Melatonin inhibits paraquat-induced cell death in bovine preimplantation embryos.

Preimplantation embryos are sensitive to oxidative stress-induced damage that can be caused by reactive oxygen species (ROS) originating from normal embryonic metabolism and/or the external surroundings. Paraquat (PQ), a commonly used pesticide and potent ROS generator, can induce embryotoxicity. The present study aimed to investigate the effects of melatonin on PQ-induced damage during embryonic development in bovine preimplantation embryos. PQ treatment significantly reduced the ability of bovine embryos to develop to the blastocyst stage, and the addition of melatonin markedly reversed the developmental failure caused by PQ (20.9% versus 14.3%). Apoptotic assay showed that melatonin pretreatment did not change the total cell number in blastocysts, but the incidence of apoptotic nuclei and the release of cytochrome c were significantly decreased. Using real-time quantitative polymerase chain reaction analysis, we found that melatonin pre-incubation significantly altered the expression levels of genes associated with redox signaling, particularly by attenuating the transcript level of Txnip and reinforcing the expression of Trx. Furthermore, melatonin pretreatment significantly reduced the expression of the pro-apoptotic caspase-3 and Bax, while the expression of the anti-apoptotic Bcl-2 and XIAP was unaffected. Western blot analysis showed that melatonin protected bovine embryos from PQ-induced damage in a p38-dependent manner, but extracellular signal-regulated kinase (ERK) and c-JUN N-terminal kinase (JNK) did not appear to be involved. Together, these results identify an underlying mechanism by which melatonin enhances the developmental potential of bovine preimplantation embryos under oxidative stress conditions.

[Navigated percutaneous placement of iliosacral screws using intra-operative three-dimensional imaging].

OBJECTIVE: To investigate the effect of a new technique of navigated percutaneous placement of iliosacral screws using intra-operative three-dimensional (3D) imaging. METHODS: Sixteen patients with hip fracture were placed in supine position. After the reference marker was fixed on the iliac crest, a 3-D C-arm navigation system was used intra-operatively to obtain 3D images that were transferred to the navigation system by an automatic. Registration process to calculate the length of screw and direction to insert it. A navigated pointer defined the entry point, while navigated percutaneous drilling was done accordingly with a navigated drill bit in combination with a navigated drill sleeve under permanent dynamic control on the navigation screen without further intra-operative fluoroscopic imaging. A control intra-operative 3D scan was used to observe the position of the screws, while for didactic reasons another postoperative CT scan was done. RESULTS: Twenty screws were successfully inserted into the first sacral vertebral bodies of the 16 patients. No additional intra-operative and postoperative complications occurred. The average operation time was 80 minutes and the average intra-operative radiation time was 1.13 minutes. Four patients underwent bilateral iliosacral fixation with longer operation time (152 minutes) and radiation time (1.56 minutes). The post-operative 3D scanning showed good results. No screws penetrated into the sacral canal or foramen. The reduction of fracture or dislocation and the position of iliosacral screws were all judged satisfactory. CONCLUSION: Compared with the conventional fluoroscopy method, navigated percutaneous placement of iliosacral screws under intra-operative 3D imaging reduces the radiation time and improves the accuracy. It is feasible and useful though there are some disadvantages such as the inferior image quality compared to CT scan, prolonged operation time and higher overall cost.