Jean-Paul Roux | PubMed Health

PubMed2005

Evaluation and development of automatic two-dimensional measurements of histomorphometric parameters reflecting trabecular bone connectivity: correlations with dual-energy x-ray absorptiometry and quantitative ultrasound in human calcaneum.

In osteoporosis, bone fragility results from both bone loss and changes in trabecular microarchitecture, which can be quantified by bone histomorphometric parameters. Twenty human calcaneum were collected after necropsy. All measurements were performed at the same anatomical location. Bone histomorphometric parameters were measured on histological slides with an automatic image analyzer. The aims of our study were (1) to develop automatic measurements of four additional parameters reflecting trabecular network connectivity and complexity, i.e., trabecular bone pattern factor (TBPf), Euler number/tissue volume (Euler) according to the three definitions previously reported and to a fourth one established in the laboratory (Euler(strut.cavity)), marrow star volume, and interconnectivity index, and to determine their usefulness in microarchitecture characterization; and (2) to validate these parameters by evaluating their relationship with dual-energy X-ray absorptiometry and quantitative ultrasound (QUS) measurements performed on the same samples. The statistical analysis showed that TBPf and Euler(strut.cavity) appeared to be the most significant connectivity parameters, independently of bone quantity (bone mineral density, apparent density, cancellous bone volume). For QUS, after adjustment for bone quantity, only speed of sound (SOS) was significantly and negatively correlated to Euler(strut.cavity). Broadband ultrasound attenuation depends only on bone quantity. In conclusion, TBPf (a strut analysis parameter extrapolable in three dimensions) and Euler(strut.cavity) (the only bone connectivity parameter reflecting SOS) are two valid bone microarchitecture parameters. These new parameters were significantly correlated to the established trabecular structure parameters: trabecular thickness or trabecular spacing, being weakly correlated with SOS.

Absorptiometry, Photon↗

PubMed2004

An apparatus for temperature-dependent soft X-ray resonant magnetic scattering.

Interest in the use of soft X-ray resonant magnetic scattering techniques to probe the distribution of magnetic moments in thin films has exploded during the last few years. In this paper a novel diffractometer devoted to temperature-dependent soft X-ray resonant scattering is described. The principal features of the diffractometer are presented and illustrated through experiments performed at LURE during the commissioning phase.

Journal Article↗

PubMed2004

[New methods to measure bone quality].

Bone quality can be defined by the ability to resist fracture. Biomechanical testing represents a direct approach to evaluate bone quality. This quality is dependent of several determinants: intrinsic properties of bone including mineral and organic phases, amount of bone, bone architecture and bone size. These determinants are more or less linked to bone turnover, an absence or excessive one increasing bone fragility. Consequently, a minimum but not excessive level of bone turnover must be preserved in osteoporosis treatment.

Absorptiometry, Photon↗

PubMed2004

[Comparison of early bone histomorphometric effects of parathormone and alendronate in osteoporotic women].

Alendronate and teparatide, recombinant human PTH (1-34) are available treatment for osteoporosis in postmenopausal women. They act through opposite mechanisms of action. Alendronate reduces the remodeling of bone and thus increases secondary mineralization without any change in the amount of bone. Teriparatide, 20 micrograms/day, a bone forming agent would increase the amount of bone through two mechanisms, modeling--formation without resorption, and remodeling--resorption then formation with formation higher than resorption. Theses effects are present at the sixth month.

Alendronate↗