Ultrastructural analysis of dendritic spine necks reveals a continuum of spine morphologies

AbstractDendritic spines are membranous protrusions, with a bulbous head connected to the dendrite by a thin neck, and receive essentially all excitatory inputs in most mammalian neurons. Spines have a wide variety of morphologies that likely have a significant effect on their biochemical and electrical properties. The question of whether spines belong to distinct morphological or functional subtypes or constitute a continuum is still open. To discern this, it is important to measure spine necks objectively. Recent advances in electron microscopy enable automatic reconstructions of 3D spines with nanometer precision. Analyzing ultrastructural reconstructions from mouse neocortical neurons with computer vision algorithms, we demonstrate that the vast majority of spines can be rigorously separated into head and neck components. Analysis of the head and neck morphologies reveals a continuous distribution of parameters. The spine neck diameter, but not the neck length, was correlated with the head volume. Spines with larger head volumes often had a spine apparatus and pairs of spines in a post-synaptic cell contacted by the same axon had similar head volumes. Our data are consistent with a lack of morphological categories of spines and indicate that the morphologies of the spine neck and head are independently regulated. These results have repercussions for our understanding of the function of dendritic spines in neuronal circuits.

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Clay-Based Brick Porosity Estimation Using Image Processing Techniques

Journal of Intelligent Systems ◽

10.1515/jisys-2018-0191 ◽

2019 ◽

Vol 29 (1) ◽

pp. 1226-1234

Author(s):

Safa Jida ◽

Hassan Ouallal ◽

Brahim Aksasse ◽

Mohammed Ouanan ◽

Mohamed El Amraoui ◽

...

Keyword(s):

Electron Microscopy ◽

Image Processing ◽

Scanning Electron Microscopy ◽

Computer Vision ◽

Image Processing Techniques ◽

Processing Techniques ◽

Porosity Estimation ◽

Microscopy Images ◽

Scanning Electron

Abstract This work intends to apprehend and emphasize the contribution of image-processing techniques and computer vision in the treatment of clay-based material known in Meknes region. One of the various characteristics used to describe clay in a qualitative manner is porosity, as it is considered one of the properties that with “kill or cure” effectiveness. For this purpose, we use scanning electron microscopy images, as they are considered the most powerful tool for characterising the quality of the microscopic pore structure of porous materials. We present various existing methods of segmentation, as we are interested only in pore regions. The results show good matching between physical estimation and Voronoi diagram-based porosity estimation.

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Fenestrated Aortic Aneurysm Repair in Patients Treated Inside Versus Outside of Instructions for Use

Journal of Endovascular Therapy ◽

10.1177/15266028211068762 ◽

2022 ◽

pp. 152660282110687

Author(s):

Jordan R. Stern ◽

Céline Deslarzes-Dubuis ◽

Kenneth Tran ◽

Jason T. Lee

Keyword(s):

Univariate Analysis ◽

Aortic Aneurysms ◽

Neck Length ◽

Cox Proportional Hazard ◽

Potential Association ◽

Contrast Volume ◽

Instructions For Use ◽

Aneurysm Repair ◽

Neck Diameter

Objectives: The aim of this study was to compare outcomes of patients treated with the Cook Zenith Fenestrated (ZFEN) device for juxtarenal aortic aneurysms inside versus outside the IFU. Methods: We retrospectively reviewed our institutional ZFEN database for cases performed between 2012 and 2018, with analysis performed in 2020 in order to report midterm outcomes. The cohort was stratified based on treatment inside (IFU group) and outside (non-IFU group) the IFU for criteria involving the proximal neck: neck length 4 to 14 mm, neck diameter 19 to 31 mm, and neck angulation ≤45°. Patients with thoracoabdominal aneurysms or concurrent chimney grafting were excluded. The primary outcomes in question were mortality, type 1a endoleak, and reintervention. Univariate and multivariate analyses were performed to determine associations between adherence to IFU criteria and outcomes. Results: We identified 100 consecutive patients (19% female, mean age 73.6 years) for inclusion in this analysis. Mean follow-up was 21.6 months. Fifty-four patients (54%) were treated outside the IFU because of inadequate neck length (n=48), enlarged neck diameter (n=10), and/or excessive angulation (n=16). Eighteen patients were outside IFU for two criteria, and one patient was outside IFU for all three. Non-IFU patients were exposed to higher radiation doses (3652 vs 5445 mGy, p=0.008) and contrast volume (76 vs 95 mL, p=0.004). No difference was noted between IFU and non-IFU groups for 30-day mortality (0% vs 3.7%, p=0.18), or type 1a endoleak (0% vs 1.9%, p=0.41). Reintervention was also similar between cohorts (13% vs 27.8%, p=0.13). Being outside IFU for neck diameter or length was each borderline significant for higher reintervention on univariate analysis (p=0.05), but this was not significant on multivariate Cox proportional hazard modeling (HR 1.82 [0.53–6.25]; 2.03 [0.68–7.89]), respectively. No individual IFU deviations were associated with the primary outcomes on multivariate analysis, nor being outside IFU for multiple criteria. Conclusions: Patients with juxtarenal aortic aneurysms may be treated with the ZFEN device with moderate deviations from the IFU. While no differences were seen in mortality or proximal endoleak, larger studies are needed to examine the potential association between IFU nonadherence and reinterventions and close follow-up is warranted for all patients undergoing such repair.

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Anatomical Predictors of Endoleaks or Migration After Endovascular Aneurysm Sealing

Journal of Endovascular Therapy ◽

10.1177/1526602818808296 ◽

2018 ◽

Vol 25 (6) ◽

pp. 719-725 ◽

Cited By ~ 7

Author(s):

Kim van Noort ◽

Johannes T. Boersen ◽

Aleksandra C. Zoethout ◽

Richte C. L. Schuurmann ◽

Jan M. M. Heyligers ◽

...

Keyword(s):

Regression Analysis ◽

Large Scale ◽

High Volume ◽

Control Group ◽

Neck Length ◽

Aortic Neck ◽

Distal Migration ◽

Aneurysm Growth ◽

Instructions For Use ◽

Neck Diameter

Purpose: To identify preoperative anatomical aortic characteristics that predict seal failures after endovascular aneurysm sealing (EVAS) and compare the incidence of events experienced by patients treated within vs outside the instructions for use (IFU). Methods: Of 355 patients treated with the Nellix EndoVascular Aneurysm Sealing System (generation 3SQ+) at 3 high-volume centers from March 2013 to December 2015, 94 patients were excluded, leaving 261 patients (mean age 76±8 years; 229 men) for regression analysis. Of these, 83 (31.8%) suffered one or more of the following events: distal migration ⩾5 mm of one or both stent frames, any endoleak, and/or aneurysm growth >5 mm. Anatomical characteristics were determined on preoperative computed tomography (CT) scans. Patients were divided into 3 groups: treated within the original IFU (n=166), outside the original IFU (n=95), and within the 2016 revised IFU (n=46). Categorical data are presented as the median (interquartile range Q1, Q3). Results: Neck diameter was significantly larger in the any-event cohort vs the control cohort [23.7 mm (21.7, 26.3) vs 23.0 mm (20.9, 25.2) mm, p=0.022]. Neck length was significantly shorter in the any-event cohort [15.0 mm (10.0, 22.5) vs 19.0 mm (10.0, 21.8), p=0.006]. Maximum abdominal aortic aneurysm (AAA) diameter and the ratio between the maximum AAA diameter and lumen diameter in the any-event group were significantly larger than the control group (p=0.041 and p=0.002, respectively). Regression analysis showed aortic neck diameter (p=0.006), neck length (p=0.001), and the diameter ratio (p=0.011) as significant predictors of any event. In the comparison of events to IFU status, 52 (31.3%) of 166 patients in the inside the original IFU group suffered an event compared to 13 (28.3%) of 46 patients inside the 2016 IFU group (p=0.690). Conclusion: Large neck diameter, short aortic neck length, and the ratio between the maximum AAA and lumen diameters are preoperative anatomical predictors of the occurrence of migration (⩾5 mm), any endoleak, and/or aneurysm growth (>5 mm) after EVAS. Even under the refined 2016 IFU, more than a quarter of patients suffered from an event. Improvements in the device seem to be necessary before this technique can be implemented on a large scale in endovascular AAA repair.

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Electron Microscopy Analysis of AMPA Receptors in Dendritic Spines

Ionotropic Glutamate Receptor Technologies - Neuromethods ◽

10.1007/978-1-4939-2812-5_5 ◽

2016 ◽

pp. 61-69

Author(s):

Audra A. Kramer ◽

Amber N. Petersen ◽

Nashaat Z. Gerges

Keyword(s):

Electron Microscopy ◽

Dendritic Spines ◽

Ampa Receptors ◽

Electron Microscopy Analysis ◽

Microscopy Analysis

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A Computer-Vision-Guided Robot Arm for Automatically Placing Grids in Pioloform Film Preparation

Methods and Protocols ◽

10.3390/mps2010009 ◽

2019 ◽

Vol 2 (1) ◽

pp. 9 ◽

Cited By ~ 1

Author(s):

Markus Peurla ◽

Pekka Hänninen ◽

Eeva-Liisa Eskelinen

Keyword(s):

Electron Microscopy ◽

Computer Vision ◽

Transmission Electron Microscopy ◽

Current Practice ◽

Low Cost ◽

Routine Laboratory ◽

Robot Arm ◽

Laboratory Procedure ◽

Transmission Electron ◽

Film Preparation

Preparing pioloform/formvar support films on transmission electron microscopy (TEM) grids is a routine laboratory procedure in practically all electron microscopy units. In current practice, these grids are manually placed on the support film one by one using special tweezers, a process requiring a steady hand. The work is often ergonomically awkward to continue for a longer period of time. In this article, we describe a low-cost, computer vision-guided robot arm that automatically places the grids on the film. The success rate of the prototype robot is 90%, which is comparable to an experienced laboratory technician.

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Molecular Architecture of Synaptic Actin Cytoskeleton in Hippocampal Neurons Reveals a Mechanism of Dendritic Spine Morphogenesis

Molecular Biology of the Cell ◽

10.1091/mbc.e09-07-0596 ◽

2010 ◽

Vol 21 (1) ◽

pp. 165-176 ◽

Cited By ~ 235

Author(s):

Farida Korobova ◽

Tatyana Svitkina

Keyword(s):

Electron Microscopy ◽

Actin Cytoskeleton ◽

Actin Filament ◽

Dendritic Spines ◽

Dendritic Spine ◽

Myosin Ii ◽

Capping Protein ◽

Dominant Feature ◽

Presynaptic Boutons ◽

Spine Morphogenesis

Excitatory synapses in the brain play key roles in learning and memory. The formation and functions of postsynaptic mushroom-shaped structures, dendritic spines, and possibly of presynaptic terminals, rely on actin cytoskeleton remodeling. However, the cytoskeletal architecture of synapses remains unknown hindering the understanding of synapse morphogenesis. Using platinum replica electron microscopy, we characterized the cytoskeletal organization and molecular composition of dendritic spines, their precursors, dendritic filopodia, and presynaptic boutons. A branched actin filament network containing Arp2/3 complex and capping protein was a dominant feature of spine heads and presynaptic boutons. Surprisingly, the spine necks and bases, as well as dendritic filopodia, also contained a network, rather than a bundle, of branched and linear actin filaments that was immunopositive for Arp2/3 complex, capping protein, and myosin II, but not fascin. Thus, a tight actin filament bundle is not necessary for structural support of elongated filopodia-like protrusions. Dynamically, dendritic filopodia emerged from densities in the dendritic shaft, which by electron microscopy contained branched actin network associated with dendritic microtubules. We propose that dendritic spine morphogenesis begins from an actin patch elongating into a dendritic filopodium, which tip subsequently expands via Arp2/3 complex-dependent nucleation and which length is modulated by myosin II-dependent contractility.

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