Structure and function of endothelial caveolae

Caveolae are spherical invaginations of the plasma membrane and associated vesicles that are found at high surface densities in most cells, endothelia included. Their structural framework has been shown to consist of oligomerized caveolin molecules interacting with cholesterol and sphingolipids. Caveolae have been involved in many cellular functions such as endocytosis, signal transduction, mechano-transduction, potocytosis, and cholesterol trafficking. Some confusion still persists in the field with respect to the relationship between caveolae and the lipid rafts, which have been involved in many of the above functions. In addition to all these, endothelial caveolae have been involved in capillary permeability by their participation in the process of transcytosis. This short review will focus on their structure and components, methods used to determine these components, and the role of caveolae in the transendothelial exchanges between blood plasma and the interstitial fluid.     

Structure and function of the yeast vacuole and its role in autophagy

The vacuole of the yeast Saccharomyces cerevisiae plays an important role in pH- and ion-homeostasis, and is used as a storage compartment for ions. Another important function of the vacuole, especially during nutrient limitation, is the bulk degradation of proteins and even whole organelles. To carry these proteins into the vacuolar lumen, sophisticated transport pathways have evolved. In this review, starvation-induced autophagy and its relationship to the specific cytoplasm to vacuole targeting (cvt-) pathway of proaminopeptidase I is discussed. A further topic is the specific vacuolar uptake and degradation of peroxisomes in Pichia pastoris cells via micro- and macroautophagy.     

Structure and function of the bat superior olivary complex

The superior olivary complex (SOC) is a mammalian auditory brainstem structure that contains several nuclei. Some of them are part of the ascending system projecting to higher auditory centers, others belong to the descending system projecting to the cochlear nuclei or the cochlea itself. The main nuclei of the ascending system, the lateral and medial superior olive (LSO, MSO), as well as the lateral and medial nuclei of the trapezoid body (LNTB, MNTB), have been traditionally associated with sound localization. Here we review the results of recent studies on the main SOC nuclei in echolocating bats. These studies suggest that some SOC structures and functions are highly conserved across mammals (e.g., the LSO, which is associated with interaural intensity difference processing), while others are phylogenetically highly variable in both form and function (e.g., the MSO, traditionally associated with interaural time difference processing). For the MSO, these variations indicate that we should broaden our view regarding what functions the MSO might participate in, since its function in echolocation seems to lie in the context of pattern recognition rather than sound localization. Furthermore, across bat species, variations in the form and physiology of the MSO can be linked to specific behavioral adaptations associated with different echolocation strategies. Finally, the comparative approach, including auditory specialists such as bats, helps us to reach a more comprehensive view of the functional anatomy of auditory structures that are still poorly understood, like the nucleus of the central acoustic tract (NCAT).     

Structure and function of the extracellular matrix of anuran eggs

The extracellular matrix (ECM) surrounding the anuran egg is composed of jelly coat layers, an envelope, and the perivitelline space, which separates the envelope from the egg plasma membrane. Both the jelly coat layers and egg envelopes are required for fertilization in anurans. This paper reviews the current understanding of the structure-function relations of the ECM, with emphasis on the egg envelope. The fibrous egg envelope exists in four related forms. The envelope forms differ in their ultrastructures, macromolecular compositions, and cellular functions. After the oocyte is released from the ovary, conversion of one envelope form to another is brought about by factors secreted by the oviduct prior to fertilization and by factors released from the egg in the sperm-triggered cortical reaction. An additional extracellular matrix structure, located in the perivitelline space, has recently been identified in Xenopus laevis, as well as a previously undescribed reorganization of envelope fibers occurring at fertilization. The molecular changes in the ECM glycoproteins (limited proteolysis, lectin-ligand binding, and conformational changes) and the oviductal and egg macromolecules responsible for the conversion of envelope forms are discussed. New experimental evidence that supports the lectin-ligand hypothesis for the formation of the fertilization layer is presented. It is proposed that the molecular changes in the ECM are responsible for the ultrastructural alterations of the ECM and for modifications of the fertilization and developmental functions of the anuran egg ECM.     

Structure and function of frozen cells: freezing patterns and post-thaw survival.

Freezing patterns and post-thaw survival of cells varies with different cooling rates. The optimal cooling rates, indicating the highest percentage survival, were different in yeast and red blood cells. A difference of freezing patterns was also noticed in preparations frozen above and below the optimal cooling rate for each cell, namely, cell shrinkage at lower rates and intracellular ice formation at higher rates which showed similar trends in both the cells, even though there was some shifting of the optimum. Ultra-rapid freezing and addition of cryoprotectants are useful ways to minimize ice crystal formation and to cause such ice formations to approach the vitreous state. Ice crystals are hardly detectable in yeast cells as well as in erythrocytes, when these cells are frozen ultra-rapidly in the presence of cryoprotective agents in moderate concentration.     

Degeneration and regeneration of ganglion cell axons

The retino-tectal system has been used to study developmental aspects of axon growth, synapse formation and the establishment of a precise topographic order as well as degeneration and regeneration of adult retinal ganglion cell (RGC) axons after axonal lesion. This paper reviews some novel findings that provide new insights into the mechanisms of developmental RGC axon growth, pathfinding, and target formation. It also focuses on the cellular and molecular cascades that underlie RGC degeneration following an axonal lesion and on some therapeutic strategies to enhance survival of axotomized RGCs in vivo. In addition, this review deals with problems related to the induction of regeneration after axonal lesion in the adult CNS using the retino-tectal system as model. Different therapeutic approaches to promote RGC regeneration and requirements for specific target formation of regenerating RGCs in vitro and in vivo are discussed.     

Glucocorticoid-induced pnmt-immunoreactive sympathetic cells in the superior cervical ganglion of the rat

Light and electron microscopic immunocytochemical techniques were used to study the effect of glucocorticoids on the development of phenylethanolamine-N-methyltransferase (PNMT)-immunoreactive cells in the superior cervical ganglion (SCG) of early postnatal rats. Rats were injected daily with hydrocortisone acetate on postnatal days 2—6. The first PNMT-immunoreactive cells were detected 6 hours after the first glucocorticoid injection and their number increased after subsequent injections. No PNMT-immunoreactive cells were detected in uninjected controls. PNMT-immunoreactive fibres were seen in the ganglion 6 hours after the first glucocorticoid injection. The PNMT-immunoreactive cells consistently showed processes 2 days after beginning the glucocorticoid treatment, and long processes and fibre networks were seen in ganglia of 7-day-old rats. However, no PNMT-immunoreactive fibres were seen in the iris, which is innervated by the SCG. Ultrastructurally, most of the PNMT-immunoreactive cells had the look of small granule-containing (SGC) cells, including heterochromatin clumps along the nuclear envelope and in the center of the nucleoplasm as well as dense core vesicles. SGC cells, nonimmunoreactive to PNMT antiserum, also were seen. However, some PNMT-immunoreactive cells showed ultrastructural characteristics of nerve cells. In contrast to the SGC cells, these cells were characterized by a voluminous cytoplasm, dispersed nuclear heterochromatin, and a lack of granular vesicles. These results demonstrate that glucocorticoids induce PNMT immunoreactivity both in SGC cells and also in cells with characteristics of principal neurons.     

Distribution of GABA and glycine receptors on bipolar and ganglion cells in the mammalian retina

The amino acids GABA and glycine mediate synaptic transmission via specific neurotransmitter receptors. Molecular cloning studies have shown that there is a great diversity of GABA and glycine receptors. In the present article, the distribution of GABA and glycine receptors on identified bipolar and ganglion cell types in the mammalian retina is reviewed. Immunofluorescence obtained with antibodies against GABA and glycine receptors is punctate. Electron microscopy shows that the puncta represent a cluster of receptors at synaptic sites. Bipolar cell types were identified with immunohistochemical markers. Double immunofluorescence with subunit-specific antibodies was used to analyze the distribution of receptor clusters on bipolar axon terminals. The OFF cone bipolar cells seem to be dominated by glycinergic input, whereas the ON cone bipolar and rod bipolar cells are dominated by GABAergic input. Ganglion cells were intracellularly injected with Neurobiotin, visualized with Streptavidin coupled to FITC, and subsequently stained with subunit specific antibodies. The distribution and density of receptor clusters containing the alpha1 subunit of the GABA(A) receptor and the alpha1 subunit of the glycine receptor, respectively, were analyzed on midget and parasol cells in the marmoset (a New World monkey). Both GABA(A) and glycine receptors are distributed uniformly along the dendrites of ON and OFF types of parasol and midget ganglion cells, indicating that functional differences between these subtypes of ganglion cells are not determined by GABA or glycinergic input.     

Freeze-fracture and immunomorphological analysis of spiral ganglion cells

Freeze-fracture analysis of adult spiral ganglion cells of CBA/CBA mice revealed two types of membrane specializations. Most cells (type I) had a smooth surface and were surrounded by Schwann cells. Type II spiral ganglion cells showed numerous membrane specializations with well-delineated indentations similar to those previously found on hair cells adjacent to afferent and efferent nerve endings. Immunomorphological analysis (using well-defined monoclonal antibodies directed against different subclasses of intermediate filament proteins) revealed a unique co-expression of neurofilaments, vimentin and cytokeratins in spiral ganglion cells of 8-to 22-week human fetuses.     

Development of spiral ganglion cells in mammalian cochlea

The development of the spiral ganglion in the cat, the rat, and the mouse was studied by electron microscopy, from fetal stages in the cat and from birth in the rodent. In the earliest stages, a single population of ganglion cells is present. Immature spiral ganglion neurons possess small perisomatic processes that seem to disappear with development, before the myelination ganglion cells are surrounded by one or two layers of Schwann cell processes. With maturation, the Schwann process increases in number around the perikaryon and its processes, which leads to the onset of myelination. The onset of myelination of the cell body processes is asynchronous. The perikaryon may be delayed in myelination by several days. Moreover, ganglion neurons from a given region of the cochlea do not myelinate simultaneously. The differentiation of two types of fibers in the intraganglionic spiral bundle and the first appearance of TII neurons occurs around birth in the cat and a few days after birth for the rat and the mouse. The distinction of TII cells is possible due to characteristic accumulation of neurofilamentous structures in the cytoplasm.     

高血压脑出血脑疝手术效果及影响因素分析

目的 :分析高血压脑出血脑疝手术效果及影响因素,探讨高血压脑出血脑疝的预后预测指标。方法 :回顾性分析2013年2月—2016年2月于我院接受手术治疗的高血压脑出血脑疝患者105例资料。按照患者术后6个月预后质量,将格拉斯哥预后评分(GOS)Ⅳ~Ⅴ级者纳入预后良好组,将Ⅰ~Ⅲ级者纳入预后不良组,分析年龄、GCS评分、血肿量、手术时机等因素对患者预后的影响。结果:105例患者中,预后良好46例(43.81%),预后不良59例(56.19%)。大量血肿、GCS评分≤8分、脑室积血、中线移位≥1 cm、术后再出血、术后肺部感染为影响高血压脑出血脑疝手术效果的独立危险因素,发病后6 h内手术为保护性因素(P<0.05)。结论 :急诊大骨瓣减压血肿清除术对合并脑疝患者效果尚可,充分减压,尽早实施手术、完善围术期综合治疗,有望降低患者病死、病残率。     

肾上腺节细胞神经瘤的多排螺旋CT诊断价值

目的:探讨肾上腺节细胞神经瘤的螺旋CT表现及鉴别诊断。方法:回顾分析9例经手术病理证实的肾上腺节细胞神经瘤的螺旋CT扫描资料,重点分析其强化特点。结果:9例肾上腺节细胞神经瘤6例位于右侧,3例位于左侧。病灶呈圆形或椭圆形,边界清晰。9例患者CT扫描可见肿物为实性7例,病灶密度均匀,2例病灶内伴有钙化。增强扫描后8例病灶呈进行性均匀强化。结论:肾上腺节细胞神经瘤CT影像表现具有一定的特征性,多排螺旋CT不仅能作出正确定位并且能比较准确进行定性诊断。CT平扫及增强扫描是本病手术之前的主要诊断依据。     

描述变胞机构构态变换的一种新方法及其在构型综合中的应用

通过分析变胞机构的拓扑构态变换过程,提出一种能描述杆件减少过程中任意杆件合并的矩阵表达新方法,此方法不需要进行行列变换就可得到简洁的终态矩阵,且不影响原机构杆件的编号。以此方法为基础,阐述杆件数增加或不变的变胞机构拓扑构态变换的数学描述和实现方法。根据变胞机构构态变化规律和平面机构构型综合的拓扑相关性,提出基于变胞机构拓扑构态变换的数学描述进行平面闭链机构构型综合的新方法,给出单自由度闭链构型综合的实现方法和步骤,并以8杆机构构型综合为例进行应用说明。     

柄海鞘神经节的透射电镜观察

本文利用透射电镜观察了柄海鞘(Styela clava)神经节的超微结构.结果显示,神经节的神经细胞内线粒体及核糖体含量丰富;含有大量散在分布的有颗粒囊泡和无颗粒囊泡;神经纤维为有髓神经纤维.     

汽车起动系异常烧毁与起动机设计间隙探讨

针对车辆起动系的偶发异常烧毁故障展开试验、分析与研究,探讨强制啮合式起动机和机械柔性啮合式起动机的工作过程与设计间隙的作用,给出了降低起动机非正常工作状态故障率的建议,为车辆电气系统匹配与起动机部件设计提供参考。     

浅谈乘用车空调箱成本构成及应用

结合企业实际的情况,运用成本分析及多元线性回归等理论知识,得出的在项目前期就能够快速高效使用的方法,来切实解决企业成本控制中存在的一些问题。以乘用车空调箱作为研究对象,通过多元线形回归,分析成本构成,并且阐述了其普遍应用价值。     

面向对象分析与设计技术(OOA&D)及统一建模语言(UML)在产品结构管理中的应用

产品结构是产品数据管理的核心内容。采用面向对象分析与设计技术以及统一建模语言开发产品结构管理软件，这一技术的应用减少了软件开发成本以及开发周期，提高了软件质量。     

产品结构树在PDM中的研究与实现

本文分析探讨了产品数据管理系统中产品结构树的生成方式,并提出了关系型数据库中物料的一种高效数据库存储结构。     

糖尿病消化不良患者的自主神经功能及其对近端胃功能影响

目的 :探讨糖尿病消化不良患者的自主神经功能及其与近端胃功能的相关性。方法:选取2010年3月²012年7月间于我院消化科就诊并出现胃肠道症状的糖尿病患者40例以及健康成人30例,通过标准心血管反射试验、水负荷试验测定自主神经功能及近端胃功能,对比分析糖尿病消化不良患者的自主神经功能及其对近端胃功能的影响。结果 :经过标准心血管反射试验发现,糖尿病消化不良患者的副交感神经、交感神经、自主神经的功能评分与对照组相比,分值显著升高(P均<0.05),以副交感神经功能受损情况更为严重(P<0.01);糖尿病消化不良患者中,自主神经正常仅3例,自主神经早期累及17例,明确累及20例,异常的比例达92.5%,与对照组相比,自主神经功能异常人数显著增加;糖尿病消化不良患者的阈值饮水量、饱足饮水量与对照组相比显著减少;糖尿病消化不良患者饱足饮水后,其近端胃面积和周长均变小,与对照组相比差异具有统计学意义(P<0.05),而远端胃面积和周长变化增大,但与对照组相比无统计学意义(P>0.05);糖尿病消化不良患者的交感神经功能评分与患者阈值饮水量和饱足饮水量时近端胃的横截面周长的变化呈负相关性(r=-0.574,P<0.01)。结论 :糖尿病消化不良患者的自主神经功能受到损伤,与患者的近端胃功能存在一定相关性,但二者之间的相互影响有待进一步研究。     

“权力—利益”结构中的教师

无论是基于教师自身体验的解析,还是立足社会公众经验的审视,＂教师是谁＂都是当下教师教育与教育改革绕不开的一个议题。学校不仅仅是＂教育＂机构,在学校日常运作中,不同权力主体都在构筑不同的利益,学校生活呈现为复杂的＂权力-利益＂结构。在这个结构网络中,教师的存在呈现为象征性、区隔性、原子化。