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Molecular and Rheological Characterization of Hyaluronic Acid and Equine Synovial Fluid for the Treatment of Lameness in

Molecular and Rheological Characterization of Hyaluronic Acid and Equine Synovial Fluid for the Treatment of Lameness in Horses. Sara Tracy Advisors: Dr. Skip Rochefort PhD and *Dr. Jill Parker DVM Danielle Leiske Dept. of Chemical Engineering and *College of Veterinary Medicine

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Molecular and Rheological Characterization of Hyaluronic Acid and Equine Synovial Fluid for the Treatment of Lameness in

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  1. Molecular and Rheological Characterization of Hyaluronic Acid and Equine Synovial Fluid for the Treatment of Lameness in Horses Sara Tracy Advisors:Dr. Skip Rochefort PhD and *Dr. Jill Parker DVM Danielle Leiske Dept. of Chemical Engineering and *College of Veterinary Medicine Oregon State University Corvallis, Oregon

  2. Objective • Establish normal properties of equine synovial fluid • Compare to properties of hyaluronic acid solutions of various concentrations

  3. Motivation • The horse industry loses around 1 billion dollars annually due to lameness. • Lameness: An indication of a structural or functional disorder in one or more limbs that is evident during movement or in the standing position. • Hyaluronic acid is used to treat joint problems in both horses and humans.

  4. Background Synovial Fluid • Multipurpose fluid surrounding all articular joints • Synovial fluid has both viscous and elastic properties (viscoelastic) • Viscosity relates to lubrication • Elasticity relates to shock absorption

  5. Background Hyaluronic Acid (HA) • High molecular weight biopolyelectrolyte made up of repeating glucuronic acid and N-acetylglucosamine subunits • Major component of synovial fluid • Exhibits viscoelastic properties • Commonly obtained from: • Chicken combs • Human umbilical cords • Bacterial fermentation processes • Molecular weight around • 0.5 to 10 million Da

  6. Joints • Joints of focus

  7. Joints • Skeletal view of the joints

  8. Joints • Common problems with equine joints: • Degenerative Joint Disease – DJD • Damage to the articular cartilage • Commonly affects heavily worked and aged horses • Osteochondritis Dissecans – OCD • Failure of the bone underlying the smooth articular cartilage to form properly • Commonly affects young horses

  9. Synovial Fluid Average HA concentration 0.5 to 5.0 mg/mL Average molecular weight 2 to 10 million Da Viscosity at a shear rate of 0.1/second 0.1 to 1.0 Poise Hyaluronic Acid Joint Supplementation Intra-articular injection Intravenous injection Oral administration Synthovial 7/Hyalun Molecular weight - around 1.5 million Da Concentration – 3 to 5 mg/mL Joints

  10. Tests Rheology • The rheometer measures both ELASTICITY and VISCOSITY • Steady shear test measures the viscosity as a function of shear rate • Dynamic oscillatory shear test measures the viscous modulus and elastic modulus as a function of frequency Rheometrics RFS II

  11. Tests Steady Shear Test • Plate rotates at increasing shear rates • Torque, or shear stress, is measured by the rheometer • Viscosity = shear stress shearrate

  12. Tests • Bottom plate rotates at increasing shear rates • Shear stress is measured on the top cone • Viscosity decreases with increasing shear rates due to molecular disentanglement

  13. Tests Dynamic Oscillatory Shear Test • Plate oscillates at increasing frequencies • Strain and stress are measured to determine G’ and G’’ • G’ represents the elastic (storage) modulus • G’’ represents the viscous (loss) modulus • When G’ > G’’ the fluid behaves more elastic • When G’ < G’’ the fluid behaves more viscous

  14. strain = imposed stress = measured G’ (elastic modulus) = in phase G’’ (viscous modulus) = out of phase Tests

  15. Tests Capillary Viscometry • Known dilutions of the fluid are used and the flow times are measured • The flow times are used to measure relative viscosity • Relative viscosity = solution flow time solvent flow time

  16. Conclusion • Different joints have different rheological properties, which could mean different HA concentrations • Synovial fluid obtained from the hock joint behaves like a 1 to 2 mg/mL HA solution, and stifle joint fluid behaves like a 2 to 3 mg/mL HA solution

  17. Future Work • Perform light scattering to determine the specific concentration and molecular weight of HA in synovial fluid samples • Study the effectiveness of different forms of administering HA • Explore the effects of varying molecular weights and concentrations of HA supplements on an equine test group

  18. Howard Hughes Medical Institute URISC Dr. Skip Rochefort, OSU ChE Dept Dr. Jill Parker, OSU College of Veterinary Medicine Danielle Leiske and Erica Zaworski Dr. Kevin Ahern Acknowledgements

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