Dextran is a complex branched glucan (polysaccharide derived from the condensation of glucose), originally derived from wine. IUPAC defines dextrans as "Branched poly-α-d-glucosides of microbial origin having glycosidic bonds predominantly C-1 → C-6". Dextran chains are of varying lengths (from 3 to 2000 kilodaltons). The polymer main chain consists of α-1,6 glycosidic linkages between glucose monomers, with branches from α-1,3 linkages. This characteristic branching distinguishes a dextran from a dextrin, which is a straight chain glucose polymer tethered by α-1,4 or α-1,6 linkages. Occurrence
Dextran was discovered by Louis Pasteur as a microbial product in wine, but mass production was only possible after the development by Allene Jeanes of a process using bacteria. Dental plaque is rich in dextrans. Dextran is a complicating contaminant in the refining of sugar because it elevates the viscosity of sucrose solutions and fouls plumbing.Dextran is now produced from sucrose by certain lactic acid bacteria of the family lactobacillus. Species include Leuconostoc mesenteroides and Streptococcus mutans. The structure of dextran produced depends not only on the family and species of the bacterium but on the strain. They are separated by fractional precipitation from protein-free extracts using ethanol. Some bacteria coproduce fructans, which can complicate isolation of the dextrans. Uses
Dextran 70 is on the WHO Model List of Essential Medicines, the most important medications needed in a health system.Medicinally it is used as an antithrombotic (antiplatelet), to reduce blood viscosity, and as a volume expander in hypovolaemia. Microsurgery
These agents are used commonly by microsurgeons to decrease vascular thrombosis.
Typically, an intramuscular injection of 50 mg per m^2 of methotrexate is given followed by close monitoring of b-hCG levels 4 and 7 days after injection. B-hCG levels should decrease by at least 15% between those two timepoints. Surgery is required for patients who have failed or have contraindications to methotrexate therapy, are experiencing significant blood loss, or have signs of ectopic rupture. Epidemiology
First trimester bleeding is more common than second or third trimester bleeding. First trimester bleeding may be associated with complications in later pregnancy, including placental abruption, smaller estimated fetal weight, stillbirth, and perinatal death. == References ==