BACKGROUND:Socket-shield technique can effectively maintain labial soft and hard tissues,but the incidence of postoperative complications such as exposure and displacement of root shield is relatively high.It is speculated that the root shield may be exposed and displaced due to excessive load after long-term function of dental implants. OBJECTIVE:Through three-dimensional finite element analysis,we aim to study the influence of varying root shield thicknesses on the stress distribution,equivalent stress peaks,and displacement in the root shield,periodontal ligaments,implant,and surrounding alveolar bone under normal occlusal loading.We also attempt to analyze the correlation between the thickness of the root shield and occurrence of mechanical events such as root shield exposure,displacement,and fracture. METHODS:Cone-beam CT data of a patient who met the indication standard of socket-shield technique for maxillary central incisor were retrieved from database.Reverse engineering techniques were used to build models of the maxillary bone and root shield,while forward engineering was used to create models for the implant components based on their parameters.Models depicting various root shield thicknesses(0.5,1.0,1.5,and 2.0 mm)were created using Solidworks 2022 software.ANSYS Workbench 2021 software was then used to simulate and analyze the effects of varying root shield thicknesses on stress distribution,equivalent stress peaks,and displacement of the root shields,periodontal ligaments,implants,and surrounding alveolar bone under normal occlusion. RESULTS AND CONCLUSION:(1)In all root shield models,the stress was concentrated on the palatal cervical side,both sides of the edges and the lower edge of the labial side.As the thickness of the root shield increased,the equivalent stress peak and displacement showed a decreasing trend.The 0.5 mm thickness model produced a stress concentration of 176.20 MPa,which exceeded the yield strength(150 MPa)of tooth tissue.(2)The periodontal ligament stress in each group was concentrated in the neck margin and upper region.With the increase of root shield thickness,the equivalent stress peak and displacement of periodontal ligament showed a decreasing trend.(3)Implant stress in all models was concentrated in the neck of the implant and the joint of the implant-repair abutment,and the labial side was more concentrated than the palatal side.With the increase of root shield thickness,the equivalent stress peak of the implant in the model showed an increasing trend.(4)In each group of models,stress of cortical bone concentrated around the neck of the implant and the periphery of the root shield,and the labial side was more concentrated than the palatal side.With the increase of the thickness of the root shield,the equivalent stress peak around the root shield decreased;the peak value of the equivalent stress of the bone around the neck of the implant showed an increasing trend.In the model,the stress of cancellous bone was mainly concentrated around the neck of the lip of the implant,the top of the thread,the root tip and the lower margin of the root shield,and the labial side was more concentrated than the palatal side.With the increase of the thickness of the root shield,the peak value of the equivalent stress of the bone around the root shield in the model showed a decreasing trend.The minimum principal stress of cortical bone in each group of models was concentrated around the neck of the implant,exhibiting a fan-shaped distribution.As the thickness of the root shield increased,the minimum principal stress of cortical bone showed an increasing trend.(5)These results indicate that different thicknesses of the root shield have different biomechanical effects.The root shield with a thickness of 0.5 mm is easy to fracture.For patients with sufficient bone width,the root shield with a thickness of 2.0 mm is an option to reduce the risk of complications such as root shield exposure,fracture,and displacement.Meanwhile,it should be taken into account to protect the periodontal ligament in the preparation process,and rounding treatments ought to be carried out on both sides and the lower edge of the root shield.

In-depth study of the components of polymyxins is the key to controlling the quality of this class of antibiotics.Similarities and variations of components present significant analytical challenges.A two-dimensional(2D)liquid chromatography-mass spectrometry(LC-MS)method was established for screening and comprehensive profiling of compositions of the antibiotic colistimethate sodium(CMS).A high concentration of phosphate buffer mobile phase was used in the first-dimensional LC system to get the components well separated.For efficient and high-accuracy screening of CMS,a targeted method based on a self-constructed high resolution(HR)mass spectrum database of CMS components was established.The database was built based on the commercial MassHunter Personal Compound Database and Library(PCDL)software and its accuracy of the compound matching result was verified with six known components before being applied to genuine sample screening.On this basis,the unknown peaks in the CMS chromatograms were deduced and assigned.The molecular formula,group composition,and origins of a total of 99 compounds,of which the combined area percentage accounted for more than 95％of CMS components,were deduced by this 2D-LC-MS method combined with the MassHunter PCDL.This profiling method was highly efficient and could distinguish hundreds of components within 3 h,providing reliable results for quality control of this kind of complex drugs.

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.

Diabetic retinopathy(DR)is a kind of microvascular disease caused by the long-term influence of diabetes mellitus(DM),and it is one of the main cause of global visual impairment and blindness.Its typical characteristics include microaneurysms,hard exudates,macular edema(DME)and neovascularization.Its pathogenesis is diverse,and the root cause is oxidative stress and advanced glycosylation end products.The nuclear red blood cell related factor 2(Nrf2)signa-ling pathway plays an important role in preventing various diseases.As one of the characteristics of DM,hyperglycemia will activate the generation of reactive oxygen species(ROS)in mitochondria.These oxidative stress factors activate the nucle-ar transcription factor κB pathway,becoming the main inducement of various complications of DM.This pathway will in-duce increased transcription of proinflammatory cytokines,including tumor necrosis factor-alpha,transforming growth fac-tor-beta and interleukin-1.The active ingredients of traditional Chinese medicine have significant antioxidant,anti-inflam-matory,anti-apoptotic and angiogenesis-promoting effects,and can block the progression of DR through various mecha-nisms.In this article,the research status of traditional Chinese medicine targeting the Nrf2 signaling pathway in the preven-tion and treatment of DR is reviewed to guide clinical and scientific research.

ObjectiveTo investigate the mechanism of Huangqin Tang （HQT） in regulating metabolic reprogramming during the inflammation-cancer transformation in colitis-associated colorectal cancer （CAC）. MethodsCAC mouse model was established using the carcinogen azoxymethane （AOM） combined with the inflammatory agent dextran sulfate sodium （DSS）. HQT treatment was adopted. Serum metabolomics analysis was performed at three stages （inflammation， proliferation， and tumor formation） using liquid chromatography-tandem mass spectrometry （LC-MS/MS） untargeted metabolomics coupled with multivariate statistical analysis to explore the mechanism of HQT intervention in metabolism in CAC. ResultsThe results revealed that HQT significantly reversed the disturbance of key metabolites in CAC mice. A total of 52， 67， and 45 differential metabolites were identified in the model group， compared to the normal group， during inflammation， proliferation， and tumor stages， respectively. Lactate， linoleic acid， oleic acid， elaidic acid， and betaine were characteristic metabolites persistently enriched throughout colitis-cancer transformation. Pathway enrichment analysis of differential metabolites showed that linoleic acid metabolism and arachidonic acid metabolism were the most significantly disturbed in CAC pathogenesis. The proliferation stage featured expanded amino acid metabolic networks， while the tumor stage uniquely exhibited two new pathways of nicotinate and nicotinamide metabolism and phosphoinositide metabolism. HQT exerted stage-specific regulatory effects： targeting arachidonic acid metabolism in the inflammation stage， correcting the dysregulation of choline-carnitine metabolism in the proliferation stage， and rescuing nicotinamide and tryptophan metabolic collapse in the tumor stage. ConclusionHQT exerts regulatory effects on metabolic disorders at various stages of the colitis-cancer transformation process， thereby effectively slowing the progression from colitis to cancer. The study also reveals the dynamic metabolic characteristics of colorectal "inflammation-cancer transformation，"providing new insights for research on the targeted mechanisms of traditional Chinese medicine in anti-tumor therapy based on metabolic reprogramming.

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.

Stem cell treatment may enhance erectile dysfunction (ED) in individuals with cavernous nerve injury (CNI). Nevertheless, no investigations have directly ascertained the implications of varying amounts of human umbilical cord-derived mesenchymal stem cells (HUC-MSCs) on ED. We compare the efficacy of three various doses of HUC-MSCs as a therapeutic strategy for ED. Sprague-Dawley rats (total = 175) were randomly allocated into five groups. A total of 35 rats underwent sham surgery and 140 rats endured bilateral CNI and were treated with vehicles or doses of HUC-MSCs (1 × 10 6 cells, 5 × 10 6 cells, and 1 × 10 7 cells in 0.1 ml, respectively). Penile tissues were harvested for histological analysis on 1 day, 3 days, 7 days, 14 days, 28 days, 60 days, and 90 days postsurgery. It was found that varying dosages of HUC-MSCs enhanced the erectile function of rats with bilateral CNI and ED. Moreover, there was no significant disparity in the effectiveness of various dosages of HUC-MSCs. However, the expression of endothelial markers (rat endothelial cell antigen-1 [RECA-1] and endothelial nitric oxide synthase [eNOS]), smooth muscle markers (alpha smooth muscle actin [α-SMA] and desmin), and neural markers (neurofilament [RECA-1] and neurogenic nitric oxide synthase [nNOS]) increased significantly with prolonged treatment time. Masson's staining demonstrated an increased in the smooth muscle cell (SMC)/collagen ratio. Significant changes were detected in the microstructures of various types of cells. In vivo imaging system (IVIS) analysis showed that at the 1 st day, the HUC-MSCs implanted moved to the site of damage. Additionally, the oxidative stress levels were dramatically reduced in the penises of rats administered with HUC-MSCs.
Male ; Animals ; Erectile Dysfunction/metabolism* ; Rats, Sprague-Dawley ; Mesenchymal Stem Cell Transplantation/methods* ; Rats ; Penis/pathology* ; Humans ; Disease Models, Animal ; Umbilical Cord/cytology* ; Peripheral Nerve Injuries/complications* ; Mesenchymal Stem Cells ; Nitric Oxide Synthase Type III/metabolism* ; Actins/metabolism* ; Nitric Oxide Synthase Type I/metabolism*

In-depth study of the components of polymyxins is the key to controlling the quality of this class of antibiotics. Similarities and variations of components present significant analytical challenges. A two-dimensional (2D) liquid chromatography-mass spectrometr (LC-MS) method was established for screening and comprehensive profiling of compositions of the antibiotic colistimethate sodium (CMS). A high concentration of phosphate buffer mobile phase was used in the first-dimensional LC system to get the components well separated. For efficient and high-accuracy screening of CMS, a targeted method based on a self-constructed high resolution (HR) mass spectrum database of CMS components was established. The database was built based on the commercial MassHunter Personal Compound Database and Library (PCDL) software and its accuracy of the compound matching result was verified with six known components before being applied to genuine sample screening. On this basis, the unknown peaks in the CMS chromatograms were deduced and assigned. The molecular formula, group composition, and origins of a total of 99 compounds, of which the combined area percentage accounted for more than 95% of CMS components, were deduced by this 2D-LC-MS method combined with the MassHunter PCDL. This profiling method was highly efficient and could distinguish hundreds of components within 3 h, providing reliable results for quality control of this kind of complex drugs.

Objective:To analyze the reoperation rate and causes during the early adoption phase of unilateral biportal endoscopy (UBE).Methods:The clinical data of 180 patients who underwent UBE performed by a single surgeon at Beijing Friendship Hospital, Capital Medical University from October 2021 to June 2023 were retrospectively analyzed. Clinical and imaging data of patients who underwent reoperation were collected to analyze the causes of reoperation, and the clinical efficacy of the reoperations was also followed up. Measurement data were expressed as mean ± standard deviation ( ± s), and t-test was used before and after treatment. Results:A total of 180 patients who underwent UBE were included in this study, of which 6 patients underwent reoperation, and the reoperation rate was 3.33%. Among them, 3 cases occurred in the first 90 surgeries and the other 3 occurred in the subsequent 90 surgeries. The causes of reoperation were as follows: recurrent lumbar disc herniation at the same segment postoperatively in 2 cases, insufficient decompression in 2 cases, disc herniation following isolated decompression in 1 case, and immediate postoperative perianal numbness in 1 case. The time between the initial surgery and reoperation ranged from 0 to 187 days, with an average of 63.3 days. The average follow-up time after reoperation was 18.3 months. The visual analogue scale (VAS) and Oswestry disability index (ODI) scores of the patients at the last follow-up were significantly improved compared with those before operation (VAS score of low back pain: 5.2 ± 1.7 before operation, 1.2 ± 0.8 at the last follow-up, P<0.001; VAS score of leg pain: 7.2 ± 1.5 before operation, 1.2 ± 1.2 at the last follow-up, P<0.001; ODI score: 67.3 ± 5.7 before operation, 20.2 ± 8.2 at the last follow-up, P<0.001). The postoperative modified MacNab scores were generally satisfactory (4 cases were rated as excellent, accounting for 66.7%; 2 cases were rated as good, accounting for 33.3%). Except for one patient who experienced dural injury during open revision surgery, there were no serious complications such as nerve damage. Conclusions:In the early stages of UBE surgery, recurrent lumbar disc herniation and inadequate decompression are the primary reasons for reoperation, typically occurring within the first three months postoperatively. Reoperation does not significantly increase the risk of nerve injury. Enhanced early postoperative follow-up is recommended. For symptomatic patients, a second surgery with thorough decompression can yield satisfactory treatment outcomes.