OTHER IMMUNOCHEMICAL TECHNIQUES

Other analytical methods of clinical interest that employ antibodies include cytochemical and agglutination assays. 

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Other immunochemical techniques, not applied to environmental samples as yet, could be interesting for the future analysis of these residues.112,113... 

During the last decade, immunoblotdng has become a versatile and essendal technique for any biochemically oriented research laboratory (6,7). As observed for the other immunochemical techniques described above, mediadon by avidin-biodn technology has served to improve signal intensides, to enhance sensidvity levels, and has contributed gready to the efficacy and versadlity of blotdng procedures. 

The use of immunoassays for the determination of pesticides and veterinary medicines in food animals has increased since the early 1990s. The advantages of simple analysis, quick results, and high throughput make immunoassays a powerful technique for problematic matrices commonly encountered in animal agriculture. Careful development and validation are required to obtain accurate results, however. This review has demonstrated that most immunochemical techniques have been designed for use with milk samples, but a number of applications have also been developed for liver and muscle samples. The development of immunoassay techniques for residue analysis in eggs has clearly not been pursued to the extent of other edible tissues. 

Fichtinger-Schepman AMJ, Dijt FJ, De Jong WH, van Oosterom AR, Berends F. In vivo cis-diamminedichloroplatinum(II)-DNA adduct formation and removal as measured with immunochemical techniques. In (Nicolini M, ed), Platinum and Other Metal Coordination Compounds in Cancer Chemotherapy 1988 Martinus Nijhoff Publishing Boston, pp. 32-46. 

Application of microbiological or immunochemical techniques offers the advantage of screening drug residues in foods with little or no previous sample preparation. Application, on the other hand, of physicochemical techniques, allows quantification and more tentative identification of residues in those samples found positive. The problem of analyzing for drug residues is complicated by the fact that it is not known whether residues exist, and if they exist, the type and quantity are not known. 

Immunochemical Techniques Developed for the Detection of Other Drugs... 

The enormous specificity and resolution of immunochemical techniques are responsible for their increasing application to problems in biochemistry and molecular biology. The ability to specifically measure picogram quantities of one molecule or to isolate milligram quantities of another is indeed awesome. However, as with most powerful techniques, these potentials are attainable only by discriminating application and careful use. Major aspects of immunochemical methodology are described along with some of their inherent problems. The discussion, however, is by no means complete. Some specialized immunochemical procedures are dealt with only briefly and the reader is referred to other relevant sources for a more complete discussion. 

The avidin-biotin technique is especially useful in double-labeling experiments. This can be done using two different enzymes in the final step, combined with two different andbody species (monoclonal and/ or polyclonal). One of the andbodies can be biodnylated and the other immunochemical reaction can be based on a different procedure (e.g., employing an antibody-enzyme conjugate). Alternatively, both antibodies can be biotinylated and the secondary reaction with the respective avidin-enzyme conjugate can be performed on different sides of an impermeant (e.g., plastic-embedded) tissue section. 

Immunochemical procedures provide an important supplement to the battery of available chemical and instrumental methods and can often yield new information not readily obtainable in other ways. Antibodies are extraordinary analytical reagents since they can have specificity for macromolecules (proteins, nucleic acids, and polysaccharides) as well as for small molecules belonging to almost every chemical class. In a field that is moving so rapidly, an exhaustive compilation of immunochemical techniques is neither possible nor practical. Our purpose is to provide the investigator with significant examples and sufficient background information so that he can properly assess and adapt these techniques to his research. 

Already in progress is a second volume that will supplement the topics presently covered and include other important techniques. Innovative and practical applications of immunochemical methods have been described in other volumes of this series. We have avoided duplication so far as possible, and have included a cross-reference bibliography for each section (see pp. 481-484) to direct the reader to related papers in other volumes. Subsequent volumes will be involved with the development and application of immunoassays for specific compounds as well as for different classes of compounds. 

It is also not entirely clear why the blood levels of individual enzymes in muscular dystrophy differ so widely. In some instances, even, there appears to be no increase. Thus blood AMP deaminase levels are barely raised (P8), and Rowland and co-workers (RIO) were unable to detect phosphofructokinase or myoglobin by enzymological or immunochemical techniques. The relative abundance of the enzyme in muscle is obviously important indeed, Dawson (D2) found that in vitro there was a good correlation between the amounts in muscle and the amounts leaking out. In Duchenne dystrophy, however, there is a poor parallel between the concentrations in muscle and blood (P8). The size and shape of an enzyme molecule would be expected to influence its rate of leakage, and a further factor is the attachment of an enzyme to intracellular structures there is some evidence that even the soluble enzymes of muscle may be, in some manner bound within the fibers (A2, H17). Probably other factors also are involved. 

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