Dextran is a complex, branched glucan (polysaccharide) made of many glucose molecules joined into chains of varying lengths (from 10 to 150 kilodaltons), used as an antithrombotic (anti-platelet), and to reduce blood viscosity. A glucan molecule is a Polysaccharide of D- Glucose monomers linked by glycosidic bonds. Polysaccharides are relatively complex Carbohydrates They are Polymers made up of many Monosaccharides joined together by Glycosidic bonds Glucose (Glc a Monosaccharide (or simple Sugar) also known as grape sugar, is an important Carbohydrate in Biology. The unified atomic mass unit ( u) or Dalton ( Da) or sometimes universal mass unit, is an unit of Mass used to express Thrombosis is the formation of a blood Clot ( Thrombus) inside a Blood vessel, obstructing the flow of Blood through the Circulatory Platelets, or Thrombocytes, are small cytoplasmic bodies derived from cells They circulate in the Blood of Mammals and are involved Viscosity is a measure of the resistance of a Fluid which is being deformed by either Shear stress or Extensional stress.

The straight chain consists of α1->6 glycosidic linkages between glucose molecules, while branches begin from α1->4 linkages (and in some cases, α1->2 and α1->3 linkages as well). In Chemistry, a glycosidic bond is a certain type of Functional group that joins a Carbohydrate (sugar molecule to another which may be another carbohydrate (For information on the numbering of carbon atoms in glucose, see the glucose article. Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny Glucose (Glc a Monosaccharide (or simple Sugar) also known as grape sugar, is an important Carbohydrate in Biology. ) Dextran is synthesized from sucrose by certain lactic-acid bacteria, the best-known being Leuconostoc mesenteroides and Streptococcus mutans. Streptococcus mutans is a Gram-positive, facultatively anaerobic Bacteria commonly found in the Human Oral cavity and is Dental plaque is rich in dextrans. Dental plaque is Biofilm (usually colorless that builds up on the Teeth. Dextran is also formed by the probiotic Lactobacillus brevis to create the crystals of tibicos, or water kefir fermented beverage with reported health benefits. Probiotics are Dietary supplements containing potentially beneficial Bacteria or Yeasts According to the currently adopted definition by FAO / Lactobacillus brevis is a species of Lactic acid bacteria. It can be found in many different environments and in fermented foods such as Tibicos, also known as tibi water kefir grains sugar kefir grains Japanese water crystals and California Bees are a culture of Bacteria and Yeast held in a

Contents 1 Uses 1.1 Microsurgery uses 1.2 Other medical uses 1.3 Laboratory uses 2 Side effects 3 External links

Uses

Microsurgery uses

These agents are used commonly by microsurgeons to decrease vascular thrombosis. Thrombosis is the formation of a blood Clot ( Thrombus) inside a Blood vessel, obstructing the flow of Blood through the Circulatory 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. Red blood cells are the most common type of Blood cell and the Vertebrate body's principal means of delivering Oxygen to the body tissues via the Blood Platelets, or Thrombocytes, are small cytoplasmic bodies derived from cells They circulate in the Blood of Mammals and are involved The endothelium is the thin layer of cells that line the interior surface of Blood vessels forming an interface between circulating Blood in the " Electronegativity " is the opposite of " Electropositivity," which describes an element's ability to donate electrons Red blood cells are the most common type of Blood cell and the Vertebrate body's principal means of delivering Oxygen to the body tissues via the Blood Platelets, or Thrombocytes, are small cytoplasmic bodies derived from cells They circulate in the Blood of Mammals and are involved Dextrans also reduce factor VIII-Ag Von Willebrand factor, thereby decreasing platelet function. Von Willebrand factor (vWF is a Blood Glycoprotein involved in Hemostasis. Clots formed after administration of dextrans are more easily lysed due to an altered thrombus structure (more evenly distributed platelets with coarser fibrin). Fibrin (also called Factor Ia) is a Protein involved in the clotting of blood By inhibiting α-2 antiplasmin, dextran serves as a plasminogen activator and therefore possesses thrombolytic features. Plasmin is an important Enzyme ( present in Blood that degrades many Blood plasma proteins most notable Fibrin clots The degradation Thrombolysis is the breakdown ( lysis) of blood clots by pharmacological means

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. In Physiology and Medicine, hypovolemia (also hypovolaemia is a state of decreased Blood volume more specifically decrease in volume of Blood plasma 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 intraarterial 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. A colloid is a type of mechanical Mixture where one substance is dispersed evenly throughout another In this family, dextran-40 (MW: 40,000 Da), has been the most popular member for anticoagulation therapy. An anticoagulant is a substance that prevents coagulation; that is it stops Blood from clotting 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.

Other medical uses

• It is used in some eye drops as a lubricant, and in certain intravenous fluids to solubilise other factors, e. Eye drops are saline -containing Drops used as a vector to administer medication in the Eye. g. iron (=iron dextran).
• Dextran in intravenous solution provides an osmotically neutral fluid that once in the body is digested by cells into glucose and free water. Intravenous therapy or IV therapy is the giving of Liquid substances directly into a Vein. 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. Blood is a specialized Bodily fluid that delivers necessary substances to the body's cells ��such as nutrients and oxygen—and transports Waste products Hyponatremia ( British: hyponatraemia) is an Electrolyte disturbance (disturbance of the salts in the blood in which the Sodium ( Natrium An electrolyte is any substance containing free Ions that behaves as an electrically conductive medium
• It also increases blood sugar levels. Blood sugar, used in a physiological context is a misnomer and misleading

Laboratory uses

Dextran is used in the osmotic stress technique for applying osmotic pressure to biological molecules. The osmotic stress technique is a method for measuring the effect of Water on biological molecules particularly Enzymes Just as the properties of molecules can depend Osmotic pressure is the hydrostatic pressure produced by a difference in concentration between solutions on the two sides of a surface such as a semipermeable membrane

It is also used in some size-exclusion chromatography matrices; an example is Sephadex'. Sephadex is a Trademark for Cross-linked Dextran Gel. It is normally manufactured in a bead form and most commonly used for Gel filtration

Dextran has also been used in bead form to aid in bioreactor applications.

Dextran has been used in immobilization in Biosensors.

Dextran preferentially binds to early endosomes; fluorescently-labelled Dextran can be used to visualize these endosomes under a fluorescent microscope. In Biology, an endosome is a membrane-bound compartment inside cells roughly 300-400 nm in diameter when fully mature

Dextran can be used as a stabilising coating to protect metal nanoparticles from oxidation and improve biocompatibility.

Side effects

Although there are relatively few side-effects associated with dextran use, these side-effects can be very serious. These include anaphylaxis, volume overload, pulmonary oedema, cerebral oedema, or platelet dysfunction. Anaphylaxis is an acute systemic (multi-system and severe Type I Hypersensitivity allergic reaction in humans and other Mammals Pulmonary Edema (American English or oedema (British English is swelling and/or fluid accumulation in the Lungs It leads to impaired gas exchange and may cause Cerebral edema (cerebral oedema in British English) is an excess accumulation of water in the intracellular and/or extracellular spaces of the Brain. An uncommon but significant complication of dextran osmotic effect is acute renal failure. Acute renal failure ( ARF) also known as acute kidney failure or acute kidney injury, is a rapid loss of Renal function due to damage to the 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. A glomerulus is a Capillary tuft surrounded by Bowman's capsule in Nephrons of the vertebrate Kidney. Patients with history of diabetes mellitus, renal insufficiency, or vascular disorders are most at risk. Diabetes mellitus (ˌdaɪəˈbiːtiːz or /ˌdaɪəˈbiːtəs/ /məˈlaɪtəs/ or /ˈmɛlətəs/ often referred to simply as diabetes ( Ancient Greek: grc Renal failure or kidney Brooks and others recommend the avoidance of dextran therapy in patients with chronic renal insufficiency and CrCl<40 cc per minute. Chronic kidney disease (CKD also known as chronic renal disease, is a progressive loss of renal function over a period of months or years

External links

• Resource on dextran properties and structure of dextran polymers
• Dextran (Drug Digest)

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