Metabolite analysis

Estimation of dose from urinary metabolite analysis.59... 

Estimation of dose from urinary metabolite analysis From the analysis of volunteer s urine for 3,5,6-TCP, the amount of absorbed chlorpyrifos was determined for each individual volunteer. Table 5 summarizes the calculated chlorpyrifos dose based on analysis of urine samples. The average chlorpyrifos dose was estimated to be 7.07 pg/kg, 182% of the dose estimated using physical techniques. 

Maharjan, R. P. Ferenci,T. Global metabolite analysis the influence of extraction methodology on metabolome profiles of Escherichia coli. Anal. Biochem. 2003,313, 154-154. 

The development of high-power NMR (800 MHz) spectrometers permits the simple operation of LC-NMR for metabolite analysis. 

Despite this clearly outlined procedure, scientific progress in the field has been slow, as very few authors have as yet attempted environmental risk assessment of PhCs in water, focussing their attention, furthermore, mainly on parent compounds rather than their metabolites, on the effects of individual substances rather than mixtures on target organisms and on acute rather than chronic toxicity. In particular, metabolite analysis tended to be disregarded as their exposure is very difficult to assess due to a lack of consensus in the literature regarding excreted metabolite fractions moreover, analysis has shown that their relative contribution to the overall risk is typically low [99]. 

While the clinical use of MS/MS of hormonal steroids is new, metabolite analysis by gas chromatography (GC)-mass spectrometry (MS) has been available for 40 years, since few immunoassays were developed for urinary analytes. Profile analysis is a very powerful technique and it must be recognized that with few exceptions, all disorders of steroid synthesis and metabolism first had their metabolome defined... 

One final note that requires a discussion it is the mass and charge of a molecule that is measured in a mass spectrometer, not simply mass. However, with most small molecules, the charge is 1 and hence an m/z value is ml 1 or simply m. However, certain molecules have the potential to become multiply charged (i.e., proteins and peptides). Therefore multiply charged molecules could have multiple mass values at m/1, ml2, ml3 etc. Most metabolite analysis however is singly charged and as such simplifies this discussion. 

Finally, coexpression of many enzymes within a single cell will be important technique for the analysis of the balance of Phase I and Phase II enzymes on overall metabolism and/or toxicity of xenobiotics. The feasibility of this approach has been demonstrated with the development of MCL-5 cells which coexpress five cDNAs (Crespi et al., 1991c). However, an even greater multiplicity of enzyme coexpression is still needed and higher expression levels are necessary for routine use of such a system for metabolite analysis. 

A couple of additional experiments involving TMA-2 had been set up and started, but somehow never had enough fire to get completed. Studies on the optical isomers had gotten up to assays of 6 milligrams on each of the separate isomers, but had never been taken higher. The R isomer is much the more potent in rabbit assays, but the human comparisons remain unknown at present. Also, a study of the 14C labeled racemate (5 microcuries in 40 milligrams) was conducted with a view to metabolite analysis, but again, the project was abandoned before any results were obtained. In the rat, the 4-methoxyl carbon appeared as expired carbon dioxide to the extent of about 20%. And this is some four times the amount seen from either of the other two methoxyl carbon atoms. 

Quadrupole, Triple-Quadrupole, and Hybrid Linear Ion Trap Mass Spectrometers for Metabolite Analysis... 

Herman, J. L. (2005). The use of turbulent-flow chromatography and the isocratic focusing effect to achieve on-line cleanup and concentration of neat biological samples for low-level metabolite analysis. Rapid Commun. Mass Spectrom. 19 696-700. 

Lee, M. S. Kerns, E. H. 1998. High throughput drug metabolite analysis using LC/MS screening methods. British Mass Spectrometry Society 23rd Annual Meeting, University of Warrick, UK. 

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