Objective To evaluate the efficacy of "over iliac crest method" for ultrasound-guided posterior lumbar plexus block by comparing with manual palpation and sagittal positioning.Methods A total of 75 patients,aged 25-64 yr,weighing 42-90 kg,with body mass index of 17-32 kg/cm2,of American Society of Anesthesiologists physical status Ⅰ-Ⅲ,scheduled for elective lower extremity surgery under ultrasound-guided posterior lumbar plexus block combined with parasacral sciatic nerve block,were divided into 3 groups (n =25 each) using a random number table method:manual palpation group (group M),sagittal positioning group (group S) and "over iliac crest method" group (group O).Patients received ultrasound-guided posterior lumbar plexus block with in-plane technique using the corresponding positioning method in M,S and O groups.Successful blockade of each level was recorded at 30 min after injection.Time to determine the lumbar intervertebral space,puncture time for lumbar plexus block,the requirement for adjuvant drugs and block efficacy were recorded.The development of complications related to puncture and nerve block was also recorded.Results Compared with group M,the success rates of blockade at levels L1 and L2 were significantly increased,the success rates of blockade at levels L4 and L5 were decreased (P＜0.05),no significant difference was found in the success rate of blockade at level L3 (P＞0.05),the time to determine the lumbar intervertebral space was prolonged,and the requirement for adjuvant drugs was decreased during surgery in O and S groups,and the efficacy of block was significantly enhanced in group O (P＜0.05).Compared with group S,the success rates of blockade at levels L1 and L2 were significantly increased,the success rates of blockade at level L4 were decreased,the time to determine the lumbar intervertebral space was shortened (P＜0.05),and no significant change was found in the efficacy of block in group O (P＞0.05).There was no significant difference in the puncture time for lumbar plexus block between the three groups (P＞0.05).Complications related to puncture and nerve block were not found in three groups.Conclusion "Over iliac crest method" provides higher success rate and better efficacy than manual palpation and sagittal positioning when used for lumbar plexus block.

Aristolochic acid (AA), extracted from Aristolochiaceae plants, plays an essential role in traditional herbal medicines and is used for different diseases. However, AA has been found to be nephrotoxic and is known to cause aristolochic acid nephropathy (AAN).AA-induced acute kidney injury (AKI) is a syndrome in AAN with a high morbidity that manifests mitochondrial damage as a key part of its pathological progression. Melatonin primarily serves as a mitochondria-targeted antioxidant. However, its mitochondrial protective role in AA-induced AKI is barely reported. In this study, mice were administrated 2.5 mg/kg AA to induce AKI. Melatonin reduced the increase in Upro and Scr and attenuated the necrosis and atrophy of renal proximal tubules in mice exposed to AA. Melatonin suppressed ROS generation, MDA levels and iNOS expression and increased SOD activities in vivo and in vitro. Intriguingly, the in vivo study revealed that melatonin decreased mitochondrial fragmentation in renal proximal tubular cells and increased ATP levels in kidney tissues in response to AA. In vitro, melatonin restored the mitochondrial membrane potential (MMP) in NRK-52E and HK-2 cells and led to an elevation in ATP levels. Confocal immunofluorescence data showed that puncta containing Mito-tracker and GFP-LC3A/B were reduced, thereby impeding the mitophagy of tubular epithelial cells. Furthermore, melatonin decreased LC3A/B-II expression and increased p62 expression. The apoptosis of tubular epithelial cells induced by AA was decreased. Therefore, our findings revealed that melatonin could prevent AA-induced AKI by attenuating mitochondrial damage, which may provide a potential therapeutic method for renal AA toxicity.