Regulation of DMT1 on autophagy and apoptosis in osteoblast.

Iron overload has recently been associated with the changes in the bone microstructure that occur in osteoporosis. However, the effect of iron overload on osteoblasts is unclear. The purpose of this study was to explore the function of divalent metal transporter 1 (DMT1) in the pathological processes of osteoporosis. Osteoblast hFOB1.19 cells were cultured in medium supplemented with different concentrations (0, 50, 100, 200, 300, 400, 500 µmol/L) of ferric ammonium citrate (FAC) as a donor of ferric ions. We used western blotting and immunofluorescence to determine the levels of DMT1 after treatment with FAC. Apoptosis was evaluated by detecting the levels of cleaved caspase 3, BCL2, and BAX with western blotting. Autophagy was evaluated by detecting the levels of LC3 with western blotting and immunofluorescence. Beclin-1 expression was also assessed with western blotting. The autophagy inhibitor 3-methyladenine was used to determine whether autophagy affects the apoptosis induced by FAC. Our results show that FAC increased the levels of DMT1, upregulated the expression of BCL2, and downregulated the apoptosis-related proteins cleaved caspase 3 and BAX. Both LC3I/LC3II levels and beclin-1 were also increased, indicating that FAC increases the accumulation of autophagosomes in hFOB1.19 cells. FAC-induced autophagy was increased by the apoptosis inhibitor 3-MA but was reduced in DMT1 shRNA hFOB1.19 cells. These results suggest that the increased expression of DMT1 induces iron overload and iron overload induces osteoblast autophagy and apoptosis, thus affecting the pathological processes of osteoporosis. Clarifying the mechanisms underlying the effects of DMT1 will allow the identification of novel targets for the prevention and treatment of osteoporosis.

[Treatment and analysis of the early postoperative complications of tibial plateau fractures].

OBJECTIVE: To analysis the early complications of tibial fracture and its related factors, and propose a solution. METHODS: From December 2003 to December 2013,38 patients with early complications of tibial plateau fracture after operation were retrospectively analyzed. There were 35 males and 3 females, aged from 37 to 69 years old (averaged 42.3 years). According to Schatzker classification, 3 cases were classified as type II, 2 cases as type III, 2 cases as type IV, 19 cases as type V, 12 cases as type VI. The intervals between injury and operation ranged from 9 hours to 9 days, 26 cases within 3 days. Fifteen cases were treated with internal fixation of plates and 23 were treated by plate fixation and bone transplantation. Early complications included skin necrosis in 15 cases, infection in 6 cases, osteofascial compartment syndrome in 3 cases, common peroneal nerve injury in 2 cases, the superficial peroneal nerve injury in 3 cases, popliteal artery injury in 2 cases, loss of reduction in 7 cases. RESULTS: The wound of 14 cases healed at the first stage and 24 cases healed delay. Hospitalization days ranged from 7 to 67 days (averaged 25.6 days). All patients were followed up for 12 to 36 months with an average of 16.4 months. The fracture healing time ranged from 3 to 9 months (averaged 6.9 months). According to Merchant knee function evaluation criteria, the results were excellent in 19 cases, good in 12, fair in 5 and poor in 2. CONCLUSION: Early complications of tibial fracture after operation is closely associated with the severe fracture complexity and related with preoperative preparation, surgical timing, operation incision selection and surgical technique. Early detection and timely processing reduce damage.

[Experimental study of Gukangling Decoction combined with technetium [99Tc] methylene diphosphonate injection in treating osteoporotic rabbits].

OBJECTIVE: To evaluate the advantage of Gukangling Decoction (GKLD), a compound traditional Chinese herbal medicine, combined with technetium [(99)Tc] methylene diphosphonate injection ((99)Tc-MDP) in treating osteoporosis in rabbits. METHODS: A rabbit model of osteoporosis was established by intramuscular injection of dexamethasone (DX). Fifty-six rabbits were divided into 8 groups: Group A, B, C, D, E, F, G and H. Rabbits in groups A and B were intramuscularly injected normal saline as normal control, groups C and D were untreated groups, rabbits in group E were treated by (99)-MDP, rabbits in group F were treated by aminodiphosphate, rabbits in group G were treated by GKLD, and rabbits in group H were treated by (99)-MDP and GKLD. Rabbits in groups A and C were executed to demonstrate the establishment of the rabbit model of osteoporosis at the 8th week of experiment. Rabbits in the other six groups were executed after 16-week experiment (8-week treatment), and then bone structure and cell shape were observed by electron microscope, X-ray, CT and emission computed tomography (ECT). Bone density, biomechanical parameters, the levels of bone specific alkaline phosphatase (BALP) and bone Gla protein (BGP) were measured too. RESULTS: After 8-week of intramuscular injection of DX, the bone trabecula in group A were regular and showed normal configuration, while the bone trabecula in group C were sparse, ruptured and showed damaged form. The bone density and biomechanical parameters in group A were higher than those in group C, indicating that the rabbit model of osteoporosis was established successfully. At the 9th week of experiment, the results of cell pathology in group D showed that the bone trabeculas were sparse, ruptured, defected or had hollow section, but the bone trabeculas in group B were regular and dense. The bone trabeculas in groups H and E were restored, and were thicker than those in group D. The bone quality in groups H and E was better than group D significantly, the bone quality in group F was better than group G, and the bone quality in group G was better than group D slightly. CONCLUSION: GKLD combined with (99)-MDP had superiority in treating osteoporosis of rabbits as compared with the respective single therapy.