兔髌韧带压缩力学性能

目的 研究不同应变率下韧带的压缩应力-应变关系,并构建本构模型,为韧带的损伤预估及替代材料的研 发提供参考。 方法 通过万能拉伸试验机测试兔髌韧带在不同应变率(0. 001、0. 01、0. 1、1 s-1 )下的压缩力学性能 和压缩松弛响应,并构建相应的本构方程。 结果 单轴无侧限压缩实验表明,随着应变率增加,30% 、40% 应变下的 应力和切线模量均明显增大。 相比于 Gent 模型,Fung 和 Ogden 模型更适用于拟合韧带压缩曲线(R2 >0. 99);采用 4 项 Prony 级数更适用于拟合韧带的松弛曲线(R2>0. 99)。 结论 兔髌韧带的压缩力学性能有显著的黏弹性响应, Fung 和 Ogden 模型可用于拟合韧带的压缩响应,4 项 Prony 级数可用于拟合兔髌韧带的压缩松弛响应。     

不同角度制动对跟腱力学特性影响的实验研究

目的探讨不同角度制动对跟腱力学特性的影响.方法分别将兔踝关节于伸直位和背屈90°位制动4周,然后对跟腱本构方程、应力-应变关系等进行对照研究.结果正常组与二制动组之间跟腱的应力-应变关系理论曲线均有明显不同,其材料常数亦有显著差异;而在二个制动组之间却并不显著.结论"静止应力”并不能延缓制动所致的组织退变.     

改良"叉"形钢板固定股骨髁部C1型骨折的生物力学评价

目的 :评价改良“叉”形钢板对股骨髁部C1型骨折固定的生物力学性能。方法 :18具新鲜股骨下段及胫骨上段标本随机分成 3组 ,均制成股骨髁部C1型骨折模型 ,A组 :用改良“叉”形钢板固定 ;B组 :用股骨塑形钢板固定 ;C组 :用GSH钉固定。分别在MTS试验机上进行纵向压缩试验和轴向扭转试验 ,测量标本的纵向压缩位移、横向分离位移和扭转角度。结果 :改良“叉”形钢板、GSH钉、股骨塑形钢板固定组的纵向压缩位移分别为 (0 .41± 0 .0 3 )、(0 .3 8± 0 .0 1)、(0 .81± 0 .10 )mm ;横向分离位移分别为 (0 .2 0± 0 .0 1)、(0 .19± 0 .0 1)、(0 .3 0± 0 .0 1)mm ;扭转角度为 1.62°± 0 .0 7° ,1.69°± 0 .0 6° ,4.2 6°± 0 .72°。改良“叉”形钢板和GSH钉固定明显优于股骨塑形钢板 ,具有显著性差异 (P <0 .0 1)。结论 :改良“叉”形钢板用于固定股骨髁部C1型骨折 ,具有良好的生物力学性能 ,是治疗股骨髁部C1型骨折的一种较理想的内固定器械。     

脑组织压缩力学性能和本构模型

目的 研究脑组织在不同应变率下的压缩力学性能和本构模型。方法 使用电子万能试验机对猪脑组织白质和灰质开展准静态压缩和中速压缩试验,获得脑组织不同应变率下的应力-应变曲线。采用Ogden本构模型对试验曲线进行拟合,确定本构模型参数,并在有限元软件中进行仿真验证。结果 脑组织应力-应变曲线呈现非线性特征,具有较强的应变率相关性和敏感性。压缩至0.6应变时,在5×10-4~5×10-2 s-1应变率下,白质和灰质的应力分别增加102%和129%,在1~1.5 s-1应变率下则分别增加50.7%和54.6%;1.5 s-1应变率下白质、灰质应力比5×10-4 s-1应变率下分别增加347%、413%。Ogden模型拟合下的R2>0.99,仿真结果与试验结果误差在15%以内,验证了模型的有效性。结论 研究结果有助于实现对脑组织变形的预测,为建立更加科学合理的人体模拟靶标以及在设计和改进颅脑防护装备上提供准确的理论依据。     

异种骨内固定器力学性能的实验研究

目的了解牛骨材料及其构件的力学强度[抗拉、抗压、抗折(弯曲)和抗扭(剪切)强度].方法将材料分为天然、处理和构件(即产品)三组并制成标准试件,用规定设备按标准方法进行检测.结果(1)牦牛股骨拉伸、压缩、抗折、扭转极限应力分别为106.35±3.45、127.60±2.65、225.9±4.1、53.45±1.55(MPa),胫骨拉伸、压缩、抗折、扭转极限应力分别为114.96±1.46、184.75±3.25、211.35±2.45、51.9±0.5(MPa).湖区水牛胫骨拉伸、压缩、抗折、扭转极限应力分别为1 28.1±11、195.8±9.4、167.4±1 2.7、54.25±0.75(MPa).(2)E0气薰灭菌对牛骨材料的力学性能无明显影响,幅照灭菌对牛骨材料的力学性能稍有影响.(3)处理后,牛骨螺钉、圆钉的抗折强度较材料有所降低,而抗拉强度、抗压强度、抗扭强度变化不大.结论牛骨是一种力学性能良好,适合制作内固定构件的高强度生物材料.     

自体静脉移植血管的应力应变关系及其相关组织形态学研究

本文研究了自体移植静脉的应力应变关系 ,将狗股静脉移植于股动脉 ,术后 6个月切取移植静脉进行轴向及环向的单轴拉伸实验及组织形态学观测 ,并和正常股静脉、股动脉的应力 应变关系及组织形态学进行了比较。结果表明 ,轴向移植静脉及正常静脉、动脉的应力 应变关系可表示为 :T =C1 (eα1(λ-1 ) - 1) (T <10kPa)和T =C2 eα2 (λ-1 ) - β(T≥ 10kPa) ,环向应力 应变关系可表示为 :T =C3(eα3(λ-1 ) - 1)。移植术后的静脉与正常静脉、动脉相比 ,轴向和环向静脉的应力 应变曲线均向左移 ,移植术后血管管壁组织结构的刚度比正常静脉、动脉的大 ;比如 ,移植静脉和正常静脉、动脉轴向的α2 (mean±SD)的值分别为 :34 .0 6± 7.30、19.2 1± 2 .35和 11.68± 0 .2 636,环向的α3(mean±SD)的值分别为 :55.76± 2 0 .16、2 7.56± 2 .82和 2 3 .0 8± 1.2 74 1,这显示了移植血管管壁组织在术后硬化的特性。组织形态学的研究表明 ,移植术后血管的管壁材料组份及结构发生了变化 ,管壁弹性纤维含量与正常静脉相比无显著差异 ,但远低于正常动脉 ;例如 ,弹性纤维在正常动脉、静脉及移植血管中的含量分别为 (mean±SD) :4 8.9± 4 .3、19.6± 0 .6和 19.9± 2 .7,说明移植血管并未出现动脉化趋势。此外 ,移植术     

拇指腕掌关节韧带的力学特性及其意义

目的 :探讨拇指腕掌关节韧带力学特性 ,为关节运动分析、伤病致残时的修复与功能重建以及人工关节设计提供关节韧带力学特性参数。方法 :选择前斜韧带和背桡侧韧带做离体力学测试 ,得出韧带应力—应变关系、弹性模量和抗张强度 ,推导出本构方程。结果 :前斜韧带和背桡侧韧带的应力—应变关系呈幂函数关系 ,前斜韧带的本构方程 :σ =1.0 0ε1.17,背桡侧韧带的本构方程 :σ =2 .2 7ε1.60 。结论 :前斜韧带结构较疏松 ,其弹性模量和抗张强度都较背桡侧韧带小 ,外伤或自发性损伤引起退行性变的可能性大。     

医用连续碳纤维增强聚烯烃复合材料的生物力学特性测试

目的通过对医用连续碳纤维增强聚烯烃复合材料的生物力学测试,了解其作为硬组织修复材料的力学性能。方法对25根连续碳纤维增强聚烯烃复合材料棒进行拉伸、压缩、弯曲及剪切性能测试,得出该材料的最大载荷、极限强度、弹性模量、泊松比及延伸率。结果极限强度中,拉伸强度(561.11±14.24)MPa,压缩强度(341.91±1.71)MPa,弯曲强度(715.86±19.26)MPa,剪切强度(58.20±15.28)MPa。弹性模量(弯曲)(43.33±1.17)GPa;泊松比0.314±0.005;延伸率(18.20±0.55)%。结论医用连续碳纤维增强聚烯烃复合材料具有良好的生物力学特性,能满足硬组织修复的生物力学要求。     

脂肪组织压缩实验中摩擦系数对力学响应的影响

目的针对当前摩擦力对脂肪组织无约束压缩实验结果影响的不确定性,研究压缩实验中合适的摩擦系数设置及适用于模拟脂肪组织生物力学响应的材料本构模型。方法构建低应变率(0.2s^-1)和中应变率(20s^-1)下的脂肪组织有限元模型,分别应用LS-DYNA中常用于模拟脂肪组织的线性黏弹性材料本构、Mooney-Rivlin超弹性材料本构、Ogden超弹性材料本构、软组织材料本构,在不同摩擦系数下进行无约束压缩实验,分析不同摩擦系数及本构模型对接触力大小的影响。结果4种材料本构模型在低、中应变率下,输出的接触力均与摩擦系数呈正相关,有摩擦时的接触力比无摩擦时的接触力大50%左右。中应变率下脂肪组织的力学响应对摩擦系数的灵敏度比低应变率下的更高,且不同材料本构模型输出的接触力差异显著。结论在脂肪组织无约束压缩实验中,静摩擦系数取0.1,动摩擦系数取0.05是合理的,在低、中应变率下Ogden超弹性材料本构能够良好地反映脂肪组织的生物力学响应。     

自体骨—肌腿移植的解剖学研究

目的为临床治疗垂状指及屈肌腱止点重建的新方法提供解剖学依据.方法对20具40侧成人尸体的跟骨-跖肌腱、第1掌骨-拇长展肌、第2掌骨-桡侧腕长伸肌可行供区,进行止点类型、附着点面积、可切取骨块情况、以及相邻解剖结构和解剖变异等方面进行解剖学研究.并用SPSS统计软件进行统计和分析.结果.①90%的跖肌腱直接附着于跟骨而不与跟腱融合(集中型占85%),止点面积为(69.5±4.4)mm2;②93%拇长展肌腱直接附着于第1掌骨基底部桡侧(集中型占87%),止点面积为(27.9±3.4)mm2;③90%桡侧腕长伸肌腱直接附着于第2掌骨背侧或大于1/2桡背侧(集中型占90%),止点面积为(31.6±4.2)mm2.切取骨块形状分为椭圆形(平均占12%)、横形(平均占8%)、圆形(平均占7%)、弥散形(平均占13%).结论①跟骨-跖肌腱、部分第1掌骨-桡侧腕长伸肌和第2掌骨-拇长展肌的肌腱附着点形状、面积、可切取的骨块都能满足骨-肌腱移植的要求;②切取3个骨-肌腱供区对手足功能无任何影响,为临床构制骨-肌腱移植提供了解剖学依据.     

Counterpointing the functional role of the forebrain and of the brainstem in the control of the sleep-waking system

This paper reviews the lifetime contributions of the author to the field of sleep-wakefulness (S-W), reinterprets results of the early studies, and suggests new conclusions and perspectives. Long-term cats with mesencephalic transection show behavioral/polygraphic rapid eye movement sleep (REMS), including the typical oculo-pupillary behavior, even when the section is performed in kittens prior to S-W maturation. REMS can be induced as a reflex. Typical non-rapid eye movement S (NREMS) is absent and full W/arousal is present only after a precollicular section. The isolated forebrain (IF) rostral to the transection exhibits all features of W/arousal and NREMS [with electroencephalographic (EEG) spindles and delta waves], arousal to olfactory stimuli, and including the appropriate oculo-pupillary behaviors. These features also mature normally after neonatal transection. REMS is absent from the IF. After deprivation there is NREMS pressure and rebound in the IF, but the decerebrate cat only shows pressure for REMS. Most IF reactions to pharmacologic agents are within expectations, except for the tolerance/withdrawal effects of long-term morphine use which are absent. In contrast, these effects are supported by the brainstem (i.e. seen in the decerebrate cat). In cats with ablation of the telencephalon, or diencephalic cats, delta waves are absent in the thalamus. EEG thalamic spindle waves are seen triggering S for only 4-5 days after ablation. Therefore, true NREMS is absent in chronic diencephalic cats although pre- and postsomniac behaviors persist. These animals are hyperactive and show a pronounced, permanent insomnia; however, a low dose of barbiturate triggers a dramatic REMS/atypical NREMS rebound. Cats without the thalamus (athalamic cats), initially show a dissociation between behavioral hyperactivity/insomnia and the neocortical EEG, which for 15-20 days exhibits only delta and slower oscillations. Fast, low-voltage W rhythms appear later on, first during REMS, but spindle waves and S postures are absent from the start, such that these cats also display only atypical NREMS. Athalamic cats also show barbiturate-sensitive insomnia. Cats with ablation of the frontal cortices or the caudate nuclei remain permanently hyperactive. They also show a mild, but significant hyposomnia, which is permanent in afrontal cats, but lasts for about a month in acaudates. The polygraphic/behavioral features of their S-W states remain normal. We conclude and propose that: (a) the control of the S-W system is highly complex and distributed, but is organized hierarchically in a well-defined rostro-caudal manner; the rostral-most or highest level (telencephalon), is the most functionally complex/adaptative and regulates the lower levels; the diencephalic/basal forebrain, or middle level, has a pivotal role in inducing switching between S and W and in coordinating the lowest (brainstem) and highest levels; (b) W can occur independently in both the forebrain and brainstem, but true NREMS- and REMS-generating mechanisms exist exclusively in the forebrain and brainstem, respectively; (c) forebrain and brainstem S-W processes can operate independently from each other and are preprogrammed at birth; this helps understanding normal and abnormal polygraphic/behavioral dissociations in humans and normal dissociations/splitting in aquatic mammals; (d) NREMS homeostasis is present in the IF, but only REMS pressure after deprivation persists in the decerebrate cat; (e) the thalamus engages in both NREMS and W; (f) insomnia in diencephalic cats is the result of an imbalance between antagonistic W- and S-promoting cellular groups in the ventral brain (normally modulated by the telencephalon); (g) the EEG waves, which are signature for each S-W state, appear to truly drive the concomitant behaviors, e.g. a hypothetical human IF could alternate between behavioral NREMS and W/arousal/awareness; (h) a role for REMS is to keep the individual sleeping at the end of the self-limiting NREMS periods. The need for accelerating research on telencephaling NREMS periods. The need for accelerating research on telencephalic S-W processes and downstream control of the lower S-W system levels is emphasized.     

Effects of the lesion of the postcommissural part of the septum on the behavior of the rat.

The effects of the lesion of the postcommissural part of the septum on behavior of the rat has been studied. Results may be summarized as follows. An increase in the exploratory behavior in the open field which decreases rapidly; a decrease in the number of defecations in this test and a decrease in time leaving a dark environment for exploration. In the shuttle box test, no facilitation of the acquisition, but a permanent and quite significant increase in the intertrial activity has been found. We conclude that the lesions tend to decrease the emotivity of the subjects. An interpretation on the basis of the species -- specific defensive reactions explains the transitory and permanent effects of the lesions on the spontaneous activity.     

The Beauty of the Network in the Brain and the Origin of the Mind in the Control of Behavior

Behavior is not adequately described as a stimulus-response process. It is initiated by the animal and is generated because of its expected outcome in the future. The outcome can be good or bad for the animal. The brain is in charge of the selection process. This is the basic function of the brain. Taking Drosophila as a study case, this paper discusses initiating activity, several examples of outcome expectations, trying out (the internal search for a suitable behavior), chaining of actions, and the functional roles of chance in action selection. It takes mental processes and states such as goals, intentions, feelings, memories, cognition, and attention as higher levels of behavioral control that have their origin in biological evolution.     

Adequate function of the cell: Interactions between the needs of the cell and the needs of the organism

The continuous maintenance of cell adequate function (cellular stress) is considered to be the main feature which characterizes the activity of a live cell. In accordance with the concept of cellular stress, the transition of the cell to the state of adequate funcitoning represents a dual commitment. The cell must function adequately to respond to the demands of the organism and to provide for its own needs. Thus, it is proposed that two systems exist for the regulation of the adequate function of the cell: one enabling the cell to respond to the demands of the organism, and the other providing for the needs of the cell itself. The hormonal system of the organism represents the first of these mechanisms, and I believe that another system exists for regulation of intracellular needs. Adequate function of the cell is determined by the regulative, controlling and defense mechanisms. The balance between the needs of the cell and of the organism should be a concern of physician, since it provides for the optimal function and health of the organism as a whole.     

On the development of the sympathetic chain and the adrenal medulla in the mouse

Summary The first visible primordia of the sympathetic chain appear in the anterior thoracic region and run caudally through 8 segments in an embryo of 11 gestation days. At 12 gestation days the trunk reaches from the base of the skull into the sacral region. During the following days the trunk develops into ganglia with interganglionic fibers.At 16 gestation days there is a well developed trunk with a cranial ganglion cervicale superior and a ganglion stellatum in the anterior part of the thoracic region. In the remaining sympathetic chain there are segmentally arranged ganglia but in this common pattern large differences are noticed.At the 13th gestation day the first signs of the adrenal medulla and the splanchnic plexus appear in the form of sympathoblasts ventral to the sympathetic chain. The migration of sympathoblasts into the primordia of the adrenal cortex goes on for 3 days while the migration to the splancnic plexus in the mesenchym ventral and lateral to the aorta goes on at least 2 more days.     

指背腱膜滑动与近侧指间关节屈曲关系及临床意义

目的:探讨指背腱膜滑动距离与近侧指间关节(PIP)屈曲关系,为临床修复提供解剖学基础。方法:男性成人新鲜尸体标本10侧30指(示、中、环指各10指),切除手指皮肤,不破坏腱鞘、屈肌支持带、伸肌支持带、内在肌及外在肌,使肌腱保持正常的生理状态,分别测量各指中央束(CS)、侧束(LB)在PIP屈曲45°和90°时的滑动距离。结果:当PIP屈曲45°时,CS滑动距离为(2.7±0.4)mm,LB滑动距离为(2.8±0.6)mm;当PIP屈曲90°时,CS滑动距离为(4.3±0.7)mm,LB滑动距离为(4.8±0.6)mm。结论:指背腱膜滑动距离减少,严重影响手指的屈曲功能。对于指背腱膜的新鲜性损伤应予以精确修复;对于陈旧性损伤的修复应确保指背腱膜的正常滑动范围。     

Anatomical relationship between the morphology of the styloid process of the ulna and the attachment of the radioulnar ligaments

The radioulnar ligaments are the major stabilizers of the distal radioulnar joint under dynamic loading; however, anatomical detail regarding their attachment on the middle and distal thirds of the styloid process of the ulna remains unclear. Because previous anatomical studies included only old cadavers, their anatomical findings might not reflect the morphological features of younger and healthy specimens. This study investigated the anatomical features of the distal ulna, particularly the styloid process, to determine the attachment of the radioulnar ligaments to the styloid process and verified their direction and attachment to the styloid process in younger and healthy donors using magnetic resonance imaging (MRI). We investigated the morphological features of the distal ulna of 12 cadaveric wrists using micro-computed tomography (micro-CT). We also visualized and measured the distribution of the cortical bone thickness. We histologically analyzed three specimens in the axial plane and macroscopically analyzed seven specimens to examine the attachment of the radioulnar ligaments to the styloid process. In addition, we evaluated five wrists from living volunteers using 3.0 Tesla MRI. The distal ulna has a ridge on the dorsoradial aspect of the styloid process that corresponds to the attachment of the radioulnar ligaments. Micro-CT images after data processing revealed that the cortical thickness of the dorsoradial quadrant was thicker than that of the other quadrant at the proximal slice of the styloid process (p < 0.01), and that of the dorsoulnar (p = 0.021) and ulnopalmar (p < 0.01) quadrants at the middle slice. Histological analyses showed that the radioulnar ligaments were attached to the middle and distal thirds of the styloid process via chondral-apophyseal entheses. The direction of the fiber was dorsal in the middle third of the styloid process and changed to palmar in the distal third of the styloid process. The direction and attachment of the radioulnar ligaments on the styloid process were confirmed using MRI for younger and healthy participants. The radioulnar ligaments were attached to the dorsoradial ridge of the styloid process, which was confirmed by cortical bone thickening, histology at the attachment sites, and in vivo MR imaging. The directions of the radioulnar ligaments sterically intersected, which would satisfy both slipping stability and rotational mobility. These anatomical findings may provide the basis for biomechanical consideration of distal radioulnar joint stabilization.     

On the musculature of the gastro-intestinal tract of the guinea-pig

Summary The small intestine, caecum, colon and part of the stomach of guinea-pigs were studied by light microscopy, using semithin sections of plastic embedded specimens. The muscular coat is thicker in the duodenum than in the rest of the small intestine. The ratio between longitudinal and circular muscle is 1:4.6 in the duodenum and it increases regularly along the small intestine, to reach 1:2 in the terminal ileum. In the caecum, shape and sectional area of the muscle tissue were analyzed along the full length of the taeniae. In the caecal circular muscle there is a characteristic change in the arrangement of the muscle bundles from the regions in the centre of the haustrations to the regions of the grooves between haustrations or to those lying beneath a taenia. The functional significance of the taeniae is discussed in terms of an arrangement allowing reduction of the lumen of the organ (which at the level of the grooves between haustrations acquires a triangular outline) more efficiently than if the longitudinal musculature were spread over the entire surface of the organ. Haustrations are present also on one side of the wall of the ascending colon where there is no longitudinal muscle layer. In the descending colon the structure of the wall is examined in different functional states, namely in the regions between fecal pellets (constricted regions) and in the regions around a fecal pellet (moderately distended regions). The musculature increases considerably in thickness in the constricted regions (both muscle layers being actively contracted), while the mucosa and submucosa are thrown into prominent longitudinal folds. These folds produce occlusion of the lumen when the circular muscle has shortened by about 50%.     

On the origin of the corticotectal projections in the cat

Summary Stereotaxic injection of horseradish peroxidase into the superior colliculus produced retrograde labelling of layer V pyramides in the Clare Bishop area and the lateral bank of the suprasylvian sulcus, in area 17,18 and 19. Single labelled cells were also found scattered in the splenial, the suprasplenial, the lateral and the suprasylvian gyri. In the cruciate sulcus no labelled cells were observed. Autoradiographically, the lateral bank of the suprasylvian sulcus was also shown to give rise to fibres to the superior colliculus.