Tendon injuries have, for many years, frustrated clinicians and patients alike due to their longevity and resistance to therapy. In recent years there has been good response in the extensor tendons of the lower limb to an intense painful eccentric exercise protocol. As yet there is no established reason known why a tendon should develop degeneration within its structure or why it should respond to the eccentric exercises. We do however know that, like bone, tendons are biologically active and rapidly adapt to the mechanical environment to which they are exposed. Recent investigations have revealed that within a tendon such as the Achilles or the patellar tendon there may be regions that experience different strains to the rest of the tendon. Much of this work has been in vitro and an ultimate goal would be the development of a non-invasive method by which intra-tendinous strain might be measured. The basis of this thesis is the validation of an existing grey-scale speckle pattern matching software programme developed for tracking motion through serial ultrasound images. Through in vitro and in vivo work we have developed its use for tracking the unique type of speckle found in tendons. By verifying, in vitro, that the displacements tracked in phantoms and tendons alike are representative of reality we provide confidence in the use of an exciting tool for measuring tendon motion in vivo. Furthermore, we have established the method by which the tracking can be adapted to accurately represent tendon strain in vitro which again provides assurance for its reliability when applied to examine tendon strain in vivo. The methods of data collection and analysis developed in this study provide the foundations for an exciting avenue of research into tendon biomechanics.

The aim of this project was the study of neutrophil recruitment and reverse transmigration using murine and human in vitro models of inflammation. Murine in vitro models of inflammation were developed using an immortalised microvascular cell line (MCEC-1) and primary murine vascular endothelial cells (mEC) isolated from heart and lung. We found that MCEC-1 could recruit murine neutrophils without the requirement of cytokine stimulation, although efficient transmigration did require such a stimulus. Primary cells required cytokine stimulation to recruit mEC. Interestingly, and in contrast to human EC, mEC were relatively insensitive to TNF-α stimulation, although IL-1β was a good stimulus for adhesion and migration. Using the IL-1β driven system we generated reverse migrated murine neutrophils and their phenotype and prolonged survival were assessed. The effect of shear stress and nitric oxide on the regulation of the process of reverse migration was examined. Using adoptive transfer strategies we investigated the fate of mRPMNs in vivo. A significant part of this work involved the study of human reverse migrated neutrophils at a proteomic level using two-Dimensional Fluorescence Gel Electrophoresis methodology to identify changes in neutrophils associated with reverse migration process. We found that murine reverse migrated neutrophils had a very similar surface phenotype to human reverse migrated cells. They also showed prolonged survival. However, our preliminary data on trafficking in vivo did not give a clear indication about their fate upon adoptive transfer into recipient mice. In vitro studies showed that flow generated shear stress and nitric oxide delayed, but did not inhibit, the process of reverse migration. Finally, the proteomics study revealed a number of metabolic, cytoskeletal and regulatory proteins that were differentially expressed in human reverse migrated neutrophils although the functional significance of these changes is yet to be explored.