P423 Comparison of harmfulness between fluoride and cadmium ions on the crystal nucleation process M. Kakei a, *, T. Sakae b , H. Mishima c , M. Yoshikawa d a Division of Oral Anatomy, Meikai University School of Dentistry, Sakado, Japan b Department of Histology, Embryology, Anatomy, Nihon University School of Dentistry at Matsudo, Matsudo, Japan c Department of Health Science, Kochi Gakuen College, Kochi, Japan d Division of Orthodontics, Meikai University School of Dentistry, Sakado, Japan Recently, we have demonstrated that both fluoride (F) and cadmium (Cd) ions cause crystal defects in developing tooth enamel. Also, we have suggested that both ions might contribute to increased risk for the development of bone diseases such as osteomalacia and osteoporosis. These substances interrupt the supply of carbonate ions for the crystal nucleation process in several calcifying hard tissues. In general, the harmfulness of Cd ions is well established as a risk factor for ouch-ouch (itai-itai) disease, whereas many people remain less aware of that posed by F ions, which we regard as also a latent risk factor for bone disease. Therefore, we conducted this study to raise awareness of the harmfulness of F for hard tissue formation by comparing it with that of Cd. We examined the developing tooth enamel of rats because it is suitable for assessing crystal defects and the basic mechanism of crystal formation is the same in enamel, dentin and bone. Rats were fed water containing either F (2 ppm) or Cd (20, 40, 100 ppm) ions. Enzymatic activity of carbonic anhydrase was measured using a differential gas pressure method since carbonic anhydrase, rather than alkaline phosphatase, plays a key role in the central-dark-line formation at the initial stage of mineralization. The results indicated that the harmful effects of 2 ppm F on the crystal nucleation process to be approximately equivalent to 40 ppm Cd. From the results, we conclude that the harmfulness of F to hard tissue formation is approximately 20 times greater than that of Cd. This study was supported partly by the Frontier Science Projects to LEBRA at Nihon University and subsidized by the Japanese Ministry of Education, Science, Sports and Culture (2000–2004, 2005–2007), and by a Grants-in-Aid for science research from the Ministry of Education, Culture, Sport, Science and Technology of Japan (20592168). Conflict of interest: None declared. doi:10.1016/j.bone.2009.03.335 P424 A long-term diet enriched in omega-3 fatty acids improves cortical bone structure and mechanical properties in mice N. Bonnet*, S. Ferrari Rehabilitation and Geriatrics, Geneva University Hospital and Faculty of Medicine, Service of Bone Diseases, Geneva, Switzerland Background: Western diet is characterized by low intake of omega-3 fatty acids, i.e eicosapentaenoic acid (EPA) and docosahex- aenoic acid (DHA). A low ratio of omega-3/omega-6 increases risk of chronic disorders, including cardiovascular diseases (CVD) and osteoporosis. In turn, fish oil has been suggested to prevent CVD, bone loss and others. We investigated whether a long-term diet enriched in omega-3s, would improve bone structure and strength in aging mice. Methods: Thirty female mice received a diet enriched in DHA or EPA (2 mg/g of diet) or an isocaloric control diet supplemented with bovine fat (18% of fat), from 3 to 17 months of age. Changes in body composition, bone mass and structure, and biochemical markers of bone turnover were analyzed longitudinally in vivo, whereas biomechanical properties of the femur were analysed by 3-point bending at sacrifice. Results: DHA and EPA increased fat gain with ageing compared to controls (+76% and +66.5% respectively, vs +42%, p > 0.05); leptin levels were also higher in EPA and DHA (7.3±0.7 ng/ml and 8.5± 0.5 ng/ml, respectively, vs 4.5±0.9 ng/ml in controls, p <0.01). EPA, but not DHA, blunted the age-related decline of osteocalcin levels (-70% vs -83% in controls, p < 0.05), without significant effects on TRAcP5b. However, BMD changes were not affected by either EPA or DHA, nor was the long-term loss of trabecular bone volume in femur (BV/TV - 90%, -91%, and - 94% in EPA, DHA and controls respectively) or caudal vertebrae. In contrast, cortical volume and thickness increased significantly more with EPA compared to controls (BV: +48.8% vs +35.2%; CtTh: +25.7% vs +18.1%, respectively, p <0.05), whereas DHA had no significant effects on these para- meters. Accordingly, EPA significantly increased femur bone strength (ultimate stress, 4.3 ± 0.2 N mm vs 5.2 ± 0.4 N mm; toughness 2515±188 N/mm 2 vs 2075±100 N/mm 2 in controls, all p <0.05), and stiffness was not significantly different, whereas DHA also increased ultimate stress (2596±257 N/mm 2 , p < 0.05). Conclusion: These data suggest that long-term intake of omega- 3s, particularly EPA, may improve structural and mechanical proper- ties of cortical bone in the femur, without affecting trabecular bone loss. These positive effects on cortical bone could be partially explained by an increased of leptin levels and/or bone formation. Conflict of interest: None declared. doi:10.1016/j.bone.2009.03.336 P425 Body composition estimated by DXA scan in patients with systemic sclerosis N. Gavrilov*, N. Pilipović, K. Simić-Pašalić, G. Radunović, N. Damjanov Rheumatology, Institute of rheumatology, Belgrade, Serbia Background: Classic description of patients with systemic sclerosis (SSc) usually defines them as lean persons with significantly decreased body weight. Surprisingly, there are few studies who actually tried to prove this widely accepted opinion 1 . Aims: To investigate body composition in patients with SSc and to compare it with healthy controls. Methods: Body composition was estimated in 30 postmenopausal patients with SSc, disease duration 9.06 ±6.8 yrs (min 1, max 26), age 58.8±5.6 yrs and 30 healthy female, age 60.1±6.4. No difference in age between groups was found. For body composition measurement Lunar Advance Prodigy scan with estimation of three compartments (fat and lean tissue and bone mineral content) was used. Results: Significant difference between group with SSc and healthy controls was found in body mass index (BMI) (25.2 vs. 25.9, p <0.005), total weight (65.7 kg vs. 72.6 kg, p < 0.03), android fat tissue quantity (42.2 kg vs. 46.3 kg, p < 0.042), android/ginoid fat tissue ratio (0.857 vs. 0.953, p < 0.008) and amount of lean tissue (37.3 kg vs. 40.1 kg, p <0.02). There was no difference in the total quantity (26.4 kg vs. 30.5 kg) and percentage of fat tissue (40.2% vs. 42%), trunk/whole body fat (0.5 vs. 0.5) and extremities/whole body fat ratio (0.37 vs. 0.35), as well as in bone mineral content (BMC) (2.24 kg vs. 2.22 kg) between groups. Conclusion: Despite traditional opinion, BMI and percentage of fat tissue indicate that patients with SSc are overweight. This is, probably, a consequence of earlier diagnosis with mild case recogni- tion and early treatment introduction. Lower values of BMI, total weight and amount of lean tissue compared to healthy controls suggest possible role of diffuse ischemia as a consequence of Abstracts / Bone 44 (2009) S339–S450 S414