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Ristocetin
Ristocetin is a glycopeptide antibiotic, obtained from ''Amycolatopsis lurida'', previously used to treat staphylococcal infections. It is no longer used clinically because it caused thrombocytopenia and platelet agglutination. It is now used solely to assay those functions ''in vitro'' in the diagnosis of conditions such as von Willebrand disease (vWD) and Bernard–Soulier syndrome. Platelet agglutination caused by ristocetin can occur only in the presence of von Willebrand factor multimers, so if ristocetin is added to blood lacking the factor (or its receptor—see below), the platelets will not clump. Through an unknown mechanism, the antibiotic ristocetin causes von Willebrand factor to bind the platelet receptor glycoprotein Ib (GpIb), so when ristocetin is added to normal blood, it causes agglutination. In some types of vWD (types 2B and platelet-type), even very small amounts of ristocetin cause platelet aggregation when the patient's platelet-rich plasma is used. Thi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Von Willebrand Disease
Von Willebrand disease (VWD) is the most common hereditary blood-clotting disorder in humans. An acquired form can sometimes result from other medical conditions. It arises from a deficiency in the quality or quantity of von Willebrand factor (VWF), a multimeric protein that is required for platelet adhesion. It is known to affect several breeds of dogs as well as humans. The three forms of VWD are hereditary, acquired, and pseudo or platelet type. The three types of hereditary VWD are VWD type 1, VWD type 2, and VWD type 3. Type 2 contains various subtypes. Platelet type VWD is also an inherited condition. In 2008 a new diagnostic category of "Low VWF" was proposed to include those individuals whose von Willebrand factor levels were below the normal reference range but not low enough to be von Willebrand disease (levels in the 30-50 IU/dL range). Patients with low VWF can experience bleeding, despite mild reductions in VWF levels. VWD type 1 is the most common type of the dis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amycolatopsis
''Amycolatopsis'' is a genus of high GC-content bacteria within the family Pseudonocardiaceae. The genus is known for producing many types of antibiotics, including * Epoxyquinomicin, related to ''Amycolatopsis sulphurea'', are a class of weak antibiotic and anti-inflammatory agent. *Vancomycin, obtained from ''Amycolatopsis orientalis'', is being used for infections resistant to other antibiotics. *Ristocetin, made by ''Amycolatopsis lurida'', was an antibiotic but ceased to apply due to adverse effects of platelet agglutination. Now it is used to assay von Willebrand disease. Degradation of bio-polymers Several bacteria from the genus ''Amycolatopsis'' are able to enzymatically hydrolyze the ester bonds of poly-lactic acid (PLA) films in aquatic medium. So far, it is one of the few known bacteria able to biodegrade the bioplastic outside compost facilities in a relatively short period of time. Species ''Amycolatopsis'' comprises the following species: * '' A. acidicola'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycopeptide Antibiotic
Glycopeptide antibiotics are a class of drugs of microbial origin that are composed of glycosylated cyclic or polycyclic nonribosomal peptides. Significant glycopeptide antibiotics include the anti-infective antibiotics vancomycin, teicoplanin, telavancin, ramoplanin and decaplanin, corbomycin, complestatin and the antitumor antibiotic bleomycin. Vancomycin is used if infection with methicillin-resistant Staphylococcus aureus, methicillin-resistant ''Staphylococcus aureus'' (MRSA) is suspected. Mechanism and classification Some members of this class of drugs inhibit the synthesis of cell walls in susceptible microbes by inhibiting peptidoglycan synthesis. The core class (including vancomycin) binds to acyl-D-alanyl-D-alanine in lipid II, preventing the addition of new units to the peptidoglycan. Of this core class, one may distinguish multiple generations: the first generation includes vancomycin and teicoplanin, while the semisynthetic second generation includes lipoglycopept ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Staphylococcal Infection
A staphylococcal infection or staph infection is an infection caused by members of the '' Staphylococcus'' genus of bacteria. These bacteria commonly inhabit the skin and nose where they are innocuous, but may enter the body through cuts or abrasions which may be nearly invisible. Once inside the body, the bacteria may spread to a number of body systems and organs, including the heart, where the toxins produced by the bacteria may cause cardiac arrest. Once the bacterium has been identified as the cause of the illness, treatment is often in the form of antibiotics and, where possible, drainage of the infected area. However, many strains of this bacterium have become antibiotic resistant; for those with these kinds of infection, the body's own immune system is the only defense against the disease. If that system is weakened or compromised, the disease may progress rapidly. Anyone can contract staph, but pregnant women, children, and people with chronic diseases or who are immuno ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thrombocytopenia
Thrombocytopenia is a condition characterized by abnormally low levels of platelets, also known as thrombocytes, in the blood. It is the most common coagulation disorder among intensive care patients and is seen in a fifth of medical patients and a third of surgical patients. A normal human platelet count ranges from 150,000 to 450,000 platelets/microliter (μl) of blood. Values outside this range do not necessarily indicate disease. One common definition of thrombocytopenia requiring emergency treatment is a platelet count below 50,000/μl. Thrombocytopenia can be contrasted with the conditions associated with an abnormally ''high'' level of platelets in the blood - thrombocythemia (when the cause is unknown), and thrombocytosis (when the cause is known). Signs and symptoms Thrombocytopenia usually has no symptoms and is picked up on a routine complete blood count. Some individuals with thrombocytopenia may experience external bleeding, such as nosebleeds or bleeding gums. S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Platelet
Platelets, also called thrombocytes (from Greek θρόμβος, "clot" and κύτος, "cell"), are a component of blood whose function (along with the coagulation factors) is to react to bleeding from blood vessel injury by clumping, thereby initiating a blood clot. Platelets have no cell nucleus; they are fragments of cytoplasm that are derived from the megakaryocytes of the bone marrow or lung, which then enter the circulation. Platelets are found only in mammals, whereas in other vertebrates (e.g. birds, amphibians), thrombocytes circulate as intact mononuclear cells. One major function of platelets is to contribute to hemostasis: the process of stopping bleeding at the site of interrupted endothelium. They gather at the site and, unless the interruption is physically too large, they plug the hole. First, platelets attach to substances outside the interrupted endothelium: ''adhesion''. Second, they change shape, turn on receptors and secrete chemical messengers: ''activatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agglutination (biology)
Agglutination is the clumping of particles. The word ''agglutination'' comes from the Latin '' agglutinare'' (glueing to). Agglutination is the process that occurs if an antigen is mixed with its corresponding antibody called isoagglutinin. This term is commonly used in blood grouping. This occurs in biology in two main examples: # The clumping of cells such as bacteria or red blood cells in the presence of an antibody or complement. The antibody or other molecule binds multiple particles and joins them, creating a large complex. This increases the efficacy of microbial elimination by phagocytosis as large clumps of bacteria can be eliminated in one pass, versus the elimination of single microbial antigens. # When people are given blood transfusions of the wrong blood group, the antibodies react with the incorrectly transfused blood group and as a result, the erythrocytes clump up and stick together causing them to agglutinate. The coalescing of small particles that are suspend ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bernard–Soulier Syndrome
Bernard–Soulier syndrome (BSS) is a rare autosomal recessive bleeding disorder that is caused by a deficiency of the ''glycoprotein Ib-IX-V complex'' (GPIb-IX-V), the receptor for von Willebrand factor. The incidence of BSS is estimated to be less than 1 case per million persons, based on cases reported from Europe, North America, and Japan. BSS is a giant platelet disorder, meaning that it is characterized by abnormally large platelets. Signs and symptoms Bernard–Soulier syndrome often presents as a bleeding disorder with symptoms of: Genetics In regards to mechanism, there are three genes: GP1BA, GP1BB and GP9 that are involved (due to mutations). These mutations do not allow the GPIb-IX-V complex to bind to the von Willebrand factor, which in turn is what would help platelets adhere to a site of injury which eventually helps stop bleeding. Diagnosis In terms of diagnosis Bernard–Soulier syndrome is characterized by prolonged bleeding time, thrombocytopenia, increas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Von Willebrand Factor
Von Willebrand factor (VWF) () is a blood glycoprotein involved in hemostasis, specifically, platelet adhesion. It is deficient and/or defective in von Willebrand disease and is involved in many other diseases, including thrombotic thrombocytopenic purpura, Heyde's syndrome, and possibly hemolytic–uremic syndrome. Increased plasma levels in many cardiovascular, neoplastic, metabolic (e.g. diabetes), and connective tissue diseases are presumed to arise from adverse changes to the endothelium, and may predict an increased risk of thrombosis. Biochemistry Synthesis VWF is a large multimeric glycoprotein present in blood plasma and produced constitutively as ultra-large VWF in endothelium (in the Weibel–Palade bodies), megakaryocytes (α-granules of platelets), and subendothelial connective tissue. Structure The basic VWF monomer is a 2050-amino acid protein. Every monomer contains a number of specific domains with a specific function; elements of note are: * the D'/D3 do ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blood Plasma
Blood plasma is a light amber-colored liquid component of blood in which blood cells are absent, but contains proteins and other constituents of whole blood in suspension. It makes up about 55% of the body's total blood volume. It is the intravascular part of extracellular fluid (all body fluid outside cells). It is mostly water (up to 95% by volume), and contains important dissolved proteins (6–8%; e.g., serum albumins, globulins, and fibrinogen), glucose, clotting factors, electrolytes (, , , , , etc.), hormones, carbon dioxide (plasma being the main medium for excretory product transportation), and oxygen. It plays a vital role in an intravascular osmotic effect that keeps electrolyte concentration balanced and protects the body from infection and other blood-related disorders. Blood plasma is separated from the blood by spinning a vessel of fresh blood containing an anticoagulant in a centrifuge until the blood cells fall to the bottom of the tube. The blood plasma is t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gain Of Function
Gain-of-function research (GoF research or GoFR) is medical research that genetically alters an organism in a way that may enhance the biological functions of gene products. This may include an altered pathogenesis, transmissibility, or host range, i.e. the types of hosts that a microorganism can infect. This research is intended to reveal targets to better predict emerging infectious diseases and to develop vaccines and therapeutics. For example, influenza B can infect only humans and harbor seals. Introducing a mutation that would allow influenza B to infect rabbits in a controlled laboratory situation would be considered a gain-of-function experiment, as the virus did not previously have that function. That type of experiment could then help reveal which parts of the virus's genome correspond to the species that it can infect, enabling the creation of antiviral medicines which block this function. In virology, gain-of-function research is usually employed with the intention o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycoprotein Ib (GPIb)
Glycoprotein Ib (GPIb), also known as CD42, is a component of the GPIb-V-IX complex on platelets. The GPIb-V-IX complex binds von Willebrand factor, allowing platelet adhesion and platelet plug formation at sites of vascular injury. It is deficient in the Bernard–Soulier syndrome. A gain-of-function mutation causes platelet-type von Willebrand disease.McPherson & Pincus: ''Henry's Clinical Diagnosis and Management by Laboratory Methods'', 21st ed., pp. 760–2 (W. B. Saunders, 2006). Autoantibodies against Ib/IX can be produced in immune thrombocytopenic purpura. Components include GP1BA and GP1BB. It complexes with Glycoprotein IX Glycoprotein IX (platelet) (GP9) also known as CD42a (Cluster of Differentiation 42a), is a human gene. Platelet glycoprotein IX (GP9) is a small membrane glycoprotein found on the surface of human platelets. It forms a 1-to-1 noncovalent complex .... References External links * Glycoproteins {{protein-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
