14 research outputs found
Correlative light and electron microscopy : strategies and applications
Correlative light and electron microscopy (CLEM) refers to the observation of the same structures or ultrastructures with both light microscopy (LM) and electron microscopy (EM). LM provides an overview of the studied material, and enables the quick localization of structures that are fluorescently labeled, while EM allows high resolution imaging of structures. The thesis describes several technical developments that allow CLEM. In the first chapters, methods are described for room temperature CLEM. This includes tissue labeling with fluorescent dyes in ultrathin resin sections, and fluorescence imaging before further preparation for EM and electron tomography. The methods are applied to tissue biopsies, and to the study of regulated exocytosis of Weibel-Palade bodies. In the following chapters, CLEM developments are extended with CLEM of vitreous samples, i.e. cryo-CLEM. Vitrification allows easy maintenance of fluorescent probes, and it allows correlation with cryo-EM, a technique that preserves biological structures to atomic resolution. The thesis describes the design of a microscope stage for cryo-fluorescence microscopy. Following cryo-FM, samples are studied directly by cryo-EM and cryo-electron tomography. The technique is used to study mitochondrial ultrastructure, and the role of actin in the exocytosis of pancreatic zymogen granules.FEI Company, SEN (Stichting ter bevordering van de elektronenmicroscopie in Nederland).UBL - phd migration 201
Comparison of outcome and characteristics between 6343 COVID-19 patients and 2256 other community-acquired viral pneumonia patients admitted to Dutch ICUs
Purpose: Describe the differences in characteristics and outcomes between COVID-19 and other viral pneumonia patients admitted to Dutch ICUs. Materials and methods: Data from the National-Intensive-Care-Evaluation-registry of COVID-19 patients admitted between February 15th and January 1th 2021 and other viral pneumonia patients admitted between January 1st 2017 and January 1st 2020 were used. Patients' characteristics, the unadjusted, and adjusted in-hospital mortality were compared. Results: 6343 COVID-19 and 2256 other viral pneumonia patients from 79 ICUs were included. The COVID-19 patients included more male (71.3 vs 49.8%), had a higher Body-Mass-Index (28.1 vs 25.5), less comorbidities (42.2 vs 72.7%), and a prolonged hospital length of stay (19 vs 9 days). The COVID-19 patients had a significantly higher crude in-hospital mortality rate (Odds ratio (OR) = 1.80), after adjustment for patient characteristics and ICU occupancy rate the OR was respectively 3.62 and 3.58. Conclusion: Higher mortality among COVID-19 patients could not be explained by patient characteristics and higher ICU occupancy rates, indicating that COVID-19 is more severe compared to other viral pneumonia. Our findings confirm earlier warnings of a high need of ICU capacity and high mortality rates among relatively healthy COVID-19 patients as this may lead to a higher mental workload for the staff. (c) 2021 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/)
"De kofschipper en het kathederboefje. De Vries & Te Winkel, de spelling en het WNT"
Multigranular exocytosis of Weibel-Palade bodies in vascular endothelial cells
Regulated exocytosis of Weibel-Palade bodies (WPBs) is a pivotal mechanism via which vascular endothelial cells initiate repair in response to injury and inflammation. Several pathways have been proposed to enable differential release of bioactive molecules from WPBs under different pathophysiologic conditions. Due to the complexity, many aspects of WPB biogenesis and exocytosis are still poorly understood. Herein, we have investigated the regulated exocytosis of the major WPB constituent, von Willebrand Factor (VWF), which upon its release forms strings of up to several millimeters long that capture circulating platelets and thereby initiate the formation of a haemostatic plug. Using correlative, fluorescence, and electron microscopic imaging techniques, we provide evidence that multigranular exocytosis is an important pathway for VWF release in secretagogue-challenged human umbilical vein endothelial cells. A novel membrane-delimited structure (secretory pod) was identified as the site of WPB coalescence and VWF exocytosis. Clathrin-coated profiles present on the secretory pods suggested remodeling via compensatory membrane retrieval. Small, 30- to 40-nm cytoplasmic vesicles (nanovesicles) mediated the fusion of WPBs with secretory pods. Multigranular exocytosis may facilitate VWF string formation by pooling the content of multiple WPBs. In addition, it may provide a novel mechanism for the differential release of WPB cargo.Microscopic imaging and technolog