Concentration Of Sodium Hyaluronate Research Articles

Influence of Elevated Intraocular Pressure on the Posterior Chamber–Anterior Hyaloid Membrane Barrier During Cataract Operations

To investigate the influence of elevated intraocular pressure on the posterior chamber-anterior hyaloid membrane (PC-AHM) barrier during cataract operations in ex vivo porcine eyes. A pressure transducer was connected to porcine eye anterior chambers (ACs). In experiment 1, ACs were perfused for 20 seconds with balanced salt solution containing 1.0-μm fluorescein beads (10 eyes per bottle height: 45, 85, 145, and 285 cm). In experiment 2, 5 ophthalmic viscosurgical devices with different molecular weights and sodium hyaluronate concentrations were infused into the ACs (20 eyes per ophthalmic viscosurgical device). After continuous curvilinear capsulorrhexis, hydrodissection was performed. After both experiments, PC-AHM barrier staining was evaluated through the Miyake-Apple view. Types of fluorescein staining patterns were classified as AC, zonule of Zinn, AHM, AHM tear, and ruptured capsule. In experiment 1, plateau intraocular pressure and staining type were positively correlated (Spearman rank correlation; r = 0.703, P < .001). In experiment 2, mean peak intraocular pressure was significantly greater in the ruptured capsule-type eyes than in the AC-, zonule of Zinn-, AHM (P < .001), or AHM-tear-(P = .02) type eyes, as well as in the AHM- and AHM-tear-type eyes compared with the AC and zonule of Zinn type eyes (P < .001). Intraocular pressure was significantly higher in eyes infused with ophthalmic viscosurgical devices with a higher molecular weight or sodium hyaluronate concentration (P < .05). Stress on the PC-AHM barrier increases as intraocular pressure increases. Ophthalmic viscosurgical devices with a higher molecular weight or sodium hyaluronate concentration might induce increased IOP during cataract operations. To maintain normal PC-AHM barrier function, excessive intraocular pressure should be avoided during cataract operations.

Addition of sodium hyaluronate and the effect on performance of the injectable calcium phosphate cement

An injectable calcium phosphate cement (CPC) with porous structure and excellent anti-washout ability was developed in the study. Citric acid and sodium bicarbonate were added into the CPC powder consisting of tetracalcium phosphate (TTCP) and dicalcium phosphate dihydrate (DCPD) to form macro-pores, then different concentrations of sodium hyaluronate (NaHA) solution, as liquid phase, was added into the cement to investigate its effect on CPC's performance. The prepared CPCs were tested on workability (injectable time and setting time), mechanical strength, as well as anti-washout ability. The experimental results showed that addition of NaHA not only enhanced the anti-washout ability of the CPC dramatically but also improve its other properties. When NaHA concentration was 0.6 wt%, the injectable time elongated to 15.7 +/- 0.6 min, the initial and final setting times were respectively shorten to 18.3 +/- 1.2 and 58.7 +/- 2.1 min, and the compressive strength were increased to 18.78 +/- 1.83 MPa. On the other hand, Addition of NaHA showed little effect on porous structure of the CPC and enhanced its bioactivity obviously, which was confirmed by the apatite formation on its surface after immersion in simulated body fluid (SBF). In conclusion, as an in situ shaped injectable biomaterials, the CPC with appropriate addition of NaHA would notably improve its performance and might be used in minimal invasive surgery for bone repair or reconstruction.

Novel polysaccharides-based viscoelastic formulations for ophthalmic surgery: Rheological characterization

Different formulations based on bioadhesive and biocompatible polymers, hydroxypropylmethylcellulose (HPMC), sodium hyaluronate (SH) and chitosan glutamate (CG), were prepared to be potentially used as ophthalmic viscosurgical device (OVD) during cataract surgery. Their rheological properties were analyzed in terms of flow and oscillation properties and compared to a commercially available OVD, widely employed in cataract surgery, named Viscoat. All the formulations tested presented a pseudoplastic behavior during flow. Primary systems containing HPMC or CG and HPMC/CG binary systems behaved as viscous solution (G''>G') over the range of oscillatory frequencies observed, while the primary systems containing SH and HPMC/SH binary formulations and showed an entangled network behavior when subjected to a sinusoidal stress. By increasing the SH concentration in the binary systems, the viscoelastic parameters, G'and G'', and zero frequency viscosity (derived from the Cross model) increased. Viscoat presents viscoelastic parameters values lower than the corresponding values of all the binary formulations of HPMC/SH and higher than all the formulations made up of CG and HPMC. As regard to HPMC/SH binary system, the cross-over frequency decreased by increasing SH concentration in the systems and it was the highest for Viscoat and thus the opposite occurred for the relaxation time. The rheological synergy in the binary formulations was assessed by calculating the interaction parameters which increased as a function of SH and CG concentration in the binary systems. The values of the interaction parameters of the formulations based on CG, are lower than 10 Pa indicating that they did not interact synergically while the formulations based on SH show high values of the interactions parameters (in the range from 55 to 130 Pa). This indicates that secondary bonds formation occurs between SH and HPMC. From the rheological analysis it can be concluded that the binary formulations based on CG do not possess appropriate features to be used as OVD while both the viscoelastic and the flow properties of the binary formulations made up of SH and HPMC are suitable for their application as OVD being able to maintain the ocular spaces and to be easily administrated. Moreover, thank to the adhesive properties of both components, the binary formulation should be able to interact with corneal endothelium so offering a durable protection to ocular tissue. On the basis of the rheological characterization presented in this work, we concluded that the binary system named VISC26 (HPMC at 0.8% and SH at 2.3%) represents the formulation that better fulfill the OVD requirements.

114 VITRIFICATION OF BOVINE EMBRYOS IN MEDIUM WITH POLYVINYL ALCOHOL REPLACING BSA

Embryos vitrified in medium supplemented with 4.25 μg/mL sodium hyaluronate (SH) and 0.1% polyvinyl alcohol (PVA) survived vitrification better than embryos vitrified in medium supplemented with 0.25% FAF-BSA (Walker and Seidel 2005 Reprod. Fert. Dev. 17, 153). The purpose of the present study was to determine if the small amount of SH was beneficial to in vitro survival and to examine the effects of different concentrations of PVA in vitrification solutions. Day 7 blastocysts (n = 360) were produced in vitro with semen from three bulls, two replicates each. Cryoprotectant solutions were prepared in a 2 × 3 factorial combination with two SH concentrations (0 or 4.25 μg/mL) and three PVA concentrations (0.05, 0.1%, or 0.2%). For vitrification, embryos were placed into chemically defined HEPES-buffered medium (HCDM-2) at room temperature (22–24°C) and then transferred to V1 (5 m ethylene glycol in HCDM-2) for 3 min. Next, embryos were placed in a 6 μL drop of V2 (7 m ethylene glycol, 0.5 m galactose, and 18% w/v Ficoll 70 in HCDM-2) for 45 s. During these 45 s, dilution medium (0.5 m galactose in HCDM-2) was aspirated into 0.25-mL straws, followed by the 6 μL drop of V2 plus embryos and a final short column of dilution medium. When 45 s had elapsed, the heat-sealed end of straw was dipped into liquid nitrogen to cover the embryo, and then the remainder of the straw was immersed slowly. Straws were thawed in air for 10 s and then in 37°C water for 20 s. Next, straws were shaken like a clinical thermometer four times to mix columns, and held in 37°C water for 10 min before embryos were expelled, rinsed and cultured in CDM-2 + 5% FCS. At 48 h, embryo survival (as determined by expansion of blastocysts), embryo quality (1 = excellent, 2 = fair, 3 = poor), inner cell mass (ICM) quality (1 = large and compact, 2 = clearly visible, 3 = not discernable) and blastocyst stage (5 = early, 6 = full, 7 = expanded, 8 = hatching, 9 = hatched) were evaluated and replicate averages were analyzed by ANOVA. Neither bull nor SH concentration nor PVA concentration significantly affected any response (P &gt; 0.10). Averaged over PVA concentrations, vitrification of embryos in 0 μg/mL or 4.25 μg/mL SH resulted in similar survival rates (67% vs. 62%, respectively). When averaged over SH concentrations, 0.2% PVA had a numerically higher survival rate of blastocysts as compared to 0.1% or 0.05% (71% vs. 63% and 60%, respectively). The main effects of 0 μg/mL SH and 0.2% PVA also resulted in numerically higher, but nonsignificant improvements in quality score, ICM score and blastocyst stage as compared to the other doses of SH and PVA. Vitrification of Day 7 in vitro-produced bovine blastocysts in medium containing 0.2% PVA in the absence of SH resulted in a subclass mean of 80% embryo survival. Results of this experiment show no benefit of 4.25 μg/mL SH and that 0.2% PVA may be slightly better than 0.05% or 0.1% in terms of embryo survival. Therefore, our results indicate that 0.2% PVA can be used alone as an effective alternative to animal products in this vitrification procedure for in vitro-derived bovine blastocysts.

The antiadhesive agent sodium hyaluronate increases the proliferation rate of human peritoneal mesothelial cells

Objective: Evaluating the influence of sodium hyaluronate on the proliferation rate of attached and nonattached human peritoneal mesothelial cells to elucidate whether this is a possible mechanism of action in peritoneal tissue repair. Design: Controlled laboratory experiment. Setting: A university hospital. Patient(s): Five patients undergoing colorectal surgery for noninfectious reasons. Intervention(s): Human peritoneal mesothelial cells were harvested from patients undergoing a laparotomy for noninfectious reasons. Cells, both nonattached and attached, were incubated for 4 and 24 hours with different concentrations of sodium hyaluronate. Thereafter, the cell proliferation rate was measured by XTT (2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2 H-tetrazolium-5-carboxanilide) colorimetric assay. To mimic peritoneal injury, the cells were exposed to tumor necrosis factor α and/or lipopolysaccharide and were incubated immediately or after 24 hours of exposure to 0% or 0.2% sodium hyaluronate. Afterward, the cell proliferation rate was measured. Main Outcome Measure(s): Proliferation rate measured by XTT assay. Result(s): Sodium hyaluronate significantly increased the proliferation rate of mesothelial cells, both in a nonattached ( P<.005) and attached ( P<.001) state. Exposure of the mesothelial cells to tumor necrosis factor α and/or lipopolysaccharide diminished the cells’ proliferation rate. However, incubation of these exposed cells with 0.2% sodium hyaluronate significantly increased the proliferation rate, regardless of whether the sodium hyaluronate was added immediately ( P<.001) or after 24 hours ( P<.001). Conclusion(s): Sodium hyaluronate increases the proliferation rate of human peritoneal mesothelial cells, both attached and nonattached, under normal conditions and after stimulation with tumor necrosis factor α and/or lipopolysaccharide.

Viscoelastic materials in veterinary ophthalmology

Viscoelastic materials have applications in both human and veterinary ophthalmology and orthopedics and for humans in otorhinolaryngology, urinary incontinence, cosmetic surgery and cosmetics. In ophthalmology, viscoelasties are most commonly used in facilitating cataract and other anterior segment surgeries, but also have applications in posterior segment surgery and in the topical management of keratoconjunctivitis sicca. Viscoelastics are routinely used during anterior segment surgery in filling and maintaining the anterior chamber, repositioning the iris, and to coat and protect the corneal endothelium, and expand the capsular bag prior to intraocular lens implantation. Viscoelastics can also be essential in the management of intraoperative complications such as miosis, hemorrhage, posterior capsular tears, and vitreous presentation. The most common products available for ophthalmic use include various concentrations of sodium hyaluronate, chondroitin sulfate, and hydroxypropylmethylcellulose. The physical properties of each viscoelastic material are dependent on chain length, and intra-and interchain interactions. The rheologic properties of viscosity, pseudoplasticity, viscoelasticity, and surface tension dictate the usefulness of each material for a specific purpose.

Accumulation of milky fluid: a late complication of cataract surgery

We describe 3 patients who presented with an accumulation of homogeneous milky fluid in the capsular bag several years after continuous curvilinear capsulorhexis, phacoemulsification, and posterior chamber intraocular lens (IOL) implantation. In each case, the entire edge of the anterior capsule opening was tightly attached to the peripheral IOL optic. The milky fluid was present in the closed chamber between the IOL optic and the posterior capsule. The fluid was sampled in 2 patients, and its concentration of sodium hyaluronate was determined by high-performance liquid chromatography. The concentration of sodium hyaluronate resembled that in normal aqueous humor. In 1 case, the protein concentration was measured and found to be elevated. Electrophoresis showed that human serum albumin was the main protein constituent. While the outcome was favorable in all 3 patients, this delayed complication of cataract surgery merits further study to clarify its etiology and pathogenesis.

Relationship between postoperative intraocular pressure elevation and residual sodium hyaluronate following phacoemulsification and aspiration

Purpose: To investigate the relationship between postoperative intraocular pressure (IOP) elevation and the amount and viscosity of sodium hyaluronate remaining in the anterior chamber after phacoemulsification and aspiration (PEA).Setting: Hachioji Medical Center and Tokyo Medical College Hospital, Tokyo, Japan.Methods: In 107 eyes, washout (irrigation and aspiration [I/A]) of sodium hyaluronate was performed for randomly assigned durations of 5, 10, or 20 seconds following PEA and intraocular lens (IOL) implantation. At the conclusion of washout, the flow from the I/A tip was reversed and a sample of the irrigating solution obtained from the anterior chamber. The residual sodium hyaluronate concentration was measured by sandwich assay. The kinematic viscosity of the sample was calculated from a regression equation derived from measured viscosities of standard hyaluronate solutions of various concentrations.Results: The preoperative mean IOP in the groups that received 5-, 10-, and 20-second washout was 11.9, 10.9, and 11.6 mm Hg, respectively. The mean IOP on the first postoperative day in the 5-second group was significantly higher (P = .001, Kruskal-Wallis test) than those in the 10- and 20-second groups (10.8 and 11.6 mm Hg, respectively). A significant correlation was observed between residual hyaluronate concentration and IOP on the first postoperative day (Spearman's rank correlation coefficient 0.319, n = 80, P = .045) and also between kinematic viscosity and IOP on the first postoperative day (one-factor analysis of variance, P < .001).Conclusion: The sod ium-hyaluronate-induced IOP elevation is related to its viscosity as well as to its high molecular weight. Washout times of at least 10 seconds are desirable to prevent IOP elevation.

Effects of Electric Field on Lubricating Ability of Sodium Hyaluronate Solution.

The effects of an electric field on lubricating ability of sodium hyaluronate solution was examined using a reciprocating friction tester for a sliding pair of a conductive silicone rubber cylindrical surface and a stainless steel plate. Lubricants were water or saline solutions with different concentrations of sodium hyaluronate (HA). Remarked decrease in friction was observed with externally applied low-frequency alternating current (AC3V, f=10 Hz, sinusoidal wave) in comparison with high-frequency alternating current. The changes in tangential force showed that the externally rapplied voltage in the mixed lubrication region was capable of shifting the lubrication mode to a milder condition. Under the same applied voltage condition, water-solution lubricants were more sensitive to an electric field than saline-solution lubricants. These results suggest that adsorption to friction surfaces and movement of HA dissociated in a lubricant between surfaces appear to be controlled by an electric field.

Relative molecular weight and concentration determination of sodium hyaluronate solutions by gel-exclusion high-performance liquid chromatography

Gel-exclusion chromatography coupled with HPLC instrumentation can be used to determine the molecular weight of highly purified sodium hyaluronate in solution. The method is very reproducible, precise, and rapid, and allows molecular weight determinations up to 2 million to be done in the presence of considerable impurities. This technique offers considerable advantages over traditional light-scattering, sedimentation equilibrium, and viscometry methods for molecular weight determinations, in that HPLC-gel exclusion is rapid and not subject to errors arising from impurities. Simultaneous with molecular weight measurements, sodium hyaluronate concentrations can be determined with a lower range of 0.1 to 0.3 mg/ml dependent upon the sensitivity of the refractive index-detecting system. Unlike the carbazole reaction, this technique is unaffected by low-molecular-weight impurities such as monosaccharides or substances with relative molecular weights less than 18,000.

Concentration of sodium hyaluronate in serum.

A radioassay for sodium hyaluronate using high-affinity binding protein from bovine cartilage has been modified for serum analysis. The accuracy of the method was checked by isotope dilution experiments and by recovery studies with exogenous hyaluronate. The between-assay standard deviation in the determination is 15-20%. The concentration of sodium hyaluronate in healthy adults (blood donors) is in the range of 10 to 100 micrograms/l with a mean value in the order of 30 to 40 micrograms/l. This is a lower concentration than previously reported. The same level was found in young people. Higher hyaluronate concentrations were noted in persons above 50 years of age. Analysis of plasma showed a slightly higher average hyaluronate level (5%) than in serum from the same persons. There were no notable sex differences. Analysis of serum and plasma from adult animals (rat, rabbit, dog, pig, goat, sheep, cow and horse) gave hyaluronate concentrations of the same order or higher than in human serum.

Biochemical studies on the use of sodium hyaluronate in the anterior eye segment. I. Variation of protein and ascorbic acid concentration in rabbit aqueous humor.

To investigate the safety of the use of sodium hyaluronate in anterior segment surgery, the changes in protein, ascorbic acid and hyaluronate concentration in the aqueous humor, and intraocular pressure were followed after sodium hyaluronate was injected into the anterior chamber. When a 1% solution of sodium hyaluronate with a molecular weight of 800K was injected, the recovery patterns of protein and ascorbic acid concentration to normal levels were the same as the recovery patterns after injection of phosphate buffered saline which was the solvent for sodium hyaluronate. However, when a 1% solution of sodium hyaluronate with a molecular weight of 1640K or a 2% solution with a molecular weight of 800K was injected, it was observed that the recovery times of protein and ascorbic acid concentration to normal levels were longer than that required after injection of 1%, 800K sodium hyaluronate. Further, the recovery time of the aqueous humor components to normal levels was associated with the clearance time of sodium hyaluronate from the anterior chamber. The transient increase in intraocular pressure by injection of sodium hyaluronate was observed, but it disappeared in 12 hrs. The recovery time of intraocular pressure to normal level was independent of molecular weight and concentration of sodium hyaluronate tested.

The concentration of hyaluronate in amniotic fluid

The concentration of sodium hyaluronate has been determined in amniotic fluid by a specific radioassay. It shows a large individual variation. The mean concentration is approximately 20 μg/ml at Weeks 16–20 of the gestational period. it drops to approximately 1 μg/ml at Week 30 and is then constant until the end of the pregnancy.

Hyaluronate in aqueous humour

The sodium hyaluronate concentration of aqueous humour has been determined in 10–200 μl samples by a specific radioassay. The accuracy of the technique was studied on pooled bovine aqueous humour. Analyses of untreated samples, dialysed samples and samples digested with papain and then dialysed all gave the same results within the error of the method. The mean concentration determined in 22 assays was 4·4±0·2 μg/ml while independent chemical analysis of the cetylpyridinium precipitable material gave a hexuronate content corresponding to 3·9 μg/ml of sodium hyaluronate. Hyaluronidase treatment removed the material reacting in the assay. Addition of exogenous hyaluronate to the aqueous humour could be determined quantitatively. It was concluded that determinations performed on untreated aqueous humour gave valid values of the hyaluronate content in the fluid. The concentration of hyaluronate in bovine aqueous humour increased after death presumably due to a release of hyaluronate from neighbouring tissues. The concentration of hyaluronate in fresh aqueous humour from single eyes (in a few experiments pooled material) was studied in man, cattle, sheep, pig, rabbit, opossum, rat, chicken and mutton bird. Considerable species variation was found (between 0·2 and 4·0 μg/ml). The level in man was found to be 1·1±0·1 μg/ml. Analysis of material from bovine foetuses showed lower levels than in adult animals.