Small biomarker molecules

Another example is the accurate determination of small biomarker molecules in blood. Detection of low-abundance-low-molecular-weight (MW) biomarkers (small molecules or peptides) in blood, using mass spectrometry, can often be challenging. These low-MW molecules tend to undergo noncovalent... 

A very interesting subject is the application of analytical pyrolysis for the study of biomarkers in extraterrestrial samples [2], Several meteorites and lunar samples were studied using this technique. Also, Viking Lander used a Py-GC/MS system to explore the Martian atmosphere and surface [74], Commonly, a stepped pyrolysis technique has been used in these studies to determine organic components in an inorganic matrix [75], The procedure involves a set of four or five temperatures that allow the analysis of trapped gases, analysis of small volatile molecules, and the performance of true pyrolysis on macromolecules. 

Intact-cell MALDI-TOF analysis offers several attractive features for rapid screening of bacterial collections. Analysis is performed directly on the cells after minimal sample preparation, and data acquisition is complete in only a matter of minutes. Intact biomarkers are introduced into the MALDI-TOF instrument under these conditions. Whether the observed biomarker molecules are desorbed directly from the surface of the cell wall or are extracted from the cells and co-crystallized with the matrix is currently unresolved, but MALDI spectra of intact bacteria generally contain a large number of peaks in the mass range 1-20 kDa [31]. For bacterial cells, proteins are the most often observed biomarkers. While this approach samples only a small percentage of the total proteins produced in the cells, these profiles have been reported by many groups to be suitable for taxonomic identification, down to at least the strain level. The wide availability of the MALDI-TOF instrumentation and its relative ease of use, coupled with relatively simple sample preparation procedures, have been key features in the rapid advancement of this approach. 

Biomarkers (molecules of clinical significance) are often present in blood plasma, and the goal of many commercial systems under development is to rapidly estimate the concentration of these molecules - either in batches or continuously. Since one can draw (Mily a limited quantity of blood from a patient for analysis, one is compelled to use as small an amount as possible for each analysis. This is especially true if either one wants to assay for multiple biomarkers or one is... 

If the scope of mass spectrometry is limitless, why are the applications of clinical MS almost completely small molecules The answer is that most clinical tests analyze small molecules, biomarkers that are either metabolites or steroids and, hence, mass spectrometers would target those first. Perhaps a more complete answer would also include that methods must be very robust, easily reproduced in different labs, reliable, and subjected to an extensive array of validation tests. Although peptide and protein analysis is increasing rapidly in clinical labs, the MS approaches to these assays is lagging behind somewhat. MS techniques targeting these peptides and proteins exist, but they are primarily in the research stage, with few systems and methods subjected to the clinical rigors of validation. Once the necessary validations occur and methods simplified, it will only be a short time before MS is used routinely in clinical proteomics. 

Cyclodiene pesticides, of which endrin and its oxidized analogs are representative, can also be estimated by receptor-assay technique. Cyclodiene pesticides exert their mode of action by altering central nervous system membrane ion transport. In work reported by Saleh et al. (1993), a labeled amino acid, GABA, that binds to the chloride channel receptor is displaced by endrin (and other similar molecules), and thus serves as an assay for these pesticides. The GABA receptor was shown to be a potentially useful biomarker for organochlorine pesticides such as lindane, toxaphene, endrin, chlordane, and others. The assay involves small quantities of blood (0.1 mL), and requires only that the plasma be separated from the... 

Molecules serving as effective biomarkers in clinical fluids are often low-molecular-mass metabolic end products. These small molecules can often be directly determined in urine however, their determination in plasma or semm often requires some form of protein removal. Creatinine is the most widely used clinical marker to assess renal function. 

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