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Etanidazole
Etanidazole is a nitroimidazole drug that was investigated in clinical trials for its radiosensitizing properties in cancer treatment. Administration of etanidazole results in a decrease of glutathione concentration and inhibits glutathione ''S''-transferase. The result is that tissues become more sensitive to the ionizing radiation. See also * 18F-EF5, a related nitroimidazole * Misonidazole Misonidazole is a radiosensitizer that was investigated in clinical trials. It was used in these trials for radiation therapy to cause normally resistant hypoxic Hypoxia means a lower than normal level of oxygen, and may refer to: Reduced or ins ... References Nitroimidazoles {{antineoplastic-drug-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Misonidazole
Misonidazole is a radiosensitizer that was investigated in clinical trials. It was used in these trials for radiation therapy to cause normally resistant hypoxic Hypoxia means a lower than normal level of oxygen, and may refer to: Reduced or insufficient oxygen * Hypoxia (environmental), abnormally low oxygen content of the specific environment * Hypoxia (medical), abnormally low level of oxygen in the t ... tumor cells to become sensitive to the treatment. See also * Etanidazole References Secondary alcohols Ethers Nitroimidazoles {{antineoplastic-drug-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitroimidazole
5-Nitroimidazole is an organic compound with the formula O2NC3H2N2H. The nitro group at position 5 on the imidazole ring is the most common positional isomer. The term nitroimidazole also refers to a class of antibiotics that share similar chemical structures. Synthesis Imidazole undergoes a nitration reaction with a mixture of nitric acid and sulfuric acid to give 5-nitroimidazole: :C3H3N2H + HNO3 + H2SO4 → O2NC3H2N2H + H2O Nitroimidazole antibiotics From the chemistry perspective, nitroimidazole antibiotics can be classified according to the location of the nitro functional group. Structures with names 4- and 5-nitroimidazole are equivalent from the perspective of drugs since these tautomers readily interconvert. Drugs of the 5-nitro variety include metronidazole, tinidazole, nimorazole, dimetridazole, pretomanid, ornidazole, megazol, and azanidazole. Drugs based on 2-nitromidazoles include benznidazole. Nitroimidazole antibiotics have been used to combat anaerobic ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clinical Trial
Clinical trials are prospective biomedical or behavioral research studies on human participants designed to answer specific questions about biomedical or behavioral interventions, including new treatments (such as novel vaccines, drugs, dietary choices, dietary supplements, and medical devices) and known interventions that warrant further study and comparison. Clinical trials generate data on dosage, safety and efficacy. They are conducted only after they have received health authority/ethics committee approval in the country where approval of the therapy is sought. These authorities are responsible for vetting the risk/benefit ratio of the trial—their approval does not mean the therapy is 'safe' or effective, only that the trial may be conducted. Depending on product type and development stage, investigators initially enroll volunteers or patients into small pilot studies, and subsequently conduct progressively larger scale comparative studies. Clinical trials can vary i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiosensitizing
A radiosensitizer is an agent that makes tumor cells more sensitive to radiation therapy. It is sometimes also known as a radiation sensitizer or radio-enhancer. Mechanism of action Conventional chemotherapeutics are currently being used in conjunction with radiation therapy to increase its effectiveness. Examples include the fluoropyrimidines, gemcitabine and platinum analogs; fluoropyrimidines increase sensitivity by dysregulating S-phase cell cycle checkpoints in tumor cells. Gemcitabine progresses through a similar mechanism, causing cells in the S-phase to disrepair DNA damage caused by the radiation. Platinum analogs such as cisplatin inhibit DNA repair by cross linking strands, and so aggravate the effects of DNA damage induced by radiation. Limitations One of the major limitations of radiotherapy is that the cells of solid tumors become deficient in oxygen. Solid tumors can outgrow their blood supply, causing a low-oxygen state known as hypoxia. Oxygen is a potent rad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glutathione
Glutathione (GSH, ) is an antioxidant in plants, animals, fungi, and some bacteria and archaea. Glutathione is capable of preventing damage to important cellular components caused by sources such as reactive oxygen species, free radicals, peroxides, lipid peroxides, and heavy metals. It is a tripeptide with a gamma peptide linkage between the carboxyl group of the glutamate side chain and cysteine. The carboxyl group of the cysteine residue is attached by normal peptide linkage to glycine. Biosynthesis and occurrence Glutathione biosynthesis involves two adenosine triphosphate-dependent steps: *First, γ-glutamylcysteine is synthesized from L- glutamate and cysteine. This conversion requires the enzyme glutamate–cysteine ligase (GCL, glutamate cysteine synthase). This reaction is the rate-limiting step in glutathione synthesis. *Second, glycine is added to the C-terminal of γ-glutamylcysteine. This condensation is catalyzed by glutathione synthetase. While all animal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme Inhibition
An enzyme inhibitor is a molecule that binds to an enzyme and blocks its activity. Enzymes are proteins that speed up chemical reactions necessary for life, in which substrate molecules are converted into products. An enzyme facilitates a specific chemical reaction by binding the substrate to its active site, a specialized area on the enzyme that accelerates the most difficult step of the reaction. An enzyme inhibitor stops ("inhibits") this process, either by binding to the enzyme's active site (thus preventing the substrate itself from binding) or by binding to another site on the enzyme such that the enzyme's catalysis of the reaction is blocked. Enzyme inhibitors may bind reversibly or irreversibly. Irreversible inhibitors form a chemical bond with the enzyme such that the enzyme is inhibited until the chemical bond is broken. By contrast, reversible inhibitors bind non-covalently and may spontaneously leave the enzyme, allowing the enzyme to resume its function. Rever ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glutathione S-transferase
Glutathione ''S''-transferases (GSTs), previously known as ligandins, are a family of eukaryotic and prokaryotic phase II metabolic isozymes best known for their ability to catalyze the conjugation of the reduced form of glutathione (GSH) to xenobiotic substrates for the purpose of detoxification. The GST family consists of three superfamilies: the cytosolic, mitochondrial, and microsomal—also known as MAPEG—proteins. Members of the GST superfamily are extremely diverse in amino acid sequence, and a large fraction of the sequences deposited in public databases are of unknown function. The Enzyme Function Initiative (EFI) is using GSTs as a model superfamily to identify new GST functions. GSTs can constitute up to 10% of cytosolic protein in some mammalian organs. GSTs catalyse the conjugation of GSH—via a sulfhydryl group—to electrophilic centers on a wide variety of substrates in order to make the compounds more water-soluble. This activity detoxifies endogenous co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Cancer Institute
The National Cancer Institute (NCI) coordinates the United States National Cancer Program and is part of the National Institutes of Health (NIH), which is one of eleven agencies that are part of the U.S. Department of Health and Human Services. The NCI conducts and supports research, training, health information dissemination, and other activities related to the causes, prevention, diagnosis, and treatment of cancer; the supportive care of cancer patients and their families; and cancer survivorship. NCI is the oldest and has the largest budget and research program of the 27 institutes and centers of the NIH ($6.9 billion in 2020). It fulfills the majority of its mission via an extramural program that provides grants for cancer research. Additionally, the National Cancer Institute has intramural research programs in Bethesda, Maryland, and at the Frederick National Laboratory for Cancer Research at Fort Detrick in Frederick, Maryland. The NCI receives more than in funding each ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ionizing Radiation
Ionizing radiation (or ionising radiation), including nuclear radiation, consists of subatomic particles or electromagnetic waves that have sufficient energy to ionize atoms or molecules by detaching electrons from them. Some particles can travel up to 99% of the speed of light, and the electromagnetic waves are on the high-energy portion of the electromagnetic spectrum. Gamma rays, X-rays, and the higher energy ultraviolet part of the electromagnetic spectrum are ionizing radiation, whereas the lower energy ultraviolet, visible light, nearly all types of laser light, infrared, microwaves, and radio waves are non-ionizing radiation. The boundary between ionizing and non-ionizing radiation in the ultraviolet area is not sharply defined, as different molecules and atoms ionize at different energies. The energy of ionizing radiation starts between 10 electronvolts (eV) and 33 eV. Typical ionizing subatomic particles include alpha particles, beta particles, and neutrons. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
18F-EF5
EF5 is a nitroimidazole derivative used in oncology research. Due to its similarity in chemical structure to etanidazole, EF5 binds in cells displaying hypoxia. Non-labeled EF5 has been extensively used in immunohistochemical studies for several years and its hypoxia specificity has been comprehensively evaluated The 18F-radiolabeled derivative of EF5 is being studied for its possibility to be used in positron emission tomography (PET) to detect low levels of oxygen in brain tumors A brain tumor occurs when abnormal cells form within the brain. There are two main types of tumors: malignant tumors and benign (non-cancerous) tumors. These can be further classified as primary tumors, which start within the brain, and secondar ... and several other malignant tumors. This can help show how a tumor will respond to treatment. Targeting tumor hypoxia in cancer treatment aims to overcome radiotherapy resistance of hypoxic tumors. Thus, a major clinical implication for 18F-EF5-PET i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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