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CYP2R1
CYP2R1 is cytochrome P450 2R1, an enzyme which is the principal vitamin D 25-hydroxylase. In humans it is encoded by the ''CYP2R1'' gene located on chromosome 11p15.2. It is expressed in the endoplasmic reticulum in liver, where it performs the first step in the activation of vitamin D by catalyzing the formation of 25-hydroxyvitamin D. Vitamin D 25-hydroxylase activity is also possessed by some other cytochrome P450 enzymes, in particular CYP27A1, which is found in mitochondria. Function CYP2R1 is a member of the cytochrome P450 superfamily of enzymes. The cytochrome P450 proteins are mono-oxygenases which catalyze many reactions involved in drug metabolism and synthesis of cholesterol, steroids and other lipids. CYP2R1 is present in the endoplasmic reticulum of the liver (the microsomal fraction). It has 25-hydroxylase activity, which converts cholecalciferol (vitamin D3) into calcifediol (25-hydroxyvitamin D3, also known as calcidiol), the major circulatory form of the v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cholecalciferol
Cholecalciferol, also known as vitamin D3, colecalciferol or calciol, is a type of vitamin D that is produced by the skin when exposed to UV light, UVB light; it is found in certain foods and can be taken as a dietary supplement. Cholecalciferol is synthesised in the skin following sunlight exposure. It is then converted in the liver to calcifediol (25-hydroxycholecalciferol D), which is further converted in the kidney to calcitriol (1,25-dihydroxycholecalciferol D). One of calcitriol's most important functions is to promote calcium uptake by the intestines. Cholecalciferol is present in food such as fatty fish, beef liver, eggs, and cheese. In some countries, cholecalciferol is also added to products like plants, cow milk, fruit juice, yogurt, and margarine. Cholecalciferol can be taken orally as a dietary supplement to prevent vitamin D deficiency or as a medication to treat associated diseases, including rickets. It is also used in the management of familial hypophosphatem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vitamin D
Vitamin D is a group of structurally related, fat-soluble compounds responsible for increasing intestinal absorption of calcium, magnesium, and phosphate, along with numerous other biological functions. In humans, the most important compounds within this group are vitamin D3 ( cholecalciferol) and vitamin D2 ( ergocalciferol). Unlike the other twelve vitamins, vitamin D is only conditionally essential, as with adequate skin exposure to the ultraviolet B (UVB) radiation component of sunlight there is synthesis of cholecalciferol in the lower layers of the skin's epidermis. For most people, skin synthesis contributes more than diet sources. Vitamin D can also be obtained through diet, food fortification and dietary supplements. In the U.S., cow's milk and plant-based milk substitutes are fortified with vitamin D3, as are many breakfast cereals. Government dietary recommendations typically assume that all of a person's vitamin D is taken by mouth, given the potential for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calcifediol
Calcifediol, also known as calcidiol, 25-hydroxycholecalciferol, or 25-hydroxyvitamin D3 (abbreviated 25(OH)D3), is a form of vitamin D produced in the liver by hydroxylation of vitamin D3 (cholecalciferol) by the enzyme vitamin D 25-hydroxylase. Calcifediol can be further hydroxylated by the enzyme 25(OH)D-1α-hydroxylase, primarily in the kidney, to form calcitriol (1,25-(OH)2D3), which is the active hormonal form of vitamin D. Calcifediol is strongly bound in blood by the vitamin D-binding protein. Measurement of serum calcifediol is the usual test performed to determine a person's vitamin D status, to show vitamin D deficiency or sufficiency. Calcifediol is available as an oral medication in some countries to supplement vitamin D status. Biology Calcifediol is the precursor for calcitriol, the active form of vitamin D. It is synthesized in the liver, by hydroxylation of cholecalciferol (vitamin D3) at the 25-position. This enzymatic 25-hydroxylase reaction is mostly due t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vitamin D Deficiency
Vitamin D deficiency or hypovitaminosis D is a vitamin D level that is below normal. It most commonly occurs in people when they have inadequate exposure to sunlight, particularly sunlight with adequate ultraviolet B rays (UVB). Vitamin D deficiency can also be caused by inadequate nutritional intake of vitamin D; disorders that limit vitamin D absorption; and disorders that impair the conversion of vitamin D to active metabolites, including certain liver, kidney, and hereditary disorders. Deficiency impairs bone mineralization, leading to bone-softening diseases, such as rickets in children. It can also worsen osteomalacia and osteoporosis in adults, increasing the risk of bone fractures. Muscle weakness is also a common symptom of vitamin D deficiency, further increasing the risk of falls and bone fractures in adults. Vitamin D deficiency is associated with the development of schizophrenia. Vitamin D can be synthesized in the skin under exposure to UVB from sunlight. Oily ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rickets
Rickets, scientific nomenclature: rachitis (from Greek , meaning 'in or of the spine'), is a condition that results in weak or soft bones in children and may have either dietary deficiency or genetic causes. Symptoms include bowed legs, stunted growth, bone pain, large forehead, and trouble sleeping. Complications may include bone Deformity, deformities, bone pseudofractures and Bone fracture, fractures, muscle spasms, or an scoliosis, abnormally curved spine. The analogous condition in adults is osteomalacia. The most common cause of rickets is a hypovitaminosis D, vitamin D deficiency, although hereditary genetic forms also exist. This can result from eating a diet without enough vitamin D, dark skin, too little sun exposure, exclusive breastfeeding without vitamin D supplementation, celiac disease, and certain genetic conditions. Other factors may include not enough calcium or phosphorus. The underlying mechanism involves insufficient calcification of the growth plate. Di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ergocalciferol
Ergocalciferol, also known as vitamin D2 and nonspecifically calciferol, is a type of vitamin D found in food. It is used as a dietary supplement to prevent and treat vitamin D deficiency due to poor absorption by the intestines or liver disease. It may also be used for low blood calcium due to hypoparathyroidism. It is taken by mouth or via injection into a muscle. Excessive doses can result in vitamin D toxicity causing increased urine production, high blood pressure, kidney stones, kidney failure, muscle weakness, and constipation. If high doses are taken for a long period of time, tissue calcification may occur. Normal doses are safe in pregnancy. It works by increasing the amount of calcium absorbed by the intestines and reabsorbed by the kidneys. Food in which it is found include some mushrooms. Ergocalciferol was first described in 1936. Ergocalciferol is available as a generic medication and over the counter. In 2022, it was the 38th most commonly prescribe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme
An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different molecules known as product (chemistry), products. Almost all metabolism, metabolic processes in the cell (biology), 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, 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 include Ribozyme, catalytic RNA molecules, also called ribozymes. They are sometimes descr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glucocorticoids
Glucocorticoids (or, less commonly, glucocorticosteroids) are a class of corticosteroids, which are a class of steroid hormones. Glucocorticoids are corticosteroids that bind to the glucocorticoid receptor that is present in almost every vertebrate animal cell. The name "glucocorticoid" is a portmanteau of "glucose", "cortex", and "steroid" and is composed from its role in regulation of glucose metabolism, synthesis in the adrenal cortex, and its steroidal structure (see structure below). Glucocorticoids are part of the feedback mechanism in the immune system, which reduces certain aspects of immune function, such as inflammation. They are therefore used in medicine to treat diseases caused by an overactive immune system, such as allergies, asthma, autoimmune diseases, and sepsis. Glucocorticoids have many diverse effects such as pleiotropy, including potentially harmful side effects. They also interfere with some of the abnormal mechanisms in cancer cells, so they are used in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dexamethasone
Dexamethasone is a fluorinated glucocorticoid medication used to treat rheumatic problems, a number of skin diseases, severe allergies, asthma, chronic obstructive pulmonary disease (COPD), croup, brain swelling, eye pain following eye surgery, superior vena cava syndrome (a complication of some forms of cancer), and along with antibiotics in tuberculosis. In adrenocortical insufficiency, it may be used in combination with a mineralocorticoid medication such as fludrocortisone. In preterm labor, it may be used to improve outcomes in the baby. It may be given by mouth, as an injection into a muscle, as an injection into a vein, as a topical cream or ointment for the skin or as a topical ophthalmic solution to the eye. The effects of dexamethasone are frequently seen within a day and last for about three days. The long-term use of dexamethasone may result in thrush, bone loss, cataracts, easy bruising, or muscle weakness. It is in pregnancy category C in the United S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mutation
In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, mitosis, or meiosis or other types of damage to DNA (such as pyrimidine dimers caused by exposure to ultraviolet radiation), which then may undergo error-prone repair (especially microhomology-mediated end joining), cause an error during other forms of repair, or cause an error during replication ( translesion synthesis). Mutations may also result from substitution, insertion or deletion of segments of DNA due to mobile genetic elements. Mutations may or may not produce detectable changes in the observable characteristics ( phenotype) of an organism. Mutations play a part in both normal and abnormal biological processes including: evolution, cancer, and the development of the immune system, including junctional diversity. Mutati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proline
Proline (symbol Pro or P) is an organic acid classed as a proteinogenic amino acid (used in the biosynthesis of proteins), although it does not contain the amino group but is rather a secondary amine. The secondary amine nitrogen is in the protonated form (NH2+) under biological conditions, while the carboxyl group is in the deprotonated −COO− form. The "side chain" from the α carbon connects to the nitrogen forming a pyrrolidine loop, classifying it as a aliphatic amino acid. It is non-essential in humans, meaning the body can synthesize it from the non-essential amino acid L-glutamate. It is encoded by all the codons starting with CC (CCU, CCC, CCA, and CCG). Proline is the only proteinogenic amino acid which is a secondary amine, as the nitrogen atom is attached both to the α-carbon and to a chain of three carbons that together form a five-membered ring. History and etymology Proline was first isolated in 1900 by Richard Willstätter who obtained the amino a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Obesity
Obesity is a medical condition, considered by multiple organizations to be a disease, in which excess Adipose tissue, body fat has accumulated to such an extent that it can potentially have negative effects on health. People are classified as obese when their body mass index (BMI)—a person's weight divided by the square of the person's height—is over ; the range is defined as overweight. Some East Asian countries use lower values to calculate obesity. Obesity is a major cause of disability and is Obesity-associated morbidity, correlated with various diseases and conditions, particularly cardiovascular diseases, type 2 diabetes, obstructive sleep apnea, certain types of cancer, and osteoarthritis. Obesity has individual, socioeconomic, and environmental causes. Some known causes are Western pattern diet, diet, low physical activity, automation, urbanization, quantitative trait locus, genetic susceptibility, medications, mental disorders, Economic policy, economic pol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
