enzyme linked immunosorbent assay (ELISA) test kit to screen for antibodies to HIV... 

Antibodies are a powerful and essential tool in scientific laboratories being used in an array of applications such as immuno-histochemistry, immunobloting, immunoprecipitation and enzyme-linked immunosorbent assays (ELISA). The different sources for antibodies include polyclonal antisera from immunized animals and monoclonal antibodies from cells in culture or from ascites in animals. Both polyclonal and monoclonal antibodies have their advantages, and or disadvantages, but in general the production of monoclonal antibodies is more time consuming and requires tissue culture facilities and skills. The use of either monoclonal or polyclonal antibodies in some of the applications may require that the antibody is in a purified form. They can be purified by a variety of methods described in the next few chapters. The availability of commercially available kits primarily designed for the purification of IgG and IgM classes of antibodies derived from all common animal species should also be mentioned. 

The use of immunoassay techniques for the determination of PAHs has been reviewed. Immunoassay is based on the coupling of a specific biological antibody in the detection device with the analyte either directly in water or extracted from solid samples and diluted in buffer solution. Enzyme-linked immunosorbent assay (ELISA) is the most common immunoassay technique employed in commercially available test kits. Water samples or soil extracts are added with an enzyme conjugate reagent to immobilized antibodies where the conjugate competes with PAHs for binding to the antibodies. ELISA test kit sensitivity and crossreactivity depends on the PAH used to raise the antibody. Antiphenanthrene or antffluoranthene antibodies raised in host animals are the most commonly employed. Test kits will be most sensitive to the PAH from which the antibody was... 

TNF-a Levels. TNF-a levels of the cell-free supernatant were determined by an enzyme-linked immunosorbent assay (ELISA) using commercial ELISA kits (BioSource International, Camarillo, CA). The color developed was measured by... 

IMSs have been employed as detectors for well-established methods for the determination of bacteria and enzyme-linked immunosorbent assays (ELISA). In ELISA methods, primary antibodies attach to epitopes on the bacterial wall. Each antibody has a structure containing numerous epitopes that can be associated with a secondary antibody. The secondary antibody also has a region with enzymatic activity. This enzymatic region is able to react with a substrate to cleave a product that either is colored and can be determined by a spectrophotometer or is volatile and can be determined by headspace analysis. In the method developed by Snyder et al. and quantitatively explored by Smith et al.," the final product exhibited a distinctive negative product ion peak, as observed with a mobility spectrometer. This was accomplished with the widely deployed military-grade CAM, which was used without modification and suggested that it could serve as a potential bacteria analyzer, provided reagent kits and an inlet adaptor were also distributed. 

As mentioned above, GC and LC techniques (and GC-MS and LC-MS in particular) represent the major determinative approaches used in current MMRMs. Other, much less widely applicable and applied techniques include (1) capillary electrophoresis and capillary electrochromatography (2) thin-layer chromatography and (3) an array of immunoassays, such as immunosensors and enzyme-linked immunosorbent assay (ELISA). Immunoassays are, however, relatively useful for sensitive and rather rapid and inexpensive screening (followed by a confirmatory method in the case of a positive response) of selected pesticides for which ELISA kits or sensors are available. 

Enzyme-linked immunosorbent assays (ELISAs) in kit form are most widely used giving relatively rapid and inexpensive methods for multispecies identification. A typical format for such an ELISA is to coat different strips of the normal 12 x 8-well plate with antisera formed against serum albumin of the various species of interest. An extract of the meat product is added to the antibody-coated wells, incubated to ensure antibody binding of the serum albumin, and, after washing, a second antibody coupled with enzyme is introduced. The sandwich is visualized by addition of a substrate to the enzyme. ELISAs have been developed, also, for meat species identification in cooked meat products. These ELISAs are quite specific and sensitive ( 1% of each species can be detected) but are qualitative, or at best, semiquanti-tative. 

The ELISA (enzyme-linked immunosorbent assay) test kit for sulfentrazone and SCA residues in groundwater is developed with limit of quantitation (LOQ)... 

Concerning not all kits are created equal, there are two dimensions. First, some kits are really better than others. Second, a class of kits maybe excellent in a general sense, but some differences in their components and design may render them more robust for a particular application. For example, cyclic AMP can be measured using an enzyme-linked immunosorbent assay (ELISA) strategy. While all use the excellent ELISA platform, they can differ in the effect exerted by putative interferents in the sample. Thus, for a particular sample, one kit may work considerably better than another. 

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