Enzyme immunoassay, function

Assays of ciguatoxin. Determination of ciguatoxin levels in fish was carried out in many laboratories by mouse assays. Enzyme immunoassay to screen inedible fish has been proposed by Hokama (9). No specific chemical assay has been developed, as information on functional groups suitable for fluorescence labeling is not available. Analyses conducted in the authors laboratory on remnant fish retrieved from patients meals indicated that ciguatoxin content as low level as 1 ppb could cause intoxication in adults. An extremely high sensitivity and a sophisticated pretreatment method will be required for designing a fluorometric determination method for the toxin. 

Newman DJ, Price CP (1999) Renal function and nitrogen metabolites. In Burris CA, Ashwood ER (eds) Tietz Textbook of Clinical Chemistry, 3rd edn. W.B. Saunders Company, Philadelphia, pp 1204-1270 Pergande M, Jung K (1993) Sandwich enzyme immunoassay of cystatin C in serum with commercially available antibodies. Clin Chem 39 1885-1890... 

This relationship is established by measurement of samples with known amounts of analyte (calibrators). One may distinguish between solutions of pure chemical standards and samples with known amounts of analyte present in the typical matrix that is to be measured (e.g., human serum). The first situation applies typically to a reference measurement procedure, which is not influenced by matrix effects, and the second case corresponds typically to a field method that often is influenced by matrix components and so preferably is calibrated using the relevant matrix. Calibration functions may be linear or curved, and in the case of immunoassays often of a special form (e.g., modeled by the four-parameter logistic curve) This model (logistic in log x) has been used for both radioimmunoassay and enzyme immunoassay techniques and can be written in several forms as shown (Table 14-1). Nonlinear regression analysis is applied to estimate the relationship, or a logit transforma-... 

Bioassays for BT toxin are sensitive because the test animals function as a concentrator and a detector simultaneously. When exposed to very low concentrations, the toxin is accumulated as the animal feeds over a period of days. Compared to immunoassays, bioassays for the BT toxins are generally 50-100 times more sensitive (Table II). As with other residue procedures, sample work-up can be employed to extend the detection limits of an enzyme immunoassay and to remove interfering materials at the same time. Such work up will be essential if immunoassays are to be as sensitive as bioassays using filter feeding organisms. 

Cao, C., and Sim, SJ. (2007) Signal enhancement of surface plasmon resonance immunoassay using enzyme precipitation functionalized gold nanoparticles a femto molar level measurement of anti glutamic acid decarboxylase antibody. Biosensors and Bioelectronics, 22, 1874 1880. 

A. Specific levels. Blood levels are not commonly available. Cannabinoid metabolites may be detected in the urine by enzyme immunoassay for up to several days after single acute exposure or weeks after chronic THC exposure. Urine levels do not correlate with degree of intoxication or functional impairment. Hemp and hemp seed products (eg, hemp seed nutrition bars) may provide alternative explanations for positive urine testing. While barely capable of causing a tme positive for THC metabolite, they have no phanoacologic effect. 

The Emneus group in Denmark has reported the sensing of atrazine in surface water using microfluidic enzyme immunoassay and chemiluminescence as the transduction technique [19]. Silicon microchips were functionalized with proteins A and G via a hydrophilic polymer layer. An affinity capture competitive immunoassay was performed using a mixture of enzyme tracer [horseradish peroxidase (HRP)], atrazine sample, and antiatra-zine antibody which was subsequently injected on the microchannel, followed by addition of the substrate mixture [luminol/p-iodophenol (PIP)/H202]. Chemiluminescent oxidation of luminol/PIP/H202 in the presence of HRP enzyme was monitored via PMT. 

A drug which, by its actions on the heart, increases cardiac output and which is therefore used in the treatment of heart failure. It has to be used cautiously because of toxic effects. Elderly patients are particularly sensitive and overdosage occurs frequently, probably due to impaired renal function. Measurement of serum levels is therefore a useful guide to treatment. It can be measured by radioimmunoassay or enzyme-immunoassay. 

There should be specific, saturable binding to the receptor, accompanied by pharmacological characteristics appropriate to the functional effects, demonstrable using a radioactive, eg, tritium or iodine-125, ligand to label the receptor. Radioligand binding assays (1,6) have become a significant means by which to identify and characterize receptors and enzymes (see Immunoassays Radioactive tracers). Isolation of the receptor or expression of the receptor in another cell, eg, an oocyte can be used to confirm the existence of a discrete entity. 

Liposome conjugates may be used in various immunoassay procedures. The lipid vesicle can provide a multivalent surface to accommodate numerous antigen-antibody interactions and thus increase the sensitivity of an assay. At the same time, it can function as a vessel to carry encapsulated detection components needed for the assay system. This type of enzyme-linked immunosorbent assay (ELISA) is called a liposome immunosorbent assay or LISA. One method of using liposomes in an immunoassay is to modify the surface so that it can interact to form biotin-avidin or biotin-streptavidin complexes. The avidin-biotin interaction can be used to increase detectability or sensitivity in immunoassay tests (Chapter 23) (Savage et al., 1992). 

MEGX is readily detected by HPLC and fluorescence polarization immunoassay techniques [14,21,25,40,41]. The test is simple, normally requiring a onetime blood sampling, and informative because it depends on the capacity of the hepatic enzymes to metabolize lidocaine. While the analysis of lidocaine metabolites is rapid, this method has not been adapted for continuous hepatic function monitoring, which may be possible with the radiolabeled analogues such as Tc-Sn-lidocaine iminodiacetic acid [42]. 

Additional reports include the covalent bonding of antibodies to functionalized sol-gel films55, the entrapment of polyclonal fluorescein56, the development of a sol-gel enzyme-linked immunosorbent assay (ELISA) test for antigenic parasitic protozoa57 and an immunoassay for the detection of 1-nitropyrene58. 

We have measured FSH in unextracted urine on an AxSYM random-access immunoassay analyzer (Abbott laboratories, Abbott Park, IL) with a MEIA (microparticle enzyme immuno assay) reagent kit. In order to correct for dilution, creatinine was measured, and the urinary FSH was normalized for creatinine concentration. Urine and serum samples were obtained from 40 women between 32 and 55 years of age. All women were healthy, except for a benign gynecological illness for which they were admitted to our hospital. All women had normal renal function. On the day of operation, we took six serum samples from each patient, each at least an hour apart, in order to calculate the mean serum FSH concentration. During the same day, we collected an early-morning urine sample, 24-h urine sample, and a random void urine sample. 

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