Crotalid Venoms: Venoms from snakes of the subfamily Crotalinae or pit vipers, found mostly in the Americas. They include the rattlesnake, cottonmouth, fer-de-lance, bushmaster, and American copperhead. Their venoms contain nontoxic proteins, cardio-, hemo-, cyto-, and neurotoxins, and many enzymes, especially phospholipases A. Many of the toxins have been characterized.Ancrod: An enzyme fraction from the venom of the Malayan pit viper, Agkistrodon rhodostoma. It catalyzes the hydrolysis of a number of amino acid esters and a limited proteolysis of fibrinogen. It is used clinically to produce controlled defibrination in patients requiring anticoagulant therapy. EC 3.4.21.-.Snakes: Limbless REPTILES of the suborder Serpentes.Batroxobin: A proteolytic enzyme obtained from the venom of fer-de-lance (Bothrops atrox). It is used as a plasma clotting agent for fibrinogen and for the detection of fibrinogen degradation products. The presence of heparin does not interfere with the clotting test. Hemocoagulase is a mixture containing batroxobin and factor X activator. EC 3.4.21.-.Viper Venoms: Venoms from SNAKES of the viperid family. They tend to be less toxic than elapid or hydrophid venoms and act mainly on the vascular system, interfering with coagulation and capillary membrane integrity and are highly cytotoxic. They contain large amounts of several enzymes, other factors, and some toxins.Snake Venoms: Solutions or mixtures of toxic and nontoxic substances elaborated by snake (Ophidia) salivary glands for the purpose of killing prey or disabling predators and delivered by grooved or hollow fangs. They usually contain enzymes, toxins, and other factors.Phospholipases A2: Phospholipases that hydrolyze the acyl group attached to the 2-position of PHOSPHOGLYCERIDES.Phospholipases A: Phospholipases that hydrolyze one of the acyl groups of phosphoglycerides or glycerophosphatidates.Phospholipases: A class of enzymes that catalyze the hydrolysis of phosphoglycerides or glycerophosphatidates. EC 3.1.-.Disintegrins: A family of polypeptides purified from snake venoms, which contain the arginine-glycine-aspartic acid (RGD) sequence. The RGD tripeptide binds to integrin receptors and thus competitively inhibits normal integrin-ligand interactions. Disintegrins thus block adhesive functions and act as platelet aggregation inhibitors.L-Amino Acid Oxidase: An enzyme that catalyzes the oxidative deamination of L-amino acids to KETO ACIDS with the generation of AMMONIA and HYDROGEN PEROXIDE. L-amino acid oxidase is widely distributed in and is thought to contribute to the toxicity of SNAKE VENOMS.Gnathostoma: A genus of parasitic nematodes that occurs in mammals including man. Infection in humans is either by larvae penetrating the skin or by ingestion of uncooked fish.Agkistrodon: A genus of venomous snakes of the subfamily Crotalinae. Twelve species of this genus are found in North and Central America and Asia. Agkistrodon contortrix is the copperhead, A. piscivorus, the cottonmouth. The former is named for its russet or orange-brown color, the latter for the white interior of its mouth. (Goin, Goin, and Zug, Introduction to Herpetology, 3d ed, p336; Moore, Poisonous Snakes of the World, 1980, p75)Antivenins: Antisera used to counteract poisoning by animal VENOMS, especially SNAKE VENOMS.Reptilian Proteins: Proteins obtained from species of REPTILES.Snake Bites: Bites by snakes. Bite by a venomous snake is characterized by stinging pain at the wound puncture. The venom injected at the site of the bite is capable of producing a deleterious effect on the blood or on the nervous system. (Webster's 3d ed; from Dorland, 27th ed, at snake, venomous)Poison Control Centers: Facilities which provide information concerning poisons and treatment of poisoning in emergencies.Cobra Venoms: Venoms from snakes of the genus Naja (family Elapidae). They contain many specific proteins that have cytotoxic, hemolytic, neurotoxic, and other properties. Like other elapid venoms, they are rich in enzymes. They include cobramines and cobralysins.Metalloendopeptidases: ENDOPEPTIDASES which use a metal such as ZINC in the catalytic mechanism.Amino Acid Sequence: The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared 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.Lethal Dose 50: The dose amount of poisonous or toxic substance or dose of ionizing radiation required to kill 50% of the tested population.Fibrinogen: Plasma glycoprotein clotted by thrombin, composed of a dimer of three non-identical pairs of polypeptide chains (alpha, beta, gamma) held together by disulfide bonds. Fibrinogen clotting is a sol-gel change involving complex molecular arrangements: whereas fibrinogen is cleaved by thrombin to form polypeptides A and B, the proteolytic action of other enzymes yields different fibrinogen degradation products.Sequence Homology, Amino Acid: The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.Platelet Aggregation: The attachment of PLATELETS to one another. This clumping together can be induced by a number of agents (e.g., THROMBIN; COLLAGEN) and is part of the mechanism leading to the formation of a THROMBUS.Platelet Aggregation Inhibitors: Drugs or agents which antagonize or impair any mechanism leading to blood platelet aggregation, whether during the phases of activation and shape change or following the dense-granule release reaction and stimulation of the prostaglandin-thromboxane system.Hydrolysis: The process of cleaving a chemical compound by the addition of a molecule of water.Peptides: Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are linear polypeptides that are normally synthesized on RIBOSOMES.Cloning, Molecular: The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.Electrophoresis, Polyacrylamide Gel: Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.Kinetics: The rate dynamics in chemical or physical systems.Encyclopedias as Topic: Works containing information articles on subjects in every field of knowledge, usually arranged in alphabetical order, or a similar work limited to a special field or subject. (From The ALA Glossary of Library and Information Science, 1983)Costa RicaProtein C: A vitamin-K dependent zymogen present in the blood, which, upon activation by thrombin and thrombomodulin exerts anticoagulant properties by inactivating factors Va and VIIIa at the rate-limiting steps of thrombin formation.Photography: Method of making images on a sensitized surface by exposure to light or other radiant energy.Trimeresurus: A genus of snakes of the family VIPERIDAE. About 30 species are currently recognized, found in southeast Asia and adjacent island chains. The Okinawa habu frequently enters dwellings in search of rats and mice; the Chinese habu is often found in suburban and agricultural areas. They are quite irritable. (Moore: Poisonous Snakes of the World, 1980, p136)Zoology: The study of animals - their morphology, growth, distribution, classification, and behavior.FloridaMexicoReptiles: Cold-blooded, air-breathing VERTEBRATES belonging to the class Reptilia, usually covered with external scales or bony plates.BaltimoreColubridae: The largest family of snakes, comprising five subfamilies: Colubrinae, Natricinae, Homalopsinae, Lycodontinae, and Xenodontinae. They show a great diversity of eating habits, some eating almost anything, others having a specialized diet. They can be oviparous, ovoviviparous, or viviparous. The majority of North American snakes are colubrines. Among the colubrids are king snakes, water moccasins, water snakes, and garter snakes. Some genera are poisonous. (Goin, Goin, and Zug, Introduction to Herpetology, 3d ed, pp321-29)Boidae: A family of snakes comprising the boas, anacondas, and pythons. They occupy a variety of habitats through the tropics and subtropics and are arboreal, aquatic or fossorial (burrowing). Some are oviparous, others ovoviviparous. Contrary to popular opinion, they do not crush the bones of their victims: their coils exert enough pressure to stop a prey's breathing, thus suffocating it. There are five subfamilies: Boinae, Bolyerinae, Erycinae, Pythoninae, and Tropidophiinae. (Goin, Goin, and Zug, Introduction to Herpetology, 3d ed, p315-320)Scarlet Fever: Infection with group A streptococci that is characterized by tonsillitis and pharyngitis. An erythematous rash is commonly present.Indigo Carmine: Indolesulfonic acid used as a dye in renal function testing for the detection of nitrates and chlorates, and in the testing of milk.Siberia: A region, north-central Asia, largely in Russia. It extends from the Ural Mountains to the Pacific Ocean and from the Arctic Ocean to central Kazakhstan and the borders of China and Mongolia.RussiaFar East: A geographic area of east and southeast Asia encompassing CHINA; HONG KONG; JAPAN; KOREA; MACAO; MONGOLIA; and TAIWAN.Bass: Common name for FISHES belonging to the order Perciformes and occurring in three different families.Russell's Viper: A genus of snakes of the family VIPERIDAE. It is distributed in West Pakistan, most of India, Burma, Ceylon, Thailand, southeast China, Taiwan, and a few islands of Indonesia. It hisses loudly when disturbed and strikes with great force and speed. Very prolific, it gives birth to 20-60 young. This viper is the leading cause of snakebite in India and Burma. (Moore: Poisonous Snakes of the World, 1980, p127)Nuclear Physics: The study of the characteristics, behavior, and internal structures of the atomic nucleus and its interactions with other nuclei. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Nuclear Fission: Nuclear reaction in which the nucleus of a heavy atom such as uranium or plutonium is split into two approximately equal parts by a neutron, charged particle, or photon.Sulfuric Acid Esters: Organic esters of sulfuric acid.Directories as Topic: Lists of persons or organizations, systematically arranged, usually in alphabetic or classed order, giving address, affiliations, etc., for individuals, and giving address, officers, functions, and similar data for organizations. (ALA Glossary of Library and Information Science, 1983)Nucleic Acid Conformation: The spatial arrangement of the atoms of a nucleic acid or polynucleotide that results in its characteristic 3-dimensional shape.Counterfeit Drugs: Drugs manufactured and sold with the intent to misrepresent its origin, authenticity, chemical composition, and or efficacy. Counterfeit drugs may contain inappropriate quantities of ingredients not listed on the label or package. In order to further deceive the consumer, the packaging, container, or labeling, may be inaccurate, incorrect, or fake.Fraud: Exploitation through misrepresentation of the facts or concealment of the purposes of the exploiter.