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Coagulation, also known as clotting, is the process by which blood changes from a liquid to a gel, forming a blood clot. It potentially results in hemostasis, the cessation of blood loss from a damaged vessel, followed by repair. The mechanism of coagulation involves activation, adhesion and aggregation of platelets, as well as deposition and maturation of fibrin.
Disseminated intravascular coagulation (DIC) is a condition in which blood clots form throughout the body, blocking small blood vessels. Symptoms may include chest pain, shortness of breath, leg pain, problems speaking, or problems moving parts of the body. As clotting factors and platelets are used up, bleeding may occur. This may include blood in the urine, blood in the stool, or bleeding into the skin. Complications may include organ failure.
Fibrin is a fibrous, non-globular protein involved in the clotting of blood. It is formed by the action of the protease thrombin on fibrinogen, which causes it to polymerize. The polymerized fibrin, together with platelets, forms a hemostatic plug or clot over a wound site.
Thrombin is a serine protease, an enzyme that, in humans, is encoded by the F2 gene. Prothrombin is proteolytically cleaved to form thrombin in the clotting process. Thrombin in turn acts as a serine protease that converts soluble fibrinogen into insoluble strands of fibrin, as well as catalyzing many other coagulation-related reactions.
Hementin is an anticoagulant protease from the salivary glands of the giant Amazon leech. Hementin is a calcium-dependent protease with a molecular weight of 80-120 kDa, and it contains 39 amino acid sequences. Hementin is present in both the anterior and posterior salivary glands, however it is mostly produced from certain cells in the anterior glands. The secretion of hementin is limited to the lumen of the proboscis, which the Amazon leech inserts into the host to suck blood. Hementin dissolves platelet-rich blood clots and lets the blood flow through the proboscis. Hementin is able to dissolve a type of blood clots that cannot be dissolved by other compounds, such as streptokinase and urokinase.
Disintegrins are a family of small proteins from viper venoms that function as potent inhibitors of both platelet aggregation and integrin-dependent cell adhesion.
Calloselasma is a monotypic genus created for a venomous pit viper species, Calloselasma rhodostoma, which is endemic to Southeast Asia from Thailand to northern Malaysia and on the island of Java. No subspecies are currently recognized.
Kallikreins are a subgroup of serine proteases, enzymes capable of cleaving peptide bonds in proteins. In humans, plasma kallikrein has no known paralogue, while tissue kallikrein-related peptidases (KLKs) encode a family of fifteen closely related serine proteases. These genes are localised to chromosome 19q13, forming the largest contiguous cluster of proteases within the human genome. Kallikreins are responsible for the coordination of various physiological functions including blood pressure, semen liquefaction and skin desquamation.
Kininogens are precursor proteins for kinins, biologically active polypeptides involved in blood coagulation, vasodilation, smooth muscle contraction, inflammatory regulation, and the regulation of the cardiovascular and renal systems.
Ancrod is a defibrinogenating agent derived from the venom of the Malayan pit viper. Defibrinogenating blood produces an anticoagulant effect. Ancrod is not approved or marketed in any country. It is a thrombin-like serine protease.
The thrombin time (TT), also known as the thrombin clotting time (TCT), is a blood test that measures the time it takes for a clot to form in the plasma of a blood sample containing anticoagulant, after an excess of thrombin has been added. It is used to diagnose blood coagulation disorders and to assess the effectiveness of fibrinolytic therapy. This test is repeated with pooled plasma from normal patients. The difference in time between the test and the 'normal' indicates an abnormality in the conversion of fibrinogen to fibrin, an insoluble protein.
Batroxobin, also known as reptilase, is a snake venom enzyme with Venombin A activity produced by Bothrops atrox and Bothrops moojeni, venomous species of pit viper found east of the Andes in South America. It is a hemotoxin which acts as a serine protease similarly to thrombin, and has been the subject of many medical studies as a replacement of thrombin. Different enzymes, isolated from different species of Bothrops, have been called batroxobin, but unless stated otherwise, this article covers the batroxobin produced by B. moojeni, as this is the most studied variety.
Venom-induced consumption coagulopathy (VICC) is a medical condition caused by the effects of some snake and caterpillar venoms on the blood. Important coagulation factors are activated by the specific serine proteases in the venom and as they become exhausted, coagulopathy develops. Symptoms are consistent with uncontrolled bleeding. Diagnosis is made using blood tests that assess clotting ability along with recent history of envenomation. Treatment generally involves pressure dressing, confirmatory blood testing, and antivenom administration.
Cerastocytin is a thrombin-like serine protease in snake venom.
Hementerin is a metalloprotease found in the saliva of a hematophagous leech, Haementeria depressa, which is responsible for the anticoagulant property of the animal's bite to prolong blood sucking from the host. It was discovered in 1955 at the Butantan Institute, in São Paulo, Brazil, by Gastão Rosenfeld and collaborators.
Venombin AB is an enzyme. This enzyme catalyses the following chemical reaction
Snake venom factor V activator is an enzyme. This enzyme catalyses the following chemical reaction
Atrolysin A is an enzyme that is one of six hemorrhagic toxins found in the venom of western diamondback rattlesnake. This endopeptidase has a length of 419 amino acid residues. The metalloproteinase disintegrin-like domain and the cysteine-rich domain of the enzyme are responsible for the enzyme's hemorrhagic effects on organisms via inhibition of platelet aggregation.
Venom in medicine is the medicinal use of venoms for therapeutic benefit in treating diseases.
The platelet plug, also known as the hemostatic plug or platelet thrombus, is an aggregation of platelets formed during early stages of hemostasis in response to one or more injuries to blood vessel walls. After platelets are recruited and begin to accumulate around the breakage, their “sticky” nature allows them to adhere to each other. This forms a platelet plug, which prevents more blood from leaving the body as well as any outside contaminants from getting in. The plug provides a temporary blockage of the break in the vasculature. As such, platelet plug formation occurs after vasoconstriction of the blood vessels but before the creation of the fibrin mesh clot, which is the more permanent solution to the injury. The result of the platelet plug formation is the coagulation of blood. It can also be referred to as primary hemostasis.
References
- ↑ Nolan C, Hall LS, Barlow GH (1976). Ancrod, the coagulating enzyme from Malayan pit viper (Agkistrodon rhodostoma) venom. Methods in Enzymology. Vol. 45. pp. 205–13. doi:10.1016/s0076-6879(76)45020-6. PMID 1011992.
- ↑ Stocker K, Barlow GH (1976). The coagulant enzyme from Bothrops atrox venom (batroxobin). Methods in Enzymology. Vol. 45. pp. 214–23. doi:10.1016/s0076-6879(76)45021-8. PMID 1011993.
- ↑ Markland FS, Kettner C, Schiffman S, Shaw E, Bajwa SS, Reddy KN, Kirakossian H, Patkos GB, Theodor I, Pirkle H (March 1982). "Kallikrein-like activity of crotalase, a snake venom enzyme that clots fibrinogen". Proceedings of the National Academy of Sciences of the United States of America. 79 (6): 1688–92. doi: 10.1073/pnas.79.6.1688 . PMC 346045 . PMID 7043462.
- ↑ Simmons G, Bundalian M, Theodor I, Martinoli J, Pirkle H (November 1985). "Action of crotalase, an enzyme with thrombin-like and kallikrein-like specificities, on tripeptide nitroanilide derivatives". Thrombosis Research. 40 (4): 555–61. doi:10.1016/0049-3848(85)90292-0. PMID 2934864.
- ↑ Itoh N, Tanaka N, Funakoshi I, Kawasaki T, Mihashi S, Yamashina I (June 1988). "Organization of the gene for batroxobin, a thrombin-like snake venom enzyme. Homology with the trypsin/kallikrein gene family". The Journal of Biological Chemistry. 263 (16): 7628–31. doi: 10.1016/S0021-9258(18)68544-8 . PMID 3163691.
- ↑ Bell WR, Jr (1997). "Defibrinogenating enzymes". Drugs. 54 (Suppl 3): 18–30, discussion 30–1. doi:10.2165/00003495-199700543-00005. PMID 9360849. S2CID 25006039.
- ↑ Kelton, JG; Smith, JW; Moffatt, D; Santos, A; Horsewood, P (1999). "The interaction of ancrod with human platelets". Platelets. 10 (1): 24–9. doi:10.1080/09537109976310. PMID 16801067.
- ↑ Hao Z, Liu M, Counsell C, Wardlaw JM, Lin S, Zhao X (March 2012). "Fibrinogen depleting agents for acute ischaemic stroke". The Cochrane Database of Systematic Reviews (3): CD000091. doi:10.1002/14651858.CD000091.pub2. PMID 22419274.
- ↑ Vu, TT; Stafford, AR; Leslie, BA; Kim, PY; Fredenburgh, JC; Weitz, JI (7 June 2013). "Batroxobin binds fibrin with higher affinity and promotes clot expansion to a greater extent than thrombin". The Journal of Biological Chemistry. 288 (23): 16862–71. doi: 10.1074/jbc.M113.464750 . PMC 3675619 . PMID 23612970.
