Assays, microarray

Examples of biomarker assays operating at different levels are given in Table 4.2. The recent development of omics technology should provide strong support to this approach (Box 4.3). Microarray analysis, for instance, can give a time-related sequence of gene responses that relate to the cellular changes of toxicity. 

Additional information on biomarker approaches and new technologies, such as microarray assays, developed to address complex pollution problems... 

None of these compounds have been tested in a microarray assay... 

The methods for genome-wide analysis of ribosomal association are conceptually different from those for analysis of a single mRNA (e.g., northern analysis). While in assays of a single gene by northern analysis it is simple to compare the distribution of an mRNA in different fractions, in a genome-wide assay, the mRNAs are usually compared relative to others within the fraction. Because of that, it is important to analyze by northern analysis several mRNAs that appeared to be affected to different extents, and to compare the relative effects among this group between the microarrays and the northern analysis. 

Zichi D., Koga T., Greef C., Ostroff R., Petach H., Photoaptamer technology development of multiplexed microarray protein assays, Clin. Chem. 2002 48 1865-1868. 

A similar type of biotin-dendritic multimer also was used to boost sensitivity in DNA microarray detection by 100-fold over that obtainable using traditional avidin-biotin reagent systems (Stears, 2000 Striebel et al., 2004). With this system, a polyvalent biotin dendrimer is able to bind many labeled avidin or streptavidin molecules, which may carry enzymes or fluorescent probes for assay detection. In addition, if the biotinylated dendrimer and the streptavidin detection agent is added at the same time, then at the site of a captured analyte, the biotin-dendrimer conjugates can form huge multi-dendrimer complexes wherein avidin or streptavidin detection reagents bridge between more than one dendrimer. Thus, the use of multivalent biotin-dendrimers can become universal enhancers of DNA hybridization assays or immunoassay procedures. 

T.A. Joos, M. Schrenk, P. Hopfl, K. Kroger, U. Chowdhury, D. Stoll, D. Schomer, M. Durr, K. Herick, S. Rupp, K. Sohn, and H. Hammerle, A microarray enzyme-linked immunosorbent assay for autoimmune diagnostics. Electrophoresis 21, 2641-2650 (2000). 

The most common use of protein microarrays is in immunoassays. In particular, antibody-based immunoassays are the main stream of diagnostic assays due to their specificity. The assay usually runs in a multiplexed mode where the antibodies or other capture agents are immobilized and then exposed to a biological sample. There are four immunoassay formats direct binding, sandwich (ELISA), competitive, and displacement. Direct-binding and sandwich assays are the most common. There are some reports on the use of competitive assays and displacement assays, which are usually associated with high surface area/volume systems [72-76],... 

R.P. Ekins, Ligand assays from electrophoresis to miniaturized microarrays. Clin. Chem. 44, 2015-2030 (1998). 

In general, quantitative gene expression results obtained with microarray analyses correspond well to results obtained using other methods.11 However, quantitative data from microarrays are typically less reliable for genes that are very highly or very poorly expressed.12 In addition, microarrays are much less sensitive than real time PCR and RNAse protection assays.13 However, the ability to analyze most of the mRNA spe-... 

Immunoaffinity chromatography (IAC), 6 400—402 12 137, 145 Immunoanalyzers, automated, 14 150 Immunoassay(s), 14 135-159. See also Immunoassay- DNA probe hybrid assays Immunoassay methods Immuno(bio)sensors antibody-antigen reaction, 14 136-138 basic technology in, 14 138-140 chemiluminescent, 14 150-151 classification of, 14 140-153 design of, 14 139-140 enzyme, 14 143-148 fluorescence, 14 148-150 highly specific, 14 153 historical perspective on, 14 136 microarrays and, 14 156—157 microfluidics in, 26 968—969 monoclonal versus polyclonal antibodies in, 14 152-153... 

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