Colloids dextrans

Morales et al. report the synthesis and proton relaxivity of colloidal dextran-coated Fe-O nanoparticles approximately 50 nm in diameter with a unimodal size distribution. Kim et a/. report the synthesis and relaxation properties of starch-coated Fe-O nanoparticles 6 nm in diameter. 

Dextrans are particularly useful and are employed as a plasma substitute. A concentration of about 6% dextran (50,000-100,000 relative molecular weight) has equivalent viscosity and colloid-osmotic properties to blood plasma. Dextran can also be used as non-irritant absorbent wound dressings, an application also suited to alginate gels. 

Colloids. The overall incidence of reactions has been estimated to less than 0.22%. Gelatins and dextrans are more frequently incriminated than albumin or hetastarch. Evidence for IgE-mediated adverse reactions to gelatin has been reported. Adverse reactions to dextrans were estimated to 0.275%, when it was 0.099% for albumin and 0.058% for hydroxyethyl starch solutions, and 0.03% for gelatin solutions [22, 23]. 

Iron Dextran 5000- 7500 (complex with ferric chloride) Colloidal solution In 0.9% w/v sodium chloride injection Autoclave Deep IM non-deficiency anaemia (oral therapy ineffective or impractical) IV (slow infusion) non-deficiency anaemia (oral therapy ineffective or impractical)... 

Understanding the effects of colloid administration on circulating blood volume necessitates a review of those physiologic forces that determine fluid movement between capillaries and the interstitial space throughout the circulation (Fig. 10—5).4 Relative hydrostatic pressure between the capillary lumen and the interstitial space is one of the major determinants of net fluid flow into or out of the circulation. The other major determinant is the relative colloid osmotic pressure between the two spaces. Administration of exogenous colloids results in an increase in the intravascular colloid osmotic pressure. In the case of isosomotic colloids (5% albumin, 6% hetastarch, and dextran products), initial expansion of the intravascular space is essentially that of the volume of colloid administered. In the case of hyperoncotic solutions such as 25% albumin, fluid is pulled from the interstitial space into the vasculature... 

Generally, the major adverse effects associated with colloids are fluid overload, dilutional coagulopathy, and anaphy-lactoid/anaphylactic reactions.24,32 Although derived from pooled human plasma, there is no risk of disease transmission from commercially available albumin or PPF products since they are heated and sterilized by ultrafiltration prior to distribution.24 Because of direct effects on the coagulation system with the hydroxyethyl starch and dextran products, they should be used cautiously in hemorrhagic shock patients. This is another reason why crystalloids maybe preferred in hemorrhagic shock. Furthermore, hetastarch can result in an increase in amylase not associated with pancreatitis. As such, the adverse-effect profiles of the various fluid types should also be considered when selecting a resuscitation fluid. 

Therapeutic fluids include crystalloid and colloid solutions. The most commonly used crystalloids include normal saline, hypertonic saline, and lactated Ringer s solution. Examples of colloids include albumin, the dextrans, hetastarch, and fresh frozen plasma. 

Gronwall, A. Dextran and Its Use in Colloidal Solutions Academic Press, New York, 1957. 

Colloids are larger molecular weight solutions (more than 30,000 daltons) that have been recommended for use in conjunction with or as replacements for crystalloid solutions. Albumin is a monodisperse colloid because all of its molecules are of the same molecular weight, whereas hetastarch and dextran solutions are polydisperse compounds with molecules of varying molecular weights. 

Adverse effects of colloids are generally extensions of their pharmacologic activity (e.g., fluid overload, dilutional coagulopathy). Albumin and dex-tran may be associated with anaphylactoid reactions or anaphylaxis. Bleeding may occur in certain patients receiving hetastarch and dextran. 

Three colloids are currently employed as plasma volume expanders— the two polysaccharides, dextran and hydroxyethyl starch, as well as the polypeptide, gelatin. 

Eriksson M, Notley SM, Pelton R, Wagberg L. The role of polymer compatibility in the adhesion between surfaces saturated with modified dextrans. J Colloid Interface Sci 2007 310 312-320. 

For characterization of a GPC medium other than defined macromolecules as dextrans, polypeptides, polystyrene sulfates, or colloidal gold may be used. For these standards the eluent is ddH20. These macromolecules are suitable for molar mass determination of proteins with restrictions only. 

The challenge with parenteral iron therapy is that parenteral administration of inorganic free ferric iron produces serious dose-dependent toxicity, which severely limits the dose of that can be administered. However, when the ferric iron is formulated as a colloid containing particles with a core of iron oxyhydroxide surrounded by a core of carbohydrate, bioactive iron is released slowly from the stable colloid particles. In the USA, the three available forms of parenteral iron are iron dextran, sodium ferric gluconate complex, and iron sucrose. 

Akhtar, M., Dickinson, E. (2003). Emulsifying properties of whey protein-dextran conjugates at low pH and different salt concentrations. Colloids and Surfaces B Biointerfaces, 31, 125-132. 

Ding, P., Wolf, B., Frith, W.J., Clark, A.H., Norton, I.T., Pacek, A.W. (2002). Interfacial tension in phase-separated gelatin / dextran aqueous mixtures. Journal of Colloid and Interface Science, 253, 367-376. 

Gurov, A.N., Gurova, N.V., Leontiev, A.L., Tolstoguzov, V.B. (1988). Equilibrium and non-equilibrium complexes between bovine serum albumin and dextran sulfate I. Complexing conditions and composition of non-equilibrium complexes. Food Hydro-colloids, 2, 267-283. 

Wooster, T.J., Augustin, M.A. (2006). p-Factoglobulin-dextran Maillard conjugates their effect on interfacial thickness and emulsion stability. Journal of Colloid and Interface Science, 303, 564-572. 

The richest dietary sources of total iron are organ meats (liver and kidney), egg yolk, dried legumes, com, molasses and parsley. Liver is particularly valuable because of the high absorbability of its iron. However, only about 10% of dietary iron is absorbed. Iron deficiency anemia can be treated with soluble iron(II) compounds providing 200 mg in three or four daily divided doses. Oral iron(II) sulfate is the least expensive and is in wide use. Ascorbic acid increases the absorption efficiency of iron(II) sulfate. Parenteral administration of iron is used when oral iron is ineffective. Iron-dextran, a colloid formed from iron(III) chloride and an alkali-modified dextran, is one of several preparations available which has found extensive clinical use. It contains up to 28% Fe by weight and has a structural similarity to ferritin. Transfusion therapy may also be used in severe chronic anemia or acute hemorrhage. 

Aslan K, Lakowicz JR, Geddes CD. Tunable plasmonic glucose sensing based on the dissociation of ConA-aggregated dextran-coated gold colloids. Analytica Chimica Acta 2004, 517, 139-144. 

The colloid osmotic pressure of aqueous dextran solutions can be regulated by molecular weight and concentration of the solute [52]. Dissolved dextran in low concentrations possesses Newtonian flow characteristics [45]. The relationship between viscosity and concentration is shown in Fig. 6 for different dextran fractions [52]. The molecular weight dependence of the intrinsic viscosity can be estimated by several equations [37,46,53]. 

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