|
Methaneseleninic Acid
Methaneseleninic acid (methylseleninic acid or MSA) is an organoselenium compound, a seleninic acid with the chemical formula . Its structure is . Preparation Methaneseleninic acid is conveniently synthesized through oxidation of commercially available dimethyl diselenide by 3% hydrogen peroxide. : Seleninic acids can be prepared by oxidation of selenoesters with one equivalent of dimethyldioxirane (DMDO). Use of excess DMDO affords little studied selenonic acids (). : : Selenenic acids, formed during the ''syn''-elimination of selenoxides, undergo spontaneous disproportionation into the corresponding seleninic acids and diselenides: : Structure, bonding, properties Methaneseleninic acid, from decomposition of ''Se''-methylselenocysteine ''Se''-oxide but also available commercially, has been characterized by X-ray crystallography. The configuration about the selenium atom is pyramidal, with Se-C = 1.925(8) Å, Se-O = 1.672(7) Å, Se-OH = 1.756(7) Å, the angle OSeO = 103.0(3) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organoselenium Compound
Organoselenium compounds (or seleno-organic) are chemical compounds containing carbon-to-selenium chemical bonds. Organoselenium chemistry is the corresponding science exploring their properties and reactivity. Selenium belongs with oxygen and sulfur to the group 16 elements or chalcogens, and similarities in chemistry are to be expected. Organoselenium compounds are found at trace levels in ambient waters, soils and sediments. Selenium can exist with oxidation state −2, +2, +4, +6. Se(II) is the dominant form in organoselenium chemistry. Down the group 16 column, the bond strength becomes increasingly weaker (234 kJ/ mol for the C−Se bond and 272 kJ/mol for the C−S bond) and the bond lengths longer (C−Se 198 pm, C−S 181 pm and C−O 141 pm). Selenium compounds are more nucleophilic than the corresponding sulfur compounds and also more acidic. The p''K''a values of XH2 are 16 for oxygen, 7 for sulfur and 3.8 for selenium. In contrast to sulfoxides, the corresponding sel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Estrogen Receptor
Estrogen receptors (ERs) are a group of proteins found inside cells. They are receptors that are activated by the hormone estrogen ( 17β-estradiol). Two classes of ER exist: nuclear estrogen receptors (ERα and ERβ), which are members of the nuclear receptor family of intracellular receptors, and membrane estrogen receptors (mERs) (GPER (GPR30), ER-X, and Gq-mER), which are mostly G protein-coupled receptors. This article refers to the former (ER). Once activated by estrogen, the ER is able to translocate into the nucleus and bind to DNA to regulate the activity of different genes (i.e. it is a DNA-binding transcription factor). However, it also has additional functions independent of DNA binding. As hormone receptors for sex steroids (steroid hormone receptors), ERs, androgen receptors (ARs), and progesterone receptors (PRs) are important in sexual maturation and gestation. Proteomics There are two different forms of the estrogen receptor, usually referred to as α a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organoselenium Compounds
Organoselenium compounds (or seleno-organic) are chemical compounds containing carbon-to-selenium chemical bonds. Organoselenium chemistry is the corresponding science exploring their properties and reactivity. Selenium belongs with oxygen and sulfur to the group 16 elements or chalcogens, and similarities in chemistry are to be expected. Organoselenium compounds are found at trace levels in ambient waters, soils and sediments. Selenium can exist with oxidation state −2, +2, +4, +6. Se(II) is the dominant form in organoselenium chemistry. Down the group 16 column, the bond strength becomes increasingly weaker (234 kilojoule, kJ/mole (unit), mol for the C−Se bond and 272 kJ/mol for the C−S bond) and the bond lengths longer (C−Se 198 pm, C−S 181 pm and C−O 141 pm). Selenium compounds are more nucleophilic than the corresponding sulfur compounds and also more acidic. The pKa, p''K''a values of XH2 are 16 for oxygen, 7 for sulfur and 3.8 for selenium. In contrast to sulfoxi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thioredoxin Reductase
Thioredoxin reductases (TR, TrxR) () are enzymes that reduce thioredoxin (Trx). Two classes of thioredoxin reductase have been identified: one class in bacteria and some eukaryotes and one in animals. In bacteria TrxR also catalyzes the reduction of glutaredoxin like proteins known as NrdH. Both classes are flavoproteins which function as homodimers. Each monomer contains a FAD prosthetic group, a NADPH binding domain, and an active site containing a redox-active disulfide bond. Cellular role Thioredoxin reductases are enzymes that catalyze the reduction of thioredoxin and hence they are a central component in the thioredoxin system. Together with thioredoxin (Trx) and NADPH this system's most general description is as a system for reducing disulfide bonds in cells. Electrons are taken from NADPH via TrxR and are transferred to the active site of Trx, which goes on to reduce protein disulfides or other substrates. The Trx system exists in all living cells and has an evolutiona ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superoxide
In chemistry, a superoxide is a compound that contains the superoxide ion, which has the chemical formula . The systematic name of the anion is dioxide(1−). The reactive oxygen ion superoxide is particularly important as the product of the one-electron reduction of dioxygen , which occurs widely in nature. Molecular oxygen (dioxygen) is a diradical containing two unpaired electrons, and superoxide results from the addition of an electron which fills one of the two degenerate molecular orbitals, leaving a charged ionic species with a single unpaired electron and a net negative charge of −1. Both dioxygen and the superoxide anion are free radicals that exhibit paramagnetism. Superoxide was historically also known as "hyperoxide". Salts Superoxide forms salts with alkali metals and alkaline earth metals. The salts caesium superoxide (), rubidium superoxide (), potassium superoxide (), and sodium superoxide () are prepared by the reaction of with the respective alkali me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methaneselenol
Methaneselenol is the organoselenium compound with the formula CH3SeH. It is the simplest selenol. A colorless gas, it is notorious for its foul odor. It is prepared by reaction of methyl lithium or a methyl Grignard reagent with selenium followed by protonation of the product The compound is a metabolite. According to IR spectroscopy, νSe-H = 2342 cm−1. For the other homologues, νE-H = 1995 (E = Te), 2606 (E = S), and 3710 cm−1 (E = O) for methanetellurol, methanethiol, and methanol Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical and the simplest aliphatic alcohol, with the formula C H3 O H (a methyl group linked to a hydroxyl group, often abbreviated as MeOH). It is a ....{{cite journal , doi=10.1080/00945717708069709, title=The Synthesis and the Raman and Infrared Spectra of Methanetellurol, year=1977, last1=Hamada, first1=K., last2=Morishita, first2=H., journal=Synthesis and Reactivity in Inorga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lewis Lung Carcinoma
Lewis lung carcinoma is a tumor that spontaneously developed as an epidermoid carcinoma in the lung of a C57BL mouse. It was discovered in 1951 by Dr. Margaret Lewis of the Wistar Institute and became one of the first transplantable tumors. Models Syngeneic According to a 2015 review article, Lewis lung carcinoma is the only reproducible syngeneic lung cancer model, meaning that it is the only reproducible lung cancer model that utilizes a transplant that is immunologically compatible. Syngeneic models have proven to be useful in predicting clinical benefit of therapy in preclinical experiments. However, there has been criticism directed towards syngeneic model usage when attempting to translate therapies from another species to humans. For example, cancer therapies that exhibited promising results in mouse models can and have failed in clinical trials due to physiological differences in the activity of the targeted gene product. The activity of the mouse product did not transla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metastatic Breast Cancer
Metastatic breast cancer, also referred to as metastases, advanced breast cancer, secondary tumors, secondaries or stage IV breast cancer, is a stage of breast cancer where the breast cancer cells have spread to distant sites beyond the axillary lymph nodes. There is no cure for metastatic breast cancer; there is no stage after IV. Metastases can occur several years after the primary breast cancer, although it is sometimes diagnosed at the same time as the primary breast cancer or, rarely, before the primary breast cancer has been diagnosed. Metastatic breast cancer cells frequently differ from the preceding primary breast cancer in properties such as receptor status. The cells have often developed resistance to several lines of previous treatment and have acquired special properties that permit them to metastasize to distant sites. Metastatic breast cancer can be treated, sometimes for many years, but it cannot be cured. Distant metastases are the cause of about 90% of deaths du ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nude Mouse
A nude mouse is a laboratory mouse from a strain with a genetic mutation that causes a deteriorated or absent thymus, resulting in an inhibited immune system due to a greatly reduced number of T cells. The phenotype (main outward appearance) of the mouse is a lack of body hair, which gives it the "nude" nickname. The nude mouse is valuable to research because it can receive many different types of tissue and tumor grafts, as it mounts no rejection response. These xenografts are commonly used in research to test new methods of imaging and treating tumors. The genetic basis of the nude mouse mutation is a disruption of the FOXN1 gene. Nomenclature The nomenclature for the nude mouse has changed several times since their discovery. Originally they were described as ''nu'' and this was updated to ''Hfh11nu'' when the mutated gene was identified as a mutation in the HNF-3/forkhead homolog 11 gene. Then in 2000 the gene responsible for the mutation was identified as a member of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ABT-737
ABT-737 is a small molecule drug that inhibits Bcl-2 and Bcl-xL, two members of the Bcl-2 family of evolutionarily-conserved proteins that share Bcl-2 Homology (BH) domains. First developed as a potential cancer chemotherapy, it was subsequently identified as a senolytic (a drug that selectively induces cell death in senescent cells). The Bcl-2 family is most notable for their regulation of apoptosis, a form of programmed cell death, at the mitochondrion; Bcl-2 and Bcl-xL are anti-apoptotic proteins. Because many cancers have mutations in these genes that allow them to survive, scientists began working to develop drugs that would inhibit this pathway in the 1990s. ABT-737 was one of the earliest of a series of drugs developed by Abbott Laboratories (now Abbvie) to target this pathway, based on their resolution of the 3D structure of Bcl-xL and studies using high-field solution nuclear magnetic resonance (NMR) that revealed how the BH domains of these proteins interacted with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bcl-2
Bcl-2 (B-cell lymphoma 2), encoded in humans by the ''BCL2'' gene, is the founding member of the Bcl-2 family of regulator proteins that regulate cell death (apoptosis), by either inhibiting (anti-apoptotic) or inducing (pro-apoptotic) apoptosis. It was the first apoptosis regulator identified in any organism. Bcl-2 derives its name from ''B-cell lymphoma 2'', as it is the second member of a range of proteins initially described in chromosomal translocations involving chromosomes 14 and 18 in follicular lymphomas. Orthologs (such as ''Bcl2'' in mice) have been identified in numerous mammals for which complete genome data are available. Like BCL3, BCL5, BCL6, BCL7A, BCL9, and BCL10, it has clinical significance in lymphoma. Isoforms The two isoforms of Bcl-2, Isoform 1, and Isoform 2, exhibit a similar fold. However, results in the ability of these isoforms to bind to the BAD and BAK proteins, as well as in the structural topology and electrostatic potential of the binding ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apoptosis
Apoptosis (from grc, ἀπόπτωσις, apóptōsis, 'falling off') is a form of programmed cell death that occurs in multicellular organisms. Biochemical events lead to characteristic cell changes (morphology) and death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, DNA fragmentation, and mRNA decay. The average adult human loses between 50 and 70 billion cells each day due to apoptosis. For an average human child between eight and fourteen years old, approximately twenty to thirty billion cells die per day. In contrast to necrosis, which is a form of traumatic cell death that results from acute cellular injury, apoptosis is a highly regulated and controlled process that confers advantages during an organism's life cycle. For example, the separation of fingers and toes in a developing human embryo occurs because cells between the digits undergo apoptosis. Unlike necrosis, apoptosis produces cell fragments called apoptotic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
