ORCID Profile
0000-0001-7841-6952
Current Organisation
UiT Norges arktiske universitet
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Publisher: SPIE
Date: 18-10-2004
DOI: 10.1117/12.551016
Publisher: SPIE
Date: 16-09-2014
DOI: 10.1117/12.2062590
Publisher: SPIE
Date: 26-01-2006
DOI: 10.1117/12.667706
Publisher: Springer Science and Business Media LLC
Date: 29-11-2006
Publisher: Walter de Gruyter GmbH
Date: 23-02-2018
Abstract: Super-resolution fluorescence microscopy, also known as nanoscopy, has provided us with a glimpse of future impacts on cell biology. Far-field optical nanoscopy allows, for the first time, the study of sub-cellular nanoscale biological structures in living cells, which in the past was limited to electron microscopy (EM) (in fixed/dehydrated) cells or tissues. Nanoscopy has particular utility in the study of “fenestrations” – phospholipid transmembrane nanopores of 50–150 nm in diameter through liver sinusoidal endothelial cells (LSECs) that facilitate the passage of plasma, but (usually) not blood cells, to and from the surrounding hepatocytes. Previously, these fenestrations were only discernible with EM, but now they can be visualized in fixed and living cells using structured illumination microscopy (SIM) and in fixed cells using single molecule localization microscopy (SMLM) techniques such as direct stochastic optical reconstruction microscopy. Importantly, both methods use wet s les, avoiding dehydration artifacts. The use of nanoscopy can be extended to the in vitro study of fenestration dynamics, to address questions such as the following: are they actually dynamic structures, and how do they respond to endogenous and exogenous agents? A logical further extension of these methodologies to liver research (including the liver endothelium) will be their application to liver tissue sections from animal models with different pathological manifestations and ultimately to patient biopsies. This review will cover the current state of the art of the use of nanoscopy in the study of liver endothelium and the liver in general. Potential future applications in cell biology and the clinical implications will be discussed.
Publisher: Springer Science and Business Media LLC
Date: 21-01-2020
DOI: 10.1038/S41598-020-57652-0
Abstract: The liver is constantly exposed to dietary antigens, viruses, and bacterial products with inflammatory potential. For decades cellular uptake of virus has been studied in connection with infection, while the few studies designed to look into clearance mechanisms focused mainly on the role of macrophages. In recent years, attention has been directed towards the liver sinusoidal endothelial cells (LSECs), which play a central role in liver innate immunity by their ability to scavenge pathogen- and damage-associated molecular patterns. Every day our bodies are exposed to billions of gut-derived pathogens which must be efficiently removed from the circulation to prevent inflammatory and/or immune reactions in other vascular beds. Here, we have used GFP-labelled Enterobacteria phage T4 (GFP-T4-phage) as a model virus to study the viral scavenging function and metabolism in LSECs. The uptake of GFP-T4-phages was followed in real-time using deconvolution microscopy, and LSEC identity confirmed by visualization of fenestrae using structured illumination microscopy. By combining these imaging modalities with quantitative uptake and inhibition studies of radiolabelled GFP-T4-phages, we demonstrate that the bacteriophages are effectively degraded in the lysosomal compartment. Due to their high ability to take up and degrade circulating bacteriophages the LSECs may act as a primary anti-viral defence mechanism.
Publisher: AIP Publishing
Date: 30-07-2007
DOI: 10.1063/1.2760183
Abstract: The authors propose a low-pass 2f spatial filter for improving optical vortex beams in terms of circular geometry generated by a microfabricated wedge in free space. Compared with a conventional wedge, they are able to realize high-quality vortex beams with Q value close to 1 in free-space propagation. Physical mechanism behind the technique is found that it removes the diffraction artifacts as well as higher spatial frequency components of the quasivortex beams based on a wedge and hence the filtered beam is reconstructed with minimized distortions.
Publisher: Optica Publishing Group
Date: 02-10-2007
DOI: 10.1364/OL.32.002927
Abstract: We demonstrate that it is possible to generate high-order optical vortices from a single phase wedge by applying an incident beam with an annular intensity distribution. Various topological charges of optical vortices are realized by a static phase wedge when the position and radius of the annular illumination are changed accordingly.
Publisher: SPIE
Date: 10-02-2202
DOI: 10.1117/12.873779
Publisher: Optica Publishing Group
Date: 20-02-2006
DOI: 10.1364/AO.45.001153
Abstract: We propose using a solitary kinoform-type spiral phase plate structure to generate an array of vortices located in a single beam. Kinoform-type spiral surfaces allow each wavelength component of the phase modulation value to be wrapped back to its 2 pi equivalent for optical vortices of high charge. This allows the surface-relief profiles of high-charge vortices to be microfabricated with the same physical height as spiral phase plates of unity-charged optical vortices. The m-charged optical vortex obtained interacts with the inherent coherent background, which changes the propagation dynamics of the optical vortex and splits the initial m charge into /m/ unity-charged optical vortices within the same beam. Compared to a hologram, a multistart spiral phase plate is more efficient in the use of available spatial frequencies and beam energy and also is computationally less demanding. Furthermore, using microfabrication techniques will allow for greater achievable tolerances in terms of smaller feature sizes.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C4AN01181C
Abstract: Red blood cells squeeze through micro-capillaries as part of blood circulation in the body.
Publisher: Springer Science and Business Media LLC
Date: 24-04-2017
Publisher: Springer Science and Business Media LLC
Date: 07-12-2020
DOI: 10.1038/S42003-020-01473-4
Abstract: Correlative light and electron microscopy (CLEM) unifies the versatility of light microscopy (LM) with the high resolution of electron microscopy (EM), allowing one to zoom into the complex organization of cells. Here, we introduce photonic chip assisted CLEM, enabling multi-modal total internal reflection fluorescence (TIRF) microscopy over large field of view and high precision localization of the target area of interest within EM. The photonic chips are used as a substrate to hold, to illuminate and to provide landmarking of the s le through specially designed grid-like numbering systems. Using this approach, we demonstrate its applicability for tracking the area of interest, imaging the three-dimensional (3D) structural organization of nano-sized morphological features on liver sinusoidal endothelial cells such as fenestrations (trans-cytoplasmic nanopores), and correlating specific endo-lysosomal compartments with its cargo protein upon endocytosis.
Publisher: SPIE
Date: 11-02-2010
DOI: 10.1117/12.840390
Publisher: IOP Publishing
Date: 20-11-2004
Publisher: SPIE
Date: 26-08-2015
DOI: 10.1117/12.2187277
Publisher: SPIE
Date: 07-02-2005
DOI: 10.1117/12.571969
Publisher: SPIE
Date: 26-08-2015
DOI: 10.1117/12.2190249
Publisher: The Optical Society
Date: 21-09-2010
DOI: 10.1364/OE.18.021053
Publisher: OSA
Date: 2005
Publisher: Wiley
Date: 16-03-2020
Publisher: Proceedings of the National Academy of Sciences
Date: 15-11-2021
Abstract: We propose the integration of chip-based optical nanoscopy with high spatially sensitive quantitative phase microscopy to obtain three-dimensional (3D) morphology of liver sinusoidal endothelial cells (LSEC). LSEC contain large numbers of transcellular nanopores —“fenestrations”—in the plasma membrane, typically clustered in groups of 10 to 50 within areas called sieve plates. Determining the diameter and the height of fenestrated regions is an important indicator of a cell’s functionality, and these dimensions can be influenced by agents such as drugs. Our proposed multimodal microscope offers a solution for 3D nanoscale characterization of fenestration diameter and measurement of the optical thickness of the sieve plates.
No related grants have been discovered for Balpreet Singh Ahluwalia.