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Genotoxic
Genotoxicity is the property of chemical agents that damage the genetic information within a cell causing mutations, which may lead to cancer. While genotoxicity is often confused with mutagenicity, all mutagens are genotoxic, but some genotoxic substances are not mutagenic. The alteration can have direct or indirect effects on the DNA: the induction of mutations, mistimed event activation, and direct DNA damage leading to mutations. The permanent, heritable changes can affect either somatic cells of the organism or germ cells to be passed on to future generations. Cells prevent expression of the genotoxic mutation by either DNA repair or apoptosis; however, the damage may not always be fixed leading to mutagenesis. To assay for genotoxic molecules, researchers assay for DNA damage in cells exposed to the toxic substrates. This DNA damage can be in the form of single- and double-strand breaks, loss of excision repair, cross-linking, alkali-labile sites, point mutations, and stru ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mutagen
In genetics, a mutagen is a physical or chemical agent that permanently changes genetic material, usually DNA, in an organism and thus increases the frequency of mutations above the natural background level. As many mutations can cause cancer in animals, such mutagens can therefore be carcinogens, although not all necessarily are. All mutagens have characteristic mutational signatures with some chemicals becoming mutagenic through cellular processes. The process of DNA becoming modified is called mutagenesis. Not all mutations are caused by mutagens: so-called "spontaneous mutations" occur due to spontaneous hydrolysis, errors in DNA replication, repair and recombination. Discovery The first mutagens to be identified were carcinogens, substances that were shown to be linked to cancer. Tumors were described more than 2,000 years before the discovery of chromosomes and DNA; in 500 B.C., the Greek physician Hippocrates named tumors resembling a crab ''karkinos'' (from which the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Micronucleus Test
A micronucleus test is a test used in toxicological screening for potential genotoxic compounds. The assay is now recognized as one of the most successful and reliable assays for genotoxic carcinogens, i.e., carcinogens that act by causing genetic damage and is recommended by the OECD guideline for the testing of chemicals. There are two major versions of this test, one ''in vivo'' and the other ''in vitro''. The ''in vivo'' test normally uses mouse bone marrow or mouse peripheral blood. When a bone marrow erythroblast develops into a polychromatic erythrocyte, the main nucleus is extruded; any micronucleus that has been formed may remain behind in the otherwise anucleated cytoplasm. Visualisation of micronuclei is facilitated in these cells because they lack a main nucleus. An increase in the frequency of micronucleated polychromatic erythrocytes in treated animals is an indication of induced chromosome damage. Micronuclei were first used to quantify chromosomal damage by H.J. E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carcinogens
A carcinogen () is any agent that promotes the development of cancer. Carcinogens can include synthetic chemicals, naturally occurring substances, physical agents such as ionizing and non-ionizing radiation, and biologic agents such as viruses and bacteria. Most carcinogens act by creating mutations in DNA that disrupt a cell's normal processes for regulating growth, leading to uncontrolled cellular proliferation. This occurs when the cell's DNA repair processes fail to identify DNA damage allowing the defect to be passed down to daughter cells. The damage accumulates over time. This is typically a multi-step process during which the regulatory mechanisms within the cell are gradually dismantled allowing for unchecked cellular division. The specific mechanisms for carcinogenic activity is unique to each agent and cell type. Carcinogens can be broadly categorized, however, as activation-dependent and activation-independent which relate to the agent's ability to engage direc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrrolizidine Alkaloids
Pyrrolizidine alkaloids (PAs), sometimes referred to as necine bases, are a group of naturally occurring alkaloids based on the structure of pyrrolizidine. Their use dates back centuries and is intertwined with the discovery, understanding, and eventual recognition of their toxicity on humans and animals. History PAs were first discovered in plants in the 19th century, but their toxic effects were not immediately recognized. Instead, many PA-containing plants were traditionally used for medicinal purposes in various cultures around the world. For example, herbs containing PAs were used in traditional Chinese medicine and by Native American tribes for their purported therapeutic properties. It has been estimated that 3% of the world's flowering plants contain pyrrolizidine alkaloids. Honey can contain pyrrolizidine alkaloids, as can grains, milk, offal and eggs. To date (2011), there is no international regulation of PAs in food, unlike those for herbs and medicines. In the ear ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromium
Chromium is a chemical element; it has Symbol (chemistry), symbol Cr and atomic number 24. It is the first element in Group 6 element, group 6. It is a steely-grey, Luster (mineralogy), lustrous, hard, and brittle transition metal. Chromium is valued for its high corrosion resistance and hardness. A major development in steel production was the discovery that steel could be made highly resistant to corrosion and discoloration by adding metallic chromium to form stainless steel. Stainless steel and chrome plating (electroplating with chromium) together comprise 85% of the commercial use. Chromium is also greatly valued as a metal that is able to be highly polishing, polished while resisting tarnishing. Polished chromium reflects almost 70% of the visible spectrum, and almost 90% of infrared, infrared light. The name of the element is derived from the Ancient Greek, Greek word χρῶμα, ''chrōma'', meaning color, because many chromium compounds are intensely colored. Indust ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ames Test
The Ames test is a widely employed method that uses bacteria to test whether a given chemical can cause mutations in the DNA of the test organism. More formally, it is a bioassay, biological assay to assess the mutagenic potential of chemical compounds. A positive test indicates that the chemical is mutagenic and therefore may act as a carcinogen, because cancer is often linked to mutation. The test serves as a quick and convenient assay to estimate the carcinogenic potential of a compound because standard carcinogen assays on mice and rats are time-consuming (taking two to three years to complete) and expensive. However, false-positives and false-negatives are known. The procedure was described in a series of papers in the early 1970s by Bruce Ames and his group at the University of California, Berkeley. General procedure The Ames test uses several strains of the bacterium ''Salmonella typhimurium'' that carry mutations in genes involved in histidine synthesis. These strains a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
In Vitro
''In vitro'' (meaning ''in glass'', or ''in the glass'') Research, studies are performed with Cell (biology), cells or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in biology and its subdisciplines are traditionally done in labware such as test tubes, flasks, Petri dishes, and microtiter plates. Studies conducted using components of an organism that have been isolated from their usual biological surroundings permit a more detailed or more convenient analysis than can be done with whole organisms; however, results obtained from ''in vitro'' experiments may not fully or accurately predict the effects on a whole organism. In contrast to ''in vitro'' experiments, ''in vivo'' studies are those conducted in living organisms, including humans, known as clinical trials, and whole plants. Definition ''In vitro'' (Latin language, Latin for "in glass"; often not italicized in English usage) studies are conducted ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comfrey
''Symphytum'' is a genus of flowering plants in the borage family, Boraginaceae, known by the common name comfrey (pronounced , from the Latin confervere to 'heal' or literally to 'boil together', referring to uses in ancient traditional medicine). ''Symphytum'' is native to northern temperate regions of Asia and North America, with a wide introduced distribution on both continents. There are 59 recognized species. Some species and Hybrid plant, hybrids, particularly ''Symphytum officinale, S. officinale'', ''Symphytum grandiflorum'', and Symphytum × uplandicum, ''S.'' × ''uplandicum'', are used in gardening and herbal medicine. Species in the genus ''Symphytum'' are different from ''Andersonglossum virginianum'', known as wild comfrey, which is another member of the borage family. Species 27 species are accepted. *''Symphytum aintabicum'' *''Symphytum anatolicum'' *''Symphytum asperum'' – prickly comfrey, rough comfrey *''Symphytum × bicknellii'' *''Symphytum bornmuell ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clastogen
A clastogen is a mutagenic agent that disturbs normal DNA related processes or directly causes DNA strand breakages, thus causing the deletion, insertion, or rearrangement of entire chromosome sections. These processes are a form of mutagenesis which if left unrepaired, or improperly repaired, can lead to cancer. Known clastogens include acridine yellow, benzene, ethylene oxide, arsenic, phosphine, mimosine, actinomycin D, camptothecin, methotrexate, methyl acrylate, resorcinol and 5-fluorodeoxyuridine. Additionally, 1,2-dimethylhydrazine is a known colon carcinogen and shows signs of possessing clastogenic activity. There are many clastogens not listed here and research is ongoing to discover new clastogens. Some known clastogens only exhibit clastogenic activity in certain cell types, such as caffeine which exhibits clastogenic activity in plant cells. Researchers are interested in clastogens for researching cancer, as well as for other human health concerns such as the i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carcinogenesis
Carcinogenesis, also called oncogenesis or tumorigenesis, is the formation of a cancer, whereby normal cell (biology), cells are malignant transformation, transformed into cancer cells. The process is characterized by changes at the cellular, Genetics, genetic, and Epigenetics, epigenetic levels and abnormal cell division. Cell division is a physiological process that occurs in almost all Tissue (biology), tissues and under a variety of circumstances. Normally, the balance between proliferation and programmed cell death, in the form of apoptosis, is maintained to ensure the integrity of tissues and Organ (anatomy), organs. According to the prevailing accepted theory of carcinogenesis, the somatic mutation theory, mutations in DNA and Epigenetics, epimutations that lead to cancer disrupt these orderly processes by interfering with the programming regulating the processes, upsetting the normal balance between proliferation and cell death. This results in uncontrolled cell division ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromosome Abnormality
A chromosomal abnormality, chromosomal anomaly, chromosomal aberration, chromosomal mutation, or chromosomal disorder is a missing, extra, or irregular portion of chromosomal DNA. These can occur in the form of numerical abnormalities, where there is an atypical number of chromosomes, or as structural abnormalities, where one or more individual chromosomes are altered. Chromosome mutation was formerly used in a strict sense to mean a change in a chromosomal segment, involving more than one gene. Chromosome anomalies usually occur when there is an error in cell division following meiosis or mitosis. Chromosome abnormalities may be detected or confirmed by comparing an individual's karyotype, or full set of chromosomes, to a typical karyotype for the species via genetic testing. Sometimes chromosomal abnormalities arise in the early stages of an embryo, sperm, or infant. They can be caused by various environmental factors. The implications of chromosomal abnormalities depend on the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
