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DCL’s Bile Acids offers several significant analytical and ease of use enhancements over classic NAD/NBT bile acids methods including a vastly improved interference profile and superior low end sensitivity. DCL is able to achieve these performance gains by utilizing the latest developments in clinical enzymology to produce a unique recycling system that amplifies the absorbance change produced by the relatively few bile acid molecules present in the fasting state. Through the use of a mixture of NADH and an analog of the NAD co-enzyme (Thio-NADH), DCL Bile Acids combines a separate "indicator" and "regeneration" reaction to create a robust amplification system. Indicator Reaction In this reaction, bile acids in the patient's sample are oxidized by 3-α-hydroxysteroid
dehydrogenase yielding oxidized bile acids and reduced co-enzyme. In some ways,
this reaction looks like the analytical step of the NAD/NBT method. Thio-NAD is in excess and, under analytical conditions, the reaction proceeds rapidly to the right and is essentially irreversible as far as Thio-NAD is concerned. While Thio-NADH has a larger absorbance per molecule than NADH, the color change produced by this reaction alone would not be enough to provide optimal analytical performance. The key to the sensitivity of the test and the amplification process is the next step, the regeneration reaction. Regeneration Reaction Oxidized bile acids generated in the indicator reaction above are "cycled" back in this reaction.
The Amplification Reaction System (Indicator/Regeneration Reactions combined) When the two reactions are combined, the same molecule of bile acid will be oxidized and reduced many times generating many molecules of Thio-NAD for each molecule of bile acid. The rate of absorbance change at 405 nm is monitored spectrophotometrically and is directly proportional to the concentration of bile acids in the patient's serum. Since many molecules of Thio-NAD are generated for each molecule of bile acid present in the patient's specimen, DCL’s Bile Acids assay provides far superior analytical performance to previous methods.
For Veterinary Use Only |
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