Hyaluronan polymers

Equi RA, Jumper M, Cha C, Stern R, Schwartz DM. Hyaluronan polymer size modulates intraocular pressure. J Ocul Pharmacol Ther 1997 13 289-295. 

Hyaluronan polymers Metronidazole and Evaluation of drug release [71]... 

The hyaluronan polymer isolated from animals or bacteria is identical, and since bacterial hyaluronan is not immunogenic, it is an excellent source for medical grade hyaluronan. Extracting hyaluronan from microbial fermentation broth is a relatively simple process with high yields. An additional and important advantage of microbial hyaluronan production is that microbial cells can be physiologically and/or metabolically adapted to produce hyaluronan of high MW. 

The methylated derivatives served as the basis of elegant studies in which Jeanloz and his colleagues unequivocally established the structure of hyaluronan, dermatan sulfate, and the chondroitin sulfates. They also clarified many confusing issues, including the position of the sulfate groups in these polymers. In the course of this work, they proved that dermatan sulfate contained L-iduronic acid, a sugar not known before to occur in nature. 

Four intraarticular hyaluronic acid preparations are available for treating pain associated with OA of the knee sodium hyaluronate (Hyalgan 20 mg/2 ml Supartz 25 mg/2.5 mL), hylan polymers (Synvisc 16 mg/2 mL), and hyaluronan (Orthovisc 30 mg/2 mL). Hyalgan and Supartz are administered once weekly for five injections, whereas Synvisc and Orthovisc are administered once weekly for three injections. 

Such enzymatic catalyzed polycondensations have allowed the synthesis of a number of natural polysaccharides, but has also allowed the production of nonnatural polysaccharides such as cellulose-xylan hybrids and functionalized hyaluronan, chondroitin sulfate, and chondroitin. Such work illustrates the ever-narrowing bridge between natural and synthetic polymers and polymer syntheses. 

Other carbohydrate polymers consist of repeating oligosaccharide units. Thus, in hyaluronan irnits of glucuronic acid and N-acetyl-D-glucosamine alternate (Fig. 4-11). The "O antigens" of bacterial cell coats (p. 180) contain repeating subunits made up of a "block" of four or five different sugars. In these and... 

Abstract Carbohydrates have been investigated and developed as delivery vehicles for shuttling nucleic acids into cells. In this review, we present the state of the art in carbohydrate-based polymeric vehicles for nucleic acid delivery, with the focus on the recent successes in preclinical models, both in vitro and in vivo. Polymeric scaffolds based on the natural polysaccharides chitosan, hyaluronan, pullulan, dextran, and schizophyllan each have unique properties and potential for modification, and these results are discussed with the focus on facile synthetic routes and favorable performance in biological systems. Many of these carbohydrates have been used to develop alternative types of biomaterials for nucleic acid delivery to typical polyplexes, and these novel materials are discussed. Also presented are polymeric vehicles that incorporate copolymerized carbohydrates into polymer backbones based on polyethylenimine and polylysine and their effect on transfection and biocompatibility. Unique scaffolds, such as clusters and polymers based on cyclodextrin (CD), are also discussed, with the focus on recent successes in vivo and in the clinic. These results are presented with the emphasis on the role of carbohydrate and charge on transfection. Use of carbohydrates as molecular recognition ligands for cell-type specific dehvery is also briefly... 

The molecular domain of HA encompasses a large volume of water that expands extracellular space, hydrates tissues, and in the dermis is responsible for skin moisture. It is also a major component in the edema of the inflammatory response. Hyaluronan is capable of expanding its solvent domain over 1000 times its actual polymer volume.24 Even at low concentrations, solutions of HA have very high viscosity. 

Most of the polysaccharides of interest in this text are termed glycosaminoglycans, polymers that contain an amino sugar in the repeat unit. Glycosaminoglycans that are abundant in mammalian tissues include hyaluronan, chondroitin sulfate, dermatan sulfate, keratan sulfate, and heparin-heparan sulfate (see Table 2.4). Most of these glycosaminoglycans,... 

Figure 4.2. Determination of intrinsic viscosity. Intrinsic viscosity is determined by extrapolation of the reduced specific viscosity (r sr) to zero concentration. The reduced specific viscosity is calculated by taking the difference between the flow time in a capillary for polymer in a solvent and that of the pure solvent and dividing the difference by the flow time of the pure solvent times the polymer weight concentration. Data are shown for hyaluronan for various fractions isolated from bovine vitreous.

The physical or chemical crosslinking of polymers can be also realized in water-in-oil (W/O) emulsion systems. In this case, aqueous droplets of prepolymers are stabilized by oil-soluble surfactants in a continuous oil phase. Hyaluronan-based microgels were prepared by crosslinking of carboxylic units of hyaluronan with adipic dihydrazide in aqueous droplets [19]. Chitosan-based microgels were prepared by crosslinking of chitosan chains with glutaraldehyde in aqueous droplets [20-25],... 

Research on nasal powder drug delivery has employed polymers such as starch, dextrans, polyacrylic acid derivatives (e.g., carbopol, polycarbophil), cellulose derivatives (microcrystalline cellulose, semicrystalline cellulose, hydroxypropylmethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose), chitosan, sodium alginate, hyaluronans, and polyanhydrides such as poly(methyl vinyl ether-co-maleic anhydride) (PVM/MA). Many of these polymers have already been used as excipients in pharmaceutical formulations and are often referred to as first-generation bioadhesives [38-45], In nasal dry powder a single bioadhesive polymer or a... 

Hyaluronan (hyaluronic acid, HA) is a highly anionic unbranched linear polymer containing a -GlcAfSl,4GlcNAcP 1,4-repeating unit, which plays important roles in modulating cell adhesion, signaling, and motility. Several enzymes responsible for HA synthesis, namely Hyaluronic Acid Synthases, have been cloned from bacteria and mammals (107, 108). 

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