In vivo Mechanical Properties

Krouskop et al [5, 8] applied Doppler ultrasound techniques to measure the point-to-point biomechanical property of the human skin and subcutaneous musculatures. Tests of the forearms and legs suggested that the elastic moduli are strongly dependent on the contraction status of the muscles. A 16-fold increase (from 6.2 kPa to 109 kPa) in the modulus 

Handbook of Biomaterial Properties. Edited by J. Black and G. Hastings. Published in 1998 by Chapman Hall, Lx ndon. ISBN 0 412 60330 6. 

Ziegert and Lewis [9] measured the in vivo indentation properties of the soft tissues covering the anterior-medial tibiae. A preload of 22.4 N was used with indentors of 6 to 25 mm in diameter. The observed load displacement relationship were essentially linearly elastic. The structural sti ess was noted to vary by up to 70% between sites in one individual and up to 300% between individuals. Unfortunately, the thicknesses of overlying tissues were not determined at the different sites for the indi-viduds studied. 

Lanir et al. [3] measured the in vivo indentation behavior of human forehead skin with pressures up to 5kPa. The observed behavior was linearly elastic and calculated stiffnesses were 4 to 12 kPa. 

Bader and Bowker [1] studied the in vivo indentation properties of soft tissues on the anterior aspects of human forearms and thighs by applying constant pressures of 11.7 and 7 kPa respectively. Tissue thickness was measured by using a skinfold caliper and Poisson s rato was assumed to be 0.3. With these data, the stiffness of forearm and thigh tissue were calculated to be, respectively, 1.99 emd 1.51 kPa. 

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Ziegert, J.C. and Lewis, J.L. (1978) In-vivo mechanical properties of soft tissue covering bony prominence, Trans ASME (J. Biomech. Eng.), 100, 194-201. 

Hsieh Y-F, Silva MJ. In vivo fatigue loading of the rat ulna induces both bone formation and resorption and leads to time-related changes in bone mechanical properties and density. J Orthop Res. 2002 20 764-771. 

The nanofiller content in the first layer not only allowed obtaining thicker layers when increasing the content, but also played an important role in the mechanical properties of the newly formed bone surroimding the implant After in vivo implants in bones of rats, it was proved that the whole coating system enabled the isolation of potentially toxic ions coming from the implanted alloy. The addition of silica nanoparticles allowed the in vitro bioactivity and implant-tissue... 

Poly(lactide-coglycolide). Mixtures of lactide and glycolide monomers have been copolymerised in an effort to extend the range of polymer properties and rates of in vivo absorption. Poly(lactide- (9-glycolide) polymers undergo a simple hydrolysis degradation mechanism, which is sensitive to both pH and the presence of ensymes (32). 

Calpain inhibition may represent an important mechanism for future drug development. Control of calpain activity may limit the invasive properties of cells and thereby provides a possible mechanism to limit the invasiveness of tumors or inhibits the development of chronic inflammation. For the moment, pharmacological inhibitors of calpains are still not capable of differentiating among different calpain isoforms in cellular systems or in vivo. The importance of calpains in diseases will continue to stimulate the development of new and better inhibitors. 

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