Because Mg-Ca-Zn alloys are biodegradable and obviate secondary implant removal, they are especially beneficial for pediatric patients. We examined the degradation performance of Mg-Ca-Zn alloys depending on the surface modification and investigated the in vivo effects on the growth plate in a skeletally immature rabbit model. Either plasma electrolyte oxidation (PEO)-coated (n = 18) or non-coated (n = 18) Mg-Ca-Zn alloy was inserted at the distal femoral physis. We measured the degradation performance and femoral segment lengths using micro-CT. In addition, we analyzed the histomorphometric and histopathologic characteristics of the growth plate. Although there were no acute, chronic inflammatory reactions in either group, they differed significantly in the tissue reactions to their degradation performance and physeal responses. Compared to non-coated alloys, PEO-coated alloys degraded significantly slowly with diminished hydrogen gas formation. Depending on the degradation rate, large bone bridge formation and premature physeal arrest occurred primarily in the non-coated group, whereas only a small-sized bone bridge formed in the PEO-coated group. This difference ultimately led to significant shortening of the femoral segment in the non-coated group. This study suggests that optimal degradation could be achieved with PEO-coated Mg-Ca-Zn alloys, making them promising and safe biodegradable materials with no growth plate damage.

Alterations in DNA methylation patterns are a hallmark of malignancy. However, the majority of epigenetic studies of Ewing's sarcoma have focused on the analysis of only a few candidate genes. Comprehensive studies are thus lacking and are required. The aim of the present study was to identify novel methylation markers in Ewing's sarcoma using microarray analysis. The current study reports the microarray‑based DNA methylation study of 1,505 CpG sites of 807 cancer‑related genes from 69 Ewing's sarcoma samples. The Illumina GoldenGate Methylation Cancer Panel I microarray was used, and with the appropriate controls (n=14), a total of 92 hypermethylated genes were identified in the Ewing's sarcoma samples. The majority of the hypermethylated genes were associated with cell adhesion, cell regulation, development and signal transduction. The overall methylation mean values were compared between patients who survived and those that did not. The overall methylation mean was significantly higher in the patients who did not survive (0.25±0.03) than in those who did (0.22±0.05) (P=0.0322). However, the overall methylation mean was not found to significantly correlate with age, gender or tumor location. GDF10, OSM, APC and HOXA11 were the most significant differentially‑methylated genes, however, their methylation levels were not found to significantly correlate with the survival rate. The DNA methylation profile of Ewing's sarcoma was characterized and 92 genes that were significantly hypermethylated were detected. A trend towards a more aggressive behavior was identified in the methylated group. The results of this study indicated that methylation may be significant in the development of Ewing's sarcoma.

Context. Denosumab is a monoclonal antibody against RANK ligand. Its administration in giant cell tumor of bone (GCTB) cases results in elimination of giant cells and new bone formation. Neoplastic stromal cells of GCTB harbor mutation of histone 3.3 and have pre-osteoblastic properties and thus express SATB2. Objectives. To (1) analyze histological changes in post-denosumab–treated GCTB, (2) analyze expression of H3.3G34W and SATB2 in pre- and post-denosumab–treated samples, and (3) to discuss why changes occur in the expression of not only H3.3G34W but also SATB2. Materials and Methods. Hematoxylin and eosin slides of 19 cases of denosumab-treated GCTB were reviewed. Immunohistochemical stains H3.3G34W and SATB2 were performed. The number of positive mononuclear cells were counted and graded. Results. Complete absence of osteoclast-like giant cells (OCLGCs) was noted in most cases along with a fibro-osseous component merging with peripheral shell of reactive bone. Irregular trabeculae of woven bone and osteoid with focal osteoblastic rimming was seen. Spindle cells were arranged predominantly in fascicular pattern. Morphometric analysis of H3.3G34W showed a mean of 68.8% positive stromal cells in pretreatment and a mean of 26.9% positive stromal cells in posttreated specimens with a statistically significant P value (.001). Mean percentage of SATB2-positive stromal cells in the pre- and posttreatment specimens was 36.46% and 20.8%, respectively. Conclusions. Our study validates that denosumab treatment results in marked reduction of OCLGCs with increased osteoblastic activity. Decreased expression of H3.3G34W in posttreatment may be a result of decreased antigenicity of neoplastic mononuclear cells. No significant change in SATB2 expression was noted.