Cell based bioassay

Through fractionating WWTW effluents and screening those fractions with cell-based bioassays responsive to estrogens, the natural steroidal estrogens Ej and... 

In addition to its use in quantitating the product, ELISA can also be used as a readout tool for cell-based bioassays or other assays that measure a biological activity conferred by the drug product. The end point of the bioassay may be a... 

Connor K, Harris M, Edwards M, Budinsky R, Clark G, Chu A, Finley B, Rowlands J. The influence of diet on AH receptor activity in human blood measured with a cell-based bioassay Evidence for naturally occurring AH receptor ligand activity in vivo. 2006 in press. 

In the absence of an unambiguous history of ricin exposure, the preferred diagnostic method is specific immunoassay of ricin in serum, respiratory secretions, or other clinical samples associated with poisoning. Most of the methods described for ricin detection are experimental or are under development. The CDC and the Federal Laboratory Response Network have the capability to detect ricin in environmental specimens using validated polymerase chain reaction (PCR) tests and time-resolved immunofluorescence assays, with cell-based bioassays to confirm ricin activity. The U.S. Department of Defense has produced experimental field immunoassays, but commercial distribution of field test kits currently is limited. 

Cell-Based Bioassay For a cell-based Nab bioassay, treated cells respond directly or indirectly to the drug in a concentration-dependent manner. Possible biological responses of the cells to chug treatment include cell proliferation, apoptosis, phosphorylation, chemokine release, and expression of proteins or genes [15,22,28 30]. These responses may by quantitated by techniques such as immunoassay, multiplex assays [31], flow cytometry [23], and gene expression profiling [32]. 

In contrast to the CLB assay format, cell-based bioassays are more complex, time, consuming, costly, and often are less sensitive. However, it is important to note that this methodology is a functional assay and, thus, demonstrates neutralization of a biological response. It is argued by some that a functional end point more closely mimics in vivo physiological responses [15]. 

Wei, X., Swanson, S.J., and Gupta, S. (2004) Development and validation of a cell based bioassay for the detection of neutralizing antibodies against recombinant human erythro poietin in clinical studies. Journal of Immunological Methods, 293, 115 126. 

Potency. Binding assays for quantitation use the binding of at least two molecules to form an interaction that withstands multiple washing steps, and they are the least variable [75]. Cell-based bioassays for potency use a cell line mixed with a sample to generate a cellular response that is quantified [75]. They have more variability [75] and are tricky to use to measure potency because the CV often is >30% [2]. Whole animal assays for potency are time-consuming and highly variable [75], and they have the typical disadvantages of in vivo tests in that they are expensive, inaccurate, slow, and raise animal ethics issues [19]. 

There is a clear trend today within the bioanalytical and biomedical fields toward more frequent use of cell-based studies. The dimensions of microfluidic systems are well matched to meet the demand on cell-based systems. Still, new methods are needed that can efficiently handle and manipulate cells in those formats. Examples have already been given in this chapter where acoustic forces are used to trap and manipulate cells. The device in Figure 44.22 has been forther developed for use in cell-based bioassays. The temperature characteristics of the device have been examined to be able to control the temperature during the cell experiments. The major source of heat in the acoustic resonance systems presented here is the power dissipation in the transducer itself. The power dissipation follows a... 

A cell-based bioassay procedure generally includes cell growth in suspension or adherent cultures for several days/weeks. In a typical assay, cells are activated/inhibited with the therapeutic protein of interest in a multiwell assay... 

Because PCR-based assays cannot directly detect the toxin protein, cell-based bioassays are sometimes used to confirm the intact toxin-killing activity of ricin in environmental samples (Brzezinski and Craft, 2007). 

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