The lumbar intervertebral disc exhibits a complex physiological structure with interactions between various segments, and its components are extremely complex. The material properties of different components in the lumbar intervertebral disc, especially the water content (undergoing dynamic change as influenced by age, degeneration, mechanical loading, and proteoglycan content) - critically determine its mechanical properties. When the lumbar intervertebral disc is under continuous pressure, water seeps out, and after the pressure is removed, water re-infiltrates. This dynamic fluid exchange process directly affects the mechanical properties of the lumbar intervertebral disc, while previous isotropic modeling methods have been unable to accurately reflect such solid-liquid phase behaviors. To explore the load-bearing mechanism of the lumbar intervertebral disc and establish a more realistic mechanical model of the lumbar intervertebral disc, this study developed a solid-liquid biphasic, fiber-reinforced finite element model. This model was used to simulate the four movements of the human lumbar spine in daily life, namely flexion, extension, axial rotation, and lateral bending. The fluid pressure, effective solid stress, and liquid pressure-bearing ratio of the annulus fibrosus and nucleus pulposus of different lumbar intervertebral discs were compared and analyzed under the movements. Under all the movements, the fluid pressure distribution was closer to the nucleus pulposus, while the effective solid stress distribution was more concentrated in the outer annulus fibrosus. In terms of fluid pressure, the maximum fluid pressure of the lumbar intervertebral disc during lateral bending was 1.95 MPa, significantly higher than the maximum fluid pressure under other movements. Meanwhile, the maximum effective solid stress of the lumbar intervertebral disc during flexion was 2.43 MPa, markedly higher than the maximum effective solid stress under other movements. Overall, the liquid pressure-bearing ratio under axial rotation was smaller than that under other movements. Based on the solid-liquid biphasic modeling method, this study more accurately revealed the dominant role of the liquid phase in the daily load-bearing process of the lumbar intervertebral disc and the solid-phase mechanical mechanism of the annulus fibrosus load-bearing, and more effectively predicted the solid-liquid phase co-load-bearing mechanism of the lumbar intervertebral disc in daily life.
Humans ; Finite Element Analysis ; Intervertebral Disc/physiology* ; Lumbar Vertebrae/physiology* ; Weight-Bearing/physiology* ; Biomechanical Phenomena ; Stress, Mechanical ; Computer Simulation ; Models, Biological

Objective:To construct an indicator system for entrustable professional activities (EPAs) in the general practice enhancement stage of pediatric specialist physician training.Methods:A draft indicator system for EPAs in the general practice enhancement stage of pediatric physician training was developed through core EPAs working group discussion, literature review, nominal group discussion, and expert consultation. Subsequently, the indicator system was preliminarily implemented and revised.Results:The core EPAs working group consisted of nine specialist physician trainers. In the initial brainstorming stage, a "potential list" of 30 activities was established. After literature review and collation, the draft indicator system included eight EPAs. Through nominal group discussion, the connotation of the draft was enriched, and the importance of the EPAs was ranked and modified. Finally, through expert consultation, the EPAs for the general practice enhancement stage of pediatric specialist physician training were determined. These included basic operations for the treatment of critically ill children, identification and management of critical illnesses, referral of critically ill children, perioperative management, in-hospital consultation, medical and teaching management and system improvement, doctor-patient communication and dispute handling, and response to public health events. During the preliminary implementation stage, a total of nine specialist physicians who participated in the training were evaluated. Based on the problems found in the pre-evaluation, the indicators of EPAs were revised, and a corresponding curriculum training system was developed.Conclusions:Through multiple rounds of nominal group discussion and expert consultation, the indicator system for EPAs in the general practice enhancement stage of pediatric specialist physician training was formulated. The system was preliminarily implemented and revised, and a curriculum system was constructed.

Objective:To construct an indicator system for entrustable professional activities (EPAs) in the general practice enhancement stage of pediatric specialist physician training.Methods:A draft indicator system for EPAs in the general practice enhancement stage of pediatric physician training was developed through core EPAs working group discussion, literature review, nominal group discussion, and expert consultation. Subsequently, the indicator system was preliminarily implemented and revised.Results:The core EPAs working group consisted of nine specialist physician trainers. In the initial brainstorming stage, a "potential list" of 30 activities was established. After literature review and collation, the draft indicator system included eight EPAs. Through nominal group discussion, the connotation of the draft was enriched, and the importance of the EPAs was ranked and modified. Finally, through expert consultation, the EPAs for the general practice enhancement stage of pediatric specialist physician training were determined. These included basic operations for the treatment of critically ill children, identification and management of critical illnesses, referral of critically ill children, perioperative management, in-hospital consultation, medical and teaching management and system improvement, doctor-patient communication and dispute handling, and response to public health events. During the preliminary implementation stage, a total of nine specialist physicians who participated in the training were evaluated. Based on the problems found in the pre-evaluation, the indicators of EPAs were revised, and a corresponding curriculum training system was developed.Conclusions:Through multiple rounds of nominal group discussion and expert consultation, the indicator system for EPAs in the general practice enhancement stage of pediatric specialist physician training was formulated. The system was preliminarily implemented and revised, and a curriculum system was constructed.

Objective:To investigate the efficacy and safety of recombinant tissue plasminogen activator (rt-PA) in patients with wake-up ischemic stroke (WUIS) of anterior circulation non-major arteries.Methods:Sixty-seven patients with WUIS of anterior circulation non-major arteries (time from falling asleep/last use of bathroom at night to intravenous thrombolysis≤9 h and >4.5 h) admitted to Department of Neurology, Beijing Shijingshan Hospital and Department of Neurosurgery, Beijing Muyangliu Hospital from January 1 st, 2017 to December 31 st, 2021 were chosen; these 35 patients accepted routine antiplatelet therapy after intravenous thrombolytic therapy were chosen as control group, and the other 32 patients accepted rt-PA arterial thrombolysis after intravenous thrombolytic therapy were chosen as study group. Vascular recanalization after arterial thrombolysis was observed in study group (cerebral infarction thrombolysis grading 2 and 3: good vascular recanalization). Neurological deficit improvement during treatment, clinical prognoses (modified Rankin scale scores of 0-2: good prognosis) and hemorrhagic transformation incidence 3 months after treatment were compared between the 2 groups. Results:The vascular thrombolytic recanalization rate of study group was 81.25% (26/32). Patients in study group had significantly decreased National Institute of Health stroke scale scores compared with those in control group 1, 7, and 14 d after thrombolytic therapy ( P<0.05). The good prognosis rate of study group (62.50%, 20/32) was significantly higher than that in control group (37.14%, 13/35, P<0.05). No significant difference in hemorrhagic transformation rate was noted between the 2 groups (15.6% [5/32] vs. 5.71% [2/35], P>0.05). Conclusion:Patients with WUIS of anterior circulation non-major arteries (time from falling asleep/last use of bathroom at night to intravenous thrombolysis≤9 h and >4.5 h) benefit from arterial thrombolysis with rt-PA, and risk of secondary intracerebral hemorrhage is not obviously increased.

Objective::To build a reference fetal growth chart for the Chinese population based on fetal ultrasound measurements.Methods::This was a multicenter, population-based retrospective cohort study. Longitudinal ultrasound measurement data were collected from 24 hospitals in 18 provinces of China from 1 st September through 31 st October of 2019. The estimated fetal weight (EFW) was calculated based on head circumference, abdominal circumference, and femur length using Hadlock formula 3. Fetal growth curves were estimated using a two-level linear regression model with cubic splines. All participants were divided into two groups: the northern group ( n = 5829) and the southern group ( n = 3246) based on the geographical division of China and male fetus group ( n = 4775) and female fetus group ( n = 4300) based on fetal gender. The EFW was compared by fetal gender and geographical group. All statistical models were adjusted for maternal sociodemographic characteristics. Results::A total of 9075 participants with 31,700 ultrasound measurement records were included in this study. Male fetuses demonstrated significantly larger EFW compared to female ones starting at 16 weeks of gestation and extending to delivery (global test P < 0.01). The overall geographic difference in EFW was significant (global test P = 0.03), and week-specific comparisons showed that the northern group had a greater EFW starting at 15 weeks of gestation and extending to 29 weeks of gestation, although this difference did not extend to the time of delivery. The Z-score of EFW confirmed that our Chinese fetal growth charts differed from previously published standards. Conclusion::This study provides EFW and ultrasound biometric reference measurements for Chinese fetuses and reveals differences from other fetal growth charts. The chart is worth promoting in more regions of China but should be tested prudently before use.

Objective::To build a reference fetal growth chart for the Chinese population based on fetal ultrasound measurements.Methods::This was a multicenter, population-based retrospective cohort study. Longitudinal ultrasound measurement data were collected from 24 hospitals in 18 provinces of China from 1 st September through 31 st October of 2019. The estimated fetal weight (EFW) was calculated based on head circumference, abdominal circumference, and femur length using Hadlock formula 3. Fetal growth curves were estimated using a two-level linear regression model with cubic splines. All participants were divided into two groups: the northern group ( n = 5829) and the southern group ( n = 3246) based on the geographical division of China and male fetus group ( n = 4775) and female fetus group ( n = 4300) based on fetal gender. The EFW was compared by fetal gender and geographical group. All statistical models were adjusted for maternal sociodemographic characteristics. Results::A total of 9075 participants with 31,700 ultrasound measurement records were included in this study. Male fetuses demonstrated significantly larger EFW compared to female ones starting at 16 weeks of gestation and extending to delivery (global test P < 0.01). The overall geographic difference in EFW was significant (global test P = 0.03), and week-specific comparisons showed that the northern group had a greater EFW starting at 15 weeks of gestation and extending to 29 weeks of gestation, although this difference did not extend to the time of delivery. The Z-score of EFW confirmed that our Chinese fetal growth charts differed from previously published standards. Conclusion::This study provides EFW and ultrasound biometric reference measurements for Chinese fetuses and reveals differences from other fetal growth charts. The chart is worth promoting in more regions of China but should be tested prudently before use.

Objective To study the video-electroencephalography (vEEG) background activities of very premature infants within the first 7 days after birth.Method The inclusion criteria were gestational age (GA) within 31 weeks and bedside vEEG monitoring within first 7 days of birth.Those with severe cranial ultrasound (CUS) findings,refused treatment,dead and with seizures on vEEG were excluded.The clinical information of included cases were reviewed and the continuity and sleep-wake cycle (SWC) on their EEG background activities were analysed.Result From June 2017 to April 2018,a total of 56 cases were included.Their GA were (29.4 ± 1.6) weeks,and birth weight were (1 306 ± 316) g.A total of 31 cases were diagnosed with asphyxia(1 min Apgar score less than 8),and no one with 5 min Apgar score below 5.Their umbilical artery blood pHs were 7.29 ± 0.07.Their first CUS and the CUS at corrected gestational age (cGA) full term were all within the normal range.The Gesell neurological assessment at cGA 6 months were all within the normal range.As the cGA increased,the continuity of EEG background activities became more continuous as the normal continuous/discontinuous pattern.The 95％ confidence interval of max interburst interval was 95 s.The SWC first occurred at GA 26 w,but was immature,then became mature as the cGA increased.Conclusion The EEG background activity analysis of relatively normal very premature infants within first week shows that interburst interval can be longer than the previous report,and the SWC first appear at GA 26 w.

Objective To study the influence of continuous blood purification(CBP) on cardiac out-put of pediatric patients using bioreactance. Methods Patients underwent CBP in PICU and nephrology ward from March 2014 were prospectively enrolled after approval by ethics committee. CBP therapies were all performed by Fresenius Medical Care hemodialysis machine. Cardiac output values were obtained using the non-invasive cardiac output monitoring ( NICOM) device ( Cheetah Medical). Blood pressure, heart rate, cardiac index(CI) and stroke volume index(SVI) were recorded before the therapy,at the beginning of ther-apy,during the course of therapy,and at the end of each therapy. Results Twenty-one pediatric patients (from 1. 0 year to 15. 5 years) were recruited and 69 treatments were recorded from March 2014 to Decem-ber 2016. The basic CI was 3. 4 (2. 4,6. 1) L/(min·m2),basic SVI was 43 (26,75) ml/(m2·beat). Dur-ing the beginning of therapy,mean arterial pressure(MAP),CI and SVI all dropped from the baseline ( P<0. 001),whereas heart rate increased. During the course of CBP,CI and SVI (were both recorded every 4 hours) kept on dropping and stayed at a relatively lower level. Course CI was 3. 0 (2. 4,4. 6) L/(min·m2) and course SVI was 28 (21,57) ml/(m2·beat). At the end of therapy,CI was 3. 4 (2. 5,5. 3) L/(min· m2),with no significant difference from the baseline CI (P＝0. 073). However,the SVI at the end of therapy was 35 (25,67) ml/(m2·beat),higher than the course SVI but still lower than the basic SVI,the differences were statistically significant ( P<0. 05). Conclusion CI and SVI continue to decline at the beginning of CBP treatment and remain at a lower level throughout the course of treatment. After the therapy, CI has returned to the basic level whereas SVI has not recovered.

Objective To discuss the effect of low-frequency pulsed electromagnetic field (ELF-PEMFs) combined with-whole-body vibration(WBV) on the bone mineral density,bone microstructure and the biological mechanics performance inhindlimb unloading osteoporosis rats.Methods Forty female 4 months aged SD rats were randomly divided into five groups:blank group,control group,ELF-PEMFs group,WBV group,low-frequency pulsed electromagnetic field combined with wholebody-vibration(ELF-PEMFs + WBV) group.The blank group was the normal control which comprise the healthy rats.The controlgroup was the disused osteoporosis model.Except for the blank group,thehind limb unloading rats were kept for six weeks.No intervention were provided to the blank group and the control group,other three groups were treated with physical therapy.The bodyweight of rats in each group was record.Bone mineral density was measured by Dual energy X-ray absorptiometry.The right femurs was analyzed by Micro-CT and the left femur was tested through a biomechanical machine.Results After 8 weeks of continuous treatment,the ELF-PEMFs group,WBV group,ELF-PEMFs+WBV group were significantly increased in weight and bonedensity (PELF-PEMFs=0.015,PWBV=0.016,PELF-PEMFs+WBV=0.007),(tELF-PEMFs=5.956,PELF-PEMFs=0.000;tWBV=6.127,PWBV=0.000;tELF-PEMFs+WBV=4.639,PELF-PVMFs+WBV=0.000).The difference was statistically significant (F=0.091,P=0.018).The ELF-PEMFs +WBV group was significantly higher in bone formation index.The items of BV/TV,Tb.N,Tb.Th and SMI in Micro-CT analysis increased,while Tb.Sp and Conn.D index decreased significantly.Trabecular bone structure of all the three groups was improved,however the ELF PEMFs +WBV group was better than the other two groups (vs.ELF-PEMF group,PBV/TV=0.041,PTb.N=0.026,PTb.Th=0.009,PConn.D=0.030,PTb.Sp=0.045,PSMI=0.032;VS.WBV group,PBv/Tv=0.018,PTb.N=0.004,PTb.Th=0.022,PConn.D=0.042,PTb.Sp=0.039,PSMI=0.049).The maximum load,energy absorption and bone stiffness index in biomechanicalperformance test were improved.The combination treatment group were significantly improved (F=0.167,P=0.038).Conclusion Low-frequencypulsed electromagnetic field combined with whole body vibration therapy can improve bone mineral density,bone microstructureand the biological mechanics performance.They have synergistic effect and the combination therapy is better than single treatment.

Objective To evaluate the clinical value of the chemiluminescence immunoassay particles (CMIA)in the diagnosis of syphilis.Methods The serum specimens from 150 cases of syphilis in our hospital were selected as the observation group and con-temporaneous 150 serum samples from non-syphilis healthy people were selected as the control group.The toluidine red unheated serum test (TRUST),treponema pallidum particle agglutination test (TPPA)and CMIA were adopted to conduct the detection. The sensitivity,accuracy and specificity of the three kinds of method were calculated and their differences were compared and ana-lyzed.Results The sensitivity of TRUST and TPPA and CMIA was 65.3%,97.7% and 99.3% respectively,the specificity was 74.7%,97.3% and 100.0% respectively,the accuracy was 70.0%,97.0% and 99.7% respectively,the difference among three kinds of methods had statistical significance (P <0.05).The sensitivity,specificity and accuracy of TRUST were lower than those of CMIA and TPPA (P <0.017),there was no statistically significant difference between CMIA and TPPA (P >0.017).Conclu-sion CMIA is equivalent to TPPA in the sensitivity,specificity and accuracy,is superior to TRUST,and has the advantages of sim-ple operation,objective results and good repeatability.