裸鼹鼠心脏显微结构与超微结构观察

目的 观察和分析裸鼹鼠心脏的形态结构与组成,以了解裸鼹鼠心脏是否在耐受低氧、长寿以及对抗心血管类疾病等方面有独特功能.方法 采集裸鼹鼠心脏经石蜡切片后进行苏木精-伊红染色,然后光学显微镜下观察裸鼹鼠心脏的显微结构,以及经冰冻超薄切片和染色后,通过透射电镜观察和分析裸鼹鼠心脏的超微结构.结果 光学显微镜观察发现,裸鼹鼠心脏体积较小鼠大,心壁也明显较厚,心肌细胞体积也略大,血管分布更为丰富广泛;透射电镜观察显示,裸鼹鼠心肌中线粒体较小鼠丰富,而体积较小,线粒体结构正常,但肌小节略有类似缺血的病变.结论 裸鼹鼠长期低氧的洞道生活史使其心脏形态结构发生了许多适应性变化,从而使其在对抗衰老和肿瘤方面有着独特的积极影响.     

Novel colloidal associations of soyasaponins and lipid components (DPPC,cholesterol) as potential adjuvants for vaccines

Soyasaponins from soybean (Glycine max) represent promising new potent adjuvants for vaccine research because of their immunostimulating properties and weak hemolytic activity. In the present study, saponin microstructures of soyasaponins (soyasaponin Bb, soyasaponin Ab) with lipid components (cholesterol, DPPC (dipalmitoylphosphatidylcholine)) were designed by the lipid film method. In interaction studies between soyasaponins (soyasaponin Ab/Bb) and Langmuir monolayers (model membranes), composed of cholesterol and DPPC, marked interactions between soyasaponins and a pure cholesterol monolayer were observed. No interaction was detected for soyasaponins with a pure DPPC monolayer. The intercalation of soyasaponins in a mixed DPPC/cholesterol (3:1, w/w) monolayer was only observed for the monodesmosidic soyasaponin Bb whereas the second sugar chain of the bidesmosidic soyasaponin Ab impaired the access to the monolayer. Transmission electron microscopy was used for visualizing particle formation of soyasaponins and lipid components. Pseudo-binary systems (soyasaponin Ab/Bb, cholesterol) formed colloidal associations built up from ring-like subunits in the nanometer size range. In pseudo-ternary systems (soyasaponin, cholesterol, DPPC) soyasaponin Bb attacked the liposomal membrane by forming colloidal associations. Colloidal associations in pseudo-ternary systems with soyasaponin Ab, cholesterol and a phospholipid were only observed in the presence of PE (phosphatidylethanolamine) instead of DPPC. In an MTT assay with a HaCaT cell line (keratinocyte cell line) the cell viability was neither affected by the soyasaponins nor by the corresponding formulations. Both the pure soyasaponin solution and the saponin formulations may be promising adjuvant systems for the intradermal vaccine application. Furthermore, interaction studies between the model antigen ovalbumin and colloidal associations of saponins and cholesterol using MST (Microscale Thermophoresis) gave first indications of an antigen binding to colloidal associations. Ex vivo T-cell proliferation in the presence of soyasaponin Ab was confirmed.     

坏死股骨头结构特征的微纳观分析

研究股骨头坏死后,不同部位骨小梁的微细结构特征的变化.将内出血严重部位作为出血区,无内出血现象的中心部位作为参照区,分别制备未脱钙参照区、未脱钙出血区、脱钙出血区、脱钙参照区4种样本,在扫描电镜和透射电镜下观测、比较骨小梁的微纳观结构.结果发现,出血区微细结构清晰有序,而参照区则看不到有序的微细结构.股骨头坏死后不同部位不仅显示出不同的宏观特征,其内部微细结构也发生了不同的变化.     

Tensile testing of bone over a wide range of strain rates: effects of strain rate,microstructure and density

Uniaxial tensile tests were performed on standardised longitudinal specimens of bovine compact bone at strain rates from 5·3×10^?4 to 237 s^?1. After testing, the microstructure and dry density of each specimen was determined. The test results demonstrated highly significant (P<0·01) positive correlations between ultimate strength and strain rate, and between ultimate strength and density. A highly significant negative correlation between ultimate strength and the extent of secondary Haversian remodelling was also found. The modulus of elasticity showed similar correlations with the test parameters. A multiple linear-regression analysis was used to derive equations for the ultimate strength and modulus as functions of strain rate and microstructure. The regression analyses accounted for 86% of the variance in strength and 50% of the variance in modulus. The extent of secondary Haversian remodelling showed a significant (P<0·01) negative correlation with the energy-absorption capacity. Strain rate also had a significant effect on the energy-absorption capacity. Specimens tested at higher strain rates generally absorbed more energy during failure. There was no evidence of a critical velocity at which the energy absorption capacity attained a maximum. The test results correlate well with previous studies of the mechanical properties of compact bone.     

宽带激光熔覆工艺参数对梯度生物陶瓷复合涂层组织与烧结性的影响

采用宽带激光熔覆技术,在T i-6A l-4V合金上制备了梯度生物陶瓷复合涂层,并研究了宽带激光熔覆工艺参数对梯度生物陶瓷涂层显微组织与烧结性的影响。结果表明:当光斑尺寸D、扫描速度V不变时,随着输出功率P的增加,生物陶瓷涂层的致密度逐渐下降;随着输出功率P的增加,生物陶瓷层中的孔隙率逐渐增大。当P=2.3 KW时,生物陶瓷层中组织致密,孔隙率低(5.11%),当P=2.9 KW时,生物陶瓷涂层组织致密度差,孔隙率高达21.32%。生物陶瓷涂层显微硬度分析表明,P=2.3 KW时,显微硬度最高值约为1 100 HV。本实验条件下,宽带激光熔覆梯度生物陶瓷复合涂层的最佳工艺参数为P=2.3 KW,V=145 mm/m in,D=16mm×2mm。     

Functional neuroanatomy of the primate isocortical motor system

The concept of the primate motor cortex based on the cytoarchitectonic subdivision into areas 4 and 6 according to Brodmann or the functional subdivision into primary motor, supplementary motor, and lateral premotor cortex has changed in recent years. Instead, this cortical region is now regarded as a complex mosaic of different areas. This review article gives an overview of the structure and function of the isocortical part of the motor cortex in the macaque and human brain. In the macaque monkey, the primary motor cortex (Brodmann’s area 4 or area F1) with its giant pyramidal or Betz cells lies immediately anterior to the central sulcus. The non-primary motor cortex (Brodmann’s area 6) lies further rostrally and can be subdivided into three groups of areas: the supplementary motor areas ”SMA proper” (area F3) and ”pre-SMA” (area F6) on the mesial cortical surface, the dorsolateral premotor cortex (areas F2 and F7) on the dorsolateral convexity, and the ventrolateral premotor cortex (areas F4 and F5) on the ventrolateral convexity. The primary motor cortex is mainly involved in controlling kinematic and dynamic parameters of voluntary movements, whereas non-primary motor areas are more related to preparing voluntary movements in response to a variety of internal or external cues. Since a structural map of the human isocortical motor system as detailed as in the macaque is not yet available, homologies between the two species have not been firmly established. There is increasing evidence, however, that a similar organizational principle (i.e., primary motor cortex, supplementary motor areas, dorso- and ventrolateral premotor cortex) also exists in humans. Imaging studies have revealed that functional gradients can be discerned within the human non-primary motor cortex. More rostral cortical regions are active when a motor task is nonroutine, whereas more routine motor actions engage more caudal areas. Accepted: 3 July 2000     

自发性高血压大鼠主动脉弓重建的形态学研究

目的　研究高血压动脉重建规律,为揭示高血压主动脉弓的血流动力学特点提供形态学基础。　方法　应用组织学和计算机图像分析技术,对３６ 例ＳＨＲ和ＷＫＹ大鼠（各分４周、１６ 周和２６ 周）主动脉弓进行定量形态学研究。　结果　随着年龄增长,大鼠主动脉弓形态和显微结构发生重建。高血压主动脉弓重建以壁厚、中膜厚、管壁面积、中膜面积和中膜厚内径比以及血管平滑肌、弹性纤维和胶原纤维等结构成分的相对含量显著增大为特征。　结论　ＳＨＲ成年以前主动脉重建是年龄不断增长和血压逐步升高综合作用的结果,其中高血压是主要因素。大鼠主动脉弓形态结构在血管周向呈显著非均匀性,并在高血压重建中变得更为显著。     

停训练对大鼠骨骼肌超微结构和酶的影响

[目的]研究旨在观察停训对大鼠骨骼肌的超微结构以及氧化酶与无氧酶含量的影响.[方法]采用两月龄雄性大鼠44只,随机分为正常对照组(NC,16只)与力量耐力训练组(ST,28只),通过6周跳跃性力量耐力训练后,对ST组中的12只大鼠停训6周,分别对骨骼肌中酶的含量和超微结构进行采集. [结果]通过6周的停训之后,Gn、LDH、SDH以及ATPase含量均明显降低,线粒体体积减小,数量减少. [结论]停训可明显降低机体的有氧和无氧代谢能力.     

Structure and mechanical properties of Saxidomus purpuratus biological shells

The strength and fracture behavior of Saxidomus purpuratus shells were investigated and correlated with the structure. The shells show a crossed lamellar structure in the inner and middle layers and a fibrous/blocky and porous structure composed of nanoscaled particulates (∼100 nm diameter) in the outer layer. It was found that the flexure strength and fracture mode are a function of lamellar organization and orientation. The crossed lamellar structure of this shell is composed of domains of parallel lamellae with approximate thickness of 200–600 nm. These domains have approximate lateral dimensions of 10–70 μm with a minimum of two orientations of lamellae in the inner and middle layers. Neighboring domains are oriented at specific angles and thus the structure forms a crossed lamellar pattern. The microhardness across the thickness was lower in the outer layer because of the porosity and the absence of lamellae. The tensile (from flexure tests) and compressive strengths were analyzed by means of Weibull statistics. The mean tensile (flexure) strength at probability of 50%, 80–105 MPa, is on the same order as the compressive strength (∼50–150 MPa) and the Weibull moduli vary from 3.0 to 7.6. These values are significantly lower than abalone nacre, in spite of having the same aragonite structure. The lower strength can be attributed to a smaller fraction of the organic interlayer. The fracture path in the specimens is dominated by the orientation of the domains and proceeds preferentially along lamella boundaries. It also correlates with the color changes in the cross section of the shell. The cracks tend to undergo a considerable change in orientation when the color changes abruptly. The distributions of strengths, cracking paths, and fracture surfaces indicate that the mechanical properties of the shell are anisotropic with a hierarchical nature.     

基于乳化剂配比变化的乳膏微观结构与稳定性关联性研究

目的：利用因子分析探讨含司盘-吐温复配乳化剂乳膏的微观结构与物理稳定性之间的关联性。方法：通过显微观察、流变测量等技术表征乳膏微观结构;利用热重技术及近红外稳定性分析技术定量表征乳膏物理稳定性。结果：在司盘60-吐温80和司盘60-吐温60复配乳化剂乳膏中,随着司盘60比例的增加,乳膏电导值及其在50℃-70℃内失去的水有逐渐增加的趋势,偏光下呈现的球形层状液晶结构逐渐清晰且增多,70℃-110℃失去的水有逐渐降低的趋势。而黏弹性呈现先增后减的趋势,且司盘与吐温的比例分别在2∶2、1∶3时黏弹性最强。结论：稳定性与微观结构公因子关联性分析表明：乳膏在各种实验条件下的稳定性与乳膏“结构密集度”、“结构抗破坏能力”呈正相关,与“亲水凝胶相水分分布指数”呈负相关。