Immunoassay results

Because the protein analyte is endogenous to the plant, it can be difficult to demonstrate the efficiency of the extraction procedure. Ideally, an alternative detection method (e.g., Western blotting) is used for comparison with the immunoassay results. Another approach to addressing extraction efficiency is to demonstrate the recovery of each type of protein analyte from each type of food fraction by exhaustive extraction, i.e., repeatedly extracting the sample until no more of the protein is detected. " ... 

While in most instances the RCA microarray immunoassay results were comparable to published performance reports on commercial ELISA (Quan-tikine, R D Systems), there were notable exceptions in which ELISA appeared to out-perform the microarray by 10- to 50-fold sensitivity. Such differences may be due to variations in binding affinities exhibited by the particular capture antibodies employed in the assay. In studies involving lipopolysaccharide (LPS)-induced secretion of cytokines from human... 

Enzyme-Immunoassay Results with Clinically Documented Fishes. The data presented in Figure 1 indicate that the EIA procedure clearly differentiated between clinically documented toxic and non-toxic fishes of several different species (a) Parupeneus sp. (moana), 1 (b) shark, 1 (c) Sphyraena sp., 1 (d) Elagatis bipinnulatus (rainbow runner), 2 (e) Caranx sp. (Jack), 1 (f) Lutjanus sp. 

Reproducibility of immunoassay results can be adversely affected by variations in the chemical formulation of different lots of plastics used as the solid phase (see section on Solid Phase Materials). Therefore, use of a thin coating of one lot of plastic over a material like metal for millions of tests could be important in standardizing immunoassay techniques. Extremely small amounts of polycarbonate (or other plastics) are required for putting a thin coating on steel beads. Therefore, one small commercial lot of plastic (e.g., one 212 pound 4x8 foot sheet of polycarbonate) would be sufficient to prepare beads for over 100 million tests. Plastic solid phases employing Microtiter plates, test tubes, and polystyrene beads require relatively large quantities of plastic for fabrication and, con-... 

Valdes R Jr, Jortani SA. Unexpected suppression of immunoassay results by cross-reactivity now a demonstrated cause for concern. Clin Chem 2002 48(3) 405-6. 

Enzymes are nowadays the labels that are most used in immunoassay. Their main disadvantage is their susceptibility to interferences due to changes in assay conditions, e.g., pH, ionic strength, content of organic solvents. The addition of anti-microbial agents such as azides or mercury derivatives also can affect the enzyme activity when using peroxidase labels [96]. The presence of other catalysts in the sample can also have an effect on the enzyme immunoassay result, e.g., Cu(II) ions promote luminol chemiluminescence in the presence of hydrogen peroxide [16]. 

The best statistical acceptance/rejection criteria for immunoassay results have proved to be the use of confidence intervals for total measurement error (e.g., including both accuracy and precision) and equivalence testing procedures [15], and a 90% two-sided confidence interval has been proposed for the acceptance of immunoassay data [145]. Recoveries of 70-120% are considered acceptable according to US-EPA guidelines and the maximum permissible level of false negatives is 5% [38]. 

True positive specimens were defined as having immunoassay results equal to or greater than the specified cutoff concentration (100 or 50 pg/L) and >15 pg/L THCCOOH by GC-MS. Tme negative specimens had results less than the cutoff concentrations for the immunoassays and the GC-MS test. False positive samples had immunoassay results greater than or equal to the immunoassay cutoff concentration and <15 pg/L THCCOH by GC-MS. False negative samples had immunoassay results lower than the specified immunoassay cutoff concentration and >15 pg/L THCCOOH by GC-MS. 

Ismail AAA, Walker PL, Barth JH, Lewandowski KC, lones R, Burr WA. Wrong biochemistry results two case reports and observational study in 5310 patients on potentially misleading thyroid-stimulating hormone and gonadotropin immunoassay results. Clin Chem 2002 48 2023-9. 

Marks V. False-positive immunoassay results a multicenter survey of erroneous immunoassay results from assays of 74 analytes in 10 donors from 66 laboratories in seven countries. Clin Chem 2002 48 2008-16. 

Cytochrome P450 3A is primarily responsible for Tac metabolism and nine metabolites have been isolated from human blood and rat bile, or produced in vitro by human or animal liver microsomes. Tac metabolites in the blood of liver and kidney transplant patients totaled 42% to 45% of the Tac concentration. AH of the metabolites, except for 31-O-desmethyl Tac, a minor Tac metabolite, have little immunosuppressive activity. The latter has in vitro immunosuppressive activity comparable with that of the parent drug. The total immunosuppressive activity of the metabolites is therefore negligible in transplant patients. However, in liver transplant patients with hyperbilirubinemia, there can be significant high bias in the immunoassay results because of metabolite accumulation that results from impaired bile clearance. ... 

Dufour DR, Talastas M, Fernandez M, Harris B, Strader D, Seeff L. Low positive anti-hepatitis C virus enzyme immunoassay results An important predictor of low likelihood of hepatitis C infection. Clin Chem 2003 49 479-86. 

Howanitz J, Review of the influence of polypeptide hormone forms of immunoassay results. Arch Pathol... 

Most of these measurements are still routinely perfonned with immunoassays because of their simplicity, rapidity and relatively low cost, and despite occasional concerns about their reliability and validity. Serum total T has also been quantitated by gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS) and LC-MS-MS. MS-based methods are often used in research smdies or to confirm immunoassay results. The advantage of chromatography coupled with MS is the high specificity not available with immunoassays because they are susceptible to cross-reactions. An immunoassay might measure a host of structurally related compounds in addition to the target analyte. 

The prolactin immunoassay results shown in Table 2 demonstrate the ability to miniaturize HTRF assays. The recommended volume of 300 pL was used in the 96-well plate. This was reduced to 75 pL for the 384-well assay. The result of most importance is the ratio. For every prolactin standard, the ratio in the 384-well is the same as in the 96-well. It should also be noted that although the volume in the 384-well was only 25% of the 96-well, the fluorescent counts were 50%. This results from the difference in the ratio of the liquid column height to volume of the two plates. This presents the possibility that an optimized microplate geometry will allow a degree of miniaturization with HTRF that is not possible with other labels. 

Production of antibodies and demonstration of immunogenic responses does not necessarily mean that animals will be protected against challenge of the disease agent. The relationship of immunoassay results to protection is never straightforward because of the many other factors involved in immunological response, e.g., cellular immunity. 

The two methods compared well with a rank correlation coefficient of 0.90 for immunoassay results less than 5 ug/L (micrograms per liter). The presence or absence of triazine herbicides can be determined visually at concentrations of about 0.5 ug/L, and the detection limit can be lowered to about 0.2 ug/L with a spectrophotometer. The median pre-application and fall concentrations of triazine herbicides in the streams were determined by immunoassay to be less than 0.2 ug/L and 0.3 ug/L, respectively, compared with a post-application median of 3.4 ug/L. Immunoassay appears to be a rapid, reliable, and low-cost analytical screening method for detecting triazine herbicides in water. 

Table II. Comparison of immunoassay results obtained on blind duplicate samples by a single laboratory (within lab) and results on samples analyzed by two different laboratories (between labs)...

Immunoassay bv Visual Comparison. During the course of this study, 421 Immunoassay analyses were made by visual comparison as described previously in this paper. Immunoassay analyses on these same samples were also made with the aid of a spectrophotometer in addition, 180 of the samples were analyzed by GC/MS. A comparison of the visual analysis with spectrophotometrlc Immunoassay results and GS-MS results is given in Table III. The results Indicate a visual detection limit for Immunoassay of about 0.5 ug/L. For the 173 samples in which the visual analysis results were negative, 98 percent of the spectrophotometrlc analyses were less than 0.5 ug/L. Also, for 45 of these samples that were analyzed by GC/MS, 98 percent contained less than 0.5 ug/L of atrazlne. 

Table III. Comparison of visual Immunoassay results for presence or absence of triazlne herbicides with Immunoassay results obtained from spectrophotometrlc analysis and with...

Immunoassay results Immunoassay results Atrazlne results... 

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