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At least 487 records · Page 27Linked to original sources
PubMed1996

Efficacy of adhesion barriers. Resorbable hydrogel, oxidized regenerated cellulose and hyaluronic acid.

OBJECTIVE: To compare a novel resorbable hydrogel barrier with two previously studied barriers, oxidized regenerated cellulose and hyaluronic acid, for the prevention of postoperative adhesions. STUDY DESIGN: Two models were employed in the rat uterine horn, one of adhesion formation after devascularization and serosal injury and one of adhesion reformation after adhesiolysis RESULTS: In the devascularization model, hydrogel treatment reduced the mean extent of adhesion formation from 73% in the control group to 13% (P < .005). Hyaluronic acid pretreatment reduced the extent of adhesion formation to 44% (P < .05), while oxidized regenerated cellulose failed to reduce formation (P > .25). In the adhesiolysis model, treatment with the hydrogel reduced the mean extent of adhesion formation from 87% in the control group to 20% (P < .005). Neither the oxidized regenerated cellulose nor the hyaluronic acid treatments lowered the extent of adhesion formation from the control group (P > .25). The hydrogel barrier was observed to be resorbed over a five-day period and remained adherent to the tissue during resorption. CONCLUSION: Resorbable hydrogel barriers are highly effective in the reduction of adhesion formation and reformation in the rat. This probably due to the good biocompatibility and retention of these materials upon the site of application.

Animals↗
PubMed1980

Enhanced diffusivity of glucose in a matrix of hyaluronic acid.

The diffusion coefficients for glucose and sucrose within matrices of hyaluronic acid are contrasted with coefficients determined in matrices of agarose. Diffusivity is similar in 0.5 and 1% matrices of both polysaccharide polymers dissolved in saline (0.9% NaCl solution) buffered at pH 7.4 with 0.01 M sodium phosphate. In a 2.5% matrix of hyaluronate, but not agarose, glucose diffusivity is enhanced 3-fold, whereas simultaneously determined sucrose diffusivity remains unchanged from that in the 1% matrix. The 1% hyaluronate matrix will enhance glucose diffusivity if an inorganic cationic serum constituent(s) with a molecular weight of less than 500 is incorporated into the solvent. This enhanced diffusivity is inversely dependent on glucose concentration and on the degree of polymerization of the hyaluronate in the matrix. The presence of an appropriately constituted matrix of hyaluronic acid endows the resultant fluid with several properties generally ascribed to membranes: permselectivity (even glucose and sucrose behave differently), saturability, and the potential to enhance translational movement of selected solutes such as glucose.

Animals↗
PubMedDate not supplied

Deep-fill hyaluronic acid for the temporary treatment of the naso-jugal groove: a report of 303 consecutive treatments.

PURPOSE: To report a 2-year experience of treating the naso-jugal groove with injectable hyaluronic acid gel, using a deep-fill method. METHODS: This was a consecutive, retrospective, nonrandomized case series of patients presenting with concerns involving dark circles, lower eyelid hollows, or other contour irregularities that make up the naso-jugal groove. One author performed all treatments, consisting of transcutaneous injection of hyaluronic acid gel filler, to address the naso-jugal groove. The filler was placed deep on the anterior lip of the orbital rim and molded to the desired shape. RESULTS: Between December 2003 and December 2005, 164 patients (34 male and 130 female) received hyaluronic acid gel filler in the face. Ninety-eight patients were treated just once and 66 had multiple treatment sessions. The mean dose of filler per session was 1.53 +/- 0.8 ml, with 0.84 +/- 0.38 ml divided between the two lower eyelids. The most common complication was localized swelling, followed by bruising, asymmetry, cellulitis (2 cases), and migraine (1 case). There were no cases of visual loss. CONCLUSIONS: Hyaluronic acid gel fillers have had an enormous impact on the practice of cosmetic surgery, and this series demonstrates the usefulness of these fillers for treatment of the lower eyelid and midface. The authors recommend the deep-fill method described as a reliable means of addressing the hollow created by the naso-jugal groove.

Adult↗
PubMed1985

Exogenous hyaluronic acid (Healon) accelerates the healing of experimental myringotomies.

Topical application of hyaluronic acid (Healon) onto the borders of rat tympanic membrane perforations accelerated the rate of wound healing. The closure time was roughly 60% of that of the untreated perforations. Epithelial cells fused with opposing cells slightly in advance of supporting connective tissue and thus bridged the remaining gap. It seems as if hyaluronic acid, topically applied, can serve as a supporting and orienting matrix for the proliferating squamous epithelium.

Administration, Topical↗
PubMed1978

[Use of hyaluronic acid in the therapy of varicose ulcers of the lower limbs].

Hyaluronic acid used in the management of ulcers due to chronic venous insufficiency and post-phlebitis syndromes (27 cases) proved to possess an anti-inflammatory and anti-exudative action. It also stimulated regeneration and hence epithelialisation. Comparison of healing times in this series and 35 patients who did not receive hyaluronic acid showed that this drug, in association with other remedies, serves to bring about much quicker healing.

Adult↗
PubMed1999

Retention of hyaluronic acid in alginate beads: aspects for in vitro cartilage engineering.

Alginate has been used successfully for three-dimensional chondrocyte cultures and may be important for cartilage transplant formation. However, alginate is not a natural component of the cartilage matrix. The aim of this study was (a) to supplement alginate with the extracellular matrix component hyaluronic acid; and (b) to analyze the hyaluronic acid retention in different alginate gels. Hyaluronan is assumed to improve proteoglycan retention and may be important for in vitro matrix formation, tissue turgor, and biomechanical quality. Alginate and hyaluronan were mixed with chondrocytes and polymerized as were alginate, hyaluronan, and fibrinogen. [3H]hyaluronan was used to quantitate the leakage of hyaluronan from the gel beads. After 28 days in culture, 1.2% alginate beads supplemented with 0.26% hyaluronan contained only 9% of the initial amount of hyaluronan whereas 2.4% alginate beads still contained about 55% of the initial 0.22% hyaluronan. Release of hyaluronan from the beads was significantly lower if the beads additionally contained fibrin. Alginate beads supplemented with hyaluronan or fibrin showed increased chondrocyte proliferation compared to controls. Supplemented hyaluronan greatly diffuses out of alginate gels of lower densities. It must be assumed also that most of the hyaluronan newly synthesized by chondrocytes in these cells diffuses into the surrounding culture medium. The in vitro development of a sufficiently hygroscopic cartilage ground substance therefore may be very limited. Sufficient hyaluronic acid retention can be achieved in alginate gels with concentrations above 1.2% or by addition of fibrin.

Alginates↗
PubMed2004

Sodium hyaluronate (hyaluronic acid) promotes migration of human corneal epithelial cells in vitro.

PURPOSE: Sodium hyaluronate (hyaluronic acid) is known to promote corneal epithelial wound healing in vivo and in vitro, in animal experiments. Sodium hyaluronate is the ligand for CD44, a cell surface adhesion molecule which has been found on normal human corneal epithelial cells. The purpose of this study was to investigate the effect of sodium hyaluronate on human corneal epithelial cell migration, proliferation, and CD44 receptor expression. METHODS: Human corneal epithelial cell cultures were established from 32 donor corneoscleral rims and maintained separately in three different culture conditions: (1) culture medium only, (2) sodium hyaluronate enriched (0.6 mg/ml) medium, and (3) hydroxypropylmethylcellulose enriched (2.5 mg/ml) medium. The total area of migrating epithelial cell sheets in each case was measured by planimetry on days 4, 8, 12, and 16. Cytospin preparations of cells cultured in the different culture conditions were examined immunohistochemically for proliferation and CD44 receptor expression using antibodies directed against Ki67 and CD44 respectively. RESULTS: Cells cultured in the presence of sodium hyaluronate showed significantly increased migration at days 12 and 16 (Friedmen test: p = 0.0012, day 16; p = <0.001, day 12) compared with cells cultured in the other media. There was no difference in cell proliferation (Ki67) or CD44 expression on cells cultured in the different culture conditions. CONCLUSIONS: Sodium hyaluronate promotes migration but not proliferation or CD44 expression on human corneal epithelial cells in vitro. The beneficial effect of sodium hyaluronate in corneal wound healing is likely to be related to rapid migration of cells leading to rapid wound closure. This may be facilitated by the adhesion between CD44 on the cells and hyaluronic acid, which coats the surface of the denuded cornea.

Adult↗
PubMed1976

Enhanced synthesis and extracellular accumulation of hyaluronic acid during stimulation of quiescent human fibroblasts by mouse epidermal growth factor.

The effect of mouse epidermal growth factor (mEGF) on the synthesis of glycosaminoglycans and glycoproteins by human fibroblasts has been studied. The addition of physiological concentrations (10(-9)M) of mEGF to quiescent cultures preincubated in the absence of serum was found to elicit an increased incorporation of 3H-glucosamine into the glycosaminoglycans and glycoproteins of both the cellular and extracellular fractions. Although the growth response to the factor, as measured by DNA replication, was minimal under these conditions as compared with the effect of serum, the mEGF-induced incorporation of glucosamine into these cellular constituents and into the extracellular glycoproteins was comparable to that elicited by serum shift-up. Serum, however, caused a significantly larger incorporation of glucoasimine into extracellular, acid-soluble glycosaminoglycans, which were shown to contain hyaluronic acid as the major component. As previously demonstrated, the growth response to mEGF can be enhanced several fold by an mEGF-binding arginine esterase, which is normally associated with the factor in vivo, and by ascorbate. The esterase was found to increase markedly the mEGF-induced incorporation of glucosamine into extracellular hyaluronic acid, while the addition of ascorbic acid did not significantly alter glucosamine incorporation.

Ascorbic Acid↗
PubMedDate not supplied

Elimination of hyaluronic acid from the blood stream in the human.

The removal of hyaluronic acid (HA) from the blood-stream was studied in four normal human subjects after injection of high molecular weight preparations labelled with 3H in the acetyl position. The plasma half-life of the injected material ranged between 2.5 and 5.5 min. The daily turnover of HA in the circulation was estimated to be at least 150 mg. Its elimination was predominantly extrarenal, the upper molecular weight limit for renal excretion being 25 000. Evidence for rapid degradation was provided by the identification of 3H2O in urine. Calculations from the specific activity of urinary 3H2O indicated that approximately 55% of the acetyl content of the injected HA was completely oxidized within 3 h, and 85% within the first day. It is concluded that hyaluronic acid in the amounts currently used for therapeutic purposes should not accumulate significantly in the circulation.

Adult↗
PubMed1996

Synchronized order of appearance of hyaluronic acid (or acidic galactan) --> chondroitin C-6 sulfate --> chondroitin C-4/C-6 sulfate, heparan sulfate, dermatan sulfate --> heparin during morphogenesis, differentiation and development.

The synthesis of glycosaminoglycans and acidic polysaccharides during embryonic and fetal development in mammals and molluscs is briefly reviewed. A sequential order of appearance of each of the acidic polysaccharides was observed, coinciding with the major processes of the ontogeny. In mammals, hyaluronic acid is the first glycosaminoglycan synthesized at the beginning of morphogenesis. This glycosaminoglycan is then replaced by chondroitin 6-sulfate during the migration of the mesenchymal cells. Heparan sulfate, dermatan sulfate and chondroitin 4-sulfate are synthesized only during cell differentiation. The synthesis of heparin, on the other hand, is confined to mast cells in a few tissues and is a late event in the differentiation process. The same general pattern is also observed in molluscs except that hyaluronic acid is replaced by an acidic galactan in the morphogenetic process. The activity of the degrading enzymes responsible for the disappearance of hyaluronic acid, chondroitin sulfate and the acidic galactan in each phase of embryonic development is also reviewed.

Animals↗
PubMed1989

Cigarette smoke degrades hyaluronic acid.

Cigarette smoke has been implicated in the pathogenesis of a variety of diseases that affect connective tissues. The effect of the gas phase of cigarette smoke on hyaluronic acid was investigated in vitro. The smoke markedly reduced the chain length of purified hyaluronic acid as assessed by both viscometry and gel chromatography. The hyaluronate exposed to smoke, nevertheless, could aggregate proteoglycans, although the viscosity of the aggregates was lower than in those formed with the unexposed material. The degradation of the hyaluronate was a rapid phenomenon and was inhibited by dimethylsulfoxide, a known scavenger of hydroxyl radicals. We conclude that free radicals in the gas phase of cigarette smoke degrade hyaluronic acid in vitro.

Chromatography, Gel↗
PubMed1983

Distribution of proteoglycans and hyaluronic acid in transverse sections of bovine thoracic aorta.

The distribution of hyaluronic acid and proteoglycans in bovine thoracic aorta was studied by Alcian Blue staining of frozen tissue sections under controlled electrolyte conditions with and without prior enzymic digestion. Some sections were digested with chondroitinase ABC, testicular hyaluronidase or bacterial collagenase and subsequent staining permitted conclusions to be drawn about the distribution of specific glycosaminoglycans within the tissue. The total glycosaminoglycan content was maximal in the intima and decreased across the arterial wall to the outermost adventitial layer. The content of proteoglycan containing chondroitin sulphate and/or dermatan sulphate chains paralleled this distribution. However, other glycosaminoglycans also contributed significantly to staining, although there was no evidence for any appreciable concentration of heparin or highly sulphated heparan sulphate. Several experiments indicated that proteoglycan containing chondroitin sulphate and/or dermatan sulphate was associated with elastic laminae which were often seen stained along their periphery. Hyaluronic acid was present at significant concentrations in all locations of the aorta and there was evidence for a similar distribution of heparan sulphate which was possible also present at a high concentration in the endothelium. Staining of sections after treatment with 4 M guanidinium chloride confirmed that this extractant removed most of the proteoglycan from the tissue section.

Animals↗
PubMed1994

Mucolipidosis IV fibroblasts synthesize normal amounts of hyaluronic acid.

Mucolipidosis IV (ML IV) (McKusick 252650) is an autosomal recessive metabolic disorder that displays signs of both lipid and mucopolysaccharide (glycosaminoglycan) storage. It has been reported that fibroblasts from ML IV patients exhibit abnormally high synthesis of hyaluronic acid in culture. In our search for a biochemical marker that will enable positive identification of ML IV, we studied glycosaminoglycan synthesis in fibroblast cultures from patients with this disease. ML IV and normal control fibroblasts were incubated with [3H]glucosamine and [35S]sulphate. Labelled glycosaminoglycans were extracted from the cell layer and medium. Chondroitin sulphate and hyaluronic acid were determined by analysis of disaccharides after digestion with chondroitinase ABC. Synthesis of neither of these two glycosaminoglycans differed significantly between control and ML IV fibroblasts. Synthesis of hyaluronic acid was nearly linear for 24 h, with mean calculated values of 11.7 +/- 1.4 and 14.4 +/- 1.6 pg/cell per 24 h in control and ML IV cultures respectively. The variability within the two groups is attributed primarily to population variability and possibly to culture density. These experiments exclude the possibility that a general metabolic defect in hyaluronic acid synthesis is responsible for the ML IV phenotype, nor can such a defect be used as a diagnostic tool for the disease.

Adult↗
PubMed1998

Injectable hyaluronic acid gel for soft tissue augmentation. A clinical and histological study.

BACKGROUND: Several biomaterials are available for the purpose of soft tissue augmentation, but none of them has all the properties of the ideal filler material. The recent development of hyaluronic acid gels for dermal implantation give the physician new possibilities of effective treatment in this field. OBJECTIVE: This study provides a clinical and histological evaluation of safety and efficacy of a cross-linked stabilized non-animal hyaluronic acid gel (Restylane, Q-Med, Uppsala, Sweden) to determine its characteristics, advantages, disadvantages, and side-effects. METHODS: 158 patients were treated with facial intradermal implant of hyaluronic acid gel for augmentation therapy of wrinkles and folds, and for lip augmentation and/or recontouring. The results were evaluated in all patients by subjective judgement by the physician and the patient, and by photographic method at time 0 and after 1, 2, 4 and 8 months from the procedure. In addition, a smaller histological study was carried out in five volunteer patients for a term of 52 weeks to determine the interaction and duration of the material in human healthy skin. RESULTS: Clinically, both the physicians' and patients' evaluations revealed very satisfactory results, with a global 78.5% and 73.4% respectively of moderate or marked improvement after eight months, independent of the treated area. The photographic evaluation revealed even better results with a 80.4% of moderate or marked improvement after 8 months. The safety evaluation showed a 12.5% of postoperative immediate adverse events, that were localized and transient. There was no evidence of major systemic side effects. Histologically, the product was shown to be long-lasting and well tolerated as judged by histological techniques. CONCLUSIONS: Stabilized, non-animal, hyaluronic acid gel is well tolerated and effective in augmentation therapy of soft tissues of the face. This material presents several advantages in comparison to previously used injectable biomaterials and expands the arsenal of therapeutic tools in the field of soft tissue augmentation.

Adult↗
PubMed1988

Correlated metabolism of proteoglycans and hyaluronic acid in bovine cartilage organ cultures.

Proteoglycans exist in cartilage as complexes in which many proteoglycan molecules are bound to a central filament of hyaluronic acid. Many studies have investigated changes taking place in proteoglycan monomer structure during cartilage catabolism usually under the assumption that hyaluronic acid is a relatively inert metabolic component of the complex. In this paper we present organ culture data supporting a new hypothesis that the catabolism of proteoglycans and hyaluronic acid are coordinately regulated by chondrocytes. The data indicates that: 1) newly synthesized hyaluronate and proteoglycan maintain a nearly constant ratio, almost identical to that existing for the total chemical amounts of these two components in cartilage tissue; 2) these two components are catabolized with virtually identical kinetics; and 3) this catabolic relationship in vitro reflects the loss of hyaluronate and proteoglycans from native, undissociated aggregates as isolated from the tissue. We conclude that hyaluronate catabolism is an integral part of the overall mechanism of proteoglycan resorption in cartilage and that further understanding of this process may be key to the elucidation of the regulatory pathways for proteoglycan resorption in health and disease.

Animals↗
PubMed1986

Degradation of hyaluronic acid by polymorphonuclear leukocytes.

Degradation (depolymerization) of hyaluronic acid is readily accomplished by superoxide-ion-generating systems, especially those which beget secondary free radicals. It has been presumed, but not confirmed, that this is the mechanism by which neutrophils might alter synovial fluid viscosity. We have demonstrated, in a neutrophil (PMN) superoxide system, physical disruption of the hyaluronate macromolecule using column chromatography and by measurement of intrinsic viscosity. In addition, comparison of calibrated free radical fluxes between a cell-free superoxide system and a neutrophil system revealed very close parallels in iron requirement, inhibition by free radical scavengers, and magnitude of effect. It is concluded that oxygen-derived free radicals are probably the major, if not sole, mechanism by which neutrophils might degrade hyaluronate.

Chromatography, Gel↗
PubMed1991

Interaction of a brain extracellular matrix protein with hyaluronic acid.

A glial hyaluronate-binding protein (GHAP) was isolated from bovine spinal cord and partially characterized. Bovine GHAP consisted of three immunologically related polypeptides with molecular masses of 76, 64, and 54 kDa and isoelectric points of 4.1, 4.2, and 4.4, respectively. Peptide mapping and partial amino acid sequencing showed that all three polypeptides derive from the same protein. The protein was localized immunohistochemically with rabbit antisera in the white matter surrounding the myelinated axons. Sugar analyses indicated that the three polypeptides are glycosylated and the sugar residues account for at least 30% of their weight. After enzymatic deglycosylation, the apparent molecular mass of the bovine GHAP was reduced to 43 kDa. The biochemical properties of bovine GHAP were compared to those of human GHAP. Initial peptide mapping indicated similarities between bovine and human GHAP. Partial amino acid sequencing of bovine GHAP showed a striking identity (up to 90%) with human GHAP and with the hyaluronate binding domain of the large human fibroblast proteoglycan, versican. Bovine and human GHAP were demonstrated to bind specifically to hyaluronic acid (HA) with one protein molecule binding to an average 17 disaccharide repeating units. The binding of bovine and human GHAP was inhibited by oligosaccharides of HA and specifically by the octamer. Salt concentrations of up to 1 M NaCl had very little effect on the binding of the GHAP to HA. The GHAP-HA interaction was pH dependent. Dissociation only took place at low pH (less than 3.5). Analysis of several polypeptides derived from GHAP by limited proteolysis allowed us to conclude that one of the tandem repeated sequences is sufficient for HA binding and that the aminoterminal domain (which contains an immunoglobulin-like fold) is not involved in the GHAP-HA-binding event.

Amino Acid Sequence↗