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Toxicophore
A toxicophore is a chemical structure or a portion of a structure (e.g., a functional group) that is related to the toxic properties of a chemical. Toxicophores can act directly (e.g., dioxins and dioxin-like compounds, dioxins) or can require Drug metabolism, metabolic activation (e.g., tobacco-specific nitrosamines). Most toxic substances exert their toxicity through some interaction (e.g., covalent bonding, oxidation) with cellular macromolecules like proteins or DNA. This interaction leads to changes in the normal cellular biochemistry and physiology and downstream toxic effects. Occasionally, the toxicophore requires Biological activity, bioactivation, mediated by enzymes, to produce a more reactive metabolite that is more toxic. For example, tobacco-specific nitrosamines are activated by cytochrome P450 enzymes to form a more reactive substance that can covalently bind to DNA, causing mutations that, if not DNA repair, repaired, can lead to cancer. Generally, different chemical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toxicity
Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell ( cytotoxicity) or an organ such as the liver (hepatotoxicity). By extension, the word may be metaphorically used to describe toxic effects on larger and more complex groups, such as the family unit or society at large. Sometimes the word is more or less synonymous with poisoning in everyday usage. A central concept of toxicology is that the effects of a toxicant are dose-dependent; even water can lead to water intoxication when taken in too high a dose, whereas for even a very toxic substance such as snake venom there is a dose below which there is no detectable toxic effect. Toxicity is species-specific, making cross-species analysis problematic. Newer paradigms and metrics are evolving to bypas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical
A chemical substance is a form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent elements by physical separation methods, i.e., without breaking chemical bonds. Chemical substances can be simple substances (substances consisting of a single chemical element), chemical compounds, or alloys. Chemical substances are often called 'pure' to set them apart from mixtures. A common example of a chemical substance is pure water; it has the same properties and the same ratio of hydrogen to oxygen whether it is isolated from a river or made in a laboratory. Other chemical substances commonly encountered in pure form are diamond (carbon), gold, table salt (sodium chloride) and refined sugar (sucrose). However, in practice, no substance is entirely pure, and chemical purity is specified according to the intended use of the chemical. Chemical substances exist as solids, liquids, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytochrome P450
Cytochromes P450 (CYPs) are a Protein superfamily, superfamily of enzymes containing heme as a cofactor (biochemistry), cofactor that functions as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and xenobiotics, and are important for the clearance (pharmacology), clearance of various compounds, as well as for hormone synthesis and breakdown. In 1963, Ronald W. Estabrook, Estabrook, David Y. Cooper, Cooper, and Otto Rosenthal, Rosenthal described the role of CYP as a catalyst in steroid hormone synthesis and drug metabolism. In plants, these proteins are important for the biosynthesis of secondary metabolite, defensive compounds, fatty acids, and hormones. CYP enzymes have been identified in all kingdom (biology), kingdoms of life: animals, plants, fungus, fungi, protists, bacteria, and archaea, as well as in viruses. However, they are not omnipresent; for example, they have not been found in ''Escherichia coli''. , more than 300,000 distinct CYP proteins ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Predictive Modeling
Predictive modelling uses statistics to predict outcomes. Most often the event one wants to predict is in the future, but predictive modelling can be applied to any type of unknown event, regardless of when it occurred. For example, predictive models are often used to detect crimes and identify suspects, after the crime has taken place. In many cases the model is chosen on the basis of detection theory to try to guess the probability of an outcome given a set amount of input data, for example given an email determining how likely that it is spam. Models can use one or more classifiers in trying to determine the probability of a set of data belonging to another set. For example, a model might be used to determine whether an email is spam or "ham" (non-spam). Depending on definitional boundaries, predictive modelling is synonymous with, or largely overlapping with, the field of machine learning, as it is more commonly referred to in academic or research and development contexts. W ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Environmental Protection Agency
The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it began operation on December 2, 1970, after Nixon signed an executive order. The order establishing the EPA was ratified by committee hearings in the House and Senate. The agency is led by its administrator, who is appointed by the president and approved by the Senate. The current administrator is Michael S. Regan. The EPA is not a Cabinet department, but the administrator is normally given cabinet rank. The EPA has its headquarters in Washington, D.C., regional offices for each of the agency's ten regions and 27 laboratories. The agency conducts environmental assessment, research, and education. It has the responsibility of maintaining and enforcing national standards under a variety of environmental laws, in consultation with state, tr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemoinformatics
Cheminformatics (also known as chemoinformatics) refers to use of physical chemistry theory with computer and information science techniques—so called "''in silico''" techniques—in application to a range of descriptive and prescriptive problems in the field of chemistry, including in its applications to biology and related molecular fields. Such '' in silico'' techniques are used, for example, by pharmaceutical companies and in academic settings to aid and inform the process of drug discovery, for instance in the design of well-defined combinatorial libraries of synthetic compounds, or to assist in structure-based drug design. The methods can also be used in chemical and allied industries, and such fields as environmental science and pharmacology, where chemical processes are involved or studied. History Cheminformatics has been an active field in various guises since the 1970s and earlier, with activity in academic departments and commercial pharmaceutical research a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
A Priori And A Posteriori
("from the earlier") and ("from the later") are Latin phrases used in philosophy to distinguish types of knowledge, justification, or argument by their reliance on empirical evidence or experience. knowledge is independent from current experience (e.g., as part of a new study). Examples include mathematics,Some associationist philosophers have contended that mathematics comes from experience and is not a form of any a priori knowledge () tautologies, and deduction from pure reason.Galen Strawson has stated that an argument is one in which "you can see that it is true just lying on your couch. You don't have to get up off your couch and go outside and examine the way things are in the physical world. You don't have to do any science." () knowledge depends on empirical evidence. Examples include most fields of science and aspects of personal knowledge. The terms originate from the analytic methods found in ''Organon'', a collection of works by Aristotle. Prior analytic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
In Silico
In biology and other experimental sciences, an ''in silico'' experiment is one performed on computer or via computer simulation. The phrase is pseudo-Latin for 'in silicon' (correct la, in silicio), referring to silicon in computer chips. It was coined in 1987 as an allusion to the Latin phrases , , and , which are commonly used in biology (especially systems biology). The latter phrases refer, respectively, to experiments done in living organisms, outside living organisms, and where they are found in nature. History The earliest known use of the phrase was by Christopher Langton to describe artificial life, in the announcement of a workshop on that subject at the Center for Nonlinear Studies at the Los Alamos National Laboratory in 1987. The expression ''in silico'' was first used to characterize biological experiments carried out entirely in a computer in 1989, in the workshop "Cellular Automata: Theory and Applications" in Los Alamos, New Mexico, by Pedro Miramontes, a ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moiety (chemistry)
In organic chemistry, a moiety ( ) is a part of a molecule that is given a name because it is identified as a part of other molecules as well. Typically, the term is used to describe the larger and characteristic parts of organic molecules, and it should not be used to describe or name smaller functional groups of atoms that chemically react in similar ways in most molecules that contain them. Occasionally, a moiety may contain smaller moieties and functional groups. A moiety that acts as a branch extending from the backbone of a hydrocarbon molecule is called a substituent or side chain, which typically can be removed from the molecule and substituted with others. Active moiety In pharmacology, an active moiety is the part of a molecule or ion – excluding appended inactive portions – that is responsible for the physiological or pharmacological action of a drug substance. Inactive appended portions of the drug substance may include either the alcohol or acid moiety of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Structural Biology
Structural biology is a field that is many centuries old which, and as defined by the Journal of Structural Biology, deals with structural analysis of living material (formed, composed of, and/or maintained and refined by living cells) at every level of organization. Early structural biologists throughout the 19th and early 20th centuries were primarily only able to study structures to the limit of the naked eye's visual acuity and through magnifying glasses and light microscopes. In the 20th century, a variety of experimental techniques were developed to examine the 3D structures of biological molecules. The most prominent techniques are X-ray crystallography, nuclear magnetic resonance, and electron microscopy. Through the discovery of X-rays and its applications to protein crystals, structural biology was revolutionized, as now scientists could obtain the three-dimensional structures of biological molecules in atomic detail. Likewise, NMR spectroscopy allowed information about p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Medicinal Chemistry
Medicinal or pharmaceutical chemistry is a scientific discipline at the intersection of chemistry and pharmacy involved with designing and developing pharmaceutical drugs. Medicinal chemistry involves the identification, synthesis and development of new chemical entities suitable for therapeutic use. It also includes the study of existing drugs, their biological properties, and their quantitative structure-activity relationships (QSAR). Medicinal chemistry is a highly interdisciplinary science combining organic chemistry with biochemistry, computational chemistry, pharmacology, molecular biology, statistics, and physical chemistry. Compounds used as medicines are most often organic compounds, which are often divided into the broad classes of small organic molecules (e.g., atorvastatin, fluticasone, clopidogrel) and "biologics" (infliximab, erythropoietin, insulin glargine), the latter of which are most often medicinal preparations of proteins (natural and recombinant ant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DNA Repair
DNA repair is a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. In human cells, both normal metabolic activities and environmental factors such as radiation can cause DNA damage, resulting in tens of thousands of individual molecular lesions per cell per day. Many of these lesions cause structural damage to the DNA molecule and can alter or eliminate the cell's ability to transcribe the gene that the affected DNA encodes. Other lesions induce potentially harmful mutations in the cell's genome, which affect the survival of its daughter cells after it undergoes mitosis. As a consequence, the DNA repair process is constantly active as it responds to damage in the DNA structure. When normal repair processes fail, and when cellular apoptosis does not occur, irreparable DNA damage may occur, including double-strand breaks and DNA crosslinkages (interstrand crosslinks or ICLs). This can eventually lead to malignant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
