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This study indicated risk factors for serious complications of ESD. Large resected tumor size was a risk factor for post-operative bleeding, while long operation time was a risk factor for perforation. Information regarding operation risk factors should be useful for planning strategies for ESD.

Acidic proteins play an important role during mineral formation in biological systems, but the mechanism of mineral formation is far from understood. In this paper, we report on the relationship between the structure of a protein and hydroxyapatite deposition under biomimetic conditions. Sericin, a type of silk protein, was adopted as a suitable protein for studying structural effect on hydroxyapatite deposition, since it forms a hydroxyapatite layer on its surface in a metastable calcium phosphate solution, and its structure has been reported. Sericin effectively induced hydroxyapatite nucleation when it has high molecular weight and a b sheet structure. This indicates that the specific structure of a protein can effectively induce heterogeneous nucleation of hydroxyapatite in a biomimetic solution, i.e. a metastable calcium phosphate solution. This finding is useful in understanding biomineralization, as well as for the design of organic polymers that can effectively induce hydroxyapatite nucleation.

A novel synthetic peptide corresponding to BMP-2 residues 73-92 that can induce bone formation and can form a conjugate with a carrier to localize its effect has been reported previously. The synthetic peptide was bound to a BMP-2-specific receptor, and it elevated both the alkaline phosphatase activity and the osteocalcin mRNA in the murine multipotent mesenchymal cell line, C3H10T1/2. The 73-92 peptide also induced ectopic bone formation when conjugated to a covalently crosslinked alginate gel and implanted into a rat's calf muscle. Here, it is reported that the 73-92 peptide-conjugated alginate gel particles significantly promoted the repair of rat tibial bone defects, whereas the alginate gel sponge that the peptide was conjugated with was less effective. Further acceleration and denser bone regeneration was achieved when the 73-92 peptide-conjugated alginate gel particles were coimplanted with syngeneic rat bone-marrow stromal cells. Therefore, the 73-92 peptide can induce differentiation of osteoblast precursor cells into osteoblasts, and can activate osteoblasts to promote the repair of bone defects.

Bone morphogenetic protein-2 (BMP-2) promotes the formation and regeneration of bone and cartilage, and therefore constitutes the most promising candidate for a bone repair material. However, it also has a wide range of functions, such as in organogenesis and apoptosis. Therefore, we investigated a novel synthetic peptide corresponding to residues 73-92 of BMP-2. This peptide bound to a BMP-2-specific receptor and elevated both alkaline phosphatase activity and osteocalcin mRNA in the murine cell line, C3H10T1/2. The 73-92 peptide also induced ectopic calcification when conjugated to a covalently crosslinked alginate gel. Here we report that the 73-92 peptide-conjugated alginate gel showed prolonged ectopic calcification for up to 7 weeks in rat calf muscle. In contrast, rhBMP-2-impregnated collagen gel showed maximum ectopic calcification at 3 weeks, and the calcified products that had formed disappeared after 5 weeks. Histological examination showed that the 73-92 peptide-conjugated alginate gel induced many osteoblast-like cells and few osteoclasts. In contrast, rhBMP-2-impregnated collagen gel induced many osteoclasts. These results suggest that the 73-92 peptide on alginate gel remains active at the implanted site, continuously induces differentiation of osteoblast precursor cells into osteoblasts, and activates osteoblasts to promote ectopic calcification.

Background: This retrospective study aimed to determine risk factors associated with serious complications of endoscopic submucosal dissection of gastric tumors in multicenters compared between high- and low-volume centers. Methods: Between 2001 and 2010, gastric endoscopic submucosal dissection was performed in 1,190 lesions of 1,082 patients in five hospitals in Saga, three high-volume and two low-volume centers. Risk factors for serious complications were evaluated. Patients’ background characteristics were evaluated, including anticoagulants use and underlying diseases. Results: Postoperative bleeding was detected in 75 patients (6.9%), and perforation was detected in 40 patients (3.7%). Most postoperative bleeding and perforation cases were recovered with endoscopic procedures, although one case of each complication was treated by emergency surgery. Multivariate analysis indicated that risk factors for perforation were tumor location, massive submucusal invasion, endoscopists’ experience of 100–149 cases and hypertension, and that risk factors for postoperative bleeding were tumor location, resected tumor size, and scar lesion. The serious complications were not different between high- and low-volume centers. Conclusions: The present study indicated that risk factors for perforation during endoscopic submucosal dissection were tumor, endoscopist and patient related, although risk factors for postoperative bleeding were tumor related. There was no difference in complications between high- and low-volume centers.

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