Population based quantification of dendrites: evidence for the lack of microtubule-associate protein 2a,b in Purkinje cell spiny dendrites

The high molecular weight isoforms (a and b) of microtubule-associate protein 2 (MAP2a,b) are widely believed to be specific markers for neuronal somata and dendrites. We analyzed and quantified MAP2a,b stained dendrites of the cerebellar molecular layer using a novel approach that segmented and 3D reconstructed them, and the results have been compared with those obtained by other methods, including single-cell reconstruction and analysis of electron micrographs. Our results show that the molecular layer dendritic volume fraction is lower than in the neocortex (10% compared to neocortical 29%). The low total volume fraction of dendrites in the molecular layer is best explained by the majority of the afferents to the dendrites being from the very densely packed parallel fibers, which allows the dendritic fields of individual neurons to be smaller and more compact than in the cerebral cortex. However, the MAP2a,b dendritic volume fraction is even lower (5.2%) than the total volume fraction of dendrites in the molecular layer (10%). Analysis of the material shows that this difference between the two results is due to the unexpected finding that there were few MAP2a,b stained Purkinje cell spiny dendrites.     

弱视患者发病机制及眼部结构的研究进展

弱视是一种儿童视觉发育关键期常见的眼科疾病,其发病机制复杂。传统观念认为弱视不会出现明显眼球器质性改变,但近年随着研究的深入,研究者们发现弱视患者不仅脑部解剖存在差异,在眼部结构也与正常人不尽相同,这为探索弱视发病机制提供了新的思路。本文就弱视患者的发病机制及眼部结构改变进行了总结,从发病机制、脉络膜厚度(CT)、眼部血管面积及密度、视网膜神经纤维层(RNFL)厚度以及弱视患者遮盖治疗后的眼部结构改变等方面进行综述。     

Functional morphology of the sound-generating labia in the syrinx of two songbird species

In songbirds, two sound sources inside the syrinx are used to produce the primary sound. Laterally positioned labia are passively set into vibration, thus interrupting a passing air stream. Together with subsyringeal pressure, the size and tension of the labia determine the spectral characteristics of the primary sound. Very little is known about how the histological composition and morphology of the labia affect their function as sound generators. Here we related the size and microstructure of the labia to their acoustic function in two songbird species with different acoustic characteristics, the white-crowned sparrow and zebra finch. Histological serial sections of the syrinx and different staining techniques were used to identify collagen, elastin and hyaluronan as extracellular matrix components. The distribution and orientation of elastic fibers indicated that the labia in white-crowned sparrows are multi-layered structures, whereas they are more uniformly structured in the zebra finch. Collagen and hyaluronan were evenly distributed in both species. A multi-layered composition could give rise to complex viscoelastic properties of each sound source. We also measured labia size. Variability was found along the dorso-ventral axis in both species. Lateral asymmetry was identified in some individuals but not consistently at the species level. Different size between the left and right sound sources could provide a morphological basis for the acoustic specialization of each sound generator, but only in some individuals. The inconsistency of its presence requires the investigation of alternative explanations, e.g. differences in viscoelastic properties of the labia of the left and right syrinx. Furthermore, we identified attachments of syringeal muscles to the labia as well as to bronchial half rings and suggest a mechanism for their biomechanical function.     

Optic neuritis: A mechanistic view

Acute demyelinating optic neuritis is a condition of the optic nerves characterized by inflammation, demyelination, and neurodegeneration. Optic neuritis is a relatively common demyelinating event, strongly associated with multiple sclerosis. A number of clinical, radiographic, retinal imaging, and electrophysiologic techniques have provided significant insight into the pathologic and pathophysiologic mechanisms of optic neuritis and its related disorder multiple sclerosis. The development of validated biomarkers within the anterior visual system has paved the way for novel investigations aimed at characterizing the processes of axonal loss and neurodegeneration, neuroprotection, and perhaps even neurorestoration strategies.     

New Applications of Photolabile Nitrobenzyl Groups in Polymers

This article describes progress in the author's laboratory in two new areas of photoresponsive polymers: (1) photochemical control of electrostatics, and (2) conjugated materials with photocleavable pendants. In both cases, incorporation of o‐nitrobenzyl esters (NBEs) imparts this photoreactivity. NBE‐derivatized, ring‐opening metathesis polymerization (ROMP)‐derived polycations form positive photoresist layer‐by‐layer (LbL) films that dissolve in base upon irradiation. NBE‐derivatized conjugated oligomers show photoactivated fluorescence, whereas NBE‐substituted polythiophenes are negative photoresists due to photolysis of solubilizing alkyl chains.     

Plexiform Fibrohistiocytic Tumor: Ultrastructural Studies May Aid in Discrimination from Cellular Neurothekeoma

ABSTRACT

Plexiform fibrohistiocytic tumor is a low-grade soft tissue malignancy that can at times be difficult to differentiate from the less biologically aggressive cellular neurothekeoma. The two entities, which may display identical clinical and histological features, cannot be distinguished by immunohistochemical or molecular diagnostic means. Electron microscopy may enable the accurate identification of problematic examples and thus aid in resolving these occasionally occurring diagnostic dilemmas. To illustrate typical variations in the ultrastructural appearance of plexiform fibrohistiocytic tumor, the authors present two diagnostically noncontroversial examples, and to demonstrate the potential diagnostic utility of electron microscopy in this setting, they present an example of plexiform fibrohistiocytic tumor that could not otherwise have been distinguished from cellular neurothekeoma.     

体外膈肌起搏器联合吞咽训练治疗重症消化道肿瘤化疗后呃逆患者吸入性肺炎的临床效果

目的 观察体外膈肌起搏器(EDP)联合吞咽训练治疗重症消化道肿瘤化疗后呃逆患者吸入性肺炎的临床效果.方法 按随机数字表法将65例重症消化道肿瘤化疗后出现呃逆继发吸入性肺炎的患者分为对照组(33例)和治疗组(32例).对照组给予基础治疗+吞咽训练,治疗组给予基础治疗+吞咽训练+EDP.观察患者的痰液细菌学培养检出结果,比...