Neurofilaments and microtubules in sensory neurons after peripheral nerve section

Summary Sensory neurons were examined in spinal ganglia of the rat 1 to 55 days after section of the plexus brachialis nerves. Only light neurons of the type A were investigated. Maximal reaction to axotomy was found 7 to 14 days after the operation. The majority of the axotomized perikarya developed central chromatolysis. In such neurons, Nissl bodies virtually disappeared from the central area of the neuron and formed a more or less continuous zone at the cell circumference. The cytocentrum became filled with large numbers of mitochondria, dense bodies and other organelles. Neurofilaments and microtubules were disarranged and ran at random among the accumulated particles. Microtubules were often more prominent in chromatolytic areas than neurofilaments. Both these organelles were rare in the peripheral areas filled with massed Nissl substance.Part of the neurons that did not show typical chromatolysis contained increased numbers of neurofilaments among Nissl bodies dispersed throughout the cytoplasm. Neurofilaments were roughly arrayed in bundles up to several microns wide; they were linked by cross-bridges and separated by distances of about 500 Å. Microtubules were rarely found in the filamentous areas. However, they were numerous in the axon hillock and in the initial segment where they formed fascicles similar to those described in normal neurons of other types.During the period from 14 to 55 days after axotomy, many perikarya recovering from chromatolysis contained enlarged bundles of neurofilaments with occasional microtubules among the restored Nissl bodies.Mean diameters of sensory neurons, measured 7 to 55 days after axotomy, in no instance exceeded those of contralateral control neurons. It thus appears that sensory perikarya do not increase in size either during the chromatolytic process or during the period of recovery.This project was supported by a grant from the Muscular Dystrophy Association of America, Inc. The main part of this study was done while the author was a Research Fellow in Anatomy at the Harvard Medical School, Boston. The author wishes to thank prof. S. L. Palay for his valuable advice and help received during her stay at the Department of Anatomy at the Harvard Medical School, under NIH training grant NBO5591.     

Effects of dorsal root section and occlusion of dorsal spinal artery on the neurotransmitter candidates in rat spinal cord

In order to obtain further evidence of putative neurotransmitters in primary sensory neurons and interneurons in the dorsal spinal cord, we have studied the effects of unilateral section of dorsal roots and unilateral occlusion of the dorsal spinal artery on cholinergic enzyme activity and on selected amino acid levels in the spinal cord. One week after sectioning dorsal roots from caudal cervical (C₇) to cranial thoracic (T₂) levels, the specific activity of choline acetyltransferase (ChAT) was significantly decreased and acetylcholinesterase (AChE) showed a tendency to decrease in the dorsal quadrant on the operated side of the spinal cord. Dorsal root sectioning had little effect on the levels of free glutamic acid or other amino acids in the dorsal spinal cord. These results suggest that primary sensory neurons may include some cholinergic axons, and that levels of putative amino acid transmitters are not regulated by materials supplied by axonal transport from the dorsal root ganglia. By contrast, one week following unilateral occlusion of the dorsal spinal artery, the activities of ChAT and AChE were unchanged in the operated quadrant of the spinal cord, while decreases of Asp, Glu, and GABA, and an increase in Tau were detected. These findings are consistent with the proposals that such amino acids, but not ACh, may function as neurotransmitter candidates in interneurons of the dorsal spinal cord.Abbreviation used ACh acetylcholine - AChE acetylcholinesterase - Asp aspartic acid - ChAT choline acetyltransferase - GABA -aminobutyric acid - Glu glutamic acid - Gly glycine - SP substance P - Tau taurine     

A focus on fixation

Three fixation issues related to immunostaining are discussed here: 1) Generally, a tissue block is fixed, then embedded and sectioned (pre-fixation). The type of fixative applied, crosslinking or coagulating, has an impact on selecting an epitope retrieval method. Individual antigens have a fixation-retrieval characteristic. 2) A long fixation time, especially with crosslinking fixatives, may compromise the result of immunostaining. This negative effect varies among different antigens and can be partially restored by applying a more sensitive/efficient detection system such as tyramide amplification. 3) Sections cut from a fresh frozen tissue block usually are acetone fixed (post-fixation). This was accepted as the “gold standard” for a long time. Post-fixation, however, may have serious consequences for preservation of small peptides leaking from the cut open cells, whereas this is not the case with pre-fixed intact cells. Consequently, the concept of an acetone post-fixed cryostat tissue section as “gold standard” no longer exists and a more appropriate use of the terms immunohistochemistry and immunocytochemistry therefore seems justified. For many antibodies, it is not known whether a formalin fixed, paraffin embedded tissue specimen is appropriate. Suggestions are made for creating a positive control cell block for testing such antibodies.     

An Estimation Procedure for the Joint Distribution of Spatial Direction and Thickness of Flat Bodies Using Vertical Sections Part I: Theoretical Considerations

In soil micromorphology fissures are considered in vertical sections. To get information about the properties of the soil the joint distribution of spatial direction and width is of interest. The fissures are mathematically generalized to flat bodies which form a stationary weighted surface process with the weight “thickness”. Because of stationarity a joint distribution of spatial direction and thickness exists in a “typical point” of the surface process. A suitable parametric family of distributions is assumed. The corresponding parameters can be estimated from measurements on the vertical sections. But on the sections only the visible thickness and the visible angle of a fissure can be measured. Therefore the joint distribution of these variables is expressed by the joint spatial distribution of spatial direction and thickness. This derived distribution depends on the same parameters. The Chi-Square method is proposed for the parameter estimation. The estimation procedure is demonstrated using the Bingham-Mardia distribution for the direction and the lognormal distribution for the thickness and by defining a way to correlate the mean thickness and the direction.     

甲状腺组织冷冻切片的优化

目的优化冷冻切片的关键条件,以期提高甲状腺组织冷冻制片效率、切片质量与染色效果。方法收集术中新鲜送检的甲状腺标本,通过对比实验,比较冷冻切片制作环节中取材厚度、速冻方法与染色方法等因素对制片质量的影响。结果甲状腺组织冷冻切片取材厚度以0.2~0.3cm为佳;预先制作“冰垫”的托头并于上方加盖冷冻冰锤,有利于提高速冻效率、提高组织结构清晰度、减少组织块崩裂、减少冰晶、减少裂隙;机染有利于提高染色优良率并减少染色时间。结论选择适当的取材厚度、优化速冻方法、采用优质的染色方法,可显著提高甲状腺组织冷冻切片的制片质量,为精准的术中病理诊断奠定基础。     

两种剖宫产术在疤痕子宫再次妊娠中的对比研究

目的：探究应用子宫下段剖宫产术（Lower uterine cesarean section,LUCS）和斯塔克剖宫产术（Stark cesarean section,SCS）于 疤痕子宫再次妊娠的效果。方法：选择2012 年3 月至2013 年10 月在我院再次妊娠的疤痕子宫产妇187 例,观察组95 例应用 LUCS,对照组92 例应用SCS。观察对比两组病患手术指标和术后并发症以及新生儿Apgar评分。结果：两组新生儿均成功存活。 观察组的手术出血量（293± 72）mL 和住院时间（4.1± 0.53）d,少于对照组(P 均为0.00),产后症状表现更好。观察组在产后出血、 产后发热以及产褥感染中的比例均低于对照组（P=0.02;P=0.01;P=0.04）。而且观察组未出现子宫破裂,盆腔粘连发生率为3.16 % （3/95）,少于对照组的13.04 %（12/92）（P=0.04,P=0.01）;观察组新生儿Apgar评分更高,差异均有统计学意义（P=0.00）。结论：应 用LUCS 于疤痕子宫再次妊娠的可行性更强,不仅减少产妇术后并发症的发生率,也提高了新生儿Apgar评分,值得临床推荐。     

腰麻硬膜外联合麻醉与硬膜外麻醉对剖宫产患者血流动力学的影响

目的:探讨腰麻硬膜外联合麻醉与硬膜外麻醉对剖宫产患者血流动力学的影响。方法:选择我院2013年12月至2014年12月收治的80例行剖宫产手术产妇,按随机数字表法平均分为A组及B组各40例,A组产妇使用腰麻硬膜外联合麻醉(CSEA),B组产妇使用硬膜外麻醉(EA),比较两组产妇麻醉效果,血流动力学变化、新生儿Apgar评分及产妇不良反应发生情况。结果:A组产妇麻醉效果Ⅲ级比率85.0%,明显高于B组的22.5%(P0.05)。A组产妇心率(HR)在胎儿娩出10 min(T3)及手术结束(T4)时刻明显高于B组,收缩压(SBP)和舒张压(DBP)在胎儿娩出即刻(T2)明显高于B组,平均动脉压(MAP)在麻醉前(T1)和麻醉后(T4)明显高于B组,每博输出量(SV)在T2时刻明显低于B组,比较差异具有统计学意义(P0.05);两组产妇心输出量(CO)各时刻比较差异无统计学意义(P0.05)。A组新生儿在娩出1 min时Apgar评分明显高于B组(P0.05)。A组不良反应发生率为5.0%,B组产妇不良反应发生率为10.0%,两组比较差异无统计学意义(P0.05)。结论:对剖宫产手术患者使用CSEA麻醉效果明显优于EA,且患者血流动力学更为稳定,麻醉效果较完善,安全性高,可应作为剖宫产手术首选的麻醉方式。     

The three-dimensional structure of the cyanobacterium Synechocystis sp. PCC 6803

To advance our knowledge of the model cyanobacterium Synechocystis sp. PCC 6803 we investigated the three-dimensional organization of the cytoplasm using standard transmission electron microscopy and electron tomography. Electron tomography allows a resolution of ~5 nm in all three dimensions, superior to the resolution of most traditional electron microscopy, which is often limited in part by the thickness of the section (70 nm). The thylakoid membrane pairs formed layered sheets that followed the periphery of the cell and converged at various sites near the cytoplasmic membrane. At some of these sites, the margins of thylakoid membranes associated closely along the external surface of rod-like structures termed thylakoid centers, which sometimes traversed nearly the entire periphery of the cell. The thylakoid membranes surrounded the central cytoplasm that contained inclusions such as ribosomes and carboxysomes. Lipid bodies were dispersed throughout the peripheral cytoplasm and often juxtaposed with cytoplasmic and thylakoid membranes suggesting involvement in thylakoid maintenance or biogenesis. Ribosomes were numerous and mainly located throughout the central cytoplasm with some associated with thylakoid and cytoplasmic membranes. Some ribosomes were attached along internal unit-membrane-like sheets located in the central cytoplasm and appeared to be continuous with existing thylakoid membranes. These results present a detailed analysis of the structure of Synechocystis sp. PCC 6803 using high-resolution bioimaging techniques and will allow future evaluation and comparison with gene-deletion mutants.Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.     

Implementation of X-ray Fluorescence Microscopy for Investigation of Elemental Abnormalities in Amyotrophic Lateral Sclerosis

The abnormalities of metallochemical reactions may contribute to the pathogenesis of Amyotrophic Lateral Sclerosis (ALS). In the present work, an investigation of the elemental composition of the gray matter, nerve cells and white matter from spinal cord tissues representing three ALS cases and five non-ALS controls was performed. This was done with the use of the synchrotron microbeam X-ray fluorescence technique (micro-SRXRF). The following elements were detected in the tissue sections: P, S, Cl, K, Ca, Fe, Cu, Zn and Br. A higher accumulation of Cl, K, Ca, Zn and Br was observed in the nerve cell bodies than in the surrounding tissue. Contrary to all other elements, Zn accumulation was lower in the white matter areas than in the gray matter ones. The results of quantitative analysis showed that there were no general abnormalities in the elemental accumulation between the ALS and the control group. However, for individual ALS cases such abnormalities were observed for the nerve cells. We also demonstrated differences in the elemental accumulation between the analyzed ALS cases.     

Introduction and verification of a novel method for measuring wood fiber length using a single cross section in Acacia mangium

A novel method for calculating the wood fiber length using a single cross section was devised and verified in Acacia mangium. This method is based on the ratio of cell tips to total cell number in a cross section related to the wood fiber. The fiber length was calculated using the single cross-section method and was compared with the measurements obtained using the conventional maceration method and the serial cross-section method. There was no significant difference among the three methods.