A review of the effects of tibolone on the skeleton

Bone health-related factors and the use of bisphosphonates in community setting--15-year follow-up study

The present study investigated the bone health related factors that were associated with the use of bisphosphonates (BP) among 2,050 postmenopausal Finnish women. Low BMD + low trauma energy fracture was the strongest determinant of BP use, while other secondary causes of osteoporosis were less strongly related with BP use. BP use was associated with reduced femoral neck (FN) and lumbar spine (LS) bone loss rate.

INTRODUCTION

The aim was to identify bone health related factors associated with the use of BP in a community setting.

METHODS

A population-based sample of 2,050 Finnish postmenopausal women was measured with dual X-ray absorptiometry at the FN and LS in 1989, 1994, 1999 and 2004, and information on osteoporosis risk factors, including low-trauma energy fractures, were collected with postal inquiries. Self-reported use of BP in 2004 was considered as the end point variable.

RESULTS

Among BP users, 12% had T-score > -2.0 SD and no fracture during follow-up (FU). In women without any bone medication, 26% had T-score < -2.0 SD or low-trauma energy fracture or both during the FU. In BP users, a significant reduction in FN and LS bone loss rate, cumulative with duration of use, was observed in ANCOVA (p < 0.001). Among BP users, there was a significantly higher proportion of women with several independent risk factors for osteoporosis and more spine and humerus fractures but less ankle fractures. T-score < -2 SD combined with low-trauma energy fracture was significantly related to the use of BPs (p < 0.001, OR = 15.96) and T-score < -2 SD was a stronger predictor of BP use (p < 0.001, OR = 13.29) than fracture (p > 0.05, OR = 1.35) in multivariate logistic regression. Other factors related with BP use were vitamin D use (p = 0.001, OR = 2.27), high number of medications (p < 0.001, OR = 1.26) and rheumatoid arthritis (p < 0.05, OR 2.55).

CONCLUSIONS

These findings reveal the recent bone health-related indications for BP prescription.

Enantioselective production of 3-hydroxy metabolites of tibolone by yeast reduction

The enantioselective reduction of tibolone into the corresponding 3alpha-hydroxy or 3beta-hydroxy metabolite can be controlled by choosing suited strains of yeasts and biotransformation conditions. A restricted screening performed among 52 yeasts showed that the 3alpha-epimer was preferentially obtained with high epimeric purity with various strains (i.e. with Kluyveromyces lactis CBS 2359), while only Saccharomyces cerevisiae CBS 3093 gave the 3beta-epimer as major product. The reduction of tibolone with K. lactis CBS 2359 and S. cerevisiae CBS 3093 was optimised. S. cerevisiae CBS 3093 furnished a 96:4 ratio of 3beta/3alpha with complete molar conversion within 72h when the initial concentration of substrate was below 2.5g/L. K. lactis CBS 2359 gave a 99:1 ratio of 3alpha/3beta with complete conversion in 64h.

Growth factor delivery for bone tissue repair: an update

Growth factors (GFs) are endogenous proteins capable of acting on cell-surface receptors and directing cellular activities involved in the regeneration of new bone tissue. The specific actions and long-term effects of GFs on bone-forming cells have resulted in exploration of their potential for clinical bone repair. The concerted efforts have led to the recent approval of two GFs, bone morphogenetic protein-2 and osteogenic protein-1, for clinical bone repair, and human parathryroid hormone (1-34) for augmentation of systemic bone mass. This review provides a selective summary of recent (2001-2004) attempts for GF delivery in bone tissue regeneration. First, a summary of non-human primate studies involving local regeneration and repair is provided, with special emphasis on the range of biomaterials used for GF delivery. Next, efforts to administer GFs for systemic augmentation of bone tissue are summarised. Finally, an alternative means of GF delivery, namely the delivery of genes coding for osteogenic proteins, rather than the delivery of the proteins, is summarised from rodent models. To conclude, future avenues of research considered promising to enhance the clinical application of GFs are discussed.