Biomedical subjects

Gaël Grimandi

Publications and source records attributed to Gaël Grimandi.

3 recordsLinked to original sources

PubMed2006

Quantitative and reliable in vitro method combining scanning electron microscopy and image analysis for the screening of osteotropic modulators.

The increased generation and up-regulated activity of bone resorbing cells (osteoclasts) play a part in the impairment of bone remodeling in many bone diseases. Numerous drugs (bisphosphonates, calcitonin, selective estrogen receptor modulators) have been proposed to inhibit this increased osteoclastic activity. In this report, we describe a pit resorption assay quantified by scanning electron microscopy coupled with image analysis. Total rabbit bone cells with large numbers of osteoclasts were cultured on dentin slices. The whole surface of the dentin slice was scanned and both the number of resorption pits and the total resorbed surface area were measured. Resorption pits appeared at 48 h and increased gradually up to 96 h. Despite the observation of a strong correlation between the total resorption area and the number of pits, we suggest that area measurement is the most relevant marker for osteoclastic activity. Osteotropic factors stimulating or inhibiting osteoclastic activity were used to test the variations in resorption activity as measured with our method. This reproducible and sensitive quantitative method is a valuable tool for screening for osteoclastic inhibitors and, more generally, for investigating bone modulators.

Animals↗

PubMed2005

Novel biomaterials for bisphosphonate delivery.

One type of gem-bisphosphonate (Zoledronate) has been chemically associated onto calcium phosphate (CaP) compounds of various compositions. For that purpose, CaP powders of controlled granulometry have been suspended in aqueous Zoledronate solutions of variable concentrations. Using mainly (31)P NMR spectroscopy, two different association modes have been observed, according to the nature of the CaP support and/or the initial concentration of the Zoledronate solution. beta-tricalcium phosphate (beta-TCP) and mixtures of hydroxyapatite and beta-TCP (BCPs) appear to promote Zoledronate-containing crystals formation. On the other hand, at concentrations <0.05 mol l(-1) CDAs (calcium deficients apatites) seem to undergo chemisorption of the drug through a surface adsorption process, due to PO(3) for PO(4) exchange, that is well described by Freundlich equations. At concentrations >0.05 mol l(-1), crystalline needles of a Zoledronate complex form onto the CDAs surface. The ability of such materials to release Zoledronate, resulting in the inhibition of osteoclastic activity, was shown using a specific in vitro bone resorption model.

Animals↗

PubMed2004

Alveolar bone regeneration for immediate implant placement using an injectable bone substitute: an experimental study in dogs.

BACKGROUND: The aim of the present study was to assess the efficacy of a ready-to-use injectable bone substitute for bone regeneration around dental implants placed into fresh extraction sockets. METHODS: Third and fourth mandibular premolars were extracted from three beagle dogs and the interradicular septa were surgically reduced to induce a mesial bone defect. Thereafter, titanium implants were immediately placed. On the left side of the jaw, mesial bone defects were filled with an injectable bone substitute (IBS), obtained by combining a polymer and biphasic calcium phosphate ceramic granules. The right defects were left unfilled as controls. After 3 months of healing, specimens were prepared for histological and histomorphometric evaluations. RESULTS: No post-surgical complications were observed during the healing period. In all experimental conditions, histological observations revealed a lamellar bone formation in contact with the implant. Histomorphometric analysis showed that IBS triggers a significant (P<0.05) increase in terms of the number of threads in contact with bone, bone-to-implant contact, and peri-implant bone density of approximately 8.6%, 11.0%, and 14.7%, respectively. In addition, no significant difference was observed when number of threads, bone-to-implant contact, and bone density in the filled defects were compared to the no-defect sites. CONCLUSION: It is concluded that an injectable bone substitute composed of a polymeric carrier and calcium phosphate significantly increases bone regeneration around immediately placed implants.

Alveolar Process↗