The effects of glucosamine hydrochloride on subchondral bone changes in an animal model of osteoarthritis.

OBJECTIVE: To quantify periarticular subchondral bone changes in a rabbit model of experimental osteoarthritis (OA), and to determine the effects of continuous administration of a clinically relevant dose of glucosamine HCl on subchondral bone changes in this model. METHODS: Anterior cruciate ligament transection (ACLT) was performed on the left femorotibial joints of 16 rabbits to induce OA. Ten rabbits that did not undergo ACLT served as unoperated controls. Eight rabbits that underwent ACLT and 6 control rabbits were treated with 100 mg of glucosamine daily, and the others were given a placebo. The articular cartilage was evaluated macroscopically and graded at the time of necropsy, 8 weeks after ACLT. Bone mineral density (BMD) was measured using dual-energy x-ray absorptiometry on the dissected distal femur and proximal tibia. Subchondral trabecular bone turnover, architecture, and connectivity, as well as subchondral plate thickness and mineralization were studied on the undecalcified tibia sections from each animal. RESULTS: Eight weeks after ACLT, most of the operated joints had various degrees of cartilage damage and fibrillation. Compared with the control group, the ACLT group had significantly increased subchondral bone turnover and lower BMD, bone volume, connectivity, and bone mineralization. The high bone turnover was significantly reduced in glucosamine-treated animals that underwent ACLT. In fact, there were no significant differences between the ACLT/glucosamine group and the control/glucosamine group in most of the bone parameters studied. CONCLUSION: This study shows that subchondral bone turnover, structure, and mineralization are significantly altered in the early stages of experimental OA, and that these changes are attenuated by glucosamine treatment.

Disease modifying effects of N-butyryl glucosamine in a streptococcal cell wall induced arthritis model in rats.

OBJECTIVE: To evaluate the effect of different doses of N-butyryl glucosamine (GlcNBu) on joint preservation and subchondral bone density and quality in a streptococcal cell wall (SCW) induced arthritis model in Lewis rats. METHODS: Chronic arthritis was induced in 36 female Lewis rats by a single intraperitoneal injection of SCW antigen. The 4 groups studied were: (1) no arthritis, no drug treatment; (2) arthritis, no drug treatment; (3) arthritis, oral GlcNBu 20 mg/kg/day; and (4) arthritis, oral GlcNBu 200 mg/kg/day. Inflammation (ankle swelling) was quantified throughout the clinical course; bone mineral density (BMD) was measured by dual-energy x-ray absorptiometry on dissected distal femurs and proximal tibiae, in user defined regions of interest. Qualitative and quantitative 3-D bone architecture changes were determined using microcomputerized tomography on the left tibiae. Subchondral plate thickness and trabecular bone connectivity were studied on the proximal tibia epiphyses from the central coronal sections of each scanned tibia. RESULTS: GlcNBu inhibited inflammatory ankle swelling at both 20 and 200 mg/kg/day, the latter being statistically significant, with an average reduction of 33%. GlcNBu preserved or enhanced BMD and bone connectivity and prevented further bone loss at both the high and the low dose. Comparisons of the isosurfaces and the architectural measures in the different groups showed that GlcNBu effectively protected the joint surfaces from further erosion in this model of chronic inflammatory arthritis. For some of the bone measurements, increasing doses of GlcNBu showed increasing protective effects, while for other measurements, effects were maximal at the lower dose. CONCLUSION: These data indicate that GlcNBu provides antiinflammatory and antierosive effects by preserving BMD, joint integrity, and bone architecture in involved joints of the SCW model.

Fluoride's effect on human dentin ultrasound velocity (elastic modulus) and tubule size.

Despite fluoride (F) use in caries prevention, not much is known about its effects on tooth quality. This study evaluated the effect of tooth F concentration ([F]) on selected dentin structural and mechanical properties. Third molars (n = 136) from Toronto, which has 1 part per million (p.p.m.) water [F], Montreal (0.2 p.p.m. water [F]), and Fortaleza (Brazil) (0.7 p.p.m. water [F]), were analyzed for [F], dental fluorosis (DF) severity, ultrasound velocity, and dentin tubule size and density. The enamel [F] was found to vary between 32 and 940 p.p.m., the dentin [F] was found to vary between 110 and 860 p.p.m., while the DF severity varied between TF0 and TF4. The enamel [F] showed no correlation with dentin [F], DF severity, ultrasound velocity, dentin tubule size or density. The dentin [F] correlated with DF severity, dentin tubule size, and ultrasound velocity. DF severity showed a correlation with dentin [F] and ultrasound velocity. It was concluded that dentin [F] is an indicator of dentin structural properties (dentin tubule size and ultrasound velocity), while DF severity is an indicator of dentin mechanical properties (ultrasound velocity).