1,721,037 research outputs found
Additive effect of a novel Hyaluronic acid derivatives on synovial fluids viscoelasticity
No full textEvaluation of the additive effect of a novel Hyaluronic acid derivatives on synovial fluids viscoelastic properties
No full textIngegnerizzazione di Gel Mucoadesivi e Termosensibili per applicazioni al rilascio di farmaci per via oculare
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Rheological characterisation of vocal folds after injection augmentation in animal model
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Viscoelasticity and gelling behaviour of thermosensitive hydrogel based on PEO-PPO copolymer and mucoadhesive agents
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Effect of a Hyaluronic acid amide derivative on equine synovial fluid viscoelasticity
No full textA novel amphiphilic hyaluronic acid (HA) derivative has been obtained by the amidation of the carboxylic group of the glucuronic acid with hexadecylamine. This derivative, HYADD4®-G, is the hexadecylamide of 500-730 kDa hyaluronic acid, derived from Streptococcus equi and at 2% degree of substitution ( 2 moles hexadecylamine per 100 moles hexuronic acid) . Its viscoelastic properties at a concentration of 5 mg\ml in phosphate buffer saline, have been compared to those of solutions of native HA of the same molecular weight and in particular the changes in the viscoelastic properties of equine synovial fluid after the addition of different volumes of HYADD®4-G (viz, ratios synovial fluid:HYADD®4-G of 1:2, 1:1, 3:1, 7:1) have been evaluated. In the frequency range 0.1-10 Hz, the rheological behaviour of HYADD®4-G is typical of a weak gel. Throughout the whole frequency range, the elastic modulus G’ is higher than the viscous modulus G,” and both moduli are frequency independent. The elastic modulus is about two orders of magnitude higher than that of a comparable solution of native HA. The HYADD®4-G elastic modulus, ranges from 40 to 100 Pas, and its viscous modulus from 8-12 Pa.s The addition of HYADD4®-G to equine synovial fluid (SF) increased its viscolelasticity at all the SF:HYADD®4-G ratios tested, and after 48 hours at 37°C the viscoelasticity values are reduced by ca 50-70% . These results demonstrate that HYADD®4-G is able to integrate with SF, increasing the synovial fluid rheology, and could be an interesting new option in viscosupplement therapy of osteoarthritis, particularly considering its low degree of chemical modification from native hyaluronic acid
Rheological characterization of vocal fold after injection augmentation in a preliminary animal study
No full textThe investigation of vocal folds viscoelastic properties in an animal model (rabbit) after injection of various augmentation substances, 6 months after injection, is reported. The injected materials were: hyaluronan-based materials (Hylan B gel and Deflux®), cross-linked collagen (Zyplast®) and polytetrafluoroethylene (Teflon®). Rheological properties of the augmentation substances were also evaluated. The results from these animal experiments indicate that the viscoelastic properties of the vocal folds injected with Deflux®, Zyplast® and Hylan B gel are similar to the healthy vocal folds (non-injected samples) used as control, thus demonstrating that these materials are good candidates for further studies aimed at restoring/preserving the vibratory capacity of the vocal folds with injection treatment in glottal insufficiency
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