Definion Of Assay

Definition of Assay

Assay: An assay is an analysis done to determine:

1. The presence of a substance and the amount of that substance. Thus, an assay may be done for example to determine the level of thyroid hormones in the blood of a person suspected of being hypothyroid (or hyperthyroid).

2. The biological or pharmacological potency of a drug. For example, an assay may be done of a vaccine to determine its potency.

Assay is also used as a verb and has several related meanings in this role:

1. To try or attempt. For example, "she assayed this operation for the first time and so was understandably nervous."

2. To analyze a mixture for one or more of its components

3. To judge the value, the worth of something.

The words "assay" and "essay" are often confounded, a cardinal sin according to some word mavens. However, "assay" and "essay" share a common ancestry. Both words come from the French "essai" which in turn came from the Late Latin "exagium" meaning the "act of weighing".

http://www.medicinenet.com/script/main/art.asp?articlekey=8412

EXAMPLES:

Cytotoxicity Assays

Hepatocarcinoma Cytotoxicity Assay (MTT and LDH)

The Hepatocarcinoma Cytotoxicity Assay tests the cytotoxicity of nanoparticle formulations in human hepatocarcinoma cells (Hep G2). The protocol utilizes two methods for estimation of cytotoxicity, 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) reduction and lactate dehydrogenase (LDH) release (1, 2).

The MTT assay is a colorimetric assay that can assess the viability of cells by quantitation of the reduction of the yellow substrate MTT (4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) to a product that has a purple color. This assay can measure the cytotoxicity of a chemical or drug by determining the affect of treatment on cell viability. The Assay File represents an example for a MTT cytoxicity assay (MTT) performed on three nanoparticle samples, where 9 dilutions of each nanoparticle sample are exposed to porcine proximal tubule cells for three different times of exposure (6h, 2h, and 48 h) (3).

LDH is a cytoplasmic enzyme that is released into the cytoplasm upon cell lysis. The LDH assay is a measure of membrane integrity. The basis of the LDH assay: (1) LDH oxidizes lactate to pyruvate, (2) Pyruvate reacts with the tetrazolium salt INT to form formazan, and (3) the water-soluble formazan dye is detected spectrophotometrically (4,5).

Assay File Assay Factors Assay Measured Values Supporting Information

Hep G2 Hepatocarcinoma Cytotoxicity Assay (MTT)

• Time

• Cell Viability

• Hep G2 Hepatocarcinoma Cytotoxicity Assay Protocol

• Characterization of Nanoparticles for Therapeutics

• Dendrimer-Based MRI Contrast Agents

Hep G2 Hepatocarcinoma Cytotoxicity Assay (LDH)

• Time

• Cell Viability

• Hep G2 Hepatocarcinoma Cytotoxicity Assay Protocol

• Characterization of Nanoparticles for Therapeutics

• Dendrimer-Based MRI Contrast Agents

Caspase Apoptosis

Caspase Apoptosis assays monitor apoptosis by measuring the degree of the caspace (family of cysteine proteases) activity, an indicator of apoptosis. Caspase apoptosis assays measure the cleavage of the DEVD-AFC (Amino Tri-fluoromethyl Coumarin substrate to free AFC. Free AFC emits yellow-green fluorescence (1,2,6).

Assay File Assay Factors Assay Measured Values Supporting Information

Caspase Apoptosis

• Concentration

• Solvent Medium

• % Control Caspase Activity

• LLC-PK1 Kidney Cell Apotosis Assay

• Functionalized F

https://wiki.nci.nih.gov/display/ICR/Assay+File+Examples

Engineers and scientists write formal reports for many reasons, including the documentation of experiments and designs. As an engineer or scientist working on the design of an airplane seat, you might write several formal reports. One formal report might propose a new design for the seat. A second formal report might update the progress on the construction of a test seat. Yet another formal report might document tests performed on the design. Still another formal report would assess whether the new design should replace the existing design. In this last report, you would combine elements from all the previous reports. Note that this last report might appear as a research article, which is a special kind of formal report for a research audience.

For reference, this discussion includes a sample report [Bassett, 1998]. Also available is a short discussion of laboratory reports, design reports, progress reports, and theses and dissertations. Note that there will most likely be differences in format between the sample reports included here and the reports you are expected to write for your own classes. Nonetheless, these samples should provide you general guidelines for crafting the assignments in your own courses. Another aid to help you is a report checklistthat you can use during the revision stage of your report writing.

What distinguishes a formal report from an informal reporting of information? The answer lies not in the topics of formal reports, but in the expectations of the audiences for formal reports. In a formal report, the audience expects a methodical presentation of the subject that includes summaries of important points as well as appendices on tangential and secondary points. Note that the readers for a formal report are often two or more d

istinct audiences.

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