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Background: Burn wounds continue to worsen after initial injury in a process known as burn conversion, which lasts about 3-5 days. It causes burn wounds to enlarge and deepen, leading to greater morbidity. Apoptosis is one of the factors contributing to the conversion of the zone of stasis into the zone of coagulation. Suppression of apoptosis has been associated with reducing burn conversion. Connexin 43 (Cx43) gap junctions facilitate the spread of apoptotic signals from dying cells to healthy neighbouring cells in injured tissues through the bystander effect., Objectives: The study is to understand the role of Cx43 in burn conversion., Methods: In our study, 15 burn tissue samples were arranged into three groups as early (beginning of burn conversion), intermediate (extensive burn conversion) and late (established burn conversion) burns., Results: We found a striking increase in the amount of Cx43 protein expressed in the dermal fibroblasts (identified with heat shock protein 47 (HSP47) staining) in the zone of stasis in early and intermediate burns. These dermal fibroblasts also express high levels of cleaved-Caspase 3 indicating on-going apoptosis., Conclusions: Our findings suggest that elevation of Cx43 may play an active role in burn conversion spreading apoptosis in the early and intermediate burn wound., (Copyright © 2020 Elsevier Ltd and ISBI. All rights reserved.)

Background: Surgical stabilization of rib fractures is an established form of treatment for complex rib fractures. Plate fixation with bicortical screws placement can cause injury to intra-thoracic organs and pleural irritation from protruding screw tips. The aim of this study is to compare the biomechanical properties of monocortical and bicortical plate fixation for rib fractures using a locking plate system., Methods: Ten pairs of fresh-frozen cadaveric ribs were harvested. Native ribs were mounted onto a biomechanical tester and statically loaded to failure to induce a rib fracture. The native stiffness of the rib was measured. Next, the ribs were stabilized using the Synthes MatrixRIB (Johnson & Johnson, USA) locking plate. Left-sided ribs were fixed in a bicortical manner and right-sided ribs were fixed in a monocortical manner. The repaired ribs were subjected to cyclic loading of 50,000 cycles between 2 to 6 N to simulate physiological respiration, followed by static loading at a rate of 10 N/min until failure. The pre and post-repaired stiffness were measured. A high-speed camera was used to record the mechanism of failure., Results: One left-sided rib was omitted from the study because the fracture occurred at the drill hole site. Left-sided ribs demonstrated a mean native stiffness of 10.0 N/mm (SD 3.71) and right-sided 11.92 N/mm (SD 3.57). After plate fixation, pre and post cyclic stiffness was 3.32 N/mm (SD 1.21) and 4.41 N/mm (SD 3.29) for the bicortical group; 3.14 N/mm (SD 1.24) and 3.91 N/mm (SD 1.98) for the monocortical group. There is no statistical difference found between the two groups (P=0.872)., Conclusions: Our results show that there is no difference in stability between monocortical and bicortical fixation for rib fractures using a locking plate system. Monocortical fixation is recommended to avoid potential complications., Competing Interests: Conflicts of Interest: The authors have no conflicts of interest to declare., (2019 Journal of Thoracic Disease. All rights reserved.)

Background: The reconstruction of extensive tracheal defects is an unresolved problem. Despite decades of research, a reliable and practical substitute remains to be found. While there have been clinical reports of successful long-segment tracheal reconstruction, reproducibility and widespread applicability of these techniques have yet to be achieved. Large animals such as the dog, pig, sheep, and goat have comparable tracheal morphology and physiology to humans making them useful preclinical models to screen potential therapeutic strategies., Materials and Methods: The literature was reviewed to identify large animal models commonly used for tracheal reconstruction. A systematic search of PubMed and EMBASE was performed for large animal studies reporting on the reconstruction of long-segment tracheal and carinal defects. Fifty-seven studies were identified for analysis., Results: There is no standard large animal model available for tracheal research. In recent years, livestock species have gained favor over dogs as animal models in this field. The minimum requirements for successful tracheal replacement are rigidity, vascularity, and epithelial lining. Early attempts with synthetic prostheses were met with disappointing results. An autologous tracheal substitute is ideal but hindered by limited donor site availability and the lack of a dominant vascular pedicle for microsurgical reconstruction. Although tracheal allotransplantation enables like-for-like replacement, there are unresolved issues relating to graft vascularity, immunosuppression, and graft preservation. Tissue engineering holds great promise; however, the optimal combination of scaffold, cells, and culture conditions is still indeterminate., Conclusions: Despite impressive advances in tracheal reconstruction, a durable substitute for extended tracheal defects continues to be elusive., (Copyright © 2018 Elsevier Inc. All rights reserved.)