Dextran is a complex branched polysaccharide made of many glucose molecules joined into chains of varying lengths. The straight chain consists of α1->6 glycosidic linkages between glucose molecules, while branches begin from α1->3 linkages (and in some cases, α1->2 and α1->4 linkages as well). (For information on the numbering of carbon atoms in glucose, see the glucose article.) Dextran is synthesized from sucrose by Leuconostoc mesenteroides streptococcus, and are also produced by bacteria and yeast. Dental plaque is rich in dextrans. Polysaccharides (sometimes called glycans) are relatively complex carbohydrates. ... Glucose (Glc), a monosaccharide, is one of the most important carbohydrates. ... A glycosidic bond is the linkage between two monosaccharides, that forms disaccharides and/or polysaccharides. ... General Name, Symbol, Number carbon, C, 6 Chemical series nonmetals Group, Period, Block 14, 2, p Appearance black (graphite) colorless (diamond) Atomic mass 12. ... Properties An atom (Greek άτομον from ά: non and τομον: divisible) is a submicroscopic structure found in all ordinary matter. ... Glucose (Glc), a monosaccharide, is one of the most important carbohydrates. ... Dental plaque is a yellowish biofilm that builds up on the teeth. ...

Uses

Microsurgery uses

These agents are used commonly by microsurgeons to decrease vascular thrombosis. The antithrombotic effect of dextran is mediated through its binding of erythrocytes, platelets, and vascular endothelium, increasing their electronegativity and thus reducing erythrocyte aggregation and platelet adhesiveness. Dextrans also reduce factor VIII-Ag Von Willebrand factor, thereby decreasing platelet function. Clots formed after administration of dextrans are more easily lysed due to an altered thrombus structure (more evenly distributed platelets with coarser fibrin). By inhibiting α-2 antiplasmin, dextran serves as a plasminogen activator and therefore possesses thrombolytic features. Outside from these features, larger dextrans, which do not pass out of the vessels, are potent osmotic agents, and thus have been used urgently to treat hypovolemia. The hemodilution caused by volume expansion with dextran use improves blood flow, thus further improving patency of microanastomoses and reducing thrombosis. Still, no difference has been detected in antithrombotic effectiveness in comparison of intraaterial and intravenous administration of dextran. Dextrans are available in multiple molecular weights ranging from 10,000 Da to 150,000 Da. The larger dextrans are excreted poorly from the kidney and therefore remain in the blood for as long as weeks until they are metabolized. Subsequently, they have prolonged antithrombotic and colloidal effects. In this family, dextran-40 (MW: 40,000 Da), has been the most popular member for anticoagulation therapy. Close to 70% of dextran-40 is excreted in urine within the first 24 hours after intravenous infusion while the remaining 30% will be retained for several more days. Although there are relatively few side-effects associated with dextran use, these side-effects can be very serious. These include anaphylaxis, volume overload, pulmonary edema, cerebral edema, or platelet dysfunction. An uncommon but significant complication of dextran osmotic effect is acute renal failure. The pathogenesis of this renal failure is the subject of many debates with direct toxic effect on tubules and glomerulus versus intraluminal hyperviscosity being some of the proposed mechanisms. Patients with history of diabetes mellitus, renal insufficiency, or vascular disorders are most at risk. Brooks and others recommend the avoidance of dextran therapy in patients with chronic renal insufficiency and CrCl<40 cc per minute. Thrombosis is the formation of a clot or thrombus inside a blood vessel, obstructing the flow of blood through the circulatory system. ... Human red blood cells Red blood cells are the most common type of blood cell and are the vertebrate bodys principal means of delivering oxygen to body tissues via the blood. ... A 250 ml bag of newly collected platelets. ... The endothelium is the layer of thin, flat cells that lines the interior surface of blood vessels, forming an interface between circulating blood in the lumen and the rest of the vessel wall. ... Electronegativity is a measure of the ability of an atom or molecule to attract electrons in the context of a chemical bond. ... Human red blood cells Red blood cells are the most common type of blood cell and are the vertebrate bodys principal means of delivering oxygen to body tissues via the blood. ... A 250 ml bag of newly collected platelets. ... Von Willebrand factor is a blood glycoprotein of the coagulation system. ... Fibrin is a protein involved in the clotting of blood. ... Plasmin is an important degrading enzyme (EC 3. ... Thrombolysis is the breakdown (lysis) by pharmacological means, of blood clots. ... In physiology and medicine, hypovolemia is a state of decreased blood volume; more specifically, decrease in volume of blood plasma. ... A colloid or colloidal dispersion, is a form of matter intermediate between a true solution and a mixture (suspension). ... Anaphylaxis is a severe and rapid systemic allergic reaction to a trigger substance, called an allergen. ... Pulmonary edema is swelling and/or fluid accumulation in the lungs. ... Cerebral edema is swelling of the brain which can occur as the result of a head injury, cardiac arrest or from the lack of proper altitude acclimatization. ... Glomerulus refers to two unrelated structures in the body, both named for their globular form. ... For the disease characterised by excretion of large amounts of severely diluted urine, see diabetes insipidus. ... Renal failure is when the kidneys fail to function properly. ...

Other medical uses

It is used in some eye drops as a lubricant, and in certain intravenous fluids. Dextran in intravenous solution provides an osmotically neutral fluid that once in the body is digested by cells into glucose and free water. It is occasionally used to replace lost blood in emergency situations, when replacement blood is not available, but must be used with caution as it does not provide necessary electrolytes and can cause hyponatremia or other electrolyte disturbances. It also increases blood sugar levels. [1] Eye drops are saline-containing drops used as a vector to administer medication in the eye. ... Red blood cells (erythrocytes) are present in the blood and help carry oxygen to the rest of the cells in the body Blood is a circulating tissue composed of fluid plasma and cells (red blood cells, white blood cells, platelets). ... The electrolyte disturbance hyponatremia exists when the sodium level in the plasma falls below 135 mmol/l. ... An electrolyte is a substance that dissociates into free ions when dissolved (or molten), to produce an electrically conductive medium. ...

Laboratory uses

Dextran is used in the osmotic stress technique for applying osmotic pressure to biological molecules. Osmotic pressure or turgor (also called turgor pressure) is the pressure produced by a solution in a space that is enclosed by a differentially permeable membrane. ...

It is also used in some size-exclusion chromatography matrices; an example is Sephadex(R). Sephadex is a Trade-name for cross-linked dextran gel. ...