Objective:To study the stress distribution dur i ng clenching and rigid internal fixation(RIF)of mandibular symphysis fracture. Methods:ANSYS software was used to establish the models of mandi bular symphysis fracture and the fracture treatment treat with RIF.The stress di stribution of mandibular symphysis fracture under different conditions were then analysed during different period of bone healthing. The value of stress shieldi ng rate was used to represent the level of stress shielding effects.Resu lts:The stress shielding rate decreased with the progression of fracture healing.The stress shielding rate produced by double plates fixation was higher than that by single plate.Stress shielding rate in the mandible fixed with tita nium plate was lower than that with steel plate.Conclusion:Minip late rigid internal fixation system may produce stress shielding effects when it is used to treat mandibular symphysis fractures. Stress shielding effects are a ffected by the attribute, the shape and the position of the plate.

Optimization of sedation depth has become one of hot spots for critical care medicine research.Previous multiple studies have demonstrated that deep sedation is associated with poor outcomes in patients with mechanical ventilation.But unnecessary deep sedation remained not rare in our clinical practices owing to complex reasons (partially unknown).Maintaining light rather than deep sedation stragey for patients with mechanical ventilation,therefore,was highly recommended.Meanwhile,it was concerned that the depth of sedation was probably proscribed inappropriately in some of lightly sedated patients largely due to lack of well-predefined contraindications,which even likely increased risk of adverse events in our clinical practices.In addition,increasing publications updated the impacts of analgesia/sedation on immune,gastrointestinal and neural-muscular function in the patients with chronic critical illness,a highly concerned critically ill population.Based on available data,less sedatives and opioids were suggested for these patients.Moreover,eCASH concept,a patient-centered,adequate analgesia and light sedation based and humanistic care strengthened comprehensive management strategy was currently proposed to improve the long-term outcomes for patients with mechanical ventilation.It provided us valuable information,in either optimization of clinical practices or research interests,on promoting our medical behaviors and cognition in order to improve patient comfort,safety and clinical outcomes.However,future high-quality clinical researches are needed to verify its feasibility and validity.

Objective To analyze the causes of rhabdomylysis (RM), pathogenetic mechanisms and possible effective interventions for secondary multiple organ dysfunction syndrome (MODS) caused by RM. Methods causes of RM, clinical manifestations, severity of disease evaluated by APACHE Ⅱ and Marshall MODS Score, results of laboratory, clinical interventions and outcome were analyzed in all three MODS cases secondary to RM. Results The specific causes of RM were not clear. However, persistent acute twitch and hyperthermia occurred very early in all three cases. Plasma CK was increased 50 fold over the normal level. Number of injured organs was 7, 4 and 6, respectively. Marshall MODS score ranged from 15 to 21. APACHE Ⅱ scores were greater than 20 in all cases. One patients survived, the other two died. CRRT started early had been shown to be beneficial to decrease the markedly elevated plasma CK, CK-Mb, ALT, ALT and LDH. Conclusion Although the mechanism of RM with secondary MODS has not been elucidated yet, deep sedation as well as effective hypothermia to control acute twitch and hyperthermia should be the essential interventions to attenuate further organ injury. Additionally, based on effective advanced life support, CRRT started early could be an important therapy for MODS secondary to RM.

Causal inference research is a causal test designed to assess the impact of exposures on outcomes.Both experimental and observational studies can be used to examine causal associations between exposure factors and outcomes. Experimental studies are sometimes limited by factors such as ethics or experimental conditions. Observational studies account for a large proportion in clinical studies, but the effectiveness and research value of observational studies will be affected if the design of observational studies is not rigorous and the confounding factors are not well controlled.The Guidelines for controlling confounding factors and reporting results in causal inference studie formulated by a special group of 47 editors from 35 journals from all over the world provide good guidance to researchers. This article interprets the guidelines and hopes to provide help for clinical researchers.

Objective To biomechanically study the fixation stability of different numbers and shapes of the titanium miniplates (L-shaped and straight four-hole miniplates) in the treatment of maxillary LeFortⅠ fracture by using three-dimensional finite element method so as to provide reference for clinical treatment of the fractures. Methods Three-dimensional finite element model of maxillary LeFortⅠ fracture was established with four kinds of rigid internal fixation (RIF) methods to calculate the stress of the maxilla and the RIF as well as the displacement of the fracture segment under three kinds of occlusion.Then, the fixation stability of different methods was compared. Results Under the same occlusion condition, the decreasing order of the displacement of the fracture segment was the L-shaped plate fixation at both buttress of the maxillary and nasal maxillary zygomatic, the straight four-hole miniplates fixation at both buttress of the maxillary and nasal maxillary zygomatic, the L-shaped plate fixation at the zygomatic maxillary buttress and the L-shaped plate fixation at naso-maxillary buttress. Under the same fixation method, the decreasing order of the displacement of the fracture segment was molar occlusion, premolar oeclusion and incisor occlusion. Conclusions The fixation stability of the L-shaped plate fixation is better than the straight four-hole miniplate fixation for the treatment of LeFortⅠ fracture. Fixation at the zygomaticmaxillary buttress is better than at the naso-maxillary buttress. Use of only two miniplates to fix the LeFort Ⅰ fracture may not be stable. Molar occlusion is not good for fracture healing.

Objective To set up the 3D-finite element(FE)model of normal acetabulum-cartilage-femoral head,so that to provide an effective model for biomechanical analysis of femoral head.Methods(1)The hip joint in one healthy adult male volunteer was scanned by MRI at coronal section.The 3D reconstruction model of acetabulum-cartilage-femoral head was constructed with MATLAB and ANSYS software.(2)The 3D orthotropy finite element model of the acetabulum-cartilage-femoral head was constructed by givig the corresponding material parameters to the different structures of the model of acetabulum-cartilage-femoral head and divided into networks through ANSYS software.(3)The standing status was imitated on the model to set boundary condition and loading and then calculated.The effect of the model was evaluated in comparison with that of literature.Results A 3D orthotropy FE model of acetabulum-cartilage-femoral head was established successfully,including 89 961 points of 448 159 units.The maximal displacement was on the femoral head,and the maximal Von Mises stress was on the femur neck.The stress analysis was the same as the results of literature and the actuality.Conclusion A 3D orthotropy FE model of acetabulum-cartilage-femoral head can be setup based on MRI images,which can provide a reasonable and effective model for biomechamical analysis of femoral head.

Objective:To observe the efficacy and safety of individual dose of intravitreal conbercept (IVC) in the treatment of retinopathy of prematurity (ROP) before type 1 threshold.Methods:A retrospective case study. From January to July, 2019, 23 cases (46 eyes) of children with type 1 pre-threshold ROP were included in the study. Among them, 14 cases (28 eyes) were male and 9 cases (18 eyes) were female. The mean gestational age at birth was 28.06±1.73 weeks. The average birth weight was 1.14±0.19 kg. The mean corrected gestational age was 34.38±1.41 weeks at the time of first intravitreal injection of IVC. The axial length (AL) of children was measured by A-mode ultrasound before IVC for the first time. According to the calculation of AL, the corresponding injection dose range was 14.23-16.19, 16.20-17.57, 17.58-18.63 mm and the injection dose of IVC was 0.015, 0.020, 0.025 ml (including IVC was 0.15, 0.20, 0.25 mg, respectively). The first IVC dose was 0.015 ml. On the first day before IVC and on the first and seventh days after IVC, 2 ml of arterial blood was taken from children, serum vascular endothelial growth factor (VEGF) concentration was detected. The follow-up time after treatment was ≥1 year. After one year of follow-up, the effective rate and recurrence rate of IVC for the first time were tested by χ2 tests. The short-term changes of injection times, injection intervals, retinal vascularization time and serum VEGF concentration in children were tested by t test. Results:Retinal neovascularization subsided and vascular buckling decreased in all eyes. Iris neovascularization subsided, 1-3 weeks after IVC for the first time. Within one year after the first IVC, 16 eyes underwent IVC twice with or without new blood vessels at the junction of the vascular area. The average corrected gestational age was 40.56±3.81 weeks. The injection dose of IVC was 0.015 ml and 0.020 ml for 2 eyes and 14 eyes, respectively.The mean interval from IVC for the first time was 40.89±8.99 days. Of the 16 eyes who underwent IVC twice, 8 eyes showed neovascularization again in the retinal area with or without blood vessels. The average corrected gestational age was 43.00±1.41 weeks. The injection dose of IVC was 0.020 ml and 0.025 ml for 3 eyes and 5 eyes, respectively. The mean interval of the second IVC was 28.60±6.07 days. The mean interval from the first IVC was 69.20±12.40 days. At the end of follow-up, all eyes were treated effectively (100%, 46/46). The mean time of retinal vascularization was 46.31±3.42 weeks. The average number of injections was 1.52±0.76. On the first day before IVC and on the first and seventh days after IVC, the average serum VEGF concentrations were 111.21±148.71, 25.60±27.71 and 42.99±38.01 pg/ml, respectively. Serum VEGF concentration was significantly lower than that before IVC on the 1st and 7th day after IVC ( Z=-4.054, -2.779; P<0.05). Serum VEGF concentration was higher 7 days after IVC than 1 day after IVC, and the difference was statistically significant ( Z=-2.505, P<0.05). All eyes were not treated by laser photocoagulation or vitrectomy. No eye complications such as lens opacification, endophthalmitis and retinal detachment related to drugs or treatment methods were found in all patients. Conclusion:Intravitreal injection of individualized dose of IVC is effective in the treatment of type 1 pre-threshold ROP. Seven days after treatment, serum VEGF concentration of patients’serum decreases.

Objective: To study the effect of different wetness degrees in the root canal on the canal sealing. Methods: 160 root canal prepared single rooted teeth were divided into 4 groups (n = 40) by the root canal wetness degree (water content, V): (1) 0. 250 ～0. 299, (2) 0. 300 ～ 0. 599, (3) 0. 600 ～ 0. 899 and (4) 0. 900 ～ 1. 199 respectively. 80 teeth were divided into 4 groups (n = 20) for dye leakage test and another 80 for bacterial microleakage test. Zinc oxide paste (ZOP) and AH-Plus (AH-P) with vertical condensation of warm gutta-percha were respectively used to seal the canals in each group of the samples (n = 10) . The length of in vitro tooth dye penetration was measured by stereomicroscope; the time (days) of turbidity in the bacterial leakage model observed and compared. Results: Of all the canals sealed by ZOP or AH-P with the increase of the wetness the dye infiltration length increased significantly (P ＜0. 05) and the days in which the faecal intestine ball infiltrated into the lower chamber of the model was gradually decreased (P ＜0. 05) . Conclusion: The increase of root canal moisture may reduce the sealing of the root canal.

The management of healthcare services for the suspected cases in non-designated hospitalsis a serious concern in controlling coronavirus disease 2019 (COVID-19) epidemic. Owing to the complexity of care providers, large requirement of medical supplies as well as the possible needs off frequent transfers, the major difficulty is preventing the coronavirus from spreading while caring the suspected critical cases before the 2019 novel coronavirus ribonucleic acid test results are reported. For the purpose of enhancing the prevention of the propagation of COVID-19, this article puts emphasis on the following aspects in non-designated hospital Peking University Third Hospital: preparatory procedures of receiving critical suspected patients, the management of medical personnel during the waiting session of RNA test results, the delivering procedures of testing samples, the management of referred medical wastes, daily operations including the cleaning and sanitizing of caring units and the management of related patients after the testing session.

Objective:To investigate the malignant potential of histopathological class B3 and B5a lesions by ultrasound-guided core needle biopsy (CNB).Methods:Retrospective analysis of the histopathological results of 712 breast lesions that successively underwent CNB process and surgical resection in the Shanghai General Hospital from January 2018 to December 2022, of which 47 lesions were reported as class B3 and 70 lesions as class B5a.Results:CNB identified 47 category B3 lesions, comprising 19 cases of atypical ductal hyperplasia, 17 papillary lesions, 8 phyllodes tumors, and 3 complex sclerosing lesions. Of these cases, surgical pathology was in full agreement with CNB pathology in 27 instances, indicating a concordance rate of 57.4% (27/47) and an inconsistency rate of 42.6% (20/47). Out of the 20 inconsistent cases, 70.0% (14/20) were upgraded based on the findings from the surgical pathology.Specifically, 4 cases of atypical ductal hyperplasia and 2 cases of intraductal papilloma were upgraded to invasive breast cancer (B5b) after surgery. Among the 4 cases with puncture pathology indicating atypical ductal hyperplasia and one complex sclerosing lesion, these five lesions were upgraded to ductal carcinoma in situ (B5a) after surgery. Two puncture pathologies were diagnosed as atypical ductal hyperplasia, and these were upgraded to ductal carcinoma in situ with microinvasion (B5b) after surgery. One puncture pathology indicated a borderline phyllodes tumor, and this was upgraded to malignant phyllodes tumor (B5b) after surgery. And 30.0% (6/20) resulted in downgrade after surgery, specifically 4 cases of atypical ductal hyperplasia, which were downgraded to breast adenopathy (B2). Of these, 1 puncture pathology was identified as atypical ductal hyperplasia and one as a borderline phyllodes tumor, which were both downgraded to fibroadenoma (B2). Seventy lesions were diagnosed as B5a lesions by CNB pathology, with 28 of them showing complete concurrence with the surgical pathology, a concordance rate of 40.0% (28/70), and an inconsistency rate of 60.0% (42/70). Of the 42 cases with discrepancies, all 42 were upgraded, yielding an upgrading rate of 100% (42/42). Of these, 21 were upgraded to ductal carcinoma in situ with microinvasion (B5b) and 21 to invasive breast cancer (B5b).Conclusions:Lesions with CNB pathology in categories B3 and B5a have a high rate of postoperative escalation. B3 and B5a lesions should be treated with considerable care, especially atypical ductal hyperplasia, which should be surgically resected, and CNB examination should be performed twice if necessary.