NDGA enhances the physicochemical and anti-biodegradation performance of dentin collagen.

OBJECTIVES: Collagen fibrils from carious dentin matrix are prone to enzymatic degradation. This study investigates the feasibility and mechanism of nordihydroguaiaretic acid (NDGA), as a collagen crosslinker, to bio-modify the demineralized dentin matrix. METHODS: The physicochemical properties of the crosslinked dentin matrix were characterized by swelling ratio, ninhydrin assay, Fourier Transform Infrared spectroscopy, and atomic force microscopy. The collagenase degradation resistance was evaluated by measuring loss of dry mass, hydroproline release, loss of elasticity, and micro-nano structure integrity. The cytotoxicity of NDGA-crosslinked dentin collagen was evaluated by flow cytometry. RESULTS: NDGA crosslinked dentin matrix without destroying the integrity of collagen. Mechanistically, NDGA formed bisquinone bond between two adjacent o-quinone groups, resulting in NDGA polymeric matrix in which collagen fibrils were embedded. NDGA modification could significantly enhance the stiffness of dentin matrix at macro-nano scale. The NDGA-crosslinked dentin matrix exhibited remarkably low collagen degradation and sustained bulk elasticity after collagenase challenge, which were attributed to decreased water content, physical masking of collagenase bind sites on collagen, and improved stiffness of collagen fibrils. Notably, NDGA-crosslinked dentin matrix exhibited excellent biocompatibility. CONCLUSION: NDGA, as a biocompatible collagen crosslinker, improves the mechanical properties and biodegradation resistance of demineralized dentin matrix.

Hybrid endoscopic submucosal dissection: An alternative resection modality for large laterally spreading tumors in the cecum?

BACKGROUND: Endoscopic resection for large, laterally spreading tumors (LSTs) in the cecum is challenging. Here we report on the clinical outcomes of hybrid endoscopic submucosal dissection (ESD) in large cecal LSTs. METHODS: We retrospectively reviewed data from patients with cecal LSTs ≥ 2 cm who underwent ESD or hybrid ESD procedures between January of 2008 and June of 2019. We compared the baseline characteristics and clinical outcomes, including procedure time, the en bloc and complete resection rates, and adverse events. RESULTS: A total of 62 patients were enrolled in the study. There were 27 patients in the ESD group and 35 patients in the hybrid ESD group, respectively. Hybrid ESD was more used for lesions with submucosal fibrosis. No other significant differences were found in patient characteristics between the two groups. The hybrid ESD group had a significantly shorter procedure time compared with the ESD group (27.60 ± 17.21 vs. 52.63 ± 44.202 min, P = 0.001). The en bloc resection rate (77.1% vs. 81.5%, P = 0.677) and complete resection rate (71.4% vs. 81.5%, P = 0.359) of hybrid ESD were relatively lower than that of the ESD group in despite of no significant difference was found. The perforation and post-procedure bleeding rate (2.9% vs. 3.7%, P = 0.684) were similar between the two groups. One patient perforated during the ESD procedure, which was surgically treated. One patient in the hybrid ESD group experienced post-procedure bleeding, which was successfully treated with endoscopic hemostasis. Post-procedural fever and abdominal pain occurred in six patients in the ESD group and five patients in the hybrid ESD group. One patient in the ESD group experienced recurrence, which was endoscopically resected. CONCLUSION: The results of this study indicate that hybrid ESD may be an alternative resection strategy for large cecal LSTs with submucosal fibrosis.

The outcomes of modified endoscopic mucosal resection and endoscopic submucosal dissection for the treatment of rectal neuroendocrine tumors and the value of endoscopic morphology classification in endoscopic resection.

BACKGROUND: To compare the outcomes of modified endoscopic mucosal resection (m-EMR) and endoscopic submucosal dissection (ESD) for rectal neuroendocrine tumors (NETs) and evaluate the value of endoscopic morphology classification in endoscopic resection (ER). METHODS: Patients with rectal NET diameters less than 2 cm who were treated between April 2007 and January 2019 were enrolled. The endoscopic morphology of rectal NETs was classified based on the endoscopic views. Patients who underwent ESD and m-EMR were compared. Baseline characteristics as well as en bloc resection, complete resection, the procedure time, adverse events and the risk factors associated with incomplete resection were analyzed. RESULTS: A total of 429 patients with 449 rectal NETs were enrolled for the classification of endoscopic morphology and were classified into four types (Ia, IIb, II, and III). There were 79 patients in the m-EMR group and 259 patients in the ESD group before matching. Propensity score matching created 77 pairs between the two groups that were well balanced. The mean procedure time was significantly shorter for m-EMR than for ESD (9.1 ± 4.4 min vs 16.0 ± 7.9 min, P = 0.000). The rates of en bloc resection (98.7% vs 100%; P = 1.000), complete resection (90.9% vs 93.5%, P = 0.548) and adverse events (2.6% vs 2.6%, P = 1.000) were similar between the two groups. Univariate and multivariate analyses showed that histopathological grade and endoscopic morphology were associated with incomplete resection. CONCLUSION: Both ESD and m-EMR are effective and safe for the treatment of rectal NETs. Endoscopic morphology should be considered along with histopathological grade for ER.

Efficacy and safety of hybrid endoscopic submucosal dissection compared with endoscopic submucosal dissection for rectal neuroendocrine tumors and risk factors associated with incomplete endoscopic resection.

BACKGROUND: Neuroendocrine tumors (NETs) are rising in prevalence, particularly with the rectal area. This study evaluated and compared the safety and effectiveness of hybrid endoscopic submucosal dissection (ESD) with those of ESD for rectal NETs and risk factors associated with incomplete endoscopic resection. METHODS: A total of 272 consecutive patients who underwent ESD or hybrid ESD for rectal NETs at the Chinese PLA General Hospital in the period from February 2011 to September 2018 were involved in this study. Data were collected from clinical and endoscopic databases. The procedure time, en bloc resection, complete resection, complication, and recurrence rates were evaluated. RESULTS: In the hybrid ESD group were 111 patients (who had 119 lesions between them), with a further 161 patients (164 lesions) in the ESD group. No significance was found in baseline characteristics between the two groups. Hybrid ESD had a significantly shorter mean procedure time than ESD (13.2±8.3 vs. 18.1±9.7 min, P=0.000). Hybrid ESD showed similar en bloc resection (99.2% vs. 98.2%; P=0.373), complete resection (94.1% vs. 90.9%, P=0.641), and postprocedural bleeding (2.5% vs. 0.6%, P=0.313) rates to ESD. Univariate and multivariate analysis showed that higher histopathological grade was associated with incomplete resection. CONCLUSIONS: For rectal NET, both ESD and hybrid ESD are effective and safe forms of treatment. Hybrid ESD provides an alternative option in the treatment of rectal NETs. Further developments are needed to improve the complete resection rate, especially concerning tumors with higher histopathological grade.

Application of enriched bone marrow compound with fibrin glue in repairing old radial bone defect in rabbits / 中国医学科学院学报

<p><b>OBJECTIVE</b>To explore the feasibility of using enriched bone marrow (BM) compound with fibrin glue (FG) in repairing old radial bone defect.</p><p><b>METHODS</b>Totally 36 New Zealand rabbits were equally randomized into three groups: simple FG group, BM+FG group, and enriched BM+FG group. A 1.5-cm segmental bone defect was made at the left radial in each animal. After one month, the defect was implanted with the engineered bone. Before implantation, a compound of enriched BM with FG underwent electron microscopy, long-term culture, and bacteriological culture. Four, 8, and 12 weeks after operations, the osteogenetic effect was evaluated using X-ray observation, HE staining, or Van Gieson staining, and a semi-quantitative analysis was performed.</p><p><b>RESULTS</b>Electron microscopy showed enriched BM were compatible well with FG. No bacterial contamination or oncogenicity was observed after long-term culture. X-ray showed the repair effectiveness was significantly higher in BM+FG group and enriched BM+FG group than in simple FG group. Eight and 12 weeks after surgery, the Yang scores were significantly higher in enriched BM+FG group than in BM+FG group [(9.348±0.364évs.(7.984±0.229éìF=40.167ìP=0.001; (12.664±0.388)vs. (10.584±0.836é, F=20.3647ìP=0.004]. In addition, the Yang's scores at bone defects in BM+FG group and enriched BM+FG group were higher at the 12(th) week than in the 8(th) week. (F=36.004ìP=0.001; F=155.141ìP=0.000; respectively)The bone defects were repaired at varied degrees were histologically observed in BM+FG group and enriched BM+FG group during the observations.</p><p><b>CONCLUSION</b>Implantation of BM+FG or enriched BM+FG are effective in repairing old radial bone defects, while simple FG shows not such effect.</p>