Biomedical subjects

P Dallant

Publications and source records attributed to P Dallant.

3 recordsLinked to original sources

PubMed1989

Comparison of coral resorption and bone apposition with two natural corals of different porosities.

Previous studies showed that natural coral implanted into bone tissue was gradually resorbed and progressively replaced by newly formed bone. The objectives of this study were to compare the fate of two Madreporian corals, Porites and Acropora, after implantation during 1 and 2 months into sheep and pig long bones. These materials are identical in composition (CaCo3) but differ in volume (49 +/- 2%, 12 +/- 4%, respectively) and mean size (250 vs. 500 microns) of porosities. The non-decalcified histological slices were observed under light microscopy. Implant resorption and new bone formation were quantified through an automatic image analysis system. Quantitative results showed that the larger the porosity volume, the greater was the coral resorption as well as the new bone apposition. Large differences were found between the two animal species. Histological findings were identical to those previously reported: implants were resorbed and progressively replaced by newly formed bone. Coral was found to be an osteoconductive biomaterial which acted as a scaffold for a direct osteoblastic apposition and consequently could be an interesting alternative to bone auto-, allo-, or xenografts.

Animals↗

PubMed1986

Semi-automatic image-analysis applied to the quantification of bone microstructure.

Bone microstructure can be quantified by methods ranging from simple manual techniques to fully automatic image analysis systems. We describe a semi-automatic method, developed in BASIC and running on a laboratory microcomputer. Its core is based on two special algorithms for image conversion and for calculation. These two algorithms produce quantifying characteristics for any irregularly shaped structure, as defined by one or more open or closed contour lines. The quantification of these structural parameters relies only on contour line digitization. The improved efficiency of this semi-automatic method is a consequence of combining automatic calculations and human assistance. The structural parameters chosen were for a specific research project; the correlation between mechanical and microstructural properties of cortical bone, but they may readily be changed as circumstances demand.

Biomechanical Phenomena↗

PubMed1984

A postprocessing dual energy technique for vertebral CT densitometry.

The influence of the fat content in the cancellous bone on CT densitometry was measured on the excised vertebrae from 42 elderly human subjects. Using single energy CT, the decrease of the measured mineral content was 12% for a fat content of 10% by volume at a mean mineral content of 100-110 mg/cm3. Using a dual calibration at 85 and 130 kVp with reference to K2HPO4 for mineral and to alcohol for fat, our experiment showed that the mineral content of the vertebra can be measured with an accuracy of 6% referred to the ash-weight.

Absorptiometry, Photon↗