Biologic markers biomarkers

Extensive research is currently underway to use biological markers (biomarkers) in exposure and risk assessment. Biomarkers include the reaction products of chemicals or their metabolic products with biological macromolecules, especially with DNA. They also involve indicators of effect, such as chromosomal damage, and indicators of individual genetic susceptibility. 

Per definitions provided by the U.S. National Institutes of Health expert working group, a biological marker (biomarker) is a characteristic that is objectively measured and evaluated as an indicator of normal biological processes, pathogenic processes, or pharmacological responses to a... 

Biological marker (biomarker) Indicators of changes or events in human biological systems. Biological markers of exposnre refer to cellular, biochemical or molecular measures that are obtained from biological media such as human tissues, cells or fluids and are indicative of exposnre to environmental contaminants (NRC, 1991). 

Biological marker (biomarker) molecules are compounds that have distinctive biotic sources and that retain their identity after burial in sediments, even after partial alteration. Most biomarkers are lipids, which are hydrocarbons and hydrocarbon-like molecules. Because of their low susceptibility to microbial degradation compared to other types of organic matter, saturated hydrocarbons — those having only carbon-carbon single bonds — can record many aspects of the depositional history of organic matter sources in lake sediments. A number of detailed reviews of the biomarker contents of lake sediments exist (e.g., Barnes Barnes, 1978 Cranwell, 1982 Johns, 1986 Muller, 1987 Meyers Ishiwatari, 1993). 

A range of biomarkers (biological markers) have been developed for the detection of microorganisms using both their genetic (DNA and RNA) and biochemical components. Most methods have originated from studies on pure isolates and have been adapted to identify and quantify either the total or a sub.set of the microbial biomass in a sample. In these methods,. specific taxonomic or pheno-... 

No data were located concerning methods to measure biological markers of hexachlorobutadiene effects. Research into biomarkers of effect would be most useful if performed in conjunction with development of sensitive, specific, and reliable methods for measuring the biomarker(s) of effect. 

Hulka, B.S. 1991. Epidemiological studies using biological markers Issues for epidemiologists. Cancer Epidemiol. Biomarkers Prev. 1 (1) 13-19. 

Food fingerprint can be defined as a specific molecular marker diagnostic for a characteristic food/nutritional state or condition. These biological markers also referred as biomarkers are specific indicators that can be objectively measured and evaluated (1). They can be genes, proteins, or metabolites. Biomarker discovery and validation is still a current hot topic for nutrition and food science. Emerging omics technologies provide a good discovery-based approach for... 

Gillan, F.T., and Johns, R.B. (1986) Chemical biomarkers for marine bacteria fatty acids and pigments. In Biological Markers in the Sediment Record (Johns, R.B., ed.), pp. 291-309, Elsevier, New York. 

Aflatoxins, for example, Bj (36) and their biological markers have been determined using ESI (90,91). Aflatoxins B1 B2, G1 G2 were analyzed in food samples by LC/ESI/MS using a 150 x 2-mm C18 column eluted isocratically with acetonitrile-MeOH-10 mM NH4OAc (2 16 15) (90). The positive ESI spectra were dominated by the protonated molecules, which were used for SIM. The method enabled concentrations down to lppb to be detected in various food materials. LC/ESI/MS/MS has been used for the detection of aflatoxin DNA adducts as urinary biomarkers of exposure (91). 

Recent advancements in genomics and proteomics have generated considerable interest in the discovery and validation of biomarkers in mechanism-based drug development [69-71], These advances have been welcomed to reduce the cost, increase success rates, and accelerate timelines in the drug discovery and development process. Herein, a brief overview of the application of biological markers in early discovery, development, toxicological assessments, and efficacy studies in humans is presented. 

A biomarker or biological marker is generally defined as an objectively determined characteristic, which is utilized in the assessment of normal biological processes, pathogenic events, and/or pharmacologic responses to a... 

Requejo A. G. (1992) Quantitative analysis of triterpane and sterane biomarkers methodology and applications in molecular maturity studies. In Biological Markers in Sediments and Petroleum (eds. J. M. Moldowan, P. Albrecht, and R. P. Philp). Prentice Hall, Englewood Cliffs, NJ, pp. 223 -240. 

The use of biological responses (biological markers or biomarkers) in organisms exposed to toxic substances is an approach that may help resolve the problems of causality. Chemicals and physical agents are known to elicit measurable and characteristic biological responses in exposed organisms and such evidence can provide a link between exposure and effect. 

Figure 1 Biomarkers for risk assessment Toward the left are biomarkers of exposure (dosimetry) most of these markers represent values obtained from toxicokinetic studies. Toward the right are biological markers of effect many of these markers are standard signs and symptoms familiar to clinicians. The goal of biomarker research is to obtain more information on the link between biologically effective doses and the early, initial biological changes that can lead to disease such values will come from studies on the mechanism of disease induction.

Ideally, the biomarker of the extent of exposure could also be used to predict the health outcome, but it is rare that sufficient information is available to make such predictions. Quantitation is needed when establishing regulations governing allowable exposures that are protective of health. If it is only important to determine if an exposure has occurred, the presence of a biological marker specific for the chemical of concern may be all that is needed. However, for the purposes of risk assessment - that is, determining the potential for a given exposure to an exogenous substance to cause adverse health effects - quantitation of the amount of biomarker present is required. 

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