Nucleoside Analogue Quantitation in Genomic DNA
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Solution Overview
Problem
Current methods lack the ability to accurately measure the incorporation of nucleoside analog DNA methyltransferase inhibitors, such as decitabine and azacitidine, into genomic DNA, which hinders the optimization of their efficacy and toxicity in cancer treatment due to variable drug incorporation and resistance mechanisms.
Innovation Solution
A method involving the extraction of nucleic acid from biological samples, digestion to dephosphorylated nucleotides, addition of stable heavy-isotope labeled internal standards, separation via high-pressure liquid chromatography, and quantification using mass spectrometry to determine the amount of drug incorporation into DNA, allowing for simultaneous measurement of DNA methylation levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods are used to measure drug incorporation, then the measurement process is simple, but the measurement precision and accuracy are insufficient
Solution Approach 1:
The patent introduces stable heavy-isotope labeled internal standards as intermediaries to enable accurate measurement of drug incorporation. These internal standards serve as reference compounds that co-elute with the analytes during chromatography, allowing for precise quantification by mass spectrometry while compensating for variations in sample preparation and analysis
Solution Approach 2:
The patent replaces conventional measurement approaches with mass spectrometry-based detection. This substitution enables highly sensitive and specific quantification of drug incorporation into DNA by measuring the mass-to-charge ratio of ionized molecules, providing superior measurement precision compared to traditional methods
2Measurement precision
If high-pressure liquid chromatography with porous graphite column is used, then the separation precision is improved, but the device complexity and operational difficulty increase
Solution Approach 1:
The patent employs a porous graphite analytical column for high-pressure liquid chromatography separation. The porous structure of the graphite column provides high surface area and specific adsorption properties that enable excellent resolution of nucleoside analogs from complex biological matrices, achieving superior separation precision
Solution Approach 2:
The patent utilizes high-pressure liquid chromatography with controlled flow rates, mobile phase composition, and temperature parameters to optimize separation. By adjusting these parameters, the method achieves baseline separation of drug metabolites and internal standards despite the increased operational complexity
3Measurement precision
If mass spectrometry is used for quantification, then the measurement precision and sensitivity are improved, but the device complexity and cost increase
Solution Approach 1:
The patent replaces conventional quantification methods with mass spectrometry detection. The mass spectrometer ionizes molecules and measures their mass-to-charge ratios, providing highly sensitive and specific quantification of drug incorporation into DNA with detection limits in the picomole range, far exceeding traditional analytical methods
Solution Approach 2:
The patent uses stable heavy-isotope labeled internal standards as mediators for mass spectrometry quantification. These internal standards co-elute with analytes and produce distinct mass spectral signals, enabling accurate quantification by comparing analyte-to-internal standard signal ratios, which compensates for ionization efficiency variations and matrix effects
4Measurement precision
If nucleic acid digestion to dephosphorylated nucleotides is performed, then the measurement accuracy of drug incorporation is improved, but the processing time and complexity increase
Solution Approach 1:
The patent performs preliminary digestion of nucleic acids to dephosphorylated nucleotides before analysis. This preliminary action converts complex nucleic acid structures into simpler, more analyzable nucleotide forms, enabling accurate measurement of drug incorporation while establishing a consistent baseline for quantification
Solution Approach 2:
The patent segments the complex nucleic acid molecule into individual nucleotide units through enzymatic digestion. This segmentation allows for the specific measurement of drug-containing nucleotides independent of the rest of the nucleic acid structure, improving measurement accuracy by isolating the analyte of interest
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method provides precise and accurate quantitation of drug incorporation into DNA, correlating with pharmacodynamic effects and enabling individualized exposure-response relationships, thereby enhancing the understanding and effectiveness of cancer therapy.
Implementation Method 1
adding the analyte to a mass spectrometer; and quantifying the amount of the analyte in the nucleic acid
Implementation Method 2
separating the analyte in the second sample using high pressure liquid chromatography through a porous graphite analytic column
Implementation Method 3
adding a stable heavy-isotope labeled internal standard to the first sample to form a second sample comprising an analyte
Data Source
AI summary
This application provides methods to quantitate drug incorporation into DNA and of simultaneously measuring DNA methylation levels. Drugs include nucleoside analog DNA methyltransferase inhibitors.