寰枢关节后路动态固定的生物力学研究

目的探讨动态固定(转动钉、滑动钉)对寰枢关节稳定性的影响。方法用6具新鲜成人枕骨(Oc)～颈椎(C4)节段进行测试,分别模拟完整状态、损伤状态、坚强固定、转动钉固定、滑动钉固定。采用重复测量的实验设计,在完整、损伤和不同固定状态下,通过脊柱试验机对标本分别施加1.5 N·m前屈/后伸、左/右侧弯和左/右轴向旋转纯力偶矩。三维运动系统测量寰枢椎运动,分析比较固定节段角度的运动范围(range of motion,ROM)和中性区(neutral zone,NZ)。结果损伤状态下,寰枢关节ROM在前屈、后伸、侧弯和旋转方向上均显著增加,产生了寰枢关节不稳。在前屈、后伸、侧弯和旋转方向上,坚强固定和动态固定后ROM均显著减小。与坚强固定比较,动态固定仅在侧弯方向上ROM较大。动态固定显著减小了在屈伸、侧弯和旋转方向上的NZ,且与坚强固定之间的差异无显著性。结论寰枢关节动态固定后,在前屈、后伸和旋转方向上的稳定性与坚强固定相当,但在侧弯方向上较弱。动态固定能够维持寰枢关节的相对稳定。     

一种新型经椎弓根螺钉动力内固定系统的设计和力学测试

[摘要]目的设计一种新型经椎弓根螺钉动力内固定系统，并测试其对失稳腰椎的稳定性效果及对相邻节段的作用。方法 1采用6具人新鲜尸体腰椎标本，测试各个节段的活动度，为新型动力内固定系统的设计提供参数支持。2以钛合金棒、钛缆和钛合金碟片弹簧为主要结构，根据正常腰椎各节段的活动度，参照文献报道的相关测试结果，设定动态连接棒屈曲范围0~10°，旋转范围0~5°，并对其进行了相关力学测试。3制作腰椎失稳模型，测试新型动力内固定系统固定后失稳腰椎固定节段及相邻节段的运动范围（ROM）和中性区（NZ），并与坚强固定对比，同时测定其上邻节段软骨终板下压力，探讨其稳定性及对相邻节段的作用。结果 与完整脊柱相比，新型动力内固定系统固定后屈伸和侧屈方向的ROM和NZ较完整脊柱减小（P<0.05），但旋转方向的ROM和NZ与完整脊柱无显著性差异（P>0.05）。与坚强固定组相比，新型动力内固定组三个主方向的ROM和NZ均显著增加，差异有显著性意义（P<0.01）。疲劳试验后的结果表明，固定节段在三个主方向上的ROM和NZ均较疲劳前显著增加（P <0.05），但与失稳脊柱相比，差异仍具有显著性意义，与完整脊柱相比，动力内固定屈伸方向的ROM和NZ仍较小，两组相比差异显著（P <0.05），侧屈与旋转方向的ROM和NZ与完整脊柱无显著性差异（P >0.05）。结论 新型动力内固定系统可控性强、可靠性好、能够提供足够的活动度。新型动力内固定系统能对失稳腰椎提供各方向上的稳定性，尤其对前屈后伸的稳定效果最好，疲劳试验后也能提供足够的稳定性。相邻节段的ROM和上邻节段终板下压力与固定方式无显著相关。     

新型腰椎后路动态稳定系统的三维有限元分析

目的对新型腰椎后路动态稳定系统进行三维有限元分析,研究其在稳定节段及邻近节段的生物力学影响,为下腰痛的脊柱内植物的设计和应用提供参考。方法基于正常腰椎有限元模型,构建腰椎不稳损伤模型,即腰椎切除腰4和腰5之间的双侧小关节、腰4椎板下1/2、后纵韧带,形成脊柱失稳模型,分别在失稳模型上进行坚强内固定系统和后路动态稳定系统,比较两种术式对手术节段和临近阶段的活动度、各个节段的弯曲刚度、椎间盘应力水平、前纵韧带应力水平及小关节韧带拉力的变化情况。结果对内固定桥接节段(腰4/腰5)应用新型腰椎后路动态稳定系统和坚强内固定系统后,在屈伸、侧屈、轴向旋转方向上的活动度均明显减小,但坚强固定后活动度减小更明显,应用动态稳定系统活动度更接近于正常腰椎节段;腰4/腰5椎间盘最大应力均减小,但坚强固定后活动度减小更明显,应用动态稳定系统活动度更接近于正常腰椎节段;对邻近节段(腰3/腰4、腰5/S1)应用新型腰椎后路动态稳定系统和坚强内固定系统后,在屈伸、侧屈、轴向旋转方向上的活动度均有所增大,但坚强固定后活动度增加更明显,应用动态稳定系统邻近节段活动度更接近于正常腰椎节段;邻近节段椎间盘最大应力均增大,但坚强固定后增大更明显,应用动态稳定系统更接近于正常腰椎节段;应用腰椎内固定后,邻近节段的小关节应力峰值增大,并且应用腰椎坚强内固定模型的小关节应力增大更多;应用腰椎动态固定的模型邻近关节应力峰值更加接近完整腰椎模型。结论新型腰椎后路动态稳定系统对比坚强内固定系统能够使失稳节段的活动更加接近于正常,减小邻近节段的活动度增加,减小邻近节段椎间盘及小关节压力,说明新型腰椎动态稳定系统达到设计要求。     

山羊颈椎能成为人类颈椎的良好模型吗?

目的比较山羊与人颈椎的体外三维生物力学特征.方法取新鲜成年人尸体与崇明山羊颈椎标本(C0～T1)各8具,在脊柱三维运动测试仪上检测两者屈曲、后伸、左右侧屈、左右轴向旋转等模式下的运动范围和中性区.结果在前屈运动方式下,山羊和人C1-2的ROM分别为16.9°±5.1°和14.3°±3.2°,超过其它节段.在后伸运动方式下,山羊与人C1-2的ROM分别为20.6°±4.8°和18.7°±3.7° C0-1的ROM分别为19.3°±4.7°和18.4°±4.3°,超过其它节段.在轴向旋转运动模式下,山羊与人C1-2的ROM分别为48.60±8.6°和56.3°±8.9°.除山羊C4-7左右侧屈的NZ与人相比有统计学差异(P＜0.05)外,其它节段前屈、后伸、轴向旋转及左右侧屈的ROM和NZ与人相比无统计学差异(P＞0.05).结论崇明山羊与人颈椎在前屈、后伸、左右侧屈和轴向旋转等运动模式下的ROM及NZ相近,可作为颈椎研究的良好动物模型.     

腰椎单节段棘突问CoflexTM固定对脊柱三维运动的影响

目的:探讨棘突间稳定装置CoflexTM单节段固定后对固定及邻近节段活动度的影响.方法:选取6具新鲜成人尸体脊柱标本(L1～S1段),进行前屈/后伸、左右侧弯/旋转6个运动方向的稳定性测试.计算L2/3,L3/4和L4/5的=三维运动范围(ROM)和中性区(NZ),分别比较完整标本(a);CoflexTM固定L3/4(b);L3/4双侧部分失稳(c);c+b(d)4种状态下3个节段的活动度.结果:ROM值:L3/4前屈时状态b＜a,d＜c(P＜0.01),后伸时状态b、d＜a、c(P＜0.01),旋转时状态b＜a、d＜c(P＜0.05);L2/3和L4/5后伸时状态b、d＞a、C(P＜0.05),前屈及旋转时无差别(P＞0.05);侧弯时3个节段4种状态下均无差别(P＞0.05).结论:CoflexTM可以限制同定节段的前屈、后伸和旋转运动,使上下各一个邻近节段后伸活动度增加,前屈和旋转活动度无变化;对侧弯活动度均无影响.     

脊柱融合内固定致邻近节段退变的生物力学机制

目的：从生物力学角度了解融合内固定对腰椎邻近节段的影响。方法：9具新鲜腰1～骶椎尸体标本分别近、远端固定，在脊柱三维运动实验机上施以8Nm纯力偶矩模拟人体行屈伸、左右侧弯及旋转活动，观察L3～4、L4～5、L5～Sl节段运动范围(ROM)；随后进行各种模拟手术并安装内固定，依次测定CD内固定(CD)、CD加椎体间植骨(CD-骨块)、CD加TFC(CD—TFC)状态下各节段ROM值并进行统计学分析。结果：①各融合术式均可使固定节段达到即刻稳定性，L4～5节段ROM值明显减小；②L3～4节段在屈伸、侧弯和旋转时有明显位移增加，L5S1节段在旋转时ROM值明显增加，屈伸和侧弯时ROM值改变无统计学意义。结论：脊柱融合内固定术后，相邻节段位移增加、运动模式改变，易继发不稳和退变。     

脊柱三维运动分析和颈椎稳定性的实验研究

本文研制了基于双平面立体测量和计算机图像处理的脊柱三维运动的分析系统，该系统可以确定椎体的空间位置和节段间的线位移和角位移。颈椎双侧小关节切除可导致颈椎不稳定，需植骨融合或内固定。本文对Ｈａｌｉｆａｘ椎板夹和棘突钢丝固定进行了生物力学评价，作为恢复稳定性的一个指标，为临床上选择合适的固定形式提供依据。在９具新鲜成人颈椎标本（Ｃ３－Ｔ１）上、对双侧７５％小关节切除后失稳的Ｃ４－５节段，安放了Ｈａｌｉｆａｘ椎板夹和棘突钢丝固定，通过脊柱三维运动稳定性评价方法，评价它们重建颈椎稳定性的即刻效果。本文研究表明：（１）Ｈａｌｉｆａｘ椎板夹能够在前屈、后伸和侧弯运动方向上加强节段的稳定性，恢复节段的轴向旋转运动的稳定性；（２）棘突钢丝固定在前屈运动方向上可加强节段的稳定性，可恢复节段在后伸、侧弯和轴向旋转运动方向上的稳定性；（３）棘突钢丝固定后节段的前屈、后伸和侧弯运动范围均大于Ｈａｌｉｆａｘ椎板夹固定后的运动范围，尤其是在限制前屈运动时，Ｈａｌｉｆａｘ椎板夹的固定作用更为明显，但两者限制颈椎轴向旋转运动的能力相近。     

后方韧带复合体逐级切除对损伤胸腰椎稳定性的影响

目的研究后方韧带复合体逐级切除对损伤胸腰椎稳定性的影响,验证棘上韧带对维持损伤胸腰椎稳定的作用。方法取8具健康新鲜人体T11~L3节段标本,于L1椎体中1/3行楔形切除,并在材料试验机上压缩至闭合以制备L1椎体骨折。对T12~L1处后方韧带复合体按照关节囊、棘间韧带、棘上韧带、黄韧带的顺序进行逐级切除,依次连续测量T12~L1节段前屈、后伸、侧弯、旋转运动时的运动范围(range of motion,ROM)及中性区(neutral zone,NZ)变化。结果在前屈和后伸运动中,椎体切除及棘上韧带断裂后,ROM及NZ显著增加。在侧弯运动中,椎体切除和关节囊破坏后,ROM显著增加。在旋转活动中,椎体切除及关节囊破坏导致ROM增加,NZ无显著增加。结论棘上韧带断裂后,T12~L1节段稳定性发生显著下降,尤其在前屈运动中。棘上韧带是维持胸腰椎节段稳定性的关键韧带。     

胸腰段前、后纵韧带对Kaneda器械稳定性的影响

目的：用生物力学实验方式评价胸腰段脊柱椎管前方减压植骨＋Kaneda内固定术中前、后纵韧带切除对其稳定性的影响。方法：采用7具新鲜小牛胸腰段脊柱标本，模拟临床手术行L1椎体切除椎管前方减压自体髂骨植骨＋Kaneda内固定术，在WE-10A万能材料实验机上进行非破坏性生物力学测试。结果：在该术式中切除病变节段前纵韧带后胸腰椎的稳定性在旋转、轴压、前屈、后伸、侧弯各运动状态下有下降趋势，其中以后伸时最为明显，差异有统计学意义（P〈0．05）。继续切除该节段后纵韧带，胸腰椎在屈伸、侧弯和旋转运动状态下稳定性下降显著，差异有统计学意义（P〈0．05）。结论：在胸腰段脊柱椎管前方减压、植骨＋Kaneda内固定术中局部切除前纵韧带将降低内固定后脊柱在后伸状态的即刻稳定性；前、后纵韧带均切除将明显降低Kaneda器械的固定效果。     

新型人工髓核植入对腰椎稳定性影响的生物力学研究

目的: 评价一种新型果胶/聚乙烯醇复合水凝胶人工髓核的生物力学性能, 为其临床应用提供科学依据。方法: 采用6具新鲜人体标本的 L4/5脊柱功能单元进行生物力学实验, 在轴向压缩、前屈后伸和左右侧弯等运动工况下, 观察正常椎间盘、髓核摘除以及新型人工髓核CoPP植入三种状态下活动度(ROM)、中性区(NZ)的变化以及在中立位轴向加载下椎间隙高度变化。结果: 髓核摘除后, L4/5椎间屈伸、旋转、侧弯的ROM和 NZ较正常组显著增加(P<0.05), 植入CoPP人工髓核后, L4/5椎间屈伸、侧弯、旋转的 ROM和 NZ与完整椎间盘无明显差异, 除右侧弯外其他方向的ROM和 NZ较髓核摘除组明显下降　(P<0.05)。髓核摘除组在 0和500N的负荷下椎间隙高度较相同情况下正常组平均下降1.08 mm和 1.77 　mm; CoPP人工髓核植入组较相同情况下髓核摘除组分别增加1.23 mm和1.95 mm。结论: 新型果胶/聚乙烯醇复合水凝胶人工髓核植入椎间隙可维持腰椎节段正常的三维运动稳定性,恢复椎间隙高度,可望进入临床应用。     

Topical organization of the projections of neurons of the substantia nigra and the ventral field of the tegmentum of the midbrain to the head of the caudate nucleus of the cat

Neuroscience and Behavioral Physiology -     

Asymmetry of the internal connections of the striate cortex of the cat in the projection zone of the center of the field of vision

Studies were carried out on the organization of the internal connections of the striate cortex in cats in the projection zone of the center (0–5°) of the field of vision by microintophoretic application of horseradish peroxidase to electrophysiologically identified orientational columns. The area containing neurons showing retrograde labeling in most cases extended in the mediolateral direction. Labeled cells were located in the upper (II, III) and lower (V, VI) layers of the cortex, and the shapes and orientations of the areas containing labeled neurons in these layers coincided. Spatial asymmetry was detected in the distribution of labeled neurons relative to the orientational column studied. Labeled cells were located predominantly medial to the columns, regardless of the distance from the projection of the area centralis. Considering the visuotopical map of field 17, the asymmetry detected here provides evidence that neurons in orientational columns have more extensive connections with neurons of the peripheral part of the cortex. An asymmetrical distribution of “silent” zones around the receptive fields of neurons in orientational columns is suggested, and that these appear to receive influences from the periphery of the visual field. Laboratory of Visual Physiology and Laboratory of Central Nervous System Morphology, I. P. Pavlov Institute of Physiology, Russian Academy of Sciences, 6 Makarov Bank, 199034 St. Petersburg, Russia. Translated from Fiziologicheskii Zhurnal imeni I. M. Sechenova, Vol. 82, No. 12, pp. 23–29, December, 1996.     

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.     

Characteristics of the topographic interrelation of the head of the pancreas and the duodenum and pathology of the organs of the pancreatoduodenal area

Seventy pancreatoduodenal complexes of 55 patients with chronic pancreatitis and tumours of this zone and 15 patients died from other diseases are studies histotopographically . The pieces of the pancreatic head tissue in the medial wall of the duodenum were found in 12 cases of the first group and in 4 control cases. The pancreatic tissue consisted either of all elements of this organ or cystically dilated ducts and seemed to infiltrate different layers of the duodenum wall. Three variants of the pancreatic head structure are suggested on the basis of anatomo-topographical interrelationships of the pancreatic head and duodenum. In 12 out of 14 cases chronic pancreatitis and carcinoma of organs of this zone were combined with the variants of the pancreatic head structure, in 2 cases there was a true heterotopy . Pathogenetic significance of these variants for the development of chronic pancreatitis is discussed.     

Influence of the level of the transmembrane potential on the dynamics of the extinction of the amplitude of the synaptic reactions of the snail under voltage clamping conditions

The influence of the level of the transmembrane potential on the dynamics of the extinction of the amplitudes of summary excitatory postsynaptic currents arising in identified giant parietal neurons in response to rhythmic stimulation of the intestinal nerve was investigated in a preparation of the isolated CNS of the common snail in order to identify the possibility of the participation of the postsynaptic element in synaptic plasticity. It was demonstrated that, at a greater value of the transmembrane potential, the decrease in the amplitudes of the postsynaptic currents which have been induced by rhythmic stimulation takes place more rapidly. It was also demonstrated that at a higher frequency of stimulation of the nerve, the effect of the influence of the membrane potential level on the dynamics of the synaptic reactions is more prominent. The data obtained may be regarded as an argument in favor of the possibility of the participation of the post-synapse in plasticity. This study was partially supported by the Russian Basic Research Fund (project No. 94-04-12209). Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow. Translated from Zhurnal Vysshei Nervnoi Deyatel'nosti imeni I. P. Pavlova, Vol. 45, No. 1, pp. 171–179, January–February, 1995.     

Effect of the conditions of adaptation of the optic analyzer to the function of the thermoreceptors of the human skin

Summary A discussion is presented of the effect produced by light stimulation applied to the optic analyzer alone on the function of the temperature analyzer. The cutaneous-temperature analyzer was kept on constant illumination and temperature. The light effects from the retinal photoreceptors on the cutaneous thermoceptor system led to reflex changes of the functional rate of the latter. Conditions of the optic analyzer of light adaptation caused reflex adjustment of cold receptors as to heating. Dark adaptation of the eyes changed the functional state of the cold receptors, corresponding to their adjustment to low temperatures.(Presented by Active Member AMN SSSR V. V. Parin) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 57, No. 3, pp. 3–6, March, 1964