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 design two kinds of intensity modulated radiotherapy (IMRT) plans with different radiation field distributions,and to compare the dose differences of that at the dose of target region and organs at risk (OAR) for middle and lower esophageal cancer,so as to provide a reference for the design of IMRT plan. Methods:The data of 17 patients with middle and lower esophageal cancer who received IMRT at Shangluo Central Hospital from November 2022 to May 2023 were retrospectively analyzed. IMRT plans with different radiation fields for Plan 1 and Plan 2 were designed for each patient. The angles of radiation field for Plan 1 were 0°,80°,120°,160° and 200°,and those for Plan 2 were 30°,130°,180°,230° and 330°,respectively. The prescribed dose to the planning target volume (PTV) was 60 Gy/30 F. The differences in dosimetric parameters between the two plans were compared. Results:There were no statistically significant differences in the dose parameters of 2％,98％,50％ target dose (D2％,D98％,D50％),homogeneity index (HI),conformity index (CI) and monitor unit between the two groups (P>0.05). There were no significant differences in V5 of dual lungs,the mean dose (Dmean) of heart,and the maximum dose (Dmax) of spinal-cord between two groups (P>0.05). The volume percentage (V10,V20,V30) of dual lungs received radiation doses of 10,20 and 30 Gy,and the mean dose (Vmean) of lung in the Plan1 group reduced respectively 7.44％,21.16％,10.09％ and 5.31％ than those in the Plan2 group,and the differences of them were statistically significant (t=-5.845,-7.729,-2.247,-3.960,P<0.05). Heart V10 and V20 in the Plan1 group decreased respectively by 7.23％ and 5.78％,with statistical significance (t=-4.376,-3.523,P<0.01),while V30 and V40 of Plan 1 increased respectively by 2.7％ and 4.92％,without statistical significance (P>0.05). There was no significant difference in heart Dmean between the Plan1 group and the Plan2 group (P>0.05). Conclusion:Both two methods of distribution field can meet the clinical requirements,and Plan1 has more advantages in protecting organs at risk under the premise of meeting the requirements of target region.

Objective:To design two kinds of intensity modulated radiotherapy (IMRT) plans with different radiation field distributions,and to compare the dose differences of that at the dose of target region and organs at risk (OAR) for middle and lower esophageal cancer,so as to provide a reference for the design of IMRT plan. Methods:The data of 17 patients with middle and lower esophageal cancer who received IMRT at Shangluo Central Hospital from November 2022 to May 2023 were retrospectively analyzed. IMRT plans with different radiation fields for Plan 1 and Plan 2 were designed for each patient. The angles of radiation field for Plan 1 were 0°,80°,120°,160° and 200°,and those for Plan 2 were 30°,130°,180°,230° and 330°,respectively. The prescribed dose to the planning target volume (PTV) was 60 Gy/30 F. The differences in dosimetric parameters between the two plans were compared. Results:There were no statistically significant differences in the dose parameters of 2％,98％,50％ target dose (D2％,D98％,D50％),homogeneity index (HI),conformity index (CI) and monitor unit between the two groups (P>0.05). There were no significant differences in V5 of dual lungs,the mean dose (Dmean) of heart,and the maximum dose (Dmax) of spinal-cord between two groups (P>0.05). The volume percentage (V10,V20,V30) of dual lungs received radiation doses of 10,20 and 30 Gy,and the mean dose (Vmean) of lung in the Plan1 group reduced respectively 7.44％,21.16％,10.09％ and 5.31％ than those in the Plan2 group,and the differences of them were statistically significant (t=-5.845,-7.729,-2.247,-3.960,P<0.05). Heart V10 and V20 in the Plan1 group decreased respectively by 7.23％ and 5.78％,with statistical significance (t=-4.376,-3.523,P<0.01),while V30 and V40 of Plan 1 increased respectively by 2.7％ and 4.92％,without statistical significance (P>0.05). There was no significant difference in heart Dmean between the Plan1 group and the Plan2 group (P>0.05). Conclusion:Both two methods of distribution field can meet the clinical requirements,and Plan1 has more advantages in protecting organs at risk under the premise of meeting the requirements of target region.

Objective To study the effects of different extracorporeal circulation temperature combined with dexmedetomidine on oxidative stress in patients undergoing cardiac surgery under cardiopulmonary bypass.Methods 240 patients who underwent cardiac surgery under cardiopulmonary bypass were selected from June 2021 to June 2024.The patients were 50 to 75 years old and did not have severe hepatic or renal insufficiency.The Mini-Mental State Examination was completed 1 day before the operation.Patients were routinely established for cardiopulmonary bypass.Patients were randomly divided into four groups(n=55):hypothermia+normal saline group(L0),hypothermia+dexmedetomidine group(L1),hyperthermia+normal saline group(H0)and hyper-thermia+dexmedetomidine group(H1).The nasopharyngeal temperature was maintained at(30±1)℃in the hypothermia group and(33±1)℃in the high-temperature group during the reflux period.Dexmedetomidine injection was intravenously injected at 1 μg/kg 10 minutes before anesthesia in L1 and H1 groups,and pumped continuously at a rate of 0.5 μg/(kg·h)until the end of surgery.L0 and H0 groups were given equal volume of normal saline until the end of operation.5 mL of central venous blood was collected before the beginning of anesthesia(T1),at the end of surgery(T2),24 h(T3)and 48 h(T4)after surgery,and serum neuron specific enolase(NSE),interleukin-6(IL-6)and tumor necrosis factor-α(TNF-α)levels were detected by ELISA.The levels of superoxide dismutase(SOD)and malondialdehyde(MDA)in serum were determined by xanthine oxidase method and thiobarbituric acid method.The Confusion Assessment Method-ICU was used to evaluate the occurrence of POD.Results 220 patients were finally enrolled,including 81 patients in POD group,with an incidence of 36.8%.Compared with NPOD group,the concentrations of NSE,IL-6,TNF-ɑ and MDA in POD group were in-creased,while the concentration of SOD was decreased.Compared with L0 group,the concentrations of NSE,IL-6,TNF-ɑ and MDA were decreased and the concentration of SOD increased in L1 group.Compared with H0 group,NSE,IL-6,TNF-ɑ and MDA concentrations in H1 group were decreased,while SOD concentration was in-creased.Compared with L0 group,concentration of NSE,IL-6,TNF-ɑ and MDA increased,while the concentra-tion of SOD decreased in H0 group.Compared with L1 group,concentration of NSE,IL-6,TNF-ɑ and MDA in-creased,while the concentration of SOD decreased in H1 group.Conclusion Hypothermia combined with dexme-detomidine during cardiopulmonary bypass can reduce oxidative stress response and POD in patients.

Objective:To study the dosimetry effects of differently selected values of control point(CP)in Monaco radiotherapy planning system on dynamic intensity modulated radiation therapy(dIMRT)for esophageal cancer of middle and lower segment.Methods:Thirteen patients with esophageal cancer at middle and lower segment who received dIMRT in Shangluo Central Hospital from January to June 2023 were selected.In the Monaco radiotherapy planning system,nine groups of dIMRT plans were designed for each patient according to the 9 kinds of CP limit values(10,20,30,40,50,60,70,80 and 90).There were not changes in other optimized parameters except CP parameter.The differences of the dosimetry between target region and organs at risk(OAR)included lung,heart and spinal cord were analyzed.Results:With the increase of the CP limit value,the maximum dose of the target region which was radiation dose(D2%)of 2%volume of target region,the mean dose,which was radiation dose(D50%)of 50%volume of target region,and the homogeneity index(HI)appeared a trend of gradual stability after reduction,and the radiation dose(D98%)of 98%volume of target region which was the minimum dose of target region and the conformance index(CI)appeared a trend of gradual stability after increase.There was not significant in each dose indicator of OAR(P>0.05).The variation ranges of lung at 5,10,20,30 Gy dose(V5,V10,V20 and V30)were respectively 1.13%,0.75%,0.29%and 0.19%,and the maximum deviation of mean dose(Vmean)of lung was 18.7 cGy.The variation ranges of V10,V20,V30 and V40 in the heart were respectively 2.2%,1.23%,1.39%and 1.12%,and the maximum deviation of Vmean in the heart was 63.85 cGy,and the maximum deviation of Dmax in the spinal-cord was 70.78 cGy.There were statistically significant differences in the actual CP number(CPs),execution time(DT)of plan,and ratio value of machine unit(MU)of the complexity of plan to CPs(MU/CPs)among the plans of 9 groups(F=2.857,25.145,135.467,P<0.05),respectively.Conclusion:In the dIMRT plan of esophageal cancer of middle and lower segment,the maximum CP value is set at between 40-50,which can reduce the optimization time of the plan,the number of subfields and the treatment time of patients under the premise of meeting the dose of the target region and the OAR.

Objective:To explore the cutoff value for assessing small airway dysfunction in children with asthma.Methods:A total of 364 asthmatic children aged 5 to 14 years, with normal ventilatory function, followed up at the Asthma Clinic of the Children′s Hospital of Capital Institute of Pediatrics from January 2017 to January 2018, were selected as the case group. Concurrently, 403 healthy children of the same age range and without any symptoms in the community were chosen as the control group, and pulmonary function tests were conducted. The values of forced expiratory volume in 1 second (FEV 1), forced vital capacity (FVC), forced expiratory flow at 50% of FVC (FEF 50), forced expiratory flow at 75% of FVC (FEF 75) and maximum mid-expiratory flow (MMEF) were compared between case group and control group. Statistical tests such as t-test, χ2 test, or Mann-Whitney U test were used to analyze the differences between the groups. Receiver operating characteristic (ROC) curves were constructed, and the maximum Youden Index was utilized to determine the optimal cutoff values and thresholds for identifying small airway dysfunction in asthmatic children. Results:This study comprised 364 children in the case group (220 boys and 144 girls) and 403 children in the control group (198 boys and 205 girls). The small airway parameters (FEF 50%pred, FEF 75%pred, MMEF%pred) in the asthmatic group were significantly lower than in the control group (77% (69%, 91%) vs. 95% (83%, 109%), 67% (54%, 82%) vs. 84% (70%, 102%), 76% (66%, 90%) vs. 97% (86%, 113%), Z=12.03, 11.35, 13.66, all P<0.001). The ROC curve area under the curve for FEF 50%pred, FEF 75%pred, MMEF%pred was 0.75, 0.74, and 0.79, respectively. Using a cutoff value of 80% for FEF 50%pred achieved a sensitivity of 56.9% and specificity of 81.4%. A cutoff value of 74% for FEF 75%pred resulted in a sensitivity of 67.3% and specificity of 69.2%. Finally, using a cutoff value of 84% for MMEF%pred achieved a sensitivity of 67.9% and specificity of 77.2%. Conclusion:In the presence of normal ventilatory function, utilizing FEF 50<80% predicted or MMEF<84% predicted can accurately serve as criteria for identifying small airway dysfunction in children with controlled asthma.

OBJECTIVE To observe the changes of static functional connectivity(sFC) and dynamic functional connectivity(dFC) of amygdala subregions in patients with bilateral idiopathic tinnitus and hearing loss(TINHL). METHODS The resting-state functional magnetic resonance imaging(fMRI) data of 30 patients with bilateral tinnitus and hearing loss and 37 normal controls(NCs) were collected to analyze the intensity changes of sFC and dFC in 8 subregions of amygdala and the whole brain in TINHL patients. RESULTS There were no significant differences in age,sex and education between the two groups. Compared with the NCs group,the sFC intensity of the right basolateral subregion and right cerebellar peduncle 1 region,the left basolateral subregion and left orbital medial frontal gyrus and left angular gyrus in TINHL group was significantly decreased. The dFC intensity of left amygdalostriatal subregion and left precuneus in TINHL group was increased,but the dFC intensity was reduced in the left basolateral subregion and right angular gyrus as well as between the right superficial subregion and right medial orbital of superior frontal gyrus. CONCLUSION Among the 8 subregions of amygdala,the bilateral basolateral subregions,the left amygdalostriatal subregion and the right superficial region shown abnormal functional connectivity with other regions of the brain,which are the important parts of emotional abnormalities in TINHL.

Objective To isolate the Japanese encephalitis virus carried by Culex tritaeniorhynchus in Dongchuan District of Yunnan Province and analyze its molecular characteristics, so as to provide insights into the prevention and control of Japanese encephalitis in Yunnan Province. Methods Mosquito specimens were collected using mosquito-trapping lamps from pig farms in Batang Village and Xiaoxin Village, Dongchuan District, Kunming City, Yunnan Province in July 2016, and the mosquito species was identified according to the mosquito morphology. Then, 60 to 100 mosquitoes of each species served as a group and were ground. Baby hamster kidney-21 (BHK-21) cells and Aedes albopictus clone C6/36 cells were used for virus isolation, and positive isolates were identified using flavivirus primers. The positive isolates were amplified using reverse transcription polymerase chain reaction (RT-PCR) assay with 15 pairs of specific primers covering the full length of the genotype I Japanese encephalitis virus, and DNA sequence assembly was performed using the software SeqMan in the DNASTAR package. The obtained sequences were aligned with the complete sequences of 38 Japanese encephalitis virus downloaded from the GenBank with the software MegAlign, and the nucleotide and amino acid homology analyses of the obtained sequences were performed. The difference in amino acid sites was analyzed with the software GeneDoc, and phylogenetic trees were created based on the sequences of the coding region and E protein of the isolated Japanese encephalitis virus with the software Mega X. In addition, the secondary and tertiary structures of the E protein of the Japanese encephalitis virus were predicted using the online tool SOPMA and the software Swiss-Model. Results A total of 5 820 mosquitoes were collected and 3 843 Cx. tritaeniorhynchus (66.03%) were identified according to the mosquito morphology. A positive virus isolate, termed YNDC55-33, was isolated from Cx. tritaeniorhynchoides following batches of virus isolation from mosquito specimens, and cytopathic effect was observed following inoculation into BHK-21 and C6/36 cells. The YNDC55-33 virus isolate was successfully amplified with the flavivirus primes, and a long sequence containing 300 nucleotides was obtained. Following sequence alignment using the BLAST tool, the sequence of the YNDC55-33 virus isolate had high homology with that of the genotype I Japanese encephalitis virus. A long sequence with 10 845 nucleotides in length, which encoded 3 432 amino acids, was obtained by splicing the full sequence of the YNDC55-33 virus isolate. Phylogenetic analysis based on the whole-genome sequence and E gene sequence of the YNDC55-33 virus isolate showed that the new YNDC55-33 virus isolate was most closely related to the genotype I Guizhou isolate (GenBank accession number: HM366552), with nucleotide homology of 98.5% and amino acid homology of 99.4%, and the YNDC55-33 virus isolate shared 97.96% ± 0.33% nucleotide homology and 99.35% ± 0.08% amino acid homology with other genotype I Japanese encephalitis virus isolates, and < 90% nucleotide homology and < 98% amino acid homology with other genotypes of Japanese encephalitis virus. The YNDC55-33 virus isolate and the live attenuated virus vaccine candidate SA14-14-2 isolate differed at 16 amino acid sites on E gene, and 7 out of 8 key amino acid sites related to neurovirulence. The secondary and tertiary structures of the E protein of the YNDC55-33 virus isolate were predicted to be characterized by random coils. Conclusions A genotype I Japanese encephalitis virus was isolated from Cx. tritaeniorhynchus in Dongchuan District, Kunming City. This virus isolate and the live attenuated virus vaccine candidate SA14-14-2 isolate does not differ at antigenic epitopes-related key amino acid sites, and the major protein structure of the virus isolate is random coils. This study adds new data for the epidemiological distribution of Japanese encephalitis virus in Yunnan Province, which may provide insights into the prevention and control of Japanese encephalitis in the province.

Objective To investigate the natural penetrating radiation levels along the Qinghai-Tibet Railway, and to preliminarily evaluate the doses received by the railway employees and passengers. Methods Natural penetrating radiation was measured at 15 typical locations with different altitudes along the railway and in the carriages of a train from Lhasa to Xining using high-pressure ionization chamber RSS131, sodium iodide radiation dose rate meter MARS1561, and neutron ambient dose equivalent rate meter LB6411. Results The levels of terrestrial gamma radiation, cosmic ray ionization components, and neutron radiation were 21.5-246.6 nGy/h, 79.8-225.5 nGy/h, and 24.5-101 nSv/h, respectively. The effective dose of natural penetrating radiation received by passengers and crew on a train from Lhasa to Xining was 4.82 μSv. Conclusion Comparison with the empirical formula and verification of method reliability confirm the accuracy of the measurement. Our results provide a primary understanding of the radiation levels along the Qinghai-Tibet Railway and the radiation doses received by passengers, which can be used as a basis for the regulatory authorities.

BACKGROUND:Avascular necrosis of the femoral head is a refractory orthopedic disease that seriously affects the normal life of patients.Hip preservation is recommended for young patients due to the limited prosthesis longevity and revision.Accurate prediction of the mechanical properties of the necrotic area in the early stage and then intervention is the key to hip preservation. OBJECTIVE:To establish a dynamic contact mechanics finite element model of necrotic femoral head based on human hip CT data and predict effects of both necrotic volume magnitude and its position on biomechanics of the necrotic region under walking movement. METHODS:CT data of a volunteer were collected and then geometry model of the hip was rebuilt.Finite element model of the necrotic femoral head was established using the Abaqus software.Nine different necrotic femoral models were constructed by combined both three different necrotic volume magnitudes(small,medium and big volume)and three different necrotic positions(coincided with,medium deviated with and kept away from the line of the force).The Von Mises of the necrotic region for all models were predicted under both 3 000 N static load and dynamical loads of one whole ISO walking gait cycle.The collapse risk for all models was evaluated based on collapse criterion. RESULTS AND CONCLUSION:(1)More approaching of the necrotic region to the line of force and bigger collapse volume made the maximum Von Mises increasing.This also enlarged the collapse risk of the necrotic region.(2)For different load types,walking movement increased the maximum Von Mises of the necrotic region than that of the value under static load under the same necrotic volume and location.(3)In conclusion,dynamic load would result in increasing of the maximum Von Mises of the necrotic region comparing to static load during exercise.Therefore,the risk of local collapse will increase due to greater Von Mises.However,the overall collapse risk is lower than that of static load due to the dynamic change of bearing area.This factor should be carefully considered by surgeons when they evaluate the mechanical performance of the necrotic femoral head.