Feedback-Driven Assembly of the Axon Initial Segment.

The axon initial segment (AIS) is a unique neuronal compartment that plays a crucial role in the generation of action potential and neuronal polarity. The assembly of the AIS requires membrane, scaffolding, and cytoskeletal proteins, including Ankyrin-G and TRIM46. How these components cooperate in AIS formation is currently poorly understood.

Comparative Ultrastructural and Stereological Analyses of Unruptured and Ruptured Saccular Intracranial Aneurysms.

Insight into processes leading to rupture of intracranial aneurysms (IAs) may identify biomarkers for rupture or lead to management strategies reducing the risk of rupture. We characterized and quantified (ultra)structural differences between unruptured and ruptured aneurysmal walls. Six unruptured and 6 ruptured IA fundi were resected after microsurgical clipping and analyzed by correlative light microscopy for quantitative analysis (proportion of the vessel wall area) and transmission electron microscopy for qualitative ultrastructural analysis.

Risk Factors for Intracranial Aneurysm Rupture: A Systematic Review.

Background: Intracranial aneurysm rupture prediction is poor, with only a few risk factors for rupture identified and used in clinical practice.

Objective: To provide an overview of all the risk factors (including genetic, molecular, morphological, and hemodynamic factors) that have potential for use in clinical practice.

Methods: We systematically searched PubMed and EMBASE and focused on factors that can be easily assessed in clinical practice, might be used for rupture prediction in clinical practice, and/or are potential targets for further research.

A novel infant milk formula concept: Mimicking the human milk fat globule structure.

Human milk (HM) provides all nutrients to support an optimal growth and development of the neonate. The composition and structure of HM lipids, the most important energy provider, have an impact on the digestion, uptake and metabolism of lipids. In HM, the lipids are present in the form of dispersed fat globules: large fat droplets enveloped by a phospholipid membrane.

Particle size dependent deposition and pulmonary inflammation after short-term inhalation of silver nanoparticles.

Background: Although silver nanoparticles are currently used in more than 400 consumer products, it is not clear to what extent they induce adverse effects after inhalation during production and use. In this study, we determined the lung burden, tissue distribution, and the induction and recovery of adverse effects after short-term inhalation exposure to 15 nm and 410 nm silver nanoparticles.

Methods: Rats were nose-only exposed to clean air, 15 nm silver nanoparticles (179 μg/m³) or 410 nm silver particles (167 μg/m³) 6 hours per day, for four consecutive days.

Gold nanocrystal labeling allows low-density lipoprotein imaging from the subcellular to macroscopic level.

Low-density lipoprotein (LDL) plays a critical role in cholesterol transport and is closely linked to the progression of several diseases. This motivates the development of methods to study LDL behavior from the microscopic to whole-body level. We have developed an approach to efficiently load LDL with a range of diagnostically active nanocrystals or hydrophobic agents.

Defect engineering in sedimentary colloidal photonic crystals.

In this paper, lithographic methods are successfully employed to create growth templates for colloidal self-assembly, enabling the inclusion of crystallographic defects at predetermined positions. It is shown that through smart template design stacking faults can be grown predictably into face centered cubic structures. More interestingly, by precise guiding of the stacking faults hollow intergrowth channels can be grown at predetermined lateral and vertical positions.

The influence of reactive oxygen species on cell cycle progression in mammalian cells.

Cell cycle regulation is performed by cyclins and cyclin dependent kinases (CDKs). Recently, it has become clear that reactive oxygen species (ROS) influence the presence and activity of these enzymes and thereby control cell cycle progression. In this review, we first describe the discovery of enzymes specialized in ROS production: the NADPH oxidase (NOX) complexes.

Endothelial cell senescence is associated with disrupted cell-cell junctions and increased monolayer permeability.

Background: Cellular senescence is associated with cellular dysfunction and has been shown to occur in vivo in age-related cardiovascular diseases such as atherosclerosis. Atherogenesis is accompanied by intimal accumulation of LDL and increased extravasation of monocytes towards accumulated and oxidized LDL, suggesting an affected barrier function of vascular endothelial cells. Our objective was to study the effect of cellular senescence on the barrier function of non-senescent endothelial cells.

A novel approach for intracellular 3D immuno-labeling for electron tomography.

Electron tomography (ET) is an indispensable high-resolution tool for three dimensional (3D) imaging in cell biology. When applied to immuno-labeled cells, ET can provide essential insights in both the cellular architecture and the dynamics. Current protocols for 3D immuno-labeling of intracellular antigens include permeabilization steps that cause random, extensive cell membrane disruption.

Cellular solid-state nuclear magnetic resonance spectroscopy.

Decrypting the structure, function, and molecular interactions of complex molecular machines in their cellular context and at atomic resolution is of prime importance for understanding fundamental physiological processes. Nuclear magnetic resonance is a well-established imaging method that can visualize cellular entities at the micrometer scale and can be used to obtain 3D atomic structures under in vitro conditions. Here, we introduce a solid-state NMR approach that provides atomic level insights into cell-associated molecular components.

Cobblestone HUVECs: a human model system for studying primary ciliogenesis.

Primary cilia are microtubule based sensory organelles that play an important role in maintaining cellular homeostasis. Malfunctioning results in a number of abnormalities, diseases (ciliopathies) and certain types of cancer. Morphological and biochemical knowledge on cilia/flagella, (early) ciliogenesis and intraflagellar transport is often obtained from model systems (e.

Impact of agglomeration state of nano- and submicron sized gold particles on pulmonary inflammation.

Background: Nanoparticle (NP) toxicity testing comes with many challenges. Characterization of the test substance is of crucial importance and in the case of NPs, agglomeration/aggregation state in physiological media needs to be considered. In this study, we have addressed the effect of agglomerated versus single particle suspensions of nano- and submicron sized gold on the inflammatory response in the lung.

Quantum dot and Cy5.5 labeled nanoparticles to investigate lipoprotein biointeractions via Förster resonance energy transfer.

The study of lipoproteins, natural nanoparticles comprised of lipids and apolipoproteins that transport fats throughout the body, is of key importance to better understand, treat, and prevent cardiovascular disease. In the current study, we have developed a lipoprotein-based nanoparticle that consists of a quantum dot (QD) core and Cy5.5 labeled lipidic coating.

Zebrafish Tie-2 shares a redundant role with Tie-1 in heart development and regulates vessel integrity.

Tie-2 is a member of the receptor tyrosine kinase family and is required for vascular remodeling and maintenance of mammalian vessel integrity. A number of mutations in the human TIE2 gene have been identified in patients suffering from cutaneomucosal venous malformations and ventricular septal defects. How exactly Tie-2 signaling pathways play different roles in both vascular development and vascular stability is unknown.

Golgi-associated cPLA2alpha regulates endothelial cell-cell junction integrity by controlling the trafficking of transmembrane junction proteins.

In endothelial cells specifically, cPLA2alpha translocates from the cytoplasm to the Golgi complex in response to cell confluence. Considering the link between confluence and cell-cell junction formation, and the emerging role of cPLA2alpha in intracellular trafficking, we tested whether Golgi-associated cPLA2alpha is involved in the trafficking of junction proteins. Here, we show that the redistribution of cPLA2alpha from the cytoplasm to the Golgi correlates with adherens junction maturation and occurs before tight junction formation.

Endothelial glycocalyx dimensions are reduced in growing collateral arteries and modulate leucocyte adhesion in arteriogenesis.

Unlabelled: During collateral artery growth, monocytes adhere to the endothelium and secrete cytokines from the perivascular space promoting arteriogenesis. Recently, the endothelial glycocalyx has been shown to modulate leucocyte infiltration in atherogenic regions. The role of this endothelial surface coating in arteriogenesis, however, has not been investigated so far.

Induced membrane domains as visualized by electron tomography and template matching.

Membranes play a crucial role in many cellular processes, and it is therefore not surprising that many electron tomographic studies in life sciences concern membranous structures. While these tomographic studies provide many new insights into membrane connections and continuities in three dimensions, they are mostly limited to a macro-morphological level. In this paper, we demonstrate that by combining electron tomography and three-dimensional template matching we are able to investigate membrane morphology at a new level: membrane domains in three dimensions.

Endothelial CD81 is a marker of early human atherosclerotic plaques and facilitates monocyte adhesion.

Aims: In a recent report, we established at the genome-wide level those genes that are specifically upregulated in the endothelium of atherosclerotic plaques in human arteries. As the transcriptome data revealed that mRNA for the tetraspanin family member CD81 is significantly and specifically upregulated in the endothelium overlying early atheroma, we set out to validate these results on the protein level, and investigate the functional consequences of CD81 upregulation.

Methods And Results: Immunohistochemical analysis in an independent set of donor arteries verified in the endothelium of early human atherosclerotic lesions the enhanced expression of CD81, which appears oxidative stress-dependent.

Anti-oxidant sensitivity of donor age-related gene expression in cultured fibroblasts.

Cultured human fibroblasts display age-dependent transcriptomic differences. We hypothesized that aging-associated oxidative stress affects gene expression, and monitored the transcriptome in confluent fibroblasts from young and old individuals cultured without and with a lipophilic and hydrophilic anti-oxidant mixture (vitamin E, quercetin, hydroxytyrosol and kaempferol). In cells derived from old subjects genes with lower expression were related to oxidative stress, growth and differentiation, cell cycle or metabolic enzymes and with higher expression to protein processing and docking, extracellular matrix, immune response, EGF-signalling and transcription.

Tetrahydrobiopterin, but not L-arginine, decreases NO synthase uncoupling in cells expressing high levels of endothelial NO synthase.

Endothelial NO synthase (eNOS) produces superoxide when depleted of (6R)-5,6,7,8-tetrahydro-L-biopterin (BH4) and L-arginine by uncoupling the electron flow from NO production. High expression of eNOS has been reported to have beneficial effects in atherosclerotic arteries after relatively short periods of time. However, sustained high expression of eNOS may have disadvantageous vascular effects because of uncoupling.

Mathematical modeling of vascular endothelial layer maintenance: the role of endothelial cell division, progenitor cell homing, and telomere shortening.

Maintenance of the endothelial cell (EC) layer of the vessel wall is essential for proper functioning of the vessel and prevention of vascular disorders. Replacement of damaged ECs could occur through division of surrounding ECs. Furthermore, EC progenitor cells (EPCs), derived from the bone marrow and circulating in the bloodstream, can differentiate into ECs.

Molecular events associated with reactive oxygen species and cell cycle progression in mammalian cells.

Cell cycle progression is regulated by a wide variety of external factors, amongst them are growth factors and extracellular matrix factors. During the last decades evidence has been obtained that reactive oxygen species (ROS) may also play an important role in cell cycle progression. ROS may be generated by external and internal factors.

Nitric oxide donor induces temporal and dose-dependent reduction of gene expression in human endothelial cells.

The present study tested the hypothesis that acute increases in nitric oxide (NO) exert substantial influences on gene transcription in endothelial cells (ECs) via guanylyl cyclase (GC). Human umbilical veins ECs (HUVECs) were exposed to 0.1, 1, and 10 mM of sodium nitroprusside (SNP) for 4 h and to 1 mM SNP or 250 microM of (Z)-1[N-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate (DETA-NONOate) for 2, 4, 8, and 24 h.

Oxidation of ER resident proteins upon oxidative stress: effects of altering cellular redox/antioxidant status and implications for protein maturation.

Previous work showed that from all cellular proteins, the endoplasmic reticulum (ER) resident proteins are most sensitive to oxidative stress [hydrogen peroxide (H(2)O(2))], as determined using the oxidation-sensitive, membrane-permeable, acetylTyrFluo probe. Because of the importance of these proteins in proper cellular functioning, we studied (a) whether modifying the cellular redox state/antioxidant status alters the susceptibility of those proteins toward H(2)O(2) oxidative stress and (b) whether H(2)O(2) affects ER function with regard to protein folding. The cellular redox and/or antioxidative capacity was modified in several ways.