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Abstract The term “biomarker” a portmanteau of “biological marker”, refers to a broad subcategory of medical signs that is objective indications of medical state observed from outside the patient which can be measured accurately and reproducibly. National Institutes of Health (NIH) defined a biomarker as a characteristic that is objectively measured and evaluated as an indicator of normal biologic processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention. Any specific molecular alteration of a cell on DNA, RNA, metabolite, or protein level can be referred to as a molecular biomarker. The ideal biomarker should be ethically acceptable, easily sampled dependent on simple chemical analysis, reflect a reversible change, relevant, valid, specific and sensitive. Toxicogenomics defined as the study of the relationship between the structure and activity of the genome and the adverse biological effects of exogenous agents. The term toxicogenomics encompasses transcriptomics, metabonomics, and proteomics. It also defined as studying of cell structure and function in response to toxic compound. Pharmacogentic are studying the effect of genetic variation on the individual in response to drug. Transcriptomics are studying alteration of gene expression as a result of exposure to toxic compound . Metabonomics are studying effect of toxic compound on cellular metabolic effect. Proteomics are studying alteration in level of protein expression in response to toxic compound. Biomarkers have applications in all areas of toxicology, especially in the field of pesticides, metals, and drugs. Measurement of residues of pesticides and their metabolites, and metals in urine, serves as the most accurate and reliable biomarkers of exposure in agriculture, industrial, and occupational safety and health settings. Biomarkers are playing an increasingly important role in drug discovery and development from target identification and validation to clinical application, thereby making the overall process a more rational approach. The advantages of biomarkers are well recognized by the research, medical and pharmaceutical communities. Biomarkers can reduce time factors and costs for Phase I and II clinical trials by replacing clinical endpoints. Biomarkers can also be helpful in redefining the diseases and their therapies by shifting the emphasis of traditional practices of depending on symptoms and morphology to a more rational objective molecular basis. Biomarkers of exposure allow the determination as to whether such organisms have been exposed or not, because the presence of xenobiotics or their metabolites in biological samples from the monitored individual is undoubted proof of exposure. Thus, biomarkers of exposure are suitable for assessing exposure to xenobiotics especially when the organism is not in direct contact with the source of xenobiotics. Biomarkers of effect are very important for in vivo and in vitro toxicological testing as they are able to detect preclinical stages, they offer molecular end-points to measure the response of the exposed system to the assessed xenobiotics . Finally, biomarkers of susceptibility allow us to identify, among all the people in a given population, those individuals that are particularly susceptible to xenobiotics, which also would provide better protection of these individuals. Also computational toxicology is one of a growing research area that is showing advances in molecular biology and chemistry with modeling and computational science in order to increase the predictive power of the field of toxicology. The U.S. Environmental Protection Agency (U.S. EPA) defines computational toxicology as the ‘‘integration of modern computing and information technology with molecular biology to improve agency prioritization of data requirements and risk assessment of chemicals. Nowadays, temporal and spatial changes in selected biological systems and parameters are used to reflect changes in environmental quality and conditions. This biomonitoring approach can range from the assessment of chemical residues in the tissues of living organisms, through to assaying specific biological endpoints. The former, often involving the use of biomarker, can be considered as one form of chemical-based monitoring. The latest technologies, such as microRNAs (miRNAs), have been well recognized as reliable and robust biomarkers for early detection of diseases, birth defects, pathological changes, cancer, and toxicities. Because they are stable in biofluids, such as blood, there is rapidly growing interest in using miRNAs as diagnostic, prognostic, and predictive biomarkers, and the outlook for the clinical application of miRNA discoveries is promising, especially in molecular medicine. The application of miRNAs is still very new. Soon incorporating pharmacological and toxicological targeting of miRNAs into the development of innovative therapeutic strategies will be routine. Still, more innovative biomarkers need to be developed that will be highly sensitive (biotechnology-based techniques), require minimum quantities of sample, and will promise high throughput screening. Conclusion In the field of toxicology, measurement of biomarkers reflects the time-course of an injury and provides information on the molecular mechanisms of toxicity. These biomarkers provide us the confidence of accurate diagnosis, prognosis, and treatment. The biomarkers of early chemical exposure can occur in concert with biomarkers of early disease detection, and that information aids in avoiding further chemical exposure and in strategic development of a novel treatment, including personalized medicine (i.e. treating the patient, and not the disease). In essence, with the utilization of specific biomarkers, an ounce of prevention can be worth a pound of treatment. In the toxicology field, biomarkers should be specific, accurate, sensitive, valid, biologically or clinically relevant, and easy and fast to perform in order to be useful as predictive tools for toxicity testing and surveillance and for improving quantitative estimates of exposure and dose. Therefore, biomarkers are utilized in biomonitoring data that are useful in a variety of applications, from exposure assessment to risk assessment and management. Recommendation There is need for introducing more knowledge about biomarkers in toxicology. More focusing on new biomarkers in toxicology. Introducing more and more technologies and instruments for identifying a lot of biomarkers. Identify more about role of biomarkers for early diagnosis of organ toxicity. There is need for more researches and data about miRNA to be used accurately in toxicology. |