Objective To investigate stress distributions of the knee joint at 0 and 15th day after anterior cruciate ligament reconstruction(ACLR)under a compressive force through the axis of the femoral shaft onto the proximal femur.Methods A three-dimensional(3D)finite element model of the human knee joint incorporating viscoelastic material properties was developed.The one-dimensional(1D)Prony series viscoelastic constitutive model parameters for articular cartilage,menisci,ligaments,and anterior cruciate ligament(ACL)grafts were determined by fitting experimental creep curves.The viscoelastic parameters of ACL grafts at 15th day after ACLR surgery were extrapolated.Finite element simulations were then performed to analyze the von Mises stress distributions in knee ligaments,ACL grafts,articular cartilage,and menisci under 1.5 kN vertical downward compressive load applied to the femur,with loading durations of 1 second and 600 seconds.Results At 15th day after ACLR surgery,the initial relaxation modulus and equilibrium modulus of human ACL grafts remained elevated compared to native ACL tissues,resulting in a significantly higher stress concentration within the grafts relative to healthy ACL.Despite the compromised mechanical properties of the grafts after ACLR surgery,the vertical downward compressive force applied to the femur under both short-term(1s)and prolonged(600 s)loading durations,exhibited a minimal biomechanical impact on articular cartilage and meniscal structures.Conclusions Following ACLR,vertical compressive loads during weight-bearing rehabilitation exercises such as standing demonstrate minimal impact on articular cartilage and meniscus,while promoting fibrous regeneration of the graft.This renders such exercises a prudent early-stage rehabilitation strategy.Graft preparation requires balanced consideration of elastic and viscous properties,with grafts exhibiting higher relaxation modulus and viscosity coefficient than healthy ACL proving more effective in maintaining early postoperative knee stability.

Objective To investigate stress distributions of the knee joint at 0 and 15th day after anterior cruciate ligament reconstruction(ACLR)under a compressive force through the axis of the femoral shaft onto the proximal femur.Methods A three-dimensional(3D)finite element model of the human knee joint incorporating viscoelastic material properties was developed.The one-dimensional(1D)Prony series viscoelastic constitutive model parameters for articular cartilage,menisci,ligaments,and anterior cruciate ligament(ACL)grafts were determined by fitting experimental creep curves.The viscoelastic parameters of ACL grafts at 15th day after ACLR surgery were extrapolated.Finite element simulations were then performed to analyze the von Mises stress distributions in knee ligaments,ACL grafts,articular cartilage,and menisci under 1.5 kN vertical downward compressive load applied to the femur,with loading durations of 1 second and 600 seconds.Results At 15th day after ACLR surgery,the initial relaxation modulus and equilibrium modulus of human ACL grafts remained elevated compared to native ACL tissues,resulting in a significantly higher stress concentration within the grafts relative to healthy ACL.Despite the compromised mechanical properties of the grafts after ACLR surgery,the vertical downward compressive force applied to the femur under both short-term(1s)and prolonged(600 s)loading durations,exhibited a minimal biomechanical impact on articular cartilage and meniscal structures.Conclusions Following ACLR,vertical compressive loads during weight-bearing rehabilitation exercises such as standing demonstrate minimal impact on articular cartilage and meniscus,while promoting fibrous regeneration of the graft.This renders such exercises a prudent early-stage rehabilitation strategy.Graft preparation requires balanced consideration of elastic and viscous properties,with grafts exhibiting higher relaxation modulus and viscosity coefficient than healthy ACL proving more effective in maintaining early postoperative knee stability.

Objective:To present a set of clinically representative quality assurance (QA) test cases for stereotactic radiosurgery (SRT) plans of multiple intracranial metastases, in order to assess the plan quality and machine execution capabilities.Methods:Based on the clinical characteristics of multiple brain metastases, four groups of test cases with three target volumes (TVs), six TVs, nine TVs, and TVs near organs at risk (OARs) were designed. For these cases, SRT plans were developed, and plan quality was assessed using metrics including the Radiation Therapy Oncology Group conformality index (RTOG CI), gradient index (GI), homogeneity index (HI), and the volume of normal brain tissue receiving a dose of 24 Gy ( V24 Gy), which was defined as the volume enclosed by the 24 Gy isodose line around the Brain-PTV ( V24 Gy of Brain-PTV). Verification plans were generated for each test case, including the verification of point doses, planar doses (PD), and SRS MapCHECK (SMC) semiconductor matrix planar doses. Compared with the calculated result of the treatment planning system (TPS), the criteria for the γ analysis of planar doses were set at 1 mm/2% and 2 mm/2%. Results:For the four groups of test cases, the mean CI, GI, HI, and V24 Gy of Brain-PTV were 1.04±0.03, 3.79±0.40, 0.73±0.01 and (7.46±3.80) cm 3, respectively. The mean deviations of the point doses were 0.88%±0.98%, 1.47%±0.79%, 1.52%± 0.76%, and 1.17% ± 0.38%, respectively. The mean γ passing rates of the single fields for PDs were greater than 98% at 2 mm/2% and exceeding 96% at 1 mm/2%, and the mean γ pass rates of the SMC semiconductor matrix for PDs were 97.75% ± 2.31% and 99.33% ± 0.62%, at 1 mm/2% and 2 mm/2% respectively. Conclusions:The proposed QA test cases for SRT of multiple intracranial metastases allow for the effective assessments of the plan quality and machine execution capabilities and, thus, can assist various centers in clinical applications.

High altitude heart disease(HAHD)is a chronic mountain sickness in which the body is exposed to high altitude(＞2 500 m)hypobaric hypoxia environment for a long time.HAHD has high morbidity and poor prognosis,and pulmonary hypertension is the main causative mechanism for its develop-ment.The phosphodiesterase-5 inhibitor sildenafil has become a hot drug for the treatment of pulmonary hypertension.This paper reviews the progress of HAHD and discusses the mechanism of action and effectiveness of sildenafil in the treatment of HAHD,with a view to providing a basis for the treatment of HAHD with sildenafil.

High altitude heart disease(HAHD)is a chronic mountain sickness in which the body is exposed to high altitude(＞2 500 m)hypobaric hypoxia environment for a long time.HAHD has high morbidity and poor prognosis,and pulmonary hypertension is the main causative mechanism for its develop-ment.The phosphodiesterase-5 inhibitor sildenafil has become a hot drug for the treatment of pulmonary hypertension.This paper reviews the progress of HAHD and discusses the mechanism of action and effectiveness of sildenafil in the treatment of HAHD,with a view to providing a basis for the treatment of HAHD with sildenafil.

Objective:To present a set of clinically representative quality assurance (QA) test cases for stereotactic radiosurgery (SRT) plans of multiple intracranial metastases, in order to assess the plan quality and machine execution capabilities.Methods:Based on the clinical characteristics of multiple brain metastases, four groups of test cases with three target volumes (TVs), six TVs, nine TVs, and TVs near organs at risk (OARs) were designed. For these cases, SRT plans were developed, and plan quality was assessed using metrics including the Radiation Therapy Oncology Group conformality index (RTOG CI), gradient index (GI), homogeneity index (HI), and the volume of normal brain tissue receiving a dose of 24 Gy ( V24 Gy), which was defined as the volume enclosed by the 24 Gy isodose line around the Brain-PTV ( V24 Gy of Brain-PTV). Verification plans were generated for each test case, including the verification of point doses, planar doses (PD), and SRS MapCHECK (SMC) semiconductor matrix planar doses. Compared with the calculated result of the treatment planning system (TPS), the criteria for the γ analysis of planar doses were set at 1 mm/2% and 2 mm/2%. Results:For the four groups of test cases, the mean CI, GI, HI, and V24 Gy of Brain-PTV were 1.04±0.03, 3.79±0.40, 0.73±0.01 and (7.46±3.80) cm 3, respectively. The mean deviations of the point doses were 0.88%±0.98%, 1.47%±0.79%, 1.52%± 0.76%, and 1.17% ± 0.38%, respectively. The mean γ passing rates of the single fields for PDs were greater than 98% at 2 mm/2% and exceeding 96% at 1 mm/2%, and the mean γ pass rates of the SMC semiconductor matrix for PDs were 97.75% ± 2.31% and 99.33% ± 0.62%, at 1 mm/2% and 2 mm/2% respectively. Conclusions:The proposed QA test cases for SRT of multiple intracranial metastases allow for the effective assessments of the plan quality and machine execution capabilities and, thus, can assist various centers in clinical applications.

Objective To understand the respiratory protection competency of staff in hospitals.Methods Staff from six hospitals of different levels and characteristics in Beijing were selected,including doctors,nurses,medical technicians,and servicers,to conduct knowledge assessment on respiratory protection competency.According to exposure risks of respiratory infectious diseases,based on actual cases and daily work scenarios,content of respira-tory protection competency assessment was designed from three aspects:identification of respiratory infectious di-seases,transmission routes and corresponding protection requirements,as well as correct selection and use of masks.The assessment included 6,6,and 8 knowledge points respectively,with 20 knowledge points in total,all of which were choice questions.For multiple-choice questions,full marks,partial marks,and no mark were given respective-ly if all options were correct,partial options were correct and without incorrect options,and partial options were correct but with incorrect options.Difficulty and discrimination analyses on question of each knowledge point was conducted based on classical test theory.Results The respiratory protection competency knowledge assessment for 326 staff members at different risk levels in 6 hospitals showed that concerning the 20 knowledge points,more than 60％participants got full marks for 6 points,while the proportion of full marks for other questions was relatively low.Less than 10％participants got full marks for the following 5 knowledge points:types of airborne diseases,types of droplet-borne diseases,conventional measures for the prevention and control of healthcare-associated infec-tion with respiratory infectious diseases,indications for wearing respirators,and indications for wearing medical protective masks.Among the 20 knowledge questions,5,1,and 14 questions were relatively easy,medium,and difficult,respectively;6,1,4,and 9 questions were with discrimination levels of ≥0.4,0.30-0.39,0.20-0.29,and ≤0.19,respectively.Conclusion There is still much room for hospital staff to improve their respiratory protection competency,especially in the recognition of diseases with different transmission routes and the indications for wearing different types of masks.

ObjectiveBody fluid stains left at crime scenes are frequently trace amounts, while the identification of body fluids through real time fluorogenic quantitative technique often necessitates the repeated detection within the limited sample, as multiple miRNA markers are the basis for the identification. Based on the goal of both the throughput and efficiency improvement of miRNA analysis in trace samples, a duplex real time fluorogenic quantitative PCR assay system was designed to accurately quantify two miRNAs simultaneously, and the system should be further verified by actual sample for the body fluid identification. MethodsThe duplex real time fluorogenic quantitative PCR system of miR-451a to miR-21-5p was established with specially designed primers and probes, and the concentrations of the primers and probes were both optimized. The specificity, sensitivity and reproducibility of the system were validated, while its capability for body fluid identification was assessed using the miR-451a to miR-21-5p ratio. ResultsThe optimized assay system exhibited excellent specificity and repeatability, with coefficients of variation consistently below 8% for both intra- and inter-batch variability. The amplification efficiency of miR-451a and miR-21-5p reached 71.77% and 74.81%, respectively, with high and relatively consistent results. By utilizing this duplex real time fluorogenic quantitative PCR assay system, a total of 58 body fluid samples were analyzed, exhibiting a discrimination rate of 100% between blood and non-blood samples, as well as between peripheral blood and menstrual blood samples. Moreover, the results, obtained from single real time fluorogenic quantitative PCR assay system and duplex real time fluorogenic quantitative PCR assay system, showed no statistically significant difference with randomly selected blood samples (n=20). Compared to previous single real time fluorogenic quantitative PCR assay system, the sensitivity of duplex real time fluorogenic quantitative PCR assay system exhibited remarkable improvement. A minimum input of only 0.1 ng total RNA was sufficient for accurate detection of peripheral blood and menstrual blood samples, while saliva, semen, and vaginal secretion required only 1 ng total RNA for precise identification purposes. Additionally, the duplex real time fluorogenic quantitative PCR assay system successfully differentiated between different types of body fluids in simulated samples under natural outdoor conditions. ConclusionThe duplex real time fluorogenic quantitative PCR assay system effectively reduced both the time and material costs by half compared to the single system, especially suitable for the examination of body fluid stains left at crime scenes, solving the contradiction between the trace amount and the multiple sample volumes demand of repeated real time fluorogenic quantitative PCR. The duplex real time fluorogenic quantitative PCR assay successfully distinguished blood and other body fluid, as well as peripheral blood and menstrual blood samples, which maintains an equivalent capability for body fluid identification with half sample, time and reagent consumption. This system provides an efficient tool for identifying suspicious body fluids, as well as a foundation for more multiplexed real time fluorogenic quantitative PCR assay system research.

Purpose: This study compared the efficacy of heat insulation between 5% dextrose and 0.9% saline in radiofrequency ablation (RFA). Accordingly, temperature variations and maximum temperatures were assessed at identical distances and heat field distributions. Methods: Cubes of porcine liver tissue, measuring 10 mm across, were selected to precisely align the ablation boundary with the tissue boundary. An 18-gauge electrode with a 7-mm tip was inserted into each cube (10 per group) in a stainless-steel cup containing 40 mL of 5% dextrose or 0.9% saline. Fixed ablation was performed for 3 minutes using continuous mode at 30 W, simulating the typical thermal environment during thyroid RFA. Real-time temperature measurements were recorded by sensors positioned 0, 1, 3, and 5 mm from the cube’s edge. A comparative analysis was conducted to assess the maximum temperature, temperature variation, and duration of temperatures exceeding 42℃. Results: In both groups, the temperature curve declined with increasing distance from the edge of the ablated tissue. However, 0.9% saline exhibited higher maximum temperatures at 1, 3, and 5 mm compared to 5% dextrose (1 mm: 44.55°C±5.25°C vs. 34.68°C±3.07°C; 3 mm: 39.64°C±2.53°C vs. 29.22°C±2.21°C; 5 mm: 38.86°C±2.14°C vs. 28.74°C±2.51°C; all P<0.001). Considering a nerve injury threshold of 42°C, the 0.9% saline also displayed a greater proportion of samples reaching this temperature and a longer duration of temperatures exceeding it (P<0.05). Conclusion The heat insulation efficacy of 5% dextrose at 1-5 mm exceeds that of 0.9% saline at identical distances and in a common thermal environment during thyroid RFA.

Phosphatase and tensin-homolog deleted on chromosome 10 (PTEN) is an important cancer suppressor gene. Its pathogenic mutation leads to PTEN hamartoma tumor syndrome (PHTS), a rare syndrome also known as Cowden syndrome, which is relevant to early-onset hereditary breast cancer (BC). In this paper, we report three patients with unilateral multicentric BC and synchronous and metachronous bilateral BC who harbored PTEN gene mutations, and summarize the clinical manifestations, pathological characteristics, diagnosis, treatment and follow-up outcomes to provide reference for management of PTEN gene mutation-related BC among the Cowden syndrome population.