Biologic Response to Carbonated Hydroxyapatite Associated with Orthopedic Device: Experimental Study in a Rabbit Model

BACKGROUND: Carbonated hydroxyapatite (CHA) and related calcium phosphates have been studied for many years as implant materials due to their similarity with the mineral phase of bone. The main limitation of CHA ceramics as well as other bioactive materials is that they have poor mechanical proprieties. It is thought that the mechanical device can cause an increase in metabolic activity and bone healing. In this study we investigated the reactivity and tissue behaviour of implanted CHA biomaterial reinforced by mini external fixator. METHODS: The evaluation of biomaterial biocompatibility and osteogenesis was performed on a rabbit model over a period of 6 weeks by radiological, histological and scanning electron microscopy (SEM) coupled with energy dispersive X-ray SEM-energy-dispersive X-ray (EDX) analysis. RESULTS: While rabbits treated with CHA exhibited more bone formation, and fibrous tissue was observed when empty bone defects were observed. EDX analysis detected little calcium and phosphorus on the surface of the bone that was not implanted, while high content of calcium (62.7%) and phosphorus (38%) was found on the interface bone cement. CONCLUSIONS: Bone repairing showed that the mini external fixator stimulated the ossification which was pushed when grafted by CHA. This effect may play an important role in the prevention of implant loosening.

Inhibitory effect of estrogens, phytoestrogens, and caloric restriction on oxidative stress and hepato-toxicity in aged rats / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To investigate the protective effect of 17beta-estradiol (E2), peganum harmala extract (PHE) administration and calorie restriction (CR) treatment (60%) on oxidative stress and hepato-toxicity in aged rats.</p><p><b>METHODS</b>Eighteen months old animals that were treated at the age of 12 months were divided into 4 groups: normal control group with free access to food, E2 treatment group, PHE treatment group and CR treatment group of the food given to control group. Six male rats at the age of 4 months were used as a reference group.</p><p><b>RESULTS</b>Aging significantly decreased superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX), and increased lactate deshydrogenase (LDH), gamma-glytamyl transferase (GGT), phosphatase alkalines (PAL), aspartate and lactate transaminase (AST and ALT) activities in the liver. Aging also induced an increased lipid peroxidation level, histological changes and a decreased E2 level. However, treatment with E2, PHE, and CR increased 17beta-estradiol, and decreased hepatic dysfunction parameters and lipid peroxidation as well as histological changes in the liver of aged rats.</p><p><b>CONCLUSION</b>The antioxidant and hepatoprotective activity of PHE and CR is possibly attributed to its ability to increase E2 level, which as an antioxidant, acts as a scavenger of ROS. Further studies on the pharmaceutical functions of E2 in males may contribute to its clinical application.</p>