|
Thiopurine Methyltransferase
Thiopurine methyltransferase or thiopurine S-methyltransferase (TPMT) is an enzyme that in humans is encoded by the ''TPMT'' gene. A pseudogene for this locus is located on chromosome 18q. Function Thiopurine methyltransferase methylates thiopurine compounds. The methyl donor is S-adenosyl-L-methionine, which is converted to S-adenosyl-L-homocysteine. This enzyme metabolizes thiopurine drugs via S-adenosyl-L-methionine as the S-methyl donor and S-adenosyl-L-homocysteine as a byproduct. Clinical significance Thiopurine drugs such as 6-mercaptopurine are used as chemotherapeutic agents and immunosuppressive drugs. Genetic polymorphisms that affect this enzymatic activity are correlated with variations in sensitivity and toxicity to such drugs within individuals. About 1/300 individual is deficient for the enzyme. Pharmacology TPMT is best known for its role in the metabolism of the thiopurine drugs such as azathioprine, 6-mercaptopurine and 6-thioguanine. TPMT cataly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. Almost all metabolic processes in the cell need enzyme catalysis in order to occur at rates fast enough to sustain life. Metabolic pathways depend upon enzymes to catalyze individual steps. The study of enzymes is called ''enzymology'' and the field of pseudoenzyme analysis recognizes that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their amino acid sequences and unusual 'pseudocatalytic' properties. Enzymes are known to catalyze more than 5,000 biochemical reaction types. Other biocatalysts are catalytic RNA molecules, called ribozymes. Enzymes' specificity comes from their unique three-dimensional structures. Like all catalysts, enzymes increase the reaction ra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Immunosuppressive Drugs
Immunosuppressive drugs, also known as immunosuppressive agents, immunosuppressants and antirejection medications, are medication, drugs that inhibit or prevent activity of the immune system. Classification Immunosuppressive drugs can be classified into five groups: * #Glucocorticoids, glucocorticoids * #Cytostatics, cytostatics * #Antibodies, antibodies * #Drugs acting on immunophilins, drugs acting on immunophilins * #Other drugs, other drugs Glucocorticoids In pharmacologic (supraphysiologic) doses, glucocorticoids, such as prednisone, dexamethasone, and hydrocortisone are used to suppress various allergy, allergic, inflammation, inflammatory, and autoimmune disorders. They are also administered as posttransplantory immunosuppressants to prevent the transplant rejection, acute transplant rejection and graft-versus-host disease. Nevertheless, they do not prevent an infection and also inhibit later tissue reparation, reparative processes. Immunosuppressive mechanism Glucoc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biomarker (medicine)
In medicine, a biomarker is a measurable indicator of the severity or presence of some disease state. More generally a biomarker is anything that can be used as an indicator of a particular disease state or some other physiological state of an organism. According to the WHO, the indicator may be chemical, physical, or biological in nature - and the measurement may be functional, physiological, biochemical, cellular, or molecular. A biomarker can be a substance that is introduced into an organism as a means to examine organ function or other aspects of health. For example, rubidium chloride is used in isotopic labeling to evaluate perfusion of heart muscle. It can also be a substance whose detection indicates a particular disease state, for example, the presence of an antibody may indicate an infection. More specifically, a biomarker indicates a change in expression or state of a protein that correlates with the risk or progression of a disease, or with the susceptibility of the dis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ototoxicity
Ototoxicity is the property of being toxic to the ear (''oto-''), specifically the cochlea or auditory nerve and sometimes the vestibular system, for example, as a side effect of a drug. The effects of ototoxicity can be reversible and temporary, or irreversible and permanent. It has been recognized since the 19th century. There are many well-known ototoxic drugs used in clinical situations, and they are prescribed, despite the risk of hearing disorders, for very serious health conditions. Ototoxic drugs include antibiotics (such as gentamicin, streptomycin, tobramycin), loop diuretics (such as furosemide), and platinum-based chemotherapy agents (such as cisplatin and carboplatin). A number of nonsteroidal anti-inflammatory drugs (NSAIDS) have also been shown to be ototoxic. This can result in sensorineural hearing loss, dysequilibrium, or both. Some environmental and occupational chemicals have also been shown to affect the auditory system and interact with noise. Signs and sym ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cisplatin
Cisplatin is a chemotherapy medication used to treat a number of cancers. These include testicular cancer, ovarian cancer, cervical cancer, breast cancer, bladder cancer, head and neck cancer, esophageal cancer, lung cancer, mesothelioma, brain tumors and neuroblastoma. It is given by injection into a vein. Common side effects include bone marrow suppression, hearing problems, including total irreversible hearing loss, usually restricted to one ear, kidney damage, and vomiting. Other serious side effects include numbness, trouble walking, allergic reactions, electrolyte problems, and heart disease. Use during pregnancy can cause harm to the developing fetus. Cisplatin is in the platinum-based antineoplastic family of medications. It works in part by binding to DNA and inhibiting its replication. Cisplatin was discovered in 1845 and licensed for medical use in 1978 and 1979. It is on the World Health Organization's List of Essential Medicines. Medical use Cisplatin is a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bone Marrow Suppression
Bone marrow suppression also known as myelotoxicity or myelosuppression, is the decrease in production of cells responsible for providing immunity (leukocytes), carrying oxygen (erythrocytes), and/or those responsible for normal blood clotting (thrombocytes). Bone marrow suppression is a serious side effect of chemotherapy and certain drugs affecting the immune system such as azathioprine. The risk is especially high in cytotoxic chemotherapy for leukemia. Nonsteroidal anti-inflammatory drugs (NSAIDs), in some rare instances, may also cause bone marrow suppression. The decrease in blood cell counts does not occur right at the start of chemotherapy because the drugs do not destroy the cells already in the bloodstream (these are not dividing rapidly). Instead, the drugs affect new blood cells that are being made by the bone marrow. When myelosuppression is severe, it is called myeloablation. Many other drugs including common antibiotics may cause bone marrow suppression. Unlike che ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leukopenia
Leukopenia () is a decrease in the number of leukocytes (WBC). Found in the blood, they are the white blood cells, and are the body's primary defense against an infection. Thus the condition of leukopenia places individuals at increased risk of infection. Signs and symptoms Symptoms may include: * skin or mouth ulcers * sore throat * cough * difficulty in breathing * light-headedness * fever * chills * body aches. Leukopenia vs. neutropenia Neutropenia, a subtype of leukopenia, refers to a decrease in the number of circulating neutrophil granulocytes, the most abundant white blood cells. The terms ''leukopenia'' and ''neutropenia'' may occasionally be used interchangeably, as the neutrophil count is the most important indicator of infection risk. Agranulocytosis is an acute form of neutropenia. Causes Medical conditions Low white cell count may be due to acute viral infections, such as a cold or influenza. It has been associated with chemotherapy, radiation therapy, myelofibr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myelosuppression
Bone marrow suppression also known as myelotoxicity or myelosuppression, is the decrease in production of cells responsible for providing immunity (leukocytes), carrying oxygen (erythrocytes), and/or those responsible for normal blood clotting (thrombocytes). Bone marrow suppression is a serious side effect of chemotherapy and certain drugs affecting the immune system such as azathioprine. The risk is especially high in cytotoxic chemotherapy for leukemia. Nonsteroidal anti-inflammatory drugs (NSAIDs), in some rare instances, may also cause bone marrow suppression. The decrease in blood cell counts does not occur right at the start of chemotherapy because the drugs do not destroy the cells already in the bloodstream (these are not dividing rapidly). Instead, the drugs affect new blood cells that are being made by the bone marrow. When myelosuppression is severe, it is called myeloablation. Many other drugs including common antibiotics may cause bone marrow suppression. Unlike che ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
6-thioguanine
Tioguanine, also known as thioguanine or 6-thioguanine (6-TG) is a medication used to treat acute myeloid leukemia (AML), acute lymphocytic leukemia (ALL), and chronic myeloid leukemia (CML). Long-term use is not recommended. It is given by mouth. Common side effects include bone marrow suppression, liver problems and inflammation of the mouth. It is recommended that liver enzymes be checked weekly when on the medication. People with a genetic deficiency in thiopurine S-methyltransferase are at higher risk of side effects. Avoiding pregnancy when on the medication is recommended for both males and females. Tioguanine is in the antimetabolite family of medications. It is a purine analogue of guanine and works by disrupting DNA and RNA. Tioguanine was developed between 1949 and 1951. It is on the World Health Organization's List of Essential Medicines. Medical uses *Acute leukemias in both adults and children * Chronic myelogenous leukemia * Inflammatory bowel disease, especia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Azathioprine
Azathioprine (AZA), sold under the brand name Imuran, among others, is an immunosuppressive medication. It is used in rheumatoid arthritis, granulomatosis with polyangiitis, Crohn's disease, ulcerative colitis, and systemic lupus erythematosus, and in kidney transplants to prevent rejection. It is listed by the International Agency for Research on Cancer as a group 1 carcinogen (carcinogenic to humans). It is taken by mouth or injected into a vein. Common side effects include bone-marrow suppression and vomiting. Bone-marrow suppression is especially common in people with a genetic deficiency of the enzyme thiopurine S-methyltransferase. Other serious risk factors include an increased risk of certain cancers. Use during pregnancy may result in harm to the baby. Azathioprine is in the purine analogue and antimetabolite family of medications. It works via 6-thioguanine to disrupt the making of RNA and DNA by cells. Azathioprine was first made in 1957. It is on the World Hea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemotherapy
Chemotherapy (often abbreviated to chemo and sometimes CTX or CTx) is a type of cancer treatment that uses one or more anti-cancer drugs (chemotherapeutic agents or alkylating agents) as part of a standardized chemotherapy regimen. Chemotherapy may be given with a curative intent (which almost always involves combinations of drugs) or it may aim to prolong life or to reduce symptoms ( palliative chemotherapy). Chemotherapy is one of the major categories of the medical discipline specifically devoted to pharmacotherapy for cancer, which is called ''medical oncology''. The term ''chemotherapy'' has come to connote non-specific usage of intracellular poisons to inhibit mitosis (cell division) or induce DNA damage, which is why inhibition of DNA repair can augment chemotherapy. The connotation of the word chemotherapy excludes more selective agents that block extracellular signals (signal transduction). The development of therapies with specific molecular or genetic targets, wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a basic unit of heredity and the molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protein-coding genes and noncoding genes. During gene expression, the DNA is first copied into RNA. The RNA can be directly functional or be the intermediate template for a protein that performs a function. The transmission of genes to an organism's offspring is the basis of the inheritance of phenotypic traits. These genes make up different DNA sequences called genotypes. Genotypes along with environmental and developmental factors determine what the phenotypes will be. Most biological traits are under the influence of polygenes (many different genes) as well as gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
