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Hypervitaminosis D
Vitamin D toxicity, or hypervitaminosis D is the toxic state of an excess of vitamin D. The normal range for blood concentration is 20 to 50 nanograms per milliliter (ng/mL). However, the toxic state is known to be a value of 100 ng/ml or more in a clinical setting. Signs and symptoms An excess of vitamin D causes abnormally high blood concentrations of calcium, which can cause overcalcification of the bones, soft tissues, heart and kidneys. In addition, hypertension can result. Symptoms of vitamin D toxicity may include the following: * Dehydration * Vomiting * Diarrhea * Decreased appetite * Irritability * Constipation * Fatigue * Muscle weakness * Metastatic calcification of the soft tissues * Insomnia Symptoms of vitamin D toxicity appear several months after excessive doses of vitamin D are administered. In almost every case, a low-calcium diet combined with corticosteroid drugs will allow for a full recovery within a month. It is possible that some of the symptoms of vi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cholecalciferol
Cholecalciferol, also known as vitamin D3 and colecalciferol, is a type of vitamin D that is made by the skin when exposed to sunlight; it is found in some foods and can be taken as a dietary supplement. Cholecalciferol is made in the skin following UVB light exposure. It is converted in the liver to calcifediol (25-hydroxyvitamin D) which is then converted in the kidney to calcitriol (1,25-dihydroxyvitamin D). One of its actions is to increase calcium uptake by the intestines. It is found in food such as some fish, beef liver, eggs, and cheese. Plant and cow milk, fruit juice, yogurt, and margarine also may have cholecalciferol added to them in some countries, including the United States. Cholecalciferol can be taken as an oral dietary supplement to prevent vitamin D deficiency or as a medication to treat associated diseases, including rickets. It is also used for familial hypophosphatemia, hypoparathyroidism that is causing low blood calcium, and Fanconi syndrome. Vita ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypercalcaemia
Hypercalcemia, also spelled hypercalcaemia, is a high calcium (Ca2+) level in the blood serum. The normal range is 2.1–2.6 mmol/L (8.8–10.7 mg/dL, 4.3–5.2 mEq/L), with levels greater than 2.6 mmol/L defined as hypercalcemia. Those with a mild increase that has developed slowly typically have no symptoms. In those with greater levels or rapid onset, symptoms may include abdominal pain, bone pain, confusion, depression, weakness, kidney stones or an abnormal heart rhythm including cardiac arrest. Most outpatient cases are due to primary hyperparathyroidism and inpatient cases due to cancer. Other causes of hypercalcemia include sarcoidosis, tuberculosis, Paget disease, multiple endocrine neoplasia (MEN), vitamin D toxicity, familial hypocalciuric hypercalcaemia and certain medications such as lithium and hydrochlorothiazide. Diagnosis should generally include either a corrected calcium or ionized calcium level and be confirmed after a week. Specific chang ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Signal Transduction
Signal transduction is the process by which a chemical or physical signal is transmitted through a cell as a series of molecular events, most commonly protein phosphorylation catalyzed by protein kinases, which ultimately results in a cellular response. Proteins responsible for detecting stimuli are generally termed receptors, although in some cases the term sensor is used. The changes elicited by ligand binding (or signal sensing) in a receptor give rise to a biochemical cascade, which is a chain of biochemical events known as a signaling pathway. When signaling pathways interact with one another they form networks, which allow cellular responses to be coordinated, often by combinatorial signaling events. At the molecular level, such responses include changes in the transcription or translation of genes, and post-translational and conformational changes in proteins, as well as changes in their location. These molecular events are the basic mechanisms controlling cell gro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calcitriol
Calcitriol is the active form of vitamin D, normally made in the kidney. It is also known as 1,25-dihydroxycholecalciferol. It is a hormone which binds to and activates the vitamin D receptor in the nucleus of the cell, which then increases the expression of many genes. Calcitriol increases blood calcium (Ca2+) mainly by increasing the uptake of calcium from the intestines. It can be given as a medication for the treatment of low blood calcium and hyperparathyroidism due to kidney disease, low blood calcium due to hypoparathyroidism, osteoporosis, osteomalacia, and familial hypophosphatemia, and can be taken by mouth or by injection into a vein. Excessive amounts or intake can result in weakness, headache, nausea, constipation, urinary tract infections, and abdominal pain. Serious side effects may include high blood calcium and anaphylaxis. Regular blood tests are recommended after the medication is started and when the dose is changed. Calcitriol was identified as the activ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vitamin D-binding Protein
Vitamin D-binding protein (DBP), also/originally known as gc-globulin (group-specific component), is a protein that in humans is encoded by the ''GC'' gene. DBP is genetically the oldest member of the albuminoid family and appeared early in the evolution of vertebrates. Structure Human GC is a glycosylated alpha-globulin, ~58 kDa in size. Its 458 amino acids are coded for by 1690 nucleotides on chromosome 4 (4q11–q13). The primary structure contains 28 cysteine residues forming multiple disulfide bonds. GC contains 3 domains. Domain 1 is composed of 10 alpha helices, domain 2 of 9, and domain 3 of 4. Function Vitamin D-binding protein belongs to the albumin gene family, together with human serum albumin and alpha-fetoprotein. It is a multifunctional protein found in plasma, ascitic fluid, cerebrospinal fluid and on the surface of many cell types. It is able to bind the various forms of vitamin D including ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3), the ... [...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 du ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Equilibrium
In a chemical reaction, chemical equilibrium is the state in which both the Reagent, reactants and Product (chemistry), products are present in concentrations which have no further tendency to change with time, so that there is no observable change in the properties of the system. This state results when the forward reaction proceeds at the same rate as the Reversible reaction, reverse reaction. The reaction rates of the forward and backward reactions are generally not zero, but they are equal. Thus, there are no net changes in the concentrations of the reactants and products. Such a state is known as dynamic equilibrium. Historical introduction The Concept learning, concept of chemical equilibrium was developed in 1803, after Claude Louis Berthollet, Berthollet found that some chemical reactions are Reversible reaction, reversible. For any reaction mixture to exist at equilibrium, the reaction rate, rates of the forward and backward (reverse) reactions must be equal. In the fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ultraviolet
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight, and constitutes about 10% of the total electromagnetic radiation output from the Sun. It is also produced by electric arcs and specialized lights, such as mercury-vapor lamps, tanning lamps, and black lights. Although long-wavelength ultraviolet is not considered an ionizing radiation because its photons lack the energy to ionize atoms, it can cause chemical reactions and causes many substances to glow or fluoresce. Consequently, the chemical and biological effects of UV are greater than simple heating effects, and many practical applications of UV radiation derive from its interactions with organic molecules. Short-wave ultraviolet light damages DNA and sterilizes surfaces with which it comes into contact. F ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cholecalciferol
Cholecalciferol, also known as vitamin D3 and colecalciferol, is a type of vitamin D that is made by the skin when exposed to sunlight; it is found in some foods and can be taken as a dietary supplement. Cholecalciferol is made in the skin following UVB light exposure. It is converted in the liver to calcifediol (25-hydroxyvitamin D) which is then converted in the kidney to calcitriol (1,25-dihydroxyvitamin D). One of its actions is to increase calcium uptake by the intestines. It is found in food such as some fish, beef liver, eggs, and cheese. Plant and cow milk, fruit juice, yogurt, and margarine also may have cholecalciferol added to them in some countries, including the United States. Cholecalciferol can be taken as an oral dietary supplement to prevent vitamin D deficiency or as a medication to treat associated diseases, including rickets. It is also used for familial hypophosphatemia, hypoparathyroidism that is causing low blood calcium, and Fanconi syndrome. Vita ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Recommended Dietary Allowance
The Dietary Reference Intake (DRI) is a system of nutrition recommendations from the National Academy of Medicine (NAM) of the National Academies (United States). It was introduced in 1997 in order to broaden the existing guidelines known as Recommended Dietary Allowances (RDAs, see below). The DRI values differ from those used in nutrition labeling on food and dietary supplement products in the U.S. and Canada, which uses Reference Daily Intakes (RDIs) and Daily Values (%DV) which were based on outdated RDAs from 1968 but were updated as of 2016. Parameters DRI provides several different types of reference values: * Estimated Average Requirements (EAR), expected to satisfy the needs of 50% of the people in that age group based on a review of the scientific literature. * Recommended Dietary Allowances (RDA), the daily dietary intake level of a nutrient considered sufficient by the Food and Nutrition Board of the Institute of Medicine to meet the requirements of 97.5% of health ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Unit
In pharmacology, the international unit (IU) is a unit of measurement for the effect, not mass of a substance; the variance is based on the biological activity or effect, for the purpose of easier comparison across similar ''forms'' of substances. International units are used to quantify vitamins, hormones, some medications, vaccines, blood products, and similar biologically active substances. Many biological agents exist in different forms or preparations (e.g. vitamin A in the form of retinol or ''beta''-carotene). The goal of the IU is to be able to compare these, so that different forms or preparations with the same biological effect will contain the same number of IUs. To do so, the WHO Expert Committee on Biological Standardization provides a reference preparation of the agent, arbitrarily sets the number of IUs contained in that preparation, and specifies a biological procedure to compare other preparations of the same agent to the reference preparation. Since the numb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Unit
In pharmacology, the international unit (IU) is a unit of measurement for the effect, not mass of a substance; the variance is based on the biological activity or effect, for the purpose of easier comparison across similar ''forms'' of substances. International units are used to quantify vitamins, hormones, some medications, vaccines, blood products, and similar biologically active substances. Many biological agents exist in different forms or preparations (e.g. vitamin A in the form of retinol or ''beta''-carotene). The goal of the IU is to be able to compare these, so that different forms or preparations with the same biological effect will contain the same number of IUs. To do so, the WHO Expert Committee on Biological Standardization provides a reference preparation of the agent, arbitrarily sets the number of IUs contained in that preparation, and specifies a biological procedure to compare other preparations of the same agent to the reference preparation. Since the numb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
