BACKGROUND:Some studies have found that local application of alendronate can promote osteogenesis,but less is reported on the process of distraction osteogenesis. OBJECTIVE:To observe the promoting effect of alendronate on rapid mandibular distraction in a rabbit model and explore its possible mechanism. METHODS:Thirty-six male New Zealand white rabbits were randomly divided into groups A,B and C(n=12 per group)after operation and rapid distraction(3-day delay period followed by 3-day distraction at 1.5 mm/12 hours).At the 1st,3rd and 7th days of the consolidation period,animal were injected with 200 μg/kg alendronate in group A and 100 μg/kg alendronate in group B,while those in group C were treated as controls.CT scanning and dual energy X-ray bone mineral density measurement were performed at 4 and 8 weeks of the consolidation period.After the radionuclide scanning was completed at the 4th week,several animals were sacrificed and the samples were collected for western blot assay and tartrate resistant acid phosphatase staining.A three-point bending test was performed after the animals were sacrificed at the 8th week. RESULTS AND CONCLUSION:CT results showed that bone formation in the distraction space of group B was significantly better than that in groups A and C.At the 4th week,the bone mineral density in group B was(0.092±0.010)g/cm2,which was 1.26 times higher than that in group A(P＜0.001)and 1.28 times higher than that in group C(P＜0.001).At the 8th week,the bone mineral density in group B was(0.175±0.029)g/cm2,which was 1.38 times higher than that in group A(P＜0.001)and 1.45 times higher than that in group C(P＜0.001).Tartrate resistant acid phosphatase staining showed that the number of osteoclast-like cells in group C were 2.83 times more than that in group A(P＜0.001)and 2.21 times more than that in group B(P＜0.001).The radionuclide intensity was higher in group C than in groups A and B.Western blot assay results showed that the expression of Runx2 was significantly stronger in group B than in groups A and C.The maximum biomechanical load in group B was(158.48±23.21)N,which was 1.26 times higher than that in group A(P=0.007)and 1.31 times higher than that in group C(P=0.003).To conclude,the low concentration of alendronate may promote rapid distraction osteogenesis of the rabbit mandible by inhibiting osteoclast signals.

Objective: To investigate the value of transrectal ultrasonography(TRUS) in the preoperative diagnosis and tumor T-staging of anorectal malignant melanoma(ARMM). Methods: The clinical and ultrasound data of 19 patients(22 lesions) with ARMM confirmed by pathology from February 2008 to Apirl 2019 in Fujian Medical University Affiliated Union Hospital were collected. TRUS was performed within one week before pathological examination. The sonographic features were summarized, ultrasonic typing was performed according to the lesion size and growth pattern, and the accuracies of preoperative ultrasound diagnosis and tumor staging were analyzed. Results: Among the 22 lesions, 63.64%(14/22) were with a distance of ≤3 cm between the anal verge and the lower margin of tumor, 68.18%(15/22) with regular shape, 81.82%(18/22) with clear boundary, and 63.64%(14/22) with Adler blood flow grading from Ⅱ to Ⅲ. The preoperative TRUS diagnostic coincidence rate was 73.68%(14/19), and the tumor T-staging accuracy was 75%(12/16), respectively. Conclusions TRUS exhibits certain sonographic characteristics, with high preoperative diagnosis rate and tumor T-staging accuracy in anorectal malignant melanoma, which is of great guiding significance for clinical diagnosis and treatment.