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4. UMLS SEMANTIC NETWORK 4.1 Introduction The purpose of the Semantic Network is to provide a consistent categorization of all concepts represented in the UMLS Metathesaurus and to provide a set of useful relations between these concepts. All information about specific concepts is found in the Metathesaurus; the Network provides information about the set of basic semantic types, or categories, which may be assigned to these concepts. The semantic types are the nodes in the Network, and the relations between them are the links. Major groupings have been established for organisms, anatomical structures, biologic function, chemicals, events, physical objects, and concepts or ideas. Each concept in the Metathesaurus has been assigned one or more semantic types from the Network. The assignments are made based on the meanings the concepts have in the source vocabularies. The 1993 release of the Semantic Network includes 132 semantic types. The primary relation is the 'isa' link. This link establishes the hierarchy of types within the Network and is used for deciding on the most specific semantic type available for assignment to a Metathesaurus concept. By traversing the 'isa' links it is possible to compute an interpretation for any given node in the network. A set of 46 non-hierarchical relations between the types is included. These are grouped into four major categories, which are themselves relations: 'physically_related_to', 'temporally_related_to', 'functionally_related_to', and 'conceptually_related_to'. The relations are stated between high level nodes in the Network whenever possible and are generally inherited via the 'isa' link by all the children of those nodes. Thus, for example, the relation 'process_of' is stated to hold between the semantic types 'Biologic Function' and 'Organism'. Therefore, it also holds between 'Organ or Tissue Function' (which is a 'Physiologic Function', which is, in turn, a 'Biologic Function') and 'Animal' (which is an 'Organism'). The fully inherited set of non-hierarchical links has been provided with this release of the Network and is described below in the description of the relational file format. In some cases there will be a conflict between the placement of types in the Network and the link to be inherited. If this is so, the inheritance of the link is said to be blocked. For example, by inheritance the type 'Mental Process' would be 'process_of' 'Plant'. Since plants are not sentient beings, this link is explicitly blocked. In other cases the nature of the relation is such that it should not be inherited by the children of the types that it links. In that case, the relation is defined for the two semantic types it explicitly links, but blocked for all the children of those types. For example, 'conceptual_part_of' links 'Body System' and 'Fully Formed Anatomical Structure', but it should not link 'Body System' to all the children of 'Fully Formed Anatomical Structure'; e.g., a body system is not a conceptual part of a cell. The relations are stated between semantic types and do not necessarily apply to all instances of concepts that have been assigned to those semantic types. That is, the relation may or may not hold between any particular pair of concepts. So, though the relation 'evaluation_of' holds between the semantic types 'Sign' and 'Organism Attribute', a particular sign or a particular attribute may not be linked by this relation. Thus, signs such as "overweight" and "fever" are evaluations of the organism attributes "body weight" and "body temperature", respectively. However, "overweight" is not an evaluation of "body temperature", and "fever" is not an evaluation of "body weight". The relations provided in the Network do not represent all possible relations between semantic types. Rather, they are intended as an initial step in the development of a set which will be useful for retrieval of information from a variety of computerized biomedical databases. The Semantic Network serves as an authority for the semantic types that are assigned to concepts in the Metathesaurus and that are assigned to databases in the Information Sources Map (ISM). The Network defines these types, both with textual descriptions and by means of the information inherent in its hierarchies. It defines the set of relationships that hold between high level semantic types and, in conjunction with the other UMLS knowledge sources, makes these available for the purpose of enhancing existing information retrieval methods. The UMLS Semantic Network is provided in two formats; a relational table format and a unit record format. Differences between the 1992 and 1993 Experimental Editions: The 1993 edition of the Semantic Network contains has combined the types 'Sign' and 'Symptom' into one new type 'Sign or Symptom', and no longer has the type 'Gene Product'. One additional relational table is included with the Network files. This table is an expansion of the Network structure table and gives the fully inherited set of non-hierarchical links represented in the Network, expressed as triples of semantic type and relation names. Co-occurrence Information Groupings of semantic types have been established for the purpose of displaying MEDLINE co-occurrence information. These 14 high-level groupings appear in the MetaCard application on the "occurs" screen and are listed in Appendix D. Labelled MeSH relationships Several portions of the MeSH hierarchy have been labelled with child to parent semantic relationships. All of sections A (Anatomy), C (Diseases), and F (Psychiatry and Psychology) have been labelled, as well as sub-trees 4-11 in section G (Biological Sciences). The `isa' relation and all non-hierarchical relations in the Semantic Network are valid for use in this labelling. One additional relation is used: 'equivalent_to'. The links that are expressed between MeSH terms are, with some exceptions, reflected in the Semantic Network. That is, if two MeSH terms are linked by a certain relation, then that link is expressed in the Network as a link between the semantic types that have been assigned to those MeSH terms. For example, "Amniotic Fluid", which is a 'Body Substance', is a child of "Embryo", which is an 'Embryonic Structure'. The labelled relationship is 'surrounds'. Therefore, the link "Body Substance surrounds Embryonic Structure" is represented in the Network. In a few cases the links are not represented in the Network. By convention, each instance of a semantic type can be in an 'isa' relation to other instances of the same semantic type. For example, if in the MeSH file a child term is an instance of a 'Disease or Syndrome' and if it is linked by 'isa' to the parent term which is also a 'Disease or Syndrome', then the link "Disease or Syndrome isa Disease or Syndrome" holds. In some cases MeSH terms that are linked by the 'associated_with' relationship are not represented in the Network because they were felt to be too specific to the MeSH structure itself. 4.3 Semantic Network ASCII Relational Format There are two basic tables and two ancillary tables included in this format. The two basic tables contain exactly the same information as the unit record file, but the information is presented somewhat differently. One table contains definitional information about the semantic types and relations; the other contains information about the structure of the Network. Each semantic type and each relation has been assigned a 4 character unique identifier (UI). These are of the form "T001", "T002", etc. The ancillary tables are expansions of the table that contains the Network structure. They give the fully inherited set of non-hierarchical links represented in the Network. The first table is expressed as triples of UI's. The second is expressed as triples of names. Fields in all tables are separated by a "|". The tables are listed and described below: SRDEF Basic information about the Semantic Types and Relations. SRSTR Structure of the Network. SRSTRE1 Fully inherited set of non-hierarchical Relations (UIs). SRSTRE2 Fully inherited set of non-hierarchical Relations (names). Specific Descriptions of each Table: Table: SRDEF Field 1: Record Type (STY = Semantic Type or RL = Relation). Field 2: Unique Identifier of the Semantic Type or Relation. Field 3: Name of the Semantic Type or Relation. Field 4: Tree Number of the Semantic Type or Relation. Field 5: Definition of the Semantic Type or Relation. Field 6: Abbreviation of the Relation Name (RL records only). Field 7: Inverse of the Relation (RL records only). Table: SRSTR Field 1: Argument 1 (Name of a Semantic Type or Relation). Field 2: Relation ('isa' or the name of a non-hierarchical Relation). Field 3: Argument 2 (Name of a Semantic Type or Relation); if this field is blank this means that the Semantic Type or Relation is one of the top nodes of the Network. Field 4: Link Status (D = Defined for the Arguments and its children; B = Blocked; DNI = Defined but Not Inherited by the children of the Arguments). N.B.: The relations expressed in this table are binary relations and the arguments are ordered pairs. The relations are stated only for the top-most node of the 'isa' hierarchy of the Semantic Types to which they may apply. Table: SRSTRE1 or SRSTRE2 Field 1: Argument 1 (UI or name of a Semantic Type). Field 2: Relation (UI or name of a non-hierarchical Relation). Field 3: Argument 2 (UI or name of a Semantic Type). N.B.: The relations expressed in this table are binary relations and the arguments are ordered pairs. The non-hierarchical relations have been fully inherited in this table. 4.4 Semantic Network ASCII Unit Record Format The file "SU" contains individual records for both semantic types and relations. Each record begins with a unique identifier field (UI) which contains the 4 character UI. These are of the form "T001", "T002", etc. Each field in a record begins on a new line and may continue over several lines. If "<none>" appears in a field, that means there is no value for that field. Semantic Type records contain the following fields: UI: Unique Identifier of the Semantic Type. STY: Name of the Semantic Type. STN: Tree Number of the Semantic Type. DEF: Definition of the Semantic Type. HL: Hierarchical links of the Semantic Type to its parent ({isa}) and its children ({inverse_isa}). If there is no parent listed, this means that the Semantic Type has no parent and is one of the top nodes of the Network. Relation records contain the following fields: UI: Unique Identifier of the Relation. RL: Name of the Relation. ABR: Abbreviation of the Relation. RIN: Name of the inverse of the Relation. RTN: Tree Number of the Relation. DEF: Definition of the Relation. INH: "N" if the relation is not inherited; field otherwise does not occur. HL: Hierarchical links of the Relation to its parent ({isa}) and its children ({inverse_isa}). If there is no parent listed, this means that the Relation has no parent and is one of the top nodes of the Network. STL: Semantic Types linked by this Relation. N.B.: These are binary relations and the arguments are ordered pairs. The relations are stated only for the top-most node of the 'isa' hierarchy of the Semantic Types to which they may apply. STLB: Semantic Types linked by this Relation are blocked; field otherwise does not occur 4.5 Semantic Network Browser The Semantic Network Browser is a Macintosh application that allows the user to browse the Semantic Network. The Browser reads a file in unit record format. The unit record file included with the Browser (called "UMLS Net") is a slight augmentation of the "SU" file described above. (See below for a brief description of the differences). Using the Browser: The Semantic Network Browser will run on the Apple Macintosh family of computers, will work with MultiFinder, and requires System 6.0 or later. To use the Browser, double-click on the application icon. The Menu bar will change and an information box will be displayed. The user can click on the information box to make it go away. Choose Open from the File menu. Choose "UMLS Net" (or the name of any other appropriately constructed file) from the file selection dialog. The cursor will change to indicate processing is underway; in a few seconds the top-most nodes of the Semantic Network will be displayed. The leftmost item (displayed in 18-point type and in red on color monitors) indicates the user's current position. The items in the column to the right (displayed in 14-point type and in green on color monitors) are one step away from the current position. A line connecting items indicates a relation between them. A heavy line indicates an 'isa' relation (or its inverse). The name of the relation is indicated by a two-letter abbreviation (e.g., is); the inverse of the relation is indicated by a trailing apostrophe (e.g., is'). Single-click on an item to select it. Selected items are highlighted to indicate the selection. Double-click on any item to move that item to the leftmost position; the display will change accordingly. If the last item viewed is still visible in the current display, it is outlined by a box. If the mouse is clicked on either the line or the two-letter abbreviation representing a relation, a pop-up appears that gives the unabbreviated name of the relation. Network properties (i.e., 'isa', 'inverse_isa' a relation's inverse, and a relation's domain) are shown within parentheses; relations defined in the data file are not. If the mouse is double-clicked within the pop-up, the relation then becomes the current (leftmost) position. The resultant display shows the relation, its domain (the class of items to which it applies), its inverse, and the domain of its inverse. If the relation is related to other relations (via the 'isa' relation), they will also be shown. Note that a relation's inverse is displayed below it, within the same column. MENUS The Open (or Close) option of the File menu allows the user to open (close) a specially constructed text file (e.g., "UMLS Net"). The Page Setup and Print options of the File menu can be used to print a copy of the current display. Quit quits the application. The Copy option of the Edit menu can be used to copy a selected item into the clipboard. A selected item is any item that is highlighted, including the pop-up full name of a relation. The Find option in the Options menu presents a dialog box that allows the user to search for an item. The user may enter the whole item, one or more words from the item (in any order), or just the initial letters from words in the item. All matching items are displayed in a list from which the user may select an item to view. The Definition option in the Options menu displays the definition of a selected type or relation in a separate window, which may then be closed or left open, as desired. If no item is selected, the definition of the current (i.e., leftmost) item is displayed. The tree number of the item, if specified in the data file, is shown at the lower left; its unique identifier is shown at the lower right. Note that the Options, Treetops, and Last Ten menus will not be usable while the Definitions window is the foremost window. The Depth option in the Options menu presents a submenu from which the user can choose to display items that are up to one, two, or more steps away from the current item. Items that are a single step away from the current item are displayed in 14-point green type. Items that are two or more steps away from the current item are displayed in 12-point black type. Note that if the browser runs out of memory while trying to generate a display and the depth is greater than one, it will set the depth to one and try again. The Relations option in the Options menu presents a dialog box that allows the user to specify which relations should be displayed. The user chooses from a list of all of the relations that were defined in the data file. One or more items can be selected from this list by dragging along contiguous items or by clicking separate items. In addition, the user can choose the Depth of the display and whether or not the 'isa' relation is to be displayed. All relations and the 'isa' relation can be selected (or deselected) at once with the "Select All" (or "Deselect All") button. Clicking on "OK" displays the results of the user's choices. The Treetops menu is a navigational aid to position the user at the top of one of the trees in the collection (i.e., the item selected will become the leftmost item in the display). The items in this menu indicate distinct trees in the network. Note that both relations and semantic types can be organized into trees. The Last Ten menu is provided as a navigational aid. It displays a list of the ten most recent items or phrases selected by the user during the current session and can be used to go immediately to a previous position. A USEFUL EXERCISE The entire hierarchy of semantic types can be displayed by using the Relations option in the Options menu. Click on "Deselect All", check 'isa' and select the "top_level_of" relation in the list of relations (located almost at the bottom of the list). Set the depth to infinity and click "OK". These settings cause the browser to show only the 'isa' and "top_level_of" relations (and their inverse relations) and to display all semantic types in the network that can be reached from the current semantic type by following these relations repeatedly. Position the display at "* Semantic Network", if it isn't there already. ("* Semantic Network" acts as a root for all of the isa hierarchies into which the semantic types are organized. The "top_level_of" relation links "* Semantic Network" with the top of each isa hierarchy.) This display can be printed but will have to be cut and pasted together as it covers several 8 1/2 by 11 pages, depending on the settings for the Print Options item in the File menu. Differences between the "SU" and "UMLS Net" Files: The unit record file included with the Browser (called "UMLS Net") is a slight augmentation of the "SU" file described earlier. One additional node and one additional link have been added. The additions appear at the end of the UMLS Net file and are given the Unique Identifiers G01-G02. The file was augmented for display purposes only. The augmentation allows the user to see the top-level nodes in the network when first starting the application. RL: adjacent_to DEF: Close to, near or abutting another physical unit with no other structure of the same kind intervening. This includes adjoins, abuts, is contiguous to, is juxtaposed, and is close to. RL: affects DEF: Produces a direct effect on. Implied here is the altering or influencing of an existing condition, state, situation, or entity. This includes has a role in, alters, influences, predisposes, catalyzes, stimulates, regulates, depresses, impedes, enhances, contributes to, leads to, and modifies. RL: assesses_effect_of DEF: Analyzes the influence or consequences of the function or action of. RL: associated_with DEF: has a significant or salient relationship to. RL: carries_out DEF: Executes a function or performs a procedure or activity. This includes transacts, operates on, handles, and executes. RL: causes DEF: Brings about a condition or an effect. Implied here is that an agent, such as for example, a pharmacologic substance or an organism, has brought about the effect. This includes induces, effects, evokes, and etiology. RL: co-occurs_with DEF: Occurs at the same time as, together with, or jointly. This includes is co-incident with, is concurrent with, is contemporaneous with, accompanies, coexists with, and is concomitant with. RL: complicates DEF: Causes to become more severe or complex or results in adverse effects. RL: conceptual_part_of DEF: Conceptually a portion, division, or component of some larger whole. INH: N RL: conceptually_related_to DEF: Related by some abstract concept, thought, or idea. INH: N RL: connected_to DEF: Directly attached to another physical unit as tendons are connected to muscles. This includes attached to and anchored to. RL: consists_of DEF: Is structurally made up of in whole or in part of some material or matter. This includes composed of, made of, and formed of. RL: contains DEF: Holds or is the receptacle for fluids or other substances. This includes is filled with, holds, and is occupied by. RL: degree_of DEF: The relative intensity of a process or the relative intensity or amount of a quality or attribute. RL: derivative_of DEF: In chemistry, a substance structurally related to another or that can be made from the other substance. This is used only for structural relationships. This does not include functional relationships such as metabolite of, by product of, nor analog of. RL: developmental_form_of DEF: An earlier stage in the individual maturation of. RL: diagnoses DEF: Distinguishes or identifies the nature or characteristics of. RL: disrupts DEF: Alters or influences an already existing condition, state, or situation. Produces a negative effect on. RL: evaluation_of DEF: Judgment of the value or degree of some attribute or process. RL: exhibits DEF: Shows or demonstrates. RL: functionally_related_to DEF: Related by the carrying out of some function or activity. RL: indicates DEF: Gives evidence for the presence at some time of an entity or process. RL: interacts_with DEF: Acts, functions, or operates together with. RL: interconnects DEF: Serves to link or join together two or more other physical units. This includes joins, links, conjoins, articulates, separates, and bridges. RL: issue_in DEF: Is an issue in or a point of discussion, study, debate, or dispute. RL: location_of DEF: The position, site, or region of an entity or the site of a process. RL: manages DEF: Administers, or contributes to the care of an individual or group of individuals. RL: manifestation_of DEF: That part of a phenomenon which is directly observable or concretely or visibly expressed, or which gives evidence to the underlying process. This includes expression of, display of, and exhibition of. RL: measurement_of DEF: The dimension, quantity, or capacity determined by measuring. RL: measures DEF: Ascertains or marks the dimensions, quantity, degree, or capacity of. RL: method_of DEF: The manner and sequence of events in performing an act or procedure. RL: occurs_in DEF: Takes place in or happens under given conditions, circumstances, or time periods, or in a given location or population. This includes appears in, transpires, comes about, is present in, and exists in. RL: part_of DEF: Composes, with one or more other physical units, some larger whole. This includes component of, division of, portion of, fragment of, section of, and layer of. RL: physically_related_to DEF: Related by virtue of some physical attribute or characteristic. RL: practices DEF: Performs habitually or customarily. RL: precedes DEF: Occurs earlier in time. This includes antedates, comes before, is in advance of, predates, and is prior to. RL: prevents DEF: Stops, hinders or eliminates an action or condition. RL: process_of DEF: Action, function, or state of. RL: produces DEF: Brings forth, generates or creates. This includes yields, secretes, emits, biosynthesizes, generates, releases, discharges, and creates. RL: property_of DEF: Characteristic of, or quality of. RL: result_of DEF: The condition, product, or state occurring as a consequence, effect, or conclusion of an activity or process. This includes product of, effect of, sequel of, outcome of, culmination of, and completion of. RL: surrounds DEF: Establishes the boundaries for, or defines the limits of another physical structure. This includes limits, bounds, confines, encloses, and circumscribes. RL: temporally_related_to DEF: Related in time by preceding, co-occuring with, or following. RL: traverses DEF: Crosses or extends across another physical structure or area. This includes crosses over and crosses through. RL: treats DEF: Applies a remedy with the object of effecting a cure or managing a condition. RL: uses DEF: Employs in the carrying out of some activity. This includes applies, utilizes, employs, and avails. STY: Acquired Abnormality DEF: An abnormal structure, or one that is abnormal in size or location, found in or deriving from a previously normal structure. Metathesaurus examples include "Hernia", "Fistula", "Hemorrhoids", and "Varicose Veins". STY: Activity DEF: An operation or series of operations that an organism or machine carries out or participates in. The children of this type in the network are 'Behavior', 'Daily or Recreational Activity', 'Occupational Activity', and 'Machine Activity'. Metathesaurus examples include "Development Planning", "Expeditions", "Information Distribution", "Migration", and "Voting". STY: Age Group DEF: An individual or individuals classified according to their age. Metathesaurus examples include "Adult", "Infant, Premature", "Adolescents", and "Octogenarian". STY: Alga DEF: A chiefly aquatic plant that contains chlorophyll, but does not form embryos during development and lacks vascular tissue. Metathesaurus examples include "Chlorella", "Laminaria", "Seaweed", and "Anabaena". STY: Alkaloid DEF: A basic, nitrogen-containing compound of plant origin. Included here are aporphines, cinchona, curare, ergot, opium, belladonna, rauwolfia, and vinca alkaloids, among others. Metathesaurus examples include "Quinidine", "Aconitine", "3-Hydroxy-N-Methylmorphinan", "Vincamine", and "Rauwolfia Alkaloids". STY: Amino Acid Sequence DEF: The sequence of amino acids as arrayed in chains, sheets, etc., within the protein molecule. It is of fundamental importance in determining protein structure. STY: Amino Acid, Peptide, or Protein DEF: Amino acids and chains of amino acids connected by peptide linkages. Metathesaurus examples include "Glycoproteins", "Myoglobin", "Alanine", "Sulfatase", and "Acetylcysteine". STY: Amphibian DEF: A cold-blooded, smooth-skinned vertebrate which characteristically hatches as an aquatic larva, breathing by gills. When mature, the amphibian breathes with lungs. Metathesaurus examples include "Salamandra", "Urodela", and "Frog". STY: Anatomical Structure DEF: A normal or pathological part of the anatomy or structural organization of an organism. If the term refers to a structure found only in non-humans, the Non-Human flag is assigned as well. Examples of this would be such terms as "Feathers", "Gills", and "Horns". The children of this type in the network are 'Embryonic Structure', 'Congenital Abnormality', 'Acquired Abnormality', and 'Fully Formed Anatomical Structure'. STY: Animal DEF: An organism with eukaryotic cells, and lacking stiff cell walls, plastids and photosynthetic pigments. The children of this type in the network are 'Invertebrate', and 'Vertebrate'. Metathesaurus examples include "Animals, Poisonous", "Animals, Newborn", and "Animals, Laboratory". STY: Bacterium DEF: A small, typically one-celled, prokaryotic micro-organism. Metathesaurus examples include "Bacillus cereus", "Acetobacter", "Bordetella pertussis", and "Cytophaga". STY: Behavior DEF: Any of the activities of humans or animals that can be observed directly by others or can be made systematically observable by the use of special strategies. If the term refers to a behavior exhibited only by non-humans, the Non-Human flag is assigned as well. The children of this type in the network are 'Social Behavior', and 'Individual Behavior'. STY: Biologic Function DEF: A state, activity or process of the body or one of its systems or parts. If the term refers to a biologic function found only in non-humans, the Non-Human flag is assigned as well. The children of this type in the network are 'Physiologic Function', and 'Pathologic Function'. STY: Biologically Active Substance DEF: A substance produced or required by an organism, of primary interest because of its role in the biologic functioning of the organism that produces it. The children of this type in the network are 'Neuroreactive Substance or Biogenic Amine', 'Hormone', 'Enzyme', 'Vitamin', 'Prostaglandin', and 'Immunologic Factor'. Metathesaurus examples include "Myelin", "Gastric Acid", "Growth Substances", and "Enzyme Precursors". STY: Biomedical Occupation or Discipline DEF: A vocation, academic discipline, or field of study related to biomedicine. Metathesaurus examples include "Dermatology", "Emergency Nursing", "Dentistry", "Family Practice", and "Cellular Neurobiology". STY: Biomedical or Dental Material DEF: A substance used in biomedicine or dentistry predominantly for its physical, as opposed to chemical, properties. Included here are biocompatible materials, tissue adhesives, bone cements, resins, etc. Metathesaurus examples include "Anion Exchange Resins", "Dental Casting Investment", "Elastosil", "Bone Cements", and "Drug Implants". STY: Bird DEF: A vertebrate having a constant body temperature and characterized by the presence of feathers. Metathesaurus examples include "Canaries", "Pigeons", and "Quail". STY: Body Location or Region DEF: An area, subdivision, or region of the body demarcated for the purpose of topographical description. If the term refers to a body location or region found only in non-humans, the Non-Human flag is assigned as well. Metathesaurus examples include "Abdomen", "Thorax", "Back", and "Gluteal Region". STY: Body Part, Organ, or Organ Component DEF: A collection of cells and tissues which are localized to a specific area or combine and carry out one or more specialized functions of an organism. This ranges from gross structures to small components of complex organs. These structures are relatively localized in comparison to tissues. Metathesaurus examples include "Eye", "Liver", "Pulmonary Artery", and "Laryngeal Mucosa". STY: Body Space or Junction DEF: An area enclosed or surrounded by body parts or organs or the place where two anatomical structures meet or connect. If the term refers to a body space or junction found only in non-humans, the Non-Human flag is assigned as well. Metathesaurus examples include "Synapses", "Peritoneal Cavity", "Neuromuscular Junction", and "Knee Joint". STY: Body Substance DEF: Extracellular material, or mixtures of cells and extracellular material, produced, excreted, or accreted by the body. Included here are substances such as saliva, dental enamel, sweat, and gastric acid. If the term refers to a body substance found only in non-humans, the Non-Human flag is assigned as well. Metathesaurus examples include "Saliva", "Necrotic debris", "Mucus", and "Amniotic Fluid". STY: Body System DEF: A complex of anatomical structures that performs a common function. Metathesaurus examples include "Renin-Angiotensin System", "Limbic System", "Skeleton", and "Reticuloendothelial System". STY: Carbohydrate Sequence DEF: The sequence of carbohydrates within polysaccharides, glycoproteins, and glycolipids. STY: Carbohydrate DEF: A compound consisting of carbon, hydrogen, and oxygen in which the hydrogen/oxygen ratio is the same as in water, and in which repeating units are joined through oxygen linkages. Carbohydrates are generally characterized as sugars and include mono-, di-, oligo-, and polysaccharides, glycosides, glycans, and starches. Included here are sugar phosphates. Excluded are glycolipids. Metathesaurus examples include "Glycosides", "Polysaccharides", "Deoxyglucose", and "Sepharose". STY: Cell Component DEF: A part of a cell or the intercellular matrix, generally visible by light microscopy. Metathesaurus examples include "Golgi Apparatus", "Microsomes", and "Organelles". STY: Cell Function DEF: A physiologic function inherent to cells or cell components. Metathesaurus examples include "Cell Division", "Cell Cycle", "Erythrocyte Aggregation", and "Lymphocyte Transformation". STY: Cell or Molecular Dysfunction DEF: A pathologic function inherent to cells, parts of cells, or molecules. Metathesaurus examples include "Cellular necrosis", "Wallerian Degeneration", "Cell Transformation, Neoplastic", and "DNA Damage". STY: Cell DEF: The fundamental structural and functional unit of living organisms. Metathesaurus examples include "Erythrocytes", "Dendritic Cells", and "Histiocytes". STY: Chemical Viewed Functionally DEF: A chemical viewed from the perspective of its functional characteristics or pharmacological activities. The children of this type in the network are 'Pharmacologic Substance', 'Biomedical or Dental Material', 'Biologically Active Substance', 'Indicator or Reagent', and 'Hazardous or Poisonous Substance'. Metathesaurus examples include "Aerosol Propellants", "Soaps", and "Food Additives". STY: Chemical Viewed Structurally DEF: A chemical viewed from the perspective of its structural characteristics. Included here are terms which can mean either a salt, an ion, or a compound (e.g., "Bromates" and "Bromides"). The children of this type in the network are 'Inorganic Chemical', and 'Organic Chemical'. Metathesaurus examples include "Free Radicals", "Onium Compounds", "Salts", and "Sulfur Compounds". STY: Chemical DEF: Chemicals are viewed from two distinct perspectives in the network, functionally and structurally. Almost every chemical term is assigned at least two types, one from the structure hierarchy and at least one from the function hierarchy. The children of this type in the network are 'Chemical Viewed Functionally', and 'Chemical Viewed Structurally'. STY: Conceptual Entity DEF: A broad type for grouping abstract entities or concepts. The children of this type in the network are 'Idea or Concept', 'Finding', 'Organism Attribute', 'Intellectual Product', 'Language', 'Occupation or Discipline', 'Organization', 'Group Attribute', and 'Group'. STY: Congenital Abnormality DEF: An abnormal structure, or one that is abnormal in size or location, present at birth or evolving over time as a result of a defect in embryogenesis. Metathesaurus examples include "Congenital cranial meningocele" and "Syndactylia". STY: Daily or Recreational Activity DEF: An activity carried out for recreation or exercise. Metathesaurus examples include "Swimming", "Camping", "Child Care", and "Exercise". STY: Diagnostic Procedure DEF: A procedure, method, or technique used to determine the nature or identity of a disease or disorder. This excludes procedures which are primarily carried out on specimens in a laboratory. Metathesaurus examples include "Electrocardiography", "Ultrasonography", "Heart Auscultation", and "Personality Assessment". STY: Disease or Syndrome DEF: A condition which alters or interferes with a normal process, state, or activity of an organism. It is usually characterized by the abnormal functioning of one or more of the host's systems, parts, or organs. Included here is a complex of symptoms descriptive of a disorder. This type has one child in the network, 'Mental or Behavioral Dysfunction'. Metathesaurus examples include "Diabetes Mellitus", "Brain Neoplasms", "Nephrotic Syndrome", "Dumping Syndrome", and "Malabsorption Syndromes". STY: Educational Activity DEF: An activity related to the organization and provision of education. Metathesaurus examples include "Community Health Education", "Preceptorship", "Academic Training", and "Family Planning Training". STY: Eicosanoid DEF: A compound structurally related to arachidonic acid. Included here are arachidonic acid, eicosanoic acid, and saturated or unsaturated derivatives of each. Metathesaurus examples include "Thromboxane B2", "n-Eicosanoic acid", "8,11,14-Eicosatrienoic Acid", and "Leokotriene C-4". STY: Element or Ion DEF: One of the 109 presently known kinds of substance that comprise all matter at and above the atomic level. This includes elemental metals, rare gases, and naturally occurring radioactive elements, as well as the ionic counterparts of elements. This does not include the less abundant isotopic forms, for which the type 'Isotope' is assigned. Metathesaurus examples include "Aluminum", "Carbon", "Uranium", "Beryllium", and "Oxygen Ion". STY: Embryonic Structure DEF: An anatomical structure that exists only before the organism is fully formed; in mammals, for example, a structure that exists only prior to the birth of the organism. This structure may be normal or abnormal. Metathesaurus examples include "Neural Crest", "Blastoderm", and "Fetal Heart". STY: Entity DEF: A physical or conceptual entity. The children of this type in the network are 'Physical Object', and 'Conceptual Entity'. STY: Environmental Effect of Humans DEF: A change in the natural environment that is a result of the activities of human beings. Metathesaurus examples include "Water Pollution", "Acid Rain", "Soil Degradation", and "Smog". STY: Enzyme DEF: A complex protein that is produced by living cells and which catalyzes specific biochemical reactions. There are six main types of enzymes, oxidoreductases, transferases, hydrolases, lyases, isomerases, and ligases. Metathesaurus examples include "ATP Citrate Lyase", "Acetyl CoA Acetyltransferase", "Complement Activating Enzymes", and "Glucose Oxidase". STY: Event DEF: A broad type for grouping activities, processes and states. The children of this type in the network are 'Activity', and 'Phenomenon or Process'. STY: Experimental Model of Disease DEF: A representation in a non-human organism of a human disease for the purpose of research into its mechanism or treatment. Metathesaurus examples include "Avian Leukosis", "Streptozotocin Diabetes", "Ehrlich Ascites Tumor", and "Melanoma, Experimental". STY: Family Group DEF: An individual or individuals classified according to their family relationships or relative position in the family unit. Metathesaurus examples include "Only Child", "Single Parent", "Surrogate Mothers", and "Twins". STY: Finding DEF: That which is discovered by direct observation or measurement of an organism attribute or condition, including the clinical history of the patient. The children of this type in the network are 'Laboratory or Test Result' and 'Sign or Symptom'. Metathesaurus examples include "Occupational problem", "Birth History", and "Downward displacement of diaphragm". STY: Fish DEF: A cold-blooded aquatic vertebrate characterized by fins and breathing by gills. Included here are fishes having either a bony skeleton, such as a perch, or a cartilaginous skeleton, such as a shark, or those lacking a jaw, such as a lamprey or hagfish. Metathesaurus examples include "Bass", "Eels", and "Carp". STY: Food DEF: Any substance containing nutrients, such as carbohydrates, proteins, and fats, that can be ingested by a living organism and metabolized into energy and body tissue. Some foods are naturally occurring, others are either partially or entirely made by humans. Metathesaurus examples include "Egg Yolk", "Nuts", "Beverages", and "Margarine". STY: Fully Formed Anatomical Structure DEF: An anatomical structure in a fully formed organism; in mammals, for example, a structure in the body after the birth of the organism. The children of this type in the network are 'Body Part, Organ, or Organ Component', 'Tissue', 'Cell', 'Cell Component', and 'Macromolecular Structure'. They are linked to each other by the part_of relationship in the network. Thus, a Macromolecular Structure is part of a Cell Component, which is part of a Cell, etc. A term is assigned to the most specific type available. STY: Functional Concept DEF: A concept which is of interest because it pertains to the carrying out of a process or activity. This type has one child in the network, 'Body System'. Metathesaurus examples include "Solar System". STY: Fungus DEF: A eukaryotic organism characterized by the absence of chlorophyll and the presence of a rigid cell wall. Included here are both slime molds and true fungi such as yeasts, molds, mildews, and mushrooms. Metathesaurus examples include "Blastomyces", "Neurospora", "Aspergillus clavatus", and "Helminthosporium". STY: Gene or Genome DEF: A specific sequence, or in the case of the genome the complete sequence, of nucleotides along a molecule of DNA or RNA (in the case of some viruses) which represent the functional units of heredity. Metathesaurus examples include "Alleles", "Genes, Structural", "Genome, Human", and "c-Ha-ras Genes". STY: Genetic Function DEF: Functions of or related to the maintenance, translation or expression of the genetic material. Metathesaurus examples include "Amino Acid Activation", "Early Gene Transcription", "Gene Amplification", and "RNA Splicing". STY: Geographic Area DEF: A geographic location, generally having definite boundaries. Metathesaurus examples include "Canada", "Baltimore", "Far East", "Arctic Regions", and "Cities". STY: Governmental or Regulatory Activity DEF: An activity carried out by officially constituted governments, or an activity related to the creation or enforcement of the rules or regulations governing some field of endeavor. Metathesaurus examples include "Facility Regulation and Control", "Public Assistance", "Credentialing", and "Certification". STY: Group Attribute DEF: A conceptual entity which refers to the frequency or distribution of certain characteristics or phenomena in certain groups. Metathesaurus examples include "Neonatal Mortality", "Life Expectancy", "Family Size", "Population Characteristics", and "Group Structure". STY: Group DEF: A conceptual entity referring to the classification of individuals according to certain shared characteristics. The children of this type in the network are 'Professional or Occupational Group', 'Population Group', 'Family Group', 'Age Group', and 'Patient or Disabled Group'. STY: Hazardous or Poisonous Substance DEF: A substance of concern because of its potentially hazardous or toxic effects. This would include most drugs of abuse, as well as agents that require special handling because of their toxicity. Most pharmaceutical agents, although potentially harmful, are excluded here and are assigned to the type 'Pharmacologic Substance'. Metathesaurus examples include "Paraquat", "Crack Cocaine", "Plant poison", "Carcinogens", and "Sodium Cyanide". STY: Health Care Activity DEF: An activity of or relating to the practice of medicine or involving the care of patients. The children of this type in the network are 'Diagnostic Procedure', 'Laboratory Procedure', and 'Therapeutic or Preventive Procedure'. Metathesaurus examples include "Preventive Health Services", "Ambulatory Care", "Clinic Activities", and "Geriatric Nursing". STY: Health Care Related Organization DEF: An established organization which carries out specific functions related to health care delivery or research in the life sciences. Terms for health care related professional societies are assigned the type Professional Society. Metathesaurus examples include "American Cancer Society", "Health Care Coalitions", "Ambulatory Care Facilities", and "Pan American Health Organization". STY: Hormone DEF: In animals, a chemical secreted by an endocrine gland whose products are released into the circulating fluid. Plant hormones or synthetic hormones which are used only to alter or control various physiologic processes, e.g., reproductive control agents, are assigned only to the type 'Pharmacologic Substance'. Hormones act as chemical messengers and regulate various physiologic processes such as growth, reproduction, metabolism, etc. They usually fall into two broad classes, steroid hormones and peptide hormones. Metathesaurus examples include "Gonadotropins", "Epicortisol", "Glucocorticoids", "Pentagastrin", and "MSH Release Inhibiting Hormone". STY: Human-caused Phenomenon or Process DEF: A phenomenon or process that is a result of the activities of human beings. If the term refers to the activity itself, rather than the result of that activity, a type from the 'Activity' hierarchy is assigned instead. This type has one child in the network, 'Environmental Effect of Humans'. Metathesaurus examples include "Social Change", "Baby Boom", and "International Cooperation". STY: Human DEF: Modern man, the only remaining species of the Homo genus. If a term describes a human being from the point of view of occupational, family, social status, etc., then a type from the 'Group' hierarchy is assigned instead. A small number of Metathesaurus terms has been assigned this type, e.g., "Hominidae", "Man", and "Homo sapiens". STY: Idea or Concept DEF: An abstract concept, such as a social, religious or philosophical concept. The children of this type in the network are 'Temporal Concept', 'Qualitative Concept', 'Quantitative Concept', 'Functional Concept', and 'Spatial Concept'. Metathesaurus examples include "Civil Rights", "Freedom", "Ethics", "Spiritualism", and "Capitalism". STY: Immunologic Factor DEF: A biologic factor whose activities affect or play a role in the functioning of the immune system. Metathesaurus examples include "Autocrine Motility Factor", "Antilymphocyte Globulin", "HIV Antigens", and "Hepatitis surface antigen". STY: Indicator or Reagent DEF: A substance used in laboratory reactions, or laboratory or diagnostic tests and procedures to detect, measure, examine, or analyze other chemicals, processes, or conditions. Metathesaurus examples include "Contrast Media", "Buffers", "Affinity Labels", and "Dansyl Compounds". STY: Individual Behavior DEF: Behavior exhibited by a human or an animal that is not a direct result of interaction with other members of the species, but which may have an effect on others. Metathesaurus examples include "Assertiveness", "Self Disclosure", "Nail Biting", and "Risk-Taking". STY: Injury or Poisoning DEF: A traumatic wound, injury, or poisoning caused by an external agent or force. Metathesaurus examples include "Frostbite", "Mushroom Poisoning", "Acid burn", "Snake Bites", and "Ergotism". STY: Inorganic Chemical DEF: The general class of substances including the elements, their ionic and isotopic counterparts, and any chemical compound whose molecules are bound together ionically rather than covalently. This includes all compounds which do not contain carbon as a principal component. The children of this type in the network are 'Element or Ion', 'Isotope', and 'Inorganic Compound'. Metathesaurus examples include "Electrolytes", "Dithionite", and "Technetium Tc 99m Sulfur Colloid". STY: Inorganic Compound DEF: A single compound, generally with ionic bonding, not containing carbon as a principal component (except carbides, carbonates, cyanides, cyanates, and carbon disulfide). The bonding between elements in inorganic compounds is generally ionic. Included here are inorganic acids and salts, alloys, alkalies, and minerals. Excluded are hydrocarbons. Metathesaurus examples include "Ferrocyanide salt", "Ammonia", and "Aluminum Hydroxide". STY: Intellectual Product DEF: A conceptual entity resulting from human endeavor. Terms assigned to this type generally refer to information created by humans for some purpose. This type has one child in the network, 'Regulation or Law'. Metathesaurus examples include "Bayes Theorem", "Information Systems", and "Literature". STY: Invertebrate DEF: An animal which has no spinal column. This type has no children in the network and is assigned to all invertebrate animals. Metathesaurus examples include "Helminths", "Octopus", "Wasps", and "Protozoa". STY: Isotope DEF: A form of element having the same atomic number (i.e., the same number of protons), but differing in atomic weight or mass due to the presence of one or more additional neutrons. Included here are both stable and radioactive isotopes. Metathesaurus examples include "Radioisotopes", "Chromium Isotopes", "Cobalt Radioisotopes", "Co-58 (8)", and "Deuterium". STY: Laboratory Procedure DEF: A procedure, method, or technique used to determine the composition, quantity, or concentration of a specimen, and which is carried out in a clinical laboratory. Included here are procedures which measure the times and rates of reactions. Metathesaurus examples include "Radioimmunoassay", "Legionella titer", "Blood Protein Electrophoresis", and "Spectrophotometry". STY: Laboratory or Test Result DEF: The outcome of a specific test to measure an attribute or to determine the presence, absence, or degree of a condition. Laboratory or test results are considered inherently quantitative and, thus, are not assigned the additional type 'Quantitative Concept'. Metathesaurus examples include "Apgar Score", "Gastric acidity", "Blood Volume", and "Hypernatremia". STY: Lactam DEF: A cyclic amide, usually with 4- or 5-membered rings that may or may not be fused to other rings, as in compounds structurally related to the penicillins and cephalosporins. Metathesaurus examples include "Penicillanic Acid", "Caprolactam", "Alloxan", and "Ticarcillin". STY: Language DEF: The system of communication used by a particular nation or people. Metathesaurus examples include "Afrikaans", "Greek, Modern", "braille", and "Welsh". STY: Lipid DEF: A fat or fat-derived substance, such as fatty acids, fatty alcohols, and waxes. Included here are glyco- and phospholipids. Metathesaurus examples include "Ceroid", "Sphingolipids", "Glycerides", and "Calcifediol". STY: Machine Activity DEF: An activity carried out primarily or exclusively by machines. Metathesaurus examples include "Air Conditioning", "Equipment Failure", "Natural Language Processing", "Computer Simulation", and "Word Processing". STY: Macromolecular Structure DEF: A very large molecule whose structure contributes to the physiology of the cell. This type has one child in the network, 'Gene or Genome'. Metathesaurus examples include "Scleroproteins", "Histone H5", and "Collagen". STY: Mammal DEF: A vertebrate having a constant body temperature and characterized by the presence of hair, mammary glands and sweat glands. This type has one child in the network, 'Human'. Metathesaurus examples include "Bears", "Macaca", "Hamsters", and "Kangaroos". STY: Manufactured Object DEF: A physical object made by human beings. The children of this type in the network are 'Medical Device', and 'Research Device'. Metathesaurus examples include "Cooking and Eating Utensils", "Bookplates", "Adhesive tape", and "Car Seats". STY: Medical Device DEF: A manufactured object used primarily in the diagnosis, treatment, or prevention of physiologic or anatomic disorders. Metathesaurus examples include "Hip Prosthesis", "Oxygenators", "Syringes", and "Obstetrical Forceps". STY: Mental Process DEF: A physiologic function involving the mind or cognitive processing. Metathesaurus examples include "Avoidance Learning", "Pattern Recognition", "Anger", and "Cognition". STY: Mental or Behavioral Dysfunction DEF: A clinically significant dysfunction whose major manifestation is behavioral or psychological. These dysfunctions may have identified or presumed biological etiologies or manifestations. Metathesaurus examples include "Memory Disorders", "Agoraphobia", "Hallucinations", "Anxiety States, Neurotic", and "Cyclothymic Disorder". STY: Molecular Biology Research Technique DEF: Any of the techniques used in the study of or the directed modification of the gene complement of a living organism. Metathesaurus examples include "Genetic Engineering", "Heterozygote Detection", "Sequence Homology Determination", and "Blotting, Northern". STY: Molecular Function DEF: A physiologic function occurring at the molecular level. This type has one child in the network, 'Genetic Function'. Metathesaurus examples include "Electron Transport", "Glycolysis", and "Binding, Competitive". STY: Molecular Sequence DEF: A broad type for grouping the collected sequences of amino acids, carbohydrates, and nucleotide sequences. Descriptions of these sequences are generally reported in the published literature and/or are deposited in and maintained by databanks such as GenBank, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories. The children of this type in the network are 'Nucleotide Sequence', 'Amino Acid Sequence', and 'Carbohydrate Sequence'. STY: Natural Phenomenon or Process DEF: A phenomenon or process that occurs irrespective of the activities of human beings. This type has one child in the network, 'Biologic Function'. Metathesaurus examples include "Lightning", "Air Movements", "Sunlight", "Biological Phenomena", and "Corrosion". STY: Neuroreactive Substance or Biogenic Amine DEF: A biologic factor whose activities affect or play a role in the functioning of the nervous system. Included here are catecholamines, neuroregulators, neurophysins, etc. Metathesaurus examples include "Catecholamine", "Tryptamines", and "Neurotensin". STY: Nucleic Acid, Nucleoside, or Nucleotide DEF: A complex compound of high molecular weight occurring in living cells. These are basically of two types, ribonucleic (RNA) and deoxyribo-nucleic (DNA) acids, both of which consist of nucleotides (nucleoside phosphates linked together by phosphate bridges). Metathesaurus examples include "Adenosine", "Dibutyryl Cyclic AMP", "Deoxyadenosines", and "Nicotinamide Mononucleotide". STY: Nucleotide Sequence DEF: The sequence of purines and pyrimidines in nucleic acids and polynucleotides. Included here are nucleotide-rich regions, conserved sequence, and DNA transforming region. Metathesaurus examples include "AT Rich Region", "Base Sequence", "Direct Repeat", and "Exons". STY: Occupation or Discipline DEF: A vocation, academic discipline, or field of study, or a subpart of an occupation or discipline. If the term refers to the individuals who have the vocation, the type 'Professional or Occupational Group' is assigned. This type has one child in the network, 'Biomedical Occupation or Discipline'. Metathesaurus examples include "Anthropology", "Ecology", "Linguistics", "Air Microbiology", and "Craniology". STY: Occupational Activity DEF: An activity carried out as part of an occupation or job. The children of this type in the network are 'Health Care Activity', 'Research Activity', 'Governmental or Regulatory Activity', and 'Educational Activity'. Metathesaurus examples include "Financial Management", "Collective Bargaining", "Commerce", and "Book Classification". STY: Organ or Tissue Function DEF: A physiologic function of a particular organ, organ system, or tissue. Metathesaurus examples include "Osteogenesis", "Tooth Calcification", and "Renal Circulation". STY: Organic Chemical DEF: The general class of carbon-containing compounds, usually based on carbon chains or rings, and also containing hydrogen (hydrocarbons), with or without nitrogen, oxygen, or other elements. The bonding between elements is generally covalent. The children of this type in the network are 'Steroid', 'Eicosanoid', 'Lactam', 'Alkaloid', 'Nucleic Acid, Nucleoside, or Nucleotide', 'Organophosphorus Compound', 'Amino Acid, Peptide, or Protein', 'Carbohydrate', and 'Lipid'. Metathesaurus examples include "Busulfan", "Carotene", "Trinitrobenzene", and "Metanephrine". STY: Organism Attribute DEF: A property of the organism or its major parts. If the term refers to an attribute found only in non-humans, the Non-Human flag is assigned as well. Metathesaurus examples include "Body Weight", "Body Temperature", "Ambidexterity", and "Eye Color". STY: Organism Function DEF: A physiologic function of the organism as a whole, of multiple organ systems, or of multiple organs or tissues. This type has one child in the network, 'Mental Process'. Metathesaurus examples include "Growth", "Sleep", "Hibernation", and "Homeostasis". STY: Organism DEF: Generally, a living individual, including all plants and animals. The children of this type in the network are 'Plant', 'Fungus', 'Virus', 'Rickettsia or Chlamydia', 'Bacterium', and 'Animal'. Metathesaurus examples include "Plankton", "Homozygote", and "Radiation Chimera". STY: Organization DEF: The result of uniting for a common purpose or function. The continued existence of an organization is not dependent on any of its members, its location, or particular facility. Components or subparts of organizations are also included here. The children of this type in the network are 'Health Care Related Organization', 'Professional Society', and 'Self-help or Relief Organization'. Metathesaurus examples include "Universities", "United Nations", "United States Environmental Protection Agency", "European Economic Community", and "Labor Unions". STY: Organophosphorus Compound DEF: An organic compound containing phosphorus as a constituent. Included here are organic phosphinic, phosphonic and phosphoric acid derivatives and their thiophosphorus counterparts. Excluded are phospholipids and sugar phosphates. Metathesaurus examples include "Phosphonoacetic Acid", "Phosphoric Acid Esters", "Diphosphonates", and "Thiamine Triphosphate". STY: Pathologic Function DEF: A disordered process, activity, or state of the organism as a whole, of a body system or systems, or of multiple organs or tissues. Included here are normal responses to a negative stimulus as well as patholologic conditions or states that are less specific than a disease. Pathologic functions frequently have systemic effects. The children of this type in the network are 'Disease or Syndrome', 'Cell or Molecular Dysfunction', and 'Experimental Model of Disease'. Metathesaurus examples include "Shock", "Infarction", "Cerebral Anoxia", "Inflammation", "Anaphylaxis", and "Acid-Base Imbalance". STY: Patient or Disabled Group DEF: An individual or individuals classified according to a disability, disease, condition or treatment. Metathesaurus examples include "Amputees", "Child, Institutionalized", and "Inpatients". STY: Pharmacologic Substance DEF: A substance used in the treatment, diagnosis, prevention, or analysis of normal and abnormal body function. This includes substances that occur naturally in the body and are administered therapeutically. Metathesaurus examples include "Codeine", "Antipruritics", "Ampicillin", "Cardiovascular Agents", "Insulin", and "Ganglionic Blockaders". STY: Phenomenon or Process DEF: A process or state which occurs naturally or as a result of an activity. The children of this type in the network are 'Human-caused Phenomenon or Process', 'Natural Phenomenon or Process', and 'Injury or Poisoning'. Metathesaurus examples include "Disasters", "Famine", and "Noise". STY: Physical Object DEF: An object perceptible to the sense of vision or touch. The children of this type in the network are 'Organism', 'Anatomical Structure', 'Manufactured Object', and 'Substance'. STY: Physiologic Function DEF: A normal process, activity, or state of the body. The children of this type in the network are 'Organism Function', 'Organ or Tissue Function', 'Cell Function', and 'Molecular Function'. STY: Plant DEF: An organism having cellulose cell walls, growing by synthesis of inorganic substances, generally distinguished by the presence of chlorophyll, and lacking the power of locomotion. Plant parts are included here as well. This type has one child in the network, 'Alga'. Metathesaurus examples include "Potatoes", "Pollen", and "Vegetables". STY: Population Group DEF: An indivdual or individuals classified according to their sex, racial origin, religion, common place of living, financial or social status, or some other cultural or behavioral attribute. Metathesaurus examples include "Asian Americans", "Ethnic Groups", "Homeless Persons", and "Low-Income Population". STY: Professional Society DEF: An organization uniting those who have a common vocation or who are involved with a common field of study. Metathesaurus examples include "American Medical Association", "Library Associations", and "International Council of Nurses". STY: Professional or Occupational Group DEF: An individual or individuals classified according to their vocation. Metathesaurus examples include "Zoologist", "Physicians", "Hospital Volunteers", "Clergy", "Military Personnel", and "Demographers". STY: Prostaglandin DEF: A member of the group of physiologically active compounds derived from arachidonic acid. Members of the group play major roles in the reproductive process, smooth muscle stimulation, blood pressure levels, inflammation, etc. Included here are prostacyclins, thromboxanes, and leukotrienes. Metathesaurus examples include "Alprostadil", "Prostaglandins F", "Thromboxane A2", and "Rioprostil". STY: Qualitative Concept DEF: A concept which is an assessment of some quality, rather than a direct measurement. Metathesaurus examples include "Clinical Competence", "Quality of Health Care", "Abuse of Health Services", and "Consumer Satisfaction". STY: Quantitative Concept DEF: A concept which involves the dimensions, quantity or capacity of something using some unit of measure, or which involves the quantitative comparison of entities. Metathesaurus examples include "Metric System", "Body Height", "Age Distribution", and "Secretory Rate". STY: Regulation or Law DEF: An intellectual product resulting from legislative or regulatory activity. Metathesaurus examples include "Building Codes", "Criminal Law", "Health Planning Guidelines", and "Security Measures". STY: Reptile DEF: A cold-blooded vertebrate having an external covering of scales or horny plates. Reptiles breathe by means of lungs and are generally egg-laying. Metathesaurus examples include "Lizards", "Snakes", "Turtles", and "Iguanas". STY: Research Activity DEF: An activity carried out as part of research or experimentation. This type has one child in the network, 'Molecular Biology Research Technique'. Metathesaurus examples include "Study Design", "Animal Experimentation", "Biomedical Research", and "Cluster Analysis". STY: Research Device DEF: A manufactured object used primarily in carrying out scientific research or experimentation. Metathesaurus examples include "Questionnaires", "Atmosphere Exposure Chambers", and "Cell-Free System". STY: Rickettsia or Chlamydia DEF: An organism intermediate in size and complexity between a virus and a bacterium, and which is parasitic within the cells of insects and ticks. Included here are all the chlamydias, also called "PLT" for psittacosis- lymphogranuloma venereum-trachoma. Metathesaurus examples include "Anaplasma", "Bartonella", and "Chlamydia trachomatis". STY: Self-help or Relief Organization DEF: An organization whose purpose and function is to provide assistance to the needy or to offer support to those sharing similar problems. Metathesaurus examples include "Alcoholics Anonymous", "Red Cross", "Charities", and "Tuberculosis Societies". STY: Sign or Symptom DEF: An observable manifestation of a disease or condition based on clinical judgment, or a manifestation of a disease or condition which is experienced by the patient and reported as a subjective observation. Metathesaurus examples include "Pallor", "Body Weight Changes", "Echolalia", "Hyperventilation", "Pain", "Toothache", "Nausea", and "Cough". STY: Social Behavior DEF: Behavior that is a direct result or function of the interaction of humans or animals with their fellows. Metathesaurus examples include "Interpersonal Relations", "Social Conformity", "Acculturation", and "Communication". STY: Spatial Concept DEF: A location, region, or space, generally having definite boundaries. The children of this type in the network are 'Body Space or Junction', 'Body Location or Region', 'Molecular Sequence', and 'Geographic Area'. STY: Steroid DEF: One of a group of polycyclic, 17-carbon-atom, fused-ring compounds occurring both in natural and synthetic forms. Included here are naturally occurring and synthetic steroids, bufanolides, cardanolides, homosteroids, norsteroids, and secosteroids. Metathesaurus examples include "Bufanolides", "Norandrostanes", "17-Hydroxycorticosteroids", and "Prednisone". STY: Substance DEF: A material with definite or fairly definite chemical composition. The children of this type in the network are 'Chemical', 'Body Substance', and 'Food'. Metathesaurus examples include "Charcoal", "Foreign Bodies", "Air", "Fossils", and "Electrons". STY: Temporal Concept DEF: A concept which pertains to time or duration. Metathesaurus examples include "Half-Life", "Postoperative Period", "Puerperium", "Birth Intervals", and "Postimplantation Phase". STY: Therapeutic or Preventive Procedure DEF: A procedure, method, or technique designed to prevent a disease or a disorder, or to improve physical function, or used in the process of treating a disease or injury. Metathesaurus examples include "Cesarean Section", "Counseling", "Vaccine Therapy", and "Cochlear Implant". STY: Tissue DEF: An aggregation of similarly specialized cells and the associated intercellular substance. Tissues are relatively non-localized in comparison to body parts, organs or organ components. Metathesaurus examples include "Cartilage", "Epidermis", "Basophilic muscle fibers", and "Endothelium". STY: Vertebrate DEF: An animal which has a spinal column. The children of this type in the network are 'Amphibian', 'Bird', 'Fish', 'Reptile', and 'Mammal'. STY: Virus DEF: An organism consisting of a core of a single nucleic acid enclosed in a protective coat of protein. A virus may replicate only inside a host living cell. A virus exhibits some but not all of the usual characteristics of living things. Metathesaurus examples include "Parvoviridae", "Foot-and-Mouth Disease Virus", and "Echovirus 6". STY: Vitamin DEF: A substance, usually an organic chemical complex, present in natural products or made synthetically, which is essential in the diet of man or other higher animals. Included here are vitamin precursors and provitamins. Metathesaurus examples include "Vitamin A", "Ascorbic Acid", "Biotin", "Riboflavin", and "25-Hydroxyvitamin D 2". STY|T001|Organism|A1.1|Generally, a living individual, including all plants and animals. The children of this type in the network are 'Plant', 'Fungus', 'Virus', 'Rickettsia or Chlamydia', 'Bacterium', and 'Animal'. Metathesaurus examples include "Plankton", "Homozygote", and "Radiation Chimera".||| STY|T002|Plant|A1.1.1|An organism having cellulose cell walls, growing by synthesis of inorganic substances, generally distinguished by the presence of chlorophyll, and lacking the power of locomotion. Plant parts are included here as well. This type has one child in the network, 'Alga'. Metathesaurus examples include "Potatoes", "Pollen", and "Vegetables".||| STY|T003|Alga|A1.1.1.1|A chiefly aquatic plant that contains chlorophyll, but does not form embryos during development and lacks vascular tissue. Metathesaurus examples include "Chlorella", "Laminaria", "Seaweed", and "Anabaena".||| STY|T004|Fungus|A1.1.2|A eukaryotic organism characterized by the absence of chlorophyll and the presence of a rigid cell wall. Included here are both slime molds and true fungi such as yeasts, molds, mildews, and mushrooms. Metathesaurus examples include "Blastomyces", "Neurospora", "Aspergillus clavatus", and "Helminthosporium".||| STY|T005|Virus|A1.1.3|An organism consisting of a core of a single nucleic acid enclosed in a protective coat of protein. A virus may replicate only inside a host living cell. A virus exhibits some but not all of the usual characteristics of living things. Metathesaurus examples include "Parvoviridae", "Foot-and-Mouth Disease Virus", and "Echovirus 6".||| STY|T006|Rickettsia or Chlamydia|A1.1.4|An organism intermediate in size and complexity between a virus and a bacterium, and which is parasitic within the cells of insects and ticks. Included here are all the chlamydias, also called "PLT" for psittacosis- lymphogranuloma venereum-trachoma. Metathesaurus examples include "Anaplasma", "Bartonella", and "Chlamydia trachomatis".||| RL|T141|carries_out|CC.2|Executes a function or performs a procedure or activity. This includes transacts, operates on, handles, and executes.|CO|carried_out_by| RL|T142|interacts_with|CC.3|Acts, functions, or operates together with.|IW|interacts_with| RL|T143|practices|CC.4|Performs habitually or customarily.|PA|practiced_by| RL|T144|produces|CC.5|Brings forth, generates or creates. This includes yields, secretes, emits, biosynthesizes, generates, releases, discharges, and creates.|PS|produced_by| Activity|isa|Event|D| Amphibian|isa|Vertebrate|D| Animal|isa|Organism|D| Biologic Function|isa|Natural Phenomenon or Process|D| Body Location or Region|isa|Spatial Concept|D| Diagnostic Procedure|isa|Health Care Activity|D| Finding|associated_with|Pathologic Function|D| Group|exhibits|Behavior|D| Injury or Poisoning|complicates|Pathologic Function|D| Organism Attribute|measurement_of|Physiologic Function|D| UI: T020 STY: Acquired Abnormality STN: A1.2.3 DEF: An abnormal structure, or one that is abnormal in size or location, found in or deriving from a previously normal structure. Metathesaurus examples include "Hernia", "Fistula", "Hemorrhoids", and "Varicose Veins". HL: {isa} Anatomical Structure UI: T052 STY: Activity STN: B1 DEF: An operation or series of operations that an organism or machine carries out or participates in. The children of this type in the network are 'Behavior', 'Daily or Recreational Activity', 'Occupational Activity', and 'Machine Activity'. Metathesaurus examples include "Development Planning", "Expeditions", "Information Distribution", "Migration", and "Voting". HL: {isa} Event; {inverse_isa} Behavior; {inverse_isa} Daily or Recreational Activity; {inverse_isa} Occupational Activity; {inverse_isa} Machine Activity UI: T100 STY: Age Group STN: A2.9.4 DEF: An individual or individuals classified according to their age. Metathesaurus examples include "Adult", "Infant, Premature", "Adolescents", and "Octogenarian". HL: {isa} Group UI: T003 STY: Alga STN: A1.1.1.1 DEF: A chiefly aquatic plant that contains chlorophyll, but does not form embryos during development and lacks vascular tissue. Metathesaurus examples include "Chlorella", "Laminaria", "Seaweed", and "Anabaena". HL: {isa} Plant UI: T113 STY: Alkaloid STN: A1.4.1.2.1.4 DEF: A basic, nitrogen-containing compound of plant origin. Included here are aporphines, cinchona, curare, ergot, opium, belladonna, rauwolfia, and vinca alkaloids, among others. Metathesaurus examples include "Quinidine", "Aconitine", "3-Hydroxy-N-Methylmorphinan", "Vincamine", and "Rauwolfia Alkaloids". HL: {isa} Organic Chemical UI: T087 STY: Amino Acid Sequence STN: A2.1.5.3.2 DEF: The sequence of amino acids as arrayed in chains, sheets, etc., within the protein molecule. It is of fundamental importance in determining protein structure. HL: {isa} Molecular Sequence UI: T173 RL: adjacent_to ABR: AD RIN: adjacent_to RTN: AA.5 DEF: Close to, near or abutting another physical unit with no other structure of the same kind intervening. This includes adjoins, abuts, is contiguous to, is juxtaposed, and is close to. HL: {isa} physically_related_to STL: [Body Location or Region|Body Location or Region]; [Body Location or Region|Body Part, Organ, or Organ Component]; [Body Location or Region|Body Space or Junction]; [Body Part, Organ, or Organ Component|Body Part, Organ, or Organ Component]; [Body Part, Organ, or Organ Component|Body Space or Junction]; [Body Part, Organ, or Organ Component|Cell]; [Body Part, Organ, or Organ Component|Tissue]; [Body Space or Junction|Body Space or Junction]; [Cell Component|Body Space or Junction]; [Cell Component|Cell Component]; [Cell|Cell]; [Tissue|Body Space or Junction]; [Tissue|Tissue] UI: T141 RL: carries_out ABR: CO RIN: carried_out_by RTN: CC.2 DEF: Executes a function or performs a procedure or activity. This includes transacts, operates on, handles, and executes. HL: {isa} functionally_related_to STL: [Group|Occupational Activity]; [Group|Daily or Recreational Activity]; [Organization|Occupational Activity]; [Gene or Genome|Molecular Function] UI: T137 RL: co-occurs_with ABR: CW RIN: co-occurs_with RTN: BB.1 DEF: Occurs at the same time as, together with, or jointly. This includes is co-incident with, is concurrent with, is contemporaneous with, accompanies, coexists with, and is concomitant with. HL: {isa} temporally_related_to STL: [Finding|Finding]; [Congenital Abnormality|Acquired Abnormality]; [Congenital Abnormality|Congenital Abnormality]; [Acquired Abnormality|Acquired Abnormality]; [Acquired Abnormality|Injury or Poisoning]; [Pathologic Function|Pathologic Function]; [Pathologic Function|Acquired Abnormality]; [Pathologic Function|Congenital Abnormality]; [Pathologic Function|Injury or Poisoning]; [Physiologic Function|Physiologic Function]; [Injury or Poisoning|Injury or Poisoning] UI: T143 RL: practices ABR: PA RIN: practiced_by RTN: CC.4 DEF: Performs habitually or customarily. HL: {isa} functionally_related_to STL: [Professional or Occupational Group|Occupation or Discipline] 
