模拟失重对人体骨骼肌体积和肌内乙酰胆碱/肌酸比值的影响及等张运动对肌萎缩的作用

目的：研究模拟失重对人体骨骼肌体积和肌内乙酰胆碱／肌酸（Cho/Cr)比值的影响，并观察卧床期等张肌肉锻炼的抗肌萎缩作用。方法：10名健康青年男性志愿者，进行卧床3周的模拟失重试验，将其随机分为卧床对照组（5人）和卧床运动训练组（5人）。使用核磁共振成像和磁共振波谱观察卧床前后右侧大腿骨骼肌体积，肌四头肌体积和比目鱼肌内Cho/Cr的变化，使用REV9000等速测力系统测试其膝关节伸肌相对峰力矩的变化。结果：两组受试者卧床后右侧大腿骨骼肌体积、肌四头肌体积和膝关节伸肌相对峰力矩除Cho/Cr外均较卧床前显著下降，以股四头肌体积变化最显著。对照组与训练组间差异无显著性意义。结论：模拟失重对人体下肢骨骼肌短期内即可出现以伸肌为主的萎缩和膝关节伸肌相对峰力矩的下降。本组数据未能显示出等张运动对抗肌萎缩有显著的作用。     

计算机模拟与检测离体猪肝植入式微波辐射热场

目的 :探讨计算机模拟超声引导下植入式微波辐射热场在离体猪肝中的可行性。材料和方法 :对临床常用的能量输出条件下微波热凝固的范围和温度分布进行了计算机模拟和检测。通过实验得到了离体猪肝的模拟参数 ,建立了离体猪肝的计算机模拟热场图 ;在 2 6个猪肝上进行了 496个点次的测温以验证模拟热场的准确性。结果 :微波辐射时离体猪肝温升曲线与计算机模拟温度曲线有很好的一致性的占 88.91% ,猪肝凝固边界温度与计算机模拟的 5 4℃所对应的边界有较好的吻合性。结论 :用计算机模拟离体猪肝微波热场是准确的 ,该方法的确立为计算机模拟活体组织的研究奠定了基础     

Motor imagery training enhances motor skill in children with DCD: A replication study

BackgroundChildren with impaired motor coordination (or DCD) have difficulty using motor imagery. We have suggested that this difficulty is explained by the internal modeling deficit (IMD) hypothesis of DCD. Our previous training study lent support for this hypothesis by showing that a computerized imagery training protocol (involving action observation, and mental- and overt-rehearsal) was equally effective to perceptual-motor therapy (PMT) in promoting motor skill acquisition.AimsThe study presented here was designed to replicate and extend this finding, targeting a select group of children with moderate-to-severe DCD.Methods and ProceduresAll 36 children with DCD who participated were referred to the study and scored below the 10th percentile for their age on the Movement Assessment Battery for Children (MABC). Using a randomized control trial, the referred children were assigned randomly to one of three groups using a blocked procedure: imagery training, perceptual-motor training (PMT), and wait-list control. Motor proficiency was measured using the MABC, pre and post-training. Individual training consisted of 60-min sessions, conducted once a week for 5 weeks.ResultsResults showed that the imagery protocol was equally effective as PMT in promoting motor skill acquisition, with moderate-to-large effect sizes. Individual differences showed that the majority of children in the two intervention groups improved their motor performance significantly.ConclusionsOverall, these results further support the use of motor imagery protocols in the treatment of DCD, and tentative support for the IMD hypothesis. Developmental and dose issues in the implementation of imagery-based intervention are discussed.     

Patho-mechanical comparative morpho-characterization of contre-coup injuries of liver by cadaveric experimental simulation for medico-legal and forensic implications

BackgroundLiver is the most common organ to get injured in cases of blunt force trauma to the abdomen (BFTA). It is the 2nd commonest organ after brain to sustain injuries out of all the trauma related fatalities. However, the literature about contre-coup injuries to the liver due to BFTA is scarce in-spite of the high mortality rates seen out of injury to this particular organ.PurposeThe authors intended to systematize the characteristic morphogenesis of the contre-coup injuries of the liver on the basis of the patho-mechanics involved in various types of BFTA.MethodologyOne hundred and sixty three cases of BFTA were identified, and interpretation was attempted for the contre-coup rupture of the liver seen in twenty out of all the trauma related fatalities that presented for post-mortem examination during the study period. However, the mechanics of the pattern of the rupture injuries to the liver were indiscernible. This motivated the authors to conduct the comparative characterization of injuries to the liver by experimental simulation of BFTA after necessary permission via inflicting pre-calculated forces on unclaimed cadavers.ResultsThe patterns of contre-coup rupture/s of liver were established in all the twenty out of one sixty-three cases of BFTA. The rupture depicted patterns of injury in the situations of - 1) strong hits with a limited surface trauma, 2) very strong hits with a generalized surface trauma, 3) and collision with a solid surface resulting due to fall onto the side of the abdomen. The causative mechanism discerned was deformation of the liver, followed by its parenchymal rupture due to the shear and strain types of force/s consequent upon tissue compression. The minimum force and energy of impact required for the liver to rupture was estimated to be 2000 N and 141.5 J.ConclusionThis series of the simulation experiments revealed two variants of liver rupture in the contre-coup impact zone. The pattern of injury was maintained in cases, those studied at post-mortem examinations, but the relief ruptures were found to vary depending upon the overall mechanics of the traumatic forces involved in the simulation experiments performed on the cadavers. The anti-shock ruptures were formed during shock trauma, and shockproof ruptures were not seen in cases of underlying compressive forces. The morphogenetic characterization of the relief rupture surface of the liver was also delineated in relation to its surface orientation to the spine on the basis of the terms “large” and “very large” depicting the quantum of force/s delivered out of an impact or blow.     

Reconstruction of a real-world car-to-pedestrian collision using geomatics techniques and numerical simulations

The aim of this study is to provide an improved method for traffic accident reconstruction based on geomatics techniques and numerical simulations. A combination of various techniques was used. First, an unmanned aerial vehicle (UAV), laser scanner and structured-light scanner were used to obtain information on the accident scene, vehicle and victim. The collected traces provided detailed initial impact conditions for subsequent numerical simulations. Then, multi-body system (MBS) simulations were conducted to reconstruct the kinematics of the car-to-pedestrian collision. Finally, a finite element (FE) simulation using the THUMS model was performed to predict injuries. A real-life vehicle-pedestrian collision was used to verify the feasibility and effectiveness of this method. The reconstruction result revealed that the kinematic and injury predictions of the numerical simulations effectively conformed to the surveillance video and investigation of the actual accident. UAV photogrammetry was demonstrated to be more efficient in accident data collection than hand sketch and measurement, and 3D laser scanning enabled an easier and more accurate modeling process of vehicle. The present study shows the feasibility of this method for use in traffic accident reconstruction.     

数字技术在人工全髋关节置换术中的应用研究

目的探索把数字技术应用于人工全髋关节置换术,为临床选择更适配的人工全髋关节假体提供新的方法。方法6例成人病变的髋关节和42-56号的髋臼假体和01-04号钛合金股骨柄(矩形,HA微孔)假体连续CT扫描,将CT扫描数据经Mimics软件处理,3D计算建立髋关节和假体的数字模型。将数据输入SPSS 17.0进行统计学分析。根据术前选择的假体施行手术,术后6个月根据Harris评分进行评价,并与同期6例行传统人工全髋关节置换术患者髋关节Harris评分进行统计学比较。结果 6例骨盆三维模型数据测量结果分析:髋臼前倾角、外展角与身高、性别、侧别因素无显著性差异;股骨颈前倾角及颈干角与侧别、性别及身高因素无统计学差异。结论数字技术可以指导选择更匹配的全髋关节假体,提高人工全髋关节置换术的近期效果,为临床术前选择全髋关节假体提供一种新的方法。     

Preparing teams for low-frequency emergencies in Norwegian hospitals

BACKGROUND: Medical emergencies and major trauma require optimal team function. Leadership, co-operation and communication are the most essential issues. Due to low caseloads such emergencies occur rarely in most Norwegian hospitals. Team training of personnel between real emergencies is expected to improve performance in comparable settings. Most hospitals have cardiac arrest teams, but it is known that the training of such multiprofessional teams varies widely. We wanted to know if this also was the case for trauma teams and resuscitation teams for newborns. METHODS: A telephone survey of training practices in all the Norwegian hospitals with acute cover was conducted in 2002. Information was obtained on whether trauma teams and neonatal resuscitation teams had participated in practical multiprofessional training during the previous 6 or 12 months. RESULTS: Information was obtained from all 50 hospitals. Of the acute care hospitals, 30% had trained their trauma teams during the previous 6 months, and an additional 18% when considering the previous year, while 38% of neonatal wards had multiprofessional training during the previous 6 months, and additionally 13% had had training during the previous year. Additionally four neonatal wards had had regular training of nurses only. More than 80% of all respondents judged regular team training to be achievable, and none considered this training impossible. CONCLUSION: Only half the Norwegian acute care hospitals reported at least yearly training of trauma and neonatal resuscitation teams. Regular team training represents an underused potential to improve handling of low-frequency emergencies.     

模拟失重对离体大鼠肺动脉血管调节功能的影响

目的 研究模拟失重对离体大鼠肺血管调节功能的影响,旨在探讨模拟失重对肺循环的影响和立位耐力降低的发生机制. 方法采用尾部悬吊(TS)大鼠模拟失重生理效应.24只健康雄性Wistar大鼠随机分为对照组、TS 7 d和TS 14 d共3组.采用离体肺灌流技术,利用Power-lab生理系统记录恒流下大鼠肺循环灌注压的变化,并分别于苯肾上腺素(PE)、乙酰胆碱(Ach)和硝普钠(SNP)药物干预后,观察离体肺血管反应性,并计算出肺血管阻力. 结果与对照组相比,TS7 d和TS 14 d大鼠离体肺在恒流灌注下肺动脉压明显降低(F=3.58～20.86,P<0.05或P<0.01),离体大鼠肺动脉血管对PE的收缩反应明显下降,对Ach和SNP的舒张反应明显增强,同时肺血管阻力也相应降低(F=3.56～20.44,P<0.05或P<0.01). 结论尾吊大鼠离体肺血管灌注压降低,血管收缩反应性降低、舒张反应性增强,肺血管阻力减弱,尾吊模拟失重大鼠肺循环血管调节功能减弱,对失重后立位耐力不良有一定的影响.     

July 2003

The effect of the Prandtl number (Pr) and the Reynolds number (Re) on the behaviour of weak laminar axisymmetric and plane fountains has been studied using dimensional and scaling analyses and direct numerical simulation. For Fr 1.0 and assuming viscous effects are important, the analysis shows that for both the axisymmetric and plane fountains, y_mFrRe^–1/2, where Fr is the Froude number defined at the fountain source and y_m is the non-dimensionalized fountain height. These scalings are also valid for the non-dimensionalized fountain width. The analyses also shows _msFr², where _ms is the non-dimensionalized time scale for the fountain flow in the fountain core to reach steady state, and using this time scale y_TFr(RePr)^–1/2, where y_T is the non-dimensionalized thickness of the temperature layer on the symmetry axis over which the fountain fluid temperature changes from the inlet value to that of the ambient fluid. All these scalings have been quantified by the direct numerical simulations, hence confirming in certain ranges the phenomenological scaling obtained in this paper. The financial supports from the National Natural Science Foundation (grant numbers 19872059 and 10262003) and Yunnan Province of the People's Republic of China to W. Lin and the Australian Research Council are gratefully acknowledged.