ObjectiveTo explore the effects of serine hydroxymethyltransferase 1 （SHMT1） rs1979277 polymorphisms on pharmacokinetic characteristics and clinical prognosis of methotrexate （MTX） in children with acute lymphoblastic leukemia （ALL）. MethodsMatrix-assisted laser desorption/ionization time of flight mass spectrometry was used for SHMT1 rs1979277 genotyping in children with ALL . Clinical data including serum MTX concentrations， incidences of adverse events， and ALL relapse after chemotherapy with MTX were collected. The associations of SHMT1 rs1979277 G>A genotypes with dose-adjusted serum concentrations （C/D ratios）， adverse events of MTX， and relapse were analyzed. The associations between rs1979277 genotypes and SHMT1 expression were explored based on Bioinformatics methods. ResultsAmong the 146 children with ALL included， the rs1979277 GG homozygous genotype accounted for 85.62% （125/146）， while the GA heterozygous genotype accounted for 14.38% （21/146）. The frequency of the G allele was 92.81% （271/292）， while the A allele was only 7.19% （21/292）. Children with the GG homozygous genotype had higher median C/D ratios of MTX in 24 h ［12.06 （μmol·m²）/（L·g）］ and higher relapse rates （12.80%） than those in GA heterozygous genotype carriers ［10.96 （μmol·m²）/（L·g）， and 9.52%， respectively］. However， none of the above differences were statistically significant （all P>0.05）. The incidences of respiratory （19.05%） and liver disorders （33.33%） in children with the GA heterozygous genotype were significantly higher than those in GG homozygous genotype carriers （4.00% and 12.00%， respectively， P<0.05）. There were no statistically significant differences in the incidences of other adverse events. Bioinformatics analysis showed that the rs1979277 A allele was significantly associated with higher SHMT1 expression in multiple tissues， such as the tibial artery， pancreas， and adrenal gland （P<0.05）. ConclusionSHMT1 rs1979277 GA genotype may be a risk factor for respiratory and liver disorders in ALL children treated with MTX.

Objective:To analyze the learning curve of TiRobot-assisted lumbar pedicle screw fixation (LPSF) by cumulative sum (CUSUM) test method.Methods:The clinical data of 50 patients who underwent TiRobot-assisted LPSF from January 2020 to December 2022 in Beijing Friendship Hospital, Capital Medical University were retrospectively analyzed. CUSUM analysis and learning curve fitting were performed with robot usage time as the main indicator with the time for each step refined (robot registration time, path planning time and guide wire placement time), to select the best learning curve fitting model with the R2 value closest to 1. Using the turning point of the learning curve as the boundary, the learning curve was divided into two stages as learning stage and maturity stage, and then the observation indexes were compared between the two stages. Results:All 50 patients successfully completed the surgery without perioperative complications, with a total of 244 pedicle screws implanted. The total robot usage time and robot registration time showed a gradually decreasing trend with the increase of case number, and the learning curves were successfully fitted and reached their peaks at the seventeenth and thirteenth cases respectively. The entire learning process was divided into learning stage (17 cases) and maturity stage (33 cases) based on the turning point of the learning curve of total robot usage time. The path planning time and guide wire placement time did not show significant changes with the increase in the case number. The total robot usage time, robot registration time and the intraoperative blood loss in the learning stage were significantly higher than those in the maturity stage: (35.35 ± 1.58) min vs. (30.61 ± 0.43) min, (20.83 ± 1.56) min vs. (14.94 ± 0.29) min and 400 (150, 500) ml vs. 200 (110, 300) ml, the guide wire placement time of per screw was significantly lower than that in the maturity stage: 2.00 (1.83, 2.34) min/screw vs. 2.33 (2.13, 2.69) min/screw, and there were statistical differences ( P<0.05 or <0.01). There were no statistical difference in the path planning time, path planning time of per screw, guide wire placement time and the accuracy of screw placement between two stages ( P>0.05). Conclusions:TiRobot-assisted LPSF is a new technology with safety and effectiveness, and it has a relatively short learning curve. To achieve technological maturity, at least 17 surgeries are required with accumulated experience, and the robot registration is the main step of the learning process. After reaching maturity stage, the robot usage time is significantly shortened and intraoperative trauma is significantly reduced while the relatively high screw placement accuracy is ensured.

Objective:To analyze the learning curve of TiRobot-assisted lumbar pedicle screw fixation (LPSF) by cumulative sum (CUSUM) test method.Methods:The clinical data of 50 patients who underwent TiRobot-assisted LPSF from January 2020 to December 2022 in Beijing Friendship Hospital, Capital Medical University were retrospectively analyzed. CUSUM analysis and learning curve fitting were performed with robot usage time as the main indicator with the time for each step refined (robot registration time, path planning time and guide wire placement time), to select the best learning curve fitting model with the R2 value closest to 1. Using the turning point of the learning curve as the boundary, the learning curve was divided into two stages as learning stage and maturity stage, and then the observation indexes were compared between the two stages. Results:All 50 patients successfully completed the surgery without perioperative complications, with a total of 244 pedicle screws implanted. The total robot usage time and robot registration time showed a gradually decreasing trend with the increase of case number, and the learning curves were successfully fitted and reached their peaks at the seventeenth and thirteenth cases respectively. The entire learning process was divided into learning stage (17 cases) and maturity stage (33 cases) based on the turning point of the learning curve of total robot usage time. The path planning time and guide wire placement time did not show significant changes with the increase in the case number. The total robot usage time, robot registration time and the intraoperative blood loss in the learning stage were significantly higher than those in the maturity stage: (35.35 ± 1.58) min vs. (30.61 ± 0.43) min, (20.83 ± 1.56) min vs. (14.94 ± 0.29) min and 400 (150, 500) ml vs. 200 (110, 300) ml, the guide wire placement time of per screw was significantly lower than that in the maturity stage: 2.00 (1.83, 2.34) min/screw vs. 2.33 (2.13, 2.69) min/screw, and there were statistical differences ( P<0.05 or <0.01). There were no statistical difference in the path planning time, path planning time of per screw, guide wire placement time and the accuracy of screw placement between two stages ( P>0.05). Conclusions:TiRobot-assisted LPSF is a new technology with safety and effectiveness, and it has a relatively short learning curve. To achieve technological maturity, at least 17 surgeries are required with accumulated experience, and the robot registration is the main step of the learning process. After reaching maturity stage, the robot usage time is significantly shortened and intraoperative trauma is significantly reduced while the relatively high screw placement accuracy is ensured.

Objective:To investigate various clinical treatment measures for thoracolumbar fractures and provide new diagnosis and treatment methods.Methods:The case data of 5 patients(3 males, 2 females, and the age ranged from 39 to 59 years with an average of 51 years) with thoracolumbar fractures were treated with Waveflex semi-rigid internaI fixation system from May 2020 to December 2021 were retrospectively analyzed, imaging indexes and clinical effects were followed up, and analyzed and summarized in combination with relevant literatures.Results:The operations of all 5 patients were successfully completed, and the follow-up period was 6 months. At the last follow-up, the internal fixation position was good, the height of the injured vertebra was maintained satisfactorily, and the clinical effect was satisfactory.Conclusion:Waveflex semi-rigid internal fixation system combines the advantages of fusion and non-fusion, providing a new idea for the treatment of thoracolumbar fractures, but its long-term effect still needs further follow-up.

Objective:To observe the morphological characteristics of lungs in patients with critical corona virus disease 2019 (COVID-19), and to analyze the clinical-pathological relationship.Methods:Two critical patients with COVID-19 who died in Beijing You′an Hospital, Capital Medical University on February 13 and 14, 2020, respectively, were examined by bilateral lungs biopsy. The obtained samples were dehydrated, paraffin embedded, sectioned, stained with hematoxylin-eosin as routine methods, and then observed under light microscope.Results:The pulmonary morphology changes of patients with COVID-19 showed diffuse alveolar damage. Case one was an elderly patient with underlying diseases and her lesions were mainly exudation and hyaline membrane formation, which showed an acute exudation stage of diffuse alveolar damage. Case two was a patient without underlying diseases and his pathological changes were diffuse inflammatory cell infiltration, extensive fibrosis of alveolar wall, filling of necrotizing inflammatory cellulosic exudate in alveolar airspace, extensive destruction of alveoli and pulmonary consolidation, which was characterized by organized stage of diffuse alveolar damage complicated with bacterial pneumonia. The injury of paracronchial submucosal gland was not observed in the two patients.Conclusions:Diffused alveolar damage is the main pathological feature of critical COVID-19. Diffused alveolar damage can induce or aggravate the underlying diseases of elderly patients in the early stage. Extensive destruction of alveoli, pulmonary consolidation and secondary infection are the main causes of respiratory failure in the late stage.