Papers by Author: Tom Buckland

Abstract: Computerized X-ray microtomography (micro CT) is a powerful technique for imaging and quantification in biomedical materials research. Mapping of various tissue/implants in 3-dimension, which is not achievable with traditional histological slices, is particularly desirable in ex-vivo implant analysis. However, due to a variety of artifacts during image formation, especially the blurred interfaces due to the machine contrast transfer function and the partial volume effect, quantification based on traditional histograms is not accurate. In this work we propose a new 2-dimensional histogram and its application in the analysis of micro CT data of ex-vivo implants, which significantly improve the clarity of the definition of different phases and drastically reduced the artifacts of segmentation compared to conventional methods.

Abstract: In this study silicon release from SiHA into tissue culture medium was investigated under static and semi-dynamic conditions. The effect of silicon release under semi-dynamic conditions on alkaline phosphatase activity (ALP) and collagen I (CICP) expression by osteoblast like cells (HOS TE85) was also examined. Under static conditions a low level of silicon was released within 24 hours, this initial level dropped over 3-7 days but subsequently increased again by 10-14 days. Under semi-dynamic conditions silicon was released within 24 hours and was subsequently reduced with each medium change until equilibrating at close to 0 after 10 days. ALP and CICP showed significant variation in expression between culture conditions. In direct contact with SiHA ALP peaked at day 10 and CICP was constantly elevated. Cells grown in the presence of but not on SiHA expressed progressively decreasing levels of ALP from 7-14 days, with CICP peaking at day 10. On thermanox (TMX) ALP constantly increased and CICP peaked at day 10. The results indicate that silicon leaches out of the lattice of the SiHA crystal structure but may also be reprecipitated onto the substrate. We have also demonstrated that Si influences osteoblast metabolism and differentiation whether it is available as free silicon or 'bound' in the apatite lattice.