Biological assessment metabolites

An environmental protocol has been developed to assess the significance of newly discovered hazardous substances that might enter soil, water, and the food chain. Using established laboratory procedures and C-labeled 2,3,7,8-tetra-chlorodibenzo-p-dioxin (TCDD), gas chromatography, and mass spectrometry, we determined mobility of TCDD by soil TLC in five soils, rate and amount of plant uptake in oats and soybeans, photodecomposition rate and nature of the products, persistence in two soils at 1,10, and 100 ppm, and metabolism rate in soils. We found that TCDD is immobile in soils, not readily taken up by plants, subject to photodecomposition, persistent in soils, and slowly degraded in soils to polar metabolites. Subsequent studies revealed that the environmental contamination by TCDD is extremely small and not detectable in biological samples. 

Pyrethroid insecticides are rapidly metabolized to their inactive acids and alcohol components, which are excreted primarily in urine. A small portion of the absorbed compounds is excreted unchanged. Occupational exposure to pyrethroid insecticides can be assessed by measuring intact compounds or their metabolites in urine. Biological indicators of internal dose in exposed subjects are reported in Table 7. Due to their rapid metabolism, determination of blood concentrations can only be used to reveal recent high-level exposures. 

UV Filters Biodegradation by Fungi, Metabolites Identification and Biological Activity Assessment... 

The National Institutes of Health (NIH) has characterized "[t]he general aim of metabolomics. .. to identify, measure and interpret the complex, time-related concentration, activity and flux of endogenous metabolites in cells, tissues and other biosamples such as blood, urine and saliva."3 Taken together, the three "omics" disciplines represent a systemic and powerful approach to mapping cellular networks, allowing for faster and more predictive biology in terms of risk assessment, potential therapeutic benefit, as well as diagnosis. 

Methods for Parent Compound and Metabolites in Biological Materials. No information is available concerning the analysis of isophorone in biological materials. If information were available, it would allow both investigators and reviewers to assess the accuracy and uncertainty of the methods used. Furthermore, the ready availability of tested analytical methods would permit a standardized approach to the analysis of biological materials and allow a comparison of the levels of exposure with the possible health effects in humans. 

Regulatory requirements in the field of drug residues analysis are limited, in most cases, to the identification of only the major metabolites. Quantitative selection of major over minor metabolites is certainly devoid of rational biological ground, since several studies have shown that the toxic metabolites are usually transitory and often present in small quantities. However, isolation and identification of all these metabolites are difficult and proper assessment of the toxicity of drug residues is still a real challenge. 

The profiles of biological interference ions in Fig. 6.11 can serve as a guide to predict the effectiveness of MDF for a drug metabolite sample or to assess whether a stringent filter parameter should be used to facilitate detection of drug metabolite ions. The mass defect window of a MDF and its chosen mass range are set based on the relationship of a... 

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