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Nitrosomethylurea
''N''-Nitroso-''N''-methylurea (NMU) is a highly reliable carcinogen, mutagen, and teratogen. NMU is an alkylating agent, and exhibits its toxicity by transferring its methyl group to nucleobases in nucleic acids, which can lead to AT:GC transition mutations. NMU is the traditional precursor in the synthesis of diazomethane. It has the potentially advantageous property that the stoichiometric byproducts formed are water, carbon dioxide, and ammonia, which are innocuous or easily removed. However, because it is unstable at temperatures beyond 20 °C and somewhat shock-sensitive, it has become obsolete for this purpose and replaced by other N-nitroso compounds: (''N''-methyl)nitrosamides and nitrosamines. Most chemical supply houses have stopped carrying it. Acute exposure to NMU in humans can result in skin and eye irritation, headache, nausea, and vomiting. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Royal Society Of Chemistry
The Royal Society of Chemistry (RSC) is a learned society and professional association in the United Kingdom with the goal of "advancing the chemistry, chemical sciences". It was formed in 1980 from the amalgamation of the Chemical Society, the Royal Institute of Chemistry, the Faraday Society, and the Society for Analytical Chemistry with a new Royal Charter and the dual role of learned society and professional body. At its inception, the Society had a combined membership of 49,000 in the world. The headquarters of the Society are at Burlington House, Piccadilly, London. It also has offices in Thomas Graham House in Cambridge (named after Thomas Graham (chemist), Thomas Graham, the first president of the Chemical Society) where ''RSC Publishing'' is based. The Society has offices in the United States, on the campuses of The University of Pennsylvania and Drexel University, at the University City Science Center in Philadelphia, Pennsylvania, in both Beijing and Shanghai, People' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Glioma
A glioma is a type of primary tumor that starts in the glial cells of the brain or spinal cord. They are malignant but some are extremely slow to develop. Gliomas comprise about 30% of all brain and central nervous system tumors and 80% of all malignant brain tumors. They are a few common types that include astrocytoma (cancer of astrocytes), glioblastoma (an aggressive form of astrocytoma), oligodendroglioma (cancer of oligodendrocytes), and ependymoma (cancer of ependymal cells). Signs and symptoms Symptoms of gliomas depend on the part of the central nervous system (CNS) that is affected. A brain glioma can cause headaches, vomiting, memory loss, seizures, vision problems, speech difficulties, and cranial nerve disorders as a result of increased intracranial pressure. Cognitive impairments such as vision loss arise in glioma patients when a tumor arises in or around their optic nerve. Spinal cord gliomas can cause pain, weakness, or numbness in the extremities ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Teratogens
Teratology is the study of abnormalities of physiological development in organisms during their life span. It is a sub-discipline in medical genetics which focuses on the classification of congenital abnormalities in Dysmorphic feature, dysmorphology caused by teratogens and also in pharmacology and toxicology. Teratogens are substances that may cause non-heritable birth defects via a toxic effect on an embryo or fetus. Defects include malformations, disruptions, deformations, and dysplasia that may cause stunted growth, delayed mental development, or other congenital disorders that lack structural malformations. These defects can be recognized prior to or at birth as well as later during early childhood. The related term developmental toxicity includes all manifestations of abnormal development that are caused by environmental Insult (medical), insult. The extent to which teratogens will impact an embryo is dependent on several factors, such as how long the embryo has been expo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Nitrosoureas
Nitrosourea is both the name of a molecule, and a class of compounds that include a nitroso (R-NO) group and a urea. Examples Examples include: * Arabinopyranosyl-N-methyl-N-nitrosourea, Arabinopyranosyl-''N''-methyl-''N''-nitrosourea (Aranose) * Carmustine (BCNU, BiCNU) * Chlorozotocin * Ethylnitrosourea (ENU) * Fotemustine * Lomustine (CCNU) * Nimustine * N-Nitroso-N-methylurea, ''N''-Nitroso-''N''-methylurea (NMU) * Ranimustine (MCNU) * Semustine * Streptozocin (Streptozotocin) Nitrosourea compounds are DNA alkylating antineoplastic agent, alkylating agents and are often used in chemotherapy. They are lipophile, lipophilic and thus can cross the blood–brain barrier, making them useful in the treatment of brain tumors such as glioblastoma multiforme. File:Aranose (Haworth).svg, Arabinopyranosyl-N-methyl-N-nitrosourea, Arabinopyranosyl-''N''-methyl-''N''-nitrosourea File:Carmustine.svg, Carmustine File:Chlorozotocin (Haworth).svg, Chlorozotocin File:ENU.svg, Ethylnitrosourea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Nitrosamines
Nitrosamines (or more formally ''N''-nitrosamines) are organic compounds produced by industrial processes. The chemical structure is , where R is usually an alkyl group. Nitrosamines have a nitroso group () that are "probable human carcinogens", bonded to a deprotonated amine. Most nitrosamines are carcinogenic in animals. A 2006 systematic review supports a "positive association between nitrite and nitrosamine intake and gastric cancer, between meat and processed meat intake and gastric cancer and oesophageal cancer, and between preserved fish, vegetable and smoked food intake and gastric cancer, but is not conclusive". Chemistry The organic chemistry of nitrosamines is well developed with regard to their syntheses, their structures, and their reactions. They usually are produced by the reaction of nitrous acid () and secondary amines, although other nitrosyl sources (e.g. , , Alkyl nitrite, RONO) have the same effect: : The nitrous acid usually arises from protonation of a nit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Mutagens
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 w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
IARC Group 2A Carcinogens
IARC group 2A agents are substances and exposure circumstances that have been classified as probable carcinogens by the International Agency for Research on Cancer (IARC). This designation is applied when there is limited evidence of carcinogenicity in humans, as well as ''sufficient evidence'' of carcinogenicity in experimental animals. In some cases, an agent may be classified in this group when there is ''inadequate evidence'' of carcinogenicity in humans along with ''sufficient evidence'' of carcinogenicity in experimental animals and ''strong evidence'' that the carcinogenesis is mediated by a mechanism that also operates in humans. Exceptionally, an agent may be classified in this group solely on the basis of ''limited evidence'' of carcinogenicity in humans. This list is focusing on the hazard linked to the agents. This means that the carcinogenic agents are capable of causing cancer, but this does not take their risk into account, which is the probability of causing a can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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] [Amazon] |
Fetal Resorption
Fetal resorption (also known as fetus resorption) is the disintegration and assimilation of one or more fetuses in the uterus at any stage after the completion of organogenesis, which, in humans, is after the ninth week of gestation. Before organogenesis, the process is called embryo resorption. Resorption is more likely to happen early on in the gestation than later on; a later death of a fetus is likely to result in a miscarriage. In rodents Fetal resorption in rats is common and can be influenced by antioxidants. In canines In 1998, an ultrasound study found that the resorption of one or two conceptuses happen in up to 10% of all dog pregnancies, although many cases of assumed complete resorption of an entire litter Litter consists of waste products that have been discarded incorrectly, without consent, at an unsuitable location. The waste is objects, often man-made, such as aluminum cans, paper cups, food wrappers, cardboard boxes or plastic bottles, but ... are like ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Cleft Palate
A cleft lip contains an opening in the upper lip that may extend into the nose. The opening may be on one side, both sides, or in the middle. A cleft palate occurs when the palate (the roof of the mouth) contains an opening into the nose. The term orofacial cleft refers to either condition or to both occurring together. These disorders can result in feeding problems, speech problems, hearing problems, and frequent ear infections. Less than half the time the condition is associated with other disorders. Cleft lip and palate are the result of tissues of the face not joining properly during development. As such, they are a type of birth defect. The cause is unknown in most cases. Risk factors include smoking during pregnancy, diabetes, obesity, an older mother, and certain medications (such as some used to treat seizures). Cleft lip and cleft palate can often be diagnosed during pregnancy with an ultrasound exam. A cleft lip or palate can be successfully treated with surge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
