Dopamine is an organic chemical of the catecholamine and phenethylamine families. It functions both as a hormone and a neurotransmitter, plays several important roles in the brain and body, it is an amine synthesized by removing a carboxyl group from a molecule of its precursor chemical L-DOPA, synthesized in the brain and kidneys. Dopamine is synthesized in plants and most animals. In the brain, dopamine functions as a neurotransmitter—a chemical released by neurons to send signals to other nerve cells; the brain includes several distinct dopamine pathways, one of which plays a major role in the motivational component of reward-motivated behavior. The anticipation of most types of rewards increases the level of dopamine in the brain, many addictive drugs increase dopamine release or block its reuptake into neurons following release. Other brain dopamine pathways are involved in motor control and in controlling the release of various hormones; these pathways and cell groups form a dopamine system, neuromodulatory.
In popular culture and media, dopamine is seen as the main chemical of pleasure, but the current opinion in pharmacology is that dopamine instead confers motivational salience. Outside the central nervous system, dopamine functions as a local paracrine messenger. In blood vessels, it acts as a vasodilator. With the exception of the blood vessels, dopamine in each of these peripheral systems is synthesized locally and exerts its effects near the cells that release it. Several important diseases of the nervous system are associated with dysfunctions of the dopamine system, some of the key medications used to treat them work by altering the effects of dopamine. Parkinson's disease, a degenerative condition causing tremor and motor impairment, is caused by a loss of dopamine-secreting neurons in an area of the midbrain called the substantia nigra, its metabolic precursor L-DOPA can be manufactured. There is evidence that schizophrenia involves altered levels of dopamine activity, most antipsychotic drugs used to treat this are dopamine antagonists which reduce dopamine activity.
Similar dopamine antagonist drugs are some of the most effective anti-nausea agents. Restless legs syndrome and attention deficit hyperactivity disorder are associated with decreased dopamine activity. Dopaminergic stimulants can be addictive in high doses, but some are used at lower doses to treat ADHD. Dopamine itself is available as a manufactured medication for intravenous injection: although it cannot reach the brain from the bloodstream, its peripheral effects make it useful in the treatment of heart failure or shock in newborn babies. A dopamine molecule consists of a catechol structure with one amine group attached via an ethyl chain; as such, dopamine is the simplest possible catecholamine, a family that includes the neurotransmitters norepinephrine and epinephrine. The presence of a benzene ring with this amine attachment makes it a substituted phenethylamine, a family that includes numerous psychoactive drugs. Like most amines, dopamine is an organic base; as a base, it is protonated in acidic environments.
The protonated form is water-soluble and stable, but can become oxidized if exposed to oxygen or other oxidants. In basic environments, dopamine is not protonated. In this free base form, it is less water-soluble and more reactive; because of the increased stability and water-solubility of the protonated form, dopamine is supplied for chemical or pharmaceutical use as dopamine hydrochloride—that is, the hydrochloride salt, created when dopamine is combined with hydrochloric acid. In dry form, dopamine hydrochloride is a fine colorless powder. Dopamine is synthesized in a restricted set of cell types neurons and cells in the medulla of the adrenal glands; the primary and minor metabolic pathways are: Primary: L-Phenylalanine → L-Tyrosine → L-DOPA → Dopamine Minor: L-Phenylalanine → L-Tyrosine → p-Tyramine → Dopamine Minor: L-Phenylalanine → m-Tyrosine → m-Tyramine → DopamineThe direct precursor of dopamine, L-DOPA, can be synthesized indirectly from the essential amino acid phenylalanine or directly from the non-essential amino acid tyrosine.
These amino acids are found in nearly every protein and so are available in food, with tyrosine being the most common. Although dopamine is found in many types of food, it is incapable of crossing the blood–brain barrier that surrounds and protects the brain, it must therefore be synthesized inside the brain to perform its neuronal activity. L-Phenylalanine is converted into L-tyrosine by the enzyme phenylalanine hydroxylase, with molecular oxygen and tetrahydrobiopterin as cofactors. L-Tyrosine is converted into L-DOPA by the enzyme tyrosine hydroxylase, with tetrahydrobiopterin, O2, iron as cofactors. L-DOPA is converted into dopamine by the enzyme aromatic L-amino acid decarboxylase, with pyridoxal phosphate as the cofactor. Dopamine itself is used as precursor in the synthesis o
The Jmol applet, among other abilities, offers an alternative to the Chime plug-in, no longer under active development. While Jmol has many features that Chime lacks, it does not claim to reproduce all Chime functions, most notably, the Sculpt mode. Chime requires plug-in installation and Internet Explorer 6.0 or Firefox 2.0 on Microsoft Windows, or Netscape Communicator 4.8 on Mac OS 9. Jmol operates on a wide variety of platforms. For example, Jmol is functional in Mozilla Firefox, Internet Explorer, Google Chrome, Safari. Chemistry Development Kit Comparison of software for molecular mechanics modeling Jmol extension for MediaWiki List of molecular graphics systems Molecular graphics Molecule editor Proteopedia PyMOL SAMSON Official website Wiki with listings of websites and moodles Willighagen, Egon. "Fast and Scriptable Molecular Graphics in Web Browsers without Java3D". Doi:10.1038/npre.2007.50.1
Cannabidiol is a phytocannabinoid discovered in 1940. It is one of some 113 identified cannabinoids in cannabis plants, accounting for up to 40% of the plant's extract; as of 2018, preliminary clinical research on cannabidiol included studies of anxiety, movement disorders, pain. Cannabidiol can be taken into the body in multiple ways, including by inhalation of cannabis smoke or vapor, as an aerosol spray into the cheek, by mouth, it may be supplied as CBD oil containing only CBD as the active ingredient, a full-plant CBD-dominant hemp extract oil, dried cannabis, or as a prescription liquid solution. CBD does not have the same psychoactivity as THC, may affect the actions of THC. Although in vitro studies indicate CBD may interact with different biological targets, including cannabinoid receptors and other neurotransmitter receptors, as of 2018 the mechanism of action for its biological effects has not been determined. In the United States, the cannabidiol drug Epidiolex has been approved by the Food and Drug Administration for treatment of two epilepsy disorders.
The side effects of long-term use of the drug include somnolence, decreased appetite, fatigue, weakness, sleeping problems. The U. S. Drug Enforcement Administration has assigned Epidiolex a Schedule V classification, while non-Epidiolex CBD remains a Schedule I drug prohibited for any use. Cannabidiol is not scheduled under any United Nations drug control treaties, in 2018 the World Health Organization recommended that it remain unscheduled. There has been little high-quality research into the use of cannabidiol for epilepsy, what there is is limited to refractory epilepsy in children. While the results of using medical-grade cannabidiol in combination with conventional medication shows some promise, they did not lead to seizures being eliminated, were associated with some minor adverse effects. An orally administered cannabidiol solution was approved by the US Food and Drug Administration in June 2018 as a treatment for two rare forms of childhood epilepsy, Lennox-Gastaut syndrome and Dravet syndrome.
Preliminary research on other possible therapeutic uses for cannabidiol include several neurological disorders, but the findings have not been confirmed by sufficient high-quality clinical research to establish such uses in clinical practice. Preliminary research indicates that cannabidiol may reduce adverse effects of THC those causing intoxication and sedation, but only at high doses. Safety studies of cannabidiol showed it is well-tolerated, but may cause tiredness, diarrhea, or changes in appetite as common adverse effects. Epidiolex documentation lists sleepiness and poor quality sleep, decreased appetite and fatigue. Laboratory evidence indicated that cannabidiol may reduce THC clearance, increasing plasma concentrations which may raise THC availability to receptors and enhance its effect in a dose-dependent manner. In vitro, cannabidiol inhibited receptors affecting the activity of voltage-dependent sodium and potassium channels, which may affect neural activity. A small clinical trial reported that CBD inhibited the CYP2C-catalyzed hydroxylation of THC to 11-OH-THC.
Little is known about potential drug interactions but CBD-mediates decrease in clobazam metabolism. Cannabidiol has low affinity for the cannabinoid CB2 receptors. Cannabidiol may be an antagonist of GPR55, a G protein-coupled receptor and putative cannabinoid receptor, expressed in the caudate nucleus and putamen in the brain, it may act as an inverse agonist of GPR3, GPR6, GPR12. CBD has been shown to act as a serotonin 5-HT1A receptor partial agonist, this action may be involved in its antidepressant and neuroprotective effects, it is an allosteric modulator of the μ- and δ-opioid receptors as well. The pharmacological effects of CBD may involve PPARγ intracellular calcium release; the oral bioavailability of CBD is 13 to 19%, while its bioavailability via inhalation is 11 to 45%. The elimination half-life of CBD is 18–32 hours. Cannabidiol is metabolized in the liver as well as in the intestines by CYP2C19 and CYP3A4 enzymes, UGT1A7, UGT1A9, UGT2B7 isoforms. CBD may have a wide margin in dosing.
Nabiximols is a patented medicine containing THC in equal proportions. The drug was approved by Health Canada in 2005 for prescription to treat central neuropathic pain in multiple sclerosis, in 2007 for cancer related pain. In New Zealand, Sativex is "approved for use as an add-on treatment for symptom improvement in people with moderate to severe spasticity due to multiple sclerosis who have not responded adequately to other anti-spasticity medication." Cannabidiol is soluble in organic solvents such as pentane. At room temperature, it is a colorless crystalline solid. In basic media and the presence of air, it is oxidized to a quinone. Under acidic conditions it cyclizes to THC, which occurs during pyrolysis; the synthesis of cannabidiol has been accomplished by several research groups. Cannabis produces CBD-carboxylic acid through the same metabolic pathway as THC, until the next to last step, where CBDA synthase performs catalysis instead of THCA synthase. Cannabinoids were isolated from the cannabis plant in 1940 by Roger Adams, its chemical structure was established in 1963.
Cannabidiol is the generic name of the drug and its INN. Food and beverage products containing CBD were introduced in the United States in 2017. Similar to energy drinks and protein bars which may contain vitamin or herbal additives and beverage items can be infused with CBD as an alternative means of ingesting the substance. In the United S
5-hydroxytryptamine receptors or 5-HT receptors, or serotonin receptors, are a group of G protein-coupled receptor and ligand-gated ion channels found in the central and peripheral nervous systems. They mediate both inhibitory neurotransmission; the serotonin receptors are activated by the neurotransmitter serotonin, which acts as their natural ligand. The serotonin receptors modulate the release of many neurotransmitters, including glutamate, GABA, epinephrine / norepinephrine, acetylcholine, as well as many hormones, including oxytocin, vasopressin, cortisol and substance P, among others; the serotonin receptors influence various biological and neurological processes such as aggression, appetite, learning, mood, nausea and thermoregulation. The serotonin receptors are the target of a variety of pharmaceutical and recreational drugs, including many antidepressants, anorectics, gastroprokinetic agents, antimigraine agents and entactogens. Serotonin receptors are found in all animals and are known to regulate longevity and behavioral aging in the primitive nematode, Caenorhabditis elegans.
5-hydroxytryptamine receptors or 5-HT receptors, or serotonin receptors are found in the central and peripheral nervous systems. They can be divided into 7 families of G protein-coupled receptors except for the 5-HT3 receptor, a ligand-gated ion channel, which activate an intracellular second messenger cascade to produce an excitatory or inhibitory response. In 2014, a novel 5-HT receptor was isolated from the small white butterfly, Pieris rapae, named pr5-HT8, it does not occur in mammals and shares low similarity to the known 5-HT receptor classes. The 7 general serotonin receptor classes include a total of 14 known serotonin receptors; the specific types have been characterized as follows: Note that there is no 5-HT1C receptor since, after the receptor was cloned and further characterized, it was found to have more in common with the 5-HT2 family of receptors and was redesignated as the 5-HT2C receptor. Nonselective agonists of 5-HT receptor subtypes include ergotamine, which activates 5-HT1A, 5-HT1D, 5-HT1B, D2 and norepinephrine receptors.
LSD is a 5-HT2A, 5-HT2C, 5-HT5A, 5-HT5, 5-HT6 agonist. The genes coding for serotonin receptors are expressed across the mammalian brain. Genes coding for different receptors types follow different developmental curves. There is a developmental increase of HTR5A expression in several subregions of the human cortex, paralleled by a decreased expression of HTR1A from the embryonic period to the post-natal one. A number of receptors were classed as "5-HT1-like" - by 1998 it was being argued that, since these receptors were "a heterogeneous population of 5-HT1B, 5-HT1D and 5-HT7" receptors the classification was redundant. Serotonin+Receptors at the US National Library of Medicine Medical Subject Headings "5-Hydroxytryptamine Receptors". IUPHAR Database of Receptors and Ion Channels. International Union of Basic and Clinical Pharmacology. Rubenstein LA, Lanzara RG. "Activation of G protein-coupled receptors entails cysteine modulation of agonist binding". Cogprints. Retrieved 2008-04-11. Paterson LM, Kornum BR, Nutt DJ, Pike VW, Knudsen GM.
"5-HT radioligands for human brain imaging with PET and SPECT". Med Res Rev. 33: 54–111. Doi:10.1002/med.20245. PMC 4188513. PMID 21674551
Simplified molecular-input line-entry system
The simplified molecular-input line-entry system is a specification in the form of a line notation for describing the structure of chemical species using short ASCII strings. SMILES strings can be imported by most molecule editors for conversion back into two-dimensional drawings or three-dimensional models of the molecules; the original SMILES specification was initiated in the 1980s. It has since been extended. In 2007, an open standard called. Other linear notations include the Wiswesser line notation, ROSDAL, SYBYL Line Notation; the original SMILES specification was initiated by David Weininger at the USEPA Mid-Continent Ecology Division Laboratory in Duluth in the 1980s. Acknowledged for their parts in the early development were "Gilman Veith and Rose Russo and Albert Leo and Corwin Hansch for supporting the work, Arthur Weininger and Jeremy Scofield for assistance in programming the system." The Environmental Protection Agency funded the initial project to develop SMILES. It has since been modified and extended by others, most notably by Daylight Chemical Information Systems.
In 2007, an open standard called "OpenSMILES" was developed by the Blue Obelisk open-source chemistry community. Other'linear' notations include the Wiswesser Line Notation, ROSDAL and SLN. In July 2006, the IUPAC introduced the InChI as a standard for formula representation. SMILES is considered to have the advantage of being more human-readable than InChI; the term SMILES refers to a line notation for encoding molecular structures and specific instances should be called SMILES strings. However, the term SMILES is commonly used to refer to both a single SMILES string and a number of SMILES strings; the terms "canonical" and "isomeric" can lead to some confusion when applied to SMILES. The terms are not mutually exclusive. A number of valid SMILES strings can be written for a molecule. For example, CCO, OCC and CC all specify the structure of ethanol. Algorithms have been developed to generate the same SMILES string for a given molecule; this SMILES is unique for each structure, although dependent on the canonicalization algorithm used to generate it, is termed the canonical SMILES.
These algorithms first convert the SMILES to an internal representation of the molecular structure. Various algorithms for generating canonical SMILES have been developed and include those by Daylight Chemical Information Systems, OpenEye Scientific Software, MEDIT, Chemical Computing Group, MolSoft LLC, the Chemistry Development Kit. A common application of canonical SMILES is indexing and ensuring uniqueness of molecules in a database; the original paper that described the CANGEN algorithm claimed to generate unique SMILES strings for graphs representing molecules, but the algorithm fails for a number of simple cases and cannot be considered a correct method for representing a graph canonically. There is no systematic comparison across commercial software to test if such flaws exist in those packages. SMILES notation allows the specification of configuration at tetrahedral centers, double bond geometry; these are structural features that cannot be specified by connectivity alone and SMILES which encode this information are termed isomeric SMILES.
A notable feature of these rules is. The term isomeric SMILES is applied to SMILES in which isotopes are specified. In terms of a graph-based computational procedure, SMILES is a string obtained by printing the symbol nodes encountered in a depth-first tree traversal of a chemical graph; the chemical graph is first trimmed to remove hydrogen atoms and cycles are broken to turn it into a spanning tree. Where cycles have been broken, numeric suffix labels are included to indicate the connected nodes. Parentheses are used to indicate points of branching on the tree; the resultant SMILES form depends on the choices: of the bonds chosen to break cycles, of the starting atom used for the depth-first traversal, of the order in which branches are listed when encountered. Atoms are represented by the standard abbreviation of the chemical elements, in square brackets, such as for gold. Brackets may be omitted in the common case of atoms which: are in the "organic subset" of B, C, N, O, P, S, F, Cl, Br, or I, have no formal charge, have the number of hydrogens attached implied by the SMILES valence model, are the normal isotopes, are not chiral centers.
All other elements must be enclosed in brackets, have charges and hydrogens shown explicitly. For instance, the SMILES for water may be written as either O or. Hydrogen may be written as a separate atom; when brackets are used, the symbol H is added if the atom in brackets is bonded to one or more hydrogen, followed by the number of hydrogen atoms if greater than 1 by the sign + for a positive charge or by - for a negative charge. For example, for ammonium. If there is more than one charge, it is written as digit.
International Standard Serial Number
An International Standard Serial Number is an eight-digit serial number used to uniquely identify a serial publication, such as a magazine. The ISSN is helpful in distinguishing between serials with the same title. ISSN are used in ordering, interlibrary loans, other practices in connection with serial literature; the ISSN system was first drafted as an International Organization for Standardization international standard in 1971 and published as ISO 3297 in 1975. ISO subcommittee TC 46/SC 9 is responsible for maintaining the standard; when a serial with the same content is published in more than one media type, a different ISSN is assigned to each media type. For example, many serials are published both in electronic media; the ISSN system refers to these types as electronic ISSN, respectively. Conversely, as defined in ISO 3297:2007, every serial in the ISSN system is assigned a linking ISSN the same as the ISSN assigned to the serial in its first published medium, which links together all ISSNs assigned to the serial in every medium.
The format of the ISSN is an eight digit code, divided by a hyphen into two four-digit numbers. As an integer number, it can be represented by the first seven digits; the last code digit, which may be 0-9 or an X, is a check digit. Formally, the general form of the ISSN code can be expressed as follows: NNNN-NNNC where N is in the set, a digit character, C is in; the ISSN of the journal Hearing Research, for example, is 0378-5955, where the final 5 is the check digit, C=5. To calculate the check digit, the following algorithm may be used: Calculate the sum of the first seven digits of the ISSN multiplied by its position in the number, counting from the right—that is, 8, 7, 6, 5, 4, 3, 2, respectively: 0 ⋅ 8 + 3 ⋅ 7 + 7 ⋅ 6 + 8 ⋅ 5 + 5 ⋅ 4 + 9 ⋅ 3 + 5 ⋅ 2 = 0 + 21 + 42 + 40 + 20 + 27 + 10 = 160 The modulus 11 of this sum is calculated. For calculations, an upper case X in the check digit position indicates a check digit of 10. To confirm the check digit, calculate the sum of all eight digits of the ISSN multiplied by its position in the number, counting from the right.
The modulus 11 of the sum must be 0. There is an online ISSN checker. ISSN codes are assigned by a network of ISSN National Centres located at national libraries and coordinated by the ISSN International Centre based in Paris; the International Centre is an intergovernmental organization created in 1974 through an agreement between UNESCO and the French government. The International Centre maintains a database of all ISSNs assigned worldwide, the ISDS Register otherwise known as the ISSN Register. At the end of 2016, the ISSN Register contained records for 1,943,572 items. ISSN and ISBN codes are similar in concept. An ISBN might be assigned for particular issues of a serial, in addition to the ISSN code for the serial as a whole. An ISSN, unlike the ISBN code, is an anonymous identifier associated with a serial title, containing no information as to the publisher or its location. For this reason a new ISSN is assigned to a serial each time it undergoes a major title change. Since the ISSN applies to an entire serial a new identifier, the Serial Item and Contribution Identifier, was built on top of it to allow references to specific volumes, articles, or other identifiable components.
Separate ISSNs are needed for serials in different media. Thus, the print and electronic media versions of a serial need separate ISSNs. A CD-ROM version and a web version of a serial require different ISSNs since two different media are involved. However, the same ISSN can be used for different file formats of the same online serial; this "media-oriented identification" of serials made sense in the 1970s. In the 1990s and onward, with personal computers, better screens, the Web, it makes sense to consider only content, independent of media; this "content-oriented identification" of serials was a repressed demand during a decade, but no ISSN update or initiative occurred. A natural extension for ISSN, the unique-identification of the articles in the serials, was the main demand application. An alternative serials' contents model arrived with the indecs Content Model and its application, the digital object identifier, as ISSN-independent initiative, consolidated in the 2000s. Only in 2007, ISSN-L was defined in the