Biomarkers
Biomarkers are accurately quantifiable indicators that are capable of reflecting normal biological processes, pathogenic processes, incidence or outcome of a disease, pharmacologic responses to a therapeutic intervention, or the adverse effects of a desir
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Biomarkers
Biomarkers are accurately quantifiable indicators that are capable of reflecting normal biological processes, pathogenic processes, incidence or outcome of a disease, pharmacologic responses to a therapeutic intervention, or the adverse effects of a desired new drug. Thus, the biomarkers may be broadly classified into four types: • Diagnostic biomarkers (which reveal the abnormality) • Prognostic biomarkers (which predict the course and/or severity of the disease) • Pharmacodynamic biomarkers (which monitor whether a therapy will work or is working as this marker is altered during the therapeutic recovery) • Toxicity biomarkers (which monitor the toxic effect elicited in the body due to the disease or the drug itself). A single parameter may either be an all-type biomarker or a single-type biomarker. The indicators may be any one of the following: • • • • • •
A specific gene variant Patterns of gene expression Levels of a particular protein in body fluids Concentration of a compound Activity of an enzyme in the body fluid or in the tissue Concentration of a metabolic product.
Biomarkers play a vital task in improving the drug development process as well as in the larger biomedical research enterprise. The U.S. Food and Drug Administration (FDA) is promoting biomarker values in basic and clinical research. Thus, in nanomedicine, there is a need for the evaluation of the diagnostic and therapeutic potential of nanoparticles or the toxic potential of nanotechnologybased drugs during the drug development process. This would help in identifying the therapeutic properties of the test compound, assessing risk, and understanding © The Author(s) 2017 Devasena T, Therapeutic and Diagnostic Nanomaterials, Nanotheranostics, DOI 10.1007/978-981-10-0923-5_3
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Table 3.1 Different types of diagnostic markers Marker type
Detectable parameters
Example
Disease/diseased condition
Biochemical
Oxidative damage markers Antioxidant markers Cytokines
TBARS
Cancer/toxicity
Reduced glutathione, catalase Interleukins
Nephritis
Cell viability marker DNA damage
Formazon
Fibrosis, granuloma
Pulmonary fibrosis
Genetical Histopathological
DNA fragmentation
Pulmonary disorder/inflammation Cell death/cytotoxicity Cardiovascular disease/toxicity Lung inflammation, hepatitis
the mode of action of the nanoparticles (Strimbu and Tavel 2010). Generally, there are three major types of diagnostic marker details of which are summarized in Table 3.1: • Biochemical markers • Genetic markers • Histopathological markers.
3.1
Biochemical Markers
Biochemical parameters are biological or biochemical constituents that are detectable in tissue homogenates, or membrane isolates in body fluids such as cerebrospinal fluid, and urine samples. For testing a drug inclusive of nanomedicines, in vitro markers can be identified before proceeding to in vivo experiments. Biochemical changes associated with most of the diseased states and environmental pollutioninduced abnormalities are hematological changes, oxidative stress,
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