Biomedical subjects

E A Balazs

Publications and source records attributed to E A Balazs.

13 recordsLinked to original sources

PubMed1992

Effect of hylan on cartilage and chondrocyte cultures.

The protective role of hylan, a hyaluronan [hyaluronic acid (HA)] derivative, was studied in explanted bovine cartilage and isolated chondrocytes. Cartilage and chondrocytes were exposed to degradative enzymes (lysate from activated polymorphonuclear leukocytes), oxygen-derived free radicals (ODFR), conditioned media from mononuclear cells (MCCM), and interleukin-1 (IL-1), in the presence and absence of hylan. The effect of HA was also studied. In cartilage explants susceptibility to pertubation was evaluated in terms of 35S release and proteoglycan depletion and was compared to control cultures; high viscosity hylan was found to reduce 35S release in cartilage explants caused by degradative enzymes, ODFR, MCCM, and IL-1. The hylan effect was reversible and viscosity-dependent. In chondrocyte cultures, high viscosity hylan was effective in reducing cell injury caused by degradative enzymes and ODFR. The data suggest that the glycosaminoglycan hylan, as well as native HA, may mediate exposure to and/or response to stimuli associated with initiation of degenerative processes in cartilage tissues.

Animals↗

PubMed1991

Hylan gel composition for percutaneous embolization.

Viscoelastic, pseudoplastic, radiopaque injectable hylan gel for percutaneous embolization was developed and evaluated by in vitro and in vivo tests. The embolization gel is composed of cross-linked hylan (hyaluronan, hyaluronate), tantalum, microcrystalline cellulose, hexamethonium chloride, and thrombin. Upon delivery through small-lumen catheters to the appropriate vascular site, the gel induces formation of a solid blood/gel coagulum. Results from animal studies (rat aorta, rabbit auricular artery) demonstrate that formation of complete and long-lasting arterial blockage is readily achievable without complications due to blood flow, partial vessel obstruction, uncontrolled polymerization, or movement of the gel or its components (specifically thrombin and hexamethonium chloride) into the circulation. Microscopic evaluation indicates that arterial occlusion initially occurs as a result of the injected gel and formed fibrin; at 7 weeks and beyond, arteries are occluded by injected gel, inflammatory cells and fibrosis (scar tissue).

Animals↗

PubMed1991

Matrix engineering.

Matrix engineering is a technology that utilizes hyaluronan (HA, hyaluronic acid) based matrices to control, direct or augment tissue regenerative processes. Hyaluronan and the concept of matrix engineering have become established tools in ophthalmic and orthopaedic medicine. The clinical indications for HA are limited by the physical properties and short residence time of the natural HA molecule. To expand and improve upon its current medical applications, a family of HA derivatives was prepared by chemical modification and cross-linking. Relative to the non-modified HA molecule, the hylan family of polymers provides more versatile physical forms, improved mechanical properties and an extended residence time. Hylan can also be used as a surface coating to improve blood compatibility. The chemical, physical and biological properties of hylans will be reviewed, focusing on the specific therapeutic indications they enable.

Animals↗

PubMed1989

Clinical uses of hyaluronan.

The availability of elastoviscous solutions of highly purified hyaluronan has created two new therapeutic methods in human and veterinary medicine: viscosurgery and viscosupplementation. Viscosurgical tools and implants are widely used in ophthalmology and have been suggested for use in otology. Visco-supplementation of joint fluid using elastoviscous hyaluronan solutions is widely used in the treatment of equine traumatic arthritis. It was also suggested for use in idiopathic osteoarthritis in humans, but this application has not received wide acceptance. Cross-linked forms of hyaluronan have been developed and given the generic name of hylans. Water-insoluble soft gels of hylans are ideally suitable as viscosurgical implants to prevent postoperative adhesions and to control scar formation. Hylan solutions are being used in arthroscopic viscosurgery. Hylan devices in various forms (gels, tubes, membranes) have been used in animal studies for matrix engineering, the purpose of which is to control and direct tissue regeneration and augmentation.

Animals↗

PubMed1989

Preliminary studies on the use of a viscoelastic solution in arthroscopic surgery of the temporomandibular joint.

Arthroscopic surgery of the temporomandibular joint includes the potential for iatrogenic damage of intracapsular structures during introduction of instruments and manipulation of the tissues. A modification of an elastoviscous solution of crosslinked sodium hyaluronate, called hylan fluid, was used for irrigation during surgery in 55 temporomandibular joints. Forty-nine of the joints were monitored postoperatively in a study to measure safety and efficacy of the material during the arthroscopic procedure. The hylan fluid was found to be as safe as the standard irrigating fluid. The hylan fluid also significantly protected the joint surfaces and facilitated the surgical procedure.

Adult↗

PubMed1989

Morphology and ultrastructure of human vitreous fibers.

Significant alterations in vitreous structure occur with aging and disease. There is controversy as to the nature of the normal structure of the vitreous and no studies have correlated macroscopic structure with ultrastructure in the same eyes. Twenty-eight fresh, untreated human eyes were examined after removal of the sclera, choroid and retina. Dark-field slit illumination of the whole vitreous revealed the presence of macroscopic fibrous structures. The fibers had an antero-posterior orientation with anterior insertions at the vitreous base and posterior insertions in the premacular vitreous cortex. Transmission electron microscopy demonstrated the presence of collagen fibrils and no membraneous structures. Parallel collagen fibrils packed in bundles were also detected. Macroscopic vitreous fibers most likely result from alteration of the hyaluronic acid-collagen complex with aggregation of collagen fibrils into bundles as seen on electron microscopy. Identifying the mechanisms underlying this process of fiber formation could clarify the pathogenesis of vitreous liquefaction and the pathophysiology of posterior vitreous detachment.

Aged↗

PubMed1979